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1/*
2 * kernel/sched/core.c
3 *
4 * Kernel scheduler and related syscalls
5 *
6 * Copyright (C) 1991-2002 Linus Torvalds
7 *
8 * 1996-12-23 Modified by Dave Grothe to fix bugs in semaphores and
9 * make semaphores SMP safe
10 * 1998-11-19 Implemented schedule_timeout() and related stuff
11 * by Andrea Arcangeli
12 * 2002-01-04 New ultra-scalable O(1) scheduler by Ingo Molnar:
13 * hybrid priority-list and round-robin design with
14 * an array-switch method of distributing timeslices
15 * and per-CPU runqueues. Cleanups and useful suggestions
16 * by Davide Libenzi, preemptible kernel bits by Robert Love.
17 * 2003-09-03 Interactivity tuning by Con Kolivas.
18 * 2004-04-02 Scheduler domains code by Nick Piggin
19 * 2007-04-15 Work begun on replacing all interactivity tuning with a
20 * fair scheduling design by Con Kolivas.
21 * 2007-05-05 Load balancing (smp-nice) and other improvements
22 * by Peter Williams
23 * 2007-05-06 Interactivity improvements to CFS by Mike Galbraith
24 * 2007-07-01 Group scheduling enhancements by Srivatsa Vaddagiri
25 * 2007-11-29 RT balancing improvements by Steven Rostedt, Gregory Haskins,
26 * Thomas Gleixner, Mike Kravetz
27 */
28
29#include <linux/mm.h>
30#include <linux/module.h>
31#include <linux/nmi.h>
32#include <linux/init.h>
33#include <linux/uaccess.h>
34#include <linux/highmem.h>
35#include <asm/mmu_context.h>
36#include <linux/interrupt.h>
37#include <linux/capability.h>
38#include <linux/completion.h>
39#include <linux/kernel_stat.h>
40#include <linux/debug_locks.h>
41#include <linux/perf_event.h>
42#include <linux/security.h>
43#include <linux/notifier.h>
44#include <linux/profile.h>
45#include <linux/freezer.h>
46#include <linux/vmalloc.h>
47#include <linux/blkdev.h>
48#include <linux/delay.h>
49#include <linux/pid_namespace.h>
50#include <linux/smp.h>
51#include <linux/threads.h>
52#include <linux/timer.h>
53#include <linux/rcupdate.h>
54#include <linux/cpu.h>
55#include <linux/cpuset.h>
56#include <linux/percpu.h>
57#include <linux/proc_fs.h>
58#include <linux/seq_file.h>
59#include <linux/sysctl.h>
60#include <linux/syscalls.h>
61#include <linux/times.h>
62#include <linux/tsacct_kern.h>
63#include <linux/kprobes.h>
64#include <linux/delayacct.h>
65#include <linux/unistd.h>
66#include <linux/pagemap.h>
67#include <linux/hrtimer.h>
68#include <linux/tick.h>
69#include <linux/debugfs.h>
70#include <linux/ctype.h>
71#include <linux/ftrace.h>
72#include <linux/slab.h>
73#include <linux/init_task.h>
74#include <linux/binfmts.h>
75#include <linux/context_tracking.h>
76#include <linux/compiler.h>
77
78#include <asm/switch_to.h>
79#include <asm/tlb.h>
80#include <asm/irq_regs.h>
81#include <asm/mutex.h>
82#ifdef CONFIG_PARAVIRT
83#include <asm/paravirt.h>
84#endif
85
86#include "sched.h"
87#include "../workqueue_internal.h"
88#include "../smpboot.h"
89
90#define CREATE_TRACE_POINTS
91#include <trace/events/sched.h>
92
93void start_bandwidth_timer(struct hrtimer *period_timer, ktime_t period)
94{
95 unsigned long delta;
96 ktime_t soft, hard, now;
97
98 for (;;) {
99 if (hrtimer_active(period_timer))
100 break;
101
102 now = hrtimer_cb_get_time(period_timer);
103 hrtimer_forward(period_timer, now, period);
104
105 soft = hrtimer_get_softexpires(period_timer);
106 hard = hrtimer_get_expires(period_timer);
107 delta = ktime_to_ns(ktime_sub(hard, soft));
108 __hrtimer_start_range_ns(period_timer, soft, delta,
109 HRTIMER_MODE_ABS_PINNED, 0);
110 }
111}
112
113DEFINE_MUTEX(sched_domains_mutex);
114DEFINE_PER_CPU_SHARED_ALIGNED(struct rq, runqueues);
115
116static void update_rq_clock_task(struct rq *rq, s64 delta);
117
118void update_rq_clock(struct rq *rq)
119{
120 s64 delta;
121
122 if (rq->skip_clock_update > 0)
123 return;
124
125 delta = sched_clock_cpu(cpu_of(rq)) - rq->clock;
126 rq->clock += delta;
127 update_rq_clock_task(rq, delta);
128}
129
130/*
131 * Debugging: various feature bits
132 */
133
134#define SCHED_FEAT(name, enabled) \
135 (1UL << __SCHED_FEAT_##name) * enabled |
136
137const_debug unsigned int sysctl_sched_features =
138#include "features.h"
139 0;
140
141#undef SCHED_FEAT
142
143#ifdef CONFIG_SCHED_DEBUG
144#define SCHED_FEAT(name, enabled) \
145 #name ,
146
147static const char * const sched_feat_names[] = {
148#include "features.h"
149};
150
151#undef SCHED_FEAT
152
153static int sched_feat_show(struct seq_file *m, void *v)
154{
155 int i;
156
157 for (i = 0; i < __SCHED_FEAT_NR; i++) {
158 if (!(sysctl_sched_features & (1UL << i)))
159 seq_puts(m, "NO_");
160 seq_printf(m, "%s ", sched_feat_names[i]);
161 }
162 seq_puts(m, "\n");
163
164 return 0;
165}
166
167#ifdef HAVE_JUMP_LABEL
168
169#define jump_label_key__true STATIC_KEY_INIT_TRUE
170#define jump_label_key__false STATIC_KEY_INIT_FALSE
171
172#define SCHED_FEAT(name, enabled) \
173 jump_label_key__##enabled ,
174
175struct static_key sched_feat_keys[__SCHED_FEAT_NR] = {
176#include "features.h"
177};
178
179#undef SCHED_FEAT
180
181static void sched_feat_disable(int i)
182{
183 if (static_key_enabled(&sched_feat_keys[i]))
184 static_key_slow_dec(&sched_feat_keys[i]);
185}
186
187static void sched_feat_enable(int i)
188{
189 if (!static_key_enabled(&sched_feat_keys[i]))
190 static_key_slow_inc(&sched_feat_keys[i]);
191}
192#else
193static void sched_feat_disable(int i) { };
194static void sched_feat_enable(int i) { };
195#endif /* HAVE_JUMP_LABEL */
196
197static int sched_feat_set(char *cmp)
198{
199 int i;
200 int neg = 0;
201
202 if (strncmp(cmp, "NO_", 3) == 0) {
203 neg = 1;
204 cmp += 3;
205 }
206
207 for (i = 0; i < __SCHED_FEAT_NR; i++) {
208 if (strcmp(cmp, sched_feat_names[i]) == 0) {
209 if (neg) {
210 sysctl_sched_features &= ~(1UL << i);
211 sched_feat_disable(i);
212 } else {
213 sysctl_sched_features |= (1UL << i);
214 sched_feat_enable(i);
215 }
216 break;
217 }
218 }
219
220 return i;
221}
222
223static ssize_t
224sched_feat_write(struct file *filp, const char __user *ubuf,
225 size_t cnt, loff_t *ppos)
226{
227 char buf[64];
228 char *cmp;
229 int i;
230
231 if (cnt > 63)
232 cnt = 63;
233
234 if (copy_from_user(&buf, ubuf, cnt))
235 return -EFAULT;
236
237 buf[cnt] = 0;
238 cmp = strstrip(buf);
239
240 i = sched_feat_set(cmp);
241 if (i == __SCHED_FEAT_NR)
242 return -EINVAL;
243
244 *ppos += cnt;
245
246 return cnt;
247}
248
249static int sched_feat_open(struct inode *inode, struct file *filp)
250{
251 return single_open(filp, sched_feat_show, NULL);
252}
253
254static const struct file_operations sched_feat_fops = {
255 .open = sched_feat_open,
256 .write = sched_feat_write,
257 .read = seq_read,
258 .llseek = seq_lseek,
259 .release = single_release,
260};
261
262static __init int sched_init_debug(void)
263{
264 debugfs_create_file("sched_features", 0644, NULL, NULL,
265 &sched_feat_fops);
266
267 return 0;
268}
269late_initcall(sched_init_debug);
270#endif /* CONFIG_SCHED_DEBUG */
271
272/*
273 * Number of tasks to iterate in a single balance run.
274 * Limited because this is done with IRQs disabled.
275 */
276const_debug unsigned int sysctl_sched_nr_migrate = 32;
277
278/*
279 * period over which we average the RT time consumption, measured
280 * in ms.
281 *
282 * default: 1s
283 */
284const_debug unsigned int sysctl_sched_time_avg = MSEC_PER_SEC;
285
286/*
287 * period over which we measure -rt task cpu usage in us.
288 * default: 1s
289 */
290unsigned int sysctl_sched_rt_period = 1000000;
291
292__read_mostly int scheduler_running;
293
294/*
295 * part of the period that we allow rt tasks to run in us.
296 * default: 0.95s
297 */
298int sysctl_sched_rt_runtime = 950000;
299
300/*
301 * __task_rq_lock - lock the rq @p resides on.
302 */
303static inline struct rq *__task_rq_lock(struct task_struct *p)
304 __acquires(rq->lock)
305{
306 struct rq *rq;
307
308 lockdep_assert_held(&p->pi_lock);
309
310 for (;;) {
311 rq = task_rq(p);
312 raw_spin_lock(&rq->lock);
313 if (likely(rq == task_rq(p)))
314 return rq;
315 raw_spin_unlock(&rq->lock);
316 }
317}
318
319/*
320 * task_rq_lock - lock p->pi_lock and lock the rq @p resides on.
321 */
322static struct rq *task_rq_lock(struct task_struct *p, unsigned long *flags)
323 __acquires(p->pi_lock)
324 __acquires(rq->lock)
325{
326 struct rq *rq;
327
328 for (;;) {
329 raw_spin_lock_irqsave(&p->pi_lock, *flags);
330 rq = task_rq(p);
331 raw_spin_lock(&rq->lock);
332 if (likely(rq == task_rq(p)))
333 return rq;
334 raw_spin_unlock(&rq->lock);
335 raw_spin_unlock_irqrestore(&p->pi_lock, *flags);
336 }
337}
338
339static void __task_rq_unlock(struct rq *rq)
340 __releases(rq->lock)
341{
342 raw_spin_unlock(&rq->lock);
343}
344
345static inline void
346task_rq_unlock(struct rq *rq, struct task_struct *p, unsigned long *flags)
347 __releases(rq->lock)
348 __releases(p->pi_lock)
349{
350 raw_spin_unlock(&rq->lock);
351 raw_spin_unlock_irqrestore(&p->pi_lock, *flags);
352}
353
354/*
355 * this_rq_lock - lock this runqueue and disable interrupts.
356 */
357static struct rq *this_rq_lock(void)
358 __acquires(rq->lock)
359{
360 struct rq *rq;
361
362 local_irq_disable();
363 rq = this_rq();
364 raw_spin_lock(&rq->lock);
365
366 return rq;
367}
368
369#ifdef CONFIG_SCHED_HRTICK
370/*
371 * Use HR-timers to deliver accurate preemption points.
372 */
373
374static void hrtick_clear(struct rq *rq)
375{
376 if (hrtimer_active(&rq->hrtick_timer))
377 hrtimer_cancel(&rq->hrtick_timer);
378}
379
380/*
381 * High-resolution timer tick.
382 * Runs from hardirq context with interrupts disabled.
383 */
384static enum hrtimer_restart hrtick(struct hrtimer *timer)
385{
386 struct rq *rq = container_of(timer, struct rq, hrtick_timer);
387
388 WARN_ON_ONCE(cpu_of(rq) != smp_processor_id());
389
390 raw_spin_lock(&rq->lock);
391 update_rq_clock(rq);
392 rq->curr->sched_class->task_tick(rq, rq->curr, 1);
393 raw_spin_unlock(&rq->lock);
394
395 return HRTIMER_NORESTART;
396}
397
398#ifdef CONFIG_SMP
399
400static int __hrtick_restart(struct rq *rq)
401{
402 struct hrtimer *timer = &rq->hrtick_timer;
403 ktime_t time = hrtimer_get_softexpires(timer);
404
405 return __hrtimer_start_range_ns(timer, time, 0, HRTIMER_MODE_ABS_PINNED, 0);
406}
407
408/*
409 * called from hardirq (IPI) context
410 */
411static void __hrtick_start(void *arg)
412{
413 struct rq *rq = arg;
414
415 raw_spin_lock(&rq->lock);
416 __hrtick_restart(rq);
417 rq->hrtick_csd_pending = 0;
418 raw_spin_unlock(&rq->lock);
419}
420
421/*
422 * Called to set the hrtick timer state.
423 *
424 * called with rq->lock held and irqs disabled
425 */
426void hrtick_start(struct rq *rq, u64 delay)
427{
428 struct hrtimer *timer = &rq->hrtick_timer;
429 ktime_t time = ktime_add_ns(timer->base->get_time(), delay);
430
431 hrtimer_set_expires(timer, time);
432
433 if (rq == this_rq()) {
434 __hrtick_restart(rq);
435 } else if (!rq->hrtick_csd_pending) {
436 smp_call_function_single_async(cpu_of(rq), &rq->hrtick_csd);
437 rq->hrtick_csd_pending = 1;
438 }
439}
440
441static int
442hotplug_hrtick(struct notifier_block *nfb, unsigned long action, void *hcpu)
443{
444 int cpu = (int)(long)hcpu;
445
446 switch (action) {
447 case CPU_UP_CANCELED:
448 case CPU_UP_CANCELED_FROZEN:
449 case CPU_DOWN_PREPARE:
450 case CPU_DOWN_PREPARE_FROZEN:
451 case CPU_DEAD:
452 case CPU_DEAD_FROZEN:
453 hrtick_clear(cpu_rq(cpu));
454 return NOTIFY_OK;
455 }
456
457 return NOTIFY_DONE;
458}
459
460static __init void init_hrtick(void)
461{
462 hotcpu_notifier(hotplug_hrtick, 0);
463}
464#else
465/*
466 * Called to set the hrtick timer state.
467 *
468 * called with rq->lock held and irqs disabled
469 */
470void hrtick_start(struct rq *rq, u64 delay)
471{
472 __hrtimer_start_range_ns(&rq->hrtick_timer, ns_to_ktime(delay), 0,
473 HRTIMER_MODE_REL_PINNED, 0);
474}
475
476static inline void init_hrtick(void)
477{
478}
479#endif /* CONFIG_SMP */
480
481static void init_rq_hrtick(struct rq *rq)
482{
483#ifdef CONFIG_SMP
484 rq->hrtick_csd_pending = 0;
485
486 rq->hrtick_csd.flags = 0;
487 rq->hrtick_csd.func = __hrtick_start;
488 rq->hrtick_csd.info = rq;
489#endif
490
491 hrtimer_init(&rq->hrtick_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
492 rq->hrtick_timer.function = hrtick;
493}
494#else /* CONFIG_SCHED_HRTICK */
495static inline void hrtick_clear(struct rq *rq)
496{
497}
498
499static inline void init_rq_hrtick(struct rq *rq)
500{
501}
502
503static inline void init_hrtick(void)
504{
505}
506#endif /* CONFIG_SCHED_HRTICK */
507
508/*
509 * resched_task - mark a task 'to be rescheduled now'.
510 *
511 * On UP this means the setting of the need_resched flag, on SMP it
512 * might also involve a cross-CPU call to trigger the scheduler on
513 * the target CPU.
514 */
515void resched_task(struct task_struct *p)
516{
517 int cpu;
518
519 lockdep_assert_held(&task_rq(p)->lock);
520
521 if (test_tsk_need_resched(p))
522 return;
523
524 set_tsk_need_resched(p);
525
526 cpu = task_cpu(p);
527 if (cpu == smp_processor_id()) {
528 set_preempt_need_resched();
529 return;
530 }
531
532 /* NEED_RESCHED must be visible before we test polling */
533 smp_mb();
534 if (!tsk_is_polling(p))
535 smp_send_reschedule(cpu);
536}
537
538void resched_cpu(int cpu)
539{
540 struct rq *rq = cpu_rq(cpu);
541 unsigned long flags;
542
543 if (!raw_spin_trylock_irqsave(&rq->lock, flags))
544 return;
545 resched_task(cpu_curr(cpu));
546 raw_spin_unlock_irqrestore(&rq->lock, flags);
547}
548
549#ifdef CONFIG_SMP
550#ifdef CONFIG_NO_HZ_COMMON
551/*
552 * In the semi idle case, use the nearest busy cpu for migrating timers
553 * from an idle cpu. This is good for power-savings.
554 *
555 * We don't do similar optimization for completely idle system, as
556 * selecting an idle cpu will add more delays to the timers than intended
557 * (as that cpu's timer base may not be uptodate wrt jiffies etc).
558 */
559int get_nohz_timer_target(int pinned)
560{
561 int cpu = smp_processor_id();
562 int i;
563 struct sched_domain *sd;
564
565 if (pinned || !get_sysctl_timer_migration() || !idle_cpu(cpu))
566 return cpu;
567
568 rcu_read_lock();
569 for_each_domain(cpu, sd) {
570 for_each_cpu(i, sched_domain_span(sd)) {
571 if (!idle_cpu(i)) {
572 cpu = i;
573 goto unlock;
574 }
575 }
576 }
577unlock:
578 rcu_read_unlock();
579 return cpu;
580}
581/*
582 * When add_timer_on() enqueues a timer into the timer wheel of an
583 * idle CPU then this timer might expire before the next timer event
584 * which is scheduled to wake up that CPU. In case of a completely
585 * idle system the next event might even be infinite time into the
586 * future. wake_up_idle_cpu() ensures that the CPU is woken up and
587 * leaves the inner idle loop so the newly added timer is taken into
588 * account when the CPU goes back to idle and evaluates the timer
589 * wheel for the next timer event.
590 */
591static void wake_up_idle_cpu(int cpu)
592{
593 struct rq *rq = cpu_rq(cpu);
594
595 if (cpu == smp_processor_id())
596 return;
597
598 /*
599 * This is safe, as this function is called with the timer
600 * wheel base lock of (cpu) held. When the CPU is on the way
601 * to idle and has not yet set rq->curr to idle then it will
602 * be serialized on the timer wheel base lock and take the new
603 * timer into account automatically.
604 */
605 if (rq->curr != rq->idle)
606 return;
607
608 /*
609 * We can set TIF_RESCHED on the idle task of the other CPU
610 * lockless. The worst case is that the other CPU runs the
611 * idle task through an additional NOOP schedule()
612 */
613 set_tsk_need_resched(rq->idle);
614
615 /* NEED_RESCHED must be visible before we test polling */
616 smp_mb();
617 if (!tsk_is_polling(rq->idle))
618 smp_send_reschedule(cpu);
619}
620
621static bool wake_up_full_nohz_cpu(int cpu)
622{
623 if (tick_nohz_full_cpu(cpu)) {
624 if (cpu != smp_processor_id() ||
625 tick_nohz_tick_stopped())
626 smp_send_reschedule(cpu);
627 return true;
628 }
629
630 return false;
631}
632
633void wake_up_nohz_cpu(int cpu)
634{
635 if (!wake_up_full_nohz_cpu(cpu))
636 wake_up_idle_cpu(cpu);
637}
638
639static inline bool got_nohz_idle_kick(void)
640{
641 int cpu = smp_processor_id();
642
643 if (!test_bit(NOHZ_BALANCE_KICK, nohz_flags(cpu)))
644 return false;
645
646 if (idle_cpu(cpu) && !need_resched())
647 return true;
648
649 /*
650 * We can't run Idle Load Balance on this CPU for this time so we
651 * cancel it and clear NOHZ_BALANCE_KICK
652 */
653 clear_bit(NOHZ_BALANCE_KICK, nohz_flags(cpu));
654 return false;
655}
656
657#else /* CONFIG_NO_HZ_COMMON */
658
659static inline bool got_nohz_idle_kick(void)
660{
661 return false;
662}
663
664#endif /* CONFIG_NO_HZ_COMMON */
665
666#ifdef CONFIG_NO_HZ_FULL
667bool sched_can_stop_tick(void)
668{
669 struct rq *rq;
670
671 rq = this_rq();
672
673 /* Make sure rq->nr_running update is visible after the IPI */
674 smp_rmb();
675
676 /* More than one running task need preemption */
677 if (rq->nr_running > 1)
678 return false;
679
680 return true;
681}
682#endif /* CONFIG_NO_HZ_FULL */
683
684void sched_avg_update(struct rq *rq)
685{
686 s64 period = sched_avg_period();
687
688 while ((s64)(rq_clock(rq) - rq->age_stamp) > period) {
689 /*
690 * Inline assembly required to prevent the compiler
691 * optimising this loop into a divmod call.
692 * See __iter_div_u64_rem() for another example of this.
693 */
694 asm("" : "+rm" (rq->age_stamp));
695 rq->age_stamp += period;
696 rq->rt_avg /= 2;
697 }
698}
699
700#endif /* CONFIG_SMP */
701
702#if defined(CONFIG_RT_GROUP_SCHED) || (defined(CONFIG_FAIR_GROUP_SCHED) && \
703 (defined(CONFIG_SMP) || defined(CONFIG_CFS_BANDWIDTH)))
704/*
705 * Iterate task_group tree rooted at *from, calling @down when first entering a
706 * node and @up when leaving it for the final time.
707 *
708 * Caller must hold rcu_lock or sufficient equivalent.
709 */
710int walk_tg_tree_from(struct task_group *from,
711 tg_visitor down, tg_visitor up, void *data)
712{
713 struct task_group *parent, *child;
714 int ret;
715
716 parent = from;
717
718down:
719 ret = (*down)(parent, data);
720 if (ret)
721 goto out;
722 list_for_each_entry_rcu(child, &parent->children, siblings) {
723 parent = child;
724 goto down;
725
726up:
727 continue;
728 }
729 ret = (*up)(parent, data);
730 if (ret || parent == from)
731 goto out;
732
733 child = parent;
734 parent = parent->parent;
735 if (parent)
736 goto up;
737out:
738 return ret;
739}
740
741int tg_nop(struct task_group *tg, void *data)
742{
743 return 0;
744}
745#endif
746
747static void set_load_weight(struct task_struct *p)
748{
749 int prio = p->static_prio - MAX_RT_PRIO;
750 struct load_weight *load = &p->se.load;
751
752 /*
753 * SCHED_IDLE tasks get minimal weight:
754 */
755 if (p->policy == SCHED_IDLE) {
756 load->weight = scale_load(WEIGHT_IDLEPRIO);
757 load->inv_weight = WMULT_IDLEPRIO;
758 return;
759 }
760
761 load->weight = scale_load(prio_to_weight[prio]);
762 load->inv_weight = prio_to_wmult[prio];
763}
764
765static void enqueue_task(struct rq *rq, struct task_struct *p, int flags)
766{
767 update_rq_clock(rq);
768 sched_info_queued(rq, p);
769 p->sched_class->enqueue_task(rq, p, flags);
770}
771
772static void dequeue_task(struct rq *rq, struct task_struct *p, int flags)
773{
774 update_rq_clock(rq);
775 sched_info_dequeued(rq, p);
776 p->sched_class->dequeue_task(rq, p, flags);
777}
778
779void activate_task(struct rq *rq, struct task_struct *p, int flags)
780{
781 if (task_contributes_to_load(p))
782 rq->nr_uninterruptible--;
783
784 enqueue_task(rq, p, flags);
785}
786
787void deactivate_task(struct rq *rq, struct task_struct *p, int flags)
788{
789 if (task_contributes_to_load(p))
790 rq->nr_uninterruptible++;
791
792 dequeue_task(rq, p, flags);
793}
794
795static void update_rq_clock_task(struct rq *rq, s64 delta)
796{
797/*
798 * In theory, the compile should just see 0 here, and optimize out the call
799 * to sched_rt_avg_update. But I don't trust it...
800 */
801#if defined(CONFIG_IRQ_TIME_ACCOUNTING) || defined(CONFIG_PARAVIRT_TIME_ACCOUNTING)
802 s64 steal = 0, irq_delta = 0;
803#endif
804#ifdef CONFIG_IRQ_TIME_ACCOUNTING
805 irq_delta = irq_time_read(cpu_of(rq)) - rq->prev_irq_time;
806
807 /*
808 * Since irq_time is only updated on {soft,}irq_exit, we might run into
809 * this case when a previous update_rq_clock() happened inside a
810 * {soft,}irq region.
811 *
812 * When this happens, we stop ->clock_task and only update the
813 * prev_irq_time stamp to account for the part that fit, so that a next
814 * update will consume the rest. This ensures ->clock_task is
815 * monotonic.
816 *
817 * It does however cause some slight miss-attribution of {soft,}irq
818 * time, a more accurate solution would be to update the irq_time using
819 * the current rq->clock timestamp, except that would require using
820 * atomic ops.
821 */
822 if (irq_delta > delta)
823 irq_delta = delta;
824
825 rq->prev_irq_time += irq_delta;
826 delta -= irq_delta;
827#endif
828#ifdef CONFIG_PARAVIRT_TIME_ACCOUNTING
829 if (static_key_false((¶virt_steal_rq_enabled))) {
830 steal = paravirt_steal_clock(cpu_of(rq));
831 steal -= rq->prev_steal_time_rq;
832
833 if (unlikely(steal > delta))
834 steal = delta;
835
836 rq->prev_steal_time_rq += steal;
837 delta -= steal;
838 }
839#endif
840
841 rq->clock_task += delta;
842
843#if defined(CONFIG_IRQ_TIME_ACCOUNTING) || defined(CONFIG_PARAVIRT_TIME_ACCOUNTING)
844 if ((irq_delta + steal) && sched_feat(NONTASK_POWER))
845 sched_rt_avg_update(rq, irq_delta + steal);
846#endif
847}
848
849void sched_set_stop_task(int cpu, struct task_struct *stop)
850{
851 struct sched_param param = { .sched_priority = MAX_RT_PRIO - 1 };
852 struct task_struct *old_stop = cpu_rq(cpu)->stop;
853
854 if (stop) {
855 /*
856 * Make it appear like a SCHED_FIFO task, its something
857 * userspace knows about and won't get confused about.
858 *
859 * Also, it will make PI more or less work without too
860 * much confusion -- but then, stop work should not
861 * rely on PI working anyway.
862 */
863 sched_setscheduler_nocheck(stop, SCHED_FIFO, ¶m);
864
865 stop->sched_class = &stop_sched_class;
866 }
867
868 cpu_rq(cpu)->stop = stop;
869
870 if (old_stop) {
871 /*
872 * Reset it back to a normal scheduling class so that
873 * it can die in pieces.
874 */
875 old_stop->sched_class = &rt_sched_class;
876 }
877}
878
879/*
880 * __normal_prio - return the priority that is based on the static prio
881 */
882static inline int __normal_prio(struct task_struct *p)
883{
884 return p->static_prio;
885}
886
887/*
888 * Calculate the expected normal priority: i.e. priority
889 * without taking RT-inheritance into account. Might be
890 * boosted by interactivity modifiers. Changes upon fork,
891 * setprio syscalls, and whenever the interactivity
892 * estimator recalculates.
893 */
894static inline int normal_prio(struct task_struct *p)
895{
896 int prio;
897
898 if (task_has_dl_policy(p))
899 prio = MAX_DL_PRIO-1;
900 else if (task_has_rt_policy(p))
901 prio = MAX_RT_PRIO-1 - p->rt_priority;
902 else
903 prio = __normal_prio(p);
904 return prio;
905}
906
907/*
908 * Calculate the current priority, i.e. the priority
909 * taken into account by the scheduler. This value might
910 * be boosted by RT tasks, or might be boosted by
911 * interactivity modifiers. Will be RT if the task got
912 * RT-boosted. If not then it returns p->normal_prio.
913 */
914static int effective_prio(struct task_struct *p)
915{
916 p->normal_prio = normal_prio(p);
917 /*
918 * If we are RT tasks or we were boosted to RT priority,
919 * keep the priority unchanged. Otherwise, update priority
920 * to the normal priority:
921 */
922 if (!rt_prio(p->prio))
923 return p->normal_prio;
924 return p->prio;
925}
926
927/**
928 * task_curr - is this task currently executing on a CPU?
929 * @p: the task in question.
930 *
931 * Return: 1 if the task is currently executing. 0 otherwise.
932 */
933inline int task_curr(const struct task_struct *p)
934{
935 return cpu_curr(task_cpu(p)) == p;
936}
937
938static inline void check_class_changed(struct rq *rq, struct task_struct *p,
939 const struct sched_class *prev_class,
940 int oldprio)
941{
942 if (prev_class != p->sched_class) {
943 if (prev_class->switched_from)
944 prev_class->switched_from(rq, p);
945 p->sched_class->switched_to(rq, p);
946 } else if (oldprio != p->prio || dl_task(p))
947 p->sched_class->prio_changed(rq, p, oldprio);
948}
949
950void check_preempt_curr(struct rq *rq, struct task_struct *p, int flags)
951{
952 const struct sched_class *class;
953
954 if (p->sched_class == rq->curr->sched_class) {
955 rq->curr->sched_class->check_preempt_curr(rq, p, flags);
956 } else {
957 for_each_class(class) {
958 if (class == rq->curr->sched_class)
959 break;
960 if (class == p->sched_class) {
961 resched_task(rq->curr);
962 break;
963 }
964 }
965 }
966
967 /*
968 * A queue event has occurred, and we're going to schedule. In
969 * this case, we can save a useless back to back clock update.
970 */
971 if (rq->curr->on_rq && test_tsk_need_resched(rq->curr))
972 rq->skip_clock_update = 1;
973}
974
975#ifdef CONFIG_SMP
976void set_task_cpu(struct task_struct *p, unsigned int new_cpu)
977{
978#ifdef CONFIG_SCHED_DEBUG
979 /*
980 * We should never call set_task_cpu() on a blocked task,
981 * ttwu() will sort out the placement.
982 */
983 WARN_ON_ONCE(p->state != TASK_RUNNING && p->state != TASK_WAKING &&
984 !(task_preempt_count(p) & PREEMPT_ACTIVE));
985
986#ifdef CONFIG_LOCKDEP
987 /*
988 * The caller should hold either p->pi_lock or rq->lock, when changing
989 * a task's CPU. ->pi_lock for waking tasks, rq->lock for runnable tasks.
990 *
991 * sched_move_task() holds both and thus holding either pins the cgroup,
992 * see task_group().
993 *
994 * Furthermore, all task_rq users should acquire both locks, see
995 * task_rq_lock().
996 */
997 WARN_ON_ONCE(debug_locks && !(lockdep_is_held(&p->pi_lock) ||
998 lockdep_is_held(&task_rq(p)->lock)));
999#endif
1000#endif
1001
1002 trace_sched_migrate_task(p, new_cpu);
1003
1004 if (task_cpu(p) != new_cpu) {
1005 if (p->sched_class->migrate_task_rq)
1006 p->sched_class->migrate_task_rq(p, new_cpu);
1007 p->se.nr_migrations++;
1008 perf_sw_event(PERF_COUNT_SW_CPU_MIGRATIONS, 1, NULL, 0);
1009 }
1010
1011 __set_task_cpu(p, new_cpu);
1012}
1013
1014static void __migrate_swap_task(struct task_struct *p, int cpu)
1015{
1016 if (p->on_rq) {
1017 struct rq *src_rq, *dst_rq;
1018
1019 src_rq = task_rq(p);
1020 dst_rq = cpu_rq(cpu);
1021
1022 deactivate_task(src_rq, p, 0);
1023 set_task_cpu(p, cpu);
1024 activate_task(dst_rq, p, 0);
1025 check_preempt_curr(dst_rq, p, 0);
1026 } else {
1027 /*
1028 * Task isn't running anymore; make it appear like we migrated
1029 * it before it went to sleep. This means on wakeup we make the
1030 * previous cpu our targer instead of where it really is.
1031 */
1032 p->wake_cpu = cpu;
1033 }
1034}
1035
1036struct migration_swap_arg {
1037 struct task_struct *src_task, *dst_task;
1038 int src_cpu, dst_cpu;
1039};
1040
1041static int migrate_swap_stop(void *data)
1042{
1043 struct migration_swap_arg *arg = data;
1044 struct rq *src_rq, *dst_rq;
1045 int ret = -EAGAIN;
1046
1047 src_rq = cpu_rq(arg->src_cpu);
1048 dst_rq = cpu_rq(arg->dst_cpu);
1049
1050 double_raw_lock(&arg->src_task->pi_lock,
1051 &arg->dst_task->pi_lock);
1052 double_rq_lock(src_rq, dst_rq);
1053 if (task_cpu(arg->dst_task) != arg->dst_cpu)
1054 goto unlock;
1055
1056 if (task_cpu(arg->src_task) != arg->src_cpu)
1057 goto unlock;
1058
1059 if (!cpumask_test_cpu(arg->dst_cpu, tsk_cpus_allowed(arg->src_task)))
1060 goto unlock;
1061
1062 if (!cpumask_test_cpu(arg->src_cpu, tsk_cpus_allowed(arg->dst_task)))
1063 goto unlock;
1064
1065 __migrate_swap_task(arg->src_task, arg->dst_cpu);
1066 __migrate_swap_task(arg->dst_task, arg->src_cpu);
1067
1068 ret = 0;
1069
1070unlock:
1071 double_rq_unlock(src_rq, dst_rq);
1072 raw_spin_unlock(&arg->dst_task->pi_lock);
1073 raw_spin_unlock(&arg->src_task->pi_lock);
1074
1075 return ret;
1076}
1077
1078/*
1079 * Cross migrate two tasks
1080 */
1081int migrate_swap(struct task_struct *cur, struct task_struct *p)
1082{
1083 struct migration_swap_arg arg;
1084 int ret = -EINVAL;
1085
1086 arg = (struct migration_swap_arg){
1087 .src_task = cur,
1088 .src_cpu = task_cpu(cur),
1089 .dst_task = p,
1090 .dst_cpu = task_cpu(p),
1091 };
1092
1093 if (arg.src_cpu == arg.dst_cpu)
1094 goto out;
1095
1096 /*
1097 * These three tests are all lockless; this is OK since all of them
1098 * will be re-checked with proper locks held further down the line.
1099 */
1100 if (!cpu_active(arg.src_cpu) || !cpu_active(arg.dst_cpu))
1101 goto out;
1102
1103 if (!cpumask_test_cpu(arg.dst_cpu, tsk_cpus_allowed(arg.src_task)))
1104 goto out;
1105
1106 if (!cpumask_test_cpu(arg.src_cpu, tsk_cpus_allowed(arg.dst_task)))
1107 goto out;
1108
1109 trace_sched_swap_numa(cur, arg.src_cpu, p, arg.dst_cpu);
1110 ret = stop_two_cpus(arg.dst_cpu, arg.src_cpu, migrate_swap_stop, &arg);
1111
1112out:
1113 return ret;
1114}
1115
1116struct migration_arg {
1117 struct task_struct *task;
1118 int dest_cpu;
1119};
1120
1121static int migration_cpu_stop(void *data);
1122
1123/*
1124 * wait_task_inactive - wait for a thread to unschedule.
1125 *
1126 * If @match_state is nonzero, it's the @p->state value just checked and
1127 * not expected to change. If it changes, i.e. @p might have woken up,
1128 * then return zero. When we succeed in waiting for @p to be off its CPU,
1129 * we return a positive number (its total switch count). If a second call
1130 * a short while later returns the same number, the caller can be sure that
1131 * @p has remained unscheduled the whole time.
1132 *
1133 * The caller must ensure that the task *will* unschedule sometime soon,
1134 * else this function might spin for a *long* time. This function can't
1135 * be called with interrupts off, or it may introduce deadlock with
1136 * smp_call_function() if an IPI is sent by the same process we are
1137 * waiting to become inactive.
1138 */
1139unsigned long wait_task_inactive(struct task_struct *p, long match_state)
1140{
1141 unsigned long flags;
1142 int running, on_rq;
1143 unsigned long ncsw;
1144 struct rq *rq;
1145
1146 for (;;) {
1147 /*
1148 * We do the initial early heuristics without holding
1149 * any task-queue locks at all. We'll only try to get
1150 * the runqueue lock when things look like they will
1151 * work out!
1152 */
1153 rq = task_rq(p);
1154
1155 /*
1156 * If the task is actively running on another CPU
1157 * still, just relax and busy-wait without holding
1158 * any locks.
1159 *
1160 * NOTE! Since we don't hold any locks, it's not
1161 * even sure that "rq" stays as the right runqueue!
1162 * But we don't care, since "task_running()" will
1163 * return false if the runqueue has changed and p
1164 * is actually now running somewhere else!
1165 */
1166 while (task_running(rq, p)) {
1167 if (match_state && unlikely(p->state != match_state))
1168 return 0;
1169 cpu_relax();
1170 }
1171
1172 /*
1173 * Ok, time to look more closely! We need the rq
1174 * lock now, to be *sure*. If we're wrong, we'll
1175 * just go back and repeat.
1176 */
1177 rq = task_rq_lock(p, &flags);
1178 trace_sched_wait_task(p);
1179 running = task_running(rq, p);
1180 on_rq = p->on_rq;
1181 ncsw = 0;
1182 if (!match_state || p->state == match_state)
1183 ncsw = p->nvcsw | LONG_MIN; /* sets MSB */
1184 task_rq_unlock(rq, p, &flags);
1185
1186 /*
1187 * If it changed from the expected state, bail out now.
1188 */
1189 if (unlikely(!ncsw))
1190 break;
1191
1192 /*
1193 * Was it really running after all now that we
1194 * checked with the proper locks actually held?
1195 *
1196 * Oops. Go back and try again..
1197 */
1198 if (unlikely(running)) {
1199 cpu_relax();
1200 continue;
1201 }
1202
1203 /*
1204 * It's not enough that it's not actively running,
1205 * it must be off the runqueue _entirely_, and not
1206 * preempted!
1207 *
1208 * So if it was still runnable (but just not actively
1209 * running right now), it's preempted, and we should
1210 * yield - it could be a while.
1211 */
1212 if (unlikely(on_rq)) {
1213 ktime_t to = ktime_set(0, NSEC_PER_SEC/HZ);
1214
1215 set_current_state(TASK_UNINTERRUPTIBLE);
1216 schedule_hrtimeout(&to, HRTIMER_MODE_REL);
1217 continue;
1218 }
1219
1220 /*
1221 * Ahh, all good. It wasn't running, and it wasn't
1222 * runnable, which means that it will never become
1223 * running in the future either. We're all done!
1224 */
1225 break;
1226 }
1227
1228 return ncsw;
1229}
1230
1231/***
1232 * kick_process - kick a running thread to enter/exit the kernel
1233 * @p: the to-be-kicked thread
1234 *
1235 * Cause a process which is running on another CPU to enter
1236 * kernel-mode, without any delay. (to get signals handled.)
1237 *
1238 * NOTE: this function doesn't have to take the runqueue lock,
1239 * because all it wants to ensure is that the remote task enters
1240 * the kernel. If the IPI races and the task has been migrated
1241 * to another CPU then no harm is done and the purpose has been
1242 * achieved as well.
1243 */
1244void kick_process(struct task_struct *p)
1245{
1246 int cpu;
1247
1248 preempt_disable();
1249 cpu = task_cpu(p);
1250 if ((cpu != smp_processor_id()) && task_curr(p))
1251 smp_send_reschedule(cpu);
1252 preempt_enable();
1253}
1254EXPORT_SYMBOL_GPL(kick_process);
1255#endif /* CONFIG_SMP */
1256
1257#ifdef CONFIG_SMP
1258/*
1259 * ->cpus_allowed is protected by both rq->lock and p->pi_lock
1260 */
1261static int select_fallback_rq(int cpu, struct task_struct *p)
1262{
1263 int nid = cpu_to_node(cpu);
1264 const struct cpumask *nodemask = NULL;
1265 enum { cpuset, possible, fail } state = cpuset;
1266 int dest_cpu;
1267
1268 /*
1269 * If the node that the cpu is on has been offlined, cpu_to_node()
1270 * will return -1. There is no cpu on the node, and we should
1271 * select the cpu on the other node.
1272 */
1273 if (nid != -1) {
1274 nodemask = cpumask_of_node(nid);
1275
1276 /* Look for allowed, online CPU in same node. */
1277 for_each_cpu(dest_cpu, nodemask) {
1278 if (!cpu_online(dest_cpu))
1279 continue;
1280 if (!cpu_active(dest_cpu))
1281 continue;
1282 if (cpumask_test_cpu(dest_cpu, tsk_cpus_allowed(p)))
1283 return dest_cpu;
1284 }
1285 }
1286
1287 for (;;) {
1288 /* Any allowed, online CPU? */
1289 for_each_cpu(dest_cpu, tsk_cpus_allowed(p)) {
1290 if (!cpu_online(dest_cpu))
1291 continue;
1292 if (!cpu_active(dest_cpu))
1293 continue;
1294 goto out;
1295 }
1296
1297 switch (state) {
1298 case cpuset:
1299 /* No more Mr. Nice Guy. */
1300 cpuset_cpus_allowed_fallback(p);
1301 state = possible;
1302 break;
1303
1304 case possible:
1305 do_set_cpus_allowed(p, cpu_possible_mask);
1306 state = fail;
1307 break;
1308
1309 case fail:
1310 BUG();
1311 break;
1312 }
1313 }
1314
1315out:
1316 if (state != cpuset) {
1317 /*
1318 * Don't tell them about moving exiting tasks or
1319 * kernel threads (both mm NULL), since they never
1320 * leave kernel.
1321 */
1322 if (p->mm && printk_ratelimit()) {
1323 printk_sched("process %d (%s) no longer affine to cpu%d\n",
1324 task_pid_nr(p), p->comm, cpu);
1325 }
1326 }
1327
1328 return dest_cpu;
1329}
1330
1331/*
1332 * The caller (fork, wakeup) owns p->pi_lock, ->cpus_allowed is stable.
1333 */
1334static inline
1335int select_task_rq(struct task_struct *p, int cpu, int sd_flags, int wake_flags)
1336{
1337 cpu = p->sched_class->select_task_rq(p, cpu, sd_flags, wake_flags);
1338
1339 /*
1340 * In order not to call set_task_cpu() on a blocking task we need
1341 * to rely on ttwu() to place the task on a valid ->cpus_allowed
1342 * cpu.
1343 *
1344 * Since this is common to all placement strategies, this lives here.
1345 *
1346 * [ this allows ->select_task() to simply return task_cpu(p) and
1347 * not worry about this generic constraint ]
1348 */
1349 if (unlikely(!cpumask_test_cpu(cpu, tsk_cpus_allowed(p)) ||
1350 !cpu_online(cpu)))
1351 cpu = select_fallback_rq(task_cpu(p), p);
1352
1353 return cpu;
1354}
1355
1356static void update_avg(u64 *avg, u64 sample)
1357{
1358 s64 diff = sample - *avg;
1359 *avg += diff >> 3;
1360}
1361#endif
1362
1363static void
1364ttwu_stat(struct task_struct *p, int cpu, int wake_flags)
1365{
1366#ifdef CONFIG_SCHEDSTATS
1367 struct rq *rq = this_rq();
1368
1369#ifdef CONFIG_SMP
1370 int this_cpu = smp_processor_id();
1371
1372 if (cpu == this_cpu) {
1373 schedstat_inc(rq, ttwu_local);
1374 schedstat_inc(p, se.statistics.nr_wakeups_local);
1375 } else {
1376 struct sched_domain *sd;
1377
1378 schedstat_inc(p, se.statistics.nr_wakeups_remote);
1379 rcu_read_lock();
1380 for_each_domain(this_cpu, sd) {
1381 if (cpumask_test_cpu(cpu, sched_domain_span(sd))) {
1382 schedstat_inc(sd, ttwu_wake_remote);
1383 break;
1384 }
1385 }
1386 rcu_read_unlock();
1387 }
1388
1389 if (wake_flags & WF_MIGRATED)
1390 schedstat_inc(p, se.statistics.nr_wakeups_migrate);
1391
1392#endif /* CONFIG_SMP */
1393
1394 schedstat_inc(rq, ttwu_count);
1395 schedstat_inc(p, se.statistics.nr_wakeups);
1396
1397 if (wake_flags & WF_SYNC)
1398 schedstat_inc(p, se.statistics.nr_wakeups_sync);
1399
1400#endif /* CONFIG_SCHEDSTATS */
1401}
1402
1403static void ttwu_activate(struct rq *rq, struct task_struct *p, int en_flags)
1404{
1405 activate_task(rq, p, en_flags);
1406 p->on_rq = 1;
1407
1408 /* if a worker is waking up, notify workqueue */
1409 if (p->flags & PF_WQ_WORKER)
1410 wq_worker_waking_up(p, cpu_of(rq));
1411}
1412
1413/*
1414 * Mark the task runnable and perform wakeup-preemption.
1415 */
1416static void
1417ttwu_do_wakeup(struct rq *rq, struct task_struct *p, int wake_flags)
1418{
1419 check_preempt_curr(rq, p, wake_flags);
1420 trace_sched_wakeup(p, true);
1421
1422 p->state = TASK_RUNNING;
1423#ifdef CONFIG_SMP
1424 if (p->sched_class->task_woken)
1425 p->sched_class->task_woken(rq, p);
1426
1427 if (rq->idle_stamp) {
1428 u64 delta = rq_clock(rq) - rq->idle_stamp;
1429 u64 max = 2*rq->max_idle_balance_cost;
1430
1431 update_avg(&rq->avg_idle, delta);
1432
1433 if (rq->avg_idle > max)
1434 rq->avg_idle = max;
1435
1436 rq->idle_stamp = 0;
1437 }
1438#endif
1439}
1440
1441static void
1442ttwu_do_activate(struct rq *rq, struct task_struct *p, int wake_flags)
1443{
1444#ifdef CONFIG_SMP
1445 if (p->sched_contributes_to_load)
1446 rq->nr_uninterruptible--;
1447#endif
1448
1449 ttwu_activate(rq, p, ENQUEUE_WAKEUP | ENQUEUE_WAKING);
1450 ttwu_do_wakeup(rq, p, wake_flags);
1451}
1452
1453/*
1454 * Called in case the task @p isn't fully descheduled from its runqueue,
1455 * in this case we must do a remote wakeup. Its a 'light' wakeup though,
1456 * since all we need to do is flip p->state to TASK_RUNNING, since
1457 * the task is still ->on_rq.
1458 */
1459static int ttwu_remote(struct task_struct *p, int wake_flags)
1460{
1461 struct rq *rq;
1462 int ret = 0;
1463
1464 rq = __task_rq_lock(p);
1465 if (p->on_rq) {
1466 /* check_preempt_curr() may use rq clock */
1467 update_rq_clock(rq);
1468 ttwu_do_wakeup(rq, p, wake_flags);
1469 ret = 1;
1470 }
1471 __task_rq_unlock(rq);
1472
1473 return ret;
1474}
1475
1476#ifdef CONFIG_SMP
1477static void sched_ttwu_pending(void)
1478{
1479 struct rq *rq = this_rq();
1480 struct llist_node *llist = llist_del_all(&rq->wake_list);
1481 struct task_struct *p;
1482
1483 raw_spin_lock(&rq->lock);
1484
1485 while (llist) {
1486 p = llist_entry(llist, struct task_struct, wake_entry);
1487 llist = llist_next(llist);
1488 ttwu_do_activate(rq, p, 0);
1489 }
1490
1491 raw_spin_unlock(&rq->lock);
1492}
1493
1494void scheduler_ipi(void)
1495{
1496 /*
1497 * Fold TIF_NEED_RESCHED into the preempt_count; anybody setting
1498 * TIF_NEED_RESCHED remotely (for the first time) will also send
1499 * this IPI.
1500 */
1501 preempt_fold_need_resched();
1502
1503 if (llist_empty(&this_rq()->wake_list)
1504 && !tick_nohz_full_cpu(smp_processor_id())
1505 && !got_nohz_idle_kick())
1506 return;
1507
1508 /*
1509 * Not all reschedule IPI handlers call irq_enter/irq_exit, since
1510 * traditionally all their work was done from the interrupt return
1511 * path. Now that we actually do some work, we need to make sure
1512 * we do call them.
1513 *
1514 * Some archs already do call them, luckily irq_enter/exit nest
1515 * properly.
1516 *
1517 * Arguably we should visit all archs and update all handlers,
1518 * however a fair share of IPIs are still resched only so this would
1519 * somewhat pessimize the simple resched case.
1520 */
1521 irq_enter();
1522 tick_nohz_full_check();
1523 sched_ttwu_pending();
1524
1525 /*
1526 * Check if someone kicked us for doing the nohz idle load balance.
1527 */
1528 if (unlikely(got_nohz_idle_kick())) {
1529 this_rq()->idle_balance = 1;
1530 raise_softirq_irqoff(SCHED_SOFTIRQ);
1531 }
1532 irq_exit();
1533}
1534
1535static void ttwu_queue_remote(struct task_struct *p, int cpu)
1536{
1537 if (llist_add(&p->wake_entry, &cpu_rq(cpu)->wake_list))
1538 smp_send_reschedule(cpu);
1539}
1540
1541bool cpus_share_cache(int this_cpu, int that_cpu)
1542{
1543 return per_cpu(sd_llc_id, this_cpu) == per_cpu(sd_llc_id, that_cpu);
1544}
1545#endif /* CONFIG_SMP */
1546
1547static void ttwu_queue(struct task_struct *p, int cpu)
1548{
1549 struct rq *rq = cpu_rq(cpu);
1550
1551#if defined(CONFIG_SMP)
1552 if (sched_feat(TTWU_QUEUE) && !cpus_share_cache(smp_processor_id(), cpu)) {
1553 sched_clock_cpu(cpu); /* sync clocks x-cpu */
1554 ttwu_queue_remote(p, cpu);
1555 return;
1556 }
1557#endif
1558
1559 raw_spin_lock(&rq->lock);
1560 ttwu_do_activate(rq, p, 0);
1561 raw_spin_unlock(&rq->lock);
1562}
1563
1564/**
1565 * try_to_wake_up - wake up a thread
1566 * @p: the thread to be awakened
1567 * @state: the mask of task states that can be woken
1568 * @wake_flags: wake modifier flags (WF_*)
1569 *
1570 * Put it on the run-queue if it's not already there. The "current"
1571 * thread is always on the run-queue (except when the actual
1572 * re-schedule is in progress), and as such you're allowed to do
1573 * the simpler "current->state = TASK_RUNNING" to mark yourself
1574 * runnable without the overhead of this.
1575 *
1576 * Return: %true if @p was woken up, %false if it was already running.
1577 * or @state didn't match @p's state.
1578 */
1579static int
1580try_to_wake_up(struct task_struct *p, unsigned int state, int wake_flags)
1581{
1582 unsigned long flags;
1583 int cpu, success = 0;
1584
1585 /*
1586 * If we are going to wake up a thread waiting for CONDITION we
1587 * need to ensure that CONDITION=1 done by the caller can not be
1588 * reordered with p->state check below. This pairs with mb() in
1589 * set_current_state() the waiting thread does.
1590 */
1591 smp_mb__before_spinlock();
1592 raw_spin_lock_irqsave(&p->pi_lock, flags);
1593 if (!(p->state & state))
1594 goto out;
1595
1596 success = 1; /* we're going to change ->state */
1597 cpu = task_cpu(p);
1598
1599 if (p->on_rq && ttwu_remote(p, wake_flags))
1600 goto stat;
1601
1602#ifdef CONFIG_SMP
1603 /*
1604 * If the owning (remote) cpu is still in the middle of schedule() with
1605 * this task as prev, wait until its done referencing the task.
1606 */
1607 while (p->on_cpu)
1608 cpu_relax();
1609 /*
1610 * Pairs with the smp_wmb() in finish_lock_switch().
1611 */
1612 smp_rmb();
1613
1614 p->sched_contributes_to_load = !!task_contributes_to_load(p);
1615 p->state = TASK_WAKING;
1616
1617 if (p->sched_class->task_waking)
1618 p->sched_class->task_waking(p);
1619
1620 cpu = select_task_rq(p, p->wake_cpu, SD_BALANCE_WAKE, wake_flags);
1621 if (task_cpu(p) != cpu) {
1622 wake_flags |= WF_MIGRATED;
1623 set_task_cpu(p, cpu);
1624 }
1625#endif /* CONFIG_SMP */
1626
1627 ttwu_queue(p, cpu);
1628stat:
1629 ttwu_stat(p, cpu, wake_flags);
1630out:
1631 raw_spin_unlock_irqrestore(&p->pi_lock, flags);
1632
1633 return success;
1634}
1635
1636/**
1637 * try_to_wake_up_local - try to wake up a local task with rq lock held
1638 * @p: the thread to be awakened
1639 *
1640 * Put @p on the run-queue if it's not already there. The caller must
1641 * ensure that this_rq() is locked, @p is bound to this_rq() and not
1642 * the current task.
1643 */
1644static void try_to_wake_up_local(struct task_struct *p)
1645{
1646 struct rq *rq = task_rq(p);
1647
1648 if (WARN_ON_ONCE(rq != this_rq()) ||
1649 WARN_ON_ONCE(p == current))
1650 return;
1651
1652 lockdep_assert_held(&rq->lock);
1653
1654 if (!raw_spin_trylock(&p->pi_lock)) {
1655 raw_spin_unlock(&rq->lock);
1656 raw_spin_lock(&p->pi_lock);
1657 raw_spin_lock(&rq->lock);
1658 }
1659
1660 if (!(p->state & TASK_NORMAL))
1661 goto out;
1662
1663 if (!p->on_rq)
1664 ttwu_activate(rq, p, ENQUEUE_WAKEUP);
1665
1666 ttwu_do_wakeup(rq, p, 0);
1667 ttwu_stat(p, smp_processor_id(), 0);
1668out:
1669 raw_spin_unlock(&p->pi_lock);
1670}
1671
1672/**
1673 * wake_up_process - Wake up a specific process
1674 * @p: The process to be woken up.
1675 *
1676 * Attempt to wake up the nominated process and move it to the set of runnable
1677 * processes.
1678 *
1679 * Return: 1 if the process was woken up, 0 if it was already running.
1680 *
1681 * It may be assumed that this function implies a write memory barrier before
1682 * changing the task state if and only if any tasks are woken up.
1683 */
1684int wake_up_process(struct task_struct *p)
1685{
1686 WARN_ON(task_is_stopped_or_traced(p));
1687 return try_to_wake_up(p, TASK_NORMAL, 0);
1688}
1689EXPORT_SYMBOL(wake_up_process);
1690
1691int wake_up_state(struct task_struct *p, unsigned int state)
1692{
1693 return try_to_wake_up(p, state, 0);
1694}
1695
1696/*
1697 * Perform scheduler related setup for a newly forked process p.
1698 * p is forked by current.
1699 *
1700 * __sched_fork() is basic setup used by init_idle() too:
1701 */
1702static void __sched_fork(unsigned long clone_flags, struct task_struct *p)
1703{
1704 p->on_rq = 0;
1705
1706 p->se.on_rq = 0;
1707 p->se.exec_start = 0;
1708 p->se.sum_exec_runtime = 0;
1709 p->se.prev_sum_exec_runtime = 0;
1710 p->se.nr_migrations = 0;
1711 p->se.vruntime = 0;
1712 INIT_LIST_HEAD(&p->se.group_node);
1713
1714#ifdef CONFIG_SCHEDSTATS
1715 memset(&p->se.statistics, 0, sizeof(p->se.statistics));
1716#endif
1717
1718 RB_CLEAR_NODE(&p->dl.rb_node);
1719 hrtimer_init(&p->dl.dl_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
1720 p->dl.dl_runtime = p->dl.runtime = 0;
1721 p->dl.dl_deadline = p->dl.deadline = 0;
1722 p->dl.dl_period = 0;
1723 p->dl.flags = 0;
1724
1725 INIT_LIST_HEAD(&p->rt.run_list);
1726
1727#ifdef CONFIG_PREEMPT_NOTIFIERS
1728 INIT_HLIST_HEAD(&p->preempt_notifiers);
1729#endif
1730
1731#ifdef CONFIG_NUMA_BALANCING
1732 if (p->mm && atomic_read(&p->mm->mm_users) == 1) {
1733 p->mm->numa_next_scan = jiffies + msecs_to_jiffies(sysctl_numa_balancing_scan_delay);
1734 p->mm->numa_scan_seq = 0;
1735 }
1736
1737 if (clone_flags & CLONE_VM)
1738 p->numa_preferred_nid = current->numa_preferred_nid;
1739 else
1740 p->numa_preferred_nid = -1;
1741
1742 p->node_stamp = 0ULL;
1743 p->numa_scan_seq = p->mm ? p->mm->numa_scan_seq : 0;
1744 p->numa_scan_period = sysctl_numa_balancing_scan_delay;
1745 p->numa_work.next = &p->numa_work;
1746 p->numa_faults_memory = NULL;
1747 p->numa_faults_buffer_memory = NULL;
1748 p->last_task_numa_placement = 0;
1749 p->last_sum_exec_runtime = 0;
1750
1751 INIT_LIST_HEAD(&p->numa_entry);
1752 p->numa_group = NULL;
1753#endif /* CONFIG_NUMA_BALANCING */
1754}
1755
1756#ifdef CONFIG_NUMA_BALANCING
1757#ifdef CONFIG_SCHED_DEBUG
1758void set_numabalancing_state(bool enabled)
1759{
1760 if (enabled)
1761 sched_feat_set("NUMA");
1762 else
1763 sched_feat_set("NO_NUMA");
1764}
1765#else
1766__read_mostly bool numabalancing_enabled;
1767
1768void set_numabalancing_state(bool enabled)
1769{
1770 numabalancing_enabled = enabled;
1771}
1772#endif /* CONFIG_SCHED_DEBUG */
1773
1774#ifdef CONFIG_PROC_SYSCTL
1775int sysctl_numa_balancing(struct ctl_table *table, int write,
1776 void __user *buffer, size_t *lenp, loff_t *ppos)
1777{
1778 struct ctl_table t;
1779 int err;
1780 int state = numabalancing_enabled;
1781
1782 if (write && !capable(CAP_SYS_ADMIN))
1783 return -EPERM;
1784
1785 t = *table;
1786 t.data = &state;
1787 err = proc_dointvec_minmax(&t, write, buffer, lenp, ppos);
1788 if (err < 0)
1789 return err;
1790 if (write)
1791 set_numabalancing_state(state);
1792 return err;
1793}
1794#endif
1795#endif
1796
1797/*
1798 * fork()/clone()-time setup:
1799 */
1800int sched_fork(unsigned long clone_flags, struct task_struct *p)
1801{
1802 unsigned long flags;
1803 int cpu = get_cpu();
1804
1805 __sched_fork(clone_flags, p);
1806 /*
1807 * We mark the process as running here. This guarantees that
1808 * nobody will actually run it, and a signal or other external
1809 * event cannot wake it up and insert it on the runqueue either.
1810 */
1811 p->state = TASK_RUNNING;
1812
1813 /*
1814 * Make sure we do not leak PI boosting priority to the child.
1815 */
1816 p->prio = current->normal_prio;
1817
1818 /*
1819 * Revert to default priority/policy on fork if requested.
1820 */
1821 if (unlikely(p->sched_reset_on_fork)) {
1822 if (task_has_dl_policy(p) || task_has_rt_policy(p)) {
1823 p->policy = SCHED_NORMAL;
1824 p->static_prio = NICE_TO_PRIO(0);
1825 p->rt_priority = 0;
1826 } else if (PRIO_TO_NICE(p->static_prio) < 0)
1827 p->static_prio = NICE_TO_PRIO(0);
1828
1829 p->prio = p->normal_prio = __normal_prio(p);
1830 set_load_weight(p);
1831
1832 /*
1833 * We don't need the reset flag anymore after the fork. It has
1834 * fulfilled its duty:
1835 */
1836 p->sched_reset_on_fork = 0;
1837 }
1838
1839 if (dl_prio(p->prio)) {
1840 put_cpu();
1841 return -EAGAIN;
1842 } else if (rt_prio(p->prio)) {
1843 p->sched_class = &rt_sched_class;
1844 } else {
1845 p->sched_class = &fair_sched_class;
1846 }
1847
1848 if (p->sched_class->task_fork)
1849 p->sched_class->task_fork(p);
1850
1851 /*
1852 * The child is not yet in the pid-hash so no cgroup attach races,
1853 * and the cgroup is pinned to this child due to cgroup_fork()
1854 * is ran before sched_fork().
1855 *
1856 * Silence PROVE_RCU.
1857 */
1858 raw_spin_lock_irqsave(&p->pi_lock, flags);
1859 set_task_cpu(p, cpu);
1860 raw_spin_unlock_irqrestore(&p->pi_lock, flags);
1861
1862#if defined(CONFIG_SCHEDSTATS) || defined(CONFIG_TASK_DELAY_ACCT)
1863 if (likely(sched_info_on()))
1864 memset(&p->sched_info, 0, sizeof(p->sched_info));
1865#endif
1866#if defined(CONFIG_SMP)
1867 p->on_cpu = 0;
1868#endif
1869 init_task_preempt_count(p);
1870#ifdef CONFIG_SMP
1871 plist_node_init(&p->pushable_tasks, MAX_PRIO);
1872 RB_CLEAR_NODE(&p->pushable_dl_tasks);
1873#endif
1874
1875 put_cpu();
1876 return 0;
1877}
1878
1879unsigned long to_ratio(u64 period, u64 runtime)
1880{
1881 if (runtime == RUNTIME_INF)
1882 return 1ULL << 20;
1883
1884 /*
1885 * Doing this here saves a lot of checks in all
1886 * the calling paths, and returning zero seems
1887 * safe for them anyway.
1888 */
1889 if (period == 0)
1890 return 0;
1891
1892 return div64_u64(runtime << 20, period);
1893}
1894
1895#ifdef CONFIG_SMP
1896inline struct dl_bw *dl_bw_of(int i)
1897{
1898 return &cpu_rq(i)->rd->dl_bw;
1899}
1900
1901static inline int dl_bw_cpus(int i)
1902{
1903 struct root_domain *rd = cpu_rq(i)->rd;
1904 int cpus = 0;
1905
1906 for_each_cpu_and(i, rd->span, cpu_active_mask)
1907 cpus++;
1908
1909 return cpus;
1910}
1911#else
1912inline struct dl_bw *dl_bw_of(int i)
1913{
1914 return &cpu_rq(i)->dl.dl_bw;
1915}
1916
1917static inline int dl_bw_cpus(int i)
1918{
1919 return 1;
1920}
1921#endif
1922
1923static inline
1924void __dl_clear(struct dl_bw *dl_b, u64 tsk_bw)
1925{
1926 dl_b->total_bw -= tsk_bw;
1927}
1928
1929static inline
1930void __dl_add(struct dl_bw *dl_b, u64 tsk_bw)
1931{
1932 dl_b->total_bw += tsk_bw;
1933}
1934
1935static inline
1936bool __dl_overflow(struct dl_bw *dl_b, int cpus, u64 old_bw, u64 new_bw)
1937{
1938 return dl_b->bw != -1 &&
1939 dl_b->bw * cpus < dl_b->total_bw - old_bw + new_bw;
1940}
1941
1942/*
1943 * We must be sure that accepting a new task (or allowing changing the
1944 * parameters of an existing one) is consistent with the bandwidth
1945 * constraints. If yes, this function also accordingly updates the currently
1946 * allocated bandwidth to reflect the new situation.
1947 *
1948 * This function is called while holding p's rq->lock.
1949 */
1950static int dl_overflow(struct task_struct *p, int policy,
1951 const struct sched_attr *attr)
1952{
1953
1954 struct dl_bw *dl_b = dl_bw_of(task_cpu(p));
1955 u64 period = attr->sched_period ?: attr->sched_deadline;
1956 u64 runtime = attr->sched_runtime;
1957 u64 new_bw = dl_policy(policy) ? to_ratio(period, runtime) : 0;
1958 int cpus, err = -1;
1959
1960 if (new_bw == p->dl.dl_bw)
1961 return 0;
1962
1963 /*
1964 * Either if a task, enters, leave, or stays -deadline but changes
1965 * its parameters, we may need to update accordingly the total
1966 * allocated bandwidth of the container.
1967 */
1968 raw_spin_lock(&dl_b->lock);
1969 cpus = dl_bw_cpus(task_cpu(p));
1970 if (dl_policy(policy) && !task_has_dl_policy(p) &&
1971 !__dl_overflow(dl_b, cpus, 0, new_bw)) {
1972 __dl_add(dl_b, new_bw);
1973 err = 0;
1974 } else if (dl_policy(policy) && task_has_dl_policy(p) &&
1975 !__dl_overflow(dl_b, cpus, p->dl.dl_bw, new_bw)) {
1976 __dl_clear(dl_b, p->dl.dl_bw);
1977 __dl_add(dl_b, new_bw);
1978 err = 0;
1979 } else if (!dl_policy(policy) && task_has_dl_policy(p)) {
1980 __dl_clear(dl_b, p->dl.dl_bw);
1981 err = 0;
1982 }
1983 raw_spin_unlock(&dl_b->lock);
1984
1985 return err;
1986}
1987
1988extern void init_dl_bw(struct dl_bw *dl_b);
1989
1990/*
1991 * wake_up_new_task - wake up a newly created task for the first time.
1992 *
1993 * This function will do some initial scheduler statistics housekeeping
1994 * that must be done for every newly created context, then puts the task
1995 * on the runqueue and wakes it.
1996 */
1997void wake_up_new_task(struct task_struct *p)
1998{
1999 unsigned long flags;
2000 struct rq *rq;
2001
2002 raw_spin_lock_irqsave(&p->pi_lock, flags);
2003#ifdef CONFIG_SMP
2004 /*
2005 * Fork balancing, do it here and not earlier because:
2006 * - cpus_allowed can change in the fork path
2007 * - any previously selected cpu might disappear through hotplug
2008 */
2009 set_task_cpu(p, select_task_rq(p, task_cpu(p), SD_BALANCE_FORK, 0));
2010#endif
2011
2012 /* Initialize new task's runnable average */
2013 init_task_runnable_average(p);
2014 rq = __task_rq_lock(p);
2015 activate_task(rq, p, 0);
2016 p->on_rq = 1;
2017 trace_sched_wakeup_new(p, true);
2018 check_preempt_curr(rq, p, WF_FORK);
2019#ifdef CONFIG_SMP
2020 if (p->sched_class->task_woken)
2021 p->sched_class->task_woken(rq, p);
2022#endif
2023 task_rq_unlock(rq, p, &flags);
2024}
2025
2026#ifdef CONFIG_PREEMPT_NOTIFIERS
2027
2028/**
2029 * preempt_notifier_register - tell me when current is being preempted & rescheduled
2030 * @notifier: notifier struct to register
2031 */
2032void preempt_notifier_register(struct preempt_notifier *notifier)
2033{
2034 hlist_add_head(¬ifier->link, ¤t->preempt_notifiers);
2035}
2036EXPORT_SYMBOL_GPL(preempt_notifier_register);
2037
2038/**
2039 * preempt_notifier_unregister - no longer interested in preemption notifications
2040 * @notifier: notifier struct to unregister
2041 *
2042 * This is safe to call from within a preemption notifier.
2043 */
2044void preempt_notifier_unregister(struct preempt_notifier *notifier)
2045{
2046 hlist_del(¬ifier->link);
2047}
2048EXPORT_SYMBOL_GPL(preempt_notifier_unregister);
2049
2050static void fire_sched_in_preempt_notifiers(struct task_struct *curr)
2051{
2052 struct preempt_notifier *notifier;
2053
2054 hlist_for_each_entry(notifier, &curr->preempt_notifiers, link)
2055 notifier->ops->sched_in(notifier, raw_smp_processor_id());
2056}
2057
2058static void
2059fire_sched_out_preempt_notifiers(struct task_struct *curr,
2060 struct task_struct *next)
2061{
2062 struct preempt_notifier *notifier;
2063
2064 hlist_for_each_entry(notifier, &curr->preempt_notifiers, link)
2065 notifier->ops->sched_out(notifier, next);
2066}
2067
2068#else /* !CONFIG_PREEMPT_NOTIFIERS */
2069
2070static void fire_sched_in_preempt_notifiers(struct task_struct *curr)
2071{
2072}
2073
2074static void
2075fire_sched_out_preempt_notifiers(struct task_struct *curr,
2076 struct task_struct *next)
2077{
2078}
2079
2080#endif /* CONFIG_PREEMPT_NOTIFIERS */
2081
2082/**
2083 * prepare_task_switch - prepare to switch tasks
2084 * @rq: the runqueue preparing to switch
2085 * @prev: the current task that is being switched out
2086 * @next: the task we are going to switch to.
2087 *
2088 * This is called with the rq lock held and interrupts off. It must
2089 * be paired with a subsequent finish_task_switch after the context
2090 * switch.
2091 *
2092 * prepare_task_switch sets up locking and calls architecture specific
2093 * hooks.
2094 */
2095static inline void
2096prepare_task_switch(struct rq *rq, struct task_struct *prev,
2097 struct task_struct *next)
2098{
2099 trace_sched_switch(prev, next);
2100 sched_info_switch(rq, prev, next);
2101 perf_event_task_sched_out(prev, next);
2102 fire_sched_out_preempt_notifiers(prev, next);
2103 prepare_lock_switch(rq, next);
2104 prepare_arch_switch(next);
2105}
2106
2107/**
2108 * finish_task_switch - clean up after a task-switch
2109 * @rq: runqueue associated with task-switch
2110 * @prev: the thread we just switched away from.
2111 *
2112 * finish_task_switch must be called after the context switch, paired
2113 * with a prepare_task_switch call before the context switch.
2114 * finish_task_switch will reconcile locking set up by prepare_task_switch,
2115 * and do any other architecture-specific cleanup actions.
2116 *
2117 * Note that we may have delayed dropping an mm in context_switch(). If
2118 * so, we finish that here outside of the runqueue lock. (Doing it
2119 * with the lock held can cause deadlocks; see schedule() for
2120 * details.)
2121 */
2122static void finish_task_switch(struct rq *rq, struct task_struct *prev)
2123 __releases(rq->lock)
2124{
2125 struct mm_struct *mm = rq->prev_mm;
2126 long prev_state;
2127
2128 rq->prev_mm = NULL;
2129
2130 /*
2131 * A task struct has one reference for the use as "current".
2132 * If a task dies, then it sets TASK_DEAD in tsk->state and calls
2133 * schedule one last time. The schedule call will never return, and
2134 * the scheduled task must drop that reference.
2135 * The test for TASK_DEAD must occur while the runqueue locks are
2136 * still held, otherwise prev could be scheduled on another cpu, die
2137 * there before we look at prev->state, and then the reference would
2138 * be dropped twice.
2139 * Manfred Spraul <manfred@colorfullife.com>
2140 */
2141 prev_state = prev->state;
2142 vtime_task_switch(prev);
2143 finish_arch_switch(prev);
2144 perf_event_task_sched_in(prev, current);
2145 finish_lock_switch(rq, prev);
2146 finish_arch_post_lock_switch();
2147
2148 fire_sched_in_preempt_notifiers(current);
2149 if (mm)
2150 mmdrop(mm);
2151 if (unlikely(prev_state == TASK_DEAD)) {
2152 if (prev->sched_class->task_dead)
2153 prev->sched_class->task_dead(prev);
2154
2155 /*
2156 * Remove function-return probe instances associated with this
2157 * task and put them back on the free list.
2158 */
2159 kprobe_flush_task(prev);
2160 put_task_struct(prev);
2161 }
2162
2163 tick_nohz_task_switch(current);
2164}
2165
2166#ifdef CONFIG_SMP
2167
2168/* rq->lock is NOT held, but preemption is disabled */
2169static inline void post_schedule(struct rq *rq)
2170{
2171 if (rq->post_schedule) {
2172 unsigned long flags;
2173
2174 raw_spin_lock_irqsave(&rq->lock, flags);
2175 if (rq->curr->sched_class->post_schedule)
2176 rq->curr->sched_class->post_schedule(rq);
2177 raw_spin_unlock_irqrestore(&rq->lock, flags);
2178
2179 rq->post_schedule = 0;
2180 }
2181}
2182
2183#else
2184
2185static inline void post_schedule(struct rq *rq)
2186{
2187}
2188
2189#endif
2190
2191/**
2192 * schedule_tail - first thing a freshly forked thread must call.
2193 * @prev: the thread we just switched away from.
2194 */
2195asmlinkage __visible void schedule_tail(struct task_struct *prev)
2196 __releases(rq->lock)
2197{
2198 struct rq *rq = this_rq();
2199
2200 finish_task_switch(rq, prev);
2201
2202 /*
2203 * FIXME: do we need to worry about rq being invalidated by the
2204 * task_switch?
2205 */
2206 post_schedule(rq);
2207
2208#ifdef __ARCH_WANT_UNLOCKED_CTXSW
2209 /* In this case, finish_task_switch does not reenable preemption */
2210 preempt_enable();
2211#endif
2212 if (current->set_child_tid)
2213 put_user(task_pid_vnr(current), current->set_child_tid);
2214}
2215
2216/*
2217 * context_switch - switch to the new MM and the new
2218 * thread's register state.
2219 */
2220static inline void
2221context_switch(struct rq *rq, struct task_struct *prev,
2222 struct task_struct *next)
2223{
2224 struct mm_struct *mm, *oldmm;
2225
2226 prepare_task_switch(rq, prev, next);
2227
2228 mm = next->mm;
2229 oldmm = prev->active_mm;
2230 /*
2231 * For paravirt, this is coupled with an exit in switch_to to
2232 * combine the page table reload and the switch backend into
2233 * one hypercall.
2234 */
2235 arch_start_context_switch(prev);
2236
2237 if (!mm) {
2238 next->active_mm = oldmm;
2239 atomic_inc(&oldmm->mm_count);
2240 enter_lazy_tlb(oldmm, next);
2241 } else
2242 switch_mm(oldmm, mm, next);
2243
2244 if (!prev->mm) {
2245 prev->active_mm = NULL;
2246 rq->prev_mm = oldmm;
2247 }
2248 /*
2249 * Since the runqueue lock will be released by the next
2250 * task (which is an invalid locking op but in the case
2251 * of the scheduler it's an obvious special-case), so we
2252 * do an early lockdep release here:
2253 */
2254#ifndef __ARCH_WANT_UNLOCKED_CTXSW
2255 spin_release(&rq->lock.dep_map, 1, _THIS_IP_);
2256#endif
2257
2258 context_tracking_task_switch(prev, next);
2259 /* Here we just switch the register state and the stack. */
2260 switch_to(prev, next, prev);
2261
2262 barrier();
2263 /*
2264 * this_rq must be evaluated again because prev may have moved
2265 * CPUs since it called schedule(), thus the 'rq' on its stack
2266 * frame will be invalid.
2267 */
2268 finish_task_switch(this_rq(), prev);
2269}
2270
2271/*
2272 * nr_running and nr_context_switches:
2273 *
2274 * externally visible scheduler statistics: current number of runnable
2275 * threads, total number of context switches performed since bootup.
2276 */
2277unsigned long nr_running(void)
2278{
2279 unsigned long i, sum = 0;
2280
2281 for_each_online_cpu(i)
2282 sum += cpu_rq(i)->nr_running;
2283
2284 return sum;
2285}
2286
2287unsigned long long nr_context_switches(void)
2288{
2289 int i;
2290 unsigned long long sum = 0;
2291
2292 for_each_possible_cpu(i)
2293 sum += cpu_rq(i)->nr_switches;
2294
2295 return sum;
2296}
2297
2298unsigned long nr_iowait(void)
2299{
2300 unsigned long i, sum = 0;
2301
2302 for_each_possible_cpu(i)
2303 sum += atomic_read(&cpu_rq(i)->nr_iowait);
2304
2305 return sum;
2306}
2307
2308unsigned long nr_iowait_cpu(int cpu)
2309{
2310 struct rq *this = cpu_rq(cpu);
2311 return atomic_read(&this->nr_iowait);
2312}
2313
2314#ifdef CONFIG_SMP
2315
2316/*
2317 * sched_exec - execve() is a valuable balancing opportunity, because at
2318 * this point the task has the smallest effective memory and cache footprint.
2319 */
2320void sched_exec(void)
2321{
2322 struct task_struct *p = current;
2323 unsigned long flags;
2324 int dest_cpu;
2325
2326 raw_spin_lock_irqsave(&p->pi_lock, flags);
2327 dest_cpu = p->sched_class->select_task_rq(p, task_cpu(p), SD_BALANCE_EXEC, 0);
2328 if (dest_cpu == smp_processor_id())
2329 goto unlock;
2330
2331 if (likely(cpu_active(dest_cpu))) {
2332 struct migration_arg arg = { p, dest_cpu };
2333
2334 raw_spin_unlock_irqrestore(&p->pi_lock, flags);
2335 stop_one_cpu(task_cpu(p), migration_cpu_stop, &arg);
2336 return;
2337 }
2338unlock:
2339 raw_spin_unlock_irqrestore(&p->pi_lock, flags);
2340}
2341
2342#endif
2343
2344DEFINE_PER_CPU(struct kernel_stat, kstat);
2345DEFINE_PER_CPU(struct kernel_cpustat, kernel_cpustat);
2346
2347EXPORT_PER_CPU_SYMBOL(kstat);
2348EXPORT_PER_CPU_SYMBOL(kernel_cpustat);
2349
2350/*
2351 * Return any ns on the sched_clock that have not yet been accounted in
2352 * @p in case that task is currently running.
2353 *
2354 * Called with task_rq_lock() held on @rq.
2355 */
2356static u64 do_task_delta_exec(struct task_struct *p, struct rq *rq)
2357{
2358 u64 ns = 0;
2359
2360 if (task_current(rq, p)) {
2361 update_rq_clock(rq);
2362 ns = rq_clock_task(rq) - p->se.exec_start;
2363 if ((s64)ns < 0)
2364 ns = 0;
2365 }
2366
2367 return ns;
2368}
2369
2370unsigned long long task_delta_exec(struct task_struct *p)
2371{
2372 unsigned long flags;
2373 struct rq *rq;
2374 u64 ns = 0;
2375
2376 rq = task_rq_lock(p, &flags);
2377 ns = do_task_delta_exec(p, rq);
2378 task_rq_unlock(rq, p, &flags);
2379
2380 return ns;
2381}
2382
2383/*
2384 * Return accounted runtime for the task.
2385 * In case the task is currently running, return the runtime plus current's
2386 * pending runtime that have not been accounted yet.
2387 */
2388unsigned long long task_sched_runtime(struct task_struct *p)
2389{
2390 unsigned long flags;
2391 struct rq *rq;
2392 u64 ns = 0;
2393
2394#if defined(CONFIG_64BIT) && defined(CONFIG_SMP)
2395 /*
2396 * 64-bit doesn't need locks to atomically read a 64bit value.
2397 * So we have a optimization chance when the task's delta_exec is 0.
2398 * Reading ->on_cpu is racy, but this is ok.
2399 *
2400 * If we race with it leaving cpu, we'll take a lock. So we're correct.
2401 * If we race with it entering cpu, unaccounted time is 0. This is
2402 * indistinguishable from the read occurring a few cycles earlier.
2403 */
2404 if (!p->on_cpu)
2405 return p->se.sum_exec_runtime;
2406#endif
2407
2408 rq = task_rq_lock(p, &flags);
2409 ns = p->se.sum_exec_runtime + do_task_delta_exec(p, rq);
2410 task_rq_unlock(rq, p, &flags);
2411
2412 return ns;
2413}
2414
2415/*
2416 * This function gets called by the timer code, with HZ frequency.
2417 * We call it with interrupts disabled.
2418 */
2419void scheduler_tick(void)
2420{
2421 int cpu = smp_processor_id();
2422 struct rq *rq = cpu_rq(cpu);
2423 struct task_struct *curr = rq->curr;
2424
2425 sched_clock_tick();
2426
2427 raw_spin_lock(&rq->lock);
2428 update_rq_clock(rq);
2429 curr->sched_class->task_tick(rq, curr, 0);
2430 update_cpu_load_active(rq);
2431 raw_spin_unlock(&rq->lock);
2432
2433 perf_event_task_tick();
2434
2435#ifdef CONFIG_SMP
2436 rq->idle_balance = idle_cpu(cpu);
2437 trigger_load_balance(rq);
2438#endif
2439 rq_last_tick_reset(rq);
2440}
2441
2442#ifdef CONFIG_NO_HZ_FULL
2443/**
2444 * scheduler_tick_max_deferment
2445 *
2446 * Keep at least one tick per second when a single
2447 * active task is running because the scheduler doesn't
2448 * yet completely support full dynticks environment.
2449 *
2450 * This makes sure that uptime, CFS vruntime, load
2451 * balancing, etc... continue to move forward, even
2452 * with a very low granularity.
2453 *
2454 * Return: Maximum deferment in nanoseconds.
2455 */
2456u64 scheduler_tick_max_deferment(void)
2457{
2458 struct rq *rq = this_rq();
2459 unsigned long next, now = ACCESS_ONCE(jiffies);
2460
2461 next = rq->last_sched_tick + HZ;
2462
2463 if (time_before_eq(next, now))
2464 return 0;
2465
2466 return jiffies_to_nsecs(next - now);
2467}
2468#endif
2469
2470notrace unsigned long get_parent_ip(unsigned long addr)
2471{
2472 if (in_lock_functions(addr)) {
2473 addr = CALLER_ADDR2;
2474 if (in_lock_functions(addr))
2475 addr = CALLER_ADDR3;
2476 }
2477 return addr;
2478}
2479
2480#if defined(CONFIG_PREEMPT) && (defined(CONFIG_DEBUG_PREEMPT) || \
2481 defined(CONFIG_PREEMPT_TRACER))
2482
2483void __kprobes preempt_count_add(int val)
2484{
2485#ifdef CONFIG_DEBUG_PREEMPT
2486 /*
2487 * Underflow?
2488 */
2489 if (DEBUG_LOCKS_WARN_ON((preempt_count() < 0)))
2490 return;
2491#endif
2492 __preempt_count_add(val);
2493#ifdef CONFIG_DEBUG_PREEMPT
2494 /*
2495 * Spinlock count overflowing soon?
2496 */
2497 DEBUG_LOCKS_WARN_ON((preempt_count() & PREEMPT_MASK) >=
2498 PREEMPT_MASK - 10);
2499#endif
2500 if (preempt_count() == val) {
2501 unsigned long ip = get_parent_ip(CALLER_ADDR1);
2502#ifdef CONFIG_DEBUG_PREEMPT
2503 current->preempt_disable_ip = ip;
2504#endif
2505 trace_preempt_off(CALLER_ADDR0, ip);
2506 }
2507}
2508EXPORT_SYMBOL(preempt_count_add);
2509
2510void __kprobes preempt_count_sub(int val)
2511{
2512#ifdef CONFIG_DEBUG_PREEMPT
2513 /*
2514 * Underflow?
2515 */
2516 if (DEBUG_LOCKS_WARN_ON(val > preempt_count()))
2517 return;
2518 /*
2519 * Is the spinlock portion underflowing?
2520 */
2521 if (DEBUG_LOCKS_WARN_ON((val < PREEMPT_MASK) &&
2522 !(preempt_count() & PREEMPT_MASK)))
2523 return;
2524#endif
2525
2526 if (preempt_count() == val)
2527 trace_preempt_on(CALLER_ADDR0, get_parent_ip(CALLER_ADDR1));
2528 __preempt_count_sub(val);
2529}
2530EXPORT_SYMBOL(preempt_count_sub);
2531
2532#endif
2533
2534/*
2535 * Print scheduling while atomic bug:
2536 */
2537static noinline void __schedule_bug(struct task_struct *prev)
2538{
2539 if (oops_in_progress)
2540 return;
2541
2542 printk(KERN_ERR "BUG: scheduling while atomic: %s/%d/0x%08x\n",
2543 prev->comm, prev->pid, preempt_count());
2544
2545 debug_show_held_locks(prev);
2546 print_modules();
2547 if (irqs_disabled())
2548 print_irqtrace_events(prev);
2549#ifdef CONFIG_DEBUG_PREEMPT
2550 if (in_atomic_preempt_off()) {
2551 pr_err("Preemption disabled at:");
2552 print_ip_sym(current->preempt_disable_ip);
2553 pr_cont("\n");
2554 }
2555#endif
2556 dump_stack();
2557 add_taint(TAINT_WARN, LOCKDEP_STILL_OK);
2558}
2559
2560/*
2561 * Various schedule()-time debugging checks and statistics:
2562 */
2563static inline void schedule_debug(struct task_struct *prev)
2564{
2565 /*
2566 * Test if we are atomic. Since do_exit() needs to call into
2567 * schedule() atomically, we ignore that path. Otherwise whine
2568 * if we are scheduling when we should not.
2569 */
2570 if (unlikely(in_atomic_preempt_off() && prev->state != TASK_DEAD))
2571 __schedule_bug(prev);
2572 rcu_sleep_check();
2573
2574 profile_hit(SCHED_PROFILING, __builtin_return_address(0));
2575
2576 schedstat_inc(this_rq(), sched_count);
2577}
2578
2579/*
2580 * Pick up the highest-prio task:
2581 */
2582static inline struct task_struct *
2583pick_next_task(struct rq *rq, struct task_struct *prev)
2584{
2585 const struct sched_class *class = &fair_sched_class;
2586 struct task_struct *p;
2587
2588 /*
2589 * Optimization: we know that if all tasks are in
2590 * the fair class we can call that function directly:
2591 */
2592 if (likely(prev->sched_class == class &&
2593 rq->nr_running == rq->cfs.h_nr_running)) {
2594 p = fair_sched_class.pick_next_task(rq, prev);
2595 if (unlikely(p == RETRY_TASK))
2596 goto again;
2597
2598 /* assumes fair_sched_class->next == idle_sched_class */
2599 if (unlikely(!p))
2600 p = idle_sched_class.pick_next_task(rq, prev);
2601
2602 return p;
2603 }
2604
2605again:
2606 for_each_class(class) {
2607 p = class->pick_next_task(rq, prev);
2608 if (p) {
2609 if (unlikely(p == RETRY_TASK))
2610 goto again;
2611 return p;
2612 }
2613 }
2614
2615 BUG(); /* the idle class will always have a runnable task */
2616}
2617
2618/*
2619 * __schedule() is the main scheduler function.
2620 *
2621 * The main means of driving the scheduler and thus entering this function are:
2622 *
2623 * 1. Explicit blocking: mutex, semaphore, waitqueue, etc.
2624 *
2625 * 2. TIF_NEED_RESCHED flag is checked on interrupt and userspace return
2626 * paths. For example, see arch/x86/entry_64.S.
2627 *
2628 * To drive preemption between tasks, the scheduler sets the flag in timer
2629 * interrupt handler scheduler_tick().
2630 *
2631 * 3. Wakeups don't really cause entry into schedule(). They add a
2632 * task to the run-queue and that's it.
2633 *
2634 * Now, if the new task added to the run-queue preempts the current
2635 * task, then the wakeup sets TIF_NEED_RESCHED and schedule() gets
2636 * called on the nearest possible occasion:
2637 *
2638 * - If the kernel is preemptible (CONFIG_PREEMPT=y):
2639 *
2640 * - in syscall or exception context, at the next outmost
2641 * preempt_enable(). (this might be as soon as the wake_up()'s
2642 * spin_unlock()!)
2643 *
2644 * - in IRQ context, return from interrupt-handler to
2645 * preemptible context
2646 *
2647 * - If the kernel is not preemptible (CONFIG_PREEMPT is not set)
2648 * then at the next:
2649 *
2650 * - cond_resched() call
2651 * - explicit schedule() call
2652 * - return from syscall or exception to user-space
2653 * - return from interrupt-handler to user-space
2654 */
2655static void __sched __schedule(void)
2656{
2657 struct task_struct *prev, *next;
2658 unsigned long *switch_count;
2659 struct rq *rq;
2660 int cpu;
2661
2662need_resched:
2663 preempt_disable();
2664 cpu = smp_processor_id();
2665 rq = cpu_rq(cpu);
2666 rcu_note_context_switch(cpu);
2667 prev = rq->curr;
2668
2669 schedule_debug(prev);
2670
2671 if (sched_feat(HRTICK))
2672 hrtick_clear(rq);
2673
2674 /*
2675 * Make sure that signal_pending_state()->signal_pending() below
2676 * can't be reordered with __set_current_state(TASK_INTERRUPTIBLE)
2677 * done by the caller to avoid the race with signal_wake_up().
2678 */
2679 smp_mb__before_spinlock();
2680 raw_spin_lock_irq(&rq->lock);
2681
2682 switch_count = &prev->nivcsw;
2683 if (prev->state && !(preempt_count() & PREEMPT_ACTIVE)) {
2684 if (unlikely(signal_pending_state(prev->state, prev))) {
2685 prev->state = TASK_RUNNING;
2686 } else {
2687 deactivate_task(rq, prev, DEQUEUE_SLEEP);
2688 prev->on_rq = 0;
2689
2690 /*
2691 * If a worker went to sleep, notify and ask workqueue
2692 * whether it wants to wake up a task to maintain
2693 * concurrency.
2694 */
2695 if (prev->flags & PF_WQ_WORKER) {
2696 struct task_struct *to_wakeup;
2697
2698 to_wakeup = wq_worker_sleeping(prev, cpu);
2699 if (to_wakeup)
2700 try_to_wake_up_local(to_wakeup);
2701 }
2702 }
2703 switch_count = &prev->nvcsw;
2704 }
2705
2706 if (prev->on_rq || rq->skip_clock_update < 0)
2707 update_rq_clock(rq);
2708
2709 next = pick_next_task(rq, prev);
2710 clear_tsk_need_resched(prev);
2711 clear_preempt_need_resched();
2712 rq->skip_clock_update = 0;
2713
2714 if (likely(prev != next)) {
2715 rq->nr_switches++;
2716 rq->curr = next;
2717 ++*switch_count;
2718
2719 context_switch(rq, prev, next); /* unlocks the rq */
2720 /*
2721 * The context switch have flipped the stack from under us
2722 * and restored the local variables which were saved when
2723 * this task called schedule() in the past. prev == current
2724 * is still correct, but it can be moved to another cpu/rq.
2725 */
2726 cpu = smp_processor_id();
2727 rq = cpu_rq(cpu);
2728 } else
2729 raw_spin_unlock_irq(&rq->lock);
2730
2731 post_schedule(rq);
2732
2733 sched_preempt_enable_no_resched();
2734 if (need_resched())
2735 goto need_resched;
2736}
2737
2738static inline void sched_submit_work(struct task_struct *tsk)
2739{
2740 if (!tsk->state || tsk_is_pi_blocked(tsk))
2741 return;
2742 /*
2743 * If we are going to sleep and we have plugged IO queued,
2744 * make sure to submit it to avoid deadlocks.
2745 */
2746 if (blk_needs_flush_plug(tsk))
2747 blk_schedule_flush_plug(tsk);
2748}
2749
2750asmlinkage __visible void __sched schedule(void)
2751{
2752 struct task_struct *tsk = current;
2753
2754 sched_submit_work(tsk);
2755 __schedule();
2756}
2757EXPORT_SYMBOL(schedule);
2758
2759#ifdef CONFIG_CONTEXT_TRACKING
2760asmlinkage __visible void __sched schedule_user(void)
2761{
2762 /*
2763 * If we come here after a random call to set_need_resched(),
2764 * or we have been woken up remotely but the IPI has not yet arrived,
2765 * we haven't yet exited the RCU idle mode. Do it here manually until
2766 * we find a better solution.
2767 */
2768 user_exit();
2769 schedule();
2770 user_enter();
2771}
2772#endif
2773
2774/**
2775 * schedule_preempt_disabled - called with preemption disabled
2776 *
2777 * Returns with preemption disabled. Note: preempt_count must be 1
2778 */
2779void __sched schedule_preempt_disabled(void)
2780{
2781 sched_preempt_enable_no_resched();
2782 schedule();
2783 preempt_disable();
2784}
2785
2786#ifdef CONFIG_PREEMPT
2787/*
2788 * this is the entry point to schedule() from in-kernel preemption
2789 * off of preempt_enable. Kernel preemptions off return from interrupt
2790 * occur there and call schedule directly.
2791 */
2792asmlinkage __visible void __sched notrace preempt_schedule(void)
2793{
2794 /*
2795 * If there is a non-zero preempt_count or interrupts are disabled,
2796 * we do not want to preempt the current task. Just return..
2797 */
2798 if (likely(!preemptible()))
2799 return;
2800
2801 do {
2802 __preempt_count_add(PREEMPT_ACTIVE);
2803 __schedule();
2804 __preempt_count_sub(PREEMPT_ACTIVE);
2805
2806 /*
2807 * Check again in case we missed a preemption opportunity
2808 * between schedule and now.
2809 */
2810 barrier();
2811 } while (need_resched());
2812}
2813EXPORT_SYMBOL(preempt_schedule);
2814#endif /* CONFIG_PREEMPT */
2815
2816/*
2817 * this is the entry point to schedule() from kernel preemption
2818 * off of irq context.
2819 * Note, that this is called and return with irqs disabled. This will
2820 * protect us against recursive calling from irq.
2821 */
2822asmlinkage __visible void __sched preempt_schedule_irq(void)
2823{
2824 enum ctx_state prev_state;
2825
2826 /* Catch callers which need to be fixed */
2827 BUG_ON(preempt_count() || !irqs_disabled());
2828
2829 prev_state = exception_enter();
2830
2831 do {
2832 __preempt_count_add(PREEMPT_ACTIVE);
2833 local_irq_enable();
2834 __schedule();
2835 local_irq_disable();
2836 __preempt_count_sub(PREEMPT_ACTIVE);
2837
2838 /*
2839 * Check again in case we missed a preemption opportunity
2840 * between schedule and now.
2841 */
2842 barrier();
2843 } while (need_resched());
2844
2845 exception_exit(prev_state);
2846}
2847
2848int default_wake_function(wait_queue_t *curr, unsigned mode, int wake_flags,
2849 void *key)
2850{
2851 return try_to_wake_up(curr->private, mode, wake_flags);
2852}
2853EXPORT_SYMBOL(default_wake_function);
2854
2855#ifdef CONFIG_RT_MUTEXES
2856
2857/*
2858 * rt_mutex_setprio - set the current priority of a task
2859 * @p: task
2860 * @prio: prio value (kernel-internal form)
2861 *
2862 * This function changes the 'effective' priority of a task. It does
2863 * not touch ->normal_prio like __setscheduler().
2864 *
2865 * Used by the rt_mutex code to implement priority inheritance
2866 * logic. Call site only calls if the priority of the task changed.
2867 */
2868void rt_mutex_setprio(struct task_struct *p, int prio)
2869{
2870 int oldprio, on_rq, running, enqueue_flag = 0;
2871 struct rq *rq;
2872 const struct sched_class *prev_class;
2873
2874 BUG_ON(prio > MAX_PRIO);
2875
2876 rq = __task_rq_lock(p);
2877
2878 /*
2879 * Idle task boosting is a nono in general. There is one
2880 * exception, when PREEMPT_RT and NOHZ is active:
2881 *
2882 * The idle task calls get_next_timer_interrupt() and holds
2883 * the timer wheel base->lock on the CPU and another CPU wants
2884 * to access the timer (probably to cancel it). We can safely
2885 * ignore the boosting request, as the idle CPU runs this code
2886 * with interrupts disabled and will complete the lock
2887 * protected section without being interrupted. So there is no
2888 * real need to boost.
2889 */
2890 if (unlikely(p == rq->idle)) {
2891 WARN_ON(p != rq->curr);
2892 WARN_ON(p->pi_blocked_on);
2893 goto out_unlock;
2894 }
2895
2896 trace_sched_pi_setprio(p, prio);
2897 p->pi_top_task = rt_mutex_get_top_task(p);
2898 oldprio = p->prio;
2899 prev_class = p->sched_class;
2900 on_rq = p->on_rq;
2901 running = task_current(rq, p);
2902 if (on_rq)
2903 dequeue_task(rq, p, 0);
2904 if (running)
2905 p->sched_class->put_prev_task(rq, p);
2906
2907 /*
2908 * Boosting condition are:
2909 * 1. -rt task is running and holds mutex A
2910 * --> -dl task blocks on mutex A
2911 *
2912 * 2. -dl task is running and holds mutex A
2913 * --> -dl task blocks on mutex A and could preempt the
2914 * running task
2915 */
2916 if (dl_prio(prio)) {
2917 if (!dl_prio(p->normal_prio) || (p->pi_top_task &&
2918 dl_entity_preempt(&p->pi_top_task->dl, &p->dl))) {
2919 p->dl.dl_boosted = 1;
2920 p->dl.dl_throttled = 0;
2921 enqueue_flag = ENQUEUE_REPLENISH;
2922 } else
2923 p->dl.dl_boosted = 0;
2924 p->sched_class = &dl_sched_class;
2925 } else if (rt_prio(prio)) {
2926 if (dl_prio(oldprio))
2927 p->dl.dl_boosted = 0;
2928 if (oldprio < prio)
2929 enqueue_flag = ENQUEUE_HEAD;
2930 p->sched_class = &rt_sched_class;
2931 } else {
2932 if (dl_prio(oldprio))
2933 p->dl.dl_boosted = 0;
2934 p->sched_class = &fair_sched_class;
2935 }
2936
2937 p->prio = prio;
2938
2939 if (running)
2940 p->sched_class->set_curr_task(rq);
2941 if (on_rq)
2942 enqueue_task(rq, p, enqueue_flag);
2943
2944 check_class_changed(rq, p, prev_class, oldprio);
2945out_unlock:
2946 __task_rq_unlock(rq);
2947}
2948#endif
2949
2950void set_user_nice(struct task_struct *p, long nice)
2951{
2952 int old_prio, delta, on_rq;
2953 unsigned long flags;
2954 struct rq *rq;
2955
2956 if (task_nice(p) == nice || nice < MIN_NICE || nice > MAX_NICE)
2957 return;
2958 /*
2959 * We have to be careful, if called from sys_setpriority(),
2960 * the task might be in the middle of scheduling on another CPU.
2961 */
2962 rq = task_rq_lock(p, &flags);
2963 /*
2964 * The RT priorities are set via sched_setscheduler(), but we still
2965 * allow the 'normal' nice value to be set - but as expected
2966 * it wont have any effect on scheduling until the task is
2967 * SCHED_DEADLINE, SCHED_FIFO or SCHED_RR:
2968 */
2969 if (task_has_dl_policy(p) || task_has_rt_policy(p)) {
2970 p->static_prio = NICE_TO_PRIO(nice);
2971 goto out_unlock;
2972 }
2973 on_rq = p->on_rq;
2974 if (on_rq)
2975 dequeue_task(rq, p, 0);
2976
2977 p->static_prio = NICE_TO_PRIO(nice);
2978 set_load_weight(p);
2979 old_prio = p->prio;
2980 p->prio = effective_prio(p);
2981 delta = p->prio - old_prio;
2982
2983 if (on_rq) {
2984 enqueue_task(rq, p, 0);
2985 /*
2986 * If the task increased its priority or is running and
2987 * lowered its priority, then reschedule its CPU:
2988 */
2989 if (delta < 0 || (delta > 0 && task_running(rq, p)))
2990 resched_task(rq->curr);
2991 }
2992out_unlock:
2993 task_rq_unlock(rq, p, &flags);
2994}
2995EXPORT_SYMBOL(set_user_nice);
2996
2997/*
2998 * can_nice - check if a task can reduce its nice value
2999 * @p: task
3000 * @nice: nice value
3001 */
3002int can_nice(const struct task_struct *p, const int nice)
3003{
3004 /* convert nice value [19,-20] to rlimit style value [1,40] */
3005 int nice_rlim = 20 - nice;
3006
3007 return (nice_rlim <= task_rlimit(p, RLIMIT_NICE) ||
3008 capable(CAP_SYS_NICE));
3009}
3010
3011#ifdef __ARCH_WANT_SYS_NICE
3012
3013/*
3014 * sys_nice - change the priority of the current process.
3015 * @increment: priority increment
3016 *
3017 * sys_setpriority is a more generic, but much slower function that
3018 * does similar things.
3019 */
3020SYSCALL_DEFINE1(nice, int, increment)
3021{
3022 long nice, retval;
3023
3024 /*
3025 * Setpriority might change our priority at the same moment.
3026 * We don't have to worry. Conceptually one call occurs first
3027 * and we have a single winner.
3028 */
3029 if (increment < -40)
3030 increment = -40;
3031 if (increment > 40)
3032 increment = 40;
3033
3034 nice = task_nice(current) + increment;
3035 if (nice < MIN_NICE)
3036 nice = MIN_NICE;
3037 if (nice > MAX_NICE)
3038 nice = MAX_NICE;
3039
3040 if (increment < 0 && !can_nice(current, nice))
3041 return -EPERM;
3042
3043 retval = security_task_setnice(current, nice);
3044 if (retval)
3045 return retval;
3046
3047 set_user_nice(current, nice);
3048 return 0;
3049}
3050
3051#endif
3052
3053/**
3054 * task_prio - return the priority value of a given task.
3055 * @p: the task in question.
3056 *
3057 * Return: The priority value as seen by users in /proc.
3058 * RT tasks are offset by -200. Normal tasks are centered
3059 * around 0, value goes from -16 to +15.
3060 */
3061int task_prio(const struct task_struct *p)
3062{
3063 return p->prio - MAX_RT_PRIO;
3064}
3065
3066/**
3067 * idle_cpu - is a given cpu idle currently?
3068 * @cpu: the processor in question.
3069 *
3070 * Return: 1 if the CPU is currently idle. 0 otherwise.
3071 */
3072int idle_cpu(int cpu)
3073{
3074 struct rq *rq = cpu_rq(cpu);
3075
3076 if (rq->curr != rq->idle)
3077 return 0;
3078
3079 if (rq->nr_running)
3080 return 0;
3081
3082#ifdef CONFIG_SMP
3083 if (!llist_empty(&rq->wake_list))
3084 return 0;
3085#endif
3086
3087 return 1;
3088}
3089
3090/**
3091 * idle_task - return the idle task for a given cpu.
3092 * @cpu: the processor in question.
3093 *
3094 * Return: The idle task for the cpu @cpu.
3095 */
3096struct task_struct *idle_task(int cpu)
3097{
3098 return cpu_rq(cpu)->idle;
3099}
3100
3101/**
3102 * find_process_by_pid - find a process with a matching PID value.
3103 * @pid: the pid in question.
3104 *
3105 * The task of @pid, if found. %NULL otherwise.
3106 */
3107static struct task_struct *find_process_by_pid(pid_t pid)
3108{
3109 return pid ? find_task_by_vpid(pid) : current;
3110}
3111
3112/*
3113 * This function initializes the sched_dl_entity of a newly becoming
3114 * SCHED_DEADLINE task.
3115 *
3116 * Only the static values are considered here, the actual runtime and the
3117 * absolute deadline will be properly calculated when the task is enqueued
3118 * for the first time with its new policy.
3119 */
3120static void
3121__setparam_dl(struct task_struct *p, const struct sched_attr *attr)
3122{
3123 struct sched_dl_entity *dl_se = &p->dl;
3124
3125 init_dl_task_timer(dl_se);
3126 dl_se->dl_runtime = attr->sched_runtime;
3127 dl_se->dl_deadline = attr->sched_deadline;
3128 dl_se->dl_period = attr->sched_period ?: dl_se->dl_deadline;
3129 dl_se->flags = attr->sched_flags;
3130 dl_se->dl_bw = to_ratio(dl_se->dl_period, dl_se->dl_runtime);
3131 dl_se->dl_throttled = 0;
3132 dl_se->dl_new = 1;
3133 dl_se->dl_yielded = 0;
3134}
3135
3136static void __setscheduler_params(struct task_struct *p,
3137 const struct sched_attr *attr)
3138{
3139 int policy = attr->sched_policy;
3140
3141 if (policy == -1) /* setparam */
3142 policy = p->policy;
3143
3144 p->policy = policy;
3145
3146 if (dl_policy(policy))
3147 __setparam_dl(p, attr);
3148 else if (fair_policy(policy))
3149 p->static_prio = NICE_TO_PRIO(attr->sched_nice);
3150
3151 /*
3152 * __sched_setscheduler() ensures attr->sched_priority == 0 when
3153 * !rt_policy. Always setting this ensures that things like
3154 * getparam()/getattr() don't report silly values for !rt tasks.
3155 */
3156 p->rt_priority = attr->sched_priority;
3157 p->normal_prio = normal_prio(p);
3158 set_load_weight(p);
3159}
3160
3161/* Actually do priority change: must hold pi & rq lock. */
3162static void __setscheduler(struct rq *rq, struct task_struct *p,
3163 const struct sched_attr *attr)
3164{
3165 __setscheduler_params(p, attr);
3166
3167 /*
3168 * If we get here, there was no pi waiters boosting the
3169 * task. It is safe to use the normal prio.
3170 */
3171 p->prio = normal_prio(p);
3172
3173 if (dl_prio(p->prio))
3174 p->sched_class = &dl_sched_class;
3175 else if (rt_prio(p->prio))
3176 p->sched_class = &rt_sched_class;
3177 else
3178 p->sched_class = &fair_sched_class;
3179}
3180
3181static void
3182__getparam_dl(struct task_struct *p, struct sched_attr *attr)
3183{
3184 struct sched_dl_entity *dl_se = &p->dl;
3185
3186 attr->sched_priority = p->rt_priority;
3187 attr->sched_runtime = dl_se->dl_runtime;
3188 attr->sched_deadline = dl_se->dl_deadline;
3189 attr->sched_period = dl_se->dl_period;
3190 attr->sched_flags = dl_se->flags;
3191}
3192
3193/*
3194 * This function validates the new parameters of a -deadline task.
3195 * We ask for the deadline not being zero, and greater or equal
3196 * than the runtime, as well as the period of being zero or
3197 * greater than deadline. Furthermore, we have to be sure that
3198 * user parameters are above the internal resolution of 1us (we
3199 * check sched_runtime only since it is always the smaller one) and
3200 * below 2^63 ns (we have to check both sched_deadline and
3201 * sched_period, as the latter can be zero).
3202 */
3203static bool
3204__checkparam_dl(const struct sched_attr *attr)
3205{
3206 /* deadline != 0 */
3207 if (attr->sched_deadline == 0)
3208 return false;
3209
3210 /*
3211 * Since we truncate DL_SCALE bits, make sure we're at least
3212 * that big.
3213 */
3214 if (attr->sched_runtime < (1ULL << DL_SCALE))
3215 return false;
3216
3217 /*
3218 * Since we use the MSB for wrap-around and sign issues, make
3219 * sure it's not set (mind that period can be equal to zero).
3220 */
3221 if (attr->sched_deadline & (1ULL << 63) ||
3222 attr->sched_period & (1ULL << 63))
3223 return false;
3224
3225 /* runtime <= deadline <= period (if period != 0) */
3226 if ((attr->sched_period != 0 &&
3227 attr->sched_period < attr->sched_deadline) ||
3228 attr->sched_deadline < attr->sched_runtime)
3229 return false;
3230
3231 return true;
3232}
3233
3234/*
3235 * check the target process has a UID that matches the current process's
3236 */
3237static bool check_same_owner(struct task_struct *p)
3238{
3239 const struct cred *cred = current_cred(), *pcred;
3240 bool match;
3241
3242 rcu_read_lock();
3243 pcred = __task_cred(p);
3244 match = (uid_eq(cred->euid, pcred->euid) ||
3245 uid_eq(cred->euid, pcred->uid));
3246 rcu_read_unlock();
3247 return match;
3248}
3249
3250static int __sched_setscheduler(struct task_struct *p,
3251 const struct sched_attr *attr,
3252 bool user)
3253{
3254 int newprio = dl_policy(attr->sched_policy) ? MAX_DL_PRIO - 1 :
3255 MAX_RT_PRIO - 1 - attr->sched_priority;
3256 int retval, oldprio, oldpolicy = -1, on_rq, running;
3257 int policy = attr->sched_policy;
3258 unsigned long flags;
3259 const struct sched_class *prev_class;
3260 struct rq *rq;
3261 int reset_on_fork;
3262
3263 /* may grab non-irq protected spin_locks */
3264 BUG_ON(in_interrupt());
3265recheck:
3266 /* double check policy once rq lock held */
3267 if (policy < 0) {
3268 reset_on_fork = p->sched_reset_on_fork;
3269 policy = oldpolicy = p->policy;
3270 } else {
3271 reset_on_fork = !!(attr->sched_flags & SCHED_FLAG_RESET_ON_FORK);
3272
3273 if (policy != SCHED_DEADLINE &&
3274 policy != SCHED_FIFO && policy != SCHED_RR &&
3275 policy != SCHED_NORMAL && policy != SCHED_BATCH &&
3276 policy != SCHED_IDLE)
3277 return -EINVAL;
3278 }
3279
3280 if (attr->sched_flags & ~(SCHED_FLAG_RESET_ON_FORK))
3281 return -EINVAL;
3282
3283 /*
3284 * Valid priorities for SCHED_FIFO and SCHED_RR are
3285 * 1..MAX_USER_RT_PRIO-1, valid priority for SCHED_NORMAL,
3286 * SCHED_BATCH and SCHED_IDLE is 0.
3287 */
3288 if ((p->mm && attr->sched_priority > MAX_USER_RT_PRIO-1) ||
3289 (!p->mm && attr->sched_priority > MAX_RT_PRIO-1))
3290 return -EINVAL;
3291 if ((dl_policy(policy) && !__checkparam_dl(attr)) ||
3292 (rt_policy(policy) != (attr->sched_priority != 0)))
3293 return -EINVAL;
3294
3295 /*
3296 * Allow unprivileged RT tasks to decrease priority:
3297 */
3298 if (user && !capable(CAP_SYS_NICE)) {
3299 if (fair_policy(policy)) {
3300 if (attr->sched_nice < task_nice(p) &&
3301 !can_nice(p, attr->sched_nice))
3302 return -EPERM;
3303 }
3304
3305 if (rt_policy(policy)) {
3306 unsigned long rlim_rtprio =
3307 task_rlimit(p, RLIMIT_RTPRIO);
3308
3309 /* can't set/change the rt policy */
3310 if (policy != p->policy && !rlim_rtprio)
3311 return -EPERM;
3312
3313 /* can't increase priority */
3314 if (attr->sched_priority > p->rt_priority &&
3315 attr->sched_priority > rlim_rtprio)
3316 return -EPERM;
3317 }
3318
3319 /*
3320 * Can't set/change SCHED_DEADLINE policy at all for now
3321 * (safest behavior); in the future we would like to allow
3322 * unprivileged DL tasks to increase their relative deadline
3323 * or reduce their runtime (both ways reducing utilization)
3324 */
3325 if (dl_policy(policy))
3326 return -EPERM;
3327
3328 /*
3329 * Treat SCHED_IDLE as nice 20. Only allow a switch to
3330 * SCHED_NORMAL if the RLIMIT_NICE would normally permit it.
3331 */
3332 if (p->policy == SCHED_IDLE && policy != SCHED_IDLE) {
3333 if (!can_nice(p, task_nice(p)))
3334 return -EPERM;
3335 }
3336
3337 /* can't change other user's priorities */
3338 if (!check_same_owner(p))
3339 return -EPERM;
3340
3341 /* Normal users shall not reset the sched_reset_on_fork flag */
3342 if (p->sched_reset_on_fork && !reset_on_fork)
3343 return -EPERM;
3344 }
3345
3346 if (user) {
3347 retval = security_task_setscheduler(p);
3348 if (retval)
3349 return retval;
3350 }
3351
3352 /*
3353 * make sure no PI-waiters arrive (or leave) while we are
3354 * changing the priority of the task:
3355 *
3356 * To be able to change p->policy safely, the appropriate
3357 * runqueue lock must be held.
3358 */
3359 rq = task_rq_lock(p, &flags);
3360
3361 /*
3362 * Changing the policy of the stop threads its a very bad idea
3363 */
3364 if (p == rq->stop) {
3365 task_rq_unlock(rq, p, &flags);
3366 return -EINVAL;
3367 }
3368
3369 /*
3370 * If not changing anything there's no need to proceed further,
3371 * but store a possible modification of reset_on_fork.
3372 */
3373 if (unlikely(policy == p->policy)) {
3374 if (fair_policy(policy) && attr->sched_nice != task_nice(p))
3375 goto change;
3376 if (rt_policy(policy) && attr->sched_priority != p->rt_priority)
3377 goto change;
3378 if (dl_policy(policy))
3379 goto change;
3380
3381 p->sched_reset_on_fork = reset_on_fork;
3382 task_rq_unlock(rq, p, &flags);
3383 return 0;
3384 }
3385change:
3386
3387 if (user) {
3388#ifdef CONFIG_RT_GROUP_SCHED
3389 /*
3390 * Do not allow realtime tasks into groups that have no runtime
3391 * assigned.
3392 */
3393 if (rt_bandwidth_enabled() && rt_policy(policy) &&
3394 task_group(p)->rt_bandwidth.rt_runtime == 0 &&
3395 !task_group_is_autogroup(task_group(p))) {
3396 task_rq_unlock(rq, p, &flags);
3397 return -EPERM;
3398 }
3399#endif
3400#ifdef CONFIG_SMP
3401 if (dl_bandwidth_enabled() && dl_policy(policy)) {
3402 cpumask_t *span = rq->rd->span;
3403
3404 /*
3405 * Don't allow tasks with an affinity mask smaller than
3406 * the entire root_domain to become SCHED_DEADLINE. We
3407 * will also fail if there's no bandwidth available.
3408 */
3409 if (!cpumask_subset(span, &p->cpus_allowed) ||
3410 rq->rd->dl_bw.bw == 0) {
3411 task_rq_unlock(rq, p, &flags);
3412 return -EPERM;
3413 }
3414 }
3415#endif
3416 }
3417
3418 /* recheck policy now with rq lock held */
3419 if (unlikely(oldpolicy != -1 && oldpolicy != p->policy)) {
3420 policy = oldpolicy = -1;
3421 task_rq_unlock(rq, p, &flags);
3422 goto recheck;
3423 }
3424
3425 /*
3426 * If setscheduling to SCHED_DEADLINE (or changing the parameters
3427 * of a SCHED_DEADLINE task) we need to check if enough bandwidth
3428 * is available.
3429 */
3430 if ((dl_policy(policy) || dl_task(p)) && dl_overflow(p, policy, attr)) {
3431 task_rq_unlock(rq, p, &flags);
3432 return -EBUSY;
3433 }
3434
3435 p->sched_reset_on_fork = reset_on_fork;
3436 oldprio = p->prio;
3437
3438 /*
3439 * Special case for priority boosted tasks.
3440 *
3441 * If the new priority is lower or equal (user space view)
3442 * than the current (boosted) priority, we just store the new
3443 * normal parameters and do not touch the scheduler class and
3444 * the runqueue. This will be done when the task deboost
3445 * itself.
3446 */
3447 if (rt_mutex_check_prio(p, newprio)) {
3448 __setscheduler_params(p, attr);
3449 task_rq_unlock(rq, p, &flags);
3450 return 0;
3451 }
3452
3453 on_rq = p->on_rq;
3454 running = task_current(rq, p);
3455 if (on_rq)
3456 dequeue_task(rq, p, 0);
3457 if (running)
3458 p->sched_class->put_prev_task(rq, p);
3459
3460 prev_class = p->sched_class;
3461 __setscheduler(rq, p, attr);
3462
3463 if (running)
3464 p->sched_class->set_curr_task(rq);
3465 if (on_rq) {
3466 /*
3467 * We enqueue to tail when the priority of a task is
3468 * increased (user space view).
3469 */
3470 enqueue_task(rq, p, oldprio <= p->prio ? ENQUEUE_HEAD : 0);
3471 }
3472
3473 check_class_changed(rq, p, prev_class, oldprio);
3474 task_rq_unlock(rq, p, &flags);
3475
3476 rt_mutex_adjust_pi(p);
3477
3478 return 0;
3479}
3480
3481static int _sched_setscheduler(struct task_struct *p, int policy,
3482 const struct sched_param *param, bool check)
3483{
3484 struct sched_attr attr = {
3485 .sched_policy = policy,
3486 .sched_priority = param->sched_priority,
3487 .sched_nice = PRIO_TO_NICE(p->static_prio),
3488 };
3489
3490 /*
3491 * Fixup the legacy SCHED_RESET_ON_FORK hack
3492 */
3493 if (policy & SCHED_RESET_ON_FORK) {
3494 attr.sched_flags |= SCHED_FLAG_RESET_ON_FORK;
3495 policy &= ~SCHED_RESET_ON_FORK;
3496 attr.sched_policy = policy;
3497 }
3498
3499 return __sched_setscheduler(p, &attr, check);
3500}
3501/**
3502 * sched_setscheduler - change the scheduling policy and/or RT priority of a thread.
3503 * @p: the task in question.
3504 * @policy: new policy.
3505 * @param: structure containing the new RT priority.
3506 *
3507 * Return: 0 on success. An error code otherwise.
3508 *
3509 * NOTE that the task may be already dead.
3510 */
3511int sched_setscheduler(struct task_struct *p, int policy,
3512 const struct sched_param *param)
3513{
3514 return _sched_setscheduler(p, policy, param, true);
3515}
3516EXPORT_SYMBOL_GPL(sched_setscheduler);
3517
3518int sched_setattr(struct task_struct *p, const struct sched_attr *attr)
3519{
3520 return __sched_setscheduler(p, attr, true);
3521}
3522EXPORT_SYMBOL_GPL(sched_setattr);
3523
3524/**
3525 * sched_setscheduler_nocheck - change the scheduling policy and/or RT priority of a thread from kernelspace.
3526 * @p: the task in question.
3527 * @policy: new policy.
3528 * @param: structure containing the new RT priority.
3529 *
3530 * Just like sched_setscheduler, only don't bother checking if the
3531 * current context has permission. For example, this is needed in
3532 * stop_machine(): we create temporary high priority worker threads,
3533 * but our caller might not have that capability.
3534 *
3535 * Return: 0 on success. An error code otherwise.
3536 */
3537int sched_setscheduler_nocheck(struct task_struct *p, int policy,
3538 const struct sched_param *param)
3539{
3540 return _sched_setscheduler(p, policy, param, false);
3541}
3542
3543static int
3544do_sched_setscheduler(pid_t pid, int policy, struct sched_param __user *param)
3545{
3546 struct sched_param lparam;
3547 struct task_struct *p;
3548 int retval;
3549
3550 if (!param || pid < 0)
3551 return -EINVAL;
3552 if (copy_from_user(&lparam, param, sizeof(struct sched_param)))
3553 return -EFAULT;
3554
3555 rcu_read_lock();
3556 retval = -ESRCH;
3557 p = find_process_by_pid(pid);
3558 if (p != NULL)
3559 retval = sched_setscheduler(p, policy, &lparam);
3560 rcu_read_unlock();
3561
3562 return retval;
3563}
3564
3565/*
3566 * Mimics kernel/events/core.c perf_copy_attr().
3567 */
3568static int sched_copy_attr(struct sched_attr __user *uattr,
3569 struct sched_attr *attr)
3570{
3571 u32 size;
3572 int ret;
3573
3574 if (!access_ok(VERIFY_WRITE, uattr, SCHED_ATTR_SIZE_VER0))
3575 return -EFAULT;
3576
3577 /*
3578 * zero the full structure, so that a short copy will be nice.
3579 */
3580 memset(attr, 0, sizeof(*attr));
3581
3582 ret = get_user(size, &uattr->size);
3583 if (ret)
3584 return ret;
3585
3586 if (size > PAGE_SIZE) /* silly large */
3587 goto err_size;
3588
3589 if (!size) /* abi compat */
3590 size = SCHED_ATTR_SIZE_VER0;
3591
3592 if (size < SCHED_ATTR_SIZE_VER0)
3593 goto err_size;
3594
3595 /*
3596 * If we're handed a bigger struct than we know of,
3597 * ensure all the unknown bits are 0 - i.e. new
3598 * user-space does not rely on any kernel feature
3599 * extensions we dont know about yet.
3600 */
3601 if (size > sizeof(*attr)) {
3602 unsigned char __user *addr;
3603 unsigned char __user *end;
3604 unsigned char val;
3605
3606 addr = (void __user *)uattr + sizeof(*attr);
3607 end = (void __user *)uattr + size;
3608
3609 for (; addr < end; addr++) {
3610 ret = get_user(val, addr);
3611 if (ret)
3612 return ret;
3613 if (val)
3614 goto err_size;
3615 }
3616 size = sizeof(*attr);
3617 }
3618
3619 ret = copy_from_user(attr, uattr, size);
3620 if (ret)
3621 return -EFAULT;
3622
3623 /*
3624 * XXX: do we want to be lenient like existing syscalls; or do we want
3625 * to be strict and return an error on out-of-bounds values?
3626 */
3627 attr->sched_nice = clamp(attr->sched_nice, MIN_NICE, MAX_NICE);
3628
3629out:
3630 return ret;
3631
3632err_size:
3633 put_user(sizeof(*attr), &uattr->size);
3634 ret = -E2BIG;
3635 goto out;
3636}
3637
3638/**
3639 * sys_sched_setscheduler - set/change the scheduler policy and RT priority
3640 * @pid: the pid in question.
3641 * @policy: new policy.
3642 * @param: structure containing the new RT priority.
3643 *
3644 * Return: 0 on success. An error code otherwise.
3645 */
3646SYSCALL_DEFINE3(sched_setscheduler, pid_t, pid, int, policy,
3647 struct sched_param __user *, param)
3648{
3649 /* negative values for policy are not valid */
3650 if (policy < 0)
3651 return -EINVAL;
3652
3653 return do_sched_setscheduler(pid, policy, param);
3654}
3655
3656/**
3657 * sys_sched_setparam - set/change the RT priority of a thread
3658 * @pid: the pid in question.
3659 * @param: structure containing the new RT priority.
3660 *
3661 * Return: 0 on success. An error code otherwise.
3662 */
3663SYSCALL_DEFINE2(sched_setparam, pid_t, pid, struct sched_param __user *, param)
3664{
3665 return do_sched_setscheduler(pid, -1, param);
3666}
3667
3668/**
3669 * sys_sched_setattr - same as above, but with extended sched_attr
3670 * @pid: the pid in question.
3671 * @uattr: structure containing the extended parameters.
3672 * @flags: for future extension.
3673 */
3674SYSCALL_DEFINE3(sched_setattr, pid_t, pid, struct sched_attr __user *, uattr,
3675 unsigned int, flags)
3676{
3677 struct sched_attr attr;
3678 struct task_struct *p;
3679 int retval;
3680
3681 if (!uattr || pid < 0 || flags)
3682 return -EINVAL;
3683
3684 retval = sched_copy_attr(uattr, &attr);
3685 if (retval)
3686 return retval;
3687
3688 if ((int)attr.sched_policy < 0)
3689 return -EINVAL;
3690
3691 rcu_read_lock();
3692 retval = -ESRCH;
3693 p = find_process_by_pid(pid);
3694 if (p != NULL)
3695 retval = sched_setattr(p, &attr);
3696 rcu_read_unlock();
3697
3698 return retval;
3699}
3700
3701/**
3702 * sys_sched_getscheduler - get the policy (scheduling class) of a thread
3703 * @pid: the pid in question.
3704 *
3705 * Return: On success, the policy of the thread. Otherwise, a negative error
3706 * code.
3707 */
3708SYSCALL_DEFINE1(sched_getscheduler, pid_t, pid)
3709{
3710 struct task_struct *p;
3711 int retval;
3712
3713 if (pid < 0)
3714 return -EINVAL;
3715
3716 retval = -ESRCH;
3717 rcu_read_lock();
3718 p = find_process_by_pid(pid);
3719 if (p) {
3720 retval = security_task_getscheduler(p);
3721 if (!retval)
3722 retval = p->policy
3723 | (p->sched_reset_on_fork ? SCHED_RESET_ON_FORK : 0);
3724 }
3725 rcu_read_unlock();
3726 return retval;
3727}
3728
3729/**
3730 * sys_sched_getparam - get the RT priority of a thread
3731 * @pid: the pid in question.
3732 * @param: structure containing the RT priority.
3733 *
3734 * Return: On success, 0 and the RT priority is in @param. Otherwise, an error
3735 * code.
3736 */
3737SYSCALL_DEFINE2(sched_getparam, pid_t, pid, struct sched_param __user *, param)
3738{
3739 struct sched_param lp = { .sched_priority = 0 };
3740 struct task_struct *p;
3741 int retval;
3742
3743 if (!param || pid < 0)
3744 return -EINVAL;
3745
3746 rcu_read_lock();
3747 p = find_process_by_pid(pid);
3748 retval = -ESRCH;
3749 if (!p)
3750 goto out_unlock;
3751
3752 retval = security_task_getscheduler(p);
3753 if (retval)
3754 goto out_unlock;
3755
3756 if (task_has_rt_policy(p))
3757 lp.sched_priority = p->rt_priority;
3758 rcu_read_unlock();
3759
3760 /*
3761 * This one might sleep, we cannot do it with a spinlock held ...
3762 */
3763 retval = copy_to_user(param, &lp, sizeof(*param)) ? -EFAULT : 0;
3764
3765 return retval;
3766
3767out_unlock:
3768 rcu_read_unlock();
3769 return retval;
3770}
3771
3772static int sched_read_attr(struct sched_attr __user *uattr,
3773 struct sched_attr *attr,
3774 unsigned int usize)
3775{
3776 int ret;
3777
3778 if (!access_ok(VERIFY_WRITE, uattr, usize))
3779 return -EFAULT;
3780
3781 /*
3782 * If we're handed a smaller struct than we know of,
3783 * ensure all the unknown bits are 0 - i.e. old
3784 * user-space does not get uncomplete information.
3785 */
3786 if (usize < sizeof(*attr)) {
3787 unsigned char *addr;
3788 unsigned char *end;
3789
3790 addr = (void *)attr + usize;
3791 end = (void *)attr + sizeof(*attr);
3792
3793 for (; addr < end; addr++) {
3794 if (*addr)
3795 goto err_size;
3796 }
3797
3798 attr->size = usize;
3799 }
3800
3801 ret = copy_to_user(uattr, attr, attr->size);
3802 if (ret)
3803 return -EFAULT;
3804
3805out:
3806 return ret;
3807
3808err_size:
3809 ret = -E2BIG;
3810 goto out;
3811}
3812
3813/**
3814 * sys_sched_getattr - similar to sched_getparam, but with sched_attr
3815 * @pid: the pid in question.
3816 * @uattr: structure containing the extended parameters.
3817 * @size: sizeof(attr) for fwd/bwd comp.
3818 * @flags: for future extension.
3819 */
3820SYSCALL_DEFINE4(sched_getattr, pid_t, pid, struct sched_attr __user *, uattr,
3821 unsigned int, size, unsigned int, flags)
3822{
3823 struct sched_attr attr = {
3824 .size = sizeof(struct sched_attr),
3825 };
3826 struct task_struct *p;
3827 int retval;
3828
3829 if (!uattr || pid < 0 || size > PAGE_SIZE ||
3830 size < SCHED_ATTR_SIZE_VER0 || flags)
3831 return -EINVAL;
3832
3833 rcu_read_lock();
3834 p = find_process_by_pid(pid);
3835 retval = -ESRCH;
3836 if (!p)
3837 goto out_unlock;
3838
3839 retval = security_task_getscheduler(p);
3840 if (retval)
3841 goto out_unlock;
3842
3843 attr.sched_policy = p->policy;
3844 if (p->sched_reset_on_fork)
3845 attr.sched_flags |= SCHED_FLAG_RESET_ON_FORK;
3846 if (task_has_dl_policy(p))
3847 __getparam_dl(p, &attr);
3848 else if (task_has_rt_policy(p))
3849 attr.sched_priority = p->rt_priority;
3850 else
3851 attr.sched_nice = task_nice(p);
3852
3853 rcu_read_unlock();
3854
3855 retval = sched_read_attr(uattr, &attr, size);
3856 return retval;
3857
3858out_unlock:
3859 rcu_read_unlock();
3860 return retval;
3861}
3862
3863long sched_setaffinity(pid_t pid, const struct cpumask *in_mask)
3864{
3865 cpumask_var_t cpus_allowed, new_mask;
3866 struct task_struct *p;
3867 int retval;
3868
3869 rcu_read_lock();
3870
3871 p = find_process_by_pid(pid);
3872 if (!p) {
3873 rcu_read_unlock();
3874 return -ESRCH;
3875 }
3876
3877 /* Prevent p going away */
3878 get_task_struct(p);
3879 rcu_read_unlock();
3880
3881 if (p->flags & PF_NO_SETAFFINITY) {
3882 retval = -EINVAL;
3883 goto out_put_task;
3884 }
3885 if (!alloc_cpumask_var(&cpus_allowed, GFP_KERNEL)) {
3886 retval = -ENOMEM;
3887 goto out_put_task;
3888 }
3889 if (!alloc_cpumask_var(&new_mask, GFP_KERNEL)) {
3890 retval = -ENOMEM;
3891 goto out_free_cpus_allowed;
3892 }
3893 retval = -EPERM;
3894 if (!check_same_owner(p)) {
3895 rcu_read_lock();
3896 if (!ns_capable(__task_cred(p)->user_ns, CAP_SYS_NICE)) {
3897 rcu_read_unlock();
3898 goto out_unlock;
3899 }
3900 rcu_read_unlock();
3901 }
3902
3903 retval = security_task_setscheduler(p);
3904 if (retval)
3905 goto out_unlock;
3906
3907
3908 cpuset_cpus_allowed(p, cpus_allowed);
3909 cpumask_and(new_mask, in_mask, cpus_allowed);
3910
3911 /*
3912 * Since bandwidth control happens on root_domain basis,
3913 * if admission test is enabled, we only admit -deadline
3914 * tasks allowed to run on all the CPUs in the task's
3915 * root_domain.
3916 */
3917#ifdef CONFIG_SMP
3918 if (task_has_dl_policy(p)) {
3919 const struct cpumask *span = task_rq(p)->rd->span;
3920
3921 if (dl_bandwidth_enabled() && !cpumask_subset(span, new_mask)) {
3922 retval = -EBUSY;
3923 goto out_unlock;
3924 }
3925 }
3926#endif
3927again:
3928 retval = set_cpus_allowed_ptr(p, new_mask);
3929
3930 if (!retval) {
3931 cpuset_cpus_allowed(p, cpus_allowed);
3932 if (!cpumask_subset(new_mask, cpus_allowed)) {
3933 /*
3934 * We must have raced with a concurrent cpuset
3935 * update. Just reset the cpus_allowed to the
3936 * cpuset's cpus_allowed
3937 */
3938 cpumask_copy(new_mask, cpus_allowed);
3939 goto again;
3940 }
3941 }
3942out_unlock:
3943 free_cpumask_var(new_mask);
3944out_free_cpus_allowed:
3945 free_cpumask_var(cpus_allowed);
3946out_put_task:
3947 put_task_struct(p);
3948 return retval;
3949}
3950
3951static int get_user_cpu_mask(unsigned long __user *user_mask_ptr, unsigned len,
3952 struct cpumask *new_mask)
3953{
3954 if (len < cpumask_size())
3955 cpumask_clear(new_mask);
3956 else if (len > cpumask_size())
3957 len = cpumask_size();
3958
3959 return copy_from_user(new_mask, user_mask_ptr, len) ? -EFAULT : 0;
3960}
3961
3962/**
3963 * sys_sched_setaffinity - set the cpu affinity of a process
3964 * @pid: pid of the process
3965 * @len: length in bytes of the bitmask pointed to by user_mask_ptr
3966 * @user_mask_ptr: user-space pointer to the new cpu mask
3967 *
3968 * Return: 0 on success. An error code otherwise.
3969 */
3970SYSCALL_DEFINE3(sched_setaffinity, pid_t, pid, unsigned int, len,
3971 unsigned long __user *, user_mask_ptr)
3972{
3973 cpumask_var_t new_mask;
3974 int retval;
3975
3976 if (!alloc_cpumask_var(&new_mask, GFP_KERNEL))
3977 return -ENOMEM;
3978
3979 retval = get_user_cpu_mask(user_mask_ptr, len, new_mask);
3980 if (retval == 0)
3981 retval = sched_setaffinity(pid, new_mask);
3982 free_cpumask_var(new_mask);
3983 return retval;
3984}
3985
3986long sched_getaffinity(pid_t pid, struct cpumask *mask)
3987{
3988 struct task_struct *p;
3989 unsigned long flags;
3990 int retval;
3991
3992 rcu_read_lock();
3993
3994 retval = -ESRCH;
3995 p = find_process_by_pid(pid);
3996 if (!p)
3997 goto out_unlock;
3998
3999 retval = security_task_getscheduler(p);
4000 if (retval)
4001 goto out_unlock;
4002
4003 raw_spin_lock_irqsave(&p->pi_lock, flags);
4004 cpumask_and(mask, &p->cpus_allowed, cpu_active_mask);
4005 raw_spin_unlock_irqrestore(&p->pi_lock, flags);
4006
4007out_unlock:
4008 rcu_read_unlock();
4009
4010 return retval;
4011}
4012
4013/**
4014 * sys_sched_getaffinity - get the cpu affinity of a process
4015 * @pid: pid of the process
4016 * @len: length in bytes of the bitmask pointed to by user_mask_ptr
4017 * @user_mask_ptr: user-space pointer to hold the current cpu mask
4018 *
4019 * Return: 0 on success. An error code otherwise.
4020 */
4021SYSCALL_DEFINE3(sched_getaffinity, pid_t, pid, unsigned int, len,
4022 unsigned long __user *, user_mask_ptr)
4023{
4024 int ret;
4025 cpumask_var_t mask;
4026
4027 if ((len * BITS_PER_BYTE) < nr_cpu_ids)
4028 return -EINVAL;
4029 if (len & (sizeof(unsigned long)-1))
4030 return -EINVAL;
4031
4032 if (!alloc_cpumask_var(&mask, GFP_KERNEL))
4033 return -ENOMEM;
4034
4035 ret = sched_getaffinity(pid, mask);
4036 if (ret == 0) {
4037 size_t retlen = min_t(size_t, len, cpumask_size());
4038
4039 if (copy_to_user(user_mask_ptr, mask, retlen))
4040 ret = -EFAULT;
4041 else
4042 ret = retlen;
4043 }
4044 free_cpumask_var(mask);
4045
4046 return ret;
4047}
4048
4049/**
4050 * sys_sched_yield - yield the current processor to other threads.
4051 *
4052 * This function yields the current CPU to other tasks. If there are no
4053 * other threads running on this CPU then this function will return.
4054 *
4055 * Return: 0.
4056 */
4057SYSCALL_DEFINE0(sched_yield)
4058{
4059 struct rq *rq = this_rq_lock();
4060
4061 schedstat_inc(rq, yld_count);
4062 current->sched_class->yield_task(rq);
4063
4064 /*
4065 * Since we are going to call schedule() anyway, there's
4066 * no need to preempt or enable interrupts:
4067 */
4068 __release(rq->lock);
4069 spin_release(&rq->lock.dep_map, 1, _THIS_IP_);
4070 do_raw_spin_unlock(&rq->lock);
4071 sched_preempt_enable_no_resched();
4072
4073 schedule();
4074
4075 return 0;
4076}
4077
4078static void __cond_resched(void)
4079{
4080 __preempt_count_add(PREEMPT_ACTIVE);
4081 __schedule();
4082 __preempt_count_sub(PREEMPT_ACTIVE);
4083}
4084
4085int __sched _cond_resched(void)
4086{
4087 if (should_resched()) {
4088 __cond_resched();
4089 return 1;
4090 }
4091 return 0;
4092}
4093EXPORT_SYMBOL(_cond_resched);
4094
4095/*
4096 * __cond_resched_lock() - if a reschedule is pending, drop the given lock,
4097 * call schedule, and on return reacquire the lock.
4098 *
4099 * This works OK both with and without CONFIG_PREEMPT. We do strange low-level
4100 * operations here to prevent schedule() from being called twice (once via
4101 * spin_unlock(), once by hand).
4102 */
4103int __cond_resched_lock(spinlock_t *lock)
4104{
4105 int resched = should_resched();
4106 int ret = 0;
4107
4108 lockdep_assert_held(lock);
4109
4110 if (spin_needbreak(lock) || resched) {
4111 spin_unlock(lock);
4112 if (resched)
4113 __cond_resched();
4114 else
4115 cpu_relax();
4116 ret = 1;
4117 spin_lock(lock);
4118 }
4119 return ret;
4120}
4121EXPORT_SYMBOL(__cond_resched_lock);
4122
4123int __sched __cond_resched_softirq(void)
4124{
4125 BUG_ON(!in_softirq());
4126
4127 if (should_resched()) {
4128 local_bh_enable();
4129 __cond_resched();
4130 local_bh_disable();
4131 return 1;
4132 }
4133 return 0;
4134}
4135EXPORT_SYMBOL(__cond_resched_softirq);
4136
4137/**
4138 * yield - yield the current processor to other threads.
4139 *
4140 * Do not ever use this function, there's a 99% chance you're doing it wrong.
4141 *
4142 * The scheduler is at all times free to pick the calling task as the most
4143 * eligible task to run, if removing the yield() call from your code breaks
4144 * it, its already broken.
4145 *
4146 * Typical broken usage is:
4147 *
4148 * while (!event)
4149 * yield();
4150 *
4151 * where one assumes that yield() will let 'the other' process run that will
4152 * make event true. If the current task is a SCHED_FIFO task that will never
4153 * happen. Never use yield() as a progress guarantee!!
4154 *
4155 * If you want to use yield() to wait for something, use wait_event().
4156 * If you want to use yield() to be 'nice' for others, use cond_resched().
4157 * If you still want to use yield(), do not!
4158 */
4159void __sched yield(void)
4160{
4161 set_current_state(TASK_RUNNING);
4162 sys_sched_yield();
4163}
4164EXPORT_SYMBOL(yield);
4165
4166/**
4167 * yield_to - yield the current processor to another thread in
4168 * your thread group, or accelerate that thread toward the
4169 * processor it's on.
4170 * @p: target task
4171 * @preempt: whether task preemption is allowed or not
4172 *
4173 * It's the caller's job to ensure that the target task struct
4174 * can't go away on us before we can do any checks.
4175 *
4176 * Return:
4177 * true (>0) if we indeed boosted the target task.
4178 * false (0) if we failed to boost the target.
4179 * -ESRCH if there's no task to yield to.
4180 */
4181bool __sched yield_to(struct task_struct *p, bool preempt)
4182{
4183 struct task_struct *curr = current;
4184 struct rq *rq, *p_rq;
4185 unsigned long flags;
4186 int yielded = 0;
4187
4188 local_irq_save(flags);
4189 rq = this_rq();
4190
4191again:
4192 p_rq = task_rq(p);
4193 /*
4194 * If we're the only runnable task on the rq and target rq also
4195 * has only one task, there's absolutely no point in yielding.
4196 */
4197 if (rq->nr_running == 1 && p_rq->nr_running == 1) {
4198 yielded = -ESRCH;
4199 goto out_irq;
4200 }
4201
4202 double_rq_lock(rq, p_rq);
4203 if (task_rq(p) != p_rq) {
4204 double_rq_unlock(rq, p_rq);
4205 goto again;
4206 }
4207
4208 if (!curr->sched_class->yield_to_task)
4209 goto out_unlock;
4210
4211 if (curr->sched_class != p->sched_class)
4212 goto out_unlock;
4213
4214 if (task_running(p_rq, p) || p->state)
4215 goto out_unlock;
4216
4217 yielded = curr->sched_class->yield_to_task(rq, p, preempt);
4218 if (yielded) {
4219 schedstat_inc(rq, yld_count);
4220 /*
4221 * Make p's CPU reschedule; pick_next_entity takes care of
4222 * fairness.
4223 */
4224 if (preempt && rq != p_rq)
4225 resched_task(p_rq->curr);
4226 }
4227
4228out_unlock:
4229 double_rq_unlock(rq, p_rq);
4230out_irq:
4231 local_irq_restore(flags);
4232
4233 if (yielded > 0)
4234 schedule();
4235
4236 return yielded;
4237}
4238EXPORT_SYMBOL_GPL(yield_to);
4239
4240/*
4241 * This task is about to go to sleep on IO. Increment rq->nr_iowait so
4242 * that process accounting knows that this is a task in IO wait state.
4243 */
4244void __sched io_schedule(void)
4245{
4246 struct rq *rq = raw_rq();
4247
4248 delayacct_blkio_start();
4249 atomic_inc(&rq->nr_iowait);
4250 blk_flush_plug(current);
4251 current->in_iowait = 1;
4252 schedule();
4253 current->in_iowait = 0;
4254 atomic_dec(&rq->nr_iowait);
4255 delayacct_blkio_end();
4256}
4257EXPORT_SYMBOL(io_schedule);
4258
4259long __sched io_schedule_timeout(long timeout)
4260{
4261 struct rq *rq = raw_rq();
4262 long ret;
4263
4264 delayacct_blkio_start();
4265 atomic_inc(&rq->nr_iowait);
4266 blk_flush_plug(current);
4267 current->in_iowait = 1;
4268 ret = schedule_timeout(timeout);
4269 current->in_iowait = 0;
4270 atomic_dec(&rq->nr_iowait);
4271 delayacct_blkio_end();
4272 return ret;
4273}
4274
4275/**
4276 * sys_sched_get_priority_max - return maximum RT priority.
4277 * @policy: scheduling class.
4278 *
4279 * Return: On success, this syscall returns the maximum
4280 * rt_priority that can be used by a given scheduling class.
4281 * On failure, a negative error code is returned.
4282 */
4283SYSCALL_DEFINE1(sched_get_priority_max, int, policy)
4284{
4285 int ret = -EINVAL;
4286
4287 switch (policy) {
4288 case SCHED_FIFO:
4289 case SCHED_RR:
4290 ret = MAX_USER_RT_PRIO-1;
4291 break;
4292 case SCHED_DEADLINE:
4293 case SCHED_NORMAL:
4294 case SCHED_BATCH:
4295 case SCHED_IDLE:
4296 ret = 0;
4297 break;
4298 }
4299 return ret;
4300}
4301
4302/**
4303 * sys_sched_get_priority_min - return minimum RT priority.
4304 * @policy: scheduling class.
4305 *
4306 * Return: On success, this syscall returns the minimum
4307 * rt_priority that can be used by a given scheduling class.
4308 * On failure, a negative error code is returned.
4309 */
4310SYSCALL_DEFINE1(sched_get_priority_min, int, policy)
4311{
4312 int ret = -EINVAL;
4313
4314 switch (policy) {
4315 case SCHED_FIFO:
4316 case SCHED_RR:
4317 ret = 1;
4318 break;
4319 case SCHED_DEADLINE:
4320 case SCHED_NORMAL:
4321 case SCHED_BATCH:
4322 case SCHED_IDLE:
4323 ret = 0;
4324 }
4325 return ret;
4326}
4327
4328/**
4329 * sys_sched_rr_get_interval - return the default timeslice of a process.
4330 * @pid: pid of the process.
4331 * @interval: userspace pointer to the timeslice value.
4332 *
4333 * this syscall writes the default timeslice value of a given process
4334 * into the user-space timespec buffer. A value of '0' means infinity.
4335 *
4336 * Return: On success, 0 and the timeslice is in @interval. Otherwise,
4337 * an error code.
4338 */
4339SYSCALL_DEFINE2(sched_rr_get_interval, pid_t, pid,
4340 struct timespec __user *, interval)
4341{
4342 struct task_struct *p;
4343 unsigned int time_slice;
4344 unsigned long flags;
4345 struct rq *rq;
4346 int retval;
4347 struct timespec t;
4348
4349 if (pid < 0)
4350 return -EINVAL;
4351
4352 retval = -ESRCH;
4353 rcu_read_lock();
4354 p = find_process_by_pid(pid);
4355 if (!p)
4356 goto out_unlock;
4357
4358 retval = security_task_getscheduler(p);
4359 if (retval)
4360 goto out_unlock;
4361
4362 rq = task_rq_lock(p, &flags);
4363 time_slice = 0;
4364 if (p->sched_class->get_rr_interval)
4365 time_slice = p->sched_class->get_rr_interval(rq, p);
4366 task_rq_unlock(rq, p, &flags);
4367
4368 rcu_read_unlock();
4369 jiffies_to_timespec(time_slice, &t);
4370 retval = copy_to_user(interval, &t, sizeof(t)) ? -EFAULT : 0;
4371 return retval;
4372
4373out_unlock:
4374 rcu_read_unlock();
4375 return retval;
4376}
4377
4378static const char stat_nam[] = TASK_STATE_TO_CHAR_STR;
4379
4380void sched_show_task(struct task_struct *p)
4381{
4382 unsigned long free = 0;
4383 int ppid;
4384 unsigned state;
4385
4386 state = p->state ? __ffs(p->state) + 1 : 0;
4387 printk(KERN_INFO "%-15.15s %c", p->comm,
4388 state < sizeof(stat_nam) - 1 ? stat_nam[state] : '?');
4389#if BITS_PER_LONG == 32
4390 if (state == TASK_RUNNING)
4391 printk(KERN_CONT " running ");
4392 else
4393 printk(KERN_CONT " %08lx ", thread_saved_pc(p));
4394#else
4395 if (state == TASK_RUNNING)
4396 printk(KERN_CONT " running task ");
4397 else
4398 printk(KERN_CONT " %016lx ", thread_saved_pc(p));
4399#endif
4400#ifdef CONFIG_DEBUG_STACK_USAGE
4401 free = stack_not_used(p);
4402#endif
4403 rcu_read_lock();
4404 ppid = task_pid_nr(rcu_dereference(p->real_parent));
4405 rcu_read_unlock();
4406 printk(KERN_CONT "%5lu %5d %6d 0x%08lx\n", free,
4407 task_pid_nr(p), ppid,
4408 (unsigned long)task_thread_info(p)->flags);
4409
4410 print_worker_info(KERN_INFO, p);
4411 show_stack(p, NULL);
4412}
4413
4414void show_state_filter(unsigned long state_filter)
4415{
4416 struct task_struct *g, *p;
4417
4418#if BITS_PER_LONG == 32
4419 printk(KERN_INFO
4420 " task PC stack pid father\n");
4421#else
4422 printk(KERN_INFO
4423 " task PC stack pid father\n");
4424#endif
4425 rcu_read_lock();
4426 do_each_thread(g, p) {
4427 /*
4428 * reset the NMI-timeout, listing all files on a slow
4429 * console might take a lot of time:
4430 */
4431 touch_nmi_watchdog();
4432 if (!state_filter || (p->state & state_filter))
4433 sched_show_task(p);
4434 } while_each_thread(g, p);
4435
4436 touch_all_softlockup_watchdogs();
4437
4438#ifdef CONFIG_SCHED_DEBUG
4439 sysrq_sched_debug_show();
4440#endif
4441 rcu_read_unlock();
4442 /*
4443 * Only show locks if all tasks are dumped:
4444 */
4445 if (!state_filter)
4446 debug_show_all_locks();
4447}
4448
4449void init_idle_bootup_task(struct task_struct *idle)
4450{
4451 idle->sched_class = &idle_sched_class;
4452}
4453
4454/**
4455 * init_idle - set up an idle thread for a given CPU
4456 * @idle: task in question
4457 * @cpu: cpu the idle task belongs to
4458 *
4459 * NOTE: this function does not set the idle thread's NEED_RESCHED
4460 * flag, to make booting more robust.
4461 */
4462void init_idle(struct task_struct *idle, int cpu)
4463{
4464 struct rq *rq = cpu_rq(cpu);
4465 unsigned long flags;
4466
4467 raw_spin_lock_irqsave(&rq->lock, flags);
4468
4469 __sched_fork(0, idle);
4470 idle->state = TASK_RUNNING;
4471 idle->se.exec_start = sched_clock();
4472
4473 do_set_cpus_allowed(idle, cpumask_of(cpu));
4474 /*
4475 * We're having a chicken and egg problem, even though we are
4476 * holding rq->lock, the cpu isn't yet set to this cpu so the
4477 * lockdep check in task_group() will fail.
4478 *
4479 * Similar case to sched_fork(). / Alternatively we could
4480 * use task_rq_lock() here and obtain the other rq->lock.
4481 *
4482 * Silence PROVE_RCU
4483 */
4484 rcu_read_lock();
4485 __set_task_cpu(idle, cpu);
4486 rcu_read_unlock();
4487
4488 rq->curr = rq->idle = idle;
4489 idle->on_rq = 1;
4490#if defined(CONFIG_SMP)
4491 idle->on_cpu = 1;
4492#endif
4493 raw_spin_unlock_irqrestore(&rq->lock, flags);
4494
4495 /* Set the preempt count _outside_ the spinlocks! */
4496 init_idle_preempt_count(idle, cpu);
4497
4498 /*
4499 * The idle tasks have their own, simple scheduling class:
4500 */
4501 idle->sched_class = &idle_sched_class;
4502 ftrace_graph_init_idle_task(idle, cpu);
4503 vtime_init_idle(idle, cpu);
4504#if defined(CONFIG_SMP)
4505 sprintf(idle->comm, "%s/%d", INIT_TASK_COMM, cpu);
4506#endif
4507}
4508
4509#ifdef CONFIG_SMP
4510void do_set_cpus_allowed(struct task_struct *p, const struct cpumask *new_mask)
4511{
4512 if (p->sched_class && p->sched_class->set_cpus_allowed)
4513 p->sched_class->set_cpus_allowed(p, new_mask);
4514
4515 cpumask_copy(&p->cpus_allowed, new_mask);
4516 p->nr_cpus_allowed = cpumask_weight(new_mask);
4517}
4518
4519/*
4520 * This is how migration works:
4521 *
4522 * 1) we invoke migration_cpu_stop() on the target CPU using
4523 * stop_one_cpu().
4524 * 2) stopper starts to run (implicitly forcing the migrated thread
4525 * off the CPU)
4526 * 3) it checks whether the migrated task is still in the wrong runqueue.
4527 * 4) if it's in the wrong runqueue then the migration thread removes
4528 * it and puts it into the right queue.
4529 * 5) stopper completes and stop_one_cpu() returns and the migration
4530 * is done.
4531 */
4532
4533/*
4534 * Change a given task's CPU affinity. Migrate the thread to a
4535 * proper CPU and schedule it away if the CPU it's executing on
4536 * is removed from the allowed bitmask.
4537 *
4538 * NOTE: the caller must have a valid reference to the task, the
4539 * task must not exit() & deallocate itself prematurely. The
4540 * call is not atomic; no spinlocks may be held.
4541 */
4542int set_cpus_allowed_ptr(struct task_struct *p, const struct cpumask *new_mask)
4543{
4544 unsigned long flags;
4545 struct rq *rq;
4546 unsigned int dest_cpu;
4547 int ret = 0;
4548
4549 rq = task_rq_lock(p, &flags);
4550
4551 if (cpumask_equal(&p->cpus_allowed, new_mask))
4552 goto out;
4553
4554 if (!cpumask_intersects(new_mask, cpu_active_mask)) {
4555 ret = -EINVAL;
4556 goto out;
4557 }
4558
4559 do_set_cpus_allowed(p, new_mask);
4560
4561 /* Can the task run on the task's current CPU? If so, we're done */
4562 if (cpumask_test_cpu(task_cpu(p), new_mask))
4563 goto out;
4564
4565 dest_cpu = cpumask_any_and(cpu_active_mask, new_mask);
4566 if (p->on_rq) {
4567 struct migration_arg arg = { p, dest_cpu };
4568 /* Need help from migration thread: drop lock and wait. */
4569 task_rq_unlock(rq, p, &flags);
4570 stop_one_cpu(cpu_of(rq), migration_cpu_stop, &arg);
4571 tlb_migrate_finish(p->mm);
4572 return 0;
4573 }
4574out:
4575 task_rq_unlock(rq, p, &flags);
4576
4577 return ret;
4578}
4579EXPORT_SYMBOL_GPL(set_cpus_allowed_ptr);
4580
4581/*
4582 * Move (not current) task off this cpu, onto dest cpu. We're doing
4583 * this because either it can't run here any more (set_cpus_allowed()
4584 * away from this CPU, or CPU going down), or because we're
4585 * attempting to rebalance this task on exec (sched_exec).
4586 *
4587 * So we race with normal scheduler movements, but that's OK, as long
4588 * as the task is no longer on this CPU.
4589 *
4590 * Returns non-zero if task was successfully migrated.
4591 */
4592static int __migrate_task(struct task_struct *p, int src_cpu, int dest_cpu)
4593{
4594 struct rq *rq_dest, *rq_src;
4595 int ret = 0;
4596
4597 if (unlikely(!cpu_active(dest_cpu)))
4598 return ret;
4599
4600 rq_src = cpu_rq(src_cpu);
4601 rq_dest = cpu_rq(dest_cpu);
4602
4603 raw_spin_lock(&p->pi_lock);
4604 double_rq_lock(rq_src, rq_dest);
4605 /* Already moved. */
4606 if (task_cpu(p) != src_cpu)
4607 goto done;
4608 /* Affinity changed (again). */
4609 if (!cpumask_test_cpu(dest_cpu, tsk_cpus_allowed(p)))
4610 goto fail;
4611
4612 /*
4613 * If we're not on a rq, the next wake-up will ensure we're
4614 * placed properly.
4615 */
4616 if (p->on_rq) {
4617 dequeue_task(rq_src, p, 0);
4618 set_task_cpu(p, dest_cpu);
4619 enqueue_task(rq_dest, p, 0);
4620 check_preempt_curr(rq_dest, p, 0);
4621 }
4622done:
4623 ret = 1;
4624fail:
4625 double_rq_unlock(rq_src, rq_dest);
4626 raw_spin_unlock(&p->pi_lock);
4627 return ret;
4628}
4629
4630#ifdef CONFIG_NUMA_BALANCING
4631/* Migrate current task p to target_cpu */
4632int migrate_task_to(struct task_struct *p, int target_cpu)
4633{
4634 struct migration_arg arg = { p, target_cpu };
4635 int curr_cpu = task_cpu(p);
4636
4637 if (curr_cpu == target_cpu)
4638 return 0;
4639
4640 if (!cpumask_test_cpu(target_cpu, tsk_cpus_allowed(p)))
4641 return -EINVAL;
4642
4643 /* TODO: This is not properly updating schedstats */
4644
4645 trace_sched_move_numa(p, curr_cpu, target_cpu);
4646 return stop_one_cpu(curr_cpu, migration_cpu_stop, &arg);
4647}
4648
4649/*
4650 * Requeue a task on a given node and accurately track the number of NUMA
4651 * tasks on the runqueues
4652 */
4653void sched_setnuma(struct task_struct *p, int nid)
4654{
4655 struct rq *rq;
4656 unsigned long flags;
4657 bool on_rq, running;
4658
4659 rq = task_rq_lock(p, &flags);
4660 on_rq = p->on_rq;
4661 running = task_current(rq, p);
4662
4663 if (on_rq)
4664 dequeue_task(rq, p, 0);
4665 if (running)
4666 p->sched_class->put_prev_task(rq, p);
4667
4668 p->numa_preferred_nid = nid;
4669
4670 if (running)
4671 p->sched_class->set_curr_task(rq);
4672 if (on_rq)
4673 enqueue_task(rq, p, 0);
4674 task_rq_unlock(rq, p, &flags);
4675}
4676#endif
4677
4678/*
4679 * migration_cpu_stop - this will be executed by a highprio stopper thread
4680 * and performs thread migration by bumping thread off CPU then
4681 * 'pushing' onto another runqueue.
4682 */
4683static int migration_cpu_stop(void *data)
4684{
4685 struct migration_arg *arg = data;
4686
4687 /*
4688 * The original target cpu might have gone down and we might
4689 * be on another cpu but it doesn't matter.
4690 */
4691 local_irq_disable();
4692 __migrate_task(arg->task, raw_smp_processor_id(), arg->dest_cpu);
4693 local_irq_enable();
4694 return 0;
4695}
4696
4697#ifdef CONFIG_HOTPLUG_CPU
4698
4699/*
4700 * Ensures that the idle task is using init_mm right before its cpu goes
4701 * offline.
4702 */
4703void idle_task_exit(void)
4704{
4705 struct mm_struct *mm = current->active_mm;
4706
4707 BUG_ON(cpu_online(smp_processor_id()));
4708
4709 if (mm != &init_mm) {
4710 switch_mm(mm, &init_mm, current);
4711 finish_arch_post_lock_switch();
4712 }
4713 mmdrop(mm);
4714}
4715
4716/*
4717 * Since this CPU is going 'away' for a while, fold any nr_active delta
4718 * we might have. Assumes we're called after migrate_tasks() so that the
4719 * nr_active count is stable.
4720 *
4721 * Also see the comment "Global load-average calculations".
4722 */
4723static void calc_load_migrate(struct rq *rq)
4724{
4725 long delta = calc_load_fold_active(rq);
4726 if (delta)
4727 atomic_long_add(delta, &calc_load_tasks);
4728}
4729
4730static void put_prev_task_fake(struct rq *rq, struct task_struct *prev)
4731{
4732}
4733
4734static const struct sched_class fake_sched_class = {
4735 .put_prev_task = put_prev_task_fake,
4736};
4737
4738static struct task_struct fake_task = {
4739 /*
4740 * Avoid pull_{rt,dl}_task()
4741 */
4742 .prio = MAX_PRIO + 1,
4743 .sched_class = &fake_sched_class,
4744};
4745
4746/*
4747 * Migrate all tasks from the rq, sleeping tasks will be migrated by
4748 * try_to_wake_up()->select_task_rq().
4749 *
4750 * Called with rq->lock held even though we'er in stop_machine() and
4751 * there's no concurrency possible, we hold the required locks anyway
4752 * because of lock validation efforts.
4753 */
4754static void migrate_tasks(unsigned int dead_cpu)
4755{
4756 struct rq *rq = cpu_rq(dead_cpu);
4757 struct task_struct *next, *stop = rq->stop;
4758 int dest_cpu;
4759
4760 /*
4761 * Fudge the rq selection such that the below task selection loop
4762 * doesn't get stuck on the currently eligible stop task.
4763 *
4764 * We're currently inside stop_machine() and the rq is either stuck
4765 * in the stop_machine_cpu_stop() loop, or we're executing this code,
4766 * either way we should never end up calling schedule() until we're
4767 * done here.
4768 */
4769 rq->stop = NULL;
4770
4771 /*
4772 * put_prev_task() and pick_next_task() sched
4773 * class method both need to have an up-to-date
4774 * value of rq->clock[_task]
4775 */
4776 update_rq_clock(rq);
4777
4778 for ( ; ; ) {
4779 /*
4780 * There's this thread running, bail when that's the only
4781 * remaining thread.
4782 */
4783 if (rq->nr_running == 1)
4784 break;
4785
4786 next = pick_next_task(rq, &fake_task);
4787 BUG_ON(!next);
4788 next->sched_class->put_prev_task(rq, next);
4789
4790 /* Find suitable destination for @next, with force if needed. */
4791 dest_cpu = select_fallback_rq(dead_cpu, next);
4792 raw_spin_unlock(&rq->lock);
4793
4794 __migrate_task(next, dead_cpu, dest_cpu);
4795
4796 raw_spin_lock(&rq->lock);
4797 }
4798
4799 rq->stop = stop;
4800}
4801
4802#endif /* CONFIG_HOTPLUG_CPU */
4803
4804#if defined(CONFIG_SCHED_DEBUG) && defined(CONFIG_SYSCTL)
4805
4806static struct ctl_table sd_ctl_dir[] = {
4807 {
4808 .procname = "sched_domain",
4809 .mode = 0555,
4810 },
4811 {}
4812};
4813
4814static struct ctl_table sd_ctl_root[] = {
4815 {
4816 .procname = "kernel",
4817 .mode = 0555,
4818 .child = sd_ctl_dir,
4819 },
4820 {}
4821};
4822
4823static struct ctl_table *sd_alloc_ctl_entry(int n)
4824{
4825 struct ctl_table *entry =
4826 kcalloc(n, sizeof(struct ctl_table), GFP_KERNEL);
4827
4828 return entry;
4829}
4830
4831static void sd_free_ctl_entry(struct ctl_table **tablep)
4832{
4833 struct ctl_table *entry;
4834
4835 /*
4836 * In the intermediate directories, both the child directory and
4837 * procname are dynamically allocated and could fail but the mode
4838 * will always be set. In the lowest directory the names are
4839 * static strings and all have proc handlers.
4840 */
4841 for (entry = *tablep; entry->mode; entry++) {
4842 if (entry->child)
4843 sd_free_ctl_entry(&entry->child);
4844 if (entry->proc_handler == NULL)
4845 kfree(entry->procname);
4846 }
4847
4848 kfree(*tablep);
4849 *tablep = NULL;
4850}
4851
4852static int min_load_idx = 0;
4853static int max_load_idx = CPU_LOAD_IDX_MAX-1;
4854
4855static void
4856set_table_entry(struct ctl_table *entry,
4857 const char *procname, void *data, int maxlen,
4858 umode_t mode, proc_handler *proc_handler,
4859 bool load_idx)
4860{
4861 entry->procname = procname;
4862 entry->data = data;
4863 entry->maxlen = maxlen;
4864 entry->mode = mode;
4865 entry->proc_handler = proc_handler;
4866
4867 if (load_idx) {
4868 entry->extra1 = &min_load_idx;
4869 entry->extra2 = &max_load_idx;
4870 }
4871}
4872
4873static struct ctl_table *
4874sd_alloc_ctl_domain_table(struct sched_domain *sd)
4875{
4876 struct ctl_table *table = sd_alloc_ctl_entry(14);
4877
4878 if (table == NULL)
4879 return NULL;
4880
4881 set_table_entry(&table[0], "min_interval", &sd->min_interval,
4882 sizeof(long), 0644, proc_doulongvec_minmax, false);
4883 set_table_entry(&table[1], "max_interval", &sd->max_interval,
4884 sizeof(long), 0644, proc_doulongvec_minmax, false);
4885 set_table_entry(&table[2], "busy_idx", &sd->busy_idx,
4886 sizeof(int), 0644, proc_dointvec_minmax, true);
4887 set_table_entry(&table[3], "idle_idx", &sd->idle_idx,
4888 sizeof(int), 0644, proc_dointvec_minmax, true);
4889 set_table_entry(&table[4], "newidle_idx", &sd->newidle_idx,
4890 sizeof(int), 0644, proc_dointvec_minmax, true);
4891 set_table_entry(&table[5], "wake_idx", &sd->wake_idx,
4892 sizeof(int), 0644, proc_dointvec_minmax, true);
4893 set_table_entry(&table[6], "forkexec_idx", &sd->forkexec_idx,
4894 sizeof(int), 0644, proc_dointvec_minmax, true);
4895 set_table_entry(&table[7], "busy_factor", &sd->busy_factor,
4896 sizeof(int), 0644, proc_dointvec_minmax, false);
4897 set_table_entry(&table[8], "imbalance_pct", &sd->imbalance_pct,
4898 sizeof(int), 0644, proc_dointvec_minmax, false);
4899 set_table_entry(&table[9], "cache_nice_tries",
4900 &sd->cache_nice_tries,
4901 sizeof(int), 0644, proc_dointvec_minmax, false);
4902 set_table_entry(&table[10], "flags", &sd->flags,
4903 sizeof(int), 0644, proc_dointvec_minmax, false);
4904 set_table_entry(&table[11], "max_newidle_lb_cost",
4905 &sd->max_newidle_lb_cost,
4906 sizeof(long), 0644, proc_doulongvec_minmax, false);
4907 set_table_entry(&table[12], "name", sd->name,
4908 CORENAME_MAX_SIZE, 0444, proc_dostring, false);
4909 /* &table[13] is terminator */
4910
4911 return table;
4912}
4913
4914static struct ctl_table *sd_alloc_ctl_cpu_table(int cpu)
4915{
4916 struct ctl_table *entry, *table;
4917 struct sched_domain *sd;
4918 int domain_num = 0, i;
4919 char buf[32];
4920
4921 for_each_domain(cpu, sd)
4922 domain_num++;
4923 entry = table = sd_alloc_ctl_entry(domain_num + 1);
4924 if (table == NULL)
4925 return NULL;
4926
4927 i = 0;
4928 for_each_domain(cpu, sd) {
4929 snprintf(buf, 32, "domain%d", i);
4930 entry->procname = kstrdup(buf, GFP_KERNEL);
4931 entry->mode = 0555;
4932 entry->child = sd_alloc_ctl_domain_table(sd);
4933 entry++;
4934 i++;
4935 }
4936 return table;
4937}
4938
4939static struct ctl_table_header *sd_sysctl_header;
4940static void register_sched_domain_sysctl(void)
4941{
4942 int i, cpu_num = num_possible_cpus();
4943 struct ctl_table *entry = sd_alloc_ctl_entry(cpu_num + 1);
4944 char buf[32];
4945
4946 WARN_ON(sd_ctl_dir[0].child);
4947 sd_ctl_dir[0].child = entry;
4948
4949 if (entry == NULL)
4950 return;
4951
4952 for_each_possible_cpu(i) {
4953 snprintf(buf, 32, "cpu%d", i);
4954 entry->procname = kstrdup(buf, GFP_KERNEL);
4955 entry->mode = 0555;
4956 entry->child = sd_alloc_ctl_cpu_table(i);
4957 entry++;
4958 }
4959
4960 WARN_ON(sd_sysctl_header);
4961 sd_sysctl_header = register_sysctl_table(sd_ctl_root);
4962}
4963
4964/* may be called multiple times per register */
4965static void unregister_sched_domain_sysctl(void)
4966{
4967 if (sd_sysctl_header)
4968 unregister_sysctl_table(sd_sysctl_header);
4969 sd_sysctl_header = NULL;
4970 if (sd_ctl_dir[0].child)
4971 sd_free_ctl_entry(&sd_ctl_dir[0].child);
4972}
4973#else
4974static void register_sched_domain_sysctl(void)
4975{
4976}
4977static void unregister_sched_domain_sysctl(void)
4978{
4979}
4980#endif
4981
4982static void set_rq_online(struct rq *rq)
4983{
4984 if (!rq->online) {
4985 const struct sched_class *class;
4986
4987 cpumask_set_cpu(rq->cpu, rq->rd->online);
4988 rq->online = 1;
4989
4990 for_each_class(class) {
4991 if (class->rq_online)
4992 class->rq_online(rq);
4993 }
4994 }
4995}
4996
4997static void set_rq_offline(struct rq *rq)
4998{
4999 if (rq->online) {
5000 const struct sched_class *class;
5001
5002 for_each_class(class) {
5003 if (class->rq_offline)
5004 class->rq_offline(rq);
5005 }
5006
5007 cpumask_clear_cpu(rq->cpu, rq->rd->online);
5008 rq->online = 0;
5009 }
5010}
5011
5012/*
5013 * migration_call - callback that gets triggered when a CPU is added.
5014 * Here we can start up the necessary migration thread for the new CPU.
5015 */
5016static int
5017migration_call(struct notifier_block *nfb, unsigned long action, void *hcpu)
5018{
5019 int cpu = (long)hcpu;
5020 unsigned long flags;
5021 struct rq *rq = cpu_rq(cpu);
5022
5023 switch (action & ~CPU_TASKS_FROZEN) {
5024
5025 case CPU_UP_PREPARE:
5026 rq->calc_load_update = calc_load_update;
5027 break;
5028
5029 case CPU_ONLINE:
5030 /* Update our root-domain */
5031 raw_spin_lock_irqsave(&rq->lock, flags);
5032 if (rq->rd) {
5033 BUG_ON(!cpumask_test_cpu(cpu, rq->rd->span));
5034
5035 set_rq_online(rq);
5036 }
5037 raw_spin_unlock_irqrestore(&rq->lock, flags);
5038 break;
5039
5040#ifdef CONFIG_HOTPLUG_CPU
5041 case CPU_DYING:
5042 sched_ttwu_pending();
5043 /* Update our root-domain */
5044 raw_spin_lock_irqsave(&rq->lock, flags);
5045 if (rq->rd) {
5046 BUG_ON(!cpumask_test_cpu(cpu, rq->rd->span));
5047 set_rq_offline(rq);
5048 }
5049 migrate_tasks(cpu);
5050 BUG_ON(rq->nr_running != 1); /* the migration thread */
5051 raw_spin_unlock_irqrestore(&rq->lock, flags);
5052 break;
5053
5054 case CPU_DEAD:
5055 calc_load_migrate(rq);
5056 break;
5057#endif
5058 }
5059
5060 update_max_interval();
5061
5062 return NOTIFY_OK;
5063}
5064
5065/*
5066 * Register at high priority so that task migration (migrate_all_tasks)
5067 * happens before everything else. This has to be lower priority than
5068 * the notifier in the perf_event subsystem, though.
5069 */
5070static struct notifier_block migration_notifier = {
5071 .notifier_call = migration_call,
5072 .priority = CPU_PRI_MIGRATION,
5073};
5074
5075static int sched_cpu_active(struct notifier_block *nfb,
5076 unsigned long action, void *hcpu)
5077{
5078 switch (action & ~CPU_TASKS_FROZEN) {
5079 case CPU_DOWN_FAILED:
5080 set_cpu_active((long)hcpu, true);
5081 return NOTIFY_OK;
5082 default:
5083 return NOTIFY_DONE;
5084 }
5085}
5086
5087static int sched_cpu_inactive(struct notifier_block *nfb,
5088 unsigned long action, void *hcpu)
5089{
5090 unsigned long flags;
5091 long cpu = (long)hcpu;
5092
5093 switch (action & ~CPU_TASKS_FROZEN) {
5094 case CPU_DOWN_PREPARE:
5095 set_cpu_active(cpu, false);
5096
5097 /* explicitly allow suspend */
5098 if (!(action & CPU_TASKS_FROZEN)) {
5099 struct dl_bw *dl_b = dl_bw_of(cpu);
5100 bool overflow;
5101 int cpus;
5102
5103 raw_spin_lock_irqsave(&dl_b->lock, flags);
5104 cpus = dl_bw_cpus(cpu);
5105 overflow = __dl_overflow(dl_b, cpus, 0, 0);
5106 raw_spin_unlock_irqrestore(&dl_b->lock, flags);
5107
5108 if (overflow)
5109 return notifier_from_errno(-EBUSY);
5110 }
5111 return NOTIFY_OK;
5112 }
5113
5114 return NOTIFY_DONE;
5115}
5116
5117static int __init migration_init(void)
5118{
5119 void *cpu = (void *)(long)smp_processor_id();
5120 int err;
5121
5122 /* Initialize migration for the boot CPU */
5123 err = migration_call(&migration_notifier, CPU_UP_PREPARE, cpu);
5124 BUG_ON(err == NOTIFY_BAD);
5125 migration_call(&migration_notifier, CPU_ONLINE, cpu);
5126 register_cpu_notifier(&migration_notifier);
5127
5128 /* Register cpu active notifiers */
5129 cpu_notifier(sched_cpu_active, CPU_PRI_SCHED_ACTIVE);
5130 cpu_notifier(sched_cpu_inactive, CPU_PRI_SCHED_INACTIVE);
5131
5132 return 0;
5133}
5134early_initcall(migration_init);
5135#endif
5136
5137#ifdef CONFIG_SMP
5138
5139static cpumask_var_t sched_domains_tmpmask; /* sched_domains_mutex */
5140
5141#ifdef CONFIG_SCHED_DEBUG
5142
5143static __read_mostly int sched_debug_enabled;
5144
5145static int __init sched_debug_setup(char *str)
5146{
5147 sched_debug_enabled = 1;
5148
5149 return 0;
5150}
5151early_param("sched_debug", sched_debug_setup);
5152
5153static inline bool sched_debug(void)
5154{
5155 return sched_debug_enabled;
5156}
5157
5158static int sched_domain_debug_one(struct sched_domain *sd, int cpu, int level,
5159 struct cpumask *groupmask)
5160{
5161 struct sched_group *group = sd->groups;
5162 char str[256];
5163
5164 cpulist_scnprintf(str, sizeof(str), sched_domain_span(sd));
5165 cpumask_clear(groupmask);
5166
5167 printk(KERN_DEBUG "%*s domain %d: ", level, "", level);
5168
5169 if (!(sd->flags & SD_LOAD_BALANCE)) {
5170 printk("does not load-balance\n");
5171 if (sd->parent)
5172 printk(KERN_ERR "ERROR: !SD_LOAD_BALANCE domain"
5173 " has parent");
5174 return -1;
5175 }
5176
5177 printk(KERN_CONT "span %s level %s\n", str, sd->name);
5178
5179 if (!cpumask_test_cpu(cpu, sched_domain_span(sd))) {
5180 printk(KERN_ERR "ERROR: domain->span does not contain "
5181 "CPU%d\n", cpu);
5182 }
5183 if (!cpumask_test_cpu(cpu, sched_group_cpus(group))) {
5184 printk(KERN_ERR "ERROR: domain->groups does not contain"
5185 " CPU%d\n", cpu);
5186 }
5187
5188 printk(KERN_DEBUG "%*s groups:", level + 1, "");
5189 do {
5190 if (!group) {
5191 printk("\n");
5192 printk(KERN_ERR "ERROR: group is NULL\n");
5193 break;
5194 }
5195
5196 /*
5197 * Even though we initialize ->power to something semi-sane,
5198 * we leave power_orig unset. This allows us to detect if
5199 * domain iteration is still funny without causing /0 traps.
5200 */
5201 if (!group->sgp->power_orig) {
5202 printk(KERN_CONT "\n");
5203 printk(KERN_ERR "ERROR: domain->cpu_power not "
5204 "set\n");
5205 break;
5206 }
5207
5208 if (!cpumask_weight(sched_group_cpus(group))) {
5209 printk(KERN_CONT "\n");
5210 printk(KERN_ERR "ERROR: empty group\n");
5211 break;
5212 }
5213
5214 if (!(sd->flags & SD_OVERLAP) &&
5215 cpumask_intersects(groupmask, sched_group_cpus(group))) {
5216 printk(KERN_CONT "\n");
5217 printk(KERN_ERR "ERROR: repeated CPUs\n");
5218 break;
5219 }
5220
5221 cpumask_or(groupmask, groupmask, sched_group_cpus(group));
5222
5223 cpulist_scnprintf(str, sizeof(str), sched_group_cpus(group));
5224
5225 printk(KERN_CONT " %s", str);
5226 if (group->sgp->power != SCHED_POWER_SCALE) {
5227 printk(KERN_CONT " (cpu_power = %d)",
5228 group->sgp->power);
5229 }
5230
5231 group = group->next;
5232 } while (group != sd->groups);
5233 printk(KERN_CONT "\n");
5234
5235 if (!cpumask_equal(sched_domain_span(sd), groupmask))
5236 printk(KERN_ERR "ERROR: groups don't span domain->span\n");
5237
5238 if (sd->parent &&
5239 !cpumask_subset(groupmask, sched_domain_span(sd->parent)))
5240 printk(KERN_ERR "ERROR: parent span is not a superset "
5241 "of domain->span\n");
5242 return 0;
5243}
5244
5245static void sched_domain_debug(struct sched_domain *sd, int cpu)
5246{
5247 int level = 0;
5248
5249 if (!sched_debug_enabled)
5250 return;
5251
5252 if (!sd) {
5253 printk(KERN_DEBUG "CPU%d attaching NULL sched-domain.\n", cpu);
5254 return;
5255 }
5256
5257 printk(KERN_DEBUG "CPU%d attaching sched-domain:\n", cpu);
5258
5259 for (;;) {
5260 if (sched_domain_debug_one(sd, cpu, level, sched_domains_tmpmask))
5261 break;
5262 level++;
5263 sd = sd->parent;
5264 if (!sd)
5265 break;
5266 }
5267}
5268#else /* !CONFIG_SCHED_DEBUG */
5269# define sched_domain_debug(sd, cpu) do { } while (0)
5270static inline bool sched_debug(void)
5271{
5272 return false;
5273}
5274#endif /* CONFIG_SCHED_DEBUG */
5275
5276static int sd_degenerate(struct sched_domain *sd)
5277{
5278 if (cpumask_weight(sched_domain_span(sd)) == 1)
5279 return 1;
5280
5281 /* Following flags need at least 2 groups */
5282 if (sd->flags & (SD_LOAD_BALANCE |
5283 SD_BALANCE_NEWIDLE |
5284 SD_BALANCE_FORK |
5285 SD_BALANCE_EXEC |
5286 SD_SHARE_CPUPOWER |
5287 SD_SHARE_PKG_RESOURCES)) {
5288 if (sd->groups != sd->groups->next)
5289 return 0;
5290 }
5291
5292 /* Following flags don't use groups */
5293 if (sd->flags & (SD_WAKE_AFFINE))
5294 return 0;
5295
5296 return 1;
5297}
5298
5299static int
5300sd_parent_degenerate(struct sched_domain *sd, struct sched_domain *parent)
5301{
5302 unsigned long cflags = sd->flags, pflags = parent->flags;
5303
5304 if (sd_degenerate(parent))
5305 return 1;
5306
5307 if (!cpumask_equal(sched_domain_span(sd), sched_domain_span(parent)))
5308 return 0;
5309
5310 /* Flags needing groups don't count if only 1 group in parent */
5311 if (parent->groups == parent->groups->next) {
5312 pflags &= ~(SD_LOAD_BALANCE |
5313 SD_BALANCE_NEWIDLE |
5314 SD_BALANCE_FORK |
5315 SD_BALANCE_EXEC |
5316 SD_SHARE_CPUPOWER |
5317 SD_SHARE_PKG_RESOURCES |
5318 SD_PREFER_SIBLING);
5319 if (nr_node_ids == 1)
5320 pflags &= ~SD_SERIALIZE;
5321 }
5322 if (~cflags & pflags)
5323 return 0;
5324
5325 return 1;
5326}
5327
5328static void free_rootdomain(struct rcu_head *rcu)
5329{
5330 struct root_domain *rd = container_of(rcu, struct root_domain, rcu);
5331
5332 cpupri_cleanup(&rd->cpupri);
5333 cpudl_cleanup(&rd->cpudl);
5334 free_cpumask_var(rd->dlo_mask);
5335 free_cpumask_var(rd->rto_mask);
5336 free_cpumask_var(rd->online);
5337 free_cpumask_var(rd->span);
5338 kfree(rd);
5339}
5340
5341static void rq_attach_root(struct rq *rq, struct root_domain *rd)
5342{
5343 struct root_domain *old_rd = NULL;
5344 unsigned long flags;
5345
5346 raw_spin_lock_irqsave(&rq->lock, flags);
5347
5348 if (rq->rd) {
5349 old_rd = rq->rd;
5350
5351 if (cpumask_test_cpu(rq->cpu, old_rd->online))
5352 set_rq_offline(rq);
5353
5354 cpumask_clear_cpu(rq->cpu, old_rd->span);
5355
5356 /*
5357 * If we dont want to free the old_rd yet then
5358 * set old_rd to NULL to skip the freeing later
5359 * in this function:
5360 */
5361 if (!atomic_dec_and_test(&old_rd->refcount))
5362 old_rd = NULL;
5363 }
5364
5365 atomic_inc(&rd->refcount);
5366 rq->rd = rd;
5367
5368 cpumask_set_cpu(rq->cpu, rd->span);
5369 if (cpumask_test_cpu(rq->cpu, cpu_active_mask))
5370 set_rq_online(rq);
5371
5372 raw_spin_unlock_irqrestore(&rq->lock, flags);
5373
5374 if (old_rd)
5375 call_rcu_sched(&old_rd->rcu, free_rootdomain);
5376}
5377
5378static int init_rootdomain(struct root_domain *rd)
5379{
5380 memset(rd, 0, sizeof(*rd));
5381
5382 if (!alloc_cpumask_var(&rd->span, GFP_KERNEL))
5383 goto out;
5384 if (!alloc_cpumask_var(&rd->online, GFP_KERNEL))
5385 goto free_span;
5386 if (!alloc_cpumask_var(&rd->dlo_mask, GFP_KERNEL))
5387 goto free_online;
5388 if (!alloc_cpumask_var(&rd->rto_mask, GFP_KERNEL))
5389 goto free_dlo_mask;
5390
5391 init_dl_bw(&rd->dl_bw);
5392 if (cpudl_init(&rd->cpudl) != 0)
5393 goto free_dlo_mask;
5394
5395 if (cpupri_init(&rd->cpupri) != 0)
5396 goto free_rto_mask;
5397 return 0;
5398
5399free_rto_mask:
5400 free_cpumask_var(rd->rto_mask);
5401free_dlo_mask:
5402 free_cpumask_var(rd->dlo_mask);
5403free_online:
5404 free_cpumask_var(rd->online);
5405free_span:
5406 free_cpumask_var(rd->span);
5407out:
5408 return -ENOMEM;
5409}
5410
5411/*
5412 * By default the system creates a single root-domain with all cpus as
5413 * members (mimicking the global state we have today).
5414 */
5415struct root_domain def_root_domain;
5416
5417static void init_defrootdomain(void)
5418{
5419 init_rootdomain(&def_root_domain);
5420
5421 atomic_set(&def_root_domain.refcount, 1);
5422}
5423
5424static struct root_domain *alloc_rootdomain(void)
5425{
5426 struct root_domain *rd;
5427
5428 rd = kmalloc(sizeof(*rd), GFP_KERNEL);
5429 if (!rd)
5430 return NULL;
5431
5432 if (init_rootdomain(rd) != 0) {
5433 kfree(rd);
5434 return NULL;
5435 }
5436
5437 return rd;
5438}
5439
5440static void free_sched_groups(struct sched_group *sg, int free_sgp)
5441{
5442 struct sched_group *tmp, *first;
5443
5444 if (!sg)
5445 return;
5446
5447 first = sg;
5448 do {
5449 tmp = sg->next;
5450
5451 if (free_sgp && atomic_dec_and_test(&sg->sgp->ref))
5452 kfree(sg->sgp);
5453
5454 kfree(sg);
5455 sg = tmp;
5456 } while (sg != first);
5457}
5458
5459static void free_sched_domain(struct rcu_head *rcu)
5460{
5461 struct sched_domain *sd = container_of(rcu, struct sched_domain, rcu);
5462
5463 /*
5464 * If its an overlapping domain it has private groups, iterate and
5465 * nuke them all.
5466 */
5467 if (sd->flags & SD_OVERLAP) {
5468 free_sched_groups(sd->groups, 1);
5469 } else if (atomic_dec_and_test(&sd->groups->ref)) {
5470 kfree(sd->groups->sgp);
5471 kfree(sd->groups);
5472 }
5473 kfree(sd);
5474}
5475
5476static void destroy_sched_domain(struct sched_domain *sd, int cpu)
5477{
5478 call_rcu(&sd->rcu, free_sched_domain);
5479}
5480
5481static void destroy_sched_domains(struct sched_domain *sd, int cpu)
5482{
5483 for (; sd; sd = sd->parent)
5484 destroy_sched_domain(sd, cpu);
5485}
5486
5487/*
5488 * Keep a special pointer to the highest sched_domain that has
5489 * SD_SHARE_PKG_RESOURCE set (Last Level Cache Domain) for this
5490 * allows us to avoid some pointer chasing select_idle_sibling().
5491 *
5492 * Also keep a unique ID per domain (we use the first cpu number in
5493 * the cpumask of the domain), this allows us to quickly tell if
5494 * two cpus are in the same cache domain, see cpus_share_cache().
5495 */
5496DEFINE_PER_CPU(struct sched_domain *, sd_llc);
5497DEFINE_PER_CPU(int, sd_llc_size);
5498DEFINE_PER_CPU(int, sd_llc_id);
5499DEFINE_PER_CPU(struct sched_domain *, sd_numa);
5500DEFINE_PER_CPU(struct sched_domain *, sd_busy);
5501DEFINE_PER_CPU(struct sched_domain *, sd_asym);
5502
5503static void update_top_cache_domain(int cpu)
5504{
5505 struct sched_domain *sd;
5506 struct sched_domain *busy_sd = NULL;
5507 int id = cpu;
5508 int size = 1;
5509
5510 sd = highest_flag_domain(cpu, SD_SHARE_PKG_RESOURCES);
5511 if (sd) {
5512 id = cpumask_first(sched_domain_span(sd));
5513 size = cpumask_weight(sched_domain_span(sd));
5514 busy_sd = sd->parent; /* sd_busy */
5515 }
5516 rcu_assign_pointer(per_cpu(sd_busy, cpu), busy_sd);
5517
5518 rcu_assign_pointer(per_cpu(sd_llc, cpu), sd);
5519 per_cpu(sd_llc_size, cpu) = size;
5520 per_cpu(sd_llc_id, cpu) = id;
5521
5522 sd = lowest_flag_domain(cpu, SD_NUMA);
5523 rcu_assign_pointer(per_cpu(sd_numa, cpu), sd);
5524
5525 sd = highest_flag_domain(cpu, SD_ASYM_PACKING);
5526 rcu_assign_pointer(per_cpu(sd_asym, cpu), sd);
5527}
5528
5529/*
5530 * Attach the domain 'sd' to 'cpu' as its base domain. Callers must
5531 * hold the hotplug lock.
5532 */
5533static void
5534cpu_attach_domain(struct sched_domain *sd, struct root_domain *rd, int cpu)
5535{
5536 struct rq *rq = cpu_rq(cpu);
5537 struct sched_domain *tmp;
5538
5539 /* Remove the sched domains which do not contribute to scheduling. */
5540 for (tmp = sd; tmp; ) {
5541 struct sched_domain *parent = tmp->parent;
5542 if (!parent)
5543 break;
5544
5545 if (sd_parent_degenerate(tmp, parent)) {
5546 tmp->parent = parent->parent;
5547 if (parent->parent)
5548 parent->parent->child = tmp;
5549 /*
5550 * Transfer SD_PREFER_SIBLING down in case of a
5551 * degenerate parent; the spans match for this
5552 * so the property transfers.
5553 */
5554 if (parent->flags & SD_PREFER_SIBLING)
5555 tmp->flags |= SD_PREFER_SIBLING;
5556 destroy_sched_domain(parent, cpu);
5557 } else
5558 tmp = tmp->parent;
5559 }
5560
5561 if (sd && sd_degenerate(sd)) {
5562 tmp = sd;
5563 sd = sd->parent;
5564 destroy_sched_domain(tmp, cpu);
5565 if (sd)
5566 sd->child = NULL;
5567 }
5568
5569 sched_domain_debug(sd, cpu);
5570
5571 rq_attach_root(rq, rd);
5572 tmp = rq->sd;
5573 rcu_assign_pointer(rq->sd, sd);
5574 destroy_sched_domains(tmp, cpu);
5575
5576 update_top_cache_domain(cpu);
5577}
5578
5579/* cpus with isolated domains */
5580static cpumask_var_t cpu_isolated_map;
5581
5582/* Setup the mask of cpus configured for isolated domains */
5583static int __init isolated_cpu_setup(char *str)
5584{
5585 alloc_bootmem_cpumask_var(&cpu_isolated_map);
5586 cpulist_parse(str, cpu_isolated_map);
5587 return 1;
5588}
5589
5590__setup("isolcpus=", isolated_cpu_setup);
5591
5592static const struct cpumask *cpu_cpu_mask(int cpu)
5593{
5594 return cpumask_of_node(cpu_to_node(cpu));
5595}
5596
5597struct sd_data {
5598 struct sched_domain **__percpu sd;
5599 struct sched_group **__percpu sg;
5600 struct sched_group_power **__percpu sgp;
5601};
5602
5603struct s_data {
5604 struct sched_domain ** __percpu sd;
5605 struct root_domain *rd;
5606};
5607
5608enum s_alloc {
5609 sa_rootdomain,
5610 sa_sd,
5611 sa_sd_storage,
5612 sa_none,
5613};
5614
5615struct sched_domain_topology_level;
5616
5617typedef struct sched_domain *(*sched_domain_init_f)(struct sched_domain_topology_level *tl, int cpu);
5618typedef const struct cpumask *(*sched_domain_mask_f)(int cpu);
5619
5620#define SDTL_OVERLAP 0x01
5621
5622struct sched_domain_topology_level {
5623 sched_domain_init_f init;
5624 sched_domain_mask_f mask;
5625 int flags;
5626 int numa_level;
5627 struct sd_data data;
5628};
5629
5630/*
5631 * Build an iteration mask that can exclude certain CPUs from the upwards
5632 * domain traversal.
5633 *
5634 * Asymmetric node setups can result in situations where the domain tree is of
5635 * unequal depth, make sure to skip domains that already cover the entire
5636 * range.
5637 *
5638 * In that case build_sched_domains() will have terminated the iteration early
5639 * and our sibling sd spans will be empty. Domains should always include the
5640 * cpu they're built on, so check that.
5641 *
5642 */
5643static void build_group_mask(struct sched_domain *sd, struct sched_group *sg)
5644{
5645 const struct cpumask *span = sched_domain_span(sd);
5646 struct sd_data *sdd = sd->private;
5647 struct sched_domain *sibling;
5648 int i;
5649
5650 for_each_cpu(i, span) {
5651 sibling = *per_cpu_ptr(sdd->sd, i);
5652 if (!cpumask_test_cpu(i, sched_domain_span(sibling)))
5653 continue;
5654
5655 cpumask_set_cpu(i, sched_group_mask(sg));
5656 }
5657}
5658
5659/*
5660 * Return the canonical balance cpu for this group, this is the first cpu
5661 * of this group that's also in the iteration mask.
5662 */
5663int group_balance_cpu(struct sched_group *sg)
5664{
5665 return cpumask_first_and(sched_group_cpus(sg), sched_group_mask(sg));
5666}
5667
5668static int
5669build_overlap_sched_groups(struct sched_domain *sd, int cpu)
5670{
5671 struct sched_group *first = NULL, *last = NULL, *groups = NULL, *sg;
5672 const struct cpumask *span = sched_domain_span(sd);
5673 struct cpumask *covered = sched_domains_tmpmask;
5674 struct sd_data *sdd = sd->private;
5675 struct sched_domain *child;
5676 int i;
5677
5678 cpumask_clear(covered);
5679
5680 for_each_cpu(i, span) {
5681 struct cpumask *sg_span;
5682
5683 if (cpumask_test_cpu(i, covered))
5684 continue;
5685
5686 child = *per_cpu_ptr(sdd->sd, i);
5687
5688 /* See the comment near build_group_mask(). */
5689 if (!cpumask_test_cpu(i, sched_domain_span(child)))
5690 continue;
5691
5692 sg = kzalloc_node(sizeof(struct sched_group) + cpumask_size(),
5693 GFP_KERNEL, cpu_to_node(cpu));
5694
5695 if (!sg)
5696 goto fail;
5697
5698 sg_span = sched_group_cpus(sg);
5699 if (child->child) {
5700 child = child->child;
5701 cpumask_copy(sg_span, sched_domain_span(child));
5702 } else
5703 cpumask_set_cpu(i, sg_span);
5704
5705 cpumask_or(covered, covered, sg_span);
5706
5707 sg->sgp = *per_cpu_ptr(sdd->sgp, i);
5708 if (atomic_inc_return(&sg->sgp->ref) == 1)
5709 build_group_mask(sd, sg);
5710
5711 /*
5712 * Initialize sgp->power such that even if we mess up the
5713 * domains and no possible iteration will get us here, we won't
5714 * die on a /0 trap.
5715 */
5716 sg->sgp->power = SCHED_POWER_SCALE * cpumask_weight(sg_span);
5717 sg->sgp->power_orig = sg->sgp->power;
5718
5719 /*
5720 * Make sure the first group of this domain contains the
5721 * canonical balance cpu. Otherwise the sched_domain iteration
5722 * breaks. See update_sg_lb_stats().
5723 */
5724 if ((!groups && cpumask_test_cpu(cpu, sg_span)) ||
5725 group_balance_cpu(sg) == cpu)
5726 groups = sg;
5727
5728 if (!first)
5729 first = sg;
5730 if (last)
5731 last->next = sg;
5732 last = sg;
5733 last->next = first;
5734 }
5735 sd->groups = groups;
5736
5737 return 0;
5738
5739fail:
5740 free_sched_groups(first, 0);
5741
5742 return -ENOMEM;
5743}
5744
5745static int get_group(int cpu, struct sd_data *sdd, struct sched_group **sg)
5746{
5747 struct sched_domain *sd = *per_cpu_ptr(sdd->sd, cpu);
5748 struct sched_domain *child = sd->child;
5749
5750 if (child)
5751 cpu = cpumask_first(sched_domain_span(child));
5752
5753 if (sg) {
5754 *sg = *per_cpu_ptr(sdd->sg, cpu);
5755 (*sg)->sgp = *per_cpu_ptr(sdd->sgp, cpu);
5756 atomic_set(&(*sg)->sgp->ref, 1); /* for claim_allocations */
5757 }
5758
5759 return cpu;
5760}
5761
5762/*
5763 * build_sched_groups will build a circular linked list of the groups
5764 * covered by the given span, and will set each group's ->cpumask correctly,
5765 * and ->cpu_power to 0.
5766 *
5767 * Assumes the sched_domain tree is fully constructed
5768 */
5769static int
5770build_sched_groups(struct sched_domain *sd, int cpu)
5771{
5772 struct sched_group *first = NULL, *last = NULL;
5773 struct sd_data *sdd = sd->private;
5774 const struct cpumask *span = sched_domain_span(sd);
5775 struct cpumask *covered;
5776 int i;
5777
5778 get_group(cpu, sdd, &sd->groups);
5779 atomic_inc(&sd->groups->ref);
5780
5781 if (cpu != cpumask_first(span))
5782 return 0;
5783
5784 lockdep_assert_held(&sched_domains_mutex);
5785 covered = sched_domains_tmpmask;
5786
5787 cpumask_clear(covered);
5788
5789 for_each_cpu(i, span) {
5790 struct sched_group *sg;
5791 int group, j;
5792
5793 if (cpumask_test_cpu(i, covered))
5794 continue;
5795
5796 group = get_group(i, sdd, &sg);
5797 cpumask_clear(sched_group_cpus(sg));
5798 sg->sgp->power = 0;
5799 cpumask_setall(sched_group_mask(sg));
5800
5801 for_each_cpu(j, span) {
5802 if (get_group(j, sdd, NULL) != group)
5803 continue;
5804
5805 cpumask_set_cpu(j, covered);
5806 cpumask_set_cpu(j, sched_group_cpus(sg));
5807 }
5808
5809 if (!first)
5810 first = sg;
5811 if (last)
5812 last->next = sg;
5813 last = sg;
5814 }
5815 last->next = first;
5816
5817 return 0;
5818}
5819
5820/*
5821 * Initialize sched groups cpu_power.
5822 *
5823 * cpu_power indicates the capacity of sched group, which is used while
5824 * distributing the load between different sched groups in a sched domain.
5825 * Typically cpu_power for all the groups in a sched domain will be same unless
5826 * there are asymmetries in the topology. If there are asymmetries, group
5827 * having more cpu_power will pickup more load compared to the group having
5828 * less cpu_power.
5829 */
5830static void init_sched_groups_power(int cpu, struct sched_domain *sd)
5831{
5832 struct sched_group *sg = sd->groups;
5833
5834 WARN_ON(!sg);
5835
5836 do {
5837 sg->group_weight = cpumask_weight(sched_group_cpus(sg));
5838 sg = sg->next;
5839 } while (sg != sd->groups);
5840
5841 if (cpu != group_balance_cpu(sg))
5842 return;
5843
5844 update_group_power(sd, cpu);
5845 atomic_set(&sg->sgp->nr_busy_cpus, sg->group_weight);
5846}
5847
5848int __weak arch_sd_sibling_asym_packing(void)
5849{
5850 return 0*SD_ASYM_PACKING;
5851}
5852
5853/*
5854 * Initializers for schedule domains
5855 * Non-inlined to reduce accumulated stack pressure in build_sched_domains()
5856 */
5857
5858#ifdef CONFIG_SCHED_DEBUG
5859# define SD_INIT_NAME(sd, type) sd->name = #type
5860#else
5861# define SD_INIT_NAME(sd, type) do { } while (0)
5862#endif
5863
5864#define SD_INIT_FUNC(type) \
5865static noinline struct sched_domain * \
5866sd_init_##type(struct sched_domain_topology_level *tl, int cpu) \
5867{ \
5868 struct sched_domain *sd = *per_cpu_ptr(tl->data.sd, cpu); \
5869 *sd = SD_##type##_INIT; \
5870 SD_INIT_NAME(sd, type); \
5871 sd->private = &tl->data; \
5872 return sd; \
5873}
5874
5875SD_INIT_FUNC(CPU)
5876#ifdef CONFIG_SCHED_SMT
5877 SD_INIT_FUNC(SIBLING)
5878#endif
5879#ifdef CONFIG_SCHED_MC
5880 SD_INIT_FUNC(MC)
5881#endif
5882#ifdef CONFIG_SCHED_BOOK
5883 SD_INIT_FUNC(BOOK)
5884#endif
5885
5886static int default_relax_domain_level = -1;
5887int sched_domain_level_max;
5888
5889static int __init setup_relax_domain_level(char *str)
5890{
5891 if (kstrtoint(str, 0, &default_relax_domain_level))
5892 pr_warn("Unable to set relax_domain_level\n");
5893
5894 return 1;
5895}
5896__setup("relax_domain_level=", setup_relax_domain_level);
5897
5898static void set_domain_attribute(struct sched_domain *sd,
5899 struct sched_domain_attr *attr)
5900{
5901 int request;
5902
5903 if (!attr || attr->relax_domain_level < 0) {
5904 if (default_relax_domain_level < 0)
5905 return;
5906 else
5907 request = default_relax_domain_level;
5908 } else
5909 request = attr->relax_domain_level;
5910 if (request < sd->level) {
5911 /* turn off idle balance on this domain */
5912 sd->flags &= ~(SD_BALANCE_WAKE|SD_BALANCE_NEWIDLE);
5913 } else {
5914 /* turn on idle balance on this domain */
5915 sd->flags |= (SD_BALANCE_WAKE|SD_BALANCE_NEWIDLE);
5916 }
5917}
5918
5919static void __sdt_free(const struct cpumask *cpu_map);
5920static int __sdt_alloc(const struct cpumask *cpu_map);
5921
5922static void __free_domain_allocs(struct s_data *d, enum s_alloc what,
5923 const struct cpumask *cpu_map)
5924{
5925 switch (what) {
5926 case sa_rootdomain:
5927 if (!atomic_read(&d->rd->refcount))
5928 free_rootdomain(&d->rd->rcu); /* fall through */
5929 case sa_sd:
5930 free_percpu(d->sd); /* fall through */
5931 case sa_sd_storage:
5932 __sdt_free(cpu_map); /* fall through */
5933 case sa_none:
5934 break;
5935 }
5936}
5937
5938static enum s_alloc __visit_domain_allocation_hell(struct s_data *d,
5939 const struct cpumask *cpu_map)
5940{
5941 memset(d, 0, sizeof(*d));
5942
5943 if (__sdt_alloc(cpu_map))
5944 return sa_sd_storage;
5945 d->sd = alloc_percpu(struct sched_domain *);
5946 if (!d->sd)
5947 return sa_sd_storage;
5948 d->rd = alloc_rootdomain();
5949 if (!d->rd)
5950 return sa_sd;
5951 return sa_rootdomain;
5952}
5953
5954/*
5955 * NULL the sd_data elements we've used to build the sched_domain and
5956 * sched_group structure so that the subsequent __free_domain_allocs()
5957 * will not free the data we're using.
5958 */
5959static void claim_allocations(int cpu, struct sched_domain *sd)
5960{
5961 struct sd_data *sdd = sd->private;
5962
5963 WARN_ON_ONCE(*per_cpu_ptr(sdd->sd, cpu) != sd);
5964 *per_cpu_ptr(sdd->sd, cpu) = NULL;
5965
5966 if (atomic_read(&(*per_cpu_ptr(sdd->sg, cpu))->ref))
5967 *per_cpu_ptr(sdd->sg, cpu) = NULL;
5968
5969 if (atomic_read(&(*per_cpu_ptr(sdd->sgp, cpu))->ref))
5970 *per_cpu_ptr(sdd->sgp, cpu) = NULL;
5971}
5972
5973#ifdef CONFIG_SCHED_SMT
5974static const struct cpumask *cpu_smt_mask(int cpu)
5975{
5976 return topology_thread_cpumask(cpu);
5977}
5978#endif
5979
5980/*
5981 * Topology list, bottom-up.
5982 */
5983static struct sched_domain_topology_level default_topology[] = {
5984#ifdef CONFIG_SCHED_SMT
5985 { sd_init_SIBLING, cpu_smt_mask, },
5986#endif
5987#ifdef CONFIG_SCHED_MC
5988 { sd_init_MC, cpu_coregroup_mask, },
5989#endif
5990#ifdef CONFIG_SCHED_BOOK
5991 { sd_init_BOOK, cpu_book_mask, },
5992#endif
5993 { sd_init_CPU, cpu_cpu_mask, },
5994 { NULL, },
5995};
5996
5997static struct sched_domain_topology_level *sched_domain_topology = default_topology;
5998
5999#define for_each_sd_topology(tl) \
6000 for (tl = sched_domain_topology; tl->init; tl++)
6001
6002#ifdef CONFIG_NUMA
6003
6004static int sched_domains_numa_levels;
6005static int *sched_domains_numa_distance;
6006static struct cpumask ***sched_domains_numa_masks;
6007static int sched_domains_curr_level;
6008
6009static inline int sd_local_flags(int level)
6010{
6011 if (sched_domains_numa_distance[level] > RECLAIM_DISTANCE)
6012 return 0;
6013
6014 return SD_BALANCE_EXEC | SD_BALANCE_FORK | SD_WAKE_AFFINE;
6015}
6016
6017static struct sched_domain *
6018sd_numa_init(struct sched_domain_topology_level *tl, int cpu)
6019{
6020 struct sched_domain *sd = *per_cpu_ptr(tl->data.sd, cpu);
6021 int level = tl->numa_level;
6022 int sd_weight = cpumask_weight(
6023 sched_domains_numa_masks[level][cpu_to_node(cpu)]);
6024
6025 *sd = (struct sched_domain){
6026 .min_interval = sd_weight,
6027 .max_interval = 2*sd_weight,
6028 .busy_factor = 32,
6029 .imbalance_pct = 125,
6030 .cache_nice_tries = 2,
6031 .busy_idx = 3,
6032 .idle_idx = 2,
6033 .newidle_idx = 0,
6034 .wake_idx = 0,
6035 .forkexec_idx = 0,
6036
6037 .flags = 1*SD_LOAD_BALANCE
6038 | 1*SD_BALANCE_NEWIDLE
6039 | 0*SD_BALANCE_EXEC
6040 | 0*SD_BALANCE_FORK
6041 | 0*SD_BALANCE_WAKE
6042 | 0*SD_WAKE_AFFINE
6043 | 0*SD_SHARE_CPUPOWER
6044 | 0*SD_SHARE_PKG_RESOURCES
6045 | 1*SD_SERIALIZE
6046 | 0*SD_PREFER_SIBLING
6047 | 1*SD_NUMA
6048 | sd_local_flags(level)
6049 ,
6050 .last_balance = jiffies,
6051 .balance_interval = sd_weight,
6052 .max_newidle_lb_cost = 0,
6053 .next_decay_max_lb_cost = jiffies,
6054 };
6055 SD_INIT_NAME(sd, NUMA);
6056 sd->private = &tl->data;
6057
6058 /*
6059 * Ugly hack to pass state to sd_numa_mask()...
6060 */
6061 sched_domains_curr_level = tl->numa_level;
6062
6063 return sd;
6064}
6065
6066static const struct cpumask *sd_numa_mask(int cpu)
6067{
6068 return sched_domains_numa_masks[sched_domains_curr_level][cpu_to_node(cpu)];
6069}
6070
6071static void sched_numa_warn(const char *str)
6072{
6073 static int done = false;
6074 int i,j;
6075
6076 if (done)
6077 return;
6078
6079 done = true;
6080
6081 printk(KERN_WARNING "ERROR: %s\n\n", str);
6082
6083 for (i = 0; i < nr_node_ids; i++) {
6084 printk(KERN_WARNING " ");
6085 for (j = 0; j < nr_node_ids; j++)
6086 printk(KERN_CONT "%02d ", node_distance(i,j));
6087 printk(KERN_CONT "\n");
6088 }
6089 printk(KERN_WARNING "\n");
6090}
6091
6092static bool find_numa_distance(int distance)
6093{
6094 int i;
6095
6096 if (distance == node_distance(0, 0))
6097 return true;
6098
6099 for (i = 0; i < sched_domains_numa_levels; i++) {
6100 if (sched_domains_numa_distance[i] == distance)
6101 return true;
6102 }
6103
6104 return false;
6105}
6106
6107static void sched_init_numa(void)
6108{
6109 int next_distance, curr_distance = node_distance(0, 0);
6110 struct sched_domain_topology_level *tl;
6111 int level = 0;
6112 int i, j, k;
6113
6114 sched_domains_numa_distance = kzalloc(sizeof(int) * nr_node_ids, GFP_KERNEL);
6115 if (!sched_domains_numa_distance)
6116 return;
6117
6118 /*
6119 * O(nr_nodes^2) deduplicating selection sort -- in order to find the
6120 * unique distances in the node_distance() table.
6121 *
6122 * Assumes node_distance(0,j) includes all distances in
6123 * node_distance(i,j) in order to avoid cubic time.
6124 */
6125 next_distance = curr_distance;
6126 for (i = 0; i < nr_node_ids; i++) {
6127 for (j = 0; j < nr_node_ids; j++) {
6128 for (k = 0; k < nr_node_ids; k++) {
6129 int distance = node_distance(i, k);
6130
6131 if (distance > curr_distance &&
6132 (distance < next_distance ||
6133 next_distance == curr_distance))
6134 next_distance = distance;
6135
6136 /*
6137 * While not a strong assumption it would be nice to know
6138 * about cases where if node A is connected to B, B is not
6139 * equally connected to A.
6140 */
6141 if (sched_debug() && node_distance(k, i) != distance)
6142 sched_numa_warn("Node-distance not symmetric");
6143
6144 if (sched_debug() && i && !find_numa_distance(distance))
6145 sched_numa_warn("Node-0 not representative");
6146 }
6147 if (next_distance != curr_distance) {
6148 sched_domains_numa_distance[level++] = next_distance;
6149 sched_domains_numa_levels = level;
6150 curr_distance = next_distance;
6151 } else break;
6152 }
6153
6154 /*
6155 * In case of sched_debug() we verify the above assumption.
6156 */
6157 if (!sched_debug())
6158 break;
6159 }
6160 /*
6161 * 'level' contains the number of unique distances, excluding the
6162 * identity distance node_distance(i,i).
6163 *
6164 * The sched_domains_numa_distance[] array includes the actual distance
6165 * numbers.
6166 */
6167
6168 /*
6169 * Here, we should temporarily reset sched_domains_numa_levels to 0.
6170 * If it fails to allocate memory for array sched_domains_numa_masks[][],
6171 * the array will contain less then 'level' members. This could be
6172 * dangerous when we use it to iterate array sched_domains_numa_masks[][]
6173 * in other functions.
6174 *
6175 * We reset it to 'level' at the end of this function.
6176 */
6177 sched_domains_numa_levels = 0;
6178
6179 sched_domains_numa_masks = kzalloc(sizeof(void *) * level, GFP_KERNEL);
6180 if (!sched_domains_numa_masks)
6181 return;
6182
6183 /*
6184 * Now for each level, construct a mask per node which contains all
6185 * cpus of nodes that are that many hops away from us.
6186 */
6187 for (i = 0; i < level; i++) {
6188 sched_domains_numa_masks[i] =
6189 kzalloc(nr_node_ids * sizeof(void *), GFP_KERNEL);
6190 if (!sched_domains_numa_masks[i])
6191 return;
6192
6193 for (j = 0; j < nr_node_ids; j++) {
6194 struct cpumask *mask = kzalloc(cpumask_size(), GFP_KERNEL);
6195 if (!mask)
6196 return;
6197
6198 sched_domains_numa_masks[i][j] = mask;
6199
6200 for (k = 0; k < nr_node_ids; k++) {
6201 if (node_distance(j, k) > sched_domains_numa_distance[i])
6202 continue;
6203
6204 cpumask_or(mask, mask, cpumask_of_node(k));
6205 }
6206 }
6207 }
6208
6209 tl = kzalloc((ARRAY_SIZE(default_topology) + level) *
6210 sizeof(struct sched_domain_topology_level), GFP_KERNEL);
6211 if (!tl)
6212 return;
6213
6214 /*
6215 * Copy the default topology bits..
6216 */
6217 for (i = 0; default_topology[i].init; i++)
6218 tl[i] = default_topology[i];
6219
6220 /*
6221 * .. and append 'j' levels of NUMA goodness.
6222 */
6223 for (j = 0; j < level; i++, j++) {
6224 tl[i] = (struct sched_domain_topology_level){
6225 .init = sd_numa_init,
6226 .mask = sd_numa_mask,
6227 .flags = SDTL_OVERLAP,
6228 .numa_level = j,
6229 };
6230 }
6231
6232 sched_domain_topology = tl;
6233
6234 sched_domains_numa_levels = level;
6235}
6236
6237static void sched_domains_numa_masks_set(int cpu)
6238{
6239 int i, j;
6240 int node = cpu_to_node(cpu);
6241
6242 for (i = 0; i < sched_domains_numa_levels; i++) {
6243 for (j = 0; j < nr_node_ids; j++) {
6244 if (node_distance(j, node) <= sched_domains_numa_distance[i])
6245 cpumask_set_cpu(cpu, sched_domains_numa_masks[i][j]);
6246 }
6247 }
6248}
6249
6250static void sched_domains_numa_masks_clear(int cpu)
6251{
6252 int i, j;
6253 for (i = 0; i < sched_domains_numa_levels; i++) {
6254 for (j = 0; j < nr_node_ids; j++)
6255 cpumask_clear_cpu(cpu, sched_domains_numa_masks[i][j]);
6256 }
6257}
6258
6259/*
6260 * Update sched_domains_numa_masks[level][node] array when new cpus
6261 * are onlined.
6262 */
6263static int sched_domains_numa_masks_update(struct notifier_block *nfb,
6264 unsigned long action,
6265 void *hcpu)
6266{
6267 int cpu = (long)hcpu;
6268
6269 switch (action & ~CPU_TASKS_FROZEN) {
6270 case CPU_ONLINE:
6271 sched_domains_numa_masks_set(cpu);
6272 break;
6273
6274 case CPU_DEAD:
6275 sched_domains_numa_masks_clear(cpu);
6276 break;
6277
6278 default:
6279 return NOTIFY_DONE;
6280 }
6281
6282 return NOTIFY_OK;
6283}
6284#else
6285static inline void sched_init_numa(void)
6286{
6287}
6288
6289static int sched_domains_numa_masks_update(struct notifier_block *nfb,
6290 unsigned long action,
6291 void *hcpu)
6292{
6293 return 0;
6294}
6295#endif /* CONFIG_NUMA */
6296
6297static int __sdt_alloc(const struct cpumask *cpu_map)
6298{
6299 struct sched_domain_topology_level *tl;
6300 int j;
6301
6302 for_each_sd_topology(tl) {
6303 struct sd_data *sdd = &tl->data;
6304
6305 sdd->sd = alloc_percpu(struct sched_domain *);
6306 if (!sdd->sd)
6307 return -ENOMEM;
6308
6309 sdd->sg = alloc_percpu(struct sched_group *);
6310 if (!sdd->sg)
6311 return -ENOMEM;
6312
6313 sdd->sgp = alloc_percpu(struct sched_group_power *);
6314 if (!sdd->sgp)
6315 return -ENOMEM;
6316
6317 for_each_cpu(j, cpu_map) {
6318 struct sched_domain *sd;
6319 struct sched_group *sg;
6320 struct sched_group_power *sgp;
6321
6322 sd = kzalloc_node(sizeof(struct sched_domain) + cpumask_size(),
6323 GFP_KERNEL, cpu_to_node(j));
6324 if (!sd)
6325 return -ENOMEM;
6326
6327 *per_cpu_ptr(sdd->sd, j) = sd;
6328
6329 sg = kzalloc_node(sizeof(struct sched_group) + cpumask_size(),
6330 GFP_KERNEL, cpu_to_node(j));
6331 if (!sg)
6332 return -ENOMEM;
6333
6334 sg->next = sg;
6335
6336 *per_cpu_ptr(sdd->sg, j) = sg;
6337
6338 sgp = kzalloc_node(sizeof(struct sched_group_power) + cpumask_size(),
6339 GFP_KERNEL, cpu_to_node(j));
6340 if (!sgp)
6341 return -ENOMEM;
6342
6343 *per_cpu_ptr(sdd->sgp, j) = sgp;
6344 }
6345 }
6346
6347 return 0;
6348}
6349
6350static void __sdt_free(const struct cpumask *cpu_map)
6351{
6352 struct sched_domain_topology_level *tl;
6353 int j;
6354
6355 for_each_sd_topology(tl) {
6356 struct sd_data *sdd = &tl->data;
6357
6358 for_each_cpu(j, cpu_map) {
6359 struct sched_domain *sd;
6360
6361 if (sdd->sd) {
6362 sd = *per_cpu_ptr(sdd->sd, j);
6363 if (sd && (sd->flags & SD_OVERLAP))
6364 free_sched_groups(sd->groups, 0);
6365 kfree(*per_cpu_ptr(sdd->sd, j));
6366 }
6367
6368 if (sdd->sg)
6369 kfree(*per_cpu_ptr(sdd->sg, j));
6370 if (sdd->sgp)
6371 kfree(*per_cpu_ptr(sdd->sgp, j));
6372 }
6373 free_percpu(sdd->sd);
6374 sdd->sd = NULL;
6375 free_percpu(sdd->sg);
6376 sdd->sg = NULL;
6377 free_percpu(sdd->sgp);
6378 sdd->sgp = NULL;
6379 }
6380}
6381
6382struct sched_domain *build_sched_domain(struct sched_domain_topology_level *tl,
6383 const struct cpumask *cpu_map, struct sched_domain_attr *attr,
6384 struct sched_domain *child, int cpu)
6385{
6386 struct sched_domain *sd = tl->init(tl, cpu);
6387 if (!sd)
6388 return child;
6389
6390 cpumask_and(sched_domain_span(sd), cpu_map, tl->mask(cpu));
6391 if (child) {
6392 sd->level = child->level + 1;
6393 sched_domain_level_max = max(sched_domain_level_max, sd->level);
6394 child->parent = sd;
6395 sd->child = child;
6396 }
6397 set_domain_attribute(sd, attr);
6398
6399 return sd;
6400}
6401
6402/*
6403 * Build sched domains for a given set of cpus and attach the sched domains
6404 * to the individual cpus
6405 */
6406static int build_sched_domains(const struct cpumask *cpu_map,
6407 struct sched_domain_attr *attr)
6408{
6409 enum s_alloc alloc_state;
6410 struct sched_domain *sd;
6411 struct s_data d;
6412 int i, ret = -ENOMEM;
6413
6414 alloc_state = __visit_domain_allocation_hell(&d, cpu_map);
6415 if (alloc_state != sa_rootdomain)
6416 goto error;
6417
6418 /* Set up domains for cpus specified by the cpu_map. */
6419 for_each_cpu(i, cpu_map) {
6420 struct sched_domain_topology_level *tl;
6421
6422 sd = NULL;
6423 for_each_sd_topology(tl) {
6424 sd = build_sched_domain(tl, cpu_map, attr, sd, i);
6425 if (tl == sched_domain_topology)
6426 *per_cpu_ptr(d.sd, i) = sd;
6427 if (tl->flags & SDTL_OVERLAP || sched_feat(FORCE_SD_OVERLAP))
6428 sd->flags |= SD_OVERLAP;
6429 if (cpumask_equal(cpu_map, sched_domain_span(sd)))
6430 break;
6431 }
6432 }
6433
6434 /* Build the groups for the domains */
6435 for_each_cpu(i, cpu_map) {
6436 for (sd = *per_cpu_ptr(d.sd, i); sd; sd = sd->parent) {
6437 sd->span_weight = cpumask_weight(sched_domain_span(sd));
6438 if (sd->flags & SD_OVERLAP) {
6439 if (build_overlap_sched_groups(sd, i))
6440 goto error;
6441 } else {
6442 if (build_sched_groups(sd, i))
6443 goto error;
6444 }
6445 }
6446 }
6447
6448 /* Calculate CPU power for physical packages and nodes */
6449 for (i = nr_cpumask_bits-1; i >= 0; i--) {
6450 if (!cpumask_test_cpu(i, cpu_map))
6451 continue;
6452
6453 for (sd = *per_cpu_ptr(d.sd, i); sd; sd = sd->parent) {
6454 claim_allocations(i, sd);
6455 init_sched_groups_power(i, sd);
6456 }
6457 }
6458
6459 /* Attach the domains */
6460 rcu_read_lock();
6461 for_each_cpu(i, cpu_map) {
6462 sd = *per_cpu_ptr(d.sd, i);
6463 cpu_attach_domain(sd, d.rd, i);
6464 }
6465 rcu_read_unlock();
6466
6467 ret = 0;
6468error:
6469 __free_domain_allocs(&d, alloc_state, cpu_map);
6470 return ret;
6471}
6472
6473static cpumask_var_t *doms_cur; /* current sched domains */
6474static int ndoms_cur; /* number of sched domains in 'doms_cur' */
6475static struct sched_domain_attr *dattr_cur;
6476 /* attribues of custom domains in 'doms_cur' */
6477
6478/*
6479 * Special case: If a kmalloc of a doms_cur partition (array of
6480 * cpumask) fails, then fallback to a single sched domain,
6481 * as determined by the single cpumask fallback_doms.
6482 */
6483static cpumask_var_t fallback_doms;
6484
6485/*
6486 * arch_update_cpu_topology lets virtualized architectures update the
6487 * cpu core maps. It is supposed to return 1 if the topology changed
6488 * or 0 if it stayed the same.
6489 */
6490int __weak arch_update_cpu_topology(void)
6491{
6492 return 0;
6493}
6494
6495cpumask_var_t *alloc_sched_domains(unsigned int ndoms)
6496{
6497 int i;
6498 cpumask_var_t *doms;
6499
6500 doms = kmalloc(sizeof(*doms) * ndoms, GFP_KERNEL);
6501 if (!doms)
6502 return NULL;
6503 for (i = 0; i < ndoms; i++) {
6504 if (!alloc_cpumask_var(&doms[i], GFP_KERNEL)) {
6505 free_sched_domains(doms, i);
6506 return NULL;
6507 }
6508 }
6509 return doms;
6510}
6511
6512void free_sched_domains(cpumask_var_t doms[], unsigned int ndoms)
6513{
6514 unsigned int i;
6515 for (i = 0; i < ndoms; i++)
6516 free_cpumask_var(doms[i]);
6517 kfree(doms);
6518}
6519
6520/*
6521 * Set up scheduler domains and groups. Callers must hold the hotplug lock.
6522 * For now this just excludes isolated cpus, but could be used to
6523 * exclude other special cases in the future.
6524 */
6525static int init_sched_domains(const struct cpumask *cpu_map)
6526{
6527 int err;
6528
6529 arch_update_cpu_topology();
6530 ndoms_cur = 1;
6531 doms_cur = alloc_sched_domains(ndoms_cur);
6532 if (!doms_cur)
6533 doms_cur = &fallback_doms;
6534 cpumask_andnot(doms_cur[0], cpu_map, cpu_isolated_map);
6535 err = build_sched_domains(doms_cur[0], NULL);
6536 register_sched_domain_sysctl();
6537
6538 return err;
6539}
6540
6541/*
6542 * Detach sched domains from a group of cpus specified in cpu_map
6543 * These cpus will now be attached to the NULL domain
6544 */
6545static void detach_destroy_domains(const struct cpumask *cpu_map)
6546{
6547 int i;
6548
6549 rcu_read_lock();
6550 for_each_cpu(i, cpu_map)
6551 cpu_attach_domain(NULL, &def_root_domain, i);
6552 rcu_read_unlock();
6553}
6554
6555/* handle null as "default" */
6556static int dattrs_equal(struct sched_domain_attr *cur, int idx_cur,
6557 struct sched_domain_attr *new, int idx_new)
6558{
6559 struct sched_domain_attr tmp;
6560
6561 /* fast path */
6562 if (!new && !cur)
6563 return 1;
6564
6565 tmp = SD_ATTR_INIT;
6566 return !memcmp(cur ? (cur + idx_cur) : &tmp,
6567 new ? (new + idx_new) : &tmp,
6568 sizeof(struct sched_domain_attr));
6569}
6570
6571/*
6572 * Partition sched domains as specified by the 'ndoms_new'
6573 * cpumasks in the array doms_new[] of cpumasks. This compares
6574 * doms_new[] to the current sched domain partitioning, doms_cur[].
6575 * It destroys each deleted domain and builds each new domain.
6576 *
6577 * 'doms_new' is an array of cpumask_var_t's of length 'ndoms_new'.
6578 * The masks don't intersect (don't overlap.) We should setup one
6579 * sched domain for each mask. CPUs not in any of the cpumasks will
6580 * not be load balanced. If the same cpumask appears both in the
6581 * current 'doms_cur' domains and in the new 'doms_new', we can leave
6582 * it as it is.
6583 *
6584 * The passed in 'doms_new' should be allocated using
6585 * alloc_sched_domains. This routine takes ownership of it and will
6586 * free_sched_domains it when done with it. If the caller failed the
6587 * alloc call, then it can pass in doms_new == NULL && ndoms_new == 1,
6588 * and partition_sched_domains() will fallback to the single partition
6589 * 'fallback_doms', it also forces the domains to be rebuilt.
6590 *
6591 * If doms_new == NULL it will be replaced with cpu_online_mask.
6592 * ndoms_new == 0 is a special case for destroying existing domains,
6593 * and it will not create the default domain.
6594 *
6595 * Call with hotplug lock held
6596 */
6597void partition_sched_domains(int ndoms_new, cpumask_var_t doms_new[],
6598 struct sched_domain_attr *dattr_new)
6599{
6600 int i, j, n;
6601 int new_topology;
6602
6603 mutex_lock(&sched_domains_mutex);
6604
6605 /* always unregister in case we don't destroy any domains */
6606 unregister_sched_domain_sysctl();
6607
6608 /* Let architecture update cpu core mappings. */
6609 new_topology = arch_update_cpu_topology();
6610
6611 n = doms_new ? ndoms_new : 0;
6612
6613 /* Destroy deleted domains */
6614 for (i = 0; i < ndoms_cur; i++) {
6615 for (j = 0; j < n && !new_topology; j++) {
6616 if (cpumask_equal(doms_cur[i], doms_new[j])
6617 && dattrs_equal(dattr_cur, i, dattr_new, j))
6618 goto match1;
6619 }
6620 /* no match - a current sched domain not in new doms_new[] */
6621 detach_destroy_domains(doms_cur[i]);
6622match1:
6623 ;
6624 }
6625
6626 n = ndoms_cur;
6627 if (doms_new == NULL) {
6628 n = 0;
6629 doms_new = &fallback_doms;
6630 cpumask_andnot(doms_new[0], cpu_active_mask, cpu_isolated_map);
6631 WARN_ON_ONCE(dattr_new);
6632 }
6633
6634 /* Build new domains */
6635 for (i = 0; i < ndoms_new; i++) {
6636 for (j = 0; j < n && !new_topology; j++) {
6637 if (cpumask_equal(doms_new[i], doms_cur[j])
6638 && dattrs_equal(dattr_new, i, dattr_cur, j))
6639 goto match2;
6640 }
6641 /* no match - add a new doms_new */
6642 build_sched_domains(doms_new[i], dattr_new ? dattr_new + i : NULL);
6643match2:
6644 ;
6645 }
6646
6647 /* Remember the new sched domains */
6648 if (doms_cur != &fallback_doms)
6649 free_sched_domains(doms_cur, ndoms_cur);
6650 kfree(dattr_cur); /* kfree(NULL) is safe */
6651 doms_cur = doms_new;
6652 dattr_cur = dattr_new;
6653 ndoms_cur = ndoms_new;
6654
6655 register_sched_domain_sysctl();
6656
6657 mutex_unlock(&sched_domains_mutex);
6658}
6659
6660static int num_cpus_frozen; /* used to mark begin/end of suspend/resume */
6661
6662/*
6663 * Update cpusets according to cpu_active mask. If cpusets are
6664 * disabled, cpuset_update_active_cpus() becomes a simple wrapper
6665 * around partition_sched_domains().
6666 *
6667 * If we come here as part of a suspend/resume, don't touch cpusets because we
6668 * want to restore it back to its original state upon resume anyway.
6669 */
6670static int cpuset_cpu_active(struct notifier_block *nfb, unsigned long action,
6671 void *hcpu)
6672{
6673 switch (action) {
6674 case CPU_ONLINE_FROZEN:
6675 case CPU_DOWN_FAILED_FROZEN:
6676
6677 /*
6678 * num_cpus_frozen tracks how many CPUs are involved in suspend
6679 * resume sequence. As long as this is not the last online
6680 * operation in the resume sequence, just build a single sched
6681 * domain, ignoring cpusets.
6682 */
6683 num_cpus_frozen--;
6684 if (likely(num_cpus_frozen)) {
6685 partition_sched_domains(1, NULL, NULL);
6686 break;
6687 }
6688
6689 /*
6690 * This is the last CPU online operation. So fall through and
6691 * restore the original sched domains by considering the
6692 * cpuset configurations.
6693 */
6694
6695 case CPU_ONLINE:
6696 case CPU_DOWN_FAILED:
6697 cpuset_update_active_cpus(true);
6698 break;
6699 default:
6700 return NOTIFY_DONE;
6701 }
6702 return NOTIFY_OK;
6703}
6704
6705static int cpuset_cpu_inactive(struct notifier_block *nfb, unsigned long action,
6706 void *hcpu)
6707{
6708 switch (action) {
6709 case CPU_DOWN_PREPARE:
6710 cpuset_update_active_cpus(false);
6711 break;
6712 case CPU_DOWN_PREPARE_FROZEN:
6713 num_cpus_frozen++;
6714 partition_sched_domains(1, NULL, NULL);
6715 break;
6716 default:
6717 return NOTIFY_DONE;
6718 }
6719 return NOTIFY_OK;
6720}
6721
6722void __init sched_init_smp(void)
6723{
6724 cpumask_var_t non_isolated_cpus;
6725
6726 alloc_cpumask_var(&non_isolated_cpus, GFP_KERNEL);
6727 alloc_cpumask_var(&fallback_doms, GFP_KERNEL);
6728
6729 sched_init_numa();
6730
6731 /*
6732 * There's no userspace yet to cause hotplug operations; hence all the
6733 * cpu masks are stable and all blatant races in the below code cannot
6734 * happen.
6735 */
6736 mutex_lock(&sched_domains_mutex);
6737 init_sched_domains(cpu_active_mask);
6738 cpumask_andnot(non_isolated_cpus, cpu_possible_mask, cpu_isolated_map);
6739 if (cpumask_empty(non_isolated_cpus))
6740 cpumask_set_cpu(smp_processor_id(), non_isolated_cpus);
6741 mutex_unlock(&sched_domains_mutex);
6742
6743 hotcpu_notifier(sched_domains_numa_masks_update, CPU_PRI_SCHED_ACTIVE);
6744 hotcpu_notifier(cpuset_cpu_active, CPU_PRI_CPUSET_ACTIVE);
6745 hotcpu_notifier(cpuset_cpu_inactive, CPU_PRI_CPUSET_INACTIVE);
6746
6747 init_hrtick();
6748
6749 /* Move init over to a non-isolated CPU */
6750 if (set_cpus_allowed_ptr(current, non_isolated_cpus) < 0)
6751 BUG();
6752 sched_init_granularity();
6753 free_cpumask_var(non_isolated_cpus);
6754
6755 init_sched_rt_class();
6756 init_sched_dl_class();
6757}
6758#else
6759void __init sched_init_smp(void)
6760{
6761 sched_init_granularity();
6762}
6763#endif /* CONFIG_SMP */
6764
6765const_debug unsigned int sysctl_timer_migration = 1;
6766
6767int in_sched_functions(unsigned long addr)
6768{
6769 return in_lock_functions(addr) ||
6770 (addr >= (unsigned long)__sched_text_start
6771 && addr < (unsigned long)__sched_text_end);
6772}
6773
6774#ifdef CONFIG_CGROUP_SCHED
6775/*
6776 * Default task group.
6777 * Every task in system belongs to this group at bootup.
6778 */
6779struct task_group root_task_group;
6780LIST_HEAD(task_groups);
6781#endif
6782
6783DECLARE_PER_CPU(cpumask_var_t, load_balance_mask);
6784
6785void __init sched_init(void)
6786{
6787 int i, j;
6788 unsigned long alloc_size = 0, ptr;
6789
6790#ifdef CONFIG_FAIR_GROUP_SCHED
6791 alloc_size += 2 * nr_cpu_ids * sizeof(void **);
6792#endif
6793#ifdef CONFIG_RT_GROUP_SCHED
6794 alloc_size += 2 * nr_cpu_ids * sizeof(void **);
6795#endif
6796#ifdef CONFIG_CPUMASK_OFFSTACK
6797 alloc_size += num_possible_cpus() * cpumask_size();
6798#endif
6799 if (alloc_size) {
6800 ptr = (unsigned long)kzalloc(alloc_size, GFP_NOWAIT);
6801
6802#ifdef CONFIG_FAIR_GROUP_SCHED
6803 root_task_group.se = (struct sched_entity **)ptr;
6804 ptr += nr_cpu_ids * sizeof(void **);
6805
6806 root_task_group.cfs_rq = (struct cfs_rq **)ptr;
6807 ptr += nr_cpu_ids * sizeof(void **);
6808
6809#endif /* CONFIG_FAIR_GROUP_SCHED */
6810#ifdef CONFIG_RT_GROUP_SCHED
6811 root_task_group.rt_se = (struct sched_rt_entity **)ptr;
6812 ptr += nr_cpu_ids * sizeof(void **);
6813
6814 root_task_group.rt_rq = (struct rt_rq **)ptr;
6815 ptr += nr_cpu_ids * sizeof(void **);
6816
6817#endif /* CONFIG_RT_GROUP_SCHED */
6818#ifdef CONFIG_CPUMASK_OFFSTACK
6819 for_each_possible_cpu(i) {
6820 per_cpu(load_balance_mask, i) = (void *)ptr;
6821 ptr += cpumask_size();
6822 }
6823#endif /* CONFIG_CPUMASK_OFFSTACK */
6824 }
6825
6826 init_rt_bandwidth(&def_rt_bandwidth,
6827 global_rt_period(), global_rt_runtime());
6828 init_dl_bandwidth(&def_dl_bandwidth,
6829 global_rt_period(), global_rt_runtime());
6830
6831#ifdef CONFIG_SMP
6832 init_defrootdomain();
6833#endif
6834
6835#ifdef CONFIG_RT_GROUP_SCHED
6836 init_rt_bandwidth(&root_task_group.rt_bandwidth,
6837 global_rt_period(), global_rt_runtime());
6838#endif /* CONFIG_RT_GROUP_SCHED */
6839
6840#ifdef CONFIG_CGROUP_SCHED
6841 list_add(&root_task_group.list, &task_groups);
6842 INIT_LIST_HEAD(&root_task_group.children);
6843 INIT_LIST_HEAD(&root_task_group.siblings);
6844 autogroup_init(&init_task);
6845
6846#endif /* CONFIG_CGROUP_SCHED */
6847
6848 for_each_possible_cpu(i) {
6849 struct rq *rq;
6850
6851 rq = cpu_rq(i);
6852 raw_spin_lock_init(&rq->lock);
6853 rq->nr_running = 0;
6854 rq->calc_load_active = 0;
6855 rq->calc_load_update = jiffies + LOAD_FREQ;
6856 init_cfs_rq(&rq->cfs);
6857 init_rt_rq(&rq->rt, rq);
6858 init_dl_rq(&rq->dl, rq);
6859#ifdef CONFIG_FAIR_GROUP_SCHED
6860 root_task_group.shares = ROOT_TASK_GROUP_LOAD;
6861 INIT_LIST_HEAD(&rq->leaf_cfs_rq_list);
6862 /*
6863 * How much cpu bandwidth does root_task_group get?
6864 *
6865 * In case of task-groups formed thr' the cgroup filesystem, it
6866 * gets 100% of the cpu resources in the system. This overall
6867 * system cpu resource is divided among the tasks of
6868 * root_task_group and its child task-groups in a fair manner,
6869 * based on each entity's (task or task-group's) weight
6870 * (se->load.weight).
6871 *
6872 * In other words, if root_task_group has 10 tasks of weight
6873 * 1024) and two child groups A0 and A1 (of weight 1024 each),
6874 * then A0's share of the cpu resource is:
6875 *
6876 * A0's bandwidth = 1024 / (10*1024 + 1024 + 1024) = 8.33%
6877 *
6878 * We achieve this by letting root_task_group's tasks sit
6879 * directly in rq->cfs (i.e root_task_group->se[] = NULL).
6880 */
6881 init_cfs_bandwidth(&root_task_group.cfs_bandwidth);
6882 init_tg_cfs_entry(&root_task_group, &rq->cfs, NULL, i, NULL);
6883#endif /* CONFIG_FAIR_GROUP_SCHED */
6884
6885 rq->rt.rt_runtime = def_rt_bandwidth.rt_runtime;
6886#ifdef CONFIG_RT_GROUP_SCHED
6887 init_tg_rt_entry(&root_task_group, &rq->rt, NULL, i, NULL);
6888#endif
6889
6890 for (j = 0; j < CPU_LOAD_IDX_MAX; j++)
6891 rq->cpu_load[j] = 0;
6892
6893 rq->last_load_update_tick = jiffies;
6894
6895#ifdef CONFIG_SMP
6896 rq->sd = NULL;
6897 rq->rd = NULL;
6898 rq->cpu_power = SCHED_POWER_SCALE;
6899 rq->post_schedule = 0;
6900 rq->active_balance = 0;
6901 rq->next_balance = jiffies;
6902 rq->push_cpu = 0;
6903 rq->cpu = i;
6904 rq->online = 0;
6905 rq->idle_stamp = 0;
6906 rq->avg_idle = 2*sysctl_sched_migration_cost;
6907 rq->max_idle_balance_cost = sysctl_sched_migration_cost;
6908
6909 INIT_LIST_HEAD(&rq->cfs_tasks);
6910
6911 rq_attach_root(rq, &def_root_domain);
6912#ifdef CONFIG_NO_HZ_COMMON
6913 rq->nohz_flags = 0;
6914#endif
6915#ifdef CONFIG_NO_HZ_FULL
6916 rq->last_sched_tick = 0;
6917#endif
6918#endif
6919 init_rq_hrtick(rq);
6920 atomic_set(&rq->nr_iowait, 0);
6921 }
6922
6923 set_load_weight(&init_task);
6924
6925#ifdef CONFIG_PREEMPT_NOTIFIERS
6926 INIT_HLIST_HEAD(&init_task.preempt_notifiers);
6927#endif
6928
6929 /*
6930 * The boot idle thread does lazy MMU switching as well:
6931 */
6932 atomic_inc(&init_mm.mm_count);
6933 enter_lazy_tlb(&init_mm, current);
6934
6935 /*
6936 * Make us the idle thread. Technically, schedule() should not be
6937 * called from this thread, however somewhere below it might be,
6938 * but because we are the idle thread, we just pick up running again
6939 * when this runqueue becomes "idle".
6940 */
6941 init_idle(current, smp_processor_id());
6942
6943 calc_load_update = jiffies + LOAD_FREQ;
6944
6945 /*
6946 * During early bootup we pretend to be a normal task:
6947 */
6948 current->sched_class = &fair_sched_class;
6949
6950#ifdef CONFIG_SMP
6951 zalloc_cpumask_var(&sched_domains_tmpmask, GFP_NOWAIT);
6952 /* May be allocated at isolcpus cmdline parse time */
6953 if (cpu_isolated_map == NULL)
6954 zalloc_cpumask_var(&cpu_isolated_map, GFP_NOWAIT);
6955 idle_thread_set_boot_cpu();
6956#endif
6957 init_sched_fair_class();
6958
6959 scheduler_running = 1;
6960}
6961
6962#ifdef CONFIG_DEBUG_ATOMIC_SLEEP
6963static inline int preempt_count_equals(int preempt_offset)
6964{
6965 int nested = (preempt_count() & ~PREEMPT_ACTIVE) + rcu_preempt_depth();
6966
6967 return (nested == preempt_offset);
6968}
6969
6970void __might_sleep(const char *file, int line, int preempt_offset)
6971{
6972 static unsigned long prev_jiffy; /* ratelimiting */
6973
6974 rcu_sleep_check(); /* WARN_ON_ONCE() by default, no rate limit reqd. */
6975 if ((preempt_count_equals(preempt_offset) && !irqs_disabled() &&
6976 !is_idle_task(current)) ||
6977 system_state != SYSTEM_RUNNING || oops_in_progress)
6978 return;
6979 if (time_before(jiffies, prev_jiffy + HZ) && prev_jiffy)
6980 return;
6981 prev_jiffy = jiffies;
6982
6983 printk(KERN_ERR
6984 "BUG: sleeping function called from invalid context at %s:%d\n",
6985 file, line);
6986 printk(KERN_ERR
6987 "in_atomic(): %d, irqs_disabled(): %d, pid: %d, name: %s\n",
6988 in_atomic(), irqs_disabled(),
6989 current->pid, current->comm);
6990
6991 debug_show_held_locks(current);
6992 if (irqs_disabled())
6993 print_irqtrace_events(current);
6994#ifdef CONFIG_DEBUG_PREEMPT
6995 if (!preempt_count_equals(preempt_offset)) {
6996 pr_err("Preemption disabled at:");
6997 print_ip_sym(current->preempt_disable_ip);
6998 pr_cont("\n");
6999 }
7000#endif
7001 dump_stack();
7002}
7003EXPORT_SYMBOL(__might_sleep);
7004#endif
7005
7006#ifdef CONFIG_MAGIC_SYSRQ
7007static void normalize_task(struct rq *rq, struct task_struct *p)
7008{
7009 const struct sched_class *prev_class = p->sched_class;
7010 struct sched_attr attr = {
7011 .sched_policy = SCHED_NORMAL,
7012 };
7013 int old_prio = p->prio;
7014 int on_rq;
7015
7016 on_rq = p->on_rq;
7017 if (on_rq)
7018 dequeue_task(rq, p, 0);
7019 __setscheduler(rq, p, &attr);
7020 if (on_rq) {
7021 enqueue_task(rq, p, 0);
7022 resched_task(rq->curr);
7023 }
7024
7025 check_class_changed(rq, p, prev_class, old_prio);
7026}
7027
7028void normalize_rt_tasks(void)
7029{
7030 struct task_struct *g, *p;
7031 unsigned long flags;
7032 struct rq *rq;
7033
7034 read_lock_irqsave(&tasklist_lock, flags);
7035 do_each_thread(g, p) {
7036 /*
7037 * Only normalize user tasks:
7038 */
7039 if (!p->mm)
7040 continue;
7041
7042 p->se.exec_start = 0;
7043#ifdef CONFIG_SCHEDSTATS
7044 p->se.statistics.wait_start = 0;
7045 p->se.statistics.sleep_start = 0;
7046 p->se.statistics.block_start = 0;
7047#endif
7048
7049 if (!dl_task(p) && !rt_task(p)) {
7050 /*
7051 * Renice negative nice level userspace
7052 * tasks back to 0:
7053 */
7054 if (task_nice(p) < 0 && p->mm)
7055 set_user_nice(p, 0);
7056 continue;
7057 }
7058
7059 raw_spin_lock(&p->pi_lock);
7060 rq = __task_rq_lock(p);
7061
7062 normalize_task(rq, p);
7063
7064 __task_rq_unlock(rq);
7065 raw_spin_unlock(&p->pi_lock);
7066 } while_each_thread(g, p);
7067
7068 read_unlock_irqrestore(&tasklist_lock, flags);
7069}
7070
7071#endif /* CONFIG_MAGIC_SYSRQ */
7072
7073#if defined(CONFIG_IA64) || defined(CONFIG_KGDB_KDB)
7074/*
7075 * These functions are only useful for the IA64 MCA handling, or kdb.
7076 *
7077 * They can only be called when the whole system has been
7078 * stopped - every CPU needs to be quiescent, and no scheduling
7079 * activity can take place. Using them for anything else would
7080 * be a serious bug, and as a result, they aren't even visible
7081 * under any other configuration.
7082 */
7083
7084/**
7085 * curr_task - return the current task for a given cpu.
7086 * @cpu: the processor in question.
7087 *
7088 * ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED!
7089 *
7090 * Return: The current task for @cpu.
7091 */
7092struct task_struct *curr_task(int cpu)
7093{
7094 return cpu_curr(cpu);
7095}
7096
7097#endif /* defined(CONFIG_IA64) || defined(CONFIG_KGDB_KDB) */
7098
7099#ifdef CONFIG_IA64
7100/**
7101 * set_curr_task - set the current task for a given cpu.
7102 * @cpu: the processor in question.
7103 * @p: the task pointer to set.
7104 *
7105 * Description: This function must only be used when non-maskable interrupts
7106 * are serviced on a separate stack. It allows the architecture to switch the
7107 * notion of the current task on a cpu in a non-blocking manner. This function
7108 * must be called with all CPU's synchronized, and interrupts disabled, the
7109 * and caller must save the original value of the current task (see
7110 * curr_task() above) and restore that value before reenabling interrupts and
7111 * re-starting the system.
7112 *
7113 * ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED!
7114 */
7115void set_curr_task(int cpu, struct task_struct *p)
7116{
7117 cpu_curr(cpu) = p;
7118}
7119
7120#endif
7121
7122#ifdef CONFIG_CGROUP_SCHED
7123/* task_group_lock serializes the addition/removal of task groups */
7124static DEFINE_SPINLOCK(task_group_lock);
7125
7126static void free_sched_group(struct task_group *tg)
7127{
7128 free_fair_sched_group(tg);
7129 free_rt_sched_group(tg);
7130 autogroup_free(tg);
7131 kfree(tg);
7132}
7133
7134/* allocate runqueue etc for a new task group */
7135struct task_group *sched_create_group(struct task_group *parent)
7136{
7137 struct task_group *tg;
7138
7139 tg = kzalloc(sizeof(*tg), GFP_KERNEL);
7140 if (!tg)
7141 return ERR_PTR(-ENOMEM);
7142
7143 if (!alloc_fair_sched_group(tg, parent))
7144 goto err;
7145
7146 if (!alloc_rt_sched_group(tg, parent))
7147 goto err;
7148
7149 return tg;
7150
7151err:
7152 free_sched_group(tg);
7153 return ERR_PTR(-ENOMEM);
7154}
7155
7156void sched_online_group(struct task_group *tg, struct task_group *parent)
7157{
7158 unsigned long flags;
7159
7160 spin_lock_irqsave(&task_group_lock, flags);
7161 list_add_rcu(&tg->list, &task_groups);
7162
7163 WARN_ON(!parent); /* root should already exist */
7164
7165 tg->parent = parent;
7166 INIT_LIST_HEAD(&tg->children);
7167 list_add_rcu(&tg->siblings, &parent->children);
7168 spin_unlock_irqrestore(&task_group_lock, flags);
7169}
7170
7171/* rcu callback to free various structures associated with a task group */
7172static void free_sched_group_rcu(struct rcu_head *rhp)
7173{
7174 /* now it should be safe to free those cfs_rqs */
7175 free_sched_group(container_of(rhp, struct task_group, rcu));
7176}
7177
7178/* Destroy runqueue etc associated with a task group */
7179void sched_destroy_group(struct task_group *tg)
7180{
7181 /* wait for possible concurrent references to cfs_rqs complete */
7182 call_rcu(&tg->rcu, free_sched_group_rcu);
7183}
7184
7185void sched_offline_group(struct task_group *tg)
7186{
7187 unsigned long flags;
7188 int i;
7189
7190 /* end participation in shares distribution */
7191 for_each_possible_cpu(i)
7192 unregister_fair_sched_group(tg, i);
7193
7194 spin_lock_irqsave(&task_group_lock, flags);
7195 list_del_rcu(&tg->list);
7196 list_del_rcu(&tg->siblings);
7197 spin_unlock_irqrestore(&task_group_lock, flags);
7198}
7199
7200/* change task's runqueue when it moves between groups.
7201 * The caller of this function should have put the task in its new group
7202 * by now. This function just updates tsk->se.cfs_rq and tsk->se.parent to
7203 * reflect its new group.
7204 */
7205void sched_move_task(struct task_struct *tsk)
7206{
7207 struct task_group *tg;
7208 int on_rq, running;
7209 unsigned long flags;
7210 struct rq *rq;
7211
7212 rq = task_rq_lock(tsk, &flags);
7213
7214 running = task_current(rq, tsk);
7215 on_rq = tsk->on_rq;
7216
7217 if (on_rq)
7218 dequeue_task(rq, tsk, 0);
7219 if (unlikely(running))
7220 tsk->sched_class->put_prev_task(rq, tsk);
7221
7222 tg = container_of(task_css_check(tsk, cpu_cgrp_id,
7223 lockdep_is_held(&tsk->sighand->siglock)),
7224 struct task_group, css);
7225 tg = autogroup_task_group(tsk, tg);
7226 tsk->sched_task_group = tg;
7227
7228#ifdef CONFIG_FAIR_GROUP_SCHED
7229 if (tsk->sched_class->task_move_group)
7230 tsk->sched_class->task_move_group(tsk, on_rq);
7231 else
7232#endif
7233 set_task_rq(tsk, task_cpu(tsk));
7234
7235 if (unlikely(running))
7236 tsk->sched_class->set_curr_task(rq);
7237 if (on_rq)
7238 enqueue_task(rq, tsk, 0);
7239
7240 task_rq_unlock(rq, tsk, &flags);
7241}
7242#endif /* CONFIG_CGROUP_SCHED */
7243
7244#ifdef CONFIG_RT_GROUP_SCHED
7245/*
7246 * Ensure that the real time constraints are schedulable.
7247 */
7248static DEFINE_MUTEX(rt_constraints_mutex);
7249
7250/* Must be called with tasklist_lock held */
7251static inline int tg_has_rt_tasks(struct task_group *tg)
7252{
7253 struct task_struct *g, *p;
7254
7255 do_each_thread(g, p) {
7256 if (rt_task(p) && task_rq(p)->rt.tg == tg)
7257 return 1;
7258 } while_each_thread(g, p);
7259
7260 return 0;
7261}
7262
7263struct rt_schedulable_data {
7264 struct task_group *tg;
7265 u64 rt_period;
7266 u64 rt_runtime;
7267};
7268
7269static int tg_rt_schedulable(struct task_group *tg, void *data)
7270{
7271 struct rt_schedulable_data *d = data;
7272 struct task_group *child;
7273 unsigned long total, sum = 0;
7274 u64 period, runtime;
7275
7276 period = ktime_to_ns(tg->rt_bandwidth.rt_period);
7277 runtime = tg->rt_bandwidth.rt_runtime;
7278
7279 if (tg == d->tg) {
7280 period = d->rt_period;
7281 runtime = d->rt_runtime;
7282 }
7283
7284 /*
7285 * Cannot have more runtime than the period.
7286 */
7287 if (runtime > period && runtime != RUNTIME_INF)
7288 return -EINVAL;
7289
7290 /*
7291 * Ensure we don't starve existing RT tasks.
7292 */
7293 if (rt_bandwidth_enabled() && !runtime && tg_has_rt_tasks(tg))
7294 return -EBUSY;
7295
7296 total = to_ratio(period, runtime);
7297
7298 /*
7299 * Nobody can have more than the global setting allows.
7300 */
7301 if (total > to_ratio(global_rt_period(), global_rt_runtime()))
7302 return -EINVAL;
7303
7304 /*
7305 * The sum of our children's runtime should not exceed our own.
7306 */
7307 list_for_each_entry_rcu(child, &tg->children, siblings) {
7308 period = ktime_to_ns(child->rt_bandwidth.rt_period);
7309 runtime = child->rt_bandwidth.rt_runtime;
7310
7311 if (child == d->tg) {
7312 period = d->rt_period;
7313 runtime = d->rt_runtime;
7314 }
7315
7316 sum += to_ratio(period, runtime);
7317 }
7318
7319 if (sum > total)
7320 return -EINVAL;
7321
7322 return 0;
7323}
7324
7325static int __rt_schedulable(struct task_group *tg, u64 period, u64 runtime)
7326{
7327 int ret;
7328
7329 struct rt_schedulable_data data = {
7330 .tg = tg,
7331 .rt_period = period,
7332 .rt_runtime = runtime,
7333 };
7334
7335 rcu_read_lock();
7336 ret = walk_tg_tree(tg_rt_schedulable, tg_nop, &data);
7337 rcu_read_unlock();
7338
7339 return ret;
7340}
7341
7342static int tg_set_rt_bandwidth(struct task_group *tg,
7343 u64 rt_period, u64 rt_runtime)
7344{
7345 int i, err = 0;
7346
7347 mutex_lock(&rt_constraints_mutex);
7348 read_lock(&tasklist_lock);
7349 err = __rt_schedulable(tg, rt_period, rt_runtime);
7350 if (err)
7351 goto unlock;
7352
7353 raw_spin_lock_irq(&tg->rt_bandwidth.rt_runtime_lock);
7354 tg->rt_bandwidth.rt_period = ns_to_ktime(rt_period);
7355 tg->rt_bandwidth.rt_runtime = rt_runtime;
7356
7357 for_each_possible_cpu(i) {
7358 struct rt_rq *rt_rq = tg->rt_rq[i];
7359
7360 raw_spin_lock(&rt_rq->rt_runtime_lock);
7361 rt_rq->rt_runtime = rt_runtime;
7362 raw_spin_unlock(&rt_rq->rt_runtime_lock);
7363 }
7364 raw_spin_unlock_irq(&tg->rt_bandwidth.rt_runtime_lock);
7365unlock:
7366 read_unlock(&tasklist_lock);
7367 mutex_unlock(&rt_constraints_mutex);
7368
7369 return err;
7370}
7371
7372static int sched_group_set_rt_runtime(struct task_group *tg, long rt_runtime_us)
7373{
7374 u64 rt_runtime, rt_period;
7375
7376 rt_period = ktime_to_ns(tg->rt_bandwidth.rt_period);
7377 rt_runtime = (u64)rt_runtime_us * NSEC_PER_USEC;
7378 if (rt_runtime_us < 0)
7379 rt_runtime = RUNTIME_INF;
7380
7381 return tg_set_rt_bandwidth(tg, rt_period, rt_runtime);
7382}
7383
7384static long sched_group_rt_runtime(struct task_group *tg)
7385{
7386 u64 rt_runtime_us;
7387
7388 if (tg->rt_bandwidth.rt_runtime == RUNTIME_INF)
7389 return -1;
7390
7391 rt_runtime_us = tg->rt_bandwidth.rt_runtime;
7392 do_div(rt_runtime_us, NSEC_PER_USEC);
7393 return rt_runtime_us;
7394}
7395
7396static int sched_group_set_rt_period(struct task_group *tg, long rt_period_us)
7397{
7398 u64 rt_runtime, rt_period;
7399
7400 rt_period = (u64)rt_period_us * NSEC_PER_USEC;
7401 rt_runtime = tg->rt_bandwidth.rt_runtime;
7402
7403 if (rt_period == 0)
7404 return -EINVAL;
7405
7406 return tg_set_rt_bandwidth(tg, rt_period, rt_runtime);
7407}
7408
7409static long sched_group_rt_period(struct task_group *tg)
7410{
7411 u64 rt_period_us;
7412
7413 rt_period_us = ktime_to_ns(tg->rt_bandwidth.rt_period);
7414 do_div(rt_period_us, NSEC_PER_USEC);
7415 return rt_period_us;
7416}
7417#endif /* CONFIG_RT_GROUP_SCHED */
7418
7419#ifdef CONFIG_RT_GROUP_SCHED
7420static int sched_rt_global_constraints(void)
7421{
7422 int ret = 0;
7423
7424 mutex_lock(&rt_constraints_mutex);
7425 read_lock(&tasklist_lock);
7426 ret = __rt_schedulable(NULL, 0, 0);
7427 read_unlock(&tasklist_lock);
7428 mutex_unlock(&rt_constraints_mutex);
7429
7430 return ret;
7431}
7432
7433static int sched_rt_can_attach(struct task_group *tg, struct task_struct *tsk)
7434{
7435 /* Don't accept realtime tasks when there is no way for them to run */
7436 if (rt_task(tsk) && tg->rt_bandwidth.rt_runtime == 0)
7437 return 0;
7438
7439 return 1;
7440}
7441
7442#else /* !CONFIG_RT_GROUP_SCHED */
7443static int sched_rt_global_constraints(void)
7444{
7445 unsigned long flags;
7446 int i, ret = 0;
7447
7448 raw_spin_lock_irqsave(&def_rt_bandwidth.rt_runtime_lock, flags);
7449 for_each_possible_cpu(i) {
7450 struct rt_rq *rt_rq = &cpu_rq(i)->rt;
7451
7452 raw_spin_lock(&rt_rq->rt_runtime_lock);
7453 rt_rq->rt_runtime = global_rt_runtime();
7454 raw_spin_unlock(&rt_rq->rt_runtime_lock);
7455 }
7456 raw_spin_unlock_irqrestore(&def_rt_bandwidth.rt_runtime_lock, flags);
7457
7458 return ret;
7459}
7460#endif /* CONFIG_RT_GROUP_SCHED */
7461
7462static int sched_dl_global_constraints(void)
7463{
7464 u64 runtime = global_rt_runtime();
7465 u64 period = global_rt_period();
7466 u64 new_bw = to_ratio(period, runtime);
7467 int cpu, ret = 0;
7468 unsigned long flags;
7469
7470 /*
7471 * Here we want to check the bandwidth not being set to some
7472 * value smaller than the currently allocated bandwidth in
7473 * any of the root_domains.
7474 *
7475 * FIXME: Cycling on all the CPUs is overdoing, but simpler than
7476 * cycling on root_domains... Discussion on different/better
7477 * solutions is welcome!
7478 */
7479 for_each_possible_cpu(cpu) {
7480 struct dl_bw *dl_b = dl_bw_of(cpu);
7481
7482 raw_spin_lock_irqsave(&dl_b->lock, flags);
7483 if (new_bw < dl_b->total_bw)
7484 ret = -EBUSY;
7485 raw_spin_unlock_irqrestore(&dl_b->lock, flags);
7486
7487 if (ret)
7488 break;
7489 }
7490
7491 return ret;
7492}
7493
7494static void sched_dl_do_global(void)
7495{
7496 u64 new_bw = -1;
7497 int cpu;
7498 unsigned long flags;
7499
7500 def_dl_bandwidth.dl_period = global_rt_period();
7501 def_dl_bandwidth.dl_runtime = global_rt_runtime();
7502
7503 if (global_rt_runtime() != RUNTIME_INF)
7504 new_bw = to_ratio(global_rt_period(), global_rt_runtime());
7505
7506 /*
7507 * FIXME: As above...
7508 */
7509 for_each_possible_cpu(cpu) {
7510 struct dl_bw *dl_b = dl_bw_of(cpu);
7511
7512 raw_spin_lock_irqsave(&dl_b->lock, flags);
7513 dl_b->bw = new_bw;
7514 raw_spin_unlock_irqrestore(&dl_b->lock, flags);
7515 }
7516}
7517
7518static int sched_rt_global_validate(void)
7519{
7520 if (sysctl_sched_rt_period <= 0)
7521 return -EINVAL;
7522
7523 if ((sysctl_sched_rt_runtime != RUNTIME_INF) &&
7524 (sysctl_sched_rt_runtime > sysctl_sched_rt_period))
7525 return -EINVAL;
7526
7527 return 0;
7528}
7529
7530static void sched_rt_do_global(void)
7531{
7532 def_rt_bandwidth.rt_runtime = global_rt_runtime();
7533 def_rt_bandwidth.rt_period = ns_to_ktime(global_rt_period());
7534}
7535
7536int sched_rt_handler(struct ctl_table *table, int write,
7537 void __user *buffer, size_t *lenp,
7538 loff_t *ppos)
7539{
7540 int old_period, old_runtime;
7541 static DEFINE_MUTEX(mutex);
7542 int ret;
7543
7544 mutex_lock(&mutex);
7545 old_period = sysctl_sched_rt_period;
7546 old_runtime = sysctl_sched_rt_runtime;
7547
7548 ret = proc_dointvec(table, write, buffer, lenp, ppos);
7549
7550 if (!ret && write) {
7551 ret = sched_rt_global_validate();
7552 if (ret)
7553 goto undo;
7554
7555 ret = sched_rt_global_constraints();
7556 if (ret)
7557 goto undo;
7558
7559 ret = sched_dl_global_constraints();
7560 if (ret)
7561 goto undo;
7562
7563 sched_rt_do_global();
7564 sched_dl_do_global();
7565 }
7566 if (0) {
7567undo:
7568 sysctl_sched_rt_period = old_period;
7569 sysctl_sched_rt_runtime = old_runtime;
7570 }
7571 mutex_unlock(&mutex);
7572
7573 return ret;
7574}
7575
7576int sched_rr_handler(struct ctl_table *table, int write,
7577 void __user *buffer, size_t *lenp,
7578 loff_t *ppos)
7579{
7580 int ret;
7581 static DEFINE_MUTEX(mutex);
7582
7583 mutex_lock(&mutex);
7584 ret = proc_dointvec(table, write, buffer, lenp, ppos);
7585 /* make sure that internally we keep jiffies */
7586 /* also, writing zero resets timeslice to default */
7587 if (!ret && write) {
7588 sched_rr_timeslice = sched_rr_timeslice <= 0 ?
7589 RR_TIMESLICE : msecs_to_jiffies(sched_rr_timeslice);
7590 }
7591 mutex_unlock(&mutex);
7592 return ret;
7593}
7594
7595#ifdef CONFIG_CGROUP_SCHED
7596
7597static inline struct task_group *css_tg(struct cgroup_subsys_state *css)
7598{
7599 return css ? container_of(css, struct task_group, css) : NULL;
7600}
7601
7602static struct cgroup_subsys_state *
7603cpu_cgroup_css_alloc(struct cgroup_subsys_state *parent_css)
7604{
7605 struct task_group *parent = css_tg(parent_css);
7606 struct task_group *tg;
7607
7608 if (!parent) {
7609 /* This is early initialization for the top cgroup */
7610 return &root_task_group.css;
7611 }
7612
7613 tg = sched_create_group(parent);
7614 if (IS_ERR(tg))
7615 return ERR_PTR(-ENOMEM);
7616
7617 return &tg->css;
7618}
7619
7620static int cpu_cgroup_css_online(struct cgroup_subsys_state *css)
7621{
7622 struct task_group *tg = css_tg(css);
7623 struct task_group *parent = css_tg(css_parent(css));
7624
7625 if (parent)
7626 sched_online_group(tg, parent);
7627 return 0;
7628}
7629
7630static void cpu_cgroup_css_free(struct cgroup_subsys_state *css)
7631{
7632 struct task_group *tg = css_tg(css);
7633
7634 sched_destroy_group(tg);
7635}
7636
7637static void cpu_cgroup_css_offline(struct cgroup_subsys_state *css)
7638{
7639 struct task_group *tg = css_tg(css);
7640
7641 sched_offline_group(tg);
7642}
7643
7644static int cpu_cgroup_can_attach(struct cgroup_subsys_state *css,
7645 struct cgroup_taskset *tset)
7646{
7647 struct task_struct *task;
7648
7649 cgroup_taskset_for_each(task, tset) {
7650#ifdef CONFIG_RT_GROUP_SCHED
7651 if (!sched_rt_can_attach(css_tg(css), task))
7652 return -EINVAL;
7653#else
7654 /* We don't support RT-tasks being in separate groups */
7655 if (task->sched_class != &fair_sched_class)
7656 return -EINVAL;
7657#endif
7658 }
7659 return 0;
7660}
7661
7662static void cpu_cgroup_attach(struct cgroup_subsys_state *css,
7663 struct cgroup_taskset *tset)
7664{
7665 struct task_struct *task;
7666
7667 cgroup_taskset_for_each(task, tset)
7668 sched_move_task(task);
7669}
7670
7671static void cpu_cgroup_exit(struct cgroup_subsys_state *css,
7672 struct cgroup_subsys_state *old_css,
7673 struct task_struct *task)
7674{
7675 /*
7676 * cgroup_exit() is called in the copy_process() failure path.
7677 * Ignore this case since the task hasn't ran yet, this avoids
7678 * trying to poke a half freed task state from generic code.
7679 */
7680 if (!(task->flags & PF_EXITING))
7681 return;
7682
7683 sched_move_task(task);
7684}
7685
7686#ifdef CONFIG_FAIR_GROUP_SCHED
7687static int cpu_shares_write_u64(struct cgroup_subsys_state *css,
7688 struct cftype *cftype, u64 shareval)
7689{
7690 return sched_group_set_shares(css_tg(css), scale_load(shareval));
7691}
7692
7693static u64 cpu_shares_read_u64(struct cgroup_subsys_state *css,
7694 struct cftype *cft)
7695{
7696 struct task_group *tg = css_tg(css);
7697
7698 return (u64) scale_load_down(tg->shares);
7699}
7700
7701#ifdef CONFIG_CFS_BANDWIDTH
7702static DEFINE_MUTEX(cfs_constraints_mutex);
7703
7704const u64 max_cfs_quota_period = 1 * NSEC_PER_SEC; /* 1s */
7705const u64 min_cfs_quota_period = 1 * NSEC_PER_MSEC; /* 1ms */
7706
7707static int __cfs_schedulable(struct task_group *tg, u64 period, u64 runtime);
7708
7709static int tg_set_cfs_bandwidth(struct task_group *tg, u64 period, u64 quota)
7710{
7711 int i, ret = 0, runtime_enabled, runtime_was_enabled;
7712 struct cfs_bandwidth *cfs_b = &tg->cfs_bandwidth;
7713
7714 if (tg == &root_task_group)
7715 return -EINVAL;
7716
7717 /*
7718 * Ensure we have at some amount of bandwidth every period. This is
7719 * to prevent reaching a state of large arrears when throttled via
7720 * entity_tick() resulting in prolonged exit starvation.
7721 */
7722 if (quota < min_cfs_quota_period || period < min_cfs_quota_period)
7723 return -EINVAL;
7724
7725 /*
7726 * Likewise, bound things on the otherside by preventing insane quota
7727 * periods. This also allows us to normalize in computing quota
7728 * feasibility.
7729 */
7730 if (period > max_cfs_quota_period)
7731 return -EINVAL;
7732
7733 mutex_lock(&cfs_constraints_mutex);
7734 ret = __cfs_schedulable(tg, period, quota);
7735 if (ret)
7736 goto out_unlock;
7737
7738 runtime_enabled = quota != RUNTIME_INF;
7739 runtime_was_enabled = cfs_b->quota != RUNTIME_INF;
7740 /*
7741 * If we need to toggle cfs_bandwidth_used, off->on must occur
7742 * before making related changes, and on->off must occur afterwards
7743 */
7744 if (runtime_enabled && !runtime_was_enabled)
7745 cfs_bandwidth_usage_inc();
7746 raw_spin_lock_irq(&cfs_b->lock);
7747 cfs_b->period = ns_to_ktime(period);
7748 cfs_b->quota = quota;
7749
7750 __refill_cfs_bandwidth_runtime(cfs_b);
7751 /* restart the period timer (if active) to handle new period expiry */
7752 if (runtime_enabled && cfs_b->timer_active) {
7753 /* force a reprogram */
7754 __start_cfs_bandwidth(cfs_b, true);
7755 }
7756 raw_spin_unlock_irq(&cfs_b->lock);
7757
7758 for_each_possible_cpu(i) {
7759 struct cfs_rq *cfs_rq = tg->cfs_rq[i];
7760 struct rq *rq = cfs_rq->rq;
7761
7762 raw_spin_lock_irq(&rq->lock);
7763 cfs_rq->runtime_enabled = runtime_enabled;
7764 cfs_rq->runtime_remaining = 0;
7765
7766 if (cfs_rq->throttled)
7767 unthrottle_cfs_rq(cfs_rq);
7768 raw_spin_unlock_irq(&rq->lock);
7769 }
7770 if (runtime_was_enabled && !runtime_enabled)
7771 cfs_bandwidth_usage_dec();
7772out_unlock:
7773 mutex_unlock(&cfs_constraints_mutex);
7774
7775 return ret;
7776}
7777
7778int tg_set_cfs_quota(struct task_group *tg, long cfs_quota_us)
7779{
7780 u64 quota, period;
7781
7782 period = ktime_to_ns(tg->cfs_bandwidth.period);
7783 if (cfs_quota_us < 0)
7784 quota = RUNTIME_INF;
7785 else
7786 quota = (u64)cfs_quota_us * NSEC_PER_USEC;
7787
7788 return tg_set_cfs_bandwidth(tg, period, quota);
7789}
7790
7791long tg_get_cfs_quota(struct task_group *tg)
7792{
7793 u64 quota_us;
7794
7795 if (tg->cfs_bandwidth.quota == RUNTIME_INF)
7796 return -1;
7797
7798 quota_us = tg->cfs_bandwidth.quota;
7799 do_div(quota_us, NSEC_PER_USEC);
7800
7801 return quota_us;
7802}
7803
7804int tg_set_cfs_period(struct task_group *tg, long cfs_period_us)
7805{
7806 u64 quota, period;
7807
7808 period = (u64)cfs_period_us * NSEC_PER_USEC;
7809 quota = tg->cfs_bandwidth.quota;
7810
7811 return tg_set_cfs_bandwidth(tg, period, quota);
7812}
7813
7814long tg_get_cfs_period(struct task_group *tg)
7815{
7816 u64 cfs_period_us;
7817
7818 cfs_period_us = ktime_to_ns(tg->cfs_bandwidth.period);
7819 do_div(cfs_period_us, NSEC_PER_USEC);
7820
7821 return cfs_period_us;
7822}
7823
7824static s64 cpu_cfs_quota_read_s64(struct cgroup_subsys_state *css,
7825 struct cftype *cft)
7826{
7827 return tg_get_cfs_quota(css_tg(css));
7828}
7829
7830static int cpu_cfs_quota_write_s64(struct cgroup_subsys_state *css,
7831 struct cftype *cftype, s64 cfs_quota_us)
7832{
7833 return tg_set_cfs_quota(css_tg(css), cfs_quota_us);
7834}
7835
7836static u64 cpu_cfs_period_read_u64(struct cgroup_subsys_state *css,
7837 struct cftype *cft)
7838{
7839 return tg_get_cfs_period(css_tg(css));
7840}
7841
7842static int cpu_cfs_period_write_u64(struct cgroup_subsys_state *css,
7843 struct cftype *cftype, u64 cfs_period_us)
7844{
7845 return tg_set_cfs_period(css_tg(css), cfs_period_us);
7846}
7847
7848struct cfs_schedulable_data {
7849 struct task_group *tg;
7850 u64 period, quota;
7851};
7852
7853/*
7854 * normalize group quota/period to be quota/max_period
7855 * note: units are usecs
7856 */
7857static u64 normalize_cfs_quota(struct task_group *tg,
7858 struct cfs_schedulable_data *d)
7859{
7860 u64 quota, period;
7861
7862 if (tg == d->tg) {
7863 period = d->period;
7864 quota = d->quota;
7865 } else {
7866 period = tg_get_cfs_period(tg);
7867 quota = tg_get_cfs_quota(tg);
7868 }
7869
7870 /* note: these should typically be equivalent */
7871 if (quota == RUNTIME_INF || quota == -1)
7872 return RUNTIME_INF;
7873
7874 return to_ratio(period, quota);
7875}
7876
7877static int tg_cfs_schedulable_down(struct task_group *tg, void *data)
7878{
7879 struct cfs_schedulable_data *d = data;
7880 struct cfs_bandwidth *cfs_b = &tg->cfs_bandwidth;
7881 s64 quota = 0, parent_quota = -1;
7882
7883 if (!tg->parent) {
7884 quota = RUNTIME_INF;
7885 } else {
7886 struct cfs_bandwidth *parent_b = &tg->parent->cfs_bandwidth;
7887
7888 quota = normalize_cfs_quota(tg, d);
7889 parent_quota = parent_b->hierarchal_quota;
7890
7891 /*
7892 * ensure max(child_quota) <= parent_quota, inherit when no
7893 * limit is set
7894 */
7895 if (quota == RUNTIME_INF)
7896 quota = parent_quota;
7897 else if (parent_quota != RUNTIME_INF && quota > parent_quota)
7898 return -EINVAL;
7899 }
7900 cfs_b->hierarchal_quota = quota;
7901
7902 return 0;
7903}
7904
7905static int __cfs_schedulable(struct task_group *tg, u64 period, u64 quota)
7906{
7907 int ret;
7908 struct cfs_schedulable_data data = {
7909 .tg = tg,
7910 .period = period,
7911 .quota = quota,
7912 };
7913
7914 if (quota != RUNTIME_INF) {
7915 do_div(data.period, NSEC_PER_USEC);
7916 do_div(data.quota, NSEC_PER_USEC);
7917 }
7918
7919 rcu_read_lock();
7920 ret = walk_tg_tree(tg_cfs_schedulable_down, tg_nop, &data);
7921 rcu_read_unlock();
7922
7923 return ret;
7924}
7925
7926static int cpu_stats_show(struct seq_file *sf, void *v)
7927{
7928 struct task_group *tg = css_tg(seq_css(sf));
7929 struct cfs_bandwidth *cfs_b = &tg->cfs_bandwidth;
7930
7931 seq_printf(sf, "nr_periods %d\n", cfs_b->nr_periods);
7932 seq_printf(sf, "nr_throttled %d\n", cfs_b->nr_throttled);
7933 seq_printf(sf, "throttled_time %llu\n", cfs_b->throttled_time);
7934
7935 return 0;
7936}
7937#endif /* CONFIG_CFS_BANDWIDTH */
7938#endif /* CONFIG_FAIR_GROUP_SCHED */
7939
7940#ifdef CONFIG_RT_GROUP_SCHED
7941static int cpu_rt_runtime_write(struct cgroup_subsys_state *css,
7942 struct cftype *cft, s64 val)
7943{
7944 return sched_group_set_rt_runtime(css_tg(css), val);
7945}
7946
7947static s64 cpu_rt_runtime_read(struct cgroup_subsys_state *css,
7948 struct cftype *cft)
7949{
7950 return sched_group_rt_runtime(css_tg(css));
7951}
7952
7953static int cpu_rt_period_write_uint(struct cgroup_subsys_state *css,
7954 struct cftype *cftype, u64 rt_period_us)
7955{
7956 return sched_group_set_rt_period(css_tg(css), rt_period_us);
7957}
7958
7959static u64 cpu_rt_period_read_uint(struct cgroup_subsys_state *css,
7960 struct cftype *cft)
7961{
7962 return sched_group_rt_period(css_tg(css));
7963}
7964#endif /* CONFIG_RT_GROUP_SCHED */
7965
7966static struct cftype cpu_files[] = {
7967#ifdef CONFIG_FAIR_GROUP_SCHED
7968 {
7969 .name = "shares",
7970 .read_u64 = cpu_shares_read_u64,
7971 .write_u64 = cpu_shares_write_u64,
7972 },
7973#endif
7974#ifdef CONFIG_CFS_BANDWIDTH
7975 {
7976 .name = "cfs_quota_us",
7977 .read_s64 = cpu_cfs_quota_read_s64,
7978 .write_s64 = cpu_cfs_quota_write_s64,
7979 },
7980 {
7981 .name = "cfs_period_us",
7982 .read_u64 = cpu_cfs_period_read_u64,
7983 .write_u64 = cpu_cfs_period_write_u64,
7984 },
7985 {
7986 .name = "stat",
7987 .seq_show = cpu_stats_show,
7988 },
7989#endif
7990#ifdef CONFIG_RT_GROUP_SCHED
7991 {
7992 .name = "rt_runtime_us",
7993 .read_s64 = cpu_rt_runtime_read,
7994 .write_s64 = cpu_rt_runtime_write,
7995 },
7996 {
7997 .name = "rt_period_us",
7998 .read_u64 = cpu_rt_period_read_uint,
7999 .write_u64 = cpu_rt_period_write_uint,
8000 },
8001#endif
8002 { } /* terminate */
8003};
8004
8005struct cgroup_subsys cpu_cgrp_subsys = {
8006 .css_alloc = cpu_cgroup_css_alloc,
8007 .css_free = cpu_cgroup_css_free,
8008 .css_online = cpu_cgroup_css_online,
8009 .css_offline = cpu_cgroup_css_offline,
8010 .can_attach = cpu_cgroup_can_attach,
8011 .attach = cpu_cgroup_attach,
8012 .exit = cpu_cgroup_exit,
8013 .base_cftypes = cpu_files,
8014 .early_init = 1,
8015};
8016
8017#endif /* CONFIG_CGROUP_SCHED */
8018
8019void dump_cpu_task(int cpu)
8020{
8021 pr_info("Task dump for CPU %d:\n", cpu);
8022 sched_show_task(cpu_curr(cpu));
8023}
1/*
2 * kernel/sched/core.c
3 *
4 * Core kernel scheduler code and related syscalls
5 *
6 * Copyright (C) 1991-2002 Linus Torvalds
7 */
8#include "sched.h"
9
10#include <linux/kthread.h>
11#include <linux/nospec.h>
12
13#include <asm/switch_to.h>
14#include <asm/tlb.h>
15
16#include "../workqueue_internal.h"
17#include "../smpboot.h"
18
19#define CREATE_TRACE_POINTS
20#include <trace/events/sched.h>
21
22DEFINE_PER_CPU_SHARED_ALIGNED(struct rq, runqueues);
23
24#if defined(CONFIG_SCHED_DEBUG) && defined(HAVE_JUMP_LABEL)
25/*
26 * Debugging: various feature bits
27 *
28 * If SCHED_DEBUG is disabled, each compilation unit has its own copy of
29 * sysctl_sched_features, defined in sched.h, to allow constants propagation
30 * at compile time and compiler optimization based on features default.
31 */
32#define SCHED_FEAT(name, enabled) \
33 (1UL << __SCHED_FEAT_##name) * enabled |
34const_debug unsigned int sysctl_sched_features =
35#include "features.h"
36 0;
37#undef SCHED_FEAT
38#endif
39
40/*
41 * Number of tasks to iterate in a single balance run.
42 * Limited because this is done with IRQs disabled.
43 */
44const_debug unsigned int sysctl_sched_nr_migrate = 32;
45
46/*
47 * period over which we average the RT time consumption, measured
48 * in ms.
49 *
50 * default: 1s
51 */
52const_debug unsigned int sysctl_sched_time_avg = MSEC_PER_SEC;
53
54/*
55 * period over which we measure -rt task CPU usage in us.
56 * default: 1s
57 */
58unsigned int sysctl_sched_rt_period = 1000000;
59
60__read_mostly int scheduler_running;
61
62/*
63 * part of the period that we allow rt tasks to run in us.
64 * default: 0.95s
65 */
66int sysctl_sched_rt_runtime = 950000;
67
68/*
69 * __task_rq_lock - lock the rq @p resides on.
70 */
71struct rq *__task_rq_lock(struct task_struct *p, struct rq_flags *rf)
72 __acquires(rq->lock)
73{
74 struct rq *rq;
75
76 lockdep_assert_held(&p->pi_lock);
77
78 for (;;) {
79 rq = task_rq(p);
80 raw_spin_lock(&rq->lock);
81 if (likely(rq == task_rq(p) && !task_on_rq_migrating(p))) {
82 rq_pin_lock(rq, rf);
83 return rq;
84 }
85 raw_spin_unlock(&rq->lock);
86
87 while (unlikely(task_on_rq_migrating(p)))
88 cpu_relax();
89 }
90}
91
92/*
93 * task_rq_lock - lock p->pi_lock and lock the rq @p resides on.
94 */
95struct rq *task_rq_lock(struct task_struct *p, struct rq_flags *rf)
96 __acquires(p->pi_lock)
97 __acquires(rq->lock)
98{
99 struct rq *rq;
100
101 for (;;) {
102 raw_spin_lock_irqsave(&p->pi_lock, rf->flags);
103 rq = task_rq(p);
104 raw_spin_lock(&rq->lock);
105 /*
106 * move_queued_task() task_rq_lock()
107 *
108 * ACQUIRE (rq->lock)
109 * [S] ->on_rq = MIGRATING [L] rq = task_rq()
110 * WMB (__set_task_cpu()) ACQUIRE (rq->lock);
111 * [S] ->cpu = new_cpu [L] task_rq()
112 * [L] ->on_rq
113 * RELEASE (rq->lock)
114 *
115 * If we observe the old CPU in task_rq_lock, the acquire of
116 * the old rq->lock will fully serialize against the stores.
117 *
118 * If we observe the new CPU in task_rq_lock, the acquire will
119 * pair with the WMB to ensure we must then also see migrating.
120 */
121 if (likely(rq == task_rq(p) && !task_on_rq_migrating(p))) {
122 rq_pin_lock(rq, rf);
123 return rq;
124 }
125 raw_spin_unlock(&rq->lock);
126 raw_spin_unlock_irqrestore(&p->pi_lock, rf->flags);
127
128 while (unlikely(task_on_rq_migrating(p)))
129 cpu_relax();
130 }
131}
132
133/*
134 * RQ-clock updating methods:
135 */
136
137static void update_rq_clock_task(struct rq *rq, s64 delta)
138{
139/*
140 * In theory, the compile should just see 0 here, and optimize out the call
141 * to sched_rt_avg_update. But I don't trust it...
142 */
143#if defined(CONFIG_IRQ_TIME_ACCOUNTING) || defined(CONFIG_PARAVIRT_TIME_ACCOUNTING)
144 s64 steal = 0, irq_delta = 0;
145#endif
146#ifdef CONFIG_IRQ_TIME_ACCOUNTING
147 irq_delta = irq_time_read(cpu_of(rq)) - rq->prev_irq_time;
148
149 /*
150 * Since irq_time is only updated on {soft,}irq_exit, we might run into
151 * this case when a previous update_rq_clock() happened inside a
152 * {soft,}irq region.
153 *
154 * When this happens, we stop ->clock_task and only update the
155 * prev_irq_time stamp to account for the part that fit, so that a next
156 * update will consume the rest. This ensures ->clock_task is
157 * monotonic.
158 *
159 * It does however cause some slight miss-attribution of {soft,}irq
160 * time, a more accurate solution would be to update the irq_time using
161 * the current rq->clock timestamp, except that would require using
162 * atomic ops.
163 */
164 if (irq_delta > delta)
165 irq_delta = delta;
166
167 rq->prev_irq_time += irq_delta;
168 delta -= irq_delta;
169#endif
170#ifdef CONFIG_PARAVIRT_TIME_ACCOUNTING
171 if (static_key_false((¶virt_steal_rq_enabled))) {
172 steal = paravirt_steal_clock(cpu_of(rq));
173 steal -= rq->prev_steal_time_rq;
174
175 if (unlikely(steal > delta))
176 steal = delta;
177
178 rq->prev_steal_time_rq += steal;
179 delta -= steal;
180 }
181#endif
182
183 rq->clock_task += delta;
184
185#if defined(CONFIG_IRQ_TIME_ACCOUNTING) || defined(CONFIG_PARAVIRT_TIME_ACCOUNTING)
186 if ((irq_delta + steal) && sched_feat(NONTASK_CAPACITY))
187 sched_rt_avg_update(rq, irq_delta + steal);
188#endif
189}
190
191void update_rq_clock(struct rq *rq)
192{
193 s64 delta;
194
195 lockdep_assert_held(&rq->lock);
196
197 if (rq->clock_update_flags & RQCF_ACT_SKIP)
198 return;
199
200#ifdef CONFIG_SCHED_DEBUG
201 if (sched_feat(WARN_DOUBLE_CLOCK))
202 SCHED_WARN_ON(rq->clock_update_flags & RQCF_UPDATED);
203 rq->clock_update_flags |= RQCF_UPDATED;
204#endif
205
206 delta = sched_clock_cpu(cpu_of(rq)) - rq->clock;
207 if (delta < 0)
208 return;
209 rq->clock += delta;
210 update_rq_clock_task(rq, delta);
211}
212
213
214#ifdef CONFIG_SCHED_HRTICK
215/*
216 * Use HR-timers to deliver accurate preemption points.
217 */
218
219static void hrtick_clear(struct rq *rq)
220{
221 if (hrtimer_active(&rq->hrtick_timer))
222 hrtimer_cancel(&rq->hrtick_timer);
223}
224
225/*
226 * High-resolution timer tick.
227 * Runs from hardirq context with interrupts disabled.
228 */
229static enum hrtimer_restart hrtick(struct hrtimer *timer)
230{
231 struct rq *rq = container_of(timer, struct rq, hrtick_timer);
232 struct rq_flags rf;
233
234 WARN_ON_ONCE(cpu_of(rq) != smp_processor_id());
235
236 rq_lock(rq, &rf);
237 update_rq_clock(rq);
238 rq->curr->sched_class->task_tick(rq, rq->curr, 1);
239 rq_unlock(rq, &rf);
240
241 return HRTIMER_NORESTART;
242}
243
244#ifdef CONFIG_SMP
245
246static void __hrtick_restart(struct rq *rq)
247{
248 struct hrtimer *timer = &rq->hrtick_timer;
249
250 hrtimer_start_expires(timer, HRTIMER_MODE_ABS_PINNED);
251}
252
253/*
254 * called from hardirq (IPI) context
255 */
256static void __hrtick_start(void *arg)
257{
258 struct rq *rq = arg;
259 struct rq_flags rf;
260
261 rq_lock(rq, &rf);
262 __hrtick_restart(rq);
263 rq->hrtick_csd_pending = 0;
264 rq_unlock(rq, &rf);
265}
266
267/*
268 * Called to set the hrtick timer state.
269 *
270 * called with rq->lock held and irqs disabled
271 */
272void hrtick_start(struct rq *rq, u64 delay)
273{
274 struct hrtimer *timer = &rq->hrtick_timer;
275 ktime_t time;
276 s64 delta;
277
278 /*
279 * Don't schedule slices shorter than 10000ns, that just
280 * doesn't make sense and can cause timer DoS.
281 */
282 delta = max_t(s64, delay, 10000LL);
283 time = ktime_add_ns(timer->base->get_time(), delta);
284
285 hrtimer_set_expires(timer, time);
286
287 if (rq == this_rq()) {
288 __hrtick_restart(rq);
289 } else if (!rq->hrtick_csd_pending) {
290 smp_call_function_single_async(cpu_of(rq), &rq->hrtick_csd);
291 rq->hrtick_csd_pending = 1;
292 }
293}
294
295#else
296/*
297 * Called to set the hrtick timer state.
298 *
299 * called with rq->lock held and irqs disabled
300 */
301void hrtick_start(struct rq *rq, u64 delay)
302{
303 /*
304 * Don't schedule slices shorter than 10000ns, that just
305 * doesn't make sense. Rely on vruntime for fairness.
306 */
307 delay = max_t(u64, delay, 10000LL);
308 hrtimer_start(&rq->hrtick_timer, ns_to_ktime(delay),
309 HRTIMER_MODE_REL_PINNED);
310}
311#endif /* CONFIG_SMP */
312
313static void hrtick_rq_init(struct rq *rq)
314{
315#ifdef CONFIG_SMP
316 rq->hrtick_csd_pending = 0;
317
318 rq->hrtick_csd.flags = 0;
319 rq->hrtick_csd.func = __hrtick_start;
320 rq->hrtick_csd.info = rq;
321#endif
322
323 hrtimer_init(&rq->hrtick_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
324 rq->hrtick_timer.function = hrtick;
325}
326#else /* CONFIG_SCHED_HRTICK */
327static inline void hrtick_clear(struct rq *rq)
328{
329}
330
331static inline void hrtick_rq_init(struct rq *rq)
332{
333}
334#endif /* CONFIG_SCHED_HRTICK */
335
336/*
337 * cmpxchg based fetch_or, macro so it works for different integer types
338 */
339#define fetch_or(ptr, mask) \
340 ({ \
341 typeof(ptr) _ptr = (ptr); \
342 typeof(mask) _mask = (mask); \
343 typeof(*_ptr) _old, _val = *_ptr; \
344 \
345 for (;;) { \
346 _old = cmpxchg(_ptr, _val, _val | _mask); \
347 if (_old == _val) \
348 break; \
349 _val = _old; \
350 } \
351 _old; \
352})
353
354#if defined(CONFIG_SMP) && defined(TIF_POLLING_NRFLAG)
355/*
356 * Atomically set TIF_NEED_RESCHED and test for TIF_POLLING_NRFLAG,
357 * this avoids any races wrt polling state changes and thereby avoids
358 * spurious IPIs.
359 */
360static bool set_nr_and_not_polling(struct task_struct *p)
361{
362 struct thread_info *ti = task_thread_info(p);
363 return !(fetch_or(&ti->flags, _TIF_NEED_RESCHED) & _TIF_POLLING_NRFLAG);
364}
365
366/*
367 * Atomically set TIF_NEED_RESCHED if TIF_POLLING_NRFLAG is set.
368 *
369 * If this returns true, then the idle task promises to call
370 * sched_ttwu_pending() and reschedule soon.
371 */
372static bool set_nr_if_polling(struct task_struct *p)
373{
374 struct thread_info *ti = task_thread_info(p);
375 typeof(ti->flags) old, val = READ_ONCE(ti->flags);
376
377 for (;;) {
378 if (!(val & _TIF_POLLING_NRFLAG))
379 return false;
380 if (val & _TIF_NEED_RESCHED)
381 return true;
382 old = cmpxchg(&ti->flags, val, val | _TIF_NEED_RESCHED);
383 if (old == val)
384 break;
385 val = old;
386 }
387 return true;
388}
389
390#else
391static bool set_nr_and_not_polling(struct task_struct *p)
392{
393 set_tsk_need_resched(p);
394 return true;
395}
396
397#ifdef CONFIG_SMP
398static bool set_nr_if_polling(struct task_struct *p)
399{
400 return false;
401}
402#endif
403#endif
404
405void wake_q_add(struct wake_q_head *head, struct task_struct *task)
406{
407 struct wake_q_node *node = &task->wake_q;
408
409 /*
410 * Atomically grab the task, if ->wake_q is !nil already it means
411 * its already queued (either by us or someone else) and will get the
412 * wakeup due to that.
413 *
414 * This cmpxchg() implies a full barrier, which pairs with the write
415 * barrier implied by the wakeup in wake_up_q().
416 */
417 if (cmpxchg(&node->next, NULL, WAKE_Q_TAIL))
418 return;
419
420 get_task_struct(task);
421
422 /*
423 * The head is context local, there can be no concurrency.
424 */
425 *head->lastp = node;
426 head->lastp = &node->next;
427}
428
429void wake_up_q(struct wake_q_head *head)
430{
431 struct wake_q_node *node = head->first;
432
433 while (node != WAKE_Q_TAIL) {
434 struct task_struct *task;
435
436 task = container_of(node, struct task_struct, wake_q);
437 BUG_ON(!task);
438 /* Task can safely be re-inserted now: */
439 node = node->next;
440 task->wake_q.next = NULL;
441
442 /*
443 * wake_up_process() implies a wmb() to pair with the queueing
444 * in wake_q_add() so as not to miss wakeups.
445 */
446 wake_up_process(task);
447 put_task_struct(task);
448 }
449}
450
451/*
452 * resched_curr - mark rq's current task 'to be rescheduled now'.
453 *
454 * On UP this means the setting of the need_resched flag, on SMP it
455 * might also involve a cross-CPU call to trigger the scheduler on
456 * the target CPU.
457 */
458void resched_curr(struct rq *rq)
459{
460 struct task_struct *curr = rq->curr;
461 int cpu;
462
463 lockdep_assert_held(&rq->lock);
464
465 if (test_tsk_need_resched(curr))
466 return;
467
468 cpu = cpu_of(rq);
469
470 if (cpu == smp_processor_id()) {
471 set_tsk_need_resched(curr);
472 set_preempt_need_resched();
473 return;
474 }
475
476 if (set_nr_and_not_polling(curr))
477 smp_send_reschedule(cpu);
478 else
479 trace_sched_wake_idle_without_ipi(cpu);
480}
481
482void resched_cpu(int cpu)
483{
484 struct rq *rq = cpu_rq(cpu);
485 unsigned long flags;
486
487 raw_spin_lock_irqsave(&rq->lock, flags);
488 if (cpu_online(cpu) || cpu == smp_processor_id())
489 resched_curr(rq);
490 raw_spin_unlock_irqrestore(&rq->lock, flags);
491}
492
493#ifdef CONFIG_SMP
494#ifdef CONFIG_NO_HZ_COMMON
495/*
496 * In the semi idle case, use the nearest busy CPU for migrating timers
497 * from an idle CPU. This is good for power-savings.
498 *
499 * We don't do similar optimization for completely idle system, as
500 * selecting an idle CPU will add more delays to the timers than intended
501 * (as that CPU's timer base may not be uptodate wrt jiffies etc).
502 */
503int get_nohz_timer_target(void)
504{
505 int i, cpu = smp_processor_id();
506 struct sched_domain *sd;
507
508 if (!idle_cpu(cpu) && housekeeping_cpu(cpu, HK_FLAG_TIMER))
509 return cpu;
510
511 rcu_read_lock();
512 for_each_domain(cpu, sd) {
513 for_each_cpu(i, sched_domain_span(sd)) {
514 if (cpu == i)
515 continue;
516
517 if (!idle_cpu(i) && housekeeping_cpu(i, HK_FLAG_TIMER)) {
518 cpu = i;
519 goto unlock;
520 }
521 }
522 }
523
524 if (!housekeeping_cpu(cpu, HK_FLAG_TIMER))
525 cpu = housekeeping_any_cpu(HK_FLAG_TIMER);
526unlock:
527 rcu_read_unlock();
528 return cpu;
529}
530
531/*
532 * When add_timer_on() enqueues a timer into the timer wheel of an
533 * idle CPU then this timer might expire before the next timer event
534 * which is scheduled to wake up that CPU. In case of a completely
535 * idle system the next event might even be infinite time into the
536 * future. wake_up_idle_cpu() ensures that the CPU is woken up and
537 * leaves the inner idle loop so the newly added timer is taken into
538 * account when the CPU goes back to idle and evaluates the timer
539 * wheel for the next timer event.
540 */
541static void wake_up_idle_cpu(int cpu)
542{
543 struct rq *rq = cpu_rq(cpu);
544
545 if (cpu == smp_processor_id())
546 return;
547
548 if (set_nr_and_not_polling(rq->idle))
549 smp_send_reschedule(cpu);
550 else
551 trace_sched_wake_idle_without_ipi(cpu);
552}
553
554static bool wake_up_full_nohz_cpu(int cpu)
555{
556 /*
557 * We just need the target to call irq_exit() and re-evaluate
558 * the next tick. The nohz full kick at least implies that.
559 * If needed we can still optimize that later with an
560 * empty IRQ.
561 */
562 if (cpu_is_offline(cpu))
563 return true; /* Don't try to wake offline CPUs. */
564 if (tick_nohz_full_cpu(cpu)) {
565 if (cpu != smp_processor_id() ||
566 tick_nohz_tick_stopped())
567 tick_nohz_full_kick_cpu(cpu);
568 return true;
569 }
570
571 return false;
572}
573
574/*
575 * Wake up the specified CPU. If the CPU is going offline, it is the
576 * caller's responsibility to deal with the lost wakeup, for example,
577 * by hooking into the CPU_DEAD notifier like timers and hrtimers do.
578 */
579void wake_up_nohz_cpu(int cpu)
580{
581 if (!wake_up_full_nohz_cpu(cpu))
582 wake_up_idle_cpu(cpu);
583}
584
585static inline bool got_nohz_idle_kick(void)
586{
587 int cpu = smp_processor_id();
588
589 if (!(atomic_read(nohz_flags(cpu)) & NOHZ_KICK_MASK))
590 return false;
591
592 if (idle_cpu(cpu) && !need_resched())
593 return true;
594
595 /*
596 * We can't run Idle Load Balance on this CPU for this time so we
597 * cancel it and clear NOHZ_BALANCE_KICK
598 */
599 atomic_andnot(NOHZ_KICK_MASK, nohz_flags(cpu));
600 return false;
601}
602
603#else /* CONFIG_NO_HZ_COMMON */
604
605static inline bool got_nohz_idle_kick(void)
606{
607 return false;
608}
609
610#endif /* CONFIG_NO_HZ_COMMON */
611
612#ifdef CONFIG_NO_HZ_FULL
613bool sched_can_stop_tick(struct rq *rq)
614{
615 int fifo_nr_running;
616
617 /* Deadline tasks, even if single, need the tick */
618 if (rq->dl.dl_nr_running)
619 return false;
620
621 /*
622 * If there are more than one RR tasks, we need the tick to effect the
623 * actual RR behaviour.
624 */
625 if (rq->rt.rr_nr_running) {
626 if (rq->rt.rr_nr_running == 1)
627 return true;
628 else
629 return false;
630 }
631
632 /*
633 * If there's no RR tasks, but FIFO tasks, we can skip the tick, no
634 * forced preemption between FIFO tasks.
635 */
636 fifo_nr_running = rq->rt.rt_nr_running - rq->rt.rr_nr_running;
637 if (fifo_nr_running)
638 return true;
639
640 /*
641 * If there are no DL,RR/FIFO tasks, there must only be CFS tasks left;
642 * if there's more than one we need the tick for involuntary
643 * preemption.
644 */
645 if (rq->nr_running > 1)
646 return false;
647
648 return true;
649}
650#endif /* CONFIG_NO_HZ_FULL */
651
652void sched_avg_update(struct rq *rq)
653{
654 s64 period = sched_avg_period();
655
656 while ((s64)(rq_clock(rq) - rq->age_stamp) > period) {
657 /*
658 * Inline assembly required to prevent the compiler
659 * optimising this loop into a divmod call.
660 * See __iter_div_u64_rem() for another example of this.
661 */
662 asm("" : "+rm" (rq->age_stamp));
663 rq->age_stamp += period;
664 rq->rt_avg /= 2;
665 }
666}
667
668#endif /* CONFIG_SMP */
669
670#if defined(CONFIG_RT_GROUP_SCHED) || (defined(CONFIG_FAIR_GROUP_SCHED) && \
671 (defined(CONFIG_SMP) || defined(CONFIG_CFS_BANDWIDTH)))
672/*
673 * Iterate task_group tree rooted at *from, calling @down when first entering a
674 * node and @up when leaving it for the final time.
675 *
676 * Caller must hold rcu_lock or sufficient equivalent.
677 */
678int walk_tg_tree_from(struct task_group *from,
679 tg_visitor down, tg_visitor up, void *data)
680{
681 struct task_group *parent, *child;
682 int ret;
683
684 parent = from;
685
686down:
687 ret = (*down)(parent, data);
688 if (ret)
689 goto out;
690 list_for_each_entry_rcu(child, &parent->children, siblings) {
691 parent = child;
692 goto down;
693
694up:
695 continue;
696 }
697 ret = (*up)(parent, data);
698 if (ret || parent == from)
699 goto out;
700
701 child = parent;
702 parent = parent->parent;
703 if (parent)
704 goto up;
705out:
706 return ret;
707}
708
709int tg_nop(struct task_group *tg, void *data)
710{
711 return 0;
712}
713#endif
714
715static void set_load_weight(struct task_struct *p, bool update_load)
716{
717 int prio = p->static_prio - MAX_RT_PRIO;
718 struct load_weight *load = &p->se.load;
719
720 /*
721 * SCHED_IDLE tasks get minimal weight:
722 */
723 if (idle_policy(p->policy)) {
724 load->weight = scale_load(WEIGHT_IDLEPRIO);
725 load->inv_weight = WMULT_IDLEPRIO;
726 return;
727 }
728
729 /*
730 * SCHED_OTHER tasks have to update their load when changing their
731 * weight
732 */
733 if (update_load && p->sched_class == &fair_sched_class) {
734 reweight_task(p, prio);
735 } else {
736 load->weight = scale_load(sched_prio_to_weight[prio]);
737 load->inv_weight = sched_prio_to_wmult[prio];
738 }
739}
740
741static inline void enqueue_task(struct rq *rq, struct task_struct *p, int flags)
742{
743 if (!(flags & ENQUEUE_NOCLOCK))
744 update_rq_clock(rq);
745
746 if (!(flags & ENQUEUE_RESTORE))
747 sched_info_queued(rq, p);
748
749 p->sched_class->enqueue_task(rq, p, flags);
750}
751
752static inline void dequeue_task(struct rq *rq, struct task_struct *p, int flags)
753{
754 if (!(flags & DEQUEUE_NOCLOCK))
755 update_rq_clock(rq);
756
757 if (!(flags & DEQUEUE_SAVE))
758 sched_info_dequeued(rq, p);
759
760 p->sched_class->dequeue_task(rq, p, flags);
761}
762
763void activate_task(struct rq *rq, struct task_struct *p, int flags)
764{
765 if (task_contributes_to_load(p))
766 rq->nr_uninterruptible--;
767
768 enqueue_task(rq, p, flags);
769}
770
771void deactivate_task(struct rq *rq, struct task_struct *p, int flags)
772{
773 if (task_contributes_to_load(p))
774 rq->nr_uninterruptible++;
775
776 dequeue_task(rq, p, flags);
777}
778
779/*
780 * __normal_prio - return the priority that is based on the static prio
781 */
782static inline int __normal_prio(struct task_struct *p)
783{
784 return p->static_prio;
785}
786
787/*
788 * Calculate the expected normal priority: i.e. priority
789 * without taking RT-inheritance into account. Might be
790 * boosted by interactivity modifiers. Changes upon fork,
791 * setprio syscalls, and whenever the interactivity
792 * estimator recalculates.
793 */
794static inline int normal_prio(struct task_struct *p)
795{
796 int prio;
797
798 if (task_has_dl_policy(p))
799 prio = MAX_DL_PRIO-1;
800 else if (task_has_rt_policy(p))
801 prio = MAX_RT_PRIO-1 - p->rt_priority;
802 else
803 prio = __normal_prio(p);
804 return prio;
805}
806
807/*
808 * Calculate the current priority, i.e. the priority
809 * taken into account by the scheduler. This value might
810 * be boosted by RT tasks, or might be boosted by
811 * interactivity modifiers. Will be RT if the task got
812 * RT-boosted. If not then it returns p->normal_prio.
813 */
814static int effective_prio(struct task_struct *p)
815{
816 p->normal_prio = normal_prio(p);
817 /*
818 * If we are RT tasks or we were boosted to RT priority,
819 * keep the priority unchanged. Otherwise, update priority
820 * to the normal priority:
821 */
822 if (!rt_prio(p->prio))
823 return p->normal_prio;
824 return p->prio;
825}
826
827/**
828 * task_curr - is this task currently executing on a CPU?
829 * @p: the task in question.
830 *
831 * Return: 1 if the task is currently executing. 0 otherwise.
832 */
833inline int task_curr(const struct task_struct *p)
834{
835 return cpu_curr(task_cpu(p)) == p;
836}
837
838/*
839 * switched_from, switched_to and prio_changed must _NOT_ drop rq->lock,
840 * use the balance_callback list if you want balancing.
841 *
842 * this means any call to check_class_changed() must be followed by a call to
843 * balance_callback().
844 */
845static inline void check_class_changed(struct rq *rq, struct task_struct *p,
846 const struct sched_class *prev_class,
847 int oldprio)
848{
849 if (prev_class != p->sched_class) {
850 if (prev_class->switched_from)
851 prev_class->switched_from(rq, p);
852
853 p->sched_class->switched_to(rq, p);
854 } else if (oldprio != p->prio || dl_task(p))
855 p->sched_class->prio_changed(rq, p, oldprio);
856}
857
858void check_preempt_curr(struct rq *rq, struct task_struct *p, int flags)
859{
860 const struct sched_class *class;
861
862 if (p->sched_class == rq->curr->sched_class) {
863 rq->curr->sched_class->check_preempt_curr(rq, p, flags);
864 } else {
865 for_each_class(class) {
866 if (class == rq->curr->sched_class)
867 break;
868 if (class == p->sched_class) {
869 resched_curr(rq);
870 break;
871 }
872 }
873 }
874
875 /*
876 * A queue event has occurred, and we're going to schedule. In
877 * this case, we can save a useless back to back clock update.
878 */
879 if (task_on_rq_queued(rq->curr) && test_tsk_need_resched(rq->curr))
880 rq_clock_skip_update(rq);
881}
882
883#ifdef CONFIG_SMP
884
885static inline bool is_per_cpu_kthread(struct task_struct *p)
886{
887 if (!(p->flags & PF_KTHREAD))
888 return false;
889
890 if (p->nr_cpus_allowed != 1)
891 return false;
892
893 return true;
894}
895
896/*
897 * Per-CPU kthreads are allowed to run on !actie && online CPUs, see
898 * __set_cpus_allowed_ptr() and select_fallback_rq().
899 */
900static inline bool is_cpu_allowed(struct task_struct *p, int cpu)
901{
902 if (!cpumask_test_cpu(cpu, &p->cpus_allowed))
903 return false;
904
905 if (is_per_cpu_kthread(p))
906 return cpu_online(cpu);
907
908 return cpu_active(cpu);
909}
910
911/*
912 * This is how migration works:
913 *
914 * 1) we invoke migration_cpu_stop() on the target CPU using
915 * stop_one_cpu().
916 * 2) stopper starts to run (implicitly forcing the migrated thread
917 * off the CPU)
918 * 3) it checks whether the migrated task is still in the wrong runqueue.
919 * 4) if it's in the wrong runqueue then the migration thread removes
920 * it and puts it into the right queue.
921 * 5) stopper completes and stop_one_cpu() returns and the migration
922 * is done.
923 */
924
925/*
926 * move_queued_task - move a queued task to new rq.
927 *
928 * Returns (locked) new rq. Old rq's lock is released.
929 */
930static struct rq *move_queued_task(struct rq *rq, struct rq_flags *rf,
931 struct task_struct *p, int new_cpu)
932{
933 lockdep_assert_held(&rq->lock);
934
935 p->on_rq = TASK_ON_RQ_MIGRATING;
936 dequeue_task(rq, p, DEQUEUE_NOCLOCK);
937 set_task_cpu(p, new_cpu);
938 rq_unlock(rq, rf);
939
940 rq = cpu_rq(new_cpu);
941
942 rq_lock(rq, rf);
943 BUG_ON(task_cpu(p) != new_cpu);
944 enqueue_task(rq, p, 0);
945 p->on_rq = TASK_ON_RQ_QUEUED;
946 check_preempt_curr(rq, p, 0);
947
948 return rq;
949}
950
951struct migration_arg {
952 struct task_struct *task;
953 int dest_cpu;
954};
955
956/*
957 * Move (not current) task off this CPU, onto the destination CPU. We're doing
958 * this because either it can't run here any more (set_cpus_allowed()
959 * away from this CPU, or CPU going down), or because we're
960 * attempting to rebalance this task on exec (sched_exec).
961 *
962 * So we race with normal scheduler movements, but that's OK, as long
963 * as the task is no longer on this CPU.
964 */
965static struct rq *__migrate_task(struct rq *rq, struct rq_flags *rf,
966 struct task_struct *p, int dest_cpu)
967{
968 /* Affinity changed (again). */
969 if (!is_cpu_allowed(p, dest_cpu))
970 return rq;
971
972 update_rq_clock(rq);
973 rq = move_queued_task(rq, rf, p, dest_cpu);
974
975 return rq;
976}
977
978/*
979 * migration_cpu_stop - this will be executed by a highprio stopper thread
980 * and performs thread migration by bumping thread off CPU then
981 * 'pushing' onto another runqueue.
982 */
983static int migration_cpu_stop(void *data)
984{
985 struct migration_arg *arg = data;
986 struct task_struct *p = arg->task;
987 struct rq *rq = this_rq();
988 struct rq_flags rf;
989
990 /*
991 * The original target CPU might have gone down and we might
992 * be on another CPU but it doesn't matter.
993 */
994 local_irq_disable();
995 /*
996 * We need to explicitly wake pending tasks before running
997 * __migrate_task() such that we will not miss enforcing cpus_allowed
998 * during wakeups, see set_cpus_allowed_ptr()'s TASK_WAKING test.
999 */
1000 sched_ttwu_pending();
1001
1002 raw_spin_lock(&p->pi_lock);
1003 rq_lock(rq, &rf);
1004 /*
1005 * If task_rq(p) != rq, it cannot be migrated here, because we're
1006 * holding rq->lock, if p->on_rq == 0 it cannot get enqueued because
1007 * we're holding p->pi_lock.
1008 */
1009 if (task_rq(p) == rq) {
1010 if (task_on_rq_queued(p))
1011 rq = __migrate_task(rq, &rf, p, arg->dest_cpu);
1012 else
1013 p->wake_cpu = arg->dest_cpu;
1014 }
1015 rq_unlock(rq, &rf);
1016 raw_spin_unlock(&p->pi_lock);
1017
1018 local_irq_enable();
1019 return 0;
1020}
1021
1022/*
1023 * sched_class::set_cpus_allowed must do the below, but is not required to
1024 * actually call this function.
1025 */
1026void set_cpus_allowed_common(struct task_struct *p, const struct cpumask *new_mask)
1027{
1028 cpumask_copy(&p->cpus_allowed, new_mask);
1029 p->nr_cpus_allowed = cpumask_weight(new_mask);
1030}
1031
1032void do_set_cpus_allowed(struct task_struct *p, const struct cpumask *new_mask)
1033{
1034 struct rq *rq = task_rq(p);
1035 bool queued, running;
1036
1037 lockdep_assert_held(&p->pi_lock);
1038
1039 queued = task_on_rq_queued(p);
1040 running = task_current(rq, p);
1041
1042 if (queued) {
1043 /*
1044 * Because __kthread_bind() calls this on blocked tasks without
1045 * holding rq->lock.
1046 */
1047 lockdep_assert_held(&rq->lock);
1048 dequeue_task(rq, p, DEQUEUE_SAVE | DEQUEUE_NOCLOCK);
1049 }
1050 if (running)
1051 put_prev_task(rq, p);
1052
1053 p->sched_class->set_cpus_allowed(p, new_mask);
1054
1055 if (queued)
1056 enqueue_task(rq, p, ENQUEUE_RESTORE | ENQUEUE_NOCLOCK);
1057 if (running)
1058 set_curr_task(rq, p);
1059}
1060
1061/*
1062 * Change a given task's CPU affinity. Migrate the thread to a
1063 * proper CPU and schedule it away if the CPU it's executing on
1064 * is removed from the allowed bitmask.
1065 *
1066 * NOTE: the caller must have a valid reference to the task, the
1067 * task must not exit() & deallocate itself prematurely. The
1068 * call is not atomic; no spinlocks may be held.
1069 */
1070static int __set_cpus_allowed_ptr(struct task_struct *p,
1071 const struct cpumask *new_mask, bool check)
1072{
1073 const struct cpumask *cpu_valid_mask = cpu_active_mask;
1074 unsigned int dest_cpu;
1075 struct rq_flags rf;
1076 struct rq *rq;
1077 int ret = 0;
1078
1079 rq = task_rq_lock(p, &rf);
1080 update_rq_clock(rq);
1081
1082 if (p->flags & PF_KTHREAD) {
1083 /*
1084 * Kernel threads are allowed on online && !active CPUs
1085 */
1086 cpu_valid_mask = cpu_online_mask;
1087 }
1088
1089 /*
1090 * Must re-check here, to close a race against __kthread_bind(),
1091 * sched_setaffinity() is not guaranteed to observe the flag.
1092 */
1093 if (check && (p->flags & PF_NO_SETAFFINITY)) {
1094 ret = -EINVAL;
1095 goto out;
1096 }
1097
1098 if (cpumask_equal(&p->cpus_allowed, new_mask))
1099 goto out;
1100
1101 if (!cpumask_intersects(new_mask, cpu_valid_mask)) {
1102 ret = -EINVAL;
1103 goto out;
1104 }
1105
1106 do_set_cpus_allowed(p, new_mask);
1107
1108 if (p->flags & PF_KTHREAD) {
1109 /*
1110 * For kernel threads that do indeed end up on online &&
1111 * !active we want to ensure they are strict per-CPU threads.
1112 */
1113 WARN_ON(cpumask_intersects(new_mask, cpu_online_mask) &&
1114 !cpumask_intersects(new_mask, cpu_active_mask) &&
1115 p->nr_cpus_allowed != 1);
1116 }
1117
1118 /* Can the task run on the task's current CPU? If so, we're done */
1119 if (cpumask_test_cpu(task_cpu(p), new_mask))
1120 goto out;
1121
1122 dest_cpu = cpumask_any_and(cpu_valid_mask, new_mask);
1123 if (task_running(rq, p) || p->state == TASK_WAKING) {
1124 struct migration_arg arg = { p, dest_cpu };
1125 /* Need help from migration thread: drop lock and wait. */
1126 task_rq_unlock(rq, p, &rf);
1127 stop_one_cpu(cpu_of(rq), migration_cpu_stop, &arg);
1128 tlb_migrate_finish(p->mm);
1129 return 0;
1130 } else if (task_on_rq_queued(p)) {
1131 /*
1132 * OK, since we're going to drop the lock immediately
1133 * afterwards anyway.
1134 */
1135 rq = move_queued_task(rq, &rf, p, dest_cpu);
1136 }
1137out:
1138 task_rq_unlock(rq, p, &rf);
1139
1140 return ret;
1141}
1142
1143int set_cpus_allowed_ptr(struct task_struct *p, const struct cpumask *new_mask)
1144{
1145 return __set_cpus_allowed_ptr(p, new_mask, false);
1146}
1147EXPORT_SYMBOL_GPL(set_cpus_allowed_ptr);
1148
1149void set_task_cpu(struct task_struct *p, unsigned int new_cpu)
1150{
1151#ifdef CONFIG_SCHED_DEBUG
1152 /*
1153 * We should never call set_task_cpu() on a blocked task,
1154 * ttwu() will sort out the placement.
1155 */
1156 WARN_ON_ONCE(p->state != TASK_RUNNING && p->state != TASK_WAKING &&
1157 !p->on_rq);
1158
1159 /*
1160 * Migrating fair class task must have p->on_rq = TASK_ON_RQ_MIGRATING,
1161 * because schedstat_wait_{start,end} rebase migrating task's wait_start
1162 * time relying on p->on_rq.
1163 */
1164 WARN_ON_ONCE(p->state == TASK_RUNNING &&
1165 p->sched_class == &fair_sched_class &&
1166 (p->on_rq && !task_on_rq_migrating(p)));
1167
1168#ifdef CONFIG_LOCKDEP
1169 /*
1170 * The caller should hold either p->pi_lock or rq->lock, when changing
1171 * a task's CPU. ->pi_lock for waking tasks, rq->lock for runnable tasks.
1172 *
1173 * sched_move_task() holds both and thus holding either pins the cgroup,
1174 * see task_group().
1175 *
1176 * Furthermore, all task_rq users should acquire both locks, see
1177 * task_rq_lock().
1178 */
1179 WARN_ON_ONCE(debug_locks && !(lockdep_is_held(&p->pi_lock) ||
1180 lockdep_is_held(&task_rq(p)->lock)));
1181#endif
1182 /*
1183 * Clearly, migrating tasks to offline CPUs is a fairly daft thing.
1184 */
1185 WARN_ON_ONCE(!cpu_online(new_cpu));
1186#endif
1187
1188 trace_sched_migrate_task(p, new_cpu);
1189
1190 if (task_cpu(p) != new_cpu) {
1191 if (p->sched_class->migrate_task_rq)
1192 p->sched_class->migrate_task_rq(p);
1193 p->se.nr_migrations++;
1194 perf_event_task_migrate(p);
1195 }
1196
1197 __set_task_cpu(p, new_cpu);
1198}
1199
1200static void __migrate_swap_task(struct task_struct *p, int cpu)
1201{
1202 if (task_on_rq_queued(p)) {
1203 struct rq *src_rq, *dst_rq;
1204 struct rq_flags srf, drf;
1205
1206 src_rq = task_rq(p);
1207 dst_rq = cpu_rq(cpu);
1208
1209 rq_pin_lock(src_rq, &srf);
1210 rq_pin_lock(dst_rq, &drf);
1211
1212 p->on_rq = TASK_ON_RQ_MIGRATING;
1213 deactivate_task(src_rq, p, 0);
1214 set_task_cpu(p, cpu);
1215 activate_task(dst_rq, p, 0);
1216 p->on_rq = TASK_ON_RQ_QUEUED;
1217 check_preempt_curr(dst_rq, p, 0);
1218
1219 rq_unpin_lock(dst_rq, &drf);
1220 rq_unpin_lock(src_rq, &srf);
1221
1222 } else {
1223 /*
1224 * Task isn't running anymore; make it appear like we migrated
1225 * it before it went to sleep. This means on wakeup we make the
1226 * previous CPU our target instead of where it really is.
1227 */
1228 p->wake_cpu = cpu;
1229 }
1230}
1231
1232struct migration_swap_arg {
1233 struct task_struct *src_task, *dst_task;
1234 int src_cpu, dst_cpu;
1235};
1236
1237static int migrate_swap_stop(void *data)
1238{
1239 struct migration_swap_arg *arg = data;
1240 struct rq *src_rq, *dst_rq;
1241 int ret = -EAGAIN;
1242
1243 if (!cpu_active(arg->src_cpu) || !cpu_active(arg->dst_cpu))
1244 return -EAGAIN;
1245
1246 src_rq = cpu_rq(arg->src_cpu);
1247 dst_rq = cpu_rq(arg->dst_cpu);
1248
1249 double_raw_lock(&arg->src_task->pi_lock,
1250 &arg->dst_task->pi_lock);
1251 double_rq_lock(src_rq, dst_rq);
1252
1253 if (task_cpu(arg->dst_task) != arg->dst_cpu)
1254 goto unlock;
1255
1256 if (task_cpu(arg->src_task) != arg->src_cpu)
1257 goto unlock;
1258
1259 if (!cpumask_test_cpu(arg->dst_cpu, &arg->src_task->cpus_allowed))
1260 goto unlock;
1261
1262 if (!cpumask_test_cpu(arg->src_cpu, &arg->dst_task->cpus_allowed))
1263 goto unlock;
1264
1265 __migrate_swap_task(arg->src_task, arg->dst_cpu);
1266 __migrate_swap_task(arg->dst_task, arg->src_cpu);
1267
1268 ret = 0;
1269
1270unlock:
1271 double_rq_unlock(src_rq, dst_rq);
1272 raw_spin_unlock(&arg->dst_task->pi_lock);
1273 raw_spin_unlock(&arg->src_task->pi_lock);
1274
1275 return ret;
1276}
1277
1278/*
1279 * Cross migrate two tasks
1280 */
1281int migrate_swap(struct task_struct *cur, struct task_struct *p)
1282{
1283 struct migration_swap_arg arg;
1284 int ret = -EINVAL;
1285
1286 arg = (struct migration_swap_arg){
1287 .src_task = cur,
1288 .src_cpu = task_cpu(cur),
1289 .dst_task = p,
1290 .dst_cpu = task_cpu(p),
1291 };
1292
1293 if (arg.src_cpu == arg.dst_cpu)
1294 goto out;
1295
1296 /*
1297 * These three tests are all lockless; this is OK since all of them
1298 * will be re-checked with proper locks held further down the line.
1299 */
1300 if (!cpu_active(arg.src_cpu) || !cpu_active(arg.dst_cpu))
1301 goto out;
1302
1303 if (!cpumask_test_cpu(arg.dst_cpu, &arg.src_task->cpus_allowed))
1304 goto out;
1305
1306 if (!cpumask_test_cpu(arg.src_cpu, &arg.dst_task->cpus_allowed))
1307 goto out;
1308
1309 trace_sched_swap_numa(cur, arg.src_cpu, p, arg.dst_cpu);
1310 ret = stop_two_cpus(arg.dst_cpu, arg.src_cpu, migrate_swap_stop, &arg);
1311
1312out:
1313 return ret;
1314}
1315
1316/*
1317 * wait_task_inactive - wait for a thread to unschedule.
1318 *
1319 * If @match_state is nonzero, it's the @p->state value just checked and
1320 * not expected to change. If it changes, i.e. @p might have woken up,
1321 * then return zero. When we succeed in waiting for @p to be off its CPU,
1322 * we return a positive number (its total switch count). If a second call
1323 * a short while later returns the same number, the caller can be sure that
1324 * @p has remained unscheduled the whole time.
1325 *
1326 * The caller must ensure that the task *will* unschedule sometime soon,
1327 * else this function might spin for a *long* time. This function can't
1328 * be called with interrupts off, or it may introduce deadlock with
1329 * smp_call_function() if an IPI is sent by the same process we are
1330 * waiting to become inactive.
1331 */
1332unsigned long wait_task_inactive(struct task_struct *p, long match_state)
1333{
1334 int running, queued;
1335 struct rq_flags rf;
1336 unsigned long ncsw;
1337 struct rq *rq;
1338
1339 for (;;) {
1340 /*
1341 * We do the initial early heuristics without holding
1342 * any task-queue locks at all. We'll only try to get
1343 * the runqueue lock when things look like they will
1344 * work out!
1345 */
1346 rq = task_rq(p);
1347
1348 /*
1349 * If the task is actively running on another CPU
1350 * still, just relax and busy-wait without holding
1351 * any locks.
1352 *
1353 * NOTE! Since we don't hold any locks, it's not
1354 * even sure that "rq" stays as the right runqueue!
1355 * But we don't care, since "task_running()" will
1356 * return false if the runqueue has changed and p
1357 * is actually now running somewhere else!
1358 */
1359 while (task_running(rq, p)) {
1360 if (match_state && unlikely(p->state != match_state))
1361 return 0;
1362 cpu_relax();
1363 }
1364
1365 /*
1366 * Ok, time to look more closely! We need the rq
1367 * lock now, to be *sure*. If we're wrong, we'll
1368 * just go back and repeat.
1369 */
1370 rq = task_rq_lock(p, &rf);
1371 trace_sched_wait_task(p);
1372 running = task_running(rq, p);
1373 queued = task_on_rq_queued(p);
1374 ncsw = 0;
1375 if (!match_state || p->state == match_state)
1376 ncsw = p->nvcsw | LONG_MIN; /* sets MSB */
1377 task_rq_unlock(rq, p, &rf);
1378
1379 /*
1380 * If it changed from the expected state, bail out now.
1381 */
1382 if (unlikely(!ncsw))
1383 break;
1384
1385 /*
1386 * Was it really running after all now that we
1387 * checked with the proper locks actually held?
1388 *
1389 * Oops. Go back and try again..
1390 */
1391 if (unlikely(running)) {
1392 cpu_relax();
1393 continue;
1394 }
1395
1396 /*
1397 * It's not enough that it's not actively running,
1398 * it must be off the runqueue _entirely_, and not
1399 * preempted!
1400 *
1401 * So if it was still runnable (but just not actively
1402 * running right now), it's preempted, and we should
1403 * yield - it could be a while.
1404 */
1405 if (unlikely(queued)) {
1406 ktime_t to = NSEC_PER_SEC / HZ;
1407
1408 set_current_state(TASK_UNINTERRUPTIBLE);
1409 schedule_hrtimeout(&to, HRTIMER_MODE_REL);
1410 continue;
1411 }
1412
1413 /*
1414 * Ahh, all good. It wasn't running, and it wasn't
1415 * runnable, which means that it will never become
1416 * running in the future either. We're all done!
1417 */
1418 break;
1419 }
1420
1421 return ncsw;
1422}
1423
1424/***
1425 * kick_process - kick a running thread to enter/exit the kernel
1426 * @p: the to-be-kicked thread
1427 *
1428 * Cause a process which is running on another CPU to enter
1429 * kernel-mode, without any delay. (to get signals handled.)
1430 *
1431 * NOTE: this function doesn't have to take the runqueue lock,
1432 * because all it wants to ensure is that the remote task enters
1433 * the kernel. If the IPI races and the task has been migrated
1434 * to another CPU then no harm is done and the purpose has been
1435 * achieved as well.
1436 */
1437void kick_process(struct task_struct *p)
1438{
1439 int cpu;
1440
1441 preempt_disable();
1442 cpu = task_cpu(p);
1443 if ((cpu != smp_processor_id()) && task_curr(p))
1444 smp_send_reschedule(cpu);
1445 preempt_enable();
1446}
1447EXPORT_SYMBOL_GPL(kick_process);
1448
1449/*
1450 * ->cpus_allowed is protected by both rq->lock and p->pi_lock
1451 *
1452 * A few notes on cpu_active vs cpu_online:
1453 *
1454 * - cpu_active must be a subset of cpu_online
1455 *
1456 * - on CPU-up we allow per-CPU kthreads on the online && !active CPU,
1457 * see __set_cpus_allowed_ptr(). At this point the newly online
1458 * CPU isn't yet part of the sched domains, and balancing will not
1459 * see it.
1460 *
1461 * - on CPU-down we clear cpu_active() to mask the sched domains and
1462 * avoid the load balancer to place new tasks on the to be removed
1463 * CPU. Existing tasks will remain running there and will be taken
1464 * off.
1465 *
1466 * This means that fallback selection must not select !active CPUs.
1467 * And can assume that any active CPU must be online. Conversely
1468 * select_task_rq() below may allow selection of !active CPUs in order
1469 * to satisfy the above rules.
1470 */
1471static int select_fallback_rq(int cpu, struct task_struct *p)
1472{
1473 int nid = cpu_to_node(cpu);
1474 const struct cpumask *nodemask = NULL;
1475 enum { cpuset, possible, fail } state = cpuset;
1476 int dest_cpu;
1477
1478 /*
1479 * If the node that the CPU is on has been offlined, cpu_to_node()
1480 * will return -1. There is no CPU on the node, and we should
1481 * select the CPU on the other node.
1482 */
1483 if (nid != -1) {
1484 nodemask = cpumask_of_node(nid);
1485
1486 /* Look for allowed, online CPU in same node. */
1487 for_each_cpu(dest_cpu, nodemask) {
1488 if (!cpu_active(dest_cpu))
1489 continue;
1490 if (cpumask_test_cpu(dest_cpu, &p->cpus_allowed))
1491 return dest_cpu;
1492 }
1493 }
1494
1495 for (;;) {
1496 /* Any allowed, online CPU? */
1497 for_each_cpu(dest_cpu, &p->cpus_allowed) {
1498 if (!is_cpu_allowed(p, dest_cpu))
1499 continue;
1500
1501 goto out;
1502 }
1503
1504 /* No more Mr. Nice Guy. */
1505 switch (state) {
1506 case cpuset:
1507 if (IS_ENABLED(CONFIG_CPUSETS)) {
1508 cpuset_cpus_allowed_fallback(p);
1509 state = possible;
1510 break;
1511 }
1512 /* Fall-through */
1513 case possible:
1514 do_set_cpus_allowed(p, cpu_possible_mask);
1515 state = fail;
1516 break;
1517
1518 case fail:
1519 BUG();
1520 break;
1521 }
1522 }
1523
1524out:
1525 if (state != cpuset) {
1526 /*
1527 * Don't tell them about moving exiting tasks or
1528 * kernel threads (both mm NULL), since they never
1529 * leave kernel.
1530 */
1531 if (p->mm && printk_ratelimit()) {
1532 printk_deferred("process %d (%s) no longer affine to cpu%d\n",
1533 task_pid_nr(p), p->comm, cpu);
1534 }
1535 }
1536
1537 return dest_cpu;
1538}
1539
1540/*
1541 * The caller (fork, wakeup) owns p->pi_lock, ->cpus_allowed is stable.
1542 */
1543static inline
1544int select_task_rq(struct task_struct *p, int cpu, int sd_flags, int wake_flags)
1545{
1546 lockdep_assert_held(&p->pi_lock);
1547
1548 if (p->nr_cpus_allowed > 1)
1549 cpu = p->sched_class->select_task_rq(p, cpu, sd_flags, wake_flags);
1550 else
1551 cpu = cpumask_any(&p->cpus_allowed);
1552
1553 /*
1554 * In order not to call set_task_cpu() on a blocking task we need
1555 * to rely on ttwu() to place the task on a valid ->cpus_allowed
1556 * CPU.
1557 *
1558 * Since this is common to all placement strategies, this lives here.
1559 *
1560 * [ this allows ->select_task() to simply return task_cpu(p) and
1561 * not worry about this generic constraint ]
1562 */
1563 if (unlikely(!is_cpu_allowed(p, cpu)))
1564 cpu = select_fallback_rq(task_cpu(p), p);
1565
1566 return cpu;
1567}
1568
1569static void update_avg(u64 *avg, u64 sample)
1570{
1571 s64 diff = sample - *avg;
1572 *avg += diff >> 3;
1573}
1574
1575void sched_set_stop_task(int cpu, struct task_struct *stop)
1576{
1577 struct sched_param param = { .sched_priority = MAX_RT_PRIO - 1 };
1578 struct task_struct *old_stop = cpu_rq(cpu)->stop;
1579
1580 if (stop) {
1581 /*
1582 * Make it appear like a SCHED_FIFO task, its something
1583 * userspace knows about and won't get confused about.
1584 *
1585 * Also, it will make PI more or less work without too
1586 * much confusion -- but then, stop work should not
1587 * rely on PI working anyway.
1588 */
1589 sched_setscheduler_nocheck(stop, SCHED_FIFO, ¶m);
1590
1591 stop->sched_class = &stop_sched_class;
1592 }
1593
1594 cpu_rq(cpu)->stop = stop;
1595
1596 if (old_stop) {
1597 /*
1598 * Reset it back to a normal scheduling class so that
1599 * it can die in pieces.
1600 */
1601 old_stop->sched_class = &rt_sched_class;
1602 }
1603}
1604
1605#else
1606
1607static inline int __set_cpus_allowed_ptr(struct task_struct *p,
1608 const struct cpumask *new_mask, bool check)
1609{
1610 return set_cpus_allowed_ptr(p, new_mask);
1611}
1612
1613#endif /* CONFIG_SMP */
1614
1615static void
1616ttwu_stat(struct task_struct *p, int cpu, int wake_flags)
1617{
1618 struct rq *rq;
1619
1620 if (!schedstat_enabled())
1621 return;
1622
1623 rq = this_rq();
1624
1625#ifdef CONFIG_SMP
1626 if (cpu == rq->cpu) {
1627 __schedstat_inc(rq->ttwu_local);
1628 __schedstat_inc(p->se.statistics.nr_wakeups_local);
1629 } else {
1630 struct sched_domain *sd;
1631
1632 __schedstat_inc(p->se.statistics.nr_wakeups_remote);
1633 rcu_read_lock();
1634 for_each_domain(rq->cpu, sd) {
1635 if (cpumask_test_cpu(cpu, sched_domain_span(sd))) {
1636 __schedstat_inc(sd->ttwu_wake_remote);
1637 break;
1638 }
1639 }
1640 rcu_read_unlock();
1641 }
1642
1643 if (wake_flags & WF_MIGRATED)
1644 __schedstat_inc(p->se.statistics.nr_wakeups_migrate);
1645#endif /* CONFIG_SMP */
1646
1647 __schedstat_inc(rq->ttwu_count);
1648 __schedstat_inc(p->se.statistics.nr_wakeups);
1649
1650 if (wake_flags & WF_SYNC)
1651 __schedstat_inc(p->se.statistics.nr_wakeups_sync);
1652}
1653
1654static inline void ttwu_activate(struct rq *rq, struct task_struct *p, int en_flags)
1655{
1656 activate_task(rq, p, en_flags);
1657 p->on_rq = TASK_ON_RQ_QUEUED;
1658
1659 /* If a worker is waking up, notify the workqueue: */
1660 if (p->flags & PF_WQ_WORKER)
1661 wq_worker_waking_up(p, cpu_of(rq));
1662}
1663
1664/*
1665 * Mark the task runnable and perform wakeup-preemption.
1666 */
1667static void ttwu_do_wakeup(struct rq *rq, struct task_struct *p, int wake_flags,
1668 struct rq_flags *rf)
1669{
1670 check_preempt_curr(rq, p, wake_flags);
1671 p->state = TASK_RUNNING;
1672 trace_sched_wakeup(p);
1673
1674#ifdef CONFIG_SMP
1675 if (p->sched_class->task_woken) {
1676 /*
1677 * Our task @p is fully woken up and running; so its safe to
1678 * drop the rq->lock, hereafter rq is only used for statistics.
1679 */
1680 rq_unpin_lock(rq, rf);
1681 p->sched_class->task_woken(rq, p);
1682 rq_repin_lock(rq, rf);
1683 }
1684
1685 if (rq->idle_stamp) {
1686 u64 delta = rq_clock(rq) - rq->idle_stamp;
1687 u64 max = 2*rq->max_idle_balance_cost;
1688
1689 update_avg(&rq->avg_idle, delta);
1690
1691 if (rq->avg_idle > max)
1692 rq->avg_idle = max;
1693
1694 rq->idle_stamp = 0;
1695 }
1696#endif
1697}
1698
1699static void
1700ttwu_do_activate(struct rq *rq, struct task_struct *p, int wake_flags,
1701 struct rq_flags *rf)
1702{
1703 int en_flags = ENQUEUE_WAKEUP | ENQUEUE_NOCLOCK;
1704
1705 lockdep_assert_held(&rq->lock);
1706
1707#ifdef CONFIG_SMP
1708 if (p->sched_contributes_to_load)
1709 rq->nr_uninterruptible--;
1710
1711 if (wake_flags & WF_MIGRATED)
1712 en_flags |= ENQUEUE_MIGRATED;
1713#endif
1714
1715 ttwu_activate(rq, p, en_flags);
1716 ttwu_do_wakeup(rq, p, wake_flags, rf);
1717}
1718
1719/*
1720 * Called in case the task @p isn't fully descheduled from its runqueue,
1721 * in this case we must do a remote wakeup. Its a 'light' wakeup though,
1722 * since all we need to do is flip p->state to TASK_RUNNING, since
1723 * the task is still ->on_rq.
1724 */
1725static int ttwu_remote(struct task_struct *p, int wake_flags)
1726{
1727 struct rq_flags rf;
1728 struct rq *rq;
1729 int ret = 0;
1730
1731 rq = __task_rq_lock(p, &rf);
1732 if (task_on_rq_queued(p)) {
1733 /* check_preempt_curr() may use rq clock */
1734 update_rq_clock(rq);
1735 ttwu_do_wakeup(rq, p, wake_flags, &rf);
1736 ret = 1;
1737 }
1738 __task_rq_unlock(rq, &rf);
1739
1740 return ret;
1741}
1742
1743#ifdef CONFIG_SMP
1744void sched_ttwu_pending(void)
1745{
1746 struct rq *rq = this_rq();
1747 struct llist_node *llist = llist_del_all(&rq->wake_list);
1748 struct task_struct *p, *t;
1749 struct rq_flags rf;
1750
1751 if (!llist)
1752 return;
1753
1754 rq_lock_irqsave(rq, &rf);
1755 update_rq_clock(rq);
1756
1757 llist_for_each_entry_safe(p, t, llist, wake_entry)
1758 ttwu_do_activate(rq, p, p->sched_remote_wakeup ? WF_MIGRATED : 0, &rf);
1759
1760 rq_unlock_irqrestore(rq, &rf);
1761}
1762
1763void scheduler_ipi(void)
1764{
1765 /*
1766 * Fold TIF_NEED_RESCHED into the preempt_count; anybody setting
1767 * TIF_NEED_RESCHED remotely (for the first time) will also send
1768 * this IPI.
1769 */
1770 preempt_fold_need_resched();
1771
1772 if (llist_empty(&this_rq()->wake_list) && !got_nohz_idle_kick())
1773 return;
1774
1775 /*
1776 * Not all reschedule IPI handlers call irq_enter/irq_exit, since
1777 * traditionally all their work was done from the interrupt return
1778 * path. Now that we actually do some work, we need to make sure
1779 * we do call them.
1780 *
1781 * Some archs already do call them, luckily irq_enter/exit nest
1782 * properly.
1783 *
1784 * Arguably we should visit all archs and update all handlers,
1785 * however a fair share of IPIs are still resched only so this would
1786 * somewhat pessimize the simple resched case.
1787 */
1788 irq_enter();
1789 sched_ttwu_pending();
1790
1791 /*
1792 * Check if someone kicked us for doing the nohz idle load balance.
1793 */
1794 if (unlikely(got_nohz_idle_kick())) {
1795 this_rq()->idle_balance = 1;
1796 raise_softirq_irqoff(SCHED_SOFTIRQ);
1797 }
1798 irq_exit();
1799}
1800
1801static void ttwu_queue_remote(struct task_struct *p, int cpu, int wake_flags)
1802{
1803 struct rq *rq = cpu_rq(cpu);
1804
1805 p->sched_remote_wakeup = !!(wake_flags & WF_MIGRATED);
1806
1807 if (llist_add(&p->wake_entry, &cpu_rq(cpu)->wake_list)) {
1808 if (!set_nr_if_polling(rq->idle))
1809 smp_send_reschedule(cpu);
1810 else
1811 trace_sched_wake_idle_without_ipi(cpu);
1812 }
1813}
1814
1815void wake_up_if_idle(int cpu)
1816{
1817 struct rq *rq = cpu_rq(cpu);
1818 struct rq_flags rf;
1819
1820 rcu_read_lock();
1821
1822 if (!is_idle_task(rcu_dereference(rq->curr)))
1823 goto out;
1824
1825 if (set_nr_if_polling(rq->idle)) {
1826 trace_sched_wake_idle_without_ipi(cpu);
1827 } else {
1828 rq_lock_irqsave(rq, &rf);
1829 if (is_idle_task(rq->curr))
1830 smp_send_reschedule(cpu);
1831 /* Else CPU is not idle, do nothing here: */
1832 rq_unlock_irqrestore(rq, &rf);
1833 }
1834
1835out:
1836 rcu_read_unlock();
1837}
1838
1839bool cpus_share_cache(int this_cpu, int that_cpu)
1840{
1841 return per_cpu(sd_llc_id, this_cpu) == per_cpu(sd_llc_id, that_cpu);
1842}
1843#endif /* CONFIG_SMP */
1844
1845static void ttwu_queue(struct task_struct *p, int cpu, int wake_flags)
1846{
1847 struct rq *rq = cpu_rq(cpu);
1848 struct rq_flags rf;
1849
1850#if defined(CONFIG_SMP)
1851 if (sched_feat(TTWU_QUEUE) && !cpus_share_cache(smp_processor_id(), cpu)) {
1852 sched_clock_cpu(cpu); /* Sync clocks across CPUs */
1853 ttwu_queue_remote(p, cpu, wake_flags);
1854 return;
1855 }
1856#endif
1857
1858 rq_lock(rq, &rf);
1859 update_rq_clock(rq);
1860 ttwu_do_activate(rq, p, wake_flags, &rf);
1861 rq_unlock(rq, &rf);
1862}
1863
1864/*
1865 * Notes on Program-Order guarantees on SMP systems.
1866 *
1867 * MIGRATION
1868 *
1869 * The basic program-order guarantee on SMP systems is that when a task [t]
1870 * migrates, all its activity on its old CPU [c0] happens-before any subsequent
1871 * execution on its new CPU [c1].
1872 *
1873 * For migration (of runnable tasks) this is provided by the following means:
1874 *
1875 * A) UNLOCK of the rq(c0)->lock scheduling out task t
1876 * B) migration for t is required to synchronize *both* rq(c0)->lock and
1877 * rq(c1)->lock (if not at the same time, then in that order).
1878 * C) LOCK of the rq(c1)->lock scheduling in task
1879 *
1880 * Transitivity guarantees that B happens after A and C after B.
1881 * Note: we only require RCpc transitivity.
1882 * Note: the CPU doing B need not be c0 or c1
1883 *
1884 * Example:
1885 *
1886 * CPU0 CPU1 CPU2
1887 *
1888 * LOCK rq(0)->lock
1889 * sched-out X
1890 * sched-in Y
1891 * UNLOCK rq(0)->lock
1892 *
1893 * LOCK rq(0)->lock // orders against CPU0
1894 * dequeue X
1895 * UNLOCK rq(0)->lock
1896 *
1897 * LOCK rq(1)->lock
1898 * enqueue X
1899 * UNLOCK rq(1)->lock
1900 *
1901 * LOCK rq(1)->lock // orders against CPU2
1902 * sched-out Z
1903 * sched-in X
1904 * UNLOCK rq(1)->lock
1905 *
1906 *
1907 * BLOCKING -- aka. SLEEP + WAKEUP
1908 *
1909 * For blocking we (obviously) need to provide the same guarantee as for
1910 * migration. However the means are completely different as there is no lock
1911 * chain to provide order. Instead we do:
1912 *
1913 * 1) smp_store_release(X->on_cpu, 0)
1914 * 2) smp_cond_load_acquire(!X->on_cpu)
1915 *
1916 * Example:
1917 *
1918 * CPU0 (schedule) CPU1 (try_to_wake_up) CPU2 (schedule)
1919 *
1920 * LOCK rq(0)->lock LOCK X->pi_lock
1921 * dequeue X
1922 * sched-out X
1923 * smp_store_release(X->on_cpu, 0);
1924 *
1925 * smp_cond_load_acquire(&X->on_cpu, !VAL);
1926 * X->state = WAKING
1927 * set_task_cpu(X,2)
1928 *
1929 * LOCK rq(2)->lock
1930 * enqueue X
1931 * X->state = RUNNING
1932 * UNLOCK rq(2)->lock
1933 *
1934 * LOCK rq(2)->lock // orders against CPU1
1935 * sched-out Z
1936 * sched-in X
1937 * UNLOCK rq(2)->lock
1938 *
1939 * UNLOCK X->pi_lock
1940 * UNLOCK rq(0)->lock
1941 *
1942 *
1943 * However; for wakeups there is a second guarantee we must provide, namely we
1944 * must observe the state that lead to our wakeup. That is, not only must our
1945 * task observe its own prior state, it must also observe the stores prior to
1946 * its wakeup.
1947 *
1948 * This means that any means of doing remote wakeups must order the CPU doing
1949 * the wakeup against the CPU the task is going to end up running on. This,
1950 * however, is already required for the regular Program-Order guarantee above,
1951 * since the waking CPU is the one issueing the ACQUIRE (smp_cond_load_acquire).
1952 *
1953 */
1954
1955/**
1956 * try_to_wake_up - wake up a thread
1957 * @p: the thread to be awakened
1958 * @state: the mask of task states that can be woken
1959 * @wake_flags: wake modifier flags (WF_*)
1960 *
1961 * If (@state & @p->state) @p->state = TASK_RUNNING.
1962 *
1963 * If the task was not queued/runnable, also place it back on a runqueue.
1964 *
1965 * Atomic against schedule() which would dequeue a task, also see
1966 * set_current_state().
1967 *
1968 * Return: %true if @p->state changes (an actual wakeup was done),
1969 * %false otherwise.
1970 */
1971static int
1972try_to_wake_up(struct task_struct *p, unsigned int state, int wake_flags)
1973{
1974 unsigned long flags;
1975 int cpu, success = 0;
1976
1977 /*
1978 * If we are going to wake up a thread waiting for CONDITION we
1979 * need to ensure that CONDITION=1 done by the caller can not be
1980 * reordered with p->state check below. This pairs with mb() in
1981 * set_current_state() the waiting thread does.
1982 */
1983 raw_spin_lock_irqsave(&p->pi_lock, flags);
1984 smp_mb__after_spinlock();
1985 if (!(p->state & state))
1986 goto out;
1987
1988 trace_sched_waking(p);
1989
1990 /* We're going to change ->state: */
1991 success = 1;
1992 cpu = task_cpu(p);
1993
1994 /*
1995 * Ensure we load p->on_rq _after_ p->state, otherwise it would
1996 * be possible to, falsely, observe p->on_rq == 0 and get stuck
1997 * in smp_cond_load_acquire() below.
1998 *
1999 * sched_ttwu_pending() try_to_wake_up()
2000 * [S] p->on_rq = 1; [L] P->state
2001 * UNLOCK rq->lock -----.
2002 * \
2003 * +--- RMB
2004 * schedule() /
2005 * LOCK rq->lock -----'
2006 * UNLOCK rq->lock
2007 *
2008 * [task p]
2009 * [S] p->state = UNINTERRUPTIBLE [L] p->on_rq
2010 *
2011 * Pairs with the UNLOCK+LOCK on rq->lock from the
2012 * last wakeup of our task and the schedule that got our task
2013 * current.
2014 */
2015 smp_rmb();
2016 if (p->on_rq && ttwu_remote(p, wake_flags))
2017 goto stat;
2018
2019#ifdef CONFIG_SMP
2020 /*
2021 * Ensure we load p->on_cpu _after_ p->on_rq, otherwise it would be
2022 * possible to, falsely, observe p->on_cpu == 0.
2023 *
2024 * One must be running (->on_cpu == 1) in order to remove oneself
2025 * from the runqueue.
2026 *
2027 * [S] ->on_cpu = 1; [L] ->on_rq
2028 * UNLOCK rq->lock
2029 * RMB
2030 * LOCK rq->lock
2031 * [S] ->on_rq = 0; [L] ->on_cpu
2032 *
2033 * Pairs with the full barrier implied in the UNLOCK+LOCK on rq->lock
2034 * from the consecutive calls to schedule(); the first switching to our
2035 * task, the second putting it to sleep.
2036 */
2037 smp_rmb();
2038
2039 /*
2040 * If the owning (remote) CPU is still in the middle of schedule() with
2041 * this task as prev, wait until its done referencing the task.
2042 *
2043 * Pairs with the smp_store_release() in finish_task().
2044 *
2045 * This ensures that tasks getting woken will be fully ordered against
2046 * their previous state and preserve Program Order.
2047 */
2048 smp_cond_load_acquire(&p->on_cpu, !VAL);
2049
2050 p->sched_contributes_to_load = !!task_contributes_to_load(p);
2051 p->state = TASK_WAKING;
2052
2053 if (p->in_iowait) {
2054 delayacct_blkio_end(p);
2055 atomic_dec(&task_rq(p)->nr_iowait);
2056 }
2057
2058 cpu = select_task_rq(p, p->wake_cpu, SD_BALANCE_WAKE, wake_flags);
2059 if (task_cpu(p) != cpu) {
2060 wake_flags |= WF_MIGRATED;
2061 set_task_cpu(p, cpu);
2062 }
2063
2064#else /* CONFIG_SMP */
2065
2066 if (p->in_iowait) {
2067 delayacct_blkio_end(p);
2068 atomic_dec(&task_rq(p)->nr_iowait);
2069 }
2070
2071#endif /* CONFIG_SMP */
2072
2073 ttwu_queue(p, cpu, wake_flags);
2074stat:
2075 ttwu_stat(p, cpu, wake_flags);
2076out:
2077 raw_spin_unlock_irqrestore(&p->pi_lock, flags);
2078
2079 return success;
2080}
2081
2082/**
2083 * try_to_wake_up_local - try to wake up a local task with rq lock held
2084 * @p: the thread to be awakened
2085 * @rf: request-queue flags for pinning
2086 *
2087 * Put @p on the run-queue if it's not already there. The caller must
2088 * ensure that this_rq() is locked, @p is bound to this_rq() and not
2089 * the current task.
2090 */
2091static void try_to_wake_up_local(struct task_struct *p, struct rq_flags *rf)
2092{
2093 struct rq *rq = task_rq(p);
2094
2095 if (WARN_ON_ONCE(rq != this_rq()) ||
2096 WARN_ON_ONCE(p == current))
2097 return;
2098
2099 lockdep_assert_held(&rq->lock);
2100
2101 if (!raw_spin_trylock(&p->pi_lock)) {
2102 /*
2103 * This is OK, because current is on_cpu, which avoids it being
2104 * picked for load-balance and preemption/IRQs are still
2105 * disabled avoiding further scheduler activity on it and we've
2106 * not yet picked a replacement task.
2107 */
2108 rq_unlock(rq, rf);
2109 raw_spin_lock(&p->pi_lock);
2110 rq_relock(rq, rf);
2111 }
2112
2113 if (!(p->state & TASK_NORMAL))
2114 goto out;
2115
2116 trace_sched_waking(p);
2117
2118 if (!task_on_rq_queued(p)) {
2119 if (p->in_iowait) {
2120 delayacct_blkio_end(p);
2121 atomic_dec(&rq->nr_iowait);
2122 }
2123 ttwu_activate(rq, p, ENQUEUE_WAKEUP | ENQUEUE_NOCLOCK);
2124 }
2125
2126 ttwu_do_wakeup(rq, p, 0, rf);
2127 ttwu_stat(p, smp_processor_id(), 0);
2128out:
2129 raw_spin_unlock(&p->pi_lock);
2130}
2131
2132/**
2133 * wake_up_process - Wake up a specific process
2134 * @p: The process to be woken up.
2135 *
2136 * Attempt to wake up the nominated process and move it to the set of runnable
2137 * processes.
2138 *
2139 * Return: 1 if the process was woken up, 0 if it was already running.
2140 *
2141 * It may be assumed that this function implies a write memory barrier before
2142 * changing the task state if and only if any tasks are woken up.
2143 */
2144int wake_up_process(struct task_struct *p)
2145{
2146 return try_to_wake_up(p, TASK_NORMAL, 0);
2147}
2148EXPORT_SYMBOL(wake_up_process);
2149
2150int wake_up_state(struct task_struct *p, unsigned int state)
2151{
2152 return try_to_wake_up(p, state, 0);
2153}
2154
2155/*
2156 * Perform scheduler related setup for a newly forked process p.
2157 * p is forked by current.
2158 *
2159 * __sched_fork() is basic setup used by init_idle() too:
2160 */
2161static void __sched_fork(unsigned long clone_flags, struct task_struct *p)
2162{
2163 p->on_rq = 0;
2164
2165 p->se.on_rq = 0;
2166 p->se.exec_start = 0;
2167 p->se.sum_exec_runtime = 0;
2168 p->se.prev_sum_exec_runtime = 0;
2169 p->se.nr_migrations = 0;
2170 p->se.vruntime = 0;
2171 INIT_LIST_HEAD(&p->se.group_node);
2172
2173#ifdef CONFIG_FAIR_GROUP_SCHED
2174 p->se.cfs_rq = NULL;
2175#endif
2176
2177#ifdef CONFIG_SCHEDSTATS
2178 /* Even if schedstat is disabled, there should not be garbage */
2179 memset(&p->se.statistics, 0, sizeof(p->se.statistics));
2180#endif
2181
2182 RB_CLEAR_NODE(&p->dl.rb_node);
2183 init_dl_task_timer(&p->dl);
2184 init_dl_inactive_task_timer(&p->dl);
2185 __dl_clear_params(p);
2186
2187 INIT_LIST_HEAD(&p->rt.run_list);
2188 p->rt.timeout = 0;
2189 p->rt.time_slice = sched_rr_timeslice;
2190 p->rt.on_rq = 0;
2191 p->rt.on_list = 0;
2192
2193#ifdef CONFIG_PREEMPT_NOTIFIERS
2194 INIT_HLIST_HEAD(&p->preempt_notifiers);
2195#endif
2196
2197#ifdef CONFIG_NUMA_BALANCING
2198 if (p->mm && atomic_read(&p->mm->mm_users) == 1) {
2199 p->mm->numa_next_scan = jiffies + msecs_to_jiffies(sysctl_numa_balancing_scan_delay);
2200 p->mm->numa_scan_seq = 0;
2201 }
2202
2203 if (clone_flags & CLONE_VM)
2204 p->numa_preferred_nid = current->numa_preferred_nid;
2205 else
2206 p->numa_preferred_nid = -1;
2207
2208 p->node_stamp = 0ULL;
2209 p->numa_scan_seq = p->mm ? p->mm->numa_scan_seq : 0;
2210 p->numa_scan_period = sysctl_numa_balancing_scan_delay;
2211 p->numa_work.next = &p->numa_work;
2212 p->numa_faults = NULL;
2213 p->last_task_numa_placement = 0;
2214 p->last_sum_exec_runtime = 0;
2215
2216 p->numa_group = NULL;
2217#endif /* CONFIG_NUMA_BALANCING */
2218}
2219
2220DEFINE_STATIC_KEY_FALSE(sched_numa_balancing);
2221
2222#ifdef CONFIG_NUMA_BALANCING
2223
2224void set_numabalancing_state(bool enabled)
2225{
2226 if (enabled)
2227 static_branch_enable(&sched_numa_balancing);
2228 else
2229 static_branch_disable(&sched_numa_balancing);
2230}
2231
2232#ifdef CONFIG_PROC_SYSCTL
2233int sysctl_numa_balancing(struct ctl_table *table, int write,
2234 void __user *buffer, size_t *lenp, loff_t *ppos)
2235{
2236 struct ctl_table t;
2237 int err;
2238 int state = static_branch_likely(&sched_numa_balancing);
2239
2240 if (write && !capable(CAP_SYS_ADMIN))
2241 return -EPERM;
2242
2243 t = *table;
2244 t.data = &state;
2245 err = proc_dointvec_minmax(&t, write, buffer, lenp, ppos);
2246 if (err < 0)
2247 return err;
2248 if (write)
2249 set_numabalancing_state(state);
2250 return err;
2251}
2252#endif
2253#endif
2254
2255#ifdef CONFIG_SCHEDSTATS
2256
2257DEFINE_STATIC_KEY_FALSE(sched_schedstats);
2258static bool __initdata __sched_schedstats = false;
2259
2260static void set_schedstats(bool enabled)
2261{
2262 if (enabled)
2263 static_branch_enable(&sched_schedstats);
2264 else
2265 static_branch_disable(&sched_schedstats);
2266}
2267
2268void force_schedstat_enabled(void)
2269{
2270 if (!schedstat_enabled()) {
2271 pr_info("kernel profiling enabled schedstats, disable via kernel.sched_schedstats.\n");
2272 static_branch_enable(&sched_schedstats);
2273 }
2274}
2275
2276static int __init setup_schedstats(char *str)
2277{
2278 int ret = 0;
2279 if (!str)
2280 goto out;
2281
2282 /*
2283 * This code is called before jump labels have been set up, so we can't
2284 * change the static branch directly just yet. Instead set a temporary
2285 * variable so init_schedstats() can do it later.
2286 */
2287 if (!strcmp(str, "enable")) {
2288 __sched_schedstats = true;
2289 ret = 1;
2290 } else if (!strcmp(str, "disable")) {
2291 __sched_schedstats = false;
2292 ret = 1;
2293 }
2294out:
2295 if (!ret)
2296 pr_warn("Unable to parse schedstats=\n");
2297
2298 return ret;
2299}
2300__setup("schedstats=", setup_schedstats);
2301
2302static void __init init_schedstats(void)
2303{
2304 set_schedstats(__sched_schedstats);
2305}
2306
2307#ifdef CONFIG_PROC_SYSCTL
2308int sysctl_schedstats(struct ctl_table *table, int write,
2309 void __user *buffer, size_t *lenp, loff_t *ppos)
2310{
2311 struct ctl_table t;
2312 int err;
2313 int state = static_branch_likely(&sched_schedstats);
2314
2315 if (write && !capable(CAP_SYS_ADMIN))
2316 return -EPERM;
2317
2318 t = *table;
2319 t.data = &state;
2320 err = proc_dointvec_minmax(&t, write, buffer, lenp, ppos);
2321 if (err < 0)
2322 return err;
2323 if (write)
2324 set_schedstats(state);
2325 return err;
2326}
2327#endif /* CONFIG_PROC_SYSCTL */
2328#else /* !CONFIG_SCHEDSTATS */
2329static inline void init_schedstats(void) {}
2330#endif /* CONFIG_SCHEDSTATS */
2331
2332/*
2333 * fork()/clone()-time setup:
2334 */
2335int sched_fork(unsigned long clone_flags, struct task_struct *p)
2336{
2337 unsigned long flags;
2338 int cpu = get_cpu();
2339
2340 __sched_fork(clone_flags, p);
2341 /*
2342 * We mark the process as NEW here. This guarantees that
2343 * nobody will actually run it, and a signal or other external
2344 * event cannot wake it up and insert it on the runqueue either.
2345 */
2346 p->state = TASK_NEW;
2347
2348 /*
2349 * Make sure we do not leak PI boosting priority to the child.
2350 */
2351 p->prio = current->normal_prio;
2352
2353 /*
2354 * Revert to default priority/policy on fork if requested.
2355 */
2356 if (unlikely(p->sched_reset_on_fork)) {
2357 if (task_has_dl_policy(p) || task_has_rt_policy(p)) {
2358 p->policy = SCHED_NORMAL;
2359 p->static_prio = NICE_TO_PRIO(0);
2360 p->rt_priority = 0;
2361 } else if (PRIO_TO_NICE(p->static_prio) < 0)
2362 p->static_prio = NICE_TO_PRIO(0);
2363
2364 p->prio = p->normal_prio = __normal_prio(p);
2365 set_load_weight(p, false);
2366
2367 /*
2368 * We don't need the reset flag anymore after the fork. It has
2369 * fulfilled its duty:
2370 */
2371 p->sched_reset_on_fork = 0;
2372 }
2373
2374 if (dl_prio(p->prio)) {
2375 put_cpu();
2376 return -EAGAIN;
2377 } else if (rt_prio(p->prio)) {
2378 p->sched_class = &rt_sched_class;
2379 } else {
2380 p->sched_class = &fair_sched_class;
2381 }
2382
2383 init_entity_runnable_average(&p->se);
2384
2385 /*
2386 * The child is not yet in the pid-hash so no cgroup attach races,
2387 * and the cgroup is pinned to this child due to cgroup_fork()
2388 * is ran before sched_fork().
2389 *
2390 * Silence PROVE_RCU.
2391 */
2392 raw_spin_lock_irqsave(&p->pi_lock, flags);
2393 /*
2394 * We're setting the CPU for the first time, we don't migrate,
2395 * so use __set_task_cpu().
2396 */
2397 __set_task_cpu(p, cpu);
2398 if (p->sched_class->task_fork)
2399 p->sched_class->task_fork(p);
2400 raw_spin_unlock_irqrestore(&p->pi_lock, flags);
2401
2402#ifdef CONFIG_SCHED_INFO
2403 if (likely(sched_info_on()))
2404 memset(&p->sched_info, 0, sizeof(p->sched_info));
2405#endif
2406#if defined(CONFIG_SMP)
2407 p->on_cpu = 0;
2408#endif
2409 init_task_preempt_count(p);
2410#ifdef CONFIG_SMP
2411 plist_node_init(&p->pushable_tasks, MAX_PRIO);
2412 RB_CLEAR_NODE(&p->pushable_dl_tasks);
2413#endif
2414
2415 put_cpu();
2416 return 0;
2417}
2418
2419unsigned long to_ratio(u64 period, u64 runtime)
2420{
2421 if (runtime == RUNTIME_INF)
2422 return BW_UNIT;
2423
2424 /*
2425 * Doing this here saves a lot of checks in all
2426 * the calling paths, and returning zero seems
2427 * safe for them anyway.
2428 */
2429 if (period == 0)
2430 return 0;
2431
2432 return div64_u64(runtime << BW_SHIFT, period);
2433}
2434
2435/*
2436 * wake_up_new_task - wake up a newly created task for the first time.
2437 *
2438 * This function will do some initial scheduler statistics housekeeping
2439 * that must be done for every newly created context, then puts the task
2440 * on the runqueue and wakes it.
2441 */
2442void wake_up_new_task(struct task_struct *p)
2443{
2444 struct rq_flags rf;
2445 struct rq *rq;
2446
2447 raw_spin_lock_irqsave(&p->pi_lock, rf.flags);
2448 p->state = TASK_RUNNING;
2449#ifdef CONFIG_SMP
2450 /*
2451 * Fork balancing, do it here and not earlier because:
2452 * - cpus_allowed can change in the fork path
2453 * - any previously selected CPU might disappear through hotplug
2454 *
2455 * Use __set_task_cpu() to avoid calling sched_class::migrate_task_rq,
2456 * as we're not fully set-up yet.
2457 */
2458 p->recent_used_cpu = task_cpu(p);
2459 __set_task_cpu(p, select_task_rq(p, task_cpu(p), SD_BALANCE_FORK, 0));
2460#endif
2461 rq = __task_rq_lock(p, &rf);
2462 update_rq_clock(rq);
2463 post_init_entity_util_avg(&p->se);
2464
2465 activate_task(rq, p, ENQUEUE_NOCLOCK);
2466 p->on_rq = TASK_ON_RQ_QUEUED;
2467 trace_sched_wakeup_new(p);
2468 check_preempt_curr(rq, p, WF_FORK);
2469#ifdef CONFIG_SMP
2470 if (p->sched_class->task_woken) {
2471 /*
2472 * Nothing relies on rq->lock after this, so its fine to
2473 * drop it.
2474 */
2475 rq_unpin_lock(rq, &rf);
2476 p->sched_class->task_woken(rq, p);
2477 rq_repin_lock(rq, &rf);
2478 }
2479#endif
2480 task_rq_unlock(rq, p, &rf);
2481}
2482
2483#ifdef CONFIG_PREEMPT_NOTIFIERS
2484
2485static DEFINE_STATIC_KEY_FALSE(preempt_notifier_key);
2486
2487void preempt_notifier_inc(void)
2488{
2489 static_branch_inc(&preempt_notifier_key);
2490}
2491EXPORT_SYMBOL_GPL(preempt_notifier_inc);
2492
2493void preempt_notifier_dec(void)
2494{
2495 static_branch_dec(&preempt_notifier_key);
2496}
2497EXPORT_SYMBOL_GPL(preempt_notifier_dec);
2498
2499/**
2500 * preempt_notifier_register - tell me when current is being preempted & rescheduled
2501 * @notifier: notifier struct to register
2502 */
2503void preempt_notifier_register(struct preempt_notifier *notifier)
2504{
2505 if (!static_branch_unlikely(&preempt_notifier_key))
2506 WARN(1, "registering preempt_notifier while notifiers disabled\n");
2507
2508 hlist_add_head(¬ifier->link, ¤t->preempt_notifiers);
2509}
2510EXPORT_SYMBOL_GPL(preempt_notifier_register);
2511
2512/**
2513 * preempt_notifier_unregister - no longer interested in preemption notifications
2514 * @notifier: notifier struct to unregister
2515 *
2516 * This is *not* safe to call from within a preemption notifier.
2517 */
2518void preempt_notifier_unregister(struct preempt_notifier *notifier)
2519{
2520 hlist_del(¬ifier->link);
2521}
2522EXPORT_SYMBOL_GPL(preempt_notifier_unregister);
2523
2524static void __fire_sched_in_preempt_notifiers(struct task_struct *curr)
2525{
2526 struct preempt_notifier *notifier;
2527
2528 hlist_for_each_entry(notifier, &curr->preempt_notifiers, link)
2529 notifier->ops->sched_in(notifier, raw_smp_processor_id());
2530}
2531
2532static __always_inline void fire_sched_in_preempt_notifiers(struct task_struct *curr)
2533{
2534 if (static_branch_unlikely(&preempt_notifier_key))
2535 __fire_sched_in_preempt_notifiers(curr);
2536}
2537
2538static void
2539__fire_sched_out_preempt_notifiers(struct task_struct *curr,
2540 struct task_struct *next)
2541{
2542 struct preempt_notifier *notifier;
2543
2544 hlist_for_each_entry(notifier, &curr->preempt_notifiers, link)
2545 notifier->ops->sched_out(notifier, next);
2546}
2547
2548static __always_inline void
2549fire_sched_out_preempt_notifiers(struct task_struct *curr,
2550 struct task_struct *next)
2551{
2552 if (static_branch_unlikely(&preempt_notifier_key))
2553 __fire_sched_out_preempt_notifiers(curr, next);
2554}
2555
2556#else /* !CONFIG_PREEMPT_NOTIFIERS */
2557
2558static inline void fire_sched_in_preempt_notifiers(struct task_struct *curr)
2559{
2560}
2561
2562static inline void
2563fire_sched_out_preempt_notifiers(struct task_struct *curr,
2564 struct task_struct *next)
2565{
2566}
2567
2568#endif /* CONFIG_PREEMPT_NOTIFIERS */
2569
2570static inline void prepare_task(struct task_struct *next)
2571{
2572#ifdef CONFIG_SMP
2573 /*
2574 * Claim the task as running, we do this before switching to it
2575 * such that any running task will have this set.
2576 */
2577 next->on_cpu = 1;
2578#endif
2579}
2580
2581static inline void finish_task(struct task_struct *prev)
2582{
2583#ifdef CONFIG_SMP
2584 /*
2585 * After ->on_cpu is cleared, the task can be moved to a different CPU.
2586 * We must ensure this doesn't happen until the switch is completely
2587 * finished.
2588 *
2589 * In particular, the load of prev->state in finish_task_switch() must
2590 * happen before this.
2591 *
2592 * Pairs with the smp_cond_load_acquire() in try_to_wake_up().
2593 */
2594 smp_store_release(&prev->on_cpu, 0);
2595#endif
2596}
2597
2598static inline void
2599prepare_lock_switch(struct rq *rq, struct task_struct *next, struct rq_flags *rf)
2600{
2601 /*
2602 * Since the runqueue lock will be released by the next
2603 * task (which is an invalid locking op but in the case
2604 * of the scheduler it's an obvious special-case), so we
2605 * do an early lockdep release here:
2606 */
2607 rq_unpin_lock(rq, rf);
2608 spin_release(&rq->lock.dep_map, 1, _THIS_IP_);
2609#ifdef CONFIG_DEBUG_SPINLOCK
2610 /* this is a valid case when another task releases the spinlock */
2611 rq->lock.owner = next;
2612#endif
2613}
2614
2615static inline void finish_lock_switch(struct rq *rq)
2616{
2617 /*
2618 * If we are tracking spinlock dependencies then we have to
2619 * fix up the runqueue lock - which gets 'carried over' from
2620 * prev into current:
2621 */
2622 spin_acquire(&rq->lock.dep_map, 0, 0, _THIS_IP_);
2623 raw_spin_unlock_irq(&rq->lock);
2624}
2625
2626/*
2627 * NOP if the arch has not defined these:
2628 */
2629
2630#ifndef prepare_arch_switch
2631# define prepare_arch_switch(next) do { } while (0)
2632#endif
2633
2634#ifndef finish_arch_post_lock_switch
2635# define finish_arch_post_lock_switch() do { } while (0)
2636#endif
2637
2638/**
2639 * prepare_task_switch - prepare to switch tasks
2640 * @rq: the runqueue preparing to switch
2641 * @prev: the current task that is being switched out
2642 * @next: the task we are going to switch to.
2643 *
2644 * This is called with the rq lock held and interrupts off. It must
2645 * be paired with a subsequent finish_task_switch after the context
2646 * switch.
2647 *
2648 * prepare_task_switch sets up locking and calls architecture specific
2649 * hooks.
2650 */
2651static inline void
2652prepare_task_switch(struct rq *rq, struct task_struct *prev,
2653 struct task_struct *next)
2654{
2655 sched_info_switch(rq, prev, next);
2656 perf_event_task_sched_out(prev, next);
2657 fire_sched_out_preempt_notifiers(prev, next);
2658 prepare_task(next);
2659 prepare_arch_switch(next);
2660}
2661
2662/**
2663 * finish_task_switch - clean up after a task-switch
2664 * @prev: the thread we just switched away from.
2665 *
2666 * finish_task_switch must be called after the context switch, paired
2667 * with a prepare_task_switch call before the context switch.
2668 * finish_task_switch will reconcile locking set up by prepare_task_switch,
2669 * and do any other architecture-specific cleanup actions.
2670 *
2671 * Note that we may have delayed dropping an mm in context_switch(). If
2672 * so, we finish that here outside of the runqueue lock. (Doing it
2673 * with the lock held can cause deadlocks; see schedule() for
2674 * details.)
2675 *
2676 * The context switch have flipped the stack from under us and restored the
2677 * local variables which were saved when this task called schedule() in the
2678 * past. prev == current is still correct but we need to recalculate this_rq
2679 * because prev may have moved to another CPU.
2680 */
2681static struct rq *finish_task_switch(struct task_struct *prev)
2682 __releases(rq->lock)
2683{
2684 struct rq *rq = this_rq();
2685 struct mm_struct *mm = rq->prev_mm;
2686 long prev_state;
2687
2688 /*
2689 * The previous task will have left us with a preempt_count of 2
2690 * because it left us after:
2691 *
2692 * schedule()
2693 * preempt_disable(); // 1
2694 * __schedule()
2695 * raw_spin_lock_irq(&rq->lock) // 2
2696 *
2697 * Also, see FORK_PREEMPT_COUNT.
2698 */
2699 if (WARN_ONCE(preempt_count() != 2*PREEMPT_DISABLE_OFFSET,
2700 "corrupted preempt_count: %s/%d/0x%x\n",
2701 current->comm, current->pid, preempt_count()))
2702 preempt_count_set(FORK_PREEMPT_COUNT);
2703
2704 rq->prev_mm = NULL;
2705
2706 /*
2707 * A task struct has one reference for the use as "current".
2708 * If a task dies, then it sets TASK_DEAD in tsk->state and calls
2709 * schedule one last time. The schedule call will never return, and
2710 * the scheduled task must drop that reference.
2711 *
2712 * We must observe prev->state before clearing prev->on_cpu (in
2713 * finish_task), otherwise a concurrent wakeup can get prev
2714 * running on another CPU and we could rave with its RUNNING -> DEAD
2715 * transition, resulting in a double drop.
2716 */
2717 prev_state = prev->state;
2718 vtime_task_switch(prev);
2719 perf_event_task_sched_in(prev, current);
2720 finish_task(prev);
2721 finish_lock_switch(rq);
2722 finish_arch_post_lock_switch();
2723
2724 fire_sched_in_preempt_notifiers(current);
2725 /*
2726 * When switching through a kernel thread, the loop in
2727 * membarrier_{private,global}_expedited() may have observed that
2728 * kernel thread and not issued an IPI. It is therefore possible to
2729 * schedule between user->kernel->user threads without passing though
2730 * switch_mm(). Membarrier requires a barrier after storing to
2731 * rq->curr, before returning to userspace, so provide them here:
2732 *
2733 * - a full memory barrier for {PRIVATE,GLOBAL}_EXPEDITED, implicitly
2734 * provided by mmdrop(),
2735 * - a sync_core for SYNC_CORE.
2736 */
2737 if (mm) {
2738 membarrier_mm_sync_core_before_usermode(mm);
2739 mmdrop(mm);
2740 }
2741 if (unlikely(prev_state & (TASK_DEAD|TASK_PARKED))) {
2742 switch (prev_state) {
2743 case TASK_DEAD:
2744 if (prev->sched_class->task_dead)
2745 prev->sched_class->task_dead(prev);
2746
2747 /*
2748 * Remove function-return probe instances associated with this
2749 * task and put them back on the free list.
2750 */
2751 kprobe_flush_task(prev);
2752
2753 /* Task is done with its stack. */
2754 put_task_stack(prev);
2755
2756 put_task_struct(prev);
2757 break;
2758
2759 case TASK_PARKED:
2760 kthread_park_complete(prev);
2761 break;
2762 }
2763 }
2764
2765 tick_nohz_task_switch();
2766 return rq;
2767}
2768
2769#ifdef CONFIG_SMP
2770
2771/* rq->lock is NOT held, but preemption is disabled */
2772static void __balance_callback(struct rq *rq)
2773{
2774 struct callback_head *head, *next;
2775 void (*func)(struct rq *rq);
2776 unsigned long flags;
2777
2778 raw_spin_lock_irqsave(&rq->lock, flags);
2779 head = rq->balance_callback;
2780 rq->balance_callback = NULL;
2781 while (head) {
2782 func = (void (*)(struct rq *))head->func;
2783 next = head->next;
2784 head->next = NULL;
2785 head = next;
2786
2787 func(rq);
2788 }
2789 raw_spin_unlock_irqrestore(&rq->lock, flags);
2790}
2791
2792static inline void balance_callback(struct rq *rq)
2793{
2794 if (unlikely(rq->balance_callback))
2795 __balance_callback(rq);
2796}
2797
2798#else
2799
2800static inline void balance_callback(struct rq *rq)
2801{
2802}
2803
2804#endif
2805
2806/**
2807 * schedule_tail - first thing a freshly forked thread must call.
2808 * @prev: the thread we just switched away from.
2809 */
2810asmlinkage __visible void schedule_tail(struct task_struct *prev)
2811 __releases(rq->lock)
2812{
2813 struct rq *rq;
2814
2815 /*
2816 * New tasks start with FORK_PREEMPT_COUNT, see there and
2817 * finish_task_switch() for details.
2818 *
2819 * finish_task_switch() will drop rq->lock() and lower preempt_count
2820 * and the preempt_enable() will end up enabling preemption (on
2821 * PREEMPT_COUNT kernels).
2822 */
2823
2824 rq = finish_task_switch(prev);
2825 balance_callback(rq);
2826 preempt_enable();
2827
2828 if (current->set_child_tid)
2829 put_user(task_pid_vnr(current), current->set_child_tid);
2830}
2831
2832/*
2833 * context_switch - switch to the new MM and the new thread's register state.
2834 */
2835static __always_inline struct rq *
2836context_switch(struct rq *rq, struct task_struct *prev,
2837 struct task_struct *next, struct rq_flags *rf)
2838{
2839 struct mm_struct *mm, *oldmm;
2840
2841 prepare_task_switch(rq, prev, next);
2842
2843 mm = next->mm;
2844 oldmm = prev->active_mm;
2845 /*
2846 * For paravirt, this is coupled with an exit in switch_to to
2847 * combine the page table reload and the switch backend into
2848 * one hypercall.
2849 */
2850 arch_start_context_switch(prev);
2851
2852 /*
2853 * If mm is non-NULL, we pass through switch_mm(). If mm is
2854 * NULL, we will pass through mmdrop() in finish_task_switch().
2855 * Both of these contain the full memory barrier required by
2856 * membarrier after storing to rq->curr, before returning to
2857 * user-space.
2858 */
2859 if (!mm) {
2860 next->active_mm = oldmm;
2861 mmgrab(oldmm);
2862 enter_lazy_tlb(oldmm, next);
2863 } else
2864 switch_mm_irqs_off(oldmm, mm, next);
2865
2866 if (!prev->mm) {
2867 prev->active_mm = NULL;
2868 rq->prev_mm = oldmm;
2869 }
2870
2871 rq->clock_update_flags &= ~(RQCF_ACT_SKIP|RQCF_REQ_SKIP);
2872
2873 prepare_lock_switch(rq, next, rf);
2874
2875 /* Here we just switch the register state and the stack. */
2876 switch_to(prev, next, prev);
2877 barrier();
2878
2879 return finish_task_switch(prev);
2880}
2881
2882/*
2883 * nr_running and nr_context_switches:
2884 *
2885 * externally visible scheduler statistics: current number of runnable
2886 * threads, total number of context switches performed since bootup.
2887 */
2888unsigned long nr_running(void)
2889{
2890 unsigned long i, sum = 0;
2891
2892 for_each_online_cpu(i)
2893 sum += cpu_rq(i)->nr_running;
2894
2895 return sum;
2896}
2897
2898/*
2899 * Check if only the current task is running on the CPU.
2900 *
2901 * Caution: this function does not check that the caller has disabled
2902 * preemption, thus the result might have a time-of-check-to-time-of-use
2903 * race. The caller is responsible to use it correctly, for example:
2904 *
2905 * - from a non-preemptable section (of course)
2906 *
2907 * - from a thread that is bound to a single CPU
2908 *
2909 * - in a loop with very short iterations (e.g. a polling loop)
2910 */
2911bool single_task_running(void)
2912{
2913 return raw_rq()->nr_running == 1;
2914}
2915EXPORT_SYMBOL(single_task_running);
2916
2917unsigned long long nr_context_switches(void)
2918{
2919 int i;
2920 unsigned long long sum = 0;
2921
2922 for_each_possible_cpu(i)
2923 sum += cpu_rq(i)->nr_switches;
2924
2925 return sum;
2926}
2927
2928/*
2929 * IO-wait accounting, and how its mostly bollocks (on SMP).
2930 *
2931 * The idea behind IO-wait account is to account the idle time that we could
2932 * have spend running if it were not for IO. That is, if we were to improve the
2933 * storage performance, we'd have a proportional reduction in IO-wait time.
2934 *
2935 * This all works nicely on UP, where, when a task blocks on IO, we account
2936 * idle time as IO-wait, because if the storage were faster, it could've been
2937 * running and we'd not be idle.
2938 *
2939 * This has been extended to SMP, by doing the same for each CPU. This however
2940 * is broken.
2941 *
2942 * Imagine for instance the case where two tasks block on one CPU, only the one
2943 * CPU will have IO-wait accounted, while the other has regular idle. Even
2944 * though, if the storage were faster, both could've ran at the same time,
2945 * utilising both CPUs.
2946 *
2947 * This means, that when looking globally, the current IO-wait accounting on
2948 * SMP is a lower bound, by reason of under accounting.
2949 *
2950 * Worse, since the numbers are provided per CPU, they are sometimes
2951 * interpreted per CPU, and that is nonsensical. A blocked task isn't strictly
2952 * associated with any one particular CPU, it can wake to another CPU than it
2953 * blocked on. This means the per CPU IO-wait number is meaningless.
2954 *
2955 * Task CPU affinities can make all that even more 'interesting'.
2956 */
2957
2958unsigned long nr_iowait(void)
2959{
2960 unsigned long i, sum = 0;
2961
2962 for_each_possible_cpu(i)
2963 sum += atomic_read(&cpu_rq(i)->nr_iowait);
2964
2965 return sum;
2966}
2967
2968/*
2969 * Consumers of these two interfaces, like for example the cpufreq menu
2970 * governor are using nonsensical data. Boosting frequency for a CPU that has
2971 * IO-wait which might not even end up running the task when it does become
2972 * runnable.
2973 */
2974
2975unsigned long nr_iowait_cpu(int cpu)
2976{
2977 struct rq *this = cpu_rq(cpu);
2978 return atomic_read(&this->nr_iowait);
2979}
2980
2981void get_iowait_load(unsigned long *nr_waiters, unsigned long *load)
2982{
2983 struct rq *rq = this_rq();
2984 *nr_waiters = atomic_read(&rq->nr_iowait);
2985 *load = rq->load.weight;
2986}
2987
2988#ifdef CONFIG_SMP
2989
2990/*
2991 * sched_exec - execve() is a valuable balancing opportunity, because at
2992 * this point the task has the smallest effective memory and cache footprint.
2993 */
2994void sched_exec(void)
2995{
2996 struct task_struct *p = current;
2997 unsigned long flags;
2998 int dest_cpu;
2999
3000 raw_spin_lock_irqsave(&p->pi_lock, flags);
3001 dest_cpu = p->sched_class->select_task_rq(p, task_cpu(p), SD_BALANCE_EXEC, 0);
3002 if (dest_cpu == smp_processor_id())
3003 goto unlock;
3004
3005 if (likely(cpu_active(dest_cpu))) {
3006 struct migration_arg arg = { p, dest_cpu };
3007
3008 raw_spin_unlock_irqrestore(&p->pi_lock, flags);
3009 stop_one_cpu(task_cpu(p), migration_cpu_stop, &arg);
3010 return;
3011 }
3012unlock:
3013 raw_spin_unlock_irqrestore(&p->pi_lock, flags);
3014}
3015
3016#endif
3017
3018DEFINE_PER_CPU(struct kernel_stat, kstat);
3019DEFINE_PER_CPU(struct kernel_cpustat, kernel_cpustat);
3020
3021EXPORT_PER_CPU_SYMBOL(kstat);
3022EXPORT_PER_CPU_SYMBOL(kernel_cpustat);
3023
3024/*
3025 * The function fair_sched_class.update_curr accesses the struct curr
3026 * and its field curr->exec_start; when called from task_sched_runtime(),
3027 * we observe a high rate of cache misses in practice.
3028 * Prefetching this data results in improved performance.
3029 */
3030static inline void prefetch_curr_exec_start(struct task_struct *p)
3031{
3032#ifdef CONFIG_FAIR_GROUP_SCHED
3033 struct sched_entity *curr = (&p->se)->cfs_rq->curr;
3034#else
3035 struct sched_entity *curr = (&task_rq(p)->cfs)->curr;
3036#endif
3037 prefetch(curr);
3038 prefetch(&curr->exec_start);
3039}
3040
3041/*
3042 * Return accounted runtime for the task.
3043 * In case the task is currently running, return the runtime plus current's
3044 * pending runtime that have not been accounted yet.
3045 */
3046unsigned long long task_sched_runtime(struct task_struct *p)
3047{
3048 struct rq_flags rf;
3049 struct rq *rq;
3050 u64 ns;
3051
3052#if defined(CONFIG_64BIT) && defined(CONFIG_SMP)
3053 /*
3054 * 64-bit doesn't need locks to atomically read a 64-bit value.
3055 * So we have a optimization chance when the task's delta_exec is 0.
3056 * Reading ->on_cpu is racy, but this is ok.
3057 *
3058 * If we race with it leaving CPU, we'll take a lock. So we're correct.
3059 * If we race with it entering CPU, unaccounted time is 0. This is
3060 * indistinguishable from the read occurring a few cycles earlier.
3061 * If we see ->on_cpu without ->on_rq, the task is leaving, and has
3062 * been accounted, so we're correct here as well.
3063 */
3064 if (!p->on_cpu || !task_on_rq_queued(p))
3065 return p->se.sum_exec_runtime;
3066#endif
3067
3068 rq = task_rq_lock(p, &rf);
3069 /*
3070 * Must be ->curr _and_ ->on_rq. If dequeued, we would
3071 * project cycles that may never be accounted to this
3072 * thread, breaking clock_gettime().
3073 */
3074 if (task_current(rq, p) && task_on_rq_queued(p)) {
3075 prefetch_curr_exec_start(p);
3076 update_rq_clock(rq);
3077 p->sched_class->update_curr(rq);
3078 }
3079 ns = p->se.sum_exec_runtime;
3080 task_rq_unlock(rq, p, &rf);
3081
3082 return ns;
3083}
3084
3085/*
3086 * This function gets called by the timer code, with HZ frequency.
3087 * We call it with interrupts disabled.
3088 */
3089void scheduler_tick(void)
3090{
3091 int cpu = smp_processor_id();
3092 struct rq *rq = cpu_rq(cpu);
3093 struct task_struct *curr = rq->curr;
3094 struct rq_flags rf;
3095
3096 sched_clock_tick();
3097
3098 rq_lock(rq, &rf);
3099
3100 update_rq_clock(rq);
3101 curr->sched_class->task_tick(rq, curr, 0);
3102 cpu_load_update_active(rq);
3103 calc_global_load_tick(rq);
3104
3105 rq_unlock(rq, &rf);
3106
3107 perf_event_task_tick();
3108
3109#ifdef CONFIG_SMP
3110 rq->idle_balance = idle_cpu(cpu);
3111 trigger_load_balance(rq);
3112#endif
3113}
3114
3115#ifdef CONFIG_NO_HZ_FULL
3116
3117struct tick_work {
3118 int cpu;
3119 struct delayed_work work;
3120};
3121
3122static struct tick_work __percpu *tick_work_cpu;
3123
3124static void sched_tick_remote(struct work_struct *work)
3125{
3126 struct delayed_work *dwork = to_delayed_work(work);
3127 struct tick_work *twork = container_of(dwork, struct tick_work, work);
3128 int cpu = twork->cpu;
3129 struct rq *rq = cpu_rq(cpu);
3130 struct rq_flags rf;
3131
3132 /*
3133 * Handle the tick only if it appears the remote CPU is running in full
3134 * dynticks mode. The check is racy by nature, but missing a tick or
3135 * having one too much is no big deal because the scheduler tick updates
3136 * statistics and checks timeslices in a time-independent way, regardless
3137 * of when exactly it is running.
3138 */
3139 if (!idle_cpu(cpu) && tick_nohz_tick_stopped_cpu(cpu)) {
3140 struct task_struct *curr;
3141 u64 delta;
3142
3143 rq_lock_irq(rq, &rf);
3144 update_rq_clock(rq);
3145 curr = rq->curr;
3146 delta = rq_clock_task(rq) - curr->se.exec_start;
3147
3148 /*
3149 * Make sure the next tick runs within a reasonable
3150 * amount of time.
3151 */
3152 WARN_ON_ONCE(delta > (u64)NSEC_PER_SEC * 3);
3153 curr->sched_class->task_tick(rq, curr, 0);
3154 rq_unlock_irq(rq, &rf);
3155 }
3156
3157 /*
3158 * Run the remote tick once per second (1Hz). This arbitrary
3159 * frequency is large enough to avoid overload but short enough
3160 * to keep scheduler internal stats reasonably up to date.
3161 */
3162 queue_delayed_work(system_unbound_wq, dwork, HZ);
3163}
3164
3165static void sched_tick_start(int cpu)
3166{
3167 struct tick_work *twork;
3168
3169 if (housekeeping_cpu(cpu, HK_FLAG_TICK))
3170 return;
3171
3172 WARN_ON_ONCE(!tick_work_cpu);
3173
3174 twork = per_cpu_ptr(tick_work_cpu, cpu);
3175 twork->cpu = cpu;
3176 INIT_DELAYED_WORK(&twork->work, sched_tick_remote);
3177 queue_delayed_work(system_unbound_wq, &twork->work, HZ);
3178}
3179
3180#ifdef CONFIG_HOTPLUG_CPU
3181static void sched_tick_stop(int cpu)
3182{
3183 struct tick_work *twork;
3184
3185 if (housekeeping_cpu(cpu, HK_FLAG_TICK))
3186 return;
3187
3188 WARN_ON_ONCE(!tick_work_cpu);
3189
3190 twork = per_cpu_ptr(tick_work_cpu, cpu);
3191 cancel_delayed_work_sync(&twork->work);
3192}
3193#endif /* CONFIG_HOTPLUG_CPU */
3194
3195int __init sched_tick_offload_init(void)
3196{
3197 tick_work_cpu = alloc_percpu(struct tick_work);
3198 BUG_ON(!tick_work_cpu);
3199
3200 return 0;
3201}
3202
3203#else /* !CONFIG_NO_HZ_FULL */
3204static inline void sched_tick_start(int cpu) { }
3205static inline void sched_tick_stop(int cpu) { }
3206#endif
3207
3208#if defined(CONFIG_PREEMPT) && (defined(CONFIG_DEBUG_PREEMPT) || \
3209 defined(CONFIG_PREEMPT_TRACER))
3210/*
3211 * If the value passed in is equal to the current preempt count
3212 * then we just disabled preemption. Start timing the latency.
3213 */
3214static inline void preempt_latency_start(int val)
3215{
3216 if (preempt_count() == val) {
3217 unsigned long ip = get_lock_parent_ip();
3218#ifdef CONFIG_DEBUG_PREEMPT
3219 current->preempt_disable_ip = ip;
3220#endif
3221 trace_preempt_off(CALLER_ADDR0, ip);
3222 }
3223}
3224
3225void preempt_count_add(int val)
3226{
3227#ifdef CONFIG_DEBUG_PREEMPT
3228 /*
3229 * Underflow?
3230 */
3231 if (DEBUG_LOCKS_WARN_ON((preempt_count() < 0)))
3232 return;
3233#endif
3234 __preempt_count_add(val);
3235#ifdef CONFIG_DEBUG_PREEMPT
3236 /*
3237 * Spinlock count overflowing soon?
3238 */
3239 DEBUG_LOCKS_WARN_ON((preempt_count() & PREEMPT_MASK) >=
3240 PREEMPT_MASK - 10);
3241#endif
3242 preempt_latency_start(val);
3243}
3244EXPORT_SYMBOL(preempt_count_add);
3245NOKPROBE_SYMBOL(preempt_count_add);
3246
3247/*
3248 * If the value passed in equals to the current preempt count
3249 * then we just enabled preemption. Stop timing the latency.
3250 */
3251static inline void preempt_latency_stop(int val)
3252{
3253 if (preempt_count() == val)
3254 trace_preempt_on(CALLER_ADDR0, get_lock_parent_ip());
3255}
3256
3257void preempt_count_sub(int val)
3258{
3259#ifdef CONFIG_DEBUG_PREEMPT
3260 /*
3261 * Underflow?
3262 */
3263 if (DEBUG_LOCKS_WARN_ON(val > preempt_count()))
3264 return;
3265 /*
3266 * Is the spinlock portion underflowing?
3267 */
3268 if (DEBUG_LOCKS_WARN_ON((val < PREEMPT_MASK) &&
3269 !(preempt_count() & PREEMPT_MASK)))
3270 return;
3271#endif
3272
3273 preempt_latency_stop(val);
3274 __preempt_count_sub(val);
3275}
3276EXPORT_SYMBOL(preempt_count_sub);
3277NOKPROBE_SYMBOL(preempt_count_sub);
3278
3279#else
3280static inline void preempt_latency_start(int val) { }
3281static inline void preempt_latency_stop(int val) { }
3282#endif
3283
3284static inline unsigned long get_preempt_disable_ip(struct task_struct *p)
3285{
3286#ifdef CONFIG_DEBUG_PREEMPT
3287 return p->preempt_disable_ip;
3288#else
3289 return 0;
3290#endif
3291}
3292
3293/*
3294 * Print scheduling while atomic bug:
3295 */
3296static noinline void __schedule_bug(struct task_struct *prev)
3297{
3298 /* Save this before calling printk(), since that will clobber it */
3299 unsigned long preempt_disable_ip = get_preempt_disable_ip(current);
3300
3301 if (oops_in_progress)
3302 return;
3303
3304 printk(KERN_ERR "BUG: scheduling while atomic: %s/%d/0x%08x\n",
3305 prev->comm, prev->pid, preempt_count());
3306
3307 debug_show_held_locks(prev);
3308 print_modules();
3309 if (irqs_disabled())
3310 print_irqtrace_events(prev);
3311 if (IS_ENABLED(CONFIG_DEBUG_PREEMPT)
3312 && in_atomic_preempt_off()) {
3313 pr_err("Preemption disabled at:");
3314 print_ip_sym(preempt_disable_ip);
3315 pr_cont("\n");
3316 }
3317 if (panic_on_warn)
3318 panic("scheduling while atomic\n");
3319
3320 dump_stack();
3321 add_taint(TAINT_WARN, LOCKDEP_STILL_OK);
3322}
3323
3324/*
3325 * Various schedule()-time debugging checks and statistics:
3326 */
3327static inline void schedule_debug(struct task_struct *prev)
3328{
3329#ifdef CONFIG_SCHED_STACK_END_CHECK
3330 if (task_stack_end_corrupted(prev))
3331 panic("corrupted stack end detected inside scheduler\n");
3332#endif
3333
3334 if (unlikely(in_atomic_preempt_off())) {
3335 __schedule_bug(prev);
3336 preempt_count_set(PREEMPT_DISABLED);
3337 }
3338 rcu_sleep_check();
3339
3340 profile_hit(SCHED_PROFILING, __builtin_return_address(0));
3341
3342 schedstat_inc(this_rq()->sched_count);
3343}
3344
3345/*
3346 * Pick up the highest-prio task:
3347 */
3348static inline struct task_struct *
3349pick_next_task(struct rq *rq, struct task_struct *prev, struct rq_flags *rf)
3350{
3351 const struct sched_class *class;
3352 struct task_struct *p;
3353
3354 /*
3355 * Optimization: we know that if all tasks are in the fair class we can
3356 * call that function directly, but only if the @prev task wasn't of a
3357 * higher scheduling class, because otherwise those loose the
3358 * opportunity to pull in more work from other CPUs.
3359 */
3360 if (likely((prev->sched_class == &idle_sched_class ||
3361 prev->sched_class == &fair_sched_class) &&
3362 rq->nr_running == rq->cfs.h_nr_running)) {
3363
3364 p = fair_sched_class.pick_next_task(rq, prev, rf);
3365 if (unlikely(p == RETRY_TASK))
3366 goto again;
3367
3368 /* Assumes fair_sched_class->next == idle_sched_class */
3369 if (unlikely(!p))
3370 p = idle_sched_class.pick_next_task(rq, prev, rf);
3371
3372 return p;
3373 }
3374
3375again:
3376 for_each_class(class) {
3377 p = class->pick_next_task(rq, prev, rf);
3378 if (p) {
3379 if (unlikely(p == RETRY_TASK))
3380 goto again;
3381 return p;
3382 }
3383 }
3384
3385 /* The idle class should always have a runnable task: */
3386 BUG();
3387}
3388
3389/*
3390 * __schedule() is the main scheduler function.
3391 *
3392 * The main means of driving the scheduler and thus entering this function are:
3393 *
3394 * 1. Explicit blocking: mutex, semaphore, waitqueue, etc.
3395 *
3396 * 2. TIF_NEED_RESCHED flag is checked on interrupt and userspace return
3397 * paths. For example, see arch/x86/entry_64.S.
3398 *
3399 * To drive preemption between tasks, the scheduler sets the flag in timer
3400 * interrupt handler scheduler_tick().
3401 *
3402 * 3. Wakeups don't really cause entry into schedule(). They add a
3403 * task to the run-queue and that's it.
3404 *
3405 * Now, if the new task added to the run-queue preempts the current
3406 * task, then the wakeup sets TIF_NEED_RESCHED and schedule() gets
3407 * called on the nearest possible occasion:
3408 *
3409 * - If the kernel is preemptible (CONFIG_PREEMPT=y):
3410 *
3411 * - in syscall or exception context, at the next outmost
3412 * preempt_enable(). (this might be as soon as the wake_up()'s
3413 * spin_unlock()!)
3414 *
3415 * - in IRQ context, return from interrupt-handler to
3416 * preemptible context
3417 *
3418 * - If the kernel is not preemptible (CONFIG_PREEMPT is not set)
3419 * then at the next:
3420 *
3421 * - cond_resched() call
3422 * - explicit schedule() call
3423 * - return from syscall or exception to user-space
3424 * - return from interrupt-handler to user-space
3425 *
3426 * WARNING: must be called with preemption disabled!
3427 */
3428static void __sched notrace __schedule(bool preempt)
3429{
3430 struct task_struct *prev, *next;
3431 unsigned long *switch_count;
3432 struct rq_flags rf;
3433 struct rq *rq;
3434 int cpu;
3435
3436 cpu = smp_processor_id();
3437 rq = cpu_rq(cpu);
3438 prev = rq->curr;
3439
3440 schedule_debug(prev);
3441
3442 if (sched_feat(HRTICK))
3443 hrtick_clear(rq);
3444
3445 local_irq_disable();
3446 rcu_note_context_switch(preempt);
3447
3448 /*
3449 * Make sure that signal_pending_state()->signal_pending() below
3450 * can't be reordered with __set_current_state(TASK_INTERRUPTIBLE)
3451 * done by the caller to avoid the race with signal_wake_up().
3452 *
3453 * The membarrier system call requires a full memory barrier
3454 * after coming from user-space, before storing to rq->curr.
3455 */
3456 rq_lock(rq, &rf);
3457 smp_mb__after_spinlock();
3458
3459 /* Promote REQ to ACT */
3460 rq->clock_update_flags <<= 1;
3461 update_rq_clock(rq);
3462
3463 switch_count = &prev->nivcsw;
3464 if (!preempt && prev->state) {
3465 if (unlikely(signal_pending_state(prev->state, prev))) {
3466 prev->state = TASK_RUNNING;
3467 } else {
3468 deactivate_task(rq, prev, DEQUEUE_SLEEP | DEQUEUE_NOCLOCK);
3469 prev->on_rq = 0;
3470
3471 if (prev->in_iowait) {
3472 atomic_inc(&rq->nr_iowait);
3473 delayacct_blkio_start();
3474 }
3475
3476 /*
3477 * If a worker went to sleep, notify and ask workqueue
3478 * whether it wants to wake up a task to maintain
3479 * concurrency.
3480 */
3481 if (prev->flags & PF_WQ_WORKER) {
3482 struct task_struct *to_wakeup;
3483
3484 to_wakeup = wq_worker_sleeping(prev);
3485 if (to_wakeup)
3486 try_to_wake_up_local(to_wakeup, &rf);
3487 }
3488 }
3489 switch_count = &prev->nvcsw;
3490 }
3491
3492 next = pick_next_task(rq, prev, &rf);
3493 clear_tsk_need_resched(prev);
3494 clear_preempt_need_resched();
3495
3496 if (likely(prev != next)) {
3497 rq->nr_switches++;
3498 rq->curr = next;
3499 /*
3500 * The membarrier system call requires each architecture
3501 * to have a full memory barrier after updating
3502 * rq->curr, before returning to user-space.
3503 *
3504 * Here are the schemes providing that barrier on the
3505 * various architectures:
3506 * - mm ? switch_mm() : mmdrop() for x86, s390, sparc, PowerPC.
3507 * switch_mm() rely on membarrier_arch_switch_mm() on PowerPC.
3508 * - finish_lock_switch() for weakly-ordered
3509 * architectures where spin_unlock is a full barrier,
3510 * - switch_to() for arm64 (weakly-ordered, spin_unlock
3511 * is a RELEASE barrier),
3512 */
3513 ++*switch_count;
3514
3515 trace_sched_switch(preempt, prev, next);
3516
3517 /* Also unlocks the rq: */
3518 rq = context_switch(rq, prev, next, &rf);
3519 } else {
3520 rq->clock_update_flags &= ~(RQCF_ACT_SKIP|RQCF_REQ_SKIP);
3521 rq_unlock_irq(rq, &rf);
3522 }
3523
3524 balance_callback(rq);
3525}
3526
3527void __noreturn do_task_dead(void)
3528{
3529 /* Causes final put_task_struct in finish_task_switch(): */
3530 set_special_state(TASK_DEAD);
3531
3532 /* Tell freezer to ignore us: */
3533 current->flags |= PF_NOFREEZE;
3534
3535 __schedule(false);
3536 BUG();
3537
3538 /* Avoid "noreturn function does return" - but don't continue if BUG() is a NOP: */
3539 for (;;)
3540 cpu_relax();
3541}
3542
3543static inline void sched_submit_work(struct task_struct *tsk)
3544{
3545 if (!tsk->state || tsk_is_pi_blocked(tsk))
3546 return;
3547 /*
3548 * If we are going to sleep and we have plugged IO queued,
3549 * make sure to submit it to avoid deadlocks.
3550 */
3551 if (blk_needs_flush_plug(tsk))
3552 blk_schedule_flush_plug(tsk);
3553}
3554
3555asmlinkage __visible void __sched schedule(void)
3556{
3557 struct task_struct *tsk = current;
3558
3559 sched_submit_work(tsk);
3560 do {
3561 preempt_disable();
3562 __schedule(false);
3563 sched_preempt_enable_no_resched();
3564 } while (need_resched());
3565}
3566EXPORT_SYMBOL(schedule);
3567
3568/*
3569 * synchronize_rcu_tasks() makes sure that no task is stuck in preempted
3570 * state (have scheduled out non-voluntarily) by making sure that all
3571 * tasks have either left the run queue or have gone into user space.
3572 * As idle tasks do not do either, they must not ever be preempted
3573 * (schedule out non-voluntarily).
3574 *
3575 * schedule_idle() is similar to schedule_preempt_disable() except that it
3576 * never enables preemption because it does not call sched_submit_work().
3577 */
3578void __sched schedule_idle(void)
3579{
3580 /*
3581 * As this skips calling sched_submit_work(), which the idle task does
3582 * regardless because that function is a nop when the task is in a
3583 * TASK_RUNNING state, make sure this isn't used someplace that the
3584 * current task can be in any other state. Note, idle is always in the
3585 * TASK_RUNNING state.
3586 */
3587 WARN_ON_ONCE(current->state);
3588 do {
3589 __schedule(false);
3590 } while (need_resched());
3591}
3592
3593#ifdef CONFIG_CONTEXT_TRACKING
3594asmlinkage __visible void __sched schedule_user(void)
3595{
3596 /*
3597 * If we come here after a random call to set_need_resched(),
3598 * or we have been woken up remotely but the IPI has not yet arrived,
3599 * we haven't yet exited the RCU idle mode. Do it here manually until
3600 * we find a better solution.
3601 *
3602 * NB: There are buggy callers of this function. Ideally we
3603 * should warn if prev_state != CONTEXT_USER, but that will trigger
3604 * too frequently to make sense yet.
3605 */
3606 enum ctx_state prev_state = exception_enter();
3607 schedule();
3608 exception_exit(prev_state);
3609}
3610#endif
3611
3612/**
3613 * schedule_preempt_disabled - called with preemption disabled
3614 *
3615 * Returns with preemption disabled. Note: preempt_count must be 1
3616 */
3617void __sched schedule_preempt_disabled(void)
3618{
3619 sched_preempt_enable_no_resched();
3620 schedule();
3621 preempt_disable();
3622}
3623
3624static void __sched notrace preempt_schedule_common(void)
3625{
3626 do {
3627 /*
3628 * Because the function tracer can trace preempt_count_sub()
3629 * and it also uses preempt_enable/disable_notrace(), if
3630 * NEED_RESCHED is set, the preempt_enable_notrace() called
3631 * by the function tracer will call this function again and
3632 * cause infinite recursion.
3633 *
3634 * Preemption must be disabled here before the function
3635 * tracer can trace. Break up preempt_disable() into two
3636 * calls. One to disable preemption without fear of being
3637 * traced. The other to still record the preemption latency,
3638 * which can also be traced by the function tracer.
3639 */
3640 preempt_disable_notrace();
3641 preempt_latency_start(1);
3642 __schedule(true);
3643 preempt_latency_stop(1);
3644 preempt_enable_no_resched_notrace();
3645
3646 /*
3647 * Check again in case we missed a preemption opportunity
3648 * between schedule and now.
3649 */
3650 } while (need_resched());
3651}
3652
3653#ifdef CONFIG_PREEMPT
3654/*
3655 * this is the entry point to schedule() from in-kernel preemption
3656 * off of preempt_enable. Kernel preemptions off return from interrupt
3657 * occur there and call schedule directly.
3658 */
3659asmlinkage __visible void __sched notrace preempt_schedule(void)
3660{
3661 /*
3662 * If there is a non-zero preempt_count or interrupts are disabled,
3663 * we do not want to preempt the current task. Just return..
3664 */
3665 if (likely(!preemptible()))
3666 return;
3667
3668 preempt_schedule_common();
3669}
3670NOKPROBE_SYMBOL(preempt_schedule);
3671EXPORT_SYMBOL(preempt_schedule);
3672
3673/**
3674 * preempt_schedule_notrace - preempt_schedule called by tracing
3675 *
3676 * The tracing infrastructure uses preempt_enable_notrace to prevent
3677 * recursion and tracing preempt enabling caused by the tracing
3678 * infrastructure itself. But as tracing can happen in areas coming
3679 * from userspace or just about to enter userspace, a preempt enable
3680 * can occur before user_exit() is called. This will cause the scheduler
3681 * to be called when the system is still in usermode.
3682 *
3683 * To prevent this, the preempt_enable_notrace will use this function
3684 * instead of preempt_schedule() to exit user context if needed before
3685 * calling the scheduler.
3686 */
3687asmlinkage __visible void __sched notrace preempt_schedule_notrace(void)
3688{
3689 enum ctx_state prev_ctx;
3690
3691 if (likely(!preemptible()))
3692 return;
3693
3694 do {
3695 /*
3696 * Because the function tracer can trace preempt_count_sub()
3697 * and it also uses preempt_enable/disable_notrace(), if
3698 * NEED_RESCHED is set, the preempt_enable_notrace() called
3699 * by the function tracer will call this function again and
3700 * cause infinite recursion.
3701 *
3702 * Preemption must be disabled here before the function
3703 * tracer can trace. Break up preempt_disable() into two
3704 * calls. One to disable preemption without fear of being
3705 * traced. The other to still record the preemption latency,
3706 * which can also be traced by the function tracer.
3707 */
3708 preempt_disable_notrace();
3709 preempt_latency_start(1);
3710 /*
3711 * Needs preempt disabled in case user_exit() is traced
3712 * and the tracer calls preempt_enable_notrace() causing
3713 * an infinite recursion.
3714 */
3715 prev_ctx = exception_enter();
3716 __schedule(true);
3717 exception_exit(prev_ctx);
3718
3719 preempt_latency_stop(1);
3720 preempt_enable_no_resched_notrace();
3721 } while (need_resched());
3722}
3723EXPORT_SYMBOL_GPL(preempt_schedule_notrace);
3724
3725#endif /* CONFIG_PREEMPT */
3726
3727/*
3728 * this is the entry point to schedule() from kernel preemption
3729 * off of irq context.
3730 * Note, that this is called and return with irqs disabled. This will
3731 * protect us against recursive calling from irq.
3732 */
3733asmlinkage __visible void __sched preempt_schedule_irq(void)
3734{
3735 enum ctx_state prev_state;
3736
3737 /* Catch callers which need to be fixed */
3738 BUG_ON(preempt_count() || !irqs_disabled());
3739
3740 prev_state = exception_enter();
3741
3742 do {
3743 preempt_disable();
3744 local_irq_enable();
3745 __schedule(true);
3746 local_irq_disable();
3747 sched_preempt_enable_no_resched();
3748 } while (need_resched());
3749
3750 exception_exit(prev_state);
3751}
3752
3753int default_wake_function(wait_queue_entry_t *curr, unsigned mode, int wake_flags,
3754 void *key)
3755{
3756 return try_to_wake_up(curr->private, mode, wake_flags);
3757}
3758EXPORT_SYMBOL(default_wake_function);
3759
3760#ifdef CONFIG_RT_MUTEXES
3761
3762static inline int __rt_effective_prio(struct task_struct *pi_task, int prio)
3763{
3764 if (pi_task)
3765 prio = min(prio, pi_task->prio);
3766
3767 return prio;
3768}
3769
3770static inline int rt_effective_prio(struct task_struct *p, int prio)
3771{
3772 struct task_struct *pi_task = rt_mutex_get_top_task(p);
3773
3774 return __rt_effective_prio(pi_task, prio);
3775}
3776
3777/*
3778 * rt_mutex_setprio - set the current priority of a task
3779 * @p: task to boost
3780 * @pi_task: donor task
3781 *
3782 * This function changes the 'effective' priority of a task. It does
3783 * not touch ->normal_prio like __setscheduler().
3784 *
3785 * Used by the rt_mutex code to implement priority inheritance
3786 * logic. Call site only calls if the priority of the task changed.
3787 */
3788void rt_mutex_setprio(struct task_struct *p, struct task_struct *pi_task)
3789{
3790 int prio, oldprio, queued, running, queue_flag =
3791 DEQUEUE_SAVE | DEQUEUE_MOVE | DEQUEUE_NOCLOCK;
3792 const struct sched_class *prev_class;
3793 struct rq_flags rf;
3794 struct rq *rq;
3795
3796 /* XXX used to be waiter->prio, not waiter->task->prio */
3797 prio = __rt_effective_prio(pi_task, p->normal_prio);
3798
3799 /*
3800 * If nothing changed; bail early.
3801 */
3802 if (p->pi_top_task == pi_task && prio == p->prio && !dl_prio(prio))
3803 return;
3804
3805 rq = __task_rq_lock(p, &rf);
3806 update_rq_clock(rq);
3807 /*
3808 * Set under pi_lock && rq->lock, such that the value can be used under
3809 * either lock.
3810 *
3811 * Note that there is loads of tricky to make this pointer cache work
3812 * right. rt_mutex_slowunlock()+rt_mutex_postunlock() work together to
3813 * ensure a task is de-boosted (pi_task is set to NULL) before the
3814 * task is allowed to run again (and can exit). This ensures the pointer
3815 * points to a blocked task -- which guaratees the task is present.
3816 */
3817 p->pi_top_task = pi_task;
3818
3819 /*
3820 * For FIFO/RR we only need to set prio, if that matches we're done.
3821 */
3822 if (prio == p->prio && !dl_prio(prio))
3823 goto out_unlock;
3824
3825 /*
3826 * Idle task boosting is a nono in general. There is one
3827 * exception, when PREEMPT_RT and NOHZ is active:
3828 *
3829 * The idle task calls get_next_timer_interrupt() and holds
3830 * the timer wheel base->lock on the CPU and another CPU wants
3831 * to access the timer (probably to cancel it). We can safely
3832 * ignore the boosting request, as the idle CPU runs this code
3833 * with interrupts disabled and will complete the lock
3834 * protected section without being interrupted. So there is no
3835 * real need to boost.
3836 */
3837 if (unlikely(p == rq->idle)) {
3838 WARN_ON(p != rq->curr);
3839 WARN_ON(p->pi_blocked_on);
3840 goto out_unlock;
3841 }
3842
3843 trace_sched_pi_setprio(p, pi_task);
3844 oldprio = p->prio;
3845
3846 if (oldprio == prio)
3847 queue_flag &= ~DEQUEUE_MOVE;
3848
3849 prev_class = p->sched_class;
3850 queued = task_on_rq_queued(p);
3851 running = task_current(rq, p);
3852 if (queued)
3853 dequeue_task(rq, p, queue_flag);
3854 if (running)
3855 put_prev_task(rq, p);
3856
3857 /*
3858 * Boosting condition are:
3859 * 1. -rt task is running and holds mutex A
3860 * --> -dl task blocks on mutex A
3861 *
3862 * 2. -dl task is running and holds mutex A
3863 * --> -dl task blocks on mutex A and could preempt the
3864 * running task
3865 */
3866 if (dl_prio(prio)) {
3867 if (!dl_prio(p->normal_prio) ||
3868 (pi_task && dl_entity_preempt(&pi_task->dl, &p->dl))) {
3869 p->dl.dl_boosted = 1;
3870 queue_flag |= ENQUEUE_REPLENISH;
3871 } else
3872 p->dl.dl_boosted = 0;
3873 p->sched_class = &dl_sched_class;
3874 } else if (rt_prio(prio)) {
3875 if (dl_prio(oldprio))
3876 p->dl.dl_boosted = 0;
3877 if (oldprio < prio)
3878 queue_flag |= ENQUEUE_HEAD;
3879 p->sched_class = &rt_sched_class;
3880 } else {
3881 if (dl_prio(oldprio))
3882 p->dl.dl_boosted = 0;
3883 if (rt_prio(oldprio))
3884 p->rt.timeout = 0;
3885 p->sched_class = &fair_sched_class;
3886 }
3887
3888 p->prio = prio;
3889
3890 if (queued)
3891 enqueue_task(rq, p, queue_flag);
3892 if (running)
3893 set_curr_task(rq, p);
3894
3895 check_class_changed(rq, p, prev_class, oldprio);
3896out_unlock:
3897 /* Avoid rq from going away on us: */
3898 preempt_disable();
3899 __task_rq_unlock(rq, &rf);
3900
3901 balance_callback(rq);
3902 preempt_enable();
3903}
3904#else
3905static inline int rt_effective_prio(struct task_struct *p, int prio)
3906{
3907 return prio;
3908}
3909#endif
3910
3911void set_user_nice(struct task_struct *p, long nice)
3912{
3913 bool queued, running;
3914 int old_prio, delta;
3915 struct rq_flags rf;
3916 struct rq *rq;
3917
3918 if (task_nice(p) == nice || nice < MIN_NICE || nice > MAX_NICE)
3919 return;
3920 /*
3921 * We have to be careful, if called from sys_setpriority(),
3922 * the task might be in the middle of scheduling on another CPU.
3923 */
3924 rq = task_rq_lock(p, &rf);
3925 update_rq_clock(rq);
3926
3927 /*
3928 * The RT priorities are set via sched_setscheduler(), but we still
3929 * allow the 'normal' nice value to be set - but as expected
3930 * it wont have any effect on scheduling until the task is
3931 * SCHED_DEADLINE, SCHED_FIFO or SCHED_RR:
3932 */
3933 if (task_has_dl_policy(p) || task_has_rt_policy(p)) {
3934 p->static_prio = NICE_TO_PRIO(nice);
3935 goto out_unlock;
3936 }
3937 queued = task_on_rq_queued(p);
3938 running = task_current(rq, p);
3939 if (queued)
3940 dequeue_task(rq, p, DEQUEUE_SAVE | DEQUEUE_NOCLOCK);
3941 if (running)
3942 put_prev_task(rq, p);
3943
3944 p->static_prio = NICE_TO_PRIO(nice);
3945 set_load_weight(p, true);
3946 old_prio = p->prio;
3947 p->prio = effective_prio(p);
3948 delta = p->prio - old_prio;
3949
3950 if (queued) {
3951 enqueue_task(rq, p, ENQUEUE_RESTORE | ENQUEUE_NOCLOCK);
3952 /*
3953 * If the task increased its priority or is running and
3954 * lowered its priority, then reschedule its CPU:
3955 */
3956 if (delta < 0 || (delta > 0 && task_running(rq, p)))
3957 resched_curr(rq);
3958 }
3959 if (running)
3960 set_curr_task(rq, p);
3961out_unlock:
3962 task_rq_unlock(rq, p, &rf);
3963}
3964EXPORT_SYMBOL(set_user_nice);
3965
3966/*
3967 * can_nice - check if a task can reduce its nice value
3968 * @p: task
3969 * @nice: nice value
3970 */
3971int can_nice(const struct task_struct *p, const int nice)
3972{
3973 /* Convert nice value [19,-20] to rlimit style value [1,40]: */
3974 int nice_rlim = nice_to_rlimit(nice);
3975
3976 return (nice_rlim <= task_rlimit(p, RLIMIT_NICE) ||
3977 capable(CAP_SYS_NICE));
3978}
3979
3980#ifdef __ARCH_WANT_SYS_NICE
3981
3982/*
3983 * sys_nice - change the priority of the current process.
3984 * @increment: priority increment
3985 *
3986 * sys_setpriority is a more generic, but much slower function that
3987 * does similar things.
3988 */
3989SYSCALL_DEFINE1(nice, int, increment)
3990{
3991 long nice, retval;
3992
3993 /*
3994 * Setpriority might change our priority at the same moment.
3995 * We don't have to worry. Conceptually one call occurs first
3996 * and we have a single winner.
3997 */
3998 increment = clamp(increment, -NICE_WIDTH, NICE_WIDTH);
3999 nice = task_nice(current) + increment;
4000
4001 nice = clamp_val(nice, MIN_NICE, MAX_NICE);
4002 if (increment < 0 && !can_nice(current, nice))
4003 return -EPERM;
4004
4005 retval = security_task_setnice(current, nice);
4006 if (retval)
4007 return retval;
4008
4009 set_user_nice(current, nice);
4010 return 0;
4011}
4012
4013#endif
4014
4015/**
4016 * task_prio - return the priority value of a given task.
4017 * @p: the task in question.
4018 *
4019 * Return: The priority value as seen by users in /proc.
4020 * RT tasks are offset by -200. Normal tasks are centered
4021 * around 0, value goes from -16 to +15.
4022 */
4023int task_prio(const struct task_struct *p)
4024{
4025 return p->prio - MAX_RT_PRIO;
4026}
4027
4028/**
4029 * idle_cpu - is a given CPU idle currently?
4030 * @cpu: the processor in question.
4031 *
4032 * Return: 1 if the CPU is currently idle. 0 otherwise.
4033 */
4034int idle_cpu(int cpu)
4035{
4036 struct rq *rq = cpu_rq(cpu);
4037
4038 if (rq->curr != rq->idle)
4039 return 0;
4040
4041 if (rq->nr_running)
4042 return 0;
4043
4044#ifdef CONFIG_SMP
4045 if (!llist_empty(&rq->wake_list))
4046 return 0;
4047#endif
4048
4049 return 1;
4050}
4051
4052/**
4053 * idle_task - return the idle task for a given CPU.
4054 * @cpu: the processor in question.
4055 *
4056 * Return: The idle task for the CPU @cpu.
4057 */
4058struct task_struct *idle_task(int cpu)
4059{
4060 return cpu_rq(cpu)->idle;
4061}
4062
4063/**
4064 * find_process_by_pid - find a process with a matching PID value.
4065 * @pid: the pid in question.
4066 *
4067 * The task of @pid, if found. %NULL otherwise.
4068 */
4069static struct task_struct *find_process_by_pid(pid_t pid)
4070{
4071 return pid ? find_task_by_vpid(pid) : current;
4072}
4073
4074/*
4075 * sched_setparam() passes in -1 for its policy, to let the functions
4076 * it calls know not to change it.
4077 */
4078#define SETPARAM_POLICY -1
4079
4080static void __setscheduler_params(struct task_struct *p,
4081 const struct sched_attr *attr)
4082{
4083 int policy = attr->sched_policy;
4084
4085 if (policy == SETPARAM_POLICY)
4086 policy = p->policy;
4087
4088 p->policy = policy;
4089
4090 if (dl_policy(policy))
4091 __setparam_dl(p, attr);
4092 else if (fair_policy(policy))
4093 p->static_prio = NICE_TO_PRIO(attr->sched_nice);
4094
4095 /*
4096 * __sched_setscheduler() ensures attr->sched_priority == 0 when
4097 * !rt_policy. Always setting this ensures that things like
4098 * getparam()/getattr() don't report silly values for !rt tasks.
4099 */
4100 p->rt_priority = attr->sched_priority;
4101 p->normal_prio = normal_prio(p);
4102 set_load_weight(p, true);
4103}
4104
4105/* Actually do priority change: must hold pi & rq lock. */
4106static void __setscheduler(struct rq *rq, struct task_struct *p,
4107 const struct sched_attr *attr, bool keep_boost)
4108{
4109 __setscheduler_params(p, attr);
4110
4111 /*
4112 * Keep a potential priority boosting if called from
4113 * sched_setscheduler().
4114 */
4115 p->prio = normal_prio(p);
4116 if (keep_boost)
4117 p->prio = rt_effective_prio(p, p->prio);
4118
4119 if (dl_prio(p->prio))
4120 p->sched_class = &dl_sched_class;
4121 else if (rt_prio(p->prio))
4122 p->sched_class = &rt_sched_class;
4123 else
4124 p->sched_class = &fair_sched_class;
4125}
4126
4127/*
4128 * Check the target process has a UID that matches the current process's:
4129 */
4130static bool check_same_owner(struct task_struct *p)
4131{
4132 const struct cred *cred = current_cred(), *pcred;
4133 bool match;
4134
4135 rcu_read_lock();
4136 pcred = __task_cred(p);
4137 match = (uid_eq(cred->euid, pcred->euid) ||
4138 uid_eq(cred->euid, pcred->uid));
4139 rcu_read_unlock();
4140 return match;
4141}
4142
4143static int __sched_setscheduler(struct task_struct *p,
4144 const struct sched_attr *attr,
4145 bool user, bool pi)
4146{
4147 int newprio = dl_policy(attr->sched_policy) ? MAX_DL_PRIO - 1 :
4148 MAX_RT_PRIO - 1 - attr->sched_priority;
4149 int retval, oldprio, oldpolicy = -1, queued, running;
4150 int new_effective_prio, policy = attr->sched_policy;
4151 const struct sched_class *prev_class;
4152 struct rq_flags rf;
4153 int reset_on_fork;
4154 int queue_flags = DEQUEUE_SAVE | DEQUEUE_MOVE | DEQUEUE_NOCLOCK;
4155 struct rq *rq;
4156
4157 /* The pi code expects interrupts enabled */
4158 BUG_ON(pi && in_interrupt());
4159recheck:
4160 /* Double check policy once rq lock held: */
4161 if (policy < 0) {
4162 reset_on_fork = p->sched_reset_on_fork;
4163 policy = oldpolicy = p->policy;
4164 } else {
4165 reset_on_fork = !!(attr->sched_flags & SCHED_FLAG_RESET_ON_FORK);
4166
4167 if (!valid_policy(policy))
4168 return -EINVAL;
4169 }
4170
4171 if (attr->sched_flags & ~(SCHED_FLAG_ALL | SCHED_FLAG_SUGOV))
4172 return -EINVAL;
4173
4174 /*
4175 * Valid priorities for SCHED_FIFO and SCHED_RR are
4176 * 1..MAX_USER_RT_PRIO-1, valid priority for SCHED_NORMAL,
4177 * SCHED_BATCH and SCHED_IDLE is 0.
4178 */
4179 if ((p->mm && attr->sched_priority > MAX_USER_RT_PRIO-1) ||
4180 (!p->mm && attr->sched_priority > MAX_RT_PRIO-1))
4181 return -EINVAL;
4182 if ((dl_policy(policy) && !__checkparam_dl(attr)) ||
4183 (rt_policy(policy) != (attr->sched_priority != 0)))
4184 return -EINVAL;
4185
4186 /*
4187 * Allow unprivileged RT tasks to decrease priority:
4188 */
4189 if (user && !capable(CAP_SYS_NICE)) {
4190 if (fair_policy(policy)) {
4191 if (attr->sched_nice < task_nice(p) &&
4192 !can_nice(p, attr->sched_nice))
4193 return -EPERM;
4194 }
4195
4196 if (rt_policy(policy)) {
4197 unsigned long rlim_rtprio =
4198 task_rlimit(p, RLIMIT_RTPRIO);
4199
4200 /* Can't set/change the rt policy: */
4201 if (policy != p->policy && !rlim_rtprio)
4202 return -EPERM;
4203
4204 /* Can't increase priority: */
4205 if (attr->sched_priority > p->rt_priority &&
4206 attr->sched_priority > rlim_rtprio)
4207 return -EPERM;
4208 }
4209
4210 /*
4211 * Can't set/change SCHED_DEADLINE policy at all for now
4212 * (safest behavior); in the future we would like to allow
4213 * unprivileged DL tasks to increase their relative deadline
4214 * or reduce their runtime (both ways reducing utilization)
4215 */
4216 if (dl_policy(policy))
4217 return -EPERM;
4218
4219 /*
4220 * Treat SCHED_IDLE as nice 20. Only allow a switch to
4221 * SCHED_NORMAL if the RLIMIT_NICE would normally permit it.
4222 */
4223 if (idle_policy(p->policy) && !idle_policy(policy)) {
4224 if (!can_nice(p, task_nice(p)))
4225 return -EPERM;
4226 }
4227
4228 /* Can't change other user's priorities: */
4229 if (!check_same_owner(p))
4230 return -EPERM;
4231
4232 /* Normal users shall not reset the sched_reset_on_fork flag: */
4233 if (p->sched_reset_on_fork && !reset_on_fork)
4234 return -EPERM;
4235 }
4236
4237 if (user) {
4238 if (attr->sched_flags & SCHED_FLAG_SUGOV)
4239 return -EINVAL;
4240
4241 retval = security_task_setscheduler(p);
4242 if (retval)
4243 return retval;
4244 }
4245
4246 /*
4247 * Make sure no PI-waiters arrive (or leave) while we are
4248 * changing the priority of the task:
4249 *
4250 * To be able to change p->policy safely, the appropriate
4251 * runqueue lock must be held.
4252 */
4253 rq = task_rq_lock(p, &rf);
4254 update_rq_clock(rq);
4255
4256 /*
4257 * Changing the policy of the stop threads its a very bad idea:
4258 */
4259 if (p == rq->stop) {
4260 task_rq_unlock(rq, p, &rf);
4261 return -EINVAL;
4262 }
4263
4264 /*
4265 * If not changing anything there's no need to proceed further,
4266 * but store a possible modification of reset_on_fork.
4267 */
4268 if (unlikely(policy == p->policy)) {
4269 if (fair_policy(policy) && attr->sched_nice != task_nice(p))
4270 goto change;
4271 if (rt_policy(policy) && attr->sched_priority != p->rt_priority)
4272 goto change;
4273 if (dl_policy(policy) && dl_param_changed(p, attr))
4274 goto change;
4275
4276 p->sched_reset_on_fork = reset_on_fork;
4277 task_rq_unlock(rq, p, &rf);
4278 return 0;
4279 }
4280change:
4281
4282 if (user) {
4283#ifdef CONFIG_RT_GROUP_SCHED
4284 /*
4285 * Do not allow realtime tasks into groups that have no runtime
4286 * assigned.
4287 */
4288 if (rt_bandwidth_enabled() && rt_policy(policy) &&
4289 task_group(p)->rt_bandwidth.rt_runtime == 0 &&
4290 !task_group_is_autogroup(task_group(p))) {
4291 task_rq_unlock(rq, p, &rf);
4292 return -EPERM;
4293 }
4294#endif
4295#ifdef CONFIG_SMP
4296 if (dl_bandwidth_enabled() && dl_policy(policy) &&
4297 !(attr->sched_flags & SCHED_FLAG_SUGOV)) {
4298 cpumask_t *span = rq->rd->span;
4299
4300 /*
4301 * Don't allow tasks with an affinity mask smaller than
4302 * the entire root_domain to become SCHED_DEADLINE. We
4303 * will also fail if there's no bandwidth available.
4304 */
4305 if (!cpumask_subset(span, &p->cpus_allowed) ||
4306 rq->rd->dl_bw.bw == 0) {
4307 task_rq_unlock(rq, p, &rf);
4308 return -EPERM;
4309 }
4310 }
4311#endif
4312 }
4313
4314 /* Re-check policy now with rq lock held: */
4315 if (unlikely(oldpolicy != -1 && oldpolicy != p->policy)) {
4316 policy = oldpolicy = -1;
4317 task_rq_unlock(rq, p, &rf);
4318 goto recheck;
4319 }
4320
4321 /*
4322 * If setscheduling to SCHED_DEADLINE (or changing the parameters
4323 * of a SCHED_DEADLINE task) we need to check if enough bandwidth
4324 * is available.
4325 */
4326 if ((dl_policy(policy) || dl_task(p)) && sched_dl_overflow(p, policy, attr)) {
4327 task_rq_unlock(rq, p, &rf);
4328 return -EBUSY;
4329 }
4330
4331 p->sched_reset_on_fork = reset_on_fork;
4332 oldprio = p->prio;
4333
4334 if (pi) {
4335 /*
4336 * Take priority boosted tasks into account. If the new
4337 * effective priority is unchanged, we just store the new
4338 * normal parameters and do not touch the scheduler class and
4339 * the runqueue. This will be done when the task deboost
4340 * itself.
4341 */
4342 new_effective_prio = rt_effective_prio(p, newprio);
4343 if (new_effective_prio == oldprio)
4344 queue_flags &= ~DEQUEUE_MOVE;
4345 }
4346
4347 queued = task_on_rq_queued(p);
4348 running = task_current(rq, p);
4349 if (queued)
4350 dequeue_task(rq, p, queue_flags);
4351 if (running)
4352 put_prev_task(rq, p);
4353
4354 prev_class = p->sched_class;
4355 __setscheduler(rq, p, attr, pi);
4356
4357 if (queued) {
4358 /*
4359 * We enqueue to tail when the priority of a task is
4360 * increased (user space view).
4361 */
4362 if (oldprio < p->prio)
4363 queue_flags |= ENQUEUE_HEAD;
4364
4365 enqueue_task(rq, p, queue_flags);
4366 }
4367 if (running)
4368 set_curr_task(rq, p);
4369
4370 check_class_changed(rq, p, prev_class, oldprio);
4371
4372 /* Avoid rq from going away on us: */
4373 preempt_disable();
4374 task_rq_unlock(rq, p, &rf);
4375
4376 if (pi)
4377 rt_mutex_adjust_pi(p);
4378
4379 /* Run balance callbacks after we've adjusted the PI chain: */
4380 balance_callback(rq);
4381 preempt_enable();
4382
4383 return 0;
4384}
4385
4386static int _sched_setscheduler(struct task_struct *p, int policy,
4387 const struct sched_param *param, bool check)
4388{
4389 struct sched_attr attr = {
4390 .sched_policy = policy,
4391 .sched_priority = param->sched_priority,
4392 .sched_nice = PRIO_TO_NICE(p->static_prio),
4393 };
4394
4395 /* Fixup the legacy SCHED_RESET_ON_FORK hack. */
4396 if ((policy != SETPARAM_POLICY) && (policy & SCHED_RESET_ON_FORK)) {
4397 attr.sched_flags |= SCHED_FLAG_RESET_ON_FORK;
4398 policy &= ~SCHED_RESET_ON_FORK;
4399 attr.sched_policy = policy;
4400 }
4401
4402 return __sched_setscheduler(p, &attr, check, true);
4403}
4404/**
4405 * sched_setscheduler - change the scheduling policy and/or RT priority of a thread.
4406 * @p: the task in question.
4407 * @policy: new policy.
4408 * @param: structure containing the new RT priority.
4409 *
4410 * Return: 0 on success. An error code otherwise.
4411 *
4412 * NOTE that the task may be already dead.
4413 */
4414int sched_setscheduler(struct task_struct *p, int policy,
4415 const struct sched_param *param)
4416{
4417 return _sched_setscheduler(p, policy, param, true);
4418}
4419EXPORT_SYMBOL_GPL(sched_setscheduler);
4420
4421int sched_setattr(struct task_struct *p, const struct sched_attr *attr)
4422{
4423 return __sched_setscheduler(p, attr, true, true);
4424}
4425EXPORT_SYMBOL_GPL(sched_setattr);
4426
4427int sched_setattr_nocheck(struct task_struct *p, const struct sched_attr *attr)
4428{
4429 return __sched_setscheduler(p, attr, false, true);
4430}
4431
4432/**
4433 * sched_setscheduler_nocheck - change the scheduling policy and/or RT priority of a thread from kernelspace.
4434 * @p: the task in question.
4435 * @policy: new policy.
4436 * @param: structure containing the new RT priority.
4437 *
4438 * Just like sched_setscheduler, only don't bother checking if the
4439 * current context has permission. For example, this is needed in
4440 * stop_machine(): we create temporary high priority worker threads,
4441 * but our caller might not have that capability.
4442 *
4443 * Return: 0 on success. An error code otherwise.
4444 */
4445int sched_setscheduler_nocheck(struct task_struct *p, int policy,
4446 const struct sched_param *param)
4447{
4448 return _sched_setscheduler(p, policy, param, false);
4449}
4450EXPORT_SYMBOL_GPL(sched_setscheduler_nocheck);
4451
4452static int
4453do_sched_setscheduler(pid_t pid, int policy, struct sched_param __user *param)
4454{
4455 struct sched_param lparam;
4456 struct task_struct *p;
4457 int retval;
4458
4459 if (!param || pid < 0)
4460 return -EINVAL;
4461 if (copy_from_user(&lparam, param, sizeof(struct sched_param)))
4462 return -EFAULT;
4463
4464 rcu_read_lock();
4465 retval = -ESRCH;
4466 p = find_process_by_pid(pid);
4467 if (p != NULL)
4468 retval = sched_setscheduler(p, policy, &lparam);
4469 rcu_read_unlock();
4470
4471 return retval;
4472}
4473
4474/*
4475 * Mimics kernel/events/core.c perf_copy_attr().
4476 */
4477static int sched_copy_attr(struct sched_attr __user *uattr, struct sched_attr *attr)
4478{
4479 u32 size;
4480 int ret;
4481
4482 if (!access_ok(VERIFY_WRITE, uattr, SCHED_ATTR_SIZE_VER0))
4483 return -EFAULT;
4484
4485 /* Zero the full structure, so that a short copy will be nice: */
4486 memset(attr, 0, sizeof(*attr));
4487
4488 ret = get_user(size, &uattr->size);
4489 if (ret)
4490 return ret;
4491
4492 /* Bail out on silly large: */
4493 if (size > PAGE_SIZE)
4494 goto err_size;
4495
4496 /* ABI compatibility quirk: */
4497 if (!size)
4498 size = SCHED_ATTR_SIZE_VER0;
4499
4500 if (size < SCHED_ATTR_SIZE_VER0)
4501 goto err_size;
4502
4503 /*
4504 * If we're handed a bigger struct than we know of,
4505 * ensure all the unknown bits are 0 - i.e. new
4506 * user-space does not rely on any kernel feature
4507 * extensions we dont know about yet.
4508 */
4509 if (size > sizeof(*attr)) {
4510 unsigned char __user *addr;
4511 unsigned char __user *end;
4512 unsigned char val;
4513
4514 addr = (void __user *)uattr + sizeof(*attr);
4515 end = (void __user *)uattr + size;
4516
4517 for (; addr < end; addr++) {
4518 ret = get_user(val, addr);
4519 if (ret)
4520 return ret;
4521 if (val)
4522 goto err_size;
4523 }
4524 size = sizeof(*attr);
4525 }
4526
4527 ret = copy_from_user(attr, uattr, size);
4528 if (ret)
4529 return -EFAULT;
4530
4531 /*
4532 * XXX: Do we want to be lenient like existing syscalls; or do we want
4533 * to be strict and return an error on out-of-bounds values?
4534 */
4535 attr->sched_nice = clamp(attr->sched_nice, MIN_NICE, MAX_NICE);
4536
4537 return 0;
4538
4539err_size:
4540 put_user(sizeof(*attr), &uattr->size);
4541 return -E2BIG;
4542}
4543
4544/**
4545 * sys_sched_setscheduler - set/change the scheduler policy and RT priority
4546 * @pid: the pid in question.
4547 * @policy: new policy.
4548 * @param: structure containing the new RT priority.
4549 *
4550 * Return: 0 on success. An error code otherwise.
4551 */
4552SYSCALL_DEFINE3(sched_setscheduler, pid_t, pid, int, policy, struct sched_param __user *, param)
4553{
4554 if (policy < 0)
4555 return -EINVAL;
4556
4557 return do_sched_setscheduler(pid, policy, param);
4558}
4559
4560/**
4561 * sys_sched_setparam - set/change the RT priority of a thread
4562 * @pid: the pid in question.
4563 * @param: structure containing the new RT priority.
4564 *
4565 * Return: 0 on success. An error code otherwise.
4566 */
4567SYSCALL_DEFINE2(sched_setparam, pid_t, pid, struct sched_param __user *, param)
4568{
4569 return do_sched_setscheduler(pid, SETPARAM_POLICY, param);
4570}
4571
4572/**
4573 * sys_sched_setattr - same as above, but with extended sched_attr
4574 * @pid: the pid in question.
4575 * @uattr: structure containing the extended parameters.
4576 * @flags: for future extension.
4577 */
4578SYSCALL_DEFINE3(sched_setattr, pid_t, pid, struct sched_attr __user *, uattr,
4579 unsigned int, flags)
4580{
4581 struct sched_attr attr;
4582 struct task_struct *p;
4583 int retval;
4584
4585 if (!uattr || pid < 0 || flags)
4586 return -EINVAL;
4587
4588 retval = sched_copy_attr(uattr, &attr);
4589 if (retval)
4590 return retval;
4591
4592 if ((int)attr.sched_policy < 0)
4593 return -EINVAL;
4594
4595 rcu_read_lock();
4596 retval = -ESRCH;
4597 p = find_process_by_pid(pid);
4598 if (p != NULL)
4599 retval = sched_setattr(p, &attr);
4600 rcu_read_unlock();
4601
4602 return retval;
4603}
4604
4605/**
4606 * sys_sched_getscheduler - get the policy (scheduling class) of a thread
4607 * @pid: the pid in question.
4608 *
4609 * Return: On success, the policy of the thread. Otherwise, a negative error
4610 * code.
4611 */
4612SYSCALL_DEFINE1(sched_getscheduler, pid_t, pid)
4613{
4614 struct task_struct *p;
4615 int retval;
4616
4617 if (pid < 0)
4618 return -EINVAL;
4619
4620 retval = -ESRCH;
4621 rcu_read_lock();
4622 p = find_process_by_pid(pid);
4623 if (p) {
4624 retval = security_task_getscheduler(p);
4625 if (!retval)
4626 retval = p->policy
4627 | (p->sched_reset_on_fork ? SCHED_RESET_ON_FORK : 0);
4628 }
4629 rcu_read_unlock();
4630 return retval;
4631}
4632
4633/**
4634 * sys_sched_getparam - get the RT priority of a thread
4635 * @pid: the pid in question.
4636 * @param: structure containing the RT priority.
4637 *
4638 * Return: On success, 0 and the RT priority is in @param. Otherwise, an error
4639 * code.
4640 */
4641SYSCALL_DEFINE2(sched_getparam, pid_t, pid, struct sched_param __user *, param)
4642{
4643 struct sched_param lp = { .sched_priority = 0 };
4644 struct task_struct *p;
4645 int retval;
4646
4647 if (!param || pid < 0)
4648 return -EINVAL;
4649
4650 rcu_read_lock();
4651 p = find_process_by_pid(pid);
4652 retval = -ESRCH;
4653 if (!p)
4654 goto out_unlock;
4655
4656 retval = security_task_getscheduler(p);
4657 if (retval)
4658 goto out_unlock;
4659
4660 if (task_has_rt_policy(p))
4661 lp.sched_priority = p->rt_priority;
4662 rcu_read_unlock();
4663
4664 /*
4665 * This one might sleep, we cannot do it with a spinlock held ...
4666 */
4667 retval = copy_to_user(param, &lp, sizeof(*param)) ? -EFAULT : 0;
4668
4669 return retval;
4670
4671out_unlock:
4672 rcu_read_unlock();
4673 return retval;
4674}
4675
4676static int sched_read_attr(struct sched_attr __user *uattr,
4677 struct sched_attr *attr,
4678 unsigned int usize)
4679{
4680 int ret;
4681
4682 if (!access_ok(VERIFY_WRITE, uattr, usize))
4683 return -EFAULT;
4684
4685 /*
4686 * If we're handed a smaller struct than we know of,
4687 * ensure all the unknown bits are 0 - i.e. old
4688 * user-space does not get uncomplete information.
4689 */
4690 if (usize < sizeof(*attr)) {
4691 unsigned char *addr;
4692 unsigned char *end;
4693
4694 addr = (void *)attr + usize;
4695 end = (void *)attr + sizeof(*attr);
4696
4697 for (; addr < end; addr++) {
4698 if (*addr)
4699 return -EFBIG;
4700 }
4701
4702 attr->size = usize;
4703 }
4704
4705 ret = copy_to_user(uattr, attr, attr->size);
4706 if (ret)
4707 return -EFAULT;
4708
4709 return 0;
4710}
4711
4712/**
4713 * sys_sched_getattr - similar to sched_getparam, but with sched_attr
4714 * @pid: the pid in question.
4715 * @uattr: structure containing the extended parameters.
4716 * @size: sizeof(attr) for fwd/bwd comp.
4717 * @flags: for future extension.
4718 */
4719SYSCALL_DEFINE4(sched_getattr, pid_t, pid, struct sched_attr __user *, uattr,
4720 unsigned int, size, unsigned int, flags)
4721{
4722 struct sched_attr attr = {
4723 .size = sizeof(struct sched_attr),
4724 };
4725 struct task_struct *p;
4726 int retval;
4727
4728 if (!uattr || pid < 0 || size > PAGE_SIZE ||
4729 size < SCHED_ATTR_SIZE_VER0 || flags)
4730 return -EINVAL;
4731
4732 rcu_read_lock();
4733 p = find_process_by_pid(pid);
4734 retval = -ESRCH;
4735 if (!p)
4736 goto out_unlock;
4737
4738 retval = security_task_getscheduler(p);
4739 if (retval)
4740 goto out_unlock;
4741
4742 attr.sched_policy = p->policy;
4743 if (p->sched_reset_on_fork)
4744 attr.sched_flags |= SCHED_FLAG_RESET_ON_FORK;
4745 if (task_has_dl_policy(p))
4746 __getparam_dl(p, &attr);
4747 else if (task_has_rt_policy(p))
4748 attr.sched_priority = p->rt_priority;
4749 else
4750 attr.sched_nice = task_nice(p);
4751
4752 rcu_read_unlock();
4753
4754 retval = sched_read_attr(uattr, &attr, size);
4755 return retval;
4756
4757out_unlock:
4758 rcu_read_unlock();
4759 return retval;
4760}
4761
4762long sched_setaffinity(pid_t pid, const struct cpumask *in_mask)
4763{
4764 cpumask_var_t cpus_allowed, new_mask;
4765 struct task_struct *p;
4766 int retval;
4767
4768 rcu_read_lock();
4769
4770 p = find_process_by_pid(pid);
4771 if (!p) {
4772 rcu_read_unlock();
4773 return -ESRCH;
4774 }
4775
4776 /* Prevent p going away */
4777 get_task_struct(p);
4778 rcu_read_unlock();
4779
4780 if (p->flags & PF_NO_SETAFFINITY) {
4781 retval = -EINVAL;
4782 goto out_put_task;
4783 }
4784 if (!alloc_cpumask_var(&cpus_allowed, GFP_KERNEL)) {
4785 retval = -ENOMEM;
4786 goto out_put_task;
4787 }
4788 if (!alloc_cpumask_var(&new_mask, GFP_KERNEL)) {
4789 retval = -ENOMEM;
4790 goto out_free_cpus_allowed;
4791 }
4792 retval = -EPERM;
4793 if (!check_same_owner(p)) {
4794 rcu_read_lock();
4795 if (!ns_capable(__task_cred(p)->user_ns, CAP_SYS_NICE)) {
4796 rcu_read_unlock();
4797 goto out_free_new_mask;
4798 }
4799 rcu_read_unlock();
4800 }
4801
4802 retval = security_task_setscheduler(p);
4803 if (retval)
4804 goto out_free_new_mask;
4805
4806
4807 cpuset_cpus_allowed(p, cpus_allowed);
4808 cpumask_and(new_mask, in_mask, cpus_allowed);
4809
4810 /*
4811 * Since bandwidth control happens on root_domain basis,
4812 * if admission test is enabled, we only admit -deadline
4813 * tasks allowed to run on all the CPUs in the task's
4814 * root_domain.
4815 */
4816#ifdef CONFIG_SMP
4817 if (task_has_dl_policy(p) && dl_bandwidth_enabled()) {
4818 rcu_read_lock();
4819 if (!cpumask_subset(task_rq(p)->rd->span, new_mask)) {
4820 retval = -EBUSY;
4821 rcu_read_unlock();
4822 goto out_free_new_mask;
4823 }
4824 rcu_read_unlock();
4825 }
4826#endif
4827again:
4828 retval = __set_cpus_allowed_ptr(p, new_mask, true);
4829
4830 if (!retval) {
4831 cpuset_cpus_allowed(p, cpus_allowed);
4832 if (!cpumask_subset(new_mask, cpus_allowed)) {
4833 /*
4834 * We must have raced with a concurrent cpuset
4835 * update. Just reset the cpus_allowed to the
4836 * cpuset's cpus_allowed
4837 */
4838 cpumask_copy(new_mask, cpus_allowed);
4839 goto again;
4840 }
4841 }
4842out_free_new_mask:
4843 free_cpumask_var(new_mask);
4844out_free_cpus_allowed:
4845 free_cpumask_var(cpus_allowed);
4846out_put_task:
4847 put_task_struct(p);
4848 return retval;
4849}
4850
4851static int get_user_cpu_mask(unsigned long __user *user_mask_ptr, unsigned len,
4852 struct cpumask *new_mask)
4853{
4854 if (len < cpumask_size())
4855 cpumask_clear(new_mask);
4856 else if (len > cpumask_size())
4857 len = cpumask_size();
4858
4859 return copy_from_user(new_mask, user_mask_ptr, len) ? -EFAULT : 0;
4860}
4861
4862/**
4863 * sys_sched_setaffinity - set the CPU affinity of a process
4864 * @pid: pid of the process
4865 * @len: length in bytes of the bitmask pointed to by user_mask_ptr
4866 * @user_mask_ptr: user-space pointer to the new CPU mask
4867 *
4868 * Return: 0 on success. An error code otherwise.
4869 */
4870SYSCALL_DEFINE3(sched_setaffinity, pid_t, pid, unsigned int, len,
4871 unsigned long __user *, user_mask_ptr)
4872{
4873 cpumask_var_t new_mask;
4874 int retval;
4875
4876 if (!alloc_cpumask_var(&new_mask, GFP_KERNEL))
4877 return -ENOMEM;
4878
4879 retval = get_user_cpu_mask(user_mask_ptr, len, new_mask);
4880 if (retval == 0)
4881 retval = sched_setaffinity(pid, new_mask);
4882 free_cpumask_var(new_mask);
4883 return retval;
4884}
4885
4886long sched_getaffinity(pid_t pid, struct cpumask *mask)
4887{
4888 struct task_struct *p;
4889 unsigned long flags;
4890 int retval;
4891
4892 rcu_read_lock();
4893
4894 retval = -ESRCH;
4895 p = find_process_by_pid(pid);
4896 if (!p)
4897 goto out_unlock;
4898
4899 retval = security_task_getscheduler(p);
4900 if (retval)
4901 goto out_unlock;
4902
4903 raw_spin_lock_irqsave(&p->pi_lock, flags);
4904 cpumask_and(mask, &p->cpus_allowed, cpu_active_mask);
4905 raw_spin_unlock_irqrestore(&p->pi_lock, flags);
4906
4907out_unlock:
4908 rcu_read_unlock();
4909
4910 return retval;
4911}
4912
4913/**
4914 * sys_sched_getaffinity - get the CPU affinity of a process
4915 * @pid: pid of the process
4916 * @len: length in bytes of the bitmask pointed to by user_mask_ptr
4917 * @user_mask_ptr: user-space pointer to hold the current CPU mask
4918 *
4919 * Return: size of CPU mask copied to user_mask_ptr on success. An
4920 * error code otherwise.
4921 */
4922SYSCALL_DEFINE3(sched_getaffinity, pid_t, pid, unsigned int, len,
4923 unsigned long __user *, user_mask_ptr)
4924{
4925 int ret;
4926 cpumask_var_t mask;
4927
4928 if ((len * BITS_PER_BYTE) < nr_cpu_ids)
4929 return -EINVAL;
4930 if (len & (sizeof(unsigned long)-1))
4931 return -EINVAL;
4932
4933 if (!alloc_cpumask_var(&mask, GFP_KERNEL))
4934 return -ENOMEM;
4935
4936 ret = sched_getaffinity(pid, mask);
4937 if (ret == 0) {
4938 unsigned int retlen = min(len, cpumask_size());
4939
4940 if (copy_to_user(user_mask_ptr, mask, retlen))
4941 ret = -EFAULT;
4942 else
4943 ret = retlen;
4944 }
4945 free_cpumask_var(mask);
4946
4947 return ret;
4948}
4949
4950/**
4951 * sys_sched_yield - yield the current processor to other threads.
4952 *
4953 * This function yields the current CPU to other tasks. If there are no
4954 * other threads running on this CPU then this function will return.
4955 *
4956 * Return: 0.
4957 */
4958static void do_sched_yield(void)
4959{
4960 struct rq_flags rf;
4961 struct rq *rq;
4962
4963 local_irq_disable();
4964 rq = this_rq();
4965 rq_lock(rq, &rf);
4966
4967 schedstat_inc(rq->yld_count);
4968 current->sched_class->yield_task(rq);
4969
4970 /*
4971 * Since we are going to call schedule() anyway, there's
4972 * no need to preempt or enable interrupts:
4973 */
4974 preempt_disable();
4975 rq_unlock(rq, &rf);
4976 sched_preempt_enable_no_resched();
4977
4978 schedule();
4979}
4980
4981SYSCALL_DEFINE0(sched_yield)
4982{
4983 do_sched_yield();
4984 return 0;
4985}
4986
4987#ifndef CONFIG_PREEMPT
4988int __sched _cond_resched(void)
4989{
4990 if (should_resched(0)) {
4991 preempt_schedule_common();
4992 return 1;
4993 }
4994 rcu_all_qs();
4995 return 0;
4996}
4997EXPORT_SYMBOL(_cond_resched);
4998#endif
4999
5000/*
5001 * __cond_resched_lock() - if a reschedule is pending, drop the given lock,
5002 * call schedule, and on return reacquire the lock.
5003 *
5004 * This works OK both with and without CONFIG_PREEMPT. We do strange low-level
5005 * operations here to prevent schedule() from being called twice (once via
5006 * spin_unlock(), once by hand).
5007 */
5008int __cond_resched_lock(spinlock_t *lock)
5009{
5010 int resched = should_resched(PREEMPT_LOCK_OFFSET);
5011 int ret = 0;
5012
5013 lockdep_assert_held(lock);
5014
5015 if (spin_needbreak(lock) || resched) {
5016 spin_unlock(lock);
5017 if (resched)
5018 preempt_schedule_common();
5019 else
5020 cpu_relax();
5021 ret = 1;
5022 spin_lock(lock);
5023 }
5024 return ret;
5025}
5026EXPORT_SYMBOL(__cond_resched_lock);
5027
5028int __sched __cond_resched_softirq(void)
5029{
5030 BUG_ON(!in_softirq());
5031
5032 if (should_resched(SOFTIRQ_DISABLE_OFFSET)) {
5033 local_bh_enable();
5034 preempt_schedule_common();
5035 local_bh_disable();
5036 return 1;
5037 }
5038 return 0;
5039}
5040EXPORT_SYMBOL(__cond_resched_softirq);
5041
5042/**
5043 * yield - yield the current processor to other threads.
5044 *
5045 * Do not ever use this function, there's a 99% chance you're doing it wrong.
5046 *
5047 * The scheduler is at all times free to pick the calling task as the most
5048 * eligible task to run, if removing the yield() call from your code breaks
5049 * it, its already broken.
5050 *
5051 * Typical broken usage is:
5052 *
5053 * while (!event)
5054 * yield();
5055 *
5056 * where one assumes that yield() will let 'the other' process run that will
5057 * make event true. If the current task is a SCHED_FIFO task that will never
5058 * happen. Never use yield() as a progress guarantee!!
5059 *
5060 * If you want to use yield() to wait for something, use wait_event().
5061 * If you want to use yield() to be 'nice' for others, use cond_resched().
5062 * If you still want to use yield(), do not!
5063 */
5064void __sched yield(void)
5065{
5066 set_current_state(TASK_RUNNING);
5067 do_sched_yield();
5068}
5069EXPORT_SYMBOL(yield);
5070
5071/**
5072 * yield_to - yield the current processor to another thread in
5073 * your thread group, or accelerate that thread toward the
5074 * processor it's on.
5075 * @p: target task
5076 * @preempt: whether task preemption is allowed or not
5077 *
5078 * It's the caller's job to ensure that the target task struct
5079 * can't go away on us before we can do any checks.
5080 *
5081 * Return:
5082 * true (>0) if we indeed boosted the target task.
5083 * false (0) if we failed to boost the target.
5084 * -ESRCH if there's no task to yield to.
5085 */
5086int __sched yield_to(struct task_struct *p, bool preempt)
5087{
5088 struct task_struct *curr = current;
5089 struct rq *rq, *p_rq;
5090 unsigned long flags;
5091 int yielded = 0;
5092
5093 local_irq_save(flags);
5094 rq = this_rq();
5095
5096again:
5097 p_rq = task_rq(p);
5098 /*
5099 * If we're the only runnable task on the rq and target rq also
5100 * has only one task, there's absolutely no point in yielding.
5101 */
5102 if (rq->nr_running == 1 && p_rq->nr_running == 1) {
5103 yielded = -ESRCH;
5104 goto out_irq;
5105 }
5106
5107 double_rq_lock(rq, p_rq);
5108 if (task_rq(p) != p_rq) {
5109 double_rq_unlock(rq, p_rq);
5110 goto again;
5111 }
5112
5113 if (!curr->sched_class->yield_to_task)
5114 goto out_unlock;
5115
5116 if (curr->sched_class != p->sched_class)
5117 goto out_unlock;
5118
5119 if (task_running(p_rq, p) || p->state)
5120 goto out_unlock;
5121
5122 yielded = curr->sched_class->yield_to_task(rq, p, preempt);
5123 if (yielded) {
5124 schedstat_inc(rq->yld_count);
5125 /*
5126 * Make p's CPU reschedule; pick_next_entity takes care of
5127 * fairness.
5128 */
5129 if (preempt && rq != p_rq)
5130 resched_curr(p_rq);
5131 }
5132
5133out_unlock:
5134 double_rq_unlock(rq, p_rq);
5135out_irq:
5136 local_irq_restore(flags);
5137
5138 if (yielded > 0)
5139 schedule();
5140
5141 return yielded;
5142}
5143EXPORT_SYMBOL_GPL(yield_to);
5144
5145int io_schedule_prepare(void)
5146{
5147 int old_iowait = current->in_iowait;
5148
5149 current->in_iowait = 1;
5150 blk_schedule_flush_plug(current);
5151
5152 return old_iowait;
5153}
5154
5155void io_schedule_finish(int token)
5156{
5157 current->in_iowait = token;
5158}
5159
5160/*
5161 * This task is about to go to sleep on IO. Increment rq->nr_iowait so
5162 * that process accounting knows that this is a task in IO wait state.
5163 */
5164long __sched io_schedule_timeout(long timeout)
5165{
5166 int token;
5167 long ret;
5168
5169 token = io_schedule_prepare();
5170 ret = schedule_timeout(timeout);
5171 io_schedule_finish(token);
5172
5173 return ret;
5174}
5175EXPORT_SYMBOL(io_schedule_timeout);
5176
5177void io_schedule(void)
5178{
5179 int token;
5180
5181 token = io_schedule_prepare();
5182 schedule();
5183 io_schedule_finish(token);
5184}
5185EXPORT_SYMBOL(io_schedule);
5186
5187/**
5188 * sys_sched_get_priority_max - return maximum RT priority.
5189 * @policy: scheduling class.
5190 *
5191 * Return: On success, this syscall returns the maximum
5192 * rt_priority that can be used by a given scheduling class.
5193 * On failure, a negative error code is returned.
5194 */
5195SYSCALL_DEFINE1(sched_get_priority_max, int, policy)
5196{
5197 int ret = -EINVAL;
5198
5199 switch (policy) {
5200 case SCHED_FIFO:
5201 case SCHED_RR:
5202 ret = MAX_USER_RT_PRIO-1;
5203 break;
5204 case SCHED_DEADLINE:
5205 case SCHED_NORMAL:
5206 case SCHED_BATCH:
5207 case SCHED_IDLE:
5208 ret = 0;
5209 break;
5210 }
5211 return ret;
5212}
5213
5214/**
5215 * sys_sched_get_priority_min - return minimum RT priority.
5216 * @policy: scheduling class.
5217 *
5218 * Return: On success, this syscall returns the minimum
5219 * rt_priority that can be used by a given scheduling class.
5220 * On failure, a negative error code is returned.
5221 */
5222SYSCALL_DEFINE1(sched_get_priority_min, int, policy)
5223{
5224 int ret = -EINVAL;
5225
5226 switch (policy) {
5227 case SCHED_FIFO:
5228 case SCHED_RR:
5229 ret = 1;
5230 break;
5231 case SCHED_DEADLINE:
5232 case SCHED_NORMAL:
5233 case SCHED_BATCH:
5234 case SCHED_IDLE:
5235 ret = 0;
5236 }
5237 return ret;
5238}
5239
5240static int sched_rr_get_interval(pid_t pid, struct timespec64 *t)
5241{
5242 struct task_struct *p;
5243 unsigned int time_slice;
5244 struct rq_flags rf;
5245 struct rq *rq;
5246 int retval;
5247
5248 if (pid < 0)
5249 return -EINVAL;
5250
5251 retval = -ESRCH;
5252 rcu_read_lock();
5253 p = find_process_by_pid(pid);
5254 if (!p)
5255 goto out_unlock;
5256
5257 retval = security_task_getscheduler(p);
5258 if (retval)
5259 goto out_unlock;
5260
5261 rq = task_rq_lock(p, &rf);
5262 time_slice = 0;
5263 if (p->sched_class->get_rr_interval)
5264 time_slice = p->sched_class->get_rr_interval(rq, p);
5265 task_rq_unlock(rq, p, &rf);
5266
5267 rcu_read_unlock();
5268 jiffies_to_timespec64(time_slice, t);
5269 return 0;
5270
5271out_unlock:
5272 rcu_read_unlock();
5273 return retval;
5274}
5275
5276/**
5277 * sys_sched_rr_get_interval - return the default timeslice of a process.
5278 * @pid: pid of the process.
5279 * @interval: userspace pointer to the timeslice value.
5280 *
5281 * this syscall writes the default timeslice value of a given process
5282 * into the user-space timespec buffer. A value of '0' means infinity.
5283 *
5284 * Return: On success, 0 and the timeslice is in @interval. Otherwise,
5285 * an error code.
5286 */
5287SYSCALL_DEFINE2(sched_rr_get_interval, pid_t, pid,
5288 struct timespec __user *, interval)
5289{
5290 struct timespec64 t;
5291 int retval = sched_rr_get_interval(pid, &t);
5292
5293 if (retval == 0)
5294 retval = put_timespec64(&t, interval);
5295
5296 return retval;
5297}
5298
5299#ifdef CONFIG_COMPAT
5300COMPAT_SYSCALL_DEFINE2(sched_rr_get_interval,
5301 compat_pid_t, pid,
5302 struct compat_timespec __user *, interval)
5303{
5304 struct timespec64 t;
5305 int retval = sched_rr_get_interval(pid, &t);
5306
5307 if (retval == 0)
5308 retval = compat_put_timespec64(&t, interval);
5309 return retval;
5310}
5311#endif
5312
5313void sched_show_task(struct task_struct *p)
5314{
5315 unsigned long free = 0;
5316 int ppid;
5317
5318 if (!try_get_task_stack(p))
5319 return;
5320
5321 printk(KERN_INFO "%-15.15s %c", p->comm, task_state_to_char(p));
5322
5323 if (p->state == TASK_RUNNING)
5324 printk(KERN_CONT " running task ");
5325#ifdef CONFIG_DEBUG_STACK_USAGE
5326 free = stack_not_used(p);
5327#endif
5328 ppid = 0;
5329 rcu_read_lock();
5330 if (pid_alive(p))
5331 ppid = task_pid_nr(rcu_dereference(p->real_parent));
5332 rcu_read_unlock();
5333 printk(KERN_CONT "%5lu %5d %6d 0x%08lx\n", free,
5334 task_pid_nr(p), ppid,
5335 (unsigned long)task_thread_info(p)->flags);
5336
5337 print_worker_info(KERN_INFO, p);
5338 show_stack(p, NULL);
5339 put_task_stack(p);
5340}
5341EXPORT_SYMBOL_GPL(sched_show_task);
5342
5343static inline bool
5344state_filter_match(unsigned long state_filter, struct task_struct *p)
5345{
5346 /* no filter, everything matches */
5347 if (!state_filter)
5348 return true;
5349
5350 /* filter, but doesn't match */
5351 if (!(p->state & state_filter))
5352 return false;
5353
5354 /*
5355 * When looking for TASK_UNINTERRUPTIBLE skip TASK_IDLE (allows
5356 * TASK_KILLABLE).
5357 */
5358 if (state_filter == TASK_UNINTERRUPTIBLE && p->state == TASK_IDLE)
5359 return false;
5360
5361 return true;
5362}
5363
5364
5365void show_state_filter(unsigned long state_filter)
5366{
5367 struct task_struct *g, *p;
5368
5369#if BITS_PER_LONG == 32
5370 printk(KERN_INFO
5371 " task PC stack pid father\n");
5372#else
5373 printk(KERN_INFO
5374 " task PC stack pid father\n");
5375#endif
5376 rcu_read_lock();
5377 for_each_process_thread(g, p) {
5378 /*
5379 * reset the NMI-timeout, listing all files on a slow
5380 * console might take a lot of time:
5381 * Also, reset softlockup watchdogs on all CPUs, because
5382 * another CPU might be blocked waiting for us to process
5383 * an IPI.
5384 */
5385 touch_nmi_watchdog();
5386 touch_all_softlockup_watchdogs();
5387 if (state_filter_match(state_filter, p))
5388 sched_show_task(p);
5389 }
5390
5391#ifdef CONFIG_SCHED_DEBUG
5392 if (!state_filter)
5393 sysrq_sched_debug_show();
5394#endif
5395 rcu_read_unlock();
5396 /*
5397 * Only show locks if all tasks are dumped:
5398 */
5399 if (!state_filter)
5400 debug_show_all_locks();
5401}
5402
5403/**
5404 * init_idle - set up an idle thread for a given CPU
5405 * @idle: task in question
5406 * @cpu: CPU the idle task belongs to
5407 *
5408 * NOTE: this function does not set the idle thread's NEED_RESCHED
5409 * flag, to make booting more robust.
5410 */
5411void init_idle(struct task_struct *idle, int cpu)
5412{
5413 struct rq *rq = cpu_rq(cpu);
5414 unsigned long flags;
5415
5416 raw_spin_lock_irqsave(&idle->pi_lock, flags);
5417 raw_spin_lock(&rq->lock);
5418
5419 __sched_fork(0, idle);
5420 idle->state = TASK_RUNNING;
5421 idle->se.exec_start = sched_clock();
5422 idle->flags |= PF_IDLE;
5423
5424 kasan_unpoison_task_stack(idle);
5425
5426#ifdef CONFIG_SMP
5427 /*
5428 * Its possible that init_idle() gets called multiple times on a task,
5429 * in that case do_set_cpus_allowed() will not do the right thing.
5430 *
5431 * And since this is boot we can forgo the serialization.
5432 */
5433 set_cpus_allowed_common(idle, cpumask_of(cpu));
5434#endif
5435 /*
5436 * We're having a chicken and egg problem, even though we are
5437 * holding rq->lock, the CPU isn't yet set to this CPU so the
5438 * lockdep check in task_group() will fail.
5439 *
5440 * Similar case to sched_fork(). / Alternatively we could
5441 * use task_rq_lock() here and obtain the other rq->lock.
5442 *
5443 * Silence PROVE_RCU
5444 */
5445 rcu_read_lock();
5446 __set_task_cpu(idle, cpu);
5447 rcu_read_unlock();
5448
5449 rq->curr = rq->idle = idle;
5450 idle->on_rq = TASK_ON_RQ_QUEUED;
5451#ifdef CONFIG_SMP
5452 idle->on_cpu = 1;
5453#endif
5454 raw_spin_unlock(&rq->lock);
5455 raw_spin_unlock_irqrestore(&idle->pi_lock, flags);
5456
5457 /* Set the preempt count _outside_ the spinlocks! */
5458 init_idle_preempt_count(idle, cpu);
5459
5460 /*
5461 * The idle tasks have their own, simple scheduling class:
5462 */
5463 idle->sched_class = &idle_sched_class;
5464 ftrace_graph_init_idle_task(idle, cpu);
5465 vtime_init_idle(idle, cpu);
5466#ifdef CONFIG_SMP
5467 sprintf(idle->comm, "%s/%d", INIT_TASK_COMM, cpu);
5468#endif
5469}
5470
5471#ifdef CONFIG_SMP
5472
5473int cpuset_cpumask_can_shrink(const struct cpumask *cur,
5474 const struct cpumask *trial)
5475{
5476 int ret = 1;
5477
5478 if (!cpumask_weight(cur))
5479 return ret;
5480
5481 ret = dl_cpuset_cpumask_can_shrink(cur, trial);
5482
5483 return ret;
5484}
5485
5486int task_can_attach(struct task_struct *p,
5487 const struct cpumask *cs_cpus_allowed)
5488{
5489 int ret = 0;
5490
5491 /*
5492 * Kthreads which disallow setaffinity shouldn't be moved
5493 * to a new cpuset; we don't want to change their CPU
5494 * affinity and isolating such threads by their set of
5495 * allowed nodes is unnecessary. Thus, cpusets are not
5496 * applicable for such threads. This prevents checking for
5497 * success of set_cpus_allowed_ptr() on all attached tasks
5498 * before cpus_allowed may be changed.
5499 */
5500 if (p->flags & PF_NO_SETAFFINITY) {
5501 ret = -EINVAL;
5502 goto out;
5503 }
5504
5505 if (dl_task(p) && !cpumask_intersects(task_rq(p)->rd->span,
5506 cs_cpus_allowed))
5507 ret = dl_task_can_attach(p, cs_cpus_allowed);
5508
5509out:
5510 return ret;
5511}
5512
5513bool sched_smp_initialized __read_mostly;
5514
5515#ifdef CONFIG_NUMA_BALANCING
5516/* Migrate current task p to target_cpu */
5517int migrate_task_to(struct task_struct *p, int target_cpu)
5518{
5519 struct migration_arg arg = { p, target_cpu };
5520 int curr_cpu = task_cpu(p);
5521
5522 if (curr_cpu == target_cpu)
5523 return 0;
5524
5525 if (!cpumask_test_cpu(target_cpu, &p->cpus_allowed))
5526 return -EINVAL;
5527
5528 /* TODO: This is not properly updating schedstats */
5529
5530 trace_sched_move_numa(p, curr_cpu, target_cpu);
5531 return stop_one_cpu(curr_cpu, migration_cpu_stop, &arg);
5532}
5533
5534/*
5535 * Requeue a task on a given node and accurately track the number of NUMA
5536 * tasks on the runqueues
5537 */
5538void sched_setnuma(struct task_struct *p, int nid)
5539{
5540 bool queued, running;
5541 struct rq_flags rf;
5542 struct rq *rq;
5543
5544 rq = task_rq_lock(p, &rf);
5545 queued = task_on_rq_queued(p);
5546 running = task_current(rq, p);
5547
5548 if (queued)
5549 dequeue_task(rq, p, DEQUEUE_SAVE);
5550 if (running)
5551 put_prev_task(rq, p);
5552
5553 p->numa_preferred_nid = nid;
5554
5555 if (queued)
5556 enqueue_task(rq, p, ENQUEUE_RESTORE | ENQUEUE_NOCLOCK);
5557 if (running)
5558 set_curr_task(rq, p);
5559 task_rq_unlock(rq, p, &rf);
5560}
5561#endif /* CONFIG_NUMA_BALANCING */
5562
5563#ifdef CONFIG_HOTPLUG_CPU
5564/*
5565 * Ensure that the idle task is using init_mm right before its CPU goes
5566 * offline.
5567 */
5568void idle_task_exit(void)
5569{
5570 struct mm_struct *mm = current->active_mm;
5571
5572 BUG_ON(cpu_online(smp_processor_id()));
5573
5574 if (mm != &init_mm) {
5575 switch_mm(mm, &init_mm, current);
5576 current->active_mm = &init_mm;
5577 finish_arch_post_lock_switch();
5578 }
5579 mmdrop(mm);
5580}
5581
5582/*
5583 * Since this CPU is going 'away' for a while, fold any nr_active delta
5584 * we might have. Assumes we're called after migrate_tasks() so that the
5585 * nr_active count is stable. We need to take the teardown thread which
5586 * is calling this into account, so we hand in adjust = 1 to the load
5587 * calculation.
5588 *
5589 * Also see the comment "Global load-average calculations".
5590 */
5591static void calc_load_migrate(struct rq *rq)
5592{
5593 long delta = calc_load_fold_active(rq, 1);
5594 if (delta)
5595 atomic_long_add(delta, &calc_load_tasks);
5596}
5597
5598static void put_prev_task_fake(struct rq *rq, struct task_struct *prev)
5599{
5600}
5601
5602static const struct sched_class fake_sched_class = {
5603 .put_prev_task = put_prev_task_fake,
5604};
5605
5606static struct task_struct fake_task = {
5607 /*
5608 * Avoid pull_{rt,dl}_task()
5609 */
5610 .prio = MAX_PRIO + 1,
5611 .sched_class = &fake_sched_class,
5612};
5613
5614/*
5615 * Migrate all tasks from the rq, sleeping tasks will be migrated by
5616 * try_to_wake_up()->select_task_rq().
5617 *
5618 * Called with rq->lock held even though we'er in stop_machine() and
5619 * there's no concurrency possible, we hold the required locks anyway
5620 * because of lock validation efforts.
5621 */
5622static void migrate_tasks(struct rq *dead_rq, struct rq_flags *rf)
5623{
5624 struct rq *rq = dead_rq;
5625 struct task_struct *next, *stop = rq->stop;
5626 struct rq_flags orf = *rf;
5627 int dest_cpu;
5628
5629 /*
5630 * Fudge the rq selection such that the below task selection loop
5631 * doesn't get stuck on the currently eligible stop task.
5632 *
5633 * We're currently inside stop_machine() and the rq is either stuck
5634 * in the stop_machine_cpu_stop() loop, or we're executing this code,
5635 * either way we should never end up calling schedule() until we're
5636 * done here.
5637 */
5638 rq->stop = NULL;
5639
5640 /*
5641 * put_prev_task() and pick_next_task() sched
5642 * class method both need to have an up-to-date
5643 * value of rq->clock[_task]
5644 */
5645 update_rq_clock(rq);
5646
5647 for (;;) {
5648 /*
5649 * There's this thread running, bail when that's the only
5650 * remaining thread:
5651 */
5652 if (rq->nr_running == 1)
5653 break;
5654
5655 /*
5656 * pick_next_task() assumes pinned rq->lock:
5657 */
5658 next = pick_next_task(rq, &fake_task, rf);
5659 BUG_ON(!next);
5660 put_prev_task(rq, next);
5661
5662 /*
5663 * Rules for changing task_struct::cpus_allowed are holding
5664 * both pi_lock and rq->lock, such that holding either
5665 * stabilizes the mask.
5666 *
5667 * Drop rq->lock is not quite as disastrous as it usually is
5668 * because !cpu_active at this point, which means load-balance
5669 * will not interfere. Also, stop-machine.
5670 */
5671 rq_unlock(rq, rf);
5672 raw_spin_lock(&next->pi_lock);
5673 rq_relock(rq, rf);
5674
5675 /*
5676 * Since we're inside stop-machine, _nothing_ should have
5677 * changed the task, WARN if weird stuff happened, because in
5678 * that case the above rq->lock drop is a fail too.
5679 */
5680 if (WARN_ON(task_rq(next) != rq || !task_on_rq_queued(next))) {
5681 raw_spin_unlock(&next->pi_lock);
5682 continue;
5683 }
5684
5685 /* Find suitable destination for @next, with force if needed. */
5686 dest_cpu = select_fallback_rq(dead_rq->cpu, next);
5687 rq = __migrate_task(rq, rf, next, dest_cpu);
5688 if (rq != dead_rq) {
5689 rq_unlock(rq, rf);
5690 rq = dead_rq;
5691 *rf = orf;
5692 rq_relock(rq, rf);
5693 }
5694 raw_spin_unlock(&next->pi_lock);
5695 }
5696
5697 rq->stop = stop;
5698}
5699#endif /* CONFIG_HOTPLUG_CPU */
5700
5701void set_rq_online(struct rq *rq)
5702{
5703 if (!rq->online) {
5704 const struct sched_class *class;
5705
5706 cpumask_set_cpu(rq->cpu, rq->rd->online);
5707 rq->online = 1;
5708
5709 for_each_class(class) {
5710 if (class->rq_online)
5711 class->rq_online(rq);
5712 }
5713 }
5714}
5715
5716void set_rq_offline(struct rq *rq)
5717{
5718 if (rq->online) {
5719 const struct sched_class *class;
5720
5721 for_each_class(class) {
5722 if (class->rq_offline)
5723 class->rq_offline(rq);
5724 }
5725
5726 cpumask_clear_cpu(rq->cpu, rq->rd->online);
5727 rq->online = 0;
5728 }
5729}
5730
5731static void set_cpu_rq_start_time(unsigned int cpu)
5732{
5733 struct rq *rq = cpu_rq(cpu);
5734
5735 rq->age_stamp = sched_clock_cpu(cpu);
5736}
5737
5738/*
5739 * used to mark begin/end of suspend/resume:
5740 */
5741static int num_cpus_frozen;
5742
5743/*
5744 * Update cpusets according to cpu_active mask. If cpusets are
5745 * disabled, cpuset_update_active_cpus() becomes a simple wrapper
5746 * around partition_sched_domains().
5747 *
5748 * If we come here as part of a suspend/resume, don't touch cpusets because we
5749 * want to restore it back to its original state upon resume anyway.
5750 */
5751static void cpuset_cpu_active(void)
5752{
5753 if (cpuhp_tasks_frozen) {
5754 /*
5755 * num_cpus_frozen tracks how many CPUs are involved in suspend
5756 * resume sequence. As long as this is not the last online
5757 * operation in the resume sequence, just build a single sched
5758 * domain, ignoring cpusets.
5759 */
5760 partition_sched_domains(1, NULL, NULL);
5761 if (--num_cpus_frozen)
5762 return;
5763 /*
5764 * This is the last CPU online operation. So fall through and
5765 * restore the original sched domains by considering the
5766 * cpuset configurations.
5767 */
5768 cpuset_force_rebuild();
5769 }
5770 cpuset_update_active_cpus();
5771}
5772
5773static int cpuset_cpu_inactive(unsigned int cpu)
5774{
5775 if (!cpuhp_tasks_frozen) {
5776 if (dl_cpu_busy(cpu))
5777 return -EBUSY;
5778 cpuset_update_active_cpus();
5779 } else {
5780 num_cpus_frozen++;
5781 partition_sched_domains(1, NULL, NULL);
5782 }
5783 return 0;
5784}
5785
5786int sched_cpu_activate(unsigned int cpu)
5787{
5788 struct rq *rq = cpu_rq(cpu);
5789 struct rq_flags rf;
5790
5791 set_cpu_active(cpu, true);
5792
5793 if (sched_smp_initialized) {
5794 sched_domains_numa_masks_set(cpu);
5795 cpuset_cpu_active();
5796 }
5797
5798 /*
5799 * Put the rq online, if not already. This happens:
5800 *
5801 * 1) In the early boot process, because we build the real domains
5802 * after all CPUs have been brought up.
5803 *
5804 * 2) At runtime, if cpuset_cpu_active() fails to rebuild the
5805 * domains.
5806 */
5807 rq_lock_irqsave(rq, &rf);
5808 if (rq->rd) {
5809 BUG_ON(!cpumask_test_cpu(cpu, rq->rd->span));
5810 set_rq_online(rq);
5811 }
5812 rq_unlock_irqrestore(rq, &rf);
5813
5814 update_max_interval();
5815
5816 return 0;
5817}
5818
5819int sched_cpu_deactivate(unsigned int cpu)
5820{
5821 int ret;
5822
5823 set_cpu_active(cpu, false);
5824 /*
5825 * We've cleared cpu_active_mask, wait for all preempt-disabled and RCU
5826 * users of this state to go away such that all new such users will
5827 * observe it.
5828 *
5829 * Do sync before park smpboot threads to take care the rcu boost case.
5830 */
5831 synchronize_rcu_mult(call_rcu, call_rcu_sched);
5832
5833 if (!sched_smp_initialized)
5834 return 0;
5835
5836 ret = cpuset_cpu_inactive(cpu);
5837 if (ret) {
5838 set_cpu_active(cpu, true);
5839 return ret;
5840 }
5841 sched_domains_numa_masks_clear(cpu);
5842 return 0;
5843}
5844
5845static void sched_rq_cpu_starting(unsigned int cpu)
5846{
5847 struct rq *rq = cpu_rq(cpu);
5848
5849 rq->calc_load_update = calc_load_update;
5850 update_max_interval();
5851}
5852
5853int sched_cpu_starting(unsigned int cpu)
5854{
5855 set_cpu_rq_start_time(cpu);
5856 sched_rq_cpu_starting(cpu);
5857 sched_tick_start(cpu);
5858 return 0;
5859}
5860
5861#ifdef CONFIG_HOTPLUG_CPU
5862int sched_cpu_dying(unsigned int cpu)
5863{
5864 struct rq *rq = cpu_rq(cpu);
5865 struct rq_flags rf;
5866
5867 /* Handle pending wakeups and then migrate everything off */
5868 sched_ttwu_pending();
5869 sched_tick_stop(cpu);
5870
5871 rq_lock_irqsave(rq, &rf);
5872 if (rq->rd) {
5873 BUG_ON(!cpumask_test_cpu(cpu, rq->rd->span));
5874 set_rq_offline(rq);
5875 }
5876 migrate_tasks(rq, &rf);
5877 BUG_ON(rq->nr_running != 1);
5878 rq_unlock_irqrestore(rq, &rf);
5879
5880 calc_load_migrate(rq);
5881 update_max_interval();
5882 nohz_balance_exit_idle(rq);
5883 hrtick_clear(rq);
5884 return 0;
5885}
5886#endif
5887
5888#ifdef CONFIG_SCHED_SMT
5889DEFINE_STATIC_KEY_FALSE(sched_smt_present);
5890
5891static void sched_init_smt(void)
5892{
5893 /*
5894 * We've enumerated all CPUs and will assume that if any CPU
5895 * has SMT siblings, CPU0 will too.
5896 */
5897 if (cpumask_weight(cpu_smt_mask(0)) > 1)
5898 static_branch_enable(&sched_smt_present);
5899}
5900#else
5901static inline void sched_init_smt(void) { }
5902#endif
5903
5904void __init sched_init_smp(void)
5905{
5906 sched_init_numa();
5907
5908 /*
5909 * There's no userspace yet to cause hotplug operations; hence all the
5910 * CPU masks are stable and all blatant races in the below code cannot
5911 * happen.
5912 */
5913 mutex_lock(&sched_domains_mutex);
5914 sched_init_domains(cpu_active_mask);
5915 mutex_unlock(&sched_domains_mutex);
5916
5917 /* Move init over to a non-isolated CPU */
5918 if (set_cpus_allowed_ptr(current, housekeeping_cpumask(HK_FLAG_DOMAIN)) < 0)
5919 BUG();
5920 sched_init_granularity();
5921
5922 init_sched_rt_class();
5923 init_sched_dl_class();
5924
5925 sched_init_smt();
5926
5927 sched_smp_initialized = true;
5928}
5929
5930static int __init migration_init(void)
5931{
5932 sched_rq_cpu_starting(smp_processor_id());
5933 return 0;
5934}
5935early_initcall(migration_init);
5936
5937#else
5938void __init sched_init_smp(void)
5939{
5940 sched_init_granularity();
5941}
5942#endif /* CONFIG_SMP */
5943
5944int in_sched_functions(unsigned long addr)
5945{
5946 return in_lock_functions(addr) ||
5947 (addr >= (unsigned long)__sched_text_start
5948 && addr < (unsigned long)__sched_text_end);
5949}
5950
5951#ifdef CONFIG_CGROUP_SCHED
5952/*
5953 * Default task group.
5954 * Every task in system belongs to this group at bootup.
5955 */
5956struct task_group root_task_group;
5957LIST_HEAD(task_groups);
5958
5959/* Cacheline aligned slab cache for task_group */
5960static struct kmem_cache *task_group_cache __read_mostly;
5961#endif
5962
5963DECLARE_PER_CPU(cpumask_var_t, load_balance_mask);
5964DECLARE_PER_CPU(cpumask_var_t, select_idle_mask);
5965
5966void __init sched_init(void)
5967{
5968 int i, j;
5969 unsigned long alloc_size = 0, ptr;
5970
5971 sched_clock_init();
5972 wait_bit_init();
5973
5974#ifdef CONFIG_FAIR_GROUP_SCHED
5975 alloc_size += 2 * nr_cpu_ids * sizeof(void **);
5976#endif
5977#ifdef CONFIG_RT_GROUP_SCHED
5978 alloc_size += 2 * nr_cpu_ids * sizeof(void **);
5979#endif
5980 if (alloc_size) {
5981 ptr = (unsigned long)kzalloc(alloc_size, GFP_NOWAIT);
5982
5983#ifdef CONFIG_FAIR_GROUP_SCHED
5984 root_task_group.se = (struct sched_entity **)ptr;
5985 ptr += nr_cpu_ids * sizeof(void **);
5986
5987 root_task_group.cfs_rq = (struct cfs_rq **)ptr;
5988 ptr += nr_cpu_ids * sizeof(void **);
5989
5990#endif /* CONFIG_FAIR_GROUP_SCHED */
5991#ifdef CONFIG_RT_GROUP_SCHED
5992 root_task_group.rt_se = (struct sched_rt_entity **)ptr;
5993 ptr += nr_cpu_ids * sizeof(void **);
5994
5995 root_task_group.rt_rq = (struct rt_rq **)ptr;
5996 ptr += nr_cpu_ids * sizeof(void **);
5997
5998#endif /* CONFIG_RT_GROUP_SCHED */
5999 }
6000#ifdef CONFIG_CPUMASK_OFFSTACK
6001 for_each_possible_cpu(i) {
6002 per_cpu(load_balance_mask, i) = (cpumask_var_t)kzalloc_node(
6003 cpumask_size(), GFP_KERNEL, cpu_to_node(i));
6004 per_cpu(select_idle_mask, i) = (cpumask_var_t)kzalloc_node(
6005 cpumask_size(), GFP_KERNEL, cpu_to_node(i));
6006 }
6007#endif /* CONFIG_CPUMASK_OFFSTACK */
6008
6009 init_rt_bandwidth(&def_rt_bandwidth, global_rt_period(), global_rt_runtime());
6010 init_dl_bandwidth(&def_dl_bandwidth, global_rt_period(), global_rt_runtime());
6011
6012#ifdef CONFIG_SMP
6013 init_defrootdomain();
6014#endif
6015
6016#ifdef CONFIG_RT_GROUP_SCHED
6017 init_rt_bandwidth(&root_task_group.rt_bandwidth,
6018 global_rt_period(), global_rt_runtime());
6019#endif /* CONFIG_RT_GROUP_SCHED */
6020
6021#ifdef CONFIG_CGROUP_SCHED
6022 task_group_cache = KMEM_CACHE(task_group, 0);
6023
6024 list_add(&root_task_group.list, &task_groups);
6025 INIT_LIST_HEAD(&root_task_group.children);
6026 INIT_LIST_HEAD(&root_task_group.siblings);
6027 autogroup_init(&init_task);
6028#endif /* CONFIG_CGROUP_SCHED */
6029
6030 for_each_possible_cpu(i) {
6031 struct rq *rq;
6032
6033 rq = cpu_rq(i);
6034 raw_spin_lock_init(&rq->lock);
6035 rq->nr_running = 0;
6036 rq->calc_load_active = 0;
6037 rq->calc_load_update = jiffies + LOAD_FREQ;
6038 init_cfs_rq(&rq->cfs);
6039 init_rt_rq(&rq->rt);
6040 init_dl_rq(&rq->dl);
6041#ifdef CONFIG_FAIR_GROUP_SCHED
6042 root_task_group.shares = ROOT_TASK_GROUP_LOAD;
6043 INIT_LIST_HEAD(&rq->leaf_cfs_rq_list);
6044 rq->tmp_alone_branch = &rq->leaf_cfs_rq_list;
6045 /*
6046 * How much CPU bandwidth does root_task_group get?
6047 *
6048 * In case of task-groups formed thr' the cgroup filesystem, it
6049 * gets 100% of the CPU resources in the system. This overall
6050 * system CPU resource is divided among the tasks of
6051 * root_task_group and its child task-groups in a fair manner,
6052 * based on each entity's (task or task-group's) weight
6053 * (se->load.weight).
6054 *
6055 * In other words, if root_task_group has 10 tasks of weight
6056 * 1024) and two child groups A0 and A1 (of weight 1024 each),
6057 * then A0's share of the CPU resource is:
6058 *
6059 * A0's bandwidth = 1024 / (10*1024 + 1024 + 1024) = 8.33%
6060 *
6061 * We achieve this by letting root_task_group's tasks sit
6062 * directly in rq->cfs (i.e root_task_group->se[] = NULL).
6063 */
6064 init_cfs_bandwidth(&root_task_group.cfs_bandwidth);
6065 init_tg_cfs_entry(&root_task_group, &rq->cfs, NULL, i, NULL);
6066#endif /* CONFIG_FAIR_GROUP_SCHED */
6067
6068 rq->rt.rt_runtime = def_rt_bandwidth.rt_runtime;
6069#ifdef CONFIG_RT_GROUP_SCHED
6070 init_tg_rt_entry(&root_task_group, &rq->rt, NULL, i, NULL);
6071#endif
6072
6073 for (j = 0; j < CPU_LOAD_IDX_MAX; j++)
6074 rq->cpu_load[j] = 0;
6075
6076#ifdef CONFIG_SMP
6077 rq->sd = NULL;
6078 rq->rd = NULL;
6079 rq->cpu_capacity = rq->cpu_capacity_orig = SCHED_CAPACITY_SCALE;
6080 rq->balance_callback = NULL;
6081 rq->active_balance = 0;
6082 rq->next_balance = jiffies;
6083 rq->push_cpu = 0;
6084 rq->cpu = i;
6085 rq->online = 0;
6086 rq->idle_stamp = 0;
6087 rq->avg_idle = 2*sysctl_sched_migration_cost;
6088 rq->max_idle_balance_cost = sysctl_sched_migration_cost;
6089
6090 INIT_LIST_HEAD(&rq->cfs_tasks);
6091
6092 rq_attach_root(rq, &def_root_domain);
6093#ifdef CONFIG_NO_HZ_COMMON
6094 rq->last_load_update_tick = jiffies;
6095 rq->last_blocked_load_update_tick = jiffies;
6096 atomic_set(&rq->nohz_flags, 0);
6097#endif
6098#endif /* CONFIG_SMP */
6099 hrtick_rq_init(rq);
6100 atomic_set(&rq->nr_iowait, 0);
6101 }
6102
6103 set_load_weight(&init_task, false);
6104
6105 /*
6106 * The boot idle thread does lazy MMU switching as well:
6107 */
6108 mmgrab(&init_mm);
6109 enter_lazy_tlb(&init_mm, current);
6110
6111 /*
6112 * Make us the idle thread. Technically, schedule() should not be
6113 * called from this thread, however somewhere below it might be,
6114 * but because we are the idle thread, we just pick up running again
6115 * when this runqueue becomes "idle".
6116 */
6117 init_idle(current, smp_processor_id());
6118
6119 calc_load_update = jiffies + LOAD_FREQ;
6120
6121#ifdef CONFIG_SMP
6122 idle_thread_set_boot_cpu();
6123 set_cpu_rq_start_time(smp_processor_id());
6124#endif
6125 init_sched_fair_class();
6126
6127 init_schedstats();
6128
6129 scheduler_running = 1;
6130}
6131
6132#ifdef CONFIG_DEBUG_ATOMIC_SLEEP
6133static inline int preempt_count_equals(int preempt_offset)
6134{
6135 int nested = preempt_count() + rcu_preempt_depth();
6136
6137 return (nested == preempt_offset);
6138}
6139
6140void __might_sleep(const char *file, int line, int preempt_offset)
6141{
6142 /*
6143 * Blocking primitives will set (and therefore destroy) current->state,
6144 * since we will exit with TASK_RUNNING make sure we enter with it,
6145 * otherwise we will destroy state.
6146 */
6147 WARN_ONCE(current->state != TASK_RUNNING && current->task_state_change,
6148 "do not call blocking ops when !TASK_RUNNING; "
6149 "state=%lx set at [<%p>] %pS\n",
6150 current->state,
6151 (void *)current->task_state_change,
6152 (void *)current->task_state_change);
6153
6154 ___might_sleep(file, line, preempt_offset);
6155}
6156EXPORT_SYMBOL(__might_sleep);
6157
6158void ___might_sleep(const char *file, int line, int preempt_offset)
6159{
6160 /* Ratelimiting timestamp: */
6161 static unsigned long prev_jiffy;
6162
6163 unsigned long preempt_disable_ip;
6164
6165 /* WARN_ON_ONCE() by default, no rate limit required: */
6166 rcu_sleep_check();
6167
6168 if ((preempt_count_equals(preempt_offset) && !irqs_disabled() &&
6169 !is_idle_task(current)) ||
6170 system_state == SYSTEM_BOOTING || system_state > SYSTEM_RUNNING ||
6171 oops_in_progress)
6172 return;
6173
6174 if (time_before(jiffies, prev_jiffy + HZ) && prev_jiffy)
6175 return;
6176 prev_jiffy = jiffies;
6177
6178 /* Save this before calling printk(), since that will clobber it: */
6179 preempt_disable_ip = get_preempt_disable_ip(current);
6180
6181 printk(KERN_ERR
6182 "BUG: sleeping function called from invalid context at %s:%d\n",
6183 file, line);
6184 printk(KERN_ERR
6185 "in_atomic(): %d, irqs_disabled(): %d, pid: %d, name: %s\n",
6186 in_atomic(), irqs_disabled(),
6187 current->pid, current->comm);
6188
6189 if (task_stack_end_corrupted(current))
6190 printk(KERN_EMERG "Thread overran stack, or stack corrupted\n");
6191
6192 debug_show_held_locks(current);
6193 if (irqs_disabled())
6194 print_irqtrace_events(current);
6195 if (IS_ENABLED(CONFIG_DEBUG_PREEMPT)
6196 && !preempt_count_equals(preempt_offset)) {
6197 pr_err("Preemption disabled at:");
6198 print_ip_sym(preempt_disable_ip);
6199 pr_cont("\n");
6200 }
6201 dump_stack();
6202 add_taint(TAINT_WARN, LOCKDEP_STILL_OK);
6203}
6204EXPORT_SYMBOL(___might_sleep);
6205#endif
6206
6207#ifdef CONFIG_MAGIC_SYSRQ
6208void normalize_rt_tasks(void)
6209{
6210 struct task_struct *g, *p;
6211 struct sched_attr attr = {
6212 .sched_policy = SCHED_NORMAL,
6213 };
6214
6215 read_lock(&tasklist_lock);
6216 for_each_process_thread(g, p) {
6217 /*
6218 * Only normalize user tasks:
6219 */
6220 if (p->flags & PF_KTHREAD)
6221 continue;
6222
6223 p->se.exec_start = 0;
6224 schedstat_set(p->se.statistics.wait_start, 0);
6225 schedstat_set(p->se.statistics.sleep_start, 0);
6226 schedstat_set(p->se.statistics.block_start, 0);
6227
6228 if (!dl_task(p) && !rt_task(p)) {
6229 /*
6230 * Renice negative nice level userspace
6231 * tasks back to 0:
6232 */
6233 if (task_nice(p) < 0)
6234 set_user_nice(p, 0);
6235 continue;
6236 }
6237
6238 __sched_setscheduler(p, &attr, false, false);
6239 }
6240 read_unlock(&tasklist_lock);
6241}
6242
6243#endif /* CONFIG_MAGIC_SYSRQ */
6244
6245#if defined(CONFIG_IA64) || defined(CONFIG_KGDB_KDB)
6246/*
6247 * These functions are only useful for the IA64 MCA handling, or kdb.
6248 *
6249 * They can only be called when the whole system has been
6250 * stopped - every CPU needs to be quiescent, and no scheduling
6251 * activity can take place. Using them for anything else would
6252 * be a serious bug, and as a result, they aren't even visible
6253 * under any other configuration.
6254 */
6255
6256/**
6257 * curr_task - return the current task for a given CPU.
6258 * @cpu: the processor in question.
6259 *
6260 * ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED!
6261 *
6262 * Return: The current task for @cpu.
6263 */
6264struct task_struct *curr_task(int cpu)
6265{
6266 return cpu_curr(cpu);
6267}
6268
6269#endif /* defined(CONFIG_IA64) || defined(CONFIG_KGDB_KDB) */
6270
6271#ifdef CONFIG_IA64
6272/**
6273 * set_curr_task - set the current task for a given CPU.
6274 * @cpu: the processor in question.
6275 * @p: the task pointer to set.
6276 *
6277 * Description: This function must only be used when non-maskable interrupts
6278 * are serviced on a separate stack. It allows the architecture to switch the
6279 * notion of the current task on a CPU in a non-blocking manner. This function
6280 * must be called with all CPU's synchronized, and interrupts disabled, the
6281 * and caller must save the original value of the current task (see
6282 * curr_task() above) and restore that value before reenabling interrupts and
6283 * re-starting the system.
6284 *
6285 * ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED!
6286 */
6287void ia64_set_curr_task(int cpu, struct task_struct *p)
6288{
6289 cpu_curr(cpu) = p;
6290}
6291
6292#endif
6293
6294#ifdef CONFIG_CGROUP_SCHED
6295/* task_group_lock serializes the addition/removal of task groups */
6296static DEFINE_SPINLOCK(task_group_lock);
6297
6298static void sched_free_group(struct task_group *tg)
6299{
6300 free_fair_sched_group(tg);
6301 free_rt_sched_group(tg);
6302 autogroup_free(tg);
6303 kmem_cache_free(task_group_cache, tg);
6304}
6305
6306/* allocate runqueue etc for a new task group */
6307struct task_group *sched_create_group(struct task_group *parent)
6308{
6309 struct task_group *tg;
6310
6311 tg = kmem_cache_alloc(task_group_cache, GFP_KERNEL | __GFP_ZERO);
6312 if (!tg)
6313 return ERR_PTR(-ENOMEM);
6314
6315 if (!alloc_fair_sched_group(tg, parent))
6316 goto err;
6317
6318 if (!alloc_rt_sched_group(tg, parent))
6319 goto err;
6320
6321 return tg;
6322
6323err:
6324 sched_free_group(tg);
6325 return ERR_PTR(-ENOMEM);
6326}
6327
6328void sched_online_group(struct task_group *tg, struct task_group *parent)
6329{
6330 unsigned long flags;
6331
6332 spin_lock_irqsave(&task_group_lock, flags);
6333 list_add_rcu(&tg->list, &task_groups);
6334
6335 /* Root should already exist: */
6336 WARN_ON(!parent);
6337
6338 tg->parent = parent;
6339 INIT_LIST_HEAD(&tg->children);
6340 list_add_rcu(&tg->siblings, &parent->children);
6341 spin_unlock_irqrestore(&task_group_lock, flags);
6342
6343 online_fair_sched_group(tg);
6344}
6345
6346/* rcu callback to free various structures associated with a task group */
6347static void sched_free_group_rcu(struct rcu_head *rhp)
6348{
6349 /* Now it should be safe to free those cfs_rqs: */
6350 sched_free_group(container_of(rhp, struct task_group, rcu));
6351}
6352
6353void sched_destroy_group(struct task_group *tg)
6354{
6355 /* Wait for possible concurrent references to cfs_rqs complete: */
6356 call_rcu(&tg->rcu, sched_free_group_rcu);
6357}
6358
6359void sched_offline_group(struct task_group *tg)
6360{
6361 unsigned long flags;
6362
6363 /* End participation in shares distribution: */
6364 unregister_fair_sched_group(tg);
6365
6366 spin_lock_irqsave(&task_group_lock, flags);
6367 list_del_rcu(&tg->list);
6368 list_del_rcu(&tg->siblings);
6369 spin_unlock_irqrestore(&task_group_lock, flags);
6370}
6371
6372static void sched_change_group(struct task_struct *tsk, int type)
6373{
6374 struct task_group *tg;
6375
6376 /*
6377 * All callers are synchronized by task_rq_lock(); we do not use RCU
6378 * which is pointless here. Thus, we pass "true" to task_css_check()
6379 * to prevent lockdep warnings.
6380 */
6381 tg = container_of(task_css_check(tsk, cpu_cgrp_id, true),
6382 struct task_group, css);
6383 tg = autogroup_task_group(tsk, tg);
6384 tsk->sched_task_group = tg;
6385
6386#ifdef CONFIG_FAIR_GROUP_SCHED
6387 if (tsk->sched_class->task_change_group)
6388 tsk->sched_class->task_change_group(tsk, type);
6389 else
6390#endif
6391 set_task_rq(tsk, task_cpu(tsk));
6392}
6393
6394/*
6395 * Change task's runqueue when it moves between groups.
6396 *
6397 * The caller of this function should have put the task in its new group by
6398 * now. This function just updates tsk->se.cfs_rq and tsk->se.parent to reflect
6399 * its new group.
6400 */
6401void sched_move_task(struct task_struct *tsk)
6402{
6403 int queued, running, queue_flags =
6404 DEQUEUE_SAVE | DEQUEUE_MOVE | DEQUEUE_NOCLOCK;
6405 struct rq_flags rf;
6406 struct rq *rq;
6407
6408 rq = task_rq_lock(tsk, &rf);
6409 update_rq_clock(rq);
6410
6411 running = task_current(rq, tsk);
6412 queued = task_on_rq_queued(tsk);
6413
6414 if (queued)
6415 dequeue_task(rq, tsk, queue_flags);
6416 if (running)
6417 put_prev_task(rq, tsk);
6418
6419 sched_change_group(tsk, TASK_MOVE_GROUP);
6420
6421 if (queued)
6422 enqueue_task(rq, tsk, queue_flags);
6423 if (running)
6424 set_curr_task(rq, tsk);
6425
6426 task_rq_unlock(rq, tsk, &rf);
6427}
6428
6429static inline struct task_group *css_tg(struct cgroup_subsys_state *css)
6430{
6431 return css ? container_of(css, struct task_group, css) : NULL;
6432}
6433
6434static struct cgroup_subsys_state *
6435cpu_cgroup_css_alloc(struct cgroup_subsys_state *parent_css)
6436{
6437 struct task_group *parent = css_tg(parent_css);
6438 struct task_group *tg;
6439
6440 if (!parent) {
6441 /* This is early initialization for the top cgroup */
6442 return &root_task_group.css;
6443 }
6444
6445 tg = sched_create_group(parent);
6446 if (IS_ERR(tg))
6447 return ERR_PTR(-ENOMEM);
6448
6449 return &tg->css;
6450}
6451
6452/* Expose task group only after completing cgroup initialization */
6453static int cpu_cgroup_css_online(struct cgroup_subsys_state *css)
6454{
6455 struct task_group *tg = css_tg(css);
6456 struct task_group *parent = css_tg(css->parent);
6457
6458 if (parent)
6459 sched_online_group(tg, parent);
6460 return 0;
6461}
6462
6463static void cpu_cgroup_css_released(struct cgroup_subsys_state *css)
6464{
6465 struct task_group *tg = css_tg(css);
6466
6467 sched_offline_group(tg);
6468}
6469
6470static void cpu_cgroup_css_free(struct cgroup_subsys_state *css)
6471{
6472 struct task_group *tg = css_tg(css);
6473
6474 /*
6475 * Relies on the RCU grace period between css_released() and this.
6476 */
6477 sched_free_group(tg);
6478}
6479
6480/*
6481 * This is called before wake_up_new_task(), therefore we really only
6482 * have to set its group bits, all the other stuff does not apply.
6483 */
6484static void cpu_cgroup_fork(struct task_struct *task)
6485{
6486 struct rq_flags rf;
6487 struct rq *rq;
6488
6489 rq = task_rq_lock(task, &rf);
6490
6491 update_rq_clock(rq);
6492 sched_change_group(task, TASK_SET_GROUP);
6493
6494 task_rq_unlock(rq, task, &rf);
6495}
6496
6497static int cpu_cgroup_can_attach(struct cgroup_taskset *tset)
6498{
6499 struct task_struct *task;
6500 struct cgroup_subsys_state *css;
6501 int ret = 0;
6502
6503 cgroup_taskset_for_each(task, css, tset) {
6504#ifdef CONFIG_RT_GROUP_SCHED
6505 if (!sched_rt_can_attach(css_tg(css), task))
6506 return -EINVAL;
6507#else
6508 /* We don't support RT-tasks being in separate groups */
6509 if (task->sched_class != &fair_sched_class)
6510 return -EINVAL;
6511#endif
6512 /*
6513 * Serialize against wake_up_new_task() such that if its
6514 * running, we're sure to observe its full state.
6515 */
6516 raw_spin_lock_irq(&task->pi_lock);
6517 /*
6518 * Avoid calling sched_move_task() before wake_up_new_task()
6519 * has happened. This would lead to problems with PELT, due to
6520 * move wanting to detach+attach while we're not attached yet.
6521 */
6522 if (task->state == TASK_NEW)
6523 ret = -EINVAL;
6524 raw_spin_unlock_irq(&task->pi_lock);
6525
6526 if (ret)
6527 break;
6528 }
6529 return ret;
6530}
6531
6532static void cpu_cgroup_attach(struct cgroup_taskset *tset)
6533{
6534 struct task_struct *task;
6535 struct cgroup_subsys_state *css;
6536
6537 cgroup_taskset_for_each(task, css, tset)
6538 sched_move_task(task);
6539}
6540
6541#ifdef CONFIG_FAIR_GROUP_SCHED
6542static int cpu_shares_write_u64(struct cgroup_subsys_state *css,
6543 struct cftype *cftype, u64 shareval)
6544{
6545 return sched_group_set_shares(css_tg(css), scale_load(shareval));
6546}
6547
6548static u64 cpu_shares_read_u64(struct cgroup_subsys_state *css,
6549 struct cftype *cft)
6550{
6551 struct task_group *tg = css_tg(css);
6552
6553 return (u64) scale_load_down(tg->shares);
6554}
6555
6556#ifdef CONFIG_CFS_BANDWIDTH
6557static DEFINE_MUTEX(cfs_constraints_mutex);
6558
6559const u64 max_cfs_quota_period = 1 * NSEC_PER_SEC; /* 1s */
6560const u64 min_cfs_quota_period = 1 * NSEC_PER_MSEC; /* 1ms */
6561
6562static int __cfs_schedulable(struct task_group *tg, u64 period, u64 runtime);
6563
6564static int tg_set_cfs_bandwidth(struct task_group *tg, u64 period, u64 quota)
6565{
6566 int i, ret = 0, runtime_enabled, runtime_was_enabled;
6567 struct cfs_bandwidth *cfs_b = &tg->cfs_bandwidth;
6568
6569 if (tg == &root_task_group)
6570 return -EINVAL;
6571
6572 /*
6573 * Ensure we have at some amount of bandwidth every period. This is
6574 * to prevent reaching a state of large arrears when throttled via
6575 * entity_tick() resulting in prolonged exit starvation.
6576 */
6577 if (quota < min_cfs_quota_period || period < min_cfs_quota_period)
6578 return -EINVAL;
6579
6580 /*
6581 * Likewise, bound things on the otherside by preventing insane quota
6582 * periods. This also allows us to normalize in computing quota
6583 * feasibility.
6584 */
6585 if (period > max_cfs_quota_period)
6586 return -EINVAL;
6587
6588 /*
6589 * Prevent race between setting of cfs_rq->runtime_enabled and
6590 * unthrottle_offline_cfs_rqs().
6591 */
6592 get_online_cpus();
6593 mutex_lock(&cfs_constraints_mutex);
6594 ret = __cfs_schedulable(tg, period, quota);
6595 if (ret)
6596 goto out_unlock;
6597
6598 runtime_enabled = quota != RUNTIME_INF;
6599 runtime_was_enabled = cfs_b->quota != RUNTIME_INF;
6600 /*
6601 * If we need to toggle cfs_bandwidth_used, off->on must occur
6602 * before making related changes, and on->off must occur afterwards
6603 */
6604 if (runtime_enabled && !runtime_was_enabled)
6605 cfs_bandwidth_usage_inc();
6606 raw_spin_lock_irq(&cfs_b->lock);
6607 cfs_b->period = ns_to_ktime(period);
6608 cfs_b->quota = quota;
6609
6610 __refill_cfs_bandwidth_runtime(cfs_b);
6611
6612 /* Restart the period timer (if active) to handle new period expiry: */
6613 if (runtime_enabled)
6614 start_cfs_bandwidth(cfs_b);
6615
6616 raw_spin_unlock_irq(&cfs_b->lock);
6617
6618 for_each_online_cpu(i) {
6619 struct cfs_rq *cfs_rq = tg->cfs_rq[i];
6620 struct rq *rq = cfs_rq->rq;
6621 struct rq_flags rf;
6622
6623 rq_lock_irq(rq, &rf);
6624 cfs_rq->runtime_enabled = runtime_enabled;
6625 cfs_rq->runtime_remaining = 0;
6626
6627 if (cfs_rq->throttled)
6628 unthrottle_cfs_rq(cfs_rq);
6629 rq_unlock_irq(rq, &rf);
6630 }
6631 if (runtime_was_enabled && !runtime_enabled)
6632 cfs_bandwidth_usage_dec();
6633out_unlock:
6634 mutex_unlock(&cfs_constraints_mutex);
6635 put_online_cpus();
6636
6637 return ret;
6638}
6639
6640int tg_set_cfs_quota(struct task_group *tg, long cfs_quota_us)
6641{
6642 u64 quota, period;
6643
6644 period = ktime_to_ns(tg->cfs_bandwidth.period);
6645 if (cfs_quota_us < 0)
6646 quota = RUNTIME_INF;
6647 else
6648 quota = (u64)cfs_quota_us * NSEC_PER_USEC;
6649
6650 return tg_set_cfs_bandwidth(tg, period, quota);
6651}
6652
6653long tg_get_cfs_quota(struct task_group *tg)
6654{
6655 u64 quota_us;
6656
6657 if (tg->cfs_bandwidth.quota == RUNTIME_INF)
6658 return -1;
6659
6660 quota_us = tg->cfs_bandwidth.quota;
6661 do_div(quota_us, NSEC_PER_USEC);
6662
6663 return quota_us;
6664}
6665
6666int tg_set_cfs_period(struct task_group *tg, long cfs_period_us)
6667{
6668 u64 quota, period;
6669
6670 period = (u64)cfs_period_us * NSEC_PER_USEC;
6671 quota = tg->cfs_bandwidth.quota;
6672
6673 return tg_set_cfs_bandwidth(tg, period, quota);
6674}
6675
6676long tg_get_cfs_period(struct task_group *tg)
6677{
6678 u64 cfs_period_us;
6679
6680 cfs_period_us = ktime_to_ns(tg->cfs_bandwidth.period);
6681 do_div(cfs_period_us, NSEC_PER_USEC);
6682
6683 return cfs_period_us;
6684}
6685
6686static s64 cpu_cfs_quota_read_s64(struct cgroup_subsys_state *css,
6687 struct cftype *cft)
6688{
6689 return tg_get_cfs_quota(css_tg(css));
6690}
6691
6692static int cpu_cfs_quota_write_s64(struct cgroup_subsys_state *css,
6693 struct cftype *cftype, s64 cfs_quota_us)
6694{
6695 return tg_set_cfs_quota(css_tg(css), cfs_quota_us);
6696}
6697
6698static u64 cpu_cfs_period_read_u64(struct cgroup_subsys_state *css,
6699 struct cftype *cft)
6700{
6701 return tg_get_cfs_period(css_tg(css));
6702}
6703
6704static int cpu_cfs_period_write_u64(struct cgroup_subsys_state *css,
6705 struct cftype *cftype, u64 cfs_period_us)
6706{
6707 return tg_set_cfs_period(css_tg(css), cfs_period_us);
6708}
6709
6710struct cfs_schedulable_data {
6711 struct task_group *tg;
6712 u64 period, quota;
6713};
6714
6715/*
6716 * normalize group quota/period to be quota/max_period
6717 * note: units are usecs
6718 */
6719static u64 normalize_cfs_quota(struct task_group *tg,
6720 struct cfs_schedulable_data *d)
6721{
6722 u64 quota, period;
6723
6724 if (tg == d->tg) {
6725 period = d->period;
6726 quota = d->quota;
6727 } else {
6728 period = tg_get_cfs_period(tg);
6729 quota = tg_get_cfs_quota(tg);
6730 }
6731
6732 /* note: these should typically be equivalent */
6733 if (quota == RUNTIME_INF || quota == -1)
6734 return RUNTIME_INF;
6735
6736 return to_ratio(period, quota);
6737}
6738
6739static int tg_cfs_schedulable_down(struct task_group *tg, void *data)
6740{
6741 struct cfs_schedulable_data *d = data;
6742 struct cfs_bandwidth *cfs_b = &tg->cfs_bandwidth;
6743 s64 quota = 0, parent_quota = -1;
6744
6745 if (!tg->parent) {
6746 quota = RUNTIME_INF;
6747 } else {
6748 struct cfs_bandwidth *parent_b = &tg->parent->cfs_bandwidth;
6749
6750 quota = normalize_cfs_quota(tg, d);
6751 parent_quota = parent_b->hierarchical_quota;
6752
6753 /*
6754 * Ensure max(child_quota) <= parent_quota. On cgroup2,
6755 * always take the min. On cgroup1, only inherit when no
6756 * limit is set:
6757 */
6758 if (cgroup_subsys_on_dfl(cpu_cgrp_subsys)) {
6759 quota = min(quota, parent_quota);
6760 } else {
6761 if (quota == RUNTIME_INF)
6762 quota = parent_quota;
6763 else if (parent_quota != RUNTIME_INF && quota > parent_quota)
6764 return -EINVAL;
6765 }
6766 }
6767 cfs_b->hierarchical_quota = quota;
6768
6769 return 0;
6770}
6771
6772static int __cfs_schedulable(struct task_group *tg, u64 period, u64 quota)
6773{
6774 int ret;
6775 struct cfs_schedulable_data data = {
6776 .tg = tg,
6777 .period = period,
6778 .quota = quota,
6779 };
6780
6781 if (quota != RUNTIME_INF) {
6782 do_div(data.period, NSEC_PER_USEC);
6783 do_div(data.quota, NSEC_PER_USEC);
6784 }
6785
6786 rcu_read_lock();
6787 ret = walk_tg_tree(tg_cfs_schedulable_down, tg_nop, &data);
6788 rcu_read_unlock();
6789
6790 return ret;
6791}
6792
6793static int cpu_cfs_stat_show(struct seq_file *sf, void *v)
6794{
6795 struct task_group *tg = css_tg(seq_css(sf));
6796 struct cfs_bandwidth *cfs_b = &tg->cfs_bandwidth;
6797
6798 seq_printf(sf, "nr_periods %d\n", cfs_b->nr_periods);
6799 seq_printf(sf, "nr_throttled %d\n", cfs_b->nr_throttled);
6800 seq_printf(sf, "throttled_time %llu\n", cfs_b->throttled_time);
6801
6802 return 0;
6803}
6804#endif /* CONFIG_CFS_BANDWIDTH */
6805#endif /* CONFIG_FAIR_GROUP_SCHED */
6806
6807#ifdef CONFIG_RT_GROUP_SCHED
6808static int cpu_rt_runtime_write(struct cgroup_subsys_state *css,
6809 struct cftype *cft, s64 val)
6810{
6811 return sched_group_set_rt_runtime(css_tg(css), val);
6812}
6813
6814static s64 cpu_rt_runtime_read(struct cgroup_subsys_state *css,
6815 struct cftype *cft)
6816{
6817 return sched_group_rt_runtime(css_tg(css));
6818}
6819
6820static int cpu_rt_period_write_uint(struct cgroup_subsys_state *css,
6821 struct cftype *cftype, u64 rt_period_us)
6822{
6823 return sched_group_set_rt_period(css_tg(css), rt_period_us);
6824}
6825
6826static u64 cpu_rt_period_read_uint(struct cgroup_subsys_state *css,
6827 struct cftype *cft)
6828{
6829 return sched_group_rt_period(css_tg(css));
6830}
6831#endif /* CONFIG_RT_GROUP_SCHED */
6832
6833static struct cftype cpu_legacy_files[] = {
6834#ifdef CONFIG_FAIR_GROUP_SCHED
6835 {
6836 .name = "shares",
6837 .read_u64 = cpu_shares_read_u64,
6838 .write_u64 = cpu_shares_write_u64,
6839 },
6840#endif
6841#ifdef CONFIG_CFS_BANDWIDTH
6842 {
6843 .name = "cfs_quota_us",
6844 .read_s64 = cpu_cfs_quota_read_s64,
6845 .write_s64 = cpu_cfs_quota_write_s64,
6846 },
6847 {
6848 .name = "cfs_period_us",
6849 .read_u64 = cpu_cfs_period_read_u64,
6850 .write_u64 = cpu_cfs_period_write_u64,
6851 },
6852 {
6853 .name = "stat",
6854 .seq_show = cpu_cfs_stat_show,
6855 },
6856#endif
6857#ifdef CONFIG_RT_GROUP_SCHED
6858 {
6859 .name = "rt_runtime_us",
6860 .read_s64 = cpu_rt_runtime_read,
6861 .write_s64 = cpu_rt_runtime_write,
6862 },
6863 {
6864 .name = "rt_period_us",
6865 .read_u64 = cpu_rt_period_read_uint,
6866 .write_u64 = cpu_rt_period_write_uint,
6867 },
6868#endif
6869 { } /* Terminate */
6870};
6871
6872static int cpu_extra_stat_show(struct seq_file *sf,
6873 struct cgroup_subsys_state *css)
6874{
6875#ifdef CONFIG_CFS_BANDWIDTH
6876 {
6877 struct task_group *tg = css_tg(css);
6878 struct cfs_bandwidth *cfs_b = &tg->cfs_bandwidth;
6879 u64 throttled_usec;
6880
6881 throttled_usec = cfs_b->throttled_time;
6882 do_div(throttled_usec, NSEC_PER_USEC);
6883
6884 seq_printf(sf, "nr_periods %d\n"
6885 "nr_throttled %d\n"
6886 "throttled_usec %llu\n",
6887 cfs_b->nr_periods, cfs_b->nr_throttled,
6888 throttled_usec);
6889 }
6890#endif
6891 return 0;
6892}
6893
6894#ifdef CONFIG_FAIR_GROUP_SCHED
6895static u64 cpu_weight_read_u64(struct cgroup_subsys_state *css,
6896 struct cftype *cft)
6897{
6898 struct task_group *tg = css_tg(css);
6899 u64 weight = scale_load_down(tg->shares);
6900
6901 return DIV_ROUND_CLOSEST_ULL(weight * CGROUP_WEIGHT_DFL, 1024);
6902}
6903
6904static int cpu_weight_write_u64(struct cgroup_subsys_state *css,
6905 struct cftype *cft, u64 weight)
6906{
6907 /*
6908 * cgroup weight knobs should use the common MIN, DFL and MAX
6909 * values which are 1, 100 and 10000 respectively. While it loses
6910 * a bit of range on both ends, it maps pretty well onto the shares
6911 * value used by scheduler and the round-trip conversions preserve
6912 * the original value over the entire range.
6913 */
6914 if (weight < CGROUP_WEIGHT_MIN || weight > CGROUP_WEIGHT_MAX)
6915 return -ERANGE;
6916
6917 weight = DIV_ROUND_CLOSEST_ULL(weight * 1024, CGROUP_WEIGHT_DFL);
6918
6919 return sched_group_set_shares(css_tg(css), scale_load(weight));
6920}
6921
6922static s64 cpu_weight_nice_read_s64(struct cgroup_subsys_state *css,
6923 struct cftype *cft)
6924{
6925 unsigned long weight = scale_load_down(css_tg(css)->shares);
6926 int last_delta = INT_MAX;
6927 int prio, delta;
6928
6929 /* find the closest nice value to the current weight */
6930 for (prio = 0; prio < ARRAY_SIZE(sched_prio_to_weight); prio++) {
6931 delta = abs(sched_prio_to_weight[prio] - weight);
6932 if (delta >= last_delta)
6933 break;
6934 last_delta = delta;
6935 }
6936
6937 return PRIO_TO_NICE(prio - 1 + MAX_RT_PRIO);
6938}
6939
6940static int cpu_weight_nice_write_s64(struct cgroup_subsys_state *css,
6941 struct cftype *cft, s64 nice)
6942{
6943 unsigned long weight;
6944 int idx;
6945
6946 if (nice < MIN_NICE || nice > MAX_NICE)
6947 return -ERANGE;
6948
6949 idx = NICE_TO_PRIO(nice) - MAX_RT_PRIO;
6950 idx = array_index_nospec(idx, 40);
6951 weight = sched_prio_to_weight[idx];
6952
6953 return sched_group_set_shares(css_tg(css), scale_load(weight));
6954}
6955#endif
6956
6957static void __maybe_unused cpu_period_quota_print(struct seq_file *sf,
6958 long period, long quota)
6959{
6960 if (quota < 0)
6961 seq_puts(sf, "max");
6962 else
6963 seq_printf(sf, "%ld", quota);
6964
6965 seq_printf(sf, " %ld\n", period);
6966}
6967
6968/* caller should put the current value in *@periodp before calling */
6969static int __maybe_unused cpu_period_quota_parse(char *buf,
6970 u64 *periodp, u64 *quotap)
6971{
6972 char tok[21]; /* U64_MAX */
6973
6974 if (!sscanf(buf, "%s %llu", tok, periodp))
6975 return -EINVAL;
6976
6977 *periodp *= NSEC_PER_USEC;
6978
6979 if (sscanf(tok, "%llu", quotap))
6980 *quotap *= NSEC_PER_USEC;
6981 else if (!strcmp(tok, "max"))
6982 *quotap = RUNTIME_INF;
6983 else
6984 return -EINVAL;
6985
6986 return 0;
6987}
6988
6989#ifdef CONFIG_CFS_BANDWIDTH
6990static int cpu_max_show(struct seq_file *sf, void *v)
6991{
6992 struct task_group *tg = css_tg(seq_css(sf));
6993
6994 cpu_period_quota_print(sf, tg_get_cfs_period(tg), tg_get_cfs_quota(tg));
6995 return 0;
6996}
6997
6998static ssize_t cpu_max_write(struct kernfs_open_file *of,
6999 char *buf, size_t nbytes, loff_t off)
7000{
7001 struct task_group *tg = css_tg(of_css(of));
7002 u64 period = tg_get_cfs_period(tg);
7003 u64 quota;
7004 int ret;
7005
7006 ret = cpu_period_quota_parse(buf, &period, "a);
7007 if (!ret)
7008 ret = tg_set_cfs_bandwidth(tg, period, quota);
7009 return ret ?: nbytes;
7010}
7011#endif
7012
7013static struct cftype cpu_files[] = {
7014#ifdef CONFIG_FAIR_GROUP_SCHED
7015 {
7016 .name = "weight",
7017 .flags = CFTYPE_NOT_ON_ROOT,
7018 .read_u64 = cpu_weight_read_u64,
7019 .write_u64 = cpu_weight_write_u64,
7020 },
7021 {
7022 .name = "weight.nice",
7023 .flags = CFTYPE_NOT_ON_ROOT,
7024 .read_s64 = cpu_weight_nice_read_s64,
7025 .write_s64 = cpu_weight_nice_write_s64,
7026 },
7027#endif
7028#ifdef CONFIG_CFS_BANDWIDTH
7029 {
7030 .name = "max",
7031 .flags = CFTYPE_NOT_ON_ROOT,
7032 .seq_show = cpu_max_show,
7033 .write = cpu_max_write,
7034 },
7035#endif
7036 { } /* terminate */
7037};
7038
7039struct cgroup_subsys cpu_cgrp_subsys = {
7040 .css_alloc = cpu_cgroup_css_alloc,
7041 .css_online = cpu_cgroup_css_online,
7042 .css_released = cpu_cgroup_css_released,
7043 .css_free = cpu_cgroup_css_free,
7044 .css_extra_stat_show = cpu_extra_stat_show,
7045 .fork = cpu_cgroup_fork,
7046 .can_attach = cpu_cgroup_can_attach,
7047 .attach = cpu_cgroup_attach,
7048 .legacy_cftypes = cpu_legacy_files,
7049 .dfl_cftypes = cpu_files,
7050 .early_init = true,
7051 .threaded = true,
7052};
7053
7054#endif /* CONFIG_CGROUP_SCHED */
7055
7056void dump_cpu_task(int cpu)
7057{
7058 pr_info("Task dump for CPU %d:\n", cpu);
7059 sched_show_task(cpu_curr(cpu));
7060}
7061
7062/*
7063 * Nice levels are multiplicative, with a gentle 10% change for every
7064 * nice level changed. I.e. when a CPU-bound task goes from nice 0 to
7065 * nice 1, it will get ~10% less CPU time than another CPU-bound task
7066 * that remained on nice 0.
7067 *
7068 * The "10% effect" is relative and cumulative: from _any_ nice level,
7069 * if you go up 1 level, it's -10% CPU usage, if you go down 1 level
7070 * it's +10% CPU usage. (to achieve that we use a multiplier of 1.25.
7071 * If a task goes up by ~10% and another task goes down by ~10% then
7072 * the relative distance between them is ~25%.)
7073 */
7074const int sched_prio_to_weight[40] = {
7075 /* -20 */ 88761, 71755, 56483, 46273, 36291,
7076 /* -15 */ 29154, 23254, 18705, 14949, 11916,
7077 /* -10 */ 9548, 7620, 6100, 4904, 3906,
7078 /* -5 */ 3121, 2501, 1991, 1586, 1277,
7079 /* 0 */ 1024, 820, 655, 526, 423,
7080 /* 5 */ 335, 272, 215, 172, 137,
7081 /* 10 */ 110, 87, 70, 56, 45,
7082 /* 15 */ 36, 29, 23, 18, 15,
7083};
7084
7085/*
7086 * Inverse (2^32/x) values of the sched_prio_to_weight[] array, precalculated.
7087 *
7088 * In cases where the weight does not change often, we can use the
7089 * precalculated inverse to speed up arithmetics by turning divisions
7090 * into multiplications:
7091 */
7092const u32 sched_prio_to_wmult[40] = {
7093 /* -20 */ 48388, 59856, 76040, 92818, 118348,
7094 /* -15 */ 147320, 184698, 229616, 287308, 360437,
7095 /* -10 */ 449829, 563644, 704093, 875809, 1099582,
7096 /* -5 */ 1376151, 1717300, 2157191, 2708050, 3363326,
7097 /* 0 */ 4194304, 5237765, 6557202, 8165337, 10153587,
7098 /* 5 */ 12820798, 15790321, 19976592, 24970740, 31350126,
7099 /* 10 */ 39045157, 49367440, 61356676, 76695844, 95443717,
7100 /* 15 */ 119304647, 148102320, 186737708, 238609294, 286331153,
7101};
7102
7103#undef CREATE_TRACE_POINTS