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1/* CPU control.
2 * (C) 2001, 2002, 2003, 2004 Rusty Russell
3 *
4 * This code is licenced under the GPL.
5 */
6#include <linux/proc_fs.h>
7#include <linux/smp.h>
8#include <linux/init.h>
9#include <linux/notifier.h>
10#include <linux/sched.h>
11#include <linux/unistd.h>
12#include <linux/cpu.h>
13#include <linux/oom.h>
14#include <linux/rcupdate.h>
15#include <linux/export.h>
16#include <linux/bug.h>
17#include <linux/kthread.h>
18#include <linux/stop_machine.h>
19#include <linux/mutex.h>
20#include <linux/gfp.h>
21#include <linux/suspend.h>
22#include <linux/lockdep.h>
23
24#include "smpboot.h"
25
26#ifdef CONFIG_SMP
27/* Serializes the updates to cpu_online_mask, cpu_present_mask */
28static DEFINE_MUTEX(cpu_add_remove_lock);
29
30/*
31 * The following two APIs (cpu_maps_update_begin/done) must be used when
32 * attempting to serialize the updates to cpu_online_mask & cpu_present_mask.
33 * The APIs cpu_notifier_register_begin/done() must be used to protect CPU
34 * hotplug callback (un)registration performed using __register_cpu_notifier()
35 * or __unregister_cpu_notifier().
36 */
37void cpu_maps_update_begin(void)
38{
39 mutex_lock(&cpu_add_remove_lock);
40}
41EXPORT_SYMBOL(cpu_notifier_register_begin);
42
43void cpu_maps_update_done(void)
44{
45 mutex_unlock(&cpu_add_remove_lock);
46}
47EXPORT_SYMBOL(cpu_notifier_register_done);
48
49static RAW_NOTIFIER_HEAD(cpu_chain);
50
51/* If set, cpu_up and cpu_down will return -EBUSY and do nothing.
52 * Should always be manipulated under cpu_add_remove_lock
53 */
54static int cpu_hotplug_disabled;
55
56#ifdef CONFIG_HOTPLUG_CPU
57
58static struct {
59 struct task_struct *active_writer;
60 struct mutex lock; /* Synchronizes accesses to refcount, */
61 /*
62 * Also blocks the new readers during
63 * an ongoing cpu hotplug operation.
64 */
65 int refcount;
66
67#ifdef CONFIG_DEBUG_LOCK_ALLOC
68 struct lockdep_map dep_map;
69#endif
70} cpu_hotplug = {
71 .active_writer = NULL,
72 .lock = __MUTEX_INITIALIZER(cpu_hotplug.lock),
73 .refcount = 0,
74#ifdef CONFIG_DEBUG_LOCK_ALLOC
75 .dep_map = {.name = "cpu_hotplug.lock" },
76#endif
77};
78
79/* Lockdep annotations for get/put_online_cpus() and cpu_hotplug_begin/end() */
80#define cpuhp_lock_acquire_read() lock_map_acquire_read(&cpu_hotplug.dep_map)
81#define cpuhp_lock_acquire() lock_map_acquire(&cpu_hotplug.dep_map)
82#define cpuhp_lock_release() lock_map_release(&cpu_hotplug.dep_map)
83
84void get_online_cpus(void)
85{
86 might_sleep();
87 if (cpu_hotplug.active_writer == current)
88 return;
89 cpuhp_lock_acquire_read();
90 mutex_lock(&cpu_hotplug.lock);
91 cpu_hotplug.refcount++;
92 mutex_unlock(&cpu_hotplug.lock);
93
94}
95EXPORT_SYMBOL_GPL(get_online_cpus);
96
97void put_online_cpus(void)
98{
99 if (cpu_hotplug.active_writer == current)
100 return;
101 mutex_lock(&cpu_hotplug.lock);
102
103 if (WARN_ON(!cpu_hotplug.refcount))
104 cpu_hotplug.refcount++; /* try to fix things up */
105
106 if (!--cpu_hotplug.refcount && unlikely(cpu_hotplug.active_writer))
107 wake_up_process(cpu_hotplug.active_writer);
108 mutex_unlock(&cpu_hotplug.lock);
109 cpuhp_lock_release();
110
111}
112EXPORT_SYMBOL_GPL(put_online_cpus);
113
114/*
115 * This ensures that the hotplug operation can begin only when the
116 * refcount goes to zero.
117 *
118 * Note that during a cpu-hotplug operation, the new readers, if any,
119 * will be blocked by the cpu_hotplug.lock
120 *
121 * Since cpu_hotplug_begin() is always called after invoking
122 * cpu_maps_update_begin(), we can be sure that only one writer is active.
123 *
124 * Note that theoretically, there is a possibility of a livelock:
125 * - Refcount goes to zero, last reader wakes up the sleeping
126 * writer.
127 * - Last reader unlocks the cpu_hotplug.lock.
128 * - A new reader arrives at this moment, bumps up the refcount.
129 * - The writer acquires the cpu_hotplug.lock finds the refcount
130 * non zero and goes to sleep again.
131 *
132 * However, this is very difficult to achieve in practice since
133 * get_online_cpus() not an api which is called all that often.
134 *
135 */
136void cpu_hotplug_begin(void)
137{
138 cpu_hotplug.active_writer = current;
139
140 cpuhp_lock_acquire();
141 for (;;) {
142 mutex_lock(&cpu_hotplug.lock);
143 if (likely(!cpu_hotplug.refcount))
144 break;
145 __set_current_state(TASK_UNINTERRUPTIBLE);
146 mutex_unlock(&cpu_hotplug.lock);
147 schedule();
148 }
149}
150
151void cpu_hotplug_done(void)
152{
153 cpu_hotplug.active_writer = NULL;
154 mutex_unlock(&cpu_hotplug.lock);
155 cpuhp_lock_release();
156}
157
158/*
159 * Wait for currently running CPU hotplug operations to complete (if any) and
160 * disable future CPU hotplug (from sysfs). The 'cpu_add_remove_lock' protects
161 * the 'cpu_hotplug_disabled' flag. The same lock is also acquired by the
162 * hotplug path before performing hotplug operations. So acquiring that lock
163 * guarantees mutual exclusion from any currently running hotplug operations.
164 */
165void cpu_hotplug_disable(void)
166{
167 cpu_maps_update_begin();
168 cpu_hotplug_disabled = 1;
169 cpu_maps_update_done();
170}
171
172void cpu_hotplug_enable(void)
173{
174 cpu_maps_update_begin();
175 cpu_hotplug_disabled = 0;
176 cpu_maps_update_done();
177}
178
179#endif /* CONFIG_HOTPLUG_CPU */
180
181/* Need to know about CPUs going up/down? */
182int __ref register_cpu_notifier(struct notifier_block *nb)
183{
184 int ret;
185 cpu_maps_update_begin();
186 ret = raw_notifier_chain_register(&cpu_chain, nb);
187 cpu_maps_update_done();
188 return ret;
189}
190
191int __ref __register_cpu_notifier(struct notifier_block *nb)
192{
193 return raw_notifier_chain_register(&cpu_chain, nb);
194}
195
196static int __cpu_notify(unsigned long val, void *v, int nr_to_call,
197 int *nr_calls)
198{
199 int ret;
200
201 ret = __raw_notifier_call_chain(&cpu_chain, val, v, nr_to_call,
202 nr_calls);
203
204 return notifier_to_errno(ret);
205}
206
207static int cpu_notify(unsigned long val, void *v)
208{
209 return __cpu_notify(val, v, -1, NULL);
210}
211
212#ifdef CONFIG_HOTPLUG_CPU
213
214static void cpu_notify_nofail(unsigned long val, void *v)
215{
216 BUG_ON(cpu_notify(val, v));
217}
218EXPORT_SYMBOL(register_cpu_notifier);
219EXPORT_SYMBOL(__register_cpu_notifier);
220
221void __ref unregister_cpu_notifier(struct notifier_block *nb)
222{
223 cpu_maps_update_begin();
224 raw_notifier_chain_unregister(&cpu_chain, nb);
225 cpu_maps_update_done();
226}
227EXPORT_SYMBOL(unregister_cpu_notifier);
228
229void __ref __unregister_cpu_notifier(struct notifier_block *nb)
230{
231 raw_notifier_chain_unregister(&cpu_chain, nb);
232}
233EXPORT_SYMBOL(__unregister_cpu_notifier);
234
235/**
236 * clear_tasks_mm_cpumask - Safely clear tasks' mm_cpumask for a CPU
237 * @cpu: a CPU id
238 *
239 * This function walks all processes, finds a valid mm struct for each one and
240 * then clears a corresponding bit in mm's cpumask. While this all sounds
241 * trivial, there are various non-obvious corner cases, which this function
242 * tries to solve in a safe manner.
243 *
244 * Also note that the function uses a somewhat relaxed locking scheme, so it may
245 * be called only for an already offlined CPU.
246 */
247void clear_tasks_mm_cpumask(int cpu)
248{
249 struct task_struct *p;
250
251 /*
252 * This function is called after the cpu is taken down and marked
253 * offline, so its not like new tasks will ever get this cpu set in
254 * their mm mask. -- Peter Zijlstra
255 * Thus, we may use rcu_read_lock() here, instead of grabbing
256 * full-fledged tasklist_lock.
257 */
258 WARN_ON(cpu_online(cpu));
259 rcu_read_lock();
260 for_each_process(p) {
261 struct task_struct *t;
262
263 /*
264 * Main thread might exit, but other threads may still have
265 * a valid mm. Find one.
266 */
267 t = find_lock_task_mm(p);
268 if (!t)
269 continue;
270 cpumask_clear_cpu(cpu, mm_cpumask(t->mm));
271 task_unlock(t);
272 }
273 rcu_read_unlock();
274}
275
276static inline void check_for_tasks(int cpu)
277{
278 struct task_struct *p;
279 cputime_t utime, stime;
280
281 write_lock_irq(&tasklist_lock);
282 for_each_process(p) {
283 task_cputime(p, &utime, &stime);
284 if (task_cpu(p) == cpu && p->state == TASK_RUNNING &&
285 (utime || stime))
286 printk(KERN_WARNING "Task %s (pid = %d) is on cpu %d "
287 "(state = %ld, flags = %x)\n",
288 p->comm, task_pid_nr(p), cpu,
289 p->state, p->flags);
290 }
291 write_unlock_irq(&tasklist_lock);
292}
293
294struct take_cpu_down_param {
295 unsigned long mod;
296 void *hcpu;
297};
298
299/* Take this CPU down. */
300static int __ref take_cpu_down(void *_param)
301{
302 struct take_cpu_down_param *param = _param;
303 int err;
304
305 /* Ensure this CPU doesn't handle any more interrupts. */
306 err = __cpu_disable();
307 if (err < 0)
308 return err;
309
310 cpu_notify(CPU_DYING | param->mod, param->hcpu);
311 /* Park the stopper thread */
312 kthread_park(current);
313 return 0;
314}
315
316/* Requires cpu_add_remove_lock to be held */
317static int __ref _cpu_down(unsigned int cpu, int tasks_frozen)
318{
319 int err, nr_calls = 0;
320 void *hcpu = (void *)(long)cpu;
321 unsigned long mod = tasks_frozen ? CPU_TASKS_FROZEN : 0;
322 struct take_cpu_down_param tcd_param = {
323 .mod = mod,
324 .hcpu = hcpu,
325 };
326
327 if (num_online_cpus() == 1)
328 return -EBUSY;
329
330 if (!cpu_online(cpu))
331 return -EINVAL;
332
333 cpu_hotplug_begin();
334
335 err = __cpu_notify(CPU_DOWN_PREPARE | mod, hcpu, -1, &nr_calls);
336 if (err) {
337 nr_calls--;
338 __cpu_notify(CPU_DOWN_FAILED | mod, hcpu, nr_calls, NULL);
339 printk("%s: attempt to take down CPU %u failed\n",
340 __func__, cpu);
341 goto out_release;
342 }
343
344 /*
345 * By now we've cleared cpu_active_mask, wait for all preempt-disabled
346 * and RCU users of this state to go away such that all new such users
347 * will observe it.
348 *
349 * For CONFIG_PREEMPT we have preemptible RCU and its sync_rcu() might
350 * not imply sync_sched(), so explicitly call both.
351 *
352 * Do sync before park smpboot threads to take care the rcu boost case.
353 */
354#ifdef CONFIG_PREEMPT
355 synchronize_sched();
356#endif
357 synchronize_rcu();
358
359 smpboot_park_threads(cpu);
360
361 /*
362 * So now all preempt/rcu users must observe !cpu_active().
363 */
364
365 err = __stop_machine(take_cpu_down, &tcd_param, cpumask_of(cpu));
366 if (err) {
367 /* CPU didn't die: tell everyone. Can't complain. */
368 smpboot_unpark_threads(cpu);
369 cpu_notify_nofail(CPU_DOWN_FAILED | mod, hcpu);
370 goto out_release;
371 }
372 BUG_ON(cpu_online(cpu));
373
374 /*
375 * The migration_call() CPU_DYING callback will have removed all
376 * runnable tasks from the cpu, there's only the idle task left now
377 * that the migration thread is done doing the stop_machine thing.
378 *
379 * Wait for the stop thread to go away.
380 */
381 while (!idle_cpu(cpu))
382 cpu_relax();
383
384 /* This actually kills the CPU. */
385 __cpu_die(cpu);
386
387 /* CPU is completely dead: tell everyone. Too late to complain. */
388 cpu_notify_nofail(CPU_DEAD | mod, hcpu);
389
390 check_for_tasks(cpu);
391
392out_release:
393 cpu_hotplug_done();
394 if (!err)
395 cpu_notify_nofail(CPU_POST_DEAD | mod, hcpu);
396 return err;
397}
398
399int __ref cpu_down(unsigned int cpu)
400{
401 int err;
402
403 cpu_maps_update_begin();
404
405 if (cpu_hotplug_disabled) {
406 err = -EBUSY;
407 goto out;
408 }
409
410 err = _cpu_down(cpu, 0);
411
412out:
413 cpu_maps_update_done();
414 return err;
415}
416EXPORT_SYMBOL(cpu_down);
417#endif /*CONFIG_HOTPLUG_CPU*/
418
419/* Requires cpu_add_remove_lock to be held */
420static int _cpu_up(unsigned int cpu, int tasks_frozen)
421{
422 int ret, nr_calls = 0;
423 void *hcpu = (void *)(long)cpu;
424 unsigned long mod = tasks_frozen ? CPU_TASKS_FROZEN : 0;
425 struct task_struct *idle;
426
427 cpu_hotplug_begin();
428
429 if (cpu_online(cpu) || !cpu_present(cpu)) {
430 ret = -EINVAL;
431 goto out;
432 }
433
434 idle = idle_thread_get(cpu);
435 if (IS_ERR(idle)) {
436 ret = PTR_ERR(idle);
437 goto out;
438 }
439
440 ret = smpboot_create_threads(cpu);
441 if (ret)
442 goto out;
443
444 ret = __cpu_notify(CPU_UP_PREPARE | mod, hcpu, -1, &nr_calls);
445 if (ret) {
446 nr_calls--;
447 printk(KERN_WARNING "%s: attempt to bring up CPU %u failed\n",
448 __func__, cpu);
449 goto out_notify;
450 }
451
452 /* Arch-specific enabling code. */
453 ret = __cpu_up(cpu, idle);
454 if (ret != 0)
455 goto out_notify;
456 BUG_ON(!cpu_online(cpu));
457
458 /* Wake the per cpu threads */
459 smpboot_unpark_threads(cpu);
460
461 /* Now call notifier in preparation. */
462 cpu_notify(CPU_ONLINE | mod, hcpu);
463
464out_notify:
465 if (ret != 0)
466 __cpu_notify(CPU_UP_CANCELED | mod, hcpu, nr_calls, NULL);
467out:
468 cpu_hotplug_done();
469
470 return ret;
471}
472
473int cpu_up(unsigned int cpu)
474{
475 int err = 0;
476
477 if (!cpu_possible(cpu)) {
478 printk(KERN_ERR "can't online cpu %d because it is not "
479 "configured as may-hotadd at boot time\n", cpu);
480#if defined(CONFIG_IA64)
481 printk(KERN_ERR "please check additional_cpus= boot "
482 "parameter\n");
483#endif
484 return -EINVAL;
485 }
486
487 err = try_online_node(cpu_to_node(cpu));
488 if (err)
489 return err;
490
491 cpu_maps_update_begin();
492
493 if (cpu_hotplug_disabled) {
494 err = -EBUSY;
495 goto out;
496 }
497
498 err = _cpu_up(cpu, 0);
499
500out:
501 cpu_maps_update_done();
502 return err;
503}
504EXPORT_SYMBOL_GPL(cpu_up);
505
506#ifdef CONFIG_PM_SLEEP_SMP
507static cpumask_var_t frozen_cpus;
508
509int disable_nonboot_cpus(void)
510{
511 int cpu, first_cpu, error = 0;
512
513 cpu_maps_update_begin();
514 first_cpu = cpumask_first(cpu_online_mask);
515 /*
516 * We take down all of the non-boot CPUs in one shot to avoid races
517 * with the userspace trying to use the CPU hotplug at the same time
518 */
519 cpumask_clear(frozen_cpus);
520
521 printk("Disabling non-boot CPUs ...\n");
522 for_each_online_cpu(cpu) {
523 if (cpu == first_cpu)
524 continue;
525 error = _cpu_down(cpu, 1);
526 if (!error)
527 cpumask_set_cpu(cpu, frozen_cpus);
528 else {
529 printk(KERN_ERR "Error taking CPU%d down: %d\n",
530 cpu, error);
531 break;
532 }
533 }
534
535 if (!error) {
536 BUG_ON(num_online_cpus() > 1);
537 /* Make sure the CPUs won't be enabled by someone else */
538 cpu_hotplug_disabled = 1;
539 } else {
540 printk(KERN_ERR "Non-boot CPUs are not disabled\n");
541 }
542 cpu_maps_update_done();
543 return error;
544}
545
546void __weak arch_enable_nonboot_cpus_begin(void)
547{
548}
549
550void __weak arch_enable_nonboot_cpus_end(void)
551{
552}
553
554void __ref enable_nonboot_cpus(void)
555{
556 int cpu, error;
557
558 /* Allow everyone to use the CPU hotplug again */
559 cpu_maps_update_begin();
560 cpu_hotplug_disabled = 0;
561 if (cpumask_empty(frozen_cpus))
562 goto out;
563
564 printk(KERN_INFO "Enabling non-boot CPUs ...\n");
565
566 arch_enable_nonboot_cpus_begin();
567
568 for_each_cpu(cpu, frozen_cpus) {
569 error = _cpu_up(cpu, 1);
570 if (!error) {
571 printk(KERN_INFO "CPU%d is up\n", cpu);
572 continue;
573 }
574 printk(KERN_WARNING "Error taking CPU%d up: %d\n", cpu, error);
575 }
576
577 arch_enable_nonboot_cpus_end();
578
579 cpumask_clear(frozen_cpus);
580out:
581 cpu_maps_update_done();
582}
583
584static int __init alloc_frozen_cpus(void)
585{
586 if (!alloc_cpumask_var(&frozen_cpus, GFP_KERNEL|__GFP_ZERO))
587 return -ENOMEM;
588 return 0;
589}
590core_initcall(alloc_frozen_cpus);
591
592/*
593 * When callbacks for CPU hotplug notifications are being executed, we must
594 * ensure that the state of the system with respect to the tasks being frozen
595 * or not, as reported by the notification, remains unchanged *throughout the
596 * duration* of the execution of the callbacks.
597 * Hence we need to prevent the freezer from racing with regular CPU hotplug.
598 *
599 * This synchronization is implemented by mutually excluding regular CPU
600 * hotplug and Suspend/Hibernate call paths by hooking onto the Suspend/
601 * Hibernate notifications.
602 */
603static int
604cpu_hotplug_pm_callback(struct notifier_block *nb,
605 unsigned long action, void *ptr)
606{
607 switch (action) {
608
609 case PM_SUSPEND_PREPARE:
610 case PM_HIBERNATION_PREPARE:
611 cpu_hotplug_disable();
612 break;
613
614 case PM_POST_SUSPEND:
615 case PM_POST_HIBERNATION:
616 cpu_hotplug_enable();
617 break;
618
619 default:
620 return NOTIFY_DONE;
621 }
622
623 return NOTIFY_OK;
624}
625
626
627static int __init cpu_hotplug_pm_sync_init(void)
628{
629 /*
630 * cpu_hotplug_pm_callback has higher priority than x86
631 * bsp_pm_callback which depends on cpu_hotplug_pm_callback
632 * to disable cpu hotplug to avoid cpu hotplug race.
633 */
634 pm_notifier(cpu_hotplug_pm_callback, 0);
635 return 0;
636}
637core_initcall(cpu_hotplug_pm_sync_init);
638
639#endif /* CONFIG_PM_SLEEP_SMP */
640
641/**
642 * notify_cpu_starting(cpu) - call the CPU_STARTING notifiers
643 * @cpu: cpu that just started
644 *
645 * This function calls the cpu_chain notifiers with CPU_STARTING.
646 * It must be called by the arch code on the new cpu, before the new cpu
647 * enables interrupts and before the "boot" cpu returns from __cpu_up().
648 */
649void notify_cpu_starting(unsigned int cpu)
650{
651 unsigned long val = CPU_STARTING;
652
653#ifdef CONFIG_PM_SLEEP_SMP
654 if (frozen_cpus != NULL && cpumask_test_cpu(cpu, frozen_cpus))
655 val = CPU_STARTING_FROZEN;
656#endif /* CONFIG_PM_SLEEP_SMP */
657 cpu_notify(val, (void *)(long)cpu);
658}
659
660#endif /* CONFIG_SMP */
661
662/*
663 * cpu_bit_bitmap[] is a special, "compressed" data structure that
664 * represents all NR_CPUS bits binary values of 1<<nr.
665 *
666 * It is used by cpumask_of() to get a constant address to a CPU
667 * mask value that has a single bit set only.
668 */
669
670/* cpu_bit_bitmap[0] is empty - so we can back into it */
671#define MASK_DECLARE_1(x) [x+1][0] = (1UL << (x))
672#define MASK_DECLARE_2(x) MASK_DECLARE_1(x), MASK_DECLARE_1(x+1)
673#define MASK_DECLARE_4(x) MASK_DECLARE_2(x), MASK_DECLARE_2(x+2)
674#define MASK_DECLARE_8(x) MASK_DECLARE_4(x), MASK_DECLARE_4(x+4)
675
676const unsigned long cpu_bit_bitmap[BITS_PER_LONG+1][BITS_TO_LONGS(NR_CPUS)] = {
677
678 MASK_DECLARE_8(0), MASK_DECLARE_8(8),
679 MASK_DECLARE_8(16), MASK_DECLARE_8(24),
680#if BITS_PER_LONG > 32
681 MASK_DECLARE_8(32), MASK_DECLARE_8(40),
682 MASK_DECLARE_8(48), MASK_DECLARE_8(56),
683#endif
684};
685EXPORT_SYMBOL_GPL(cpu_bit_bitmap);
686
687const DECLARE_BITMAP(cpu_all_bits, NR_CPUS) = CPU_BITS_ALL;
688EXPORT_SYMBOL(cpu_all_bits);
689
690#ifdef CONFIG_INIT_ALL_POSSIBLE
691static DECLARE_BITMAP(cpu_possible_bits, CONFIG_NR_CPUS) __read_mostly
692 = CPU_BITS_ALL;
693#else
694static DECLARE_BITMAP(cpu_possible_bits, CONFIG_NR_CPUS) __read_mostly;
695#endif
696const struct cpumask *const cpu_possible_mask = to_cpumask(cpu_possible_bits);
697EXPORT_SYMBOL(cpu_possible_mask);
698
699static DECLARE_BITMAP(cpu_online_bits, CONFIG_NR_CPUS) __read_mostly;
700const struct cpumask *const cpu_online_mask = to_cpumask(cpu_online_bits);
701EXPORT_SYMBOL(cpu_online_mask);
702
703static DECLARE_BITMAP(cpu_present_bits, CONFIG_NR_CPUS) __read_mostly;
704const struct cpumask *const cpu_present_mask = to_cpumask(cpu_present_bits);
705EXPORT_SYMBOL(cpu_present_mask);
706
707static DECLARE_BITMAP(cpu_active_bits, CONFIG_NR_CPUS) __read_mostly;
708const struct cpumask *const cpu_active_mask = to_cpumask(cpu_active_bits);
709EXPORT_SYMBOL(cpu_active_mask);
710
711void set_cpu_possible(unsigned int cpu, bool possible)
712{
713 if (possible)
714 cpumask_set_cpu(cpu, to_cpumask(cpu_possible_bits));
715 else
716 cpumask_clear_cpu(cpu, to_cpumask(cpu_possible_bits));
717}
718
719void set_cpu_present(unsigned int cpu, bool present)
720{
721 if (present)
722 cpumask_set_cpu(cpu, to_cpumask(cpu_present_bits));
723 else
724 cpumask_clear_cpu(cpu, to_cpumask(cpu_present_bits));
725}
726
727void set_cpu_online(unsigned int cpu, bool online)
728{
729 if (online) {
730 cpumask_set_cpu(cpu, to_cpumask(cpu_online_bits));
731 cpumask_set_cpu(cpu, to_cpumask(cpu_active_bits));
732 } else {
733 cpumask_clear_cpu(cpu, to_cpumask(cpu_online_bits));
734 }
735}
736
737void set_cpu_active(unsigned int cpu, bool active)
738{
739 if (active)
740 cpumask_set_cpu(cpu, to_cpumask(cpu_active_bits));
741 else
742 cpumask_clear_cpu(cpu, to_cpumask(cpu_active_bits));
743}
744
745void init_cpu_present(const struct cpumask *src)
746{
747 cpumask_copy(to_cpumask(cpu_present_bits), src);
748}
749
750void init_cpu_possible(const struct cpumask *src)
751{
752 cpumask_copy(to_cpumask(cpu_possible_bits), src);
753}
754
755void init_cpu_online(const struct cpumask *src)
756{
757 cpumask_copy(to_cpumask(cpu_online_bits), src);
758}
1/* CPU control.
2 * (C) 2001, 2002, 2003, 2004 Rusty Russell
3 *
4 * This code is licenced under the GPL.
5 */
6#include <linux/proc_fs.h>
7#include <linux/smp.h>
8#include <linux/init.h>
9#include <linux/notifier.h>
10#include <linux/sched.h>
11#include <linux/unistd.h>
12#include <linux/cpu.h>
13#include <linux/oom.h>
14#include <linux/rcupdate.h>
15#include <linux/export.h>
16#include <linux/bug.h>
17#include <linux/kthread.h>
18#include <linux/stop_machine.h>
19#include <linux/mutex.h>
20#include <linux/gfp.h>
21#include <linux/suspend.h>
22
23#include "smpboot.h"
24
25#ifdef CONFIG_SMP
26/* Serializes the updates to cpu_online_mask, cpu_present_mask */
27static DEFINE_MUTEX(cpu_add_remove_lock);
28
29/*
30 * The following two API's must be used when attempting
31 * to serialize the updates to cpu_online_mask, cpu_present_mask.
32 */
33void cpu_maps_update_begin(void)
34{
35 mutex_lock(&cpu_add_remove_lock);
36}
37
38void cpu_maps_update_done(void)
39{
40 mutex_unlock(&cpu_add_remove_lock);
41}
42
43static RAW_NOTIFIER_HEAD(cpu_chain);
44
45/* If set, cpu_up and cpu_down will return -EBUSY and do nothing.
46 * Should always be manipulated under cpu_add_remove_lock
47 */
48static int cpu_hotplug_disabled;
49
50#ifdef CONFIG_HOTPLUG_CPU
51
52static struct {
53 struct task_struct *active_writer;
54 struct mutex lock; /* Synchronizes accesses to refcount, */
55 /*
56 * Also blocks the new readers during
57 * an ongoing cpu hotplug operation.
58 */
59 int refcount;
60} cpu_hotplug = {
61 .active_writer = NULL,
62 .lock = __MUTEX_INITIALIZER(cpu_hotplug.lock),
63 .refcount = 0,
64};
65
66void get_online_cpus(void)
67{
68 might_sleep();
69 if (cpu_hotplug.active_writer == current)
70 return;
71 mutex_lock(&cpu_hotplug.lock);
72 cpu_hotplug.refcount++;
73 mutex_unlock(&cpu_hotplug.lock);
74
75}
76EXPORT_SYMBOL_GPL(get_online_cpus);
77
78void put_online_cpus(void)
79{
80 if (cpu_hotplug.active_writer == current)
81 return;
82 mutex_lock(&cpu_hotplug.lock);
83 if (!--cpu_hotplug.refcount && unlikely(cpu_hotplug.active_writer))
84 wake_up_process(cpu_hotplug.active_writer);
85 mutex_unlock(&cpu_hotplug.lock);
86
87}
88EXPORT_SYMBOL_GPL(put_online_cpus);
89
90/*
91 * This ensures that the hotplug operation can begin only when the
92 * refcount goes to zero.
93 *
94 * Note that during a cpu-hotplug operation, the new readers, if any,
95 * will be blocked by the cpu_hotplug.lock
96 *
97 * Since cpu_hotplug_begin() is always called after invoking
98 * cpu_maps_update_begin(), we can be sure that only one writer is active.
99 *
100 * Note that theoretically, there is a possibility of a livelock:
101 * - Refcount goes to zero, last reader wakes up the sleeping
102 * writer.
103 * - Last reader unlocks the cpu_hotplug.lock.
104 * - A new reader arrives at this moment, bumps up the refcount.
105 * - The writer acquires the cpu_hotplug.lock finds the refcount
106 * non zero and goes to sleep again.
107 *
108 * However, this is very difficult to achieve in practice since
109 * get_online_cpus() not an api which is called all that often.
110 *
111 */
112static void cpu_hotplug_begin(void)
113{
114 cpu_hotplug.active_writer = current;
115
116 for (;;) {
117 mutex_lock(&cpu_hotplug.lock);
118 if (likely(!cpu_hotplug.refcount))
119 break;
120 __set_current_state(TASK_UNINTERRUPTIBLE);
121 mutex_unlock(&cpu_hotplug.lock);
122 schedule();
123 }
124}
125
126static void cpu_hotplug_done(void)
127{
128 cpu_hotplug.active_writer = NULL;
129 mutex_unlock(&cpu_hotplug.lock);
130}
131
132#else /* #if CONFIG_HOTPLUG_CPU */
133static void cpu_hotplug_begin(void) {}
134static void cpu_hotplug_done(void) {}
135#endif /* #else #if CONFIG_HOTPLUG_CPU */
136
137/* Need to know about CPUs going up/down? */
138int __ref register_cpu_notifier(struct notifier_block *nb)
139{
140 int ret;
141 cpu_maps_update_begin();
142 ret = raw_notifier_chain_register(&cpu_chain, nb);
143 cpu_maps_update_done();
144 return ret;
145}
146
147static int __cpu_notify(unsigned long val, void *v, int nr_to_call,
148 int *nr_calls)
149{
150 int ret;
151
152 ret = __raw_notifier_call_chain(&cpu_chain, val, v, nr_to_call,
153 nr_calls);
154
155 return notifier_to_errno(ret);
156}
157
158static int cpu_notify(unsigned long val, void *v)
159{
160 return __cpu_notify(val, v, -1, NULL);
161}
162
163#ifdef CONFIG_HOTPLUG_CPU
164
165static void cpu_notify_nofail(unsigned long val, void *v)
166{
167 BUG_ON(cpu_notify(val, v));
168}
169EXPORT_SYMBOL(register_cpu_notifier);
170
171void __ref unregister_cpu_notifier(struct notifier_block *nb)
172{
173 cpu_maps_update_begin();
174 raw_notifier_chain_unregister(&cpu_chain, nb);
175 cpu_maps_update_done();
176}
177EXPORT_SYMBOL(unregister_cpu_notifier);
178
179/**
180 * clear_tasks_mm_cpumask - Safely clear tasks' mm_cpumask for a CPU
181 * @cpu: a CPU id
182 *
183 * This function walks all processes, finds a valid mm struct for each one and
184 * then clears a corresponding bit in mm's cpumask. While this all sounds
185 * trivial, there are various non-obvious corner cases, which this function
186 * tries to solve in a safe manner.
187 *
188 * Also note that the function uses a somewhat relaxed locking scheme, so it may
189 * be called only for an already offlined CPU.
190 */
191void clear_tasks_mm_cpumask(int cpu)
192{
193 struct task_struct *p;
194
195 /*
196 * This function is called after the cpu is taken down and marked
197 * offline, so its not like new tasks will ever get this cpu set in
198 * their mm mask. -- Peter Zijlstra
199 * Thus, we may use rcu_read_lock() here, instead of grabbing
200 * full-fledged tasklist_lock.
201 */
202 WARN_ON(cpu_online(cpu));
203 rcu_read_lock();
204 for_each_process(p) {
205 struct task_struct *t;
206
207 /*
208 * Main thread might exit, but other threads may still have
209 * a valid mm. Find one.
210 */
211 t = find_lock_task_mm(p);
212 if (!t)
213 continue;
214 cpumask_clear_cpu(cpu, mm_cpumask(t->mm));
215 task_unlock(t);
216 }
217 rcu_read_unlock();
218}
219
220static inline void check_for_tasks(int cpu)
221{
222 struct task_struct *p;
223
224 write_lock_irq(&tasklist_lock);
225 for_each_process(p) {
226 if (task_cpu(p) == cpu && p->state == TASK_RUNNING &&
227 (p->utime || p->stime))
228 printk(KERN_WARNING "Task %s (pid = %d) is on cpu %d "
229 "(state = %ld, flags = %x)\n",
230 p->comm, task_pid_nr(p), cpu,
231 p->state, p->flags);
232 }
233 write_unlock_irq(&tasklist_lock);
234}
235
236struct take_cpu_down_param {
237 unsigned long mod;
238 void *hcpu;
239};
240
241/* Take this CPU down. */
242static int __ref take_cpu_down(void *_param)
243{
244 struct take_cpu_down_param *param = _param;
245 int err;
246
247 /* Ensure this CPU doesn't handle any more interrupts. */
248 err = __cpu_disable();
249 if (err < 0)
250 return err;
251
252 cpu_notify(CPU_DYING | param->mod, param->hcpu);
253 return 0;
254}
255
256/* Requires cpu_add_remove_lock to be held */
257static int __ref _cpu_down(unsigned int cpu, int tasks_frozen)
258{
259 int err, nr_calls = 0;
260 void *hcpu = (void *)(long)cpu;
261 unsigned long mod = tasks_frozen ? CPU_TASKS_FROZEN : 0;
262 struct take_cpu_down_param tcd_param = {
263 .mod = mod,
264 .hcpu = hcpu,
265 };
266
267 if (num_online_cpus() == 1)
268 return -EBUSY;
269
270 if (!cpu_online(cpu))
271 return -EINVAL;
272
273 cpu_hotplug_begin();
274
275 err = __cpu_notify(CPU_DOWN_PREPARE | mod, hcpu, -1, &nr_calls);
276 if (err) {
277 nr_calls--;
278 __cpu_notify(CPU_DOWN_FAILED | mod, hcpu, nr_calls, NULL);
279 printk("%s: attempt to take down CPU %u failed\n",
280 __func__, cpu);
281 goto out_release;
282 }
283
284 err = __stop_machine(take_cpu_down, &tcd_param, cpumask_of(cpu));
285 if (err) {
286 /* CPU didn't die: tell everyone. Can't complain. */
287 cpu_notify_nofail(CPU_DOWN_FAILED | mod, hcpu);
288
289 goto out_release;
290 }
291 BUG_ON(cpu_online(cpu));
292
293 /*
294 * The migration_call() CPU_DYING callback will have removed all
295 * runnable tasks from the cpu, there's only the idle task left now
296 * that the migration thread is done doing the stop_machine thing.
297 *
298 * Wait for the stop thread to go away.
299 */
300 while (!idle_cpu(cpu))
301 cpu_relax();
302
303 /* This actually kills the CPU. */
304 __cpu_die(cpu);
305
306 /* CPU is completely dead: tell everyone. Too late to complain. */
307 cpu_notify_nofail(CPU_DEAD | mod, hcpu);
308
309 check_for_tasks(cpu);
310
311out_release:
312 cpu_hotplug_done();
313 if (!err)
314 cpu_notify_nofail(CPU_POST_DEAD | mod, hcpu);
315 return err;
316}
317
318int __ref cpu_down(unsigned int cpu)
319{
320 int err;
321
322 cpu_maps_update_begin();
323
324 if (cpu_hotplug_disabled) {
325 err = -EBUSY;
326 goto out;
327 }
328
329 err = _cpu_down(cpu, 0);
330
331out:
332 cpu_maps_update_done();
333 return err;
334}
335EXPORT_SYMBOL(cpu_down);
336#endif /*CONFIG_HOTPLUG_CPU*/
337
338/* Requires cpu_add_remove_lock to be held */
339static int __cpuinit _cpu_up(unsigned int cpu, int tasks_frozen)
340{
341 int ret, nr_calls = 0;
342 void *hcpu = (void *)(long)cpu;
343 unsigned long mod = tasks_frozen ? CPU_TASKS_FROZEN : 0;
344 struct task_struct *idle;
345
346 if (cpu_online(cpu) || !cpu_present(cpu))
347 return -EINVAL;
348
349 cpu_hotplug_begin();
350
351 idle = idle_thread_get(cpu);
352 if (IS_ERR(idle)) {
353 ret = PTR_ERR(idle);
354 goto out;
355 }
356
357 ret = __cpu_notify(CPU_UP_PREPARE | mod, hcpu, -1, &nr_calls);
358 if (ret) {
359 nr_calls--;
360 printk(KERN_WARNING "%s: attempt to bring up CPU %u failed\n",
361 __func__, cpu);
362 goto out_notify;
363 }
364
365 /* Arch-specific enabling code. */
366 ret = __cpu_up(cpu, idle);
367 if (ret != 0)
368 goto out_notify;
369 BUG_ON(!cpu_online(cpu));
370
371 /* Now call notifier in preparation. */
372 cpu_notify(CPU_ONLINE | mod, hcpu);
373
374out_notify:
375 if (ret != 0)
376 __cpu_notify(CPU_UP_CANCELED | mod, hcpu, nr_calls, NULL);
377out:
378 cpu_hotplug_done();
379
380 return ret;
381}
382
383int __cpuinit cpu_up(unsigned int cpu)
384{
385 int err = 0;
386
387#ifdef CONFIG_MEMORY_HOTPLUG
388 int nid;
389 pg_data_t *pgdat;
390#endif
391
392 if (!cpu_possible(cpu)) {
393 printk(KERN_ERR "can't online cpu %d because it is not "
394 "configured as may-hotadd at boot time\n", cpu);
395#if defined(CONFIG_IA64)
396 printk(KERN_ERR "please check additional_cpus= boot "
397 "parameter\n");
398#endif
399 return -EINVAL;
400 }
401
402#ifdef CONFIG_MEMORY_HOTPLUG
403 nid = cpu_to_node(cpu);
404 if (!node_online(nid)) {
405 err = mem_online_node(nid);
406 if (err)
407 return err;
408 }
409
410 pgdat = NODE_DATA(nid);
411 if (!pgdat) {
412 printk(KERN_ERR
413 "Can't online cpu %d due to NULL pgdat\n", cpu);
414 return -ENOMEM;
415 }
416
417 if (pgdat->node_zonelists->_zonerefs->zone == NULL) {
418 mutex_lock(&zonelists_mutex);
419 build_all_zonelists(NULL);
420 mutex_unlock(&zonelists_mutex);
421 }
422#endif
423
424 cpu_maps_update_begin();
425
426 if (cpu_hotplug_disabled) {
427 err = -EBUSY;
428 goto out;
429 }
430
431 err = _cpu_up(cpu, 0);
432
433out:
434 cpu_maps_update_done();
435 return err;
436}
437EXPORT_SYMBOL_GPL(cpu_up);
438
439#ifdef CONFIG_PM_SLEEP_SMP
440static cpumask_var_t frozen_cpus;
441
442void __weak arch_disable_nonboot_cpus_begin(void)
443{
444}
445
446void __weak arch_disable_nonboot_cpus_end(void)
447{
448}
449
450int disable_nonboot_cpus(void)
451{
452 int cpu, first_cpu, error = 0;
453
454 cpu_maps_update_begin();
455 first_cpu = cpumask_first(cpu_online_mask);
456 /*
457 * We take down all of the non-boot CPUs in one shot to avoid races
458 * with the userspace trying to use the CPU hotplug at the same time
459 */
460 cpumask_clear(frozen_cpus);
461 arch_disable_nonboot_cpus_begin();
462
463 printk("Disabling non-boot CPUs ...\n");
464 for_each_online_cpu(cpu) {
465 if (cpu == first_cpu)
466 continue;
467 error = _cpu_down(cpu, 1);
468 if (!error)
469 cpumask_set_cpu(cpu, frozen_cpus);
470 else {
471 printk(KERN_ERR "Error taking CPU%d down: %d\n",
472 cpu, error);
473 break;
474 }
475 }
476
477 arch_disable_nonboot_cpus_end();
478
479 if (!error) {
480 BUG_ON(num_online_cpus() > 1);
481 /* Make sure the CPUs won't be enabled by someone else */
482 cpu_hotplug_disabled = 1;
483 } else {
484 printk(KERN_ERR "Non-boot CPUs are not disabled\n");
485 }
486 cpu_maps_update_done();
487 return error;
488}
489
490void __weak arch_enable_nonboot_cpus_begin(void)
491{
492}
493
494void __weak arch_enable_nonboot_cpus_end(void)
495{
496}
497
498void __ref enable_nonboot_cpus(void)
499{
500 int cpu, error;
501
502 /* Allow everyone to use the CPU hotplug again */
503 cpu_maps_update_begin();
504 cpu_hotplug_disabled = 0;
505 if (cpumask_empty(frozen_cpus))
506 goto out;
507
508 printk(KERN_INFO "Enabling non-boot CPUs ...\n");
509
510 arch_enable_nonboot_cpus_begin();
511
512 for_each_cpu(cpu, frozen_cpus) {
513 error = _cpu_up(cpu, 1);
514 if (!error) {
515 printk(KERN_INFO "CPU%d is up\n", cpu);
516 continue;
517 }
518 printk(KERN_WARNING "Error taking CPU%d up: %d\n", cpu, error);
519 }
520
521 arch_enable_nonboot_cpus_end();
522
523 cpumask_clear(frozen_cpus);
524out:
525 cpu_maps_update_done();
526}
527
528static int __init alloc_frozen_cpus(void)
529{
530 if (!alloc_cpumask_var(&frozen_cpus, GFP_KERNEL|__GFP_ZERO))
531 return -ENOMEM;
532 return 0;
533}
534core_initcall(alloc_frozen_cpus);
535
536/*
537 * Prevent regular CPU hotplug from racing with the freezer, by disabling CPU
538 * hotplug when tasks are about to be frozen. Also, don't allow the freezer
539 * to continue until any currently running CPU hotplug operation gets
540 * completed.
541 * To modify the 'cpu_hotplug_disabled' flag, we need to acquire the
542 * 'cpu_add_remove_lock'. And this same lock is also taken by the regular
543 * CPU hotplug path and released only after it is complete. Thus, we
544 * (and hence the freezer) will block here until any currently running CPU
545 * hotplug operation gets completed.
546 */
547void cpu_hotplug_disable_before_freeze(void)
548{
549 cpu_maps_update_begin();
550 cpu_hotplug_disabled = 1;
551 cpu_maps_update_done();
552}
553
554
555/*
556 * When tasks have been thawed, re-enable regular CPU hotplug (which had been
557 * disabled while beginning to freeze tasks).
558 */
559void cpu_hotplug_enable_after_thaw(void)
560{
561 cpu_maps_update_begin();
562 cpu_hotplug_disabled = 0;
563 cpu_maps_update_done();
564}
565
566/*
567 * When callbacks for CPU hotplug notifications are being executed, we must
568 * ensure that the state of the system with respect to the tasks being frozen
569 * or not, as reported by the notification, remains unchanged *throughout the
570 * duration* of the execution of the callbacks.
571 * Hence we need to prevent the freezer from racing with regular CPU hotplug.
572 *
573 * This synchronization is implemented by mutually excluding regular CPU
574 * hotplug and Suspend/Hibernate call paths by hooking onto the Suspend/
575 * Hibernate notifications.
576 */
577static int
578cpu_hotplug_pm_callback(struct notifier_block *nb,
579 unsigned long action, void *ptr)
580{
581 switch (action) {
582
583 case PM_SUSPEND_PREPARE:
584 case PM_HIBERNATION_PREPARE:
585 cpu_hotplug_disable_before_freeze();
586 break;
587
588 case PM_POST_SUSPEND:
589 case PM_POST_HIBERNATION:
590 cpu_hotplug_enable_after_thaw();
591 break;
592
593 default:
594 return NOTIFY_DONE;
595 }
596
597 return NOTIFY_OK;
598}
599
600
601static int __init cpu_hotplug_pm_sync_init(void)
602{
603 pm_notifier(cpu_hotplug_pm_callback, 0);
604 return 0;
605}
606core_initcall(cpu_hotplug_pm_sync_init);
607
608#endif /* CONFIG_PM_SLEEP_SMP */
609
610/**
611 * notify_cpu_starting(cpu) - call the CPU_STARTING notifiers
612 * @cpu: cpu that just started
613 *
614 * This function calls the cpu_chain notifiers with CPU_STARTING.
615 * It must be called by the arch code on the new cpu, before the new cpu
616 * enables interrupts and before the "boot" cpu returns from __cpu_up().
617 */
618void __cpuinit notify_cpu_starting(unsigned int cpu)
619{
620 unsigned long val = CPU_STARTING;
621
622#ifdef CONFIG_PM_SLEEP_SMP
623 if (frozen_cpus != NULL && cpumask_test_cpu(cpu, frozen_cpus))
624 val = CPU_STARTING_FROZEN;
625#endif /* CONFIG_PM_SLEEP_SMP */
626 cpu_notify(val, (void *)(long)cpu);
627}
628
629#endif /* CONFIG_SMP */
630
631/*
632 * cpu_bit_bitmap[] is a special, "compressed" data structure that
633 * represents all NR_CPUS bits binary values of 1<<nr.
634 *
635 * It is used by cpumask_of() to get a constant address to a CPU
636 * mask value that has a single bit set only.
637 */
638
639/* cpu_bit_bitmap[0] is empty - so we can back into it */
640#define MASK_DECLARE_1(x) [x+1][0] = (1UL << (x))
641#define MASK_DECLARE_2(x) MASK_DECLARE_1(x), MASK_DECLARE_1(x+1)
642#define MASK_DECLARE_4(x) MASK_DECLARE_2(x), MASK_DECLARE_2(x+2)
643#define MASK_DECLARE_8(x) MASK_DECLARE_4(x), MASK_DECLARE_4(x+4)
644
645const unsigned long cpu_bit_bitmap[BITS_PER_LONG+1][BITS_TO_LONGS(NR_CPUS)] = {
646
647 MASK_DECLARE_8(0), MASK_DECLARE_8(8),
648 MASK_DECLARE_8(16), MASK_DECLARE_8(24),
649#if BITS_PER_LONG > 32
650 MASK_DECLARE_8(32), MASK_DECLARE_8(40),
651 MASK_DECLARE_8(48), MASK_DECLARE_8(56),
652#endif
653};
654EXPORT_SYMBOL_GPL(cpu_bit_bitmap);
655
656const DECLARE_BITMAP(cpu_all_bits, NR_CPUS) = CPU_BITS_ALL;
657EXPORT_SYMBOL(cpu_all_bits);
658
659#ifdef CONFIG_INIT_ALL_POSSIBLE
660static DECLARE_BITMAP(cpu_possible_bits, CONFIG_NR_CPUS) __read_mostly
661 = CPU_BITS_ALL;
662#else
663static DECLARE_BITMAP(cpu_possible_bits, CONFIG_NR_CPUS) __read_mostly;
664#endif
665const struct cpumask *const cpu_possible_mask = to_cpumask(cpu_possible_bits);
666EXPORT_SYMBOL(cpu_possible_mask);
667
668static DECLARE_BITMAP(cpu_online_bits, CONFIG_NR_CPUS) __read_mostly;
669const struct cpumask *const cpu_online_mask = to_cpumask(cpu_online_bits);
670EXPORT_SYMBOL(cpu_online_mask);
671
672static DECLARE_BITMAP(cpu_present_bits, CONFIG_NR_CPUS) __read_mostly;
673const struct cpumask *const cpu_present_mask = to_cpumask(cpu_present_bits);
674EXPORT_SYMBOL(cpu_present_mask);
675
676static DECLARE_BITMAP(cpu_active_bits, CONFIG_NR_CPUS) __read_mostly;
677const struct cpumask *const cpu_active_mask = to_cpumask(cpu_active_bits);
678EXPORT_SYMBOL(cpu_active_mask);
679
680void set_cpu_possible(unsigned int cpu, bool possible)
681{
682 if (possible)
683 cpumask_set_cpu(cpu, to_cpumask(cpu_possible_bits));
684 else
685 cpumask_clear_cpu(cpu, to_cpumask(cpu_possible_bits));
686}
687
688void set_cpu_present(unsigned int cpu, bool present)
689{
690 if (present)
691 cpumask_set_cpu(cpu, to_cpumask(cpu_present_bits));
692 else
693 cpumask_clear_cpu(cpu, to_cpumask(cpu_present_bits));
694}
695
696void set_cpu_online(unsigned int cpu, bool online)
697{
698 if (online)
699 cpumask_set_cpu(cpu, to_cpumask(cpu_online_bits));
700 else
701 cpumask_clear_cpu(cpu, to_cpumask(cpu_online_bits));
702}
703
704void set_cpu_active(unsigned int cpu, bool active)
705{
706 if (active)
707 cpumask_set_cpu(cpu, to_cpumask(cpu_active_bits));
708 else
709 cpumask_clear_cpu(cpu, to_cpumask(cpu_active_bits));
710}
711
712void init_cpu_present(const struct cpumask *src)
713{
714 cpumask_copy(to_cpumask(cpu_present_bits), src);
715}
716
717void init_cpu_possible(const struct cpumask *src)
718{
719 cpumask_copy(to_cpumask(cpu_possible_bits), src);
720}
721
722void init_cpu_online(const struct cpumask *src)
723{
724 cpumask_copy(to_cpumask(cpu_online_bits), src);
725}