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/kasan.h>
  30#include <linux/mm.h>
  31#include <linux/module.h>
  32#include <linux/nmi.h>
  33#include <linux/init.h>
  34#include <linux/uaccess.h>
  35#include <linux/highmem.h>
  36#include <linux/mmu_context.h>
  37#include <linux/interrupt.h>
  38#include <linux/capability.h>
  39#include <linux/completion.h>
  40#include <linux/kernel_stat.h>
  41#include <linux/debug_locks.h>
  42#include <linux/perf_event.h>
  43#include <linux/security.h>
  44#include <linux/notifier.h>
  45#include <linux/profile.h>
  46#include <linux/freezer.h>
  47#include <linux/vmalloc.h>
  48#include <linux/blkdev.h>
  49#include <linux/delay.h>
  50#include <linux/pid_namespace.h>
  51#include <linux/smp.h>
  52#include <linux/threads.h>
  53#include <linux/timer.h>
  54#include <linux/rcupdate.h>
  55#include <linux/cpu.h>
  56#include <linux/cpuset.h>
  57#include <linux/percpu.h>
  58#include <linux/proc_fs.h>
  59#include <linux/seq_file.h>
  60#include <linux/sysctl.h>
  61#include <linux/syscalls.h>
  62#include <linux/times.h>
  63#include <linux/tsacct_kern.h>
  64#include <linux/kprobes.h>
  65#include <linux/delayacct.h>
  66#include <linux/unistd.h>
  67#include <linux/pagemap.h>
  68#include <linux/hrtimer.h>
  69#include <linux/tick.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/context_tracking.h>
  75#include <linux/compiler.h>
  76#include <linux/frame.h>
  77#include <linux/prefetch.h>
  78#include <linux/mutex.h>
  79
  80#include <asm/switch_to.h>
  81#include <asm/tlb.h>
  82#include <asm/irq_regs.h>
  83#ifdef CONFIG_PARAVIRT
  84#include <asm/paravirt.h>
  85#endif
  86
  87#include "sched.h"
  88#include "../workqueue_internal.h"
  89#include "../smpboot.h"
  90
  91#define CREATE_TRACE_POINTS
  92#include <trace/events/sched.h>
  93
  94DEFINE_MUTEX(sched_domains_mutex);
  95DEFINE_PER_CPU_SHARED_ALIGNED(struct rq, runqueues);
  96
  97static void update_rq_clock_task(struct rq *rq, s64 delta);
  98
  99void update_rq_clock(struct rq *rq)
 100{
 101	s64 delta;
 102
 103	lockdep_assert_held(&rq->lock);
 104
 105	if (rq->clock_skip_update & RQCF_ACT_SKIP)
 106		return;
 107
 108	delta = sched_clock_cpu(cpu_of(rq)) - rq->clock;
 109	if (delta < 0)
 110		return;
 111	rq->clock += delta;
 112	update_rq_clock_task(rq, delta);
 113}
 114
 115/*
 116 * Debugging: various feature bits
 
 
 
 
 117 */
 118
 119#define SCHED_FEAT(name, enabled)	\
 120	(1UL << __SCHED_FEAT_##name) * enabled |
 121
 122const_debug unsigned int sysctl_sched_features =
 123#include "features.h"
 124	0;
 125
 126#undef SCHED_FEAT
 
 127
 128/*
 129 * Number of tasks to iterate in a single balance run.
 130 * Limited because this is done with IRQs disabled.
 131 */
 132const_debug unsigned int sysctl_sched_nr_migrate = 32;
 133
 134/*
 135 * period over which we average the RT time consumption, measured
 136 * in ms.
 137 *
 138 * default: 1s
 139 */
 140const_debug unsigned int sysctl_sched_time_avg = MSEC_PER_SEC;
 141
 142/*
 143 * period over which we measure -rt task cpu usage in us.
 144 * default: 1s
 145 */
 146unsigned int sysctl_sched_rt_period = 1000000;
 147
 148__read_mostly int scheduler_running;
 149
 150/*
 151 * part of the period that we allow rt tasks to run in us.
 152 * default: 0.95s
 153 */
 154int sysctl_sched_rt_runtime = 950000;
 155
 156/* cpus with isolated domains */
 157cpumask_var_t cpu_isolated_map;
 158
 159/*
 160 * this_rq_lock - lock this runqueue and disable interrupts.
 161 */
 162static struct rq *this_rq_lock(void)
 163	__acquires(rq->lock)
 164{
 165	struct rq *rq;
 166
 167	local_irq_disable();
 168	rq = this_rq();
 169	raw_spin_lock(&rq->lock);
 170
 171	return rq;
 172}
 173
 174/*
 175 * __task_rq_lock - lock the rq @p resides on.
 176 */
 177struct rq *__task_rq_lock(struct task_struct *p, struct rq_flags *rf)
 178	__acquires(rq->lock)
 179{
 180	struct rq *rq;
 181
 182	lockdep_assert_held(&p->pi_lock);
 183
 184	for (;;) {
 185		rq = task_rq(p);
 186		raw_spin_lock(&rq->lock);
 187		if (likely(rq == task_rq(p) && !task_on_rq_migrating(p))) {
 188			rf->cookie = lockdep_pin_lock(&rq->lock);
 189			return rq;
 190		}
 191		raw_spin_unlock(&rq->lock);
 192
 193		while (unlikely(task_on_rq_migrating(p)))
 194			cpu_relax();
 195	}
 196}
 197
 198/*
 199 * task_rq_lock - lock p->pi_lock and lock the rq @p resides on.
 200 */
 201struct rq *task_rq_lock(struct task_struct *p, struct rq_flags *rf)
 202	__acquires(p->pi_lock)
 203	__acquires(rq->lock)
 204{
 205	struct rq *rq;
 206
 207	for (;;) {
 208		raw_spin_lock_irqsave(&p->pi_lock, rf->flags);
 209		rq = task_rq(p);
 210		raw_spin_lock(&rq->lock);
 211		/*
 212		 *	move_queued_task()		task_rq_lock()
 213		 *
 214		 *	ACQUIRE (rq->lock)
 215		 *	[S] ->on_rq = MIGRATING		[L] rq = task_rq()
 216		 *	WMB (__set_task_cpu())		ACQUIRE (rq->lock);
 217		 *	[S] ->cpu = new_cpu		[L] task_rq()
 218		 *					[L] ->on_rq
 219		 *	RELEASE (rq->lock)
 220		 *
 221		 * If we observe the old cpu in task_rq_lock, the acquire of
 222		 * the old rq->lock will fully serialize against the stores.
 223		 *
 224		 * If we observe the new cpu in task_rq_lock, the acquire will
 225		 * pair with the WMB to ensure we must then also see migrating.
 226		 */
 227		if (likely(rq == task_rq(p) && !task_on_rq_migrating(p))) {
 228			rf->cookie = lockdep_pin_lock(&rq->lock);
 229			return rq;
 230		}
 231		raw_spin_unlock(&rq->lock);
 232		raw_spin_unlock_irqrestore(&p->pi_lock, rf->flags);
 233
 234		while (unlikely(task_on_rq_migrating(p)))
 235			cpu_relax();
 236	}
 237}
 238
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 239#ifdef CONFIG_SCHED_HRTICK
 240/*
 241 * Use HR-timers to deliver accurate preemption points.
 242 */
 243
 244static void hrtick_clear(struct rq *rq)
 245{
 246	if (hrtimer_active(&rq->hrtick_timer))
 247		hrtimer_cancel(&rq->hrtick_timer);
 248}
 249
 250/*
 251 * High-resolution timer tick.
 252 * Runs from hardirq context with interrupts disabled.
 253 */
 254static enum hrtimer_restart hrtick(struct hrtimer *timer)
 255{
 256	struct rq *rq = container_of(timer, struct rq, hrtick_timer);
 
 257
 258	WARN_ON_ONCE(cpu_of(rq) != smp_processor_id());
 259
 260	raw_spin_lock(&rq->lock);
 261	update_rq_clock(rq);
 262	rq->curr->sched_class->task_tick(rq, rq->curr, 1);
 263	raw_spin_unlock(&rq->lock);
 264
 265	return HRTIMER_NORESTART;
 266}
 267
 268#ifdef CONFIG_SMP
 269
 270static void __hrtick_restart(struct rq *rq)
 271{
 272	struct hrtimer *timer = &rq->hrtick_timer;
 273
 274	hrtimer_start_expires(timer, HRTIMER_MODE_ABS_PINNED);
 275}
 276
 277/*
 278 * called from hardirq (IPI) context
 279 */
 280static void __hrtick_start(void *arg)
 281{
 282	struct rq *rq = arg;
 
 283
 284	raw_spin_lock(&rq->lock);
 285	__hrtick_restart(rq);
 286	rq->hrtick_csd_pending = 0;
 287	raw_spin_unlock(&rq->lock);
 288}
 289
 290/*
 291 * Called to set the hrtick timer state.
 292 *
 293 * called with rq->lock held and irqs disabled
 294 */
 295void hrtick_start(struct rq *rq, u64 delay)
 296{
 297	struct hrtimer *timer = &rq->hrtick_timer;
 298	ktime_t time;
 299	s64 delta;
 300
 301	/*
 302	 * Don't schedule slices shorter than 10000ns, that just
 303	 * doesn't make sense and can cause timer DoS.
 304	 */
 305	delta = max_t(s64, delay, 10000LL);
 306	time = ktime_add_ns(timer->base->get_time(), delta);
 307
 308	hrtimer_set_expires(timer, time);
 309
 310	if (rq == this_rq()) {
 311		__hrtick_restart(rq);
 312	} else if (!rq->hrtick_csd_pending) {
 313		smp_call_function_single_async(cpu_of(rq), &rq->hrtick_csd);
 314		rq->hrtick_csd_pending = 1;
 315	}
 316}
 317
 318#else
 319/*
 320 * Called to set the hrtick timer state.
 321 *
 322 * called with rq->lock held and irqs disabled
 323 */
 324void hrtick_start(struct rq *rq, u64 delay)
 325{
 326	/*
 327	 * Don't schedule slices shorter than 10000ns, that just
 328	 * doesn't make sense. Rely on vruntime for fairness.
 329	 */
 330	delay = max_t(u64, delay, 10000LL);
 331	hrtimer_start(&rq->hrtick_timer, ns_to_ktime(delay),
 332		      HRTIMER_MODE_REL_PINNED);
 333}
 334#endif /* CONFIG_SMP */
 335
 336static void init_rq_hrtick(struct rq *rq)
 337{
 338#ifdef CONFIG_SMP
 339	rq->hrtick_csd_pending = 0;
 340
 341	rq->hrtick_csd.flags = 0;
 342	rq->hrtick_csd.func = __hrtick_start;
 343	rq->hrtick_csd.info = rq;
 344#endif
 345
 346	hrtimer_init(&rq->hrtick_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
 347	rq->hrtick_timer.function = hrtick;
 348}
 349#else	/* CONFIG_SCHED_HRTICK */
 350static inline void hrtick_clear(struct rq *rq)
 351{
 352}
 353
 354static inline void init_rq_hrtick(struct rq *rq)
 355{
 356}
 357#endif	/* CONFIG_SCHED_HRTICK */
 358
 359/*
 360 * cmpxchg based fetch_or, macro so it works for different integer types
 361 */
 362#define fetch_or(ptr, mask)						\
 363	({								\
 364		typeof(ptr) _ptr = (ptr);				\
 365		typeof(mask) _mask = (mask);				\
 366		typeof(*_ptr) _old, _val = *_ptr;			\
 367									\
 368		for (;;) {						\
 369			_old = cmpxchg(_ptr, _val, _val | _mask);	\
 370			if (_old == _val)				\
 371				break;					\
 372			_val = _old;					\
 373		}							\
 374	_old;								\
 375})
 376
 377#if defined(CONFIG_SMP) && defined(TIF_POLLING_NRFLAG)
 378/*
 379 * Atomically set TIF_NEED_RESCHED and test for TIF_POLLING_NRFLAG,
 380 * this avoids any races wrt polling state changes and thereby avoids
 381 * spurious IPIs.
 382 */
 383static bool set_nr_and_not_polling(struct task_struct *p)
 384{
 385	struct thread_info *ti = task_thread_info(p);
 386	return !(fetch_or(&ti->flags, _TIF_NEED_RESCHED) & _TIF_POLLING_NRFLAG);
 387}
 388
 389/*
 390 * Atomically set TIF_NEED_RESCHED if TIF_POLLING_NRFLAG is set.
 391 *
 392 * If this returns true, then the idle task promises to call
 393 * sched_ttwu_pending() and reschedule soon.
 394 */
 395static bool set_nr_if_polling(struct task_struct *p)
 396{
 397	struct thread_info *ti = task_thread_info(p);
 398	typeof(ti->flags) old, val = READ_ONCE(ti->flags);
 399
 400	for (;;) {
 401		if (!(val & _TIF_POLLING_NRFLAG))
 402			return false;
 403		if (val & _TIF_NEED_RESCHED)
 404			return true;
 405		old = cmpxchg(&ti->flags, val, val | _TIF_NEED_RESCHED);
 406		if (old == val)
 407			break;
 408		val = old;
 409	}
 410	return true;
 411}
 412
 413#else
 414static bool set_nr_and_not_polling(struct task_struct *p)
 415{
 416	set_tsk_need_resched(p);
 417	return true;
 418}
 419
 420#ifdef CONFIG_SMP
 421static bool set_nr_if_polling(struct task_struct *p)
 422{
 423	return false;
 424}
 425#endif
 426#endif
 427
 428void wake_q_add(struct wake_q_head *head, struct task_struct *task)
 429{
 430	struct wake_q_node *node = &task->wake_q;
 431
 432	/*
 433	 * Atomically grab the task, if ->wake_q is !nil already it means
 434	 * its already queued (either by us or someone else) and will get the
 435	 * wakeup due to that.
 436	 *
 437	 * This cmpxchg() implies a full barrier, which pairs with the write
 438	 * barrier implied by the wakeup in wake_up_q().
 439	 */
 440	if (cmpxchg(&node->next, NULL, WAKE_Q_TAIL))
 441		return;
 442
 443	get_task_struct(task);
 444
 445	/*
 446	 * The head is context local, there can be no concurrency.
 447	 */
 448	*head->lastp = node;
 449	head->lastp = &node->next;
 450}
 451
 452void wake_up_q(struct wake_q_head *head)
 453{
 454	struct wake_q_node *node = head->first;
 455
 456	while (node != WAKE_Q_TAIL) {
 457		struct task_struct *task;
 458
 459		task = container_of(node, struct task_struct, wake_q);
 460		BUG_ON(!task);
 461		/* task can safely be re-inserted now */
 462		node = node->next;
 463		task->wake_q.next = NULL;
 464
 465		/*
 466		 * wake_up_process() implies a wmb() to pair with the queueing
 467		 * in wake_q_add() so as not to miss wakeups.
 468		 */
 469		wake_up_process(task);
 470		put_task_struct(task);
 471	}
 472}
 473
 474/*
 475 * resched_curr - mark rq's current task 'to be rescheduled now'.
 476 *
 477 * On UP this means the setting of the need_resched flag, on SMP it
 478 * might also involve a cross-CPU call to trigger the scheduler on
 479 * the target CPU.
 480 */
 481void resched_curr(struct rq *rq)
 482{
 483	struct task_struct *curr = rq->curr;
 484	int cpu;
 485
 486	lockdep_assert_held(&rq->lock);
 487
 488	if (test_tsk_need_resched(curr))
 489		return;
 490
 491	cpu = cpu_of(rq);
 492
 493	if (cpu == smp_processor_id()) {
 494		set_tsk_need_resched(curr);
 495		set_preempt_need_resched();
 496		return;
 497	}
 498
 499	if (set_nr_and_not_polling(curr))
 500		smp_send_reschedule(cpu);
 501	else
 502		trace_sched_wake_idle_without_ipi(cpu);
 503}
 504
 505void resched_cpu(int cpu)
 506{
 507	struct rq *rq = cpu_rq(cpu);
 508	unsigned long flags;
 509
 510	if (!raw_spin_trylock_irqsave(&rq->lock, flags))
 511		return;
 512	resched_curr(rq);
 513	raw_spin_unlock_irqrestore(&rq->lock, flags);
 514}
 515
 516#ifdef CONFIG_SMP
 517#ifdef CONFIG_NO_HZ_COMMON
 518/*
 519 * In the semi idle case, use the nearest busy cpu for migrating timers
 520 * from an idle cpu.  This is good for power-savings.
 521 *
 522 * We don't do similar optimization for completely idle system, as
 523 * selecting an idle cpu will add more delays to the timers than intended
 524 * (as that cpu's timer base may not be uptodate wrt jiffies etc).
 525 */
 526int get_nohz_timer_target(void)
 527{
 528	int i, cpu = smp_processor_id();
 529	struct sched_domain *sd;
 530
 531	if (!idle_cpu(cpu) && is_housekeeping_cpu(cpu))
 532		return cpu;
 533
 534	rcu_read_lock();
 535	for_each_domain(cpu, sd) {
 536		for_each_cpu(i, sched_domain_span(sd)) {
 537			if (cpu == i)
 538				continue;
 539
 540			if (!idle_cpu(i) && is_housekeeping_cpu(i)) {
 541				cpu = i;
 542				goto unlock;
 543			}
 544		}
 545	}
 546
 547	if (!is_housekeeping_cpu(cpu))
 548		cpu = housekeeping_any_cpu();
 549unlock:
 550	rcu_read_unlock();
 551	return cpu;
 552}
 
 553/*
 554 * When add_timer_on() enqueues a timer into the timer wheel of an
 555 * idle CPU then this timer might expire before the next timer event
 556 * which is scheduled to wake up that CPU. In case of a completely
 557 * idle system the next event might even be infinite time into the
 558 * future. wake_up_idle_cpu() ensures that the CPU is woken up and
 559 * leaves the inner idle loop so the newly added timer is taken into
 560 * account when the CPU goes back to idle and evaluates the timer
 561 * wheel for the next timer event.
 562 */
 563static void wake_up_idle_cpu(int cpu)
 564{
 565	struct rq *rq = cpu_rq(cpu);
 566
 567	if (cpu == smp_processor_id())
 568		return;
 569
 570	if (set_nr_and_not_polling(rq->idle))
 571		smp_send_reschedule(cpu);
 572	else
 573		trace_sched_wake_idle_without_ipi(cpu);
 574}
 575
 576static bool wake_up_full_nohz_cpu(int cpu)
 577{
 578	/*
 579	 * We just need the target to call irq_exit() and re-evaluate
 580	 * the next tick. The nohz full kick at least implies that.
 581	 * If needed we can still optimize that later with an
 582	 * empty IRQ.
 583	 */
 584	if (cpu_is_offline(cpu))
 585		return true;  /* Don't try to wake offline CPUs. */
 586	if (tick_nohz_full_cpu(cpu)) {
 587		if (cpu != smp_processor_id() ||
 588		    tick_nohz_tick_stopped())
 589			tick_nohz_full_kick_cpu(cpu);
 590		return true;
 591	}
 592
 593	return false;
 594}
 595
 596/*
 597 * Wake up the specified CPU.  If the CPU is going offline, it is the
 598 * caller's responsibility to deal with the lost wakeup, for example,
 599 * by hooking into the CPU_DEAD notifier like timers and hrtimers do.
 600 */
 601void wake_up_nohz_cpu(int cpu)
 602{
 603	if (!wake_up_full_nohz_cpu(cpu))
 604		wake_up_idle_cpu(cpu);
 605}
 606
 607static inline bool got_nohz_idle_kick(void)
 608{
 609	int cpu = smp_processor_id();
 610
 611	if (!test_bit(NOHZ_BALANCE_KICK, nohz_flags(cpu)))
 612		return false;
 613
 614	if (idle_cpu(cpu) && !need_resched())
 615		return true;
 616
 617	/*
 618	 * We can't run Idle Load Balance on this CPU for this time so we
 619	 * cancel it and clear NOHZ_BALANCE_KICK
 620	 */
 621	clear_bit(NOHZ_BALANCE_KICK, nohz_flags(cpu));
 622	return false;
 623}
 624
 625#else /* CONFIG_NO_HZ_COMMON */
 626
 627static inline bool got_nohz_idle_kick(void)
 628{
 629	return false;
 630}
 631
 632#endif /* CONFIG_NO_HZ_COMMON */
 633
 634#ifdef CONFIG_NO_HZ_FULL
 635bool sched_can_stop_tick(struct rq *rq)
 636{
 637	int fifo_nr_running;
 638
 639	/* Deadline tasks, even if single, need the tick */
 640	if (rq->dl.dl_nr_running)
 641		return false;
 642
 643	/*
 644	 * If there are more than one RR tasks, we need the tick to effect the
 645	 * actual RR behaviour.
 646	 */
 647	if (rq->rt.rr_nr_running) {
 648		if (rq->rt.rr_nr_running == 1)
 649			return true;
 650		else
 651			return false;
 652	}
 653
 654	/*
 655	 * If there's no RR tasks, but FIFO tasks, we can skip the tick, no
 656	 * forced preemption between FIFO tasks.
 657	 */
 658	fifo_nr_running = rq->rt.rt_nr_running - rq->rt.rr_nr_running;
 659	if (fifo_nr_running)
 660		return true;
 661
 662	/*
 663	 * If there are no DL,RR/FIFO tasks, there must only be CFS tasks left;
 664	 * if there's more than one we need the tick for involuntary
 665	 * preemption.
 666	 */
 667	if (rq->nr_running > 1)
 668		return false;
 669
 670	return true;
 671}
 672#endif /* CONFIG_NO_HZ_FULL */
 673
 674void sched_avg_update(struct rq *rq)
 675{
 676	s64 period = sched_avg_period();
 677
 678	while ((s64)(rq_clock(rq) - rq->age_stamp) > period) {
 679		/*
 680		 * Inline assembly required to prevent the compiler
 681		 * optimising this loop into a divmod call.
 682		 * See __iter_div_u64_rem() for another example of this.
 683		 */
 684		asm("" : "+rm" (rq->age_stamp));
 685		rq->age_stamp += period;
 686		rq->rt_avg /= 2;
 687	}
 688}
 689
 690#endif /* CONFIG_SMP */
 691
 692#if defined(CONFIG_RT_GROUP_SCHED) || (defined(CONFIG_FAIR_GROUP_SCHED) && \
 693			(defined(CONFIG_SMP) || defined(CONFIG_CFS_BANDWIDTH)))
 694/*
 695 * Iterate task_group tree rooted at *from, calling @down when first entering a
 696 * node and @up when leaving it for the final time.
 697 *
 698 * Caller must hold rcu_lock or sufficient equivalent.
 699 */
 700int walk_tg_tree_from(struct task_group *from,
 701			     tg_visitor down, tg_visitor up, void *data)
 702{
 703	struct task_group *parent, *child;
 704	int ret;
 705
 706	parent = from;
 707
 708down:
 709	ret = (*down)(parent, data);
 710	if (ret)
 711		goto out;
 712	list_for_each_entry_rcu(child, &parent->children, siblings) {
 713		parent = child;
 714		goto down;
 715
 716up:
 717		continue;
 718	}
 719	ret = (*up)(parent, data);
 720	if (ret || parent == from)
 721		goto out;
 722
 723	child = parent;
 724	parent = parent->parent;
 725	if (parent)
 726		goto up;
 727out:
 728	return ret;
 729}
 730
 731int tg_nop(struct task_group *tg, void *data)
 732{
 733	return 0;
 734}
 735#endif
 736
 737static void set_load_weight(struct task_struct *p)
 738{
 739	int prio = p->static_prio - MAX_RT_PRIO;
 740	struct load_weight *load = &p->se.load;
 741
 742	/*
 743	 * SCHED_IDLE tasks get minimal weight:
 744	 */
 745	if (idle_policy(p->policy)) {
 746		load->weight = scale_load(WEIGHT_IDLEPRIO);
 747		load->inv_weight = WMULT_IDLEPRIO;
 748		return;
 749	}
 750
 751	load->weight = scale_load(sched_prio_to_weight[prio]);
 752	load->inv_weight = sched_prio_to_wmult[prio];
 
 
 
 
 
 
 
 
 753}
 754
 755static inline void enqueue_task(struct rq *rq, struct task_struct *p, int flags)
 756{
 757	update_rq_clock(rq);
 
 
 758	if (!(flags & ENQUEUE_RESTORE))
 759		sched_info_queued(rq, p);
 
 760	p->sched_class->enqueue_task(rq, p, flags);
 761}
 762
 763static inline void dequeue_task(struct rq *rq, struct task_struct *p, int flags)
 764{
 765	update_rq_clock(rq);
 
 
 766	if (!(flags & DEQUEUE_SAVE))
 767		sched_info_dequeued(rq, p);
 
 768	p->sched_class->dequeue_task(rq, p, flags);
 769}
 770
 771void activate_task(struct rq *rq, struct task_struct *p, int flags)
 772{
 773	if (task_contributes_to_load(p))
 774		rq->nr_uninterruptible--;
 775
 776	enqueue_task(rq, p, flags);
 777}
 778
 779void deactivate_task(struct rq *rq, struct task_struct *p, int flags)
 780{
 781	if (task_contributes_to_load(p))
 782		rq->nr_uninterruptible++;
 783
 784	dequeue_task(rq, p, flags);
 785}
 786
 787static void update_rq_clock_task(struct rq *rq, s64 delta)
 788{
 789/*
 790 * In theory, the compile should just see 0 here, and optimize out the call
 791 * to sched_rt_avg_update. But I don't trust it...
 792 */
 793#if defined(CONFIG_IRQ_TIME_ACCOUNTING) || defined(CONFIG_PARAVIRT_TIME_ACCOUNTING)
 794	s64 steal = 0, irq_delta = 0;
 795#endif
 796#ifdef CONFIG_IRQ_TIME_ACCOUNTING
 797	irq_delta = irq_time_read(cpu_of(rq)) - rq->prev_irq_time;
 798
 799	/*
 800	 * Since irq_time is only updated on {soft,}irq_exit, we might run into
 801	 * this case when a previous update_rq_clock() happened inside a
 802	 * {soft,}irq region.
 803	 *
 804	 * When this happens, we stop ->clock_task and only update the
 805	 * prev_irq_time stamp to account for the part that fit, so that a next
 806	 * update will consume the rest. This ensures ->clock_task is
 807	 * monotonic.
 808	 *
 809	 * It does however cause some slight miss-attribution of {soft,}irq
 810	 * time, a more accurate solution would be to update the irq_time using
 811	 * the current rq->clock timestamp, except that would require using
 812	 * atomic ops.
 813	 */
 814	if (irq_delta > delta)
 815		irq_delta = delta;
 816
 817	rq->prev_irq_time += irq_delta;
 818	delta -= irq_delta;
 819#endif
 820#ifdef CONFIG_PARAVIRT_TIME_ACCOUNTING
 821	if (static_key_false((&paravirt_steal_rq_enabled))) {
 822		steal = paravirt_steal_clock(cpu_of(rq));
 823		steal -= rq->prev_steal_time_rq;
 824
 825		if (unlikely(steal > delta))
 826			steal = delta;
 827
 828		rq->prev_steal_time_rq += steal;
 829		delta -= steal;
 830	}
 831#endif
 832
 833	rq->clock_task += delta;
 834
 835#if defined(CONFIG_IRQ_TIME_ACCOUNTING) || defined(CONFIG_PARAVIRT_TIME_ACCOUNTING)
 836	if ((irq_delta + steal) && sched_feat(NONTASK_CAPACITY))
 837		sched_rt_avg_update(rq, irq_delta + steal);
 838#endif
 839}
 840
 841void sched_set_stop_task(int cpu, struct task_struct *stop)
 842{
 843	struct sched_param param = { .sched_priority = MAX_RT_PRIO - 1 };
 844	struct task_struct *old_stop = cpu_rq(cpu)->stop;
 845
 846	if (stop) {
 847		/*
 848		 * Make it appear like a SCHED_FIFO task, its something
 849		 * userspace knows about and won't get confused about.
 850		 *
 851		 * Also, it will make PI more or less work without too
 852		 * much confusion -- but then, stop work should not
 853		 * rely on PI working anyway.
 854		 */
 855		sched_setscheduler_nocheck(stop, SCHED_FIFO, &param);
 856
 857		stop->sched_class = &stop_sched_class;
 858	}
 859
 860	cpu_rq(cpu)->stop = stop;
 861
 862	if (old_stop) {
 863		/*
 864		 * Reset it back to a normal scheduling class so that
 865		 * it can die in pieces.
 866		 */
 867		old_stop->sched_class = &rt_sched_class;
 868	}
 869}
 870
 871/*
 872 * __normal_prio - return the priority that is based on the static prio
 873 */
 874static inline int __normal_prio(struct task_struct *p)
 875{
 876	return p->static_prio;
 877}
 878
 879/*
 880 * Calculate the expected normal priority: i.e. priority
 881 * without taking RT-inheritance into account. Might be
 882 * boosted by interactivity modifiers. Changes upon fork,
 883 * setprio syscalls, and whenever the interactivity
 884 * estimator recalculates.
 885 */
 886static inline int normal_prio(struct task_struct *p)
 887{
 888	int prio;
 889
 890	if (task_has_dl_policy(p))
 891		prio = MAX_DL_PRIO-1;
 892	else if (task_has_rt_policy(p))
 893		prio = MAX_RT_PRIO-1 - p->rt_priority;
 894	else
 895		prio = __normal_prio(p);
 896	return prio;
 897}
 898
 899/*
 900 * Calculate the current priority, i.e. the priority
 901 * taken into account by the scheduler. This value might
 902 * be boosted by RT tasks, or might be boosted by
 903 * interactivity modifiers. Will be RT if the task got
 904 * RT-boosted. If not then it returns p->normal_prio.
 905 */
 906static int effective_prio(struct task_struct *p)
 907{
 908	p->normal_prio = normal_prio(p);
 909	/*
 910	 * If we are RT tasks or we were boosted to RT priority,
 911	 * keep the priority unchanged. Otherwise, update priority
 912	 * to the normal priority:
 913	 */
 914	if (!rt_prio(p->prio))
 915		return p->normal_prio;
 916	return p->prio;
 917}
 918
 919/**
 920 * task_curr - is this task currently executing on a CPU?
 921 * @p: the task in question.
 922 *
 923 * Return: 1 if the task is currently executing. 0 otherwise.
 924 */
 925inline int task_curr(const struct task_struct *p)
 926{
 927	return cpu_curr(task_cpu(p)) == p;
 928}
 929
 930/*
 931 * switched_from, switched_to and prio_changed must _NOT_ drop rq->lock,
 932 * use the balance_callback list if you want balancing.
 933 *
 934 * this means any call to check_class_changed() must be followed by a call to
 935 * balance_callback().
 936 */
 937static inline void check_class_changed(struct rq *rq, struct task_struct *p,
 938				       const struct sched_class *prev_class,
 939				       int oldprio)
 940{
 941	if (prev_class != p->sched_class) {
 942		if (prev_class->switched_from)
 943			prev_class->switched_from(rq, p);
 944
 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_curr(rq);
 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 (task_on_rq_queued(rq->curr) && test_tsk_need_resched(rq->curr))
 972		rq_clock_skip_update(rq, true);
 973}
 974
 975#ifdef CONFIG_SMP
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 976/*
 977 * This is how migration works:
 978 *
 979 * 1) we invoke migration_cpu_stop() on the target CPU using
 980 *    stop_one_cpu().
 981 * 2) stopper starts to run (implicitly forcing the migrated thread
 982 *    off the CPU)
 983 * 3) it checks whether the migrated task is still in the wrong runqueue.
 984 * 4) if it's in the wrong runqueue then the migration thread removes
 985 *    it and puts it into the right queue.
 986 * 5) stopper completes and stop_one_cpu() returns and the migration
 987 *    is done.
 988 */
 989
 990/*
 991 * move_queued_task - move a queued task to new rq.
 992 *
 993 * Returns (locked) new rq. Old rq's lock is released.
 994 */
 995static struct rq *move_queued_task(struct rq *rq, struct task_struct *p, int new_cpu)
 
 996{
 997	lockdep_assert_held(&rq->lock);
 998
 999	p->on_rq = TASK_ON_RQ_MIGRATING;
1000	dequeue_task(rq, p, 0);
1001	set_task_cpu(p, new_cpu);
1002	raw_spin_unlock(&rq->lock);
1003
1004	rq = cpu_rq(new_cpu);
1005
1006	raw_spin_lock(&rq->lock);
1007	BUG_ON(task_cpu(p) != new_cpu);
1008	enqueue_task(rq, p, 0);
1009	p->on_rq = TASK_ON_RQ_QUEUED;
1010	check_preempt_curr(rq, p, 0);
1011
1012	return rq;
1013}
1014
1015struct migration_arg {
1016	struct task_struct *task;
1017	int dest_cpu;
1018};
1019
1020/*
1021 * Move (not current) task off this cpu, onto dest cpu. We're doing
1022 * this because either it can't run here any more (set_cpus_allowed()
1023 * away from this CPU, or CPU going down), or because we're
1024 * attempting to rebalance this task on exec (sched_exec).
1025 *
1026 * So we race with normal scheduler movements, but that's OK, as long
1027 * as the task is no longer on this CPU.
1028 */
1029static struct rq *__migrate_task(struct rq *rq, struct task_struct *p, int dest_cpu)
 
1030{
1031	if (unlikely(!cpu_active(dest_cpu)))
1032		return rq;
1033
1034	/* Affinity changed (again). */
1035	if (!cpumask_test_cpu(dest_cpu, tsk_cpus_allowed(p)))
1036		return rq;
1037
1038	rq = move_queued_task(rq, p, dest_cpu);
 
1039
1040	return rq;
1041}
1042
1043/*
1044 * migration_cpu_stop - this will be executed by a highprio stopper thread
1045 * and performs thread migration by bumping thread off CPU then
1046 * 'pushing' onto another runqueue.
1047 */
1048static int migration_cpu_stop(void *data)
1049{
1050	struct migration_arg *arg = data;
1051	struct task_struct *p = arg->task;
1052	struct rq *rq = this_rq();
 
1053
1054	/*
1055	 * The original target cpu might have gone down and we might
1056	 * be on another cpu but it doesn't matter.
1057	 */
1058	local_irq_disable();
1059	/*
1060	 * We need to explicitly wake pending tasks before running
1061	 * __migrate_task() such that we will not miss enforcing cpus_allowed
1062	 * during wakeups, see set_cpus_allowed_ptr()'s TASK_WAKING test.
1063	 */
1064	sched_ttwu_pending();
1065
1066	raw_spin_lock(&p->pi_lock);
1067	raw_spin_lock(&rq->lock);
1068	/*
1069	 * If task_rq(p) != rq, it cannot be migrated here, because we're
1070	 * holding rq->lock, if p->on_rq == 0 it cannot get enqueued because
1071	 * we're holding p->pi_lock.
1072	 */
1073	if (task_rq(p) == rq) {
1074		if (task_on_rq_queued(p))
1075			rq = __migrate_task(rq, p, arg->dest_cpu);
1076		else
1077			p->wake_cpu = arg->dest_cpu;
1078	}
1079	raw_spin_unlock(&rq->lock);
1080	raw_spin_unlock(&p->pi_lock);
1081
1082	local_irq_enable();
1083	return 0;
1084}
1085
1086/*
1087 * sched_class::set_cpus_allowed must do the below, but is not required to
1088 * actually call this function.
1089 */
1090void set_cpus_allowed_common(struct task_struct *p, const struct cpumask *new_mask)
1091{
1092	cpumask_copy(&p->cpus_allowed, new_mask);
1093	p->nr_cpus_allowed = cpumask_weight(new_mask);
1094}
1095
1096void do_set_cpus_allowed(struct task_struct *p, const struct cpumask *new_mask)
1097{
1098	struct rq *rq = task_rq(p);
1099	bool queued, running;
1100
1101	lockdep_assert_held(&p->pi_lock);
1102
1103	queued = task_on_rq_queued(p);
1104	running = task_current(rq, p);
1105
1106	if (queued) {
1107		/*
1108		 * Because __kthread_bind() calls this on blocked tasks without
1109		 * holding rq->lock.
1110		 */
1111		lockdep_assert_held(&rq->lock);
1112		dequeue_task(rq, p, DEQUEUE_SAVE);
1113	}
1114	if (running)
1115		put_prev_task(rq, p);
1116
1117	p->sched_class->set_cpus_allowed(p, new_mask);
1118
1119	if (queued)
1120		enqueue_task(rq, p, ENQUEUE_RESTORE);
1121	if (running)
1122		set_curr_task(rq, p);
1123}
1124
1125/*
1126 * Change a given task's CPU affinity. Migrate the thread to a
1127 * proper CPU and schedule it away if the CPU it's executing on
1128 * is removed from the allowed bitmask.
1129 *
1130 * NOTE: the caller must have a valid reference to the task, the
1131 * task must not exit() & deallocate itself prematurely. The
1132 * call is not atomic; no spinlocks may be held.
1133 */
1134static int __set_cpus_allowed_ptr(struct task_struct *p,
1135				  const struct cpumask *new_mask, bool check)
1136{
1137	const struct cpumask *cpu_valid_mask = cpu_active_mask;
1138	unsigned int dest_cpu;
1139	struct rq_flags rf;
1140	struct rq *rq;
1141	int ret = 0;
1142
1143	rq = task_rq_lock(p, &rf);
 
1144
1145	if (p->flags & PF_KTHREAD) {
1146		/*
1147		 * Kernel threads are allowed on online && !active CPUs
1148		 */
1149		cpu_valid_mask = cpu_online_mask;
1150	}
1151
1152	/*
1153	 * Must re-check here, to close a race against __kthread_bind(),
1154	 * sched_setaffinity() is not guaranteed to observe the flag.
1155	 */
1156	if (check && (p->flags & PF_NO_SETAFFINITY)) {
1157		ret = -EINVAL;
1158		goto out;
1159	}
1160
1161	if (cpumask_equal(&p->cpus_allowed, new_mask))
1162		goto out;
1163
1164	if (!cpumask_intersects(new_mask, cpu_valid_mask)) {
1165		ret = -EINVAL;
1166		goto out;
1167	}
1168
1169	do_set_cpus_allowed(p, new_mask);
1170
1171	if (p->flags & PF_KTHREAD) {
1172		/*
1173		 * For kernel threads that do indeed end up on online &&
1174		 * !active we want to ensure they are strict per-cpu threads.
1175		 */
1176		WARN_ON(cpumask_intersects(new_mask, cpu_online_mask) &&
1177			!cpumask_intersects(new_mask, cpu_active_mask) &&
1178			p->nr_cpus_allowed != 1);
1179	}
1180
1181	/* Can the task run on the task's current CPU? If so, we're done */
1182	if (cpumask_test_cpu(task_cpu(p), new_mask))
1183		goto out;
1184
1185	dest_cpu = cpumask_any_and(cpu_valid_mask, new_mask);
1186	if (task_running(rq, p) || p->state == TASK_WAKING) {
1187		struct migration_arg arg = { p, dest_cpu };
1188		/* Need help from migration thread: drop lock and wait. */
1189		task_rq_unlock(rq, p, &rf);
1190		stop_one_cpu(cpu_of(rq), migration_cpu_stop, &arg);
1191		tlb_migrate_finish(p->mm);
1192		return 0;
1193	} else if (task_on_rq_queued(p)) {
1194		/*
1195		 * OK, since we're going to drop the lock immediately
1196		 * afterwards anyway.
1197		 */
1198		lockdep_unpin_lock(&rq->lock, rf.cookie);
1199		rq = move_queued_task(rq, p, dest_cpu);
1200		lockdep_repin_lock(&rq->lock, rf.cookie);
1201	}
1202out:
1203	task_rq_unlock(rq, p, &rf);
1204
1205	return ret;
1206}
1207
1208int set_cpus_allowed_ptr(struct task_struct *p, const struct cpumask *new_mask)
1209{
1210	return __set_cpus_allowed_ptr(p, new_mask, false);
1211}
1212EXPORT_SYMBOL_GPL(set_cpus_allowed_ptr);
1213
1214void set_task_cpu(struct task_struct *p, unsigned int new_cpu)
1215{
1216#ifdef CONFIG_SCHED_DEBUG
1217	/*
1218	 * We should never call set_task_cpu() on a blocked task,
1219	 * ttwu() will sort out the placement.
1220	 */
1221	WARN_ON_ONCE(p->state != TASK_RUNNING && p->state != TASK_WAKING &&
1222			!p->on_rq);
1223
1224	/*
1225	 * Migrating fair class task must have p->on_rq = TASK_ON_RQ_MIGRATING,
1226	 * because schedstat_wait_{start,end} rebase migrating task's wait_start
1227	 * time relying on p->on_rq.
1228	 */
1229	WARN_ON_ONCE(p->state == TASK_RUNNING &&
1230		     p->sched_class == &fair_sched_class &&
1231		     (p->on_rq && !task_on_rq_migrating(p)));
1232
1233#ifdef CONFIG_LOCKDEP
1234	/*
1235	 * The caller should hold either p->pi_lock or rq->lock, when changing
1236	 * a task's CPU. ->pi_lock for waking tasks, rq->lock for runnable tasks.
1237	 *
1238	 * sched_move_task() holds both and thus holding either pins the cgroup,
1239	 * see task_group().
1240	 *
1241	 * Furthermore, all task_rq users should acquire both locks, see
1242	 * task_rq_lock().
1243	 */
1244	WARN_ON_ONCE(debug_locks && !(lockdep_is_held(&p->pi_lock) ||
1245				      lockdep_is_held(&task_rq(p)->lock)));
1246#endif
 
 
 
 
1247#endif
1248
1249	trace_sched_migrate_task(p, new_cpu);
1250
1251	if (task_cpu(p) != new_cpu) {
1252		if (p->sched_class->migrate_task_rq)
1253			p->sched_class->migrate_task_rq(p);
1254		p->se.nr_migrations++;
1255		perf_event_task_migrate(p);
1256	}
1257
1258	__set_task_cpu(p, new_cpu);
1259}
1260
1261static void __migrate_swap_task(struct task_struct *p, int cpu)
1262{
1263	if (task_on_rq_queued(p)) {
1264		struct rq *src_rq, *dst_rq;
 
1265
1266		src_rq = task_rq(p);
1267		dst_rq = cpu_rq(cpu);
1268
 
 
 
1269		p->on_rq = TASK_ON_RQ_MIGRATING;
1270		deactivate_task(src_rq, p, 0);
1271		set_task_cpu(p, cpu);
1272		activate_task(dst_rq, p, 0);
1273		p->on_rq = TASK_ON_RQ_QUEUED;
1274		check_preempt_curr(dst_rq, p, 0);
 
 
 
 
1275	} else {
1276		/*
1277		 * Task isn't running anymore; make it appear like we migrated
1278		 * it before it went to sleep. This means on wakeup we make the
1279		 * previous cpu our target instead of where it really is.
1280		 */
1281		p->wake_cpu = cpu;
1282	}
1283}
1284
1285struct migration_swap_arg {
1286	struct task_struct *src_task, *dst_task;
1287	int src_cpu, dst_cpu;
1288};
1289
1290static int migrate_swap_stop(void *data)
1291{
1292	struct migration_swap_arg *arg = data;
1293	struct rq *src_rq, *dst_rq;
1294	int ret = -EAGAIN;
1295
1296	if (!cpu_active(arg->src_cpu) || !cpu_active(arg->dst_cpu))
1297		return -EAGAIN;
1298
1299	src_rq = cpu_rq(arg->src_cpu);
1300	dst_rq = cpu_rq(arg->dst_cpu);
1301
1302	double_raw_lock(&arg->src_task->pi_lock,
1303			&arg->dst_task->pi_lock);
1304	double_rq_lock(src_rq, dst_rq);
1305
1306	if (task_cpu(arg->dst_task) != arg->dst_cpu)
1307		goto unlock;
1308
1309	if (task_cpu(arg->src_task) != arg->src_cpu)
1310		goto unlock;
1311
1312	if (!cpumask_test_cpu(arg->dst_cpu, tsk_cpus_allowed(arg->src_task)))
1313		goto unlock;
1314
1315	if (!cpumask_test_cpu(arg->src_cpu, tsk_cpus_allowed(arg->dst_task)))
1316		goto unlock;
1317
1318	__migrate_swap_task(arg->src_task, arg->dst_cpu);
1319	__migrate_swap_task(arg->dst_task, arg->src_cpu);
1320
1321	ret = 0;
1322
1323unlock:
1324	double_rq_unlock(src_rq, dst_rq);
1325	raw_spin_unlock(&arg->dst_task->pi_lock);
1326	raw_spin_unlock(&arg->src_task->pi_lock);
1327
1328	return ret;
1329}
1330
1331/*
1332 * Cross migrate two tasks
1333 */
1334int migrate_swap(struct task_struct *cur, struct task_struct *p)
1335{
1336	struct migration_swap_arg arg;
1337	int ret = -EINVAL;
1338
1339	arg = (struct migration_swap_arg){
1340		.src_task = cur,
1341		.src_cpu = task_cpu(cur),
1342		.dst_task = p,
1343		.dst_cpu = task_cpu(p),
1344	};
1345
1346	if (arg.src_cpu == arg.dst_cpu)
1347		goto out;
1348
1349	/*
1350	 * These three tests are all lockless; this is OK since all of them
1351	 * will be re-checked with proper locks held further down the line.
1352	 */
1353	if (!cpu_active(arg.src_cpu) || !cpu_active(arg.dst_cpu))
1354		goto out;
1355
1356	if (!cpumask_test_cpu(arg.dst_cpu, tsk_cpus_allowed(arg.src_task)))
1357		goto out;
1358
1359	if (!cpumask_test_cpu(arg.src_cpu, tsk_cpus_allowed(arg.dst_task)))
1360		goto out;
1361
1362	trace_sched_swap_numa(cur, arg.src_cpu, p, arg.dst_cpu);
1363	ret = stop_two_cpus(arg.dst_cpu, arg.src_cpu, migrate_swap_stop, &arg);
1364
1365out:
1366	return ret;
1367}
1368
1369/*
1370 * wait_task_inactive - wait for a thread to unschedule.
1371 *
1372 * If @match_state is nonzero, it's the @p->state value just checked and
1373 * not expected to change.  If it changes, i.e. @p might have woken up,
1374 * then return zero.  When we succeed in waiting for @p to be off its CPU,
1375 * we return a positive number (its total switch count).  If a second call
1376 * a short while later returns the same number, the caller can be sure that
1377 * @p has remained unscheduled the whole time.
1378 *
1379 * The caller must ensure that the task *will* unschedule sometime soon,
1380 * else this function might spin for a *long* time. This function can't
1381 * be called with interrupts off, or it may introduce deadlock with
1382 * smp_call_function() if an IPI is sent by the same process we are
1383 * waiting to become inactive.
1384 */
1385unsigned long wait_task_inactive(struct task_struct *p, long match_state)
1386{
1387	int running, queued;
1388	struct rq_flags rf;
1389	unsigned long ncsw;
1390	struct rq *rq;
1391
1392	for (;;) {
1393		/*
1394		 * We do the initial early heuristics without holding
1395		 * any task-queue locks at all. We'll only try to get
1396		 * the runqueue lock when things look like they will
1397		 * work out!
1398		 */
1399		rq = task_rq(p);
1400
1401		/*
1402		 * If the task is actively running on another CPU
1403		 * still, just relax and busy-wait without holding
1404		 * any locks.
1405		 *
1406		 * NOTE! Since we don't hold any locks, it's not
1407		 * even sure that "rq" stays as the right runqueue!
1408		 * But we don't care, since "task_running()" will
1409		 * return false if the runqueue has changed and p
1410		 * is actually now running somewhere else!
1411		 */
1412		while (task_running(rq, p)) {
1413			if (match_state && unlikely(p->state != match_state))
1414				return 0;
1415			cpu_relax();
1416		}
1417
1418		/*
1419		 * Ok, time to look more closely! We need the rq
1420		 * lock now, to be *sure*. If we're wrong, we'll
1421		 * just go back and repeat.
1422		 */
1423		rq = task_rq_lock(p, &rf);
1424		trace_sched_wait_task(p);
1425		running = task_running(rq, p);
1426		queued = task_on_rq_queued(p);
1427		ncsw = 0;
1428		if (!match_state || p->state == match_state)
1429			ncsw = p->nvcsw | LONG_MIN; /* sets MSB */
1430		task_rq_unlock(rq, p, &rf);
1431
1432		/*
1433		 * If it changed from the expected state, bail out now.
1434		 */
1435		if (unlikely(!ncsw))
1436			break;
1437
1438		/*
1439		 * Was it really running after all now that we
1440		 * checked with the proper locks actually held?
1441		 *
1442		 * Oops. Go back and try again..
1443		 */
1444		if (unlikely(running)) {
1445			cpu_relax();
1446			continue;
1447		}
1448
1449		/*
1450		 * It's not enough that it's not actively running,
1451		 * it must be off the runqueue _entirely_, and not
1452		 * preempted!
1453		 *
1454		 * So if it was still runnable (but just not actively
1455		 * running right now), it's preempted, and we should
1456		 * yield - it could be a while.
1457		 */
1458		if (unlikely(queued)) {
1459			ktime_t to = NSEC_PER_SEC / HZ;
1460
1461			set_current_state(TASK_UNINTERRUPTIBLE);
1462			schedule_hrtimeout(&to, HRTIMER_MODE_REL);
1463			continue;
1464		}
1465
1466		/*
1467		 * Ahh, all good. It wasn't running, and it wasn't
1468		 * runnable, which means that it will never become
1469		 * running in the future either. We're all done!
1470		 */
1471		break;
1472	}
1473
1474	return ncsw;
1475}
1476
1477/***
1478 * kick_process - kick a running thread to enter/exit the kernel
1479 * @p: the to-be-kicked thread
1480 *
1481 * Cause a process which is running on another CPU to enter
1482 * kernel-mode, without any delay. (to get signals handled.)
1483 *
1484 * NOTE: this function doesn't have to take the runqueue lock,
1485 * because all it wants to ensure is that the remote task enters
1486 * the kernel. If the IPI races and the task has been migrated
1487 * to another CPU then no harm is done and the purpose has been
1488 * achieved as well.
1489 */
1490void kick_process(struct task_struct *p)
1491{
1492	int cpu;
1493
1494	preempt_disable();
1495	cpu = task_cpu(p);
1496	if ((cpu != smp_processor_id()) && task_curr(p))
1497		smp_send_reschedule(cpu);
1498	preempt_enable();
1499}
1500EXPORT_SYMBOL_GPL(kick_process);
1501
1502/*
1503 * ->cpus_allowed is protected by both rq->lock and p->pi_lock
1504 *
1505 * A few notes on cpu_active vs cpu_online:
1506 *
1507 *  - cpu_active must be a subset of cpu_online
1508 *
1509 *  - on cpu-up we allow per-cpu kthreads on the online && !active cpu,
1510 *    see __set_cpus_allowed_ptr(). At this point the newly online
1511 *    cpu isn't yet part of the sched domains, and balancing will not
1512 *    see it.
1513 *
1514 *  - on cpu-down we clear cpu_active() to mask the sched domains and
1515 *    avoid the load balancer to place new tasks on the to be removed
1516 *    cpu. Existing tasks will remain running there and will be taken
1517 *    off.
1518 *
1519 * This means that fallback selection must not select !active CPUs.
1520 * And can assume that any active CPU must be online. Conversely
1521 * select_task_rq() below may allow selection of !active CPUs in order
1522 * to satisfy the above rules.
1523 */
1524static int select_fallback_rq(int cpu, struct task_struct *p)
1525{
1526	int nid = cpu_to_node(cpu);
1527	const struct cpumask *nodemask = NULL;
1528	enum { cpuset, possible, fail } state = cpuset;
1529	int dest_cpu;
1530
1531	/*
1532	 * If the node that the cpu is on has been offlined, cpu_to_node()
1533	 * will return -1. There is no cpu on the node, and we should
1534	 * select the cpu on the other node.
1535	 */
1536	if (nid != -1) {
1537		nodemask = cpumask_of_node(nid);
1538
1539		/* Look for allowed, online CPU in same node. */
1540		for_each_cpu(dest_cpu, nodemask) {
1541			if (!cpu_active(dest_cpu))
1542				continue;
1543			if (cpumask_test_cpu(dest_cpu, tsk_cpus_allowed(p)))
1544				return dest_cpu;
1545		}
1546	}
1547
1548	for (;;) {
1549		/* Any allowed, online CPU? */
1550		for_each_cpu(dest_cpu, tsk_cpus_allowed(p)) {
1551			if (!(p->flags & PF_KTHREAD) && !cpu_active(dest_cpu))
1552				continue;
1553			if (!cpu_online(dest_cpu))
1554				continue;
 
1555			goto out;
1556		}
1557
1558		/* No more Mr. Nice Guy. */
1559		switch (state) {
1560		case cpuset:
1561			if (IS_ENABLED(CONFIG_CPUSETS)) {
1562				cpuset_cpus_allowed_fallback(p);
1563				state = possible;
1564				break;
1565			}
1566			/* fall-through */
1567		case possible:
1568			do_set_cpus_allowed(p, cpu_possible_mask);
1569			state = fail;
1570			break;
1571
1572		case fail:
1573			BUG();
1574			break;
1575		}
1576	}
1577
1578out:
1579	if (state != cpuset) {
1580		/*
1581		 * Don't tell them about moving exiting tasks or
1582		 * kernel threads (both mm NULL), since they never
1583		 * leave kernel.
1584		 */
1585		if (p->mm && printk_ratelimit()) {
1586			printk_deferred("process %d (%s) no longer affine to cpu%d\n",
1587					task_pid_nr(p), p->comm, cpu);
1588		}
1589	}
1590
1591	return dest_cpu;
1592}
1593
1594/*
1595 * The caller (fork, wakeup) owns p->pi_lock, ->cpus_allowed is stable.
1596 */
1597static inline
1598int select_task_rq(struct task_struct *p, int cpu, int sd_flags, int wake_flags)
1599{
1600	lockdep_assert_held(&p->pi_lock);
1601
1602	if (tsk_nr_cpus_allowed(p) > 1)
1603		cpu = p->sched_class->select_task_rq(p, cpu, sd_flags, wake_flags);
1604	else
1605		cpu = cpumask_any(tsk_cpus_allowed(p));
1606
1607	/*
1608	 * In order not to call set_task_cpu() on a blocking task we need
1609	 * to rely on ttwu() to place the task on a valid ->cpus_allowed
1610	 * cpu.
1611	 *
1612	 * Since this is common to all placement strategies, this lives here.
1613	 *
1614	 * [ this allows ->select_task() to simply return task_cpu(p) and
1615	 *   not worry about this generic constraint ]
1616	 */
1617	if (unlikely(!cpumask_test_cpu(cpu, tsk_cpus_allowed(p)) ||
1618		     !cpu_online(cpu)))
1619		cpu = select_fallback_rq(task_cpu(p), p);
1620
1621	return cpu;
1622}
1623
1624static void update_avg(u64 *avg, u64 sample)
1625{
1626	s64 diff = sample - *avg;
1627	*avg += diff >> 3;
1628}
1629
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1630#else
1631
1632static inline int __set_cpus_allowed_ptr(struct task_struct *p,
1633					 const struct cpumask *new_mask, bool check)
1634{
1635	return set_cpus_allowed_ptr(p, new_mask);
1636}
1637
1638#endif /* CONFIG_SMP */
1639
1640static void
1641ttwu_stat(struct task_struct *p, int cpu, int wake_flags)
1642{
1643	struct rq *rq;
1644
1645	if (!schedstat_enabled())
1646		return;
1647
1648	rq = this_rq();
1649
1650#ifdef CONFIG_SMP
1651	if (cpu == rq->cpu) {
1652		schedstat_inc(rq->ttwu_local);
1653		schedstat_inc(p->se.statistics.nr_wakeups_local);
1654	} else {
1655		struct sched_domain *sd;
1656
1657		schedstat_inc(p->se.statistics.nr_wakeups_remote);
1658		rcu_read_lock();
1659		for_each_domain(rq->cpu, sd) {
1660			if (cpumask_test_cpu(cpu, sched_domain_span(sd))) {
1661				schedstat_inc(sd->ttwu_wake_remote);
1662				break;
1663			}
1664		}
1665		rcu_read_unlock();
1666	}
1667
1668	if (wake_flags & WF_MIGRATED)
1669		schedstat_inc(p->se.statistics.nr_wakeups_migrate);
1670#endif /* CONFIG_SMP */
1671
1672	schedstat_inc(rq->ttwu_count);
1673	schedstat_inc(p->se.statistics.nr_wakeups);
1674
1675	if (wake_flags & WF_SYNC)
1676		schedstat_inc(p->se.statistics.nr_wakeups_sync);
1677}
1678
1679static inline void ttwu_activate(struct rq *rq, struct task_struct *p, int en_flags)
1680{
1681	activate_task(rq, p, en_flags);
1682	p->on_rq = TASK_ON_RQ_QUEUED;
1683
1684	/* if a worker is waking up, notify workqueue */
1685	if (p->flags & PF_WQ_WORKER)
1686		wq_worker_waking_up(p, cpu_of(rq));
1687}
1688
1689/*
1690 * Mark the task runnable and perform wakeup-preemption.
1691 */
1692static void ttwu_do_wakeup(struct rq *rq, struct task_struct *p, int wake_flags,
1693			   struct pin_cookie cookie)
1694{
1695	check_preempt_curr(rq, p, wake_flags);
1696	p->state = TASK_RUNNING;
1697	trace_sched_wakeup(p);
1698
1699#ifdef CONFIG_SMP
1700	if (p->sched_class->task_woken) {
1701		/*
1702		 * Our task @p is fully woken up and running; so its safe to
1703		 * drop the rq->lock, hereafter rq is only used for statistics.
1704		 */
1705		lockdep_unpin_lock(&rq->lock, cookie);
1706		p->sched_class->task_woken(rq, p);
1707		lockdep_repin_lock(&rq->lock, cookie);
1708	}
1709
1710	if (rq->idle_stamp) {
1711		u64 delta = rq_clock(rq) - rq->idle_stamp;
1712		u64 max = 2*rq->max_idle_balance_cost;
1713
1714		update_avg(&rq->avg_idle, delta);
1715
1716		if (rq->avg_idle > max)
1717			rq->avg_idle = max;
1718
1719		rq->idle_stamp = 0;
1720	}
1721#endif
1722}
1723
1724static void
1725ttwu_do_activate(struct rq *rq, struct task_struct *p, int wake_flags,
1726		 struct pin_cookie cookie)
1727{
1728	int en_flags = ENQUEUE_WAKEUP;
1729
1730	lockdep_assert_held(&rq->lock);
1731
1732#ifdef CONFIG_SMP
1733	if (p->sched_contributes_to_load)
1734		rq->nr_uninterruptible--;
1735
1736	if (wake_flags & WF_MIGRATED)
1737		en_flags |= ENQUEUE_MIGRATED;
1738#endif
1739
1740	ttwu_activate(rq, p, en_flags);
1741	ttwu_do_wakeup(rq, p, wake_flags, cookie);
1742}
1743
1744/*
1745 * Called in case the task @p isn't fully descheduled from its runqueue,
1746 * in this case we must do a remote wakeup. Its a 'light' wakeup though,
1747 * since all we need to do is flip p->state to TASK_RUNNING, since
1748 * the task is still ->on_rq.
1749 */
1750static int ttwu_remote(struct task_struct *p, int wake_flags)
1751{
1752	struct rq_flags rf;
1753	struct rq *rq;
1754	int ret = 0;
1755
1756	rq = __task_rq_lock(p, &rf);
1757	if (task_on_rq_queued(p)) {
1758		/* check_preempt_curr() may use rq clock */
1759		update_rq_clock(rq);
1760		ttwu_do_wakeup(rq, p, wake_flags, rf.cookie);
1761		ret = 1;
1762	}
1763	__task_rq_unlock(rq, &rf);
1764
1765	return ret;
1766}
1767
1768#ifdef CONFIG_SMP
1769void sched_ttwu_pending(void)
1770{
1771	struct rq *rq = this_rq();
1772	struct llist_node *llist = llist_del_all(&rq->wake_list);
1773	struct pin_cookie cookie;
1774	struct task_struct *p;
1775	unsigned long flags;
1776
1777	if (!llist)
1778		return;
1779
1780	raw_spin_lock_irqsave(&rq->lock, flags);
1781	cookie = lockdep_pin_lock(&rq->lock);
1782
1783	while (llist) {
1784		int wake_flags = 0;
1785
1786		p = llist_entry(llist, struct task_struct, wake_entry);
1787		llist = llist_next(llist);
1788
1789		if (p->sched_remote_wakeup)
1790			wake_flags = WF_MIGRATED;
1791
1792		ttwu_do_activate(rq, p, wake_flags, cookie);
1793	}
1794
1795	lockdep_unpin_lock(&rq->lock, cookie);
1796	raw_spin_unlock_irqrestore(&rq->lock, flags);
1797}
1798
1799void scheduler_ipi(void)
1800{
1801	/*
1802	 * Fold TIF_NEED_RESCHED into the preempt_count; anybody setting
1803	 * TIF_NEED_RESCHED remotely (for the first time) will also send
1804	 * this IPI.
1805	 */
1806	preempt_fold_need_resched();
1807
1808	if (llist_empty(&this_rq()->wake_list) && !got_nohz_idle_kick())
1809		return;
1810
1811	/*
1812	 * Not all reschedule IPI handlers call irq_enter/irq_exit, since
1813	 * traditionally all their work was done from the interrupt return
1814	 * path. Now that we actually do some work, we need to make sure
1815	 * we do call them.
1816	 *
1817	 * Some archs already do call them, luckily irq_enter/exit nest
1818	 * properly.
1819	 *
1820	 * Arguably we should visit all archs and update all handlers,
1821	 * however a fair share of IPIs are still resched only so this would
1822	 * somewhat pessimize the simple resched case.
1823	 */
1824	irq_enter();
1825	sched_ttwu_pending();
1826
1827	/*
1828	 * Check if someone kicked us for doing the nohz idle load balance.
1829	 */
1830	if (unlikely(got_nohz_idle_kick())) {
1831		this_rq()->idle_balance = 1;
1832		raise_softirq_irqoff(SCHED_SOFTIRQ);
1833	}
1834	irq_exit();
1835}
1836
1837static void ttwu_queue_remote(struct task_struct *p, int cpu, int wake_flags)
1838{
1839	struct rq *rq = cpu_rq(cpu);
1840
1841	p->sched_remote_wakeup = !!(wake_flags & WF_MIGRATED);
1842
1843	if (llist_add(&p->wake_entry, &cpu_rq(cpu)->wake_list)) {
1844		if (!set_nr_if_polling(rq->idle))
1845			smp_send_reschedule(cpu);
1846		else
1847			trace_sched_wake_idle_without_ipi(cpu);
1848	}
1849}
1850
1851void wake_up_if_idle(int cpu)
1852{
1853	struct rq *rq = cpu_rq(cpu);
1854	unsigned long flags;
1855
1856	rcu_read_lock();
1857
1858	if (!is_idle_task(rcu_dereference(rq->curr)))
1859		goto out;
1860
1861	if (set_nr_if_polling(rq->idle)) {
1862		trace_sched_wake_idle_without_ipi(cpu);
1863	} else {
1864		raw_spin_lock_irqsave(&rq->lock, flags);
1865		if (is_idle_task(rq->curr))
1866			smp_send_reschedule(cpu);
1867		/* Else cpu is not in idle, do nothing here */
1868		raw_spin_unlock_irqrestore(&rq->lock, flags);
1869	}
1870
1871out:
1872	rcu_read_unlock();
1873}
1874
1875bool cpus_share_cache(int this_cpu, int that_cpu)
1876{
1877	return per_cpu(sd_llc_id, this_cpu) == per_cpu(sd_llc_id, that_cpu);
1878}
1879#endif /* CONFIG_SMP */
1880
1881static void ttwu_queue(struct task_struct *p, int cpu, int wake_flags)
1882{
1883	struct rq *rq = cpu_rq(cpu);
1884	struct pin_cookie cookie;
1885
1886#if defined(CONFIG_SMP)
1887	if (sched_feat(TTWU_QUEUE) && !cpus_share_cache(smp_processor_id(), cpu)) {
1888		sched_clock_cpu(cpu); /* sync clocks x-cpu */
1889		ttwu_queue_remote(p, cpu, wake_flags);
1890		return;
1891	}
1892#endif
1893
1894	raw_spin_lock(&rq->lock);
1895	cookie = lockdep_pin_lock(&rq->lock);
1896	ttwu_do_activate(rq, p, wake_flags, cookie);
1897	lockdep_unpin_lock(&rq->lock, cookie);
1898	raw_spin_unlock(&rq->lock);
1899}
1900
1901/*
1902 * Notes on Program-Order guarantees on SMP systems.
1903 *
1904 *  MIGRATION
1905 *
1906 * The basic program-order guarantee on SMP systems is that when a task [t]
1907 * migrates, all its activity on its old cpu [c0] happens-before any subsequent
1908 * execution on its new cpu [c1].
1909 *
1910 * For migration (of runnable tasks) this is provided by the following means:
1911 *
1912 *  A) UNLOCK of the rq(c0)->lock scheduling out task t
1913 *  B) migration for t is required to synchronize *both* rq(c0)->lock and
1914 *     rq(c1)->lock (if not at the same time, then in that order).
1915 *  C) LOCK of the rq(c1)->lock scheduling in task
1916 *
1917 * Transitivity guarantees that B happens after A and C after B.
1918 * Note: we only require RCpc transitivity.
1919 * Note: the cpu doing B need not be c0 or c1
1920 *
1921 * Example:
1922 *
1923 *   CPU0            CPU1            CPU2
1924 *
1925 *   LOCK rq(0)->lock
1926 *   sched-out X
1927 *   sched-in Y
1928 *   UNLOCK rq(0)->lock
1929 *
1930 *                                   LOCK rq(0)->lock // orders against CPU0
1931 *                                   dequeue X
1932 *                                   UNLOCK rq(0)->lock
1933 *
1934 *                                   LOCK rq(1)->lock
1935 *                                   enqueue X
1936 *                                   UNLOCK rq(1)->lock
1937 *
1938 *                   LOCK rq(1)->lock // orders against CPU2
1939 *                   sched-out Z
1940 *                   sched-in X
1941 *                   UNLOCK rq(1)->lock
1942 *
1943 *
1944 *  BLOCKING -- aka. SLEEP + WAKEUP
1945 *
1946 * For blocking we (obviously) need to provide the same guarantee as for
1947 * migration. However the means are completely different as there is no lock
1948 * chain to provide order. Instead we do:
1949 *
1950 *   1) smp_store_release(X->on_cpu, 0)
1951 *   2) smp_cond_load_acquire(!X->on_cpu)
1952 *
1953 * Example:
1954 *
1955 *   CPU0 (schedule)  CPU1 (try_to_wake_up) CPU2 (schedule)
1956 *
1957 *   LOCK rq(0)->lock LOCK X->pi_lock
1958 *   dequeue X
1959 *   sched-out X
1960 *   smp_store_release(X->on_cpu, 0);
1961 *
1962 *                    smp_cond_load_acquire(&X->on_cpu, !VAL);
1963 *                    X->state = WAKING
1964 *                    set_task_cpu(X,2)
1965 *
1966 *                    LOCK rq(2)->lock
1967 *                    enqueue X
1968 *                    X->state = RUNNING
1969 *                    UNLOCK rq(2)->lock
1970 *
1971 *                                          LOCK rq(2)->lock // orders against CPU1
1972 *                                          sched-out Z
1973 *                                          sched-in X
1974 *                                          UNLOCK rq(2)->lock
1975 *
1976 *                    UNLOCK X->pi_lock
1977 *   UNLOCK rq(0)->lock
1978 *
1979 *
1980 * However; for wakeups there is a second guarantee we must provide, namely we
1981 * must observe the state that lead to our wakeup. That is, not only must our
1982 * task observe its own prior state, it must also observe the stores prior to
1983 * its wakeup.
1984 *
1985 * This means that any means of doing remote wakeups must order the CPU doing
1986 * the wakeup against the CPU the task is going to end up running on. This,
1987 * however, is already required for the regular Program-Order guarantee above,
1988 * since the waking CPU is the one issueing the ACQUIRE (smp_cond_load_acquire).
1989 *
1990 */
1991
1992/**
1993 * try_to_wake_up - wake up a thread
1994 * @p: the thread to be awakened
1995 * @state: the mask of task states that can be woken
1996 * @wake_flags: wake modifier flags (WF_*)
1997 *
1998 * If (@state & @p->state) @p->state = TASK_RUNNING.
1999 *
2000 * If the task was not queued/runnable, also place it back on a runqueue.
2001 *
2002 * Atomic against schedule() which would dequeue a task, also see
2003 * set_current_state().
2004 *
2005 * Return: %true if @p->state changes (an actual wakeup was done),
2006 *	   %false otherwise.
2007 */
2008static int
2009try_to_wake_up(struct task_struct *p, unsigned int state, int wake_flags)
2010{
2011	unsigned long flags;
2012	int cpu, success = 0;
2013
2014	/*
2015	 * If we are going to wake up a thread waiting for CONDITION we
2016	 * need to ensure that CONDITION=1 done by the caller can not be
2017	 * reordered with p->state check below. This pairs with mb() in
2018	 * set_current_state() the waiting thread does.
2019	 */
2020	smp_mb__before_spinlock();
2021	raw_spin_lock_irqsave(&p->pi_lock, flags);
 
2022	if (!(p->state & state))
2023		goto out;
2024
2025	trace_sched_waking(p);
2026
2027	success = 1; /* we're going to change ->state */
 
2028	cpu = task_cpu(p);
2029
2030	/*
2031	 * Ensure we load p->on_rq _after_ p->state, otherwise it would
2032	 * be possible to, falsely, observe p->on_rq == 0 and get stuck
2033	 * in smp_cond_load_acquire() below.
2034	 *
2035	 * sched_ttwu_pending()                 try_to_wake_up()
2036	 *   [S] p->on_rq = 1;                  [L] P->state
2037	 *       UNLOCK rq->lock  -----.
2038	 *                              \
2039	 *				 +---   RMB
2040	 * schedule()                   /
2041	 *       LOCK rq->lock    -----'
2042	 *       UNLOCK rq->lock
2043	 *
2044	 * [task p]
2045	 *   [S] p->state = UNINTERRUPTIBLE     [L] p->on_rq
2046	 *
2047	 * Pairs with the UNLOCK+LOCK on rq->lock from the
2048	 * last wakeup of our task and the schedule that got our task
2049	 * current.
2050	 */
2051	smp_rmb();
2052	if (p->on_rq && ttwu_remote(p, wake_flags))
2053		goto stat;
2054
2055#ifdef CONFIG_SMP
2056	/*
2057	 * Ensure we load p->on_cpu _after_ p->on_rq, otherwise it would be
2058	 * possible to, falsely, observe p->on_cpu == 0.
2059	 *
2060	 * One must be running (->on_cpu == 1) in order to remove oneself
2061	 * from the runqueue.
2062	 *
2063	 *  [S] ->on_cpu = 1;	[L] ->on_rq
2064	 *      UNLOCK rq->lock
2065	 *			RMB
2066	 *      LOCK   rq->lock
2067	 *  [S] ->on_rq = 0;    [L] ->on_cpu
2068	 *
2069	 * Pairs with the full barrier implied in the UNLOCK+LOCK on rq->lock
2070	 * from the consecutive calls to schedule(); the first switching to our
2071	 * task, the second putting it to sleep.
2072	 */
2073	smp_rmb();
2074
2075	/*
2076	 * If the owning (remote) cpu is still in the middle of schedule() with
2077	 * this task as prev, wait until its done referencing the task.
2078	 *
2079	 * Pairs with the smp_store_release() in finish_lock_switch().
2080	 *
2081	 * This ensures that tasks getting woken will be fully ordered against
2082	 * their previous state and preserve Program Order.
2083	 */
2084	smp_cond_load_acquire(&p->on_cpu, !VAL);
2085
2086	p->sched_contributes_to_load = !!task_contributes_to_load(p);
2087	p->state = TASK_WAKING;
2088
 
 
 
 
 
2089	cpu = select_task_rq(p, p->wake_cpu, SD_BALANCE_WAKE, wake_flags);
2090	if (task_cpu(p) != cpu) {
2091		wake_flags |= WF_MIGRATED;
2092		set_task_cpu(p, cpu);
2093	}
 
 
 
 
 
 
 
 
2094#endif /* CONFIG_SMP */
2095
2096	ttwu_queue(p, cpu, wake_flags);
2097stat:
2098	ttwu_stat(p, cpu, wake_flags);
2099out:
2100	raw_spin_unlock_irqrestore(&p->pi_lock, flags);
2101
2102	return success;
2103}
2104
2105/**
2106 * try_to_wake_up_local - try to wake up a local task with rq lock held
2107 * @p: the thread to be awakened
2108 * @cookie: context's cookie for pinning
2109 *
2110 * Put @p on the run-queue if it's not already there. The caller must
2111 * ensure that this_rq() is locked, @p is bound to this_rq() and not
2112 * the current task.
2113 */
2114static void try_to_wake_up_local(struct task_struct *p, struct pin_cookie cookie)
2115{
2116	struct rq *rq = task_rq(p);
2117
2118	if (WARN_ON_ONCE(rq != this_rq()) ||
2119	    WARN_ON_ONCE(p == current))
2120		return;
2121
2122	lockdep_assert_held(&rq->lock);
2123
2124	if (!raw_spin_trylock(&p->pi_lock)) {
2125		/*
2126		 * This is OK, because current is on_cpu, which avoids it being
2127		 * picked for load-balance and preemption/IRQs are still
2128		 * disabled avoiding further scheduler activity on it and we've
2129		 * not yet picked a replacement task.
2130		 */
2131		lockdep_unpin_lock(&rq->lock, cookie);
2132		raw_spin_unlock(&rq->lock);
2133		raw_spin_lock(&p->pi_lock);
2134		raw_spin_lock(&rq->lock);
2135		lockdep_repin_lock(&rq->lock, cookie);
2136	}
2137
2138	if (!(p->state & TASK_NORMAL))
2139		goto out;
2140
2141	trace_sched_waking(p);
2142
2143	if (!task_on_rq_queued(p))
2144		ttwu_activate(rq, p, ENQUEUE_WAKEUP);
 
 
 
 
 
2145
2146	ttwu_do_wakeup(rq, p, 0, cookie);
2147	ttwu_stat(p, smp_processor_id(), 0);
2148out:
2149	raw_spin_unlock(&p->pi_lock);
2150}
2151
2152/**
2153 * wake_up_process - Wake up a specific process
2154 * @p: The process to be woken up.
2155 *
2156 * Attempt to wake up the nominated process and move it to the set of runnable
2157 * processes.
2158 *
2159 * Return: 1 if the process was woken up, 0 if it was already running.
2160 *
2161 * It may be assumed that this function implies a write memory barrier before
2162 * changing the task state if and only if any tasks are woken up.
2163 */
2164int wake_up_process(struct task_struct *p)
2165{
2166	return try_to_wake_up(p, TASK_NORMAL, 0);
2167}
2168EXPORT_SYMBOL(wake_up_process);
2169
2170int wake_up_state(struct task_struct *p, unsigned int state)
2171{
2172	return try_to_wake_up(p, state, 0);
2173}
2174
2175/*
2176 * This function clears the sched_dl_entity static params.
2177 */
2178void __dl_clear_params(struct task_struct *p)
2179{
2180	struct sched_dl_entity *dl_se = &p->dl;
2181
2182	dl_se->dl_runtime = 0;
2183	dl_se->dl_deadline = 0;
2184	dl_se->dl_period = 0;
2185	dl_se->flags = 0;
2186	dl_se->dl_bw = 0;
2187
2188	dl_se->dl_throttled = 0;
2189	dl_se->dl_yielded = 0;
2190}
2191
2192/*
2193 * Perform scheduler related setup for a newly forked process p.
2194 * p is forked by current.
2195 *
2196 * __sched_fork() is basic setup used by init_idle() too:
2197 */
2198static void __sched_fork(unsigned long clone_flags, struct task_struct *p)
2199{
2200	p->on_rq			= 0;
2201
2202	p->se.on_rq			= 0;
2203	p->se.exec_start		= 0;
2204	p->se.sum_exec_runtime		= 0;
2205	p->se.prev_sum_exec_runtime	= 0;
2206	p->se.nr_migrations		= 0;
2207	p->se.vruntime			= 0;
2208	INIT_LIST_HEAD(&p->se.group_node);
2209
2210#ifdef CONFIG_FAIR_GROUP_SCHED
2211	p->se.cfs_rq			= NULL;
2212#endif
2213
2214#ifdef CONFIG_SCHEDSTATS
2215	/* Even if schedstat is disabled, there should not be garbage */
2216	memset(&p->se.statistics, 0, sizeof(p->se.statistics));
2217#endif
2218
2219	RB_CLEAR_NODE(&p->dl.rb_node);
2220	init_dl_task_timer(&p->dl);
 
2221	__dl_clear_params(p);
2222
2223	INIT_LIST_HEAD(&p->rt.run_list);
2224	p->rt.timeout		= 0;
2225	p->rt.time_slice	= sched_rr_timeslice;
2226	p->rt.on_rq		= 0;
2227	p->rt.on_list		= 0;
2228
2229#ifdef CONFIG_PREEMPT_NOTIFIERS
2230	INIT_HLIST_HEAD(&p->preempt_notifiers);
2231#endif
2232
2233#ifdef CONFIG_NUMA_BALANCING
2234	if (p->mm && atomic_read(&p->mm->mm_users) == 1) {
2235		p->mm->numa_next_scan = jiffies + msecs_to_jiffies(sysctl_numa_balancing_scan_delay);
2236		p->mm->numa_scan_seq = 0;
2237	}
2238
2239	if (clone_flags & CLONE_VM)
2240		p->numa_preferred_nid = current->numa_preferred_nid;
2241	else
2242		p->numa_preferred_nid = -1;
2243
2244	p->node_stamp = 0ULL;
2245	p->numa_scan_seq = p->mm ? p->mm->numa_scan_seq : 0;
2246	p->numa_scan_period = sysctl_numa_balancing_scan_delay;
2247	p->numa_work.next = &p->numa_work;
2248	p->numa_faults = NULL;
2249	p->last_task_numa_placement = 0;
2250	p->last_sum_exec_runtime = 0;
2251
2252	p->numa_group = NULL;
2253#endif /* CONFIG_NUMA_BALANCING */
2254}
2255
2256DEFINE_STATIC_KEY_FALSE(sched_numa_balancing);
2257
2258#ifdef CONFIG_NUMA_BALANCING
2259
2260void set_numabalancing_state(bool enabled)
2261{
2262	if (enabled)
2263		static_branch_enable(&sched_numa_balancing);
2264	else
2265		static_branch_disable(&sched_numa_balancing);
2266}
2267
2268#ifdef CONFIG_PROC_SYSCTL
2269int sysctl_numa_balancing(struct ctl_table *table, int write,
2270			 void __user *buffer, size_t *lenp, loff_t *ppos)
2271{
2272	struct ctl_table t;
2273	int err;
2274	int state = static_branch_likely(&sched_numa_balancing);
2275
2276	if (write && !capable(CAP_SYS_ADMIN))
2277		return -EPERM;
2278
2279	t = *table;
2280	t.data = &state;
2281	err = proc_dointvec_minmax(&t, write, buffer, lenp, ppos);
2282	if (err < 0)
2283		return err;
2284	if (write)
2285		set_numabalancing_state(state);
2286	return err;
2287}
2288#endif
2289#endif
2290
2291#ifdef CONFIG_SCHEDSTATS
2292
2293DEFINE_STATIC_KEY_FALSE(sched_schedstats);
2294static bool __initdata __sched_schedstats = false;
2295
2296static void set_schedstats(bool enabled)
2297{
2298	if (enabled)
2299		static_branch_enable(&sched_schedstats);
2300	else
2301		static_branch_disable(&sched_schedstats);
2302}
2303
2304void force_schedstat_enabled(void)
2305{
2306	if (!schedstat_enabled()) {
2307		pr_info("kernel profiling enabled schedstats, disable via kernel.sched_schedstats.\n");
2308		static_branch_enable(&sched_schedstats);
2309	}
2310}
2311
2312static int __init setup_schedstats(char *str)
2313{
2314	int ret = 0;
2315	if (!str)
2316		goto out;
2317
2318	/*
2319	 * This code is called before jump labels have been set up, so we can't
2320	 * change the static branch directly just yet.  Instead set a temporary
2321	 * variable so init_schedstats() can do it later.
2322	 */
2323	if (!strcmp(str, "enable")) {
2324		__sched_schedstats = true;
2325		ret = 1;
2326	} else if (!strcmp(str, "disable")) {
2327		__sched_schedstats = false;
2328		ret = 1;
2329	}
2330out:
2331	if (!ret)
2332		pr_warn("Unable to parse schedstats=\n");
2333
2334	return ret;
2335}
2336__setup("schedstats=", setup_schedstats);
2337
2338static void __init init_schedstats(void)
2339{
2340	set_schedstats(__sched_schedstats);
2341}
2342
2343#ifdef CONFIG_PROC_SYSCTL
2344int sysctl_schedstats(struct ctl_table *table, int write,
2345			 void __user *buffer, size_t *lenp, loff_t *ppos)
2346{
2347	struct ctl_table t;
2348	int err;
2349	int state = static_branch_likely(&sched_schedstats);
2350
2351	if (write && !capable(CAP_SYS_ADMIN))
2352		return -EPERM;
2353
2354	t = *table;
2355	t.data = &state;
2356	err = proc_dointvec_minmax(&t, write, buffer, lenp, ppos);
2357	if (err < 0)
2358		return err;
2359	if (write)
2360		set_schedstats(state);
2361	return err;
2362}
2363#endif /* CONFIG_PROC_SYSCTL */
2364#else  /* !CONFIG_SCHEDSTATS */
2365static inline void init_schedstats(void) {}
2366#endif /* CONFIG_SCHEDSTATS */
2367
2368/*
2369 * fork()/clone()-time setup:
2370 */
2371int sched_fork(unsigned long clone_flags, struct task_struct *p)
2372{
2373	unsigned long flags;
2374	int cpu = get_cpu();
2375
2376	__sched_fork(clone_flags, p);
2377	/*
2378	 * We mark the process as NEW here. This guarantees that
2379	 * nobody will actually run it, and a signal or other external
2380	 * event cannot wake it up and insert it on the runqueue either.
2381	 */
2382	p->state = TASK_NEW;
2383
2384	/*
2385	 * Make sure we do not leak PI boosting priority to the child.
2386	 */
2387	p->prio = current->normal_prio;
2388
2389	/*
2390	 * Revert to default priority/policy on fork if requested.
2391	 */
2392	if (unlikely(p->sched_reset_on_fork)) {
2393		if (task_has_dl_policy(p) || task_has_rt_policy(p)) {
2394			p->policy = SCHED_NORMAL;
2395			p->static_prio = NICE_TO_PRIO(0);
2396			p->rt_priority = 0;
2397		} else if (PRIO_TO_NICE(p->static_prio) < 0)
2398			p->static_prio = NICE_TO_PRIO(0);
2399
2400		p->prio = p->normal_prio = __normal_prio(p);
2401		set_load_weight(p);
2402
2403		/*
2404		 * We don't need the reset flag anymore after the fork. It has
2405		 * fulfilled its duty:
2406		 */
2407		p->sched_reset_on_fork = 0;
2408	}
2409
2410	if (dl_prio(p->prio)) {
2411		put_cpu();
2412		return -EAGAIN;
2413	} else if (rt_prio(p->prio)) {
2414		p->sched_class = &rt_sched_class;
2415	} else {
2416		p->sched_class = &fair_sched_class;
2417	}
2418
2419	init_entity_runnable_average(&p->se);
2420
2421	/*
2422	 * The child is not yet in the pid-hash so no cgroup attach races,
2423	 * and the cgroup is pinned to this child due to cgroup_fork()
2424	 * is ran before sched_fork().
2425	 *
2426	 * Silence PROVE_RCU.
2427	 */
2428	raw_spin_lock_irqsave(&p->pi_lock, flags);
2429	/*
2430	 * We're setting the cpu for the first time, we don't migrate,
2431	 * so use __set_task_cpu().
2432	 */
2433	__set_task_cpu(p, cpu);
2434	if (p->sched_class->task_fork)
2435		p->sched_class->task_fork(p);
2436	raw_spin_unlock_irqrestore(&p->pi_lock, flags);
2437
2438#ifdef CONFIG_SCHED_INFO
2439	if (likely(sched_info_on()))
2440		memset(&p->sched_info, 0, sizeof(p->sched_info));
2441#endif
2442#if defined(CONFIG_SMP)
2443	p->on_cpu = 0;
2444#endif
2445	init_task_preempt_count(p);
2446#ifdef CONFIG_SMP
2447	plist_node_init(&p->pushable_tasks, MAX_PRIO);
2448	RB_CLEAR_NODE(&p->pushable_dl_tasks);
2449#endif
2450
2451	put_cpu();
2452	return 0;
2453}
2454
2455unsigned long to_ratio(u64 period, u64 runtime)
2456{
2457	if (runtime == RUNTIME_INF)
2458		return 1ULL << 20;
2459
2460	/*
2461	 * Doing this here saves a lot of checks in all
2462	 * the calling paths, and returning zero seems
2463	 * safe for them anyway.
2464	 */
2465	if (period == 0)
2466		return 0;
2467
2468	return div64_u64(runtime << 20, period);
2469}
2470
2471#ifdef CONFIG_SMP
2472inline struct dl_bw *dl_bw_of(int i)
2473{
2474	RCU_LOCKDEP_WARN(!rcu_read_lock_sched_held(),
2475			 "sched RCU must be held");
2476	return &cpu_rq(i)->rd->dl_bw;
2477}
2478
2479static inline int dl_bw_cpus(int i)
2480{
2481	struct root_domain *rd = cpu_rq(i)->rd;
2482	int cpus = 0;
2483
2484	RCU_LOCKDEP_WARN(!rcu_read_lock_sched_held(),
2485			 "sched RCU must be held");
2486	for_each_cpu_and(i, rd->span, cpu_active_mask)
2487		cpus++;
2488
2489	return cpus;
2490}
2491#else
2492inline struct dl_bw *dl_bw_of(int i)
2493{
2494	return &cpu_rq(i)->dl.dl_bw;
2495}
2496
2497static inline int dl_bw_cpus(int i)
2498{
2499	return 1;
2500}
2501#endif
2502
2503/*
2504 * We must be sure that accepting a new task (or allowing changing the
2505 * parameters of an existing one) is consistent with the bandwidth
2506 * constraints. If yes, this function also accordingly updates the currently
2507 * allocated bandwidth to reflect the new situation.
2508 *
2509 * This function is called while holding p's rq->lock.
2510 *
2511 * XXX we should delay bw change until the task's 0-lag point, see
2512 * __setparam_dl().
2513 */
2514static int dl_overflow(struct task_struct *p, int policy,
2515		       const struct sched_attr *attr)
2516{
2517
2518	struct dl_bw *dl_b = dl_bw_of(task_cpu(p));
2519	u64 period = attr->sched_period ?: attr->sched_deadline;
2520	u64 runtime = attr->sched_runtime;
2521	u64 new_bw = dl_policy(policy) ? to_ratio(period, runtime) : 0;
2522	int cpus, err = -1;
2523
2524	/* !deadline task may carry old deadline bandwidth */
2525	if (new_bw == p->dl.dl_bw && task_has_dl_policy(p))
2526		return 0;
2527
2528	/*
2529	 * Either if a task, enters, leave, or stays -deadline but changes
2530	 * its parameters, we may need to update accordingly the total
2531	 * allocated bandwidth of the container.
2532	 */
2533	raw_spin_lock(&dl_b->lock);
2534	cpus = dl_bw_cpus(task_cpu(p));
2535	if (dl_policy(policy) && !task_has_dl_policy(p) &&
2536	    !__dl_overflow(dl_b, cpus, 0, new_bw)) {
2537		__dl_add(dl_b, new_bw);
2538		err = 0;
2539	} else if (dl_policy(policy) && task_has_dl_policy(p) &&
2540		   !__dl_overflow(dl_b, cpus, p->dl.dl_bw, new_bw)) {
2541		__dl_clear(dl_b, p->dl.dl_bw);
2542		__dl_add(dl_b, new_bw);
2543		err = 0;
2544	} else if (!dl_policy(policy) && task_has_dl_policy(p)) {
2545		__dl_clear(dl_b, p->dl.dl_bw);
2546		err = 0;
2547	}
2548	raw_spin_unlock(&dl_b->lock);
2549
2550	return err;
2551}
2552
2553extern void init_dl_bw(struct dl_bw *dl_b);
2554
2555/*
2556 * wake_up_new_task - wake up a newly created task for the first time.
2557 *
2558 * This function will do some initial scheduler statistics housekeeping
2559 * that must be done for every newly created context, then puts the task
2560 * on the runqueue and wakes it.
2561 */
2562void wake_up_new_task(struct task_struct *p)
2563{
2564	struct rq_flags rf;
2565	struct rq *rq;
2566
2567	raw_spin_lock_irqsave(&p->pi_lock, rf.flags);
2568	p->state = TASK_RUNNING;
2569#ifdef CONFIG_SMP
2570	/*
2571	 * Fork balancing, do it here and not earlier because:
2572	 *  - cpus_allowed can change in the fork path
2573	 *  - any previously selected cpu might disappear through hotplug
2574	 *
2575	 * Use __set_task_cpu() to avoid calling sched_class::migrate_task_rq,
2576	 * as we're not fully set-up yet.
2577	 */
 
2578	__set_task_cpu(p, select_task_rq(p, task_cpu(p), SD_BALANCE_FORK, 0));
2579#endif
2580	rq = __task_rq_lock(p, &rf);
 
2581	post_init_entity_util_avg(&p->se);
2582
2583	activate_task(rq, p, 0);
2584	p->on_rq = TASK_ON_RQ_QUEUED;
2585	trace_sched_wakeup_new(p);
2586	check_preempt_curr(rq, p, WF_FORK);
2587#ifdef CONFIG_SMP
2588	if (p->sched_class->task_woken) {
2589		/*
2590		 * Nothing relies on rq->lock after this, so its fine to
2591		 * drop it.
2592		 */
2593		lockdep_unpin_lock(&rq->lock, rf.cookie);
2594		p->sched_class->task_woken(rq, p);
2595		lockdep_repin_lock(&rq->lock, rf.cookie);
2596	}
2597#endif
2598	task_rq_unlock(rq, p, &rf);
2599}
2600
2601#ifdef CONFIG_PREEMPT_NOTIFIERS
2602
2603static struct static_key preempt_notifier_key = STATIC_KEY_INIT_FALSE;
2604
2605void preempt_notifier_inc(void)
2606{
2607	static_key_slow_inc(&preempt_notifier_key);
2608}
2609EXPORT_SYMBOL_GPL(preempt_notifier_inc);
2610
2611void preempt_notifier_dec(void)
2612{
2613	static_key_slow_dec(&preempt_notifier_key);
2614}
2615EXPORT_SYMBOL_GPL(preempt_notifier_dec);
2616
2617/**
2618 * preempt_notifier_register - tell me when current is being preempted & rescheduled
2619 * @notifier: notifier struct to register
2620 */
2621void preempt_notifier_register(struct preempt_notifier *notifier)
2622{
2623	if (!static_key_false(&preempt_notifier_key))
2624		WARN(1, "registering preempt_notifier while notifiers disabled\n");
2625
2626	hlist_add_head(&notifier->link, &current->preempt_notifiers);
2627}
2628EXPORT_SYMBOL_GPL(preempt_notifier_register);
2629
2630/**
2631 * preempt_notifier_unregister - no longer interested in preemption notifications
2632 * @notifier: notifier struct to unregister
2633 *
2634 * This is *not* safe to call from within a preemption notifier.
2635 */
2636void preempt_notifier_unregister(struct preempt_notifier *notifier)
2637{
2638	hlist_del(&notifier->link);
2639}
2640EXPORT_SYMBOL_GPL(preempt_notifier_unregister);
2641
2642static void __fire_sched_in_preempt_notifiers(struct task_struct *curr)
2643{
2644	struct preempt_notifier *notifier;
2645
2646	hlist_for_each_entry(notifier, &curr->preempt_notifiers, link)
2647		notifier->ops->sched_in(notifier, raw_smp_processor_id());
2648}
2649
2650static __always_inline void fire_sched_in_preempt_notifiers(struct task_struct *curr)
2651{
2652	if (static_key_false(&preempt_notifier_key))
2653		__fire_sched_in_preempt_notifiers(curr);
2654}
2655
2656static void
2657__fire_sched_out_preempt_notifiers(struct task_struct *curr,
2658				   struct task_struct *next)
2659{
2660	struct preempt_notifier *notifier;
2661
2662	hlist_for_each_entry(notifier, &curr->preempt_notifiers, link)
2663		notifier->ops->sched_out(notifier, next);
2664}
2665
2666static __always_inline void
2667fire_sched_out_preempt_notifiers(struct task_struct *curr,
2668				 struct task_struct *next)
2669{
2670	if (static_key_false(&preempt_notifier_key))
2671		__fire_sched_out_preempt_notifiers(curr, next);
2672}
2673
2674#else /* !CONFIG_PREEMPT_NOTIFIERS */
2675
2676static inline void fire_sched_in_preempt_notifiers(struct task_struct *curr)
2677{
2678}
2679
2680static inline void
2681fire_sched_out_preempt_notifiers(struct task_struct *curr,
2682				 struct task_struct *next)
2683{
2684}
2685
2686#endif /* CONFIG_PREEMPT_NOTIFIERS */
2687
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
2688/**
2689 * prepare_task_switch - prepare to switch tasks
2690 * @rq: the runqueue preparing to switch
2691 * @prev: the current task that is being switched out
2692 * @next: the task we are going to switch to.
2693 *
2694 * This is called with the rq lock held and interrupts off. It must
2695 * be paired with a subsequent finish_task_switch after the context
2696 * switch.
2697 *
2698 * prepare_task_switch sets up locking and calls architecture specific
2699 * hooks.
2700 */
2701static inline void
2702prepare_task_switch(struct rq *rq, struct task_struct *prev,
2703		    struct task_struct *next)
2704{
2705	sched_info_switch(rq, prev, next);
2706	perf_event_task_sched_out(prev, next);
2707	fire_sched_out_preempt_notifiers(prev, next);
2708	prepare_lock_switch(rq, next);
2709	prepare_arch_switch(next);
2710}
2711
2712/**
2713 * finish_task_switch - clean up after a task-switch
2714 * @prev: the thread we just switched away from.
2715 *
2716 * finish_task_switch must be called after the context switch, paired
2717 * with a prepare_task_switch call before the context switch.
2718 * finish_task_switch will reconcile locking set up by prepare_task_switch,
2719 * and do any other architecture-specific cleanup actions.
2720 *
2721 * Note that we may have delayed dropping an mm in context_switch(). If
2722 * so, we finish that here outside of the runqueue lock. (Doing it
2723 * with the lock held can cause deadlocks; see schedule() for
2724 * details.)
2725 *
2726 * The context switch have flipped the stack from under us and restored the
2727 * local variables which were saved when this task called schedule() in the
2728 * past. prev == current is still correct but we need to recalculate this_rq
2729 * because prev may have moved to another CPU.
2730 */
2731static struct rq *finish_task_switch(struct task_struct *prev)
2732	__releases(rq->lock)
2733{
2734	struct rq *rq = this_rq();
2735	struct mm_struct *mm = rq->prev_mm;
2736	long prev_state;
2737
2738	/*
2739	 * The previous task will have left us with a preempt_count of 2
2740	 * because it left us after:
2741	 *
2742	 *	schedule()
2743	 *	  preempt_disable();			// 1
2744	 *	  __schedule()
2745	 *	    raw_spin_lock_irq(&rq->lock)	// 2
2746	 *
2747	 * Also, see FORK_PREEMPT_COUNT.
2748	 */
2749	if (WARN_ONCE(preempt_count() != 2*PREEMPT_DISABLE_OFFSET,
2750		      "corrupted preempt_count: %s/%d/0x%x\n",
2751		      current->comm, current->pid, preempt_count()))
2752		preempt_count_set(FORK_PREEMPT_COUNT);
2753
2754	rq->prev_mm = NULL;
2755
2756	/*
2757	 * A task struct has one reference for the use as "current".
2758	 * If a task dies, then it sets TASK_DEAD in tsk->state and calls
2759	 * schedule one last time. The schedule call will never return, and
2760	 * the scheduled task must drop that reference.
2761	 *
2762	 * We must observe prev->state before clearing prev->on_cpu (in
2763	 * finish_lock_switch), otherwise a concurrent wakeup can get prev
2764	 * running on another CPU and we could rave with its RUNNING -> DEAD
2765	 * transition, resulting in a double drop.
2766	 */
2767	prev_state = prev->state;
2768	vtime_task_switch(prev);
2769	perf_event_task_sched_in(prev, current);
2770	finish_lock_switch(rq, prev);
 
2771	finish_arch_post_lock_switch();
2772
2773	fire_sched_in_preempt_notifiers(current);
2774	if (mm)
 
 
 
 
 
 
 
 
 
 
 
 
 
2775		mmdrop(mm);
2776	if (unlikely(prev_state == TASK_DEAD)) {
2777		if (prev->sched_class->task_dead)
2778			prev->sched_class->task_dead(prev);
 
 
 
2779
2780		/*
2781		 * Remove function-return probe instances associated with this
2782		 * task and put them back on the free list.
2783		 */
2784		kprobe_flush_task(prev);
 
 
 
2785
2786		/* Task is done with its stack. */
2787		put_task_stack(prev);
2788
2789		put_task_struct(prev);
 
 
 
2790	}
2791
2792	tick_nohz_task_switch();
2793	return rq;
2794}
2795
2796#ifdef CONFIG_SMP
2797
2798/* rq->lock is NOT held, but preemption is disabled */
2799static void __balance_callback(struct rq *rq)
2800{
2801	struct callback_head *head, *next;
2802	void (*func)(struct rq *rq);
2803	unsigned long flags;
2804
2805	raw_spin_lock_irqsave(&rq->lock, flags);
2806	head = rq->balance_callback;
2807	rq->balance_callback = NULL;
2808	while (head) {
2809		func = (void (*)(struct rq *))head->func;
2810		next = head->next;
2811		head->next = NULL;
2812		head = next;
2813
2814		func(rq);
2815	}
2816	raw_spin_unlock_irqrestore(&rq->lock, flags);
2817}
2818
2819static inline void balance_callback(struct rq *rq)
2820{
2821	if (unlikely(rq->balance_callback))
2822		__balance_callback(rq);
2823}
2824
2825#else
2826
2827static inline void balance_callback(struct rq *rq)
2828{
2829}
2830
2831#endif
2832
2833/**
2834 * schedule_tail - first thing a freshly forked thread must call.
2835 * @prev: the thread we just switched away from.
2836 */
2837asmlinkage __visible void schedule_tail(struct task_struct *prev)
2838	__releases(rq->lock)
2839{
2840	struct rq *rq;
2841
2842	/*
2843	 * New tasks start with FORK_PREEMPT_COUNT, see there and
2844	 * finish_task_switch() for details.
2845	 *
2846	 * finish_task_switch() will drop rq->lock() and lower preempt_count
2847	 * and the preempt_enable() will end up enabling preemption (on
2848	 * PREEMPT_COUNT kernels).
2849	 */
2850
2851	rq = finish_task_switch(prev);
2852	balance_callback(rq);
2853	preempt_enable();
2854
2855	if (current->set_child_tid)
2856		put_user(task_pid_vnr(current), current->set_child_tid);
2857}
2858
2859/*
2860 * context_switch - switch to the new MM and the new thread's register state.
2861 */
2862static __always_inline struct rq *
2863context_switch(struct rq *rq, struct task_struct *prev,
2864	       struct task_struct *next, struct pin_cookie cookie)
2865{
2866	struct mm_struct *mm, *oldmm;
2867
2868	prepare_task_switch(rq, prev, next);
2869
2870	mm = next->mm;
2871	oldmm = prev->active_mm;
2872	/*
2873	 * For paravirt, this is coupled with an exit in switch_to to
2874	 * combine the page table reload and the switch backend into
2875	 * one hypercall.
2876	 */
2877	arch_start_context_switch(prev);
2878
 
 
 
 
 
 
 
2879	if (!mm) {
2880		next->active_mm = oldmm;
2881		atomic_inc(&oldmm->mm_count);
2882		enter_lazy_tlb(oldmm, next);
2883	} else
2884		switch_mm_irqs_off(oldmm, mm, next);
2885
2886	if (!prev->mm) {
2887		prev->active_mm = NULL;
2888		rq->prev_mm = oldmm;
2889	}
2890	/*
2891	 * Since the runqueue lock will be released by the next
2892	 * task (which is an invalid locking op but in the case
2893	 * of the scheduler it's an obvious special-case), so we
2894	 * do an early lockdep release here:
2895	 */
2896	lockdep_unpin_lock(&rq->lock, cookie);
2897	spin_release(&rq->lock.dep_map, 1, _THIS_IP_);
2898
2899	/* Here we just switch the register state and the stack. */
2900	switch_to(prev, next, prev);
2901	barrier();
2902
2903	return finish_task_switch(prev);
2904}
2905
2906/*
2907 * nr_running and nr_context_switches:
2908 *
2909 * externally visible scheduler statistics: current number of runnable
2910 * threads, total number of context switches performed since bootup.
2911 */
2912unsigned long nr_running(void)
2913{
2914	unsigned long i, sum = 0;
2915
2916	for_each_online_cpu(i)
2917		sum += cpu_rq(i)->nr_running;
2918
2919	return sum;
2920}
2921
2922/*
2923 * Check if only the current task is running on the cpu.
2924 *
2925 * Caution: this function does not check that the caller has disabled
2926 * preemption, thus the result might have a time-of-check-to-time-of-use
2927 * race.  The caller is responsible to use it correctly, for example:
2928 *
2929 * - from a non-preemptable section (of course)
2930 *
2931 * - from a thread that is bound to a single CPU
2932 *
2933 * - in a loop with very short iterations (e.g. a polling loop)
2934 */
2935bool single_task_running(void)
2936{
2937	return raw_rq()->nr_running == 1;
2938}
2939EXPORT_SYMBOL(single_task_running);
2940
2941unsigned long long nr_context_switches(void)
2942{
2943	int i;
2944	unsigned long long sum = 0;
2945
2946	for_each_possible_cpu(i)
2947		sum += cpu_rq(i)->nr_switches;
2948
2949	return sum;
2950}
2951
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
2952unsigned long nr_iowait(void)
2953{
2954	unsigned long i, sum = 0;
2955
2956	for_each_possible_cpu(i)
2957		sum += atomic_read(&cpu_rq(i)->nr_iowait);
2958
2959	return sum;
2960}
2961
 
 
 
 
 
 
 
2962unsigned long nr_iowait_cpu(int cpu)
2963{
2964	struct rq *this = cpu_rq(cpu);
2965	return atomic_read(&this->nr_iowait);
2966}
2967
2968void get_iowait_load(unsigned long *nr_waiters, unsigned long *load)
2969{
2970	struct rq *rq = this_rq();
2971	*nr_waiters = atomic_read(&rq->nr_iowait);
2972	*load = rq->load.weight;
2973}
2974
2975#ifdef CONFIG_SMP
2976
2977/*
2978 * sched_exec - execve() is a valuable balancing opportunity, because at
2979 * this point the task has the smallest effective memory and cache footprint.
2980 */
2981void sched_exec(void)
2982{
2983	struct task_struct *p = current;
2984	unsigned long flags;
2985	int dest_cpu;
2986
2987	raw_spin_lock_irqsave(&p->pi_lock, flags);
2988	dest_cpu = p->sched_class->select_task_rq(p, task_cpu(p), SD_BALANCE_EXEC, 0);
2989	if (dest_cpu == smp_processor_id())
2990		goto unlock;
2991
2992	if (likely(cpu_active(dest_cpu))) {
2993		struct migration_arg arg = { p, dest_cpu };
2994
2995		raw_spin_unlock_irqrestore(&p->pi_lock, flags);
2996		stop_one_cpu(task_cpu(p), migration_cpu_stop, &arg);
2997		return;
2998	}
2999unlock:
3000	raw_spin_unlock_irqrestore(&p->pi_lock, flags);
3001}
3002
3003#endif
3004
3005DEFINE_PER_CPU(struct kernel_stat, kstat);
3006DEFINE_PER_CPU(struct kernel_cpustat, kernel_cpustat);
3007
3008EXPORT_PER_CPU_SYMBOL(kstat);
3009EXPORT_PER_CPU_SYMBOL(kernel_cpustat);
3010
3011/*
3012 * The function fair_sched_class.update_curr accesses the struct curr
3013 * and its field curr->exec_start; when called from task_sched_runtime(),
3014 * we observe a high rate of cache misses in practice.
3015 * Prefetching this data results in improved performance.
3016 */
3017static inline void prefetch_curr_exec_start(struct task_struct *p)
3018{
3019#ifdef CONFIG_FAIR_GROUP_SCHED
3020	struct sched_entity *curr = (&p->se)->cfs_rq->curr;
3021#else
3022	struct sched_entity *curr = (&task_rq(p)->cfs)->curr;
3023#endif
3024	prefetch(curr);
3025	prefetch(&curr->exec_start);
3026}
3027
3028/*
3029 * Return accounted runtime for the task.
3030 * In case the task is currently running, return the runtime plus current's
3031 * pending runtime that have not been accounted yet.
3032 */
3033unsigned long long task_sched_runtime(struct task_struct *p)
3034{
3035	struct rq_flags rf;
3036	struct rq *rq;
3037	u64 ns;
3038
3039#if defined(CONFIG_64BIT) && defined(CONFIG_SMP)
3040	/*
3041	 * 64-bit doesn't need locks to atomically read a 64bit value.
3042	 * So we have a optimization chance when the task's delta_exec is 0.
3043	 * Reading ->on_cpu is racy, but this is ok.
3044	 *
3045	 * If we race with it leaving cpu, we'll take a lock. So we're correct.
3046	 * If we race with it entering cpu, unaccounted time is 0. This is
3047	 * indistinguishable from the read occurring a few cycles earlier.
3048	 * If we see ->on_cpu without ->on_rq, the task is leaving, and has
3049	 * been accounted, so we're correct here as well.
3050	 */
3051	if (!p->on_cpu || !task_on_rq_queued(p))
3052		return p->se.sum_exec_runtime;
3053#endif
3054
3055	rq = task_rq_lock(p, &rf);
3056	/*
3057	 * Must be ->curr _and_ ->on_rq.  If dequeued, we would
3058	 * project cycles that may never be accounted to this
3059	 * thread, breaking clock_gettime().
3060	 */
3061	if (task_current(rq, p) && task_on_rq_queued(p)) {
3062		prefetch_curr_exec_start(p);
3063		update_rq_clock(rq);
3064		p->sched_class->update_curr(rq);
3065	}
3066	ns = p->se.sum_exec_runtime;
3067	task_rq_unlock(rq, p, &rf);
3068
3069	return ns;
3070}
3071
3072/*
3073 * This function gets called by the timer code, with HZ frequency.
3074 * We call it with interrupts disabled.
3075 */
3076void scheduler_tick(void)
3077{
3078	int cpu = smp_processor_id();
3079	struct rq *rq = cpu_rq(cpu);
3080	struct task_struct *curr = rq->curr;
 
3081
3082	sched_clock_tick();
3083
3084	raw_spin_lock(&rq->lock);
 
3085	update_rq_clock(rq);
3086	curr->sched_class->task_tick(rq, curr, 0);
3087	cpu_load_update_active(rq);
3088	calc_global_load_tick(rq);
3089	raw_spin_unlock(&rq->lock);
 
3090
3091	perf_event_task_tick();
3092
3093#ifdef CONFIG_SMP
3094	rq->idle_balance = idle_cpu(cpu);
3095	trigger_load_balance(rq);
3096#endif
3097	rq_last_tick_reset(rq);
3098}
3099
3100#ifdef CONFIG_NO_HZ_FULL
3101/**
3102 * scheduler_tick_max_deferment
3103 *
3104 * Keep at least one tick per second when a single
3105 * active task is running because the scheduler doesn't
3106 * yet completely support full dynticks environment.
3107 *
3108 * This makes sure that uptime, CFS vruntime, load
3109 * balancing, etc... continue to move forward, even
3110 * with a very low granularity.
3111 *
3112 * Return: Maximum deferment in nanoseconds.
3113 */
3114u64 scheduler_tick_max_deferment(void)
3115{
3116	struct rq *rq = this_rq();
3117	unsigned long next, now = READ_ONCE(jiffies);
 
 
 
3118
3119	next = rq->last_sched_tick + HZ;
 
 
 
 
 
 
 
 
 
3120
3121	if (time_before_eq(next, now))
3122		return 0;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
3123
3124	return jiffies_to_nsecs(next - now);
 
 
 
3125}
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
3126#endif
3127
3128#if defined(CONFIG_PREEMPT) && (defined(CONFIG_DEBUG_PREEMPT) || \
3129				defined(CONFIG_PREEMPT_TRACER))
3130/*
3131 * If the value passed in is equal to the current preempt count
3132 * then we just disabled preemption. Start timing the latency.
3133 */
3134static inline void preempt_latency_start(int val)
3135{
3136	if (preempt_count() == val) {
3137		unsigned long ip = get_lock_parent_ip();
3138#ifdef CONFIG_DEBUG_PREEMPT
3139		current->preempt_disable_ip = ip;
3140#endif
3141		trace_preempt_off(CALLER_ADDR0, ip);
3142	}
3143}
3144
3145void preempt_count_add(int val)
3146{
3147#ifdef CONFIG_DEBUG_PREEMPT
3148	/*
3149	 * Underflow?
3150	 */
3151	if (DEBUG_LOCKS_WARN_ON((preempt_count() < 0)))
3152		return;
3153#endif
3154	__preempt_count_add(val);
3155#ifdef CONFIG_DEBUG_PREEMPT
3156	/*
3157	 * Spinlock count overflowing soon?
3158	 */
3159	DEBUG_LOCKS_WARN_ON((preempt_count() & PREEMPT_MASK) >=
3160				PREEMPT_MASK - 10);
3161#endif
3162	preempt_latency_start(val);
3163}
3164EXPORT_SYMBOL(preempt_count_add);
3165NOKPROBE_SYMBOL(preempt_count_add);
3166
3167/*
3168 * If the value passed in equals to the current preempt count
3169 * then we just enabled preemption. Stop timing the latency.
3170 */
3171static inline void preempt_latency_stop(int val)
3172{
3173	if (preempt_count() == val)
3174		trace_preempt_on(CALLER_ADDR0, get_lock_parent_ip());
3175}
3176
3177void preempt_count_sub(int val)
3178{
3179#ifdef CONFIG_DEBUG_PREEMPT
3180	/*
3181	 * Underflow?
3182	 */
3183	if (DEBUG_LOCKS_WARN_ON(val > preempt_count()))
3184		return;
3185	/*
3186	 * Is the spinlock portion underflowing?
3187	 */
3188	if (DEBUG_LOCKS_WARN_ON((val < PREEMPT_MASK) &&
3189			!(preempt_count() & PREEMPT_MASK)))
3190		return;
3191#endif
3192
3193	preempt_latency_stop(val);
3194	__preempt_count_sub(val);
3195}
3196EXPORT_SYMBOL(preempt_count_sub);
3197NOKPROBE_SYMBOL(preempt_count_sub);
3198
3199#else
3200static inline void preempt_latency_start(int val) { }
3201static inline void preempt_latency_stop(int val) { }
3202#endif
3203
 
 
 
 
 
 
 
 
 
3204/*
3205 * Print scheduling while atomic bug:
3206 */
3207static noinline void __schedule_bug(struct task_struct *prev)
3208{
3209	/* Save this before calling printk(), since that will clobber it */
3210	unsigned long preempt_disable_ip = get_preempt_disable_ip(current);
3211
3212	if (oops_in_progress)
3213		return;
3214
3215	printk(KERN_ERR "BUG: scheduling while atomic: %s/%d/0x%08x\n",
3216		prev->comm, prev->pid, preempt_count());
3217
3218	debug_show_held_locks(prev);
3219	print_modules();
3220	if (irqs_disabled())
3221		print_irqtrace_events(prev);
3222	if (IS_ENABLED(CONFIG_DEBUG_PREEMPT)
3223	    && in_atomic_preempt_off()) {
3224		pr_err("Preemption disabled at:");
3225		print_ip_sym(preempt_disable_ip);
3226		pr_cont("\n");
3227	}
3228	if (panic_on_warn)
3229		panic("scheduling while atomic\n");
3230
3231	dump_stack();
3232	add_taint(TAINT_WARN, LOCKDEP_STILL_OK);
3233}
3234
3235/*
3236 * Various schedule()-time debugging checks and statistics:
3237 */
3238static inline void schedule_debug(struct task_struct *prev)
3239{
3240#ifdef CONFIG_SCHED_STACK_END_CHECK
3241	if (task_stack_end_corrupted(prev))
3242		panic("corrupted stack end detected inside scheduler\n");
3243#endif
3244
3245	if (unlikely(in_atomic_preempt_off())) {
3246		__schedule_bug(prev);
3247		preempt_count_set(PREEMPT_DISABLED);
3248	}
3249	rcu_sleep_check();
3250
3251	profile_hit(SCHED_PROFILING, __builtin_return_address(0));
3252
3253	schedstat_inc(this_rq()->sched_count);
3254}
3255
3256/*
3257 * Pick up the highest-prio task:
3258 */
3259static inline struct task_struct *
3260pick_next_task(struct rq *rq, struct task_struct *prev, struct pin_cookie cookie)
3261{
3262	const struct sched_class *class = &fair_sched_class;
3263	struct task_struct *p;
3264
3265	/*
3266	 * Optimization: we know that if all tasks are in
3267	 * the fair class we can call that function directly:
 
 
3268	 */
3269	if (likely(prev->sched_class == class &&
 
3270		   rq->nr_running == rq->cfs.h_nr_running)) {
3271		p = fair_sched_class.pick_next_task(rq, prev, cookie);
 
3272		if (unlikely(p == RETRY_TASK))
3273			goto again;
3274
3275		/* assumes fair_sched_class->next == idle_sched_class */
3276		if (unlikely(!p))
3277			p = idle_sched_class.pick_next_task(rq, prev, cookie);
3278
3279		return p;
3280	}
3281
3282again:
3283	for_each_class(class) {
3284		p = class->pick_next_task(rq, prev, cookie);
3285		if (p) {
3286			if (unlikely(p == RETRY_TASK))
3287				goto again;
3288			return p;
3289		}
3290	}
3291
3292	BUG(); /* the idle class will always have a runnable task */
 
3293}
3294
3295/*
3296 * __schedule() is the main scheduler function.
3297 *
3298 * The main means of driving the scheduler and thus entering this function are:
3299 *
3300 *   1. Explicit blocking: mutex, semaphore, waitqueue, etc.
3301 *
3302 *   2. TIF_NEED_RESCHED flag is checked on interrupt and userspace return
3303 *      paths. For example, see arch/x86/entry_64.S.
3304 *
3305 *      To drive preemption between tasks, the scheduler sets the flag in timer
3306 *      interrupt handler scheduler_tick().
3307 *
3308 *   3. Wakeups don't really cause entry into schedule(). They add a
3309 *      task to the run-queue and that's it.
3310 *
3311 *      Now, if the new task added to the run-queue preempts the current
3312 *      task, then the wakeup sets TIF_NEED_RESCHED and schedule() gets
3313 *      called on the nearest possible occasion:
3314 *
3315 *       - If the kernel is preemptible (CONFIG_PREEMPT=y):
3316 *
3317 *         - in syscall or exception context, at the next outmost
3318 *           preempt_enable(). (this might be as soon as the wake_up()'s
3319 *           spin_unlock()!)
3320 *
3321 *         - in IRQ context, return from interrupt-handler to
3322 *           preemptible context
3323 *
3324 *       - If the kernel is not preemptible (CONFIG_PREEMPT is not set)
3325 *         then at the next:
3326 *
3327 *          - cond_resched() call
3328 *          - explicit schedule() call
3329 *          - return from syscall or exception to user-space
3330 *          - return from interrupt-handler to user-space
3331 *
3332 * WARNING: must be called with preemption disabled!
3333 */
3334static void __sched notrace __schedule(bool preempt)
3335{
3336	struct task_struct *prev, *next;
3337	unsigned long *switch_count;
3338	struct pin_cookie cookie;
3339	struct rq *rq;
3340	int cpu;
3341
3342	cpu = smp_processor_id();
3343	rq = cpu_rq(cpu);
3344	prev = rq->curr;
3345
3346	schedule_debug(prev);
3347
3348	if (sched_feat(HRTICK))
3349		hrtick_clear(rq);
3350
3351	local_irq_disable();
3352	rcu_note_context_switch();
3353
3354	/*
3355	 * Make sure that signal_pending_state()->signal_pending() below
3356	 * can't be reordered with __set_current_state(TASK_INTERRUPTIBLE)
3357	 * done by the caller to avoid the race with signal_wake_up().
 
 
 
3358	 */
3359	smp_mb__before_spinlock();
3360	raw_spin_lock(&rq->lock);
3361	cookie = lockdep_pin_lock(&rq->lock);
3362
3363	rq->clock_skip_update <<= 1; /* promote REQ to ACT */
 
 
3364
3365	switch_count = &prev->nivcsw;
3366	if (!preempt && prev->state) {
3367		if (unlikely(signal_pending_state(prev->state, prev))) {
3368			prev->state = TASK_RUNNING;
3369		} else {
3370			deactivate_task(rq, prev, DEQUEUE_SLEEP);
3371			prev->on_rq = 0;
3372
 
 
 
 
 
3373			/*
3374			 * If a worker went to sleep, notify and ask workqueue
3375			 * whether it wants to wake up a task to maintain
3376			 * concurrency.
3377			 */
3378			if (prev->flags & PF_WQ_WORKER) {
3379				struct task_struct *to_wakeup;
3380
3381				to_wakeup = wq_worker_sleeping(prev);
3382				if (to_wakeup)
3383					try_to_wake_up_local(to_wakeup, cookie);
3384			}
3385		}
3386		switch_count = &prev->nvcsw;
3387	}
3388
3389	if (task_on_rq_queued(prev))
3390		update_rq_clock(rq);
3391
3392	next = pick_next_task(rq, prev, cookie);
3393	clear_tsk_need_resched(prev);
3394	clear_preempt_need_resched();
3395	rq->clock_skip_update = 0;
3396
3397	if (likely(prev != next)) {
3398		rq->nr_switches++;
3399		rq->curr = next;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
3400		++*switch_count;
3401
3402		trace_sched_switch(preempt, prev, next);
3403		rq = context_switch(rq, prev, next, cookie); /* unlocks the rq */
 
 
3404	} else {
3405		lockdep_unpin_lock(&rq->lock, cookie);
3406		raw_spin_unlock_irq(&rq->lock);
3407	}
3408
3409	balance_callback(rq);
3410}
3411
3412void __noreturn do_task_dead(void)
3413{
3414	/*
3415	 * The setting of TASK_RUNNING by try_to_wake_up() may be delayed
3416	 * when the following two conditions become true.
3417	 *   - There is race condition of mmap_sem (It is acquired by
3418	 *     exit_mm()), and
3419	 *   - SMI occurs before setting TASK_RUNINNG.
3420	 *     (or hypervisor of virtual machine switches to other guest)
3421	 *  As a result, we may become TASK_RUNNING after becoming TASK_DEAD
3422	 *
3423	 * To avoid it, we have to wait for releasing tsk->pi_lock which
3424	 * is held by try_to_wake_up()
3425	 */
3426	smp_mb();
3427	raw_spin_unlock_wait(&current->pi_lock);
3428
3429	/* causes final put_task_struct in finish_task_switch(). */
3430	__set_current_state(TASK_DEAD);
3431	current->flags |= PF_NOFREEZE;	/* tell freezer to ignore us */
3432	__schedule(false);
3433	BUG();
3434	/* Avoid "noreturn function does return".  */
 
3435	for (;;)
3436		cpu_relax();	/* For when BUG is null */
3437}
3438
3439static inline void sched_submit_work(struct task_struct *tsk)
3440{
3441	if (!tsk->state || tsk_is_pi_blocked(tsk))
3442		return;
3443	/*
3444	 * If we are going to sleep and we have plugged IO queued,
3445	 * make sure to submit it to avoid deadlocks.
3446	 */
3447	if (blk_needs_flush_plug(tsk))
3448		blk_schedule_flush_plug(tsk);
3449}
3450
3451asmlinkage __visible void __sched schedule(void)
3452{
3453	struct task_struct *tsk = current;
3454
3455	sched_submit_work(tsk);
3456	do {
3457		preempt_disable();
3458		__schedule(false);
3459		sched_preempt_enable_no_resched();
3460	} while (need_resched());
3461}
3462EXPORT_SYMBOL(schedule);
3463
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
3464#ifdef CONFIG_CONTEXT_TRACKING
3465asmlinkage __visible void __sched schedule_user(void)
3466{
3467	/*
3468	 * If we come here after a random call to set_need_resched(),
3469	 * or we have been woken up remotely but the IPI has not yet arrived,
3470	 * we haven't yet exited the RCU idle mode. Do it here manually until
3471	 * we find a better solution.
3472	 *
3473	 * NB: There are buggy callers of this function.  Ideally we
3474	 * should warn if prev_state != CONTEXT_USER, but that will trigger
3475	 * too frequently to make sense yet.
3476	 */
3477	enum ctx_state prev_state = exception_enter();
3478	schedule();
3479	exception_exit(prev_state);
3480}
3481#endif
3482
3483/**
3484 * schedule_preempt_disabled - called with preemption disabled
3485 *
3486 * Returns with preemption disabled. Note: preempt_count must be 1
3487 */
3488void __sched schedule_preempt_disabled(void)
3489{
3490	sched_preempt_enable_no_resched();
3491	schedule();
3492	preempt_disable();
3493}
3494
3495static void __sched notrace preempt_schedule_common(void)
3496{
3497	do {
3498		/*
3499		 * Because the function tracer can trace preempt_count_sub()
3500		 * and it also uses preempt_enable/disable_notrace(), if
3501		 * NEED_RESCHED is set, the preempt_enable_notrace() called
3502		 * by the function tracer will call this function again and
3503		 * cause infinite recursion.
3504		 *
3505		 * Preemption must be disabled here before the function
3506		 * tracer can trace. Break up preempt_disable() into two
3507		 * calls. One to disable preemption without fear of being
3508		 * traced. The other to still record the preemption latency,
3509		 * which can also be traced by the function tracer.
3510		 */
3511		preempt_disable_notrace();
3512		preempt_latency_start(1);
3513		__schedule(true);
3514		preempt_latency_stop(1);
3515		preempt_enable_no_resched_notrace();
3516
3517		/*
3518		 * Check again in case we missed a preemption opportunity
3519		 * between schedule and now.
3520		 */
3521	} while (need_resched());
3522}
3523
3524#ifdef CONFIG_PREEMPT
3525/*
3526 * this is the entry point to schedule() from in-kernel preemption
3527 * off of preempt_enable. Kernel preemptions off return from interrupt
3528 * occur there and call schedule directly.
3529 */
3530asmlinkage __visible void __sched notrace preempt_schedule(void)
3531{
3532	/*
3533	 * If there is a non-zero preempt_count or interrupts are disabled,
3534	 * we do not want to preempt the current task. Just return..
3535	 */
3536	if (likely(!preemptible()))
3537		return;
3538
3539	preempt_schedule_common();
3540}
3541NOKPROBE_SYMBOL(preempt_schedule);
3542EXPORT_SYMBOL(preempt_schedule);
3543
3544/**
3545 * preempt_schedule_notrace - preempt_schedule called by tracing
3546 *
3547 * The tracing infrastructure uses preempt_enable_notrace to prevent
3548 * recursion and tracing preempt enabling caused by the tracing
3549 * infrastructure itself. But as tracing can happen in areas coming
3550 * from userspace or just about to enter userspace, a preempt enable
3551 * can occur before user_exit() is called. This will cause the scheduler
3552 * to be called when the system is still in usermode.
3553 *
3554 * To prevent this, the preempt_enable_notrace will use this function
3555 * instead of preempt_schedule() to exit user context if needed before
3556 * calling the scheduler.
3557 */
3558asmlinkage __visible void __sched notrace preempt_schedule_notrace(void)
3559{
3560	enum ctx_state prev_ctx;
3561
3562	if (likely(!preemptible()))
3563		return;
3564
3565	do {
3566		/*
3567		 * Because the function tracer can trace preempt_count_sub()
3568		 * and it also uses preempt_enable/disable_notrace(), if
3569		 * NEED_RESCHED is set, the preempt_enable_notrace() called
3570		 * by the function tracer will call this function again and
3571		 * cause infinite recursion.
3572		 *
3573		 * Preemption must be disabled here before the function
3574		 * tracer can trace. Break up preempt_disable() into two
3575		 * calls. One to disable preemption without fear of being
3576		 * traced. The other to still record the preemption latency,
3577		 * which can also be traced by the function tracer.
3578		 */
3579		preempt_disable_notrace();
3580		preempt_latency_start(1);
3581		/*
3582		 * Needs preempt disabled in case user_exit() is traced
3583		 * and the tracer calls preempt_enable_notrace() causing
3584		 * an infinite recursion.
3585		 */
3586		prev_ctx = exception_enter();
3587		__schedule(true);
3588		exception_exit(prev_ctx);
3589
3590		preempt_latency_stop(1);
3591		preempt_enable_no_resched_notrace();
3592	} while (need_resched());
3593}
3594EXPORT_SYMBOL_GPL(preempt_schedule_notrace);
3595
3596#endif /* CONFIG_PREEMPT */
3597
3598/*
3599 * this is the entry point to schedule() from kernel preemption
3600 * off of irq context.
3601 * Note, that this is called and return with irqs disabled. This will
3602 * protect us against recursive calling from irq.
3603 */
3604asmlinkage __visible void __sched preempt_schedule_irq(void)
3605{
3606	enum ctx_state prev_state;
3607
3608	/* Catch callers which need to be fixed */
3609	BUG_ON(preempt_count() || !irqs_disabled());
3610
3611	prev_state = exception_enter();
3612
3613	do {
3614		preempt_disable();
3615		local_irq_enable();
3616		__schedule(true);
3617		local_irq_disable();
3618		sched_preempt_enable_no_resched();
3619	} while (need_resched());
3620
3621	exception_exit(prev_state);
3622}
3623
3624int default_wake_function(wait_queue_t *curr, unsigned mode, int wake_flags,
3625			  void *key)
3626{
3627	return try_to_wake_up(curr->private, mode, wake_flags);
3628}
3629EXPORT_SYMBOL(default_wake_function);
3630
3631#ifdef CONFIG_RT_MUTEXES
3632
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
3633/*
3634 * rt_mutex_setprio - set the current priority of a task
3635 * @p: task
3636 * @prio: prio value (kernel-internal form)
3637 *
3638 * This function changes the 'effective' priority of a task. It does
3639 * not touch ->normal_prio like __setscheduler().
3640 *
3641 * Used by the rt_mutex code to implement priority inheritance
3642 * logic. Call site only calls if the priority of the task changed.
3643 */
3644void rt_mutex_setprio(struct task_struct *p, int prio)
3645{
3646	int oldprio, queued, running, queue_flag = DEQUEUE_SAVE | DEQUEUE_MOVE;
 
3647	const struct sched_class *prev_class;
3648	struct rq_flags rf;
3649	struct rq *rq;
3650
3651	BUG_ON(prio > MAX_PRIO);
 
 
 
 
 
 
 
3652
3653	rq = __task_rq_lock(p, &rf);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
3654
3655	/*
3656	 * Idle task boosting is a nono in general. There is one
3657	 * exception, when PREEMPT_RT and NOHZ is active:
3658	 *
3659	 * The idle task calls get_next_timer_interrupt() and holds
3660	 * the timer wheel base->lock on the CPU and another CPU wants
3661	 * to access the timer (probably to cancel it). We can safely
3662	 * ignore the boosting request, as the idle CPU runs this code
3663	 * with interrupts disabled and will complete the lock
3664	 * protected section without being interrupted. So there is no
3665	 * real need to boost.
3666	 */
3667	if (unlikely(p == rq->idle)) {
3668		WARN_ON(p != rq->curr);
3669		WARN_ON(p->pi_blocked_on);
3670		goto out_unlock;
3671	}
3672
3673	trace_sched_pi_setprio(p, prio);
3674	oldprio = p->prio;
3675
3676	if (oldprio == prio)
3677		queue_flag &= ~DEQUEUE_MOVE;
3678
3679	prev_class = p->sched_class;
3680	queued = task_on_rq_queued(p);
3681	running = task_current(rq, p);
3682	if (queued)
3683		dequeue_task(rq, p, queue_flag);
3684	if (running)
3685		put_prev_task(rq, p);
3686
3687	/*
3688	 * Boosting condition are:
3689	 * 1. -rt task is running and holds mutex A
3690	 *      --> -dl task blocks on mutex A
3691	 *
3692	 * 2. -dl task is running and holds mutex A
3693	 *      --> -dl task blocks on mutex A and could preempt the
3694	 *          running task
3695	 */
3696	if (dl_prio(prio)) {
3697		struct task_struct *pi_task = rt_mutex_get_top_task(p);
3698		if (!dl_prio(p->normal_prio) ||
3699		    (pi_task && dl_entity_preempt(&pi_task->dl, &p->dl))) {
3700			p->dl.dl_boosted = 1;
3701			queue_flag |= ENQUEUE_REPLENISH;
3702		} else
3703			p->dl.dl_boosted = 0;
3704		p->sched_class = &dl_sched_class;
3705	} else if (rt_prio(prio)) {
3706		if (dl_prio(oldprio))
3707			p->dl.dl_boosted = 0;
3708		if (oldprio < prio)
3709			queue_flag |= ENQUEUE_HEAD;
3710		p->sched_class = &rt_sched_class;
3711	} else {
3712		if (dl_prio(oldprio))
3713			p->dl.dl_boosted = 0;
3714		if (rt_prio(oldprio))
3715			p->rt.timeout = 0;
3716		p->sched_class = &fair_sched_class;
3717	}
3718
3719	p->prio = prio;
3720
3721	if (queued)
3722		enqueue_task(rq, p, queue_flag);
3723	if (running)
3724		set_curr_task(rq, p);
3725
3726	check_class_changed(rq, p, prev_class, oldprio);
3727out_unlock:
3728	preempt_disable(); /* avoid rq from going away on us */
 
3729	__task_rq_unlock(rq, &rf);
3730
3731	balance_callback(rq);
3732	preempt_enable();
3733}
 
 
 
 
 
3734#endif
3735
3736void set_user_nice(struct task_struct *p, long nice)
3737{
3738	bool queued, running;
3739	int old_prio, delta;
3740	struct rq_flags rf;
3741	struct rq *rq;
3742
3743	if (task_nice(p) == nice || nice < MIN_NICE || nice > MAX_NICE)
3744		return;
3745	/*
3746	 * We have to be careful, if called from sys_setpriority(),
3747	 * the task might be in the middle of scheduling on another CPU.
3748	 */
3749	rq = task_rq_lock(p, &rf);
 
 
3750	/*
3751	 * The RT priorities are set via sched_setscheduler(), but we still
3752	 * allow the 'normal' nice value to be set - but as expected
3753	 * it wont have any effect on scheduling until the task is
3754	 * SCHED_DEADLINE, SCHED_FIFO or SCHED_RR:
3755	 */
3756	if (task_has_dl_policy(p) || task_has_rt_policy(p)) {
3757		p->static_prio = NICE_TO_PRIO(nice);
3758		goto out_unlock;
3759	}
3760	queued = task_on_rq_queued(p);
3761	running = task_current(rq, p);
3762	if (queued)
3763		dequeue_task(rq, p, DEQUEUE_SAVE);
3764	if (running)
3765		put_prev_task(rq, p);
3766
3767	p->static_prio = NICE_TO_PRIO(nice);
3768	set_load_weight(p);
3769	old_prio = p->prio;
3770	p->prio = effective_prio(p);
3771	delta = p->prio - old_prio;
3772
3773	if (queued) {
3774		enqueue_task(rq, p, ENQUEUE_RESTORE);
3775		/*
3776		 * If the task increased its priority or is running and
3777		 * lowered its priority, then reschedule its CPU:
3778		 */
3779		if (delta < 0 || (delta > 0 && task_running(rq, p)))
3780			resched_curr(rq);
3781	}
3782	if (running)
3783		set_curr_task(rq, p);
3784out_unlock:
3785	task_rq_unlock(rq, p, &rf);
3786}
3787EXPORT_SYMBOL(set_user_nice);
3788
3789/*
3790 * can_nice - check if a task can reduce its nice value
3791 * @p: task
3792 * @nice: nice value
3793 */
3794int can_nice(const struct task_struct *p, const int nice)
3795{
3796	/* convert nice value [19,-20] to rlimit style value [1,40] */
3797	int nice_rlim = nice_to_rlimit(nice);
3798
3799	return (nice_rlim <= task_rlimit(p, RLIMIT_NICE) ||
3800		capable(CAP_SYS_NICE));
3801}
3802
3803#ifdef __ARCH_WANT_SYS_NICE
3804
3805/*
3806 * sys_nice - change the priority of the current process.
3807 * @increment: priority increment
3808 *
3809 * sys_setpriority is a more generic, but much slower function that
3810 * does similar things.
3811 */
3812SYSCALL_DEFINE1(nice, int, increment)
3813{
3814	long nice, retval;
3815
3816	/*
3817	 * Setpriority might change our priority at the same moment.
3818	 * We don't have to worry. Conceptually one call occurs first
3819	 * and we have a single winner.
3820	 */
3821	increment = clamp(increment, -NICE_WIDTH, NICE_WIDTH);
3822	nice = task_nice(current) + increment;
3823
3824	nice = clamp_val(nice, MIN_NICE, MAX_NICE);
3825	if (increment < 0 && !can_nice(current, nice))
3826		return -EPERM;
3827
3828	retval = security_task_setnice(current, nice);
3829	if (retval)
3830		return retval;
3831
3832	set_user_nice(current, nice);
3833	return 0;
3834}
3835
3836#endif
3837
3838/**
3839 * task_prio - return the priority value of a given task.
3840 * @p: the task in question.
3841 *
3842 * Return: The priority value as seen by users in /proc.
3843 * RT tasks are offset by -200. Normal tasks are centered
3844 * around 0, value goes from -16 to +15.
3845 */
3846int task_prio(const struct task_struct *p)
3847{
3848	return p->prio - MAX_RT_PRIO;
3849}
3850
3851/**
3852 * idle_cpu - is a given cpu idle currently?
3853 * @cpu: the processor in question.
3854 *
3855 * Return: 1 if the CPU is currently idle. 0 otherwise.
3856 */
3857int idle_cpu(int cpu)
3858{
3859	struct rq *rq = cpu_rq(cpu);
3860
3861	if (rq->curr != rq->idle)
3862		return 0;
3863
3864	if (rq->nr_running)
3865		return 0;
3866
3867#ifdef CONFIG_SMP
3868	if (!llist_empty(&rq->wake_list))
3869		return 0;
3870#endif
3871
3872	return 1;
3873}
3874
3875/**
3876 * idle_task - return the idle task for a given cpu.
3877 * @cpu: the processor in question.
3878 *
3879 * Return: The idle task for the cpu @cpu.
3880 */
3881struct task_struct *idle_task(int cpu)
3882{
3883	return cpu_rq(cpu)->idle;
3884}
3885
3886/**
3887 * find_process_by_pid - find a process with a matching PID value.
3888 * @pid: the pid in question.
3889 *
3890 * The task of @pid, if found. %NULL otherwise.
3891 */
3892static struct task_struct *find_process_by_pid(pid_t pid)
3893{
3894	return pid ? find_task_by_vpid(pid) : current;
3895}
3896
3897/*
3898 * This function initializes the sched_dl_entity of a newly becoming
3899 * SCHED_DEADLINE task.
3900 *
3901 * Only the static values are considered here, the actual runtime and the
3902 * absolute deadline will be properly calculated when the task is enqueued
3903 * for the first time with its new policy.
3904 */
3905static void
3906__setparam_dl(struct task_struct *p, const struct sched_attr *attr)
3907{
3908	struct sched_dl_entity *dl_se = &p->dl;
3909
3910	dl_se->dl_runtime = attr->sched_runtime;
3911	dl_se->dl_deadline = attr->sched_deadline;
3912	dl_se->dl_period = attr->sched_period ?: dl_se->dl_deadline;
3913	dl_se->flags = attr->sched_flags;
3914	dl_se->dl_bw = to_ratio(dl_se->dl_period, dl_se->dl_runtime);
3915
3916	/*
3917	 * Changing the parameters of a task is 'tricky' and we're not doing
3918	 * the correct thing -- also see task_dead_dl() and switched_from_dl().
3919	 *
3920	 * What we SHOULD do is delay the bandwidth release until the 0-lag
3921	 * point. This would include retaining the task_struct until that time
3922	 * and change dl_overflow() to not immediately decrement the current
3923	 * amount.
3924	 *
3925	 * Instead we retain the current runtime/deadline and let the new
3926	 * parameters take effect after the current reservation period lapses.
3927	 * This is safe (albeit pessimistic) because the 0-lag point is always
3928	 * before the current scheduling deadline.
3929	 *
3930	 * We can still have temporary overloads because we do not delay the
3931	 * change in bandwidth until that time; so admission control is
3932	 * not on the safe side. It does however guarantee tasks will never
3933	 * consume more than promised.
3934	 */
3935}
3936
3937/*
3938 * sched_setparam() passes in -1 for its policy, to let the functions
3939 * it calls know not to change it.
3940 */
3941#define SETPARAM_POLICY	-1
3942
3943static void __setscheduler_params(struct task_struct *p,
3944		const struct sched_attr *attr)
3945{
3946	int policy = attr->sched_policy;
3947
3948	if (policy == SETPARAM_POLICY)
3949		policy = p->policy;
3950
3951	p->policy = policy;
3952
3953	if (dl_policy(policy))
3954		__setparam_dl(p, attr);
3955	else if (fair_policy(policy))
3956		p->static_prio = NICE_TO_PRIO(attr->sched_nice);
3957
3958	/*
3959	 * __sched_setscheduler() ensures attr->sched_priority == 0 when
3960	 * !rt_policy. Always setting this ensures that things like
3961	 * getparam()/getattr() don't report silly values for !rt tasks.
3962	 */
3963	p->rt_priority = attr->sched_priority;
3964	p->normal_prio = normal_prio(p);
3965	set_load_weight(p);
3966}
3967
3968/* Actually do priority change: must hold pi & rq lock. */
3969static void __setscheduler(struct rq *rq, struct task_struct *p,
3970			   const struct sched_attr *attr, bool keep_boost)
3971{
3972	__setscheduler_params(p, attr);
3973
3974	/*
3975	 * Keep a potential priority boosting if called from
3976	 * sched_setscheduler().
3977	 */
 
3978	if (keep_boost)
3979		p->prio = rt_mutex_get_effective_prio(p, normal_prio(p));
3980	else
3981		p->prio = normal_prio(p);
3982
3983	if (dl_prio(p->prio))
3984		p->sched_class = &dl_sched_class;
3985	else if (rt_prio(p->prio))
3986		p->sched_class = &rt_sched_class;
3987	else
3988		p->sched_class = &fair_sched_class;
3989}
3990
3991static void
3992__getparam_dl(struct task_struct *p, struct sched_attr *attr)
3993{
3994	struct sched_dl_entity *dl_se = &p->dl;
3995
3996	attr->sched_priority = p->rt_priority;
3997	attr->sched_runtime = dl_se->dl_runtime;
3998	attr->sched_deadline = dl_se->dl_deadline;
3999	attr->sched_period = dl_se->dl_period;
4000	attr->sched_flags = dl_se->flags;
4001}
4002
4003/*
4004 * This function validates the new parameters of a -deadline task.
4005 * We ask for the deadline not being zero, and greater or equal
4006 * than the runtime, as well as the period of being zero or
4007 * greater than deadline. Furthermore, we have to be sure that
4008 * user parameters are above the internal resolution of 1us (we
4009 * check sched_runtime only since it is always the smaller one) and
4010 * below 2^63 ns (we have to check both sched_deadline and
4011 * sched_period, as the latter can be zero).
4012 */
4013static bool
4014__checkparam_dl(const struct sched_attr *attr)
4015{
4016	/* deadline != 0 */
4017	if (attr->sched_deadline == 0)
4018		return false;
4019
4020	/*
4021	 * Since we truncate DL_SCALE bits, make sure we're at least
4022	 * that big.
4023	 */
4024	if (attr->sched_runtime < (1ULL << DL_SCALE))
4025		return false;
4026
4027	/*
4028	 * Since we use the MSB for wrap-around and sign issues, make
4029	 * sure it's not set (mind that period can be equal to zero).
4030	 */
4031	if (attr->sched_deadline & (1ULL << 63) ||
4032	    attr->sched_period & (1ULL << 63))
4033		return false;
4034
4035	/* runtime <= deadline <= period (if period != 0) */
4036	if ((attr->sched_period != 0 &&
4037	     attr->sched_period < attr->sched_deadline) ||
4038	    attr->sched_deadline < attr->sched_runtime)
4039		return false;
4040
4041	return true;
4042}
4043
4044/*
4045 * check the target process has a UID that matches the current process's
4046 */
4047static bool check_same_owner(struct task_struct *p)
4048{
4049	const struct cred *cred = current_cred(), *pcred;
4050	bool match;
4051
4052	rcu_read_lock();
4053	pcred = __task_cred(p);
4054	match = (uid_eq(cred->euid, pcred->euid) ||
4055		 uid_eq(cred->euid, pcred->uid));
4056	rcu_read_unlock();
4057	return match;
4058}
4059
4060static bool dl_param_changed(struct task_struct *p,
4061		const struct sched_attr *attr)
4062{
4063	struct sched_dl_entity *dl_se = &p->dl;
4064
4065	if (dl_se->dl_runtime != attr->sched_runtime ||
4066		dl_se->dl_deadline != attr->sched_deadline ||
4067		dl_se->dl_period != attr->sched_period ||
4068		dl_se->flags != attr->sched_flags)
4069		return true;
4070
4071	return false;
4072}
4073
4074static int __sched_setscheduler(struct task_struct *p,
4075				const struct sched_attr *attr,
4076				bool user, bool pi)
4077{
4078	int newprio = dl_policy(attr->sched_policy) ? MAX_DL_PRIO - 1 :
4079		      MAX_RT_PRIO - 1 - attr->sched_priority;
4080	int retval, oldprio, oldpolicy = -1, queued, running;
4081	int new_effective_prio, policy = attr->sched_policy;
4082	const struct sched_class *prev_class;
4083	struct rq_flags rf;
4084	int reset_on_fork;
4085	int queue_flags = DEQUEUE_SAVE | DEQUEUE_MOVE;
4086	struct rq *rq;
4087
4088	/* may grab non-irq protected spin_locks */
4089	BUG_ON(in_interrupt());
4090recheck:
4091	/* double check policy once rq lock held */
4092	if (policy < 0) {
4093		reset_on_fork = p->sched_reset_on_fork;
4094		policy = oldpolicy = p->policy;
4095	} else {
4096		reset_on_fork = !!(attr->sched_flags & SCHED_FLAG_RESET_ON_FORK);
4097
4098		if (!valid_policy(policy))
4099			return -EINVAL;
4100	}
4101
4102	if (attr->sched_flags & ~(SCHED_FLAG_RESET_ON_FORK))
4103		return -EINVAL;
4104
4105	/*
4106	 * Valid priorities for SCHED_FIFO and SCHED_RR are
4107	 * 1..MAX_USER_RT_PRIO-1, valid priority for SCHED_NORMAL,
4108	 * SCHED_BATCH and SCHED_IDLE is 0.
4109	 */
4110	if ((p->mm && attr->sched_priority > MAX_USER_RT_PRIO-1) ||
4111	    (!p->mm && attr->sched_priority > MAX_RT_PRIO-1))
4112		return -EINVAL;
4113	if ((dl_policy(policy) && !__checkparam_dl(attr)) ||
4114	    (rt_policy(policy) != (attr->sched_priority != 0)))
4115		return -EINVAL;
4116
4117	/*
4118	 * Allow unprivileged RT tasks to decrease priority:
4119	 */
4120	if (user && !capable(CAP_SYS_NICE)) {
4121		if (fair_policy(policy)) {
4122			if (attr->sched_nice < task_nice(p) &&
4123			    !can_nice(p, attr->sched_nice))
4124				return -EPERM;
4125		}
4126
4127		if (rt_policy(policy)) {
4128			unsigned long rlim_rtprio =
4129					task_rlimit(p, RLIMIT_RTPRIO);
4130
4131			/* can't set/change the rt policy */
4132			if (policy != p->policy && !rlim_rtprio)
4133				return -EPERM;
4134
4135			/* can't increase priority */
4136			if (attr->sched_priority > p->rt_priority &&
4137			    attr->sched_priority > rlim_rtprio)
4138				return -EPERM;
4139		}
4140
4141		 /*
4142		  * Can't set/change SCHED_DEADLINE policy at all for now
4143		  * (safest behavior); in the future we would like to allow
4144		  * unprivileged DL tasks to increase their relative deadline
4145		  * or reduce their runtime (both ways reducing utilization)
4146		  */
4147		if (dl_policy(policy))
4148			return -EPERM;
4149
4150		/*
4151		 * Treat SCHED_IDLE as nice 20. Only allow a switch to
4152		 * SCHED_NORMAL if the RLIMIT_NICE would normally permit it.
4153		 */
4154		if (idle_policy(p->policy) && !idle_policy(policy)) {
4155			if (!can_nice(p, task_nice(p)))
4156				return -EPERM;
4157		}
4158
4159		/* can't change other user's priorities */
4160		if (!check_same_owner(p))
4161			return -EPERM;
4162
4163		/* Normal users shall not reset the sched_reset_on_fork flag */
4164		if (p->sched_reset_on_fork && !reset_on_fork)
4165			return -EPERM;
4166	}
4167
4168	if (user) {
 
 
 
4169		retval = security_task_setscheduler(p);
4170		if (retval)
4171			return retval;
4172	}
4173
4174	/*
4175	 * make sure no PI-waiters arrive (or leave) while we are
4176	 * changing the priority of the task:
4177	 *
4178	 * To be able to change p->policy safely, the appropriate
4179	 * runqueue lock must be held.
4180	 */
4181	rq = task_rq_lock(p, &rf);
 
4182
4183	/*
4184	 * Changing the policy of the stop threads its a very bad idea
4185	 */
4186	if (p == rq->stop) {
4187		task_rq_unlock(rq, p, &rf);
4188		return -EINVAL;
4189	}
4190
4191	/*
4192	 * If not changing anything there's no need to proceed further,
4193	 * but store a possible modification of reset_on_fork.
4194	 */
4195	if (unlikely(policy == p->policy)) {
4196		if (fair_policy(policy) && attr->sched_nice != task_nice(p))
4197			goto change;
4198		if (rt_policy(policy) && attr->sched_priority != p->rt_priority)
4199			goto change;
4200		if (dl_policy(policy) && dl_param_changed(p, attr))
4201			goto change;
4202
4203		p->sched_reset_on_fork = reset_on_fork;
4204		task_rq_unlock(rq, p, &rf);
4205		return 0;
4206	}
4207change:
4208
4209	if (user) {
4210#ifdef CONFIG_RT_GROUP_SCHED
4211		/*
4212		 * Do not allow realtime tasks into groups that have no runtime
4213		 * assigned.
4214		 */
4215		if (rt_bandwidth_enabled() && rt_policy(policy) &&
4216				task_group(p)->rt_bandwidth.rt_runtime == 0 &&
4217				!task_group_is_autogroup(task_group(p))) {
4218			task_rq_unlock(rq, p, &rf);
4219			return -EPERM;
4220		}
4221#endif
4222#ifdef CONFIG_SMP
4223		if (dl_bandwidth_enabled() && dl_policy(policy)) {
 
4224			cpumask_t *span = rq->rd->span;
4225
4226			/*
4227			 * Don't allow tasks with an affinity mask smaller than
4228			 * the entire root_domain to become SCHED_DEADLINE. We
4229			 * will also fail if there's no bandwidth available.
4230			 */
4231			if (!cpumask_subset(span, &p->cpus_allowed) ||
4232			    rq->rd->dl_bw.bw == 0) {
4233				task_rq_unlock(rq, p, &rf);
4234				return -EPERM;
4235			}
4236		}
4237#endif
4238	}
4239
4240	/* recheck policy now with rq lock held */
4241	if (unlikely(oldpolicy != -1 && oldpolicy != p->policy)) {
4242		policy = oldpolicy = -1;
4243		task_rq_unlock(rq, p, &rf);
4244		goto recheck;
4245	}
4246
4247	/*
4248	 * If setscheduling to SCHED_DEADLINE (or changing the parameters
4249	 * of a SCHED_DEADLINE task) we need to check if enough bandwidth
4250	 * is available.
4251	 */
4252	if ((dl_policy(policy) || dl_task(p)) && dl_overflow(p, policy, attr)) {
4253		task_rq_unlock(rq, p, &rf);
4254		return -EBUSY;
4255	}
4256
4257	p->sched_reset_on_fork = reset_on_fork;
4258	oldprio = p->prio;
4259
4260	if (pi) {
4261		/*
4262		 * Take priority boosted tasks into account. If the new
4263		 * effective priority is unchanged, we just store the new
4264		 * normal parameters and do not touch the scheduler class and
4265		 * the runqueue. This will be done when the task deboost
4266		 * itself.
4267		 */
4268		new_effective_prio = rt_mutex_get_effective_prio(p, newprio);
4269		if (new_effective_prio == oldprio)
4270			queue_flags &= ~DEQUEUE_MOVE;
4271	}
4272
4273	queued = task_on_rq_queued(p);
4274	running = task_current(rq, p);
4275	if (queued)
4276		dequeue_task(rq, p, queue_flags);
4277	if (running)
4278		put_prev_task(rq, p);
4279
4280	prev_class = p->sched_class;
4281	__setscheduler(rq, p, attr, pi);
4282
4283	if (queued) {
4284		/*
4285		 * We enqueue to tail when the priority of a task is
4286		 * increased (user space view).
4287		 */
4288		if (oldprio < p->prio)
4289			queue_flags |= ENQUEUE_HEAD;
4290
4291		enqueue_task(rq, p, queue_flags);
4292	}
4293	if (running)
4294		set_curr_task(rq, p);
4295
4296	check_class_changed(rq, p, prev_class, oldprio);
4297	preempt_disable(); /* avoid rq from going away on us */
 
 
4298	task_rq_unlock(rq, p, &rf);
4299
4300	if (pi)
4301		rt_mutex_adjust_pi(p);
4302
4303	/*
4304	 * Run balance callbacks after we've adjusted the PI chain.
4305	 */
4306	balance_callback(rq);
4307	preempt_enable();
4308
4309	return 0;
4310}
4311
4312static int _sched_setscheduler(struct task_struct *p, int policy,
4313			       const struct sched_param *param, bool check)
4314{
4315	struct sched_attr attr = {
4316		.sched_policy   = policy,
4317		.sched_priority = param->sched_priority,
4318		.sched_nice	= PRIO_TO_NICE(p->static_prio),
4319	};
4320
4321	/* Fixup the legacy SCHED_RESET_ON_FORK hack. */
4322	if ((policy != SETPARAM_POLICY) && (policy & SCHED_RESET_ON_FORK)) {
4323		attr.sched_flags |= SCHED_FLAG_RESET_ON_FORK;
4324		policy &= ~SCHED_RESET_ON_FORK;
4325		attr.sched_policy = policy;
4326	}
4327
4328	return __sched_setscheduler(p, &attr, check, true);
4329}
4330/**
4331 * sched_setscheduler - change the scheduling policy and/or RT priority of a thread.
4332 * @p: the task in question.
4333 * @policy: new policy.
4334 * @param: structure containing the new RT priority.
4335 *
4336 * Return: 0 on success. An error code otherwise.
4337 *
4338 * NOTE that the task may be already dead.
4339 */
4340int sched_setscheduler(struct task_struct *p, int policy,
4341		       const struct sched_param *param)
4342{
4343	return _sched_setscheduler(p, policy, param, true);
4344}
4345EXPORT_SYMBOL_GPL(sched_setscheduler);
4346
4347int sched_setattr(struct task_struct *p, const struct sched_attr *attr)
4348{
4349	return __sched_setscheduler(p, attr, true, true);
4350}
4351EXPORT_SYMBOL_GPL(sched_setattr);
4352
 
 
 
 
 
4353/**
4354 * sched_setscheduler_nocheck - change the scheduling policy and/or RT priority of a thread from kernelspace.
4355 * @p: the task in question.
4356 * @policy: new policy.
4357 * @param: structure containing the new RT priority.
4358 *
4359 * Just like sched_setscheduler, only don't bother checking if the
4360 * current context has permission.  For example, this is needed in
4361 * stop_machine(): we create temporary high priority worker threads,
4362 * but our caller might not have that capability.
4363 *
4364 * Return: 0 on success. An error code otherwise.
4365 */
4366int sched_setscheduler_nocheck(struct task_struct *p, int policy,
4367			       const struct sched_param *param)
4368{
4369	return _sched_setscheduler(p, policy, param, false);
4370}
4371EXPORT_SYMBOL_GPL(sched_setscheduler_nocheck);
4372
4373static int
4374do_sched_setscheduler(pid_t pid, int policy, struct sched_param __user *param)
4375{
4376	struct sched_param lparam;
4377	struct task_struct *p;
4378	int retval;
4379
4380	if (!param || pid < 0)
4381		return -EINVAL;
4382	if (copy_from_user(&lparam, param, sizeof(struct sched_param)))
4383		return -EFAULT;
4384
4385	rcu_read_lock();
4386	retval = -ESRCH;
4387	p = find_process_by_pid(pid);
4388	if (p != NULL)
4389		retval = sched_setscheduler(p, policy, &lparam);
4390	rcu_read_unlock();
4391
4392	return retval;
4393}
4394
4395/*
4396 * Mimics kernel/events/core.c perf_copy_attr().
4397 */
4398static int sched_copy_attr(struct sched_attr __user *uattr,
4399			   struct sched_attr *attr)
4400{
4401	u32 size;
4402	int ret;
4403
4404	if (!access_ok(VERIFY_WRITE, uattr, SCHED_ATTR_SIZE_VER0))
4405		return -EFAULT;
4406
4407	/*
4408	 * zero the full structure, so that a short copy will be nice.
4409	 */
4410	memset(attr, 0, sizeof(*attr));
4411
4412	ret = get_user(size, &uattr->size);
4413	if (ret)
4414		return ret;
4415
4416	if (size > PAGE_SIZE)	/* silly large */
 
4417		goto err_size;
4418
4419	if (!size)		/* abi compat */
 
4420		size = SCHED_ATTR_SIZE_VER0;
4421
4422	if (size < SCHED_ATTR_SIZE_VER0)
4423		goto err_size;
4424
4425	/*
4426	 * If we're handed a bigger struct than we know of,
4427	 * ensure all the unknown bits are 0 - i.e. new
4428	 * user-space does not rely on any kernel feature
4429	 * extensions we dont know about yet.
4430	 */
4431	if (size > sizeof(*attr)) {
4432		unsigned char __user *addr;
4433		unsigned char __user *end;
4434		unsigned char val;
4435
4436		addr = (void __user *)uattr + sizeof(*attr);
4437		end  = (void __user *)uattr + size;
4438
4439		for (; addr < end; addr++) {
4440			ret = get_user(val, addr);
4441			if (ret)
4442				return ret;
4443			if (val)
4444				goto err_size;
4445		}
4446		size = sizeof(*attr);
4447	}
4448
4449	ret = copy_from_user(attr, uattr, size);
4450	if (ret)
4451		return -EFAULT;
4452
4453	/*
4454	 * XXX: do we want to be lenient like existing syscalls; or do we want
4455	 * to be strict and return an error on out-of-bounds values?
4456	 */
4457	attr->sched_nice = clamp(attr->sched_nice, MIN_NICE, MAX_NICE);
4458
4459	return 0;
4460
4461err_size:
4462	put_user(sizeof(*attr), &uattr->size);
4463	return -E2BIG;
4464}
4465
4466/**
4467 * sys_sched_setscheduler - set/change the scheduler policy and RT priority
4468 * @pid: the pid in question.
4469 * @policy: new policy.
4470 * @param: structure containing the new RT priority.
4471 *
4472 * Return: 0 on success. An error code otherwise.
4473 */
4474SYSCALL_DEFINE3(sched_setscheduler, pid_t, pid, int, policy,
4475		struct sched_param __user *, param)
4476{
4477	/* negative values for policy are not valid */
4478	if (policy < 0)
4479		return -EINVAL;
4480
4481	return do_sched_setscheduler(pid, policy, param);
4482}
4483
4484/**
4485 * sys_sched_setparam - set/change the RT priority of a thread
4486 * @pid: the pid in question.
4487 * @param: structure containing the new RT priority.
4488 *
4489 * Return: 0 on success. An error code otherwise.
4490 */
4491SYSCALL_DEFINE2(sched_setparam, pid_t, pid, struct sched_param __user *, param)
4492{
4493	return do_sched_setscheduler(pid, SETPARAM_POLICY, param);
4494}
4495
4496/**
4497 * sys_sched_setattr - same as above, but with extended sched_attr
4498 * @pid: the pid in question.
4499 * @uattr: structure containing the extended parameters.
4500 * @flags: for future extension.
4501 */
4502SYSCALL_DEFINE3(sched_setattr, pid_t, pid, struct sched_attr __user *, uattr,
4503			       unsigned int, flags)
4504{
4505	struct sched_attr attr;
4506	struct task_struct *p;
4507	int retval;
4508
4509	if (!uattr || pid < 0 || flags)
4510		return -EINVAL;
4511
4512	retval = sched_copy_attr(uattr, &attr);
4513	if (retval)
4514		return retval;
4515
4516	if ((int)attr.sched_policy < 0)
4517		return -EINVAL;
4518
4519	rcu_read_lock();
4520	retval = -ESRCH;
4521	p = find_process_by_pid(pid);
4522	if (p != NULL)
4523		retval = sched_setattr(p, &attr);
4524	rcu_read_unlock();
4525
4526	return retval;
4527}
4528
4529/**
4530 * sys_sched_getscheduler - get the policy (scheduling class) of a thread
4531 * @pid: the pid in question.
4532 *
4533 * Return: On success, the policy of the thread. Otherwise, a negative error
4534 * code.
4535 */
4536SYSCALL_DEFINE1(sched_getscheduler, pid_t, pid)
4537{
4538	struct task_struct *p;
4539	int retval;
4540
4541	if (pid < 0)
4542		return -EINVAL;
4543
4544	retval = -ESRCH;
4545	rcu_read_lock();
4546	p = find_process_by_pid(pid);
4547	if (p) {
4548		retval = security_task_getscheduler(p);
4549		if (!retval)
4550			retval = p->policy
4551				| (p->sched_reset_on_fork ? SCHED_RESET_ON_FORK : 0);
4552	}
4553	rcu_read_unlock();
4554	return retval;
4555}
4556
4557/**
4558 * sys_sched_getparam - get the RT priority of a thread
4559 * @pid: the pid in question.
4560 * @param: structure containing the RT priority.
4561 *
4562 * Return: On success, 0 and the RT priority is in @param. Otherwise, an error
4563 * code.
4564 */
4565SYSCALL_DEFINE2(sched_getparam, pid_t, pid, struct sched_param __user *, param)
4566{
4567	struct sched_param lp = { .sched_priority = 0 };
4568	struct task_struct *p;
4569	int retval;
4570
4571	if (!param || pid < 0)
4572		return -EINVAL;
4573
4574	rcu_read_lock();
4575	p = find_process_by_pid(pid);
4576	retval = -ESRCH;
4577	if (!p)
4578		goto out_unlock;
4579
4580	retval = security_task_getscheduler(p);
4581	if (retval)
4582		goto out_unlock;
4583
4584	if (task_has_rt_policy(p))
4585		lp.sched_priority = p->rt_priority;
4586	rcu_read_unlock();
4587
4588	/*
4589	 * This one might sleep, we cannot do it with a spinlock held ...
4590	 */
4591	retval = copy_to_user(param, &lp, sizeof(*param)) ? -EFAULT : 0;
4592
4593	return retval;
4594
4595out_unlock:
4596	rcu_read_unlock();
4597	return retval;
4598}
4599
4600static int sched_read_attr(struct sched_attr __user *uattr,
4601			   struct sched_attr *attr,
4602			   unsigned int usize)
4603{
4604	int ret;
4605
4606	if (!access_ok(VERIFY_WRITE, uattr, usize))
4607		return -EFAULT;
4608
4609	/*
4610	 * If we're handed a smaller struct than we know of,
4611	 * ensure all the unknown bits are 0 - i.e. old
4612	 * user-space does not get uncomplete information.
4613	 */
4614	if (usize < sizeof(*attr)) {
4615		unsigned char *addr;
4616		unsigned char *end;
4617
4618		addr = (void *)attr + usize;
4619		end  = (void *)attr + sizeof(*attr);
4620
4621		for (; addr < end; addr++) {
4622			if (*addr)
4623				return -EFBIG;
4624		}
4625
4626		attr->size = usize;
4627	}
4628
4629	ret = copy_to_user(uattr, attr, attr->size);
4630	if (ret)
4631		return -EFAULT;
4632
4633	return 0;
4634}
4635
4636/**
4637 * sys_sched_getattr - similar to sched_getparam, but with sched_attr
4638 * @pid: the pid in question.
4639 * @uattr: structure containing the extended parameters.
4640 * @size: sizeof(attr) for fwd/bwd comp.
4641 * @flags: for future extension.
4642 */
4643SYSCALL_DEFINE4(sched_getattr, pid_t, pid, struct sched_attr __user *, uattr,
4644		unsigned int, size, unsigned int, flags)
4645{
4646	struct sched_attr attr = {
4647		.size = sizeof(struct sched_attr),
4648	};
4649	struct task_struct *p;
4650	int retval;
4651
4652	if (!uattr || pid < 0 || size > PAGE_SIZE ||
4653	    size < SCHED_ATTR_SIZE_VER0 || flags)
4654		return -EINVAL;
4655
4656	rcu_read_lock();
4657	p = find_process_by_pid(pid);
4658	retval = -ESRCH;
4659	if (!p)
4660		goto out_unlock;
4661
4662	retval = security_task_getscheduler(p);
4663	if (retval)
4664		goto out_unlock;
4665
4666	attr.sched_policy = p->policy;
4667	if (p->sched_reset_on_fork)
4668		attr.sched_flags |= SCHED_FLAG_RESET_ON_FORK;
4669	if (task_has_dl_policy(p))
4670		__getparam_dl(p, &attr);
4671	else if (task_has_rt_policy(p))
4672		attr.sched_priority = p->rt_priority;
4673	else
4674		attr.sched_nice = task_nice(p);
4675
4676	rcu_read_unlock();
4677
4678	retval = sched_read_attr(uattr, &attr, size);
4679	return retval;
4680
4681out_unlock:
4682	rcu_read_unlock();
4683	return retval;
4684}
4685
4686long sched_setaffinity(pid_t pid, const struct cpumask *in_mask)
4687{
4688	cpumask_var_t cpus_allowed, new_mask;
4689	struct task_struct *p;
4690	int retval;
4691
4692	rcu_read_lock();
4693
4694	p = find_process_by_pid(pid);
4695	if (!p) {
4696		rcu_read_unlock();
4697		return -ESRCH;
4698	}
4699
4700	/* Prevent p going away */
4701	get_task_struct(p);
4702	rcu_read_unlock();
4703
4704	if (p->flags & PF_NO_SETAFFINITY) {
4705		retval = -EINVAL;
4706		goto out_put_task;
4707	}
4708	if (!alloc_cpumask_var(&cpus_allowed, GFP_KERNEL)) {
4709		retval = -ENOMEM;
4710		goto out_put_task;
4711	}
4712	if (!alloc_cpumask_var(&new_mask, GFP_KERNEL)) {
4713		retval = -ENOMEM;
4714		goto out_free_cpus_allowed;
4715	}
4716	retval = -EPERM;
4717	if (!check_same_owner(p)) {
4718		rcu_read_lock();
4719		if (!ns_capable(__task_cred(p)->user_ns, CAP_SYS_NICE)) {
4720			rcu_read_unlock();
4721			goto out_free_new_mask;
4722		}
4723		rcu_read_unlock();
4724	}
4725
4726	retval = security_task_setscheduler(p);
4727	if (retval)
4728		goto out_free_new_mask;
4729
4730
4731	cpuset_cpus_allowed(p, cpus_allowed);
4732	cpumask_and(new_mask, in_mask, cpus_allowed);
4733
4734	/*
4735	 * Since bandwidth control happens on root_domain basis,
4736	 * if admission test is enabled, we only admit -deadline
4737	 * tasks allowed to run on all the CPUs in the task's
4738	 * root_domain.
4739	 */
4740#ifdef CONFIG_SMP
4741	if (task_has_dl_policy(p) && dl_bandwidth_enabled()) {
4742		rcu_read_lock();
4743		if (!cpumask_subset(task_rq(p)->rd->span, new_mask)) {
4744			retval = -EBUSY;
4745			rcu_read_unlock();
4746			goto out_free_new_mask;
4747		}
4748		rcu_read_unlock();
4749	}
4750#endif
4751again:
4752	retval = __set_cpus_allowed_ptr(p, new_mask, true);
4753
4754	if (!retval) {
4755		cpuset_cpus_allowed(p, cpus_allowed);
4756		if (!cpumask_subset(new_mask, cpus_allowed)) {
4757			/*
4758			 * We must have raced with a concurrent cpuset
4759			 * update. Just reset the cpus_allowed to the
4760			 * cpuset's cpus_allowed
4761			 */
4762			cpumask_copy(new_mask, cpus_allowed);
4763			goto again;
4764		}
4765	}
4766out_free_new_mask:
4767	free_cpumask_var(new_mask);
4768out_free_cpus_allowed:
4769	free_cpumask_var(cpus_allowed);
4770out_put_task:
4771	put_task_struct(p);
4772	return retval;
4773}
4774
4775static int get_user_cpu_mask(unsigned long __user *user_mask_ptr, unsigned len,
4776			     struct cpumask *new_mask)
4777{
4778	if (len < cpumask_size())
4779		cpumask_clear(new_mask);
4780	else if (len > cpumask_size())
4781		len = cpumask_size();
4782
4783	return copy_from_user(new_mask, user_mask_ptr, len) ? -EFAULT : 0;
4784}
4785
4786/**
4787 * sys_sched_setaffinity - set the cpu affinity of a process
4788 * @pid: pid of the process
4789 * @len: length in bytes of the bitmask pointed to by user_mask_ptr
4790 * @user_mask_ptr: user-space pointer to the new cpu mask
4791 *
4792 * Return: 0 on success. An error code otherwise.
4793 */
4794SYSCALL_DEFINE3(sched_setaffinity, pid_t, pid, unsigned int, len,
4795		unsigned long __user *, user_mask_ptr)
4796{
4797	cpumask_var_t new_mask;
4798	int retval;
4799
4800	if (!alloc_cpumask_var(&new_mask, GFP_KERNEL))
4801		return -ENOMEM;
4802
4803	retval = get_user_cpu_mask(user_mask_ptr, len, new_mask);
4804	if (retval == 0)
4805		retval = sched_setaffinity(pid, new_mask);
4806	free_cpumask_var(new_mask);
4807	return retval;
4808}
4809
4810long sched_getaffinity(pid_t pid, struct cpumask *mask)
4811{
4812	struct task_struct *p;
4813	unsigned long flags;
4814	int retval;
4815
4816	rcu_read_lock();
4817
4818	retval = -ESRCH;
4819	p = find_process_by_pid(pid);
4820	if (!p)
4821		goto out_unlock;
4822
4823	retval = security_task_getscheduler(p);
4824	if (retval)
4825		goto out_unlock;
4826
4827	raw_spin_lock_irqsave(&p->pi_lock, flags);
4828	cpumask_and(mask, &p->cpus_allowed, cpu_active_mask);
4829	raw_spin_unlock_irqrestore(&p->pi_lock, flags);
4830
4831out_unlock:
4832	rcu_read_unlock();
4833
4834	return retval;
4835}
4836
4837/**
4838 * sys_sched_getaffinity - get the cpu affinity of a process
4839 * @pid: pid of the process
4840 * @len: length in bytes of the bitmask pointed to by user_mask_ptr
4841 * @user_mask_ptr: user-space pointer to hold the current cpu mask
4842 *
4843 * Return: size of CPU mask copied to user_mask_ptr on success. An
4844 * error code otherwise.
4845 */
4846SYSCALL_DEFINE3(sched_getaffinity, pid_t, pid, unsigned int, len,
4847		unsigned long __user *, user_mask_ptr)
4848{
4849	int ret;
4850	cpumask_var_t mask;
4851
4852	if ((len * BITS_PER_BYTE) < nr_cpu_ids)
4853		return -EINVAL;
4854	if (len & (sizeof(unsigned long)-1))
4855		return -EINVAL;
4856
4857	if (!alloc_cpumask_var(&mask, GFP_KERNEL))
4858		return -ENOMEM;
4859
4860	ret = sched_getaffinity(pid, mask);
4861	if (ret == 0) {
4862		size_t retlen = min_t(size_t, len, cpumask_size());
4863
4864		if (copy_to_user(user_mask_ptr, mask, retlen))
4865			ret = -EFAULT;
4866		else
4867			ret = retlen;
4868	}
4869	free_cpumask_var(mask);
4870
4871	return ret;
4872}
4873
4874/**
4875 * sys_sched_yield - yield the current processor to other threads.
4876 *
4877 * This function yields the current CPU to other tasks. If there are no
4878 * other threads running on this CPU then this function will return.
4879 *
4880 * Return: 0.
4881 */
4882SYSCALL_DEFINE0(sched_yield)
4883{
4884	struct rq *rq = this_rq_lock();
 
 
 
 
 
4885
4886	schedstat_inc(rq->yld_count);
4887	current->sched_class->yield_task(rq);
4888
4889	/*
4890	 * Since we are going to call schedule() anyway, there's
4891	 * no need to preempt or enable interrupts:
4892	 */
4893	__release(rq->lock);
4894	spin_release(&rq->lock.dep_map, 1, _THIS_IP_);
4895	do_raw_spin_unlock(&rq->lock);
4896	sched_preempt_enable_no_resched();
4897
4898	schedule();
 
4899
 
 
 
4900	return 0;
4901}
4902
4903#ifndef CONFIG_PREEMPT
4904int __sched _cond_resched(void)
4905{
4906	if (should_resched(0)) {
4907		preempt_schedule_common();
4908		return 1;
4909	}
 
4910	return 0;
4911}
4912EXPORT_SYMBOL(_cond_resched);
4913#endif
4914
4915/*
4916 * __cond_resched_lock() - if a reschedule is pending, drop the given lock,
4917 * call schedule, and on return reacquire the lock.
4918 *
4919 * This works OK both with and without CONFIG_PREEMPT. We do strange low-level
4920 * operations here to prevent schedule() from being called twice (once via
4921 * spin_unlock(), once by hand).
4922 */
4923int __cond_resched_lock(spinlock_t *lock)
4924{
4925	int resched = should_resched(PREEMPT_LOCK_OFFSET);
4926	int ret = 0;
4927
4928	lockdep_assert_held(lock);
4929
4930	if (spin_needbreak(lock) || resched) {
4931		spin_unlock(lock);
4932		if (resched)
4933			preempt_schedule_common();
4934		else
4935			cpu_relax();
4936		ret = 1;
4937		spin_lock(lock);
4938	}
4939	return ret;
4940}
4941EXPORT_SYMBOL(__cond_resched_lock);
4942
4943int __sched __cond_resched_softirq(void)
4944{
4945	BUG_ON(!in_softirq());
4946
4947	if (should_resched(SOFTIRQ_DISABLE_OFFSET)) {
4948		local_bh_enable();
4949		preempt_schedule_common();
4950		local_bh_disable();
4951		return 1;
4952	}
4953	return 0;
4954}
4955EXPORT_SYMBOL(__cond_resched_softirq);
4956
4957/**
4958 * yield - yield the current processor to other threads.
4959 *
4960 * Do not ever use this function, there's a 99% chance you're doing it wrong.
4961 *
4962 * The scheduler is at all times free to pick the calling task as the most
4963 * eligible task to run, if removing the yield() call from your code breaks
4964 * it, its already broken.
4965 *
4966 * Typical broken usage is:
4967 *
4968 * while (!event)
4969 * 	yield();
4970 *
4971 * where one assumes that yield() will let 'the other' process run that will
4972 * make event true. If the current task is a SCHED_FIFO task that will never
4973 * happen. Never use yield() as a progress guarantee!!
4974 *
4975 * If you want to use yield() to wait for something, use wait_event().
4976 * If you want to use yield() to be 'nice' for others, use cond_resched().
4977 * If you still want to use yield(), do not!
4978 */
4979void __sched yield(void)
4980{
4981	set_current_state(TASK_RUNNING);
4982	sys_sched_yield();
4983}
4984EXPORT_SYMBOL(yield);
4985
4986/**
4987 * yield_to - yield the current processor to another thread in
4988 * your thread group, or accelerate that thread toward the
4989 * processor it's on.
4990 * @p: target task
4991 * @preempt: whether task preemption is allowed or not
4992 *
4993 * It's the caller's job to ensure that the target task struct
4994 * can't go away on us before we can do any checks.
4995 *
4996 * Return:
4997 *	true (>0) if we indeed boosted the target task.
4998 *	false (0) if we failed to boost the target.
4999 *	-ESRCH if there's no task to yield to.
5000 */
5001int __sched yield_to(struct task_struct *p, bool preempt)
5002{
5003	struct task_struct *curr = current;
5004	struct rq *rq, *p_rq;
5005	unsigned long flags;
5006	int yielded = 0;
5007
5008	local_irq_save(flags);
5009	rq = this_rq();
5010
5011again:
5012	p_rq = task_rq(p);
5013	/*
5014	 * If we're the only runnable task on the rq and target rq also
5015	 * has only one task, there's absolutely no point in yielding.
5016	 */
5017	if (rq->nr_running == 1 && p_rq->nr_running == 1) {
5018		yielded = -ESRCH;
5019		goto out_irq;
5020	}
5021
5022	double_rq_lock(rq, p_rq);
5023	if (task_rq(p) != p_rq) {
5024		double_rq_unlock(rq, p_rq);
5025		goto again;
5026	}
5027
5028	if (!curr->sched_class->yield_to_task)
5029		goto out_unlock;
5030
5031	if (curr->sched_class != p->sched_class)
5032		goto out_unlock;
5033
5034	if (task_running(p_rq, p) || p->state)
5035		goto out_unlock;
5036
5037	yielded = curr->sched_class->yield_to_task(rq, p, preempt);
5038	if (yielded) {
5039		schedstat_inc(rq->yld_count);
5040		/*
5041		 * Make p's CPU reschedule; pick_next_entity takes care of
5042		 * fairness.
5043		 */
5044		if (preempt && rq != p_rq)
5045			resched_curr(p_rq);
5046	}
5047
5048out_unlock:
5049	double_rq_unlock(rq, p_rq);
5050out_irq:
5051	local_irq_restore(flags);
5052
5053	if (yielded > 0)
5054		schedule();
5055
5056	return yielded;
5057}
5058EXPORT_SYMBOL_GPL(yield_to);
5059
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
5060/*
5061 * This task is about to go to sleep on IO. Increment rq->nr_iowait so
5062 * that process accounting knows that this is a task in IO wait state.
5063 */
5064long __sched io_schedule_timeout(long timeout)
5065{
5066	int old_iowait = current->in_iowait;
5067	struct rq *rq;
5068	long ret;
5069
5070	current->in_iowait = 1;
5071	blk_schedule_flush_plug(current);
5072
5073	delayacct_blkio_start();
5074	rq = raw_rq();
5075	atomic_inc(&rq->nr_iowait);
5076	ret = schedule_timeout(timeout);
5077	current->in_iowait = old_iowait;
5078	atomic_dec(&rq->nr_iowait);
5079	delayacct_blkio_end();
5080
5081	return ret;
5082}
5083EXPORT_SYMBOL(io_schedule_timeout);
5084
 
 
 
 
 
 
 
 
 
 
5085/**
5086 * sys_sched_get_priority_max - return maximum RT priority.
5087 * @policy: scheduling class.
5088 *
5089 * Return: On success, this syscall returns the maximum
5090 * rt_priority that can be used by a given scheduling class.
5091 * On failure, a negative error code is returned.
5092 */
5093SYSCALL_DEFINE1(sched_get_priority_max, int, policy)
5094{
5095	int ret = -EINVAL;
5096
5097	switch (policy) {
5098	case SCHED_FIFO:
5099	case SCHED_RR:
5100		ret = MAX_USER_RT_PRIO-1;
5101		break;
5102	case SCHED_DEADLINE:
5103	case SCHED_NORMAL:
5104	case SCHED_BATCH:
5105	case SCHED_IDLE:
5106		ret = 0;
5107		break;
5108	}
5109	return ret;
5110}
5111
5112/**
5113 * sys_sched_get_priority_min - return minimum RT priority.
5114 * @policy: scheduling class.
5115 *
5116 * Return: On success, this syscall returns the minimum
5117 * rt_priority that can be used by a given scheduling class.
5118 * On failure, a negative error code is returned.
5119 */
5120SYSCALL_DEFINE1(sched_get_priority_min, int, policy)
5121{
5122	int ret = -EINVAL;
5123
5124	switch (policy) {
5125	case SCHED_FIFO:
5126	case SCHED_RR:
5127		ret = 1;
5128		break;
5129	case SCHED_DEADLINE:
5130	case SCHED_NORMAL:
5131	case SCHED_BATCH:
5132	case SCHED_IDLE:
5133		ret = 0;
5134	}
5135	return ret;
5136}
5137
5138/**
5139 * sys_sched_rr_get_interval - return the default timeslice of a process.
5140 * @pid: pid of the process.
5141 * @interval: userspace pointer to the timeslice value.
5142 *
5143 * this syscall writes the default timeslice value of a given process
5144 * into the user-space timespec buffer. A value of '0' means infinity.
5145 *
5146 * Return: On success, 0 and the timeslice is in @interval. Otherwise,
5147 * an error code.
5148 */
5149SYSCALL_DEFINE2(sched_rr_get_interval, pid_t, pid,
5150		struct timespec __user *, interval)
5151{
5152	struct task_struct *p;
5153	unsigned int time_slice;
5154	struct rq_flags rf;
5155	struct timespec t;
5156	struct rq *rq;
5157	int retval;
5158
5159	if (pid < 0)
5160		return -EINVAL;
5161
5162	retval = -ESRCH;
5163	rcu_read_lock();
5164	p = find_process_by_pid(pid);
5165	if (!p)
5166		goto out_unlock;
5167
5168	retval = security_task_getscheduler(p);
5169	if (retval)
5170		goto out_unlock;
5171
5172	rq = task_rq_lock(p, &rf);
5173	time_slice = 0;
5174	if (p->sched_class->get_rr_interval)
5175		time_slice = p->sched_class->get_rr_interval(rq, p);
5176	task_rq_unlock(rq, p, &rf);
5177
5178	rcu_read_unlock();
5179	jiffies_to_timespec(time_slice, &t);
5180	retval = copy_to_user(interval, &t, sizeof(t)) ? -EFAULT : 0;
5181	return retval;
5182
5183out_unlock:
5184	rcu_read_unlock();
5185	return retval;
5186}
5187
5188static const char stat_nam[] = TASK_STATE_TO_CHAR_STR;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
5189
5190void sched_show_task(struct task_struct *p)
5191{
5192	unsigned long free = 0;
5193	int ppid;
5194	unsigned long state = p->state;
5195
5196	if (!try_get_task_stack(p))
5197		return;
5198	if (state)
5199		state = __ffs(state) + 1;
5200	printk(KERN_INFO "%-15.15s %c", p->comm,
5201		state < sizeof(stat_nam) - 1 ? stat_nam[state] : '?');
5202	if (state == TASK_RUNNING)
5203		printk(KERN_CONT "  running task    ");
5204#ifdef CONFIG_DEBUG_STACK_USAGE
5205	free = stack_not_used(p);
5206#endif
5207	ppid = 0;
5208	rcu_read_lock();
5209	if (pid_alive(p))
5210		ppid = task_pid_nr(rcu_dereference(p->real_parent));
5211	rcu_read_unlock();
5212	printk(KERN_CONT "%5lu %5d %6d 0x%08lx\n", free,
5213		task_pid_nr(p), ppid,
5214		(unsigned long)task_thread_info(p)->flags);
5215
5216	print_worker_info(KERN_INFO, p);
5217	show_stack(p, NULL);
5218	put_task_stack(p);
5219}
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
5220
5221void show_state_filter(unsigned long state_filter)
5222{
5223	struct task_struct *g, *p;
5224
5225#if BITS_PER_LONG == 32
5226	printk(KERN_INFO
5227		"  task                PC stack   pid father\n");
5228#else
5229	printk(KERN_INFO
5230		"  task                        PC stack   pid father\n");
5231#endif
5232	rcu_read_lock();
5233	for_each_process_thread(g, p) {
5234		/*
5235		 * reset the NMI-timeout, listing all files on a slow
5236		 * console might take a lot of time:
5237		 * Also, reset softlockup watchdogs on all CPUs, because
5238		 * another CPU might be blocked waiting for us to process
5239		 * an IPI.
5240		 */
5241		touch_nmi_watchdog();
5242		touch_all_softlockup_watchdogs();
5243		if (!state_filter || (p->state & state_filter))
5244			sched_show_task(p);
5245	}
5246
5247#ifdef CONFIG_SCHED_DEBUG
5248	if (!state_filter)
5249		sysrq_sched_debug_show();
5250#endif
5251	rcu_read_unlock();
5252	/*
5253	 * Only show locks if all tasks are dumped:
5254	 */
5255	if (!state_filter)
5256		debug_show_all_locks();
5257}
5258
5259void init_idle_bootup_task(struct task_struct *idle)
5260{
5261	idle->sched_class = &idle_sched_class;
5262}
5263
5264/**
5265 * init_idle - set up an idle thread for a given CPU
5266 * @idle: task in question
5267 * @cpu: cpu the idle task belongs to
5268 *
5269 * NOTE: this function does not set the idle thread's NEED_RESCHED
5270 * flag, to make booting more robust.
5271 */
5272void init_idle(struct task_struct *idle, int cpu)
5273{
5274	struct rq *rq = cpu_rq(cpu);
5275	unsigned long flags;
5276
5277	raw_spin_lock_irqsave(&idle->pi_lock, flags);
5278	raw_spin_lock(&rq->lock);
5279
5280	__sched_fork(0, idle);
5281	idle->state = TASK_RUNNING;
5282	idle->se.exec_start = sched_clock();
5283	idle->flags |= PF_IDLE;
5284
5285	kasan_unpoison_task_stack(idle);
5286
5287#ifdef CONFIG_SMP
5288	/*
5289	 * Its possible that init_idle() gets called multiple times on a task,
5290	 * in that case do_set_cpus_allowed() will not do the right thing.
5291	 *
5292	 * And since this is boot we can forgo the serialization.
5293	 */
5294	set_cpus_allowed_common(idle, cpumask_of(cpu));
5295#endif
5296	/*
5297	 * We're having a chicken and egg problem, even though we are
5298	 * holding rq->lock, the cpu isn't yet set to this cpu so the
5299	 * lockdep check in task_group() will fail.
5300	 *
5301	 * Similar case to sched_fork(). / Alternatively we could
5302	 * use task_rq_lock() here and obtain the other rq->lock.
5303	 *
5304	 * Silence PROVE_RCU
5305	 */
5306	rcu_read_lock();
5307	__set_task_cpu(idle, cpu);
5308	rcu_read_unlock();
5309
5310	rq->curr = rq->idle = idle;
5311	idle->on_rq = TASK_ON_RQ_QUEUED;
5312#ifdef CONFIG_SMP
5313	idle->on_cpu = 1;
5314#endif
5315	raw_spin_unlock(&rq->lock);
5316	raw_spin_unlock_irqrestore(&idle->pi_lock, flags);
5317
5318	/* Set the preempt count _outside_ the spinlocks! */
5319	init_idle_preempt_count(idle, cpu);
5320
5321	/*
5322	 * The idle tasks have their own, simple scheduling class:
5323	 */
5324	idle->sched_class = &idle_sched_class;
5325	ftrace_graph_init_idle_task(idle, cpu);
5326	vtime_init_idle(idle, cpu);
5327#ifdef CONFIG_SMP
5328	sprintf(idle->comm, "%s/%d", INIT_TASK_COMM, cpu);
5329#endif
5330}
5331
 
 
5332int cpuset_cpumask_can_shrink(const struct cpumask *cur,
5333			      const struct cpumask *trial)
5334{
5335	int ret = 1, trial_cpus;
5336	struct dl_bw *cur_dl_b;
5337	unsigned long flags;
5338
5339	if (!cpumask_weight(cur))
5340		return ret;
5341
5342	rcu_read_lock_sched();
5343	cur_dl_b = dl_bw_of(cpumask_any(cur));
5344	trial_cpus = cpumask_weight(trial);
5345
5346	raw_spin_lock_irqsave(&cur_dl_b->lock, flags);
5347	if (cur_dl_b->bw != -1 &&
5348	    cur_dl_b->bw * trial_cpus < cur_dl_b->total_bw)
5349		ret = 0;
5350	raw_spin_unlock_irqrestore(&cur_dl_b->lock, flags);
5351	rcu_read_unlock_sched();
5352
5353	return ret;
5354}
5355
5356int task_can_attach(struct task_struct *p,
5357		    const struct cpumask *cs_cpus_allowed)
5358{
5359	int ret = 0;
5360
5361	/*
5362	 * Kthreads which disallow setaffinity shouldn't be moved
5363	 * to a new cpuset; we don't want to change their cpu
5364	 * affinity and isolating such threads by their set of
5365	 * allowed nodes is unnecessary.  Thus, cpusets are not
5366	 * applicable for such threads.  This prevents checking for
5367	 * success of set_cpus_allowed_ptr() on all attached tasks
5368	 * before cpus_allowed may be changed.
5369	 */
5370	if (p->flags & PF_NO_SETAFFINITY) {
5371		ret = -EINVAL;
5372		goto out;
5373	}
5374
5375#ifdef CONFIG_SMP
5376	if (dl_task(p) && !cpumask_intersects(task_rq(p)->rd->span,
5377					      cs_cpus_allowed)) {
5378		unsigned int dest_cpu = cpumask_any_and(cpu_active_mask,
5379							cs_cpus_allowed);
5380		struct dl_bw *dl_b;
5381		bool overflow;
5382		int cpus;
5383		unsigned long flags;
5384
5385		rcu_read_lock_sched();
5386		dl_b = dl_bw_of(dest_cpu);
5387		raw_spin_lock_irqsave(&dl_b->lock, flags);
5388		cpus = dl_bw_cpus(dest_cpu);
5389		overflow = __dl_overflow(dl_b, cpus, 0, p->dl.dl_bw);
5390		if (overflow)
5391			ret = -EBUSY;
5392		else {
5393			/*
5394			 * We reserve space for this task in the destination
5395			 * root_domain, as we can't fail after this point.
5396			 * We will free resources in the source root_domain
5397			 * later on (see set_cpus_allowed_dl()).
5398			 */
5399			__dl_add(dl_b, p->dl.dl_bw);
5400		}
5401		raw_spin_unlock_irqrestore(&dl_b->lock, flags);
5402		rcu_read_unlock_sched();
5403
5404	}
5405#endif
5406out:
5407	return ret;
5408}
5409
5410#ifdef CONFIG_SMP
5411
5412static bool sched_smp_initialized __read_mostly;
5413
5414#ifdef CONFIG_NUMA_BALANCING
5415/* Migrate current task p to target_cpu */
5416int migrate_task_to(struct task_struct *p, int target_cpu)
5417{
5418	struct migration_arg arg = { p, target_cpu };
5419	int curr_cpu = task_cpu(p);
5420
5421	if (curr_cpu == target_cpu)
5422		return 0;
5423
5424	if (!cpumask_test_cpu(target_cpu, tsk_cpus_allowed(p)))
5425		return -EINVAL;
5426
5427	/* TODO: This is not properly updating schedstats */
5428
5429	trace_sched_move_numa(p, curr_cpu, target_cpu);
5430	return stop_one_cpu(curr_cpu, migration_cpu_stop, &arg);
5431}
5432
5433/*
5434 * Requeue a task on a given node and accurately track the number of NUMA
5435 * tasks on the runqueues
5436 */
5437void sched_setnuma(struct task_struct *p, int nid)
5438{
5439	bool queued, running;
5440	struct rq_flags rf;
5441	struct rq *rq;
5442
5443	rq = task_rq_lock(p, &rf);
5444	queued = task_on_rq_queued(p);
5445	running = task_current(rq, p);
5446
5447	if (queued)
5448		dequeue_task(rq, p, DEQUEUE_SAVE);
5449	if (running)
5450		put_prev_task(rq, p);
5451
5452	p->numa_preferred_nid = nid;
5453
5454	if (queued)
5455		enqueue_task(rq, p, ENQUEUE_RESTORE);
5456	if (running)
5457		set_curr_task(rq, p);
5458	task_rq_unlock(rq, p, &rf);
5459}
5460#endif /* CONFIG_NUMA_BALANCING */
5461
5462#ifdef CONFIG_HOTPLUG_CPU
5463/*
5464 * Ensures that the idle task is using init_mm right before its cpu goes
5465 * offline.
5466 */
5467void idle_task_exit(void)
5468{
5469	struct mm_struct *mm = current->active_mm;
5470
5471	BUG_ON(cpu_online(smp_processor_id()));
5472
5473	if (mm != &init_mm) {
5474		switch_mm_irqs_off(mm, &init_mm, current);
 
5475		finish_arch_post_lock_switch();
5476	}
5477	mmdrop(mm);
5478}
5479
5480/*
5481 * Since this CPU is going 'away' for a while, fold any nr_active delta
5482 * we might have. Assumes we're called after migrate_tasks() so that the
5483 * nr_active count is stable. We need to take the teardown thread which
5484 * is calling this into account, so we hand in adjust = 1 to the load
5485 * calculation.
5486 *
5487 * Also see the comment "Global load-average calculations".
5488 */
5489static void calc_load_migrate(struct rq *rq)
5490{
5491	long delta = calc_load_fold_active(rq, 1);
5492	if (delta)
5493		atomic_long_add(delta, &calc_load_tasks);
5494}
5495
5496static void put_prev_task_fake(struct rq *rq, struct task_struct *prev)
5497{
5498}
5499
5500static const struct sched_class fake_sched_class = {
5501	.put_prev_task = put_prev_task_fake,
5502};
5503
5504static struct task_struct fake_task = {
5505	/*
5506	 * Avoid pull_{rt,dl}_task()
5507	 */
5508	.prio = MAX_PRIO + 1,
5509	.sched_class = &fake_sched_class,
5510};
5511
5512/*
5513 * Migrate all tasks from the rq, sleeping tasks will be migrated by
5514 * try_to_wake_up()->select_task_rq().
5515 *
5516 * Called with rq->lock held even though we'er in stop_machine() and
5517 * there's no concurrency possible, we hold the required locks anyway
5518 * because of lock validation efforts.
5519 */
5520static void migrate_tasks(struct rq *dead_rq)
5521{
5522	struct rq *rq = dead_rq;
5523	struct task_struct *next, *stop = rq->stop;
5524	struct pin_cookie cookie;
5525	int dest_cpu;
5526
5527	/*
5528	 * Fudge the rq selection such that the below task selection loop
5529	 * doesn't get stuck on the currently eligible stop task.
5530	 *
5531	 * We're currently inside stop_machine() and the rq is either stuck
5532	 * in the stop_machine_cpu_stop() loop, or we're executing this code,
5533	 * either way we should never end up calling schedule() until we're
5534	 * done here.
5535	 */
5536	rq->stop = NULL;
5537
5538	/*
5539	 * put_prev_task() and pick_next_task() sched
5540	 * class method both need to have an up-to-date
5541	 * value of rq->clock[_task]
5542	 */
5543	update_rq_clock(rq);
5544
5545	for (;;) {
5546		/*
5547		 * There's this thread running, bail when that's the only
5548		 * remaining thread.
5549		 */
5550		if (rq->nr_running == 1)
5551			break;
5552
5553		/*
5554		 * pick_next_task assumes pinned rq->lock.
5555		 */
5556		cookie = lockdep_pin_lock(&rq->lock);
5557		next = pick_next_task(rq, &fake_task, cookie);
5558		BUG_ON(!next);
5559		next->sched_class->put_prev_task(rq, next);
5560
5561		/*
5562		 * Rules for changing task_struct::cpus_allowed are holding
5563		 * both pi_lock and rq->lock, such that holding either
5564		 * stabilizes the mask.
5565		 *
5566		 * Drop rq->lock is not quite as disastrous as it usually is
5567		 * because !cpu_active at this point, which means load-balance
5568		 * will not interfere. Also, stop-machine.
5569		 */
5570		lockdep_unpin_lock(&rq->lock, cookie);
5571		raw_spin_unlock(&rq->lock);
5572		raw_spin_lock(&next->pi_lock);
5573		raw_spin_lock(&rq->lock);
5574
5575		/*
5576		 * Since we're inside stop-machine, _nothing_ should have
5577		 * changed the task, WARN if weird stuff happened, because in
5578		 * that case the above rq->lock drop is a fail too.
5579		 */
5580		if (WARN_ON(task_rq(next) != rq || !task_on_rq_queued(next))) {
5581			raw_spin_unlock(&next->pi_lock);
5582			continue;
5583		}
5584
5585		/* Find suitable destination for @next, with force if needed. */
5586		dest_cpu = select_fallback_rq(dead_rq->cpu, next);
5587
5588		rq = __migrate_task(rq, next, dest_cpu);
5589		if (rq != dead_rq) {
5590			raw_spin_unlock(&rq->lock);
5591			rq = dead_rq;
5592			raw_spin_lock(&rq->lock);
 
5593		}
5594		raw_spin_unlock(&next->pi_lock);
5595	}
5596
5597	rq->stop = stop;
5598}
5599#endif /* CONFIG_HOTPLUG_CPU */
5600
5601static void set_rq_online(struct rq *rq)
5602{
5603	if (!rq->online) {
5604		const struct sched_class *class;
5605
5606		cpumask_set_cpu(rq->cpu, rq->rd->online);
5607		rq->online = 1;
5608
5609		for_each_class(class) {
5610			if (class->rq_online)
5611				class->rq_online(rq);
5612		}
5613	}
5614}
5615
5616static void set_rq_offline(struct rq *rq)
5617{
5618	if (rq->online) {
5619		const struct sched_class *class;
5620
5621		for_each_class(class) {
5622			if (class->rq_offline)
5623				class->rq_offline(rq);
5624		}
5625
5626		cpumask_clear_cpu(rq->cpu, rq->rd->online);
5627		rq->online = 0;
5628	}
5629}
5630
5631static void set_cpu_rq_start_time(unsigned int cpu)
5632{
5633	struct rq *rq = cpu_rq(cpu);
5634
5635	rq->age_stamp = sched_clock_cpu(cpu);
5636}
5637
5638static cpumask_var_t sched_domains_tmpmask; /* sched_domains_mutex */
5639
5640#ifdef CONFIG_SCHED_DEBUG
5641
5642static __read_mostly int sched_debug_enabled;
5643
5644static int __init sched_debug_setup(char *str)
5645{
5646	sched_debug_enabled = 1;
5647
5648	return 0;
5649}
5650early_param("sched_debug", sched_debug_setup);
5651
5652static inline bool sched_debug(void)
5653{
5654	return sched_debug_enabled;
5655}
5656
5657static int sched_domain_debug_one(struct sched_domain *sd, int cpu, int level,
5658				  struct cpumask *groupmask)
5659{
5660	struct sched_group *group = sd->groups;
5661
5662	cpumask_clear(groupmask);
5663
5664	printk(KERN_DEBUG "%*s domain %d: ", level, "", level);
5665
5666	if (!(sd->flags & SD_LOAD_BALANCE)) {
5667		printk("does not load-balance\n");
5668		if (sd->parent)
5669			printk(KERN_ERR "ERROR: !SD_LOAD_BALANCE domain"
5670					" has parent");
5671		return -1;
5672	}
5673
5674	printk(KERN_CONT "span %*pbl level %s\n",
5675	       cpumask_pr_args(sched_domain_span(sd)), sd->name);
5676
5677	if (!cpumask_test_cpu(cpu, sched_domain_span(sd))) {
5678		printk(KERN_ERR "ERROR: domain->span does not contain "
5679				"CPU%d\n", cpu);
5680	}
5681	if (!cpumask_test_cpu(cpu, sched_group_cpus(group))) {
5682		printk(KERN_ERR "ERROR: domain->groups does not contain"
5683				" CPU%d\n", cpu);
5684	}
5685
5686	printk(KERN_DEBUG "%*s groups:", level + 1, "");
5687	do {
5688		if (!group) {
5689			printk("\n");
5690			printk(KERN_ERR "ERROR: group is NULL\n");
5691			break;
5692		}
5693
5694		if (!cpumask_weight(sched_group_cpus(group))) {
5695			printk(KERN_CONT "\n");
5696			printk(KERN_ERR "ERROR: empty group\n");
5697			break;
5698		}
5699
5700		if (!(sd->flags & SD_OVERLAP) &&
5701		    cpumask_intersects(groupmask, sched_group_cpus(group))) {
5702			printk(KERN_CONT "\n");
5703			printk(KERN_ERR "ERROR: repeated CPUs\n");
5704			break;
5705		}
5706
5707		cpumask_or(groupmask, groupmask, sched_group_cpus(group));
5708
5709		printk(KERN_CONT " %*pbl",
5710		       cpumask_pr_args(sched_group_cpus(group)));
5711		if (group->sgc->capacity != SCHED_CAPACITY_SCALE) {
5712			printk(KERN_CONT " (cpu_capacity = %lu)",
5713				group->sgc->capacity);
5714		}
5715
5716		group = group->next;
5717	} while (group != sd->groups);
5718	printk(KERN_CONT "\n");
5719
5720	if (!cpumask_equal(sched_domain_span(sd), groupmask))
5721		printk(KERN_ERR "ERROR: groups don't span domain->span\n");
5722
5723	if (sd->parent &&
5724	    !cpumask_subset(groupmask, sched_domain_span(sd->parent)))
5725		printk(KERN_ERR "ERROR: parent span is not a superset "
5726			"of domain->span\n");
5727	return 0;
5728}
5729
5730static void sched_domain_debug(struct sched_domain *sd, int cpu)
5731{
5732	int level = 0;
5733
5734	if (!sched_debug_enabled)
5735		return;
5736
5737	if (!sd) {
5738		printk(KERN_DEBUG "CPU%d attaching NULL sched-domain.\n", cpu);
5739		return;
5740	}
5741
5742	printk(KERN_DEBUG "CPU%d attaching sched-domain:\n", cpu);
5743
5744	for (;;) {
5745		if (sched_domain_debug_one(sd, cpu, level, sched_domains_tmpmask))
5746			break;
5747		level++;
5748		sd = sd->parent;
5749		if (!sd)
5750			break;
5751	}
5752}
5753#else /* !CONFIG_SCHED_DEBUG */
5754
5755# define sched_debug_enabled 0
5756# define sched_domain_debug(sd, cpu) do { } while (0)
5757static inline bool sched_debug(void)
5758{
5759	return false;
5760}
5761#endif /* CONFIG_SCHED_DEBUG */
5762
5763static int sd_degenerate(struct sched_domain *sd)
5764{
5765	if (cpumask_weight(sched_domain_span(sd)) == 1)
5766		return 1;
5767
5768	/* Following flags need at least 2 groups */
5769	if (sd->flags & (SD_LOAD_BALANCE |
5770			 SD_BALANCE_NEWIDLE |
5771			 SD_BALANCE_FORK |
5772			 SD_BALANCE_EXEC |
5773			 SD_SHARE_CPUCAPACITY |
5774			 SD_ASYM_CPUCAPACITY |
5775			 SD_SHARE_PKG_RESOURCES |
5776			 SD_SHARE_POWERDOMAIN)) {
5777		if (sd->groups != sd->groups->next)
5778			return 0;
5779	}
5780
5781	/* Following flags don't use groups */
5782	if (sd->flags & (SD_WAKE_AFFINE))
5783		return 0;
5784
5785	return 1;
5786}
5787
5788static int
5789sd_parent_degenerate(struct sched_domain *sd, struct sched_domain *parent)
5790{
5791	unsigned long cflags = sd->flags, pflags = parent->flags;
5792
5793	if (sd_degenerate(parent))
5794		return 1;
5795
5796	if (!cpumask_equal(sched_domain_span(sd), sched_domain_span(parent)))
5797		return 0;
5798
5799	/* Flags needing groups don't count if only 1 group in parent */
5800	if (parent->groups == parent->groups->next) {
5801		pflags &= ~(SD_LOAD_BALANCE |
5802				SD_BALANCE_NEWIDLE |
5803				SD_BALANCE_FORK |
5804				SD_BALANCE_EXEC |
5805				SD_ASYM_CPUCAPACITY |
5806				SD_SHARE_CPUCAPACITY |
5807				SD_SHARE_PKG_RESOURCES |
5808				SD_PREFER_SIBLING |
5809				SD_SHARE_POWERDOMAIN);
5810		if (nr_node_ids == 1)
5811			pflags &= ~SD_SERIALIZE;
5812	}
5813	if (~cflags & pflags)
5814		return 0;
5815
5816	return 1;
5817}
5818
5819static void free_rootdomain(struct rcu_head *rcu)
5820{
5821	struct root_domain *rd = container_of(rcu, struct root_domain, rcu);
5822
5823	cpupri_cleanup(&rd->cpupri);
5824	cpudl_cleanup(&rd->cpudl);
5825	free_cpumask_var(rd->dlo_mask);
5826	free_cpumask_var(rd->rto_mask);
5827	free_cpumask_var(rd->online);
5828	free_cpumask_var(rd->span);
5829	kfree(rd);
5830}
5831
5832static void rq_attach_root(struct rq *rq, struct root_domain *rd)
5833{
5834	struct root_domain *old_rd = NULL;
5835	unsigned long flags;
5836
5837	raw_spin_lock_irqsave(&rq->lock, flags);
5838
5839	if (rq->rd) {
5840		old_rd = rq->rd;
5841
5842		if (cpumask_test_cpu(rq->cpu, old_rd->online))
5843			set_rq_offline(rq);
5844
5845		cpumask_clear_cpu(rq->cpu, old_rd->span);
5846
5847		/*
5848		 * If we dont want to free the old_rd yet then
5849		 * set old_rd to NULL to skip the freeing later
5850		 * in this function:
5851		 */
5852		if (!atomic_dec_and_test(&old_rd->refcount))
5853			old_rd = NULL;
5854	}
5855
5856	atomic_inc(&rd->refcount);
5857	rq->rd = rd;
5858
5859	cpumask_set_cpu(rq->cpu, rd->span);
5860	if (cpumask_test_cpu(rq->cpu, cpu_active_mask))
5861		set_rq_online(rq);
5862
5863	raw_spin_unlock_irqrestore(&rq->lock, flags);
5864
5865	if (old_rd)
5866		call_rcu_sched(&old_rd->rcu, free_rootdomain);
5867}
5868
5869static int init_rootdomain(struct root_domain *rd)
5870{
5871	memset(rd, 0, sizeof(*rd));
5872
5873	if (!zalloc_cpumask_var(&rd->span, GFP_KERNEL))
5874		goto out;
5875	if (!zalloc_cpumask_var(&rd->online, GFP_KERNEL))
5876		goto free_span;
5877	if (!zalloc_cpumask_var(&rd->dlo_mask, GFP_KERNEL))
5878		goto free_online;
5879	if (!zalloc_cpumask_var(&rd->rto_mask, GFP_KERNEL))
5880		goto free_dlo_mask;
5881
5882	init_dl_bw(&rd->dl_bw);
5883	if (cpudl_init(&rd->cpudl) != 0)
5884		goto free_dlo_mask;
5885
5886	if (cpupri_init(&rd->cpupri) != 0)
5887		goto free_rto_mask;
5888	return 0;
5889
5890free_rto_mask:
5891	free_cpumask_var(rd->rto_mask);
5892free_dlo_mask:
5893	free_cpumask_var(rd->dlo_mask);
5894free_online:
5895	free_cpumask_var(rd->online);
5896free_span:
5897	free_cpumask_var(rd->span);
5898out:
5899	return -ENOMEM;
5900}
5901
5902/*
5903 * By default the system creates a single root-domain with all cpus as
5904 * members (mimicking the global state we have today).
5905 */
5906struct root_domain def_root_domain;
5907
5908static void init_defrootdomain(void)
5909{
5910	init_rootdomain(&def_root_domain);
5911
5912	atomic_set(&def_root_domain.refcount, 1);
5913}
5914
5915static struct root_domain *alloc_rootdomain(void)
5916{
5917	struct root_domain *rd;
5918
5919	rd = kmalloc(sizeof(*rd), GFP_KERNEL);
5920	if (!rd)
5921		return NULL;
5922
5923	if (init_rootdomain(rd) != 0) {
5924		kfree(rd);
5925		return NULL;
5926	}
5927
5928	return rd;
5929}
5930
5931static void free_sched_groups(struct sched_group *sg, int free_sgc)
5932{
5933	struct sched_group *tmp, *first;
5934
5935	if (!sg)
5936		return;
5937
5938	first = sg;
5939	do {
5940		tmp = sg->next;
5941
5942		if (free_sgc && atomic_dec_and_test(&sg->sgc->ref))
5943			kfree(sg->sgc);
5944
5945		kfree(sg);
5946		sg = tmp;
5947	} while (sg != first);
5948}
5949
5950static void destroy_sched_domain(struct sched_domain *sd)
5951{
5952	/*
5953	 * If its an overlapping domain it has private groups, iterate and
5954	 * nuke them all.
5955	 */
5956	if (sd->flags & SD_OVERLAP) {
5957		free_sched_groups(sd->groups, 1);
5958	} else if (atomic_dec_and_test(&sd->groups->ref)) {
5959		kfree(sd->groups->sgc);
5960		kfree(sd->groups);
5961	}
5962	if (sd->shared && atomic_dec_and_test(&sd->shared->ref))
5963		kfree(sd->shared);
5964	kfree(sd);
5965}
5966
5967static void destroy_sched_domains_rcu(struct rcu_head *rcu)
5968{
5969	struct sched_domain *sd = container_of(rcu, struct sched_domain, rcu);
5970
5971	while (sd) {
5972		struct sched_domain *parent = sd->parent;
5973		destroy_sched_domain(sd);
5974		sd = parent;
5975	}
5976}
5977
5978static void destroy_sched_domains(struct sched_domain *sd)
5979{
5980	if (sd)
5981		call_rcu(&sd->rcu, destroy_sched_domains_rcu);
5982}
5983
5984/*
5985 * Keep a special pointer to the highest sched_domain that has
5986 * SD_SHARE_PKG_RESOURCE set (Last Level Cache Domain) for this
5987 * allows us to avoid some pointer chasing select_idle_sibling().
5988 *
5989 * Also keep a unique ID per domain (we use the first cpu number in
5990 * the cpumask of the domain), this allows us to quickly tell if
5991 * two cpus are in the same cache domain, see cpus_share_cache().
5992 */
5993DEFINE_PER_CPU(struct sched_domain *, sd_llc);
5994DEFINE_PER_CPU(int, sd_llc_size);
5995DEFINE_PER_CPU(int, sd_llc_id);
5996DEFINE_PER_CPU(struct sched_domain_shared *, sd_llc_shared);
5997DEFINE_PER_CPU(struct sched_domain *, sd_numa);
5998DEFINE_PER_CPU(struct sched_domain *, sd_asym);
5999
6000static void update_top_cache_domain(int cpu)
6001{
6002	struct sched_domain_shared *sds = NULL;
6003	struct sched_domain *sd;
6004	int id = cpu;
6005	int size = 1;
6006
6007	sd = highest_flag_domain(cpu, SD_SHARE_PKG_RESOURCES);
6008	if (sd) {
6009		id = cpumask_first(sched_domain_span(sd));
6010		size = cpumask_weight(sched_domain_span(sd));
6011		sds = sd->shared;
6012	}
6013
6014	rcu_assign_pointer(per_cpu(sd_llc, cpu), sd);
6015	per_cpu(sd_llc_size, cpu) = size;
6016	per_cpu(sd_llc_id, cpu) = id;
6017	rcu_assign_pointer(per_cpu(sd_llc_shared, cpu), sds);
6018
6019	sd = lowest_flag_domain(cpu, SD_NUMA);
6020	rcu_assign_pointer(per_cpu(sd_numa, cpu), sd);
6021
6022	sd = highest_flag_domain(cpu, SD_ASYM_PACKING);
6023	rcu_assign_pointer(per_cpu(sd_asym, cpu), sd);
6024}
6025
6026/*
6027 * Attach the domain 'sd' to 'cpu' as its base domain. Callers must
6028 * hold the hotplug lock.
6029 */
6030static void
6031cpu_attach_domain(struct sched_domain *sd, struct root_domain *rd, int cpu)
6032{
6033	struct rq *rq = cpu_rq(cpu);
6034	struct sched_domain *tmp;
6035
6036	/* Remove the sched domains which do not contribute to scheduling. */
6037	for (tmp = sd; tmp; ) {
6038		struct sched_domain *parent = tmp->parent;
6039		if (!parent)
6040			break;
6041
6042		if (sd_parent_degenerate(tmp, parent)) {
6043			tmp->parent = parent->parent;
6044			if (parent->parent)
6045				parent->parent->child = tmp;
6046			/*
6047			 * Transfer SD_PREFER_SIBLING down in case of a
6048			 * degenerate parent; the spans match for this
6049			 * so the property transfers.
6050			 */
6051			if (parent->flags & SD_PREFER_SIBLING)
6052				tmp->flags |= SD_PREFER_SIBLING;
6053			destroy_sched_domain(parent);
6054		} else
6055			tmp = tmp->parent;
6056	}
6057
6058	if (sd && sd_degenerate(sd)) {
6059		tmp = sd;
6060		sd = sd->parent;
6061		destroy_sched_domain(tmp);
6062		if (sd)
6063			sd->child = NULL;
6064	}
6065
6066	sched_domain_debug(sd, cpu);
6067
6068	rq_attach_root(rq, rd);
6069	tmp = rq->sd;
6070	rcu_assign_pointer(rq->sd, sd);
6071	destroy_sched_domains(tmp);
6072
6073	update_top_cache_domain(cpu);
6074}
6075
6076/* Setup the mask of cpus configured for isolated domains */
6077static int __init isolated_cpu_setup(char *str)
6078{
6079	int ret;
6080
6081	alloc_bootmem_cpumask_var(&cpu_isolated_map);
6082	ret = cpulist_parse(str, cpu_isolated_map);
6083	if (ret) {
6084		pr_err("sched: Error, all isolcpus= values must be between 0 and %d\n", nr_cpu_ids);
6085		return 0;
6086	}
6087	return 1;
6088}
6089__setup("isolcpus=", isolated_cpu_setup);
6090
6091struct s_data {
6092	struct sched_domain ** __percpu sd;
6093	struct root_domain	*rd;
6094};
6095
6096enum s_alloc {
6097	sa_rootdomain,
6098	sa_sd,
6099	sa_sd_storage,
6100	sa_none,
6101};
6102
6103/*
6104 * Build an iteration mask that can exclude certain CPUs from the upwards
6105 * domain traversal.
6106 *
6107 * Asymmetric node setups can result in situations where the domain tree is of
6108 * unequal depth, make sure to skip domains that already cover the entire
6109 * range.
6110 *
6111 * In that case build_sched_domains() will have terminated the iteration early
6112 * and our sibling sd spans will be empty. Domains should always include the
6113 * cpu they're built on, so check that.
6114 *
6115 */
6116static void build_group_mask(struct sched_domain *sd, struct sched_group *sg)
6117{
6118	const struct cpumask *span = sched_domain_span(sd);
6119	struct sd_data *sdd = sd->private;
6120	struct sched_domain *sibling;
6121	int i;
6122
6123	for_each_cpu(i, span) {
6124		sibling = *per_cpu_ptr(sdd->sd, i);
6125		if (!cpumask_test_cpu(i, sched_domain_span(sibling)))
6126			continue;
6127
6128		cpumask_set_cpu(i, sched_group_mask(sg));
6129	}
6130}
6131
6132/*
6133 * Return the canonical balance cpu for this group, this is the first cpu
6134 * of this group that's also in the iteration mask.
6135 */
6136int group_balance_cpu(struct sched_group *sg)
6137{
6138	return cpumask_first_and(sched_group_cpus(sg), sched_group_mask(sg));
6139}
6140
6141static int
6142build_overlap_sched_groups(struct sched_domain *sd, int cpu)
6143{
6144	struct sched_group *first = NULL, *last = NULL, *groups = NULL, *sg;
6145	const struct cpumask *span = sched_domain_span(sd);
6146	struct cpumask *covered = sched_domains_tmpmask;
6147	struct sd_data *sdd = sd->private;
6148	struct sched_domain *sibling;
6149	int i;
6150
6151	cpumask_clear(covered);
6152
6153	for_each_cpu(i, span) {
6154		struct cpumask *sg_span;
6155
6156		if (cpumask_test_cpu(i, covered))
6157			continue;
6158
6159		sibling = *per_cpu_ptr(sdd->sd, i);
6160
6161		/* See the comment near build_group_mask(). */
6162		if (!cpumask_test_cpu(i, sched_domain_span(sibling)))
6163			continue;
6164
6165		sg = kzalloc_node(sizeof(struct sched_group) + cpumask_size(),
6166				GFP_KERNEL, cpu_to_node(cpu));
6167
6168		if (!sg)
6169			goto fail;
6170
6171		sg_span = sched_group_cpus(sg);
6172		if (sibling->child)
6173			cpumask_copy(sg_span, sched_domain_span(sibling->child));
6174		else
6175			cpumask_set_cpu(i, sg_span);
6176
6177		cpumask_or(covered, covered, sg_span);
6178
6179		sg->sgc = *per_cpu_ptr(sdd->sgc, i);
6180		if (atomic_inc_return(&sg->sgc->ref) == 1)
6181			build_group_mask(sd, sg);
6182
6183		/*
6184		 * Initialize sgc->capacity such that even if we mess up the
6185		 * domains and no possible iteration will get us here, we won't
6186		 * die on a /0 trap.
6187		 */
6188		sg->sgc->capacity = SCHED_CAPACITY_SCALE * cpumask_weight(sg_span);
6189		sg->sgc->min_capacity = SCHED_CAPACITY_SCALE;
6190
6191		/*
6192		 * Make sure the first group of this domain contains the
6193		 * canonical balance cpu. Otherwise the sched_domain iteration
6194		 * breaks. See update_sg_lb_stats().
6195		 */
6196		if ((!groups && cpumask_test_cpu(cpu, sg_span)) ||
6197		    group_balance_cpu(sg) == cpu)
6198			groups = sg;
6199
6200		if (!first)
6201			first = sg;
6202		if (last)
6203			last->next = sg;
6204		last = sg;
6205		last->next = first;
6206	}
6207	sd->groups = groups;
6208
6209	return 0;
6210
6211fail:
6212	free_sched_groups(first, 0);
6213
6214	return -ENOMEM;
6215}
6216
6217static int get_group(int cpu, struct sd_data *sdd, struct sched_group **sg)
6218{
6219	struct sched_domain *sd = *per_cpu_ptr(sdd->sd, cpu);
6220	struct sched_domain *child = sd->child;
6221
6222	if (child)
6223		cpu = cpumask_first(sched_domain_span(child));
6224
6225	if (sg) {
6226		*sg = *per_cpu_ptr(sdd->sg, cpu);
6227		(*sg)->sgc = *per_cpu_ptr(sdd->sgc, cpu);
6228		atomic_set(&(*sg)->sgc->ref, 1); /* for claim_allocations */
6229	}
6230
6231	return cpu;
6232}
6233
6234/*
6235 * build_sched_groups will build a circular linked list of the groups
6236 * covered by the given span, and will set each group's ->cpumask correctly,
6237 * and ->cpu_capacity to 0.
6238 *
6239 * Assumes the sched_domain tree is fully constructed
6240 */
6241static int
6242build_sched_groups(struct sched_domain *sd, int cpu)
6243{
6244	struct sched_group *first = NULL, *last = NULL;
6245	struct sd_data *sdd = sd->private;
6246	const struct cpumask *span = sched_domain_span(sd);
6247	struct cpumask *covered;
6248	int i;
6249
6250	get_group(cpu, sdd, &sd->groups);
6251	atomic_inc(&sd->groups->ref);
6252
6253	if (cpu != cpumask_first(span))
6254		return 0;
6255
6256	lockdep_assert_held(&sched_domains_mutex);
6257	covered = sched_domains_tmpmask;
6258
6259	cpumask_clear(covered);
6260
6261	for_each_cpu(i, span) {
6262		struct sched_group *sg;
6263		int group, j;
6264
6265		if (cpumask_test_cpu(i, covered))
6266			continue;
6267
6268		group = get_group(i, sdd, &sg);
6269		cpumask_setall(sched_group_mask(sg));
6270
6271		for_each_cpu(j, span) {
6272			if (get_group(j, sdd, NULL) != group)
6273				continue;
6274
6275			cpumask_set_cpu(j, covered);
6276			cpumask_set_cpu(j, sched_group_cpus(sg));
6277		}
6278
6279		if (!first)
6280			first = sg;
6281		if (last)
6282			last->next = sg;
6283		last = sg;
6284	}
6285	last->next = first;
6286
6287	return 0;
6288}
6289
6290/*
6291 * Initialize sched groups cpu_capacity.
6292 *
6293 * cpu_capacity indicates the capacity of sched group, which is used while
6294 * distributing the load between different sched groups in a sched domain.
6295 * Typically cpu_capacity for all the groups in a sched domain will be same
6296 * unless there are asymmetries in the topology. If there are asymmetries,
6297 * group having more cpu_capacity will pickup more load compared to the
6298 * group having less cpu_capacity.
6299 */
6300static void init_sched_groups_capacity(int cpu, struct sched_domain *sd)
6301{
6302	struct sched_group *sg = sd->groups;
6303
6304	WARN_ON(!sg);
6305
6306	do {
6307		int cpu, max_cpu = -1;
6308
6309		sg->group_weight = cpumask_weight(sched_group_cpus(sg));
6310
6311		if (!(sd->flags & SD_ASYM_PACKING))
6312			goto next;
6313
6314		for_each_cpu(cpu, sched_group_cpus(sg)) {
6315			if (max_cpu < 0)
6316				max_cpu = cpu;
6317			else if (sched_asym_prefer(cpu, max_cpu))
6318				max_cpu = cpu;
6319		}
6320		sg->asym_prefer_cpu = max_cpu;
6321
6322next:
6323		sg = sg->next;
6324	} while (sg != sd->groups);
6325
6326	if (cpu != group_balance_cpu(sg))
6327		return;
6328
6329	update_group_capacity(sd, cpu);
6330}
6331
6332/*
6333 * Initializers for schedule domains
6334 * Non-inlined to reduce accumulated stack pressure in build_sched_domains()
6335 */
6336
6337static int default_relax_domain_level = -1;
6338int sched_domain_level_max;
6339
6340static int __init setup_relax_domain_level(char *str)
6341{
6342	if (kstrtoint(str, 0, &default_relax_domain_level))
6343		pr_warn("Unable to set relax_domain_level\n");
6344
6345	return 1;
6346}
6347__setup("relax_domain_level=", setup_relax_domain_level);
6348
6349static void set_domain_attribute(struct sched_domain *sd,
6350				 struct sched_domain_attr *attr)
6351{
6352	int request;
6353
6354	if (!attr || attr->relax_domain_level < 0) {
6355		if (default_relax_domain_level < 0)
6356			return;
6357		else
6358			request = default_relax_domain_level;
6359	} else
6360		request = attr->relax_domain_level;
6361	if (request < sd->level) {
6362		/* turn off idle balance on this domain */
6363		sd->flags &= ~(SD_BALANCE_WAKE|SD_BALANCE_NEWIDLE);
6364	} else {
6365		/* turn on idle balance on this domain */
6366		sd->flags |= (SD_BALANCE_WAKE|SD_BALANCE_NEWIDLE);
6367	}
6368}
6369
6370static void __sdt_free(const struct cpumask *cpu_map);
6371static int __sdt_alloc(const struct cpumask *cpu_map);
6372
6373static void __free_domain_allocs(struct s_data *d, enum s_alloc what,
6374				 const struct cpumask *cpu_map)
6375{
6376	switch (what) {
6377	case sa_rootdomain:
6378		if (!atomic_read(&d->rd->refcount))
6379			free_rootdomain(&d->rd->rcu); /* fall through */
6380	case sa_sd:
6381		free_percpu(d->sd); /* fall through */
6382	case sa_sd_storage:
6383		__sdt_free(cpu_map); /* fall through */
6384	case sa_none:
6385		break;
6386	}
6387}
6388
6389static enum s_alloc __visit_domain_allocation_hell(struct s_data *d,
6390						   const struct cpumask *cpu_map)
6391{
6392	memset(d, 0, sizeof(*d));
6393
6394	if (__sdt_alloc(cpu_map))
6395		return sa_sd_storage;
6396	d->sd = alloc_percpu(struct sched_domain *);
6397	if (!d->sd)
6398		return sa_sd_storage;
6399	d->rd = alloc_rootdomain();
6400	if (!d->rd)
6401		return sa_sd;
6402	return sa_rootdomain;
6403}
6404
6405/*
6406 * NULL the sd_data elements we've used to build the sched_domain and
6407 * sched_group structure so that the subsequent __free_domain_allocs()
6408 * will not free the data we're using.
6409 */
6410static void claim_allocations(int cpu, struct sched_domain *sd)
6411{
6412	struct sd_data *sdd = sd->private;
6413
6414	WARN_ON_ONCE(*per_cpu_ptr(sdd->sd, cpu) != sd);
6415	*per_cpu_ptr(sdd->sd, cpu) = NULL;
6416
6417	if (atomic_read(&(*per_cpu_ptr(sdd->sds, cpu))->ref))
6418		*per_cpu_ptr(sdd->sds, cpu) = NULL;
6419
6420	if (atomic_read(&(*per_cpu_ptr(sdd->sg, cpu))->ref))
6421		*per_cpu_ptr(sdd->sg, cpu) = NULL;
6422
6423	if (atomic_read(&(*per_cpu_ptr(sdd->sgc, cpu))->ref))
6424		*per_cpu_ptr(sdd->sgc, cpu) = NULL;
6425}
6426
6427#ifdef CONFIG_NUMA
6428static int sched_domains_numa_levels;
6429enum numa_topology_type sched_numa_topology_type;
6430static int *sched_domains_numa_distance;
6431int sched_max_numa_distance;
6432static struct cpumask ***sched_domains_numa_masks;
6433static int sched_domains_curr_level;
6434#endif
6435
6436/*
6437 * SD_flags allowed in topology descriptions.
6438 *
6439 * These flags are purely descriptive of the topology and do not prescribe
6440 * behaviour. Behaviour is artificial and mapped in the below sd_init()
6441 * function:
6442 *
6443 *   SD_SHARE_CPUCAPACITY   - describes SMT topologies
6444 *   SD_SHARE_PKG_RESOURCES - describes shared caches
6445 *   SD_NUMA                - describes NUMA topologies
6446 *   SD_SHARE_POWERDOMAIN   - describes shared power domain
6447 *   SD_ASYM_CPUCAPACITY    - describes mixed capacity topologies
6448 *
6449 * Odd one out, which beside describing the topology has a quirk also
6450 * prescribes the desired behaviour that goes along with it:
6451 *
6452 *   SD_ASYM_PACKING        - describes SMT quirks
6453 */
6454#define TOPOLOGY_SD_FLAGS		\
6455	(SD_SHARE_CPUCAPACITY |		\
6456	 SD_SHARE_PKG_RESOURCES |	\
6457	 SD_NUMA |			\
6458	 SD_ASYM_PACKING |		\
6459	 SD_ASYM_CPUCAPACITY |		\
6460	 SD_SHARE_POWERDOMAIN)
6461
6462static struct sched_domain *
6463sd_init(struct sched_domain_topology_level *tl,
6464	const struct cpumask *cpu_map,
6465	struct sched_domain *child, int cpu)
6466{
6467	struct sd_data *sdd = &tl->data;
6468	struct sched_domain *sd = *per_cpu_ptr(sdd->sd, cpu);
6469	int sd_id, sd_weight, sd_flags = 0;
6470
6471#ifdef CONFIG_NUMA
6472	/*
6473	 * Ugly hack to pass state to sd_numa_mask()...
6474	 */
6475	sched_domains_curr_level = tl->numa_level;
6476#endif
6477
6478	sd_weight = cpumask_weight(tl->mask(cpu));
6479
6480	if (tl->sd_flags)
6481		sd_flags = (*tl->sd_flags)();
6482	if (WARN_ONCE(sd_flags & ~TOPOLOGY_SD_FLAGS,
6483			"wrong sd_flags in topology description\n"))
6484		sd_flags &= ~TOPOLOGY_SD_FLAGS;
6485
6486	*sd = (struct sched_domain){
6487		.min_interval		= sd_weight,
6488		.max_interval		= 2*sd_weight,
6489		.busy_factor		= 32,
6490		.imbalance_pct		= 125,
6491
6492		.cache_nice_tries	= 0,
6493		.busy_idx		= 0,
6494		.idle_idx		= 0,
6495		.newidle_idx		= 0,
6496		.wake_idx		= 0,
6497		.forkexec_idx		= 0,
6498
6499		.flags			= 1*SD_LOAD_BALANCE
6500					| 1*SD_BALANCE_NEWIDLE
6501					| 1*SD_BALANCE_EXEC
6502					| 1*SD_BALANCE_FORK
6503					| 0*SD_BALANCE_WAKE
6504					| 1*SD_WAKE_AFFINE
6505					| 0*SD_SHARE_CPUCAPACITY
6506					| 0*SD_SHARE_PKG_RESOURCES
6507					| 0*SD_SERIALIZE
6508					| 0*SD_PREFER_SIBLING
6509					| 0*SD_NUMA
6510					| sd_flags
6511					,
6512
6513		.last_balance		= jiffies,
6514		.balance_interval	= sd_weight,
6515		.smt_gain		= 0,
6516		.max_newidle_lb_cost	= 0,
6517		.next_decay_max_lb_cost	= jiffies,
6518		.child			= child,
6519#ifdef CONFIG_SCHED_DEBUG
6520		.name			= tl->name,
6521#endif
6522	};
6523
6524	cpumask_and(sched_domain_span(sd), cpu_map, tl->mask(cpu));
6525	sd_id = cpumask_first(sched_domain_span(sd));
6526
6527	/*
6528	 * Convert topological properties into behaviour.
6529	 */
6530
6531	if (sd->flags & SD_ASYM_CPUCAPACITY) {
6532		struct sched_domain *t = sd;
6533
6534		for_each_lower_domain(t)
6535			t->flags |= SD_BALANCE_WAKE;
6536	}
6537
6538	if (sd->flags & SD_SHARE_CPUCAPACITY) {
6539		sd->flags |= SD_PREFER_SIBLING;
6540		sd->imbalance_pct = 110;
6541		sd->smt_gain = 1178; /* ~15% */
6542
6543	} else if (sd->flags & SD_SHARE_PKG_RESOURCES) {
6544		sd->imbalance_pct = 117;
6545		sd->cache_nice_tries = 1;
6546		sd->busy_idx = 2;
6547
6548#ifdef CONFIG_NUMA
6549	} else if (sd->flags & SD_NUMA) {
6550		sd->cache_nice_tries = 2;
6551		sd->busy_idx = 3;
6552		sd->idle_idx = 2;
6553
6554		sd->flags |= SD_SERIALIZE;
6555		if (sched_domains_numa_distance[tl->numa_level] > RECLAIM_DISTANCE) {
6556			sd->flags &= ~(SD_BALANCE_EXEC |
6557				       SD_BALANCE_FORK |
6558				       SD_WAKE_AFFINE);
6559		}
6560
6561#endif
6562	} else {
6563		sd->flags |= SD_PREFER_SIBLING;
6564		sd->cache_nice_tries = 1;
6565		sd->busy_idx = 2;
6566		sd->idle_idx = 1;
6567	}
6568
6569	/*
6570	 * For all levels sharing cache; connect a sched_domain_shared
6571	 * instance.
6572	 */
6573	if (sd->flags & SD_SHARE_PKG_RESOURCES) {
6574		sd->shared = *per_cpu_ptr(sdd->sds, sd_id);
6575		atomic_inc(&sd->shared->ref);
6576		atomic_set(&sd->shared->nr_busy_cpus, sd_weight);
6577	}
6578
6579	sd->private = sdd;
6580
6581	return sd;
6582}
6583
6584/*
6585 * Topology list, bottom-up.
6586 */
6587static struct sched_domain_topology_level default_topology[] = {
6588#ifdef CONFIG_SCHED_SMT
6589	{ cpu_smt_mask, cpu_smt_flags, SD_INIT_NAME(SMT) },
6590#endif
6591#ifdef CONFIG_SCHED_MC
6592	{ cpu_coregroup_mask, cpu_core_flags, SD_INIT_NAME(MC) },
6593#endif
6594	{ cpu_cpu_mask, SD_INIT_NAME(DIE) },
6595	{ NULL, },
6596};
6597
6598static struct sched_domain_topology_level *sched_domain_topology =
6599	default_topology;
6600
6601#define for_each_sd_topology(tl)			\
6602	for (tl = sched_domain_topology; tl->mask; tl++)
6603
6604void set_sched_topology(struct sched_domain_topology_level *tl)
6605{
6606	if (WARN_ON_ONCE(sched_smp_initialized))
6607		return;
6608
6609	sched_domain_topology = tl;
6610}
6611
6612#ifdef CONFIG_NUMA
6613
6614static const struct cpumask *sd_numa_mask(int cpu)
6615{
6616	return sched_domains_numa_masks[sched_domains_curr_level][cpu_to_node(cpu)];
6617}
6618
6619static void sched_numa_warn(const char *str)
6620{
6621	static int done = false;
6622	int i,j;
6623
6624	if (done)
6625		return;
6626
6627	done = true;
6628
6629	printk(KERN_WARNING "ERROR: %s\n\n", str);
6630
6631	for (i = 0; i < nr_node_ids; i++) {
6632		printk(KERN_WARNING "  ");
6633		for (j = 0; j < nr_node_ids; j++)
6634			printk(KERN_CONT "%02d ", node_distance(i,j));
6635		printk(KERN_CONT "\n");
6636	}
6637	printk(KERN_WARNING "\n");
6638}
6639
6640bool find_numa_distance(int distance)
6641{
6642	int i;
6643
6644	if (distance == node_distance(0, 0))
6645		return true;
6646
6647	for (i = 0; i < sched_domains_numa_levels; i++) {
6648		if (sched_domains_numa_distance[i] == distance)
6649			return true;
6650	}
6651
6652	return false;
6653}
6654
6655/*
6656 * A system can have three types of NUMA topology:
6657 * NUMA_DIRECT: all nodes are directly connected, or not a NUMA system
6658 * NUMA_GLUELESS_MESH: some nodes reachable through intermediary nodes
6659 * NUMA_BACKPLANE: nodes can reach other nodes through a backplane
6660 *
6661 * The difference between a glueless mesh topology and a backplane
6662 * topology lies in whether communication between not directly
6663 * connected nodes goes through intermediary nodes (where programs
6664 * could run), or through backplane controllers. This affects
6665 * placement of programs.
6666 *
6667 * The type of topology can be discerned with the following tests:
6668 * - If the maximum distance between any nodes is 1 hop, the system
6669 *   is directly connected.
6670 * - If for two nodes A and B, located N > 1 hops away from each other,
6671 *   there is an intermediary node C, which is < N hops away from both
6672 *   nodes A and B, the system is a glueless mesh.
6673 */
6674static void init_numa_topology_type(void)
6675{
6676	int a, b, c, n;
6677
6678	n = sched_max_numa_distance;
6679
6680	if (sched_domains_numa_levels <= 1) {
6681		sched_numa_topology_type = NUMA_DIRECT;
6682		return;
6683	}
6684
6685	for_each_online_node(a) {
6686		for_each_online_node(b) {
6687			/* Find two nodes furthest removed from each other. */
6688			if (node_distance(a, b) < n)
6689				continue;
6690
6691			/* Is there an intermediary node between a and b? */
6692			for_each_online_node(c) {
6693				if (node_distance(a, c) < n &&
6694				    node_distance(b, c) < n) {
6695					sched_numa_topology_type =
6696							NUMA_GLUELESS_MESH;
6697					return;
6698				}
6699			}
6700
6701			sched_numa_topology_type = NUMA_BACKPLANE;
6702			return;
6703		}
6704	}
6705}
6706
6707static void sched_init_numa(void)
6708{
6709	int next_distance, curr_distance = node_distance(0, 0);
6710	struct sched_domain_topology_level *tl;
6711	int level = 0;
6712	int i, j, k;
6713
6714	sched_domains_numa_distance = kzalloc(sizeof(int) * nr_node_ids, GFP_KERNEL);
6715	if (!sched_domains_numa_distance)
6716		return;
6717
6718	/*
6719	 * O(nr_nodes^2) deduplicating selection sort -- in order to find the
6720	 * unique distances in the node_distance() table.
6721	 *
6722	 * Assumes node_distance(0,j) includes all distances in
6723	 * node_distance(i,j) in order to avoid cubic time.
6724	 */
6725	next_distance = curr_distance;
6726	for (i = 0; i < nr_node_ids; i++) {
6727		for (j = 0; j < nr_node_ids; j++) {
6728			for (k = 0; k < nr_node_ids; k++) {
6729				int distance = node_distance(i, k);
6730
6731				if (distance > curr_distance &&
6732				    (distance < next_distance ||
6733				     next_distance == curr_distance))
6734					next_distance = distance;
6735
6736				/*
6737				 * While not a strong assumption it would be nice to know
6738				 * about cases where if node A is connected to B, B is not
6739				 * equally connected to A.
6740				 */
6741				if (sched_debug() && node_distance(k, i) != distance)
6742					sched_numa_warn("Node-distance not symmetric");
6743
6744				if (sched_debug() && i && !find_numa_distance(distance))
6745					sched_numa_warn("Node-0 not representative");
6746			}
6747			if (next_distance != curr_distance) {
6748				sched_domains_numa_distance[level++] = next_distance;
6749				sched_domains_numa_levels = level;
6750				curr_distance = next_distance;
6751			} else break;
6752		}
6753
6754		/*
6755		 * In case of sched_debug() we verify the above assumption.
6756		 */
6757		if (!sched_debug())
6758			break;
6759	}
6760
6761	if (!level)
6762		return;
6763
6764	/*
6765	 * 'level' contains the number of unique distances, excluding the
6766	 * identity distance node_distance(i,i).
6767	 *
6768	 * The sched_domains_numa_distance[] array includes the actual distance
6769	 * numbers.
6770	 */
6771
6772	/*
6773	 * Here, we should temporarily reset sched_domains_numa_levels to 0.
6774	 * If it fails to allocate memory for array sched_domains_numa_masks[][],
6775	 * the array will contain less then 'level' members. This could be
6776	 * dangerous when we use it to iterate array sched_domains_numa_masks[][]
6777	 * in other functions.
6778	 *
6779	 * We reset it to 'level' at the end of this function.
6780	 */
6781	sched_domains_numa_levels = 0;
6782
6783	sched_domains_numa_masks = kzalloc(sizeof(void *) * level, GFP_KERNEL);
6784	if (!sched_domains_numa_masks)
6785		return;
6786
6787	/*
6788	 * Now for each level, construct a mask per node which contains all
6789	 * cpus of nodes that are that many hops away from us.
6790	 */
6791	for (i = 0; i < level; i++) {
6792		sched_domains_numa_masks[i] =
6793			kzalloc(nr_node_ids * sizeof(void *), GFP_KERNEL);
6794		if (!sched_domains_numa_masks[i])
6795			return;
6796
6797		for (j = 0; j < nr_node_ids; j++) {
6798			struct cpumask *mask = kzalloc(cpumask_size(), GFP_KERNEL);
6799			if (!mask)
6800				return;
6801
6802			sched_domains_numa_masks[i][j] = mask;
6803
6804			for_each_node(k) {
6805				if (node_distance(j, k) > sched_domains_numa_distance[i])
6806					continue;
6807
6808				cpumask_or(mask, mask, cpumask_of_node(k));
6809			}
6810		}
6811	}
6812
6813	/* Compute default topology size */
6814	for (i = 0; sched_domain_topology[i].mask; i++);
6815
6816	tl = kzalloc((i + level + 1) *
6817			sizeof(struct sched_domain_topology_level), GFP_KERNEL);
6818	if (!tl)
6819		return;
6820
6821	/*
6822	 * Copy the default topology bits..
6823	 */
6824	for (i = 0; sched_domain_topology[i].mask; i++)
6825		tl[i] = sched_domain_topology[i];
6826
6827	/*
6828	 * .. and append 'j' levels of NUMA goodness.
6829	 */
6830	for (j = 0; j < level; i++, j++) {
6831		tl[i] = (struct sched_domain_topology_level){
6832			.mask = sd_numa_mask,
6833			.sd_flags = cpu_numa_flags,
6834			.flags = SDTL_OVERLAP,
6835			.numa_level = j,
6836			SD_INIT_NAME(NUMA)
6837		};
6838	}
6839
6840	sched_domain_topology = tl;
6841
6842	sched_domains_numa_levels = level;
6843	sched_max_numa_distance = sched_domains_numa_distance[level - 1];
6844
6845	init_numa_topology_type();
6846}
6847
6848static void sched_domains_numa_masks_set(unsigned int cpu)
6849{
6850	int node = cpu_to_node(cpu);
6851	int i, j;
6852
6853	for (i = 0; i < sched_domains_numa_levels; i++) {
6854		for (j = 0; j < nr_node_ids; j++) {
6855			if (node_distance(j, node) <= sched_domains_numa_distance[i])
6856				cpumask_set_cpu(cpu, sched_domains_numa_masks[i][j]);
6857		}
6858	}
6859}
6860
6861static void sched_domains_numa_masks_clear(unsigned int cpu)
6862{
6863	int i, j;
6864
6865	for (i = 0; i < sched_domains_numa_levels; i++) {
6866		for (j = 0; j < nr_node_ids; j++)
6867			cpumask_clear_cpu(cpu, sched_domains_numa_masks[i][j]);
6868	}
6869}
6870
6871#else
6872static inline void sched_init_numa(void) { }
6873static void sched_domains_numa_masks_set(unsigned int cpu) { }
6874static void sched_domains_numa_masks_clear(unsigned int cpu) { }
6875#endif /* CONFIG_NUMA */
6876
6877static int __sdt_alloc(const struct cpumask *cpu_map)
6878{
6879	struct sched_domain_topology_level *tl;
6880	int j;
6881
6882	for_each_sd_topology(tl) {
6883		struct sd_data *sdd = &tl->data;
6884
6885		sdd->sd = alloc_percpu(struct sched_domain *);
6886		if (!sdd->sd)
6887			return -ENOMEM;
6888
6889		sdd->sds = alloc_percpu(struct sched_domain_shared *);
6890		if (!sdd->sds)
6891			return -ENOMEM;
6892
6893		sdd->sg = alloc_percpu(struct sched_group *);
6894		if (!sdd->sg)
6895			return -ENOMEM;
6896
6897		sdd->sgc = alloc_percpu(struct sched_group_capacity *);
6898		if (!sdd->sgc)
6899			return -ENOMEM;
6900
6901		for_each_cpu(j, cpu_map) {
6902			struct sched_domain *sd;
6903			struct sched_domain_shared *sds;
6904			struct sched_group *sg;
6905			struct sched_group_capacity *sgc;
6906
6907			sd = kzalloc_node(sizeof(struct sched_domain) + cpumask_size(),
6908					GFP_KERNEL, cpu_to_node(j));
6909			if (!sd)
6910				return -ENOMEM;
6911
6912			*per_cpu_ptr(sdd->sd, j) = sd;
6913
6914			sds = kzalloc_node(sizeof(struct sched_domain_shared),
6915					GFP_KERNEL, cpu_to_node(j));
6916			if (!sds)
6917				return -ENOMEM;
6918
6919			*per_cpu_ptr(sdd->sds, j) = sds;
6920
6921			sg = kzalloc_node(sizeof(struct sched_group) + cpumask_size(),
6922					GFP_KERNEL, cpu_to_node(j));
6923			if (!sg)
6924				return -ENOMEM;
6925
6926			sg->next = sg;
6927
6928			*per_cpu_ptr(sdd->sg, j) = sg;
6929
6930			sgc = kzalloc_node(sizeof(struct sched_group_capacity) + cpumask_size(),
6931					GFP_KERNEL, cpu_to_node(j));
6932			if (!sgc)
6933				return -ENOMEM;
6934
6935			*per_cpu_ptr(sdd->sgc, j) = sgc;
6936		}
6937	}
6938
6939	return 0;
6940}
6941
6942static void __sdt_free(const struct cpumask *cpu_map)
6943{
6944	struct sched_domain_topology_level *tl;
6945	int j;
6946
6947	for_each_sd_topology(tl) {
6948		struct sd_data *sdd = &tl->data;
6949
6950		for_each_cpu(j, cpu_map) {
6951			struct sched_domain *sd;
6952
6953			if (sdd->sd) {
6954				sd = *per_cpu_ptr(sdd->sd, j);
6955				if (sd && (sd->flags & SD_OVERLAP))
6956					free_sched_groups(sd->groups, 0);
6957				kfree(*per_cpu_ptr(sdd->sd, j));
6958			}
6959
6960			if (sdd->sds)
6961				kfree(*per_cpu_ptr(sdd->sds, j));
6962			if (sdd->sg)
6963				kfree(*per_cpu_ptr(sdd->sg, j));
6964			if (sdd->sgc)
6965				kfree(*per_cpu_ptr(sdd->sgc, j));
6966		}
6967		free_percpu(sdd->sd);
6968		sdd->sd = NULL;
6969		free_percpu(sdd->sds);
6970		sdd->sds = NULL;
6971		free_percpu(sdd->sg);
6972		sdd->sg = NULL;
6973		free_percpu(sdd->sgc);
6974		sdd->sgc = NULL;
6975	}
6976}
6977
6978struct sched_domain *build_sched_domain(struct sched_domain_topology_level *tl,
6979		const struct cpumask *cpu_map, struct sched_domain_attr *attr,
6980		struct sched_domain *child, int cpu)
6981{
6982	struct sched_domain *sd = sd_init(tl, cpu_map, child, cpu);
6983
6984	if (child) {
6985		sd->level = child->level + 1;
6986		sched_domain_level_max = max(sched_domain_level_max, sd->level);
6987		child->parent = sd;
6988
6989		if (!cpumask_subset(sched_domain_span(child),
6990				    sched_domain_span(sd))) {
6991			pr_err("BUG: arch topology borken\n");
6992#ifdef CONFIG_SCHED_DEBUG
6993			pr_err("     the %s domain not a subset of the %s domain\n",
6994					child->name, sd->name);
6995#endif
6996			/* Fixup, ensure @sd has at least @child cpus. */
6997			cpumask_or(sched_domain_span(sd),
6998				   sched_domain_span(sd),
6999				   sched_domain_span(child));
7000		}
7001
7002	}
7003	set_domain_attribute(sd, attr);
7004
7005	return sd;
7006}
7007
7008/*
7009 * Build sched domains for a given set of cpus and attach the sched domains
7010 * to the individual cpus
7011 */
7012static int build_sched_domains(const struct cpumask *cpu_map,
7013			       struct sched_domain_attr *attr)
7014{
7015	enum s_alloc alloc_state;
7016	struct sched_domain *sd;
7017	struct s_data d;
7018	struct rq *rq = NULL;
7019	int i, ret = -ENOMEM;
7020
7021	alloc_state = __visit_domain_allocation_hell(&d, cpu_map);
7022	if (alloc_state != sa_rootdomain)
7023		goto error;
7024
7025	/* Set up domains for cpus specified by the cpu_map. */
7026	for_each_cpu(i, cpu_map) {
7027		struct sched_domain_topology_level *tl;
7028
7029		sd = NULL;
7030		for_each_sd_topology(tl) {
7031			sd = build_sched_domain(tl, cpu_map, attr, sd, i);
7032			if (tl == sched_domain_topology)
7033				*per_cpu_ptr(d.sd, i) = sd;
7034			if (tl->flags & SDTL_OVERLAP || sched_feat(FORCE_SD_OVERLAP))
7035				sd->flags |= SD_OVERLAP;
7036			if (cpumask_equal(cpu_map, sched_domain_span(sd)))
7037				break;
7038		}
7039	}
7040
7041	/* Build the groups for the domains */
7042	for_each_cpu(i, cpu_map) {
7043		for (sd = *per_cpu_ptr(d.sd, i); sd; sd = sd->parent) {
7044			sd->span_weight = cpumask_weight(sched_domain_span(sd));
7045			if (sd->flags & SD_OVERLAP) {
7046				if (build_overlap_sched_groups(sd, i))
7047					goto error;
7048			} else {
7049				if (build_sched_groups(sd, i))
7050					goto error;
7051			}
7052		}
7053	}
7054
7055	/* Calculate CPU capacity for physical packages and nodes */
7056	for (i = nr_cpumask_bits-1; i >= 0; i--) {
7057		if (!cpumask_test_cpu(i, cpu_map))
7058			continue;
7059
7060		for (sd = *per_cpu_ptr(d.sd, i); sd; sd = sd->parent) {
7061			claim_allocations(i, sd);
7062			init_sched_groups_capacity(i, sd);
7063		}
7064	}
7065
7066	/* Attach the domains */
7067	rcu_read_lock();
7068	for_each_cpu(i, cpu_map) {
7069		rq = cpu_rq(i);
7070		sd = *per_cpu_ptr(d.sd, i);
7071
7072		/* Use READ_ONCE()/WRITE_ONCE() to avoid load/store tearing: */
7073		if (rq->cpu_capacity_orig > READ_ONCE(d.rd->max_cpu_capacity))
7074			WRITE_ONCE(d.rd->max_cpu_capacity, rq->cpu_capacity_orig);
7075
7076		cpu_attach_domain(sd, d.rd, i);
7077	}
7078	rcu_read_unlock();
7079
7080	if (rq && sched_debug_enabled) {
7081		pr_info("span: %*pbl (max cpu_capacity = %lu)\n",
7082			cpumask_pr_args(cpu_map), rq->rd->max_cpu_capacity);
7083	}
7084
7085	ret = 0;
7086error:
7087	__free_domain_allocs(&d, alloc_state, cpu_map);
7088	return ret;
7089}
7090
7091static cpumask_var_t *doms_cur;	/* current sched domains */
7092static int ndoms_cur;		/* number of sched domains in 'doms_cur' */
7093static struct sched_domain_attr *dattr_cur;
7094				/* attribues of custom domains in 'doms_cur' */
7095
7096/*
7097 * Special case: If a kmalloc of a doms_cur partition (array of
7098 * cpumask) fails, then fallback to a single sched domain,
7099 * as determined by the single cpumask fallback_doms.
7100 */
7101static cpumask_var_t fallback_doms;
7102
7103/*
7104 * arch_update_cpu_topology lets virtualized architectures update the
7105 * cpu core maps. It is supposed to return 1 if the topology changed
7106 * or 0 if it stayed the same.
7107 */
7108int __weak arch_update_cpu_topology(void)
7109{
7110	return 0;
7111}
7112
7113cpumask_var_t *alloc_sched_domains(unsigned int ndoms)
7114{
7115	int i;
7116	cpumask_var_t *doms;
7117
7118	doms = kmalloc(sizeof(*doms) * ndoms, GFP_KERNEL);
7119	if (!doms)
7120		return NULL;
7121	for (i = 0; i < ndoms; i++) {
7122		if (!alloc_cpumask_var(&doms[i], GFP_KERNEL)) {
7123			free_sched_domains(doms, i);
7124			return NULL;
7125		}
7126	}
7127	return doms;
7128}
7129
7130void free_sched_domains(cpumask_var_t doms[], unsigned int ndoms)
7131{
7132	unsigned int i;
7133	for (i = 0; i < ndoms; i++)
7134		free_cpumask_var(doms[i]);
7135	kfree(doms);
7136}
7137
7138/*
7139 * Set up scheduler domains and groups. Callers must hold the hotplug lock.
7140 * For now this just excludes isolated cpus, but could be used to
7141 * exclude other special cases in the future.
7142 */
7143static int init_sched_domains(const struct cpumask *cpu_map)
7144{
7145	int err;
7146
7147	arch_update_cpu_topology();
7148	ndoms_cur = 1;
7149	doms_cur = alloc_sched_domains(ndoms_cur);
7150	if (!doms_cur)
7151		doms_cur = &fallback_doms;
7152	cpumask_andnot(doms_cur[0], cpu_map, cpu_isolated_map);
7153	err = build_sched_domains(doms_cur[0], NULL);
7154	register_sched_domain_sysctl();
7155
7156	return err;
7157}
7158
7159/*
7160 * Detach sched domains from a group of cpus specified in cpu_map
7161 * These cpus will now be attached to the NULL domain
7162 */
7163static void detach_destroy_domains(const struct cpumask *cpu_map)
7164{
7165	int i;
7166
7167	rcu_read_lock();
7168	for_each_cpu(i, cpu_map)
7169		cpu_attach_domain(NULL, &def_root_domain, i);
7170	rcu_read_unlock();
7171}
7172
7173/* handle null as "default" */
7174static int dattrs_equal(struct sched_domain_attr *cur, int idx_cur,
7175			struct sched_domain_attr *new, int idx_new)
7176{
7177	struct sched_domain_attr tmp;
7178
7179	/* fast path */
7180	if (!new && !cur)
7181		return 1;
7182
7183	tmp = SD_ATTR_INIT;
7184	return !memcmp(cur ? (cur + idx_cur) : &tmp,
7185			new ? (new + idx_new) : &tmp,
7186			sizeof(struct sched_domain_attr));
7187}
7188
7189/*
7190 * Partition sched domains as specified by the 'ndoms_new'
7191 * cpumasks in the array doms_new[] of cpumasks. This compares
7192 * doms_new[] to the current sched domain partitioning, doms_cur[].
7193 * It destroys each deleted domain and builds each new domain.
7194 *
7195 * 'doms_new' is an array of cpumask_var_t's of length 'ndoms_new'.
7196 * The masks don't intersect (don't overlap.) We should setup one
7197 * sched domain for each mask. CPUs not in any of the cpumasks will
7198 * not be load balanced. If the same cpumask appears both in the
7199 * current 'doms_cur' domains and in the new 'doms_new', we can leave
7200 * it as it is.
7201 *
7202 * The passed in 'doms_new' should be allocated using
7203 * alloc_sched_domains.  This routine takes ownership of it and will
7204 * free_sched_domains it when done with it. If the caller failed the
7205 * alloc call, then it can pass in doms_new == NULL && ndoms_new == 1,
7206 * and partition_sched_domains() will fallback to the single partition
7207 * 'fallback_doms', it also forces the domains to be rebuilt.
7208 *
7209 * If doms_new == NULL it will be replaced with cpu_online_mask.
7210 * ndoms_new == 0 is a special case for destroying existing domains,
7211 * and it will not create the default domain.
7212 *
7213 * Call with hotplug lock held
7214 */
7215void partition_sched_domains(int ndoms_new, cpumask_var_t doms_new[],
7216			     struct sched_domain_attr *dattr_new)
7217{
7218	int i, j, n;
7219	int new_topology;
7220
7221	mutex_lock(&sched_domains_mutex);
7222
7223	/* always unregister in case we don't destroy any domains */
7224	unregister_sched_domain_sysctl();
7225
7226	/* Let architecture update cpu core mappings. */
7227	new_topology = arch_update_cpu_topology();
7228
7229	n = doms_new ? ndoms_new : 0;
7230
7231	/* Destroy deleted domains */
7232	for (i = 0; i < ndoms_cur; i++) {
7233		for (j = 0; j < n && !new_topology; j++) {
7234			if (cpumask_equal(doms_cur[i], doms_new[j])
7235			    && dattrs_equal(dattr_cur, i, dattr_new, j))
7236				goto match1;
7237		}
7238		/* no match - a current sched domain not in new doms_new[] */
7239		detach_destroy_domains(doms_cur[i]);
7240match1:
7241		;
7242	}
7243
7244	n = ndoms_cur;
7245	if (doms_new == NULL) {
7246		n = 0;
7247		doms_new = &fallback_doms;
7248		cpumask_andnot(doms_new[0], cpu_active_mask, cpu_isolated_map);
7249		WARN_ON_ONCE(dattr_new);
7250	}
7251
7252	/* Build new domains */
7253	for (i = 0; i < ndoms_new; i++) {
7254		for (j = 0; j < n && !new_topology; j++) {
7255			if (cpumask_equal(doms_new[i], doms_cur[j])
7256			    && dattrs_equal(dattr_new, i, dattr_cur, j))
7257				goto match2;
7258		}
7259		/* no match - add a new doms_new */
7260		build_sched_domains(doms_new[i], dattr_new ? dattr_new + i : NULL);
7261match2:
7262		;
7263	}
7264
7265	/* Remember the new sched domains */
7266	if (doms_cur != &fallback_doms)
7267		free_sched_domains(doms_cur, ndoms_cur);
7268	kfree(dattr_cur);	/* kfree(NULL) is safe */
7269	doms_cur = doms_new;
7270	dattr_cur = dattr_new;
7271	ndoms_cur = ndoms_new;
7272
7273	register_sched_domain_sysctl();
7274
7275	mutex_unlock(&sched_domains_mutex);
7276}
7277
7278static int num_cpus_frozen;	/* used to mark begin/end of suspend/resume */
7279
7280/*
7281 * Update cpusets according to cpu_active mask.  If cpusets are
7282 * disabled, cpuset_update_active_cpus() becomes a simple wrapper
7283 * around partition_sched_domains().
7284 *
7285 * If we come here as part of a suspend/resume, don't touch cpusets because we
7286 * want to restore it back to its original state upon resume anyway.
7287 */
7288static void cpuset_cpu_active(void)
7289{
7290	if (cpuhp_tasks_frozen) {
7291		/*
7292		 * num_cpus_frozen tracks how many CPUs are involved in suspend
7293		 * resume sequence. As long as this is not the last online
7294		 * operation in the resume sequence, just build a single sched
7295		 * domain, ignoring cpusets.
7296		 */
7297		num_cpus_frozen--;
7298		if (likely(num_cpus_frozen)) {
7299			partition_sched_domains(1, NULL, NULL);
7300			return;
7301		}
7302		/*
7303		 * This is the last CPU online operation. So fall through and
7304		 * restore the original sched domains by considering the
7305		 * cpuset configurations.
7306		 */
 
7307	}
7308	cpuset_update_active_cpus(true);
7309}
7310
7311static int cpuset_cpu_inactive(unsigned int cpu)
7312{
7313	unsigned long flags;
7314	struct dl_bw *dl_b;
7315	bool overflow;
7316	int cpus;
7317
7318	if (!cpuhp_tasks_frozen) {
7319		rcu_read_lock_sched();
7320		dl_b = dl_bw_of(cpu);
7321
7322		raw_spin_lock_irqsave(&dl_b->lock, flags);
7323		cpus = dl_bw_cpus(cpu);
7324		overflow = __dl_overflow(dl_b, cpus, 0, 0);
7325		raw_spin_unlock_irqrestore(&dl_b->lock, flags);
7326
7327		rcu_read_unlock_sched();
7328
7329		if (overflow)
7330			return -EBUSY;
7331		cpuset_update_active_cpus(false);
7332	} else {
7333		num_cpus_frozen++;
7334		partition_sched_domains(1, NULL, NULL);
7335	}
7336	return 0;
7337}
7338
7339int sched_cpu_activate(unsigned int cpu)
7340{
7341	struct rq *rq = cpu_rq(cpu);
7342	unsigned long flags;
7343
7344	set_cpu_active(cpu, true);
7345
7346	if (sched_smp_initialized) {
7347		sched_domains_numa_masks_set(cpu);
7348		cpuset_cpu_active();
7349	}
7350
7351	/*
7352	 * Put the rq online, if not already. This happens:
7353	 *
7354	 * 1) In the early boot process, because we build the real domains
7355	 *    after all cpus have been brought up.
7356	 *
7357	 * 2) At runtime, if cpuset_cpu_active() fails to rebuild the
7358	 *    domains.
7359	 */
7360	raw_spin_lock_irqsave(&rq->lock, flags);
7361	if (rq->rd) {
7362		BUG_ON(!cpumask_test_cpu(cpu, rq->rd->span));
7363		set_rq_online(rq);
7364	}
7365	raw_spin_unlock_irqrestore(&rq->lock, flags);
7366
7367	update_max_interval();
7368
7369	return 0;
7370}
7371
7372int sched_cpu_deactivate(unsigned int cpu)
7373{
7374	int ret;
7375
7376	set_cpu_active(cpu, false);
7377	/*
7378	 * We've cleared cpu_active_mask, wait for all preempt-disabled and RCU
7379	 * users of this state to go away such that all new such users will
7380	 * observe it.
7381	 *
7382	 * For CONFIG_PREEMPT we have preemptible RCU and its sync_rcu() might
7383	 * not imply sync_sched(), so wait for both.
7384	 *
7385	 * Do sync before park smpboot threads to take care the rcu boost case.
7386	 */
7387	if (IS_ENABLED(CONFIG_PREEMPT))
7388		synchronize_rcu_mult(call_rcu, call_rcu_sched);
7389	else
7390		synchronize_rcu();
7391
7392	if (!sched_smp_initialized)
7393		return 0;
7394
7395	ret = cpuset_cpu_inactive(cpu);
7396	if (ret) {
7397		set_cpu_active(cpu, true);
7398		return ret;
7399	}
7400	sched_domains_numa_masks_clear(cpu);
7401	return 0;
7402}
7403
7404static void sched_rq_cpu_starting(unsigned int cpu)
7405{
7406	struct rq *rq = cpu_rq(cpu);
7407
7408	rq->calc_load_update = calc_load_update;
7409	update_max_interval();
7410}
7411
7412int sched_cpu_starting(unsigned int cpu)
7413{
7414	set_cpu_rq_start_time(cpu);
7415	sched_rq_cpu_starting(cpu);
 
7416	return 0;
7417}
7418
7419#ifdef CONFIG_HOTPLUG_CPU
7420int sched_cpu_dying(unsigned int cpu)
7421{
7422	struct rq *rq = cpu_rq(cpu);
7423	unsigned long flags;
7424
7425	/* Handle pending wakeups and then migrate everything off */
7426	sched_ttwu_pending();
7427	raw_spin_lock_irqsave(&rq->lock, flags);
 
 
7428	if (rq->rd) {
7429		BUG_ON(!cpumask_test_cpu(cpu, rq->rd->span));
7430		set_rq_offline(rq);
7431	}
7432	migrate_tasks(rq);
7433	BUG_ON(rq->nr_running != 1);
7434	raw_spin_unlock_irqrestore(&rq->lock, flags);
 
7435	calc_load_migrate(rq);
7436	update_max_interval();
7437	nohz_balance_exit_idle(cpu);
7438	hrtick_clear(rq);
7439	return 0;
7440}
7441#endif
7442
7443#ifdef CONFIG_SCHED_SMT
7444DEFINE_STATIC_KEY_FALSE(sched_smt_present);
7445
7446static void sched_init_smt(void)
7447{
7448	/*
7449	 * We've enumerated all CPUs and will assume that if any CPU
7450	 * has SMT siblings, CPU0 will too.
7451	 */
7452	if (cpumask_weight(cpu_smt_mask(0)) > 1)
7453		static_branch_enable(&sched_smt_present);
7454}
7455#else
7456static inline void sched_init_smt(void) { }
7457#endif
7458
7459void __init sched_init_smp(void)
7460{
7461	cpumask_var_t non_isolated_cpus;
7462
7463	alloc_cpumask_var(&non_isolated_cpus, GFP_KERNEL);
7464	alloc_cpumask_var(&fallback_doms, GFP_KERNEL);
7465
7466	sched_init_numa();
7467
7468	/*
7469	 * There's no userspace yet to cause hotplug operations; hence all the
7470	 * cpu masks are stable and all blatant races in the below code cannot
7471	 * happen.
7472	 */
7473	mutex_lock(&sched_domains_mutex);
7474	init_sched_domains(cpu_active_mask);
7475	cpumask_andnot(non_isolated_cpus, cpu_possible_mask, cpu_isolated_map);
7476	if (cpumask_empty(non_isolated_cpus))
7477		cpumask_set_cpu(smp_processor_id(), non_isolated_cpus);
7478	mutex_unlock(&sched_domains_mutex);
7479
7480	/* Move init over to a non-isolated CPU */
7481	if (set_cpus_allowed_ptr(current, non_isolated_cpus) < 0)
7482		BUG();
7483	sched_init_granularity();
7484	free_cpumask_var(non_isolated_cpus);
7485
7486	init_sched_rt_class();
7487	init_sched_dl_class();
7488
7489	sched_init_smt();
7490
7491	sched_smp_initialized = true;
7492}
7493
7494static int __init migration_init(void)
7495{
7496	sched_rq_cpu_starting(smp_processor_id());
7497	return 0;
7498}
7499early_initcall(migration_init);
7500
7501#else
7502void __init sched_init_smp(void)
7503{
7504	sched_init_granularity();
7505}
7506#endif /* CONFIG_SMP */
7507
7508int in_sched_functions(unsigned long addr)
7509{
7510	return in_lock_functions(addr) ||
7511		(addr >= (unsigned long)__sched_text_start
7512		&& addr < (unsigned long)__sched_text_end);
7513}
7514
7515#ifdef CONFIG_CGROUP_SCHED
7516/*
7517 * Default task group.
7518 * Every task in system belongs to this group at bootup.
7519 */
7520struct task_group root_task_group;
7521LIST_HEAD(task_groups);
7522
7523/* Cacheline aligned slab cache for task_group */
7524static struct kmem_cache *task_group_cache __read_mostly;
7525#endif
7526
7527DECLARE_PER_CPU(cpumask_var_t, load_balance_mask);
7528DECLARE_PER_CPU(cpumask_var_t, select_idle_mask);
7529
7530#define WAIT_TABLE_BITS 8
7531#define WAIT_TABLE_SIZE (1 << WAIT_TABLE_BITS)
7532static wait_queue_head_t bit_wait_table[WAIT_TABLE_SIZE] __cacheline_aligned;
7533
7534wait_queue_head_t *bit_waitqueue(void *word, int bit)
7535{
7536	const int shift = BITS_PER_LONG == 32 ? 5 : 6;
7537	unsigned long val = (unsigned long)word << shift | bit;
7538
7539	return bit_wait_table + hash_long(val, WAIT_TABLE_BITS);
7540}
7541EXPORT_SYMBOL(bit_waitqueue);
7542
7543void __init sched_init(void)
7544{
7545	int i, j;
7546	unsigned long alloc_size = 0, ptr;
7547
7548	for (i = 0; i < WAIT_TABLE_SIZE; i++)
7549		init_waitqueue_head(bit_wait_table + i);
7550
7551#ifdef CONFIG_FAIR_GROUP_SCHED
7552	alloc_size += 2 * nr_cpu_ids * sizeof(void **);
7553#endif
7554#ifdef CONFIG_RT_GROUP_SCHED
7555	alloc_size += 2 * nr_cpu_ids * sizeof(void **);
7556#endif
7557	if (alloc_size) {
7558		ptr = (unsigned long)kzalloc(alloc_size, GFP_NOWAIT);
7559
7560#ifdef CONFIG_FAIR_GROUP_SCHED
7561		root_task_group.se = (struct sched_entity **)ptr;
7562		ptr += nr_cpu_ids * sizeof(void **);
7563
7564		root_task_group.cfs_rq = (struct cfs_rq **)ptr;
7565		ptr += nr_cpu_ids * sizeof(void **);
7566
7567#endif /* CONFIG_FAIR_GROUP_SCHED */
7568#ifdef CONFIG_RT_GROUP_SCHED
7569		root_task_group.rt_se = (struct sched_rt_entity **)ptr;
7570		ptr += nr_cpu_ids * sizeof(void **);
7571
7572		root_task_group.rt_rq = (struct rt_rq **)ptr;
7573		ptr += nr_cpu_ids * sizeof(void **);
7574
7575#endif /* CONFIG_RT_GROUP_SCHED */
7576	}
7577#ifdef CONFIG_CPUMASK_OFFSTACK
7578	for_each_possible_cpu(i) {
7579		per_cpu(load_balance_mask, i) = (cpumask_var_t)kzalloc_node(
7580			cpumask_size(), GFP_KERNEL, cpu_to_node(i));
7581		per_cpu(select_idle_mask, i) = (cpumask_var_t)kzalloc_node(
7582			cpumask_size(), GFP_KERNEL, cpu_to_node(i));
7583	}
7584#endif /* CONFIG_CPUMASK_OFFSTACK */
7585
7586	init_rt_bandwidth(&def_rt_bandwidth,
7587			global_rt_period(), global_rt_runtime());
7588	init_dl_bandwidth(&def_dl_bandwidth,
7589			global_rt_period(), global_rt_runtime());
7590
7591#ifdef CONFIG_SMP
7592	init_defrootdomain();
7593#endif
7594
7595#ifdef CONFIG_RT_GROUP_SCHED
7596	init_rt_bandwidth(&root_task_group.rt_bandwidth,
7597			global_rt_period(), global_rt_runtime());
7598#endif /* CONFIG_RT_GROUP_SCHED */
7599
7600#ifdef CONFIG_CGROUP_SCHED
7601	task_group_cache = KMEM_CACHE(task_group, 0);
7602
7603	list_add(&root_task_group.list, &task_groups);
7604	INIT_LIST_HEAD(&root_task_group.children);
7605	INIT_LIST_HEAD(&root_task_group.siblings);
7606	autogroup_init(&init_task);
7607#endif /* CONFIG_CGROUP_SCHED */
7608
7609	for_each_possible_cpu(i) {
7610		struct rq *rq;
7611
7612		rq = cpu_rq(i);
7613		raw_spin_lock_init(&rq->lock);
7614		rq->nr_running = 0;
7615		rq->calc_load_active = 0;
7616		rq->calc_load_update = jiffies + LOAD_FREQ;
7617		init_cfs_rq(&rq->cfs);
7618		init_rt_rq(&rq->rt);
7619		init_dl_rq(&rq->dl);
7620#ifdef CONFIG_FAIR_GROUP_SCHED
7621		root_task_group.shares = ROOT_TASK_GROUP_LOAD;
7622		INIT_LIST_HEAD(&rq->leaf_cfs_rq_list);
7623		rq->tmp_alone_branch = &rq->leaf_cfs_rq_list;
7624		/*
7625		 * How much cpu bandwidth does root_task_group get?
7626		 *
7627		 * In case of task-groups formed thr' the cgroup filesystem, it
7628		 * gets 100% of the cpu resources in the system. This overall
7629		 * system cpu resource is divided among the tasks of
7630		 * root_task_group and its child task-groups in a fair manner,
7631		 * based on each entity's (task or task-group's) weight
7632		 * (se->load.weight).
7633		 *
7634		 * In other words, if root_task_group has 10 tasks of weight
7635		 * 1024) and two child groups A0 and A1 (of weight 1024 each),
7636		 * then A0's share of the cpu resource is:
7637		 *
7638		 *	A0's bandwidth = 1024 / (10*1024 + 1024 + 1024) = 8.33%
7639		 *
7640		 * We achieve this by letting root_task_group's tasks sit
7641		 * directly in rq->cfs (i.e root_task_group->se[] = NULL).
7642		 */
7643		init_cfs_bandwidth(&root_task_group.cfs_bandwidth);
7644		init_tg_cfs_entry(&root_task_group, &rq->cfs, NULL, i, NULL);
7645#endif /* CONFIG_FAIR_GROUP_SCHED */
7646
7647		rq->rt.rt_runtime = def_rt_bandwidth.rt_runtime;
7648#ifdef CONFIG_RT_GROUP_SCHED
7649		init_tg_rt_entry(&root_task_group, &rq->rt, NULL, i, NULL);
7650#endif
7651
7652		for (j = 0; j < CPU_LOAD_IDX_MAX; j++)
7653			rq->cpu_load[j] = 0;
7654
7655#ifdef CONFIG_SMP
7656		rq->sd = NULL;
7657		rq->rd = NULL;
7658		rq->cpu_capacity = rq->cpu_capacity_orig = SCHED_CAPACITY_SCALE;
7659		rq->balance_callback = NULL;
7660		rq->active_balance = 0;
7661		rq->next_balance = jiffies;
7662		rq->push_cpu = 0;
7663		rq->cpu = i;
7664		rq->online = 0;
7665		rq->idle_stamp = 0;
7666		rq->avg_idle = 2*sysctl_sched_migration_cost;
7667		rq->max_idle_balance_cost = sysctl_sched_migration_cost;
7668
7669		INIT_LIST_HEAD(&rq->cfs_tasks);
7670
7671		rq_attach_root(rq, &def_root_domain);
7672#ifdef CONFIG_NO_HZ_COMMON
7673		rq->last_load_update_tick = jiffies;
7674		rq->nohz_flags = 0;
7675#endif
7676#ifdef CONFIG_NO_HZ_FULL
7677		rq->last_sched_tick = 0;
7678#endif
7679#endif /* CONFIG_SMP */
7680		init_rq_hrtick(rq);
7681		atomic_set(&rq->nr_iowait, 0);
7682	}
7683
7684	set_load_weight(&init_task);
7685
7686	/*
7687	 * The boot idle thread does lazy MMU switching as well:
7688	 */
7689	atomic_inc(&init_mm.mm_count);
7690	enter_lazy_tlb(&init_mm, current);
7691
7692	/*
7693	 * Make us the idle thread. Technically, schedule() should not be
7694	 * called from this thread, however somewhere below it might be,
7695	 * but because we are the idle thread, we just pick up running again
7696	 * when this runqueue becomes "idle".
7697	 */
7698	init_idle(current, smp_processor_id());
7699
7700	calc_load_update = jiffies + LOAD_FREQ;
7701
7702#ifdef CONFIG_SMP
7703	zalloc_cpumask_var(&sched_domains_tmpmask, GFP_NOWAIT);
7704	/* May be allocated at isolcpus cmdline parse time */
7705	if (cpu_isolated_map == NULL)
7706		zalloc_cpumask_var(&cpu_isolated_map, GFP_NOWAIT);
7707	idle_thread_set_boot_cpu();
7708	set_cpu_rq_start_time(smp_processor_id());
7709#endif
7710	init_sched_fair_class();
7711
7712	init_schedstats();
7713
7714	scheduler_running = 1;
7715}
7716
7717#ifdef CONFIG_DEBUG_ATOMIC_SLEEP
7718static inline int preempt_count_equals(int preempt_offset)
7719{
7720	int nested = preempt_count() + rcu_preempt_depth();
7721
7722	return (nested == preempt_offset);
7723}
7724
7725void __might_sleep(const char *file, int line, int preempt_offset)
7726{
7727	/*
7728	 * Blocking primitives will set (and therefore destroy) current->state,
7729	 * since we will exit with TASK_RUNNING make sure we enter with it,
7730	 * otherwise we will destroy state.
7731	 */
7732	WARN_ONCE(current->state != TASK_RUNNING && current->task_state_change,
7733			"do not call blocking ops when !TASK_RUNNING; "
7734			"state=%lx set at [<%p>] %pS\n",
7735			current->state,
7736			(void *)current->task_state_change,
7737			(void *)current->task_state_change);
7738
7739	___might_sleep(file, line, preempt_offset);
7740}
7741EXPORT_SYMBOL(__might_sleep);
7742
7743void ___might_sleep(const char *file, int line, int preempt_offset)
7744{
7745	static unsigned long prev_jiffy;	/* ratelimiting */
 
 
7746	unsigned long preempt_disable_ip;
7747
7748	rcu_sleep_check(); /* WARN_ON_ONCE() by default, no rate limit reqd. */
 
 
7749	if ((preempt_count_equals(preempt_offset) && !irqs_disabled() &&
7750	     !is_idle_task(current)) ||
7751	    system_state != SYSTEM_RUNNING || oops_in_progress)
 
7752		return;
 
7753	if (time_before(jiffies, prev_jiffy + HZ) && prev_jiffy)
7754		return;
7755	prev_jiffy = jiffies;
7756
7757	/* Save this before calling printk(), since that will clobber it */
7758	preempt_disable_ip = get_preempt_disable_ip(current);
7759
7760	printk(KERN_ERR
7761		"BUG: sleeping function called from invalid context at %s:%d\n",
7762			file, line);
7763	printk(KERN_ERR
7764		"in_atomic(): %d, irqs_disabled(): %d, pid: %d, name: %s\n",
7765			in_atomic(), irqs_disabled(),
7766			current->pid, current->comm);
7767
7768	if (task_stack_end_corrupted(current))
7769		printk(KERN_EMERG "Thread overran stack, or stack corrupted\n");
7770
7771	debug_show_held_locks(current);
7772	if (irqs_disabled())
7773		print_irqtrace_events(current);
7774	if (IS_ENABLED(CONFIG_DEBUG_PREEMPT)
7775	    && !preempt_count_equals(preempt_offset)) {
7776		pr_err("Preemption disabled at:");
7777		print_ip_sym(preempt_disable_ip);
7778		pr_cont("\n");
7779	}
7780	dump_stack();
7781	add_taint(TAINT_WARN, LOCKDEP_STILL_OK);
7782}
7783EXPORT_SYMBOL(___might_sleep);
7784#endif
7785
7786#ifdef CONFIG_MAGIC_SYSRQ
7787void normalize_rt_tasks(void)
7788{
7789	struct task_struct *g, *p;
7790	struct sched_attr attr = {
7791		.sched_policy = SCHED_NORMAL,
7792	};
7793
7794	read_lock(&tasklist_lock);
7795	for_each_process_thread(g, p) {
7796		/*
7797		 * Only normalize user tasks:
7798		 */
7799		if (p->flags & PF_KTHREAD)
7800			continue;
7801
7802		p->se.exec_start = 0;
7803		schedstat_set(p->se.statistics.wait_start,  0);
7804		schedstat_set(p->se.statistics.sleep_start, 0);
7805		schedstat_set(p->se.statistics.block_start, 0);
7806
7807		if (!dl_task(p) && !rt_task(p)) {
7808			/*
7809			 * Renice negative nice level userspace
7810			 * tasks back to 0:
7811			 */
7812			if (task_nice(p) < 0)
7813				set_user_nice(p, 0);
7814			continue;
7815		}
7816
7817		__sched_setscheduler(p, &attr, false, false);
7818	}
7819	read_unlock(&tasklist_lock);
7820}
7821
7822#endif /* CONFIG_MAGIC_SYSRQ */
7823
7824#if defined(CONFIG_IA64) || defined(CONFIG_KGDB_KDB)
7825/*
7826 * These functions are only useful for the IA64 MCA handling, or kdb.
7827 *
7828 * They can only be called when the whole system has been
7829 * stopped - every CPU needs to be quiescent, and no scheduling
7830 * activity can take place. Using them for anything else would
7831 * be a serious bug, and as a result, they aren't even visible
7832 * under any other configuration.
7833 */
7834
7835/**
7836 * curr_task - return the current task for a given cpu.
7837 * @cpu: the processor in question.
7838 *
7839 * ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED!
7840 *
7841 * Return: The current task for @cpu.
7842 */
7843struct task_struct *curr_task(int cpu)
7844{
7845	return cpu_curr(cpu);
7846}
7847
7848#endif /* defined(CONFIG_IA64) || defined(CONFIG_KGDB_KDB) */
7849
7850#ifdef CONFIG_IA64
7851/**
7852 * set_curr_task - set the current task for a given cpu.
7853 * @cpu: the processor in question.
7854 * @p: the task pointer to set.
7855 *
7856 * Description: This function must only be used when non-maskable interrupts
7857 * are serviced on a separate stack. It allows the architecture to switch the
7858 * notion of the current task on a cpu in a non-blocking manner. This function
7859 * must be called with all CPU's synchronized, and interrupts disabled, the
7860 * and caller must save the original value of the current task (see
7861 * curr_task() above) and restore that value before reenabling interrupts and
7862 * re-starting the system.
7863 *
7864 * ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED!
7865 */
7866void ia64_set_curr_task(int cpu, struct task_struct *p)
7867{
7868	cpu_curr(cpu) = p;
7869}
7870
7871#endif
7872
7873#ifdef CONFIG_CGROUP_SCHED
7874/* task_group_lock serializes the addition/removal of task groups */
7875static DEFINE_SPINLOCK(task_group_lock);
7876
7877static void sched_free_group(struct task_group *tg)
7878{
7879	free_fair_sched_group(tg);
7880	free_rt_sched_group(tg);
7881	autogroup_free(tg);
7882	kmem_cache_free(task_group_cache, tg);
7883}
7884
7885/* allocate runqueue etc for a new task group */
7886struct task_group *sched_create_group(struct task_group *parent)
7887{
7888	struct task_group *tg;
7889
7890	tg = kmem_cache_alloc(task_group_cache, GFP_KERNEL | __GFP_ZERO);
7891	if (!tg)
7892		return ERR_PTR(-ENOMEM);
7893
7894	if (!alloc_fair_sched_group(tg, parent))
7895		goto err;
7896
7897	if (!alloc_rt_sched_group(tg, parent))
7898		goto err;
7899
7900	return tg;
7901
7902err:
7903	sched_free_group(tg);
7904	return ERR_PTR(-ENOMEM);
7905}
7906
7907void sched_online_group(struct task_group *tg, struct task_group *parent)
7908{
7909	unsigned long flags;
7910
7911	spin_lock_irqsave(&task_group_lock, flags);
7912	list_add_rcu(&tg->list, &task_groups);
7913
7914	WARN_ON(!parent); /* root should already exist */
 
7915
7916	tg->parent = parent;
7917	INIT_LIST_HEAD(&tg->children);
7918	list_add_rcu(&tg->siblings, &parent->children);
7919	spin_unlock_irqrestore(&task_group_lock, flags);
7920
7921	online_fair_sched_group(tg);
7922}
7923
7924/* rcu callback to free various structures associated with a task group */
7925static void sched_free_group_rcu(struct rcu_head *rhp)
7926{
7927	/* now it should be safe to free those cfs_rqs */
7928	sched_free_group(container_of(rhp, struct task_group, rcu));
7929}
7930
7931void sched_destroy_group(struct task_group *tg)
7932{
7933	/* wait for possible concurrent references to cfs_rqs complete */
7934	call_rcu(&tg->rcu, sched_free_group_rcu);
7935}
7936
7937void sched_offline_group(struct task_group *tg)
7938{
7939	unsigned long flags;
7940
7941	/* end participation in shares distribution */
7942	unregister_fair_sched_group(tg);
7943
7944	spin_lock_irqsave(&task_group_lock, flags);
7945	list_del_rcu(&tg->list);
7946	list_del_rcu(&tg->siblings);
7947	spin_unlock_irqrestore(&task_group_lock, flags);
7948}
7949
7950static void sched_change_group(struct task_struct *tsk, int type)
7951{
7952	struct task_group *tg;
7953
7954	/*
7955	 * All callers are synchronized by task_rq_lock(); we do not use RCU
7956	 * which is pointless here. Thus, we pass "true" to task_css_check()
7957	 * to prevent lockdep warnings.
7958	 */
7959	tg = container_of(task_css_check(tsk, cpu_cgrp_id, true),
7960			  struct task_group, css);
7961	tg = autogroup_task_group(tsk, tg);
7962	tsk->sched_task_group = tg;
7963
7964#ifdef CONFIG_FAIR_GROUP_SCHED
7965	if (tsk->sched_class->task_change_group)
7966		tsk->sched_class->task_change_group(tsk, type);
7967	else
7968#endif
7969		set_task_rq(tsk, task_cpu(tsk));
7970}
7971
7972/*
7973 * Change task's runqueue when it moves between groups.
7974 *
7975 * The caller of this function should have put the task in its new group by
7976 * now. This function just updates tsk->se.cfs_rq and tsk->se.parent to reflect
7977 * its new group.
7978 */
7979void sched_move_task(struct task_struct *tsk)
7980{
7981	int queued, running;
 
7982	struct rq_flags rf;
7983	struct rq *rq;
7984
7985	rq = task_rq_lock(tsk, &rf);
 
7986
7987	running = task_current(rq, tsk);
7988	queued = task_on_rq_queued(tsk);
7989
7990	if (queued)
7991		dequeue_task(rq, tsk, DEQUEUE_SAVE | DEQUEUE_MOVE);
7992	if (unlikely(running))
7993		put_prev_task(rq, tsk);
7994
7995	sched_change_group(tsk, TASK_MOVE_GROUP);
7996
7997	if (queued)
7998		enqueue_task(rq, tsk, ENQUEUE_RESTORE | ENQUEUE_MOVE);
7999	if (unlikely(running))
8000		set_curr_task(rq, tsk);
8001
8002	task_rq_unlock(rq, tsk, &rf);
8003}
8004#endif /* CONFIG_CGROUP_SCHED */
8005
8006#ifdef CONFIG_RT_GROUP_SCHED
8007/*
8008 * Ensure that the real time constraints are schedulable.
8009 */
8010static DEFINE_MUTEX(rt_constraints_mutex);
8011
8012/* Must be called with tasklist_lock held */
8013static inline int tg_has_rt_tasks(struct task_group *tg)
8014{
8015	struct task_struct *g, *p;
8016
8017	/*
8018	 * Autogroups do not have RT tasks; see autogroup_create().
8019	 */
8020	if (task_group_is_autogroup(tg))
8021		return 0;
8022
8023	for_each_process_thread(g, p) {
8024		if (rt_task(p) && task_group(p) == tg)
8025			return 1;
8026	}
8027
8028	return 0;
8029}
8030
8031struct rt_schedulable_data {
8032	struct task_group *tg;
8033	u64 rt_period;
8034	u64 rt_runtime;
8035};
8036
8037static int tg_rt_schedulable(struct task_group *tg, void *data)
8038{
8039	struct rt_schedulable_data *d = data;
8040	struct task_group *child;
8041	unsigned long total, sum = 0;
8042	u64 period, runtime;
8043
8044	period = ktime_to_ns(tg->rt_bandwidth.rt_period);
8045	runtime = tg->rt_bandwidth.rt_runtime;
8046
8047	if (tg == d->tg) {
8048		period = d->rt_period;
8049		runtime = d->rt_runtime;
8050	}
8051
8052	/*
8053	 * Cannot have more runtime than the period.
8054	 */
8055	if (runtime > period && runtime != RUNTIME_INF)
8056		return -EINVAL;
8057
8058	/*
8059	 * Ensure we don't starve existing RT tasks.
8060	 */
8061	if (rt_bandwidth_enabled() && !runtime && tg_has_rt_tasks(tg))
8062		return -EBUSY;
8063
8064	total = to_ratio(period, runtime);
8065
8066	/*
8067	 * Nobody can have more than the global setting allows.
8068	 */
8069	if (total > to_ratio(global_rt_period(), global_rt_runtime()))
8070		return -EINVAL;
8071
8072	/*
8073	 * The sum of our children's runtime should not exceed our own.
8074	 */
8075	list_for_each_entry_rcu(child, &tg->children, siblings) {
8076		period = ktime_to_ns(child->rt_bandwidth.rt_period);
8077		runtime = child->rt_bandwidth.rt_runtime;
8078
8079		if (child == d->tg) {
8080			period = d->rt_period;
8081			runtime = d->rt_runtime;
8082		}
8083
8084		sum += to_ratio(period, runtime);
8085	}
8086
8087	if (sum > total)
8088		return -EINVAL;
8089
8090	return 0;
8091}
8092
8093static int __rt_schedulable(struct task_group *tg, u64 period, u64 runtime)
8094{
8095	int ret;
8096
8097	struct rt_schedulable_data data = {
8098		.tg = tg,
8099		.rt_period = period,
8100		.rt_runtime = runtime,
8101	};
8102
8103	rcu_read_lock();
8104	ret = walk_tg_tree(tg_rt_schedulable, tg_nop, &data);
8105	rcu_read_unlock();
8106
8107	return ret;
8108}
8109
8110static int tg_set_rt_bandwidth(struct task_group *tg,
8111		u64 rt_period, u64 rt_runtime)
8112{
8113	int i, err = 0;
8114
8115	/*
8116	 * Disallowing the root group RT runtime is BAD, it would disallow the
8117	 * kernel creating (and or operating) RT threads.
8118	 */
8119	if (tg == &root_task_group && rt_runtime == 0)
8120		return -EINVAL;
8121
8122	/* No period doesn't make any sense. */
8123	if (rt_period == 0)
8124		return -EINVAL;
8125
8126	mutex_lock(&rt_constraints_mutex);
8127	read_lock(&tasklist_lock);
8128	err = __rt_schedulable(tg, rt_period, rt_runtime);
8129	if (err)
8130		goto unlock;
8131
8132	raw_spin_lock_irq(&tg->rt_bandwidth.rt_runtime_lock);
8133	tg->rt_bandwidth.rt_period = ns_to_ktime(rt_period);
8134	tg->rt_bandwidth.rt_runtime = rt_runtime;
8135
8136	for_each_possible_cpu(i) {
8137		struct rt_rq *rt_rq = tg->rt_rq[i];
8138
8139		raw_spin_lock(&rt_rq->rt_runtime_lock);
8140		rt_rq->rt_runtime = rt_runtime;
8141		raw_spin_unlock(&rt_rq->rt_runtime_lock);
8142	}
8143	raw_spin_unlock_irq(&tg->rt_bandwidth.rt_runtime_lock);
8144unlock:
8145	read_unlock(&tasklist_lock);
8146	mutex_unlock(&rt_constraints_mutex);
8147
8148	return err;
8149}
8150
8151static int sched_group_set_rt_runtime(struct task_group *tg, long rt_runtime_us)
8152{
8153	u64 rt_runtime, rt_period;
8154
8155	rt_period = ktime_to_ns(tg->rt_bandwidth.rt_period);
8156	rt_runtime = (u64)rt_runtime_us * NSEC_PER_USEC;
8157	if (rt_runtime_us < 0)
8158		rt_runtime = RUNTIME_INF;
8159
8160	return tg_set_rt_bandwidth(tg, rt_period, rt_runtime);
8161}
8162
8163static long sched_group_rt_runtime(struct task_group *tg)
8164{
8165	u64 rt_runtime_us;
8166
8167	if (tg->rt_bandwidth.rt_runtime == RUNTIME_INF)
8168		return -1;
8169
8170	rt_runtime_us = tg->rt_bandwidth.rt_runtime;
8171	do_div(rt_runtime_us, NSEC_PER_USEC);
8172	return rt_runtime_us;
8173}
8174
8175static int sched_group_set_rt_period(struct task_group *tg, u64 rt_period_us)
8176{
8177	u64 rt_runtime, rt_period;
8178
8179	rt_period = rt_period_us * NSEC_PER_USEC;
8180	rt_runtime = tg->rt_bandwidth.rt_runtime;
8181
8182	return tg_set_rt_bandwidth(tg, rt_period, rt_runtime);
8183}
8184
8185static long sched_group_rt_period(struct task_group *tg)
8186{
8187	u64 rt_period_us;
8188
8189	rt_period_us = ktime_to_ns(tg->rt_bandwidth.rt_period);
8190	do_div(rt_period_us, NSEC_PER_USEC);
8191	return rt_period_us;
8192}
8193#endif /* CONFIG_RT_GROUP_SCHED */
8194
8195#ifdef CONFIG_RT_GROUP_SCHED
8196static int sched_rt_global_constraints(void)
8197{
8198	int ret = 0;
8199
8200	mutex_lock(&rt_constraints_mutex);
8201	read_lock(&tasklist_lock);
8202	ret = __rt_schedulable(NULL, 0, 0);
8203	read_unlock(&tasklist_lock);
8204	mutex_unlock(&rt_constraints_mutex);
8205
8206	return ret;
8207}
8208
8209static int sched_rt_can_attach(struct task_group *tg, struct task_struct *tsk)
8210{
8211	/* Don't accept realtime tasks when there is no way for them to run */
8212	if (rt_task(tsk) && tg->rt_bandwidth.rt_runtime == 0)
8213		return 0;
8214
8215	return 1;
8216}
8217
8218#else /* !CONFIG_RT_GROUP_SCHED */
8219static int sched_rt_global_constraints(void)
8220{
8221	unsigned long flags;
8222	int i;
8223
8224	raw_spin_lock_irqsave(&def_rt_bandwidth.rt_runtime_lock, flags);
8225	for_each_possible_cpu(i) {
8226		struct rt_rq *rt_rq = &cpu_rq(i)->rt;
8227
8228		raw_spin_lock(&rt_rq->rt_runtime_lock);
8229		rt_rq->rt_runtime = global_rt_runtime();
8230		raw_spin_unlock(&rt_rq->rt_runtime_lock);
8231	}
8232	raw_spin_unlock_irqrestore(&def_rt_bandwidth.rt_runtime_lock, flags);
8233
8234	return 0;
8235}
8236#endif /* CONFIG_RT_GROUP_SCHED */
8237
8238static int sched_dl_global_validate(void)
8239{
8240	u64 runtime = global_rt_runtime();
8241	u64 period = global_rt_period();
8242	u64 new_bw = to_ratio(period, runtime);
8243	struct dl_bw *dl_b;
8244	int cpu, ret = 0;
8245	unsigned long flags;
8246
8247	/*
8248	 * Here we want to check the bandwidth not being set to some
8249	 * value smaller than the currently allocated bandwidth in
8250	 * any of the root_domains.
8251	 *
8252	 * FIXME: Cycling on all the CPUs is overdoing, but simpler than
8253	 * cycling on root_domains... Discussion on different/better
8254	 * solutions is welcome!
8255	 */
8256	for_each_possible_cpu(cpu) {
8257		rcu_read_lock_sched();
8258		dl_b = dl_bw_of(cpu);
8259
8260		raw_spin_lock_irqsave(&dl_b->lock, flags);
8261		if (new_bw < dl_b->total_bw)
8262			ret = -EBUSY;
8263		raw_spin_unlock_irqrestore(&dl_b->lock, flags);
8264
8265		rcu_read_unlock_sched();
8266
8267		if (ret)
8268			break;
8269	}
8270
8271	return ret;
8272}
8273
8274static void sched_dl_do_global(void)
8275{
8276	u64 new_bw = -1;
8277	struct dl_bw *dl_b;
8278	int cpu;
8279	unsigned long flags;
8280
8281	def_dl_bandwidth.dl_period = global_rt_period();
8282	def_dl_bandwidth.dl_runtime = global_rt_runtime();
8283
8284	if (global_rt_runtime() != RUNTIME_INF)
8285		new_bw = to_ratio(global_rt_period(), global_rt_runtime());
8286
8287	/*
8288	 * FIXME: As above...
8289	 */
8290	for_each_possible_cpu(cpu) {
8291		rcu_read_lock_sched();
8292		dl_b = dl_bw_of(cpu);
8293
8294		raw_spin_lock_irqsave(&dl_b->lock, flags);
8295		dl_b->bw = new_bw;
8296		raw_spin_unlock_irqrestore(&dl_b->lock, flags);
8297
8298		rcu_read_unlock_sched();
8299	}
8300}
8301
8302static int sched_rt_global_validate(void)
8303{
8304	if (sysctl_sched_rt_period <= 0)
8305		return -EINVAL;
8306
8307	if ((sysctl_sched_rt_runtime != RUNTIME_INF) &&
8308		(sysctl_sched_rt_runtime > sysctl_sched_rt_period))
8309		return -EINVAL;
8310
8311	return 0;
8312}
8313
8314static void sched_rt_do_global(void)
8315{
8316	def_rt_bandwidth.rt_runtime = global_rt_runtime();
8317	def_rt_bandwidth.rt_period = ns_to_ktime(global_rt_period());
8318}
8319
8320int sched_rt_handler(struct ctl_table *table, int write,
8321		void __user *buffer, size_t *lenp,
8322		loff_t *ppos)
8323{
8324	int old_period, old_runtime;
8325	static DEFINE_MUTEX(mutex);
8326	int ret;
8327
8328	mutex_lock(&mutex);
8329	old_period = sysctl_sched_rt_period;
8330	old_runtime = sysctl_sched_rt_runtime;
8331
8332	ret = proc_dointvec(table, write, buffer, lenp, ppos);
8333
8334	if (!ret && write) {
8335		ret = sched_rt_global_validate();
8336		if (ret)
8337			goto undo;
8338
8339		ret = sched_dl_global_validate();
8340		if (ret)
8341			goto undo;
8342
8343		ret = sched_rt_global_constraints();
8344		if (ret)
8345			goto undo;
8346
8347		sched_rt_do_global();
8348		sched_dl_do_global();
8349	}
8350	if (0) {
8351undo:
8352		sysctl_sched_rt_period = old_period;
8353		sysctl_sched_rt_runtime = old_runtime;
8354	}
8355	mutex_unlock(&mutex);
8356
8357	return ret;
8358}
8359
8360int sched_rr_handler(struct ctl_table *table, int write,
8361		void __user *buffer, size_t *lenp,
8362		loff_t *ppos)
8363{
8364	int ret;
8365	static DEFINE_MUTEX(mutex);
8366
8367	mutex_lock(&mutex);
8368	ret = proc_dointvec(table, write, buffer, lenp, ppos);
8369	/* make sure that internally we keep jiffies */
8370	/* also, writing zero resets timeslice to default */
8371	if (!ret && write) {
8372		sched_rr_timeslice = sched_rr_timeslice <= 0 ?
8373			RR_TIMESLICE : msecs_to_jiffies(sched_rr_timeslice);
8374	}
8375	mutex_unlock(&mutex);
8376	return ret;
8377}
8378
8379#ifdef CONFIG_CGROUP_SCHED
8380
8381static inline struct task_group *css_tg(struct cgroup_subsys_state *css)
8382{
8383	return css ? container_of(css, struct task_group, css) : NULL;
8384}
8385
8386static struct cgroup_subsys_state *
8387cpu_cgroup_css_alloc(struct cgroup_subsys_state *parent_css)
8388{
8389	struct task_group *parent = css_tg(parent_css);
8390	struct task_group *tg;
8391
8392	if (!parent) {
8393		/* This is early initialization for the top cgroup */
8394		return &root_task_group.css;
8395	}
8396
8397	tg = sched_create_group(parent);
8398	if (IS_ERR(tg))
8399		return ERR_PTR(-ENOMEM);
8400
8401	sched_online_group(tg, parent);
8402
8403	return &tg->css;
8404}
8405
 
 
 
 
 
 
 
 
 
 
 
8406static void cpu_cgroup_css_released(struct cgroup_subsys_state *css)
8407{
8408	struct task_group *tg = css_tg(css);
8409
8410	sched_offline_group(tg);
8411}
8412
8413static void cpu_cgroup_css_free(struct cgroup_subsys_state *css)
8414{
8415	struct task_group *tg = css_tg(css);
8416
8417	/*
8418	 * Relies on the RCU grace period between css_released() and this.
8419	 */
8420	sched_free_group(tg);
8421}
8422
8423/*
8424 * This is called before wake_up_new_task(), therefore we really only
8425 * have to set its group bits, all the other stuff does not apply.
8426 */
8427static void cpu_cgroup_fork(struct task_struct *task)
8428{
8429	struct rq_flags rf;
8430	struct rq *rq;
8431
8432	rq = task_rq_lock(task, &rf);
8433
 
8434	sched_change_group(task, TASK_SET_GROUP);
8435
8436	task_rq_unlock(rq, task, &rf);
8437}
8438
8439static int cpu_cgroup_can_attach(struct cgroup_taskset *tset)
8440{
8441	struct task_struct *task;
8442	struct cgroup_subsys_state *css;
8443	int ret = 0;
8444
8445	cgroup_taskset_for_each(task, css, tset) {
8446#ifdef CONFIG_RT_GROUP_SCHED
8447		if (!sched_rt_can_attach(css_tg(css), task))
8448			return -EINVAL;
8449#else
8450		/* We don't support RT-tasks being in separate groups */
8451		if (task->sched_class != &fair_sched_class)
8452			return -EINVAL;
8453#endif
8454		/*
8455		 * Serialize against wake_up_new_task() such that if its
8456		 * running, we're sure to observe its full state.
8457		 */
8458		raw_spin_lock_irq(&task->pi_lock);
8459		/*
8460		 * Avoid calling sched_move_task() before wake_up_new_task()
8461		 * has happened. This would lead to problems with PELT, due to
8462		 * move wanting to detach+attach while we're not attached yet.
8463		 */
8464		if (task->state == TASK_NEW)
8465			ret = -EINVAL;
8466		raw_spin_unlock_irq(&task->pi_lock);
8467
8468		if (ret)
8469			break;
8470	}
8471	return ret;
8472}
8473
8474static void cpu_cgroup_attach(struct cgroup_taskset *tset)
8475{
8476	struct task_struct *task;
8477	struct cgroup_subsys_state *css;
8478
8479	cgroup_taskset_for_each(task, css, tset)
8480		sched_move_task(task);
8481}
8482
8483#ifdef CONFIG_FAIR_GROUP_SCHED
8484static int cpu_shares_write_u64(struct cgroup_subsys_state *css,
8485				struct cftype *cftype, u64 shareval)
8486{
8487	return sched_group_set_shares(css_tg(css), scale_load(shareval));
8488}
8489
8490static u64 cpu_shares_read_u64(struct cgroup_subsys_state *css,
8491			       struct cftype *cft)
8492{
8493	struct task_group *tg = css_tg(css);
8494
8495	return (u64) scale_load_down(tg->shares);
8496}
8497
8498#ifdef CONFIG_CFS_BANDWIDTH
8499static DEFINE_MUTEX(cfs_constraints_mutex);
8500
8501const u64 max_cfs_quota_period = 1 * NSEC_PER_SEC; /* 1s */
8502const u64 min_cfs_quota_period = 1 * NSEC_PER_MSEC; /* 1ms */
8503
8504static int __cfs_schedulable(struct task_group *tg, u64 period, u64 runtime);
8505
8506static int tg_set_cfs_bandwidth(struct task_group *tg, u64 period, u64 quota)
8507{
8508	int i, ret = 0, runtime_enabled, runtime_was_enabled;
8509	struct cfs_bandwidth *cfs_b = &tg->cfs_bandwidth;
8510
8511	if (tg == &root_task_group)
8512		return -EINVAL;
8513
8514	/*
8515	 * Ensure we have at some amount of bandwidth every period.  This is
8516	 * to prevent reaching a state of large arrears when throttled via
8517	 * entity_tick() resulting in prolonged exit starvation.
8518	 */
8519	if (quota < min_cfs_quota_period || period < min_cfs_quota_period)
8520		return -EINVAL;
8521
8522	/*
8523	 * Likewise, bound things on the otherside by preventing insane quota
8524	 * periods.  This also allows us to normalize in computing quota
8525	 * feasibility.
8526	 */
8527	if (period > max_cfs_quota_period)
8528		return -EINVAL;
8529
8530	/*
8531	 * Prevent race between setting of cfs_rq->runtime_enabled and
8532	 * unthrottle_offline_cfs_rqs().
8533	 */
8534	get_online_cpus();
8535	mutex_lock(&cfs_constraints_mutex);
8536	ret = __cfs_schedulable(tg, period, quota);
8537	if (ret)
8538		goto out_unlock;
8539
8540	runtime_enabled = quota != RUNTIME_INF;
8541	runtime_was_enabled = cfs_b->quota != RUNTIME_INF;
8542	/*
8543	 * If we need to toggle cfs_bandwidth_used, off->on must occur
8544	 * before making related changes, and on->off must occur afterwards
8545	 */
8546	if (runtime_enabled && !runtime_was_enabled)
8547		cfs_bandwidth_usage_inc();
8548	raw_spin_lock_irq(&cfs_b->lock);
8549	cfs_b->period = ns_to_ktime(period);
8550	cfs_b->quota = quota;
8551
8552	__refill_cfs_bandwidth_runtime(cfs_b);
8553	/* restart the period timer (if active) to handle new period expiry */
 
8554	if (runtime_enabled)
8555		start_cfs_bandwidth(cfs_b);
 
8556	raw_spin_unlock_irq(&cfs_b->lock);
8557
8558	for_each_online_cpu(i) {
8559		struct cfs_rq *cfs_rq = tg->cfs_rq[i];
8560		struct rq *rq = cfs_rq->rq;
 
8561
8562		raw_spin_lock_irq(&rq->lock);
8563		cfs_rq->runtime_enabled = runtime_enabled;
8564		cfs_rq->runtime_remaining = 0;
8565
8566		if (cfs_rq->throttled)
8567			unthrottle_cfs_rq(cfs_rq);
8568		raw_spin_unlock_irq(&rq->lock);
8569	}
8570	if (runtime_was_enabled && !runtime_enabled)
8571		cfs_bandwidth_usage_dec();
8572out_unlock:
8573	mutex_unlock(&cfs_constraints_mutex);
8574	put_online_cpus();
8575
8576	return ret;
8577}
8578
8579int tg_set_cfs_quota(struct task_group *tg, long cfs_quota_us)
8580{
8581	u64 quota, period;
8582
8583	period = ktime_to_ns(tg->cfs_bandwidth.period);
8584	if (cfs_quota_us < 0)
8585		quota = RUNTIME_INF;
8586	else
8587		quota = (u64)cfs_quota_us * NSEC_PER_USEC;
8588
8589	return tg_set_cfs_bandwidth(tg, period, quota);
8590}
8591
8592long tg_get_cfs_quota(struct task_group *tg)
8593{
8594	u64 quota_us;
8595
8596	if (tg->cfs_bandwidth.quota == RUNTIME_INF)
8597		return -1;
8598
8599	quota_us = tg->cfs_bandwidth.quota;
8600	do_div(quota_us, NSEC_PER_USEC);
8601
8602	return quota_us;
8603}
8604
8605int tg_set_cfs_period(struct task_group *tg, long cfs_period_us)
8606{
8607	u64 quota, period;
8608
8609	period = (u64)cfs_period_us * NSEC_PER_USEC;
8610	quota = tg->cfs_bandwidth.quota;
8611
8612	return tg_set_cfs_bandwidth(tg, period, quota);
8613}
8614
8615long tg_get_cfs_period(struct task_group *tg)
8616{
8617	u64 cfs_period_us;
8618
8619	cfs_period_us = ktime_to_ns(tg->cfs_bandwidth.period);
8620	do_div(cfs_period_us, NSEC_PER_USEC);
8621
8622	return cfs_period_us;
8623}
8624
8625static s64 cpu_cfs_quota_read_s64(struct cgroup_subsys_state *css,
8626				  struct cftype *cft)
8627{
8628	return tg_get_cfs_quota(css_tg(css));
8629}
8630
8631static int cpu_cfs_quota_write_s64(struct cgroup_subsys_state *css,
8632				   struct cftype *cftype, s64 cfs_quota_us)
8633{
8634	return tg_set_cfs_quota(css_tg(css), cfs_quota_us);
8635}
8636
8637static u64 cpu_cfs_period_read_u64(struct cgroup_subsys_state *css,
8638				   struct cftype *cft)
8639{
8640	return tg_get_cfs_period(css_tg(css));
8641}
8642
8643static int cpu_cfs_period_write_u64(struct cgroup_subsys_state *css,
8644				    struct cftype *cftype, u64 cfs_period_us)
8645{
8646	return tg_set_cfs_period(css_tg(css), cfs_period_us);
8647}
8648
8649struct cfs_schedulable_data {
8650	struct task_group *tg;
8651	u64 period, quota;
8652};
8653
8654/*
8655 * normalize group quota/period to be quota/max_period
8656 * note: units are usecs
8657 */
8658static u64 normalize_cfs_quota(struct task_group *tg,
8659			       struct cfs_schedulable_data *d)
8660{
8661	u64 quota, period;
8662
8663	if (tg == d->tg) {
8664		period = d->period;
8665		quota = d->quota;
8666	} else {
8667		period = tg_get_cfs_period(tg);
8668		quota = tg_get_cfs_quota(tg);
8669	}
8670
8671	/* note: these should typically be equivalent */
8672	if (quota == RUNTIME_INF || quota == -1)
8673		return RUNTIME_INF;
8674
8675	return to_ratio(period, quota);
8676}
8677
8678static int tg_cfs_schedulable_down(struct task_group *tg, void *data)
8679{
8680	struct cfs_schedulable_data *d = data;
8681	struct cfs_bandwidth *cfs_b = &tg->cfs_bandwidth;
8682	s64 quota = 0, parent_quota = -1;
8683
8684	if (!tg->parent) {
8685		quota = RUNTIME_INF;
8686	} else {
8687		struct cfs_bandwidth *parent_b = &tg->parent->cfs_bandwidth;
8688
8689		quota = normalize_cfs_quota(tg, d);
8690		parent_quota = parent_b->hierarchical_quota;
8691
8692		/*
8693		 * ensure max(child_quota) <= parent_quota, inherit when no
8694		 * limit is set
 
8695		 */
8696		if (quota == RUNTIME_INF)
8697			quota = parent_quota;
8698		else if (parent_quota != RUNTIME_INF && quota > parent_quota)
8699			return -EINVAL;
 
 
 
 
8700	}
8701	cfs_b->hierarchical_quota = quota;
8702
8703	return 0;
8704}
8705
8706static int __cfs_schedulable(struct task_group *tg, u64 period, u64 quota)
8707{
8708	int ret;
8709	struct cfs_schedulable_data data = {
8710		.tg = tg,
8711		.period = period,
8712		.quota = quota,
8713	};
8714
8715	if (quota != RUNTIME_INF) {
8716		do_div(data.period, NSEC_PER_USEC);
8717		do_div(data.quota, NSEC_PER_USEC);
8718	}
8719
8720	rcu_read_lock();
8721	ret = walk_tg_tree(tg_cfs_schedulable_down, tg_nop, &data);
8722	rcu_read_unlock();
8723
8724	return ret;
8725}
8726
8727static int cpu_stats_show(struct seq_file *sf, void *v)
8728{
8729	struct task_group *tg = css_tg(seq_css(sf));
8730	struct cfs_bandwidth *cfs_b = &tg->cfs_bandwidth;
8731
8732	seq_printf(sf, "nr_periods %d\n", cfs_b->nr_periods);
8733	seq_printf(sf, "nr_throttled %d\n", cfs_b->nr_throttled);
8734	seq_printf(sf, "throttled_time %llu\n", cfs_b->throttled_time);
8735
8736	return 0;
8737}
8738#endif /* CONFIG_CFS_BANDWIDTH */
8739#endif /* CONFIG_FAIR_GROUP_SCHED */
8740
8741#ifdef CONFIG_RT_GROUP_SCHED
8742static int cpu_rt_runtime_write(struct cgroup_subsys_state *css,
8743				struct cftype *cft, s64 val)
8744{
8745	return sched_group_set_rt_runtime(css_tg(css), val);
8746}
8747
8748static s64 cpu_rt_runtime_read(struct cgroup_subsys_state *css,
8749			       struct cftype *cft)
8750{
8751	return sched_group_rt_runtime(css_tg(css));
8752}
8753
8754static int cpu_rt_period_write_uint(struct cgroup_subsys_state *css,
8755				    struct cftype *cftype, u64 rt_period_us)
8756{
8757	return sched_group_set_rt_period(css_tg(css), rt_period_us);
8758}
8759
8760static u64 cpu_rt_period_read_uint(struct cgroup_subsys_state *css,
8761				   struct cftype *cft)
8762{
8763	return sched_group_rt_period(css_tg(css));
8764}
8765#endif /* CONFIG_RT_GROUP_SCHED */
8766
8767static struct cftype cpu_files[] = {
8768#ifdef CONFIG_FAIR_GROUP_SCHED
8769	{
8770		.name = "shares",
8771		.read_u64 = cpu_shares_read_u64,
8772		.write_u64 = cpu_shares_write_u64,
8773	},
8774#endif
8775#ifdef CONFIG_CFS_BANDWIDTH
8776	{
8777		.name = "cfs_quota_us",
8778		.read_s64 = cpu_cfs_quota_read_s64,
8779		.write_s64 = cpu_cfs_quota_write_s64,
8780	},
8781	{
8782		.name = "cfs_period_us",
8783		.read_u64 = cpu_cfs_period_read_u64,
8784		.write_u64 = cpu_cfs_period_write_u64,
8785	},
8786	{
8787		.name = "stat",
8788		.seq_show = cpu_stats_show,
8789	},
8790#endif
8791#ifdef CONFIG_RT_GROUP_SCHED
8792	{
8793		.name = "rt_runtime_us",
8794		.read_s64 = cpu_rt_runtime_read,
8795		.write_s64 = cpu_rt_runtime_write,
8796	},
8797	{
8798		.name = "rt_period_us",
8799		.read_u64 = cpu_rt_period_read_uint,
8800		.write_u64 = cpu_rt_period_write_uint,
8801	},
8802#endif
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
8803	{ }	/* terminate */
8804};
8805
8806struct cgroup_subsys cpu_cgrp_subsys = {
8807	.css_alloc	= cpu_cgroup_css_alloc,
 
8808	.css_released	= cpu_cgroup_css_released,
8809	.css_free	= cpu_cgroup_css_free,
 
8810	.fork		= cpu_cgroup_fork,
8811	.can_attach	= cpu_cgroup_can_attach,
8812	.attach		= cpu_cgroup_attach,
8813	.legacy_cftypes	= cpu_files,
 
8814	.early_init	= true,
 
8815};
8816
8817#endif	/* CONFIG_CGROUP_SCHED */
8818
8819void dump_cpu_task(int cpu)
8820{
8821	pr_info("Task dump for CPU %d:\n", cpu);
8822	sched_show_task(cpu_curr(cpu));
8823}
8824
8825/*
8826 * Nice levels are multiplicative, with a gentle 10% change for every
8827 * nice level changed. I.e. when a CPU-bound task goes from nice 0 to
8828 * nice 1, it will get ~10% less CPU time than another CPU-bound task
8829 * that remained on nice 0.
8830 *
8831 * The "10% effect" is relative and cumulative: from _any_ nice level,
8832 * if you go up 1 level, it's -10% CPU usage, if you go down 1 level
8833 * it's +10% CPU usage. (to achieve that we use a multiplier of 1.25.
8834 * If a task goes up by ~10% and another task goes down by ~10% then
8835 * the relative distance between them is ~25%.)
8836 */
8837const int sched_prio_to_weight[40] = {
8838 /* -20 */     88761,     71755,     56483,     46273,     36291,
8839 /* -15 */     29154,     23254,     18705,     14949,     11916,
8840 /* -10 */      9548,      7620,      6100,      4904,      3906,
8841 /*  -5 */      3121,      2501,      1991,      1586,      1277,
8842 /*   0 */      1024,       820,       655,       526,       423,
8843 /*   5 */       335,       272,       215,       172,       137,
8844 /*  10 */       110,        87,        70,        56,        45,
8845 /*  15 */        36,        29,        23,        18,        15,
8846};
8847
8848/*
8849 * Inverse (2^32/x) values of the sched_prio_to_weight[] array, precalculated.
8850 *
8851 * In cases where the weight does not change often, we can use the
8852 * precalculated inverse to speed up arithmetics by turning divisions
8853 * into multiplications:
8854 */
8855const u32 sched_prio_to_wmult[40] = {
8856 /* -20 */     48388,     59856,     76040,     92818,    118348,
8857 /* -15 */    147320,    184698,    229616,    287308,    360437,
8858 /* -10 */    449829,    563644,    704093,    875809,   1099582,
8859 /*  -5 */   1376151,   1717300,   2157191,   2708050,   3363326,
8860 /*   0 */   4194304,   5237765,   6557202,   8165337,  10153587,
8861 /*   5 */  12820798,  15790321,  19976592,  24970740,  31350126,
8862 /*  10 */  39045157,  49367440,  61356676,  76695844,  95443717,
8863 /*  15 */ 119304647, 148102320, 186737708, 238609294, 286331153,
8864};