xref: /openbmc/linux/kernel/sched/core.c (revision bcda5fd3)
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  *  kernel/sched/core.c
4  *
5  *  Core kernel scheduler code and related syscalls
6  *
7  *  Copyright (C) 1991-2002  Linus Torvalds
8  */
9 #define CREATE_TRACE_POINTS
10 #include <trace/events/sched.h>
11 #undef CREATE_TRACE_POINTS
12 
13 #include "sched.h"
14 
15 #include <linux/nospec.h>
16 
17 #include <linux/kcov.h>
18 #include <linux/scs.h>
19 
20 #include <asm/switch_to.h>
21 #include <asm/tlb.h>
22 
23 #include "../workqueue_internal.h"
24 #include "../../fs/io-wq.h"
25 #include "../smpboot.h"
26 
27 #include "pelt.h"
28 #include "smp.h"
29 
30 /*
31  * Export tracepoints that act as a bare tracehook (ie: have no trace event
32  * associated with them) to allow external modules to probe them.
33  */
34 EXPORT_TRACEPOINT_SYMBOL_GPL(pelt_cfs_tp);
35 EXPORT_TRACEPOINT_SYMBOL_GPL(pelt_rt_tp);
36 EXPORT_TRACEPOINT_SYMBOL_GPL(pelt_dl_tp);
37 EXPORT_TRACEPOINT_SYMBOL_GPL(pelt_irq_tp);
38 EXPORT_TRACEPOINT_SYMBOL_GPL(pelt_se_tp);
39 EXPORT_TRACEPOINT_SYMBOL_GPL(sched_cpu_capacity_tp);
40 EXPORT_TRACEPOINT_SYMBOL_GPL(sched_overutilized_tp);
41 EXPORT_TRACEPOINT_SYMBOL_GPL(sched_util_est_cfs_tp);
42 EXPORT_TRACEPOINT_SYMBOL_GPL(sched_util_est_se_tp);
43 EXPORT_TRACEPOINT_SYMBOL_GPL(sched_update_nr_running_tp);
44 
45 DEFINE_PER_CPU_SHARED_ALIGNED(struct rq, runqueues);
46 
47 #ifdef CONFIG_SCHED_DEBUG
48 /*
49  * Debugging: various feature bits
50  *
51  * If SCHED_DEBUG is disabled, each compilation unit has its own copy of
52  * sysctl_sched_features, defined in sched.h, to allow constants propagation
53  * at compile time and compiler optimization based on features default.
54  */
55 #define SCHED_FEAT(name, enabled)	\
56 	(1UL << __SCHED_FEAT_##name) * enabled |
57 const_debug unsigned int sysctl_sched_features =
58 #include "features.h"
59 	0;
60 #undef SCHED_FEAT
61 
62 /*
63  * Print a warning if need_resched is set for the given duration (if
64  * LATENCY_WARN is enabled).
65  *
66  * If sysctl_resched_latency_warn_once is set, only one warning will be shown
67  * per boot.
68  */
69 __read_mostly int sysctl_resched_latency_warn_ms = 100;
70 __read_mostly int sysctl_resched_latency_warn_once = 1;
71 #endif /* CONFIG_SCHED_DEBUG */
72 
73 /*
74  * Number of tasks to iterate in a single balance run.
75  * Limited because this is done with IRQs disabled.
76  */
77 const_debug unsigned int sysctl_sched_nr_migrate = 32;
78 
79 /*
80  * period over which we measure -rt task CPU usage in us.
81  * default: 1s
82  */
83 unsigned int sysctl_sched_rt_period = 1000000;
84 
85 __read_mostly int scheduler_running;
86 
87 #ifdef CONFIG_SCHED_CORE
88 
89 DEFINE_STATIC_KEY_FALSE(__sched_core_enabled);
90 
91 /* kernel prio, less is more */
92 static inline int __task_prio(struct task_struct *p)
93 {
94 	if (p->sched_class == &stop_sched_class) /* trumps deadline */
95 		return -2;
96 
97 	if (rt_prio(p->prio)) /* includes deadline */
98 		return p->prio; /* [-1, 99] */
99 
100 	if (p->sched_class == &idle_sched_class)
101 		return MAX_RT_PRIO + NICE_WIDTH; /* 140 */
102 
103 	return MAX_RT_PRIO + MAX_NICE; /* 120, squash fair */
104 }
105 
106 /*
107  * l(a,b)
108  * le(a,b) := !l(b,a)
109  * g(a,b)  := l(b,a)
110  * ge(a,b) := !l(a,b)
111  */
112 
113 /* real prio, less is less */
114 static inline bool prio_less(struct task_struct *a, struct task_struct *b, bool in_fi)
115 {
116 
117 	int pa = __task_prio(a), pb = __task_prio(b);
118 
119 	if (-pa < -pb)
120 		return true;
121 
122 	if (-pb < -pa)
123 		return false;
124 
125 	if (pa == -1) /* dl_prio() doesn't work because of stop_class above */
126 		return !dl_time_before(a->dl.deadline, b->dl.deadline);
127 
128 	if (pa == MAX_RT_PRIO + MAX_NICE)	/* fair */
129 		return cfs_prio_less(a, b, in_fi);
130 
131 	return false;
132 }
133 
134 static inline bool __sched_core_less(struct task_struct *a, struct task_struct *b)
135 {
136 	if (a->core_cookie < b->core_cookie)
137 		return true;
138 
139 	if (a->core_cookie > b->core_cookie)
140 		return false;
141 
142 	/* flip prio, so high prio is leftmost */
143 	if (prio_less(b, a, task_rq(a)->core->core_forceidle))
144 		return true;
145 
146 	return false;
147 }
148 
149 #define __node_2_sc(node) rb_entry((node), struct task_struct, core_node)
150 
151 static inline bool rb_sched_core_less(struct rb_node *a, const struct rb_node *b)
152 {
153 	return __sched_core_less(__node_2_sc(a), __node_2_sc(b));
154 }
155 
156 static inline int rb_sched_core_cmp(const void *key, const struct rb_node *node)
157 {
158 	const struct task_struct *p = __node_2_sc(node);
159 	unsigned long cookie = (unsigned long)key;
160 
161 	if (cookie < p->core_cookie)
162 		return -1;
163 
164 	if (cookie > p->core_cookie)
165 		return 1;
166 
167 	return 0;
168 }
169 
170 void sched_core_enqueue(struct rq *rq, struct task_struct *p)
171 {
172 	rq->core->core_task_seq++;
173 
174 	if (!p->core_cookie)
175 		return;
176 
177 	rb_add(&p->core_node, &rq->core_tree, rb_sched_core_less);
178 }
179 
180 void sched_core_dequeue(struct rq *rq, struct task_struct *p)
181 {
182 	rq->core->core_task_seq++;
183 
184 	if (!sched_core_enqueued(p))
185 		return;
186 
187 	rb_erase(&p->core_node, &rq->core_tree);
188 	RB_CLEAR_NODE(&p->core_node);
189 }
190 
191 /*
192  * Find left-most (aka, highest priority) task matching @cookie.
193  */
194 static struct task_struct *sched_core_find(struct rq *rq, unsigned long cookie)
195 {
196 	struct rb_node *node;
197 
198 	node = rb_find_first((void *)cookie, &rq->core_tree, rb_sched_core_cmp);
199 	/*
200 	 * The idle task always matches any cookie!
201 	 */
202 	if (!node)
203 		return idle_sched_class.pick_task(rq);
204 
205 	return __node_2_sc(node);
206 }
207 
208 static struct task_struct *sched_core_next(struct task_struct *p, unsigned long cookie)
209 {
210 	struct rb_node *node = &p->core_node;
211 
212 	node = rb_next(node);
213 	if (!node)
214 		return NULL;
215 
216 	p = container_of(node, struct task_struct, core_node);
217 	if (p->core_cookie != cookie)
218 		return NULL;
219 
220 	return p;
221 }
222 
223 /*
224  * Magic required such that:
225  *
226  *	raw_spin_rq_lock(rq);
227  *	...
228  *	raw_spin_rq_unlock(rq);
229  *
230  * ends up locking and unlocking the _same_ lock, and all CPUs
231  * always agree on what rq has what lock.
232  *
233  * XXX entirely possible to selectively enable cores, don't bother for now.
234  */
235 
236 static DEFINE_MUTEX(sched_core_mutex);
237 static atomic_t sched_core_count;
238 static struct cpumask sched_core_mask;
239 
240 static void sched_core_lock(int cpu, unsigned long *flags)
241 {
242 	const struct cpumask *smt_mask = cpu_smt_mask(cpu);
243 	int t, i = 0;
244 
245 	local_irq_save(*flags);
246 	for_each_cpu(t, smt_mask)
247 		raw_spin_lock_nested(&cpu_rq(t)->__lock, i++);
248 }
249 
250 static void sched_core_unlock(int cpu, unsigned long *flags)
251 {
252 	const struct cpumask *smt_mask = cpu_smt_mask(cpu);
253 	int t;
254 
255 	for_each_cpu(t, smt_mask)
256 		raw_spin_unlock(&cpu_rq(t)->__lock);
257 	local_irq_restore(*flags);
258 }
259 
260 static void __sched_core_flip(bool enabled)
261 {
262 	unsigned long flags;
263 	int cpu, t;
264 
265 	cpus_read_lock();
266 
267 	/*
268 	 * Toggle the online cores, one by one.
269 	 */
270 	cpumask_copy(&sched_core_mask, cpu_online_mask);
271 	for_each_cpu(cpu, &sched_core_mask) {
272 		const struct cpumask *smt_mask = cpu_smt_mask(cpu);
273 
274 		sched_core_lock(cpu, &flags);
275 
276 		for_each_cpu(t, smt_mask)
277 			cpu_rq(t)->core_enabled = enabled;
278 
279 		sched_core_unlock(cpu, &flags);
280 
281 		cpumask_andnot(&sched_core_mask, &sched_core_mask, smt_mask);
282 	}
283 
284 	/*
285 	 * Toggle the offline CPUs.
286 	 */
287 	cpumask_copy(&sched_core_mask, cpu_possible_mask);
288 	cpumask_andnot(&sched_core_mask, &sched_core_mask, cpu_online_mask);
289 
290 	for_each_cpu(cpu, &sched_core_mask)
291 		cpu_rq(cpu)->core_enabled = enabled;
292 
293 	cpus_read_unlock();
294 }
295 
296 static void sched_core_assert_empty(void)
297 {
298 	int cpu;
299 
300 	for_each_possible_cpu(cpu)
301 		WARN_ON_ONCE(!RB_EMPTY_ROOT(&cpu_rq(cpu)->core_tree));
302 }
303 
304 static void __sched_core_enable(void)
305 {
306 	static_branch_enable(&__sched_core_enabled);
307 	/*
308 	 * Ensure all previous instances of raw_spin_rq_*lock() have finished
309 	 * and future ones will observe !sched_core_disabled().
310 	 */
311 	synchronize_rcu();
312 	__sched_core_flip(true);
313 	sched_core_assert_empty();
314 }
315 
316 static void __sched_core_disable(void)
317 {
318 	sched_core_assert_empty();
319 	__sched_core_flip(false);
320 	static_branch_disable(&__sched_core_enabled);
321 }
322 
323 void sched_core_get(void)
324 {
325 	if (atomic_inc_not_zero(&sched_core_count))
326 		return;
327 
328 	mutex_lock(&sched_core_mutex);
329 	if (!atomic_read(&sched_core_count))
330 		__sched_core_enable();
331 
332 	smp_mb__before_atomic();
333 	atomic_inc(&sched_core_count);
334 	mutex_unlock(&sched_core_mutex);
335 }
336 
337 static void __sched_core_put(struct work_struct *work)
338 {
339 	if (atomic_dec_and_mutex_lock(&sched_core_count, &sched_core_mutex)) {
340 		__sched_core_disable();
341 		mutex_unlock(&sched_core_mutex);
342 	}
343 }
344 
345 void sched_core_put(void)
346 {
347 	static DECLARE_WORK(_work, __sched_core_put);
348 
349 	/*
350 	 * "There can be only one"
351 	 *
352 	 * Either this is the last one, or we don't actually need to do any
353 	 * 'work'. If it is the last *again*, we rely on
354 	 * WORK_STRUCT_PENDING_BIT.
355 	 */
356 	if (!atomic_add_unless(&sched_core_count, -1, 1))
357 		schedule_work(&_work);
358 }
359 
360 #else /* !CONFIG_SCHED_CORE */
361 
362 static inline void sched_core_enqueue(struct rq *rq, struct task_struct *p) { }
363 static inline void sched_core_dequeue(struct rq *rq, struct task_struct *p) { }
364 
365 #endif /* CONFIG_SCHED_CORE */
366 
367 /*
368  * part of the period that we allow rt tasks to run in us.
369  * default: 0.95s
370  */
371 int sysctl_sched_rt_runtime = 950000;
372 
373 
374 /*
375  * Serialization rules:
376  *
377  * Lock order:
378  *
379  *   p->pi_lock
380  *     rq->lock
381  *       hrtimer_cpu_base->lock (hrtimer_start() for bandwidth controls)
382  *
383  *  rq1->lock
384  *    rq2->lock  where: rq1 < rq2
385  *
386  * Regular state:
387  *
388  * Normal scheduling state is serialized by rq->lock. __schedule() takes the
389  * local CPU's rq->lock, it optionally removes the task from the runqueue and
390  * always looks at the local rq data structures to find the most eligible task
391  * to run next.
392  *
393  * Task enqueue is also under rq->lock, possibly taken from another CPU.
394  * Wakeups from another LLC domain might use an IPI to transfer the enqueue to
395  * the local CPU to avoid bouncing the runqueue state around [ see
396  * ttwu_queue_wakelist() ]
397  *
398  * Task wakeup, specifically wakeups that involve migration, are horribly
399  * complicated to avoid having to take two rq->locks.
400  *
401  * Special state:
402  *
403  * System-calls and anything external will use task_rq_lock() which acquires
404  * both p->pi_lock and rq->lock. As a consequence the state they change is
405  * stable while holding either lock:
406  *
407  *  - sched_setaffinity()/
408  *    set_cpus_allowed_ptr():	p->cpus_ptr, p->nr_cpus_allowed
409  *  - set_user_nice():		p->se.load, p->*prio
410  *  - __sched_setscheduler():	p->sched_class, p->policy, p->*prio,
411  *				p->se.load, p->rt_priority,
412  *				p->dl.dl_{runtime, deadline, period, flags, bw, density}
413  *  - sched_setnuma():		p->numa_preferred_nid
414  *  - sched_move_task()/
415  *    cpu_cgroup_fork():	p->sched_task_group
416  *  - uclamp_update_active()	p->uclamp*
417  *
418  * p->state <- TASK_*:
419  *
420  *   is changed locklessly using set_current_state(), __set_current_state() or
421  *   set_special_state(), see their respective comments, or by
422  *   try_to_wake_up(). This latter uses p->pi_lock to serialize against
423  *   concurrent self.
424  *
425  * p->on_rq <- { 0, 1 = TASK_ON_RQ_QUEUED, 2 = TASK_ON_RQ_MIGRATING }:
426  *
427  *   is set by activate_task() and cleared by deactivate_task(), under
428  *   rq->lock. Non-zero indicates the task is runnable, the special
429  *   ON_RQ_MIGRATING state is used for migration without holding both
430  *   rq->locks. It indicates task_cpu() is not stable, see task_rq_lock().
431  *
432  * p->on_cpu <- { 0, 1 }:
433  *
434  *   is set by prepare_task() and cleared by finish_task() such that it will be
435  *   set before p is scheduled-in and cleared after p is scheduled-out, both
436  *   under rq->lock. Non-zero indicates the task is running on its CPU.
437  *
438  *   [ The astute reader will observe that it is possible for two tasks on one
439  *     CPU to have ->on_cpu = 1 at the same time. ]
440  *
441  * task_cpu(p): is changed by set_task_cpu(), the rules are:
442  *
443  *  - Don't call set_task_cpu() on a blocked task:
444  *
445  *    We don't care what CPU we're not running on, this simplifies hotplug,
446  *    the CPU assignment of blocked tasks isn't required to be valid.
447  *
448  *  - for try_to_wake_up(), called under p->pi_lock:
449  *
450  *    This allows try_to_wake_up() to only take one rq->lock, see its comment.
451  *
452  *  - for migration called under rq->lock:
453  *    [ see task_on_rq_migrating() in task_rq_lock() ]
454  *
455  *    o move_queued_task()
456  *    o detach_task()
457  *
458  *  - for migration called under double_rq_lock():
459  *
460  *    o __migrate_swap_task()
461  *    o push_rt_task() / pull_rt_task()
462  *    o push_dl_task() / pull_dl_task()
463  *    o dl_task_offline_migration()
464  *
465  */
466 
467 void raw_spin_rq_lock_nested(struct rq *rq, int subclass)
468 {
469 	raw_spinlock_t *lock;
470 
471 	/* Matches synchronize_rcu() in __sched_core_enable() */
472 	preempt_disable();
473 	if (sched_core_disabled()) {
474 		raw_spin_lock_nested(&rq->__lock, subclass);
475 		/* preempt_count *MUST* be > 1 */
476 		preempt_enable_no_resched();
477 		return;
478 	}
479 
480 	for (;;) {
481 		lock = __rq_lockp(rq);
482 		raw_spin_lock_nested(lock, subclass);
483 		if (likely(lock == __rq_lockp(rq))) {
484 			/* preempt_count *MUST* be > 1 */
485 			preempt_enable_no_resched();
486 			return;
487 		}
488 		raw_spin_unlock(lock);
489 	}
490 }
491 
492 bool raw_spin_rq_trylock(struct rq *rq)
493 {
494 	raw_spinlock_t *lock;
495 	bool ret;
496 
497 	/* Matches synchronize_rcu() in __sched_core_enable() */
498 	preempt_disable();
499 	if (sched_core_disabled()) {
500 		ret = raw_spin_trylock(&rq->__lock);
501 		preempt_enable();
502 		return ret;
503 	}
504 
505 	for (;;) {
506 		lock = __rq_lockp(rq);
507 		ret = raw_spin_trylock(lock);
508 		if (!ret || (likely(lock == __rq_lockp(rq)))) {
509 			preempt_enable();
510 			return ret;
511 		}
512 		raw_spin_unlock(lock);
513 	}
514 }
515 
516 void raw_spin_rq_unlock(struct rq *rq)
517 {
518 	raw_spin_unlock(rq_lockp(rq));
519 }
520 
521 #ifdef CONFIG_SMP
522 /*
523  * double_rq_lock - safely lock two runqueues
524  */
525 void double_rq_lock(struct rq *rq1, struct rq *rq2)
526 {
527 	lockdep_assert_irqs_disabled();
528 
529 	if (rq_order_less(rq2, rq1))
530 		swap(rq1, rq2);
531 
532 	raw_spin_rq_lock(rq1);
533 	if (__rq_lockp(rq1) == __rq_lockp(rq2))
534 		return;
535 
536 	raw_spin_rq_lock_nested(rq2, SINGLE_DEPTH_NESTING);
537 }
538 #endif
539 
540 /*
541  * __task_rq_lock - lock the rq @p resides on.
542  */
543 struct rq *__task_rq_lock(struct task_struct *p, struct rq_flags *rf)
544 	__acquires(rq->lock)
545 {
546 	struct rq *rq;
547 
548 	lockdep_assert_held(&p->pi_lock);
549 
550 	for (;;) {
551 		rq = task_rq(p);
552 		raw_spin_rq_lock(rq);
553 		if (likely(rq == task_rq(p) && !task_on_rq_migrating(p))) {
554 			rq_pin_lock(rq, rf);
555 			return rq;
556 		}
557 		raw_spin_rq_unlock(rq);
558 
559 		while (unlikely(task_on_rq_migrating(p)))
560 			cpu_relax();
561 	}
562 }
563 
564 /*
565  * task_rq_lock - lock p->pi_lock and lock the rq @p resides on.
566  */
567 struct rq *task_rq_lock(struct task_struct *p, struct rq_flags *rf)
568 	__acquires(p->pi_lock)
569 	__acquires(rq->lock)
570 {
571 	struct rq *rq;
572 
573 	for (;;) {
574 		raw_spin_lock_irqsave(&p->pi_lock, rf->flags);
575 		rq = task_rq(p);
576 		raw_spin_rq_lock(rq);
577 		/*
578 		 *	move_queued_task()		task_rq_lock()
579 		 *
580 		 *	ACQUIRE (rq->lock)
581 		 *	[S] ->on_rq = MIGRATING		[L] rq = task_rq()
582 		 *	WMB (__set_task_cpu())		ACQUIRE (rq->lock);
583 		 *	[S] ->cpu = new_cpu		[L] task_rq()
584 		 *					[L] ->on_rq
585 		 *	RELEASE (rq->lock)
586 		 *
587 		 * If we observe the old CPU in task_rq_lock(), the acquire of
588 		 * the old rq->lock will fully serialize against the stores.
589 		 *
590 		 * If we observe the new CPU in task_rq_lock(), the address
591 		 * dependency headed by '[L] rq = task_rq()' and the acquire
592 		 * will pair with the WMB to ensure we then also see migrating.
593 		 */
594 		if (likely(rq == task_rq(p) && !task_on_rq_migrating(p))) {
595 			rq_pin_lock(rq, rf);
596 			return rq;
597 		}
598 		raw_spin_rq_unlock(rq);
599 		raw_spin_unlock_irqrestore(&p->pi_lock, rf->flags);
600 
601 		while (unlikely(task_on_rq_migrating(p)))
602 			cpu_relax();
603 	}
604 }
605 
606 /*
607  * RQ-clock updating methods:
608  */
609 
610 static void update_rq_clock_task(struct rq *rq, s64 delta)
611 {
612 /*
613  * In theory, the compile should just see 0 here, and optimize out the call
614  * to sched_rt_avg_update. But I don't trust it...
615  */
616 	s64 __maybe_unused steal = 0, irq_delta = 0;
617 
618 #ifdef CONFIG_IRQ_TIME_ACCOUNTING
619 	irq_delta = irq_time_read(cpu_of(rq)) - rq->prev_irq_time;
620 
621 	/*
622 	 * Since irq_time is only updated on {soft,}irq_exit, we might run into
623 	 * this case when a previous update_rq_clock() happened inside a
624 	 * {soft,}irq region.
625 	 *
626 	 * When this happens, we stop ->clock_task and only update the
627 	 * prev_irq_time stamp to account for the part that fit, so that a next
628 	 * update will consume the rest. This ensures ->clock_task is
629 	 * monotonic.
630 	 *
631 	 * It does however cause some slight miss-attribution of {soft,}irq
632 	 * time, a more accurate solution would be to update the irq_time using
633 	 * the current rq->clock timestamp, except that would require using
634 	 * atomic ops.
635 	 */
636 	if (irq_delta > delta)
637 		irq_delta = delta;
638 
639 	rq->prev_irq_time += irq_delta;
640 	delta -= irq_delta;
641 #endif
642 #ifdef CONFIG_PARAVIRT_TIME_ACCOUNTING
643 	if (static_key_false((&paravirt_steal_rq_enabled))) {
644 		steal = paravirt_steal_clock(cpu_of(rq));
645 		steal -= rq->prev_steal_time_rq;
646 
647 		if (unlikely(steal > delta))
648 			steal = delta;
649 
650 		rq->prev_steal_time_rq += steal;
651 		delta -= steal;
652 	}
653 #endif
654 
655 	rq->clock_task += delta;
656 
657 #ifdef CONFIG_HAVE_SCHED_AVG_IRQ
658 	if ((irq_delta + steal) && sched_feat(NONTASK_CAPACITY))
659 		update_irq_load_avg(rq, irq_delta + steal);
660 #endif
661 	update_rq_clock_pelt(rq, delta);
662 }
663 
664 void update_rq_clock(struct rq *rq)
665 {
666 	s64 delta;
667 
668 	lockdep_assert_rq_held(rq);
669 
670 	if (rq->clock_update_flags & RQCF_ACT_SKIP)
671 		return;
672 
673 #ifdef CONFIG_SCHED_DEBUG
674 	if (sched_feat(WARN_DOUBLE_CLOCK))
675 		SCHED_WARN_ON(rq->clock_update_flags & RQCF_UPDATED);
676 	rq->clock_update_flags |= RQCF_UPDATED;
677 #endif
678 
679 	delta = sched_clock_cpu(cpu_of(rq)) - rq->clock;
680 	if (delta < 0)
681 		return;
682 	rq->clock += delta;
683 	update_rq_clock_task(rq, delta);
684 }
685 
686 #ifdef CONFIG_SCHED_HRTICK
687 /*
688  * Use HR-timers to deliver accurate preemption points.
689  */
690 
691 static void hrtick_clear(struct rq *rq)
692 {
693 	if (hrtimer_active(&rq->hrtick_timer))
694 		hrtimer_cancel(&rq->hrtick_timer);
695 }
696 
697 /*
698  * High-resolution timer tick.
699  * Runs from hardirq context with interrupts disabled.
700  */
701 static enum hrtimer_restart hrtick(struct hrtimer *timer)
702 {
703 	struct rq *rq = container_of(timer, struct rq, hrtick_timer);
704 	struct rq_flags rf;
705 
706 	WARN_ON_ONCE(cpu_of(rq) != smp_processor_id());
707 
708 	rq_lock(rq, &rf);
709 	update_rq_clock(rq);
710 	rq->curr->sched_class->task_tick(rq, rq->curr, 1);
711 	rq_unlock(rq, &rf);
712 
713 	return HRTIMER_NORESTART;
714 }
715 
716 #ifdef CONFIG_SMP
717 
718 static void __hrtick_restart(struct rq *rq)
719 {
720 	struct hrtimer *timer = &rq->hrtick_timer;
721 	ktime_t time = rq->hrtick_time;
722 
723 	hrtimer_start(timer, time, HRTIMER_MODE_ABS_PINNED_HARD);
724 }
725 
726 /*
727  * called from hardirq (IPI) context
728  */
729 static void __hrtick_start(void *arg)
730 {
731 	struct rq *rq = arg;
732 	struct rq_flags rf;
733 
734 	rq_lock(rq, &rf);
735 	__hrtick_restart(rq);
736 	rq_unlock(rq, &rf);
737 }
738 
739 /*
740  * Called to set the hrtick timer state.
741  *
742  * called with rq->lock held and irqs disabled
743  */
744 void hrtick_start(struct rq *rq, u64 delay)
745 {
746 	struct hrtimer *timer = &rq->hrtick_timer;
747 	s64 delta;
748 
749 	/*
750 	 * Don't schedule slices shorter than 10000ns, that just
751 	 * doesn't make sense and can cause timer DoS.
752 	 */
753 	delta = max_t(s64, delay, 10000LL);
754 	rq->hrtick_time = ktime_add_ns(timer->base->get_time(), delta);
755 
756 	if (rq == this_rq())
757 		__hrtick_restart(rq);
758 	else
759 		smp_call_function_single_async(cpu_of(rq), &rq->hrtick_csd);
760 }
761 
762 #else
763 /*
764  * Called to set the hrtick timer state.
765  *
766  * called with rq->lock held and irqs disabled
767  */
768 void hrtick_start(struct rq *rq, u64 delay)
769 {
770 	/*
771 	 * Don't schedule slices shorter than 10000ns, that just
772 	 * doesn't make sense. Rely on vruntime for fairness.
773 	 */
774 	delay = max_t(u64, delay, 10000LL);
775 	hrtimer_start(&rq->hrtick_timer, ns_to_ktime(delay),
776 		      HRTIMER_MODE_REL_PINNED_HARD);
777 }
778 
779 #endif /* CONFIG_SMP */
780 
781 static void hrtick_rq_init(struct rq *rq)
782 {
783 #ifdef CONFIG_SMP
784 	INIT_CSD(&rq->hrtick_csd, __hrtick_start, rq);
785 #endif
786 	hrtimer_init(&rq->hrtick_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL_HARD);
787 	rq->hrtick_timer.function = hrtick;
788 }
789 #else	/* CONFIG_SCHED_HRTICK */
790 static inline void hrtick_clear(struct rq *rq)
791 {
792 }
793 
794 static inline void hrtick_rq_init(struct rq *rq)
795 {
796 }
797 #endif	/* CONFIG_SCHED_HRTICK */
798 
799 /*
800  * cmpxchg based fetch_or, macro so it works for different integer types
801  */
802 #define fetch_or(ptr, mask)						\
803 	({								\
804 		typeof(ptr) _ptr = (ptr);				\
805 		typeof(mask) _mask = (mask);				\
806 		typeof(*_ptr) _old, _val = *_ptr;			\
807 									\
808 		for (;;) {						\
809 			_old = cmpxchg(_ptr, _val, _val | _mask);	\
810 			if (_old == _val)				\
811 				break;					\
812 			_val = _old;					\
813 		}							\
814 	_old;								\
815 })
816 
817 #if defined(CONFIG_SMP) && defined(TIF_POLLING_NRFLAG)
818 /*
819  * Atomically set TIF_NEED_RESCHED and test for TIF_POLLING_NRFLAG,
820  * this avoids any races wrt polling state changes and thereby avoids
821  * spurious IPIs.
822  */
823 static bool set_nr_and_not_polling(struct task_struct *p)
824 {
825 	struct thread_info *ti = task_thread_info(p);
826 	return !(fetch_or(&ti->flags, _TIF_NEED_RESCHED) & _TIF_POLLING_NRFLAG);
827 }
828 
829 /*
830  * Atomically set TIF_NEED_RESCHED if TIF_POLLING_NRFLAG is set.
831  *
832  * If this returns true, then the idle task promises to call
833  * sched_ttwu_pending() and reschedule soon.
834  */
835 static bool set_nr_if_polling(struct task_struct *p)
836 {
837 	struct thread_info *ti = task_thread_info(p);
838 	typeof(ti->flags) old, val = READ_ONCE(ti->flags);
839 
840 	for (;;) {
841 		if (!(val & _TIF_POLLING_NRFLAG))
842 			return false;
843 		if (val & _TIF_NEED_RESCHED)
844 			return true;
845 		old = cmpxchg(&ti->flags, val, val | _TIF_NEED_RESCHED);
846 		if (old == val)
847 			break;
848 		val = old;
849 	}
850 	return true;
851 }
852 
853 #else
854 static bool set_nr_and_not_polling(struct task_struct *p)
855 {
856 	set_tsk_need_resched(p);
857 	return true;
858 }
859 
860 #ifdef CONFIG_SMP
861 static bool set_nr_if_polling(struct task_struct *p)
862 {
863 	return false;
864 }
865 #endif
866 #endif
867 
868 static bool __wake_q_add(struct wake_q_head *head, struct task_struct *task)
869 {
870 	struct wake_q_node *node = &task->wake_q;
871 
872 	/*
873 	 * Atomically grab the task, if ->wake_q is !nil already it means
874 	 * it's already queued (either by us or someone else) and will get the
875 	 * wakeup due to that.
876 	 *
877 	 * In order to ensure that a pending wakeup will observe our pending
878 	 * state, even in the failed case, an explicit smp_mb() must be used.
879 	 */
880 	smp_mb__before_atomic();
881 	if (unlikely(cmpxchg_relaxed(&node->next, NULL, WAKE_Q_TAIL)))
882 		return false;
883 
884 	/*
885 	 * The head is context local, there can be no concurrency.
886 	 */
887 	*head->lastp = node;
888 	head->lastp = &node->next;
889 	return true;
890 }
891 
892 /**
893  * wake_q_add() - queue a wakeup for 'later' waking.
894  * @head: the wake_q_head to add @task to
895  * @task: the task to queue for 'later' wakeup
896  *
897  * Queue a task for later wakeup, most likely by the wake_up_q() call in the
898  * same context, _HOWEVER_ this is not guaranteed, the wakeup can come
899  * instantly.
900  *
901  * This function must be used as-if it were wake_up_process(); IOW the task
902  * must be ready to be woken at this location.
903  */
904 void wake_q_add(struct wake_q_head *head, struct task_struct *task)
905 {
906 	if (__wake_q_add(head, task))
907 		get_task_struct(task);
908 }
909 
910 /**
911  * wake_q_add_safe() - safely queue a wakeup for 'later' waking.
912  * @head: the wake_q_head to add @task to
913  * @task: the task to queue for 'later' wakeup
914  *
915  * Queue a task for later wakeup, most likely by the wake_up_q() call in the
916  * same context, _HOWEVER_ this is not guaranteed, the wakeup can come
917  * instantly.
918  *
919  * This function must be used as-if it were wake_up_process(); IOW the task
920  * must be ready to be woken at this location.
921  *
922  * This function is essentially a task-safe equivalent to wake_q_add(). Callers
923  * that already hold reference to @task can call the 'safe' version and trust
924  * wake_q to do the right thing depending whether or not the @task is already
925  * queued for wakeup.
926  */
927 void wake_q_add_safe(struct wake_q_head *head, struct task_struct *task)
928 {
929 	if (!__wake_q_add(head, task))
930 		put_task_struct(task);
931 }
932 
933 void wake_up_q(struct wake_q_head *head)
934 {
935 	struct wake_q_node *node = head->first;
936 
937 	while (node != WAKE_Q_TAIL) {
938 		struct task_struct *task;
939 
940 		task = container_of(node, struct task_struct, wake_q);
941 		/* Task can safely be re-inserted now: */
942 		node = node->next;
943 		task->wake_q.next = NULL;
944 
945 		/*
946 		 * wake_up_process() executes a full barrier, which pairs with
947 		 * the queueing in wake_q_add() so as not to miss wakeups.
948 		 */
949 		wake_up_process(task);
950 		put_task_struct(task);
951 	}
952 }
953 
954 /*
955  * resched_curr - mark rq's current task 'to be rescheduled now'.
956  *
957  * On UP this means the setting of the need_resched flag, on SMP it
958  * might also involve a cross-CPU call to trigger the scheduler on
959  * the target CPU.
960  */
961 void resched_curr(struct rq *rq)
962 {
963 	struct task_struct *curr = rq->curr;
964 	int cpu;
965 
966 	lockdep_assert_rq_held(rq);
967 
968 	if (test_tsk_need_resched(curr))
969 		return;
970 
971 	cpu = cpu_of(rq);
972 
973 	if (cpu == smp_processor_id()) {
974 		set_tsk_need_resched(curr);
975 		set_preempt_need_resched();
976 		return;
977 	}
978 
979 	if (set_nr_and_not_polling(curr))
980 		smp_send_reschedule(cpu);
981 	else
982 		trace_sched_wake_idle_without_ipi(cpu);
983 }
984 
985 void resched_cpu(int cpu)
986 {
987 	struct rq *rq = cpu_rq(cpu);
988 	unsigned long flags;
989 
990 	raw_spin_rq_lock_irqsave(rq, flags);
991 	if (cpu_online(cpu) || cpu == smp_processor_id())
992 		resched_curr(rq);
993 	raw_spin_rq_unlock_irqrestore(rq, flags);
994 }
995 
996 #ifdef CONFIG_SMP
997 #ifdef CONFIG_NO_HZ_COMMON
998 /*
999  * In the semi idle case, use the nearest busy CPU for migrating timers
1000  * from an idle CPU.  This is good for power-savings.
1001  *
1002  * We don't do similar optimization for completely idle system, as
1003  * selecting an idle CPU will add more delays to the timers than intended
1004  * (as that CPU's timer base may not be uptodate wrt jiffies etc).
1005  */
1006 int get_nohz_timer_target(void)
1007 {
1008 	int i, cpu = smp_processor_id(), default_cpu = -1;
1009 	struct sched_domain *sd;
1010 
1011 	if (housekeeping_cpu(cpu, HK_FLAG_TIMER)) {
1012 		if (!idle_cpu(cpu))
1013 			return cpu;
1014 		default_cpu = cpu;
1015 	}
1016 
1017 	rcu_read_lock();
1018 	for_each_domain(cpu, sd) {
1019 		for_each_cpu_and(i, sched_domain_span(sd),
1020 			housekeeping_cpumask(HK_FLAG_TIMER)) {
1021 			if (cpu == i)
1022 				continue;
1023 
1024 			if (!idle_cpu(i)) {
1025 				cpu = i;
1026 				goto unlock;
1027 			}
1028 		}
1029 	}
1030 
1031 	if (default_cpu == -1)
1032 		default_cpu = housekeeping_any_cpu(HK_FLAG_TIMER);
1033 	cpu = default_cpu;
1034 unlock:
1035 	rcu_read_unlock();
1036 	return cpu;
1037 }
1038 
1039 /*
1040  * When add_timer_on() enqueues a timer into the timer wheel of an
1041  * idle CPU then this timer might expire before the next timer event
1042  * which is scheduled to wake up that CPU. In case of a completely
1043  * idle system the next event might even be infinite time into the
1044  * future. wake_up_idle_cpu() ensures that the CPU is woken up and
1045  * leaves the inner idle loop so the newly added timer is taken into
1046  * account when the CPU goes back to idle and evaluates the timer
1047  * wheel for the next timer event.
1048  */
1049 static void wake_up_idle_cpu(int cpu)
1050 {
1051 	struct rq *rq = cpu_rq(cpu);
1052 
1053 	if (cpu == smp_processor_id())
1054 		return;
1055 
1056 	if (set_nr_and_not_polling(rq->idle))
1057 		smp_send_reschedule(cpu);
1058 	else
1059 		trace_sched_wake_idle_without_ipi(cpu);
1060 }
1061 
1062 static bool wake_up_full_nohz_cpu(int cpu)
1063 {
1064 	/*
1065 	 * We just need the target to call irq_exit() and re-evaluate
1066 	 * the next tick. The nohz full kick at least implies that.
1067 	 * If needed we can still optimize that later with an
1068 	 * empty IRQ.
1069 	 */
1070 	if (cpu_is_offline(cpu))
1071 		return true;  /* Don't try to wake offline CPUs. */
1072 	if (tick_nohz_full_cpu(cpu)) {
1073 		if (cpu != smp_processor_id() ||
1074 		    tick_nohz_tick_stopped())
1075 			tick_nohz_full_kick_cpu(cpu);
1076 		return true;
1077 	}
1078 
1079 	return false;
1080 }
1081 
1082 /*
1083  * Wake up the specified CPU.  If the CPU is going offline, it is the
1084  * caller's responsibility to deal with the lost wakeup, for example,
1085  * by hooking into the CPU_DEAD notifier like timers and hrtimers do.
1086  */
1087 void wake_up_nohz_cpu(int cpu)
1088 {
1089 	if (!wake_up_full_nohz_cpu(cpu))
1090 		wake_up_idle_cpu(cpu);
1091 }
1092 
1093 static void nohz_csd_func(void *info)
1094 {
1095 	struct rq *rq = info;
1096 	int cpu = cpu_of(rq);
1097 	unsigned int flags;
1098 
1099 	/*
1100 	 * Release the rq::nohz_csd.
1101 	 */
1102 	flags = atomic_fetch_andnot(NOHZ_KICK_MASK | NOHZ_NEWILB_KICK, nohz_flags(cpu));
1103 	WARN_ON(!(flags & NOHZ_KICK_MASK));
1104 
1105 	rq->idle_balance = idle_cpu(cpu);
1106 	if (rq->idle_balance && !need_resched()) {
1107 		rq->nohz_idle_balance = flags;
1108 		raise_softirq_irqoff(SCHED_SOFTIRQ);
1109 	}
1110 }
1111 
1112 #endif /* CONFIG_NO_HZ_COMMON */
1113 
1114 #ifdef CONFIG_NO_HZ_FULL
1115 bool sched_can_stop_tick(struct rq *rq)
1116 {
1117 	int fifo_nr_running;
1118 
1119 	/* Deadline tasks, even if single, need the tick */
1120 	if (rq->dl.dl_nr_running)
1121 		return false;
1122 
1123 	/*
1124 	 * If there are more than one RR tasks, we need the tick to affect the
1125 	 * actual RR behaviour.
1126 	 */
1127 	if (rq->rt.rr_nr_running) {
1128 		if (rq->rt.rr_nr_running == 1)
1129 			return true;
1130 		else
1131 			return false;
1132 	}
1133 
1134 	/*
1135 	 * If there's no RR tasks, but FIFO tasks, we can skip the tick, no
1136 	 * forced preemption between FIFO tasks.
1137 	 */
1138 	fifo_nr_running = rq->rt.rt_nr_running - rq->rt.rr_nr_running;
1139 	if (fifo_nr_running)
1140 		return true;
1141 
1142 	/*
1143 	 * If there are no DL,RR/FIFO tasks, there must only be CFS tasks left;
1144 	 * if there's more than one we need the tick for involuntary
1145 	 * preemption.
1146 	 */
1147 	if (rq->nr_running > 1)
1148 		return false;
1149 
1150 	return true;
1151 }
1152 #endif /* CONFIG_NO_HZ_FULL */
1153 #endif /* CONFIG_SMP */
1154 
1155 #if defined(CONFIG_RT_GROUP_SCHED) || (defined(CONFIG_FAIR_GROUP_SCHED) && \
1156 			(defined(CONFIG_SMP) || defined(CONFIG_CFS_BANDWIDTH)))
1157 /*
1158  * Iterate task_group tree rooted at *from, calling @down when first entering a
1159  * node and @up when leaving it for the final time.
1160  *
1161  * Caller must hold rcu_lock or sufficient equivalent.
1162  */
1163 int walk_tg_tree_from(struct task_group *from,
1164 			     tg_visitor down, tg_visitor up, void *data)
1165 {
1166 	struct task_group *parent, *child;
1167 	int ret;
1168 
1169 	parent = from;
1170 
1171 down:
1172 	ret = (*down)(parent, data);
1173 	if (ret)
1174 		goto out;
1175 	list_for_each_entry_rcu(child, &parent->children, siblings) {
1176 		parent = child;
1177 		goto down;
1178 
1179 up:
1180 		continue;
1181 	}
1182 	ret = (*up)(parent, data);
1183 	if (ret || parent == from)
1184 		goto out;
1185 
1186 	child = parent;
1187 	parent = parent->parent;
1188 	if (parent)
1189 		goto up;
1190 out:
1191 	return ret;
1192 }
1193 
1194 int tg_nop(struct task_group *tg, void *data)
1195 {
1196 	return 0;
1197 }
1198 #endif
1199 
1200 static void set_load_weight(struct task_struct *p, bool update_load)
1201 {
1202 	int prio = p->static_prio - MAX_RT_PRIO;
1203 	struct load_weight *load = &p->se.load;
1204 
1205 	/*
1206 	 * SCHED_IDLE tasks get minimal weight:
1207 	 */
1208 	if (task_has_idle_policy(p)) {
1209 		load->weight = scale_load(WEIGHT_IDLEPRIO);
1210 		load->inv_weight = WMULT_IDLEPRIO;
1211 		return;
1212 	}
1213 
1214 	/*
1215 	 * SCHED_OTHER tasks have to update their load when changing their
1216 	 * weight
1217 	 */
1218 	if (update_load && p->sched_class == &fair_sched_class) {
1219 		reweight_task(p, prio);
1220 	} else {
1221 		load->weight = scale_load(sched_prio_to_weight[prio]);
1222 		load->inv_weight = sched_prio_to_wmult[prio];
1223 	}
1224 }
1225 
1226 #ifdef CONFIG_UCLAMP_TASK
1227 /*
1228  * Serializes updates of utilization clamp values
1229  *
1230  * The (slow-path) user-space triggers utilization clamp value updates which
1231  * can require updates on (fast-path) scheduler's data structures used to
1232  * support enqueue/dequeue operations.
1233  * While the per-CPU rq lock protects fast-path update operations, user-space
1234  * requests are serialized using a mutex to reduce the risk of conflicting
1235  * updates or API abuses.
1236  */
1237 static DEFINE_MUTEX(uclamp_mutex);
1238 
1239 /* Max allowed minimum utilization */
1240 unsigned int sysctl_sched_uclamp_util_min = SCHED_CAPACITY_SCALE;
1241 
1242 /* Max allowed maximum utilization */
1243 unsigned int sysctl_sched_uclamp_util_max = SCHED_CAPACITY_SCALE;
1244 
1245 /*
1246  * By default RT tasks run at the maximum performance point/capacity of the
1247  * system. Uclamp enforces this by always setting UCLAMP_MIN of RT tasks to
1248  * SCHED_CAPACITY_SCALE.
1249  *
1250  * This knob allows admins to change the default behavior when uclamp is being
1251  * used. In battery powered devices, particularly, running at the maximum
1252  * capacity and frequency will increase energy consumption and shorten the
1253  * battery life.
1254  *
1255  * This knob only affects RT tasks that their uclamp_se->user_defined == false.
1256  *
1257  * This knob will not override the system default sched_util_clamp_min defined
1258  * above.
1259  */
1260 unsigned int sysctl_sched_uclamp_util_min_rt_default = SCHED_CAPACITY_SCALE;
1261 
1262 /* All clamps are required to be less or equal than these values */
1263 static struct uclamp_se uclamp_default[UCLAMP_CNT];
1264 
1265 /*
1266  * This static key is used to reduce the uclamp overhead in the fast path. It
1267  * primarily disables the call to uclamp_rq_{inc, dec}() in
1268  * enqueue/dequeue_task().
1269  *
1270  * This allows users to continue to enable uclamp in their kernel config with
1271  * minimum uclamp overhead in the fast path.
1272  *
1273  * As soon as userspace modifies any of the uclamp knobs, the static key is
1274  * enabled, since we have an actual users that make use of uclamp
1275  * functionality.
1276  *
1277  * The knobs that would enable this static key are:
1278  *
1279  *   * A task modifying its uclamp value with sched_setattr().
1280  *   * An admin modifying the sysctl_sched_uclamp_{min, max} via procfs.
1281  *   * An admin modifying the cgroup cpu.uclamp.{min, max}
1282  */
1283 DEFINE_STATIC_KEY_FALSE(sched_uclamp_used);
1284 
1285 /* Integer rounded range for each bucket */
1286 #define UCLAMP_BUCKET_DELTA DIV_ROUND_CLOSEST(SCHED_CAPACITY_SCALE, UCLAMP_BUCKETS)
1287 
1288 #define for_each_clamp_id(clamp_id) \
1289 	for ((clamp_id) = 0; (clamp_id) < UCLAMP_CNT; (clamp_id)++)
1290 
1291 static inline unsigned int uclamp_bucket_id(unsigned int clamp_value)
1292 {
1293 	return min_t(unsigned int, clamp_value / UCLAMP_BUCKET_DELTA, UCLAMP_BUCKETS - 1);
1294 }
1295 
1296 static inline unsigned int uclamp_none(enum uclamp_id clamp_id)
1297 {
1298 	if (clamp_id == UCLAMP_MIN)
1299 		return 0;
1300 	return SCHED_CAPACITY_SCALE;
1301 }
1302 
1303 static inline void uclamp_se_set(struct uclamp_se *uc_se,
1304 				 unsigned int value, bool user_defined)
1305 {
1306 	uc_se->value = value;
1307 	uc_se->bucket_id = uclamp_bucket_id(value);
1308 	uc_se->user_defined = user_defined;
1309 }
1310 
1311 static inline unsigned int
1312 uclamp_idle_value(struct rq *rq, enum uclamp_id clamp_id,
1313 		  unsigned int clamp_value)
1314 {
1315 	/*
1316 	 * Avoid blocked utilization pushing up the frequency when we go
1317 	 * idle (which drops the max-clamp) by retaining the last known
1318 	 * max-clamp.
1319 	 */
1320 	if (clamp_id == UCLAMP_MAX) {
1321 		rq->uclamp_flags |= UCLAMP_FLAG_IDLE;
1322 		return clamp_value;
1323 	}
1324 
1325 	return uclamp_none(UCLAMP_MIN);
1326 }
1327 
1328 static inline void uclamp_idle_reset(struct rq *rq, enum uclamp_id clamp_id,
1329 				     unsigned int clamp_value)
1330 {
1331 	/* Reset max-clamp retention only on idle exit */
1332 	if (!(rq->uclamp_flags & UCLAMP_FLAG_IDLE))
1333 		return;
1334 
1335 	WRITE_ONCE(rq->uclamp[clamp_id].value, clamp_value);
1336 }
1337 
1338 static inline
1339 unsigned int uclamp_rq_max_value(struct rq *rq, enum uclamp_id clamp_id,
1340 				   unsigned int clamp_value)
1341 {
1342 	struct uclamp_bucket *bucket = rq->uclamp[clamp_id].bucket;
1343 	int bucket_id = UCLAMP_BUCKETS - 1;
1344 
1345 	/*
1346 	 * Since both min and max clamps are max aggregated, find the
1347 	 * top most bucket with tasks in.
1348 	 */
1349 	for ( ; bucket_id >= 0; bucket_id--) {
1350 		if (!bucket[bucket_id].tasks)
1351 			continue;
1352 		return bucket[bucket_id].value;
1353 	}
1354 
1355 	/* No tasks -- default clamp values */
1356 	return uclamp_idle_value(rq, clamp_id, clamp_value);
1357 }
1358 
1359 static void __uclamp_update_util_min_rt_default(struct task_struct *p)
1360 {
1361 	unsigned int default_util_min;
1362 	struct uclamp_se *uc_se;
1363 
1364 	lockdep_assert_held(&p->pi_lock);
1365 
1366 	uc_se = &p->uclamp_req[UCLAMP_MIN];
1367 
1368 	/* Only sync if user didn't override the default */
1369 	if (uc_se->user_defined)
1370 		return;
1371 
1372 	default_util_min = sysctl_sched_uclamp_util_min_rt_default;
1373 	uclamp_se_set(uc_se, default_util_min, false);
1374 }
1375 
1376 static void uclamp_update_util_min_rt_default(struct task_struct *p)
1377 {
1378 	struct rq_flags rf;
1379 	struct rq *rq;
1380 
1381 	if (!rt_task(p))
1382 		return;
1383 
1384 	/* Protect updates to p->uclamp_* */
1385 	rq = task_rq_lock(p, &rf);
1386 	__uclamp_update_util_min_rt_default(p);
1387 	task_rq_unlock(rq, p, &rf);
1388 }
1389 
1390 static void uclamp_sync_util_min_rt_default(void)
1391 {
1392 	struct task_struct *g, *p;
1393 
1394 	/*
1395 	 * copy_process()			sysctl_uclamp
1396 	 *					  uclamp_min_rt = X;
1397 	 *   write_lock(&tasklist_lock)		  read_lock(&tasklist_lock)
1398 	 *   // link thread			  smp_mb__after_spinlock()
1399 	 *   write_unlock(&tasklist_lock)	  read_unlock(&tasklist_lock);
1400 	 *   sched_post_fork()			  for_each_process_thread()
1401 	 *     __uclamp_sync_rt()		    __uclamp_sync_rt()
1402 	 *
1403 	 * Ensures that either sched_post_fork() will observe the new
1404 	 * uclamp_min_rt or for_each_process_thread() will observe the new
1405 	 * task.
1406 	 */
1407 	read_lock(&tasklist_lock);
1408 	smp_mb__after_spinlock();
1409 	read_unlock(&tasklist_lock);
1410 
1411 	rcu_read_lock();
1412 	for_each_process_thread(g, p)
1413 		uclamp_update_util_min_rt_default(p);
1414 	rcu_read_unlock();
1415 }
1416 
1417 static inline struct uclamp_se
1418 uclamp_tg_restrict(struct task_struct *p, enum uclamp_id clamp_id)
1419 {
1420 	/* Copy by value as we could modify it */
1421 	struct uclamp_se uc_req = p->uclamp_req[clamp_id];
1422 #ifdef CONFIG_UCLAMP_TASK_GROUP
1423 	unsigned int tg_min, tg_max, value;
1424 
1425 	/*
1426 	 * Tasks in autogroups or root task group will be
1427 	 * restricted by system defaults.
1428 	 */
1429 	if (task_group_is_autogroup(task_group(p)))
1430 		return uc_req;
1431 	if (task_group(p) == &root_task_group)
1432 		return uc_req;
1433 
1434 	tg_min = task_group(p)->uclamp[UCLAMP_MIN].value;
1435 	tg_max = task_group(p)->uclamp[UCLAMP_MAX].value;
1436 	value = uc_req.value;
1437 	value = clamp(value, tg_min, tg_max);
1438 	uclamp_se_set(&uc_req, value, false);
1439 #endif
1440 
1441 	return uc_req;
1442 }
1443 
1444 /*
1445  * The effective clamp bucket index of a task depends on, by increasing
1446  * priority:
1447  * - the task specific clamp value, when explicitly requested from userspace
1448  * - the task group effective clamp value, for tasks not either in the root
1449  *   group or in an autogroup
1450  * - the system default clamp value, defined by the sysadmin
1451  */
1452 static inline struct uclamp_se
1453 uclamp_eff_get(struct task_struct *p, enum uclamp_id clamp_id)
1454 {
1455 	struct uclamp_se uc_req = uclamp_tg_restrict(p, clamp_id);
1456 	struct uclamp_se uc_max = uclamp_default[clamp_id];
1457 
1458 	/* System default restrictions always apply */
1459 	if (unlikely(uc_req.value > uc_max.value))
1460 		return uc_max;
1461 
1462 	return uc_req;
1463 }
1464 
1465 unsigned long uclamp_eff_value(struct task_struct *p, enum uclamp_id clamp_id)
1466 {
1467 	struct uclamp_se uc_eff;
1468 
1469 	/* Task currently refcounted: use back-annotated (effective) value */
1470 	if (p->uclamp[clamp_id].active)
1471 		return (unsigned long)p->uclamp[clamp_id].value;
1472 
1473 	uc_eff = uclamp_eff_get(p, clamp_id);
1474 
1475 	return (unsigned long)uc_eff.value;
1476 }
1477 
1478 /*
1479  * When a task is enqueued on a rq, the clamp bucket currently defined by the
1480  * task's uclamp::bucket_id is refcounted on that rq. This also immediately
1481  * updates the rq's clamp value if required.
1482  *
1483  * Tasks can have a task-specific value requested from user-space, track
1484  * within each bucket the maximum value for tasks refcounted in it.
1485  * This "local max aggregation" allows to track the exact "requested" value
1486  * for each bucket when all its RUNNABLE tasks require the same clamp.
1487  */
1488 static inline void uclamp_rq_inc_id(struct rq *rq, struct task_struct *p,
1489 				    enum uclamp_id clamp_id)
1490 {
1491 	struct uclamp_rq *uc_rq = &rq->uclamp[clamp_id];
1492 	struct uclamp_se *uc_se = &p->uclamp[clamp_id];
1493 	struct uclamp_bucket *bucket;
1494 
1495 	lockdep_assert_rq_held(rq);
1496 
1497 	/* Update task effective clamp */
1498 	p->uclamp[clamp_id] = uclamp_eff_get(p, clamp_id);
1499 
1500 	bucket = &uc_rq->bucket[uc_se->bucket_id];
1501 	bucket->tasks++;
1502 	uc_se->active = true;
1503 
1504 	uclamp_idle_reset(rq, clamp_id, uc_se->value);
1505 
1506 	/*
1507 	 * Local max aggregation: rq buckets always track the max
1508 	 * "requested" clamp value of its RUNNABLE tasks.
1509 	 */
1510 	if (bucket->tasks == 1 || uc_se->value > bucket->value)
1511 		bucket->value = uc_se->value;
1512 
1513 	if (uc_se->value > READ_ONCE(uc_rq->value))
1514 		WRITE_ONCE(uc_rq->value, uc_se->value);
1515 }
1516 
1517 /*
1518  * When a task is dequeued from a rq, the clamp bucket refcounted by the task
1519  * is released. If this is the last task reference counting the rq's max
1520  * active clamp value, then the rq's clamp value is updated.
1521  *
1522  * Both refcounted tasks and rq's cached clamp values are expected to be
1523  * always valid. If it's detected they are not, as defensive programming,
1524  * enforce the expected state and warn.
1525  */
1526 static inline void uclamp_rq_dec_id(struct rq *rq, struct task_struct *p,
1527 				    enum uclamp_id clamp_id)
1528 {
1529 	struct uclamp_rq *uc_rq = &rq->uclamp[clamp_id];
1530 	struct uclamp_se *uc_se = &p->uclamp[clamp_id];
1531 	struct uclamp_bucket *bucket;
1532 	unsigned int bkt_clamp;
1533 	unsigned int rq_clamp;
1534 
1535 	lockdep_assert_rq_held(rq);
1536 
1537 	/*
1538 	 * If sched_uclamp_used was enabled after task @p was enqueued,
1539 	 * we could end up with unbalanced call to uclamp_rq_dec_id().
1540 	 *
1541 	 * In this case the uc_se->active flag should be false since no uclamp
1542 	 * accounting was performed at enqueue time and we can just return
1543 	 * here.
1544 	 *
1545 	 * Need to be careful of the following enqueue/dequeue ordering
1546 	 * problem too
1547 	 *
1548 	 *	enqueue(taskA)
1549 	 *	// sched_uclamp_used gets enabled
1550 	 *	enqueue(taskB)
1551 	 *	dequeue(taskA)
1552 	 *	// Must not decrement bucket->tasks here
1553 	 *	dequeue(taskB)
1554 	 *
1555 	 * where we could end up with stale data in uc_se and
1556 	 * bucket[uc_se->bucket_id].
1557 	 *
1558 	 * The following check here eliminates the possibility of such race.
1559 	 */
1560 	if (unlikely(!uc_se->active))
1561 		return;
1562 
1563 	bucket = &uc_rq->bucket[uc_se->bucket_id];
1564 
1565 	SCHED_WARN_ON(!bucket->tasks);
1566 	if (likely(bucket->tasks))
1567 		bucket->tasks--;
1568 
1569 	uc_se->active = false;
1570 
1571 	/*
1572 	 * Keep "local max aggregation" simple and accept to (possibly)
1573 	 * overboost some RUNNABLE tasks in the same bucket.
1574 	 * The rq clamp bucket value is reset to its base value whenever
1575 	 * there are no more RUNNABLE tasks refcounting it.
1576 	 */
1577 	if (likely(bucket->tasks))
1578 		return;
1579 
1580 	rq_clamp = READ_ONCE(uc_rq->value);
1581 	/*
1582 	 * Defensive programming: this should never happen. If it happens,
1583 	 * e.g. due to future modification, warn and fixup the expected value.
1584 	 */
1585 	SCHED_WARN_ON(bucket->value > rq_clamp);
1586 	if (bucket->value >= rq_clamp) {
1587 		bkt_clamp = uclamp_rq_max_value(rq, clamp_id, uc_se->value);
1588 		WRITE_ONCE(uc_rq->value, bkt_clamp);
1589 	}
1590 }
1591 
1592 static inline void uclamp_rq_inc(struct rq *rq, struct task_struct *p)
1593 {
1594 	enum uclamp_id clamp_id;
1595 
1596 	/*
1597 	 * Avoid any overhead until uclamp is actually used by the userspace.
1598 	 *
1599 	 * The condition is constructed such that a NOP is generated when
1600 	 * sched_uclamp_used is disabled.
1601 	 */
1602 	if (!static_branch_unlikely(&sched_uclamp_used))
1603 		return;
1604 
1605 	if (unlikely(!p->sched_class->uclamp_enabled))
1606 		return;
1607 
1608 	for_each_clamp_id(clamp_id)
1609 		uclamp_rq_inc_id(rq, p, clamp_id);
1610 
1611 	/* Reset clamp idle holding when there is one RUNNABLE task */
1612 	if (rq->uclamp_flags & UCLAMP_FLAG_IDLE)
1613 		rq->uclamp_flags &= ~UCLAMP_FLAG_IDLE;
1614 }
1615 
1616 static inline void uclamp_rq_dec(struct rq *rq, struct task_struct *p)
1617 {
1618 	enum uclamp_id clamp_id;
1619 
1620 	/*
1621 	 * Avoid any overhead until uclamp is actually used by the userspace.
1622 	 *
1623 	 * The condition is constructed such that a NOP is generated when
1624 	 * sched_uclamp_used is disabled.
1625 	 */
1626 	if (!static_branch_unlikely(&sched_uclamp_used))
1627 		return;
1628 
1629 	if (unlikely(!p->sched_class->uclamp_enabled))
1630 		return;
1631 
1632 	for_each_clamp_id(clamp_id)
1633 		uclamp_rq_dec_id(rq, p, clamp_id);
1634 }
1635 
1636 static inline void
1637 uclamp_update_active(struct task_struct *p)
1638 {
1639 	enum uclamp_id clamp_id;
1640 	struct rq_flags rf;
1641 	struct rq *rq;
1642 
1643 	/*
1644 	 * Lock the task and the rq where the task is (or was) queued.
1645 	 *
1646 	 * We might lock the (previous) rq of a !RUNNABLE task, but that's the
1647 	 * price to pay to safely serialize util_{min,max} updates with
1648 	 * enqueues, dequeues and migration operations.
1649 	 * This is the same locking schema used by __set_cpus_allowed_ptr().
1650 	 */
1651 	rq = task_rq_lock(p, &rf);
1652 
1653 	/*
1654 	 * Setting the clamp bucket is serialized by task_rq_lock().
1655 	 * If the task is not yet RUNNABLE and its task_struct is not
1656 	 * affecting a valid clamp bucket, the next time it's enqueued,
1657 	 * it will already see the updated clamp bucket value.
1658 	 */
1659 	for_each_clamp_id(clamp_id) {
1660 		if (p->uclamp[clamp_id].active) {
1661 			uclamp_rq_dec_id(rq, p, clamp_id);
1662 			uclamp_rq_inc_id(rq, p, clamp_id);
1663 		}
1664 	}
1665 
1666 	task_rq_unlock(rq, p, &rf);
1667 }
1668 
1669 #ifdef CONFIG_UCLAMP_TASK_GROUP
1670 static inline void
1671 uclamp_update_active_tasks(struct cgroup_subsys_state *css)
1672 {
1673 	struct css_task_iter it;
1674 	struct task_struct *p;
1675 
1676 	css_task_iter_start(css, 0, &it);
1677 	while ((p = css_task_iter_next(&it)))
1678 		uclamp_update_active(p);
1679 	css_task_iter_end(&it);
1680 }
1681 
1682 static void cpu_util_update_eff(struct cgroup_subsys_state *css);
1683 static void uclamp_update_root_tg(void)
1684 {
1685 	struct task_group *tg = &root_task_group;
1686 
1687 	uclamp_se_set(&tg->uclamp_req[UCLAMP_MIN],
1688 		      sysctl_sched_uclamp_util_min, false);
1689 	uclamp_se_set(&tg->uclamp_req[UCLAMP_MAX],
1690 		      sysctl_sched_uclamp_util_max, false);
1691 
1692 	rcu_read_lock();
1693 	cpu_util_update_eff(&root_task_group.css);
1694 	rcu_read_unlock();
1695 }
1696 #else
1697 static void uclamp_update_root_tg(void) { }
1698 #endif
1699 
1700 int sysctl_sched_uclamp_handler(struct ctl_table *table, int write,
1701 				void *buffer, size_t *lenp, loff_t *ppos)
1702 {
1703 	bool update_root_tg = false;
1704 	int old_min, old_max, old_min_rt;
1705 	int result;
1706 
1707 	mutex_lock(&uclamp_mutex);
1708 	old_min = sysctl_sched_uclamp_util_min;
1709 	old_max = sysctl_sched_uclamp_util_max;
1710 	old_min_rt = sysctl_sched_uclamp_util_min_rt_default;
1711 
1712 	result = proc_dointvec(table, write, buffer, lenp, ppos);
1713 	if (result)
1714 		goto undo;
1715 	if (!write)
1716 		goto done;
1717 
1718 	if (sysctl_sched_uclamp_util_min > sysctl_sched_uclamp_util_max ||
1719 	    sysctl_sched_uclamp_util_max > SCHED_CAPACITY_SCALE	||
1720 	    sysctl_sched_uclamp_util_min_rt_default > SCHED_CAPACITY_SCALE) {
1721 
1722 		result = -EINVAL;
1723 		goto undo;
1724 	}
1725 
1726 	if (old_min != sysctl_sched_uclamp_util_min) {
1727 		uclamp_se_set(&uclamp_default[UCLAMP_MIN],
1728 			      sysctl_sched_uclamp_util_min, false);
1729 		update_root_tg = true;
1730 	}
1731 	if (old_max != sysctl_sched_uclamp_util_max) {
1732 		uclamp_se_set(&uclamp_default[UCLAMP_MAX],
1733 			      sysctl_sched_uclamp_util_max, false);
1734 		update_root_tg = true;
1735 	}
1736 
1737 	if (update_root_tg) {
1738 		static_branch_enable(&sched_uclamp_used);
1739 		uclamp_update_root_tg();
1740 	}
1741 
1742 	if (old_min_rt != sysctl_sched_uclamp_util_min_rt_default) {
1743 		static_branch_enable(&sched_uclamp_used);
1744 		uclamp_sync_util_min_rt_default();
1745 	}
1746 
1747 	/*
1748 	 * We update all RUNNABLE tasks only when task groups are in use.
1749 	 * Otherwise, keep it simple and do just a lazy update at each next
1750 	 * task enqueue time.
1751 	 */
1752 
1753 	goto done;
1754 
1755 undo:
1756 	sysctl_sched_uclamp_util_min = old_min;
1757 	sysctl_sched_uclamp_util_max = old_max;
1758 	sysctl_sched_uclamp_util_min_rt_default = old_min_rt;
1759 done:
1760 	mutex_unlock(&uclamp_mutex);
1761 
1762 	return result;
1763 }
1764 
1765 static int uclamp_validate(struct task_struct *p,
1766 			   const struct sched_attr *attr)
1767 {
1768 	int util_min = p->uclamp_req[UCLAMP_MIN].value;
1769 	int util_max = p->uclamp_req[UCLAMP_MAX].value;
1770 
1771 	if (attr->sched_flags & SCHED_FLAG_UTIL_CLAMP_MIN) {
1772 		util_min = attr->sched_util_min;
1773 
1774 		if (util_min + 1 > SCHED_CAPACITY_SCALE + 1)
1775 			return -EINVAL;
1776 	}
1777 
1778 	if (attr->sched_flags & SCHED_FLAG_UTIL_CLAMP_MAX) {
1779 		util_max = attr->sched_util_max;
1780 
1781 		if (util_max + 1 > SCHED_CAPACITY_SCALE + 1)
1782 			return -EINVAL;
1783 	}
1784 
1785 	if (util_min != -1 && util_max != -1 && util_min > util_max)
1786 		return -EINVAL;
1787 
1788 	/*
1789 	 * We have valid uclamp attributes; make sure uclamp is enabled.
1790 	 *
1791 	 * We need to do that here, because enabling static branches is a
1792 	 * blocking operation which obviously cannot be done while holding
1793 	 * scheduler locks.
1794 	 */
1795 	static_branch_enable(&sched_uclamp_used);
1796 
1797 	return 0;
1798 }
1799 
1800 static bool uclamp_reset(const struct sched_attr *attr,
1801 			 enum uclamp_id clamp_id,
1802 			 struct uclamp_se *uc_se)
1803 {
1804 	/* Reset on sched class change for a non user-defined clamp value. */
1805 	if (likely(!(attr->sched_flags & SCHED_FLAG_UTIL_CLAMP)) &&
1806 	    !uc_se->user_defined)
1807 		return true;
1808 
1809 	/* Reset on sched_util_{min,max} == -1. */
1810 	if (clamp_id == UCLAMP_MIN &&
1811 	    attr->sched_flags & SCHED_FLAG_UTIL_CLAMP_MIN &&
1812 	    attr->sched_util_min == -1) {
1813 		return true;
1814 	}
1815 
1816 	if (clamp_id == UCLAMP_MAX &&
1817 	    attr->sched_flags & SCHED_FLAG_UTIL_CLAMP_MAX &&
1818 	    attr->sched_util_max == -1) {
1819 		return true;
1820 	}
1821 
1822 	return false;
1823 }
1824 
1825 static void __setscheduler_uclamp(struct task_struct *p,
1826 				  const struct sched_attr *attr)
1827 {
1828 	enum uclamp_id clamp_id;
1829 
1830 	for_each_clamp_id(clamp_id) {
1831 		struct uclamp_se *uc_se = &p->uclamp_req[clamp_id];
1832 		unsigned int value;
1833 
1834 		if (!uclamp_reset(attr, clamp_id, uc_se))
1835 			continue;
1836 
1837 		/*
1838 		 * RT by default have a 100% boost value that could be modified
1839 		 * at runtime.
1840 		 */
1841 		if (unlikely(rt_task(p) && clamp_id == UCLAMP_MIN))
1842 			value = sysctl_sched_uclamp_util_min_rt_default;
1843 		else
1844 			value = uclamp_none(clamp_id);
1845 
1846 		uclamp_se_set(uc_se, value, false);
1847 
1848 	}
1849 
1850 	if (likely(!(attr->sched_flags & SCHED_FLAG_UTIL_CLAMP)))
1851 		return;
1852 
1853 	if (attr->sched_flags & SCHED_FLAG_UTIL_CLAMP_MIN &&
1854 	    attr->sched_util_min != -1) {
1855 		uclamp_se_set(&p->uclamp_req[UCLAMP_MIN],
1856 			      attr->sched_util_min, true);
1857 	}
1858 
1859 	if (attr->sched_flags & SCHED_FLAG_UTIL_CLAMP_MAX &&
1860 	    attr->sched_util_max != -1) {
1861 		uclamp_se_set(&p->uclamp_req[UCLAMP_MAX],
1862 			      attr->sched_util_max, true);
1863 	}
1864 }
1865 
1866 static void uclamp_fork(struct task_struct *p)
1867 {
1868 	enum uclamp_id clamp_id;
1869 
1870 	/*
1871 	 * We don't need to hold task_rq_lock() when updating p->uclamp_* here
1872 	 * as the task is still at its early fork stages.
1873 	 */
1874 	for_each_clamp_id(clamp_id)
1875 		p->uclamp[clamp_id].active = false;
1876 
1877 	if (likely(!p->sched_reset_on_fork))
1878 		return;
1879 
1880 	for_each_clamp_id(clamp_id) {
1881 		uclamp_se_set(&p->uclamp_req[clamp_id],
1882 			      uclamp_none(clamp_id), false);
1883 	}
1884 }
1885 
1886 static void uclamp_post_fork(struct task_struct *p)
1887 {
1888 	uclamp_update_util_min_rt_default(p);
1889 }
1890 
1891 static void __init init_uclamp_rq(struct rq *rq)
1892 {
1893 	enum uclamp_id clamp_id;
1894 	struct uclamp_rq *uc_rq = rq->uclamp;
1895 
1896 	for_each_clamp_id(clamp_id) {
1897 		uc_rq[clamp_id] = (struct uclamp_rq) {
1898 			.value = uclamp_none(clamp_id)
1899 		};
1900 	}
1901 
1902 	rq->uclamp_flags = 0;
1903 }
1904 
1905 static void __init init_uclamp(void)
1906 {
1907 	struct uclamp_se uc_max = {};
1908 	enum uclamp_id clamp_id;
1909 	int cpu;
1910 
1911 	for_each_possible_cpu(cpu)
1912 		init_uclamp_rq(cpu_rq(cpu));
1913 
1914 	for_each_clamp_id(clamp_id) {
1915 		uclamp_se_set(&init_task.uclamp_req[clamp_id],
1916 			      uclamp_none(clamp_id), false);
1917 	}
1918 
1919 	/* System defaults allow max clamp values for both indexes */
1920 	uclamp_se_set(&uc_max, uclamp_none(UCLAMP_MAX), false);
1921 	for_each_clamp_id(clamp_id) {
1922 		uclamp_default[clamp_id] = uc_max;
1923 #ifdef CONFIG_UCLAMP_TASK_GROUP
1924 		root_task_group.uclamp_req[clamp_id] = uc_max;
1925 		root_task_group.uclamp[clamp_id] = uc_max;
1926 #endif
1927 	}
1928 }
1929 
1930 #else /* CONFIG_UCLAMP_TASK */
1931 static inline void uclamp_rq_inc(struct rq *rq, struct task_struct *p) { }
1932 static inline void uclamp_rq_dec(struct rq *rq, struct task_struct *p) { }
1933 static inline int uclamp_validate(struct task_struct *p,
1934 				  const struct sched_attr *attr)
1935 {
1936 	return -EOPNOTSUPP;
1937 }
1938 static void __setscheduler_uclamp(struct task_struct *p,
1939 				  const struct sched_attr *attr) { }
1940 static inline void uclamp_fork(struct task_struct *p) { }
1941 static inline void uclamp_post_fork(struct task_struct *p) { }
1942 static inline void init_uclamp(void) { }
1943 #endif /* CONFIG_UCLAMP_TASK */
1944 
1945 bool sched_task_on_rq(struct task_struct *p)
1946 {
1947 	return task_on_rq_queued(p);
1948 }
1949 
1950 static inline void enqueue_task(struct rq *rq, struct task_struct *p, int flags)
1951 {
1952 	if (!(flags & ENQUEUE_NOCLOCK))
1953 		update_rq_clock(rq);
1954 
1955 	if (!(flags & ENQUEUE_RESTORE)) {
1956 		sched_info_enqueue(rq, p);
1957 		psi_enqueue(p, flags & ENQUEUE_WAKEUP);
1958 	}
1959 
1960 	uclamp_rq_inc(rq, p);
1961 	p->sched_class->enqueue_task(rq, p, flags);
1962 
1963 	if (sched_core_enabled(rq))
1964 		sched_core_enqueue(rq, p);
1965 }
1966 
1967 static inline void dequeue_task(struct rq *rq, struct task_struct *p, int flags)
1968 {
1969 	if (sched_core_enabled(rq))
1970 		sched_core_dequeue(rq, p);
1971 
1972 	if (!(flags & DEQUEUE_NOCLOCK))
1973 		update_rq_clock(rq);
1974 
1975 	if (!(flags & DEQUEUE_SAVE)) {
1976 		sched_info_dequeue(rq, p);
1977 		psi_dequeue(p, flags & DEQUEUE_SLEEP);
1978 	}
1979 
1980 	uclamp_rq_dec(rq, p);
1981 	p->sched_class->dequeue_task(rq, p, flags);
1982 }
1983 
1984 void activate_task(struct rq *rq, struct task_struct *p, int flags)
1985 {
1986 	enqueue_task(rq, p, flags);
1987 
1988 	p->on_rq = TASK_ON_RQ_QUEUED;
1989 }
1990 
1991 void deactivate_task(struct rq *rq, struct task_struct *p, int flags)
1992 {
1993 	p->on_rq = (flags & DEQUEUE_SLEEP) ? 0 : TASK_ON_RQ_MIGRATING;
1994 
1995 	dequeue_task(rq, p, flags);
1996 }
1997 
1998 static inline int __normal_prio(int policy, int rt_prio, int nice)
1999 {
2000 	int prio;
2001 
2002 	if (dl_policy(policy))
2003 		prio = MAX_DL_PRIO - 1;
2004 	else if (rt_policy(policy))
2005 		prio = MAX_RT_PRIO - 1 - rt_prio;
2006 	else
2007 		prio = NICE_TO_PRIO(nice);
2008 
2009 	return prio;
2010 }
2011 
2012 /*
2013  * Calculate the expected normal priority: i.e. priority
2014  * without taking RT-inheritance into account. Might be
2015  * boosted by interactivity modifiers. Changes upon fork,
2016  * setprio syscalls, and whenever the interactivity
2017  * estimator recalculates.
2018  */
2019 static inline int normal_prio(struct task_struct *p)
2020 {
2021 	return __normal_prio(p->policy, p->rt_priority, PRIO_TO_NICE(p->static_prio));
2022 }
2023 
2024 /*
2025  * Calculate the current priority, i.e. the priority
2026  * taken into account by the scheduler. This value might
2027  * be boosted by RT tasks, or might be boosted by
2028  * interactivity modifiers. Will be RT if the task got
2029  * RT-boosted. If not then it returns p->normal_prio.
2030  */
2031 static int effective_prio(struct task_struct *p)
2032 {
2033 	p->normal_prio = normal_prio(p);
2034 	/*
2035 	 * If we are RT tasks or we were boosted to RT priority,
2036 	 * keep the priority unchanged. Otherwise, update priority
2037 	 * to the normal priority:
2038 	 */
2039 	if (!rt_prio(p->prio))
2040 		return p->normal_prio;
2041 	return p->prio;
2042 }
2043 
2044 /**
2045  * task_curr - is this task currently executing on a CPU?
2046  * @p: the task in question.
2047  *
2048  * Return: 1 if the task is currently executing. 0 otherwise.
2049  */
2050 inline int task_curr(const struct task_struct *p)
2051 {
2052 	return cpu_curr(task_cpu(p)) == p;
2053 }
2054 
2055 /*
2056  * switched_from, switched_to and prio_changed must _NOT_ drop rq->lock,
2057  * use the balance_callback list if you want balancing.
2058  *
2059  * this means any call to check_class_changed() must be followed by a call to
2060  * balance_callback().
2061  */
2062 static inline void check_class_changed(struct rq *rq, struct task_struct *p,
2063 				       const struct sched_class *prev_class,
2064 				       int oldprio)
2065 {
2066 	if (prev_class != p->sched_class) {
2067 		if (prev_class->switched_from)
2068 			prev_class->switched_from(rq, p);
2069 
2070 		p->sched_class->switched_to(rq, p);
2071 	} else if (oldprio != p->prio || dl_task(p))
2072 		p->sched_class->prio_changed(rq, p, oldprio);
2073 }
2074 
2075 void check_preempt_curr(struct rq *rq, struct task_struct *p, int flags)
2076 {
2077 	if (p->sched_class == rq->curr->sched_class)
2078 		rq->curr->sched_class->check_preempt_curr(rq, p, flags);
2079 	else if (p->sched_class > rq->curr->sched_class)
2080 		resched_curr(rq);
2081 
2082 	/*
2083 	 * A queue event has occurred, and we're going to schedule.  In
2084 	 * this case, we can save a useless back to back clock update.
2085 	 */
2086 	if (task_on_rq_queued(rq->curr) && test_tsk_need_resched(rq->curr))
2087 		rq_clock_skip_update(rq);
2088 }
2089 
2090 #ifdef CONFIG_SMP
2091 
2092 static void
2093 __do_set_cpus_allowed(struct task_struct *p, const struct cpumask *new_mask, u32 flags);
2094 
2095 static int __set_cpus_allowed_ptr(struct task_struct *p,
2096 				  const struct cpumask *new_mask,
2097 				  u32 flags);
2098 
2099 static void migrate_disable_switch(struct rq *rq, struct task_struct *p)
2100 {
2101 	if (likely(!p->migration_disabled))
2102 		return;
2103 
2104 	if (p->cpus_ptr != &p->cpus_mask)
2105 		return;
2106 
2107 	/*
2108 	 * Violates locking rules! see comment in __do_set_cpus_allowed().
2109 	 */
2110 	__do_set_cpus_allowed(p, cpumask_of(rq->cpu), SCA_MIGRATE_DISABLE);
2111 }
2112 
2113 void migrate_disable(void)
2114 {
2115 	struct task_struct *p = current;
2116 
2117 	if (p->migration_disabled) {
2118 		p->migration_disabled++;
2119 		return;
2120 	}
2121 
2122 	preempt_disable();
2123 	this_rq()->nr_pinned++;
2124 	p->migration_disabled = 1;
2125 	preempt_enable();
2126 }
2127 EXPORT_SYMBOL_GPL(migrate_disable);
2128 
2129 void migrate_enable(void)
2130 {
2131 	struct task_struct *p = current;
2132 
2133 	if (p->migration_disabled > 1) {
2134 		p->migration_disabled--;
2135 		return;
2136 	}
2137 
2138 	/*
2139 	 * Ensure stop_task runs either before or after this, and that
2140 	 * __set_cpus_allowed_ptr(SCA_MIGRATE_ENABLE) doesn't schedule().
2141 	 */
2142 	preempt_disable();
2143 	if (p->cpus_ptr != &p->cpus_mask)
2144 		__set_cpus_allowed_ptr(p, &p->cpus_mask, SCA_MIGRATE_ENABLE);
2145 	/*
2146 	 * Mustn't clear migration_disabled() until cpus_ptr points back at the
2147 	 * regular cpus_mask, otherwise things that race (eg.
2148 	 * select_fallback_rq) get confused.
2149 	 */
2150 	barrier();
2151 	p->migration_disabled = 0;
2152 	this_rq()->nr_pinned--;
2153 	preempt_enable();
2154 }
2155 EXPORT_SYMBOL_GPL(migrate_enable);
2156 
2157 static inline bool rq_has_pinned_tasks(struct rq *rq)
2158 {
2159 	return rq->nr_pinned;
2160 }
2161 
2162 /*
2163  * Per-CPU kthreads are allowed to run on !active && online CPUs, see
2164  * __set_cpus_allowed_ptr() and select_fallback_rq().
2165  */
2166 static inline bool is_cpu_allowed(struct task_struct *p, int cpu)
2167 {
2168 	/* When not in the task's cpumask, no point in looking further. */
2169 	if (!cpumask_test_cpu(cpu, p->cpus_ptr))
2170 		return false;
2171 
2172 	/* migrate_disabled() must be allowed to finish. */
2173 	if (is_migration_disabled(p))
2174 		return cpu_online(cpu);
2175 
2176 	/* Non kernel threads are not allowed during either online or offline. */
2177 	if (!(p->flags & PF_KTHREAD))
2178 		return cpu_active(cpu);
2179 
2180 	/* KTHREAD_IS_PER_CPU is always allowed. */
2181 	if (kthread_is_per_cpu(p))
2182 		return cpu_online(cpu);
2183 
2184 	/* Regular kernel threads don't get to stay during offline. */
2185 	if (cpu_dying(cpu))
2186 		return false;
2187 
2188 	/* But are allowed during online. */
2189 	return cpu_online(cpu);
2190 }
2191 
2192 /*
2193  * This is how migration works:
2194  *
2195  * 1) we invoke migration_cpu_stop() on the target CPU using
2196  *    stop_one_cpu().
2197  * 2) stopper starts to run (implicitly forcing the migrated thread
2198  *    off the CPU)
2199  * 3) it checks whether the migrated task is still in the wrong runqueue.
2200  * 4) if it's in the wrong runqueue then the migration thread removes
2201  *    it and puts it into the right queue.
2202  * 5) stopper completes and stop_one_cpu() returns and the migration
2203  *    is done.
2204  */
2205 
2206 /*
2207  * move_queued_task - move a queued task to new rq.
2208  *
2209  * Returns (locked) new rq. Old rq's lock is released.
2210  */
2211 static struct rq *move_queued_task(struct rq *rq, struct rq_flags *rf,
2212 				   struct task_struct *p, int new_cpu)
2213 {
2214 	lockdep_assert_rq_held(rq);
2215 
2216 	deactivate_task(rq, p, DEQUEUE_NOCLOCK);
2217 	set_task_cpu(p, new_cpu);
2218 	rq_unlock(rq, rf);
2219 
2220 	rq = cpu_rq(new_cpu);
2221 
2222 	rq_lock(rq, rf);
2223 	BUG_ON(task_cpu(p) != new_cpu);
2224 	activate_task(rq, p, 0);
2225 	check_preempt_curr(rq, p, 0);
2226 
2227 	return rq;
2228 }
2229 
2230 struct migration_arg {
2231 	struct task_struct		*task;
2232 	int				dest_cpu;
2233 	struct set_affinity_pending	*pending;
2234 };
2235 
2236 /*
2237  * @refs: number of wait_for_completion()
2238  * @stop_pending: is @stop_work in use
2239  */
2240 struct set_affinity_pending {
2241 	refcount_t		refs;
2242 	unsigned int		stop_pending;
2243 	struct completion	done;
2244 	struct cpu_stop_work	stop_work;
2245 	struct migration_arg	arg;
2246 };
2247 
2248 /*
2249  * Move (not current) task off this CPU, onto the destination CPU. We're doing
2250  * this because either it can't run here any more (set_cpus_allowed()
2251  * away from this CPU, or CPU going down), or because we're
2252  * attempting to rebalance this task on exec (sched_exec).
2253  *
2254  * So we race with normal scheduler movements, but that's OK, as long
2255  * as the task is no longer on this CPU.
2256  */
2257 static struct rq *__migrate_task(struct rq *rq, struct rq_flags *rf,
2258 				 struct task_struct *p, int dest_cpu)
2259 {
2260 	/* Affinity changed (again). */
2261 	if (!is_cpu_allowed(p, dest_cpu))
2262 		return rq;
2263 
2264 	update_rq_clock(rq);
2265 	rq = move_queued_task(rq, rf, p, dest_cpu);
2266 
2267 	return rq;
2268 }
2269 
2270 /*
2271  * migration_cpu_stop - this will be executed by a highprio stopper thread
2272  * and performs thread migration by bumping thread off CPU then
2273  * 'pushing' onto another runqueue.
2274  */
2275 static int migration_cpu_stop(void *data)
2276 {
2277 	struct migration_arg *arg = data;
2278 	struct set_affinity_pending *pending = arg->pending;
2279 	struct task_struct *p = arg->task;
2280 	struct rq *rq = this_rq();
2281 	bool complete = false;
2282 	struct rq_flags rf;
2283 
2284 	/*
2285 	 * The original target CPU might have gone down and we might
2286 	 * be on another CPU but it doesn't matter.
2287 	 */
2288 	local_irq_save(rf.flags);
2289 	/*
2290 	 * We need to explicitly wake pending tasks before running
2291 	 * __migrate_task() such that we will not miss enforcing cpus_ptr
2292 	 * during wakeups, see set_cpus_allowed_ptr()'s TASK_WAKING test.
2293 	 */
2294 	flush_smp_call_function_from_idle();
2295 
2296 	raw_spin_lock(&p->pi_lock);
2297 	rq_lock(rq, &rf);
2298 
2299 	/*
2300 	 * If we were passed a pending, then ->stop_pending was set, thus
2301 	 * p->migration_pending must have remained stable.
2302 	 */
2303 	WARN_ON_ONCE(pending && pending != p->migration_pending);
2304 
2305 	/*
2306 	 * If task_rq(p) != rq, it cannot be migrated here, because we're
2307 	 * holding rq->lock, if p->on_rq == 0 it cannot get enqueued because
2308 	 * we're holding p->pi_lock.
2309 	 */
2310 	if (task_rq(p) == rq) {
2311 		if (is_migration_disabled(p))
2312 			goto out;
2313 
2314 		if (pending) {
2315 			p->migration_pending = NULL;
2316 			complete = true;
2317 
2318 			if (cpumask_test_cpu(task_cpu(p), &p->cpus_mask))
2319 				goto out;
2320 		}
2321 
2322 		if (task_on_rq_queued(p))
2323 			rq = __migrate_task(rq, &rf, p, arg->dest_cpu);
2324 		else
2325 			p->wake_cpu = arg->dest_cpu;
2326 
2327 		/*
2328 		 * XXX __migrate_task() can fail, at which point we might end
2329 		 * up running on a dodgy CPU, AFAICT this can only happen
2330 		 * during CPU hotplug, at which point we'll get pushed out
2331 		 * anyway, so it's probably not a big deal.
2332 		 */
2333 
2334 	} else if (pending) {
2335 		/*
2336 		 * This happens when we get migrated between migrate_enable()'s
2337 		 * preempt_enable() and scheduling the stopper task. At that
2338 		 * point we're a regular task again and not current anymore.
2339 		 *
2340 		 * A !PREEMPT kernel has a giant hole here, which makes it far
2341 		 * more likely.
2342 		 */
2343 
2344 		/*
2345 		 * The task moved before the stopper got to run. We're holding
2346 		 * ->pi_lock, so the allowed mask is stable - if it got
2347 		 * somewhere allowed, we're done.
2348 		 */
2349 		if (cpumask_test_cpu(task_cpu(p), p->cpus_ptr)) {
2350 			p->migration_pending = NULL;
2351 			complete = true;
2352 			goto out;
2353 		}
2354 
2355 		/*
2356 		 * When migrate_enable() hits a rq mis-match we can't reliably
2357 		 * determine is_migration_disabled() and so have to chase after
2358 		 * it.
2359 		 */
2360 		WARN_ON_ONCE(!pending->stop_pending);
2361 		task_rq_unlock(rq, p, &rf);
2362 		stop_one_cpu_nowait(task_cpu(p), migration_cpu_stop,
2363 				    &pending->arg, &pending->stop_work);
2364 		return 0;
2365 	}
2366 out:
2367 	if (pending)
2368 		pending->stop_pending = false;
2369 	task_rq_unlock(rq, p, &rf);
2370 
2371 	if (complete)
2372 		complete_all(&pending->done);
2373 
2374 	return 0;
2375 }
2376 
2377 int push_cpu_stop(void *arg)
2378 {
2379 	struct rq *lowest_rq = NULL, *rq = this_rq();
2380 	struct task_struct *p = arg;
2381 
2382 	raw_spin_lock_irq(&p->pi_lock);
2383 	raw_spin_rq_lock(rq);
2384 
2385 	if (task_rq(p) != rq)
2386 		goto out_unlock;
2387 
2388 	if (is_migration_disabled(p)) {
2389 		p->migration_flags |= MDF_PUSH;
2390 		goto out_unlock;
2391 	}
2392 
2393 	p->migration_flags &= ~MDF_PUSH;
2394 
2395 	if (p->sched_class->find_lock_rq)
2396 		lowest_rq = p->sched_class->find_lock_rq(p, rq);
2397 
2398 	if (!lowest_rq)
2399 		goto out_unlock;
2400 
2401 	// XXX validate p is still the highest prio task
2402 	if (task_rq(p) == rq) {
2403 		deactivate_task(rq, p, 0);
2404 		set_task_cpu(p, lowest_rq->cpu);
2405 		activate_task(lowest_rq, p, 0);
2406 		resched_curr(lowest_rq);
2407 	}
2408 
2409 	double_unlock_balance(rq, lowest_rq);
2410 
2411 out_unlock:
2412 	rq->push_busy = false;
2413 	raw_spin_rq_unlock(rq);
2414 	raw_spin_unlock_irq(&p->pi_lock);
2415 
2416 	put_task_struct(p);
2417 	return 0;
2418 }
2419 
2420 /*
2421  * sched_class::set_cpus_allowed must do the below, but is not required to
2422  * actually call this function.
2423  */
2424 void set_cpus_allowed_common(struct task_struct *p, const struct cpumask *new_mask, u32 flags)
2425 {
2426 	if (flags & (SCA_MIGRATE_ENABLE | SCA_MIGRATE_DISABLE)) {
2427 		p->cpus_ptr = new_mask;
2428 		return;
2429 	}
2430 
2431 	cpumask_copy(&p->cpus_mask, new_mask);
2432 	p->nr_cpus_allowed = cpumask_weight(new_mask);
2433 }
2434 
2435 static void
2436 __do_set_cpus_allowed(struct task_struct *p, const struct cpumask *new_mask, u32 flags)
2437 {
2438 	struct rq *rq = task_rq(p);
2439 	bool queued, running;
2440 
2441 	/*
2442 	 * This here violates the locking rules for affinity, since we're only
2443 	 * supposed to change these variables while holding both rq->lock and
2444 	 * p->pi_lock.
2445 	 *
2446 	 * HOWEVER, it magically works, because ttwu() is the only code that
2447 	 * accesses these variables under p->pi_lock and only does so after
2448 	 * smp_cond_load_acquire(&p->on_cpu, !VAL), and we're in __schedule()
2449 	 * before finish_task().
2450 	 *
2451 	 * XXX do further audits, this smells like something putrid.
2452 	 */
2453 	if (flags & SCA_MIGRATE_DISABLE)
2454 		SCHED_WARN_ON(!p->on_cpu);
2455 	else
2456 		lockdep_assert_held(&p->pi_lock);
2457 
2458 	queued = task_on_rq_queued(p);
2459 	running = task_current(rq, p);
2460 
2461 	if (queued) {
2462 		/*
2463 		 * Because __kthread_bind() calls this on blocked tasks without
2464 		 * holding rq->lock.
2465 		 */
2466 		lockdep_assert_rq_held(rq);
2467 		dequeue_task(rq, p, DEQUEUE_SAVE | DEQUEUE_NOCLOCK);
2468 	}
2469 	if (running)
2470 		put_prev_task(rq, p);
2471 
2472 	p->sched_class->set_cpus_allowed(p, new_mask, flags);
2473 
2474 	if (queued)
2475 		enqueue_task(rq, p, ENQUEUE_RESTORE | ENQUEUE_NOCLOCK);
2476 	if (running)
2477 		set_next_task(rq, p);
2478 }
2479 
2480 void do_set_cpus_allowed(struct task_struct *p, const struct cpumask *new_mask)
2481 {
2482 	__do_set_cpus_allowed(p, new_mask, 0);
2483 }
2484 
2485 /*
2486  * This function is wildly self concurrent; here be dragons.
2487  *
2488  *
2489  * When given a valid mask, __set_cpus_allowed_ptr() must block until the
2490  * designated task is enqueued on an allowed CPU. If that task is currently
2491  * running, we have to kick it out using the CPU stopper.
2492  *
2493  * Migrate-Disable comes along and tramples all over our nice sandcastle.
2494  * Consider:
2495  *
2496  *     Initial conditions: P0->cpus_mask = [0, 1]
2497  *
2498  *     P0@CPU0                  P1
2499  *
2500  *     migrate_disable();
2501  *     <preempted>
2502  *                              set_cpus_allowed_ptr(P0, [1]);
2503  *
2504  * P1 *cannot* return from this set_cpus_allowed_ptr() call until P0 executes
2505  * its outermost migrate_enable() (i.e. it exits its Migrate-Disable region).
2506  * This means we need the following scheme:
2507  *
2508  *     P0@CPU0                  P1
2509  *
2510  *     migrate_disable();
2511  *     <preempted>
2512  *                              set_cpus_allowed_ptr(P0, [1]);
2513  *                                <blocks>
2514  *     <resumes>
2515  *     migrate_enable();
2516  *       __set_cpus_allowed_ptr();
2517  *       <wakes local stopper>
2518  *                         `--> <woken on migration completion>
2519  *
2520  * Now the fun stuff: there may be several P1-like tasks, i.e. multiple
2521  * concurrent set_cpus_allowed_ptr(P0, [*]) calls. CPU affinity changes of any
2522  * task p are serialized by p->pi_lock, which we can leverage: the one that
2523  * should come into effect at the end of the Migrate-Disable region is the last
2524  * one. This means we only need to track a single cpumask (i.e. p->cpus_mask),
2525  * but we still need to properly signal those waiting tasks at the appropriate
2526  * moment.
2527  *
2528  * This is implemented using struct set_affinity_pending. The first
2529  * __set_cpus_allowed_ptr() caller within a given Migrate-Disable region will
2530  * setup an instance of that struct and install it on the targeted task_struct.
2531  * Any and all further callers will reuse that instance. Those then wait for
2532  * a completion signaled at the tail of the CPU stopper callback (1), triggered
2533  * on the end of the Migrate-Disable region (i.e. outermost migrate_enable()).
2534  *
2535  *
2536  * (1) In the cases covered above. There is one more where the completion is
2537  * signaled within affine_move_task() itself: when a subsequent affinity request
2538  * occurs after the stopper bailed out due to the targeted task still being
2539  * Migrate-Disable. Consider:
2540  *
2541  *     Initial conditions: P0->cpus_mask = [0, 1]
2542  *
2543  *     CPU0		  P1				P2
2544  *     <P0>
2545  *       migrate_disable();
2546  *       <preempted>
2547  *                        set_cpus_allowed_ptr(P0, [1]);
2548  *                          <blocks>
2549  *     <migration/0>
2550  *       migration_cpu_stop()
2551  *         is_migration_disabled()
2552  *           <bails>
2553  *                                                       set_cpus_allowed_ptr(P0, [0, 1]);
2554  *                                                         <signal completion>
2555  *                          <awakes>
2556  *
2557  * Note that the above is safe vs a concurrent migrate_enable(), as any
2558  * pending affinity completion is preceded by an uninstallation of
2559  * p->migration_pending done with p->pi_lock held.
2560  */
2561 static int affine_move_task(struct rq *rq, struct task_struct *p, struct rq_flags *rf,
2562 			    int dest_cpu, unsigned int flags)
2563 {
2564 	struct set_affinity_pending my_pending = { }, *pending = NULL;
2565 	bool stop_pending, complete = false;
2566 
2567 	/* Can the task run on the task's current CPU? If so, we're done */
2568 	if (cpumask_test_cpu(task_cpu(p), &p->cpus_mask)) {
2569 		struct task_struct *push_task = NULL;
2570 
2571 		if ((flags & SCA_MIGRATE_ENABLE) &&
2572 		    (p->migration_flags & MDF_PUSH) && !rq->push_busy) {
2573 			rq->push_busy = true;
2574 			push_task = get_task_struct(p);
2575 		}
2576 
2577 		/*
2578 		 * If there are pending waiters, but no pending stop_work,
2579 		 * then complete now.
2580 		 */
2581 		pending = p->migration_pending;
2582 		if (pending && !pending->stop_pending) {
2583 			p->migration_pending = NULL;
2584 			complete = true;
2585 		}
2586 
2587 		task_rq_unlock(rq, p, rf);
2588 
2589 		if (push_task) {
2590 			stop_one_cpu_nowait(rq->cpu, push_cpu_stop,
2591 					    p, &rq->push_work);
2592 		}
2593 
2594 		if (complete)
2595 			complete_all(&pending->done);
2596 
2597 		return 0;
2598 	}
2599 
2600 	if (!(flags & SCA_MIGRATE_ENABLE)) {
2601 		/* serialized by p->pi_lock */
2602 		if (!p->migration_pending) {
2603 			/* Install the request */
2604 			refcount_set(&my_pending.refs, 1);
2605 			init_completion(&my_pending.done);
2606 			my_pending.arg = (struct migration_arg) {
2607 				.task = p,
2608 				.dest_cpu = dest_cpu,
2609 				.pending = &my_pending,
2610 			};
2611 
2612 			p->migration_pending = &my_pending;
2613 		} else {
2614 			pending = p->migration_pending;
2615 			refcount_inc(&pending->refs);
2616 			/*
2617 			 * Affinity has changed, but we've already installed a
2618 			 * pending. migration_cpu_stop() *must* see this, else
2619 			 * we risk a completion of the pending despite having a
2620 			 * task on a disallowed CPU.
2621 			 *
2622 			 * Serialized by p->pi_lock, so this is safe.
2623 			 */
2624 			pending->arg.dest_cpu = dest_cpu;
2625 		}
2626 	}
2627 	pending = p->migration_pending;
2628 	/*
2629 	 * - !MIGRATE_ENABLE:
2630 	 *   we'll have installed a pending if there wasn't one already.
2631 	 *
2632 	 * - MIGRATE_ENABLE:
2633 	 *   we're here because the current CPU isn't matching anymore,
2634 	 *   the only way that can happen is because of a concurrent
2635 	 *   set_cpus_allowed_ptr() call, which should then still be
2636 	 *   pending completion.
2637 	 *
2638 	 * Either way, we really should have a @pending here.
2639 	 */
2640 	if (WARN_ON_ONCE(!pending)) {
2641 		task_rq_unlock(rq, p, rf);
2642 		return -EINVAL;
2643 	}
2644 
2645 	if (task_running(rq, p) || READ_ONCE(p->__state) == TASK_WAKING) {
2646 		/*
2647 		 * MIGRATE_ENABLE gets here because 'p == current', but for
2648 		 * anything else we cannot do is_migration_disabled(), punt
2649 		 * and have the stopper function handle it all race-free.
2650 		 */
2651 		stop_pending = pending->stop_pending;
2652 		if (!stop_pending)
2653 			pending->stop_pending = true;
2654 
2655 		if (flags & SCA_MIGRATE_ENABLE)
2656 			p->migration_flags &= ~MDF_PUSH;
2657 
2658 		task_rq_unlock(rq, p, rf);
2659 
2660 		if (!stop_pending) {
2661 			stop_one_cpu_nowait(cpu_of(rq), migration_cpu_stop,
2662 					    &pending->arg, &pending->stop_work);
2663 		}
2664 
2665 		if (flags & SCA_MIGRATE_ENABLE)
2666 			return 0;
2667 	} else {
2668 
2669 		if (!is_migration_disabled(p)) {
2670 			if (task_on_rq_queued(p))
2671 				rq = move_queued_task(rq, rf, p, dest_cpu);
2672 
2673 			if (!pending->stop_pending) {
2674 				p->migration_pending = NULL;
2675 				complete = true;
2676 			}
2677 		}
2678 		task_rq_unlock(rq, p, rf);
2679 
2680 		if (complete)
2681 			complete_all(&pending->done);
2682 	}
2683 
2684 	wait_for_completion(&pending->done);
2685 
2686 	if (refcount_dec_and_test(&pending->refs))
2687 		wake_up_var(&pending->refs); /* No UaF, just an address */
2688 
2689 	/*
2690 	 * Block the original owner of &pending until all subsequent callers
2691 	 * have seen the completion and decremented the refcount
2692 	 */
2693 	wait_var_event(&my_pending.refs, !refcount_read(&my_pending.refs));
2694 
2695 	/* ARGH */
2696 	WARN_ON_ONCE(my_pending.stop_pending);
2697 
2698 	return 0;
2699 }
2700 
2701 /*
2702  * Change a given task's CPU affinity. Migrate the thread to a
2703  * proper CPU and schedule it away if the CPU it's executing on
2704  * is removed from the allowed bitmask.
2705  *
2706  * NOTE: the caller must have a valid reference to the task, the
2707  * task must not exit() & deallocate itself prematurely. The
2708  * call is not atomic; no spinlocks may be held.
2709  */
2710 static int __set_cpus_allowed_ptr(struct task_struct *p,
2711 				  const struct cpumask *new_mask,
2712 				  u32 flags)
2713 {
2714 	const struct cpumask *cpu_valid_mask = cpu_active_mask;
2715 	unsigned int dest_cpu;
2716 	struct rq_flags rf;
2717 	struct rq *rq;
2718 	int ret = 0;
2719 
2720 	rq = task_rq_lock(p, &rf);
2721 	update_rq_clock(rq);
2722 
2723 	if (p->flags & PF_KTHREAD || is_migration_disabled(p)) {
2724 		/*
2725 		 * Kernel threads are allowed on online && !active CPUs,
2726 		 * however, during cpu-hot-unplug, even these might get pushed
2727 		 * away if not KTHREAD_IS_PER_CPU.
2728 		 *
2729 		 * Specifically, migration_disabled() tasks must not fail the
2730 		 * cpumask_any_and_distribute() pick below, esp. so on
2731 		 * SCA_MIGRATE_ENABLE, otherwise we'll not call
2732 		 * set_cpus_allowed_common() and actually reset p->cpus_ptr.
2733 		 */
2734 		cpu_valid_mask = cpu_online_mask;
2735 	}
2736 
2737 	/*
2738 	 * Must re-check here, to close a race against __kthread_bind(),
2739 	 * sched_setaffinity() is not guaranteed to observe the flag.
2740 	 */
2741 	if ((flags & SCA_CHECK) && (p->flags & PF_NO_SETAFFINITY)) {
2742 		ret = -EINVAL;
2743 		goto out;
2744 	}
2745 
2746 	if (!(flags & SCA_MIGRATE_ENABLE)) {
2747 		if (cpumask_equal(&p->cpus_mask, new_mask))
2748 			goto out;
2749 
2750 		if (WARN_ON_ONCE(p == current &&
2751 				 is_migration_disabled(p) &&
2752 				 !cpumask_test_cpu(task_cpu(p), new_mask))) {
2753 			ret = -EBUSY;
2754 			goto out;
2755 		}
2756 	}
2757 
2758 	/*
2759 	 * Picking a ~random cpu helps in cases where we are changing affinity
2760 	 * for groups of tasks (ie. cpuset), so that load balancing is not
2761 	 * immediately required to distribute the tasks within their new mask.
2762 	 */
2763 	dest_cpu = cpumask_any_and_distribute(cpu_valid_mask, new_mask);
2764 	if (dest_cpu >= nr_cpu_ids) {
2765 		ret = -EINVAL;
2766 		goto out;
2767 	}
2768 
2769 	__do_set_cpus_allowed(p, new_mask, flags);
2770 
2771 	return affine_move_task(rq, p, &rf, dest_cpu, flags);
2772 
2773 out:
2774 	task_rq_unlock(rq, p, &rf);
2775 
2776 	return ret;
2777 }
2778 
2779 int set_cpus_allowed_ptr(struct task_struct *p, const struct cpumask *new_mask)
2780 {
2781 	return __set_cpus_allowed_ptr(p, new_mask, 0);
2782 }
2783 EXPORT_SYMBOL_GPL(set_cpus_allowed_ptr);
2784 
2785 void set_task_cpu(struct task_struct *p, unsigned int new_cpu)
2786 {
2787 #ifdef CONFIG_SCHED_DEBUG
2788 	unsigned int state = READ_ONCE(p->__state);
2789 
2790 	/*
2791 	 * We should never call set_task_cpu() on a blocked task,
2792 	 * ttwu() will sort out the placement.
2793 	 */
2794 	WARN_ON_ONCE(state != TASK_RUNNING && state != TASK_WAKING && !p->on_rq);
2795 
2796 	/*
2797 	 * Migrating fair class task must have p->on_rq = TASK_ON_RQ_MIGRATING,
2798 	 * because schedstat_wait_{start,end} rebase migrating task's wait_start
2799 	 * time relying on p->on_rq.
2800 	 */
2801 	WARN_ON_ONCE(state == TASK_RUNNING &&
2802 		     p->sched_class == &fair_sched_class &&
2803 		     (p->on_rq && !task_on_rq_migrating(p)));
2804 
2805 #ifdef CONFIG_LOCKDEP
2806 	/*
2807 	 * The caller should hold either p->pi_lock or rq->lock, when changing
2808 	 * a task's CPU. ->pi_lock for waking tasks, rq->lock for runnable tasks.
2809 	 *
2810 	 * sched_move_task() holds both and thus holding either pins the cgroup,
2811 	 * see task_group().
2812 	 *
2813 	 * Furthermore, all task_rq users should acquire both locks, see
2814 	 * task_rq_lock().
2815 	 */
2816 	WARN_ON_ONCE(debug_locks && !(lockdep_is_held(&p->pi_lock) ||
2817 				      lockdep_is_held(__rq_lockp(task_rq(p)))));
2818 #endif
2819 	/*
2820 	 * Clearly, migrating tasks to offline CPUs is a fairly daft thing.
2821 	 */
2822 	WARN_ON_ONCE(!cpu_online(new_cpu));
2823 
2824 	WARN_ON_ONCE(is_migration_disabled(p));
2825 #endif
2826 
2827 	trace_sched_migrate_task(p, new_cpu);
2828 
2829 	if (task_cpu(p) != new_cpu) {
2830 		if (p->sched_class->migrate_task_rq)
2831 			p->sched_class->migrate_task_rq(p, new_cpu);
2832 		p->se.nr_migrations++;
2833 		rseq_migrate(p);
2834 		perf_event_task_migrate(p);
2835 	}
2836 
2837 	__set_task_cpu(p, new_cpu);
2838 }
2839 
2840 #ifdef CONFIG_NUMA_BALANCING
2841 static void __migrate_swap_task(struct task_struct *p, int cpu)
2842 {
2843 	if (task_on_rq_queued(p)) {
2844 		struct rq *src_rq, *dst_rq;
2845 		struct rq_flags srf, drf;
2846 
2847 		src_rq = task_rq(p);
2848 		dst_rq = cpu_rq(cpu);
2849 
2850 		rq_pin_lock(src_rq, &srf);
2851 		rq_pin_lock(dst_rq, &drf);
2852 
2853 		deactivate_task(src_rq, p, 0);
2854 		set_task_cpu(p, cpu);
2855 		activate_task(dst_rq, p, 0);
2856 		check_preempt_curr(dst_rq, p, 0);
2857 
2858 		rq_unpin_lock(dst_rq, &drf);
2859 		rq_unpin_lock(src_rq, &srf);
2860 
2861 	} else {
2862 		/*
2863 		 * Task isn't running anymore; make it appear like we migrated
2864 		 * it before it went to sleep. This means on wakeup we make the
2865 		 * previous CPU our target instead of where it really is.
2866 		 */
2867 		p->wake_cpu = cpu;
2868 	}
2869 }
2870 
2871 struct migration_swap_arg {
2872 	struct task_struct *src_task, *dst_task;
2873 	int src_cpu, dst_cpu;
2874 };
2875 
2876 static int migrate_swap_stop(void *data)
2877 {
2878 	struct migration_swap_arg *arg = data;
2879 	struct rq *src_rq, *dst_rq;
2880 	int ret = -EAGAIN;
2881 
2882 	if (!cpu_active(arg->src_cpu) || !cpu_active(arg->dst_cpu))
2883 		return -EAGAIN;
2884 
2885 	src_rq = cpu_rq(arg->src_cpu);
2886 	dst_rq = cpu_rq(arg->dst_cpu);
2887 
2888 	double_raw_lock(&arg->src_task->pi_lock,
2889 			&arg->dst_task->pi_lock);
2890 	double_rq_lock(src_rq, dst_rq);
2891 
2892 	if (task_cpu(arg->dst_task) != arg->dst_cpu)
2893 		goto unlock;
2894 
2895 	if (task_cpu(arg->src_task) != arg->src_cpu)
2896 		goto unlock;
2897 
2898 	if (!cpumask_test_cpu(arg->dst_cpu, arg->src_task->cpus_ptr))
2899 		goto unlock;
2900 
2901 	if (!cpumask_test_cpu(arg->src_cpu, arg->dst_task->cpus_ptr))
2902 		goto unlock;
2903 
2904 	__migrate_swap_task(arg->src_task, arg->dst_cpu);
2905 	__migrate_swap_task(arg->dst_task, arg->src_cpu);
2906 
2907 	ret = 0;
2908 
2909 unlock:
2910 	double_rq_unlock(src_rq, dst_rq);
2911 	raw_spin_unlock(&arg->dst_task->pi_lock);
2912 	raw_spin_unlock(&arg->src_task->pi_lock);
2913 
2914 	return ret;
2915 }
2916 
2917 /*
2918  * Cross migrate two tasks
2919  */
2920 int migrate_swap(struct task_struct *cur, struct task_struct *p,
2921 		int target_cpu, int curr_cpu)
2922 {
2923 	struct migration_swap_arg arg;
2924 	int ret = -EINVAL;
2925 
2926 	arg = (struct migration_swap_arg){
2927 		.src_task = cur,
2928 		.src_cpu = curr_cpu,
2929 		.dst_task = p,
2930 		.dst_cpu = target_cpu,
2931 	};
2932 
2933 	if (arg.src_cpu == arg.dst_cpu)
2934 		goto out;
2935 
2936 	/*
2937 	 * These three tests are all lockless; this is OK since all of them
2938 	 * will be re-checked with proper locks held further down the line.
2939 	 */
2940 	if (!cpu_active(arg.src_cpu) || !cpu_active(arg.dst_cpu))
2941 		goto out;
2942 
2943 	if (!cpumask_test_cpu(arg.dst_cpu, arg.src_task->cpus_ptr))
2944 		goto out;
2945 
2946 	if (!cpumask_test_cpu(arg.src_cpu, arg.dst_task->cpus_ptr))
2947 		goto out;
2948 
2949 	trace_sched_swap_numa(cur, arg.src_cpu, p, arg.dst_cpu);
2950 	ret = stop_two_cpus(arg.dst_cpu, arg.src_cpu, migrate_swap_stop, &arg);
2951 
2952 out:
2953 	return ret;
2954 }
2955 #endif /* CONFIG_NUMA_BALANCING */
2956 
2957 /*
2958  * wait_task_inactive - wait for a thread to unschedule.
2959  *
2960  * If @match_state is nonzero, it's the @p->state value just checked and
2961  * not expected to change.  If it changes, i.e. @p might have woken up,
2962  * then return zero.  When we succeed in waiting for @p to be off its CPU,
2963  * we return a positive number (its total switch count).  If a second call
2964  * a short while later returns the same number, the caller can be sure that
2965  * @p has remained unscheduled the whole time.
2966  *
2967  * The caller must ensure that the task *will* unschedule sometime soon,
2968  * else this function might spin for a *long* time. This function can't
2969  * be called with interrupts off, or it may introduce deadlock with
2970  * smp_call_function() if an IPI is sent by the same process we are
2971  * waiting to become inactive.
2972  */
2973 unsigned long wait_task_inactive(struct task_struct *p, unsigned int match_state)
2974 {
2975 	int running, queued;
2976 	struct rq_flags rf;
2977 	unsigned long ncsw;
2978 	struct rq *rq;
2979 
2980 	for (;;) {
2981 		/*
2982 		 * We do the initial early heuristics without holding
2983 		 * any task-queue locks at all. We'll only try to get
2984 		 * the runqueue lock when things look like they will
2985 		 * work out!
2986 		 */
2987 		rq = task_rq(p);
2988 
2989 		/*
2990 		 * If the task is actively running on another CPU
2991 		 * still, just relax and busy-wait without holding
2992 		 * any locks.
2993 		 *
2994 		 * NOTE! Since we don't hold any locks, it's not
2995 		 * even sure that "rq" stays as the right runqueue!
2996 		 * But we don't care, since "task_running()" will
2997 		 * return false if the runqueue has changed and p
2998 		 * is actually now running somewhere else!
2999 		 */
3000 		while (task_running(rq, p)) {
3001 			if (match_state && unlikely(READ_ONCE(p->__state) != match_state))
3002 				return 0;
3003 			cpu_relax();
3004 		}
3005 
3006 		/*
3007 		 * Ok, time to look more closely! We need the rq
3008 		 * lock now, to be *sure*. If we're wrong, we'll
3009 		 * just go back and repeat.
3010 		 */
3011 		rq = task_rq_lock(p, &rf);
3012 		trace_sched_wait_task(p);
3013 		running = task_running(rq, p);
3014 		queued = task_on_rq_queued(p);
3015 		ncsw = 0;
3016 		if (!match_state || READ_ONCE(p->__state) == match_state)
3017 			ncsw = p->nvcsw | LONG_MIN; /* sets MSB */
3018 		task_rq_unlock(rq, p, &rf);
3019 
3020 		/*
3021 		 * If it changed from the expected state, bail out now.
3022 		 */
3023 		if (unlikely(!ncsw))
3024 			break;
3025 
3026 		/*
3027 		 * Was it really running after all now that we
3028 		 * checked with the proper locks actually held?
3029 		 *
3030 		 * Oops. Go back and try again..
3031 		 */
3032 		if (unlikely(running)) {
3033 			cpu_relax();
3034 			continue;
3035 		}
3036 
3037 		/*
3038 		 * It's not enough that it's not actively running,
3039 		 * it must be off the runqueue _entirely_, and not
3040 		 * preempted!
3041 		 *
3042 		 * So if it was still runnable (but just not actively
3043 		 * running right now), it's preempted, and we should
3044 		 * yield - it could be a while.
3045 		 */
3046 		if (unlikely(queued)) {
3047 			ktime_t to = NSEC_PER_SEC / HZ;
3048 
3049 			set_current_state(TASK_UNINTERRUPTIBLE);
3050 			schedule_hrtimeout(&to, HRTIMER_MODE_REL);
3051 			continue;
3052 		}
3053 
3054 		/*
3055 		 * Ahh, all good. It wasn't running, and it wasn't
3056 		 * runnable, which means that it will never become
3057 		 * running in the future either. We're all done!
3058 		 */
3059 		break;
3060 	}
3061 
3062 	return ncsw;
3063 }
3064 
3065 /***
3066  * kick_process - kick a running thread to enter/exit the kernel
3067  * @p: the to-be-kicked thread
3068  *
3069  * Cause a process which is running on another CPU to enter
3070  * kernel-mode, without any delay. (to get signals handled.)
3071  *
3072  * NOTE: this function doesn't have to take the runqueue lock,
3073  * because all it wants to ensure is that the remote task enters
3074  * the kernel. If the IPI races and the task has been migrated
3075  * to another CPU then no harm is done and the purpose has been
3076  * achieved as well.
3077  */
3078 void kick_process(struct task_struct *p)
3079 {
3080 	int cpu;
3081 
3082 	preempt_disable();
3083 	cpu = task_cpu(p);
3084 	if ((cpu != smp_processor_id()) && task_curr(p))
3085 		smp_send_reschedule(cpu);
3086 	preempt_enable();
3087 }
3088 EXPORT_SYMBOL_GPL(kick_process);
3089 
3090 /*
3091  * ->cpus_ptr is protected by both rq->lock and p->pi_lock
3092  *
3093  * A few notes on cpu_active vs cpu_online:
3094  *
3095  *  - cpu_active must be a subset of cpu_online
3096  *
3097  *  - on CPU-up we allow per-CPU kthreads on the online && !active CPU,
3098  *    see __set_cpus_allowed_ptr(). At this point the newly online
3099  *    CPU isn't yet part of the sched domains, and balancing will not
3100  *    see it.
3101  *
3102  *  - on CPU-down we clear cpu_active() to mask the sched domains and
3103  *    avoid the load balancer to place new tasks on the to be removed
3104  *    CPU. Existing tasks will remain running there and will be taken
3105  *    off.
3106  *
3107  * This means that fallback selection must not select !active CPUs.
3108  * And can assume that any active CPU must be online. Conversely
3109  * select_task_rq() below may allow selection of !active CPUs in order
3110  * to satisfy the above rules.
3111  */
3112 static int select_fallback_rq(int cpu, struct task_struct *p)
3113 {
3114 	int nid = cpu_to_node(cpu);
3115 	const struct cpumask *nodemask = NULL;
3116 	enum { cpuset, possible, fail } state = cpuset;
3117 	int dest_cpu;
3118 
3119 	/*
3120 	 * If the node that the CPU is on has been offlined, cpu_to_node()
3121 	 * will return -1. There is no CPU on the node, and we should
3122 	 * select the CPU on the other node.
3123 	 */
3124 	if (nid != -1) {
3125 		nodemask = cpumask_of_node(nid);
3126 
3127 		/* Look for allowed, online CPU in same node. */
3128 		for_each_cpu(dest_cpu, nodemask) {
3129 			if (!cpu_active(dest_cpu))
3130 				continue;
3131 			if (cpumask_test_cpu(dest_cpu, p->cpus_ptr))
3132 				return dest_cpu;
3133 		}
3134 	}
3135 
3136 	for (;;) {
3137 		/* Any allowed, online CPU? */
3138 		for_each_cpu(dest_cpu, p->cpus_ptr) {
3139 			if (!is_cpu_allowed(p, dest_cpu))
3140 				continue;
3141 
3142 			goto out;
3143 		}
3144 
3145 		/* No more Mr. Nice Guy. */
3146 		switch (state) {
3147 		case cpuset:
3148 			if (IS_ENABLED(CONFIG_CPUSETS)) {
3149 				cpuset_cpus_allowed_fallback(p);
3150 				state = possible;
3151 				break;
3152 			}
3153 			fallthrough;
3154 		case possible:
3155 			/*
3156 			 * XXX When called from select_task_rq() we only
3157 			 * hold p->pi_lock and again violate locking order.
3158 			 *
3159 			 * More yuck to audit.
3160 			 */
3161 			do_set_cpus_allowed(p, cpu_possible_mask);
3162 			state = fail;
3163 			break;
3164 
3165 		case fail:
3166 			BUG();
3167 			break;
3168 		}
3169 	}
3170 
3171 out:
3172 	if (state != cpuset) {
3173 		/*
3174 		 * Don't tell them about moving exiting tasks or
3175 		 * kernel threads (both mm NULL), since they never
3176 		 * leave kernel.
3177 		 */
3178 		if (p->mm && printk_ratelimit()) {
3179 			printk_deferred("process %d (%s) no longer affine to cpu%d\n",
3180 					task_pid_nr(p), p->comm, cpu);
3181 		}
3182 	}
3183 
3184 	return dest_cpu;
3185 }
3186 
3187 /*
3188  * The caller (fork, wakeup) owns p->pi_lock, ->cpus_ptr is stable.
3189  */
3190 static inline
3191 int select_task_rq(struct task_struct *p, int cpu, int wake_flags)
3192 {
3193 	lockdep_assert_held(&p->pi_lock);
3194 
3195 	if (p->nr_cpus_allowed > 1 && !is_migration_disabled(p))
3196 		cpu = p->sched_class->select_task_rq(p, cpu, wake_flags);
3197 	else
3198 		cpu = cpumask_any(p->cpus_ptr);
3199 
3200 	/*
3201 	 * In order not to call set_task_cpu() on a blocking task we need
3202 	 * to rely on ttwu() to place the task on a valid ->cpus_ptr
3203 	 * CPU.
3204 	 *
3205 	 * Since this is common to all placement strategies, this lives here.
3206 	 *
3207 	 * [ this allows ->select_task() to simply return task_cpu(p) and
3208 	 *   not worry about this generic constraint ]
3209 	 */
3210 	if (unlikely(!is_cpu_allowed(p, cpu)))
3211 		cpu = select_fallback_rq(task_cpu(p), p);
3212 
3213 	return cpu;
3214 }
3215 
3216 void sched_set_stop_task(int cpu, struct task_struct *stop)
3217 {
3218 	static struct lock_class_key stop_pi_lock;
3219 	struct sched_param param = { .sched_priority = MAX_RT_PRIO - 1 };
3220 	struct task_struct *old_stop = cpu_rq(cpu)->stop;
3221 
3222 	if (stop) {
3223 		/*
3224 		 * Make it appear like a SCHED_FIFO task, its something
3225 		 * userspace knows about and won't get confused about.
3226 		 *
3227 		 * Also, it will make PI more or less work without too
3228 		 * much confusion -- but then, stop work should not
3229 		 * rely on PI working anyway.
3230 		 */
3231 		sched_setscheduler_nocheck(stop, SCHED_FIFO, &param);
3232 
3233 		stop->sched_class = &stop_sched_class;
3234 
3235 		/*
3236 		 * The PI code calls rt_mutex_setprio() with ->pi_lock held to
3237 		 * adjust the effective priority of a task. As a result,
3238 		 * rt_mutex_setprio() can trigger (RT) balancing operations,
3239 		 * which can then trigger wakeups of the stop thread to push
3240 		 * around the current task.
3241 		 *
3242 		 * The stop task itself will never be part of the PI-chain, it
3243 		 * never blocks, therefore that ->pi_lock recursion is safe.
3244 		 * Tell lockdep about this by placing the stop->pi_lock in its
3245 		 * own class.
3246 		 */
3247 		lockdep_set_class(&stop->pi_lock, &stop_pi_lock);
3248 	}
3249 
3250 	cpu_rq(cpu)->stop = stop;
3251 
3252 	if (old_stop) {
3253 		/*
3254 		 * Reset it back to a normal scheduling class so that
3255 		 * it can die in pieces.
3256 		 */
3257 		old_stop->sched_class = &rt_sched_class;
3258 	}
3259 }
3260 
3261 #else /* CONFIG_SMP */
3262 
3263 static inline int __set_cpus_allowed_ptr(struct task_struct *p,
3264 					 const struct cpumask *new_mask,
3265 					 u32 flags)
3266 {
3267 	return set_cpus_allowed_ptr(p, new_mask);
3268 }
3269 
3270 static inline void migrate_disable_switch(struct rq *rq, struct task_struct *p) { }
3271 
3272 static inline bool rq_has_pinned_tasks(struct rq *rq)
3273 {
3274 	return false;
3275 }
3276 
3277 #endif /* !CONFIG_SMP */
3278 
3279 static void
3280 ttwu_stat(struct task_struct *p, int cpu, int wake_flags)
3281 {
3282 	struct rq *rq;
3283 
3284 	if (!schedstat_enabled())
3285 		return;
3286 
3287 	rq = this_rq();
3288 
3289 #ifdef CONFIG_SMP
3290 	if (cpu == rq->cpu) {
3291 		__schedstat_inc(rq->ttwu_local);
3292 		__schedstat_inc(p->se.statistics.nr_wakeups_local);
3293 	} else {
3294 		struct sched_domain *sd;
3295 
3296 		__schedstat_inc(p->se.statistics.nr_wakeups_remote);
3297 		rcu_read_lock();
3298 		for_each_domain(rq->cpu, sd) {
3299 			if (cpumask_test_cpu(cpu, sched_domain_span(sd))) {
3300 				__schedstat_inc(sd->ttwu_wake_remote);
3301 				break;
3302 			}
3303 		}
3304 		rcu_read_unlock();
3305 	}
3306 
3307 	if (wake_flags & WF_MIGRATED)
3308 		__schedstat_inc(p->se.statistics.nr_wakeups_migrate);
3309 #endif /* CONFIG_SMP */
3310 
3311 	__schedstat_inc(rq->ttwu_count);
3312 	__schedstat_inc(p->se.statistics.nr_wakeups);
3313 
3314 	if (wake_flags & WF_SYNC)
3315 		__schedstat_inc(p->se.statistics.nr_wakeups_sync);
3316 }
3317 
3318 /*
3319  * Mark the task runnable and perform wakeup-preemption.
3320  */
3321 static void ttwu_do_wakeup(struct rq *rq, struct task_struct *p, int wake_flags,
3322 			   struct rq_flags *rf)
3323 {
3324 	check_preempt_curr(rq, p, wake_flags);
3325 	WRITE_ONCE(p->__state, TASK_RUNNING);
3326 	trace_sched_wakeup(p);
3327 
3328 #ifdef CONFIG_SMP
3329 	if (p->sched_class->task_woken) {
3330 		/*
3331 		 * Our task @p is fully woken up and running; so it's safe to
3332 		 * drop the rq->lock, hereafter rq is only used for statistics.
3333 		 */
3334 		rq_unpin_lock(rq, rf);
3335 		p->sched_class->task_woken(rq, p);
3336 		rq_repin_lock(rq, rf);
3337 	}
3338 
3339 	if (rq->idle_stamp) {
3340 		u64 delta = rq_clock(rq) - rq->idle_stamp;
3341 		u64 max = 2*rq->max_idle_balance_cost;
3342 
3343 		update_avg(&rq->avg_idle, delta);
3344 
3345 		if (rq->avg_idle > max)
3346 			rq->avg_idle = max;
3347 
3348 		rq->wake_stamp = jiffies;
3349 		rq->wake_avg_idle = rq->avg_idle / 2;
3350 
3351 		rq->idle_stamp = 0;
3352 	}
3353 #endif
3354 }
3355 
3356 static void
3357 ttwu_do_activate(struct rq *rq, struct task_struct *p, int wake_flags,
3358 		 struct rq_flags *rf)
3359 {
3360 	int en_flags = ENQUEUE_WAKEUP | ENQUEUE_NOCLOCK;
3361 
3362 	lockdep_assert_rq_held(rq);
3363 
3364 	if (p->sched_contributes_to_load)
3365 		rq->nr_uninterruptible--;
3366 
3367 #ifdef CONFIG_SMP
3368 	if (wake_flags & WF_MIGRATED)
3369 		en_flags |= ENQUEUE_MIGRATED;
3370 	else
3371 #endif
3372 	if (p->in_iowait) {
3373 		delayacct_blkio_end(p);
3374 		atomic_dec(&task_rq(p)->nr_iowait);
3375 	}
3376 
3377 	activate_task(rq, p, en_flags);
3378 	ttwu_do_wakeup(rq, p, wake_flags, rf);
3379 }
3380 
3381 /*
3382  * Consider @p being inside a wait loop:
3383  *
3384  *   for (;;) {
3385  *      set_current_state(TASK_UNINTERRUPTIBLE);
3386  *
3387  *      if (CONDITION)
3388  *         break;
3389  *
3390  *      schedule();
3391  *   }
3392  *   __set_current_state(TASK_RUNNING);
3393  *
3394  * between set_current_state() and schedule(). In this case @p is still
3395  * runnable, so all that needs doing is change p->state back to TASK_RUNNING in
3396  * an atomic manner.
3397  *
3398  * By taking task_rq(p)->lock we serialize against schedule(), if @p->on_rq
3399  * then schedule() must still happen and p->state can be changed to
3400  * TASK_RUNNING. Otherwise we lost the race, schedule() has happened, and we
3401  * need to do a full wakeup with enqueue.
3402  *
3403  * Returns: %true when the wakeup is done,
3404  *          %false otherwise.
3405  */
3406 static int ttwu_runnable(struct task_struct *p, int wake_flags)
3407 {
3408 	struct rq_flags rf;
3409 	struct rq *rq;
3410 	int ret = 0;
3411 
3412 	rq = __task_rq_lock(p, &rf);
3413 	if (task_on_rq_queued(p)) {
3414 		/* check_preempt_curr() may use rq clock */
3415 		update_rq_clock(rq);
3416 		ttwu_do_wakeup(rq, p, wake_flags, &rf);
3417 		ret = 1;
3418 	}
3419 	__task_rq_unlock(rq, &rf);
3420 
3421 	return ret;
3422 }
3423 
3424 #ifdef CONFIG_SMP
3425 void sched_ttwu_pending(void *arg)
3426 {
3427 	struct llist_node *llist = arg;
3428 	struct rq *rq = this_rq();
3429 	struct task_struct *p, *t;
3430 	struct rq_flags rf;
3431 
3432 	if (!llist)
3433 		return;
3434 
3435 	/*
3436 	 * rq::ttwu_pending racy indication of out-standing wakeups.
3437 	 * Races such that false-negatives are possible, since they
3438 	 * are shorter lived that false-positives would be.
3439 	 */
3440 	WRITE_ONCE(rq->ttwu_pending, 0);
3441 
3442 	rq_lock_irqsave(rq, &rf);
3443 	update_rq_clock(rq);
3444 
3445 	llist_for_each_entry_safe(p, t, llist, wake_entry.llist) {
3446 		if (WARN_ON_ONCE(p->on_cpu))
3447 			smp_cond_load_acquire(&p->on_cpu, !VAL);
3448 
3449 		if (WARN_ON_ONCE(task_cpu(p) != cpu_of(rq)))
3450 			set_task_cpu(p, cpu_of(rq));
3451 
3452 		ttwu_do_activate(rq, p, p->sched_remote_wakeup ? WF_MIGRATED : 0, &rf);
3453 	}
3454 
3455 	rq_unlock_irqrestore(rq, &rf);
3456 }
3457 
3458 void send_call_function_single_ipi(int cpu)
3459 {
3460 	struct rq *rq = cpu_rq(cpu);
3461 
3462 	if (!set_nr_if_polling(rq->idle))
3463 		arch_send_call_function_single_ipi(cpu);
3464 	else
3465 		trace_sched_wake_idle_without_ipi(cpu);
3466 }
3467 
3468 /*
3469  * Queue a task on the target CPUs wake_list and wake the CPU via IPI if
3470  * necessary. The wakee CPU on receipt of the IPI will queue the task
3471  * via sched_ttwu_wakeup() for activation so the wakee incurs the cost
3472  * of the wakeup instead of the waker.
3473  */
3474 static void __ttwu_queue_wakelist(struct task_struct *p, int cpu, int wake_flags)
3475 {
3476 	struct rq *rq = cpu_rq(cpu);
3477 
3478 	p->sched_remote_wakeup = !!(wake_flags & WF_MIGRATED);
3479 
3480 	WRITE_ONCE(rq->ttwu_pending, 1);
3481 	__smp_call_single_queue(cpu, &p->wake_entry.llist);
3482 }
3483 
3484 void wake_up_if_idle(int cpu)
3485 {
3486 	struct rq *rq = cpu_rq(cpu);
3487 	struct rq_flags rf;
3488 
3489 	rcu_read_lock();
3490 
3491 	if (!is_idle_task(rcu_dereference(rq->curr)))
3492 		goto out;
3493 
3494 	if (set_nr_if_polling(rq->idle)) {
3495 		trace_sched_wake_idle_without_ipi(cpu);
3496 	} else {
3497 		rq_lock_irqsave(rq, &rf);
3498 		if (is_idle_task(rq->curr))
3499 			smp_send_reschedule(cpu);
3500 		/* Else CPU is not idle, do nothing here: */
3501 		rq_unlock_irqrestore(rq, &rf);
3502 	}
3503 
3504 out:
3505 	rcu_read_unlock();
3506 }
3507 
3508 bool cpus_share_cache(int this_cpu, int that_cpu)
3509 {
3510 	return per_cpu(sd_llc_id, this_cpu) == per_cpu(sd_llc_id, that_cpu);
3511 }
3512 
3513 static inline bool ttwu_queue_cond(int cpu, int wake_flags)
3514 {
3515 	/*
3516 	 * Do not complicate things with the async wake_list while the CPU is
3517 	 * in hotplug state.
3518 	 */
3519 	if (!cpu_active(cpu))
3520 		return false;
3521 
3522 	/*
3523 	 * If the CPU does not share cache, then queue the task on the
3524 	 * remote rqs wakelist to avoid accessing remote data.
3525 	 */
3526 	if (!cpus_share_cache(smp_processor_id(), cpu))
3527 		return true;
3528 
3529 	/*
3530 	 * If the task is descheduling and the only running task on the
3531 	 * CPU then use the wakelist to offload the task activation to
3532 	 * the soon-to-be-idle CPU as the current CPU is likely busy.
3533 	 * nr_running is checked to avoid unnecessary task stacking.
3534 	 */
3535 	if ((wake_flags & WF_ON_CPU) && cpu_rq(cpu)->nr_running <= 1)
3536 		return true;
3537 
3538 	return false;
3539 }
3540 
3541 static bool ttwu_queue_wakelist(struct task_struct *p, int cpu, int wake_flags)
3542 {
3543 	if (sched_feat(TTWU_QUEUE) && ttwu_queue_cond(cpu, wake_flags)) {
3544 		if (WARN_ON_ONCE(cpu == smp_processor_id()))
3545 			return false;
3546 
3547 		sched_clock_cpu(cpu); /* Sync clocks across CPUs */
3548 		__ttwu_queue_wakelist(p, cpu, wake_flags);
3549 		return true;
3550 	}
3551 
3552 	return false;
3553 }
3554 
3555 #else /* !CONFIG_SMP */
3556 
3557 static inline bool ttwu_queue_wakelist(struct task_struct *p, int cpu, int wake_flags)
3558 {
3559 	return false;
3560 }
3561 
3562 #endif /* CONFIG_SMP */
3563 
3564 static void ttwu_queue(struct task_struct *p, int cpu, int wake_flags)
3565 {
3566 	struct rq *rq = cpu_rq(cpu);
3567 	struct rq_flags rf;
3568 
3569 	if (ttwu_queue_wakelist(p, cpu, wake_flags))
3570 		return;
3571 
3572 	rq_lock(rq, &rf);
3573 	update_rq_clock(rq);
3574 	ttwu_do_activate(rq, p, wake_flags, &rf);
3575 	rq_unlock(rq, &rf);
3576 }
3577 
3578 /*
3579  * Notes on Program-Order guarantees on SMP systems.
3580  *
3581  *  MIGRATION
3582  *
3583  * The basic program-order guarantee on SMP systems is that when a task [t]
3584  * migrates, all its activity on its old CPU [c0] happens-before any subsequent
3585  * execution on its new CPU [c1].
3586  *
3587  * For migration (of runnable tasks) this is provided by the following means:
3588  *
3589  *  A) UNLOCK of the rq(c0)->lock scheduling out task t
3590  *  B) migration for t is required to synchronize *both* rq(c0)->lock and
3591  *     rq(c1)->lock (if not at the same time, then in that order).
3592  *  C) LOCK of the rq(c1)->lock scheduling in task
3593  *
3594  * Release/acquire chaining guarantees that B happens after A and C after B.
3595  * Note: the CPU doing B need not be c0 or c1
3596  *
3597  * Example:
3598  *
3599  *   CPU0            CPU1            CPU2
3600  *
3601  *   LOCK rq(0)->lock
3602  *   sched-out X
3603  *   sched-in Y
3604  *   UNLOCK rq(0)->lock
3605  *
3606  *                                   LOCK rq(0)->lock // orders against CPU0
3607  *                                   dequeue X
3608  *                                   UNLOCK rq(0)->lock
3609  *
3610  *                                   LOCK rq(1)->lock
3611  *                                   enqueue X
3612  *                                   UNLOCK rq(1)->lock
3613  *
3614  *                   LOCK rq(1)->lock // orders against CPU2
3615  *                   sched-out Z
3616  *                   sched-in X
3617  *                   UNLOCK rq(1)->lock
3618  *
3619  *
3620  *  BLOCKING -- aka. SLEEP + WAKEUP
3621  *
3622  * For blocking we (obviously) need to provide the same guarantee as for
3623  * migration. However the means are completely different as there is no lock
3624  * chain to provide order. Instead we do:
3625  *
3626  *   1) smp_store_release(X->on_cpu, 0)   -- finish_task()
3627  *   2) smp_cond_load_acquire(!X->on_cpu) -- try_to_wake_up()
3628  *
3629  * Example:
3630  *
3631  *   CPU0 (schedule)  CPU1 (try_to_wake_up) CPU2 (schedule)
3632  *
3633  *   LOCK rq(0)->lock LOCK X->pi_lock
3634  *   dequeue X
3635  *   sched-out X
3636  *   smp_store_release(X->on_cpu, 0);
3637  *
3638  *                    smp_cond_load_acquire(&X->on_cpu, !VAL);
3639  *                    X->state = WAKING
3640  *                    set_task_cpu(X,2)
3641  *
3642  *                    LOCK rq(2)->lock
3643  *                    enqueue X
3644  *                    X->state = RUNNING
3645  *                    UNLOCK rq(2)->lock
3646  *
3647  *                                          LOCK rq(2)->lock // orders against CPU1
3648  *                                          sched-out Z
3649  *                                          sched-in X
3650  *                                          UNLOCK rq(2)->lock
3651  *
3652  *                    UNLOCK X->pi_lock
3653  *   UNLOCK rq(0)->lock
3654  *
3655  *
3656  * However, for wakeups there is a second guarantee we must provide, namely we
3657  * must ensure that CONDITION=1 done by the caller can not be reordered with
3658  * accesses to the task state; see try_to_wake_up() and set_current_state().
3659  */
3660 
3661 /**
3662  * try_to_wake_up - wake up a thread
3663  * @p: the thread to be awakened
3664  * @state: the mask of task states that can be woken
3665  * @wake_flags: wake modifier flags (WF_*)
3666  *
3667  * Conceptually does:
3668  *
3669  *   If (@state & @p->state) @p->state = TASK_RUNNING.
3670  *
3671  * If the task was not queued/runnable, also place it back on a runqueue.
3672  *
3673  * This function is atomic against schedule() which would dequeue the task.
3674  *
3675  * It issues a full memory barrier before accessing @p->state, see the comment
3676  * with set_current_state().
3677  *
3678  * Uses p->pi_lock to serialize against concurrent wake-ups.
3679  *
3680  * Relies on p->pi_lock stabilizing:
3681  *  - p->sched_class
3682  *  - p->cpus_ptr
3683  *  - p->sched_task_group
3684  * in order to do migration, see its use of select_task_rq()/set_task_cpu().
3685  *
3686  * Tries really hard to only take one task_rq(p)->lock for performance.
3687  * Takes rq->lock in:
3688  *  - ttwu_runnable()    -- old rq, unavoidable, see comment there;
3689  *  - ttwu_queue()       -- new rq, for enqueue of the task;
3690  *  - psi_ttwu_dequeue() -- much sadness :-( accounting will kill us.
3691  *
3692  * As a consequence we race really badly with just about everything. See the
3693  * many memory barriers and their comments for details.
3694  *
3695  * Return: %true if @p->state changes (an actual wakeup was done),
3696  *	   %false otherwise.
3697  */
3698 static int
3699 try_to_wake_up(struct task_struct *p, unsigned int state, int wake_flags)
3700 {
3701 	unsigned long flags;
3702 	int cpu, success = 0;
3703 
3704 	preempt_disable();
3705 	if (p == current) {
3706 		/*
3707 		 * We're waking current, this means 'p->on_rq' and 'task_cpu(p)
3708 		 * == smp_processor_id()'. Together this means we can special
3709 		 * case the whole 'p->on_rq && ttwu_runnable()' case below
3710 		 * without taking any locks.
3711 		 *
3712 		 * In particular:
3713 		 *  - we rely on Program-Order guarantees for all the ordering,
3714 		 *  - we're serialized against set_special_state() by virtue of
3715 		 *    it disabling IRQs (this allows not taking ->pi_lock).
3716 		 */
3717 		if (!(READ_ONCE(p->__state) & state))
3718 			goto out;
3719 
3720 		success = 1;
3721 		trace_sched_waking(p);
3722 		WRITE_ONCE(p->__state, TASK_RUNNING);
3723 		trace_sched_wakeup(p);
3724 		goto out;
3725 	}
3726 
3727 	/*
3728 	 * If we are going to wake up a thread waiting for CONDITION we
3729 	 * need to ensure that CONDITION=1 done by the caller can not be
3730 	 * reordered with p->state check below. This pairs with smp_store_mb()
3731 	 * in set_current_state() that the waiting thread does.
3732 	 */
3733 	raw_spin_lock_irqsave(&p->pi_lock, flags);
3734 	smp_mb__after_spinlock();
3735 	if (!(READ_ONCE(p->__state) & state))
3736 		goto unlock;
3737 
3738 	trace_sched_waking(p);
3739 
3740 	/* We're going to change ->state: */
3741 	success = 1;
3742 
3743 	/*
3744 	 * Ensure we load p->on_rq _after_ p->state, otherwise it would
3745 	 * be possible to, falsely, observe p->on_rq == 0 and get stuck
3746 	 * in smp_cond_load_acquire() below.
3747 	 *
3748 	 * sched_ttwu_pending()			try_to_wake_up()
3749 	 *   STORE p->on_rq = 1			  LOAD p->state
3750 	 *   UNLOCK rq->lock
3751 	 *
3752 	 * __schedule() (switch to task 'p')
3753 	 *   LOCK rq->lock			  smp_rmb();
3754 	 *   smp_mb__after_spinlock();
3755 	 *   UNLOCK rq->lock
3756 	 *
3757 	 * [task p]
3758 	 *   STORE p->state = UNINTERRUPTIBLE	  LOAD p->on_rq
3759 	 *
3760 	 * Pairs with the LOCK+smp_mb__after_spinlock() on rq->lock in
3761 	 * __schedule().  See the comment for smp_mb__after_spinlock().
3762 	 *
3763 	 * A similar smb_rmb() lives in try_invoke_on_locked_down_task().
3764 	 */
3765 	smp_rmb();
3766 	if (READ_ONCE(p->on_rq) && ttwu_runnable(p, wake_flags))
3767 		goto unlock;
3768 
3769 #ifdef CONFIG_SMP
3770 	/*
3771 	 * Ensure we load p->on_cpu _after_ p->on_rq, otherwise it would be
3772 	 * possible to, falsely, observe p->on_cpu == 0.
3773 	 *
3774 	 * One must be running (->on_cpu == 1) in order to remove oneself
3775 	 * from the runqueue.
3776 	 *
3777 	 * __schedule() (switch to task 'p')	try_to_wake_up()
3778 	 *   STORE p->on_cpu = 1		  LOAD p->on_rq
3779 	 *   UNLOCK rq->lock
3780 	 *
3781 	 * __schedule() (put 'p' to sleep)
3782 	 *   LOCK rq->lock			  smp_rmb();
3783 	 *   smp_mb__after_spinlock();
3784 	 *   STORE p->on_rq = 0			  LOAD p->on_cpu
3785 	 *
3786 	 * Pairs with the LOCK+smp_mb__after_spinlock() on rq->lock in
3787 	 * __schedule().  See the comment for smp_mb__after_spinlock().
3788 	 *
3789 	 * Form a control-dep-acquire with p->on_rq == 0 above, to ensure
3790 	 * schedule()'s deactivate_task() has 'happened' and p will no longer
3791 	 * care about it's own p->state. See the comment in __schedule().
3792 	 */
3793 	smp_acquire__after_ctrl_dep();
3794 
3795 	/*
3796 	 * We're doing the wakeup (@success == 1), they did a dequeue (p->on_rq
3797 	 * == 0), which means we need to do an enqueue, change p->state to
3798 	 * TASK_WAKING such that we can unlock p->pi_lock before doing the
3799 	 * enqueue, such as ttwu_queue_wakelist().
3800 	 */
3801 	WRITE_ONCE(p->__state, TASK_WAKING);
3802 
3803 	/*
3804 	 * If the owning (remote) CPU is still in the middle of schedule() with
3805 	 * this task as prev, considering queueing p on the remote CPUs wake_list
3806 	 * which potentially sends an IPI instead of spinning on p->on_cpu to
3807 	 * let the waker make forward progress. This is safe because IRQs are
3808 	 * disabled and the IPI will deliver after on_cpu is cleared.
3809 	 *
3810 	 * Ensure we load task_cpu(p) after p->on_cpu:
3811 	 *
3812 	 * set_task_cpu(p, cpu);
3813 	 *   STORE p->cpu = @cpu
3814 	 * __schedule() (switch to task 'p')
3815 	 *   LOCK rq->lock
3816 	 *   smp_mb__after_spin_lock()		smp_cond_load_acquire(&p->on_cpu)
3817 	 *   STORE p->on_cpu = 1		LOAD p->cpu
3818 	 *
3819 	 * to ensure we observe the correct CPU on which the task is currently
3820 	 * scheduling.
3821 	 */
3822 	if (smp_load_acquire(&p->on_cpu) &&
3823 	    ttwu_queue_wakelist(p, task_cpu(p), wake_flags | WF_ON_CPU))
3824 		goto unlock;
3825 
3826 	/*
3827 	 * If the owning (remote) CPU is still in the middle of schedule() with
3828 	 * this task as prev, wait until it's done referencing the task.
3829 	 *
3830 	 * Pairs with the smp_store_release() in finish_task().
3831 	 *
3832 	 * This ensures that tasks getting woken will be fully ordered against
3833 	 * their previous state and preserve Program Order.
3834 	 */
3835 	smp_cond_load_acquire(&p->on_cpu, !VAL);
3836 
3837 	cpu = select_task_rq(p, p->wake_cpu, wake_flags | WF_TTWU);
3838 	if (task_cpu(p) != cpu) {
3839 		if (p->in_iowait) {
3840 			delayacct_blkio_end(p);
3841 			atomic_dec(&task_rq(p)->nr_iowait);
3842 		}
3843 
3844 		wake_flags |= WF_MIGRATED;
3845 		psi_ttwu_dequeue(p);
3846 		set_task_cpu(p, cpu);
3847 	}
3848 #else
3849 	cpu = task_cpu(p);
3850 #endif /* CONFIG_SMP */
3851 
3852 	ttwu_queue(p, cpu, wake_flags);
3853 unlock:
3854 	raw_spin_unlock_irqrestore(&p->pi_lock, flags);
3855 out:
3856 	if (success)
3857 		ttwu_stat(p, task_cpu(p), wake_flags);
3858 	preempt_enable();
3859 
3860 	return success;
3861 }
3862 
3863 /**
3864  * try_invoke_on_locked_down_task - Invoke a function on task in fixed state
3865  * @p: Process for which the function is to be invoked, can be @current.
3866  * @func: Function to invoke.
3867  * @arg: Argument to function.
3868  *
3869  * If the specified task can be quickly locked into a definite state
3870  * (either sleeping or on a given runqueue), arrange to keep it in that
3871  * state while invoking @func(@arg).  This function can use ->on_rq and
3872  * task_curr() to work out what the state is, if required.  Given that
3873  * @func can be invoked with a runqueue lock held, it had better be quite
3874  * lightweight.
3875  *
3876  * Returns:
3877  *	@false if the task slipped out from under the locks.
3878  *	@true if the task was locked onto a runqueue or is sleeping.
3879  *		However, @func can override this by returning @false.
3880  */
3881 bool try_invoke_on_locked_down_task(struct task_struct *p, bool (*func)(struct task_struct *t, void *arg), void *arg)
3882 {
3883 	struct rq_flags rf;
3884 	bool ret = false;
3885 	struct rq *rq;
3886 
3887 	raw_spin_lock_irqsave(&p->pi_lock, rf.flags);
3888 	if (p->on_rq) {
3889 		rq = __task_rq_lock(p, &rf);
3890 		if (task_rq(p) == rq)
3891 			ret = func(p, arg);
3892 		rq_unlock(rq, &rf);
3893 	} else {
3894 		switch (READ_ONCE(p->__state)) {
3895 		case TASK_RUNNING:
3896 		case TASK_WAKING:
3897 			break;
3898 		default:
3899 			smp_rmb(); // See smp_rmb() comment in try_to_wake_up().
3900 			if (!p->on_rq)
3901 				ret = func(p, arg);
3902 		}
3903 	}
3904 	raw_spin_unlock_irqrestore(&p->pi_lock, rf.flags);
3905 	return ret;
3906 }
3907 
3908 /**
3909  * wake_up_process - Wake up a specific process
3910  * @p: The process to be woken up.
3911  *
3912  * Attempt to wake up the nominated process and move it to the set of runnable
3913  * processes.
3914  *
3915  * Return: 1 if the process was woken up, 0 if it was already running.
3916  *
3917  * This function executes a full memory barrier before accessing the task state.
3918  */
3919 int wake_up_process(struct task_struct *p)
3920 {
3921 	return try_to_wake_up(p, TASK_NORMAL, 0);
3922 }
3923 EXPORT_SYMBOL(wake_up_process);
3924 
3925 int wake_up_state(struct task_struct *p, unsigned int state)
3926 {
3927 	return try_to_wake_up(p, state, 0);
3928 }
3929 
3930 /*
3931  * Perform scheduler related setup for a newly forked process p.
3932  * p is forked by current.
3933  *
3934  * __sched_fork() is basic setup used by init_idle() too:
3935  */
3936 static void __sched_fork(unsigned long clone_flags, struct task_struct *p)
3937 {
3938 	p->on_rq			= 0;
3939 
3940 	p->se.on_rq			= 0;
3941 	p->se.exec_start		= 0;
3942 	p->se.sum_exec_runtime		= 0;
3943 	p->se.prev_sum_exec_runtime	= 0;
3944 	p->se.nr_migrations		= 0;
3945 	p->se.vruntime			= 0;
3946 	INIT_LIST_HEAD(&p->se.group_node);
3947 
3948 #ifdef CONFIG_FAIR_GROUP_SCHED
3949 	p->se.cfs_rq			= NULL;
3950 #endif
3951 
3952 #ifdef CONFIG_SCHEDSTATS
3953 	/* Even if schedstat is disabled, there should not be garbage */
3954 	memset(&p->se.statistics, 0, sizeof(p->se.statistics));
3955 #endif
3956 
3957 	RB_CLEAR_NODE(&p->dl.rb_node);
3958 	init_dl_task_timer(&p->dl);
3959 	init_dl_inactive_task_timer(&p->dl);
3960 	__dl_clear_params(p);
3961 
3962 	INIT_LIST_HEAD(&p->rt.run_list);
3963 	p->rt.timeout		= 0;
3964 	p->rt.time_slice	= sched_rr_timeslice;
3965 	p->rt.on_rq		= 0;
3966 	p->rt.on_list		= 0;
3967 
3968 #ifdef CONFIG_PREEMPT_NOTIFIERS
3969 	INIT_HLIST_HEAD(&p->preempt_notifiers);
3970 #endif
3971 
3972 #ifdef CONFIG_COMPACTION
3973 	p->capture_control = NULL;
3974 #endif
3975 	init_numa_balancing(clone_flags, p);
3976 #ifdef CONFIG_SMP
3977 	p->wake_entry.u_flags = CSD_TYPE_TTWU;
3978 	p->migration_pending = NULL;
3979 #endif
3980 }
3981 
3982 DEFINE_STATIC_KEY_FALSE(sched_numa_balancing);
3983 
3984 #ifdef CONFIG_NUMA_BALANCING
3985 
3986 void set_numabalancing_state(bool enabled)
3987 {
3988 	if (enabled)
3989 		static_branch_enable(&sched_numa_balancing);
3990 	else
3991 		static_branch_disable(&sched_numa_balancing);
3992 }
3993 
3994 #ifdef CONFIG_PROC_SYSCTL
3995 int sysctl_numa_balancing(struct ctl_table *table, int write,
3996 			  void *buffer, size_t *lenp, loff_t *ppos)
3997 {
3998 	struct ctl_table t;
3999 	int err;
4000 	int state = static_branch_likely(&sched_numa_balancing);
4001 
4002 	if (write && !capable(CAP_SYS_ADMIN))
4003 		return -EPERM;
4004 
4005 	t = *table;
4006 	t.data = &state;
4007 	err = proc_dointvec_minmax(&t, write, buffer, lenp, ppos);
4008 	if (err < 0)
4009 		return err;
4010 	if (write)
4011 		set_numabalancing_state(state);
4012 	return err;
4013 }
4014 #endif
4015 #endif
4016 
4017 #ifdef CONFIG_SCHEDSTATS
4018 
4019 DEFINE_STATIC_KEY_FALSE(sched_schedstats);
4020 
4021 static void set_schedstats(bool enabled)
4022 {
4023 	if (enabled)
4024 		static_branch_enable(&sched_schedstats);
4025 	else
4026 		static_branch_disable(&sched_schedstats);
4027 }
4028 
4029 void force_schedstat_enabled(void)
4030 {
4031 	if (!schedstat_enabled()) {
4032 		pr_info("kernel profiling enabled schedstats, disable via kernel.sched_schedstats.\n");
4033 		static_branch_enable(&sched_schedstats);
4034 	}
4035 }
4036 
4037 static int __init setup_schedstats(char *str)
4038 {
4039 	int ret = 0;
4040 	if (!str)
4041 		goto out;
4042 
4043 	if (!strcmp(str, "enable")) {
4044 		set_schedstats(true);
4045 		ret = 1;
4046 	} else if (!strcmp(str, "disable")) {
4047 		set_schedstats(false);
4048 		ret = 1;
4049 	}
4050 out:
4051 	if (!ret)
4052 		pr_warn("Unable to parse schedstats=\n");
4053 
4054 	return ret;
4055 }
4056 __setup("schedstats=", setup_schedstats);
4057 
4058 #ifdef CONFIG_PROC_SYSCTL
4059 int sysctl_schedstats(struct ctl_table *table, int write, void *buffer,
4060 		size_t *lenp, loff_t *ppos)
4061 {
4062 	struct ctl_table t;
4063 	int err;
4064 	int state = static_branch_likely(&sched_schedstats);
4065 
4066 	if (write && !capable(CAP_SYS_ADMIN))
4067 		return -EPERM;
4068 
4069 	t = *table;
4070 	t.data = &state;
4071 	err = proc_dointvec_minmax(&t, write, buffer, lenp, ppos);
4072 	if (err < 0)
4073 		return err;
4074 	if (write)
4075 		set_schedstats(state);
4076 	return err;
4077 }
4078 #endif /* CONFIG_PROC_SYSCTL */
4079 #endif /* CONFIG_SCHEDSTATS */
4080 
4081 /*
4082  * fork()/clone()-time setup:
4083  */
4084 int sched_fork(unsigned long clone_flags, struct task_struct *p)
4085 {
4086 	unsigned long flags;
4087 
4088 	__sched_fork(clone_flags, p);
4089 	/*
4090 	 * We mark the process as NEW here. This guarantees that
4091 	 * nobody will actually run it, and a signal or other external
4092 	 * event cannot wake it up and insert it on the runqueue either.
4093 	 */
4094 	p->__state = TASK_NEW;
4095 
4096 	/*
4097 	 * Make sure we do not leak PI boosting priority to the child.
4098 	 */
4099 	p->prio = current->normal_prio;
4100 
4101 	uclamp_fork(p);
4102 
4103 	/*
4104 	 * Revert to default priority/policy on fork if requested.
4105 	 */
4106 	if (unlikely(p->sched_reset_on_fork)) {
4107 		if (task_has_dl_policy(p) || task_has_rt_policy(p)) {
4108 			p->policy = SCHED_NORMAL;
4109 			p->static_prio = NICE_TO_PRIO(0);
4110 			p->rt_priority = 0;
4111 		} else if (PRIO_TO_NICE(p->static_prio) < 0)
4112 			p->static_prio = NICE_TO_PRIO(0);
4113 
4114 		p->prio = p->normal_prio = p->static_prio;
4115 		set_load_weight(p, false);
4116 
4117 		/*
4118 		 * We don't need the reset flag anymore after the fork. It has
4119 		 * fulfilled its duty:
4120 		 */
4121 		p->sched_reset_on_fork = 0;
4122 	}
4123 
4124 	if (dl_prio(p->prio))
4125 		return -EAGAIN;
4126 	else if (rt_prio(p->prio))
4127 		p->sched_class = &rt_sched_class;
4128 	else
4129 		p->sched_class = &fair_sched_class;
4130 
4131 	init_entity_runnable_average(&p->se);
4132 
4133 	/*
4134 	 * The child is not yet in the pid-hash so no cgroup attach races,
4135 	 * and the cgroup is pinned to this child due to cgroup_fork()
4136 	 * is ran before sched_fork().
4137 	 *
4138 	 * Silence PROVE_RCU.
4139 	 */
4140 	raw_spin_lock_irqsave(&p->pi_lock, flags);
4141 	rseq_migrate(p);
4142 	/*
4143 	 * We're setting the CPU for the first time, we don't migrate,
4144 	 * so use __set_task_cpu().
4145 	 */
4146 	__set_task_cpu(p, smp_processor_id());
4147 	if (p->sched_class->task_fork)
4148 		p->sched_class->task_fork(p);
4149 	raw_spin_unlock_irqrestore(&p->pi_lock, flags);
4150 
4151 #ifdef CONFIG_SCHED_INFO
4152 	if (likely(sched_info_on()))
4153 		memset(&p->sched_info, 0, sizeof(p->sched_info));
4154 #endif
4155 #if defined(CONFIG_SMP)
4156 	p->on_cpu = 0;
4157 #endif
4158 	init_task_preempt_count(p);
4159 #ifdef CONFIG_SMP
4160 	plist_node_init(&p->pushable_tasks, MAX_PRIO);
4161 	RB_CLEAR_NODE(&p->pushable_dl_tasks);
4162 #endif
4163 	return 0;
4164 }
4165 
4166 void sched_post_fork(struct task_struct *p)
4167 {
4168 	uclamp_post_fork(p);
4169 }
4170 
4171 unsigned long to_ratio(u64 period, u64 runtime)
4172 {
4173 	if (runtime == RUNTIME_INF)
4174 		return BW_UNIT;
4175 
4176 	/*
4177 	 * Doing this here saves a lot of checks in all
4178 	 * the calling paths, and returning zero seems
4179 	 * safe for them anyway.
4180 	 */
4181 	if (period == 0)
4182 		return 0;
4183 
4184 	return div64_u64(runtime << BW_SHIFT, period);
4185 }
4186 
4187 /*
4188  * wake_up_new_task - wake up a newly created task for the first time.
4189  *
4190  * This function will do some initial scheduler statistics housekeeping
4191  * that must be done for every newly created context, then puts the task
4192  * on the runqueue and wakes it.
4193  */
4194 void wake_up_new_task(struct task_struct *p)
4195 {
4196 	struct rq_flags rf;
4197 	struct rq *rq;
4198 
4199 	raw_spin_lock_irqsave(&p->pi_lock, rf.flags);
4200 	WRITE_ONCE(p->__state, TASK_RUNNING);
4201 #ifdef CONFIG_SMP
4202 	/*
4203 	 * Fork balancing, do it here and not earlier because:
4204 	 *  - cpus_ptr can change in the fork path
4205 	 *  - any previously selected CPU might disappear through hotplug
4206 	 *
4207 	 * Use __set_task_cpu() to avoid calling sched_class::migrate_task_rq,
4208 	 * as we're not fully set-up yet.
4209 	 */
4210 	p->recent_used_cpu = task_cpu(p);
4211 	rseq_migrate(p);
4212 	__set_task_cpu(p, select_task_rq(p, task_cpu(p), WF_FORK));
4213 #endif
4214 	rq = __task_rq_lock(p, &rf);
4215 	update_rq_clock(rq);
4216 	post_init_entity_util_avg(p);
4217 
4218 	activate_task(rq, p, ENQUEUE_NOCLOCK);
4219 	trace_sched_wakeup_new(p);
4220 	check_preempt_curr(rq, p, WF_FORK);
4221 #ifdef CONFIG_SMP
4222 	if (p->sched_class->task_woken) {
4223 		/*
4224 		 * Nothing relies on rq->lock after this, so it's fine to
4225 		 * drop it.
4226 		 */
4227 		rq_unpin_lock(rq, &rf);
4228 		p->sched_class->task_woken(rq, p);
4229 		rq_repin_lock(rq, &rf);
4230 	}
4231 #endif
4232 	task_rq_unlock(rq, p, &rf);
4233 }
4234 
4235 #ifdef CONFIG_PREEMPT_NOTIFIERS
4236 
4237 static DEFINE_STATIC_KEY_FALSE(preempt_notifier_key);
4238 
4239 void preempt_notifier_inc(void)
4240 {
4241 	static_branch_inc(&preempt_notifier_key);
4242 }
4243 EXPORT_SYMBOL_GPL(preempt_notifier_inc);
4244 
4245 void preempt_notifier_dec(void)
4246 {
4247 	static_branch_dec(&preempt_notifier_key);
4248 }
4249 EXPORT_SYMBOL_GPL(preempt_notifier_dec);
4250 
4251 /**
4252  * preempt_notifier_register - tell me when current is being preempted & rescheduled
4253  * @notifier: notifier struct to register
4254  */
4255 void preempt_notifier_register(struct preempt_notifier *notifier)
4256 {
4257 	if (!static_branch_unlikely(&preempt_notifier_key))
4258 		WARN(1, "registering preempt_notifier while notifiers disabled\n");
4259 
4260 	hlist_add_head(&notifier->link, &current->preempt_notifiers);
4261 }
4262 EXPORT_SYMBOL_GPL(preempt_notifier_register);
4263 
4264 /**
4265  * preempt_notifier_unregister - no longer interested in preemption notifications
4266  * @notifier: notifier struct to unregister
4267  *
4268  * This is *not* safe to call from within a preemption notifier.
4269  */
4270 void preempt_notifier_unregister(struct preempt_notifier *notifier)
4271 {
4272 	hlist_del(&notifier->link);
4273 }
4274 EXPORT_SYMBOL_GPL(preempt_notifier_unregister);
4275 
4276 static void __fire_sched_in_preempt_notifiers(struct task_struct *curr)
4277 {
4278 	struct preempt_notifier *notifier;
4279 
4280 	hlist_for_each_entry(notifier, &curr->preempt_notifiers, link)
4281 		notifier->ops->sched_in(notifier, raw_smp_processor_id());
4282 }
4283 
4284 static __always_inline void fire_sched_in_preempt_notifiers(struct task_struct *curr)
4285 {
4286 	if (static_branch_unlikely(&preempt_notifier_key))
4287 		__fire_sched_in_preempt_notifiers(curr);
4288 }
4289 
4290 static void
4291 __fire_sched_out_preempt_notifiers(struct task_struct *curr,
4292 				   struct task_struct *next)
4293 {
4294 	struct preempt_notifier *notifier;
4295 
4296 	hlist_for_each_entry(notifier, &curr->preempt_notifiers, link)
4297 		notifier->ops->sched_out(notifier, next);
4298 }
4299 
4300 static __always_inline void
4301 fire_sched_out_preempt_notifiers(struct task_struct *curr,
4302 				 struct task_struct *next)
4303 {
4304 	if (static_branch_unlikely(&preempt_notifier_key))
4305 		__fire_sched_out_preempt_notifiers(curr, next);
4306 }
4307 
4308 #else /* !CONFIG_PREEMPT_NOTIFIERS */
4309 
4310 static inline void fire_sched_in_preempt_notifiers(struct task_struct *curr)
4311 {
4312 }
4313 
4314 static inline void
4315 fire_sched_out_preempt_notifiers(struct task_struct *curr,
4316 				 struct task_struct *next)
4317 {
4318 }
4319 
4320 #endif /* CONFIG_PREEMPT_NOTIFIERS */
4321 
4322 static inline void prepare_task(struct task_struct *next)
4323 {
4324 #ifdef CONFIG_SMP
4325 	/*
4326 	 * Claim the task as running, we do this before switching to it
4327 	 * such that any running task will have this set.
4328 	 *
4329 	 * See the ttwu() WF_ON_CPU case and its ordering comment.
4330 	 */
4331 	WRITE_ONCE(next->on_cpu, 1);
4332 #endif
4333 }
4334 
4335 static inline void finish_task(struct task_struct *prev)
4336 {
4337 #ifdef CONFIG_SMP
4338 	/*
4339 	 * This must be the very last reference to @prev from this CPU. After
4340 	 * p->on_cpu is cleared, the task can be moved to a different CPU. We
4341 	 * must ensure this doesn't happen until the switch is completely
4342 	 * finished.
4343 	 *
4344 	 * In particular, the load of prev->state in finish_task_switch() must
4345 	 * happen before this.
4346 	 *
4347 	 * Pairs with the smp_cond_load_acquire() in try_to_wake_up().
4348 	 */
4349 	smp_store_release(&prev->on_cpu, 0);
4350 #endif
4351 }
4352 
4353 #ifdef CONFIG_SMP
4354 
4355 static void do_balance_callbacks(struct rq *rq, struct callback_head *head)
4356 {
4357 	void (*func)(struct rq *rq);
4358 	struct callback_head *next;
4359 
4360 	lockdep_assert_rq_held(rq);
4361 
4362 	while (head) {
4363 		func = (void (*)(struct rq *))head->func;
4364 		next = head->next;
4365 		head->next = NULL;
4366 		head = next;
4367 
4368 		func(rq);
4369 	}
4370 }
4371 
4372 static void balance_push(struct rq *rq);
4373 
4374 struct callback_head balance_push_callback = {
4375 	.next = NULL,
4376 	.func = (void (*)(struct callback_head *))balance_push,
4377 };
4378 
4379 static inline struct callback_head *splice_balance_callbacks(struct rq *rq)
4380 {
4381 	struct callback_head *head = rq->balance_callback;
4382 
4383 	lockdep_assert_rq_held(rq);
4384 	if (head)
4385 		rq->balance_callback = NULL;
4386 
4387 	return head;
4388 }
4389 
4390 static void __balance_callbacks(struct rq *rq)
4391 {
4392 	do_balance_callbacks(rq, splice_balance_callbacks(rq));
4393 }
4394 
4395 static inline void balance_callbacks(struct rq *rq, struct callback_head *head)
4396 {
4397 	unsigned long flags;
4398 
4399 	if (unlikely(head)) {
4400 		raw_spin_rq_lock_irqsave(rq, flags);
4401 		do_balance_callbacks(rq, head);
4402 		raw_spin_rq_unlock_irqrestore(rq, flags);
4403 	}
4404 }
4405 
4406 #else
4407 
4408 static inline void __balance_callbacks(struct rq *rq)
4409 {
4410 }
4411 
4412 static inline struct callback_head *splice_balance_callbacks(struct rq *rq)
4413 {
4414 	return NULL;
4415 }
4416 
4417 static inline void balance_callbacks(struct rq *rq, struct callback_head *head)
4418 {
4419 }
4420 
4421 #endif
4422 
4423 static inline void
4424 prepare_lock_switch(struct rq *rq, struct task_struct *next, struct rq_flags *rf)
4425 {
4426 	/*
4427 	 * Since the runqueue lock will be released by the next
4428 	 * task (which is an invalid locking op but in the case
4429 	 * of the scheduler it's an obvious special-case), so we
4430 	 * do an early lockdep release here:
4431 	 */
4432 	rq_unpin_lock(rq, rf);
4433 	spin_release(&__rq_lockp(rq)->dep_map, _THIS_IP_);
4434 #ifdef CONFIG_DEBUG_SPINLOCK
4435 	/* this is a valid case when another task releases the spinlock */
4436 	rq_lockp(rq)->owner = next;
4437 #endif
4438 }
4439 
4440 static inline void finish_lock_switch(struct rq *rq)
4441 {
4442 	/*
4443 	 * If we are tracking spinlock dependencies then we have to
4444 	 * fix up the runqueue lock - which gets 'carried over' from
4445 	 * prev into current:
4446 	 */
4447 	spin_acquire(&__rq_lockp(rq)->dep_map, 0, 0, _THIS_IP_);
4448 	__balance_callbacks(rq);
4449 	raw_spin_rq_unlock_irq(rq);
4450 }
4451 
4452 /*
4453  * NOP if the arch has not defined these:
4454  */
4455 
4456 #ifndef prepare_arch_switch
4457 # define prepare_arch_switch(next)	do { } while (0)
4458 #endif
4459 
4460 #ifndef finish_arch_post_lock_switch
4461 # define finish_arch_post_lock_switch()	do { } while (0)
4462 #endif
4463 
4464 static inline void kmap_local_sched_out(void)
4465 {
4466 #ifdef CONFIG_KMAP_LOCAL
4467 	if (unlikely(current->kmap_ctrl.idx))
4468 		__kmap_local_sched_out();
4469 #endif
4470 }
4471 
4472 static inline void kmap_local_sched_in(void)
4473 {
4474 #ifdef CONFIG_KMAP_LOCAL
4475 	if (unlikely(current->kmap_ctrl.idx))
4476 		__kmap_local_sched_in();
4477 #endif
4478 }
4479 
4480 /**
4481  * prepare_task_switch - prepare to switch tasks
4482  * @rq: the runqueue preparing to switch
4483  * @prev: the current task that is being switched out
4484  * @next: the task we are going to switch to.
4485  *
4486  * This is called with the rq lock held and interrupts off. It must
4487  * be paired with a subsequent finish_task_switch after the context
4488  * switch.
4489  *
4490  * prepare_task_switch sets up locking and calls architecture specific
4491  * hooks.
4492  */
4493 static inline void
4494 prepare_task_switch(struct rq *rq, struct task_struct *prev,
4495 		    struct task_struct *next)
4496 {
4497 	kcov_prepare_switch(prev);
4498 	sched_info_switch(rq, prev, next);
4499 	perf_event_task_sched_out(prev, next);
4500 	rseq_preempt(prev);
4501 	fire_sched_out_preempt_notifiers(prev, next);
4502 	kmap_local_sched_out();
4503 	prepare_task(next);
4504 	prepare_arch_switch(next);
4505 }
4506 
4507 /**
4508  * finish_task_switch - clean up after a task-switch
4509  * @prev: the thread we just switched away from.
4510  *
4511  * finish_task_switch must be called after the context switch, paired
4512  * with a prepare_task_switch call before the context switch.
4513  * finish_task_switch will reconcile locking set up by prepare_task_switch,
4514  * and do any other architecture-specific cleanup actions.
4515  *
4516  * Note that we may have delayed dropping an mm in context_switch(). If
4517  * so, we finish that here outside of the runqueue lock. (Doing it
4518  * with the lock held can cause deadlocks; see schedule() for
4519  * details.)
4520  *
4521  * The context switch have flipped the stack from under us and restored the
4522  * local variables which were saved when this task called schedule() in the
4523  * past. prev == current is still correct but we need to recalculate this_rq
4524  * because prev may have moved to another CPU.
4525  */
4526 static struct rq *finish_task_switch(struct task_struct *prev)
4527 	__releases(rq->lock)
4528 {
4529 	struct rq *rq = this_rq();
4530 	struct mm_struct *mm = rq->prev_mm;
4531 	long prev_state;
4532 
4533 	/*
4534 	 * The previous task will have left us with a preempt_count of 2
4535 	 * because it left us after:
4536 	 *
4537 	 *	schedule()
4538 	 *	  preempt_disable();			// 1
4539 	 *	  __schedule()
4540 	 *	    raw_spin_lock_irq(&rq->lock)	// 2
4541 	 *
4542 	 * Also, see FORK_PREEMPT_COUNT.
4543 	 */
4544 	if (WARN_ONCE(preempt_count() != 2*PREEMPT_DISABLE_OFFSET,
4545 		      "corrupted preempt_count: %s/%d/0x%x\n",
4546 		      current->comm, current->pid, preempt_count()))
4547 		preempt_count_set(FORK_PREEMPT_COUNT);
4548 
4549 	rq->prev_mm = NULL;
4550 
4551 	/*
4552 	 * A task struct has one reference for the use as "current".
4553 	 * If a task dies, then it sets TASK_DEAD in tsk->state and calls
4554 	 * schedule one last time. The schedule call will never return, and
4555 	 * the scheduled task must drop that reference.
4556 	 *
4557 	 * We must observe prev->state before clearing prev->on_cpu (in
4558 	 * finish_task), otherwise a concurrent wakeup can get prev
4559 	 * running on another CPU and we could rave with its RUNNING -> DEAD
4560 	 * transition, resulting in a double drop.
4561 	 */
4562 	prev_state = READ_ONCE(prev->__state);
4563 	vtime_task_switch(prev);
4564 	perf_event_task_sched_in(prev, current);
4565 	finish_task(prev);
4566 	tick_nohz_task_switch();
4567 	finish_lock_switch(rq);
4568 	finish_arch_post_lock_switch();
4569 	kcov_finish_switch(current);
4570 	/*
4571 	 * kmap_local_sched_out() is invoked with rq::lock held and
4572 	 * interrupts disabled. There is no requirement for that, but the
4573 	 * sched out code does not have an interrupt enabled section.
4574 	 * Restoring the maps on sched in does not require interrupts being
4575 	 * disabled either.
4576 	 */
4577 	kmap_local_sched_in();
4578 
4579 	fire_sched_in_preempt_notifiers(current);
4580 	/*
4581 	 * When switching through a kernel thread, the loop in
4582 	 * membarrier_{private,global}_expedited() may have observed that
4583 	 * kernel thread and not issued an IPI. It is therefore possible to
4584 	 * schedule between user->kernel->user threads without passing though
4585 	 * switch_mm(). Membarrier requires a barrier after storing to
4586 	 * rq->curr, before returning to userspace, so provide them here:
4587 	 *
4588 	 * - a full memory barrier for {PRIVATE,GLOBAL}_EXPEDITED, implicitly
4589 	 *   provided by mmdrop(),
4590 	 * - a sync_core for SYNC_CORE.
4591 	 */
4592 	if (mm) {
4593 		membarrier_mm_sync_core_before_usermode(mm);
4594 		mmdrop(mm);
4595 	}
4596 	if (unlikely(prev_state == TASK_DEAD)) {
4597 		if (prev->sched_class->task_dead)
4598 			prev->sched_class->task_dead(prev);
4599 
4600 		/*
4601 		 * Remove function-return probe instances associated with this
4602 		 * task and put them back on the free list.
4603 		 */
4604 		kprobe_flush_task(prev);
4605 
4606 		/* Task is done with its stack. */
4607 		put_task_stack(prev);
4608 
4609 		put_task_struct_rcu_user(prev);
4610 	}
4611 
4612 	return rq;
4613 }
4614 
4615 /**
4616  * schedule_tail - first thing a freshly forked thread must call.
4617  * @prev: the thread we just switched away from.
4618  */
4619 asmlinkage __visible void schedule_tail(struct task_struct *prev)
4620 	__releases(rq->lock)
4621 {
4622 	/*
4623 	 * New tasks start with FORK_PREEMPT_COUNT, see there and
4624 	 * finish_task_switch() for details.
4625 	 *
4626 	 * finish_task_switch() will drop rq->lock() and lower preempt_count
4627 	 * and the preempt_enable() will end up enabling preemption (on
4628 	 * PREEMPT_COUNT kernels).
4629 	 */
4630 
4631 	finish_task_switch(prev);
4632 	preempt_enable();
4633 
4634 	if (current->set_child_tid)
4635 		put_user(task_pid_vnr(current), current->set_child_tid);
4636 
4637 	calculate_sigpending();
4638 }
4639 
4640 /*
4641  * context_switch - switch to the new MM and the new thread's register state.
4642  */
4643 static __always_inline struct rq *
4644 context_switch(struct rq *rq, struct task_struct *prev,
4645 	       struct task_struct *next, struct rq_flags *rf)
4646 {
4647 	prepare_task_switch(rq, prev, next);
4648 
4649 	/*
4650 	 * For paravirt, this is coupled with an exit in switch_to to
4651 	 * combine the page table reload and the switch backend into
4652 	 * one hypercall.
4653 	 */
4654 	arch_start_context_switch(prev);
4655 
4656 	/*
4657 	 * kernel -> kernel   lazy + transfer active
4658 	 *   user -> kernel   lazy + mmgrab() active
4659 	 *
4660 	 * kernel ->   user   switch + mmdrop() active
4661 	 *   user ->   user   switch
4662 	 */
4663 	if (!next->mm) {                                // to kernel
4664 		enter_lazy_tlb(prev->active_mm, next);
4665 
4666 		next->active_mm = prev->active_mm;
4667 		if (prev->mm)                           // from user
4668 			mmgrab(prev->active_mm);
4669 		else
4670 			prev->active_mm = NULL;
4671 	} else {                                        // to user
4672 		membarrier_switch_mm(rq, prev->active_mm, next->mm);
4673 		/*
4674 		 * sys_membarrier() requires an smp_mb() between setting
4675 		 * rq->curr / membarrier_switch_mm() and returning to userspace.
4676 		 *
4677 		 * The below provides this either through switch_mm(), or in
4678 		 * case 'prev->active_mm == next->mm' through
4679 		 * finish_task_switch()'s mmdrop().
4680 		 */
4681 		switch_mm_irqs_off(prev->active_mm, next->mm, next);
4682 
4683 		if (!prev->mm) {                        // from kernel
4684 			/* will mmdrop() in finish_task_switch(). */
4685 			rq->prev_mm = prev->active_mm;
4686 			prev->active_mm = NULL;
4687 		}
4688 	}
4689 
4690 	rq->clock_update_flags &= ~(RQCF_ACT_SKIP|RQCF_REQ_SKIP);
4691 
4692 	prepare_lock_switch(rq, next, rf);
4693 
4694 	/* Here we just switch the register state and the stack. */
4695 	switch_to(prev, next, prev);
4696 	barrier();
4697 
4698 	return finish_task_switch(prev);
4699 }
4700 
4701 /*
4702  * nr_running and nr_context_switches:
4703  *
4704  * externally visible scheduler statistics: current number of runnable
4705  * threads, total number of context switches performed since bootup.
4706  */
4707 unsigned int nr_running(void)
4708 {
4709 	unsigned int i, sum = 0;
4710 
4711 	for_each_online_cpu(i)
4712 		sum += cpu_rq(i)->nr_running;
4713 
4714 	return sum;
4715 }
4716 
4717 /*
4718  * Check if only the current task is running on the CPU.
4719  *
4720  * Caution: this function does not check that the caller has disabled
4721  * preemption, thus the result might have a time-of-check-to-time-of-use
4722  * race.  The caller is responsible to use it correctly, for example:
4723  *
4724  * - from a non-preemptible section (of course)
4725  *
4726  * - from a thread that is bound to a single CPU
4727  *
4728  * - in a loop with very short iterations (e.g. a polling loop)
4729  */
4730 bool single_task_running(void)
4731 {
4732 	return raw_rq()->nr_running == 1;
4733 }
4734 EXPORT_SYMBOL(single_task_running);
4735 
4736 unsigned long long nr_context_switches(void)
4737 {
4738 	int i;
4739 	unsigned long long sum = 0;
4740 
4741 	for_each_possible_cpu(i)
4742 		sum += cpu_rq(i)->nr_switches;
4743 
4744 	return sum;
4745 }
4746 
4747 /*
4748  * Consumers of these two interfaces, like for example the cpuidle menu
4749  * governor, are using nonsensical data. Preferring shallow idle state selection
4750  * for a CPU that has IO-wait which might not even end up running the task when
4751  * it does become runnable.
4752  */
4753 
4754 unsigned int nr_iowait_cpu(int cpu)
4755 {
4756 	return atomic_read(&cpu_rq(cpu)->nr_iowait);
4757 }
4758 
4759 /*
4760  * IO-wait accounting, and how it's mostly bollocks (on SMP).
4761  *
4762  * The idea behind IO-wait account is to account the idle time that we could
4763  * have spend running if it were not for IO. That is, if we were to improve the
4764  * storage performance, we'd have a proportional reduction in IO-wait time.
4765  *
4766  * This all works nicely on UP, where, when a task blocks on IO, we account
4767  * idle time as IO-wait, because if the storage were faster, it could've been
4768  * running and we'd not be idle.
4769  *
4770  * This has been extended to SMP, by doing the same for each CPU. This however
4771  * is broken.
4772  *
4773  * Imagine for instance the case where two tasks block on one CPU, only the one
4774  * CPU will have IO-wait accounted, while the other has regular idle. Even
4775  * though, if the storage were faster, both could've ran at the same time,
4776  * utilising both CPUs.
4777  *
4778  * This means, that when looking globally, the current IO-wait accounting on
4779  * SMP is a lower bound, by reason of under accounting.
4780  *
4781  * Worse, since the numbers are provided per CPU, they are sometimes
4782  * interpreted per CPU, and that is nonsensical. A blocked task isn't strictly
4783  * associated with any one particular CPU, it can wake to another CPU than it
4784  * blocked on. This means the per CPU IO-wait number is meaningless.
4785  *
4786  * Task CPU affinities can make all that even more 'interesting'.
4787  */
4788 
4789 unsigned int nr_iowait(void)
4790 {
4791 	unsigned int i, sum = 0;
4792 
4793 	for_each_possible_cpu(i)
4794 		sum += nr_iowait_cpu(i);
4795 
4796 	return sum;
4797 }
4798 
4799 #ifdef CONFIG_SMP
4800 
4801 /*
4802  * sched_exec - execve() is a valuable balancing opportunity, because at
4803  * this point the task has the smallest effective memory and cache footprint.
4804  */
4805 void sched_exec(void)
4806 {
4807 	struct task_struct *p = current;
4808 	unsigned long flags;
4809 	int dest_cpu;
4810 
4811 	raw_spin_lock_irqsave(&p->pi_lock, flags);
4812 	dest_cpu = p->sched_class->select_task_rq(p, task_cpu(p), WF_EXEC);
4813 	if (dest_cpu == smp_processor_id())
4814 		goto unlock;
4815 
4816 	if (likely(cpu_active(dest_cpu))) {
4817 		struct migration_arg arg = { p, dest_cpu };
4818 
4819 		raw_spin_unlock_irqrestore(&p->pi_lock, flags);
4820 		stop_one_cpu(task_cpu(p), migration_cpu_stop, &arg);
4821 		return;
4822 	}
4823 unlock:
4824 	raw_spin_unlock_irqrestore(&p->pi_lock, flags);
4825 }
4826 
4827 #endif
4828 
4829 DEFINE_PER_CPU(struct kernel_stat, kstat);
4830 DEFINE_PER_CPU(struct kernel_cpustat, kernel_cpustat);
4831 
4832 EXPORT_PER_CPU_SYMBOL(kstat);
4833 EXPORT_PER_CPU_SYMBOL(kernel_cpustat);
4834 
4835 /*
4836  * The function fair_sched_class.update_curr accesses the struct curr
4837  * and its field curr->exec_start; when called from task_sched_runtime(),
4838  * we observe a high rate of cache misses in practice.
4839  * Prefetching this data results in improved performance.
4840  */
4841 static inline void prefetch_curr_exec_start(struct task_struct *p)
4842 {
4843 #ifdef CONFIG_FAIR_GROUP_SCHED
4844 	struct sched_entity *curr = (&p->se)->cfs_rq->curr;
4845 #else
4846 	struct sched_entity *curr = (&task_rq(p)->cfs)->curr;
4847 #endif
4848 	prefetch(curr);
4849 	prefetch(&curr->exec_start);
4850 }
4851 
4852 /*
4853  * Return accounted runtime for the task.
4854  * In case the task is currently running, return the runtime plus current's
4855  * pending runtime that have not been accounted yet.
4856  */
4857 unsigned long long task_sched_runtime(struct task_struct *p)
4858 {
4859 	struct rq_flags rf;
4860 	struct rq *rq;
4861 	u64 ns;
4862 
4863 #if defined(CONFIG_64BIT) && defined(CONFIG_SMP)
4864 	/*
4865 	 * 64-bit doesn't need locks to atomically read a 64-bit value.
4866 	 * So we have a optimization chance when the task's delta_exec is 0.
4867 	 * Reading ->on_cpu is racy, but this is ok.
4868 	 *
4869 	 * If we race with it leaving CPU, we'll take a lock. So we're correct.
4870 	 * If we race with it entering CPU, unaccounted time is 0. This is
4871 	 * indistinguishable from the read occurring a few cycles earlier.
4872 	 * If we see ->on_cpu without ->on_rq, the task is leaving, and has
4873 	 * been accounted, so we're correct here as well.
4874 	 */
4875 	if (!p->on_cpu || !task_on_rq_queued(p))
4876 		return p->se.sum_exec_runtime;
4877 #endif
4878 
4879 	rq = task_rq_lock(p, &rf);
4880 	/*
4881 	 * Must be ->curr _and_ ->on_rq.  If dequeued, we would
4882 	 * project cycles that may never be accounted to this
4883 	 * thread, breaking clock_gettime().
4884 	 */
4885 	if (task_current(rq, p) && task_on_rq_queued(p)) {
4886 		prefetch_curr_exec_start(p);
4887 		update_rq_clock(rq);
4888 		p->sched_class->update_curr(rq);
4889 	}
4890 	ns = p->se.sum_exec_runtime;
4891 	task_rq_unlock(rq, p, &rf);
4892 
4893 	return ns;
4894 }
4895 
4896 #ifdef CONFIG_SCHED_DEBUG
4897 static u64 cpu_resched_latency(struct rq *rq)
4898 {
4899 	int latency_warn_ms = READ_ONCE(sysctl_resched_latency_warn_ms);
4900 	u64 resched_latency, now = rq_clock(rq);
4901 	static bool warned_once;
4902 
4903 	if (sysctl_resched_latency_warn_once && warned_once)
4904 		return 0;
4905 
4906 	if (!need_resched() || !latency_warn_ms)
4907 		return 0;
4908 
4909 	if (system_state == SYSTEM_BOOTING)
4910 		return 0;
4911 
4912 	if (!rq->last_seen_need_resched_ns) {
4913 		rq->last_seen_need_resched_ns = now;
4914 		rq->ticks_without_resched = 0;
4915 		return 0;
4916 	}
4917 
4918 	rq->ticks_without_resched++;
4919 	resched_latency = now - rq->last_seen_need_resched_ns;
4920 	if (resched_latency <= latency_warn_ms * NSEC_PER_MSEC)
4921 		return 0;
4922 
4923 	warned_once = true;
4924 
4925 	return resched_latency;
4926 }
4927 
4928 static int __init setup_resched_latency_warn_ms(char *str)
4929 {
4930 	long val;
4931 
4932 	if ((kstrtol(str, 0, &val))) {
4933 		pr_warn("Unable to set resched_latency_warn_ms\n");
4934 		return 1;
4935 	}
4936 
4937 	sysctl_resched_latency_warn_ms = val;
4938 	return 1;
4939 }
4940 __setup("resched_latency_warn_ms=", setup_resched_latency_warn_ms);
4941 #else
4942 static inline u64 cpu_resched_latency(struct rq *rq) { return 0; }
4943 #endif /* CONFIG_SCHED_DEBUG */
4944 
4945 /*
4946  * This function gets called by the timer code, with HZ frequency.
4947  * We call it with interrupts disabled.
4948  */
4949 void scheduler_tick(void)
4950 {
4951 	int cpu = smp_processor_id();
4952 	struct rq *rq = cpu_rq(cpu);
4953 	struct task_struct *curr = rq->curr;
4954 	struct rq_flags rf;
4955 	unsigned long thermal_pressure;
4956 	u64 resched_latency;
4957 
4958 	arch_scale_freq_tick();
4959 	sched_clock_tick();
4960 
4961 	rq_lock(rq, &rf);
4962 
4963 	update_rq_clock(rq);
4964 	thermal_pressure = arch_scale_thermal_pressure(cpu_of(rq));
4965 	update_thermal_load_avg(rq_clock_thermal(rq), rq, thermal_pressure);
4966 	curr->sched_class->task_tick(rq, curr, 0);
4967 	if (sched_feat(LATENCY_WARN))
4968 		resched_latency = cpu_resched_latency(rq);
4969 	calc_global_load_tick(rq);
4970 
4971 	rq_unlock(rq, &rf);
4972 
4973 	if (sched_feat(LATENCY_WARN) && resched_latency)
4974 		resched_latency_warn(cpu, resched_latency);
4975 
4976 	perf_event_task_tick();
4977 
4978 #ifdef CONFIG_SMP
4979 	rq->idle_balance = idle_cpu(cpu);
4980 	trigger_load_balance(rq);
4981 #endif
4982 }
4983 
4984 #ifdef CONFIG_NO_HZ_FULL
4985 
4986 struct tick_work {
4987 	int			cpu;
4988 	atomic_t		state;
4989 	struct delayed_work	work;
4990 };
4991 /* Values for ->state, see diagram below. */
4992 #define TICK_SCHED_REMOTE_OFFLINE	0
4993 #define TICK_SCHED_REMOTE_OFFLINING	1
4994 #define TICK_SCHED_REMOTE_RUNNING	2
4995 
4996 /*
4997  * State diagram for ->state:
4998  *
4999  *
5000  *          TICK_SCHED_REMOTE_OFFLINE
5001  *                    |   ^
5002  *                    |   |
5003  *                    |   | sched_tick_remote()
5004  *                    |   |
5005  *                    |   |
5006  *                    +--TICK_SCHED_REMOTE_OFFLINING
5007  *                    |   ^
5008  *                    |   |
5009  * sched_tick_start() |   | sched_tick_stop()
5010  *                    |   |
5011  *                    V   |
5012  *          TICK_SCHED_REMOTE_RUNNING
5013  *
5014  *
5015  * Other transitions get WARN_ON_ONCE(), except that sched_tick_remote()
5016  * and sched_tick_start() are happy to leave the state in RUNNING.
5017  */
5018 
5019 static struct tick_work __percpu *tick_work_cpu;
5020 
5021 static void sched_tick_remote(struct work_struct *work)
5022 {
5023 	struct delayed_work *dwork = to_delayed_work(work);
5024 	struct tick_work *twork = container_of(dwork, struct tick_work, work);
5025 	int cpu = twork->cpu;
5026 	struct rq *rq = cpu_rq(cpu);
5027 	struct task_struct *curr;
5028 	struct rq_flags rf;
5029 	u64 delta;
5030 	int os;
5031 
5032 	/*
5033 	 * Handle the tick only if it appears the remote CPU is running in full
5034 	 * dynticks mode. The check is racy by nature, but missing a tick or
5035 	 * having one too much is no big deal because the scheduler tick updates
5036 	 * statistics and checks timeslices in a time-independent way, regardless
5037 	 * of when exactly it is running.
5038 	 */
5039 	if (!tick_nohz_tick_stopped_cpu(cpu))
5040 		goto out_requeue;
5041 
5042 	rq_lock_irq(rq, &rf);
5043 	curr = rq->curr;
5044 	if (cpu_is_offline(cpu))
5045 		goto out_unlock;
5046 
5047 	update_rq_clock(rq);
5048 
5049 	if (!is_idle_task(curr)) {
5050 		/*
5051 		 * Make sure the next tick runs within a reasonable
5052 		 * amount of time.
5053 		 */
5054 		delta = rq_clock_task(rq) - curr->se.exec_start;
5055 		WARN_ON_ONCE(delta > (u64)NSEC_PER_SEC * 3);
5056 	}
5057 	curr->sched_class->task_tick(rq, curr, 0);
5058 
5059 	calc_load_nohz_remote(rq);
5060 out_unlock:
5061 	rq_unlock_irq(rq, &rf);
5062 out_requeue:
5063 
5064 	/*
5065 	 * Run the remote tick once per second (1Hz). This arbitrary
5066 	 * frequency is large enough to avoid overload but short enough
5067 	 * to keep scheduler internal stats reasonably up to date.  But
5068 	 * first update state to reflect hotplug activity if required.
5069 	 */
5070 	os = atomic_fetch_add_unless(&twork->state, -1, TICK_SCHED_REMOTE_RUNNING);
5071 	WARN_ON_ONCE(os == TICK_SCHED_REMOTE_OFFLINE);
5072 	if (os == TICK_SCHED_REMOTE_RUNNING)
5073 		queue_delayed_work(system_unbound_wq, dwork, HZ);
5074 }
5075 
5076 static void sched_tick_start(int cpu)
5077 {
5078 	int os;
5079 	struct tick_work *twork;
5080 
5081 	if (housekeeping_cpu(cpu, HK_FLAG_TICK))
5082 		return;
5083 
5084 	WARN_ON_ONCE(!tick_work_cpu);
5085 
5086 	twork = per_cpu_ptr(tick_work_cpu, cpu);
5087 	os = atomic_xchg(&twork->state, TICK_SCHED_REMOTE_RUNNING);
5088 	WARN_ON_ONCE(os == TICK_SCHED_REMOTE_RUNNING);
5089 	if (os == TICK_SCHED_REMOTE_OFFLINE) {
5090 		twork->cpu = cpu;
5091 		INIT_DELAYED_WORK(&twork->work, sched_tick_remote);
5092 		queue_delayed_work(system_unbound_wq, &twork->work, HZ);
5093 	}
5094 }
5095 
5096 #ifdef CONFIG_HOTPLUG_CPU
5097 static void sched_tick_stop(int cpu)
5098 {
5099 	struct tick_work *twork;
5100 	int os;
5101 
5102 	if (housekeeping_cpu(cpu, HK_FLAG_TICK))
5103 		return;
5104 
5105 	WARN_ON_ONCE(!tick_work_cpu);
5106 
5107 	twork = per_cpu_ptr(tick_work_cpu, cpu);
5108 	/* There cannot be competing actions, but don't rely on stop-machine. */
5109 	os = atomic_xchg(&twork->state, TICK_SCHED_REMOTE_OFFLINING);
5110 	WARN_ON_ONCE(os != TICK_SCHED_REMOTE_RUNNING);
5111 	/* Don't cancel, as this would mess up the state machine. */
5112 }
5113 #endif /* CONFIG_HOTPLUG_CPU */
5114 
5115 int __init sched_tick_offload_init(void)
5116 {
5117 	tick_work_cpu = alloc_percpu(struct tick_work);
5118 	BUG_ON(!tick_work_cpu);
5119 	return 0;
5120 }
5121 
5122 #else /* !CONFIG_NO_HZ_FULL */
5123 static inline void sched_tick_start(int cpu) { }
5124 static inline void sched_tick_stop(int cpu) { }
5125 #endif
5126 
5127 #if defined(CONFIG_PREEMPTION) && (defined(CONFIG_DEBUG_PREEMPT) || \
5128 				defined(CONFIG_TRACE_PREEMPT_TOGGLE))
5129 /*
5130  * If the value passed in is equal to the current preempt count
5131  * then we just disabled preemption. Start timing the latency.
5132  */
5133 static inline void preempt_latency_start(int val)
5134 {
5135 	if (preempt_count() == val) {
5136 		unsigned long ip = get_lock_parent_ip();
5137 #ifdef CONFIG_DEBUG_PREEMPT
5138 		current->preempt_disable_ip = ip;
5139 #endif
5140 		trace_preempt_off(CALLER_ADDR0, ip);
5141 	}
5142 }
5143 
5144 void preempt_count_add(int val)
5145 {
5146 #ifdef CONFIG_DEBUG_PREEMPT
5147 	/*
5148 	 * Underflow?
5149 	 */
5150 	if (DEBUG_LOCKS_WARN_ON((preempt_count() < 0)))
5151 		return;
5152 #endif
5153 	__preempt_count_add(val);
5154 #ifdef CONFIG_DEBUG_PREEMPT
5155 	/*
5156 	 * Spinlock count overflowing soon?
5157 	 */
5158 	DEBUG_LOCKS_WARN_ON((preempt_count() & PREEMPT_MASK) >=
5159 				PREEMPT_MASK - 10);
5160 #endif
5161 	preempt_latency_start(val);
5162 }
5163 EXPORT_SYMBOL(preempt_count_add);
5164 NOKPROBE_SYMBOL(preempt_count_add);
5165 
5166 /*
5167  * If the value passed in equals to the current preempt count
5168  * then we just enabled preemption. Stop timing the latency.
5169  */
5170 static inline void preempt_latency_stop(int val)
5171 {
5172 	if (preempt_count() == val)
5173 		trace_preempt_on(CALLER_ADDR0, get_lock_parent_ip());
5174 }
5175 
5176 void preempt_count_sub(int val)
5177 {
5178 #ifdef CONFIG_DEBUG_PREEMPT
5179 	/*
5180 	 * Underflow?
5181 	 */
5182 	if (DEBUG_LOCKS_WARN_ON(val > preempt_count()))
5183 		return;
5184 	/*
5185 	 * Is the spinlock portion underflowing?
5186 	 */
5187 	if (DEBUG_LOCKS_WARN_ON((val < PREEMPT_MASK) &&
5188 			!(preempt_count() & PREEMPT_MASK)))
5189 		return;
5190 #endif
5191 
5192 	preempt_latency_stop(val);
5193 	__preempt_count_sub(val);
5194 }
5195 EXPORT_SYMBOL(preempt_count_sub);
5196 NOKPROBE_SYMBOL(preempt_count_sub);
5197 
5198 #else
5199 static inline void preempt_latency_start(int val) { }
5200 static inline void preempt_latency_stop(int val) { }
5201 #endif
5202 
5203 static inline unsigned long get_preempt_disable_ip(struct task_struct *p)
5204 {
5205 #ifdef CONFIG_DEBUG_PREEMPT
5206 	return p->preempt_disable_ip;
5207 #else
5208 	return 0;
5209 #endif
5210 }
5211 
5212 /*
5213  * Print scheduling while atomic bug:
5214  */
5215 static noinline void __schedule_bug(struct task_struct *prev)
5216 {
5217 	/* Save this before calling printk(), since that will clobber it */
5218 	unsigned long preempt_disable_ip = get_preempt_disable_ip(current);
5219 
5220 	if (oops_in_progress)
5221 		return;
5222 
5223 	printk(KERN_ERR "BUG: scheduling while atomic: %s/%d/0x%08x\n",
5224 		prev->comm, prev->pid, preempt_count());
5225 
5226 	debug_show_held_locks(prev);
5227 	print_modules();
5228 	if (irqs_disabled())
5229 		print_irqtrace_events(prev);
5230 	if (IS_ENABLED(CONFIG_DEBUG_PREEMPT)
5231 	    && in_atomic_preempt_off()) {
5232 		pr_err("Preemption disabled at:");
5233 		print_ip_sym(KERN_ERR, preempt_disable_ip);
5234 	}
5235 	if (panic_on_warn)
5236 		panic("scheduling while atomic\n");
5237 
5238 	dump_stack();
5239 	add_taint(TAINT_WARN, LOCKDEP_STILL_OK);
5240 }
5241 
5242 /*
5243  * Various schedule()-time debugging checks and statistics:
5244  */
5245 static inline void schedule_debug(struct task_struct *prev, bool preempt)
5246 {
5247 #ifdef CONFIG_SCHED_STACK_END_CHECK
5248 	if (task_stack_end_corrupted(prev))
5249 		panic("corrupted stack end detected inside scheduler\n");
5250 
5251 	if (task_scs_end_corrupted(prev))
5252 		panic("corrupted shadow stack detected inside scheduler\n");
5253 #endif
5254 
5255 #ifdef CONFIG_DEBUG_ATOMIC_SLEEP
5256 	if (!preempt && READ_ONCE(prev->__state) && prev->non_block_count) {
5257 		printk(KERN_ERR "BUG: scheduling in a non-blocking section: %s/%d/%i\n",
5258 			prev->comm, prev->pid, prev->non_block_count);
5259 		dump_stack();
5260 		add_taint(TAINT_WARN, LOCKDEP_STILL_OK);
5261 	}
5262 #endif
5263 
5264 	if (unlikely(in_atomic_preempt_off())) {
5265 		__schedule_bug(prev);
5266 		preempt_count_set(PREEMPT_DISABLED);
5267 	}
5268 	rcu_sleep_check();
5269 	SCHED_WARN_ON(ct_state() == CONTEXT_USER);
5270 
5271 	profile_hit(SCHED_PROFILING, __builtin_return_address(0));
5272 
5273 	schedstat_inc(this_rq()->sched_count);
5274 }
5275 
5276 static void put_prev_task_balance(struct rq *rq, struct task_struct *prev,
5277 				  struct rq_flags *rf)
5278 {
5279 #ifdef CONFIG_SMP
5280 	const struct sched_class *class;
5281 	/*
5282 	 * We must do the balancing pass before put_prev_task(), such
5283 	 * that when we release the rq->lock the task is in the same
5284 	 * state as before we took rq->lock.
5285 	 *
5286 	 * We can terminate the balance pass as soon as we know there is
5287 	 * a runnable task of @class priority or higher.
5288 	 */
5289 	for_class_range(class, prev->sched_class, &idle_sched_class) {
5290 		if (class->balance(rq, prev, rf))
5291 			break;
5292 	}
5293 #endif
5294 
5295 	put_prev_task(rq, prev);
5296 }
5297 
5298 /*
5299  * Pick up the highest-prio task:
5300  */
5301 static inline struct task_struct *
5302 __pick_next_task(struct rq *rq, struct task_struct *prev, struct rq_flags *rf)
5303 {
5304 	const struct sched_class *class;
5305 	struct task_struct *p;
5306 
5307 	/*
5308 	 * Optimization: we know that if all tasks are in the fair class we can
5309 	 * call that function directly, but only if the @prev task wasn't of a
5310 	 * higher scheduling class, because otherwise those lose the
5311 	 * opportunity to pull in more work from other CPUs.
5312 	 */
5313 	if (likely(prev->sched_class <= &fair_sched_class &&
5314 		   rq->nr_running == rq->cfs.h_nr_running)) {
5315 
5316 		p = pick_next_task_fair(rq, prev, rf);
5317 		if (unlikely(p == RETRY_TASK))
5318 			goto restart;
5319 
5320 		/* Assume the next prioritized class is idle_sched_class */
5321 		if (!p) {
5322 			put_prev_task(rq, prev);
5323 			p = pick_next_task_idle(rq);
5324 		}
5325 
5326 		return p;
5327 	}
5328 
5329 restart:
5330 	put_prev_task_balance(rq, prev, rf);
5331 
5332 	for_each_class(class) {
5333 		p = class->pick_next_task(rq);
5334 		if (p)
5335 			return p;
5336 	}
5337 
5338 	/* The idle class should always have a runnable task: */
5339 	BUG();
5340 }
5341 
5342 #ifdef CONFIG_SCHED_CORE
5343 static inline bool is_task_rq_idle(struct task_struct *t)
5344 {
5345 	return (task_rq(t)->idle == t);
5346 }
5347 
5348 static inline bool cookie_equals(struct task_struct *a, unsigned long cookie)
5349 {
5350 	return is_task_rq_idle(a) || (a->core_cookie == cookie);
5351 }
5352 
5353 static inline bool cookie_match(struct task_struct *a, struct task_struct *b)
5354 {
5355 	if (is_task_rq_idle(a) || is_task_rq_idle(b))
5356 		return true;
5357 
5358 	return a->core_cookie == b->core_cookie;
5359 }
5360 
5361 // XXX fairness/fwd progress conditions
5362 /*
5363  * Returns
5364  * - NULL if there is no runnable task for this class.
5365  * - the highest priority task for this runqueue if it matches
5366  *   rq->core->core_cookie or its priority is greater than max.
5367  * - Else returns idle_task.
5368  */
5369 static struct task_struct *
5370 pick_task(struct rq *rq, const struct sched_class *class, struct task_struct *max, bool in_fi)
5371 {
5372 	struct task_struct *class_pick, *cookie_pick;
5373 	unsigned long cookie = rq->core->core_cookie;
5374 
5375 	class_pick = class->pick_task(rq);
5376 	if (!class_pick)
5377 		return NULL;
5378 
5379 	if (!cookie) {
5380 		/*
5381 		 * If class_pick is tagged, return it only if it has
5382 		 * higher priority than max.
5383 		 */
5384 		if (max && class_pick->core_cookie &&
5385 		    prio_less(class_pick, max, in_fi))
5386 			return idle_sched_class.pick_task(rq);
5387 
5388 		return class_pick;
5389 	}
5390 
5391 	/*
5392 	 * If class_pick is idle or matches cookie, return early.
5393 	 */
5394 	if (cookie_equals(class_pick, cookie))
5395 		return class_pick;
5396 
5397 	cookie_pick = sched_core_find(rq, cookie);
5398 
5399 	/*
5400 	 * If class > max && class > cookie, it is the highest priority task on
5401 	 * the core (so far) and it must be selected, otherwise we must go with
5402 	 * the cookie pick in order to satisfy the constraint.
5403 	 */
5404 	if (prio_less(cookie_pick, class_pick, in_fi) &&
5405 	    (!max || prio_less(max, class_pick, in_fi)))
5406 		return class_pick;
5407 
5408 	return cookie_pick;
5409 }
5410 
5411 extern void task_vruntime_update(struct rq *rq, struct task_struct *p, bool in_fi);
5412 
5413 static struct task_struct *
5414 pick_next_task(struct rq *rq, struct task_struct *prev, struct rq_flags *rf)
5415 {
5416 	struct task_struct *next, *max = NULL;
5417 	const struct sched_class *class;
5418 	const struct cpumask *smt_mask;
5419 	bool fi_before = false;
5420 	int i, j, cpu, occ = 0;
5421 	bool need_sync;
5422 
5423 	if (!sched_core_enabled(rq))
5424 		return __pick_next_task(rq, prev, rf);
5425 
5426 	cpu = cpu_of(rq);
5427 
5428 	/* Stopper task is switching into idle, no need core-wide selection. */
5429 	if (cpu_is_offline(cpu)) {
5430 		/*
5431 		 * Reset core_pick so that we don't enter the fastpath when
5432 		 * coming online. core_pick would already be migrated to
5433 		 * another cpu during offline.
5434 		 */
5435 		rq->core_pick = NULL;
5436 		return __pick_next_task(rq, prev, rf);
5437 	}
5438 
5439 	/*
5440 	 * If there were no {en,de}queues since we picked (IOW, the task
5441 	 * pointers are all still valid), and we haven't scheduled the last
5442 	 * pick yet, do so now.
5443 	 *
5444 	 * rq->core_pick can be NULL if no selection was made for a CPU because
5445 	 * it was either offline or went offline during a sibling's core-wide
5446 	 * selection. In this case, do a core-wide selection.
5447 	 */
5448 	if (rq->core->core_pick_seq == rq->core->core_task_seq &&
5449 	    rq->core->core_pick_seq != rq->core_sched_seq &&
5450 	    rq->core_pick) {
5451 		WRITE_ONCE(rq->core_sched_seq, rq->core->core_pick_seq);
5452 
5453 		next = rq->core_pick;
5454 		if (next != prev) {
5455 			put_prev_task(rq, prev);
5456 			set_next_task(rq, next);
5457 		}
5458 
5459 		rq->core_pick = NULL;
5460 		return next;
5461 	}
5462 
5463 	put_prev_task_balance(rq, prev, rf);
5464 
5465 	smt_mask = cpu_smt_mask(cpu);
5466 	need_sync = !!rq->core->core_cookie;
5467 
5468 	/* reset state */
5469 	rq->core->core_cookie = 0UL;
5470 	if (rq->core->core_forceidle) {
5471 		need_sync = true;
5472 		fi_before = true;
5473 		rq->core->core_forceidle = false;
5474 	}
5475 
5476 	/*
5477 	 * core->core_task_seq, core->core_pick_seq, rq->core_sched_seq
5478 	 *
5479 	 * @task_seq guards the task state ({en,de}queues)
5480 	 * @pick_seq is the @task_seq we did a selection on
5481 	 * @sched_seq is the @pick_seq we scheduled
5482 	 *
5483 	 * However, preemptions can cause multiple picks on the same task set.
5484 	 * 'Fix' this by also increasing @task_seq for every pick.
5485 	 */
5486 	rq->core->core_task_seq++;
5487 
5488 	/*
5489 	 * Optimize for common case where this CPU has no cookies
5490 	 * and there are no cookied tasks running on siblings.
5491 	 */
5492 	if (!need_sync) {
5493 		for_each_class(class) {
5494 			next = class->pick_task(rq);
5495 			if (next)
5496 				break;
5497 		}
5498 
5499 		if (!next->core_cookie) {
5500 			rq->core_pick = NULL;
5501 			/*
5502 			 * For robustness, update the min_vruntime_fi for
5503 			 * unconstrained picks as well.
5504 			 */
5505 			WARN_ON_ONCE(fi_before);
5506 			task_vruntime_update(rq, next, false);
5507 			goto done;
5508 		}
5509 	}
5510 
5511 	for_each_cpu(i, smt_mask) {
5512 		struct rq *rq_i = cpu_rq(i);
5513 
5514 		rq_i->core_pick = NULL;
5515 
5516 		if (i != cpu)
5517 			update_rq_clock(rq_i);
5518 	}
5519 
5520 	/*
5521 	 * Try and select tasks for each sibling in descending sched_class
5522 	 * order.
5523 	 */
5524 	for_each_class(class) {
5525 again:
5526 		for_each_cpu_wrap(i, smt_mask, cpu) {
5527 			struct rq *rq_i = cpu_rq(i);
5528 			struct task_struct *p;
5529 
5530 			if (rq_i->core_pick)
5531 				continue;
5532 
5533 			/*
5534 			 * If this sibling doesn't yet have a suitable task to
5535 			 * run; ask for the most eligible task, given the
5536 			 * highest priority task already selected for this
5537 			 * core.
5538 			 */
5539 			p = pick_task(rq_i, class, max, fi_before);
5540 			if (!p)
5541 				continue;
5542 
5543 			if (!is_task_rq_idle(p))
5544 				occ++;
5545 
5546 			rq_i->core_pick = p;
5547 			if (rq_i->idle == p && rq_i->nr_running) {
5548 				rq->core->core_forceidle = true;
5549 				if (!fi_before)
5550 					rq->core->core_forceidle_seq++;
5551 			}
5552 
5553 			/*
5554 			 * If this new candidate is of higher priority than the
5555 			 * previous; and they're incompatible; we need to wipe
5556 			 * the slate and start over. pick_task makes sure that
5557 			 * p's priority is more than max if it doesn't match
5558 			 * max's cookie.
5559 			 *
5560 			 * NOTE: this is a linear max-filter and is thus bounded
5561 			 * in execution time.
5562 			 */
5563 			if (!max || !cookie_match(max, p)) {
5564 				struct task_struct *old_max = max;
5565 
5566 				rq->core->core_cookie = p->core_cookie;
5567 				max = p;
5568 
5569 				if (old_max) {
5570 					rq->core->core_forceidle = false;
5571 					for_each_cpu(j, smt_mask) {
5572 						if (j == i)
5573 							continue;
5574 
5575 						cpu_rq(j)->core_pick = NULL;
5576 					}
5577 					occ = 1;
5578 					goto again;
5579 				}
5580 			}
5581 		}
5582 	}
5583 
5584 	rq->core->core_pick_seq = rq->core->core_task_seq;
5585 	next = rq->core_pick;
5586 	rq->core_sched_seq = rq->core->core_pick_seq;
5587 
5588 	/* Something should have been selected for current CPU */
5589 	WARN_ON_ONCE(!next);
5590 
5591 	/*
5592 	 * Reschedule siblings
5593 	 *
5594 	 * NOTE: L1TF -- at this point we're no longer running the old task and
5595 	 * sending an IPI (below) ensures the sibling will no longer be running
5596 	 * their task. This ensures there is no inter-sibling overlap between
5597 	 * non-matching user state.
5598 	 */
5599 	for_each_cpu(i, smt_mask) {
5600 		struct rq *rq_i = cpu_rq(i);
5601 
5602 		/*
5603 		 * An online sibling might have gone offline before a task
5604 		 * could be picked for it, or it might be offline but later
5605 		 * happen to come online, but its too late and nothing was
5606 		 * picked for it.  That's Ok - it will pick tasks for itself,
5607 		 * so ignore it.
5608 		 */
5609 		if (!rq_i->core_pick)
5610 			continue;
5611 
5612 		/*
5613 		 * Update for new !FI->FI transitions, or if continuing to be in !FI:
5614 		 * fi_before     fi      update?
5615 		 *  0            0       1
5616 		 *  0            1       1
5617 		 *  1            0       1
5618 		 *  1            1       0
5619 		 */
5620 		if (!(fi_before && rq->core->core_forceidle))
5621 			task_vruntime_update(rq_i, rq_i->core_pick, rq->core->core_forceidle);
5622 
5623 		rq_i->core_pick->core_occupation = occ;
5624 
5625 		if (i == cpu) {
5626 			rq_i->core_pick = NULL;
5627 			continue;
5628 		}
5629 
5630 		/* Did we break L1TF mitigation requirements? */
5631 		WARN_ON_ONCE(!cookie_match(next, rq_i->core_pick));
5632 
5633 		if (rq_i->curr == rq_i->core_pick) {
5634 			rq_i->core_pick = NULL;
5635 			continue;
5636 		}
5637 
5638 		resched_curr(rq_i);
5639 	}
5640 
5641 done:
5642 	set_next_task(rq, next);
5643 	return next;
5644 }
5645 
5646 static bool try_steal_cookie(int this, int that)
5647 {
5648 	struct rq *dst = cpu_rq(this), *src = cpu_rq(that);
5649 	struct task_struct *p;
5650 	unsigned long cookie;
5651 	bool success = false;
5652 
5653 	local_irq_disable();
5654 	double_rq_lock(dst, src);
5655 
5656 	cookie = dst->core->core_cookie;
5657 	if (!cookie)
5658 		goto unlock;
5659 
5660 	if (dst->curr != dst->idle)
5661 		goto unlock;
5662 
5663 	p = sched_core_find(src, cookie);
5664 	if (p == src->idle)
5665 		goto unlock;
5666 
5667 	do {
5668 		if (p == src->core_pick || p == src->curr)
5669 			goto next;
5670 
5671 		if (!cpumask_test_cpu(this, &p->cpus_mask))
5672 			goto next;
5673 
5674 		if (p->core_occupation > dst->idle->core_occupation)
5675 			goto next;
5676 
5677 		p->on_rq = TASK_ON_RQ_MIGRATING;
5678 		deactivate_task(src, p, 0);
5679 		set_task_cpu(p, this);
5680 		activate_task(dst, p, 0);
5681 		p->on_rq = TASK_ON_RQ_QUEUED;
5682 
5683 		resched_curr(dst);
5684 
5685 		success = true;
5686 		break;
5687 
5688 next:
5689 		p = sched_core_next(p, cookie);
5690 	} while (p);
5691 
5692 unlock:
5693 	double_rq_unlock(dst, src);
5694 	local_irq_enable();
5695 
5696 	return success;
5697 }
5698 
5699 static bool steal_cookie_task(int cpu, struct sched_domain *sd)
5700 {
5701 	int i;
5702 
5703 	for_each_cpu_wrap(i, sched_domain_span(sd), cpu) {
5704 		if (i == cpu)
5705 			continue;
5706 
5707 		if (need_resched())
5708 			break;
5709 
5710 		if (try_steal_cookie(cpu, i))
5711 			return true;
5712 	}
5713 
5714 	return false;
5715 }
5716 
5717 static void sched_core_balance(struct rq *rq)
5718 {
5719 	struct sched_domain *sd;
5720 	int cpu = cpu_of(rq);
5721 
5722 	preempt_disable();
5723 	rcu_read_lock();
5724 	raw_spin_rq_unlock_irq(rq);
5725 	for_each_domain(cpu, sd) {
5726 		if (need_resched())
5727 			break;
5728 
5729 		if (steal_cookie_task(cpu, sd))
5730 			break;
5731 	}
5732 	raw_spin_rq_lock_irq(rq);
5733 	rcu_read_unlock();
5734 	preempt_enable();
5735 }
5736 
5737 static DEFINE_PER_CPU(struct callback_head, core_balance_head);
5738 
5739 void queue_core_balance(struct rq *rq)
5740 {
5741 	if (!sched_core_enabled(rq))
5742 		return;
5743 
5744 	if (!rq->core->core_cookie)
5745 		return;
5746 
5747 	if (!rq->nr_running) /* not forced idle */
5748 		return;
5749 
5750 	queue_balance_callback(rq, &per_cpu(core_balance_head, rq->cpu), sched_core_balance);
5751 }
5752 
5753 static void sched_core_cpu_starting(unsigned int cpu)
5754 {
5755 	const struct cpumask *smt_mask = cpu_smt_mask(cpu);
5756 	struct rq *rq = cpu_rq(cpu), *core_rq = NULL;
5757 	unsigned long flags;
5758 	int t;
5759 
5760 	sched_core_lock(cpu, &flags);
5761 
5762 	WARN_ON_ONCE(rq->core != rq);
5763 
5764 	/* if we're the first, we'll be our own leader */
5765 	if (cpumask_weight(smt_mask) == 1)
5766 		goto unlock;
5767 
5768 	/* find the leader */
5769 	for_each_cpu(t, smt_mask) {
5770 		if (t == cpu)
5771 			continue;
5772 		rq = cpu_rq(t);
5773 		if (rq->core == rq) {
5774 			core_rq = rq;
5775 			break;
5776 		}
5777 	}
5778 
5779 	if (WARN_ON_ONCE(!core_rq)) /* whoopsie */
5780 		goto unlock;
5781 
5782 	/* install and validate core_rq */
5783 	for_each_cpu(t, smt_mask) {
5784 		rq = cpu_rq(t);
5785 
5786 		if (t == cpu)
5787 			rq->core = core_rq;
5788 
5789 		WARN_ON_ONCE(rq->core != core_rq);
5790 	}
5791 
5792 unlock:
5793 	sched_core_unlock(cpu, &flags);
5794 }
5795 
5796 static void sched_core_cpu_deactivate(unsigned int cpu)
5797 {
5798 	const struct cpumask *smt_mask = cpu_smt_mask(cpu);
5799 	struct rq *rq = cpu_rq(cpu), *core_rq = NULL;
5800 	unsigned long flags;
5801 	int t;
5802 
5803 	sched_core_lock(cpu, &flags);
5804 
5805 	/* if we're the last man standing, nothing to do */
5806 	if (cpumask_weight(smt_mask) == 1) {
5807 		WARN_ON_ONCE(rq->core != rq);
5808 		goto unlock;
5809 	}
5810 
5811 	/* if we're not the leader, nothing to do */
5812 	if (rq->core != rq)
5813 		goto unlock;
5814 
5815 	/* find a new leader */
5816 	for_each_cpu(t, smt_mask) {
5817 		if (t == cpu)
5818 			continue;
5819 		core_rq = cpu_rq(t);
5820 		break;
5821 	}
5822 
5823 	if (WARN_ON_ONCE(!core_rq)) /* impossible */
5824 		goto unlock;
5825 
5826 	/* copy the shared state to the new leader */
5827 	core_rq->core_task_seq      = rq->core_task_seq;
5828 	core_rq->core_pick_seq      = rq->core_pick_seq;
5829 	core_rq->core_cookie        = rq->core_cookie;
5830 	core_rq->core_forceidle     = rq->core_forceidle;
5831 	core_rq->core_forceidle_seq = rq->core_forceidle_seq;
5832 
5833 	/* install new leader */
5834 	for_each_cpu(t, smt_mask) {
5835 		rq = cpu_rq(t);
5836 		rq->core = core_rq;
5837 	}
5838 
5839 unlock:
5840 	sched_core_unlock(cpu, &flags);
5841 }
5842 
5843 static inline void sched_core_cpu_dying(unsigned int cpu)
5844 {
5845 	struct rq *rq = cpu_rq(cpu);
5846 
5847 	if (rq->core != rq)
5848 		rq->core = rq;
5849 }
5850 
5851 #else /* !CONFIG_SCHED_CORE */
5852 
5853 static inline void sched_core_cpu_starting(unsigned int cpu) {}
5854 static inline void sched_core_cpu_deactivate(unsigned int cpu) {}
5855 static inline void sched_core_cpu_dying(unsigned int cpu) {}
5856 
5857 static struct task_struct *
5858 pick_next_task(struct rq *rq, struct task_struct *prev, struct rq_flags *rf)
5859 {
5860 	return __pick_next_task(rq, prev, rf);
5861 }
5862 
5863 #endif /* CONFIG_SCHED_CORE */
5864 
5865 /*
5866  * __schedule() is the main scheduler function.
5867  *
5868  * The main means of driving the scheduler and thus entering this function are:
5869  *
5870  *   1. Explicit blocking: mutex, semaphore, waitqueue, etc.
5871  *
5872  *   2. TIF_NEED_RESCHED flag is checked on interrupt and userspace return
5873  *      paths. For example, see arch/x86/entry_64.S.
5874  *
5875  *      To drive preemption between tasks, the scheduler sets the flag in timer
5876  *      interrupt handler scheduler_tick().
5877  *
5878  *   3. Wakeups don't really cause entry into schedule(). They add a
5879  *      task to the run-queue and that's it.
5880  *
5881  *      Now, if the new task added to the run-queue preempts the current
5882  *      task, then the wakeup sets TIF_NEED_RESCHED and schedule() gets
5883  *      called on the nearest possible occasion:
5884  *
5885  *       - If the kernel is preemptible (CONFIG_PREEMPTION=y):
5886  *
5887  *         - in syscall or exception context, at the next outmost
5888  *           preempt_enable(). (this might be as soon as the wake_up()'s
5889  *           spin_unlock()!)
5890  *
5891  *         - in IRQ context, return from interrupt-handler to
5892  *           preemptible context
5893  *
5894  *       - If the kernel is not preemptible (CONFIG_PREEMPTION is not set)
5895  *         then at the next:
5896  *
5897  *          - cond_resched() call
5898  *          - explicit schedule() call
5899  *          - return from syscall or exception to user-space
5900  *          - return from interrupt-handler to user-space
5901  *
5902  * WARNING: must be called with preemption disabled!
5903  */
5904 static void __sched notrace __schedule(bool preempt)
5905 {
5906 	struct task_struct *prev, *next;
5907 	unsigned long *switch_count;
5908 	unsigned long prev_state;
5909 	struct rq_flags rf;
5910 	struct rq *rq;
5911 	int cpu;
5912 
5913 	cpu = smp_processor_id();
5914 	rq = cpu_rq(cpu);
5915 	prev = rq->curr;
5916 
5917 	schedule_debug(prev, preempt);
5918 
5919 	if (sched_feat(HRTICK) || sched_feat(HRTICK_DL))
5920 		hrtick_clear(rq);
5921 
5922 	local_irq_disable();
5923 	rcu_note_context_switch(preempt);
5924 
5925 	/*
5926 	 * Make sure that signal_pending_state()->signal_pending() below
5927 	 * can't be reordered with __set_current_state(TASK_INTERRUPTIBLE)
5928 	 * done by the caller to avoid the race with signal_wake_up():
5929 	 *
5930 	 * __set_current_state(@state)		signal_wake_up()
5931 	 * schedule()				  set_tsk_thread_flag(p, TIF_SIGPENDING)
5932 	 *					  wake_up_state(p, state)
5933 	 *   LOCK rq->lock			    LOCK p->pi_state
5934 	 *   smp_mb__after_spinlock()		    smp_mb__after_spinlock()
5935 	 *     if (signal_pending_state())	    if (p->state & @state)
5936 	 *
5937 	 * Also, the membarrier system call requires a full memory barrier
5938 	 * after coming from user-space, before storing to rq->curr.
5939 	 */
5940 	rq_lock(rq, &rf);
5941 	smp_mb__after_spinlock();
5942 
5943 	/* Promote REQ to ACT */
5944 	rq->clock_update_flags <<= 1;
5945 	update_rq_clock(rq);
5946 
5947 	switch_count = &prev->nivcsw;
5948 
5949 	/*
5950 	 * We must load prev->state once (task_struct::state is volatile), such
5951 	 * that:
5952 	 *
5953 	 *  - we form a control dependency vs deactivate_task() below.
5954 	 *  - ptrace_{,un}freeze_traced() can change ->state underneath us.
5955 	 */
5956 	prev_state = READ_ONCE(prev->__state);
5957 	if (!preempt && prev_state) {
5958 		if (signal_pending_state(prev_state, prev)) {
5959 			WRITE_ONCE(prev->__state, TASK_RUNNING);
5960 		} else {
5961 			prev->sched_contributes_to_load =
5962 				(prev_state & TASK_UNINTERRUPTIBLE) &&
5963 				!(prev_state & TASK_NOLOAD) &&
5964 				!(prev->flags & PF_FROZEN);
5965 
5966 			if (prev->sched_contributes_to_load)
5967 				rq->nr_uninterruptible++;
5968 
5969 			/*
5970 			 * __schedule()			ttwu()
5971 			 *   prev_state = prev->state;    if (p->on_rq && ...)
5972 			 *   if (prev_state)		    goto out;
5973 			 *     p->on_rq = 0;		  smp_acquire__after_ctrl_dep();
5974 			 *				  p->state = TASK_WAKING
5975 			 *
5976 			 * Where __schedule() and ttwu() have matching control dependencies.
5977 			 *
5978 			 * After this, schedule() must not care about p->state any more.
5979 			 */
5980 			deactivate_task(rq, prev, DEQUEUE_SLEEP | DEQUEUE_NOCLOCK);
5981 
5982 			if (prev->in_iowait) {
5983 				atomic_inc(&rq->nr_iowait);
5984 				delayacct_blkio_start();
5985 			}
5986 		}
5987 		switch_count = &prev->nvcsw;
5988 	}
5989 
5990 	next = pick_next_task(rq, prev, &rf);
5991 	clear_tsk_need_resched(prev);
5992 	clear_preempt_need_resched();
5993 #ifdef CONFIG_SCHED_DEBUG
5994 	rq->last_seen_need_resched_ns = 0;
5995 #endif
5996 
5997 	if (likely(prev != next)) {
5998 		rq->nr_switches++;
5999 		/*
6000 		 * RCU users of rcu_dereference(rq->curr) may not see
6001 		 * changes to task_struct made by pick_next_task().
6002 		 */
6003 		RCU_INIT_POINTER(rq->curr, next);
6004 		/*
6005 		 * The membarrier system call requires each architecture
6006 		 * to have a full memory barrier after updating
6007 		 * rq->curr, before returning to user-space.
6008 		 *
6009 		 * Here are the schemes providing that barrier on the
6010 		 * various architectures:
6011 		 * - mm ? switch_mm() : mmdrop() for x86, s390, sparc, PowerPC.
6012 		 *   switch_mm() rely on membarrier_arch_switch_mm() on PowerPC.
6013 		 * - finish_lock_switch() for weakly-ordered
6014 		 *   architectures where spin_unlock is a full barrier,
6015 		 * - switch_to() for arm64 (weakly-ordered, spin_unlock
6016 		 *   is a RELEASE barrier),
6017 		 */
6018 		++*switch_count;
6019 
6020 		migrate_disable_switch(rq, prev);
6021 		psi_sched_switch(prev, next, !task_on_rq_queued(prev));
6022 
6023 		trace_sched_switch(preempt, prev, next);
6024 
6025 		/* Also unlocks the rq: */
6026 		rq = context_switch(rq, prev, next, &rf);
6027 	} else {
6028 		rq->clock_update_flags &= ~(RQCF_ACT_SKIP|RQCF_REQ_SKIP);
6029 
6030 		rq_unpin_lock(rq, &rf);
6031 		__balance_callbacks(rq);
6032 		raw_spin_rq_unlock_irq(rq);
6033 	}
6034 }
6035 
6036 void __noreturn do_task_dead(void)
6037 {
6038 	/* Causes final put_task_struct in finish_task_switch(): */
6039 	set_special_state(TASK_DEAD);
6040 
6041 	/* Tell freezer to ignore us: */
6042 	current->flags |= PF_NOFREEZE;
6043 
6044 	__schedule(false);
6045 	BUG();
6046 
6047 	/* Avoid "noreturn function does return" - but don't continue if BUG() is a NOP: */
6048 	for (;;)
6049 		cpu_relax();
6050 }
6051 
6052 static inline void sched_submit_work(struct task_struct *tsk)
6053 {
6054 	unsigned int task_flags;
6055 
6056 	if (task_is_running(tsk))
6057 		return;
6058 
6059 	task_flags = tsk->flags;
6060 	/*
6061 	 * If a worker went to sleep, notify and ask workqueue whether
6062 	 * it wants to wake up a task to maintain concurrency.
6063 	 * As this function is called inside the schedule() context,
6064 	 * we disable preemption to avoid it calling schedule() again
6065 	 * in the possible wakeup of a kworker and because wq_worker_sleeping()
6066 	 * requires it.
6067 	 */
6068 	if (task_flags & (PF_WQ_WORKER | PF_IO_WORKER)) {
6069 		preempt_disable();
6070 		if (task_flags & PF_WQ_WORKER)
6071 			wq_worker_sleeping(tsk);
6072 		else
6073 			io_wq_worker_sleeping(tsk);
6074 		preempt_enable_no_resched();
6075 	}
6076 
6077 	if (tsk_is_pi_blocked(tsk))
6078 		return;
6079 
6080 	/*
6081 	 * If we are going to sleep and we have plugged IO queued,
6082 	 * make sure to submit it to avoid deadlocks.
6083 	 */
6084 	if (blk_needs_flush_plug(tsk))
6085 		blk_schedule_flush_plug(tsk);
6086 }
6087 
6088 static void sched_update_worker(struct task_struct *tsk)
6089 {
6090 	if (tsk->flags & (PF_WQ_WORKER | PF_IO_WORKER)) {
6091 		if (tsk->flags & PF_WQ_WORKER)
6092 			wq_worker_running(tsk);
6093 		else
6094 			io_wq_worker_running(tsk);
6095 	}
6096 }
6097 
6098 asmlinkage __visible void __sched schedule(void)
6099 {
6100 	struct task_struct *tsk = current;
6101 
6102 	sched_submit_work(tsk);
6103 	do {
6104 		preempt_disable();
6105 		__schedule(false);
6106 		sched_preempt_enable_no_resched();
6107 	} while (need_resched());
6108 	sched_update_worker(tsk);
6109 }
6110 EXPORT_SYMBOL(schedule);
6111 
6112 /*
6113  * synchronize_rcu_tasks() makes sure that no task is stuck in preempted
6114  * state (have scheduled out non-voluntarily) by making sure that all
6115  * tasks have either left the run queue or have gone into user space.
6116  * As idle tasks do not do either, they must not ever be preempted
6117  * (schedule out non-voluntarily).
6118  *
6119  * schedule_idle() is similar to schedule_preempt_disable() except that it
6120  * never enables preemption because it does not call sched_submit_work().
6121  */
6122 void __sched schedule_idle(void)
6123 {
6124 	/*
6125 	 * As this skips calling sched_submit_work(), which the idle task does
6126 	 * regardless because that function is a nop when the task is in a
6127 	 * TASK_RUNNING state, make sure this isn't used someplace that the
6128 	 * current task can be in any other state. Note, idle is always in the
6129 	 * TASK_RUNNING state.
6130 	 */
6131 	WARN_ON_ONCE(current->__state);
6132 	do {
6133 		__schedule(false);
6134 	} while (need_resched());
6135 }
6136 
6137 #if defined(CONFIG_CONTEXT_TRACKING) && !defined(CONFIG_HAVE_CONTEXT_TRACKING_OFFSTACK)
6138 asmlinkage __visible void __sched schedule_user(void)
6139 {
6140 	/*
6141 	 * If we come here after a random call to set_need_resched(),
6142 	 * or we have been woken up remotely but the IPI has not yet arrived,
6143 	 * we haven't yet exited the RCU idle mode. Do it here manually until
6144 	 * we find a better solution.
6145 	 *
6146 	 * NB: There are buggy callers of this function.  Ideally we
6147 	 * should warn if prev_state != CONTEXT_USER, but that will trigger
6148 	 * too frequently to make sense yet.
6149 	 */
6150 	enum ctx_state prev_state = exception_enter();
6151 	schedule();
6152 	exception_exit(prev_state);
6153 }
6154 #endif
6155 
6156 /**
6157  * schedule_preempt_disabled - called with preemption disabled
6158  *
6159  * Returns with preemption disabled. Note: preempt_count must be 1
6160  */
6161 void __sched schedule_preempt_disabled(void)
6162 {
6163 	sched_preempt_enable_no_resched();
6164 	schedule();
6165 	preempt_disable();
6166 }
6167 
6168 static void __sched notrace preempt_schedule_common(void)
6169 {
6170 	do {
6171 		/*
6172 		 * Because the function tracer can trace preempt_count_sub()
6173 		 * and it also uses preempt_enable/disable_notrace(), if
6174 		 * NEED_RESCHED is set, the preempt_enable_notrace() called
6175 		 * by the function tracer will call this function again and
6176 		 * cause infinite recursion.
6177 		 *
6178 		 * Preemption must be disabled here before the function
6179 		 * tracer can trace. Break up preempt_disable() into two
6180 		 * calls. One to disable preemption without fear of being
6181 		 * traced. The other to still record the preemption latency,
6182 		 * which can also be traced by the function tracer.
6183 		 */
6184 		preempt_disable_notrace();
6185 		preempt_latency_start(1);
6186 		__schedule(true);
6187 		preempt_latency_stop(1);
6188 		preempt_enable_no_resched_notrace();
6189 
6190 		/*
6191 		 * Check again in case we missed a preemption opportunity
6192 		 * between schedule and now.
6193 		 */
6194 	} while (need_resched());
6195 }
6196 
6197 #ifdef CONFIG_PREEMPTION
6198 /*
6199  * This is the entry point to schedule() from in-kernel preemption
6200  * off of preempt_enable.
6201  */
6202 asmlinkage __visible void __sched notrace preempt_schedule(void)
6203 {
6204 	/*
6205 	 * If there is a non-zero preempt_count or interrupts are disabled,
6206 	 * we do not want to preempt the current task. Just return..
6207 	 */
6208 	if (likely(!preemptible()))
6209 		return;
6210 
6211 	preempt_schedule_common();
6212 }
6213 NOKPROBE_SYMBOL(preempt_schedule);
6214 EXPORT_SYMBOL(preempt_schedule);
6215 
6216 #ifdef CONFIG_PREEMPT_DYNAMIC
6217 DEFINE_STATIC_CALL(preempt_schedule, __preempt_schedule_func);
6218 EXPORT_STATIC_CALL_TRAMP(preempt_schedule);
6219 #endif
6220 
6221 
6222 /**
6223  * preempt_schedule_notrace - preempt_schedule called by tracing
6224  *
6225  * The tracing infrastructure uses preempt_enable_notrace to prevent
6226  * recursion and tracing preempt enabling caused by the tracing
6227  * infrastructure itself. But as tracing can happen in areas coming
6228  * from userspace or just about to enter userspace, a preempt enable
6229  * can occur before user_exit() is called. This will cause the scheduler
6230  * to be called when the system is still in usermode.
6231  *
6232  * To prevent this, the preempt_enable_notrace will use this function
6233  * instead of preempt_schedule() to exit user context if needed before
6234  * calling the scheduler.
6235  */
6236 asmlinkage __visible void __sched notrace preempt_schedule_notrace(void)
6237 {
6238 	enum ctx_state prev_ctx;
6239 
6240 	if (likely(!preemptible()))
6241 		return;
6242 
6243 	do {
6244 		/*
6245 		 * Because the function tracer can trace preempt_count_sub()
6246 		 * and it also uses preempt_enable/disable_notrace(), if
6247 		 * NEED_RESCHED is set, the preempt_enable_notrace() called
6248 		 * by the function tracer will call this function again and
6249 		 * cause infinite recursion.
6250 		 *
6251 		 * Preemption must be disabled here before the function
6252 		 * tracer can trace. Break up preempt_disable() into two
6253 		 * calls. One to disable preemption without fear of being
6254 		 * traced. The other to still record the preemption latency,
6255 		 * which can also be traced by the function tracer.
6256 		 */
6257 		preempt_disable_notrace();
6258 		preempt_latency_start(1);
6259 		/*
6260 		 * Needs preempt disabled in case user_exit() is traced
6261 		 * and the tracer calls preempt_enable_notrace() causing
6262 		 * an infinite recursion.
6263 		 */
6264 		prev_ctx = exception_enter();
6265 		__schedule(true);
6266 		exception_exit(prev_ctx);
6267 
6268 		preempt_latency_stop(1);
6269 		preempt_enable_no_resched_notrace();
6270 	} while (need_resched());
6271 }
6272 EXPORT_SYMBOL_GPL(preempt_schedule_notrace);
6273 
6274 #ifdef CONFIG_PREEMPT_DYNAMIC
6275 DEFINE_STATIC_CALL(preempt_schedule_notrace, __preempt_schedule_notrace_func);
6276 EXPORT_STATIC_CALL_TRAMP(preempt_schedule_notrace);
6277 #endif
6278 
6279 #endif /* CONFIG_PREEMPTION */
6280 
6281 #ifdef CONFIG_PREEMPT_DYNAMIC
6282 
6283 #include <linux/entry-common.h>
6284 
6285 /*
6286  * SC:cond_resched
6287  * SC:might_resched
6288  * SC:preempt_schedule
6289  * SC:preempt_schedule_notrace
6290  * SC:irqentry_exit_cond_resched
6291  *
6292  *
6293  * NONE:
6294  *   cond_resched               <- __cond_resched
6295  *   might_resched              <- RET0
6296  *   preempt_schedule           <- NOP
6297  *   preempt_schedule_notrace   <- NOP
6298  *   irqentry_exit_cond_resched <- NOP
6299  *
6300  * VOLUNTARY:
6301  *   cond_resched               <- __cond_resched
6302  *   might_resched              <- __cond_resched
6303  *   preempt_schedule           <- NOP
6304  *   preempt_schedule_notrace   <- NOP
6305  *   irqentry_exit_cond_resched <- NOP
6306  *
6307  * FULL:
6308  *   cond_resched               <- RET0
6309  *   might_resched              <- RET0
6310  *   preempt_schedule           <- preempt_schedule
6311  *   preempt_schedule_notrace   <- preempt_schedule_notrace
6312  *   irqentry_exit_cond_resched <- irqentry_exit_cond_resched
6313  */
6314 
6315 enum {
6316 	preempt_dynamic_none = 0,
6317 	preempt_dynamic_voluntary,
6318 	preempt_dynamic_full,
6319 };
6320 
6321 int preempt_dynamic_mode = preempt_dynamic_full;
6322 
6323 int sched_dynamic_mode(const char *str)
6324 {
6325 	if (!strcmp(str, "none"))
6326 		return preempt_dynamic_none;
6327 
6328 	if (!strcmp(str, "voluntary"))
6329 		return preempt_dynamic_voluntary;
6330 
6331 	if (!strcmp(str, "full"))
6332 		return preempt_dynamic_full;
6333 
6334 	return -EINVAL;
6335 }
6336 
6337 void sched_dynamic_update(int mode)
6338 {
6339 	/*
6340 	 * Avoid {NONE,VOLUNTARY} -> FULL transitions from ever ending up in
6341 	 * the ZERO state, which is invalid.
6342 	 */
6343 	static_call_update(cond_resched, __cond_resched);
6344 	static_call_update(might_resched, __cond_resched);
6345 	static_call_update(preempt_schedule, __preempt_schedule_func);
6346 	static_call_update(preempt_schedule_notrace, __preempt_schedule_notrace_func);
6347 	static_call_update(irqentry_exit_cond_resched, irqentry_exit_cond_resched);
6348 
6349 	switch (mode) {
6350 	case preempt_dynamic_none:
6351 		static_call_update(cond_resched, __cond_resched);
6352 		static_call_update(might_resched, (void *)&__static_call_return0);
6353 		static_call_update(preempt_schedule, NULL);
6354 		static_call_update(preempt_schedule_notrace, NULL);
6355 		static_call_update(irqentry_exit_cond_resched, NULL);
6356 		pr_info("Dynamic Preempt: none\n");
6357 		break;
6358 
6359 	case preempt_dynamic_voluntary:
6360 		static_call_update(cond_resched, __cond_resched);
6361 		static_call_update(might_resched, __cond_resched);
6362 		static_call_update(preempt_schedule, NULL);
6363 		static_call_update(preempt_schedule_notrace, NULL);
6364 		static_call_update(irqentry_exit_cond_resched, NULL);
6365 		pr_info("Dynamic Preempt: voluntary\n");
6366 		break;
6367 
6368 	case preempt_dynamic_full:
6369 		static_call_update(cond_resched, (void *)&__static_call_return0);
6370 		static_call_update(might_resched, (void *)&__static_call_return0);
6371 		static_call_update(preempt_schedule, __preempt_schedule_func);
6372 		static_call_update(preempt_schedule_notrace, __preempt_schedule_notrace_func);
6373 		static_call_update(irqentry_exit_cond_resched, irqentry_exit_cond_resched);
6374 		pr_info("Dynamic Preempt: full\n");
6375 		break;
6376 	}
6377 
6378 	preempt_dynamic_mode = mode;
6379 }
6380 
6381 static int __init setup_preempt_mode(char *str)
6382 {
6383 	int mode = sched_dynamic_mode(str);
6384 	if (mode < 0) {
6385 		pr_warn("Dynamic Preempt: unsupported mode: %s\n", str);
6386 		return 1;
6387 	}
6388 
6389 	sched_dynamic_update(mode);
6390 	return 0;
6391 }
6392 __setup("preempt=", setup_preempt_mode);
6393 
6394 #endif /* CONFIG_PREEMPT_DYNAMIC */
6395 
6396 /*
6397  * This is the entry point to schedule() from kernel preemption
6398  * off of irq context.
6399  * Note, that this is called and return with irqs disabled. This will
6400  * protect us against recursive calling from irq.
6401  */
6402 asmlinkage __visible void __sched preempt_schedule_irq(void)
6403 {
6404 	enum ctx_state prev_state;
6405 
6406 	/* Catch callers which need to be fixed */
6407 	BUG_ON(preempt_count() || !irqs_disabled());
6408 
6409 	prev_state = exception_enter();
6410 
6411 	do {
6412 		preempt_disable();
6413 		local_irq_enable();
6414 		__schedule(true);
6415 		local_irq_disable();
6416 		sched_preempt_enable_no_resched();
6417 	} while (need_resched());
6418 
6419 	exception_exit(prev_state);
6420 }
6421 
6422 int default_wake_function(wait_queue_entry_t *curr, unsigned mode, int wake_flags,
6423 			  void *key)
6424 {
6425 	WARN_ON_ONCE(IS_ENABLED(CONFIG_SCHED_DEBUG) && wake_flags & ~WF_SYNC);
6426 	return try_to_wake_up(curr->private, mode, wake_flags);
6427 }
6428 EXPORT_SYMBOL(default_wake_function);
6429 
6430 static void __setscheduler_prio(struct task_struct *p, int prio)
6431 {
6432 	if (dl_prio(prio))
6433 		p->sched_class = &dl_sched_class;
6434 	else if (rt_prio(prio))
6435 		p->sched_class = &rt_sched_class;
6436 	else
6437 		p->sched_class = &fair_sched_class;
6438 
6439 	p->prio = prio;
6440 }
6441 
6442 #ifdef CONFIG_RT_MUTEXES
6443 
6444 static inline int __rt_effective_prio(struct task_struct *pi_task, int prio)
6445 {
6446 	if (pi_task)
6447 		prio = min(prio, pi_task->prio);
6448 
6449 	return prio;
6450 }
6451 
6452 static inline int rt_effective_prio(struct task_struct *p, int prio)
6453 {
6454 	struct task_struct *pi_task = rt_mutex_get_top_task(p);
6455 
6456 	return __rt_effective_prio(pi_task, prio);
6457 }
6458 
6459 /*
6460  * rt_mutex_setprio - set the current priority of a task
6461  * @p: task to boost
6462  * @pi_task: donor task
6463  *
6464  * This function changes the 'effective' priority of a task. It does
6465  * not touch ->normal_prio like __setscheduler().
6466  *
6467  * Used by the rt_mutex code to implement priority inheritance
6468  * logic. Call site only calls if the priority of the task changed.
6469  */
6470 void rt_mutex_setprio(struct task_struct *p, struct task_struct *pi_task)
6471 {
6472 	int prio, oldprio, queued, running, queue_flag =
6473 		DEQUEUE_SAVE | DEQUEUE_MOVE | DEQUEUE_NOCLOCK;
6474 	const struct sched_class *prev_class;
6475 	struct rq_flags rf;
6476 	struct rq *rq;
6477 
6478 	/* XXX used to be waiter->prio, not waiter->task->prio */
6479 	prio = __rt_effective_prio(pi_task, p->normal_prio);
6480 
6481 	/*
6482 	 * If nothing changed; bail early.
6483 	 */
6484 	if (p->pi_top_task == pi_task && prio == p->prio && !dl_prio(prio))
6485 		return;
6486 
6487 	rq = __task_rq_lock(p, &rf);
6488 	update_rq_clock(rq);
6489 	/*
6490 	 * Set under pi_lock && rq->lock, such that the value can be used under
6491 	 * either lock.
6492 	 *
6493 	 * Note that there is loads of tricky to make this pointer cache work
6494 	 * right. rt_mutex_slowunlock()+rt_mutex_postunlock() work together to
6495 	 * ensure a task is de-boosted (pi_task is set to NULL) before the
6496 	 * task is allowed to run again (and can exit). This ensures the pointer
6497 	 * points to a blocked task -- which guarantees the task is present.
6498 	 */
6499 	p->pi_top_task = pi_task;
6500 
6501 	/*
6502 	 * For FIFO/RR we only need to set prio, if that matches we're done.
6503 	 */
6504 	if (prio == p->prio && !dl_prio(prio))
6505 		goto out_unlock;
6506 
6507 	/*
6508 	 * Idle task boosting is a nono in general. There is one
6509 	 * exception, when PREEMPT_RT and NOHZ is active:
6510 	 *
6511 	 * The idle task calls get_next_timer_interrupt() and holds
6512 	 * the timer wheel base->lock on the CPU and another CPU wants
6513 	 * to access the timer (probably to cancel it). We can safely
6514 	 * ignore the boosting request, as the idle CPU runs this code
6515 	 * with interrupts disabled and will complete the lock
6516 	 * protected section without being interrupted. So there is no
6517 	 * real need to boost.
6518 	 */
6519 	if (unlikely(p == rq->idle)) {
6520 		WARN_ON(p != rq->curr);
6521 		WARN_ON(p->pi_blocked_on);
6522 		goto out_unlock;
6523 	}
6524 
6525 	trace_sched_pi_setprio(p, pi_task);
6526 	oldprio = p->prio;
6527 
6528 	if (oldprio == prio)
6529 		queue_flag &= ~DEQUEUE_MOVE;
6530 
6531 	prev_class = p->sched_class;
6532 	queued = task_on_rq_queued(p);
6533 	running = task_current(rq, p);
6534 	if (queued)
6535 		dequeue_task(rq, p, queue_flag);
6536 	if (running)
6537 		put_prev_task(rq, p);
6538 
6539 	/*
6540 	 * Boosting condition are:
6541 	 * 1. -rt task is running and holds mutex A
6542 	 *      --> -dl task blocks on mutex A
6543 	 *
6544 	 * 2. -dl task is running and holds mutex A
6545 	 *      --> -dl task blocks on mutex A and could preempt the
6546 	 *          running task
6547 	 */
6548 	if (dl_prio(prio)) {
6549 		if (!dl_prio(p->normal_prio) ||
6550 		    (pi_task && dl_prio(pi_task->prio) &&
6551 		     dl_entity_preempt(&pi_task->dl, &p->dl))) {
6552 			p->dl.pi_se = pi_task->dl.pi_se;
6553 			queue_flag |= ENQUEUE_REPLENISH;
6554 		} else {
6555 			p->dl.pi_se = &p->dl;
6556 		}
6557 	} else if (rt_prio(prio)) {
6558 		if (dl_prio(oldprio))
6559 			p->dl.pi_se = &p->dl;
6560 		if (oldprio < prio)
6561 			queue_flag |= ENQUEUE_HEAD;
6562 	} else {
6563 		if (dl_prio(oldprio))
6564 			p->dl.pi_se = &p->dl;
6565 		if (rt_prio(oldprio))
6566 			p->rt.timeout = 0;
6567 	}
6568 
6569 	__setscheduler_prio(p, prio);
6570 
6571 	if (queued)
6572 		enqueue_task(rq, p, queue_flag);
6573 	if (running)
6574 		set_next_task(rq, p);
6575 
6576 	check_class_changed(rq, p, prev_class, oldprio);
6577 out_unlock:
6578 	/* Avoid rq from going away on us: */
6579 	preempt_disable();
6580 
6581 	rq_unpin_lock(rq, &rf);
6582 	__balance_callbacks(rq);
6583 	raw_spin_rq_unlock(rq);
6584 
6585 	preempt_enable();
6586 }
6587 #else
6588 static inline int rt_effective_prio(struct task_struct *p, int prio)
6589 {
6590 	return prio;
6591 }
6592 #endif
6593 
6594 void set_user_nice(struct task_struct *p, long nice)
6595 {
6596 	bool queued, running;
6597 	int old_prio;
6598 	struct rq_flags rf;
6599 	struct rq *rq;
6600 
6601 	if (task_nice(p) == nice || nice < MIN_NICE || nice > MAX_NICE)
6602 		return;
6603 	/*
6604 	 * We have to be careful, if called from sys_setpriority(),
6605 	 * the task might be in the middle of scheduling on another CPU.
6606 	 */
6607 	rq = task_rq_lock(p, &rf);
6608 	update_rq_clock(rq);
6609 
6610 	/*
6611 	 * The RT priorities are set via sched_setscheduler(), but we still
6612 	 * allow the 'normal' nice value to be set - but as expected
6613 	 * it won't have any effect on scheduling until the task is
6614 	 * SCHED_DEADLINE, SCHED_FIFO or SCHED_RR:
6615 	 */
6616 	if (task_has_dl_policy(p) || task_has_rt_policy(p)) {
6617 		p->static_prio = NICE_TO_PRIO(nice);
6618 		goto out_unlock;
6619 	}
6620 	queued = task_on_rq_queued(p);
6621 	running = task_current(rq, p);
6622 	if (queued)
6623 		dequeue_task(rq, p, DEQUEUE_SAVE | DEQUEUE_NOCLOCK);
6624 	if (running)
6625 		put_prev_task(rq, p);
6626 
6627 	p->static_prio = NICE_TO_PRIO(nice);
6628 	set_load_weight(p, true);
6629 	old_prio = p->prio;
6630 	p->prio = effective_prio(p);
6631 
6632 	if (queued)
6633 		enqueue_task(rq, p, ENQUEUE_RESTORE | ENQUEUE_NOCLOCK);
6634 	if (running)
6635 		set_next_task(rq, p);
6636 
6637 	/*
6638 	 * If the task increased its priority or is running and
6639 	 * lowered its priority, then reschedule its CPU:
6640 	 */
6641 	p->sched_class->prio_changed(rq, p, old_prio);
6642 
6643 out_unlock:
6644 	task_rq_unlock(rq, p, &rf);
6645 }
6646 EXPORT_SYMBOL(set_user_nice);
6647 
6648 /*
6649  * can_nice - check if a task can reduce its nice value
6650  * @p: task
6651  * @nice: nice value
6652  */
6653 int can_nice(const struct task_struct *p, const int nice)
6654 {
6655 	/* Convert nice value [19,-20] to rlimit style value [1,40]: */
6656 	int nice_rlim = nice_to_rlimit(nice);
6657 
6658 	return (nice_rlim <= task_rlimit(p, RLIMIT_NICE) ||
6659 		capable(CAP_SYS_NICE));
6660 }
6661 
6662 #ifdef __ARCH_WANT_SYS_NICE
6663 
6664 /*
6665  * sys_nice - change the priority of the current process.
6666  * @increment: priority increment
6667  *
6668  * sys_setpriority is a more generic, but much slower function that
6669  * does similar things.
6670  */
6671 SYSCALL_DEFINE1(nice, int, increment)
6672 {
6673 	long nice, retval;
6674 
6675 	/*
6676 	 * Setpriority might change our priority at the same moment.
6677 	 * We don't have to worry. Conceptually one call occurs first
6678 	 * and we have a single winner.
6679 	 */
6680 	increment = clamp(increment, -NICE_WIDTH, NICE_WIDTH);
6681 	nice = task_nice(current) + increment;
6682 
6683 	nice = clamp_val(nice, MIN_NICE, MAX_NICE);
6684 	if (increment < 0 && !can_nice(current, nice))
6685 		return -EPERM;
6686 
6687 	retval = security_task_setnice(current, nice);
6688 	if (retval)
6689 		return retval;
6690 
6691 	set_user_nice(current, nice);
6692 	return 0;
6693 }
6694 
6695 #endif
6696 
6697 /**
6698  * task_prio - return the priority value of a given task.
6699  * @p: the task in question.
6700  *
6701  * Return: The priority value as seen by users in /proc.
6702  *
6703  * sched policy         return value   kernel prio    user prio/nice
6704  *
6705  * normal, batch, idle     [0 ... 39]  [100 ... 139]          0/[-20 ... 19]
6706  * fifo, rr             [-2 ... -100]     [98 ... 0]  [1 ... 99]
6707  * deadline                     -101             -1           0
6708  */
6709 int task_prio(const struct task_struct *p)
6710 {
6711 	return p->prio - MAX_RT_PRIO;
6712 }
6713 
6714 /**
6715  * idle_cpu - is a given CPU idle currently?
6716  * @cpu: the processor in question.
6717  *
6718  * Return: 1 if the CPU is currently idle. 0 otherwise.
6719  */
6720 int idle_cpu(int cpu)
6721 {
6722 	struct rq *rq = cpu_rq(cpu);
6723 
6724 	if (rq->curr != rq->idle)
6725 		return 0;
6726 
6727 	if (rq->nr_running)
6728 		return 0;
6729 
6730 #ifdef CONFIG_SMP
6731 	if (rq->ttwu_pending)
6732 		return 0;
6733 #endif
6734 
6735 	return 1;
6736 }
6737 
6738 /**
6739  * available_idle_cpu - is a given CPU idle for enqueuing work.
6740  * @cpu: the CPU in question.
6741  *
6742  * Return: 1 if the CPU is currently idle. 0 otherwise.
6743  */
6744 int available_idle_cpu(int cpu)
6745 {
6746 	if (!idle_cpu(cpu))
6747 		return 0;
6748 
6749 	if (vcpu_is_preempted(cpu))
6750 		return 0;
6751 
6752 	return 1;
6753 }
6754 
6755 /**
6756  * idle_task - return the idle task for a given CPU.
6757  * @cpu: the processor in question.
6758  *
6759  * Return: The idle task for the CPU @cpu.
6760  */
6761 struct task_struct *idle_task(int cpu)
6762 {
6763 	return cpu_rq(cpu)->idle;
6764 }
6765 
6766 #ifdef CONFIG_SMP
6767 /*
6768  * This function computes an effective utilization for the given CPU, to be
6769  * used for frequency selection given the linear relation: f = u * f_max.
6770  *
6771  * The scheduler tracks the following metrics:
6772  *
6773  *   cpu_util_{cfs,rt,dl,irq}()
6774  *   cpu_bw_dl()
6775  *
6776  * Where the cfs,rt and dl util numbers are tracked with the same metric and
6777  * synchronized windows and are thus directly comparable.
6778  *
6779  * The cfs,rt,dl utilization are the running times measured with rq->clock_task
6780  * which excludes things like IRQ and steal-time. These latter are then accrued
6781  * in the irq utilization.
6782  *
6783  * The DL bandwidth number otoh is not a measured metric but a value computed
6784  * based on the task model parameters and gives the minimal utilization
6785  * required to meet deadlines.
6786  */
6787 unsigned long effective_cpu_util(int cpu, unsigned long util_cfs,
6788 				 unsigned long max, enum cpu_util_type type,
6789 				 struct task_struct *p)
6790 {
6791 	unsigned long dl_util, util, irq;
6792 	struct rq *rq = cpu_rq(cpu);
6793 
6794 	if (!uclamp_is_used() &&
6795 	    type == FREQUENCY_UTIL && rt_rq_is_runnable(&rq->rt)) {
6796 		return max;
6797 	}
6798 
6799 	/*
6800 	 * Early check to see if IRQ/steal time saturates the CPU, can be
6801 	 * because of inaccuracies in how we track these -- see
6802 	 * update_irq_load_avg().
6803 	 */
6804 	irq = cpu_util_irq(rq);
6805 	if (unlikely(irq >= max))
6806 		return max;
6807 
6808 	/*
6809 	 * Because the time spend on RT/DL tasks is visible as 'lost' time to
6810 	 * CFS tasks and we use the same metric to track the effective
6811 	 * utilization (PELT windows are synchronized) we can directly add them
6812 	 * to obtain the CPU's actual utilization.
6813 	 *
6814 	 * CFS and RT utilization can be boosted or capped, depending on
6815 	 * utilization clamp constraints requested by currently RUNNABLE
6816 	 * tasks.
6817 	 * When there are no CFS RUNNABLE tasks, clamps are released and
6818 	 * frequency will be gracefully reduced with the utilization decay.
6819 	 */
6820 	util = util_cfs + cpu_util_rt(rq);
6821 	if (type == FREQUENCY_UTIL)
6822 		util = uclamp_rq_util_with(rq, util, p);
6823 
6824 	dl_util = cpu_util_dl(rq);
6825 
6826 	/*
6827 	 * For frequency selection we do not make cpu_util_dl() a permanent part
6828 	 * of this sum because we want to use cpu_bw_dl() later on, but we need
6829 	 * to check if the CFS+RT+DL sum is saturated (ie. no idle time) such
6830 	 * that we select f_max when there is no idle time.
6831 	 *
6832 	 * NOTE: numerical errors or stop class might cause us to not quite hit
6833 	 * saturation when we should -- something for later.
6834 	 */
6835 	if (util + dl_util >= max)
6836 		return max;
6837 
6838 	/*
6839 	 * OTOH, for energy computation we need the estimated running time, so
6840 	 * include util_dl and ignore dl_bw.
6841 	 */
6842 	if (type == ENERGY_UTIL)
6843 		util += dl_util;
6844 
6845 	/*
6846 	 * There is still idle time; further improve the number by using the
6847 	 * irq metric. Because IRQ/steal time is hidden from the task clock we
6848 	 * need to scale the task numbers:
6849 	 *
6850 	 *              max - irq
6851 	 *   U' = irq + --------- * U
6852 	 *                 max
6853 	 */
6854 	util = scale_irq_capacity(util, irq, max);
6855 	util += irq;
6856 
6857 	/*
6858 	 * Bandwidth required by DEADLINE must always be granted while, for
6859 	 * FAIR and RT, we use blocked utilization of IDLE CPUs as a mechanism
6860 	 * to gracefully reduce the frequency when no tasks show up for longer
6861 	 * periods of time.
6862 	 *
6863 	 * Ideally we would like to set bw_dl as min/guaranteed freq and util +
6864 	 * bw_dl as requested freq. However, cpufreq is not yet ready for such
6865 	 * an interface. So, we only do the latter for now.
6866 	 */
6867 	if (type == FREQUENCY_UTIL)
6868 		util += cpu_bw_dl(rq);
6869 
6870 	return min(max, util);
6871 }
6872 
6873 unsigned long sched_cpu_util(int cpu, unsigned long max)
6874 {
6875 	return effective_cpu_util(cpu, cpu_util_cfs(cpu_rq(cpu)), max,
6876 				  ENERGY_UTIL, NULL);
6877 }
6878 #endif /* CONFIG_SMP */
6879 
6880 /**
6881  * find_process_by_pid - find a process with a matching PID value.
6882  * @pid: the pid in question.
6883  *
6884  * The task of @pid, if found. %NULL otherwise.
6885  */
6886 static struct task_struct *find_process_by_pid(pid_t pid)
6887 {
6888 	return pid ? find_task_by_vpid(pid) : current;
6889 }
6890 
6891 /*
6892  * sched_setparam() passes in -1 for its policy, to let the functions
6893  * it calls know not to change it.
6894  */
6895 #define SETPARAM_POLICY	-1
6896 
6897 static void __setscheduler_params(struct task_struct *p,
6898 		const struct sched_attr *attr)
6899 {
6900 	int policy = attr->sched_policy;
6901 
6902 	if (policy == SETPARAM_POLICY)
6903 		policy = p->policy;
6904 
6905 	p->policy = policy;
6906 
6907 	if (dl_policy(policy))
6908 		__setparam_dl(p, attr);
6909 	else if (fair_policy(policy))
6910 		p->static_prio = NICE_TO_PRIO(attr->sched_nice);
6911 
6912 	/*
6913 	 * __sched_setscheduler() ensures attr->sched_priority == 0 when
6914 	 * !rt_policy. Always setting this ensures that things like
6915 	 * getparam()/getattr() don't report silly values for !rt tasks.
6916 	 */
6917 	p->rt_priority = attr->sched_priority;
6918 	p->normal_prio = normal_prio(p);
6919 	set_load_weight(p, true);
6920 }
6921 
6922 /*
6923  * Check the target process has a UID that matches the current process's:
6924  */
6925 static bool check_same_owner(struct task_struct *p)
6926 {
6927 	const struct cred *cred = current_cred(), *pcred;
6928 	bool match;
6929 
6930 	rcu_read_lock();
6931 	pcred = __task_cred(p);
6932 	match = (uid_eq(cred->euid, pcred->euid) ||
6933 		 uid_eq(cred->euid, pcred->uid));
6934 	rcu_read_unlock();
6935 	return match;
6936 }
6937 
6938 static int __sched_setscheduler(struct task_struct *p,
6939 				const struct sched_attr *attr,
6940 				bool user, bool pi)
6941 {
6942 	int oldpolicy = -1, policy = attr->sched_policy;
6943 	int retval, oldprio, newprio, queued, running;
6944 	const struct sched_class *prev_class;
6945 	struct callback_head *head;
6946 	struct rq_flags rf;
6947 	int reset_on_fork;
6948 	int queue_flags = DEQUEUE_SAVE | DEQUEUE_MOVE | DEQUEUE_NOCLOCK;
6949 	struct rq *rq;
6950 
6951 	/* The pi code expects interrupts enabled */
6952 	BUG_ON(pi && in_interrupt());
6953 recheck:
6954 	/* Double check policy once rq lock held: */
6955 	if (policy < 0) {
6956 		reset_on_fork = p->sched_reset_on_fork;
6957 		policy = oldpolicy = p->policy;
6958 	} else {
6959 		reset_on_fork = !!(attr->sched_flags & SCHED_FLAG_RESET_ON_FORK);
6960 
6961 		if (!valid_policy(policy))
6962 			return -EINVAL;
6963 	}
6964 
6965 	if (attr->sched_flags & ~(SCHED_FLAG_ALL | SCHED_FLAG_SUGOV))
6966 		return -EINVAL;
6967 
6968 	/*
6969 	 * Valid priorities for SCHED_FIFO and SCHED_RR are
6970 	 * 1..MAX_RT_PRIO-1, valid priority for SCHED_NORMAL,
6971 	 * SCHED_BATCH and SCHED_IDLE is 0.
6972 	 */
6973 	if (attr->sched_priority > MAX_RT_PRIO-1)
6974 		return -EINVAL;
6975 	if ((dl_policy(policy) && !__checkparam_dl(attr)) ||
6976 	    (rt_policy(policy) != (attr->sched_priority != 0)))
6977 		return -EINVAL;
6978 
6979 	/*
6980 	 * Allow unprivileged RT tasks to decrease priority:
6981 	 */
6982 	if (user && !capable(CAP_SYS_NICE)) {
6983 		if (fair_policy(policy)) {
6984 			if (attr->sched_nice < task_nice(p) &&
6985 			    !can_nice(p, attr->sched_nice))
6986 				return -EPERM;
6987 		}
6988 
6989 		if (rt_policy(policy)) {
6990 			unsigned long rlim_rtprio =
6991 					task_rlimit(p, RLIMIT_RTPRIO);
6992 
6993 			/* Can't set/change the rt policy: */
6994 			if (policy != p->policy && !rlim_rtprio)
6995 				return -EPERM;
6996 
6997 			/* Can't increase priority: */
6998 			if (attr->sched_priority > p->rt_priority &&
6999 			    attr->sched_priority > rlim_rtprio)
7000 				return -EPERM;
7001 		}
7002 
7003 		 /*
7004 		  * Can't set/change SCHED_DEADLINE policy at all for now
7005 		  * (safest behavior); in the future we would like to allow
7006 		  * unprivileged DL tasks to increase their relative deadline
7007 		  * or reduce their runtime (both ways reducing utilization)
7008 		  */
7009 		if (dl_policy(policy))
7010 			return -EPERM;
7011 
7012 		/*
7013 		 * Treat SCHED_IDLE as nice 20. Only allow a switch to
7014 		 * SCHED_NORMAL if the RLIMIT_NICE would normally permit it.
7015 		 */
7016 		if (task_has_idle_policy(p) && !idle_policy(policy)) {
7017 			if (!can_nice(p, task_nice(p)))
7018 				return -EPERM;
7019 		}
7020 
7021 		/* Can't change other user's priorities: */
7022 		if (!check_same_owner(p))
7023 			return -EPERM;
7024 
7025 		/* Normal users shall not reset the sched_reset_on_fork flag: */
7026 		if (p->sched_reset_on_fork && !reset_on_fork)
7027 			return -EPERM;
7028 	}
7029 
7030 	if (user) {
7031 		if (attr->sched_flags & SCHED_FLAG_SUGOV)
7032 			return -EINVAL;
7033 
7034 		retval = security_task_setscheduler(p);
7035 		if (retval)
7036 			return retval;
7037 	}
7038 
7039 	/* Update task specific "requested" clamps */
7040 	if (attr->sched_flags & SCHED_FLAG_UTIL_CLAMP) {
7041 		retval = uclamp_validate(p, attr);
7042 		if (retval)
7043 			return retval;
7044 	}
7045 
7046 	if (pi)
7047 		cpuset_read_lock();
7048 
7049 	/*
7050 	 * Make sure no PI-waiters arrive (or leave) while we are
7051 	 * changing the priority of the task:
7052 	 *
7053 	 * To be able to change p->policy safely, the appropriate
7054 	 * runqueue lock must be held.
7055 	 */
7056 	rq = task_rq_lock(p, &rf);
7057 	update_rq_clock(rq);
7058 
7059 	/*
7060 	 * Changing the policy of the stop threads its a very bad idea:
7061 	 */
7062 	if (p == rq->stop) {
7063 		retval = -EINVAL;
7064 		goto unlock;
7065 	}
7066 
7067 	/*
7068 	 * If not changing anything there's no need to proceed further,
7069 	 * but store a possible modification of reset_on_fork.
7070 	 */
7071 	if (unlikely(policy == p->policy)) {
7072 		if (fair_policy(policy) && attr->sched_nice != task_nice(p))
7073 			goto change;
7074 		if (rt_policy(policy) && attr->sched_priority != p->rt_priority)
7075 			goto change;
7076 		if (dl_policy(policy) && dl_param_changed(p, attr))
7077 			goto change;
7078 		if (attr->sched_flags & SCHED_FLAG_UTIL_CLAMP)
7079 			goto change;
7080 
7081 		p->sched_reset_on_fork = reset_on_fork;
7082 		retval = 0;
7083 		goto unlock;
7084 	}
7085 change:
7086 
7087 	if (user) {
7088 #ifdef CONFIG_RT_GROUP_SCHED
7089 		/*
7090 		 * Do not allow realtime tasks into groups that have no runtime
7091 		 * assigned.
7092 		 */
7093 		if (rt_bandwidth_enabled() && rt_policy(policy) &&
7094 				task_group(p)->rt_bandwidth.rt_runtime == 0 &&
7095 				!task_group_is_autogroup(task_group(p))) {
7096 			retval = -EPERM;
7097 			goto unlock;
7098 		}
7099 #endif
7100 #ifdef CONFIG_SMP
7101 		if (dl_bandwidth_enabled() && dl_policy(policy) &&
7102 				!(attr->sched_flags & SCHED_FLAG_SUGOV)) {
7103 			cpumask_t *span = rq->rd->span;
7104 
7105 			/*
7106 			 * Don't allow tasks with an affinity mask smaller than
7107 			 * the entire root_domain to become SCHED_DEADLINE. We
7108 			 * will also fail if there's no bandwidth available.
7109 			 */
7110 			if (!cpumask_subset(span, p->cpus_ptr) ||
7111 			    rq->rd->dl_bw.bw == 0) {
7112 				retval = -EPERM;
7113 				goto unlock;
7114 			}
7115 		}
7116 #endif
7117 	}
7118 
7119 	/* Re-check policy now with rq lock held: */
7120 	if (unlikely(oldpolicy != -1 && oldpolicy != p->policy)) {
7121 		policy = oldpolicy = -1;
7122 		task_rq_unlock(rq, p, &rf);
7123 		if (pi)
7124 			cpuset_read_unlock();
7125 		goto recheck;
7126 	}
7127 
7128 	/*
7129 	 * If setscheduling to SCHED_DEADLINE (or changing the parameters
7130 	 * of a SCHED_DEADLINE task) we need to check if enough bandwidth
7131 	 * is available.
7132 	 */
7133 	if ((dl_policy(policy) || dl_task(p)) && sched_dl_overflow(p, policy, attr)) {
7134 		retval = -EBUSY;
7135 		goto unlock;
7136 	}
7137 
7138 	p->sched_reset_on_fork = reset_on_fork;
7139 	oldprio = p->prio;
7140 
7141 	newprio = __normal_prio(policy, attr->sched_priority, attr->sched_nice);
7142 	if (pi) {
7143 		/*
7144 		 * Take priority boosted tasks into account. If the new
7145 		 * effective priority is unchanged, we just store the new
7146 		 * normal parameters and do not touch the scheduler class and
7147 		 * the runqueue. This will be done when the task deboost
7148 		 * itself.
7149 		 */
7150 		newprio = rt_effective_prio(p, newprio);
7151 		if (newprio == oldprio)
7152 			queue_flags &= ~DEQUEUE_MOVE;
7153 	}
7154 
7155 	queued = task_on_rq_queued(p);
7156 	running = task_current(rq, p);
7157 	if (queued)
7158 		dequeue_task(rq, p, queue_flags);
7159 	if (running)
7160 		put_prev_task(rq, p);
7161 
7162 	prev_class = p->sched_class;
7163 
7164 	if (!(attr->sched_flags & SCHED_FLAG_KEEP_PARAMS)) {
7165 		__setscheduler_params(p, attr);
7166 		__setscheduler_prio(p, newprio);
7167 	}
7168 	__setscheduler_uclamp(p, attr);
7169 
7170 	if (queued) {
7171 		/*
7172 		 * We enqueue to tail when the priority of a task is
7173 		 * increased (user space view).
7174 		 */
7175 		if (oldprio < p->prio)
7176 			queue_flags |= ENQUEUE_HEAD;
7177 
7178 		enqueue_task(rq, p, queue_flags);
7179 	}
7180 	if (running)
7181 		set_next_task(rq, p);
7182 
7183 	check_class_changed(rq, p, prev_class, oldprio);
7184 
7185 	/* Avoid rq from going away on us: */
7186 	preempt_disable();
7187 	head = splice_balance_callbacks(rq);
7188 	task_rq_unlock(rq, p, &rf);
7189 
7190 	if (pi) {
7191 		cpuset_read_unlock();
7192 		rt_mutex_adjust_pi(p);
7193 	}
7194 
7195 	/* Run balance callbacks after we've adjusted the PI chain: */
7196 	balance_callbacks(rq, head);
7197 	preempt_enable();
7198 
7199 	return 0;
7200 
7201 unlock:
7202 	task_rq_unlock(rq, p, &rf);
7203 	if (pi)
7204 		cpuset_read_unlock();
7205 	return retval;
7206 }
7207 
7208 static int _sched_setscheduler(struct task_struct *p, int policy,
7209 			       const struct sched_param *param, bool check)
7210 {
7211 	struct sched_attr attr = {
7212 		.sched_policy   = policy,
7213 		.sched_priority = param->sched_priority,
7214 		.sched_nice	= PRIO_TO_NICE(p->static_prio),
7215 	};
7216 
7217 	/* Fixup the legacy SCHED_RESET_ON_FORK hack. */
7218 	if ((policy != SETPARAM_POLICY) && (policy & SCHED_RESET_ON_FORK)) {
7219 		attr.sched_flags |= SCHED_FLAG_RESET_ON_FORK;
7220 		policy &= ~SCHED_RESET_ON_FORK;
7221 		attr.sched_policy = policy;
7222 	}
7223 
7224 	return __sched_setscheduler(p, &attr, check, true);
7225 }
7226 /**
7227  * sched_setscheduler - change the scheduling policy and/or RT priority of a thread.
7228  * @p: the task in question.
7229  * @policy: new policy.
7230  * @param: structure containing the new RT priority.
7231  *
7232  * Use sched_set_fifo(), read its comment.
7233  *
7234  * Return: 0 on success. An error code otherwise.
7235  *
7236  * NOTE that the task may be already dead.
7237  */
7238 int sched_setscheduler(struct task_struct *p, int policy,
7239 		       const struct sched_param *param)
7240 {
7241 	return _sched_setscheduler(p, policy, param, true);
7242 }
7243 
7244 int sched_setattr(struct task_struct *p, const struct sched_attr *attr)
7245 {
7246 	return __sched_setscheduler(p, attr, true, true);
7247 }
7248 
7249 int sched_setattr_nocheck(struct task_struct *p, const struct sched_attr *attr)
7250 {
7251 	return __sched_setscheduler(p, attr, false, true);
7252 }
7253 EXPORT_SYMBOL_GPL(sched_setattr_nocheck);
7254 
7255 /**
7256  * sched_setscheduler_nocheck - change the scheduling policy and/or RT priority of a thread from kernelspace.
7257  * @p: the task in question.
7258  * @policy: new policy.
7259  * @param: structure containing the new RT priority.
7260  *
7261  * Just like sched_setscheduler, only don't bother checking if the
7262  * current context has permission.  For example, this is needed in
7263  * stop_machine(): we create temporary high priority worker threads,
7264  * but our caller might not have that capability.
7265  *
7266  * Return: 0 on success. An error code otherwise.
7267  */
7268 int sched_setscheduler_nocheck(struct task_struct *p, int policy,
7269 			       const struct sched_param *param)
7270 {
7271 	return _sched_setscheduler(p, policy, param, false);
7272 }
7273 
7274 /*
7275  * SCHED_FIFO is a broken scheduler model; that is, it is fundamentally
7276  * incapable of resource management, which is the one thing an OS really should
7277  * be doing.
7278  *
7279  * This is of course the reason it is limited to privileged users only.
7280  *
7281  * Worse still; it is fundamentally impossible to compose static priority
7282  * workloads. You cannot take two correctly working static prio workloads
7283  * and smash them together and still expect them to work.
7284  *
7285  * For this reason 'all' FIFO tasks the kernel creates are basically at:
7286  *
7287  *   MAX_RT_PRIO / 2
7288  *
7289  * The administrator _MUST_ configure the system, the kernel simply doesn't
7290  * know enough information to make a sensible choice.
7291  */
7292 void sched_set_fifo(struct task_struct *p)
7293 {
7294 	struct sched_param sp = { .sched_priority = MAX_RT_PRIO / 2 };
7295 	WARN_ON_ONCE(sched_setscheduler_nocheck(p, SCHED_FIFO, &sp) != 0);
7296 }
7297 EXPORT_SYMBOL_GPL(sched_set_fifo);
7298 
7299 /*
7300  * For when you don't much care about FIFO, but want to be above SCHED_NORMAL.
7301  */
7302 void sched_set_fifo_low(struct task_struct *p)
7303 {
7304 	struct sched_param sp = { .sched_priority = 1 };
7305 	WARN_ON_ONCE(sched_setscheduler_nocheck(p, SCHED_FIFO, &sp) != 0);
7306 }
7307 EXPORT_SYMBOL_GPL(sched_set_fifo_low);
7308 
7309 void sched_set_normal(struct task_struct *p, int nice)
7310 {
7311 	struct sched_attr attr = {
7312 		.sched_policy = SCHED_NORMAL,
7313 		.sched_nice = nice,
7314 	};
7315 	WARN_ON_ONCE(sched_setattr_nocheck(p, &attr) != 0);
7316 }
7317 EXPORT_SYMBOL_GPL(sched_set_normal);
7318 
7319 static int
7320 do_sched_setscheduler(pid_t pid, int policy, struct sched_param __user *param)
7321 {
7322 	struct sched_param lparam;
7323 	struct task_struct *p;
7324 	int retval;
7325 
7326 	if (!param || pid < 0)
7327 		return -EINVAL;
7328 	if (copy_from_user(&lparam, param, sizeof(struct sched_param)))
7329 		return -EFAULT;
7330 
7331 	rcu_read_lock();
7332 	retval = -ESRCH;
7333 	p = find_process_by_pid(pid);
7334 	if (likely(p))
7335 		get_task_struct(p);
7336 	rcu_read_unlock();
7337 
7338 	if (likely(p)) {
7339 		retval = sched_setscheduler(p, policy, &lparam);
7340 		put_task_struct(p);
7341 	}
7342 
7343 	return retval;
7344 }
7345 
7346 /*
7347  * Mimics kernel/events/core.c perf_copy_attr().
7348  */
7349 static int sched_copy_attr(struct sched_attr __user *uattr, struct sched_attr *attr)
7350 {
7351 	u32 size;
7352 	int ret;
7353 
7354 	/* Zero the full structure, so that a short copy will be nice: */
7355 	memset(attr, 0, sizeof(*attr));
7356 
7357 	ret = get_user(size, &uattr->size);
7358 	if (ret)
7359 		return ret;
7360 
7361 	/* ABI compatibility quirk: */
7362 	if (!size)
7363 		size = SCHED_ATTR_SIZE_VER0;
7364 	if (size < SCHED_ATTR_SIZE_VER0 || size > PAGE_SIZE)
7365 		goto err_size;
7366 
7367 	ret = copy_struct_from_user(attr, sizeof(*attr), uattr, size);
7368 	if (ret) {
7369 		if (ret == -E2BIG)
7370 			goto err_size;
7371 		return ret;
7372 	}
7373 
7374 	if ((attr->sched_flags & SCHED_FLAG_UTIL_CLAMP) &&
7375 	    size < SCHED_ATTR_SIZE_VER1)
7376 		return -EINVAL;
7377 
7378 	/*
7379 	 * XXX: Do we want to be lenient like existing syscalls; or do we want
7380 	 * to be strict and return an error on out-of-bounds values?
7381 	 */
7382 	attr->sched_nice = clamp(attr->sched_nice, MIN_NICE, MAX_NICE);
7383 
7384 	return 0;
7385 
7386 err_size:
7387 	put_user(sizeof(*attr), &uattr->size);
7388 	return -E2BIG;
7389 }
7390 
7391 /**
7392  * sys_sched_setscheduler - set/change the scheduler policy and RT priority
7393  * @pid: the pid in question.
7394  * @policy: new policy.
7395  * @param: structure containing the new RT priority.
7396  *
7397  * Return: 0 on success. An error code otherwise.
7398  */
7399 SYSCALL_DEFINE3(sched_setscheduler, pid_t, pid, int, policy, struct sched_param __user *, param)
7400 {
7401 	if (policy < 0)
7402 		return -EINVAL;
7403 
7404 	return do_sched_setscheduler(pid, policy, param);
7405 }
7406 
7407 /**
7408  * sys_sched_setparam - set/change the RT priority of a thread
7409  * @pid: the pid in question.
7410  * @param: structure containing the new RT priority.
7411  *
7412  * Return: 0 on success. An error code otherwise.
7413  */
7414 SYSCALL_DEFINE2(sched_setparam, pid_t, pid, struct sched_param __user *, param)
7415 {
7416 	return do_sched_setscheduler(pid, SETPARAM_POLICY, param);
7417 }
7418 
7419 /**
7420  * sys_sched_setattr - same as above, but with extended sched_attr
7421  * @pid: the pid in question.
7422  * @uattr: structure containing the extended parameters.
7423  * @flags: for future extension.
7424  */
7425 SYSCALL_DEFINE3(sched_setattr, pid_t, pid, struct sched_attr __user *, uattr,
7426 			       unsigned int, flags)
7427 {
7428 	struct sched_attr attr;
7429 	struct task_struct *p;
7430 	int retval;
7431 
7432 	if (!uattr || pid < 0 || flags)
7433 		return -EINVAL;
7434 
7435 	retval = sched_copy_attr(uattr, &attr);
7436 	if (retval)
7437 		return retval;
7438 
7439 	if ((int)attr.sched_policy < 0)
7440 		return -EINVAL;
7441 	if (attr.sched_flags & SCHED_FLAG_KEEP_POLICY)
7442 		attr.sched_policy = SETPARAM_POLICY;
7443 
7444 	rcu_read_lock();
7445 	retval = -ESRCH;
7446 	p = find_process_by_pid(pid);
7447 	if (likely(p))
7448 		get_task_struct(p);
7449 	rcu_read_unlock();
7450 
7451 	if (likely(p)) {
7452 		retval = sched_setattr(p, &attr);
7453 		put_task_struct(p);
7454 	}
7455 
7456 	return retval;
7457 }
7458 
7459 /**
7460  * sys_sched_getscheduler - get the policy (scheduling class) of a thread
7461  * @pid: the pid in question.
7462  *
7463  * Return: On success, the policy of the thread. Otherwise, a negative error
7464  * code.
7465  */
7466 SYSCALL_DEFINE1(sched_getscheduler, pid_t, pid)
7467 {
7468 	struct task_struct *p;
7469 	int retval;
7470 
7471 	if (pid < 0)
7472 		return -EINVAL;
7473 
7474 	retval = -ESRCH;
7475 	rcu_read_lock();
7476 	p = find_process_by_pid(pid);
7477 	if (p) {
7478 		retval = security_task_getscheduler(p);
7479 		if (!retval)
7480 			retval = p->policy
7481 				| (p->sched_reset_on_fork ? SCHED_RESET_ON_FORK : 0);
7482 	}
7483 	rcu_read_unlock();
7484 	return retval;
7485 }
7486 
7487 /**
7488  * sys_sched_getparam - get the RT priority of a thread
7489  * @pid: the pid in question.
7490  * @param: structure containing the RT priority.
7491  *
7492  * Return: On success, 0 and the RT priority is in @param. Otherwise, an error
7493  * code.
7494  */
7495 SYSCALL_DEFINE2(sched_getparam, pid_t, pid, struct sched_param __user *, param)
7496 {
7497 	struct sched_param lp = { .sched_priority = 0 };
7498 	struct task_struct *p;
7499 	int retval;
7500 
7501 	if (!param || pid < 0)
7502 		return -EINVAL;
7503 
7504 	rcu_read_lock();
7505 	p = find_process_by_pid(pid);
7506 	retval = -ESRCH;
7507 	if (!p)
7508 		goto out_unlock;
7509 
7510 	retval = security_task_getscheduler(p);
7511 	if (retval)
7512 		goto out_unlock;
7513 
7514 	if (task_has_rt_policy(p))
7515 		lp.sched_priority = p->rt_priority;
7516 	rcu_read_unlock();
7517 
7518 	/*
7519 	 * This one might sleep, we cannot do it with a spinlock held ...
7520 	 */
7521 	retval = copy_to_user(param, &lp, sizeof(*param)) ? -EFAULT : 0;
7522 
7523 	return retval;
7524 
7525 out_unlock:
7526 	rcu_read_unlock();
7527 	return retval;
7528 }
7529 
7530 /*
7531  * Copy the kernel size attribute structure (which might be larger
7532  * than what user-space knows about) to user-space.
7533  *
7534  * Note that all cases are valid: user-space buffer can be larger or
7535  * smaller than the kernel-space buffer. The usual case is that both
7536  * have the same size.
7537  */
7538 static int
7539 sched_attr_copy_to_user(struct sched_attr __user *uattr,
7540 			struct sched_attr *kattr,
7541 			unsigned int usize)
7542 {
7543 	unsigned int ksize = sizeof(*kattr);
7544 
7545 	if (!access_ok(uattr, usize))
7546 		return -EFAULT;
7547 
7548 	/*
7549 	 * sched_getattr() ABI forwards and backwards compatibility:
7550 	 *
7551 	 * If usize == ksize then we just copy everything to user-space and all is good.
7552 	 *
7553 	 * If usize < ksize then we only copy as much as user-space has space for,
7554 	 * this keeps ABI compatibility as well. We skip the rest.
7555 	 *
7556 	 * If usize > ksize then user-space is using a newer version of the ABI,
7557 	 * which part the kernel doesn't know about. Just ignore it - tooling can
7558 	 * detect the kernel's knowledge of attributes from the attr->size value
7559 	 * which is set to ksize in this case.
7560 	 */
7561 	kattr->size = min(usize, ksize);
7562 
7563 	if (copy_to_user(uattr, kattr, kattr->size))
7564 		return -EFAULT;
7565 
7566 	return 0;
7567 }
7568 
7569 /**
7570  * sys_sched_getattr - similar to sched_getparam, but with sched_attr
7571  * @pid: the pid in question.
7572  * @uattr: structure containing the extended parameters.
7573  * @usize: sizeof(attr) for fwd/bwd comp.
7574  * @flags: for future extension.
7575  */
7576 SYSCALL_DEFINE4(sched_getattr, pid_t, pid, struct sched_attr __user *, uattr,
7577 		unsigned int, usize, unsigned int, flags)
7578 {
7579 	struct sched_attr kattr = { };
7580 	struct task_struct *p;
7581 	int retval;
7582 
7583 	if (!uattr || pid < 0 || usize > PAGE_SIZE ||
7584 	    usize < SCHED_ATTR_SIZE_VER0 || flags)
7585 		return -EINVAL;
7586 
7587 	rcu_read_lock();
7588 	p = find_process_by_pid(pid);
7589 	retval = -ESRCH;
7590 	if (!p)
7591 		goto out_unlock;
7592 
7593 	retval = security_task_getscheduler(p);
7594 	if (retval)
7595 		goto out_unlock;
7596 
7597 	kattr.sched_policy = p->policy;
7598 	if (p->sched_reset_on_fork)
7599 		kattr.sched_flags |= SCHED_FLAG_RESET_ON_FORK;
7600 	if (task_has_dl_policy(p))
7601 		__getparam_dl(p, &kattr);
7602 	else if (task_has_rt_policy(p))
7603 		kattr.sched_priority = p->rt_priority;
7604 	else
7605 		kattr.sched_nice = task_nice(p);
7606 
7607 #ifdef CONFIG_UCLAMP_TASK
7608 	/*
7609 	 * This could race with another potential updater, but this is fine
7610 	 * because it'll correctly read the old or the new value. We don't need
7611 	 * to guarantee who wins the race as long as it doesn't return garbage.
7612 	 */
7613 	kattr.sched_util_min = p->uclamp_req[UCLAMP_MIN].value;
7614 	kattr.sched_util_max = p->uclamp_req[UCLAMP_MAX].value;
7615 #endif
7616 
7617 	rcu_read_unlock();
7618 
7619 	return sched_attr_copy_to_user(uattr, &kattr, usize);
7620 
7621 out_unlock:
7622 	rcu_read_unlock();
7623 	return retval;
7624 }
7625 
7626 long sched_setaffinity(pid_t pid, const struct cpumask *in_mask)
7627 {
7628 	cpumask_var_t cpus_allowed, new_mask;
7629 	struct task_struct *p;
7630 	int retval;
7631 
7632 	rcu_read_lock();
7633 
7634 	p = find_process_by_pid(pid);
7635 	if (!p) {
7636 		rcu_read_unlock();
7637 		return -ESRCH;
7638 	}
7639 
7640 	/* Prevent p going away */
7641 	get_task_struct(p);
7642 	rcu_read_unlock();
7643 
7644 	if (p->flags & PF_NO_SETAFFINITY) {
7645 		retval = -EINVAL;
7646 		goto out_put_task;
7647 	}
7648 	if (!alloc_cpumask_var(&cpus_allowed, GFP_KERNEL)) {
7649 		retval = -ENOMEM;
7650 		goto out_put_task;
7651 	}
7652 	if (!alloc_cpumask_var(&new_mask, GFP_KERNEL)) {
7653 		retval = -ENOMEM;
7654 		goto out_free_cpus_allowed;
7655 	}
7656 	retval = -EPERM;
7657 	if (!check_same_owner(p)) {
7658 		rcu_read_lock();
7659 		if (!ns_capable(__task_cred(p)->user_ns, CAP_SYS_NICE)) {
7660 			rcu_read_unlock();
7661 			goto out_free_new_mask;
7662 		}
7663 		rcu_read_unlock();
7664 	}
7665 
7666 	retval = security_task_setscheduler(p);
7667 	if (retval)
7668 		goto out_free_new_mask;
7669 
7670 
7671 	cpuset_cpus_allowed(p, cpus_allowed);
7672 	cpumask_and(new_mask, in_mask, cpus_allowed);
7673 
7674 	/*
7675 	 * Since bandwidth control happens on root_domain basis,
7676 	 * if admission test is enabled, we only admit -deadline
7677 	 * tasks allowed to run on all the CPUs in the task's
7678 	 * root_domain.
7679 	 */
7680 #ifdef CONFIG_SMP
7681 	if (task_has_dl_policy(p) && dl_bandwidth_enabled()) {
7682 		rcu_read_lock();
7683 		if (!cpumask_subset(task_rq(p)->rd->span, new_mask)) {
7684 			retval = -EBUSY;
7685 			rcu_read_unlock();
7686 			goto out_free_new_mask;
7687 		}
7688 		rcu_read_unlock();
7689 	}
7690 #endif
7691 again:
7692 	retval = __set_cpus_allowed_ptr(p, new_mask, SCA_CHECK);
7693 
7694 	if (!retval) {
7695 		cpuset_cpus_allowed(p, cpus_allowed);
7696 		if (!cpumask_subset(new_mask, cpus_allowed)) {
7697 			/*
7698 			 * We must have raced with a concurrent cpuset
7699 			 * update. Just reset the cpus_allowed to the
7700 			 * cpuset's cpus_allowed
7701 			 */
7702 			cpumask_copy(new_mask, cpus_allowed);
7703 			goto again;
7704 		}
7705 	}
7706 out_free_new_mask:
7707 	free_cpumask_var(new_mask);
7708 out_free_cpus_allowed:
7709 	free_cpumask_var(cpus_allowed);
7710 out_put_task:
7711 	put_task_struct(p);
7712 	return retval;
7713 }
7714 
7715 static int get_user_cpu_mask(unsigned long __user *user_mask_ptr, unsigned len,
7716 			     struct cpumask *new_mask)
7717 {
7718 	if (len < cpumask_size())
7719 		cpumask_clear(new_mask);
7720 	else if (len > cpumask_size())
7721 		len = cpumask_size();
7722 
7723 	return copy_from_user(new_mask, user_mask_ptr, len) ? -EFAULT : 0;
7724 }
7725 
7726 /**
7727  * sys_sched_setaffinity - set the CPU affinity of a process
7728  * @pid: pid of the process
7729  * @len: length in bytes of the bitmask pointed to by user_mask_ptr
7730  * @user_mask_ptr: user-space pointer to the new CPU mask
7731  *
7732  * Return: 0 on success. An error code otherwise.
7733  */
7734 SYSCALL_DEFINE3(sched_setaffinity, pid_t, pid, unsigned int, len,
7735 		unsigned long __user *, user_mask_ptr)
7736 {
7737 	cpumask_var_t new_mask;
7738 	int retval;
7739 
7740 	if (!alloc_cpumask_var(&new_mask, GFP_KERNEL))
7741 		return -ENOMEM;
7742 
7743 	retval = get_user_cpu_mask(user_mask_ptr, len, new_mask);
7744 	if (retval == 0)
7745 		retval = sched_setaffinity(pid, new_mask);
7746 	free_cpumask_var(new_mask);
7747 	return retval;
7748 }
7749 
7750 long sched_getaffinity(pid_t pid, struct cpumask *mask)
7751 {
7752 	struct task_struct *p;
7753 	unsigned long flags;
7754 	int retval;
7755 
7756 	rcu_read_lock();
7757 
7758 	retval = -ESRCH;
7759 	p = find_process_by_pid(pid);
7760 	if (!p)
7761 		goto out_unlock;
7762 
7763 	retval = security_task_getscheduler(p);
7764 	if (retval)
7765 		goto out_unlock;
7766 
7767 	raw_spin_lock_irqsave(&p->pi_lock, flags);
7768 	cpumask_and(mask, &p->cpus_mask, cpu_active_mask);
7769 	raw_spin_unlock_irqrestore(&p->pi_lock, flags);
7770 
7771 out_unlock:
7772 	rcu_read_unlock();
7773 
7774 	return retval;
7775 }
7776 
7777 /**
7778  * sys_sched_getaffinity - get the CPU affinity of a process
7779  * @pid: pid of the process
7780  * @len: length in bytes of the bitmask pointed to by user_mask_ptr
7781  * @user_mask_ptr: user-space pointer to hold the current CPU mask
7782  *
7783  * Return: size of CPU mask copied to user_mask_ptr on success. An
7784  * error code otherwise.
7785  */
7786 SYSCALL_DEFINE3(sched_getaffinity, pid_t, pid, unsigned int, len,
7787 		unsigned long __user *, user_mask_ptr)
7788 {
7789 	int ret;
7790 	cpumask_var_t mask;
7791 
7792 	if ((len * BITS_PER_BYTE) < nr_cpu_ids)
7793 		return -EINVAL;
7794 	if (len & (sizeof(unsigned long)-1))
7795 		return -EINVAL;
7796 
7797 	if (!alloc_cpumask_var(&mask, GFP_KERNEL))
7798 		return -ENOMEM;
7799 
7800 	ret = sched_getaffinity(pid, mask);
7801 	if (ret == 0) {
7802 		unsigned int retlen = min(len, cpumask_size());
7803 
7804 		if (copy_to_user(user_mask_ptr, mask, retlen))
7805 			ret = -EFAULT;
7806 		else
7807 			ret = retlen;
7808 	}
7809 	free_cpumask_var(mask);
7810 
7811 	return ret;
7812 }
7813 
7814 static void do_sched_yield(void)
7815 {
7816 	struct rq_flags rf;
7817 	struct rq *rq;
7818 
7819 	rq = this_rq_lock_irq(&rf);
7820 
7821 	schedstat_inc(rq->yld_count);
7822 	current->sched_class->yield_task(rq);
7823 
7824 	preempt_disable();
7825 	rq_unlock_irq(rq, &rf);
7826 	sched_preempt_enable_no_resched();
7827 
7828 	schedule();
7829 }
7830 
7831 /**
7832  * sys_sched_yield - yield the current processor to other threads.
7833  *
7834  * This function yields the current CPU to other tasks. If there are no
7835  * other threads running on this CPU then this function will return.
7836  *
7837  * Return: 0.
7838  */
7839 SYSCALL_DEFINE0(sched_yield)
7840 {
7841 	do_sched_yield();
7842 	return 0;
7843 }
7844 
7845 #if !defined(CONFIG_PREEMPTION) || defined(CONFIG_PREEMPT_DYNAMIC)
7846 int __sched __cond_resched(void)
7847 {
7848 	if (should_resched(0)) {
7849 		preempt_schedule_common();
7850 		return 1;
7851 	}
7852 #ifndef CONFIG_PREEMPT_RCU
7853 	rcu_all_qs();
7854 #endif
7855 	return 0;
7856 }
7857 EXPORT_SYMBOL(__cond_resched);
7858 #endif
7859 
7860 #ifdef CONFIG_PREEMPT_DYNAMIC
7861 DEFINE_STATIC_CALL_RET0(cond_resched, __cond_resched);
7862 EXPORT_STATIC_CALL_TRAMP(cond_resched);
7863 
7864 DEFINE_STATIC_CALL_RET0(might_resched, __cond_resched);
7865 EXPORT_STATIC_CALL_TRAMP(might_resched);
7866 #endif
7867 
7868 /*
7869  * __cond_resched_lock() - if a reschedule is pending, drop the given lock,
7870  * call schedule, and on return reacquire the lock.
7871  *
7872  * This works OK both with and without CONFIG_PREEMPTION. We do strange low-level
7873  * operations here to prevent schedule() from being called twice (once via
7874  * spin_unlock(), once by hand).
7875  */
7876 int __cond_resched_lock(spinlock_t *lock)
7877 {
7878 	int resched = should_resched(PREEMPT_LOCK_OFFSET);
7879 	int ret = 0;
7880 
7881 	lockdep_assert_held(lock);
7882 
7883 	if (spin_needbreak(lock) || resched) {
7884 		spin_unlock(lock);
7885 		if (resched)
7886 			preempt_schedule_common();
7887 		else
7888 			cpu_relax();
7889 		ret = 1;
7890 		spin_lock(lock);
7891 	}
7892 	return ret;
7893 }
7894 EXPORT_SYMBOL(__cond_resched_lock);
7895 
7896 int __cond_resched_rwlock_read(rwlock_t *lock)
7897 {
7898 	int resched = should_resched(PREEMPT_LOCK_OFFSET);
7899 	int ret = 0;
7900 
7901 	lockdep_assert_held_read(lock);
7902 
7903 	if (rwlock_needbreak(lock) || resched) {
7904 		read_unlock(lock);
7905 		if (resched)
7906 			preempt_schedule_common();
7907 		else
7908 			cpu_relax();
7909 		ret = 1;
7910 		read_lock(lock);
7911 	}
7912 	return ret;
7913 }
7914 EXPORT_SYMBOL(__cond_resched_rwlock_read);
7915 
7916 int __cond_resched_rwlock_write(rwlock_t *lock)
7917 {
7918 	int resched = should_resched(PREEMPT_LOCK_OFFSET);
7919 	int ret = 0;
7920 
7921 	lockdep_assert_held_write(lock);
7922 
7923 	if (rwlock_needbreak(lock) || resched) {
7924 		write_unlock(lock);
7925 		if (resched)
7926 			preempt_schedule_common();
7927 		else
7928 			cpu_relax();
7929 		ret = 1;
7930 		write_lock(lock);
7931 	}
7932 	return ret;
7933 }
7934 EXPORT_SYMBOL(__cond_resched_rwlock_write);
7935 
7936 /**
7937  * yield - yield the current processor to other threads.
7938  *
7939  * Do not ever use this function, there's a 99% chance you're doing it wrong.
7940  *
7941  * The scheduler is at all times free to pick the calling task as the most
7942  * eligible task to run, if removing the yield() call from your code breaks
7943  * it, it's already broken.
7944  *
7945  * Typical broken usage is:
7946  *
7947  * while (!event)
7948  *	yield();
7949  *
7950  * where one assumes that yield() will let 'the other' process run that will
7951  * make event true. If the current task is a SCHED_FIFO task that will never
7952  * happen. Never use yield() as a progress guarantee!!
7953  *
7954  * If you want to use yield() to wait for something, use wait_event().
7955  * If you want to use yield() to be 'nice' for others, use cond_resched().
7956  * If you still want to use yield(), do not!
7957  */
7958 void __sched yield(void)
7959 {
7960 	set_current_state(TASK_RUNNING);
7961 	do_sched_yield();
7962 }
7963 EXPORT_SYMBOL(yield);
7964 
7965 /**
7966  * yield_to - yield the current processor to another thread in
7967  * your thread group, or accelerate that thread toward the
7968  * processor it's on.
7969  * @p: target task
7970  * @preempt: whether task preemption is allowed or not
7971  *
7972  * It's the caller's job to ensure that the target task struct
7973  * can't go away on us before we can do any checks.
7974  *
7975  * Return:
7976  *	true (>0) if we indeed boosted the target task.
7977  *	false (0) if we failed to boost the target.
7978  *	-ESRCH if there's no task to yield to.
7979  */
7980 int __sched yield_to(struct task_struct *p, bool preempt)
7981 {
7982 	struct task_struct *curr = current;
7983 	struct rq *rq, *p_rq;
7984 	unsigned long flags;
7985 	int yielded = 0;
7986 
7987 	local_irq_save(flags);
7988 	rq = this_rq();
7989 
7990 again:
7991 	p_rq = task_rq(p);
7992 	/*
7993 	 * If we're the only runnable task on the rq and target rq also
7994 	 * has only one task, there's absolutely no point in yielding.
7995 	 */
7996 	if (rq->nr_running == 1 && p_rq->nr_running == 1) {
7997 		yielded = -ESRCH;
7998 		goto out_irq;
7999 	}
8000 
8001 	double_rq_lock(rq, p_rq);
8002 	if (task_rq(p) != p_rq) {
8003 		double_rq_unlock(rq, p_rq);
8004 		goto again;
8005 	}
8006 
8007 	if (!curr->sched_class->yield_to_task)
8008 		goto out_unlock;
8009 
8010 	if (curr->sched_class != p->sched_class)
8011 		goto out_unlock;
8012 
8013 	if (task_running(p_rq, p) || !task_is_running(p))
8014 		goto out_unlock;
8015 
8016 	yielded = curr->sched_class->yield_to_task(rq, p);
8017 	if (yielded) {
8018 		schedstat_inc(rq->yld_count);
8019 		/*
8020 		 * Make p's CPU reschedule; pick_next_entity takes care of
8021 		 * fairness.
8022 		 */
8023 		if (preempt && rq != p_rq)
8024 			resched_curr(p_rq);
8025 	}
8026 
8027 out_unlock:
8028 	double_rq_unlock(rq, p_rq);
8029 out_irq:
8030 	local_irq_restore(flags);
8031 
8032 	if (yielded > 0)
8033 		schedule();
8034 
8035 	return yielded;
8036 }
8037 EXPORT_SYMBOL_GPL(yield_to);
8038 
8039 int io_schedule_prepare(void)
8040 {
8041 	int old_iowait = current->in_iowait;
8042 
8043 	current->in_iowait = 1;
8044 	blk_schedule_flush_plug(current);
8045 
8046 	return old_iowait;
8047 }
8048 
8049 void io_schedule_finish(int token)
8050 {
8051 	current->in_iowait = token;
8052 }
8053 
8054 /*
8055  * This task is about to go to sleep on IO. Increment rq->nr_iowait so
8056  * that process accounting knows that this is a task in IO wait state.
8057  */
8058 long __sched io_schedule_timeout(long timeout)
8059 {
8060 	int token;
8061 	long ret;
8062 
8063 	token = io_schedule_prepare();
8064 	ret = schedule_timeout(timeout);
8065 	io_schedule_finish(token);
8066 
8067 	return ret;
8068 }
8069 EXPORT_SYMBOL(io_schedule_timeout);
8070 
8071 void __sched io_schedule(void)
8072 {
8073 	int token;
8074 
8075 	token = io_schedule_prepare();
8076 	schedule();
8077 	io_schedule_finish(token);
8078 }
8079 EXPORT_SYMBOL(io_schedule);
8080 
8081 /**
8082  * sys_sched_get_priority_max - return maximum RT priority.
8083  * @policy: scheduling class.
8084  *
8085  * Return: On success, this syscall returns the maximum
8086  * rt_priority that can be used by a given scheduling class.
8087  * On failure, a negative error code is returned.
8088  */
8089 SYSCALL_DEFINE1(sched_get_priority_max, int, policy)
8090 {
8091 	int ret = -EINVAL;
8092 
8093 	switch (policy) {
8094 	case SCHED_FIFO:
8095 	case SCHED_RR:
8096 		ret = MAX_RT_PRIO-1;
8097 		break;
8098 	case SCHED_DEADLINE:
8099 	case SCHED_NORMAL:
8100 	case SCHED_BATCH:
8101 	case SCHED_IDLE:
8102 		ret = 0;
8103 		break;
8104 	}
8105 	return ret;
8106 }
8107 
8108 /**
8109  * sys_sched_get_priority_min - return minimum RT priority.
8110  * @policy: scheduling class.
8111  *
8112  * Return: On success, this syscall returns the minimum
8113  * rt_priority that can be used by a given scheduling class.
8114  * On failure, a negative error code is returned.
8115  */
8116 SYSCALL_DEFINE1(sched_get_priority_min, int, policy)
8117 {
8118 	int ret = -EINVAL;
8119 
8120 	switch (policy) {
8121 	case SCHED_FIFO:
8122 	case SCHED_RR:
8123 		ret = 1;
8124 		break;
8125 	case SCHED_DEADLINE:
8126 	case SCHED_NORMAL:
8127 	case SCHED_BATCH:
8128 	case SCHED_IDLE:
8129 		ret = 0;
8130 	}
8131 	return ret;
8132 }
8133 
8134 static int sched_rr_get_interval(pid_t pid, struct timespec64 *t)
8135 {
8136 	struct task_struct *p;
8137 	unsigned int time_slice;
8138 	struct rq_flags rf;
8139 	struct rq *rq;
8140 	int retval;
8141 
8142 	if (pid < 0)
8143 		return -EINVAL;
8144 
8145 	retval = -ESRCH;
8146 	rcu_read_lock();
8147 	p = find_process_by_pid(pid);
8148 	if (!p)
8149 		goto out_unlock;
8150 
8151 	retval = security_task_getscheduler(p);
8152 	if (retval)
8153 		goto out_unlock;
8154 
8155 	rq = task_rq_lock(p, &rf);
8156 	time_slice = 0;
8157 	if (p->sched_class->get_rr_interval)
8158 		time_slice = p->sched_class->get_rr_interval(rq, p);
8159 	task_rq_unlock(rq, p, &rf);
8160 
8161 	rcu_read_unlock();
8162 	jiffies_to_timespec64(time_slice, t);
8163 	return 0;
8164 
8165 out_unlock:
8166 	rcu_read_unlock();
8167 	return retval;
8168 }
8169 
8170 /**
8171  * sys_sched_rr_get_interval - return the default timeslice of a process.
8172  * @pid: pid of the process.
8173  * @interval: userspace pointer to the timeslice value.
8174  *
8175  * this syscall writes the default timeslice value of a given process
8176  * into the user-space timespec buffer. A value of '0' means infinity.
8177  *
8178  * Return: On success, 0 and the timeslice is in @interval. Otherwise,
8179  * an error code.
8180  */
8181 SYSCALL_DEFINE2(sched_rr_get_interval, pid_t, pid,
8182 		struct __kernel_timespec __user *, interval)
8183 {
8184 	struct timespec64 t;
8185 	int retval = sched_rr_get_interval(pid, &t);
8186 
8187 	if (retval == 0)
8188 		retval = put_timespec64(&t, interval);
8189 
8190 	return retval;
8191 }
8192 
8193 #ifdef CONFIG_COMPAT_32BIT_TIME
8194 SYSCALL_DEFINE2(sched_rr_get_interval_time32, pid_t, pid,
8195 		struct old_timespec32 __user *, interval)
8196 {
8197 	struct timespec64 t;
8198 	int retval = sched_rr_get_interval(pid, &t);
8199 
8200 	if (retval == 0)
8201 		retval = put_old_timespec32(&t, interval);
8202 	return retval;
8203 }
8204 #endif
8205 
8206 void sched_show_task(struct task_struct *p)
8207 {
8208 	unsigned long free = 0;
8209 	int ppid;
8210 
8211 	if (!try_get_task_stack(p))
8212 		return;
8213 
8214 	pr_info("task:%-15.15s state:%c", p->comm, task_state_to_char(p));
8215 
8216 	if (task_is_running(p))
8217 		pr_cont("  running task    ");
8218 #ifdef CONFIG_DEBUG_STACK_USAGE
8219 	free = stack_not_used(p);
8220 #endif
8221 	ppid = 0;
8222 	rcu_read_lock();
8223 	if (pid_alive(p))
8224 		ppid = task_pid_nr(rcu_dereference(p->real_parent));
8225 	rcu_read_unlock();
8226 	pr_cont(" stack:%5lu pid:%5d ppid:%6d flags:0x%08lx\n",
8227 		free, task_pid_nr(p), ppid,
8228 		(unsigned long)task_thread_info(p)->flags);
8229 
8230 	print_worker_info(KERN_INFO, p);
8231 	print_stop_info(KERN_INFO, p);
8232 	show_stack(p, NULL, KERN_INFO);
8233 	put_task_stack(p);
8234 }
8235 EXPORT_SYMBOL_GPL(sched_show_task);
8236 
8237 static inline bool
8238 state_filter_match(unsigned long state_filter, struct task_struct *p)
8239 {
8240 	unsigned int state = READ_ONCE(p->__state);
8241 
8242 	/* no filter, everything matches */
8243 	if (!state_filter)
8244 		return true;
8245 
8246 	/* filter, but doesn't match */
8247 	if (!(state & state_filter))
8248 		return false;
8249 
8250 	/*
8251 	 * When looking for TASK_UNINTERRUPTIBLE skip TASK_IDLE (allows
8252 	 * TASK_KILLABLE).
8253 	 */
8254 	if (state_filter == TASK_UNINTERRUPTIBLE && state == TASK_IDLE)
8255 		return false;
8256 
8257 	return true;
8258 }
8259 
8260 
8261 void show_state_filter(unsigned int state_filter)
8262 {
8263 	struct task_struct *g, *p;
8264 
8265 	rcu_read_lock();
8266 	for_each_process_thread(g, p) {
8267 		/*
8268 		 * reset the NMI-timeout, listing all files on a slow
8269 		 * console might take a lot of time:
8270 		 * Also, reset softlockup watchdogs on all CPUs, because
8271 		 * another CPU might be blocked waiting for us to process
8272 		 * an IPI.
8273 		 */
8274 		touch_nmi_watchdog();
8275 		touch_all_softlockup_watchdogs();
8276 		if (state_filter_match(state_filter, p))
8277 			sched_show_task(p);
8278 	}
8279 
8280 #ifdef CONFIG_SCHED_DEBUG
8281 	if (!state_filter)
8282 		sysrq_sched_debug_show();
8283 #endif
8284 	rcu_read_unlock();
8285 	/*
8286 	 * Only show locks if all tasks are dumped:
8287 	 */
8288 	if (!state_filter)
8289 		debug_show_all_locks();
8290 }
8291 
8292 /**
8293  * init_idle - set up an idle thread for a given CPU
8294  * @idle: task in question
8295  * @cpu: CPU the idle task belongs to
8296  *
8297  * NOTE: this function does not set the idle thread's NEED_RESCHED
8298  * flag, to make booting more robust.
8299  */
8300 void __init init_idle(struct task_struct *idle, int cpu)
8301 {
8302 	struct rq *rq = cpu_rq(cpu);
8303 	unsigned long flags;
8304 
8305 	__sched_fork(0, idle);
8306 
8307 	/*
8308 	 * The idle task doesn't need the kthread struct to function, but it
8309 	 * is dressed up as a per-CPU kthread and thus needs to play the part
8310 	 * if we want to avoid special-casing it in code that deals with per-CPU
8311 	 * kthreads.
8312 	 */
8313 	set_kthread_struct(idle);
8314 
8315 	raw_spin_lock_irqsave(&idle->pi_lock, flags);
8316 	raw_spin_rq_lock(rq);
8317 
8318 	idle->__state = TASK_RUNNING;
8319 	idle->se.exec_start = sched_clock();
8320 	/*
8321 	 * PF_KTHREAD should already be set at this point; regardless, make it
8322 	 * look like a proper per-CPU kthread.
8323 	 */
8324 	idle->flags |= PF_IDLE | PF_KTHREAD | PF_NO_SETAFFINITY;
8325 	kthread_set_per_cpu(idle, cpu);
8326 
8327 	scs_task_reset(idle);
8328 	kasan_unpoison_task_stack(idle);
8329 
8330 #ifdef CONFIG_SMP
8331 	/*
8332 	 * It's possible that init_idle() gets called multiple times on a task,
8333 	 * in that case do_set_cpus_allowed() will not do the right thing.
8334 	 *
8335 	 * And since this is boot we can forgo the serialization.
8336 	 */
8337 	set_cpus_allowed_common(idle, cpumask_of(cpu), 0);
8338 #endif
8339 	/*
8340 	 * We're having a chicken and egg problem, even though we are
8341 	 * holding rq->lock, the CPU isn't yet set to this CPU so the
8342 	 * lockdep check in task_group() will fail.
8343 	 *
8344 	 * Similar case to sched_fork(). / Alternatively we could
8345 	 * use task_rq_lock() here and obtain the other rq->lock.
8346 	 *
8347 	 * Silence PROVE_RCU
8348 	 */
8349 	rcu_read_lock();
8350 	__set_task_cpu(idle, cpu);
8351 	rcu_read_unlock();
8352 
8353 	rq->idle = idle;
8354 	rcu_assign_pointer(rq->curr, idle);
8355 	idle->on_rq = TASK_ON_RQ_QUEUED;
8356 #ifdef CONFIG_SMP
8357 	idle->on_cpu = 1;
8358 #endif
8359 	raw_spin_rq_unlock(rq);
8360 	raw_spin_unlock_irqrestore(&idle->pi_lock, flags);
8361 
8362 	/* Set the preempt count _outside_ the spinlocks! */
8363 	init_idle_preempt_count(idle, cpu);
8364 
8365 	/*
8366 	 * The idle tasks have their own, simple scheduling class:
8367 	 */
8368 	idle->sched_class = &idle_sched_class;
8369 	ftrace_graph_init_idle_task(idle, cpu);
8370 	vtime_init_idle(idle, cpu);
8371 #ifdef CONFIG_SMP
8372 	sprintf(idle->comm, "%s/%d", INIT_TASK_COMM, cpu);
8373 #endif
8374 }
8375 
8376 #ifdef CONFIG_SMP
8377 
8378 int cpuset_cpumask_can_shrink(const struct cpumask *cur,
8379 			      const struct cpumask *trial)
8380 {
8381 	int ret = 1;
8382 
8383 	if (!cpumask_weight(cur))
8384 		return ret;
8385 
8386 	ret = dl_cpuset_cpumask_can_shrink(cur, trial);
8387 
8388 	return ret;
8389 }
8390 
8391 int task_can_attach(struct task_struct *p,
8392 		    const struct cpumask *cs_cpus_allowed)
8393 {
8394 	int ret = 0;
8395 
8396 	/*
8397 	 * Kthreads which disallow setaffinity shouldn't be moved
8398 	 * to a new cpuset; we don't want to change their CPU
8399 	 * affinity and isolating such threads by their set of
8400 	 * allowed nodes is unnecessary.  Thus, cpusets are not
8401 	 * applicable for such threads.  This prevents checking for
8402 	 * success of set_cpus_allowed_ptr() on all attached tasks
8403 	 * before cpus_mask may be changed.
8404 	 */
8405 	if (p->flags & PF_NO_SETAFFINITY) {
8406 		ret = -EINVAL;
8407 		goto out;
8408 	}
8409 
8410 	if (dl_task(p) && !cpumask_intersects(task_rq(p)->rd->span,
8411 					      cs_cpus_allowed))
8412 		ret = dl_task_can_attach(p, cs_cpus_allowed);
8413 
8414 out:
8415 	return ret;
8416 }
8417 
8418 bool sched_smp_initialized __read_mostly;
8419 
8420 #ifdef CONFIG_NUMA_BALANCING
8421 /* Migrate current task p to target_cpu */
8422 int migrate_task_to(struct task_struct *p, int target_cpu)
8423 {
8424 	struct migration_arg arg = { p, target_cpu };
8425 	int curr_cpu = task_cpu(p);
8426 
8427 	if (curr_cpu == target_cpu)
8428 		return 0;
8429 
8430 	if (!cpumask_test_cpu(target_cpu, p->cpus_ptr))
8431 		return -EINVAL;
8432 
8433 	/* TODO: This is not properly updating schedstats */
8434 
8435 	trace_sched_move_numa(p, curr_cpu, target_cpu);
8436 	return stop_one_cpu(curr_cpu, migration_cpu_stop, &arg);
8437 }
8438 
8439 /*
8440  * Requeue a task on a given node and accurately track the number of NUMA
8441  * tasks on the runqueues
8442  */
8443 void sched_setnuma(struct task_struct *p, int nid)
8444 {
8445 	bool queued, running;
8446 	struct rq_flags rf;
8447 	struct rq *rq;
8448 
8449 	rq = task_rq_lock(p, &rf);
8450 	queued = task_on_rq_queued(p);
8451 	running = task_current(rq, p);
8452 
8453 	if (queued)
8454 		dequeue_task(rq, p, DEQUEUE_SAVE);
8455 	if (running)
8456 		put_prev_task(rq, p);
8457 
8458 	p->numa_preferred_nid = nid;
8459 
8460 	if (queued)
8461 		enqueue_task(rq, p, ENQUEUE_RESTORE | ENQUEUE_NOCLOCK);
8462 	if (running)
8463 		set_next_task(rq, p);
8464 	task_rq_unlock(rq, p, &rf);
8465 }
8466 #endif /* CONFIG_NUMA_BALANCING */
8467 
8468 #ifdef CONFIG_HOTPLUG_CPU
8469 /*
8470  * Ensure that the idle task is using init_mm right before its CPU goes
8471  * offline.
8472  */
8473 void idle_task_exit(void)
8474 {
8475 	struct mm_struct *mm = current->active_mm;
8476 
8477 	BUG_ON(cpu_online(smp_processor_id()));
8478 	BUG_ON(current != this_rq()->idle);
8479 
8480 	if (mm != &init_mm) {
8481 		switch_mm(mm, &init_mm, current);
8482 		finish_arch_post_lock_switch();
8483 	}
8484 
8485 	/* finish_cpu(), as ran on the BP, will clean up the active_mm state */
8486 }
8487 
8488 static int __balance_push_cpu_stop(void *arg)
8489 {
8490 	struct task_struct *p = arg;
8491 	struct rq *rq = this_rq();
8492 	struct rq_flags rf;
8493 	int cpu;
8494 
8495 	raw_spin_lock_irq(&p->pi_lock);
8496 	rq_lock(rq, &rf);
8497 
8498 	update_rq_clock(rq);
8499 
8500 	if (task_rq(p) == rq && task_on_rq_queued(p)) {
8501 		cpu = select_fallback_rq(rq->cpu, p);
8502 		rq = __migrate_task(rq, &rf, p, cpu);
8503 	}
8504 
8505 	rq_unlock(rq, &rf);
8506 	raw_spin_unlock_irq(&p->pi_lock);
8507 
8508 	put_task_struct(p);
8509 
8510 	return 0;
8511 }
8512 
8513 static DEFINE_PER_CPU(struct cpu_stop_work, push_work);
8514 
8515 /*
8516  * Ensure we only run per-cpu kthreads once the CPU goes !active.
8517  *
8518  * This is enabled below SCHED_AP_ACTIVE; when !cpu_active(), but only
8519  * effective when the hotplug motion is down.
8520  */
8521 static void balance_push(struct rq *rq)
8522 {
8523 	struct task_struct *push_task = rq->curr;
8524 
8525 	lockdep_assert_rq_held(rq);
8526 	SCHED_WARN_ON(rq->cpu != smp_processor_id());
8527 
8528 	/*
8529 	 * Ensure the thing is persistent until balance_push_set(.on = false);
8530 	 */
8531 	rq->balance_callback = &balance_push_callback;
8532 
8533 	/*
8534 	 * Only active while going offline.
8535 	 */
8536 	if (!cpu_dying(rq->cpu))
8537 		return;
8538 
8539 	/*
8540 	 * Both the cpu-hotplug and stop task are in this case and are
8541 	 * required to complete the hotplug process.
8542 	 */
8543 	if (kthread_is_per_cpu(push_task) ||
8544 	    is_migration_disabled(push_task)) {
8545 
8546 		/*
8547 		 * If this is the idle task on the outgoing CPU try to wake
8548 		 * up the hotplug control thread which might wait for the
8549 		 * last task to vanish. The rcuwait_active() check is
8550 		 * accurate here because the waiter is pinned on this CPU
8551 		 * and can't obviously be running in parallel.
8552 		 *
8553 		 * On RT kernels this also has to check whether there are
8554 		 * pinned and scheduled out tasks on the runqueue. They
8555 		 * need to leave the migrate disabled section first.
8556 		 */
8557 		if (!rq->nr_running && !rq_has_pinned_tasks(rq) &&
8558 		    rcuwait_active(&rq->hotplug_wait)) {
8559 			raw_spin_rq_unlock(rq);
8560 			rcuwait_wake_up(&rq->hotplug_wait);
8561 			raw_spin_rq_lock(rq);
8562 		}
8563 		return;
8564 	}
8565 
8566 	get_task_struct(push_task);
8567 	/*
8568 	 * Temporarily drop rq->lock such that we can wake-up the stop task.
8569 	 * Both preemption and IRQs are still disabled.
8570 	 */
8571 	raw_spin_rq_unlock(rq);
8572 	stop_one_cpu_nowait(rq->cpu, __balance_push_cpu_stop, push_task,
8573 			    this_cpu_ptr(&push_work));
8574 	/*
8575 	 * At this point need_resched() is true and we'll take the loop in
8576 	 * schedule(). The next pick is obviously going to be the stop task
8577 	 * which kthread_is_per_cpu() and will push this task away.
8578 	 */
8579 	raw_spin_rq_lock(rq);
8580 }
8581 
8582 static void balance_push_set(int cpu, bool on)
8583 {
8584 	struct rq *rq = cpu_rq(cpu);
8585 	struct rq_flags rf;
8586 
8587 	rq_lock_irqsave(rq, &rf);
8588 	if (on) {
8589 		WARN_ON_ONCE(rq->balance_callback);
8590 		rq->balance_callback = &balance_push_callback;
8591 	} else if (rq->balance_callback == &balance_push_callback) {
8592 		rq->balance_callback = NULL;
8593 	}
8594 	rq_unlock_irqrestore(rq, &rf);
8595 }
8596 
8597 /*
8598  * Invoked from a CPUs hotplug control thread after the CPU has been marked
8599  * inactive. All tasks which are not per CPU kernel threads are either
8600  * pushed off this CPU now via balance_push() or placed on a different CPU
8601  * during wakeup. Wait until the CPU is quiescent.
8602  */
8603 static void balance_hotplug_wait(void)
8604 {
8605 	struct rq *rq = this_rq();
8606 
8607 	rcuwait_wait_event(&rq->hotplug_wait,
8608 			   rq->nr_running == 1 && !rq_has_pinned_tasks(rq),
8609 			   TASK_UNINTERRUPTIBLE);
8610 }
8611 
8612 #else
8613 
8614 static inline void balance_push(struct rq *rq)
8615 {
8616 }
8617 
8618 static inline void balance_push_set(int cpu, bool on)
8619 {
8620 }
8621 
8622 static inline void balance_hotplug_wait(void)
8623 {
8624 }
8625 
8626 #endif /* CONFIG_HOTPLUG_CPU */
8627 
8628 void set_rq_online(struct rq *rq)
8629 {
8630 	if (!rq->online) {
8631 		const struct sched_class *class;
8632 
8633 		cpumask_set_cpu(rq->cpu, rq->rd->online);
8634 		rq->online = 1;
8635 
8636 		for_each_class(class) {
8637 			if (class->rq_online)
8638 				class->rq_online(rq);
8639 		}
8640 	}
8641 }
8642 
8643 void set_rq_offline(struct rq *rq)
8644 {
8645 	if (rq->online) {
8646 		const struct sched_class *class;
8647 
8648 		for_each_class(class) {
8649 			if (class->rq_offline)
8650 				class->rq_offline(rq);
8651 		}
8652 
8653 		cpumask_clear_cpu(rq->cpu, rq->rd->online);
8654 		rq->online = 0;
8655 	}
8656 }
8657 
8658 /*
8659  * used to mark begin/end of suspend/resume:
8660  */
8661 static int num_cpus_frozen;
8662 
8663 /*
8664  * Update cpusets according to cpu_active mask.  If cpusets are
8665  * disabled, cpuset_update_active_cpus() becomes a simple wrapper
8666  * around partition_sched_domains().
8667  *
8668  * If we come here as part of a suspend/resume, don't touch cpusets because we
8669  * want to restore it back to its original state upon resume anyway.
8670  */
8671 static void cpuset_cpu_active(void)
8672 {
8673 	if (cpuhp_tasks_frozen) {
8674 		/*
8675 		 * num_cpus_frozen tracks how many CPUs are involved in suspend
8676 		 * resume sequence. As long as this is not the last online
8677 		 * operation in the resume sequence, just build a single sched
8678 		 * domain, ignoring cpusets.
8679 		 */
8680 		partition_sched_domains(1, NULL, NULL);
8681 		if (--num_cpus_frozen)
8682 			return;
8683 		/*
8684 		 * This is the last CPU online operation. So fall through and
8685 		 * restore the original sched domains by considering the
8686 		 * cpuset configurations.
8687 		 */
8688 		cpuset_force_rebuild();
8689 	}
8690 	cpuset_update_active_cpus();
8691 }
8692 
8693 static int cpuset_cpu_inactive(unsigned int cpu)
8694 {
8695 	if (!cpuhp_tasks_frozen) {
8696 		if (dl_cpu_busy(cpu))
8697 			return -EBUSY;
8698 		cpuset_update_active_cpus();
8699 	} else {
8700 		num_cpus_frozen++;
8701 		partition_sched_domains(1, NULL, NULL);
8702 	}
8703 	return 0;
8704 }
8705 
8706 int sched_cpu_activate(unsigned int cpu)
8707 {
8708 	struct rq *rq = cpu_rq(cpu);
8709 	struct rq_flags rf;
8710 
8711 	/*
8712 	 * Clear the balance_push callback and prepare to schedule
8713 	 * regular tasks.
8714 	 */
8715 	balance_push_set(cpu, false);
8716 
8717 #ifdef CONFIG_SCHED_SMT
8718 	/*
8719 	 * When going up, increment the number of cores with SMT present.
8720 	 */
8721 	if (cpumask_weight(cpu_smt_mask(cpu)) == 2)
8722 		static_branch_inc_cpuslocked(&sched_smt_present);
8723 #endif
8724 	set_cpu_active(cpu, true);
8725 
8726 	if (sched_smp_initialized) {
8727 		sched_domains_numa_masks_set(cpu);
8728 		cpuset_cpu_active();
8729 	}
8730 
8731 	/*
8732 	 * Put the rq online, if not already. This happens:
8733 	 *
8734 	 * 1) In the early boot process, because we build the real domains
8735 	 *    after all CPUs have been brought up.
8736 	 *
8737 	 * 2) At runtime, if cpuset_cpu_active() fails to rebuild the
8738 	 *    domains.
8739 	 */
8740 	rq_lock_irqsave(rq, &rf);
8741 	if (rq->rd) {
8742 		BUG_ON(!cpumask_test_cpu(cpu, rq->rd->span));
8743 		set_rq_online(rq);
8744 	}
8745 	rq_unlock_irqrestore(rq, &rf);
8746 
8747 	return 0;
8748 }
8749 
8750 int sched_cpu_deactivate(unsigned int cpu)
8751 {
8752 	struct rq *rq = cpu_rq(cpu);
8753 	struct rq_flags rf;
8754 	int ret;
8755 
8756 	/*
8757 	 * Remove CPU from nohz.idle_cpus_mask to prevent participating in
8758 	 * load balancing when not active
8759 	 */
8760 	nohz_balance_exit_idle(rq);
8761 
8762 	set_cpu_active(cpu, false);
8763 
8764 	/*
8765 	 * From this point forward, this CPU will refuse to run any task that
8766 	 * is not: migrate_disable() or KTHREAD_IS_PER_CPU, and will actively
8767 	 * push those tasks away until this gets cleared, see
8768 	 * sched_cpu_dying().
8769 	 */
8770 	balance_push_set(cpu, true);
8771 
8772 	/*
8773 	 * We've cleared cpu_active_mask / set balance_push, wait for all
8774 	 * preempt-disabled and RCU users of this state to go away such that
8775 	 * all new such users will observe it.
8776 	 *
8777 	 * Specifically, we rely on ttwu to no longer target this CPU, see
8778 	 * ttwu_queue_cond() and is_cpu_allowed().
8779 	 *
8780 	 * Do sync before park smpboot threads to take care the rcu boost case.
8781 	 */
8782 	synchronize_rcu();
8783 
8784 	rq_lock_irqsave(rq, &rf);
8785 	if (rq->rd) {
8786 		update_rq_clock(rq);
8787 		BUG_ON(!cpumask_test_cpu(cpu, rq->rd->span));
8788 		set_rq_offline(rq);
8789 	}
8790 	rq_unlock_irqrestore(rq, &rf);
8791 
8792 #ifdef CONFIG_SCHED_SMT
8793 	/*
8794 	 * When going down, decrement the number of cores with SMT present.
8795 	 */
8796 	if (cpumask_weight(cpu_smt_mask(cpu)) == 2)
8797 		static_branch_dec_cpuslocked(&sched_smt_present);
8798 
8799 	sched_core_cpu_deactivate(cpu);
8800 #endif
8801 
8802 	if (!sched_smp_initialized)
8803 		return 0;
8804 
8805 	ret = cpuset_cpu_inactive(cpu);
8806 	if (ret) {
8807 		balance_push_set(cpu, false);
8808 		set_cpu_active(cpu, true);
8809 		return ret;
8810 	}
8811 	sched_domains_numa_masks_clear(cpu);
8812 	return 0;
8813 }
8814 
8815 static void sched_rq_cpu_starting(unsigned int cpu)
8816 {
8817 	struct rq *rq = cpu_rq(cpu);
8818 
8819 	rq->calc_load_update = calc_load_update;
8820 	update_max_interval();
8821 }
8822 
8823 int sched_cpu_starting(unsigned int cpu)
8824 {
8825 	sched_core_cpu_starting(cpu);
8826 	sched_rq_cpu_starting(cpu);
8827 	sched_tick_start(cpu);
8828 	return 0;
8829 }
8830 
8831 #ifdef CONFIG_HOTPLUG_CPU
8832 
8833 /*
8834  * Invoked immediately before the stopper thread is invoked to bring the
8835  * CPU down completely. At this point all per CPU kthreads except the
8836  * hotplug thread (current) and the stopper thread (inactive) have been
8837  * either parked or have been unbound from the outgoing CPU. Ensure that
8838  * any of those which might be on the way out are gone.
8839  *
8840  * If after this point a bound task is being woken on this CPU then the
8841  * responsible hotplug callback has failed to do it's job.
8842  * sched_cpu_dying() will catch it with the appropriate fireworks.
8843  */
8844 int sched_cpu_wait_empty(unsigned int cpu)
8845 {
8846 	balance_hotplug_wait();
8847 	return 0;
8848 }
8849 
8850 /*
8851  * Since this CPU is going 'away' for a while, fold any nr_active delta we
8852  * might have. Called from the CPU stopper task after ensuring that the
8853  * stopper is the last running task on the CPU, so nr_active count is
8854  * stable. We need to take the teardown thread which is calling this into
8855  * account, so we hand in adjust = 1 to the load calculation.
8856  *
8857  * Also see the comment "Global load-average calculations".
8858  */
8859 static void calc_load_migrate(struct rq *rq)
8860 {
8861 	long delta = calc_load_fold_active(rq, 1);
8862 
8863 	if (delta)
8864 		atomic_long_add(delta, &calc_load_tasks);
8865 }
8866 
8867 static void dump_rq_tasks(struct rq *rq, const char *loglvl)
8868 {
8869 	struct task_struct *g, *p;
8870 	int cpu = cpu_of(rq);
8871 
8872 	lockdep_assert_rq_held(rq);
8873 
8874 	printk("%sCPU%d enqueued tasks (%u total):\n", loglvl, cpu, rq->nr_running);
8875 	for_each_process_thread(g, p) {
8876 		if (task_cpu(p) != cpu)
8877 			continue;
8878 
8879 		if (!task_on_rq_queued(p))
8880 			continue;
8881 
8882 		printk("%s\tpid: %d, name: %s\n", loglvl, p->pid, p->comm);
8883 	}
8884 }
8885 
8886 int sched_cpu_dying(unsigned int cpu)
8887 {
8888 	struct rq *rq = cpu_rq(cpu);
8889 	struct rq_flags rf;
8890 
8891 	/* Handle pending wakeups and then migrate everything off */
8892 	sched_tick_stop(cpu);
8893 
8894 	rq_lock_irqsave(rq, &rf);
8895 	if (rq->nr_running != 1 || rq_has_pinned_tasks(rq)) {
8896 		WARN(true, "Dying CPU not properly vacated!");
8897 		dump_rq_tasks(rq, KERN_WARNING);
8898 	}
8899 	rq_unlock_irqrestore(rq, &rf);
8900 
8901 	calc_load_migrate(rq);
8902 	update_max_interval();
8903 	hrtick_clear(rq);
8904 	sched_core_cpu_dying(cpu);
8905 	return 0;
8906 }
8907 #endif
8908 
8909 void __init sched_init_smp(void)
8910 {
8911 	sched_init_numa();
8912 
8913 	/*
8914 	 * There's no userspace yet to cause hotplug operations; hence all the
8915 	 * CPU masks are stable and all blatant races in the below code cannot
8916 	 * happen.
8917 	 */
8918 	mutex_lock(&sched_domains_mutex);
8919 	sched_init_domains(cpu_active_mask);
8920 	mutex_unlock(&sched_domains_mutex);
8921 
8922 	/* Move init over to a non-isolated CPU */
8923 	if (set_cpus_allowed_ptr(current, housekeeping_cpumask(HK_FLAG_DOMAIN)) < 0)
8924 		BUG();
8925 	current->flags &= ~PF_NO_SETAFFINITY;
8926 	sched_init_granularity();
8927 
8928 	init_sched_rt_class();
8929 	init_sched_dl_class();
8930 
8931 	sched_smp_initialized = true;
8932 }
8933 
8934 static int __init migration_init(void)
8935 {
8936 	sched_cpu_starting(smp_processor_id());
8937 	return 0;
8938 }
8939 early_initcall(migration_init);
8940 
8941 #else
8942 void __init sched_init_smp(void)
8943 {
8944 	sched_init_granularity();
8945 }
8946 #endif /* CONFIG_SMP */
8947 
8948 int in_sched_functions(unsigned long addr)
8949 {
8950 	return in_lock_functions(addr) ||
8951 		(addr >= (unsigned long)__sched_text_start
8952 		&& addr < (unsigned long)__sched_text_end);
8953 }
8954 
8955 #ifdef CONFIG_CGROUP_SCHED
8956 /*
8957  * Default task group.
8958  * Every task in system belongs to this group at bootup.
8959  */
8960 struct task_group root_task_group;
8961 LIST_HEAD(task_groups);
8962 
8963 /* Cacheline aligned slab cache for task_group */
8964 static struct kmem_cache *task_group_cache __read_mostly;
8965 #endif
8966 
8967 DECLARE_PER_CPU(cpumask_var_t, load_balance_mask);
8968 DECLARE_PER_CPU(cpumask_var_t, select_idle_mask);
8969 
8970 void __init sched_init(void)
8971 {
8972 	unsigned long ptr = 0;
8973 	int i;
8974 
8975 	/* Make sure the linker didn't screw up */
8976 	BUG_ON(&idle_sched_class + 1 != &fair_sched_class ||
8977 	       &fair_sched_class + 1 != &rt_sched_class ||
8978 	       &rt_sched_class + 1   != &dl_sched_class);
8979 #ifdef CONFIG_SMP
8980 	BUG_ON(&dl_sched_class + 1 != &stop_sched_class);
8981 #endif
8982 
8983 	wait_bit_init();
8984 
8985 #ifdef CONFIG_FAIR_GROUP_SCHED
8986 	ptr += 2 * nr_cpu_ids * sizeof(void **);
8987 #endif
8988 #ifdef CONFIG_RT_GROUP_SCHED
8989 	ptr += 2 * nr_cpu_ids * sizeof(void **);
8990 #endif
8991 	if (ptr) {
8992 		ptr = (unsigned long)kzalloc(ptr, GFP_NOWAIT);
8993 
8994 #ifdef CONFIG_FAIR_GROUP_SCHED
8995 		root_task_group.se = (struct sched_entity **)ptr;
8996 		ptr += nr_cpu_ids * sizeof(void **);
8997 
8998 		root_task_group.cfs_rq = (struct cfs_rq **)ptr;
8999 		ptr += nr_cpu_ids * sizeof(void **);
9000 
9001 		root_task_group.shares = ROOT_TASK_GROUP_LOAD;
9002 		init_cfs_bandwidth(&root_task_group.cfs_bandwidth);
9003 #endif /* CONFIG_FAIR_GROUP_SCHED */
9004 #ifdef CONFIG_RT_GROUP_SCHED
9005 		root_task_group.rt_se = (struct sched_rt_entity **)ptr;
9006 		ptr += nr_cpu_ids * sizeof(void **);
9007 
9008 		root_task_group.rt_rq = (struct rt_rq **)ptr;
9009 		ptr += nr_cpu_ids * sizeof(void **);
9010 
9011 #endif /* CONFIG_RT_GROUP_SCHED */
9012 	}
9013 #ifdef CONFIG_CPUMASK_OFFSTACK
9014 	for_each_possible_cpu(i) {
9015 		per_cpu(load_balance_mask, i) = (cpumask_var_t)kzalloc_node(
9016 			cpumask_size(), GFP_KERNEL, cpu_to_node(i));
9017 		per_cpu(select_idle_mask, i) = (cpumask_var_t)kzalloc_node(
9018 			cpumask_size(), GFP_KERNEL, cpu_to_node(i));
9019 	}
9020 #endif /* CONFIG_CPUMASK_OFFSTACK */
9021 
9022 	init_rt_bandwidth(&def_rt_bandwidth, global_rt_period(), global_rt_runtime());
9023 	init_dl_bandwidth(&def_dl_bandwidth, global_rt_period(), global_rt_runtime());
9024 
9025 #ifdef CONFIG_SMP
9026 	init_defrootdomain();
9027 #endif
9028 
9029 #ifdef CONFIG_RT_GROUP_SCHED
9030 	init_rt_bandwidth(&root_task_group.rt_bandwidth,
9031 			global_rt_period(), global_rt_runtime());
9032 #endif /* CONFIG_RT_GROUP_SCHED */
9033 
9034 #ifdef CONFIG_CGROUP_SCHED
9035 	task_group_cache = KMEM_CACHE(task_group, 0);
9036 
9037 	list_add(&root_task_group.list, &task_groups);
9038 	INIT_LIST_HEAD(&root_task_group.children);
9039 	INIT_LIST_HEAD(&root_task_group.siblings);
9040 	autogroup_init(&init_task);
9041 #endif /* CONFIG_CGROUP_SCHED */
9042 
9043 	for_each_possible_cpu(i) {
9044 		struct rq *rq;
9045 
9046 		rq = cpu_rq(i);
9047 		raw_spin_lock_init(&rq->__lock);
9048 		rq->nr_running = 0;
9049 		rq->calc_load_active = 0;
9050 		rq->calc_load_update = jiffies + LOAD_FREQ;
9051 		init_cfs_rq(&rq->cfs);
9052 		init_rt_rq(&rq->rt);
9053 		init_dl_rq(&rq->dl);
9054 #ifdef CONFIG_FAIR_GROUP_SCHED
9055 		INIT_LIST_HEAD(&rq->leaf_cfs_rq_list);
9056 		rq->tmp_alone_branch = &rq->leaf_cfs_rq_list;
9057 		/*
9058 		 * How much CPU bandwidth does root_task_group get?
9059 		 *
9060 		 * In case of task-groups formed thr' the cgroup filesystem, it
9061 		 * gets 100% of the CPU resources in the system. This overall
9062 		 * system CPU resource is divided among the tasks of
9063 		 * root_task_group and its child task-groups in a fair manner,
9064 		 * based on each entity's (task or task-group's) weight
9065 		 * (se->load.weight).
9066 		 *
9067 		 * In other words, if root_task_group has 10 tasks of weight
9068 		 * 1024) and two child groups A0 and A1 (of weight 1024 each),
9069 		 * then A0's share of the CPU resource is:
9070 		 *
9071 		 *	A0's bandwidth = 1024 / (10*1024 + 1024 + 1024) = 8.33%
9072 		 *
9073 		 * We achieve this by letting root_task_group's tasks sit
9074 		 * directly in rq->cfs (i.e root_task_group->se[] = NULL).
9075 		 */
9076 		init_tg_cfs_entry(&root_task_group, &rq->cfs, NULL, i, NULL);
9077 #endif /* CONFIG_FAIR_GROUP_SCHED */
9078 
9079 		rq->rt.rt_runtime = def_rt_bandwidth.rt_runtime;
9080 #ifdef CONFIG_RT_GROUP_SCHED
9081 		init_tg_rt_entry(&root_task_group, &rq->rt, NULL, i, NULL);
9082 #endif
9083 #ifdef CONFIG_SMP
9084 		rq->sd = NULL;
9085 		rq->rd = NULL;
9086 		rq->cpu_capacity = rq->cpu_capacity_orig = SCHED_CAPACITY_SCALE;
9087 		rq->balance_callback = &balance_push_callback;
9088 		rq->active_balance = 0;
9089 		rq->next_balance = jiffies;
9090 		rq->push_cpu = 0;
9091 		rq->cpu = i;
9092 		rq->online = 0;
9093 		rq->idle_stamp = 0;
9094 		rq->avg_idle = 2*sysctl_sched_migration_cost;
9095 		rq->wake_stamp = jiffies;
9096 		rq->wake_avg_idle = rq->avg_idle;
9097 		rq->max_idle_balance_cost = sysctl_sched_migration_cost;
9098 
9099 		INIT_LIST_HEAD(&rq->cfs_tasks);
9100 
9101 		rq_attach_root(rq, &def_root_domain);
9102 #ifdef CONFIG_NO_HZ_COMMON
9103 		rq->last_blocked_load_update_tick = jiffies;
9104 		atomic_set(&rq->nohz_flags, 0);
9105 
9106 		INIT_CSD(&rq->nohz_csd, nohz_csd_func, rq);
9107 #endif
9108 #ifdef CONFIG_HOTPLUG_CPU
9109 		rcuwait_init(&rq->hotplug_wait);
9110 #endif
9111 #endif /* CONFIG_SMP */
9112 		hrtick_rq_init(rq);
9113 		atomic_set(&rq->nr_iowait, 0);
9114 
9115 #ifdef CONFIG_SCHED_CORE
9116 		rq->core = rq;
9117 		rq->core_pick = NULL;
9118 		rq->core_enabled = 0;
9119 		rq->core_tree = RB_ROOT;
9120 		rq->core_forceidle = false;
9121 
9122 		rq->core_cookie = 0UL;
9123 #endif
9124 	}
9125 
9126 	set_load_weight(&init_task, false);
9127 
9128 	/*
9129 	 * The boot idle thread does lazy MMU switching as well:
9130 	 */
9131 	mmgrab(&init_mm);
9132 	enter_lazy_tlb(&init_mm, current);
9133 
9134 	/*
9135 	 * Make us the idle thread. Technically, schedule() should not be
9136 	 * called from this thread, however somewhere below it might be,
9137 	 * but because we are the idle thread, we just pick up running again
9138 	 * when this runqueue becomes "idle".
9139 	 */
9140 	init_idle(current, smp_processor_id());
9141 
9142 	calc_load_update = jiffies + LOAD_FREQ;
9143 
9144 #ifdef CONFIG_SMP
9145 	idle_thread_set_boot_cpu();
9146 	balance_push_set(smp_processor_id(), false);
9147 #endif
9148 	init_sched_fair_class();
9149 
9150 	psi_init();
9151 
9152 	init_uclamp();
9153 
9154 	scheduler_running = 1;
9155 }
9156 
9157 #ifdef CONFIG_DEBUG_ATOMIC_SLEEP
9158 static inline int preempt_count_equals(int preempt_offset)
9159 {
9160 	int nested = preempt_count() + rcu_preempt_depth();
9161 
9162 	return (nested == preempt_offset);
9163 }
9164 
9165 void __might_sleep(const char *file, int line, int preempt_offset)
9166 {
9167 	unsigned int state = get_current_state();
9168 	/*
9169 	 * Blocking primitives will set (and therefore destroy) current->state,
9170 	 * since we will exit with TASK_RUNNING make sure we enter with it,
9171 	 * otherwise we will destroy state.
9172 	 */
9173 	WARN_ONCE(state != TASK_RUNNING && current->task_state_change,
9174 			"do not call blocking ops when !TASK_RUNNING; "
9175 			"state=%x set at [<%p>] %pS\n", state,
9176 			(void *)current->task_state_change,
9177 			(void *)current->task_state_change);
9178 
9179 	___might_sleep(file, line, preempt_offset);
9180 }
9181 EXPORT_SYMBOL(__might_sleep);
9182 
9183 void ___might_sleep(const char *file, int line, int preempt_offset)
9184 {
9185 	/* Ratelimiting timestamp: */
9186 	static unsigned long prev_jiffy;
9187 
9188 	unsigned long preempt_disable_ip;
9189 
9190 	/* WARN_ON_ONCE() by default, no rate limit required: */
9191 	rcu_sleep_check();
9192 
9193 	if ((preempt_count_equals(preempt_offset) && !irqs_disabled() &&
9194 	     !is_idle_task(current) && !current->non_block_count) ||
9195 	    system_state == SYSTEM_BOOTING || system_state > SYSTEM_RUNNING ||
9196 	    oops_in_progress)
9197 		return;
9198 
9199 	if (time_before(jiffies, prev_jiffy + HZ) && prev_jiffy)
9200 		return;
9201 	prev_jiffy = jiffies;
9202 
9203 	/* Save this before calling printk(), since that will clobber it: */
9204 	preempt_disable_ip = get_preempt_disable_ip(current);
9205 
9206 	printk(KERN_ERR
9207 		"BUG: sleeping function called from invalid context at %s:%d\n",
9208 			file, line);
9209 	printk(KERN_ERR
9210 		"in_atomic(): %d, irqs_disabled(): %d, non_block: %d, pid: %d, name: %s\n",
9211 			in_atomic(), irqs_disabled(), current->non_block_count,
9212 			current->pid, current->comm);
9213 
9214 	if (task_stack_end_corrupted(current))
9215 		printk(KERN_EMERG "Thread overran stack, or stack corrupted\n");
9216 
9217 	debug_show_held_locks(current);
9218 	if (irqs_disabled())
9219 		print_irqtrace_events(current);
9220 	if (IS_ENABLED(CONFIG_DEBUG_PREEMPT)
9221 	    && !preempt_count_equals(preempt_offset)) {
9222 		pr_err("Preemption disabled at:");
9223 		print_ip_sym(KERN_ERR, preempt_disable_ip);
9224 	}
9225 	dump_stack();
9226 	add_taint(TAINT_WARN, LOCKDEP_STILL_OK);
9227 }
9228 EXPORT_SYMBOL(___might_sleep);
9229 
9230 void __cant_sleep(const char *file, int line, int preempt_offset)
9231 {
9232 	static unsigned long prev_jiffy;
9233 
9234 	if (irqs_disabled())
9235 		return;
9236 
9237 	if (!IS_ENABLED(CONFIG_PREEMPT_COUNT))
9238 		return;
9239 
9240 	if (preempt_count() > preempt_offset)
9241 		return;
9242 
9243 	if (time_before(jiffies, prev_jiffy + HZ) && prev_jiffy)
9244 		return;
9245 	prev_jiffy = jiffies;
9246 
9247 	printk(KERN_ERR "BUG: assuming atomic context at %s:%d\n", file, line);
9248 	printk(KERN_ERR "in_atomic(): %d, irqs_disabled(): %d, pid: %d, name: %s\n",
9249 			in_atomic(), irqs_disabled(),
9250 			current->pid, current->comm);
9251 
9252 	debug_show_held_locks(current);
9253 	dump_stack();
9254 	add_taint(TAINT_WARN, LOCKDEP_STILL_OK);
9255 }
9256 EXPORT_SYMBOL_GPL(__cant_sleep);
9257 
9258 #ifdef CONFIG_SMP
9259 void __cant_migrate(const char *file, int line)
9260 {
9261 	static unsigned long prev_jiffy;
9262 
9263 	if (irqs_disabled())
9264 		return;
9265 
9266 	if (is_migration_disabled(current))
9267 		return;
9268 
9269 	if (!IS_ENABLED(CONFIG_PREEMPT_COUNT))
9270 		return;
9271 
9272 	if (preempt_count() > 0)
9273 		return;
9274 
9275 	if (time_before(jiffies, prev_jiffy + HZ) && prev_jiffy)
9276 		return;
9277 	prev_jiffy = jiffies;
9278 
9279 	pr_err("BUG: assuming non migratable context at %s:%d\n", file, line);
9280 	pr_err("in_atomic(): %d, irqs_disabled(): %d, migration_disabled() %u pid: %d, name: %s\n",
9281 	       in_atomic(), irqs_disabled(), is_migration_disabled(current),
9282 	       current->pid, current->comm);
9283 
9284 	debug_show_held_locks(current);
9285 	dump_stack();
9286 	add_taint(TAINT_WARN, LOCKDEP_STILL_OK);
9287 }
9288 EXPORT_SYMBOL_GPL(__cant_migrate);
9289 #endif
9290 #endif
9291 
9292 #ifdef CONFIG_MAGIC_SYSRQ
9293 void normalize_rt_tasks(void)
9294 {
9295 	struct task_struct *g, *p;
9296 	struct sched_attr attr = {
9297 		.sched_policy = SCHED_NORMAL,
9298 	};
9299 
9300 	read_lock(&tasklist_lock);
9301 	for_each_process_thread(g, p) {
9302 		/*
9303 		 * Only normalize user tasks:
9304 		 */
9305 		if (p->flags & PF_KTHREAD)
9306 			continue;
9307 
9308 		p->se.exec_start = 0;
9309 		schedstat_set(p->se.statistics.wait_start,  0);
9310 		schedstat_set(p->se.statistics.sleep_start, 0);
9311 		schedstat_set(p->se.statistics.block_start, 0);
9312 
9313 		if (!dl_task(p) && !rt_task(p)) {
9314 			/*
9315 			 * Renice negative nice level userspace
9316 			 * tasks back to 0:
9317 			 */
9318 			if (task_nice(p) < 0)
9319 				set_user_nice(p, 0);
9320 			continue;
9321 		}
9322 
9323 		__sched_setscheduler(p, &attr, false, false);
9324 	}
9325 	read_unlock(&tasklist_lock);
9326 }
9327 
9328 #endif /* CONFIG_MAGIC_SYSRQ */
9329 
9330 #if defined(CONFIG_IA64) || defined(CONFIG_KGDB_KDB)
9331 /*
9332  * These functions are only useful for the IA64 MCA handling, or kdb.
9333  *
9334  * They can only be called when the whole system has been
9335  * stopped - every CPU needs to be quiescent, and no scheduling
9336  * activity can take place. Using them for anything else would
9337  * be a serious bug, and as a result, they aren't even visible
9338  * under any other configuration.
9339  */
9340 
9341 /**
9342  * curr_task - return the current task for a given CPU.
9343  * @cpu: the processor in question.
9344  *
9345  * ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED!
9346  *
9347  * Return: The current task for @cpu.
9348  */
9349 struct task_struct *curr_task(int cpu)
9350 {
9351 	return cpu_curr(cpu);
9352 }
9353 
9354 #endif /* defined(CONFIG_IA64) || defined(CONFIG_KGDB_KDB) */
9355 
9356 #ifdef CONFIG_IA64
9357 /**
9358  * ia64_set_curr_task - set the current task for a given CPU.
9359  * @cpu: the processor in question.
9360  * @p: the task pointer to set.
9361  *
9362  * Description: This function must only be used when non-maskable interrupts
9363  * are serviced on a separate stack. It allows the architecture to switch the
9364  * notion of the current task on a CPU in a non-blocking manner. This function
9365  * must be called with all CPU's synchronized, and interrupts disabled, the
9366  * and caller must save the original value of the current task (see
9367  * curr_task() above) and restore that value before reenabling interrupts and
9368  * re-starting the system.
9369  *
9370  * ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED!
9371  */
9372 void ia64_set_curr_task(int cpu, struct task_struct *p)
9373 {
9374 	cpu_curr(cpu) = p;
9375 }
9376 
9377 #endif
9378 
9379 #ifdef CONFIG_CGROUP_SCHED
9380 /* task_group_lock serializes the addition/removal of task groups */
9381 static DEFINE_SPINLOCK(task_group_lock);
9382 
9383 static inline void alloc_uclamp_sched_group(struct task_group *tg,
9384 					    struct task_group *parent)
9385 {
9386 #ifdef CONFIG_UCLAMP_TASK_GROUP
9387 	enum uclamp_id clamp_id;
9388 
9389 	for_each_clamp_id(clamp_id) {
9390 		uclamp_se_set(&tg->uclamp_req[clamp_id],
9391 			      uclamp_none(clamp_id), false);
9392 		tg->uclamp[clamp_id] = parent->uclamp[clamp_id];
9393 	}
9394 #endif
9395 }
9396 
9397 static void sched_free_group(struct task_group *tg)
9398 {
9399 	free_fair_sched_group(tg);
9400 	free_rt_sched_group(tg);
9401 	autogroup_free(tg);
9402 	kmem_cache_free(task_group_cache, tg);
9403 }
9404 
9405 /* allocate runqueue etc for a new task group */
9406 struct task_group *sched_create_group(struct task_group *parent)
9407 {
9408 	struct task_group *tg;
9409 
9410 	tg = kmem_cache_alloc(task_group_cache, GFP_KERNEL | __GFP_ZERO);
9411 	if (!tg)
9412 		return ERR_PTR(-ENOMEM);
9413 
9414 	if (!alloc_fair_sched_group(tg, parent))
9415 		goto err;
9416 
9417 	if (!alloc_rt_sched_group(tg, parent))
9418 		goto err;
9419 
9420 	alloc_uclamp_sched_group(tg, parent);
9421 
9422 	return tg;
9423 
9424 err:
9425 	sched_free_group(tg);
9426 	return ERR_PTR(-ENOMEM);
9427 }
9428 
9429 void sched_online_group(struct task_group *tg, struct task_group *parent)
9430 {
9431 	unsigned long flags;
9432 
9433 	spin_lock_irqsave(&task_group_lock, flags);
9434 	list_add_rcu(&tg->list, &task_groups);
9435 
9436 	/* Root should already exist: */
9437 	WARN_ON(!parent);
9438 
9439 	tg->parent = parent;
9440 	INIT_LIST_HEAD(&tg->children);
9441 	list_add_rcu(&tg->siblings, &parent->children);
9442 	spin_unlock_irqrestore(&task_group_lock, flags);
9443 
9444 	online_fair_sched_group(tg);
9445 }
9446 
9447 /* rcu callback to free various structures associated with a task group */
9448 static void sched_free_group_rcu(struct rcu_head *rhp)
9449 {
9450 	/* Now it should be safe to free those cfs_rqs: */
9451 	sched_free_group(container_of(rhp, struct task_group, rcu));
9452 }
9453 
9454 void sched_destroy_group(struct task_group *tg)
9455 {
9456 	/* Wait for possible concurrent references to cfs_rqs complete: */
9457 	call_rcu(&tg->rcu, sched_free_group_rcu);
9458 }
9459 
9460 void sched_offline_group(struct task_group *tg)
9461 {
9462 	unsigned long flags;
9463 
9464 	/* End participation in shares distribution: */
9465 	unregister_fair_sched_group(tg);
9466 
9467 	spin_lock_irqsave(&task_group_lock, flags);
9468 	list_del_rcu(&tg->list);
9469 	list_del_rcu(&tg->siblings);
9470 	spin_unlock_irqrestore(&task_group_lock, flags);
9471 }
9472 
9473 static void sched_change_group(struct task_struct *tsk, int type)
9474 {
9475 	struct task_group *tg;
9476 
9477 	/*
9478 	 * All callers are synchronized by task_rq_lock(); we do not use RCU
9479 	 * which is pointless here. Thus, we pass "true" to task_css_check()
9480 	 * to prevent lockdep warnings.
9481 	 */
9482 	tg = container_of(task_css_check(tsk, cpu_cgrp_id, true),
9483 			  struct task_group, css);
9484 	tg = autogroup_task_group(tsk, tg);
9485 	tsk->sched_task_group = tg;
9486 
9487 #ifdef CONFIG_FAIR_GROUP_SCHED
9488 	if (tsk->sched_class->task_change_group)
9489 		tsk->sched_class->task_change_group(tsk, type);
9490 	else
9491 #endif
9492 		set_task_rq(tsk, task_cpu(tsk));
9493 }
9494 
9495 /*
9496  * Change task's runqueue when it moves between groups.
9497  *
9498  * The caller of this function should have put the task in its new group by
9499  * now. This function just updates tsk->se.cfs_rq and tsk->se.parent to reflect
9500  * its new group.
9501  */
9502 void sched_move_task(struct task_struct *tsk)
9503 {
9504 	int queued, running, queue_flags =
9505 		DEQUEUE_SAVE | DEQUEUE_MOVE | DEQUEUE_NOCLOCK;
9506 	struct rq_flags rf;
9507 	struct rq *rq;
9508 
9509 	rq = task_rq_lock(tsk, &rf);
9510 	update_rq_clock(rq);
9511 
9512 	running = task_current(rq, tsk);
9513 	queued = task_on_rq_queued(tsk);
9514 
9515 	if (queued)
9516 		dequeue_task(rq, tsk, queue_flags);
9517 	if (running)
9518 		put_prev_task(rq, tsk);
9519 
9520 	sched_change_group(tsk, TASK_MOVE_GROUP);
9521 
9522 	if (queued)
9523 		enqueue_task(rq, tsk, queue_flags);
9524 	if (running) {
9525 		set_next_task(rq, tsk);
9526 		/*
9527 		 * After changing group, the running task may have joined a
9528 		 * throttled one but it's still the running task. Trigger a
9529 		 * resched to make sure that task can still run.
9530 		 */
9531 		resched_curr(rq);
9532 	}
9533 
9534 	task_rq_unlock(rq, tsk, &rf);
9535 }
9536 
9537 static inline struct task_group *css_tg(struct cgroup_subsys_state *css)
9538 {
9539 	return css ? container_of(css, struct task_group, css) : NULL;
9540 }
9541 
9542 static struct cgroup_subsys_state *
9543 cpu_cgroup_css_alloc(struct cgroup_subsys_state *parent_css)
9544 {
9545 	struct task_group *parent = css_tg(parent_css);
9546 	struct task_group *tg;
9547 
9548 	if (!parent) {
9549 		/* This is early initialization for the top cgroup */
9550 		return &root_task_group.css;
9551 	}
9552 
9553 	tg = sched_create_group(parent);
9554 	if (IS_ERR(tg))
9555 		return ERR_PTR(-ENOMEM);
9556 
9557 	return &tg->css;
9558 }
9559 
9560 /* Expose task group only after completing cgroup initialization */
9561 static int cpu_cgroup_css_online(struct cgroup_subsys_state *css)
9562 {
9563 	struct task_group *tg = css_tg(css);
9564 	struct task_group *parent = css_tg(css->parent);
9565 
9566 	if (parent)
9567 		sched_online_group(tg, parent);
9568 
9569 #ifdef CONFIG_UCLAMP_TASK_GROUP
9570 	/* Propagate the effective uclamp value for the new group */
9571 	mutex_lock(&uclamp_mutex);
9572 	rcu_read_lock();
9573 	cpu_util_update_eff(css);
9574 	rcu_read_unlock();
9575 	mutex_unlock(&uclamp_mutex);
9576 #endif
9577 
9578 	return 0;
9579 }
9580 
9581 static void cpu_cgroup_css_released(struct cgroup_subsys_state *css)
9582 {
9583 	struct task_group *tg = css_tg(css);
9584 
9585 	sched_offline_group(tg);
9586 }
9587 
9588 static void cpu_cgroup_css_free(struct cgroup_subsys_state *css)
9589 {
9590 	struct task_group *tg = css_tg(css);
9591 
9592 	/*
9593 	 * Relies on the RCU grace period between css_released() and this.
9594 	 */
9595 	sched_free_group(tg);
9596 }
9597 
9598 /*
9599  * This is called before wake_up_new_task(), therefore we really only
9600  * have to set its group bits, all the other stuff does not apply.
9601  */
9602 static void cpu_cgroup_fork(struct task_struct *task)
9603 {
9604 	struct rq_flags rf;
9605 	struct rq *rq;
9606 
9607 	rq = task_rq_lock(task, &rf);
9608 
9609 	update_rq_clock(rq);
9610 	sched_change_group(task, TASK_SET_GROUP);
9611 
9612 	task_rq_unlock(rq, task, &rf);
9613 }
9614 
9615 static int cpu_cgroup_can_attach(struct cgroup_taskset *tset)
9616 {
9617 	struct task_struct *task;
9618 	struct cgroup_subsys_state *css;
9619 	int ret = 0;
9620 
9621 	cgroup_taskset_for_each(task, css, tset) {
9622 #ifdef CONFIG_RT_GROUP_SCHED
9623 		if (!sched_rt_can_attach(css_tg(css), task))
9624 			return -EINVAL;
9625 #endif
9626 		/*
9627 		 * Serialize against wake_up_new_task() such that if it's
9628 		 * running, we're sure to observe its full state.
9629 		 */
9630 		raw_spin_lock_irq(&task->pi_lock);
9631 		/*
9632 		 * Avoid calling sched_move_task() before wake_up_new_task()
9633 		 * has happened. This would lead to problems with PELT, due to
9634 		 * move wanting to detach+attach while we're not attached yet.
9635 		 */
9636 		if (READ_ONCE(task->__state) == TASK_NEW)
9637 			ret = -EINVAL;
9638 		raw_spin_unlock_irq(&task->pi_lock);
9639 
9640 		if (ret)
9641 			break;
9642 	}
9643 	return ret;
9644 }
9645 
9646 static void cpu_cgroup_attach(struct cgroup_taskset *tset)
9647 {
9648 	struct task_struct *task;
9649 	struct cgroup_subsys_state *css;
9650 
9651 	cgroup_taskset_for_each(task, css, tset)
9652 		sched_move_task(task);
9653 }
9654 
9655 #ifdef CONFIG_UCLAMP_TASK_GROUP
9656 static void cpu_util_update_eff(struct cgroup_subsys_state *css)
9657 {
9658 	struct cgroup_subsys_state *top_css = css;
9659 	struct uclamp_se *uc_parent = NULL;
9660 	struct uclamp_se *uc_se = NULL;
9661 	unsigned int eff[UCLAMP_CNT];
9662 	enum uclamp_id clamp_id;
9663 	unsigned int clamps;
9664 
9665 	lockdep_assert_held(&uclamp_mutex);
9666 	SCHED_WARN_ON(!rcu_read_lock_held());
9667 
9668 	css_for_each_descendant_pre(css, top_css) {
9669 		uc_parent = css_tg(css)->parent
9670 			? css_tg(css)->parent->uclamp : NULL;
9671 
9672 		for_each_clamp_id(clamp_id) {
9673 			/* Assume effective clamps matches requested clamps */
9674 			eff[clamp_id] = css_tg(css)->uclamp_req[clamp_id].value;
9675 			/* Cap effective clamps with parent's effective clamps */
9676 			if (uc_parent &&
9677 			    eff[clamp_id] > uc_parent[clamp_id].value) {
9678 				eff[clamp_id] = uc_parent[clamp_id].value;
9679 			}
9680 		}
9681 		/* Ensure protection is always capped by limit */
9682 		eff[UCLAMP_MIN] = min(eff[UCLAMP_MIN], eff[UCLAMP_MAX]);
9683 
9684 		/* Propagate most restrictive effective clamps */
9685 		clamps = 0x0;
9686 		uc_se = css_tg(css)->uclamp;
9687 		for_each_clamp_id(clamp_id) {
9688 			if (eff[clamp_id] == uc_se[clamp_id].value)
9689 				continue;
9690 			uc_se[clamp_id].value = eff[clamp_id];
9691 			uc_se[clamp_id].bucket_id = uclamp_bucket_id(eff[clamp_id]);
9692 			clamps |= (0x1 << clamp_id);
9693 		}
9694 		if (!clamps) {
9695 			css = css_rightmost_descendant(css);
9696 			continue;
9697 		}
9698 
9699 		/* Immediately update descendants RUNNABLE tasks */
9700 		uclamp_update_active_tasks(css);
9701 	}
9702 }
9703 
9704 /*
9705  * Integer 10^N with a given N exponent by casting to integer the literal "1eN"
9706  * C expression. Since there is no way to convert a macro argument (N) into a
9707  * character constant, use two levels of macros.
9708  */
9709 #define _POW10(exp) ((unsigned int)1e##exp)
9710 #define POW10(exp) _POW10(exp)
9711 
9712 struct uclamp_request {
9713 #define UCLAMP_PERCENT_SHIFT	2
9714 #define UCLAMP_PERCENT_SCALE	(100 * POW10(UCLAMP_PERCENT_SHIFT))
9715 	s64 percent;
9716 	u64 util;
9717 	int ret;
9718 };
9719 
9720 static inline struct uclamp_request
9721 capacity_from_percent(char *buf)
9722 {
9723 	struct uclamp_request req = {
9724 		.percent = UCLAMP_PERCENT_SCALE,
9725 		.util = SCHED_CAPACITY_SCALE,
9726 		.ret = 0,
9727 	};
9728 
9729 	buf = strim(buf);
9730 	if (strcmp(buf, "max")) {
9731 		req.ret = cgroup_parse_float(buf, UCLAMP_PERCENT_SHIFT,
9732 					     &req.percent);
9733 		if (req.ret)
9734 			return req;
9735 		if ((u64)req.percent > UCLAMP_PERCENT_SCALE) {
9736 			req.ret = -ERANGE;
9737 			return req;
9738 		}
9739 
9740 		req.util = req.percent << SCHED_CAPACITY_SHIFT;
9741 		req.util = DIV_ROUND_CLOSEST_ULL(req.util, UCLAMP_PERCENT_SCALE);
9742 	}
9743 
9744 	return req;
9745 }
9746 
9747 static ssize_t cpu_uclamp_write(struct kernfs_open_file *of, char *buf,
9748 				size_t nbytes, loff_t off,
9749 				enum uclamp_id clamp_id)
9750 {
9751 	struct uclamp_request req;
9752 	struct task_group *tg;
9753 
9754 	req = capacity_from_percent(buf);
9755 	if (req.ret)
9756 		return req.ret;
9757 
9758 	static_branch_enable(&sched_uclamp_used);
9759 
9760 	mutex_lock(&uclamp_mutex);
9761 	rcu_read_lock();
9762 
9763 	tg = css_tg(of_css(of));
9764 	if (tg->uclamp_req[clamp_id].value != req.util)
9765 		uclamp_se_set(&tg->uclamp_req[clamp_id], req.util, false);
9766 
9767 	/*
9768 	 * Because of not recoverable conversion rounding we keep track of the
9769 	 * exact requested value
9770 	 */
9771 	tg->uclamp_pct[clamp_id] = req.percent;
9772 
9773 	/* Update effective clamps to track the most restrictive value */
9774 	cpu_util_update_eff(of_css(of));
9775 
9776 	rcu_read_unlock();
9777 	mutex_unlock(&uclamp_mutex);
9778 
9779 	return nbytes;
9780 }
9781 
9782 static ssize_t cpu_uclamp_min_write(struct kernfs_open_file *of,
9783 				    char *buf, size_t nbytes,
9784 				    loff_t off)
9785 {
9786 	return cpu_uclamp_write(of, buf, nbytes, off, UCLAMP_MIN);
9787 }
9788 
9789 static ssize_t cpu_uclamp_max_write(struct kernfs_open_file *of,
9790 				    char *buf, size_t nbytes,
9791 				    loff_t off)
9792 {
9793 	return cpu_uclamp_write(of, buf, nbytes, off, UCLAMP_MAX);
9794 }
9795 
9796 static inline void cpu_uclamp_print(struct seq_file *sf,
9797 				    enum uclamp_id clamp_id)
9798 {
9799 	struct task_group *tg;
9800 	u64 util_clamp;
9801 	u64 percent;
9802 	u32 rem;
9803 
9804 	rcu_read_lock();
9805 	tg = css_tg(seq_css(sf));
9806 	util_clamp = tg->uclamp_req[clamp_id].value;
9807 	rcu_read_unlock();
9808 
9809 	if (util_clamp == SCHED_CAPACITY_SCALE) {
9810 		seq_puts(sf, "max\n");
9811 		return;
9812 	}
9813 
9814 	percent = tg->uclamp_pct[clamp_id];
9815 	percent = div_u64_rem(percent, POW10(UCLAMP_PERCENT_SHIFT), &rem);
9816 	seq_printf(sf, "%llu.%0*u\n", percent, UCLAMP_PERCENT_SHIFT, rem);
9817 }
9818 
9819 static int cpu_uclamp_min_show(struct seq_file *sf, void *v)
9820 {
9821 	cpu_uclamp_print(sf, UCLAMP_MIN);
9822 	return 0;
9823 }
9824 
9825 static int cpu_uclamp_max_show(struct seq_file *sf, void *v)
9826 {
9827 	cpu_uclamp_print(sf, UCLAMP_MAX);
9828 	return 0;
9829 }
9830 #endif /* CONFIG_UCLAMP_TASK_GROUP */
9831 
9832 #ifdef CONFIG_FAIR_GROUP_SCHED
9833 static int cpu_shares_write_u64(struct cgroup_subsys_state *css,
9834 				struct cftype *cftype, u64 shareval)
9835 {
9836 	if (shareval > scale_load_down(ULONG_MAX))
9837 		shareval = MAX_SHARES;
9838 	return sched_group_set_shares(css_tg(css), scale_load(shareval));
9839 }
9840 
9841 static u64 cpu_shares_read_u64(struct cgroup_subsys_state *css,
9842 			       struct cftype *cft)
9843 {
9844 	struct task_group *tg = css_tg(css);
9845 
9846 	return (u64) scale_load_down(tg->shares);
9847 }
9848 
9849 #ifdef CONFIG_CFS_BANDWIDTH
9850 static DEFINE_MUTEX(cfs_constraints_mutex);
9851 
9852 const u64 max_cfs_quota_period = 1 * NSEC_PER_SEC; /* 1s */
9853 static const u64 min_cfs_quota_period = 1 * NSEC_PER_MSEC; /* 1ms */
9854 /* More than 203 days if BW_SHIFT equals 20. */
9855 static const u64 max_cfs_runtime = MAX_BW * NSEC_PER_USEC;
9856 
9857 static int __cfs_schedulable(struct task_group *tg, u64 period, u64 runtime);
9858 
9859 static int tg_set_cfs_bandwidth(struct task_group *tg, u64 period, u64 quota,
9860 				u64 burst)
9861 {
9862 	int i, ret = 0, runtime_enabled, runtime_was_enabled;
9863 	struct cfs_bandwidth *cfs_b = &tg->cfs_bandwidth;
9864 
9865 	if (tg == &root_task_group)
9866 		return -EINVAL;
9867 
9868 	/*
9869 	 * Ensure we have at some amount of bandwidth every period.  This is
9870 	 * to prevent reaching a state of large arrears when throttled via
9871 	 * entity_tick() resulting in prolonged exit starvation.
9872 	 */
9873 	if (quota < min_cfs_quota_period || period < min_cfs_quota_period)
9874 		return -EINVAL;
9875 
9876 	/*
9877 	 * Likewise, bound things on the other side by preventing insane quota
9878 	 * periods.  This also allows us to normalize in computing quota
9879 	 * feasibility.
9880 	 */
9881 	if (period > max_cfs_quota_period)
9882 		return -EINVAL;
9883 
9884 	/*
9885 	 * Bound quota to defend quota against overflow during bandwidth shift.
9886 	 */
9887 	if (quota != RUNTIME_INF && quota > max_cfs_runtime)
9888 		return -EINVAL;
9889 
9890 	if (quota != RUNTIME_INF && (burst > quota ||
9891 				     burst + quota > max_cfs_runtime))
9892 		return -EINVAL;
9893 
9894 	/*
9895 	 * Prevent race between setting of cfs_rq->runtime_enabled and
9896 	 * unthrottle_offline_cfs_rqs().
9897 	 */
9898 	get_online_cpus();
9899 	mutex_lock(&cfs_constraints_mutex);
9900 	ret = __cfs_schedulable(tg, period, quota);
9901 	if (ret)
9902 		goto out_unlock;
9903 
9904 	runtime_enabled = quota != RUNTIME_INF;
9905 	runtime_was_enabled = cfs_b->quota != RUNTIME_INF;
9906 	/*
9907 	 * If we need to toggle cfs_bandwidth_used, off->on must occur
9908 	 * before making related changes, and on->off must occur afterwards
9909 	 */
9910 	if (runtime_enabled && !runtime_was_enabled)
9911 		cfs_bandwidth_usage_inc();
9912 	raw_spin_lock_irq(&cfs_b->lock);
9913 	cfs_b->period = ns_to_ktime(period);
9914 	cfs_b->quota = quota;
9915 	cfs_b->burst = burst;
9916 
9917 	__refill_cfs_bandwidth_runtime(cfs_b);
9918 
9919 	/* Restart the period timer (if active) to handle new period expiry: */
9920 	if (runtime_enabled)
9921 		start_cfs_bandwidth(cfs_b);
9922 
9923 	raw_spin_unlock_irq(&cfs_b->lock);
9924 
9925 	for_each_online_cpu(i) {
9926 		struct cfs_rq *cfs_rq = tg->cfs_rq[i];
9927 		struct rq *rq = cfs_rq->rq;
9928 		struct rq_flags rf;
9929 
9930 		rq_lock_irq(rq, &rf);
9931 		cfs_rq->runtime_enabled = runtime_enabled;
9932 		cfs_rq->runtime_remaining = 0;
9933 
9934 		if (cfs_rq->throttled)
9935 			unthrottle_cfs_rq(cfs_rq);
9936 		rq_unlock_irq(rq, &rf);
9937 	}
9938 	if (runtime_was_enabled && !runtime_enabled)
9939 		cfs_bandwidth_usage_dec();
9940 out_unlock:
9941 	mutex_unlock(&cfs_constraints_mutex);
9942 	put_online_cpus();
9943 
9944 	return ret;
9945 }
9946 
9947 static int tg_set_cfs_quota(struct task_group *tg, long cfs_quota_us)
9948 {
9949 	u64 quota, period, burst;
9950 
9951 	period = ktime_to_ns(tg->cfs_bandwidth.period);
9952 	burst = tg->cfs_bandwidth.burst;
9953 	if (cfs_quota_us < 0)
9954 		quota = RUNTIME_INF;
9955 	else if ((u64)cfs_quota_us <= U64_MAX / NSEC_PER_USEC)
9956 		quota = (u64)cfs_quota_us * NSEC_PER_USEC;
9957 	else
9958 		return -EINVAL;
9959 
9960 	return tg_set_cfs_bandwidth(tg, period, quota, burst);
9961 }
9962 
9963 static long tg_get_cfs_quota(struct task_group *tg)
9964 {
9965 	u64 quota_us;
9966 
9967 	if (tg->cfs_bandwidth.quota == RUNTIME_INF)
9968 		return -1;
9969 
9970 	quota_us = tg->cfs_bandwidth.quota;
9971 	do_div(quota_us, NSEC_PER_USEC);
9972 
9973 	return quota_us;
9974 }
9975 
9976 static int tg_set_cfs_period(struct task_group *tg, long cfs_period_us)
9977 {
9978 	u64 quota, period, burst;
9979 
9980 	if ((u64)cfs_period_us > U64_MAX / NSEC_PER_USEC)
9981 		return -EINVAL;
9982 
9983 	period = (u64)cfs_period_us * NSEC_PER_USEC;
9984 	quota = tg->cfs_bandwidth.quota;
9985 	burst = tg->cfs_bandwidth.burst;
9986 
9987 	return tg_set_cfs_bandwidth(tg, period, quota, burst);
9988 }
9989 
9990 static long tg_get_cfs_period(struct task_group *tg)
9991 {
9992 	u64 cfs_period_us;
9993 
9994 	cfs_period_us = ktime_to_ns(tg->cfs_bandwidth.period);
9995 	do_div(cfs_period_us, NSEC_PER_USEC);
9996 
9997 	return cfs_period_us;
9998 }
9999 
10000 static int tg_set_cfs_burst(struct task_group *tg, long cfs_burst_us)
10001 {
10002 	u64 quota, period, burst;
10003 
10004 	if ((u64)cfs_burst_us > U64_MAX / NSEC_PER_USEC)
10005 		return -EINVAL;
10006 
10007 	burst = (u64)cfs_burst_us * NSEC_PER_USEC;
10008 	period = ktime_to_ns(tg->cfs_bandwidth.period);
10009 	quota = tg->cfs_bandwidth.quota;
10010 
10011 	return tg_set_cfs_bandwidth(tg, period, quota, burst);
10012 }
10013 
10014 static long tg_get_cfs_burst(struct task_group *tg)
10015 {
10016 	u64 burst_us;
10017 
10018 	burst_us = tg->cfs_bandwidth.burst;
10019 	do_div(burst_us, NSEC_PER_USEC);
10020 
10021 	return burst_us;
10022 }
10023 
10024 static s64 cpu_cfs_quota_read_s64(struct cgroup_subsys_state *css,
10025 				  struct cftype *cft)
10026 {
10027 	return tg_get_cfs_quota(css_tg(css));
10028 }
10029 
10030 static int cpu_cfs_quota_write_s64(struct cgroup_subsys_state *css,
10031 				   struct cftype *cftype, s64 cfs_quota_us)
10032 {
10033 	return tg_set_cfs_quota(css_tg(css), cfs_quota_us);
10034 }
10035 
10036 static u64 cpu_cfs_period_read_u64(struct cgroup_subsys_state *css,
10037 				   struct cftype *cft)
10038 {
10039 	return tg_get_cfs_period(css_tg(css));
10040 }
10041 
10042 static int cpu_cfs_period_write_u64(struct cgroup_subsys_state *css,
10043 				    struct cftype *cftype, u64 cfs_period_us)
10044 {
10045 	return tg_set_cfs_period(css_tg(css), cfs_period_us);
10046 }
10047 
10048 static u64 cpu_cfs_burst_read_u64(struct cgroup_subsys_state *css,
10049 				  struct cftype *cft)
10050 {
10051 	return tg_get_cfs_burst(css_tg(css));
10052 }
10053 
10054 static int cpu_cfs_burst_write_u64(struct cgroup_subsys_state *css,
10055 				   struct cftype *cftype, u64 cfs_burst_us)
10056 {
10057 	return tg_set_cfs_burst(css_tg(css), cfs_burst_us);
10058 }
10059 
10060 struct cfs_schedulable_data {
10061 	struct task_group *tg;
10062 	u64 period, quota;
10063 };
10064 
10065 /*
10066  * normalize group quota/period to be quota/max_period
10067  * note: units are usecs
10068  */
10069 static u64 normalize_cfs_quota(struct task_group *tg,
10070 			       struct cfs_schedulable_data *d)
10071 {
10072 	u64 quota, period;
10073 
10074 	if (tg == d->tg) {
10075 		period = d->period;
10076 		quota = d->quota;
10077 	} else {
10078 		period = tg_get_cfs_period(tg);
10079 		quota = tg_get_cfs_quota(tg);
10080 	}
10081 
10082 	/* note: these should typically be equivalent */
10083 	if (quota == RUNTIME_INF || quota == -1)
10084 		return RUNTIME_INF;
10085 
10086 	return to_ratio(period, quota);
10087 }
10088 
10089 static int tg_cfs_schedulable_down(struct task_group *tg, void *data)
10090 {
10091 	struct cfs_schedulable_data *d = data;
10092 	struct cfs_bandwidth *cfs_b = &tg->cfs_bandwidth;
10093 	s64 quota = 0, parent_quota = -1;
10094 
10095 	if (!tg->parent) {
10096 		quota = RUNTIME_INF;
10097 	} else {
10098 		struct cfs_bandwidth *parent_b = &tg->parent->cfs_bandwidth;
10099 
10100 		quota = normalize_cfs_quota(tg, d);
10101 		parent_quota = parent_b->hierarchical_quota;
10102 
10103 		/*
10104 		 * Ensure max(child_quota) <= parent_quota.  On cgroup2,
10105 		 * always take the min.  On cgroup1, only inherit when no
10106 		 * limit is set:
10107 		 */
10108 		if (cgroup_subsys_on_dfl(cpu_cgrp_subsys)) {
10109 			quota = min(quota, parent_quota);
10110 		} else {
10111 			if (quota == RUNTIME_INF)
10112 				quota = parent_quota;
10113 			else if (parent_quota != RUNTIME_INF && quota > parent_quota)
10114 				return -EINVAL;
10115 		}
10116 	}
10117 	cfs_b->hierarchical_quota = quota;
10118 
10119 	return 0;
10120 }
10121 
10122 static int __cfs_schedulable(struct task_group *tg, u64 period, u64 quota)
10123 {
10124 	int ret;
10125 	struct cfs_schedulable_data data = {
10126 		.tg = tg,
10127 		.period = period,
10128 		.quota = quota,
10129 	};
10130 
10131 	if (quota != RUNTIME_INF) {
10132 		do_div(data.period, NSEC_PER_USEC);
10133 		do_div(data.quota, NSEC_PER_USEC);
10134 	}
10135 
10136 	rcu_read_lock();
10137 	ret = walk_tg_tree(tg_cfs_schedulable_down, tg_nop, &data);
10138 	rcu_read_unlock();
10139 
10140 	return ret;
10141 }
10142 
10143 static int cpu_cfs_stat_show(struct seq_file *sf, void *v)
10144 {
10145 	struct task_group *tg = css_tg(seq_css(sf));
10146 	struct cfs_bandwidth *cfs_b = &tg->cfs_bandwidth;
10147 
10148 	seq_printf(sf, "nr_periods %d\n", cfs_b->nr_periods);
10149 	seq_printf(sf, "nr_throttled %d\n", cfs_b->nr_throttled);
10150 	seq_printf(sf, "throttled_time %llu\n", cfs_b->throttled_time);
10151 
10152 	if (schedstat_enabled() && tg != &root_task_group) {
10153 		u64 ws = 0;
10154 		int i;
10155 
10156 		for_each_possible_cpu(i)
10157 			ws += schedstat_val(tg->se[i]->statistics.wait_sum);
10158 
10159 		seq_printf(sf, "wait_sum %llu\n", ws);
10160 	}
10161 
10162 	return 0;
10163 }
10164 #endif /* CONFIG_CFS_BANDWIDTH */
10165 #endif /* CONFIG_FAIR_GROUP_SCHED */
10166 
10167 #ifdef CONFIG_RT_GROUP_SCHED
10168 static int cpu_rt_runtime_write(struct cgroup_subsys_state *css,
10169 				struct cftype *cft, s64 val)
10170 {
10171 	return sched_group_set_rt_runtime(css_tg(css), val);
10172 }
10173 
10174 static s64 cpu_rt_runtime_read(struct cgroup_subsys_state *css,
10175 			       struct cftype *cft)
10176 {
10177 	return sched_group_rt_runtime(css_tg(css));
10178 }
10179 
10180 static int cpu_rt_period_write_uint(struct cgroup_subsys_state *css,
10181 				    struct cftype *cftype, u64 rt_period_us)
10182 {
10183 	return sched_group_set_rt_period(css_tg(css), rt_period_us);
10184 }
10185 
10186 static u64 cpu_rt_period_read_uint(struct cgroup_subsys_state *css,
10187 				   struct cftype *cft)
10188 {
10189 	return sched_group_rt_period(css_tg(css));
10190 }
10191 #endif /* CONFIG_RT_GROUP_SCHED */
10192 
10193 static struct cftype cpu_legacy_files[] = {
10194 #ifdef CONFIG_FAIR_GROUP_SCHED
10195 	{
10196 		.name = "shares",
10197 		.read_u64 = cpu_shares_read_u64,
10198 		.write_u64 = cpu_shares_write_u64,
10199 	},
10200 #endif
10201 #ifdef CONFIG_CFS_BANDWIDTH
10202 	{
10203 		.name = "cfs_quota_us",
10204 		.read_s64 = cpu_cfs_quota_read_s64,
10205 		.write_s64 = cpu_cfs_quota_write_s64,
10206 	},
10207 	{
10208 		.name = "cfs_period_us",
10209 		.read_u64 = cpu_cfs_period_read_u64,
10210 		.write_u64 = cpu_cfs_period_write_u64,
10211 	},
10212 	{
10213 		.name = "cfs_burst_us",
10214 		.read_u64 = cpu_cfs_burst_read_u64,
10215 		.write_u64 = cpu_cfs_burst_write_u64,
10216 	},
10217 	{
10218 		.name = "stat",
10219 		.seq_show = cpu_cfs_stat_show,
10220 	},
10221 #endif
10222 #ifdef CONFIG_RT_GROUP_SCHED
10223 	{
10224 		.name = "rt_runtime_us",
10225 		.read_s64 = cpu_rt_runtime_read,
10226 		.write_s64 = cpu_rt_runtime_write,
10227 	},
10228 	{
10229 		.name = "rt_period_us",
10230 		.read_u64 = cpu_rt_period_read_uint,
10231 		.write_u64 = cpu_rt_period_write_uint,
10232 	},
10233 #endif
10234 #ifdef CONFIG_UCLAMP_TASK_GROUP
10235 	{
10236 		.name = "uclamp.min",
10237 		.flags = CFTYPE_NOT_ON_ROOT,
10238 		.seq_show = cpu_uclamp_min_show,
10239 		.write = cpu_uclamp_min_write,
10240 	},
10241 	{
10242 		.name = "uclamp.max",
10243 		.flags = CFTYPE_NOT_ON_ROOT,
10244 		.seq_show = cpu_uclamp_max_show,
10245 		.write = cpu_uclamp_max_write,
10246 	},
10247 #endif
10248 	{ }	/* Terminate */
10249 };
10250 
10251 static int cpu_extra_stat_show(struct seq_file *sf,
10252 			       struct cgroup_subsys_state *css)
10253 {
10254 #ifdef CONFIG_CFS_BANDWIDTH
10255 	{
10256 		struct task_group *tg = css_tg(css);
10257 		struct cfs_bandwidth *cfs_b = &tg->cfs_bandwidth;
10258 		u64 throttled_usec;
10259 
10260 		throttled_usec = cfs_b->throttled_time;
10261 		do_div(throttled_usec, NSEC_PER_USEC);
10262 
10263 		seq_printf(sf, "nr_periods %d\n"
10264 			   "nr_throttled %d\n"
10265 			   "throttled_usec %llu\n",
10266 			   cfs_b->nr_periods, cfs_b->nr_throttled,
10267 			   throttled_usec);
10268 	}
10269 #endif
10270 	return 0;
10271 }
10272 
10273 #ifdef CONFIG_FAIR_GROUP_SCHED
10274 static u64 cpu_weight_read_u64(struct cgroup_subsys_state *css,
10275 			       struct cftype *cft)
10276 {
10277 	struct task_group *tg = css_tg(css);
10278 	u64 weight = scale_load_down(tg->shares);
10279 
10280 	return DIV_ROUND_CLOSEST_ULL(weight * CGROUP_WEIGHT_DFL, 1024);
10281 }
10282 
10283 static int cpu_weight_write_u64(struct cgroup_subsys_state *css,
10284 				struct cftype *cft, u64 weight)
10285 {
10286 	/*
10287 	 * cgroup weight knobs should use the common MIN, DFL and MAX
10288 	 * values which are 1, 100 and 10000 respectively.  While it loses
10289 	 * a bit of range on both ends, it maps pretty well onto the shares
10290 	 * value used by scheduler and the round-trip conversions preserve
10291 	 * the original value over the entire range.
10292 	 */
10293 	if (weight < CGROUP_WEIGHT_MIN || weight > CGROUP_WEIGHT_MAX)
10294 		return -ERANGE;
10295 
10296 	weight = DIV_ROUND_CLOSEST_ULL(weight * 1024, CGROUP_WEIGHT_DFL);
10297 
10298 	return sched_group_set_shares(css_tg(css), scale_load(weight));
10299 }
10300 
10301 static s64 cpu_weight_nice_read_s64(struct cgroup_subsys_state *css,
10302 				    struct cftype *cft)
10303 {
10304 	unsigned long weight = scale_load_down(css_tg(css)->shares);
10305 	int last_delta = INT_MAX;
10306 	int prio, delta;
10307 
10308 	/* find the closest nice value to the current weight */
10309 	for (prio = 0; prio < ARRAY_SIZE(sched_prio_to_weight); prio++) {
10310 		delta = abs(sched_prio_to_weight[prio] - weight);
10311 		if (delta >= last_delta)
10312 			break;
10313 		last_delta = delta;
10314 	}
10315 
10316 	return PRIO_TO_NICE(prio - 1 + MAX_RT_PRIO);
10317 }
10318 
10319 static int cpu_weight_nice_write_s64(struct cgroup_subsys_state *css,
10320 				     struct cftype *cft, s64 nice)
10321 {
10322 	unsigned long weight;
10323 	int idx;
10324 
10325 	if (nice < MIN_NICE || nice > MAX_NICE)
10326 		return -ERANGE;
10327 
10328 	idx = NICE_TO_PRIO(nice) - MAX_RT_PRIO;
10329 	idx = array_index_nospec(idx, 40);
10330 	weight = sched_prio_to_weight[idx];
10331 
10332 	return sched_group_set_shares(css_tg(css), scale_load(weight));
10333 }
10334 #endif
10335 
10336 static void __maybe_unused cpu_period_quota_print(struct seq_file *sf,
10337 						  long period, long quota)
10338 {
10339 	if (quota < 0)
10340 		seq_puts(sf, "max");
10341 	else
10342 		seq_printf(sf, "%ld", quota);
10343 
10344 	seq_printf(sf, " %ld\n", period);
10345 }
10346 
10347 /* caller should put the current value in *@periodp before calling */
10348 static int __maybe_unused cpu_period_quota_parse(char *buf,
10349 						 u64 *periodp, u64 *quotap)
10350 {
10351 	char tok[21];	/* U64_MAX */
10352 
10353 	if (sscanf(buf, "%20s %llu", tok, periodp) < 1)
10354 		return -EINVAL;
10355 
10356 	*periodp *= NSEC_PER_USEC;
10357 
10358 	if (sscanf(tok, "%llu", quotap))
10359 		*quotap *= NSEC_PER_USEC;
10360 	else if (!strcmp(tok, "max"))
10361 		*quotap = RUNTIME_INF;
10362 	else
10363 		return -EINVAL;
10364 
10365 	return 0;
10366 }
10367 
10368 #ifdef CONFIG_CFS_BANDWIDTH
10369 static int cpu_max_show(struct seq_file *sf, void *v)
10370 {
10371 	struct task_group *tg = css_tg(seq_css(sf));
10372 
10373 	cpu_period_quota_print(sf, tg_get_cfs_period(tg), tg_get_cfs_quota(tg));
10374 	return 0;
10375 }
10376 
10377 static ssize_t cpu_max_write(struct kernfs_open_file *of,
10378 			     char *buf, size_t nbytes, loff_t off)
10379 {
10380 	struct task_group *tg = css_tg(of_css(of));
10381 	u64 period = tg_get_cfs_period(tg);
10382 	u64 burst = tg_get_cfs_burst(tg);
10383 	u64 quota;
10384 	int ret;
10385 
10386 	ret = cpu_period_quota_parse(buf, &period, &quota);
10387 	if (!ret)
10388 		ret = tg_set_cfs_bandwidth(tg, period, quota, burst);
10389 	return ret ?: nbytes;
10390 }
10391 #endif
10392 
10393 static struct cftype cpu_files[] = {
10394 #ifdef CONFIG_FAIR_GROUP_SCHED
10395 	{
10396 		.name = "weight",
10397 		.flags = CFTYPE_NOT_ON_ROOT,
10398 		.read_u64 = cpu_weight_read_u64,
10399 		.write_u64 = cpu_weight_write_u64,
10400 	},
10401 	{
10402 		.name = "weight.nice",
10403 		.flags = CFTYPE_NOT_ON_ROOT,
10404 		.read_s64 = cpu_weight_nice_read_s64,
10405 		.write_s64 = cpu_weight_nice_write_s64,
10406 	},
10407 #endif
10408 #ifdef CONFIG_CFS_BANDWIDTH
10409 	{
10410 		.name = "max",
10411 		.flags = CFTYPE_NOT_ON_ROOT,
10412 		.seq_show = cpu_max_show,
10413 		.write = cpu_max_write,
10414 	},
10415 	{
10416 		.name = "max.burst",
10417 		.flags = CFTYPE_NOT_ON_ROOT,
10418 		.read_u64 = cpu_cfs_burst_read_u64,
10419 		.write_u64 = cpu_cfs_burst_write_u64,
10420 	},
10421 #endif
10422 #ifdef CONFIG_UCLAMP_TASK_GROUP
10423 	{
10424 		.name = "uclamp.min",
10425 		.flags = CFTYPE_NOT_ON_ROOT,
10426 		.seq_show = cpu_uclamp_min_show,
10427 		.write = cpu_uclamp_min_write,
10428 	},
10429 	{
10430 		.name = "uclamp.max",
10431 		.flags = CFTYPE_NOT_ON_ROOT,
10432 		.seq_show = cpu_uclamp_max_show,
10433 		.write = cpu_uclamp_max_write,
10434 	},
10435 #endif
10436 	{ }	/* terminate */
10437 };
10438 
10439 struct cgroup_subsys cpu_cgrp_subsys = {
10440 	.css_alloc	= cpu_cgroup_css_alloc,
10441 	.css_online	= cpu_cgroup_css_online,
10442 	.css_released	= cpu_cgroup_css_released,
10443 	.css_free	= cpu_cgroup_css_free,
10444 	.css_extra_stat_show = cpu_extra_stat_show,
10445 	.fork		= cpu_cgroup_fork,
10446 	.can_attach	= cpu_cgroup_can_attach,
10447 	.attach		= cpu_cgroup_attach,
10448 	.legacy_cftypes	= cpu_legacy_files,
10449 	.dfl_cftypes	= cpu_files,
10450 	.early_init	= true,
10451 	.threaded	= true,
10452 };
10453 
10454 #endif	/* CONFIG_CGROUP_SCHED */
10455 
10456 void dump_cpu_task(int cpu)
10457 {
10458 	pr_info("Task dump for CPU %d:\n", cpu);
10459 	sched_show_task(cpu_curr(cpu));
10460 }
10461 
10462 /*
10463  * Nice levels are multiplicative, with a gentle 10% change for every
10464  * nice level changed. I.e. when a CPU-bound task goes from nice 0 to
10465  * nice 1, it will get ~10% less CPU time than another CPU-bound task
10466  * that remained on nice 0.
10467  *
10468  * The "10% effect" is relative and cumulative: from _any_ nice level,
10469  * if you go up 1 level, it's -10% CPU usage, if you go down 1 level
10470  * it's +10% CPU usage. (to achieve that we use a multiplier of 1.25.
10471  * If a task goes up by ~10% and another task goes down by ~10% then
10472  * the relative distance between them is ~25%.)
10473  */
10474 const int sched_prio_to_weight[40] = {
10475  /* -20 */     88761,     71755,     56483,     46273,     36291,
10476  /* -15 */     29154,     23254,     18705,     14949,     11916,
10477  /* -10 */      9548,      7620,      6100,      4904,      3906,
10478  /*  -5 */      3121,      2501,      1991,      1586,      1277,
10479  /*   0 */      1024,       820,       655,       526,       423,
10480  /*   5 */       335,       272,       215,       172,       137,
10481  /*  10 */       110,        87,        70,        56,        45,
10482  /*  15 */        36,        29,        23,        18,        15,
10483 };
10484 
10485 /*
10486  * Inverse (2^32/x) values of the sched_prio_to_weight[] array, precalculated.
10487  *
10488  * In cases where the weight does not change often, we can use the
10489  * precalculated inverse to speed up arithmetics by turning divisions
10490  * into multiplications:
10491  */
10492 const u32 sched_prio_to_wmult[40] = {
10493  /* -20 */     48388,     59856,     76040,     92818,    118348,
10494  /* -15 */    147320,    184698,    229616,    287308,    360437,
10495  /* -10 */    449829,    563644,    704093,    875809,   1099582,
10496  /*  -5 */   1376151,   1717300,   2157191,   2708050,   3363326,
10497  /*   0 */   4194304,   5237765,   6557202,   8165337,  10153587,
10498  /*   5 */  12820798,  15790321,  19976592,  24970740,  31350126,
10499  /*  10 */  39045157,  49367440,  61356676,  76695844,  95443717,
10500  /*  15 */ 119304647, 148102320, 186737708, 238609294, 286331153,
10501 };
10502 
10503 void call_trace_sched_update_nr_running(struct rq *rq, int count)
10504 {
10505         trace_sched_update_nr_running_tp(rq, count);
10506 }
10507