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1 | /* | |
2 | * kernel/sched/core.c | |
3 | * | |
4 | * Core kernel scheduler code and related syscalls | |
5 | * | |
6 | * Copyright (C) 1991-2002 Linus Torvalds | |
7 | */ | |
8 | #include "sched.h" | |
9 | ||
10 | #include <asm/switch_to.h> | |
11 | #include <asm/tlb.h> | |
12 | ||
13 | #include "../workqueue_internal.h" | |
14 | #include "../smpboot.h" | |
15 | ||
16 | #define CREATE_TRACE_POINTS | |
17 | #include <trace/events/sched.h> | |
18 | ||
19 | DEFINE_PER_CPU_SHARED_ALIGNED(struct rq, runqueues); | |
20 | ||
21 | #if defined(CONFIG_SCHED_DEBUG) && defined(HAVE_JUMP_LABEL) | |
22 | /* | |
23 | * Debugging: various feature bits | |
24 | * | |
25 | * If SCHED_DEBUG is disabled, each compilation unit has its own copy of | |
26 | * sysctl_sched_features, defined in sched.h, to allow constants propagation | |
27 | * at compile time and compiler optimization based on features default. | |
28 | */ | |
29 | #define SCHED_FEAT(name, enabled) \ | |
30 | (1UL << __SCHED_FEAT_##name) * enabled | | |
31 | const_debug unsigned int sysctl_sched_features = | |
32 | #include "features.h" | |
33 | 0; | |
34 | #undef SCHED_FEAT | |
35 | #endif | |
36 | ||
37 | /* | |
38 | * Number of tasks to iterate in a single balance run. | |
39 | * Limited because this is done with IRQs disabled. | |
40 | */ | |
41 | const_debug unsigned int sysctl_sched_nr_migrate = 32; | |
42 | ||
43 | /* | |
44 | * period over which we average the RT time consumption, measured | |
45 | * in ms. | |
46 | * | |
47 | * default: 1s | |
48 | */ | |
49 | const_debug unsigned int sysctl_sched_time_avg = MSEC_PER_SEC; | |
50 | ||
51 | /* | |
52 | * period over which we measure -rt task CPU usage in us. | |
53 | * default: 1s | |
54 | */ | |
55 | unsigned int sysctl_sched_rt_period = 1000000; | |
56 | ||
57 | __read_mostly int scheduler_running; | |
58 | ||
59 | /* | |
60 | * part of the period that we allow rt tasks to run in us. | |
61 | * default: 0.95s | |
62 | */ | |
63 | int sysctl_sched_rt_runtime = 950000; | |
64 | ||
65 | /* | |
66 | * __task_rq_lock - lock the rq @p resides on. | |
67 | */ | |
68 | struct rq *__task_rq_lock(struct task_struct *p, struct rq_flags *rf) | |
69 | __acquires(rq->lock) | |
70 | { | |
71 | struct rq *rq; | |
72 | ||
73 | lockdep_assert_held(&p->pi_lock); | |
74 | ||
75 | for (;;) { | |
76 | rq = task_rq(p); | |
77 | raw_spin_lock(&rq->lock); | |
78 | if (likely(rq == task_rq(p) && !task_on_rq_migrating(p))) { | |
79 | rq_pin_lock(rq, rf); | |
80 | return rq; | |
81 | } | |
82 | raw_spin_unlock(&rq->lock); | |
83 | ||
84 | while (unlikely(task_on_rq_migrating(p))) | |
85 | cpu_relax(); | |
86 | } | |
87 | } | |
88 | ||
89 | /* | |
90 | * task_rq_lock - lock p->pi_lock and lock the rq @p resides on. | |
91 | */ | |
92 | struct rq *task_rq_lock(struct task_struct *p, struct rq_flags *rf) | |
93 | __acquires(p->pi_lock) | |
94 | __acquires(rq->lock) | |
95 | { | |
96 | struct rq *rq; | |
97 | ||
98 | for (;;) { | |
99 | raw_spin_lock_irqsave(&p->pi_lock, rf->flags); | |
100 | rq = task_rq(p); | |
101 | raw_spin_lock(&rq->lock); | |
102 | /* | |
103 | * move_queued_task() task_rq_lock() | |
104 | * | |
105 | * ACQUIRE (rq->lock) | |
106 | * [S] ->on_rq = MIGRATING [L] rq = task_rq() | |
107 | * WMB (__set_task_cpu()) ACQUIRE (rq->lock); | |
108 | * [S] ->cpu = new_cpu [L] task_rq() | |
109 | * [L] ->on_rq | |
110 | * RELEASE (rq->lock) | |
111 | * | |
112 | * If we observe the old CPU in task_rq_lock, the acquire of | |
113 | * the old rq->lock will fully serialize against the stores. | |
114 | * | |
115 | * If we observe the new CPU in task_rq_lock, the acquire will | |
116 | * pair with the WMB to ensure we must then also see migrating. | |
117 | */ | |
118 | if (likely(rq == task_rq(p) && !task_on_rq_migrating(p))) { | |
119 | rq_pin_lock(rq, rf); | |
120 | return rq; | |
121 | } | |
122 | raw_spin_unlock(&rq->lock); | |
123 | raw_spin_unlock_irqrestore(&p->pi_lock, rf->flags); | |
124 | ||
125 | while (unlikely(task_on_rq_migrating(p))) | |
126 | cpu_relax(); | |
127 | } | |
128 | } | |
129 | ||
130 | /* | |
131 | * RQ-clock updating methods: | |
132 | */ | |
133 | ||
134 | static void update_rq_clock_task(struct rq *rq, s64 delta) | |
135 | { | |
136 | /* | |
137 | * In theory, the compile should just see 0 here, and optimize out the call | |
138 | * to sched_rt_avg_update. But I don't trust it... | |
139 | */ | |
140 | #if defined(CONFIG_IRQ_TIME_ACCOUNTING) || defined(CONFIG_PARAVIRT_TIME_ACCOUNTING) | |
141 | s64 steal = 0, irq_delta = 0; | |
142 | #endif | |
143 | #ifdef CONFIG_IRQ_TIME_ACCOUNTING | |
144 | irq_delta = irq_time_read(cpu_of(rq)) - rq->prev_irq_time; | |
145 | ||
146 | /* | |
147 | * Since irq_time is only updated on {soft,}irq_exit, we might run into | |
148 | * this case when a previous update_rq_clock() happened inside a | |
149 | * {soft,}irq region. | |
150 | * | |
151 | * When this happens, we stop ->clock_task and only update the | |
152 | * prev_irq_time stamp to account for the part that fit, so that a next | |
153 | * update will consume the rest. This ensures ->clock_task is | |
154 | * monotonic. | |
155 | * | |
156 | * It does however cause some slight miss-attribution of {soft,}irq | |
157 | * time, a more accurate solution would be to update the irq_time using | |
158 | * the current rq->clock timestamp, except that would require using | |
159 | * atomic ops. | |
160 | */ | |
161 | if (irq_delta > delta) | |
162 | irq_delta = delta; | |
163 | ||
164 | rq->prev_irq_time += irq_delta; | |
165 | delta -= irq_delta; | |
166 | #endif | |
167 | #ifdef CONFIG_PARAVIRT_TIME_ACCOUNTING | |
168 | if (static_key_false((¶virt_steal_rq_enabled))) { | |
169 | steal = paravirt_steal_clock(cpu_of(rq)); | |
170 | steal -= rq->prev_steal_time_rq; | |
171 | ||
172 | if (unlikely(steal > delta)) | |
173 | steal = delta; | |
174 | ||
175 | rq->prev_steal_time_rq += steal; | |
176 | delta -= steal; | |
177 | } | |
178 | #endif | |
179 | ||
180 | rq->clock_task += delta; | |
181 | ||
182 | #if defined(CONFIG_IRQ_TIME_ACCOUNTING) || defined(CONFIG_PARAVIRT_TIME_ACCOUNTING) | |
183 | if ((irq_delta + steal) && sched_feat(NONTASK_CAPACITY)) | |
184 | sched_rt_avg_update(rq, irq_delta + steal); | |
185 | #endif | |
186 | } | |
187 | ||
188 | void update_rq_clock(struct rq *rq) | |
189 | { | |
190 | s64 delta; | |
191 | ||
192 | lockdep_assert_held(&rq->lock); | |
193 | ||
194 | if (rq->clock_update_flags & RQCF_ACT_SKIP) | |
195 | return; | |
196 | ||
197 | #ifdef CONFIG_SCHED_DEBUG | |
198 | if (sched_feat(WARN_DOUBLE_CLOCK)) | |
199 | SCHED_WARN_ON(rq->clock_update_flags & RQCF_UPDATED); | |
200 | rq->clock_update_flags |= RQCF_UPDATED; | |
201 | #endif | |
202 | ||
203 | delta = sched_clock_cpu(cpu_of(rq)) - rq->clock; | |
204 | if (delta < 0) | |
205 | return; | |
206 | rq->clock += delta; | |
207 | update_rq_clock_task(rq, delta); | |
208 | } | |
209 | ||
210 | ||
211 | #ifdef CONFIG_SCHED_HRTICK | |
212 | /* | |
213 | * Use HR-timers to deliver accurate preemption points. | |
214 | */ | |
215 | ||
216 | static void hrtick_clear(struct rq *rq) | |
217 | { | |
218 | if (hrtimer_active(&rq->hrtick_timer)) | |
219 | hrtimer_cancel(&rq->hrtick_timer); | |
220 | } | |
221 | ||
222 | /* | |
223 | * High-resolution timer tick. | |
224 | * Runs from hardirq context with interrupts disabled. | |
225 | */ | |
226 | static enum hrtimer_restart hrtick(struct hrtimer *timer) | |
227 | { | |
228 | struct rq *rq = container_of(timer, struct rq, hrtick_timer); | |
229 | struct rq_flags rf; | |
230 | ||
231 | WARN_ON_ONCE(cpu_of(rq) != smp_processor_id()); | |
232 | ||
233 | rq_lock(rq, &rf); | |
234 | update_rq_clock(rq); | |
235 | rq->curr->sched_class->task_tick(rq, rq->curr, 1); | |
236 | rq_unlock(rq, &rf); | |
237 | ||
238 | return HRTIMER_NORESTART; | |
239 | } | |
240 | ||
241 | #ifdef CONFIG_SMP | |
242 | ||
243 | static void __hrtick_restart(struct rq *rq) | |
244 | { | |
245 | struct hrtimer *timer = &rq->hrtick_timer; | |
246 | ||
247 | hrtimer_start_expires(timer, HRTIMER_MODE_ABS_PINNED); | |
248 | } | |
249 | ||
250 | /* | |
251 | * called from hardirq (IPI) context | |
252 | */ | |
253 | static void __hrtick_start(void *arg) | |
254 | { | |
255 | struct rq *rq = arg; | |
256 | struct rq_flags rf; | |
257 | ||
258 | rq_lock(rq, &rf); | |
259 | __hrtick_restart(rq); | |
260 | rq->hrtick_csd_pending = 0; | |
261 | rq_unlock(rq, &rf); | |
262 | } | |
263 | ||
264 | /* | |
265 | * Called to set the hrtick timer state. | |
266 | * | |
267 | * called with rq->lock held and irqs disabled | |
268 | */ | |
269 | void hrtick_start(struct rq *rq, u64 delay) | |
270 | { | |
271 | struct hrtimer *timer = &rq->hrtick_timer; | |
272 | ktime_t time; | |
273 | s64 delta; | |
274 | ||
275 | /* | |
276 | * Don't schedule slices shorter than 10000ns, that just | |
277 | * doesn't make sense and can cause timer DoS. | |
278 | */ | |
279 | delta = max_t(s64, delay, 10000LL); | |
280 | time = ktime_add_ns(timer->base->get_time(), delta); | |
281 | ||
282 | hrtimer_set_expires(timer, time); | |
283 | ||
284 | if (rq == this_rq()) { | |
285 | __hrtick_restart(rq); | |
286 | } else if (!rq->hrtick_csd_pending) { | |
287 | smp_call_function_single_async(cpu_of(rq), &rq->hrtick_csd); | |
288 | rq->hrtick_csd_pending = 1; | |
289 | } | |
290 | } | |
291 | ||
292 | #else | |
293 | /* | |
294 | * Called to set the hrtick timer state. | |
295 | * | |
296 | * called with rq->lock held and irqs disabled | |
297 | */ | |
298 | void hrtick_start(struct rq *rq, u64 delay) | |
299 | { | |
300 | /* | |
301 | * Don't schedule slices shorter than 10000ns, that just | |
302 | * doesn't make sense. Rely on vruntime for fairness. | |
303 | */ | |
304 | delay = max_t(u64, delay, 10000LL); | |
305 | hrtimer_start(&rq->hrtick_timer, ns_to_ktime(delay), | |
306 | HRTIMER_MODE_REL_PINNED); | |
307 | } | |
308 | #endif /* CONFIG_SMP */ | |
309 | ||
310 | static void hrtick_rq_init(struct rq *rq) | |
311 | { | |
312 | #ifdef CONFIG_SMP | |
313 | rq->hrtick_csd_pending = 0; | |
314 | ||
315 | rq->hrtick_csd.flags = 0; | |
316 | rq->hrtick_csd.func = __hrtick_start; | |
317 | rq->hrtick_csd.info = rq; | |
318 | #endif | |
319 | ||
320 | hrtimer_init(&rq->hrtick_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL); | |
321 | rq->hrtick_timer.function = hrtick; | |
322 | } | |
323 | #else /* CONFIG_SCHED_HRTICK */ | |
324 | static inline void hrtick_clear(struct rq *rq) | |
325 | { | |
326 | } | |
327 | ||
328 | static inline void hrtick_rq_init(struct rq *rq) | |
329 | { | |
330 | } | |
331 | #endif /* CONFIG_SCHED_HRTICK */ | |
332 | ||
333 | /* | |
334 | * cmpxchg based fetch_or, macro so it works for different integer types | |
335 | */ | |
336 | #define fetch_or(ptr, mask) \ | |
337 | ({ \ | |
338 | typeof(ptr) _ptr = (ptr); \ | |
339 | typeof(mask) _mask = (mask); \ | |
340 | typeof(*_ptr) _old, _val = *_ptr; \ | |
341 | \ | |
342 | for (;;) { \ | |
343 | _old = cmpxchg(_ptr, _val, _val | _mask); \ | |
344 | if (_old == _val) \ | |
345 | break; \ | |
346 | _val = _old; \ | |
347 | } \ | |
348 | _old; \ | |
349 | }) | |
350 | ||
351 | #if defined(CONFIG_SMP) && defined(TIF_POLLING_NRFLAG) | |
352 | /* | |
353 | * Atomically set TIF_NEED_RESCHED and test for TIF_POLLING_NRFLAG, | |
354 | * this avoids any races wrt polling state changes and thereby avoids | |
355 | * spurious IPIs. | |
356 | */ | |
357 | static bool set_nr_and_not_polling(struct task_struct *p) | |
358 | { | |
359 | struct thread_info *ti = task_thread_info(p); | |
360 | return !(fetch_or(&ti->flags, _TIF_NEED_RESCHED) & _TIF_POLLING_NRFLAG); | |
361 | } | |
362 | ||
363 | /* | |
364 | * Atomically set TIF_NEED_RESCHED if TIF_POLLING_NRFLAG is set. | |
365 | * | |
366 | * If this returns true, then the idle task promises to call | |
367 | * sched_ttwu_pending() and reschedule soon. | |
368 | */ | |
369 | static bool set_nr_if_polling(struct task_struct *p) | |
370 | { | |
371 | struct thread_info *ti = task_thread_info(p); | |
372 | typeof(ti->flags) old, val = READ_ONCE(ti->flags); | |
373 | ||
374 | for (;;) { | |
375 | if (!(val & _TIF_POLLING_NRFLAG)) | |
376 | return false; | |
377 | if (val & _TIF_NEED_RESCHED) | |
378 | return true; | |
379 | old = cmpxchg(&ti->flags, val, val | _TIF_NEED_RESCHED); | |
380 | if (old == val) | |
381 | break; | |
382 | val = old; | |
383 | } | |
384 | return true; | |
385 | } | |
386 | ||
387 | #else | |
388 | static bool set_nr_and_not_polling(struct task_struct *p) | |
389 | { | |
390 | set_tsk_need_resched(p); | |
391 | return true; | |
392 | } | |
393 | ||
394 | #ifdef CONFIG_SMP | |
395 | static bool set_nr_if_polling(struct task_struct *p) | |
396 | { | |
397 | return false; | |
398 | } | |
399 | #endif | |
400 | #endif | |
401 | ||
402 | void wake_q_add(struct wake_q_head *head, struct task_struct *task) | |
403 | { | |
404 | struct wake_q_node *node = &task->wake_q; | |
405 | ||
406 | /* | |
407 | * Atomically grab the task, if ->wake_q is !nil already it means | |
408 | * its already queued (either by us or someone else) and will get the | |
409 | * wakeup due to that. | |
410 | * | |
411 | * This cmpxchg() implies a full barrier, which pairs with the write | |
412 | * barrier implied by the wakeup in wake_up_q(). | |
413 | */ | |
414 | if (cmpxchg(&node->next, NULL, WAKE_Q_TAIL)) | |
415 | return; | |
416 | ||
417 | get_task_struct(task); | |
418 | ||
419 | /* | |
420 | * The head is context local, there can be no concurrency. | |
421 | */ | |
422 | *head->lastp = node; | |
423 | head->lastp = &node->next; | |
424 | } | |
425 | ||
426 | void wake_up_q(struct wake_q_head *head) | |
427 | { | |
428 | struct wake_q_node *node = head->first; | |
429 | ||
430 | while (node != WAKE_Q_TAIL) { | |
431 | struct task_struct *task; | |
432 | ||
433 | task = container_of(node, struct task_struct, wake_q); | |
434 | BUG_ON(!task); | |
435 | /* Task can safely be re-inserted now: */ | |
436 | node = node->next; | |
437 | task->wake_q.next = NULL; | |
438 | ||
439 | /* | |
440 | * wake_up_process() implies a wmb() to pair with the queueing | |
441 | * in wake_q_add() so as not to miss wakeups. | |
442 | */ | |
443 | wake_up_process(task); | |
444 | put_task_struct(task); | |
445 | } | |
446 | } | |
447 | ||
448 | /* | |
449 | * resched_curr - mark rq's current task 'to be rescheduled now'. | |
450 | * | |
451 | * On UP this means the setting of the need_resched flag, on SMP it | |
452 | * might also involve a cross-CPU call to trigger the scheduler on | |
453 | * the target CPU. | |
454 | */ | |
455 | void resched_curr(struct rq *rq) | |
456 | { | |
457 | struct task_struct *curr = rq->curr; | |
458 | int cpu; | |
459 | ||
460 | lockdep_assert_held(&rq->lock); | |
461 | ||
462 | if (test_tsk_need_resched(curr)) | |
463 | return; | |
464 | ||
465 | cpu = cpu_of(rq); | |
466 | ||
467 | if (cpu == smp_processor_id()) { | |
468 | set_tsk_need_resched(curr); | |
469 | set_preempt_need_resched(); | |
470 | return; | |
471 | } | |
472 | ||
473 | if (set_nr_and_not_polling(curr)) | |
474 | smp_send_reschedule(cpu); | |
475 | else | |
476 | trace_sched_wake_idle_without_ipi(cpu); | |
477 | } | |
478 | ||
479 | void resched_cpu(int cpu) | |
480 | { | |
481 | struct rq *rq = cpu_rq(cpu); | |
482 | unsigned long flags; | |
483 | ||
484 | raw_spin_lock_irqsave(&rq->lock, flags); | |
485 | if (cpu_online(cpu) || cpu == smp_processor_id()) | |
486 | resched_curr(rq); | |
487 | raw_spin_unlock_irqrestore(&rq->lock, flags); | |
488 | } | |
489 | ||
490 | #ifdef CONFIG_SMP | |
491 | #ifdef CONFIG_NO_HZ_COMMON | |
492 | /* | |
493 | * In the semi idle case, use the nearest busy CPU for migrating timers | |
494 | * from an idle CPU. This is good for power-savings. | |
495 | * | |
496 | * We don't do similar optimization for completely idle system, as | |
497 | * selecting an idle CPU will add more delays to the timers than intended | |
498 | * (as that CPU's timer base may not be uptodate wrt jiffies etc). | |
499 | */ | |
500 | int get_nohz_timer_target(void) | |
501 | { | |
502 | int i, cpu = smp_processor_id(); | |
503 | struct sched_domain *sd; | |
504 | ||
505 | if (!idle_cpu(cpu) && housekeeping_cpu(cpu, HK_FLAG_TIMER)) | |
506 | return cpu; | |
507 | ||
508 | rcu_read_lock(); | |
509 | for_each_domain(cpu, sd) { | |
510 | for_each_cpu(i, sched_domain_span(sd)) { | |
511 | if (cpu == i) | |
512 | continue; | |
513 | ||
514 | if (!idle_cpu(i) && housekeeping_cpu(i, HK_FLAG_TIMER)) { | |
515 | cpu = i; | |
516 | goto unlock; | |
517 | } | |
518 | } | |
519 | } | |
520 | ||
521 | if (!housekeeping_cpu(cpu, HK_FLAG_TIMER)) | |
522 | cpu = housekeeping_any_cpu(HK_FLAG_TIMER); | |
523 | unlock: | |
524 | rcu_read_unlock(); | |
525 | return cpu; | |
526 | } | |
527 | ||
528 | /* | |
529 | * When add_timer_on() enqueues a timer into the timer wheel of an | |
530 | * idle CPU then this timer might expire before the next timer event | |
531 | * which is scheduled to wake up that CPU. In case of a completely | |
532 | * idle system the next event might even be infinite time into the | |
533 | * future. wake_up_idle_cpu() ensures that the CPU is woken up and | |
534 | * leaves the inner idle loop so the newly added timer is taken into | |
535 | * account when the CPU goes back to idle and evaluates the timer | |
536 | * wheel for the next timer event. | |
537 | */ | |
538 | static void wake_up_idle_cpu(int cpu) | |
539 | { | |
540 | struct rq *rq = cpu_rq(cpu); | |
541 | ||
542 | if (cpu == smp_processor_id()) | |
543 | return; | |
544 | ||
545 | if (set_nr_and_not_polling(rq->idle)) | |
546 | smp_send_reschedule(cpu); | |
547 | else | |
548 | trace_sched_wake_idle_without_ipi(cpu); | |
549 | } | |
550 | ||
551 | static bool wake_up_full_nohz_cpu(int cpu) | |
552 | { | |
553 | /* | |
554 | * We just need the target to call irq_exit() and re-evaluate | |
555 | * the next tick. The nohz full kick at least implies that. | |
556 | * If needed we can still optimize that later with an | |
557 | * empty IRQ. | |
558 | */ | |
559 | if (cpu_is_offline(cpu)) | |
560 | return true; /* Don't try to wake offline CPUs. */ | |
561 | if (tick_nohz_full_cpu(cpu)) { | |
562 | if (cpu != smp_processor_id() || | |
563 | tick_nohz_tick_stopped()) | |
564 | tick_nohz_full_kick_cpu(cpu); | |
565 | return true; | |
566 | } | |
567 | ||
568 | return false; | |
569 | } | |
570 | ||
571 | /* | |
572 | * Wake up the specified CPU. If the CPU is going offline, it is the | |
573 | * caller's responsibility to deal with the lost wakeup, for example, | |
574 | * by hooking into the CPU_DEAD notifier like timers and hrtimers do. | |
575 | */ | |
576 | void wake_up_nohz_cpu(int cpu) | |
577 | { | |
578 | if (!wake_up_full_nohz_cpu(cpu)) | |
579 | wake_up_idle_cpu(cpu); | |
580 | } | |
581 | ||
582 | static inline bool got_nohz_idle_kick(void) | |
583 | { | |
584 | int cpu = smp_processor_id(); | |
585 | ||
586 | if (!(atomic_read(nohz_flags(cpu)) & NOHZ_BALANCE_KICK)) | |
587 | return false; | |
588 | ||
589 | if (idle_cpu(cpu) && !need_resched()) | |
590 | return true; | |
591 | ||
592 | /* | |
593 | * We can't run Idle Load Balance on this CPU for this time so we | |
594 | * cancel it and clear NOHZ_BALANCE_KICK | |
595 | */ | |
596 | atomic_andnot(NOHZ_BALANCE_KICK, nohz_flags(cpu)); | |
597 | return false; | |
598 | } | |
599 | ||
600 | #else /* CONFIG_NO_HZ_COMMON */ | |
601 | ||
602 | static inline bool got_nohz_idle_kick(void) | |
603 | { | |
604 | return false; | |
605 | } | |
606 | ||
607 | #endif /* CONFIG_NO_HZ_COMMON */ | |
608 | ||
609 | #ifdef CONFIG_NO_HZ_FULL | |
610 | bool sched_can_stop_tick(struct rq *rq) | |
611 | { | |
612 | int fifo_nr_running; | |
613 | ||
614 | /* Deadline tasks, even if single, need the tick */ | |
615 | if (rq->dl.dl_nr_running) | |
616 | return false; | |
617 | ||
618 | /* | |
619 | * If there are more than one RR tasks, we need the tick to effect the | |
620 | * actual RR behaviour. | |
621 | */ | |
622 | if (rq->rt.rr_nr_running) { | |
623 | if (rq->rt.rr_nr_running == 1) | |
624 | return true; | |
625 | else | |
626 | return false; | |
627 | } | |
628 | ||
629 | /* | |
630 | * If there's no RR tasks, but FIFO tasks, we can skip the tick, no | |
631 | * forced preemption between FIFO tasks. | |
632 | */ | |
633 | fifo_nr_running = rq->rt.rt_nr_running - rq->rt.rr_nr_running; | |
634 | if (fifo_nr_running) | |
635 | return true; | |
636 | ||
637 | /* | |
638 | * If there are no DL,RR/FIFO tasks, there must only be CFS tasks left; | |
639 | * if there's more than one we need the tick for involuntary | |
640 | * preemption. | |
641 | */ | |
642 | if (rq->nr_running > 1) | |
643 | return false; | |
644 | ||
645 | return true; | |
646 | } | |
647 | #endif /* CONFIG_NO_HZ_FULL */ | |
648 | ||
649 | void sched_avg_update(struct rq *rq) | |
650 | { | |
651 | s64 period = sched_avg_period(); | |
652 | ||
653 | while ((s64)(rq_clock(rq) - rq->age_stamp) > period) { | |
654 | /* | |
655 | * Inline assembly required to prevent the compiler | |
656 | * optimising this loop into a divmod call. | |
657 | * See __iter_div_u64_rem() for another example of this. | |
658 | */ | |
659 | asm("" : "+rm" (rq->age_stamp)); | |
660 | rq->age_stamp += period; | |
661 | rq->rt_avg /= 2; | |
662 | } | |
663 | } | |
664 | ||
665 | #endif /* CONFIG_SMP */ | |
666 | ||
667 | #if defined(CONFIG_RT_GROUP_SCHED) || (defined(CONFIG_FAIR_GROUP_SCHED) && \ | |
668 | (defined(CONFIG_SMP) || defined(CONFIG_CFS_BANDWIDTH))) | |
669 | /* | |
670 | * Iterate task_group tree rooted at *from, calling @down when first entering a | |
671 | * node and @up when leaving it for the final time. | |
672 | * | |
673 | * Caller must hold rcu_lock or sufficient equivalent. | |
674 | */ | |
675 | int walk_tg_tree_from(struct task_group *from, | |
676 | tg_visitor down, tg_visitor up, void *data) | |
677 | { | |
678 | struct task_group *parent, *child; | |
679 | int ret; | |
680 | ||
681 | parent = from; | |
682 | ||
683 | down: | |
684 | ret = (*down)(parent, data); | |
685 | if (ret) | |
686 | goto out; | |
687 | list_for_each_entry_rcu(child, &parent->children, siblings) { | |
688 | parent = child; | |
689 | goto down; | |
690 | ||
691 | up: | |
692 | continue; | |
693 | } | |
694 | ret = (*up)(parent, data); | |
695 | if (ret || parent == from) | |
696 | goto out; | |
697 | ||
698 | child = parent; | |
699 | parent = parent->parent; | |
700 | if (parent) | |
701 | goto up; | |
702 | out: | |
703 | return ret; | |
704 | } | |
705 | ||
706 | int tg_nop(struct task_group *tg, void *data) | |
707 | { | |
708 | return 0; | |
709 | } | |
710 | #endif | |
711 | ||
712 | static void set_load_weight(struct task_struct *p, bool update_load) | |
713 | { | |
714 | int prio = p->static_prio - MAX_RT_PRIO; | |
715 | struct load_weight *load = &p->se.load; | |
716 | ||
717 | /* | |
718 | * SCHED_IDLE tasks get minimal weight: | |
719 | */ | |
720 | if (idle_policy(p->policy)) { | |
721 | load->weight = scale_load(WEIGHT_IDLEPRIO); | |
722 | load->inv_weight = WMULT_IDLEPRIO; | |
723 | return; | |
724 | } | |
725 | ||
726 | /* | |
727 | * SCHED_OTHER tasks have to update their load when changing their | |
728 | * weight | |
729 | */ | |
730 | if (update_load && p->sched_class == &fair_sched_class) { | |
731 | reweight_task(p, prio); | |
732 | } else { | |
733 | load->weight = scale_load(sched_prio_to_weight[prio]); | |
734 | load->inv_weight = sched_prio_to_wmult[prio]; | |
735 | } | |
736 | } | |
737 | ||
738 | static inline void enqueue_task(struct rq *rq, struct task_struct *p, int flags) | |
739 | { | |
740 | if (!(flags & ENQUEUE_NOCLOCK)) | |
741 | update_rq_clock(rq); | |
742 | ||
743 | if (!(flags & ENQUEUE_RESTORE)) | |
744 | sched_info_queued(rq, p); | |
745 | ||
746 | p->sched_class->enqueue_task(rq, p, flags); | |
747 | } | |
748 | ||
749 | static inline void dequeue_task(struct rq *rq, struct task_struct *p, int flags) | |
750 | { | |
751 | if (!(flags & DEQUEUE_NOCLOCK)) | |
752 | update_rq_clock(rq); | |
753 | ||
754 | if (!(flags & DEQUEUE_SAVE)) | |
755 | sched_info_dequeued(rq, p); | |
756 | ||
757 | p->sched_class->dequeue_task(rq, p, flags); | |
758 | } | |
759 | ||
760 | void activate_task(struct rq *rq, struct task_struct *p, int flags) | |
761 | { | |
762 | if (task_contributes_to_load(p)) | |
763 | rq->nr_uninterruptible--; | |
764 | ||
765 | enqueue_task(rq, p, flags); | |
766 | } | |
767 | ||
768 | void deactivate_task(struct rq *rq, struct task_struct *p, int flags) | |
769 | { | |
770 | if (task_contributes_to_load(p)) | |
771 | rq->nr_uninterruptible++; | |
772 | ||
773 | dequeue_task(rq, p, flags); | |
774 | } | |
775 | ||
776 | /* | |
777 | * __normal_prio - return the priority that is based on the static prio | |
778 | */ | |
779 | static inline int __normal_prio(struct task_struct *p) | |
780 | { | |
781 | return p->static_prio; | |
782 | } | |
783 | ||
784 | /* | |
785 | * Calculate the expected normal priority: i.e. priority | |
786 | * without taking RT-inheritance into account. Might be | |
787 | * boosted by interactivity modifiers. Changes upon fork, | |
788 | * setprio syscalls, and whenever the interactivity | |
789 | * estimator recalculates. | |
790 | */ | |
791 | static inline int normal_prio(struct task_struct *p) | |
792 | { | |
793 | int prio; | |
794 | ||
795 | if (task_has_dl_policy(p)) | |
796 | prio = MAX_DL_PRIO-1; | |
797 | else if (task_has_rt_policy(p)) | |
798 | prio = MAX_RT_PRIO-1 - p->rt_priority; | |
799 | else | |
800 | prio = __normal_prio(p); | |
801 | return prio; | |
802 | } | |
803 | ||
804 | /* | |
805 | * Calculate the current priority, i.e. the priority | |
806 | * taken into account by the scheduler. This value might | |
807 | * be boosted by RT tasks, or might be boosted by | |
808 | * interactivity modifiers. Will be RT if the task got | |
809 | * RT-boosted. If not then it returns p->normal_prio. | |
810 | */ | |
811 | static int effective_prio(struct task_struct *p) | |
812 | { | |
813 | p->normal_prio = normal_prio(p); | |
814 | /* | |
815 | * If we are RT tasks or we were boosted to RT priority, | |
816 | * keep the priority unchanged. Otherwise, update priority | |
817 | * to the normal priority: | |
818 | */ | |
819 | if (!rt_prio(p->prio)) | |
820 | return p->normal_prio; | |
821 | return p->prio; | |
822 | } | |
823 | ||
824 | /** | |
825 | * task_curr - is this task currently executing on a CPU? | |
826 | * @p: the task in question. | |
827 | * | |
828 | * Return: 1 if the task is currently executing. 0 otherwise. | |
829 | */ | |
830 | inline int task_curr(const struct task_struct *p) | |
831 | { | |
832 | return cpu_curr(task_cpu(p)) == p; | |
833 | } | |
834 | ||
835 | /* | |
836 | * switched_from, switched_to and prio_changed must _NOT_ drop rq->lock, | |
837 | * use the balance_callback list if you want balancing. | |
838 | * | |
839 | * this means any call to check_class_changed() must be followed by a call to | |
840 | * balance_callback(). | |
841 | */ | |
842 | static inline void check_class_changed(struct rq *rq, struct task_struct *p, | |
843 | const struct sched_class *prev_class, | |
844 | int oldprio) | |
845 | { | |
846 | if (prev_class != p->sched_class) { | |
847 | if (prev_class->switched_from) | |
848 | prev_class->switched_from(rq, p); | |
849 | ||
850 | p->sched_class->switched_to(rq, p); | |
851 | } else if (oldprio != p->prio || dl_task(p)) | |
852 | p->sched_class->prio_changed(rq, p, oldprio); | |
853 | } | |
854 | ||
855 | void check_preempt_curr(struct rq *rq, struct task_struct *p, int flags) | |
856 | { | |
857 | const struct sched_class *class; | |
858 | ||
859 | if (p->sched_class == rq->curr->sched_class) { | |
860 | rq->curr->sched_class->check_preempt_curr(rq, p, flags); | |
861 | } else { | |
862 | for_each_class(class) { | |
863 | if (class == rq->curr->sched_class) | |
864 | break; | |
865 | if (class == p->sched_class) { | |
866 | resched_curr(rq); | |
867 | break; | |
868 | } | |
869 | } | |
870 | } | |
871 | ||
872 | /* | |
873 | * A queue event has occurred, and we're going to schedule. In | |
874 | * this case, we can save a useless back to back clock update. | |
875 | */ | |
876 | if (task_on_rq_queued(rq->curr) && test_tsk_need_resched(rq->curr)) | |
877 | rq_clock_skip_update(rq, true); | |
878 | } | |
879 | ||
880 | #ifdef CONFIG_SMP | |
881 | /* | |
882 | * This is how migration works: | |
883 | * | |
884 | * 1) we invoke migration_cpu_stop() on the target CPU using | |
885 | * stop_one_cpu(). | |
886 | * 2) stopper starts to run (implicitly forcing the migrated thread | |
887 | * off the CPU) | |
888 | * 3) it checks whether the migrated task is still in the wrong runqueue. | |
889 | * 4) if it's in the wrong runqueue then the migration thread removes | |
890 | * it and puts it into the right queue. | |
891 | * 5) stopper completes and stop_one_cpu() returns and the migration | |
892 | * is done. | |
893 | */ | |
894 | ||
895 | /* | |
896 | * move_queued_task - move a queued task to new rq. | |
897 | * | |
898 | * Returns (locked) new rq. Old rq's lock is released. | |
899 | */ | |
900 | static struct rq *move_queued_task(struct rq *rq, struct rq_flags *rf, | |
901 | struct task_struct *p, int new_cpu) | |
902 | { | |
903 | lockdep_assert_held(&rq->lock); | |
904 | ||
905 | p->on_rq = TASK_ON_RQ_MIGRATING; | |
906 | dequeue_task(rq, p, DEQUEUE_NOCLOCK); | |
907 | set_task_cpu(p, new_cpu); | |
908 | rq_unlock(rq, rf); | |
909 | ||
910 | rq = cpu_rq(new_cpu); | |
911 | ||
912 | rq_lock(rq, rf); | |
913 | BUG_ON(task_cpu(p) != new_cpu); | |
914 | enqueue_task(rq, p, 0); | |
915 | p->on_rq = TASK_ON_RQ_QUEUED; | |
916 | check_preempt_curr(rq, p, 0); | |
917 | ||
918 | return rq; | |
919 | } | |
920 | ||
921 | struct migration_arg { | |
922 | struct task_struct *task; | |
923 | int dest_cpu; | |
924 | }; | |
925 | ||
926 | /* | |
927 | * Move (not current) task off this CPU, onto the destination CPU. We're doing | |
928 | * this because either it can't run here any more (set_cpus_allowed() | |
929 | * away from this CPU, or CPU going down), or because we're | |
930 | * attempting to rebalance this task on exec (sched_exec). | |
931 | * | |
932 | * So we race with normal scheduler movements, but that's OK, as long | |
933 | * as the task is no longer on this CPU. | |
934 | */ | |
935 | static struct rq *__migrate_task(struct rq *rq, struct rq_flags *rf, | |
936 | struct task_struct *p, int dest_cpu) | |
937 | { | |
938 | if (p->flags & PF_KTHREAD) { | |
939 | if (unlikely(!cpu_online(dest_cpu))) | |
940 | return rq; | |
941 | } else { | |
942 | if (unlikely(!cpu_active(dest_cpu))) | |
943 | return rq; | |
944 | } | |
945 | ||
946 | /* Affinity changed (again). */ | |
947 | if (!cpumask_test_cpu(dest_cpu, &p->cpus_allowed)) | |
948 | return rq; | |
949 | ||
950 | update_rq_clock(rq); | |
951 | rq = move_queued_task(rq, rf, p, dest_cpu); | |
952 | ||
953 | return rq; | |
954 | } | |
955 | ||
956 | /* | |
957 | * migration_cpu_stop - this will be executed by a highprio stopper thread | |
958 | * and performs thread migration by bumping thread off CPU then | |
959 | * 'pushing' onto another runqueue. | |
960 | */ | |
961 | static int migration_cpu_stop(void *data) | |
962 | { | |
963 | struct migration_arg *arg = data; | |
964 | struct task_struct *p = arg->task; | |
965 | struct rq *rq = this_rq(); | |
966 | struct rq_flags rf; | |
967 | ||
968 | /* | |
969 | * The original target CPU might have gone down and we might | |
970 | * be on another CPU but it doesn't matter. | |
971 | */ | |
972 | local_irq_disable(); | |
973 | /* | |
974 | * We need to explicitly wake pending tasks before running | |
975 | * __migrate_task() such that we will not miss enforcing cpus_allowed | |
976 | * during wakeups, see set_cpus_allowed_ptr()'s TASK_WAKING test. | |
977 | */ | |
978 | sched_ttwu_pending(); | |
979 | ||
980 | raw_spin_lock(&p->pi_lock); | |
981 | rq_lock(rq, &rf); | |
982 | /* | |
983 | * If task_rq(p) != rq, it cannot be migrated here, because we're | |
984 | * holding rq->lock, if p->on_rq == 0 it cannot get enqueued because | |
985 | * we're holding p->pi_lock. | |
986 | */ | |
987 | if (task_rq(p) == rq) { | |
988 | if (task_on_rq_queued(p)) | |
989 | rq = __migrate_task(rq, &rf, p, arg->dest_cpu); | |
990 | else | |
991 | p->wake_cpu = arg->dest_cpu; | |
992 | } | |
993 | rq_unlock(rq, &rf); | |
994 | raw_spin_unlock(&p->pi_lock); | |
995 | ||
996 | local_irq_enable(); | |
997 | return 0; | |
998 | } | |
999 | ||
1000 | /* | |
1001 | * sched_class::set_cpus_allowed must do the below, but is not required to | |
1002 | * actually call this function. | |
1003 | */ | |
1004 | void set_cpus_allowed_common(struct task_struct *p, const struct cpumask *new_mask) | |
1005 | { | |
1006 | cpumask_copy(&p->cpus_allowed, new_mask); | |
1007 | p->nr_cpus_allowed = cpumask_weight(new_mask); | |
1008 | } | |
1009 | ||
1010 | void do_set_cpus_allowed(struct task_struct *p, const struct cpumask *new_mask) | |
1011 | { | |
1012 | struct rq *rq = task_rq(p); | |
1013 | bool queued, running; | |
1014 | ||
1015 | lockdep_assert_held(&p->pi_lock); | |
1016 | ||
1017 | queued = task_on_rq_queued(p); | |
1018 | running = task_current(rq, p); | |
1019 | ||
1020 | if (queued) { | |
1021 | /* | |
1022 | * Because __kthread_bind() calls this on blocked tasks without | |
1023 | * holding rq->lock. | |
1024 | */ | |
1025 | lockdep_assert_held(&rq->lock); | |
1026 | dequeue_task(rq, p, DEQUEUE_SAVE | DEQUEUE_NOCLOCK); | |
1027 | } | |
1028 | if (running) | |
1029 | put_prev_task(rq, p); | |
1030 | ||
1031 | p->sched_class->set_cpus_allowed(p, new_mask); | |
1032 | ||
1033 | if (queued) | |
1034 | enqueue_task(rq, p, ENQUEUE_RESTORE | ENQUEUE_NOCLOCK); | |
1035 | if (running) | |
1036 | set_curr_task(rq, p); | |
1037 | } | |
1038 | ||
1039 | /* | |
1040 | * Change a given task's CPU affinity. Migrate the thread to a | |
1041 | * proper CPU and schedule it away if the CPU it's executing on | |
1042 | * is removed from the allowed bitmask. | |
1043 | * | |
1044 | * NOTE: the caller must have a valid reference to the task, the | |
1045 | * task must not exit() & deallocate itself prematurely. The | |
1046 | * call is not atomic; no spinlocks may be held. | |
1047 | */ | |
1048 | static int __set_cpus_allowed_ptr(struct task_struct *p, | |
1049 | const struct cpumask *new_mask, bool check) | |
1050 | { | |
1051 | const struct cpumask *cpu_valid_mask = cpu_active_mask; | |
1052 | unsigned int dest_cpu; | |
1053 | struct rq_flags rf; | |
1054 | struct rq *rq; | |
1055 | int ret = 0; | |
1056 | ||
1057 | rq = task_rq_lock(p, &rf); | |
1058 | update_rq_clock(rq); | |
1059 | ||
1060 | if (p->flags & PF_KTHREAD) { | |
1061 | /* | |
1062 | * Kernel threads are allowed on online && !active CPUs | |
1063 | */ | |
1064 | cpu_valid_mask = cpu_online_mask; | |
1065 | } | |
1066 | ||
1067 | /* | |
1068 | * Must re-check here, to close a race against __kthread_bind(), | |
1069 | * sched_setaffinity() is not guaranteed to observe the flag. | |
1070 | */ | |
1071 | if (check && (p->flags & PF_NO_SETAFFINITY)) { | |
1072 | ret = -EINVAL; | |
1073 | goto out; | |
1074 | } | |
1075 | ||
1076 | if (cpumask_equal(&p->cpus_allowed, new_mask)) | |
1077 | goto out; | |
1078 | ||
1079 | if (!cpumask_intersects(new_mask, cpu_valid_mask)) { | |
1080 | ret = -EINVAL; | |
1081 | goto out; | |
1082 | } | |
1083 | ||
1084 | do_set_cpus_allowed(p, new_mask); | |
1085 | ||
1086 | if (p->flags & PF_KTHREAD) { | |
1087 | /* | |
1088 | * For kernel threads that do indeed end up on online && | |
1089 | * !active we want to ensure they are strict per-CPU threads. | |
1090 | */ | |
1091 | WARN_ON(cpumask_intersects(new_mask, cpu_online_mask) && | |
1092 | !cpumask_intersects(new_mask, cpu_active_mask) && | |
1093 | p->nr_cpus_allowed != 1); | |
1094 | } | |
1095 | ||
1096 | /* Can the task run on the task's current CPU? If so, we're done */ | |
1097 | if (cpumask_test_cpu(task_cpu(p), new_mask)) | |
1098 | goto out; | |
1099 | ||
1100 | dest_cpu = cpumask_any_and(cpu_valid_mask, new_mask); | |
1101 | if (task_running(rq, p) || p->state == TASK_WAKING) { | |
1102 | struct migration_arg arg = { p, dest_cpu }; | |
1103 | /* Need help from migration thread: drop lock and wait. */ | |
1104 | task_rq_unlock(rq, p, &rf); | |
1105 | stop_one_cpu(cpu_of(rq), migration_cpu_stop, &arg); | |
1106 | tlb_migrate_finish(p->mm); | |
1107 | return 0; | |
1108 | } else if (task_on_rq_queued(p)) { | |
1109 | /* | |
1110 | * OK, since we're going to drop the lock immediately | |
1111 | * afterwards anyway. | |
1112 | */ | |
1113 | rq = move_queued_task(rq, &rf, p, dest_cpu); | |
1114 | } | |
1115 | out: | |
1116 | task_rq_unlock(rq, p, &rf); | |
1117 | ||
1118 | return ret; | |
1119 | } | |
1120 | ||
1121 | int set_cpus_allowed_ptr(struct task_struct *p, const struct cpumask *new_mask) | |
1122 | { | |
1123 | return __set_cpus_allowed_ptr(p, new_mask, false); | |
1124 | } | |
1125 | EXPORT_SYMBOL_GPL(set_cpus_allowed_ptr); | |
1126 | ||
1127 | void set_task_cpu(struct task_struct *p, unsigned int new_cpu) | |
1128 | { | |
1129 | #ifdef CONFIG_SCHED_DEBUG | |
1130 | /* | |
1131 | * We should never call set_task_cpu() on a blocked task, | |
1132 | * ttwu() will sort out the placement. | |
1133 | */ | |
1134 | WARN_ON_ONCE(p->state != TASK_RUNNING && p->state != TASK_WAKING && | |
1135 | !p->on_rq); | |
1136 | ||
1137 | /* | |
1138 | * Migrating fair class task must have p->on_rq = TASK_ON_RQ_MIGRATING, | |
1139 | * because schedstat_wait_{start,end} rebase migrating task's wait_start | |
1140 | * time relying on p->on_rq. | |
1141 | */ | |
1142 | WARN_ON_ONCE(p->state == TASK_RUNNING && | |
1143 | p->sched_class == &fair_sched_class && | |
1144 | (p->on_rq && !task_on_rq_migrating(p))); | |
1145 | ||
1146 | #ifdef CONFIG_LOCKDEP | |
1147 | /* | |
1148 | * The caller should hold either p->pi_lock or rq->lock, when changing | |
1149 | * a task's CPU. ->pi_lock for waking tasks, rq->lock for runnable tasks. | |
1150 | * | |
1151 | * sched_move_task() holds both and thus holding either pins the cgroup, | |
1152 | * see task_group(). | |
1153 | * | |
1154 | * Furthermore, all task_rq users should acquire both locks, see | |
1155 | * task_rq_lock(). | |
1156 | */ | |
1157 | WARN_ON_ONCE(debug_locks && !(lockdep_is_held(&p->pi_lock) || | |
1158 | lockdep_is_held(&task_rq(p)->lock))); | |
1159 | #endif | |
1160 | /* | |
1161 | * Clearly, migrating tasks to offline CPUs is a fairly daft thing. | |
1162 | */ | |
1163 | WARN_ON_ONCE(!cpu_online(new_cpu)); | |
1164 | #endif | |
1165 | ||
1166 | trace_sched_migrate_task(p, new_cpu); | |
1167 | ||
1168 | if (task_cpu(p) != new_cpu) { | |
1169 | if (p->sched_class->migrate_task_rq) | |
1170 | p->sched_class->migrate_task_rq(p); | |
1171 | p->se.nr_migrations++; | |
1172 | perf_event_task_migrate(p); | |
1173 | } | |
1174 | ||
1175 | __set_task_cpu(p, new_cpu); | |
1176 | } | |
1177 | ||
1178 | static void __migrate_swap_task(struct task_struct *p, int cpu) | |
1179 | { | |
1180 | if (task_on_rq_queued(p)) { | |
1181 | struct rq *src_rq, *dst_rq; | |
1182 | struct rq_flags srf, drf; | |
1183 | ||
1184 | src_rq = task_rq(p); | |
1185 | dst_rq = cpu_rq(cpu); | |
1186 | ||
1187 | rq_pin_lock(src_rq, &srf); | |
1188 | rq_pin_lock(dst_rq, &drf); | |
1189 | ||
1190 | p->on_rq = TASK_ON_RQ_MIGRATING; | |
1191 | deactivate_task(src_rq, p, 0); | |
1192 | set_task_cpu(p, cpu); | |
1193 | activate_task(dst_rq, p, 0); | |
1194 | p->on_rq = TASK_ON_RQ_QUEUED; | |
1195 | check_preempt_curr(dst_rq, p, 0); | |
1196 | ||
1197 | rq_unpin_lock(dst_rq, &drf); | |
1198 | rq_unpin_lock(src_rq, &srf); | |
1199 | ||
1200 | } else { | |
1201 | /* | |
1202 | * Task isn't running anymore; make it appear like we migrated | |
1203 | * it before it went to sleep. This means on wakeup we make the | |
1204 | * previous CPU our target instead of where it really is. | |
1205 | */ | |
1206 | p->wake_cpu = cpu; | |
1207 | } | |
1208 | } | |
1209 | ||
1210 | struct migration_swap_arg { | |
1211 | struct task_struct *src_task, *dst_task; | |
1212 | int src_cpu, dst_cpu; | |
1213 | }; | |
1214 | ||
1215 | static int migrate_swap_stop(void *data) | |
1216 | { | |
1217 | struct migration_swap_arg *arg = data; | |
1218 | struct rq *src_rq, *dst_rq; | |
1219 | int ret = -EAGAIN; | |
1220 | ||
1221 | if (!cpu_active(arg->src_cpu) || !cpu_active(arg->dst_cpu)) | |
1222 | return -EAGAIN; | |
1223 | ||
1224 | src_rq = cpu_rq(arg->src_cpu); | |
1225 | dst_rq = cpu_rq(arg->dst_cpu); | |
1226 | ||
1227 | double_raw_lock(&arg->src_task->pi_lock, | |
1228 | &arg->dst_task->pi_lock); | |
1229 | double_rq_lock(src_rq, dst_rq); | |
1230 | ||
1231 | if (task_cpu(arg->dst_task) != arg->dst_cpu) | |
1232 | goto unlock; | |
1233 | ||
1234 | if (task_cpu(arg->src_task) != arg->src_cpu) | |
1235 | goto unlock; | |
1236 | ||
1237 | if (!cpumask_test_cpu(arg->dst_cpu, &arg->src_task->cpus_allowed)) | |
1238 | goto unlock; | |
1239 | ||
1240 | if (!cpumask_test_cpu(arg->src_cpu, &arg->dst_task->cpus_allowed)) | |
1241 | goto unlock; | |
1242 | ||
1243 | __migrate_swap_task(arg->src_task, arg->dst_cpu); | |
1244 | __migrate_swap_task(arg->dst_task, arg->src_cpu); | |
1245 | ||
1246 | ret = 0; | |
1247 | ||
1248 | unlock: | |
1249 | double_rq_unlock(src_rq, dst_rq); | |
1250 | raw_spin_unlock(&arg->dst_task->pi_lock); | |
1251 | raw_spin_unlock(&arg->src_task->pi_lock); | |
1252 | ||
1253 | return ret; | |
1254 | } | |
1255 | ||
1256 | /* | |
1257 | * Cross migrate two tasks | |
1258 | */ | |
1259 | int migrate_swap(struct task_struct *cur, struct task_struct *p) | |
1260 | { | |
1261 | struct migration_swap_arg arg; | |
1262 | int ret = -EINVAL; | |
1263 | ||
1264 | arg = (struct migration_swap_arg){ | |
1265 | .src_task = cur, | |
1266 | .src_cpu = task_cpu(cur), | |
1267 | .dst_task = p, | |
1268 | .dst_cpu = task_cpu(p), | |
1269 | }; | |
1270 | ||
1271 | if (arg.src_cpu == arg.dst_cpu) | |
1272 | goto out; | |
1273 | ||
1274 | /* | |
1275 | * These three tests are all lockless; this is OK since all of them | |
1276 | * will be re-checked with proper locks held further down the line. | |
1277 | */ | |
1278 | if (!cpu_active(arg.src_cpu) || !cpu_active(arg.dst_cpu)) | |
1279 | goto out; | |
1280 | ||
1281 | if (!cpumask_test_cpu(arg.dst_cpu, &arg.src_task->cpus_allowed)) | |
1282 | goto out; | |
1283 | ||
1284 | if (!cpumask_test_cpu(arg.src_cpu, &arg.dst_task->cpus_allowed)) | |
1285 | goto out; | |
1286 | ||
1287 | trace_sched_swap_numa(cur, arg.src_cpu, p, arg.dst_cpu); | |
1288 | ret = stop_two_cpus(arg.dst_cpu, arg.src_cpu, migrate_swap_stop, &arg); | |
1289 | ||
1290 | out: | |
1291 | return ret; | |
1292 | } | |
1293 | ||
1294 | /* | |
1295 | * wait_task_inactive - wait for a thread to unschedule. | |
1296 | * | |
1297 | * If @match_state is nonzero, it's the @p->state value just checked and | |
1298 | * not expected to change. If it changes, i.e. @p might have woken up, | |
1299 | * then return zero. When we succeed in waiting for @p to be off its CPU, | |
1300 | * we return a positive number (its total switch count). If a second call | |
1301 | * a short while later returns the same number, the caller can be sure that | |
1302 | * @p has remained unscheduled the whole time. | |
1303 | * | |
1304 | * The caller must ensure that the task *will* unschedule sometime soon, | |
1305 | * else this function might spin for a *long* time. This function can't | |
1306 | * be called with interrupts off, or it may introduce deadlock with | |
1307 | * smp_call_function() if an IPI is sent by the same process we are | |
1308 | * waiting to become inactive. | |
1309 | */ | |
1310 | unsigned long wait_task_inactive(struct task_struct *p, long match_state) | |
1311 | { | |
1312 | int running, queued; | |
1313 | struct rq_flags rf; | |
1314 | unsigned long ncsw; | |
1315 | struct rq *rq; | |
1316 | ||
1317 | for (;;) { | |
1318 | /* | |
1319 | * We do the initial early heuristics without holding | |
1320 | * any task-queue locks at all. We'll only try to get | |
1321 | * the runqueue lock when things look like they will | |
1322 | * work out! | |
1323 | */ | |
1324 | rq = task_rq(p); | |
1325 | ||
1326 | /* | |
1327 | * If the task is actively running on another CPU | |
1328 | * still, just relax and busy-wait without holding | |
1329 | * any locks. | |
1330 | * | |
1331 | * NOTE! Since we don't hold any locks, it's not | |
1332 | * even sure that "rq" stays as the right runqueue! | |
1333 | * But we don't care, since "task_running()" will | |
1334 | * return false if the runqueue has changed and p | |
1335 | * is actually now running somewhere else! | |
1336 | */ | |
1337 | while (task_running(rq, p)) { | |
1338 | if (match_state && unlikely(p->state != match_state)) | |
1339 | return 0; | |
1340 | cpu_relax(); | |
1341 | } | |
1342 | ||
1343 | /* | |
1344 | * Ok, time to look more closely! We need the rq | |
1345 | * lock now, to be *sure*. If we're wrong, we'll | |
1346 | * just go back and repeat. | |
1347 | */ | |
1348 | rq = task_rq_lock(p, &rf); | |
1349 | trace_sched_wait_task(p); | |
1350 | running = task_running(rq, p); | |
1351 | queued = task_on_rq_queued(p); | |
1352 | ncsw = 0; | |
1353 | if (!match_state || p->state == match_state) | |
1354 | ncsw = p->nvcsw | LONG_MIN; /* sets MSB */ | |
1355 | task_rq_unlock(rq, p, &rf); | |
1356 | ||
1357 | /* | |
1358 | * If it changed from the expected state, bail out now. | |
1359 | */ | |
1360 | if (unlikely(!ncsw)) | |
1361 | break; | |
1362 | ||
1363 | /* | |
1364 | * Was it really running after all now that we | |
1365 | * checked with the proper locks actually held? | |
1366 | * | |
1367 | * Oops. Go back and try again.. | |
1368 | */ | |
1369 | if (unlikely(running)) { | |
1370 | cpu_relax(); | |
1371 | continue; | |
1372 | } | |
1373 | ||
1374 | /* | |
1375 | * It's not enough that it's not actively running, | |
1376 | * it must be off the runqueue _entirely_, and not | |
1377 | * preempted! | |
1378 | * | |
1379 | * So if it was still runnable (but just not actively | |
1380 | * running right now), it's preempted, and we should | |
1381 | * yield - it could be a while. | |
1382 | */ | |
1383 | if (unlikely(queued)) { | |
1384 | ktime_t to = NSEC_PER_SEC / HZ; | |
1385 | ||
1386 | set_current_state(TASK_UNINTERRUPTIBLE); | |
1387 | schedule_hrtimeout(&to, HRTIMER_MODE_REL); | |
1388 | continue; | |
1389 | } | |
1390 | ||
1391 | /* | |
1392 | * Ahh, all good. It wasn't running, and it wasn't | |
1393 | * runnable, which means that it will never become | |
1394 | * running in the future either. We're all done! | |
1395 | */ | |
1396 | break; | |
1397 | } | |
1398 | ||
1399 | return ncsw; | |
1400 | } | |
1401 | ||
1402 | /*** | |
1403 | * kick_process - kick a running thread to enter/exit the kernel | |
1404 | * @p: the to-be-kicked thread | |
1405 | * | |
1406 | * Cause a process which is running on another CPU to enter | |
1407 | * kernel-mode, without any delay. (to get signals handled.) | |
1408 | * | |
1409 | * NOTE: this function doesn't have to take the runqueue lock, | |
1410 | * because all it wants to ensure is that the remote task enters | |
1411 | * the kernel. If the IPI races and the task has been migrated | |
1412 | * to another CPU then no harm is done and the purpose has been | |
1413 | * achieved as well. | |
1414 | */ | |
1415 | void kick_process(struct task_struct *p) | |
1416 | { | |
1417 | int cpu; | |
1418 | ||
1419 | preempt_disable(); | |
1420 | cpu = task_cpu(p); | |
1421 | if ((cpu != smp_processor_id()) && task_curr(p)) | |
1422 | smp_send_reschedule(cpu); | |
1423 | preempt_enable(); | |
1424 | } | |
1425 | EXPORT_SYMBOL_GPL(kick_process); | |
1426 | ||
1427 | /* | |
1428 | * ->cpus_allowed is protected by both rq->lock and p->pi_lock | |
1429 | * | |
1430 | * A few notes on cpu_active vs cpu_online: | |
1431 | * | |
1432 | * - cpu_active must be a subset of cpu_online | |
1433 | * | |
1434 | * - on CPU-up we allow per-CPU kthreads on the online && !active CPU, | |
1435 | * see __set_cpus_allowed_ptr(). At this point the newly online | |
1436 | * CPU isn't yet part of the sched domains, and balancing will not | |
1437 | * see it. | |
1438 | * | |
1439 | * - on CPU-down we clear cpu_active() to mask the sched domains and | |
1440 | * avoid the load balancer to place new tasks on the to be removed | |
1441 | * CPU. Existing tasks will remain running there and will be taken | |
1442 | * off. | |
1443 | * | |
1444 | * This means that fallback selection must not select !active CPUs. | |
1445 | * And can assume that any active CPU must be online. Conversely | |
1446 | * select_task_rq() below may allow selection of !active CPUs in order | |
1447 | * to satisfy the above rules. | |
1448 | */ | |
1449 | static int select_fallback_rq(int cpu, struct task_struct *p) | |
1450 | { | |
1451 | int nid = cpu_to_node(cpu); | |
1452 | const struct cpumask *nodemask = NULL; | |
1453 | enum { cpuset, possible, fail } state = cpuset; | |
1454 | int dest_cpu; | |
1455 | ||
1456 | /* | |
1457 | * If the node that the CPU is on has been offlined, cpu_to_node() | |
1458 | * will return -1. There is no CPU on the node, and we should | |
1459 | * select the CPU on the other node. | |
1460 | */ | |
1461 | if (nid != -1) { | |
1462 | nodemask = cpumask_of_node(nid); | |
1463 | ||
1464 | /* Look for allowed, online CPU in same node. */ | |
1465 | for_each_cpu(dest_cpu, nodemask) { | |
1466 | if (!cpu_active(dest_cpu)) | |
1467 | continue; | |
1468 | if (cpumask_test_cpu(dest_cpu, &p->cpus_allowed)) | |
1469 | return dest_cpu; | |
1470 | } | |
1471 | } | |
1472 | ||
1473 | for (;;) { | |
1474 | /* Any allowed, online CPU? */ | |
1475 | for_each_cpu(dest_cpu, &p->cpus_allowed) { | |
1476 | if (!(p->flags & PF_KTHREAD) && !cpu_active(dest_cpu)) | |
1477 | continue; | |
1478 | if (!cpu_online(dest_cpu)) | |
1479 | continue; | |
1480 | goto out; | |
1481 | } | |
1482 | ||
1483 | /* No more Mr. Nice Guy. */ | |
1484 | switch (state) { | |
1485 | case cpuset: | |
1486 | if (IS_ENABLED(CONFIG_CPUSETS)) { | |
1487 | cpuset_cpus_allowed_fallback(p); | |
1488 | state = possible; | |
1489 | break; | |
1490 | } | |
1491 | /* Fall-through */ | |
1492 | case possible: | |
1493 | do_set_cpus_allowed(p, cpu_possible_mask); | |
1494 | state = fail; | |
1495 | break; | |
1496 | ||
1497 | case fail: | |
1498 | BUG(); | |
1499 | break; | |
1500 | } | |
1501 | } | |
1502 | ||
1503 | out: | |
1504 | if (state != cpuset) { | |
1505 | /* | |
1506 | * Don't tell them about moving exiting tasks or | |
1507 | * kernel threads (both mm NULL), since they never | |
1508 | * leave kernel. | |
1509 | */ | |
1510 | if (p->mm && printk_ratelimit()) { | |
1511 | printk_deferred("process %d (%s) no longer affine to cpu%d\n", | |
1512 | task_pid_nr(p), p->comm, cpu); | |
1513 | } | |
1514 | } | |
1515 | ||
1516 | return dest_cpu; | |
1517 | } | |
1518 | ||
1519 | /* | |
1520 | * The caller (fork, wakeup) owns p->pi_lock, ->cpus_allowed is stable. | |
1521 | */ | |
1522 | static inline | |
1523 | int select_task_rq(struct task_struct *p, int cpu, int sd_flags, int wake_flags) | |
1524 | { | |
1525 | lockdep_assert_held(&p->pi_lock); | |
1526 | ||
1527 | if (p->nr_cpus_allowed > 1) | |
1528 | cpu = p->sched_class->select_task_rq(p, cpu, sd_flags, wake_flags); | |
1529 | else | |
1530 | cpu = cpumask_any(&p->cpus_allowed); | |
1531 | ||
1532 | /* | |
1533 | * In order not to call set_task_cpu() on a blocking task we need | |
1534 | * to rely on ttwu() to place the task on a valid ->cpus_allowed | |
1535 | * CPU. | |
1536 | * | |
1537 | * Since this is common to all placement strategies, this lives here. | |
1538 | * | |
1539 | * [ this allows ->select_task() to simply return task_cpu(p) and | |
1540 | * not worry about this generic constraint ] | |
1541 | */ | |
1542 | if (unlikely(!cpumask_test_cpu(cpu, &p->cpus_allowed) || | |
1543 | !cpu_online(cpu))) | |
1544 | cpu = select_fallback_rq(task_cpu(p), p); | |
1545 | ||
1546 | return cpu; | |
1547 | } | |
1548 | ||
1549 | static void update_avg(u64 *avg, u64 sample) | |
1550 | { | |
1551 | s64 diff = sample - *avg; | |
1552 | *avg += diff >> 3; | |
1553 | } | |
1554 | ||
1555 | void sched_set_stop_task(int cpu, struct task_struct *stop) | |
1556 | { | |
1557 | struct sched_param param = { .sched_priority = MAX_RT_PRIO - 1 }; | |
1558 | struct task_struct *old_stop = cpu_rq(cpu)->stop; | |
1559 | ||
1560 | if (stop) { | |
1561 | /* | |
1562 | * Make it appear like a SCHED_FIFO task, its something | |
1563 | * userspace knows about and won't get confused about. | |
1564 | * | |
1565 | * Also, it will make PI more or less work without too | |
1566 | * much confusion -- but then, stop work should not | |
1567 | * rely on PI working anyway. | |
1568 | */ | |
1569 | sched_setscheduler_nocheck(stop, SCHED_FIFO, ¶m); | |
1570 | ||
1571 | stop->sched_class = &stop_sched_class; | |
1572 | } | |
1573 | ||
1574 | cpu_rq(cpu)->stop = stop; | |
1575 | ||
1576 | if (old_stop) { | |
1577 | /* | |
1578 | * Reset it back to a normal scheduling class so that | |
1579 | * it can die in pieces. | |
1580 | */ | |
1581 | old_stop->sched_class = &rt_sched_class; | |
1582 | } | |
1583 | } | |
1584 | ||
1585 | #else | |
1586 | ||
1587 | static inline int __set_cpus_allowed_ptr(struct task_struct *p, | |
1588 | const struct cpumask *new_mask, bool check) | |
1589 | { | |
1590 | return set_cpus_allowed_ptr(p, new_mask); | |
1591 | } | |
1592 | ||
1593 | #endif /* CONFIG_SMP */ | |
1594 | ||
1595 | static void | |
1596 | ttwu_stat(struct task_struct *p, int cpu, int wake_flags) | |
1597 | { | |
1598 | struct rq *rq; | |
1599 | ||
1600 | if (!schedstat_enabled()) | |
1601 | return; | |
1602 | ||
1603 | rq = this_rq(); | |
1604 | ||
1605 | #ifdef CONFIG_SMP | |
1606 | if (cpu == rq->cpu) { | |
1607 | __schedstat_inc(rq->ttwu_local); | |
1608 | __schedstat_inc(p->se.statistics.nr_wakeups_local); | |
1609 | } else { | |
1610 | struct sched_domain *sd; | |
1611 | ||
1612 | __schedstat_inc(p->se.statistics.nr_wakeups_remote); | |
1613 | rcu_read_lock(); | |
1614 | for_each_domain(rq->cpu, sd) { | |
1615 | if (cpumask_test_cpu(cpu, sched_domain_span(sd))) { | |
1616 | __schedstat_inc(sd->ttwu_wake_remote); | |
1617 | break; | |
1618 | } | |
1619 | } | |
1620 | rcu_read_unlock(); | |
1621 | } | |
1622 | ||
1623 | if (wake_flags & WF_MIGRATED) | |
1624 | __schedstat_inc(p->se.statistics.nr_wakeups_migrate); | |
1625 | #endif /* CONFIG_SMP */ | |
1626 | ||
1627 | __schedstat_inc(rq->ttwu_count); | |
1628 | __schedstat_inc(p->se.statistics.nr_wakeups); | |
1629 | ||
1630 | if (wake_flags & WF_SYNC) | |
1631 | __schedstat_inc(p->se.statistics.nr_wakeups_sync); | |
1632 | } | |
1633 | ||
1634 | static inline void ttwu_activate(struct rq *rq, struct task_struct *p, int en_flags) | |
1635 | { | |
1636 | activate_task(rq, p, en_flags); | |
1637 | p->on_rq = TASK_ON_RQ_QUEUED; | |
1638 | ||
1639 | /* If a worker is waking up, notify the workqueue: */ | |
1640 | if (p->flags & PF_WQ_WORKER) | |
1641 | wq_worker_waking_up(p, cpu_of(rq)); | |
1642 | } | |
1643 | ||
1644 | /* | |
1645 | * Mark the task runnable and perform wakeup-preemption. | |
1646 | */ | |
1647 | static void ttwu_do_wakeup(struct rq *rq, struct task_struct *p, int wake_flags, | |
1648 | struct rq_flags *rf) | |
1649 | { | |
1650 | check_preempt_curr(rq, p, wake_flags); | |
1651 | p->state = TASK_RUNNING; | |
1652 | trace_sched_wakeup(p); | |
1653 | ||
1654 | #ifdef CONFIG_SMP | |
1655 | if (p->sched_class->task_woken) { | |
1656 | /* | |
1657 | * Our task @p is fully woken up and running; so its safe to | |
1658 | * drop the rq->lock, hereafter rq is only used for statistics. | |
1659 | */ | |
1660 | rq_unpin_lock(rq, rf); | |
1661 | p->sched_class->task_woken(rq, p); | |
1662 | rq_repin_lock(rq, rf); | |
1663 | } | |
1664 | ||
1665 | if (rq->idle_stamp) { | |
1666 | u64 delta = rq_clock(rq) - rq->idle_stamp; | |
1667 | u64 max = 2*rq->max_idle_balance_cost; | |
1668 | ||
1669 | update_avg(&rq->avg_idle, delta); | |
1670 | ||
1671 | if (rq->avg_idle > max) | |
1672 | rq->avg_idle = max; | |
1673 | ||
1674 | rq->idle_stamp = 0; | |
1675 | } | |
1676 | #endif | |
1677 | } | |
1678 | ||
1679 | static void | |
1680 | ttwu_do_activate(struct rq *rq, struct task_struct *p, int wake_flags, | |
1681 | struct rq_flags *rf) | |
1682 | { | |
1683 | int en_flags = ENQUEUE_WAKEUP | ENQUEUE_NOCLOCK; | |
1684 | ||
1685 | lockdep_assert_held(&rq->lock); | |
1686 | ||
1687 | #ifdef CONFIG_SMP | |
1688 | if (p->sched_contributes_to_load) | |
1689 | rq->nr_uninterruptible--; | |
1690 | ||
1691 | if (wake_flags & WF_MIGRATED) | |
1692 | en_flags |= ENQUEUE_MIGRATED; | |
1693 | #endif | |
1694 | ||
1695 | ttwu_activate(rq, p, en_flags); | |
1696 | ttwu_do_wakeup(rq, p, wake_flags, rf); | |
1697 | } | |
1698 | ||
1699 | /* | |
1700 | * Called in case the task @p isn't fully descheduled from its runqueue, | |
1701 | * in this case we must do a remote wakeup. Its a 'light' wakeup though, | |
1702 | * since all we need to do is flip p->state to TASK_RUNNING, since | |
1703 | * the task is still ->on_rq. | |
1704 | */ | |
1705 | static int ttwu_remote(struct task_struct *p, int wake_flags) | |
1706 | { | |
1707 | struct rq_flags rf; | |
1708 | struct rq *rq; | |
1709 | int ret = 0; | |
1710 | ||
1711 | rq = __task_rq_lock(p, &rf); | |
1712 | if (task_on_rq_queued(p)) { | |
1713 | /* check_preempt_curr() may use rq clock */ | |
1714 | update_rq_clock(rq); | |
1715 | ttwu_do_wakeup(rq, p, wake_flags, &rf); | |
1716 | ret = 1; | |
1717 | } | |
1718 | __task_rq_unlock(rq, &rf); | |
1719 | ||
1720 | return ret; | |
1721 | } | |
1722 | ||
1723 | #ifdef CONFIG_SMP | |
1724 | void sched_ttwu_pending(void) | |
1725 | { | |
1726 | struct rq *rq = this_rq(); | |
1727 | struct llist_node *llist = llist_del_all(&rq->wake_list); | |
1728 | struct task_struct *p, *t; | |
1729 | struct rq_flags rf; | |
1730 | ||
1731 | if (!llist) | |
1732 | return; | |
1733 | ||
1734 | rq_lock_irqsave(rq, &rf); | |
1735 | update_rq_clock(rq); | |
1736 | ||
1737 | llist_for_each_entry_safe(p, t, llist, wake_entry) | |
1738 | ttwu_do_activate(rq, p, p->sched_remote_wakeup ? WF_MIGRATED : 0, &rf); | |
1739 | ||
1740 | rq_unlock_irqrestore(rq, &rf); | |
1741 | } | |
1742 | ||
1743 | void scheduler_ipi(void) | |
1744 | { | |
1745 | /* | |
1746 | * Fold TIF_NEED_RESCHED into the preempt_count; anybody setting | |
1747 | * TIF_NEED_RESCHED remotely (for the first time) will also send | |
1748 | * this IPI. | |
1749 | */ | |
1750 | preempt_fold_need_resched(); | |
1751 | ||
1752 | if (llist_empty(&this_rq()->wake_list) && !got_nohz_idle_kick()) | |
1753 | return; | |
1754 | ||
1755 | /* | |
1756 | * Not all reschedule IPI handlers call irq_enter/irq_exit, since | |
1757 | * traditionally all their work was done from the interrupt return | |
1758 | * path. Now that we actually do some work, we need to make sure | |
1759 | * we do call them. | |
1760 | * | |
1761 | * Some archs already do call them, luckily irq_enter/exit nest | |
1762 | * properly. | |
1763 | * | |
1764 | * Arguably we should visit all archs and update all handlers, | |
1765 | * however a fair share of IPIs are still resched only so this would | |
1766 | * somewhat pessimize the simple resched case. | |
1767 | */ | |
1768 | irq_enter(); | |
1769 | sched_ttwu_pending(); | |
1770 | ||
1771 | /* | |
1772 | * Check if someone kicked us for doing the nohz idle load balance. | |
1773 | */ | |
1774 | if (unlikely(got_nohz_idle_kick())) { | |
1775 | this_rq()->idle_balance = 1; | |
1776 | raise_softirq_irqoff(SCHED_SOFTIRQ); | |
1777 | } | |
1778 | irq_exit(); | |
1779 | } | |
1780 | ||
1781 | static void ttwu_queue_remote(struct task_struct *p, int cpu, int wake_flags) | |
1782 | { | |
1783 | struct rq *rq = cpu_rq(cpu); | |
1784 | ||
1785 | p->sched_remote_wakeup = !!(wake_flags & WF_MIGRATED); | |
1786 | ||
1787 | if (llist_add(&p->wake_entry, &cpu_rq(cpu)->wake_list)) { | |
1788 | if (!set_nr_if_polling(rq->idle)) | |
1789 | smp_send_reschedule(cpu); | |
1790 | else | |
1791 | trace_sched_wake_idle_without_ipi(cpu); | |
1792 | } | |
1793 | } | |
1794 | ||
1795 | void wake_up_if_idle(int cpu) | |
1796 | { | |
1797 | struct rq *rq = cpu_rq(cpu); | |
1798 | struct rq_flags rf; | |
1799 | ||
1800 | rcu_read_lock(); | |
1801 | ||
1802 | if (!is_idle_task(rcu_dereference(rq->curr))) | |
1803 | goto out; | |
1804 | ||
1805 | if (set_nr_if_polling(rq->idle)) { | |
1806 | trace_sched_wake_idle_without_ipi(cpu); | |
1807 | } else { | |
1808 | rq_lock_irqsave(rq, &rf); | |
1809 | if (is_idle_task(rq->curr)) | |
1810 | smp_send_reschedule(cpu); | |
1811 | /* Else CPU is not idle, do nothing here: */ | |
1812 | rq_unlock_irqrestore(rq, &rf); | |
1813 | } | |
1814 | ||
1815 | out: | |
1816 | rcu_read_unlock(); | |
1817 | } | |
1818 | ||
1819 | bool cpus_share_cache(int this_cpu, int that_cpu) | |
1820 | { | |
1821 | return per_cpu(sd_llc_id, this_cpu) == per_cpu(sd_llc_id, that_cpu); | |
1822 | } | |
1823 | #endif /* CONFIG_SMP */ | |
1824 | ||
1825 | static void ttwu_queue(struct task_struct *p, int cpu, int wake_flags) | |
1826 | { | |
1827 | struct rq *rq = cpu_rq(cpu); | |
1828 | struct rq_flags rf; | |
1829 | ||
1830 | #if defined(CONFIG_SMP) | |
1831 | if (sched_feat(TTWU_QUEUE) && !cpus_share_cache(smp_processor_id(), cpu)) { | |
1832 | sched_clock_cpu(cpu); /* Sync clocks across CPUs */ | |
1833 | ttwu_queue_remote(p, cpu, wake_flags); | |
1834 | return; | |
1835 | } | |
1836 | #endif | |
1837 | ||
1838 | rq_lock(rq, &rf); | |
1839 | update_rq_clock(rq); | |
1840 | ttwu_do_activate(rq, p, wake_flags, &rf); | |
1841 | rq_unlock(rq, &rf); | |
1842 | } | |
1843 | ||
1844 | /* | |
1845 | * Notes on Program-Order guarantees on SMP systems. | |
1846 | * | |
1847 | * MIGRATION | |
1848 | * | |
1849 | * The basic program-order guarantee on SMP systems is that when a task [t] | |
1850 | * migrates, all its activity on its old CPU [c0] happens-before any subsequent | |
1851 | * execution on its new CPU [c1]. | |
1852 | * | |
1853 | * For migration (of runnable tasks) this is provided by the following means: | |
1854 | * | |
1855 | * A) UNLOCK of the rq(c0)->lock scheduling out task t | |
1856 | * B) migration for t is required to synchronize *both* rq(c0)->lock and | |
1857 | * rq(c1)->lock (if not at the same time, then in that order). | |
1858 | * C) LOCK of the rq(c1)->lock scheduling in task | |
1859 | * | |
1860 | * Transitivity guarantees that B happens after A and C after B. | |
1861 | * Note: we only require RCpc transitivity. | |
1862 | * Note: the CPU doing B need not be c0 or c1 | |
1863 | * | |
1864 | * Example: | |
1865 | * | |
1866 | * CPU0 CPU1 CPU2 | |
1867 | * | |
1868 | * LOCK rq(0)->lock | |
1869 | * sched-out X | |
1870 | * sched-in Y | |
1871 | * UNLOCK rq(0)->lock | |
1872 | * | |
1873 | * LOCK rq(0)->lock // orders against CPU0 | |
1874 | * dequeue X | |
1875 | * UNLOCK rq(0)->lock | |
1876 | * | |
1877 | * LOCK rq(1)->lock | |
1878 | * enqueue X | |
1879 | * UNLOCK rq(1)->lock | |
1880 | * | |
1881 | * LOCK rq(1)->lock // orders against CPU2 | |
1882 | * sched-out Z | |
1883 | * sched-in X | |
1884 | * UNLOCK rq(1)->lock | |
1885 | * | |
1886 | * | |
1887 | * BLOCKING -- aka. SLEEP + WAKEUP | |
1888 | * | |
1889 | * For blocking we (obviously) need to provide the same guarantee as for | |
1890 | * migration. However the means are completely different as there is no lock | |
1891 | * chain to provide order. Instead we do: | |
1892 | * | |
1893 | * 1) smp_store_release(X->on_cpu, 0) | |
1894 | * 2) smp_cond_load_acquire(!X->on_cpu) | |
1895 | * | |
1896 | * Example: | |
1897 | * | |
1898 | * CPU0 (schedule) CPU1 (try_to_wake_up) CPU2 (schedule) | |
1899 | * | |
1900 | * LOCK rq(0)->lock LOCK X->pi_lock | |
1901 | * dequeue X | |
1902 | * sched-out X | |
1903 | * smp_store_release(X->on_cpu, 0); | |
1904 | * | |
1905 | * smp_cond_load_acquire(&X->on_cpu, !VAL); | |
1906 | * X->state = WAKING | |
1907 | * set_task_cpu(X,2) | |
1908 | * | |
1909 | * LOCK rq(2)->lock | |
1910 | * enqueue X | |
1911 | * X->state = RUNNING | |
1912 | * UNLOCK rq(2)->lock | |
1913 | * | |
1914 | * LOCK rq(2)->lock // orders against CPU1 | |
1915 | * sched-out Z | |
1916 | * sched-in X | |
1917 | * UNLOCK rq(2)->lock | |
1918 | * | |
1919 | * UNLOCK X->pi_lock | |
1920 | * UNLOCK rq(0)->lock | |
1921 | * | |
1922 | * | |
1923 | * However; for wakeups there is a second guarantee we must provide, namely we | |
1924 | * must observe the state that lead to our wakeup. That is, not only must our | |
1925 | * task observe its own prior state, it must also observe the stores prior to | |
1926 | * its wakeup. | |
1927 | * | |
1928 | * This means that any means of doing remote wakeups must order the CPU doing | |
1929 | * the wakeup against the CPU the task is going to end up running on. This, | |
1930 | * however, is already required for the regular Program-Order guarantee above, | |
1931 | * since the waking CPU is the one issueing the ACQUIRE (smp_cond_load_acquire). | |
1932 | * | |
1933 | */ | |
1934 | ||
1935 | /** | |
1936 | * try_to_wake_up - wake up a thread | |
1937 | * @p: the thread to be awakened | |
1938 | * @state: the mask of task states that can be woken | |
1939 | * @wake_flags: wake modifier flags (WF_*) | |
1940 | * | |
1941 | * If (@state & @p->state) @p->state = TASK_RUNNING. | |
1942 | * | |
1943 | * If the task was not queued/runnable, also place it back on a runqueue. | |
1944 | * | |
1945 | * Atomic against schedule() which would dequeue a task, also see | |
1946 | * set_current_state(). | |
1947 | * | |
1948 | * Return: %true if @p->state changes (an actual wakeup was done), | |
1949 | * %false otherwise. | |
1950 | */ | |
1951 | static int | |
1952 | try_to_wake_up(struct task_struct *p, unsigned int state, int wake_flags) | |
1953 | { | |
1954 | unsigned long flags; | |
1955 | int cpu, success = 0; | |
1956 | ||
1957 | /* | |
1958 | * If we are going to wake up a thread waiting for CONDITION we | |
1959 | * need to ensure that CONDITION=1 done by the caller can not be | |
1960 | * reordered with p->state check below. This pairs with mb() in | |
1961 | * set_current_state() the waiting thread does. | |
1962 | */ | |
1963 | raw_spin_lock_irqsave(&p->pi_lock, flags); | |
1964 | smp_mb__after_spinlock(); | |
1965 | if (!(p->state & state)) | |
1966 | goto out; | |
1967 | ||
1968 | trace_sched_waking(p); | |
1969 | ||
1970 | /* We're going to change ->state: */ | |
1971 | success = 1; | |
1972 | cpu = task_cpu(p); | |
1973 | ||
1974 | /* | |
1975 | * Ensure we load p->on_rq _after_ p->state, otherwise it would | |
1976 | * be possible to, falsely, observe p->on_rq == 0 and get stuck | |
1977 | * in smp_cond_load_acquire() below. | |
1978 | * | |
1979 | * sched_ttwu_pending() try_to_wake_up() | |
1980 | * [S] p->on_rq = 1; [L] P->state | |
1981 | * UNLOCK rq->lock -----. | |
1982 | * \ | |
1983 | * +--- RMB | |
1984 | * schedule() / | |
1985 | * LOCK rq->lock -----' | |
1986 | * UNLOCK rq->lock | |
1987 | * | |
1988 | * [task p] | |
1989 | * [S] p->state = UNINTERRUPTIBLE [L] p->on_rq | |
1990 | * | |
1991 | * Pairs with the UNLOCK+LOCK on rq->lock from the | |
1992 | * last wakeup of our task and the schedule that got our task | |
1993 | * current. | |
1994 | */ | |
1995 | smp_rmb(); | |
1996 | if (p->on_rq && ttwu_remote(p, wake_flags)) | |
1997 | goto stat; | |
1998 | ||
1999 | #ifdef CONFIG_SMP | |
2000 | /* | |
2001 | * Ensure we load p->on_cpu _after_ p->on_rq, otherwise it would be | |
2002 | * possible to, falsely, observe p->on_cpu == 0. | |
2003 | * | |
2004 | * One must be running (->on_cpu == 1) in order to remove oneself | |
2005 | * from the runqueue. | |
2006 | * | |
2007 | * [S] ->on_cpu = 1; [L] ->on_rq | |
2008 | * UNLOCK rq->lock | |
2009 | * RMB | |
2010 | * LOCK rq->lock | |
2011 | * [S] ->on_rq = 0; [L] ->on_cpu | |
2012 | * | |
2013 | * Pairs with the full barrier implied in the UNLOCK+LOCK on rq->lock | |
2014 | * from the consecutive calls to schedule(); the first switching to our | |
2015 | * task, the second putting it to sleep. | |
2016 | */ | |
2017 | smp_rmb(); | |
2018 | ||
2019 | /* | |
2020 | * If the owning (remote) CPU is still in the middle of schedule() with | |
2021 | * this task as prev, wait until its done referencing the task. | |
2022 | * | |
2023 | * Pairs with the smp_store_release() in finish_task(). | |
2024 | * | |
2025 | * This ensures that tasks getting woken will be fully ordered against | |
2026 | * their previous state and preserve Program Order. | |
2027 | */ | |
2028 | smp_cond_load_acquire(&p->on_cpu, !VAL); | |
2029 | ||
2030 | p->sched_contributes_to_load = !!task_contributes_to_load(p); | |
2031 | p->state = TASK_WAKING; | |
2032 | ||
2033 | if (p->in_iowait) { | |
2034 | delayacct_blkio_end(p); | |
2035 | atomic_dec(&task_rq(p)->nr_iowait); | |
2036 | } | |
2037 | ||
2038 | cpu = select_task_rq(p, p->wake_cpu, SD_BALANCE_WAKE, wake_flags); | |
2039 | if (task_cpu(p) != cpu) { | |
2040 | wake_flags |= WF_MIGRATED; | |
2041 | set_task_cpu(p, cpu); | |
2042 | } | |
2043 | ||
2044 | #else /* CONFIG_SMP */ | |
2045 | ||
2046 | if (p->in_iowait) { | |
2047 | delayacct_blkio_end(p); | |
2048 | atomic_dec(&task_rq(p)->nr_iowait); | |
2049 | } | |
2050 | ||
2051 | #endif /* CONFIG_SMP */ | |
2052 | ||
2053 | ttwu_queue(p, cpu, wake_flags); | |
2054 | stat: | |
2055 | ttwu_stat(p, cpu, wake_flags); | |
2056 | out: | |
2057 | raw_spin_unlock_irqrestore(&p->pi_lock, flags); | |
2058 | ||
2059 | return success; | |
2060 | } | |
2061 | ||
2062 | /** | |
2063 | * try_to_wake_up_local - try to wake up a local task with rq lock held | |
2064 | * @p: the thread to be awakened | |
2065 | * @rf: request-queue flags for pinning | |
2066 | * | |
2067 | * Put @p on the run-queue if it's not already there. The caller must | |
2068 | * ensure that this_rq() is locked, @p is bound to this_rq() and not | |
2069 | * the current task. | |
2070 | */ | |
2071 | static void try_to_wake_up_local(struct task_struct *p, struct rq_flags *rf) | |
2072 | { | |
2073 | struct rq *rq = task_rq(p); | |
2074 | ||
2075 | if (WARN_ON_ONCE(rq != this_rq()) || | |
2076 | WARN_ON_ONCE(p == current)) | |
2077 | return; | |
2078 | ||
2079 | lockdep_assert_held(&rq->lock); | |
2080 | ||
2081 | if (!raw_spin_trylock(&p->pi_lock)) { | |
2082 | /* | |
2083 | * This is OK, because current is on_cpu, which avoids it being | |
2084 | * picked for load-balance and preemption/IRQs are still | |
2085 | * disabled avoiding further scheduler activity on it and we've | |
2086 | * not yet picked a replacement task. | |
2087 | */ | |
2088 | rq_unlock(rq, rf); | |
2089 | raw_spin_lock(&p->pi_lock); | |
2090 | rq_relock(rq, rf); | |
2091 | } | |
2092 | ||
2093 | if (!(p->state & TASK_NORMAL)) | |
2094 | goto out; | |
2095 | ||
2096 | trace_sched_waking(p); | |
2097 | ||
2098 | if (!task_on_rq_queued(p)) { | |
2099 | if (p->in_iowait) { | |
2100 | delayacct_blkio_end(p); | |
2101 | atomic_dec(&rq->nr_iowait); | |
2102 | } | |
2103 | ttwu_activate(rq, p, ENQUEUE_WAKEUP | ENQUEUE_NOCLOCK); | |
2104 | } | |
2105 | ||
2106 | ttwu_do_wakeup(rq, p, 0, rf); | |
2107 | ttwu_stat(p, smp_processor_id(), 0); | |
2108 | out: | |
2109 | raw_spin_unlock(&p->pi_lock); | |
2110 | } | |
2111 | ||
2112 | /** | |
2113 | * wake_up_process - Wake up a specific process | |
2114 | * @p: The process to be woken up. | |
2115 | * | |
2116 | * Attempt to wake up the nominated process and move it to the set of runnable | |
2117 | * processes. | |
2118 | * | |
2119 | * Return: 1 if the process was woken up, 0 if it was already running. | |
2120 | * | |
2121 | * It may be assumed that this function implies a write memory barrier before | |
2122 | * changing the task state if and only if any tasks are woken up. | |
2123 | */ | |
2124 | int wake_up_process(struct task_struct *p) | |
2125 | { | |
2126 | return try_to_wake_up(p, TASK_NORMAL, 0); | |
2127 | } | |
2128 | EXPORT_SYMBOL(wake_up_process); | |
2129 | ||
2130 | int wake_up_state(struct task_struct *p, unsigned int state) | |
2131 | { | |
2132 | return try_to_wake_up(p, state, 0); | |
2133 | } | |
2134 | ||
2135 | /* | |
2136 | * Perform scheduler related setup for a newly forked process p. | |
2137 | * p is forked by current. | |
2138 | * | |
2139 | * __sched_fork() is basic setup used by init_idle() too: | |
2140 | */ | |
2141 | static void __sched_fork(unsigned long clone_flags, struct task_struct *p) | |
2142 | { | |
2143 | p->on_rq = 0; | |
2144 | ||
2145 | p->se.on_rq = 0; | |
2146 | p->se.exec_start = 0; | |
2147 | p->se.sum_exec_runtime = 0; | |
2148 | p->se.prev_sum_exec_runtime = 0; | |
2149 | p->se.nr_migrations = 0; | |
2150 | p->se.vruntime = 0; | |
2151 | INIT_LIST_HEAD(&p->se.group_node); | |
2152 | ||
2153 | #ifdef CONFIG_FAIR_GROUP_SCHED | |
2154 | p->se.cfs_rq = NULL; | |
2155 | #endif | |
2156 | ||
2157 | #ifdef CONFIG_SCHEDSTATS | |
2158 | /* Even if schedstat is disabled, there should not be garbage */ | |
2159 | memset(&p->se.statistics, 0, sizeof(p->se.statistics)); | |
2160 | #endif | |
2161 | ||
2162 | RB_CLEAR_NODE(&p->dl.rb_node); | |
2163 | init_dl_task_timer(&p->dl); | |
2164 | init_dl_inactive_task_timer(&p->dl); | |
2165 | __dl_clear_params(p); | |
2166 | ||
2167 | INIT_LIST_HEAD(&p->rt.run_list); | |
2168 | p->rt.timeout = 0; | |
2169 | p->rt.time_slice = sched_rr_timeslice; | |
2170 | p->rt.on_rq = 0; | |
2171 | p->rt.on_list = 0; | |
2172 | ||
2173 | #ifdef CONFIG_PREEMPT_NOTIFIERS | |
2174 | INIT_HLIST_HEAD(&p->preempt_notifiers); | |
2175 | #endif | |
2176 | ||
2177 | #ifdef CONFIG_NUMA_BALANCING | |
2178 | if (p->mm && atomic_read(&p->mm->mm_users) == 1) { | |
2179 | p->mm->numa_next_scan = jiffies + msecs_to_jiffies(sysctl_numa_balancing_scan_delay); | |
2180 | p->mm->numa_scan_seq = 0; | |
2181 | } | |
2182 | ||
2183 | if (clone_flags & CLONE_VM) | |
2184 | p->numa_preferred_nid = current->numa_preferred_nid; | |
2185 | else | |
2186 | p->numa_preferred_nid = -1; | |
2187 | ||
2188 | p->node_stamp = 0ULL; | |
2189 | p->numa_scan_seq = p->mm ? p->mm->numa_scan_seq : 0; | |
2190 | p->numa_scan_period = sysctl_numa_balancing_scan_delay; | |
2191 | p->numa_work.next = &p->numa_work; | |
2192 | p->numa_faults = NULL; | |
2193 | p->last_task_numa_placement = 0; | |
2194 | p->last_sum_exec_runtime = 0; | |
2195 | ||
2196 | p->numa_group = NULL; | |
2197 | #endif /* CONFIG_NUMA_BALANCING */ | |
2198 | } | |
2199 | ||
2200 | DEFINE_STATIC_KEY_FALSE(sched_numa_balancing); | |
2201 | ||
2202 | #ifdef CONFIG_NUMA_BALANCING | |
2203 | ||
2204 | void set_numabalancing_state(bool enabled) | |
2205 | { | |
2206 | if (enabled) | |
2207 | static_branch_enable(&sched_numa_balancing); | |
2208 | else | |
2209 | static_branch_disable(&sched_numa_balancing); | |
2210 | } | |
2211 | ||
2212 | #ifdef CONFIG_PROC_SYSCTL | |
2213 | int sysctl_numa_balancing(struct ctl_table *table, int write, | |
2214 | void __user *buffer, size_t *lenp, loff_t *ppos) | |
2215 | { | |
2216 | struct ctl_table t; | |
2217 | int err; | |
2218 | int state = static_branch_likely(&sched_numa_balancing); | |
2219 | ||
2220 | if (write && !capable(CAP_SYS_ADMIN)) | |
2221 | return -EPERM; | |
2222 | ||
2223 | t = *table; | |
2224 | t.data = &state; | |
2225 | err = proc_dointvec_minmax(&t, write, buffer, lenp, ppos); | |
2226 | if (err < 0) | |
2227 | return err; | |
2228 | if (write) | |
2229 | set_numabalancing_state(state); | |
2230 | return err; | |
2231 | } | |
2232 | #endif | |
2233 | #endif | |
2234 | ||
2235 | #ifdef CONFIG_SCHEDSTATS | |
2236 | ||
2237 | DEFINE_STATIC_KEY_FALSE(sched_schedstats); | |
2238 | static bool __initdata __sched_schedstats = false; | |
2239 | ||
2240 | static void set_schedstats(bool enabled) | |
2241 | { | |
2242 | if (enabled) | |
2243 | static_branch_enable(&sched_schedstats); | |
2244 | else | |
2245 | static_branch_disable(&sched_schedstats); | |
2246 | } | |
2247 | ||
2248 | void force_schedstat_enabled(void) | |
2249 | { | |
2250 | if (!schedstat_enabled()) { | |
2251 | pr_info("kernel profiling enabled schedstats, disable via kernel.sched_schedstats.\n"); | |
2252 | static_branch_enable(&sched_schedstats); | |
2253 | } | |
2254 | } | |
2255 | ||
2256 | static int __init setup_schedstats(char *str) | |
2257 | { | |
2258 | int ret = 0; | |
2259 | if (!str) | |
2260 | goto out; | |
2261 | ||
2262 | /* | |
2263 | * This code is called before jump labels have been set up, so we can't | |
2264 | * change the static branch directly just yet. Instead set a temporary | |
2265 | * variable so init_schedstats() can do it later. | |
2266 | */ | |
2267 | if (!strcmp(str, "enable")) { | |
2268 | __sched_schedstats = true; | |
2269 | ret = 1; | |
2270 | } else if (!strcmp(str, "disable")) { | |
2271 | __sched_schedstats = false; | |
2272 | ret = 1; | |
2273 | } | |
2274 | out: | |
2275 | if (!ret) | |
2276 | pr_warn("Unable to parse schedstats=\n"); | |
2277 | ||
2278 | return ret; | |
2279 | } | |
2280 | __setup("schedstats=", setup_schedstats); | |
2281 | ||
2282 | static void __init init_schedstats(void) | |
2283 | { | |
2284 | set_schedstats(__sched_schedstats); | |
2285 | } | |
2286 | ||
2287 | #ifdef CONFIG_PROC_SYSCTL | |
2288 | int sysctl_schedstats(struct ctl_table *table, int write, | |
2289 | void __user *buffer, size_t *lenp, loff_t *ppos) | |
2290 | { | |
2291 | struct ctl_table t; | |
2292 | int err; | |
2293 | int state = static_branch_likely(&sched_schedstats); | |
2294 | ||
2295 | if (write && !capable(CAP_SYS_ADMIN)) | |
2296 | return -EPERM; | |
2297 | ||
2298 | t = *table; | |
2299 | t.data = &state; | |
2300 | err = proc_dointvec_minmax(&t, write, buffer, lenp, ppos); | |
2301 | if (err < 0) | |
2302 | return err; | |
2303 | if (write) | |
2304 | set_schedstats(state); | |
2305 | return err; | |
2306 | } | |
2307 | #endif /* CONFIG_PROC_SYSCTL */ | |
2308 | #else /* !CONFIG_SCHEDSTATS */ | |
2309 | static inline void init_schedstats(void) {} | |
2310 | #endif /* CONFIG_SCHEDSTATS */ | |
2311 | ||
2312 | /* | |
2313 | * fork()/clone()-time setup: | |
2314 | */ | |
2315 | int sched_fork(unsigned long clone_flags, struct task_struct *p) | |
2316 | { | |
2317 | unsigned long flags; | |
2318 | int cpu = get_cpu(); | |
2319 | ||
2320 | __sched_fork(clone_flags, p); | |
2321 | /* | |
2322 | * We mark the process as NEW here. This guarantees that | |
2323 | * nobody will actually run it, and a signal or other external | |
2324 | * event cannot wake it up and insert it on the runqueue either. | |
2325 | */ | |
2326 | p->state = TASK_NEW; | |
2327 | ||
2328 | /* | |
2329 | * Make sure we do not leak PI boosting priority to the child. | |
2330 | */ | |
2331 | p->prio = current->normal_prio; | |
2332 | ||
2333 | /* | |
2334 | * Revert to default priority/policy on fork if requested. | |
2335 | */ | |
2336 | if (unlikely(p->sched_reset_on_fork)) { | |
2337 | if (task_has_dl_policy(p) || task_has_rt_policy(p)) { | |
2338 | p->policy = SCHED_NORMAL; | |
2339 | p->static_prio = NICE_TO_PRIO(0); | |
2340 | p->rt_priority = 0; | |
2341 | } else if (PRIO_TO_NICE(p->static_prio) < 0) | |
2342 | p->static_prio = NICE_TO_PRIO(0); | |
2343 | ||
2344 | p->prio = p->normal_prio = __normal_prio(p); | |
2345 | set_load_weight(p, false); | |
2346 | ||
2347 | /* | |
2348 | * We don't need the reset flag anymore after the fork. It has | |
2349 | * fulfilled its duty: | |
2350 | */ | |
2351 | p->sched_reset_on_fork = 0; | |
2352 | } | |
2353 | ||
2354 | if (dl_prio(p->prio)) { | |
2355 | put_cpu(); | |
2356 | return -EAGAIN; | |
2357 | } else if (rt_prio(p->prio)) { | |
2358 | p->sched_class = &rt_sched_class; | |
2359 | } else { | |
2360 | p->sched_class = &fair_sched_class; | |
2361 | } | |
2362 | ||
2363 | init_entity_runnable_average(&p->se); | |
2364 | ||
2365 | /* | |
2366 | * The child is not yet in the pid-hash so no cgroup attach races, | |
2367 | * and the cgroup is pinned to this child due to cgroup_fork() | |
2368 | * is ran before sched_fork(). | |
2369 | * | |
2370 | * Silence PROVE_RCU. | |
2371 | */ | |
2372 | raw_spin_lock_irqsave(&p->pi_lock, flags); | |
2373 | /* | |
2374 | * We're setting the CPU for the first time, we don't migrate, | |
2375 | * so use __set_task_cpu(). | |
2376 | */ | |
2377 | __set_task_cpu(p, cpu); | |
2378 | if (p->sched_class->task_fork) | |
2379 | p->sched_class->task_fork(p); | |
2380 | raw_spin_unlock_irqrestore(&p->pi_lock, flags); | |
2381 | ||
2382 | #ifdef CONFIG_SCHED_INFO | |
2383 | if (likely(sched_info_on())) | |
2384 | memset(&p->sched_info, 0, sizeof(p->sched_info)); | |
2385 | #endif | |
2386 | #if defined(CONFIG_SMP) | |
2387 | p->on_cpu = 0; | |
2388 | #endif | |
2389 | init_task_preempt_count(p); | |
2390 | #ifdef CONFIG_SMP | |
2391 | plist_node_init(&p->pushable_tasks, MAX_PRIO); | |
2392 | RB_CLEAR_NODE(&p->pushable_dl_tasks); | |
2393 | #endif | |
2394 | ||
2395 | put_cpu(); | |
2396 | return 0; | |
2397 | } | |
2398 | ||
2399 | unsigned long to_ratio(u64 period, u64 runtime) | |
2400 | { | |
2401 | if (runtime == RUNTIME_INF) | |
2402 | return BW_UNIT; | |
2403 | ||
2404 | /* | |
2405 | * Doing this here saves a lot of checks in all | |
2406 | * the calling paths, and returning zero seems | |
2407 | * safe for them anyway. | |
2408 | */ | |
2409 | if (period == 0) | |
2410 | return 0; | |
2411 | ||
2412 | return div64_u64(runtime << BW_SHIFT, period); | |
2413 | } | |
2414 | ||
2415 | /* | |
2416 | * wake_up_new_task - wake up a newly created task for the first time. | |
2417 | * | |
2418 | * This function will do some initial scheduler statistics housekeeping | |
2419 | * that must be done for every newly created context, then puts the task | |
2420 | * on the runqueue and wakes it. | |
2421 | */ | |
2422 | void wake_up_new_task(struct task_struct *p) | |
2423 | { | |
2424 | struct rq_flags rf; | |
2425 | struct rq *rq; | |
2426 | ||
2427 | raw_spin_lock_irqsave(&p->pi_lock, rf.flags); | |
2428 | p->state = TASK_RUNNING; | |
2429 | #ifdef CONFIG_SMP | |
2430 | /* | |
2431 | * Fork balancing, do it here and not earlier because: | |
2432 | * - cpus_allowed can change in the fork path | |
2433 | * - any previously selected CPU might disappear through hotplug | |
2434 | * | |
2435 | * Use __set_task_cpu() to avoid calling sched_class::migrate_task_rq, | |
2436 | * as we're not fully set-up yet. | |
2437 | */ | |
2438 | p->recent_used_cpu = task_cpu(p); | |
2439 | __set_task_cpu(p, select_task_rq(p, task_cpu(p), SD_BALANCE_FORK, 0)); | |
2440 | #endif | |
2441 | rq = __task_rq_lock(p, &rf); | |
2442 | update_rq_clock(rq); | |
2443 | post_init_entity_util_avg(&p->se); | |
2444 | ||
2445 | activate_task(rq, p, ENQUEUE_NOCLOCK); | |
2446 | p->on_rq = TASK_ON_RQ_QUEUED; | |
2447 | trace_sched_wakeup_new(p); | |
2448 | check_preempt_curr(rq, p, WF_FORK); | |
2449 | #ifdef CONFIG_SMP | |
2450 | if (p->sched_class->task_woken) { | |
2451 | /* | |
2452 | * Nothing relies on rq->lock after this, so its fine to | |
2453 | * drop it. | |
2454 | */ | |
2455 | rq_unpin_lock(rq, &rf); | |
2456 | p->sched_class->task_woken(rq, p); | |
2457 | rq_repin_lock(rq, &rf); | |
2458 | } | |
2459 | #endif | |
2460 | task_rq_unlock(rq, p, &rf); | |
2461 | } | |
2462 | ||
2463 | #ifdef CONFIG_PREEMPT_NOTIFIERS | |
2464 | ||
2465 | static struct static_key preempt_notifier_key = STATIC_KEY_INIT_FALSE; | |
2466 | ||
2467 | void preempt_notifier_inc(void) | |
2468 | { | |
2469 | static_key_slow_inc(&preempt_notifier_key); | |
2470 | } | |
2471 | EXPORT_SYMBOL_GPL(preempt_notifier_inc); | |
2472 | ||
2473 | void preempt_notifier_dec(void) | |
2474 | { | |
2475 | static_key_slow_dec(&preempt_notifier_key); | |
2476 | } | |
2477 | EXPORT_SYMBOL_GPL(preempt_notifier_dec); | |
2478 | ||
2479 | /** | |
2480 | * preempt_notifier_register - tell me when current is being preempted & rescheduled | |
2481 | * @notifier: notifier struct to register | |
2482 | */ | |
2483 | void preempt_notifier_register(struct preempt_notifier *notifier) | |
2484 | { | |
2485 | if (!static_key_false(&preempt_notifier_key)) | |
2486 | WARN(1, "registering preempt_notifier while notifiers disabled\n"); | |
2487 | ||
2488 | hlist_add_head(¬ifier->link, ¤t->preempt_notifiers); | |
2489 | } | |
2490 | EXPORT_SYMBOL_GPL(preempt_notifier_register); | |
2491 | ||
2492 | /** | |
2493 | * preempt_notifier_unregister - no longer interested in preemption notifications | |
2494 | * @notifier: notifier struct to unregister | |
2495 | * | |
2496 | * This is *not* safe to call from within a preemption notifier. | |
2497 | */ | |
2498 | void preempt_notifier_unregister(struct preempt_notifier *notifier) | |
2499 | { | |
2500 | hlist_del(¬ifier->link); | |
2501 | } | |
2502 | EXPORT_SYMBOL_GPL(preempt_notifier_unregister); | |
2503 | ||
2504 | static void __fire_sched_in_preempt_notifiers(struct task_struct *curr) | |
2505 | { | |
2506 | struct preempt_notifier *notifier; | |
2507 | ||
2508 | hlist_for_each_entry(notifier, &curr->preempt_notifiers, link) | |
2509 | notifier->ops->sched_in(notifier, raw_smp_processor_id()); | |
2510 | } | |
2511 | ||
2512 | static __always_inline void fire_sched_in_preempt_notifiers(struct task_struct *curr) | |
2513 | { | |
2514 | if (static_key_false(&preempt_notifier_key)) | |
2515 | __fire_sched_in_preempt_notifiers(curr); | |
2516 | } | |
2517 | ||
2518 | static void | |
2519 | __fire_sched_out_preempt_notifiers(struct task_struct *curr, | |
2520 | struct task_struct *next) | |
2521 | { | |
2522 | struct preempt_notifier *notifier; | |
2523 | ||
2524 | hlist_for_each_entry(notifier, &curr->preempt_notifiers, link) | |
2525 | notifier->ops->sched_out(notifier, next); | |
2526 | } | |
2527 | ||
2528 | static __always_inline void | |
2529 | fire_sched_out_preempt_notifiers(struct task_struct *curr, | |
2530 | struct task_struct *next) | |
2531 | { | |
2532 | if (static_key_false(&preempt_notifier_key)) | |
2533 | __fire_sched_out_preempt_notifiers(curr, next); | |
2534 | } | |
2535 | ||
2536 | #else /* !CONFIG_PREEMPT_NOTIFIERS */ | |
2537 | ||
2538 | static inline void fire_sched_in_preempt_notifiers(struct task_struct *curr) | |
2539 | { | |
2540 | } | |
2541 | ||
2542 | static inline void | |
2543 | fire_sched_out_preempt_notifiers(struct task_struct *curr, | |
2544 | struct task_struct *next) | |
2545 | { | |
2546 | } | |
2547 | ||
2548 | #endif /* CONFIG_PREEMPT_NOTIFIERS */ | |
2549 | ||
2550 | static inline void prepare_task(struct task_struct *next) | |
2551 | { | |
2552 | #ifdef CONFIG_SMP | |
2553 | /* | |
2554 | * Claim the task as running, we do this before switching to it | |
2555 | * such that any running task will have this set. | |
2556 | */ | |
2557 | next->on_cpu = 1; | |
2558 | #endif | |
2559 | } | |
2560 | ||
2561 | static inline void finish_task(struct task_struct *prev) | |
2562 | { | |
2563 | #ifdef CONFIG_SMP | |
2564 | /* | |
2565 | * After ->on_cpu is cleared, the task can be moved to a different CPU. | |
2566 | * We must ensure this doesn't happen until the switch is completely | |
2567 | * finished. | |
2568 | * | |
2569 | * In particular, the load of prev->state in finish_task_switch() must | |
2570 | * happen before this. | |
2571 | * | |
2572 | * Pairs with the smp_cond_load_acquire() in try_to_wake_up(). | |
2573 | */ | |
2574 | smp_store_release(&prev->on_cpu, 0); | |
2575 | #endif | |
2576 | } | |
2577 | ||
2578 | static inline void | |
2579 | prepare_lock_switch(struct rq *rq, struct task_struct *next, struct rq_flags *rf) | |
2580 | { | |
2581 | /* | |
2582 | * Since the runqueue lock will be released by the next | |
2583 | * task (which is an invalid locking op but in the case | |
2584 | * of the scheduler it's an obvious special-case), so we | |
2585 | * do an early lockdep release here: | |
2586 | */ | |
2587 | rq_unpin_lock(rq, rf); | |
2588 | spin_release(&rq->lock.dep_map, 1, _THIS_IP_); | |
2589 | #ifdef CONFIG_DEBUG_SPINLOCK | |
2590 | /* this is a valid case when another task releases the spinlock */ | |
2591 | rq->lock.owner = next; | |
2592 | #endif | |
2593 | } | |
2594 | ||
2595 | static inline void finish_lock_switch(struct rq *rq) | |
2596 | { | |
2597 | /* | |
2598 | * If we are tracking spinlock dependencies then we have to | |
2599 | * fix up the runqueue lock - which gets 'carried over' from | |
2600 | * prev into current: | |
2601 | */ | |
2602 | spin_acquire(&rq->lock.dep_map, 0, 0, _THIS_IP_); | |
2603 | raw_spin_unlock_irq(&rq->lock); | |
2604 | } | |
2605 | ||
2606 | /* | |
2607 | * NOP if the arch has not defined these: | |
2608 | */ | |
2609 | ||
2610 | #ifndef prepare_arch_switch | |
2611 | # define prepare_arch_switch(next) do { } while (0) | |
2612 | #endif | |
2613 | ||
2614 | #ifndef finish_arch_post_lock_switch | |
2615 | # define finish_arch_post_lock_switch() do { } while (0) | |
2616 | #endif | |
2617 | ||
2618 | /** | |
2619 | * prepare_task_switch - prepare to switch tasks | |
2620 | * @rq: the runqueue preparing to switch | |
2621 | * @prev: the current task that is being switched out | |
2622 | * @next: the task we are going to switch to. | |
2623 | * | |
2624 | * This is called with the rq lock held and interrupts off. It must | |
2625 | * be paired with a subsequent finish_task_switch after the context | |
2626 | * switch. | |
2627 | * | |
2628 | * prepare_task_switch sets up locking and calls architecture specific | |
2629 | * hooks. | |
2630 | */ | |
2631 | static inline void | |
2632 | prepare_task_switch(struct rq *rq, struct task_struct *prev, | |
2633 | struct task_struct *next) | |
2634 | { | |
2635 | sched_info_switch(rq, prev, next); | |
2636 | perf_event_task_sched_out(prev, next); | |
2637 | fire_sched_out_preempt_notifiers(prev, next); | |
2638 | prepare_task(next); | |
2639 | prepare_arch_switch(next); | |
2640 | } | |
2641 | ||
2642 | /** | |
2643 | * finish_task_switch - clean up after a task-switch | |
2644 | * @prev: the thread we just switched away from. | |
2645 | * | |
2646 | * finish_task_switch must be called after the context switch, paired | |
2647 | * with a prepare_task_switch call before the context switch. | |
2648 | * finish_task_switch will reconcile locking set up by prepare_task_switch, | |
2649 | * and do any other architecture-specific cleanup actions. | |
2650 | * | |
2651 | * Note that we may have delayed dropping an mm in context_switch(). If | |
2652 | * so, we finish that here outside of the runqueue lock. (Doing it | |
2653 | * with the lock held can cause deadlocks; see schedule() for | |
2654 | * details.) | |
2655 | * | |
2656 | * The context switch have flipped the stack from under us and restored the | |
2657 | * local variables which were saved when this task called schedule() in the | |
2658 | * past. prev == current is still correct but we need to recalculate this_rq | |
2659 | * because prev may have moved to another CPU. | |
2660 | */ | |
2661 | static struct rq *finish_task_switch(struct task_struct *prev) | |
2662 | __releases(rq->lock) | |
2663 | { | |
2664 | struct rq *rq = this_rq(); | |
2665 | struct mm_struct *mm = rq->prev_mm; | |
2666 | long prev_state; | |
2667 | ||
2668 | /* | |
2669 | * The previous task will have left us with a preempt_count of 2 | |
2670 | * because it left us after: | |
2671 | * | |
2672 | * schedule() | |
2673 | * preempt_disable(); // 1 | |
2674 | * __schedule() | |
2675 | * raw_spin_lock_irq(&rq->lock) // 2 | |
2676 | * | |
2677 | * Also, see FORK_PREEMPT_COUNT. | |
2678 | */ | |
2679 | if (WARN_ONCE(preempt_count() != 2*PREEMPT_DISABLE_OFFSET, | |
2680 | "corrupted preempt_count: %s/%d/0x%x\n", | |
2681 | current->comm, current->pid, preempt_count())) | |
2682 | preempt_count_set(FORK_PREEMPT_COUNT); | |
2683 | ||
2684 | rq->prev_mm = NULL; | |
2685 | ||
2686 | /* | |
2687 | * A task struct has one reference for the use as "current". | |
2688 | * If a task dies, then it sets TASK_DEAD in tsk->state and calls | |
2689 | * schedule one last time. The schedule call will never return, and | |
2690 | * the scheduled task must drop that reference. | |
2691 | * | |
2692 | * We must observe prev->state before clearing prev->on_cpu (in | |
2693 | * finish_task), otherwise a concurrent wakeup can get prev | |
2694 | * running on another CPU and we could rave with its RUNNING -> DEAD | |
2695 | * transition, resulting in a double drop. | |
2696 | */ | |
2697 | prev_state = prev->state; | |
2698 | vtime_task_switch(prev); | |
2699 | perf_event_task_sched_in(prev, current); | |
2700 | finish_task(prev); | |
2701 | finish_lock_switch(rq); | |
2702 | finish_arch_post_lock_switch(); | |
2703 | ||
2704 | fire_sched_in_preempt_notifiers(current); | |
2705 | /* | |
2706 | * When switching through a kernel thread, the loop in | |
2707 | * membarrier_{private,global}_expedited() may have observed that | |
2708 | * kernel thread and not issued an IPI. It is therefore possible to | |
2709 | * schedule between user->kernel->user threads without passing though | |
2710 | * switch_mm(). Membarrier requires a barrier after storing to | |
2711 | * rq->curr, before returning to userspace, so provide them here: | |
2712 | * | |
2713 | * - a full memory barrier for {PRIVATE,GLOBAL}_EXPEDITED, implicitly | |
2714 | * provided by mmdrop(), | |
2715 | * - a sync_core for SYNC_CORE. | |
2716 | */ | |
2717 | if (mm) { | |
2718 | membarrier_mm_sync_core_before_usermode(mm); | |
2719 | mmdrop(mm); | |
2720 | } | |
2721 | if (unlikely(prev_state == TASK_DEAD)) { | |
2722 | if (prev->sched_class->task_dead) | |
2723 | prev->sched_class->task_dead(prev); | |
2724 | ||
2725 | /* | |
2726 | * Remove function-return probe instances associated with this | |
2727 | * task and put them back on the free list. | |
2728 | */ | |
2729 | kprobe_flush_task(prev); | |
2730 | ||
2731 | /* Task is done with its stack. */ | |
2732 | put_task_stack(prev); | |
2733 | ||
2734 | put_task_struct(prev); | |
2735 | } | |
2736 | ||
2737 | tick_nohz_task_switch(); | |
2738 | return rq; | |
2739 | } | |
2740 | ||
2741 | #ifdef CONFIG_SMP | |
2742 | ||
2743 | /* rq->lock is NOT held, but preemption is disabled */ | |
2744 | static void __balance_callback(struct rq *rq) | |
2745 | { | |
2746 | struct callback_head *head, *next; | |
2747 | void (*func)(struct rq *rq); | |
2748 | unsigned long flags; | |
2749 | ||
2750 | raw_spin_lock_irqsave(&rq->lock, flags); | |
2751 | head = rq->balance_callback; | |
2752 | rq->balance_callback = NULL; | |
2753 | while (head) { | |
2754 | func = (void (*)(struct rq *))head->func; | |
2755 | next = head->next; | |
2756 | head->next = NULL; | |
2757 | head = next; | |
2758 | ||
2759 | func(rq); | |
2760 | } | |
2761 | raw_spin_unlock_irqrestore(&rq->lock, flags); | |
2762 | } | |
2763 | ||
2764 | static inline void balance_callback(struct rq *rq) | |
2765 | { | |
2766 | if (unlikely(rq->balance_callback)) | |
2767 | __balance_callback(rq); | |
2768 | } | |
2769 | ||
2770 | #else | |
2771 | ||
2772 | static inline void balance_callback(struct rq *rq) | |
2773 | { | |
2774 | } | |
2775 | ||
2776 | #endif | |
2777 | ||
2778 | /** | |
2779 | * schedule_tail - first thing a freshly forked thread must call. | |
2780 | * @prev: the thread we just switched away from. | |
2781 | */ | |
2782 | asmlinkage __visible void schedule_tail(struct task_struct *prev) | |
2783 | __releases(rq->lock) | |
2784 | { | |
2785 | struct rq *rq; | |
2786 | ||
2787 | /* | |
2788 | * New tasks start with FORK_PREEMPT_COUNT, see there and | |
2789 | * finish_task_switch() for details. | |
2790 | * | |
2791 | * finish_task_switch() will drop rq->lock() and lower preempt_count | |
2792 | * and the preempt_enable() will end up enabling preemption (on | |
2793 | * PREEMPT_COUNT kernels). | |
2794 | */ | |
2795 | ||
2796 | rq = finish_task_switch(prev); | |
2797 | balance_callback(rq); | |
2798 | preempt_enable(); | |
2799 | ||
2800 | if (current->set_child_tid) | |
2801 | put_user(task_pid_vnr(current), current->set_child_tid); | |
2802 | } | |
2803 | ||
2804 | /* | |
2805 | * context_switch - switch to the new MM and the new thread's register state. | |
2806 | */ | |
2807 | static __always_inline struct rq * | |
2808 | context_switch(struct rq *rq, struct task_struct *prev, | |
2809 | struct task_struct *next, struct rq_flags *rf) | |
2810 | { | |
2811 | struct mm_struct *mm, *oldmm; | |
2812 | ||
2813 | prepare_task_switch(rq, prev, next); | |
2814 | ||
2815 | mm = next->mm; | |
2816 | oldmm = prev->active_mm; | |
2817 | /* | |
2818 | * For paravirt, this is coupled with an exit in switch_to to | |
2819 | * combine the page table reload and the switch backend into | |
2820 | * one hypercall. | |
2821 | */ | |
2822 | arch_start_context_switch(prev); | |
2823 | ||
2824 | /* | |
2825 | * If mm is non-NULL, we pass through switch_mm(). If mm is | |
2826 | * NULL, we will pass through mmdrop() in finish_task_switch(). | |
2827 | * Both of these contain the full memory barrier required by | |
2828 | * membarrier after storing to rq->curr, before returning to | |
2829 | * user-space. | |
2830 | */ | |
2831 | if (!mm) { | |
2832 | next->active_mm = oldmm; | |
2833 | mmgrab(oldmm); | |
2834 | enter_lazy_tlb(oldmm, next); | |
2835 | } else | |
2836 | switch_mm_irqs_off(oldmm, mm, next); | |
2837 | ||
2838 | if (!prev->mm) { | |
2839 | prev->active_mm = NULL; | |
2840 | rq->prev_mm = oldmm; | |
2841 | } | |
2842 | ||
2843 | rq->clock_update_flags &= ~(RQCF_ACT_SKIP|RQCF_REQ_SKIP); | |
2844 | ||
2845 | prepare_lock_switch(rq, next, rf); | |
2846 | ||
2847 | /* Here we just switch the register state and the stack. */ | |
2848 | switch_to(prev, next, prev); | |
2849 | barrier(); | |
2850 | ||
2851 | return finish_task_switch(prev); | |
2852 | } | |
2853 | ||
2854 | /* | |
2855 | * nr_running and nr_context_switches: | |
2856 | * | |
2857 | * externally visible scheduler statistics: current number of runnable | |
2858 | * threads, total number of context switches performed since bootup. | |
2859 | */ | |
2860 | unsigned long nr_running(void) | |
2861 | { | |
2862 | unsigned long i, sum = 0; | |
2863 | ||
2864 | for_each_online_cpu(i) | |
2865 | sum += cpu_rq(i)->nr_running; | |
2866 | ||
2867 | return sum; | |
2868 | } | |
2869 | ||
2870 | /* | |
2871 | * Check if only the current task is running on the CPU. | |
2872 | * | |
2873 | * Caution: this function does not check that the caller has disabled | |
2874 | * preemption, thus the result might have a time-of-check-to-time-of-use | |
2875 | * race. The caller is responsible to use it correctly, for example: | |
2876 | * | |
2877 | * - from a non-preemptable section (of course) | |
2878 | * | |
2879 | * - from a thread that is bound to a single CPU | |
2880 | * | |
2881 | * - in a loop with very short iterations (e.g. a polling loop) | |
2882 | */ | |
2883 | bool single_task_running(void) | |
2884 | { | |
2885 | return raw_rq()->nr_running == 1; | |
2886 | } | |
2887 | EXPORT_SYMBOL(single_task_running); | |
2888 | ||
2889 | unsigned long long nr_context_switches(void) | |
2890 | { | |
2891 | int i; | |
2892 | unsigned long long sum = 0; | |
2893 | ||
2894 | for_each_possible_cpu(i) | |
2895 | sum += cpu_rq(i)->nr_switches; | |
2896 | ||
2897 | return sum; | |
2898 | } | |
2899 | ||
2900 | /* | |
2901 | * IO-wait accounting, and how its mostly bollocks (on SMP). | |
2902 | * | |
2903 | * The idea behind IO-wait account is to account the idle time that we could | |
2904 | * have spend running if it were not for IO. That is, if we were to improve the | |
2905 | * storage performance, we'd have a proportional reduction in IO-wait time. | |
2906 | * | |
2907 | * This all works nicely on UP, where, when a task blocks on IO, we account | |
2908 | * idle time as IO-wait, because if the storage were faster, it could've been | |
2909 | * running and we'd not be idle. | |
2910 | * | |
2911 | * This has been extended to SMP, by doing the same for each CPU. This however | |
2912 | * is broken. | |
2913 | * | |
2914 | * Imagine for instance the case where two tasks block on one CPU, only the one | |
2915 | * CPU will have IO-wait accounted, while the other has regular idle. Even | |
2916 | * though, if the storage were faster, both could've ran at the same time, | |
2917 | * utilising both CPUs. | |
2918 | * | |
2919 | * This means, that when looking globally, the current IO-wait accounting on | |
2920 | * SMP is a lower bound, by reason of under accounting. | |
2921 | * | |
2922 | * Worse, since the numbers are provided per CPU, they are sometimes | |
2923 | * interpreted per CPU, and that is nonsensical. A blocked task isn't strictly | |
2924 | * associated with any one particular CPU, it can wake to another CPU than it | |
2925 | * blocked on. This means the per CPU IO-wait number is meaningless. | |
2926 | * | |
2927 | * Task CPU affinities can make all that even more 'interesting'. | |
2928 | */ | |
2929 | ||
2930 | unsigned long nr_iowait(void) | |
2931 | { | |
2932 | unsigned long i, sum = 0; | |
2933 | ||
2934 | for_each_possible_cpu(i) | |
2935 | sum += atomic_read(&cpu_rq(i)->nr_iowait); | |
2936 | ||
2937 | return sum; | |
2938 | } | |
2939 | ||
2940 | /* | |
2941 | * Consumers of these two interfaces, like for example the cpufreq menu | |
2942 | * governor are using nonsensical data. Boosting frequency for a CPU that has | |
2943 | * IO-wait which might not even end up running the task when it does become | |
2944 | * runnable. | |
2945 | */ | |
2946 | ||
2947 | unsigned long nr_iowait_cpu(int cpu) | |
2948 | { | |
2949 | struct rq *this = cpu_rq(cpu); | |
2950 | return atomic_read(&this->nr_iowait); | |
2951 | } | |
2952 | ||
2953 | void get_iowait_load(unsigned long *nr_waiters, unsigned long *load) | |
2954 | { | |
2955 | struct rq *rq = this_rq(); | |
2956 | *nr_waiters = atomic_read(&rq->nr_iowait); | |
2957 | *load = rq->load.weight; | |
2958 | } | |
2959 | ||
2960 | #ifdef CONFIG_SMP | |
2961 | ||
2962 | /* | |
2963 | * sched_exec - execve() is a valuable balancing opportunity, because at | |
2964 | * this point the task has the smallest effective memory and cache footprint. | |
2965 | */ | |
2966 | void sched_exec(void) | |
2967 | { | |
2968 | struct task_struct *p = current; | |
2969 | unsigned long flags; | |
2970 | int dest_cpu; | |
2971 | ||
2972 | raw_spin_lock_irqsave(&p->pi_lock, flags); | |
2973 | dest_cpu = p->sched_class->select_task_rq(p, task_cpu(p), SD_BALANCE_EXEC, 0); | |
2974 | if (dest_cpu == smp_processor_id()) | |
2975 | goto unlock; | |
2976 | ||
2977 | if (likely(cpu_active(dest_cpu))) { | |
2978 | struct migration_arg arg = { p, dest_cpu }; | |
2979 | ||
2980 | raw_spin_unlock_irqrestore(&p->pi_lock, flags); | |
2981 | stop_one_cpu(task_cpu(p), migration_cpu_stop, &arg); | |
2982 | return; | |
2983 | } | |
2984 | unlock: | |
2985 | raw_spin_unlock_irqrestore(&p->pi_lock, flags); | |
2986 | } | |
2987 | ||
2988 | #endif | |
2989 | ||
2990 | DEFINE_PER_CPU(struct kernel_stat, kstat); | |
2991 | DEFINE_PER_CPU(struct kernel_cpustat, kernel_cpustat); | |
2992 | ||
2993 | EXPORT_PER_CPU_SYMBOL(kstat); | |
2994 | EXPORT_PER_CPU_SYMBOL(kernel_cpustat); | |
2995 | ||
2996 | /* | |
2997 | * The function fair_sched_class.update_curr accesses the struct curr | |
2998 | * and its field curr->exec_start; when called from task_sched_runtime(), | |
2999 | * we observe a high rate of cache misses in practice. | |
3000 | * Prefetching this data results in improved performance. | |
3001 | */ | |
3002 | static inline void prefetch_curr_exec_start(struct task_struct *p) | |
3003 | { | |
3004 | #ifdef CONFIG_FAIR_GROUP_SCHED | |
3005 | struct sched_entity *curr = (&p->se)->cfs_rq->curr; | |
3006 | #else | |
3007 | struct sched_entity *curr = (&task_rq(p)->cfs)->curr; | |
3008 | #endif | |
3009 | prefetch(curr); | |
3010 | prefetch(&curr->exec_start); | |
3011 | } | |
3012 | ||
3013 | /* | |
3014 | * Return accounted runtime for the task. | |
3015 | * In case the task is currently running, return the runtime plus current's | |
3016 | * pending runtime that have not been accounted yet. | |
3017 | */ | |
3018 | unsigned long long task_sched_runtime(struct task_struct *p) | |
3019 | { | |
3020 | struct rq_flags rf; | |
3021 | struct rq *rq; | |
3022 | u64 ns; | |
3023 | ||
3024 | #if defined(CONFIG_64BIT) && defined(CONFIG_SMP) | |
3025 | /* | |
3026 | * 64-bit doesn't need locks to atomically read a 64-bit value. | |
3027 | * So we have a optimization chance when the task's delta_exec is 0. | |
3028 | * Reading ->on_cpu is racy, but this is ok. | |
3029 | * | |
3030 | * If we race with it leaving CPU, we'll take a lock. So we're correct. | |
3031 | * If we race with it entering CPU, unaccounted time is 0. This is | |
3032 | * indistinguishable from the read occurring a few cycles earlier. | |
3033 | * If we see ->on_cpu without ->on_rq, the task is leaving, and has | |
3034 | * been accounted, so we're correct here as well. | |
3035 | */ | |
3036 | if (!p->on_cpu || !task_on_rq_queued(p)) | |
3037 | return p->se.sum_exec_runtime; | |
3038 | #endif | |
3039 | ||
3040 | rq = task_rq_lock(p, &rf); | |
3041 | /* | |
3042 | * Must be ->curr _and_ ->on_rq. If dequeued, we would | |
3043 | * project cycles that may never be accounted to this | |
3044 | * thread, breaking clock_gettime(). | |
3045 | */ | |
3046 | if (task_current(rq, p) && task_on_rq_queued(p)) { | |
3047 | prefetch_curr_exec_start(p); | |
3048 | update_rq_clock(rq); | |
3049 | p->sched_class->update_curr(rq); | |
3050 | } | |
3051 | ns = p->se.sum_exec_runtime; | |
3052 | task_rq_unlock(rq, p, &rf); | |
3053 | ||
3054 | return ns; | |
3055 | } | |
3056 | ||
3057 | /* | |
3058 | * This function gets called by the timer code, with HZ frequency. | |
3059 | * We call it with interrupts disabled. | |
3060 | */ | |
3061 | void scheduler_tick(void) | |
3062 | { | |
3063 | int cpu = smp_processor_id(); | |
3064 | struct rq *rq = cpu_rq(cpu); | |
3065 | struct task_struct *curr = rq->curr; | |
3066 | struct rq_flags rf; | |
3067 | ||
3068 | sched_clock_tick(); | |
3069 | ||
3070 | rq_lock(rq, &rf); | |
3071 | ||
3072 | update_rq_clock(rq); | |
3073 | curr->sched_class->task_tick(rq, curr, 0); | |
3074 | cpu_load_update_active(rq); | |
3075 | calc_global_load_tick(rq); | |
3076 | ||
3077 | rq_unlock(rq, &rf); | |
3078 | ||
3079 | perf_event_task_tick(); | |
3080 | ||
3081 | #ifdef CONFIG_SMP | |
3082 | rq->idle_balance = idle_cpu(cpu); | |
3083 | trigger_load_balance(rq); | |
3084 | #endif | |
3085 | } | |
3086 | ||
3087 | #ifdef CONFIG_NO_HZ_FULL | |
3088 | ||
3089 | struct tick_work { | |
3090 | int cpu; | |
3091 | struct delayed_work work; | |
3092 | }; | |
3093 | ||
3094 | static struct tick_work __percpu *tick_work_cpu; | |
3095 | ||
3096 | static void sched_tick_remote(struct work_struct *work) | |
3097 | { | |
3098 | struct delayed_work *dwork = to_delayed_work(work); | |
3099 | struct tick_work *twork = container_of(dwork, struct tick_work, work); | |
3100 | int cpu = twork->cpu; | |
3101 | struct rq *rq = cpu_rq(cpu); | |
3102 | struct rq_flags rf; | |
3103 | ||
3104 | /* | |
3105 | * Handle the tick only if it appears the remote CPU is running in full | |
3106 | * dynticks mode. The check is racy by nature, but missing a tick or | |
3107 | * having one too much is no big deal because the scheduler tick updates | |
3108 | * statistics and checks timeslices in a time-independent way, regardless | |
3109 | * of when exactly it is running. | |
3110 | */ | |
3111 | if (!idle_cpu(cpu) && tick_nohz_tick_stopped_cpu(cpu)) { | |
3112 | struct task_struct *curr; | |
3113 | u64 delta; | |
3114 | ||
3115 | rq_lock_irq(rq, &rf); | |
3116 | update_rq_clock(rq); | |
3117 | curr = rq->curr; | |
3118 | delta = rq_clock_task(rq) - curr->se.exec_start; | |
3119 | ||
3120 | /* | |
3121 | * Make sure the next tick runs within a reasonable | |
3122 | * amount of time. | |
3123 | */ | |
3124 | WARN_ON_ONCE(delta > (u64)NSEC_PER_SEC * 3); | |
3125 | curr->sched_class->task_tick(rq, curr, 0); | |
3126 | rq_unlock_irq(rq, &rf); | |
3127 | } | |
3128 | ||
3129 | /* | |
3130 | * Run the remote tick once per second (1Hz). This arbitrary | |
3131 | * frequency is large enough to avoid overload but short enough | |
3132 | * to keep scheduler internal stats reasonably up to date. | |
3133 | */ | |
3134 | queue_delayed_work(system_unbound_wq, dwork, HZ); | |
3135 | } | |
3136 | ||
3137 | static void sched_tick_start(int cpu) | |
3138 | { | |
3139 | struct tick_work *twork; | |
3140 | ||
3141 | if (housekeeping_cpu(cpu, HK_FLAG_TICK)) | |
3142 | return; | |
3143 | ||
3144 | WARN_ON_ONCE(!tick_work_cpu); | |
3145 | ||
3146 | twork = per_cpu_ptr(tick_work_cpu, cpu); | |
3147 | twork->cpu = cpu; | |
3148 | INIT_DELAYED_WORK(&twork->work, sched_tick_remote); | |
3149 | queue_delayed_work(system_unbound_wq, &twork->work, HZ); | |
3150 | } | |
3151 | ||
3152 | #ifdef CONFIG_HOTPLUG_CPU | |
3153 | static void sched_tick_stop(int cpu) | |
3154 | { | |
3155 | struct tick_work *twork; | |
3156 | ||
3157 | if (housekeeping_cpu(cpu, HK_FLAG_TICK)) | |
3158 | return; | |
3159 | ||
3160 | WARN_ON_ONCE(!tick_work_cpu); | |
3161 | ||
3162 | twork = per_cpu_ptr(tick_work_cpu, cpu); | |
3163 | cancel_delayed_work_sync(&twork->work); | |
3164 | } | |
3165 | #endif /* CONFIG_HOTPLUG_CPU */ | |
3166 | ||
3167 | int __init sched_tick_offload_init(void) | |
3168 | { | |
3169 | tick_work_cpu = alloc_percpu(struct tick_work); | |
3170 | BUG_ON(!tick_work_cpu); | |
3171 | ||
3172 | return 0; | |
3173 | } | |
3174 | ||
3175 | #else /* !CONFIG_NO_HZ_FULL */ | |
3176 | static inline void sched_tick_start(int cpu) { } | |
3177 | static inline void sched_tick_stop(int cpu) { } | |
3178 | #endif | |
3179 | ||
3180 | #if defined(CONFIG_PREEMPT) && (defined(CONFIG_DEBUG_PREEMPT) || \ | |
3181 | defined(CONFIG_PREEMPT_TRACER)) | |
3182 | /* | |
3183 | * If the value passed in is equal to the current preempt count | |
3184 | * then we just disabled preemption. Start timing the latency. | |
3185 | */ | |
3186 | static inline void preempt_latency_start(int val) | |
3187 | { | |
3188 | if (preempt_count() == val) { | |
3189 | unsigned long ip = get_lock_parent_ip(); | |
3190 | #ifdef CONFIG_DEBUG_PREEMPT | |
3191 | current->preempt_disable_ip = ip; | |
3192 | #endif | |
3193 | trace_preempt_off(CALLER_ADDR0, ip); | |
3194 | } | |
3195 | } | |
3196 | ||
3197 | void preempt_count_add(int val) | |
3198 | { | |
3199 | #ifdef CONFIG_DEBUG_PREEMPT | |
3200 | /* | |
3201 | * Underflow? | |
3202 | */ | |
3203 | if (DEBUG_LOCKS_WARN_ON((preempt_count() < 0))) | |
3204 | return; | |
3205 | #endif | |
3206 | __preempt_count_add(val); | |
3207 | #ifdef CONFIG_DEBUG_PREEMPT | |
3208 | /* | |
3209 | * Spinlock count overflowing soon? | |
3210 | */ | |
3211 | DEBUG_LOCKS_WARN_ON((preempt_count() & PREEMPT_MASK) >= | |
3212 | PREEMPT_MASK - 10); | |
3213 | #endif | |
3214 | preempt_latency_start(val); | |
3215 | } | |
3216 | EXPORT_SYMBOL(preempt_count_add); | |
3217 | NOKPROBE_SYMBOL(preempt_count_add); | |
3218 | ||
3219 | /* | |
3220 | * If the value passed in equals to the current preempt count | |
3221 | * then we just enabled preemption. Stop timing the latency. | |
3222 | */ | |
3223 | static inline void preempt_latency_stop(int val) | |
3224 | { | |
3225 | if (preempt_count() == val) | |
3226 | trace_preempt_on(CALLER_ADDR0, get_lock_parent_ip()); | |
3227 | } | |
3228 | ||
3229 | void preempt_count_sub(int val) | |
3230 | { | |
3231 | #ifdef CONFIG_DEBUG_PREEMPT | |
3232 | /* | |
3233 | * Underflow? | |
3234 | */ | |
3235 | if (DEBUG_LOCKS_WARN_ON(val > preempt_count())) | |
3236 | return; | |
3237 | /* | |
3238 | * Is the spinlock portion underflowing? | |
3239 | */ | |
3240 | if (DEBUG_LOCKS_WARN_ON((val < PREEMPT_MASK) && | |
3241 | !(preempt_count() & PREEMPT_MASK))) | |
3242 | return; | |
3243 | #endif | |
3244 | ||
3245 | preempt_latency_stop(val); | |
3246 | __preempt_count_sub(val); | |
3247 | } | |
3248 | EXPORT_SYMBOL(preempt_count_sub); | |
3249 | NOKPROBE_SYMBOL(preempt_count_sub); | |
3250 | ||
3251 | #else | |
3252 | static inline void preempt_latency_start(int val) { } | |
3253 | static inline void preempt_latency_stop(int val) { } | |
3254 | #endif | |
3255 | ||
3256 | static inline unsigned long get_preempt_disable_ip(struct task_struct *p) | |
3257 | { | |
3258 | #ifdef CONFIG_DEBUG_PREEMPT | |
3259 | return p->preempt_disable_ip; | |
3260 | #else | |
3261 | return 0; | |
3262 | #endif | |
3263 | } | |
3264 | ||
3265 | /* | |
3266 | * Print scheduling while atomic bug: | |
3267 | */ | |
3268 | static noinline void __schedule_bug(struct task_struct *prev) | |
3269 | { | |
3270 | /* Save this before calling printk(), since that will clobber it */ | |
3271 | unsigned long preempt_disable_ip = get_preempt_disable_ip(current); | |
3272 | ||
3273 | if (oops_in_progress) | |
3274 | return; | |
3275 | ||
3276 | printk(KERN_ERR "BUG: scheduling while atomic: %s/%d/0x%08x\n", | |
3277 | prev->comm, prev->pid, preempt_count()); | |
3278 | ||
3279 | debug_show_held_locks(prev); | |
3280 | print_modules(); | |
3281 | if (irqs_disabled()) | |
3282 | print_irqtrace_events(prev); | |
3283 | if (IS_ENABLED(CONFIG_DEBUG_PREEMPT) | |
3284 | && in_atomic_preempt_off()) { | |
3285 | pr_err("Preemption disabled at:"); | |
3286 | print_ip_sym(preempt_disable_ip); | |
3287 | pr_cont("\n"); | |
3288 | } | |
3289 | if (panic_on_warn) | |
3290 | panic("scheduling while atomic\n"); | |
3291 | ||
3292 | dump_stack(); | |
3293 | add_taint(TAINT_WARN, LOCKDEP_STILL_OK); | |
3294 | } | |
3295 | ||
3296 | /* | |
3297 | * Various schedule()-time debugging checks and statistics: | |
3298 | */ | |
3299 | static inline void schedule_debug(struct task_struct *prev) | |
3300 | { | |
3301 | #ifdef CONFIG_SCHED_STACK_END_CHECK | |
3302 | if (task_stack_end_corrupted(prev)) | |
3303 | panic("corrupted stack end detected inside scheduler\n"); | |
3304 | #endif | |
3305 | ||
3306 | if (unlikely(in_atomic_preempt_off())) { | |
3307 | __schedule_bug(prev); | |
3308 | preempt_count_set(PREEMPT_DISABLED); | |
3309 | } | |
3310 | rcu_sleep_check(); | |
3311 | ||
3312 | profile_hit(SCHED_PROFILING, __builtin_return_address(0)); | |
3313 | ||
3314 | schedstat_inc(this_rq()->sched_count); | |
3315 | } | |
3316 | ||
3317 | /* | |
3318 | * Pick up the highest-prio task: | |
3319 | */ | |
3320 | static inline struct task_struct * | |
3321 | pick_next_task(struct rq *rq, struct task_struct *prev, struct rq_flags *rf) | |
3322 | { | |
3323 | const struct sched_class *class; | |
3324 | struct task_struct *p; | |
3325 | ||
3326 | /* | |
3327 | * Optimization: we know that if all tasks are in the fair class we can | |
3328 | * call that function directly, but only if the @prev task wasn't of a | |
3329 | * higher scheduling class, because otherwise those loose the | |
3330 | * opportunity to pull in more work from other CPUs. | |
3331 | */ | |
3332 | if (likely((prev->sched_class == &idle_sched_class || | |
3333 | prev->sched_class == &fair_sched_class) && | |
3334 | rq->nr_running == rq->cfs.h_nr_running)) { | |
3335 | ||
3336 | p = fair_sched_class.pick_next_task(rq, prev, rf); | |
3337 | if (unlikely(p == RETRY_TASK)) | |
3338 | goto again; | |
3339 | ||
3340 | /* Assumes fair_sched_class->next == idle_sched_class */ | |
3341 | if (unlikely(!p)) | |
3342 | p = idle_sched_class.pick_next_task(rq, prev, rf); | |
3343 | ||
3344 | return p; | |
3345 | } | |
3346 | ||
3347 | again: | |
3348 | for_each_class(class) { | |
3349 | p = class->pick_next_task(rq, prev, rf); | |
3350 | if (p) { | |
3351 | if (unlikely(p == RETRY_TASK)) | |
3352 | goto again; | |
3353 | return p; | |
3354 | } | |
3355 | } | |
3356 | ||
3357 | /* The idle class should always have a runnable task: */ | |
3358 | BUG(); | |
3359 | } | |
3360 | ||
3361 | /* | |
3362 | * __schedule() is the main scheduler function. | |
3363 | * | |
3364 | * The main means of driving the scheduler and thus entering this function are: | |
3365 | * | |
3366 | * 1. Explicit blocking: mutex, semaphore, waitqueue, etc. | |
3367 | * | |
3368 | * 2. TIF_NEED_RESCHED flag is checked on interrupt and userspace return | |
3369 | * paths. For example, see arch/x86/entry_64.S. | |
3370 | * | |
3371 | * To drive preemption between tasks, the scheduler sets the flag in timer | |
3372 | * interrupt handler scheduler_tick(). | |
3373 | * | |
3374 | * 3. Wakeups don't really cause entry into schedule(). They add a | |
3375 | * task to the run-queue and that's it. | |
3376 | * | |
3377 | * Now, if the new task added to the run-queue preempts the current | |
3378 | * task, then the wakeup sets TIF_NEED_RESCHED and schedule() gets | |
3379 | * called on the nearest possible occasion: | |
3380 | * | |
3381 | * - If the kernel is preemptible (CONFIG_PREEMPT=y): | |
3382 | * | |
3383 | * - in syscall or exception context, at the next outmost | |
3384 | * preempt_enable(). (this might be as soon as the wake_up()'s | |
3385 | * spin_unlock()!) | |
3386 | * | |
3387 | * - in IRQ context, return from interrupt-handler to | |
3388 | * preemptible context | |
3389 | * | |
3390 | * - If the kernel is not preemptible (CONFIG_PREEMPT is not set) | |
3391 | * then at the next: | |
3392 | * | |
3393 | * - cond_resched() call | |
3394 | * - explicit schedule() call | |
3395 | * - return from syscall or exception to user-space | |
3396 | * - return from interrupt-handler to user-space | |
3397 | * | |
3398 | * WARNING: must be called with preemption disabled! | |
3399 | */ | |
3400 | static void __sched notrace __schedule(bool preempt) | |
3401 | { | |
3402 | struct task_struct *prev, *next; | |
3403 | unsigned long *switch_count; | |
3404 | struct rq_flags rf; | |
3405 | struct rq *rq; | |
3406 | int cpu; | |
3407 | ||
3408 | cpu = smp_processor_id(); | |
3409 | rq = cpu_rq(cpu); | |
3410 | prev = rq->curr; | |
3411 | ||
3412 | schedule_debug(prev); | |
3413 | ||
3414 | if (sched_feat(HRTICK)) | |
3415 | hrtick_clear(rq); | |
3416 | ||
3417 | local_irq_disable(); | |
3418 | rcu_note_context_switch(preempt); | |
3419 | ||
3420 | /* | |
3421 | * Make sure that signal_pending_state()->signal_pending() below | |
3422 | * can't be reordered with __set_current_state(TASK_INTERRUPTIBLE) | |
3423 | * done by the caller to avoid the race with signal_wake_up(). | |
3424 | * | |
3425 | * The membarrier system call requires a full memory barrier | |
3426 | * after coming from user-space, before storing to rq->curr. | |
3427 | */ | |
3428 | rq_lock(rq, &rf); | |
3429 | smp_mb__after_spinlock(); | |
3430 | ||
3431 | /* Promote REQ to ACT */ | |
3432 | rq->clock_update_flags <<= 1; | |
3433 | update_rq_clock(rq); | |
3434 | ||
3435 | switch_count = &prev->nivcsw; | |
3436 | if (!preempt && prev->state) { | |
3437 | if (unlikely(signal_pending_state(prev->state, prev))) { | |
3438 | prev->state = TASK_RUNNING; | |
3439 | } else { | |
3440 | deactivate_task(rq, prev, DEQUEUE_SLEEP | DEQUEUE_NOCLOCK); | |
3441 | prev->on_rq = 0; | |
3442 | ||
3443 | if (prev->in_iowait) { | |
3444 | atomic_inc(&rq->nr_iowait); | |
3445 | delayacct_blkio_start(); | |
3446 | } | |
3447 | ||
3448 | /* | |
3449 | * If a worker went to sleep, notify and ask workqueue | |
3450 | * whether it wants to wake up a task to maintain | |
3451 | * concurrency. | |
3452 | */ | |
3453 | if (prev->flags & PF_WQ_WORKER) { | |
3454 | struct task_struct *to_wakeup; | |
3455 | ||
3456 | to_wakeup = wq_worker_sleeping(prev); | |
3457 | if (to_wakeup) | |
3458 | try_to_wake_up_local(to_wakeup, &rf); | |
3459 | } | |
3460 | } | |
3461 | switch_count = &prev->nvcsw; | |
3462 | } | |
3463 | ||
3464 | next = pick_next_task(rq, prev, &rf); | |
3465 | clear_tsk_need_resched(prev); | |
3466 | clear_preempt_need_resched(); | |
3467 | ||
3468 | if (likely(prev != next)) { | |
3469 | rq->nr_switches++; | |
3470 | rq->curr = next; | |
3471 | /* | |
3472 | * The membarrier system call requires each architecture | |
3473 | * to have a full memory barrier after updating | |
3474 | * rq->curr, before returning to user-space. | |
3475 | * | |
3476 | * Here are the schemes providing that barrier on the | |
3477 | * various architectures: | |
3478 | * - mm ? switch_mm() : mmdrop() for x86, s390, sparc, PowerPC. | |
3479 | * switch_mm() rely on membarrier_arch_switch_mm() on PowerPC. | |
3480 | * - finish_lock_switch() for weakly-ordered | |
3481 | * architectures where spin_unlock is a full barrier, | |
3482 | * - switch_to() for arm64 (weakly-ordered, spin_unlock | |
3483 | * is a RELEASE barrier), | |
3484 | */ | |
3485 | ++*switch_count; | |
3486 | ||
3487 | trace_sched_switch(preempt, prev, next); | |
3488 | ||
3489 | /* Also unlocks the rq: */ | |
3490 | rq = context_switch(rq, prev, next, &rf); | |
3491 | } else { | |
3492 | rq->clock_update_flags &= ~(RQCF_ACT_SKIP|RQCF_REQ_SKIP); | |
3493 | rq_unlock_irq(rq, &rf); | |
3494 | } | |
3495 | ||
3496 | balance_callback(rq); | |
3497 | } | |
3498 | ||
3499 | void __noreturn do_task_dead(void) | |
3500 | { | |
3501 | /* | |
3502 | * The setting of TASK_RUNNING by try_to_wake_up() may be delayed | |
3503 | * when the following two conditions become true. | |
3504 | * - There is race condition of mmap_sem (It is acquired by | |
3505 | * exit_mm()), and | |
3506 | * - SMI occurs before setting TASK_RUNINNG. | |
3507 | * (or hypervisor of virtual machine switches to other guest) | |
3508 | * As a result, we may become TASK_RUNNING after becoming TASK_DEAD | |
3509 | * | |
3510 | * To avoid it, we have to wait for releasing tsk->pi_lock which | |
3511 | * is held by try_to_wake_up() | |
3512 | */ | |
3513 | raw_spin_lock_irq(¤t->pi_lock); | |
3514 | raw_spin_unlock_irq(¤t->pi_lock); | |
3515 | ||
3516 | /* Causes final put_task_struct in finish_task_switch(): */ | |
3517 | __set_current_state(TASK_DEAD); | |
3518 | ||
3519 | /* Tell freezer to ignore us: */ | |
3520 | current->flags |= PF_NOFREEZE; | |
3521 | ||
3522 | __schedule(false); | |
3523 | BUG(); | |
3524 | ||
3525 | /* Avoid "noreturn function does return" - but don't continue if BUG() is a NOP: */ | |
3526 | for (;;) | |
3527 | cpu_relax(); | |
3528 | } | |
3529 | ||
3530 | static inline void sched_submit_work(struct task_struct *tsk) | |
3531 | { | |
3532 | if (!tsk->state || tsk_is_pi_blocked(tsk)) | |
3533 | return; | |
3534 | /* | |
3535 | * If we are going to sleep and we have plugged IO queued, | |
3536 | * make sure to submit it to avoid deadlocks. | |
3537 | */ | |
3538 | if (blk_needs_flush_plug(tsk)) | |
3539 | blk_schedule_flush_plug(tsk); | |
3540 | } | |
3541 | ||
3542 | asmlinkage __visible void __sched schedule(void) | |
3543 | { | |
3544 | struct task_struct *tsk = current; | |
3545 | ||
3546 | sched_submit_work(tsk); | |
3547 | do { | |
3548 | preempt_disable(); | |
3549 | __schedule(false); | |
3550 | sched_preempt_enable_no_resched(); | |
3551 | } while (need_resched()); | |
3552 | } | |
3553 | EXPORT_SYMBOL(schedule); | |
3554 | ||
3555 | /* | |
3556 | * synchronize_rcu_tasks() makes sure that no task is stuck in preempted | |
3557 | * state (have scheduled out non-voluntarily) by making sure that all | |
3558 | * tasks have either left the run queue or have gone into user space. | |
3559 | * As idle tasks do not do either, they must not ever be preempted | |
3560 | * (schedule out non-voluntarily). | |
3561 | * | |
3562 | * schedule_idle() is similar to schedule_preempt_disable() except that it | |
3563 | * never enables preemption because it does not call sched_submit_work(). | |
3564 | */ | |
3565 | void __sched schedule_idle(void) | |
3566 | { | |
3567 | /* | |
3568 | * As this skips calling sched_submit_work(), which the idle task does | |
3569 | * regardless because that function is a nop when the task is in a | |
3570 | * TASK_RUNNING state, make sure this isn't used someplace that the | |
3571 | * current task can be in any other state. Note, idle is always in the | |
3572 | * TASK_RUNNING state. | |
3573 | */ | |
3574 | WARN_ON_ONCE(current->state); | |
3575 | do { | |
3576 | __schedule(false); | |
3577 | } while (need_resched()); | |
3578 | } | |
3579 | ||
3580 | #ifdef CONFIG_CONTEXT_TRACKING | |
3581 | asmlinkage __visible void __sched schedule_user(void) | |
3582 | { | |
3583 | /* | |
3584 | * If we come here after a random call to set_need_resched(), | |
3585 | * or we have been woken up remotely but the IPI has not yet arrived, | |
3586 | * we haven't yet exited the RCU idle mode. Do it here manually until | |
3587 | * we find a better solution. | |
3588 | * | |
3589 | * NB: There are buggy callers of this function. Ideally we | |
3590 | * should warn if prev_state != CONTEXT_USER, but that will trigger | |
3591 | * too frequently to make sense yet. | |
3592 | */ | |
3593 | enum ctx_state prev_state = exception_enter(); | |
3594 | schedule(); | |
3595 | exception_exit(prev_state); | |
3596 | } | |
3597 | #endif | |
3598 | ||
3599 | /** | |
3600 | * schedule_preempt_disabled - called with preemption disabled | |
3601 | * | |
3602 | * Returns with preemption disabled. Note: preempt_count must be 1 | |
3603 | */ | |
3604 | void __sched schedule_preempt_disabled(void) | |
3605 | { | |
3606 | sched_preempt_enable_no_resched(); | |
3607 | schedule(); | |
3608 | preempt_disable(); | |
3609 | } | |
3610 | ||
3611 | static void __sched notrace preempt_schedule_common(void) | |
3612 | { | |
3613 | do { | |
3614 | /* | |
3615 | * Because the function tracer can trace preempt_count_sub() | |
3616 | * and it also uses preempt_enable/disable_notrace(), if | |
3617 | * NEED_RESCHED is set, the preempt_enable_notrace() called | |
3618 | * by the function tracer will call this function again and | |
3619 | * cause infinite recursion. | |
3620 | * | |
3621 | * Preemption must be disabled here before the function | |
3622 | * tracer can trace. Break up preempt_disable() into two | |
3623 | * calls. One to disable preemption without fear of being | |
3624 | * traced. The other to still record the preemption latency, | |
3625 | * which can also be traced by the function tracer. | |
3626 | */ | |
3627 | preempt_disable_notrace(); | |
3628 | preempt_latency_start(1); | |
3629 | __schedule(true); | |
3630 | preempt_latency_stop(1); | |
3631 | preempt_enable_no_resched_notrace(); | |
3632 | ||
3633 | /* | |
3634 | * Check again in case we missed a preemption opportunity | |
3635 | * between schedule and now. | |
3636 | */ | |
3637 | } while (need_resched()); | |
3638 | } | |
3639 | ||
3640 | #ifdef CONFIG_PREEMPT | |
3641 | /* | |
3642 | * this is the entry point to schedule() from in-kernel preemption | |
3643 | * off of preempt_enable. Kernel preemptions off return from interrupt | |
3644 | * occur there and call schedule directly. | |
3645 | */ | |
3646 | asmlinkage __visible void __sched notrace preempt_schedule(void) | |
3647 | { | |
3648 | /* | |
3649 | * If there is a non-zero preempt_count or interrupts are disabled, | |
3650 | * we do not want to preempt the current task. Just return.. | |
3651 | */ | |
3652 | if (likely(!preemptible())) | |
3653 | return; | |
3654 | ||
3655 | preempt_schedule_common(); | |
3656 | } | |
3657 | NOKPROBE_SYMBOL(preempt_schedule); | |
3658 | EXPORT_SYMBOL(preempt_schedule); | |
3659 | ||
3660 | /** | |
3661 | * preempt_schedule_notrace - preempt_schedule called by tracing | |
3662 | * | |
3663 | * The tracing infrastructure uses preempt_enable_notrace to prevent | |
3664 | * recursion and tracing preempt enabling caused by the tracing | |
3665 | * infrastructure itself. But as tracing can happen in areas coming | |
3666 | * from userspace or just about to enter userspace, a preempt enable | |
3667 | * can occur before user_exit() is called. This will cause the scheduler | |
3668 | * to be called when the system is still in usermode. | |
3669 | * | |
3670 | * To prevent this, the preempt_enable_notrace will use this function | |
3671 | * instead of preempt_schedule() to exit user context if needed before | |
3672 | * calling the scheduler. | |
3673 | */ | |
3674 | asmlinkage __visible void __sched notrace preempt_schedule_notrace(void) | |
3675 | { | |
3676 | enum ctx_state prev_ctx; | |
3677 | ||
3678 | if (likely(!preemptible())) | |
3679 | return; | |
3680 | ||
3681 | do { | |
3682 | /* | |
3683 | * Because the function tracer can trace preempt_count_sub() | |
3684 | * and it also uses preempt_enable/disable_notrace(), if | |
3685 | * NEED_RESCHED is set, the preempt_enable_notrace() called | |
3686 | * by the function tracer will call this function again and | |
3687 | * cause infinite recursion. | |
3688 | * | |
3689 | * Preemption must be disabled here before the function | |
3690 | * tracer can trace. Break up preempt_disable() into two | |
3691 | * calls. One to disable preemption without fear of being | |
3692 | * traced. The other to still record the preemption latency, | |
3693 | * which can also be traced by the function tracer. | |
3694 | */ | |
3695 | preempt_disable_notrace(); | |
3696 | preempt_latency_start(1); | |
3697 | /* | |
3698 | * Needs preempt disabled in case user_exit() is traced | |
3699 | * and the tracer calls preempt_enable_notrace() causing | |
3700 | * an infinite recursion. | |
3701 | */ | |
3702 | prev_ctx = exception_enter(); | |
3703 | __schedule(true); | |
3704 | exception_exit(prev_ctx); | |
3705 | ||
3706 | preempt_latency_stop(1); | |
3707 | preempt_enable_no_resched_notrace(); | |
3708 | } while (need_resched()); | |
3709 | } | |
3710 | EXPORT_SYMBOL_GPL(preempt_schedule_notrace); | |
3711 | ||
3712 | #endif /* CONFIG_PREEMPT */ | |
3713 | ||
3714 | /* | |
3715 | * this is the entry point to schedule() from kernel preemption | |
3716 | * off of irq context. | |
3717 | * Note, that this is called and return with irqs disabled. This will | |
3718 | * protect us against recursive calling from irq. | |
3719 | */ | |
3720 | asmlinkage __visible void __sched preempt_schedule_irq(void) | |
3721 | { | |
3722 | enum ctx_state prev_state; | |
3723 | ||
3724 | /* Catch callers which need to be fixed */ | |
3725 | BUG_ON(preempt_count() || !irqs_disabled()); | |
3726 | ||
3727 | prev_state = exception_enter(); | |
3728 | ||
3729 | do { | |
3730 | preempt_disable(); | |
3731 | local_irq_enable(); | |
3732 | __schedule(true); | |
3733 | local_irq_disable(); | |
3734 | sched_preempt_enable_no_resched(); | |
3735 | } while (need_resched()); | |
3736 | ||
3737 | exception_exit(prev_state); | |
3738 | } | |
3739 | ||
3740 | int default_wake_function(wait_queue_entry_t *curr, unsigned mode, int wake_flags, | |
3741 | void *key) | |
3742 | { | |
3743 | return try_to_wake_up(curr->private, mode, wake_flags); | |
3744 | } | |
3745 | EXPORT_SYMBOL(default_wake_function); | |
3746 | ||
3747 | #ifdef CONFIG_RT_MUTEXES | |
3748 | ||
3749 | static inline int __rt_effective_prio(struct task_struct *pi_task, int prio) | |
3750 | { | |
3751 | if (pi_task) | |
3752 | prio = min(prio, pi_task->prio); | |
3753 | ||
3754 | return prio; | |
3755 | } | |
3756 | ||
3757 | static inline int rt_effective_prio(struct task_struct *p, int prio) | |
3758 | { | |
3759 | struct task_struct *pi_task = rt_mutex_get_top_task(p); | |
3760 | ||
3761 | return __rt_effective_prio(pi_task, prio); | |
3762 | } | |
3763 | ||
3764 | /* | |
3765 | * rt_mutex_setprio - set the current priority of a task | |
3766 | * @p: task to boost | |
3767 | * @pi_task: donor task | |
3768 | * | |
3769 | * This function changes the 'effective' priority of a task. It does | |
3770 | * not touch ->normal_prio like __setscheduler(). | |
3771 | * | |
3772 | * Used by the rt_mutex code to implement priority inheritance | |
3773 | * logic. Call site only calls if the priority of the task changed. | |
3774 | */ | |
3775 | void rt_mutex_setprio(struct task_struct *p, struct task_struct *pi_task) | |
3776 | { | |
3777 | int prio, oldprio, queued, running, queue_flag = | |
3778 | DEQUEUE_SAVE | DEQUEUE_MOVE | DEQUEUE_NOCLOCK; | |
3779 | const struct sched_class *prev_class; | |
3780 | struct rq_flags rf; | |
3781 | struct rq *rq; | |
3782 | ||
3783 | /* XXX used to be waiter->prio, not waiter->task->prio */ | |
3784 | prio = __rt_effective_prio(pi_task, p->normal_prio); | |
3785 | ||
3786 | /* | |
3787 | * If nothing changed; bail early. | |
3788 | */ | |
3789 | if (p->pi_top_task == pi_task && prio == p->prio && !dl_prio(prio)) | |
3790 | return; | |
3791 | ||
3792 | rq = __task_rq_lock(p, &rf); | |
3793 | update_rq_clock(rq); | |
3794 | /* | |
3795 | * Set under pi_lock && rq->lock, such that the value can be used under | |
3796 | * either lock. | |
3797 | * | |
3798 | * Note that there is loads of tricky to make this pointer cache work | |
3799 | * right. rt_mutex_slowunlock()+rt_mutex_postunlock() work together to | |
3800 | * ensure a task is de-boosted (pi_task is set to NULL) before the | |
3801 | * task is allowed to run again (and can exit). This ensures the pointer | |
3802 | * points to a blocked task -- which guaratees the task is present. | |
3803 | */ | |
3804 | p->pi_top_task = pi_task; | |
3805 | ||
3806 | /* | |
3807 | * For FIFO/RR we only need to set prio, if that matches we're done. | |
3808 | */ | |
3809 | if (prio == p->prio && !dl_prio(prio)) | |
3810 | goto out_unlock; | |
3811 | ||
3812 | /* | |
3813 | * Idle task boosting is a nono in general. There is one | |
3814 | * exception, when PREEMPT_RT and NOHZ is active: | |
3815 | * | |
3816 | * The idle task calls get_next_timer_interrupt() and holds | |
3817 | * the timer wheel base->lock on the CPU and another CPU wants | |
3818 | * to access the timer (probably to cancel it). We can safely | |
3819 | * ignore the boosting request, as the idle CPU runs this code | |
3820 | * with interrupts disabled and will complete the lock | |
3821 | * protected section without being interrupted. So there is no | |
3822 | * real need to boost. | |
3823 | */ | |
3824 | if (unlikely(p == rq->idle)) { | |
3825 | WARN_ON(p != rq->curr); | |
3826 | WARN_ON(p->pi_blocked_on); | |
3827 | goto out_unlock; | |
3828 | } | |
3829 | ||
3830 | trace_sched_pi_setprio(p, pi_task); | |
3831 | oldprio = p->prio; | |
3832 | ||
3833 | if (oldprio == prio) | |
3834 | queue_flag &= ~DEQUEUE_MOVE; | |
3835 | ||
3836 | prev_class = p->sched_class; | |
3837 | queued = task_on_rq_queued(p); | |
3838 | running = task_current(rq, p); | |
3839 | if (queued) | |
3840 | dequeue_task(rq, p, queue_flag); | |
3841 | if (running) | |
3842 | put_prev_task(rq, p); | |
3843 | ||
3844 | /* | |
3845 | * Boosting condition are: | |
3846 | * 1. -rt task is running and holds mutex A | |
3847 | * --> -dl task blocks on mutex A | |
3848 | * | |
3849 | * 2. -dl task is running and holds mutex A | |
3850 | * --> -dl task blocks on mutex A and could preempt the | |
3851 | * running task | |
3852 | */ | |
3853 | if (dl_prio(prio)) { | |
3854 | if (!dl_prio(p->normal_prio) || | |
3855 | (pi_task && dl_entity_preempt(&pi_task->dl, &p->dl))) { | |
3856 | p->dl.dl_boosted = 1; | |
3857 | queue_flag |= ENQUEUE_REPLENISH; | |
3858 | } else | |
3859 | p->dl.dl_boosted = 0; | |
3860 | p->sched_class = &dl_sched_class; | |
3861 | } else if (rt_prio(prio)) { | |
3862 | if (dl_prio(oldprio)) | |
3863 | p->dl.dl_boosted = 0; | |
3864 | if (oldprio < prio) | |
3865 | queue_flag |= ENQUEUE_HEAD; | |
3866 | p->sched_class = &rt_sched_class; | |
3867 | } else { | |
3868 | if (dl_prio(oldprio)) | |
3869 | p->dl.dl_boosted = 0; | |
3870 | if (rt_prio(oldprio)) | |
3871 | p->rt.timeout = 0; | |
3872 | p->sched_class = &fair_sched_class; | |
3873 | } | |
3874 | ||
3875 | p->prio = prio; | |
3876 | ||
3877 | if (queued) | |
3878 | enqueue_task(rq, p, queue_flag); | |
3879 | if (running) | |
3880 | set_curr_task(rq, p); | |
3881 | ||
3882 | check_class_changed(rq, p, prev_class, oldprio); | |
3883 | out_unlock: | |
3884 | /* Avoid rq from going away on us: */ | |
3885 | preempt_disable(); | |
3886 | __task_rq_unlock(rq, &rf); | |
3887 | ||
3888 | balance_callback(rq); | |
3889 | preempt_enable(); | |
3890 | } | |
3891 | #else | |
3892 | static inline int rt_effective_prio(struct task_struct *p, int prio) | |
3893 | { | |
3894 | return prio; | |
3895 | } | |
3896 | #endif | |
3897 | ||
3898 | void set_user_nice(struct task_struct *p, long nice) | |
3899 | { | |
3900 | bool queued, running; | |
3901 | int old_prio, delta; | |
3902 | struct rq_flags rf; | |
3903 | struct rq *rq; | |
3904 | ||
3905 | if (task_nice(p) == nice || nice < MIN_NICE || nice > MAX_NICE) | |
3906 | return; | |
3907 | /* | |
3908 | * We have to be careful, if called from sys_setpriority(), | |
3909 | * the task might be in the middle of scheduling on another CPU. | |
3910 | */ | |
3911 | rq = task_rq_lock(p, &rf); | |
3912 | update_rq_clock(rq); | |
3913 | ||
3914 | /* | |
3915 | * The RT priorities are set via sched_setscheduler(), but we still | |
3916 | * allow the 'normal' nice value to be set - but as expected | |
3917 | * it wont have any effect on scheduling until the task is | |
3918 | * SCHED_DEADLINE, SCHED_FIFO or SCHED_RR: | |
3919 | */ | |
3920 | if (task_has_dl_policy(p) || task_has_rt_policy(p)) { | |
3921 | p->static_prio = NICE_TO_PRIO(nice); | |
3922 | goto out_unlock; | |
3923 | } | |
3924 | queued = task_on_rq_queued(p); | |
3925 | running = task_current(rq, p); | |
3926 | if (queued) | |
3927 | dequeue_task(rq, p, DEQUEUE_SAVE | DEQUEUE_NOCLOCK); | |
3928 | if (running) | |
3929 | put_prev_task(rq, p); | |
3930 | ||
3931 | p->static_prio = NICE_TO_PRIO(nice); | |
3932 | set_load_weight(p, true); | |
3933 | old_prio = p->prio; | |
3934 | p->prio = effective_prio(p); | |
3935 | delta = p->prio - old_prio; | |
3936 | ||
3937 | if (queued) { | |
3938 | enqueue_task(rq, p, ENQUEUE_RESTORE | ENQUEUE_NOCLOCK); | |
3939 | /* | |
3940 | * If the task increased its priority or is running and | |
3941 | * lowered its priority, then reschedule its CPU: | |
3942 | */ | |
3943 | if (delta < 0 || (delta > 0 && task_running(rq, p))) | |
3944 | resched_curr(rq); | |
3945 | } | |
3946 | if (running) | |
3947 | set_curr_task(rq, p); | |
3948 | out_unlock: | |
3949 | task_rq_unlock(rq, p, &rf); | |
3950 | } | |
3951 | EXPORT_SYMBOL(set_user_nice); | |
3952 | ||
3953 | /* | |
3954 | * can_nice - check if a task can reduce its nice value | |
3955 | * @p: task | |
3956 | * @nice: nice value | |
3957 | */ | |
3958 | int can_nice(const struct task_struct *p, const int nice) | |
3959 | { | |
3960 | /* Convert nice value [19,-20] to rlimit style value [1,40]: */ | |
3961 | int nice_rlim = nice_to_rlimit(nice); | |
3962 | ||
3963 | return (nice_rlim <= task_rlimit(p, RLIMIT_NICE) || | |
3964 | capable(CAP_SYS_NICE)); | |
3965 | } | |
3966 | ||
3967 | #ifdef __ARCH_WANT_SYS_NICE | |
3968 | ||
3969 | /* | |
3970 | * sys_nice - change the priority of the current process. | |
3971 | * @increment: priority increment | |
3972 | * | |
3973 | * sys_setpriority is a more generic, but much slower function that | |
3974 | * does similar things. | |
3975 | */ | |
3976 | SYSCALL_DEFINE1(nice, int, increment) | |
3977 | { | |
3978 | long nice, retval; | |
3979 | ||
3980 | /* | |
3981 | * Setpriority might change our priority at the same moment. | |
3982 | * We don't have to worry. Conceptually one call occurs first | |
3983 | * and we have a single winner. | |
3984 | */ | |
3985 | increment = clamp(increment, -NICE_WIDTH, NICE_WIDTH); | |
3986 | nice = task_nice(current) + increment; | |
3987 | ||
3988 | nice = clamp_val(nice, MIN_NICE, MAX_NICE); | |
3989 | if (increment < 0 && !can_nice(current, nice)) | |
3990 | return -EPERM; | |
3991 | ||
3992 | retval = security_task_setnice(current, nice); | |
3993 | if (retval) | |
3994 | return retval; | |
3995 | ||
3996 | set_user_nice(current, nice); | |
3997 | return 0; | |
3998 | } | |
3999 | ||
4000 | #endif | |
4001 | ||
4002 | /** | |
4003 | * task_prio - return the priority value of a given task. | |
4004 | * @p: the task in question. | |
4005 | * | |
4006 | * Return: The priority value as seen by users in /proc. | |
4007 | * RT tasks are offset by -200. Normal tasks are centered | |
4008 | * around 0, value goes from -16 to +15. | |
4009 | */ | |
4010 | int task_prio(const struct task_struct *p) | |
4011 | { | |
4012 | return p->prio - MAX_RT_PRIO; | |
4013 | } | |
4014 | ||
4015 | /** | |
4016 | * idle_cpu - is a given CPU idle currently? | |
4017 | * @cpu: the processor in question. | |
4018 | * | |
4019 | * Return: 1 if the CPU is currently idle. 0 otherwise. | |
4020 | */ | |
4021 | int idle_cpu(int cpu) | |
4022 | { | |
4023 | struct rq *rq = cpu_rq(cpu); | |
4024 | ||
4025 | if (rq->curr != rq->idle) | |
4026 | return 0; | |
4027 | ||
4028 | if (rq->nr_running) | |
4029 | return 0; | |
4030 | ||
4031 | #ifdef CONFIG_SMP | |
4032 | if (!llist_empty(&rq->wake_list)) | |
4033 | return 0; | |
4034 | #endif | |
4035 | ||
4036 | return 1; | |
4037 | } | |
4038 | ||
4039 | /** | |
4040 | * idle_task - return the idle task for a given CPU. | |
4041 | * @cpu: the processor in question. | |
4042 | * | |
4043 | * Return: The idle task for the CPU @cpu. | |
4044 | */ | |
4045 | struct task_struct *idle_task(int cpu) | |
4046 | { | |
4047 | return cpu_rq(cpu)->idle; | |
4048 | } | |
4049 | ||
4050 | /** | |
4051 | * find_process_by_pid - find a process with a matching PID value. | |
4052 | * @pid: the pid in question. | |
4053 | * | |
4054 | * The task of @pid, if found. %NULL otherwise. | |
4055 | */ | |
4056 | static struct task_struct *find_process_by_pid(pid_t pid) | |
4057 | { | |
4058 | return pid ? find_task_by_vpid(pid) : current; | |
4059 | } | |
4060 | ||
4061 | /* | |
4062 | * sched_setparam() passes in -1 for its policy, to let the functions | |
4063 | * it calls know not to change it. | |
4064 | */ | |
4065 | #define SETPARAM_POLICY -1 | |
4066 | ||
4067 | static void __setscheduler_params(struct task_struct *p, | |
4068 | const struct sched_attr *attr) | |
4069 | { | |
4070 | int policy = attr->sched_policy; | |
4071 | ||
4072 | if (policy == SETPARAM_POLICY) | |
4073 | policy = p->policy; | |
4074 | ||
4075 | p->policy = policy; | |
4076 | ||
4077 | if (dl_policy(policy)) | |
4078 | __setparam_dl(p, attr); | |
4079 | else if (fair_policy(policy)) | |
4080 | p->static_prio = NICE_TO_PRIO(attr->sched_nice); | |
4081 | ||
4082 | /* | |
4083 | * __sched_setscheduler() ensures attr->sched_priority == 0 when | |
4084 | * !rt_policy. Always setting this ensures that things like | |
4085 | * getparam()/getattr() don't report silly values for !rt tasks. | |
4086 | */ | |
4087 | p->rt_priority = attr->sched_priority; | |
4088 | p->normal_prio = normal_prio(p); | |
4089 | set_load_weight(p, true); | |
4090 | } | |
4091 | ||
4092 | /* Actually do priority change: must hold pi & rq lock. */ | |
4093 | static void __setscheduler(struct rq *rq, struct task_struct *p, | |
4094 | const struct sched_attr *attr, bool keep_boost) | |
4095 | { | |
4096 | __setscheduler_params(p, attr); | |
4097 | ||
4098 | /* | |
4099 | * Keep a potential priority boosting if called from | |
4100 | * sched_setscheduler(). | |
4101 | */ | |
4102 | p->prio = normal_prio(p); | |
4103 | if (keep_boost) | |
4104 | p->prio = rt_effective_prio(p, p->prio); | |
4105 | ||
4106 | if (dl_prio(p->prio)) | |
4107 | p->sched_class = &dl_sched_class; | |
4108 | else if (rt_prio(p->prio)) | |
4109 | p->sched_class = &rt_sched_class; | |
4110 | else | |
4111 | p->sched_class = &fair_sched_class; | |
4112 | } | |
4113 | ||
4114 | /* | |
4115 | * Check the target process has a UID that matches the current process's: | |
4116 | */ | |
4117 | static bool check_same_owner(struct task_struct *p) | |
4118 | { | |
4119 | const struct cred *cred = current_cred(), *pcred; | |
4120 | bool match; | |
4121 | ||
4122 | rcu_read_lock(); | |
4123 | pcred = __task_cred(p); | |
4124 | match = (uid_eq(cred->euid, pcred->euid) || | |
4125 | uid_eq(cred->euid, pcred->uid)); | |
4126 | rcu_read_unlock(); | |
4127 | return match; | |
4128 | } | |
4129 | ||
4130 | static int __sched_setscheduler(struct task_struct *p, | |
4131 | const struct sched_attr *attr, | |
4132 | bool user, bool pi) | |
4133 | { | |
4134 | int newprio = dl_policy(attr->sched_policy) ? MAX_DL_PRIO - 1 : | |
4135 | MAX_RT_PRIO - 1 - attr->sched_priority; | |
4136 | int retval, oldprio, oldpolicy = -1, queued, running; | |
4137 | int new_effective_prio, policy = attr->sched_policy; | |
4138 | const struct sched_class *prev_class; | |
4139 | struct rq_flags rf; | |
4140 | int reset_on_fork; | |
4141 | int queue_flags = DEQUEUE_SAVE | DEQUEUE_MOVE | DEQUEUE_NOCLOCK; | |
4142 | struct rq *rq; | |
4143 | ||
4144 | /* The pi code expects interrupts enabled */ | |
4145 | BUG_ON(pi && in_interrupt()); | |
4146 | recheck: | |
4147 | /* Double check policy once rq lock held: */ | |
4148 | if (policy < 0) { | |
4149 | reset_on_fork = p->sched_reset_on_fork; | |
4150 | policy = oldpolicy = p->policy; | |
4151 | } else { | |
4152 | reset_on_fork = !!(attr->sched_flags & SCHED_FLAG_RESET_ON_FORK); | |
4153 | ||
4154 | if (!valid_policy(policy)) | |
4155 | return -EINVAL; | |
4156 | } | |
4157 | ||
4158 | if (attr->sched_flags & ~(SCHED_FLAG_ALL | SCHED_FLAG_SUGOV)) | |
4159 | return -EINVAL; | |
4160 | ||
4161 | /* | |
4162 | * Valid priorities for SCHED_FIFO and SCHED_RR are | |
4163 | * 1..MAX_USER_RT_PRIO-1, valid priority for SCHED_NORMAL, | |
4164 | * SCHED_BATCH and SCHED_IDLE is 0. | |
4165 | */ | |
4166 | if ((p->mm && attr->sched_priority > MAX_USER_RT_PRIO-1) || | |
4167 | (!p->mm && attr->sched_priority > MAX_RT_PRIO-1)) | |
4168 | return -EINVAL; | |
4169 | if ((dl_policy(policy) && !__checkparam_dl(attr)) || | |
4170 | (rt_policy(policy) != (attr->sched_priority != 0))) | |
4171 | return -EINVAL; | |
4172 | ||
4173 | /* | |
4174 | * Allow unprivileged RT tasks to decrease priority: | |
4175 | */ | |
4176 | if (user && !capable(CAP_SYS_NICE)) { | |
4177 | if (fair_policy(policy)) { | |
4178 | if (attr->sched_nice < task_nice(p) && | |
4179 | !can_nice(p, attr->sched_nice)) | |
4180 | return -EPERM; | |
4181 | } | |
4182 | ||
4183 | if (rt_policy(policy)) { | |
4184 | unsigned long rlim_rtprio = | |
4185 | task_rlimit(p, RLIMIT_RTPRIO); | |
4186 | ||
4187 | /* Can't set/change the rt policy: */ | |
4188 | if (policy != p->policy && !rlim_rtprio) | |
4189 | return -EPERM; | |
4190 | ||
4191 | /* Can't increase priority: */ | |
4192 | if (attr->sched_priority > p->rt_priority && | |
4193 | attr->sched_priority > rlim_rtprio) | |
4194 | return -EPERM; | |
4195 | } | |
4196 | ||
4197 | /* | |
4198 | * Can't set/change SCHED_DEADLINE policy at all for now | |
4199 | * (safest behavior); in the future we would like to allow | |
4200 | * unprivileged DL tasks to increase their relative deadline | |
4201 | * or reduce their runtime (both ways reducing utilization) | |
4202 | */ | |
4203 | if (dl_policy(policy)) | |
4204 | return -EPERM; | |
4205 | ||
4206 | /* | |
4207 | * Treat SCHED_IDLE as nice 20. Only allow a switch to | |
4208 | * SCHED_NORMAL if the RLIMIT_NICE would normally permit it. | |
4209 | */ | |
4210 | if (idle_policy(p->policy) && !idle_policy(policy)) { | |
4211 | if (!can_nice(p, task_nice(p))) | |
4212 | return -EPERM; | |
4213 | } | |
4214 | ||
4215 | /* Can't change other user's priorities: */ | |
4216 | if (!check_same_owner(p)) | |
4217 | return -EPERM; | |
4218 | ||
4219 | /* Normal users shall not reset the sched_reset_on_fork flag: */ | |
4220 | if (p->sched_reset_on_fork && !reset_on_fork) | |
4221 | return -EPERM; | |
4222 | } | |
4223 | ||
4224 | if (user) { | |
4225 | if (attr->sched_flags & SCHED_FLAG_SUGOV) | |
4226 | return -EINVAL; | |
4227 | ||
4228 | retval = security_task_setscheduler(p); | |
4229 | if (retval) | |
4230 | return retval; | |
4231 | } | |
4232 | ||
4233 | /* | |
4234 | * Make sure no PI-waiters arrive (or leave) while we are | |
4235 | * changing the priority of the task: | |
4236 | * | |
4237 | * To be able to change p->policy safely, the appropriate | |
4238 | * runqueue lock must be held. | |
4239 | */ | |
4240 | rq = task_rq_lock(p, &rf); | |
4241 | update_rq_clock(rq); | |
4242 | ||
4243 | /* | |
4244 | * Changing the policy of the stop threads its a very bad idea: | |
4245 | */ | |
4246 | if (p == rq->stop) { | |
4247 | task_rq_unlock(rq, p, &rf); | |
4248 | return -EINVAL; | |
4249 | } | |
4250 | ||
4251 | /* | |
4252 | * If not changing anything there's no need to proceed further, | |
4253 | * but store a possible modification of reset_on_fork. | |
4254 | */ | |
4255 | if (unlikely(policy == p->policy)) { | |
4256 | if (fair_policy(policy) && attr->sched_nice != task_nice(p)) | |
4257 | goto change; | |
4258 | if (rt_policy(policy) && attr->sched_priority != p->rt_priority) | |
4259 | goto change; | |
4260 | if (dl_policy(policy) && dl_param_changed(p, attr)) | |
4261 | goto change; | |
4262 | ||
4263 | p->sched_reset_on_fork = reset_on_fork; | |
4264 | task_rq_unlock(rq, p, &rf); | |
4265 | return 0; | |
4266 | } | |
4267 | change: | |
4268 | ||
4269 | if (user) { | |
4270 | #ifdef CONFIG_RT_GROUP_SCHED | |
4271 | /* | |
4272 | * Do not allow realtime tasks into groups that have no runtime | |
4273 | * assigned. | |
4274 | */ | |
4275 | if (rt_bandwidth_enabled() && rt_policy(policy) && | |
4276 | task_group(p)->rt_bandwidth.rt_runtime == 0 && | |
4277 | !task_group_is_autogroup(task_group(p))) { | |
4278 | task_rq_unlock(rq, p, &rf); | |
4279 | return -EPERM; | |
4280 | } | |
4281 | #endif | |
4282 | #ifdef CONFIG_SMP | |
4283 | if (dl_bandwidth_enabled() && dl_policy(policy) && | |
4284 | !(attr->sched_flags & SCHED_FLAG_SUGOV)) { | |
4285 | cpumask_t *span = rq->rd->span; | |
4286 | ||
4287 | /* | |
4288 | * Don't allow tasks with an affinity mask smaller than | |
4289 | * the entire root_domain to become SCHED_DEADLINE. We | |
4290 | * will also fail if there's no bandwidth available. | |
4291 | */ | |
4292 | if (!cpumask_subset(span, &p->cpus_allowed) || | |
4293 | rq->rd->dl_bw.bw == 0) { | |
4294 | task_rq_unlock(rq, p, &rf); | |
4295 | return -EPERM; | |
4296 | } | |
4297 | } | |
4298 | #endif | |
4299 | } | |
4300 | ||
4301 | /* Re-check policy now with rq lock held: */ | |
4302 | if (unlikely(oldpolicy != -1 && oldpolicy != p->policy)) { | |
4303 | policy = oldpolicy = -1; | |
4304 | task_rq_unlock(rq, p, &rf); | |
4305 | goto recheck; | |
4306 | } | |
4307 | ||
4308 | /* | |
4309 | * If setscheduling to SCHED_DEADLINE (or changing the parameters | |
4310 | * of a SCHED_DEADLINE task) we need to check if enough bandwidth | |
4311 | * is available. | |
4312 | */ | |
4313 | if ((dl_policy(policy) || dl_task(p)) && sched_dl_overflow(p, policy, attr)) { | |
4314 | task_rq_unlock(rq, p, &rf); | |
4315 | return -EBUSY; | |
4316 | } | |
4317 | ||
4318 | p->sched_reset_on_fork = reset_on_fork; | |
4319 | oldprio = p->prio; | |
4320 | ||
4321 | if (pi) { | |
4322 | /* | |
4323 | * Take priority boosted tasks into account. If the new | |
4324 | * effective priority is unchanged, we just store the new | |
4325 | * normal parameters and do not touch the scheduler class and | |
4326 | * the runqueue. This will be done when the task deboost | |
4327 | * itself. | |
4328 | */ | |
4329 | new_effective_prio = rt_effective_prio(p, newprio); | |
4330 | if (new_effective_prio == oldprio) | |
4331 | queue_flags &= ~DEQUEUE_MOVE; | |
4332 | } | |
4333 | ||
4334 | queued = task_on_rq_queued(p); | |
4335 | running = task_current(rq, p); | |
4336 | if (queued) | |
4337 | dequeue_task(rq, p, queue_flags); | |
4338 | if (running) | |
4339 | put_prev_task(rq, p); | |
4340 | ||
4341 | prev_class = p->sched_class; | |
4342 | __setscheduler(rq, p, attr, pi); | |
4343 | ||
4344 | if (queued) { | |
4345 | /* | |
4346 | * We enqueue to tail when the priority of a task is | |
4347 | * increased (user space view). | |
4348 | */ | |
4349 | if (oldprio < p->prio) | |
4350 | queue_flags |= ENQUEUE_HEAD; | |
4351 | ||
4352 | enqueue_task(rq, p, queue_flags); | |
4353 | } | |
4354 | if (running) | |
4355 | set_curr_task(rq, p); | |
4356 | ||
4357 | check_class_changed(rq, p, prev_class, oldprio); | |
4358 | ||
4359 | /* Avoid rq from going away on us: */ | |
4360 | preempt_disable(); | |
4361 | task_rq_unlock(rq, p, &rf); | |
4362 | ||
4363 | if (pi) | |
4364 | rt_mutex_adjust_pi(p); | |
4365 | ||
4366 | /* Run balance callbacks after we've adjusted the PI chain: */ | |
4367 | balance_callback(rq); | |
4368 | preempt_enable(); | |
4369 | ||
4370 | return 0; | |
4371 | } | |
4372 | ||
4373 | static int _sched_setscheduler(struct task_struct *p, int policy, | |
4374 | const struct sched_param *param, bool check) | |
4375 | { | |
4376 | struct sched_attr attr = { | |
4377 | .sched_policy = policy, | |
4378 | .sched_priority = param->sched_priority, | |
4379 | .sched_nice = PRIO_TO_NICE(p->static_prio), | |
4380 | }; | |
4381 | ||
4382 | /* Fixup the legacy SCHED_RESET_ON_FORK hack. */ | |
4383 | if ((policy != SETPARAM_POLICY) && (policy & SCHED_RESET_ON_FORK)) { | |
4384 | attr.sched_flags |= SCHED_FLAG_RESET_ON_FORK; | |
4385 | policy &= ~SCHED_RESET_ON_FORK; | |
4386 | attr.sched_policy = policy; | |
4387 | } | |
4388 | ||
4389 | return __sched_setscheduler(p, &attr, check, true); | |
4390 | } | |
4391 | /** | |
4392 | * sched_setscheduler - change the scheduling policy and/or RT priority of a thread. | |
4393 | * @p: the task in question. | |
4394 | * @policy: new policy. | |
4395 | * @param: structure containing the new RT priority. | |
4396 | * | |
4397 | * Return: 0 on success. An error code otherwise. | |
4398 | * | |
4399 | * NOTE that the task may be already dead. | |
4400 | */ | |
4401 | int sched_setscheduler(struct task_struct *p, int policy, | |
4402 | const struct sched_param *param) | |
4403 | { | |
4404 | return _sched_setscheduler(p, policy, param, true); | |
4405 | } | |
4406 | EXPORT_SYMBOL_GPL(sched_setscheduler); | |
4407 | ||
4408 | int sched_setattr(struct task_struct *p, const struct sched_attr *attr) | |
4409 | { | |
4410 | return __sched_setscheduler(p, attr, true, true); | |
4411 | } | |
4412 | EXPORT_SYMBOL_GPL(sched_setattr); | |
4413 | ||
4414 | int sched_setattr_nocheck(struct task_struct *p, const struct sched_attr *attr) | |
4415 | { | |
4416 | return __sched_setscheduler(p, attr, false, true); | |
4417 | } | |
4418 | ||
4419 | /** | |
4420 | * sched_setscheduler_nocheck - change the scheduling policy and/or RT priority of a thread from kernelspace. | |
4421 | * @p: the task in question. | |
4422 | * @policy: new policy. | |
4423 | * @param: structure containing the new RT priority. | |
4424 | * | |
4425 | * Just like sched_setscheduler, only don't bother checking if the | |
4426 | * current context has permission. For example, this is needed in | |
4427 | * stop_machine(): we create temporary high priority worker threads, | |
4428 | * but our caller might not have that capability. | |
4429 | * | |
4430 | * Return: 0 on success. An error code otherwise. | |
4431 | */ | |
4432 | int sched_setscheduler_nocheck(struct task_struct *p, int policy, | |
4433 | const struct sched_param *param) | |
4434 | { | |
4435 | return _sched_setscheduler(p, policy, param, false); | |
4436 | } | |
4437 | EXPORT_SYMBOL_GPL(sched_setscheduler_nocheck); | |
4438 | ||
4439 | static int | |
4440 | do_sched_setscheduler(pid_t pid, int policy, struct sched_param __user *param) | |
4441 | { | |
4442 | struct sched_param lparam; | |
4443 | struct task_struct *p; | |
4444 | int retval; | |
4445 | ||
4446 | if (!param || pid < 0) | |
4447 | return -EINVAL; | |
4448 | if (copy_from_user(&lparam, param, sizeof(struct sched_param))) | |
4449 | return -EFAULT; | |
4450 | ||
4451 | rcu_read_lock(); | |
4452 | retval = -ESRCH; | |
4453 | p = find_process_by_pid(pid); | |
4454 | if (p != NULL) | |
4455 | retval = sched_setscheduler(p, policy, &lparam); | |
4456 | rcu_read_unlock(); | |
4457 | ||
4458 | return retval; | |
4459 | } | |
4460 | ||
4461 | /* | |
4462 | * Mimics kernel/events/core.c perf_copy_attr(). | |
4463 | */ | |
4464 | static int sched_copy_attr(struct sched_attr __user *uattr, struct sched_attr *attr) | |
4465 | { | |
4466 | u32 size; | |
4467 | int ret; | |
4468 | ||
4469 | if (!access_ok(VERIFY_WRITE, uattr, SCHED_ATTR_SIZE_VER0)) | |
4470 | return -EFAULT; | |
4471 | ||
4472 | /* Zero the full structure, so that a short copy will be nice: */ | |
4473 | memset(attr, 0, sizeof(*attr)); | |
4474 | ||
4475 | ret = get_user(size, &uattr->size); | |
4476 | if (ret) | |
4477 | return ret; | |
4478 | ||
4479 | /* Bail out on silly large: */ | |
4480 | if (size > PAGE_SIZE) | |
4481 | goto err_size; | |
4482 | ||
4483 | /* ABI compatibility quirk: */ | |
4484 | if (!size) | |
4485 | size = SCHED_ATTR_SIZE_VER0; | |
4486 | ||
4487 | if (size < SCHED_ATTR_SIZE_VER0) | |
4488 | goto err_size; | |
4489 | ||
4490 | /* | |
4491 | * If we're handed a bigger struct than we know of, | |
4492 | * ensure all the unknown bits are 0 - i.e. new | |
4493 | * user-space does not rely on any kernel feature | |
4494 | * extensions we dont know about yet. | |
4495 | */ | |
4496 | if (size > sizeof(*attr)) { | |
4497 | unsigned char __user *addr; | |
4498 | unsigned char __user *end; | |
4499 | unsigned char val; | |
4500 | ||
4501 | addr = (void __user *)uattr + sizeof(*attr); | |
4502 | end = (void __user *)uattr + size; | |
4503 | ||
4504 | for (; addr < end; addr++) { | |
4505 | ret = get_user(val, addr); | |
4506 | if (ret) | |
4507 | return ret; | |
4508 | if (val) | |
4509 | goto err_size; | |
4510 | } | |
4511 | size = sizeof(*attr); | |
4512 | } | |
4513 | ||
4514 | ret = copy_from_user(attr, uattr, size); | |
4515 | if (ret) | |
4516 | return -EFAULT; | |
4517 | ||
4518 | /* | |
4519 | * XXX: Do we want to be lenient like existing syscalls; or do we want | |
4520 | * to be strict and return an error on out-of-bounds values? | |
4521 | */ | |
4522 | attr->sched_nice = clamp(attr->sched_nice, MIN_NICE, MAX_NICE); | |
4523 | ||
4524 | return 0; | |
4525 | ||
4526 | err_size: | |
4527 | put_user(sizeof(*attr), &uattr->size); | |
4528 | return -E2BIG; | |
4529 | } | |
4530 | ||
4531 | /** | |
4532 | * sys_sched_setscheduler - set/change the scheduler policy and RT priority | |
4533 | * @pid: the pid in question. | |
4534 | * @policy: new policy. | |
4535 | * @param: structure containing the new RT priority. | |
4536 | * | |
4537 | * Return: 0 on success. An error code otherwise. | |
4538 | */ | |
4539 | SYSCALL_DEFINE3(sched_setscheduler, pid_t, pid, int, policy, struct sched_param __user *, param) | |
4540 | { | |
4541 | if (policy < 0) | |
4542 | return -EINVAL; | |
4543 | ||
4544 | return do_sched_setscheduler(pid, policy, param); | |
4545 | } | |
4546 | ||
4547 | /** | |
4548 | * sys_sched_setparam - set/change the RT priority of a thread | |
4549 | * @pid: the pid in question. | |
4550 | * @param: structure containing the new RT priority. | |
4551 | * | |
4552 | * Return: 0 on success. An error code otherwise. | |
4553 | */ | |
4554 | SYSCALL_DEFINE2(sched_setparam, pid_t, pid, struct sched_param __user *, param) | |
4555 | { | |
4556 | return do_sched_setscheduler(pid, SETPARAM_POLICY, param); | |
4557 | } | |
4558 | ||
4559 | /** | |
4560 | * sys_sched_setattr - same as above, but with extended sched_attr | |
4561 | * @pid: the pid in question. | |
4562 | * @uattr: structure containing the extended parameters. | |
4563 | * @flags: for future extension. | |
4564 | */ | |
4565 | SYSCALL_DEFINE3(sched_setattr, pid_t, pid, struct sched_attr __user *, uattr, | |
4566 | unsigned int, flags) | |
4567 | { | |
4568 | struct sched_attr attr; | |
4569 | struct task_struct *p; | |
4570 | int retval; | |
4571 | ||
4572 | if (!uattr || pid < 0 || flags) | |
4573 | return -EINVAL; | |
4574 | ||
4575 | retval = sched_copy_attr(uattr, &attr); | |
4576 | if (retval) | |
4577 | return retval; | |
4578 | ||
4579 | if ((int)attr.sched_policy < 0) | |
4580 | return -EINVAL; | |
4581 | ||
4582 | rcu_read_lock(); | |
4583 | retval = -ESRCH; | |
4584 | p = find_process_by_pid(pid); | |
4585 | if (p != NULL) | |
4586 | retval = sched_setattr(p, &attr); | |
4587 | rcu_read_unlock(); | |
4588 | ||
4589 | return retval; | |
4590 | } | |
4591 | ||
4592 | /** | |
4593 | * sys_sched_getscheduler - get the policy (scheduling class) of a thread | |
4594 | * @pid: the pid in question. | |
4595 | * | |
4596 | * Return: On success, the policy of the thread. Otherwise, a negative error | |
4597 | * code. | |
4598 | */ | |
4599 | SYSCALL_DEFINE1(sched_getscheduler, pid_t, pid) | |
4600 | { | |
4601 | struct task_struct *p; | |
4602 | int retval; | |
4603 | ||
4604 | if (pid < 0) | |
4605 | return -EINVAL; | |
4606 | ||
4607 | retval = -ESRCH; | |
4608 | rcu_read_lock(); | |
4609 | p = find_process_by_pid(pid); | |
4610 | if (p) { | |
4611 | retval = security_task_getscheduler(p); | |
4612 | if (!retval) | |
4613 | retval = p->policy | |
4614 | | (p->sched_reset_on_fork ? SCHED_RESET_ON_FORK : 0); | |
4615 | } | |
4616 | rcu_read_unlock(); | |
4617 | return retval; | |
4618 | } | |
4619 | ||
4620 | /** | |
4621 | * sys_sched_getparam - get the RT priority of a thread | |
4622 | * @pid: the pid in question. | |
4623 | * @param: structure containing the RT priority. | |
4624 | * | |
4625 | * Return: On success, 0 and the RT priority is in @param. Otherwise, an error | |
4626 | * code. | |
4627 | */ | |
4628 | SYSCALL_DEFINE2(sched_getparam, pid_t, pid, struct sched_param __user *, param) | |
4629 | { | |
4630 | struct sched_param lp = { .sched_priority = 0 }; | |
4631 | struct task_struct *p; | |
4632 | int retval; | |
4633 | ||
4634 | if (!param || pid < 0) | |
4635 | return -EINVAL; | |
4636 | ||
4637 | rcu_read_lock(); | |
4638 | p = find_process_by_pid(pid); | |
4639 | retval = -ESRCH; | |
4640 | if (!p) | |
4641 | goto out_unlock; | |
4642 | ||
4643 | retval = security_task_getscheduler(p); | |
4644 | if (retval) | |
4645 | goto out_unlock; | |
4646 | ||
4647 | if (task_has_rt_policy(p)) | |
4648 | lp.sched_priority = p->rt_priority; | |
4649 | rcu_read_unlock(); | |
4650 | ||
4651 | /* | |
4652 | * This one might sleep, we cannot do it with a spinlock held ... | |
4653 | */ | |
4654 | retval = copy_to_user(param, &lp, sizeof(*param)) ? -EFAULT : 0; | |
4655 | ||
4656 | return retval; | |
4657 | ||
4658 | out_unlock: | |
4659 | rcu_read_unlock(); | |
4660 | return retval; | |
4661 | } | |
4662 | ||
4663 | static int sched_read_attr(struct sched_attr __user *uattr, | |
4664 | struct sched_attr *attr, | |
4665 | unsigned int usize) | |
4666 | { | |
4667 | int ret; | |
4668 | ||
4669 | if (!access_ok(VERIFY_WRITE, uattr, usize)) | |
4670 | return -EFAULT; | |
4671 | ||
4672 | /* | |
4673 | * If we're handed a smaller struct than we know of, | |
4674 | * ensure all the unknown bits are 0 - i.e. old | |
4675 | * user-space does not get uncomplete information. | |
4676 | */ | |
4677 | if (usize < sizeof(*attr)) { | |
4678 | unsigned char *addr; | |
4679 | unsigned char *end; | |
4680 | ||
4681 | addr = (void *)attr + usize; | |
4682 | end = (void *)attr + sizeof(*attr); | |
4683 | ||
4684 | for (; addr < end; addr++) { | |
4685 | if (*addr) | |
4686 | return -EFBIG; | |
4687 | } | |
4688 | ||
4689 | attr->size = usize; | |
4690 | } | |
4691 | ||
4692 | ret = copy_to_user(uattr, attr, attr->size); | |
4693 | if (ret) | |
4694 | return -EFAULT; | |
4695 | ||
4696 | return 0; | |
4697 | } | |
4698 | ||
4699 | /** | |
4700 | * sys_sched_getattr - similar to sched_getparam, but with sched_attr | |
4701 | * @pid: the pid in question. | |
4702 | * @uattr: structure containing the extended parameters. | |
4703 | * @size: sizeof(attr) for fwd/bwd comp. | |
4704 | * @flags: for future extension. | |
4705 | */ | |
4706 | SYSCALL_DEFINE4(sched_getattr, pid_t, pid, struct sched_attr __user *, uattr, | |
4707 | unsigned int, size, unsigned int, flags) | |
4708 | { | |
4709 | struct sched_attr attr = { | |
4710 | .size = sizeof(struct sched_attr), | |
4711 | }; | |
4712 | struct task_struct *p; | |
4713 | int retval; | |
4714 | ||
4715 | if (!uattr || pid < 0 || size > PAGE_SIZE || | |
4716 | size < SCHED_ATTR_SIZE_VER0 || flags) | |
4717 | return -EINVAL; | |
4718 | ||
4719 | rcu_read_lock(); | |
4720 | p = find_process_by_pid(pid); | |
4721 | retval = -ESRCH; | |
4722 | if (!p) | |
4723 | goto out_unlock; | |
4724 | ||
4725 | retval = security_task_getscheduler(p); | |
4726 | if (retval) | |
4727 | goto out_unlock; | |
4728 | ||
4729 | attr.sched_policy = p->policy; | |
4730 | if (p->sched_reset_on_fork) | |
4731 | attr.sched_flags |= SCHED_FLAG_RESET_ON_FORK; | |
4732 | if (task_has_dl_policy(p)) | |
4733 | __getparam_dl(p, &attr); | |
4734 | else if (task_has_rt_policy(p)) | |
4735 | attr.sched_priority = p->rt_priority; | |
4736 | else | |
4737 | attr.sched_nice = task_nice(p); | |
4738 | ||
4739 | rcu_read_unlock(); | |
4740 | ||
4741 | retval = sched_read_attr(uattr, &attr, size); | |
4742 | return retval; | |
4743 | ||
4744 | out_unlock: | |
4745 | rcu_read_unlock(); | |
4746 | return retval; | |
4747 | } | |
4748 | ||
4749 | long sched_setaffinity(pid_t pid, const struct cpumask *in_mask) | |
4750 | { | |
4751 | cpumask_var_t cpus_allowed, new_mask; | |
4752 | struct task_struct *p; | |
4753 | int retval; | |
4754 | ||
4755 | rcu_read_lock(); | |
4756 | ||
4757 | p = find_process_by_pid(pid); | |
4758 | if (!p) { | |
4759 | rcu_read_unlock(); | |
4760 | return -ESRCH; | |
4761 | } | |
4762 | ||
4763 | /* Prevent p going away */ | |
4764 | get_task_struct(p); | |
4765 | rcu_read_unlock(); | |
4766 | ||
4767 | if (p->flags & PF_NO_SETAFFINITY) { | |
4768 | retval = -EINVAL; | |
4769 | goto out_put_task; | |
4770 | } | |
4771 | if (!alloc_cpumask_var(&cpus_allowed, GFP_KERNEL)) { | |
4772 | retval = -ENOMEM; | |
4773 | goto out_put_task; | |
4774 | } | |
4775 | if (!alloc_cpumask_var(&new_mask, GFP_KERNEL)) { | |
4776 | retval = -ENOMEM; | |
4777 | goto out_free_cpus_allowed; | |
4778 | } | |
4779 | retval = -EPERM; | |
4780 | if (!check_same_owner(p)) { | |
4781 | rcu_read_lock(); | |
4782 | if (!ns_capable(__task_cred(p)->user_ns, CAP_SYS_NICE)) { | |
4783 | rcu_read_unlock(); | |
4784 | goto out_free_new_mask; | |
4785 | } | |
4786 | rcu_read_unlock(); | |
4787 | } | |
4788 | ||
4789 | retval = security_task_setscheduler(p); | |
4790 | if (retval) | |
4791 | goto out_free_new_mask; | |
4792 | ||
4793 | ||
4794 | cpuset_cpus_allowed(p, cpus_allowed); | |
4795 | cpumask_and(new_mask, in_mask, cpus_allowed); | |
4796 | ||
4797 | /* | |
4798 | * Since bandwidth control happens on root_domain basis, | |
4799 | * if admission test is enabled, we only admit -deadline | |
4800 | * tasks allowed to run on all the CPUs in the task's | |
4801 | * root_domain. | |
4802 | */ | |
4803 | #ifdef CONFIG_SMP | |
4804 | if (task_has_dl_policy(p) && dl_bandwidth_enabled()) { | |
4805 | rcu_read_lock(); | |
4806 | if (!cpumask_subset(task_rq(p)->rd->span, new_mask)) { | |
4807 | retval = -EBUSY; | |
4808 | rcu_read_unlock(); | |
4809 | goto out_free_new_mask; | |
4810 | } | |
4811 | rcu_read_unlock(); | |
4812 | } | |
4813 | #endif | |
4814 | again: | |
4815 | retval = __set_cpus_allowed_ptr(p, new_mask, true); | |
4816 | ||
4817 | if (!retval) { | |
4818 | cpuset_cpus_allowed(p, cpus_allowed); | |
4819 | if (!cpumask_subset(new_mask, cpus_allowed)) { | |
4820 | /* | |
4821 | * We must have raced with a concurrent cpuset | |
4822 | * update. Just reset the cpus_allowed to the | |
4823 | * cpuset's cpus_allowed | |
4824 | */ | |
4825 | cpumask_copy(new_mask, cpus_allowed); | |
4826 | goto again; | |
4827 | } | |
4828 | } | |
4829 | out_free_new_mask: | |
4830 | free_cpumask_var(new_mask); | |
4831 | out_free_cpus_allowed: | |
4832 | free_cpumask_var(cpus_allowed); | |
4833 | out_put_task: | |
4834 | put_task_struct(p); | |
4835 | return retval; | |
4836 | } | |
4837 | ||
4838 | static int get_user_cpu_mask(unsigned long __user *user_mask_ptr, unsigned len, | |
4839 | struct cpumask *new_mask) | |
4840 | { | |
4841 | if (len < cpumask_size()) | |
4842 | cpumask_clear(new_mask); | |
4843 | else if (len > cpumask_size()) | |
4844 | len = cpumask_size(); | |
4845 | ||
4846 | return copy_from_user(new_mask, user_mask_ptr, len) ? -EFAULT : 0; | |
4847 | } | |
4848 | ||
4849 | /** | |
4850 | * sys_sched_setaffinity - set the CPU affinity of a process | |
4851 | * @pid: pid of the process | |
4852 | * @len: length in bytes of the bitmask pointed to by user_mask_ptr | |
4853 | * @user_mask_ptr: user-space pointer to the new CPU mask | |
4854 | * | |
4855 | * Return: 0 on success. An error code otherwise. | |
4856 | */ | |
4857 | SYSCALL_DEFINE3(sched_setaffinity, pid_t, pid, unsigned int, len, | |
4858 | unsigned long __user *, user_mask_ptr) | |
4859 | { | |
4860 | cpumask_var_t new_mask; | |
4861 | int retval; | |
4862 | ||
4863 | if (!alloc_cpumask_var(&new_mask, GFP_KERNEL)) | |
4864 | return -ENOMEM; | |
4865 | ||
4866 | retval = get_user_cpu_mask(user_mask_ptr, len, new_mask); | |
4867 | if (retval == 0) | |
4868 | retval = sched_setaffinity(pid, new_mask); | |
4869 | free_cpumask_var(new_mask); | |
4870 | return retval; | |
4871 | } | |
4872 | ||
4873 | long sched_getaffinity(pid_t pid, struct cpumask *mask) | |
4874 | { | |
4875 | struct task_struct *p; | |
4876 | unsigned long flags; | |
4877 | int retval; | |
4878 | ||
4879 | rcu_read_lock(); | |
4880 | ||
4881 | retval = -ESRCH; | |
4882 | p = find_process_by_pid(pid); | |
4883 | if (!p) | |
4884 | goto out_unlock; | |
4885 | ||
4886 | retval = security_task_getscheduler(p); | |
4887 | if (retval) | |
4888 | goto out_unlock; | |
4889 | ||
4890 | raw_spin_lock_irqsave(&p->pi_lock, flags); | |
4891 | cpumask_and(mask, &p->cpus_allowed, cpu_active_mask); | |
4892 | raw_spin_unlock_irqrestore(&p->pi_lock, flags); | |
4893 | ||
4894 | out_unlock: | |
4895 | rcu_read_unlock(); | |
4896 | ||
4897 | return retval; | |
4898 | } | |
4899 | ||
4900 | /** | |
4901 | * sys_sched_getaffinity - get the CPU affinity of a process | |
4902 | * @pid: pid of the process | |
4903 | * @len: length in bytes of the bitmask pointed to by user_mask_ptr | |
4904 | * @user_mask_ptr: user-space pointer to hold the current CPU mask | |
4905 | * | |
4906 | * Return: size of CPU mask copied to user_mask_ptr on success. An | |
4907 | * error code otherwise. | |
4908 | */ | |
4909 | SYSCALL_DEFINE3(sched_getaffinity, pid_t, pid, unsigned int, len, | |
4910 | unsigned long __user *, user_mask_ptr) | |
4911 | { | |
4912 | int ret; | |
4913 | cpumask_var_t mask; | |
4914 | ||
4915 | if ((len * BITS_PER_BYTE) < nr_cpu_ids) | |
4916 | return -EINVAL; | |
4917 | if (len & (sizeof(unsigned long)-1)) | |
4918 | return -EINVAL; | |
4919 | ||
4920 | if (!alloc_cpumask_var(&mask, GFP_KERNEL)) | |
4921 | return -ENOMEM; | |
4922 | ||
4923 | ret = sched_getaffinity(pid, mask); | |
4924 | if (ret == 0) { | |
4925 | unsigned int retlen = min(len, cpumask_size()); | |
4926 | ||
4927 | if (copy_to_user(user_mask_ptr, mask, retlen)) | |
4928 | ret = -EFAULT; | |
4929 | else | |
4930 | ret = retlen; | |
4931 | } | |
4932 | free_cpumask_var(mask); | |
4933 | ||
4934 | return ret; | |
4935 | } | |
4936 | ||
4937 | /** | |
4938 | * sys_sched_yield - yield the current processor to other threads. | |
4939 | * | |
4940 | * This function yields the current CPU to other tasks. If there are no | |
4941 | * other threads running on this CPU then this function will return. | |
4942 | * | |
4943 | * Return: 0. | |
4944 | */ | |
4945 | SYSCALL_DEFINE0(sched_yield) | |
4946 | { | |
4947 | struct rq_flags rf; | |
4948 | struct rq *rq; | |
4949 | ||
4950 | local_irq_disable(); | |
4951 | rq = this_rq(); | |
4952 | rq_lock(rq, &rf); | |
4953 | ||
4954 | schedstat_inc(rq->yld_count); | |
4955 | current->sched_class->yield_task(rq); | |
4956 | ||
4957 | /* | |
4958 | * Since we are going to call schedule() anyway, there's | |
4959 | * no need to preempt or enable interrupts: | |
4960 | */ | |
4961 | preempt_disable(); | |
4962 | rq_unlock(rq, &rf); | |
4963 | sched_preempt_enable_no_resched(); | |
4964 | ||
4965 | schedule(); | |
4966 | ||
4967 | return 0; | |
4968 | } | |
4969 | ||
4970 | #ifndef CONFIG_PREEMPT | |
4971 | int __sched _cond_resched(void) | |
4972 | { | |
4973 | if (should_resched(0)) { | |
4974 | preempt_schedule_common(); | |
4975 | return 1; | |
4976 | } | |
4977 | rcu_all_qs(); | |
4978 | return 0; | |
4979 | } | |
4980 | EXPORT_SYMBOL(_cond_resched); | |
4981 | #endif | |
4982 | ||
4983 | /* | |
4984 | * __cond_resched_lock() - if a reschedule is pending, drop the given lock, | |
4985 | * call schedule, and on return reacquire the lock. | |
4986 | * | |
4987 | * This works OK both with and without CONFIG_PREEMPT. We do strange low-level | |
4988 | * operations here to prevent schedule() from being called twice (once via | |
4989 | * spin_unlock(), once by hand). | |
4990 | */ | |
4991 | int __cond_resched_lock(spinlock_t *lock) | |
4992 | { | |
4993 | int resched = should_resched(PREEMPT_LOCK_OFFSET); | |
4994 | int ret = 0; | |
4995 | ||
4996 | lockdep_assert_held(lock); | |
4997 | ||
4998 | if (spin_needbreak(lock) || resched) { | |
4999 | spin_unlock(lock); | |
5000 | if (resched) | |
5001 | preempt_schedule_common(); | |
5002 | else | |
5003 | cpu_relax(); | |
5004 | ret = 1; | |
5005 | spin_lock(lock); | |
5006 | } | |
5007 | return ret; | |
5008 | } | |
5009 | EXPORT_SYMBOL(__cond_resched_lock); | |
5010 | ||
5011 | int __sched __cond_resched_softirq(void) | |
5012 | { | |
5013 | BUG_ON(!in_softirq()); | |
5014 | ||
5015 | if (should_resched(SOFTIRQ_DISABLE_OFFSET)) { | |
5016 | local_bh_enable(); | |
5017 | preempt_schedule_common(); | |
5018 | local_bh_disable(); | |
5019 | return 1; | |
5020 | } | |
5021 | return 0; | |
5022 | } | |
5023 | EXPORT_SYMBOL(__cond_resched_softirq); | |
5024 | ||
5025 | /** | |
5026 | * yield - yield the current processor to other threads. | |
5027 | * | |
5028 | * Do not ever use this function, there's a 99% chance you're doing it wrong. | |
5029 | * | |
5030 | * The scheduler is at all times free to pick the calling task as the most | |
5031 | * eligible task to run, if removing the yield() call from your code breaks | |
5032 | * it, its already broken. | |
5033 | * | |
5034 | * Typical broken usage is: | |
5035 | * | |
5036 | * while (!event) | |
5037 | * yield(); | |
5038 | * | |
5039 | * where one assumes that yield() will let 'the other' process run that will | |
5040 | * make event true. If the current task is a SCHED_FIFO task that will never | |
5041 | * happen. Never use yield() as a progress guarantee!! | |
5042 | * | |
5043 | * If you want to use yield() to wait for something, use wait_event(). | |
5044 | * If you want to use yield() to be 'nice' for others, use cond_resched(). | |
5045 | * If you still want to use yield(), do not! | |
5046 | */ | |
5047 | void __sched yield(void) | |
5048 | { | |
5049 | set_current_state(TASK_RUNNING); | |
5050 | sys_sched_yield(); | |
5051 | } | |
5052 | EXPORT_SYMBOL(yield); | |
5053 | ||
5054 | /** | |
5055 | * yield_to - yield the current processor to another thread in | |
5056 | * your thread group, or accelerate that thread toward the | |
5057 | * processor it's on. | |
5058 | * @p: target task | |
5059 | * @preempt: whether task preemption is allowed or not | |
5060 | * | |
5061 | * It's the caller's job to ensure that the target task struct | |
5062 | * can't go away on us before we can do any checks. | |
5063 | * | |
5064 | * Return: | |
5065 | * true (>0) if we indeed boosted the target task. | |
5066 | * false (0) if we failed to boost the target. | |
5067 | * -ESRCH if there's no task to yield to. | |
5068 | */ | |
5069 | int __sched yield_to(struct task_struct *p, bool preempt) | |
5070 | { | |
5071 | struct task_struct *curr = current; | |
5072 | struct rq *rq, *p_rq; | |
5073 | unsigned long flags; | |
5074 | int yielded = 0; | |
5075 | ||
5076 | local_irq_save(flags); | |
5077 | rq = this_rq(); | |
5078 | ||
5079 | again: | |
5080 | p_rq = task_rq(p); | |
5081 | /* | |
5082 | * If we're the only runnable task on the rq and target rq also | |
5083 | * has only one task, there's absolutely no point in yielding. | |
5084 | */ | |
5085 | if (rq->nr_running == 1 && p_rq->nr_running == 1) { | |
5086 | yielded = -ESRCH; | |
5087 | goto out_irq; | |
5088 | } | |
5089 | ||
5090 | double_rq_lock(rq, p_rq); | |
5091 | if (task_rq(p) != p_rq) { | |
5092 | double_rq_unlock(rq, p_rq); | |
5093 | goto again; | |
5094 | } | |
5095 | ||
5096 | if (!curr->sched_class->yield_to_task) | |
5097 | goto out_unlock; | |
5098 | ||
5099 | if (curr->sched_class != p->sched_class) | |
5100 | goto out_unlock; | |
5101 | ||
5102 | if (task_running(p_rq, p) || p->state) | |
5103 | goto out_unlock; | |
5104 | ||
5105 | yielded = curr->sched_class->yield_to_task(rq, p, preempt); | |
5106 | if (yielded) { | |
5107 | schedstat_inc(rq->yld_count); | |
5108 | /* | |
5109 | * Make p's CPU reschedule; pick_next_entity takes care of | |
5110 | * fairness. | |
5111 | */ | |
5112 | if (preempt && rq != p_rq) | |
5113 | resched_curr(p_rq); | |
5114 | } | |
5115 | ||
5116 | out_unlock: | |
5117 | double_rq_unlock(rq, p_rq); | |
5118 | out_irq: | |
5119 | local_irq_restore(flags); | |
5120 | ||
5121 | if (yielded > 0) | |
5122 | schedule(); | |
5123 | ||
5124 | return yielded; | |
5125 | } | |
5126 | EXPORT_SYMBOL_GPL(yield_to); | |
5127 | ||
5128 | int io_schedule_prepare(void) | |
5129 | { | |
5130 | int old_iowait = current->in_iowait; | |
5131 | ||
5132 | current->in_iowait = 1; | |
5133 | blk_schedule_flush_plug(current); | |
5134 | ||
5135 | return old_iowait; | |
5136 | } | |
5137 | ||
5138 | void io_schedule_finish(int token) | |
5139 | { | |
5140 | current->in_iowait = token; | |
5141 | } | |
5142 | ||
5143 | /* | |
5144 | * This task is about to go to sleep on IO. Increment rq->nr_iowait so | |
5145 | * that process accounting knows that this is a task in IO wait state. | |
5146 | */ | |
5147 | long __sched io_schedule_timeout(long timeout) | |
5148 | { | |
5149 | int token; | |
5150 | long ret; | |
5151 | ||
5152 | token = io_schedule_prepare(); | |
5153 | ret = schedule_timeout(timeout); | |
5154 | io_schedule_finish(token); | |
5155 | ||
5156 | return ret; | |
5157 | } | |
5158 | EXPORT_SYMBOL(io_schedule_timeout); | |
5159 | ||
5160 | void io_schedule(void) | |
5161 | { | |
5162 | int token; | |
5163 | ||
5164 | token = io_schedule_prepare(); | |
5165 | schedule(); | |
5166 | io_schedule_finish(token); | |
5167 | } | |
5168 | EXPORT_SYMBOL(io_schedule); | |
5169 | ||
5170 | /** | |
5171 | * sys_sched_get_priority_max - return maximum RT priority. | |
5172 | * @policy: scheduling class. | |
5173 | * | |
5174 | * Return: On success, this syscall returns the maximum | |
5175 | * rt_priority that can be used by a given scheduling class. | |
5176 | * On failure, a negative error code is returned. | |
5177 | */ | |
5178 | SYSCALL_DEFINE1(sched_get_priority_max, int, policy) | |
5179 | { | |
5180 | int ret = -EINVAL; | |
5181 | ||
5182 | switch (policy) { | |
5183 | case SCHED_FIFO: | |
5184 | case SCHED_RR: | |
5185 | ret = MAX_USER_RT_PRIO-1; | |
5186 | break; | |
5187 | case SCHED_DEADLINE: | |
5188 | case SCHED_NORMAL: | |
5189 | case SCHED_BATCH: | |
5190 | case SCHED_IDLE: | |
5191 | ret = 0; | |
5192 | break; | |
5193 | } | |
5194 | return ret; | |
5195 | } | |
5196 | ||
5197 | /** | |
5198 | * sys_sched_get_priority_min - return minimum RT priority. | |
5199 | * @policy: scheduling class. | |
5200 | * | |
5201 | * Return: On success, this syscall returns the minimum | |
5202 | * rt_priority that can be used by a given scheduling class. | |
5203 | * On failure, a negative error code is returned. | |
5204 | */ | |
5205 | SYSCALL_DEFINE1(sched_get_priority_min, int, policy) | |
5206 | { | |
5207 | int ret = -EINVAL; | |
5208 | ||
5209 | switch (policy) { | |
5210 | case SCHED_FIFO: | |
5211 | case SCHED_RR: | |
5212 | ret = 1; | |
5213 | break; | |
5214 | case SCHED_DEADLINE: | |
5215 | case SCHED_NORMAL: | |
5216 | case SCHED_BATCH: | |
5217 | case SCHED_IDLE: | |
5218 | ret = 0; | |
5219 | } | |
5220 | return ret; | |
5221 | } | |
5222 | ||
5223 | static int sched_rr_get_interval(pid_t pid, struct timespec64 *t) | |
5224 | { | |
5225 | struct task_struct *p; | |
5226 | unsigned int time_slice; | |
5227 | struct rq_flags rf; | |
5228 | struct rq *rq; | |
5229 | int retval; | |
5230 | ||
5231 | if (pid < 0) | |
5232 | return -EINVAL; | |
5233 | ||
5234 | retval = -ESRCH; | |
5235 | rcu_read_lock(); | |
5236 | p = find_process_by_pid(pid); | |
5237 | if (!p) | |
5238 | goto out_unlock; | |
5239 | ||
5240 | retval = security_task_getscheduler(p); | |
5241 | if (retval) | |
5242 | goto out_unlock; | |
5243 | ||
5244 | rq = task_rq_lock(p, &rf); | |
5245 | time_slice = 0; | |
5246 | if (p->sched_class->get_rr_interval) | |
5247 | time_slice = p->sched_class->get_rr_interval(rq, p); | |
5248 | task_rq_unlock(rq, p, &rf); | |
5249 | ||
5250 | rcu_read_unlock(); | |
5251 | jiffies_to_timespec64(time_slice, t); | |
5252 | return 0; | |
5253 | ||
5254 | out_unlock: | |
5255 | rcu_read_unlock(); | |
5256 | return retval; | |
5257 | } | |
5258 | ||
5259 | /** | |
5260 | * sys_sched_rr_get_interval - return the default timeslice of a process. | |
5261 | * @pid: pid of the process. | |
5262 | * @interval: userspace pointer to the timeslice value. | |
5263 | * | |
5264 | * this syscall writes the default timeslice value of a given process | |
5265 | * into the user-space timespec buffer. A value of '0' means infinity. | |
5266 | * | |
5267 | * Return: On success, 0 and the timeslice is in @interval. Otherwise, | |
5268 | * an error code. | |
5269 | */ | |
5270 | SYSCALL_DEFINE2(sched_rr_get_interval, pid_t, pid, | |
5271 | struct timespec __user *, interval) | |
5272 | { | |
5273 | struct timespec64 t; | |
5274 | int retval = sched_rr_get_interval(pid, &t); | |
5275 | ||
5276 | if (retval == 0) | |
5277 | retval = put_timespec64(&t, interval); | |
5278 | ||
5279 | return retval; | |
5280 | } | |
5281 | ||
5282 | #ifdef CONFIG_COMPAT | |
5283 | COMPAT_SYSCALL_DEFINE2(sched_rr_get_interval, | |
5284 | compat_pid_t, pid, | |
5285 | struct compat_timespec __user *, interval) | |
5286 | { | |
5287 | struct timespec64 t; | |
5288 | int retval = sched_rr_get_interval(pid, &t); | |
5289 | ||
5290 | if (retval == 0) | |
5291 | retval = compat_put_timespec64(&t, interval); | |
5292 | return retval; | |
5293 | } | |
5294 | #endif | |
5295 | ||
5296 | void sched_show_task(struct task_struct *p) | |
5297 | { | |
5298 | unsigned long free = 0; | |
5299 | int ppid; | |
5300 | ||
5301 | if (!try_get_task_stack(p)) | |
5302 | return; | |
5303 | ||
5304 | printk(KERN_INFO "%-15.15s %c", p->comm, task_state_to_char(p)); | |
5305 | ||
5306 | if (p->state == TASK_RUNNING) | |
5307 | printk(KERN_CONT " running task "); | |
5308 | #ifdef CONFIG_DEBUG_STACK_USAGE | |
5309 | free = stack_not_used(p); | |
5310 | #endif | |
5311 | ppid = 0; | |
5312 | rcu_read_lock(); | |
5313 | if (pid_alive(p)) | |
5314 | ppid = task_pid_nr(rcu_dereference(p->real_parent)); | |
5315 | rcu_read_unlock(); | |
5316 | printk(KERN_CONT "%5lu %5d %6d 0x%08lx\n", free, | |
5317 | task_pid_nr(p), ppid, | |
5318 | (unsigned long)task_thread_info(p)->flags); | |
5319 | ||
5320 | print_worker_info(KERN_INFO, p); | |
5321 | show_stack(p, NULL); | |
5322 | put_task_stack(p); | |
5323 | } | |
5324 | EXPORT_SYMBOL_GPL(sched_show_task); | |
5325 | ||
5326 | static inline bool | |
5327 | state_filter_match(unsigned long state_filter, struct task_struct *p) | |
5328 | { | |
5329 | /* no filter, everything matches */ | |
5330 | if (!state_filter) | |
5331 | return true; | |
5332 | ||
5333 | /* filter, but doesn't match */ | |
5334 | if (!(p->state & state_filter)) | |
5335 | return false; | |
5336 | ||
5337 | /* | |
5338 | * When looking for TASK_UNINTERRUPTIBLE skip TASK_IDLE (allows | |
5339 | * TASK_KILLABLE). | |
5340 | */ | |
5341 | if (state_filter == TASK_UNINTERRUPTIBLE && p->state == TASK_IDLE) | |
5342 | return false; | |
5343 | ||
5344 | return true; | |
5345 | } | |
5346 | ||
5347 | ||
5348 | void show_state_filter(unsigned long state_filter) | |
5349 | { | |
5350 | struct task_struct *g, *p; | |
5351 | ||
5352 | #if BITS_PER_LONG == 32 | |
5353 | printk(KERN_INFO | |
5354 | " task PC stack pid father\n"); | |
5355 | #else | |
5356 | printk(KERN_INFO | |
5357 | " task PC stack pid father\n"); | |
5358 | #endif | |
5359 | rcu_read_lock(); | |
5360 | for_each_process_thread(g, p) { | |
5361 | /* | |
5362 | * reset the NMI-timeout, listing all files on a slow | |
5363 | * console might take a lot of time: | |
5364 | * Also, reset softlockup watchdogs on all CPUs, because | |
5365 | * another CPU might be blocked waiting for us to process | |
5366 | * an IPI. | |
5367 | */ | |
5368 | touch_nmi_watchdog(); | |
5369 | touch_all_softlockup_watchdogs(); | |
5370 | if (state_filter_match(state_filter, p)) | |
5371 | sched_show_task(p); | |
5372 | } | |
5373 | ||
5374 | #ifdef CONFIG_SCHED_DEBUG | |
5375 | if (!state_filter) | |
5376 | sysrq_sched_debug_show(); | |
5377 | #endif | |
5378 | rcu_read_unlock(); | |
5379 | /* | |
5380 | * Only show locks if all tasks are dumped: | |
5381 | */ | |
5382 | if (!state_filter) | |
5383 | debug_show_all_locks(); | |
5384 | } | |
5385 | ||
5386 | /** | |
5387 | * init_idle - set up an idle thread for a given CPU | |
5388 | * @idle: task in question | |
5389 | * @cpu: CPU the idle task belongs to | |
5390 | * | |
5391 | * NOTE: this function does not set the idle thread's NEED_RESCHED | |
5392 | * flag, to make booting more robust. | |
5393 | */ | |
5394 | void init_idle(struct task_struct *idle, int cpu) | |
5395 | { | |
5396 | struct rq *rq = cpu_rq(cpu); | |
5397 | unsigned long flags; | |
5398 | ||
5399 | raw_spin_lock_irqsave(&idle->pi_lock, flags); | |
5400 | raw_spin_lock(&rq->lock); | |
5401 | ||
5402 | __sched_fork(0, idle); | |
5403 | idle->state = TASK_RUNNING; | |
5404 | idle->se.exec_start = sched_clock(); | |
5405 | idle->flags |= PF_IDLE; | |
5406 | ||
5407 | kasan_unpoison_task_stack(idle); | |
5408 | ||
5409 | #ifdef CONFIG_SMP | |
5410 | /* | |
5411 | * Its possible that init_idle() gets called multiple times on a task, | |
5412 | * in that case do_set_cpus_allowed() will not do the right thing. | |
5413 | * | |
5414 | * And since this is boot we can forgo the serialization. | |
5415 | */ | |
5416 | set_cpus_allowed_common(idle, cpumask_of(cpu)); | |
5417 | #endif | |
5418 | /* | |
5419 | * We're having a chicken and egg problem, even though we are | |
5420 | * holding rq->lock, the CPU isn't yet set to this CPU so the | |
5421 | * lockdep check in task_group() will fail. | |
5422 | * | |
5423 | * Similar case to sched_fork(). / Alternatively we could | |
5424 | * use task_rq_lock() here and obtain the other rq->lock. | |
5425 | * | |
5426 | * Silence PROVE_RCU | |
5427 | */ | |
5428 | rcu_read_lock(); | |
5429 | __set_task_cpu(idle, cpu); | |
5430 | rcu_read_unlock(); | |
5431 | ||
5432 | rq->curr = rq->idle = idle; | |
5433 | idle->on_rq = TASK_ON_RQ_QUEUED; | |
5434 | #ifdef CONFIG_SMP | |
5435 | idle->on_cpu = 1; | |
5436 | #endif | |
5437 | raw_spin_unlock(&rq->lock); | |
5438 | raw_spin_unlock_irqrestore(&idle->pi_lock, flags); | |
5439 | ||
5440 | /* Set the preempt count _outside_ the spinlocks! */ | |
5441 | init_idle_preempt_count(idle, cpu); | |
5442 | ||
5443 | /* | |
5444 | * The idle tasks have their own, simple scheduling class: | |
5445 | */ | |
5446 | idle->sched_class = &idle_sched_class; | |
5447 | ftrace_graph_init_idle_task(idle, cpu); | |
5448 | vtime_init_idle(idle, cpu); | |
5449 | #ifdef CONFIG_SMP | |
5450 | sprintf(idle->comm, "%s/%d", INIT_TASK_COMM, cpu); | |
5451 | #endif | |
5452 | } | |
5453 | ||
5454 | #ifdef CONFIG_SMP | |
5455 | ||
5456 | int cpuset_cpumask_can_shrink(const struct cpumask *cur, | |
5457 | const struct cpumask *trial) | |
5458 | { | |
5459 | int ret = 1; | |
5460 | ||
5461 | if (!cpumask_weight(cur)) | |
5462 | return ret; | |
5463 | ||
5464 | ret = dl_cpuset_cpumask_can_shrink(cur, trial); | |
5465 | ||
5466 | return ret; | |
5467 | } | |
5468 | ||
5469 | int task_can_attach(struct task_struct *p, | |
5470 | const struct cpumask *cs_cpus_allowed) | |
5471 | { | |
5472 | int ret = 0; | |
5473 | ||
5474 | /* | |
5475 | * Kthreads which disallow setaffinity shouldn't be moved | |
5476 | * to a new cpuset; we don't want to change their CPU | |
5477 | * affinity and isolating such threads by their set of | |
5478 | * allowed nodes is unnecessary. Thus, cpusets are not | |
5479 | * applicable for such threads. This prevents checking for | |
5480 | * success of set_cpus_allowed_ptr() on all attached tasks | |
5481 | * before cpus_allowed may be changed. | |
5482 | */ | |
5483 | if (p->flags & PF_NO_SETAFFINITY) { | |
5484 | ret = -EINVAL; | |
5485 | goto out; | |
5486 | } | |
5487 | ||
5488 | if (dl_task(p) && !cpumask_intersects(task_rq(p)->rd->span, | |
5489 | cs_cpus_allowed)) | |
5490 | ret = dl_task_can_attach(p, cs_cpus_allowed); | |
5491 | ||
5492 | out: | |
5493 | return ret; | |
5494 | } | |
5495 | ||
5496 | bool sched_smp_initialized __read_mostly; | |
5497 | ||
5498 | #ifdef CONFIG_NUMA_BALANCING | |
5499 | /* Migrate current task p to target_cpu */ | |
5500 | int migrate_task_to(struct task_struct *p, int target_cpu) | |
5501 | { | |
5502 | struct migration_arg arg = { p, target_cpu }; | |
5503 | int curr_cpu = task_cpu(p); | |
5504 | ||
5505 | if (curr_cpu == target_cpu) | |
5506 | return 0; | |
5507 | ||
5508 | if (!cpumask_test_cpu(target_cpu, &p->cpus_allowed)) | |
5509 | return -EINVAL; | |
5510 | ||
5511 | /* TODO: This is not properly updating schedstats */ | |
5512 | ||
5513 | trace_sched_move_numa(p, curr_cpu, target_cpu); | |
5514 | return stop_one_cpu(curr_cpu, migration_cpu_stop, &arg); | |
5515 | } | |
5516 | ||
5517 | /* | |
5518 | * Requeue a task on a given node and accurately track the number of NUMA | |
5519 | * tasks on the runqueues | |
5520 | */ | |
5521 | void sched_setnuma(struct task_struct *p, int nid) | |
5522 | { | |
5523 | bool queued, running; | |
5524 | struct rq_flags rf; | |
5525 | struct rq *rq; | |
5526 | ||
5527 | rq = task_rq_lock(p, &rf); | |
5528 | queued = task_on_rq_queued(p); | |
5529 | running = task_current(rq, p); | |
5530 | ||
5531 | if (queued) | |
5532 | dequeue_task(rq, p, DEQUEUE_SAVE); | |
5533 | if (running) | |
5534 | put_prev_task(rq, p); | |
5535 | ||
5536 | p->numa_preferred_nid = nid; | |
5537 | ||
5538 | if (queued) | |
5539 | enqueue_task(rq, p, ENQUEUE_RESTORE | ENQUEUE_NOCLOCK); | |
5540 | if (running) | |
5541 | set_curr_task(rq, p); | |
5542 | task_rq_unlock(rq, p, &rf); | |
5543 | } | |
5544 | #endif /* CONFIG_NUMA_BALANCING */ | |
5545 | ||
5546 | #ifdef CONFIG_HOTPLUG_CPU | |
5547 | /* | |
5548 | * Ensure that the idle task is using init_mm right before its CPU goes | |
5549 | * offline. | |
5550 | */ | |
5551 | void idle_task_exit(void) | |
5552 | { | |
5553 | struct mm_struct *mm = current->active_mm; | |
5554 | ||
5555 | BUG_ON(cpu_online(smp_processor_id())); | |
5556 | ||
5557 | if (mm != &init_mm) { | |
5558 | switch_mm(mm, &init_mm, current); | |
5559 | finish_arch_post_lock_switch(); | |
5560 | } | |
5561 | mmdrop(mm); | |
5562 | } | |
5563 | ||
5564 | /* | |
5565 | * Since this CPU is going 'away' for a while, fold any nr_active delta | |
5566 | * we might have. Assumes we're called after migrate_tasks() so that the | |
5567 | * nr_active count is stable. We need to take the teardown thread which | |
5568 | * is calling this into account, so we hand in adjust = 1 to the load | |
5569 | * calculation. | |
5570 | * | |
5571 | * Also see the comment "Global load-average calculations". | |
5572 | */ | |
5573 | static void calc_load_migrate(struct rq *rq) | |
5574 | { | |
5575 | long delta = calc_load_fold_active(rq, 1); | |
5576 | if (delta) | |
5577 | atomic_long_add(delta, &calc_load_tasks); | |
5578 | } | |
5579 | ||
5580 | static void put_prev_task_fake(struct rq *rq, struct task_struct *prev) | |
5581 | { | |
5582 | } | |
5583 | ||
5584 | static const struct sched_class fake_sched_class = { | |
5585 | .put_prev_task = put_prev_task_fake, | |
5586 | }; | |
5587 | ||
5588 | static struct task_struct fake_task = { | |
5589 | /* | |
5590 | * Avoid pull_{rt,dl}_task() | |
5591 | */ | |
5592 | .prio = MAX_PRIO + 1, | |
5593 | .sched_class = &fake_sched_class, | |
5594 | }; | |
5595 | ||
5596 | /* | |
5597 | * Migrate all tasks from the rq, sleeping tasks will be migrated by | |
5598 | * try_to_wake_up()->select_task_rq(). | |
5599 | * | |
5600 | * Called with rq->lock held even though we'er in stop_machine() and | |
5601 | * there's no concurrency possible, we hold the required locks anyway | |
5602 | * because of lock validation efforts. | |
5603 | */ | |
5604 | static void migrate_tasks(struct rq *dead_rq, struct rq_flags *rf) | |
5605 | { | |
5606 | struct rq *rq = dead_rq; | |
5607 | struct task_struct *next, *stop = rq->stop; | |
5608 | struct rq_flags orf = *rf; | |
5609 | int dest_cpu; | |
5610 | ||
5611 | /* | |
5612 | * Fudge the rq selection such that the below task selection loop | |
5613 | * doesn't get stuck on the currently eligible stop task. | |
5614 | * | |
5615 | * We're currently inside stop_machine() and the rq is either stuck | |
5616 | * in the stop_machine_cpu_stop() loop, or we're executing this code, | |
5617 | * either way we should never end up calling schedule() until we're | |
5618 | * done here. | |
5619 | */ | |
5620 | rq->stop = NULL; | |
5621 | ||
5622 | /* | |
5623 | * put_prev_task() and pick_next_task() sched | |
5624 | * class method both need to have an up-to-date | |
5625 | * value of rq->clock[_task] | |
5626 | */ | |
5627 | update_rq_clock(rq); | |
5628 | ||
5629 | for (;;) { | |
5630 | /* | |
5631 | * There's this thread running, bail when that's the only | |
5632 | * remaining thread: | |
5633 | */ | |
5634 | if (rq->nr_running == 1) | |
5635 | break; | |
5636 | ||
5637 | /* | |
5638 | * pick_next_task() assumes pinned rq->lock: | |
5639 | */ | |
5640 | next = pick_next_task(rq, &fake_task, rf); | |
5641 | BUG_ON(!next); | |
5642 | put_prev_task(rq, next); | |
5643 | ||
5644 | /* | |
5645 | * Rules for changing task_struct::cpus_allowed are holding | |
5646 | * both pi_lock and rq->lock, such that holding either | |
5647 | * stabilizes the mask. | |
5648 | * | |
5649 | * Drop rq->lock is not quite as disastrous as it usually is | |
5650 | * because !cpu_active at this point, which means load-balance | |
5651 | * will not interfere. Also, stop-machine. | |
5652 | */ | |
5653 | rq_unlock(rq, rf); | |
5654 | raw_spin_lock(&next->pi_lock); | |
5655 | rq_relock(rq, rf); | |
5656 | ||
5657 | /* | |
5658 | * Since we're inside stop-machine, _nothing_ should have | |
5659 | * changed the task, WARN if weird stuff happened, because in | |
5660 | * that case the above rq->lock drop is a fail too. | |
5661 | */ | |
5662 | if (WARN_ON(task_rq(next) != rq || !task_on_rq_queued(next))) { | |
5663 | raw_spin_unlock(&next->pi_lock); | |
5664 | continue; | |
5665 | } | |
5666 | ||
5667 | /* Find suitable destination for @next, with force if needed. */ | |
5668 | dest_cpu = select_fallback_rq(dead_rq->cpu, next); | |
5669 | rq = __migrate_task(rq, rf, next, dest_cpu); | |
5670 | if (rq != dead_rq) { | |
5671 | rq_unlock(rq, rf); | |
5672 | rq = dead_rq; | |
5673 | *rf = orf; | |
5674 | rq_relock(rq, rf); | |
5675 | } | |
5676 | raw_spin_unlock(&next->pi_lock); | |
5677 | } | |
5678 | ||
5679 | rq->stop = stop; | |
5680 | } | |
5681 | #endif /* CONFIG_HOTPLUG_CPU */ | |
5682 | ||
5683 | void set_rq_online(struct rq *rq) | |
5684 | { | |
5685 | if (!rq->online) { | |
5686 | const struct sched_class *class; | |
5687 | ||
5688 | cpumask_set_cpu(rq->cpu, rq->rd->online); | |
5689 | rq->online = 1; | |
5690 | ||
5691 | for_each_class(class) { | |
5692 | if (class->rq_online) | |
5693 | class->rq_online(rq); | |
5694 | } | |
5695 | } | |
5696 | } | |
5697 | ||
5698 | void set_rq_offline(struct rq *rq) | |
5699 | { | |
5700 | if (rq->online) { | |
5701 | const struct sched_class *class; | |
5702 | ||
5703 | for_each_class(class) { | |
5704 | if (class->rq_offline) | |
5705 | class->rq_offline(rq); | |
5706 | } | |
5707 | ||
5708 | cpumask_clear_cpu(rq->cpu, rq->rd->online); | |
5709 | rq->online = 0; | |
5710 | } | |
5711 | } | |
5712 | ||
5713 | static void set_cpu_rq_start_time(unsigned int cpu) | |
5714 | { | |
5715 | struct rq *rq = cpu_rq(cpu); | |
5716 | ||
5717 | rq->age_stamp = sched_clock_cpu(cpu); | |
5718 | } | |
5719 | ||
5720 | /* | |
5721 | * used to mark begin/end of suspend/resume: | |
5722 | */ | |
5723 | static int num_cpus_frozen; | |
5724 | ||
5725 | /* | |
5726 | * Update cpusets according to cpu_active mask. If cpusets are | |
5727 | * disabled, cpuset_update_active_cpus() becomes a simple wrapper | |
5728 | * around partition_sched_domains(). | |
5729 | * | |
5730 | * If we come here as part of a suspend/resume, don't touch cpusets because we | |
5731 | * want to restore it back to its original state upon resume anyway. | |
5732 | */ | |
5733 | static void cpuset_cpu_active(void) | |
5734 | { | |
5735 | if (cpuhp_tasks_frozen) { | |
5736 | /* | |
5737 | * num_cpus_frozen tracks how many CPUs are involved in suspend | |
5738 | * resume sequence. As long as this is not the last online | |
5739 | * operation in the resume sequence, just build a single sched | |
5740 | * domain, ignoring cpusets. | |
5741 | */ | |
5742 | partition_sched_domains(1, NULL, NULL); | |
5743 | if (--num_cpus_frozen) | |
5744 | return; | |
5745 | /* | |
5746 | * This is the last CPU online operation. So fall through and | |
5747 | * restore the original sched domains by considering the | |
5748 | * cpuset configurations. | |
5749 | */ | |
5750 | cpuset_force_rebuild(); | |
5751 | } | |
5752 | cpuset_update_active_cpus(); | |
5753 | } | |
5754 | ||
5755 | static int cpuset_cpu_inactive(unsigned int cpu) | |
5756 | { | |
5757 | if (!cpuhp_tasks_frozen) { | |
5758 | if (dl_cpu_busy(cpu)) | |
5759 | return -EBUSY; | |
5760 | cpuset_update_active_cpus(); | |
5761 | } else { | |
5762 | num_cpus_frozen++; | |
5763 | partition_sched_domains(1, NULL, NULL); | |
5764 | } | |
5765 | return 0; | |
5766 | } | |
5767 | ||
5768 | int sched_cpu_activate(unsigned int cpu) | |
5769 | { | |
5770 | struct rq *rq = cpu_rq(cpu); | |
5771 | struct rq_flags rf; | |
5772 | ||
5773 | set_cpu_active(cpu, true); | |
5774 | ||
5775 | if (sched_smp_initialized) { | |
5776 | sched_domains_numa_masks_set(cpu); | |
5777 | cpuset_cpu_active(); | |
5778 | } | |
5779 | ||
5780 | /* | |
5781 | * Put the rq online, if not already. This happens: | |
5782 | * | |
5783 | * 1) In the early boot process, because we build the real domains | |
5784 | * after all CPUs have been brought up. | |
5785 | * | |
5786 | * 2) At runtime, if cpuset_cpu_active() fails to rebuild the | |
5787 | * domains. | |
5788 | */ | |
5789 | rq_lock_irqsave(rq, &rf); | |
5790 | if (rq->rd) { | |
5791 | BUG_ON(!cpumask_test_cpu(cpu, rq->rd->span)); | |
5792 | set_rq_online(rq); | |
5793 | } | |
5794 | rq_unlock_irqrestore(rq, &rf); | |
5795 | ||
5796 | update_max_interval(); | |
5797 | ||
5798 | return 0; | |
5799 | } | |
5800 | ||
5801 | int sched_cpu_deactivate(unsigned int cpu) | |
5802 | { | |
5803 | int ret; | |
5804 | ||
5805 | set_cpu_active(cpu, false); | |
5806 | /* | |
5807 | * We've cleared cpu_active_mask, wait for all preempt-disabled and RCU | |
5808 | * users of this state to go away such that all new such users will | |
5809 | * observe it. | |
5810 | * | |
5811 | * Do sync before park smpboot threads to take care the rcu boost case. | |
5812 | */ | |
5813 | synchronize_rcu_mult(call_rcu, call_rcu_sched); | |
5814 | ||
5815 | if (!sched_smp_initialized) | |
5816 | return 0; | |
5817 | ||
5818 | ret = cpuset_cpu_inactive(cpu); | |
5819 | if (ret) { | |
5820 | set_cpu_active(cpu, true); | |
5821 | return ret; | |
5822 | } | |
5823 | sched_domains_numa_masks_clear(cpu); | |
5824 | return 0; | |
5825 | } | |
5826 | ||
5827 | static void sched_rq_cpu_starting(unsigned int cpu) | |
5828 | { | |
5829 | struct rq *rq = cpu_rq(cpu); | |
5830 | ||
5831 | rq->calc_load_update = calc_load_update; | |
5832 | update_max_interval(); | |
5833 | } | |
5834 | ||
5835 | int sched_cpu_starting(unsigned int cpu) | |
5836 | { | |
5837 | set_cpu_rq_start_time(cpu); | |
5838 | sched_rq_cpu_starting(cpu); | |
5839 | sched_tick_start(cpu); | |
5840 | return 0; | |
5841 | } | |
5842 | ||
5843 | #ifdef CONFIG_HOTPLUG_CPU | |
5844 | int sched_cpu_dying(unsigned int cpu) | |
5845 | { | |
5846 | struct rq *rq = cpu_rq(cpu); | |
5847 | struct rq_flags rf; | |
5848 | ||
5849 | /* Handle pending wakeups and then migrate everything off */ | |
5850 | sched_ttwu_pending(); | |
5851 | sched_tick_stop(cpu); | |
5852 | ||
5853 | rq_lock_irqsave(rq, &rf); | |
5854 | if (rq->rd) { | |
5855 | BUG_ON(!cpumask_test_cpu(cpu, rq->rd->span)); | |
5856 | set_rq_offline(rq); | |
5857 | } | |
5858 | migrate_tasks(rq, &rf); | |
5859 | BUG_ON(rq->nr_running != 1); | |
5860 | rq_unlock_irqrestore(rq, &rf); | |
5861 | ||
5862 | calc_load_migrate(rq); | |
5863 | update_max_interval(); | |
5864 | nohz_balance_exit_idle(cpu); | |
5865 | hrtick_clear(rq); | |
5866 | return 0; | |
5867 | } | |
5868 | #endif | |
5869 | ||
5870 | #ifdef CONFIG_SCHED_SMT | |
5871 | DEFINE_STATIC_KEY_FALSE(sched_smt_present); | |
5872 | ||
5873 | static void sched_init_smt(void) | |
5874 | { | |
5875 | /* | |
5876 | * We've enumerated all CPUs and will assume that if any CPU | |
5877 | * has SMT siblings, CPU0 will too. | |
5878 | */ | |
5879 | if (cpumask_weight(cpu_smt_mask(0)) > 1) | |
5880 | static_branch_enable(&sched_smt_present); | |
5881 | } | |
5882 | #else | |
5883 | static inline void sched_init_smt(void) { } | |
5884 | #endif | |
5885 | ||
5886 | void __init sched_init_smp(void) | |
5887 | { | |
5888 | sched_init_numa(); | |
5889 | ||
5890 | /* | |
5891 | * There's no userspace yet to cause hotplug operations; hence all the | |
5892 | * CPU masks are stable and all blatant races in the below code cannot | |
5893 | * happen. | |
5894 | */ | |
5895 | mutex_lock(&sched_domains_mutex); | |
5896 | sched_init_domains(cpu_active_mask); | |
5897 | mutex_unlock(&sched_domains_mutex); | |
5898 | ||
5899 | /* Move init over to a non-isolated CPU */ | |
5900 | if (set_cpus_allowed_ptr(current, housekeeping_cpumask(HK_FLAG_DOMAIN)) < 0) | |
5901 | BUG(); | |
5902 | sched_init_granularity(); | |
5903 | ||
5904 | init_sched_rt_class(); | |
5905 | init_sched_dl_class(); | |
5906 | ||
5907 | sched_init_smt(); | |
5908 | ||
5909 | sched_smp_initialized = true; | |
5910 | } | |
5911 | ||
5912 | static int __init migration_init(void) | |
5913 | { | |
5914 | sched_rq_cpu_starting(smp_processor_id()); | |
5915 | return 0; | |
5916 | } | |
5917 | early_initcall(migration_init); | |
5918 | ||
5919 | #else | |
5920 | void __init sched_init_smp(void) | |
5921 | { | |
5922 | sched_init_granularity(); | |
5923 | } | |
5924 | #endif /* CONFIG_SMP */ | |
5925 | ||
5926 | int in_sched_functions(unsigned long addr) | |
5927 | { | |
5928 | return in_lock_functions(addr) || | |
5929 | (addr >= (unsigned long)__sched_text_start | |
5930 | && addr < (unsigned long)__sched_text_end); | |
5931 | } | |
5932 | ||
5933 | #ifdef CONFIG_CGROUP_SCHED | |
5934 | /* | |
5935 | * Default task group. | |
5936 | * Every task in system belongs to this group at bootup. | |
5937 | */ | |
5938 | struct task_group root_task_group; | |
5939 | LIST_HEAD(task_groups); | |
5940 | ||
5941 | /* Cacheline aligned slab cache for task_group */ | |
5942 | static struct kmem_cache *task_group_cache __read_mostly; | |
5943 | #endif | |
5944 | ||
5945 | DECLARE_PER_CPU(cpumask_var_t, load_balance_mask); | |
5946 | DECLARE_PER_CPU(cpumask_var_t, select_idle_mask); | |
5947 | ||
5948 | void __init sched_init(void) | |
5949 | { | |
5950 | int i, j; | |
5951 | unsigned long alloc_size = 0, ptr; | |
5952 | ||
5953 | sched_clock_init(); | |
5954 | wait_bit_init(); | |
5955 | ||
5956 | #ifdef CONFIG_FAIR_GROUP_SCHED | |
5957 | alloc_size += 2 * nr_cpu_ids * sizeof(void **); | |
5958 | #endif | |
5959 | #ifdef CONFIG_RT_GROUP_SCHED | |
5960 | alloc_size += 2 * nr_cpu_ids * sizeof(void **); | |
5961 | #endif | |
5962 | if (alloc_size) { | |
5963 | ptr = (unsigned long)kzalloc(alloc_size, GFP_NOWAIT); | |
5964 | ||
5965 | #ifdef CONFIG_FAIR_GROUP_SCHED | |
5966 | root_task_group.se = (struct sched_entity **)ptr; | |
5967 | ptr += nr_cpu_ids * sizeof(void **); | |
5968 | ||
5969 | root_task_group.cfs_rq = (struct cfs_rq **)ptr; | |
5970 | ptr += nr_cpu_ids * sizeof(void **); | |
5971 | ||
5972 | #endif /* CONFIG_FAIR_GROUP_SCHED */ | |
5973 | #ifdef CONFIG_RT_GROUP_SCHED | |
5974 | root_task_group.rt_se = (struct sched_rt_entity **)ptr; | |
5975 | ptr += nr_cpu_ids * sizeof(void **); | |
5976 | ||
5977 | root_task_group.rt_rq = (struct rt_rq **)ptr; | |
5978 | ptr += nr_cpu_ids * sizeof(void **); | |
5979 | ||
5980 | #endif /* CONFIG_RT_GROUP_SCHED */ | |
5981 | } | |
5982 | #ifdef CONFIG_CPUMASK_OFFSTACK | |
5983 | for_each_possible_cpu(i) { | |
5984 | per_cpu(load_balance_mask, i) = (cpumask_var_t)kzalloc_node( | |
5985 | cpumask_size(), GFP_KERNEL, cpu_to_node(i)); | |
5986 | per_cpu(select_idle_mask, i) = (cpumask_var_t)kzalloc_node( | |
5987 | cpumask_size(), GFP_KERNEL, cpu_to_node(i)); | |
5988 | } | |
5989 | #endif /* CONFIG_CPUMASK_OFFSTACK */ | |
5990 | ||
5991 | init_rt_bandwidth(&def_rt_bandwidth, global_rt_period(), global_rt_runtime()); | |
5992 | init_dl_bandwidth(&def_dl_bandwidth, global_rt_period(), global_rt_runtime()); | |
5993 | ||
5994 | #ifdef CONFIG_SMP | |
5995 | init_defrootdomain(); | |
5996 | #endif | |
5997 | ||
5998 | #ifdef CONFIG_RT_GROUP_SCHED | |
5999 | init_rt_bandwidth(&root_task_group.rt_bandwidth, | |
6000 | global_rt_period(), global_rt_runtime()); | |
6001 | #endif /* CONFIG_RT_GROUP_SCHED */ | |
6002 | ||
6003 | #ifdef CONFIG_CGROUP_SCHED | |
6004 | task_group_cache = KMEM_CACHE(task_group, 0); | |
6005 | ||
6006 | list_add(&root_task_group.list, &task_groups); | |
6007 | INIT_LIST_HEAD(&root_task_group.children); | |
6008 | INIT_LIST_HEAD(&root_task_group.siblings); | |
6009 | autogroup_init(&init_task); | |
6010 | #endif /* CONFIG_CGROUP_SCHED */ | |
6011 | ||
6012 | for_each_possible_cpu(i) { | |
6013 | struct rq *rq; | |
6014 | ||
6015 | rq = cpu_rq(i); | |
6016 | raw_spin_lock_init(&rq->lock); | |
6017 | rq->nr_running = 0; | |
6018 | rq->calc_load_active = 0; | |
6019 | rq->calc_load_update = jiffies + LOAD_FREQ; | |
6020 | init_cfs_rq(&rq->cfs); | |
6021 | init_rt_rq(&rq->rt); | |
6022 | init_dl_rq(&rq->dl); | |
6023 | #ifdef CONFIG_FAIR_GROUP_SCHED | |
6024 | root_task_group.shares = ROOT_TASK_GROUP_LOAD; | |
6025 | INIT_LIST_HEAD(&rq->leaf_cfs_rq_list); | |
6026 | rq->tmp_alone_branch = &rq->leaf_cfs_rq_list; | |
6027 | /* | |
6028 | * How much CPU bandwidth does root_task_group get? | |
6029 | * | |
6030 | * In case of task-groups formed thr' the cgroup filesystem, it | |
6031 | * gets 100% of the CPU resources in the system. This overall | |
6032 | * system CPU resource is divided among the tasks of | |
6033 | * root_task_group and its child task-groups in a fair manner, | |
6034 | * based on each entity's (task or task-group's) weight | |
6035 | * (se->load.weight). | |
6036 | * | |
6037 | * In other words, if root_task_group has 10 tasks of weight | |
6038 | * 1024) and two child groups A0 and A1 (of weight 1024 each), | |
6039 | * then A0's share of the CPU resource is: | |
6040 | * | |
6041 | * A0's bandwidth = 1024 / (10*1024 + 1024 + 1024) = 8.33% | |
6042 | * | |
6043 | * We achieve this by letting root_task_group's tasks sit | |
6044 | * directly in rq->cfs (i.e root_task_group->se[] = NULL). | |
6045 | */ | |
6046 | init_cfs_bandwidth(&root_task_group.cfs_bandwidth); | |
6047 | init_tg_cfs_entry(&root_task_group, &rq->cfs, NULL, i, NULL); | |
6048 | #endif /* CONFIG_FAIR_GROUP_SCHED */ | |
6049 | ||
6050 | rq->rt.rt_runtime = def_rt_bandwidth.rt_runtime; | |
6051 | #ifdef CONFIG_RT_GROUP_SCHED | |
6052 | init_tg_rt_entry(&root_task_group, &rq->rt, NULL, i, NULL); | |
6053 | #endif | |
6054 | ||
6055 | for (j = 0; j < CPU_LOAD_IDX_MAX; j++) | |
6056 | rq->cpu_load[j] = 0; | |
6057 | ||
6058 | #ifdef CONFIG_SMP | |
6059 | rq->sd = NULL; | |
6060 | rq->rd = NULL; | |
6061 | rq->cpu_capacity = rq->cpu_capacity_orig = SCHED_CAPACITY_SCALE; | |
6062 | rq->balance_callback = NULL; | |
6063 | rq->active_balance = 0; | |
6064 | rq->next_balance = jiffies; | |
6065 | rq->push_cpu = 0; | |
6066 | rq->cpu = i; | |
6067 | rq->online = 0; | |
6068 | rq->idle_stamp = 0; | |
6069 | rq->avg_idle = 2*sysctl_sched_migration_cost; | |
6070 | rq->max_idle_balance_cost = sysctl_sched_migration_cost; | |
6071 | ||
6072 | INIT_LIST_HEAD(&rq->cfs_tasks); | |
6073 | ||
6074 | rq_attach_root(rq, &def_root_domain); | |
6075 | #ifdef CONFIG_NO_HZ_COMMON | |
6076 | rq->last_load_update_tick = jiffies; | |
6077 | atomic_set(&rq->nohz_flags, 0); | |
6078 | #endif | |
6079 | #endif /* CONFIG_SMP */ | |
6080 | hrtick_rq_init(rq); | |
6081 | atomic_set(&rq->nr_iowait, 0); | |
6082 | } | |
6083 | ||
6084 | set_load_weight(&init_task, false); | |
6085 | ||
6086 | /* | |
6087 | * The boot idle thread does lazy MMU switching as well: | |
6088 | */ | |
6089 | mmgrab(&init_mm); | |
6090 | enter_lazy_tlb(&init_mm, current); | |
6091 | ||
6092 | /* | |
6093 | * Make us the idle thread. Technically, schedule() should not be | |
6094 | * called from this thread, however somewhere below it might be, | |
6095 | * but because we are the idle thread, we just pick up running again | |
6096 | * when this runqueue becomes "idle". | |
6097 | */ | |
6098 | init_idle(current, smp_processor_id()); | |
6099 | ||
6100 | calc_load_update = jiffies + LOAD_FREQ; | |
6101 | ||
6102 | #ifdef CONFIG_SMP | |
6103 | idle_thread_set_boot_cpu(); | |
6104 | set_cpu_rq_start_time(smp_processor_id()); | |
6105 | #endif | |
6106 | init_sched_fair_class(); | |
6107 | ||
6108 | init_schedstats(); | |
6109 | ||
6110 | scheduler_running = 1; | |
6111 | } | |
6112 | ||
6113 | #ifdef CONFIG_DEBUG_ATOMIC_SLEEP | |
6114 | static inline int preempt_count_equals(int preempt_offset) | |
6115 | { | |
6116 | int nested = preempt_count() + rcu_preempt_depth(); | |
6117 | ||
6118 | return (nested == preempt_offset); | |
6119 | } | |
6120 | ||
6121 | void __might_sleep(const char *file, int line, int preempt_offset) | |
6122 | { | |
6123 | /* | |
6124 | * Blocking primitives will set (and therefore destroy) current->state, | |
6125 | * since we will exit with TASK_RUNNING make sure we enter with it, | |
6126 | * otherwise we will destroy state. | |
6127 | */ | |
6128 | WARN_ONCE(current->state != TASK_RUNNING && current->task_state_change, | |
6129 | "do not call blocking ops when !TASK_RUNNING; " | |
6130 | "state=%lx set at [<%p>] %pS\n", | |
6131 | current->state, | |
6132 | (void *)current->task_state_change, | |
6133 | (void *)current->task_state_change); | |
6134 | ||
6135 | ___might_sleep(file, line, preempt_offset); | |
6136 | } | |
6137 | EXPORT_SYMBOL(__might_sleep); | |
6138 | ||
6139 | void ___might_sleep(const char *file, int line, int preempt_offset) | |
6140 | { | |
6141 | /* Ratelimiting timestamp: */ | |
6142 | static unsigned long prev_jiffy; | |
6143 | ||
6144 | unsigned long preempt_disable_ip; | |
6145 | ||
6146 | /* WARN_ON_ONCE() by default, no rate limit required: */ | |
6147 | rcu_sleep_check(); | |
6148 | ||
6149 | if ((preempt_count_equals(preempt_offset) && !irqs_disabled() && | |
6150 | !is_idle_task(current)) || | |
6151 | system_state == SYSTEM_BOOTING || system_state > SYSTEM_RUNNING || | |
6152 | oops_in_progress) | |
6153 | return; | |
6154 | ||
6155 | if (time_before(jiffies, prev_jiffy + HZ) && prev_jiffy) | |
6156 | return; | |
6157 | prev_jiffy = jiffies; | |
6158 | ||
6159 | /* Save this before calling printk(), since that will clobber it: */ | |
6160 | preempt_disable_ip = get_preempt_disable_ip(current); | |
6161 | ||
6162 | printk(KERN_ERR | |
6163 | "BUG: sleeping function called from invalid context at %s:%d\n", | |
6164 | file, line); | |
6165 | printk(KERN_ERR | |
6166 | "in_atomic(): %d, irqs_disabled(): %d, pid: %d, name: %s\n", | |
6167 | in_atomic(), irqs_disabled(), | |
6168 | current->pid, current->comm); | |
6169 | ||
6170 | if (task_stack_end_corrupted(current)) | |
6171 | printk(KERN_EMERG "Thread overran stack, or stack corrupted\n"); | |
6172 | ||
6173 | debug_show_held_locks(current); | |
6174 | if (irqs_disabled()) | |
6175 | print_irqtrace_events(current); | |
6176 | if (IS_ENABLED(CONFIG_DEBUG_PREEMPT) | |
6177 | && !preempt_count_equals(preempt_offset)) { | |
6178 | pr_err("Preemption disabled at:"); | |
6179 | print_ip_sym(preempt_disable_ip); | |
6180 | pr_cont("\n"); | |
6181 | } | |
6182 | dump_stack(); | |
6183 | add_taint(TAINT_WARN, LOCKDEP_STILL_OK); | |
6184 | } | |
6185 | EXPORT_SYMBOL(___might_sleep); | |
6186 | #endif | |
6187 | ||
6188 | #ifdef CONFIG_MAGIC_SYSRQ | |
6189 | void normalize_rt_tasks(void) | |
6190 | { | |
6191 | struct task_struct *g, *p; | |
6192 | struct sched_attr attr = { | |
6193 | .sched_policy = SCHED_NORMAL, | |
6194 | }; | |
6195 | ||
6196 | read_lock(&tasklist_lock); | |
6197 | for_each_process_thread(g, p) { | |
6198 | /* | |
6199 | * Only normalize user tasks: | |
6200 | */ | |
6201 | if (p->flags & PF_KTHREAD) | |
6202 | continue; | |
6203 | ||
6204 | p->se.exec_start = 0; | |
6205 | schedstat_set(p->se.statistics.wait_start, 0); | |
6206 | schedstat_set(p->se.statistics.sleep_start, 0); | |
6207 | schedstat_set(p->se.statistics.block_start, 0); | |
6208 | ||
6209 | if (!dl_task(p) && !rt_task(p)) { | |
6210 | /* | |
6211 | * Renice negative nice level userspace | |
6212 | * tasks back to 0: | |
6213 | */ | |
6214 | if (task_nice(p) < 0) | |
6215 | set_user_nice(p, 0); | |
6216 | continue; | |
6217 | } | |
6218 | ||
6219 | __sched_setscheduler(p, &attr, false, false); | |
6220 | } | |
6221 | read_unlock(&tasklist_lock); | |
6222 | } | |
6223 | ||
6224 | #endif /* CONFIG_MAGIC_SYSRQ */ | |
6225 | ||
6226 | #if defined(CONFIG_IA64) || defined(CONFIG_KGDB_KDB) | |
6227 | /* | |
6228 | * These functions are only useful for the IA64 MCA handling, or kdb. | |
6229 | * | |
6230 | * They can only be called when the whole system has been | |
6231 | * stopped - every CPU needs to be quiescent, and no scheduling | |
6232 | * activity can take place. Using them for anything else would | |
6233 | * be a serious bug, and as a result, they aren't even visible | |
6234 | * under any other configuration. | |
6235 | */ | |
6236 | ||
6237 | /** | |
6238 | * curr_task - return the current task for a given CPU. | |
6239 | * @cpu: the processor in question. | |
6240 | * | |
6241 | * ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED! | |
6242 | * | |
6243 | * Return: The current task for @cpu. | |
6244 | */ | |
6245 | struct task_struct *curr_task(int cpu) | |
6246 | { | |
6247 | return cpu_curr(cpu); | |
6248 | } | |
6249 | ||
6250 | #endif /* defined(CONFIG_IA64) || defined(CONFIG_KGDB_KDB) */ | |
6251 | ||
6252 | #ifdef CONFIG_IA64 | |
6253 | /** | |
6254 | * set_curr_task - set the current task for a given CPU. | |
6255 | * @cpu: the processor in question. | |
6256 | * @p: the task pointer to set. | |
6257 | * | |
6258 | * Description: This function must only be used when non-maskable interrupts | |
6259 | * are serviced on a separate stack. It allows the architecture to switch the | |
6260 | * notion of the current task on a CPU in a non-blocking manner. This function | |
6261 | * must be called with all CPU's synchronized, and interrupts disabled, the | |
6262 | * and caller must save the original value of the current task (see | |
6263 | * curr_task() above) and restore that value before reenabling interrupts and | |
6264 | * re-starting the system. | |
6265 | * | |
6266 | * ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED! | |
6267 | */ | |
6268 | void ia64_set_curr_task(int cpu, struct task_struct *p) | |
6269 | { | |
6270 | cpu_curr(cpu) = p; | |
6271 | } | |
6272 | ||
6273 | #endif | |
6274 | ||
6275 | #ifdef CONFIG_CGROUP_SCHED | |
6276 | /* task_group_lock serializes the addition/removal of task groups */ | |
6277 | static DEFINE_SPINLOCK(task_group_lock); | |
6278 | ||
6279 | static void sched_free_group(struct task_group *tg) | |
6280 | { | |
6281 | free_fair_sched_group(tg); | |
6282 | free_rt_sched_group(tg); | |
6283 | autogroup_free(tg); | |
6284 | kmem_cache_free(task_group_cache, tg); | |
6285 | } | |
6286 | ||
6287 | /* allocate runqueue etc for a new task group */ | |
6288 | struct task_group *sched_create_group(struct task_group *parent) | |
6289 | { | |
6290 | struct task_group *tg; | |
6291 | ||
6292 | tg = kmem_cache_alloc(task_group_cache, GFP_KERNEL | __GFP_ZERO); | |
6293 | if (!tg) | |
6294 | return ERR_PTR(-ENOMEM); | |
6295 | ||
6296 | if (!alloc_fair_sched_group(tg, parent)) | |
6297 | goto err; | |
6298 | ||
6299 | if (!alloc_rt_sched_group(tg, parent)) | |
6300 | goto err; | |
6301 | ||
6302 | return tg; | |
6303 | ||
6304 | err: | |
6305 | sched_free_group(tg); | |
6306 | return ERR_PTR(-ENOMEM); | |
6307 | } | |
6308 | ||
6309 | void sched_online_group(struct task_group *tg, struct task_group *parent) | |
6310 | { | |
6311 | unsigned long flags; | |
6312 | ||
6313 | spin_lock_irqsave(&task_group_lock, flags); | |
6314 | list_add_rcu(&tg->list, &task_groups); | |
6315 | ||
6316 | /* Root should already exist: */ | |
6317 | WARN_ON(!parent); | |
6318 | ||
6319 | tg->parent = parent; | |
6320 | INIT_LIST_HEAD(&tg->children); | |
6321 | list_add_rcu(&tg->siblings, &parent->children); | |
6322 | spin_unlock_irqrestore(&task_group_lock, flags); | |
6323 | ||
6324 | online_fair_sched_group(tg); | |
6325 | } | |
6326 | ||
6327 | /* rcu callback to free various structures associated with a task group */ | |
6328 | static void sched_free_group_rcu(struct rcu_head *rhp) | |
6329 | { | |
6330 | /* Now it should be safe to free those cfs_rqs: */ | |
6331 | sched_free_group(container_of(rhp, struct task_group, rcu)); | |
6332 | } | |
6333 | ||
6334 | void sched_destroy_group(struct task_group *tg) | |
6335 | { | |
6336 | /* Wait for possible concurrent references to cfs_rqs complete: */ | |
6337 | call_rcu(&tg->rcu, sched_free_group_rcu); | |
6338 | } | |
6339 | ||
6340 | void sched_offline_group(struct task_group *tg) | |
6341 | { | |
6342 | unsigned long flags; | |
6343 | ||
6344 | /* End participation in shares distribution: */ | |
6345 | unregister_fair_sched_group(tg); | |
6346 | ||
6347 | spin_lock_irqsave(&task_group_lock, flags); | |
6348 | list_del_rcu(&tg->list); | |
6349 | list_del_rcu(&tg->siblings); | |
6350 | spin_unlock_irqrestore(&task_group_lock, flags); | |
6351 | } | |
6352 | ||
6353 | static void sched_change_group(struct task_struct *tsk, int type) | |
6354 | { | |
6355 | struct task_group *tg; | |
6356 | ||
6357 | /* | |
6358 | * All callers are synchronized by task_rq_lock(); we do not use RCU | |
6359 | * which is pointless here. Thus, we pass "true" to task_css_check() | |
6360 | * to prevent lockdep warnings. | |
6361 | */ | |
6362 | tg = container_of(task_css_check(tsk, cpu_cgrp_id, true), | |
6363 | struct task_group, css); | |
6364 | tg = autogroup_task_group(tsk, tg); | |
6365 | tsk->sched_task_group = tg; | |
6366 | ||
6367 | #ifdef CONFIG_FAIR_GROUP_SCHED | |
6368 | if (tsk->sched_class->task_change_group) | |
6369 | tsk->sched_class->task_change_group(tsk, type); | |
6370 | else | |
6371 | #endif | |
6372 | set_task_rq(tsk, task_cpu(tsk)); | |
6373 | } | |
6374 | ||
6375 | /* | |
6376 | * Change task's runqueue when it moves between groups. | |
6377 | * | |
6378 | * The caller of this function should have put the task in its new group by | |
6379 | * now. This function just updates tsk->se.cfs_rq and tsk->se.parent to reflect | |
6380 | * its new group. | |
6381 | */ | |
6382 | void sched_move_task(struct task_struct *tsk) | |
6383 | { | |
6384 | int queued, running, queue_flags = | |
6385 | DEQUEUE_SAVE | DEQUEUE_MOVE | DEQUEUE_NOCLOCK; | |
6386 | struct rq_flags rf; | |
6387 | struct rq *rq; | |
6388 | ||
6389 | rq = task_rq_lock(tsk, &rf); | |
6390 | update_rq_clock(rq); | |
6391 | ||
6392 | running = task_current(rq, tsk); | |
6393 | queued = task_on_rq_queued(tsk); | |
6394 | ||
6395 | if (queued) | |
6396 | dequeue_task(rq, tsk, queue_flags); | |
6397 | if (running) | |
6398 | put_prev_task(rq, tsk); | |
6399 | ||
6400 | sched_change_group(tsk, TASK_MOVE_GROUP); | |
6401 | ||
6402 | if (queued) | |
6403 | enqueue_task(rq, tsk, queue_flags); | |
6404 | if (running) | |
6405 | set_curr_task(rq, tsk); | |
6406 | ||
6407 | task_rq_unlock(rq, tsk, &rf); | |
6408 | } | |
6409 | ||
6410 | static inline struct task_group *css_tg(struct cgroup_subsys_state *css) | |
6411 | { | |
6412 | return css ? container_of(css, struct task_group, css) : NULL; | |
6413 | } | |
6414 | ||
6415 | static struct cgroup_subsys_state * | |
6416 | cpu_cgroup_css_alloc(struct cgroup_subsys_state *parent_css) | |
6417 | { | |
6418 | struct task_group *parent = css_tg(parent_css); | |
6419 | struct task_group *tg; | |
6420 | ||
6421 | if (!parent) { | |
6422 | /* This is early initialization for the top cgroup */ | |
6423 | return &root_task_group.css; | |
6424 | } | |
6425 | ||
6426 | tg = sched_create_group(parent); | |
6427 | if (IS_ERR(tg)) | |
6428 | return ERR_PTR(-ENOMEM); | |
6429 | ||
6430 | return &tg->css; | |
6431 | } | |
6432 | ||
6433 | /* Expose task group only after completing cgroup initialization */ | |
6434 | static int cpu_cgroup_css_online(struct cgroup_subsys_state *css) | |
6435 | { | |
6436 | struct task_group *tg = css_tg(css); | |
6437 | struct task_group *parent = css_tg(css->parent); | |
6438 | ||
6439 | if (parent) | |
6440 | sched_online_group(tg, parent); | |
6441 | return 0; | |
6442 | } | |
6443 | ||
6444 | static void cpu_cgroup_css_released(struct cgroup_subsys_state *css) | |
6445 | { | |
6446 | struct task_group *tg = css_tg(css); | |
6447 | ||
6448 | sched_offline_group(tg); | |
6449 | } | |
6450 | ||
6451 | static void cpu_cgroup_css_free(struct cgroup_subsys_state *css) | |
6452 | { | |
6453 | struct task_group *tg = css_tg(css); | |
6454 | ||
6455 | /* | |
6456 | * Relies on the RCU grace period between css_released() and this. | |
6457 | */ | |
6458 | sched_free_group(tg); | |
6459 | } | |
6460 | ||
6461 | /* | |
6462 | * This is called before wake_up_new_task(), therefore we really only | |
6463 | * have to set its group bits, all the other stuff does not apply. | |
6464 | */ | |
6465 | static void cpu_cgroup_fork(struct task_struct *task) | |
6466 | { | |
6467 | struct rq_flags rf; | |
6468 | struct rq *rq; | |
6469 | ||
6470 | rq = task_rq_lock(task, &rf); | |
6471 | ||
6472 | update_rq_clock(rq); | |
6473 | sched_change_group(task, TASK_SET_GROUP); | |
6474 | ||
6475 | task_rq_unlock(rq, task, &rf); | |
6476 | } | |
6477 | ||
6478 | static int cpu_cgroup_can_attach(struct cgroup_taskset *tset) | |
6479 | { | |
6480 | struct task_struct *task; | |
6481 | struct cgroup_subsys_state *css; | |
6482 | int ret = 0; | |
6483 | ||
6484 | cgroup_taskset_for_each(task, css, tset) { | |
6485 | #ifdef CONFIG_RT_GROUP_SCHED | |
6486 | if (!sched_rt_can_attach(css_tg(css), task)) | |
6487 | return -EINVAL; | |
6488 | #else | |
6489 | /* We don't support RT-tasks being in separate groups */ | |
6490 | if (task->sched_class != &fair_sched_class) | |
6491 | return -EINVAL; | |
6492 | #endif | |
6493 | /* | |
6494 | * Serialize against wake_up_new_task() such that if its | |
6495 | * running, we're sure to observe its full state. | |
6496 | */ | |
6497 | raw_spin_lock_irq(&task->pi_lock); | |
6498 | /* | |
6499 | * Avoid calling sched_move_task() before wake_up_new_task() | |
6500 | * has happened. This would lead to problems with PELT, due to | |
6501 | * move wanting to detach+attach while we're not attached yet. | |
6502 | */ | |
6503 | if (task->state == TASK_NEW) | |
6504 | ret = -EINVAL; | |
6505 | raw_spin_unlock_irq(&task->pi_lock); | |
6506 | ||
6507 | if (ret) | |
6508 | break; | |
6509 | } | |
6510 | return ret; | |
6511 | } | |
6512 | ||
6513 | static void cpu_cgroup_attach(struct cgroup_taskset *tset) | |
6514 | { | |
6515 | struct task_struct *task; | |
6516 | struct cgroup_subsys_state *css; | |
6517 | ||
6518 | cgroup_taskset_for_each(task, css, tset) | |
6519 | sched_move_task(task); | |
6520 | } | |
6521 | ||
6522 | #ifdef CONFIG_FAIR_GROUP_SCHED | |
6523 | static int cpu_shares_write_u64(struct cgroup_subsys_state *css, | |
6524 | struct cftype *cftype, u64 shareval) | |
6525 | { | |
6526 | return sched_group_set_shares(css_tg(css), scale_load(shareval)); | |
6527 | } | |
6528 | ||
6529 | static u64 cpu_shares_read_u64(struct cgroup_subsys_state *css, | |
6530 | struct cftype *cft) | |
6531 | { | |
6532 | struct task_group *tg = css_tg(css); | |
6533 | ||
6534 | return (u64) scale_load_down(tg->shares); | |
6535 | } | |
6536 | ||
6537 | #ifdef CONFIG_CFS_BANDWIDTH | |
6538 | static DEFINE_MUTEX(cfs_constraints_mutex); | |
6539 | ||
6540 | const u64 max_cfs_quota_period = 1 * NSEC_PER_SEC; /* 1s */ | |
6541 | const u64 min_cfs_quota_period = 1 * NSEC_PER_MSEC; /* 1ms */ | |
6542 | ||
6543 | static int __cfs_schedulable(struct task_group *tg, u64 period, u64 runtime); | |
6544 | ||
6545 | static int tg_set_cfs_bandwidth(struct task_group *tg, u64 period, u64 quota) | |
6546 | { | |
6547 | int i, ret = 0, runtime_enabled, runtime_was_enabled; | |
6548 | struct cfs_bandwidth *cfs_b = &tg->cfs_bandwidth; | |
6549 | ||
6550 | if (tg == &root_task_group) | |
6551 | return -EINVAL; | |
6552 | ||
6553 | /* | |
6554 | * Ensure we have at some amount of bandwidth every period. This is | |
6555 | * to prevent reaching a state of large arrears when throttled via | |
6556 | * entity_tick() resulting in prolonged exit starvation. | |
6557 | */ | |
6558 | if (quota < min_cfs_quota_period || period < min_cfs_quota_period) | |
6559 | return -EINVAL; | |
6560 | ||
6561 | /* | |
6562 | * Likewise, bound things on the otherside by preventing insane quota | |
6563 | * periods. This also allows us to normalize in computing quota | |
6564 | * feasibility. | |
6565 | */ | |
6566 | if (period > max_cfs_quota_period) | |
6567 | return -EINVAL; | |
6568 | ||
6569 | /* | |
6570 | * Prevent race between setting of cfs_rq->runtime_enabled and | |
6571 | * unthrottle_offline_cfs_rqs(). | |
6572 | */ | |
6573 | get_online_cpus(); | |
6574 | mutex_lock(&cfs_constraints_mutex); | |
6575 | ret = __cfs_schedulable(tg, period, quota); | |
6576 | if (ret) | |
6577 | goto out_unlock; | |
6578 | ||
6579 | runtime_enabled = quota != RUNTIME_INF; | |
6580 | runtime_was_enabled = cfs_b->quota != RUNTIME_INF; | |
6581 | /* | |
6582 | * If we need to toggle cfs_bandwidth_used, off->on must occur | |
6583 | * before making related changes, and on->off must occur afterwards | |
6584 | */ | |
6585 | if (runtime_enabled && !runtime_was_enabled) | |
6586 | cfs_bandwidth_usage_inc(); | |
6587 | raw_spin_lock_irq(&cfs_b->lock); | |
6588 | cfs_b->period = ns_to_ktime(period); | |
6589 | cfs_b->quota = quota; | |
6590 | ||
6591 | __refill_cfs_bandwidth_runtime(cfs_b); | |
6592 | ||
6593 | /* Restart the period timer (if active) to handle new period expiry: */ | |
6594 | if (runtime_enabled) | |
6595 | start_cfs_bandwidth(cfs_b); | |
6596 | ||
6597 | raw_spin_unlock_irq(&cfs_b->lock); | |
6598 | ||
6599 | for_each_online_cpu(i) { | |
6600 | struct cfs_rq *cfs_rq = tg->cfs_rq[i]; | |
6601 | struct rq *rq = cfs_rq->rq; | |
6602 | struct rq_flags rf; | |
6603 | ||
6604 | rq_lock_irq(rq, &rf); | |
6605 | cfs_rq->runtime_enabled = runtime_enabled; | |
6606 | cfs_rq->runtime_remaining = 0; | |
6607 | ||
6608 | if (cfs_rq->throttled) | |
6609 | unthrottle_cfs_rq(cfs_rq); | |
6610 | rq_unlock_irq(rq, &rf); | |
6611 | } | |
6612 | if (runtime_was_enabled && !runtime_enabled) | |
6613 | cfs_bandwidth_usage_dec(); | |
6614 | out_unlock: | |
6615 | mutex_unlock(&cfs_constraints_mutex); | |
6616 | put_online_cpus(); | |
6617 | ||
6618 | return ret; | |
6619 | } | |
6620 | ||
6621 | int tg_set_cfs_quota(struct task_group *tg, long cfs_quota_us) | |
6622 | { | |
6623 | u64 quota, period; | |
6624 | ||
6625 | period = ktime_to_ns(tg->cfs_bandwidth.period); | |
6626 | if (cfs_quota_us < 0) | |
6627 | quota = RUNTIME_INF; | |
6628 | else | |
6629 | quota = (u64)cfs_quota_us * NSEC_PER_USEC; | |
6630 | ||
6631 | return tg_set_cfs_bandwidth(tg, period, quota); | |
6632 | } | |
6633 | ||
6634 | long tg_get_cfs_quota(struct task_group *tg) | |
6635 | { | |
6636 | u64 quota_us; | |
6637 | ||
6638 | if (tg->cfs_bandwidth.quota == RUNTIME_INF) | |
6639 | return -1; | |
6640 | ||
6641 | quota_us = tg->cfs_bandwidth.quota; | |
6642 | do_div(quota_us, NSEC_PER_USEC); | |
6643 | ||
6644 | return quota_us; | |
6645 | } | |
6646 | ||
6647 | int tg_set_cfs_period(struct task_group *tg, long cfs_period_us) | |
6648 | { | |
6649 | u64 quota, period; | |
6650 | ||
6651 | period = (u64)cfs_period_us * NSEC_PER_USEC; | |
6652 | quota = tg->cfs_bandwidth.quota; | |
6653 | ||
6654 | return tg_set_cfs_bandwidth(tg, period, quota); | |
6655 | } | |
6656 | ||
6657 | long tg_get_cfs_period(struct task_group *tg) | |
6658 | { | |
6659 | u64 cfs_period_us; | |
6660 | ||
6661 | cfs_period_us = ktime_to_ns(tg->cfs_bandwidth.period); | |
6662 | do_div(cfs_period_us, NSEC_PER_USEC); | |
6663 | ||
6664 | return cfs_period_us; | |
6665 | } | |
6666 | ||
6667 | static s64 cpu_cfs_quota_read_s64(struct cgroup_subsys_state *css, | |
6668 | struct cftype *cft) | |
6669 | { | |
6670 | return tg_get_cfs_quota(css_tg(css)); | |
6671 | } | |
6672 | ||
6673 | static int cpu_cfs_quota_write_s64(struct cgroup_subsys_state *css, | |
6674 | struct cftype *cftype, s64 cfs_quota_us) | |
6675 | { | |
6676 | return tg_set_cfs_quota(css_tg(css), cfs_quota_us); | |
6677 | } | |
6678 | ||
6679 | static u64 cpu_cfs_period_read_u64(struct cgroup_subsys_state *css, | |
6680 | struct cftype *cft) | |
6681 | { | |
6682 | return tg_get_cfs_period(css_tg(css)); | |
6683 | } | |
6684 | ||
6685 | static int cpu_cfs_period_write_u64(struct cgroup_subsys_state *css, | |
6686 | struct cftype *cftype, u64 cfs_period_us) | |
6687 | { | |
6688 | return tg_set_cfs_period(css_tg(css), cfs_period_us); | |
6689 | } | |
6690 | ||
6691 | struct cfs_schedulable_data { | |
6692 | struct task_group *tg; | |
6693 | u64 period, quota; | |
6694 | }; | |
6695 | ||
6696 | /* | |
6697 | * normalize group quota/period to be quota/max_period | |
6698 | * note: units are usecs | |
6699 | */ | |
6700 | static u64 normalize_cfs_quota(struct task_group *tg, | |
6701 | struct cfs_schedulable_data *d) | |
6702 | { | |
6703 | u64 quota, period; | |
6704 | ||
6705 | if (tg == d->tg) { | |
6706 | period = d->period; | |
6707 | quota = d->quota; | |
6708 | } else { | |
6709 | period = tg_get_cfs_period(tg); | |
6710 | quota = tg_get_cfs_quota(tg); | |
6711 | } | |
6712 | ||
6713 | /* note: these should typically be equivalent */ | |
6714 | if (quota == RUNTIME_INF || quota == -1) | |
6715 | return RUNTIME_INF; | |
6716 | ||
6717 | return to_ratio(period, quota); | |
6718 | } | |
6719 | ||
6720 | static int tg_cfs_schedulable_down(struct task_group *tg, void *data) | |
6721 | { | |
6722 | struct cfs_schedulable_data *d = data; | |
6723 | struct cfs_bandwidth *cfs_b = &tg->cfs_bandwidth; | |
6724 | s64 quota = 0, parent_quota = -1; | |
6725 | ||
6726 | if (!tg->parent) { | |
6727 | quota = RUNTIME_INF; | |
6728 | } else { | |
6729 | struct cfs_bandwidth *parent_b = &tg->parent->cfs_bandwidth; | |
6730 | ||
6731 | quota = normalize_cfs_quota(tg, d); | |
6732 | parent_quota = parent_b->hierarchical_quota; | |
6733 | ||
6734 | /* | |
6735 | * Ensure max(child_quota) <= parent_quota, inherit when no | |
6736 | * limit is set: | |
6737 | */ | |
6738 | if (quota == RUNTIME_INF) | |
6739 | quota = parent_quota; | |
6740 | else if (parent_quota != RUNTIME_INF && quota > parent_quota) | |
6741 | return -EINVAL; | |
6742 | } | |
6743 | cfs_b->hierarchical_quota = quota; | |
6744 | ||
6745 | return 0; | |
6746 | } | |
6747 | ||
6748 | static int __cfs_schedulable(struct task_group *tg, u64 period, u64 quota) | |
6749 | { | |
6750 | int ret; | |
6751 | struct cfs_schedulable_data data = { | |
6752 | .tg = tg, | |
6753 | .period = period, | |
6754 | .quota = quota, | |
6755 | }; | |
6756 | ||
6757 | if (quota != RUNTIME_INF) { | |
6758 | do_div(data.period, NSEC_PER_USEC); | |
6759 | do_div(data.quota, NSEC_PER_USEC); | |
6760 | } | |
6761 | ||
6762 | rcu_read_lock(); | |
6763 | ret = walk_tg_tree(tg_cfs_schedulable_down, tg_nop, &data); | |
6764 | rcu_read_unlock(); | |
6765 | ||
6766 | return ret; | |
6767 | } | |
6768 | ||
6769 | static int cpu_cfs_stat_show(struct seq_file *sf, void *v) | |
6770 | { | |
6771 | struct task_group *tg = css_tg(seq_css(sf)); | |
6772 | struct cfs_bandwidth *cfs_b = &tg->cfs_bandwidth; | |
6773 | ||
6774 | seq_printf(sf, "nr_periods %d\n", cfs_b->nr_periods); | |
6775 | seq_printf(sf, "nr_throttled %d\n", cfs_b->nr_throttled); | |
6776 | seq_printf(sf, "throttled_time %llu\n", cfs_b->throttled_time); | |
6777 | ||
6778 | return 0; | |
6779 | } | |
6780 | #endif /* CONFIG_CFS_BANDWIDTH */ | |
6781 | #endif /* CONFIG_FAIR_GROUP_SCHED */ | |
6782 | ||
6783 | #ifdef CONFIG_RT_GROUP_SCHED | |
6784 | static int cpu_rt_runtime_write(struct cgroup_subsys_state *css, | |
6785 | struct cftype *cft, s64 val) | |
6786 | { | |
6787 | return sched_group_set_rt_runtime(css_tg(css), val); | |
6788 | } | |
6789 | ||
6790 | static s64 cpu_rt_runtime_read(struct cgroup_subsys_state *css, | |
6791 | struct cftype *cft) | |
6792 | { | |
6793 | return sched_group_rt_runtime(css_tg(css)); | |
6794 | } | |
6795 | ||
6796 | static int cpu_rt_period_write_uint(struct cgroup_subsys_state *css, | |
6797 | struct cftype *cftype, u64 rt_period_us) | |
6798 | { | |
6799 | return sched_group_set_rt_period(css_tg(css), rt_period_us); | |
6800 | } | |
6801 | ||
6802 | static u64 cpu_rt_period_read_uint(struct cgroup_subsys_state *css, | |
6803 | struct cftype *cft) | |
6804 | { | |
6805 | return sched_group_rt_period(css_tg(css)); | |
6806 | } | |
6807 | #endif /* CONFIG_RT_GROUP_SCHED */ | |
6808 | ||
6809 | static struct cftype cpu_legacy_files[] = { | |
6810 | #ifdef CONFIG_FAIR_GROUP_SCHED | |
6811 | { | |
6812 | .name = "shares", | |
6813 | .read_u64 = cpu_shares_read_u64, | |
6814 | .write_u64 = cpu_shares_write_u64, | |
6815 | }, | |
6816 | #endif | |
6817 | #ifdef CONFIG_CFS_BANDWIDTH | |
6818 | { | |
6819 | .name = "cfs_quota_us", | |
6820 | .read_s64 = cpu_cfs_quota_read_s64, | |
6821 | .write_s64 = cpu_cfs_quota_write_s64, | |
6822 | }, | |
6823 | { | |
6824 | .name = "cfs_period_us", | |
6825 | .read_u64 = cpu_cfs_period_read_u64, | |
6826 | .write_u64 = cpu_cfs_period_write_u64, | |
6827 | }, | |
6828 | { | |
6829 | .name = "stat", | |
6830 | .seq_show = cpu_cfs_stat_show, | |
6831 | }, | |
6832 | #endif | |
6833 | #ifdef CONFIG_RT_GROUP_SCHED | |
6834 | { | |
6835 | .name = "rt_runtime_us", | |
6836 | .read_s64 = cpu_rt_runtime_read, | |
6837 | .write_s64 = cpu_rt_runtime_write, | |
6838 | }, | |
6839 | { | |
6840 | .name = "rt_period_us", | |
6841 | .read_u64 = cpu_rt_period_read_uint, | |
6842 | .write_u64 = cpu_rt_period_write_uint, | |
6843 | }, | |
6844 | #endif | |
6845 | { } /* Terminate */ | |
6846 | }; | |
6847 | ||
6848 | static int cpu_extra_stat_show(struct seq_file *sf, | |
6849 | struct cgroup_subsys_state *css) | |
6850 | { | |
6851 | #ifdef CONFIG_CFS_BANDWIDTH | |
6852 | { | |
6853 | struct task_group *tg = css_tg(css); | |
6854 | struct cfs_bandwidth *cfs_b = &tg->cfs_bandwidth; | |
6855 | u64 throttled_usec; | |
6856 | ||
6857 | throttled_usec = cfs_b->throttled_time; | |
6858 | do_div(throttled_usec, NSEC_PER_USEC); | |
6859 | ||
6860 | seq_printf(sf, "nr_periods %d\n" | |
6861 | "nr_throttled %d\n" | |
6862 | "throttled_usec %llu\n", | |
6863 | cfs_b->nr_periods, cfs_b->nr_throttled, | |
6864 | throttled_usec); | |
6865 | } | |
6866 | #endif | |
6867 | return 0; | |
6868 | } | |
6869 | ||
6870 | #ifdef CONFIG_FAIR_GROUP_SCHED | |
6871 | static u64 cpu_weight_read_u64(struct cgroup_subsys_state *css, | |
6872 | struct cftype *cft) | |
6873 | { | |
6874 | struct task_group *tg = css_tg(css); | |
6875 | u64 weight = scale_load_down(tg->shares); | |
6876 | ||
6877 | return DIV_ROUND_CLOSEST_ULL(weight * CGROUP_WEIGHT_DFL, 1024); | |
6878 | } | |
6879 | ||
6880 | static int cpu_weight_write_u64(struct cgroup_subsys_state *css, | |
6881 | struct cftype *cft, u64 weight) | |
6882 | { | |
6883 | /* | |
6884 | * cgroup weight knobs should use the common MIN, DFL and MAX | |
6885 | * values which are 1, 100 and 10000 respectively. While it loses | |
6886 | * a bit of range on both ends, it maps pretty well onto the shares | |
6887 | * value used by scheduler and the round-trip conversions preserve | |
6888 | * the original value over the entire range. | |
6889 | */ | |
6890 | if (weight < CGROUP_WEIGHT_MIN || weight > CGROUP_WEIGHT_MAX) | |
6891 | return -ERANGE; | |
6892 | ||
6893 | weight = DIV_ROUND_CLOSEST_ULL(weight * 1024, CGROUP_WEIGHT_DFL); | |
6894 | ||
6895 | return sched_group_set_shares(css_tg(css), scale_load(weight)); | |
6896 | } | |
6897 | ||
6898 | static s64 cpu_weight_nice_read_s64(struct cgroup_subsys_state *css, | |
6899 | struct cftype *cft) | |
6900 | { | |
6901 | unsigned long weight = scale_load_down(css_tg(css)->shares); | |
6902 | int last_delta = INT_MAX; | |
6903 | int prio, delta; | |
6904 | ||
6905 | /* find the closest nice value to the current weight */ | |
6906 | for (prio = 0; prio < ARRAY_SIZE(sched_prio_to_weight); prio++) { | |
6907 | delta = abs(sched_prio_to_weight[prio] - weight); | |
6908 | if (delta >= last_delta) | |
6909 | break; | |
6910 | last_delta = delta; | |
6911 | } | |
6912 | ||
6913 | return PRIO_TO_NICE(prio - 1 + MAX_RT_PRIO); | |
6914 | } | |
6915 | ||
6916 | static int cpu_weight_nice_write_s64(struct cgroup_subsys_state *css, | |
6917 | struct cftype *cft, s64 nice) | |
6918 | { | |
6919 | unsigned long weight; | |
6920 | ||
6921 | if (nice < MIN_NICE || nice > MAX_NICE) | |
6922 | return -ERANGE; | |
6923 | ||
6924 | weight = sched_prio_to_weight[NICE_TO_PRIO(nice) - MAX_RT_PRIO]; | |
6925 | return sched_group_set_shares(css_tg(css), scale_load(weight)); | |
6926 | } | |
6927 | #endif | |
6928 | ||
6929 | static void __maybe_unused cpu_period_quota_print(struct seq_file *sf, | |
6930 | long period, long quota) | |
6931 | { | |
6932 | if (quota < 0) | |
6933 | seq_puts(sf, "max"); | |
6934 | else | |
6935 | seq_printf(sf, "%ld", quota); | |
6936 | ||
6937 | seq_printf(sf, " %ld\n", period); | |
6938 | } | |
6939 | ||
6940 | /* caller should put the current value in *@periodp before calling */ | |
6941 | static int __maybe_unused cpu_period_quota_parse(char *buf, | |
6942 | u64 *periodp, u64 *quotap) | |
6943 | { | |
6944 | char tok[21]; /* U64_MAX */ | |
6945 | ||
6946 | if (!sscanf(buf, "%s %llu", tok, periodp)) | |
6947 | return -EINVAL; | |
6948 | ||
6949 | *periodp *= NSEC_PER_USEC; | |
6950 | ||
6951 | if (sscanf(tok, "%llu", quotap)) | |
6952 | *quotap *= NSEC_PER_USEC; | |
6953 | else if (!strcmp(tok, "max")) | |
6954 | *quotap = RUNTIME_INF; | |
6955 | else | |
6956 | return -EINVAL; | |
6957 | ||
6958 | return 0; | |
6959 | } | |
6960 | ||
6961 | #ifdef CONFIG_CFS_BANDWIDTH | |
6962 | static int cpu_max_show(struct seq_file *sf, void *v) | |
6963 | { | |
6964 | struct task_group *tg = css_tg(seq_css(sf)); | |
6965 | ||
6966 | cpu_period_quota_print(sf, tg_get_cfs_period(tg), tg_get_cfs_quota(tg)); | |
6967 | return 0; | |
6968 | } | |
6969 | ||
6970 | static ssize_t cpu_max_write(struct kernfs_open_file *of, | |
6971 | char *buf, size_t nbytes, loff_t off) | |
6972 | { | |
6973 | struct task_group *tg = css_tg(of_css(of)); | |
6974 | u64 period = tg_get_cfs_period(tg); | |
6975 | u64 quota; | |
6976 | int ret; | |
6977 | ||
6978 | ret = cpu_period_quota_parse(buf, &period, "a); | |
6979 | if (!ret) | |
6980 | ret = tg_set_cfs_bandwidth(tg, period, quota); | |
6981 | return ret ?: nbytes; | |
6982 | } | |
6983 | #endif | |
6984 | ||
6985 | static struct cftype cpu_files[] = { | |
6986 | #ifdef CONFIG_FAIR_GROUP_SCHED | |
6987 | { | |
6988 | .name = "weight", | |
6989 | .flags = CFTYPE_NOT_ON_ROOT, | |
6990 | .read_u64 = cpu_weight_read_u64, | |
6991 | .write_u64 = cpu_weight_write_u64, | |
6992 | }, | |
6993 | { | |
6994 | .name = "weight.nice", | |
6995 | .flags = CFTYPE_NOT_ON_ROOT, | |
6996 | .read_s64 = cpu_weight_nice_read_s64, | |
6997 | .write_s64 = cpu_weight_nice_write_s64, | |
6998 | }, | |
6999 | #endif | |
7000 | #ifdef CONFIG_CFS_BANDWIDTH | |
7001 | { | |
7002 | .name = "max", | |
7003 | .flags = CFTYPE_NOT_ON_ROOT, | |
7004 | .seq_show = cpu_max_show, | |
7005 | .write = cpu_max_write, | |
7006 | }, | |
7007 | #endif | |
7008 | { } /* terminate */ | |
7009 | }; | |
7010 | ||
7011 | struct cgroup_subsys cpu_cgrp_subsys = { | |
7012 | .css_alloc = cpu_cgroup_css_alloc, | |
7013 | .css_online = cpu_cgroup_css_online, | |
7014 | .css_released = cpu_cgroup_css_released, | |
7015 | .css_free = cpu_cgroup_css_free, | |
7016 | .css_extra_stat_show = cpu_extra_stat_show, | |
7017 | .fork = cpu_cgroup_fork, | |
7018 | .can_attach = cpu_cgroup_can_attach, | |
7019 | .attach = cpu_cgroup_attach, | |
7020 | .legacy_cftypes = cpu_legacy_files, | |
7021 | .dfl_cftypes = cpu_files, | |
7022 | .early_init = true, | |
7023 | .threaded = true, | |
7024 | }; | |
7025 | ||
7026 | #endif /* CONFIG_CGROUP_SCHED */ | |
7027 | ||
7028 | void dump_cpu_task(int cpu) | |
7029 | { | |
7030 | pr_info("Task dump for CPU %d:\n", cpu); | |
7031 | sched_show_task(cpu_curr(cpu)); | |
7032 | } | |
7033 | ||
7034 | /* | |
7035 | * Nice levels are multiplicative, with a gentle 10% change for every | |
7036 | * nice level changed. I.e. when a CPU-bound task goes from nice 0 to | |
7037 | * nice 1, it will get ~10% less CPU time than another CPU-bound task | |
7038 | * that remained on nice 0. | |
7039 | * | |
7040 | * The "10% effect" is relative and cumulative: from _any_ nice level, | |
7041 | * if you go up 1 level, it's -10% CPU usage, if you go down 1 level | |
7042 | * it's +10% CPU usage. (to achieve that we use a multiplier of 1.25. | |
7043 | * If a task goes up by ~10% and another task goes down by ~10% then | |
7044 | * the relative distance between them is ~25%.) | |
7045 | */ | |
7046 | const int sched_prio_to_weight[40] = { | |
7047 | /* -20 */ 88761, 71755, 56483, 46273, 36291, | |
7048 | /* -15 */ 29154, 23254, 18705, 14949, 11916, | |
7049 | /* -10 */ 9548, 7620, 6100, 4904, 3906, | |
7050 | /* -5 */ 3121, 2501, 1991, 1586, 1277, | |
7051 | /* 0 */ 1024, 820, 655, 526, 423, | |
7052 | /* 5 */ 335, 272, 215, 172, 137, | |
7053 | /* 10 */ 110, 87, 70, 56, 45, | |
7054 | /* 15 */ 36, 29, 23, 18, 15, | |
7055 | }; | |
7056 | ||
7057 | /* | |
7058 | * Inverse (2^32/x) values of the sched_prio_to_weight[] array, precalculated. | |
7059 | * | |
7060 | * In cases where the weight does not change often, we can use the | |
7061 | * precalculated inverse to speed up arithmetics by turning divisions | |
7062 | * into multiplications: | |
7063 | */ | |
7064 | const u32 sched_prio_to_wmult[40] = { | |
7065 | /* -20 */ 48388, 59856, 76040, 92818, 118348, | |
7066 | /* -15 */ 147320, 184698, 229616, 287308, 360437, | |
7067 | /* -10 */ 449829, 563644, 704093, 875809, 1099582, | |
7068 | /* -5 */ 1376151, 1717300, 2157191, 2708050, 3363326, | |
7069 | /* 0 */ 4194304, 5237765, 6557202, 8165337, 10153587, | |
7070 | /* 5 */ 12820798, 15790321, 19976592, 24970740, 31350126, | |
7071 | /* 10 */ 39045157, 49367440, 61356676, 76695844, 95443717, | |
7072 | /* 15 */ 119304647, 148102320, 186737708, 238609294, 286331153, | |
7073 | }; | |
7074 | ||
7075 | #undef CREATE_TRACE_POINTS |