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1/*
2 * Real-Time Scheduling Class (mapped to the SCHED_FIFO and SCHED_RR
3 * policies)
4 */
5
6#include "sched.h"
7
8#include <linux/slab.h>
9
10static int do_sched_rt_period_timer(struct rt_bandwidth *rt_b, int overrun);
11
12struct rt_bandwidth def_rt_bandwidth;
13
14static enum hrtimer_restart sched_rt_period_timer(struct hrtimer *timer)
15{
16 struct rt_bandwidth *rt_b =
17 container_of(timer, struct rt_bandwidth, rt_period_timer);
18 ktime_t now;
19 int overrun;
20 int idle = 0;
21
22 for (;;) {
23 now = hrtimer_cb_get_time(timer);
24 overrun = hrtimer_forward(timer, now, rt_b->rt_period);
25
26 if (!overrun)
27 break;
28
29 idle = do_sched_rt_period_timer(rt_b, overrun);
30 }
31
32 return idle ? HRTIMER_NORESTART : HRTIMER_RESTART;
33}
34
35void init_rt_bandwidth(struct rt_bandwidth *rt_b, u64 period, u64 runtime)
36{
37 rt_b->rt_period = ns_to_ktime(period);
38 rt_b->rt_runtime = runtime;
39
40 raw_spin_lock_init(&rt_b->rt_runtime_lock);
41
42 hrtimer_init(&rt_b->rt_period_timer,
43 CLOCK_MONOTONIC, HRTIMER_MODE_REL);
44 rt_b->rt_period_timer.function = sched_rt_period_timer;
45}
46
47static void start_rt_bandwidth(struct rt_bandwidth *rt_b)
48{
49 if (!rt_bandwidth_enabled() || rt_b->rt_runtime == RUNTIME_INF)
50 return;
51
52 if (hrtimer_active(&rt_b->rt_period_timer))
53 return;
54
55 raw_spin_lock(&rt_b->rt_runtime_lock);
56 start_bandwidth_timer(&rt_b->rt_period_timer, rt_b->rt_period);
57 raw_spin_unlock(&rt_b->rt_runtime_lock);
58}
59
60void init_rt_rq(struct rt_rq *rt_rq, struct rq *rq)
61{
62 struct rt_prio_array *array;
63 int i;
64
65 array = &rt_rq->active;
66 for (i = 0; i < MAX_RT_PRIO; i++) {
67 INIT_LIST_HEAD(array->queue + i);
68 __clear_bit(i, array->bitmap);
69 }
70 /* delimiter for bitsearch: */
71 __set_bit(MAX_RT_PRIO, array->bitmap);
72
73#if defined CONFIG_SMP
74 rt_rq->highest_prio.curr = MAX_RT_PRIO;
75 rt_rq->highest_prio.next = MAX_RT_PRIO;
76 rt_rq->rt_nr_migratory = 0;
77 rt_rq->overloaded = 0;
78 plist_head_init(&rt_rq->pushable_tasks);
79#endif
80
81 rt_rq->rt_time = 0;
82 rt_rq->rt_throttled = 0;
83 rt_rq->rt_runtime = 0;
84 raw_spin_lock_init(&rt_rq->rt_runtime_lock);
85}
86
87#ifdef CONFIG_RT_GROUP_SCHED
88static void destroy_rt_bandwidth(struct rt_bandwidth *rt_b)
89{
90 hrtimer_cancel(&rt_b->rt_period_timer);
91}
92
93#define rt_entity_is_task(rt_se) (!(rt_se)->my_q)
94
95static inline struct task_struct *rt_task_of(struct sched_rt_entity *rt_se)
96{
97#ifdef CONFIG_SCHED_DEBUG
98 WARN_ON_ONCE(!rt_entity_is_task(rt_se));
99#endif
100 return container_of(rt_se, struct task_struct, rt);
101}
102
103static inline struct rq *rq_of_rt_rq(struct rt_rq *rt_rq)
104{
105 return rt_rq->rq;
106}
107
108static inline struct rt_rq *rt_rq_of_se(struct sched_rt_entity *rt_se)
109{
110 return rt_se->rt_rq;
111}
112
113void free_rt_sched_group(struct task_group *tg)
114{
115 int i;
116
117 if (tg->rt_se)
118 destroy_rt_bandwidth(&tg->rt_bandwidth);
119
120 for_each_possible_cpu(i) {
121 if (tg->rt_rq)
122 kfree(tg->rt_rq[i]);
123 if (tg->rt_se)
124 kfree(tg->rt_se[i]);
125 }
126
127 kfree(tg->rt_rq);
128 kfree(tg->rt_se);
129}
130
131void init_tg_rt_entry(struct task_group *tg, struct rt_rq *rt_rq,
132 struct sched_rt_entity *rt_se, int cpu,
133 struct sched_rt_entity *parent)
134{
135 struct rq *rq = cpu_rq(cpu);
136
137 rt_rq->highest_prio.curr = MAX_RT_PRIO;
138 rt_rq->rt_nr_boosted = 0;
139 rt_rq->rq = rq;
140 rt_rq->tg = tg;
141
142 tg->rt_rq[cpu] = rt_rq;
143 tg->rt_se[cpu] = rt_se;
144
145 if (!rt_se)
146 return;
147
148 if (!parent)
149 rt_se->rt_rq = &rq->rt;
150 else
151 rt_se->rt_rq = parent->my_q;
152
153 rt_se->my_q = rt_rq;
154 rt_se->parent = parent;
155 INIT_LIST_HEAD(&rt_se->run_list);
156}
157
158int alloc_rt_sched_group(struct task_group *tg, struct task_group *parent)
159{
160 struct rt_rq *rt_rq;
161 struct sched_rt_entity *rt_se;
162 int i;
163
164 tg->rt_rq = kzalloc(sizeof(rt_rq) * nr_cpu_ids, GFP_KERNEL);
165 if (!tg->rt_rq)
166 goto err;
167 tg->rt_se = kzalloc(sizeof(rt_se) * nr_cpu_ids, GFP_KERNEL);
168 if (!tg->rt_se)
169 goto err;
170
171 init_rt_bandwidth(&tg->rt_bandwidth,
172 ktime_to_ns(def_rt_bandwidth.rt_period), 0);
173
174 for_each_possible_cpu(i) {
175 rt_rq = kzalloc_node(sizeof(struct rt_rq),
176 GFP_KERNEL, cpu_to_node(i));
177 if (!rt_rq)
178 goto err;
179
180 rt_se = kzalloc_node(sizeof(struct sched_rt_entity),
181 GFP_KERNEL, cpu_to_node(i));
182 if (!rt_se)
183 goto err_free_rq;
184
185 init_rt_rq(rt_rq, cpu_rq(i));
186 rt_rq->rt_runtime = tg->rt_bandwidth.rt_runtime;
187 init_tg_rt_entry(tg, rt_rq, rt_se, i, parent->rt_se[i]);
188 }
189
190 return 1;
191
192err_free_rq:
193 kfree(rt_rq);
194err:
195 return 0;
196}
197
198#else /* CONFIG_RT_GROUP_SCHED */
199
200#define rt_entity_is_task(rt_se) (1)
201
202static inline struct task_struct *rt_task_of(struct sched_rt_entity *rt_se)
203{
204 return container_of(rt_se, struct task_struct, rt);
205}
206
207static inline struct rq *rq_of_rt_rq(struct rt_rq *rt_rq)
208{
209 return container_of(rt_rq, struct rq, rt);
210}
211
212static inline struct rt_rq *rt_rq_of_se(struct sched_rt_entity *rt_se)
213{
214 struct task_struct *p = rt_task_of(rt_se);
215 struct rq *rq = task_rq(p);
216
217 return &rq->rt;
218}
219
220void free_rt_sched_group(struct task_group *tg) { }
221
222int alloc_rt_sched_group(struct task_group *tg, struct task_group *parent)
223{
224 return 1;
225}
226#endif /* CONFIG_RT_GROUP_SCHED */
227
228#ifdef CONFIG_SMP
229
230static inline int rt_overloaded(struct rq *rq)
231{
232 return atomic_read(&rq->rd->rto_count);
233}
234
235static inline void rt_set_overload(struct rq *rq)
236{
237 if (!rq->online)
238 return;
239
240 cpumask_set_cpu(rq->cpu, rq->rd->rto_mask);
241 /*
242 * Make sure the mask is visible before we set
243 * the overload count. That is checked to determine
244 * if we should look at the mask. It would be a shame
245 * if we looked at the mask, but the mask was not
246 * updated yet.
247 */
248 wmb();
249 atomic_inc(&rq->rd->rto_count);
250}
251
252static inline void rt_clear_overload(struct rq *rq)
253{
254 if (!rq->online)
255 return;
256
257 /* the order here really doesn't matter */
258 atomic_dec(&rq->rd->rto_count);
259 cpumask_clear_cpu(rq->cpu, rq->rd->rto_mask);
260}
261
262static void update_rt_migration(struct rt_rq *rt_rq)
263{
264 if (rt_rq->rt_nr_migratory && rt_rq->rt_nr_total > 1) {
265 if (!rt_rq->overloaded) {
266 rt_set_overload(rq_of_rt_rq(rt_rq));
267 rt_rq->overloaded = 1;
268 }
269 } else if (rt_rq->overloaded) {
270 rt_clear_overload(rq_of_rt_rq(rt_rq));
271 rt_rq->overloaded = 0;
272 }
273}
274
275static void inc_rt_migration(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
276{
277 struct task_struct *p;
278
279 if (!rt_entity_is_task(rt_se))
280 return;
281
282 p = rt_task_of(rt_se);
283 rt_rq = &rq_of_rt_rq(rt_rq)->rt;
284
285 rt_rq->rt_nr_total++;
286 if (p->nr_cpus_allowed > 1)
287 rt_rq->rt_nr_migratory++;
288
289 update_rt_migration(rt_rq);
290}
291
292static void dec_rt_migration(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
293{
294 struct task_struct *p;
295
296 if (!rt_entity_is_task(rt_se))
297 return;
298
299 p = rt_task_of(rt_se);
300 rt_rq = &rq_of_rt_rq(rt_rq)->rt;
301
302 rt_rq->rt_nr_total--;
303 if (p->nr_cpus_allowed > 1)
304 rt_rq->rt_nr_migratory--;
305
306 update_rt_migration(rt_rq);
307}
308
309static inline int has_pushable_tasks(struct rq *rq)
310{
311 return !plist_head_empty(&rq->rt.pushable_tasks);
312}
313
314static void enqueue_pushable_task(struct rq *rq, struct task_struct *p)
315{
316 plist_del(&p->pushable_tasks, &rq->rt.pushable_tasks);
317 plist_node_init(&p->pushable_tasks, p->prio);
318 plist_add(&p->pushable_tasks, &rq->rt.pushable_tasks);
319
320 /* Update the highest prio pushable task */
321 if (p->prio < rq->rt.highest_prio.next)
322 rq->rt.highest_prio.next = p->prio;
323}
324
325static void dequeue_pushable_task(struct rq *rq, struct task_struct *p)
326{
327 plist_del(&p->pushable_tasks, &rq->rt.pushable_tasks);
328
329 /* Update the new highest prio pushable task */
330 if (has_pushable_tasks(rq)) {
331 p = plist_first_entry(&rq->rt.pushable_tasks,
332 struct task_struct, pushable_tasks);
333 rq->rt.highest_prio.next = p->prio;
334 } else
335 rq->rt.highest_prio.next = MAX_RT_PRIO;
336}
337
338#else
339
340static inline void enqueue_pushable_task(struct rq *rq, struct task_struct *p)
341{
342}
343
344static inline void dequeue_pushable_task(struct rq *rq, struct task_struct *p)
345{
346}
347
348static inline
349void inc_rt_migration(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
350{
351}
352
353static inline
354void dec_rt_migration(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
355{
356}
357
358#endif /* CONFIG_SMP */
359
360static inline int on_rt_rq(struct sched_rt_entity *rt_se)
361{
362 return !list_empty(&rt_se->run_list);
363}
364
365#ifdef CONFIG_RT_GROUP_SCHED
366
367static inline u64 sched_rt_runtime(struct rt_rq *rt_rq)
368{
369 if (!rt_rq->tg)
370 return RUNTIME_INF;
371
372 return rt_rq->rt_runtime;
373}
374
375static inline u64 sched_rt_period(struct rt_rq *rt_rq)
376{
377 return ktime_to_ns(rt_rq->tg->rt_bandwidth.rt_period);
378}
379
380typedef struct task_group *rt_rq_iter_t;
381
382static inline struct task_group *next_task_group(struct task_group *tg)
383{
384 do {
385 tg = list_entry_rcu(tg->list.next,
386 typeof(struct task_group), list);
387 } while (&tg->list != &task_groups && task_group_is_autogroup(tg));
388
389 if (&tg->list == &task_groups)
390 tg = NULL;
391
392 return tg;
393}
394
395#define for_each_rt_rq(rt_rq, iter, rq) \
396 for (iter = container_of(&task_groups, typeof(*iter), list); \
397 (iter = next_task_group(iter)) && \
398 (rt_rq = iter->rt_rq[cpu_of(rq)]);)
399
400static inline void list_add_leaf_rt_rq(struct rt_rq *rt_rq)
401{
402 list_add_rcu(&rt_rq->leaf_rt_rq_list,
403 &rq_of_rt_rq(rt_rq)->leaf_rt_rq_list);
404}
405
406static inline void list_del_leaf_rt_rq(struct rt_rq *rt_rq)
407{
408 list_del_rcu(&rt_rq->leaf_rt_rq_list);
409}
410
411#define for_each_leaf_rt_rq(rt_rq, rq) \
412 list_for_each_entry_rcu(rt_rq, &rq->leaf_rt_rq_list, leaf_rt_rq_list)
413
414#define for_each_sched_rt_entity(rt_se) \
415 for (; rt_se; rt_se = rt_se->parent)
416
417static inline struct rt_rq *group_rt_rq(struct sched_rt_entity *rt_se)
418{
419 return rt_se->my_q;
420}
421
422static void enqueue_rt_entity(struct sched_rt_entity *rt_se, bool head);
423static void dequeue_rt_entity(struct sched_rt_entity *rt_se);
424
425static void sched_rt_rq_enqueue(struct rt_rq *rt_rq)
426{
427 struct task_struct *curr = rq_of_rt_rq(rt_rq)->curr;
428 struct sched_rt_entity *rt_se;
429
430 int cpu = cpu_of(rq_of_rt_rq(rt_rq));
431
432 rt_se = rt_rq->tg->rt_se[cpu];
433
434 if (rt_rq->rt_nr_running) {
435 if (rt_se && !on_rt_rq(rt_se))
436 enqueue_rt_entity(rt_se, false);
437 if (rt_rq->highest_prio.curr < curr->prio)
438 resched_task(curr);
439 }
440}
441
442static void sched_rt_rq_dequeue(struct rt_rq *rt_rq)
443{
444 struct sched_rt_entity *rt_se;
445 int cpu = cpu_of(rq_of_rt_rq(rt_rq));
446
447 rt_se = rt_rq->tg->rt_se[cpu];
448
449 if (rt_se && on_rt_rq(rt_se))
450 dequeue_rt_entity(rt_se);
451}
452
453static inline int rt_rq_throttled(struct rt_rq *rt_rq)
454{
455 return rt_rq->rt_throttled && !rt_rq->rt_nr_boosted;
456}
457
458static int rt_se_boosted(struct sched_rt_entity *rt_se)
459{
460 struct rt_rq *rt_rq = group_rt_rq(rt_se);
461 struct task_struct *p;
462
463 if (rt_rq)
464 return !!rt_rq->rt_nr_boosted;
465
466 p = rt_task_of(rt_se);
467 return p->prio != p->normal_prio;
468}
469
470#ifdef CONFIG_SMP
471static inline const struct cpumask *sched_rt_period_mask(void)
472{
473 return cpu_rq(smp_processor_id())->rd->span;
474}
475#else
476static inline const struct cpumask *sched_rt_period_mask(void)
477{
478 return cpu_online_mask;
479}
480#endif
481
482static inline
483struct rt_rq *sched_rt_period_rt_rq(struct rt_bandwidth *rt_b, int cpu)
484{
485 return container_of(rt_b, struct task_group, rt_bandwidth)->rt_rq[cpu];
486}
487
488static inline struct rt_bandwidth *sched_rt_bandwidth(struct rt_rq *rt_rq)
489{
490 return &rt_rq->tg->rt_bandwidth;
491}
492
493#else /* !CONFIG_RT_GROUP_SCHED */
494
495static inline u64 sched_rt_runtime(struct rt_rq *rt_rq)
496{
497 return rt_rq->rt_runtime;
498}
499
500static inline u64 sched_rt_period(struct rt_rq *rt_rq)
501{
502 return ktime_to_ns(def_rt_bandwidth.rt_period);
503}
504
505typedef struct rt_rq *rt_rq_iter_t;
506
507#define for_each_rt_rq(rt_rq, iter, rq) \
508 for ((void) iter, rt_rq = &rq->rt; rt_rq; rt_rq = NULL)
509
510static inline void list_add_leaf_rt_rq(struct rt_rq *rt_rq)
511{
512}
513
514static inline void list_del_leaf_rt_rq(struct rt_rq *rt_rq)
515{
516}
517
518#define for_each_leaf_rt_rq(rt_rq, rq) \
519 for (rt_rq = &rq->rt; rt_rq; rt_rq = NULL)
520
521#define for_each_sched_rt_entity(rt_se) \
522 for (; rt_se; rt_se = NULL)
523
524static inline struct rt_rq *group_rt_rq(struct sched_rt_entity *rt_se)
525{
526 return NULL;
527}
528
529static inline void sched_rt_rq_enqueue(struct rt_rq *rt_rq)
530{
531 if (rt_rq->rt_nr_running)
532 resched_task(rq_of_rt_rq(rt_rq)->curr);
533}
534
535static inline void sched_rt_rq_dequeue(struct rt_rq *rt_rq)
536{
537}
538
539static inline int rt_rq_throttled(struct rt_rq *rt_rq)
540{
541 return rt_rq->rt_throttled;
542}
543
544static inline const struct cpumask *sched_rt_period_mask(void)
545{
546 return cpu_online_mask;
547}
548
549static inline
550struct rt_rq *sched_rt_period_rt_rq(struct rt_bandwidth *rt_b, int cpu)
551{
552 return &cpu_rq(cpu)->rt;
553}
554
555static inline struct rt_bandwidth *sched_rt_bandwidth(struct rt_rq *rt_rq)
556{
557 return &def_rt_bandwidth;
558}
559
560#endif /* CONFIG_RT_GROUP_SCHED */
561
562#ifdef CONFIG_SMP
563/*
564 * We ran out of runtime, see if we can borrow some from our neighbours.
565 */
566static int do_balance_runtime(struct rt_rq *rt_rq)
567{
568 struct rt_bandwidth *rt_b = sched_rt_bandwidth(rt_rq);
569 struct root_domain *rd = cpu_rq(smp_processor_id())->rd;
570 int i, weight, more = 0;
571 u64 rt_period;
572
573 weight = cpumask_weight(rd->span);
574
575 raw_spin_lock(&rt_b->rt_runtime_lock);
576 rt_period = ktime_to_ns(rt_b->rt_period);
577 for_each_cpu(i, rd->span) {
578 struct rt_rq *iter = sched_rt_period_rt_rq(rt_b, i);
579 s64 diff;
580
581 if (iter == rt_rq)
582 continue;
583
584 raw_spin_lock(&iter->rt_runtime_lock);
585 /*
586 * Either all rqs have inf runtime and there's nothing to steal
587 * or __disable_runtime() below sets a specific rq to inf to
588 * indicate its been disabled and disalow stealing.
589 */
590 if (iter->rt_runtime == RUNTIME_INF)
591 goto next;
592
593 /*
594 * From runqueues with spare time, take 1/n part of their
595 * spare time, but no more than our period.
596 */
597 diff = iter->rt_runtime - iter->rt_time;
598 if (diff > 0) {
599 diff = div_u64((u64)diff, weight);
600 if (rt_rq->rt_runtime + diff > rt_period)
601 diff = rt_period - rt_rq->rt_runtime;
602 iter->rt_runtime -= diff;
603 rt_rq->rt_runtime += diff;
604 more = 1;
605 if (rt_rq->rt_runtime == rt_period) {
606 raw_spin_unlock(&iter->rt_runtime_lock);
607 break;
608 }
609 }
610next:
611 raw_spin_unlock(&iter->rt_runtime_lock);
612 }
613 raw_spin_unlock(&rt_b->rt_runtime_lock);
614
615 return more;
616}
617
618/*
619 * Ensure this RQ takes back all the runtime it lend to its neighbours.
620 */
621static void __disable_runtime(struct rq *rq)
622{
623 struct root_domain *rd = rq->rd;
624 rt_rq_iter_t iter;
625 struct rt_rq *rt_rq;
626
627 if (unlikely(!scheduler_running))
628 return;
629
630 for_each_rt_rq(rt_rq, iter, rq) {
631 struct rt_bandwidth *rt_b = sched_rt_bandwidth(rt_rq);
632 s64 want;
633 int i;
634
635 raw_spin_lock(&rt_b->rt_runtime_lock);
636 raw_spin_lock(&rt_rq->rt_runtime_lock);
637 /*
638 * Either we're all inf and nobody needs to borrow, or we're
639 * already disabled and thus have nothing to do, or we have
640 * exactly the right amount of runtime to take out.
641 */
642 if (rt_rq->rt_runtime == RUNTIME_INF ||
643 rt_rq->rt_runtime == rt_b->rt_runtime)
644 goto balanced;
645 raw_spin_unlock(&rt_rq->rt_runtime_lock);
646
647 /*
648 * Calculate the difference between what we started out with
649 * and what we current have, that's the amount of runtime
650 * we lend and now have to reclaim.
651 */
652 want = rt_b->rt_runtime - rt_rq->rt_runtime;
653
654 /*
655 * Greedy reclaim, take back as much as we can.
656 */
657 for_each_cpu(i, rd->span) {
658 struct rt_rq *iter = sched_rt_period_rt_rq(rt_b, i);
659 s64 diff;
660
661 /*
662 * Can't reclaim from ourselves or disabled runqueues.
663 */
664 if (iter == rt_rq || iter->rt_runtime == RUNTIME_INF)
665 continue;
666
667 raw_spin_lock(&iter->rt_runtime_lock);
668 if (want > 0) {
669 diff = min_t(s64, iter->rt_runtime, want);
670 iter->rt_runtime -= diff;
671 want -= diff;
672 } else {
673 iter->rt_runtime -= want;
674 want -= want;
675 }
676 raw_spin_unlock(&iter->rt_runtime_lock);
677
678 if (!want)
679 break;
680 }
681
682 raw_spin_lock(&rt_rq->rt_runtime_lock);
683 /*
684 * We cannot be left wanting - that would mean some runtime
685 * leaked out of the system.
686 */
687 BUG_ON(want);
688balanced:
689 /*
690 * Disable all the borrow logic by pretending we have inf
691 * runtime - in which case borrowing doesn't make sense.
692 */
693 rt_rq->rt_runtime = RUNTIME_INF;
694 raw_spin_unlock(&rt_rq->rt_runtime_lock);
695 raw_spin_unlock(&rt_b->rt_runtime_lock);
696 }
697}
698
699static void disable_runtime(struct rq *rq)
700{
701 unsigned long flags;
702
703 raw_spin_lock_irqsave(&rq->lock, flags);
704 __disable_runtime(rq);
705 raw_spin_unlock_irqrestore(&rq->lock, flags);
706}
707
708static void __enable_runtime(struct rq *rq)
709{
710 rt_rq_iter_t iter;
711 struct rt_rq *rt_rq;
712
713 if (unlikely(!scheduler_running))
714 return;
715
716 /*
717 * Reset each runqueue's bandwidth settings
718 */
719 for_each_rt_rq(rt_rq, iter, rq) {
720 struct rt_bandwidth *rt_b = sched_rt_bandwidth(rt_rq);
721
722 raw_spin_lock(&rt_b->rt_runtime_lock);
723 raw_spin_lock(&rt_rq->rt_runtime_lock);
724 rt_rq->rt_runtime = rt_b->rt_runtime;
725 rt_rq->rt_time = 0;
726 rt_rq->rt_throttled = 0;
727 raw_spin_unlock(&rt_rq->rt_runtime_lock);
728 raw_spin_unlock(&rt_b->rt_runtime_lock);
729 }
730}
731
732static void enable_runtime(struct rq *rq)
733{
734 unsigned long flags;
735
736 raw_spin_lock_irqsave(&rq->lock, flags);
737 __enable_runtime(rq);
738 raw_spin_unlock_irqrestore(&rq->lock, flags);
739}
740
741int update_runtime(struct notifier_block *nfb, unsigned long action, void *hcpu)
742{
743 int cpu = (int)(long)hcpu;
744
745 switch (action) {
746 case CPU_DOWN_PREPARE:
747 case CPU_DOWN_PREPARE_FROZEN:
748 disable_runtime(cpu_rq(cpu));
749 return NOTIFY_OK;
750
751 case CPU_DOWN_FAILED:
752 case CPU_DOWN_FAILED_FROZEN:
753 case CPU_ONLINE:
754 case CPU_ONLINE_FROZEN:
755 enable_runtime(cpu_rq(cpu));
756 return NOTIFY_OK;
757
758 default:
759 return NOTIFY_DONE;
760 }
761}
762
763static int balance_runtime(struct rt_rq *rt_rq)
764{
765 int more = 0;
766
767 if (!sched_feat(RT_RUNTIME_SHARE))
768 return more;
769
770 if (rt_rq->rt_time > rt_rq->rt_runtime) {
771 raw_spin_unlock(&rt_rq->rt_runtime_lock);
772 more = do_balance_runtime(rt_rq);
773 raw_spin_lock(&rt_rq->rt_runtime_lock);
774 }
775
776 return more;
777}
778#else /* !CONFIG_SMP */
779static inline int balance_runtime(struct rt_rq *rt_rq)
780{
781 return 0;
782}
783#endif /* CONFIG_SMP */
784
785static int do_sched_rt_period_timer(struct rt_bandwidth *rt_b, int overrun)
786{
787 int i, idle = 1, throttled = 0;
788 const struct cpumask *span;
789
790 span = sched_rt_period_mask();
791 for_each_cpu(i, span) {
792 int enqueue = 0;
793 struct rt_rq *rt_rq = sched_rt_period_rt_rq(rt_b, i);
794 struct rq *rq = rq_of_rt_rq(rt_rq);
795
796 raw_spin_lock(&rq->lock);
797 if (rt_rq->rt_time) {
798 u64 runtime;
799
800 raw_spin_lock(&rt_rq->rt_runtime_lock);
801 if (rt_rq->rt_throttled)
802 balance_runtime(rt_rq);
803 runtime = rt_rq->rt_runtime;
804 rt_rq->rt_time -= min(rt_rq->rt_time, overrun*runtime);
805 if (rt_rq->rt_throttled && rt_rq->rt_time < runtime) {
806 rt_rq->rt_throttled = 0;
807 enqueue = 1;
808
809 /*
810 * Force a clock update if the CPU was idle,
811 * lest wakeup -> unthrottle time accumulate.
812 */
813 if (rt_rq->rt_nr_running && rq->curr == rq->idle)
814 rq->skip_clock_update = -1;
815 }
816 if (rt_rq->rt_time || rt_rq->rt_nr_running)
817 idle = 0;
818 raw_spin_unlock(&rt_rq->rt_runtime_lock);
819 } else if (rt_rq->rt_nr_running) {
820 idle = 0;
821 if (!rt_rq_throttled(rt_rq))
822 enqueue = 1;
823 }
824 if (rt_rq->rt_throttled)
825 throttled = 1;
826
827 if (enqueue)
828 sched_rt_rq_enqueue(rt_rq);
829 raw_spin_unlock(&rq->lock);
830 }
831
832 if (!throttled && (!rt_bandwidth_enabled() || rt_b->rt_runtime == RUNTIME_INF))
833 return 1;
834
835 return idle;
836}
837
838static inline int rt_se_prio(struct sched_rt_entity *rt_se)
839{
840#ifdef CONFIG_RT_GROUP_SCHED
841 struct rt_rq *rt_rq = group_rt_rq(rt_se);
842
843 if (rt_rq)
844 return rt_rq->highest_prio.curr;
845#endif
846
847 return rt_task_of(rt_se)->prio;
848}
849
850static int sched_rt_runtime_exceeded(struct rt_rq *rt_rq)
851{
852 u64 runtime = sched_rt_runtime(rt_rq);
853
854 if (rt_rq->rt_throttled)
855 return rt_rq_throttled(rt_rq);
856
857 if (runtime >= sched_rt_period(rt_rq))
858 return 0;
859
860 balance_runtime(rt_rq);
861 runtime = sched_rt_runtime(rt_rq);
862 if (runtime == RUNTIME_INF)
863 return 0;
864
865 if (rt_rq->rt_time > runtime) {
866 struct rt_bandwidth *rt_b = sched_rt_bandwidth(rt_rq);
867
868 /*
869 * Don't actually throttle groups that have no runtime assigned
870 * but accrue some time due to boosting.
871 */
872 if (likely(rt_b->rt_runtime)) {
873 static bool once = false;
874
875 rt_rq->rt_throttled = 1;
876
877 if (!once) {
878 once = true;
879 printk_sched("sched: RT throttling activated\n");
880 }
881 } else {
882 /*
883 * In case we did anyway, make it go away,
884 * replenishment is a joke, since it will replenish us
885 * with exactly 0 ns.
886 */
887 rt_rq->rt_time = 0;
888 }
889
890 if (rt_rq_throttled(rt_rq)) {
891 sched_rt_rq_dequeue(rt_rq);
892 return 1;
893 }
894 }
895
896 return 0;
897}
898
899/*
900 * Update the current task's runtime statistics. Skip current tasks that
901 * are not in our scheduling class.
902 */
903static void update_curr_rt(struct rq *rq)
904{
905 struct task_struct *curr = rq->curr;
906 struct sched_rt_entity *rt_se = &curr->rt;
907 struct rt_rq *rt_rq = rt_rq_of_se(rt_se);
908 u64 delta_exec;
909
910 if (curr->sched_class != &rt_sched_class)
911 return;
912
913 delta_exec = rq->clock_task - curr->se.exec_start;
914 if (unlikely((s64)delta_exec < 0))
915 delta_exec = 0;
916
917 schedstat_set(curr->se.statistics.exec_max,
918 max(curr->se.statistics.exec_max, delta_exec));
919
920 curr->se.sum_exec_runtime += delta_exec;
921 account_group_exec_runtime(curr, delta_exec);
922
923 curr->se.exec_start = rq->clock_task;
924 cpuacct_charge(curr, delta_exec);
925
926 sched_rt_avg_update(rq, delta_exec);
927
928 if (!rt_bandwidth_enabled())
929 return;
930
931 for_each_sched_rt_entity(rt_se) {
932 rt_rq = rt_rq_of_se(rt_se);
933
934 if (sched_rt_runtime(rt_rq) != RUNTIME_INF) {
935 raw_spin_lock(&rt_rq->rt_runtime_lock);
936 rt_rq->rt_time += delta_exec;
937 if (sched_rt_runtime_exceeded(rt_rq))
938 resched_task(curr);
939 raw_spin_unlock(&rt_rq->rt_runtime_lock);
940 }
941 }
942}
943
944#if defined CONFIG_SMP
945
946static void
947inc_rt_prio_smp(struct rt_rq *rt_rq, int prio, int prev_prio)
948{
949 struct rq *rq = rq_of_rt_rq(rt_rq);
950
951 if (rq->online && prio < prev_prio)
952 cpupri_set(&rq->rd->cpupri, rq->cpu, prio);
953}
954
955static void
956dec_rt_prio_smp(struct rt_rq *rt_rq, int prio, int prev_prio)
957{
958 struct rq *rq = rq_of_rt_rq(rt_rq);
959
960 if (rq->online && rt_rq->highest_prio.curr != prev_prio)
961 cpupri_set(&rq->rd->cpupri, rq->cpu, rt_rq->highest_prio.curr);
962}
963
964#else /* CONFIG_SMP */
965
966static inline
967void inc_rt_prio_smp(struct rt_rq *rt_rq, int prio, int prev_prio) {}
968static inline
969void dec_rt_prio_smp(struct rt_rq *rt_rq, int prio, int prev_prio) {}
970
971#endif /* CONFIG_SMP */
972
973#if defined CONFIG_SMP || defined CONFIG_RT_GROUP_SCHED
974static void
975inc_rt_prio(struct rt_rq *rt_rq, int prio)
976{
977 int prev_prio = rt_rq->highest_prio.curr;
978
979 if (prio < prev_prio)
980 rt_rq->highest_prio.curr = prio;
981
982 inc_rt_prio_smp(rt_rq, prio, prev_prio);
983}
984
985static void
986dec_rt_prio(struct rt_rq *rt_rq, int prio)
987{
988 int prev_prio = rt_rq->highest_prio.curr;
989
990 if (rt_rq->rt_nr_running) {
991
992 WARN_ON(prio < prev_prio);
993
994 /*
995 * This may have been our highest task, and therefore
996 * we may have some recomputation to do
997 */
998 if (prio == prev_prio) {
999 struct rt_prio_array *array = &rt_rq->active;
1000
1001 rt_rq->highest_prio.curr =
1002 sched_find_first_bit(array->bitmap);
1003 }
1004
1005 } else
1006 rt_rq->highest_prio.curr = MAX_RT_PRIO;
1007
1008 dec_rt_prio_smp(rt_rq, prio, prev_prio);
1009}
1010
1011#else
1012
1013static inline void inc_rt_prio(struct rt_rq *rt_rq, int prio) {}
1014static inline void dec_rt_prio(struct rt_rq *rt_rq, int prio) {}
1015
1016#endif /* CONFIG_SMP || CONFIG_RT_GROUP_SCHED */
1017
1018#ifdef CONFIG_RT_GROUP_SCHED
1019
1020static void
1021inc_rt_group(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
1022{
1023 if (rt_se_boosted(rt_se))
1024 rt_rq->rt_nr_boosted++;
1025
1026 if (rt_rq->tg)
1027 start_rt_bandwidth(&rt_rq->tg->rt_bandwidth);
1028}
1029
1030static void
1031dec_rt_group(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
1032{
1033 if (rt_se_boosted(rt_se))
1034 rt_rq->rt_nr_boosted--;
1035
1036 WARN_ON(!rt_rq->rt_nr_running && rt_rq->rt_nr_boosted);
1037}
1038
1039#else /* CONFIG_RT_GROUP_SCHED */
1040
1041static void
1042inc_rt_group(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
1043{
1044 start_rt_bandwidth(&def_rt_bandwidth);
1045}
1046
1047static inline
1048void dec_rt_group(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq) {}
1049
1050#endif /* CONFIG_RT_GROUP_SCHED */
1051
1052static inline
1053void inc_rt_tasks(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
1054{
1055 int prio = rt_se_prio(rt_se);
1056
1057 WARN_ON(!rt_prio(prio));
1058 rt_rq->rt_nr_running++;
1059
1060 inc_rt_prio(rt_rq, prio);
1061 inc_rt_migration(rt_se, rt_rq);
1062 inc_rt_group(rt_se, rt_rq);
1063}
1064
1065static inline
1066void dec_rt_tasks(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
1067{
1068 WARN_ON(!rt_prio(rt_se_prio(rt_se)));
1069 WARN_ON(!rt_rq->rt_nr_running);
1070 rt_rq->rt_nr_running--;
1071
1072 dec_rt_prio(rt_rq, rt_se_prio(rt_se));
1073 dec_rt_migration(rt_se, rt_rq);
1074 dec_rt_group(rt_se, rt_rq);
1075}
1076
1077static void __enqueue_rt_entity(struct sched_rt_entity *rt_se, bool head)
1078{
1079 struct rt_rq *rt_rq = rt_rq_of_se(rt_se);
1080 struct rt_prio_array *array = &rt_rq->active;
1081 struct rt_rq *group_rq = group_rt_rq(rt_se);
1082 struct list_head *queue = array->queue + rt_se_prio(rt_se);
1083
1084 /*
1085 * Don't enqueue the group if its throttled, or when empty.
1086 * The latter is a consequence of the former when a child group
1087 * get throttled and the current group doesn't have any other
1088 * active members.
1089 */
1090 if (group_rq && (rt_rq_throttled(group_rq) || !group_rq->rt_nr_running))
1091 return;
1092
1093 if (!rt_rq->rt_nr_running)
1094 list_add_leaf_rt_rq(rt_rq);
1095
1096 if (head)
1097 list_add(&rt_se->run_list, queue);
1098 else
1099 list_add_tail(&rt_se->run_list, queue);
1100 __set_bit(rt_se_prio(rt_se), array->bitmap);
1101
1102 inc_rt_tasks(rt_se, rt_rq);
1103}
1104
1105static void __dequeue_rt_entity(struct sched_rt_entity *rt_se)
1106{
1107 struct rt_rq *rt_rq = rt_rq_of_se(rt_se);
1108 struct rt_prio_array *array = &rt_rq->active;
1109
1110 list_del_init(&rt_se->run_list);
1111 if (list_empty(array->queue + rt_se_prio(rt_se)))
1112 __clear_bit(rt_se_prio(rt_se), array->bitmap);
1113
1114 dec_rt_tasks(rt_se, rt_rq);
1115 if (!rt_rq->rt_nr_running)
1116 list_del_leaf_rt_rq(rt_rq);
1117}
1118
1119/*
1120 * Because the prio of an upper entry depends on the lower
1121 * entries, we must remove entries top - down.
1122 */
1123static void dequeue_rt_stack(struct sched_rt_entity *rt_se)
1124{
1125 struct sched_rt_entity *back = NULL;
1126
1127 for_each_sched_rt_entity(rt_se) {
1128 rt_se->back = back;
1129 back = rt_se;
1130 }
1131
1132 for (rt_se = back; rt_se; rt_se = rt_se->back) {
1133 if (on_rt_rq(rt_se))
1134 __dequeue_rt_entity(rt_se);
1135 }
1136}
1137
1138static void enqueue_rt_entity(struct sched_rt_entity *rt_se, bool head)
1139{
1140 dequeue_rt_stack(rt_se);
1141 for_each_sched_rt_entity(rt_se)
1142 __enqueue_rt_entity(rt_se, head);
1143}
1144
1145static void dequeue_rt_entity(struct sched_rt_entity *rt_se)
1146{
1147 dequeue_rt_stack(rt_se);
1148
1149 for_each_sched_rt_entity(rt_se) {
1150 struct rt_rq *rt_rq = group_rt_rq(rt_se);
1151
1152 if (rt_rq && rt_rq->rt_nr_running)
1153 __enqueue_rt_entity(rt_se, false);
1154 }
1155}
1156
1157/*
1158 * Adding/removing a task to/from a priority array:
1159 */
1160static void
1161enqueue_task_rt(struct rq *rq, struct task_struct *p, int flags)
1162{
1163 struct sched_rt_entity *rt_se = &p->rt;
1164
1165 if (flags & ENQUEUE_WAKEUP)
1166 rt_se->timeout = 0;
1167
1168 enqueue_rt_entity(rt_se, flags & ENQUEUE_HEAD);
1169
1170 if (!task_current(rq, p) && p->nr_cpus_allowed > 1)
1171 enqueue_pushable_task(rq, p);
1172
1173 inc_nr_running(rq);
1174}
1175
1176static void dequeue_task_rt(struct rq *rq, struct task_struct *p, int flags)
1177{
1178 struct sched_rt_entity *rt_se = &p->rt;
1179
1180 update_curr_rt(rq);
1181 dequeue_rt_entity(rt_se);
1182
1183 dequeue_pushable_task(rq, p);
1184
1185 dec_nr_running(rq);
1186}
1187
1188/*
1189 * Put task to the head or the end of the run list without the overhead of
1190 * dequeue followed by enqueue.
1191 */
1192static void
1193requeue_rt_entity(struct rt_rq *rt_rq, struct sched_rt_entity *rt_se, int head)
1194{
1195 if (on_rt_rq(rt_se)) {
1196 struct rt_prio_array *array = &rt_rq->active;
1197 struct list_head *queue = array->queue + rt_se_prio(rt_se);
1198
1199 if (head)
1200 list_move(&rt_se->run_list, queue);
1201 else
1202 list_move_tail(&rt_se->run_list, queue);
1203 }
1204}
1205
1206static void requeue_task_rt(struct rq *rq, struct task_struct *p, int head)
1207{
1208 struct sched_rt_entity *rt_se = &p->rt;
1209 struct rt_rq *rt_rq;
1210
1211 for_each_sched_rt_entity(rt_se) {
1212 rt_rq = rt_rq_of_se(rt_se);
1213 requeue_rt_entity(rt_rq, rt_se, head);
1214 }
1215}
1216
1217static void yield_task_rt(struct rq *rq)
1218{
1219 requeue_task_rt(rq, rq->curr, 0);
1220}
1221
1222#ifdef CONFIG_SMP
1223static int find_lowest_rq(struct task_struct *task);
1224
1225static int
1226select_task_rq_rt(struct task_struct *p, int sd_flag, int flags)
1227{
1228 struct task_struct *curr;
1229 struct rq *rq;
1230 int cpu;
1231
1232 cpu = task_cpu(p);
1233
1234 if (p->nr_cpus_allowed == 1)
1235 goto out;
1236
1237 /* For anything but wake ups, just return the task_cpu */
1238 if (sd_flag != SD_BALANCE_WAKE && sd_flag != SD_BALANCE_FORK)
1239 goto out;
1240
1241 rq = cpu_rq(cpu);
1242
1243 rcu_read_lock();
1244 curr = ACCESS_ONCE(rq->curr); /* unlocked access */
1245
1246 /*
1247 * If the current task on @p's runqueue is an RT task, then
1248 * try to see if we can wake this RT task up on another
1249 * runqueue. Otherwise simply start this RT task
1250 * on its current runqueue.
1251 *
1252 * We want to avoid overloading runqueues. If the woken
1253 * task is a higher priority, then it will stay on this CPU
1254 * and the lower prio task should be moved to another CPU.
1255 * Even though this will probably make the lower prio task
1256 * lose its cache, we do not want to bounce a higher task
1257 * around just because it gave up its CPU, perhaps for a
1258 * lock?
1259 *
1260 * For equal prio tasks, we just let the scheduler sort it out.
1261 *
1262 * Otherwise, just let it ride on the affined RQ and the
1263 * post-schedule router will push the preempted task away
1264 *
1265 * This test is optimistic, if we get it wrong the load-balancer
1266 * will have to sort it out.
1267 */
1268 if (curr && unlikely(rt_task(curr)) &&
1269 (curr->nr_cpus_allowed < 2 ||
1270 curr->prio <= p->prio) &&
1271 (p->nr_cpus_allowed > 1)) {
1272 int target = find_lowest_rq(p);
1273
1274 if (target != -1)
1275 cpu = target;
1276 }
1277 rcu_read_unlock();
1278
1279out:
1280 return cpu;
1281}
1282
1283static void check_preempt_equal_prio(struct rq *rq, struct task_struct *p)
1284{
1285 if (rq->curr->nr_cpus_allowed == 1)
1286 return;
1287
1288 if (p->nr_cpus_allowed != 1
1289 && cpupri_find(&rq->rd->cpupri, p, NULL))
1290 return;
1291
1292 if (!cpupri_find(&rq->rd->cpupri, rq->curr, NULL))
1293 return;
1294
1295 /*
1296 * There appears to be other cpus that can accept
1297 * current and none to run 'p', so lets reschedule
1298 * to try and push current away:
1299 */
1300 requeue_task_rt(rq, p, 1);
1301 resched_task(rq->curr);
1302}
1303
1304#endif /* CONFIG_SMP */
1305
1306/*
1307 * Preempt the current task with a newly woken task if needed:
1308 */
1309static void check_preempt_curr_rt(struct rq *rq, struct task_struct *p, int flags)
1310{
1311 if (p->prio < rq->curr->prio) {
1312 resched_task(rq->curr);
1313 return;
1314 }
1315
1316#ifdef CONFIG_SMP
1317 /*
1318 * If:
1319 *
1320 * - the newly woken task is of equal priority to the current task
1321 * - the newly woken task is non-migratable while current is migratable
1322 * - current will be preempted on the next reschedule
1323 *
1324 * we should check to see if current can readily move to a different
1325 * cpu. If so, we will reschedule to allow the push logic to try
1326 * to move current somewhere else, making room for our non-migratable
1327 * task.
1328 */
1329 if (p->prio == rq->curr->prio && !test_tsk_need_resched(rq->curr))
1330 check_preempt_equal_prio(rq, p);
1331#endif
1332}
1333
1334static struct sched_rt_entity *pick_next_rt_entity(struct rq *rq,
1335 struct rt_rq *rt_rq)
1336{
1337 struct rt_prio_array *array = &rt_rq->active;
1338 struct sched_rt_entity *next = NULL;
1339 struct list_head *queue;
1340 int idx;
1341
1342 idx = sched_find_first_bit(array->bitmap);
1343 BUG_ON(idx >= MAX_RT_PRIO);
1344
1345 queue = array->queue + idx;
1346 next = list_entry(queue->next, struct sched_rt_entity, run_list);
1347
1348 return next;
1349}
1350
1351static struct task_struct *_pick_next_task_rt(struct rq *rq)
1352{
1353 struct sched_rt_entity *rt_se;
1354 struct task_struct *p;
1355 struct rt_rq *rt_rq;
1356
1357 rt_rq = &rq->rt;
1358
1359 if (!rt_rq->rt_nr_running)
1360 return NULL;
1361
1362 if (rt_rq_throttled(rt_rq))
1363 return NULL;
1364
1365 do {
1366 rt_se = pick_next_rt_entity(rq, rt_rq);
1367 BUG_ON(!rt_se);
1368 rt_rq = group_rt_rq(rt_se);
1369 } while (rt_rq);
1370
1371 p = rt_task_of(rt_se);
1372 p->se.exec_start = rq->clock_task;
1373
1374 return p;
1375}
1376
1377static struct task_struct *pick_next_task_rt(struct rq *rq)
1378{
1379 struct task_struct *p = _pick_next_task_rt(rq);
1380
1381 /* The running task is never eligible for pushing */
1382 if (p)
1383 dequeue_pushable_task(rq, p);
1384
1385#ifdef CONFIG_SMP
1386 /*
1387 * We detect this state here so that we can avoid taking the RQ
1388 * lock again later if there is no need to push
1389 */
1390 rq->post_schedule = has_pushable_tasks(rq);
1391#endif
1392
1393 return p;
1394}
1395
1396static void put_prev_task_rt(struct rq *rq, struct task_struct *p)
1397{
1398 update_curr_rt(rq);
1399
1400 /*
1401 * The previous task needs to be made eligible for pushing
1402 * if it is still active
1403 */
1404 if (on_rt_rq(&p->rt) && p->nr_cpus_allowed > 1)
1405 enqueue_pushable_task(rq, p);
1406}
1407
1408#ifdef CONFIG_SMP
1409
1410/* Only try algorithms three times */
1411#define RT_MAX_TRIES 3
1412
1413static int pick_rt_task(struct rq *rq, struct task_struct *p, int cpu)
1414{
1415 if (!task_running(rq, p) &&
1416 (cpu < 0 || cpumask_test_cpu(cpu, tsk_cpus_allowed(p))) &&
1417 (p->nr_cpus_allowed > 1))
1418 return 1;
1419 return 0;
1420}
1421
1422/* Return the second highest RT task, NULL otherwise */
1423static struct task_struct *pick_next_highest_task_rt(struct rq *rq, int cpu)
1424{
1425 struct task_struct *next = NULL;
1426 struct sched_rt_entity *rt_se;
1427 struct rt_prio_array *array;
1428 struct rt_rq *rt_rq;
1429 int idx;
1430
1431 for_each_leaf_rt_rq(rt_rq, rq) {
1432 array = &rt_rq->active;
1433 idx = sched_find_first_bit(array->bitmap);
1434next_idx:
1435 if (idx >= MAX_RT_PRIO)
1436 continue;
1437 if (next && next->prio <= idx)
1438 continue;
1439 list_for_each_entry(rt_se, array->queue + idx, run_list) {
1440 struct task_struct *p;
1441
1442 if (!rt_entity_is_task(rt_se))
1443 continue;
1444
1445 p = rt_task_of(rt_se);
1446 if (pick_rt_task(rq, p, cpu)) {
1447 next = p;
1448 break;
1449 }
1450 }
1451 if (!next) {
1452 idx = find_next_bit(array->bitmap, MAX_RT_PRIO, idx+1);
1453 goto next_idx;
1454 }
1455 }
1456
1457 return next;
1458}
1459
1460static DEFINE_PER_CPU(cpumask_var_t, local_cpu_mask);
1461
1462static int find_lowest_rq(struct task_struct *task)
1463{
1464 struct sched_domain *sd;
1465 struct cpumask *lowest_mask = __get_cpu_var(local_cpu_mask);
1466 int this_cpu = smp_processor_id();
1467 int cpu = task_cpu(task);
1468
1469 /* Make sure the mask is initialized first */
1470 if (unlikely(!lowest_mask))
1471 return -1;
1472
1473 if (task->nr_cpus_allowed == 1)
1474 return -1; /* No other targets possible */
1475
1476 if (!cpupri_find(&task_rq(task)->rd->cpupri, task, lowest_mask))
1477 return -1; /* No targets found */
1478
1479 /*
1480 * At this point we have built a mask of cpus representing the
1481 * lowest priority tasks in the system. Now we want to elect
1482 * the best one based on our affinity and topology.
1483 *
1484 * We prioritize the last cpu that the task executed on since
1485 * it is most likely cache-hot in that location.
1486 */
1487 if (cpumask_test_cpu(cpu, lowest_mask))
1488 return cpu;
1489
1490 /*
1491 * Otherwise, we consult the sched_domains span maps to figure
1492 * out which cpu is logically closest to our hot cache data.
1493 */
1494 if (!cpumask_test_cpu(this_cpu, lowest_mask))
1495 this_cpu = -1; /* Skip this_cpu opt if not among lowest */
1496
1497 rcu_read_lock();
1498 for_each_domain(cpu, sd) {
1499 if (sd->flags & SD_WAKE_AFFINE) {
1500 int best_cpu;
1501
1502 /*
1503 * "this_cpu" is cheaper to preempt than a
1504 * remote processor.
1505 */
1506 if (this_cpu != -1 &&
1507 cpumask_test_cpu(this_cpu, sched_domain_span(sd))) {
1508 rcu_read_unlock();
1509 return this_cpu;
1510 }
1511
1512 best_cpu = cpumask_first_and(lowest_mask,
1513 sched_domain_span(sd));
1514 if (best_cpu < nr_cpu_ids) {
1515 rcu_read_unlock();
1516 return best_cpu;
1517 }
1518 }
1519 }
1520 rcu_read_unlock();
1521
1522 /*
1523 * And finally, if there were no matches within the domains
1524 * just give the caller *something* to work with from the compatible
1525 * locations.
1526 */
1527 if (this_cpu != -1)
1528 return this_cpu;
1529
1530 cpu = cpumask_any(lowest_mask);
1531 if (cpu < nr_cpu_ids)
1532 return cpu;
1533 return -1;
1534}
1535
1536/* Will lock the rq it finds */
1537static struct rq *find_lock_lowest_rq(struct task_struct *task, struct rq *rq)
1538{
1539 struct rq *lowest_rq = NULL;
1540 int tries;
1541 int cpu;
1542
1543 for (tries = 0; tries < RT_MAX_TRIES; tries++) {
1544 cpu = find_lowest_rq(task);
1545
1546 if ((cpu == -1) || (cpu == rq->cpu))
1547 break;
1548
1549 lowest_rq = cpu_rq(cpu);
1550
1551 /* if the prio of this runqueue changed, try again */
1552 if (double_lock_balance(rq, lowest_rq)) {
1553 /*
1554 * We had to unlock the run queue. In
1555 * the mean time, task could have
1556 * migrated already or had its affinity changed.
1557 * Also make sure that it wasn't scheduled on its rq.
1558 */
1559 if (unlikely(task_rq(task) != rq ||
1560 !cpumask_test_cpu(lowest_rq->cpu,
1561 tsk_cpus_allowed(task)) ||
1562 task_running(rq, task) ||
1563 !task->on_rq)) {
1564
1565 double_unlock_balance(rq, lowest_rq);
1566 lowest_rq = NULL;
1567 break;
1568 }
1569 }
1570
1571 /* If this rq is still suitable use it. */
1572 if (lowest_rq->rt.highest_prio.curr > task->prio)
1573 break;
1574
1575 /* try again */
1576 double_unlock_balance(rq, lowest_rq);
1577 lowest_rq = NULL;
1578 }
1579
1580 return lowest_rq;
1581}
1582
1583static struct task_struct *pick_next_pushable_task(struct rq *rq)
1584{
1585 struct task_struct *p;
1586
1587 if (!has_pushable_tasks(rq))
1588 return NULL;
1589
1590 p = plist_first_entry(&rq->rt.pushable_tasks,
1591 struct task_struct, pushable_tasks);
1592
1593 BUG_ON(rq->cpu != task_cpu(p));
1594 BUG_ON(task_current(rq, p));
1595 BUG_ON(p->nr_cpus_allowed <= 1);
1596
1597 BUG_ON(!p->on_rq);
1598 BUG_ON(!rt_task(p));
1599
1600 return p;
1601}
1602
1603/*
1604 * If the current CPU has more than one RT task, see if the non
1605 * running task can migrate over to a CPU that is running a task
1606 * of lesser priority.
1607 */
1608static int push_rt_task(struct rq *rq)
1609{
1610 struct task_struct *next_task;
1611 struct rq *lowest_rq;
1612 int ret = 0;
1613
1614 if (!rq->rt.overloaded)
1615 return 0;
1616
1617 next_task = pick_next_pushable_task(rq);
1618 if (!next_task)
1619 return 0;
1620
1621#ifdef __ARCH_WANT_INTERRUPTS_ON_CTXSW
1622 if (unlikely(task_running(rq, next_task)))
1623 return 0;
1624#endif
1625
1626retry:
1627 if (unlikely(next_task == rq->curr)) {
1628 WARN_ON(1);
1629 return 0;
1630 }
1631
1632 /*
1633 * It's possible that the next_task slipped in of
1634 * higher priority than current. If that's the case
1635 * just reschedule current.
1636 */
1637 if (unlikely(next_task->prio < rq->curr->prio)) {
1638 resched_task(rq->curr);
1639 return 0;
1640 }
1641
1642 /* We might release rq lock */
1643 get_task_struct(next_task);
1644
1645 /* find_lock_lowest_rq locks the rq if found */
1646 lowest_rq = find_lock_lowest_rq(next_task, rq);
1647 if (!lowest_rq) {
1648 struct task_struct *task;
1649 /*
1650 * find_lock_lowest_rq releases rq->lock
1651 * so it is possible that next_task has migrated.
1652 *
1653 * We need to make sure that the task is still on the same
1654 * run-queue and is also still the next task eligible for
1655 * pushing.
1656 */
1657 task = pick_next_pushable_task(rq);
1658 if (task_cpu(next_task) == rq->cpu && task == next_task) {
1659 /*
1660 * The task hasn't migrated, and is still the next
1661 * eligible task, but we failed to find a run-queue
1662 * to push it to. Do not retry in this case, since
1663 * other cpus will pull from us when ready.
1664 */
1665 goto out;
1666 }
1667
1668 if (!task)
1669 /* No more tasks, just exit */
1670 goto out;
1671
1672 /*
1673 * Something has shifted, try again.
1674 */
1675 put_task_struct(next_task);
1676 next_task = task;
1677 goto retry;
1678 }
1679
1680 deactivate_task(rq, next_task, 0);
1681 set_task_cpu(next_task, lowest_rq->cpu);
1682 activate_task(lowest_rq, next_task, 0);
1683 ret = 1;
1684
1685 resched_task(lowest_rq->curr);
1686
1687 double_unlock_balance(rq, lowest_rq);
1688
1689out:
1690 put_task_struct(next_task);
1691
1692 return ret;
1693}
1694
1695static void push_rt_tasks(struct rq *rq)
1696{
1697 /* push_rt_task will return true if it moved an RT */
1698 while (push_rt_task(rq))
1699 ;
1700}
1701
1702static int pull_rt_task(struct rq *this_rq)
1703{
1704 int this_cpu = this_rq->cpu, ret = 0, cpu;
1705 struct task_struct *p;
1706 struct rq *src_rq;
1707
1708 if (likely(!rt_overloaded(this_rq)))
1709 return 0;
1710
1711 for_each_cpu(cpu, this_rq->rd->rto_mask) {
1712 if (this_cpu == cpu)
1713 continue;
1714
1715 src_rq = cpu_rq(cpu);
1716
1717 /*
1718 * Don't bother taking the src_rq->lock if the next highest
1719 * task is known to be lower-priority than our current task.
1720 * This may look racy, but if this value is about to go
1721 * logically higher, the src_rq will push this task away.
1722 * And if its going logically lower, we do not care
1723 */
1724 if (src_rq->rt.highest_prio.next >=
1725 this_rq->rt.highest_prio.curr)
1726 continue;
1727
1728 /*
1729 * We can potentially drop this_rq's lock in
1730 * double_lock_balance, and another CPU could
1731 * alter this_rq
1732 */
1733 double_lock_balance(this_rq, src_rq);
1734
1735 /*
1736 * Are there still pullable RT tasks?
1737 */
1738 if (src_rq->rt.rt_nr_running <= 1)
1739 goto skip;
1740
1741 p = pick_next_highest_task_rt(src_rq, this_cpu);
1742
1743 /*
1744 * Do we have an RT task that preempts
1745 * the to-be-scheduled task?
1746 */
1747 if (p && (p->prio < this_rq->rt.highest_prio.curr)) {
1748 WARN_ON(p == src_rq->curr);
1749 WARN_ON(!p->on_rq);
1750
1751 /*
1752 * There's a chance that p is higher in priority
1753 * than what's currently running on its cpu.
1754 * This is just that p is wakeing up and hasn't
1755 * had a chance to schedule. We only pull
1756 * p if it is lower in priority than the
1757 * current task on the run queue
1758 */
1759 if (p->prio < src_rq->curr->prio)
1760 goto skip;
1761
1762 ret = 1;
1763
1764 deactivate_task(src_rq, p, 0);
1765 set_task_cpu(p, this_cpu);
1766 activate_task(this_rq, p, 0);
1767 /*
1768 * We continue with the search, just in
1769 * case there's an even higher prio task
1770 * in another runqueue. (low likelihood
1771 * but possible)
1772 */
1773 }
1774skip:
1775 double_unlock_balance(this_rq, src_rq);
1776 }
1777
1778 return ret;
1779}
1780
1781static void pre_schedule_rt(struct rq *rq, struct task_struct *prev)
1782{
1783 /* Try to pull RT tasks here if we lower this rq's prio */
1784 if (rq->rt.highest_prio.curr > prev->prio)
1785 pull_rt_task(rq);
1786}
1787
1788static void post_schedule_rt(struct rq *rq)
1789{
1790 push_rt_tasks(rq);
1791}
1792
1793/*
1794 * If we are not running and we are not going to reschedule soon, we should
1795 * try to push tasks away now
1796 */
1797static void task_woken_rt(struct rq *rq, struct task_struct *p)
1798{
1799 if (!task_running(rq, p) &&
1800 !test_tsk_need_resched(rq->curr) &&
1801 has_pushable_tasks(rq) &&
1802 p->nr_cpus_allowed > 1 &&
1803 rt_task(rq->curr) &&
1804 (rq->curr->nr_cpus_allowed < 2 ||
1805 rq->curr->prio <= p->prio))
1806 push_rt_tasks(rq);
1807}
1808
1809static void set_cpus_allowed_rt(struct task_struct *p,
1810 const struct cpumask *new_mask)
1811{
1812 struct rq *rq;
1813 int weight;
1814
1815 BUG_ON(!rt_task(p));
1816
1817 if (!p->on_rq)
1818 return;
1819
1820 weight = cpumask_weight(new_mask);
1821
1822 /*
1823 * Only update if the process changes its state from whether it
1824 * can migrate or not.
1825 */
1826 if ((p->nr_cpus_allowed > 1) == (weight > 1))
1827 return;
1828
1829 rq = task_rq(p);
1830
1831 /*
1832 * The process used to be able to migrate OR it can now migrate
1833 */
1834 if (weight <= 1) {
1835 if (!task_current(rq, p))
1836 dequeue_pushable_task(rq, p);
1837 BUG_ON(!rq->rt.rt_nr_migratory);
1838 rq->rt.rt_nr_migratory--;
1839 } else {
1840 if (!task_current(rq, p))
1841 enqueue_pushable_task(rq, p);
1842 rq->rt.rt_nr_migratory++;
1843 }
1844
1845 update_rt_migration(&rq->rt);
1846}
1847
1848/* Assumes rq->lock is held */
1849static void rq_online_rt(struct rq *rq)
1850{
1851 if (rq->rt.overloaded)
1852 rt_set_overload(rq);
1853
1854 __enable_runtime(rq);
1855
1856 cpupri_set(&rq->rd->cpupri, rq->cpu, rq->rt.highest_prio.curr);
1857}
1858
1859/* Assumes rq->lock is held */
1860static void rq_offline_rt(struct rq *rq)
1861{
1862 if (rq->rt.overloaded)
1863 rt_clear_overload(rq);
1864
1865 __disable_runtime(rq);
1866
1867 cpupri_set(&rq->rd->cpupri, rq->cpu, CPUPRI_INVALID);
1868}
1869
1870/*
1871 * When switch from the rt queue, we bring ourselves to a position
1872 * that we might want to pull RT tasks from other runqueues.
1873 */
1874static void switched_from_rt(struct rq *rq, struct task_struct *p)
1875{
1876 /*
1877 * If there are other RT tasks then we will reschedule
1878 * and the scheduling of the other RT tasks will handle
1879 * the balancing. But if we are the last RT task
1880 * we may need to handle the pulling of RT tasks
1881 * now.
1882 */
1883 if (p->on_rq && !rq->rt.rt_nr_running)
1884 pull_rt_task(rq);
1885}
1886
1887void init_sched_rt_class(void)
1888{
1889 unsigned int i;
1890
1891 for_each_possible_cpu(i) {
1892 zalloc_cpumask_var_node(&per_cpu(local_cpu_mask, i),
1893 GFP_KERNEL, cpu_to_node(i));
1894 }
1895}
1896#endif /* CONFIG_SMP */
1897
1898/*
1899 * When switching a task to RT, we may overload the runqueue
1900 * with RT tasks. In this case we try to push them off to
1901 * other runqueues.
1902 */
1903static void switched_to_rt(struct rq *rq, struct task_struct *p)
1904{
1905 int check_resched = 1;
1906
1907 /*
1908 * If we are already running, then there's nothing
1909 * that needs to be done. But if we are not running
1910 * we may need to preempt the current running task.
1911 * If that current running task is also an RT task
1912 * then see if we can move to another run queue.
1913 */
1914 if (p->on_rq && rq->curr != p) {
1915#ifdef CONFIG_SMP
1916 if (rq->rt.overloaded && push_rt_task(rq) &&
1917 /* Don't resched if we changed runqueues */
1918 rq != task_rq(p))
1919 check_resched = 0;
1920#endif /* CONFIG_SMP */
1921 if (check_resched && p->prio < rq->curr->prio)
1922 resched_task(rq->curr);
1923 }
1924}
1925
1926/*
1927 * Priority of the task has changed. This may cause
1928 * us to initiate a push or pull.
1929 */
1930static void
1931prio_changed_rt(struct rq *rq, struct task_struct *p, int oldprio)
1932{
1933 if (!p->on_rq)
1934 return;
1935
1936 if (rq->curr == p) {
1937#ifdef CONFIG_SMP
1938 /*
1939 * If our priority decreases while running, we
1940 * may need to pull tasks to this runqueue.
1941 */
1942 if (oldprio < p->prio)
1943 pull_rt_task(rq);
1944 /*
1945 * If there's a higher priority task waiting to run
1946 * then reschedule. Note, the above pull_rt_task
1947 * can release the rq lock and p could migrate.
1948 * Only reschedule if p is still on the same runqueue.
1949 */
1950 if (p->prio > rq->rt.highest_prio.curr && rq->curr == p)
1951 resched_task(p);
1952#else
1953 /* For UP simply resched on drop of prio */
1954 if (oldprio < p->prio)
1955 resched_task(p);
1956#endif /* CONFIG_SMP */
1957 } else {
1958 /*
1959 * This task is not running, but if it is
1960 * greater than the current running task
1961 * then reschedule.
1962 */
1963 if (p->prio < rq->curr->prio)
1964 resched_task(rq->curr);
1965 }
1966}
1967
1968static void watchdog(struct rq *rq, struct task_struct *p)
1969{
1970 unsigned long soft, hard;
1971
1972 /* max may change after cur was read, this will be fixed next tick */
1973 soft = task_rlimit(p, RLIMIT_RTTIME);
1974 hard = task_rlimit_max(p, RLIMIT_RTTIME);
1975
1976 if (soft != RLIM_INFINITY) {
1977 unsigned long next;
1978
1979 p->rt.timeout++;
1980 next = DIV_ROUND_UP(min(soft, hard), USEC_PER_SEC/HZ);
1981 if (p->rt.timeout > next)
1982 p->cputime_expires.sched_exp = p->se.sum_exec_runtime;
1983 }
1984}
1985
1986static void task_tick_rt(struct rq *rq, struct task_struct *p, int queued)
1987{
1988 struct sched_rt_entity *rt_se = &p->rt;
1989
1990 update_curr_rt(rq);
1991
1992 watchdog(rq, p);
1993
1994 /*
1995 * RR tasks need a special form of timeslice management.
1996 * FIFO tasks have no timeslices.
1997 */
1998 if (p->policy != SCHED_RR)
1999 return;
2000
2001 if (--p->rt.time_slice)
2002 return;
2003
2004 p->rt.time_slice = RR_TIMESLICE;
2005
2006 /*
2007 * Requeue to the end of queue if we (and all of our ancestors) are the
2008 * only element on the queue
2009 */
2010 for_each_sched_rt_entity(rt_se) {
2011 if (rt_se->run_list.prev != rt_se->run_list.next) {
2012 requeue_task_rt(rq, p, 0);
2013 set_tsk_need_resched(p);
2014 return;
2015 }
2016 }
2017}
2018
2019static void set_curr_task_rt(struct rq *rq)
2020{
2021 struct task_struct *p = rq->curr;
2022
2023 p->se.exec_start = rq->clock_task;
2024
2025 /* The running task is never eligible for pushing */
2026 dequeue_pushable_task(rq, p);
2027}
2028
2029static unsigned int get_rr_interval_rt(struct rq *rq, struct task_struct *task)
2030{
2031 /*
2032 * Time slice is 0 for SCHED_FIFO tasks
2033 */
2034 if (task->policy == SCHED_RR)
2035 return RR_TIMESLICE;
2036 else
2037 return 0;
2038}
2039
2040const struct sched_class rt_sched_class = {
2041 .next = &fair_sched_class,
2042 .enqueue_task = enqueue_task_rt,
2043 .dequeue_task = dequeue_task_rt,
2044 .yield_task = yield_task_rt,
2045
2046 .check_preempt_curr = check_preempt_curr_rt,
2047
2048 .pick_next_task = pick_next_task_rt,
2049 .put_prev_task = put_prev_task_rt,
2050
2051#ifdef CONFIG_SMP
2052 .select_task_rq = select_task_rq_rt,
2053
2054 .set_cpus_allowed = set_cpus_allowed_rt,
2055 .rq_online = rq_online_rt,
2056 .rq_offline = rq_offline_rt,
2057 .pre_schedule = pre_schedule_rt,
2058 .post_schedule = post_schedule_rt,
2059 .task_woken = task_woken_rt,
2060 .switched_from = switched_from_rt,
2061#endif
2062
2063 .set_curr_task = set_curr_task_rt,
2064 .task_tick = task_tick_rt,
2065
2066 .get_rr_interval = get_rr_interval_rt,
2067
2068 .prio_changed = prio_changed_rt,
2069 .switched_to = switched_to_rt,
2070};
2071
2072#ifdef CONFIG_SCHED_DEBUG
2073extern void print_rt_rq(struct seq_file *m, int cpu, struct rt_rq *rt_rq);
2074
2075void print_rt_stats(struct seq_file *m, int cpu)
2076{
2077 rt_rq_iter_t iter;
2078 struct rt_rq *rt_rq;
2079
2080 rcu_read_lock();
2081 for_each_rt_rq(rt_rq, iter, cpu_rq(cpu))
2082 print_rt_rq(m, cpu, rt_rq);
2083 rcu_read_unlock();
2084}
2085#endif /* CONFIG_SCHED_DEBUG */