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