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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Real-Time Scheduling Class (mapped to the SCHED_FIFO and SCHED_RR
4 * policies)
5 */
6
7int sched_rr_timeslice = RR_TIMESLICE;
8/* More than 4 hours if BW_SHIFT equals 20. */
9static const u64 max_rt_runtime = MAX_BW;
10
11static int do_sched_rt_period_timer(struct rt_bandwidth *rt_b, int overrun);
12
13struct rt_bandwidth def_rt_bandwidth;
14
15/*
16 * period over which we measure -rt task CPU usage in us.
17 * default: 1s
18 */
19unsigned int sysctl_sched_rt_period = 1000000;
20
21/*
22 * part of the period that we allow rt tasks to run in us.
23 * default: 0.95s
24 */
25int sysctl_sched_rt_runtime = 950000;
26
27#ifdef CONFIG_SYSCTL
28static int sysctl_sched_rr_timeslice = (MSEC_PER_SEC / HZ) * RR_TIMESLICE;
29static int sched_rt_handler(struct ctl_table *table, int write, void *buffer,
30 size_t *lenp, loff_t *ppos);
31static int sched_rr_handler(struct ctl_table *table, int write, void *buffer,
32 size_t *lenp, loff_t *ppos);
33static struct ctl_table sched_rt_sysctls[] = {
34 {
35 .procname = "sched_rt_period_us",
36 .data = &sysctl_sched_rt_period,
37 .maxlen = sizeof(unsigned int),
38 .mode = 0644,
39 .proc_handler = sched_rt_handler,
40 },
41 {
42 .procname = "sched_rt_runtime_us",
43 .data = &sysctl_sched_rt_runtime,
44 .maxlen = sizeof(int),
45 .mode = 0644,
46 .proc_handler = sched_rt_handler,
47 },
48 {
49 .procname = "sched_rr_timeslice_ms",
50 .data = &sysctl_sched_rr_timeslice,
51 .maxlen = sizeof(int),
52 .mode = 0644,
53 .proc_handler = sched_rr_handler,
54 },
55 {}
56};
57
58static int __init sched_rt_sysctl_init(void)
59{
60 register_sysctl_init("kernel", sched_rt_sysctls);
61 return 0;
62}
63late_initcall(sched_rt_sysctl_init);
64#endif
65
66static enum hrtimer_restart sched_rt_period_timer(struct hrtimer *timer)
67{
68 struct rt_bandwidth *rt_b =
69 container_of(timer, struct rt_bandwidth, rt_period_timer);
70 int idle = 0;
71 int overrun;
72
73 raw_spin_lock(&rt_b->rt_runtime_lock);
74 for (;;) {
75 overrun = hrtimer_forward_now(timer, rt_b->rt_period);
76 if (!overrun)
77 break;
78
79 raw_spin_unlock(&rt_b->rt_runtime_lock);
80 idle = do_sched_rt_period_timer(rt_b, overrun);
81 raw_spin_lock(&rt_b->rt_runtime_lock);
82 }
83 if (idle)
84 rt_b->rt_period_active = 0;
85 raw_spin_unlock(&rt_b->rt_runtime_lock);
86
87 return idle ? HRTIMER_NORESTART : HRTIMER_RESTART;
88}
89
90void init_rt_bandwidth(struct rt_bandwidth *rt_b, u64 period, u64 runtime)
91{
92 rt_b->rt_period = ns_to_ktime(period);
93 rt_b->rt_runtime = runtime;
94
95 raw_spin_lock_init(&rt_b->rt_runtime_lock);
96
97 hrtimer_init(&rt_b->rt_period_timer, CLOCK_MONOTONIC,
98 HRTIMER_MODE_REL_HARD);
99 rt_b->rt_period_timer.function = sched_rt_period_timer;
100}
101
102static inline void do_start_rt_bandwidth(struct rt_bandwidth *rt_b)
103{
104 raw_spin_lock(&rt_b->rt_runtime_lock);
105 if (!rt_b->rt_period_active) {
106 rt_b->rt_period_active = 1;
107 /*
108 * SCHED_DEADLINE updates the bandwidth, as a run away
109 * RT task with a DL task could hog a CPU. But DL does
110 * not reset the period. If a deadline task was running
111 * without an RT task running, it can cause RT tasks to
112 * throttle when they start up. Kick the timer right away
113 * to update the period.
114 */
115 hrtimer_forward_now(&rt_b->rt_period_timer, ns_to_ktime(0));
116 hrtimer_start_expires(&rt_b->rt_period_timer,
117 HRTIMER_MODE_ABS_PINNED_HARD);
118 }
119 raw_spin_unlock(&rt_b->rt_runtime_lock);
120}
121
122static void start_rt_bandwidth(struct rt_bandwidth *rt_b)
123{
124 if (!rt_bandwidth_enabled() || rt_b->rt_runtime == RUNTIME_INF)
125 return;
126
127 do_start_rt_bandwidth(rt_b);
128}
129
130void init_rt_rq(struct rt_rq *rt_rq)
131{
132 struct rt_prio_array *array;
133 int i;
134
135 array = &rt_rq->active;
136 for (i = 0; i < MAX_RT_PRIO; i++) {
137 INIT_LIST_HEAD(array->queue + i);
138 __clear_bit(i, array->bitmap);
139 }
140 /* delimiter for bitsearch: */
141 __set_bit(MAX_RT_PRIO, array->bitmap);
142
143#if defined CONFIG_SMP
144 rt_rq->highest_prio.curr = MAX_RT_PRIO-1;
145 rt_rq->highest_prio.next = MAX_RT_PRIO-1;
146 rt_rq->rt_nr_migratory = 0;
147 rt_rq->overloaded = 0;
148 plist_head_init(&rt_rq->pushable_tasks);
149#endif /* CONFIG_SMP */
150 /* We start is dequeued state, because no RT tasks are queued */
151 rt_rq->rt_queued = 0;
152
153 rt_rq->rt_time = 0;
154 rt_rq->rt_throttled = 0;
155 rt_rq->rt_runtime = 0;
156 raw_spin_lock_init(&rt_rq->rt_runtime_lock);
157}
158
159#ifdef CONFIG_RT_GROUP_SCHED
160static void destroy_rt_bandwidth(struct rt_bandwidth *rt_b)
161{
162 hrtimer_cancel(&rt_b->rt_period_timer);
163}
164
165#define rt_entity_is_task(rt_se) (!(rt_se)->my_q)
166
167static inline struct task_struct *rt_task_of(struct sched_rt_entity *rt_se)
168{
169#ifdef CONFIG_SCHED_DEBUG
170 WARN_ON_ONCE(!rt_entity_is_task(rt_se));
171#endif
172 return container_of(rt_se, struct task_struct, rt);
173}
174
175static inline struct rq *rq_of_rt_rq(struct rt_rq *rt_rq)
176{
177 return rt_rq->rq;
178}
179
180static inline struct rt_rq *rt_rq_of_se(struct sched_rt_entity *rt_se)
181{
182 return rt_se->rt_rq;
183}
184
185static inline struct rq *rq_of_rt_se(struct sched_rt_entity *rt_se)
186{
187 struct rt_rq *rt_rq = rt_se->rt_rq;
188
189 return rt_rq->rq;
190}
191
192void unregister_rt_sched_group(struct task_group *tg)
193{
194 if (tg->rt_se)
195 destroy_rt_bandwidth(&tg->rt_bandwidth);
196
197}
198
199void free_rt_sched_group(struct task_group *tg)
200{
201 int i;
202
203 for_each_possible_cpu(i) {
204 if (tg->rt_rq)
205 kfree(tg->rt_rq[i]);
206 if (tg->rt_se)
207 kfree(tg->rt_se[i]);
208 }
209
210 kfree(tg->rt_rq);
211 kfree(tg->rt_se);
212}
213
214void init_tg_rt_entry(struct task_group *tg, struct rt_rq *rt_rq,
215 struct sched_rt_entity *rt_se, int cpu,
216 struct sched_rt_entity *parent)
217{
218 struct rq *rq = cpu_rq(cpu);
219
220 rt_rq->highest_prio.curr = MAX_RT_PRIO-1;
221 rt_rq->rt_nr_boosted = 0;
222 rt_rq->rq = rq;
223 rt_rq->tg = tg;
224
225 tg->rt_rq[cpu] = rt_rq;
226 tg->rt_se[cpu] = rt_se;
227
228 if (!rt_se)
229 return;
230
231 if (!parent)
232 rt_se->rt_rq = &rq->rt;
233 else
234 rt_se->rt_rq = parent->my_q;
235
236 rt_se->my_q = rt_rq;
237 rt_se->parent = parent;
238 INIT_LIST_HEAD(&rt_se->run_list);
239}
240
241int alloc_rt_sched_group(struct task_group *tg, struct task_group *parent)
242{
243 struct rt_rq *rt_rq;
244 struct sched_rt_entity *rt_se;
245 int i;
246
247 tg->rt_rq = kcalloc(nr_cpu_ids, sizeof(rt_rq), GFP_KERNEL);
248 if (!tg->rt_rq)
249 goto err;
250 tg->rt_se = kcalloc(nr_cpu_ids, sizeof(rt_se), GFP_KERNEL);
251 if (!tg->rt_se)
252 goto err;
253
254 init_rt_bandwidth(&tg->rt_bandwidth,
255 ktime_to_ns(def_rt_bandwidth.rt_period), 0);
256
257 for_each_possible_cpu(i) {
258 rt_rq = kzalloc_node(sizeof(struct rt_rq),
259 GFP_KERNEL, cpu_to_node(i));
260 if (!rt_rq)
261 goto err;
262
263 rt_se = kzalloc_node(sizeof(struct sched_rt_entity),
264 GFP_KERNEL, cpu_to_node(i));
265 if (!rt_se)
266 goto err_free_rq;
267
268 init_rt_rq(rt_rq);
269 rt_rq->rt_runtime = tg->rt_bandwidth.rt_runtime;
270 init_tg_rt_entry(tg, rt_rq, rt_se, i, parent->rt_se[i]);
271 }
272
273 return 1;
274
275err_free_rq:
276 kfree(rt_rq);
277err:
278 return 0;
279}
280
281#else /* CONFIG_RT_GROUP_SCHED */
282
283#define rt_entity_is_task(rt_se) (1)
284
285static inline struct task_struct *rt_task_of(struct sched_rt_entity *rt_se)
286{
287 return container_of(rt_se, struct task_struct, rt);
288}
289
290static inline struct rq *rq_of_rt_rq(struct rt_rq *rt_rq)
291{
292 return container_of(rt_rq, struct rq, rt);
293}
294
295static inline struct rq *rq_of_rt_se(struct sched_rt_entity *rt_se)
296{
297 struct task_struct *p = rt_task_of(rt_se);
298
299 return task_rq(p);
300}
301
302static inline struct rt_rq *rt_rq_of_se(struct sched_rt_entity *rt_se)
303{
304 struct rq *rq = rq_of_rt_se(rt_se);
305
306 return &rq->rt;
307}
308
309void unregister_rt_sched_group(struct task_group *tg) { }
310
311void free_rt_sched_group(struct task_group *tg) { }
312
313int alloc_rt_sched_group(struct task_group *tg, struct task_group *parent)
314{
315 return 1;
316}
317#endif /* CONFIG_RT_GROUP_SCHED */
318
319#ifdef CONFIG_SMP
320
321static inline bool need_pull_rt_task(struct rq *rq, struct task_struct *prev)
322{
323 /* Try to pull RT tasks here if we lower this rq's prio */
324 return rq->online && rq->rt.highest_prio.curr > prev->prio;
325}
326
327static inline int rt_overloaded(struct rq *rq)
328{
329 return atomic_read(&rq->rd->rto_count);
330}
331
332static inline void rt_set_overload(struct rq *rq)
333{
334 if (!rq->online)
335 return;
336
337 cpumask_set_cpu(rq->cpu, rq->rd->rto_mask);
338 /*
339 * Make sure the mask is visible before we set
340 * the overload count. That is checked to determine
341 * if we should look at the mask. It would be a shame
342 * if we looked at the mask, but the mask was not
343 * updated yet.
344 *
345 * Matched by the barrier in pull_rt_task().
346 */
347 smp_wmb();
348 atomic_inc(&rq->rd->rto_count);
349}
350
351static inline void rt_clear_overload(struct rq *rq)
352{
353 if (!rq->online)
354 return;
355
356 /* the order here really doesn't matter */
357 atomic_dec(&rq->rd->rto_count);
358 cpumask_clear_cpu(rq->cpu, rq->rd->rto_mask);
359}
360
361static void update_rt_migration(struct rt_rq *rt_rq)
362{
363 if (rt_rq->rt_nr_migratory && rt_rq->rt_nr_total > 1) {
364 if (!rt_rq->overloaded) {
365 rt_set_overload(rq_of_rt_rq(rt_rq));
366 rt_rq->overloaded = 1;
367 }
368 } else if (rt_rq->overloaded) {
369 rt_clear_overload(rq_of_rt_rq(rt_rq));
370 rt_rq->overloaded = 0;
371 }
372}
373
374static void inc_rt_migration(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
375{
376 struct task_struct *p;
377
378 if (!rt_entity_is_task(rt_se))
379 return;
380
381 p = rt_task_of(rt_se);
382 rt_rq = &rq_of_rt_rq(rt_rq)->rt;
383
384 rt_rq->rt_nr_total++;
385 if (p->nr_cpus_allowed > 1)
386 rt_rq->rt_nr_migratory++;
387
388 update_rt_migration(rt_rq);
389}
390
391static void dec_rt_migration(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
392{
393 struct task_struct *p;
394
395 if (!rt_entity_is_task(rt_se))
396 return;
397
398 p = rt_task_of(rt_se);
399 rt_rq = &rq_of_rt_rq(rt_rq)->rt;
400
401 rt_rq->rt_nr_total--;
402 if (p->nr_cpus_allowed > 1)
403 rt_rq->rt_nr_migratory--;
404
405 update_rt_migration(rt_rq);
406}
407
408static inline int has_pushable_tasks(struct rq *rq)
409{
410 return !plist_head_empty(&rq->rt.pushable_tasks);
411}
412
413static DEFINE_PER_CPU(struct balance_callback, rt_push_head);
414static DEFINE_PER_CPU(struct balance_callback, rt_pull_head);
415
416static void push_rt_tasks(struct rq *);
417static void pull_rt_task(struct rq *);
418
419static inline void rt_queue_push_tasks(struct rq *rq)
420{
421 if (!has_pushable_tasks(rq))
422 return;
423
424 queue_balance_callback(rq, &per_cpu(rt_push_head, rq->cpu), push_rt_tasks);
425}
426
427static inline void rt_queue_pull_task(struct rq *rq)
428{
429 queue_balance_callback(rq, &per_cpu(rt_pull_head, rq->cpu), pull_rt_task);
430}
431
432static void enqueue_pushable_task(struct rq *rq, struct task_struct *p)
433{
434 plist_del(&p->pushable_tasks, &rq->rt.pushable_tasks);
435 plist_node_init(&p->pushable_tasks, p->prio);
436 plist_add(&p->pushable_tasks, &rq->rt.pushable_tasks);
437
438 /* Update the highest prio pushable task */
439 if (p->prio < rq->rt.highest_prio.next)
440 rq->rt.highest_prio.next = p->prio;
441}
442
443static void dequeue_pushable_task(struct rq *rq, struct task_struct *p)
444{
445 plist_del(&p->pushable_tasks, &rq->rt.pushable_tasks);
446
447 /* Update the new highest prio pushable task */
448 if (has_pushable_tasks(rq)) {
449 p = plist_first_entry(&rq->rt.pushable_tasks,
450 struct task_struct, pushable_tasks);
451 rq->rt.highest_prio.next = p->prio;
452 } else {
453 rq->rt.highest_prio.next = MAX_RT_PRIO-1;
454 }
455}
456
457#else
458
459static inline void enqueue_pushable_task(struct rq *rq, struct task_struct *p)
460{
461}
462
463static inline void dequeue_pushable_task(struct rq *rq, struct task_struct *p)
464{
465}
466
467static inline
468void inc_rt_migration(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
469{
470}
471
472static inline
473void dec_rt_migration(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
474{
475}
476
477static inline void rt_queue_push_tasks(struct rq *rq)
478{
479}
480#endif /* CONFIG_SMP */
481
482static void enqueue_top_rt_rq(struct rt_rq *rt_rq);
483static void dequeue_top_rt_rq(struct rt_rq *rt_rq, unsigned int count);
484
485static inline int on_rt_rq(struct sched_rt_entity *rt_se)
486{
487 return rt_se->on_rq;
488}
489
490#ifdef CONFIG_UCLAMP_TASK
491/*
492 * Verify the fitness of task @p to run on @cpu taking into account the uclamp
493 * settings.
494 *
495 * This check is only important for heterogeneous systems where uclamp_min value
496 * is higher than the capacity of a @cpu. For non-heterogeneous system this
497 * function will always return true.
498 *
499 * The function will return true if the capacity of the @cpu is >= the
500 * uclamp_min and false otherwise.
501 *
502 * Note that uclamp_min will be clamped to uclamp_max if uclamp_min
503 * > uclamp_max.
504 */
505static inline bool rt_task_fits_capacity(struct task_struct *p, int cpu)
506{
507 unsigned int min_cap;
508 unsigned int max_cap;
509 unsigned int cpu_cap;
510
511 /* Only heterogeneous systems can benefit from this check */
512 if (!sched_asym_cpucap_active())
513 return true;
514
515 min_cap = uclamp_eff_value(p, UCLAMP_MIN);
516 max_cap = uclamp_eff_value(p, UCLAMP_MAX);
517
518 cpu_cap = capacity_orig_of(cpu);
519
520 return cpu_cap >= min(min_cap, max_cap);
521}
522#else
523static inline bool rt_task_fits_capacity(struct task_struct *p, int cpu)
524{
525 return true;
526}
527#endif
528
529#ifdef CONFIG_RT_GROUP_SCHED
530
531static inline u64 sched_rt_runtime(struct rt_rq *rt_rq)
532{
533 if (!rt_rq->tg)
534 return RUNTIME_INF;
535
536 return rt_rq->rt_runtime;
537}
538
539static inline u64 sched_rt_period(struct rt_rq *rt_rq)
540{
541 return ktime_to_ns(rt_rq->tg->rt_bandwidth.rt_period);
542}
543
544typedef struct task_group *rt_rq_iter_t;
545
546static inline struct task_group *next_task_group(struct task_group *tg)
547{
548 do {
549 tg = list_entry_rcu(tg->list.next,
550 typeof(struct task_group), list);
551 } while (&tg->list != &task_groups && task_group_is_autogroup(tg));
552
553 if (&tg->list == &task_groups)
554 tg = NULL;
555
556 return tg;
557}
558
559#define for_each_rt_rq(rt_rq, iter, rq) \
560 for (iter = container_of(&task_groups, typeof(*iter), list); \
561 (iter = next_task_group(iter)) && \
562 (rt_rq = iter->rt_rq[cpu_of(rq)]);)
563
564#define for_each_sched_rt_entity(rt_se) \
565 for (; rt_se; rt_se = rt_se->parent)
566
567static inline struct rt_rq *group_rt_rq(struct sched_rt_entity *rt_se)
568{
569 return rt_se->my_q;
570}
571
572static void enqueue_rt_entity(struct sched_rt_entity *rt_se, unsigned int flags);
573static void dequeue_rt_entity(struct sched_rt_entity *rt_se, unsigned int flags);
574
575static void sched_rt_rq_enqueue(struct rt_rq *rt_rq)
576{
577 struct task_struct *curr = rq_of_rt_rq(rt_rq)->curr;
578 struct rq *rq = rq_of_rt_rq(rt_rq);
579 struct sched_rt_entity *rt_se;
580
581 int cpu = cpu_of(rq);
582
583 rt_se = rt_rq->tg->rt_se[cpu];
584
585 if (rt_rq->rt_nr_running) {
586 if (!rt_se)
587 enqueue_top_rt_rq(rt_rq);
588 else if (!on_rt_rq(rt_se))
589 enqueue_rt_entity(rt_se, 0);
590
591 if (rt_rq->highest_prio.curr < curr->prio)
592 resched_curr(rq);
593 }
594}
595
596static void sched_rt_rq_dequeue(struct rt_rq *rt_rq)
597{
598 struct sched_rt_entity *rt_se;
599 int cpu = cpu_of(rq_of_rt_rq(rt_rq));
600
601 rt_se = rt_rq->tg->rt_se[cpu];
602
603 if (!rt_se) {
604 dequeue_top_rt_rq(rt_rq, rt_rq->rt_nr_running);
605 /* Kick cpufreq (see the comment in kernel/sched/sched.h). */
606 cpufreq_update_util(rq_of_rt_rq(rt_rq), 0);
607 }
608 else if (on_rt_rq(rt_se))
609 dequeue_rt_entity(rt_se, 0);
610}
611
612static inline int rt_rq_throttled(struct rt_rq *rt_rq)
613{
614 return rt_rq->rt_throttled && !rt_rq->rt_nr_boosted;
615}
616
617static int rt_se_boosted(struct sched_rt_entity *rt_se)
618{
619 struct rt_rq *rt_rq = group_rt_rq(rt_se);
620 struct task_struct *p;
621
622 if (rt_rq)
623 return !!rt_rq->rt_nr_boosted;
624
625 p = rt_task_of(rt_se);
626 return p->prio != p->normal_prio;
627}
628
629#ifdef CONFIG_SMP
630static inline const struct cpumask *sched_rt_period_mask(void)
631{
632 return this_rq()->rd->span;
633}
634#else
635static inline const struct cpumask *sched_rt_period_mask(void)
636{
637 return cpu_online_mask;
638}
639#endif
640
641static inline
642struct rt_rq *sched_rt_period_rt_rq(struct rt_bandwidth *rt_b, int cpu)
643{
644 return container_of(rt_b, struct task_group, rt_bandwidth)->rt_rq[cpu];
645}
646
647static inline struct rt_bandwidth *sched_rt_bandwidth(struct rt_rq *rt_rq)
648{
649 return &rt_rq->tg->rt_bandwidth;
650}
651
652#else /* !CONFIG_RT_GROUP_SCHED */
653
654static inline u64 sched_rt_runtime(struct rt_rq *rt_rq)
655{
656 return rt_rq->rt_runtime;
657}
658
659static inline u64 sched_rt_period(struct rt_rq *rt_rq)
660{
661 return ktime_to_ns(def_rt_bandwidth.rt_period);
662}
663
664typedef struct rt_rq *rt_rq_iter_t;
665
666#define for_each_rt_rq(rt_rq, iter, rq) \
667 for ((void) iter, rt_rq = &rq->rt; rt_rq; rt_rq = NULL)
668
669#define for_each_sched_rt_entity(rt_se) \
670 for (; rt_se; rt_se = NULL)
671
672static inline struct rt_rq *group_rt_rq(struct sched_rt_entity *rt_se)
673{
674 return NULL;
675}
676
677static inline void sched_rt_rq_enqueue(struct rt_rq *rt_rq)
678{
679 struct rq *rq = rq_of_rt_rq(rt_rq);
680
681 if (!rt_rq->rt_nr_running)
682 return;
683
684 enqueue_top_rt_rq(rt_rq);
685 resched_curr(rq);
686}
687
688static inline void sched_rt_rq_dequeue(struct rt_rq *rt_rq)
689{
690 dequeue_top_rt_rq(rt_rq, rt_rq->rt_nr_running);
691}
692
693static inline int rt_rq_throttled(struct rt_rq *rt_rq)
694{
695 return rt_rq->rt_throttled;
696}
697
698static inline const struct cpumask *sched_rt_period_mask(void)
699{
700 return cpu_online_mask;
701}
702
703static inline
704struct rt_rq *sched_rt_period_rt_rq(struct rt_bandwidth *rt_b, int cpu)
705{
706 return &cpu_rq(cpu)->rt;
707}
708
709static inline struct rt_bandwidth *sched_rt_bandwidth(struct rt_rq *rt_rq)
710{
711 return &def_rt_bandwidth;
712}
713
714#endif /* CONFIG_RT_GROUP_SCHED */
715
716bool sched_rt_bandwidth_account(struct rt_rq *rt_rq)
717{
718 struct rt_bandwidth *rt_b = sched_rt_bandwidth(rt_rq);
719
720 return (hrtimer_active(&rt_b->rt_period_timer) ||
721 rt_rq->rt_time < rt_b->rt_runtime);
722}
723
724#ifdef CONFIG_SMP
725/*
726 * We ran out of runtime, see if we can borrow some from our neighbours.
727 */
728static void do_balance_runtime(struct rt_rq *rt_rq)
729{
730 struct rt_bandwidth *rt_b = sched_rt_bandwidth(rt_rq);
731 struct root_domain *rd = rq_of_rt_rq(rt_rq)->rd;
732 int i, weight;
733 u64 rt_period;
734
735 weight = cpumask_weight(rd->span);
736
737 raw_spin_lock(&rt_b->rt_runtime_lock);
738 rt_period = ktime_to_ns(rt_b->rt_period);
739 for_each_cpu(i, rd->span) {
740 struct rt_rq *iter = sched_rt_period_rt_rq(rt_b, i);
741 s64 diff;
742
743 if (iter == rt_rq)
744 continue;
745
746 raw_spin_lock(&iter->rt_runtime_lock);
747 /*
748 * Either all rqs have inf runtime and there's nothing to steal
749 * or __disable_runtime() below sets a specific rq to inf to
750 * indicate its been disabled and disallow stealing.
751 */
752 if (iter->rt_runtime == RUNTIME_INF)
753 goto next;
754
755 /*
756 * From runqueues with spare time, take 1/n part of their
757 * spare time, but no more than our period.
758 */
759 diff = iter->rt_runtime - iter->rt_time;
760 if (diff > 0) {
761 diff = div_u64((u64)diff, weight);
762 if (rt_rq->rt_runtime + diff > rt_period)
763 diff = rt_period - rt_rq->rt_runtime;
764 iter->rt_runtime -= diff;
765 rt_rq->rt_runtime += diff;
766 if (rt_rq->rt_runtime == rt_period) {
767 raw_spin_unlock(&iter->rt_runtime_lock);
768 break;
769 }
770 }
771next:
772 raw_spin_unlock(&iter->rt_runtime_lock);
773 }
774 raw_spin_unlock(&rt_b->rt_runtime_lock);
775}
776
777/*
778 * Ensure this RQ takes back all the runtime it lend to its neighbours.
779 */
780static void __disable_runtime(struct rq *rq)
781{
782 struct root_domain *rd = rq->rd;
783 rt_rq_iter_t iter;
784 struct rt_rq *rt_rq;
785
786 if (unlikely(!scheduler_running))
787 return;
788
789 for_each_rt_rq(rt_rq, iter, rq) {
790 struct rt_bandwidth *rt_b = sched_rt_bandwidth(rt_rq);
791 s64 want;
792 int i;
793
794 raw_spin_lock(&rt_b->rt_runtime_lock);
795 raw_spin_lock(&rt_rq->rt_runtime_lock);
796 /*
797 * Either we're all inf and nobody needs to borrow, or we're
798 * already disabled and thus have nothing to do, or we have
799 * exactly the right amount of runtime to take out.
800 */
801 if (rt_rq->rt_runtime == RUNTIME_INF ||
802 rt_rq->rt_runtime == rt_b->rt_runtime)
803 goto balanced;
804 raw_spin_unlock(&rt_rq->rt_runtime_lock);
805
806 /*
807 * Calculate the difference between what we started out with
808 * and what we current have, that's the amount of runtime
809 * we lend and now have to reclaim.
810 */
811 want = rt_b->rt_runtime - rt_rq->rt_runtime;
812
813 /*
814 * Greedy reclaim, take back as much as we can.
815 */
816 for_each_cpu(i, rd->span) {
817 struct rt_rq *iter = sched_rt_period_rt_rq(rt_b, i);
818 s64 diff;
819
820 /*
821 * Can't reclaim from ourselves or disabled runqueues.
822 */
823 if (iter == rt_rq || iter->rt_runtime == RUNTIME_INF)
824 continue;
825
826 raw_spin_lock(&iter->rt_runtime_lock);
827 if (want > 0) {
828 diff = min_t(s64, iter->rt_runtime, want);
829 iter->rt_runtime -= diff;
830 want -= diff;
831 } else {
832 iter->rt_runtime -= want;
833 want -= want;
834 }
835 raw_spin_unlock(&iter->rt_runtime_lock);
836
837 if (!want)
838 break;
839 }
840
841 raw_spin_lock(&rt_rq->rt_runtime_lock);
842 /*
843 * We cannot be left wanting - that would mean some runtime
844 * leaked out of the system.
845 */
846 WARN_ON_ONCE(want);
847balanced:
848 /*
849 * Disable all the borrow logic by pretending we have inf
850 * runtime - in which case borrowing doesn't make sense.
851 */
852 rt_rq->rt_runtime = RUNTIME_INF;
853 rt_rq->rt_throttled = 0;
854 raw_spin_unlock(&rt_rq->rt_runtime_lock);
855 raw_spin_unlock(&rt_b->rt_runtime_lock);
856
857 /* Make rt_rq available for pick_next_task() */
858 sched_rt_rq_enqueue(rt_rq);
859 }
860}
861
862static void __enable_runtime(struct rq *rq)
863{
864 rt_rq_iter_t iter;
865 struct rt_rq *rt_rq;
866
867 if (unlikely(!scheduler_running))
868 return;
869
870 /*
871 * Reset each runqueue's bandwidth settings
872 */
873 for_each_rt_rq(rt_rq, iter, rq) {
874 struct rt_bandwidth *rt_b = sched_rt_bandwidth(rt_rq);
875
876 raw_spin_lock(&rt_b->rt_runtime_lock);
877 raw_spin_lock(&rt_rq->rt_runtime_lock);
878 rt_rq->rt_runtime = rt_b->rt_runtime;
879 rt_rq->rt_time = 0;
880 rt_rq->rt_throttled = 0;
881 raw_spin_unlock(&rt_rq->rt_runtime_lock);
882 raw_spin_unlock(&rt_b->rt_runtime_lock);
883 }
884}
885
886static void balance_runtime(struct rt_rq *rt_rq)
887{
888 if (!sched_feat(RT_RUNTIME_SHARE))
889 return;
890
891 if (rt_rq->rt_time > rt_rq->rt_runtime) {
892 raw_spin_unlock(&rt_rq->rt_runtime_lock);
893 do_balance_runtime(rt_rq);
894 raw_spin_lock(&rt_rq->rt_runtime_lock);
895 }
896}
897#else /* !CONFIG_SMP */
898static inline void balance_runtime(struct rt_rq *rt_rq) {}
899#endif /* CONFIG_SMP */
900
901static int do_sched_rt_period_timer(struct rt_bandwidth *rt_b, int overrun)
902{
903 int i, idle = 1, throttled = 0;
904 const struct cpumask *span;
905
906 span = sched_rt_period_mask();
907#ifdef CONFIG_RT_GROUP_SCHED
908 /*
909 * FIXME: isolated CPUs should really leave the root task group,
910 * whether they are isolcpus or were isolated via cpusets, lest
911 * the timer run on a CPU which does not service all runqueues,
912 * potentially leaving other CPUs indefinitely throttled. If
913 * isolation is really required, the user will turn the throttle
914 * off to kill the perturbations it causes anyway. Meanwhile,
915 * this maintains functionality for boot and/or troubleshooting.
916 */
917 if (rt_b == &root_task_group.rt_bandwidth)
918 span = cpu_online_mask;
919#endif
920 for_each_cpu(i, span) {
921 int enqueue = 0;
922 struct rt_rq *rt_rq = sched_rt_period_rt_rq(rt_b, i);
923 struct rq *rq = rq_of_rt_rq(rt_rq);
924 struct rq_flags rf;
925 int skip;
926
927 /*
928 * When span == cpu_online_mask, taking each rq->lock
929 * can be time-consuming. Try to avoid it when possible.
930 */
931 raw_spin_lock(&rt_rq->rt_runtime_lock);
932 if (!sched_feat(RT_RUNTIME_SHARE) && rt_rq->rt_runtime != RUNTIME_INF)
933 rt_rq->rt_runtime = rt_b->rt_runtime;
934 skip = !rt_rq->rt_time && !rt_rq->rt_nr_running;
935 raw_spin_unlock(&rt_rq->rt_runtime_lock);
936 if (skip)
937 continue;
938
939 rq_lock(rq, &rf);
940 update_rq_clock(rq);
941
942 if (rt_rq->rt_time) {
943 u64 runtime;
944
945 raw_spin_lock(&rt_rq->rt_runtime_lock);
946 if (rt_rq->rt_throttled)
947 balance_runtime(rt_rq);
948 runtime = rt_rq->rt_runtime;
949 rt_rq->rt_time -= min(rt_rq->rt_time, overrun*runtime);
950 if (rt_rq->rt_throttled && rt_rq->rt_time < runtime) {
951 rt_rq->rt_throttled = 0;
952 enqueue = 1;
953
954 /*
955 * When we're idle and a woken (rt) task is
956 * throttled check_preempt_curr() will set
957 * skip_update and the time between the wakeup
958 * and this unthrottle will get accounted as
959 * 'runtime'.
960 */
961 if (rt_rq->rt_nr_running && rq->curr == rq->idle)
962 rq_clock_cancel_skipupdate(rq);
963 }
964 if (rt_rq->rt_time || rt_rq->rt_nr_running)
965 idle = 0;
966 raw_spin_unlock(&rt_rq->rt_runtime_lock);
967 } else if (rt_rq->rt_nr_running) {
968 idle = 0;
969 if (!rt_rq_throttled(rt_rq))
970 enqueue = 1;
971 }
972 if (rt_rq->rt_throttled)
973 throttled = 1;
974
975 if (enqueue)
976 sched_rt_rq_enqueue(rt_rq);
977 rq_unlock(rq, &rf);
978 }
979
980 if (!throttled && (!rt_bandwidth_enabled() || rt_b->rt_runtime == RUNTIME_INF))
981 return 1;
982
983 return idle;
984}
985
986static inline int rt_se_prio(struct sched_rt_entity *rt_se)
987{
988#ifdef CONFIG_RT_GROUP_SCHED
989 struct rt_rq *rt_rq = group_rt_rq(rt_se);
990
991 if (rt_rq)
992 return rt_rq->highest_prio.curr;
993#endif
994
995 return rt_task_of(rt_se)->prio;
996}
997
998static int sched_rt_runtime_exceeded(struct rt_rq *rt_rq)
999{
1000 u64 runtime = sched_rt_runtime(rt_rq);
1001
1002 if (rt_rq->rt_throttled)
1003 return rt_rq_throttled(rt_rq);
1004
1005 if (runtime >= sched_rt_period(rt_rq))
1006 return 0;
1007
1008 balance_runtime(rt_rq);
1009 runtime = sched_rt_runtime(rt_rq);
1010 if (runtime == RUNTIME_INF)
1011 return 0;
1012
1013 if (rt_rq->rt_time > runtime) {
1014 struct rt_bandwidth *rt_b = sched_rt_bandwidth(rt_rq);
1015
1016 /*
1017 * Don't actually throttle groups that have no runtime assigned
1018 * but accrue some time due to boosting.
1019 */
1020 if (likely(rt_b->rt_runtime)) {
1021 rt_rq->rt_throttled = 1;
1022 printk_deferred_once("sched: RT throttling activated\n");
1023 } else {
1024 /*
1025 * In case we did anyway, make it go away,
1026 * replenishment is a joke, since it will replenish us
1027 * with exactly 0 ns.
1028 */
1029 rt_rq->rt_time = 0;
1030 }
1031
1032 if (rt_rq_throttled(rt_rq)) {
1033 sched_rt_rq_dequeue(rt_rq);
1034 return 1;
1035 }
1036 }
1037
1038 return 0;
1039}
1040
1041/*
1042 * Update the current task's runtime statistics. Skip current tasks that
1043 * are not in our scheduling class.
1044 */
1045static void update_curr_rt(struct rq *rq)
1046{
1047 struct task_struct *curr = rq->curr;
1048 struct sched_rt_entity *rt_se = &curr->rt;
1049 u64 delta_exec;
1050 u64 now;
1051
1052 if (curr->sched_class != &rt_sched_class)
1053 return;
1054
1055 now = rq_clock_task(rq);
1056 delta_exec = now - curr->se.exec_start;
1057 if (unlikely((s64)delta_exec <= 0))
1058 return;
1059
1060 schedstat_set(curr->stats.exec_max,
1061 max(curr->stats.exec_max, delta_exec));
1062
1063 trace_sched_stat_runtime(curr, delta_exec, 0);
1064
1065 update_current_exec_runtime(curr, now, delta_exec);
1066
1067 if (!rt_bandwidth_enabled())
1068 return;
1069
1070 for_each_sched_rt_entity(rt_se) {
1071 struct rt_rq *rt_rq = rt_rq_of_se(rt_se);
1072 int exceeded;
1073
1074 if (sched_rt_runtime(rt_rq) != RUNTIME_INF) {
1075 raw_spin_lock(&rt_rq->rt_runtime_lock);
1076 rt_rq->rt_time += delta_exec;
1077 exceeded = sched_rt_runtime_exceeded(rt_rq);
1078 if (exceeded)
1079 resched_curr(rq);
1080 raw_spin_unlock(&rt_rq->rt_runtime_lock);
1081 if (exceeded)
1082 do_start_rt_bandwidth(sched_rt_bandwidth(rt_rq));
1083 }
1084 }
1085}
1086
1087static void
1088dequeue_top_rt_rq(struct rt_rq *rt_rq, unsigned int count)
1089{
1090 struct rq *rq = rq_of_rt_rq(rt_rq);
1091
1092 BUG_ON(&rq->rt != rt_rq);
1093
1094 if (!rt_rq->rt_queued)
1095 return;
1096
1097 BUG_ON(!rq->nr_running);
1098
1099 sub_nr_running(rq, count);
1100 rt_rq->rt_queued = 0;
1101
1102}
1103
1104static void
1105enqueue_top_rt_rq(struct rt_rq *rt_rq)
1106{
1107 struct rq *rq = rq_of_rt_rq(rt_rq);
1108
1109 BUG_ON(&rq->rt != rt_rq);
1110
1111 if (rt_rq->rt_queued)
1112 return;
1113
1114 if (rt_rq_throttled(rt_rq))
1115 return;
1116
1117 if (rt_rq->rt_nr_running) {
1118 add_nr_running(rq, rt_rq->rt_nr_running);
1119 rt_rq->rt_queued = 1;
1120 }
1121
1122 /* Kick cpufreq (see the comment in kernel/sched/sched.h). */
1123 cpufreq_update_util(rq, 0);
1124}
1125
1126#if defined CONFIG_SMP
1127
1128static void
1129inc_rt_prio_smp(struct rt_rq *rt_rq, int prio, int prev_prio)
1130{
1131 struct rq *rq = rq_of_rt_rq(rt_rq);
1132
1133#ifdef CONFIG_RT_GROUP_SCHED
1134 /*
1135 * Change rq's cpupri only if rt_rq is the top queue.
1136 */
1137 if (&rq->rt != rt_rq)
1138 return;
1139#endif
1140 if (rq->online && prio < prev_prio)
1141 cpupri_set(&rq->rd->cpupri, rq->cpu, prio);
1142}
1143
1144static void
1145dec_rt_prio_smp(struct rt_rq *rt_rq, int prio, int prev_prio)
1146{
1147 struct rq *rq = rq_of_rt_rq(rt_rq);
1148
1149#ifdef CONFIG_RT_GROUP_SCHED
1150 /*
1151 * Change rq's cpupri only if rt_rq is the top queue.
1152 */
1153 if (&rq->rt != rt_rq)
1154 return;
1155#endif
1156 if (rq->online && rt_rq->highest_prio.curr != prev_prio)
1157 cpupri_set(&rq->rd->cpupri, rq->cpu, rt_rq->highest_prio.curr);
1158}
1159
1160#else /* CONFIG_SMP */
1161
1162static inline
1163void inc_rt_prio_smp(struct rt_rq *rt_rq, int prio, int prev_prio) {}
1164static inline
1165void dec_rt_prio_smp(struct rt_rq *rt_rq, int prio, int prev_prio) {}
1166
1167#endif /* CONFIG_SMP */
1168
1169#if defined CONFIG_SMP || defined CONFIG_RT_GROUP_SCHED
1170static void
1171inc_rt_prio(struct rt_rq *rt_rq, int prio)
1172{
1173 int prev_prio = rt_rq->highest_prio.curr;
1174
1175 if (prio < prev_prio)
1176 rt_rq->highest_prio.curr = prio;
1177
1178 inc_rt_prio_smp(rt_rq, prio, prev_prio);
1179}
1180
1181static void
1182dec_rt_prio(struct rt_rq *rt_rq, int prio)
1183{
1184 int prev_prio = rt_rq->highest_prio.curr;
1185
1186 if (rt_rq->rt_nr_running) {
1187
1188 WARN_ON(prio < prev_prio);
1189
1190 /*
1191 * This may have been our highest task, and therefore
1192 * we may have some recomputation to do
1193 */
1194 if (prio == prev_prio) {
1195 struct rt_prio_array *array = &rt_rq->active;
1196
1197 rt_rq->highest_prio.curr =
1198 sched_find_first_bit(array->bitmap);
1199 }
1200
1201 } else {
1202 rt_rq->highest_prio.curr = MAX_RT_PRIO-1;
1203 }
1204
1205 dec_rt_prio_smp(rt_rq, prio, prev_prio);
1206}
1207
1208#else
1209
1210static inline void inc_rt_prio(struct rt_rq *rt_rq, int prio) {}
1211static inline void dec_rt_prio(struct rt_rq *rt_rq, int prio) {}
1212
1213#endif /* CONFIG_SMP || CONFIG_RT_GROUP_SCHED */
1214
1215#ifdef CONFIG_RT_GROUP_SCHED
1216
1217static void
1218inc_rt_group(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
1219{
1220 if (rt_se_boosted(rt_se))
1221 rt_rq->rt_nr_boosted++;
1222
1223 if (rt_rq->tg)
1224 start_rt_bandwidth(&rt_rq->tg->rt_bandwidth);
1225}
1226
1227static void
1228dec_rt_group(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
1229{
1230 if (rt_se_boosted(rt_se))
1231 rt_rq->rt_nr_boosted--;
1232
1233 WARN_ON(!rt_rq->rt_nr_running && rt_rq->rt_nr_boosted);
1234}
1235
1236#else /* CONFIG_RT_GROUP_SCHED */
1237
1238static void
1239inc_rt_group(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
1240{
1241 start_rt_bandwidth(&def_rt_bandwidth);
1242}
1243
1244static inline
1245void dec_rt_group(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq) {}
1246
1247#endif /* CONFIG_RT_GROUP_SCHED */
1248
1249static inline
1250unsigned int rt_se_nr_running(struct sched_rt_entity *rt_se)
1251{
1252 struct rt_rq *group_rq = group_rt_rq(rt_se);
1253
1254 if (group_rq)
1255 return group_rq->rt_nr_running;
1256 else
1257 return 1;
1258}
1259
1260static inline
1261unsigned int rt_se_rr_nr_running(struct sched_rt_entity *rt_se)
1262{
1263 struct rt_rq *group_rq = group_rt_rq(rt_se);
1264 struct task_struct *tsk;
1265
1266 if (group_rq)
1267 return group_rq->rr_nr_running;
1268
1269 tsk = rt_task_of(rt_se);
1270
1271 return (tsk->policy == SCHED_RR) ? 1 : 0;
1272}
1273
1274static inline
1275void inc_rt_tasks(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
1276{
1277 int prio = rt_se_prio(rt_se);
1278
1279 WARN_ON(!rt_prio(prio));
1280 rt_rq->rt_nr_running += rt_se_nr_running(rt_se);
1281 rt_rq->rr_nr_running += rt_se_rr_nr_running(rt_se);
1282
1283 inc_rt_prio(rt_rq, prio);
1284 inc_rt_migration(rt_se, rt_rq);
1285 inc_rt_group(rt_se, rt_rq);
1286}
1287
1288static inline
1289void dec_rt_tasks(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
1290{
1291 WARN_ON(!rt_prio(rt_se_prio(rt_se)));
1292 WARN_ON(!rt_rq->rt_nr_running);
1293 rt_rq->rt_nr_running -= rt_se_nr_running(rt_se);
1294 rt_rq->rr_nr_running -= rt_se_rr_nr_running(rt_se);
1295
1296 dec_rt_prio(rt_rq, rt_se_prio(rt_se));
1297 dec_rt_migration(rt_se, rt_rq);
1298 dec_rt_group(rt_se, rt_rq);
1299}
1300
1301/*
1302 * Change rt_se->run_list location unless SAVE && !MOVE
1303 *
1304 * assumes ENQUEUE/DEQUEUE flags match
1305 */
1306static inline bool move_entity(unsigned int flags)
1307{
1308 if ((flags & (DEQUEUE_SAVE | DEQUEUE_MOVE)) == DEQUEUE_SAVE)
1309 return false;
1310
1311 return true;
1312}
1313
1314static void __delist_rt_entity(struct sched_rt_entity *rt_se, struct rt_prio_array *array)
1315{
1316 list_del_init(&rt_se->run_list);
1317
1318 if (list_empty(array->queue + rt_se_prio(rt_se)))
1319 __clear_bit(rt_se_prio(rt_se), array->bitmap);
1320
1321 rt_se->on_list = 0;
1322}
1323
1324static inline struct sched_statistics *
1325__schedstats_from_rt_se(struct sched_rt_entity *rt_se)
1326{
1327#ifdef CONFIG_RT_GROUP_SCHED
1328 /* schedstats is not supported for rt group. */
1329 if (!rt_entity_is_task(rt_se))
1330 return NULL;
1331#endif
1332
1333 return &rt_task_of(rt_se)->stats;
1334}
1335
1336static inline void
1337update_stats_wait_start_rt(struct rt_rq *rt_rq, struct sched_rt_entity *rt_se)
1338{
1339 struct sched_statistics *stats;
1340 struct task_struct *p = NULL;
1341
1342 if (!schedstat_enabled())
1343 return;
1344
1345 if (rt_entity_is_task(rt_se))
1346 p = rt_task_of(rt_se);
1347
1348 stats = __schedstats_from_rt_se(rt_se);
1349 if (!stats)
1350 return;
1351
1352 __update_stats_wait_start(rq_of_rt_rq(rt_rq), p, stats);
1353}
1354
1355static inline void
1356update_stats_enqueue_sleeper_rt(struct rt_rq *rt_rq, struct sched_rt_entity *rt_se)
1357{
1358 struct sched_statistics *stats;
1359 struct task_struct *p = NULL;
1360
1361 if (!schedstat_enabled())
1362 return;
1363
1364 if (rt_entity_is_task(rt_se))
1365 p = rt_task_of(rt_se);
1366
1367 stats = __schedstats_from_rt_se(rt_se);
1368 if (!stats)
1369 return;
1370
1371 __update_stats_enqueue_sleeper(rq_of_rt_rq(rt_rq), p, stats);
1372}
1373
1374static inline void
1375update_stats_enqueue_rt(struct rt_rq *rt_rq, struct sched_rt_entity *rt_se,
1376 int flags)
1377{
1378 if (!schedstat_enabled())
1379 return;
1380
1381 if (flags & ENQUEUE_WAKEUP)
1382 update_stats_enqueue_sleeper_rt(rt_rq, rt_se);
1383}
1384
1385static inline void
1386update_stats_wait_end_rt(struct rt_rq *rt_rq, struct sched_rt_entity *rt_se)
1387{
1388 struct sched_statistics *stats;
1389 struct task_struct *p = NULL;
1390
1391 if (!schedstat_enabled())
1392 return;
1393
1394 if (rt_entity_is_task(rt_se))
1395 p = rt_task_of(rt_se);
1396
1397 stats = __schedstats_from_rt_se(rt_se);
1398 if (!stats)
1399 return;
1400
1401 __update_stats_wait_end(rq_of_rt_rq(rt_rq), p, stats);
1402}
1403
1404static inline void
1405update_stats_dequeue_rt(struct rt_rq *rt_rq, struct sched_rt_entity *rt_se,
1406 int flags)
1407{
1408 struct task_struct *p = NULL;
1409
1410 if (!schedstat_enabled())
1411 return;
1412
1413 if (rt_entity_is_task(rt_se))
1414 p = rt_task_of(rt_se);
1415
1416 if ((flags & DEQUEUE_SLEEP) && p) {
1417 unsigned int state;
1418
1419 state = READ_ONCE(p->__state);
1420 if (state & TASK_INTERRUPTIBLE)
1421 __schedstat_set(p->stats.sleep_start,
1422 rq_clock(rq_of_rt_rq(rt_rq)));
1423
1424 if (state & TASK_UNINTERRUPTIBLE)
1425 __schedstat_set(p->stats.block_start,
1426 rq_clock(rq_of_rt_rq(rt_rq)));
1427 }
1428}
1429
1430static void __enqueue_rt_entity(struct sched_rt_entity *rt_se, unsigned int flags)
1431{
1432 struct rt_rq *rt_rq = rt_rq_of_se(rt_se);
1433 struct rt_prio_array *array = &rt_rq->active;
1434 struct rt_rq *group_rq = group_rt_rq(rt_se);
1435 struct list_head *queue = array->queue + rt_se_prio(rt_se);
1436
1437 /*
1438 * Don't enqueue the group if its throttled, or when empty.
1439 * The latter is a consequence of the former when a child group
1440 * get throttled and the current group doesn't have any other
1441 * active members.
1442 */
1443 if (group_rq && (rt_rq_throttled(group_rq) || !group_rq->rt_nr_running)) {
1444 if (rt_se->on_list)
1445 __delist_rt_entity(rt_se, array);
1446 return;
1447 }
1448
1449 if (move_entity(flags)) {
1450 WARN_ON_ONCE(rt_se->on_list);
1451 if (flags & ENQUEUE_HEAD)
1452 list_add(&rt_se->run_list, queue);
1453 else
1454 list_add_tail(&rt_se->run_list, queue);
1455
1456 __set_bit(rt_se_prio(rt_se), array->bitmap);
1457 rt_se->on_list = 1;
1458 }
1459 rt_se->on_rq = 1;
1460
1461 inc_rt_tasks(rt_se, rt_rq);
1462}
1463
1464static void __dequeue_rt_entity(struct sched_rt_entity *rt_se, unsigned int flags)
1465{
1466 struct rt_rq *rt_rq = rt_rq_of_se(rt_se);
1467 struct rt_prio_array *array = &rt_rq->active;
1468
1469 if (move_entity(flags)) {
1470 WARN_ON_ONCE(!rt_se->on_list);
1471 __delist_rt_entity(rt_se, array);
1472 }
1473 rt_se->on_rq = 0;
1474
1475 dec_rt_tasks(rt_se, rt_rq);
1476}
1477
1478/*
1479 * Because the prio of an upper entry depends on the lower
1480 * entries, we must remove entries top - down.
1481 */
1482static void dequeue_rt_stack(struct sched_rt_entity *rt_se, unsigned int flags)
1483{
1484 struct sched_rt_entity *back = NULL;
1485 unsigned int rt_nr_running;
1486
1487 for_each_sched_rt_entity(rt_se) {
1488 rt_se->back = back;
1489 back = rt_se;
1490 }
1491
1492 rt_nr_running = rt_rq_of_se(back)->rt_nr_running;
1493
1494 for (rt_se = back; rt_se; rt_se = rt_se->back) {
1495 if (on_rt_rq(rt_se))
1496 __dequeue_rt_entity(rt_se, flags);
1497 }
1498
1499 dequeue_top_rt_rq(rt_rq_of_se(back), rt_nr_running);
1500}
1501
1502static void enqueue_rt_entity(struct sched_rt_entity *rt_se, unsigned int flags)
1503{
1504 struct rq *rq = rq_of_rt_se(rt_se);
1505
1506 update_stats_enqueue_rt(rt_rq_of_se(rt_se), rt_se, flags);
1507
1508 dequeue_rt_stack(rt_se, flags);
1509 for_each_sched_rt_entity(rt_se)
1510 __enqueue_rt_entity(rt_se, flags);
1511 enqueue_top_rt_rq(&rq->rt);
1512}
1513
1514static void dequeue_rt_entity(struct sched_rt_entity *rt_se, unsigned int flags)
1515{
1516 struct rq *rq = rq_of_rt_se(rt_se);
1517
1518 update_stats_dequeue_rt(rt_rq_of_se(rt_se), rt_se, flags);
1519
1520 dequeue_rt_stack(rt_se, flags);
1521
1522 for_each_sched_rt_entity(rt_se) {
1523 struct rt_rq *rt_rq = group_rt_rq(rt_se);
1524
1525 if (rt_rq && rt_rq->rt_nr_running)
1526 __enqueue_rt_entity(rt_se, flags);
1527 }
1528 enqueue_top_rt_rq(&rq->rt);
1529}
1530
1531/*
1532 * Adding/removing a task to/from a priority array:
1533 */
1534static void
1535enqueue_task_rt(struct rq *rq, struct task_struct *p, int flags)
1536{
1537 struct sched_rt_entity *rt_se = &p->rt;
1538
1539 if (flags & ENQUEUE_WAKEUP)
1540 rt_se->timeout = 0;
1541
1542 check_schedstat_required();
1543 update_stats_wait_start_rt(rt_rq_of_se(rt_se), rt_se);
1544
1545 enqueue_rt_entity(rt_se, flags);
1546
1547 if (!task_current(rq, p) && p->nr_cpus_allowed > 1)
1548 enqueue_pushable_task(rq, p);
1549}
1550
1551static void dequeue_task_rt(struct rq *rq, struct task_struct *p, int flags)
1552{
1553 struct sched_rt_entity *rt_se = &p->rt;
1554
1555 update_curr_rt(rq);
1556 dequeue_rt_entity(rt_se, flags);
1557
1558 dequeue_pushable_task(rq, p);
1559}
1560
1561/*
1562 * Put task to the head or the end of the run list without the overhead of
1563 * dequeue followed by enqueue.
1564 */
1565static void
1566requeue_rt_entity(struct rt_rq *rt_rq, struct sched_rt_entity *rt_se, int head)
1567{
1568 if (on_rt_rq(rt_se)) {
1569 struct rt_prio_array *array = &rt_rq->active;
1570 struct list_head *queue = array->queue + rt_se_prio(rt_se);
1571
1572 if (head)
1573 list_move(&rt_se->run_list, queue);
1574 else
1575 list_move_tail(&rt_se->run_list, queue);
1576 }
1577}
1578
1579static void requeue_task_rt(struct rq *rq, struct task_struct *p, int head)
1580{
1581 struct sched_rt_entity *rt_se = &p->rt;
1582 struct rt_rq *rt_rq;
1583
1584 for_each_sched_rt_entity(rt_se) {
1585 rt_rq = rt_rq_of_se(rt_se);
1586 requeue_rt_entity(rt_rq, rt_se, head);
1587 }
1588}
1589
1590static void yield_task_rt(struct rq *rq)
1591{
1592 requeue_task_rt(rq, rq->curr, 0);
1593}
1594
1595#ifdef CONFIG_SMP
1596static int find_lowest_rq(struct task_struct *task);
1597
1598static int
1599select_task_rq_rt(struct task_struct *p, int cpu, int flags)
1600{
1601 struct task_struct *curr;
1602 struct rq *rq;
1603 bool test;
1604
1605 /* For anything but wake ups, just return the task_cpu */
1606 if (!(flags & (WF_TTWU | WF_FORK)))
1607 goto out;
1608
1609 rq = cpu_rq(cpu);
1610
1611 rcu_read_lock();
1612 curr = READ_ONCE(rq->curr); /* unlocked access */
1613
1614 /*
1615 * If the current task on @p's runqueue is an RT task, then
1616 * try to see if we can wake this RT task up on another
1617 * runqueue. Otherwise simply start this RT task
1618 * on its current runqueue.
1619 *
1620 * We want to avoid overloading runqueues. If the woken
1621 * task is a higher priority, then it will stay on this CPU
1622 * and the lower prio task should be moved to another CPU.
1623 * Even though this will probably make the lower prio task
1624 * lose its cache, we do not want to bounce a higher task
1625 * around just because it gave up its CPU, perhaps for a
1626 * lock?
1627 *
1628 * For equal prio tasks, we just let the scheduler sort it out.
1629 *
1630 * Otherwise, just let it ride on the affined RQ and the
1631 * post-schedule router will push the preempted task away
1632 *
1633 * This test is optimistic, if we get it wrong the load-balancer
1634 * will have to sort it out.
1635 *
1636 * We take into account the capacity of the CPU to ensure it fits the
1637 * requirement of the task - which is only important on heterogeneous
1638 * systems like big.LITTLE.
1639 */
1640 test = curr &&
1641 unlikely(rt_task(curr)) &&
1642 (curr->nr_cpus_allowed < 2 || curr->prio <= p->prio);
1643
1644 if (test || !rt_task_fits_capacity(p, cpu)) {
1645 int target = find_lowest_rq(p);
1646
1647 /*
1648 * Bail out if we were forcing a migration to find a better
1649 * fitting CPU but our search failed.
1650 */
1651 if (!test && target != -1 && !rt_task_fits_capacity(p, target))
1652 goto out_unlock;
1653
1654 /*
1655 * Don't bother moving it if the destination CPU is
1656 * not running a lower priority task.
1657 */
1658 if (target != -1 &&
1659 p->prio < cpu_rq(target)->rt.highest_prio.curr)
1660 cpu = target;
1661 }
1662
1663out_unlock:
1664 rcu_read_unlock();
1665
1666out:
1667 return cpu;
1668}
1669
1670static void check_preempt_equal_prio(struct rq *rq, struct task_struct *p)
1671{
1672 /*
1673 * Current can't be migrated, useless to reschedule,
1674 * let's hope p can move out.
1675 */
1676 if (rq->curr->nr_cpus_allowed == 1 ||
1677 !cpupri_find(&rq->rd->cpupri, rq->curr, NULL))
1678 return;
1679
1680 /*
1681 * p is migratable, so let's not schedule it and
1682 * see if it is pushed or pulled somewhere else.
1683 */
1684 if (p->nr_cpus_allowed != 1 &&
1685 cpupri_find(&rq->rd->cpupri, p, NULL))
1686 return;
1687
1688 /*
1689 * There appear to be other CPUs that can accept
1690 * the current task but none can run 'p', so lets reschedule
1691 * to try and push the current task away:
1692 */
1693 requeue_task_rt(rq, p, 1);
1694 resched_curr(rq);
1695}
1696
1697static int balance_rt(struct rq *rq, struct task_struct *p, struct rq_flags *rf)
1698{
1699 if (!on_rt_rq(&p->rt) && need_pull_rt_task(rq, p)) {
1700 /*
1701 * This is OK, because current is on_cpu, which avoids it being
1702 * picked for load-balance and preemption/IRQs are still
1703 * disabled avoiding further scheduler activity on it and we've
1704 * not yet started the picking loop.
1705 */
1706 rq_unpin_lock(rq, rf);
1707 pull_rt_task(rq);
1708 rq_repin_lock(rq, rf);
1709 }
1710
1711 return sched_stop_runnable(rq) || sched_dl_runnable(rq) || sched_rt_runnable(rq);
1712}
1713#endif /* CONFIG_SMP */
1714
1715/*
1716 * Preempt the current task with a newly woken task if needed:
1717 */
1718static void check_preempt_curr_rt(struct rq *rq, struct task_struct *p, int flags)
1719{
1720 if (p->prio < rq->curr->prio) {
1721 resched_curr(rq);
1722 return;
1723 }
1724
1725#ifdef CONFIG_SMP
1726 /*
1727 * If:
1728 *
1729 * - the newly woken task is of equal priority to the current task
1730 * - the newly woken task is non-migratable while current is migratable
1731 * - current will be preempted on the next reschedule
1732 *
1733 * we should check to see if current can readily move to a different
1734 * cpu. If so, we will reschedule to allow the push logic to try
1735 * to move current somewhere else, making room for our non-migratable
1736 * task.
1737 */
1738 if (p->prio == rq->curr->prio && !test_tsk_need_resched(rq->curr))
1739 check_preempt_equal_prio(rq, p);
1740#endif
1741}
1742
1743static inline void set_next_task_rt(struct rq *rq, struct task_struct *p, bool first)
1744{
1745 struct sched_rt_entity *rt_se = &p->rt;
1746 struct rt_rq *rt_rq = &rq->rt;
1747
1748 p->se.exec_start = rq_clock_task(rq);
1749 if (on_rt_rq(&p->rt))
1750 update_stats_wait_end_rt(rt_rq, rt_se);
1751
1752 /* The running task is never eligible for pushing */
1753 dequeue_pushable_task(rq, p);
1754
1755 if (!first)
1756 return;
1757
1758 /*
1759 * If prev task was rt, put_prev_task() has already updated the
1760 * utilization. We only care of the case where we start to schedule a
1761 * rt task
1762 */
1763 if (rq->curr->sched_class != &rt_sched_class)
1764 update_rt_rq_load_avg(rq_clock_pelt(rq), rq, 0);
1765
1766 rt_queue_push_tasks(rq);
1767}
1768
1769static struct sched_rt_entity *pick_next_rt_entity(struct rt_rq *rt_rq)
1770{
1771 struct rt_prio_array *array = &rt_rq->active;
1772 struct sched_rt_entity *next = NULL;
1773 struct list_head *queue;
1774 int idx;
1775
1776 idx = sched_find_first_bit(array->bitmap);
1777 BUG_ON(idx >= MAX_RT_PRIO);
1778
1779 queue = array->queue + idx;
1780 next = list_entry(queue->next, struct sched_rt_entity, run_list);
1781
1782 return next;
1783}
1784
1785static struct task_struct *_pick_next_task_rt(struct rq *rq)
1786{
1787 struct sched_rt_entity *rt_se;
1788 struct rt_rq *rt_rq = &rq->rt;
1789
1790 do {
1791 rt_se = pick_next_rt_entity(rt_rq);
1792 BUG_ON(!rt_se);
1793 rt_rq = group_rt_rq(rt_se);
1794 } while (rt_rq);
1795
1796 return rt_task_of(rt_se);
1797}
1798
1799static struct task_struct *pick_task_rt(struct rq *rq)
1800{
1801 struct task_struct *p;
1802
1803 if (!sched_rt_runnable(rq))
1804 return NULL;
1805
1806 p = _pick_next_task_rt(rq);
1807
1808 return p;
1809}
1810
1811static struct task_struct *pick_next_task_rt(struct rq *rq)
1812{
1813 struct task_struct *p = pick_task_rt(rq);
1814
1815 if (p)
1816 set_next_task_rt(rq, p, true);
1817
1818 return p;
1819}
1820
1821static void put_prev_task_rt(struct rq *rq, struct task_struct *p)
1822{
1823 struct sched_rt_entity *rt_se = &p->rt;
1824 struct rt_rq *rt_rq = &rq->rt;
1825
1826 if (on_rt_rq(&p->rt))
1827 update_stats_wait_start_rt(rt_rq, rt_se);
1828
1829 update_curr_rt(rq);
1830
1831 update_rt_rq_load_avg(rq_clock_pelt(rq), rq, 1);
1832
1833 /*
1834 * The previous task needs to be made eligible for pushing
1835 * if it is still active
1836 */
1837 if (on_rt_rq(&p->rt) && p->nr_cpus_allowed > 1)
1838 enqueue_pushable_task(rq, p);
1839}
1840
1841#ifdef CONFIG_SMP
1842
1843/* Only try algorithms three times */
1844#define RT_MAX_TRIES 3
1845
1846static int pick_rt_task(struct rq *rq, struct task_struct *p, int cpu)
1847{
1848 if (!task_on_cpu(rq, p) &&
1849 cpumask_test_cpu(cpu, &p->cpus_mask))
1850 return 1;
1851
1852 return 0;
1853}
1854
1855/*
1856 * Return the highest pushable rq's task, which is suitable to be executed
1857 * on the CPU, NULL otherwise
1858 */
1859static struct task_struct *pick_highest_pushable_task(struct rq *rq, int cpu)
1860{
1861 struct plist_head *head = &rq->rt.pushable_tasks;
1862 struct task_struct *p;
1863
1864 if (!has_pushable_tasks(rq))
1865 return NULL;
1866
1867 plist_for_each_entry(p, head, pushable_tasks) {
1868 if (pick_rt_task(rq, p, cpu))
1869 return p;
1870 }
1871
1872 return NULL;
1873}
1874
1875static DEFINE_PER_CPU(cpumask_var_t, local_cpu_mask);
1876
1877static int find_lowest_rq(struct task_struct *task)
1878{
1879 struct sched_domain *sd;
1880 struct cpumask *lowest_mask = this_cpu_cpumask_var_ptr(local_cpu_mask);
1881 int this_cpu = smp_processor_id();
1882 int cpu = task_cpu(task);
1883 int ret;
1884
1885 /* Make sure the mask is initialized first */
1886 if (unlikely(!lowest_mask))
1887 return -1;
1888
1889 if (task->nr_cpus_allowed == 1)
1890 return -1; /* No other targets possible */
1891
1892 /*
1893 * If we're on asym system ensure we consider the different capacities
1894 * of the CPUs when searching for the lowest_mask.
1895 */
1896 if (sched_asym_cpucap_active()) {
1897
1898 ret = cpupri_find_fitness(&task_rq(task)->rd->cpupri,
1899 task, lowest_mask,
1900 rt_task_fits_capacity);
1901 } else {
1902
1903 ret = cpupri_find(&task_rq(task)->rd->cpupri,
1904 task, lowest_mask);
1905 }
1906
1907 if (!ret)
1908 return -1; /* No targets found */
1909
1910 /*
1911 * At this point we have built a mask of CPUs representing the
1912 * lowest priority tasks in the system. Now we want to elect
1913 * the best one based on our affinity and topology.
1914 *
1915 * We prioritize the last CPU that the task executed on since
1916 * it is most likely cache-hot in that location.
1917 */
1918 if (cpumask_test_cpu(cpu, lowest_mask))
1919 return cpu;
1920
1921 /*
1922 * Otherwise, we consult the sched_domains span maps to figure
1923 * out which CPU is logically closest to our hot cache data.
1924 */
1925 if (!cpumask_test_cpu(this_cpu, lowest_mask))
1926 this_cpu = -1; /* Skip this_cpu opt if not among lowest */
1927
1928 rcu_read_lock();
1929 for_each_domain(cpu, sd) {
1930 if (sd->flags & SD_WAKE_AFFINE) {
1931 int best_cpu;
1932
1933 /*
1934 * "this_cpu" is cheaper to preempt than a
1935 * remote processor.
1936 */
1937 if (this_cpu != -1 &&
1938 cpumask_test_cpu(this_cpu, sched_domain_span(sd))) {
1939 rcu_read_unlock();
1940 return this_cpu;
1941 }
1942
1943 best_cpu = cpumask_any_and_distribute(lowest_mask,
1944 sched_domain_span(sd));
1945 if (best_cpu < nr_cpu_ids) {
1946 rcu_read_unlock();
1947 return best_cpu;
1948 }
1949 }
1950 }
1951 rcu_read_unlock();
1952
1953 /*
1954 * And finally, if there were no matches within the domains
1955 * just give the caller *something* to work with from the compatible
1956 * locations.
1957 */
1958 if (this_cpu != -1)
1959 return this_cpu;
1960
1961 cpu = cpumask_any_distribute(lowest_mask);
1962 if (cpu < nr_cpu_ids)
1963 return cpu;
1964
1965 return -1;
1966}
1967
1968/* Will lock the rq it finds */
1969static struct rq *find_lock_lowest_rq(struct task_struct *task, struct rq *rq)
1970{
1971 struct rq *lowest_rq = NULL;
1972 int tries;
1973 int cpu;
1974
1975 for (tries = 0; tries < RT_MAX_TRIES; tries++) {
1976 cpu = find_lowest_rq(task);
1977
1978 if ((cpu == -1) || (cpu == rq->cpu))
1979 break;
1980
1981 lowest_rq = cpu_rq(cpu);
1982
1983 if (lowest_rq->rt.highest_prio.curr <= task->prio) {
1984 /*
1985 * Target rq has tasks of equal or higher priority,
1986 * retrying does not release any lock and is unlikely
1987 * to yield a different result.
1988 */
1989 lowest_rq = NULL;
1990 break;
1991 }
1992
1993 /* if the prio of this runqueue changed, try again */
1994 if (double_lock_balance(rq, lowest_rq)) {
1995 /*
1996 * We had to unlock the run queue. In
1997 * the mean time, task could have
1998 * migrated already or had its affinity changed.
1999 * Also make sure that it wasn't scheduled on its rq.
2000 */
2001 if (unlikely(task_rq(task) != rq ||
2002 !cpumask_test_cpu(lowest_rq->cpu, &task->cpus_mask) ||
2003 task_on_cpu(rq, task) ||
2004 !rt_task(task) ||
2005 !task_on_rq_queued(task))) {
2006
2007 double_unlock_balance(rq, lowest_rq);
2008 lowest_rq = NULL;
2009 break;
2010 }
2011 }
2012
2013 /* If this rq is still suitable use it. */
2014 if (lowest_rq->rt.highest_prio.curr > task->prio)
2015 break;
2016
2017 /* try again */
2018 double_unlock_balance(rq, lowest_rq);
2019 lowest_rq = NULL;
2020 }
2021
2022 return lowest_rq;
2023}
2024
2025static struct task_struct *pick_next_pushable_task(struct rq *rq)
2026{
2027 struct task_struct *p;
2028
2029 if (!has_pushable_tasks(rq))
2030 return NULL;
2031
2032 p = plist_first_entry(&rq->rt.pushable_tasks,
2033 struct task_struct, pushable_tasks);
2034
2035 BUG_ON(rq->cpu != task_cpu(p));
2036 BUG_ON(task_current(rq, p));
2037 BUG_ON(p->nr_cpus_allowed <= 1);
2038
2039 BUG_ON(!task_on_rq_queued(p));
2040 BUG_ON(!rt_task(p));
2041
2042 return p;
2043}
2044
2045/*
2046 * If the current CPU has more than one RT task, see if the non
2047 * running task can migrate over to a CPU that is running a task
2048 * of lesser priority.
2049 */
2050static int push_rt_task(struct rq *rq, bool pull)
2051{
2052 struct task_struct *next_task;
2053 struct rq *lowest_rq;
2054 int ret = 0;
2055
2056 if (!rq->rt.overloaded)
2057 return 0;
2058
2059 next_task = pick_next_pushable_task(rq);
2060 if (!next_task)
2061 return 0;
2062
2063retry:
2064 /*
2065 * It's possible that the next_task slipped in of
2066 * higher priority than current. If that's the case
2067 * just reschedule current.
2068 */
2069 if (unlikely(next_task->prio < rq->curr->prio)) {
2070 resched_curr(rq);
2071 return 0;
2072 }
2073
2074 if (is_migration_disabled(next_task)) {
2075 struct task_struct *push_task = NULL;
2076 int cpu;
2077
2078 if (!pull || rq->push_busy)
2079 return 0;
2080
2081 /*
2082 * Invoking find_lowest_rq() on anything but an RT task doesn't
2083 * make sense. Per the above priority check, curr has to
2084 * be of higher priority than next_task, so no need to
2085 * reschedule when bailing out.
2086 *
2087 * Note that the stoppers are masqueraded as SCHED_FIFO
2088 * (cf. sched_set_stop_task()), so we can't rely on rt_task().
2089 */
2090 if (rq->curr->sched_class != &rt_sched_class)
2091 return 0;
2092
2093 cpu = find_lowest_rq(rq->curr);
2094 if (cpu == -1 || cpu == rq->cpu)
2095 return 0;
2096
2097 /*
2098 * Given we found a CPU with lower priority than @next_task,
2099 * therefore it should be running. However we cannot migrate it
2100 * to this other CPU, instead attempt to push the current
2101 * running task on this CPU away.
2102 */
2103 push_task = get_push_task(rq);
2104 if (push_task) {
2105 raw_spin_rq_unlock(rq);
2106 stop_one_cpu_nowait(rq->cpu, push_cpu_stop,
2107 push_task, &rq->push_work);
2108 raw_spin_rq_lock(rq);
2109 }
2110
2111 return 0;
2112 }
2113
2114 if (WARN_ON(next_task == rq->curr))
2115 return 0;
2116
2117 /* We might release rq lock */
2118 get_task_struct(next_task);
2119
2120 /* find_lock_lowest_rq locks the rq if found */
2121 lowest_rq = find_lock_lowest_rq(next_task, rq);
2122 if (!lowest_rq) {
2123 struct task_struct *task;
2124 /*
2125 * find_lock_lowest_rq releases rq->lock
2126 * so it is possible that next_task has migrated.
2127 *
2128 * We need to make sure that the task is still on the same
2129 * run-queue and is also still the next task eligible for
2130 * pushing.
2131 */
2132 task = pick_next_pushable_task(rq);
2133 if (task == next_task) {
2134 /*
2135 * The task hasn't migrated, and is still the next
2136 * eligible task, but we failed to find a run-queue
2137 * to push it to. Do not retry in this case, since
2138 * other CPUs will pull from us when ready.
2139 */
2140 goto out;
2141 }
2142
2143 if (!task)
2144 /* No more tasks, just exit */
2145 goto out;
2146
2147 /*
2148 * Something has shifted, try again.
2149 */
2150 put_task_struct(next_task);
2151 next_task = task;
2152 goto retry;
2153 }
2154
2155 deactivate_task(rq, next_task, 0);
2156 set_task_cpu(next_task, lowest_rq->cpu);
2157 activate_task(lowest_rq, next_task, 0);
2158 resched_curr(lowest_rq);
2159 ret = 1;
2160
2161 double_unlock_balance(rq, lowest_rq);
2162out:
2163 put_task_struct(next_task);
2164
2165 return ret;
2166}
2167
2168static void push_rt_tasks(struct rq *rq)
2169{
2170 /* push_rt_task will return true if it moved an RT */
2171 while (push_rt_task(rq, false))
2172 ;
2173}
2174
2175#ifdef HAVE_RT_PUSH_IPI
2176
2177/*
2178 * When a high priority task schedules out from a CPU and a lower priority
2179 * task is scheduled in, a check is made to see if there's any RT tasks
2180 * on other CPUs that are waiting to run because a higher priority RT task
2181 * is currently running on its CPU. In this case, the CPU with multiple RT
2182 * tasks queued on it (overloaded) needs to be notified that a CPU has opened
2183 * up that may be able to run one of its non-running queued RT tasks.
2184 *
2185 * All CPUs with overloaded RT tasks need to be notified as there is currently
2186 * no way to know which of these CPUs have the highest priority task waiting
2187 * to run. Instead of trying to take a spinlock on each of these CPUs,
2188 * which has shown to cause large latency when done on machines with many
2189 * CPUs, sending an IPI to the CPUs to have them push off the overloaded
2190 * RT tasks waiting to run.
2191 *
2192 * Just sending an IPI to each of the CPUs is also an issue, as on large
2193 * count CPU machines, this can cause an IPI storm on a CPU, especially
2194 * if its the only CPU with multiple RT tasks queued, and a large number
2195 * of CPUs scheduling a lower priority task at the same time.
2196 *
2197 * Each root domain has its own irq work function that can iterate over
2198 * all CPUs with RT overloaded tasks. Since all CPUs with overloaded RT
2199 * task must be checked if there's one or many CPUs that are lowering
2200 * their priority, there's a single irq work iterator that will try to
2201 * push off RT tasks that are waiting to run.
2202 *
2203 * When a CPU schedules a lower priority task, it will kick off the
2204 * irq work iterator that will jump to each CPU with overloaded RT tasks.
2205 * As it only takes the first CPU that schedules a lower priority task
2206 * to start the process, the rto_start variable is incremented and if
2207 * the atomic result is one, then that CPU will try to take the rto_lock.
2208 * This prevents high contention on the lock as the process handles all
2209 * CPUs scheduling lower priority tasks.
2210 *
2211 * All CPUs that are scheduling a lower priority task will increment the
2212 * rt_loop_next variable. This will make sure that the irq work iterator
2213 * checks all RT overloaded CPUs whenever a CPU schedules a new lower
2214 * priority task, even if the iterator is in the middle of a scan. Incrementing
2215 * the rt_loop_next will cause the iterator to perform another scan.
2216 *
2217 */
2218static int rto_next_cpu(struct root_domain *rd)
2219{
2220 int next;
2221 int cpu;
2222
2223 /*
2224 * When starting the IPI RT pushing, the rto_cpu is set to -1,
2225 * rt_next_cpu() will simply return the first CPU found in
2226 * the rto_mask.
2227 *
2228 * If rto_next_cpu() is called with rto_cpu is a valid CPU, it
2229 * will return the next CPU found in the rto_mask.
2230 *
2231 * If there are no more CPUs left in the rto_mask, then a check is made
2232 * against rto_loop and rto_loop_next. rto_loop is only updated with
2233 * the rto_lock held, but any CPU may increment the rto_loop_next
2234 * without any locking.
2235 */
2236 for (;;) {
2237
2238 /* When rto_cpu is -1 this acts like cpumask_first() */
2239 cpu = cpumask_next(rd->rto_cpu, rd->rto_mask);
2240
2241 rd->rto_cpu = cpu;
2242
2243 if (cpu < nr_cpu_ids)
2244 return cpu;
2245
2246 rd->rto_cpu = -1;
2247
2248 /*
2249 * ACQUIRE ensures we see the @rto_mask changes
2250 * made prior to the @next value observed.
2251 *
2252 * Matches WMB in rt_set_overload().
2253 */
2254 next = atomic_read_acquire(&rd->rto_loop_next);
2255
2256 if (rd->rto_loop == next)
2257 break;
2258
2259 rd->rto_loop = next;
2260 }
2261
2262 return -1;
2263}
2264
2265static inline bool rto_start_trylock(atomic_t *v)
2266{
2267 return !atomic_cmpxchg_acquire(v, 0, 1);
2268}
2269
2270static inline void rto_start_unlock(atomic_t *v)
2271{
2272 atomic_set_release(v, 0);
2273}
2274
2275static void tell_cpu_to_push(struct rq *rq)
2276{
2277 int cpu = -1;
2278
2279 /* Keep the loop going if the IPI is currently active */
2280 atomic_inc(&rq->rd->rto_loop_next);
2281
2282 /* Only one CPU can initiate a loop at a time */
2283 if (!rto_start_trylock(&rq->rd->rto_loop_start))
2284 return;
2285
2286 raw_spin_lock(&rq->rd->rto_lock);
2287
2288 /*
2289 * The rto_cpu is updated under the lock, if it has a valid CPU
2290 * then the IPI is still running and will continue due to the
2291 * update to loop_next, and nothing needs to be done here.
2292 * Otherwise it is finishing up and an ipi needs to be sent.
2293 */
2294 if (rq->rd->rto_cpu < 0)
2295 cpu = rto_next_cpu(rq->rd);
2296
2297 raw_spin_unlock(&rq->rd->rto_lock);
2298
2299 rto_start_unlock(&rq->rd->rto_loop_start);
2300
2301 if (cpu >= 0) {
2302 /* Make sure the rd does not get freed while pushing */
2303 sched_get_rd(rq->rd);
2304 irq_work_queue_on(&rq->rd->rto_push_work, cpu);
2305 }
2306}
2307
2308/* Called from hardirq context */
2309void rto_push_irq_work_func(struct irq_work *work)
2310{
2311 struct root_domain *rd =
2312 container_of(work, struct root_domain, rto_push_work);
2313 struct rq *rq;
2314 int cpu;
2315
2316 rq = this_rq();
2317
2318 /*
2319 * We do not need to grab the lock to check for has_pushable_tasks.
2320 * When it gets updated, a check is made if a push is possible.
2321 */
2322 if (has_pushable_tasks(rq)) {
2323 raw_spin_rq_lock(rq);
2324 while (push_rt_task(rq, true))
2325 ;
2326 raw_spin_rq_unlock(rq);
2327 }
2328
2329 raw_spin_lock(&rd->rto_lock);
2330
2331 /* Pass the IPI to the next rt overloaded queue */
2332 cpu = rto_next_cpu(rd);
2333
2334 raw_spin_unlock(&rd->rto_lock);
2335
2336 if (cpu < 0) {
2337 sched_put_rd(rd);
2338 return;
2339 }
2340
2341 /* Try the next RT overloaded CPU */
2342 irq_work_queue_on(&rd->rto_push_work, cpu);
2343}
2344#endif /* HAVE_RT_PUSH_IPI */
2345
2346static void pull_rt_task(struct rq *this_rq)
2347{
2348 int this_cpu = this_rq->cpu, cpu;
2349 bool resched = false;
2350 struct task_struct *p, *push_task;
2351 struct rq *src_rq;
2352 int rt_overload_count = rt_overloaded(this_rq);
2353
2354 if (likely(!rt_overload_count))
2355 return;
2356
2357 /*
2358 * Match the barrier from rt_set_overloaded; this guarantees that if we
2359 * see overloaded we must also see the rto_mask bit.
2360 */
2361 smp_rmb();
2362
2363 /* If we are the only overloaded CPU do nothing */
2364 if (rt_overload_count == 1 &&
2365 cpumask_test_cpu(this_rq->cpu, this_rq->rd->rto_mask))
2366 return;
2367
2368#ifdef HAVE_RT_PUSH_IPI
2369 if (sched_feat(RT_PUSH_IPI)) {
2370 tell_cpu_to_push(this_rq);
2371 return;
2372 }
2373#endif
2374
2375 for_each_cpu(cpu, this_rq->rd->rto_mask) {
2376 if (this_cpu == cpu)
2377 continue;
2378
2379 src_rq = cpu_rq(cpu);
2380
2381 /*
2382 * Don't bother taking the src_rq->lock if the next highest
2383 * task is known to be lower-priority than our current task.
2384 * This may look racy, but if this value is about to go
2385 * logically higher, the src_rq will push this task away.
2386 * And if its going logically lower, we do not care
2387 */
2388 if (src_rq->rt.highest_prio.next >=
2389 this_rq->rt.highest_prio.curr)
2390 continue;
2391
2392 /*
2393 * We can potentially drop this_rq's lock in
2394 * double_lock_balance, and another CPU could
2395 * alter this_rq
2396 */
2397 push_task = NULL;
2398 double_lock_balance(this_rq, src_rq);
2399
2400 /*
2401 * We can pull only a task, which is pushable
2402 * on its rq, and no others.
2403 */
2404 p = pick_highest_pushable_task(src_rq, this_cpu);
2405
2406 /*
2407 * Do we have an RT task that preempts
2408 * the to-be-scheduled task?
2409 */
2410 if (p && (p->prio < this_rq->rt.highest_prio.curr)) {
2411 WARN_ON(p == src_rq->curr);
2412 WARN_ON(!task_on_rq_queued(p));
2413
2414 /*
2415 * There's a chance that p is higher in priority
2416 * than what's currently running on its CPU.
2417 * This is just that p is waking up and hasn't
2418 * had a chance to schedule. We only pull
2419 * p if it is lower in priority than the
2420 * current task on the run queue
2421 */
2422 if (p->prio < src_rq->curr->prio)
2423 goto skip;
2424
2425 if (is_migration_disabled(p)) {
2426 push_task = get_push_task(src_rq);
2427 } else {
2428 deactivate_task(src_rq, p, 0);
2429 set_task_cpu(p, this_cpu);
2430 activate_task(this_rq, p, 0);
2431 resched = true;
2432 }
2433 /*
2434 * We continue with the search, just in
2435 * case there's an even higher prio task
2436 * in another runqueue. (low likelihood
2437 * but possible)
2438 */
2439 }
2440skip:
2441 double_unlock_balance(this_rq, src_rq);
2442
2443 if (push_task) {
2444 raw_spin_rq_unlock(this_rq);
2445 stop_one_cpu_nowait(src_rq->cpu, push_cpu_stop,
2446 push_task, &src_rq->push_work);
2447 raw_spin_rq_lock(this_rq);
2448 }
2449 }
2450
2451 if (resched)
2452 resched_curr(this_rq);
2453}
2454
2455/*
2456 * If we are not running and we are not going to reschedule soon, we should
2457 * try to push tasks away now
2458 */
2459static void task_woken_rt(struct rq *rq, struct task_struct *p)
2460{
2461 bool need_to_push = !task_on_cpu(rq, p) &&
2462 !test_tsk_need_resched(rq->curr) &&
2463 p->nr_cpus_allowed > 1 &&
2464 (dl_task(rq->curr) || rt_task(rq->curr)) &&
2465 (rq->curr->nr_cpus_allowed < 2 ||
2466 rq->curr->prio <= p->prio);
2467
2468 if (need_to_push)
2469 push_rt_tasks(rq);
2470}
2471
2472/* Assumes rq->lock is held */
2473static void rq_online_rt(struct rq *rq)
2474{
2475 if (rq->rt.overloaded)
2476 rt_set_overload(rq);
2477
2478 __enable_runtime(rq);
2479
2480 cpupri_set(&rq->rd->cpupri, rq->cpu, rq->rt.highest_prio.curr);
2481}
2482
2483/* Assumes rq->lock is held */
2484static void rq_offline_rt(struct rq *rq)
2485{
2486 if (rq->rt.overloaded)
2487 rt_clear_overload(rq);
2488
2489 __disable_runtime(rq);
2490
2491 cpupri_set(&rq->rd->cpupri, rq->cpu, CPUPRI_INVALID);
2492}
2493
2494/*
2495 * When switch from the rt queue, we bring ourselves to a position
2496 * that we might want to pull RT tasks from other runqueues.
2497 */
2498static void switched_from_rt(struct rq *rq, struct task_struct *p)
2499{
2500 /*
2501 * If there are other RT tasks then we will reschedule
2502 * and the scheduling of the other RT tasks will handle
2503 * the balancing. But if we are the last RT task
2504 * we may need to handle the pulling of RT tasks
2505 * now.
2506 */
2507 if (!task_on_rq_queued(p) || rq->rt.rt_nr_running)
2508 return;
2509
2510 rt_queue_pull_task(rq);
2511}
2512
2513void __init init_sched_rt_class(void)
2514{
2515 unsigned int i;
2516
2517 for_each_possible_cpu(i) {
2518 zalloc_cpumask_var_node(&per_cpu(local_cpu_mask, i),
2519 GFP_KERNEL, cpu_to_node(i));
2520 }
2521}
2522#endif /* CONFIG_SMP */
2523
2524/*
2525 * When switching a task to RT, we may overload the runqueue
2526 * with RT tasks. In this case we try to push them off to
2527 * other runqueues.
2528 */
2529static void switched_to_rt(struct rq *rq, struct task_struct *p)
2530{
2531 /*
2532 * If we are running, update the avg_rt tracking, as the running time
2533 * will now on be accounted into the latter.
2534 */
2535 if (task_current(rq, p)) {
2536 update_rt_rq_load_avg(rq_clock_pelt(rq), rq, 0);
2537 return;
2538 }
2539
2540 /*
2541 * If we are not running we may need to preempt the current
2542 * running task. If that current running task is also an RT task
2543 * then see if we can move to another run queue.
2544 */
2545 if (task_on_rq_queued(p)) {
2546#ifdef CONFIG_SMP
2547 if (p->nr_cpus_allowed > 1 && rq->rt.overloaded)
2548 rt_queue_push_tasks(rq);
2549#endif /* CONFIG_SMP */
2550 if (p->prio < rq->curr->prio && cpu_online(cpu_of(rq)))
2551 resched_curr(rq);
2552 }
2553}
2554
2555/*
2556 * Priority of the task has changed. This may cause
2557 * us to initiate a push or pull.
2558 */
2559static void
2560prio_changed_rt(struct rq *rq, struct task_struct *p, int oldprio)
2561{
2562 if (!task_on_rq_queued(p))
2563 return;
2564
2565 if (task_current(rq, p)) {
2566#ifdef CONFIG_SMP
2567 /*
2568 * If our priority decreases while running, we
2569 * may need to pull tasks to this runqueue.
2570 */
2571 if (oldprio < p->prio)
2572 rt_queue_pull_task(rq);
2573
2574 /*
2575 * If there's a higher priority task waiting to run
2576 * then reschedule.
2577 */
2578 if (p->prio > rq->rt.highest_prio.curr)
2579 resched_curr(rq);
2580#else
2581 /* For UP simply resched on drop of prio */
2582 if (oldprio < p->prio)
2583 resched_curr(rq);
2584#endif /* CONFIG_SMP */
2585 } else {
2586 /*
2587 * This task is not running, but if it is
2588 * greater than the current running task
2589 * then reschedule.
2590 */
2591 if (p->prio < rq->curr->prio)
2592 resched_curr(rq);
2593 }
2594}
2595
2596#ifdef CONFIG_POSIX_TIMERS
2597static void watchdog(struct rq *rq, struct task_struct *p)
2598{
2599 unsigned long soft, hard;
2600
2601 /* max may change after cur was read, this will be fixed next tick */
2602 soft = task_rlimit(p, RLIMIT_RTTIME);
2603 hard = task_rlimit_max(p, RLIMIT_RTTIME);
2604
2605 if (soft != RLIM_INFINITY) {
2606 unsigned long next;
2607
2608 if (p->rt.watchdog_stamp != jiffies) {
2609 p->rt.timeout++;
2610 p->rt.watchdog_stamp = jiffies;
2611 }
2612
2613 next = DIV_ROUND_UP(min(soft, hard), USEC_PER_SEC/HZ);
2614 if (p->rt.timeout > next) {
2615 posix_cputimers_rt_watchdog(&p->posix_cputimers,
2616 p->se.sum_exec_runtime);
2617 }
2618 }
2619}
2620#else
2621static inline void watchdog(struct rq *rq, struct task_struct *p) { }
2622#endif
2623
2624/*
2625 * scheduler tick hitting a task of our scheduling class.
2626 *
2627 * NOTE: This function can be called remotely by the tick offload that
2628 * goes along full dynticks. Therefore no local assumption can be made
2629 * and everything must be accessed through the @rq and @curr passed in
2630 * parameters.
2631 */
2632static void task_tick_rt(struct rq *rq, struct task_struct *p, int queued)
2633{
2634 struct sched_rt_entity *rt_se = &p->rt;
2635
2636 update_curr_rt(rq);
2637 update_rt_rq_load_avg(rq_clock_pelt(rq), rq, 1);
2638
2639 watchdog(rq, p);
2640
2641 /*
2642 * RR tasks need a special form of timeslice management.
2643 * FIFO tasks have no timeslices.
2644 */
2645 if (p->policy != SCHED_RR)
2646 return;
2647
2648 if (--p->rt.time_slice)
2649 return;
2650
2651 p->rt.time_slice = sched_rr_timeslice;
2652
2653 /*
2654 * Requeue to the end of queue if we (and all of our ancestors) are not
2655 * the only element on the queue
2656 */
2657 for_each_sched_rt_entity(rt_se) {
2658 if (rt_se->run_list.prev != rt_se->run_list.next) {
2659 requeue_task_rt(rq, p, 0);
2660 resched_curr(rq);
2661 return;
2662 }
2663 }
2664}
2665
2666static unsigned int get_rr_interval_rt(struct rq *rq, struct task_struct *task)
2667{
2668 /*
2669 * Time slice is 0 for SCHED_FIFO tasks
2670 */
2671 if (task->policy == SCHED_RR)
2672 return sched_rr_timeslice;
2673 else
2674 return 0;
2675}
2676
2677DEFINE_SCHED_CLASS(rt) = {
2678
2679 .enqueue_task = enqueue_task_rt,
2680 .dequeue_task = dequeue_task_rt,
2681 .yield_task = yield_task_rt,
2682
2683 .check_preempt_curr = check_preempt_curr_rt,
2684
2685 .pick_next_task = pick_next_task_rt,
2686 .put_prev_task = put_prev_task_rt,
2687 .set_next_task = set_next_task_rt,
2688
2689#ifdef CONFIG_SMP
2690 .balance = balance_rt,
2691 .pick_task = pick_task_rt,
2692 .select_task_rq = select_task_rq_rt,
2693 .set_cpus_allowed = set_cpus_allowed_common,
2694 .rq_online = rq_online_rt,
2695 .rq_offline = rq_offline_rt,
2696 .task_woken = task_woken_rt,
2697 .switched_from = switched_from_rt,
2698 .find_lock_rq = find_lock_lowest_rq,
2699#endif
2700
2701 .task_tick = task_tick_rt,
2702
2703 .get_rr_interval = get_rr_interval_rt,
2704
2705 .prio_changed = prio_changed_rt,
2706 .switched_to = switched_to_rt,
2707
2708 .update_curr = update_curr_rt,
2709
2710#ifdef CONFIG_UCLAMP_TASK
2711 .uclamp_enabled = 1,
2712#endif
2713};
2714
2715#ifdef CONFIG_RT_GROUP_SCHED
2716/*
2717 * Ensure that the real time constraints are schedulable.
2718 */
2719static DEFINE_MUTEX(rt_constraints_mutex);
2720
2721static inline int tg_has_rt_tasks(struct task_group *tg)
2722{
2723 struct task_struct *task;
2724 struct css_task_iter it;
2725 int ret = 0;
2726
2727 /*
2728 * Autogroups do not have RT tasks; see autogroup_create().
2729 */
2730 if (task_group_is_autogroup(tg))
2731 return 0;
2732
2733 css_task_iter_start(&tg->css, 0, &it);
2734 while (!ret && (task = css_task_iter_next(&it)))
2735 ret |= rt_task(task);
2736 css_task_iter_end(&it);
2737
2738 return ret;
2739}
2740
2741struct rt_schedulable_data {
2742 struct task_group *tg;
2743 u64 rt_period;
2744 u64 rt_runtime;
2745};
2746
2747static int tg_rt_schedulable(struct task_group *tg, void *data)
2748{
2749 struct rt_schedulable_data *d = data;
2750 struct task_group *child;
2751 unsigned long total, sum = 0;
2752 u64 period, runtime;
2753
2754 period = ktime_to_ns(tg->rt_bandwidth.rt_period);
2755 runtime = tg->rt_bandwidth.rt_runtime;
2756
2757 if (tg == d->tg) {
2758 period = d->rt_period;
2759 runtime = d->rt_runtime;
2760 }
2761
2762 /*
2763 * Cannot have more runtime than the period.
2764 */
2765 if (runtime > period && runtime != RUNTIME_INF)
2766 return -EINVAL;
2767
2768 /*
2769 * Ensure we don't starve existing RT tasks if runtime turns zero.
2770 */
2771 if (rt_bandwidth_enabled() && !runtime &&
2772 tg->rt_bandwidth.rt_runtime && tg_has_rt_tasks(tg))
2773 return -EBUSY;
2774
2775 total = to_ratio(period, runtime);
2776
2777 /*
2778 * Nobody can have more than the global setting allows.
2779 */
2780 if (total > to_ratio(global_rt_period(), global_rt_runtime()))
2781 return -EINVAL;
2782
2783 /*
2784 * The sum of our children's runtime should not exceed our own.
2785 */
2786 list_for_each_entry_rcu(child, &tg->children, siblings) {
2787 period = ktime_to_ns(child->rt_bandwidth.rt_period);
2788 runtime = child->rt_bandwidth.rt_runtime;
2789
2790 if (child == d->tg) {
2791 period = d->rt_period;
2792 runtime = d->rt_runtime;
2793 }
2794
2795 sum += to_ratio(period, runtime);
2796 }
2797
2798 if (sum > total)
2799 return -EINVAL;
2800
2801 return 0;
2802}
2803
2804static int __rt_schedulable(struct task_group *tg, u64 period, u64 runtime)
2805{
2806 int ret;
2807
2808 struct rt_schedulable_data data = {
2809 .tg = tg,
2810 .rt_period = period,
2811 .rt_runtime = runtime,
2812 };
2813
2814 rcu_read_lock();
2815 ret = walk_tg_tree(tg_rt_schedulable, tg_nop, &data);
2816 rcu_read_unlock();
2817
2818 return ret;
2819}
2820
2821static int tg_set_rt_bandwidth(struct task_group *tg,
2822 u64 rt_period, u64 rt_runtime)
2823{
2824 int i, err = 0;
2825
2826 /*
2827 * Disallowing the root group RT runtime is BAD, it would disallow the
2828 * kernel creating (and or operating) RT threads.
2829 */
2830 if (tg == &root_task_group && rt_runtime == 0)
2831 return -EINVAL;
2832
2833 /* No period doesn't make any sense. */
2834 if (rt_period == 0)
2835 return -EINVAL;
2836
2837 /*
2838 * Bound quota to defend quota against overflow during bandwidth shift.
2839 */
2840 if (rt_runtime != RUNTIME_INF && rt_runtime > max_rt_runtime)
2841 return -EINVAL;
2842
2843 mutex_lock(&rt_constraints_mutex);
2844 err = __rt_schedulable(tg, rt_period, rt_runtime);
2845 if (err)
2846 goto unlock;
2847
2848 raw_spin_lock_irq(&tg->rt_bandwidth.rt_runtime_lock);
2849 tg->rt_bandwidth.rt_period = ns_to_ktime(rt_period);
2850 tg->rt_bandwidth.rt_runtime = rt_runtime;
2851
2852 for_each_possible_cpu(i) {
2853 struct rt_rq *rt_rq = tg->rt_rq[i];
2854
2855 raw_spin_lock(&rt_rq->rt_runtime_lock);
2856 rt_rq->rt_runtime = rt_runtime;
2857 raw_spin_unlock(&rt_rq->rt_runtime_lock);
2858 }
2859 raw_spin_unlock_irq(&tg->rt_bandwidth.rt_runtime_lock);
2860unlock:
2861 mutex_unlock(&rt_constraints_mutex);
2862
2863 return err;
2864}
2865
2866int sched_group_set_rt_runtime(struct task_group *tg, long rt_runtime_us)
2867{
2868 u64 rt_runtime, rt_period;
2869
2870 rt_period = ktime_to_ns(tg->rt_bandwidth.rt_period);
2871 rt_runtime = (u64)rt_runtime_us * NSEC_PER_USEC;
2872 if (rt_runtime_us < 0)
2873 rt_runtime = RUNTIME_INF;
2874 else if ((u64)rt_runtime_us > U64_MAX / NSEC_PER_USEC)
2875 return -EINVAL;
2876
2877 return tg_set_rt_bandwidth(tg, rt_period, rt_runtime);
2878}
2879
2880long sched_group_rt_runtime(struct task_group *tg)
2881{
2882 u64 rt_runtime_us;
2883
2884 if (tg->rt_bandwidth.rt_runtime == RUNTIME_INF)
2885 return -1;
2886
2887 rt_runtime_us = tg->rt_bandwidth.rt_runtime;
2888 do_div(rt_runtime_us, NSEC_PER_USEC);
2889 return rt_runtime_us;
2890}
2891
2892int sched_group_set_rt_period(struct task_group *tg, u64 rt_period_us)
2893{
2894 u64 rt_runtime, rt_period;
2895
2896 if (rt_period_us > U64_MAX / NSEC_PER_USEC)
2897 return -EINVAL;
2898
2899 rt_period = rt_period_us * NSEC_PER_USEC;
2900 rt_runtime = tg->rt_bandwidth.rt_runtime;
2901
2902 return tg_set_rt_bandwidth(tg, rt_period, rt_runtime);
2903}
2904
2905long sched_group_rt_period(struct task_group *tg)
2906{
2907 u64 rt_period_us;
2908
2909 rt_period_us = ktime_to_ns(tg->rt_bandwidth.rt_period);
2910 do_div(rt_period_us, NSEC_PER_USEC);
2911 return rt_period_us;
2912}
2913
2914#ifdef CONFIG_SYSCTL
2915static int sched_rt_global_constraints(void)
2916{
2917 int ret = 0;
2918
2919 mutex_lock(&rt_constraints_mutex);
2920 ret = __rt_schedulable(NULL, 0, 0);
2921 mutex_unlock(&rt_constraints_mutex);
2922
2923 return ret;
2924}
2925#endif /* CONFIG_SYSCTL */
2926
2927int sched_rt_can_attach(struct task_group *tg, struct task_struct *tsk)
2928{
2929 /* Don't accept realtime tasks when there is no way for them to run */
2930 if (rt_task(tsk) && tg->rt_bandwidth.rt_runtime == 0)
2931 return 0;
2932
2933 return 1;
2934}
2935
2936#else /* !CONFIG_RT_GROUP_SCHED */
2937
2938#ifdef CONFIG_SYSCTL
2939static int sched_rt_global_constraints(void)
2940{
2941 unsigned long flags;
2942 int i;
2943
2944 raw_spin_lock_irqsave(&def_rt_bandwidth.rt_runtime_lock, flags);
2945 for_each_possible_cpu(i) {
2946 struct rt_rq *rt_rq = &cpu_rq(i)->rt;
2947
2948 raw_spin_lock(&rt_rq->rt_runtime_lock);
2949 rt_rq->rt_runtime = global_rt_runtime();
2950 raw_spin_unlock(&rt_rq->rt_runtime_lock);
2951 }
2952 raw_spin_unlock_irqrestore(&def_rt_bandwidth.rt_runtime_lock, flags);
2953
2954 return 0;
2955}
2956#endif /* CONFIG_SYSCTL */
2957#endif /* CONFIG_RT_GROUP_SCHED */
2958
2959#ifdef CONFIG_SYSCTL
2960static int sched_rt_global_validate(void)
2961{
2962 if (sysctl_sched_rt_period <= 0)
2963 return -EINVAL;
2964
2965 if ((sysctl_sched_rt_runtime != RUNTIME_INF) &&
2966 ((sysctl_sched_rt_runtime > sysctl_sched_rt_period) ||
2967 ((u64)sysctl_sched_rt_runtime *
2968 NSEC_PER_USEC > max_rt_runtime)))
2969 return -EINVAL;
2970
2971 return 0;
2972}
2973
2974static void sched_rt_do_global(void)
2975{
2976 unsigned long flags;
2977
2978 raw_spin_lock_irqsave(&def_rt_bandwidth.rt_runtime_lock, flags);
2979 def_rt_bandwidth.rt_runtime = global_rt_runtime();
2980 def_rt_bandwidth.rt_period = ns_to_ktime(global_rt_period());
2981 raw_spin_unlock_irqrestore(&def_rt_bandwidth.rt_runtime_lock, flags);
2982}
2983
2984static int sched_rt_handler(struct ctl_table *table, int write, void *buffer,
2985 size_t *lenp, loff_t *ppos)
2986{
2987 int old_period, old_runtime;
2988 static DEFINE_MUTEX(mutex);
2989 int ret;
2990
2991 mutex_lock(&mutex);
2992 old_period = sysctl_sched_rt_period;
2993 old_runtime = sysctl_sched_rt_runtime;
2994
2995 ret = proc_dointvec(table, write, buffer, lenp, ppos);
2996
2997 if (!ret && write) {
2998 ret = sched_rt_global_validate();
2999 if (ret)
3000 goto undo;
3001
3002 ret = sched_dl_global_validate();
3003 if (ret)
3004 goto undo;
3005
3006 ret = sched_rt_global_constraints();
3007 if (ret)
3008 goto undo;
3009
3010 sched_rt_do_global();
3011 sched_dl_do_global();
3012 }
3013 if (0) {
3014undo:
3015 sysctl_sched_rt_period = old_period;
3016 sysctl_sched_rt_runtime = old_runtime;
3017 }
3018 mutex_unlock(&mutex);
3019
3020 return ret;
3021}
3022
3023static int sched_rr_handler(struct ctl_table *table, int write, void *buffer,
3024 size_t *lenp, loff_t *ppos)
3025{
3026 int ret;
3027 static DEFINE_MUTEX(mutex);
3028
3029 mutex_lock(&mutex);
3030 ret = proc_dointvec(table, write, buffer, lenp, ppos);
3031 /*
3032 * Make sure that internally we keep jiffies.
3033 * Also, writing zero resets the timeslice to default:
3034 */
3035 if (!ret && write) {
3036 sched_rr_timeslice =
3037 sysctl_sched_rr_timeslice <= 0 ? RR_TIMESLICE :
3038 msecs_to_jiffies(sysctl_sched_rr_timeslice);
3039 }
3040 mutex_unlock(&mutex);
3041
3042 return ret;
3043}
3044#endif /* CONFIG_SYSCTL */
3045
3046#ifdef CONFIG_SCHED_DEBUG
3047void print_rt_stats(struct seq_file *m, int cpu)
3048{
3049 rt_rq_iter_t iter;
3050 struct rt_rq *rt_rq;
3051
3052 rcu_read_lock();
3053 for_each_rt_rq(rt_rq, iter, cpu_rq(cpu))
3054 print_rt_rq(m, cpu, rt_rq);
3055 rcu_read_unlock();
3056}
3057#endif /* CONFIG_SCHED_DEBUG */
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#include <linux/irq_work.h>
10
11int sched_rr_timeslice = RR_TIMESLICE;
12
13static int do_sched_rt_period_timer(struct rt_bandwidth *rt_b, int overrun);
14
15struct rt_bandwidth def_rt_bandwidth;
16
17static enum hrtimer_restart sched_rt_period_timer(struct hrtimer *timer)
18{
19 struct rt_bandwidth *rt_b =
20 container_of(timer, struct rt_bandwidth, rt_period_timer);
21 int idle = 0;
22 int overrun;
23
24 raw_spin_lock(&rt_b->rt_runtime_lock);
25 for (;;) {
26 overrun = hrtimer_forward_now(timer, rt_b->rt_period);
27 if (!overrun)
28 break;
29
30 raw_spin_unlock(&rt_b->rt_runtime_lock);
31 idle = do_sched_rt_period_timer(rt_b, overrun);
32 raw_spin_lock(&rt_b->rt_runtime_lock);
33 }
34 if (idle)
35 rt_b->rt_period_active = 0;
36 raw_spin_unlock(&rt_b->rt_runtime_lock);
37
38 return idle ? HRTIMER_NORESTART : HRTIMER_RESTART;
39}
40
41void init_rt_bandwidth(struct rt_bandwidth *rt_b, u64 period, u64 runtime)
42{
43 rt_b->rt_period = ns_to_ktime(period);
44 rt_b->rt_runtime = runtime;
45
46 raw_spin_lock_init(&rt_b->rt_runtime_lock);
47
48 hrtimer_init(&rt_b->rt_period_timer,
49 CLOCK_MONOTONIC, HRTIMER_MODE_REL);
50 rt_b->rt_period_timer.function = sched_rt_period_timer;
51}
52
53static void start_rt_bandwidth(struct rt_bandwidth *rt_b)
54{
55 if (!rt_bandwidth_enabled() || rt_b->rt_runtime == RUNTIME_INF)
56 return;
57
58 raw_spin_lock(&rt_b->rt_runtime_lock);
59 if (!rt_b->rt_period_active) {
60 rt_b->rt_period_active = 1;
61 /*
62 * SCHED_DEADLINE updates the bandwidth, as a run away
63 * RT task with a DL task could hog a CPU. But DL does
64 * not reset the period. If a deadline task was running
65 * without an RT task running, it can cause RT tasks to
66 * throttle when they start up. Kick the timer right away
67 * to update the period.
68 */
69 hrtimer_forward_now(&rt_b->rt_period_timer, ns_to_ktime(0));
70 hrtimer_start_expires(&rt_b->rt_period_timer, HRTIMER_MODE_ABS_PINNED);
71 }
72 raw_spin_unlock(&rt_b->rt_runtime_lock);
73}
74
75#if defined(CONFIG_SMP) && defined(HAVE_RT_PUSH_IPI)
76static void push_irq_work_func(struct irq_work *work);
77#endif
78
79void init_rt_rq(struct rt_rq *rt_rq)
80{
81 struct rt_prio_array *array;
82 int i;
83
84 array = &rt_rq->active;
85 for (i = 0; i < MAX_RT_PRIO; i++) {
86 INIT_LIST_HEAD(array->queue + i);
87 __clear_bit(i, array->bitmap);
88 }
89 /* delimiter for bitsearch: */
90 __set_bit(MAX_RT_PRIO, array->bitmap);
91
92#if defined CONFIG_SMP
93 rt_rq->highest_prio.curr = MAX_RT_PRIO;
94 rt_rq->highest_prio.next = MAX_RT_PRIO;
95 rt_rq->rt_nr_migratory = 0;
96 rt_rq->overloaded = 0;
97 plist_head_init(&rt_rq->pushable_tasks);
98
99#ifdef HAVE_RT_PUSH_IPI
100 rt_rq->push_flags = 0;
101 rt_rq->push_cpu = nr_cpu_ids;
102 raw_spin_lock_init(&rt_rq->push_lock);
103 init_irq_work(&rt_rq->push_work, push_irq_work_func);
104#endif
105#endif /* CONFIG_SMP */
106 /* We start is dequeued state, because no RT tasks are queued */
107 rt_rq->rt_queued = 0;
108
109 rt_rq->rt_time = 0;
110 rt_rq->rt_throttled = 0;
111 rt_rq->rt_runtime = 0;
112 raw_spin_lock_init(&rt_rq->rt_runtime_lock);
113}
114
115#ifdef CONFIG_RT_GROUP_SCHED
116static void destroy_rt_bandwidth(struct rt_bandwidth *rt_b)
117{
118 hrtimer_cancel(&rt_b->rt_period_timer);
119}
120
121#define rt_entity_is_task(rt_se) (!(rt_se)->my_q)
122
123static inline struct task_struct *rt_task_of(struct sched_rt_entity *rt_se)
124{
125#ifdef CONFIG_SCHED_DEBUG
126 WARN_ON_ONCE(!rt_entity_is_task(rt_se));
127#endif
128 return container_of(rt_se, struct task_struct, rt);
129}
130
131static inline struct rq *rq_of_rt_rq(struct rt_rq *rt_rq)
132{
133 return rt_rq->rq;
134}
135
136static inline struct rt_rq *rt_rq_of_se(struct sched_rt_entity *rt_se)
137{
138 return rt_se->rt_rq;
139}
140
141static inline struct rq *rq_of_rt_se(struct sched_rt_entity *rt_se)
142{
143 struct rt_rq *rt_rq = rt_se->rt_rq;
144
145 return rt_rq->rq;
146}
147
148void free_rt_sched_group(struct task_group *tg)
149{
150 int i;
151
152 if (tg->rt_se)
153 destroy_rt_bandwidth(&tg->rt_bandwidth);
154
155 for_each_possible_cpu(i) {
156 if (tg->rt_rq)
157 kfree(tg->rt_rq[i]);
158 if (tg->rt_se)
159 kfree(tg->rt_se[i]);
160 }
161
162 kfree(tg->rt_rq);
163 kfree(tg->rt_se);
164}
165
166void init_tg_rt_entry(struct task_group *tg, struct rt_rq *rt_rq,
167 struct sched_rt_entity *rt_se, int cpu,
168 struct sched_rt_entity *parent)
169{
170 struct rq *rq = cpu_rq(cpu);
171
172 rt_rq->highest_prio.curr = MAX_RT_PRIO;
173 rt_rq->rt_nr_boosted = 0;
174 rt_rq->rq = rq;
175 rt_rq->tg = tg;
176
177 tg->rt_rq[cpu] = rt_rq;
178 tg->rt_se[cpu] = rt_se;
179
180 if (!rt_se)
181 return;
182
183 if (!parent)
184 rt_se->rt_rq = &rq->rt;
185 else
186 rt_se->rt_rq = parent->my_q;
187
188 rt_se->my_q = rt_rq;
189 rt_se->parent = parent;
190 INIT_LIST_HEAD(&rt_se->run_list);
191}
192
193int alloc_rt_sched_group(struct task_group *tg, struct task_group *parent)
194{
195 struct rt_rq *rt_rq;
196 struct sched_rt_entity *rt_se;
197 int i;
198
199 tg->rt_rq = kzalloc(sizeof(rt_rq) * nr_cpu_ids, GFP_KERNEL);
200 if (!tg->rt_rq)
201 goto err;
202 tg->rt_se = kzalloc(sizeof(rt_se) * nr_cpu_ids, GFP_KERNEL);
203 if (!tg->rt_se)
204 goto err;
205
206 init_rt_bandwidth(&tg->rt_bandwidth,
207 ktime_to_ns(def_rt_bandwidth.rt_period), 0);
208
209 for_each_possible_cpu(i) {
210 rt_rq = kzalloc_node(sizeof(struct rt_rq),
211 GFP_KERNEL, cpu_to_node(i));
212 if (!rt_rq)
213 goto err;
214
215 rt_se = kzalloc_node(sizeof(struct sched_rt_entity),
216 GFP_KERNEL, cpu_to_node(i));
217 if (!rt_se)
218 goto err_free_rq;
219
220 init_rt_rq(rt_rq);
221 rt_rq->rt_runtime = tg->rt_bandwidth.rt_runtime;
222 init_tg_rt_entry(tg, rt_rq, rt_se, i, parent->rt_se[i]);
223 }
224
225 return 1;
226
227err_free_rq:
228 kfree(rt_rq);
229err:
230 return 0;
231}
232
233#else /* CONFIG_RT_GROUP_SCHED */
234
235#define rt_entity_is_task(rt_se) (1)
236
237static inline struct task_struct *rt_task_of(struct sched_rt_entity *rt_se)
238{
239 return container_of(rt_se, struct task_struct, rt);
240}
241
242static inline struct rq *rq_of_rt_rq(struct rt_rq *rt_rq)
243{
244 return container_of(rt_rq, struct rq, rt);
245}
246
247static inline struct rq *rq_of_rt_se(struct sched_rt_entity *rt_se)
248{
249 struct task_struct *p = rt_task_of(rt_se);
250
251 return task_rq(p);
252}
253
254static inline struct rt_rq *rt_rq_of_se(struct sched_rt_entity *rt_se)
255{
256 struct rq *rq = rq_of_rt_se(rt_se);
257
258 return &rq->rt;
259}
260
261void free_rt_sched_group(struct task_group *tg) { }
262
263int alloc_rt_sched_group(struct task_group *tg, struct task_group *parent)
264{
265 return 1;
266}
267#endif /* CONFIG_RT_GROUP_SCHED */
268
269#ifdef CONFIG_SMP
270
271static void pull_rt_task(struct rq *this_rq);
272
273static inline bool need_pull_rt_task(struct rq *rq, struct task_struct *prev)
274{
275 /* Try to pull RT tasks here if we lower this rq's prio */
276 return rq->rt.highest_prio.curr > prev->prio;
277}
278
279static inline int rt_overloaded(struct rq *rq)
280{
281 return atomic_read(&rq->rd->rto_count);
282}
283
284static inline void rt_set_overload(struct rq *rq)
285{
286 if (!rq->online)
287 return;
288
289 cpumask_set_cpu(rq->cpu, rq->rd->rto_mask);
290 /*
291 * Make sure the mask is visible before we set
292 * the overload count. That is checked to determine
293 * if we should look at the mask. It would be a shame
294 * if we looked at the mask, but the mask was not
295 * updated yet.
296 *
297 * Matched by the barrier in pull_rt_task().
298 */
299 smp_wmb();
300 atomic_inc(&rq->rd->rto_count);
301}
302
303static inline void rt_clear_overload(struct rq *rq)
304{
305 if (!rq->online)
306 return;
307
308 /* the order here really doesn't matter */
309 atomic_dec(&rq->rd->rto_count);
310 cpumask_clear_cpu(rq->cpu, rq->rd->rto_mask);
311}
312
313static void update_rt_migration(struct rt_rq *rt_rq)
314{
315 if (rt_rq->rt_nr_migratory && rt_rq->rt_nr_total > 1) {
316 if (!rt_rq->overloaded) {
317 rt_set_overload(rq_of_rt_rq(rt_rq));
318 rt_rq->overloaded = 1;
319 }
320 } else if (rt_rq->overloaded) {
321 rt_clear_overload(rq_of_rt_rq(rt_rq));
322 rt_rq->overloaded = 0;
323 }
324}
325
326static void inc_rt_migration(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
327{
328 struct task_struct *p;
329
330 if (!rt_entity_is_task(rt_se))
331 return;
332
333 p = rt_task_of(rt_se);
334 rt_rq = &rq_of_rt_rq(rt_rq)->rt;
335
336 rt_rq->rt_nr_total++;
337 if (p->nr_cpus_allowed > 1)
338 rt_rq->rt_nr_migratory++;
339
340 update_rt_migration(rt_rq);
341}
342
343static void dec_rt_migration(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
344{
345 struct task_struct *p;
346
347 if (!rt_entity_is_task(rt_se))
348 return;
349
350 p = rt_task_of(rt_se);
351 rt_rq = &rq_of_rt_rq(rt_rq)->rt;
352
353 rt_rq->rt_nr_total--;
354 if (p->nr_cpus_allowed > 1)
355 rt_rq->rt_nr_migratory--;
356
357 update_rt_migration(rt_rq);
358}
359
360static inline int has_pushable_tasks(struct rq *rq)
361{
362 return !plist_head_empty(&rq->rt.pushable_tasks);
363}
364
365static DEFINE_PER_CPU(struct callback_head, rt_push_head);
366static DEFINE_PER_CPU(struct callback_head, rt_pull_head);
367
368static void push_rt_tasks(struct rq *);
369static void pull_rt_task(struct rq *);
370
371static inline void queue_push_tasks(struct rq *rq)
372{
373 if (!has_pushable_tasks(rq))
374 return;
375
376 queue_balance_callback(rq, &per_cpu(rt_push_head, rq->cpu), push_rt_tasks);
377}
378
379static inline void queue_pull_task(struct rq *rq)
380{
381 queue_balance_callback(rq, &per_cpu(rt_pull_head, rq->cpu), pull_rt_task);
382}
383
384static void enqueue_pushable_task(struct rq *rq, struct task_struct *p)
385{
386 plist_del(&p->pushable_tasks, &rq->rt.pushable_tasks);
387 plist_node_init(&p->pushable_tasks, p->prio);
388 plist_add(&p->pushable_tasks, &rq->rt.pushable_tasks);
389
390 /* Update the highest prio pushable task */
391 if (p->prio < rq->rt.highest_prio.next)
392 rq->rt.highest_prio.next = p->prio;
393}
394
395static void dequeue_pushable_task(struct rq *rq, struct task_struct *p)
396{
397 plist_del(&p->pushable_tasks, &rq->rt.pushable_tasks);
398
399 /* Update the new highest prio pushable task */
400 if (has_pushable_tasks(rq)) {
401 p = plist_first_entry(&rq->rt.pushable_tasks,
402 struct task_struct, pushable_tasks);
403 rq->rt.highest_prio.next = p->prio;
404 } else
405 rq->rt.highest_prio.next = MAX_RT_PRIO;
406}
407
408#else
409
410static inline void enqueue_pushable_task(struct rq *rq, struct task_struct *p)
411{
412}
413
414static inline void dequeue_pushable_task(struct rq *rq, struct task_struct *p)
415{
416}
417
418static inline
419void inc_rt_migration(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
420{
421}
422
423static inline
424void dec_rt_migration(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
425{
426}
427
428static inline bool need_pull_rt_task(struct rq *rq, struct task_struct *prev)
429{
430 return false;
431}
432
433static inline void pull_rt_task(struct rq *this_rq)
434{
435}
436
437static inline void queue_push_tasks(struct rq *rq)
438{
439}
440#endif /* CONFIG_SMP */
441
442static void enqueue_top_rt_rq(struct rt_rq *rt_rq);
443static void dequeue_top_rt_rq(struct rt_rq *rt_rq);
444
445static inline int on_rt_rq(struct sched_rt_entity *rt_se)
446{
447 return rt_se->on_rq;
448}
449
450#ifdef CONFIG_RT_GROUP_SCHED
451
452static inline u64 sched_rt_runtime(struct rt_rq *rt_rq)
453{
454 if (!rt_rq->tg)
455 return RUNTIME_INF;
456
457 return rt_rq->rt_runtime;
458}
459
460static inline u64 sched_rt_period(struct rt_rq *rt_rq)
461{
462 return ktime_to_ns(rt_rq->tg->rt_bandwidth.rt_period);
463}
464
465typedef struct task_group *rt_rq_iter_t;
466
467static inline struct task_group *next_task_group(struct task_group *tg)
468{
469 do {
470 tg = list_entry_rcu(tg->list.next,
471 typeof(struct task_group), list);
472 } while (&tg->list != &task_groups && task_group_is_autogroup(tg));
473
474 if (&tg->list == &task_groups)
475 tg = NULL;
476
477 return tg;
478}
479
480#define for_each_rt_rq(rt_rq, iter, rq) \
481 for (iter = container_of(&task_groups, typeof(*iter), list); \
482 (iter = next_task_group(iter)) && \
483 (rt_rq = iter->rt_rq[cpu_of(rq)]);)
484
485#define for_each_sched_rt_entity(rt_se) \
486 for (; rt_se; rt_se = rt_se->parent)
487
488static inline struct rt_rq *group_rt_rq(struct sched_rt_entity *rt_se)
489{
490 return rt_se->my_q;
491}
492
493static void enqueue_rt_entity(struct sched_rt_entity *rt_se, unsigned int flags);
494static void dequeue_rt_entity(struct sched_rt_entity *rt_se, unsigned int flags);
495
496static void sched_rt_rq_enqueue(struct rt_rq *rt_rq)
497{
498 struct task_struct *curr = rq_of_rt_rq(rt_rq)->curr;
499 struct rq *rq = rq_of_rt_rq(rt_rq);
500 struct sched_rt_entity *rt_se;
501
502 int cpu = cpu_of(rq);
503
504 rt_se = rt_rq->tg->rt_se[cpu];
505
506 if (rt_rq->rt_nr_running) {
507 if (!rt_se)
508 enqueue_top_rt_rq(rt_rq);
509 else if (!on_rt_rq(rt_se))
510 enqueue_rt_entity(rt_se, 0);
511
512 if (rt_rq->highest_prio.curr < curr->prio)
513 resched_curr(rq);
514 }
515}
516
517static void sched_rt_rq_dequeue(struct rt_rq *rt_rq)
518{
519 struct sched_rt_entity *rt_se;
520 int cpu = cpu_of(rq_of_rt_rq(rt_rq));
521
522 rt_se = rt_rq->tg->rt_se[cpu];
523
524 if (!rt_se)
525 dequeue_top_rt_rq(rt_rq);
526 else if (on_rt_rq(rt_se))
527 dequeue_rt_entity(rt_se, 0);
528}
529
530static inline int rt_rq_throttled(struct rt_rq *rt_rq)
531{
532 return rt_rq->rt_throttled && !rt_rq->rt_nr_boosted;
533}
534
535static int rt_se_boosted(struct sched_rt_entity *rt_se)
536{
537 struct rt_rq *rt_rq = group_rt_rq(rt_se);
538 struct task_struct *p;
539
540 if (rt_rq)
541 return !!rt_rq->rt_nr_boosted;
542
543 p = rt_task_of(rt_se);
544 return p->prio != p->normal_prio;
545}
546
547#ifdef CONFIG_SMP
548static inline const struct cpumask *sched_rt_period_mask(void)
549{
550 return this_rq()->rd->span;
551}
552#else
553static inline const struct cpumask *sched_rt_period_mask(void)
554{
555 return cpu_online_mask;
556}
557#endif
558
559static inline
560struct rt_rq *sched_rt_period_rt_rq(struct rt_bandwidth *rt_b, int cpu)
561{
562 return container_of(rt_b, struct task_group, rt_bandwidth)->rt_rq[cpu];
563}
564
565static inline struct rt_bandwidth *sched_rt_bandwidth(struct rt_rq *rt_rq)
566{
567 return &rt_rq->tg->rt_bandwidth;
568}
569
570#else /* !CONFIG_RT_GROUP_SCHED */
571
572static inline u64 sched_rt_runtime(struct rt_rq *rt_rq)
573{
574 return rt_rq->rt_runtime;
575}
576
577static inline u64 sched_rt_period(struct rt_rq *rt_rq)
578{
579 return ktime_to_ns(def_rt_bandwidth.rt_period);
580}
581
582typedef struct rt_rq *rt_rq_iter_t;
583
584#define for_each_rt_rq(rt_rq, iter, rq) \
585 for ((void) iter, rt_rq = &rq->rt; rt_rq; rt_rq = NULL)
586
587#define for_each_sched_rt_entity(rt_se) \
588 for (; rt_se; rt_se = NULL)
589
590static inline struct rt_rq *group_rt_rq(struct sched_rt_entity *rt_se)
591{
592 return NULL;
593}
594
595static inline void sched_rt_rq_enqueue(struct rt_rq *rt_rq)
596{
597 struct rq *rq = rq_of_rt_rq(rt_rq);
598
599 if (!rt_rq->rt_nr_running)
600 return;
601
602 enqueue_top_rt_rq(rt_rq);
603 resched_curr(rq);
604}
605
606static inline void sched_rt_rq_dequeue(struct rt_rq *rt_rq)
607{
608 dequeue_top_rt_rq(rt_rq);
609}
610
611static inline int rt_rq_throttled(struct rt_rq *rt_rq)
612{
613 return rt_rq->rt_throttled;
614}
615
616static inline const struct cpumask *sched_rt_period_mask(void)
617{
618 return cpu_online_mask;
619}
620
621static inline
622struct rt_rq *sched_rt_period_rt_rq(struct rt_bandwidth *rt_b, int cpu)
623{
624 return &cpu_rq(cpu)->rt;
625}
626
627static inline struct rt_bandwidth *sched_rt_bandwidth(struct rt_rq *rt_rq)
628{
629 return &def_rt_bandwidth;
630}
631
632#endif /* CONFIG_RT_GROUP_SCHED */
633
634bool sched_rt_bandwidth_account(struct rt_rq *rt_rq)
635{
636 struct rt_bandwidth *rt_b = sched_rt_bandwidth(rt_rq);
637
638 return (hrtimer_active(&rt_b->rt_period_timer) ||
639 rt_rq->rt_time < rt_b->rt_runtime);
640}
641
642#ifdef CONFIG_SMP
643/*
644 * We ran out of runtime, see if we can borrow some from our neighbours.
645 */
646static void do_balance_runtime(struct rt_rq *rt_rq)
647{
648 struct rt_bandwidth *rt_b = sched_rt_bandwidth(rt_rq);
649 struct root_domain *rd = rq_of_rt_rq(rt_rq)->rd;
650 int i, weight;
651 u64 rt_period;
652
653 weight = cpumask_weight(rd->span);
654
655 raw_spin_lock(&rt_b->rt_runtime_lock);
656 rt_period = ktime_to_ns(rt_b->rt_period);
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 if (iter == rt_rq)
662 continue;
663
664 raw_spin_lock(&iter->rt_runtime_lock);
665 /*
666 * Either all rqs have inf runtime and there's nothing to steal
667 * or __disable_runtime() below sets a specific rq to inf to
668 * indicate its been disabled and disalow stealing.
669 */
670 if (iter->rt_runtime == RUNTIME_INF)
671 goto next;
672
673 /*
674 * From runqueues with spare time, take 1/n part of their
675 * spare time, but no more than our period.
676 */
677 diff = iter->rt_runtime - iter->rt_time;
678 if (diff > 0) {
679 diff = div_u64((u64)diff, weight);
680 if (rt_rq->rt_runtime + diff > rt_period)
681 diff = rt_period - rt_rq->rt_runtime;
682 iter->rt_runtime -= diff;
683 rt_rq->rt_runtime += diff;
684 if (rt_rq->rt_runtime == rt_period) {
685 raw_spin_unlock(&iter->rt_runtime_lock);
686 break;
687 }
688 }
689next:
690 raw_spin_unlock(&iter->rt_runtime_lock);
691 }
692 raw_spin_unlock(&rt_b->rt_runtime_lock);
693}
694
695/*
696 * Ensure this RQ takes back all the runtime it lend to its neighbours.
697 */
698static void __disable_runtime(struct rq *rq)
699{
700 struct root_domain *rd = rq->rd;
701 rt_rq_iter_t iter;
702 struct rt_rq *rt_rq;
703
704 if (unlikely(!scheduler_running))
705 return;
706
707 for_each_rt_rq(rt_rq, iter, rq) {
708 struct rt_bandwidth *rt_b = sched_rt_bandwidth(rt_rq);
709 s64 want;
710 int i;
711
712 raw_spin_lock(&rt_b->rt_runtime_lock);
713 raw_spin_lock(&rt_rq->rt_runtime_lock);
714 /*
715 * Either we're all inf and nobody needs to borrow, or we're
716 * already disabled and thus have nothing to do, or we have
717 * exactly the right amount of runtime to take out.
718 */
719 if (rt_rq->rt_runtime == RUNTIME_INF ||
720 rt_rq->rt_runtime == rt_b->rt_runtime)
721 goto balanced;
722 raw_spin_unlock(&rt_rq->rt_runtime_lock);
723
724 /*
725 * Calculate the difference between what we started out with
726 * and what we current have, that's the amount of runtime
727 * we lend and now have to reclaim.
728 */
729 want = rt_b->rt_runtime - rt_rq->rt_runtime;
730
731 /*
732 * Greedy reclaim, take back as much as we can.
733 */
734 for_each_cpu(i, rd->span) {
735 struct rt_rq *iter = sched_rt_period_rt_rq(rt_b, i);
736 s64 diff;
737
738 /*
739 * Can't reclaim from ourselves or disabled runqueues.
740 */
741 if (iter == rt_rq || iter->rt_runtime == RUNTIME_INF)
742 continue;
743
744 raw_spin_lock(&iter->rt_runtime_lock);
745 if (want > 0) {
746 diff = min_t(s64, iter->rt_runtime, want);
747 iter->rt_runtime -= diff;
748 want -= diff;
749 } else {
750 iter->rt_runtime -= want;
751 want -= want;
752 }
753 raw_spin_unlock(&iter->rt_runtime_lock);
754
755 if (!want)
756 break;
757 }
758
759 raw_spin_lock(&rt_rq->rt_runtime_lock);
760 /*
761 * We cannot be left wanting - that would mean some runtime
762 * leaked out of the system.
763 */
764 BUG_ON(want);
765balanced:
766 /*
767 * Disable all the borrow logic by pretending we have inf
768 * runtime - in which case borrowing doesn't make sense.
769 */
770 rt_rq->rt_runtime = RUNTIME_INF;
771 rt_rq->rt_throttled = 0;
772 raw_spin_unlock(&rt_rq->rt_runtime_lock);
773 raw_spin_unlock(&rt_b->rt_runtime_lock);
774
775 /* Make rt_rq available for pick_next_task() */
776 sched_rt_rq_enqueue(rt_rq);
777 }
778}
779
780static void __enable_runtime(struct rq *rq)
781{
782 rt_rq_iter_t iter;
783 struct rt_rq *rt_rq;
784
785 if (unlikely(!scheduler_running))
786 return;
787
788 /*
789 * Reset each runqueue's bandwidth settings
790 */
791 for_each_rt_rq(rt_rq, iter, rq) {
792 struct rt_bandwidth *rt_b = sched_rt_bandwidth(rt_rq);
793
794 raw_spin_lock(&rt_b->rt_runtime_lock);
795 raw_spin_lock(&rt_rq->rt_runtime_lock);
796 rt_rq->rt_runtime = rt_b->rt_runtime;
797 rt_rq->rt_time = 0;
798 rt_rq->rt_throttled = 0;
799 raw_spin_unlock(&rt_rq->rt_runtime_lock);
800 raw_spin_unlock(&rt_b->rt_runtime_lock);
801 }
802}
803
804static void balance_runtime(struct rt_rq *rt_rq)
805{
806 if (!sched_feat(RT_RUNTIME_SHARE))
807 return;
808
809 if (rt_rq->rt_time > rt_rq->rt_runtime) {
810 raw_spin_unlock(&rt_rq->rt_runtime_lock);
811 do_balance_runtime(rt_rq);
812 raw_spin_lock(&rt_rq->rt_runtime_lock);
813 }
814}
815#else /* !CONFIG_SMP */
816static inline void balance_runtime(struct rt_rq *rt_rq) {}
817#endif /* CONFIG_SMP */
818
819static int do_sched_rt_period_timer(struct rt_bandwidth *rt_b, int overrun)
820{
821 int i, idle = 1, throttled = 0;
822 const struct cpumask *span;
823
824 span = sched_rt_period_mask();
825#ifdef CONFIG_RT_GROUP_SCHED
826 /*
827 * FIXME: isolated CPUs should really leave the root task group,
828 * whether they are isolcpus or were isolated via cpusets, lest
829 * the timer run on a CPU which does not service all runqueues,
830 * potentially leaving other CPUs indefinitely throttled. If
831 * isolation is really required, the user will turn the throttle
832 * off to kill the perturbations it causes anyway. Meanwhile,
833 * this maintains functionality for boot and/or troubleshooting.
834 */
835 if (rt_b == &root_task_group.rt_bandwidth)
836 span = cpu_online_mask;
837#endif
838 for_each_cpu(i, span) {
839 int enqueue = 0;
840 struct rt_rq *rt_rq = sched_rt_period_rt_rq(rt_b, i);
841 struct rq *rq = rq_of_rt_rq(rt_rq);
842
843 raw_spin_lock(&rq->lock);
844 if (rt_rq->rt_time) {
845 u64 runtime;
846
847 raw_spin_lock(&rt_rq->rt_runtime_lock);
848 if (rt_rq->rt_throttled)
849 balance_runtime(rt_rq);
850 runtime = rt_rq->rt_runtime;
851 rt_rq->rt_time -= min(rt_rq->rt_time, overrun*runtime);
852 if (rt_rq->rt_throttled && rt_rq->rt_time < runtime) {
853 rt_rq->rt_throttled = 0;
854 enqueue = 1;
855
856 /*
857 * When we're idle and a woken (rt) task is
858 * throttled check_preempt_curr() will set
859 * skip_update and the time between the wakeup
860 * and this unthrottle will get accounted as
861 * 'runtime'.
862 */
863 if (rt_rq->rt_nr_running && rq->curr == rq->idle)
864 rq_clock_skip_update(rq, false);
865 }
866 if (rt_rq->rt_time || rt_rq->rt_nr_running)
867 idle = 0;
868 raw_spin_unlock(&rt_rq->rt_runtime_lock);
869 } else if (rt_rq->rt_nr_running) {
870 idle = 0;
871 if (!rt_rq_throttled(rt_rq))
872 enqueue = 1;
873 }
874 if (rt_rq->rt_throttled)
875 throttled = 1;
876
877 if (enqueue)
878 sched_rt_rq_enqueue(rt_rq);
879 raw_spin_unlock(&rq->lock);
880 }
881
882 if (!throttled && (!rt_bandwidth_enabled() || rt_b->rt_runtime == RUNTIME_INF))
883 return 1;
884
885 return idle;
886}
887
888static inline int rt_se_prio(struct sched_rt_entity *rt_se)
889{
890#ifdef CONFIG_RT_GROUP_SCHED
891 struct rt_rq *rt_rq = group_rt_rq(rt_se);
892
893 if (rt_rq)
894 return rt_rq->highest_prio.curr;
895#endif
896
897 return rt_task_of(rt_se)->prio;
898}
899
900static int sched_rt_runtime_exceeded(struct rt_rq *rt_rq)
901{
902 u64 runtime = sched_rt_runtime(rt_rq);
903
904 if (rt_rq->rt_throttled)
905 return rt_rq_throttled(rt_rq);
906
907 if (runtime >= sched_rt_period(rt_rq))
908 return 0;
909
910 balance_runtime(rt_rq);
911 runtime = sched_rt_runtime(rt_rq);
912 if (runtime == RUNTIME_INF)
913 return 0;
914
915 if (rt_rq->rt_time > runtime) {
916 struct rt_bandwidth *rt_b = sched_rt_bandwidth(rt_rq);
917
918 /*
919 * Don't actually throttle groups that have no runtime assigned
920 * but accrue some time due to boosting.
921 */
922 if (likely(rt_b->rt_runtime)) {
923 rt_rq->rt_throttled = 1;
924 printk_deferred_once("sched: RT throttling activated\n");
925 } else {
926 /*
927 * In case we did anyway, make it go away,
928 * replenishment is a joke, since it will replenish us
929 * with exactly 0 ns.
930 */
931 rt_rq->rt_time = 0;
932 }
933
934 if (rt_rq_throttled(rt_rq)) {
935 sched_rt_rq_dequeue(rt_rq);
936 return 1;
937 }
938 }
939
940 return 0;
941}
942
943/*
944 * Update the current task's runtime statistics. Skip current tasks that
945 * are not in our scheduling class.
946 */
947static void update_curr_rt(struct rq *rq)
948{
949 struct task_struct *curr = rq->curr;
950 struct sched_rt_entity *rt_se = &curr->rt;
951 u64 delta_exec;
952
953 if (curr->sched_class != &rt_sched_class)
954 return;
955
956 /* Kick cpufreq (see the comment in linux/cpufreq.h). */
957 if (cpu_of(rq) == smp_processor_id())
958 cpufreq_trigger_update(rq_clock(rq));
959
960 delta_exec = rq_clock_task(rq) - curr->se.exec_start;
961 if (unlikely((s64)delta_exec <= 0))
962 return;
963
964 schedstat_set(curr->se.statistics.exec_max,
965 max(curr->se.statistics.exec_max, delta_exec));
966
967 curr->se.sum_exec_runtime += delta_exec;
968 account_group_exec_runtime(curr, delta_exec);
969
970 curr->se.exec_start = rq_clock_task(rq);
971 cpuacct_charge(curr, delta_exec);
972
973 sched_rt_avg_update(rq, delta_exec);
974
975 if (!rt_bandwidth_enabled())
976 return;
977
978 for_each_sched_rt_entity(rt_se) {
979 struct rt_rq *rt_rq = rt_rq_of_se(rt_se);
980
981 if (sched_rt_runtime(rt_rq) != RUNTIME_INF) {
982 raw_spin_lock(&rt_rq->rt_runtime_lock);
983 rt_rq->rt_time += delta_exec;
984 if (sched_rt_runtime_exceeded(rt_rq))
985 resched_curr(rq);
986 raw_spin_unlock(&rt_rq->rt_runtime_lock);
987 }
988 }
989}
990
991static void
992dequeue_top_rt_rq(struct rt_rq *rt_rq)
993{
994 struct rq *rq = rq_of_rt_rq(rt_rq);
995
996 BUG_ON(&rq->rt != rt_rq);
997
998 if (!rt_rq->rt_queued)
999 return;
1000
1001 BUG_ON(!rq->nr_running);
1002
1003 sub_nr_running(rq, rt_rq->rt_nr_running);
1004 rt_rq->rt_queued = 0;
1005}
1006
1007static void
1008enqueue_top_rt_rq(struct rt_rq *rt_rq)
1009{
1010 struct rq *rq = rq_of_rt_rq(rt_rq);
1011
1012 BUG_ON(&rq->rt != rt_rq);
1013
1014 if (rt_rq->rt_queued)
1015 return;
1016 if (rt_rq_throttled(rt_rq) || !rt_rq->rt_nr_running)
1017 return;
1018
1019 add_nr_running(rq, rt_rq->rt_nr_running);
1020 rt_rq->rt_queued = 1;
1021}
1022
1023#if defined CONFIG_SMP
1024
1025static void
1026inc_rt_prio_smp(struct rt_rq *rt_rq, int prio, int prev_prio)
1027{
1028 struct rq *rq = rq_of_rt_rq(rt_rq);
1029
1030#ifdef CONFIG_RT_GROUP_SCHED
1031 /*
1032 * Change rq's cpupri only if rt_rq is the top queue.
1033 */
1034 if (&rq->rt != rt_rq)
1035 return;
1036#endif
1037 if (rq->online && prio < prev_prio)
1038 cpupri_set(&rq->rd->cpupri, rq->cpu, prio);
1039}
1040
1041static void
1042dec_rt_prio_smp(struct rt_rq *rt_rq, int prio, int prev_prio)
1043{
1044 struct rq *rq = rq_of_rt_rq(rt_rq);
1045
1046#ifdef CONFIG_RT_GROUP_SCHED
1047 /*
1048 * Change rq's cpupri only if rt_rq is the top queue.
1049 */
1050 if (&rq->rt != rt_rq)
1051 return;
1052#endif
1053 if (rq->online && rt_rq->highest_prio.curr != prev_prio)
1054 cpupri_set(&rq->rd->cpupri, rq->cpu, rt_rq->highest_prio.curr);
1055}
1056
1057#else /* CONFIG_SMP */
1058
1059static inline
1060void inc_rt_prio_smp(struct rt_rq *rt_rq, int prio, int prev_prio) {}
1061static inline
1062void dec_rt_prio_smp(struct rt_rq *rt_rq, int prio, int prev_prio) {}
1063
1064#endif /* CONFIG_SMP */
1065
1066#if defined CONFIG_SMP || defined CONFIG_RT_GROUP_SCHED
1067static void
1068inc_rt_prio(struct rt_rq *rt_rq, int prio)
1069{
1070 int prev_prio = rt_rq->highest_prio.curr;
1071
1072 if (prio < prev_prio)
1073 rt_rq->highest_prio.curr = prio;
1074
1075 inc_rt_prio_smp(rt_rq, prio, prev_prio);
1076}
1077
1078static void
1079dec_rt_prio(struct rt_rq *rt_rq, int prio)
1080{
1081 int prev_prio = rt_rq->highest_prio.curr;
1082
1083 if (rt_rq->rt_nr_running) {
1084
1085 WARN_ON(prio < prev_prio);
1086
1087 /*
1088 * This may have been our highest task, and therefore
1089 * we may have some recomputation to do
1090 */
1091 if (prio == prev_prio) {
1092 struct rt_prio_array *array = &rt_rq->active;
1093
1094 rt_rq->highest_prio.curr =
1095 sched_find_first_bit(array->bitmap);
1096 }
1097
1098 } else
1099 rt_rq->highest_prio.curr = MAX_RT_PRIO;
1100
1101 dec_rt_prio_smp(rt_rq, prio, prev_prio);
1102}
1103
1104#else
1105
1106static inline void inc_rt_prio(struct rt_rq *rt_rq, int prio) {}
1107static inline void dec_rt_prio(struct rt_rq *rt_rq, int prio) {}
1108
1109#endif /* CONFIG_SMP || CONFIG_RT_GROUP_SCHED */
1110
1111#ifdef CONFIG_RT_GROUP_SCHED
1112
1113static void
1114inc_rt_group(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
1115{
1116 if (rt_se_boosted(rt_se))
1117 rt_rq->rt_nr_boosted++;
1118
1119 if (rt_rq->tg)
1120 start_rt_bandwidth(&rt_rq->tg->rt_bandwidth);
1121}
1122
1123static void
1124dec_rt_group(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
1125{
1126 if (rt_se_boosted(rt_se))
1127 rt_rq->rt_nr_boosted--;
1128
1129 WARN_ON(!rt_rq->rt_nr_running && rt_rq->rt_nr_boosted);
1130}
1131
1132#else /* CONFIG_RT_GROUP_SCHED */
1133
1134static void
1135inc_rt_group(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
1136{
1137 start_rt_bandwidth(&def_rt_bandwidth);
1138}
1139
1140static inline
1141void dec_rt_group(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq) {}
1142
1143#endif /* CONFIG_RT_GROUP_SCHED */
1144
1145static inline
1146unsigned int rt_se_nr_running(struct sched_rt_entity *rt_se)
1147{
1148 struct rt_rq *group_rq = group_rt_rq(rt_se);
1149
1150 if (group_rq)
1151 return group_rq->rt_nr_running;
1152 else
1153 return 1;
1154}
1155
1156static inline
1157unsigned int rt_se_rr_nr_running(struct sched_rt_entity *rt_se)
1158{
1159 struct rt_rq *group_rq = group_rt_rq(rt_se);
1160 struct task_struct *tsk;
1161
1162 if (group_rq)
1163 return group_rq->rr_nr_running;
1164
1165 tsk = rt_task_of(rt_se);
1166
1167 return (tsk->policy == SCHED_RR) ? 1 : 0;
1168}
1169
1170static inline
1171void inc_rt_tasks(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
1172{
1173 int prio = rt_se_prio(rt_se);
1174
1175 WARN_ON(!rt_prio(prio));
1176 rt_rq->rt_nr_running += rt_se_nr_running(rt_se);
1177 rt_rq->rr_nr_running += rt_se_rr_nr_running(rt_se);
1178
1179 inc_rt_prio(rt_rq, prio);
1180 inc_rt_migration(rt_se, rt_rq);
1181 inc_rt_group(rt_se, rt_rq);
1182}
1183
1184static inline
1185void dec_rt_tasks(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
1186{
1187 WARN_ON(!rt_prio(rt_se_prio(rt_se)));
1188 WARN_ON(!rt_rq->rt_nr_running);
1189 rt_rq->rt_nr_running -= rt_se_nr_running(rt_se);
1190 rt_rq->rr_nr_running -= rt_se_rr_nr_running(rt_se);
1191
1192 dec_rt_prio(rt_rq, rt_se_prio(rt_se));
1193 dec_rt_migration(rt_se, rt_rq);
1194 dec_rt_group(rt_se, rt_rq);
1195}
1196
1197/*
1198 * Change rt_se->run_list location unless SAVE && !MOVE
1199 *
1200 * assumes ENQUEUE/DEQUEUE flags match
1201 */
1202static inline bool move_entity(unsigned int flags)
1203{
1204 if ((flags & (DEQUEUE_SAVE | DEQUEUE_MOVE)) == DEQUEUE_SAVE)
1205 return false;
1206
1207 return true;
1208}
1209
1210static void __delist_rt_entity(struct sched_rt_entity *rt_se, struct rt_prio_array *array)
1211{
1212 list_del_init(&rt_se->run_list);
1213
1214 if (list_empty(array->queue + rt_se_prio(rt_se)))
1215 __clear_bit(rt_se_prio(rt_se), array->bitmap);
1216
1217 rt_se->on_list = 0;
1218}
1219
1220static void __enqueue_rt_entity(struct sched_rt_entity *rt_se, unsigned int flags)
1221{
1222 struct rt_rq *rt_rq = rt_rq_of_se(rt_se);
1223 struct rt_prio_array *array = &rt_rq->active;
1224 struct rt_rq *group_rq = group_rt_rq(rt_se);
1225 struct list_head *queue = array->queue + rt_se_prio(rt_se);
1226
1227 /*
1228 * Don't enqueue the group if its throttled, or when empty.
1229 * The latter is a consequence of the former when a child group
1230 * get throttled and the current group doesn't have any other
1231 * active members.
1232 */
1233 if (group_rq && (rt_rq_throttled(group_rq) || !group_rq->rt_nr_running)) {
1234 if (rt_se->on_list)
1235 __delist_rt_entity(rt_se, array);
1236 return;
1237 }
1238
1239 if (move_entity(flags)) {
1240 WARN_ON_ONCE(rt_se->on_list);
1241 if (flags & ENQUEUE_HEAD)
1242 list_add(&rt_se->run_list, queue);
1243 else
1244 list_add_tail(&rt_se->run_list, queue);
1245
1246 __set_bit(rt_se_prio(rt_se), array->bitmap);
1247 rt_se->on_list = 1;
1248 }
1249 rt_se->on_rq = 1;
1250
1251 inc_rt_tasks(rt_se, rt_rq);
1252}
1253
1254static void __dequeue_rt_entity(struct sched_rt_entity *rt_se, unsigned int flags)
1255{
1256 struct rt_rq *rt_rq = rt_rq_of_se(rt_se);
1257 struct rt_prio_array *array = &rt_rq->active;
1258
1259 if (move_entity(flags)) {
1260 WARN_ON_ONCE(!rt_se->on_list);
1261 __delist_rt_entity(rt_se, array);
1262 }
1263 rt_se->on_rq = 0;
1264
1265 dec_rt_tasks(rt_se, rt_rq);
1266}
1267
1268/*
1269 * Because the prio of an upper entry depends on the lower
1270 * entries, we must remove entries top - down.
1271 */
1272static void dequeue_rt_stack(struct sched_rt_entity *rt_se, unsigned int flags)
1273{
1274 struct sched_rt_entity *back = NULL;
1275
1276 for_each_sched_rt_entity(rt_se) {
1277 rt_se->back = back;
1278 back = rt_se;
1279 }
1280
1281 dequeue_top_rt_rq(rt_rq_of_se(back));
1282
1283 for (rt_se = back; rt_se; rt_se = rt_se->back) {
1284 if (on_rt_rq(rt_se))
1285 __dequeue_rt_entity(rt_se, flags);
1286 }
1287}
1288
1289static void enqueue_rt_entity(struct sched_rt_entity *rt_se, unsigned int flags)
1290{
1291 struct rq *rq = rq_of_rt_se(rt_se);
1292
1293 dequeue_rt_stack(rt_se, flags);
1294 for_each_sched_rt_entity(rt_se)
1295 __enqueue_rt_entity(rt_se, flags);
1296 enqueue_top_rt_rq(&rq->rt);
1297}
1298
1299static void dequeue_rt_entity(struct sched_rt_entity *rt_se, unsigned int flags)
1300{
1301 struct rq *rq = rq_of_rt_se(rt_se);
1302
1303 dequeue_rt_stack(rt_se, flags);
1304
1305 for_each_sched_rt_entity(rt_se) {
1306 struct rt_rq *rt_rq = group_rt_rq(rt_se);
1307
1308 if (rt_rq && rt_rq->rt_nr_running)
1309 __enqueue_rt_entity(rt_se, flags);
1310 }
1311 enqueue_top_rt_rq(&rq->rt);
1312}
1313
1314/*
1315 * Adding/removing a task to/from a priority array:
1316 */
1317static void
1318enqueue_task_rt(struct rq *rq, struct task_struct *p, int flags)
1319{
1320 struct sched_rt_entity *rt_se = &p->rt;
1321
1322 if (flags & ENQUEUE_WAKEUP)
1323 rt_se->timeout = 0;
1324
1325 enqueue_rt_entity(rt_se, flags);
1326
1327 if (!task_current(rq, p) && p->nr_cpus_allowed > 1)
1328 enqueue_pushable_task(rq, p);
1329}
1330
1331static void dequeue_task_rt(struct rq *rq, struct task_struct *p, int flags)
1332{
1333 struct sched_rt_entity *rt_se = &p->rt;
1334
1335 update_curr_rt(rq);
1336 dequeue_rt_entity(rt_se, flags);
1337
1338 dequeue_pushable_task(rq, p);
1339}
1340
1341/*
1342 * Put task to the head or the end of the run list without the overhead of
1343 * dequeue followed by enqueue.
1344 */
1345static void
1346requeue_rt_entity(struct rt_rq *rt_rq, struct sched_rt_entity *rt_se, int head)
1347{
1348 if (on_rt_rq(rt_se)) {
1349 struct rt_prio_array *array = &rt_rq->active;
1350 struct list_head *queue = array->queue + rt_se_prio(rt_se);
1351
1352 if (head)
1353 list_move(&rt_se->run_list, queue);
1354 else
1355 list_move_tail(&rt_se->run_list, queue);
1356 }
1357}
1358
1359static void requeue_task_rt(struct rq *rq, struct task_struct *p, int head)
1360{
1361 struct sched_rt_entity *rt_se = &p->rt;
1362 struct rt_rq *rt_rq;
1363
1364 for_each_sched_rt_entity(rt_se) {
1365 rt_rq = rt_rq_of_se(rt_se);
1366 requeue_rt_entity(rt_rq, rt_se, head);
1367 }
1368}
1369
1370static void yield_task_rt(struct rq *rq)
1371{
1372 requeue_task_rt(rq, rq->curr, 0);
1373}
1374
1375#ifdef CONFIG_SMP
1376static int find_lowest_rq(struct task_struct *task);
1377
1378static int
1379select_task_rq_rt(struct task_struct *p, int cpu, int sd_flag, int flags)
1380{
1381 struct task_struct *curr;
1382 struct rq *rq;
1383
1384 /* For anything but wake ups, just return the task_cpu */
1385 if (sd_flag != SD_BALANCE_WAKE && sd_flag != SD_BALANCE_FORK)
1386 goto out;
1387
1388 rq = cpu_rq(cpu);
1389
1390 rcu_read_lock();
1391 curr = READ_ONCE(rq->curr); /* unlocked access */
1392
1393 /*
1394 * If the current task on @p's runqueue is an RT task, then
1395 * try to see if we can wake this RT task up on another
1396 * runqueue. Otherwise simply start this RT task
1397 * on its current runqueue.
1398 *
1399 * We want to avoid overloading runqueues. If the woken
1400 * task is a higher priority, then it will stay on this CPU
1401 * and the lower prio task should be moved to another CPU.
1402 * Even though this will probably make the lower prio task
1403 * lose its cache, we do not want to bounce a higher task
1404 * around just because it gave up its CPU, perhaps for a
1405 * lock?
1406 *
1407 * For equal prio tasks, we just let the scheduler sort it out.
1408 *
1409 * Otherwise, just let it ride on the affined RQ and the
1410 * post-schedule router will push the preempted task away
1411 *
1412 * This test is optimistic, if we get it wrong the load-balancer
1413 * will have to sort it out.
1414 */
1415 if (curr && unlikely(rt_task(curr)) &&
1416 (curr->nr_cpus_allowed < 2 ||
1417 curr->prio <= p->prio)) {
1418 int target = find_lowest_rq(p);
1419
1420 /*
1421 * Don't bother moving it if the destination CPU is
1422 * not running a lower priority task.
1423 */
1424 if (target != -1 &&
1425 p->prio < cpu_rq(target)->rt.highest_prio.curr)
1426 cpu = target;
1427 }
1428 rcu_read_unlock();
1429
1430out:
1431 return cpu;
1432}
1433
1434static void check_preempt_equal_prio(struct rq *rq, struct task_struct *p)
1435{
1436 /*
1437 * Current can't be migrated, useless to reschedule,
1438 * let's hope p can move out.
1439 */
1440 if (rq->curr->nr_cpus_allowed == 1 ||
1441 !cpupri_find(&rq->rd->cpupri, rq->curr, NULL))
1442 return;
1443
1444 /*
1445 * p is migratable, so let's not schedule it and
1446 * see if it is pushed or pulled somewhere else.
1447 */
1448 if (p->nr_cpus_allowed != 1
1449 && cpupri_find(&rq->rd->cpupri, p, NULL))
1450 return;
1451
1452 /*
1453 * There appears to be other cpus that can accept
1454 * current and none to run 'p', so lets reschedule
1455 * to try and push current away:
1456 */
1457 requeue_task_rt(rq, p, 1);
1458 resched_curr(rq);
1459}
1460
1461#endif /* CONFIG_SMP */
1462
1463/*
1464 * Preempt the current task with a newly woken task if needed:
1465 */
1466static void check_preempt_curr_rt(struct rq *rq, struct task_struct *p, int flags)
1467{
1468 if (p->prio < rq->curr->prio) {
1469 resched_curr(rq);
1470 return;
1471 }
1472
1473#ifdef CONFIG_SMP
1474 /*
1475 * If:
1476 *
1477 * - the newly woken task is of equal priority to the current task
1478 * - the newly woken task is non-migratable while current is migratable
1479 * - current will be preempted on the next reschedule
1480 *
1481 * we should check to see if current can readily move to a different
1482 * cpu. If so, we will reschedule to allow the push logic to try
1483 * to move current somewhere else, making room for our non-migratable
1484 * task.
1485 */
1486 if (p->prio == rq->curr->prio && !test_tsk_need_resched(rq->curr))
1487 check_preempt_equal_prio(rq, p);
1488#endif
1489}
1490
1491static struct sched_rt_entity *pick_next_rt_entity(struct rq *rq,
1492 struct rt_rq *rt_rq)
1493{
1494 struct rt_prio_array *array = &rt_rq->active;
1495 struct sched_rt_entity *next = NULL;
1496 struct list_head *queue;
1497 int idx;
1498
1499 idx = sched_find_first_bit(array->bitmap);
1500 BUG_ON(idx >= MAX_RT_PRIO);
1501
1502 queue = array->queue + idx;
1503 next = list_entry(queue->next, struct sched_rt_entity, run_list);
1504
1505 return next;
1506}
1507
1508static struct task_struct *_pick_next_task_rt(struct rq *rq)
1509{
1510 struct sched_rt_entity *rt_se;
1511 struct task_struct *p;
1512 struct rt_rq *rt_rq = &rq->rt;
1513
1514 do {
1515 rt_se = pick_next_rt_entity(rq, rt_rq);
1516 BUG_ON(!rt_se);
1517 rt_rq = group_rt_rq(rt_se);
1518 } while (rt_rq);
1519
1520 p = rt_task_of(rt_se);
1521 p->se.exec_start = rq_clock_task(rq);
1522
1523 return p;
1524}
1525
1526static struct task_struct *
1527pick_next_task_rt(struct rq *rq, struct task_struct *prev)
1528{
1529 struct task_struct *p;
1530 struct rt_rq *rt_rq = &rq->rt;
1531
1532 if (need_pull_rt_task(rq, prev)) {
1533 /*
1534 * This is OK, because current is on_cpu, which avoids it being
1535 * picked for load-balance and preemption/IRQs are still
1536 * disabled avoiding further scheduler activity on it and we're
1537 * being very careful to re-start the picking loop.
1538 */
1539 lockdep_unpin_lock(&rq->lock);
1540 pull_rt_task(rq);
1541 lockdep_pin_lock(&rq->lock);
1542 /*
1543 * pull_rt_task() can drop (and re-acquire) rq->lock; this
1544 * means a dl or stop task can slip in, in which case we need
1545 * to re-start task selection.
1546 */
1547 if (unlikely((rq->stop && task_on_rq_queued(rq->stop)) ||
1548 rq->dl.dl_nr_running))
1549 return RETRY_TASK;
1550 }
1551
1552 /*
1553 * We may dequeue prev's rt_rq in put_prev_task().
1554 * So, we update time before rt_nr_running check.
1555 */
1556 if (prev->sched_class == &rt_sched_class)
1557 update_curr_rt(rq);
1558
1559 if (!rt_rq->rt_queued)
1560 return NULL;
1561
1562 put_prev_task(rq, prev);
1563
1564 p = _pick_next_task_rt(rq);
1565
1566 /* The running task is never eligible for pushing */
1567 dequeue_pushable_task(rq, p);
1568
1569 queue_push_tasks(rq);
1570
1571 return p;
1572}
1573
1574static void put_prev_task_rt(struct rq *rq, struct task_struct *p)
1575{
1576 update_curr_rt(rq);
1577
1578 /*
1579 * The previous task needs to be made eligible for pushing
1580 * if it is still active
1581 */
1582 if (on_rt_rq(&p->rt) && p->nr_cpus_allowed > 1)
1583 enqueue_pushable_task(rq, p);
1584}
1585
1586#ifdef CONFIG_SMP
1587
1588/* Only try algorithms three times */
1589#define RT_MAX_TRIES 3
1590
1591static int pick_rt_task(struct rq *rq, struct task_struct *p, int cpu)
1592{
1593 if (!task_running(rq, p) &&
1594 cpumask_test_cpu(cpu, tsk_cpus_allowed(p)))
1595 return 1;
1596 return 0;
1597}
1598
1599/*
1600 * Return the highest pushable rq's task, which is suitable to be executed
1601 * on the cpu, NULL otherwise
1602 */
1603static struct task_struct *pick_highest_pushable_task(struct rq *rq, int cpu)
1604{
1605 struct plist_head *head = &rq->rt.pushable_tasks;
1606 struct task_struct *p;
1607
1608 if (!has_pushable_tasks(rq))
1609 return NULL;
1610
1611 plist_for_each_entry(p, head, pushable_tasks) {
1612 if (pick_rt_task(rq, p, cpu))
1613 return p;
1614 }
1615
1616 return NULL;
1617}
1618
1619static DEFINE_PER_CPU(cpumask_var_t, local_cpu_mask);
1620
1621static int find_lowest_rq(struct task_struct *task)
1622{
1623 struct sched_domain *sd;
1624 struct cpumask *lowest_mask = this_cpu_cpumask_var_ptr(local_cpu_mask);
1625 int this_cpu = smp_processor_id();
1626 int cpu = task_cpu(task);
1627
1628 /* Make sure the mask is initialized first */
1629 if (unlikely(!lowest_mask))
1630 return -1;
1631
1632 if (task->nr_cpus_allowed == 1)
1633 return -1; /* No other targets possible */
1634
1635 if (!cpupri_find(&task_rq(task)->rd->cpupri, task, lowest_mask))
1636 return -1; /* No targets found */
1637
1638 /*
1639 * At this point we have built a mask of cpus representing the
1640 * lowest priority tasks in the system. Now we want to elect
1641 * the best one based on our affinity and topology.
1642 *
1643 * We prioritize the last cpu that the task executed on since
1644 * it is most likely cache-hot in that location.
1645 */
1646 if (cpumask_test_cpu(cpu, lowest_mask))
1647 return cpu;
1648
1649 /*
1650 * Otherwise, we consult the sched_domains span maps to figure
1651 * out which cpu is logically closest to our hot cache data.
1652 */
1653 if (!cpumask_test_cpu(this_cpu, lowest_mask))
1654 this_cpu = -1; /* Skip this_cpu opt if not among lowest */
1655
1656 rcu_read_lock();
1657 for_each_domain(cpu, sd) {
1658 if (sd->flags & SD_WAKE_AFFINE) {
1659 int best_cpu;
1660
1661 /*
1662 * "this_cpu" is cheaper to preempt than a
1663 * remote processor.
1664 */
1665 if (this_cpu != -1 &&
1666 cpumask_test_cpu(this_cpu, sched_domain_span(sd))) {
1667 rcu_read_unlock();
1668 return this_cpu;
1669 }
1670
1671 best_cpu = cpumask_first_and(lowest_mask,
1672 sched_domain_span(sd));
1673 if (best_cpu < nr_cpu_ids) {
1674 rcu_read_unlock();
1675 return best_cpu;
1676 }
1677 }
1678 }
1679 rcu_read_unlock();
1680
1681 /*
1682 * And finally, if there were no matches within the domains
1683 * just give the caller *something* to work with from the compatible
1684 * locations.
1685 */
1686 if (this_cpu != -1)
1687 return this_cpu;
1688
1689 cpu = cpumask_any(lowest_mask);
1690 if (cpu < nr_cpu_ids)
1691 return cpu;
1692 return -1;
1693}
1694
1695/* Will lock the rq it finds */
1696static struct rq *find_lock_lowest_rq(struct task_struct *task, struct rq *rq)
1697{
1698 struct rq *lowest_rq = NULL;
1699 int tries;
1700 int cpu;
1701
1702 for (tries = 0; tries < RT_MAX_TRIES; tries++) {
1703 cpu = find_lowest_rq(task);
1704
1705 if ((cpu == -1) || (cpu == rq->cpu))
1706 break;
1707
1708 lowest_rq = cpu_rq(cpu);
1709
1710 if (lowest_rq->rt.highest_prio.curr <= task->prio) {
1711 /*
1712 * Target rq has tasks of equal or higher priority,
1713 * retrying does not release any lock and is unlikely
1714 * to yield a different result.
1715 */
1716 lowest_rq = NULL;
1717 break;
1718 }
1719
1720 /* if the prio of this runqueue changed, try again */
1721 if (double_lock_balance(rq, lowest_rq)) {
1722 /*
1723 * We had to unlock the run queue. In
1724 * the mean time, task could have
1725 * migrated already or had its affinity changed.
1726 * Also make sure that it wasn't scheduled on its rq.
1727 */
1728 if (unlikely(task_rq(task) != rq ||
1729 !cpumask_test_cpu(lowest_rq->cpu,
1730 tsk_cpus_allowed(task)) ||
1731 task_running(rq, task) ||
1732 !rt_task(task) ||
1733 !task_on_rq_queued(task))) {
1734
1735 double_unlock_balance(rq, lowest_rq);
1736 lowest_rq = NULL;
1737 break;
1738 }
1739 }
1740
1741 /* If this rq is still suitable use it. */
1742 if (lowest_rq->rt.highest_prio.curr > task->prio)
1743 break;
1744
1745 /* try again */
1746 double_unlock_balance(rq, lowest_rq);
1747 lowest_rq = NULL;
1748 }
1749
1750 return lowest_rq;
1751}
1752
1753static struct task_struct *pick_next_pushable_task(struct rq *rq)
1754{
1755 struct task_struct *p;
1756
1757 if (!has_pushable_tasks(rq))
1758 return NULL;
1759
1760 p = plist_first_entry(&rq->rt.pushable_tasks,
1761 struct task_struct, pushable_tasks);
1762
1763 BUG_ON(rq->cpu != task_cpu(p));
1764 BUG_ON(task_current(rq, p));
1765 BUG_ON(p->nr_cpus_allowed <= 1);
1766
1767 BUG_ON(!task_on_rq_queued(p));
1768 BUG_ON(!rt_task(p));
1769
1770 return p;
1771}
1772
1773/*
1774 * If the current CPU has more than one RT task, see if the non
1775 * running task can migrate over to a CPU that is running a task
1776 * of lesser priority.
1777 */
1778static int push_rt_task(struct rq *rq)
1779{
1780 struct task_struct *next_task;
1781 struct rq *lowest_rq;
1782 int ret = 0;
1783
1784 if (!rq->rt.overloaded)
1785 return 0;
1786
1787 next_task = pick_next_pushable_task(rq);
1788 if (!next_task)
1789 return 0;
1790
1791retry:
1792 if (unlikely(next_task == rq->curr)) {
1793 WARN_ON(1);
1794 return 0;
1795 }
1796
1797 /*
1798 * It's possible that the next_task slipped in of
1799 * higher priority than current. If that's the case
1800 * just reschedule current.
1801 */
1802 if (unlikely(next_task->prio < rq->curr->prio)) {
1803 resched_curr(rq);
1804 return 0;
1805 }
1806
1807 /* We might release rq lock */
1808 get_task_struct(next_task);
1809
1810 /* find_lock_lowest_rq locks the rq if found */
1811 lowest_rq = find_lock_lowest_rq(next_task, rq);
1812 if (!lowest_rq) {
1813 struct task_struct *task;
1814 /*
1815 * find_lock_lowest_rq releases rq->lock
1816 * so it is possible that next_task has migrated.
1817 *
1818 * We need to make sure that the task is still on the same
1819 * run-queue and is also still the next task eligible for
1820 * pushing.
1821 */
1822 task = pick_next_pushable_task(rq);
1823 if (task_cpu(next_task) == rq->cpu && task == next_task) {
1824 /*
1825 * The task hasn't migrated, and is still the next
1826 * eligible task, but we failed to find a run-queue
1827 * to push it to. Do not retry in this case, since
1828 * other cpus will pull from us when ready.
1829 */
1830 goto out;
1831 }
1832
1833 if (!task)
1834 /* No more tasks, just exit */
1835 goto out;
1836
1837 /*
1838 * Something has shifted, try again.
1839 */
1840 put_task_struct(next_task);
1841 next_task = task;
1842 goto retry;
1843 }
1844
1845 deactivate_task(rq, next_task, 0);
1846 set_task_cpu(next_task, lowest_rq->cpu);
1847 activate_task(lowest_rq, next_task, 0);
1848 ret = 1;
1849
1850 resched_curr(lowest_rq);
1851
1852 double_unlock_balance(rq, lowest_rq);
1853
1854out:
1855 put_task_struct(next_task);
1856
1857 return ret;
1858}
1859
1860static void push_rt_tasks(struct rq *rq)
1861{
1862 /* push_rt_task will return true if it moved an RT */
1863 while (push_rt_task(rq))
1864 ;
1865}
1866
1867#ifdef HAVE_RT_PUSH_IPI
1868/*
1869 * The search for the next cpu always starts at rq->cpu and ends
1870 * when we reach rq->cpu again. It will never return rq->cpu.
1871 * This returns the next cpu to check, or nr_cpu_ids if the loop
1872 * is complete.
1873 *
1874 * rq->rt.push_cpu holds the last cpu returned by this function,
1875 * or if this is the first instance, it must hold rq->cpu.
1876 */
1877static int rto_next_cpu(struct rq *rq)
1878{
1879 int prev_cpu = rq->rt.push_cpu;
1880 int cpu;
1881
1882 cpu = cpumask_next(prev_cpu, rq->rd->rto_mask);
1883
1884 /*
1885 * If the previous cpu is less than the rq's CPU, then it already
1886 * passed the end of the mask, and has started from the beginning.
1887 * We end if the next CPU is greater or equal to rq's CPU.
1888 */
1889 if (prev_cpu < rq->cpu) {
1890 if (cpu >= rq->cpu)
1891 return nr_cpu_ids;
1892
1893 } else if (cpu >= nr_cpu_ids) {
1894 /*
1895 * We passed the end of the mask, start at the beginning.
1896 * If the result is greater or equal to the rq's CPU, then
1897 * the loop is finished.
1898 */
1899 cpu = cpumask_first(rq->rd->rto_mask);
1900 if (cpu >= rq->cpu)
1901 return nr_cpu_ids;
1902 }
1903 rq->rt.push_cpu = cpu;
1904
1905 /* Return cpu to let the caller know if the loop is finished or not */
1906 return cpu;
1907}
1908
1909static int find_next_push_cpu(struct rq *rq)
1910{
1911 struct rq *next_rq;
1912 int cpu;
1913
1914 while (1) {
1915 cpu = rto_next_cpu(rq);
1916 if (cpu >= nr_cpu_ids)
1917 break;
1918 next_rq = cpu_rq(cpu);
1919
1920 /* Make sure the next rq can push to this rq */
1921 if (next_rq->rt.highest_prio.next < rq->rt.highest_prio.curr)
1922 break;
1923 }
1924
1925 return cpu;
1926}
1927
1928#define RT_PUSH_IPI_EXECUTING 1
1929#define RT_PUSH_IPI_RESTART 2
1930
1931static void tell_cpu_to_push(struct rq *rq)
1932{
1933 int cpu;
1934
1935 if (rq->rt.push_flags & RT_PUSH_IPI_EXECUTING) {
1936 raw_spin_lock(&rq->rt.push_lock);
1937 /* Make sure it's still executing */
1938 if (rq->rt.push_flags & RT_PUSH_IPI_EXECUTING) {
1939 /*
1940 * Tell the IPI to restart the loop as things have
1941 * changed since it started.
1942 */
1943 rq->rt.push_flags |= RT_PUSH_IPI_RESTART;
1944 raw_spin_unlock(&rq->rt.push_lock);
1945 return;
1946 }
1947 raw_spin_unlock(&rq->rt.push_lock);
1948 }
1949
1950 /* When here, there's no IPI going around */
1951
1952 rq->rt.push_cpu = rq->cpu;
1953 cpu = find_next_push_cpu(rq);
1954 if (cpu >= nr_cpu_ids)
1955 return;
1956
1957 rq->rt.push_flags = RT_PUSH_IPI_EXECUTING;
1958
1959 irq_work_queue_on(&rq->rt.push_work, cpu);
1960}
1961
1962/* Called from hardirq context */
1963static void try_to_push_tasks(void *arg)
1964{
1965 struct rt_rq *rt_rq = arg;
1966 struct rq *rq, *src_rq;
1967 int this_cpu;
1968 int cpu;
1969
1970 this_cpu = rt_rq->push_cpu;
1971
1972 /* Paranoid check */
1973 BUG_ON(this_cpu != smp_processor_id());
1974
1975 rq = cpu_rq(this_cpu);
1976 src_rq = rq_of_rt_rq(rt_rq);
1977
1978again:
1979 if (has_pushable_tasks(rq)) {
1980 raw_spin_lock(&rq->lock);
1981 push_rt_task(rq);
1982 raw_spin_unlock(&rq->lock);
1983 }
1984
1985 /* Pass the IPI to the next rt overloaded queue */
1986 raw_spin_lock(&rt_rq->push_lock);
1987 /*
1988 * If the source queue changed since the IPI went out,
1989 * we need to restart the search from that CPU again.
1990 */
1991 if (rt_rq->push_flags & RT_PUSH_IPI_RESTART) {
1992 rt_rq->push_flags &= ~RT_PUSH_IPI_RESTART;
1993 rt_rq->push_cpu = src_rq->cpu;
1994 }
1995
1996 cpu = find_next_push_cpu(src_rq);
1997
1998 if (cpu >= nr_cpu_ids)
1999 rt_rq->push_flags &= ~RT_PUSH_IPI_EXECUTING;
2000 raw_spin_unlock(&rt_rq->push_lock);
2001
2002 if (cpu >= nr_cpu_ids)
2003 return;
2004
2005 /*
2006 * It is possible that a restart caused this CPU to be
2007 * chosen again. Don't bother with an IPI, just see if we
2008 * have more to push.
2009 */
2010 if (unlikely(cpu == rq->cpu))
2011 goto again;
2012
2013 /* Try the next RT overloaded CPU */
2014 irq_work_queue_on(&rt_rq->push_work, cpu);
2015}
2016
2017static void push_irq_work_func(struct irq_work *work)
2018{
2019 struct rt_rq *rt_rq = container_of(work, struct rt_rq, push_work);
2020
2021 try_to_push_tasks(rt_rq);
2022}
2023#endif /* HAVE_RT_PUSH_IPI */
2024
2025static void pull_rt_task(struct rq *this_rq)
2026{
2027 int this_cpu = this_rq->cpu, cpu;
2028 bool resched = false;
2029 struct task_struct *p;
2030 struct rq *src_rq;
2031
2032 if (likely(!rt_overloaded(this_rq)))
2033 return;
2034
2035 /*
2036 * Match the barrier from rt_set_overloaded; this guarantees that if we
2037 * see overloaded we must also see the rto_mask bit.
2038 */
2039 smp_rmb();
2040
2041#ifdef HAVE_RT_PUSH_IPI
2042 if (sched_feat(RT_PUSH_IPI)) {
2043 tell_cpu_to_push(this_rq);
2044 return;
2045 }
2046#endif
2047
2048 for_each_cpu(cpu, this_rq->rd->rto_mask) {
2049 if (this_cpu == cpu)
2050 continue;
2051
2052 src_rq = cpu_rq(cpu);
2053
2054 /*
2055 * Don't bother taking the src_rq->lock if the next highest
2056 * task is known to be lower-priority than our current task.
2057 * This may look racy, but if this value is about to go
2058 * logically higher, the src_rq will push this task away.
2059 * And if its going logically lower, we do not care
2060 */
2061 if (src_rq->rt.highest_prio.next >=
2062 this_rq->rt.highest_prio.curr)
2063 continue;
2064
2065 /*
2066 * We can potentially drop this_rq's lock in
2067 * double_lock_balance, and another CPU could
2068 * alter this_rq
2069 */
2070 double_lock_balance(this_rq, src_rq);
2071
2072 /*
2073 * We can pull only a task, which is pushable
2074 * on its rq, and no others.
2075 */
2076 p = pick_highest_pushable_task(src_rq, this_cpu);
2077
2078 /*
2079 * Do we have an RT task that preempts
2080 * the to-be-scheduled task?
2081 */
2082 if (p && (p->prio < this_rq->rt.highest_prio.curr)) {
2083 WARN_ON(p == src_rq->curr);
2084 WARN_ON(!task_on_rq_queued(p));
2085
2086 /*
2087 * There's a chance that p is higher in priority
2088 * than what's currently running on its cpu.
2089 * This is just that p is wakeing up and hasn't
2090 * had a chance to schedule. We only pull
2091 * p if it is lower in priority than the
2092 * current task on the run queue
2093 */
2094 if (p->prio < src_rq->curr->prio)
2095 goto skip;
2096
2097 resched = true;
2098
2099 deactivate_task(src_rq, p, 0);
2100 set_task_cpu(p, this_cpu);
2101 activate_task(this_rq, p, 0);
2102 /*
2103 * We continue with the search, just in
2104 * case there's an even higher prio task
2105 * in another runqueue. (low likelihood
2106 * but possible)
2107 */
2108 }
2109skip:
2110 double_unlock_balance(this_rq, src_rq);
2111 }
2112
2113 if (resched)
2114 resched_curr(this_rq);
2115}
2116
2117/*
2118 * If we are not running and we are not going to reschedule soon, we should
2119 * try to push tasks away now
2120 */
2121static void task_woken_rt(struct rq *rq, struct task_struct *p)
2122{
2123 if (!task_running(rq, p) &&
2124 !test_tsk_need_resched(rq->curr) &&
2125 p->nr_cpus_allowed > 1 &&
2126 (dl_task(rq->curr) || rt_task(rq->curr)) &&
2127 (rq->curr->nr_cpus_allowed < 2 ||
2128 rq->curr->prio <= p->prio))
2129 push_rt_tasks(rq);
2130}
2131
2132/* Assumes rq->lock is held */
2133static void rq_online_rt(struct rq *rq)
2134{
2135 if (rq->rt.overloaded)
2136 rt_set_overload(rq);
2137
2138 __enable_runtime(rq);
2139
2140 cpupri_set(&rq->rd->cpupri, rq->cpu, rq->rt.highest_prio.curr);
2141}
2142
2143/* Assumes rq->lock is held */
2144static void rq_offline_rt(struct rq *rq)
2145{
2146 if (rq->rt.overloaded)
2147 rt_clear_overload(rq);
2148
2149 __disable_runtime(rq);
2150
2151 cpupri_set(&rq->rd->cpupri, rq->cpu, CPUPRI_INVALID);
2152}
2153
2154/*
2155 * When switch from the rt queue, we bring ourselves to a position
2156 * that we might want to pull RT tasks from other runqueues.
2157 */
2158static void switched_from_rt(struct rq *rq, struct task_struct *p)
2159{
2160 /*
2161 * If there are other RT tasks then we will reschedule
2162 * and the scheduling of the other RT tasks will handle
2163 * the balancing. But if we are the last RT task
2164 * we may need to handle the pulling of RT tasks
2165 * now.
2166 */
2167 if (!task_on_rq_queued(p) || rq->rt.rt_nr_running)
2168 return;
2169
2170 queue_pull_task(rq);
2171}
2172
2173void __init init_sched_rt_class(void)
2174{
2175 unsigned int i;
2176
2177 for_each_possible_cpu(i) {
2178 zalloc_cpumask_var_node(&per_cpu(local_cpu_mask, i),
2179 GFP_KERNEL, cpu_to_node(i));
2180 }
2181}
2182#endif /* CONFIG_SMP */
2183
2184/*
2185 * When switching a task to RT, we may overload the runqueue
2186 * with RT tasks. In this case we try to push them off to
2187 * other runqueues.
2188 */
2189static void switched_to_rt(struct rq *rq, struct task_struct *p)
2190{
2191 /*
2192 * If we are already running, then there's nothing
2193 * that needs to be done. But if we are not running
2194 * we may need to preempt the current running task.
2195 * If that current running task is also an RT task
2196 * then see if we can move to another run queue.
2197 */
2198 if (task_on_rq_queued(p) && rq->curr != p) {
2199#ifdef CONFIG_SMP
2200 if (p->nr_cpus_allowed > 1 && rq->rt.overloaded)
2201 queue_push_tasks(rq);
2202#else
2203 if (p->prio < rq->curr->prio)
2204 resched_curr(rq);
2205#endif /* CONFIG_SMP */
2206 }
2207}
2208
2209/*
2210 * Priority of the task has changed. This may cause
2211 * us to initiate a push or pull.
2212 */
2213static void
2214prio_changed_rt(struct rq *rq, struct task_struct *p, int oldprio)
2215{
2216 if (!task_on_rq_queued(p))
2217 return;
2218
2219 if (rq->curr == p) {
2220#ifdef CONFIG_SMP
2221 /*
2222 * If our priority decreases while running, we
2223 * may need to pull tasks to this runqueue.
2224 */
2225 if (oldprio < p->prio)
2226 queue_pull_task(rq);
2227
2228 /*
2229 * If there's a higher priority task waiting to run
2230 * then reschedule.
2231 */
2232 if (p->prio > rq->rt.highest_prio.curr)
2233 resched_curr(rq);
2234#else
2235 /* For UP simply resched on drop of prio */
2236 if (oldprio < p->prio)
2237 resched_curr(rq);
2238#endif /* CONFIG_SMP */
2239 } else {
2240 /*
2241 * This task is not running, but if it is
2242 * greater than the current running task
2243 * then reschedule.
2244 */
2245 if (p->prio < rq->curr->prio)
2246 resched_curr(rq);
2247 }
2248}
2249
2250static void watchdog(struct rq *rq, struct task_struct *p)
2251{
2252 unsigned long soft, hard;
2253
2254 /* max may change after cur was read, this will be fixed next tick */
2255 soft = task_rlimit(p, RLIMIT_RTTIME);
2256 hard = task_rlimit_max(p, RLIMIT_RTTIME);
2257
2258 if (soft != RLIM_INFINITY) {
2259 unsigned long next;
2260
2261 if (p->rt.watchdog_stamp != jiffies) {
2262 p->rt.timeout++;
2263 p->rt.watchdog_stamp = jiffies;
2264 }
2265
2266 next = DIV_ROUND_UP(min(soft, hard), USEC_PER_SEC/HZ);
2267 if (p->rt.timeout > next)
2268 p->cputime_expires.sched_exp = p->se.sum_exec_runtime;
2269 }
2270}
2271
2272static void task_tick_rt(struct rq *rq, struct task_struct *p, int queued)
2273{
2274 struct sched_rt_entity *rt_se = &p->rt;
2275
2276 update_curr_rt(rq);
2277
2278 watchdog(rq, p);
2279
2280 /*
2281 * RR tasks need a special form of timeslice management.
2282 * FIFO tasks have no timeslices.
2283 */
2284 if (p->policy != SCHED_RR)
2285 return;
2286
2287 if (--p->rt.time_slice)
2288 return;
2289
2290 p->rt.time_slice = sched_rr_timeslice;
2291
2292 /*
2293 * Requeue to the end of queue if we (and all of our ancestors) are not
2294 * the only element on the queue
2295 */
2296 for_each_sched_rt_entity(rt_se) {
2297 if (rt_se->run_list.prev != rt_se->run_list.next) {
2298 requeue_task_rt(rq, p, 0);
2299 resched_curr(rq);
2300 return;
2301 }
2302 }
2303}
2304
2305static void set_curr_task_rt(struct rq *rq)
2306{
2307 struct task_struct *p = rq->curr;
2308
2309 p->se.exec_start = rq_clock_task(rq);
2310
2311 /* The running task is never eligible for pushing */
2312 dequeue_pushable_task(rq, p);
2313}
2314
2315static unsigned int get_rr_interval_rt(struct rq *rq, struct task_struct *task)
2316{
2317 /*
2318 * Time slice is 0 for SCHED_FIFO tasks
2319 */
2320 if (task->policy == SCHED_RR)
2321 return sched_rr_timeslice;
2322 else
2323 return 0;
2324}
2325
2326const struct sched_class rt_sched_class = {
2327 .next = &fair_sched_class,
2328 .enqueue_task = enqueue_task_rt,
2329 .dequeue_task = dequeue_task_rt,
2330 .yield_task = yield_task_rt,
2331
2332 .check_preempt_curr = check_preempt_curr_rt,
2333
2334 .pick_next_task = pick_next_task_rt,
2335 .put_prev_task = put_prev_task_rt,
2336
2337#ifdef CONFIG_SMP
2338 .select_task_rq = select_task_rq_rt,
2339
2340 .set_cpus_allowed = set_cpus_allowed_common,
2341 .rq_online = rq_online_rt,
2342 .rq_offline = rq_offline_rt,
2343 .task_woken = task_woken_rt,
2344 .switched_from = switched_from_rt,
2345#endif
2346
2347 .set_curr_task = set_curr_task_rt,
2348 .task_tick = task_tick_rt,
2349
2350 .get_rr_interval = get_rr_interval_rt,
2351
2352 .prio_changed = prio_changed_rt,
2353 .switched_to = switched_to_rt,
2354
2355 .update_curr = update_curr_rt,
2356};
2357
2358#ifdef CONFIG_SCHED_DEBUG
2359extern void print_rt_rq(struct seq_file *m, int cpu, struct rt_rq *rt_rq);
2360
2361void print_rt_stats(struct seq_file *m, int cpu)
2362{
2363 rt_rq_iter_t iter;
2364 struct rt_rq *rt_rq;
2365
2366 rcu_read_lock();
2367 for_each_rt_rq(rt_rq, iter, cpu_rq(cpu))
2368 print_rt_rq(m, cpu, rt_rq);
2369 rcu_read_unlock();
2370}
2371#endif /* CONFIG_SCHED_DEBUG */