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 
7 int sched_rr_timeslice = RR_TIMESLICE;
8 /* More than 4 hours if BW_SHIFT equals 20. */
9 static const u64 max_rt_runtime = MAX_BW;
10 
11 static int do_sched_rt_period_timer(struct rt_bandwidth *rt_b, int overrun);
12 
13 struct rt_bandwidth def_rt_bandwidth;
14 
15 /*
16  * period over which we measure -rt task CPU usage in us.
17  * default: 1s
18  */
19 unsigned 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  */
25 int sysctl_sched_rt_runtime = 950000;
26 
27 #ifdef CONFIG_SYSCTL
28 static int sysctl_sched_rr_timeslice = (MSEC_PER_SEC / HZ) * RR_TIMESLICE;
29 static int sched_rt_handler(struct ctl_table *table, int write, void *buffer,
30 		size_t *lenp, loff_t *ppos);
31 static int sched_rr_handler(struct ctl_table *table, int write, void *buffer,
32 		size_t *lenp, loff_t *ppos);
33 static 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 
sched_rt_sysctl_init(void)58 static int __init sched_rt_sysctl_init(void)
59 {
60 	register_sysctl_init("kernel", sched_rt_sysctls);
61 	return 0;
62 }
63 late_initcall(sched_rt_sysctl_init);
64 #endif
65 
sched_rt_period_timer(struct hrtimer * timer)66 static 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 
init_rt_bandwidth(struct rt_bandwidth * rt_b,u64 period,u64 runtime)90 void 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 
do_start_rt_bandwidth(struct rt_bandwidth * rt_b)102 static 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 
start_rt_bandwidth(struct rt_bandwidth * rt_b)122 static 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 
init_rt_rq(struct rt_rq * rt_rq)130 void 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
destroy_rt_bandwidth(struct rt_bandwidth * rt_b)160 static 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 
rt_task_of(struct sched_rt_entity * rt_se)167 static 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 
rq_of_rt_rq(struct rt_rq * rt_rq)175 static inline struct rq *rq_of_rt_rq(struct rt_rq *rt_rq)
176 {
177 	return rt_rq->rq;
178 }
179 
rt_rq_of_se(struct sched_rt_entity * rt_se)180 static inline struct rt_rq *rt_rq_of_se(struct sched_rt_entity *rt_se)
181 {
182 	return rt_se->rt_rq;
183 }
184 
rq_of_rt_se(struct sched_rt_entity * rt_se)185 static 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 
unregister_rt_sched_group(struct task_group * tg)192 void unregister_rt_sched_group(struct task_group *tg)
193 {
194 	if (tg->rt_se)
195 		destroy_rt_bandwidth(&tg->rt_bandwidth);
196 
197 }
198 
free_rt_sched_group(struct task_group * tg)199 void 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 
init_tg_rt_entry(struct task_group * tg,struct rt_rq * rt_rq,struct sched_rt_entity * rt_se,int cpu,struct sched_rt_entity * parent)214 void 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 
alloc_rt_sched_group(struct task_group * tg,struct task_group * parent)241 int 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 
275 err_free_rq:
276 	kfree(rt_rq);
277 err:
278 	return 0;
279 }
280 
281 #else /* CONFIG_RT_GROUP_SCHED */
282 
283 #define rt_entity_is_task(rt_se) (1)
284 
rt_task_of(struct sched_rt_entity * rt_se)285 static 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 
rq_of_rt_rq(struct rt_rq * rt_rq)290 static inline struct rq *rq_of_rt_rq(struct rt_rq *rt_rq)
291 {
292 	return container_of(rt_rq, struct rq, rt);
293 }
294 
rq_of_rt_se(struct sched_rt_entity * rt_se)295 static 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 
rt_rq_of_se(struct sched_rt_entity * rt_se)302 static 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 
unregister_rt_sched_group(struct task_group * tg)309 void unregister_rt_sched_group(struct task_group *tg) { }
310 
free_rt_sched_group(struct task_group * tg)311 void free_rt_sched_group(struct task_group *tg) { }
312 
alloc_rt_sched_group(struct task_group * tg,struct task_group * parent)313 int 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 
need_pull_rt_task(struct rq * rq,struct task_struct * prev)321 static 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 
rt_overloaded(struct rq * rq)327 static inline int rt_overloaded(struct rq *rq)
328 {
329 	return atomic_read(&rq->rd->rto_count);
330 }
331 
rt_set_overload(struct rq * rq)332 static 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 
rt_clear_overload(struct rq * rq)351 static 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 
update_rt_migration(struct rt_rq * rt_rq)361 static 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 
inc_rt_migration(struct sched_rt_entity * rt_se,struct rt_rq * rt_rq)374 static 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 
dec_rt_migration(struct sched_rt_entity * rt_se,struct rt_rq * rt_rq)391 static 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 
has_pushable_tasks(struct rq * rq)408 static inline int has_pushable_tasks(struct rq *rq)
409 {
410 	return !plist_head_empty(&rq->rt.pushable_tasks);
411 }
412 
413 static DEFINE_PER_CPU(struct balance_callback, rt_push_head);
414 static DEFINE_PER_CPU(struct balance_callback, rt_pull_head);
415 
416 static void push_rt_tasks(struct rq *);
417 static void pull_rt_task(struct rq *);
418 
rt_queue_push_tasks(struct rq * rq)419 static 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 
rt_queue_pull_task(struct rq * rq)427 static 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 
enqueue_pushable_task(struct rq * rq,struct task_struct * p)432 static 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 
dequeue_pushable_task(struct rq * rq,struct task_struct * p)443 static 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 
enqueue_pushable_task(struct rq * rq,struct task_struct * p)459 static inline void enqueue_pushable_task(struct rq *rq, struct task_struct *p)
460 {
461 }
462 
dequeue_pushable_task(struct rq * rq,struct task_struct * p)463 static inline void dequeue_pushable_task(struct rq *rq, struct task_struct *p)
464 {
465 }
466 
467 static inline
inc_rt_migration(struct sched_rt_entity * rt_se,struct rt_rq * rt_rq)468 void inc_rt_migration(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
469 {
470 }
471 
472 static inline
dec_rt_migration(struct sched_rt_entity * rt_se,struct rt_rq * rt_rq)473 void dec_rt_migration(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
474 {
475 }
476 
rt_queue_push_tasks(struct rq * rq)477 static inline void rt_queue_push_tasks(struct rq *rq)
478 {
479 }
480 #endif /* CONFIG_SMP */
481 
482 static void enqueue_top_rt_rq(struct rt_rq *rt_rq);
483 static void dequeue_top_rt_rq(struct rt_rq *rt_rq, unsigned int count);
484 
on_rt_rq(struct sched_rt_entity * rt_se)485 static 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  */
rt_task_fits_capacity(struct task_struct * p,int cpu)505 static 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
rt_task_fits_capacity(struct task_struct * p,int cpu)523 static 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 
sched_rt_runtime(struct rt_rq * rt_rq)531 static 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 
sched_rt_period(struct rt_rq * rt_rq)539 static 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 
544 typedef struct task_group *rt_rq_iter_t;
545 
next_task_group(struct task_group * tg)546 static 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 
group_rt_rq(struct sched_rt_entity * rt_se)567 static inline struct rt_rq *group_rt_rq(struct sched_rt_entity *rt_se)
568 {
569 	return rt_se->my_q;
570 }
571 
572 static void enqueue_rt_entity(struct sched_rt_entity *rt_se, unsigned int flags);
573 static void dequeue_rt_entity(struct sched_rt_entity *rt_se, unsigned int flags);
574 
sched_rt_rq_enqueue(struct rt_rq * rt_rq)575 static 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 
sched_rt_rq_dequeue(struct rt_rq * rt_rq)596 static 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 
rt_rq_throttled(struct rt_rq * rt_rq)612 static inline int rt_rq_throttled(struct rt_rq *rt_rq)
613 {
614 	return rt_rq->rt_throttled && !rt_rq->rt_nr_boosted;
615 }
616 
rt_se_boosted(struct sched_rt_entity * rt_se)617 static 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
sched_rt_period_mask(void)630 static inline const struct cpumask *sched_rt_period_mask(void)
631 {
632 	return this_rq()->rd->span;
633 }
634 #else
sched_rt_period_mask(void)635 static inline const struct cpumask *sched_rt_period_mask(void)
636 {
637 	return cpu_online_mask;
638 }
639 #endif
640 
641 static inline
sched_rt_period_rt_rq(struct rt_bandwidth * rt_b,int cpu)642 struct 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 
sched_rt_bandwidth(struct rt_rq * rt_rq)647 static 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 
sched_rt_runtime(struct rt_rq * rt_rq)654 static inline u64 sched_rt_runtime(struct rt_rq *rt_rq)
655 {
656 	return rt_rq->rt_runtime;
657 }
658 
sched_rt_period(struct rt_rq * rt_rq)659 static inline u64 sched_rt_period(struct rt_rq *rt_rq)
660 {
661 	return ktime_to_ns(def_rt_bandwidth.rt_period);
662 }
663 
664 typedef 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 
group_rt_rq(struct sched_rt_entity * rt_se)672 static inline struct rt_rq *group_rt_rq(struct sched_rt_entity *rt_se)
673 {
674 	return NULL;
675 }
676 
sched_rt_rq_enqueue(struct rt_rq * rt_rq)677 static 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 
sched_rt_rq_dequeue(struct rt_rq * rt_rq)688 static 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 
rt_rq_throttled(struct rt_rq * rt_rq)693 static inline int rt_rq_throttled(struct rt_rq *rt_rq)
694 {
695 	return rt_rq->rt_throttled;
696 }
697 
sched_rt_period_mask(void)698 static inline const struct cpumask *sched_rt_period_mask(void)
699 {
700 	return cpu_online_mask;
701 }
702 
703 static inline
sched_rt_period_rt_rq(struct rt_bandwidth * rt_b,int cpu)704 struct rt_rq *sched_rt_period_rt_rq(struct rt_bandwidth *rt_b, int cpu)
705 {
706 	return &cpu_rq(cpu)->rt;
707 }
708 
sched_rt_bandwidth(struct rt_rq * rt_rq)709 static 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 
sched_rt_bandwidth_account(struct rt_rq * rt_rq)716 bool 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  */
do_balance_runtime(struct rt_rq * rt_rq)728 static 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 		}
771 next:
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  */
__disable_runtime(struct rq * rq)780 static 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);
847 balanced:
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 
__enable_runtime(struct rq * rq)862 static 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 
balance_runtime(struct rt_rq * rt_rq)886 static 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 */
balance_runtime(struct rt_rq * rt_rq)898 static inline void balance_runtime(struct rt_rq *rt_rq) {}
899 #endif /* CONFIG_SMP */
900 
do_sched_rt_period_timer(struct rt_bandwidth * rt_b,int overrun)901 static 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 
rt_se_prio(struct sched_rt_entity * rt_se)986 static 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 
sched_rt_runtime_exceeded(struct rt_rq * rt_rq)998 static 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  */
update_curr_rt(struct rq * rq)1045 static 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 
1087 static void
dequeue_top_rt_rq(struct rt_rq * rt_rq,unsigned int count)1088 dequeue_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 
1104 static void
enqueue_top_rt_rq(struct rt_rq * rt_rq)1105 enqueue_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 
1128 static void
inc_rt_prio_smp(struct rt_rq * rt_rq,int prio,int prev_prio)1129 inc_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 
1144 static void
dec_rt_prio_smp(struct rt_rq * rt_rq,int prio,int prev_prio)1145 dec_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 
1162 static inline
inc_rt_prio_smp(struct rt_rq * rt_rq,int prio,int prev_prio)1163 void inc_rt_prio_smp(struct rt_rq *rt_rq, int prio, int prev_prio) {}
1164 static inline
dec_rt_prio_smp(struct rt_rq * rt_rq,int prio,int prev_prio)1165 void 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
1170 static void
inc_rt_prio(struct rt_rq * rt_rq,int prio)1171 inc_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 
1181 static void
dec_rt_prio(struct rt_rq * rt_rq,int prio)1182 dec_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 
inc_rt_prio(struct rt_rq * rt_rq,int prio)1210 static inline void inc_rt_prio(struct rt_rq *rt_rq, int prio) {}
dec_rt_prio(struct rt_rq * rt_rq,int prio)1211 static 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 
1217 static void
inc_rt_group(struct sched_rt_entity * rt_se,struct rt_rq * rt_rq)1218 inc_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 
1227 static void
dec_rt_group(struct sched_rt_entity * rt_se,struct rt_rq * rt_rq)1228 dec_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 
1238 static void
inc_rt_group(struct sched_rt_entity * rt_se,struct rt_rq * rt_rq)1239 inc_rt_group(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
1240 {
1241 	start_rt_bandwidth(&def_rt_bandwidth);
1242 }
1243 
1244 static inline
dec_rt_group(struct sched_rt_entity * rt_se,struct rt_rq * rt_rq)1245 void dec_rt_group(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq) {}
1246 
1247 #endif /* CONFIG_RT_GROUP_SCHED */
1248 
1249 static inline
rt_se_nr_running(struct sched_rt_entity * rt_se)1250 unsigned 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 
1260 static inline
rt_se_rr_nr_running(struct sched_rt_entity * rt_se)1261 unsigned 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 
1274 static inline
inc_rt_tasks(struct sched_rt_entity * rt_se,struct rt_rq * rt_rq)1275 void 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 
1288 static inline
dec_rt_tasks(struct sched_rt_entity * rt_se,struct rt_rq * rt_rq)1289 void 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  */
move_entity(unsigned int flags)1306 static 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 
__delist_rt_entity(struct sched_rt_entity * rt_se,struct rt_prio_array * array)1314 static 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 
1324 static inline struct sched_statistics *
__schedstats_from_rt_se(struct sched_rt_entity * rt_se)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 
1336 static inline void
update_stats_wait_start_rt(struct rt_rq * rt_rq,struct sched_rt_entity * rt_se)1337 update_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 
1355 static inline void
update_stats_enqueue_sleeper_rt(struct rt_rq * rt_rq,struct sched_rt_entity * rt_se)1356 update_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 
1374 static inline void
update_stats_enqueue_rt(struct rt_rq * rt_rq,struct sched_rt_entity * rt_se,int flags)1375 update_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 
1385 static inline void
update_stats_wait_end_rt(struct rt_rq * rt_rq,struct sched_rt_entity * rt_se)1386 update_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 
1404 static inline void
update_stats_dequeue_rt(struct rt_rq * rt_rq,struct sched_rt_entity * rt_se,int flags)1405 update_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 
__enqueue_rt_entity(struct sched_rt_entity * rt_se,unsigned int flags)1430 static 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 
__dequeue_rt_entity(struct sched_rt_entity * rt_se,unsigned int flags)1464 static 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  */
dequeue_rt_stack(struct sched_rt_entity * rt_se,unsigned int flags)1482 static 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 
enqueue_rt_entity(struct sched_rt_entity * rt_se,unsigned int flags)1502 static 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 
dequeue_rt_entity(struct sched_rt_entity * rt_se,unsigned int flags)1514 static 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  */
1534 static void
enqueue_task_rt(struct rq * rq,struct task_struct * p,int flags)1535 enqueue_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 
dequeue_task_rt(struct rq * rq,struct task_struct * p,int flags)1551 static 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  */
1565 static void
requeue_rt_entity(struct rt_rq * rt_rq,struct sched_rt_entity * rt_se,int head)1566 requeue_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 
requeue_task_rt(struct rq * rq,struct task_struct * p,int head)1579 static 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 
yield_task_rt(struct rq * rq)1590 static void yield_task_rt(struct rq *rq)
1591 {
1592 	requeue_task_rt(rq, rq->curr, 0);
1593 }
1594 
1595 #ifdef CONFIG_SMP
1596 static int find_lowest_rq(struct task_struct *task);
1597 
1598 static int
select_task_rq_rt(struct task_struct * p,int cpu,int flags)1599 select_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 
1663 out_unlock:
1664 	rcu_read_unlock();
1665 
1666 out:
1667 	return cpu;
1668 }
1669 
check_preempt_equal_prio(struct rq * rq,struct task_struct * p)1670 static 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 
balance_rt(struct rq * rq,struct task_struct * p,struct rq_flags * rf)1697 static 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  */
check_preempt_curr_rt(struct rq * rq,struct task_struct * p,int flags)1718 static 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 
set_next_task_rt(struct rq * rq,struct task_struct * p,bool first)1743 static 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 
pick_next_rt_entity(struct rt_rq * rt_rq)1769 static 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 
_pick_next_task_rt(struct rq * rq)1785 static 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 
pick_task_rt(struct rq * rq)1799 static 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 
pick_next_task_rt(struct rq * rq)1811 static 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 
put_prev_task_rt(struct rq * rq,struct task_struct * p)1821 static 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 
pick_rt_task(struct rq * rq,struct task_struct * p,int cpu)1846 static 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  */
pick_highest_pushable_task(struct rq * rq,int cpu)1859 static 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 
1875 static DEFINE_PER_CPU(cpumask_var_t, local_cpu_mask);
1876 
find_lowest_rq(struct task_struct * task)1877 static 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 */
find_lock_lowest_rq(struct task_struct * task,struct rq * rq)1969 static 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 
pick_next_pushable_task(struct rq * rq)2025 static 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  */
push_rt_task(struct rq * rq,bool pull)2050 static 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 
2063 retry:
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);
2162 out:
2163 	put_task_struct(next_task);
2164 
2165 	return ret;
2166 }
2167 
push_rt_tasks(struct rq * rq)2168 static 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  */
rto_next_cpu(struct root_domain * rd)2218 static 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 
rto_start_trylock(atomic_t * v)2265 static inline bool rto_start_trylock(atomic_t *v)
2266 {
2267 	return !atomic_cmpxchg_acquire(v, 0, 1);
2268 }
2269 
rto_start_unlock(atomic_t * v)2270 static inline void rto_start_unlock(atomic_t *v)
2271 {
2272 	atomic_set_release(v, 0);
2273 }
2274 
tell_cpu_to_push(struct rq * rq)2275 static 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 */
rto_push_irq_work_func(struct irq_work * work)2309 void 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 
pull_rt_task(struct rq * this_rq)2346 static 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 		}
2440 skip:
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  */
task_woken_rt(struct rq * rq,struct task_struct * p)2459 static 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 */
rq_online_rt(struct rq * rq)2473 static 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 */
rq_offline_rt(struct rq * rq)2484 static 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  */
switched_from_rt(struct rq * rq,struct task_struct * p)2498 static 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 
init_sched_rt_class(void)2513 void __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  */
switched_to_rt(struct rq * rq,struct task_struct * p)2529 static 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  */
2559 static void
prio_changed_rt(struct rq * rq,struct task_struct * p,int oldprio)2560 prio_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
watchdog(struct rq * rq,struct task_struct * p)2597 static 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
watchdog(struct rq * rq,struct task_struct * p)2621 static 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  */
task_tick_rt(struct rq * rq,struct task_struct * p,int queued)2632 static 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 
get_rr_interval_rt(struct rq * rq,struct task_struct * task)2666 static 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 
2677 DEFINE_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  */
2719 static DEFINE_MUTEX(rt_constraints_mutex);
2720 
tg_has_rt_tasks(struct task_group * tg)2721 static 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 
2741 struct rt_schedulable_data {
2742 	struct task_group *tg;
2743 	u64 rt_period;
2744 	u64 rt_runtime;
2745 };
2746 
tg_rt_schedulable(struct task_group * tg,void * data)2747 static 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 
__rt_schedulable(struct task_group * tg,u64 period,u64 runtime)2804 static 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 
tg_set_rt_bandwidth(struct task_group * tg,u64 rt_period,u64 rt_runtime)2821 static 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);
2860 unlock:
2861 	mutex_unlock(&rt_constraints_mutex);
2862 
2863 	return err;
2864 }
2865 
sched_group_set_rt_runtime(struct task_group * tg,long rt_runtime_us)2866 int 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 
sched_group_rt_runtime(struct task_group * tg)2880 long 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 
sched_group_set_rt_period(struct task_group * tg,u64 rt_period_us)2892 int 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 
sched_group_rt_period(struct task_group * tg)2905 long 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
sched_rt_global_constraints(void)2915 static 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 
sched_rt_can_attach(struct task_group * tg,struct task_struct * tsk)2927 int 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
sched_rt_global_constraints(void)2939 static 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
sched_rt_global_validate(void)2960 static 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 
sched_rt_do_global(void)2974 static 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 
sched_rt_handler(struct ctl_table * table,int write,void * buffer,size_t * lenp,loff_t * ppos)2984 static 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) {
3014 undo:
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 
sched_rr_handler(struct ctl_table * table,int write,void * buffer,size_t * lenp,loff_t * ppos)3023 static 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
print_rt_stats(struct seq_file * m,int cpu)3047 void 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 */
3058