Line data Source code
1 : // SPDX-License-Identifier: GPL-2.0
2 : /*
3 : * Deadline Scheduling Class (SCHED_DEADLINE)
4 : *
5 : * Earliest Deadline First (EDF) + Constant Bandwidth Server (CBS).
6 : *
7 : * Tasks that periodically executes their instances for less than their
8 : * runtime won't miss any of their deadlines.
9 : * Tasks that are not periodic or sporadic or that tries to execute more
10 : * than their reserved bandwidth will be slowed down (and may potentially
11 : * miss some of their deadlines), and won't affect any other task.
12 : *
13 : * Copyright (C) 2012 Dario Faggioli <raistlin@linux.it>,
14 : * Juri Lelli <juri.lelli@gmail.com>,
15 : * Michael Trimarchi <michael@amarulasolutions.com>,
16 : * Fabio Checconi <fchecconi@gmail.com>
17 : */
18 :
19 : /*
20 : * Default limits for DL period; on the top end we guard against small util
21 : * tasks still getting ridiculously long effective runtimes, on the bottom end we
22 : * guard against timer DoS.
23 : */
24 : static unsigned int sysctl_sched_dl_period_max = 1 << 22; /* ~4 seconds */
25 : static unsigned int sysctl_sched_dl_period_min = 100; /* 100 us */
26 : #ifdef CONFIG_SYSCTL
27 : static struct ctl_table sched_dl_sysctls[] = {
28 : {
29 : .procname = "sched_deadline_period_max_us",
30 : .data = &sysctl_sched_dl_period_max,
31 : .maxlen = sizeof(unsigned int),
32 : .mode = 0644,
33 : .proc_handler = proc_douintvec_minmax,
34 : .extra1 = (void *)&sysctl_sched_dl_period_min,
35 : },
36 : {
37 : .procname = "sched_deadline_period_min_us",
38 : .data = &sysctl_sched_dl_period_min,
39 : .maxlen = sizeof(unsigned int),
40 : .mode = 0644,
41 : .proc_handler = proc_douintvec_minmax,
42 : .extra2 = (void *)&sysctl_sched_dl_period_max,
43 : },
44 : {}
45 : };
46 :
47 1 : static int __init sched_dl_sysctl_init(void)
48 : {
49 1 : register_sysctl_init("kernel", sched_dl_sysctls);
50 1 : return 0;
51 : }
52 : late_initcall(sched_dl_sysctl_init);
53 : #endif
54 :
55 : static inline struct task_struct *dl_task_of(struct sched_dl_entity *dl_se)
56 : {
57 0 : return container_of(dl_se, struct task_struct, dl);
58 : }
59 :
60 : static inline struct rq *rq_of_dl_rq(struct dl_rq *dl_rq)
61 : {
62 0 : return container_of(dl_rq, struct rq, dl);
63 : }
64 :
65 : static inline struct dl_rq *dl_rq_of_se(struct sched_dl_entity *dl_se)
66 : {
67 0 : struct task_struct *p = dl_task_of(dl_se);
68 0 : struct rq *rq = task_rq(p);
69 :
70 : return &rq->dl;
71 : }
72 :
73 : static inline int on_dl_rq(struct sched_dl_entity *dl_se)
74 : {
75 0 : return !RB_EMPTY_NODE(&dl_se->rb_node);
76 : }
77 :
78 : #ifdef CONFIG_RT_MUTEXES
79 : static inline struct sched_dl_entity *pi_of(struct sched_dl_entity *dl_se)
80 : {
81 : return dl_se->pi_se;
82 : }
83 :
84 : static inline bool is_dl_boosted(struct sched_dl_entity *dl_se)
85 : {
86 0 : return pi_of(dl_se) != dl_se;
87 : }
88 : #else
89 : static inline struct sched_dl_entity *pi_of(struct sched_dl_entity *dl_se)
90 : {
91 : return dl_se;
92 : }
93 :
94 : static inline bool is_dl_boosted(struct sched_dl_entity *dl_se)
95 : {
96 : return false;
97 : }
98 : #endif
99 :
100 : #ifdef CONFIG_SMP
101 : static inline struct dl_bw *dl_bw_of(int i)
102 : {
103 : RCU_LOCKDEP_WARN(!rcu_read_lock_sched_held(),
104 : "sched RCU must be held");
105 : return &cpu_rq(i)->rd->dl_bw;
106 : }
107 :
108 : static inline int dl_bw_cpus(int i)
109 : {
110 : struct root_domain *rd = cpu_rq(i)->rd;
111 : int cpus;
112 :
113 : RCU_LOCKDEP_WARN(!rcu_read_lock_sched_held(),
114 : "sched RCU must be held");
115 :
116 : if (cpumask_subset(rd->span, cpu_active_mask))
117 : return cpumask_weight(rd->span);
118 :
119 : cpus = 0;
120 :
121 : for_each_cpu_and(i, rd->span, cpu_active_mask)
122 : cpus++;
123 :
124 : return cpus;
125 : }
126 :
127 : static inline unsigned long __dl_bw_capacity(const struct cpumask *mask)
128 : {
129 : unsigned long cap = 0;
130 : int i;
131 :
132 : for_each_cpu_and(i, mask, cpu_active_mask)
133 : cap += capacity_orig_of(i);
134 :
135 : return cap;
136 : }
137 :
138 : /*
139 : * XXX Fix: If 'rq->rd == def_root_domain' perform AC against capacity
140 : * of the CPU the task is running on rather rd's \Sum CPU capacity.
141 : */
142 : static inline unsigned long dl_bw_capacity(int i)
143 : {
144 : if (!sched_asym_cpucap_active() &&
145 : capacity_orig_of(i) == SCHED_CAPACITY_SCALE) {
146 : return dl_bw_cpus(i) << SCHED_CAPACITY_SHIFT;
147 : } else {
148 : RCU_LOCKDEP_WARN(!rcu_read_lock_sched_held(),
149 : "sched RCU must be held");
150 :
151 : return __dl_bw_capacity(cpu_rq(i)->rd->span);
152 : }
153 : }
154 :
155 : static inline bool dl_bw_visited(int cpu, u64 gen)
156 : {
157 : struct root_domain *rd = cpu_rq(cpu)->rd;
158 :
159 : if (rd->visit_gen == gen)
160 : return true;
161 :
162 : rd->visit_gen = gen;
163 : return false;
164 : }
165 :
166 : static inline
167 : void __dl_update(struct dl_bw *dl_b, s64 bw)
168 : {
169 : struct root_domain *rd = container_of(dl_b, struct root_domain, dl_bw);
170 : int i;
171 :
172 : RCU_LOCKDEP_WARN(!rcu_read_lock_sched_held(),
173 : "sched RCU must be held");
174 : for_each_cpu_and(i, rd->span, cpu_active_mask) {
175 : struct rq *rq = cpu_rq(i);
176 :
177 : rq->dl.extra_bw += bw;
178 : }
179 : }
180 : #else
181 : static inline struct dl_bw *dl_bw_of(int i)
182 : {
183 0 : return &cpu_rq(i)->dl.dl_bw;
184 : }
185 :
186 : static inline int dl_bw_cpus(int i)
187 : {
188 : return 1;
189 : }
190 :
191 : static inline unsigned long dl_bw_capacity(int i)
192 : {
193 : return SCHED_CAPACITY_SCALE;
194 : }
195 :
196 : static inline bool dl_bw_visited(int cpu, u64 gen)
197 : {
198 : return false;
199 : }
200 :
201 : static inline
202 : void __dl_update(struct dl_bw *dl_b, s64 bw)
203 : {
204 0 : struct dl_rq *dl = container_of(dl_b, struct dl_rq, dl_bw);
205 :
206 0 : dl->extra_bw += bw;
207 : }
208 : #endif
209 :
210 : static inline
211 : void __dl_sub(struct dl_bw *dl_b, u64 tsk_bw, int cpus)
212 : {
213 0 : dl_b->total_bw -= tsk_bw;
214 0 : __dl_update(dl_b, (s32)tsk_bw / cpus);
215 : }
216 :
217 : static inline
218 : void __dl_add(struct dl_bw *dl_b, u64 tsk_bw, int cpus)
219 : {
220 0 : dl_b->total_bw += tsk_bw;
221 0 : __dl_update(dl_b, -((s32)tsk_bw / cpus));
222 : }
223 :
224 : static inline bool
225 : __dl_overflow(struct dl_bw *dl_b, unsigned long cap, u64 old_bw, u64 new_bw)
226 : {
227 0 : return dl_b->bw != -1 &&
228 0 : cap_scale(dl_b->bw, cap) < dl_b->total_bw - old_bw + new_bw;
229 : }
230 :
231 : static inline
232 0 : void __add_running_bw(u64 dl_bw, struct dl_rq *dl_rq)
233 : {
234 0 : u64 old = dl_rq->running_bw;
235 :
236 0 : lockdep_assert_rq_held(rq_of_dl_rq(dl_rq));
237 0 : dl_rq->running_bw += dl_bw;
238 0 : SCHED_WARN_ON(dl_rq->running_bw < old); /* overflow */
239 0 : SCHED_WARN_ON(dl_rq->running_bw > dl_rq->this_bw);
240 : /* kick cpufreq (see the comment in kernel/sched/sched.h). */
241 0 : cpufreq_update_util(rq_of_dl_rq(dl_rq), 0);
242 0 : }
243 :
244 : static inline
245 0 : void __sub_running_bw(u64 dl_bw, struct dl_rq *dl_rq)
246 : {
247 0 : u64 old = dl_rq->running_bw;
248 :
249 0 : lockdep_assert_rq_held(rq_of_dl_rq(dl_rq));
250 0 : dl_rq->running_bw -= dl_bw;
251 0 : SCHED_WARN_ON(dl_rq->running_bw > old); /* underflow */
252 0 : if (dl_rq->running_bw > old)
253 0 : dl_rq->running_bw = 0;
254 : /* kick cpufreq (see the comment in kernel/sched/sched.h). */
255 0 : cpufreq_update_util(rq_of_dl_rq(dl_rq), 0);
256 0 : }
257 :
258 : static inline
259 0 : void __add_rq_bw(u64 dl_bw, struct dl_rq *dl_rq)
260 : {
261 0 : u64 old = dl_rq->this_bw;
262 :
263 0 : lockdep_assert_rq_held(rq_of_dl_rq(dl_rq));
264 0 : dl_rq->this_bw += dl_bw;
265 0 : SCHED_WARN_ON(dl_rq->this_bw < old); /* overflow */
266 0 : }
267 :
268 : static inline
269 0 : void __sub_rq_bw(u64 dl_bw, struct dl_rq *dl_rq)
270 : {
271 0 : u64 old = dl_rq->this_bw;
272 :
273 0 : lockdep_assert_rq_held(rq_of_dl_rq(dl_rq));
274 0 : dl_rq->this_bw -= dl_bw;
275 0 : SCHED_WARN_ON(dl_rq->this_bw > old); /* underflow */
276 0 : if (dl_rq->this_bw > old)
277 0 : dl_rq->this_bw = 0;
278 0 : SCHED_WARN_ON(dl_rq->running_bw > dl_rq->this_bw);
279 0 : }
280 :
281 : static inline
282 : void add_rq_bw(struct sched_dl_entity *dl_se, struct dl_rq *dl_rq)
283 : {
284 0 : if (!dl_entity_is_special(dl_se))
285 0 : __add_rq_bw(dl_se->dl_bw, dl_rq);
286 : }
287 :
288 : static inline
289 : void sub_rq_bw(struct sched_dl_entity *dl_se, struct dl_rq *dl_rq)
290 : {
291 0 : if (!dl_entity_is_special(dl_se))
292 0 : __sub_rq_bw(dl_se->dl_bw, dl_rq);
293 : }
294 :
295 : static inline
296 : void add_running_bw(struct sched_dl_entity *dl_se, struct dl_rq *dl_rq)
297 : {
298 0 : if (!dl_entity_is_special(dl_se))
299 0 : __add_running_bw(dl_se->dl_bw, dl_rq);
300 : }
301 :
302 : static inline
303 : void sub_running_bw(struct sched_dl_entity *dl_se, struct dl_rq *dl_rq)
304 : {
305 0 : if (!dl_entity_is_special(dl_se))
306 0 : __sub_running_bw(dl_se->dl_bw, dl_rq);
307 : }
308 :
309 0 : static void dl_change_utilization(struct task_struct *p, u64 new_bw)
310 : {
311 : struct rq *rq;
312 :
313 0 : WARN_ON_ONCE(p->dl.flags & SCHED_FLAG_SUGOV);
314 :
315 0 : if (task_on_rq_queued(p))
316 : return;
317 :
318 0 : rq = task_rq(p);
319 0 : if (p->dl.dl_non_contending) {
320 0 : sub_running_bw(&p->dl, &rq->dl);
321 0 : p->dl.dl_non_contending = 0;
322 : /*
323 : * If the timer handler is currently running and the
324 : * timer cannot be canceled, inactive_task_timer()
325 : * will see that dl_not_contending is not set, and
326 : * will not touch the rq's active utilization,
327 : * so we are still safe.
328 : */
329 0 : if (hrtimer_try_to_cancel(&p->dl.inactive_timer) == 1)
330 0 : put_task_struct(p);
331 : }
332 0 : __sub_rq_bw(p->dl.dl_bw, &rq->dl);
333 0 : __add_rq_bw(new_bw, &rq->dl);
334 : }
335 :
336 : /*
337 : * The utilization of a task cannot be immediately removed from
338 : * the rq active utilization (running_bw) when the task blocks.
339 : * Instead, we have to wait for the so called "0-lag time".
340 : *
341 : * If a task blocks before the "0-lag time", a timer (the inactive
342 : * timer) is armed, and running_bw is decreased when the timer
343 : * fires.
344 : *
345 : * If the task wakes up again before the inactive timer fires,
346 : * the timer is canceled, whereas if the task wakes up after the
347 : * inactive timer fired (and running_bw has been decreased) the
348 : * task's utilization has to be added to running_bw again.
349 : * A flag in the deadline scheduling entity (dl_non_contending)
350 : * is used to avoid race conditions between the inactive timer handler
351 : * and task wakeups.
352 : *
353 : * The following diagram shows how running_bw is updated. A task is
354 : * "ACTIVE" when its utilization contributes to running_bw; an
355 : * "ACTIVE contending" task is in the TASK_RUNNING state, while an
356 : * "ACTIVE non contending" task is a blocked task for which the "0-lag time"
357 : * has not passed yet. An "INACTIVE" task is a task for which the "0-lag"
358 : * time already passed, which does not contribute to running_bw anymore.
359 : * +------------------+
360 : * wakeup | ACTIVE |
361 : * +------------------>+ contending |
362 : * | add_running_bw | |
363 : * | +----+------+------+
364 : * | | ^
365 : * | dequeue | |
366 : * +--------+-------+ | |
367 : * | | t >= 0-lag | | wakeup
368 : * | INACTIVE |<---------------+ |
369 : * | | sub_running_bw | |
370 : * +--------+-------+ | |
371 : * ^ | |
372 : * | t < 0-lag | |
373 : * | | |
374 : * | V |
375 : * | +----+------+------+
376 : * | sub_running_bw | ACTIVE |
377 : * +-------------------+ |
378 : * inactive timer | non contending |
379 : * fired +------------------+
380 : *
381 : * The task_non_contending() function is invoked when a task
382 : * blocks, and checks if the 0-lag time already passed or
383 : * not (in the first case, it directly updates running_bw;
384 : * in the second case, it arms the inactive timer).
385 : *
386 : * The task_contending() function is invoked when a task wakes
387 : * up, and checks if the task is still in the "ACTIVE non contending"
388 : * state or not (in the second case, it updates running_bw).
389 : */
390 0 : static void task_non_contending(struct task_struct *p)
391 : {
392 0 : struct sched_dl_entity *dl_se = &p->dl;
393 0 : struct hrtimer *timer = &dl_se->inactive_timer;
394 0 : struct dl_rq *dl_rq = dl_rq_of_se(dl_se);
395 0 : struct rq *rq = rq_of_dl_rq(dl_rq);
396 : s64 zerolag_time;
397 :
398 : /*
399 : * If this is a non-deadline task that has been boosted,
400 : * do nothing
401 : */
402 0 : if (dl_se->dl_runtime == 0)
403 : return;
404 :
405 0 : if (dl_entity_is_special(dl_se))
406 : return;
407 :
408 0 : WARN_ON(dl_se->dl_non_contending);
409 :
410 0 : zerolag_time = dl_se->deadline -
411 0 : div64_long((dl_se->runtime * dl_se->dl_period),
412 : dl_se->dl_runtime);
413 :
414 : /*
415 : * Using relative times instead of the absolute "0-lag time"
416 : * allows to simplify the code
417 : */
418 0 : zerolag_time -= rq_clock(rq);
419 :
420 : /*
421 : * If the "0-lag time" already passed, decrease the active
422 : * utilization now, instead of starting a timer
423 : */
424 0 : if ((zerolag_time < 0) || hrtimer_active(&dl_se->inactive_timer)) {
425 0 : if (dl_task(p))
426 0 : sub_running_bw(dl_se, dl_rq);
427 0 : if (!dl_task(p) || READ_ONCE(p->__state) == TASK_DEAD) {
428 0 : struct dl_bw *dl_b = dl_bw_of(task_cpu(p));
429 :
430 0 : if (READ_ONCE(p->__state) == TASK_DEAD)
431 0 : sub_rq_bw(&p->dl, &rq->dl);
432 0 : raw_spin_lock(&dl_b->lock);
433 0 : __dl_sub(dl_b, p->dl.dl_bw, dl_bw_cpus(task_cpu(p)));
434 0 : raw_spin_unlock(&dl_b->lock);
435 : __dl_clear_params(p);
436 : }
437 :
438 : return;
439 : }
440 :
441 0 : dl_se->dl_non_contending = 1;
442 0 : get_task_struct(p);
443 0 : hrtimer_start(timer, ns_to_ktime(zerolag_time), HRTIMER_MODE_REL_HARD);
444 : }
445 :
446 0 : static void task_contending(struct sched_dl_entity *dl_se, int flags)
447 : {
448 0 : struct dl_rq *dl_rq = dl_rq_of_se(dl_se);
449 :
450 : /*
451 : * If this is a non-deadline task that has been boosted,
452 : * do nothing
453 : */
454 0 : if (dl_se->dl_runtime == 0)
455 : return;
456 :
457 : if (flags & ENQUEUE_MIGRATED)
458 : add_rq_bw(dl_se, dl_rq);
459 :
460 0 : if (dl_se->dl_non_contending) {
461 0 : dl_se->dl_non_contending = 0;
462 : /*
463 : * If the timer handler is currently running and the
464 : * timer cannot be canceled, inactive_task_timer()
465 : * will see that dl_not_contending is not set, and
466 : * will not touch the rq's active utilization,
467 : * so we are still safe.
468 : */
469 0 : if (hrtimer_try_to_cancel(&dl_se->inactive_timer) == 1)
470 0 : put_task_struct(dl_task_of(dl_se));
471 : } else {
472 : /*
473 : * Since "dl_non_contending" is not set, the
474 : * task's utilization has already been removed from
475 : * active utilization (either when the task blocked,
476 : * when the "inactive timer" fired).
477 : * So, add it back.
478 : */
479 0 : add_running_bw(dl_se, dl_rq);
480 : }
481 : }
482 :
483 : static inline int is_leftmost(struct task_struct *p, struct dl_rq *dl_rq)
484 : {
485 0 : struct sched_dl_entity *dl_se = &p->dl;
486 :
487 : return rb_first_cached(&dl_rq->root) == &dl_se->rb_node;
488 : }
489 :
490 : static void init_dl_rq_bw_ratio(struct dl_rq *dl_rq);
491 :
492 0 : void init_dl_bandwidth(struct dl_bandwidth *dl_b, u64 period, u64 runtime)
493 : {
494 : raw_spin_lock_init(&dl_b->dl_runtime_lock);
495 0 : dl_b->dl_period = period;
496 0 : dl_b->dl_runtime = runtime;
497 0 : }
498 :
499 1 : void init_dl_bw(struct dl_bw *dl_b)
500 : {
501 : raw_spin_lock_init(&dl_b->lock);
502 1 : if (global_rt_runtime() == RUNTIME_INF)
503 0 : dl_b->bw = -1;
504 : else
505 1 : dl_b->bw = to_ratio(global_rt_period(), global_rt_runtime());
506 1 : dl_b->total_bw = 0;
507 1 : }
508 :
509 1 : void init_dl_rq(struct dl_rq *dl_rq)
510 : {
511 1 : dl_rq->root = RB_ROOT_CACHED;
512 :
513 : #ifdef CONFIG_SMP
514 : /* zero means no -deadline tasks */
515 : dl_rq->earliest_dl.curr = dl_rq->earliest_dl.next = 0;
516 :
517 : dl_rq->dl_nr_migratory = 0;
518 : dl_rq->overloaded = 0;
519 : dl_rq->pushable_dl_tasks_root = RB_ROOT_CACHED;
520 : #else
521 1 : init_dl_bw(&dl_rq->dl_bw);
522 : #endif
523 :
524 1 : dl_rq->running_bw = 0;
525 1 : dl_rq->this_bw = 0;
526 1 : init_dl_rq_bw_ratio(dl_rq);
527 1 : }
528 :
529 : #ifdef CONFIG_SMP
530 :
531 : static inline int dl_overloaded(struct rq *rq)
532 : {
533 : return atomic_read(&rq->rd->dlo_count);
534 : }
535 :
536 : static inline void dl_set_overload(struct rq *rq)
537 : {
538 : if (!rq->online)
539 : return;
540 :
541 : cpumask_set_cpu(rq->cpu, rq->rd->dlo_mask);
542 : /*
543 : * Must be visible before the overload count is
544 : * set (as in sched_rt.c).
545 : *
546 : * Matched by the barrier in pull_dl_task().
547 : */
548 : smp_wmb();
549 : atomic_inc(&rq->rd->dlo_count);
550 : }
551 :
552 : static inline void dl_clear_overload(struct rq *rq)
553 : {
554 : if (!rq->online)
555 : return;
556 :
557 : atomic_dec(&rq->rd->dlo_count);
558 : cpumask_clear_cpu(rq->cpu, rq->rd->dlo_mask);
559 : }
560 :
561 : static void update_dl_migration(struct dl_rq *dl_rq)
562 : {
563 : if (dl_rq->dl_nr_migratory && dl_rq->dl_nr_running > 1) {
564 : if (!dl_rq->overloaded) {
565 : dl_set_overload(rq_of_dl_rq(dl_rq));
566 : dl_rq->overloaded = 1;
567 : }
568 : } else if (dl_rq->overloaded) {
569 : dl_clear_overload(rq_of_dl_rq(dl_rq));
570 : dl_rq->overloaded = 0;
571 : }
572 : }
573 :
574 : static void inc_dl_migration(struct sched_dl_entity *dl_se, struct dl_rq *dl_rq)
575 : {
576 : struct task_struct *p = dl_task_of(dl_se);
577 :
578 : if (p->nr_cpus_allowed > 1)
579 : dl_rq->dl_nr_migratory++;
580 :
581 : update_dl_migration(dl_rq);
582 : }
583 :
584 : static void dec_dl_migration(struct sched_dl_entity *dl_se, struct dl_rq *dl_rq)
585 : {
586 : struct task_struct *p = dl_task_of(dl_se);
587 :
588 : if (p->nr_cpus_allowed > 1)
589 : dl_rq->dl_nr_migratory--;
590 :
591 : update_dl_migration(dl_rq);
592 : }
593 :
594 : #define __node_2_pdl(node) \
595 : rb_entry((node), struct task_struct, pushable_dl_tasks)
596 :
597 : static inline bool __pushable_less(struct rb_node *a, const struct rb_node *b)
598 : {
599 : return dl_entity_preempt(&__node_2_pdl(a)->dl, &__node_2_pdl(b)->dl);
600 : }
601 :
602 : /*
603 : * The list of pushable -deadline task is not a plist, like in
604 : * sched_rt.c, it is an rb-tree with tasks ordered by deadline.
605 : */
606 : static void enqueue_pushable_dl_task(struct rq *rq, struct task_struct *p)
607 : {
608 : struct rb_node *leftmost;
609 :
610 : WARN_ON_ONCE(!RB_EMPTY_NODE(&p->pushable_dl_tasks));
611 :
612 : leftmost = rb_add_cached(&p->pushable_dl_tasks,
613 : &rq->dl.pushable_dl_tasks_root,
614 : __pushable_less);
615 : if (leftmost)
616 : rq->dl.earliest_dl.next = p->dl.deadline;
617 : }
618 :
619 : static void dequeue_pushable_dl_task(struct rq *rq, struct task_struct *p)
620 : {
621 : struct dl_rq *dl_rq = &rq->dl;
622 : struct rb_root_cached *root = &dl_rq->pushable_dl_tasks_root;
623 : struct rb_node *leftmost;
624 :
625 : if (RB_EMPTY_NODE(&p->pushable_dl_tasks))
626 : return;
627 :
628 : leftmost = rb_erase_cached(&p->pushable_dl_tasks, root);
629 : if (leftmost)
630 : dl_rq->earliest_dl.next = __node_2_pdl(leftmost)->dl.deadline;
631 :
632 : RB_CLEAR_NODE(&p->pushable_dl_tasks);
633 : }
634 :
635 : static inline int has_pushable_dl_tasks(struct rq *rq)
636 : {
637 : return !RB_EMPTY_ROOT(&rq->dl.pushable_dl_tasks_root.rb_root);
638 : }
639 :
640 : static int push_dl_task(struct rq *rq);
641 :
642 : static inline bool need_pull_dl_task(struct rq *rq, struct task_struct *prev)
643 : {
644 : return rq->online && dl_task(prev);
645 : }
646 :
647 : static DEFINE_PER_CPU(struct balance_callback, dl_push_head);
648 : static DEFINE_PER_CPU(struct balance_callback, dl_pull_head);
649 :
650 : static void push_dl_tasks(struct rq *);
651 : static void pull_dl_task(struct rq *);
652 :
653 : static inline void deadline_queue_push_tasks(struct rq *rq)
654 : {
655 : if (!has_pushable_dl_tasks(rq))
656 : return;
657 :
658 : queue_balance_callback(rq, &per_cpu(dl_push_head, rq->cpu), push_dl_tasks);
659 : }
660 :
661 : static inline void deadline_queue_pull_task(struct rq *rq)
662 : {
663 : queue_balance_callback(rq, &per_cpu(dl_pull_head, rq->cpu), pull_dl_task);
664 : }
665 :
666 : static struct rq *find_lock_later_rq(struct task_struct *task, struct rq *rq);
667 :
668 : static struct rq *dl_task_offline_migration(struct rq *rq, struct task_struct *p)
669 : {
670 : struct rq *later_rq = NULL;
671 : struct dl_bw *dl_b;
672 :
673 : later_rq = find_lock_later_rq(p, rq);
674 : if (!later_rq) {
675 : int cpu;
676 :
677 : /*
678 : * If we cannot preempt any rq, fall back to pick any
679 : * online CPU:
680 : */
681 : cpu = cpumask_any_and(cpu_active_mask, p->cpus_ptr);
682 : if (cpu >= nr_cpu_ids) {
683 : /*
684 : * Failed to find any suitable CPU.
685 : * The task will never come back!
686 : */
687 : WARN_ON_ONCE(dl_bandwidth_enabled());
688 :
689 : /*
690 : * If admission control is disabled we
691 : * try a little harder to let the task
692 : * run.
693 : */
694 : cpu = cpumask_any(cpu_active_mask);
695 : }
696 : later_rq = cpu_rq(cpu);
697 : double_lock_balance(rq, later_rq);
698 : }
699 :
700 : if (p->dl.dl_non_contending || p->dl.dl_throttled) {
701 : /*
702 : * Inactive timer is armed (or callback is running, but
703 : * waiting for us to release rq locks). In any case, when it
704 : * will fire (or continue), it will see running_bw of this
705 : * task migrated to later_rq (and correctly handle it).
706 : */
707 : sub_running_bw(&p->dl, &rq->dl);
708 : sub_rq_bw(&p->dl, &rq->dl);
709 :
710 : add_rq_bw(&p->dl, &later_rq->dl);
711 : add_running_bw(&p->dl, &later_rq->dl);
712 : } else {
713 : sub_rq_bw(&p->dl, &rq->dl);
714 : add_rq_bw(&p->dl, &later_rq->dl);
715 : }
716 :
717 : /*
718 : * And we finally need to fixup root_domain(s) bandwidth accounting,
719 : * since p is still hanging out in the old (now moved to default) root
720 : * domain.
721 : */
722 : dl_b = &rq->rd->dl_bw;
723 : raw_spin_lock(&dl_b->lock);
724 : __dl_sub(dl_b, p->dl.dl_bw, cpumask_weight(rq->rd->span));
725 : raw_spin_unlock(&dl_b->lock);
726 :
727 : dl_b = &later_rq->rd->dl_bw;
728 : raw_spin_lock(&dl_b->lock);
729 : __dl_add(dl_b, p->dl.dl_bw, cpumask_weight(later_rq->rd->span));
730 : raw_spin_unlock(&dl_b->lock);
731 :
732 : set_task_cpu(p, later_rq->cpu);
733 : double_unlock_balance(later_rq, rq);
734 :
735 : return later_rq;
736 : }
737 :
738 : #else
739 :
740 : static inline
741 : void enqueue_pushable_dl_task(struct rq *rq, struct task_struct *p)
742 : {
743 : }
744 :
745 : static inline
746 : void dequeue_pushable_dl_task(struct rq *rq, struct task_struct *p)
747 : {
748 : }
749 :
750 : static inline
751 : void inc_dl_migration(struct sched_dl_entity *dl_se, struct dl_rq *dl_rq)
752 : {
753 : }
754 :
755 : static inline
756 : void dec_dl_migration(struct sched_dl_entity *dl_se, struct dl_rq *dl_rq)
757 : {
758 : }
759 :
760 : static inline void deadline_queue_push_tasks(struct rq *rq)
761 : {
762 : }
763 :
764 : static inline void deadline_queue_pull_task(struct rq *rq)
765 : {
766 : }
767 : #endif /* CONFIG_SMP */
768 :
769 : static void enqueue_task_dl(struct rq *rq, struct task_struct *p, int flags);
770 : static void __dequeue_task_dl(struct rq *rq, struct task_struct *p, int flags);
771 : static void check_preempt_curr_dl(struct rq *rq, struct task_struct *p, int flags);
772 :
773 : static inline void replenish_dl_new_period(struct sched_dl_entity *dl_se,
774 : struct rq *rq)
775 : {
776 : /* for non-boosted task, pi_of(dl_se) == dl_se */
777 0 : dl_se->deadline = rq_clock(rq) + pi_of(dl_se)->dl_deadline;
778 0 : dl_se->runtime = pi_of(dl_se)->dl_runtime;
779 : }
780 :
781 : /*
782 : * We are being explicitly informed that a new instance is starting,
783 : * and this means that:
784 : * - the absolute deadline of the entity has to be placed at
785 : * current time + relative deadline;
786 : * - the runtime of the entity has to be set to the maximum value.
787 : *
788 : * The capability of specifying such event is useful whenever a -deadline
789 : * entity wants to (try to!) synchronize its behaviour with the scheduler's
790 : * one, and to (try to!) reconcile itself with its own scheduling
791 : * parameters.
792 : */
793 0 : static inline void setup_new_dl_entity(struct sched_dl_entity *dl_se)
794 : {
795 0 : struct dl_rq *dl_rq = dl_rq_of_se(dl_se);
796 0 : struct rq *rq = rq_of_dl_rq(dl_rq);
797 :
798 0 : WARN_ON(is_dl_boosted(dl_se));
799 0 : WARN_ON(dl_time_before(rq_clock(rq), dl_se->deadline));
800 :
801 : /*
802 : * We are racing with the deadline timer. So, do nothing because
803 : * the deadline timer handler will take care of properly recharging
804 : * the runtime and postponing the deadline
805 : */
806 0 : if (dl_se->dl_throttled)
807 : return;
808 :
809 : /*
810 : * We use the regular wall clock time to set deadlines in the
811 : * future; in fact, we must consider execution overheads (time
812 : * spent on hardirq context, etc.).
813 : */
814 : replenish_dl_new_period(dl_se, rq);
815 : }
816 :
817 : /*
818 : * Pure Earliest Deadline First (EDF) scheduling does not deal with the
819 : * possibility of a entity lasting more than what it declared, and thus
820 : * exhausting its runtime.
821 : *
822 : * Here we are interested in making runtime overrun possible, but we do
823 : * not want a entity which is misbehaving to affect the scheduling of all
824 : * other entities.
825 : * Therefore, a budgeting strategy called Constant Bandwidth Server (CBS)
826 : * is used, in order to confine each entity within its own bandwidth.
827 : *
828 : * This function deals exactly with that, and ensures that when the runtime
829 : * of a entity is replenished, its deadline is also postponed. That ensures
830 : * the overrunning entity can't interfere with other entity in the system and
831 : * can't make them miss their deadlines. Reasons why this kind of overruns
832 : * could happen are, typically, a entity voluntarily trying to overcome its
833 : * runtime, or it just underestimated it during sched_setattr().
834 : */
835 0 : static void replenish_dl_entity(struct sched_dl_entity *dl_se)
836 : {
837 0 : struct dl_rq *dl_rq = dl_rq_of_se(dl_se);
838 0 : struct rq *rq = rq_of_dl_rq(dl_rq);
839 :
840 0 : WARN_ON_ONCE(pi_of(dl_se)->dl_runtime <= 0);
841 :
842 : /*
843 : * This could be the case for a !-dl task that is boosted.
844 : * Just go with full inherited parameters.
845 : */
846 0 : if (dl_se->dl_deadline == 0)
847 : replenish_dl_new_period(dl_se, rq);
848 :
849 0 : if (dl_se->dl_yielded && dl_se->runtime > 0)
850 0 : dl_se->runtime = 0;
851 :
852 : /*
853 : * We keep moving the deadline away until we get some
854 : * available runtime for the entity. This ensures correct
855 : * handling of situations where the runtime overrun is
856 : * arbitrary large.
857 : */
858 0 : while (dl_se->runtime <= 0) {
859 0 : dl_se->deadline += pi_of(dl_se)->dl_period;
860 0 : dl_se->runtime += pi_of(dl_se)->dl_runtime;
861 : }
862 :
863 : /*
864 : * At this point, the deadline really should be "in
865 : * the future" with respect to rq->clock. If it's
866 : * not, we are, for some reason, lagging too much!
867 : * Anyway, after having warn userspace abut that,
868 : * we still try to keep the things running by
869 : * resetting the deadline and the budget of the
870 : * entity.
871 : */
872 0 : if (dl_time_before(dl_se->deadline, rq_clock(rq))) {
873 0 : printk_deferred_once("sched: DL replenish lagged too much\n");
874 : replenish_dl_new_period(dl_se, rq);
875 : }
876 :
877 0 : if (dl_se->dl_yielded)
878 0 : dl_se->dl_yielded = 0;
879 0 : if (dl_se->dl_throttled)
880 0 : dl_se->dl_throttled = 0;
881 0 : }
882 :
883 : /*
884 : * Here we check if --at time t-- an entity (which is probably being
885 : * [re]activated or, in general, enqueued) can use its remaining runtime
886 : * and its current deadline _without_ exceeding the bandwidth it is
887 : * assigned (function returns true if it can't). We are in fact applying
888 : * one of the CBS rules: when a task wakes up, if the residual runtime
889 : * over residual deadline fits within the allocated bandwidth, then we
890 : * can keep the current (absolute) deadline and residual budget without
891 : * disrupting the schedulability of the system. Otherwise, we should
892 : * refill the runtime and set the deadline a period in the future,
893 : * because keeping the current (absolute) deadline of the task would
894 : * result in breaking guarantees promised to other tasks (refer to
895 : * Documentation/scheduler/sched-deadline.rst for more information).
896 : *
897 : * This function returns true if:
898 : *
899 : * runtime / (deadline - t) > dl_runtime / dl_deadline ,
900 : *
901 : * IOW we can't recycle current parameters.
902 : *
903 : * Notice that the bandwidth check is done against the deadline. For
904 : * task with deadline equal to period this is the same of using
905 : * dl_period instead of dl_deadline in the equation above.
906 : */
907 : static bool dl_entity_overflow(struct sched_dl_entity *dl_se, u64 t)
908 : {
909 : u64 left, right;
910 :
911 : /*
912 : * left and right are the two sides of the equation above,
913 : * after a bit of shuffling to use multiplications instead
914 : * of divisions.
915 : *
916 : * Note that none of the time values involved in the two
917 : * multiplications are absolute: dl_deadline and dl_runtime
918 : * are the relative deadline and the maximum runtime of each
919 : * instance, runtime is the runtime left for the last instance
920 : * and (deadline - t), since t is rq->clock, is the time left
921 : * to the (absolute) deadline. Even if overflowing the u64 type
922 : * is very unlikely to occur in both cases, here we scale down
923 : * as we want to avoid that risk at all. Scaling down by 10
924 : * means that we reduce granularity to 1us. We are fine with it,
925 : * since this is only a true/false check and, anyway, thinking
926 : * of anything below microseconds resolution is actually fiction
927 : * (but still we want to give the user that illusion >;).
928 : */
929 0 : left = (pi_of(dl_se)->dl_deadline >> DL_SCALE) * (dl_se->runtime >> DL_SCALE);
930 0 : right = ((dl_se->deadline - t) >> DL_SCALE) *
931 0 : (pi_of(dl_se)->dl_runtime >> DL_SCALE);
932 :
933 0 : return dl_time_before(right, left);
934 : }
935 :
936 : /*
937 : * Revised wakeup rule [1]: For self-suspending tasks, rather then
938 : * re-initializing task's runtime and deadline, the revised wakeup
939 : * rule adjusts the task's runtime to avoid the task to overrun its
940 : * density.
941 : *
942 : * Reasoning: a task may overrun the density if:
943 : * runtime / (deadline - t) > dl_runtime / dl_deadline
944 : *
945 : * Therefore, runtime can be adjusted to:
946 : * runtime = (dl_runtime / dl_deadline) * (deadline - t)
947 : *
948 : * In such way that runtime will be equal to the maximum density
949 : * the task can use without breaking any rule.
950 : *
951 : * [1] Luca Abeni, Giuseppe Lipari, and Juri Lelli. 2015. Constant
952 : * bandwidth server revisited. SIGBED Rev. 11, 4 (January 2015), 19-24.
953 : */
954 : static void
955 0 : update_dl_revised_wakeup(struct sched_dl_entity *dl_se, struct rq *rq)
956 : {
957 0 : u64 laxity = dl_se->deadline - rq_clock(rq);
958 :
959 : /*
960 : * If the task has deadline < period, and the deadline is in the past,
961 : * it should already be throttled before this check.
962 : *
963 : * See update_dl_entity() comments for further details.
964 : */
965 0 : WARN_ON(dl_time_before(dl_se->deadline, rq_clock(rq)));
966 :
967 0 : dl_se->runtime = (dl_se->dl_density * laxity) >> BW_SHIFT;
968 0 : }
969 :
970 : /*
971 : * Regarding the deadline, a task with implicit deadline has a relative
972 : * deadline == relative period. A task with constrained deadline has a
973 : * relative deadline <= relative period.
974 : *
975 : * We support constrained deadline tasks. However, there are some restrictions
976 : * applied only for tasks which do not have an implicit deadline. See
977 : * update_dl_entity() to know more about such restrictions.
978 : *
979 : * The dl_is_implicit() returns true if the task has an implicit deadline.
980 : */
981 : static inline bool dl_is_implicit(struct sched_dl_entity *dl_se)
982 : {
983 : return dl_se->dl_deadline == dl_se->dl_period;
984 : }
985 :
986 : /*
987 : * When a deadline entity is placed in the runqueue, its runtime and deadline
988 : * might need to be updated. This is done by a CBS wake up rule. There are two
989 : * different rules: 1) the original CBS; and 2) the Revisited CBS.
990 : *
991 : * When the task is starting a new period, the Original CBS is used. In this
992 : * case, the runtime is replenished and a new absolute deadline is set.
993 : *
994 : * When a task is queued before the begin of the next period, using the
995 : * remaining runtime and deadline could make the entity to overflow, see
996 : * dl_entity_overflow() to find more about runtime overflow. When such case
997 : * is detected, the runtime and deadline need to be updated.
998 : *
999 : * If the task has an implicit deadline, i.e., deadline == period, the Original
1000 : * CBS is applied. the runtime is replenished and a new absolute deadline is
1001 : * set, as in the previous cases.
1002 : *
1003 : * However, the Original CBS does not work properly for tasks with
1004 : * deadline < period, which are said to have a constrained deadline. By
1005 : * applying the Original CBS, a constrained deadline task would be able to run
1006 : * runtime/deadline in a period. With deadline < period, the task would
1007 : * overrun the runtime/period allowed bandwidth, breaking the admission test.
1008 : *
1009 : * In order to prevent this misbehave, the Revisited CBS is used for
1010 : * constrained deadline tasks when a runtime overflow is detected. In the
1011 : * Revisited CBS, rather than replenishing & setting a new absolute deadline,
1012 : * the remaining runtime of the task is reduced to avoid runtime overflow.
1013 : * Please refer to the comments update_dl_revised_wakeup() function to find
1014 : * more about the Revised CBS rule.
1015 : */
1016 0 : static void update_dl_entity(struct sched_dl_entity *dl_se)
1017 : {
1018 0 : struct dl_rq *dl_rq = dl_rq_of_se(dl_se);
1019 0 : struct rq *rq = rq_of_dl_rq(dl_rq);
1020 :
1021 0 : if (dl_time_before(dl_se->deadline, rq_clock(rq)) ||
1022 0 : dl_entity_overflow(dl_se, rq_clock(rq))) {
1023 :
1024 0 : if (unlikely(!dl_is_implicit(dl_se) &&
1025 : !dl_time_before(dl_se->deadline, rq_clock(rq)) &&
1026 : !is_dl_boosted(dl_se))) {
1027 0 : update_dl_revised_wakeup(dl_se, rq);
1028 0 : return;
1029 : }
1030 :
1031 : replenish_dl_new_period(dl_se, rq);
1032 : }
1033 : }
1034 :
1035 : static inline u64 dl_next_period(struct sched_dl_entity *dl_se)
1036 : {
1037 0 : return dl_se->deadline - dl_se->dl_deadline + dl_se->dl_period;
1038 : }
1039 :
1040 : /*
1041 : * If the entity depleted all its runtime, and if we want it to sleep
1042 : * while waiting for some new execution time to become available, we
1043 : * set the bandwidth replenishment timer to the replenishment instant
1044 : * and try to activate it.
1045 : *
1046 : * Notice that it is important for the caller to know if the timer
1047 : * actually started or not (i.e., the replenishment instant is in
1048 : * the future or in the past).
1049 : */
1050 0 : static int start_dl_timer(struct task_struct *p)
1051 : {
1052 0 : struct sched_dl_entity *dl_se = &p->dl;
1053 0 : struct hrtimer *timer = &dl_se->dl_timer;
1054 0 : struct rq *rq = task_rq(p);
1055 : ktime_t now, act;
1056 : s64 delta;
1057 :
1058 0 : lockdep_assert_rq_held(rq);
1059 :
1060 : /*
1061 : * We want the timer to fire at the deadline, but considering
1062 : * that it is actually coming from rq->clock and not from
1063 : * hrtimer's time base reading.
1064 : */
1065 0 : act = ns_to_ktime(dl_next_period(dl_se));
1066 0 : now = hrtimer_cb_get_time(timer);
1067 0 : delta = ktime_to_ns(now) - rq_clock(rq);
1068 0 : act = ktime_add_ns(act, delta);
1069 :
1070 : /*
1071 : * If the expiry time already passed, e.g., because the value
1072 : * chosen as the deadline is too small, don't even try to
1073 : * start the timer in the past!
1074 : */
1075 0 : if (ktime_us_delta(act, now) < 0)
1076 : return 0;
1077 :
1078 : /*
1079 : * !enqueued will guarantee another callback; even if one is already in
1080 : * progress. This ensures a balanced {get,put}_task_struct().
1081 : *
1082 : * The race against __run_timer() clearing the enqueued state is
1083 : * harmless because we're holding task_rq()->lock, therefore the timer
1084 : * expiring after we've done the check will wait on its task_rq_lock()
1085 : * and observe our state.
1086 : */
1087 0 : if (!hrtimer_is_queued(timer)) {
1088 0 : get_task_struct(p);
1089 : hrtimer_start(timer, act, HRTIMER_MODE_ABS_HARD);
1090 : }
1091 :
1092 : return 1;
1093 : }
1094 :
1095 : /*
1096 : * This is the bandwidth enforcement timer callback. If here, we know
1097 : * a task is not on its dl_rq, since the fact that the timer was running
1098 : * means the task is throttled and needs a runtime replenishment.
1099 : *
1100 : * However, what we actually do depends on the fact the task is active,
1101 : * (it is on its rq) or has been removed from there by a call to
1102 : * dequeue_task_dl(). In the former case we must issue the runtime
1103 : * replenishment and add the task back to the dl_rq; in the latter, we just
1104 : * do nothing but clearing dl_throttled, so that runtime and deadline
1105 : * updating (and the queueing back to dl_rq) will be done by the
1106 : * next call to enqueue_task_dl().
1107 : */
1108 0 : static enum hrtimer_restart dl_task_timer(struct hrtimer *timer)
1109 : {
1110 0 : struct sched_dl_entity *dl_se = container_of(timer,
1111 : struct sched_dl_entity,
1112 : dl_timer);
1113 0 : struct task_struct *p = dl_task_of(dl_se);
1114 : struct rq_flags rf;
1115 : struct rq *rq;
1116 :
1117 0 : rq = task_rq_lock(p, &rf);
1118 :
1119 : /*
1120 : * The task might have changed its scheduling policy to something
1121 : * different than SCHED_DEADLINE (through switched_from_dl()).
1122 : */
1123 0 : if (!dl_task(p))
1124 : goto unlock;
1125 :
1126 : /*
1127 : * The task might have been boosted by someone else and might be in the
1128 : * boosting/deboosting path, its not throttled.
1129 : */
1130 0 : if (is_dl_boosted(dl_se))
1131 : goto unlock;
1132 :
1133 : /*
1134 : * Spurious timer due to start_dl_timer() race; or we already received
1135 : * a replenishment from rt_mutex_setprio().
1136 : */
1137 0 : if (!dl_se->dl_throttled)
1138 : goto unlock;
1139 :
1140 : sched_clock_tick();
1141 0 : update_rq_clock(rq);
1142 :
1143 : /*
1144 : * If the throttle happened during sched-out; like:
1145 : *
1146 : * schedule()
1147 : * deactivate_task()
1148 : * dequeue_task_dl()
1149 : * update_curr_dl()
1150 : * start_dl_timer()
1151 : * __dequeue_task_dl()
1152 : * prev->on_rq = 0;
1153 : *
1154 : * We can be both throttled and !queued. Replenish the counter
1155 : * but do not enqueue -- wait for our wakeup to do that.
1156 : */
1157 0 : if (!task_on_rq_queued(p)) {
1158 0 : replenish_dl_entity(dl_se);
1159 0 : goto unlock;
1160 : }
1161 :
1162 : #ifdef CONFIG_SMP
1163 : if (unlikely(!rq->online)) {
1164 : /*
1165 : * If the runqueue is no longer available, migrate the
1166 : * task elsewhere. This necessarily changes rq.
1167 : */
1168 : lockdep_unpin_lock(__rq_lockp(rq), rf.cookie);
1169 : rq = dl_task_offline_migration(rq, p);
1170 : rf.cookie = lockdep_pin_lock(__rq_lockp(rq));
1171 : update_rq_clock(rq);
1172 :
1173 : /*
1174 : * Now that the task has been migrated to the new RQ and we
1175 : * have that locked, proceed as normal and enqueue the task
1176 : * there.
1177 : */
1178 : }
1179 : #endif
1180 :
1181 0 : enqueue_task_dl(rq, p, ENQUEUE_REPLENISH);
1182 0 : if (dl_task(rq->curr))
1183 : check_preempt_curr_dl(rq, p, 0);
1184 : else
1185 0 : resched_curr(rq);
1186 :
1187 : #ifdef CONFIG_SMP
1188 : /*
1189 : * Queueing this task back might have overloaded rq, check if we need
1190 : * to kick someone away.
1191 : */
1192 : if (has_pushable_dl_tasks(rq)) {
1193 : /*
1194 : * Nothing relies on rq->lock after this, so its safe to drop
1195 : * rq->lock.
1196 : */
1197 : rq_unpin_lock(rq, &rf);
1198 : push_dl_task(rq);
1199 : rq_repin_lock(rq, &rf);
1200 : }
1201 : #endif
1202 :
1203 : unlock:
1204 0 : task_rq_unlock(rq, p, &rf);
1205 :
1206 : /*
1207 : * This can free the task_struct, including this hrtimer, do not touch
1208 : * anything related to that after this.
1209 : */
1210 0 : put_task_struct(p);
1211 :
1212 0 : return HRTIMER_NORESTART;
1213 : }
1214 :
1215 349 : void init_dl_task_timer(struct sched_dl_entity *dl_se)
1216 : {
1217 349 : struct hrtimer *timer = &dl_se->dl_timer;
1218 :
1219 349 : hrtimer_init(timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL_HARD);
1220 349 : timer->function = dl_task_timer;
1221 349 : }
1222 :
1223 : /*
1224 : * During the activation, CBS checks if it can reuse the current task's
1225 : * runtime and period. If the deadline of the task is in the past, CBS
1226 : * cannot use the runtime, and so it replenishes the task. This rule
1227 : * works fine for implicit deadline tasks (deadline == period), and the
1228 : * CBS was designed for implicit deadline tasks. However, a task with
1229 : * constrained deadline (deadline < period) might be awakened after the
1230 : * deadline, but before the next period. In this case, replenishing the
1231 : * task would allow it to run for runtime / deadline. As in this case
1232 : * deadline < period, CBS enables a task to run for more than the
1233 : * runtime / period. In a very loaded system, this can cause a domino
1234 : * effect, making other tasks miss their deadlines.
1235 : *
1236 : * To avoid this problem, in the activation of a constrained deadline
1237 : * task after the deadline but before the next period, throttle the
1238 : * task and set the replenishing timer to the begin of the next period,
1239 : * unless it is boosted.
1240 : */
1241 0 : static inline void dl_check_constrained_dl(struct sched_dl_entity *dl_se)
1242 : {
1243 0 : struct task_struct *p = dl_task_of(dl_se);
1244 0 : struct rq *rq = rq_of_dl_rq(dl_rq_of_se(dl_se));
1245 :
1246 0 : if (dl_time_before(dl_se->deadline, rq_clock(rq)) &&
1247 0 : dl_time_before(rq_clock(rq), dl_next_period(dl_se))) {
1248 0 : if (unlikely(is_dl_boosted(dl_se) || !start_dl_timer(p)))
1249 : return;
1250 0 : dl_se->dl_throttled = 1;
1251 0 : if (dl_se->runtime > 0)
1252 0 : dl_se->runtime = 0;
1253 : }
1254 : }
1255 :
1256 : static
1257 : int dl_runtime_exceeded(struct sched_dl_entity *dl_se)
1258 : {
1259 : return (dl_se->runtime <= 0);
1260 : }
1261 :
1262 : /*
1263 : * This function implements the GRUB accounting rule:
1264 : * according to the GRUB reclaiming algorithm, the runtime is
1265 : * not decreased as "dq = -dt", but as
1266 : * "dq = -max{u / Umax, (1 - Uinact - Uextra)} dt",
1267 : * where u is the utilization of the task, Umax is the maximum reclaimable
1268 : * utilization, Uinact is the (per-runqueue) inactive utilization, computed
1269 : * as the difference between the "total runqueue utilization" and the
1270 : * runqueue active utilization, and Uextra is the (per runqueue) extra
1271 : * reclaimable utilization.
1272 : * Since rq->dl.running_bw and rq->dl.this_bw contain utilizations
1273 : * multiplied by 2^BW_SHIFT, the result has to be shifted right by
1274 : * BW_SHIFT.
1275 : * Since rq->dl.bw_ratio contains 1 / Umax multiplied by 2^RATIO_SHIFT,
1276 : * dl_bw is multiped by rq->dl.bw_ratio and shifted right by RATIO_SHIFT.
1277 : * Since delta is a 64 bit variable, to have an overflow its value
1278 : * should be larger than 2^(64 - 20 - 8), which is more than 64 seconds.
1279 : * So, overflow is not an issue here.
1280 : */
1281 : static u64 grub_reclaim(u64 delta, struct rq *rq, struct sched_dl_entity *dl_se)
1282 : {
1283 0 : u64 u_inact = rq->dl.this_bw - rq->dl.running_bw; /* Utot - Uact */
1284 : u64 u_act;
1285 0 : u64 u_act_min = (dl_se->dl_bw * rq->dl.bw_ratio) >> RATIO_SHIFT;
1286 :
1287 : /*
1288 : * Instead of computing max{u * bw_ratio, (1 - u_inact - u_extra)},
1289 : * we compare u_inact + rq->dl.extra_bw with
1290 : * 1 - (u * rq->dl.bw_ratio >> RATIO_SHIFT), because
1291 : * u_inact + rq->dl.extra_bw can be larger than
1292 : * 1 * (so, 1 - u_inact - rq->dl.extra_bw would be negative
1293 : * leading to wrong results)
1294 : */
1295 0 : if (u_inact + rq->dl.extra_bw > BW_UNIT - u_act_min)
1296 : u_act = u_act_min;
1297 : else
1298 0 : u_act = BW_UNIT - u_inact - rq->dl.extra_bw;
1299 :
1300 0 : return (delta * u_act) >> BW_SHIFT;
1301 : }
1302 :
1303 : /*
1304 : * Update the current task's runtime statistics (provided it is still
1305 : * a -deadline task and has not been removed from the dl_rq).
1306 : */
1307 0 : static void update_curr_dl(struct rq *rq)
1308 : {
1309 0 : struct task_struct *curr = rq->curr;
1310 0 : struct sched_dl_entity *dl_se = &curr->dl;
1311 : u64 delta_exec, scaled_delta_exec;
1312 0 : int cpu = cpu_of(rq);
1313 : u64 now;
1314 :
1315 0 : if (!dl_task(curr) || !on_dl_rq(dl_se))
1316 : return;
1317 :
1318 : /*
1319 : * Consumed budget is computed considering the time as
1320 : * observed by schedulable tasks (excluding time spent
1321 : * in hardirq context, etc.). Deadlines are instead
1322 : * computed using hard walltime. This seems to be the more
1323 : * natural solution, but the full ramifications of this
1324 : * approach need further study.
1325 : */
1326 0 : now = rq_clock_task(rq);
1327 0 : delta_exec = now - curr->se.exec_start;
1328 0 : if (unlikely((s64)delta_exec <= 0)) {
1329 0 : if (unlikely(dl_se->dl_yielded))
1330 : goto throttle;
1331 : return;
1332 : }
1333 :
1334 : schedstat_set(curr->stats.exec_max,
1335 : max(curr->stats.exec_max, delta_exec));
1336 :
1337 0 : trace_sched_stat_runtime(curr, delta_exec, 0);
1338 :
1339 0 : update_current_exec_runtime(curr, now, delta_exec);
1340 :
1341 0 : if (dl_entity_is_special(dl_se))
1342 : return;
1343 :
1344 : /*
1345 : * For tasks that participate in GRUB, we implement GRUB-PA: the
1346 : * spare reclaimed bandwidth is used to clock down frequency.
1347 : *
1348 : * For the others, we still need to scale reservation parameters
1349 : * according to current frequency and CPU maximum capacity.
1350 : */
1351 0 : if (unlikely(dl_se->flags & SCHED_FLAG_RECLAIM)) {
1352 0 : scaled_delta_exec = grub_reclaim(delta_exec,
1353 : rq,
1354 : &curr->dl);
1355 : } else {
1356 0 : unsigned long scale_freq = arch_scale_freq_capacity(cpu);
1357 0 : unsigned long scale_cpu = arch_scale_cpu_capacity(cpu);
1358 :
1359 0 : scaled_delta_exec = cap_scale(delta_exec, scale_freq);
1360 0 : scaled_delta_exec = cap_scale(scaled_delta_exec, scale_cpu);
1361 : }
1362 :
1363 0 : dl_se->runtime -= scaled_delta_exec;
1364 :
1365 : throttle:
1366 0 : if (dl_runtime_exceeded(dl_se) || dl_se->dl_yielded) {
1367 0 : dl_se->dl_throttled = 1;
1368 :
1369 : /* If requested, inform the user about runtime overruns. */
1370 0 : if (dl_runtime_exceeded(dl_se) &&
1371 0 : (dl_se->flags & SCHED_FLAG_DL_OVERRUN))
1372 0 : dl_se->dl_overrun = 1;
1373 :
1374 0 : __dequeue_task_dl(rq, curr, 0);
1375 0 : if (unlikely(is_dl_boosted(dl_se) || !start_dl_timer(curr)))
1376 0 : enqueue_task_dl(rq, curr, ENQUEUE_REPLENISH);
1377 :
1378 0 : if (!is_leftmost(curr, &rq->dl))
1379 0 : resched_curr(rq);
1380 : }
1381 :
1382 : /*
1383 : * Because -- for now -- we share the rt bandwidth, we need to
1384 : * account our runtime there too, otherwise actual rt tasks
1385 : * would be able to exceed the shared quota.
1386 : *
1387 : * Account to the root rt group for now.
1388 : *
1389 : * The solution we're working towards is having the RT groups scheduled
1390 : * using deadline servers -- however there's a few nasties to figure
1391 : * out before that can happen.
1392 : */
1393 0 : if (rt_bandwidth_enabled()) {
1394 0 : struct rt_rq *rt_rq = &rq->rt;
1395 :
1396 0 : raw_spin_lock(&rt_rq->rt_runtime_lock);
1397 : /*
1398 : * We'll let actual RT tasks worry about the overflow here, we
1399 : * have our own CBS to keep us inline; only account when RT
1400 : * bandwidth is relevant.
1401 : */
1402 0 : if (sched_rt_bandwidth_account(rt_rq))
1403 0 : rt_rq->rt_time += delta_exec;
1404 0 : raw_spin_unlock(&rt_rq->rt_runtime_lock);
1405 : }
1406 : }
1407 :
1408 0 : static enum hrtimer_restart inactive_task_timer(struct hrtimer *timer)
1409 : {
1410 0 : struct sched_dl_entity *dl_se = container_of(timer,
1411 : struct sched_dl_entity,
1412 : inactive_timer);
1413 0 : struct task_struct *p = dl_task_of(dl_se);
1414 : struct rq_flags rf;
1415 : struct rq *rq;
1416 :
1417 0 : rq = task_rq_lock(p, &rf);
1418 :
1419 : sched_clock_tick();
1420 0 : update_rq_clock(rq);
1421 :
1422 0 : if (!dl_task(p) || READ_ONCE(p->__state) == TASK_DEAD) {
1423 0 : struct dl_bw *dl_b = dl_bw_of(task_cpu(p));
1424 :
1425 0 : if (READ_ONCE(p->__state) == TASK_DEAD && dl_se->dl_non_contending) {
1426 0 : sub_running_bw(&p->dl, dl_rq_of_se(&p->dl));
1427 0 : sub_rq_bw(&p->dl, dl_rq_of_se(&p->dl));
1428 0 : dl_se->dl_non_contending = 0;
1429 : }
1430 :
1431 0 : raw_spin_lock(&dl_b->lock);
1432 0 : __dl_sub(dl_b, p->dl.dl_bw, dl_bw_cpus(task_cpu(p)));
1433 0 : raw_spin_unlock(&dl_b->lock);
1434 : __dl_clear_params(p);
1435 :
1436 : goto unlock;
1437 : }
1438 0 : if (dl_se->dl_non_contending == 0)
1439 : goto unlock;
1440 :
1441 0 : sub_running_bw(dl_se, &rq->dl);
1442 0 : dl_se->dl_non_contending = 0;
1443 : unlock:
1444 0 : task_rq_unlock(rq, p, &rf);
1445 0 : put_task_struct(p);
1446 :
1447 0 : return HRTIMER_NORESTART;
1448 : }
1449 :
1450 349 : void init_dl_inactive_task_timer(struct sched_dl_entity *dl_se)
1451 : {
1452 349 : struct hrtimer *timer = &dl_se->inactive_timer;
1453 :
1454 349 : hrtimer_init(timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL_HARD);
1455 349 : timer->function = inactive_task_timer;
1456 349 : }
1457 :
1458 : #define __node_2_dle(node) \
1459 : rb_entry((node), struct sched_dl_entity, rb_node)
1460 :
1461 : #ifdef CONFIG_SMP
1462 :
1463 : static void inc_dl_deadline(struct dl_rq *dl_rq, u64 deadline)
1464 : {
1465 : struct rq *rq = rq_of_dl_rq(dl_rq);
1466 :
1467 : if (dl_rq->earliest_dl.curr == 0 ||
1468 : dl_time_before(deadline, dl_rq->earliest_dl.curr)) {
1469 : if (dl_rq->earliest_dl.curr == 0)
1470 : cpupri_set(&rq->rd->cpupri, rq->cpu, CPUPRI_HIGHER);
1471 : dl_rq->earliest_dl.curr = deadline;
1472 : cpudl_set(&rq->rd->cpudl, rq->cpu, deadline);
1473 : }
1474 : }
1475 :
1476 : static void dec_dl_deadline(struct dl_rq *dl_rq, u64 deadline)
1477 : {
1478 : struct rq *rq = rq_of_dl_rq(dl_rq);
1479 :
1480 : /*
1481 : * Since we may have removed our earliest (and/or next earliest)
1482 : * task we must recompute them.
1483 : */
1484 : if (!dl_rq->dl_nr_running) {
1485 : dl_rq->earliest_dl.curr = 0;
1486 : dl_rq->earliest_dl.next = 0;
1487 : cpudl_clear(&rq->rd->cpudl, rq->cpu);
1488 : cpupri_set(&rq->rd->cpupri, rq->cpu, rq->rt.highest_prio.curr);
1489 : } else {
1490 : struct rb_node *leftmost = rb_first_cached(&dl_rq->root);
1491 : struct sched_dl_entity *entry = __node_2_dle(leftmost);
1492 :
1493 : dl_rq->earliest_dl.curr = entry->deadline;
1494 : cpudl_set(&rq->rd->cpudl, rq->cpu, entry->deadline);
1495 : }
1496 : }
1497 :
1498 : #else
1499 :
1500 : static inline void inc_dl_deadline(struct dl_rq *dl_rq, u64 deadline) {}
1501 : static inline void dec_dl_deadline(struct dl_rq *dl_rq, u64 deadline) {}
1502 :
1503 : #endif /* CONFIG_SMP */
1504 :
1505 : static inline
1506 0 : void inc_dl_tasks(struct sched_dl_entity *dl_se, struct dl_rq *dl_rq)
1507 : {
1508 0 : int prio = dl_task_of(dl_se)->prio;
1509 0 : u64 deadline = dl_se->deadline;
1510 :
1511 0 : WARN_ON(!dl_prio(prio));
1512 0 : dl_rq->dl_nr_running++;
1513 0 : add_nr_running(rq_of_dl_rq(dl_rq), 1);
1514 :
1515 0 : inc_dl_deadline(dl_rq, deadline);
1516 0 : inc_dl_migration(dl_se, dl_rq);
1517 0 : }
1518 :
1519 : static inline
1520 0 : void dec_dl_tasks(struct sched_dl_entity *dl_se, struct dl_rq *dl_rq)
1521 : {
1522 0 : int prio = dl_task_of(dl_se)->prio;
1523 :
1524 0 : WARN_ON(!dl_prio(prio));
1525 0 : WARN_ON(!dl_rq->dl_nr_running);
1526 0 : dl_rq->dl_nr_running--;
1527 0 : sub_nr_running(rq_of_dl_rq(dl_rq), 1);
1528 :
1529 0 : dec_dl_deadline(dl_rq, dl_se->deadline);
1530 0 : dec_dl_migration(dl_se, dl_rq);
1531 0 : }
1532 :
1533 : static inline bool __dl_less(struct rb_node *a, const struct rb_node *b)
1534 : {
1535 0 : return dl_time_before(__node_2_dle(a)->deadline, __node_2_dle(b)->deadline);
1536 : }
1537 :
1538 : static inline struct sched_statistics *
1539 : __schedstats_from_dl_se(struct sched_dl_entity *dl_se)
1540 : {
1541 : return &dl_task_of(dl_se)->stats;
1542 : }
1543 :
1544 : static inline void
1545 : update_stats_wait_start_dl(struct dl_rq *dl_rq, struct sched_dl_entity *dl_se)
1546 : {
1547 : struct sched_statistics *stats;
1548 :
1549 : if (!schedstat_enabled())
1550 : return;
1551 :
1552 : stats = __schedstats_from_dl_se(dl_se);
1553 : __update_stats_wait_start(rq_of_dl_rq(dl_rq), dl_task_of(dl_se), stats);
1554 : }
1555 :
1556 : static inline void
1557 : update_stats_wait_end_dl(struct dl_rq *dl_rq, struct sched_dl_entity *dl_se)
1558 : {
1559 : struct sched_statistics *stats;
1560 :
1561 : if (!schedstat_enabled())
1562 : return;
1563 :
1564 : stats = __schedstats_from_dl_se(dl_se);
1565 : __update_stats_wait_end(rq_of_dl_rq(dl_rq), dl_task_of(dl_se), stats);
1566 : }
1567 :
1568 : static inline void
1569 : update_stats_enqueue_sleeper_dl(struct dl_rq *dl_rq, struct sched_dl_entity *dl_se)
1570 : {
1571 : struct sched_statistics *stats;
1572 :
1573 : if (!schedstat_enabled())
1574 : return;
1575 :
1576 : stats = __schedstats_from_dl_se(dl_se);
1577 : __update_stats_enqueue_sleeper(rq_of_dl_rq(dl_rq), dl_task_of(dl_se), stats);
1578 : }
1579 :
1580 : static inline void
1581 : update_stats_enqueue_dl(struct dl_rq *dl_rq, struct sched_dl_entity *dl_se,
1582 : int flags)
1583 : {
1584 : if (!schedstat_enabled())
1585 : return;
1586 :
1587 : if (flags & ENQUEUE_WAKEUP)
1588 : update_stats_enqueue_sleeper_dl(dl_rq, dl_se);
1589 : }
1590 :
1591 : static inline void
1592 : update_stats_dequeue_dl(struct dl_rq *dl_rq, struct sched_dl_entity *dl_se,
1593 : int flags)
1594 : {
1595 0 : struct task_struct *p = dl_task_of(dl_se);
1596 :
1597 : if (!schedstat_enabled())
1598 : return;
1599 :
1600 : if ((flags & DEQUEUE_SLEEP)) {
1601 : unsigned int state;
1602 :
1603 : state = READ_ONCE(p->__state);
1604 : if (state & TASK_INTERRUPTIBLE)
1605 : __schedstat_set(p->stats.sleep_start,
1606 : rq_clock(rq_of_dl_rq(dl_rq)));
1607 :
1608 : if (state & TASK_UNINTERRUPTIBLE)
1609 : __schedstat_set(p->stats.block_start,
1610 : rq_clock(rq_of_dl_rq(dl_rq)));
1611 : }
1612 : }
1613 :
1614 0 : static void __enqueue_dl_entity(struct sched_dl_entity *dl_se)
1615 : {
1616 0 : struct dl_rq *dl_rq = dl_rq_of_se(dl_se);
1617 :
1618 0 : WARN_ON_ONCE(!RB_EMPTY_NODE(&dl_se->rb_node));
1619 :
1620 0 : rb_add_cached(&dl_se->rb_node, &dl_rq->root, __dl_less);
1621 :
1622 0 : inc_dl_tasks(dl_se, dl_rq);
1623 0 : }
1624 :
1625 0 : static void __dequeue_dl_entity(struct sched_dl_entity *dl_se)
1626 : {
1627 0 : struct dl_rq *dl_rq = dl_rq_of_se(dl_se);
1628 :
1629 0 : if (RB_EMPTY_NODE(&dl_se->rb_node))
1630 : return;
1631 :
1632 0 : rb_erase_cached(&dl_se->rb_node, &dl_rq->root);
1633 :
1634 0 : RB_CLEAR_NODE(&dl_se->rb_node);
1635 :
1636 0 : dec_dl_tasks(dl_se, dl_rq);
1637 : }
1638 :
1639 : static void
1640 0 : enqueue_dl_entity(struct sched_dl_entity *dl_se, int flags)
1641 : {
1642 0 : WARN_ON_ONCE(on_dl_rq(dl_se));
1643 :
1644 0 : update_stats_enqueue_dl(dl_rq_of_se(dl_se), dl_se, flags);
1645 :
1646 : /*
1647 : * If this is a wakeup or a new instance, the scheduling
1648 : * parameters of the task might need updating. Otherwise,
1649 : * we want a replenishment of its runtime.
1650 : */
1651 0 : if (flags & ENQUEUE_WAKEUP) {
1652 0 : task_contending(dl_se, flags);
1653 0 : update_dl_entity(dl_se);
1654 0 : } else if (flags & ENQUEUE_REPLENISH) {
1655 0 : replenish_dl_entity(dl_se);
1656 0 : } else if ((flags & ENQUEUE_RESTORE) &&
1657 0 : dl_time_before(dl_se->deadline,
1658 : rq_clock(rq_of_dl_rq(dl_rq_of_se(dl_se))))) {
1659 0 : setup_new_dl_entity(dl_se);
1660 : }
1661 :
1662 0 : __enqueue_dl_entity(dl_se);
1663 0 : }
1664 :
1665 : static void dequeue_dl_entity(struct sched_dl_entity *dl_se)
1666 : {
1667 0 : __dequeue_dl_entity(dl_se);
1668 : }
1669 :
1670 0 : static void enqueue_task_dl(struct rq *rq, struct task_struct *p, int flags)
1671 : {
1672 0 : if (is_dl_boosted(&p->dl)) {
1673 : /*
1674 : * Because of delays in the detection of the overrun of a
1675 : * thread's runtime, it might be the case that a thread
1676 : * goes to sleep in a rt mutex with negative runtime. As
1677 : * a consequence, the thread will be throttled.
1678 : *
1679 : * While waiting for the mutex, this thread can also be
1680 : * boosted via PI, resulting in a thread that is throttled
1681 : * and boosted at the same time.
1682 : *
1683 : * In this case, the boost overrides the throttle.
1684 : */
1685 0 : if (p->dl.dl_throttled) {
1686 : /*
1687 : * The replenish timer needs to be canceled. No
1688 : * problem if it fires concurrently: boosted threads
1689 : * are ignored in dl_task_timer().
1690 : */
1691 0 : hrtimer_try_to_cancel(&p->dl.dl_timer);
1692 0 : p->dl.dl_throttled = 0;
1693 : }
1694 0 : } else if (!dl_prio(p->normal_prio)) {
1695 : /*
1696 : * Special case in which we have a !SCHED_DEADLINE task that is going
1697 : * to be deboosted, but exceeds its runtime while doing so. No point in
1698 : * replenishing it, as it's going to return back to its original
1699 : * scheduling class after this. If it has been throttled, we need to
1700 : * clear the flag, otherwise the task may wake up as throttled after
1701 : * being boosted again with no means to replenish the runtime and clear
1702 : * the throttle.
1703 : */
1704 0 : p->dl.dl_throttled = 0;
1705 0 : if (!(flags & ENQUEUE_REPLENISH))
1706 0 : printk_deferred_once("sched: DL de-boosted task PID %d: REPLENISH flag missing\n",
1707 : task_pid_nr(p));
1708 :
1709 : return;
1710 : }
1711 :
1712 : /*
1713 : * Check if a constrained deadline task was activated
1714 : * after the deadline but before the next period.
1715 : * If that is the case, the task will be throttled and
1716 : * the replenishment timer will be set to the next period.
1717 : */
1718 0 : if (!p->dl.dl_throttled && !dl_is_implicit(&p->dl))
1719 0 : dl_check_constrained_dl(&p->dl);
1720 :
1721 0 : if (p->on_rq == TASK_ON_RQ_MIGRATING || flags & ENQUEUE_RESTORE) {
1722 0 : add_rq_bw(&p->dl, &rq->dl);
1723 0 : add_running_bw(&p->dl, &rq->dl);
1724 : }
1725 :
1726 : /*
1727 : * If p is throttled, we do not enqueue it. In fact, if it exhausted
1728 : * its budget it needs a replenishment and, since it now is on
1729 : * its rq, the bandwidth timer callback (which clearly has not
1730 : * run yet) will take care of this.
1731 : * However, the active utilization does not depend on the fact
1732 : * that the task is on the runqueue or not (but depends on the
1733 : * task's state - in GRUB parlance, "inactive" vs "active contending").
1734 : * In other words, even if a task is throttled its utilization must
1735 : * be counted in the active utilization; hence, we need to call
1736 : * add_running_bw().
1737 : */
1738 0 : if (p->dl.dl_throttled && !(flags & ENQUEUE_REPLENISH)) {
1739 0 : if (flags & ENQUEUE_WAKEUP)
1740 0 : task_contending(&p->dl, flags);
1741 :
1742 : return;
1743 : }
1744 :
1745 : check_schedstat_required();
1746 0 : update_stats_wait_start_dl(dl_rq_of_se(&p->dl), &p->dl);
1747 :
1748 0 : enqueue_dl_entity(&p->dl, flags);
1749 :
1750 0 : if (!task_current(rq, p) && p->nr_cpus_allowed > 1)
1751 : enqueue_pushable_dl_task(rq, p);
1752 : }
1753 :
1754 : static void __dequeue_task_dl(struct rq *rq, struct task_struct *p, int flags)
1755 : {
1756 0 : update_stats_dequeue_dl(&rq->dl, &p->dl, flags);
1757 0 : dequeue_dl_entity(&p->dl);
1758 0 : dequeue_pushable_dl_task(rq, p);
1759 : }
1760 :
1761 0 : static void dequeue_task_dl(struct rq *rq, struct task_struct *p, int flags)
1762 : {
1763 0 : update_curr_dl(rq);
1764 0 : __dequeue_task_dl(rq, p, flags);
1765 :
1766 0 : if (p->on_rq == TASK_ON_RQ_MIGRATING || flags & DEQUEUE_SAVE) {
1767 0 : sub_running_bw(&p->dl, &rq->dl);
1768 0 : sub_rq_bw(&p->dl, &rq->dl);
1769 : }
1770 :
1771 : /*
1772 : * This check allows to start the inactive timer (or to immediately
1773 : * decrease the active utilization, if needed) in two cases:
1774 : * when the task blocks and when it is terminating
1775 : * (p->state == TASK_DEAD). We can handle the two cases in the same
1776 : * way, because from GRUB's point of view the same thing is happening
1777 : * (the task moves from "active contending" to "active non contending"
1778 : * or "inactive")
1779 : */
1780 0 : if (flags & DEQUEUE_SLEEP)
1781 0 : task_non_contending(p);
1782 0 : }
1783 :
1784 : /*
1785 : * Yield task semantic for -deadline tasks is:
1786 : *
1787 : * get off from the CPU until our next instance, with
1788 : * a new runtime. This is of little use now, since we
1789 : * don't have a bandwidth reclaiming mechanism. Anyway,
1790 : * bandwidth reclaiming is planned for the future, and
1791 : * yield_task_dl will indicate that some spare budget
1792 : * is available for other task instances to use it.
1793 : */
1794 0 : static void yield_task_dl(struct rq *rq)
1795 : {
1796 : /*
1797 : * We make the task go to sleep until its current deadline by
1798 : * forcing its runtime to zero. This way, update_curr_dl() stops
1799 : * it and the bandwidth timer will wake it up and will give it
1800 : * new scheduling parameters (thanks to dl_yielded=1).
1801 : */
1802 0 : rq->curr->dl.dl_yielded = 1;
1803 :
1804 0 : update_rq_clock(rq);
1805 0 : update_curr_dl(rq);
1806 : /*
1807 : * Tell update_rq_clock() that we've just updated,
1808 : * so we don't do microscopic update in schedule()
1809 : * and double the fastpath cost.
1810 : */
1811 0 : rq_clock_skip_update(rq);
1812 0 : }
1813 :
1814 : #ifdef CONFIG_SMP
1815 :
1816 : static inline bool dl_task_is_earliest_deadline(struct task_struct *p,
1817 : struct rq *rq)
1818 : {
1819 : return (!rq->dl.dl_nr_running ||
1820 : dl_time_before(p->dl.deadline,
1821 : rq->dl.earliest_dl.curr));
1822 : }
1823 :
1824 : static int find_later_rq(struct task_struct *task);
1825 :
1826 : static int
1827 : select_task_rq_dl(struct task_struct *p, int cpu, int flags)
1828 : {
1829 : struct task_struct *curr;
1830 : bool select_rq;
1831 : struct rq *rq;
1832 :
1833 : if (!(flags & WF_TTWU))
1834 : goto out;
1835 :
1836 : rq = cpu_rq(cpu);
1837 :
1838 : rcu_read_lock();
1839 : curr = READ_ONCE(rq->curr); /* unlocked access */
1840 :
1841 : /*
1842 : * If we are dealing with a -deadline task, we must
1843 : * decide where to wake it up.
1844 : * If it has a later deadline and the current task
1845 : * on this rq can't move (provided the waking task
1846 : * can!) we prefer to send it somewhere else. On the
1847 : * other hand, if it has a shorter deadline, we
1848 : * try to make it stay here, it might be important.
1849 : */
1850 : select_rq = unlikely(dl_task(curr)) &&
1851 : (curr->nr_cpus_allowed < 2 ||
1852 : !dl_entity_preempt(&p->dl, &curr->dl)) &&
1853 : p->nr_cpus_allowed > 1;
1854 :
1855 : /*
1856 : * Take the capacity of the CPU into account to
1857 : * ensure it fits the requirement of the task.
1858 : */
1859 : if (sched_asym_cpucap_active())
1860 : select_rq |= !dl_task_fits_capacity(p, cpu);
1861 :
1862 : if (select_rq) {
1863 : int target = find_later_rq(p);
1864 :
1865 : if (target != -1 &&
1866 : dl_task_is_earliest_deadline(p, cpu_rq(target)))
1867 : cpu = target;
1868 : }
1869 : rcu_read_unlock();
1870 :
1871 : out:
1872 : return cpu;
1873 : }
1874 :
1875 : static void migrate_task_rq_dl(struct task_struct *p, int new_cpu __maybe_unused)
1876 : {
1877 : struct rq_flags rf;
1878 : struct rq *rq;
1879 :
1880 : if (READ_ONCE(p->__state) != TASK_WAKING)
1881 : return;
1882 :
1883 : rq = task_rq(p);
1884 : /*
1885 : * Since p->state == TASK_WAKING, set_task_cpu() has been called
1886 : * from try_to_wake_up(). Hence, p->pi_lock is locked, but
1887 : * rq->lock is not... So, lock it
1888 : */
1889 : rq_lock(rq, &rf);
1890 : if (p->dl.dl_non_contending) {
1891 : update_rq_clock(rq);
1892 : sub_running_bw(&p->dl, &rq->dl);
1893 : p->dl.dl_non_contending = 0;
1894 : /*
1895 : * If the timer handler is currently running and the
1896 : * timer cannot be canceled, inactive_task_timer()
1897 : * will see that dl_not_contending is not set, and
1898 : * will not touch the rq's active utilization,
1899 : * so we are still safe.
1900 : */
1901 : if (hrtimer_try_to_cancel(&p->dl.inactive_timer) == 1)
1902 : put_task_struct(p);
1903 : }
1904 : sub_rq_bw(&p->dl, &rq->dl);
1905 : rq_unlock(rq, &rf);
1906 : }
1907 :
1908 : static void check_preempt_equal_dl(struct rq *rq, struct task_struct *p)
1909 : {
1910 : /*
1911 : * Current can't be migrated, useless to reschedule,
1912 : * let's hope p can move out.
1913 : */
1914 : if (rq->curr->nr_cpus_allowed == 1 ||
1915 : !cpudl_find(&rq->rd->cpudl, rq->curr, NULL))
1916 : return;
1917 :
1918 : /*
1919 : * p is migratable, so let's not schedule it and
1920 : * see if it is pushed or pulled somewhere else.
1921 : */
1922 : if (p->nr_cpus_allowed != 1 &&
1923 : cpudl_find(&rq->rd->cpudl, p, NULL))
1924 : return;
1925 :
1926 : resched_curr(rq);
1927 : }
1928 :
1929 : static int balance_dl(struct rq *rq, struct task_struct *p, struct rq_flags *rf)
1930 : {
1931 : if (!on_dl_rq(&p->dl) && need_pull_dl_task(rq, p)) {
1932 : /*
1933 : * This is OK, because current is on_cpu, which avoids it being
1934 : * picked for load-balance and preemption/IRQs are still
1935 : * disabled avoiding further scheduler activity on it and we've
1936 : * not yet started the picking loop.
1937 : */
1938 : rq_unpin_lock(rq, rf);
1939 : pull_dl_task(rq);
1940 : rq_repin_lock(rq, rf);
1941 : }
1942 :
1943 : return sched_stop_runnable(rq) || sched_dl_runnable(rq);
1944 : }
1945 : #endif /* CONFIG_SMP */
1946 :
1947 : /*
1948 : * Only called when both the current and waking task are -deadline
1949 : * tasks.
1950 : */
1951 0 : static void check_preempt_curr_dl(struct rq *rq, struct task_struct *p,
1952 : int flags)
1953 : {
1954 0 : if (dl_entity_preempt(&p->dl, &rq->curr->dl)) {
1955 0 : resched_curr(rq);
1956 0 : return;
1957 : }
1958 :
1959 : #ifdef CONFIG_SMP
1960 : /*
1961 : * In the unlikely case current and p have the same deadline
1962 : * let us try to decide what's the best thing to do...
1963 : */
1964 : if ((p->dl.deadline == rq->curr->dl.deadline) &&
1965 : !test_tsk_need_resched(rq->curr))
1966 : check_preempt_equal_dl(rq, p);
1967 : #endif /* CONFIG_SMP */
1968 : }
1969 :
1970 : #ifdef CONFIG_SCHED_HRTICK
1971 : static void start_hrtick_dl(struct rq *rq, struct task_struct *p)
1972 : {
1973 : hrtick_start(rq, p->dl.runtime);
1974 : }
1975 : #else /* !CONFIG_SCHED_HRTICK */
1976 : static void start_hrtick_dl(struct rq *rq, struct task_struct *p)
1977 : {
1978 : }
1979 : #endif
1980 :
1981 0 : static void set_next_task_dl(struct rq *rq, struct task_struct *p, bool first)
1982 : {
1983 0 : struct sched_dl_entity *dl_se = &p->dl;
1984 0 : struct dl_rq *dl_rq = &rq->dl;
1985 :
1986 0 : p->se.exec_start = rq_clock_task(rq);
1987 0 : if (on_dl_rq(&p->dl))
1988 : update_stats_wait_end_dl(dl_rq, dl_se);
1989 :
1990 : /* You can't push away the running task */
1991 0 : dequeue_pushable_dl_task(rq, p);
1992 :
1993 0 : if (!first)
1994 : return;
1995 :
1996 0 : if (hrtick_enabled_dl(rq))
1997 : start_hrtick_dl(rq, p);
1998 :
1999 0 : if (rq->curr->sched_class != &dl_sched_class)
2000 0 : update_dl_rq_load_avg(rq_clock_pelt(rq), rq, 0);
2001 :
2002 : deadline_queue_push_tasks(rq);
2003 : }
2004 :
2005 : static struct sched_dl_entity *pick_next_dl_entity(struct dl_rq *dl_rq)
2006 : {
2007 0 : struct rb_node *left = rb_first_cached(&dl_rq->root);
2008 :
2009 0 : if (!left)
2010 : return NULL;
2011 :
2012 0 : return __node_2_dle(left);
2013 : }
2014 :
2015 0 : static struct task_struct *pick_task_dl(struct rq *rq)
2016 : {
2017 : struct sched_dl_entity *dl_se;
2018 0 : struct dl_rq *dl_rq = &rq->dl;
2019 : struct task_struct *p;
2020 :
2021 0 : if (!sched_dl_runnable(rq))
2022 : return NULL;
2023 :
2024 0 : dl_se = pick_next_dl_entity(dl_rq);
2025 0 : WARN_ON_ONCE(!dl_se);
2026 0 : p = dl_task_of(dl_se);
2027 :
2028 0 : return p;
2029 : }
2030 :
2031 0 : static struct task_struct *pick_next_task_dl(struct rq *rq)
2032 : {
2033 : struct task_struct *p;
2034 :
2035 0 : p = pick_task_dl(rq);
2036 0 : if (p)
2037 0 : set_next_task_dl(rq, p, true);
2038 :
2039 0 : return p;
2040 : }
2041 :
2042 0 : static void put_prev_task_dl(struct rq *rq, struct task_struct *p)
2043 : {
2044 0 : struct sched_dl_entity *dl_se = &p->dl;
2045 0 : struct dl_rq *dl_rq = &rq->dl;
2046 :
2047 0 : if (on_dl_rq(&p->dl))
2048 : update_stats_wait_start_dl(dl_rq, dl_se);
2049 :
2050 0 : update_curr_dl(rq);
2051 :
2052 0 : update_dl_rq_load_avg(rq_clock_pelt(rq), rq, 1);
2053 0 : if (on_dl_rq(&p->dl) && p->nr_cpus_allowed > 1)
2054 : enqueue_pushable_dl_task(rq, p);
2055 0 : }
2056 :
2057 : /*
2058 : * scheduler tick hitting a task of our scheduling class.
2059 : *
2060 : * NOTE: This function can be called remotely by the tick offload that
2061 : * goes along full dynticks. Therefore no local assumption can be made
2062 : * and everything must be accessed through the @rq and @curr passed in
2063 : * parameters.
2064 : */
2065 0 : static void task_tick_dl(struct rq *rq, struct task_struct *p, int queued)
2066 : {
2067 0 : update_curr_dl(rq);
2068 :
2069 0 : update_dl_rq_load_avg(rq_clock_pelt(rq), rq, 1);
2070 : /*
2071 : * Even when we have runtime, update_curr_dl() might have resulted in us
2072 : * not being the leftmost task anymore. In that case NEED_RESCHED will
2073 : * be set and schedule() will start a new hrtick for the next task.
2074 : */
2075 0 : if (hrtick_enabled_dl(rq) && queued && p->dl.runtime > 0 &&
2076 : is_leftmost(p, &rq->dl))
2077 : start_hrtick_dl(rq, p);
2078 0 : }
2079 :
2080 0 : static void task_fork_dl(struct task_struct *p)
2081 : {
2082 : /*
2083 : * SCHED_DEADLINE tasks cannot fork and this is achieved through
2084 : * sched_fork()
2085 : */
2086 0 : }
2087 :
2088 : #ifdef CONFIG_SMP
2089 :
2090 : /* Only try algorithms three times */
2091 : #define DL_MAX_TRIES 3
2092 :
2093 : static int pick_dl_task(struct rq *rq, struct task_struct *p, int cpu)
2094 : {
2095 : if (!task_on_cpu(rq, p) &&
2096 : cpumask_test_cpu(cpu, &p->cpus_mask))
2097 : return 1;
2098 : return 0;
2099 : }
2100 :
2101 : /*
2102 : * Return the earliest pushable rq's task, which is suitable to be executed
2103 : * on the CPU, NULL otherwise:
2104 : */
2105 : static struct task_struct *pick_earliest_pushable_dl_task(struct rq *rq, int cpu)
2106 : {
2107 : struct task_struct *p = NULL;
2108 : struct rb_node *next_node;
2109 :
2110 : if (!has_pushable_dl_tasks(rq))
2111 : return NULL;
2112 :
2113 : next_node = rb_first_cached(&rq->dl.pushable_dl_tasks_root);
2114 :
2115 : next_node:
2116 : if (next_node) {
2117 : p = __node_2_pdl(next_node);
2118 :
2119 : if (pick_dl_task(rq, p, cpu))
2120 : return p;
2121 :
2122 : next_node = rb_next(next_node);
2123 : goto next_node;
2124 : }
2125 :
2126 : return NULL;
2127 : }
2128 :
2129 : static DEFINE_PER_CPU(cpumask_var_t, local_cpu_mask_dl);
2130 :
2131 : static int find_later_rq(struct task_struct *task)
2132 : {
2133 : struct sched_domain *sd;
2134 : struct cpumask *later_mask = this_cpu_cpumask_var_ptr(local_cpu_mask_dl);
2135 : int this_cpu = smp_processor_id();
2136 : int cpu = task_cpu(task);
2137 :
2138 : /* Make sure the mask is initialized first */
2139 : if (unlikely(!later_mask))
2140 : return -1;
2141 :
2142 : if (task->nr_cpus_allowed == 1)
2143 : return -1;
2144 :
2145 : /*
2146 : * We have to consider system topology and task affinity
2147 : * first, then we can look for a suitable CPU.
2148 : */
2149 : if (!cpudl_find(&task_rq(task)->rd->cpudl, task, later_mask))
2150 : return -1;
2151 :
2152 : /*
2153 : * If we are here, some targets have been found, including
2154 : * the most suitable which is, among the runqueues where the
2155 : * current tasks have later deadlines than the task's one, the
2156 : * rq with the latest possible one.
2157 : *
2158 : * Now we check how well this matches with task's
2159 : * affinity and system topology.
2160 : *
2161 : * The last CPU where the task run is our first
2162 : * guess, since it is most likely cache-hot there.
2163 : */
2164 : if (cpumask_test_cpu(cpu, later_mask))
2165 : return cpu;
2166 : /*
2167 : * Check if this_cpu is to be skipped (i.e., it is
2168 : * not in the mask) or not.
2169 : */
2170 : if (!cpumask_test_cpu(this_cpu, later_mask))
2171 : this_cpu = -1;
2172 :
2173 : rcu_read_lock();
2174 : for_each_domain(cpu, sd) {
2175 : if (sd->flags & SD_WAKE_AFFINE) {
2176 : int best_cpu;
2177 :
2178 : /*
2179 : * If possible, preempting this_cpu is
2180 : * cheaper than migrating.
2181 : */
2182 : if (this_cpu != -1 &&
2183 : cpumask_test_cpu(this_cpu, sched_domain_span(sd))) {
2184 : rcu_read_unlock();
2185 : return this_cpu;
2186 : }
2187 :
2188 : best_cpu = cpumask_any_and_distribute(later_mask,
2189 : sched_domain_span(sd));
2190 : /*
2191 : * Last chance: if a CPU being in both later_mask
2192 : * and current sd span is valid, that becomes our
2193 : * choice. Of course, the latest possible CPU is
2194 : * already under consideration through later_mask.
2195 : */
2196 : if (best_cpu < nr_cpu_ids) {
2197 : rcu_read_unlock();
2198 : return best_cpu;
2199 : }
2200 : }
2201 : }
2202 : rcu_read_unlock();
2203 :
2204 : /*
2205 : * At this point, all our guesses failed, we just return
2206 : * 'something', and let the caller sort the things out.
2207 : */
2208 : if (this_cpu != -1)
2209 : return this_cpu;
2210 :
2211 : cpu = cpumask_any_distribute(later_mask);
2212 : if (cpu < nr_cpu_ids)
2213 : return cpu;
2214 :
2215 : return -1;
2216 : }
2217 :
2218 : /* Locks the rq it finds */
2219 : static struct rq *find_lock_later_rq(struct task_struct *task, struct rq *rq)
2220 : {
2221 : struct rq *later_rq = NULL;
2222 : int tries;
2223 : int cpu;
2224 :
2225 : for (tries = 0; tries < DL_MAX_TRIES; tries++) {
2226 : cpu = find_later_rq(task);
2227 :
2228 : if ((cpu == -1) || (cpu == rq->cpu))
2229 : break;
2230 :
2231 : later_rq = cpu_rq(cpu);
2232 :
2233 : if (!dl_task_is_earliest_deadline(task, later_rq)) {
2234 : /*
2235 : * Target rq has tasks of equal or earlier deadline,
2236 : * retrying does not release any lock and is unlikely
2237 : * to yield a different result.
2238 : */
2239 : later_rq = NULL;
2240 : break;
2241 : }
2242 :
2243 : /* Retry if something changed. */
2244 : if (double_lock_balance(rq, later_rq)) {
2245 : if (unlikely(task_rq(task) != rq ||
2246 : !cpumask_test_cpu(later_rq->cpu, &task->cpus_mask) ||
2247 : task_on_cpu(rq, task) ||
2248 : !dl_task(task) ||
2249 : !task_on_rq_queued(task))) {
2250 : double_unlock_balance(rq, later_rq);
2251 : later_rq = NULL;
2252 : break;
2253 : }
2254 : }
2255 :
2256 : /*
2257 : * If the rq we found has no -deadline task, or
2258 : * its earliest one has a later deadline than our
2259 : * task, the rq is a good one.
2260 : */
2261 : if (dl_task_is_earliest_deadline(task, later_rq))
2262 : break;
2263 :
2264 : /* Otherwise we try again. */
2265 : double_unlock_balance(rq, later_rq);
2266 : later_rq = NULL;
2267 : }
2268 :
2269 : return later_rq;
2270 : }
2271 :
2272 : static struct task_struct *pick_next_pushable_dl_task(struct rq *rq)
2273 : {
2274 : struct task_struct *p;
2275 :
2276 : if (!has_pushable_dl_tasks(rq))
2277 : return NULL;
2278 :
2279 : p = __node_2_pdl(rb_first_cached(&rq->dl.pushable_dl_tasks_root));
2280 :
2281 : WARN_ON_ONCE(rq->cpu != task_cpu(p));
2282 : WARN_ON_ONCE(task_current(rq, p));
2283 : WARN_ON_ONCE(p->nr_cpus_allowed <= 1);
2284 :
2285 : WARN_ON_ONCE(!task_on_rq_queued(p));
2286 : WARN_ON_ONCE(!dl_task(p));
2287 :
2288 : return p;
2289 : }
2290 :
2291 : /*
2292 : * See if the non running -deadline tasks on this rq
2293 : * can be sent to some other CPU where they can preempt
2294 : * and start executing.
2295 : */
2296 : static int push_dl_task(struct rq *rq)
2297 : {
2298 : struct task_struct *next_task;
2299 : struct rq *later_rq;
2300 : int ret = 0;
2301 :
2302 : if (!rq->dl.overloaded)
2303 : return 0;
2304 :
2305 : next_task = pick_next_pushable_dl_task(rq);
2306 : if (!next_task)
2307 : return 0;
2308 :
2309 : retry:
2310 : /*
2311 : * If next_task preempts rq->curr, and rq->curr
2312 : * can move away, it makes sense to just reschedule
2313 : * without going further in pushing next_task.
2314 : */
2315 : if (dl_task(rq->curr) &&
2316 : dl_time_before(next_task->dl.deadline, rq->curr->dl.deadline) &&
2317 : rq->curr->nr_cpus_allowed > 1) {
2318 : resched_curr(rq);
2319 : return 0;
2320 : }
2321 :
2322 : if (is_migration_disabled(next_task))
2323 : return 0;
2324 :
2325 : if (WARN_ON(next_task == rq->curr))
2326 : return 0;
2327 :
2328 : /* We might release rq lock */
2329 : get_task_struct(next_task);
2330 :
2331 : /* Will lock the rq it'll find */
2332 : later_rq = find_lock_later_rq(next_task, rq);
2333 : if (!later_rq) {
2334 : struct task_struct *task;
2335 :
2336 : /*
2337 : * We must check all this again, since
2338 : * find_lock_later_rq releases rq->lock and it is
2339 : * then possible that next_task has migrated.
2340 : */
2341 : task = pick_next_pushable_dl_task(rq);
2342 : if (task == next_task) {
2343 : /*
2344 : * The task is still there. We don't try
2345 : * again, some other CPU will pull it when ready.
2346 : */
2347 : goto out;
2348 : }
2349 :
2350 : if (!task)
2351 : /* No more tasks */
2352 : goto out;
2353 :
2354 : put_task_struct(next_task);
2355 : next_task = task;
2356 : goto retry;
2357 : }
2358 :
2359 : deactivate_task(rq, next_task, 0);
2360 : set_task_cpu(next_task, later_rq->cpu);
2361 : activate_task(later_rq, next_task, 0);
2362 : ret = 1;
2363 :
2364 : resched_curr(later_rq);
2365 :
2366 : double_unlock_balance(rq, later_rq);
2367 :
2368 : out:
2369 : put_task_struct(next_task);
2370 :
2371 : return ret;
2372 : }
2373 :
2374 : static void push_dl_tasks(struct rq *rq)
2375 : {
2376 : /* push_dl_task() will return true if it moved a -deadline task */
2377 : while (push_dl_task(rq))
2378 : ;
2379 : }
2380 :
2381 : static void pull_dl_task(struct rq *this_rq)
2382 : {
2383 : int this_cpu = this_rq->cpu, cpu;
2384 : struct task_struct *p, *push_task;
2385 : bool resched = false;
2386 : struct rq *src_rq;
2387 : u64 dmin = LONG_MAX;
2388 :
2389 : if (likely(!dl_overloaded(this_rq)))
2390 : return;
2391 :
2392 : /*
2393 : * Match the barrier from dl_set_overloaded; this guarantees that if we
2394 : * see overloaded we must also see the dlo_mask bit.
2395 : */
2396 : smp_rmb();
2397 :
2398 : for_each_cpu(cpu, this_rq->rd->dlo_mask) {
2399 : if (this_cpu == cpu)
2400 : continue;
2401 :
2402 : src_rq = cpu_rq(cpu);
2403 :
2404 : /*
2405 : * It looks racy, abd it is! However, as in sched_rt.c,
2406 : * we are fine with this.
2407 : */
2408 : if (this_rq->dl.dl_nr_running &&
2409 : dl_time_before(this_rq->dl.earliest_dl.curr,
2410 : src_rq->dl.earliest_dl.next))
2411 : continue;
2412 :
2413 : /* Might drop this_rq->lock */
2414 : push_task = NULL;
2415 : double_lock_balance(this_rq, src_rq);
2416 :
2417 : /*
2418 : * If there are no more pullable tasks on the
2419 : * rq, we're done with it.
2420 : */
2421 : if (src_rq->dl.dl_nr_running <= 1)
2422 : goto skip;
2423 :
2424 : p = pick_earliest_pushable_dl_task(src_rq, this_cpu);
2425 :
2426 : /*
2427 : * We found a task to be pulled if:
2428 : * - it preempts our current (if there's one),
2429 : * - it will preempt the last one we pulled (if any).
2430 : */
2431 : if (p && dl_time_before(p->dl.deadline, dmin) &&
2432 : dl_task_is_earliest_deadline(p, this_rq)) {
2433 : WARN_ON(p == src_rq->curr);
2434 : WARN_ON(!task_on_rq_queued(p));
2435 :
2436 : /*
2437 : * Then we pull iff p has actually an earlier
2438 : * deadline than the current task of its runqueue.
2439 : */
2440 : if (dl_time_before(p->dl.deadline,
2441 : src_rq->curr->dl.deadline))
2442 : goto skip;
2443 :
2444 : if (is_migration_disabled(p)) {
2445 : push_task = get_push_task(src_rq);
2446 : } else {
2447 : deactivate_task(src_rq, p, 0);
2448 : set_task_cpu(p, this_cpu);
2449 : activate_task(this_rq, p, 0);
2450 : dmin = p->dl.deadline;
2451 : resched = true;
2452 : }
2453 :
2454 : /* Is there any other task even earlier? */
2455 : }
2456 : skip:
2457 : double_unlock_balance(this_rq, src_rq);
2458 :
2459 : if (push_task) {
2460 : raw_spin_rq_unlock(this_rq);
2461 : stop_one_cpu_nowait(src_rq->cpu, push_cpu_stop,
2462 : push_task, &src_rq->push_work);
2463 : raw_spin_rq_lock(this_rq);
2464 : }
2465 : }
2466 :
2467 : if (resched)
2468 : resched_curr(this_rq);
2469 : }
2470 :
2471 : /*
2472 : * Since the task is not running and a reschedule is not going to happen
2473 : * anytime soon on its runqueue, we try pushing it away now.
2474 : */
2475 : static void task_woken_dl(struct rq *rq, struct task_struct *p)
2476 : {
2477 : if (!task_on_cpu(rq, p) &&
2478 : !test_tsk_need_resched(rq->curr) &&
2479 : p->nr_cpus_allowed > 1 &&
2480 : dl_task(rq->curr) &&
2481 : (rq->curr->nr_cpus_allowed < 2 ||
2482 : !dl_entity_preempt(&p->dl, &rq->curr->dl))) {
2483 : push_dl_tasks(rq);
2484 : }
2485 : }
2486 :
2487 : static void set_cpus_allowed_dl(struct task_struct *p,
2488 : struct affinity_context *ctx)
2489 : {
2490 : struct root_domain *src_rd;
2491 : struct rq *rq;
2492 :
2493 : WARN_ON_ONCE(!dl_task(p));
2494 :
2495 : rq = task_rq(p);
2496 : src_rd = rq->rd;
2497 : /*
2498 : * Migrating a SCHED_DEADLINE task between exclusive
2499 : * cpusets (different root_domains) entails a bandwidth
2500 : * update. We already made space for us in the destination
2501 : * domain (see cpuset_can_attach()).
2502 : */
2503 : if (!cpumask_intersects(src_rd->span, ctx->new_mask)) {
2504 : struct dl_bw *src_dl_b;
2505 :
2506 : src_dl_b = dl_bw_of(cpu_of(rq));
2507 : /*
2508 : * We now free resources of the root_domain we are migrating
2509 : * off. In the worst case, sched_setattr() may temporary fail
2510 : * until we complete the update.
2511 : */
2512 : raw_spin_lock(&src_dl_b->lock);
2513 : __dl_sub(src_dl_b, p->dl.dl_bw, dl_bw_cpus(task_cpu(p)));
2514 : raw_spin_unlock(&src_dl_b->lock);
2515 : }
2516 :
2517 : set_cpus_allowed_common(p, ctx);
2518 : }
2519 :
2520 : /* Assumes rq->lock is held */
2521 : static void rq_online_dl(struct rq *rq)
2522 : {
2523 : if (rq->dl.overloaded)
2524 : dl_set_overload(rq);
2525 :
2526 : cpudl_set_freecpu(&rq->rd->cpudl, rq->cpu);
2527 : if (rq->dl.dl_nr_running > 0)
2528 : cpudl_set(&rq->rd->cpudl, rq->cpu, rq->dl.earliest_dl.curr);
2529 : }
2530 :
2531 : /* Assumes rq->lock is held */
2532 : static void rq_offline_dl(struct rq *rq)
2533 : {
2534 : if (rq->dl.overloaded)
2535 : dl_clear_overload(rq);
2536 :
2537 : cpudl_clear(&rq->rd->cpudl, rq->cpu);
2538 : cpudl_clear_freecpu(&rq->rd->cpudl, rq->cpu);
2539 : }
2540 :
2541 : void __init init_sched_dl_class(void)
2542 : {
2543 : unsigned int i;
2544 :
2545 : for_each_possible_cpu(i)
2546 : zalloc_cpumask_var_node(&per_cpu(local_cpu_mask_dl, i),
2547 : GFP_KERNEL, cpu_to_node(i));
2548 : }
2549 :
2550 : void dl_add_task_root_domain(struct task_struct *p)
2551 : {
2552 : struct rq_flags rf;
2553 : struct rq *rq;
2554 : struct dl_bw *dl_b;
2555 :
2556 : raw_spin_lock_irqsave(&p->pi_lock, rf.flags);
2557 : if (!dl_task(p)) {
2558 : raw_spin_unlock_irqrestore(&p->pi_lock, rf.flags);
2559 : return;
2560 : }
2561 :
2562 : rq = __task_rq_lock(p, &rf);
2563 :
2564 : dl_b = &rq->rd->dl_bw;
2565 : raw_spin_lock(&dl_b->lock);
2566 :
2567 : __dl_add(dl_b, p->dl.dl_bw, cpumask_weight(rq->rd->span));
2568 :
2569 : raw_spin_unlock(&dl_b->lock);
2570 :
2571 : task_rq_unlock(rq, p, &rf);
2572 : }
2573 :
2574 : void dl_clear_root_domain(struct root_domain *rd)
2575 : {
2576 : unsigned long flags;
2577 :
2578 : raw_spin_lock_irqsave(&rd->dl_bw.lock, flags);
2579 : rd->dl_bw.total_bw = 0;
2580 : raw_spin_unlock_irqrestore(&rd->dl_bw.lock, flags);
2581 : }
2582 :
2583 : #endif /* CONFIG_SMP */
2584 :
2585 0 : static void switched_from_dl(struct rq *rq, struct task_struct *p)
2586 : {
2587 : /*
2588 : * task_non_contending() can start the "inactive timer" (if the 0-lag
2589 : * time is in the future). If the task switches back to dl before
2590 : * the "inactive timer" fires, it can continue to consume its current
2591 : * runtime using its current deadline. If it stays outside of
2592 : * SCHED_DEADLINE until the 0-lag time passes, inactive_task_timer()
2593 : * will reset the task parameters.
2594 : */
2595 0 : if (task_on_rq_queued(p) && p->dl.dl_runtime)
2596 0 : task_non_contending(p);
2597 :
2598 0 : if (!task_on_rq_queued(p)) {
2599 : /*
2600 : * Inactive timer is armed. However, p is leaving DEADLINE and
2601 : * might migrate away from this rq while continuing to run on
2602 : * some other class. We need to remove its contribution from
2603 : * this rq running_bw now, or sub_rq_bw (below) will complain.
2604 : */
2605 0 : if (p->dl.dl_non_contending)
2606 0 : sub_running_bw(&p->dl, &rq->dl);
2607 0 : sub_rq_bw(&p->dl, &rq->dl);
2608 : }
2609 :
2610 : /*
2611 : * We cannot use inactive_task_timer() to invoke sub_running_bw()
2612 : * at the 0-lag time, because the task could have been migrated
2613 : * while SCHED_OTHER in the meanwhile.
2614 : */
2615 0 : if (p->dl.dl_non_contending)
2616 0 : p->dl.dl_non_contending = 0;
2617 :
2618 : /*
2619 : * Since this might be the only -deadline task on the rq,
2620 : * this is the right place to try to pull some other one
2621 : * from an overloaded CPU, if any.
2622 : */
2623 0 : if (!task_on_rq_queued(p) || rq->dl.dl_nr_running)
2624 : return;
2625 :
2626 : deadline_queue_pull_task(rq);
2627 : }
2628 :
2629 : /*
2630 : * When switching to -deadline, we may overload the rq, then
2631 : * we try to push someone off, if possible.
2632 : */
2633 0 : static void switched_to_dl(struct rq *rq, struct task_struct *p)
2634 : {
2635 0 : if (hrtimer_try_to_cancel(&p->dl.inactive_timer) == 1)
2636 0 : put_task_struct(p);
2637 :
2638 : /* If p is not queued we will update its parameters at next wakeup. */
2639 0 : if (!task_on_rq_queued(p)) {
2640 0 : add_rq_bw(&p->dl, &rq->dl);
2641 :
2642 : return;
2643 : }
2644 :
2645 0 : if (rq->curr != p) {
2646 : #ifdef CONFIG_SMP
2647 : if (p->nr_cpus_allowed > 1 && rq->dl.overloaded)
2648 : deadline_queue_push_tasks(rq);
2649 : #endif
2650 0 : if (dl_task(rq->curr))
2651 : check_preempt_curr_dl(rq, p, 0);
2652 : else
2653 0 : resched_curr(rq);
2654 : } else {
2655 0 : update_dl_rq_load_avg(rq_clock_pelt(rq), rq, 0);
2656 : }
2657 : }
2658 :
2659 : /*
2660 : * If the scheduling parameters of a -deadline task changed,
2661 : * a push or pull operation might be needed.
2662 : */
2663 0 : static void prio_changed_dl(struct rq *rq, struct task_struct *p,
2664 : int oldprio)
2665 : {
2666 0 : if (!task_on_rq_queued(p))
2667 : return;
2668 :
2669 : #ifdef CONFIG_SMP
2670 : /*
2671 : * This might be too much, but unfortunately
2672 : * we don't have the old deadline value, and
2673 : * we can't argue if the task is increasing
2674 : * or lowering its prio, so...
2675 : */
2676 : if (!rq->dl.overloaded)
2677 : deadline_queue_pull_task(rq);
2678 :
2679 : if (task_current(rq, p)) {
2680 : /*
2681 : * If we now have a earlier deadline task than p,
2682 : * then reschedule, provided p is still on this
2683 : * runqueue.
2684 : */
2685 : if (dl_time_before(rq->dl.earliest_dl.curr, p->dl.deadline))
2686 : resched_curr(rq);
2687 : } else {
2688 : /*
2689 : * Current may not be deadline in case p was throttled but we
2690 : * have just replenished it (e.g. rt_mutex_setprio()).
2691 : *
2692 : * Otherwise, if p was given an earlier deadline, reschedule.
2693 : */
2694 : if (!dl_task(rq->curr) ||
2695 : dl_time_before(p->dl.deadline, rq->curr->dl.deadline))
2696 : resched_curr(rq);
2697 : }
2698 : #else
2699 : /*
2700 : * We don't know if p has a earlier or later deadline, so let's blindly
2701 : * set a (maybe not needed) rescheduling point.
2702 : */
2703 0 : resched_curr(rq);
2704 : #endif
2705 : }
2706 :
2707 : DEFINE_SCHED_CLASS(dl) = {
2708 :
2709 : .enqueue_task = enqueue_task_dl,
2710 : .dequeue_task = dequeue_task_dl,
2711 : .yield_task = yield_task_dl,
2712 :
2713 : .check_preempt_curr = check_preempt_curr_dl,
2714 :
2715 : .pick_next_task = pick_next_task_dl,
2716 : .put_prev_task = put_prev_task_dl,
2717 : .set_next_task = set_next_task_dl,
2718 :
2719 : #ifdef CONFIG_SMP
2720 : .balance = balance_dl,
2721 : .pick_task = pick_task_dl,
2722 : .select_task_rq = select_task_rq_dl,
2723 : .migrate_task_rq = migrate_task_rq_dl,
2724 : .set_cpus_allowed = set_cpus_allowed_dl,
2725 : .rq_online = rq_online_dl,
2726 : .rq_offline = rq_offline_dl,
2727 : .task_woken = task_woken_dl,
2728 : .find_lock_rq = find_lock_later_rq,
2729 : #endif
2730 :
2731 : .task_tick = task_tick_dl,
2732 : .task_fork = task_fork_dl,
2733 :
2734 : .prio_changed = prio_changed_dl,
2735 : .switched_from = switched_from_dl,
2736 : .switched_to = switched_to_dl,
2737 :
2738 : .update_curr = update_curr_dl,
2739 : };
2740 :
2741 : /* Used for dl_bw check and update, used under sched_rt_handler()::mutex */
2742 : static u64 dl_generation;
2743 :
2744 0 : int sched_dl_global_validate(void)
2745 : {
2746 0 : u64 runtime = global_rt_runtime();
2747 0 : u64 period = global_rt_period();
2748 0 : u64 new_bw = to_ratio(period, runtime);
2749 0 : u64 gen = ++dl_generation;
2750 : struct dl_bw *dl_b;
2751 0 : int cpu, cpus, ret = 0;
2752 : unsigned long flags;
2753 :
2754 : /*
2755 : * Here we want to check the bandwidth not being set to some
2756 : * value smaller than the currently allocated bandwidth in
2757 : * any of the root_domains.
2758 : */
2759 0 : for_each_possible_cpu(cpu) {
2760 : rcu_read_lock_sched();
2761 :
2762 0 : if (dl_bw_visited(cpu, gen))
2763 : goto next;
2764 :
2765 0 : dl_b = dl_bw_of(cpu);
2766 0 : cpus = dl_bw_cpus(cpu);
2767 :
2768 0 : raw_spin_lock_irqsave(&dl_b->lock, flags);
2769 0 : if (new_bw * cpus < dl_b->total_bw)
2770 0 : ret = -EBUSY;
2771 0 : raw_spin_unlock_irqrestore(&dl_b->lock, flags);
2772 :
2773 : next:
2774 : rcu_read_unlock_sched();
2775 :
2776 0 : if (ret)
2777 : break;
2778 : }
2779 :
2780 0 : return ret;
2781 : }
2782 :
2783 1 : static void init_dl_rq_bw_ratio(struct dl_rq *dl_rq)
2784 : {
2785 1 : if (global_rt_runtime() == RUNTIME_INF) {
2786 0 : dl_rq->bw_ratio = 1 << RATIO_SHIFT;
2787 0 : dl_rq->extra_bw = 1 << BW_SHIFT;
2788 : } else {
2789 2 : dl_rq->bw_ratio = to_ratio(global_rt_runtime(),
2790 1 : global_rt_period()) >> (BW_SHIFT - RATIO_SHIFT);
2791 1 : dl_rq->extra_bw = to_ratio(global_rt_period(),
2792 : global_rt_runtime());
2793 : }
2794 1 : }
2795 :
2796 0 : void sched_dl_do_global(void)
2797 : {
2798 0 : u64 new_bw = -1;
2799 0 : u64 gen = ++dl_generation;
2800 : struct dl_bw *dl_b;
2801 : int cpu;
2802 : unsigned long flags;
2803 :
2804 0 : if (global_rt_runtime() != RUNTIME_INF)
2805 0 : new_bw = to_ratio(global_rt_period(), global_rt_runtime());
2806 :
2807 0 : for_each_possible_cpu(cpu) {
2808 : rcu_read_lock_sched();
2809 :
2810 0 : if (dl_bw_visited(cpu, gen)) {
2811 : rcu_read_unlock_sched();
2812 : continue;
2813 : }
2814 :
2815 0 : dl_b = dl_bw_of(cpu);
2816 :
2817 0 : raw_spin_lock_irqsave(&dl_b->lock, flags);
2818 0 : dl_b->bw = new_bw;
2819 0 : raw_spin_unlock_irqrestore(&dl_b->lock, flags);
2820 :
2821 : rcu_read_unlock_sched();
2822 0 : init_dl_rq_bw_ratio(&cpu_rq(cpu)->dl);
2823 : }
2824 0 : }
2825 :
2826 : /*
2827 : * We must be sure that accepting a new task (or allowing changing the
2828 : * parameters of an existing one) is consistent with the bandwidth
2829 : * constraints. If yes, this function also accordingly updates the currently
2830 : * allocated bandwidth to reflect the new situation.
2831 : *
2832 : * This function is called while holding p's rq->lock.
2833 : */
2834 0 : int sched_dl_overflow(struct task_struct *p, int policy,
2835 : const struct sched_attr *attr)
2836 : {
2837 0 : u64 period = attr->sched_period ?: attr->sched_deadline;
2838 0 : u64 runtime = attr->sched_runtime;
2839 0 : u64 new_bw = dl_policy(policy) ? to_ratio(period, runtime) : 0;
2840 0 : int cpus, err = -1, cpu = task_cpu(p);
2841 0 : struct dl_bw *dl_b = dl_bw_of(cpu);
2842 : unsigned long cap;
2843 :
2844 0 : if (attr->sched_flags & SCHED_FLAG_SUGOV)
2845 : return 0;
2846 :
2847 : /* !deadline task may carry old deadline bandwidth */
2848 0 : if (new_bw == p->dl.dl_bw && task_has_dl_policy(p))
2849 : return 0;
2850 :
2851 : /*
2852 : * Either if a task, enters, leave, or stays -deadline but changes
2853 : * its parameters, we may need to update accordingly the total
2854 : * allocated bandwidth of the container.
2855 : */
2856 0 : raw_spin_lock(&dl_b->lock);
2857 0 : cpus = dl_bw_cpus(cpu);
2858 0 : cap = dl_bw_capacity(cpu);
2859 :
2860 0 : if (dl_policy(policy) && !task_has_dl_policy(p) &&
2861 0 : !__dl_overflow(dl_b, cap, 0, new_bw)) {
2862 0 : if (hrtimer_active(&p->dl.inactive_timer))
2863 0 : __dl_sub(dl_b, p->dl.dl_bw, cpus);
2864 0 : __dl_add(dl_b, new_bw, cpus);
2865 0 : err = 0;
2866 0 : } else if (dl_policy(policy) && task_has_dl_policy(p) &&
2867 0 : !__dl_overflow(dl_b, cap, p->dl.dl_bw, new_bw)) {
2868 : /*
2869 : * XXX this is slightly incorrect: when the task
2870 : * utilization decreases, we should delay the total
2871 : * utilization change until the task's 0-lag point.
2872 : * But this would require to set the task's "inactive
2873 : * timer" when the task is not inactive.
2874 : */
2875 0 : __dl_sub(dl_b, p->dl.dl_bw, cpus);
2876 0 : __dl_add(dl_b, new_bw, cpus);
2877 0 : dl_change_utilization(p, new_bw);
2878 0 : err = 0;
2879 0 : } else if (!dl_policy(policy) && task_has_dl_policy(p)) {
2880 : /*
2881 : * Do not decrease the total deadline utilization here,
2882 : * switched_from_dl() will take care to do it at the correct
2883 : * (0-lag) time.
2884 : */
2885 0 : err = 0;
2886 : }
2887 0 : raw_spin_unlock(&dl_b->lock);
2888 :
2889 0 : return err;
2890 : }
2891 :
2892 : /*
2893 : * This function initializes the sched_dl_entity of a newly becoming
2894 : * SCHED_DEADLINE task.
2895 : *
2896 : * Only the static values are considered here, the actual runtime and the
2897 : * absolute deadline will be properly calculated when the task is enqueued
2898 : * for the first time with its new policy.
2899 : */
2900 0 : void __setparam_dl(struct task_struct *p, const struct sched_attr *attr)
2901 : {
2902 0 : struct sched_dl_entity *dl_se = &p->dl;
2903 :
2904 0 : dl_se->dl_runtime = attr->sched_runtime;
2905 0 : dl_se->dl_deadline = attr->sched_deadline;
2906 0 : dl_se->dl_period = attr->sched_period ?: dl_se->dl_deadline;
2907 0 : dl_se->flags = attr->sched_flags & SCHED_DL_FLAGS;
2908 0 : dl_se->dl_bw = to_ratio(dl_se->dl_period, dl_se->dl_runtime);
2909 0 : dl_se->dl_density = to_ratio(dl_se->dl_deadline, dl_se->dl_runtime);
2910 0 : }
2911 :
2912 0 : void __getparam_dl(struct task_struct *p, struct sched_attr *attr)
2913 : {
2914 0 : struct sched_dl_entity *dl_se = &p->dl;
2915 :
2916 0 : attr->sched_priority = p->rt_priority;
2917 0 : attr->sched_runtime = dl_se->dl_runtime;
2918 0 : attr->sched_deadline = dl_se->dl_deadline;
2919 0 : attr->sched_period = dl_se->dl_period;
2920 0 : attr->sched_flags &= ~SCHED_DL_FLAGS;
2921 0 : attr->sched_flags |= dl_se->flags;
2922 0 : }
2923 :
2924 : /*
2925 : * This function validates the new parameters of a -deadline task.
2926 : * We ask for the deadline not being zero, and greater or equal
2927 : * than the runtime, as well as the period of being zero or
2928 : * greater than deadline. Furthermore, we have to be sure that
2929 : * user parameters are above the internal resolution of 1us (we
2930 : * check sched_runtime only since it is always the smaller one) and
2931 : * below 2^63 ns (we have to check both sched_deadline and
2932 : * sched_period, as the latter can be zero).
2933 : */
2934 0 : bool __checkparam_dl(const struct sched_attr *attr)
2935 : {
2936 : u64 period, max, min;
2937 :
2938 : /* special dl tasks don't actually use any parameter */
2939 0 : if (attr->sched_flags & SCHED_FLAG_SUGOV)
2940 : return true;
2941 :
2942 : /* deadline != 0 */
2943 0 : if (attr->sched_deadline == 0)
2944 : return false;
2945 :
2946 : /*
2947 : * Since we truncate DL_SCALE bits, make sure we're at least
2948 : * that big.
2949 : */
2950 0 : if (attr->sched_runtime < (1ULL << DL_SCALE))
2951 : return false;
2952 :
2953 : /*
2954 : * Since we use the MSB for wrap-around and sign issues, make
2955 : * sure it's not set (mind that period can be equal to zero).
2956 : */
2957 0 : if (attr->sched_deadline & (1ULL << 63) ||
2958 0 : attr->sched_period & (1ULL << 63))
2959 : return false;
2960 :
2961 0 : period = attr->sched_period;
2962 0 : if (!period)
2963 0 : period = attr->sched_deadline;
2964 :
2965 : /* runtime <= deadline <= period (if period != 0) */
2966 0 : if (period < attr->sched_deadline ||
2967 : attr->sched_deadline < attr->sched_runtime)
2968 : return false;
2969 :
2970 0 : max = (u64)READ_ONCE(sysctl_sched_dl_period_max) * NSEC_PER_USEC;
2971 0 : min = (u64)READ_ONCE(sysctl_sched_dl_period_min) * NSEC_PER_USEC;
2972 :
2973 0 : if (period < min || period > max)
2974 : return false;
2975 :
2976 0 : return true;
2977 : }
2978 :
2979 : /*
2980 : * This function clears the sched_dl_entity static params.
2981 : */
2982 349 : void __dl_clear_params(struct task_struct *p)
2983 : {
2984 349 : struct sched_dl_entity *dl_se = &p->dl;
2985 :
2986 349 : dl_se->dl_runtime = 0;
2987 349 : dl_se->dl_deadline = 0;
2988 349 : dl_se->dl_period = 0;
2989 349 : dl_se->flags = 0;
2990 349 : dl_se->dl_bw = 0;
2991 349 : dl_se->dl_density = 0;
2992 :
2993 349 : dl_se->dl_throttled = 0;
2994 349 : dl_se->dl_yielded = 0;
2995 349 : dl_se->dl_non_contending = 0;
2996 349 : dl_se->dl_overrun = 0;
2997 :
2998 : #ifdef CONFIG_RT_MUTEXES
2999 349 : dl_se->pi_se = dl_se;
3000 : #endif
3001 349 : }
3002 :
3003 0 : bool dl_param_changed(struct task_struct *p, const struct sched_attr *attr)
3004 : {
3005 0 : struct sched_dl_entity *dl_se = &p->dl;
3006 :
3007 0 : if (dl_se->dl_runtime != attr->sched_runtime ||
3008 0 : dl_se->dl_deadline != attr->sched_deadline ||
3009 0 : dl_se->dl_period != attr->sched_period ||
3010 0 : dl_se->flags != (attr->sched_flags & SCHED_DL_FLAGS))
3011 : return true;
3012 :
3013 0 : return false;
3014 : }
3015 :
3016 : #ifdef CONFIG_SMP
3017 : int dl_cpuset_cpumask_can_shrink(const struct cpumask *cur,
3018 : const struct cpumask *trial)
3019 : {
3020 : unsigned long flags, cap;
3021 : struct dl_bw *cur_dl_b;
3022 : int ret = 1;
3023 :
3024 : rcu_read_lock_sched();
3025 : cur_dl_b = dl_bw_of(cpumask_any(cur));
3026 : cap = __dl_bw_capacity(trial);
3027 : raw_spin_lock_irqsave(&cur_dl_b->lock, flags);
3028 : if (__dl_overflow(cur_dl_b, cap, 0, 0))
3029 : ret = 0;
3030 : raw_spin_unlock_irqrestore(&cur_dl_b->lock, flags);
3031 : rcu_read_unlock_sched();
3032 :
3033 : return ret;
3034 : }
3035 :
3036 : int dl_cpu_busy(int cpu, struct task_struct *p)
3037 : {
3038 : unsigned long flags, cap;
3039 : struct dl_bw *dl_b;
3040 : bool overflow;
3041 :
3042 : rcu_read_lock_sched();
3043 : dl_b = dl_bw_of(cpu);
3044 : raw_spin_lock_irqsave(&dl_b->lock, flags);
3045 : cap = dl_bw_capacity(cpu);
3046 : overflow = __dl_overflow(dl_b, cap, 0, p ? p->dl.dl_bw : 0);
3047 :
3048 : if (!overflow && p) {
3049 : /*
3050 : * We reserve space for this task in the destination
3051 : * root_domain, as we can't fail after this point.
3052 : * We will free resources in the source root_domain
3053 : * later on (see set_cpus_allowed_dl()).
3054 : */
3055 : __dl_add(dl_b, p->dl.dl_bw, dl_bw_cpus(cpu));
3056 : }
3057 :
3058 : raw_spin_unlock_irqrestore(&dl_b->lock, flags);
3059 : rcu_read_unlock_sched();
3060 :
3061 : return overflow ? -EBUSY : 0;
3062 : }
3063 : #endif
3064 :
3065 : #ifdef CONFIG_SCHED_DEBUG
3066 0 : void print_dl_stats(struct seq_file *m, int cpu)
3067 : {
3068 0 : print_dl_rq(m, cpu, &cpu_rq(cpu)->dl);
3069 0 : }
3070 : #endif /* CONFIG_SCHED_DEBUG */
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