root/kernel/sched/rt.c

DEFINITIONS

1. sched_rt_period_timer
2. init_rt_bandwidth
3. start_rt_bandwidth
4. init_rt_rq
5. destroy_rt_bandwidth
6. rt_task_of
7. rq_of_rt_rq
8. rt_rq_of_se
9. rq_of_rt_se
10. free_rt_sched_group
11. init_tg_rt_entry
12. alloc_rt_sched_group
13. rt_task_of
14. rq_of_rt_rq
15. rq_of_rt_se
16. rt_rq_of_se
17. free_rt_sched_group
18. alloc_rt_sched_group
19. need_pull_rt_task
20. rt_overloaded
21. rt_set_overload
22. rt_clear_overload
23. update_rt_migration
24. inc_rt_migration
25. dec_rt_migration
26. has_pushable_tasks
27. rt_queue_push_tasks
28. rt_queue_pull_task
29. enqueue_pushable_task
30. dequeue_pushable_task
31. enqueue_pushable_task
32. dequeue_pushable_task
33. inc_rt_migration
34. dec_rt_migration
35. need_pull_rt_task
36. pull_rt_task
37. rt_queue_push_tasks
38. on_rt_rq
39. sched_rt_runtime
40. sched_rt_period
41. next_task_group
42. group_rt_rq
43. sched_rt_rq_enqueue
44. sched_rt_rq_dequeue
45. rt_rq_throttled
46. rt_se_boosted
47. sched_rt_period_mask
48. sched_rt_period_mask
49. sched_rt_period_rt_rq
50. sched_rt_bandwidth
51. sched_rt_runtime
52. sched_rt_period
53. group_rt_rq
54. sched_rt_rq_enqueue
55. sched_rt_rq_dequeue
56. rt_rq_throttled
57. sched_rt_period_mask
58. sched_rt_period_rt_rq
59. sched_rt_bandwidth
60. sched_rt_bandwidth_account
61. do_balance_runtime
62. __disable_runtime
63. __enable_runtime
64. balance_runtime
65. balance_runtime
66. do_sched_rt_period_timer
67. rt_se_prio
68. sched_rt_runtime_exceeded
69. update_curr_rt
70. dequeue_top_rt_rq
71. enqueue_top_rt_rq
72. inc_rt_prio_smp
73. dec_rt_prio_smp
74. inc_rt_prio_smp
75. dec_rt_prio_smp
76. inc_rt_prio
77. dec_rt_prio
78. inc_rt_prio
79. dec_rt_prio
80. inc_rt_group
81. dec_rt_group
82. inc_rt_group
83. dec_rt_group
84. rt_se_nr_running
85. rt_se_rr_nr_running
86. inc_rt_tasks
87. dec_rt_tasks
88. move_entity
89. __delist_rt_entity
90. __enqueue_rt_entity
91. __dequeue_rt_entity
92. dequeue_rt_stack
93. enqueue_rt_entity
94. dequeue_rt_entity
95. enqueue_task_rt
96. dequeue_task_rt
97. requeue_rt_entity
98. requeue_task_rt
99. yield_task_rt
100. select_task_rq_rt
101. check_preempt_equal_prio
102. balance_rt
103. check_preempt_curr_rt
104. set_next_task_rt
105. pick_next_rt_entity
106. _pick_next_task_rt
107. pick_next_task_rt
108. put_prev_task_rt
109. pick_rt_task
110. pick_highest_pushable_task
111. find_lowest_rq
112. find_lock_lowest_rq
113. pick_next_pushable_task
114. push_rt_task
115. push_rt_tasks
116. rto_next_cpu
117. rto_start_trylock
118. rto_start_unlock
119. tell_cpu_to_push
120. rto_push_irq_work_func
121. pull_rt_task
122. task_woken_rt
123. rq_online_rt
124. rq_offline_rt
125. switched_from_rt
126. init_sched_rt_class
127. switched_to_rt
128. prio_changed_rt
129. watchdog
130. watchdog
131. task_tick_rt
132. get_rr_interval_rt
133. tg_has_rt_tasks
134. tg_rt_schedulable
135. __rt_schedulable
136. tg_set_rt_bandwidth
137. sched_group_set_rt_runtime
138. sched_group_rt_runtime
139. sched_group_set_rt_period
140. sched_group_rt_period
141. sched_rt_global_constraints
142. sched_rt_can_attach
143. sched_rt_global_constraints
144. sched_rt_global_validate
145. sched_rt_do_global
146. sched_rt_handler
147. sched_rr_handler
148. print_rt_stats

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