perf: Drop the obsolete profile naming for trace events
[linux-2.6.git] / kernel / sched_rt.c
1 /*
2  * Real-Time Scheduling Class (mapped to the SCHED_FIFO and SCHED_RR
3  * policies)
4  */
5
6 #ifdef CONFIG_RT_GROUP_SCHED
7
8 #define rt_entity_is_task(rt_se) (!(rt_se)->my_q)
9
10 static inline struct task_struct *rt_task_of(struct sched_rt_entity *rt_se)
11 {
12 #ifdef CONFIG_SCHED_DEBUG
13         WARN_ON_ONCE(!rt_entity_is_task(rt_se));
14 #endif
15         return container_of(rt_se, struct task_struct, rt);
16 }
17
18 static inline struct rq *rq_of_rt_rq(struct rt_rq *rt_rq)
19 {
20         return rt_rq->rq;
21 }
22
23 static inline struct rt_rq *rt_rq_of_se(struct sched_rt_entity *rt_se)
24 {
25         return rt_se->rt_rq;
26 }
27
28 #else /* CONFIG_RT_GROUP_SCHED */
29
30 #define rt_entity_is_task(rt_se) (1)
31
32 static inline struct task_struct *rt_task_of(struct sched_rt_entity *rt_se)
33 {
34         return container_of(rt_se, struct task_struct, rt);
35 }
36
37 static inline struct rq *rq_of_rt_rq(struct rt_rq *rt_rq)
38 {
39         return container_of(rt_rq, struct rq, rt);
40 }
41
42 static inline struct rt_rq *rt_rq_of_se(struct sched_rt_entity *rt_se)
43 {
44         struct task_struct *p = rt_task_of(rt_se);
45         struct rq *rq = task_rq(p);
46
47         return &rq->rt;
48 }
49
50 #endif /* CONFIG_RT_GROUP_SCHED */
51
52 #ifdef CONFIG_SMP
53
54 static inline int rt_overloaded(struct rq *rq)
55 {
56         return atomic_read(&rq->rd->rto_count);
57 }
58
59 static inline void rt_set_overload(struct rq *rq)
60 {
61         if (!rq->online)
62                 return;
63
64         cpumask_set_cpu(rq->cpu, rq->rd->rto_mask);
65         /*
66          * Make sure the mask is visible before we set
67          * the overload count. That is checked to determine
68          * if we should look at the mask. It would be a shame
69          * if we looked at the mask, but the mask was not
70          * updated yet.
71          */
72         wmb();
73         atomic_inc(&rq->rd->rto_count);
74 }
75
76 static inline void rt_clear_overload(struct rq *rq)
77 {
78         if (!rq->online)
79                 return;
80
81         /* the order here really doesn't matter */
82         atomic_dec(&rq->rd->rto_count);
83         cpumask_clear_cpu(rq->cpu, rq->rd->rto_mask);
84 }
85
86 static void update_rt_migration(struct rt_rq *rt_rq)
87 {
88         if (rt_rq->rt_nr_migratory && rt_rq->rt_nr_total > 1) {
89                 if (!rt_rq->overloaded) {
90                         rt_set_overload(rq_of_rt_rq(rt_rq));
91                         rt_rq->overloaded = 1;
92                 }
93         } else if (rt_rq->overloaded) {
94                 rt_clear_overload(rq_of_rt_rq(rt_rq));
95                 rt_rq->overloaded = 0;
96         }
97 }
98
99 static void inc_rt_migration(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
100 {
101         if (!rt_entity_is_task(rt_se))
102                 return;
103
104         rt_rq = &rq_of_rt_rq(rt_rq)->rt;
105
106         rt_rq->rt_nr_total++;
107         if (rt_se->nr_cpus_allowed > 1)
108                 rt_rq->rt_nr_migratory++;
109
110         update_rt_migration(rt_rq);
111 }
112
113 static void dec_rt_migration(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
114 {
115         if (!rt_entity_is_task(rt_se))
116                 return;
117
118         rt_rq = &rq_of_rt_rq(rt_rq)->rt;
119
120         rt_rq->rt_nr_total--;
121         if (rt_se->nr_cpus_allowed > 1)
122                 rt_rq->rt_nr_migratory--;
123
124         update_rt_migration(rt_rq);
125 }
126
127 static void enqueue_pushable_task(struct rq *rq, struct task_struct *p)
128 {
129         plist_del(&p->pushable_tasks, &rq->rt.pushable_tasks);
130         plist_node_init(&p->pushable_tasks, p->prio);
131         plist_add(&p->pushable_tasks, &rq->rt.pushable_tasks);
132 }
133
134 static void dequeue_pushable_task(struct rq *rq, struct task_struct *p)
135 {
136         plist_del(&p->pushable_tasks, &rq->rt.pushable_tasks);
137 }
138
139 static inline int has_pushable_tasks(struct rq *rq)
140 {
141         return !plist_head_empty(&rq->rt.pushable_tasks);
142 }
143
144 #else
145
146 static inline void enqueue_pushable_task(struct rq *rq, struct task_struct *p)
147 {
148 }
149
150 static inline void dequeue_pushable_task(struct rq *rq, struct task_struct *p)
151 {
152 }
153
154 static inline
155 void inc_rt_migration(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
156 {
157 }
158
159 static inline
160 void dec_rt_migration(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
161 {
162 }
163
164 #endif /* CONFIG_SMP */
165
166 static inline int on_rt_rq(struct sched_rt_entity *rt_se)
167 {
168         return !list_empty(&rt_se->run_list);
169 }
170
171 #ifdef CONFIG_RT_GROUP_SCHED
172
173 static inline u64 sched_rt_runtime(struct rt_rq *rt_rq)
174 {
175         if (!rt_rq->tg)
176                 return RUNTIME_INF;
177
178         return rt_rq->rt_runtime;
179 }
180
181 static inline u64 sched_rt_period(struct rt_rq *rt_rq)
182 {
183         return ktime_to_ns(rt_rq->tg->rt_bandwidth.rt_period);
184 }
185
186 #define for_each_leaf_rt_rq(rt_rq, rq) \
187         list_for_each_entry_rcu(rt_rq, &rq->leaf_rt_rq_list, leaf_rt_rq_list)
188
189 #define for_each_sched_rt_entity(rt_se) \
190         for (; rt_se; rt_se = rt_se->parent)
191
192 static inline struct rt_rq *group_rt_rq(struct sched_rt_entity *rt_se)
193 {
194         return rt_se->my_q;
195 }
196
197 static void enqueue_rt_entity(struct sched_rt_entity *rt_se, bool head);
198 static void dequeue_rt_entity(struct sched_rt_entity *rt_se);
199
200 static void sched_rt_rq_enqueue(struct rt_rq *rt_rq)
201 {
202         int this_cpu = smp_processor_id();
203         struct task_struct *curr = rq_of_rt_rq(rt_rq)->curr;
204         struct sched_rt_entity *rt_se;
205
206         rt_se = rt_rq->tg->rt_se[this_cpu];
207
208         if (rt_rq->rt_nr_running) {
209                 if (rt_se && !on_rt_rq(rt_se))
210                         enqueue_rt_entity(rt_se, false);
211                 if (rt_rq->highest_prio.curr < curr->prio)
212                         resched_task(curr);
213         }
214 }
215
216 static void sched_rt_rq_dequeue(struct rt_rq *rt_rq)
217 {
218         int this_cpu = smp_processor_id();
219         struct sched_rt_entity *rt_se;
220
221         rt_se = rt_rq->tg->rt_se[this_cpu];
222
223         if (rt_se && on_rt_rq(rt_se))
224                 dequeue_rt_entity(rt_se);
225 }
226
227 static inline int rt_rq_throttled(struct rt_rq *rt_rq)
228 {
229         return rt_rq->rt_throttled && !rt_rq->rt_nr_boosted;
230 }
231
232 static int rt_se_boosted(struct sched_rt_entity *rt_se)
233 {
234         struct rt_rq *rt_rq = group_rt_rq(rt_se);
235         struct task_struct *p;
236
237         if (rt_rq)
238                 return !!rt_rq->rt_nr_boosted;
239
240         p = rt_task_of(rt_se);
241         return p->prio != p->normal_prio;
242 }
243
244 #ifdef CONFIG_SMP
245 static inline const struct cpumask *sched_rt_period_mask(void)
246 {
247         return cpu_rq(smp_processor_id())->rd->span;
248 }
249 #else
250 static inline const struct cpumask *sched_rt_period_mask(void)
251 {
252         return cpu_online_mask;
253 }
254 #endif
255
256 static inline
257 struct rt_rq *sched_rt_period_rt_rq(struct rt_bandwidth *rt_b, int cpu)
258 {
259         return container_of(rt_b, struct task_group, rt_bandwidth)->rt_rq[cpu];
260 }
261
262 static inline struct rt_bandwidth *sched_rt_bandwidth(struct rt_rq *rt_rq)
263 {
264         return &rt_rq->tg->rt_bandwidth;
265 }
266
267 #else /* !CONFIG_RT_GROUP_SCHED */
268
269 static inline u64 sched_rt_runtime(struct rt_rq *rt_rq)
270 {
271         return rt_rq->rt_runtime;
272 }
273
274 static inline u64 sched_rt_period(struct rt_rq *rt_rq)
275 {
276         return ktime_to_ns(def_rt_bandwidth.rt_period);
277 }
278
279 #define for_each_leaf_rt_rq(rt_rq, rq) \
280         for (rt_rq = &rq->rt; rt_rq; rt_rq = NULL)
281
282 #define for_each_sched_rt_entity(rt_se) \
283         for (; rt_se; rt_se = NULL)
284
285 static inline struct rt_rq *group_rt_rq(struct sched_rt_entity *rt_se)
286 {
287         return NULL;
288 }
289
290 static inline void sched_rt_rq_enqueue(struct rt_rq *rt_rq)
291 {
292         if (rt_rq->rt_nr_running)
293                 resched_task(rq_of_rt_rq(rt_rq)->curr);
294 }
295
296 static inline void sched_rt_rq_dequeue(struct rt_rq *rt_rq)
297 {
298 }
299
300 static inline int rt_rq_throttled(struct rt_rq *rt_rq)
301 {
302         return rt_rq->rt_throttled;
303 }
304
305 static inline const struct cpumask *sched_rt_period_mask(void)
306 {
307         return cpu_online_mask;
308 }
309
310 static inline
311 struct rt_rq *sched_rt_period_rt_rq(struct rt_bandwidth *rt_b, int cpu)
312 {
313         return &cpu_rq(cpu)->rt;
314 }
315
316 static inline struct rt_bandwidth *sched_rt_bandwidth(struct rt_rq *rt_rq)
317 {
318         return &def_rt_bandwidth;
319 }
320
321 #endif /* CONFIG_RT_GROUP_SCHED */
322
323 #ifdef CONFIG_SMP
324 /*
325  * We ran out of runtime, see if we can borrow some from our neighbours.
326  */
327 static int do_balance_runtime(struct rt_rq *rt_rq)
328 {
329         struct rt_bandwidth *rt_b = sched_rt_bandwidth(rt_rq);
330         struct root_domain *rd = cpu_rq(smp_processor_id())->rd;
331         int i, weight, more = 0;
332         u64 rt_period;
333
334         weight = cpumask_weight(rd->span);
335
336         raw_spin_lock(&rt_b->rt_runtime_lock);
337         rt_period = ktime_to_ns(rt_b->rt_period);
338         for_each_cpu(i, rd->span) {
339                 struct rt_rq *iter = sched_rt_period_rt_rq(rt_b, i);
340                 s64 diff;
341
342                 if (iter == rt_rq)
343                         continue;
344
345                 raw_spin_lock(&iter->rt_runtime_lock);
346                 /*
347                  * Either all rqs have inf runtime and there's nothing to steal
348                  * or __disable_runtime() below sets a specific rq to inf to
349                  * indicate its been disabled and disalow stealing.
350                  */
351                 if (iter->rt_runtime == RUNTIME_INF)
352                         goto next;
353
354                 /*
355                  * From runqueues with spare time, take 1/n part of their
356                  * spare time, but no more than our period.
357                  */
358                 diff = iter->rt_runtime - iter->rt_time;
359                 if (diff > 0) {
360                         diff = div_u64((u64)diff, weight);
361                         if (rt_rq->rt_runtime + diff > rt_period)
362                                 diff = rt_period - rt_rq->rt_runtime;
363                         iter->rt_runtime -= diff;
364                         rt_rq->rt_runtime += diff;
365                         more = 1;
366                         if (rt_rq->rt_runtime == rt_period) {
367                                 raw_spin_unlock(&iter->rt_runtime_lock);
368                                 break;
369                         }
370                 }
371 next:
372                 raw_spin_unlock(&iter->rt_runtime_lock);
373         }
374         raw_spin_unlock(&rt_b->rt_runtime_lock);
375
376         return more;
377 }
378
379 /*
380  * Ensure this RQ takes back all the runtime it lend to its neighbours.
381  */
382 static void __disable_runtime(struct rq *rq)
383 {
384         struct root_domain *rd = rq->rd;
385         struct rt_rq *rt_rq;
386
387         if (unlikely(!scheduler_running))
388                 return;
389
390         for_each_leaf_rt_rq(rt_rq, rq) {
391                 struct rt_bandwidth *rt_b = sched_rt_bandwidth(rt_rq);
392                 s64 want;
393                 int i;
394
395                 raw_spin_lock(&rt_b->rt_runtime_lock);
396                 raw_spin_lock(&rt_rq->rt_runtime_lock);
397                 /*
398                  * Either we're all inf and nobody needs to borrow, or we're
399                  * already disabled and thus have nothing to do, or we have
400                  * exactly the right amount of runtime to take out.
401                  */
402                 if (rt_rq->rt_runtime == RUNTIME_INF ||
403                                 rt_rq->rt_runtime == rt_b->rt_runtime)
404                         goto balanced;
405                 raw_spin_unlock(&rt_rq->rt_runtime_lock);
406
407                 /*
408                  * Calculate the difference between what we started out with
409                  * and what we current have, that's the amount of runtime
410                  * we lend and now have to reclaim.
411                  */
412                 want = rt_b->rt_runtime - rt_rq->rt_runtime;
413
414                 /*
415                  * Greedy reclaim, take back as much as we can.
416                  */
417                 for_each_cpu(i, rd->span) {
418                         struct rt_rq *iter = sched_rt_period_rt_rq(rt_b, i);
419                         s64 diff;
420
421                         /*
422                          * Can't reclaim from ourselves or disabled runqueues.
423                          */
424                         if (iter == rt_rq || iter->rt_runtime == RUNTIME_INF)
425                                 continue;
426
427                         raw_spin_lock(&iter->rt_runtime_lock);
428                         if (want > 0) {
429                                 diff = min_t(s64, iter->rt_runtime, want);
430                                 iter->rt_runtime -= diff;
431                                 want -= diff;
432                         } else {
433                                 iter->rt_runtime -= want;
434                                 want -= want;
435                         }
436                         raw_spin_unlock(&iter->rt_runtime_lock);
437
438                         if (!want)
439                                 break;
440                 }
441
442                 raw_spin_lock(&rt_rq->rt_runtime_lock);
443                 /*
444                  * We cannot be left wanting - that would mean some runtime
445                  * leaked out of the system.
446                  */
447                 BUG_ON(want);
448 balanced:
449                 /*
450                  * Disable all the borrow logic by pretending we have inf
451                  * runtime - in which case borrowing doesn't make sense.
452                  */
453                 rt_rq->rt_runtime = RUNTIME_INF;
454                 raw_spin_unlock(&rt_rq->rt_runtime_lock);
455                 raw_spin_unlock(&rt_b->rt_runtime_lock);
456         }
457 }
458
459 static void disable_runtime(struct rq *rq)
460 {
461         unsigned long flags;
462
463         raw_spin_lock_irqsave(&rq->lock, flags);
464         __disable_runtime(rq);
465         raw_spin_unlock_irqrestore(&rq->lock, flags);
466 }
467
468 static void __enable_runtime(struct rq *rq)
469 {
470         struct rt_rq *rt_rq;
471
472         if (unlikely(!scheduler_running))
473                 return;
474
475         /*
476          * Reset each runqueue's bandwidth settings
477          */
478         for_each_leaf_rt_rq(rt_rq, rq) {
479                 struct rt_bandwidth *rt_b = sched_rt_bandwidth(rt_rq);
480
481                 raw_spin_lock(&rt_b->rt_runtime_lock);
482                 raw_spin_lock(&rt_rq->rt_runtime_lock);
483                 rt_rq->rt_runtime = rt_b->rt_runtime;
484                 rt_rq->rt_time = 0;
485                 rt_rq->rt_throttled = 0;
486                 raw_spin_unlock(&rt_rq->rt_runtime_lock);
487                 raw_spin_unlock(&rt_b->rt_runtime_lock);
488         }
489 }
490
491 static void enable_runtime(struct rq *rq)
492 {
493         unsigned long flags;
494
495         raw_spin_lock_irqsave(&rq->lock, flags);
496         __enable_runtime(rq);
497         raw_spin_unlock_irqrestore(&rq->lock, flags);
498 }
499
500 static int balance_runtime(struct rt_rq *rt_rq)
501 {
502         int more = 0;
503
504         if (rt_rq->rt_time > rt_rq->rt_runtime) {
505                 raw_spin_unlock(&rt_rq->rt_runtime_lock);
506                 more = do_balance_runtime(rt_rq);
507                 raw_spin_lock(&rt_rq->rt_runtime_lock);
508         }
509
510         return more;
511 }
512 #else /* !CONFIG_SMP */
513 static inline int balance_runtime(struct rt_rq *rt_rq)
514 {
515         return 0;
516 }
517 #endif /* CONFIG_SMP */
518
519 static int do_sched_rt_period_timer(struct rt_bandwidth *rt_b, int overrun)
520 {
521         int i, idle = 1;
522         const struct cpumask *span;
523
524         if (!rt_bandwidth_enabled() || rt_b->rt_runtime == RUNTIME_INF)
525                 return 1;
526
527         span = sched_rt_period_mask();
528         for_each_cpu(i, span) {
529                 int enqueue = 0;
530                 struct rt_rq *rt_rq = sched_rt_period_rt_rq(rt_b, i);
531                 struct rq *rq = rq_of_rt_rq(rt_rq);
532
533                 raw_spin_lock(&rq->lock);
534                 if (rt_rq->rt_time) {
535                         u64 runtime;
536
537                         raw_spin_lock(&rt_rq->rt_runtime_lock);
538                         if (rt_rq->rt_throttled)
539                                 balance_runtime(rt_rq);
540                         runtime = rt_rq->rt_runtime;
541                         rt_rq->rt_time -= min(rt_rq->rt_time, overrun*runtime);
542                         if (rt_rq->rt_throttled && rt_rq->rt_time < runtime) {
543                                 rt_rq->rt_throttled = 0;
544                                 enqueue = 1;
545                         }
546                         if (rt_rq->rt_time || rt_rq->rt_nr_running)
547                                 idle = 0;
548                         raw_spin_unlock(&rt_rq->rt_runtime_lock);
549                 } else if (rt_rq->rt_nr_running)
550                         idle = 0;
551
552                 if (enqueue)
553                         sched_rt_rq_enqueue(rt_rq);
554                 raw_spin_unlock(&rq->lock);
555         }
556
557         return idle;
558 }
559
560 static inline int rt_se_prio(struct sched_rt_entity *rt_se)
561 {
562 #ifdef CONFIG_RT_GROUP_SCHED
563         struct rt_rq *rt_rq = group_rt_rq(rt_se);
564
565         if (rt_rq)
566                 return rt_rq->highest_prio.curr;
567 #endif
568
569         return rt_task_of(rt_se)->prio;
570 }
571
572 static int sched_rt_runtime_exceeded(struct rt_rq *rt_rq)
573 {
574         u64 runtime = sched_rt_runtime(rt_rq);
575
576         if (rt_rq->rt_throttled)
577                 return rt_rq_throttled(rt_rq);
578
579         if (sched_rt_runtime(rt_rq) >= sched_rt_period(rt_rq))
580                 return 0;
581
582         balance_runtime(rt_rq);
583         runtime = sched_rt_runtime(rt_rq);
584         if (runtime == RUNTIME_INF)
585                 return 0;
586
587         if (rt_rq->rt_time > runtime) {
588                 rt_rq->rt_throttled = 1;
589                 if (rt_rq_throttled(rt_rq)) {
590                         sched_rt_rq_dequeue(rt_rq);
591                         return 1;
592                 }
593         }
594
595         return 0;
596 }
597
598 /*
599  * Update the current task's runtime statistics. Skip current tasks that
600  * are not in our scheduling class.
601  */
602 static void update_curr_rt(struct rq *rq)
603 {
604         struct task_struct *curr = rq->curr;
605         struct sched_rt_entity *rt_se = &curr->rt;
606         struct rt_rq *rt_rq = rt_rq_of_se(rt_se);
607         u64 delta_exec;
608
609         if (!task_has_rt_policy(curr))
610                 return;
611
612         delta_exec = rq->clock - curr->se.exec_start;
613         if (unlikely((s64)delta_exec < 0))
614                 delta_exec = 0;
615
616         schedstat_set(curr->se.exec_max, max(curr->se.exec_max, delta_exec));
617
618         curr->se.sum_exec_runtime += delta_exec;
619         account_group_exec_runtime(curr, delta_exec);
620
621         curr->se.exec_start = rq->clock;
622         cpuacct_charge(curr, delta_exec);
623
624         sched_rt_avg_update(rq, delta_exec);
625
626         if (!rt_bandwidth_enabled())
627                 return;
628
629         for_each_sched_rt_entity(rt_se) {
630                 rt_rq = rt_rq_of_se(rt_se);
631
632                 if (sched_rt_runtime(rt_rq) != RUNTIME_INF) {
633                         raw_spin_lock(&rt_rq->rt_runtime_lock);
634                         rt_rq->rt_time += delta_exec;
635                         if (sched_rt_runtime_exceeded(rt_rq))
636                                 resched_task(curr);
637                         raw_spin_unlock(&rt_rq->rt_runtime_lock);
638                 }
639         }
640 }
641
642 #if defined CONFIG_SMP
643
644 static struct task_struct *pick_next_highest_task_rt(struct rq *rq, int cpu);
645
646 static inline int next_prio(struct rq *rq)
647 {
648         struct task_struct *next = pick_next_highest_task_rt(rq, rq->cpu);
649
650         if (next && rt_prio(next->prio))
651                 return next->prio;
652         else
653                 return MAX_RT_PRIO;
654 }
655
656 static void
657 inc_rt_prio_smp(struct rt_rq *rt_rq, int prio, int prev_prio)
658 {
659         struct rq *rq = rq_of_rt_rq(rt_rq);
660
661         if (prio < prev_prio) {
662
663                 /*
664                  * If the new task is higher in priority than anything on the
665                  * run-queue, we know that the previous high becomes our
666                  * next-highest.
667                  */
668                 rt_rq->highest_prio.next = prev_prio;
669
670                 if (rq->online)
671                         cpupri_set(&rq->rd->cpupri, rq->cpu, prio);
672
673         } else if (prio == rt_rq->highest_prio.curr)
674                 /*
675                  * If the next task is equal in priority to the highest on
676                  * the run-queue, then we implicitly know that the next highest
677                  * task cannot be any lower than current
678                  */
679                 rt_rq->highest_prio.next = prio;
680         else if (prio < rt_rq->highest_prio.next)
681                 /*
682                  * Otherwise, we need to recompute next-highest
683                  */
684                 rt_rq->highest_prio.next = next_prio(rq);
685 }
686
687 static void
688 dec_rt_prio_smp(struct rt_rq *rt_rq, int prio, int prev_prio)
689 {
690         struct rq *rq = rq_of_rt_rq(rt_rq);
691
692         if (rt_rq->rt_nr_running && (prio <= rt_rq->highest_prio.next))
693                 rt_rq->highest_prio.next = next_prio(rq);
694
695         if (rq->online && rt_rq->highest_prio.curr != prev_prio)
696                 cpupri_set(&rq->rd->cpupri, rq->cpu, rt_rq->highest_prio.curr);
697 }
698
699 #else /* CONFIG_SMP */
700
701 static inline
702 void inc_rt_prio_smp(struct rt_rq *rt_rq, int prio, int prev_prio) {}
703 static inline
704 void dec_rt_prio_smp(struct rt_rq *rt_rq, int prio, int prev_prio) {}
705
706 #endif /* CONFIG_SMP */
707
708 #if defined CONFIG_SMP || defined CONFIG_RT_GROUP_SCHED
709 static void
710 inc_rt_prio(struct rt_rq *rt_rq, int prio)
711 {
712         int prev_prio = rt_rq->highest_prio.curr;
713
714         if (prio < prev_prio)
715                 rt_rq->highest_prio.curr = prio;
716
717         inc_rt_prio_smp(rt_rq, prio, prev_prio);
718 }
719
720 static void
721 dec_rt_prio(struct rt_rq *rt_rq, int prio)
722 {
723         int prev_prio = rt_rq->highest_prio.curr;
724
725         if (rt_rq->rt_nr_running) {
726
727                 WARN_ON(prio < prev_prio);
728
729                 /*
730                  * This may have been our highest task, and therefore
731                  * we may have some recomputation to do
732                  */
733                 if (prio == prev_prio) {
734                         struct rt_prio_array *array = &rt_rq->active;
735
736                         rt_rq->highest_prio.curr =
737                                 sched_find_first_bit(array->bitmap);
738                 }
739
740         } else
741                 rt_rq->highest_prio.curr = MAX_RT_PRIO;
742
743         dec_rt_prio_smp(rt_rq, prio, prev_prio);
744 }
745
746 #else
747
748 static inline void inc_rt_prio(struct rt_rq *rt_rq, int prio) {}
749 static inline void dec_rt_prio(struct rt_rq *rt_rq, int prio) {}
750
751 #endif /* CONFIG_SMP || CONFIG_RT_GROUP_SCHED */
752
753 #ifdef CONFIG_RT_GROUP_SCHED
754
755 static void
756 inc_rt_group(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
757 {
758         if (rt_se_boosted(rt_se))
759                 rt_rq->rt_nr_boosted++;
760
761         if (rt_rq->tg)
762                 start_rt_bandwidth(&rt_rq->tg->rt_bandwidth);
763 }
764
765 static void
766 dec_rt_group(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
767 {
768         if (rt_se_boosted(rt_se))
769                 rt_rq->rt_nr_boosted--;
770
771         WARN_ON(!rt_rq->rt_nr_running && rt_rq->rt_nr_boosted);
772 }
773
774 #else /* CONFIG_RT_GROUP_SCHED */
775
776 static void
777 inc_rt_group(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
778 {
779         start_rt_bandwidth(&def_rt_bandwidth);
780 }
781
782 static inline
783 void dec_rt_group(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq) {}
784
785 #endif /* CONFIG_RT_GROUP_SCHED */
786
787 static inline
788 void inc_rt_tasks(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
789 {
790         int prio = rt_se_prio(rt_se);
791
792         WARN_ON(!rt_prio(prio));
793         rt_rq->rt_nr_running++;
794
795         inc_rt_prio(rt_rq, prio);
796         inc_rt_migration(rt_se, rt_rq);
797         inc_rt_group(rt_se, rt_rq);
798 }
799
800 static inline
801 void dec_rt_tasks(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
802 {
803         WARN_ON(!rt_prio(rt_se_prio(rt_se)));
804         WARN_ON(!rt_rq->rt_nr_running);
805         rt_rq->rt_nr_running--;
806
807         dec_rt_prio(rt_rq, rt_se_prio(rt_se));
808         dec_rt_migration(rt_se, rt_rq);
809         dec_rt_group(rt_se, rt_rq);
810 }
811
812 static void __enqueue_rt_entity(struct sched_rt_entity *rt_se, bool head)
813 {
814         struct rt_rq *rt_rq = rt_rq_of_se(rt_se);
815         struct rt_prio_array *array = &rt_rq->active;
816         struct rt_rq *group_rq = group_rt_rq(rt_se);
817         struct list_head *queue = array->queue + rt_se_prio(rt_se);
818
819         /*
820          * Don't enqueue the group if its throttled, or when empty.
821          * The latter is a consequence of the former when a child group
822          * get throttled and the current group doesn't have any other
823          * active members.
824          */
825         if (group_rq && (rt_rq_throttled(group_rq) || !group_rq->rt_nr_running))
826                 return;
827
828         if (head)
829                 list_add(&rt_se->run_list, queue);
830         else
831                 list_add_tail(&rt_se->run_list, queue);
832         __set_bit(rt_se_prio(rt_se), array->bitmap);
833
834         inc_rt_tasks(rt_se, rt_rq);
835 }
836
837 static void __dequeue_rt_entity(struct sched_rt_entity *rt_se)
838 {
839         struct rt_rq *rt_rq = rt_rq_of_se(rt_se);
840         struct rt_prio_array *array = &rt_rq->active;
841
842         list_del_init(&rt_se->run_list);
843         if (list_empty(array->queue + rt_se_prio(rt_se)))
844                 __clear_bit(rt_se_prio(rt_se), array->bitmap);
845
846         dec_rt_tasks(rt_se, rt_rq);
847 }
848
849 /*
850  * Because the prio of an upper entry depends on the lower
851  * entries, we must remove entries top - down.
852  */
853 static void dequeue_rt_stack(struct sched_rt_entity *rt_se)
854 {
855         struct sched_rt_entity *back = NULL;
856
857         for_each_sched_rt_entity(rt_se) {
858                 rt_se->back = back;
859                 back = rt_se;
860         }
861
862         for (rt_se = back; rt_se; rt_se = rt_se->back) {
863                 if (on_rt_rq(rt_se))
864                         __dequeue_rt_entity(rt_se);
865         }
866 }
867
868 static void enqueue_rt_entity(struct sched_rt_entity *rt_se, bool head)
869 {
870         dequeue_rt_stack(rt_se);
871         for_each_sched_rt_entity(rt_se)
872                 __enqueue_rt_entity(rt_se, head);
873 }
874
875 static void dequeue_rt_entity(struct sched_rt_entity *rt_se)
876 {
877         dequeue_rt_stack(rt_se);
878
879         for_each_sched_rt_entity(rt_se) {
880                 struct rt_rq *rt_rq = group_rt_rq(rt_se);
881
882                 if (rt_rq && rt_rq->rt_nr_running)
883                         __enqueue_rt_entity(rt_se, false);
884         }
885 }
886
887 /*
888  * Adding/removing a task to/from a priority array:
889  */
890 static void
891 enqueue_task_rt(struct rq *rq, struct task_struct *p, int wakeup, bool head)
892 {
893         struct sched_rt_entity *rt_se = &p->rt;
894
895         if (wakeup)
896                 rt_se->timeout = 0;
897
898         enqueue_rt_entity(rt_se, head);
899
900         if (!task_current(rq, p) && p->rt.nr_cpus_allowed > 1)
901                 enqueue_pushable_task(rq, p);
902 }
903
904 static void dequeue_task_rt(struct rq *rq, struct task_struct *p, int sleep)
905 {
906         struct sched_rt_entity *rt_se = &p->rt;
907
908         update_curr_rt(rq);
909         dequeue_rt_entity(rt_se);
910
911         dequeue_pushable_task(rq, p);
912 }
913
914 /*
915  * Put task to the end of the run list without the overhead of dequeue
916  * followed by enqueue.
917  */
918 static void
919 requeue_rt_entity(struct rt_rq *rt_rq, struct sched_rt_entity *rt_se, int head)
920 {
921         if (on_rt_rq(rt_se)) {
922                 struct rt_prio_array *array = &rt_rq->active;
923                 struct list_head *queue = array->queue + rt_se_prio(rt_se);
924
925                 if (head)
926                         list_move(&rt_se->run_list, queue);
927                 else
928                         list_move_tail(&rt_se->run_list, queue);
929         }
930 }
931
932 static void requeue_task_rt(struct rq *rq, struct task_struct *p, int head)
933 {
934         struct sched_rt_entity *rt_se = &p->rt;
935         struct rt_rq *rt_rq;
936
937         for_each_sched_rt_entity(rt_se) {
938                 rt_rq = rt_rq_of_se(rt_se);
939                 requeue_rt_entity(rt_rq, rt_se, head);
940         }
941 }
942
943 static void yield_task_rt(struct rq *rq)
944 {
945         requeue_task_rt(rq, rq->curr, 0);
946 }
947
948 #ifdef CONFIG_SMP
949 static int find_lowest_rq(struct task_struct *task);
950
951 static int select_task_rq_rt(struct task_struct *p, int sd_flag, int flags)
952 {
953         struct rq *rq = task_rq(p);
954
955         if (sd_flag != SD_BALANCE_WAKE)
956                 return smp_processor_id();
957
958         /*
959          * If the current task is an RT task, then
960          * try to see if we can wake this RT task up on another
961          * runqueue. Otherwise simply start this RT task
962          * on its current runqueue.
963          *
964          * We want to avoid overloading runqueues. Even if
965          * the RT task is of higher priority than the current RT task.
966          * RT tasks behave differently than other tasks. If
967          * one gets preempted, we try to push it off to another queue.
968          * So trying to keep a preempting RT task on the same
969          * cache hot CPU will force the running RT task to
970          * a cold CPU. So we waste all the cache for the lower
971          * RT task in hopes of saving some of a RT task
972          * that is just being woken and probably will have
973          * cold cache anyway.
974          */
975         if (unlikely(rt_task(rq->curr)) &&
976             (p->rt.nr_cpus_allowed > 1)) {
977                 int cpu = find_lowest_rq(p);
978
979                 return (cpu == -1) ? task_cpu(p) : cpu;
980         }
981
982         /*
983          * Otherwise, just let it ride on the affined RQ and the
984          * post-schedule router will push the preempted task away
985          */
986         return task_cpu(p);
987 }
988
989 static void check_preempt_equal_prio(struct rq *rq, struct task_struct *p)
990 {
991         if (rq->curr->rt.nr_cpus_allowed == 1)
992                 return;
993
994         if (p->rt.nr_cpus_allowed != 1
995             && cpupri_find(&rq->rd->cpupri, p, NULL))
996                 return;
997
998         if (!cpupri_find(&rq->rd->cpupri, rq->curr, NULL))
999                 return;
1000
1001         /*
1002          * There appears to be other cpus that can accept
1003          * current and none to run 'p', so lets reschedule
1004          * to try and push current away:
1005          */
1006         requeue_task_rt(rq, p, 1);
1007         resched_task(rq->curr);
1008 }
1009
1010 #endif /* CONFIG_SMP */
1011
1012 /*
1013  * Preempt the current task with a newly woken task if needed:
1014  */
1015 static void check_preempt_curr_rt(struct rq *rq, struct task_struct *p, int flags)
1016 {
1017         if (p->prio < rq->curr->prio) {
1018                 resched_task(rq->curr);
1019                 return;
1020         }
1021
1022 #ifdef CONFIG_SMP
1023         /*
1024          * If:
1025          *
1026          * - the newly woken task is of equal priority to the current task
1027          * - the newly woken task is non-migratable while current is migratable
1028          * - current will be preempted on the next reschedule
1029          *
1030          * we should check to see if current can readily move to a different
1031          * cpu.  If so, we will reschedule to allow the push logic to try
1032          * to move current somewhere else, making room for our non-migratable
1033          * task.
1034          */
1035         if (p->prio == rq->curr->prio && !need_resched())
1036                 check_preempt_equal_prio(rq, p);
1037 #endif
1038 }
1039
1040 static struct sched_rt_entity *pick_next_rt_entity(struct rq *rq,
1041                                                    struct rt_rq *rt_rq)
1042 {
1043         struct rt_prio_array *array = &rt_rq->active;
1044         struct sched_rt_entity *next = NULL;
1045         struct list_head *queue;
1046         int idx;
1047
1048         idx = sched_find_first_bit(array->bitmap);
1049         BUG_ON(idx >= MAX_RT_PRIO);
1050
1051         queue = array->queue + idx;
1052         next = list_entry(queue->next, struct sched_rt_entity, run_list);
1053
1054         return next;
1055 }
1056
1057 static struct task_struct *_pick_next_task_rt(struct rq *rq)
1058 {
1059         struct sched_rt_entity *rt_se;
1060         struct task_struct *p;
1061         struct rt_rq *rt_rq;
1062
1063         rt_rq = &rq->rt;
1064
1065         if (unlikely(!rt_rq->rt_nr_running))
1066                 return NULL;
1067
1068         if (rt_rq_throttled(rt_rq))
1069                 return NULL;
1070
1071         do {
1072                 rt_se = pick_next_rt_entity(rq, rt_rq);
1073                 BUG_ON(!rt_se);
1074                 rt_rq = group_rt_rq(rt_se);
1075         } while (rt_rq);
1076
1077         p = rt_task_of(rt_se);
1078         p->se.exec_start = rq->clock;
1079
1080         return p;
1081 }
1082
1083 static struct task_struct *pick_next_task_rt(struct rq *rq)
1084 {
1085         struct task_struct *p = _pick_next_task_rt(rq);
1086
1087         /* The running task is never eligible for pushing */
1088         if (p)
1089                 dequeue_pushable_task(rq, p);
1090
1091 #ifdef CONFIG_SMP
1092         /*
1093          * We detect this state here so that we can avoid taking the RQ
1094          * lock again later if there is no need to push
1095          */
1096         rq->post_schedule = has_pushable_tasks(rq);
1097 #endif
1098
1099         return p;
1100 }
1101
1102 static void put_prev_task_rt(struct rq *rq, struct task_struct *p)
1103 {
1104         update_curr_rt(rq);
1105         p->se.exec_start = 0;
1106
1107         /*
1108          * The previous task needs to be made eligible for pushing
1109          * if it is still active
1110          */
1111         if (p->se.on_rq && p->rt.nr_cpus_allowed > 1)
1112                 enqueue_pushable_task(rq, p);
1113 }
1114
1115 #ifdef CONFIG_SMP
1116
1117 /* Only try algorithms three times */
1118 #define RT_MAX_TRIES 3
1119
1120 static void deactivate_task(struct rq *rq, struct task_struct *p, int sleep);
1121
1122 static int pick_rt_task(struct rq *rq, struct task_struct *p, int cpu)
1123 {
1124         if (!task_running(rq, p) &&
1125             (cpu < 0 || cpumask_test_cpu(cpu, &p->cpus_allowed)) &&
1126             (p->rt.nr_cpus_allowed > 1))
1127                 return 1;
1128         return 0;
1129 }
1130
1131 /* Return the second highest RT task, NULL otherwise */
1132 static struct task_struct *pick_next_highest_task_rt(struct rq *rq, int cpu)
1133 {
1134         struct task_struct *next = NULL;
1135         struct sched_rt_entity *rt_se;
1136         struct rt_prio_array *array;
1137         struct rt_rq *rt_rq;
1138         int idx;
1139
1140         for_each_leaf_rt_rq(rt_rq, rq) {
1141                 array = &rt_rq->active;
1142                 idx = sched_find_first_bit(array->bitmap);
1143  next_idx:
1144                 if (idx >= MAX_RT_PRIO)
1145                         continue;
1146                 if (next && next->prio < idx)
1147                         continue;
1148                 list_for_each_entry(rt_se, array->queue + idx, run_list) {
1149                         struct task_struct *p = rt_task_of(rt_se);
1150                         if (pick_rt_task(rq, p, cpu)) {
1151                                 next = p;
1152                                 break;
1153                         }
1154                 }
1155                 if (!next) {
1156                         idx = find_next_bit(array->bitmap, MAX_RT_PRIO, idx+1);
1157                         goto next_idx;
1158                 }
1159         }
1160
1161         return next;
1162 }
1163
1164 static DEFINE_PER_CPU(cpumask_var_t, local_cpu_mask);
1165
1166 static int find_lowest_rq(struct task_struct *task)
1167 {
1168         struct sched_domain *sd;
1169         struct cpumask *lowest_mask = __get_cpu_var(local_cpu_mask);
1170         int this_cpu = smp_processor_id();
1171         int cpu      = task_cpu(task);
1172
1173         if (task->rt.nr_cpus_allowed == 1)
1174                 return -1; /* No other targets possible */
1175
1176         if (!cpupri_find(&task_rq(task)->rd->cpupri, task, lowest_mask))
1177                 return -1; /* No targets found */
1178
1179         /*
1180          * At this point we have built a mask of cpus representing the
1181          * lowest priority tasks in the system.  Now we want to elect
1182          * the best one based on our affinity and topology.
1183          *
1184          * We prioritize the last cpu that the task executed on since
1185          * it is most likely cache-hot in that location.
1186          */
1187         if (cpumask_test_cpu(cpu, lowest_mask))
1188                 return cpu;
1189
1190         /*
1191          * Otherwise, we consult the sched_domains span maps to figure
1192          * out which cpu is logically closest to our hot cache data.
1193          */
1194         if (!cpumask_test_cpu(this_cpu, lowest_mask))
1195                 this_cpu = -1; /* Skip this_cpu opt if not among lowest */
1196
1197         for_each_domain(cpu, sd) {
1198                 if (sd->flags & SD_WAKE_AFFINE) {
1199                         int best_cpu;
1200
1201                         /*
1202                          * "this_cpu" is cheaper to preempt than a
1203                          * remote processor.
1204                          */
1205                         if (this_cpu != -1 &&
1206                             cpumask_test_cpu(this_cpu, sched_domain_span(sd)))
1207                                 return this_cpu;
1208
1209                         best_cpu = cpumask_first_and(lowest_mask,
1210                                                      sched_domain_span(sd));
1211                         if (best_cpu < nr_cpu_ids)
1212                                 return best_cpu;
1213                 }
1214         }
1215
1216         /*
1217          * And finally, if there were no matches within the domains
1218          * just give the caller *something* to work with from the compatible
1219          * locations.
1220          */
1221         if (this_cpu != -1)
1222                 return this_cpu;
1223
1224         cpu = cpumask_any(lowest_mask);
1225         if (cpu < nr_cpu_ids)
1226                 return cpu;
1227         return -1;
1228 }
1229
1230 /* Will lock the rq it finds */
1231 static struct rq *find_lock_lowest_rq(struct task_struct *task, struct rq *rq)
1232 {
1233         struct rq *lowest_rq = NULL;
1234         int tries;
1235         int cpu;
1236
1237         for (tries = 0; tries < RT_MAX_TRIES; tries++) {
1238                 cpu = find_lowest_rq(task);
1239
1240                 if ((cpu == -1) || (cpu == rq->cpu))
1241                         break;
1242
1243                 lowest_rq = cpu_rq(cpu);
1244
1245                 /* if the prio of this runqueue changed, try again */
1246                 if (double_lock_balance(rq, lowest_rq)) {
1247                         /*
1248                          * We had to unlock the run queue. In
1249                          * the mean time, task could have
1250                          * migrated already or had its affinity changed.
1251                          * Also make sure that it wasn't scheduled on its rq.
1252                          */
1253                         if (unlikely(task_rq(task) != rq ||
1254                                      !cpumask_test_cpu(lowest_rq->cpu,
1255                                                        &task->cpus_allowed) ||
1256                                      task_running(rq, task) ||
1257                                      !task->se.on_rq)) {
1258
1259                                 raw_spin_unlock(&lowest_rq->lock);
1260                                 lowest_rq = NULL;
1261                                 break;
1262                         }
1263                 }
1264
1265                 /* If this rq is still suitable use it. */
1266                 if (lowest_rq->rt.highest_prio.curr > task->prio)
1267                         break;
1268
1269                 /* try again */
1270                 double_unlock_balance(rq, lowest_rq);
1271                 lowest_rq = NULL;
1272         }
1273
1274         return lowest_rq;
1275 }
1276
1277 static struct task_struct *pick_next_pushable_task(struct rq *rq)
1278 {
1279         struct task_struct *p;
1280
1281         if (!has_pushable_tasks(rq))
1282                 return NULL;
1283
1284         p = plist_first_entry(&rq->rt.pushable_tasks,
1285                               struct task_struct, pushable_tasks);
1286
1287         BUG_ON(rq->cpu != task_cpu(p));
1288         BUG_ON(task_current(rq, p));
1289         BUG_ON(p->rt.nr_cpus_allowed <= 1);
1290
1291         BUG_ON(!p->se.on_rq);
1292         BUG_ON(!rt_task(p));
1293
1294         return p;
1295 }
1296
1297 /*
1298  * If the current CPU has more than one RT task, see if the non
1299  * running task can migrate over to a CPU that is running a task
1300  * of lesser priority.
1301  */
1302 static int push_rt_task(struct rq *rq)
1303 {
1304         struct task_struct *next_task;
1305         struct rq *lowest_rq;
1306
1307         if (!rq->rt.overloaded)
1308                 return 0;
1309
1310         next_task = pick_next_pushable_task(rq);
1311         if (!next_task)
1312                 return 0;
1313
1314  retry:
1315         if (unlikely(next_task == rq->curr)) {
1316                 WARN_ON(1);
1317                 return 0;
1318         }
1319
1320         /*
1321          * It's possible that the next_task slipped in of
1322          * higher priority than current. If that's the case
1323          * just reschedule current.
1324          */
1325         if (unlikely(next_task->prio < rq->curr->prio)) {
1326                 resched_task(rq->curr);
1327                 return 0;
1328         }
1329
1330         /* We might release rq lock */
1331         get_task_struct(next_task);
1332
1333         /* find_lock_lowest_rq locks the rq if found */
1334         lowest_rq = find_lock_lowest_rq(next_task, rq);
1335         if (!lowest_rq) {
1336                 struct task_struct *task;
1337                 /*
1338                  * find lock_lowest_rq releases rq->lock
1339                  * so it is possible that next_task has migrated.
1340                  *
1341                  * We need to make sure that the task is still on the same
1342                  * run-queue and is also still the next task eligible for
1343                  * pushing.
1344                  */
1345                 task = pick_next_pushable_task(rq);
1346                 if (task_cpu(next_task) == rq->cpu && task == next_task) {
1347                         /*
1348                          * If we get here, the task hasnt moved at all, but
1349                          * it has failed to push.  We will not try again,
1350                          * since the other cpus will pull from us when they
1351                          * are ready.
1352                          */
1353                         dequeue_pushable_task(rq, next_task);
1354                         goto out;
1355                 }
1356
1357                 if (!task)
1358                         /* No more tasks, just exit */
1359                         goto out;
1360
1361                 /*
1362                  * Something has shifted, try again.
1363                  */
1364                 put_task_struct(next_task);
1365                 next_task = task;
1366                 goto retry;
1367         }
1368
1369         deactivate_task(rq, next_task, 0);
1370         set_task_cpu(next_task, lowest_rq->cpu);
1371         activate_task(lowest_rq, next_task, 0);
1372
1373         resched_task(lowest_rq->curr);
1374
1375         double_unlock_balance(rq, lowest_rq);
1376
1377 out:
1378         put_task_struct(next_task);
1379
1380         return 1;
1381 }
1382
1383 static void push_rt_tasks(struct rq *rq)
1384 {
1385         /* push_rt_task will return true if it moved an RT */
1386         while (push_rt_task(rq))
1387                 ;
1388 }
1389
1390 static int pull_rt_task(struct rq *this_rq)
1391 {
1392         int this_cpu = this_rq->cpu, ret = 0, cpu;
1393         struct task_struct *p;
1394         struct rq *src_rq;
1395
1396         if (likely(!rt_overloaded(this_rq)))
1397                 return 0;
1398
1399         for_each_cpu(cpu, this_rq->rd->rto_mask) {
1400                 if (this_cpu == cpu)
1401                         continue;
1402
1403                 src_rq = cpu_rq(cpu);
1404
1405                 /*
1406                  * Don't bother taking the src_rq->lock if the next highest
1407                  * task is known to be lower-priority than our current task.
1408                  * This may look racy, but if this value is about to go
1409                  * logically higher, the src_rq will push this task away.
1410                  * And if its going logically lower, we do not care
1411                  */
1412                 if (src_rq->rt.highest_prio.next >=
1413                     this_rq->rt.highest_prio.curr)
1414                         continue;
1415
1416                 /*
1417                  * We can potentially drop this_rq's lock in
1418                  * double_lock_balance, and another CPU could
1419                  * alter this_rq
1420                  */
1421                 double_lock_balance(this_rq, src_rq);
1422
1423                 /*
1424                  * Are there still pullable RT tasks?
1425                  */
1426                 if (src_rq->rt.rt_nr_running <= 1)
1427                         goto skip;
1428
1429                 p = pick_next_highest_task_rt(src_rq, this_cpu);
1430
1431                 /*
1432                  * Do we have an RT task that preempts
1433                  * the to-be-scheduled task?
1434                  */
1435                 if (p && (p->prio < this_rq->rt.highest_prio.curr)) {
1436                         WARN_ON(p == src_rq->curr);
1437                         WARN_ON(!p->se.on_rq);
1438
1439                         /*
1440                          * There's a chance that p is higher in priority
1441                          * than what's currently running on its cpu.
1442                          * This is just that p is wakeing up and hasn't
1443                          * had a chance to schedule. We only pull
1444                          * p if it is lower in priority than the
1445                          * current task on the run queue
1446                          */
1447                         if (p->prio < src_rq->curr->prio)
1448                                 goto skip;
1449
1450                         ret = 1;
1451
1452                         deactivate_task(src_rq, p, 0);
1453                         set_task_cpu(p, this_cpu);
1454                         activate_task(this_rq, p, 0);
1455                         /*
1456                          * We continue with the search, just in
1457                          * case there's an even higher prio task
1458                          * in another runqueue. (low likelyhood
1459                          * but possible)
1460                          */
1461                 }
1462  skip:
1463                 double_unlock_balance(this_rq, src_rq);
1464         }
1465
1466         return ret;
1467 }
1468
1469 static void pre_schedule_rt(struct rq *rq, struct task_struct *prev)
1470 {
1471         /* Try to pull RT tasks here if we lower this rq's prio */
1472         if (unlikely(rt_task(prev)) && rq->rt.highest_prio.curr > prev->prio)
1473                 pull_rt_task(rq);
1474 }
1475
1476 static void post_schedule_rt(struct rq *rq)
1477 {
1478         push_rt_tasks(rq);
1479 }
1480
1481 /*
1482  * If we are not running and we are not going to reschedule soon, we should
1483  * try to push tasks away now
1484  */
1485 static void task_woken_rt(struct rq *rq, struct task_struct *p)
1486 {
1487         if (!task_running(rq, p) &&
1488             !test_tsk_need_resched(rq->curr) &&
1489             has_pushable_tasks(rq) &&
1490             p->rt.nr_cpus_allowed > 1)
1491                 push_rt_tasks(rq);
1492 }
1493
1494 static void set_cpus_allowed_rt(struct task_struct *p,
1495                                 const struct cpumask *new_mask)
1496 {
1497         int weight = cpumask_weight(new_mask);
1498
1499         BUG_ON(!rt_task(p));
1500
1501         /*
1502          * Update the migration status of the RQ if we have an RT task
1503          * which is running AND changing its weight value.
1504          */
1505         if (p->se.on_rq && (weight != p->rt.nr_cpus_allowed)) {
1506                 struct rq *rq = task_rq(p);
1507
1508                 if (!task_current(rq, p)) {
1509                         /*
1510                          * Make sure we dequeue this task from the pushable list
1511                          * before going further.  It will either remain off of
1512                          * the list because we are no longer pushable, or it
1513                          * will be requeued.
1514                          */
1515                         if (p->rt.nr_cpus_allowed > 1)
1516                                 dequeue_pushable_task(rq, p);
1517
1518                         /*
1519                          * Requeue if our weight is changing and still > 1
1520                          */
1521                         if (weight > 1)
1522                                 enqueue_pushable_task(rq, p);
1523
1524                 }
1525
1526                 if ((p->rt.nr_cpus_allowed <= 1) && (weight > 1)) {
1527                         rq->rt.rt_nr_migratory++;
1528                 } else if ((p->rt.nr_cpus_allowed > 1) && (weight <= 1)) {
1529                         BUG_ON(!rq->rt.rt_nr_migratory);
1530                         rq->rt.rt_nr_migratory--;
1531                 }
1532
1533                 update_rt_migration(&rq->rt);
1534         }
1535
1536         cpumask_copy(&p->cpus_allowed, new_mask);
1537         p->rt.nr_cpus_allowed = weight;
1538 }
1539
1540 /* Assumes rq->lock is held */
1541 static void rq_online_rt(struct rq *rq)
1542 {
1543         if (rq->rt.overloaded)
1544                 rt_set_overload(rq);
1545
1546         __enable_runtime(rq);
1547
1548         cpupri_set(&rq->rd->cpupri, rq->cpu, rq->rt.highest_prio.curr);
1549 }
1550
1551 /* Assumes rq->lock is held */
1552 static void rq_offline_rt(struct rq *rq)
1553 {
1554         if (rq->rt.overloaded)
1555                 rt_clear_overload(rq);
1556
1557         __disable_runtime(rq);
1558
1559         cpupri_set(&rq->rd->cpupri, rq->cpu, CPUPRI_INVALID);
1560 }
1561
1562 /*
1563  * When switch from the rt queue, we bring ourselves to a position
1564  * that we might want to pull RT tasks from other runqueues.
1565  */
1566 static void switched_from_rt(struct rq *rq, struct task_struct *p,
1567                            int running)
1568 {
1569         /*
1570          * If there are other RT tasks then we will reschedule
1571          * and the scheduling of the other RT tasks will handle
1572          * the balancing. But if we are the last RT task
1573          * we may need to handle the pulling of RT tasks
1574          * now.
1575          */
1576         if (!rq->rt.rt_nr_running)
1577                 pull_rt_task(rq);
1578 }
1579
1580 static inline void init_sched_rt_class(void)
1581 {
1582         unsigned int i;
1583
1584         for_each_possible_cpu(i)
1585                 zalloc_cpumask_var_node(&per_cpu(local_cpu_mask, i),
1586                                         GFP_KERNEL, cpu_to_node(i));
1587 }
1588 #endif /* CONFIG_SMP */
1589
1590 /*
1591  * When switching a task to RT, we may overload the runqueue
1592  * with RT tasks. In this case we try to push them off to
1593  * other runqueues.
1594  */
1595 static void switched_to_rt(struct rq *rq, struct task_struct *p,
1596                            int running)
1597 {
1598         int check_resched = 1;
1599
1600         /*
1601          * If we are already running, then there's nothing
1602          * that needs to be done. But if we are not running
1603          * we may need to preempt the current running task.
1604          * If that current running task is also an RT task
1605          * then see if we can move to another run queue.
1606          */
1607         if (!running) {
1608 #ifdef CONFIG_SMP
1609                 if (rq->rt.overloaded && push_rt_task(rq) &&
1610                     /* Don't resched if we changed runqueues */
1611                     rq != task_rq(p))
1612                         check_resched = 0;
1613 #endif /* CONFIG_SMP */
1614                 if (check_resched && p->prio < rq->curr->prio)
1615                         resched_task(rq->curr);
1616         }
1617 }
1618
1619 /*
1620  * Priority of the task has changed. This may cause
1621  * us to initiate a push or pull.
1622  */
1623 static void prio_changed_rt(struct rq *rq, struct task_struct *p,
1624                             int oldprio, int running)
1625 {
1626         if (running) {
1627 #ifdef CONFIG_SMP
1628                 /*
1629                  * If our priority decreases while running, we
1630                  * may need to pull tasks to this runqueue.
1631                  */
1632                 if (oldprio < p->prio)
1633                         pull_rt_task(rq);
1634                 /*
1635                  * If there's a higher priority task waiting to run
1636                  * then reschedule. Note, the above pull_rt_task
1637                  * can release the rq lock and p could migrate.
1638                  * Only reschedule if p is still on the same runqueue.
1639                  */
1640                 if (p->prio > rq->rt.highest_prio.curr && rq->curr == p)
1641                         resched_task(p);
1642 #else
1643                 /* For UP simply resched on drop of prio */
1644                 if (oldprio < p->prio)
1645                         resched_task(p);
1646 #endif /* CONFIG_SMP */
1647         } else {
1648                 /*
1649                  * This task is not running, but if it is
1650                  * greater than the current running task
1651                  * then reschedule.
1652                  */
1653                 if (p->prio < rq->curr->prio)
1654                         resched_task(rq->curr);
1655         }
1656 }
1657
1658 static void watchdog(struct rq *rq, struct task_struct *p)
1659 {
1660         unsigned long soft, hard;
1661
1662         if (!p->signal)
1663                 return;
1664
1665         /* max may change after cur was read, this will be fixed next tick */
1666         soft = task_rlimit(p, RLIMIT_RTTIME);
1667         hard = task_rlimit_max(p, RLIMIT_RTTIME);
1668
1669         if (soft != RLIM_INFINITY) {
1670                 unsigned long next;
1671
1672                 p->rt.timeout++;
1673                 next = DIV_ROUND_UP(min(soft, hard), USEC_PER_SEC/HZ);
1674                 if (p->rt.timeout > next)
1675                         p->cputime_expires.sched_exp = p->se.sum_exec_runtime;
1676         }
1677 }
1678
1679 static void task_tick_rt(struct rq *rq, struct task_struct *p, int queued)
1680 {
1681         update_curr_rt(rq);
1682
1683         watchdog(rq, p);
1684
1685         /*
1686          * RR tasks need a special form of timeslice management.
1687          * FIFO tasks have no timeslices.
1688          */
1689         if (p->policy != SCHED_RR)
1690                 return;
1691
1692         if (--p->rt.time_slice)
1693                 return;
1694
1695         p->rt.time_slice = DEF_TIMESLICE;
1696
1697         /*
1698          * Requeue to the end of queue if we are not the only element
1699          * on the queue:
1700          */
1701         if (p->rt.run_list.prev != p->rt.run_list.next) {
1702                 requeue_task_rt(rq, p, 0);
1703                 set_tsk_need_resched(p);
1704         }
1705 }
1706
1707 static void set_curr_task_rt(struct rq *rq)
1708 {
1709         struct task_struct *p = rq->curr;
1710
1711         p->se.exec_start = rq->clock;
1712
1713         /* The running task is never eligible for pushing */
1714         dequeue_pushable_task(rq, p);
1715 }
1716
1717 static unsigned int get_rr_interval_rt(struct rq *rq, struct task_struct *task)
1718 {
1719         /*
1720          * Time slice is 0 for SCHED_FIFO tasks
1721          */
1722         if (task->policy == SCHED_RR)
1723                 return DEF_TIMESLICE;
1724         else
1725                 return 0;
1726 }
1727
1728 static const struct sched_class rt_sched_class = {
1729         .next                   = &fair_sched_class,
1730         .enqueue_task           = enqueue_task_rt,
1731         .dequeue_task           = dequeue_task_rt,
1732         .yield_task             = yield_task_rt,
1733
1734         .check_preempt_curr     = check_preempt_curr_rt,
1735
1736         .pick_next_task         = pick_next_task_rt,
1737         .put_prev_task          = put_prev_task_rt,
1738
1739 #ifdef CONFIG_SMP
1740         .select_task_rq         = select_task_rq_rt,
1741
1742         .set_cpus_allowed       = set_cpus_allowed_rt,
1743         .rq_online              = rq_online_rt,
1744         .rq_offline             = rq_offline_rt,
1745         .pre_schedule           = pre_schedule_rt,
1746         .post_schedule          = post_schedule_rt,
1747         .task_woken             = task_woken_rt,
1748         .switched_from          = switched_from_rt,
1749 #endif
1750
1751         .set_curr_task          = set_curr_task_rt,
1752         .task_tick              = task_tick_rt,
1753
1754         .get_rr_interval        = get_rr_interval_rt,
1755
1756         .prio_changed           = prio_changed_rt,
1757         .switched_to            = switched_to_rt,
1758 };
1759
1760 #ifdef CONFIG_SCHED_DEBUG
1761 extern void print_rt_rq(struct seq_file *m, int cpu, struct rt_rq *rt_rq);
1762
1763 static void print_rt_stats(struct seq_file *m, int cpu)
1764 {
1765         struct rt_rq *rt_rq;
1766
1767         rcu_read_lock();
1768         for_each_leaf_rt_rq(rt_rq, cpu_rq(cpu))
1769                 print_rt_rq(m, cpu, rt_rq);
1770         rcu_read_unlock();
1771 }
1772 #endif /* CONFIG_SCHED_DEBUG */
1773