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 typedef struct task_group *rt_rq_iter_t;
 187
 188 #define for_each_rt_rq(rt_rq, iter, rq) \
 189         for (iter = list_entry_rcu(task_groups.next, typeof(*iter), list); \
 190              (&iter->list != &task_groups) && \
 191              (rt_rq = iter->rt_rq[cpu_of(rq)]); \
 192              iter = list_entry_rcu(iter->list.next, typeof(*iter), list))
 193
 194 static inline void list_add_leaf_rt_rq(struct rt_rq *rt_rq)
 195 {
 196         list_add_rcu(&rt_rq->leaf_rt_rq_list,
 197                         &rq_of_rt_rq(rt_rq)->leaf_rt_rq_list);
 198 }
 199
 200 static inline void list_del_leaf_rt_rq(struct rt_rq *rt_rq)
 201 {
 202         list_del_rcu(&rt_rq->leaf_rt_rq_list);
 203 }
 204
 205 #define for_each_leaf_rt_rq(rt_rq, rq) \
 206         list_for_each_entry_rcu(rt_rq, &rq->leaf_rt_rq_list, leaf_rt_rq_list)
 207
 208 #define for_each_sched_rt_entity(rt_se) \
 209         for (; rt_se; rt_se = rt_se->parent)
 210
 211 static inline struct rt_rq *group_rt_rq(struct sched_rt_entity *rt_se)
 212 {
 213         return rt_se->my_q;
 214 }
 215
 216 static void enqueue_rt_entity(struct sched_rt_entity *rt_se, bool head);
 217 static void dequeue_rt_entity(struct sched_rt_entity *rt_se);
 218
 219 static void sched_rt_rq_enqueue(struct rt_rq *rt_rq)
 220 {
 221         struct task_struct *curr = rq_of_rt_rq(rt_rq)->curr;
 222         struct sched_rt_entity *rt_se;
 223
 224         int cpu = cpu_of(rq_of_rt_rq(rt_rq));
 225
 226         rt_se = rt_rq->tg->rt_se[cpu];
 227
 228         if (rt_rq->rt_nr_running) {
 229                 if (rt_se && !on_rt_rq(rt_se))
 230                         enqueue_rt_entity(rt_se, false);
 231                 if (rt_rq->highest_prio.curr < curr->prio)
 232                         resched_task(curr);
 233         }
 234 }
 235
 236 static void sched_rt_rq_dequeue(struct rt_rq *rt_rq)
 237 {
 238         struct sched_rt_entity *rt_se;
 239         int cpu = cpu_of(rq_of_rt_rq(rt_rq));
 240
 241         rt_se = rt_rq->tg->rt_se[cpu];
 242
 243         if (rt_se && on_rt_rq(rt_se))
 244                 dequeue_rt_entity(rt_se);
 245 }
 246
 247 static inline int rt_rq_throttled(struct rt_rq *rt_rq)
 248 {
 249         return rt_rq->rt_throttled && !rt_rq->rt_nr_boosted;
 250 }
 251
 252 static int rt_se_boosted(struct sched_rt_entity *rt_se)
 253 {
 254         struct rt_rq *rt_rq = group_rt_rq(rt_se);
 255         struct task_struct *p;
 256
 257         if (rt_rq)
 258                 return !!rt_rq->rt_nr_boosted;
 259
 260         p = rt_task_of(rt_se);
 261         return p->prio != p->normal_prio;
 262 }
 263
 264 #ifdef CONFIG_SMP
 265 static inline const struct cpumask *sched_rt_period_mask(void)
 266 {
 267         return cpu_rq(smp_processor_id())->rd->span;
 268 }
 269 #else
 270 static inline const struct cpumask *sched_rt_period_mask(void)
 271 {
 272         return cpu_online_mask;
 273 }
 274 #endif
 275
 276 static inline
 277 struct rt_rq *sched_rt_period_rt_rq(struct rt_bandwidth *rt_b, int cpu)
 278 {
 279         return container_of(rt_b, struct task_group, rt_bandwidth)->rt_rq[cpu];
 280 }
 281
 282 static inline struct rt_bandwidth *sched_rt_bandwidth(struct rt_rq *rt_rq)
 283 {
 284         return &rt_rq->tg->rt_bandwidth;
 285 }
 286
 287 #else /* !CONFIG_RT_GROUP_SCHED */
 288
 289 static inline u64 sched_rt_runtime(struct rt_rq *rt_rq)
 290 {
 291         return rt_rq->rt_runtime;
 292 }
 293
 294 static inline u64 sched_rt_period(struct rt_rq *rt_rq)
 295 {
 296         return ktime_to_ns(def_rt_bandwidth.rt_period);
 297 }
 298
 299 typedef struct rt_rq *rt_rq_iter_t;
 300
 301 #define for_each_rt_rq(rt_rq, iter, rq) \
 302         for ((void) iter, rt_rq = &rq->rt; rt_rq; rt_rq = NULL)
 303
 304 static inline void list_add_leaf_rt_rq(struct rt_rq *rt_rq)
 305 {
 306 }
 307
 308 static inline void list_del_leaf_rt_rq(struct rt_rq *rt_rq)
 309 {
 310 }
 311
 312 #define for_each_leaf_rt_rq(rt_rq, rq) \
 313         for (rt_rq = &rq->rt; rt_rq; rt_rq = NULL)
 314
 315 #define for_each_sched_rt_entity(rt_se) \
 316         for (; rt_se; rt_se = NULL)
 317
 318 static inline struct rt_rq *group_rt_rq(struct sched_rt_entity *rt_se)
 319 {
 320         return NULL;
 321 }
 322
 323 static inline void sched_rt_rq_enqueue(struct rt_rq *rt_rq)
 324 {
 325         if (rt_rq->rt_nr_running)
 326                 resched_task(rq_of_rt_rq(rt_rq)->curr);
 327 }
 328
 329 static inline void sched_rt_rq_dequeue(struct rt_rq *rt_rq)
 330 {
 331 }
 332
 333 static inline int rt_rq_throttled(struct rt_rq *rt_rq)
 334 {
 335         return rt_rq->rt_throttled;
 336 }
 337
 338 static inline const struct cpumask *sched_rt_period_mask(void)
 339 {
 340         return cpu_online_mask;
 341 }
 342
 343 static inline
 344 struct rt_rq *sched_rt_period_rt_rq(struct rt_bandwidth *rt_b, int cpu)
 345 {
 346         return &cpu_rq(cpu)->rt;
 347 }
 348
 349 static inline struct rt_bandwidth *sched_rt_bandwidth(struct rt_rq *rt_rq)
 350 {
 351         return &def_rt_bandwidth;
 352 }
 353
 354 #endif /* CONFIG_RT_GROUP_SCHED */
 355
 356 #ifdef CONFIG_SMP
 357 /*
 358  * We ran out of runtime, see if we can borrow some from our neighbours.
 359  */
 360 static int do_balance_runtime(struct rt_rq *rt_rq)
 361 {
 362         struct rt_bandwidth *rt_b = sched_rt_bandwidth(rt_rq);
 363         struct root_domain *rd = cpu_rq(smp_processor_id())->rd;
 364         int i, weight, more = 0;
 365         u64 rt_period;
 366
 367         weight = cpumask_weight(rd->span);
 368
 369         raw_spin_lock(&rt_b->rt_runtime_lock);
 370         rt_period = ktime_to_ns(rt_b->rt_period);
 371         for_each_cpu(i, rd->span) {
 372                 struct rt_rq *iter = sched_rt_period_rt_rq(rt_b, i);
 373                 s64 diff;
 374
 375                 if (iter == rt_rq)
 376                         continue;
 377
 378                 raw_spin_lock(&iter->rt_runtime_lock);
 379                 /*
 380                  * Either all rqs have inf runtime and there's nothing to steal
 381                  * or __disable_runtime() below sets a specific rq to inf to
 382                  * indicate its been disabled and disalow stealing.
 383                  */
 384                 if (iter->rt_runtime == RUNTIME_INF)
 385                         goto next;
 386
 387                 /*
 388                  * From runqueues with spare time, take 1/n part of their
 389                  * spare time, but no more than our period.
 390                  */
 391                 diff = iter->rt_runtime - iter->rt_time;
 392                 if (diff > 0) {
 393                         diff = div_u64((u64)diff, weight);
 394                         if (rt_rq->rt_runtime + diff > rt_period)
 395                                 diff = rt_period - rt_rq->rt_runtime;
 396                         iter->rt_runtime -= diff;
 397                         rt_rq->rt_runtime += diff;
 398                         more = 1;
 399                         if (rt_rq->rt_runtime == rt_period) {
 400                                 raw_spin_unlock(&iter->rt_runtime_lock);
 401                                 break;
 402                         }
 403                 }
 404 next:
 405                 raw_spin_unlock(&iter->rt_runtime_lock);
 406         }
 407         raw_spin_unlock(&rt_b->rt_runtime_lock);
 408
 409         return more;
 410 }
 411
 412 /*
 413  * Ensure this RQ takes back all the runtime it lend to its neighbours.
 414  */
 415 static void __disable_runtime(struct rq *rq)
 416 {
 417         struct root_domain *rd = rq->rd;
 418         rt_rq_iter_t iter;
 419         struct rt_rq *rt_rq;
 420
 421         if (unlikely(!scheduler_running))
 422                 return;
 423
 424         for_each_rt_rq(rt_rq, iter, rq) {
 425                 struct rt_bandwidth *rt_b = sched_rt_bandwidth(rt_rq);
 426                 s64 want;
 427                 int i;
 428
 429                 raw_spin_lock(&rt_b->rt_runtime_lock);
 430                 raw_spin_lock(&rt_rq->rt_runtime_lock);
 431                 /*
 432                  * Either we're all inf and nobody needs to borrow, or we're
 433                  * already disabled and thus have nothing to do, or we have
 434                  * exactly the right amount of runtime to take out.
 435                  */
 436                 if (rt_rq->rt_runtime == RUNTIME_INF ||
 437                                 rt_rq->rt_runtime == rt_b->rt_runtime)
 438                         goto balanced;
 439                 raw_spin_unlock(&rt_rq->rt_runtime_lock);
 440
 441                 /*
 442                  * Calculate the difference between what we started out with
 443                  * and what we current have, that's the amount of runtime
 444                  * we lend and now have to reclaim.
 445                  */
 446                 want = rt_b->rt_runtime - rt_rq->rt_runtime;
 447
 448                 /*
 449                  * Greedy reclaim, take back as much as we can.
 450                  */
 451                 for_each_cpu(i, rd->span) {
 452                         struct rt_rq *iter = sched_rt_period_rt_rq(rt_b, i);
 453                         s64 diff;
 454
 455                         /*
 456                          * Can't reclaim from ourselves or disabled runqueues.
 457                          */
 458                         if (iter == rt_rq || iter->rt_runtime == RUNTIME_INF)
 459                                 continue;
 460
 461                         raw_spin_lock(&iter->rt_runtime_lock);
 462                         if (want > 0) {
 463                                 diff = min_t(s64, iter->rt_runtime, want);
 464                                 iter->rt_runtime -= diff;
 465                                 want -= diff;
 466                         } else {
 467                                 iter->rt_runtime -= want;
 468                                 want -= want;
 469                         }
 470                         raw_spin_unlock(&iter->rt_runtime_lock);
 471
 472                         if (!want)
 473                                 break;
 474                 }
 475
 476                 raw_spin_lock(&rt_rq->rt_runtime_lock);
 477                 /*
 478                  * We cannot be left wanting - that would mean some runtime
 479                  * leaked out of the system.
 480                  */
 481                 BUG_ON(want);
 482 balanced:
 483                 /*
 484                  * Disable all the borrow logic by pretending we have inf
 485                  * runtime - in which case borrowing doesn't make sense.
 486                  */
 487                 rt_rq->rt_runtime = RUNTIME_INF;
 488                 raw_spin_unlock(&rt_rq->rt_runtime_lock);
 489                 raw_spin_unlock(&rt_b->rt_runtime_lock);
 490         }
 491 }
 492
 493 static void disable_runtime(struct rq *rq)
 494 {
 495         unsigned long flags;
 496
 497         raw_spin_lock_irqsave(&rq->lock, flags);
 498         __disable_runtime(rq);
 499         raw_spin_unlock_irqrestore(&rq->lock, flags);
 500 }
 501
 502 static void __enable_runtime(struct rq *rq)
 503 {
 504         rt_rq_iter_t iter;
 505         struct rt_rq *rt_rq;
 506
 507         if (unlikely(!scheduler_running))
 508                 return;
 509
 510         /*
 511          * Reset each runqueue's bandwidth settings
 512          */
 513         for_each_rt_rq(rt_rq, iter, rq) {
 514                 struct rt_bandwidth *rt_b = sched_rt_bandwidth(rt_rq);
 515
 516                 raw_spin_lock(&rt_b->rt_runtime_lock);
 517                 raw_spin_lock(&rt_rq->rt_runtime_lock);
 518                 rt_rq->rt_runtime = rt_b->rt_runtime;
 519                 rt_rq->rt_time = 0;
 520                 rt_rq->rt_throttled = 0;
 521                 raw_spin_unlock(&rt_rq->rt_runtime_lock);
 522                 raw_spin_unlock(&rt_b->rt_runtime_lock);
 523         }
 524 }
 525
 526 static void enable_runtime(struct rq *rq)
 527 {
 528         unsigned long flags;
 529
 530         raw_spin_lock_irqsave(&rq->lock, flags);
 531         __enable_runtime(rq);
 532         raw_spin_unlock_irqrestore(&rq->lock, flags);
 533 }
 534
 535 static int balance_runtime(struct rt_rq *rt_rq)
 536 {
 537         int more = 0;
 538
 539         if (rt_rq->rt_time > rt_rq->rt_runtime) {
 540                 raw_spin_unlock(&rt_rq->rt_runtime_lock);
 541                 more = do_balance_runtime(rt_rq);
 542                 raw_spin_lock(&rt_rq->rt_runtime_lock);
 543         }
 544
 545         return more;
 546 }
 547 #else /* !CONFIG_SMP */
 548 static inline int balance_runtime(struct rt_rq *rt_rq)
 549 {
 550         return 0;
 551 }
 552 #endif /* CONFIG_SMP */
 553
 554 static int do_sched_rt_period_timer(struct rt_bandwidth *rt_b, int overrun)
 555 {
 556         int i, idle = 1;
 557         const struct cpumask *span;
 558
 559         if (!rt_bandwidth_enabled() || rt_b->rt_runtime == RUNTIME_INF)
 560                 return 1;
 561
 562         span = sched_rt_period_mask();
 563         for_each_cpu(i, span) {
 564                 int enqueue = 0;
 565                 struct rt_rq *rt_rq = sched_rt_period_rt_rq(rt_b, i);
 566                 struct rq *rq = rq_of_rt_rq(rt_rq);
 567
 568                 raw_spin_lock(&rq->lock);
 569                 if (rt_rq->rt_time) {
 570                         u64 runtime;
 571
 572                         raw_spin_lock(&rt_rq->rt_runtime_lock);
 573                         if (rt_rq->rt_throttled)
 574                                 balance_runtime(rt_rq);
 575                         runtime = rt_rq->rt_runtime;
 576                         rt_rq->rt_time -= min(rt_rq->rt_time, overrun*runtime);
 577                         if (rt_rq->rt_throttled && rt_rq->rt_time < runtime) {
 578                                 rt_rq->rt_throttled = 0;
 579                                 enqueue = 1;
 580                         }
 581                         if (rt_rq->rt_time || rt_rq->rt_nr_running)
 582                                 idle = 0;
 583                         raw_spin_unlock(&rt_rq->rt_runtime_lock);
 584                 } else if (rt_rq->rt_nr_running) {
 585                         idle = 0;
 586                         if (!rt_rq_throttled(rt_rq))
 587                                 enqueue = 1;
 588                 }
 589
 590                 if (enqueue)
 591                         sched_rt_rq_enqueue(rt_rq);
 592                 raw_spin_unlock(&rq->lock);
 593         }
 594
 595         return idle;
 596 }
 597
 598 static inline int rt_se_prio(struct sched_rt_entity *rt_se)
 599 {
 600 #ifdef CONFIG_RT_GROUP_SCHED
 601         struct rt_rq *rt_rq = group_rt_rq(rt_se);
 602
 603         if (rt_rq)
 604                 return rt_rq->highest_prio.curr;
 605 #endif
 606
 607         return rt_task_of(rt_se)->prio;
 608 }
 609
 610 static int sched_rt_runtime_exceeded(struct rt_rq *rt_rq)
 611 {
 612         u64 runtime = sched_rt_runtime(rt_rq);
 613
 614         if (rt_rq->rt_throttled)
 615                 return rt_rq_throttled(rt_rq);
 616
 617         if (sched_rt_runtime(rt_rq) >= sched_rt_period(rt_rq))
 618                 return 0;
 619
 620         balance_runtime(rt_rq);
 621         runtime = sched_rt_runtime(rt_rq);
 622         if (runtime == RUNTIME_INF)
 623                 return 0;
 624
 625         if (rt_rq->rt_time > runtime) {
 626                 rt_rq->rt_throttled = 1;
 627                 if (rt_rq_throttled(rt_rq)) {
 628                         sched_rt_rq_dequeue(rt_rq);
 629                         return 1;
 630                 }
 631         }
 632
 633         return 0;
 634 }
 635
 636 /*
 637  * Update the current task's runtime statistics. Skip current tasks that
 638  * are not in our scheduling class.
 639  */
 640 static void update_curr_rt(struct rq *rq)
 641 {
 642         struct task_struct *curr = rq->curr;
 643         struct sched_rt_entity *rt_se = &curr->rt;
 644         struct rt_rq *rt_rq = rt_rq_of_se(rt_se);
 645         u64 delta_exec;
 646
 647         if (curr->sched_class != &rt_sched_class)
 648                 return;
 649
 650         delta_exec = rq->clock_task - curr->se.exec_start;
 651         if (unlikely((s64)delta_exec < 0))
 652                 delta_exec = 0;
 653
 654         schedstat_set(curr->se.statistics.exec_max, max(curr->se.statistics.exec_max, delta_exec));
 655
 656         curr->se.sum_exec_runtime += delta_exec;
 657         account_group_exec_runtime(curr, delta_exec);
 658
 659         curr->se.exec_start = rq->clock_task;
 660         cpuacct_charge(curr, delta_exec);
 661
 662         sched_rt_avg_update(rq, delta_exec);
 663
 664         if (!rt_bandwidth_enabled())
 665                 return;
 666
 667         for_each_sched_rt_entity(rt_se) {
 668                 rt_rq = rt_rq_of_se(rt_se);
 669
 670                 if (sched_rt_runtime(rt_rq) != RUNTIME_INF) {
 671                         raw_spin_lock(&rt_rq->rt_runtime_lock);
 672                         rt_rq->rt_time += delta_exec;
 673                         if (sched_rt_runtime_exceeded(rt_rq))
 674                                 resched_task(curr);
 675                         raw_spin_unlock(&rt_rq->rt_runtime_lock);
 676                 }
 677         }
 678 }
 679
 680 #if defined CONFIG_SMP
 681
 682 static struct task_struct *pick_next_highest_task_rt(struct rq *rq, int cpu);
 683
 684 static inline int next_prio(struct rq *rq)
 685 {
 686         struct task_struct *next = pick_next_highest_task_rt(rq, rq->cpu);
 687
 688         if (next && rt_prio(next->prio))
 689                 return next->prio;
 690         else
 691                 return MAX_RT_PRIO;
 692 }
 693
 694 static void
 695 inc_rt_prio_smp(struct rt_rq *rt_rq, int prio, int prev_prio)
 696 {
 697         struct rq *rq = rq_of_rt_rq(rt_rq);
 698
 699         if (prio < prev_prio) {
 700
 701                 /*
 702                  * If the new task is higher in priority than anything on the
 703                  * run-queue, we know that the previous high becomes our
 704                  * next-highest.
 705                  */
 706                 rt_rq->highest_prio.next = prev_prio;
 707
 708                 if (rq->online)
 709                         cpupri_set(&rq->rd->cpupri, rq->cpu, prio);
 710
 711         } else if (prio == rt_rq->highest_prio.curr)
 712                 /*
 713                  * If the next task is equal in priority to the highest on
 714                  * the run-queue, then we implicitly know that the next highest
 715                  * task cannot be any lower than current
 716                  */
 717                 rt_rq->highest_prio.next = prio;
 718         else if (prio < rt_rq->highest_prio.next)
 719                 /*
 720                  * Otherwise, we need to recompute next-highest
 721                  */
 722                 rt_rq->highest_prio.next = next_prio(rq);
 723 }
 724
 725 static void
 726 dec_rt_prio_smp(struct rt_rq *rt_rq, int prio, int prev_prio)
 727 {
 728         struct rq *rq = rq_of_rt_rq(rt_rq);
 729
 730         if (rt_rq->rt_nr_running && (prio <= rt_rq->highest_prio.next))
 731                 rt_rq->highest_prio.next = next_prio(rq);
 732
 733         if (rq->online && rt_rq->highest_prio.curr != prev_prio)
 734                 cpupri_set(&rq->rd->cpupri, rq->cpu, rt_rq->highest_prio.curr);
 735 }
 736
 737 #else /* CONFIG_SMP */
 738
 739 static inline
 740 void inc_rt_prio_smp(struct rt_rq *rt_rq, int prio, int prev_prio) {}
 741 static inline
 742 void dec_rt_prio_smp(struct rt_rq *rt_rq, int prio, int prev_prio) {}
 743
 744 #endif /* CONFIG_SMP */
 745
 746 #if defined CONFIG_SMP || defined CONFIG_RT_GROUP_SCHED
 747 static void
 748 inc_rt_prio(struct rt_rq *rt_rq, int prio)
 749 {
 750         int prev_prio = rt_rq->highest_prio.curr;
 751
 752         if (prio < prev_prio)
 753                 rt_rq->highest_prio.curr = prio;
 754
 755         inc_rt_prio_smp(rt_rq, prio, prev_prio);
 756 }
 757
 758 static void
 759 dec_rt_prio(struct rt_rq *rt_rq, int prio)
 760 {
 761         int prev_prio = rt_rq->highest_prio.curr;
 762
 763         if (rt_rq->rt_nr_running) {
 764
 765                 WARN_ON(prio < prev_prio);
 766
 767                 /*
 768                  * This may have been our highest task, and therefore
 769                  * we may have some recomputation to do
 770                  */
 771                 if (prio == prev_prio) {
 772                         struct rt_prio_array *array = &rt_rq->active;
 773
 774                         rt_rq->highest_prio.curr =
 775                                 sched_find_first_bit(array->bitmap);
 776                 }
 777
 778         } else
 779                 rt_rq->highest_prio.curr = MAX_RT_PRIO;
 780
 781         dec_rt_prio_smp(rt_rq, prio, prev_prio);
 782 }
 783
 784 #else
 785
 786 static inline void inc_rt_prio(struct rt_rq *rt_rq, int prio) {}
 787 static inline void dec_rt_prio(struct rt_rq *rt_rq, int prio) {}
 788
 789 #endif /* CONFIG_SMP || CONFIG_RT_GROUP_SCHED */
 790
 791 #ifdef CONFIG_RT_GROUP_SCHED
 792
 793 static void
 794 inc_rt_group(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
 795 {
 796         if (rt_se_boosted(rt_se))
 797                 rt_rq->rt_nr_boosted++;
 798
 799         if (rt_rq->tg)
 800                 start_rt_bandwidth(&rt_rq->tg->rt_bandwidth);
 801 }
 802
 803 static void
 804 dec_rt_group(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
 805 {
 806         if (rt_se_boosted(rt_se))
 807                 rt_rq->rt_nr_boosted--;
 808
 809         WARN_ON(!rt_rq->rt_nr_running && rt_rq->rt_nr_boosted);
 810 }
 811
 812 #else /* CONFIG_RT_GROUP_SCHED */
 813
 814 static void
 815 inc_rt_group(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
 816 {
 817         start_rt_bandwidth(&def_rt_bandwidth);
 818 }
 819
 820 static inline
 821 void dec_rt_group(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq) {}
 822
 823 #endif /* CONFIG_RT_GROUP_SCHED */
 824
 825 static inline
 826 void inc_rt_tasks(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
 827 {
 828         int prio = rt_se_prio(rt_se);
 829
 830         WARN_ON(!rt_prio(prio));
 831         rt_rq->rt_nr_running++;
 832
 833         inc_rt_prio(rt_rq, prio);
 834         inc_rt_migration(rt_se, rt_rq);
 835         inc_rt_group(rt_se, rt_rq);
 836 }
 837
 838 static inline
 839 void dec_rt_tasks(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
 840 {
 841         WARN_ON(!rt_prio(rt_se_prio(rt_se)));
 842         WARN_ON(!rt_rq->rt_nr_running);
 843         rt_rq->rt_nr_running--;
 844
 845         dec_rt_prio(rt_rq, rt_se_prio(rt_se));
 846         dec_rt_migration(rt_se, rt_rq);
 847         dec_rt_group(rt_se, rt_rq);
 848 }
 849
 850 static void __enqueue_rt_entity(struct sched_rt_entity *rt_se, bool head)
 851 {
 852         struct rt_rq *rt_rq = rt_rq_of_se(rt_se);
 853         struct rt_prio_array *array = &rt_rq->active;
 854         struct rt_rq *group_rq = group_rt_rq(rt_se);
 855         struct list_head *queue = array->queue + rt_se_prio(rt_se);
 856
 857         /*
 858          * Don't enqueue the group if its throttled, or when empty.
 859          * The latter is a consequence of the former when a child group
 860          * get throttled and the current group doesn't have any other
 861          * active members.
 862          */
 863         if (group_rq && (rt_rq_throttled(group_rq) || !group_rq->rt_nr_running))
 864                 return;
 865
 866         if (!rt_rq->rt_nr_running)
 867                 list_add_leaf_rt_rq(rt_rq);
 868
 869         if (head)
 870                 list_add(&rt_se->run_list, queue);
 871         else
 872                 list_add_tail(&rt_se->run_list, queue);
 873         __set_bit(rt_se_prio(rt_se), array->bitmap);
 874
 875         inc_rt_tasks(rt_se, rt_rq);
 876 }
 877
 878 static void __dequeue_rt_entity(struct sched_rt_entity *rt_se)
 879 {
 880         struct rt_rq *rt_rq = rt_rq_of_se(rt_se);
 881         struct rt_prio_array *array = &rt_rq->active;
 882
 883         list_del_init(&rt_se->run_list);
 884         if (list_empty(array->queue + rt_se_prio(rt_se)))
 885                 __clear_bit(rt_se_prio(rt_se), array->bitmap);
 886
 887         dec_rt_tasks(rt_se, rt_rq);
 888         if (!rt_rq->rt_nr_running)
 889                 list_del_leaf_rt_rq(rt_rq);
 890 }
 891
 892 /*
 893  * Because the prio of an upper entry depends on the lower
 894  * entries, we must remove entries top - down.
 895  */
 896 static void dequeue_rt_stack(struct sched_rt_entity *rt_se)
 897 {
 898         struct sched_rt_entity *back = NULL;
 899
 900         for_each_sched_rt_entity(rt_se) {
 901                 rt_se->back = back;
 902                 back = rt_se;
 903         }
 904
 905         for (rt_se = back; rt_se; rt_se = rt_se->back) {
 906                 if (on_rt_rq(rt_se))
 907                         __dequeue_rt_entity(rt_se);
 908         }
 909 }
 910
 911 static void enqueue_rt_entity(struct sched_rt_entity *rt_se, bool head)
 912 {
 913         dequeue_rt_stack(rt_se);
 914         for_each_sched_rt_entity(rt_se)
 915                 __enqueue_rt_entity(rt_se, head);
 916 }
 917
 918 static void dequeue_rt_entity(struct sched_rt_entity *rt_se)
 919 {
 920         dequeue_rt_stack(rt_se);
 921
 922         for_each_sched_rt_entity(rt_se) {
 923                 struct rt_rq *rt_rq = group_rt_rq(rt_se);
 924
 925                 if (rt_rq && rt_rq->rt_nr_running)
 926                         __enqueue_rt_entity(rt_se, false);
 927         }
 928 }
 929
 930 /*
 931  * Adding/removing a task to/from a priority array:
 932  */
 933 static void
 934 enqueue_task_rt(struct rq *rq, struct task_struct *p, int flags)
 935 {
 936         struct sched_rt_entity *rt_se = &p->rt;
 937
 938         if (flags & ENQUEUE_WAKEUP)
 939                 rt_se->timeout = 0;
 940
 941         enqueue_rt_entity(rt_se, flags & ENQUEUE_HEAD);
 942
 943         if (!task_current(rq, p) && p->rt.nr_cpus_allowed > 1)
 944                 enqueue_pushable_task(rq, p);
 945 }
 946
 947 static void dequeue_task_rt(struct rq *rq, struct task_struct *p, int flags)
 948 {
 949         struct sched_rt_entity *rt_se = &p->rt;
 950
 951         update_curr_rt(rq);
 952         dequeue_rt_entity(rt_se);
 953
 954         dequeue_pushable_task(rq, p);
 955 }
 956
 957 /*
 958  * Put task to the end of the run list without the overhead of dequeue
 959  * followed by enqueue.
 960  */
 961 static void
 962 requeue_rt_entity(struct rt_rq *rt_rq, struct sched_rt_entity *rt_se, int head)
 963 {
 964         if (on_rt_rq(rt_se)) {
 965                 struct rt_prio_array *array = &rt_rq->active;
 966                 struct list_head *queue = array->queue + rt_se_prio(rt_se);
 967
 968                 if (head)
 969                         list_move(&rt_se->run_list, queue);
 970                 else
 971                         list_move_tail(&rt_se->run_list, queue);
 972         }
 973 }
 974
 975 static void requeue_task_rt(struct rq *rq, struct task_struct *p, int head)
 976 {
 977         struct sched_rt_entity *rt_se = &p->rt;
 978         struct rt_rq *rt_rq;
 979
 980         for_each_sched_rt_entity(rt_se) {
 981                 rt_rq = rt_rq_of_se(rt_se);
 982                 requeue_rt_entity(rt_rq, rt_se, head);
 983         }
 984 }
 985
 986 static void yield_task_rt(struct rq *rq)
 987 {
 988         requeue_task_rt(rq, rq->curr, 0);
 989 }
 990
 991 #ifdef CONFIG_SMP
 992 static int find_lowest_rq(struct task_struct *task);
 993
 994 static int
 995 select_task_rq_rt(struct rq *rq, struct task_struct *p, int sd_flag, int flags)
 996 {
 997         if (sd_flag != SD_BALANCE_WAKE)
 998                 return smp_processor_id();
 999
1000         /*
1001          * If the current task is an RT task, then
1002          * try to see if we can wake this RT task up on another
1003          * runqueue. Otherwise simply start this RT task
1004          * on its current runqueue.
1005          *
1006          * We want to avoid overloading runqueues. If the woken
1007          * task is a higher priority, then it will stay on this CPU
1008          * and the lower prio task should be moved to another CPU.
1009          * Even though this will probably make the lower prio task
1010          * lose its cache, we do not want to bounce a higher task
1011          * around just because it gave up its CPU, perhaps for a
1012          * lock?
1013          *
1014          * For equal prio tasks, we just let the scheduler sort it out.
1015          */
1016         if (unlikely(rt_task(rq->curr)) &&
1017             (rq->curr->rt.nr_cpus_allowed < 2 ||
1018              rq->curr->prio < p->prio) &&
1019             (p->rt.nr_cpus_allowed > 1)) {
1020                 int cpu = find_lowest_rq(p);
1021
1022                 return (cpu == -1) ? task_cpu(p) : cpu;
1023         }
1024
1025         /*
1026          * Otherwise, just let it ride on the affined RQ and the
1027          * post-schedule router will push the preempted task away
1028          */
1029         return task_cpu(p);
1030 }
1031
1032 static void check_preempt_equal_prio(struct rq *rq, struct task_struct *p)
1033 {
1034         if (rq->curr->rt.nr_cpus_allowed == 1)
1035                 return;
1036
1037         if (p->rt.nr_cpus_allowed != 1
1038             && cpupri_find(&rq->rd->cpupri, p, NULL))
1039                 return;
1040
1041         if (!cpupri_find(&rq->rd->cpupri, rq->curr, NULL))
1042                 return;
1043
1044         /*
1045          * There appears to be other cpus that can accept
1046          * current and none to run 'p', so lets reschedule
1047          * to try and push current away:
1048          */
1049         requeue_task_rt(rq, p, 1);
1050         resched_task(rq->curr);
1051 }
1052
1053 #endif /* CONFIG_SMP */
1054
1055 /*
1056  * Preempt the current task with a newly woken task if needed:
1057  */
1058 static void check_preempt_curr_rt(struct rq *rq, struct task_struct *p, int flags)
1059 {
1060         if (p->prio < rq->curr->prio) {
1061                 resched_task(rq->curr);
1062                 return;
1063         }
1064
1065 #ifdef CONFIG_SMP
1066         /*
1067          * If:
1068          *
1069          * - the newly woken task is of equal priority to the current task
1070          * - the newly woken task is non-migratable while current is migratable
1071          * - current will be preempted on the next reschedule
1072          *
1073          * we should check to see if current can readily move to a different
1074          * cpu.  If so, we will reschedule to allow the push logic to try
1075          * to move current somewhere else, making room for our non-migratable
1076          * task.
1077          */
1078         if (p->prio == rq->curr->prio && !need_resched())
1079                 check_preempt_equal_prio(rq, p);
1080 #endif
1081 }
1082
1083 static struct sched_rt_entity *pick_next_rt_entity(struct rq *rq,
1084                                                    struct rt_rq *rt_rq)
1085 {
1086         struct rt_prio_array *array = &rt_rq->active;
1087         struct sched_rt_entity *next = NULL;
1088         struct list_head *queue;
1089         int idx;
1090
1091         idx = sched_find_first_bit(array->bitmap);
1092         BUG_ON(idx >= MAX_RT_PRIO);
1093
1094         queue = array->queue + idx;
1095         next = list_entry(queue->next, struct sched_rt_entity, run_list);
1096
1097         return next;
1098 }
1099
1100 static struct task_struct *_pick_next_task_rt(struct rq *rq)
1101 {
1102         struct sched_rt_entity *rt_se;
1103         struct task_struct *p;
1104         struct rt_rq *rt_rq;
1105
1106         rt_rq = &rq->rt;
1107
1108         if (unlikely(!rt_rq->rt_nr_running))
1109                 return NULL;
1110
1111         if (rt_rq_throttled(rt_rq))
1112                 return NULL;
1113
1114         do {
1115                 rt_se = pick_next_rt_entity(rq, rt_rq);
1116                 BUG_ON(!rt_se);
1117                 rt_rq = group_rt_rq(rt_se);
1118         } while (rt_rq);
1119
1120         p = rt_task_of(rt_se);
1121         p->se.exec_start = rq->clock_task;
1122
1123         return p;
1124 }
1125
1126 static struct task_struct *pick_next_task_rt(struct rq *rq)
1127 {
1128         struct task_struct *p = _pick_next_task_rt(rq);
1129
1130         /* The running task is never eligible for pushing */
1131         if (p)
1132                 dequeue_pushable_task(rq, p);
1133
1134 #ifdef CONFIG_SMP
1135         /*
1136          * We detect this state here so that we can avoid taking the RQ
1137          * lock again later if there is no need to push
1138          */
1139         rq->post_schedule = has_pushable_tasks(rq);
1140 #endif
1141
1142         return p;
1143 }
1144
1145 static void put_prev_task_rt(struct rq *rq, struct task_struct *p)
1146 {
1147         update_curr_rt(rq);
1148         p->se.exec_start = 0;
1149
1150         /*
1151          * The previous task needs to be made eligible for pushing
1152          * if it is still active
1153          */
1154         if (p->se.on_rq && p->rt.nr_cpus_allowed > 1)
1155                 enqueue_pushable_task(rq, p);
1156 }
1157
1158 #ifdef CONFIG_SMP
1159
1160 /* Only try algorithms three times */
1161 #define RT_MAX_TRIES 3
1162
1163 static void deactivate_task(struct rq *rq, struct task_struct *p, int sleep);
1164
1165 static int pick_rt_task(struct rq *rq, struct task_struct *p, int cpu)
1166 {
1167         if (!task_running(rq, p) &&
1168             (cpu < 0 || cpumask_test_cpu(cpu, &p->cpus_allowed)) &&
1169             (p->rt.nr_cpus_allowed > 1))
1170                 return 1;
1171         return 0;
1172 }
1173
1174 /* Return the second highest RT task, NULL otherwise */
1175 static struct task_struct *pick_next_highest_task_rt(struct rq *rq, int cpu)
1176 {
1177         struct task_struct *next = NULL;
1178         struct sched_rt_entity *rt_se;
1179         struct rt_prio_array *array;
1180         struct rt_rq *rt_rq;
1181         int idx;
1182
1183         for_each_leaf_rt_rq(rt_rq, rq) {
1184                 array = &rt_rq->active;
1185                 idx = sched_find_first_bit(array->bitmap);
1186 next_idx:
1187                 if (idx >= MAX_RT_PRIO)
1188                         continue;
1189                 if (next && next->prio < idx)
1190                         continue;
1191                 list_for_each_entry(rt_se, array->queue + idx, run_list) {
1192                         struct task_struct *p;
1193
1194                         if (!rt_entity_is_task(rt_se))
1195                                 continue;
1196
1197                         p = rt_task_of(rt_se);
1198                         if (pick_rt_task(rq, p, cpu)) {
1199                                 next = p;
1200                                 break;
1201                         }
1202                 }
1203                 if (!next) {
1204                         idx = find_next_bit(array->bitmap, MAX_RT_PRIO, idx+1);
1205                         goto next_idx;
1206                 }
1207         }
1208
1209         return next;
1210 }
1211
1212 static DEFINE_PER_CPU(cpumask_var_t, local_cpu_mask);
1213
1214 static int find_lowest_rq(struct task_struct *task)
1215 {
1216         struct sched_domain *sd;
1217         struct cpumask *lowest_mask = __get_cpu_var(local_cpu_mask);
1218         int this_cpu = smp_processor_id();
1219         int cpu      = task_cpu(task);
1220
1221         if (task->rt.nr_cpus_allowed == 1)
1222                 return -1; /* No other targets possible */
1223
1224         if (!cpupri_find(&task_rq(task)->rd->cpupri, task, lowest_mask))
1225                 return -1; /* No targets found */
1226
1227         /*
1228          * At this point we have built a mask of cpus representing the
1229          * lowest priority tasks in the system.  Now we want to elect
1230          * the best one based on our affinity and topology.
1231          *
1232          * We prioritize the last cpu that the task executed on since
1233          * it is most likely cache-hot in that location.
1234          */
1235         if (cpumask_test_cpu(cpu, lowest_mask))
1236                 return cpu;
1237
1238         /*
1239          * Otherwise, we consult the sched_domains span maps to figure
1240          * out which cpu is logically closest to our hot cache data.
1241          */
1242         if (!cpumask_test_cpu(this_cpu, lowest_mask))
1243                 this_cpu = -1; /* Skip this_cpu opt if not among lowest */
1244
1245         for_each_domain(cpu, sd) {
1246                 if (sd->flags & SD_WAKE_AFFINE) {
1247                         int best_cpu;
1248
1249                         /*
1250                          * "this_cpu" is cheaper to preempt than a
1251                          * remote processor.
1252                          */
1253                         if (this_cpu != -1 &&
1254                             cpumask_test_cpu(this_cpu, sched_domain_span(sd)))
1255                                 return this_cpu;
1256
1257                         best_cpu = cpumask_first_and(lowest_mask,
1258                                                      sched_domain_span(sd));
1259                         if (best_cpu < nr_cpu_ids)
1260                                 return best_cpu;
1261                 }
1262         }
1263
1264         /*
1265          * And finally, if there were no matches within the domains
1266          * just give the caller *something* to work with from the compatible
1267          * locations.
1268          */
1269         if (this_cpu != -1)
1270                 return this_cpu;
1271
1272         cpu = cpumask_any(lowest_mask);
1273         if (cpu < nr_cpu_ids)
1274                 return cpu;
1275         return -1;
1276 }
1277
1278 /* Will lock the rq it finds */
1279 static struct rq *find_lock_lowest_rq(struct task_struct *task, struct rq *rq)
1280 {
1281         struct rq *lowest_rq = NULL;
1282         int tries;
1283         int cpu;
1284
1285         for (tries = 0; tries < RT_MAX_TRIES; tries++) {
1286                 cpu = find_lowest_rq(task);
1287
1288                 if ((cpu == -1) || (cpu == rq->cpu))
1289                         break;
1290
1291                 lowest_rq = cpu_rq(cpu);
1292
1293                 /* if the prio of this runqueue changed, try again */
1294                 if (double_lock_balance(rq, lowest_rq)) {
1295                         /*
1296                          * We had to unlock the run queue. In
1297                          * the mean time, task could have
1298                          * migrated already or had its affinity changed.
1299                          * Also make sure that it wasn't scheduled on its rq.
1300                          */
1301                         if (unlikely(task_rq(task) != rq ||
1302                                      !cpumask_test_cpu(lowest_rq->cpu,
1303                                                        &task->cpus_allowed) ||
1304                                      task_running(rq, task) ||
1305                                      !task->se.on_rq)) {
1306
1307                                 raw_spin_unlock(&lowest_rq->lock);
1308                                 lowest_rq = NULL;
1309                                 break;
1310                         }
1311                 }
1312
1313                 /* If this rq is still suitable use it. */
1314                 if (lowest_rq->rt.highest_prio.curr > task->prio)
1315                         break;
1316
1317                 /* try again */
1318                 double_unlock_balance(rq, lowest_rq);
1319                 lowest_rq = NULL;
1320         }
1321
1322         return lowest_rq;
1323 }
1324
1325 static struct task_struct *pick_next_pushable_task(struct rq *rq)
1326 {
1327         struct task_struct *p;
1328
1329         if (!has_pushable_tasks(rq))
1330                 return NULL;
1331
1332         p = plist_first_entry(&rq->rt.pushable_tasks,
1333                               struct task_struct, pushable_tasks);
1334
1335         BUG_ON(rq->cpu != task_cpu(p));
1336         BUG_ON(task_current(rq, p));
1337         BUG_ON(p->rt.nr_cpus_allowed <= 1);
1338
1339         BUG_ON(!p->se.on_rq);
1340         BUG_ON(!rt_task(p));
1341
1342         return p;
1343 }
1344
1345 /*
1346  * If the current CPU has more than one RT task, see if the non
1347  * running task can migrate over to a CPU that is running a task
1348  * of lesser priority.
1349  */
1350 static int push_rt_task(struct rq *rq)
1351 {
1352         struct task_struct *next_task;
1353         struct rq *lowest_rq;
1354
1355         if (!rq->rt.overloaded)
1356                 return 0;
1357
1358         next_task = pick_next_pushable_task(rq);
1359         if (!next_task)
1360                 return 0;
1361
1362 retry:
1363         if (unlikely(next_task == rq->curr)) {
1364                 WARN_ON(1);
1365                 return 0;
1366         }
1367
1368         /*
1369          * It's possible that the next_task slipped in of
1370          * higher priority than current. If that's the case
1371          * just reschedule current.
1372          */
1373         if (unlikely(next_task->prio < rq->curr->prio)) {
1374                 resched_task(rq->curr);
1375                 return 0;
1376         }
1377
1378         /* We might release rq lock */
1379         get_task_struct(next_task);
1380
1381         /* find_lock_lowest_rq locks the rq if found */
1382         lowest_rq = find_lock_lowest_rq(next_task, rq);
1383         if (!lowest_rq) {
1384                 struct task_struct *task;
1385                 /*
1386                  * find lock_lowest_rq releases rq->lock
1387                  * so it is possible that next_task has migrated.
1388                  *
1389                  * We need to make sure that the task is still on the same
1390                  * run-queue and is also still the next task eligible for
1391                  * pushing.
1392                  */
1393                 task = pick_next_pushable_task(rq);
1394                 if (task_cpu(next_task) == rq->cpu && task == next_task) {
1395                         /*
1396                          * If we get here, the task hasn't moved at all, but
1397                          * it has failed to push.  We will not try again,
1398                          * since the other cpus will pull from us when they
1399                          * are ready.
1400                          */
1401                         dequeue_pushable_task(rq, next_task);
1402                         goto out;
1403                 }
1404
1405                 if (!task)
1406                         /* No more tasks, just exit */
1407                         goto out;
1408
1409                 /*
1410                  * Something has shifted, try again.
1411                  */
1412                 put_task_struct(next_task);
1413                 next_task = task;
1414                 goto retry;
1415         }
1416
1417         deactivate_task(rq, next_task, 0);
1418         set_task_cpu(next_task, lowest_rq->cpu);
1419         activate_task(lowest_rq, next_task, 0);
1420
1421         resched_task(lowest_rq->curr);
1422
1423         double_unlock_balance(rq, lowest_rq);
1424
1425 out:
1426         put_task_struct(next_task);
1427
1428         return 1;
1429 }
1430
1431 static void push_rt_tasks(struct rq *rq)
1432 {
1433         /* push_rt_task will return true if it moved an RT */
1434         while (push_rt_task(rq))
1435                 ;
1436 }
1437
1438 static int pull_rt_task(struct rq *this_rq)
1439 {
1440         int this_cpu = this_rq->cpu, ret = 0, cpu;
1441         struct task_struct *p;
1442         struct rq *src_rq;
1443
1444         if (likely(!rt_overloaded(this_rq)))
1445                 return 0;
1446
1447         for_each_cpu(cpu, this_rq->rd->rto_mask) {
1448                 if (this_cpu == cpu)
1449                         continue;
1450
1451                 src_rq = cpu_rq(cpu);
1452
1453                 /*
1454                  * Don't bother taking the src_rq->lock if the next highest
1455                  * task is known to be lower-priority than our current task.
1456                  * This may look racy, but if this value is about to go
1457                  * logically higher, the src_rq will push this task away.
1458                  * And if its going logically lower, we do not care
1459                  */
1460                 if (src_rq->rt.highest_prio.next >=
1461                     this_rq->rt.highest_prio.curr)
1462                         continue;
1463
1464                 /*
1465                  * We can potentially drop this_rq's lock in
1466                  * double_lock_balance, and another CPU could
1467                  * alter this_rq
1468                  */
1469                 double_lock_balance(this_rq, src_rq);
1470
1471                 /*
1472                  * Are there still pullable RT tasks?
1473                  */
1474                 if (src_rq->rt.rt_nr_running <= 1)
1475                         goto skip;
1476
1477                 p = pick_next_highest_task_rt(src_rq, this_cpu);
1478
1479                 /*
1480                  * Do we have an RT task that preempts
1481                  * the to-be-scheduled task?
1482                  */
1483                 if (p && (p->prio < this_rq->rt.highest_prio.curr)) {
1484                         WARN_ON(p == src_rq->curr);
1485                         WARN_ON(!p->se.on_rq);
1486
1487                         /*
1488                          * There's a chance that p is higher in priority
1489                          * than what's currently running on its cpu.
1490                          * This is just that p is wakeing up and hasn't
1491                          * had a chance to schedule. We only pull
1492                          * p if it is lower in priority than the
1493                          * current task on the run queue
1494                          */
1495                         if (p->prio < src_rq->curr->prio)
1496                                 goto skip;
1497
1498                         ret = 1;
1499
1500                         deactivate_task(src_rq, p, 0);
1501                         set_task_cpu(p, this_cpu);
1502                         activate_task(this_rq, p, 0);
1503                         /*
1504                          * We continue with the search, just in
1505                          * case there's an even higher prio task
1506                          * in another runqueue. (low likelihood
1507                          * but possible)
1508                          */
1509                 }
1510 skip:
1511                 double_unlock_balance(this_rq, src_rq);
1512         }
1513
1514         return ret;
1515 }
1516
1517 static void pre_schedule_rt(struct rq *rq, struct task_struct *prev)
1518 {
1519         /* Try to pull RT tasks here if we lower this rq's prio */
1520         if (unlikely(rt_task(prev)) && rq->rt.highest_prio.curr > prev->prio)
1521                 pull_rt_task(rq);
1522 }
1523
1524 static void post_schedule_rt(struct rq *rq)
1525 {
1526         push_rt_tasks(rq);
1527 }
1528
1529 /*
1530  * If we are not running and we are not going to reschedule soon, we should
1531  * try to push tasks away now
1532  */
1533 static void task_woken_rt(struct rq *rq, struct task_struct *p)
1534 {
1535         if (!task_running(rq, p) &&
1536             !test_tsk_need_resched(rq->curr) &&
1537             has_pushable_tasks(rq) &&
1538             p->rt.nr_cpus_allowed > 1 &&
1539             rt_task(rq->curr) &&
1540             (rq->curr->rt.nr_cpus_allowed < 2 ||
1541              rq->curr->prio < p->prio))
1542                 push_rt_tasks(rq);
1543 }
1544
1545 static void set_cpus_allowed_rt(struct task_struct *p,
1546                                 const struct cpumask *new_mask)
1547 {
1548         int weight = cpumask_weight(new_mask);
1549
1550         BUG_ON(!rt_task(p));
1551
1552         /*
1553          * Update the migration status of the RQ if we have an RT task
1554          * which is running AND changing its weight value.
1555          */
1556         if (p->se.on_rq && (weight != p->rt.nr_cpus_allowed)) {
1557                 struct rq *rq = task_rq(p);
1558
1559                 if (!task_current(rq, p)) {
1560                         /*
1561                          * Make sure we dequeue this task from the pushable list
1562                          * before going further.  It will either remain off of
1563                          * the list because we are no longer pushable, or it
1564                          * will be requeued.
1565                          */
1566                         if (p->rt.nr_cpus_allowed > 1)
1567                                 dequeue_pushable_task(rq, p);
1568
1569                         /*
1570                          * Requeue if our weight is changing and still > 1
1571                          */
1572                         if (weight > 1)
1573                                 enqueue_pushable_task(rq, p);
1574
1575                 }
1576
1577                 if ((p->rt.nr_cpus_allowed <= 1) && (weight > 1)) {
1578                         rq->rt.rt_nr_migratory++;
1579                 } else if ((p->rt.nr_cpus_allowed > 1) && (weight <= 1)) {
1580                         BUG_ON(!rq->rt.rt_nr_migratory);
1581                         rq->rt.rt_nr_migratory--;
1582                 }
1583
1584                 update_rt_migration(&rq->rt);
1585         }
1586
1587         cpumask_copy(&p->cpus_allowed, new_mask);
1588         p->rt.nr_cpus_allowed = weight;
1589 }
1590
1591 /* Assumes rq->lock is held */
1592 static void rq_online_rt(struct rq *rq)
1593 {
1594         if (rq->rt.overloaded)
1595                 rt_set_overload(rq);
1596
1597         __enable_runtime(rq);
1598
1599         cpupri_set(&rq->rd->cpupri, rq->cpu, rq->rt.highest_prio.curr);
1600 }
1601
1602 /* Assumes rq->lock is held */
1603 static void rq_offline_rt(struct rq *rq)
1604 {
1605         if (rq->rt.overloaded)
1606                 rt_clear_overload(rq);
1607
1608         __disable_runtime(rq);
1609
1610         cpupri_set(&rq->rd->cpupri, rq->cpu, CPUPRI_INVALID);
1611 }
1612
1613 /*
1614  * When switch from the rt queue, we bring ourselves to a position
1615  * that we might want to pull RT tasks from other runqueues.
1616  */
1617 static void switched_from_rt(struct rq *rq, struct task_struct *p)
1618 {
1619         /*
1620          * If there are other RT tasks then we will reschedule
1621          * and the scheduling of the other RT tasks will handle
1622          * the balancing. But if we are the last RT task
1623          * we may need to handle the pulling of RT tasks
1624          * now.
1625          */
1626         if (p->se.on_rq && !rq->rt.rt_nr_running)
1627                 pull_rt_task(rq);
1628 }
1629
1630 static inline void init_sched_rt_class(void)
1631 {
1632         unsigned int i;
1633
1634         for_each_possible_cpu(i)
1635                 zalloc_cpumask_var_node(&per_cpu(local_cpu_mask, i),
1636                                         GFP_KERNEL, cpu_to_node(i));
1637 }
1638 #endif /* CONFIG_SMP */
1639
1640 /*
1641  * When switching a task to RT, we may overload the runqueue
1642  * with RT tasks. In this case we try to push them off to
1643  * other runqueues.
1644  */
1645 static void switched_to_rt(struct rq *rq, struct task_struct *p)
1646 {
1647         int check_resched = 1;
1648
1649         /*
1650          * If we are already running, then there's nothing
1651          * that needs to be done. But if we are not running
1652          * we may need to preempt the current running task.
1653          * If that current running task is also an RT task
1654          * then see if we can move to another run queue.
1655          */
1656         if (p->se.on_rq && rq->curr != p) {
1657 #ifdef CONFIG_SMP
1658                 if (rq->rt.overloaded && push_rt_task(rq) &&
1659                     /* Don't resched if we changed runqueues */
1660                     rq != task_rq(p))
1661                         check_resched = 0;
1662 #endif /* CONFIG_SMP */
1663                 if (check_resched && p->prio < rq->curr->prio)
1664                         resched_task(rq->curr);
1665         }
1666 }
1667
1668 /*
1669  * Priority of the task has changed. This may cause
1670  * us to initiate a push or pull.
1671  */
1672 static void
1673 prio_changed_rt(struct rq *rq, struct task_struct *p, int oldprio)
1674 {
1675         if (!p->se.on_rq)
1676                 return;
1677
1678         if (rq->curr == p) {
1679 #ifdef CONFIG_SMP
1680                 /*
1681                  * If our priority decreases while running, we
1682                  * may need to pull tasks to this runqueue.
1683                  */
1684                 if (oldprio < p->prio)
1685                         pull_rt_task(rq);
1686                 /*
1687                  * If there's a higher priority task waiting to run
1688                  * then reschedule. Note, the above pull_rt_task
1689                  * can release the rq lock and p could migrate.
1690                  * Only reschedule if p is still on the same runqueue.
1691                  */
1692                 if (p->prio > rq->rt.highest_prio.curr && rq->curr == p)
1693                         resched_task(p);
1694 #else
1695                 /* For UP simply resched on drop of prio */
1696                 if (oldprio < p->prio)
1697                         resched_task(p);
1698 #endif /* CONFIG_SMP */
1699         } else {
1700                 /*
1701                  * This task is not running, but if it is
1702                  * greater than the current running task
1703                  * then reschedule.
1704                  */
1705                 if (p->prio < rq->curr->prio)
1706                         resched_task(rq->curr);
1707         }
1708 }
1709
1710 static void watchdog(struct rq *rq, struct task_struct *p)
1711 {
1712         unsigned long soft, hard;
1713
1714         /* max may change after cur was read, this will be fixed next tick */
1715         soft = task_rlimit(p, RLIMIT_RTTIME);
1716         hard = task_rlimit_max(p, RLIMIT_RTTIME);
1717
1718         if (soft != RLIM_INFINITY) {
1719                 unsigned long next;
1720
1721                 p->rt.timeout++;
1722                 next = DIV_ROUND_UP(min(soft, hard), USEC_PER_SEC/HZ);
1723                 if (p->rt.timeout > next)
1724                         p->cputime_expires.sched_exp = p->se.sum_exec_runtime;
1725         }
1726 }
1727
1728 static void task_tick_rt(struct rq *rq, struct task_struct *p, int queued)
1729 {
1730         update_curr_rt(rq);
1731
1732         watchdog(rq, p);
1733
1734         /*
1735          * RR tasks need a special form of timeslice management.
1736          * FIFO tasks have no timeslices.
1737          */
1738         if (p->policy != SCHED_RR)
1739                 return;
1740
1741         if (--p->rt.time_slice)
1742                 return;
1743
1744         p->rt.time_slice = DEF_TIMESLICE;
1745
1746         /*
1747          * Requeue to the end of queue if we are not the only element
1748          * on the queue:
1749          */
1750         if (p->rt.run_list.prev != p->rt.run_list.next) {
1751                 requeue_task_rt(rq, p, 0);
1752                 set_tsk_need_resched(p);
1753         }
1754 }
1755
1756 static void set_curr_task_rt(struct rq *rq)
1757 {
1758         struct task_struct *p = rq->curr;
1759
1760         p->se.exec_start = rq->clock_task;
1761
1762         /* The running task is never eligible for pushing */
1763         dequeue_pushable_task(rq, p);
1764 }
1765
1766 static unsigned int get_rr_interval_rt(struct rq *rq, struct task_struct *task)
1767 {
1768         /*
1769          * Time slice is 0 for SCHED_FIFO tasks
1770          */
1771         if (task->policy == SCHED_RR)
1772                 return DEF_TIMESLICE;
1773         else
1774                 return 0;
1775 }
1776
1777 static const struct sched_class rt_sched_class = {
1778         .next                   = &fair_sched_class,
1779         .enqueue_task           = enqueue_task_rt,
1780         .dequeue_task           = dequeue_task_rt,
1781         .yield_task             = yield_task_rt,
1782
1783         .check_preempt_curr     = check_preempt_curr_rt,
1784
1785         .pick_next_task         = pick_next_task_rt,
1786         .put_prev_task          = put_prev_task_rt,
1787
1788 #ifdef CONFIG_SMP
1789         .select_task_rq         = select_task_rq_rt,
1790
1791         .set_cpus_allowed       = set_cpus_allowed_rt,
1792         .rq_online              = rq_online_rt,
1793         .rq_offline             = rq_offline_rt,
1794         .pre_schedule           = pre_schedule_rt,
1795         .post_schedule          = post_schedule_rt,
1796         .task_woken             = task_woken_rt,
1797         .switched_from          = switched_from_rt,
1798 #endif
1799
1800         .set_curr_task          = set_curr_task_rt,
1801         .task_tick              = task_tick_rt,
1802
1803         .get_rr_interval        = get_rr_interval_rt,
1804
1805         .prio_changed           = prio_changed_rt,
1806         .switched_to            = switched_to_rt,
1807 };
1808
1809 #ifdef CONFIG_SCHED_DEBUG
1810 extern void print_rt_rq(struct seq_file *m, int cpu, struct rt_rq *rt_rq);
1811
1812 static void print_rt_stats(struct seq_file *m, int cpu)
1813 {
1814         rt_rq_iter_t iter;
1815         struct rt_rq *rt_rq;
1816
1817         rcu_read_lock();
1818         for_each_rt_rq(rt_rq, iter, cpu_rq(cpu))
1819                 print_rt_rq(m, cpu, rt_rq);
1820         rcu_read_unlock();
1821 }
1822 #endif /* CONFIG_SCHED_DEBUG */
1823