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