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