/*
   * Real-Time Scheduling Class (mapped to the SCHED_FIFO and SCHED_RR
   * policies)
   */

  #include "sched.h"
  
  #include <linux/slab.h>

  #include <linux/irq_work.h>

  int sched_rr_timeslice = RR_TIMESLICE;

  static int do_sched_rt_period_timer(struct rt_bandwidth *rt_b, int overrun);
  
  struct rt_bandwidth def_rt_bandwidth;
  
  static enum hrtimer_restart sched_rt_period_timer(struct hrtimer *timer)
  {
  	struct rt_bandwidth *rt_b =
  		container_of(timer, struct rt_bandwidth, rt_period_timer);

  	int idle = 0;

  	int overrun;

  	raw_spin_lock(&rt_b->rt_runtime_lock);

  	for (;;) {

  		overrun = hrtimer_forward_now(timer, rt_b->rt_period);

  		if (!overrun)
  			break;

  		raw_spin_unlock(&rt_b->rt_runtime_lock);

  		idle = do_sched_rt_period_timer(rt_b, overrun);

  		raw_spin_lock(&rt_b->rt_runtime_lock);

  	}

  	if (idle)
  		rt_b->rt_period_active = 0;

  	raw_spin_unlock(&rt_b->rt_runtime_lock);

  
  	return idle ? HRTIMER_NORESTART : HRTIMER_RESTART;
  }
  
  void init_rt_bandwidth(struct rt_bandwidth *rt_b, u64 period, u64 runtime)
  {
  	rt_b->rt_period = ns_to_ktime(period);
  	rt_b->rt_runtime = runtime;
  
  	raw_spin_lock_init(&rt_b->rt_runtime_lock);
  
  	hrtimer_init(&rt_b->rt_period_timer,
  			CLOCK_MONOTONIC, HRTIMER_MODE_REL);
  	rt_b->rt_period_timer.function = sched_rt_period_timer;
  }
  
  static void start_rt_bandwidth(struct rt_bandwidth *rt_b)
  {
  	if (!rt_bandwidth_enabled() || rt_b->rt_runtime == RUNTIME_INF)
  		return;

  	raw_spin_lock(&rt_b->rt_runtime_lock);

  	if (!rt_b->rt_period_active) {
  		rt_b->rt_period_active = 1;

  		/*
  		 * SCHED_DEADLINE updates the bandwidth, as a run away
  		 * RT task with a DL task could hog a CPU. But DL does
  		 * not reset the period. If a deadline task was running
  		 * without an RT task running, it can cause RT tasks to
  		 * throttle when they start up. Kick the timer right away
  		 * to update the period.
  		 */
  		hrtimer_forward_now(&rt_b->rt_period_timer, ns_to_ktime(0));

  		hrtimer_start_expires(&rt_b->rt_period_timer, HRTIMER_MODE_ABS_PINNED);
  	}

  	raw_spin_unlock(&rt_b->rt_runtime_lock);
  }

  #if defined(CONFIG_SMP) && defined(HAVE_RT_PUSH_IPI)

  static void push_irq_work_func(struct irq_work *work);
  #endif

  void init_rt_rq(struct rt_rq *rt_rq)

  {
  	struct rt_prio_array *array;
  	int i;
  
  	array = &rt_rq->active;
  	for (i = 0; i < MAX_RT_PRIO; i++) {
  		INIT_LIST_HEAD(array->queue + i);
  		__clear_bit(i, array->bitmap);
  	}
  	/* delimiter for bitsearch: */
  	__set_bit(MAX_RT_PRIO, array->bitmap);
  
  #if defined CONFIG_SMP
  	rt_rq->highest_prio.curr = MAX_RT_PRIO;
  	rt_rq->highest_prio.next = MAX_RT_PRIO;
  	rt_rq->rt_nr_migratory = 0;
  	rt_rq->overloaded = 0;
  	plist_head_init(&rt_rq->pushable_tasks);

  
  #ifdef HAVE_RT_PUSH_IPI
  	rt_rq->push_flags = 0;
  	rt_rq->push_cpu = nr_cpu_ids;
  	raw_spin_lock_init(&rt_rq->push_lock);
  	init_irq_work(&rt_rq->push_work, push_irq_work_func);

  #endif

  #endif /* CONFIG_SMP */

  	/* We start is dequeued state, because no RT tasks are queued */
  	rt_rq->rt_queued = 0;

  
  	rt_rq->rt_time = 0;
  	rt_rq->rt_throttled = 0;
  	rt_rq->rt_runtime = 0;
  	raw_spin_lock_init(&rt_rq->rt_runtime_lock);
  }

  #ifdef CONFIG_RT_GROUP_SCHED

  static void destroy_rt_bandwidth(struct rt_bandwidth *rt_b)
  {
  	hrtimer_cancel(&rt_b->rt_period_timer);
  }

  
  #define rt_entity_is_task(rt_se) (!(rt_se)->my_q)

  static inline struct task_struct *rt_task_of(struct sched_rt_entity *rt_se)
  {

  #ifdef CONFIG_SCHED_DEBUG
  	WARN_ON_ONCE(!rt_entity_is_task(rt_se));
  #endif

  	return container_of(rt_se, struct task_struct, rt);
  }

  static inline struct rq *rq_of_rt_rq(struct rt_rq *rt_rq)
  {
  	return rt_rq->rq;
  }
  
  static inline struct rt_rq *rt_rq_of_se(struct sched_rt_entity *rt_se)
  {
  	return rt_se->rt_rq;
  }

  static inline struct rq *rq_of_rt_se(struct sched_rt_entity *rt_se)
  {
  	struct rt_rq *rt_rq = rt_se->rt_rq;
  
  	return rt_rq->rq;
  }

  void free_rt_sched_group(struct task_group *tg)
  {
  	int i;
  
  	if (tg->rt_se)
  		destroy_rt_bandwidth(&tg->rt_bandwidth);
  
  	for_each_possible_cpu(i) {
  		if (tg->rt_rq)
  			kfree(tg->rt_rq[i]);
  		if (tg->rt_se)
  			kfree(tg->rt_se[i]);
  	}
  
  	kfree(tg->rt_rq);
  	kfree(tg->rt_se);
  }
  
  void init_tg_rt_entry(struct task_group *tg, struct rt_rq *rt_rq,
  		struct sched_rt_entity *rt_se, int cpu,
  		struct sched_rt_entity *parent)
  {
  	struct rq *rq = cpu_rq(cpu);
  
  	rt_rq->highest_prio.curr = MAX_RT_PRIO;
  	rt_rq->rt_nr_boosted = 0;
  	rt_rq->rq = rq;
  	rt_rq->tg = tg;
  
  	tg->rt_rq[cpu] = rt_rq;
  	tg->rt_se[cpu] = rt_se;
  
  	if (!rt_se)
  		return;
  
  	if (!parent)
  		rt_se->rt_rq = &rq->rt;
  	else
  		rt_se->rt_rq = parent->my_q;
  
  	rt_se->my_q = rt_rq;
  	rt_se->parent = parent;
  	INIT_LIST_HEAD(&rt_se->run_list);
  }
  
  int alloc_rt_sched_group(struct task_group *tg, struct task_group *parent)
  {
  	struct rt_rq *rt_rq;
  	struct sched_rt_entity *rt_se;
  	int i;
  
  	tg->rt_rq = kzalloc(sizeof(rt_rq) * nr_cpu_ids, GFP_KERNEL);
  	if (!tg->rt_rq)
  		goto err;
  	tg->rt_se = kzalloc(sizeof(rt_se) * nr_cpu_ids, GFP_KERNEL);
  	if (!tg->rt_se)
  		goto err;
  
  	init_rt_bandwidth(&tg->rt_bandwidth,
  			ktime_to_ns(def_rt_bandwidth.rt_period), 0);
  
  	for_each_possible_cpu(i) {
  		rt_rq = kzalloc_node(sizeof(struct rt_rq),
  				     GFP_KERNEL, cpu_to_node(i));
  		if (!rt_rq)
  			goto err;
  
  		rt_se = kzalloc_node(sizeof(struct sched_rt_entity),
  				     GFP_KERNEL, cpu_to_node(i));
  		if (!rt_se)
  			goto err_free_rq;

  		init_rt_rq(rt_rq);

  		rt_rq->rt_runtime = tg->rt_bandwidth.rt_runtime;
  		init_tg_rt_entry(tg, rt_rq, rt_se, i, parent->rt_se[i]);
  	}
  
  	return 1;
  
  err_free_rq:
  	kfree(rt_rq);
  err:
  	return 0;
  }

  #else /* CONFIG_RT_GROUP_SCHED */

  #define rt_entity_is_task(rt_se) (1)

  static inline struct task_struct *rt_task_of(struct sched_rt_entity *rt_se)
  {
  	return container_of(rt_se, struct task_struct, rt);
  }

  static inline struct rq *rq_of_rt_rq(struct rt_rq *rt_rq)
  {
  	return container_of(rt_rq, struct rq, rt);
  }

  static inline struct rq *rq_of_rt_se(struct sched_rt_entity *rt_se)

  {
  	struct task_struct *p = rt_task_of(rt_se);

  
  	return task_rq(p);
  }
  
  static inline struct rt_rq *rt_rq_of_se(struct sched_rt_entity *rt_se)
  {
  	struct rq *rq = rq_of_rt_se(rt_se);

  
  	return &rq->rt;
  }

  void free_rt_sched_group(struct task_group *tg) { }
  
  int alloc_rt_sched_group(struct task_group *tg, struct task_group *parent)
  {
  	return 1;
  }

  #endif /* CONFIG_RT_GROUP_SCHED */

  #ifdef CONFIG_SMP

  static void pull_rt_task(struct rq *this_rq);

  static inline bool need_pull_rt_task(struct rq *rq, struct task_struct *prev)
  {
  	/* Try to pull RT tasks here if we lower this rq's prio */
  	return rq->rt.highest_prio.curr > prev->prio;
  }

  static inline int rt_overloaded(struct rq *rq)

  {

  	return atomic_read(&rq->rd->rto_count);

  }

  static inline void rt_set_overload(struct rq *rq)
  {

  	if (!rq->online)
  		return;

  	cpumask_set_cpu(rq->cpu, rq->rd->rto_mask);

  	/*
  	 * Make sure the mask is visible before we set
  	 * the overload count. That is checked to determine
  	 * if we should look at the mask. It would be a shame
  	 * if we looked at the mask, but the mask was not
  	 * updated yet.

  	 *
  	 * Matched by the barrier in pull_rt_task().

  	 */

  	smp_wmb();

  	atomic_inc(&rq->rd->rto_count);

  }

  static inline void rt_clear_overload(struct rq *rq)
  {

  	if (!rq->online)
  		return;

  	/* the order here really doesn't matter */

  	atomic_dec(&rq->rd->rto_count);

  	cpumask_clear_cpu(rq->cpu, rq->rd->rto_mask);

  }

  static void update_rt_migration(struct rt_rq *rt_rq)

  {

  	if (rt_rq->rt_nr_migratory && rt_rq->rt_nr_total > 1) {

  		if (!rt_rq->overloaded) {
  			rt_set_overload(rq_of_rt_rq(rt_rq));
  			rt_rq->overloaded = 1;

  		}

  	} else if (rt_rq->overloaded) {
  		rt_clear_overload(rq_of_rt_rq(rt_rq));
  		rt_rq->overloaded = 0;

  	}

  }

  static void inc_rt_migration(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
  {

  	struct task_struct *p;

  	if (!rt_entity_is_task(rt_se))
  		return;

  	p = rt_task_of(rt_se);

  	rt_rq = &rq_of_rt_rq(rt_rq)->rt;
  
  	rt_rq->rt_nr_total++;

  	if (tsk_nr_cpus_allowed(p) > 1)

  		rt_rq->rt_nr_migratory++;
  
  	update_rt_migration(rt_rq);
  }
  
  static void dec_rt_migration(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
  {

  	struct task_struct *p;

  	if (!rt_entity_is_task(rt_se))
  		return;

  	p = rt_task_of(rt_se);

  	rt_rq = &rq_of_rt_rq(rt_rq)->rt;
  
  	rt_rq->rt_nr_total--;

  	if (tsk_nr_cpus_allowed(p) > 1)

  		rt_rq->rt_nr_migratory--;
  
  	update_rt_migration(rt_rq);
  }

  static inline int has_pushable_tasks(struct rq *rq)
  {
  	return !plist_head_empty(&rq->rt.pushable_tasks);
  }

  static DEFINE_PER_CPU(struct callback_head, rt_push_head);
  static DEFINE_PER_CPU(struct callback_head, rt_pull_head);

  
  static void push_rt_tasks(struct rq *);

  static void pull_rt_task(struct rq *);

  
  static inline void queue_push_tasks(struct rq *rq)

  {

  	if (!has_pushable_tasks(rq))
  		return;

  	queue_balance_callback(rq, &per_cpu(rt_push_head, rq->cpu), push_rt_tasks);
  }
  
  static inline void queue_pull_task(struct rq *rq)
  {
  	queue_balance_callback(rq, &per_cpu(rt_pull_head, rq->cpu), pull_rt_task);

  }

  static void enqueue_pushable_task(struct rq *rq, struct task_struct *p)
  {
  	plist_del(&p->pushable_tasks, &rq->rt.pushable_tasks);
  	plist_node_init(&p->pushable_tasks, p->prio);
  	plist_add(&p->pushable_tasks, &rq->rt.pushable_tasks);

  
  	/* Update the highest prio pushable task */
  	if (p->prio < rq->rt.highest_prio.next)
  		rq->rt.highest_prio.next = p->prio;

  }
  
  static void dequeue_pushable_task(struct rq *rq, struct task_struct *p)
  {
  	plist_del(&p->pushable_tasks, &rq->rt.pushable_tasks);

  	/* Update the new highest prio pushable task */
  	if (has_pushable_tasks(rq)) {
  		p = plist_first_entry(&rq->rt.pushable_tasks,
  				      struct task_struct, pushable_tasks);
  		rq->rt.highest_prio.next = p->prio;
  	} else
  		rq->rt.highest_prio.next = MAX_RT_PRIO;

  }

  #else

  static inline void enqueue_pushable_task(struct rq *rq, struct task_struct *p)

  {

  }

  static inline void dequeue_pushable_task(struct rq *rq, struct task_struct *p)
  {
  }

  static inline

  void inc_rt_migration(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
  {
  }

  static inline

  void dec_rt_migration(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
  {
  }

  static inline bool need_pull_rt_task(struct rq *rq, struct task_struct *prev)
  {
  	return false;
  }

  static inline void pull_rt_task(struct rq *this_rq)

  {

  }

  static inline void queue_push_tasks(struct rq *rq)

  {
  }

  #endif /* CONFIG_SMP */

  static void enqueue_top_rt_rq(struct rt_rq *rt_rq);
  static void dequeue_top_rt_rq(struct rt_rq *rt_rq);

  static inline int on_rt_rq(struct sched_rt_entity *rt_se)
  {

  	return rt_se->on_rq;

  }

  #ifdef CONFIG_RT_GROUP_SCHED

  static inline u64 sched_rt_runtime(struct rt_rq *rt_rq)

  {
  	if (!rt_rq->tg)

  		return RUNTIME_INF;

  	return rt_rq->rt_runtime;
  }
  
  static inline u64 sched_rt_period(struct rt_rq *rt_rq)
  {
  	return ktime_to_ns(rt_rq->tg->rt_bandwidth.rt_period);

  }

  typedef struct task_group *rt_rq_iter_t;

  static inline struct task_group *next_task_group(struct task_group *tg)
  {
  	do {
  		tg = list_entry_rcu(tg->list.next,
  			typeof(struct task_group), list);
  	} while (&tg->list != &task_groups && task_group_is_autogroup(tg));
  
  	if (&tg->list == &task_groups)
  		tg = NULL;
  
  	return tg;
  }
  
  #define for_each_rt_rq(rt_rq, iter, rq)					\
  	for (iter = container_of(&task_groups, typeof(*iter), list);	\
  		(iter = next_task_group(iter)) &&			\
  		(rt_rq = iter->rt_rq[cpu_of(rq)]);)

  #define for_each_sched_rt_entity(rt_se) \
  	for (; rt_se; rt_se = rt_se->parent)
  
  static inline struct rt_rq *group_rt_rq(struct sched_rt_entity *rt_se)
  {
  	return rt_se->my_q;
  }

  static void enqueue_rt_entity(struct sched_rt_entity *rt_se, unsigned int flags);
  static void dequeue_rt_entity(struct sched_rt_entity *rt_se, unsigned int flags);

  static void sched_rt_rq_enqueue(struct rt_rq *rt_rq)

  {

  	struct task_struct *curr = rq_of_rt_rq(rt_rq)->curr;

  	struct rq *rq = rq_of_rt_rq(rt_rq);

  	struct sched_rt_entity *rt_se;

  	int cpu = cpu_of(rq);

  
  	rt_se = rt_rq->tg->rt_se[cpu];

  	if (rt_rq->rt_nr_running) {

  		if (!rt_se)
  			enqueue_top_rt_rq(rt_rq);
  		else if (!on_rt_rq(rt_se))

  			enqueue_rt_entity(rt_se, 0);

  		if (rt_rq->highest_prio.curr < curr->prio)

  			resched_curr(rq);

  	}
  }

  static void sched_rt_rq_dequeue(struct rt_rq *rt_rq)

  {

  	struct sched_rt_entity *rt_se;

  	int cpu = cpu_of(rq_of_rt_rq(rt_rq));

  	rt_se = rt_rq->tg->rt_se[cpu];

  	if (!rt_se)
  		dequeue_top_rt_rq(rt_rq);
  	else if (on_rt_rq(rt_se))

  		dequeue_rt_entity(rt_se, 0);

  }

  static inline int rt_rq_throttled(struct rt_rq *rt_rq)
  {
  	return rt_rq->rt_throttled && !rt_rq->rt_nr_boosted;
  }

  static int rt_se_boosted(struct sched_rt_entity *rt_se)
  {
  	struct rt_rq *rt_rq = group_rt_rq(rt_se);
  	struct task_struct *p;
  
  	if (rt_rq)
  		return !!rt_rq->rt_nr_boosted;
  
  	p = rt_task_of(rt_se);
  	return p->prio != p->normal_prio;
  }

  #ifdef CONFIG_SMP

  static inline const struct cpumask *sched_rt_period_mask(void)

  {

  	return this_rq()->rd->span;

  }

  #else

  static inline const struct cpumask *sched_rt_period_mask(void)

  {

  	return cpu_online_mask;

  }
  #endif

  static inline
  struct rt_rq *sched_rt_period_rt_rq(struct rt_bandwidth *rt_b, int cpu)

  {

  	return container_of(rt_b, struct task_group, rt_bandwidth)->rt_rq[cpu];
  }

  static inline struct rt_bandwidth *sched_rt_bandwidth(struct rt_rq *rt_rq)
  {
  	return &rt_rq->tg->rt_bandwidth;
  }

  #else /* !CONFIG_RT_GROUP_SCHED */

  
  static inline u64 sched_rt_runtime(struct rt_rq *rt_rq)
  {

  	return rt_rq->rt_runtime;
  }
  
  static inline u64 sched_rt_period(struct rt_rq *rt_rq)
  {
  	return ktime_to_ns(def_rt_bandwidth.rt_period);

  }

  typedef struct rt_rq *rt_rq_iter_t;
  
  #define for_each_rt_rq(rt_rq, iter, rq) \
  	for ((void) iter, rt_rq = &rq->rt; rt_rq; rt_rq = NULL)

  #define for_each_sched_rt_entity(rt_se) \
  	for (; rt_se; rt_se = NULL)
  
  static inline struct rt_rq *group_rt_rq(struct sched_rt_entity *rt_se)
  {
  	return NULL;
  }

  static inline void sched_rt_rq_enqueue(struct rt_rq *rt_rq)

  {

  	struct rq *rq = rq_of_rt_rq(rt_rq);
  
  	if (!rt_rq->rt_nr_running)
  		return;
  
  	enqueue_top_rt_rq(rt_rq);

  	resched_curr(rq);

  }

  static inline void sched_rt_rq_dequeue(struct rt_rq *rt_rq)

  {

  	dequeue_top_rt_rq(rt_rq);

  }

  static inline int rt_rq_throttled(struct rt_rq *rt_rq)
  {
  	return rt_rq->rt_throttled;
  }

  static inline const struct cpumask *sched_rt_period_mask(void)

  {

  	return cpu_online_mask;

  }
  
  static inline
  struct rt_rq *sched_rt_period_rt_rq(struct rt_bandwidth *rt_b, int cpu)
  {
  	return &cpu_rq(cpu)->rt;
  }

  static inline struct rt_bandwidth *sched_rt_bandwidth(struct rt_rq *rt_rq)
  {
  	return &def_rt_bandwidth;
  }

  #endif /* CONFIG_RT_GROUP_SCHED */

  bool sched_rt_bandwidth_account(struct rt_rq *rt_rq)
  {
  	struct rt_bandwidth *rt_b = sched_rt_bandwidth(rt_rq);
  
  	return (hrtimer_active(&rt_b->rt_period_timer) ||
  		rt_rq->rt_time < rt_b->rt_runtime);
  }

  #ifdef CONFIG_SMP

  /*
   * We ran out of runtime, see if we can borrow some from our neighbours.
   */

  static void do_balance_runtime(struct rt_rq *rt_rq)

  {
  	struct rt_bandwidth *rt_b = sched_rt_bandwidth(rt_rq);

  	struct root_domain *rd = rq_of_rt_rq(rt_rq)->rd;

  	int i, weight;

  	u64 rt_period;

  	weight = cpumask_weight(rd->span);

  	raw_spin_lock(&rt_b->rt_runtime_lock);

  	rt_period = ktime_to_ns(rt_b->rt_period);

  	for_each_cpu(i, rd->span) {

  		struct rt_rq *iter = sched_rt_period_rt_rq(rt_b, i);
  		s64 diff;
  
  		if (iter == rt_rq)
  			continue;

  		raw_spin_lock(&iter->rt_runtime_lock);

  		/*
  		 * Either all rqs have inf runtime and there's nothing to steal
  		 * or __disable_runtime() below sets a specific rq to inf to
  		 * indicate its been disabled and disalow stealing.
  		 */

  		if (iter->rt_runtime == RUNTIME_INF)
  			goto next;

  		/*
  		 * From runqueues with spare time, take 1/n part of their
  		 * spare time, but no more than our period.
  		 */

  		diff = iter->rt_runtime - iter->rt_time;
  		if (diff > 0) {

  			diff = div_u64((u64)diff, weight);

  			if (rt_rq->rt_runtime + diff > rt_period)
  				diff = rt_period - rt_rq->rt_runtime;
  			iter->rt_runtime -= diff;
  			rt_rq->rt_runtime += diff;

  			if (rt_rq->rt_runtime == rt_period) {

  				raw_spin_unlock(&iter->rt_runtime_lock);

  				break;
  			}
  		}

  next:

  		raw_spin_unlock(&iter->rt_runtime_lock);

  	}

  	raw_spin_unlock(&rt_b->rt_runtime_lock);

  }

  /*
   * Ensure this RQ takes back all the runtime it lend to its neighbours.
   */

  static void __disable_runtime(struct rq *rq)
  {
  	struct root_domain *rd = rq->rd;

  	rt_rq_iter_t iter;

  	struct rt_rq *rt_rq;
  
  	if (unlikely(!scheduler_running))
  		return;

  	for_each_rt_rq(rt_rq, iter, rq) {

  		struct rt_bandwidth *rt_b = sched_rt_bandwidth(rt_rq);
  		s64 want;
  		int i;

  		raw_spin_lock(&rt_b->rt_runtime_lock);
  		raw_spin_lock(&rt_rq->rt_runtime_lock);

  		/*
  		 * Either we're all inf and nobody needs to borrow, or we're
  		 * already disabled and thus have nothing to do, or we have
  		 * exactly the right amount of runtime to take out.
  		 */

  		if (rt_rq->rt_runtime == RUNTIME_INF ||
  				rt_rq->rt_runtime == rt_b->rt_runtime)
  			goto balanced;

  		raw_spin_unlock(&rt_rq->rt_runtime_lock);

  		/*
  		 * Calculate the difference between what we started out with
  		 * and what we current have, that's the amount of runtime
  		 * we lend and now have to reclaim.
  		 */

  		want = rt_b->rt_runtime - rt_rq->rt_runtime;

  		/*
  		 * Greedy reclaim, take back as much as we can.
  		 */

  		for_each_cpu(i, rd->span) {

  			struct rt_rq *iter = sched_rt_period_rt_rq(rt_b, i);
  			s64 diff;

  			/*
  			 * Can't reclaim from ourselves or disabled runqueues.
  			 */

  			if (iter == rt_rq || iter->rt_runtime == RUNTIME_INF)

  				continue;

  			raw_spin_lock(&iter->rt_runtime_lock);

  			if (want > 0) {
  				diff = min_t(s64, iter->rt_runtime, want);
  				iter->rt_runtime -= diff;
  				want -= diff;
  			} else {
  				iter->rt_runtime -= want;
  				want -= want;
  			}

  			raw_spin_unlock(&iter->rt_runtime_lock);

  
  			if (!want)
  				break;
  		}

  		raw_spin_lock(&rt_rq->rt_runtime_lock);

  		/*
  		 * We cannot be left wanting - that would mean some runtime
  		 * leaked out of the system.
  		 */

  		BUG_ON(want);
  balanced:

  		/*
  		 * Disable all the borrow logic by pretending we have inf
  		 * runtime - in which case borrowing doesn't make sense.
  		 */

  		rt_rq->rt_runtime = RUNTIME_INF;

  		rt_rq->rt_throttled = 0;

  		raw_spin_unlock(&rt_rq->rt_runtime_lock);
  		raw_spin_unlock(&rt_b->rt_runtime_lock);

  
  		/* Make rt_rq available for pick_next_task() */
  		sched_rt_rq_enqueue(rt_rq);

  	}
  }

  static void __enable_runtime(struct rq *rq)
  {

  	rt_rq_iter_t iter;

  	struct rt_rq *rt_rq;
  
  	if (unlikely(!scheduler_running))
  		return;

  	/*
  	 * Reset each runqueue's bandwidth settings
  	 */

  	for_each_rt_rq(rt_rq, iter, rq) {

  		struct rt_bandwidth *rt_b = sched_rt_bandwidth(rt_rq);

  		raw_spin_lock(&rt_b->rt_runtime_lock);
  		raw_spin_lock(&rt_rq->rt_runtime_lock);

  		rt_rq->rt_runtime = rt_b->rt_runtime;
  		rt_rq->rt_time = 0;

  		rt_rq->rt_throttled = 0;

  		raw_spin_unlock(&rt_rq->rt_runtime_lock);
  		raw_spin_unlock(&rt_b->rt_runtime_lock);

  	}
  }

  static void balance_runtime(struct rt_rq *rt_rq)

  {

  	if (!sched_feat(RT_RUNTIME_SHARE))

  		return;

  	if (rt_rq->rt_time > rt_rq->rt_runtime) {

  		raw_spin_unlock(&rt_rq->rt_runtime_lock);

  		do_balance_runtime(rt_rq);

  		raw_spin_lock(&rt_rq->rt_runtime_lock);

  	}

  }

  #else /* !CONFIG_SMP */

  static inline void balance_runtime(struct rt_rq *rt_rq) {}

  #endif /* CONFIG_SMP */

  static int do_sched_rt_period_timer(struct rt_bandwidth *rt_b, int overrun)
  {

  	int i, idle = 1, throttled = 0;

  	const struct cpumask *span;

  	span = sched_rt_period_mask();

  #ifdef CONFIG_RT_GROUP_SCHED
  	/*
  	 * FIXME: isolated CPUs should really leave the root task group,
  	 * whether they are isolcpus or were isolated via cpusets, lest
  	 * the timer run on a CPU which does not service all runqueues,
  	 * potentially leaving other CPUs indefinitely throttled.  If
  	 * isolation is really required, the user will turn the throttle
  	 * off to kill the perturbations it causes anyway.  Meanwhile,
  	 * this maintains functionality for boot and/or troubleshooting.
  	 */
  	if (rt_b == &root_task_group.rt_bandwidth)
  		span = cpu_online_mask;
  #endif

  	for_each_cpu(i, span) {

  		int enqueue = 0;
  		struct rt_rq *rt_rq = sched_rt_period_rt_rq(rt_b, i);
  		struct rq *rq = rq_of_rt_rq(rt_rq);

  		raw_spin_lock(&rq->lock);

  		if (rt_rq->rt_time) {
  			u64 runtime;

  			raw_spin_lock(&rt_rq->rt_runtime_lock);

  			if (rt_rq->rt_throttled)
  				balance_runtime(rt_rq);
  			runtime = rt_rq->rt_runtime;
  			rt_rq->rt_time -= min(rt_rq->rt_time, overrun*runtime);
  			if (rt_rq->rt_throttled && rt_rq->rt_time < runtime) {
  				rt_rq->rt_throttled = 0;
  				enqueue = 1;

  
  				/*

  				 * When we're idle and a woken (rt) task is
  				 * throttled check_preempt_curr() will set
  				 * skip_update and the time between the wakeup
  				 * and this unthrottle will get accounted as
  				 * 'runtime'.

  				 */
  				if (rt_rq->rt_nr_running && rq->curr == rq->idle)

  					rq_clock_skip_update(rq, false);

  			}
  			if (rt_rq->rt_time || rt_rq->rt_nr_running)
  				idle = 0;

  			raw_spin_unlock(&rt_rq->rt_runtime_lock);

  		} else if (rt_rq->rt_nr_running) {

  			idle = 0;

  			if (!rt_rq_throttled(rt_rq))
  				enqueue = 1;
  		}

  		if (rt_rq->rt_throttled)
  			throttled = 1;

  
  		if (enqueue)
  			sched_rt_rq_enqueue(rt_rq);

  		raw_spin_unlock(&rq->lock);

  	}

  	if (!throttled && (!rt_bandwidth_enabled() || rt_b->rt_runtime == RUNTIME_INF))
  		return 1;

  	return idle;
  }

  static inline int rt_se_prio(struct sched_rt_entity *rt_se)
  {

  #ifdef CONFIG_RT_GROUP_SCHED

  	struct rt_rq *rt_rq = group_rt_rq(rt_se);
  
  	if (rt_rq)

  		return rt_rq->highest_prio.curr;

  #endif
  
  	return rt_task_of(rt_se)->prio;
  }

  static int sched_rt_runtime_exceeded(struct rt_rq *rt_rq)

  {

  	u64 runtime = sched_rt_runtime(rt_rq);

  	if (rt_rq->rt_throttled)

  		return rt_rq_throttled(rt_rq);

  	if (runtime >= sched_rt_period(rt_rq))

  		return 0;

  	balance_runtime(rt_rq);
  	runtime = sched_rt_runtime(rt_rq);
  	if (runtime == RUNTIME_INF)
  		return 0;

  	if (rt_rq->rt_time > runtime) {

  		struct rt_bandwidth *rt_b = sched_rt_bandwidth(rt_rq);
  
  		/*
  		 * Don't actually throttle groups that have no runtime assigned
  		 * but accrue some time due to boosting.
  		 */
  		if (likely(rt_b->rt_runtime)) {
  			rt_rq->rt_throttled = 1;

  			printk_deferred_once("sched: RT throttling activated
  ");

  		} else {
  			/*
  			 * In case we did anyway, make it go away,
  			 * replenishment is a joke, since it will replenish us
  			 * with exactly 0 ns.
  			 */
  			rt_rq->rt_time = 0;
  		}

  		if (rt_rq_throttled(rt_rq)) {

  			sched_rt_rq_dequeue(rt_rq);

  			return 1;
  		}

  	}
  
  	return 0;
  }

  /*
   * Update the current task's runtime statistics. Skip current tasks that
   * are not in our scheduling class.
   */

  static void update_curr_rt(struct rq *rq)

  {
  	struct task_struct *curr = rq->curr;

  	struct sched_rt_entity *rt_se = &curr->rt;

  	u64 delta_exec;

  	if (curr->sched_class != &rt_sched_class)

  		return;

  	delta_exec = rq_clock_task(rq) - curr->se.exec_start;

  	if (unlikely((s64)delta_exec <= 0))
  		return;

  	/* Kick cpufreq (see the comment in kernel/sched/sched.h). */

  	cpufreq_update_this_cpu(rq, SCHED_CPUFREQ_RT);

  	schedstat_set(curr->se.statistics.exec_max,
  		      max(curr->se.statistics.exec_max, delta_exec));

  
  	curr->se.sum_exec_runtime += delta_exec;

  	account_group_exec_runtime(curr, delta_exec);

  	curr->se.exec_start = rq_clock_task(rq);

  	cpuacct_charge(curr, delta_exec);

  	sched_rt_avg_update(rq, delta_exec);

  	if (!rt_bandwidth_enabled())
  		return;

  	for_each_sched_rt_entity(rt_se) {

  		struct rt_rq *rt_rq = rt_rq_of_se(rt_se);

  		if (sched_rt_runtime(rt_rq) != RUNTIME_INF) {

  			raw_spin_lock(&rt_rq->rt_runtime_lock);

  			rt_rq->rt_time += delta_exec;
  			if (sched_rt_runtime_exceeded(rt_rq))

  				resched_curr(rq);

  			raw_spin_unlock(&rt_rq->rt_runtime_lock);

  		}

  	}

  }

  static void
  dequeue_top_rt_rq(struct rt_rq *rt_rq)
  {
  	struct rq *rq = rq_of_rt_rq(rt_rq);
  
  	BUG_ON(&rq->rt != rt_rq);
  
  	if (!rt_rq->rt_queued)
  		return;
  
  	BUG_ON(!rq->nr_running);

  	sub_nr_running(rq, rt_rq->rt_nr_running);

  	rt_rq->rt_queued = 0;
  }
  
  static void
  enqueue_top_rt_rq(struct rt_rq *rt_rq)
  {
  	struct rq *rq = rq_of_rt_rq(rt_rq);
  
  	BUG_ON(&rq->rt != rt_rq);
  
  	if (rt_rq->rt_queued)
  		return;
  	if (rt_rq_throttled(rt_rq) || !rt_rq->rt_nr_running)
  		return;

  	add_nr_running(rq, rt_rq->rt_nr_running);

  	rt_rq->rt_queued = 1;
  }

  #if defined CONFIG_SMP

  static void
  inc_rt_prio_smp(struct rt_rq *rt_rq, int prio, int prev_prio)

  {

  	struct rq *rq = rq_of_rt_rq(rt_rq);

  #ifdef CONFIG_RT_GROUP_SCHED
  	/*
  	 * Change rq's cpupri only if rt_rq is the top queue.
  	 */
  	if (&rq->rt != rt_rq)
  		return;
  #endif

  	if (rq->online && prio < prev_prio)
  		cpupri_set(&rq->rd->cpupri, rq->cpu, prio);

  }

  static void
  dec_rt_prio_smp(struct rt_rq *rt_rq, int prio, int prev_prio)
  {
  	struct rq *rq = rq_of_rt_rq(rt_rq);

  #ifdef CONFIG_RT_GROUP_SCHED
  	/*
  	 * Change rq's cpupri only if rt_rq is the top queue.
  	 */
  	if (&rq->rt != rt_rq)
  		return;
  #endif

  	if (rq->online && rt_rq->highest_prio.curr != prev_prio)
  		cpupri_set(&rq->rd->cpupri, rq->cpu, rt_rq->highest_prio.curr);

  }

  #else /* CONFIG_SMP */

  static inline

  void inc_rt_prio_smp(struct rt_rq *rt_rq, int prio, int prev_prio) {}
  static inline
  void dec_rt_prio_smp(struct rt_rq *rt_rq, int prio, int prev_prio) {}
  
  #endif /* CONFIG_SMP */

  #if defined CONFIG_SMP || defined CONFIG_RT_GROUP_SCHED

  static void
  inc_rt_prio(struct rt_rq *rt_rq, int prio)
  {
  	int prev_prio = rt_rq->highest_prio.curr;
  
  	if (prio < prev_prio)
  		rt_rq->highest_prio.curr = prio;
  
  	inc_rt_prio_smp(rt_rq, prio, prev_prio);
  }
  
  static void
  dec_rt_prio(struct rt_rq *rt_rq, int prio)
  {
  	int prev_prio = rt_rq->highest_prio.curr;

  	if (rt_rq->rt_nr_running) {

  		WARN_ON(prio < prev_prio);

  		/*

  		 * This may have been our highest task, and therefore
  		 * we may have some recomputation to do

  		 */

  		if (prio == prev_prio) {

  			struct rt_prio_array *array = &rt_rq->active;
  
  			rt_rq->highest_prio.curr =

  				sched_find_first_bit(array->bitmap);

  		}

  	} else

  		rt_rq->highest_prio.curr = MAX_RT_PRIO;

  	dec_rt_prio_smp(rt_rq, prio, prev_prio);
  }

  #else
  
  static inline void inc_rt_prio(struct rt_rq *rt_rq, int prio) {}
  static inline void dec_rt_prio(struct rt_rq *rt_rq, int prio) {}
  
  #endif /* CONFIG_SMP || CONFIG_RT_GROUP_SCHED */

  #ifdef CONFIG_RT_GROUP_SCHED

  
  static void
  inc_rt_group(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
  {
  	if (rt_se_boosted(rt_se))
  		rt_rq->rt_nr_boosted++;
  
  	if (rt_rq->tg)
  		start_rt_bandwidth(&rt_rq->tg->rt_bandwidth);
  }
  
  static void
  dec_rt_group(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
  {

  	if (rt_se_boosted(rt_se))
  		rt_rq->rt_nr_boosted--;
  
  	WARN_ON(!rt_rq->rt_nr_running && rt_rq->rt_nr_boosted);

  }
  
  #else /* CONFIG_RT_GROUP_SCHED */
  
  static void
  inc_rt_group(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
  {
  	start_rt_bandwidth(&def_rt_bandwidth);
  }
  
  static inline
  void dec_rt_group(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq) {}
  
  #endif /* CONFIG_RT_GROUP_SCHED */
  
  static inline

  unsigned int rt_se_nr_running(struct sched_rt_entity *rt_se)
  {
  	struct rt_rq *group_rq = group_rt_rq(rt_se);
  
  	if (group_rq)
  		return group_rq->rt_nr_running;
  	else
  		return 1;
  }
  
  static inline

  unsigned int rt_se_rr_nr_running(struct sched_rt_entity *rt_se)
  {
  	struct rt_rq *group_rq = group_rt_rq(rt_se);
  	struct task_struct *tsk;
  
  	if (group_rq)
  		return group_rq->rr_nr_running;
  
  	tsk = rt_task_of(rt_se);
  
  	return (tsk->policy == SCHED_RR) ? 1 : 0;
  }
  
  static inline

  void inc_rt_tasks(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
  {
  	int prio = rt_se_prio(rt_se);
  
  	WARN_ON(!rt_prio(prio));

  	rt_rq->rt_nr_running += rt_se_nr_running(rt_se);

  	rt_rq->rr_nr_running += rt_se_rr_nr_running(rt_se);

  
  	inc_rt_prio(rt_rq, prio);
  	inc_rt_migration(rt_se, rt_rq);
  	inc_rt_group(rt_se, rt_rq);
  }
  
  static inline
  void dec_rt_tasks(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
  {
  	WARN_ON(!rt_prio(rt_se_prio(rt_se)));
  	WARN_ON(!rt_rq->rt_nr_running);

  	rt_rq->rt_nr_running -= rt_se_nr_running(rt_se);

  	rt_rq->rr_nr_running -= rt_se_rr_nr_running(rt_se);

  
  	dec_rt_prio(rt_rq, rt_se_prio(rt_se));
  	dec_rt_migration(rt_se, rt_rq);
  	dec_rt_group(rt_se, rt_rq);

  }

  /*
   * Change rt_se->run_list location unless SAVE && !MOVE
   *
   * assumes ENQUEUE/DEQUEUE flags match
   */
  static inline bool move_entity(unsigned int flags)
  {
  	if ((flags & (DEQUEUE_SAVE | DEQUEUE_MOVE)) == DEQUEUE_SAVE)
  		return false;
  
  	return true;
  }
  
  static void __delist_rt_entity(struct sched_rt_entity *rt_se, struct rt_prio_array *array)
  {
  	list_del_init(&rt_se->run_list);
  
  	if (list_empty(array->queue + rt_se_prio(rt_se)))
  		__clear_bit(rt_se_prio(rt_se), array->bitmap);
  
  	rt_se->on_list = 0;
  }
  
  static void __enqueue_rt_entity(struct sched_rt_entity *rt_se, unsigned int flags)

  {

  	struct rt_rq *rt_rq = rt_rq_of_se(rt_se);
  	struct rt_prio_array *array = &rt_rq->active;
  	struct rt_rq *group_rq = group_rt_rq(rt_se);

  	struct list_head *queue = array->queue + rt_se_prio(rt_se);

  	/*
  	 * Don't enqueue the group if its throttled, or when empty.
  	 * The latter is a consequence of the former when a child group
  	 * get throttled and the current group doesn't have any other
  	 * active members.
  	 */

  	if (group_rq && (rt_rq_throttled(group_rq) || !group_rq->rt_nr_running)) {
  		if (rt_se->on_list)
  			__delist_rt_entity(rt_se, array);

  		return;

  	}

  	if (move_entity(flags)) {
  		WARN_ON_ONCE(rt_se->on_list);
  		if (flags & ENQUEUE_HEAD)
  			list_add(&rt_se->run_list, queue);
  		else
  			list_add_tail(&rt_se->run_list, queue);
  
  		__set_bit(rt_se_prio(rt_se), array->bitmap);
  		rt_se->on_list = 1;
  	}
  	rt_se->on_rq = 1;

  	inc_rt_tasks(rt_se, rt_rq);
  }

  static void __dequeue_rt_entity(struct sched_rt_entity *rt_se, unsigned int flags)

  {
  	struct rt_rq *rt_rq = rt_rq_of_se(rt_se);
  	struct rt_prio_array *array = &rt_rq->active;

  	if (move_entity(flags)) {
  		WARN_ON_ONCE(!rt_se->on_list);
  		__delist_rt_entity(rt_se, array);
  	}
  	rt_se->on_rq = 0;

  
  	dec_rt_tasks(rt_se, rt_rq);
  }
  
  /*
   * Because the prio of an upper entry depends on the lower
   * entries, we must remove entries top - down.

   */

  static void dequeue_rt_stack(struct sched_rt_entity *rt_se, unsigned int flags)

  {

  	struct sched_rt_entity *back = NULL;

  	for_each_sched_rt_entity(rt_se) {
  		rt_se->back = back;
  		back = rt_se;
  	}

  	dequeue_top_rt_rq(rt_rq_of_se(back));

  	for (rt_se = back; rt_se; rt_se = rt_se->back) {
  		if (on_rt_rq(rt_se))

  			__dequeue_rt_entity(rt_se, flags);

  	}
  }

  static void enqueue_rt_entity(struct sched_rt_entity *rt_se, unsigned int flags)

  {

  	struct rq *rq = rq_of_rt_se(rt_se);

  	dequeue_rt_stack(rt_se, flags);

  	for_each_sched_rt_entity(rt_se)

  		__enqueue_rt_entity(rt_se, flags);

  	enqueue_top_rt_rq(&rq->rt);

  }

  static void dequeue_rt_entity(struct sched_rt_entity *rt_se, unsigned int flags)

  {

  	struct rq *rq = rq_of_rt_se(rt_se);

  	dequeue_rt_stack(rt_se, flags);

  
  	for_each_sched_rt_entity(rt_se) {
  		struct rt_rq *rt_rq = group_rt_rq(rt_se);
  
  		if (rt_rq && rt_rq->rt_nr_running)

  			__enqueue_rt_entity(rt_se, flags);

  	}

  	enqueue_top_rt_rq(&rq->rt);

  }
  
  /*
   * Adding/removing a task to/from a priority array:
   */

  static void

  enqueue_task_rt(struct rq *rq, struct task_struct *p, int flags)

  {
  	struct sched_rt_entity *rt_se = &p->rt;

  	if (flags & ENQUEUE_WAKEUP)

  		rt_se->timeout = 0;

  	enqueue_rt_entity(rt_se, flags);

  	if (!task_current(rq, p) && tsk_nr_cpus_allowed(p) > 1)

  		enqueue_pushable_task(rq, p);

  }

  static void dequeue_task_rt(struct rq *rq, struct task_struct *p, int flags)

  {

  	struct sched_rt_entity *rt_se = &p->rt;

  	update_curr_rt(rq);

  	dequeue_rt_entity(rt_se, flags);

  	dequeue_pushable_task(rq, p);

  }
  
  /*

   * Put task to the head or the end of the run list without the overhead of
   * dequeue followed by enqueue.

   */

  static void
  requeue_rt_entity(struct rt_rq *rt_rq, struct sched_rt_entity *rt_se, int head)

  {

  	if (on_rt_rq(rt_se)) {

  		struct rt_prio_array *array = &rt_rq->active;
  		struct list_head *queue = array->queue + rt_se_prio(rt_se);
  
  		if (head)
  			list_move(&rt_se->run_list, queue);
  		else
  			list_move_tail(&rt_se->run_list, queue);

  	}

  }

  static void requeue_task_rt(struct rq *rq, struct task_struct *p, int head)

  {

  	struct sched_rt_entity *rt_se = &p->rt;
  	struct rt_rq *rt_rq;

  	for_each_sched_rt_entity(rt_se) {
  		rt_rq = rt_rq_of_se(rt_se);

  		requeue_rt_entity(rt_rq, rt_se, head);

  	}

  }

  static void yield_task_rt(struct rq *rq)

  {

  	requeue_task_rt(rq, rq->curr, 0);

  }

  #ifdef CONFIG_SMP

  static int find_lowest_rq(struct task_struct *task);

  static int

  select_task_rq_rt(struct task_struct *p, int cpu, int sd_flag, int flags)

  {

  	struct task_struct *curr;
  	struct rq *rq;

  
  	/* For anything but wake ups, just return the task_cpu */
  	if (sd_flag != SD_BALANCE_WAKE && sd_flag != SD_BALANCE_FORK)
  		goto out;

  	rq = cpu_rq(cpu);
  
  	rcu_read_lock();

  	curr = READ_ONCE(rq->curr); /* unlocked access */

  	/*

  	 * If the current task on @p's runqueue is an RT task, then

  	 * try to see if we can wake this RT task up on another
  	 * runqueue. Otherwise simply start this RT task
  	 * on its current runqueue.
  	 *

  	 * We want to avoid overloading runqueues. If the woken
  	 * task is a higher priority, then it will stay on this CPU
  	 * and the lower prio task should be moved to another CPU.
  	 * Even though this will probably make the lower prio task
  	 * lose its cache, we do not want to bounce a higher task
  	 * around just because it gave up its CPU, perhaps for a
  	 * lock?
  	 *
  	 * For equal prio tasks, we just let the scheduler sort it out.

  	 *
  	 * Otherwise, just let it ride on the affined RQ and the
  	 * post-schedule router will push the preempted task away
  	 *
  	 * This test is optimistic, if we get it wrong the load-balancer
  	 * will have to sort it out.

  	 */

  	if (curr && unlikely(rt_task(curr)) &&

  	    (tsk_nr_cpus_allowed(curr) < 2 ||

  	     curr->prio <= p->prio)) {

  		int target = find_lowest_rq(p);

  		/*
  		 * Don't bother moving it if the destination CPU is
  		 * not running a lower priority task.
  		 */
  		if (target != -1 &&
  		    p->prio < cpu_rq(target)->rt.highest_prio.curr)

  			cpu = target;

  	}

  	rcu_read_unlock();

  out:

  	return cpu;

  }

  
  static void check_preempt_equal_prio(struct rq *rq, struct task_struct *p)
  {

  	/*
  	 * Current can't be migrated, useless to reschedule,
  	 * let's hope p can move out.
  	 */

  	if (tsk_nr_cpus_allowed(rq->curr) == 1 ||

  	    !cpupri_find(&rq->rd->cpupri, rq->curr, NULL))

  		return;

  	/*
  	 * p is migratable, so let's not schedule it and
  	 * see if it is pushed or pulled somewhere else.
  	 */

  	if (tsk_nr_cpus_allowed(p) != 1

  	    && cpupri_find(&rq->rd->cpupri, p, NULL))
  		return;

  	/*
  	 * There appears to be other cpus that can accept
  	 * current and none to run 'p', so lets reschedule
  	 * to try and push current away:
  	 */
  	requeue_task_rt(rq, p, 1);

  	resched_curr(rq);

  }

  #endif /* CONFIG_SMP */

  /*
   * Preempt the current task with a newly woken task if needed:
   */

  static void check_preempt_curr_rt(struct rq *rq, struct task_struct *p, int flags)

  {

  	if (p->prio < rq->curr->prio) {

  		resched_curr(rq);

  		return;
  	}
  
  #ifdef CONFIG_SMP
  	/*
  	 * If:
  	 *
  	 * - the newly woken task is of equal priority to the current task
  	 * - the newly woken task is non-migratable while current is migratable
  	 * - current will be preempted on the next reschedule
  	 *
  	 * we should check to see if current can readily move to a different
  	 * cpu.  If so, we will reschedule to allow the push logic to try
  	 * to move current somewhere else, making room for our non-migratable
  	 * task.
  	 */

  	if (p->prio == rq->curr->prio && !test_tsk_need_resched(rq->curr))

  		check_preempt_equal_prio(rq, p);

  #endif

  }

  static struct sched_rt_entity *pick_next_rt_entity(struct rq *rq,
  						   struct rt_rq *rt_rq)

  {

  	struct rt_prio_array *array = &rt_rq->active;
  	struct sched_rt_entity *next = NULL;

  	struct list_head *queue;
  	int idx;
  
  	idx = sched_find_first_bit(array->bitmap);

  	BUG_ON(idx >= MAX_RT_PRIO);

  
  	queue = array->queue + idx;

  	next = list_entry(queue->next, struct sched_rt_entity, run_list);

  	return next;
  }

  static struct task_struct *_pick_next_task_rt(struct rq *rq)

  {
  	struct sched_rt_entity *rt_se;
  	struct task_struct *p;

  	struct rt_rq *rt_rq  = &rq->rt;

  
  	do {
  		rt_se = pick_next_rt_entity(rq, rt_rq);

  		BUG_ON(!rt_se);

  		rt_rq = group_rt_rq(rt_se);
  	} while (rt_rq);
  
  	p = rt_task_of(rt_se);

  	p->se.exec_start = rq_clock_task(rq);

  
  	return p;
  }

  static struct task_struct *

  pick_next_task_rt(struct rq *rq, struct task_struct *prev, struct pin_cookie cookie)

  {

  	struct task_struct *p;
  	struct rt_rq *rt_rq = &rq->rt;

  	if (need_pull_rt_task(rq, prev)) {

  		/*
  		 * This is OK, because current is on_cpu, which avoids it being
  		 * picked for load-balance and preemption/IRQs are still
  		 * disabled avoiding further scheduler activity on it and we're
  		 * being very careful to re-start the picking loop.
  		 */

  		lockdep_unpin_lock(&rq->lock, cookie);

  		pull_rt_task(rq);

  		lockdep_repin_lock(&rq->lock, cookie);

  		/*
  		 * pull_rt_task() can drop (and re-acquire) rq->lock; this

  		 * means a dl or stop task can slip in, in which case we need
  		 * to re-start task selection.

  		 */

  		if (unlikely((rq->stop && task_on_rq_queued(rq->stop)) ||

  			     rq->dl.dl_nr_running))

  			return RETRY_TASK;
  	}

  	/*
  	 * We may dequeue prev's rt_rq in put_prev_task().
  	 * So, we update time before rt_nr_running check.
  	 */
  	if (prev->sched_class == &rt_sched_class)
  		update_curr_rt(rq);

  	if (!rt_rq->rt_queued)

  		return NULL;

  	put_prev_task(rq, prev);

  
  	p = _pick_next_task_rt(rq);

  
  	/* The running task is never eligible for pushing */

  	dequeue_pushable_task(rq, p);

  	queue_push_tasks(rq);

  	return p;

  }

  static void put_prev_task_rt(struct rq *rq, struct task_struct *p)

  {

  	update_curr_rt(rq);

  
  	/*
  	 * The previous task needs to be made eligible for pushing
  	 * if it is still active
  	 */

  	if (on_rt_rq(&p->rt) && tsk_nr_cpus_allowed(p) > 1)

  		enqueue_pushable_task(rq, p);

  }

  #ifdef CONFIG_SMP

  /* Only try algorithms three times */
  #define RT_MAX_TRIES 3

  static int pick_rt_task(struct rq *rq, struct task_struct *p, int cpu)
  {
  	if (!task_running(rq, p) &&

  	    cpumask_test_cpu(cpu, tsk_cpus_allowed(p)))

  		return 1;
  	return 0;
  }

  /*
   * Return the highest pushable rq's task, which is suitable to be executed
   * on the cpu, NULL otherwise
   */
  static struct task_struct *pick_highest_pushable_task(struct rq *rq, int cpu)

  {

  	struct plist_head *head = &rq->rt.pushable_tasks;
  	struct task_struct *p;

  	if (!has_pushable_tasks(rq))
  		return NULL;

  	plist_for_each_entry(p, head, pushable_tasks) {
  		if (pick_rt_task(rq, p, cpu))
  			return p;

  	}

  	return NULL;

  }

  static DEFINE_PER_CPU(cpumask_var_t, local_cpu_mask);

  static int find_lowest_rq(struct task_struct *task)
  {
  	struct sched_domain *sd;

  	struct cpumask *lowest_mask = this_cpu_cpumask_var_ptr(local_cpu_mask);

  	int this_cpu = smp_processor_id();
  	int cpu      = task_cpu(task);

  	/* Make sure the mask is initialized first */
  	if (unlikely(!lowest_mask))
  		return -1;

  	if (tsk_nr_cpus_allowed(task) == 1)

  		return -1; /* No other targets possible */