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	Version: linux-6.0.1 spark-3.0.0 hadoop-3.2.0-src hadoop-3.3.0-src spark-2.4.7 linux-4.15.13 hadoop-2.7.4-src Revert   Change

 // SPDX-License-Identifier: GPL-2.0
 /*
  * Real-Time Scheduling Class (mapped to the SCHED_FIFO and SCHED_RR
  * policies)
  */
 
 int sched_rr_timeslice = RR_TIMESLICE;
 /* More than 4 hours if BW_SHIFT equals 20. */
 static const u64 max_rt_runtime = MAX_BW;
 
 static int do_sched_rt_period_timer(struct rt_bandwidth *rt_b, int overrun);
 
 struct rt_bandwidth def_rt_bandwidth;
 
 /*
  * period over which we measure -rt task CPU usage in us.
  * default: 1s
  */
 unsigned int sysctl_sched_rt_period = 1000000;
 
 /*
  * part of the period that we allow rt tasks to run in us.
  * default: 0.95s
  */
 int sysctl_sched_rt_runtime = 950000;
 
 #ifdef CONFIG_SYSCTL
 static int sysctl_sched_rr_timeslice = (MSEC_PER_SEC / HZ) * RR_TIMESLICE;
 static int sched_rt_handler(struct ctl_table *table, int write, void *buffer,
         size_t *lenp, loff_t *ppos);
 static int sched_rr_handler(struct ctl_table *table, int write, void *buffer,
         size_t *lenp, loff_t *ppos);
 static struct ctl_table sched_rt_sysctls[] = {
     {
         .procname       = "sched_rt_period_us",
         .data           = &sysctl_sched_rt_period,
         .maxlen         = sizeof(unsigned int),
         .mode           = 0644,
         .proc_handler   = sched_rt_handler,
     },
     {
         .procname       = "sched_rt_runtime_us",
         .data           = &sysctl_sched_rt_runtime,
         .maxlen         = sizeof(int),
         .mode           = 0644,
         .proc_handler   = sched_rt_handler,
     },
     {
         .procname       = "sched_rr_timeslice_ms",
         .data           = &sysctl_sched_rr_timeslice,
         .maxlen         = sizeof(int),
         .mode           = 0644,
         .proc_handler   = sched_rr_handler,
     },
     {}
 };
 
 static int __init sched_rt_sysctl_init(void)
 {
     register_sysctl_init("kernel", sched_rt_sysctls);
     return 0;
 }
 late_initcall(sched_rt_sysctl_init);
 #endif
 
 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_HARD);
     rt_b->rt_period_timer.function = sched_rt_period_timer;
 }
 
 static inline void do_start_rt_bandwidth(struct rt_bandwidth *rt_b)
 {
     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_HARD);
     }
     raw_spin_unlock(&rt_b->rt_runtime_lock);
 }
 
 static void start_rt_bandwidth(struct rt_bandwidth *rt_b)
 {
     if (!rt_bandwidth_enabled() || rt_b->rt_runtime == RUNTIME_INF)
         return;
 
     do_start_rt_bandwidth(rt_b);
 }
 
 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-1;
     rt_rq->highest_prio.next = MAX_RT_PRIO-1;
     rt_rq->rt_nr_migratory = 0;
     rt_rq->overloaded = 0;
     plist_head_init(&rt_rq->pushable_tasks);
 #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 unregister_rt_sched_group(struct task_group *tg)
 {
     if (tg->rt_se)
         destroy_rt_bandwidth(&tg->rt_bandwidth);
 
 }
 
 void free_rt_sched_group(struct task_group *tg)
 {
     int i;
 
     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-1;
     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 = kcalloc(nr_cpu_ids, sizeof(rt_rq), GFP_KERNEL);
     if (!tg->rt_rq)
         goto err;
     tg->rt_se = kcalloc(nr_cpu_ids, sizeof(rt_se), 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 unregister_rt_sched_group(struct task_group *tg) { }
 
 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 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->online && 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 (p->nr_cpus_allowed > 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 (p->nr_cpus_allowed > 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 rt_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 rt_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-1;
     }
 }
 
 #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 void rt_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, unsigned int count);
 
 static inline int on_rt_rq(struct sched_rt_entity *rt_se)
 {
     return rt_se->on_rq;
 }
 
 #ifdef CONFIG_UCLAMP_TASK
 /*
  * Verify the fitness of task @p to run on @cpu taking into account the uclamp
  * settings.
  *
  * This check is only important for heterogeneous systems where uclamp_min value
  * is higher than the capacity of a @cpu. For non-heterogeneous system this
  * function will always return true.
  *
  * The function will return true if the capacity of the @cpu is >= the
  * uclamp_min and false otherwise.
  *
  * Note that uclamp_min will be clamped to uclamp_max if uclamp_min
  * > uclamp_max.
  */
 static inline bool rt_task_fits_capacity(struct task_struct *p, int cpu)
 {
     unsigned int min_cap;
     unsigned int max_cap;
     unsigned int cpu_cap;
 
     /* Only heterogeneous systems can benefit from this check */
     if (!static_branch_unlikely(&sched_asym_cpucapacity))
         return true;
 
     min_cap = uclamp_eff_value(p, UCLAMP_MIN);
     max_cap = uclamp_eff_value(p, UCLAMP_MAX);
 
     cpu_cap = capacity_orig_of(cpu);
 
     return cpu_cap >= min(min_cap, max_cap);
 }
 #else
 static inline bool rt_task_fits_capacity(struct task_struct *p, int cpu)
 {
     return true;
 }
 #endif
 
 #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, rt_rq->rt_nr_running);
         /* Kick cpufreq (see the comment in kernel/sched/sched.h). */
         cpufreq_update_util(rq_of_rt_rq(rt_rq), 0);
     }
     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, rt_rq->rt_nr_running);
 }
 
 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 disallow 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);
         struct rq_flags rf;
         int skip;
 
         /*
          * When span == cpu_online_mask, taking each rq->lock
          * can be time-consuming. Try to avoid it when possible.
          */
         raw_spin_lock(&rt_rq->rt_runtime_lock);
         if (!sched_feat(RT_RUNTIME_SHARE) && rt_rq->rt_runtime != RUNTIME_INF)
             rt_rq->rt_runtime = rt_b->rt_runtime;
         skip = !rt_rq->rt_time && !rt_rq->rt_nr_running;
         raw_spin_unlock(&rt_rq->rt_runtime_lock);
         if (skip)
             continue;
 
         rq_lock(rq, &rf);
         update_rq_clock(rq);
 
         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_cancel_skipupdate(rq);
             }
             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);
         rq_unlock(rq, &rf);
     }
 
     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\n");
         } 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;
     u64 now;
 
     if (curr->sched_class != &rt_sched_class)
         return;
 
     now = rq_clock_task(rq);
     delta_exec = now - curr->se.exec_start;
     if (unlikely((s64)delta_exec <= 0))
         return;
 
     schedstat_set(curr->stats.exec_max,
               max(curr->stats.exec_max, delta_exec));
 
     trace_sched_stat_runtime(curr, delta_exec, 0);
 
     curr->se.sum_exec_runtime += delta_exec;
     account_group_exec_runtime(curr, delta_exec);
 
     curr->se.exec_start = now;
     cgroup_account_cputime(curr, 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);
         int exceeded;
 
         if (sched_rt_runtime(rt_rq) != RUNTIME_INF) {
             raw_spin_lock(&rt_rq->rt_runtime_lock);
             rt_rq->rt_time += delta_exec;
             exceeded = sched_rt_runtime_exceeded(rt_rq);
             if (exceeded)
                 resched_curr(rq);
             raw_spin_unlock(&rt_rq->rt_runtime_lock);
             if (exceeded)
                 do_start_rt_bandwidth(sched_rt_bandwidth(rt_rq));
         }
     }
 }
 
 static void
 dequeue_top_rt_rq(struct rt_rq *rt_rq, unsigned int count)
 {
     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, count);
     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))
         return;
 
     if (rt_rq->rt_nr_running) {
         add_nr_running(rq, rt_rq->rt_nr_running);
         rt_rq->rt_queued = 1;
     }
 
     /* Kick cpufreq (see the comment in kernel/sched/sched.h). */
     cpufreq_update_util(rq, 0);
 }
 
 #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-1;
     }
 
     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 inline struct sched_statistics *
 __schedstats_from_rt_se(struct sched_rt_entity *rt_se)
 {
 #ifdef CONFIG_RT_GROUP_SCHED
     /* schedstats is not supported for rt group. */
     if (!rt_entity_is_task(rt_se))
         return NULL;
 #endif
 
     return &rt_task_of(rt_se)->stats;
 }
 
 static inline void
 update_stats_wait_start_rt(struct rt_rq *rt_rq, struct sched_rt_entity *rt_se)
 {
     struct sched_statistics *stats;
     struct task_struct *p = NULL;
 
     if (!schedstat_enabled())
         return;
 
     if (rt_entity_is_task(rt_se))
         p = rt_task_of(rt_se);
 
     stats = __schedstats_from_rt_se(rt_se);
     if (!stats)
         return;
 
     __update_stats_wait_start(rq_of_rt_rq(rt_rq), p, stats);
 }
 
 static inline void
 update_stats_enqueue_sleeper_rt(struct rt_rq *rt_rq, struct sched_rt_entity *rt_se)
 {
     struct sched_statistics *stats;
     struct task_struct *p = NULL;
 
     if (!schedstat_enabled())
         return;
 
     if (rt_entity_is_task(rt_se))
         p = rt_task_of(rt_se);
 
     stats = __schedstats_from_rt_se(rt_se);
     if (!stats)
         return;
 
     __update_stats_enqueue_sleeper(rq_of_rt_rq(rt_rq), p, stats);
 }
 
 static inline void
 update_stats_enqueue_rt(struct rt_rq *rt_rq, struct sched_rt_entity *rt_se,
             int flags)
 {
     if (!schedstat_enabled())
         return;
 
     if (flags & ENQUEUE_WAKEUP)
         update_stats_enqueue_sleeper_rt(rt_rq, rt_se);
 }
 
 static inline void
 update_stats_wait_end_rt(struct rt_rq *rt_rq, struct sched_rt_entity *rt_se)
 {
     struct sched_statistics *stats;
     struct task_struct *p = NULL;
 
     if (!schedstat_enabled())
         return;
 
     if (rt_entity_is_task(rt_se))
         p = rt_task_of(rt_se);
 
     stats = __schedstats_from_rt_se(rt_se);
     if (!stats)
         return;
 
     __update_stats_wait_end(rq_of_rt_rq(rt_rq), p, stats);
 }
 
 static inline void
 update_stats_dequeue_rt(struct rt_rq *rt_rq, struct sched_rt_entity *rt_se,
             int flags)
 {
     struct task_struct *p = NULL;
 
     if (!schedstat_enabled())
         return;
 
     if (rt_entity_is_task(rt_se))
         p = rt_task_of(rt_se);
 
     if ((flags & DEQUEUE_SLEEP) && p) {
         unsigned int state;
 
         state = READ_ONCE(p->__state);
         if (state & TASK_INTERRUPTIBLE)
             __schedstat_set(p->stats.sleep_start,
                     rq_clock(rq_of_rt_rq(rt_rq)));
 
         if (state & TASK_UNINTERRUPTIBLE)
             __schedstat_set(p->stats.block_start,
                     rq_clock(rq_of_rt_rq(rt_rq)));
     }
 }
 
 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;
     unsigned int rt_nr_running;
 
     for_each_sched_rt_entity(rt_se) {
         rt_se->back = back;
         back = rt_se;
     }
 
     rt_nr_running = rt_rq_of_se(back)->rt_nr_running;
 
     for (rt_se = back; rt_se; rt_se = rt_se->back) {
         if (on_rt_rq(rt_se))
             __dequeue_rt_entity(rt_se, flags);
     }
 
     dequeue_top_rt_rq(rt_rq_of_se(back), rt_nr_running);
 }
 
 static void enqueue_rt_entity(struct sched_rt_entity *rt_se, unsigned int flags)
 {
     struct rq *rq = rq_of_rt_se(rt_se);
 
     update_stats_enqueue_rt(rt_rq_of_se(rt_se), rt_se, flags);
 
     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);
 
     update_stats_dequeue_rt(rt_rq_of_se(rt_se), rt_se, flags);
 
     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;
 
     check_schedstat_required();
     update_stats_wait_start_rt(rt_rq_of_se(rt_se), rt_se);
 
     enqueue_rt_entity(rt_se, flags);
 
     if (!task_current(rq, p) && p->nr_cpus_allowed > 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 flags)
 {
     struct task_struct *curr;
     struct rq *rq;
     bool test;
 
     /* For anything but wake ups, just return the task_cpu */
     if (!(flags & (WF_TTWU | WF_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.
      *
      * We take into account the capacity of the CPU to ensure it fits the
      * requirement of the task - which is only important on heterogeneous
      * systems like big.LITTLE.
      */
     test = curr &&
            unlikely(rt_task(curr)) &&
            (curr->nr_cpus_allowed < 2 || curr->prio <= p->prio);
 
     if (test || !rt_task_fits_capacity(p, cpu)) {
         int target = find_lowest_rq(p);
 
         /*
          * Bail out if we were forcing a migration to find a better
          * fitting CPU but our search failed.
          */
         if (!test && target != -1 && !rt_task_fits_capacity(p, target))
             goto out_unlock;
 
         /*
          * 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;
     }
 
 out_unlock:
     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 (rq->curr->nr_cpus_allowed == 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 (p->nr_cpus_allowed != 1 &&
         cpupri_find(&rq->rd->cpupri, p, NULL))
         return;
 
     /*
      * There appear to be other CPUs that can accept
      * the current task but none can run 'p', so lets reschedule
      * to try and push the current task away:
      */
     requeue_task_rt(rq, p, 1);
     resched_curr(rq);
 }
 
 static int balance_rt(struct rq *rq, struct task_struct *p, struct rq_flags *rf)
 {
     if (!on_rt_rq(&p->rt) && need_pull_rt_task(rq, p)) {
         /*
          * 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've
          * not yet started the picking loop.
          */
         rq_unpin_lock(rq, rf);
         pull_rt_task(rq);
         rq_repin_lock(rq, rf);
     }
 
     return sched_stop_runnable(rq) || sched_dl_runnable(rq) || sched_rt_runnable(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 inline void set_next_task_rt(struct rq *rq, struct task_struct *p, bool first)
 {
     struct sched_rt_entity *rt_se = &p->rt;
     struct rt_rq *rt_rq = &rq->rt;
 
     p->se.exec_start = rq_clock_task(rq);
     if (on_rt_rq(&p->rt))
         update_stats_wait_end_rt(rt_rq, rt_se);
 
     /* The running task is never eligible for pushing */
     dequeue_pushable_task(rq, p);
 
     if (!first)
         return;
 
     /*
      * If prev task was rt, put_prev_task() has already updated the
      * utilization. We only care of the case where we start to schedule a
      * rt task
      */
     if (rq->curr->sched_class != &rt_sched_class)
         update_rt_rq_load_avg(rq_clock_pelt(rq), rq, 0);
 
     rt_queue_push_tasks(rq);
 }
 
 static struct sched_rt_entity *pick_next_rt_entity(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 rt_rq *rt_rq  = &rq->rt;
 
     do {
         rt_se = pick_next_rt_entity(rt_rq);
         BUG_ON(!rt_se);
         rt_rq = group_rt_rq(rt_se);
     } while (rt_rq);
 
     return rt_task_of(rt_se);
 }
 
 static struct task_struct *pick_task_rt(struct rq *rq)
 {
     struct task_struct *p;
 
     if (!sched_rt_runnable(rq))
         return NULL;
 
     p = _pick_next_task_rt(rq);
 
     return p;
 }
 
 static struct task_struct *pick_next_task_rt(struct rq *rq)
 {
     struct task_struct *p = pick_task_rt(rq);
 
     if (p)
         set_next_task_rt(rq, p, true);
 
     return p;
 }
 
 static void put_prev_task_rt(struct rq *rq, struct task_struct *p)
 {
     struct sched_rt_entity *rt_se = &p->rt;
     struct rt_rq *rt_rq = &rq->rt;
 
     if (on_rt_rq(&p->rt))
         update_stats_wait_start_rt(rt_rq, rt_se);
 
     update_curr_rt(rq);
 
     update_rt_rq_load_avg(rq_clock_pelt(rq), rq, 1);
 
     /*
      * The previous task needs to be made eligible for pushing
      * if it is still active
      */
     if (on_rt_rq(&p->rt) && p->nr_cpus_allowed > 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, &p->cpus_mask))
         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);
     int ret;
 
     /* Make sure the mask is initialized first */
     if (unlikely(!lowest_mask))
         return -1;
 
     if (task->nr_cpus_allowed == 1)
         return -1; /* No other targets possible */
 
     /*
      * If we're on asym system ensure we consider the different capacities
      * of the CPUs when searching for the lowest_mask.
      */
     if (static_branch_unlikely(&sched_asym_cpucapacity)) {
 
         ret = cpupri_find_fitness(&task_rq(task)->rd->cpupri,
                       task, lowest_mask,
                       rt_task_fits_capacity);
     } else {
 
         ret = cpupri_find(&task_rq(task)->rd->cpupri,
                   task, lowest_mask);
     }
 
     if (!ret)
         return -1; /* No targets found */
 
     /*
      * At this point we have built a mask of CPUs representing the
      * lowest priority tasks in the system.  Now we want to elect
      * the best one based on our affinity and topology.
      *
      * We prioritize the last CPU that the task executed on since
      * it is most likely cache-hot in that location.
      */
     if (cpumask_test_cpu(cpu, lowest_mask))
         return cpu;
 
     /*
      * Otherwise, we consult the sched_domains span maps to figure
      * out which CPU is logically closest to our hot cache data.
      */
     if (!cpumask_test_cpu(this_cpu, lowest_mask))
         this_cpu = -1; /* Skip this_cpu opt if not among lowest */
 
     rcu_read_lock();
     for_each_domain(cpu, sd) {
         if (sd->flags & SD_WAKE_AFFINE) {
             int best_cpu;
 
             /*
              * "this_cpu" is cheaper to preempt than a
              * remote processor.
              */
             if (this_cpu != -1 &&
                 cpumask_test_cpu(this_cpu, sched_domain_span(sd))) {
                 rcu_read_unlock();
                 return this_cpu;
             }
 
             best_cpu = cpumask_any_and_distribute(lowest_mask,
                                   sched_domain_span(sd));
             if (best_cpu < nr_cpu_ids) {
                 rcu_read_unlock();
                 return best_cpu;
             }
         }
     }
     rcu_read_unlock();
 
     /*
      * And finally, if there were no matches within the domains
      * just give the caller *something* to work with from the compatible
      * locations.
      */
     if (this_cpu != -1)
         return this_cpu;
 
     cpu = cpumask_any_distribute(lowest_mask);
     if (cpu < nr_cpu_ids)
         return cpu;
 
     return -1;
 }
 
 /* Will lock the rq it finds */
 static struct rq *find_lock_lowest_rq(struct task_struct *task, struct rq *rq)
 {
     struct rq *lowest_rq = NULL;
     int tries;
     int cpu;
 
     for (tries = 0; tries < RT_MAX_TRIES; tries++) {
         cpu = find_lowest_rq(task);
 
         if ((cpu == -1) || (cpu == rq->cpu))
             break;
 
         lowest_rq = cpu_rq(cpu);
 
         if (lowest_rq->rt.highest_prio.curr <= task->prio) {
             /*
              * Target rq has tasks of equal or higher priority,
              * retrying does not release any lock and is unlikely
              * to yield a different result.
              */
             lowest_rq = NULL;
             break;
         }
 
         /* if the prio of this runqueue changed, try again */
         if (double_lock_balance(rq, lowest_rq)) {
             /*
              * We had to unlock the run queue. In
              * the mean time, task could have
              * migrated already or had its affinity changed.
              * Also make sure that it wasn't scheduled on its rq.
              */
             if (unlikely(task_rq(task) != rq ||
                      !cpumask_test_cpu(lowest_rq->cpu, &task->cpus_mask) ||
                      task_running(rq, task) ||
                      !rt_task(task) ||
                      !task_on_rq_queued(task))) {
 
                 double_unlock_balance(rq, lowest_rq);
                 lowest_rq = NULL;
                 break;
             }
         }
 
         /* If this rq is still suitable use it. */
         if (lowest_rq->rt.highest_prio.curr > task->prio)
             break;
 
         /* try again */
         double_unlock_balance(rq, lowest_rq);
         lowest_rq = NULL;
     }
 
     return lowest_rq;
 }
 
 static struct task_struct *pick_next_pushable_task(struct rq *rq)
 {
     struct task_struct *p;
 
     if (!has_pushable_tasks(rq))
         return NULL;
 
     p = plist_first_entry(&rq->rt.pushable_tasks,
                   struct task_struct, pushable_tasks);
 
     BUG_ON(rq->cpu != task_cpu(p));
     BUG_ON(task_current(rq, p));
     BUG_ON(p->nr_cpus_allowed <= 1);
 
     BUG_ON(!task_on_rq_queued(p));
     BUG_ON(!rt_task(p));
 
     return p;
 }
 
 /*
  * If the current CPU has more than one RT task, see if the non
  * running task can migrate over to a CPU that is running a task
  * of lesser priority.
  */
 static int push_rt_task(struct rq *rq, bool pull)
 {
     struct task_struct *next_task;
     struct rq *lowest_rq;
     int ret = 0;
 
     if (!rq->rt.overloaded)
         return 0;
 
     next_task = pick_next_pushable_task(rq);
     if (!next_task)
         return 0;
 
 retry:
     /*
      * It's possible that the next_task slipped in of
      * higher priority than current. If that's the case
      * just reschedule current.
      */
     if (unlikely(next_task->prio < rq->curr->prio)) {
         resched_curr(rq);
         return 0;
     }
 
     if (is_migration_disabled(next_task)) {
         struct task_struct *push_task = NULL;
         int cpu;
 
         if (!pull || rq->push_busy)
             return 0;
 
         /*
          * Invoking find_lowest_rq() on anything but an RT task doesn't
          * make sense. Per the above priority check, curr has to
          * be of higher priority than next_task, so no need to
          * reschedule when bailing out.
          *
          * Note that the stoppers are masqueraded as SCHED_FIFO
          * (cf. sched_set_stop_task()), so we can't rely on rt_task().
          */
         if (rq->curr->sched_class != &rt_sched_class)
             return 0;
 
         cpu = find_lowest_rq(rq->curr);
         if (cpu == -1 || cpu == rq->cpu)
             return 0;
 
         /*
          * Given we found a CPU with lower priority than @next_task,
          * therefore it should be running. However we cannot migrate it
          * to this other CPU, instead attempt to push the current
          * running task on this CPU away.
          */
         push_task = get_push_task(rq);
         if (push_task) {
             raw_spin_rq_unlock(rq);
             stop_one_cpu_nowait(rq->cpu, push_cpu_stop,
                         push_task, &rq->push_work);
             raw_spin_rq_lock(rq);
         }
 
         return 0;
     }
 
     if (WARN_ON(next_task == rq->curr))
         return 0;
 
     /* We might release rq lock */
     get_task_struct(next_task);
 
     /* find_lock_lowest_rq locks the rq if found */
     lowest_rq = find_lock_lowest_rq(next_task, rq);
     if (!lowest_rq) {
         struct task_struct *task;
         /*
          * find_lock_lowest_rq releases rq->lock
          * so it is possible that next_task has migrated.
          *
          * We need to make sure that the task is still on the same
          * run-queue and is also still the next task eligible for
          * pushing.
          */
         task = pick_next_pushable_task(rq);
         if (task == next_task) {
             /*
              * The task hasn't migrated, and is still the next
              * eligible task, but we failed to find a run-queue
              * to push it to.  Do not retry in this case, since
              * other CPUs will pull from us when ready.
              */
             goto out;
         }
 
         if (!task)
             /* No more tasks, just exit */
             goto out;
 
         /*
          * Something has shifted, try again.
          */
         put_task_struct(next_task);
         next_task = task;
         goto retry;
     }
 
     deactivate_task(rq, next_task, 0);
     set_task_cpu(next_task, lowest_rq->cpu);
     activate_task(lowest_rq, next_task, 0);
     resched_curr(lowest_rq);
     ret = 1;
 
     double_unlock_balance(rq, lowest_rq);
 out:
     put_task_struct(next_task);
 
     return ret;
 }
 
 static void push_rt_tasks(struct rq *rq)
 {
     /* push_rt_task will return true if it moved an RT */
     while (push_rt_task(rq, false))
         ;
 }
 
 #ifdef HAVE_RT_PUSH_IPI
 
 /*
  * When a high priority task schedules out from a CPU and a lower priority
  * task is scheduled in, a check is made to see if there's any RT tasks
  * on other CPUs that are waiting to run because a higher priority RT task
  * is currently running on its CPU. In this case, the CPU with multiple RT
  * tasks queued on it (overloaded) needs to be notified that a CPU has opened
  * up that may be able to run one of its non-running queued RT tasks.
  *
  * All CPUs with overloaded RT tasks need to be notified as there is currently
  * no way to know which of these CPUs have the highest priority task waiting
  * to run. Instead of trying to take a spinlock on each of these CPUs,
  * which has shown to cause large latency when done on machines with many
  * CPUs, sending an IPI to the CPUs to have them push off the overloaded
  * RT tasks waiting to run.
  *
  * Just sending an IPI to each of the CPUs is also an issue, as on large
  * count CPU machines, this can cause an IPI storm on a CPU, especially
  * if its the only CPU with multiple RT tasks queued, and a large number
  * of CPUs scheduling a lower priority task at the same time.
  *
  * Each root domain has its own irq work function that can iterate over
  * all CPUs with RT overloaded tasks. Since all CPUs with overloaded RT
  * task must be checked if there's one or many CPUs that are lowering
  * their priority, there's a single irq work iterator that will try to
  * push off RT tasks that are waiting to run.
  *
  * When a CPU schedules a lower priority task, it will kick off the
  * irq work iterator that will jump to each CPU with overloaded RT tasks.
  * As it only takes the first CPU that schedules a lower priority task
  * to start the process, the rto_start variable is incremented and if
  * the atomic result is one, then that CPU will try to take the rto_lock.
  * This prevents high contention on the lock as the process handles all
  * CPUs scheduling lower priority tasks.
  *
  * All CPUs that are scheduling a lower priority task will increment the
  * rt_loop_next variable. This will make sure that the irq work iterator
  * checks all RT overloaded CPUs whenever a CPU schedules a new lower
  * priority task, even if the iterator is in the middle of a scan. Incrementing
  * the rt_loop_next will cause the iterator to perform another scan.
  *
  */
 static int rto_next_cpu(struct root_domain *rd)
 {
     int next;
     int cpu;
 
     /*
      * When starting the IPI RT pushing, the rto_cpu is set to -1,
      * rt_next_cpu() will simply return the first CPU found in
      * the rto_mask.
      *
      * If rto_next_cpu() is called with rto_cpu is a valid CPU, it
      * will return the next CPU found in the rto_mask.
      *
      * If there are no more CPUs left in the rto_mask, then a check is made
      * against rto_loop and rto_loop_next. rto_loop is only updated with
      * the rto_lock held, but any CPU may increment the rto_loop_next
      * without any locking.
      */
     for (;;) {
 
         /* When rto_cpu is -1 this acts like cpumask_first() */
         cpu = cpumask_next(rd->rto_cpu, rd->rto_mask);
 
         rd->rto_cpu = cpu;
 
         if (cpu < nr_cpu_ids)
             return cpu;
 
         rd->rto_cpu = -1;
 
         /*
          * ACQUIRE ensures we see the @rto_mask changes
          * made prior to the @next value observed.
          *
          * Matches WMB in rt_set_overload().
          */
         next = atomic_read_acquire(&rd->rto_loop_next);
 
         if (rd->rto_loop == next)
             break;
 
         rd->rto_loop = next;
     }
 
     return -1;
 }
 
 static inline bool rto_start_trylock(atomic_t *v)
 {
     return !atomic_cmpxchg_acquire(v, 0, 1);
 }
 
 static inline void rto_start_unlock(atomic_t *v)
 {
     atomic_set_release(v, 0);
 }
 
 static void tell_cpu_to_push(struct rq *rq)
 {
     int cpu = -1;
 
     /* Keep the loop going if the IPI is currently active */
     atomic_inc(&rq->rd->rto_loop_next);
 
     /* Only one CPU can initiate a loop at a time */
     if (!rto_start_trylock(&rq->rd->rto_loop_start))
         return;
 
     raw_spin_lock(&rq->rd->rto_lock);
 
     /*
      * The rto_cpu is updated under the lock, if it has a valid CPU
      * then the IPI is still running and will continue due to the
      * update to loop_next, and nothing needs to be done here.
      * Otherwise it is finishing up and an ipi needs to be sent.
      */
     if (rq->rd->rto_cpu < 0)
         cpu = rto_next_cpu(rq->rd);
 
     raw_spin_unlock(&rq->rd->rto_lock);
 
     rto_start_unlock(&rq->rd->rto_loop_start);
 
     if (cpu >= 0) {
         /* Make sure the rd does not get freed while pushing */
         sched_get_rd(rq->rd);
         irq_work_queue_on(&rq->rd->rto_push_work, cpu);
     }
 }
 
 /* Called from hardirq context */
 void rto_push_irq_work_func(struct irq_work *work)
 {
     struct root_domain *rd =
         container_of(work, struct root_domain, rto_push_work);
     struct rq *rq;
     int cpu;
 
     rq = this_rq();
 
     /*
      * We do not need to grab the lock to check for has_pushable_tasks.
      * When it gets updated, a check is made if a push is possible.
      */
     if (has_pushable_tasks(rq)) {
         raw_spin_rq_lock(rq);
         while (push_rt_task(rq, true))
             ;
         raw_spin_rq_unlock(rq);
     }
 
     raw_spin_lock(&rd->rto_lock);
 
     /* Pass the IPI to the next rt overloaded queue */
     cpu = rto_next_cpu(rd);
 
     raw_spin_unlock(&rd->rto_lock);
 
     if (cpu < 0) {
         sched_put_rd(rd);
         return;
     }
 
     /* Try the next RT overloaded CPU */
     irq_work_queue_on(&rd->rto_push_work, cpu);
 }
 #endif /* HAVE_RT_PUSH_IPI */
 
 static void pull_rt_task(struct rq *this_rq)
 {
     int this_cpu = this_rq->cpu, cpu;
     bool resched = false;
     struct task_struct *p, *push_task;
     struct rq *src_rq;
     int rt_overload_count = rt_overloaded(this_rq);
 
     if (likely(!rt_overload_count))
         return;
 
     /*
      * Match the barrier from rt_set_overloaded; this guarantees that if we
      * see overloaded we must also see the rto_mask bit.
      */
     smp_rmb();
 
     /* If we are the only overloaded CPU do nothing */
     if (rt_overload_count == 1 &&
         cpumask_test_cpu(this_rq->cpu, this_rq->rd->rto_mask))
         return;
 
 #ifdef HAVE_RT_PUSH_IPI
     if (sched_feat(RT_PUSH_IPI)) {
         tell_cpu_to_push(this_rq);
         return;
     }
 #endif
 
     for_each_cpu(cpu, this_rq->rd->rto_mask) {
         if (this_cpu == cpu)
             continue;
 
         src_rq = cpu_rq(cpu);
 
         /*
          * Don't bother taking the src_rq->lock if the next highest
          * task is known to be lower-priority than our current task.
          * This may look racy, but if this value is about to go
          * logically higher, the src_rq will push this task away.
          * And if its going logically lower, we do not care
          */
         if (src_rq->rt.highest_prio.next >=
             this_rq->rt.highest_prio.curr)
             continue;
 
         /*
          * We can potentially drop this_rq's lock in
          * double_lock_balance, and another CPU could
          * alter this_rq
          */
         push_task = NULL;
         double_lock_balance(this_rq, src_rq);
 
         /*
          * We can pull only a task, which is pushable
          * on its rq, and no others.
          */
         p = pick_highest_pushable_task(src_rq, this_cpu);
 
         /*
          * Do we have an RT task that preempts
          * the to-be-scheduled task?
          */
         if (p && (p->prio < this_rq->rt.highest_prio.curr)) {
             WARN_ON(p == src_rq->curr);
             WARN_ON(!task_on_rq_queued(p));
 
             /*
              * There's a chance that p is higher in priority
              * than what's currently running on its CPU.
              * This is just that p is waking up and hasn't
              * had a chance to schedule. We only pull
              * p if it is lower in priority than the
              * current task on the run queue
              */
             if (p->prio < src_rq->curr->prio)
                 goto skip;
 
             if (is_migration_disabled(p)) {
                 push_task = get_push_task(src_rq);
             } else {
                 deactivate_task(src_rq, p, 0);
                 set_task_cpu(p, this_cpu);
                 activate_task(this_rq, p, 0);
                 resched = true;
             }
             /*
              * We continue with the search, just in
              * case there's an even higher prio task
              * in another runqueue. (low likelihood
              * but possible)
              */
         }
 skip:
         double_unlock_balance(this_rq, src_rq);
 
         if (push_task) {
             raw_spin_rq_unlock(this_rq);
             stop_one_cpu_nowait(src_rq->cpu, push_cpu_stop,
                         push_task, &src_rq->push_work);
             raw_spin_rq_lock(this_rq);
         }
     }
 
     if (resched)
         resched_curr(this_rq);
 }
 
 /*
  * If we are not running and we are not going to reschedule soon, we should
  * try to push tasks away now
  */
 static void task_woken_rt(struct rq *rq, struct task_struct *p)
 {
     bool need_to_push = !task_running(rq, p) &&
                 !test_tsk_need_resched(rq->curr) &&
                 p->nr_cpus_allowed > 1 &&
                 (dl_task(rq->curr) || rt_task(rq->curr)) &&
                 (rq->curr->nr_cpus_allowed < 2 ||
                  rq->curr->prio <= p->prio);
 
     if (need_to_push)
         push_rt_tasks(rq);
 }
 
 /* Assumes rq->lock is held */
 static void rq_online_rt(struct rq *rq)
 {
     if (rq->rt.overloaded)
         rt_set_overload(rq);
 
     __enable_runtime(rq);
 
     cpupri_set(&rq->rd->cpupri, rq->cpu, rq->rt.highest_prio.curr);
 }
 
 /* Assumes rq->lock is held */
 static void rq_offline_rt(struct rq *rq)
 {
     if (rq->rt.overloaded)
         rt_clear_overload(rq);
 
     __disable_runtime(rq);
 
     cpupri_set(&rq->rd->cpupri, rq->cpu, CPUPRI_INVALID);
 }
 
 /*
  * When switch from the rt queue, we bring ourselves to a position
  * that we might want to pull RT tasks from other runqueues.
  */
 static void switched_from_rt(struct rq *rq, struct task_struct *p)
 {
     /*
      * If there are other RT tasks then we will reschedule
      * and the scheduling of the other RT tasks will handle
      * the balancing. But if we are the last RT task
      * we may need to handle the pulling of RT tasks
      * now.
      */
     if (!task_on_rq_queued(p) || rq->rt.rt_nr_running)
         return;
 
     rt_queue_pull_task(rq);
 }
 
 void __init init_sched_rt_class(void)
 {
     unsigned int i;
 
     for_each_possible_cpu(i) {
         zalloc_cpumask_var_node(&per_cpu(local_cpu_mask, i),
                     GFP_KERNEL, cpu_to_node(i));
     }
 }
 #endif /* CONFIG_SMP */
 
 /*
  * When switching a task to RT, we may overload the runqueue
  * with RT tasks. In this case we try to push them off to
  * other runqueues.
  */
 static void switched_to_rt(struct rq *rq, struct task_struct *p)
 {
     /*
      * If we are running, update the avg_rt tracking, as the running time
      * will now on be accounted into the latter.
      */
     if (task_current(rq, p)) {
         update_rt_rq_load_avg(rq_clock_pelt(rq), rq, 0);
         return;
     }
 
     /*
      * If we are not running we may need to preempt the current
      * running task. If that current running task is also an RT task
      * then see if we can move to another run queue.
      */
     if (task_on_rq_queued(p)) {
 #ifdef CONFIG_SMP
         if (p->nr_cpus_allowed > 1 && rq->rt.overloaded)
             rt_queue_push_tasks(rq);
 #endif /* CONFIG_SMP */
         if (p->prio < rq->curr->prio && cpu_online(cpu_of(rq)))
             resched_curr(rq);
     }
 }
 
 /*
  * Priority of the task has changed. This may cause
  * us to initiate a push or pull.
  */
 static void
 prio_changed_rt(struct rq *rq, struct task_struct *p, int oldprio)
 {
     if (!task_on_rq_queued(p))
         return;
 
     if (task_current(rq, p)) {
 #ifdef CONFIG_SMP
         /*
          * If our priority decreases while running, we
          * may need to pull tasks to this runqueue.
          */
         if (oldprio < p->prio)
             rt_queue_pull_task(rq);
 
         /*
          * If there's a higher priority task waiting to run
          * then reschedule.
          */
         if (p->prio > rq->rt.highest_prio.curr)
             resched_curr(rq);
 #else
         /* For UP simply resched on drop of prio */
         if (oldprio < p->prio)
             resched_curr(rq);
 #endif /* CONFIG_SMP */
     } else {
         /*
          * This task is not running, but if it is
          * greater than the current running task
          * then reschedule.
          */
         if (p->prio < rq->curr->prio)
             resched_curr(rq);
     }
 }
 
 #ifdef CONFIG_POSIX_TIMERS
 static void watchdog(struct rq *rq, struct task_struct *p)
 {
     unsigned long soft, hard;
 
     /* max may change after cur was read, this will be fixed next tick */
     soft = task_rlimit(p, RLIMIT_RTTIME);
     hard = task_rlimit_max(p, RLIMIT_RTTIME);
 
     if (soft != RLIM_INFINITY) {
         unsigned long next;
 
         if (p->rt.watchdog_stamp != jiffies) {
             p->rt.timeout++;
             p->rt.watchdog_stamp = jiffies;
         }
 
         next = DIV_ROUND_UP(min(soft, hard), USEC_PER_SEC/HZ);
         if (p->rt.timeout > next) {
             posix_cputimers_rt_watchdog(&p->posix_cputimers,
                             p->se.sum_exec_runtime);
         }
     }
 }
 #else
 static inline void watchdog(struct rq *rq, struct task_struct *p) { }
 #endif
 
 /*
  * scheduler tick hitting a task of our scheduling class.
  *
  * NOTE: This function can be called remotely by the tick offload that
  * goes along full dynticks. Therefore no local assumption can be made
  * and everything must be accessed through the @rq and @curr passed in
  * parameters.
  */
 static void task_tick_rt(struct rq *rq, struct task_struct *p, int queued)
 {
     struct sched_rt_entity *rt_se = &p->rt;
 
     update_curr_rt(rq);
     update_rt_rq_load_avg(rq_clock_pelt(rq), rq, 1);
 
     watchdog(rq, p);
 
     /*
      * RR tasks need a special form of timeslice management.
      * FIFO tasks have no timeslices.
      */
     if (p->policy != SCHED_RR)
         return;
 
     if (--p->rt.time_slice)
         return;
 
     p->rt.time_slice = sched_rr_timeslice;
 
     /*
      * Requeue to the end of queue if we (and all of our ancestors) are not
      * the only element on the queue
      */
     for_each_sched_rt_entity(rt_se) {
         if (rt_se->run_list.prev != rt_se->run_list.next) {
             requeue_task_rt(rq, p, 0);
             resched_curr(rq);
             return;
         }
     }
 }
 
 static unsigned int get_rr_interval_rt(struct rq *rq, struct task_struct *task)
 {
     /*
      * Time slice is 0 for SCHED_FIFO tasks
      */
     if (task->policy == SCHED_RR)
         return sched_rr_timeslice;
     else
         return 0;
 }
 
 DEFINE_SCHED_CLASS(rt) = {
 
     .enqueue_task       = enqueue_task_rt,
     .dequeue_task       = dequeue_task_rt,
     .yield_task     = yield_task_rt,
 
     .check_preempt_curr = check_preempt_curr_rt,
 
     .pick_next_task     = pick_next_task_rt,
     .put_prev_task      = put_prev_task_rt,
     .set_next_task          = set_next_task_rt,
 
 #ifdef CONFIG_SMP
     .balance        = balance_rt,
     .pick_task      = pick_task_rt,
     .select_task_rq     = select_task_rq_rt,
     .set_cpus_allowed       = set_cpus_allowed_common,
     .rq_online              = rq_online_rt,
     .rq_offline             = rq_offline_rt,
     .task_woken     = task_woken_rt,
     .switched_from      = switched_from_rt,
     .find_lock_rq       = find_lock_lowest_rq,
 #endif
 
     .task_tick      = task_tick_rt,
 
     .get_rr_interval    = get_rr_interval_rt,
 
     .prio_changed       = prio_changed_rt,
     .switched_to        = switched_to_rt,
 
     .update_curr        = update_curr_rt,
 
 #ifdef CONFIG_UCLAMP_TASK
     .uclamp_enabled     = 1,
 #endif
 };
 
 #ifdef CONFIG_RT_GROUP_SCHED
 /*
  * Ensure that the real time constraints are schedulable.
  */
 static DEFINE_MUTEX(rt_constraints_mutex);
 
 static inline int tg_has_rt_tasks(struct task_group *tg)
 {
     struct task_struct *task;
     struct css_task_iter it;
     int ret = 0;
 
     /*
      * Autogroups do not have RT tasks; see autogroup_create().
      */
     if (task_group_is_autogroup(tg))
         return 0;
 
     css_task_iter_start(&tg->css, 0, &it);
     while (!ret && (task = css_task_iter_next(&it)))
         ret |= rt_task(task);
     css_task_iter_end(&it);
 
     return ret;
 }
 
 struct rt_schedulable_data {
     struct task_group *tg;
     u64 rt_period;
     u64 rt_runtime;
 };
 
 static int tg_rt_schedulable(struct task_group *tg, void *data)
 {
     struct rt_schedulable_data *d = data;
     struct task_group *child;
     unsigned long total, sum = 0;
     u64 period, runtime;
 
     period = ktime_to_ns(tg->rt_bandwidth.rt_period);
     runtime = tg->rt_bandwidth.rt_runtime;
 
     if (tg == d->tg) {
         period = d->rt_period;
         runtime = d->rt_runtime;
     }
 
     /*
      * Cannot have more runtime than the period.
      */
     if (runtime > period && runtime != RUNTIME_INF)
         return -EINVAL;
 
     /*
      * Ensure we don't starve existing RT tasks if runtime turns zero.
      */
     if (rt_bandwidth_enabled() && !runtime &&
         tg->rt_bandwidth.rt_runtime && tg_has_rt_tasks(tg))
         return -EBUSY;
 
     total = to_ratio(period, runtime);
 
     /*
      * Nobody can have more than the global setting allows.
      */
     if (total > to_ratio(global_rt_period(), global_rt_runtime()))
         return -EINVAL;
 
     /*
      * The sum of our children's runtime should not exceed our own.
      */
     list_for_each_entry_rcu(child, &tg->children, siblings) {
         period = ktime_to_ns(child->rt_bandwidth.rt_period);
         runtime = child->rt_bandwidth.rt_runtime;
 
         if (child == d->tg) {
             period = d->rt_period;
             runtime = d->rt_runtime;
         }
 
         sum += to_ratio(period, runtime);
     }
 
     if (sum > total)
         return -EINVAL;
 
     return 0;
 }
 
 static int __rt_schedulable(struct task_group *tg, u64 period, u64 runtime)
 {
     int ret;
 
     struct rt_schedulable_data data = {
         .tg = tg,
         .rt_period = period,
         .rt_runtime = runtime,
     };
 
     rcu_read_lock();
     ret = walk_tg_tree(tg_rt_schedulable, tg_nop, &data);
     rcu_read_unlock();
 
     return ret;
 }
 
 static int tg_set_rt_bandwidth(struct task_group *tg,
         u64 rt_period, u64 rt_runtime)
 {
     int i, err = 0;
 
     /*
      * Disallowing the root group RT runtime is BAD, it would disallow the
      * kernel creating (and or operating) RT threads.
      */
     if (tg == &root_task_group && rt_runtime == 0)
         return -EINVAL;
 
     /* No period doesn't make any sense. */
     if (rt_period == 0)
         return -EINVAL;
 
     /*
      * Bound quota to defend quota against overflow during bandwidth shift.
      */
     if (rt_runtime != RUNTIME_INF && rt_runtime > max_rt_runtime)
         return -EINVAL;
 
     mutex_lock(&rt_constraints_mutex);
     err = __rt_schedulable(tg, rt_period, rt_runtime);
     if (err)
         goto unlock;
 
     raw_spin_lock_irq(&tg->rt_bandwidth.rt_runtime_lock);
     tg->rt_bandwidth.rt_period = ns_to_ktime(rt_period);
     tg->rt_bandwidth.rt_runtime = rt_runtime;
 
     for_each_possible_cpu(i) {
         struct rt_rq *rt_rq = tg->rt_rq[i];
 
         raw_spin_lock(&rt_rq->rt_runtime_lock);
         rt_rq->rt_runtime = rt_runtime;
         raw_spin_unlock(&rt_rq->rt_runtime_lock);
     }
     raw_spin_unlock_irq(&tg->rt_bandwidth.rt_runtime_lock);
 unlock:
     mutex_unlock(&rt_constraints_mutex);
 
     return err;
 }
 
 int sched_group_set_rt_runtime(struct task_group *tg, long rt_runtime_us)
 {
     u64 rt_runtime, rt_period;
 
     rt_period = ktime_to_ns(tg->rt_bandwidth.rt_period);
     rt_runtime = (u64)rt_runtime_us * NSEC_PER_USEC;
     if (rt_runtime_us < 0)
         rt_runtime = RUNTIME_INF;
     else if ((u64)rt_runtime_us > U64_MAX / NSEC_PER_USEC)
         return -EINVAL;
 
     return tg_set_rt_bandwidth(tg, rt_period, rt_runtime);
 }
 
 long sched_group_rt_runtime(struct task_group *tg)
 {
     u64 rt_runtime_us;
 
     if (tg->rt_bandwidth.rt_runtime == RUNTIME_INF)
         return -1;
 
     rt_runtime_us = tg->rt_bandwidth.rt_runtime;
     do_div(rt_runtime_us, NSEC_PER_USEC);
     return rt_runtime_us;
 }
 
 int sched_group_set_rt_period(struct task_group *tg, u64 rt_period_us)
 {
     u64 rt_runtime, rt_period;
 
     if (rt_period_us > U64_MAX / NSEC_PER_USEC)
         return -EINVAL;
 
     rt_period = rt_period_us * NSEC_PER_USEC;
     rt_runtime = tg->rt_bandwidth.rt_runtime;
 
     return tg_set_rt_bandwidth(tg, rt_period, rt_runtime);
 }
 
 long sched_group_rt_period(struct task_group *tg)
 {
     u64 rt_period_us;
 
     rt_period_us = ktime_to_ns(tg->rt_bandwidth.rt_period);
     do_div(rt_period_us, NSEC_PER_USEC);
     return rt_period_us;
 }
 
 #ifdef CONFIG_SYSCTL
 static int sched_rt_global_constraints(void)
 {
     int ret = 0;
 
     mutex_lock(&rt_constraints_mutex);
     ret = __rt_schedulable(NULL, 0, 0);
     mutex_unlock(&rt_constraints_mutex);
 
     return ret;
 }
 #endif /* CONFIG_SYSCTL */
 
 int sched_rt_can_attach(struct task_group *tg, struct task_struct *tsk)
 {
     /* Don't accept realtime tasks when there is no way for them to run */
     if (rt_task(tsk) && tg->rt_bandwidth.rt_runtime == 0)
         return 0;
 
     return 1;
 }
 
 #else /* !CONFIG_RT_GROUP_SCHED */
 
 #ifdef CONFIG_SYSCTL
 static int sched_rt_global_constraints(void)
 {
     unsigned long flags;
     int i;
 
     raw_spin_lock_irqsave(&def_rt_bandwidth.rt_runtime_lock, flags);
     for_each_possible_cpu(i) {
         struct rt_rq *rt_rq = &cpu_rq(i)->rt;
 
         raw_spin_lock(&rt_rq->rt_runtime_lock);
         rt_rq->rt_runtime = global_rt_runtime();
         raw_spin_unlock(&rt_rq->rt_runtime_lock);
     }
     raw_spin_unlock_irqrestore(&def_rt_bandwidth.rt_runtime_lock, flags);
 
     return 0;
 }
 #endif /* CONFIG_SYSCTL */
 #endif /* CONFIG_RT_GROUP_SCHED */
 
 #ifdef CONFIG_SYSCTL
 static int sched_rt_global_validate(void)
 {
     if (sysctl_sched_rt_period <= 0)
         return -EINVAL;
 
     if ((sysctl_sched_rt_runtime != RUNTIME_INF) &&
         ((sysctl_sched_rt_runtime > sysctl_sched_rt_period) ||
          ((u64)sysctl_sched_rt_runtime *
             NSEC_PER_USEC > max_rt_runtime)))
         return -EINVAL;
 
     return 0;
 }
 
 static void sched_rt_do_global(void)
 {
     unsigned long flags;
 
     raw_spin_lock_irqsave(&def_rt_bandwidth.rt_runtime_lock, flags);
     def_rt_bandwidth.rt_runtime = global_rt_runtime();
     def_rt_bandwidth.rt_period = ns_to_ktime(global_rt_period());
     raw_spin_unlock_irqrestore(&def_rt_bandwidth.rt_runtime_lock, flags);
 }
 
 static int sched_rt_handler(struct ctl_table *table, int write, void *buffer,
         size_t *lenp, loff_t *ppos)
 {
     int old_period, old_runtime;
     static DEFINE_MUTEX(mutex);
     int ret;
 
     mutex_lock(&mutex);
     old_period = sysctl_sched_rt_period;
     old_runtime = sysctl_sched_rt_runtime;
 
     ret = proc_dointvec(table, write, buffer, lenp, ppos);
 
     if (!ret && write) {
         ret = sched_rt_global_validate();
         if (ret)
             goto undo;
 
         ret = sched_dl_global_validate();
         if (ret)
             goto undo;
 
         ret = sched_rt_global_constraints();
         if (ret)
             goto undo;
 
         sched_rt_do_global();
         sched_dl_do_global();
     }
     if (0) {
 undo:
         sysctl_sched_rt_period = old_period;
         sysctl_sched_rt_runtime = old_runtime;
     }
     mutex_unlock(&mutex);
 
     return ret;
 }
 
 static int sched_rr_handler(struct ctl_table *table, int write, void *buffer,
         size_t *lenp, loff_t *ppos)
 {
     int ret;
     static DEFINE_MUTEX(mutex);
 
     mutex_lock(&mutex);
     ret = proc_dointvec(table, write, buffer, lenp, ppos);
     /*
      * Make sure that internally we keep jiffies.
      * Also, writing zero resets the timeslice to default:
      */
     if (!ret && write) {
         sched_rr_timeslice =
             sysctl_sched_rr_timeslice <= 0 ? RR_TIMESLICE :
             msecs_to_jiffies(sysctl_sched_rr_timeslice);
     }
     mutex_unlock(&mutex);
 
     return ret;
 }
 #endif /* CONFIG_SYSCTL */
 
 #ifdef CONFIG_SCHED_DEBUG
 void print_rt_stats(struct seq_file *m, int cpu)
 {
     rt_rq_iter_t iter;
     struct rt_rq *rt_rq;
 
     rcu_read_lock();
     for_each_rt_rq(rt_rq, iter, cpu_rq(cpu))
         print_rt_rq(m, cpu, rt_rq);
     rcu_read_unlock();
 }
 #endif /* CONFIG_SCHED_DEBUG */