1 files changed, 1866 insertions, 0 deletions

diff --git a/kernel/sched_rt.c b/kernel/sched_rt.c
new file mode 100644
index 00000000000..af1177858be
--- /dev/null
+++ b/kernel/sched_rt.c
@@ -0,0 +1,1866 @@
+/*
+ * Real-Time Scheduling Class (mapped to the SCHED_FIFO and SCHED_RR
+ * policies)
+ */
+
+#ifdef CONFIG_RT_GROUP_SCHED
+
+#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;
+}
+
+#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 rt_rq *rt_rq_of_se(struct sched_rt_entity *rt_se)
+{
+        struct task_struct *p = rt_task_of(rt_se);
+        struct rq *rq = task_rq(p);
+
+        return &rq->rt;
+}
+
+#endif /* CONFIG_RT_GROUP_SCHED */
+
+#ifdef CONFIG_SMP
+
+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.
+         */
+        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)
+{
+        if (!rt_entity_is_task(rt_se))
+                return;
+
+        rt_rq = &rq_of_rt_rq(rt_rq)->rt;
+
+        rt_rq->rt_nr_total++;
+        if (rt_se->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)
+{
+        if (!rt_entity_is_task(rt_se))
+                return;
+
+        rt_rq = &rq_of_rt_rq(rt_rq)->rt;
+
+        rt_rq->rt_nr_total--;
+        if (rt_se->nr_cpus_allowed > 1)
+                rt_rq->rt_nr_migratory--;
+
+        update_rt_migration(rt_rq);
+}
+
+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);
+}
+
+static void dequeue_pushable_task(struct rq *rq, struct task_struct *p)
+{
+        plist_del(&p->pushable_tasks, &rq->rt.pushable_tasks);
+}
+
+static inline int has_pushable_tasks(struct rq *rq)
+{
+        return !plist_head_empty(&rq->rt.pushable_tasks);
+}
+
+#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)
+{
+}
+
+#endif /* CONFIG_SMP */
+
+static inline int on_rt_rq(struct sched_rt_entity *rt_se)
+{
+        return !list_empty(&rt_se->run_list);
+}
+
+#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)]);)
+
+static inline void list_add_leaf_rt_rq(struct rt_rq *rt_rq)
+{
+        list_add_rcu(&rt_rq->leaf_rt_rq_list,
+                        &rq_of_rt_rq(rt_rq)->leaf_rt_rq_list);
+}
+
+static inline void list_del_leaf_rt_rq(struct rt_rq *rt_rq)
+{
+        list_del_rcu(&rt_rq->leaf_rt_rq_list);
+}
+
+#define for_each_leaf_rt_rq(rt_rq, rq) \
+        list_for_each_entry_rcu(rt_rq, &rq->leaf_rt_rq_list, leaf_rt_rq_list)
+
+#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, bool head);
+static void dequeue_rt_entity(struct sched_rt_entity *rt_se);
+
+static void sched_rt_rq_enqueue(struct rt_rq *rt_rq)
+{
+        struct task_struct *curr = rq_of_rt_rq(rt_rq)->curr;
+        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_rq->rt_nr_running) {
+                if (rt_se && !on_rt_rq(rt_se))
+                        enqueue_rt_entity(rt_se, false);
+                if (rt_rq->highest_prio.curr < curr->prio)
+                        resched_task(curr);
+        }
+}
+
+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 && on_rt_rq(rt_se))
+                dequeue_rt_entity(rt_se);
+}
+
+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 cpu_rq(smp_processor_id())->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)
+
+static inline void list_add_leaf_rt_rq(struct rt_rq *rt_rq)
+{
+}
+
+static inline void list_del_leaf_rt_rq(struct rt_rq *rt_rq)
+{
+}
+
+#define for_each_leaf_rt_rq(rt_rq, rq) \
+        for (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)
+{
+        if (rt_rq->rt_nr_running)
+                resched_task(rq_of_rt_rq(rt_rq)->curr);
+}
+
+static inline void sched_rt_rq_dequeue(struct 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 */
+
+#ifdef CONFIG_SMP
+/*
+ * We ran out of runtime, see if we can borrow some from our neighbours.
+ */
+static int do_balance_runtime(struct rt_rq *rt_rq)
+{
+        struct rt_bandwidth *rt_b = sched_rt_bandwidth(rt_rq);
+        struct root_domain *rd = cpu_rq(smp_processor_id())->rd;
+        int i, weight, more = 0;
+        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;
+                        more = 1;
+                        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);
+
+        return more;
+}
+
+/*
+ * 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;
+                raw_spin_unlock(&rt_rq->rt_runtime_lock);
+                raw_spin_unlock(&rt_b->rt_runtime_lock);
+        }
+}
+
+static void disable_runtime(struct rq *rq)
+{
+        unsigned long flags;
+
+        raw_spin_lock_irqsave(&rq->lock, flags);
+        __disable_runtime(rq);
+        raw_spin_unlock_irqrestore(&rq->lock, flags);
+}
+
+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 enable_runtime(struct rq *rq)
+{
+        unsigned long flags;
+
+        raw_spin_lock_irqsave(&rq->lock, flags);
+        __enable_runtime(rq);
+        raw_spin_unlock_irqrestore(&rq->lock, flags);
+}
+
+static int balance_runtime(struct rt_rq *rt_rq)
+{
+        int more = 0;
+
+        if (rt_rq->rt_time > rt_rq->rt_runtime) {
+                raw_spin_unlock(&rt_rq->rt_runtime_lock);
+                more = do_balance_runtime(rt_rq);
+                raw_spin_lock(&rt_rq->rt_runtime_lock);
+        }
+
+        return more;
+}
+#else /* !CONFIG_SMP */
+static inline int balance_runtime(struct rt_rq *rt_rq)
+{
+        return 0;
+}
+#endif /* CONFIG_SMP */
+
+static int do_sched_rt_period_timer(struct rt_bandwidth *rt_b, int overrun)
+{
+        int i, idle = 1;
+        const struct cpumask *span;
+
+        if (!rt_bandwidth_enabled() || rt_b->rt_runtime == RUNTIME_INF)
+                return 1;
+
+        span = sched_rt_period_mask();
+        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;
+
+                                /*
+                                 * Force a clock update if the CPU was idle,
+                                 * lest wakeup -> unthrottle time accumulate.
+                                 */
+                                if (rt_rq->rt_nr_running && rq->curr == rq->idle)
+                                        rq->skip_clock_update = -1;
+                        }
+                        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 (enqueue)
+                        sched_rt_rq_enqueue(rt_rq);
+                raw_spin_unlock(&rq->lock);
+        }
+
+        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 (sched_rt_runtime(rt_rq) >= 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) {
+                rt_rq->rt_throttled = 1;
+                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;
+        struct rt_rq *rt_rq = rt_rq_of_se(rt_se);
+        u64 delta_exec;
+
+        if (curr->sched_class != &rt_sched_class)
+                return;
+
+        delta_exec = rq->clock_task - curr->se.exec_start;
+        if (unlikely((s64)delta_exec < 0))
+                delta_exec = 0;
+
+        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;
+        cpuacct_charge(curr, delta_exec);
+
+        sched_rt_avg_update(rq, delta_exec);
+
+        if (!rt_bandwidth_enabled())
+                return;
+
+        for_each_sched_rt_entity(rt_se) {
+                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_task(curr);
+                        raw_spin_unlock(&rt_rq->rt_runtime_lock);
+                }
+        }
+}
+
+#if defined CONFIG_SMP
+
+static struct task_struct *pick_next_highest_task_rt(struct rq *rq, int cpu);
+
+static inline int next_prio(struct rq *rq)
+{
+        struct task_struct *next = pick_next_highest_task_rt(rq, rq->cpu);
+
+        if (next && rt_prio(next->prio))
+                return next->prio;
+        else
+                return MAX_RT_PRIO;
+}
+
+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);
+
+        if (prio < prev_prio) {
+
+                /*
+                 * If the new task is higher in priority than anything on the
+                 * run-queue, we know that the previous high becomes our
+                 * next-highest.
+                 */
+                rt_rq->highest_prio.next = prev_prio;
+
+                if (rq->online)
+                        cpupri_set(&rq->rd->cpupri, rq->cpu, prio);
+
+        } else if (prio == rt_rq->highest_prio.curr)
+                /*
+                 * If the next task is equal in priority to the highest on
+                 * the run-queue, then we implicitly know that the next highest
+                 * task cannot be any lower than current
+                 */
+                rt_rq->highest_prio.next = prio;
+        else if (prio < rt_rq->highest_prio.next)
+                /*
+                 * Otherwise, we need to recompute next-highest
+                 */
+                rt_rq->highest_prio.next = next_prio(rq);
+}
+
+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);
+
+        if (rt_rq->rt_nr_running && (prio <= rt_rq->highest_prio.next))
+                rt_rq->highest_prio.next = next_prio(rq);
+
+        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
+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++;
+
+        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--;
+
+        dec_rt_prio(rt_rq, rt_se_prio(rt_se));
+        dec_rt_migration(rt_se, rt_rq);
+        dec_rt_group(rt_se, rt_rq);
+}
+
+static void __enqueue_rt_entity(struct sched_rt_entity *rt_se, bool head)
+{
+        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))
+                return;
+
+        if (!rt_rq->rt_nr_running)
+                list_add_leaf_rt_rq(rt_rq);
+
+        if (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);
+
+        inc_rt_tasks(rt_se, rt_rq);
+}
+
+static void __dequeue_rt_entity(struct sched_rt_entity *rt_se)
+{
+        struct rt_rq *rt_rq = rt_rq_of_se(rt_se);
+        struct rt_prio_array *array = &rt_rq->active;
+
+        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);
+
+        dec_rt_tasks(rt_se, rt_rq);
+        if (!rt_rq->rt_nr_running)
+                list_del_leaf_rt_rq(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)
+{
+        struct sched_rt_entity *back = NULL;
+
+        for_each_sched_rt_entity(rt_se) {
+                rt_se->back = back;
+                back = rt_se;
+        }
+
+        for (rt_se = back; rt_se; rt_se = rt_se->back) {
+                if (on_rt_rq(rt_se))
+                        __dequeue_rt_entity(rt_se);
+        }
+}
+
+static void enqueue_rt_entity(struct sched_rt_entity *rt_se, bool head)
+{
+        dequeue_rt_stack(rt_se);
+        for_each_sched_rt_entity(rt_se)
+                __enqueue_rt_entity(rt_se, head);
+}
+
+static void dequeue_rt_entity(struct sched_rt_entity *rt_se)
+{
+        dequeue_rt_stack(rt_se);
+
+        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, false);
+        }
+}
+
+/*
+ * 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 & ENQUEUE_HEAD);
+
+        if (!task_current(rq, p) && p->rt.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);
+
+        dequeue_pushable_task(rq, p);
+}
+
+/*
+ * Put task to 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 sd_flag, int flags)
+{
+        struct task_struct *curr;
+        struct rq *rq;
+        int cpu;
+
+        if (sd_flag != SD_BALANCE_WAKE)
+                return smp_processor_id();
+
+        cpu = task_cpu(p);
+        rq = cpu_rq(cpu);
+
+        rcu_read_lock();
+        curr = ACCESS_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)) &&
+            (curr->rt.nr_cpus_allowed < 2 ||
+             curr->prio <= p->prio) &&
+            (p->rt.nr_cpus_allowed > 1)) {
+                int target = find_lowest_rq(p);
+
+                if (target != -1)
+                        cpu = target;
+        }
+        rcu_read_unlock();
+
+        return cpu;
+}
+
+static void check_preempt_equal_prio(struct rq *rq, struct task_struct *p)
+{
+        if (rq->curr->rt.nr_cpus_allowed == 1)
+                return;
+
+        if (p->rt.nr_cpus_allowed != 1
+            && cpupri_find(&rq->rd->cpupri, p, NULL))
+                return;
+
+        if (!cpupri_find(&rq->rd->cpupri, rq->curr, 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_task(rq->curr);
+}
+
+#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_task(rq->curr);
+                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;
+
+        rt_rq = &rq->rt;
+
+        if (!rt_rq->rt_nr_running)
+                return NULL;
+
+        if (rt_rq_throttled(rt_rq))
+                return NULL;
+
+        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;
+
+        return p;
+}
+
+static struct task_struct *pick_next_task_rt(struct rq *rq)
+{
+        struct task_struct *p = _pick_next_task_rt(rq);
+
+        /* The running task is never eligible for pushing */
+        if (p)
+                dequeue_pushable_task(rq, p);
+
+#ifdef CONFIG_SMP
+        /*
+         * We detect this state here so that we can avoid taking the RQ
+         * lock again later if there is no need to push
+         */
+        rq->post_schedule = has_pushable_tasks(rq);
+#endif
+
+        return p;
+}
+
+static void put_prev_task_rt(struct rq *rq, struct task_struct *p)
+{
+        update_curr_rt(rq);
+        p->se.exec_start = 0;
+
+        /*
+         * The previous task needs to be made eligible for pushing
+         * if it is still active
+         */
+        if (on_rt_rq(&p->rt) && p->rt.nr_cpus_allowed > 1)
+                enqueue_pushable_task(rq, p);
+}
+
+#ifdef CONFIG_SMP
+
+/* Only try algorithms three times */
+#define RT_MAX_TRIES 3
+
+static void deactivate_task(struct rq *rq, struct task_struct *p, int sleep);
+
+static int pick_rt_task(struct rq *rq, struct task_struct *p, int cpu)
+{
+        if (!task_running(rq, p) &&
+            (cpu < 0 || cpumask_test_cpu(cpu, &p->cpus_allowed)) &&
+            (p->rt.nr_cpus_allowed > 1))
+                return 1;
+        return 0;
+}
+
+/* Return the second highest RT task, NULL otherwise */
+static struct task_struct *pick_next_highest_task_rt(struct rq *rq, int cpu)
+{
+        struct task_struct *next = NULL;
+        struct sched_rt_entity *rt_se;
+        struct rt_prio_array *array;
+        struct rt_rq *rt_rq;
+        int idx;
+
+        for_each_leaf_rt_rq(rt_rq, rq) {
+                array = &rt_rq->active;
+                idx = sched_find_first_bit(array->bitmap);
+next_idx:
+                if (idx >= MAX_RT_PRIO)
+                        continue;
+                if (next && next->prio < idx)
+                        continue;
+                list_for_each_entry(rt_se, array->queue + idx, run_list) {
+                        struct task_struct *p;
+
+                        if (!rt_entity_is_task(rt_se))
+                                continue;
+
+                        p = rt_task_of(rt_se);
+                        if (pick_rt_task(rq, p, cpu)) {
+                                next = p;
+                                break;
+                        }
+                }
+                if (!next) {
+                        idx = find_next_bit(array->bitmap, MAX_RT_PRIO, idx+1);
+                        goto next_idx;
+                }
+        }
+
+        return next;
+}
+
+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 = __get_cpu_var(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 (task->rt.nr_cpus_allowed == 1)
+                return -1; /* No other targets possible */
+
+        if (!cpupri_find(&task_rq(task)->rd->cpupri, task, lowest_mask))
+                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_first_and(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(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 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_allowed) ||
+                                     task_running(rq, task) ||
+                                     !task->on_rq)) {
+
+                                raw_spin_unlock(&lowest_rq->lock);
+                                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->rt.nr_cpus_allowed <= 1);
+
+        BUG_ON(!p->on_rq);
+        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)
+{
+        struct task_struct *next_task;
+        struct rq *lowest_rq;
+
+        if (!rq->rt.overloaded)
+                return 0;
+
+        next_task = pick_next_pushable_task(rq);
+        if (!next_task)
+                return 0;
+
+retry:
+        if (unlikely(next_task == rq->curr)) {
+                WARN_ON(1);
+                return 0;
+        }
+
+        /*
+         * 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_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_cpu(next_task) == rq->cpu && task == next_task) {
+                        /*
+                         * If we get here, the task hasn't moved at all, but
+                         * it has failed to push.  We will not try again,
+                         * since the other cpus will pull from us when they
+                         * are ready.
+                         */
+                        dequeue_pushable_task(rq, next_task);
+                        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_task(lowest_rq->curr);
+
+        double_unlock_balance(rq, lowest_rq);
+
+out:
+        put_task_struct(next_task);
+
+        return 1;
+}
+
+static void push_rt_tasks(struct rq *rq)
+{
+        /* push_rt_task will return true if it moved an RT */
+        while (push_rt_task(rq))
+                ;
+}
+
+static int pull_rt_task(struct rq *this_rq)
+{
+        int this_cpu = this_rq->cpu, ret = 0, cpu;
+        struct task_struct *p;
+        struct rq *src_rq;
+
+        if (likely(!rt_overloaded(this_rq)))
+                return 0;
+
+        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
+                 */
+                double_lock_balance(this_rq, src_rq);
+
+                /*
+                 * Are there still pullable RT tasks?
+                 */
+                if (src_rq->rt.rt_nr_running <= 1)
+                        goto skip;
+
+                p = pick_next_highest_task_rt(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(!p->on_rq);
+
+                        /*
+                         * There's a chance that p is higher in priority
+                         * than what's currently running on its cpu.
+                         * This is just that p is wakeing 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;
+
+                        ret = 1;
+
+                        deactivate_task(src_rq, p, 0);
+                        set_task_cpu(p, this_cpu);
+                        activate_task(this_rq, p, 0);
+                        /*
+                         * 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);
+        }
+
+        return ret;
+}
+
+static void pre_schedule_rt(struct rq *rq, struct task_struct *prev)
+{
+        /* Try to pull RT tasks here if we lower this rq's prio */
+        if (rq->rt.highest_prio.curr > prev->prio)
+                pull_rt_task(rq);
+}
+
+static void post_schedule_rt(struct rq *rq)
+{
+        push_rt_tasks(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)
+{
+        if (!task_running(rq, p) &&
+            !test_tsk_need_resched(rq->curr) &&
+            has_pushable_tasks(rq) &&
+            p->rt.nr_cpus_allowed > 1 &&
+            rt_task(rq->curr) &&
+            (rq->curr->rt.nr_cpus_allowed < 2 ||
+             rq->curr->prio <= p->prio))
+                push_rt_tasks(rq);
+}
+
+static void set_cpus_allowed_rt(struct task_struct *p,
+                                const struct cpumask *new_mask)
+{
+        int weight = cpumask_weight(new_mask);
+
+        BUG_ON(!rt_task(p));
+
+        /*
+         * Update the migration status of the RQ if we have an RT task
+         * which is running AND changing its weight value.
+         */
+        if (p->on_rq && (weight != p->rt.nr_cpus_allowed)) {
+                struct rq *rq = task_rq(p);
+
+                if (!task_current(rq, p)) {
+                        /*
+                         * Make sure we dequeue this task from the pushable list
+                         * before going further.  It will either remain off of
+                         * the list because we are no longer pushable, or it
+                         * will be requeued.
+                         */
+                        if (p->rt.nr_cpus_allowed > 1)
+                                dequeue_pushable_task(rq, p);
+
+                        /*
+                         * Requeue if our weight is changing and still > 1
+                         */
+                        if (weight > 1)
+                                enqueue_pushable_task(rq, p);
+
+                }
+
+                if ((p->rt.nr_cpus_allowed <= 1) && (weight > 1)) {
+                        rq->rt.rt_nr_migratory++;
+                } else if ((p->rt.nr_cpus_allowed > 1) && (weight <= 1)) {
+                        BUG_ON(!rq->rt.rt_nr_migratory);
+                        rq->rt.rt_nr_migratory--;
+                }
+
+                update_rt_migration(&rq->rt);
+        }
+
+        cpumask_copy(&p->cpus_allowed, new_mask);
+        p->rt.nr_cpus_allowed = weight;
+}
+
+/* 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 (p->on_rq && !rq->rt.rt_nr_running)
+                pull_rt_task(rq);
+}
+
+static inline void 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)
+{
+        int check_resched = 1;
+
+        /*
+         * If we are already running, then there's nothing
+         * that needs to be done. But 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 (p->on_rq && rq->curr != p) {
+#ifdef CONFIG_SMP
+                if (rq->rt.overloaded && push_rt_task(rq) &&
+                    /* Don't resched if we changed runqueues */
+                    rq != task_rq(p))
+                        check_resched = 0;
+#endif /* CONFIG_SMP */
+                if (check_resched && p->prio < rq->curr->prio)
+                        resched_task(rq->curr);
+        }
+}
+
+/*
+ * 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 (!p->on_rq)
+                return;
+
+        if (rq->curr == p) {
+#ifdef CONFIG_SMP
+                /*
+                 * If our priority decreases while running, we
+                 * may need to pull tasks to this runqueue.
+                 */
+                if (oldprio < p->prio)
+                        pull_rt_task(rq);
+                /*
+                 * If there's a higher priority task waiting to run
+                 * then reschedule. Note, the above pull_rt_task
+                 * can release the rq lock and p could migrate.
+                 * Only reschedule if p is still on the same runqueue.
+                 */
+                if (p->prio > rq->rt.highest_prio.curr && rq->curr == p)
+                        resched_task(p);
+#else
+                /* For UP simply resched on drop of prio */
+                if (oldprio < p->prio)
+                        resched_task(p);
+#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_task(rq->curr);
+        }
+}
+
+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;
+
+                p->rt.timeout++;
+                next = DIV_ROUND_UP(min(soft, hard), USEC_PER_SEC/HZ);
+                if (p->rt.timeout > next)
+                        p->cputime_expires.sched_exp = p->se.sum_exec_runtime;
+        }
+}
+
+static void task_tick_rt(struct rq *rq, struct task_struct *p, int queued)
+{
+        update_curr_rt(rq);
+
+        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 = DEF_TIMESLICE;
+
+        /*
+         * Requeue to the end of queue if we are not the only element
+         * on the queue:
+         */
+        if (p->rt.run_list.prev != p->rt.run_list.next) {
+                requeue_task_rt(rq, p, 0);
+                set_tsk_need_resched(p);
+        }
+}
+
+static void set_curr_task_rt(struct rq *rq)
+{
+        struct task_struct *p = rq->curr;
+
+        p->se.exec_start = rq->clock_task;
+
+        /* The running task is never eligible for pushing */
+        dequeue_pushable_task(rq, p);
+}
+
+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 DEF_TIMESLICE;
+        else
+                return 0;
+}
+
+static const struct sched_class rt_sched_class = {
+        .next                   = &fair_sched_class,
+        .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,
+
+#ifdef CONFIG_SMP
+        .select_task_rq         = select_task_rq_rt,
+
+        .set_cpus_allowed       = set_cpus_allowed_rt,
+        .rq_online              = rq_online_rt,
+        .rq_offline             = rq_offline_rt,
+        .pre_schedule           = pre_schedule_rt,
+        .post_schedule          = post_schedule_rt,
+        .task_woken             = task_woken_rt,
+        .switched_from          = switched_from_rt,
+#endif
+
+        .set_curr_task          = set_curr_task_rt,
+        .task_tick              = task_tick_rt,
+
+        .get_rr_interval        = get_rr_interval_rt,
+
+        .prio_changed           = prio_changed_rt,
+        .switched_to            = switched_to_rt,
+};
+
+#ifdef CONFIG_SCHED_DEBUG
+extern void print_rt_rq(struct seq_file *m, int cpu, struct rt_rq *rt_rq);
+
+static 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 */
+