1 files changed, 65 insertions, 37 deletions

diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c
index 1999021042c7..d8cdf1618551 100644
--- a/kernel/sched/rt.c
+++ b/kernel/sched/rt.c
@@ -229,6 +229,14 @@ int alloc_rt_sched_group(struct task_group *tg, struct task_group *parent)
 
 #ifdef CONFIG_SMP
 
+static int pull_rt_task(struct rq *this_rq);
+
+static inline bool need_pull_rt_task(struct rq *rq, struct task_struct *prev)
+{
+        /* Try to pull RT tasks here if we lower this rq's prio */
+        return rq->rt.highest_prio.curr > prev->prio;
+}
+
 static inline int rt_overloaded(struct rq *rq)
 {
         return atomic_read(&rq->rd->rto_count);
@@ -315,6 +323,15 @@ static inline int has_pushable_tasks(struct rq *rq)
         return !plist_head_empty(&rq->rt.pushable_tasks);
 }
 
+static inline void set_post_schedule(struct rq *rq)
+{
+        /*
+         * 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);
+}
+
 static void enqueue_pushable_task(struct rq *rq, struct task_struct *p)
 {
         plist_del(&p->pushable_tasks, &rq->rt.pushable_tasks);
@@ -359,6 +376,19 @@ void dec_rt_migration(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
 {
 }
 
+static inline bool need_pull_rt_task(struct rq *rq, struct task_struct *prev)
+{
+        return false;
+}
+
+static inline int pull_rt_task(struct rq *this_rq)
+{
+        return 0;
+}
+
+static inline void set_post_schedule(struct rq *rq)
+{
+}
 #endif /* CONFIG_SMP */
 
 static inline int on_rt_rq(struct sched_rt_entity *rt_se)
@@ -440,11 +470,6 @@ static void sched_rt_rq_dequeue(struct rt_rq *rt_rq)
                 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);
@@ -515,11 +540,6 @@ 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;
@@ -1318,15 +1338,7 @@ 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;
+        struct rt_rq *rt_rq  = &rq->rt;
 
         do {
                 rt_se = pick_next_rt_entity(rq, rt_rq);
@@ -1340,21 +1352,45 @@ static struct task_struct *_pick_next_task_rt(struct rq *rq)
         return p;
 }
 
-static struct task_struct *pick_next_task_rt(struct rq *rq)
+static struct task_struct *
+pick_next_task_rt(struct rq *rq, struct task_struct *prev)
 {
-        struct task_struct *p = _pick_next_task_rt(rq);
+        struct task_struct *p;
+        struct rt_rq *rt_rq = &rq->rt;
+
+        if (need_pull_rt_task(rq, prev)) {
+                pull_rt_task(rq);
+                /*
+                 * pull_rt_task() can drop (and re-acquire) rq->lock; this
+                 * means a dl task can slip in, in which case we need to
+                 * re-start task selection.
+                 */
+                if (unlikely(rq->dl.dl_nr_running))
+                        return RETRY_TASK;
+        }
+
+        /*
+         * We may dequeue prev's rt_rq in put_prev_task().
+         * So, we update time before rt_nr_running check.
+         */
+        if (prev->sched_class == &rt_sched_class)
+                update_curr_rt(rq);
+
+        if (!rt_rq->rt_nr_running)
+                return NULL;
+
+        if (rt_rq_throttled(rt_rq))
+                return NULL;
+
+        put_prev_task(rq, prev);
+
+        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
+        set_post_schedule(rq);
 
         return p;
 }
@@ -1724,13 +1760,6 @@ skip:
         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);
@@ -1833,7 +1862,7 @@ static void switched_from_rt(struct rq *rq, struct task_struct *p)
                 resched_task(rq->curr);
 }
 
-void init_sched_rt_class(void)
+void __init init_sched_rt_class(void)
 {
         unsigned int i;
 
@@ -2007,7 +2036,6 @@ const struct sched_class rt_sched_class = {
         .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,