Merge tag 'tpm-fixes-for-4.2-rc2' of https://github.com/PeterHuewe/linux-tpmdd into...

[karo-tx-linux.git] / kernel / sched / rt.c

diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c
index 7d7093c51f8d169cea027c78a9ca0321c8f15932..0d193a243e96dce029c952a47858b2f0edfb8491 100644 (file)
--- a/kernel/sched/rt.c
+++ b/kernel/sched/rt.c
@@ -260,7 +260,7 @@ 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 void pull_rt_task(struct rq *this_rq);
 
 static inline bool need_pull_rt_task(struct rq *rq, struct task_struct *prev)
 {
@@ -354,13 +354,23 @@ 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)
+static DEFINE_PER_CPU(struct callback_head, rt_push_head);
+static DEFINE_PER_CPU(struct callback_head, rt_pull_head);
+
+static void push_rt_tasks(struct rq *);
+static void pull_rt_task(struct rq *);
+
+static inline void queue_push_tasks(struct rq *rq)
 {
-       /*
-        * 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);
+       if (!has_pushable_tasks(rq))
+               return;
+
+       queue_balance_callback(rq, &per_cpu(rt_push_head, rq->cpu), push_rt_tasks);
+}
+
+static inline void queue_pull_task(struct rq *rq)
+{
+       queue_balance_callback(rq, &per_cpu(rt_pull_head, rq->cpu), pull_rt_task);
 }
 
 static void enqueue_pushable_task(struct rq *rq, struct task_struct *p)
@@ -412,12 +422,11 @@ 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)
+static inline void pull_rt_task(struct rq *this_rq)
 {
-       return 0;
 }
 
-static inline void set_post_schedule(struct rq *rq)
+static inline void queue_push_tasks(struct rq *rq)
 {
 }
 #endif /* CONFIG_SMP */
@@ -1469,7 +1478,15 @@ pick_next_task_rt(struct rq *rq, struct task_struct *prev)
        struct rt_rq *rt_rq = &rq->rt;
 
        if (need_pull_rt_task(rq, prev)) {
+               /*
+                * This is OK, because current is on_cpu, which avoids it being
+                * picked for load-balance and preemption/IRQs are still
+                * disabled avoiding further scheduler activity on it and we're
+                * being very careful to re-start the picking loop.
+                */
+               lockdep_unpin_lock(&rq->lock);
                pull_rt_task(rq);
+               lockdep_pin_lock(&rq->lock);
                /*
                 * pull_rt_task() can drop (and re-acquire) rq->lock; this
                 * means a dl or stop task can slip in, in which case we need
@@ -1497,7 +1514,7 @@ pick_next_task_rt(struct rq *rq, struct task_struct *prev)
        /* The running task is never eligible for pushing */
        dequeue_pushable_task(rq, p);
 
-       set_post_schedule(rq);
+       queue_push_tasks(rq);
 
        return p;
 }
@@ -1952,14 +1969,15 @@ static void push_irq_work_func(struct irq_work *work)
 }
 #endif /* HAVE_RT_PUSH_IPI */
 
-static int pull_rt_task(struct rq *this_rq)
+static void pull_rt_task(struct rq *this_rq)
 {
-       int this_cpu = this_rq->cpu, ret = 0, cpu;
+       int this_cpu = this_rq->cpu, cpu;
+       bool resched = false;
        struct task_struct *p;
        struct rq *src_rq;
 
        if (likely(!rt_overloaded(this_rq)))
-               return 0;
+               return;
 
        /*
         * Match the barrier from rt_set_overloaded; this guarantees that if we
@@ -1970,7 +1988,7 @@ static int pull_rt_task(struct rq *this_rq)
 #ifdef HAVE_RT_PUSH_IPI
        if (sched_feat(RT_PUSH_IPI)) {
                tell_cpu_to_push(this_rq);
-               return 0;
+               return;
        }
 #endif
 
@@ -2023,7 +2041,7 @@ static int pull_rt_task(struct rq *this_rq)
                        if (p->prio < src_rq->curr->prio)
                                goto skip;
 
-                       ret = 1;
+                       resched = true;
 
                        deactivate_task(src_rq, p, 0);
                        set_task_cpu(p, this_cpu);
@@ -2039,12 +2057,8 @@ skip:
                double_unlock_balance(this_rq, src_rq);
        }
 
-       return ret;
-}
-
-static void post_schedule_rt(struct rq *rq)
-{
-       push_rt_tasks(rq);
+       if (resched)
+               resched_curr(this_rq);
 }
 
 /*
@@ -2140,8 +2154,7 @@ static void switched_from_rt(struct rq *rq, struct task_struct *p)
        if (!task_on_rq_queued(p) || rq->rt.rt_nr_running)
                return;
 
-       if (pull_rt_task(rq))
-               resched_curr(rq);
+       queue_pull_task(rq);
 }
 
 void __init init_sched_rt_class(void)
@@ -2162,8 +2175,6 @@ void __init init_sched_rt_class(void)
  */
 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
@@ -2173,13 +2184,12 @@ static void switched_to_rt(struct rq *rq, struct task_struct *p)
         */
        if (task_on_rq_queued(p) && rq->curr != p) {
 #ifdef CONFIG_SMP
-               if (p->nr_cpus_allowed > 1 && rq->rt.overloaded &&
-                   /* Don't resched if we changed runqueues */
-                   push_rt_task(rq) && rq != task_rq(p))
-                       check_resched = 0;
-#endif /* CONFIG_SMP */
-               if (check_resched && p->prio < rq->curr->prio)
+               if (p->nr_cpus_allowed > 1 && rq->rt.overloaded)
+                       queue_push_tasks(rq);
+#else
+               if (p->prio < rq->curr->prio)
                        resched_curr(rq);
+#endif /* CONFIG_SMP */
        }
 }
 
@@ -2200,14 +2210,13 @@ prio_changed_rt(struct rq *rq, struct task_struct *p, int oldprio)
                 * may need to pull tasks to this runqueue.
                 */
                if (oldprio < p->prio)
-                       pull_rt_task(rq);
+                       queue_pull_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.
+                * then reschedule.
                 */
-               if (p->prio > rq->rt.highest_prio.curr && rq->curr == p)
+               if (p->prio > rq->rt.highest_prio.curr)
                        resched_curr(rq);
 #else
                /* For UP simply resched on drop of prio */
@@ -2318,7 +2327,6 @@ const struct sched_class rt_sched_class = {
        .set_cpus_allowed       = set_cpus_allowed_rt,
        .rq_online              = rq_online_rt,
        .rq_offline             = rq_offline_rt,
-       .post_schedule          = post_schedule_rt,
        .task_woken             = task_woken_rt,
        .switched_from          = switched_from_rt,
 #endif