2 files changed, 21 insertions, 0 deletions

diff --git a/kernel/sched.c b/kernel/sched.c
index 9dd8d121eea6..6185fa080ec8 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -343,6 +343,8 @@ struct rt_rq {
         int rt_load_balance_idx;
         struct list_head *rt_load_balance_head, *rt_load_balance_curr;
         unsigned long rt_nr_running;
+        /* highest queued rt task prio */
+        int highest_prio;
 };
 
 /*
@@ -6864,6 +6866,7 @@ void __init sched_init(void)
                 rq->cpu = i;
                 rq->migration_thread = NULL;
                 INIT_LIST_HEAD(&rq->migration_queue);
+                rq->rt.highest_prio = MAX_RT_PRIO;
 #endif
                 atomic_set(&rq->nr_iowait, 0);
 
diff --git a/kernel/sched_rt.c b/kernel/sched_rt.c
index e3d2ca8832af..136c2857a049 100644
--- a/kernel/sched_rt.c
+++ b/kernel/sched_rt.c
@@ -30,6 +30,10 @@ static inline void inc_rt_tasks(struct task_struct *p, struct rq *rq)
 {
         WARN_ON(!rt_task(p));
         rq->rt.rt_nr_running++;
+#ifdef CONFIG_SMP
+        if (p->prio < rq->rt.highest_prio)
+                rq->rt.highest_prio = p->prio;
+#endif /* CONFIG_SMP */
 }
 
 static inline void dec_rt_tasks(struct task_struct *p, struct rq *rq)
@@ -37,6 +41,20 @@ static inline void dec_rt_tasks(struct task_struct *p, struct rq *rq)
         WARN_ON(!rt_task(p));
         WARN_ON(!rq->rt.rt_nr_running);
         rq->rt.rt_nr_running--;
+#ifdef CONFIG_SMP
+        if (rq->rt.rt_nr_running) {
+                struct rt_prio_array *array;
+
+                WARN_ON(p->prio < rq->rt.highest_prio);
+                if (p->prio == rq->rt.highest_prio) {
+                        /* recalculate */
+                        array = &rq->rt.active;
+                        rq->rt.highest_prio =
+                                sched_find_first_bit(array->bitmap);
+                } /* otherwise leave rq->highest prio alone */
+        } else
+                rq->rt.highest_prio = MAX_RT_PRIO;
+#endif /* CONFIG_SMP */
 }
 
 static void enqueue_task_rt(struct rq *rq, struct task_struct *p, int wakeup)