1 files changed, 32 insertions, 9 deletions

diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
index 256e577faf1b..5285332392d5 100644
--- a/kernel/sched/deadline.c
+++ b/kernel/sched/deadline.c
@@ -518,12 +518,20 @@ again:
         }
 
         /*
-         * We need to take care of a possible races here. In fact, the
-         * task might have changed its scheduling policy to something
-         * different from SCHED_DEADLINE or changed its reservation
-         * parameters (through sched_setattr()).
+         * We need to take care of several possible races here:
+         *
+         *   - the task might have changed its scheduling policy
+         *     to something different than SCHED_DEADLINE
+         *   - the task might have changed its reservation parameters
+         *     (through sched_setattr())
+         *   - the task might have been boosted by someone else and
+         *     might be in the boosting/deboosting path
+         *
+         * In all this cases we bail out, as the task is already
+         * in the runqueue or is going to be enqueued back anyway.
          */
-        if (!dl_task(p) || dl_se->dl_new)
+        if (!dl_task(p) || dl_se->dl_new ||
+            dl_se->dl_boosted || !dl_se->dl_throttled)
                 goto unlock;
 
         sched_clock_tick();
@@ -532,7 +540,7 @@ again:
         dl_se->dl_yielded = 0;
         if (task_on_rq_queued(p)) {
                 enqueue_task_dl(rq, p, ENQUEUE_REPLENISH);
-                if (task_has_dl_policy(rq->curr))
+                if (dl_task(rq->curr))
                         check_preempt_curr_dl(rq, p, 0);
                 else
                         resched_curr(rq);
@@ -847,8 +855,19 @@ static void enqueue_task_dl(struct rq *rq, struct task_struct *p, int flags)
          * smaller than our one... OTW we keep our runtime and
          * deadline.
          */
-        if (pi_task && p->dl.dl_boosted && dl_prio(pi_task->normal_prio))
+        if (pi_task && p->dl.dl_boosted && dl_prio(pi_task->normal_prio)) {
                 pi_se = &pi_task->dl;
+        } else if (!dl_prio(p->normal_prio)) {
+                /*
+                 * Special case in which we have a !SCHED_DEADLINE task
+                 * that is going to be deboosted, but exceedes its
+                 * runtime while doing so. No point in replenishing
+                 * it, as it's going to return back to its original
+                 * scheduling class after this.
+                 */
+                BUG_ON(!p->dl.dl_boosted || flags != ENQUEUE_REPLENISH);
+                return;
+        }
 
         /*
          * If p is throttled, we do nothing. In fact, if it exhausted
@@ -1607,8 +1626,12 @@ static void switched_to_dl(struct rq *rq, struct task_struct *p)
                         /* Only reschedule if pushing failed */
                         check_resched = 0;
 #endif /* CONFIG_SMP */
-                if (check_resched && task_has_dl_policy(rq->curr))
-                        check_preempt_curr_dl(rq, p, 0);
+                if (check_resched) {
+                        if (dl_task(rq->curr))
+                                check_preempt_curr_dl(rq, p, 0);
+                        else
+                                resched_curr(rq);
+                }
         }
 }