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-rw-r--r--kernel/sched/deadline.c34
1 files changed, 29 insertions, 5 deletions
diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
index 3862a28cd05d..6d93f4518734 100644
--- a/kernel/sched/deadline.c
+++ b/kernel/sched/deadline.c
@@ -1525,14 +1525,38 @@ static void enqueue_task_dl(struct rq *rq, struct task_struct *p, int flags)
*/
if (pi_task && dl_prio(pi_task->normal_prio) && p->dl.dl_boosted) {
pi_se = &pi_task->dl;
+ /*
+ * Because of delays in the detection of the overrun of a
+ * thread's runtime, it might be the case that a thread
+ * goes to sleep in a rt mutex with negative runtime. As
+ * a consequence, the thread will be throttled.
+ *
+ * While waiting for the mutex, this thread can also be
+ * boosted via PI, resulting in a thread that is throttled
+ * and boosted at the same time.
+ *
+ * In this case, the boost overrides the throttle.
+ */
+ if (p->dl.dl_throttled) {
+ /*
+ * The replenish timer needs to be canceled. No
+ * problem if it fires concurrently: boosted threads
+ * are ignored in dl_task_timer().
+ */
+ hrtimer_try_to_cancel(&p->dl.dl_timer);
+ p->dl.dl_throttled = 0;
+ }
} else if (!dl_prio(p->normal_prio)) {
/*
- * Special case in which we have a !SCHED_DEADLINE task
- * that is going to be deboosted, but exceeds its
- * runtime while doing so. No point in replenishing
- * it, as it's going to return back to its original
- * scheduling class after this.
+ * Special case in which we have a !SCHED_DEADLINE task that is going
+ * to be deboosted, but exceeds its runtime while doing so. No point in
+ * replenishing it, as it's going to return back to its original
+ * scheduling class after this. If it has been throttled, we need to
+ * clear the flag, otherwise the task may wake up as throttled after
+ * being boosted again with no means to replenish the runtime and clear
+ * the throttle.
*/
+ p->dl.dl_throttled = 0;
BUG_ON(!p->dl.dl_boosted || flags != ENQUEUE_REPLENISH);
return;
}