[PATCH] sched/deadline: Zero out positive runtime after throttling constrained tasks

[Xunlei Pang <xlpang@redhat.com>]

When a contrained task is throttled by dl_check_constrained_dl(),
it may carry the remaining positive runtime, as a result when
dl_task_timer() fires and calls replenish_dl_entity(), it will
not be replenished correctly due to the positive dl_se->runtime.

This patch assigns its runtime to 0 if positive after throttling.

Fixes: df8eac8cafce ("sched/deadline: Throttle a constrained deadline task activated after the deadline)
Cc: Daniel Bristot de Oliveira <bristot@redhat.com>
Signed-off-by: Xunlei Pang <xlpang@redhat.com>
---
 kernel/sched/deadline.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
index a2ce590..d3d291e 100644
--- a/kernel/sched/deadline.c
+++ b/kernel/sched/deadline.c
@@ -723,6 +723,8 @@ static inline void dl_check_constrained_dl(struct sched_dl_entity *dl_se)
 		if (unlikely(dl_se->dl_boosted || !start_dl_timer(p)))
 			return;
 		dl_se->dl_throttled = 1;
+		if (dl_se->runtime > 0)
+			dl_se->runtime = 0;
 	}
 }
 
-- 
1.8.3.1