[RFC PATCH v4 23/28] sched/deadline: Fix HCBS migrations on server stop

[Yuri Andriaccio]

From: luca abeni <luca.abeni@xxxxxxxxxxxxxxx>

Do not unthrottle a non-fair-server dl_server_stop(), since it ends up
being stopped when throttled (we try to migrate all the RT tasks away
from it).

Notes:
This is a temporary workaround, but it will be hopefully removed in
favor of less invasive code.

Co-developed-by: Yuri Andriaccio <yurand2000@xxxxxxxxx>
Signed-off-by: Yuri Andriaccio <yurand2000@xxxxxxxxx>
Signed-off-by: luca abeni <luca.abeni@xxxxxxxxxxxxxxx>
---
 kernel/sched/deadline.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
index a588fe3bbf..91588f3d2e 100644
--- a/kernel/sched/deadline.c
+++ b/kernel/sched/deadline.c
@@ -1714,9 +1714,11 @@ void dl_server_stop(struct sched_dl_entity *dl_se)
 		return;

 	dequeue_dl_entity(dl_se, DEQUEUE_SLEEP);
-	hrtimer_try_to_cancel(&dl_se->dl_timer);
+	if (dl_se == &rq_of_dl_se(dl_se)->fair_server) {
+		hrtimer_try_to_cancel(&dl_se->dl_timer);
+		dl_se->dl_throttled = 0;
+	}
 	dl_se->dl_defer_armed = 0;
-	dl_se->dl_throttled = 0;
 	dl_se->dl_server_active = 0;
 }

--
2.51.0