For whatever reason, if start_dl_timer() returned 0 during replenish (it
did not start a new timer), then do not marked dl_defer_armed, because
we never really armed.
Further, we need to cancel any old timers,
This is similar to what dl_check_constrained_dl() does.
Add some guardrails for such situations.
Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
---
kernel/sched/deadline.c | 20 ++++++++++++++++++--
1 file changed, 18 insertions(+), 2 deletions(-)
diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
index dbba95d364e2..e978e299381c 100644
--- a/kernel/sched/deadline.c
+++ b/kernel/sched/deadline.c
@@ -918,7 +918,16 @@ static void replenish_dl_entity(struct sched_dl_entity *dl_se)
if (!is_dl_boosted(dl_se)) {
dl_se->dl_defer_armed = 1;
dl_se->dl_throttled = 1;
- start_dl_timer(dl_se);
+ if (!start_dl_timer(dl_se)) {
+ /*
+ * If for whatever reason (delays), if a previous timer was
+ * queued but not serviced, cancel it.
+ */
+ hrtimer_try_to_cancel(&dl_se->dl_timer);
+ dl_se->dl_defer_armed = 0;
+ dl_se->dl_throttled = 0;
+ return;
+ }
}
}
}
@@ -1465,7 +1474,14 @@ static void update_curr_dl_se(struct rq *rq, struct sched_dl_entity *dl_se, s64
hrtimer_try_to_cancel(&dl_se->dl_timer);
replenish_dl_new_period(dl_se, dl_se->rq);
- start_dl_timer(dl_se);
+
+ /*
+ * Not being able to start the timer seems problematic. If it could not
+ * be started for whatever reason, we need to "unthrottle" the DL server
+ * and queue right away. Otherwise nothing might queue it. That's similar
+ * to what enqueue_dl_entity() does on start_dl_timer==0. For now, just warn.
+ */
+ WARN_ON_ONCE(!start_dl_timer(dl_se));
return;
}
--
2.34.1