From: Xunlei Pang <xlpang@redhat.com>
Date: Wed, 10 May 2017 13:03:37 +0000 (+0800)
Subject: sched/deadline: Zero out positive runtime after throttling constrained tasks
X-Git-Tag: v4.4.113~26
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=8bd58b61d2faacdacd05287a3bbb32ad226b5428;p=thirdparty%2Fkernel%2Fstable.git

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

commit ae83b56a56f8d9643dedbee86b457fa1c5d42f59 upstream.

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.

Signed-off-by: Xunlei Pang <xlpang@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Daniel Bristot de Oliveira <bristot@redhat.com>
Cc: Juri Lelli <juri.lelli@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Luca Abeni <luca.abeni@santannapisa.it>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: df8eac8cafce ("sched/deadline: Throttle a constrained deadline task activated after the deadline)
Link: http://lkml.kernel.org/r/1494421417-27550-1-git-send-email-xlpang@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Ben Hutchings <ben.hutchings@codethink.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
index a996f73562162..6be2afd9bfd60 100644
--- a/kernel/sched/deadline.c
+++ b/kernel/sched/deadline.c
@@ -732,6 +732,8 @@ 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;
 	}
 }