sched/deadline: Always enqueue on previous rq when dl_task_timer() fires

Juri Lelli · Ingo Molnar · commit 4cd57f971358 · 2015-04-02T17:42:56.000+02:00
dl_task_timer() may fire on a different rq from where a task was removed after throttling. Since the call path is: dl_task_timer() -> enqueue_task_dl() -> enqueue_dl_entity() -> replenish_dl_entity() and replenish_dl_entity() uses dl_se's rq, we can't use current's rq in dl_task_timer(), but we need to lock the task's previous one. Tested-by: Wanpeng Li <wanpeng.li@linux.intel.com> Signed-off-by: Juri Lelli <juri.lelli@arm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Kirill Tkhai <ktkhai@parallels.com> Cc: Juri Lelli <juri.lelli@gmail.com> Fixes: 3960c8c ("sched: Make dl_task_time() use task_rq_lock()") Link: http://lkml.kernel.org/r/1427792017-7356-1-git-send-email-juri.lelli@arm.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
@@ -514,7 +514,7 @@ static enum hrtimer_restart dl_task_timer(struct hrtimer *timer)
 	unsigned long flags;
 	struct rq *rq;
 
-	rq = task_rq_lock(current, &flags);
+	rq = task_rq_lock(p, &flags);
 
 	/*
 	 * We need to take care of several possible races here:
@@ -569,7 +569,7 @@ static enum hrtimer_restart dl_task_timer(struct hrtimer *timer)
 		push_dl_task(rq);
 #endif
 unlock:
-	task_rq_unlock(rq, current, &flags);
+	task_rq_unlock(rq, p, &flags);
 
 	return HRTIMER_NORESTART;
 }
