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

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: 3960c8c0c789 ("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>

1 files changed, 2 insertions, 2 deletions

diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
index 5e2f99bd5ce0..9d3ad6433d88 100644
--- 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;
 }