On 5/29/15 10:16 PM, Peter Zijlstra wrote:
On Wed, May 13, 2015 at 02:01:04PM +0800, Wanpeng Li wrote:
pull_dl_task can drop (and re-acquire) rq->lock, this means a stop task
can slip in, in which case we need to reschedule. This patch add the
reschedule when the scenario occurs.
Signed-off-by: Wanpeng Li <wanpeng...@linux.intel.com>
---
kernel/sched/deadline.c | 16 +++++++++++++++-
1 file changed, 15 insertions(+), 1 deletion(-)
diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
index e49b1e6..7d4c4fc 100644
--- a/kernel/sched/deadline.c
+++ b/kernel/sched/deadline.c
@@ -1750,7 +1750,13 @@ static void switched_from_dl(struct rq *rq, struct
task_struct *p)
if (!task_on_rq_queued(p) || rq->dl.dl_nr_running)
return;
- if (pull_dl_task(rq))
+ /*
+ * pull_dl_task() can drop (and re-acquire) rq->lock; this
+ * means a stop task can slip in, in which case we need to
+ * reschedule.
+ */
+ if (pull_dl_task(rq) ||
+ (rq->stop && task_on_rq_queued(rq->stop)))
resched_curr(rq);
But, the waking of the stop task will already have done the preemption
check and won (obviously). So the wakeup should already have done the
resched_curr().
Indeed, thanks for your pointing out. :)
So why?
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