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SubjectRe: [PATCH v2 7/7] sched/rt: reschedule if stop/dl task slip in after pull operations
On Wed, May 13, 2015 at 02:01:07PM +0800, Wanpeng Li wrote:
> pull_rt_task() can drop (and re-acquire) rq->lock, this means a dl
> or stop task can slip in, in which case need to reschedule. This
> patch add the reschedule when the scenario occurs.
>
> Signed-off-by: Wanpeng Li <wanpeng.li@linux.intel.com>
> ---
> kernel/sched/rt.c | 19 ++++++++++++++++++-
> 1 file changed, 18 insertions(+), 1 deletion(-)
>
> diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c
> index 560d2fa..8c948bf 100644
> --- a/kernel/sched/rt.c
> +++ b/kernel/sched/rt.c
> @@ -2136,7 +2136,14 @@ static void switched_from_rt(struct rq *rq, struct task_struct *p)
> if (!task_on_rq_queued(p) || rq->rt.rt_nr_running)
> return;
>
> - if (pull_rt_task(rq))
> + /*
> + * pull_rt_task() can drop (and re-acquire) rq->lock; this
> + * means a dl or stop task can slip in, in which case we need
> + * to reschedule.
> + */
> + if (pull_rt_task(rq) ||
> + (unlikely((rq->stop && task_on_rq_queued(rq->stop)) ||
> + rq->dl.dl_nr_running)))
> resched_curr(rq);
> }

Same as before; why is the normal wakeup preemption check not working?


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