On Wed, 2018-09-19 at 10:21 +0800, jianchao.wang wrote:
> On 09/19/2018 01:44 AM, Bart Van Assche wrote:
> > There is only one blk_pm_request_resume() call and that call is
> > inside blk_queue_enter() after the pm_only counter has been
> > checked.
> >
> > For the legacy block layer, nr_pending is increased after the
> > blk_queue_enter() call from inside blk_old_get_request() succeeded.
> >
> > So I don't see how blk_pm_request_resume() or q->nr_pending++ could
> > escape from the preempt checking?
>
> For example:
>
>
> blk_pre_runtime_suspend generic_make_request
> blk_queue_enter //
> success here, no blk_pm_request_resume here
> blk_mq_make_requset
> blk_set_pm_only
>
> if (blk_requests_in_flight(q) == 0) {
> synchronize_rcu();
> if (blk_requests_in_flight(q) == 0)
> ret = 0;
> }
> blk_mq_get_request
Hello Jianchao,
I think you are right. I will add a q_usage_counter check before
setting 'ret' to zero.
Bart.
