Re: [PATCH 6/6] blk-mq: remove REQ_ATOM_STARTED

Tejun Heo
2017-12-12T17:26:35Z

Hello, again.

Sorry, I missed part of your comment in the previous reply.

On Tue, Dec 12, 2017 at 06:09:32PM +0800, jianchao.wang wrote:
> > static void __blk_mq_requeue_request(struct request *rq)
> > {
> > @@ -679,7 +672,7 @@ static void __blk_mq_requeue_request(struct request *rq)
> > wbt_requeue(q->rq_wb, &rq->issue_stat);
> > blk_mq_sched_requeue_request(rq);
> >
> > - if (test_and_clear_bit(REQ_ATOM_STARTED, &rq->atomic_flags)) {
> > + if (blk_mq_rq_state(rq) != MQ_RQ_IDLE) {
> > blk_mq_rq_update_state(rq, MQ_RQ_IDLE);
>
> The MQ_RQ_IDLE looks confused here. It is not freed , but idled.
> And when the requeued request is started again, the generation
> number will be increased. But it is not a recycle instance of the
> request. Maybe another state needed here ?

I don't quite follow it. At this point, the request can't be
in-flight on the device side and is scheduled for re-submission. I'm
not sure the distinction from IDLE is necessary. Am I missing
something?

Thanks.

--
tejun