Re: [PATCH] blk-mq: fix race between complete and BLK_EH_RESET_TIMER

[Ming Lei <ming.lei@redhat.com>]

On Wed, Apr 11, 2018 at 10:49:51PM +0000, Bart Van Assche wrote:
> On Thu, 2018-04-12 at 04:55 +0800, Ming Lei wrote:
> > +again:
> >  	switch (ret) {
> >  	case BLK_EH_HANDLED:
> >  		__blk_mq_complete_request(req);
> >  		break;
> >  	case BLK_EH_RESET_TIMER:
> >  		[ ... ]
> > +		spin_lock_irqsave(req->q->queue_lock, flags);
> > +		if (blk_mq_rq_state(req) != MQ_RQ_COMPLETE_IN_RESET) {
> > +			blk_mq_rq_update_aborted_gstate(req, 0);
> > +			blk_add_timer(req);
> > +		} else {
> > +			blk_mq_rq_update_state(req, MQ_RQ_IN_FLIGHT);
> > +			ret = BLK_EH_HANDLED;
> > +			goto again;
> > +		}
> > +		spin_unlock_irqrestore(req->q->queue_lock, flags);
> 
> Does the above chunk introduce a backwards goto from inside a region around
> which a spinlock is held to outside that region? Can such a goto result in
> anything else than a deadlock?

Yes, it is being fixed in my local V2, :-)

-- 
Ming