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Date: Thu, 12 Apr 2018 06:43:45 +0800
From: Ming Lei <ming.lei@redhat.com>
To: Tejun Heo <tj@kernel.org>
Cc: Jens Axboe <axboe@kernel.dk>, linux-block@vger.kernel.org,
        Bart Van Assche <bart.vanassche@wdc.com>,
        Christoph Hellwig <hch@lst.de>,
        Sagi Grimberg <sagi@grimberg.me>,
        Israel Rukshin <israelr@mellanox.com>,
        Max Gurtovoy <maxg@mellanox.com>, stable@vger.kernel.org
Subject: Re: [PATCH] blk-mq: fix race between complete and BLK_EH_RESET_TIMER
Message-ID: <20180411224344.GA31433@ming.t460p>
References: <20180411205529.31145-1-ming.lei@redhat.com>
 <20180411213007.GR793541@devbig577.frc2.facebook.com>
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On Wed, Apr 11, 2018 at 02:30:07PM -0700, Tejun Heo wrote:
> Hello, Ming.
> 
> On Thu, Apr 12, 2018 at 04:55:29AM +0800, Ming Lei wrote:
> ...
> > +		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);
> 
> Nothing prevents the above blk_add_timer() racing against the next
> recycle instance of the request, so this still leaves a small race
> window.

OK.

But this small race window can be avoided by running blk_add_timer(req)
before blk_mq_rq_update_aborted_gstate(req, 0), can't it?

-- 
Ming