From: "tj@kernel.org" <tj@kernel.org>
To: Ming Lei <ming.lei@redhat.com>
Cc: Bart Van Assche <Bart.VanAssche@wdc.com>,
"linux-block@vger.kernel.org" <linux-block@vger.kernel.org>,
"israelr@mellanox.com" <israelr@mellanox.com>,
"sagi@grimberg.me" <sagi@grimberg.me>, "hch@lst.de" <hch@lst.de>,
"stable@vger.kernel.org" <stable@vger.kernel.org>,
"axboe@kernel.dk" <axboe@kernel.dk>,
"maxg@mellanox.com" <maxg@mellanox.com>
Subject: Re: [PATCH v4] blk-mq: Fix race conditions in request timeout handling
Date: Tue, 10 Apr 2018 08:30:31 -0700 [thread overview]
Message-ID: <20180410153031.GO3126663@devbig577.frc2.facebook.com> (raw)
In-Reply-To: <20180410152553.GC22340@ming.t460p>
Hello, Ming.
On Tue, Apr 10, 2018 at 11:25:54PM +0800, Ming Lei wrote:
> + if (time_after_eq(jiffies, deadline) &&
> + blk_mq_change_rq_state(rq, MQ_RQ_IN_FLIGHT, MQ_RQ_COMPLETE)) {
> + blk_mq_rq_timed_out(rq, reserved);
>
> Normal completion still can happen between blk_mq_change_rq_state()
> and blk_mq_rq_timed_out().
>
> In tj's approach, there is synchronize_rcu() between writing aborted_gstate
> and blk_mq_rq_timed_out, it is easier for normal completion to happen during
> the big window.
I don't think plugging this hole is all that difficult, but this
shouldn't lead to any critical failures. If so, that'd be a driver
bug.
Thanks.
--
tejun
next prev parent reply other threads:[~2018-04-10 15:30 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-04-10 1:34 [PATCH v4] blk-mq: Fix race conditions in request timeout handling Bart Van Assche
2018-04-10 7:59 ` jianchao.wang
2018-04-10 10:04 ` Ming Lei
2018-04-10 12:04 ` Shan Hai
2018-04-10 13:01 ` Bart Van Assche
2018-04-10 14:32 ` jianchao.wang
2018-04-10 8:41 ` Ming Lei
2018-04-10 12:58 ` Bart Van Assche
2018-04-10 13:55 ` Ming Lei
2018-04-10 14:09 ` Bart Van Assche
2018-04-10 14:30 ` Ming Lei
2018-04-10 15:02 ` Bart Van Assche
2018-04-10 15:25 ` Ming Lei
2018-04-10 15:30 ` tj [this message]
2018-04-10 15:38 ` Ming Lei
2018-04-10 15:40 ` tj
2018-04-10 21:33 ` tj
2018-04-10 21:46 ` Bart Van Assche
2018-04-10 21:54 ` tj
2018-04-11 12:50 ` Bart Van Assche
2018-04-11 14:16 ` tj
2018-04-11 18:38 ` Martin Steigerwald
2018-04-11 14:24 ` Sagi Grimberg
2018-04-11 14:43 ` tj
2018-04-11 16:16 ` Israel Rukshin
2018-04-11 17:07 ` tj
2018-04-11 21:31 ` tj
2018-04-12 8:59 ` Israel Rukshin
2018-04-12 13:35 ` tj
2018-04-15 12:28 ` Israel Rukshin
2018-04-18 16:34 ` Bart Van Assche
2018-04-10 9:55 ` Christoph Hellwig
2018-04-10 13:26 ` Bart Van Assche
2018-04-10 14:50 ` hch
2018-04-10 14:41 ` Jens Axboe
2018-04-10 14:20 ` Tejun Heo
2018-04-10 14:30 ` Bart Van Assche
2018-04-10 14:33 ` tj
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