From: Bart Van Assche <Bart.VanAssche@sandisk.com>
To: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"hch@infradead.org" <hch@infradead.org>,
"linux-block@vger.kernel.org" <linux-block@vger.kernel.org>,
"tom.leiming@gmail.com" <tom.leiming@gmail.com>,
"axboe@fb.com" <axboe@fb.com>
Cc: "yizhan@redhat.com" <yizhan@redhat.com>,
"stable@vger.kernel.org" <stable@vger.kernel.org>
Subject: Re: [PATCH 1/2] blk-mq: don't complete un-started request in timeout handler
Date: Wed, 15 Mar 2017 00:07:37 +0000 [thread overview]
Message-ID: <1489536441.2676.21.camel@sandisk.com> (raw)
In-Reply-To: <1489064578-17305-3-git-send-email-tom.leiming@gmail.com>
On Thu, 2017-03-09 at 21:02 +0800, Ming Lei wrote:
> diff --git a/block/blk-mq.c b/block/blk-mq.c
> index 159187a28d66..0aff380099d5 100644
> --- a/block/blk-mq.c
> +++ b/block/blk-mq.c
> @@ -697,17 +697,8 @@ static void blk_mq_check_expired(struct blk_mq_hw_ct=
x *hctx,
> {
> struct blk_mq_timeout_data *data =3D priv;
> =20
> - if (!test_bit(REQ_ATOM_STARTED, &rq->atomic_flags)) {
> - /*
> - * If a request wasn't started before the queue was
> - * marked dying, kill it here or it'll go unnoticed.
> - */
> - if (unlikely(blk_queue_dying(rq->q))) {
> - rq->errors =3D -EIO;
> - blk_mq_end_request(rq, rq->errors);
> - }
> + if (!test_bit(REQ_ATOM_STARTED, &rq->atomic_flags))
> return;
> - }
> =20
> if (time_after_eq(jiffies, rq->deadline)) {
> if (!blk_mark_rq_complete(rq))
Both the old and the new check look racy to me. The REQ_ATOM_STARTED bit ca=
n
be changed concurrently by blk_mq_start_request(), __blk_mq_finish_request(=
)
or __blk_mq_requeue_request(). Another issue with this function is that the
request passed to this function can be reinitialized concurrently. Sorry bu=
t
I'm not sure what the best way is to address these issues.
Bart.=
next prev parent reply other threads:[~2017-03-15 0:08 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-03-09 13:02 [PATCH 0/2] blk-mq: dying queue fix & improvement Ming Lei
2017-03-09 13:02 ` Ming Lei
2017-03-09 13:02 ` [PATCH 1/2] blk-mq: don't complete un-started request in timeout handler Ming Lei
2017-03-15 0:07 ` Bart Van Assche [this message]
2017-03-15 12:18 ` Ming Lei
2017-03-15 12:40 ` Ming Lei
2017-03-15 15:36 ` Bart Van Assche
2017-03-15 16:22 ` Ming Lei
2017-03-15 16:46 ` Ming Lei
2017-03-15 21:35 ` Bart Van Assche
2017-03-16 0:07 ` Ming Lei
2017-03-16 21:35 ` Bart Van Assche
2017-03-17 0:07 ` Ming Lei
2017-03-15 21:34 ` Bart Van Assche
2017-03-15 23:41 ` Ming Lei
2017-03-15 14:11 ` Yi Zhang
2017-03-16 21:37 ` Bart Van Assche
2017-03-09 13:02 ` [PATCH 2/2] blk-mq: start to freeze queue just after setting dying Ming Lei
2017-03-09 16:58 ` Bart Van Assche
2017-03-10 2:16 ` Ming Lei
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