From: Jens Axboe <axboe@kernel.dk>
To: Ming Lei <tom.leiming@gmail.com>, linux-kernel@vger.kernel.org
Cc: Rusty Russell <rusty@rustcorp.com.au>
Subject: Re: [PATCH] virtio_blk: fix race between start and stop queue
Date: Fri, 16 May 2014 08:53:22 -0600 [thread overview]
Message-ID: <53762662.2050702@kernel.dk> (raw)
In-Reply-To: <1400157181-17800-1-git-send-email-tom.leiming@gmail.com>
On 2014-05-15 06:33, Ming Lei wrote:
> When there isn't enough vring descriptor for adding to vq,
> blk-mq will be put as stopped state until some of pending
> descriptors are completed & freed.
>
> Unfortunately, the vq's interrupt may come just before
> blk-mq's BLK_MQ_S_STOPPED flag is set, so the blk-mq will
> still be kept as stopped even though lots of descriptors
> are completed and freed in the interrupt handler. The worst
> case is that all pending descriptors are freed in the
> interrupt handler, and the queue is kept as stopped forever.
>
> This patch fixes the problem by starting/stopping blk-mq
> with holding vq_lock.
Why not just use blk_mq_start_hw_queues()?
--
Jens Axboe
next prev parent reply other threads:[~2014-05-16 14:53 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-05-15 12:33 [PATCH] virtio_blk: fix race between start and stop queue Ming Lei
2014-05-16 1:59 ` Rusty Russell
2014-05-19 0:26 ` Ming Lei
2014-05-16 14:53 ` Jens Axboe [this message]
2014-05-16 14:54 ` Christoph Hellwig
2014-05-16 14:58 ` Jens Axboe
2014-05-16 14:57 ` Jens Axboe
2014-05-16 15:15 ` Ming Lei
2014-05-16 15:17 ` Jens Axboe
2014-05-16 15:22 ` Ming Lei
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