From: Tejun Heo <tj@kernel.org>
To: Akinobu Mita <akinobu.mita@gmail.com>
Cc: linux-kernel@vger.kernel.org, Jens Axboe <axboe@kernel.dk>,
Ming Lei <tom.leiming@gmail.com>, Christoph Hellwig <hch@lst.de>
Subject: Re: [PATCH v4 6/7] blk-mq: fix freeze queue race
Date: Sat, 26 Sep 2015 13:32:56 -0400 [thread overview]
Message-ID: <20150926173256.GA3572@htj.duckdns.org> (raw)
In-Reply-To: <1443287365-4244-7-git-send-email-akinobu.mita@gmail.com>
Hello,
On Sun, Sep 27, 2015 at 02:09:24AM +0900, Akinobu Mita wrote:
> @@ -420,7 +420,9 @@ static void blk_mq_sysfs_init(struct request_queue *q)
> /* see blk_register_queue() */
> void blk_mq_finish_init(struct request_queue *q)
> {
> + mutex_lock(&q->mq_freeze_lock);
> percpu_ref_switch_to_percpu(&q->mq_usage_counter);
> + mutex_unlock(&q->mq_freeze_lock);
This looks weird to me. What can it race against at this point?
> @@ -115,11 +115,15 @@ void blk_mq_freeze_queue_start(struct request_queue *q)
> {
> int freeze_depth;
>
> + mutex_lock(&q->mq_freeze_lock);
> +
> freeze_depth = atomic_inc_return(&q->mq_freeze_depth);
It doesn't have to be an atomic anymore, right?
Thanks.
--
tejun
next prev parent reply other threads:[~2015-09-26 17:33 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-09-26 17:09 [PATCH v4 0/7] blk-mq: fix race conditions on cpu hotplug handling Akinobu Mita
2015-09-26 17:09 ` [PATCH v4 1/7] blk-mq: avoid setting hctx->tags->cpumask before allocation Akinobu Mita
2015-09-26 18:12 ` Christoph Hellwig
2015-09-26 17:09 ` [PATCH v4 2/7] blk-mq: fix sysfs registration/unregistration race Akinobu Mita
2015-09-29 6:51 ` Christoph Hellwig
2015-09-26 17:09 ` [PATCH v4 3/7] blk-mq: Fix use after of free q->mq_map Akinobu Mita
2015-09-29 6:52 ` Christoph Hellwig
2015-10-05 23:50 ` Akinobu Mita
2015-10-06 9:43 ` Christoph Hellwig
2015-09-26 17:09 ` [PATCH v4 4/7] blk-mq: fix q->mq_usage_counter access race Akinobu Mita
2015-09-29 6:53 ` Christoph Hellwig
2015-09-26 17:09 ` [PATCH v4 5/7] blk-mq: avoid inserting requests before establishing new mapping Akinobu Mita
2015-09-29 6:54 ` Christoph Hellwig
2015-09-26 17:09 ` [PATCH v4 6/7] blk-mq: fix freeze queue race Akinobu Mita
2015-09-26 17:32 ` Tejun Heo [this message]
2015-09-27 13:06 ` Akinobu Mita
2015-09-28 14:48 ` Tejun Heo
2015-09-29 6:55 ` Christoph Hellwig
2015-09-29 15:01 ` Jens Axboe
2015-09-29 15:03 ` Tejun Heo
2015-09-29 21:50 ` Tejun Heo
2015-09-30 10:32 ` Akinobu Mita
2015-09-26 17:09 ` [PATCH v4 7/7] blk-mq: fix deadlock when reading cpu_list Akinobu Mita
2015-09-29 6:58 ` Christoph Hellwig
2015-09-29 17:31 ` [PATCH v4 0/7] blk-mq: fix race conditions on cpu hotplug handling Jens Axboe
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