From: Christoph Hellwig <hch@lst.de>
To: Tejun Heo <tj@kernel.org>
Cc: Akinobu Mita <akinobu.mita@gmail.com>,
LKML <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: Tue, 29 Sep 2015 08:55:56 +0200 [thread overview]
Message-ID: <20150929065556.GE14911@lst.de> (raw)
In-Reply-To: <20150928144839.GA2589@mtj.duckdns.org>
On Mon, Sep 28, 2015 at 10:48:39AM -0400, Tejun Heo wrote:
> Ah, you're right. I was thinking that percpu_ref_switch_to_percpu()
> being called after blk_mq_freeze_queue_start() would be buggy and thus
> the above can't be enough but that is safe as long as the calls are
> properly synchronized. Hmmm... maybe we should add synchronization to
> those operations from percpu_ref side.
I think that would be very useful, as most users of the code will
have similar issues.
next prev parent reply other threads:[~2015-09-29 6:56 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
2015-09-27 13:06 ` Akinobu Mita
2015-09-28 14:48 ` Tejun Heo
2015-09-29 6:55 ` Christoph Hellwig [this message]
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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