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From: Bart Van Assche <bvanassche@acm.org>
To: Tejun Heo <tj@kernel.org>
Cc: Mike Christie <michaelc@cs.wisc.edu>,
	linux-scsi <linux-scsi@vger.kernel.org>,
	James Bottomley <jbottomley@parallels.com>,
	Jens Axboe <axboe@kernel.dk>, Chanho Min <chanho.min@lge.com>
Subject: Re: [PATCH] Fix a use-after-free triggered by device removal
Date: Fri, 07 Sep 2012 08:57:10 +0200	[thread overview]
Message-ID: <50499AC6.1050008@acm.org> (raw)
In-Reply-To: <20120906232031.GU29092@google.com>

On 09/07/12 01:20, Tejun Heo wrote:
> I think Mike is wondering whether your patch in isolation is enough or
> we also need to have DEAD check there too.  The proposed patch can't
> handle the case where q->request_fn() is invoked after drain is
> complete.  I'm not really sure whether that can happen tho.

Hello Tejun,

I'm not sure it would be a good idea to add a blk_queue_dead() check in
any of the __blk_run_queue() variants since blk_drain_queue() can invoke
__blk_run_queue() to drain the queue.

Also, as far as I can see the functions that can insert a request into
the queue (blk_insert_cloned_request(), queue_unplugged(),
blk_execute_rq_nowait()) all check whether the queue is dead before
inserting a request. That should be sufficient to prevent that new
requests are queued after QUEUE_FLAG_DEAD has been set.

Bart.


  reply	other threads:[~2012-09-07  6:57 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-09-03 14:12 [PATCH] Fix a use-after-free triggered by device removal Bart Van Assche
2012-09-06 16:27 ` Michael Christie
2012-09-06 17:58   ` Bart Van Assche
2012-09-06 18:14     ` Mike Christie
2012-09-06 18:52       ` Bart Van Assche
2012-09-06 23:20         ` Tejun Heo
2012-09-07  6:57           ` Bart Van Assche [this message]
2012-09-10 23:38             ` Tejun Heo
2012-09-11  6:42               ` Bart Van Assche
2012-09-12 20:53                 ` Tejun Heo
2012-09-13  7:26                   ` Bart Van Assche
2012-09-13 16:53                     ` Tejun Heo
2012-09-13 18:27                       ` Bart Van Assche
2012-09-13 19:25                         ` Tejun Heo

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