From: Stefan Richter <stefanr@s5r6.in-berlin.de>
To: Bart Van Assche <bvanassche@acm.org>
Cc: Jun'ichi Nomura <j-nomura@ce.jp.nec.com>,
jbottomley@parallels.com, linux-scsi@vger.kernel.org,
Huajun Li <huajun.li.lee@gmail.com>,
Axel Theilmann <theilmann@pre-sense.de>,
linux-kernel@vger.kernel.org
Subject: Re: Yet another hot unplug NULL pointer dereference (was Re: status of oops in sd_revalidate_disk?)
Date: Tue, 14 Feb 2012 14:38:00 +0100 [thread overview]
Message-ID: <20120214143800.69703df9@stein> (raw)
In-Reply-To: <CAO+b5-pCW-F1nD365TnEiAfoN7zKB4zXkk3uO6p5QyUPY2icsA@mail.gmail.com>
On Feb 14 Bart Van Assche wrote:
> On Tue, Feb 14, 2012 at 12:34 PM, Jun'ichi Nomura
> <j-nomura@ce.jp.nec.com> wrote:
> > While scsi_device is propery refcounted object,
> > q->queuedata is set to NULL by scsi_remove_device() asynchronously.
> > So every reader of scsi_device's q->queuedata should always check it.
>
> As far as I can see this patch narrows the race window but doesn't fix
> the race. At least sd_prep_fn() still reads queuedata and if I'm not
> mistaken that read races with scsi_remove_device(). Has it been
> considered to modify scsi_remove_device() and scsi_request_fn() such
> that device removal is communicated from the former to the latter in
> another way than by clearing queuedata ?
Or asked differently, *what* is supposed to serialize the ->queuedata
accesses?
(If it is the BKL -- well, some bleeding edge kernel versions lack it,
sources say.)
--
Stefan Richter
-=====-===-- --=- -===-
http://arcgraph.de/sr/
next prev parent reply other threads:[~2012-02-14 13:38 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-12-14 17:59 status of oops in sd_revalidate_disk? Axel Theilmann
2011-12-21 14:12 ` Huajun Li
2011-12-25 20:58 ` Yet another hot unplug NULL pointer dereference (was Re: status of oops in sd_revalidate_disk?) Stefan Richter
2011-12-27 10:21 ` Axel Theilmann
2011-12-27 10:21 ` Axel Theilmann
2011-12-27 13:40 ` Stefan Richter
2012-02-14 11:34 ` Jun'ichi Nomura
2012-02-14 11:54 ` Bart Van Assche
2012-02-14 13:38 ` Stefan Richter [this message]
2012-02-14 19:11 ` Bart Van Assche
2012-02-15 2:26 ` Jun'ichi Nomura
2012-02-15 11:29 ` Bart Van Assche
2012-02-16 1:04 ` Jun'ichi Nomura
2012-03-13 18:10 ` Bart Van Assche
2012-03-16 8:58 ` Jun'ichi Nomura
2012-03-16 18:53 ` Bart Van Assche
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