From: Tejun Heo <tj@kernel.org>
To: Bart Van Assche <bvanassche@acm.org>
Cc: linux-scsi <linux-scsi@vger.kernel.org>,
James Bottomley <jbottomley@parallels.com>,
Mike Christie <michaelc@cs.wisc.edu>,
Jens Axboe <axboe@kernel.dk>, Chanho Min <chanho.min@lge.com>
Subject: Re: [PATCH 4/4] Fix race between starved list processing and device removal
Date: Tue, 16 Oct 2012 16:59:14 -0700 [thread overview]
Message-ID: <20121016235914.GM16166@google.com> (raw)
In-Reply-To: <50758FEB.9090602@acm.org>
Hello,
On Wed, Oct 10, 2012 at 05:10:35PM +0200, Bart Van Assche wrote:
> Avoid that the sdev reference count can drop to zero before
> the queue is run by scsi_run_queue(). Also avoid that the sdev
> reference count can drop to zero in the same function by invoking
> __blk_run_queue().
I think this is correct but again had to scratch my head quite a bit.
It would be nice to start with brief explanation of starved_list,
especially the way it's processed per-host instead of per-device. And
then explain how it's broken(how nothing guarantees a device to be
alive while on starved_list) and the fix.
Thanks.
--
tejun
prev parent reply other threads:[~2012-10-16 23:59 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-10-10 15:05 [PATCH 0/4 v4] More device removal fixes Bart Van Assche
2012-10-10 15:07 ` [PATCH 1/4] block: Rename queue dead flag Bart Van Assche
2012-10-16 23:31 ` Tejun Heo
2012-10-10 15:08 ` [PATCH 2/4] block: Avoid that request_fn is invoked on a dead queue Bart Van Assche
2012-10-16 23:38 ` Tejun Heo
2012-10-23 12:11 ` Bart Van Assche
2012-10-24 19:13 ` Tejun Heo
2012-10-10 15:09 ` [PATCH 3/4] Make blk_cleanup_queue() wait until request_fn finished Bart Van Assche
2012-10-16 23:51 ` Tejun Heo
2012-10-23 12:16 ` Bart Van Assche
2012-10-24 19:11 ` Tejun Heo
2012-10-10 15:10 ` [PATCH 4/4] Fix race between starved list processing and device removal Bart Van Assche
2012-10-16 23:59 ` Tejun Heo [this message]
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