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From: Tejun Heo <tj@kernel.org>
To: Bart Van Assche <bvanassche@acm.org>
Cc: Jens Axboe <axboe@kernel.dk>,
	Stanislaw Gruszka <sgruszka@redhat.com>,
	linux-scsi <linux-scsi@vger.kernel.org>
Subject: Re: [PATCH] block: Make blk_drain_queue() work for stopped queues
Date: Mon, 19 Mar 2012 10:04:35 -0700	[thread overview]
Message-ID: <20120319170435.GH11069@google.com> (raw)
In-Reply-To: <4F663BE3.4000503@acm.org>

Hello,

On Sun, Mar 18, 2012 at 07:47:47PM +0000, Bart Van Assche wrote:
> Not servicing queued SCSI requests can e.g. cause user space processes
> to hang. See also http://lkml.org/lkml/2011/8/27/6 for an example. Hence
> commit 3308511c93e6ad0d3c58984ecd6e5e57f96b12c8 which causes pending
> SCSI commands to be killed just before blk_cleanup_queue() is invoked.
> However,

Thanks for the pointer.  It would be great if you can describe / link
the actual case the patch is trying to solve.

> there is still a tiny race window left by that patch - new
> requests can get queued after the SCSI request function has been invoked
> by scsi_free_queue() and before blk_cleanup_queue() gets invoked. Hence
> the proposal to change the block layer to make sure that all queued
> requests get processed eventually.

I don't think it's a good idea to push requests out to stopped queue.
Wouldn't aborting all pending requests be better?

Thanks.

-- 
tejun

  parent reply	other threads:[~2012-03-19 17:04 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-03-18 13:18 [PATCH] block: Make blk_drain_queue() work for stopped queues Bart Van Assche
2012-03-18 15:57 ` Tejun Heo
2012-03-18 19:47   ` Bart Van Assche
2012-03-19  7:26     ` Stanislaw Gruszka
2012-03-19 17:03       ` Bart Van Assche
     [not found]         ` <4F6766F0.1070805-HInyCGIudOg@public.gmane.org>
2012-03-20 14:21           ` Stanislaw Gruszka
2012-03-20 14:31             ` Alan Stern
2012-03-19 17:04     ` Tejun Heo [this message]
2012-03-19 17:22       ` Bart Van Assche
2012-03-20 20:04       ` Bart Van Assche
2012-03-20 20:06       ` Bart Van Assche
2012-03-20 21:01         ` Dan Williams
2012-03-21  3:37           ` Dan Williams
2012-03-21 18:35             ` Dan Williams
2012-03-24 18:49             ` Bart Van Assche

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