From mboxrd@z Thu Jan  1 00:00:00 1970
From: Tejun Heo <tj@kernel.org>
Subject: Re: [PATCH 4/9] firewire: don't use PREPARE_DELAYED_WORK
Date: Thu, 20 Feb 2014 20:59:35 -0500
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 <5306AF8E.3080006@hurleysoftware.com>
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To: Peter Hurley <peter@hurleysoftware.com>
Cc: laijs@cn.fujitsu.com, linux-kernel@vger.kernel.org, Stefan Richter <stefanr@s5r6.in-berlin.de>, linux1394-devel@lists.sourceforge.net, Chris Boot <bootc@bootc.net>, linux-scsi@vger.kernel.org, target-devel@vger.kernel.org
List-Id: linux-scsi@vger.kernel.org

Hello,

On Thu, Feb 20, 2014 at 08:44:46PM -0500, Peter Hurley wrote:
> >+static void fw_device_workfn(struct work_struct *work)
> >+{
> >+	struct fw_device *device = container_of(to_delayed_work(work),
> >+						struct fw_device, work);
> 
> I think this needs an smp_rmb() here.

The patch is equivalent transformation and the whole thing is
guaranteed to have gone through pool->lock.  No explicit rmb
necessary.

> IOW, the beginning of the work function should act like a barrier in
> the same way that queue_work_on() (et. al.) already does.

workqueue already has enough barriers; otherwise, the whole kernel
would have crumbled long time ago.

Thanks.

-- 
tejun