Date: Sat, 22 Feb 2014 09:38:59 -0500
From: Tejun Heo <tj@kernel.org>
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
Subject: Re: [PATCH 4/9] firewire: don't use PREPARE_DELAYED_WORK
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 <5307849A.9050209@hurleysoftware.com>
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Hey,

On Fri, Feb 21, 2014 at 06:46:24PM -0500, Peter Hurley wrote:
> It's a long story but the short version is that
> Documentation/memory-barriers.txt recently was overhauled to reflect
> what cpus actually do and what the different archs actually
> deliver.
> 
> Turns out that unlock + lock is not guaranteed by all archs to be
> a full barrier. Thus the smb_mb__after_unlock_lock().
> 
> This is now all spelled out in memory-barriers.txt under the
> sub-heading "IMPLICIT KERNEL MEMORY BARRIERS".

So, that one is for unlock/lock sequence, not smp_mb__after_unlock().
Urgh... kinda dislike adding smp_rmb() there as it's one of the
barriers which translate to something weighty on most, if not all,
archs.

Thanks.

-- 
tejun
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