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
Date: Thu, 20 Feb 2014 21:13:41 -0500 [thread overview]
Message-ID: <20140221021341.GG6897@htj.dyndns.org> (raw)
In-Reply-To: <5306B4DF.4000901@hurleysoftware.com>
On Thu, Feb 20, 2014 at 09:07:27PM -0500, Peter Hurley wrote:
> On 02/20/2014 08:59 PM, Tejun Heo wrote:
> >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.
>
> The spin_unlock_irq(&pool->lock) only guarantees completion of
> memory operations _before_ the unlock; memory operations which occur
> _after_ the unlock may be speculated before the unlock.
>
> IOW, unlock is not a memory barrier for operations that occur after.
It's not just unlock. It's lock / unlock pair on the same lock from
both sides. Nothing can sip through that.
--
tejun
next prev parent reply other threads:[~2014-02-21 2:13 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <1392929071-16555-1-git-send-email-tj@kernel.org>
2014-02-20 20:44 ` [PATCH 4/9] firewire: don't use PREPARE_DELAYED_WORK Tejun Heo
2014-02-21 1:44 ` Peter Hurley
2014-02-21 1:59 ` Tejun Heo
2014-02-21 2:07 ` Peter Hurley
2014-02-21 2:13 ` Tejun Heo [this message]
2014-02-21 5:13 ` Peter Hurley
2014-02-21 10:03 ` Tejun Heo
2014-02-21 12:51 ` Peter Hurley
2014-02-21 13:06 ` Tejun Heo
2014-02-21 16:53 ` Peter Hurley
2014-02-21 16:57 ` Tejun Heo
2014-02-21 23:01 ` Peter Hurley
2014-02-21 23:18 ` Tejun Heo
2014-02-21 23:46 ` Peter Hurley
2014-02-22 14:38 ` Tejun Heo
2014-02-22 14:48 ` Peter Hurley
2014-02-22 18:43 ` James Bottomley
2014-02-22 18:48 ` Peter Hurley
2014-02-22 18:52 ` James Bottomley
2014-02-22 19:03 ` Peter Hurley
2014-02-23 1:23 ` memory-barriers.txt again (was Re: [PATCH 4/9] firewire: don't use PREPARE_DELAYED_WORK) Stefan Richter
2014-02-23 16:37 ` Paul E. McKenney
2014-02-23 20:35 ` Peter Hurley
2014-02-23 23:50 ` Paul E. McKenney
2014-02-24 0:09 ` Peter Hurley
2014-02-24 16:26 ` Paul E. McKenney
2014-02-24 0:32 ` Stefan Richter
2014-02-24 16:27 ` Paul E. McKenney
2014-02-23 20:05 ` [PATCH 4/9] firewire: don't use PREPARE_DELAYED_WORK James Bottomley
2014-02-23 22:32 ` Peter Hurley
2014-02-21 20:45 ` Stefan Richter
2014-03-07 15:26 ` [PATCH UPDATED " Tejun Heo
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