From: Martin Schwidefsky <schwidefsky@de•ibm.com>
To: Tejun Heo <tj@kernel•org>
Cc: Sachin Sant <sachinp@in•ibm.com>,
linux-s390@vger•kernel.org,
linux-kernel <linux-kernel@vger•kernel.org>,
"linux-next@vger•kernel.org" <linux-next@vger•kernel.org>
Subject: Re: [PATCH wq#for-next] workqueue: fix how cpu number is stored in work->data
Date: Thu, 22 Jul 2010 17:10:28 +0200 [thread overview]
Message-ID: <20100722171028.2aa0b8f2@mschwide.boeblingen.de.ibm.com> (raw)
In-Reply-To: <4C4838B8.1080400@kernel.org>
On Thu, 22 Jul 2010 14:25:28 +0200
Tejun Heo <tj@kernel•org> wrote:
> Once a work starts execution, its data contains the cpu number it was
> on instead of pointing to cwq. This is added by commit 7a22ad75
> (workqueue: carry cpu number in work data once execution starts) to
> reliably determine the work was last on even if the workqueue itself
> was destroyed inbetween.
>
> Whether data points to a cwq or contains a cpu number was
> distinguished by comparing the value against PAGE_OFFSET. The
> assumption was that a cpu number should be below PAGE_OFFSET while a
> pointer to cwq should be above it. However, on architectures which
> use separate address spaces for user and kernel spaces, this doesn't
> hold as PAGE_OFFSET is zero.
>
> Fix it by using an explicit flag, WORK_STRUCT_CWQ, to mark what the
> data field contains. If the flag is set, it's pointing to a cwq;
> otherwise, it contains a cpu number.
>
> Reported on s390 and microblaze during linux-next testing.
>
> Signed-off-by: Tejun Heo <tj@kernel•org>
> Reported-by: Sachin Sant <sachinp@in•ibm.com>
> Reported-by: Michal Simek <michal.simek@petalogix•com>
> Reported-by: Martin Schwidefsky <schwidefsky@de•ibm.com>
> ---
> Yeah, that was a stupid assumption by me. Can you guys please test
> whether this fixes the problem?
Compiles and boots for s390. Thanks.
--
blue skies,
Martin.
"Reality continues to ruin my life." - Calvin.
next prev parent reply other threads:[~2010-07-22 15:10 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-07-21 10:40 [-next July 21] s390 build failure : kernel/workqueue.o Sachin Sant
2010-07-21 15:57 ` Tejun Heo
2010-07-22 5:49 ` Sachin Sant
2010-07-22 9:25 ` Martin Schwidefsky
2010-07-22 12:25 ` [PATCH wq#for-next] workqueue: fix how cpu number is stored in work->data Tejun Heo
2010-07-22 15:10 ` Martin Schwidefsky [this message]
2010-07-22 20:41 ` Tejun Heo
2010-07-22 20:13 ` Michal Simek
2010-07-22 7:19 ` [-next July 21] s390 build failure : kernel/workqueue.o Michal Simek
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