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From: Tejun Heo <tj@kernel.org>
To: laijs@cn.fujitsu.com
Cc: linux-kernel@vger.kernel.org, Peter Hurley <peter@hurleysoftware.com>
Subject: Re: [PATCH 9/9] workqueue: remove PREPARE_[DELAYED_]WORK()
Date: Fri, 7 Mar 2014 10:27:44 -0500	[thread overview]
Message-ID: <20140307152744.GI30778@htj.dyndns.org> (raw)
In-Reply-To: <1392929071-16555-10-git-send-email-tj@kernel.org>

On Thu, Feb 20, 2014 at 03:44:31PM -0500, Tejun Heo wrote:
> Peter Hurley noticed that since a2c1c57be8d9 ("workqueue: consider
> work function when searching for busy work items"), a work item which
> gets assigned a different work function would break out of the
> non-reentrancy guarantee as workqueue would consider it a different
> work item.
> 
> This is fragile and extremely subtle.  PREPARE_[DELAYED_]WORK() have
> never been used widely and its semantics has always been somewhat
> iffy.  If the work item is known not to be on queue when
> PREPARE_WORK() is called, there's no difference from using
> INIT_WORK().  If the work item may be queued at the time of
> PREPARE_WORK(), we can't really tell whether the old or new function
> will be executed the next time.
> 
> We really don't want this level of subtlety in workqueue interface for
> such marginal use cases.  The previous patches converted all existing
> users away from PREPARE_[DELAYED_]WORK().  Let's remove them.
> 
> Signed-off-by: Tejun Heo <tj@kernel.org>
> Cc: Peter Hurley <peter@hurleysoftware.com>
> Link: http://lkml.kernel.org/g/1392493119-9277-1-git-send-email-peter@hurleysoftware.com

Applied to wq/for-3.15.

Thanks.

-- 
tejun

  reply	other threads:[~2014-03-07 15:27 UTC|newest]

Thread overview: 75+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-02-20 20:44 [PATCHSET wq/for-3.15] workqueue: remove PREPARE_[DELAYED_]WORK() Tejun Heo
2014-02-20 20:44 ` [PATCH 1/9] wireless/rt2x00: don't use PREPARE_WORK in rt2800usb.c Tejun Heo
2014-03-07 15:26   ` Tejun Heo
2014-02-20 20:44 ` [PATCH 2/9] ps3-vuart: don't use PREPARE_WORK Tejun Heo
2014-02-20 20:44   ` Tejun Heo
2014-02-21 23:19   ` Geoff Levand
2014-02-21 23:19     ` Geoff Levand
2014-02-20 20:44 ` [PATCH 3/9] floppy: don't use PREPARE_[DELAYED_]WORK Tejun Heo
2014-02-21  9:37   ` Jiri Kosina
2014-02-20 20:44 ` [PATCH 4/9] firewire: don't use PREPARE_DELAYED_WORK Tejun Heo
2014-02-20 20:44   ` 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  2:07         ` Peter Hurley
2014-02-21  2:13         ` Tejun Heo
2014-02-21  5:13           ` Peter Hurley
2014-02-21 10:03             ` Tejun Heo
2014-02-21 12:51               ` Peter Hurley
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 14:38                               ` 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 18:48                             ` Peter Hurley
2014-02-22 18:52                             ` James Bottomley
2014-02-22 19:03                               ` Peter Hurley
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 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 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
2014-02-21 20:45     ` Stefan Richter
2014-03-05 21:34     ` Stefan Richter
2014-03-07 15:18       ` Tejun Heo
2014-03-07 15:26   ` [PATCH UPDATED " Tejun Heo
2014-03-07 15:26     ` Tejun Heo
2014-02-20 20:44 ` [PATCH 5/9] usb: " Tejun Heo
2014-02-20 20:59   ` Greg Kroah-Hartman
2014-02-21 15:06     ` Alan Stern
2014-02-21 15:07       ` Tejun Heo
2014-02-22 14:59   ` [PATCH v2 " Tejun Heo
2014-02-22 15:14     ` Alan Stern
2014-02-22 15:20       ` Peter Hurley
2014-02-22 15:37       ` Tejun Heo
2014-02-22 23:03         ` Alan Stern
2014-02-23  4:29           ` Tejun Heo
2014-02-20 20:44 ` [PATCH 6/9] nvme: don't use PREPARE_WORK Tejun Heo
2014-02-20 20:44   ` Tejun Heo
2014-03-07 15:26   ` Tejun Heo
2014-03-07 15:26     ` Tejun Heo
2014-02-20 20:44 ` [PATCH 7/9] afs: " Tejun Heo
2014-03-07 15:27   ` Tejun Heo
2014-02-20 20:44 ` [PATCH 8/9] staging/fwserial: " Tejun Heo
2014-02-21 15:13   ` Peter Hurley
2014-02-20 20:44 ` [PATCH 9/9] workqueue: remove PREPARE_[DELAYED_]WORK() Tejun Heo
2014-03-07 15:27   ` Tejun Heo [this message]
2014-02-20 22:00 ` [PATCH 7/9] afs: don't use PREPARE_WORK David Howells
2014-02-20 22:46   ` Tejun Heo

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