linux-kernel - Re: [PATCH] firewire: sbp2: parallelize login/inquiry, reconnect, and shutdown

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Message-ID: <4CB467A3.4010200@kernel.org>
Date:	Tue, 12 Oct 2010 15:50:27 +0200
From:	Tejun Heo <tj@...nel.org>
To:	Stefan Richter <stefanr@...6.in-berlin.de>
CC:	linux1394-devel@...ts.sourceforge.net, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] firewire: sbp2: parallelize login/inquiry, reconnect,
 and shutdown

Hello,

On 10/11/2010 11:27 PM, Stefan Richter wrote:
>> Hmmm... from glancing the code, there doesn't seem to anything which
>> can guarantee sbp2_release_target/reconnect() are finished before
>> sbp2_cleanup() returns, so the code section might go away with code
>> still running.  It seems like the right thing to do here would be
>> using alloc_workqueue(KBUILD_MODNAME, WQ_NON_REENTRANT, 0).  Am I
>> missing something?
> 
> There are indeed situations where the last module reference was already
> put down before the work is run for the last time.  Thanks for the hint.
> 
> What is preferable, an own workqueue instance whose destroy_workqueue()
> lets sbp2_cleanup wait for unfinished work, or module ref-counting like
> below?

The best would be flushing the specific works but that isn't possible
when works are used to do the final put.  I would go for using a
separate workqueue.  With cmwq, each workqueue is much cheaper than
before anyway.

Thanks.

-- 
tejun
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