netdev - Re: [PATCH net-next-2.6] bnx2: remove cancel_work_sync() from remove

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Message-ID: <4D08C81D.8020606@kernel.org>
Date:	Wed, 15 Dec 2010 14:52:29 +0100
From:	Tejun Heo <tj@...nel.org>
To:	Michael Chan <mchan@...adcom.com>,
	"David S. Miller" <davem@...emloft.net>,
	netdev <netdev@...r.kernel.org>
CC:	lkml <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH net-next-2.6] bnx2: remove cancel_work_sync() from remove_one

On 12/14/2010 06:48 PM, Michael Chan wrote:
> 
> On Tue, 2010-12-14 at 08:09 -0800, Tejun Heo wrote:
>> Michael pointed out that bnx2_close() already cancels bp->reset_task
>> and thus it is guaranteed to be idle when bnx2_remove_one() is called.
>> Remove the unnecessary cancel_work_sync() in remove_one.
>>
>> Signed-off-by: Tejun Heo <tj@...nel.org>
>> Cc: Michael Chan <mchan@...adcom.com>
> 
> Acked-by: Michael Chan <mchan@...adcom.com>

After looking through the code, I don't think this is necessarily
correct.  ->ndo_close() doesn't guarantee that the watchdog timer has
finished running (the timer is deleted with del_timer() not
del_timer_sync()).  ie. the watchdog timer could still be running
after ->ndo_close() and may schedule reset_task.  If remove_one
doesn't flush the task, it may still be running when remove_one() is
called.

David, am I missing something?  Wouldn't it cleaner to guarantee that
->ndo_close() is called with the guarantee that the watchdog timer is
not running anymore?

-- 
tejun
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