Date: Mon, 21 Aug 2006 10:02:57 +0530
From: Dipankar Sarma <dipankar@in.ibm.com>
To: Tejun Heo <htejun@gmail.com>
Cc: viro@zeniv.linux.org.uk, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] file: kill unnecessary timer in fdtable_defer
Message-ID: <20060821043257.GD5433@in.ibm.com>
Reply-To: dipankar@in.ibm.com
References: <20060820131542.GN6371@htj.dyndns.org>
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On Sun, Aug 20, 2006 at 10:15:42PM +0900, Tejun Heo wrote:
> free_fdtable_rc() schedules timer to reschedule fddef->wq if
> schedule_work() on it returns 0.  However, schedule_work() guarantees
> that the target work is executed at least once after the scheduling
> regardless of its return value.  0 return simply means that the work
> was already pending and thus no further action was required.

Hmm.. Is this really true ? IIRC, schedule_work() checks pending
work based on bit ops on work->pending and clear_bit() is not
a memory barrier. So, if I see work->pending = 1 in free_fdtable_work(), how
do I know that the work function is already executing and
missed the new work that I had queued ?


Thanks
Dipankar
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