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Date: Fri, 13 Jun 2008 00:24:58 +0200
From: Jarek Poplawski <jarkao2@gmail.com>
To: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Andrew Morton <akpm@linux-foundation.org>, Jarek Poplawski <jarkao2@o2.pl>,
       Max Krasnyansky <maxk@qualcomm.com>,
       Peter Zijlstra <peterz@infradead.org>, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] workqueues: insert_work: use "list_head *" instead of
	"int tail"
Message-ID: <20080612222458.GC2472@ami.dom.local>
References: <20080612165120.GA12177@tv-sign.ru> <20080612165550.GA12183@tv-sign.ru>
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On Thu, Jun 12, 2008 at 08:55:50PM +0400, Oleg Nesterov wrote:
> On 06/12, Oleg Nesterov wrote:
> >
> > insert_work() inserts the new work_struct before or after cwq->worklist,
> > depending on the "int tail" parameter. Change it to accept "list_head *"
> > instead, this shrinks .text a bit and allows us to insert the barrier
> > after specific work_struct.
> 
> This allows us to implement
> 
> 	int flush_work(struct work_struct *work)
> 	{
...
> 	}
> 
> suggested by Peter. It only waits for selected work_struct.
> 
> I doubt it will have a lot of users though. In most cases we need
> cancel_work_sync() and nothing more.

I guess it could've had enough users if it were done a bit sooner...

I didn't check this implementation yet, but if it's "rtnl_lock in
other works" safe then it could've been used in David Miller's fresh
patch replacing last uses of flush_scheduled_work() in net drivers'
->stop() etc (thread: "Re: 2.6.25rc7 lockdep trace") - there would
be far less doubts about possible change of functionality.

Anyway, this idea looks right to me.

Thanks,
Jarek P.
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