linux-kernel - Re: [PATCH 2.6.32-rc6] workqueue: fix race condition in schedule_on_each

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Message-ID: <4AFE7200.5040601@kernel.org>
Date:	Sat, 14 Nov 2009 18:01:52 +0900
From:	Tejun Heo <tj@...nel.org>
To:	Oleg Nesterov <oleg@...hat.com>
CC:	Ingo Molnar <mingo@...hat.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	lkml <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2.6.32-rc6] workqueue: fix race condition in	schedule_on_each_cpu()

Hello, Oleg.

11/14/2009 12:38 AM, Oleg Nesterov wrote:
> A very minor nit, schedule_on_each_cpu() still checks "orig" twice,
> perhaps it makes sense to do
> 
> 	for_each_online_cpu(cpu) {
> 		struct work_struct *work = per_cpu_ptr(works, cpu);
> 
> 		INIT_WORK(work, func);
> 
> 		if (likely(cpu != orig))
> 			schedule_work_on(cpu, work);
> 		else
> 			func(work);
> 	}

The intention was to schedule works on all other cpus first and then
execute it on local cpu so that if it takes some time, it doesn't have
to go through the latency twice.

Thanks.

-- 
tejun
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