linux-kernel - Re: [PATCH 1/2] proc/insterrupts: make it cpu hotplug safe

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Message-ID: <4E2FA002.2020302@jp.fujitsu.com>
Date:	Wed, 27 Jul 2011 14:20:02 +0900
From:	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
To:	yong.zhang0@...il.com
CC:	linux-s390@...r.kernel.org, linux-kernel@...r.kernel.org,
	akpm@...ux-foundation.org, kobayashi.kk@...s.nec.co.jp,
	heiko.carstens@...ibm.com
Subject: Re: [PATCH 1/2] proc/insterrupts: make it cpu hotplug safe

(2011/07/27 13:56), Yong Zhang wrote:
> KOSAKI Motonhiro noticed that the reader of /proc/interrupts
> could be preempted by cpu hotplug, thus the reader can get
> broken result due to show_interrupts() iterate every online
> cpu without any protection.
> 
> Signed-off-by: Yong Zhang <yong.zhang0@...il.com>
> Cc: Andrew Morton <akpm@...ux-foundation.org>
> Cc: Keika Kobayashi <kobayashi.kk@...s.nec.co.jp>
> Cc: KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
> Cc: Heiko Carstens <heiko.carstens@...ibm.com>

Looks good. but I have a question. On last thread, kobayashi-san
suggested to use for_each_possible_cpu() and you wrote "+1".

>> At that time, I suggested to change
>> from for_each_online_cpu() to for_each_possible_cpu(),
>> in /proc/interrupts.
>+1
>Thus we could also avoid the issue pointed by KOSAKI Motonhiro.

Why do you decide to use another way?


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