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

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Message-ID: <CAM2zO=AiGqbyna8NeC8PZxGBJzHokLKyixE6wv6nac3-OjzcWQ@mail.gmail.com>
Date:	Wed, 27 Jul 2011 13:47:15 +0800
From:	Yong Zhang <yong.zhang0@...il.com>
To:	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.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

2011/7/27 KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>:
> (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".

Yeah, for_each_possible_cpu() will make code more cleaner.
so I give it my support.

>
>>> 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?

But, as kobayashi-san has also said:
In conclusion, we decided to remain /proc/interrupts.
because it had been the way for a long time.

So I don't want to raise an argument again :)

Thanks,
Yong


-- 
Only stand for myself
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