From: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
To: yong.zhang0@gmail.com
Cc: linux-kernel@vger.kernel.org, akpm@linux-foundation.org,
kobayashi.kk@ncos.nec.co.jp
Subject: Re: [PATCH] proc/softirqs: only show state for online cpus
Date: Tue, 26 Jul 2011 16:52:38 +0900 [thread overview]
Message-ID: <4E2E7246.6050204@jp.fujitsu.com> (raw)
In-Reply-To: <CAM2zO=CxriXK4bqGbwhfkfdgSpGwe1mAJE=6cYpDAf0Hxji0sQ@mail.gmail.com>
>> Offtopic, /proc/interrupt should be protected by get_online_cpus().
>> Otherwise the header (i.e. cpu number) and the actual statistics fields
>> can be mismatched likes following. Am I missing something?
>
> I think you are right. The reader could be preempted by cpu hotplug.
>
> After searching the whole tree, only s390 take cpu_hotplug.lock,
> but its usage is not currect:
>
> arch/s390/kernel/irq.c:
> int show_interrupts(struct seq_file *p, void *v)
> {
> get_online_cpus();
> .........
> put_online_cpus();
> }
>
> Because the reader will call show_interrupts nr_irqs times.
> So get_online_cpus()/put_online_cpus() should be put upper,
> maybe interrupts_open(). How do you think about it?
I agree with you.
next prev parent reply other threads:[~2011-07-26 7:52 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-07-25 13:10 [PATCH] proc/softirqs: only show state for online cpus Yong Zhang
2011-07-26 5:28 ` KOSAKI Motohiro
2011-07-26 6:14 ` Yong Zhang
2011-07-26 6:38 ` KOSAKI Motohiro
2011-07-26 7:29 ` Yong Zhang
2011-07-26 7:46 ` Keika Kobayashi
2011-07-26 7:56 ` Yong Zhang
2011-07-26 7:52 ` KOSAKI Motohiro [this message]
2011-07-26 16:34 ` Heiko Carstens
2011-07-27 2:41 ` Yong Zhang
2011-07-27 4:56 ` [PATCH 1/2] proc/insterrupts: make it cpu hotplug safe Yong Zhang
2011-07-27 4:56 ` [PATCH 2/2] [S390] irq: fix show_interrupts() vs cpu hotplug Yong Zhang
2011-07-27 6:06 ` Heiko Carstens
2011-07-27 5:20 ` [PATCH 1/2] proc/insterrupts: make it cpu hotplug safe KOSAKI Motohiro
2011-07-27 5:47 ` Yong Zhang
2011-07-27 5:55 ` KOSAKI Motohiro
2011-07-27 6:05 ` Heiko Carstens
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