linux-kernel - Re: [PATCH v2 1/2] Replace if statement with WARN_ON_ONCE() in cmci

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Message-ID: <20121022101442.GB8352@liondog.tnic>
Date:	Mon, 22 Oct 2012 12:14:42 +0200
From:	Borislav Petkov <bp@...en8.de>
To:	Tang Chen <tangchen@...fujitsu.com>
Cc:	Borislav Petkov <bp@...64.org>, tony.luck@...el.com,
	tglx@...utronix.de, mingo@...hat.com, hpa@...or.com,
	miaox@...fujitsu.com, laijs@...fujitsu.com, wency@...fujitsu.com,
	x86@...nel.org, linux-edac@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 1/2] Replace if statement with WARN_ON_ONCE() in
 cmci_rediscover().

On Mon, Oct 22, 2012 at 10:10:24AM +0800, Tang Chen wrote:
> I don't why before we just jumped over it. But I think if we have an
> online cpu == dying here, it must be wrong. So I think we should warn
> it, not just jump over it.

Why do we need to warn? What good would that bring us?

AFAICT, the check in cmci_rediscover is there to make sure we absolutely
don't rediscover on the dying cpu. I think it is a safety precaution in
concurrency scenarios between cpu hotplug and mce code.

Thanks.

-- 
Regards/Gruss,
    Boris.
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