linux-kernel - Re: [V5 PATCH 3/4] kexec: Fix race between panic() and crash

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Message-ID: <20151202154023.GH3783@pd.tnic>
Date:	Wed, 2 Dec 2015 16:40:23 +0100
From:	Borislav Petkov <bp@...en8.de>
To:	河合英宏 / KAWAI，HIDEHIRO 
	<hidehiro.kawai.ez@...achi.com>
Cc:	Jonathan Corbet <corbet@....net>,
	Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...nel.org>,
	"Eric W. Biederman" <ebiederm@...ssion.com>,
	"H. Peter Anvin" <hpa@...or.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Vivek Goyal <vgoyal@...hat.com>, Baoquan He <bhe@...hat.com>,
	"linux-doc@...r.kernel.org" <linux-doc@...r.kernel.org>,
	"x86@...nel.org" <x86@...nel.org>,
	"kexec@...ts.infradead.org" <kexec@...ts.infradead.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Michal Hocko <mhocko@...nel.org>,
	平松雅巳 / HIRAMATU，MASAMI 
	<masami.hiramatsu.pt@...achi.com>
Subject: Re: [V5 PATCH 3/4] kexec: Fix race between panic() and crash_kexec()
 called directly

On Wed, Dec 02, 2015 at 11:57:38AM +0000, 河合英宏 / KAWAI，HIDEHIRO wrote:
> We can do so, but I think resetting panic_cpu always would be
> simpler and safer.

Well, I think executing code needlessly *especially* at panic time is
not all that rosy either.

Besides something like this:

	static bool kexec_failed;

	...

        if (crash_kexec_post_notifiers && !kexec_failed)
		kexec_failed = __crash_kexec(NULL);

is as simple as it gets.

-- 
Regards/Gruss,
    Boris.

ECO tip #101: Trim your mails when you reply.
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