Re: [V5 PATCH 3/4] kexec: Fix race between panic() and crash_kexec() called directly

From: Borislav Petkov <bp@alien8.de>
To: "河合英宏 / KAWAI，HIDEHIRO" <hidehiro.kawai.ez@hitachi.com>
Cc: "x86@kernel.org" <x86@kernel.org>, "Baoquan He" <bhe@redhat.com>,
	"Jonathan Corbet" <corbet@lwn.net>,
	"Peter Zijlstra" <peterz@infradead.org>,
	"linux-doc@vger.kernel.org" <linux-doc@vger.kernel.org>,
	"kexec@lists.infradead.org" <kexec@lists.infradead.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"Michal Hocko" <mhocko@kernel.org>,
	"Thomas Gleixner" <tglx@linutronix.de>,
	"Eric W. Biederman" <ebiederm@xmission.com>,
	"H. Peter Anvin" <hpa@zytor.com>,
	"平松雅巳 / HIRAMATU，MASAMI" <masami.hiramatsu.pt@hitachi.com>,
	"Andrew Morton" <akpm@linux-foundation.org>,
	"Ingo Molnar" <mingo@kernel.org>,
	"Vivek Goyal" <vgoyal@redhat.com>
Subject: Re: [V5 PATCH 3/4] kexec: Fix race between panic() and crash_kexec() called directly
Date: Wed, 2 Dec 2015 16:40:23 +0100	[thread overview]
Message-ID: <20151202154023.GH3783@pd.tnic> (raw)
In-Reply-To: <04EAB7311EE43145B2D3536183D1A84454A3B032@GSjpTKYDCembx31.service.hitachi.net>

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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