linux-kernel - RE: Re: [V4 PATCH 3/4] kexec: Fix race between panic() and crash

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Message-ID: <04EAB7311EE43145B2D3536183D1A84454994A2D@GSjpTKYDCembx31.service.hitachi.net>
Date:	Mon, 28 Sep 2015 04:46:52 +0000
From:	河合英宏 / KAWAI，HIDEHIRO 
	<hidehiro.kawai.ez@...achi.com>
To:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
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>,
	"linux-doc@...r.kernel.org" <linux-doc@...r.kernel.org>,
	"x86@...nel.org" <x86@...nel.org>,
	"kexec@...ts.infradead.org" <kexec@...ts.infradead.org>,
	Michal Hocko <mhocko@...nel.org>,
	平松雅巳 / HIRAMATU，MASAMI 
	<masami.hiramatsu.pt@...achi.com>,
	"kbuild-all@...org" <kbuild-all@...org>
Subject: RE: Re: [V4 PATCH 3/4] kexec: Fix race between panic() and
 crash_kexec() called directly

> Hi Hidehiro,
> 
> [auto build test results on v4.3-rc2 -- if it's inappropriate base, please ignore]
> 
> config: x86_64-allnoconfig (attached as .config)
> reproduce:
>   git checkout 0077681103150af584e5e592c0238fd010654c26
>   # save the attached .config to linux build tree
>   make ARCH=x86_64
> 
> All error/warnings (new ones prefixed by >>):
> 
>    kernel/panic.c: In function 'panic':
> >> kernel/panic.c:140:3: error: implicit declaration of function '__crash_kexec' [-Werror=implicit-function-declaration]
>       __crash_kexec(NULL);
>       ^

Sorry, I missed to take into account the case of !CONFIG_KEXEC_CORE.

 #else /* !CONFIG_KEXEC_CORE */
 struct pt_regs;
 struct task_struct;
+static inline void __crash_kexec(struct pt_regs *regs) { }
 static inline void crash_kexec(struct pt_regs *regs) { }
 static inline int kexec_should_crash(struct task_struct *p) { return 0; }

I'll resend the revised version later.

>    cc1: some warnings being treated as errors
> 
> vim +/__crash_kexec +140 kernel/panic.c
> 
>    134		 * If we have crashed and we have a crash kernel loaded let it handle
>    135		 * everything else.
>    136		 * If we want to run this after calling panic_notifiers, pass
>    137		 * the "crash_kexec_post_notifiers" option to the kernel.
>    138		 */
>    139		if (!crash_kexec_post_notifiers)
>  > 140			__crash_kexec(NULL);
>    141
>    142		/*
>    143		 * Note smp_send_stop is the usual smp shutdown function, which
> 
> ---
> 0-DAY kernel test infrastructure                Open Source Technology Center
> https://lists.01.org/pipermail/kbuild-all                   Intel Corporation


Hidehiro Kawai
Hitachi, Ltd. Research & Development Group