linux-kernel - Re: [v2 PATCH 1/3] panic: Change nmi

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Message-ID: <20160302131824.GH26686@dhcp22.suse.cz>
Date:	Wed, 2 Mar 2016 14:18:24 +0100
From:	Michal Hocko <mhocko@...nel.org>
To:	Hidehiro Kawai <hidehiro.kawai.ez@...achi.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Thomas Mingarelli <thomas.mingarelli@....com>,
	Wim Van Sebroeck <wim@...ana.be>,
	Corey Minyard <minyard@....org>,
	Javi Merino <javi.merino@....com>,
	linux-watchdog@...r.kernel.org,
	"Steven Rostedt (Red Hat)" <rostedt@...dmis.org>,
	Rasmus Villemoes <linux@...musvillemoes.dk>,
	linux-kernel@...r.kernel.org,
	Michal Nazarewicz <mina86@...a86.com>,
	Vitaly Kuznetsov <vkuznets@...hat.com>,
	HATAYAMA Daisuke <d.hatayama@...fujitsu.com>,
	Borislav Petkov <bp@...en8.de>,
	Gobinda Charan Maji <gobinda.cemk07@...il.com>,
	Tejun Heo <tj@...nel.org>,
	Nicolas Iooss <nicolas.iooss_linux@....org>,
	openipmi-developer@...ts.sourceforge.net,
	Borislav Petkov <bp@...e.de>,
	Thomas Gleixner <tglx@...utronix.de>,
	Guenter Roeck <linux@...ck-us.net>
Subject: Re: [v2 PATCH 1/3] panic: Change nmi_panic from macro to function

On Wed 02-03-16 19:36:26, Hidehiro Kawai wrote:
[...]
> +void nmi_panic(struct pt_regs *regs, const char *fmt, ...)

Do we really need vargs? All the current users seem to be OK with a
simple string. This makes the code slightly more complicated without any
apparent reason.

> +{
> +	static char buf[1024]; /* protected by panic_cpu */
> +	va_list args;
> +	int old_cpu, cpu;
> +
> +	cpu = raw_smp_processor_id();
> +	old_cpu = atomic_cmpxchg(&panic_cpu, PANIC_CPU_INVALID, cpu);
> +
> +	if (old_cpu == PANIC_CPU_INVALID) {
> +		va_start(args, fmt);
> +		vsnprintf(buf, sizeof(buf), fmt, args);
> +		va_end(args);
> +
> +		panic("%s", buf);
> +	} else if (old_cpu != cpu)
> +		nmi_panic_self_stop(regs);
> +}
> +EXPORT_SYMBOL(nmi_panic);
> +
>  /**
>   *	panic - halt the system
>   *	@fmt: The text string to print
> 
> 

-- 
Michal Hocko
SUSE Labs