linux-kernel - Re: [PATCH v8] kernel, add panic_on

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Date:	Thu, 06 Nov 2014 17:52:05 -0500
From:	Prarit Bhargava <prarit@...hat.com>
To:	Vivek Goyal <vgoyal@...hat.com>
CC:	David Rientjes <rientjes@...gle.com>, linux-kernel@...r.kernel.org,
	Jonathan Corbet <corbet@....net>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Rusty Russell <rusty@...tcorp.com.au>,
	"H. Peter Anvin" <hpa@...or.com>, Andi Kleen <ak@...ux.intel.com>,
	Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>,
	Fabian Frederick <fabf@...net.be>,
	isimatu.yasuaki@...fujitsu.com, jbaron@...mai.com,
	linux-doc@...r.kernel.org, kexec@...ts.infradead.org,
	linux-api@...r.kernel.org
Subject: Re: [PATCH v8] kernel, add panic_on_warn



On 11/06/2014 05:07 PM, Vivek Goyal wrote:
> On Thu, Nov 06, 2014 at 01:57:36PM -0800, David Rientjes wrote:
> 
> [..]
>> You see that doing
>>
>> 	if (panic_on_warn) {
>> 		panic_on_warn = 0;
>> 		panic(...);
>> 	}
>>
>> is racy, I hope.  If two threads WARN() at the same time, then there's 
>> nothing preventing a double panic() because WARN() itself is not 
>> serialized against anything.  So both the current comment and your 
>> suggested revision comment are bogus.
> 
> panic() is serialized on panic_lock. So I guess it is fine to hit WARN()
> on multiple cpus. Do you see an issue there?

Oops -- didn't see this until just now.

Once again, Vivek beat me to the punch :) and much more succinctly than I will
ever be able to do. :)

P.

> 
> Thanks
> Vivek
> 
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