From mboxrd@z Thu Jan  1 00:00:00 1970
Return-path: <kexec-bounces+dwmw2=infradead.org@lists.infradead.org>
Received: from mx1.redhat.com ([209.132.183.28])
 by bombadil.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux))
 id 1XmVuz-0003WG-UN
 for kexec@lists.infradead.org; Thu, 06 Nov 2014 22:52:42 +0000
Message-ID: <545BFB95.5030706@redhat.com>
Date: Thu, 06 Nov 2014 17:52:05 -0500
From: Prarit Bhargava <prarit@redhat.com>
MIME-Version: 1.0
Subject: Re: [PATCH v8] kernel, add panic_on_warn
References: <1415187736-16242-1-git-send-email-prarit@redhat.com>
 <alpine.DEB.2.10.1411051357050.31575@chino.kir.corp.google.com>
 <545B733C.6080903@redhat.com>
 <alpine.DEB.2.10.1411061352440.1526@chino.kir.corp.google.com>
 <20141106220731.GA13590@redhat.com>
In-Reply-To: <20141106220731.GA13590@redhat.com>
List-Id: <kexec.lists.infradead.org>
List-Unsubscribe: <http://lists.infradead.org/mailman/options/kexec>,
 <mailto:kexec-request@lists.infradead.org?subject=unsubscribe>
List-Archive: <http://lists.infradead.org/pipermail/kexec/>
List-Post: <mailto:kexec@lists.infradead.org>
List-Help: <mailto:kexec-request@lists.infradead.org?subject=help>
List-Subscribe: <http://lists.infradead.org/mailman/listinfo/kexec>,
 <mailto:kexec-request@lists.infradead.org?subject=subscribe>
Content-Type: text/plain; charset="us-ascii"
Content-Transfer-Encoding: 7bit
Sender: "kexec" <kexec-bounces@lists.infradead.org>
Errors-To: kexec-bounces+dwmw2=infradead.org@lists.infradead.org
To: Vivek Goyal <vgoyal@redhat.com>
Cc: Andi Kleen <ak@linux.intel.com>, Jonathan Corbet <corbet@lwn.net>, jbaron@akamai.com, kexec@lists.infradead.org, Rusty Russell <rusty@rustcorp.com.au>, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, Fabian Frederick <fabf@skynet.be>, isimatu.yasuaki@jp.fujitsu.com, "H. Peter Anvin" <hpa@zytor.com>, Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>, David Rientjes <rientjes@google.com>, Andrew Morton <akpm@linux-foundation.org>, linux-api@vger.kernel.org



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
> 

_______________________________________________
kexec mailing list
kexec@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/kexec