linux-kernel - Re: [PATCH v2 1/2] Replace if statement with WARN_ON_ONCE() in cmci

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <50867FCD.9010907@cn.fujitsu.com>
Date:	Tue, 23 Oct 2012 19:30:21 +0800
From:	Tang Chen <tangchen@...fujitsu.com>
To:	Borislav Petkov <bp@...en8.de>, tony.luck@...el.com,
	tglx@...utronix.de, mingo@...hat.com, hpa@...or.com,
	miaox@...fujitsu.com, laijs@...fujitsu.com, wency@...fujitsu.com,
	x86@...nel.org, linux-edac@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 1/2] Replace if statement with WARN_ON_ONCE() in cmci_rediscover().

On 10/23/2012 05:52 PM, Borislav Petkov wrote:
> On Tue, Oct 23, 2012 at 10:55:13AM +0800, Tang Chen wrote:
>> So, how about warn once, and continue:
>> 	if (cpu == dying) {
>> 		WARN_ON_ONCE(cpu == dying);
>> 		continue;
>> 	}
>>
>> or, use BUG_ON() instead ?
>
> Let me ask you again, but I want you to think real hard this time:
>
> "Why do we need to warn? What good would that bring us?"

Hi,

First of all, I do think I was answering your question. As I said
before, if an online cpu == dying here, there must be something wrong.
Am I right here ?

If so, I think the "good" is obvious. If we don't output anything when
an online cpu == dying, nobody will know this happens. The kernel is in
wrong state, but nobody knows that, I don't see any good.

Actually, I used BUG_ON() in my v1 patch. So I dropped the if statement.
But Tejun asked me to use WARN_ON_ONCE(). And I forgot to add the if
statement.
Please refer to https://lkml.org/lkml/2012/10/16/528

And again, the "good" is inform user the kernel is in wrong state.

Thanks. :)

>

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/