linux-kernel - Re: Performance Question: BUG_ON vs. WARN_ON

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Date:	Mon, 14 Jul 2008 06:36:57 +0300
From:	Eduard - Gabriel Munteanu <eduard.munteanu@...ux360.ro>
To:	"Ryan Hope" <rmh3093@...il.com>
Cc:	LKML <linux-kernel@...r.kernel.org>,
	"Nick Piggin" <nickpiggin@...oo.com.au>
Subject: Re: Performance Question: BUG_ON vs. WARN_ON_ONCE

On Sun, 13 Jul 2008 19:57:37 -0400
"Ryan Hope" <rmh3093@...il.com> wrote:

> However, this causes the kernel to crash or oops under certain loads.
> Reverting this change makes the error go away. Is there any sort of
> performance difference between BUG_ON and WARN_ON_ONCE, I figure the
> change was for a reason so I am wondering what will result from this
> change. Any info would be appreciated.
> 
> -Ryan

Looks like WARN_ON_ONCE declares and uses a static int variable, so
it's not reentrant. It should be an atomic static. Still, I don't see
how this could crash the kernel or even oops, or have any other
side-effects.

Could you post the oops? Are you sure the oops you're seeing isn't just
what WARN_ON et al. regularly produce?


	Eduard
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