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From: Arnd Bergmann <arnd@arndb.de>
To: Bart Van Assche <bvanassche@acm.org>
Cc: Josh Triplett <josh@joshtriplett.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	linux-kernel <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] bug: Fix CONFIG_BUG=n BUG_ON()
Date: Thu, 19 Jun 2014 19:00:14 +0200	[thread overview]
Message-ID: <5061693.b4BPIj9quA@wuerfel> (raw)
In-Reply-To: <53A2E573.6080407@acm.org>

On Thursday 19 June 2014 15:28:19 Bart Van Assche wrote:
> Patch "bug: Make BUG() always stop the machine" changed the
> behavior of BUG() with CONFIG_BUG=n from a no-op into an infinite
> loop. Modify the definition of BUG_ON() accordingly such that the
> behavior of BUG_ON(1) is identical to that of BUG().
> 
> Signed-off-by: Bart Van Assche <bvanassche@acm.org>
> Cc: Arnd Bergmann <arnd@arndb.de>
> Cc: Josh Triplett <josh@joshtriplett.org>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> ---
>  include/asm-generic/bug.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/include/asm-generic/bug.h b/include/asm-generic/bug.h
> index 630dd23..f3241cd 100644
> --- a/include/asm-generic/bug.h
> +++ b/include/asm-generic/bug.h
> @@ -142,7 +142,7 @@ extern void warn_slowpath_null(const char *file, const int line);
>  #endif
>  
>  #ifndef HAVE_ARCH_BUG_ON
> -#define BUG_ON(condition) do { if (condition) ; } while (0)
> +#define BUG_ON(condition) do { } while (unlikely(condition))
>  #endif
>  
>  #ifndef HAVE_ARCH_WARN_ON
> 

How about making it 

	do { if (condition) BUG(); } while (0)

That way it can be optimized for architectures that have their own
BUG but not BUG_ON.

	Arnd

  parent reply	other threads:[~2014-06-19 17:00 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-06-19 13:28 [PATCH] bug: Fix CONFIG_BUG=n BUG_ON() Bart Van Assche
2014-06-19 15:22 ` Josh Triplett
2014-06-19 17:00 ` Arnd Bergmann [this message]
2014-06-19 17:21   ` josh
2014-06-19 17:51     ` Bart Van Assche
2014-06-19 18:12       ` josh

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