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From: Arnd Bergmann <arnd@arndb.de>
To: Josh Triplett <josh@joshtriplett.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 5/5] bug: Make BUG() call unreachable()
Date: Wed, 26 Feb 2014 14:29:06 +0100	[thread overview]
Message-ID: <201402261429.06553.arnd@arndb.de> (raw)
In-Reply-To: <d97712e037ea4c90e9cb30c56229383d257831de.1393385236.git.josh@joshtriplett.org>

On Wednesday 26 February 2014, Josh Triplett wrote:
> @@ -134,7 +134,7 @@ extern void warn_slowpath_null(const char *file, const int line);
>  
>  #else /* !CONFIG_BUG */
>  #ifndef HAVE_ARCH_BUG
> -#define BUG() do {} while (0)
> +#define BUG() do { unreachable(); } while (0)
>  #endif

I disagree with this one. As Alan said, we really want to use an
arch specific BUG() even in the !CONFIG_BUG case.

For the cases where this is not yet possible, I'd suggest using

#define BUG() do { } while (1)


For older gcc versions, this is actually the same as unreachable(), but
it is not the same as __builtin_unreachable, because it causes undefined
behavior.

	Arnd

  reply	other threads:[~2014-02-26 13:29 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-02-26  3:48 [PATCH v2 1/5] bug: When !CONFIG_BUG, simplify WARN_ON_ONCE and family Josh Triplett
2014-02-26  3:48 ` [PATCH v2 2/5] include/asm-generic/bug.h: Style fix: s/while(0)/while (0)/ Josh Triplett
2014-02-26 13:25   ` Arnd Bergmann
2014-02-26  3:49 ` [PATCH v2 3/5] bug: When !CONFIG_BUG, make WARN call no_printk to check format and args Josh Triplett
2014-02-26 13:25   ` Arnd Bergmann
2014-02-26  3:49 ` [PATCH v2 4/5] bug: Use a common definition of BUG_ON regardless of CONFIG_BUG Josh Triplett
2014-02-26 13:26   ` Arnd Bergmann
2014-02-26  3:49 ` [PATCH v2 5/5] bug: Make BUG() call unreachable() Josh Triplett
2014-02-26 13:29   ` Arnd Bergmann [this message]
2014-02-26 14:58     ` Josh Triplett
2014-02-27 19:19       ` Arnd Bergmann
2014-02-28  0:16         ` Josh Triplett
2014-02-28  8:55           ` Arnd Bergmann
2014-03-10  1:00             ` [PATCH v3 1/5] bug: When !CONFIG_BUG, simplify WARN_ON_ONCE and family Josh Triplett
2014-03-10  1:01               ` [PATCH v3 2/5] include/asm-generic/bug.h: Style fix: s/while(0)/while (0)/ Josh Triplett
2014-03-10  1:02               ` [PATCH v3 3/5] bug: When !CONFIG_BUG, make WARN call no_printk to check format and args Josh Triplett
2014-03-10  1:02               ` [PATCH v3 4/5] bug: Make BUG() always stop the machine Josh Triplett
2014-03-10  1:03               ` [PATCH v3 5/5] x86: Always define BUG() and HAVE_ARCH_BUG, even with !CONFIG_BUG Josh Triplett
2014-03-11 16:40               ` [PATCH v3 1/5] bug: When !CONFIG_BUG, simplify WARN_ON_ONCE and family Arnd Bergmann
2014-03-11 17:49                 ` Josh Triplett
2014-02-26 13:24 ` [PATCH v2 " Arnd Bergmann

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