[x86] BUG()/BUG_ON() macros cannot be disabled

[Alexander Lochmann]

Hi Arnd,

I recently tried to disable the BUG macros on x86-32. I disabled the
config item in 'General Setup -> Configure standard kernel features
(expert users) -> BUG() support'.
However, BUG/BUG_ON is still defined. In the !CONFIG_BUG branch in
include/asm-generic/bug.h (line 181) the code checks for the existence
of architecture-specific variants of those macros.
Since x86 defines its own version of BUG(), line 182 is *not* used.
In the following, the x86 variant of BUG() is then used to define the
BUG_ON() macro.

I propose a patch that really disables both macros if the developer
wants it.
It undefines the respective x86 variants, and defines both macros as
'empty' macros.

Regards,
Alex

-- 
Technische UniversitÃt Dortmund
Alexander Lochmann                PGP key: 0xBC3EF6FD
Otto-Hahn-Str. 16                 phone:  +49.231.7556141
D-44227 Dortmund                  fax:    +49.231.7556116
http://ess.cs.tu-dortmund.de/Staff/al
diff --git a/include/asm-generic/bug.h b/include/asm-generic/bug.h
index 20561a60db9c..1e7977582277 100644
--- a/include/asm-generic/bug.h
+++ b/include/asm-generic/bug.h
@@ -178,14 +178,17 @@ void __warn(const char *file, int line, void *caller, unsigned taint,
 })
 
 #else /* !CONFIG_BUG */
-#ifndef HAVE_ARCH_BUG
-#define BUG() do {} while (1)
+#ifdef HAVE_ARCH_BUG
+#undef BUG
 #endif
 
-#ifndef HAVE_ARCH_BUG_ON
-#define BUG_ON(condition) do { if (condition) BUG(); } while (0)
+#ifdef HAVE_ARCH_BUG_ON
+#undef BUG_ON
 #endif
 
+#define BUG_ON(condition) do { if (condition) BUG(); } while (0)
+#define BUG() do {} while (1)
+
 #ifndef HAVE_ARCH_WARN_ON
 #define WARN_ON(condition) ({						\
 	int __ret_warn_on = !!(condition);				\

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