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From: Al Viro <viro@ftp.linux.org.uk>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org
Subject: [PATCH][RFC] getting rid of stupid loop in BUG()
Date: Tue, 24 Jul 2007 16:39:16 +0100	[thread overview]
Message-ID: <20070724153916.GS21668@ftp.linux.org.uk> (raw)

	AFAICS, the patch below should do it for i386; instead of
using a dummy loop to tell gcc that this sucker never returns,
we do
static void __always_inline __noreturn __BUG(const char *file, int line);
containing the actual asm we want to insert and define BUG() as
__BUG(__FILE__, __LINE__).  It looks safe, but I don't claim enough
experience with gcc __asm__ potential nastiness, so...

Comments, objections?

diff --git a/include/asm-i386/bug.h b/include/asm-i386/bug.h
index b0fd78c..294bc55 100644
--- a/include/asm-i386/bug.h
+++ b/include/asm-i386/bug.h
@@ -7,31 +7,27 @@
  * The offending file and line are encoded encoded in the __bug_table section.
  */
 
-#ifdef CONFIG_BUG
 #define HAVE_ARCH_BUG
 
-#ifdef CONFIG_DEBUG_BUGVERBOSE
-#define BUG()								\
-	do {								\
-		asm volatile("1:\tud2\n"				\
-			     ".pushsection __bug_table,\"a\"\n"		\
-			     "2:\t.long 1b, %c0\n"			\
-			     "\t.word %c1, 0\n"				\
-			     "\t.org 2b+%c2\n"				\
-			     ".popsection"				\
-			     : : "i" (__FILE__), "i" (__LINE__),	\
-			     "i" (sizeof(struct bug_entry)));		\
-		for(;;) ;						\
-	} while(0)
+#define BUG() __BUG(__FILE__, __LINE__)
+
+#include <asm-generic/bug.h>
 
+#ifdef CONFIG_BUG
+static void __always_inline __noreturn __BUG(const char *file, int line)
+{
+#ifdef CONFIG_DEBUG_BUGVERBOSE
+	asm volatile("1:\tud2\n"
+		     ".pushsection __bug_table,\"a\"\n"
+		     "2:\t.long 1b, %c0\n"
+		     "\t.word %c1, 0\n"
+		     "\t.org 2b+%c2\n"
+		     ".popsection"
+		     : : "i" (file), "i" (line),
+		     "i" (sizeof(struct bug_entry)));
 #else
-#define BUG()								\
-	do {								\
-		asm volatile("ud2");					\
-		for(;;) ;						\
-	} while(0)
+	asm volatile("ud2");
 #endif
+}
 #endif
-
-#include <asm-generic/bug.h>
 #endif

             reply	other threads:[~2007-07-24 15:39 UTC|newest]

Thread overview: 36+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-07-24 15:39 Al Viro [this message]
2007-07-24 16:56 ` [PATCH][RFC] getting rid of stupid loop in BUG() Jeremy Fitzhardinge
2007-07-24 17:03   ` H. Peter Anvin
2007-07-24 17:14   ` Al Viro
2007-07-24 17:28     ` H. Peter Anvin
2007-07-24 18:58       ` Jeremy Fitzhardinge
2007-07-24 19:01         ` H. Peter Anvin
2007-07-24 19:13     ` Jeremy Fitzhardinge
2007-07-24 20:04       ` Al Viro
2007-07-24 21:14         ` Jeremy Fitzhardinge
2007-07-25  2:31 ` Trent Piepho
2007-07-25  2:50   ` Keith Owens
2007-07-25  5:09     ` H. Peter Anvin
2007-07-25  6:24       ` Jeremy Fitzhardinge
2007-07-25  6:29         ` David Miller
2007-07-25  6:50           ` Heiko Carstens
2007-07-25 16:56           ` Linus Torvalds
2007-07-25 17:00             ` Jeremy Fitzhardinge
2007-07-25 17:03               ` H. Peter Anvin
2007-07-25 17:19               ` Linus Torvalds
2007-07-25 17:25                 ` Al Viro
2007-07-25 17:36                   ` Jeremy Fitzhardinge
2007-07-25 19:35                     ` David Miller
2007-07-25 20:26                       ` H. Peter Anvin
2007-07-25 19:28               ` David Miller
2007-07-25 17:19             ` Al Viro
2007-07-25 17:22               ` H. Peter Anvin
2007-07-25 17:26                 ` Al Viro
2007-07-25 17:35                   ` David Howells
2007-07-25 17:41               ` Jeremy Fitzhardinge
2007-07-25 20:29                 ` Chuck Ebbert
2007-07-25 20:37                   ` H. Peter Anvin
2007-07-25 22:01                     ` David Miller
2007-07-25 18:24               ` Linus Torvalds
2007-07-25 17:36             ` Al Viro
2007-07-25 17:44               ` Jeremy Fitzhardinge

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