[PATCH] Let WARN_ON/WARN_ON_ONCE return the condition

Letting WARN_ON/WARN_ON_ONCE return the condition means that you could do

if (WARN_ON(blah)) {
	handle_impossible_case
}

Rather than

if (unlikely(blah)) {
	WARN_ON(1)
	handle_impossible_case
}

I checked all the newly added WARN_ON_ONCE users and none of them test the
return status so we can still change it.

[akpm@osdl.org: warning fix]
[akpm@osdl.org: build fix]
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

include/asm-generic/bug.h

@@ -16,12 +16,15 @@
 #endif
 
 #ifndef HAVE_ARCH_WARN_ON
-#define WARN_ON(condition) do { \
-	if (unlikely((condition)!=0)) { \
-		printk("BUG: warning at %s:%d/%s()\n", __FILE__, __LINE__, __FUNCTION__); \
-		dump_stack(); \
-	} \
-} while (0)
+#define WARN_ON(condition) ({						\
+	typeof(condition) __ret_warn_on = (condition);			\
+	if (unlikely(__ret_warn_on)) {					\
+		printk("BUG: warning at %s:%d/%s()\n", __FILE__,	\
+			__LINE__, __FUNCTION__);			\
+		dump_stack();						\
+	}								\
+	unlikely(__ret_warn_on);					\
+})
 #endif
 
 #else /* !CONFIG_BUG */
@@ -34,21 +37,18 @@
 #endif
 
 #ifndef HAVE_ARCH_WARN_ON
-#define WARN_ON(condition) do { if (condition) ; } while(0)
+#define WARN_ON(condition) unlikely((condition))
 #endif
 #endif
 
-#define WARN_ON_ONCE(condition)				\
-({							\
+#define WARN_ON_ONCE(condition)	({			\
 	static int __warn_once = 1;			\
-	int __ret = 0;					\
+	typeof(condition) __ret_warn_once = (condition);\
 							\
-	if (unlikely((condition) && __warn_once)) {	\
-		__warn_once = 0;			\
-		WARN_ON(1);				\
-		__ret = 1;				\
-	}						\
-	__ret;						\
+	if (likely(__warn_once))			\
+		if (WARN_ON(__ret_warn_once)) 		\
+			__warn_once = 0;		\
+	unlikely(__ret_warn_once);			\
 })
 
 #ifdef CONFIG_SMP

include/asm-powerpc/bug.h

@@ -70,9 +70,10 @@ struct bug_entry *find_bug(unsigned long bugaddr);
 		    "i" (__FILE__), "i" (__FUNCTION__));	\
 } while (0)
 
-#define WARN_ON(x) do {						\
-	if (__builtin_constant_p(x)) {				\
-		if (x)						\
+#define WARN_ON(x) ({						\
+	typeof(x) __ret_warn_on = (x);				\
+	if (__builtin_constant_p(__ret_warn_on)) {		\
+		if (__ret_warn_on)				\
 			__WARN();				\
 	} else {						\
 		__asm__ __volatile__(				\
@@ -80,11 +81,12 @@ struct bug_entry *find_bug(unsigned long bugaddr);
 		".section __bug_table,\"a\"\n"			\
 		"\t"PPC_LONG"	1b,%1,%2,%3\n"			\
 		".previous"					\
-		: : "r" ((long)(x)),				\
+		: : "r" (__ret_warn_on),			\
 		    "i" (__LINE__ + BUG_WARNING_TRAP),		\
 		    "i" (__FILE__), "i" (__FUNCTION__));	\
 	}							\
-} while (0)
+	unlikely(__ret_warn_on);				\
+})
 
 #define HAVE_ARCH_BUG
 #define HAVE_ARCH_BUG_ON