Re: 2.6.18-rc1-mm2

Herbert Xu
2006-07-15T10:32:20Z

On Fri, Jul 14, 2006 at 10:40:01PM -0700, David Miller wrote:
>
> Wouldn't it be cleaner to wrap this unlikely around
> the top-level "({ })"? When it sits on a line by
> itself it looks strange, that much is true :)

Sure, in fact there was a name clash as well with __ret and
I forgot to update the arch-specific versions.

[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.

Signed-off-by: Herbert Xu herbert@gondor.apana.org.au>

Cheers,
--
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--
diff --git a/include/asm-generic/bug.h b/include/asm-generic/bug.h
index 8ceab7b..672ca90 100644
--- a/include/asm-generic/bug.h
+++ b/include/asm-generic/bug.h
@@ -16,12 +16,14 @@ #define BUG_ON(condition) do { if (unlik
#endif

#ifndef HAVE_ARCH_WARN_ON
-#define WARN_ON(condition) do { \
- if (unlikely((condition)!=0)) { \
+#define WARN_ON(condition) unlikely({ \
+ int __ret_warn_on = (condition); \
+ if (unlikely(__ret_warn_on)) { \
printk("BUG: warning at %s:%d/%s()\n", __FILE__, __LINE__, __FUNCTION__); \
dump_stack(); \
} \
-} while (0)
+ __ret_warn_on; \
+})
#endif

#else /* !CONFIG_BUG */
@@ -34,21 +36,19 @@ #define BUG_ON(condition) do { if (condi
#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) \
-({ \
+unlikely({ \
static int __warn_once = 1; \
- int __ret = 0; \
+ int __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; \
+ __ret_warn_once; \
})

#ifdef CONFIG_SMP
diff --git a/include/asm-powerpc/bug.h b/include/asm-powerpc/bug.h
index f44b529..a5f503f 100644
--- a/include/asm-powerpc/bug.h
+++ b/include/asm-powerpc/bug.h
@@ -70,9 +70,10 @@ #define __WARN() do { \
"i" (__FILE__), "i" (__FUNCTION__)); \
} while (0)

-#define WARN_ON(x) do { \
- if (__builtin_constant_p(x)) { \
- if (x) \
+#define WARN_ON(x) unlikely({ \
+ long __ret_warn_on = (x); \
+ if (__builtin_constant_p(__ret_warn_on)) { \
+ if (__ret_warn_on) \
__WARN(); \
} else { \
__asm__ __volatile__( \
@@ -80,11 +81,12 @@ #define WARN_ON(x) do { \
".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)
+ __ret_warn_on; \
+})

#define HAVE_ARCH_BUG
#define HAVE_ARCH_BUG_ON