x86: cast cmpxchg and cmpxchg_local result for 386 and 486

mm/slub.c: In function 'slab_alloc':
mm/slub.c:1637: warning: assignment makes pointer from integer without a cast
mm/slub.c:1637: warning: assignment makes pointer from integer without a cast
mm/slub.c: In function 'slab_free':
mm/slub.c:1796: warning: assignment makes pointer from integer without a cast
mm/slub.c:1796: warning: assignment makes pointer from integer without a cast

A cast is needed in the 386 and 486 code because the type is a pointer.  In
every other integer case the original cmpxchg code (and the cmpxchg_local
which has been copied from it) worked fine, but since we touch a pointer,
the type needs to be casted in the cmpxchg_local and cmpxchg macros.

The more recent code (586+) does not have this problem (the cast is already
there).

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Christoph Lameter <clameter@sgi.com>
Cc: Vegard Nossum <vegard.nossum@gmail.com>
Cc: Pekka Enberg <penberg@cs.helsinki.fi>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

include/asm-x86/cmpxchg_32.h

@@ -269,22 +269,26 @@ static inline unsigned long cmpxchg_386(volatile void *ptr, unsigned long old,
 ({									\
 	__typeof__(*(ptr)) __ret;					\
 	if (likely(boot_cpu_data.x86 > 3))				\
-		__ret = __cmpxchg((ptr), (unsigned long)(o),		\
-					(unsigned long)(n), sizeof(*(ptr))); \
+		__ret = (__typeof__(*(ptr)))__cmpxchg((ptr),		\
+				(unsigned long)(o), (unsigned long)(n),	\
+				sizeof(*(ptr)));			\
 	else								\
-		__ret = cmpxchg_386((ptr), (unsigned long)(o),		\
-					(unsigned long)(n), sizeof(*(ptr))); \
+		__ret = (__typeof__(*(ptr)))cmpxchg_386((ptr),		\
+				(unsigned long)(o), (unsigned long)(n),	\
+				sizeof(*(ptr)));			\
 	__ret;								\
 })
 #define cmpxchg_local(ptr, o, n)					\
 ({									\
 	__typeof__(*(ptr)) __ret;					\
 	if (likely(boot_cpu_data.x86 > 3))				\
-		__ret = __cmpxchg_local((ptr), (unsigned long)(o),	\
-					(unsigned long)(n), sizeof(*(ptr))); \
+		__ret = (__typeof__(*(ptr)))__cmpxchg_local((ptr),	\
+				(unsigned long)(o), (unsigned long)(n),	\
+				sizeof(*(ptr)));			\
 	else								\
-		__ret = cmpxchg_386((ptr), (unsigned long)(o),		\
-					(unsigned long)(n), sizeof(*(ptr))); \
+		__ret = (__typeof__(*(ptr)))cmpxchg_386((ptr),		\
+				(unsigned long)(o), (unsigned long)(n),	\
+				sizeof(*(ptr)));			\
 	__ret;								\
 })
 #endif
@@ -301,10 +305,12 @@ extern unsigned long long cmpxchg_486_u64(volatile void *, u64, u64);
 ({									\
 	__typeof__(*(ptr)) __ret;					\
 	if (likely(boot_cpu_data.x86 > 4))				\
-		__ret = __cmpxchg64((ptr), (unsigned long long)(o),	\
+		__ret = (__typeof__(*(ptr)))__cmpxchg64((ptr),		\
+				(unsigned long long)(o),		\
 				(unsigned long long)(n));		\
 	else								\
-		__ret = cmpxchg_486_u64((ptr), (unsigned long long)(o),	\
+		__ret = (__typeof__(*(ptr)))cmpxchg_486_u64((ptr),	\
+				(unsigned long long)(o),		\
 				(unsigned long long)(n));		\
 	__ret;								\
 })
@@ -312,10 +318,12 @@ extern unsigned long long cmpxchg_486_u64(volatile void *, u64, u64);
 ({									\
 	__typeof__(*(ptr)) __ret;					\
 	if (likely(boot_cpu_data.x86 > 4))				\
-		__ret = __cmpxchg64_local((ptr), (unsigned long long)(o), \
+		__ret = (__typeof__(*(ptr)))__cmpxchg64_local((ptr),	\
+				(unsigned long long)(o),		\
 				(unsigned long long)(n));		\
 	else								\
-		__ret = cmpxchg_486_u64((ptr), (unsigned long long)(o),	\
+		__ret = (__typeof__(*(ptr)))cmpxchg_486_u64((ptr),	\
+				(unsigned long long)(o),		\
 				(unsigned long long)(n));		\
 	__ret;								\
 })