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Date: Sun, 10 Feb 2008 10:28:39 -0500
From: Mathieu Desnoyers <mathieu.desnoyers@...ymtl.ca>
To: Christoph Lameter <clameter@....com>
Cc: Vegard Nossum <vegard.nossum@...il.com>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
Pekka Enberg <penberg@...helsinki.fi>,
akpm@...ux-foundation.org
Subject: [PATCH] Cast cmpxchg and cmpxchg_local result for 386 and 486
Vegard Nossum <vegard.nossum@...il.com> :
> Hi,
>
> I get these warnings when compiling mm/slub.c in linux-2.6.git:
>
> 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
>
> The actual lines are calls to cmpxchg_local(). This is probably
> because I'm compiling with M386. I'm guessing the source of the
> warnings is in include/asm-x86/cmpxchg_32.h, lines 283 and 286. Config
> attached.
Christoph Lameter <clameter@....com>
Hmmm.. That cmpxchg local needs to be fixed? Mathieu?
Yes, 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@...ymtl.ca>
CC: Christoph Lameter <clameter@....com>
CC: Vegard Nossum <vegard.nossum@...il.com>
CC: Pekka Enberg <penberg@...helsinki.fi>
CC: akpm@...ux-foundation.org
---
include/asm-x86/cmpxchg_32.h | 32 ++++++++++++++++++++------------
1 file changed, 20 insertions(+), 12 deletions(-)
Index: linux-2.6-lttng/include/asm-x86/cmpxchg_32.h
===================================================================
--- linux-2.6-lttng.orig/include/asm-x86/cmpxchg_32.h 2008-02-10 06:26:50.000000000 -0500
+++ linux-2.6-lttng/include/asm-x86/cmpxchg_32.h 2008-02-10 06:41:43.000000000 -0500
@@ -269,22 +269,26 @@
({ \
__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 @@
({ \
__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 @@
({ \
__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; \
})
--
Mathieu Desnoyers
Computer Engineering Ph.D. Student, Ecole Polytechnique de Montreal
OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68
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