Messages in this thread Patch in this message | | | Date | Sun, 10 Feb 2008 10:28:39 -0500 | From | Mathieu Desnoyers <> | Subject | [PATCH] Cast cmpxchg and cmpxchg_local result for 386 and 486 |
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Vegard Nossum <vegard.nossum@gmail.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@sgi.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@polymtl.ca> CC: Christoph Lameter <clameter@sgi.com> CC: Vegard Nossum <vegard.nossum@gmail.com> CC: Pekka Enberg <penberg@cs.helsinki.fi> CC: akpm@linux-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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