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| author | Jan Beulich <JBeulich@suse.com> | 2012-01-02 17:02:18 +0000 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2012-01-04 15:01:54 +0100 |
| commit | cdcd629869fabcd38ebd24a03b0a05ec1cbcafb0 (patch) | |
| tree | 461087dd5b3d310a7da25021cb4f58270cbb7177 /arch/x86/include/asm/cmpxchg.h | |
| parent | adaf4ed2abbd285c93808060924eeec3af483aee (diff) | |
| download | linux-cdcd629869fabcd38ebd24a03b0a05ec1cbcafb0.tar.gz | |
x86: Fix and improve cmpxchg_double{,_local}()
Just like the per-CPU ones they had several problems/shortcomings: Only the first memory operand was mentioned in the asm() operands, and the 2x64-bit version didn't have a memory clobber while the 2x32-bit one did. The former allowed the compiler to not recognize the need to re-load the data in case it had it cached in some register, while the latter was overly destructive. The types of the local copies of the old and new values were incorrect (the types of the pointed-to variables should be used here, to make sure the respective old/new variable types are compatible). The __dummy/__junk variables were pointless, given that local copies of the inputs already existed (and can hence be used for discarded outputs). The 32-bit variant of cmpxchg_double_local() referenced cmpxchg16b_local(). At once also: - change the return value type to what it really is: 'bool' - unify 32- and 64-bit variants - abstract out the common part of the 'normal' and 'local' variants Signed-off-by: Jan Beulich <jbeulich@suse.com> Cc: Christoph Lameter <cl@linux.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Andrew Morton <akpm@linux-foundation.org> Link: http://lkml.kernel.org/r/4F01F12A020000780006A19B@nat28.tlf.novell.com Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'arch/x86/include/asm/cmpxchg.h')
| -rw-r--r-- | arch/x86/include/asm/cmpxchg.h | 23 |
1 files changed, 23 insertions, 0 deletions
diff --git a/arch/x86/include/asm/cmpxchg.h b/arch/x86/include/asm/cmpxchg.h index 5488e10b9dba..0c9fa2745f13 100644 --- a/arch/x86/include/asm/cmpxchg.h +++ b/arch/x86/include/asm/cmpxchg.h @@ -207,4 +207,27 @@ extern void __add_wrong_size(void) #define add_smp(ptr, inc) __add((ptr), (inc), LOCK_PREFIX) #define add_sync(ptr, inc) __add((ptr), (inc), "lock; ") +#define __cmpxchg_double(pfx, p1, p2, o1, o2, n1, n2) \ +({ \ + bool __ret; \ + __typeof__(*(p1)) __old1 = (o1), __new1 = (n1); \ + __typeof__(*(p2)) __old2 = (o2), __new2 = (n2); \ + BUILD_BUG_ON(sizeof(*(p1)) != sizeof(long)); \ + BUILD_BUG_ON(sizeof(*(p2)) != sizeof(long)); \ + VM_BUG_ON((unsigned long)(p1) % (2 * sizeof(long))); \ + VM_BUG_ON((unsigned long)((p1) + 1) != (unsigned long)(p2)); \ + asm volatile(pfx "cmpxchg%c4b %2; sete %0" \ + : "=a" (__ret), "+d" (__old2), \ + "+m" (*(p1)), "+m" (*(p2)) \ + : "i" (2 * sizeof(long)), "a" (__old1), \ + "b" (__new1), "c" (__new2)); \ + __ret; \ +}) + +#define cmpxchg_double(p1, p2, o1, o2, n1, n2) \ + __cmpxchg_double(LOCK_PREFIX, p1, p2, o1, o2, n1, n2) + +#define cmpxchg_double_local(p1, p2, o1, o2, n1, n2) \ + __cmpxchg_double(, p1, p2, o1, o2, n1, n2) + #endif /* ASM_X86_CMPXCHG_H */ |