[RFC PATCH 1/4] asm-generic: cmpxchg: implement dummy cmpxchg64_relaxed operation

[Will Deacon]

cmpxchg64_relaxed can be used to provide barrier-less semantics for a
64-bit cmpxchg operation in cases where the strong memory ordering is
not required.

This patch implements a dummy implementation for asm-generic, falling
back to the usual cmpxchg64 code.

Cc: Arnd Bergmann <arnd@xxxxxxxx>
Signed-off-by: Will Deacon <will.deacon@xxxxxxx>
---
 include/asm-generic/cmpxchg.h | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/include/asm-generic/cmpxchg.h b/include/asm-generic/cmpxchg.h
index 811fb1e..298b9d4 100644
--- a/include/asm-generic/cmpxchg.h
+++ b/include/asm-generic/cmpxchg.h
@@ -102,7 +102,8 @@ unsigned long __xchg(unsigned long x, volatile void *ptr, int size)
 #define cmpxchg64_local(ptr, o, n) __cmpxchg64_local_generic((ptr), (o), (n))
 #endif
 
-#define cmpxchg(ptr, o, n)	cmpxchg_local((ptr), (o), (n))
-#define cmpxchg64(ptr, o, n)	cmpxchg64_local((ptr), (o), (n))
+#define cmpxchg(ptr, o, n)		cmpxchg_local((ptr), (o), (n))
+#define cmpxchg64(ptr, o, n)		cmpxchg64_local((ptr), (o), (n))
+#define cmpxchg64_relaxed(ptr, o, n)	cmpxchg64((ptr), (o), (n))
 
 #endif /* __ASM_GENERIC_CMPXCHG_H */
-- 
1.8.2.2

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/