[PATCH] atomic: cmpxchg

Introduce an atomic_cmpxchg operation.

Signed-off-by: Nick Piggin <npiggin@suse.de>
Cc: "Paul E. McKenney" <paulmck@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 2 insertions, 0 deletions

diff --git a/include/asm-sparc64/atomic.h b/include/asm-sparc64/atomic.h
index e175afcf2cde..3a0b4383bbac 100644
--- a/include/asm-sparc64/atomic.h
+++ b/include/asm-sparc64/atomic.h
@@ -70,6 +70,8 @@ extern int atomic64_sub_ret(int, atomic64_t *);
 #define atomic_add_negative(i, v) (atomic_add_ret(i, v) < 0)
 #define atomic64_add_negative(i, v) (atomic64_add_ret(i, v) < 0)
 
+#define atomic_cmpxchg(v, o, n) ((int)cmpxchg(&((v)->counter), (o), (n)))
+
 /* Atomic operations are already serializing */
 #ifdef CONFIG_SMP
 #define smp_mb__before_atomic_dec()     membar_storeload_loadload();