[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>
diff --git a/include/asm-cris/atomic.h b/include/asm-cris/atomic.h
index 8c2e783..45891f7d 100644
--- a/include/asm-cris/atomic.h
+++ b/include/asm-cris/atomic.h
@@ -123,6 +123,19 @@
return retval;
}
+static inline int atomic_cmpxchg(atomic_t *v, int old, int new)
+{
+ int ret;
+ unsigned long flags;
+
+ cris_atomic_save(v, flags);
+ ret = v->counter;
+ if (likely(ret == old))
+ v->counter = new;
+ cris_atomic_restore(v, flags);
+ return ret;
+}
+
/* Atomic operations are already serializing */
#define smp_mb__before_atomic_dec() barrier()
#define smp_mb__after_atomic_dec() barrier()