[PATCH] mutex subsystem, add atomic_xchg() to all arches

add atomic_xchg() to all the architectures. Needed by the new mutex code.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Arjan van de Ven <arjan@infradead.org>
diff --git a/include/asm-frv/atomic.h b/include/asm-frv/atomic.h
index 9c9e949..a59f684 100644
--- a/include/asm-frv/atomic.h
+++ b/include/asm-frv/atomic.h
@@ -328,6 +328,7 @@
 #endif
 
 #define atomic_cmpxchg(v, old, new) (cmpxchg(&((v)->counter), old, new))
+#define atomic_xchg(v, new) (xchg(&((v)->counter), new))
 
 #define atomic_add_unless(v, a, u)				\
 ({								\