[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-v850/atomic.h b/include/asm-v850/atomic.h
index f5b9ab6..166df00 100644
--- a/include/asm-v850/atomic.h
+++ b/include/asm-v850/atomic.h
@@ -104,6 +104,8 @@
 	return ret;
 }
 
+#define atomic_xchg(v, new) (xchg(&((v)->counter), new))
+
 static inline int atomic_add_unless(atomic_t *v, int a, int u)
 {
 	int ret;