Documentation: Memory barrier semantics of atomic_xchg()

[linux-2.6-block.git] / Documentation / atomic_ops.txt

diff --git a/Documentation/atomic_ops.txt b/Documentation/atomic_ops.txt
index 27f2b21a9d5cd5e040da0ab0e9cb9abbb69296a6..d9ca5be9b471d18d7c2640625d4845f9da8ff23a 100644 (file)
--- a/Documentation/atomic_ops.txt
+++ b/Documentation/atomic_ops.txt
@@ -253,6 +253,8 @@ This performs an atomic exchange operation on the atomic variable v, setting
 the given new value.  It returns the old value that the atomic variable v had
 just before the operation.
 
+atomic_xchg requires explicit memory barriers around the operation.
+
        int atomic_cmpxchg(atomic_t *v, int old, int new);
 
 This performs an atomic compare exchange operation on the atomic value v,