diff --git a/Documentation/atomic_ops.txt b/Documentation/atomic_ops.txt
index f20c10c2858..4ef24501045 100644
--- a/Documentation/atomic_ops.txt
+++ b/Documentation/atomic_ops.txt
@@ -186,7 +186,8 @@ If the atomic value v is not equal to u, this function adds a to v, and
 returns non zero. If v is equal to u then it returns zero. This is done as
 an atomic operation.
 
-atomic_add_unless requires explicit memory barriers around the operation.
+atomic_add_unless requires explicit memory barriers around the operation
+unless it fails (returns 0).
 
 atomic_inc_not_zero, equivalent to atomic_add_unless(v, 1, 0)
 
diff --git a/Documentation/memory-barriers.txt b/Documentation/memory-barriers.txt
index 4e17beba237..1f506f7830e 100644
--- a/Documentation/memory-barriers.txt
+++ b/Documentation/memory-barriers.txt
@@ -1493,7 +1493,7 @@ explicit lock operations, described later).  These include:
 	atomic_dec_and_test();
 	atomic_sub_and_test();
 	atomic_add_negative();
-	atomic_add_unless();
+	atomic_add_unless();	/* when succeeds (returns 1) */
 	test_and_set_bit();
 	test_and_clear_bit();
 	test_and_change_bit();