From: Richard Braun Date: Thu, 13 Dec 2012 10:07:32 +0000 (+0100) Subject: Documentation: Memory barrier semantics of atomic_xchg() X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=7e8b1e78ea028cbd32337e2aea574a8466c796bb;p=linux-beck.git Documentation: Memory barrier semantics of atomic_xchg() Add atomic_xchg() to documentation for atomic operations and memory barriers. Signed-off-by: Richard Braun Signed-off-by: Paul E. McKenney Reviewed-by: Josh Triplett --- diff --git a/Documentation/atomic_ops.txt b/Documentation/atomic_ops.txt index 27f2b21a9d5c..d9ca5be9b471 100644 --- 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, diff --git a/Documentation/memory-barriers.txt b/Documentation/memory-barriers.txt index 3c4e1b3b80a1..fa5d8a9ae205 100644 --- a/Documentation/memory-barriers.txt +++ b/Documentation/memory-barriers.txt @@ -1685,6 +1685,7 @@ explicit lock operations, described later). These include: xchg(); cmpxchg(); + atomic_xchg(); atomic_cmpxchg(); atomic_inc_return(); atomic_dec_return();