diff options
| -rw-r--r-- | Documentation/atomic_ops.txt | 4 | ||||
| -rw-r--r-- | Documentation/memory-barriers.txt | 6 |
2 files changed, 6 insertions, 4 deletions
diff --git a/Documentation/atomic_ops.txt b/Documentation/atomic_ops.txt index dab6da3382d9..b19fc34efdb1 100644 --- a/Documentation/atomic_ops.txt +++ b/Documentation/atomic_ops.txt @@ -266,7 +266,9 @@ with the given old and new values. Like all atomic_xxx operations, atomic_cmpxchg will only satisfy its atomicity semantics as long as all other accesses of *v are performed through atomic_xxx operations. -atomic_cmpxchg must provide explicit memory barriers around the operation. +atomic_cmpxchg must provide explicit memory barriers around the operation, +although if the comparison fails then no memory ordering guarantees are +required. The semantics for atomic_cmpxchg are the same as those defined for 'cas' below. diff --git a/Documentation/memory-barriers.txt b/Documentation/memory-barriers.txt index 13feb697271f..18fc860df1be 100644 --- a/Documentation/memory-barriers.txt +++ b/Documentation/memory-barriers.txt @@ -2383,9 +2383,7 @@ about the state (old or new) implies an SMP-conditional general memory barrier explicit lock operations, described later). These include: xchg(); - cmpxchg(); atomic_xchg(); atomic_long_xchg(); - atomic_cmpxchg(); atomic_long_cmpxchg(); atomic_inc_return(); atomic_long_inc_return(); atomic_dec_return(); atomic_long_dec_return(); atomic_add_return(); atomic_long_add_return(); @@ -2398,7 +2396,9 @@ explicit lock operations, described later). These include: test_and_clear_bit(); test_and_change_bit(); - /* when succeeds (returns 1) */ + /* when succeeds */ + cmpxchg(); + atomic_cmpxchg(); atomic_long_cmpxchg(); atomic_add_unless(); atomic_long_add_unless(); These are used for such things as implementing ACQUIRE-class and RELEASE-class |