diff options
Diffstat (limited to 'Documentation/atomic_t.txt')
| -rw-r--r-- | Documentation/atomic_t.txt | 9 |
1 files changed, 7 insertions, 2 deletions
diff --git a/Documentation/atomic_t.txt b/Documentation/atomic_t.txt index b3afe69d03a1..0ab747e0d5ac 100644 --- a/Documentation/atomic_t.txt +++ b/Documentation/atomic_t.txt @@ -81,9 +81,11 @@ Non-RMW ops: The non-RMW ops are (typically) regular LOADs and STOREs and are canonically implemented using READ_ONCE(), WRITE_ONCE(), smp_load_acquire() and -smp_store_release() respectively. +smp_store_release() respectively. Therefore, if you find yourself only using +the Non-RMW operations of atomic_t, you do not in fact need atomic_t at all +and are doing it wrong. -The one detail to this is that atomic_set{}() should be observable to the RMW +A subtle detail of atomic_set{}() is that it should be observable to the RMW ops. That is: C atomic-set @@ -200,6 +202,9 @@ These helper barriers exist because architectures have varying implicit ordering on their SMP atomic primitives. For example our TSO architectures provide full ordered atomics and these barriers are no-ops. +NOTE: when the atomic RmW ops are fully ordered, they should also imply a +compiler barrier. + Thus: atomic_fetch_add(); |