path: root/Documentation/atomic_t.txt
diff options
authorPeter Zijlstra <>2019-05-24 13:52:31 +0200
committerIngo Molnar <>2019-06-03 12:32:57 +0200
commitfff9b6c7d26943a8eb32b58364b7ec6b9369746a (patch)
tree54d08e55187dcb948012ad5948e4b6e25621351b /Documentation/atomic_t.txt
parent6a6a9d5fb9f26d2c2127497f3a42adbeb5ccc2a4 (diff)
Documentation/atomic_t.txt: Clarify pure non-rmw usage
Clarify that pure non-RMW usage of atomic_t is pointless, there is nothing 'magical' about atomic_set() / atomic_read(). This is something that seems to confuse people, because I happen upon it semi-regularly. Signed-off-by: Peter Zijlstra (Intel) <> Reviewed-by: Greg Kroah-Hartman <> Acked-by: Will Deacon <> Cc: Linus Torvalds <> Cc: Peter Zijlstra <> Cc: Thomas Gleixner <> Link: Signed-off-by: Ingo Molnar <>
Diffstat (limited to 'Documentation/atomic_t.txt')
1 files changed, 4 insertions, 2 deletions
diff --git a/Documentation/atomic_t.txt b/Documentation/atomic_t.txt
index dca3fb0554db..89eae7f6b360 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