Use try_cmpxchg instead of cmpxchg (*ptr, old, new) == old
in list_add_tail_lockless. x86 CMPXCHG instruction returns
success in ZF flag, so this change saves a compare after
cmpxchg (and related move instruction in front of cmpxchg).
No functional change intended.
Signed-off-by: Uros Bizjak <[email protected]>
Cc: Alexander Viro <[email protected]>
---
fs/eventpoll.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/fs/eventpoll.c b/fs/eventpoll.c
index e2daa940ebce..6705cb965fbe 100644
--- a/fs/eventpoll.c
+++ b/fs/eventpoll.c
@@ -1065,7 +1065,7 @@ static inline bool list_add_tail_lockless(struct list_head *new,
* added to the list from another CPU: the winner observes
* new->next == new.
*/
- if (cmpxchg(&new->next, new, head) != new)
+ if (!try_cmpxchg(&new->next, &new, head))
return false;
/*
--
2.35.3