Messages in this thread Patch in this message | | | From | Uros Bizjak <> | Subject | [PATCH] llist: Avoid extra memory read in llist_add_batch | Date | Mon, 17 Oct 2022 16:52:26 +0200 |
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try_cmpxchg implicitly assigns old head->first value to "first" when cmpxchg fails. There is no need to re-read the value in the loop.
Cc: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Uros Bizjak <ubizjak@gmail.com> --- lib/llist.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/lib/llist.c b/lib/llist.c index 7d78b736e8af..6e668fa5a2c6 100644 --- a/lib/llist.c +++ b/lib/llist.c @@ -26,10 +26,10 @@ bool llist_add_batch(struct llist_node *new_first, struct llist_node *new_last, struct llist_head *head) { - struct llist_node *first; + struct llist_node *first = READ_ONCE(head->first); do { - new_last->next = first = READ_ONCE(head->first); + new_last->next = first; } while (!try_cmpxchg(&head->first, &first, new_first)); return !first; -- 2.37.3
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