From 939f9dd040fe1063d884f8f0f89b037093fe2341 Mon Sep 17 00:00:00 2001 From: Uros Bizjak Date: Tue, 12 Jul 2022 17:27:41 +0200 Subject: block: Use try_cmpxchg in update_io_ticks Use try_cmpxchg instead of cmpxchg (*ptr, old, new) == old in update_io_ticks. 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 Cc: Jens Axboe Link: https://lore.kernel.org/r/20220712152741.7324-1-ubizjak@gmail.com Signed-off-by: Jens Axboe --- block/blk-core.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'block/blk-core.c') diff --git a/block/blk-core.c b/block/blk-core.c index b530ce7b370c..8365996a8ef8 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -943,7 +943,7 @@ void update_io_ticks(struct block_device *part, unsigned long now, bool end) again: stamp = READ_ONCE(part->bd_stamp); if (unlikely(time_after(now, stamp))) { - if (likely(cmpxchg(&part->bd_stamp, stamp, now) == stamp)) + if (likely(try_cmpxchg(&part->bd_stamp, &stamp, now))) __part_stat_add(part, io_ticks, end ? now - stamp : 1); } if (part->bd_partno) { -- cgit