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authorUros Bizjak <ubizjak@gmail.com>2022-07-12 17:27:41 +0200
committerJens Axboe <axboe@kernel.dk>2022-07-12 14:39:06 -0600
commit939f9dd040fe1063d884f8f0f89b037093fe2341 (patch)
tree71f1874add6d679773e8bd0d4000690fde284f85
parentf4b1e27db49c8b985b116aa99481b4c6a4342ed4 (diff)
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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 <ubizjak@gmail.com> Cc: Jens Axboe <axboe@kernel.dk> Link: https://lore.kernel.org/r/20220712152741.7324-1-ubizjak@gmail.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
-rw-r--r--block/blk-core.c2
1 files changed, 1 insertions, 1 deletions
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) {