From ec6f613ef376410753173f8236bad5f07a86503a Mon Sep 17 00:00:00 2001 From: Uros Bizjak Date: Mon, 11 Aug 2025 15:23:03 +0200 Subject: [PATCH] fs: Use try_cmpxchg() in sb_init_done_wq() Use !try_cmpxchg() instead of cmpxchg(*ptr, old, new) != old. The x86 CMPXCHG instruction returns success in the ZF flag, so this change saves a compare after CMPXCHG. No functional change intended. Signed-off-by: Uros Bizjak Link: https://lore.kernel.org/20250811132326.620521-1-ubizjak@gmail.com Reviewed-by: Jan Kara Cc: Alexander Viro Cc: Christian Brauner Cc: Jan Kara Signed-off-by: Christian Brauner --- fs/super.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/fs/super.c b/fs/super.c index 7f876f32343ad..e917180177018 100644 --- a/fs/super.c +++ b/fs/super.c @@ -2318,13 +2318,15 @@ int sb_init_dio_done_wq(struct super_block *sb) sb->s_id); if (!wq) return -ENOMEM; + + old = NULL; /* * This has to be atomic as more DIOs can race to create the workqueue */ - old = cmpxchg(&sb->s_dio_done_wq, NULL, wq); - /* Someone created workqueue before us? Free ours... */ - if (old) + if (!try_cmpxchg(&sb->s_dio_done_wq, &old, wq)) { + /* Someone created workqueue before us? Free ours... */ destroy_workqueue(wq); + } return 0; } EXPORT_SYMBOL_GPL(sb_init_dio_done_wq); -- 2.47.3