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 <ubizjak@xxxxxxxxx>
Cc: Alexander Viro <viro@xxxxxxxxxxxxxxxxxx>
Cc: Christian Brauner <brauner@xxxxxxxxxx>
Cc: Jan Kara <jack@xxxxxxx>
---
fs/super.c | 8 +++++---
1 file changed, 5 insertions(+), 3 deletions(-)
diff --git a/fs/super.c b/fs/super.c
index 7f876f32343a..e91718017701 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);
--
2.50.1
