diff options
| author | Uros Bizjak <ubizjak@gmail.com> | 2022-09-08 17:12:00 +0200 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2022-09-08 09:22:42 -0600 |
| commit | c35227d4e8cbc70a6622cc7cc5f8c3bff513f1fa (patch) | |
| tree | 2cf72382f2a2bbedf515081f5fb6d4513742b82a /block/bio.c | |
| parent | 1de7c3cf48fc41cd95adb12bd1ea9033a917798a (diff) | |
| download | lwn-c35227d4e8cbc70a6622cc7cc5f8c3bff513f1fa.tar.gz lwn-c35227d4e8cbc70a6622cc7cc5f8c3bff513f1fa.zip | |
sbitmap: Use atomic_long_try_cmpxchg in __sbitmap_queue_get_batch
Use atomic_long_try_cmpxchg instead of
atomic_long_cmpxchg (*ptr, old, new) == old in __sbitmap_queue_get_batch.
x86 CMPXCHG instruction returns success in ZF flag, so this change
saves a compare after cmpxchg (and related move instruction in front
of cmpxchg).
Also, atomic_long_cmpxchg implicitly assigns old *ptr value to "old"
when cmpxchg fails, enabling further code simplifications, e.g.
an extra memory read can be avoided in the loop.
No functional change intended.
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Uros Bizjak <ubizjak@gmail.com>
Link: https://lore.kernel.org/r/20220908151200.9993-1-ubizjak@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'block/bio.c')
0 files changed, 0 insertions, 0 deletions