Skip to content
Commit f4b1e27d authored by Uros Bizjak's avatar Uros Bizjak Committed by Jens Axboe
Browse files

block/rq_qos: Use atomic_try_cmpxchg in atomic_inc_below



Use atomic_try_cmpxchg instead of atomic_cmpxchg (*ptr, old, new) == old in
atomic_inc_below. 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_try_cmpxchg implicitly assigns old *ptr value to "old" when
cmpxchg fails, enabling further code simplifications.

No functional change intended.

Signed-off-by: default avatarUros Bizjak <ubizjak@gmail.com>
Cc: Jens Axboe <axboe@kernel.dk>
Link: https://lore.kernel.org/r/20220712150547.5786-1-ubizjak@gmail.com


Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent f3ec5d11
0% or .
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment