ALSA: usb-audio: Use atomic_try_cmpxchg in ep_state_update

Use atomic_try_cmpxchg instead of atomic_cmpxchg (*ptr, old, new) == old in
ep_state_update. 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>
Link: https://lore.kernel.org/r/20220713151946.4743-1-ubizjak@gmail.com
Signed-off-by: Takashi Iwai <tiwai@suse.de>

diff --git a/sound/usb/endpoint.c b/sound/usb/endpoint.c
index f9c921683948d1b8e45db3a1773161960495826f..0d7b73bf7945063cda7bd50d81c65327dde5ef2a 100644 (file)
--- a/sound/usb/endpoint.c
+++ b/sound/usb/endpoint.c
@@ -133,7 +133,7 @@ static inline bool ep_state_running(struct snd_usb_endpoint *ep)
 
 static inline bool ep_state_update(struct snd_usb_endpoint *ep, int old, int new)
 {
-       return atomic_cmpxchg(&ep->state, old, new) == old;
+       return atomic_try_cmpxchg(&ep->state, &old, new);
 }
 
 /**