From 89422df9548002adfffb73799cebe4909cfc8902 Mon Sep 17 00:00:00 2001
From: Uros Bizjak <ubizjak@gmail.com>
Date: Wed, 13 Jul 2022 17:19:46 +0200
Subject: [PATCH] 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>
---
sound/usb/endpoint.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/sound/usb/endpoint.c b/sound/usb/endpoint.c
index f9c921683948d..0d7b73bf79450 100644
--- 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);
}
/**
--
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