* [PATCH] ALSA: usb-audio: Use atomic_try_cmpxchg in ep_state_update
@ 2022-07-13 15:19 Uros Bizjak
2022-07-14 8:49 ` Takashi Iwai
0 siblings, 1 reply; 2+ messages in thread
From: Uros Bizjak @ 2022-07-13 15:19 UTC (permalink / raw)
To: alsa-devel, linux-kernel; +Cc: Uros Bizjak, Takashi Iwai
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>
Cc: 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 f9c921683948..0d7b73bf7945 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);
}
/**
--
2.35.3
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] ALSA: usb-audio: Use atomic_try_cmpxchg in ep_state_update
2022-07-13 15:19 [PATCH] ALSA: usb-audio: Use atomic_try_cmpxchg in ep_state_update Uros Bizjak
@ 2022-07-14 8:49 ` Takashi Iwai
0 siblings, 0 replies; 2+ messages in thread
From: Takashi Iwai @ 2022-07-14 8:49 UTC (permalink / raw)
To: Uros Bizjak; +Cc: alsa-devel, linux-kernel
On Wed, 13 Jul 2022 17:19:46 +0200,
Uros Bizjak wrote:
>
> 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>
> Cc: Takashi Iwai <tiwai@suse.de>
Thanks, applied.
Takashi
^ permalink raw reply [flat|nested] 2+ messages in thread
end of thread, other threads:[~2022-07-14 8:49 UTC | newest]
Thread overview: 2+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2022-07-13 15:19 [PATCH] ALSA: usb-audio: Use atomic_try_cmpxchg in ep_state_update Uros Bizjak
2022-07-14 8:49 ` Takashi Iwai
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).