ALSA: core: Use READ_ONCE() / WRITE_ONCE() for power state change

We need proper barriers to handle the power state change of the card
from different CPUs.

Reviewed-by: Jaroslav Kysela <perex@perex.cz>
Link: https://lore.kernel.org/r/20210523090920.15345-2-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>

diff --git a/include/sound/core.h b/include/sound/core.h
index 1f9aef0..d69dfc6 100644 (file)
--- a/include/sound/core.h
+++ b/include/sound/core.h
@@ -142,12 +142,12 @@ struct snd_card {
 #ifdef CONFIG_PM
 static inline unsigned int snd_power_get_state(struct snd_card *card)
 {
-       return card->power_state;
+       return READ_ONCE(card->power_state);
 }
 
 static inline void snd_power_change_state(struct snd_card *card, unsigned int state)
 {
-       card->power_state = state;
+       WRITE_ONCE(card->power_state, state);
        wake_up(&card->power_sleep);
 }