ALSA: core: Make snd_card_disconnect() return void

All callers from other files ignore the return value of this function.
And it can only ever return a non-zero value if the parameter card is NULL.

Move the check for card being NULL into snd_card_free_when_closed() to keep
the previous behaviour. Note this isn't necessary for
snd_card_disconnect_sync() because if card was NULL in there the dereference
of card for dev_err() would oops the kernel. Replace this by an oops
triggered by the dereference of card for spin_lock_irq().
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Reviewed-by: Jaroslav Kysela <perex@perex.cz>
Reviewed-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Acked-by: Geoff Levand <geoff@infradead.org>
Acked-by: Thierry Reding <treding@nvidia.com>
Link: https://lore.kernel.org/r/20230207191907.467756-2-u.kleine-koenig@pengutronix.deSigned-off-by: Takashi Iwai <tiwai@suse.de>

include/sound/core.h

@@ -286,7 +286,7 @@ int snd_devm_card_new(struct device *parent, int idx, const char *xid,
 		      struct module *module, size_t extra_size,
 		      struct snd_card **card_ret);
 
-int snd_card_disconnect(struct snd_card *card);
+void snd_card_disconnect(struct snd_card *card);
 void snd_card_disconnect_sync(struct snd_card *card);
 int snd_card_free(struct snd_card *card);
 int snd_card_free_when_closed(struct snd_card *card);

sound/core/init.c

@@ -489,17 +489,17 @@ static const struct file_operations snd_shutdown_f_ops =
  *  Note: The current implementation replaces all active file->f_op with special
  *        dummy file operations (they do nothing except release).
  */
-int snd_card_disconnect(struct snd_card *card)
+void snd_card_disconnect(struct snd_card *card)
 {
 	struct snd_monitor_file *mfile;
 
 	if (!card)
-		return -EINVAL;
+		return;
 
 	spin_lock(&card->files_lock);
 	if (card->shutdown) {
 		spin_unlock(&card->files_lock);
-		return 0;
+		return;
 	}
 	card->shutdown = 1;
 
@@ -548,7 +548,6 @@ int snd_card_disconnect(struct snd_card *card)
 	wake_up(&card->power_sleep);
 	snd_power_sync_ref(card);
 #endif
-	return 0;	
 }
 EXPORT_SYMBOL(snd_card_disconnect);
 
@@ -563,15 +562,7 @@ EXPORT_SYMBOL(snd_card_disconnect);
  */
 void snd_card_disconnect_sync(struct snd_card *card)
 {
-	int err;
-
-	err = snd_card_disconnect(card);
-	if (err < 0) {
-		dev_err(card->dev,
-			"snd_card_disconnect error (%d), skipping sync\n",
-			err);
-		return;
-	}
+	snd_card_disconnect(card);
 
 	spin_lock_irq(&card->files_lock);
 	wait_event_lock_irq(card->remove_sleep,
@@ -619,9 +610,10 @@ static int snd_card_do_free(struct snd_card *card)
  */
 int snd_card_free_when_closed(struct snd_card *card)
 {
-	int ret = snd_card_disconnect(card);
-	if (ret)
-		return ret;
+	if (!card)
+		return -EINVAL;
+
+	snd_card_disconnect(card);
 	put_device(&card->card_dev);
 	return 0;
 }