ALSA: Core - clean up snd_card_set_id* calls and remove possible id collision

Move locking outside snd_card_set_id_internal() function and rename it
to snd_card_set_id_no_lock() for better function description.

User defined id is just copied to card structure at allocation time.
The real unique id procedure is called in snd_card_register() to
ensure real atomicity.
Signed-off-by: NJaroslav Kysela <perex@perex.cz>
Signed-off-by: NTakashi Iwai <tiwai@suse.de>

sound/core/init.c

@@ -153,7 +153,7 @@ int snd_card_create(int idx, const char *xid,
 	if (!card)
 		return -ENOMEM;
 	if (xid)
-		snd_card_set_id(card, xid);
+		strlcpy(card->id, xid, sizeof(card->id));
 	err = 0;
 	mutex_lock(&snd_card_mutex);
 	if (idx < 0) {
@@ -476,16 +476,12 @@ int snd_card_free(struct snd_card *card)
 
 EXPORT_SYMBOL(snd_card_free);
 
-static void snd_card_set_id_internal(struct snd_card *card, const char *nid,
-				     int do_locking)
+static void snd_card_set_id_no_lock(struct snd_card *card, const char *nid)
 {
 	int i, len, idx_flag = 0, loops = SNDRV_CARDS;
 	const char *spos, *src;
 	char *id;
 	
-	/* check if user specified own card->id */
-	if (card->id[0] != '\0')
-		return;
 	if (nid == NULL) {
 		id = card->shortname;
 		spos = src = id;
@@ -522,16 +518,10 @@ static void snd_card_set_id_internal(struct snd_card *card, const char *nid,
       		}
 	      	if (!snd_info_check_reserved_words(id))
       			goto __change;
-		if (do_locking)
-			mutex_lock(&snd_card_mutex);
 		for (i = 0; i < snd_ecards_limit; i++) {
-			if (snd_cards[i] && !strcmp(snd_cards[i]->id, id)) {
-				mutex_unlock(&snd_card_mutex);
+			if (snd_cards[i] && !strcmp(snd_cards[i]->id, id))
 				goto __change;
-			}
 		}
-		if (do_locking)
-			mutex_unlock(&snd_card_mutex);
 		break;
 
 	      __change:
@@ -566,7 +556,12 @@ static void snd_card_set_id_internal(struct snd_card *card, const char *nid,
  */
 void snd_card_set_id(struct snd_card *card, const char *nid)
 {
-	snd_card_set_id_internal(card, nid, 1);
+	/* check if user specified own card->id */
+	if (card->id[0] != '\0')
+		return;
+	mutex_lock(&snd_card_mutex);
+	snd_card_set_id_no_lock(card, nid);
+	mutex_unlock(&snd_card_mutex);
 }
 EXPORT_SYMBOL(snd_card_set_id);
 
@@ -663,8 +658,7 @@ int snd_card_register(struct snd_card *card)
 		mutex_unlock(&snd_card_mutex);
 		return 0;
 	}
-	if (card->id[0] == '\0')
-		snd_card_set_id_internal(card, NULL, 0);
+	snd_card_set_id_no_lock(card, card->id[0] == '\0' ? NULL : card->id);
 	snd_cards[card->number] = card;
 	mutex_unlock(&snd_card_mutex);
 	init_info_for_card(card);