ALSA: Core - add snd_card_set_id() function

Introduce snd_card_set_id() function to allow lowlevel drivers to set
default identification name for card slot. The function checks also
for identification name collisions and tries to create unique name.

Also, the snd_card_create() function is simplified, because this new
function is used. As bonus, proper name collision checks are evaluated
at the card create time.

Signed-off-by: Jaroslav Kysela <perex@perex.cz>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

include/sound/core.h

@@ -313,6 +313,7 @@ struct snd_card *snd_card_new(int idx, const char *id,
 int snd_card_disconnect(struct snd_card *card);
 int snd_card_free(struct snd_card *card);
 int snd_card_free_when_closed(struct snd_card *card);
+void snd_card_set_id(struct snd_card *card, const char *id);
 int snd_card_register(struct snd_card *card);
 int snd_card_info_init(void);
 int snd_card_info_done(void);

sound/core/init.c

@@ -152,15 +152,8 @@ int snd_card_create(int idx, const char *xid,
 	card = kzalloc(sizeof(*card) + extra_size, GFP_KERNEL);
 	if (!card)
 		return -ENOMEM;
-	if (xid) {
-		if (!snd_info_check_reserved_words(xid)) {
-			snd_printk(KERN_ERR
-				   "given id string '%s' is reserved.\n", xid);
-			err = -EBUSY;
-			goto __error;
-		}
-		strlcpy(card->id, xid, sizeof(card->id));
-	}
+	if (xid)
+		snd_card_set_id(card, xid);
 	err = 0;
 	mutex_lock(&snd_card_mutex);
 	if (idx < 0) {
@@ -483,22 +476,39 @@ int snd_card_free(struct snd_card *card)
 
 EXPORT_SYMBOL(snd_card_free);
 
-static void choose_default_id(struct snd_card *card)
+/**
+ *  snd_card_set_id - set card identification name
+ *  @card: soundcard structure
+ *  @nid: new identification string
+ *
+ *  This function sets the card identification and checks for name
+ *  collisions.
+ */
+void snd_card_set_id(struct snd_card *card, const char *nid)
 {
 	int i, len, idx_flag = 0, loops = SNDRV_CARDS;
-	char *id, *spos;
+	const char *spos, *src;
+	char *id;
 
-	id = spos = card->shortname;	
-	while (*id != '\0') {
-		if (*id == ' ')
-			spos = id + 1;
-		id++;
+	/* check if user specified own card->id */
+	if (card->id[0] != '\0')
+		return;
+	if (nid == NULL) {
+		id = card->shortname;
+		spos = src = id;
+		while (*id != '\0') {
+			if (*id == ' ')
+				spos = id + 1;
+			id++;
+		}
+	} else {
+		spos = src = nid;
 	}
 	id = card->id;
 	while (*spos != '\0' && !isalnum(*spos))
 		spos++;
 	if (isdigit(*spos))
-		*id++ = isalpha(card->shortname[0]) ? card->shortname[0] : 'D';
+		*id++ = isalpha(src[0]) ? src[0] : 'D';
 	while (*spos != '\0' && (size_t)(id - card->id) < sizeof(card->id) - 1) {
 		if (isalnum(*spos))
 			*id++ = *spos;
@@ -513,16 +523,20 @@ static void choose_default_id(struct snd_card *card)
 
 	while (1) {
 	      	if (loops-- == 0) {
-      			snd_printk(KERN_ERR "unable to choose default card id (%s)\n", id);
+			snd_printk(KERN_ERR "unable to set card id (%s)\n", id);
       			strcpy(card->id, card->proc_root->name);
       			return;
       		}
 	      	if (!snd_info_check_reserved_words(id))
       			goto __change;
+		mutex_lock(&snd_card_mutex);
 		for (i = 0; i < snd_ecards_limit; i++) {
-			if (snd_cards[i] && !strcmp(snd_cards[i]->id, id))
+			if (snd_cards[i] && !strcmp(snd_cards[i]->id, id)) {
+				mutex_unlock(&snd_card_mutex);
 				goto __change;
+			}
 		}
+		mutex_unlock(&snd_card_mutex);
 		break;
 
 	      __change:
@@ -539,14 +553,16 @@ static void choose_default_id(struct snd_card *card)
 			spos = id + len - 2;
 			if ((size_t)len <= sizeof(card->id) - 2)
 				spos++;
-			*spos++ = '_';
-			*spos++ = '1';
-			*spos++ = '\0';
+			*(char *)spos++ = '_';
+			*(char *)spos++ = '1';
+			*(char *)spos++ = '\0';
 			idx_flag++;
 		}
 	}
 }
 
+EXPORT_SYMBOL(snd_card_set_id);
+
 #ifndef CONFIG_SYSFS_DEPRECATED
 static ssize_t
 card_id_show_attr(struct device *dev,
@@ -641,7 +657,7 @@ int snd_card_register(struct snd_card *card)
 		return 0;
 	}
 	if (card->id[0] == '\0')
-		choose_default_id(card);
+		snd_card_set_id(card, NULL);
 	snd_cards[card->number] = card;
 	mutex_unlock(&snd_card_mutex);
 	init_info_for_card(card);