From 10a8ebbb08c4b08292598947bbe534e04d6ee705 Mon Sep 17 00:00:00 2001 From: Jaroslav Kysela Date: Tue, 2 Jun 2009 12:02:38 +0200 Subject: 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 Signed-off-by: Takashi Iwai --- sound/core/init.c | 62 ++++++++++++++++++++++++++++++++++--------------------- 1 file changed, 39 insertions(+), 23 deletions(-) (limited to 'sound/core/init.c') diff --git a/sound/core/init.c b/sound/core/init.c index fd56afe846ed..6557dd85e191 100644 --- a/sound/core/init.c +++ b/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); -- cgit v1.2.3 From 872c78202c58d26596e25743791ee81a7d24abad Mon Sep 17 00:00:00 2001 From: Mark Brown Date: Wed, 3 Jun 2009 20:43:29 +0100 Subject: ALSA: Fix double locking of card list in snd_card_register() The introduction of snd_card_set_id() added a lock on the card list to the old choose_default_id() function when using it to implement the new API call. This lock is needed to allow us to walk the list and check to see if our new name is a duplicate. Unfortunately this causes a lockup when called from snd_card_register() (in cases where no ID is supplied for the card) since the card list is already locked there. Fix this fairly hideously by factoring out the implementation and using a flag to indicate if the lock should be held. A better fix would probably be to refactor snd_card_register() to move the _set_id() outside the locking region but I can't immediately see anything I can convince myself is safe. Signed-off-by: Mark Brown Signed-off-by: Takashi Iwai --- sound/core/init.c | 31 +++++++++++++++++++------------ 1 file changed, 19 insertions(+), 12 deletions(-) (limited to 'sound/core/init.c') diff --git a/sound/core/init.c b/sound/core/init.c index 6557dd85e191..a578d05f9e13 100644 --- a/sound/core/init.c +++ b/sound/core/init.c @@ -476,15 +476,8 @@ int snd_card_free(struct snd_card *card) EXPORT_SYMBOL(snd_card_free); -/** - * 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) +static void snd_card_set_id_internal(struct snd_card *card, const char *nid, + int do_locking) { int i, len, idx_flag = 0, loops = SNDRV_CARDS; const char *spos, *src; @@ -529,14 +522,16 @@ void snd_card_set_id(struct snd_card *card, const char *nid) } if (!snd_info_check_reserved_words(id)) goto __change; - mutex_lock(&snd_card_mutex); + 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); goto __change; } } - mutex_unlock(&snd_card_mutex); + if (do_locking) + mutex_unlock(&snd_card_mutex); break; __change: @@ -561,6 +556,18 @@ void snd_card_set_id(struct snd_card *card, const char *nid) } } +/** + * 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) +{ + snd_card_set_id_internal(card, nid, 1); +} EXPORT_SYMBOL(snd_card_set_id); #ifndef CONFIG_SYSFS_DEPRECATED @@ -657,7 +664,7 @@ int snd_card_register(struct snd_card *card) return 0; } if (card->id[0] == '\0') - snd_card_set_id(card, NULL); + snd_card_set_id_internal(card, NULL, 0); snd_cards[card->number] = card; mutex_unlock(&snd_card_mutex); init_info_for_card(card); -- cgit v1.2.3 From 5fdc18d938c99399b73fe894bc24cb9400a1a2ee Mon Sep 17 00:00:00 2001 From: Jaroslav Kysela Date: Thu, 4 Jun 2009 00:12:18 +0200 Subject: 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: Jaroslav Kysela Signed-off-by: Takashi Iwai --- sound/core/init.c | 26 ++++++++++---------------- 1 file changed, 10 insertions(+), 16 deletions(-) (limited to 'sound/core/init.c') diff --git a/sound/core/init.c b/sound/core/init.c index a578d05f9e13..d5d40d78c409 100644 --- a/sound/core/init.c +++ b/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); -- cgit v1.2.3