[ALSA] Fix rwlock around snd_iprintf() in sound core

Fixed rwlock around snd_iprintf() in sound core part.
Replaced with mutex.
Also, make mutex and flags static variables with addition of
snd_card_locked() function (just for sound.c).

Signed-off-by: Takashi Iwai <tiwai@suse.de>

2 files changed, 32 insertions, 26 deletions

diff --git a/sound/core/init.c b/sound/core/init.c
index 2ff0e5e90865..38b2d4a9d672 100644
--- a/sound/core/init.c
+++ b/sound/core/init.c
@@ -38,11 +38,11 @@ struct snd_shutdown_f_ops {
         struct snd_shutdown_f_ops *next;
 };
 
-unsigned int snd_cards_lock = 0;        /* locked for registering/using */
+static unsigned int snd_cards_lock = 0; /* locked for registering/using */
 struct snd_card *snd_cards[SNDRV_CARDS] = {[0 ... (SNDRV_CARDS-1)] = NULL};
 EXPORT_SYMBOL(snd_cards);
 
-DEFINE_RWLOCK(snd_card_rwlock);
+static DEFINE_MUTEX(snd_card_mutex);
 
 #if defined(CONFIG_SND_MIXER_OSS) || defined(CONFIG_SND_MIXER_OSS_MODULE)
 int (*snd_mixer_oss_notify_callback)(struct snd_card *card, int free_flag);
@@ -112,7 +112,7 @@ struct snd_card *snd_card_new(int idx, const char *xid,
                 strlcpy(card->id, xid, sizeof(card->id));
         }
         err = 0;
-        write_lock(&snd_card_rwlock);
+        mutex_lock(&snd_card_mutex);
         if (idx < 0) {
                 int idx2;
                 for (idx2 = 0; idx2 < SNDRV_CARDS; idx2++)
@@ -130,12 +130,12 @@ struct snd_card *snd_card_new(int idx, const char *xid,
         else
                 err = -ENODEV;
         if (idx < 0 || err < 0) {
-                write_unlock(&snd_card_rwlock);
+                mutex_unlock(&snd_card_mutex);
                 snd_printk(KERN_ERR "cannot find the slot for index %d (range 0-%i)\n", idx, snd_ecards_limit - 1);
                 goto __error;
         }
         snd_cards_lock |= 1 << idx;             /* lock it */
-        write_unlock(&snd_card_rwlock);
+        mutex_unlock(&snd_card_mutex);
         card->number = idx;
         card->module = module;
         INIT_LIST_HEAD(&card->devices);
@@ -173,6 +173,17 @@ struct snd_card *snd_card_new(int idx, const char *xid,
 
 EXPORT_SYMBOL(snd_card_new);
 
+/* return non-zero if a card is already locked */
+int snd_card_locked(int card)
+{
+        int locked;
+
+        mutex_lock(&snd_card_mutex);
+        locked = snd_cards_lock & (1 << card);
+        mutex_unlock(&snd_card_mutex);
+        return locked;
+}
+
 static loff_t snd_disconnect_llseek(struct file *file, loff_t offset, int orig)
 {
         return -ENODEV;
@@ -240,9 +251,9 @@ int snd_card_disconnect(struct snd_card *card)
         spin_unlock(&card->files_lock);
 
         /* phase 1: disable fops (user space) operations for ALSA API */
-        write_lock(&snd_card_rwlock);
+        mutex_lock(&snd_card_mutex);
         snd_cards[card->number] = NULL;
-        write_unlock(&snd_card_rwlock);
+        mutex_unlock(&snd_card_mutex);
         
         /* phase 2: replace file->f_op with special dummy operations */
         
@@ -321,9 +332,9 @@ int snd_card_free(struct snd_card *card)
 
         if (card == NULL)
                 return -EINVAL;
-        write_lock(&snd_card_rwlock);
+        mutex_lock(&snd_card_mutex);
         snd_cards[card->number] = NULL;
-        write_unlock(&snd_card_rwlock);
+        mutex_unlock(&snd_card_mutex);
 
 #ifdef CONFIG_PM
         wake_up(&card->power_sleep);
@@ -359,9 +370,9 @@ int snd_card_free(struct snd_card *card)
                 card->s_f_ops = s_f_ops->next;
                 kfree(s_f_ops);
         }
-        write_lock(&snd_card_rwlock);
+        mutex_lock(&snd_card_mutex);
         snd_cards_lock &= ~(1 << card->number);
-        write_unlock(&snd_card_rwlock);
+        mutex_unlock(&snd_card_mutex);
         kfree(card);
         return 0;
 }
@@ -497,16 +508,16 @@ int snd_card_register(struct snd_card *card)
         snd_assert(card != NULL, return -EINVAL);
         if ((err = snd_device_register_all(card)) < 0)
                 return err;
-        write_lock(&snd_card_rwlock);
+        mutex_lock(&snd_card_mutex);
         if (snd_cards[card->number]) {
                 /* already registered */
-                write_unlock(&snd_card_rwlock);
+                mutex_unlock(&snd_card_mutex);
                 return 0;
         }
         if (card->id[0] == '\0')
                 choose_default_id(card);
         snd_cards[card->number] = card;
-        write_unlock(&snd_card_rwlock);
+        mutex_unlock(&snd_card_mutex);
         init_info_for_card(card);
 #if defined(CONFIG_SND_MIXER_OSS) || defined(CONFIG_SND_MIXER_OSS_MODULE)
         if (snd_mixer_oss_notify_callback)
@@ -527,7 +538,7 @@ static void snd_card_info_read(struct snd_info_entry *entry,
         struct snd_card *card;
 
         for (idx = count = 0; idx < SNDRV_CARDS; idx++) {
-                read_lock(&snd_card_rwlock);
+                mutex_lock(&snd_card_mutex);
                 if ((card = snd_cards[idx]) != NULL) {
                         count++;
                         snd_iprintf(buffer, "%2i [%-15s]: %s - %s\n",
@@ -538,7 +549,7 @@ static void snd_card_info_read(struct snd_info_entry *entry,
                         snd_iprintf(buffer, "                      %s\n",
                                         card->longname);
                 }
-                read_unlock(&snd_card_rwlock);
+                mutex_unlock(&snd_card_mutex);
         }
         if (!count)
                 snd_iprintf(buffer, "--- no soundcards ---\n");
@@ -552,12 +563,12 @@ void snd_card_info_read_oss(struct snd_info_buffer *buffer)
         struct snd_card *card;
 
         for (idx = count = 0; idx < SNDRV_CARDS; idx++) {
-                read_lock(&snd_card_rwlock);
+                mutex_lock(&snd_card_mutex);
                 if ((card = snd_cards[idx]) != NULL) {
                         count++;
                         snd_iprintf(buffer, "%s\n", card->longname);
                 }
-                read_unlock(&snd_card_rwlock);
+                mutex_unlock(&snd_card_mutex);
         }
         if (!count) {
                 snd_iprintf(buffer, "--- no soundcards ---\n");
@@ -575,11 +586,11 @@ static void snd_card_module_info_read(struct snd_info_entry *entry,
         struct snd_card *card;
 
         for (idx = 0; idx < SNDRV_CARDS; idx++) {
-                read_lock(&snd_card_rwlock);
+                mutex_lock(&snd_card_mutex);
                 if ((card = snd_cards[idx]) != NULL)
                         snd_iprintf(buffer, "%2i %s\n",
                                     idx, card->module->name);
-                read_unlock(&snd_card_rwlock);
+                mutex_unlock(&snd_card_mutex);
         }
 }
 #endif
diff --git a/sound/core/sound.c b/sound/core/sound.c
index 8313f97907d8..02c8cc4ebffe 100644
--- a/sound/core/sound.c
+++ b/sound/core/sound.c
@@ -81,14 +81,9 @@ extern struct class *sound_class;
  */
 void snd_request_card(int card)
 {
-        int locked;
-
         if (! current->fs->root)
                 return;
-        read_lock(&snd_card_rwlock);
-        locked = snd_cards_lock & (1 << card);
-        read_unlock(&snd_card_rwlock);
-        if (locked)
+        if (snd_card_locked(card))
                 return;
         if (card < 0 || card >= cards_limit)
                 return;