ALSA: timer: Unify master/slave linking code

[linux.git] / sound / core / timer.c

diff --git a/sound/core/timer.c b/sound/core/timer.c
index 5c9fbf3f43407a33aeb9dcbb338d6b98c9f18dc3..21c2d25e4074aa2ac2544297ac2ed284a4548d20 100644 (file)
--- a/sound/core/timer.c
+++ b/sound/core/timer.c
@@ -74,6 +74,9 @@ static LIST_HEAD(snd_timer_slave_list);
 /* lock for slave active lists */
 static DEFINE_SPINLOCK(slave_active_lock);
 
+#define MAX_SLAVE_INSTANCES    1000
+static int num_slaves;
+
 static DEFINE_MUTEX(register_mutex);
 
 static int snd_timer_free(struct snd_timer *timer);
@@ -160,6 +163,28 @@ static void snd_timer_request(struct snd_timer_id *tid)
 
 #endif
 
+/* move the slave if it belongs to the master; return 1 if match */
+static int check_matching_master_slave(struct snd_timer_instance *master,
+                                      struct snd_timer_instance *slave)
+{
+       if (slave->slave_class != master->slave_class ||
+           slave->slave_id != master->slave_id)
+               return 0;
+       if (master->timer->num_instances >= master->timer->max_instances)
+               return -EBUSY;
+       list_move_tail(&slave->open_list, &master->slave_list_head);
+       master->timer->num_instances++;
+       spin_lock_irq(&slave_active_lock);
+       spin_lock(&master->timer->lock);
+       slave->master = master;
+       slave->timer = master->timer;
+       if (slave->flags & SNDRV_TIMER_IFLG_RUNNING)
+               list_add_tail(&slave->active_list, &master->slave_active_head);
+       spin_unlock(&master->timer->lock);
+       spin_unlock_irq(&slave_active_lock);
+       return 1;
+}
+
 /*
  * look for a master instance matching with the slave id of the given slave.
  * when found, relink the open_link of the slave.
@@ -170,27 +195,18 @@ static int snd_timer_check_slave(struct snd_timer_instance *slave)
 {
        struct snd_timer *timer;
        struct snd_timer_instance *master;
+       int err = 0;
 
        /* FIXME: it's really dumb to look up all entries.. */
        list_for_each_entry(timer, &snd_timer_list, device_list) {
                list_for_each_entry(master, &timer->open_list_head, open_list) {
-                       if (slave->slave_class == master->slave_class &&
-                           slave->slave_id == master->slave_id) {
-                               if (master->timer->num_instances >=
-                                   master->timer->max_instances)
-                                       return -EBUSY;
-                               list_move_tail(&slave->open_list,
-                                              &master->slave_list_head);
-                               master->timer->num_instances++;
-                               spin_lock_irq(&slave_active_lock);
-                               slave->master = master;
-                               slave->timer = master->timer;
-                               spin_unlock_irq(&slave_active_lock);
-                               return 0;
-                       }
+                       err = check_matching_master_slave(master, slave);
+                       if (err != 0) /* match found or error */
+                               goto out;
                }
        }
-       return 0;
+ out:
+       return err < 0 ? err : 0;
 }
 
 /*
@@ -202,31 +218,19 @@ static int snd_timer_check_slave(struct snd_timer_instance *slave)
 static int snd_timer_check_master(struct snd_timer_instance *master)
 {
        struct snd_timer_instance *slave, *tmp;
+       int err = 0;
 
        /* check all pending slaves */
        list_for_each_entry_safe(slave, tmp, &snd_timer_slave_list, open_list) {
-               if (slave->slave_class == master->slave_class &&
-                   slave->slave_id == master->slave_id) {
-                       if (master->timer->num_instances >=
-                           master->timer->max_instances)
-                               return -EBUSY;
-                       list_move_tail(&slave->open_list, &master->slave_list_head);
-                       master->timer->num_instances++;
-                       spin_lock_irq(&slave_active_lock);
-                       spin_lock(&master->timer->lock);
-                       slave->master = master;
-                       slave->timer = master->timer;
-                       if (slave->flags & SNDRV_TIMER_IFLG_RUNNING)
-                               list_add_tail(&slave->active_list,
-                                             &master->slave_active_head);
-                       spin_unlock(&master->timer->lock);
-                       spin_unlock_irq(&slave_active_lock);
-               }
+               err = check_matching_master_slave(master, slave);
+               if (err < 0)
+                       break;
        }
-       return 0;
+       return err < 0 ? err : 0;
 }
 
-static int snd_timer_close_locked(struct snd_timer_instance *timeri);
+static int snd_timer_close_locked(struct snd_timer_instance *timeri,
+                                 struct device **card_devp_to_put);
 
 /*
  * open a timer instance
@@ -238,6 +242,7 @@ int snd_timer_open(struct snd_timer_instance **ti,
 {
        struct snd_timer *timer;
        struct snd_timer_instance *timeri = NULL;
+       struct device *card_dev_to_put = NULL;
        int err;
 
        mutex_lock(&register_mutex);
@@ -250,6 +255,10 @@ int snd_timer_open(struct snd_timer_instance **ti,
                        err = -EINVAL;
                        goto unlock;
                }
+               if (num_slaves >= MAX_SLAVE_INSTANCES) {
+                       err = -EBUSY;
+                       goto unlock;
+               }
                timeri = snd_timer_instance_new(owner, NULL);
                if (!timeri) {
                        err = -ENOMEM;
@@ -259,9 +268,10 @@ int snd_timer_open(struct snd_timer_instance **ti,
                timeri->slave_id = tid->device;
                timeri->flags |= SNDRV_TIMER_IFLG_SLAVE;
                list_add_tail(&timeri->open_list, &snd_timer_slave_list);
+               num_slaves++;
                err = snd_timer_check_slave(timeri);
                if (err < 0) {
-                       snd_timer_close_locked(timeri);
+                       snd_timer_close_locked(timeri, &card_dev_to_put);
                        timeri = NULL;
                }
                goto unlock;
@@ -282,11 +292,11 @@ int snd_timer_open(struct snd_timer_instance **ti,
                goto unlock;
        }
        if (!list_empty(&timer->open_list_head)) {
-               timeri = list_entry(timer->open_list_head.next,
+               struct snd_timer_instance *t =
+                       list_entry(timer->open_list_head.next,
                                    struct snd_timer_instance, open_list);
-               if (timeri->flags & SNDRV_TIMER_IFLG_EXCLUSIVE) {
+               if (t->flags & SNDRV_TIMER_IFLG_EXCLUSIVE) {
                        err = -EBUSY;
-                       timeri = NULL;
                        goto unlock;
                }
        }
@@ -313,7 +323,7 @@ int snd_timer_open(struct snd_timer_instance **ti,
                        timeri = NULL;
 
                        if (timer->card)
-                               put_device(&timer->card->card_dev);
+                               card_dev_to_put = &timer->card->card_dev;
                        module_put(timer->module);
                        goto unlock;
                }
@@ -323,12 +333,15 @@ int snd_timer_open(struct snd_timer_instance **ti,
        timer->num_instances++;
        err = snd_timer_check_master(timeri);
        if (err < 0) {
-               snd_timer_close_locked(timeri);
+               snd_timer_close_locked(timeri, &card_dev_to_put);
                timeri = NULL;
        }
 
  unlock:
        mutex_unlock(&register_mutex);
+       /* put_device() is called after unlock for avoiding deadlock */
+       if (card_dev_to_put)
+               put_device(card_dev_to_put);
        *ti = timeri;
        return err;
 }
@@ -338,7 +351,8 @@ EXPORT_SYMBOL(snd_timer_open);
  * close a timer instance
  * call this with register_mutex down.
  */
-static int snd_timer_close_locked(struct snd_timer_instance *timeri)
+static int snd_timer_close_locked(struct snd_timer_instance *timeri,
+                                 struct device **card_devp_to_put)
 {
        struct snd_timer *timer = timeri->timer;
        struct snd_timer_instance *slave, *tmp;
@@ -350,6 +364,8 @@ static int snd_timer_close_locked(struct snd_timer_instance *timeri)
        }
 
        list_del(&timeri->open_list);
+       if (timeri->flags & SNDRV_TIMER_IFLG_SLAVE)
+               num_slaves--;
 
        /* force to stop the timer */
        snd_timer_stop(timeri);
@@ -395,7 +411,7 @@ static int snd_timer_close_locked(struct snd_timer_instance *timeri)
                        timer->hw.close(timer);
                /* release a card refcount for safe disconnection */
                if (timer->card)
-                       put_device(&timer->card->card_dev);
+                       *card_devp_to_put = &timer->card->card_dev;
                module_put(timer->module);
        }
 
@@ -407,14 +423,18 @@ static int snd_timer_close_locked(struct snd_timer_instance *timeri)
  */
 int snd_timer_close(struct snd_timer_instance *timeri)
 {
+       struct device *card_dev_to_put = NULL;
        int err;
 
        if (snd_BUG_ON(!timeri))
                return -ENXIO;
 
        mutex_lock(&register_mutex);
-       err = snd_timer_close_locked(timeri);
+       err = snd_timer_close_locked(timeri, &card_dev_to_put);
        mutex_unlock(&register_mutex);
+       /* put_device() is called after unlock for avoiding deadlock */
+       if (card_dev_to_put)
+               put_device(card_dev_to_put);
        return err;
 }
 EXPORT_SYMBOL(snd_timer_close);