ALSA: timer: Handle disconnection more safely

[firefly-linux-kernel-4.4.55.git] / sound / core / timer.c

diff --git a/sound/core/timer.c b/sound/core/timer.c
index 4e8d7bfffff6be48770eb9825348c8c811186d11..0a049c4578f1db0807f2bd94ed111181e18efd11 100644 (file)
--- a/sound/core/timer.c
+++ b/sound/core/timer.c
@@ -65,6 +65,7 @@ struct snd_timer_user {
        int qtail;
        int qused;
        int queue_size;
+       bool disconnected;
        struct snd_timer_read *queue;
        struct snd_timer_tread *tqueue;
        spinlock_t qlock;
@@ -290,6 +291,9 @@ int snd_timer_open(struct snd_timer_instance **ti,
                mutex_unlock(&register_mutex);
                return -ENOMEM;
        }
+       /* take a card refcount for safe disconnection */
+       if (timer->card)
+               get_device(&timer->card->card_dev);
        timeri->slave_class = tid->dev_sclass;
        timeri->slave_id = slave_id;
        if (list_empty(&timer->open_list_head) && timer->hw.open)
@@ -360,6 +364,9 @@ int snd_timer_close(struct snd_timer_instance *timeri)
                }
                spin_unlock(&timer->lock);
                spin_unlock_irq(&slave_active_lock);
+               /* release a card refcount for safe disconnection */
+               if (timer->card)
+                       put_device(&timer->card->card_dev);
                mutex_unlock(&register_mutex);
        }
  out:
@@ -475,6 +482,8 @@ int snd_timer_start(struct snd_timer_instance *timeri, unsigned int ticks)
        timer = timeri->timer;
        if (timer == NULL)
                return -EINVAL;
+       if (timer->card && timer->card->shutdown)
+               return -ENODEV;
        spin_lock_irqsave(&timer->lock, flags);
        timeri->ticks = timeri->cticks = ticks;
        timeri->pticks = 0;
@@ -509,6 +518,10 @@ static int _snd_timer_stop(struct snd_timer_instance * timeri,
        spin_lock_irqsave(&timer->lock, flags);
        list_del_init(&timeri->ack_list);
        list_del_init(&timeri->active_list);
+       if (timer->card && timer->card->shutdown) {
+               spin_unlock_irqrestore(&timer->lock, flags);
+               return 0;
+       }
        if ((timeri->flags & SNDRV_TIMER_IFLG_RUNNING) &&
            !(--timer->running)) {
                timer->hw.stop(timer);
@@ -571,6 +584,8 @@ int snd_timer_continue(struct snd_timer_instance *timeri)
        timer = timeri->timer;
        if (! timer)
                return -EINVAL;
+       if (timer->card && timer->card->shutdown)
+               return -ENODEV;
        spin_lock_irqsave(&timer->lock, flags);
        if (!timeri->cticks)
                timeri->cticks = 1;
@@ -634,6 +649,9 @@ static void snd_timer_tasklet(unsigned long arg)
        unsigned long resolution, ticks;
        unsigned long flags;
 
+       if (timer->card && timer->card->shutdown)
+               return;
+
        spin_lock_irqsave(&timer->lock, flags);
        /* now process all callbacks */
        while (!list_empty(&timer->sack_list_head)) {
@@ -674,6 +692,9 @@ void snd_timer_interrupt(struct snd_timer * timer, unsigned long ticks_left)
        if (timer == NULL)
                return;
 
+       if (timer->card && timer->card->shutdown)
+               return;
+
        spin_lock_irqsave(&timer->lock, flags);
 
        /* remember the current resolution */
@@ -884,11 +905,28 @@ static int snd_timer_dev_register(struct snd_device *dev)
        return 0;
 }
 
+/* just for reference in snd_timer_dev_disconnect() below */
+static void snd_timer_user_ccallback(struct snd_timer_instance *timeri,
+                                    int event, struct timespec *tstamp,
+                                    unsigned long resolution);
+
 static int snd_timer_dev_disconnect(struct snd_device *device)
 {
        struct snd_timer *timer = device->device_data;
+       struct snd_timer_instance *ti;
+
        mutex_lock(&register_mutex);
        list_del_init(&timer->device_list);
+       /* wake up pending sleepers */
+       list_for_each_entry(ti, &timer->open_list_head, open_list) {
+               /* FIXME: better to have a ti.disconnect() op */
+               if (ti->ccallback == snd_timer_user_ccallback) {
+                       struct snd_timer_user *tu = ti->callback_data;
+
+                       tu->disconnected = true;
+                       wake_up(&tu->qchange_sleep);
+               }
+       }
        mutex_unlock(&register_mutex);
        return 0;
 }
@@ -899,6 +937,8 @@ void snd_timer_notify(struct snd_timer *timer, int event, struct timespec *tstam
        unsigned long resolution = 0;
        struct snd_timer_instance *ti, *ts;
 
+       if (timer->card && timer->card->shutdown)
+               return;
        if (! (timer->hw.flags & SNDRV_TIMER_HW_SLAVE))
                return;
        if (snd_BUG_ON(event < SNDRV_TIMER_EVENT_MSTART ||
@@ -1057,6 +1097,8 @@ static void snd_timer_proc_read(struct snd_info_entry *entry,
 
        mutex_lock(&register_mutex);
        list_for_each_entry(timer, &snd_timer_list, device_list) {
+               if (timer->card && timer->card->shutdown)
+                       continue;
                switch (timer->tmr_class) {
                case SNDRV_TIMER_CLASS_GLOBAL:
                        snd_iprintf(buffer, "G%i: ", timer->tmr_device);
@@ -1882,6 +1924,10 @@ static ssize_t snd_timer_user_read(struct file *file, char __user *buffer,
 
                        remove_wait_queue(&tu->qchange_sleep, &wait);
 
+                       if (tu->disconnected) {
+                               err = -ENODEV;
+                               break;
+                       }
                        if (signal_pending(current)) {
                                err = -ERESTARTSYS;
                                break;
@@ -1931,6 +1977,8 @@ static unsigned int snd_timer_user_poll(struct file *file, poll_table * wait)
        mask = 0;
        if (tu->qused)
                mask |= POLLIN | POLLRDNORM;
+       if (tu->disconnected)
+               mask |= POLLERR;
 
        return mask;
 }