UPSTREAM: ALSA: timer: Harden slave timer list handling

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

diff --git a/sound/core/timer.c b/sound/core/timer.c
index 31f40f03e5b79c8aac7cb96a793ffdd7bff94e15..8b06413e967e38a89ad5887fa78588e1e537c07c 100644 (file)
--- a/sound/core/timer.c
+++ b/sound/core/timer.c
@@ -215,11 +215,13 @@ static void snd_timer_check_master(struct snd_timer_instance *master)
                    slave->slave_id == master->slave_id) {
                        list_move_tail(&slave->open_list, &master->slave_list_head);
                        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);
                }
        }
@@ -346,15 +348,18 @@ int snd_timer_close(struct snd_timer_instance *timeri)
                    timer->hw.close)
                        timer->hw.close(timer);
                /* remove slave links */
+               spin_lock_irq(&slave_active_lock);
+               spin_lock(&timer->lock);
                list_for_each_entry_safe(slave, tmp, &timeri->slave_list_head,
                                         open_list) {
-                       spin_lock_irq(&slave_active_lock);
-                       _snd_timer_stop(slave, 1, SNDRV_TIMER_EVENT_RESOLUTION);
                        list_move_tail(&slave->open_list, &snd_timer_slave_list);
                        slave->master = NULL;
                        slave->timer = NULL;
-                       spin_unlock_irq(&slave_active_lock);
+                       list_del_init(&slave->ack_list);
+                       list_del_init(&slave->active_list);
                }
+               spin_unlock(&timer->lock);
+               spin_unlock_irq(&slave_active_lock);
                mutex_unlock(&register_mutex);
        }
  out:
@@ -441,9 +446,12 @@ static int snd_timer_start_slave(struct snd_timer_instance *timeri)
 
        spin_lock_irqsave(&slave_active_lock, flags);
        timeri->flags |= SNDRV_TIMER_IFLG_RUNNING;
-       if (timeri->master)
+       if (timeri->master && timeri->timer) {
+               spin_lock(&timeri->timer->lock);
                list_add_tail(&timeri->active_list,
                              &timeri->master->slave_active_head);
+               spin_unlock(&timeri->timer->lock);
+       }
        spin_unlock_irqrestore(&slave_active_lock, flags);
        return 1; /* delayed start */
 }
@@ -489,6 +497,8 @@ static int _snd_timer_stop(struct snd_timer_instance * timeri,
                if (!keep_flag) {
                        spin_lock_irqsave(&slave_active_lock, flags);
                        timeri->flags &= ~SNDRV_TIMER_IFLG_RUNNING;
+                       list_del_init(&timeri->ack_list);
+                       list_del_init(&timeri->active_list);
                        spin_unlock_irqrestore(&slave_active_lock, flags);
                }
                goto __end;