1 files changed, 72 insertions, 31 deletions

diff --git a/sound/core/seq/seq_device.c b/sound/core/seq/seq_device.c
index 91a786a783e1..0631bdadd12b 100644
--- a/sound/core/seq/seq_device.c
+++ b/sound/core/seq/seq_device.c
@@ -56,6 +56,7 @@ MODULE_LICENSE("GPL");
 #define DRIVER_LOADED		(1<<0)
 #define DRIVER_REQUESTED	(1<<1)
 #define DRIVER_LOCKED		(1<<2)
+#define DRIVER_REQUESTING	(1<<3)
 
 struct ops_list {
 	char id[ID_LEN];	/* driver id */
@@ -127,42 +128,82 @@ static void snd_seq_device_info(struct snd_info_entry *entry,
 
 #ifdef CONFIG_MODULES
 /* avoid auto-loading during module_init() */
-static int snd_seq_in_init;
+static atomic_t snd_seq_in_init = ATOMIC_INIT(1); /* blocked as default */
 void snd_seq_autoload_lock(void)
 {
-	snd_seq_in_init++;
+	atomic_inc(&snd_seq_in_init);
 }
 
 void snd_seq_autoload_unlock(void)
 {
-	snd_seq_in_init--;
+	atomic_dec(&snd_seq_in_init);
 }
-#endif
 
-void snd_seq_device_load_drivers(void)
+static void autoload_drivers(void)
 {
-#ifdef CONFIG_MODULES
-	struct ops_list *ops;
+	/* avoid reentrance */
+	if (atomic_inc_return(&snd_seq_in_init) == 1) {
+		struct ops_list *ops;
+
+		mutex_lock(&ops_mutex);
+		list_for_each_entry(ops, &opslist, list) {
+			if ((ops->driver & DRIVER_REQUESTING) &&
+			    !(ops->driver & DRIVER_REQUESTED)) {
+				ops->used++;
+				mutex_unlock(&ops_mutex);
+				ops->driver |= DRIVER_REQUESTED;
+				request_module("snd-%s", ops->id);
+				mutex_lock(&ops_mutex);
+				ops->used--;
+			}
+		}
+		mutex_unlock(&ops_mutex);
+	}
+	atomic_dec(&snd_seq_in_init);
+}
 
-	/* Calling request_module during module_init()
-	 * may cause blocking.
-	 */
-	if (snd_seq_in_init)
-		return;
+static void call_autoload(struct work_struct *work)
+{
+	autoload_drivers();
+}
 
-	mutex_lock(&ops_mutex);
-	list_for_each_entry(ops, &opslist, list) {
-		if (! (ops->driver & DRIVER_LOADED) &&
-		    ! (ops->driver & DRIVER_REQUESTED)) {
-			ops->used++;
-			mutex_unlock(&ops_mutex);
-			ops->driver |= DRIVER_REQUESTED;
-			request_module("snd-%s", ops->id);
-			mutex_lock(&ops_mutex);
-			ops->used--;
-		}
+static DECLARE_WORK(autoload_work, call_autoload);
+
+static void try_autoload(struct ops_list *ops)
+{
+	if (!ops->driver) {
+		ops->driver |= DRIVER_REQUESTING;
+		schedule_work(&autoload_work);
 	}
+}
+
+static void queue_autoload_drivers(void)
+{
+	struct ops_list *ops;
+
+	mutex_lock(&ops_mutex);
+	list_for_each_entry(ops, &opslist, list)
+		try_autoload(ops);
 	mutex_unlock(&ops_mutex);
+}
+
+void snd_seq_autoload_init(void)
+{
+	atomic_dec(&snd_seq_in_init);
+#ifdef CONFIG_SND_SEQUENCER_MODULE
+	/* initial autoload only when snd-seq is a module */
+	queue_autoload_drivers();
+#endif
+}
+#else
+#define try_autoload(ops) /* NOP */
+#endif
+
+void snd_seq_device_load_drivers(void)
+{
+#ifdef CONFIG_MODULES
+	queue_autoload_drivers();
+	flush_work(&autoload_work);
 #endif
 }
 
@@ -214,13 +255,14 @@ int snd_seq_device_new(struct snd_card *card, int device, char *id, int argsize,
 	ops->num_devices++;
 	mutex_unlock(&ops->reg_mutex);
 
-	unlock_driver(ops);
-	
 	if ((err = snd_device_new(card, SNDRV_DEV_SEQUENCER, dev, &dops)) < 0) {
 		snd_seq_device_free(dev);
 		return err;
 	}
 	
+	try_autoload(ops);
+	unlock_driver(ops);
+
 	if (result)
 		*result = dev;
 
@@ -318,16 +360,12 @@ int snd_seq_device_register_driver(char *id, struct snd_seq_dev_ops *entry,
 	    entry->init_device == NULL || entry->free_device == NULL)
 		return -EINVAL;
 
-	snd_seq_autoload_lock();
 	ops = find_driver(id, 1);
-	if (ops == NULL) {
-		snd_seq_autoload_unlock();
+	if (ops == NULL)
 		return -ENOMEM;
-	}
 	if (ops->driver & DRIVER_LOADED) {
 		pr_warn("ALSA: seq: driver_register: driver '%s' already exists\n", id);
 		unlock_driver(ops);
-		snd_seq_autoload_unlock();
 		return -EBUSY;
 	}
 
@@ -344,7 +382,6 @@ int snd_seq_device_register_driver(char *id, struct snd_seq_dev_ops *entry,
 	mutex_unlock(&ops->reg_mutex);
 
 	unlock_driver(ops);
-	snd_seq_autoload_unlock();
 
 	return 0;
 }
@@ -554,6 +591,9 @@ static int __init alsa_seq_device_init(void)
 
 static void __exit alsa_seq_device_exit(void)
 {
+#ifdef CONFIG_MODULES
+	cancel_work_sync(&autoload_work);
+#endif
 	remove_drivers();
 #ifdef CONFIG_PROC_FS
 	snd_info_free_entry(info_entry);
@@ -570,6 +610,7 @@ EXPORT_SYMBOL(snd_seq_device_new);
 EXPORT_SYMBOL(snd_seq_device_register_driver);
 EXPORT_SYMBOL(snd_seq_device_unregister_driver);
 #ifdef CONFIG_MODULES
+EXPORT_SYMBOL(snd_seq_autoload_init);
 EXPORT_SYMBOL(snd_seq_autoload_lock);
 EXPORT_SYMBOL(snd_seq_autoload_unlock);
 #endif