1 files changed, 53 insertions, 23 deletions

diff --git a/sound/usb/card.c b/sound/usb/card.c
index 0450593980fd..86cf7b585e01 100644
--- a/sound/usb/card.c
+++ b/sound/usb/card.c
@@ -365,13 +365,15 @@ static int snd_usb_audio_create(struct usb_interface *intf,
 	}
 
 	mutex_init(&chip->mutex);
-	init_rwsem(&chip->shutdown_rwsem);
+	init_waitqueue_head(&chip->shutdown_wait);
 	chip->index = idx;
 	chip->dev = dev;
 	chip->card = card;
 	chip->setup = device_setup[idx];
 	chip->autoclock = autoclock;
 	chip->probing = 1;
+	atomic_set(&chip->usage_count, 0);
+	atomic_set(&chip->shutdown, 0);
 
 	chip->usb_id = USB_ID(le16_to_cpu(dev->descriptor.idVendor),
 			      le16_to_cpu(dev->descriptor.idProduct));
@@ -495,7 +497,7 @@ static int usb_audio_probe(struct usb_interface *intf,
 	mutex_lock(&register_mutex);
 	for (i = 0; i < SNDRV_CARDS; i++) {
 		if (usb_chip[i] && usb_chip[i]->dev == dev) {
-			if (usb_chip[i]->shutdown) {
+			if (atomic_read(&usb_chip[i]->shutdown)) {
 				dev_err(&dev->dev, "USB device is in the shutdown state, cannot create a card instance\n");
 				err = -EIO;
 				goto __error;
@@ -585,23 +587,23 @@ static void usb_audio_disconnect(struct usb_interface *intf)
 	struct snd_usb_audio *chip = usb_get_intfdata(intf);
 	struct snd_card *card;
 	struct list_head *p;
-	bool was_shutdown;
 
 	if (chip == (void *)-1L)
 		return;
 
 	card = chip->card;
-	down_write(&chip->shutdown_rwsem);
-	was_shutdown = chip->shutdown;
-	chip->shutdown = 1;
-	up_write(&chip->shutdown_rwsem);
 
 	mutex_lock(&register_mutex);
-	if (!was_shutdown) {
+	if (atomic_inc_return(&chip->shutdown) == 1) {
 		struct snd_usb_stream *as;
 		struct snd_usb_endpoint *ep;
 		struct usb_mixer_interface *mixer;
 
+		/* wait until all pending tasks done;
+		 * they are protected by snd_usb_lock_shutdown()
+		 */
+		wait_event(chip->shutdown_wait,
+			   !atomic_read(&chip->usage_count));
 		snd_card_disconnect(card);
 		/* release the pcm resources */
 		list_for_each_entry(as, &chip->pcm_list, list) {
@@ -631,28 +633,56 @@ static void usb_audio_disconnect(struct usb_interface *intf)
 	}
 }
 
-#ifdef CONFIG_PM
-
-int snd_usb_autoresume(struct snd_usb_audio *chip)
+/* lock the shutdown (disconnect) task and autoresume */
+int snd_usb_lock_shutdown(struct snd_usb_audio *chip)
 {
-	int err = -ENODEV;
+	int err;
 
-	down_read(&chip->shutdown_rwsem);
-	if (chip->probing || chip->in_pm)
-		err = 0;
-	else if (!chip->shutdown)
-		err = usb_autopm_get_interface(chip->pm_intf);
-	up_read(&chip->shutdown_rwsem);
+	atomic_inc(&chip->usage_count);
+	if (atomic_read(&chip->shutdown)) {
+		err = -EIO;
+		goto error;
+	}
+	err = snd_usb_autoresume(chip);
+	if (err < 0)
+		goto error;
+	return 0;
 
+ error:
+	if (atomic_dec_and_test(&chip->usage_count))
+		wake_up(&chip->shutdown_wait);
 	return err;
 }
 
+/* autosuspend and unlock the shutdown */
+void snd_usb_unlock_shutdown(struct snd_usb_audio *chip)
+{
+	snd_usb_autosuspend(chip);
+	if (atomic_dec_and_test(&chip->usage_count))
+		wake_up(&chip->shutdown_wait);
+}
+
+#ifdef CONFIG_PM
+
+int snd_usb_autoresume(struct snd_usb_audio *chip)
+{
+	if (atomic_read(&chip->shutdown))
+		return -EIO;
+	if (chip->probing)
+		return 0;
+	if (atomic_inc_return(&chip->active) == 1)
+		return usb_autopm_get_interface(chip->pm_intf);
+	return 0;
+}
+
 void snd_usb_autosuspend(struct snd_usb_audio *chip)
 {
-	down_read(&chip->shutdown_rwsem);
-	if (!chip->shutdown && !chip->probing && !chip->in_pm)
+	if (chip->probing)
+		return;
+	if (atomic_read(&chip->shutdown))
+		return;
+	if (atomic_dec_and_test(&chip->active))
 		usb_autopm_put_interface(chip->pm_intf);
-	up_read(&chip->shutdown_rwsem);
 }
 
 static int usb_audio_suspend(struct usb_interface *intf, pm_message_t message)
@@ -705,7 +735,7 @@ static int __usb_audio_resume(struct usb_interface *intf, bool reset_resume)
 	if (--chip->num_suspended_intf)
 		return 0;
 
-	chip->in_pm = 1;
+	atomic_inc(&chip->active); /* avoid autopm */
 	/*
 	 * ALSA leaves material resumption to user space
 	 * we just notify and restart the mixers
@@ -725,7 +755,7 @@ static int __usb_audio_resume(struct usb_interface *intf, bool reset_resume)
 	chip->autosuspended = 0;
 
 err_out:
-	chip->in_pm = 0;
+	atomic_dec(&chip->active); /* allow autopm after this point */
 	return err;
 }