[media] em28xx: Fix em28xx deplock

When em28xx extensions are loaded/removed, there are two locks:

a single static em28xx_devlist_mutex that registers each extension
and the struct em28xx dev->lock.

When extensions are registered, em28xx_devlist_mutex is taken first,
and then dev->lock.

Be sure that, when extensions are being removed, the same order
will be used.

Reviewed-by: Frank Schäfer <fschaefer.oss@googlemail.com>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>

drivers/media/usb/em28xx/em28xx-cards.c

@@ -3485,9 +3485,7 @@ static void em28xx_usb_disconnect(struct usb_interface *interface)
 	dev->disconnected = 1;
 
 	if (dev->is_audio_only) {
-		mutex_lock(&dev->lock);
 		em28xx_close_extension(dev);
-		mutex_unlock(&dev->lock);
 		return;
 	}
 
@@ -3506,10 +3504,13 @@ static void em28xx_usb_disconnect(struct usb_interface *interface)
 		em28xx_uninit_usb_xfer(dev, EM28XX_ANALOG_MODE);
 		em28xx_uninit_usb_xfer(dev, EM28XX_DIGITAL_MODE);
 	}
+	mutex_unlock(&dev->lock);
 
 	em28xx_close_extension(dev);
+
 	/* NOTE: must be called BEFORE the resources are released */
 
+	mutex_lock(&dev->lock);
 	if (!dev->users)
 		em28xx_release_resources(dev);
 

drivers/media/usb/em28xx/em28xx-core.c

@@ -1094,10 +1094,12 @@ void em28xx_close_extension(struct em28xx *dev)
 	const struct em28xx_ops *ops = NULL;
 
 	mutex_lock(&em28xx_devlist_mutex);
+	mutex_lock(&dev->lock);
 	list_for_each_entry(ops, &em28xx_extension_devlist, next) {
 		if (ops->fini)
 			ops->fini(dev);
 	}
+	mutex_unlock(&dev->lock);
 	list_del(&dev->devlist);
 	mutex_unlock(&em28xx_devlist_mutex);
 }