[media] em28xx: fix deadlock when unplugging and replugging a DVB adapter

This fixes the deadlock that occurs with either multiple PCTV 290e adapters or when a single PCTV 290e adapter is replugged.

For DVB devices, the device lock must now *not* be held when adding/removing either a device or an extension to the respective lists. (Because em28xx_init_dvb() will want to take the lock instead).

Conversely, for Audio-Only devices, the device lock *must* be held when adding/removing either a device or an extension to the respective lists.
Signed-off-by: NChris Rankin <rankincj@yahoo.com>
Signed-off-by: NMauro Carvalho Chehab <mchehab@redhat.com>

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

@@ -3005,7 +3005,9 @@ static int em28xx_init_dev(struct em28xx **devhandle, struct usb_device *udev,
 		goto fail;
 	}
 
+	mutex_unlock(&dev->lock);
 	em28xx_init_extension(dev);
+	mutex_lock(&dev->lock);
 
 	/* Save some power by putting tuner to sleep */
 	v4l2_device_call_all(&dev->v4l2_dev, 0, core, s_power, 0);
@@ -3301,10 +3303,10 @@ static void em28xx_usb_disconnect(struct usb_interface *interface)
 		em28xx_release_resources(dev);
 	}
 
-	em28xx_close_extension(dev);
-
 	mutex_unlock(&dev->lock);
 
+	em28xx_close_extension(dev);
+
 	if (!dev->users) {
 		kfree(dev->alt_max_pkt_size);
 		kfree(dev);