EM28xx - fix deadlock when unplugging and replugging a DVB adapter

Mauro,

Pending the complete rethink about how USB devices manage their resources, I am resubmitting my fix for the PCTV 290e deadlock that occurs with either multiple adapters or when an 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.

Cheers,
Chris

@@ -3005,9 +3005,7 @@
 		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);

@@ -3303,10 +3301,10 @@
 		em28xx_release_resources(dev);
 	}
 
-	mutex_unlock(&dev->lock);
-
 	em28xx_close_extension(dev);
 
+	mutex_unlock(&dev->lock);
+
 	if (!dev->users) {
 		kfree(dev->alt_max_pkt_size);
 		kfree(dev);