lguest: do not statically allocate root device

index b02f6bc..40fa973 100644
@@ -321,10 +321,42 @@ static struct virtio_config_ops lguest_config_ops = {
 
 /* The root device for the lguest virtio devices.  This makes them appear as
  * /sys/devices/lguest/0,1,2 not /sys/devices/0,1,2. */
-static struct device lguest_root = {
-	.parent = NULL,
-	.bus_id = "lguest",
-};
+static struct device *lguest_root;
+
+static void lguest_release_root(struct device *root)
+{
+	kfree(root);
+}
+
+static int lguest_init_root(void)
+{
+	struct device *root;
+	int err = -ENOMEM;
+
+	root = kzalloc(sizeof(struct device), GFP_KERNEL);
+	if (root == NULL)
+		goto out;
+
+	err = dev_set_name(root, "lguest");
+	if (err)
+		goto free_root;
+
+	err = device_register(root);
+	if (err)
+		goto free_root;
+
+	root->parent  = NULL;
+	root->release = lguest_release_root;
+
+	lguest_root = root;
+
+	return 0;
+
+free_root:
+	kfree(root);
+out:
+	return err;
+}
 
 /*D:120 This is the core of the lguest bus: actually adding a new device.
  * It's a separate function because it's neater that way, and because an

@@ -351,7 +383,7 @@ static void add_lguest_device(struct lguest_device_desc *d,
 	}
 
 	/* This devices' parent is the lguest/ dir. */
-	ldev->vdev.dev.parent = &lguest_root;
+	ldev->vdev.dev.parent = lguest_root;
 	/* We have a unique device index thanks to the dev_index counter. */
 	ldev->vdev.id.device = d->type;
 	/* We have a simple set of routines for querying the device's

@@ -407,7 +439,7 @@ static int __init lguest_devices_init(void)
 	if (strcmp(pv_info.name, "lguest") != 0)
 		return 0;
 
-	if (device_register(&lguest_root) != 0)
+	if (lguest_init_root() != 0)
 		panic("Could not register lguest root");
 
 	/* Devices are in a single page above top of "normal" mem */

index 40fa973..3a1440a 100644
@@ -272,7 +272,7 @@ static struct virtqueue *lg_find_vq(struct virtio_device *vdev,
 	 * the interrupt as a source of randomness: it'd be nice to have that
 	 * back.. */
 	err = request_irq(lvq->config.irq, vring_interrupt, IRQF_SHARED,
-			  vdev->dev.bus_id, vq);
+			  dev_name(&vdev->dev), vq);
 	if (err)
 		goto destroy_vring;