4 files changed, 270 insertions, 289 deletions

diff --git a/drivers/net/xen-netback/hash.c b/drivers/net/xen-netback/hash.c
index 10d580c3dea3..6b7532f7c936 100644
--- a/drivers/net/xen-netback/hash.c
+++ b/drivers/net/xen-netback/hash.c
@@ -51,7 +51,8 @@ static void xenvif_add_hash(struct xenvif *vif, const u8 *tag,
 
 	found = false;
 	oldest = NULL;
-	list_for_each_entry_rcu(entry, &vif->hash.cache.list, link) {
+	list_for_each_entry_rcu(entry, &vif->hash.cache.list, link,
+				lockdep_is_held(&vif->hash.cache.lock)) {
 		/* Make sure we don't add duplicate entries */
 		if (entry->len == len &&
 		    memcmp(entry->tag, tag, len) == 0)
@@ -102,7 +103,8 @@ static void xenvif_flush_hash(struct xenvif *vif)
 
 	spin_lock_irqsave(&vif->hash.cache.lock, flags);
 
-	list_for_each_entry_rcu(entry, &vif->hash.cache.list, link) {
+	list_for_each_entry_rcu(entry, &vif->hash.cache.list, link,
+				lockdep_is_held(&vif->hash.cache.lock)) {
 		list_del_rcu(&entry->link);
 		vif->hash.cache.count--;
 		kfree_rcu(entry, rcu);
diff --git a/drivers/net/xen-netback/interface.c b/drivers/net/xen-netback/interface.c
index 240f762b3749..0c8a02a1ead7 100644
--- a/drivers/net/xen-netback/interface.c
+++ b/drivers/net/xen-netback/interface.c
@@ -585,6 +585,7 @@ int xenvif_connect_ctrl(struct xenvif *vif, grant_ref_t ring_ref,
 	struct net_device *dev = vif->dev;
 	void *addr;
 	struct xen_netif_ctrl_sring *shared;
+	RING_IDX rsp_prod, req_prod;
 	int err;
 
 	err = xenbus_map_ring_valloc(xenvif_to_xenbus_device(vif),
@@ -593,7 +594,14 @@ int xenvif_connect_ctrl(struct xenvif *vif, grant_ref_t ring_ref,
 		goto err;
 
 	shared = (struct xen_netif_ctrl_sring *)addr;
-	BACK_RING_INIT(&vif->ctrl, shared, XEN_PAGE_SIZE);
+	rsp_prod = READ_ONCE(shared->rsp_prod);
+	req_prod = READ_ONCE(shared->req_prod);
+
+	BACK_RING_ATTACH(&vif->ctrl, shared, rsp_prod, XEN_PAGE_SIZE);
+
+	err = -EIO;
+	if (req_prod - rsp_prod > RING_SIZE(&vif->ctrl))
+		goto err_unmap;
 
 	err = bind_interdomain_evtchn_to_irq(vif->domid, evtchn);
 	if (err < 0)
@@ -626,6 +634,38 @@ err:
 	return err;
 }
 
+static void xenvif_disconnect_queue(struct xenvif_queue *queue)
+{
+	if (queue->task) {
+		kthread_stop(queue->task);
+		queue->task = NULL;
+	}
+
+	if (queue->dealloc_task) {
+		kthread_stop(queue->dealloc_task);
+		queue->dealloc_task = NULL;
+	}
+
+	if (queue->napi.poll) {
+		netif_napi_del(&queue->napi);
+		queue->napi.poll = NULL;
+	}
+
+	if (queue->tx_irq) {
+		unbind_from_irqhandler(queue->tx_irq, queue);
+		if (queue->tx_irq == queue->rx_irq)
+			queue->rx_irq = 0;
+		queue->tx_irq = 0;
+	}
+
+	if (queue->rx_irq) {
+		unbind_from_irqhandler(queue->rx_irq, queue);
+		queue->rx_irq = 0;
+	}
+
+	xenvif_unmap_frontend_data_rings(queue);
+}
+
 int xenvif_connect_data(struct xenvif_queue *queue,
 			unsigned long tx_ring_ref,
 			unsigned long rx_ring_ref,
@@ -651,13 +691,27 @@ int xenvif_connect_data(struct xenvif_queue *queue,
 	netif_napi_add(queue->vif->dev, &queue->napi, xenvif_poll,
 			XENVIF_NAPI_WEIGHT);
 
+	queue->stalled = true;
+
+	task = kthread_run(xenvif_kthread_guest_rx, queue,
+			   "%s-guest-rx", queue->name);
+	if (IS_ERR(task))
+		goto kthread_err;
+	queue->task = task;
+
+	task = kthread_run(xenvif_dealloc_kthread, queue,
+			   "%s-dealloc", queue->name);
+	if (IS_ERR(task))
+		goto kthread_err;
+	queue->dealloc_task = task;
+
 	if (tx_evtchn == rx_evtchn) {
 		/* feature-split-event-channels == 0 */
 		err = bind_interdomain_evtchn_to_irqhandler(
 			queue->vif->domid, tx_evtchn, xenvif_interrupt, 0,
 			queue->name, queue);
 		if (err < 0)
-			goto err_unmap;
+			goto err;
 		queue->tx_irq = queue->rx_irq = err;
 		disable_irq(queue->tx_irq);
 	} else {
@@ -668,7 +722,7 @@ int xenvif_connect_data(struct xenvif_queue *queue,
 			queue->vif->domid, tx_evtchn, xenvif_tx_interrupt, 0,
 			queue->tx_irq_name, queue);
 		if (err < 0)
-			goto err_unmap;
+			goto err;
 		queue->tx_irq = err;
 		disable_irq(queue->tx_irq);
 
@@ -678,48 +732,18 @@ int xenvif_connect_data(struct xenvif_queue *queue,
 			queue->vif->domid, rx_evtchn, xenvif_rx_interrupt, 0,
 			queue->rx_irq_name, queue);
 		if (err < 0)
-			goto err_tx_unbind;
+			goto err;
 		queue->rx_irq = err;
 		disable_irq(queue->rx_irq);
 	}
 
-	queue->stalled = true;
-
-	task = kthread_create(xenvif_kthread_guest_rx,
-			      (void *)queue, "%s-guest-rx", queue->name);
-	if (IS_ERR(task)) {
-		pr_warn("Could not allocate kthread for %s\n", queue->name);
-		err = PTR_ERR(task);
-		goto err_rx_unbind;
-	}
-	queue->task = task;
-	get_task_struct(task);
-
-	task = kthread_create(xenvif_dealloc_kthread,
-			      (void *)queue, "%s-dealloc", queue->name);
-	if (IS_ERR(task)) {
-		pr_warn("Could not allocate kthread for %s\n", queue->name);
-		err = PTR_ERR(task);
-		goto err_rx_unbind;
-	}
-	queue->dealloc_task = task;
-
-	wake_up_process(queue->task);
-	wake_up_process(queue->dealloc_task);
-
 	return 0;
 
-err_rx_unbind:
-	unbind_from_irqhandler(queue->rx_irq, queue);
-	queue->rx_irq = 0;
-err_tx_unbind:
-	unbind_from_irqhandler(queue->tx_irq, queue);
-	queue->tx_irq = 0;
-err_unmap:
-	xenvif_unmap_frontend_data_rings(queue);
-	netif_napi_del(&queue->napi);
+kthread_err:
+	pr_warn("Could not allocate kthread for %s\n", queue->name);
+	err = PTR_ERR(task);
 err:
-	module_put(THIS_MODULE);
+	xenvif_disconnect_queue(queue);
 	return err;
 }
 
@@ -747,30 +771,7 @@ void xenvif_disconnect_data(struct xenvif *vif)
 	for (queue_index = 0; queue_index < num_queues; ++queue_index) {
 		queue = &vif->queues[queue_index];
 
-		netif_napi_del(&queue->napi);
-
-		if (queue->task) {
-			kthread_stop(queue->task);
-			put_task_struct(queue->task);
-			queue->task = NULL;
-		}
-
-		if (queue->dealloc_task) {
-			kthread_stop(queue->dealloc_task);
-			queue->dealloc_task = NULL;
-		}
-
-		if (queue->tx_irq) {
-			if (queue->tx_irq == queue->rx_irq)
-				unbind_from_irqhandler(queue->tx_irq, queue);
-			else {
-				unbind_from_irqhandler(queue->tx_irq, queue);
-				unbind_from_irqhandler(queue->rx_irq, queue);
-			}
-			queue->tx_irq = 0;
-		}
-
-		xenvif_unmap_frontend_data_rings(queue);
+		xenvif_disconnect_queue(queue);
 	}
 
 	xenvif_mcast_addr_list_free(vif);
diff --git a/drivers/net/xen-netback/netback.c b/drivers/net/xen-netback/netback.c
index c9262ffeefe4..315dfc6ea297 100644
--- a/drivers/net/xen-netback/netback.c
+++ b/drivers/net/xen-netback/netback.c
@@ -136,12 +136,12 @@ static inline struct xenvif_queue *ubuf_to_queue(const struct ubuf_info *ubuf)
 
 static u16 frag_get_pending_idx(skb_frag_t *frag)
 {
-	return (u16)frag->page_offset;
+	return (u16)skb_frag_off(frag);
 }
 
 static void frag_set_pending_idx(skb_frag_t *frag, u16 pending_idx)
 {
-	frag->page_offset = pending_idx;
+	skb_frag_off_set(frag, pending_idx);
 }
 
 static inline pending_ring_idx_t pending_index(unsigned i)
@@ -1057,7 +1057,7 @@ static int xenvif_handle_frag_list(struct xenvif_queue *queue, struct sk_buff *s
 			int j;
 			skb->truesize += skb->data_len;
 			for (j = 0; j < i; j++)
-				put_page(frags[j].page.p);
+				put_page(skb_frag_page(&frags[j]));
 			return -ENOMEM;
 		}
 
@@ -1069,8 +1069,8 @@ static int xenvif_handle_frag_list(struct xenvif_queue *queue, struct sk_buff *s
 			BUG();
 
 		offset += len;
-		frags[i].page.p = page;
-		frags[i].page_offset = 0;
+		__skb_frag_set_page(&frags[i], page);
+		skb_frag_off_set(&frags[i], 0);
 		skb_frag_size_set(&frags[i], len);
 	}
 
@@ -1453,7 +1453,7 @@ int xenvif_map_frontend_data_rings(struct xenvif_queue *queue,
 	void *addr;
 	struct xen_netif_tx_sring *txs;
 	struct xen_netif_rx_sring *rxs;
-
+	RING_IDX rsp_prod, req_prod;
 	int err = -ENOMEM;
 
 	err = xenbus_map_ring_valloc(xenvif_to_xenbus_device(queue->vif),
@@ -1462,7 +1462,14 @@ int xenvif_map_frontend_data_rings(struct xenvif_queue *queue,
 		goto err;
 
 	txs = (struct xen_netif_tx_sring *)addr;
-	BACK_RING_INIT(&queue->tx, txs, XEN_PAGE_SIZE);
+	rsp_prod = READ_ONCE(txs->rsp_prod);
+	req_prod = READ_ONCE(txs->req_prod);
+
+	BACK_RING_ATTACH(&queue->tx, txs, rsp_prod, XEN_PAGE_SIZE);
+
+	err = -EIO;
+	if (req_prod - rsp_prod > RING_SIZE(&queue->tx))
+		goto err;
 
 	err = xenbus_map_ring_valloc(xenvif_to_xenbus_device(queue->vif),
 				     &rx_ring_ref, 1, &addr);
@@ -1470,7 +1477,14 @@ int xenvif_map_frontend_data_rings(struct xenvif_queue *queue,
 		goto err;
 
 	rxs = (struct xen_netif_rx_sring *)addr;
-	BACK_RING_INIT(&queue->rx, rxs, XEN_PAGE_SIZE);
+	rsp_prod = READ_ONCE(rxs->rsp_prod);
+	req_prod = READ_ONCE(rxs->req_prod);
+
+	BACK_RING_ATTACH(&queue->rx, rxs, rsp_prod, XEN_PAGE_SIZE);
+
+	err = -EIO;
+	if (req_prod - rsp_prod > RING_SIZE(&queue->rx))
+		goto err;
 
 	return 0;
 
@@ -1655,9 +1669,6 @@ static int __init netback_init(void)
 
 #ifdef CONFIG_DEBUG_FS
 	xen_netback_dbg_root = debugfs_create_dir("xen-netback", NULL);
-	if (IS_ERR_OR_NULL(xen_netback_dbg_root))
-		pr_warn("Init of debugfs returned %ld!\n",
-			PTR_ERR(xen_netback_dbg_root));
 #endif /* CONFIG_DEBUG_FS */
 
 	return 0;
diff --git a/drivers/net/xen-netback/xenbus.c b/drivers/net/xen-netback/xenbus.c
index 41034264bd34..286054b60d47 100644
--- a/drivers/net/xen-netback/xenbus.c
+++ b/drivers/net/xen-netback/xenbus.c
@@ -170,234 +170,31 @@ DEFINE_SHOW_ATTRIBUTE(xenvif_ctrl);
 
 static void xenvif_debugfs_addif(struct xenvif *vif)
 {
-	struct dentry *pfile;
 	int i;
 
-	if (IS_ERR_OR_NULL(xen_netback_dbg_root))
-		return;
-
 	vif->xenvif_dbg_root = debugfs_create_dir(vif->dev->name,
 						  xen_netback_dbg_root);
-	if (!IS_ERR_OR_NULL(vif->xenvif_dbg_root)) {
-		for (i = 0; i < vif->num_queues; ++i) {
-			char filename[sizeof("io_ring_q") + 4];
-
-			snprintf(filename, sizeof(filename), "io_ring_q%d", i);
-			pfile = debugfs_create_file(filename,
-						    0600,
-						    vif->xenvif_dbg_root,
-						    &vif->queues[i],
-						    &xenvif_dbg_io_ring_ops_fops);
-			if (IS_ERR_OR_NULL(pfile))
-				pr_warn("Creation of io_ring file returned %ld!\n",
-					PTR_ERR(pfile));
-		}
+	for (i = 0; i < vif->num_queues; ++i) {
+		char filename[sizeof("io_ring_q") + 4];
 
-		if (vif->ctrl_irq) {
-			pfile = debugfs_create_file("ctrl",
-						    0400,
-						    vif->xenvif_dbg_root,
-						    vif,
-						    &xenvif_ctrl_fops);
-			if (IS_ERR_OR_NULL(pfile))
-				pr_warn("Creation of ctrl file returned %ld!\n",
-					PTR_ERR(pfile));
-		}
-	} else
-		netdev_warn(vif->dev,
-			    "Creation of vif debugfs dir returned %ld!\n",
-			    PTR_ERR(vif->xenvif_dbg_root));
+		snprintf(filename, sizeof(filename), "io_ring_q%d", i);
+		debugfs_create_file(filename, 0600, vif->xenvif_dbg_root,
+				    &vif->queues[i],
+				    &xenvif_dbg_io_ring_ops_fops);
+	}
+
+	if (vif->ctrl_irq)
+		debugfs_create_file("ctrl", 0400, vif->xenvif_dbg_root, vif,
+				    &xenvif_ctrl_fops);
 }
 
 static void xenvif_debugfs_delif(struct xenvif *vif)
 {
-	if (IS_ERR_OR_NULL(xen_netback_dbg_root))
-		return;
-
 	debugfs_remove_recursive(vif->xenvif_dbg_root);
 	vif->xenvif_dbg_root = NULL;
 }
 #endif /* CONFIG_DEBUG_FS */
 
-static int netback_remove(struct xenbus_device *dev)
-{
-	struct backend_info *be = dev_get_drvdata(&dev->dev);
-
-	set_backend_state(be, XenbusStateClosed);
-
-	unregister_hotplug_status_watch(be);
-	if (be->vif) {
-		kobject_uevent(&dev->dev.kobj, KOBJ_OFFLINE);
-		xen_unregister_watchers(be->vif);
-		xenbus_rm(XBT_NIL, dev->nodename, "hotplug-status");
-		xenvif_free(be->vif);
-		be->vif = NULL;
-	}
-	kfree(be->hotplug_script);
-	kfree(be);
-	dev_set_drvdata(&dev->dev, NULL);
-	return 0;
-}
-
-
-/**
- * Entry point to this code when a new device is created.  Allocate the basic
- * structures and switch to InitWait.
- */
-static int netback_probe(struct xenbus_device *dev,
-			 const struct xenbus_device_id *id)
-{
-	const char *message;
-	struct xenbus_transaction xbt;
-	int err;
-	int sg;
-	const char *script;
-	struct backend_info *be = kzalloc(sizeof(struct backend_info),
-					  GFP_KERNEL);
-	if (!be) {
-		xenbus_dev_fatal(dev, -ENOMEM,
-				 "allocating backend structure");
-		return -ENOMEM;
-	}
-
-	be->dev = dev;
-	dev_set_drvdata(&dev->dev, be);
-
-	be->state = XenbusStateInitialising;
-	err = xenbus_switch_state(dev, XenbusStateInitialising);
-	if (err)
-		goto fail;
-
-	sg = 1;
-
-	do {
-		err = xenbus_transaction_start(&xbt);
-		if (err) {
-			xenbus_dev_fatal(dev, err, "starting transaction");
-			goto fail;
-		}
-
-		err = xenbus_printf(xbt, dev->nodename, "feature-sg", "%d", sg);
-		if (err) {
-			message = "writing feature-sg";
-			goto abort_transaction;
-		}
-
-		err = xenbus_printf(xbt, dev->nodename, "feature-gso-tcpv4",
-				    "%d", sg);
-		if (err) {
-			message = "writing feature-gso-tcpv4";
-			goto abort_transaction;
-		}
-
-		err = xenbus_printf(xbt, dev->nodename, "feature-gso-tcpv6",
-				    "%d", sg);
-		if (err) {
-			message = "writing feature-gso-tcpv6";
-			goto abort_transaction;
-		}
-
-		/* We support partial checksum setup for IPv6 packets */
-		err = xenbus_printf(xbt, dev->nodename,
-				    "feature-ipv6-csum-offload",
-				    "%d", 1);
-		if (err) {
-			message = "writing feature-ipv6-csum-offload";
-			goto abort_transaction;
-		}
-
-		/* We support rx-copy path. */
-		err = xenbus_printf(xbt, dev->nodename,
-				    "feature-rx-copy", "%d", 1);
-		if (err) {
-			message = "writing feature-rx-copy";
-			goto abort_transaction;
-		}
-
-		/*
-		 * We don't support rx-flip path (except old guests who don't
-		 * grok this feature flag).
-		 */
-		err = xenbus_printf(xbt, dev->nodename,
-				    "feature-rx-flip", "%d", 0);
-		if (err) {
-			message = "writing feature-rx-flip";
-			goto abort_transaction;
-		}
-
-		/* We support dynamic multicast-control. */
-		err = xenbus_printf(xbt, dev->nodename,
-				    "feature-multicast-control", "%d", 1);
-		if (err) {
-			message = "writing feature-multicast-control";
-			goto abort_transaction;
-		}
-
-		err = xenbus_printf(xbt, dev->nodename,
-				    "feature-dynamic-multicast-control",
-				    "%d", 1);
-		if (err) {
-			message = "writing feature-dynamic-multicast-control";
-			goto abort_transaction;
-		}
-
-		err = xenbus_transaction_end(xbt, 0);
-	} while (err == -EAGAIN);
-
-	if (err) {
-		xenbus_dev_fatal(dev, err, "completing transaction");
-		goto fail;
-	}
-
-	/*
-	 * Split event channels support, this is optional so it is not
-	 * put inside the above loop.
-	 */
-	err = xenbus_printf(XBT_NIL, dev->nodename,
-			    "feature-split-event-channels",
-			    "%u", separate_tx_rx_irq);
-	if (err)
-		pr_debug("Error writing feature-split-event-channels\n");
-
-	/* Multi-queue support: This is an optional feature. */
-	err = xenbus_printf(XBT_NIL, dev->nodename,
-			    "multi-queue-max-queues", "%u", xenvif_max_queues);
-	if (err)
-		pr_debug("Error writing multi-queue-max-queues\n");
-
-	err = xenbus_printf(XBT_NIL, dev->nodename,
-			    "feature-ctrl-ring",
-			    "%u", true);
-	if (err)
-		pr_debug("Error writing feature-ctrl-ring\n");
-
-	script = xenbus_read(XBT_NIL, dev->nodename, "script", NULL);
-	if (IS_ERR(script)) {
-		err = PTR_ERR(script);
-		xenbus_dev_fatal(dev, err, "reading script");
-		goto fail;
-	}
-
-	be->hotplug_script = script;
-
-
-	/* This kicks hotplug scripts, so do it immediately. */
-	err = backend_create_xenvif(be);
-	if (err)
-		goto fail;
-
-	return 0;
-
-abort_transaction:
-	xenbus_transaction_end(xbt, 1);
-	xenbus_dev_fatal(dev, err, "%s", message);
-fail:
-	pr_debug("failed\n");
-	netback_remove(dev);
-	return err;
-}
-
-
 /*
  * Handle the creation of the hotplug script environment.  We add the script
  * and vif variables to the environment, for the benefit of the vif-* hotplug
@@ -851,6 +648,7 @@ static void hotplug_status_changed(struct xenbus_watch *watch,
 
 		/* Not interested in this watch anymore. */
 		unregister_hotplug_status_watch(be);
+		xenbus_rm(XBT_NIL, be->dev->nodename, "hotplug-status");
 	}
 	kfree(str);
 }
@@ -1152,6 +950,174 @@ static int read_xenbus_vif_flags(struct backend_info *be)
 	return 0;
 }
 
+static int netback_remove(struct xenbus_device *dev)
+{
+	struct backend_info *be = dev_get_drvdata(&dev->dev);
+
+	unregister_hotplug_status_watch(be);
+	if (be->vif) {
+		kobject_uevent(&dev->dev.kobj, KOBJ_OFFLINE);
+		backend_disconnect(be);
+		xenvif_free(be->vif);
+		be->vif = NULL;
+	}
+	kfree(be->hotplug_script);
+	kfree(be);
+	dev_set_drvdata(&dev->dev, NULL);
+	return 0;
+}
+
+/**
+ * Entry point to this code when a new device is created.  Allocate the basic
+ * structures and switch to InitWait.
+ */
+static int netback_probe(struct xenbus_device *dev,
+			 const struct xenbus_device_id *id)
+{
+	const char *message;
+	struct xenbus_transaction xbt;
+	int err;
+	int sg;
+	const char *script;
+	struct backend_info *be = kzalloc(sizeof(*be), GFP_KERNEL);
+
+	if (!be) {
+		xenbus_dev_fatal(dev, -ENOMEM,
+				 "allocating backend structure");
+		return -ENOMEM;
+	}
+
+	be->dev = dev;
+	dev_set_drvdata(&dev->dev, be);
+
+	sg = 1;
+
+	do {
+		err = xenbus_transaction_start(&xbt);
+		if (err) {
+			xenbus_dev_fatal(dev, err, "starting transaction");
+			goto fail;
+		}
+
+		err = xenbus_printf(xbt, dev->nodename, "feature-sg", "%d", sg);
+		if (err) {
+			message = "writing feature-sg";
+			goto abort_transaction;
+		}
+
+		err = xenbus_printf(xbt, dev->nodename, "feature-gso-tcpv4",
+				    "%d", sg);
+		if (err) {
+			message = "writing feature-gso-tcpv4";
+			goto abort_transaction;
+		}
+
+		err = xenbus_printf(xbt, dev->nodename, "feature-gso-tcpv6",
+				    "%d", sg);
+		if (err) {
+			message = "writing feature-gso-tcpv6";
+			goto abort_transaction;
+		}
+
+		/* We support partial checksum setup for IPv6 packets */
+		err = xenbus_printf(xbt, dev->nodename,
+				    "feature-ipv6-csum-offload",
+				    "%d", 1);
+		if (err) {
+			message = "writing feature-ipv6-csum-offload";
+			goto abort_transaction;
+		}
+
+		/* We support rx-copy path. */
+		err = xenbus_printf(xbt, dev->nodename,
+				    "feature-rx-copy", "%d", 1);
+		if (err) {
+			message = "writing feature-rx-copy";
+			goto abort_transaction;
+		}
+
+		/* We don't support rx-flip path (except old guests who
+		 * don't grok this feature flag).
+		 */
+		err = xenbus_printf(xbt, dev->nodename,
+				    "feature-rx-flip", "%d", 0);
+		if (err) {
+			message = "writing feature-rx-flip";
+			goto abort_transaction;
+		}
+
+		/* We support dynamic multicast-control. */
+		err = xenbus_printf(xbt, dev->nodename,
+				    "feature-multicast-control", "%d", 1);
+		if (err) {
+			message = "writing feature-multicast-control";
+			goto abort_transaction;
+		}
+
+		err = xenbus_printf(xbt, dev->nodename,
+				    "feature-dynamic-multicast-control",
+				    "%d", 1);
+		if (err) {
+			message = "writing feature-dynamic-multicast-control";
+			goto abort_transaction;
+		}
+
+		err = xenbus_transaction_end(xbt, 0);
+	} while (err == -EAGAIN);
+
+	if (err) {
+		xenbus_dev_fatal(dev, err, "completing transaction");
+		goto fail;
+	}
+
+	/* Split event channels support, this is optional so it is not
+	 * put inside the above loop.
+	 */
+	err = xenbus_printf(XBT_NIL, dev->nodename,
+			    "feature-split-event-channels",
+			    "%u", separate_tx_rx_irq);
+	if (err)
+		pr_debug("Error writing feature-split-event-channels\n");
+
+	/* Multi-queue support: This is an optional feature. */
+	err = xenbus_printf(XBT_NIL, dev->nodename,
+			    "multi-queue-max-queues", "%u", xenvif_max_queues);
+	if (err)
+		pr_debug("Error writing multi-queue-max-queues\n");
+
+	err = xenbus_printf(XBT_NIL, dev->nodename,
+			    "feature-ctrl-ring",
+			    "%u", true);
+	if (err)
+		pr_debug("Error writing feature-ctrl-ring\n");
+
+	backend_switch_state(be, XenbusStateInitWait);
+
+	script = xenbus_read(XBT_NIL, dev->nodename, "script", NULL);
+	if (IS_ERR(script)) {
+		err = PTR_ERR(script);
+		xenbus_dev_fatal(dev, err, "reading script");
+		goto fail;
+	}
+
+	be->hotplug_script = script;
+
+	/* This kicks hotplug scripts, so do it immediately. */
+	err = backend_create_xenvif(be);
+	if (err)
+		goto fail;
+
+	return 0;
+
+abort_transaction:
+	xenbus_transaction_end(xbt, 1);
+	xenbus_dev_fatal(dev, err, "%s", message);
+fail:
+	pr_debug("failed\n");
+	netback_remove(dev);
+	return err;
+}
+
 static const struct xenbus_device_id netback_ids[] = {
 	{ "vif" },
 	{ "" }
@@ -1163,6 +1129,7 @@ static struct xenbus_driver netback_driver = {
 	.remove = netback_remove,
 	.uevent = netback_uevent,
 	.otherend_changed = frontend_changed,
+	.allow_rebind = true,
 };
 
 int xenvif_xenbus_init(void)