Initial import

1 files changed, 2049 insertions, 0 deletions

diff --git a/drivers/net/xen-netback/netback.c b/drivers/net/xen-netback/netback.c
new file mode 100644
index 000000000..0d2594395
--- /dev/null
+++ b/drivers/net/xen-netback/netback.c
@@ -0,0 +1,2049 @@
+/*
+ * Back-end of the driver for virtual network devices. This portion of the
+ * driver exports a 'unified' network-device interface that can be accessed
+ * by any operating system that implements a compatible front end. A
+ * reference front-end implementation can be found in:
+ *  drivers/net/xen-netfront.c
+ *
+ * Copyright (c) 2002-2005, K A Fraser
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License version 2
+ * as published by the Free Software Foundation; or, when distributed
+ * separately from the Linux kernel or incorporated into other
+ * software packages, subject to the following license:
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this source file (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use, copy, modify,
+ * merge, publish, distribute, sublicense, and/or sell copies of the Software,
+ * and to permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ */
+
+#include "common.h"
+
+#include <linux/kthread.h>
+#include <linux/if_vlan.h>
+#include <linux/udp.h>
+#include <linux/highmem.h>
+
+#include <net/tcp.h>
+
+#include <xen/xen.h>
+#include <xen/events.h>
+#include <xen/interface/memory.h>
+
+#include <asm/xen/hypercall.h>
+#include <asm/xen/page.h>
+
+/* Provide an option to disable split event channels at load time as
+ * event channels are limited resource. Split event channels are
+ * enabled by default.
+ */
+bool separate_tx_rx_irq = 1;
+module_param(separate_tx_rx_irq, bool, 0644);
+
+/* The time that packets can stay on the guest Rx internal queue
+ * before they are dropped.
+ */
+unsigned int rx_drain_timeout_msecs = 10000;
+module_param(rx_drain_timeout_msecs, uint, 0444);
+
+/* The length of time before the frontend is considered unresponsive
+ * because it isn't providing Rx slots.
+ */
+unsigned int rx_stall_timeout_msecs = 60000;
+module_param(rx_stall_timeout_msecs, uint, 0444);
+
+unsigned int xenvif_max_queues;
+module_param_named(max_queues, xenvif_max_queues, uint, 0644);
+MODULE_PARM_DESC(max_queues,
+		 "Maximum number of queues per virtual interface");
+
+/*
+ * This is the maximum slots a skb can have. If a guest sends a skb
+ * which exceeds this limit it is considered malicious.
+ */
+#define FATAL_SKB_SLOTS_DEFAULT 20
+static unsigned int fatal_skb_slots = FATAL_SKB_SLOTS_DEFAULT;
+module_param(fatal_skb_slots, uint, 0444);
+
+/* The amount to copy out of the first guest Tx slot into the skb's
+ * linear area.  If the first slot has more data, it will be mapped
+ * and put into the first frag.
+ *
+ * This is sized to avoid pulling headers from the frags for most
+ * TCP/IP packets.
+ */
+#define XEN_NETBACK_TX_COPY_LEN 128
+
+
+static void xenvif_idx_release(struct xenvif_queue *queue, u16 pending_idx,
+			       u8 status);
+
+static void make_tx_response(struct xenvif_queue *queue,
+			     struct xen_netif_tx_request *txp,
+			     s8       st);
+static void push_tx_responses(struct xenvif_queue *queue);
+
+static inline int tx_work_todo(struct xenvif_queue *queue);
+
+static struct xen_netif_rx_response *make_rx_response(struct xenvif_queue *queue,
+					     u16      id,
+					     s8       st,
+					     u16      offset,
+					     u16      size,
+					     u16      flags);
+
+static inline unsigned long idx_to_pfn(struct xenvif_queue *queue,
+				       u16 idx)
+{
+	return page_to_pfn(queue->mmap_pages[idx]);
+}
+
+static inline unsigned long idx_to_kaddr(struct xenvif_queue *queue,
+					 u16 idx)
+{
+	return (unsigned long)pfn_to_kaddr(idx_to_pfn(queue, idx));
+}
+
+#define callback_param(vif, pending_idx) \
+	(vif->pending_tx_info[pending_idx].callback_struct)
+
+/* Find the containing VIF's structure from a pointer in pending_tx_info array
+ */
+static inline struct xenvif_queue *ubuf_to_queue(const struct ubuf_info *ubuf)
+{
+	u16 pending_idx = ubuf->desc;
+	struct pending_tx_info *temp =
+		container_of(ubuf, struct pending_tx_info, callback_struct);
+	return container_of(temp - pending_idx,
+			    struct xenvif_queue,
+			    pending_tx_info[0]);
+}
+
+static u16 frag_get_pending_idx(skb_frag_t *frag)
+{
+	return (u16)frag->page_offset;
+}
+
+static void frag_set_pending_idx(skb_frag_t *frag, u16 pending_idx)
+{
+	frag->page_offset = pending_idx;
+}
+
+static inline pending_ring_idx_t pending_index(unsigned i)
+{
+	return i & (MAX_PENDING_REQS-1);
+}
+
+bool xenvif_rx_ring_slots_available(struct xenvif_queue *queue, int needed)
+{
+	RING_IDX prod, cons;
+
+	do {
+		prod = queue->rx.sring->req_prod;
+		cons = queue->rx.req_cons;
+
+		if (prod - cons >= needed)
+			return true;
+
+		queue->rx.sring->req_event = prod + 1;
+
+		/* Make sure event is visible before we check prod
+		 * again.
+		 */
+		mb();
+	} while (queue->rx.sring->req_prod != prod);
+
+	return false;
+}
+
+void xenvif_rx_queue_tail(struct xenvif_queue *queue, struct sk_buff *skb)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&queue->rx_queue.lock, flags);
+
+	__skb_queue_tail(&queue->rx_queue, skb);
+
+	queue->rx_queue_len += skb->len;
+	if (queue->rx_queue_len > queue->rx_queue_max)
+		netif_tx_stop_queue(netdev_get_tx_queue(queue->vif->dev, queue->id));
+
+	spin_unlock_irqrestore(&queue->rx_queue.lock, flags);
+}
+
+static struct sk_buff *xenvif_rx_dequeue(struct xenvif_queue *queue)
+{
+	struct sk_buff *skb;
+
+	spin_lock_irq(&queue->rx_queue.lock);
+
+	skb = __skb_dequeue(&queue->rx_queue);
+	if (skb)
+		queue->rx_queue_len -= skb->len;
+
+	spin_unlock_irq(&queue->rx_queue.lock);
+
+	return skb;
+}
+
+static void xenvif_rx_queue_maybe_wake(struct xenvif_queue *queue)
+{
+	spin_lock_irq(&queue->rx_queue.lock);
+
+	if (queue->rx_queue_len < queue->rx_queue_max)
+		netif_tx_wake_queue(netdev_get_tx_queue(queue->vif->dev, queue->id));
+
+	spin_unlock_irq(&queue->rx_queue.lock);
+}
+
+
+static void xenvif_rx_queue_purge(struct xenvif_queue *queue)
+{
+	struct sk_buff *skb;
+	while ((skb = xenvif_rx_dequeue(queue)) != NULL)
+		kfree_skb(skb);
+}
+
+static void xenvif_rx_queue_drop_expired(struct xenvif_queue *queue)
+{
+	struct sk_buff *skb;
+
+	for(;;) {
+		skb = skb_peek(&queue->rx_queue);
+		if (!skb)
+			break;
+		if (time_before(jiffies, XENVIF_RX_CB(skb)->expires))
+			break;
+		xenvif_rx_dequeue(queue);
+		kfree_skb(skb);
+	}
+}
+
+struct netrx_pending_operations {
+	unsigned copy_prod, copy_cons;
+	unsigned meta_prod, meta_cons;
+	struct gnttab_copy *copy;
+	struct xenvif_rx_meta *meta;
+	int copy_off;
+	grant_ref_t copy_gref;
+};
+
+static struct xenvif_rx_meta *get_next_rx_buffer(struct xenvif_queue *queue,
+						 struct netrx_pending_operations *npo)
+{
+	struct xenvif_rx_meta *meta;
+	struct xen_netif_rx_request *req;
+
+	req = RING_GET_REQUEST(&queue->rx, queue->rx.req_cons++);
+
+	meta = npo->meta + npo->meta_prod++;
+	meta->gso_type = XEN_NETIF_GSO_TYPE_NONE;
+	meta->gso_size = 0;
+	meta->size = 0;
+	meta->id = req->id;
+
+	npo->copy_off = 0;
+	npo->copy_gref = req->gref;
+
+	return meta;
+}
+
+/*
+ * Set up the grant operations for this fragment. If it's a flipping
+ * interface, we also set up the unmap request from here.
+ */
+static void xenvif_gop_frag_copy(struct xenvif_queue *queue, struct sk_buff *skb,
+				 struct netrx_pending_operations *npo,
+				 struct page *page, unsigned long size,
+				 unsigned long offset, int *head)
+{
+	struct gnttab_copy *copy_gop;
+	struct xenvif_rx_meta *meta;
+	unsigned long bytes;
+	int gso_type = XEN_NETIF_GSO_TYPE_NONE;
+
+	/* Data must not cross a page boundary. */
+	BUG_ON(size + offset > PAGE_SIZE<<compound_order(page));
+
+	meta = npo->meta + npo->meta_prod - 1;
+
+	/* Skip unused frames from start of page */
+	page += offset >> PAGE_SHIFT;
+	offset &= ~PAGE_MASK;
+
+	while (size > 0) {
+		struct xen_page_foreign *foreign;
+
+		BUG_ON(offset >= PAGE_SIZE);
+		BUG_ON(npo->copy_off > MAX_BUFFER_OFFSET);
+
+		if (npo->copy_off == MAX_BUFFER_OFFSET)
+			meta = get_next_rx_buffer(queue, npo);
+
+		bytes = PAGE_SIZE - offset;
+		if (bytes > size)
+			bytes = size;
+
+		if (npo->copy_off + bytes > MAX_BUFFER_OFFSET)
+			bytes = MAX_BUFFER_OFFSET - npo->copy_off;
+
+		copy_gop = npo->copy + npo->copy_prod++;
+		copy_gop->flags = GNTCOPY_dest_gref;
+		copy_gop->len = bytes;
+
+		foreign = xen_page_foreign(page);
+		if (foreign) {
+			copy_gop->source.domid = foreign->domid;
+			copy_gop->source.u.ref = foreign->gref;
+			copy_gop->flags |= GNTCOPY_source_gref;
+		} else {
+			copy_gop->source.domid = DOMID_SELF;
+			copy_gop->source.u.gmfn =
+				virt_to_mfn(page_address(page));
+		}
+		copy_gop->source.offset = offset;
+
+		copy_gop->dest.domid = queue->vif->domid;
+		copy_gop->dest.offset = npo->copy_off;
+		copy_gop->dest.u.ref = npo->copy_gref;
+
+		npo->copy_off += bytes;
+		meta->size += bytes;
+
+		offset += bytes;
+		size -= bytes;
+
+		/* Next frame */
+		if (offset == PAGE_SIZE && size) {
+			BUG_ON(!PageCompound(page));
+			page++;
+			offset = 0;
+		}
+
+		/* Leave a gap for the GSO descriptor. */
+		if (skb_is_gso(skb)) {
+			if (skb_shinfo(skb)->gso_type & SKB_GSO_TCPV4)
+				gso_type = XEN_NETIF_GSO_TYPE_TCPV4;
+			else if (skb_shinfo(skb)->gso_type & SKB_GSO_TCPV6)
+				gso_type = XEN_NETIF_GSO_TYPE_TCPV6;
+		}
+
+		if (*head && ((1 << gso_type) & queue->vif->gso_mask))
+			queue->rx.req_cons++;
+
+		*head = 0; /* There must be something in this buffer now. */
+
+	}
+}
+
+/*
+ * Prepare an SKB to be transmitted to the frontend.
+ *
+ * This function is responsible for allocating grant operations, meta
+ * structures, etc.
+ *
+ * It returns the number of meta structures consumed. The number of
+ * ring slots used is always equal to the number of meta slots used
+ * plus the number of GSO descriptors used. Currently, we use either
+ * zero GSO descriptors (for non-GSO packets) or one descriptor (for
+ * frontend-side LRO).
+ */
+static int xenvif_gop_skb(struct sk_buff *skb,
+			  struct netrx_pending_operations *npo,
+			  struct xenvif_queue *queue)
+{
+	struct xenvif *vif = netdev_priv(skb->dev);
+	int nr_frags = skb_shinfo(skb)->nr_frags;
+	int i;
+	struct xen_netif_rx_request *req;
+	struct xenvif_rx_meta *meta;
+	unsigned char *data;
+	int head = 1;
+	int old_meta_prod;
+	int gso_type;
+
+	old_meta_prod = npo->meta_prod;
+
+	gso_type = XEN_NETIF_GSO_TYPE_NONE;
+	if (skb_is_gso(skb)) {
+		if (skb_shinfo(skb)->gso_type & SKB_GSO_TCPV4)
+			gso_type = XEN_NETIF_GSO_TYPE_TCPV4;
+		else if (skb_shinfo(skb)->gso_type & SKB_GSO_TCPV6)
+			gso_type = XEN_NETIF_GSO_TYPE_TCPV6;
+	}
+
+	/* Set up a GSO prefix descriptor, if necessary */
+	if ((1 << gso_type) & vif->gso_prefix_mask) {
+		req = RING_GET_REQUEST(&queue->rx, queue->rx.req_cons++);
+		meta = npo->meta + npo->meta_prod++;
+		meta->gso_type = gso_type;
+		meta->gso_size = skb_shinfo(skb)->gso_size;
+		meta->size = 0;
+		meta->id = req->id;
+	}
+
+	req = RING_GET_REQUEST(&queue->rx, queue->rx.req_cons++);
+	meta = npo->meta + npo->meta_prod++;
+
+	if ((1 << gso_type) & vif->gso_mask) {
+		meta->gso_type = gso_type;
+		meta->gso_size = skb_shinfo(skb)->gso_size;
+	} else {
+		meta->gso_type = XEN_NETIF_GSO_TYPE_NONE;
+		meta->gso_size = 0;
+	}
+
+	meta->size = 0;
+	meta->id = req->id;
+	npo->copy_off = 0;
+	npo->copy_gref = req->gref;
+
+	data = skb->data;
+	while (data < skb_tail_pointer(skb)) {
+		unsigned int offset = offset_in_page(data);
+		unsigned int len = PAGE_SIZE - offset;
+
+		if (data + len > skb_tail_pointer(skb))
+			len = skb_tail_pointer(skb) - data;
+
+		xenvif_gop_frag_copy(queue, skb, npo,
+				     virt_to_page(data), len, offset, &head);
+		data += len;
+	}
+
+	for (i = 0; i < nr_frags; i++) {
+		xenvif_gop_frag_copy(queue, skb, npo,
+				     skb_frag_page(&skb_shinfo(skb)->frags[i]),
+				     skb_frag_size(&skb_shinfo(skb)->frags[i]),
+				     skb_shinfo(skb)->frags[i].page_offset,
+				     &head);
+	}
+
+	return npo->meta_prod - old_meta_prod;
+}
+
+/*
+ * This is a twin to xenvif_gop_skb.  Assume that xenvif_gop_skb was
+ * used to set up the operations on the top of
+ * netrx_pending_operations, which have since been done.  Check that
+ * they didn't give any errors and advance over them.
+ */
+static int xenvif_check_gop(struct xenvif *vif, int nr_meta_slots,
+			    struct netrx_pending_operations *npo)
+{
+	struct gnttab_copy     *copy_op;
+	int status = XEN_NETIF_RSP_OKAY;
+	int i;
+
+	for (i = 0; i < nr_meta_slots; i++) {
+		copy_op = npo->copy + npo->copy_cons++;
+		if (copy_op->status != GNTST_okay) {
+			netdev_dbg(vif->dev,
+				   "Bad status %d from copy to DOM%d.\n",
+				   copy_op->status, vif->domid);
+			status = XEN_NETIF_RSP_ERROR;
+		}
+	}
+
+	return status;
+}
+
+static void xenvif_add_frag_responses(struct xenvif_queue *queue, int status,
+				      struct xenvif_rx_meta *meta,
+				      int nr_meta_slots)
+{
+	int i;
+	unsigned long offset;
+
+	/* No fragments used */
+	if (nr_meta_slots <= 1)
+		return;
+
+	nr_meta_slots--;
+
+	for (i = 0; i < nr_meta_slots; i++) {
+		int flags;
+		if (i == nr_meta_slots - 1)
+			flags = 0;
+		else
+			flags = XEN_NETRXF_more_data;
+
+		offset = 0;
+		make_rx_response(queue, meta[i].id, status, offset,
+				 meta[i].size, flags);
+	}
+}
+
+void xenvif_kick_thread(struct xenvif_queue *queue)
+{
+	wake_up(&queue->wq);
+}
+
+static void xenvif_rx_action(struct xenvif_queue *queue)
+{
+	s8 status;
+	u16 flags;
+	struct xen_netif_rx_response *resp;
+	struct sk_buff_head rxq;
+	struct sk_buff *skb;
+	LIST_HEAD(notify);
+	int ret;
+	unsigned long offset;
+	bool need_to_notify = false;
+
+	struct netrx_pending_operations npo = {
+		.copy  = queue->grant_copy_op,
+		.meta  = queue->meta,
+	};
+
+	skb_queue_head_init(&rxq);
+
+	while (xenvif_rx_ring_slots_available(queue, XEN_NETBK_RX_SLOTS_MAX)
+	       && (skb = xenvif_rx_dequeue(queue)) != NULL) {
+		RING_IDX old_req_cons;
+		RING_IDX ring_slots_used;
+
+		queue->last_rx_time = jiffies;
+
+		old_req_cons = queue->rx.req_cons;
+		XENVIF_RX_CB(skb)->meta_slots_used = xenvif_gop_skb(skb, &npo, queue);
+		ring_slots_used = queue->rx.req_cons - old_req_cons;
+
+		__skb_queue_tail(&rxq, skb);
+	}
+
+	BUG_ON(npo.meta_prod > ARRAY_SIZE(queue->meta));
+
+	if (!npo.copy_prod)
+		goto done;
+
+	BUG_ON(npo.copy_prod > MAX_GRANT_COPY_OPS);
+	gnttab_batch_copy(queue->grant_copy_op, npo.copy_prod);
+
+	while ((skb = __skb_dequeue(&rxq)) != NULL) {
+
+		if ((1 << queue->meta[npo.meta_cons].gso_type) &
+		    queue->vif->gso_prefix_mask) {
+			resp = RING_GET_RESPONSE(&queue->rx,
+						 queue->rx.rsp_prod_pvt++);
+
+			resp->flags = XEN_NETRXF_gso_prefix | XEN_NETRXF_more_data;
+
+			resp->offset = queue->meta[npo.meta_cons].gso_size;
+			resp->id = queue->meta[npo.meta_cons].id;
+			resp->status = XENVIF_RX_CB(skb)->meta_slots_used;
+
+			npo.meta_cons++;
+			XENVIF_RX_CB(skb)->meta_slots_used--;
+		}
+
+
+		queue->stats.tx_bytes += skb->len;
+		queue->stats.tx_packets++;
+
+		status = xenvif_check_gop(queue->vif,
+					  XENVIF_RX_CB(skb)->meta_slots_used,
+					  &npo);
+
+		if (XENVIF_RX_CB(skb)->meta_slots_used == 1)
+			flags = 0;
+		else
+			flags = XEN_NETRXF_more_data;
+
+		if (skb->ip_summed == CHECKSUM_PARTIAL) /* local packet? */
+			flags |= XEN_NETRXF_csum_blank | XEN_NETRXF_data_validated;
+		else if (skb->ip_summed == CHECKSUM_UNNECESSARY)
+			/* remote but checksummed. */
+			flags |= XEN_NETRXF_data_validated;
+
+		offset = 0;
+		resp = make_rx_response(queue, queue->meta[npo.meta_cons].id,
+					status, offset,
+					queue->meta[npo.meta_cons].size,
+					flags);
+
+		if ((1 << queue->meta[npo.meta_cons].gso_type) &
+		    queue->vif->gso_mask) {
+			struct xen_netif_extra_info *gso =
+				(struct xen_netif_extra_info *)
+				RING_GET_RESPONSE(&queue->rx,
+						  queue->rx.rsp_prod_pvt++);
+
+			resp->flags |= XEN_NETRXF_extra_info;
+
+			gso->u.gso.type = queue->meta[npo.meta_cons].gso_type;
+			gso->u.gso.size = queue->meta[npo.meta_cons].gso_size;
+			gso->u.gso.pad = 0;
+			gso->u.gso.features = 0;
+
+			gso->type = XEN_NETIF_EXTRA_TYPE_GSO;
+			gso->flags = 0;
+		}
+
+		xenvif_add_frag_responses(queue, status,
+					  queue->meta + npo.meta_cons + 1,
+					  XENVIF_RX_CB(skb)->meta_slots_used);
+
+		RING_PUSH_RESPONSES_AND_CHECK_NOTIFY(&queue->rx, ret);
+
+		need_to_notify |= !!ret;
+
+		npo.meta_cons += XENVIF_RX_CB(skb)->meta_slots_used;
+		dev_kfree_skb(skb);
+	}
+
+done:
+	if (need_to_notify)
+		notify_remote_via_irq(queue->rx_irq);
+}
+
+void xenvif_napi_schedule_or_enable_events(struct xenvif_queue *queue)
+{
+	int more_to_do;
+
+	RING_FINAL_CHECK_FOR_REQUESTS(&queue->tx, more_to_do);
+
+	if (more_to_do)
+		napi_schedule(&queue->napi);
+}
+
+static void tx_add_credit(struct xenvif_queue *queue)
+{
+	unsigned long max_burst, max_credit;
+
+	/*
+	 * Allow a burst big enough to transmit a jumbo packet of up to 128kB.
+	 * Otherwise the interface can seize up due to insufficient credit.
+	 */
+	max_burst = RING_GET_REQUEST(&queue->tx, queue->tx.req_cons)->size;
+	max_burst = min(max_burst, 131072UL);
+	max_burst = max(max_burst, queue->credit_bytes);
+
+	/* Take care that adding a new chunk of credit doesn't wrap to zero. */
+	max_credit = queue->remaining_credit + queue->credit_bytes;
+	if (max_credit < queue->remaining_credit)
+		max_credit = ULONG_MAX; /* wrapped: clamp to ULONG_MAX */
+
+	queue->remaining_credit = min(max_credit, max_burst);
+}
+
+void xenvif_tx_credit_callback(unsigned long data)
+{
+	struct xenvif_queue *queue = (struct xenvif_queue *)data;
+	tx_add_credit(queue);
+	xenvif_napi_schedule_or_enable_events(queue);
+}
+
+static void xenvif_tx_err(struct xenvif_queue *queue,
+			  struct xen_netif_tx_request *txp, RING_IDX end)
+{
+	RING_IDX cons = queue->tx.req_cons;
+	unsigned long flags;
+
+	do {
+		spin_lock_irqsave(&queue->response_lock, flags);
+		make_tx_response(queue, txp, XEN_NETIF_RSP_ERROR);
+		push_tx_responses(queue);
+		spin_unlock_irqrestore(&queue->response_lock, flags);
+		if (cons == end)
+			break;
+		txp = RING_GET_REQUEST(&queue->tx, cons++);
+	} while (1);
+	queue->tx.req_cons = cons;
+}
+
+static void xenvif_fatal_tx_err(struct xenvif *vif)
+{
+	netdev_err(vif->dev, "fatal error; disabling device\n");
+	vif->disabled = true;
+	/* Disable the vif from queue 0's kthread */
+	if (vif->queues)
+		xenvif_kick_thread(&vif->queues[0]);
+}
+
+static int xenvif_count_requests(struct xenvif_queue *queue,
+				 struct xen_netif_tx_request *first,
+				 struct xen_netif_tx_request *txp,
+				 int work_to_do)
+{
+	RING_IDX cons = queue->tx.req_cons;
+	int slots = 0;
+	int drop_err = 0;
+	int more_data;
+
+	if (!(first->flags & XEN_NETTXF_more_data))
+		return 0;
+
+	do {
+		struct xen_netif_tx_request dropped_tx = { 0 };
+
+		if (slots >= work_to_do) {
+			netdev_err(queue->vif->dev,
+				   "Asked for %d slots but exceeds this limit\n",
+				   work_to_do);
+			xenvif_fatal_tx_err(queue->vif);
+			return -ENODATA;
+		}
+
+		/* This guest is really using too many slots and
+		 * considered malicious.
+		 */
+		if (unlikely(slots >= fatal_skb_slots)) {
+			netdev_err(queue->vif->dev,
+				   "Malicious frontend using %d slots, threshold %u\n",
+				   slots, fatal_skb_slots);
+			xenvif_fatal_tx_err(queue->vif);
+			return -E2BIG;
+		}
+
+		/* Xen network protocol had implicit dependency on
+		 * MAX_SKB_FRAGS. XEN_NETBK_LEGACY_SLOTS_MAX is set to
+		 * the historical MAX_SKB_FRAGS value 18 to honor the
+		 * same behavior as before. Any packet using more than
+		 * 18 slots but less than fatal_skb_slots slots is
+		 * dropped
+		 */
+		if (!drop_err && slots >= XEN_NETBK_LEGACY_SLOTS_MAX) {
+			if (net_ratelimit())
+				netdev_dbg(queue->vif->dev,
+					   "Too many slots (%d) exceeding limit (%d), dropping packet\n",
+					   slots, XEN_NETBK_LEGACY_SLOTS_MAX);
+			drop_err = -E2BIG;
+		}
+
+		if (drop_err)
+			txp = &dropped_tx;
+
+		memcpy(txp, RING_GET_REQUEST(&queue->tx, cons + slots),
+		       sizeof(*txp));
+
+		/* If the guest submitted a frame >= 64 KiB then
+		 * first->size overflowed and following slots will
+		 * appear to be larger than the frame.
+		 *
+		 * This cannot be fatal error as there are buggy
+		 * frontends that do this.
+		 *
+		 * Consume all slots and drop the packet.
+		 */
+		if (!drop_err && txp->size > first->size) {
+			if (net_ratelimit())
+				netdev_dbg(queue->vif->dev,
+					   "Invalid tx request, slot size %u > remaining size %u\n",
+					   txp->size, first->size);
+			drop_err = -EIO;
+		}
+
+		first->size -= txp->size;
+		slots++;
+
+		if (unlikely((txp->offset + txp->size) > PAGE_SIZE)) {
+			netdev_err(queue->vif->dev, "Cross page boundary, txp->offset: %x, size: %u\n",
+				 txp->offset, txp->size);
+			xenvif_fatal_tx_err(queue->vif);
+			return -EINVAL;
+		}
+
+		more_data = txp->flags & XEN_NETTXF_more_data;
+
+		if (!drop_err)
+			txp++;
+
+	} while (more_data);
+
+	if (drop_err) {
+		xenvif_tx_err(queue, first, cons + slots);
+		return drop_err;
+	}
+
+	return slots;
+}
+
+
+struct xenvif_tx_cb {
+	u16 pending_idx;
+};
+
+#define XENVIF_TX_CB(skb) ((struct xenvif_tx_cb *)(skb)->cb)
+
+static inline void xenvif_tx_create_map_op(struct xenvif_queue *queue,
+					  u16 pending_idx,
+					  struct xen_netif_tx_request *txp,
+					  struct gnttab_map_grant_ref *mop)
+{
+	queue->pages_to_map[mop-queue->tx_map_ops] = queue->mmap_pages[pending_idx];
+	gnttab_set_map_op(mop, idx_to_kaddr(queue, pending_idx),
+			  GNTMAP_host_map | GNTMAP_readonly,
+			  txp->gref, queue->vif->domid);
+
+	memcpy(&queue->pending_tx_info[pending_idx].req, txp,
+	       sizeof(*txp));
+}
+
+static inline struct sk_buff *xenvif_alloc_skb(unsigned int size)
+{
+	struct sk_buff *skb =
+		alloc_skb(size + NET_SKB_PAD + NET_IP_ALIGN,
+			  GFP_ATOMIC | __GFP_NOWARN);
+	if (unlikely(skb == NULL))
+		return NULL;
+
+	/* Packets passed to netif_rx() must have some headroom. */
+	skb_reserve(skb, NET_SKB_PAD + NET_IP_ALIGN);
+
+	/* Initialize it here to avoid later surprises */
+	skb_shinfo(skb)->destructor_arg = NULL;
+
+	return skb;
+}
+
+static struct gnttab_map_grant_ref *xenvif_get_requests(struct xenvif_queue *queue,
+							struct sk_buff *skb,
+							struct xen_netif_tx_request *txp,
+							struct gnttab_map_grant_ref *gop)
+{
+	struct skb_shared_info *shinfo = skb_shinfo(skb);
+	skb_frag_t *frags = shinfo->frags;
+	u16 pending_idx = XENVIF_TX_CB(skb)->pending_idx;
+	int start;
+	pending_ring_idx_t index;
+	unsigned int nr_slots, frag_overflow = 0;
+
+	/* At this point shinfo->nr_frags is in fact the number of
+	 * slots, which can be as large as XEN_NETBK_LEGACY_SLOTS_MAX.
+	 */
+	if (shinfo->nr_frags > MAX_SKB_FRAGS) {
+		frag_overflow = shinfo->nr_frags - MAX_SKB_FRAGS;
+		BUG_ON(frag_overflow > MAX_SKB_FRAGS);
+		shinfo->nr_frags = MAX_SKB_FRAGS;
+	}
+	nr_slots = shinfo->nr_frags;
+
+	/* Skip first skb fragment if it is on same page as header fragment. */
+	start = (frag_get_pending_idx(&shinfo->frags[0]) == pending_idx);
+
+	for (shinfo->nr_frags = start; shinfo->nr_frags < nr_slots;
+	     shinfo->nr_frags++, txp++, gop++) {
+		index = pending_index(queue->pending_cons++);
+		pending_idx = queue->pending_ring[index];
+		xenvif_tx_create_map_op(queue, pending_idx, txp, gop);
+		frag_set_pending_idx(&frags[shinfo->nr_frags], pending_idx);
+	}
+
+	if (frag_overflow) {
+		struct sk_buff *nskb = xenvif_alloc_skb(0);
+		if (unlikely(nskb == NULL)) {
+			if (net_ratelimit())
+				netdev_err(queue->vif->dev,
+					   "Can't allocate the frag_list skb.\n");
+			return NULL;
+		}
+
+		shinfo = skb_shinfo(nskb);
+		frags = shinfo->frags;
+
+		for (shinfo->nr_frags = 0; shinfo->nr_frags < frag_overflow;
+		     shinfo->nr_frags++, txp++, gop++) {
+			index = pending_index(queue->pending_cons++);
+			pending_idx = queue->pending_ring[index];
+			xenvif_tx_create_map_op(queue, pending_idx, txp, gop);
+			frag_set_pending_idx(&frags[shinfo->nr_frags],
+					     pending_idx);
+		}
+
+		skb_shinfo(skb)->frag_list = nskb;
+	}
+
+	return gop;
+}
+
+static inline void xenvif_grant_handle_set(struct xenvif_queue *queue,
+					   u16 pending_idx,
+					   grant_handle_t handle)
+{
+	if (unlikely(queue->grant_tx_handle[pending_idx] !=
+		     NETBACK_INVALID_HANDLE)) {
+		netdev_err(queue->vif->dev,
+			   "Trying to overwrite active handle! pending_idx: %x\n",
+			   pending_idx);
+		BUG();
+	}
+	queue->grant_tx_handle[pending_idx] = handle;
+}
+
+static inline void xenvif_grant_handle_reset(struct xenvif_queue *queue,
+					     u16 pending_idx)
+{
+	if (unlikely(queue->grant_tx_handle[pending_idx] ==
+		     NETBACK_INVALID_HANDLE)) {
+		netdev_err(queue->vif->dev,
+			   "Trying to unmap invalid handle! pending_idx: %x\n",
+			   pending_idx);
+		BUG();
+	}
+	queue->grant_tx_handle[pending_idx] = NETBACK_INVALID_HANDLE;
+}
+
+static int xenvif_tx_check_gop(struct xenvif_queue *queue,
+			       struct sk_buff *skb,
+			       struct gnttab_map_grant_ref **gopp_map,
+			       struct gnttab_copy **gopp_copy)
+{
+	struct gnttab_map_grant_ref *gop_map = *gopp_map;
+	u16 pending_idx = XENVIF_TX_CB(skb)->pending_idx;
+	/* This always points to the shinfo of the skb being checked, which
+	 * could be either the first or the one on the frag_list
+	 */
+	struct skb_shared_info *shinfo = skb_shinfo(skb);
+	/* If this is non-NULL, we are currently checking the frag_list skb, and
+	 * this points to the shinfo of the first one
+	 */
+	struct skb_shared_info *first_shinfo = NULL;
+	int nr_frags = shinfo->nr_frags;
+	const bool sharedslot = nr_frags &&
+				frag_get_pending_idx(&shinfo->frags[0]) == pending_idx;
+	int i, err;
+
+	/* Check status of header. */
+	err = (*gopp_copy)->status;
+	if (unlikely(err)) {
+		if (net_ratelimit())
+			netdev_dbg(queue->vif->dev,
+				   "Grant copy of header failed! status: %d pending_idx: %u ref: %u\n",
+				   (*gopp_copy)->status,
+				   pending_idx,
+				   (*gopp_copy)->source.u.ref);
+		/* The first frag might still have this slot mapped */
+		if (!sharedslot)
+			xenvif_idx_release(queue, pending_idx,
+					   XEN_NETIF_RSP_ERROR);
+	}
+	(*gopp_copy)++;
+
+check_frags:
+	for (i = 0; i < nr_frags; i++, gop_map++) {
+		int j, newerr;
+
+		pending_idx = frag_get_pending_idx(&shinfo->frags[i]);
+
+		/* Check error status: if okay then remember grant handle. */
+		newerr = gop_map->status;
+
+		if (likely(!newerr)) {
+			xenvif_grant_handle_set(queue,
+						pending_idx,
+						gop_map->handle);
+			/* Had a previous error? Invalidate this fragment. */
+			if (unlikely(err)) {
+				xenvif_idx_unmap(queue, pending_idx);
+				/* If the mapping of the first frag was OK, but
+				 * the header's copy failed, and they are
+				 * sharing a slot, send an error
+				 */
+				if (i == 0 && sharedslot)
+					xenvif_idx_release(queue, pending_idx,
+							   XEN_NETIF_RSP_ERROR);
+				else
+					xenvif_idx_release(queue, pending_idx,
+							   XEN_NETIF_RSP_OKAY);
+			}
+			continue;
+		}
+
+		/* Error on this fragment: respond to client with an error. */
+		if (net_ratelimit())
+			netdev_dbg(queue->vif->dev,
+				   "Grant map of %d. frag failed! status: %d pending_idx: %u ref: %u\n",
+				   i,
+				   gop_map->status,
+				   pending_idx,
+				   gop_map->ref);
+
+		xenvif_idx_release(queue, pending_idx, XEN_NETIF_RSP_ERROR);
+
+		/* Not the first error? Preceding frags already invalidated. */
+		if (err)
+			continue;
+
+		/* First error: if the header haven't shared a slot with the
+		 * first frag, release it as well.
+		 */
+		if (!sharedslot)
+			xenvif_idx_release(queue,
+					   XENVIF_TX_CB(skb)->pending_idx,
+					   XEN_NETIF_RSP_OKAY);
+
+		/* Invalidate preceding fragments of this skb. */
+		for (j = 0; j < i; j++) {
+			pending_idx = frag_get_pending_idx(&shinfo->frags[j]);
+			xenvif_idx_unmap(queue, pending_idx);
+			xenvif_idx_release(queue, pending_idx,
+					   XEN_NETIF_RSP_OKAY);
+		}
+
+		/* And if we found the error while checking the frag_list, unmap
+		 * the first skb's frags
+		 */
+		if (first_shinfo) {
+			for (j = 0; j < first_shinfo->nr_frags; j++) {
+				pending_idx = frag_get_pending_idx(&first_shinfo->frags[j]);
+				xenvif_idx_unmap(queue, pending_idx);
+				xenvif_idx_release(queue, pending_idx,
+						   XEN_NETIF_RSP_OKAY);
+			}
+		}
+
+		/* Remember the error: invalidate all subsequent fragments. */
+		err = newerr;
+	}
+
+	if (skb_has_frag_list(skb) && !first_shinfo) {
+		first_shinfo = skb_shinfo(skb);
+		shinfo = skb_shinfo(skb_shinfo(skb)->frag_list);
+		nr_frags = shinfo->nr_frags;
+
+		goto check_frags;
+	}
+
+	*gopp_map = gop_map;
+	return err;
+}
+
+static void xenvif_fill_frags(struct xenvif_queue *queue, struct sk_buff *skb)
+{
+	struct skb_shared_info *shinfo = skb_shinfo(skb);
+	int nr_frags = shinfo->nr_frags;
+	int i;
+	u16 prev_pending_idx = INVALID_PENDING_IDX;
+
+	for (i = 0; i < nr_frags; i++) {
+		skb_frag_t *frag = shinfo->frags + i;
+		struct xen_netif_tx_request *txp;
+		struct page *page;
+		u16 pending_idx;
+
+		pending_idx = frag_get_pending_idx(frag);
+
+		/* If this is not the first frag, chain it to the previous*/
+		if (prev_pending_idx == INVALID_PENDING_IDX)
+			skb_shinfo(skb)->destructor_arg =
+				&callback_param(queue, pending_idx);
+		else
+			callback_param(queue, prev_pending_idx).ctx =
+				&callback_param(queue, pending_idx);
+
+		callback_param(queue, pending_idx).ctx = NULL;
+		prev_pending_idx = pending_idx;
+
+		txp = &queue->pending_tx_info[pending_idx].req;
+		page = virt_to_page(idx_to_kaddr(queue, pending_idx));
+		__skb_fill_page_desc(skb, i, page, txp->offset, txp->size);
+		skb->len += txp->size;
+		skb->data_len += txp->size;
+		skb->truesize += txp->size;
+
+		/* Take an extra reference to offset network stack's put_page */
+		get_page(queue->mmap_pages[pending_idx]);
+	}
+}
+
+static int xenvif_get_extras(struct xenvif_queue *queue,
+				struct xen_netif_extra_info *extras,
+				int work_to_do)
+{
+	struct xen_netif_extra_info extra;
+	RING_IDX cons = queue->tx.req_cons;
+
+	do {
+		if (unlikely(work_to_do-- <= 0)) {
+			netdev_err(queue->vif->dev, "Missing extra info\n");
+			xenvif_fatal_tx_err(queue->vif);
+			return -EBADR;
+		}
+
+		memcpy(&extra, RING_GET_REQUEST(&queue->tx, cons),
+		       sizeof(extra));
+		if (unlikely(!extra.type ||
+			     extra.type >= XEN_NETIF_EXTRA_TYPE_MAX)) {
+			queue->tx.req_cons = ++cons;
+			netdev_err(queue->vif->dev,
+				   "Invalid extra type: %d\n", extra.type);
+			xenvif_fatal_tx_err(queue->vif);
+			return -EINVAL;
+		}
+
+		memcpy(&extras[extra.type - 1], &extra, sizeof(extra));
+		queue->tx.req_cons = ++cons;
+	} while (extra.flags & XEN_NETIF_EXTRA_FLAG_MORE);
+
+	return work_to_do;
+}
+
+static int xenvif_set_skb_gso(struct xenvif *vif,
+			      struct sk_buff *skb,
+			      struct xen_netif_extra_info *gso)
+{
+	if (!gso->u.gso.size) {
+		netdev_err(vif->dev, "GSO size must not be zero.\n");
+		xenvif_fatal_tx_err(vif);
+		return -EINVAL;
+	}
+
+	switch (gso->u.gso.type) {
+	case XEN_NETIF_GSO_TYPE_TCPV4:
+		skb_shinfo(skb)->gso_type = SKB_GSO_TCPV4;
+		break;
+	case XEN_NETIF_GSO_TYPE_TCPV6:
+		skb_shinfo(skb)->gso_type = SKB_GSO_TCPV6;
+		break;
+	default:
+		netdev_err(vif->dev, "Bad GSO type %d.\n", gso->u.gso.type);
+		xenvif_fatal_tx_err(vif);
+		return -EINVAL;
+	}
+
+	skb_shinfo(skb)->gso_size = gso->u.gso.size;
+	/* gso_segs will be calculated later */
+
+	return 0;
+}
+
+static int checksum_setup(struct xenvif_queue *queue, struct sk_buff *skb)
+{
+	bool recalculate_partial_csum = false;
+
+	/* A GSO SKB must be CHECKSUM_PARTIAL. However some buggy
+	 * peers can fail to set NETRXF_csum_blank when sending a GSO
+	 * frame. In this case force the SKB to CHECKSUM_PARTIAL and
+	 * recalculate the partial checksum.
+	 */
+	if (skb->ip_summed != CHECKSUM_PARTIAL && skb_is_gso(skb)) {
+		queue->stats.rx_gso_checksum_fixup++;
+		skb->ip_summed = CHECKSUM_PARTIAL;
+		recalculate_partial_csum = true;
+	}
+
+	/* A non-CHECKSUM_PARTIAL SKB does not require setup. */
+	if (skb->ip_summed != CHECKSUM_PARTIAL)
+		return 0;
+
+	return skb_checksum_setup(skb, recalculate_partial_csum);
+}
+
+static bool tx_credit_exceeded(struct xenvif_queue *queue, unsigned size)
+{
+	u64 now = get_jiffies_64();
+	u64 next_credit = queue->credit_window_start +
+		msecs_to_jiffies(queue->credit_usec / 1000);
+
+	/* Timer could already be pending in rare cases. */
+	if (timer_pending(&queue->credit_timeout))
+		return true;
+
+	/* Passed the point where we can replenish credit? */
+	if (time_after_eq64(now, next_credit)) {
+		queue->credit_window_start = now;
+		tx_add_credit(queue);
+	}
+
+	/* Still too big to send right now? Set a callback. */
+	if (size > queue->remaining_credit) {
+		queue->credit_timeout.data     =
+			(unsigned long)queue;
+		mod_timer(&queue->credit_timeout,
+			  next_credit);
+		queue->credit_window_start = next_credit;
+
+		return true;
+	}
+
+	return false;
+}
+
+static void xenvif_tx_build_gops(struct xenvif_queue *queue,
+				     int budget,
+				     unsigned *copy_ops,
+				     unsigned *map_ops)
+{
+	struct gnttab_map_grant_ref *gop = queue->tx_map_ops, *request_gop;
+	struct sk_buff *skb;
+	int ret;
+
+	while (skb_queue_len(&queue->tx_queue) < budget) {
+		struct xen_netif_tx_request txreq;
+		struct xen_netif_tx_request txfrags[XEN_NETBK_LEGACY_SLOTS_MAX];
+		struct xen_netif_extra_info extras[XEN_NETIF_EXTRA_TYPE_MAX-1];
+		u16 pending_idx;
+		RING_IDX idx;
+		int work_to_do;
+		unsigned int data_len;
+		pending_ring_idx_t index;
+
+		if (queue->tx.sring->req_prod - queue->tx.req_cons >
+		    XEN_NETIF_TX_RING_SIZE) {
+			netdev_err(queue->vif->dev,
+				   "Impossible number of requests. "
+				   "req_prod %d, req_cons %d, size %ld\n",
+				   queue->tx.sring->req_prod, queue->tx.req_cons,
+				   XEN_NETIF_TX_RING_SIZE);
+			xenvif_fatal_tx_err(queue->vif);
+			break;
+		}
+
+		work_to_do = RING_HAS_UNCONSUMED_REQUESTS(&queue->tx);
+		if (!work_to_do)
+			break;
+
+		idx = queue->tx.req_cons;
+		rmb(); /* Ensure that we see the request before we copy it. */
+		memcpy(&txreq, RING_GET_REQUEST(&queue->tx, idx), sizeof(txreq));
+
+		/* Credit-based scheduling. */
+		if (txreq.size > queue->remaining_credit &&
+		    tx_credit_exceeded(queue, txreq.size))
+			break;
+
+		queue->remaining_credit -= txreq.size;
+
+		work_to_do--;
+		queue->tx.req_cons = ++idx;
+
+		memset(extras, 0, sizeof(extras));
+		if (txreq.flags & XEN_NETTXF_extra_info) {
+			work_to_do = xenvif_get_extras(queue, extras,
+						       work_to_do);
+			idx = queue->tx.req_cons;
+			if (unlikely(work_to_do < 0))
+				break;
+		}
+
+		ret = xenvif_count_requests(queue, &txreq, txfrags, work_to_do);
+		if (unlikely(ret < 0))
+			break;
+
+		idx += ret;
+
+		if (unlikely(txreq.size < ETH_HLEN)) {
+			netdev_dbg(queue->vif->dev,
+				   "Bad packet size: %d\n", txreq.size);
+			xenvif_tx_err(queue, &txreq, idx);
+			break;
+		}
+
+		/* No crossing a page as the payload mustn't fragment. */
+		if (unlikely((txreq.offset + txreq.size) > PAGE_SIZE)) {
+			netdev_err(queue->vif->dev,
+				   "txreq.offset: %x, size: %u, end: %lu\n",
+				   txreq.offset, txreq.size,
+				   (unsigned long)(txreq.offset&~PAGE_MASK) + txreq.size);
+			xenvif_fatal_tx_err(queue->vif);
+			break;
+		}
+
+		index = pending_index(queue->pending_cons);
+		pending_idx = queue->pending_ring[index];
+
+		data_len = (txreq.size > XEN_NETBACK_TX_COPY_LEN &&
+			    ret < XEN_NETBK_LEGACY_SLOTS_MAX) ?
+			XEN_NETBACK_TX_COPY_LEN : txreq.size;
+
+		skb = xenvif_alloc_skb(data_len);
+		if (unlikely(skb == NULL)) {
+			netdev_dbg(queue->vif->dev,
+				   "Can't allocate a skb in start_xmit.\n");
+			xenvif_tx_err(queue, &txreq, idx);
+			break;
+		}
+
+		if (extras[XEN_NETIF_EXTRA_TYPE_GSO - 1].type) {
+			struct xen_netif_extra_info *gso;
+			gso = &extras[XEN_NETIF_EXTRA_TYPE_GSO - 1];
+
+			if (xenvif_set_skb_gso(queue->vif, skb, gso)) {
+				/* Failure in xenvif_set_skb_gso is fatal. */
+				kfree_skb(skb);
+				break;
+			}
+		}
+
+		XENVIF_TX_CB(skb)->pending_idx = pending_idx;
+
+		__skb_put(skb, data_len);
+		queue->tx_copy_ops[*copy_ops].source.u.ref = txreq.gref;
+		queue->tx_copy_ops[*copy_ops].source.domid = queue->vif->domid;
+		queue->tx_copy_ops[*copy_ops].source.offset = txreq.offset;
+
+		queue->tx_copy_ops[*copy_ops].dest.u.gmfn =
+			virt_to_mfn(skb->data);
+		queue->tx_copy_ops[*copy_ops].dest.domid = DOMID_SELF;
+		queue->tx_copy_ops[*copy_ops].dest.offset =
+			offset_in_page(skb->data);
+
+		queue->tx_copy_ops[*copy_ops].len = data_len;
+		queue->tx_copy_ops[*copy_ops].flags = GNTCOPY_source_gref;
+
+		(*copy_ops)++;
+
+		skb_shinfo(skb)->nr_frags = ret;
+		if (data_len < txreq.size) {
+			skb_shinfo(skb)->nr_frags++;
+			frag_set_pending_idx(&skb_shinfo(skb)->frags[0],
+					     pending_idx);
+			xenvif_tx_create_map_op(queue, pending_idx, &txreq, gop);
+			gop++;
+		} else {
+			frag_set_pending_idx(&skb_shinfo(skb)->frags[0],
+					     INVALID_PENDING_IDX);
+			memcpy(&queue->pending_tx_info[pending_idx].req, &txreq,
+			       sizeof(txreq));
+		}
+
+		queue->pending_cons++;
+
+		request_gop = xenvif_get_requests(queue, skb, txfrags, gop);
+		if (request_gop == NULL) {
+			kfree_skb(skb);
+			xenvif_tx_err(queue, &txreq, idx);
+			break;
+		}
+		gop = request_gop;
+
+		__skb_queue_tail(&queue->tx_queue, skb);
+
+		queue->tx.req_cons = idx;
+
+		if (((gop-queue->tx_map_ops) >= ARRAY_SIZE(queue->tx_map_ops)) ||
+		    (*copy_ops >= ARRAY_SIZE(queue->tx_copy_ops)))
+			break;
+	}
+
+	(*map_ops) = gop - queue->tx_map_ops;
+	return;
+}
+
+/* Consolidate skb with a frag_list into a brand new one with local pages on
+ * frags. Returns 0 or -ENOMEM if can't allocate new pages.
+ */
+static int xenvif_handle_frag_list(struct xenvif_queue *queue, struct sk_buff *skb)
+{
+	unsigned int offset = skb_headlen(skb);
+	skb_frag_t frags[MAX_SKB_FRAGS];
+	int i, f;
+	struct ubuf_info *uarg;
+	struct sk_buff *nskb = skb_shinfo(skb)->frag_list;
+
+	queue->stats.tx_zerocopy_sent += 2;
+	queue->stats.tx_frag_overflow++;
+
+	xenvif_fill_frags(queue, nskb);
+	/* Subtract frags size, we will correct it later */
+	skb->truesize -= skb->data_len;
+	skb->len += nskb->len;
+	skb->data_len += nskb->len;
+
+	/* create a brand new frags array and coalesce there */
+	for (i = 0; offset < skb->len; i++) {
+		struct page *page;
+		unsigned int len;
+
+		BUG_ON(i >= MAX_SKB_FRAGS);
+		page = alloc_page(GFP_ATOMIC);
+		if (!page) {
+			int j;
+			skb->truesize += skb->data_len;
+			for (j = 0; j < i; j++)
+				put_page(frags[j].page.p);
+			return -ENOMEM;
+		}
+
+		if (offset + PAGE_SIZE < skb->len)
+			len = PAGE_SIZE;
+		else
+			len = skb->len - offset;
+		if (skb_copy_bits(skb, offset, page_address(page), len))
+			BUG();
+
+		offset += len;
+		frags[i].page.p = page;
+		frags[i].page_offset = 0;
+		skb_frag_size_set(&frags[i], len);
+	}
+
+	/* Copied all the bits from the frag list -- free it. */
+	skb_frag_list_init(skb);
+	xenvif_skb_zerocopy_prepare(queue, nskb);
+	kfree_skb(nskb);
+
+	/* Release all the original (foreign) frags. */
+	for (f = 0; f < skb_shinfo(skb)->nr_frags; f++)
+		skb_frag_unref(skb, f);
+	uarg = skb_shinfo(skb)->destructor_arg;
+	/* increase inflight counter to offset decrement in callback */
+	atomic_inc(&queue->inflight_packets);
+	uarg->callback(uarg, true);
+	skb_shinfo(skb)->destructor_arg = NULL;
+
+	/* Fill the skb with the new (local) frags. */
+	memcpy(skb_shinfo(skb)->frags, frags, i * sizeof(skb_frag_t));
+	skb_shinfo(skb)->nr_frags = i;
+	skb->truesize += i * PAGE_SIZE;
+
+	return 0;
+}
+
+static int xenvif_tx_submit(struct xenvif_queue *queue)
+{
+	struct gnttab_map_grant_ref *gop_map = queue->tx_map_ops;
+	struct gnttab_copy *gop_copy = queue->tx_copy_ops;
+	struct sk_buff *skb;
+	int work_done = 0;
+
+	while ((skb = __skb_dequeue(&queue->tx_queue)) != NULL) {
+		struct xen_netif_tx_request *txp;
+		u16 pending_idx;
+		unsigned data_len;
+
+		pending_idx = XENVIF_TX_CB(skb)->pending_idx;
+		txp = &queue->pending_tx_info[pending_idx].req;
+
+		/* Check the remap error code. */
+		if (unlikely(xenvif_tx_check_gop(queue, skb, &gop_map, &gop_copy))) {
+			/* If there was an error, xenvif_tx_check_gop is
+			 * expected to release all the frags which were mapped,
+			 * so kfree_skb shouldn't do it again
+			 */
+			skb_shinfo(skb)->nr_frags = 0;
+			if (skb_has_frag_list(skb)) {
+				struct sk_buff *nskb =
+						skb_shinfo(skb)->frag_list;
+				skb_shinfo(nskb)->nr_frags = 0;
+			}
+			kfree_skb(skb);
+			continue;
+		}
+
+		data_len = skb->len;
+		callback_param(queue, pending_idx).ctx = NULL;
+		if (data_len < txp->size) {
+			/* Append the packet payload as a fragment. */
+			txp->offset += data_len;
+			txp->size -= data_len;
+		} else {
+			/* Schedule a response immediately. */
+			xenvif_idx_release(queue, pending_idx,
+					   XEN_NETIF_RSP_OKAY);
+		}
+
+		if (txp->flags & XEN_NETTXF_csum_blank)
+			skb->ip_summed = CHECKSUM_PARTIAL;
+		else if (txp->flags & XEN_NETTXF_data_validated)
+			skb->ip_summed = CHECKSUM_UNNECESSARY;
+
+		xenvif_fill_frags(queue, skb);
+
+		if (unlikely(skb_has_frag_list(skb))) {
+			if (xenvif_handle_frag_list(queue, skb)) {
+				if (net_ratelimit())
+					netdev_err(queue->vif->dev,
+						   "Not enough memory to consolidate frag_list!\n");
+				xenvif_skb_zerocopy_prepare(queue, skb);
+				kfree_skb(skb);
+				continue;
+			}
+		}
+
+		skb->dev      = queue->vif->dev;
+		skb->protocol = eth_type_trans(skb, skb->dev);
+		skb_reset_network_header(skb);
+
+		if (checksum_setup(queue, skb)) {
+			netdev_dbg(queue->vif->dev,
+				   "Can't setup checksum in net_tx_action\n");
+			/* We have to set this flag to trigger the callback */
+			if (skb_shinfo(skb)->destructor_arg)
+				xenvif_skb_zerocopy_prepare(queue, skb);
+			kfree_skb(skb);
+			continue;
+		}
+
+		skb_probe_transport_header(skb, 0);
+
+		/* If the packet is GSO then we will have just set up the
+		 * transport header offset in checksum_setup so it's now
+		 * straightforward to calculate gso_segs.
+		 */
+		if (skb_is_gso(skb)) {
+			int mss = skb_shinfo(skb)->gso_size;
+			int hdrlen = skb_transport_header(skb) -
+				skb_mac_header(skb) +
+				tcp_hdrlen(skb);
+
+			skb_shinfo(skb)->gso_segs =
+				DIV_ROUND_UP(skb->len - hdrlen, mss);
+		}
+
+		queue->stats.rx_bytes += skb->len;
+		queue->stats.rx_packets++;
+
+		work_done++;
+
+		/* Set this flag right before netif_receive_skb, otherwise
+		 * someone might think this packet already left netback, and
+		 * do a skb_copy_ubufs while we are still in control of the
+		 * skb. E.g. the __pskb_pull_tail earlier can do such thing.
+		 */
+		if (skb_shinfo(skb)->destructor_arg) {
+			xenvif_skb_zerocopy_prepare(queue, skb);
+			queue->stats.tx_zerocopy_sent++;
+		}
+
+		netif_receive_skb(skb);
+	}
+
+	return work_done;
+}
+
+void xenvif_zerocopy_callback(struct ubuf_info *ubuf, bool zerocopy_success)
+{
+	unsigned long flags;
+	pending_ring_idx_t index;
+	struct xenvif_queue *queue = ubuf_to_queue(ubuf);
+
+	/* This is the only place where we grab this lock, to protect callbacks
+	 * from each other.
+	 */
+	spin_lock_irqsave(&queue->callback_lock, flags);
+	do {
+		u16 pending_idx = ubuf->desc;
+		ubuf = (struct ubuf_info *) ubuf->ctx;
+		BUG_ON(queue->dealloc_prod - queue->dealloc_cons >=
+			MAX_PENDING_REQS);
+		index = pending_index(queue->dealloc_prod);
+		queue->dealloc_ring[index] = pending_idx;
+		/* Sync with xenvif_tx_dealloc_action:
+		 * insert idx then incr producer.
+		 */
+		smp_wmb();
+		queue->dealloc_prod++;
+	} while (ubuf);
+	wake_up(&queue->dealloc_wq);
+	spin_unlock_irqrestore(&queue->callback_lock, flags);
+
+	if (likely(zerocopy_success))
+		queue->stats.tx_zerocopy_success++;
+	else
+		queue->stats.tx_zerocopy_fail++;
+	xenvif_skb_zerocopy_complete(queue);
+}
+
+static inline void xenvif_tx_dealloc_action(struct xenvif_queue *queue)
+{
+	struct gnttab_unmap_grant_ref *gop;
+	pending_ring_idx_t dc, dp;
+	u16 pending_idx, pending_idx_release[MAX_PENDING_REQS];
+	unsigned int i = 0;
+
+	dc = queue->dealloc_cons;
+	gop = queue->tx_unmap_ops;
+
+	/* Free up any grants we have finished using */
+	do {
+		dp = queue->dealloc_prod;
+
+		/* Ensure we see all indices enqueued by all
+		 * xenvif_zerocopy_callback().
+		 */
+		smp_rmb();
+
+		while (dc != dp) {
+			BUG_ON(gop - queue->tx_unmap_ops > MAX_PENDING_REQS);
+			pending_idx =
+				queue->dealloc_ring[pending_index(dc++)];
+
+			pending_idx_release[gop-queue->tx_unmap_ops] =
+				pending_idx;
+			queue->pages_to_unmap[gop-queue->tx_unmap_ops] =
+				queue->mmap_pages[pending_idx];
+			gnttab_set_unmap_op(gop,
+					    idx_to_kaddr(queue, pending_idx),
+					    GNTMAP_host_map,
+					    queue->grant_tx_handle[pending_idx]);
+			xenvif_grant_handle_reset(queue, pending_idx);
+			++gop;
+		}
+
+	} while (dp != queue->dealloc_prod);
+
+	queue->dealloc_cons = dc;
+
+	if (gop - queue->tx_unmap_ops > 0) {
+		int ret;
+		ret = gnttab_unmap_refs(queue->tx_unmap_ops,
+					NULL,
+					queue->pages_to_unmap,
+					gop - queue->tx_unmap_ops);
+		if (ret) {
+			netdev_err(queue->vif->dev, "Unmap fail: nr_ops %tx ret %d\n",
+				   gop - queue->tx_unmap_ops, ret);
+			for (i = 0; i < gop - queue->tx_unmap_ops; ++i) {
+				if (gop[i].status != GNTST_okay)
+					netdev_err(queue->vif->dev,
+						   " host_addr: %llx handle: %x status: %d\n",
+						   gop[i].host_addr,
+						   gop[i].handle,
+						   gop[i].status);
+			}
+			BUG();
+		}
+	}
+
+	for (i = 0; i < gop - queue->tx_unmap_ops; ++i)
+		xenvif_idx_release(queue, pending_idx_release[i],
+				   XEN_NETIF_RSP_OKAY);
+}
+
+
+/* Called after netfront has transmitted */
+int xenvif_tx_action(struct xenvif_queue *queue, int budget)
+{
+	unsigned nr_mops, nr_cops = 0;
+	int work_done, ret;
+
+	if (unlikely(!tx_work_todo(queue)))
+		return 0;
+
+	xenvif_tx_build_gops(queue, budget, &nr_cops, &nr_mops);
+
+	if (nr_cops == 0)
+		return 0;
+
+	gnttab_batch_copy(queue->tx_copy_ops, nr_cops);
+	if (nr_mops != 0) {
+		ret = gnttab_map_refs(queue->tx_map_ops,
+				      NULL,
+				      queue->pages_to_map,
+				      nr_mops);
+		BUG_ON(ret);
+	}
+
+	work_done = xenvif_tx_submit(queue);
+
+	return work_done;
+}
+
+static void xenvif_idx_release(struct xenvif_queue *queue, u16 pending_idx,
+			       u8 status)
+{
+	struct pending_tx_info *pending_tx_info;
+	pending_ring_idx_t index;
+	unsigned long flags;
+
+	pending_tx_info = &queue->pending_tx_info[pending_idx];
+
+	spin_lock_irqsave(&queue->response_lock, flags);
+
+	make_tx_response(queue, &pending_tx_info->req, status);
+
+	/* Release the pending index before pusing the Tx response so
+	 * its available before a new Tx request is pushed by the
+	 * frontend.
+	 */
+	index = pending_index(queue->pending_prod++);
+	queue->pending_ring[index] = pending_idx;
+
+	push_tx_responses(queue);
+
+	spin_unlock_irqrestore(&queue->response_lock, flags);
+}
+
+
+static void make_tx_response(struct xenvif_queue *queue,
+			     struct xen_netif_tx_request *txp,
+			     s8       st)
+{
+	RING_IDX i = queue->tx.rsp_prod_pvt;
+	struct xen_netif_tx_response *resp;
+
+	resp = RING_GET_RESPONSE(&queue->tx, i);
+	resp->id     = txp->id;
+	resp->status = st;
+
+	if (txp->flags & XEN_NETTXF_extra_info)
+		RING_GET_RESPONSE(&queue->tx, ++i)->status = XEN_NETIF_RSP_NULL;
+
+	queue->tx.rsp_prod_pvt = ++i;
+}
+
+static void push_tx_responses(struct xenvif_queue *queue)
+{
+	int notify;
+
+	RING_PUSH_RESPONSES_AND_CHECK_NOTIFY(&queue->tx, notify);
+	if (notify)
+		notify_remote_via_irq(queue->tx_irq);
+}
+
+static struct xen_netif_rx_response *make_rx_response(struct xenvif_queue *queue,
+					     u16      id,
+					     s8       st,
+					     u16      offset,
+					     u16      size,
+					     u16      flags)
+{
+	RING_IDX i = queue->rx.rsp_prod_pvt;
+	struct xen_netif_rx_response *resp;
+
+	resp = RING_GET_RESPONSE(&queue->rx, i);
+	resp->offset     = offset;
+	resp->flags      = flags;
+	resp->id         = id;
+	resp->status     = (s16)size;
+	if (st < 0)
+		resp->status = (s16)st;
+
+	queue->rx.rsp_prod_pvt = ++i;
+
+	return resp;
+}
+
+void xenvif_idx_unmap(struct xenvif_queue *queue, u16 pending_idx)
+{
+	int ret;
+	struct gnttab_unmap_grant_ref tx_unmap_op;
+
+	gnttab_set_unmap_op(&tx_unmap_op,
+			    idx_to_kaddr(queue, pending_idx),
+			    GNTMAP_host_map,
+			    queue->grant_tx_handle[pending_idx]);
+	xenvif_grant_handle_reset(queue, pending_idx);
+
+	ret = gnttab_unmap_refs(&tx_unmap_op, NULL,
+				&queue->mmap_pages[pending_idx], 1);
+	if (ret) {
+		netdev_err(queue->vif->dev,
+			   "Unmap fail: ret: %d pending_idx: %d host_addr: %llx handle: %x status: %d\n",
+			   ret,
+			   pending_idx,
+			   tx_unmap_op.host_addr,
+			   tx_unmap_op.handle,
+			   tx_unmap_op.status);
+		BUG();
+	}
+}
+
+static inline int tx_work_todo(struct xenvif_queue *queue)
+{
+	if (likely(RING_HAS_UNCONSUMED_REQUESTS(&queue->tx)))
+		return 1;
+
+	return 0;
+}
+
+static inline bool tx_dealloc_work_todo(struct xenvif_queue *queue)
+{
+	return queue->dealloc_cons != queue->dealloc_prod;
+}
+
+void xenvif_unmap_frontend_rings(struct xenvif_queue *queue)
+{
+	if (queue->tx.sring)
+		xenbus_unmap_ring_vfree(xenvif_to_xenbus_device(queue->vif),
+					queue->tx.sring);
+	if (queue->rx.sring)
+		xenbus_unmap_ring_vfree(xenvif_to_xenbus_device(queue->vif),
+					queue->rx.sring);
+}
+
+int xenvif_map_frontend_rings(struct xenvif_queue *queue,
+			      grant_ref_t tx_ring_ref,
+			      grant_ref_t rx_ring_ref)
+{
+	void *addr;
+	struct xen_netif_tx_sring *txs;
+	struct xen_netif_rx_sring *rxs;
+
+	int err = -ENOMEM;
+
+	err = xenbus_map_ring_valloc(xenvif_to_xenbus_device(queue->vif),
+				     &tx_ring_ref, 1, &addr);
+	if (err)
+		goto err;
+
+	txs = (struct xen_netif_tx_sring *)addr;
+	BACK_RING_INIT(&queue->tx, txs, PAGE_SIZE);
+
+	err = xenbus_map_ring_valloc(xenvif_to_xenbus_device(queue->vif),
+				     &rx_ring_ref, 1, &addr);
+	if (err)
+		goto err;
+
+	rxs = (struct xen_netif_rx_sring *)addr;
+	BACK_RING_INIT(&queue->rx, rxs, PAGE_SIZE);
+
+	return 0;
+
+err:
+	xenvif_unmap_frontend_rings(queue);
+	return err;
+}
+
+static void xenvif_queue_carrier_off(struct xenvif_queue *queue)
+{
+	struct xenvif *vif = queue->vif;
+
+	queue->stalled = true;
+
+	/* At least one queue has stalled? Disable the carrier. */
+	spin_lock(&vif->lock);
+	if (vif->stalled_queues++ == 0) {
+		netdev_info(vif->dev, "Guest Rx stalled");
+		netif_carrier_off(vif->dev);
+	}
+	spin_unlock(&vif->lock);
+}
+
+static void xenvif_queue_carrier_on(struct xenvif_queue *queue)
+{
+	struct xenvif *vif = queue->vif;
+
+	queue->last_rx_time = jiffies; /* Reset Rx stall detection. */
+	queue->stalled = false;
+
+	/* All queues are ready? Enable the carrier. */
+	spin_lock(&vif->lock);
+	if (--vif->stalled_queues == 0) {
+		netdev_info(vif->dev, "Guest Rx ready");
+		netif_carrier_on(vif->dev);
+	}
+	spin_unlock(&vif->lock);
+}
+
+static bool xenvif_rx_queue_stalled(struct xenvif_queue *queue)
+{
+	RING_IDX prod, cons;
+
+	prod = queue->rx.sring->req_prod;
+	cons = queue->rx.req_cons;
+
+	return !queue->stalled
+		&& prod - cons < XEN_NETBK_RX_SLOTS_MAX
+		&& time_after(jiffies,
+			      queue->last_rx_time + queue->vif->stall_timeout);
+}
+
+static bool xenvif_rx_queue_ready(struct xenvif_queue *queue)
+{
+	RING_IDX prod, cons;
+
+	prod = queue->rx.sring->req_prod;
+	cons = queue->rx.req_cons;
+
+	return queue->stalled
+		&& prod - cons >= XEN_NETBK_RX_SLOTS_MAX;
+}
+
+static bool xenvif_have_rx_work(struct xenvif_queue *queue)
+{
+	return (!skb_queue_empty(&queue->rx_queue)
+		&& xenvif_rx_ring_slots_available(queue, XEN_NETBK_RX_SLOTS_MAX))
+		|| (queue->vif->stall_timeout &&
+		    (xenvif_rx_queue_stalled(queue)
+		     || xenvif_rx_queue_ready(queue)))
+		|| kthread_should_stop()
+		|| queue->vif->disabled;
+}
+
+static long xenvif_rx_queue_timeout(struct xenvif_queue *queue)
+{
+	struct sk_buff *skb;
+	long timeout;
+
+	skb = skb_peek(&queue->rx_queue);
+	if (!skb)
+		return MAX_SCHEDULE_TIMEOUT;
+
+	timeout = XENVIF_RX_CB(skb)->expires - jiffies;
+	return timeout < 0 ? 0 : timeout;
+}
+
+/* Wait until the guest Rx thread has work.
+ *
+ * The timeout needs to be adjusted based on the current head of the
+ * queue (and not just the head at the beginning).  In particular, if
+ * the queue is initially empty an infinite timeout is used and this
+ * needs to be reduced when a skb is queued.
+ *
+ * This cannot be done with wait_event_timeout() because it only
+ * calculates the timeout once.
+ */
+static void xenvif_wait_for_rx_work(struct xenvif_queue *queue)
+{
+	DEFINE_WAIT(wait);
+
+	if (xenvif_have_rx_work(queue))
+		return;
+
+	for (;;) {
+		long ret;
+
+		prepare_to_wait(&queue->wq, &wait, TASK_INTERRUPTIBLE);
+		if (xenvif_have_rx_work(queue))
+			break;
+		ret = schedule_timeout(xenvif_rx_queue_timeout(queue));
+		if (!ret)
+			break;
+	}
+	finish_wait(&queue->wq, &wait);
+}
+
+int xenvif_kthread_guest_rx(void *data)
+{
+	struct xenvif_queue *queue = data;
+	struct xenvif *vif = queue->vif;
+
+	if (!vif->stall_timeout)
+		xenvif_queue_carrier_on(queue);
+
+	for (;;) {
+		xenvif_wait_for_rx_work(queue);
+
+		if (kthread_should_stop())
+			break;
+
+		/* This frontend is found to be rogue, disable it in
+		 * kthread context. Currently this is only set when
+		 * netback finds out frontend sends malformed packet,
+		 * but we cannot disable the interface in softirq
+		 * context so we defer it here, if this thread is
+		 * associated with queue 0.
+		 */
+		if (unlikely(vif->disabled && queue->id == 0)) {
+			xenvif_carrier_off(vif);
+			break;
+		}
+
+		if (!skb_queue_empty(&queue->rx_queue))
+			xenvif_rx_action(queue);
+
+		/* If the guest hasn't provided any Rx slots for a
+		 * while it's probably not responsive, drop the
+		 * carrier so packets are dropped earlier.
+		 */
+		if (vif->stall_timeout) {
+			if (xenvif_rx_queue_stalled(queue))
+				xenvif_queue_carrier_off(queue);
+			else if (xenvif_rx_queue_ready(queue))
+				xenvif_queue_carrier_on(queue);
+		}
+
+		/* Queued packets may have foreign pages from other
+		 * domains.  These cannot be queued indefinitely as
+		 * this would starve guests of grant refs and transmit
+		 * slots.
+		 */
+		xenvif_rx_queue_drop_expired(queue);
+
+		xenvif_rx_queue_maybe_wake(queue);
+
+		cond_resched();
+	}
+
+	/* Bin any remaining skbs */
+	xenvif_rx_queue_purge(queue);
+
+	return 0;
+}
+
+static bool xenvif_dealloc_kthread_should_stop(struct xenvif_queue *queue)
+{
+	/* Dealloc thread must remain running until all inflight
+	 * packets complete.
+	 */
+	return kthread_should_stop() &&
+		!atomic_read(&queue->inflight_packets);
+}
+
+int xenvif_dealloc_kthread(void *data)
+{
+	struct xenvif_queue *queue = data;
+
+	for (;;) {
+		wait_event_interruptible(queue->dealloc_wq,
+					 tx_dealloc_work_todo(queue) ||
+					 xenvif_dealloc_kthread_should_stop(queue));
+		if (xenvif_dealloc_kthread_should_stop(queue))
+			break;
+
+		xenvif_tx_dealloc_action(queue);
+		cond_resched();
+	}
+
+	/* Unmap anything remaining*/
+	if (tx_dealloc_work_todo(queue))
+		xenvif_tx_dealloc_action(queue);
+
+	return 0;
+}
+
+static int __init netback_init(void)
+{
+	int rc = 0;
+
+	if (!xen_domain())
+		return -ENODEV;
+
+	/* Allow as many queues as there are CPUs, by default */
+	xenvif_max_queues = num_online_cpus();
+
+	if (fatal_skb_slots < XEN_NETBK_LEGACY_SLOTS_MAX) {
+		pr_info("fatal_skb_slots too small (%d), bump it to XEN_NETBK_LEGACY_SLOTS_MAX (%d)\n",
+			fatal_skb_slots, XEN_NETBK_LEGACY_SLOTS_MAX);
+		fatal_skb_slots = XEN_NETBK_LEGACY_SLOTS_MAX;
+	}
+
+	rc = xenvif_xenbus_init();
+	if (rc)
+		goto failed_init;
+
+#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;
+
+failed_init:
+	return rc;
+}
+
+module_init(netback_init);
+
+static void __exit netback_fini(void)
+{
+#ifdef CONFIG_DEBUG_FS
+	if (!IS_ERR_OR_NULL(xen_netback_dbg_root))
+		debugfs_remove_recursive(xen_netback_dbg_root);
+#endif /* CONFIG_DEBUG_FS */
+	xenvif_xenbus_fini();
+}
+module_exit(netback_fini);
+
+MODULE_LICENSE("Dual BSD/GPL");
+MODULE_ALIAS("xen-backend:vif");