diff --git a/drivers/net/xen-netback/netback.c b/drivers/net/xen-netback/netback.c
new file mode 100644
index 0000000..0e4851b
--- /dev/null
+++ b/drivers/net/xen-netback/netback.c
@@ -0,0 +1,1745 @@
+/*
+ * 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 <net/tcp.h>
+
+#include <xen/events.h>
+#include <xen/interface/memory.h>
+
+#include <asm/xen/hypercall.h>
+#include <asm/xen/page.h>
+
+struct pending_tx_info {
+	struct xen_netif_tx_request req;
+	struct xenvif *vif;
+};
+typedef unsigned int pending_ring_idx_t;
+
+struct netbk_rx_meta {
+	int id;
+	int size;
+	int gso_size;
+};
+
+#define MAX_PENDING_REQS 256
+
+#define MAX_BUFFER_OFFSET PAGE_SIZE
+
+/* extra field used in struct page */
+union page_ext {
+	struct {
+#if BITS_PER_LONG < 64
+#define IDX_WIDTH   8
+#define GROUP_WIDTH (BITS_PER_LONG - IDX_WIDTH)
+		unsigned int group:GROUP_WIDTH;
+		unsigned int idx:IDX_WIDTH;
+#else
+		unsigned int group, idx;
+#endif
+	} e;
+	void *mapping;
+};
+
+struct xen_netbk {
+	wait_queue_head_t wq;
+	struct task_struct *task;
+
+	struct sk_buff_head rx_queue;
+	struct sk_buff_head tx_queue;
+
+	struct timer_list net_timer;
+
+	struct page *mmap_pages[MAX_PENDING_REQS];
+
+	pending_ring_idx_t pending_prod;
+	pending_ring_idx_t pending_cons;
+	struct list_head net_schedule_list;
+
+	/* Protect the net_schedule_list in netif. */
+	spinlock_t net_schedule_list_lock;
+
+	atomic_t netfront_count;
+
+	struct pending_tx_info pending_tx_info[MAX_PENDING_REQS];
+	struct gnttab_copy tx_copy_ops[MAX_PENDING_REQS];
+
+	u16 pending_ring[MAX_PENDING_REQS];
+
+	/*
+	 * Given MAX_BUFFER_OFFSET of 4096 the worst case is that each
+	 * head/fragment page uses 2 copy operations because it
+	 * straddles two buffers in the frontend.
+	 */
+	struct gnttab_copy grant_copy_op[2*XEN_NETIF_RX_RING_SIZE];
+	struct netbk_rx_meta meta[2*XEN_NETIF_RX_RING_SIZE];
+};
+
+static struct xen_netbk *xen_netbk;
+static int xen_netbk_group_nr;
+
+void xen_netbk_add_xenvif(struct xenvif *vif)
+{
+	int i;
+	int min_netfront_count;
+	int min_group = 0;
+	struct xen_netbk *netbk;
+
+	min_netfront_count = atomic_read(&xen_netbk[0].netfront_count);
+	for (i = 0; i < xen_netbk_group_nr; i++) {
+		int netfront_count = atomic_read(&xen_netbk[i].netfront_count);
+		if (netfront_count < min_netfront_count) {
+			min_group = i;
+			min_netfront_count = netfront_count;
+		}
+	}
+
+	netbk = &xen_netbk[min_group];
+
+	vif->netbk = netbk;
+	atomic_inc(&netbk->netfront_count);
+}
+
+void xen_netbk_remove_xenvif(struct xenvif *vif)
+{
+	struct xen_netbk *netbk = vif->netbk;
+	vif->netbk = NULL;
+	atomic_dec(&netbk->netfront_count);
+}
+
+static void xen_netbk_idx_release(struct xen_netbk *netbk, u16 pending_idx);
+static void make_tx_response(struct xenvif *vif,
+			     struct xen_netif_tx_request *txp,
+			     s8       st);
+static struct xen_netif_rx_response *make_rx_response(struct xenvif *vif,
+					     u16      id,
+					     s8       st,
+					     u16      offset,
+					     u16      size,
+					     u16      flags);
+
+static inline unsigned long idx_to_pfn(struct xen_netbk *netbk,
+				       unsigned int idx)
+{
+	return page_to_pfn(netbk->mmap_pages[idx]);
+}
+
+static inline unsigned long idx_to_kaddr(struct xen_netbk *netbk,
+					 unsigned int idx)
+{
+	return (unsigned long)pfn_to_kaddr(idx_to_pfn(netbk, idx));
+}
+
+/* extra field used in struct page */
+static inline void set_page_ext(struct page *pg, struct xen_netbk *netbk,
+				unsigned int idx)
+{
+	unsigned int group = netbk - xen_netbk;
+	union page_ext ext = { .e = { .group = group + 1, .idx = idx } };
+
+	BUILD_BUG_ON(sizeof(ext) > sizeof(ext.mapping));
+	pg->mapping = ext.mapping;
+}
+
+static int get_page_ext(struct page *pg,
+			unsigned int *pgroup, unsigned int *pidx)
+{
+	union page_ext ext = { .mapping = pg->mapping };
+	struct xen_netbk *netbk;
+	unsigned int group, idx;
+
+	group = ext.e.group - 1;
+
+	if (group < 0 || group >= xen_netbk_group_nr)
+		return 0;
+
+	netbk = &xen_netbk[group];
+
+	idx = ext.e.idx;
+
+	if ((idx < 0) || (idx >= MAX_PENDING_REQS))
+		return 0;
+
+	if (netbk->mmap_pages[idx] != pg)
+		return 0;
+
+	*pgroup = group;
+	*pidx = idx;
+
+	return 1;
+}
+
+/*
+ * This is the amount of packet we copy rather than map, so that the
+ * guest can't fiddle with the contents of the headers while we do
+ * packet processing on them (netfilter, routing, etc).
+ */
+#define PKT_PROT_LEN    (ETH_HLEN + \
+			 VLAN_HLEN + \
+			 sizeof(struct iphdr) + MAX_IPOPTLEN + \
+			 sizeof(struct tcphdr) + MAX_TCP_OPTION_SPACE)
+
+static inline pending_ring_idx_t pending_index(unsigned i)
+{
+	return i & (MAX_PENDING_REQS-1);
+}
+
+static inline pending_ring_idx_t nr_pending_reqs(struct xen_netbk *netbk)
+{
+	return MAX_PENDING_REQS -
+		netbk->pending_prod + netbk->pending_cons;
+}
+
+static void xen_netbk_kick_thread(struct xen_netbk *netbk)
+{
+	wake_up(&netbk->wq);
+}
+
+static int max_required_rx_slots(struct xenvif *vif)
+{
+	int max = DIV_ROUND_UP(vif->dev->mtu, PAGE_SIZE);
+
+	if (vif->can_sg || vif->gso || vif->gso_prefix)
+		max += MAX_SKB_FRAGS + 1; /* extra_info + frags */
+
+	return max;
+}
+
+int xen_netbk_rx_ring_full(struct xenvif *vif)
+{
+	RING_IDX peek   = vif->rx_req_cons_peek;
+	RING_IDX needed = max_required_rx_slots(vif);
+
+	return ((vif->rx.sring->req_prod - peek) < needed) ||
+	       ((vif->rx.rsp_prod_pvt + XEN_NETIF_RX_RING_SIZE - peek) < needed);
+}
+
+int xen_netbk_must_stop_queue(struct xenvif *vif)
+{
+	if (!xen_netbk_rx_ring_full(vif))
+		return 0;
+
+	vif->rx.sring->req_event = vif->rx_req_cons_peek +
+		max_required_rx_slots(vif);
+	mb(); /* request notification /then/ check the queue */
+
+	return xen_netbk_rx_ring_full(vif);
+}
+
+/*
+ * Returns true if we should start a new receive buffer instead of
+ * adding 'size' bytes to a buffer which currently contains 'offset'
+ * bytes.
+ */
+static bool start_new_rx_buffer(int offset, unsigned long size, int head)
+{
+	/* simple case: we have completely filled the current buffer. */
+	if (offset == MAX_BUFFER_OFFSET)
+		return true;
+
+	/*
+	 * complex case: start a fresh buffer if the current frag
+	 * would overflow the current buffer but only if:
+	 *     (i)   this frag would fit completely in the next buffer
+	 * and (ii)  there is already some data in the current buffer
+	 * and (iii) this is not the head buffer.
+	 *
+	 * Where:
+	 * - (i) stops us splitting a frag into two copies
+	 *   unless the frag is too large for a single buffer.
+	 * - (ii) stops us from leaving a buffer pointlessly empty.
+	 * - (iii) stops us leaving the first buffer
+	 *   empty. Strictly speaking this is already covered
+	 *   by (ii) but is explicitly checked because
+	 *   netfront relies on the first buffer being
+	 *   non-empty and can crash otherwise.
+	 *
+	 * This means we will effectively linearise small
+	 * frags but do not needlessly split large buffers
+	 * into multiple copies tend to give large frags their
+	 * own buffers as before.
+	 */
+	if ((offset + size > MAX_BUFFER_OFFSET) &&
+	    (size <= MAX_BUFFER_OFFSET) && offset && !head)
+		return true;
+
+	return false;
+}
+
+/*
+ * Figure out how many ring slots we're going to need to send @skb to
+ * the guest. This function is essentially a dry run of
+ * netbk_gop_frag_copy.
+ */
+unsigned int xen_netbk_count_skb_slots(struct xenvif *vif, struct sk_buff *skb)
+{
+	unsigned int count;
+	int i, copy_off;
+
+	count = DIV_ROUND_UP(
+			offset_in_page(skb->data)+skb_headlen(skb), PAGE_SIZE);
+
+	copy_off = skb_headlen(skb) % PAGE_SIZE;
+
+	if (skb_shinfo(skb)->gso_size)
+		count++;
+
+	for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
+		unsigned long size = skb_shinfo(skb)->frags[i].size;
+		unsigned long bytes;
+		while (size > 0) {
+			BUG_ON(copy_off > MAX_BUFFER_OFFSET);
+
+			if (start_new_rx_buffer(copy_off, size, 0)) {
+				count++;
+				copy_off = 0;
+			}
+
+			bytes = size;
+			if (copy_off + bytes > MAX_BUFFER_OFFSET)
+				bytes = MAX_BUFFER_OFFSET - copy_off;
+
+			copy_off += bytes;
+			size -= bytes;
+		}
+	}
+	return count;
+}
+
+struct netrx_pending_operations {
+	unsigned copy_prod, copy_cons;
+	unsigned meta_prod, meta_cons;
+	struct gnttab_copy *copy;
+	struct netbk_rx_meta *meta;
+	int copy_off;
+	grant_ref_t copy_gref;
+};
+
+static struct netbk_rx_meta *get_next_rx_buffer(struct xenvif *vif,
+						struct netrx_pending_operations *npo)
+{
+	struct netbk_rx_meta *meta;
+	struct xen_netif_rx_request *req;
+
+	req = RING_GET_REQUEST(&vif->rx, vif->rx.req_cons++);
+
+	meta = npo->meta + npo->meta_prod++;
+	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 netbk_gop_frag_copy(struct xenvif *vif, 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 netbk_rx_meta *meta;
+	/*
+	 * These variables a used iff get_page_ext returns true,
+	 * in which case they are guaranteed to be initialized.
+	 */
+	unsigned int uninitialized_var(group), uninitialized_var(idx);
+	int foreign = get_page_ext(page, &group, &idx);
+	unsigned long bytes;
+
+	/* Data must not cross a page boundary. */
+	BUG_ON(size + offset > PAGE_SIZE);
+
+	meta = npo->meta + npo->meta_prod - 1;
+
+	while (size > 0) {
+		BUG_ON(npo->copy_off > MAX_BUFFER_OFFSET);
+
+		if (start_new_rx_buffer(npo->copy_off, size, *head)) {
+			/*
+			 * Netfront requires there to be some data in the head
+			 * buffer.
+			 */
+			BUG_ON(*head);
+
+			meta = get_next_rx_buffer(vif, npo);
+		}
+
+		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;
+		if (foreign) {
+			struct xen_netbk *netbk = &xen_netbk[group];
+			struct pending_tx_info *src_pend;
+
+			src_pend = &netbk->pending_tx_info[idx];
+
+			copy_gop->source.domid = src_pend->vif->domid;
+			copy_gop->source.u.ref = src_pend->req.gref;
+			copy_gop->flags |= GNTCOPY_source_gref;
+		} else {
+			void *vaddr = page_address(page);
+			copy_gop->source.domid = DOMID_SELF;
+			copy_gop->source.u.gmfn = virt_to_mfn(vaddr);
+		}
+		copy_gop->source.offset = offset;
+		copy_gop->dest.domid = vif->domid;
+
+		copy_gop->dest.offset = npo->copy_off;
+		copy_gop->dest.u.ref = npo->copy_gref;
+		copy_gop->len = bytes;
+
+		npo->copy_off += bytes;
+		meta->size += bytes;
+
+		offset += bytes;
+		size -= bytes;
+
+		/* Leave a gap for the GSO descriptor. */
+		if (*head && skb_shinfo(skb)->gso_size && !vif->gso_prefix)
+			vif->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 netbk_gop_skb(struct sk_buff *skb,
+			 struct netrx_pending_operations *npo)
+{
+	struct xenvif *vif = netdev_priv(skb->dev);
+	int nr_frags = skb_shinfo(skb)->nr_frags;
+	int i;
+	struct xen_netif_rx_request *req;
+	struct netbk_rx_meta *meta;
+	unsigned char *data;
+	int head = 1;
+	int old_meta_prod;
+
+	old_meta_prod = npo->meta_prod;
+
+	/* Set up a GSO prefix descriptor, if necessary */
+	if (skb_shinfo(skb)->gso_size && vif->gso_prefix) {
+		req = RING_GET_REQUEST(&vif->rx, vif->rx.req_cons++);
+		meta = npo->meta + npo->meta_prod++;
+		meta->gso_size = skb_shinfo(skb)->gso_size;
+		meta->size = 0;
+		meta->id = req->id;
+	}
+
+	req = RING_GET_REQUEST(&vif->rx, vif->rx.req_cons++);
+	meta = npo->meta + npo->meta_prod++;
+
+	if (!vif->gso_prefix)
+		meta->gso_size = skb_shinfo(skb)->gso_size;
+	else
+		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;
+
+		netbk_gop_frag_copy(vif, skb, npo,
+				    virt_to_page(data), len, offset, &head);
+		data += len;
+	}
+
+	for (i = 0; i < nr_frags; i++) {
+		netbk_gop_frag_copy(vif, skb, npo,
+				    skb_shinfo(skb)->frags[i].page,
+				    skb_shinfo(skb)->frags[i].size,
+				    skb_shinfo(skb)->frags[i].page_offset,
+				    &head);
+	}
+
+	return npo->meta_prod - old_meta_prod;
+}
+
+/*
+ * This is a twin to netbk_gop_skb.  Assume that netbk_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 netbk_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 netbk_add_frag_responses(struct xenvif *vif, int status,
+				     struct netbk_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(vif, meta[i].id, status, offset,
+				 meta[i].size, flags);
+	}
+}
+
+struct skb_cb_overlay {
+	int meta_slots_used;
+};
+
+static void xen_netbk_rx_action(struct xen_netbk *netbk)
+{
+	struct xenvif *vif = NULL, *tmp;
+	s8 status;
+	u16 irq, flags;
+	struct xen_netif_rx_response *resp;
+	struct sk_buff_head rxq;
+	struct sk_buff *skb;
+	LIST_HEAD(notify);
+	int ret;
+	int nr_frags;
+	int count;
+	unsigned long offset;
+	struct skb_cb_overlay *sco;
+
+	struct netrx_pending_operations npo = {
+		.copy  = netbk->grant_copy_op,
+		.meta  = netbk->meta,
+	};
+
+	skb_queue_head_init(&rxq);
+
+	count = 0;
+
+	while ((skb = skb_dequeue(&netbk->rx_queue)) != NULL) {
+		vif = netdev_priv(skb->dev);
+		nr_frags = skb_shinfo(skb)->nr_frags;
+
+		sco = (struct skb_cb_overlay *)skb->cb;
+		sco->meta_slots_used = netbk_gop_skb(skb, &npo);
+
+		count += nr_frags + 1;
+
+		__skb_queue_tail(&rxq, skb);
+
+		/* Filled the batch queue? */
+		if (count + MAX_SKB_FRAGS >= XEN_NETIF_RX_RING_SIZE)
+			break;
+	}
+
+	BUG_ON(npo.meta_prod > ARRAY_SIZE(netbk->meta));
+
+	if (!npo.copy_prod)
+		return;
+
+	BUG_ON(npo.copy_prod > ARRAY_SIZE(netbk->grant_copy_op));
+	ret = HYPERVISOR_grant_table_op(GNTTABOP_copy, &netbk->grant_copy_op,
+					npo.copy_prod);
+	BUG_ON(ret != 0);
+
+	while ((skb = __skb_dequeue(&rxq)) != NULL) {
+		sco = (struct skb_cb_overlay *)skb->cb;
+
+		vif = netdev_priv(skb->dev);
+
+		if (netbk->meta[npo.meta_cons].gso_size && vif->gso_prefix) {
+			resp = RING_GET_RESPONSE(&vif->rx,
+						vif->rx.rsp_prod_pvt++);
+
+			resp->flags = XEN_NETRXF_gso_prefix | XEN_NETRXF_more_data;
+
+			resp->offset = netbk->meta[npo.meta_cons].gso_size;
+			resp->id = netbk->meta[npo.meta_cons].id;
+			resp->status = sco->meta_slots_used;
+
+			npo.meta_cons++;
+			sco->meta_slots_used--;
+		}
+
+
+		vif->dev->stats.tx_bytes += skb->len;
+		vif->dev->stats.tx_packets++;
+
+		status = netbk_check_gop(vif, sco->meta_slots_used, &npo);
+
+		if (sco->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(vif, netbk->meta[npo.meta_cons].id,
+					status, offset,
+					netbk->meta[npo.meta_cons].size,
+					flags);
+
+		if (netbk->meta[npo.meta_cons].gso_size && !vif->gso_prefix) {
+			struct xen_netif_extra_info *gso =
+				(struct xen_netif_extra_info *)
+				RING_GET_RESPONSE(&vif->rx,
+						  vif->rx.rsp_prod_pvt++);
+
+			resp->flags |= XEN_NETRXF_extra_info;
+
+			gso->u.gso.size = netbk->meta[npo.meta_cons].gso_size;
+			gso->u.gso.type = XEN_NETIF_GSO_TYPE_TCPV4;
+			gso->u.gso.pad = 0;
+			gso->u.gso.features = 0;
+
+			gso->type = XEN_NETIF_EXTRA_TYPE_GSO;
+			gso->flags = 0;
+		}
+
+		netbk_add_frag_responses(vif, status,
+					 netbk->meta + npo.meta_cons + 1,
+					 sco->meta_slots_used);
+
+		RING_PUSH_RESPONSES_AND_CHECK_NOTIFY(&vif->rx, ret);
+		irq = vif->irq;
+		if (ret && list_empty(&vif->notify_list))
+			list_add_tail(&vif->notify_list, &notify);
+
+		xenvif_notify_tx_completion(vif);
+
+		xenvif_put(vif);
+		npo.meta_cons += sco->meta_slots_used;
+		dev_kfree_skb(skb);
+	}
+
+	list_for_each_entry_safe(vif, tmp, &notify, notify_list) {
+		notify_remote_via_irq(vif->irq);
+		list_del_init(&vif->notify_list);
+	}
+
+	/* More work to do? */
+	if (!skb_queue_empty(&netbk->rx_queue) &&
+			!timer_pending(&netbk->net_timer))
+		xen_netbk_kick_thread(netbk);
+}
+
+void xen_netbk_queue_tx_skb(struct xenvif *vif, struct sk_buff *skb)
+{
+	struct xen_netbk *netbk = vif->netbk;
+
+	skb_queue_tail(&netbk->rx_queue, skb);
+
+	xen_netbk_kick_thread(netbk);
+}
+
+static void xen_netbk_alarm(unsigned long data)
+{
+	struct xen_netbk *netbk = (struct xen_netbk *)data;
+	xen_netbk_kick_thread(netbk);
+}
+
+static int __on_net_schedule_list(struct xenvif *vif)
+{
+	return !list_empty(&vif->schedule_list);
+}
+
+/* Must be called with net_schedule_list_lock held */
+static void remove_from_net_schedule_list(struct xenvif *vif)
+{
+	if (likely(__on_net_schedule_list(vif))) {
+		list_del_init(&vif->schedule_list);
+		xenvif_put(vif);
+	}
+}
+
+static struct xenvif *poll_net_schedule_list(struct xen_netbk *netbk)
+{
+	struct xenvif *vif = NULL;
+
+	spin_lock_irq(&netbk->net_schedule_list_lock);
+	if (list_empty(&netbk->net_schedule_list))
+		goto out;
+
+	vif = list_first_entry(&netbk->net_schedule_list,
+			       struct xenvif, schedule_list);
+	if (!vif)
+		goto out;
+
+	xenvif_get(vif);
+
+	remove_from_net_schedule_list(vif);
+out:
+	spin_unlock_irq(&netbk->net_schedule_list_lock);
+	return vif;
+}
+
+void xen_netbk_schedule_xenvif(struct xenvif *vif)
+{
+	unsigned long flags;
+	struct xen_netbk *netbk = vif->netbk;
+
+	if (__on_net_schedule_list(vif))
+		goto kick;
+
+	spin_lock_irqsave(&netbk->net_schedule_list_lock, flags);
+	if (!__on_net_schedule_list(vif) &&
+	    likely(xenvif_schedulable(vif))) {
+		list_add_tail(&vif->schedule_list, &netbk->net_schedule_list);
+		xenvif_get(vif);
+	}
+	spin_unlock_irqrestore(&netbk->net_schedule_list_lock, flags);
+
+kick:
+	smp_mb();
+	if ((nr_pending_reqs(netbk) < (MAX_PENDING_REQS/2)) &&
+	    !list_empty(&netbk->net_schedule_list))
+		xen_netbk_kick_thread(netbk);
+}
+
+void xen_netbk_deschedule_xenvif(struct xenvif *vif)
+{
+	struct xen_netbk *netbk = vif->netbk;
+	spin_lock_irq(&netbk->net_schedule_list_lock);
+	remove_from_net_schedule_list(vif);
+	spin_unlock_irq(&netbk->net_schedule_list_lock);
+}
+
+void xen_netbk_check_rx_xenvif(struct xenvif *vif)
+{
+	int more_to_do;
+
+	RING_FINAL_CHECK_FOR_REQUESTS(&vif->tx, more_to_do);
+
+	if (more_to_do)
+		xen_netbk_schedule_xenvif(vif);
+}
+
+static void tx_add_credit(struct xenvif *vif)
+{
+	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(&vif->tx, vif->tx.req_cons)->size;
+	max_burst = min(max_burst, 131072UL);
+	max_burst = max(max_burst, vif->credit_bytes);
+
+	/* Take care that adding a new chunk of credit doesn't wrap to zero. */
+	max_credit = vif->remaining_credit + vif->credit_bytes;
+	if (max_credit < vif->remaining_credit)
+		max_credit = ULONG_MAX; /* wrapped: clamp to ULONG_MAX */
+
+	vif->remaining_credit = min(max_credit, max_burst);
+}
+
+static void tx_credit_callback(unsigned long data)
+{
+	struct xenvif *vif = (struct xenvif *)data;
+	tx_add_credit(vif);
+	xen_netbk_check_rx_xenvif(vif);
+}
+
+static void netbk_tx_err(struct xenvif *vif,
+			 struct xen_netif_tx_request *txp, RING_IDX end)
+{
+	RING_IDX cons = vif->tx.req_cons;
+
+	do {
+		make_tx_response(vif, txp, XEN_NETIF_RSP_ERROR);
+		if (cons >= end)
+			break;
+		txp = RING_GET_REQUEST(&vif->tx, cons++);
+	} while (1);
+	vif->tx.req_cons = cons;
+	xen_netbk_check_rx_xenvif(vif);
+	xenvif_put(vif);
+}
+
+static int netbk_count_requests(struct xenvif *vif,
+				struct xen_netif_tx_request *first,
+				struct xen_netif_tx_request *txp,
+				int work_to_do)
+{
+	RING_IDX cons = vif->tx.req_cons;
+	int frags = 0;
+
+	if (!(first->flags & XEN_NETTXF_more_data))
+		return 0;
+
+	do {
+		if (frags >= work_to_do) {
+			netdev_dbg(vif->dev, "Need more frags\n");
+			return -frags;
+		}
+
+		if (unlikely(frags >= MAX_SKB_FRAGS)) {
+			netdev_dbg(vif->dev, "Too many frags\n");
+			return -frags;
+		}
+
+		memcpy(txp, RING_GET_REQUEST(&vif->tx, cons + frags),
+		       sizeof(*txp));
+		if (txp->size > first->size) {
+			netdev_dbg(vif->dev, "Frags galore\n");
+			return -frags;
+		}
+
+		first->size -= txp->size;
+		frags++;
+
+		if (unlikely((txp->offset + txp->size) > PAGE_SIZE)) {
+			netdev_dbg(vif->dev, "txp->offset: %x, size: %u\n",
+				 txp->offset, txp->size);
+			return -frags;
+		}
+	} while ((txp++)->flags & XEN_NETTXF_more_data);
+	return frags;
+}
+
+static struct page *xen_netbk_alloc_page(struct xen_netbk *netbk,
+					 struct sk_buff *skb,
+					 unsigned long pending_idx)
+{
+	struct page *page;
+	page = alloc_page(GFP_KERNEL|__GFP_COLD);
+	if (!page)
+		return NULL;
+	set_page_ext(page, netbk, pending_idx);
+	netbk->mmap_pages[pending_idx] = page;
+	return page;
+}
+
+static struct gnttab_copy *xen_netbk_get_requests(struct xen_netbk *netbk,
+						  struct xenvif *vif,
+						  struct sk_buff *skb,
+						  struct xen_netif_tx_request *txp,
+						  struct gnttab_copy *gop)
+{
+	struct skb_shared_info *shinfo = skb_shinfo(skb);
+	skb_frag_t *frags = shinfo->frags;
+	unsigned long pending_idx = *((u16 *)skb->data);
+	int i, start;
+
+	/* Skip first skb fragment if it is on same page as header fragment. */
+	start = ((unsigned long)shinfo->frags[0].page == pending_idx);
+
+	for (i = start; i < shinfo->nr_frags; i++, txp++) {
+		struct page *page;
+		pending_ring_idx_t index;
+		struct pending_tx_info *pending_tx_info =
+			netbk->pending_tx_info;
+
+		index = pending_index(netbk->pending_cons++);
+		pending_idx = netbk->pending_ring[index];
+		page = xen_netbk_alloc_page(netbk, skb, pending_idx);
+		if (!page)
+			return NULL;
+
+		netbk->mmap_pages[pending_idx] = page;
+
+		gop->source.u.ref = txp->gref;
+		gop->source.domid = vif->domid;
+		gop->source.offset = txp->offset;
+
+		gop->dest.u.gmfn = virt_to_mfn(page_address(page));
+		gop->dest.domid = DOMID_SELF;
+		gop->dest.offset = txp->offset;
+
+		gop->len = txp->size;
+		gop->flags = GNTCOPY_source_gref;
+
+		gop++;
+
+		memcpy(&pending_tx_info[pending_idx].req, txp, sizeof(*txp));
+		xenvif_get(vif);
+		pending_tx_info[pending_idx].vif = vif;
+		frags[i].page = (void *)pending_idx;
+	}
+
+	return gop;
+}
+
+static int xen_netbk_tx_check_gop(struct xen_netbk *netbk,
+				  struct sk_buff *skb,
+				  struct gnttab_copy **gopp)
+{
+	struct gnttab_copy *gop = *gopp;
+	int pending_idx = *((u16 *)skb->data);
+	struct pending_tx_info *pending_tx_info = netbk->pending_tx_info;
+	struct xenvif *vif = pending_tx_info[pending_idx].vif;
+	struct xen_netif_tx_request *txp;
+	struct skb_shared_info *shinfo = skb_shinfo(skb);
+	int nr_frags = shinfo->nr_frags;
+	int i, err, start;
+
+	/* Check status of header. */
+	err = gop->status;
+	if (unlikely(err)) {
+		pending_ring_idx_t index;
+		index = pending_index(netbk->pending_prod++);
+		txp = &pending_tx_info[pending_idx].req;
+		make_tx_response(vif, txp, XEN_NETIF_RSP_ERROR);
+		netbk->pending_ring[index] = pending_idx;
+		xenvif_put(vif);
+	}
+
+	/* Skip first skb fragment if it is on same page as header fragment. */
+	start = ((unsigned long)shinfo->frags[0].page == pending_idx);
+
+	for (i = start; i < nr_frags; i++) {
+		int j, newerr;
+		pending_ring_idx_t index;
+
+		pending_idx = (unsigned long)shinfo->frags[i].page;
+
+		/* Check error status: if okay then remember grant handle. */
+		newerr = (++gop)->status;
+		if (likely(!newerr)) {
+			/* Had a previous error? Invalidate this fragment. */
+			if (unlikely(err))
+				xen_netbk_idx_release(netbk, pending_idx);
+			continue;
+		}
+
+		/* Error on this fragment: respond to client with an error. */
+		txp = &netbk->pending_tx_info[pending_idx].req;
+		make_tx_response(vif, txp, XEN_NETIF_RSP_ERROR);
+		index = pending_index(netbk->pending_prod++);
+		netbk->pending_ring[index] = pending_idx;
+		xenvif_put(vif);
+
+		/* Not the first error? Preceding frags already invalidated. */
+		if (err)
+			continue;
+
+		/* First error: invalidate header and preceding fragments. */
+		pending_idx = *((u16 *)skb->data);
+		xen_netbk_idx_release(netbk, pending_idx);
+		for (j = start; j < i; j++) {
+			pending_idx = (unsigned long)shinfo->frags[i].page;
+			xen_netbk_idx_release(netbk, pending_idx);
+		}
+
+		/* Remember the error: invalidate all subsequent fragments. */
+		err = newerr;
+	}
+
+	*gopp = gop + 1;
+	return err;
+}
+
+static void xen_netbk_fill_frags(struct xen_netbk *netbk, struct sk_buff *skb)
+{
+	struct skb_shared_info *shinfo = skb_shinfo(skb);
+	int nr_frags = shinfo->nr_frags;
+	int i;
+
+	for (i = 0; i < nr_frags; i++) {
+		skb_frag_t *frag = shinfo->frags + i;
+		struct xen_netif_tx_request *txp;
+		unsigned long pending_idx;
+
+		pending_idx = (unsigned long)frag->page;
+
+		txp = &netbk->pending_tx_info[pending_idx].req;
+		frag->page = virt_to_page(idx_to_kaddr(netbk, pending_idx));
+		frag->size = txp->size;
+		frag->page_offset = txp->offset;
+
+		skb->len += txp->size;
+		skb->data_len += txp->size;
+		skb->truesize += txp->size;
+
+		/* Take an extra reference to offset xen_netbk_idx_release */
+		get_page(netbk->mmap_pages[pending_idx]);
+		xen_netbk_idx_release(netbk, pending_idx);
+	}
+}
+
+static int xen_netbk_get_extras(struct xenvif *vif,
+				struct xen_netif_extra_info *extras,
+				int work_to_do)
+{
+	struct xen_netif_extra_info extra;
+	RING_IDX cons = vif->tx.req_cons;
+
+	do {
+		if (unlikely(work_to_do-- <= 0)) {
+			netdev_dbg(vif->dev, "Missing extra info\n");
+			return -EBADR;
+		}
+
+		memcpy(&extra, RING_GET_REQUEST(&vif->tx, cons),
+		       sizeof(extra));
+		if (unlikely(!extra.type ||
+			     extra.type >= XEN_NETIF_EXTRA_TYPE_MAX)) {
+			vif->tx.req_cons = ++cons;
+			netdev_dbg(vif->dev,
+				   "Invalid extra type: %d\n", extra.type);
+			return -EINVAL;
+		}
+
+		memcpy(&extras[extra.type - 1], &extra, sizeof(extra));
+		vif->tx.req_cons = ++cons;
+	} while (extra.flags & XEN_NETIF_EXTRA_FLAG_MORE);
+
+	return work_to_do;
+}
+
+static int netbk_set_skb_gso(struct xenvif *vif,
+			     struct sk_buff *skb,
+			     struct xen_netif_extra_info *gso)
+{
+	if (!gso->u.gso.size) {
+		netdev_dbg(vif->dev, "GSO size must not be zero.\n");
+		return -EINVAL;
+	}
+
+	/* Currently only TCPv4 S.O. is supported. */
+	if (gso->u.gso.type != XEN_NETIF_GSO_TYPE_TCPV4) {
+		netdev_dbg(vif->dev, "Bad GSO type %d.\n", gso->u.gso.type);
+		return -EINVAL;
+	}
+
+	skb_shinfo(skb)->gso_size = gso->u.gso.size;
+	skb_shinfo(skb)->gso_type = SKB_GSO_TCPV4;
+
+	/* Header must be checked, and gso_segs computed. */
+	skb_shinfo(skb)->gso_type |= SKB_GSO_DODGY;
+	skb_shinfo(skb)->gso_segs = 0;
+
+	return 0;
+}
+
+static int checksum_setup(struct xenvif *vif, struct sk_buff *skb)
+{
+	struct iphdr *iph;
+	unsigned char *th;
+	int err = -EPROTO;
+	int recalculate_partial_csum = 0;
+
+	/*
+	 * 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)) {
+		vif->rx_gso_checksum_fixup++;
+		skb->ip_summed = CHECKSUM_PARTIAL;
+		recalculate_partial_csum = 1;
+	}
+
+	/* A non-CHECKSUM_PARTIAL SKB does not require setup. */
+	if (skb->ip_summed != CHECKSUM_PARTIAL)
+		return 0;
+
+	if (skb->protocol != htons(ETH_P_IP))
+		goto out;
+
+	iph = (void *)skb->data;
+	th = skb->data + 4 * iph->ihl;
+	if (th >= skb_tail_pointer(skb))
+		goto out;
+
+	skb->csum_start = th - skb->head;
+	switch (iph->protocol) {
+	case IPPROTO_TCP:
+		skb->csum_offset = offsetof(struct tcphdr, check);
+
+		if (recalculate_partial_csum) {
+			struct tcphdr *tcph = (struct tcphdr *)th;
+			tcph->check = ~csum_tcpudp_magic(iph->saddr, iph->daddr,
+							 skb->len - iph->ihl*4,
+							 IPPROTO_TCP, 0);
+		}
+		break;
+	case IPPROTO_UDP:
+		skb->csum_offset = offsetof(struct udphdr, check);
+
+		if (recalculate_partial_csum) {
+			struct udphdr *udph = (struct udphdr *)th;
+			udph->check = ~csum_tcpudp_magic(iph->saddr, iph->daddr,
+							 skb->len - iph->ihl*4,
+							 IPPROTO_UDP, 0);
+		}
+		break;
+	default:
+		if (net_ratelimit())
+			netdev_err(vif->dev,
+				   "Attempting to checksum a non-TCP/UDP packet, dropping a protocol %d packet\n",
+				   iph->protocol);
+		goto out;
+	}
+
+	if ((th + skb->csum_offset + 2) > skb_tail_pointer(skb))
+		goto out;
+
+	err = 0;
+
+out:
+	return err;
+}
+
+static bool tx_credit_exceeded(struct xenvif *vif, unsigned size)
+{
+	unsigned long now = jiffies;
+	unsigned long next_credit =
+		vif->credit_timeout.expires +
+		msecs_to_jiffies(vif->credit_usec / 1000);
+
+	/* Timer could already be pending in rare cases. */
+	if (timer_pending(&vif->credit_timeout))
+		return true;
+
+	/* Passed the point where we can replenish credit? */
+	if (time_after_eq(now, next_credit)) {
+		vif->credit_timeout.expires = now;
+		tx_add_credit(vif);
+	}
+
+	/* Still too big to send right now? Set a callback. */
+	if (size > vif->remaining_credit) {
+		vif->credit_timeout.data     =
+			(unsigned long)vif;
+		vif->credit_timeout.function =
+			tx_credit_callback;
+		mod_timer(&vif->credit_timeout,
+			  next_credit);
+
+		return true;
+	}
+
+	return false;
+}
+
+static unsigned xen_netbk_tx_build_gops(struct xen_netbk *netbk)
+{
+	struct gnttab_copy *gop = netbk->tx_copy_ops, *request_gop;
+	struct sk_buff *skb;
+	int ret;
+
+	while (((nr_pending_reqs(netbk) + MAX_SKB_FRAGS) < MAX_PENDING_REQS) &&
+		!list_empty(&netbk->net_schedule_list)) {
+		struct xenvif *vif;
+		struct xen_netif_tx_request txreq;
+		struct xen_netif_tx_request txfrags[MAX_SKB_FRAGS];
+		struct page *page;
+		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;
+
+		/* Get a netif from the list with work to do. */
+		vif = poll_net_schedule_list(netbk);
+		if (!vif)
+			continue;
+
+		RING_FINAL_CHECK_FOR_REQUESTS(&vif->tx, work_to_do);
+		if (!work_to_do) {
+			xenvif_put(vif);
+			continue;
+		}
+
+		idx = vif->tx.req_cons;
+		rmb(); /* Ensure that we see the request before we copy it. */
+		memcpy(&txreq, RING_GET_REQUEST(&vif->tx, idx), sizeof(txreq));
+
+		/* Credit-based scheduling. */
+		if (txreq.size > vif->remaining_credit &&
+		    tx_credit_exceeded(vif, txreq.size)) {
+			xenvif_put(vif);
+			continue;
+		}
+
+		vif->remaining_credit -= txreq.size;
+
+		work_to_do--;
+		vif->tx.req_cons = ++idx;
+
+		memset(extras, 0, sizeof(extras));
+		if (txreq.flags & XEN_NETTXF_extra_info) {
+			work_to_do = xen_netbk_get_extras(vif, extras,
+							  work_to_do);
+			idx = vif->tx.req_cons;
+			if (unlikely(work_to_do < 0)) {
+				netbk_tx_err(vif, &txreq, idx);
+				continue;
+			}
+		}
+
+		ret = netbk_count_requests(vif, &txreq, txfrags, work_to_do);
+		if (unlikely(ret < 0)) {
+			netbk_tx_err(vif, &txreq, idx - ret);
+			continue;
+		}
+		idx += ret;
+
+		if (unlikely(txreq.size < ETH_HLEN)) {
+			netdev_dbg(vif->dev,
+				   "Bad packet size: %d\n", txreq.size);
+			netbk_tx_err(vif, &txreq, idx);
+			continue;
+		}
+
+		/* No crossing a page as the payload mustn't fragment. */
+		if (unlikely((txreq.offset + txreq.size) > PAGE_SIZE)) {
+			netdev_dbg(vif->dev,
+				   "txreq.offset: %x, size: %u, end: %lu\n",
+				   txreq.offset, txreq.size,
+				   (txreq.offset&~PAGE_MASK) + txreq.size);
+			netbk_tx_err(vif, &txreq, idx);
+			continue;
+		}
+
+		index = pending_index(netbk->pending_cons);
+		pending_idx = netbk->pending_ring[index];
+
+		data_len = (txreq.size > PKT_PROT_LEN &&
+			    ret < MAX_SKB_FRAGS) ?
+			PKT_PROT_LEN : txreq.size;
+
+		skb = alloc_skb(data_len + NET_SKB_PAD + NET_IP_ALIGN,
+				GFP_ATOMIC | __GFP_NOWARN);
+		if (unlikely(skb == NULL)) {
+			netdev_dbg(vif->dev,
+				   "Can't allocate a skb in start_xmit.\n");
+			netbk_tx_err(vif, &txreq, idx);
+			break;
+		}
+
+		/* Packets passed to netif_rx() must have some headroom. */
+		skb_reserve(skb, NET_SKB_PAD + NET_IP_ALIGN);
+
+		if (extras[XEN_NETIF_EXTRA_TYPE_GSO - 1].type) {
+			struct xen_netif_extra_info *gso;
+			gso = &extras[XEN_NETIF_EXTRA_TYPE_GSO - 1];
+
+			if (netbk_set_skb_gso(vif, skb, gso)) {
+				kfree_skb(skb);
+				netbk_tx_err(vif, &txreq, idx);
+				continue;
+			}
+		}
+
+		/* XXX could copy straight to head */
+		page = xen_netbk_alloc_page(netbk, skb, pending_idx);
+		if (!page) {
+			kfree_skb(skb);
+			netbk_tx_err(vif, &txreq, idx);
+			continue;
+		}
+
+		netbk->mmap_pages[pending_idx] = page;
+
+		gop->source.u.ref = txreq.gref;
+		gop->source.domid = vif->domid;
+		gop->source.offset = txreq.offset;
+
+		gop->dest.u.gmfn = virt_to_mfn(page_address(page));
+		gop->dest.domid = DOMID_SELF;
+		gop->dest.offset = txreq.offset;
+
+		gop->len = txreq.size;
+		gop->flags = GNTCOPY_source_gref;
+
+		gop++;
+
+		memcpy(&netbk->pending_tx_info[pending_idx].req,
+		       &txreq, sizeof(txreq));
+		netbk->pending_tx_info[pending_idx].vif = vif;
+		*((u16 *)skb->data) = pending_idx;
+
+		__skb_put(skb, data_len);
+
+		skb_shinfo(skb)->nr_frags = ret;
+		if (data_len < txreq.size) {
+			skb_shinfo(skb)->nr_frags++;
+			skb_shinfo(skb)->frags[0].page =
+				(void *)(unsigned long)pending_idx;
+		} else {
+			/* Discriminate from any valid pending_idx value. */
+			skb_shinfo(skb)->frags[0].page = (void *)~0UL;
+		}
+
+		__skb_queue_tail(&netbk->tx_queue, skb);
+
+		netbk->pending_cons++;
+
+		request_gop = xen_netbk_get_requests(netbk, vif,
+						     skb, txfrags, gop);
+		if (request_gop == NULL) {
+			kfree_skb(skb);
+			netbk_tx_err(vif, &txreq, idx);
+			continue;
+		}
+		gop = request_gop;
+
+		vif->tx.req_cons = idx;
+		xen_netbk_check_rx_xenvif(vif);
+
+		if ((gop-netbk->tx_copy_ops) >= ARRAY_SIZE(netbk->tx_copy_ops))
+			break;
+	}
+
+	return gop - netbk->tx_copy_ops;
+}
+
+static void xen_netbk_tx_submit(struct xen_netbk *netbk)
+{
+	struct gnttab_copy *gop = netbk->tx_copy_ops;
+	struct sk_buff *skb;
+
+	while ((skb = __skb_dequeue(&netbk->tx_queue)) != NULL) {
+		struct xen_netif_tx_request *txp;
+		struct xenvif *vif;
+		u16 pending_idx;
+		unsigned data_len;
+
+		pending_idx = *((u16 *)skb->data);
+		vif = netbk->pending_tx_info[pending_idx].vif;
+		txp = &netbk->pending_tx_info[pending_idx].req;
+
+		/* Check the remap error code. */
+		if (unlikely(xen_netbk_tx_check_gop(netbk, skb, &gop))) {
+			netdev_dbg(vif->dev, "netback grant failed.\n");
+			skb_shinfo(skb)->nr_frags = 0;
+			kfree_skb(skb);
+			continue;
+		}
+
+		data_len = skb->len;
+		memcpy(skb->data,
+		       (void *)(idx_to_kaddr(netbk, pending_idx)|txp->offset),
+		       data_len);
+		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. */
+			xen_netbk_idx_release(netbk, pending_idx);
+		}
+
+		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;
+
+		xen_netbk_fill_frags(netbk, skb);
+
+		/*
+		 * If the initial fragment was < PKT_PROT_LEN then
+		 * pull through some bytes from the other fragments to
+		 * increase the linear region to PKT_PROT_LEN bytes.
+		 */
+		if (skb_headlen(skb) < PKT_PROT_LEN && skb_is_nonlinear(skb)) {
+			int target = min_t(int, skb->len, PKT_PROT_LEN);
+			__pskb_pull_tail(skb, target - skb_headlen(skb));
+		}
+
+		skb->dev      = vif->dev;
+		skb->protocol = eth_type_trans(skb, skb->dev);
+
+		if (checksum_setup(vif, skb)) {
+			netdev_dbg(vif->dev,
+				   "Can't setup checksum in net_tx_action\n");
+			kfree_skb(skb);
+			continue;
+		}
+
+		vif->dev->stats.rx_bytes += skb->len;
+		vif->dev->stats.rx_packets++;
+
+		xenvif_receive_skb(vif, skb);
+	}
+}
+
+/* Called after netfront has transmitted */
+static void xen_netbk_tx_action(struct xen_netbk *netbk)
+{
+	unsigned nr_gops;
+	int ret;
+
+	nr_gops = xen_netbk_tx_build_gops(netbk);
+
+	if (nr_gops == 0)
+		return;
+	ret = HYPERVISOR_grant_table_op(GNTTABOP_copy,
+					netbk->tx_copy_ops, nr_gops);
+	BUG_ON(ret);
+
+	xen_netbk_tx_submit(netbk);
+
+}
+
+static void xen_netbk_idx_release(struct xen_netbk *netbk, u16 pending_idx)
+{
+	struct xenvif *vif;
+	struct pending_tx_info *pending_tx_info;
+	pending_ring_idx_t index;
+
+	/* Already complete? */
+	if (netbk->mmap_pages[pending_idx] == NULL)
+		return;
+
+	pending_tx_info = &netbk->pending_tx_info[pending_idx];
+
+	vif = pending_tx_info->vif;
+
+	make_tx_response(vif, &pending_tx_info->req, XEN_NETIF_RSP_OKAY);
+
+	index = pending_index(netbk->pending_prod++);
+	netbk->pending_ring[index] = pending_idx;
+
+	xenvif_put(vif);
+
+	netbk->mmap_pages[pending_idx]->mapping = 0;
+	put_page(netbk->mmap_pages[pending_idx]);
+	netbk->mmap_pages[pending_idx] = NULL;
+}
+
+static void make_tx_response(struct xenvif *vif,
+			     struct xen_netif_tx_request *txp,
+			     s8       st)
+{
+	RING_IDX i = vif->tx.rsp_prod_pvt;
+	struct xen_netif_tx_response *resp;
+	int notify;
+
+	resp = RING_GET_RESPONSE(&vif->tx, i);
+	resp->id     = txp->id;
+	resp->status = st;
+
+	if (txp->flags & XEN_NETTXF_extra_info)
+		RING_GET_RESPONSE(&vif->tx, ++i)->status = XEN_NETIF_RSP_NULL;
+
+	vif->tx.rsp_prod_pvt = ++i;
+	RING_PUSH_RESPONSES_AND_CHECK_NOTIFY(&vif->tx, notify);
+	if (notify)
+		notify_remote_via_irq(vif->irq);
+}
+
+static struct xen_netif_rx_response *make_rx_response(struct xenvif *vif,
+					     u16      id,
+					     s8       st,
+					     u16      offset,
+					     u16      size,
+					     u16      flags)
+{
+	RING_IDX i = vif->rx.rsp_prod_pvt;
+	struct xen_netif_rx_response *resp;
+
+	resp = RING_GET_RESPONSE(&vif->rx, i);
+	resp->offset     = offset;
+	resp->flags      = flags;
+	resp->id         = id;
+	resp->status     = (s16)size;
+	if (st < 0)
+		resp->status = (s16)st;
+
+	vif->rx.rsp_prod_pvt = ++i;
+
+	return resp;
+}
+
+static inline int rx_work_todo(struct xen_netbk *netbk)
+{
+	return !skb_queue_empty(&netbk->rx_queue);
+}
+
+static inline int tx_work_todo(struct xen_netbk *netbk)
+{
+
+	if (((nr_pending_reqs(netbk) + MAX_SKB_FRAGS) < MAX_PENDING_REQS) &&
+			!list_empty(&netbk->net_schedule_list))
+		return 1;
+
+	return 0;
+}
+
+static int xen_netbk_kthread(void *data)
+{
+	struct xen_netbk *netbk = data;
+	while (!kthread_should_stop()) {
+		wait_event_interruptible(netbk->wq,
+				rx_work_todo(netbk) ||
+				tx_work_todo(netbk) ||
+				kthread_should_stop());
+		cond_resched();
+
+		if (kthread_should_stop())
+			break;
+
+		if (rx_work_todo(netbk))
+			xen_netbk_rx_action(netbk);
+
+		if (tx_work_todo(netbk))
+			xen_netbk_tx_action(netbk);
+	}
+
+	return 0;
+}
+
+void xen_netbk_unmap_frontend_rings(struct xenvif *vif)
+{
+	struct gnttab_unmap_grant_ref op;
+
+	if (vif->tx.sring) {
+		gnttab_set_unmap_op(&op, (unsigned long)vif->tx_comms_area->addr,
+				    GNTMAP_host_map, vif->tx_shmem_handle);
+
+		if (HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref, &op, 1))
+			BUG();
+	}
+
+	if (vif->rx.sring) {
+		gnttab_set_unmap_op(&op, (unsigned long)vif->rx_comms_area->addr,
+				    GNTMAP_host_map, vif->rx_shmem_handle);
+
+		if (HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref, &op, 1))
+			BUG();
+	}
+	if (vif->rx_comms_area)
+		free_vm_area(vif->rx_comms_area);
+	if (vif->tx_comms_area)
+		free_vm_area(vif->tx_comms_area);
+}
+
+int xen_netbk_map_frontend_rings(struct xenvif *vif,
+				 grant_ref_t tx_ring_ref,
+				 grant_ref_t rx_ring_ref)
+{
+	struct gnttab_map_grant_ref op;
+	struct xen_netif_tx_sring *txs;
+	struct xen_netif_rx_sring *rxs;
+
+	int err = -ENOMEM;
+
+	vif->tx_comms_area = alloc_vm_area(PAGE_SIZE);
+	if (vif->tx_comms_area == NULL)
+		goto err;
+
+	vif->rx_comms_area = alloc_vm_area(PAGE_SIZE);
+	if (vif->rx_comms_area == NULL)
+		goto err;
+
+	gnttab_set_map_op(&op, (unsigned long)vif->tx_comms_area->addr,
+			  GNTMAP_host_map, tx_ring_ref, vif->domid);
+
+	if (HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref, &op, 1))
+		BUG();
+
+	if (op.status) {
+		netdev_warn(vif->dev,
+			    "failed to map tx ring. err=%d status=%d\n",
+			    err, op.status);
+		err = op.status;
+		goto err;
+	}
+
+	vif->tx_shmem_ref    = tx_ring_ref;
+	vif->tx_shmem_handle = op.handle;
+
+	txs = (struct xen_netif_tx_sring *)vif->tx_comms_area->addr;
+	BACK_RING_INIT(&vif->tx, txs, PAGE_SIZE);
+
+	gnttab_set_map_op(&op, (unsigned long)vif->rx_comms_area->addr,
+			  GNTMAP_host_map, rx_ring_ref, vif->domid);
+
+	if (HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref, &op, 1))
+		BUG();
+
+	if (op.status) {
+		netdev_warn(vif->dev,
+			    "failed to map rx ring. err=%d status=%d\n",
+			    err, op.status);
+		err = op.status;
+		goto err;
+	}
+
+	vif->rx_shmem_ref     = rx_ring_ref;
+	vif->rx_shmem_handle  = op.handle;
+	vif->rx_req_cons_peek = 0;
+
+	rxs = (struct xen_netif_rx_sring *)vif->rx_comms_area->addr;
+	BACK_RING_INIT(&vif->rx, rxs, PAGE_SIZE);
+
+	return 0;
+
+err:
+	xen_netbk_unmap_frontend_rings(vif);
+	return err;
+}
+
+static int __init netback_init(void)
+{
+	int i;
+	int rc = 0;
+	int group;
+
+	if (!xen_pv_domain())
+		return -ENODEV;
+
+	xen_netbk_group_nr = num_online_cpus();
+	xen_netbk = vzalloc(sizeof(struct xen_netbk) * xen_netbk_group_nr);
+	if (!xen_netbk) {
+		printk(KERN_ALERT "%s: out of memory\n", __func__);
+		return -ENOMEM;
+	}
+
+	for (group = 0; group < xen_netbk_group_nr; group++) {
+		struct xen_netbk *netbk = &xen_netbk[group];
+		skb_queue_head_init(&netbk->rx_queue);
+		skb_queue_head_init(&netbk->tx_queue);
+
+		init_timer(&netbk->net_timer);
+		netbk->net_timer.data = (unsigned long)netbk;
+		netbk->net_timer.function = xen_netbk_alarm;
+
+		netbk->pending_cons = 0;
+		netbk->pending_prod = MAX_PENDING_REQS;
+		for (i = 0; i < MAX_PENDING_REQS; i++)
+			netbk->pending_ring[i] = i;
+
+		init_waitqueue_head(&netbk->wq);
+		netbk->task = kthread_create(xen_netbk_kthread,
+					     (void *)netbk,
+					     "netback/%u", group);
+
+		if (IS_ERR(netbk->task)) {
+			printk(KERN_ALERT "kthread_run() fails at netback\n");
+			del_timer(&netbk->net_timer);
+			rc = PTR_ERR(netbk->task);
+			goto failed_init;
+		}
+
+		kthread_bind(netbk->task, group);
+
+		INIT_LIST_HEAD(&netbk->net_schedule_list);
+
+		spin_lock_init(&netbk->net_schedule_list_lock);
+
+		atomic_set(&netbk->netfront_count, 0);
+
+		wake_up_process(netbk->task);
+	}
+
+	rc = xenvif_xenbus_init();
+	if (rc)
+		goto failed_init;
+
+	return 0;
+
+failed_init:
+	while (--group >= 0) {
+		struct xen_netbk *netbk = &xen_netbk[group];
+		for (i = 0; i < MAX_PENDING_REQS; i++) {
+			if (netbk->mmap_pages[i])
+				__free_page(netbk->mmap_pages[i]);
+		}
+		del_timer(&netbk->net_timer);
+		kthread_stop(netbk->task);
+	}
+	vfree(xen_netbk);
+	return rc;
+
+}
+
+module_init(netback_init);
+
+MODULE_LICENSE("Dual BSD/GPL");