drivers/net/xen-netback/interface.c - arm/linux-arm64-legacy - Git at Google

 /*
  * Network-device interface management.
  *
  * Copyright (c) 2004-2005, Keir 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/ethtool.h>
 #include <linux/rtnetlink.h>
 #include <linux/if_vlan.h>
 #include <linux/vmalloc.h>

 #include <xen/events.h>
 #include <asm/xen/hypercall.h>

 #define XENVIF_QUEUE_LENGTH 32
 #define XENVIF_NAPI_WEIGHT  64

 int xenvif_schedulable(struct xenvif *vif)
 {
 	return netif_running(vif->dev) && netif_carrier_ok(vif->dev);
 }

 static irqreturn_t xenvif_tx_interrupt(int irq, void *dev_id)
 {
 	struct xenvif *vif = dev_id;

 	if (RING_HAS_UNCONSUMED_REQUESTS(&vif->tx))
 		napi_schedule(&vif->napi);

 	return IRQ_HANDLED;
 }

 static int xenvif_poll(struct napi_struct *napi, int budget)
 {
 	struct xenvif *vif = container_of(napi, struct xenvif, napi);
 	int work_done;

 	work_done = xenvif_tx_action(vif, budget);

 	if (work_done < budget) {
 		int more_to_do = 0;
 		unsigned long flags;

 		/* It is necessary to disable IRQ before calling
 		 * RING_HAS_UNCONSUMED_REQUESTS. Otherwise we might
 		 * lose event from the frontend.
 		 *
 		 * Consider:
 		 *   RING_HAS_UNCONSUMED_REQUESTS
 		 *   <frontend generates event to trigger napi_schedule>
 		 *   __napi_complete
 		 *
 		 * This handler is still in scheduled state so the
 		 * event has no effect at all. After __napi_complete
 		 * this handler is descheduled and cannot get
 		 * scheduled again. We lose event in this case and the ring
 		 * will be completely stalled.
 		 */

 		local_irq_save(flags);

 		RING_FINAL_CHECK_FOR_REQUESTS(&vif->tx, more_to_do);
 		if (!more_to_do)
 			__napi_complete(napi);

 		local_irq_restore(flags);
 	}

 	return work_done;
 }

 static irqreturn_t xenvif_rx_interrupt(int irq, void *dev_id)
 {
 	struct xenvif *vif = dev_id;

 	xenvif_kick_thread(vif);

 	return IRQ_HANDLED;
 }

 static irqreturn_t xenvif_interrupt(int irq, void *dev_id)
 {
 	xenvif_tx_interrupt(irq, dev_id);
 	xenvif_rx_interrupt(irq, dev_id);

 	return IRQ_HANDLED;
 }

 static int xenvif_start_xmit(struct sk_buff *skb, struct net_device *dev)
 {
 	struct xenvif *vif = netdev_priv(dev);
 	int min_slots_needed;

 	BUG_ON(skb->dev != dev);

 	/* Drop the packet if vif is not ready */
 	if (vif->task == NULL || !xenvif_schedulable(vif))
 		goto drop;

 	/* At best we'll need one slot for the header and one for each
 	 * frag.
 	 */
 	min_slots_needed = 1 + skb_shinfo(skb)->nr_frags;

 	/* If the skb is GSO then we'll also need an extra slot for the
 	 * metadata.
 	 */
 	if (skb_is_gso(skb))
 		min_slots_needed++;

 	/* If the skb can't possibly fit in the remaining slots
 	 * then turn off the queue to give the ring a chance to
 	 * drain.
 	 */
 	if (!xenvif_rx_ring_slots_available(vif, min_slots_needed))
 		xenvif_stop_queue(vif);

 	skb_queue_tail(&vif->rx_queue, skb);
 	xenvif_kick_thread(vif);

 	return NETDEV_TX_OK;

  drop:
 	vif->dev->stats.tx_dropped++;
 	dev_kfree_skb(skb);
 	return NETDEV_TX_OK;
 }

 static struct net_device_stats *xenvif_get_stats(struct net_device *dev)
 {
 	struct xenvif *vif = netdev_priv(dev);
 	return &vif->dev->stats;
 }

 static void xenvif_up(struct xenvif *vif)
 {
 	napi_enable(&vif->napi);
 	enable_irq(vif->tx_irq);
 	if (vif->tx_irq != vif->rx_irq)
 		enable_irq(vif->rx_irq);
 	xenvif_check_rx_xenvif(vif);
 }

 static void xenvif_down(struct xenvif *vif)
 {
 	napi_disable(&vif->napi);
 	disable_irq(vif->tx_irq);
 	if (vif->tx_irq != vif->rx_irq)
 		disable_irq(vif->rx_irq);
 	del_timer_sync(&vif->credit_timeout);
 }

 static int xenvif_open(struct net_device *dev)
 {
 	struct xenvif *vif = netdev_priv(dev);
 	if (netif_carrier_ok(dev))
 		xenvif_up(vif);
 	netif_start_queue(dev);
 	return 0;
 }

 static int xenvif_close(struct net_device *dev)
 {
 	struct xenvif *vif = netdev_priv(dev);
 	if (netif_carrier_ok(dev))
 		xenvif_down(vif);
 	netif_stop_queue(dev);
 	return 0;
 }

 static int xenvif_change_mtu(struct net_device *dev, int mtu)
 {
 	struct xenvif *vif = netdev_priv(dev);
 	int max = vif->can_sg ? 65535 - VLAN_ETH_HLEN : ETH_DATA_LEN;

 	if (mtu > max)
 		return -EINVAL;
 	dev->mtu = mtu;
 	return 0;
 }

 static netdev_features_t xenvif_fix_features(struct net_device *dev,
 	netdev_features_t features)
 {
 	struct xenvif *vif = netdev_priv(dev);

 	if (!vif->can_sg)
 		features &= ~NETIF_F_SG;
 	if (~(vif->gso_mask | vif->gso_prefix_mask) & GSO_BIT(TCPV4))
 		features &= ~NETIF_F_TSO;
 	if (~(vif->gso_mask | vif->gso_prefix_mask) & GSO_BIT(TCPV6))
 		features &= ~NETIF_F_TSO6;
 	if (!vif->ip_csum)
 		features &= ~NETIF_F_IP_CSUM;
 	if (!vif->ipv6_csum)
 		features &= ~NETIF_F_IPV6_CSUM;

 	return features;
 }

 static const struct xenvif_stat {
 	char name[ETH_GSTRING_LEN];
 	u16 offset;
 } xenvif_stats[] = {
 	{
 		"rx_gso_checksum_fixup",
 		offsetof(struct xenvif, rx_gso_checksum_fixup)
 	},
 };

 static int xenvif_get_sset_count(struct net_device *dev, int string_set)
 {
 	switch (string_set) {
 	case ETH_SS_STATS:
 		return ARRAY_SIZE(xenvif_stats);
 	default:
 		return -EINVAL;
 	}
 }

 static void xenvif_get_ethtool_stats(struct net_device *dev,
 				     struct ethtool_stats *stats, u64 * data)
 {
 	void *vif = netdev_priv(dev);
 	int i;

 	for (i = 0; i < ARRAY_SIZE(xenvif_stats); i++)
 		data[i] = *(unsigned long *)(vif + xenvif_stats[i].offset);
 }

 static void xenvif_get_strings(struct net_device *dev, u32 stringset, u8 * data)
 {
 	int i;

 	switch (stringset) {
 	case ETH_SS_STATS:
 		for (i = 0; i < ARRAY_SIZE(xenvif_stats); i++)
 			memcpy(data + i * ETH_GSTRING_LEN,
 			       xenvif_stats[i].name, ETH_GSTRING_LEN);
 		break;
 	}
 }

 static const struct ethtool_ops xenvif_ethtool_ops = {
 	.get_link	= ethtool_op_get_link,

 	.get_sset_count = xenvif_get_sset_count,
 	.get_ethtool_stats = xenvif_get_ethtool_stats,
 	.get_strings = xenvif_get_strings,
 };

 static const struct net_device_ops xenvif_netdev_ops = {
 	.ndo_start_xmit	= xenvif_start_xmit,
 	.ndo_get_stats	= xenvif_get_stats,
 	.ndo_open	= xenvif_open,
 	.ndo_stop	= xenvif_close,
 	.ndo_change_mtu	= xenvif_change_mtu,
 	.ndo_fix_features = xenvif_fix_features,
 	.ndo_set_mac_address = eth_mac_addr,
 	.ndo_validate_addr   = eth_validate_addr,
 };

 struct xenvif *xenvif_alloc(struct device *parent, domid_t domid,
 			    unsigned int handle)
 {
 	int err;
 	struct net_device *dev;
 	struct xenvif *vif;
 	char name[IFNAMSIZ] = {};
 	int i;

 	snprintf(name, IFNAMSIZ - 1, "vif%u.%u", domid, handle);
 	dev = alloc_netdev(sizeof(struct xenvif), name, ether_setup);
 	if (dev == NULL) {
 		pr_warn("Could not allocate netdev for %s\n", name);
 		return ERR_PTR(-ENOMEM);
 	}

 	SET_NETDEV_DEV(dev, parent);

 	vif = netdev_priv(dev);

 	vif->grant_copy_op = vmalloc(sizeof(struct gnttab_copy) *
 				     MAX_GRANT_COPY_OPS);
 	if (vif->grant_copy_op == NULL) {
 		pr_warn("Could not allocate grant copy space for %s\n", name);
 		free_netdev(dev);
 		return ERR_PTR(-ENOMEM);
 	}

 	vif->domid  = domid;
 	vif->handle = handle;
 	vif->can_sg = 1;
 	vif->ip_csum = 1;
 	vif->dev = dev;

 	vif->credit_bytes = vif->remaining_credit = ~0UL;
 	vif->credit_usec  = 0UL;
 	init_timer(&vif->credit_timeout);
 	vif->credit_window_start = get_jiffies_64();

 	dev->netdev_ops	= &xenvif_netdev_ops;
 	dev->hw_features = NETIF_F_SG |
 		NETIF_F_IP_CSUM | NETIF_F_IPV6_CSUM |
 		NETIF_F_TSO | NETIF_F_TSO6;
 	dev->features = dev->hw_features | NETIF_F_RXCSUM;
 	SET_ETHTOOL_OPS(dev, &xenvif_ethtool_ops);

 	dev->tx_queue_len = XENVIF_QUEUE_LENGTH;

 	skb_queue_head_init(&vif->rx_queue);
 	skb_queue_head_init(&vif->tx_queue);

 	vif->pending_cons = 0;
 	vif->pending_prod = MAX_PENDING_REQS;
 	for (i = 0; i < MAX_PENDING_REQS; i++)
 		vif->pending_ring[i] = i;
 	for (i = 0; i < MAX_PENDING_REQS; i++)
 		vif->mmap_pages[i] = NULL;

 	/*
 	 * Initialise a dummy MAC address. We choose the numerically
 	 * largest non-broadcast address to prevent the address getting
 	 * stolen by an Ethernet bridge for STP purposes.
 	 * (FE:FF:FF:FF:FF:FF)
 	 */
 	memset(dev->dev_addr, 0xFF, ETH_ALEN);
 	dev->dev_addr[0] &= ~0x01;

 	netif_napi_add(dev, &vif->napi, xenvif_poll, XENVIF_NAPI_WEIGHT);

 	netif_carrier_off(dev);

 	err = register_netdev(dev);
 	if (err) {
 		netdev_warn(dev, "Could not register device: err=%d\n", err);
 		free_netdev(dev);
 		return ERR_PTR(err);
 	}

 	netdev_dbg(dev, "Successfully created xenvif\n");

 	__module_get(THIS_MODULE);

 	return vif;
 }

 int xenvif_connect(struct xenvif *vif, unsigned long tx_ring_ref,
 		   unsigned long rx_ring_ref, unsigned int tx_evtchn,
 		   unsigned int rx_evtchn)
 {
 	struct task_struct *task;
 	int err = -ENOMEM;

 	BUG_ON(vif->tx_irq);
 	BUG_ON(vif->task);

 	err = xenvif_map_frontend_rings(vif, tx_ring_ref, rx_ring_ref);
 	if (err < 0)
 		goto err;

 	init_waitqueue_head(&vif->wq);

 	if (tx_evtchn == rx_evtchn) {
 		/* feature-split-event-channels == 0 */
 		err = bind_interdomain_evtchn_to_irqhandler(
 			vif->domid, tx_evtchn, xenvif_interrupt, 0,
 			vif->dev->name, vif);
 		if (err < 0)
 			goto err_unmap;
 		vif->tx_irq = vif->rx_irq = err;
 		disable_irq(vif->tx_irq);
 	} else {
 		/* feature-split-event-channels == 1 */
 		snprintf(vif->tx_irq_name, sizeof(vif->tx_irq_name),
 			 "%s-tx", vif->dev->name);
 		err = bind_interdomain_evtchn_to_irqhandler(
 			vif->domid, tx_evtchn, xenvif_tx_interrupt, 0,
 			vif->tx_irq_name, vif);
 		if (err < 0)
 			goto err_unmap;
 		vif->tx_irq = err;
 		disable_irq(vif->tx_irq);

 		snprintf(vif->rx_irq_name, sizeof(vif->rx_irq_name),
 			 "%s-rx", vif->dev->name);
 		err = bind_interdomain_evtchn_to_irqhandler(
 			vif->domid, rx_evtchn, xenvif_rx_interrupt, 0,
 			vif->rx_irq_name, vif);
 		if (err < 0)
 			goto err_tx_unbind;
 		vif->rx_irq = err;
 		disable_irq(vif->rx_irq);
 	}

 	task = kthread_create(xenvif_kthread,
 			      (void *)vif, "%s", vif->dev->name);
 	if (IS_ERR(task)) {
 		pr_warn("Could not allocate kthread for %s\n", vif->dev->name);
 		err = PTR_ERR(task);
 		goto err_rx_unbind;
 	}

 	vif->task = task;

 	rtnl_lock();
 	if (!vif->can_sg && vif->dev->mtu > ETH_DATA_LEN)
 		dev_set_mtu(vif->dev, ETH_DATA_LEN);
 	netdev_update_features(vif->dev);
 	netif_carrier_on(vif->dev);
 	if (netif_running(vif->dev))
 		xenvif_up(vif);
 	rtnl_unlock();

 	wake_up_process(vif->task);

 	return 0;

 err_rx_unbind:
 	unbind_from_irqhandler(vif->rx_irq, vif);
 	vif->rx_irq = 0;
 err_tx_unbind:
 	unbind_from_irqhandler(vif->tx_irq, vif);
 	vif->tx_irq = 0;
 err_unmap:
 	xenvif_unmap_frontend_rings(vif);
 err:
 	module_put(THIS_MODULE);
 	return err;
 }

 void xenvif_carrier_off(struct xenvif *vif)
 {
 	struct net_device *dev = vif->dev;

 	rtnl_lock();
 	netif_carrier_off(dev); /* discard queued packets */
 	if (netif_running(dev))
 		xenvif_down(vif);
 	rtnl_unlock();
 }

 void xenvif_disconnect(struct xenvif *vif)
 {
 	if (netif_carrier_ok(vif->dev))
 		xenvif_carrier_off(vif);

 	if (vif->task) {
 		kthread_stop(vif->task);
 		vif->task = NULL;
 	}

 	if (vif->tx_irq) {
 		if (vif->tx_irq == vif->rx_irq)
 			unbind_from_irqhandler(vif->tx_irq, vif);
 		else {
 			unbind_from_irqhandler(vif->tx_irq, vif);
 			unbind_from_irqhandler(vif->rx_irq, vif);
 		}
 		vif->tx_irq = 0;
 	}

 	xenvif_unmap_frontend_rings(vif);
 }

 void xenvif_free(struct xenvif *vif)
 {
 	netif_napi_del(&vif->napi);

 	unregister_netdev(vif->dev);

 	vfree(vif->grant_copy_op);
 	free_netdev(vif->dev);

 	module_put(THIS_MODULE);
 }
	/*
	* Network-device interface management.
	*
	* Copyright (c) 2004-2005, Keir 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/ethtool.h>
	#include <linux/rtnetlink.h>
	#include <linux/if_vlan.h>
	#include <linux/vmalloc.h>

	#include <xen/events.h>
	#include <asm/xen/hypercall.h>

	#define XENVIF_QUEUE_LENGTH 32
	#define XENVIF_NAPI_WEIGHT 64

	int xenvif_schedulable(struct xenvif *vif)
	{
	return netif_running(vif->dev) && netif_carrier_ok(vif->dev);
	}

	static irqreturn_t xenvif_tx_interrupt(int irq, void *dev_id)
	{
	struct xenvif *vif = dev_id;

	if (RING_HAS_UNCONSUMED_REQUESTS(&vif->tx))
	napi_schedule(&vif->napi);

	return IRQ_HANDLED;
	}

	static int xenvif_poll(struct napi_struct *napi, int budget)
	{
	struct xenvif *vif = container_of(napi, struct xenvif, napi);
	int work_done;

	work_done = xenvif_tx_action(vif, budget);

	if (work_done < budget) {
	int more_to_do = 0;
	unsigned long flags;

	/* It is necessary to disable IRQ before calling
	* RING_HAS_UNCONSUMED_REQUESTS. Otherwise we might
	* lose event from the frontend.
	*
	* Consider:
	* RING_HAS_UNCONSUMED_REQUESTS
	* <frontend generates event to trigger napi_schedule>
	* __napi_complete
	*
	* This handler is still in scheduled state so the
	* event has no effect at all. After __napi_complete
	* this handler is descheduled and cannot get
	* scheduled again. We lose event in this case and the ring
	* will be completely stalled.
	*/

	local_irq_save(flags);

	RING_FINAL_CHECK_FOR_REQUESTS(&vif->tx, more_to_do);
	if (!more_to_do)
	__napi_complete(napi);

	local_irq_restore(flags);
	}

	return work_done;
	}

	static irqreturn_t xenvif_rx_interrupt(int irq, void *dev_id)
	{
	struct xenvif *vif = dev_id;

	xenvif_kick_thread(vif);

	return IRQ_HANDLED;
	}

	static irqreturn_t xenvif_interrupt(int irq, void *dev_id)
	{
	xenvif_tx_interrupt(irq, dev_id);
	xenvif_rx_interrupt(irq, dev_id);

	return IRQ_HANDLED;
	}

	static int xenvif_start_xmit(struct sk_buff skb, struct net_device dev)
	{
	struct xenvif *vif = netdev_priv(dev);
	int min_slots_needed;

	BUG_ON(skb->dev != dev);

	/* Drop the packet if vif is not ready */
	if (vif->task == NULL \|\| !xenvif_schedulable(vif))
	goto drop;

	/* At best we'll need one slot for the header and one for each
	* frag.
	*/
	min_slots_needed = 1 + skb_shinfo(skb)->nr_frags;

	/* If the skb is GSO then we'll also need an extra slot for the
	* metadata.
	*/
	if (skb_is_gso(skb))
	min_slots_needed++;

	/* If the skb can't possibly fit in the remaining slots
	* then turn off the queue to give the ring a chance to
	* drain.
	*/
	if (!xenvif_rx_ring_slots_available(vif, min_slots_needed))
	xenvif_stop_queue(vif);

	skb_queue_tail(&vif->rx_queue, skb);
	xenvif_kick_thread(vif);

	return NETDEV_TX_OK;

	drop:
	vif->dev->stats.tx_dropped++;
	dev_kfree_skb(skb);
	return NETDEV_TX_OK;
	}

	static struct net_device_stats xenvif_get_stats(struct net_device dev)
	{
	struct xenvif *vif = netdev_priv(dev);
	return &vif->dev->stats;
	}

	static void xenvif_up(struct xenvif *vif)
	{
	napi_enable(&vif->napi);
	enable_irq(vif->tx_irq);
	if (vif->tx_irq != vif->rx_irq)
	enable_irq(vif->rx_irq);
	xenvif_check_rx_xenvif(vif);
	}

	static void xenvif_down(struct xenvif *vif)
	{
	napi_disable(&vif->napi);
	disable_irq(vif->tx_irq);
	if (vif->tx_irq != vif->rx_irq)
	disable_irq(vif->rx_irq);
	del_timer_sync(&vif->credit_timeout);
	}

	static int xenvif_open(struct net_device *dev)
	{
	struct xenvif *vif = netdev_priv(dev);
	if (netif_carrier_ok(dev))
	xenvif_up(vif);
	netif_start_queue(dev);
	return 0;
	}

	static int xenvif_close(struct net_device *dev)
	{
	struct xenvif *vif = netdev_priv(dev);
	if (netif_carrier_ok(dev))
	xenvif_down(vif);
	netif_stop_queue(dev);
	return 0;
	}

	static int xenvif_change_mtu(struct net_device *dev, int mtu)
	{
	struct xenvif *vif = netdev_priv(dev);
	int max = vif->can_sg ? 65535 - VLAN_ETH_HLEN : ETH_DATA_LEN;

	if (mtu > max)
	return -EINVAL;
	dev->mtu = mtu;
	return 0;
	}

	static netdev_features_t xenvif_fix_features(struct net_device *dev,
	netdev_features_t features)
	{
	struct xenvif *vif = netdev_priv(dev);

	if (!vif->can_sg)
	features &= ~NETIF_F_SG;
	if (~(vif->gso_mask \| vif->gso_prefix_mask) & GSO_BIT(TCPV4))
	features &= ~NETIF_F_TSO;
	if (~(vif->gso_mask \| vif->gso_prefix_mask) & GSO_BIT(TCPV6))
	features &= ~NETIF_F_TSO6;
	if (!vif->ip_csum)
	features &= ~NETIF_F_IP_CSUM;
	if (!vif->ipv6_csum)
	features &= ~NETIF_F_IPV6_CSUM;

	return features;
	}

	static const struct xenvif_stat {
	char name[ETH_GSTRING_LEN];
	u16 offset;
	} xenvif_stats[] = {
	{
	"rx_gso_checksum_fixup",
	offsetof(struct xenvif, rx_gso_checksum_fixup)
	},
	};

	static int xenvif_get_sset_count(struct net_device *dev, int string_set)
	{
	switch (string_set) {
	case ETH_SS_STATS:
	return ARRAY_SIZE(xenvif_stats);
	default:
	return -EINVAL;
	}
	}

	static void xenvif_get_ethtool_stats(struct net_device *dev,
	struct ethtool_stats stats, u64 data)
	{
	void *vif = netdev_priv(dev);
	int i;

	for (i = 0; i < ARRAY_SIZE(xenvif_stats); i++)
	data[i] = (unsigned long )(vif + xenvif_stats[i].offset);
	}

	static void xenvif_get_strings(struct net_device dev, u32 stringset, u8 data)
	{
	int i;

	switch (stringset) {
	case ETH_SS_STATS:
	for (i = 0; i < ARRAY_SIZE(xenvif_stats); i++)
	memcpy(data + i * ETH_GSTRING_LEN,
	xenvif_stats[i].name, ETH_GSTRING_LEN);
	break;
	}
	}

	static const struct ethtool_ops xenvif_ethtool_ops = {
	.get_link = ethtool_op_get_link,

	.get_sset_count = xenvif_get_sset_count,
	.get_ethtool_stats = xenvif_get_ethtool_stats,
	.get_strings = xenvif_get_strings,
	};

	static const struct net_device_ops xenvif_netdev_ops = {
	.ndo_start_xmit = xenvif_start_xmit,
	.ndo_get_stats = xenvif_get_stats,
	.ndo_open = xenvif_open,
	.ndo_stop = xenvif_close,
	.ndo_change_mtu = xenvif_change_mtu,
	.ndo_fix_features = xenvif_fix_features,
	.ndo_set_mac_address = eth_mac_addr,
	.ndo_validate_addr = eth_validate_addr,
	};

	struct xenvif xenvif_alloc(struct device parent, domid_t domid,
	unsigned int handle)
	{
	int err;
	struct net_device *dev;
	struct xenvif *vif;
	char name[IFNAMSIZ] = {};
	int i;

	snprintf(name, IFNAMSIZ - 1, "vif%u.%u", domid, handle);
	dev = alloc_netdev(sizeof(struct xenvif), name, ether_setup);
	if (dev == NULL) {
	pr_warn("Could not allocate netdev for %s\n", name);
	return ERR_PTR(-ENOMEM);
	}

	SET_NETDEV_DEV(dev, parent);

	vif = netdev_priv(dev);

	vif->grant_copy_op = vmalloc(sizeof(struct gnttab_copy) *
	MAX_GRANT_COPY_OPS);
	if (vif->grant_copy_op == NULL) {
	pr_warn("Could not allocate grant copy space for %s\n", name);
	free_netdev(dev);
	return ERR_PTR(-ENOMEM);
	}

	vif->domid = domid;
	vif->handle = handle;
	vif->can_sg = 1;
	vif->ip_csum = 1;
	vif->dev = dev;

	vif->credit_bytes = vif->remaining_credit = ~0UL;
	vif->credit_usec = 0UL;
	init_timer(&vif->credit_timeout);
	vif->credit_window_start = get_jiffies_64();

	dev->netdev_ops = &xenvif_netdev_ops;
	dev->hw_features = NETIF_F_SG \|
	NETIF_F_IP_CSUM \| NETIF_F_IPV6_CSUM \|
	NETIF_F_TSO \| NETIF_F_TSO6;
	dev->features = dev->hw_features \| NETIF_F_RXCSUM;
	SET_ETHTOOL_OPS(dev, &xenvif_ethtool_ops);

	dev->tx_queue_len = XENVIF_QUEUE_LENGTH;

	skb_queue_head_init(&vif->rx_queue);
	skb_queue_head_init(&vif->tx_queue);

	vif->pending_cons = 0;
	vif->pending_prod = MAX_PENDING_REQS;
	for (i = 0; i < MAX_PENDING_REQS; i++)
	vif->pending_ring[i] = i;
	for (i = 0; i < MAX_PENDING_REQS; i++)
	vif->mmap_pages[i] = NULL;

	/*
	* Initialise a dummy MAC address. We choose the numerically
	* largest non-broadcast address to prevent the address getting
	* stolen by an Ethernet bridge for STP purposes.
	* (FE:FF:FF:FF:FF:FF)
	*/
	memset(dev->dev_addr, 0xFF, ETH_ALEN);
	dev->dev_addr[0] &= ~0x01;

	netif_napi_add(dev, &vif->napi, xenvif_poll, XENVIF_NAPI_WEIGHT);

	netif_carrier_off(dev);

	err = register_netdev(dev);
	if (err) {
	netdev_warn(dev, "Could not register device: err=%d\n", err);
	free_netdev(dev);
	return ERR_PTR(err);
	}

	netdev_dbg(dev, "Successfully created xenvif\n");

	__module_get(THIS_MODULE);

	return vif;
	}

	int xenvif_connect(struct xenvif *vif, unsigned long tx_ring_ref,
	unsigned long rx_ring_ref, unsigned int tx_evtchn,
	unsigned int rx_evtchn)
	{
	struct task_struct *task;
	int err = -ENOMEM;

	BUG_ON(vif->tx_irq);
	BUG_ON(vif->task);

	err = xenvif_map_frontend_rings(vif, tx_ring_ref, rx_ring_ref);
	if (err < 0)
	goto err;

	init_waitqueue_head(&vif->wq);

	if (tx_evtchn == rx_evtchn) {
	/* feature-split-event-channels == 0 */
	err = bind_interdomain_evtchn_to_irqhandler(
	vif->domid, tx_evtchn, xenvif_interrupt, 0,
	vif->dev->name, vif);
	if (err < 0)
	goto err_unmap;
	vif->tx_irq = vif->rx_irq = err;
	disable_irq(vif->tx_irq);
	} else {
	/* feature-split-event-channels == 1 */
	snprintf(vif->tx_irq_name, sizeof(vif->tx_irq_name),
	"%s-tx", vif->dev->name);
	err = bind_interdomain_evtchn_to_irqhandler(
	vif->domid, tx_evtchn, xenvif_tx_interrupt, 0,
	vif->tx_irq_name, vif);
	if (err < 0)
	goto err_unmap;
	vif->tx_irq = err;
	disable_irq(vif->tx_irq);

	snprintf(vif->rx_irq_name, sizeof(vif->rx_irq_name),
	"%s-rx", vif->dev->name);
	err = bind_interdomain_evtchn_to_irqhandler(
	vif->domid, rx_evtchn, xenvif_rx_interrupt, 0,
	vif->rx_irq_name, vif);
	if (err < 0)
	goto err_tx_unbind;
	vif->rx_irq = err;
	disable_irq(vif->rx_irq);
	}

	task = kthread_create(xenvif_kthread,
	(void *)vif, "%s", vif->dev->name);
	if (IS_ERR(task)) {
	pr_warn("Could not allocate kthread for %s\n", vif->dev->name);
	err = PTR_ERR(task);
	goto err_rx_unbind;
	}

	vif->task = task;

	rtnl_lock();
	if (!vif->can_sg && vif->dev->mtu > ETH_DATA_LEN)
	dev_set_mtu(vif->dev, ETH_DATA_LEN);
	netdev_update_features(vif->dev);
	netif_carrier_on(vif->dev);
	if (netif_running(vif->dev))
	xenvif_up(vif);
	rtnl_unlock();

	wake_up_process(vif->task);

	return 0;

	err_rx_unbind:
	unbind_from_irqhandler(vif->rx_irq, vif);
	vif->rx_irq = 0;
	err_tx_unbind:
	unbind_from_irqhandler(vif->tx_irq, vif);
	vif->tx_irq = 0;
	err_unmap:
	xenvif_unmap_frontend_rings(vif);
	err:
	module_put(THIS_MODULE);
	return err;
	}

	void xenvif_carrier_off(struct xenvif *vif)
	{
	struct net_device *dev = vif->dev;

	rtnl_lock();
	netif_carrier_off(dev); /* discard queued packets */
	if (netif_running(dev))
	xenvif_down(vif);
	rtnl_unlock();
	}

	void xenvif_disconnect(struct xenvif *vif)
	{
	if (netif_carrier_ok(vif->dev))
	xenvif_carrier_off(vif);

	if (vif->task) {
	kthread_stop(vif->task);
	vif->task = NULL;
	}

	if (vif->tx_irq) {
	if (vif->tx_irq == vif->rx_irq)
	unbind_from_irqhandler(vif->tx_irq, vif);
	else {
	unbind_from_irqhandler(vif->tx_irq, vif);
	unbind_from_irqhandler(vif->rx_irq, vif);
	}
	vif->tx_irq = 0;
	}

	xenvif_unmap_frontend_rings(vif);
	}

	void xenvif_free(struct xenvif *vif)
	{
	netif_napi_del(&vif->napi);

	unregister_netdev(vif->dev);

	vfree(vif->grant_copy_op);
	free_netdev(vif->dev);

	module_put(THIS_MODULE);
	}