Merge commit 'origin/master' into next

[deliverable/linux.git] / drivers / net / virtio_net.c

/* A simple network driver using virtio.
 *
 * Copyright 2007 Rusty Russell <rusty@rustcorp.com.au> IBM Corporation
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */
//#define DEBUG
#include <linux/netdevice.h>
#include <linux/etherdevice.h>
#include <linux/ethtool.h>
#include <linux/module.h>
#include <linux/virtio.h>
#include <linux/virtio_net.h>
#include <linux/scatterlist.h>
#include <linux/if_vlan.h>

static int napi_weight = 128;
module_param(napi_weight, int, 0444);

static int csum = 1, gso = 1;
module_param(csum, bool, 0444);
module_param(gso, bool, 0444);

/* FIXME: MTU in config. */
#define MAX_PACKET_LEN (ETH_HLEN + VLAN_HLEN + ETH_DATA_LEN)
#define GOOD_COPY_LEN   128

struct virtnet_info
{
        struct virtio_device *vdev;
        struct virtqueue *rvq, *svq;
        struct net_device *dev;
        struct napi_struct napi;

        /* The skb we couldn't send because buffers were full. */
        struct sk_buff *last_xmit_skb;

        /* If we need to free in a timer, this is it. */
        struct timer_list xmit_free_timer;

        /* Number of input buffers, and max we've ever had. */
        unsigned int num, max;

        /* For cleaning up after transmission. */
        struct tasklet_struct tasklet;
        bool free_in_tasklet;

        /* I like... big packets and I cannot lie! */
        bool big_packets;

        /* Host will merge rx buffers for big packets (shake it! shake it!) */
        bool mergeable_rx_bufs;

        /* Receive & send queues. */
        struct sk_buff_head recv;
        struct sk_buff_head send;

        /* Chain pages by the private ptr. */
        struct page *pages;
};

static inline void *skb_vnet_hdr(struct sk_buff *skb)
{
        return (struct virtio_net_hdr *)skb->cb;
}

static void give_a_page(struct virtnet_info *vi, struct page *page)
{
        page->private = (unsigned long)vi->pages;
        vi->pages = page;
}

static void trim_pages(struct virtnet_info *vi, struct sk_buff *skb)
{
        unsigned int i;

        for (i = 0; i < skb_shinfo(skb)->nr_frags; i++)
                give_a_page(vi, skb_shinfo(skb)->frags[i].page);
        skb_shinfo(skb)->nr_frags = 0;
        skb->data_len = 0;
}

static struct page *get_a_page(struct virtnet_info *vi, gfp_t gfp_mask)
{
        struct page *p = vi->pages;

        if (p)
                vi->pages = (struct page *)p->private;
        else
                p = alloc_page(gfp_mask);
        return p;
}

static void skb_xmit_done(struct virtqueue *svq)
{
        struct virtnet_info *vi = svq->vdev->priv;

        /* Suppress further interrupts. */
        svq->vq_ops->disable_cb(svq);

        /* We were probably waiting for more output buffers. */
        netif_wake_queue(vi->dev);

        /* Make sure we re-xmit last_xmit_skb: if there are no more packets
         * queued, start_xmit won't be called. */
        tasklet_schedule(&vi->tasklet);
}

static void receive_skb(struct net_device *dev, struct sk_buff *skb,
                        unsigned len)
{
        struct virtnet_info *vi = netdev_priv(dev);
        struct virtio_net_hdr *hdr = skb_vnet_hdr(skb);
        int err;
        int i;

        if (unlikely(len < sizeof(struct virtio_net_hdr) + ETH_HLEN)) {
                pr_debug("%s: short packet %i\n", dev->name, len);
                dev->stats.rx_length_errors++;
                goto drop;
        }

        if (vi->mergeable_rx_bufs) {
                struct virtio_net_hdr_mrg_rxbuf *mhdr = skb_vnet_hdr(skb);
                unsigned int copy;
                char *p = page_address(skb_shinfo(skb)->frags[0].page);

                if (len > PAGE_SIZE)
                        len = PAGE_SIZE;
                len -= sizeof(struct virtio_net_hdr_mrg_rxbuf);

                memcpy(hdr, p, sizeof(*mhdr));
                p += sizeof(*mhdr);

                copy = len;
                if (copy > skb_tailroom(skb))
                        copy = skb_tailroom(skb);

                memcpy(skb_put(skb, copy), p, copy);

                len -= copy;

                if (!len) {
                        give_a_page(vi, skb_shinfo(skb)->frags[0].page);
                        skb_shinfo(skb)->nr_frags--;
                } else {
                        skb_shinfo(skb)->frags[0].page_offset +=
                                sizeof(*mhdr) + copy;
                        skb_shinfo(skb)->frags[0].size = len;
                        skb->data_len += len;
                        skb->len += len;
                }

                while (--mhdr->num_buffers) {
                        struct sk_buff *nskb;

                        i = skb_shinfo(skb)->nr_frags;
                        if (i >= MAX_SKB_FRAGS) {
                                pr_debug("%s: packet too long %d\n", dev->name,
                                         len);
                                dev->stats.rx_length_errors++;
                                goto drop;
                        }

                        nskb = vi->rvq->vq_ops->get_buf(vi->rvq, &len);
                        if (!nskb) {
                                pr_debug("%s: rx error: %d buffers missing\n",
                                         dev->name, mhdr->num_buffers);
                                dev->stats.rx_length_errors++;
                                goto drop;
                        }

                        __skb_unlink(nskb, &vi->recv);
                        vi->num--;

                        skb_shinfo(skb)->frags[i] = skb_shinfo(nskb)->frags[0];
                        skb_shinfo(nskb)->nr_frags = 0;
                        kfree_skb(nskb);

                        if (len > PAGE_SIZE)
                                len = PAGE_SIZE;

                        skb_shinfo(skb)->frags[i].size = len;
                        skb_shinfo(skb)->nr_frags++;
                        skb->data_len += len;
                        skb->len += len;
                }
        } else {
                len -= sizeof(struct virtio_net_hdr);

                if (len <= MAX_PACKET_LEN)
                        trim_pages(vi, skb);

                err = pskb_trim(skb, len);
                if (err) {
                        pr_debug("%s: pskb_trim failed %i %d\n", dev->name,
                                 len, err);
                        dev->stats.rx_dropped++;
                        goto drop;
                }
        }

        skb->truesize += skb->data_len;
        dev->stats.rx_bytes += skb->len;
        dev->stats.rx_packets++;

        if (hdr->flags & VIRTIO_NET_HDR_F_NEEDS_CSUM) {
                pr_debug("Needs csum!\n");
                if (!skb_partial_csum_set(skb,hdr->csum_start,hdr->csum_offset))
                        goto frame_err;
        }

        skb->protocol = eth_type_trans(skb, dev);
        pr_debug("Receiving skb proto 0x%04x len %i type %i\n",
                 ntohs(skb->protocol), skb->len, skb->pkt_type);

        if (hdr->gso_type != VIRTIO_NET_HDR_GSO_NONE) {
                pr_debug("GSO!\n");
                switch (hdr->gso_type & ~VIRTIO_NET_HDR_GSO_ECN) {
                case VIRTIO_NET_HDR_GSO_TCPV4:
                        skb_shinfo(skb)->gso_type = SKB_GSO_TCPV4;
                        break;
                case VIRTIO_NET_HDR_GSO_UDP:
                        skb_shinfo(skb)->gso_type = SKB_GSO_UDP;
                        break;
                case VIRTIO_NET_HDR_GSO_TCPV6:
                        skb_shinfo(skb)->gso_type = SKB_GSO_TCPV6;
                        break;
                default:
                        if (net_ratelimit())
                                printk(KERN_WARNING "%s: bad gso type %u.\n",
                                       dev->name, hdr->gso_type);
                        goto frame_err;
                }

                if (hdr->gso_type & VIRTIO_NET_HDR_GSO_ECN)
                        skb_shinfo(skb)->gso_type |= SKB_GSO_TCP_ECN;

                skb_shinfo(skb)->gso_size = hdr->gso_size;
                if (skb_shinfo(skb)->gso_size == 0) {
                        if (net_ratelimit())
                                printk(KERN_WARNING "%s: zero gso size.\n",
                                       dev->name);
                        goto frame_err;
                }

                /* Header must be checked, and gso_segs computed. */
                skb_shinfo(skb)->gso_type |= SKB_GSO_DODGY;
                skb_shinfo(skb)->gso_segs = 0;
        }

        netif_receive_skb(skb);
        return;

frame_err:
        dev->stats.rx_frame_errors++;
drop:
        dev_kfree_skb(skb);
}

static void try_fill_recv_maxbufs(struct virtnet_info *vi)
{
        struct sk_buff *skb;
        struct scatterlist sg[2+MAX_SKB_FRAGS];
        int num, err, i;

        sg_init_table(sg, 2+MAX_SKB_FRAGS);
        for (;;) {
                struct virtio_net_hdr *hdr;

                skb = netdev_alloc_skb(vi->dev, MAX_PACKET_LEN);
                if (unlikely(!skb))
                        break;

                skb_put(skb, MAX_PACKET_LEN);

                hdr = skb_vnet_hdr(skb);
                sg_set_buf(sg, hdr, sizeof(*hdr));

                if (vi->big_packets) {
                        for (i = 0; i < MAX_SKB_FRAGS; i++) {
                                skb_frag_t *f = &skb_shinfo(skb)->frags[i];
                                f->page = get_a_page(vi, GFP_ATOMIC);
                                if (!f->page)
                                        break;

                                f->page_offset = 0;
                                f->size = PAGE_SIZE;

                                skb->data_len += PAGE_SIZE;
                                skb->len += PAGE_SIZE;

                                skb_shinfo(skb)->nr_frags++;
                        }
                }

                num = skb_to_sgvec(skb, sg+1, 0, skb->len) + 1;
                skb_queue_head(&vi->recv, skb);

                err = vi->rvq->vq_ops->add_buf(vi->rvq, sg, 0, num, skb);
                if (err) {
                        skb_unlink(skb, &vi->recv);
                        trim_pages(vi, skb);
                        kfree_skb(skb);
                        break;
                }
                vi->num++;
        }
        if (unlikely(vi->num > vi->max))
                vi->max = vi->num;
        vi->rvq->vq_ops->kick(vi->rvq);
}

static void try_fill_recv(struct virtnet_info *vi)
{
        struct sk_buff *skb;
        struct scatterlist sg[1];
        int err;

        if (!vi->mergeable_rx_bufs) {
                try_fill_recv_maxbufs(vi);
                return;
        }

        for (;;) {
                skb_frag_t *f;

                skb = netdev_alloc_skb(vi->dev, GOOD_COPY_LEN + NET_IP_ALIGN);
                if (unlikely(!skb))
                        break;

                skb_reserve(skb, NET_IP_ALIGN);

                f = &skb_shinfo(skb)->frags[0];
                f->page = get_a_page(vi, GFP_ATOMIC);
                if (!f->page) {
                        kfree_skb(skb);
                        break;
                }

                f->page_offset = 0;
                f->size = PAGE_SIZE;

                skb_shinfo(skb)->nr_frags++;

                sg_init_one(sg, page_address(f->page), PAGE_SIZE);
                skb_queue_head(&vi->recv, skb);

                err = vi->rvq->vq_ops->add_buf(vi->rvq, sg, 0, 1, skb);
                if (err) {
                        skb_unlink(skb, &vi->recv);
                        kfree_skb(skb);
                        break;
                }
                vi->num++;
        }
        if (unlikely(vi->num > vi->max))
                vi->max = vi->num;
        vi->rvq->vq_ops->kick(vi->rvq);
}

static void skb_recv_done(struct virtqueue *rvq)
{
        struct virtnet_info *vi = rvq->vdev->priv;
        /* Schedule NAPI, Suppress further interrupts if successful. */
        if (netif_rx_schedule_prep(&vi->napi)) {
                rvq->vq_ops->disable_cb(rvq);
                __netif_rx_schedule(&vi->napi);
        }
}

static int virtnet_poll(struct napi_struct *napi, int budget)
{
        struct virtnet_info *vi = container_of(napi, struct virtnet_info, napi);
        struct sk_buff *skb = NULL;
        unsigned int len, received = 0;

again:
        while (received < budget &&
               (skb = vi->rvq->vq_ops->get_buf(vi->rvq, &len)) != NULL) {
                __skb_unlink(skb, &vi->recv);
                receive_skb(vi->dev, skb, len);
                vi->num--;
                received++;
        }

        /* FIXME: If we oom and completely run out of inbufs, we need
         * to start a timer trying to fill more. */
        if (vi->num < vi->max / 2)
                try_fill_recv(vi);

        /* Out of packets? */
        if (received < budget) {
                netif_rx_complete(napi);
                if (unlikely(!vi->rvq->vq_ops->enable_cb(vi->rvq))
                    && napi_schedule_prep(napi)) {
                        vi->rvq->vq_ops->disable_cb(vi->rvq);
                        __netif_rx_schedule(napi);
                        goto again;
                }
        }

        return received;
}

static void free_old_xmit_skbs(struct virtnet_info *vi)
{
        struct sk_buff *skb;
        unsigned int len;

        while ((skb = vi->svq->vq_ops->get_buf(vi->svq, &len)) != NULL) {
                pr_debug("Sent skb %p\n", skb);
                __skb_unlink(skb, &vi->send);
                vi->dev->stats.tx_bytes += skb->len;
                vi->dev->stats.tx_packets++;
                kfree_skb(skb);
        }
}

/* If the virtio transport doesn't always notify us when all in-flight packets
 * are consumed, we fall back to using this function on a timer to free them. */
static void xmit_free(unsigned long data)
{
        struct virtnet_info *vi = (void *)data;

        netif_tx_lock(vi->dev);

        free_old_xmit_skbs(vi);

        if (!skb_queue_empty(&vi->send))
                mod_timer(&vi->xmit_free_timer, jiffies + (HZ/10));

        netif_tx_unlock(vi->dev);
}

static int xmit_skb(struct virtnet_info *vi, struct sk_buff *skb)
{
        int num, err;
        struct scatterlist sg[2+MAX_SKB_FRAGS];
        struct virtio_net_hdr_mrg_rxbuf *mhdr = skb_vnet_hdr(skb);
        struct virtio_net_hdr *hdr = skb_vnet_hdr(skb);
        const unsigned char *dest = ((struct ethhdr *)skb->data)->h_dest;

        sg_init_table(sg, 2+MAX_SKB_FRAGS);

        pr_debug("%s: xmit %p %pM\n", vi->dev->name, skb, dest);

        if (skb->ip_summed == CHECKSUM_PARTIAL) {
                hdr->flags = VIRTIO_NET_HDR_F_NEEDS_CSUM;
                hdr->csum_start = skb->csum_start - skb_headroom(skb);
                hdr->csum_offset = skb->csum_offset;
        } else {
                hdr->flags = 0;
                hdr->csum_offset = hdr->csum_start = 0;
        }

        if (skb_is_gso(skb)) {
                hdr->hdr_len = skb_transport_header(skb) - skb->data;
                hdr->gso_size = skb_shinfo(skb)->gso_size;
                if (skb_shinfo(skb)->gso_type & SKB_GSO_TCPV4)
                        hdr->gso_type = VIRTIO_NET_HDR_GSO_TCPV4;
                else if (skb_shinfo(skb)->gso_type & SKB_GSO_TCPV6)
                        hdr->gso_type = VIRTIO_NET_HDR_GSO_TCPV6;
                else if (skb_shinfo(skb)->gso_type & SKB_GSO_UDP)
                        hdr->gso_type = VIRTIO_NET_HDR_GSO_UDP;
                else
                        BUG();
                if (skb_shinfo(skb)->gso_type & SKB_GSO_TCP_ECN)
                        hdr->gso_type |= VIRTIO_NET_HDR_GSO_ECN;
        } else {
                hdr->gso_type = VIRTIO_NET_HDR_GSO_NONE;
                hdr->gso_size = hdr->hdr_len = 0;
        }

        mhdr->num_buffers = 0;

        /* Encode metadata header at front. */
        if (vi->mergeable_rx_bufs)
                sg_set_buf(sg, mhdr, sizeof(*mhdr));
        else
                sg_set_buf(sg, hdr, sizeof(*hdr));

        num = skb_to_sgvec(skb, sg+1, 0, skb->len) + 1;

        err = vi->svq->vq_ops->add_buf(vi->svq, sg, num, 0, skb);
        if (!err && !vi->free_in_tasklet)
                mod_timer(&vi->xmit_free_timer, jiffies + (HZ/10));

        return err;
}

static void xmit_tasklet(unsigned long data)
{
        struct virtnet_info *vi = (void *)data;

        netif_tx_lock_bh(vi->dev);
        if (vi->last_xmit_skb && xmit_skb(vi, vi->last_xmit_skb) == 0) {
                vi->svq->vq_ops->kick(vi->svq);
                vi->last_xmit_skb = NULL;
        }
        if (vi->free_in_tasklet)
                free_old_xmit_skbs(vi);
        netif_tx_unlock_bh(vi->dev);
}

static int start_xmit(struct sk_buff *skb, struct net_device *dev)
{
        struct virtnet_info *vi = netdev_priv(dev);

again:
        /* Free up any pending old buffers before queueing new ones. */
        free_old_xmit_skbs(vi);

        /* If we has a buffer left over from last time, send it now. */
        if (unlikely(vi->last_xmit_skb) &&
            xmit_skb(vi, vi->last_xmit_skb) != 0)
                goto stop_queue;

        vi->last_xmit_skb = NULL;

        /* Put new one in send queue and do transmit */
        if (likely(skb)) {
                __skb_queue_head(&vi->send, skb);
                if (xmit_skb(vi, skb) != 0) {
                        vi->last_xmit_skb = skb;
                        skb = NULL;
                        goto stop_queue;
                }
        }
done:
        vi->svq->vq_ops->kick(vi->svq);
        return NETDEV_TX_OK;

stop_queue:
        pr_debug("%s: virtio not prepared to send\n", dev->name);
        netif_stop_queue(dev);

        /* Activate callback for using skbs: if this returns false it
         * means some were used in the meantime. */
        if (unlikely(!vi->svq->vq_ops->enable_cb(vi->svq))) {
                vi->svq->vq_ops->disable_cb(vi->svq);
                netif_start_queue(dev);
                goto again;
        }
        if (skb) {
                /* Drop this skb: we only queue one. */
                vi->dev->stats.tx_dropped++;
                kfree_skb(skb);
        }
        goto done;
}

#ifdef CONFIG_NET_POLL_CONTROLLER
static void virtnet_netpoll(struct net_device *dev)
{
        struct virtnet_info *vi = netdev_priv(dev);

        napi_schedule(&vi->napi);
}
#endif

static int virtnet_open(struct net_device *dev)
{
        struct virtnet_info *vi = netdev_priv(dev);

        napi_enable(&vi->napi);

        /* If all buffers were filled by other side before we napi_enabled, we
         * won't get another interrupt, so process any outstanding packets
         * now.  virtnet_poll wants re-enable the queue, so we disable here.
         * We synchronize against interrupts via NAPI_STATE_SCHED */
        if (netif_rx_schedule_prep(&vi->napi)) {
                vi->rvq->vq_ops->disable_cb(vi->rvq);
                __netif_rx_schedule(&vi->napi);
        }
        return 0;
}

static int virtnet_close(struct net_device *dev)
{
        struct virtnet_info *vi = netdev_priv(dev);

        napi_disable(&vi->napi);

        return 0;
}

static int virtnet_set_tx_csum(struct net_device *dev, u32 data)
{
        struct virtnet_info *vi = netdev_priv(dev);
        struct virtio_device *vdev = vi->vdev;

        if (data && !virtio_has_feature(vdev, VIRTIO_NET_F_CSUM))
                return -ENOSYS;

        return ethtool_op_set_tx_hw_csum(dev, data);
}

static struct ethtool_ops virtnet_ethtool_ops = {
        .set_tx_csum = virtnet_set_tx_csum,
        .set_sg = ethtool_op_set_sg,
        .set_tso = ethtool_op_set_tso,
        .get_link = ethtool_op_get_link,
};

#define MIN_MTU 68
#define MAX_MTU 65535

static int virtnet_change_mtu(struct net_device *dev, int new_mtu)
{
        if (new_mtu < MIN_MTU || new_mtu > MAX_MTU)
                return -EINVAL;
        dev->mtu = new_mtu;
        return 0;
}

static const struct net_device_ops virtnet_netdev = {
        .ndo_open            = virtnet_open,
        .ndo_stop            = virtnet_close,
        .ndo_start_xmit      = start_xmit,
        .ndo_validate_addr   = eth_validate_addr,
        .ndo_set_mac_address = eth_mac_addr,
        .ndo_change_mtu      = virtnet_change_mtu,
#ifdef CONFIG_NET_POLL_CONTROLLER
        .ndo_poll_controller = virtnet_netpoll,
#endif
};

static int virtnet_probe(struct virtio_device *vdev)
{
        int err;
        struct net_device *dev;
        struct virtnet_info *vi;

        /* Allocate ourselves a network device with room for our info */
        dev = alloc_etherdev(sizeof(struct virtnet_info));
        if (!dev)
                return -ENOMEM;

        /* Set up network device as normal. */
        dev->netdev_ops = &virtnet_netdev;
        dev->features = NETIF_F_HIGHDMA;
        SET_ETHTOOL_OPS(dev, &virtnet_ethtool_ops);
        SET_NETDEV_DEV(dev, &vdev->dev);

        /* Do we support "hardware" checksums? */
        if (csum && virtio_has_feature(vdev, VIRTIO_NET_F_CSUM)) {
                /* This opens up the world of extra features. */
                dev->features |= NETIF_F_HW_CSUM|NETIF_F_SG|NETIF_F_FRAGLIST;
                if (gso && virtio_has_feature(vdev, VIRTIO_NET_F_GSO)) {
                        dev->features |= NETIF_F_TSO | NETIF_F_UFO
                                | NETIF_F_TSO_ECN | NETIF_F_TSO6;
                }
                /* Individual feature bits: what can host handle? */
                if (gso && virtio_has_feature(vdev, VIRTIO_NET_F_HOST_TSO4))
                        dev->features |= NETIF_F_TSO;
                if (gso && virtio_has_feature(vdev, VIRTIO_NET_F_HOST_TSO6))
                        dev->features |= NETIF_F_TSO6;
                if (gso && virtio_has_feature(vdev, VIRTIO_NET_F_HOST_ECN))
                        dev->features |= NETIF_F_TSO_ECN;
                if (gso && virtio_has_feature(vdev, VIRTIO_NET_F_HOST_UFO))
                        dev->features |= NETIF_F_UFO;
        }

        /* Configuration may specify what MAC to use.  Otherwise random. */
        if (virtio_has_feature(vdev, VIRTIO_NET_F_MAC)) {
                vdev->config->get(vdev,
                                  offsetof(struct virtio_net_config, mac),
                                  dev->dev_addr, dev->addr_len);
        } else
                random_ether_addr(dev->dev_addr);

        /* Set up our device-specific information */
        vi = netdev_priv(dev);
        netif_napi_add(dev, &vi->napi, virtnet_poll, napi_weight);
        vi->dev = dev;
        vi->vdev = vdev;
        vdev->priv = vi;
        vi->pages = NULL;

        /* If they give us a callback when all buffers are done, we don't need
         * the timer. */
        vi->free_in_tasklet = virtio_has_feature(vdev,VIRTIO_F_NOTIFY_ON_EMPTY);

        /* If we can receive ANY GSO packets, we must allocate large ones. */
        if (virtio_has_feature(vdev, VIRTIO_NET_F_GUEST_TSO4)
            || virtio_has_feature(vdev, VIRTIO_NET_F_GUEST_TSO6)
            || virtio_has_feature(vdev, VIRTIO_NET_F_GUEST_ECN))
                vi->big_packets = true;

        if (virtio_has_feature(vdev, VIRTIO_NET_F_MRG_RXBUF))
                vi->mergeable_rx_bufs = true;

        /* We expect two virtqueues, receive then send. */
        vi->rvq = vdev->config->find_vq(vdev, 0, skb_recv_done);
        if (IS_ERR(vi->rvq)) {
                err = PTR_ERR(vi->rvq);
                goto free;
        }

        vi->svq = vdev->config->find_vq(vdev, 1, skb_xmit_done);
        if (IS_ERR(vi->svq)) {
                err = PTR_ERR(vi->svq);
                goto free_recv;
        }

        /* Initialize our empty receive and send queues. */
        skb_queue_head_init(&vi->recv);
        skb_queue_head_init(&vi->send);

        tasklet_init(&vi->tasklet, xmit_tasklet, (unsigned long)vi);

        if (!vi->free_in_tasklet)
                setup_timer(&vi->xmit_free_timer, xmit_free, (unsigned long)vi);

        err = register_netdev(dev);
        if (err) {
                pr_debug("virtio_net: registering device failed\n");
                goto free_send;
        }

        /* Last of all, set up some receive buffers. */
        try_fill_recv(vi);

        /* If we didn't even get one input buffer, we're useless. */
        if (vi->num == 0) {
                err = -ENOMEM;
                goto unregister;
        }

        netif_carrier_on(dev);

        pr_debug("virtnet: registered device %s\n", dev->name);
        return 0;

unregister:
        unregister_netdev(dev);
free_send:
        vdev->config->del_vq(vi->svq);
free_recv:
        vdev->config->del_vq(vi->rvq);
free:
        free_netdev(dev);
        return err;
}

static void virtnet_remove(struct virtio_device *vdev)
{
        struct virtnet_info *vi = vdev->priv;
        struct sk_buff *skb;

        /* Stop all the virtqueues. */
        vdev->config->reset(vdev);

        if (!vi->free_in_tasklet)
                del_timer_sync(&vi->xmit_free_timer);

        /* Free our skbs in send and recv queues, if any. */
        while ((skb = __skb_dequeue(&vi->recv)) != NULL) {
                kfree_skb(skb);
                vi->num--;
        }
        __skb_queue_purge(&vi->send);

        BUG_ON(vi->num != 0);

        vdev->config->del_vq(vi->svq);
        vdev->config->del_vq(vi->rvq);
        unregister_netdev(vi->dev);

        while (vi->pages)
                __free_pages(get_a_page(vi, GFP_KERNEL), 0);

        free_netdev(vi->dev);
}

static struct virtio_device_id id_table[] = {
        { VIRTIO_ID_NET, VIRTIO_DEV_ANY_ID },
        { 0 },
};

static unsigned int features[] = {
        VIRTIO_NET_F_CSUM, VIRTIO_NET_F_GUEST_CSUM,
        VIRTIO_NET_F_GSO, VIRTIO_NET_F_MAC,
        VIRTIO_NET_F_HOST_TSO4, VIRTIO_NET_F_HOST_UFO, VIRTIO_NET_F_HOST_TSO6,
        VIRTIO_NET_F_HOST_ECN, VIRTIO_NET_F_GUEST_TSO4, VIRTIO_NET_F_GUEST_TSO6,
        VIRTIO_NET_F_GUEST_ECN, /* We don't yet handle UFO input. */
        VIRTIO_NET_F_MRG_RXBUF,
        VIRTIO_F_NOTIFY_ON_EMPTY,
};

static struct virtio_driver virtio_net = {
        .feature_table = features,
        .feature_table_size = ARRAY_SIZE(features),
        .driver.name =  KBUILD_MODNAME,
        .driver.owner = THIS_MODULE,
        .id_table =     id_table,
        .probe =        virtnet_probe,
        .remove =       __devexit_p(virtnet_remove),
};

static int __init init(void)
{
        return register_virtio_driver(&virtio_net);
}

static void __exit fini(void)
{
        unregister_virtio_driver(&virtio_net);
}
module_init(init);
module_exit(fini);

MODULE_DEVICE_TABLE(virtio, id_table);
MODULE_DESCRIPTION("Virtio network driver");
MODULE_LICENSE("GPL");