/*
 * Copyright (C) 2017 - Cambridge Greys Limited
 * Copyright (C) 2011 - 2014 Cisco Systems Inc
 * Copyright (C) 2001 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
 * Copyright (C) 2001 Lennert Buytenhek (buytenh@gnu.org) and
 * James Leu (jleu@mindspring.net).
 * Copyright (C) 2001 by various other people who didn't put their name here.
 * Licensed under the GPL.
 */

#include <linux/version.h>
#include <linux/memblock.h>
#include <linux/etherdevice.h>
#include <linux/ethtool.h>
#include <linux/inetdevice.h>
#include <linux/init.h>
#include <linux/list.h>
#include <linux/netdevice.h>
#include <linux/platform_device.h>
#include <linux/rtnetlink.h>
#include <linux/skbuff.h>
#include <linux/slab.h>
#include <linux/interrupt.h>
#include <init.h>
#include <irq_kern.h>
#include <irq_user.h>
#include <net_kern.h>
#include <os.h>
#include "mconsole_kern.h"
#include "vector_user.h"
#include "vector_kern.h"

/*
 * Adapted from network devices with the following major changes:
 * All transports are static - simplifies the code significantly
 * Multiple FDs/IRQs per device
 * Vector IO optionally used for read/write, falling back to legacy
 * based on configuration and/or availability
 * Configuration is no longer positional - L2TPv3 and GRE require up to
 * 10 parameters, passing this as positional is not fit for purpose.
 * Only socket transports are supported
 */


#define DRIVER_NAME "uml-vector"
#define DRIVER_VERSION "01"
struct vector_cmd_line_arg {
        struct list_head list;
        int unit;
        char *arguments;
};

struct vector_device {
        struct list_head list;
        struct net_device *dev;
        struct platform_device pdev;
        int unit;
        int opened;
};

static LIST_HEAD(vec_cmd_line);

static DEFINE_SPINLOCK(vector_devices_lock);
static LIST_HEAD(vector_devices);

static int driver_registered;

static void vector_eth_configure(int n, struct arglist *def);

/* Argument accessors to set variables (and/or set default values)
 * mtu, buffer sizing, default headroom, etc
 */

#define DEFAULT_HEADROOM 2
#define SAFETY_MARGIN 32
#define DEFAULT_VECTOR_SIZE 64
#define TX_SMALL_PACKET 128
#define MAX_IOV_SIZE (MAX_SKB_FRAGS + 1)

static const struct {
        const char string[ETH_GSTRING_LEN];
} ethtool_stats_keys[] = {
        { "rx_queue_max" },
        { "rx_queue_running_average" },
        { "tx_queue_max" },
        { "tx_queue_running_average" },
        { "rx_encaps_errors" },
        { "tx_timeout_count" },
        { "tx_restart_queue" },
        { "tx_kicks" },
        { "tx_flow_control_xon" },
        { "tx_flow_control_xoff" },
        { "rx_csum_offload_good" },
        { "rx_csum_offload_errors"},
        { "sg_ok"},
        { "sg_linearized"},
};

#define VECTOR_NUM_STATS        ARRAY_SIZE(ethtool_stats_keys)

static void vector_reset_stats(struct vector_private *vp)
{
        vp->estats.rx_queue_max = 0;
        vp->estats.rx_queue_running_average = 0;
        vp->estats.tx_queue_max = 0;
        vp->estats.tx_queue_running_average = 0;
        vp->estats.rx_encaps_errors = 0;
        vp->estats.tx_timeout_count = 0;
        vp->estats.tx_restart_queue = 0;
        vp->estats.tx_kicks = 0;
        vp->estats.tx_flow_control_xon = 0;
        vp->estats.tx_flow_control_xoff = 0;
        vp->estats.sg_ok = 0;
        vp->estats.sg_linearized = 0;
}

static int get_mtu(struct arglist *def)
{
        char *mtu = uml_vector_fetch_arg(def, "mtu");
        long result;

        if (mtu != NULL) {
                if (kstrtoul(mtu, 10, &result) == 0)
                        return result;
        }
        return ETH_MAX_PACKET;
}

static int get_depth(struct arglist *def)
{
        char *mtu = uml_vector_fetch_arg(def, "depth");
        long result;

        if (mtu != NULL) {
                if (kstrtoul(mtu, 10, &result) == 0)
                        return result;
        }
        return DEFAULT_VECTOR_SIZE;
}

static int get_headroom(struct arglist *def)
{
        char *mtu = uml_vector_fetch_arg(def, "headroom");
        long result;

        if (mtu != NULL) {
                if (kstrtoul(mtu, 10, &result) == 0)
                        return result;
        }
        return DEFAULT_HEADROOM;
}

static int get_req_size(struct arglist *def)
{
        char *gro = uml_vector_fetch_arg(def, "gro");
        long result;

        if (gro != NULL) {
                if (kstrtoul(gro, 10, &result) == 0) {
                        if (result > 0)
                                return 65536;
                }
        }
        return get_mtu(def) + ETH_HEADER_OTHER +
                get_headroom(def) + SAFETY_MARGIN;
}


static int get_transport_options(struct arglist *def)
{
        char *transport = uml_vector_fetch_arg(def, "transport");
        char *vector = uml_vector_fetch_arg(def, "vec");

        int vec_rx = VECTOR_RX;
        int vec_tx = VECTOR_TX;
        long parsed;

        if (vector != NULL) {
                if (kstrtoul(vector, 10, &parsed) == 0) {
                        if (parsed == 0) {
                                vec_rx = 0;
                                vec_tx = 0;
                        }
                }
        }


        if (strncmp(transport, TRANS_TAP, TRANS_TAP_LEN) == 0)
                return (vec_rx | VECTOR_BPF);
        if (strncmp(transport, TRANS_RAW, TRANS_RAW_LEN) == 0)
                return (vec_rx | vec_tx | VECTOR_QDISC_BYPASS);
        return (vec_rx | vec_tx);
}


/* A mini-buffer for packet drop read
 * All of our supported transports are datagram oriented and we always
 * read using recvmsg or recvmmsg. If we pass a buffer which is smaller
 * than the packet size it still counts as full packet read and will
 * clean the incoming stream to keep sigio/epoll happy
 */

#define DROP_BUFFER_SIZE 32

static char *drop_buffer;

/* Array backed queues optimized for bulk enqueue/dequeue and
 * 1:N (small values of N) or 1:1 enqueuer/dequeuer ratios.
 * For more details and full design rationale see
 * http://foswiki.cambridgegreys.com/Main/EatYourTailAndEnjoyIt
 */


/*
 * Advance the mmsg queue head by n = advance. Resets the queue to
 * maximum enqueue/dequeue-at-once capacity if possible. Called by
 * dequeuers. Caller must hold the head_lock!
 */

static int vector_advancehead(struct vector_queue *qi, int advance)
{
        int queue_depth;

        qi->head =
                (qi->head + advance)
                        % qi->max_depth;


        spin_lock(&qi->tail_lock);
        qi->queue_depth -= advance;

        /* we are at 0, use this to
         * reset head and tail so we can use max size vectors
         */

        if (qi->queue_depth == 0) {
                qi->head = 0;
                qi->tail = 0;
        }
        queue_depth = qi->queue_depth;
        spin_unlock(&qi->tail_lock);
        return queue_depth;
}

/*      Advance the queue tail by n = advance.
 *      This is called by enqueuers which should hold the
 *      head lock already
 */

static int vector_advancetail(struct vector_queue *qi, int advance)
{
        int queue_depth;

        qi->tail =
                (qi->tail + advance)
                        % qi->max_depth;
        spin_lock(&qi->head_lock);
        qi->queue_depth += advance;
        queue_depth = qi->queue_depth;
        spin_unlock(&qi->head_lock);
        return queue_depth;
}

static int prep_msg(struct vector_private *vp,
        struct sk_buff *skb,
        struct iovec *iov)
{
        int iov_index = 0;
        int nr_frags, frag;
        skb_frag_t *skb_frag;

        nr_frags = skb_shinfo(skb)->nr_frags;
        if (nr_frags > MAX_IOV_SIZE) {
                if (skb_linearize(skb) != 0)
                        goto drop;
        }
        if (vp->header_size > 0) {
                iov[iov_index].iov_len = vp->header_size;
                vp->form_header(iov[iov_index].iov_base, skb, vp);
                iov_index++;
        }
        iov[iov_index].iov_base = skb->data;
        if (nr_frags > 0) {
                iov[iov_index].iov_len = skb->len - skb->data_len;
                vp->estats.sg_ok++;
        } else
                iov[iov_index].iov_len = skb->len;
        iov_index++;
        for (frag = 0; frag < nr_frags; frag++) {
                skb_frag = &skb_shinfo(skb)->frags[frag];
                iov[iov_index].iov_base = skb_frag_address_safe(skb_frag);
                iov[iov_index].iov_len = skb_frag_size(skb_frag);
                iov_index++;
        }
        return iov_index;
drop:
        return -1;
}
/*
 * Generic vector enqueue with support for forming headers using transport
 * specific callback. Allows GRE, L2TPv3, RAW and other transports
 * to use a common enqueue procedure in vector mode
 */

static int vector_enqueue(struct vector_queue *qi, struct sk_buff *skb)
{
        struct vector_private *vp = netdev_priv(qi->dev);
        int queue_depth;
        int packet_len;
        struct mmsghdr *mmsg_vector = qi->mmsg_vector;
        int iov_count;

        spin_lock(&qi->tail_lock);
        spin_lock(&qi->head_lock);
        queue_depth = qi->queue_depth;
        spin_unlock(&qi->head_lock);

        if (skb)
                packet_len = skb->len;

        if (queue_depth < qi->max_depth) {

                *(qi->skbuff_vector + qi->tail) = skb;
                mmsg_vector += qi->tail;
                iov_count = prep_msg(
                        vp,
                        skb,
                        mmsg_vector->msg_hdr.msg_iov
                );
                if (iov_count < 1)
                        goto drop;
                mmsg_vector->msg_hdr.msg_iovlen = iov_count;
                mmsg_vector->msg_hdr.msg_name = vp->fds->remote_addr;
                mmsg_vector->msg_hdr.msg_namelen = vp->fds->remote_addr_size;
                queue_depth = vector_advancetail(qi, 1);
        } else
                goto drop;
        spin_unlock(&qi->tail_lock);
        return queue_depth;
drop:
        qi->dev->stats.tx_dropped++;
        if (skb != NULL) {
                packet_len = skb->len;
                dev_consume_skb_any(skb);
                netdev_completed_queue(qi->dev, 1, packet_len);
        }
        spin_unlock(&qi->tail_lock);
        return queue_depth;
}

static int consume_vector_skbs(struct vector_queue *qi, int count)
{
        struct sk_buff *skb;
        int skb_index;
        int bytes_compl = 0;

        for (skb_index = qi->head; skb_index < qi->head + count; skb_index++) {
                skb = *(qi->skbuff_vector + skb_index);
                /* mark as empty to ensure correct destruction if
                 * needed
                 */
                bytes_compl += skb->len;
                *(qi->skbuff_vector + skb_index) = NULL;
                dev_consume_skb_any(skb);
        }
        qi->dev->stats.tx_bytes += bytes_compl;
        qi->dev->stats.tx_packets += count;
        netdev_completed_queue(qi->dev, count, bytes_compl);
        return vector_advancehead(qi, count);
}

/*
 * Generic vector deque via sendmmsg with support for forming headers
 * using transport specific callback. Allows GRE, L2TPv3, RAW and
 * other transports to use a common dequeue procedure in vector mode
 */


static int vector_send(struct vector_queue *qi)
{
        struct vector_private *vp = netdev_priv(qi->dev);
        struct mmsghdr *send_from;
        int result = 0, send_len, queue_depth = qi->max_depth;

        if (spin_trylock(&qi->head_lock)) {
                if (spin_trylock(&qi->tail_lock)) {
                        /* update queue_depth to current value */
                        queue_depth = qi->queue_depth;
                        spin_unlock(&qi->tail_lock);
                        while (queue_depth > 0) {
                                /* Calculate the start of the vector */
                                send_len = queue_depth;
                                send_from = qi->mmsg_vector;
                                send_from += qi->head;
                                /* Adjust vector size if wraparound */
                                if (send_len + qi->head > qi->max_depth)
                                        send_len = qi->max_depth - qi->head;
                                /* Try to TX as many packets as possible */
                                if (send_len > 0) {
                                        result = uml_vector_sendmmsg(
                                                 vp->fds->tx_fd,
                                                 send_from,
                                                 send_len,
                                                 0
                                        );
                                        vp->in_write_poll =
                                                (result != send_len);
                                }
                                /* For some of the sendmmsg error scenarios
                                 * we may end being unsure in the TX success
                                 * for all packets. It is safer to declare
                                 * them all TX-ed and blame the network.
                                 */
                                if (result < 0) {
                                        if (net_ratelimit())
                                                netdev_err(vp->dev, "sendmmsg err=%i\n",
                                                        result);
                                        result = send_len;
                                }
                                if (result > 0) {
                                        queue_depth =
                                                consume_vector_skbs(qi, result);
                                        /* This is equivalent to an TX IRQ.
                                         * Restart the upper layers to feed us
                                         * more packets.
                                         */
                                        if (result > vp->estats.tx_queue_max)
                                                vp->estats.tx_queue_max = result;
                                        vp->estats.tx_queue_running_average =
                                                (vp->estats.tx_queue_running_average + result) >> 1;
                                }
                                netif_trans_update(qi->dev);
                                netif_wake_queue(qi->dev);
                                /* if TX is busy, break out of the send loop,
                                 *  poll write IRQ will reschedule xmit for us
                                 */
                                if (result != send_len) {
                                        vp->estats.tx_restart_queue++;
                                        break;
                                }
                        }
                }
                spin_unlock(&qi->head_lock);
        } else {
                tasklet_schedule(&vp->tx_poll);
        }
        return queue_depth;
}

/* Queue destructor. Deliberately stateless so we can use
 * it in queue cleanup if initialization fails.
 */

static void destroy_queue(struct vector_queue *qi)
{
        int i;
        struct iovec *iov;
        struct vector_private *vp = netdev_priv(qi->dev);
        struct mmsghdr *mmsg_vector;

        if (qi == NULL)
                return;
        /* deallocate any skbuffs - we rely on any unused to be
         * set to NULL.
         */
        if (qi->skbuff_vector != NULL) {
                for (i = 0; i < qi->max_depth; i++) {
                        if (*(qi->skbuff_vector + i) != NULL)
                                dev_kfree_skb_any(*(qi->skbuff_vector + i));
                }
                kfree(qi->skbuff_vector);
        }
        /* deallocate matching IOV structures including header buffs */
        if (qi->mmsg_vector != NULL) {
                mmsg_vector = qi->mmsg_vector;
                for (i = 0; i < qi->max_depth; i++) {
                        iov = mmsg_vector->msg_hdr.msg_iov;
                        if (iov != NULL) {
                                if ((vp->header_size > 0) &&
                                        (iov->iov_base != NULL))
                                        kfree(iov->iov_base);
                                kfree(iov);
                        }
                        mmsg_vector++;
                }
                kfree(qi->mmsg_vector);
        }
        kfree(qi);
}

/*
 * Queue constructor. Create a queue with a given side.
 */
static struct vector_queue *create_queue(
        struct vector_private *vp,
        int max_size,
        int header_size,
        int num_extra_frags)
{
        struct vector_queue *result;
        int i;
        struct iovec *iov;
        struct mmsghdr *mmsg_vector;

        result = kmalloc(sizeof(struct vector_queue), GFP_KERNEL);
        if (result == NULL)
                return NULL;
        result->max_depth = max_size;
        result->dev = vp->dev;
        result->mmsg_vector = kmalloc(
                (sizeof(struct mmsghdr) * max_size), GFP_KERNEL);
        if (result->mmsg_vector == NULL)
                goto out_mmsg_fail;
        result->skbuff_vector = kmalloc(
                (sizeof(void *) * max_size), GFP_KERNEL);
        if (result->skbuff_vector == NULL)
                goto out_skb_fail;

        /* further failures can be handled safely by destroy_queue*/

        mmsg_vector = result->mmsg_vector;
        for (i = 0; i < max_size; i++) {
                /* Clear all pointers - we use non-NULL as marking on
                 * what to free on destruction
                 */
                *(result->skbuff_vector + i) = NULL;
                mmsg_vector->msg_hdr.msg_iov = NULL;
                mmsg_vector++;
        }
        mmsg_vector = result->mmsg_vector;
        result->max_iov_frags = num_extra_frags;
        for (i = 0; i < max_size; i++) {
                if (vp->header_size > 0)
                        iov = kmalloc_array(3 + num_extra_frags,
                                            sizeof(struct iovec),
                                            GFP_KERNEL
                        );
                else
                        iov = kmalloc_array(2 + num_extra_frags,
                                            sizeof(struct iovec),
                                            GFP_KERNEL
                        );
                if (iov == NULL)
                        goto out_fail;
                mmsg_vector->msg_hdr.msg_iov = iov;
                mmsg_vector->msg_hdr.msg_iovlen = 1;
                mmsg_vector->msg_hdr.msg_control = NULL;
                mmsg_vector->msg_hdr.msg_controllen = 0;
                mmsg_vector->msg_hdr.msg_flags = MSG_DONTWAIT;
                mmsg_vector->msg_hdr.msg_name = NULL;
                mmsg_vector->msg_hdr.msg_namelen = 0;
                if (vp->header_size > 0) {
                        iov->iov_base = kmalloc(header_size, GFP_KERNEL);
                        if (iov->iov_base == NULL)
                                goto out_fail;
                        iov->iov_len = header_size;
                        mmsg_vector->msg_hdr.msg_iovlen = 2;
                        iov++;
                }
                iov->iov_base = NULL;
                iov->iov_len = 0;
                mmsg_vector++;
        }
        spin_lock_init(&result->head_lock);
        spin_lock_init(&result->tail_lock);
        result->queue_depth = 0;
        result->head = 0;
        result->tail = 0;
        return result;
out_skb_fail:
        kfree(result->mmsg_vector);
out_mmsg_fail:
        kfree(result);
        return NULL;
out_fail:
        destroy_queue(result);
        return NULL;
}

/*
 * We do not use the RX queue as a proper wraparound queue for now
 * This is not necessary because the consumption via netif_rx()
 * happens in-line. While we can try using the return code of
 * netif_rx() for flow control there are no drivers doing this today.
 * For this RX specific use we ignore the tail/head locks and
 * just read into a prepared queue filled with skbuffs.
 */

static struct sk_buff *prep_skb(
        struct vector_private *vp,
        struct user_msghdr *msg)
{
        int linear = vp->max_packet + vp->headroom + SAFETY_MARGIN;
        struct sk_buff *result;
        int iov_index = 0, len;
        struct iovec *iov = msg->msg_iov;
        int err, nr_frags, frag;
        skb_frag_t *skb_frag;

        if (vp->req_size <= linear)
                len = linear;
        else
                len = vp->req_size;
        result = alloc_skb_with_frags(
                linear,
                len - vp->max_packet,
                3,
                &err,
                GFP_ATOMIC
        );
        if (vp->header_size > 0)
                iov_index++;
        if (result == NULL) {
                iov[iov_index].iov_base = NULL;
                iov[iov_index].iov_len = 0;
                goto done;
        }
        skb_reserve(result, vp->headroom);
        result->dev = vp->dev;
        skb_put(result, vp->max_packet);
        result->data_len = len - vp->max_packet;
        result->len += len - vp->max_packet;
        skb_reset_mac_header(result);
        result->ip_summed = CHECKSUM_NONE;
        iov[iov_index].iov_base = result->data;
        iov[iov_index].iov_len = vp->max_packet;
        iov_index++;

        nr_frags = skb_shinfo(result)->nr_frags;
        for (frag = 0; frag < nr_frags; frag++) {
                skb_frag = &skb_shinfo(result)->frags[frag];
                iov[iov_index].iov_base = skb_frag_address_safe(skb_frag);
                if (iov[iov_index].iov_base != NULL)
                        iov[iov_index].iov_len = skb_frag_size(skb_frag);
                else
                        iov[iov_index].iov_len = 0;
                iov_index++;
        }
done:
        msg->msg_iovlen = iov_index;
        return result;
}


/* Prepare queue for recvmmsg one-shot rx - fill with fresh sk_buffs*/

static void prep_queue_for_rx(struct vector_queue *qi)
{
        struct vector_private *vp = netdev_priv(qi->dev);
        struct mmsghdr *mmsg_vector = qi->mmsg_vector;
        void **skbuff_vector = qi->skbuff_vector;
        int i;

        if (qi->queue_depth == 0)
                return;
        for (i = 0; i < qi->queue_depth; i++) {
                /* it is OK if allocation fails - recvmmsg with NULL data in
                 * iov argument still performs an RX, just drops the packet
                 * This allows us stop faffing around with a "drop buffer"
                 */

                *skbuff_vector = prep_skb(vp, &mmsg_vector->msg_hdr);
                skbuff_vector++;
                mmsg_vector++;
        }
        qi->queue_depth = 0;
}

static struct vector_device *find_device(int n)
{
        struct vector_device *device;
        struct list_head *ele;

        spin_lock(&vector_devices_lock);
        list_for_each(ele, &vector_devices) {
                device = list_entry(ele, struct vector_device, list);
                if (device->unit == n)
                        goto out;
        }
        device = NULL;
 out:
        spin_unlock(&vector_devices_lock);
        return device;
}

static int vector_parse(char *str, int *index_out, char **str_out,
                        char **error_out)
{
        int n, len, err;
        char *start = str;

        len = strlen(str);

        while ((*str != ':') && (strlen(str) > 1))
                str++;
        if (*str != ':') {
                *error_out = "Expected ':' after device number";
                return -EINVAL;
        }
        *str = '\0';

        err = kstrtouint(start, 0, &n);
        if (err < 0) {
                *error_out = "Bad device number";
                return err;
        }

        str++;
        if (find_device(n)) {
                *error_out = "Device already configured";
                return -EINVAL;
        }

        *index_out = n;
        *str_out = str;
        return 0;
}

static int vector_config(char *str, char **error_out)
{
        int err, n;
        char *params;
        struct arglist *parsed;

        err = vector_parse(str, &n, &params, error_out);
        if (err != 0)
                return err;

        /* This string is broken up and the pieces used by the underlying
         * driver. We should copy it to make sure things do not go wrong
         * later.
         */

        params = kstrdup(params, GFP_KERNEL);
        if (params == NULL) {
                *error_out = "vector_config failed to strdup string";
                return -ENOMEM;
        }

        parsed = uml_parse_vector_ifspec(params);

        if (parsed == NULL) {
                *error_out = "vector_config failed to parse parameters";
                return -EINVAL;
        }

        vector_eth_configure(n, parsed);
        return 0;
}

static int vector_id(char **str, int *start_out, int *end_out)
{
        char *end;
        int n;

        n = simple_strtoul(*str, &end, 0);
        if ((*end != '\0') || (end == *str))
                return -1;

        *start_out = n;
        *end_out = n;
        *str = end;
        return n;
}

static int vector_remove(int n, char **error_out)
{
        struct vector_device *vec_d;
        struct net_device *dev;
        struct vector_private *vp;

        vec_d = find_device(n);
        if (vec_d == NULL)
                return -ENODEV;
        dev = vec_d->dev;
        vp = netdev_priv(dev);
        if (vp->fds != NULL)
                return -EBUSY;
        unregister_netdev(dev);
        platform_device_unregister(&vec_d->pdev);
        return 0;
}

/*
 * There is no shared per-transport initialization code, so
 * we will just initialize each interface one by one and
 * add them to a list
 */

static struct platform_driver uml_net_driver = {
        .driver = {
                .name = DRIVER_NAME,
        },
};


static void vector_device_release(struct device *dev)
{
        struct vector_device *device = dev_get_drvdata(dev);
        struct net_device *netdev = device->dev;

        list_del(&device->list);
        kfree(device);
        free_netdev(netdev);
}

/* Bog standard recv using recvmsg - not used normally unless the user
 * explicitly specifies not to use recvmmsg vector RX.
 */

static int vector_legacy_rx(struct vector_private *vp)
{
        int pkt_len;
        struct user_msghdr hdr;
        struct iovec iov[2 + MAX_IOV_SIZE]; /* header + data use case only */
        int iovpos = 0;
        struct sk_buff *skb;
        int header_check;

        hdr.msg_name = NULL;
        hdr.msg_namelen = 0;
        hdr.msg_iov = (struct iovec *) &iov;
        hdr.msg_control = NULL;
        hdr.msg_controllen = 0;
        hdr.msg_flags = 0;

        if (vp->header_size > 0) {
                iov[0].iov_base = vp->header_rxbuffer;
                iov[0].iov_len = vp->header_size;
        }

        skb = prep_skb(vp, &hdr);

        if (skb == NULL) {
                /* Read a packet into drop_buffer and don't do
                 * anything with it.
                 */
                iov[iovpos].iov_base = drop_buffer;
                iov[iovpos].iov_len = DROP_BUFFER_SIZE;
                hdr.msg_iovlen = 1;
                vp->dev->stats.rx_dropped++;
        }

        pkt_len = uml_vector_recvmsg(vp->fds->rx_fd, &hdr, 0);

        if (skb != NULL) {
                if (pkt_len > vp->header_size) {
                        if (vp->header_size > 0) {
                                header_check = vp->verify_header(
                                        vp->header_rxbuffer, skb, vp);
                                if (header_check < 0) {
                                        dev_kfree_skb_irq(skb);
                                        vp->dev->stats.rx_dropped++;
                                        vp->estats.rx_encaps_errors++;
                                        return 0;
                                }
                                if (header_check > 0) {
                                        vp->estats.rx_csum_offload_good++;
                                        skb->ip_summed = CHECKSUM_UNNECESSARY;
                                }
                        }
                        pskb_trim(skb, pkt_len - vp->rx_header_size);
                        skb->protocol = eth_type_trans(skb, skb->dev);
                        vp->dev->stats.rx_bytes += skb->len;
                        vp->dev->stats.rx_packets++;
                        netif_rx(skb);
                } else {
                        dev_kfree_skb_irq(skb);
                }
        }
        return pkt_len;
}

/*
 * Packet at a time TX which falls back to vector TX if the
 * underlying transport is busy.
 */



static int writev_tx(struct vector_private *vp, struct sk_buff *skb)
{
        struct iovec iov[3 + MAX_IOV_SIZE];
        int iov_count, pkt_len = 0;

        iov[0].iov_base = vp->header_txbuffer;
        iov_count = prep_msg(vp, skb, (struct iovec *) &iov);

        if (iov_count < 1)
                goto drop;
        pkt_len = uml_vector_writev(
                vp->fds->tx_fd,
                (struct iovec *) &iov,
                iov_count
        );

        netif_trans_update(vp->dev);
        netif_wake_queue(vp->dev);

        if (pkt_len > 0) {
                vp->dev->stats.tx_bytes += skb->len;
                vp->dev->stats.tx_packets++;
        } else {
                vp->dev->stats.tx_dropped++;
        }
        consume_skb(skb);
        return pkt_len;
drop:
        vp->dev->stats.tx_dropped++;
        consume_skb(skb);
        return pkt_len;
}

/*
 * Receive as many messages as we can in one call using the special
 * mmsg vector matched to an skb vector which we prepared earlier.
 */

static int vector_mmsg_rx(struct vector_private *vp)
{
        int packet_count, i;
        struct vector_queue *qi = vp->rx_queue;
        struct sk_buff *skb;
        struct mmsghdr *mmsg_vector = qi->mmsg_vector;
        void **skbuff_vector = qi->skbuff_vector;
        int header_check;

        /* Refresh the vector and make sure it is with new skbs and the
         * iovs are updated to point to them.
         */

        prep_queue_for_rx(qi);

        /* Fire the Lazy Gun - get as many packets as we can in one go. */

        packet_count = uml_vector_recvmmsg(
                vp->fds->rx_fd, qi->mmsg_vector, qi->max_depth, 0);

        if (packet_count <= 0)
                return packet_count;

        /* We treat packet processing as enqueue, buffer refresh as dequeue
         * The queue_depth tells us how many buffers have been used and how
         * many do we need to prep the next time prep_queue_for_rx() is called.
         */

        qi->queue_depth = packet_count;

        for (i = 0; i < packet_count; i++) {
                skb = (*skbuff_vector);
                if (mmsg_vector->msg_len > vp->header_size) {
                        if (vp->header_size > 0) {
                                header_check = vp->verify_header(
                                        mmsg_vector->msg_hdr.msg_iov->iov_base,
                                        skb,
                                        vp
                                );
                                if (header_check < 0) {
                                /* Overlay header failed to verify - discard.
                                 * We can actually keep this skb and reuse it,
                                 * but that will make the prep logic too
                                 * complex.
                                 */
                                        dev_kfree_skb_irq(skb);
                                        vp->estats.rx_encaps_errors++;
                                        continue;
                                }
                                if (header_check > 0) {
                                        vp->estats.rx_csum_offload_good++;
                                        skb->ip_summed = CHECKSUM_UNNECESSARY;
                                }
                        }
                        pskb_trim(skb,
                                mmsg_vector->msg_len - vp->rx_header_size);
                        skb->protocol = eth_type_trans(skb, skb->dev);
                        /*
                         * We do not need to lock on updating stats here
                         * The interrupt loop is non-reentrant.
                         */
                        vp->dev->stats.rx_bytes += skb->len;
                        vp->dev->stats.rx_packets++;
                        netif_rx(skb);
                } else {
                        /* Overlay header too short to do anything - discard.
                         * We can actually keep this skb and reuse it,
                         * but that will make the prep logic too complex.
                         */
                        if (skb != NULL)
                                dev_kfree_skb_irq(skb);
                }
                (*skbuff_vector) = NULL;
                /* Move to the next buffer element */
                mmsg_vector++;
                skbuff_vector++;
        }
        if (packet_count > 0) {
                if (vp->estats.rx_queue_max < packet_count)
                        vp->estats.rx_queue_max = packet_count;
                vp->estats.rx_queue_running_average =
                        (vp->estats.rx_queue_running_average + packet_count) >> 1;

        }
        return packet_count;
}

static void vector_rx(struct vector_private *vp)
{
        int err;

        if ((vp->options & VECTOR_RX) > 0)
                while ((err = vector_mmsg_rx(vp)) > 0)
                        ;
        else
                while ((err = vector_legacy_rx(vp)) > 0)
                        ;
        if ((err != 0) && net_ratelimit())
                netdev_err(vp->dev, "vector_rx: error(%d)\n", err);
}

static int vector_net_start_xmit(struct sk_buff *skb, struct net_device *dev)
{
        struct vector_private *vp = netdev_priv(dev);
        int queue_depth = 0;

        if ((vp->options & VECTOR_TX) == 0) {
                writev_tx(vp, skb);
                return NETDEV_TX_OK;
        }

        /* We do BQL only in the vector path, no point doing it in
         * packet at a time mode as there is no device queue
         */

        netdev_sent_queue(vp->dev, skb->len);
        queue_depth = vector_enqueue(vp->tx_queue, skb);

        /* if the device queue is full, stop the upper layers and
         * flush it.
         */

        if (queue_depth >= vp->tx_queue->max_depth - 1) {
                vp->estats.tx_kicks++;
                netif_stop_queue(dev);
                vector_send(vp->tx_queue);
                return NETDEV_TX_OK;
        }
        if (netdev_xmit_more()) {
                mod_timer(&vp->tl, vp->coalesce);
                return NETDEV_TX_OK;
        }
        if (skb->len < TX_SMALL_PACKET) {
                vp->estats.tx_kicks++;
                vector_send(vp->tx_queue);
        } else
                tasklet_schedule(&vp->tx_poll);
        return NETDEV_TX_OK;
}

static irqreturn_t vector_rx_interrupt(int irq, void *dev_id)
{
        struct net_device *dev = dev_id;
        struct vector_private *vp = netdev_priv(dev);

        if (!netif_running(dev))
                return IRQ_NONE;
        vector_rx(vp);
        return IRQ_HANDLED;

}

static irqreturn_t vector_tx_interrupt(int irq, void *dev_id)
{
        struct net_device *dev = dev_id;
        struct vector_private *vp = netdev_priv(dev);

        if (!netif_running(dev))
                return IRQ_NONE;
        /* We need to pay attention to it only if we got
         * -EAGAIN or -ENOBUFFS from sendmmsg. Otherwise
         * we ignore it. In the future, it may be worth
         * it to improve the IRQ controller a bit to make
         * tweaking the IRQ mask less costly
         */

        if (vp->in_write_poll)
                tasklet_schedule(&vp->tx_poll);
        return IRQ_HANDLED;

}

static int irq_rr;

static int vector_net_close(struct net_device *dev)
{
        struct vector_private *vp = netdev_priv(dev);
        unsigned long flags;

        netif_stop_queue(dev);
        del_timer(&vp->tl);

        if (vp->fds == NULL)
                return 0;

        /* Disable and free all IRQS */
        if (vp->rx_irq > 0) {
                um_free_irq(vp->rx_irq, dev);
                vp->rx_irq = 0;
        }
        if (vp->tx_irq > 0) {
                um_free_irq(vp->tx_irq, dev);
                vp->tx_irq = 0;
        }
        tasklet_kill(&vp->tx_poll);
        if (vp->fds->rx_fd > 0) {
                os_close_file(vp->fds->rx_fd);
                vp->fds->rx_fd = -1;
        }
        if (vp->fds->tx_fd > 0) {
                os_close_file(vp->fds->tx_fd);
                vp->fds->tx_fd = -1;
        }
        kfree(vp->bpf);
        kfree(vp->fds->remote_addr);
        kfree(vp->transport_data);
        kfree(vp->header_rxbuffer);
        kfree(vp->header_txbuffer);
        if (vp->rx_queue != NULL)
                destroy_queue(vp->rx_queue);
        if (vp->tx_queue != NULL)
                destroy_queue(vp->tx_queue);
        kfree(vp->fds);
        vp->fds = NULL;
        spin_lock_irqsave(&vp->lock, flags);
        vp->opened = false;
        spin_unlock_irqrestore(&vp->lock, flags);
        return 0;
}

/* TX tasklet */

static void vector_tx_poll(unsigned long data)
{
        struct vector_private *vp = (struct vector_private *)data;

        vp->estats.tx_kicks++;
        vector_send(vp->tx_queue);
}
static void vector_reset_tx(struct work_struct *work)
{
        struct vector_private *vp =
                container_of(work, struct vector_private, reset_tx);
        netdev_reset_queue(vp->dev);
        netif_start_queue(vp->dev);
        netif_wake_queue(vp->dev);
}
static int vector_net_open(struct net_device *dev)
{
        struct vector_private *vp = netdev_priv(dev);
        unsigned long flags;
        int err = -EINVAL;
        struct vector_device *vdevice;

        spin_lock_irqsave(&vp->lock, flags);
        if (vp->opened) {
                spin_unlock_irqrestore(&vp->lock, flags);
                return -ENXIO;
        }
        vp->opened = true;
        spin_unlock_irqrestore(&vp->lock, flags);

        vp->fds = uml_vector_user_open(vp->unit, vp->parsed);

        if (vp->fds == NULL)
                goto out_close;

        if (build_transport_data(vp) < 0)
                goto out_close;

        if ((vp->options & VECTOR_RX) > 0) {
                vp->rx_queue = create_queue(
                        vp,
                        get_depth(vp->parsed),
                        vp->rx_header_size,
                        MAX_IOV_SIZE
                );
                vp->rx_queue->queue_depth = get_depth(vp->parsed);
        } else {
                vp->header_rxbuffer = kmalloc(
                        vp->rx_header_size,
                        GFP_KERNEL
                );
                if (vp->header_rxbuffer == NULL)
                        goto out_close;
        }
        if ((vp->options & VECTOR_TX) > 0) {
                vp->tx_queue = create_queue(
                        vp,
                        get_depth(vp->parsed),
                        vp->header_size,
                        MAX_IOV_SIZE
                );
        } else {
                vp->header_txbuffer = kmalloc(vp->header_size, GFP_KERNEL);
                if (vp->header_txbuffer == NULL)
                        goto out_close;
        }

        /* READ IRQ */
        err = um_request_irq(
                irq_rr + VECTOR_BASE_IRQ, vp->fds->rx_fd,
                        IRQ_READ, vector_rx_interrupt,
                        IRQF_SHARED, dev->name, dev);
        if (err != 0) {
                netdev_err(dev, "vector_open: failed to get rx irq(%d)\n", err);
                err = -ENETUNREACH;
                goto out_close;
        }
        vp->rx_irq = irq_rr + VECTOR_BASE_IRQ;
        dev->irq = irq_rr + VECTOR_BASE_IRQ;
        irq_rr = (irq_rr + 1) % VECTOR_IRQ_SPACE;

        /* WRITE IRQ - we need it only if we have vector TX */
        if ((vp->options & VECTOR_TX) > 0) {
                err = um_request_irq(
                        irq_rr + VECTOR_BASE_IRQ, vp->fds->tx_fd,
                                IRQ_WRITE, vector_tx_interrupt,
                                IRQF_SHARED, dev->name, dev);
                if (err != 0) {
                        netdev_err(dev,
                                "vector_open: failed to get tx irq(%d)\n", err);
                        err = -ENETUNREACH;
                        goto out_close;
                }
                vp->tx_irq = irq_rr + VECTOR_BASE_IRQ;
                irq_rr = (irq_rr + 1) % VECTOR_IRQ_SPACE;
        }

        if ((vp->options & VECTOR_QDISC_BYPASS) != 0) {
                if (!uml_raw_enable_qdisc_bypass(vp->fds->rx_fd))
                        vp->options |= VECTOR_BPF;
        }
        if ((vp->options & VECTOR_BPF) != 0)
                vp->bpf = uml_vector_default_bpf(vp->fds->rx_fd, dev->dev_addr);

        netif_start_queue(dev);

        /* clear buffer - it can happen that the host side of the interface
         * is full when we get here. In this case, new data is never queued,
         * SIGIOs never arrive, and the net never works.
         */

        vector_rx(vp);

        vector_reset_stats(vp);
        vdevice = find_device(vp->unit);
        vdevice->opened = 1;

        if ((vp->options & VECTOR_TX) != 0)
                add_timer(&vp->tl);
        return 0;
out_close:
        vector_net_close(dev);
        return err;
}


static void vector_net_set_multicast_list(struct net_device *dev)
{
        /* TODO: - we can do some BPF games here */
        return;
}

static void vector_net_tx_timeout(struct net_device *dev)
{
        struct vector_private *vp = netdev_priv(dev);

        vp->estats.tx_timeout_count++;
        netif_trans_update(dev);
        schedule_work(&vp->reset_tx);
}

static netdev_features_t vector_fix_features(struct net_device *dev,
        netdev_features_t features)
{
        features &= ~(NETIF_F_IP_CSUM|NETIF_F_IPV6_CSUM);
        return features;
}

static int vector_set_features(struct net_device *dev,
        netdev_features_t features)
{
        struct vector_private *vp = netdev_priv(dev);
        /* Adjust buffer sizes for GSO/GRO. Unfortunately, there is
         * no way to negotiate it on raw sockets, so we can change
         * only our side.
         */
        if (features & NETIF_F_GRO)
                /* All new frame buffers will be GRO-sized */
                vp->req_size = 65536;
        else
                /* All new frame buffers will be normal sized */
                vp->req_size = vp->max_packet + vp->headroom + SAFETY_MARGIN;
        return 0;
}

#ifdef CONFIG_NET_POLL_CONTROLLER
static void vector_net_poll_controller(struct net_device *dev)
{
        disable_irq(dev->irq);
        vector_rx_interrupt(dev->irq, dev);
        enable_irq(dev->irq);
}
#endif

static void vector_net_get_drvinfo(struct net_device *dev,
                                struct ethtool_drvinfo *info)
{
        strlcpy(info->driver, DRIVER_NAME, sizeof(info->driver));
        strlcpy(info->version, DRIVER_VERSION, sizeof(info->version));
}

static void vector_get_ringparam(struct net_device *netdev,
                                struct ethtool_ringparam *ring)
{
        struct vector_private *vp = netdev_priv(netdev);

        ring->rx_max_pending = vp->rx_queue->max_depth;
        ring->tx_max_pending = vp->tx_queue->max_depth;
        ring->rx_pending = vp->rx_queue->max_depth;
        ring->tx_pending = vp->tx_queue->max_depth;
}

static void vector_get_strings(struct net_device *dev, u32 stringset, u8 *buf)
{
        switch (stringset) {
        case ETH_SS_TEST:
                *buf = '\0';
                break;
        case ETH_SS_STATS:
                memcpy(buf, &ethtool_stats_keys, sizeof(ethtool_stats_keys));
                break;
        default:
                WARN_ON(1);
                break;
        }
}

static int vector_get_sset_count(struct net_device *dev, int sset)
{
        switch (sset) {
        case ETH_SS_TEST:
                return 0;
        case ETH_SS_STATS:
                return VECTOR_NUM_STATS;
        default:
                return -EOPNOTSUPP;
        }
}

static void vector_get_ethtool_stats(struct net_device *dev,
        struct ethtool_stats *estats,
        u64 *tmp_stats)
{
        struct vector_private *vp = netdev_priv(dev);

        memcpy(tmp_stats, &vp->estats, sizeof(struct vector_estats));
}

static int vector_get_coalesce(struct net_device *netdev,
                                        struct ethtool_coalesce *ec)
{
        struct vector_private *vp = netdev_priv(netdev);

        ec->tx_coalesce_usecs = (vp->coalesce * 1000000) / HZ;
        return 0;
}

static int vector_set_coalesce(struct net_device *netdev,
                                        struct ethtool_coalesce *ec)
{
        struct vector_private *vp = netdev_priv(netdev);

        vp->coalesce = (ec->tx_coalesce_usecs * HZ) / 1000000;
        if (vp->coalesce == 0)
                vp->coalesce = 1;
        return 0;
}

static const struct ethtool_ops vector_net_ethtool_ops = {
        .get_drvinfo    = vector_net_get_drvinfo,
        .get_link       = ethtool_op_get_link,
        .get_ts_info    = ethtool_op_get_ts_info,
        .get_ringparam  = vector_get_ringparam,
        .get_strings    = vector_get_strings,
        .get_sset_count = vector_get_sset_count,
        .get_ethtool_stats = vector_get_ethtool_stats,
        .get_coalesce   = vector_get_coalesce,
        .set_coalesce   = vector_set_coalesce,
};


static const struct net_device_ops vector_netdev_ops = {
        .ndo_open               = vector_net_open,
        .ndo_stop               = vector_net_close,
        .ndo_start_xmit         = vector_net_start_xmit,
        .ndo_set_rx_mode        = vector_net_set_multicast_list,
        .ndo_tx_timeout         = vector_net_tx_timeout,
        .ndo_set_mac_address    = eth_mac_addr,
        .ndo_validate_addr      = eth_validate_addr,
        .ndo_fix_features       = vector_fix_features,
        .ndo_set_features       = vector_set_features,
#ifdef CONFIG_NET_POLL_CONTROLLER
        .ndo_poll_controller = vector_net_poll_controller,
#endif
};


static void vector_timer_expire(struct timer_list *t)
{
        struct vector_private *vp = from_timer(vp, t, tl);

        vp->estats.tx_kicks++;
        vector_send(vp->tx_queue);
}

static void vector_eth_configure(
                int n,
                struct arglist *def
        )
{
        struct vector_device *device;
        struct net_device *dev;
        struct vector_private *vp;
        int err;

        device = kzalloc(sizeof(*device), GFP_KERNEL);
        if (device == NULL) {
                printk(KERN_ERR "eth_configure failed to allocate struct "
                                 "vector_device\n");
                return;
        }
        dev = alloc_etherdev(sizeof(struct vector_private));
        if (dev == NULL) {
                printk(KERN_ERR "eth_configure: failed to allocate struct "
                                 "net_device for vec%d\n", n);
                goto out_free_device;
        }

        dev->mtu = get_mtu(def);

        INIT_LIST_HEAD(&device->list);
        device->unit = n;

        /* If this name ends up conflicting with an existing registered
         * netdevice, that is OK, register_netdev{,ice}() will notice this
         * and fail.
         */
        snprintf(dev->name, sizeof(dev->name), "vec%d", n);
        uml_net_setup_etheraddr(dev, uml_vector_fetch_arg(def, "mac"));
        vp = netdev_priv(dev);

        /* sysfs register */
        if (!driver_registered) {
                platform_driver_register(&uml_net_driver);
                driver_registered = 1;
        }
        device->pdev.id = n;
        device->pdev.name = DRIVER_NAME;
        device->pdev.dev.release = vector_device_release;
        dev_set_drvdata(&device->pdev.dev, device);
        if (platform_device_register(&device->pdev))
                goto out_free_netdev;
        SET_NETDEV_DEV(dev, &device->pdev.dev);

        device->dev = dev;

        *vp = ((struct vector_private)
                {
                .list                   = LIST_HEAD_INIT(vp->list),
                .dev                    = dev,
                .unit                   = n,
                .options                = get_transport_options(def),
                .rx_irq                 = 0,
                .tx_irq                 = 0,
                .parsed                 = def,
                .max_packet             = get_mtu(def) + ETH_HEADER_OTHER,
                /* TODO - we need to calculate headroom so that ip header
                 * is 16 byte aligned all the time
                 */
                .headroom               = get_headroom(def),
                .form_header            = NULL,
                .verify_header          = NULL,
                .header_rxbuffer        = NULL,
                .header_txbuffer        = NULL,
                .header_size            = 0,
                .rx_header_size         = 0,
                .rexmit_scheduled       = false,
                .opened                 = false,
                .transport_data         = NULL,
                .in_write_poll          = false,
                .coalesce               = 2,
                .req_size               = get_req_size(def)
                });

        dev->features = dev->hw_features = (NETIF_F_SG | NETIF_F_FRAGLIST);
        tasklet_init(&vp->tx_poll, vector_tx_poll, (unsigned long)vp);
        INIT_WORK(&vp->reset_tx, vector_reset_tx);

        timer_setup(&vp->tl, vector_timer_expire, 0);
        spin_lock_init(&vp->lock);

        /* FIXME */
        dev->netdev_ops = &vector_netdev_ops;
        dev->ethtool_ops = &vector_net_ethtool_ops;
        dev->watchdog_timeo = (HZ >> 1);
        /* primary IRQ - fixme */
        dev->irq = 0; /* we will adjust this once opened */

        rtnl_lock();
        err = register_netdevice(dev);
        rtnl_unlock();
        if (err)
                goto out_undo_user_init;

        spin_lock(&vector_devices_lock);
        list_add(&device->list, &vector_devices);
        spin_unlock(&vector_devices_lock);

        return;

out_undo_user_init:
        return;
out_free_netdev:
        free_netdev(dev);
out_free_device:
        kfree(device);
}




/*
 * Invoked late in the init
 */

static int __init vector_init(void)
{
        struct list_head *ele;
        struct vector_cmd_line_arg *def;
        struct arglist *parsed;

        list_for_each(ele, &vec_cmd_line) {
                def = list_entry(ele, struct vector_cmd_line_arg, list);
                parsed = uml_parse_vector_ifspec(def->arguments);
                if (parsed != NULL)
                        vector_eth_configure(def->unit, parsed);
        }
        return 0;
}


/* Invoked at initial argument parsing, only stores
 * arguments until a proper vector_init is called
 * later
 */

static int __init vector_setup(char *str)
{
        char *error;
        int n, err;
        struct vector_cmd_line_arg *new;

        err = vector_parse(str, &n, &str, &error);
        if (err) {
                printk(KERN_ERR "vector_setup - Couldn't parse '%s' : %s\n",
                                 str, error);
                return 1;
        }
        new = memblock_alloc(sizeof(*new), SMP_CACHE_BYTES);
        if (!new)
                panic("%s: Failed to allocate %zu bytes\n", __func__,
                      sizeof(*new));
        INIT_LIST_HEAD(&new->list);
        new->unit = n;
        new->arguments = str;
        list_add_tail(&new->list, &vec_cmd_line);
        return 1;
}

__setup("vec", vector_setup);
__uml_help(vector_setup,
"vec[0-9]+:<option>=<value>,<option>=<value>\n"
"        Configure a vector io network device.\n\n"
);

late_initcall(vector_init);

static struct mc_device vector_mc = {
        .list           = LIST_HEAD_INIT(vector_mc.list),
        .name           = "vec",
        .config         = vector_config,
        .get_config     = NULL,
        .id             = vector_id,
        .remove         = vector_remove,
};

#ifdef CONFIG_INET
static int vector_inetaddr_event(
        struct notifier_block *this,
        unsigned long event,
        void *ptr)
{
        return NOTIFY_DONE;
}

static struct notifier_block vector_inetaddr_notifier = {
        .notifier_call          = vector_inetaddr_event,
};

static void inet_register(void)
{
        register_inetaddr_notifier(&vector_inetaddr_notifier);
}
#else
static inline void inet_register(void)
{
}
#endif

static int vector_net_init(void)
{
        mconsole_register_dev(&vector_mc);
        inet_register();
        return 0;
}

__initcall(vector_net_init);