netvsc.c

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/*
 * Copyright (c) 2009, Microsoft Corporation.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms and conditions of the GNU General Public License,
 * version 2, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope 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.
 *
 * Authors:
 *   Haiyang Zhang <[email protected]>
 *   Hank Janssen  <[email protected]>
 */
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/wait.h>
#include <linux/mm.h>
#include <linux/delay.h>
#include <linux/io.h>
#include <linux/slab.h>
#include <linux/netdevice.h>
#include <linux/if_ether.h>

#include "hyperv_net.h"


static struct netvsc_device *alloc_net_device(struct hv_device *device)
{
    struct netvsc_device *net_device;
    struct net_device *ndev = hv_get_drvdata(device);

    net_device = kzalloc(sizeof(struct netvsc_device), GFP_KERNEL);
    if (!net_device)
        return NULL;

    init_waitqueue_head(&net_device->wait_drain);
    net_device->start_remove = false;
    net_device->destroy = false;
    net_device->dev = device;
    net_device->ndev = ndev;

    hv_set_drvdata(device, net_device);
    return net_device;
}

static struct netvsc_device *get_outbound_net_device(struct hv_device *device)
{
    struct netvsc_device *net_device;

    net_device = hv_get_drvdata(device);
    if (net_device && net_device->destroy)
        net_device = NULL;

    return net_device;
}

static struct netvsc_device *get_inbound_net_device(struct hv_device *device)
{
    struct netvsc_device *net_device;

    net_device = hv_get_drvdata(device);

    if (!net_device)
        goto get_in_err;

    if (net_device->destroy &&
        atomic_read(&net_device->num_outstanding_sends) == 0)
        net_device = NULL;

get_in_err:
    return net_device;
}


static int netvsc_destroy_recv_buf(struct netvsc_device *net_device)
{
    struct nvsp_message *revoke_packet;
    int ret = 0;
    struct net_device *ndev = net_device->ndev;

    /*
     * If we got a section count, it means we received a
     * SendReceiveBufferComplete msg (ie sent
     * NvspMessage1TypeSendReceiveBuffer msg) therefore, we need
     * to send a revoke msg here
     */
    if (net_device->recv_section_cnt) {
        /* Send the revoke receive buffer */
        revoke_packet = &net_device->revoke_packet;
        memset(revoke_packet, 0, sizeof(struct nvsp_message));

        revoke_packet->hdr.msg_type =
            NVSP_MSG1_TYPE_REVOKE_RECV_BUF;
        revoke_packet->msg.v1_msg.
        revoke_recv_buf.id = NETVSC_RECEIVE_BUFFER_ID;

        ret = vmbus_sendpacket(net_device->dev->channel,
                       revoke_packet,
                       sizeof(struct nvsp_message),
                       (unsigned long)revoke_packet,
                       VM_PKT_DATA_INBAND, 0);
        /*
         * If we failed here, we might as well return and
         * have a leak rather than continue and a bugchk
         */
        if (ret != 0) {
            netdev_err(ndev, "unable to send "
                "revoke receive buffer to netvsp\n");
            return ret;
        }
    }

    /* Teardown the gpadl on the vsp end */
    if (net_device->recv_buf_gpadl_handle) {
        ret = vmbus_teardown_gpadl(net_device->dev->channel,
               net_device->recv_buf_gpadl_handle);

        /* If we failed here, we might as well return and have a leak
         * rather than continue and a bugchk
         */
        if (ret != 0) {
            netdev_err(ndev,
                   "unable to teardown receive buffer's gpadl\n");
            return ret;
        }
        net_device->recv_buf_gpadl_handle = 0;
    }

    if (net_device->recv_buf) {
        /* Free up the receive buffer */
        free_pages((unsigned long)net_device->recv_buf,
            get_order(net_device->recv_buf_size));
        net_device->recv_buf = NULL;
    }

    if (net_device->recv_section) {
        net_device->recv_section_cnt = 0;
        kfree(net_device->recv_section);
        net_device->recv_section = NULL;
    }

    return ret;
}

static int netvsc_init_recv_buf(struct hv_device *device)
{
    int ret = 0;
    int t;
    struct netvsc_device *net_device;
    struct nvsp_message *init_packet;
    struct net_device *ndev;

    net_device = get_outbound_net_device(device);
    if (!net_device)
        return -ENODEV;
    ndev = net_device->ndev;

    net_device->recv_buf =
        (void *)__get_free_pages(GFP_KERNEL|__GFP_ZERO,
                get_order(net_device->recv_buf_size));
    if (!net_device->recv_buf) {
        netdev_err(ndev, "unable to allocate receive "
            "buffer of size %d\n", net_device->recv_buf_size);
        ret = -ENOMEM;
        goto cleanup;
    }

    /*
     * Establish the gpadl handle for this buffer on this
     * channel.  Note: This call uses the vmbus connection rather
     * than the channel to establish the gpadl handle.
     */
    ret = vmbus_establish_gpadl(device->channel, net_device->recv_buf,
                    net_device->recv_buf_size,
                    &net_device->recv_buf_gpadl_handle);
    if (ret != 0) {
        netdev_err(ndev,
            "unable to establish receive buffer's gpadl\n");
        goto cleanup;
    }


    /* Notify the NetVsp of the gpadl handle */
    init_packet = &net_device->channel_init_pkt;

    memset(init_packet, 0, sizeof(struct nvsp_message));

    init_packet->hdr.msg_type = NVSP_MSG1_TYPE_SEND_RECV_BUF;
    init_packet->msg.v1_msg.send_recv_buf.
        gpadl_handle = net_device->recv_buf_gpadl_handle;
    init_packet->msg.v1_msg.
        send_recv_buf.id = NETVSC_RECEIVE_BUFFER_ID;

    /* Send the gpadl notification request */
    ret = vmbus_sendpacket(device->channel, init_packet,
                   sizeof(struct nvsp_message),
                   (unsigned long)init_packet,
                   VM_PKT_DATA_INBAND,
                   VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
    if (ret != 0) {
        netdev_err(ndev,
            "unable to send receive buffer's gpadl to netvsp\n");
        goto cleanup;
    }

    t = wait_for_completion_timeout(&net_device->channel_init_wait, 5*HZ);
    BUG_ON(t == 0);


    /* Check the response */
    if (init_packet->msg.v1_msg.
        send_recv_buf_complete.status != NVSP_STAT_SUCCESS) {
        netdev_err(ndev, "Unable to complete receive buffer "
               "initialization with NetVsp - status %d\n",
               init_packet->msg.v1_msg.
               send_recv_buf_complete.status);
        ret = -EINVAL;
        goto cleanup;
    }

    /* Parse the response */

    net_device->recv_section_cnt = init_packet->msg.
        v1_msg.send_recv_buf_complete.num_sections;

    net_device->recv_section = kmemdup(
        init_packet->msg.v1_msg.send_recv_buf_complete.sections,
        net_device->recv_section_cnt *
        sizeof(struct nvsp_1_receive_buffer_section),
        GFP_KERNEL);
    if (net_device->recv_section == NULL) {
        ret = -EINVAL;
        goto cleanup;
    }

    /*
     * For 1st release, there should only be 1 section that represents the
     * entire receive buffer
     */
    if (net_device->recv_section_cnt != 1 ||
        net_device->recv_section->offset != 0) {
        ret = -EINVAL;
        goto cleanup;
    }

    goto exit;

cleanup:
    netvsc_destroy_recv_buf(net_device);

exit:
    return ret;
}


/* Negotiate NVSP protocol version */
static int negotiate_nvsp_ver(struct hv_device *device,
                  struct netvsc_device *net_device,
                  struct nvsp_message *init_packet,
                  u32 nvsp_ver)
{
    int ret, t;

    memset(init_packet, 0, sizeof(struct nvsp_message));
    init_packet->hdr.msg_type = NVSP_MSG_TYPE_INIT;
    init_packet->msg.init_msg.init.min_protocol_ver = nvsp_ver;
    init_packet->msg.init_msg.init.max_protocol_ver = nvsp_ver;

    /* Send the init request */
    ret = vmbus_sendpacket(device->channel, init_packet,
                   sizeof(struct nvsp_message),
                   (unsigned long)init_packet,
                   VM_PKT_DATA_INBAND,
                   VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);

    if (ret != 0)
        return ret;

    t = wait_for_completion_timeout(&net_device->channel_init_wait, 5*HZ);

    if (t == 0)
        return -ETIMEDOUT;

    if (init_packet->msg.init_msg.init_complete.status !=
        NVSP_STAT_SUCCESS)
        return -EINVAL;

    if (nvsp_ver != NVSP_PROTOCOL_VERSION_2)
        return 0;

    /* NVSPv2 only: Send NDIS config */
    memset(init_packet, 0, sizeof(struct nvsp_message));
    init_packet->hdr.msg_type = NVSP_MSG2_TYPE_SEND_NDIS_CONFIG;
    init_packet->msg.v2_msg.send_ndis_config.mtu = net_device->ndev->mtu;
    init_packet->msg.v2_msg.send_ndis_config.capability.ieee8021q = 1;

    ret = vmbus_sendpacket(device->channel, init_packet,
                sizeof(struct nvsp_message),
                (unsigned long)init_packet,
                VM_PKT_DATA_INBAND, 0);

    return ret;
}

static int netvsc_connect_vsp(struct hv_device *device)
{
    int ret;
    struct netvsc_device *net_device;
    struct nvsp_message *init_packet;
    int ndis_version;
    struct net_device *ndev;

    net_device = get_outbound_net_device(device);
    if (!net_device)
        return -ENODEV;
    ndev = net_device->ndev;

    init_packet = &net_device->channel_init_pkt;

    /* Negotiate the latest NVSP protocol supported */
    if (negotiate_nvsp_ver(device, net_device, init_packet,
                   NVSP_PROTOCOL_VERSION_2) == 0) {
        net_device->nvsp_version = NVSP_PROTOCOL_VERSION_2;
    } else if (negotiate_nvsp_ver(device, net_device, init_packet,
                    NVSP_PROTOCOL_VERSION_1) == 0) {
        net_device->nvsp_version = NVSP_PROTOCOL_VERSION_1;
    } else {
        ret = -EPROTO;
        goto cleanup;
    }

    pr_debug("Negotiated NVSP version:%x\n", net_device->nvsp_version);

    /* Send the ndis version */
    memset(init_packet, 0, sizeof(struct nvsp_message));

    ndis_version = 0x00050001;

    init_packet->hdr.msg_type = NVSP_MSG1_TYPE_SEND_NDIS_VER;
    init_packet->msg.v1_msg.
        send_ndis_ver.ndis_major_ver =
                (ndis_version & 0xFFFF0000) >> 16;
    init_packet->msg.v1_msg.
        send_ndis_ver.ndis_minor_ver =
                ndis_version & 0xFFFF;

    /* Send the init request */
    ret = vmbus_sendpacket(device->channel, init_packet,
                sizeof(struct nvsp_message),
                (unsigned long)init_packet,
                VM_PKT_DATA_INBAND, 0);
    if (ret != 0)
        goto cleanup;

    /* Post the big receive buffer to NetVSP */
    ret = netvsc_init_recv_buf(device);

cleanup:
    return ret;
}

static void netvsc_disconnect_vsp(struct netvsc_device *net_device)
{
    netvsc_destroy_recv_buf(net_device);
}

/*
 * netvsc_device_remove - Callback when the root bus device is removed
 */
int netvsc_device_remove(struct hv_device *device)
{
    struct netvsc_device *net_device;
    struct hv_netvsc_packet *netvsc_packet, *pos;
    unsigned long flags;

    net_device = hv_get_drvdata(device);

    netvsc_disconnect_vsp(net_device);

    /*
     * Since we have already drained, we don't need to busy wait
     * as was done in final_release_stor_device()
     * Note that we cannot set the ext pointer to NULL until
     * we have drained - to drain the outgoing packets, we need to
     * allow incoming packets.
     */

    spin_lock_irqsave(&device->channel->inbound_lock, flags);
    hv_set_drvdata(device, NULL);
    spin_unlock_irqrestore(&device->channel->inbound_lock, flags);

    /*
     * At this point, no one should be accessing net_device
     * except in here
     */
    dev_notice(&device->device, "net device safe to remove\n");

    /* Now, we can close the channel safely */
    vmbus_close(device->channel);

    /* Release all resources */
    list_for_each_entry_safe(netvsc_packet, pos,
                 &net_device->recv_pkt_list, list_ent) {
        list_del(&netvsc_packet->list_ent);
        kfree(netvsc_packet);
    }

    kfree(net_device);
    return 0;
}


#define RING_AVAIL_PERCENT_HIWATER 20
#define RING_AVAIL_PERCENT_LOWATER 10

/*
 * Get the percentage of available bytes to write in the ring.
 * The return value is in range from 0 to 100.
 */
static inline u32 hv_ringbuf_avail_percent(
        struct hv_ring_buffer_info *ring_info)
{
    u32 avail_read, avail_write;

    hv_get_ringbuffer_availbytes(ring_info, &avail_read, &avail_write);

    return avail_write * 100 / ring_info->ring_datasize;
}

static void netvsc_send_completion(struct hv_device *device,
                   struct vmpacket_descriptor *packet)
{
    struct netvsc_device *net_device;
    struct nvsp_message *nvsp_packet;
    struct hv_netvsc_packet *nvsc_packet;
    struct net_device *ndev;

    net_device = get_inbound_net_device(device);
    if (!net_device)
        return;
    ndev = net_device->ndev;

    nvsp_packet = (struct nvsp_message *)((unsigned long)packet +
            (packet->offset8 << 3));

    if ((nvsp_packet->hdr.msg_type == NVSP_MSG_TYPE_INIT_COMPLETE) ||
        (nvsp_packet->hdr.msg_type ==
         NVSP_MSG1_TYPE_SEND_RECV_BUF_COMPLETE) ||
        (nvsp_packet->hdr.msg_type ==
         NVSP_MSG1_TYPE_SEND_SEND_BUF_COMPLETE)) {
        /* Copy the response back */
        memcpy(&net_device->channel_init_pkt, nvsp_packet,
               sizeof(struct nvsp_message));
        complete(&net_device->channel_init_wait);
    } else if (nvsp_packet->hdr.msg_type ==
           NVSP_MSG1_TYPE_SEND_RNDIS_PKT_COMPLETE) {
        int num_outstanding_sends;

        /* Get the send context */
        nvsc_packet = (struct hv_netvsc_packet *)(unsigned long)
            packet->trans_id;

        /* Notify the layer above us */
        nvsc_packet->completion.send.send_completion(
            nvsc_packet->completion.send.send_completion_ctx);

        num_outstanding_sends =
            atomic_dec_return(&net_device->num_outstanding_sends);

        if (net_device->destroy && num_outstanding_sends == 0)
            wake_up(&net_device->wait_drain);

        if (netif_queue_stopped(ndev) && !net_device->start_remove &&
            (hv_ringbuf_avail_percent(&device->channel->outbound)
            > RING_AVAIL_PERCENT_HIWATER ||
            num_outstanding_sends < 1))
                netif_wake_queue(ndev);
    } else {
        netdev_err(ndev, "Unknown send completion packet type- "
               "%d received!!\n", nvsp_packet->hdr.msg_type);
    }

}

int netvsc_send(struct hv_device *device,
            struct hv_netvsc_packet *packet)
{
    struct netvsc_device *net_device;
    int ret = 0;
    struct nvsp_message sendMessage;
    struct net_device *ndev;

    net_device = get_outbound_net_device(device);
    if (!net_device)
        return -ENODEV;
    ndev = net_device->ndev;

    sendMessage.hdr.msg_type = NVSP_MSG1_TYPE_SEND_RNDIS_PKT;
    if (packet->is_data_pkt) {
        /* 0 is RMC_DATA; */
        sendMessage.msg.v1_msg.send_rndis_pkt.channel_type = 0;
    } else {
        /* 1 is RMC_CONTROL; */
        sendMessage.msg.v1_msg.send_rndis_pkt.channel_type = 1;
    }

    /* Not using send buffer section */
    sendMessage.msg.v1_msg.send_rndis_pkt.send_buf_section_index =
        0xFFFFFFFF;
    sendMessage.msg.v1_msg.send_rndis_pkt.send_buf_section_size = 0;

    if (packet->page_buf_cnt) {
        ret = vmbus_sendpacket_pagebuffer(device->channel,
                          packet->page_buf,
                          packet->page_buf_cnt,
                          &sendMessage,
                          sizeof(struct nvsp_message),
                          (unsigned long)packet);
    } else {
        ret = vmbus_sendpacket(device->channel, &sendMessage,
                sizeof(struct nvsp_message),
                (unsigned long)packet,
                VM_PKT_DATA_INBAND,
                VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);

    }

    if (ret == 0) {
        atomic_inc(&net_device->num_outstanding_sends);
        if (hv_ringbuf_avail_percent(&device->channel->outbound) <
            RING_AVAIL_PERCENT_LOWATER) {
            netif_stop_queue(ndev);
            if (atomic_read(&net_device->
                num_outstanding_sends) < 1)
                netif_wake_queue(ndev);
        }
    } else if (ret == -EAGAIN) {
        netif_stop_queue(ndev);
        if (atomic_read(&net_device->num_outstanding_sends) < 1) {
            netif_wake_queue(ndev);
            ret = -ENOSPC;
        }
    } else {
        netdev_err(ndev, "Unable to send packet %p ret %d\n",
               packet, ret);
    }

    return ret;
}

static void netvsc_send_recv_completion(struct hv_device *device,
                    u64 transaction_id, u32 status)
{
    struct nvsp_message recvcompMessage;
    int retries = 0;
    int ret;
    struct net_device *ndev;
    struct netvsc_device *net_device = hv_get_drvdata(device);

    ndev = net_device->ndev;

    recvcompMessage.hdr.msg_type =
                NVSP_MSG1_TYPE_SEND_RNDIS_PKT_COMPLETE;

    recvcompMessage.msg.v1_msg.send_rndis_pkt_complete.status = status;

retry_send_cmplt:
    /* Send the completion */
    ret = vmbus_sendpacket(device->channel, &recvcompMessage,
                   sizeof(struct nvsp_message), transaction_id,
                   VM_PKT_COMP, 0);
    if (ret == 0) {
        /* success */
        /* no-op */
    } else if (ret == -EAGAIN) {
        /* no more room...wait a bit and attempt to retry 3 times */
        retries++;
        netdev_err(ndev, "unable to send receive completion pkt"
            " (tid %llx)...retrying %d\n", transaction_id, retries);

        if (retries < 4) {
            udelay(100);
            goto retry_send_cmplt;
        } else {
            netdev_err(ndev, "unable to send receive "
                "completion pkt (tid %llx)...give up retrying\n",
                transaction_id);
        }
    } else {
        netdev_err(ndev, "unable to send receive "
            "completion pkt - %llx\n", transaction_id);
    }
}

/* Send a receive completion packet to RNDIS device (ie NetVsp) */
static void netvsc_receive_completion(void *context)
{
    struct hv_netvsc_packet *packet = context;
    struct hv_device *device = packet->device;
    struct netvsc_device *net_device;
    u64 transaction_id = 0;
    bool fsend_receive_comp = false;
    unsigned long flags;
    struct net_device *ndev;
    u32 status = NVSP_STAT_NONE;

    /*
     * Even though it seems logical to do a GetOutboundNetDevice() here to
     * send out receive completion, we are using GetInboundNetDevice()
     * since we may have disable outbound traffic already.
     */
    net_device = get_inbound_net_device(device);
    if (!net_device)
        return;
    ndev = net_device->ndev;

    /* Overloading use of the lock. */
    spin_lock_irqsave(&net_device->recv_pkt_list_lock, flags);

    if (packet->status != NVSP_STAT_SUCCESS)
        packet->xfer_page_pkt->status = NVSP_STAT_FAIL;

    packet->xfer_page_pkt->count--;

    /*
     * Last one in the line that represent 1 xfer page packet.
     * Return the xfer page packet itself to the freelist
     */
    if (packet->xfer_page_pkt->count == 0) {
        fsend_receive_comp = true;
        transaction_id = packet->completion.recv.recv_completion_tid;
        status = packet->xfer_page_pkt->status;
        list_add_tail(&packet->xfer_page_pkt->list_ent,
                  &net_device->recv_pkt_list);

    }

    /* Put the packet back */
    list_add_tail(&packet->list_ent, &net_device->recv_pkt_list);
    spin_unlock_irqrestore(&net_device->recv_pkt_list_lock, flags);

    /* Send a receive completion for the xfer page packet */
    if (fsend_receive_comp)
        netvsc_send_recv_completion(device, transaction_id, status);

}

static void netvsc_receive(struct hv_device *device,
                struct vmpacket_descriptor *packet)
{
    struct netvsc_device *net_device;
    struct vmtransfer_page_packet_header *vmxferpage_packet;
    struct nvsp_message *nvsp_packet;
    struct hv_netvsc_packet *netvsc_packet = NULL;
    /* struct netvsc_driver *netvscDriver; */
    struct xferpage_packet *xferpage_packet = NULL;
    int i;
    int count = 0;
    unsigned long flags;
    struct net_device *ndev;

    LIST_HEAD(listHead);

    net_device = get_inbound_net_device(device);
    if (!net_device)
        return;
    ndev = net_device->ndev;

    /*
     * All inbound packets other than send completion should be xfer page
     * packet
     */
    if (packet->type != VM_PKT_DATA_USING_XFER_PAGES) {
        netdev_err(ndev, "Unknown packet type received - %d\n",
               packet->type);
        return;
    }

    nvsp_packet = (struct nvsp_message *)((unsigned long)packet +
            (packet->offset8 << 3));

    /* Make sure this is a valid nvsp packet */
    if (nvsp_packet->hdr.msg_type !=
        NVSP_MSG1_TYPE_SEND_RNDIS_PKT) {
        netdev_err(ndev, "Unknown nvsp packet type received-"
            " %d\n", nvsp_packet->hdr.msg_type);
        return;
    }

    vmxferpage_packet = (struct vmtransfer_page_packet_header *)packet;

    if (vmxferpage_packet->xfer_pageset_id != NETVSC_RECEIVE_BUFFER_ID) {
        netdev_err(ndev, "Invalid xfer page set id - "
               "expecting %x got %x\n", NETVSC_RECEIVE_BUFFER_ID,
               vmxferpage_packet->xfer_pageset_id);
        return;
    }

    /*
     * Grab free packets (range count + 1) to represent this xfer
     * page packet. +1 to represent the xfer page packet itself.
     * We grab it here so that we know exactly how many we can
     * fulfil
     */
    spin_lock_irqsave(&net_device->recv_pkt_list_lock, flags);
    while (!list_empty(&net_device->recv_pkt_list)) {
        list_move_tail(net_device->recv_pkt_list.next, &listHead);
        if (++count == vmxferpage_packet->range_cnt + 1)
            break;
    }
    spin_unlock_irqrestore(&net_device->recv_pkt_list_lock, flags);

    /*
     * We need at least 2 netvsc pkts (1 to represent the xfer
     * page and at least 1 for the range) i.e. we can handled
     * some of the xfer page packet ranges...
     */
    if (count < 2) {
        netdev_err(ndev, "Got only %d netvsc pkt...needed "
            "%d pkts. Dropping this xfer page packet completely!\n",
            count, vmxferpage_packet->range_cnt + 1);

        /* Return it to the freelist */
        spin_lock_irqsave(&net_device->recv_pkt_list_lock, flags);
        for (i = count; i != 0; i--) {
            list_move_tail(listHead.next,
                       &net_device->recv_pkt_list);
        }
        spin_unlock_irqrestore(&net_device->recv_pkt_list_lock,
                       flags);

        netvsc_send_recv_completion(device,
                        vmxferpage_packet->d.trans_id,
                        NVSP_STAT_FAIL);

        return;
    }

    /* Remove the 1st packet to represent the xfer page packet itself */
    xferpage_packet = (struct xferpage_packet *)listHead.next;
    list_del(&xferpage_packet->list_ent);
    xferpage_packet->status = NVSP_STAT_SUCCESS;

    /* This is how much we can satisfy */
    xferpage_packet->count = count - 1;

    if (xferpage_packet->count != vmxferpage_packet->range_cnt) {
        netdev_err(ndev, "Needed %d netvsc pkts to satisfy "
            "this xfer page...got %d\n",
            vmxferpage_packet->range_cnt, xferpage_packet->count);
    }

    /* Each range represents 1 RNDIS pkt that contains 1 ethernet frame */
    for (i = 0; i < (count - 1); i++) {
        netvsc_packet = (struct hv_netvsc_packet *)listHead.next;
        list_del(&netvsc_packet->list_ent);

        /* Initialize the netvsc packet */
        netvsc_packet->status = NVSP_STAT_SUCCESS;
        netvsc_packet->xfer_page_pkt = xferpage_packet;
        netvsc_packet->completion.recv.recv_completion =
                    netvsc_receive_completion;
        netvsc_packet->completion.recv.recv_completion_ctx =
                    netvsc_packet;
        netvsc_packet->device = device;
        /* Save this so that we can send it back */
        netvsc_packet->completion.recv.recv_completion_tid =
                    vmxferpage_packet->d.trans_id;

        netvsc_packet->data = (void *)((unsigned long)net_device->
            recv_buf + vmxferpage_packet->ranges[i].byte_offset);
        netvsc_packet->total_data_buflen =
                    vmxferpage_packet->ranges[i].byte_count;

        /* Pass it to the upper layer */
        rndis_filter_receive(device, netvsc_packet);

        netvsc_receive_completion(netvsc_packet->
                completion.recv.recv_completion_ctx);
    }

}

static void netvsc_channel_cb(void *context)
{
    int ret;
    struct hv_device *device = context;
    struct netvsc_device *net_device;
    u32 bytes_recvd;
    u64 request_id;
    unsigned char *packet;
    struct vmpacket_descriptor *desc;
    unsigned char *buffer;
    int bufferlen = NETVSC_PACKET_SIZE;
    struct net_device *ndev;

    packet = kzalloc(NETVSC_PACKET_SIZE * sizeof(unsigned char),
             GFP_ATOMIC);
    if (!packet)
        return;
    buffer = packet;

    net_device = get_inbound_net_device(device);
    if (!net_device)
        goto out;
    ndev = net_device->ndev;

    do {
        ret = vmbus_recvpacket_raw(device->channel, buffer, bufferlen,
                       &bytes_recvd, &request_id);
        if (ret == 0) {
            if (bytes_recvd > 0) {
                desc = (struct vmpacket_descriptor *)buffer;
                switch (desc->type) {
                case VM_PKT_COMP:
                    netvsc_send_completion(device, desc);
                    break;

                case VM_PKT_DATA_USING_XFER_PAGES:
                    netvsc_receive(device, desc);
                    break;

                default:
                    netdev_err(ndev,
                           "unhandled packet type %d, "
                           "tid %llx len %d\n",
                           desc->type, request_id,
                           bytes_recvd);
                    break;
                }

                /* reset */
                if (bufferlen > NETVSC_PACKET_SIZE) {
                    kfree(buffer);
                    buffer = packet;
                    bufferlen = NETVSC_PACKET_SIZE;
                }
            } else {
                /* reset */
                if (bufferlen > NETVSC_PACKET_SIZE) {
                    kfree(buffer);
                    buffer = packet;
                    bufferlen = NETVSC_PACKET_SIZE;
                }

                break;
            }
        } else if (ret == -ENOBUFS) {
            /* Handle large packet */
            buffer = kmalloc(bytes_recvd, GFP_ATOMIC);
            if (buffer == NULL) {
                /* Try again next time around */
                netdev_err(ndev,
                       "unable to allocate buffer of size "
                       "(%d)!!\n", bytes_recvd);
                break;
            }

            bufferlen = bytes_recvd;
        }
    } while (1);

out:
    kfree(buffer);
    return;
}

/*
 * netvsc_device_add - Callback when the device belonging to this
 * driver is added
 */
int netvsc_device_add(struct hv_device *device, void *additional_info)
{
    int ret = 0;
    int i;
    int ring_size =
    ((struct netvsc_device_info *)additional_info)->ring_size;
    struct netvsc_device *net_device;
    struct hv_netvsc_packet *packet, *pos;
    struct net_device *ndev;

    net_device = alloc_net_device(device);
    if (!net_device) {
        ret = -ENOMEM;
        goto cleanup;
    }

    /*
     * Coming into this function, struct net_device * is
     * registered as the driver private data.
     * In alloc_net_device(), we register struct netvsc_device *
     * as the driver private data and stash away struct net_device *
     * in struct netvsc_device *.
     */
    ndev = net_device->ndev;

    /* Initialize the NetVSC channel extension */
    net_device->recv_buf_size = NETVSC_RECEIVE_BUFFER_SIZE;
    spin_lock_init(&net_device->recv_pkt_list_lock);

    INIT_LIST_HEAD(&net_device->recv_pkt_list);

    for (i = 0; i < NETVSC_RECEIVE_PACKETLIST_COUNT; i++) {
        packet = kzalloc(sizeof(struct hv_netvsc_packet), GFP_KERNEL);
        if (!packet)
            break;

        list_add_tail(&packet->list_ent,
                  &net_device->recv_pkt_list);
    }
    init_completion(&net_device->channel_init_wait);

    /* Open the channel */
    ret = vmbus_open(device->channel, ring_size * PAGE_SIZE,
             ring_size * PAGE_SIZE, NULL, 0,
             netvsc_channel_cb, device);

    if (ret != 0) {
        netdev_err(ndev, "unable to open channel: %d\n", ret);
        goto cleanup;
    }

    /* Channel is opened */
    pr_info("hv_netvsc channel opened successfully\n");

    /* Connect with the NetVsp */
    ret = netvsc_connect_vsp(device);
    if (ret != 0) {
        netdev_err(ndev,
            "unable to connect to NetVSP - %d\n", ret);
        goto close;
    }

    return ret;

close:
    /* Now, we can close the channel safely */
    vmbus_close(device->channel);

cleanup:

    if (net_device) {
        list_for_each_entry_safe(packet, pos,
                     &net_device->recv_pkt_list,
                     list_ent) {
            list_del(&packet->list_ent);
            kfree(packet);
        }

        kfree(net_device);
    }

    return ret;
}