/*
 * 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 <haiyangz@microsoft.com>
 *   Hank Janssen  <hjanssen@microsoft.com>
 */
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/wait.h>
#include <linux/highmem.h>
#include <linux/slab.h>
#include <linux/io.h>
#include <linux/if_ether.h>
#include <linux/netdevice.h>

#include "hyperv_net.h"


enum rndis_device_state {
        RNDIS_DEV_UNINITIALIZED = 0,
        RNDIS_DEV_INITIALIZING,
        RNDIS_DEV_INITIALIZED,
        RNDIS_DEV_DATAINITIALIZED,
};

struct rndis_device {
        struct netvsc_device *net_dev;

        enum rndis_device_state state;
        bool link_state;
        atomic_t new_req_id;

        spinlock_t request_lock;
        struct list_head req_list;

        unsigned char hw_mac_adr[ETH_ALEN];
};

struct rndis_request {
        struct list_head list_ent;
        struct completion  wait_event;

        /*
         * FIXME: We assumed a fixed size response here. If we do ever need to
         * handle a bigger response, we can either define a max response
         * message or add a response buffer variable above this field
         */
        struct rndis_message response_msg;

        /* Simplify allocation by having a netvsc packet inline */
        struct hv_netvsc_packet pkt;
        struct hv_page_buffer buf;
        /* FIXME: We assumed a fixed size request here. */
        struct rndis_message request_msg;
};

static void rndis_filter_send_completion(void *ctx);

static void rndis_filter_send_request_completion(void *ctx);



static struct rndis_device *get_rndis_device(void)
{
        struct rndis_device *device;

        device = kzalloc(sizeof(struct rndis_device), GFP_KERNEL);
        if (!device)
                return NULL;

        spin_lock_init(&device->request_lock);

        INIT_LIST_HEAD(&device->req_list);

        device->state = RNDIS_DEV_UNINITIALIZED;

        return device;
}

static struct rndis_request *get_rndis_request(struct rndis_device *dev,
                                             u32 msg_type,
                                             u32 msg_len)
{
        struct rndis_request *request;
        struct rndis_message *rndis_msg;
        struct rndis_set_request *set;
        unsigned long flags;

        request = kzalloc(sizeof(struct rndis_request), GFP_KERNEL);
        if (!request)
                return NULL;

        init_completion(&request->wait_event);

        rndis_msg = &request->request_msg;
        rndis_msg->ndis_msg_type = msg_type;
        rndis_msg->msg_len = msg_len;

        /*
         * Set the request id. This field is always after the rndis header for
         * request/response packet types so we just used the SetRequest as a
         * template
         */
        set = &rndis_msg->msg.set_req;
        set->req_id = atomic_inc_return(&dev->new_req_id);

        /* Add to the request list */
        spin_lock_irqsave(&dev->request_lock, flags);
        list_add_tail(&request->list_ent, &dev->req_list);
        spin_unlock_irqrestore(&dev->request_lock, flags);

        return request;
}

static void put_rndis_request(struct rndis_device *dev,
                            struct rndis_request *req)
{
        unsigned long flags;

        spin_lock_irqsave(&dev->request_lock, flags);
        list_del(&req->list_ent);
        spin_unlock_irqrestore(&dev->request_lock, flags);

        kfree(req);
}

static void dump_rndis_message(struct hv_device *hv_dev,
                        struct rndis_message *rndis_msg)
{
        struct net_device *netdev;
        struct netvsc_device *net_device;

        net_device = hv_get_drvdata(hv_dev);
        netdev = net_device->ndev;

        switch (rndis_msg->ndis_msg_type) {
        case REMOTE_NDIS_PACKET_MSG:
                netdev_dbg(netdev, "REMOTE_NDIS_PACKET_MSG (len %u, "
                           "data offset %u data len %u, # oob %u, "
                           "oob offset %u, oob len %u, pkt offset %u, "
                           "pkt len %u\n",
                           rndis_msg->msg_len,
                           rndis_msg->msg.pkt.data_offset,
                           rndis_msg->msg.pkt.data_len,
                           rndis_msg->msg.pkt.num_oob_data_elements,
                           rndis_msg->msg.pkt.oob_data_offset,
                           rndis_msg->msg.pkt.oob_data_len,
                           rndis_msg->msg.pkt.per_pkt_info_offset,
                           rndis_msg->msg.pkt.per_pkt_info_len);
                break;

        case REMOTE_NDIS_INITIALIZE_CMPLT:
                netdev_dbg(netdev, "REMOTE_NDIS_INITIALIZE_CMPLT "
                        "(len %u, id 0x%x, status 0x%x, major %d, minor %d, "
                        "device flags %d, max xfer size 0x%x, max pkts %u, "
                        "pkt aligned %u)\n",
                        rndis_msg->msg_len,
                        rndis_msg->msg.init_complete.req_id,
                        rndis_msg->msg.init_complete.status,
                        rndis_msg->msg.init_complete.major_ver,
                        rndis_msg->msg.init_complete.minor_ver,
                        rndis_msg->msg.init_complete.dev_flags,
                        rndis_msg->msg.init_complete.max_xfer_size,
                        rndis_msg->msg.init_complete.
                           max_pkt_per_msg,
                        rndis_msg->msg.init_complete.
                           pkt_alignment_factor);
                break;

        case REMOTE_NDIS_QUERY_CMPLT:
                netdev_dbg(netdev, "REMOTE_NDIS_QUERY_CMPLT "
                        "(len %u, id 0x%x, status 0x%x, buf len %u, "
                        "buf offset %u)\n",
                        rndis_msg->msg_len,
                        rndis_msg->msg.query_complete.req_id,
                        rndis_msg->msg.query_complete.status,
                        rndis_msg->msg.query_complete.
                           info_buflen,
                        rndis_msg->msg.query_complete.
                           info_buf_offset);
                break;

        case REMOTE_NDIS_SET_CMPLT:
                netdev_dbg(netdev,
                        "REMOTE_NDIS_SET_CMPLT (len %u, id 0x%x, status 0x%x)\n",
                        rndis_msg->msg_len,
                        rndis_msg->msg.set_complete.req_id,
                        rndis_msg->msg.set_complete.status);
                break;

        case REMOTE_NDIS_INDICATE_STATUS_MSG:
                netdev_dbg(netdev, "REMOTE_NDIS_INDICATE_STATUS_MSG "
                        "(len %u, status 0x%x, buf len %u, buf offset %u)\n",
                        rndis_msg->msg_len,
                        rndis_msg->msg.indicate_status.status,
                        rndis_msg->msg.indicate_status.status_buflen,
                        rndis_msg->msg.indicate_status.status_buf_offset);
                break;

        default:
                netdev_dbg(netdev, "0x%x (len %u)\n",
                        rndis_msg->ndis_msg_type,
                        rndis_msg->msg_len);
                break;
        }
}

static int rndis_filter_send_request(struct rndis_device *dev,
                                  struct rndis_request *req)
{
        int ret;
        struct hv_netvsc_packet *packet;

        /* Setup the packet to send it */
        packet = &req->pkt;

        packet->is_data_pkt = false;
        packet->total_data_buflen = req->request_msg.msg_len;
        packet->page_buf_cnt = 1;

        packet->page_buf[0].pfn = virt_to_phys(&req->request_msg) >>
                                        PAGE_SHIFT;
        packet->page_buf[0].len = req->request_msg.msg_len;
        packet->page_buf[0].offset =
                (unsigned long)&req->request_msg & (PAGE_SIZE - 1);

        packet->completion.send.send_completion_ctx = req;/* packet; */
        packet->completion.send.send_completion =
                rndis_filter_send_request_completion;
        packet->completion.send.send_completion_tid = (unsigned long)dev;

        ret = netvsc_send(dev->net_dev->dev, packet);
        return ret;
}

static void rndis_filter_receive_response(struct rndis_device *dev,
                                       struct rndis_message *resp)
{
        struct rndis_request *request = NULL;
        bool found = false;
        unsigned long flags;
        struct net_device *ndev;

        ndev = dev->net_dev->ndev;

        spin_lock_irqsave(&dev->request_lock, flags);
        list_for_each_entry(request, &dev->req_list, list_ent) {
                /*
                 * All request/response message contains RequestId as the 1st
                 * field
                 */
                if (request->request_msg.msg.init_req.req_id
                    == resp->msg.init_complete.req_id) {
                        found = true;
                        break;
                }
        }
        spin_unlock_irqrestore(&dev->request_lock, flags);

        if (found) {
                if (resp->msg_len <= sizeof(struct rndis_message)) {
                        memcpy(&request->response_msg, resp,
                               resp->msg_len);
                } else {
                        netdev_err(ndev,
                                "rndis response buffer overflow "
                                "detected (size %u max %zu)\n",
                                resp->msg_len,
                                sizeof(struct rndis_filter_packet));

                        if (resp->ndis_msg_type ==
                            REMOTE_NDIS_RESET_CMPLT) {
                                /* does not have a request id field */
                                request->response_msg.msg.reset_complete.
                                        status = STATUS_BUFFER_OVERFLOW;
                        } else {
                                request->response_msg.msg.
                                init_complete.status =
                                        STATUS_BUFFER_OVERFLOW;
                        }
                }

                complete(&request->wait_event);
        } else {
                netdev_err(ndev,
                        "no rndis request found for this response "
                        "(id 0x%x res type 0x%x)\n",
                        resp->msg.init_complete.req_id,
                        resp->ndis_msg_type);
        }
}

static void rndis_filter_receive_indicate_status(struct rndis_device *dev,
                                             struct rndis_message *resp)
{
        struct rndis_indicate_status *indicate =
                        &resp->msg.indicate_status;

        if (indicate->status == RNDIS_STATUS_MEDIA_CONNECT) {
                netvsc_linkstatus_callback(
                        dev->net_dev->dev, 1);
        } else if (indicate->status == RNDIS_STATUS_MEDIA_DISCONNECT) {
                netvsc_linkstatus_callback(
                        dev->net_dev->dev, 0);
        } else {
                /*
                 * TODO:
                 */
        }
}

static void rndis_filter_receive_data(struct rndis_device *dev,
                                   struct rndis_message *msg,
                                   struct hv_netvsc_packet *pkt)
{
        struct rndis_packet *rndis_pkt;
        u32 data_offset;
        int i;

        rndis_pkt = &msg->msg.pkt;

        /*
         * FIXME: Handle multiple rndis pkt msgs that maybe enclosed in this
         * netvsc packet (ie TotalDataBufferLength != MessageLength)
         */

        /* Remove the rndis header and pass it back up the stack */
        data_offset = RNDIS_HEADER_SIZE + rndis_pkt->data_offset;

        pkt->total_data_buflen -= data_offset;
        pkt->page_buf[0].offset += data_offset;
        pkt->page_buf[0].len -= data_offset;

        /* Drop the 0th page, if rndis data go beyond page boundary */
        if (pkt->page_buf[0].offset >= PAGE_SIZE) {
                pkt->page_buf[1].offset = pkt->page_buf[0].offset - PAGE_SIZE;
                pkt->page_buf[1].len -= pkt->page_buf[1].offset;
                pkt->page_buf_cnt--;
                for (i = 0; i < pkt->page_buf_cnt; i++)
                        pkt->page_buf[i] = pkt->page_buf[i+1];
        }

        pkt->is_data_pkt = true;

        netvsc_recv_callback(dev->net_dev->dev, pkt);
}

int rndis_filter_receive(struct hv_device *dev,
                                struct hv_netvsc_packet *pkt)
{
        struct netvsc_device *net_dev = hv_get_drvdata(dev);
        struct rndis_device *rndis_dev;
        struct rndis_message rndis_msg;
        struct rndis_message *rndis_hdr;
        struct net_device *ndev;

        if (!net_dev)
                return -EINVAL;

        ndev = net_dev->ndev;

        /* Make sure the rndis device state is initialized */
        if (!net_dev->extension) {
                netdev_err(ndev, "got rndis message but no rndis device - "
                          "dropping this message!\n");
                return -ENODEV;
        }

        rndis_dev = (struct rndis_device *)net_dev->extension;
        if (rndis_dev->state == RNDIS_DEV_UNINITIALIZED) {
                netdev_err(ndev, "got rndis message but rndis device "
                           "uninitialized...dropping this message!\n");
                return -ENODEV;
        }

        rndis_hdr = (struct rndis_message *)kmap_atomic(
                        pfn_to_page(pkt->page_buf[0].pfn), KM_IRQ0);

        rndis_hdr = (void *)((unsigned long)rndis_hdr +
                        pkt->page_buf[0].offset);

        /* Make sure we got a valid rndis message */
        if ((rndis_hdr->ndis_msg_type != REMOTE_NDIS_PACKET_MSG) &&
            (rndis_hdr->msg_len > sizeof(struct rndis_message))) {
                netdev_err(ndev, "incoming rndis message buffer overflow "
                           "detected (got %u, max %zu)..marking it an error!\n",
                           rndis_hdr->msg_len,
                           sizeof(struct rndis_message));
        }

        memcpy(&rndis_msg, rndis_hdr,
                (rndis_hdr->msg_len > sizeof(struct rndis_message)) ?
                        sizeof(struct rndis_message) :
                        rndis_hdr->msg_len);

        kunmap_atomic(rndis_hdr - pkt->page_buf[0].offset, KM_IRQ0);

        dump_rndis_message(dev, &rndis_msg);

        switch (rndis_msg.ndis_msg_type) {
        case REMOTE_NDIS_PACKET_MSG:
                /* data msg */
                rndis_filter_receive_data(rndis_dev, &rndis_msg, pkt);
                break;

        case REMOTE_NDIS_INITIALIZE_CMPLT:
        case REMOTE_NDIS_QUERY_CMPLT:
        case REMOTE_NDIS_SET_CMPLT:
                /* completion msgs */
                rndis_filter_receive_response(rndis_dev, &rndis_msg);
                break;

        case REMOTE_NDIS_INDICATE_STATUS_MSG:
                /* notification msgs */
                rndis_filter_receive_indicate_status(rndis_dev, &rndis_msg);
                break;
        default:
                netdev_err(ndev,
                        "unhandled rndis message (type %u len %u)\n",
                           rndis_msg.ndis_msg_type,
                           rndis_msg.msg_len);
                break;
        }

        return 0;
}

static int rndis_filter_query_device(struct rndis_device *dev, u32 oid,
                                  void *result, u32 *result_size)
{
        struct rndis_request *request;
        u32 inresult_size = *result_size;
        struct rndis_query_request *query;
        struct rndis_query_complete *query_complete;
        int ret = 0;
        int t;

        if (!result)
                return -EINVAL;

        *result_size = 0;
        request = get_rndis_request(dev, REMOTE_NDIS_QUERY_MSG,
                        RNDIS_MESSAGE_SIZE(struct rndis_query_request));
        if (!request) {
                ret = -ENOMEM;
                goto cleanup;
        }

        /* Setup the rndis query */
        query = &request->request_msg.msg.query_req;
        query->oid = oid;
        query->info_buf_offset = sizeof(struct rndis_query_request);
        query->info_buflen = 0;
        query->dev_vc_handle = 0;

        ret = rndis_filter_send_request(dev, request);
        if (ret != 0)
                goto cleanup;

        t = wait_for_completion_timeout(&request->wait_event, 5*HZ);
        if (t == 0) {
                ret = -ETIMEDOUT;
                goto cleanup;
        }

        /* Copy the response back */
        query_complete = &request->response_msg.msg.query_complete;

        if (query_complete->info_buflen > inresult_size) {
                ret = -1;
                goto cleanup;
        }

        memcpy(result,
               (void *)((unsigned long)query_complete +
                         query_complete->info_buf_offset),
               query_complete->info_buflen);

        *result_size = query_complete->info_buflen;

cleanup:
        if (request)
                put_rndis_request(dev, request);

        return ret;
}

static int rndis_filter_query_device_mac(struct rndis_device *dev)
{
        u32 size = ETH_ALEN;

        return rndis_filter_query_device(dev,
                                      RNDIS_OID_802_3_PERMANENT_ADDRESS,
                                      dev->hw_mac_adr, &size);
}

static int rndis_filter_query_device_link_status(struct rndis_device *dev)
{
        u32 size = sizeof(u32);
        u32 link_status;
        int ret;

        ret = rndis_filter_query_device(dev,
                                      RNDIS_OID_GEN_MEDIA_CONNECT_STATUS,
                                      &link_status, &size);
        dev->link_state = (link_status != 0) ? true : false;

        return ret;
}

static int rndis_filter_set_packet_filter(struct rndis_device *dev,
                                      u32 new_filter)
{
        struct rndis_request *request;
        struct rndis_set_request *set;
        struct rndis_set_complete *set_complete;
        u32 status;
        int ret, t;
        struct net_device *ndev;

        ndev = dev->net_dev->ndev;

        request = get_rndis_request(dev, REMOTE_NDIS_SET_MSG,
                        RNDIS_MESSAGE_SIZE(struct rndis_set_request) +
                        sizeof(u32));
        if (!request) {
                ret = -ENOMEM;
                goto cleanup;
        }

        /* Setup the rndis set */
        set = &request->request_msg.msg.set_req;
        set->oid = RNDIS_OID_GEN_CURRENT_PACKET_FILTER;
        set->info_buflen = sizeof(u32);
        set->info_buf_offset = sizeof(struct rndis_set_request);

        memcpy((void *)(unsigned long)set + sizeof(struct rndis_set_request),
               &new_filter, sizeof(u32));

        ret = rndis_filter_send_request(dev, request);
        if (ret != 0)
                goto cleanup;

        t = wait_for_completion_timeout(&request->wait_event, 5*HZ);

        if (t == 0) {
                netdev_err(ndev,
                        "timeout before we got a set response...\n");
                /*
                 * We can't deallocate the request since we may still receive a
                 * send completion for it.
                 */
                goto exit;
        } else {
                set_complete = &request->response_msg.msg.set_complete;
                status = set_complete->status;
        }

cleanup:
        if (request)
                put_rndis_request(dev, request);
exit:
        return ret;
}


static int rndis_filter_init_device(struct rndis_device *dev)
{
        struct rndis_request *request;
        struct rndis_initialize_request *init;
        struct rndis_initialize_complete *init_complete;
        u32 status;
        int ret, t;

        request = get_rndis_request(dev, REMOTE_NDIS_INITIALIZE_MSG,
                        RNDIS_MESSAGE_SIZE(struct rndis_initialize_request));
        if (!request) {
                ret = -ENOMEM;
                goto cleanup;
        }

        /* Setup the rndis set */
        init = &request->request_msg.msg.init_req;
        init->major_ver = RNDIS_MAJOR_VERSION;
        init->minor_ver = RNDIS_MINOR_VERSION;
        /* FIXME: Use 1536 - rounded ethernet frame size */
        init->max_xfer_size = 2048;

        dev->state = RNDIS_DEV_INITIALIZING;

        ret = rndis_filter_send_request(dev, request);
        if (ret != 0) {
                dev->state = RNDIS_DEV_UNINITIALIZED;
                goto cleanup;
        }


        t = wait_for_completion_timeout(&request->wait_event, 5*HZ);

        if (t == 0) {
                ret = -ETIMEDOUT;
                goto cleanup;
        }

        init_complete = &request->response_msg.msg.init_complete;
        status = init_complete->status;
        if (status == RNDIS_STATUS_SUCCESS) {
                dev->state = RNDIS_DEV_INITIALIZED;
                ret = 0;
        } else {
                dev->state = RNDIS_DEV_UNINITIALIZED;
                ret = -EINVAL;
        }

cleanup:
        if (request)
                put_rndis_request(dev, request);

        return ret;
}

static void rndis_filter_halt_device(struct rndis_device *dev)
{
        struct rndis_request *request;
        struct rndis_halt_request *halt;

        /* Attempt to do a rndis device halt */
        request = get_rndis_request(dev, REMOTE_NDIS_HALT_MSG,
                                RNDIS_MESSAGE_SIZE(struct rndis_halt_request));
        if (!request)
                goto cleanup;

        /* Setup the rndis set */
        halt = &request->request_msg.msg.halt_req;
        halt->req_id = atomic_inc_return(&dev->new_req_id);

        /* Ignore return since this msg is optional. */
        rndis_filter_send_request(dev, request);

        dev->state = RNDIS_DEV_UNINITIALIZED;

cleanup:
        if (request)
                put_rndis_request(dev, request);
        return;
}

static int rndis_filter_open_device(struct rndis_device *dev)
{
        int ret;

        if (dev->state != RNDIS_DEV_INITIALIZED)
                return 0;

        ret = rndis_filter_set_packet_filter(dev,
                                         NDIS_PACKET_TYPE_BROADCAST |
                                         NDIS_PACKET_TYPE_ALL_MULTICAST |
                                         NDIS_PACKET_TYPE_DIRECTED);
        if (ret == 0)
                dev->state = RNDIS_DEV_DATAINITIALIZED;

        return ret;
}

static int rndis_filter_close_device(struct rndis_device *dev)
{
        int ret;

        if (dev->state != RNDIS_DEV_DATAINITIALIZED)
                return 0;

        ret = rndis_filter_set_packet_filter(dev, 0);
        if (ret == 0)
                dev->state = RNDIS_DEV_INITIALIZED;

        return ret;
}

int rndis_filter_device_add(struct hv_device *dev,
                                  void *additional_info)
{
        int ret;
        struct netvsc_device *net_device;
        struct rndis_device *rndis_device;
        struct netvsc_device_info *device_info = additional_info;

        rndis_device = get_rndis_device();
        if (!rndis_device)
                return -ENODEV;

        /*
         * Let the inner driver handle this first to create the netvsc channel
         * NOTE! Once the channel is created, we may get a receive callback
         * (RndisFilterOnReceive()) before this call is completed
         */
        ret = netvsc_device_add(dev, additional_info);
        if (ret != 0) {
                kfree(rndis_device);
                return ret;
        }


        /* Initialize the rndis device */
        net_device = hv_get_drvdata(dev);

        net_device->extension = rndis_device;
        rndis_device->net_dev = net_device;

        /* Send the rndis initialization message */
        ret = rndis_filter_init_device(rndis_device);
        if (ret != 0) {
                /*
                 * TODO: If rndis init failed, we will need to shut down the
                 * channel
                 */
        }

        /* Get the mac address */
        ret = rndis_filter_query_device_mac(rndis_device);
        if (ret != 0) {
                /*
                 * TODO: shutdown rndis device and the channel
                 */
        }

        memcpy(device_info->mac_adr, rndis_device->hw_mac_adr, ETH_ALEN);

        rndis_filter_query_device_link_status(rndis_device);

        device_info->link_state = rndis_device->link_state;

        dev_info(&dev->device, "Device MAC %pM link state %s\n",
                 rndis_device->hw_mac_adr,
                 device_info->link_state ? "down" : "up");

        return ret;
}

void rndis_filter_device_remove(struct hv_device *dev)
{
        struct netvsc_device *net_dev = hv_get_drvdata(dev);
        struct rndis_device *rndis_dev = net_dev->extension;

        /* Halt and release the rndis device */
        rndis_filter_halt_device(rndis_dev);

        kfree(rndis_dev);
        net_dev->extension = NULL;

        netvsc_device_remove(dev);
}


int rndis_filter_open(struct hv_device *dev)
{
        struct netvsc_device *net_device = hv_get_drvdata(dev);

        if (!net_device)
                return -EINVAL;

        return rndis_filter_open_device(net_device->extension);
}

int rndis_filter_close(struct hv_device *dev)
{
        struct netvsc_device *netDevice = hv_get_drvdata(dev);

        if (!netDevice)
                return -EINVAL;

        return rndis_filter_close_device(netDevice->extension);
}

int rndis_filter_send(struct hv_device *dev,
                             struct hv_netvsc_packet *pkt)
{
        int ret;
        struct rndis_filter_packet *filterPacket;
        struct rndis_message *rndisMessage;
        struct rndis_packet *rndisPacket;
        u32 rndisMessageSize;

        /* Add the rndis header */
        filterPacket = (struct rndis_filter_packet *)pkt->extension;

        memset(filterPacket, 0, sizeof(struct rndis_filter_packet));

        rndisMessage = &filterPacket->msg;
        rndisMessageSize = RNDIS_MESSAGE_SIZE(struct rndis_packet);

        rndisMessage->ndis_msg_type = REMOTE_NDIS_PACKET_MSG;
        rndisMessage->msg_len = pkt->total_data_buflen +
                                      rndisMessageSize;

        rndisPacket = &rndisMessage->msg.pkt;
        rndisPacket->data_offset = sizeof(struct rndis_packet);
        rndisPacket->data_len = pkt->total_data_buflen;

        pkt->is_data_pkt = true;
        pkt->page_buf[0].pfn = virt_to_phys(rndisMessage) >> PAGE_SHIFT;
        pkt->page_buf[0].offset =
                        (unsigned long)rndisMessage & (PAGE_SIZE-1);
        pkt->page_buf[0].len = rndisMessageSize;

        /* Save the packet send completion and context */
        filterPacket->completion = pkt->completion.send.send_completion;
        filterPacket->completion_ctx =
                                pkt->completion.send.send_completion_ctx;

        /* Use ours */
        pkt->completion.send.send_completion = rndis_filter_send_completion;
        pkt->completion.send.send_completion_ctx = filterPacket;

        ret = netvsc_send(dev, pkt);
        if (ret != 0) {
                /*
                 * Reset the completion to originals to allow retries from
                 * above
                 */
                pkt->completion.send.send_completion =
                                filterPacket->completion;
                pkt->completion.send.send_completion_ctx =
                                filterPacket->completion_ctx;
        }

        return ret;
}

static void rndis_filter_send_completion(void *ctx)
{
        struct rndis_filter_packet *filterPacket = ctx;

        /* Pass it back to the original handler */
        filterPacket->completion(filterPacket->completion_ctx);
}


static void rndis_filter_send_request_completion(void *ctx)
{
        /* Noop */
}