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32 results

netvsc.c

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  • netvsc.c 39.21 KiB
    /*
     * 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, see <http://www.gnu.org/licenses/>.
     *
     * Authors:
     *   Haiyang Zhang <haiyangz@microsoft.com>
     *   Hank Janssen  <hjanssen@microsoft.com>
     */
    #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 <linux/vmalloc.h>
    #include <linux/rtnetlink.h>
    #include <linux/prefetch.h>
    
    #include <asm/sync_bitops.h>
    
    #include "hyperv_net.h"
    #include "netvsc_trace.h"
    
    /*
     * Switch the data path from the synthetic interface to the VF
     * interface.
     */
    void netvsc_switch_datapath(struct net_device *ndev, bool vf)
    {
    	struct net_device_context *net_device_ctx = netdev_priv(ndev);
    	struct hv_device *dev = net_device_ctx->device_ctx;
    	struct netvsc_device *nv_dev = rtnl_dereference(net_device_ctx->nvdev);
    	struct nvsp_message *init_pkt = &nv_dev->channel_init_pkt;
    
    	memset(init_pkt, 0, sizeof(struct nvsp_message));
    	init_pkt->hdr.msg_type = NVSP_MSG4_TYPE_SWITCH_DATA_PATH;
    	if (vf)
    		init_pkt->msg.v4_msg.active_dp.active_datapath =
    			NVSP_DATAPATH_VF;
    	else
    		init_pkt->msg.v4_msg.active_dp.active_datapath =
    			NVSP_DATAPATH_SYNTHETIC;
    
    	trace_nvsp_send(ndev, init_pkt);
    
    	vmbus_sendpacket(dev->channel, init_pkt,
    			       sizeof(struct nvsp_message),
    			       (unsigned long)init_pkt,
    			       VM_PKT_DATA_INBAND, 0);
    }
    
    /* Worker to setup sub channels on initial setup
     * Initial hotplug event occurs in softirq context
     * and can't wait for channels.
     */
    static void netvsc_subchan_work(struct work_struct *w)
    {
    	struct netvsc_device *nvdev =
    		container_of(w, struct netvsc_device, subchan_work);
    	struct rndis_device *rdev;
    	int i, ret;
    
    	/* Avoid deadlock with device removal already under RTNL */
    	if (!rtnl_trylock()) {
    		schedule_work(w);
    		return;
    	}
    
    	rdev = nvdev->extension;
    	if (rdev) {
    		ret = rndis_set_subchannel(rdev->ndev, nvdev);
    		if (ret == 0) {
    			netif_device_attach(rdev->ndev);
    		} else {
    			/* fallback to only primary channel */
    			for (i = 1; i < nvdev->num_chn; i++)
    				netif_napi_del(&nvdev->chan_table[i].napi);
    
    			nvdev->max_chn = 1;
    			nvdev->num_chn = 1;
    		}
    	}
    
    	rtnl_unlock();
    }
    
    static struct netvsc_device *alloc_net_device(void)
    {
    	struct netvsc_device *net_device;
    
    	net_device = kzalloc(sizeof(struct netvsc_device), GFP_KERNEL);
    	if (!net_device)
    		return NULL;
    
    	init_waitqueue_head(&net_device->wait_drain);
    	net_device->destroy = false;
    
    	net_device->max_pkt = RNDIS_MAX_PKT_DEFAULT;
    	net_device->pkt_align = RNDIS_PKT_ALIGN_DEFAULT;
    
    	init_completion(&net_device->channel_init_wait);
    	init_waitqueue_head(&net_device->subchan_open);
    	INIT_WORK(&net_device->subchan_work, netvsc_subchan_work);
    
    	return net_device;
    }
    
    static void free_netvsc_device(struct rcu_head *head)
    {
    	struct netvsc_device *nvdev
    		= container_of(head, struct netvsc_device, rcu);
    	int i;
    
    	kfree(nvdev->extension);
    	vfree(nvdev->recv_buf);
    	vfree(nvdev->send_buf);
    	kfree(nvdev->send_section_map);
    
    	for (i = 0; i < VRSS_CHANNEL_MAX; i++)
    		vfree(nvdev->chan_table[i].mrc.slots);
    
    	kfree(nvdev);
    }
    
    static void free_netvsc_device_rcu(struct netvsc_device *nvdev)
    {
    	call_rcu(&nvdev->rcu, free_netvsc_device);
    }
    
    static void netvsc_revoke_recv_buf(struct hv_device *device,
    				   struct netvsc_device *net_device,
    				   struct net_device *ndev)
    {
    	struct nvsp_message *revoke_packet;
    	int ret;
    
    	/*
    	 * 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;
    
    		trace_nvsp_send(ndev, revoke_packet);
    
    		ret = vmbus_sendpacket(device->channel,
    				       revoke_packet,
    				       sizeof(struct nvsp_message),
    				       (unsigned long)revoke_packet,
    				       VM_PKT_DATA_INBAND, 0);
    		/* If the failure is because the channel is rescinded;
    		 * ignore the failure since we cannot send on a rescinded
    		 * channel. This would allow us to properly cleanup
    		 * even when the channel is rescinded.
    		 */
    		if (device->channel->rescind)
    			ret = 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;
    		}
    		net_device->recv_section_cnt = 0;
    	}
    }
    
    static void netvsc_revoke_send_buf(struct hv_device *device,
    				   struct netvsc_device *net_device,
    				   struct net_device *ndev)
    {
    	struct nvsp_message *revoke_packet;
    	int ret;
    
    	/* Deal with the send buffer we may have setup.
    	 * If we got a  send section size, it means we received a
    	 * NVSP_MSG1_TYPE_SEND_SEND_BUF_COMPLETE msg (ie sent
    	 * NVSP_MSG1_TYPE_SEND_SEND_BUF msg) therefore, we need
    	 * to send a revoke msg here
    	 */
    	if (net_device->send_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_SEND_BUF;
    		revoke_packet->msg.v1_msg.revoke_send_buf.id =
    			NETVSC_SEND_BUFFER_ID;
    
    		trace_nvsp_send(ndev, revoke_packet);
    
    		ret = vmbus_sendpacket(device->channel,
    				       revoke_packet,
    				       sizeof(struct nvsp_message),
    				       (unsigned long)revoke_packet,
    				       VM_PKT_DATA_INBAND, 0);
    
    		/* If the failure is because the channel is rescinded;
    		 * ignore the failure since we cannot send on a rescinded
    		 * channel. This would allow us to properly cleanup
    		 * even when the channel is rescinded.
    		 */
    		if (device->channel->rescind)
    			ret = 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 send buffer to netvsp\n");
    			return;
    		}
    		net_device->send_section_cnt = 0;
    	}
    }
    
    static void netvsc_teardown_recv_gpadl(struct hv_device *device,
    				       struct netvsc_device *net_device,
    				       struct net_device *ndev)
    {
    	int ret;
    
    	if (net_device->recv_buf_gpadl_handle) {
    		ret = vmbus_teardown_gpadl(device->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;
    		}
    		net_device->recv_buf_gpadl_handle = 0;
    	}
    }
    
    static void netvsc_teardown_send_gpadl(struct hv_device *device,
    				       struct netvsc_device *net_device,
    				       struct net_device *ndev)
    {
    	int ret;
    
    	if (net_device->send_buf_gpadl_handle) {
    		ret = vmbus_teardown_gpadl(device->channel,
    					   net_device->send_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 send buffer's gpadl\n");
    			return;
    		}
    		net_device->send_buf_gpadl_handle = 0;
    	}
    }
    
    int netvsc_alloc_recv_comp_ring(struct netvsc_device *net_device, u32 q_idx)
    {
    	struct netvsc_channel *nvchan = &net_device->chan_table[q_idx];
    	int node = cpu_to_node(nvchan->channel->target_cpu);
    	size_t size;
    
    	size = net_device->recv_completion_cnt * sizeof(struct recv_comp_data);
    	nvchan->mrc.slots = vzalloc_node(size, node);
    	if (!nvchan->mrc.slots)
    		nvchan->mrc.slots = vzalloc(size);
    
    	return nvchan->mrc.slots ? 0 : -ENOMEM;
    }
    
    static int netvsc_init_buf(struct hv_device *device,
    			   struct netvsc_device *net_device,
    			   const struct netvsc_device_info *device_info)
    {
    	struct nvsp_1_message_send_receive_buffer_complete *resp;
    	struct net_device *ndev = hv_get_drvdata(device);
    	struct nvsp_message *init_packet;
    	unsigned int buf_size;
    	size_t map_words;
    	int ret = 0;
    
    	/* Get receive buffer area. */
    	buf_size = device_info->recv_sections * device_info->recv_section_size;
    	buf_size = roundup(buf_size, PAGE_SIZE);
    
    	/* Legacy hosts only allow smaller receive buffer */
    	if (net_device->nvsp_version <= NVSP_PROTOCOL_VERSION_2)
    		buf_size = min_t(unsigned int, buf_size,
    				 NETVSC_RECEIVE_BUFFER_SIZE_LEGACY);
    
    	net_device->recv_buf = vzalloc(buf_size);
    	if (!net_device->recv_buf) {
    		netdev_err(ndev,
    			   "unable to allocate receive buffer of size %u\n",
    			   buf_size);
    		ret = -ENOMEM;
    		goto cleanup;
    	}
    
    	net_device->recv_buf_size = buf_size;
    
    	/*
    	 * 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,
    				    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;
    
    	trace_nvsp_send(ndev, init_packet);
    
    	/* 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;
    	}
    
    	wait_for_completion(&net_device->channel_init_wait);
    
    	/* Check the response */
    	resp = &init_packet->msg.v1_msg.send_recv_buf_complete;
    	if (resp->status != NVSP_STAT_SUCCESS) {
    		netdev_err(ndev,
    			   "Unable to complete receive buffer initialization with NetVsp - status %d\n",
    			   resp->status);
    		ret = -EINVAL;
    		goto cleanup;
    	}
    
    	/* Parse the response */
    	netdev_dbg(ndev, "Receive sections: %u sub_allocs: size %u count: %u\n",
    		   resp->num_sections, resp->sections[0].sub_alloc_size,
    		   resp->sections[0].num_sub_allocs);
    
    	/* There should only be one section for the entire receive buffer */
    	if (resp->num_sections != 1 || resp->sections[0].offset != 0) {
    		ret = -EINVAL;
    		goto cleanup;
    	}
    
    	net_device->recv_section_size = resp->sections[0].sub_alloc_size;
    	net_device->recv_section_cnt = resp->sections[0].num_sub_allocs;
    
    	/* Setup receive completion ring */
    	net_device->recv_completion_cnt
    		= round_up(net_device->recv_section_cnt + 1,
    			   PAGE_SIZE / sizeof(u64));
    	ret = netvsc_alloc_recv_comp_ring(net_device, 0);
    	if (ret)
    		goto cleanup;
    
    	/* Now setup the send buffer. */
    	buf_size = device_info->send_sections * device_info->send_section_size;
    	buf_size = round_up(buf_size, PAGE_SIZE);
    
    	net_device->send_buf = vzalloc(buf_size);
    	if (!net_device->send_buf) {
    		netdev_err(ndev, "unable to allocate send buffer of size %u\n",
    			   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->send_buf,
    				    buf_size,
    				    &net_device->send_buf_gpadl_handle);
    	if (ret != 0) {
    		netdev_err(ndev,
    			   "unable to establish send 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_SEND_BUF;
    	init_packet->msg.v1_msg.send_send_buf.gpadl_handle =
    		net_device->send_buf_gpadl_handle;
    	init_packet->msg.v1_msg.send_send_buf.id = NETVSC_SEND_BUFFER_ID;
    
    	trace_nvsp_send(ndev, init_packet);
    
    	/* 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 send buffer's gpadl to netvsp\n");
    		goto cleanup;
    	}
    
    	wait_for_completion(&net_device->channel_init_wait);
    
    	/* Check the response */
    	if (init_packet->msg.v1_msg.
    	    send_send_buf_complete.status != NVSP_STAT_SUCCESS) {
    		netdev_err(ndev, "Unable to complete send buffer "
    			   "initialization with NetVsp - status %d\n",
    			   init_packet->msg.v1_msg.
    			   send_send_buf_complete.status);
    		ret = -EINVAL;
    		goto cleanup;
    	}
    
    	/* Parse the response */
    	net_device->send_section_size = init_packet->msg.
    				v1_msg.send_send_buf_complete.section_size;
    
    	/* Section count is simply the size divided by the section size. */
    	net_device->send_section_cnt = buf_size / net_device->send_section_size;
    
    	netdev_dbg(ndev, "Send section size: %d, Section count:%d\n",
    		   net_device->send_section_size, net_device->send_section_cnt);
    
    	/* Setup state for managing the send buffer. */
    	map_words = DIV_ROUND_UP(net_device->send_section_cnt, BITS_PER_LONG);
    
    	net_device->send_section_map = kcalloc(map_words, sizeof(ulong), GFP_KERNEL);
    	if (net_device->send_section_map == NULL) {
    		ret = -ENOMEM;
    		goto cleanup;
    	}
    
    	goto exit;
    
    cleanup:
    	netvsc_revoke_recv_buf(device, net_device, ndev);
    	netvsc_revoke_send_buf(device, net_device, ndev);
    	netvsc_teardown_recv_gpadl(device, net_device, ndev);
    	netvsc_teardown_send_gpadl(device, net_device, ndev);
    
    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)
    {
    	struct net_device *ndev = hv_get_drvdata(device);
    	int ret;
    
    	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;
    	trace_nvsp_send(ndev, init_packet);
    
    	/* 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;
    
    	wait_for_completion(&net_device->channel_init_wait);
    
    	if (init_packet->msg.init_msg.init_complete.status !=
    	    NVSP_STAT_SUCCESS)
    		return -EINVAL;
    
    	if (nvsp_ver == NVSP_PROTOCOL_VERSION_1)
    		return 0;
    
    	/* NVSPv2 or later: 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 = ndev->mtu + ETH_HLEN;
    	init_packet->msg.v2_msg.send_ndis_config.capability.ieee8021q = 1;
    
    	if (nvsp_ver >= NVSP_PROTOCOL_VERSION_5) {
    		init_packet->msg.v2_msg.send_ndis_config.capability.sriov = 1;
    
    		/* Teaming bit is needed to receive link speed updates */
    		init_packet->msg.v2_msg.send_ndis_config.capability.teaming = 1;
    	}
    
    	trace_nvsp_send(ndev, init_packet);
    
    	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,
    			      struct netvsc_device *net_device,
    			      const struct netvsc_device_info *device_info)
    {
    	struct net_device *ndev = hv_get_drvdata(device);
    	static const u32 ver_list[] = {
    		NVSP_PROTOCOL_VERSION_1, NVSP_PROTOCOL_VERSION_2,
    		NVSP_PROTOCOL_VERSION_4, NVSP_PROTOCOL_VERSION_5,
    		NVSP_PROTOCOL_VERSION_6, NVSP_PROTOCOL_VERSION_61
    	};
    	struct nvsp_message *init_packet;
    	int ndis_version, i, ret;
    
    	init_packet = &net_device->channel_init_pkt;
    
    	/* Negotiate the latest NVSP protocol supported */
    	for (i = ARRAY_SIZE(ver_list) - 1; i >= 0; i--)
    		if (negotiate_nvsp_ver(device, net_device, init_packet,
    				       ver_list[i])  == 0) {
    			net_device->nvsp_version = ver_list[i];
    			break;
    		}
    
    	if (i < 0) {
    		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));
    
    	if (net_device->nvsp_version <= NVSP_PROTOCOL_VERSION_4)
    		ndis_version = 0x00060001;
    	else
    		ndis_version = 0x0006001e;
    
    	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;
    
    	trace_nvsp_send(ndev, init_packet);
    
    	/* 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;
    
    
    	ret = netvsc_init_buf(device, net_device, device_info);
    
    cleanup:
    	return ret;
    }
    
    /*
     * netvsc_device_remove - Callback when the root bus device is removed
     */
    void netvsc_device_remove(struct hv_device *device)
    {
    	struct net_device *ndev = hv_get_drvdata(device);
    	struct net_device_context *net_device_ctx = netdev_priv(ndev);
    	struct netvsc_device *net_device
    		= rtnl_dereference(net_device_ctx->nvdev);
    	int i;
    
    	/*
    	 * Revoke receive buffer. If host is pre-Win2016 then tear down
    	 * receive buffer GPADL. Do the same for send buffer.
    	 */
    	netvsc_revoke_recv_buf(device, net_device, ndev);
    	if (vmbus_proto_version < VERSION_WIN10)
    		netvsc_teardown_recv_gpadl(device, net_device, ndev);
    
    	netvsc_revoke_send_buf(device, net_device, ndev);
    	if (vmbus_proto_version < VERSION_WIN10)
    		netvsc_teardown_send_gpadl(device, net_device, ndev);
    
    	RCU_INIT_POINTER(net_device_ctx->nvdev, NULL);
    
    	/* And disassociate NAPI context from device */
    	for (i = 0; i < net_device->num_chn; i++)
    		netif_napi_del(&net_device->chan_table[i].napi);
    
    	/*
    	 * At this point, no one should be accessing net_device
    	 * except in here
    	 */
    	netdev_dbg(ndev, "net device safe to remove\n");
    
    	/* Now, we can close the channel safely */
    	vmbus_close(device->channel);
    
    	/*
    	 * If host is Win2016 or higher then we do the GPADL tear down
    	 * here after VMBus is closed.
    	*/
    	if (vmbus_proto_version >= VERSION_WIN10) {
    		netvsc_teardown_recv_gpadl(device, net_device, ndev);
    		netvsc_teardown_send_gpadl(device, net_device, ndev);
    	}
    
    	/* Release all resources */
    	free_netvsc_device_rcu(net_device);
    }
    
    #define RING_AVAIL_PERCENT_HIWATER 20
    #define RING_AVAIL_PERCENT_LOWATER 10
    
    static inline void netvsc_free_send_slot(struct netvsc_device *net_device,
    					 u32 index)
    {
    	sync_change_bit(index, net_device->send_section_map);
    }
    
    static void netvsc_send_tx_complete(struct net_device *ndev,
    				    struct netvsc_device *net_device,
    				    struct vmbus_channel *channel,
    				    const struct vmpacket_descriptor *desc,
    				    int budget)
    {
    	struct sk_buff *skb = (struct sk_buff *)(unsigned long)desc->trans_id;
    	struct net_device_context *ndev_ctx = netdev_priv(ndev);
    	u16 q_idx = 0;
    	int queue_sends;
    
    	/* Notify the layer above us */
    	if (likely(skb)) {
    		const struct hv_netvsc_packet *packet
    			= (struct hv_netvsc_packet *)skb->cb;
    		u32 send_index = packet->send_buf_index;
    		struct netvsc_stats *tx_stats;
    
    		if (send_index != NETVSC_INVALID_INDEX)
    			netvsc_free_send_slot(net_device, send_index);
    		q_idx = packet->q_idx;
    
    		tx_stats = &net_device->chan_table[q_idx].tx_stats;
    
    		u64_stats_update_begin(&tx_stats->syncp);
    		tx_stats->packets += packet->total_packets;
    		tx_stats->bytes += packet->total_bytes;
    		u64_stats_update_end(&tx_stats->syncp);
    
    		napi_consume_skb(skb, budget);
    	}
    
    	queue_sends =
    		atomic_dec_return(&net_device->chan_table[q_idx].queue_sends);
    
    	if (unlikely(net_device->destroy)) {
    		if (queue_sends == 0)
    			wake_up(&net_device->wait_drain);
    	} else {
    		struct netdev_queue *txq = netdev_get_tx_queue(ndev, q_idx);
    
    		if (netif_tx_queue_stopped(txq) &&
    		    (hv_get_avail_to_write_percent(&channel->outbound) >
    		     RING_AVAIL_PERCENT_HIWATER || queue_sends < 1)) {
    			netif_tx_wake_queue(txq);
    			ndev_ctx->eth_stats.wake_queue++;
    		}
    	}
    }
    
    static void netvsc_send_completion(struct net_device *ndev,
    				   struct netvsc_device *net_device,
    				   struct vmbus_channel *incoming_channel,
    				   const struct vmpacket_descriptor *desc,
    				   int budget)
    {
    	const struct nvsp_message *nvsp_packet = hv_pkt_data(desc);
    
    	switch (nvsp_packet->hdr.msg_type) {
    	case NVSP_MSG_TYPE_INIT_COMPLETE:
    	case NVSP_MSG1_TYPE_SEND_RECV_BUF_COMPLETE:
    	case NVSP_MSG1_TYPE_SEND_SEND_BUF_COMPLETE:
    	case NVSP_MSG5_TYPE_SUBCHANNEL:
    		/* Copy the response back */
    		memcpy(&net_device->channel_init_pkt, nvsp_packet,
    		       sizeof(struct nvsp_message));
    		complete(&net_device->channel_init_wait);
    		break;
    
    	case NVSP_MSG1_TYPE_SEND_RNDIS_PKT_COMPLETE:
    		netvsc_send_tx_complete(ndev, net_device, incoming_channel,
    					desc, budget);
    		break;
    
    	default:
    		netdev_err(ndev,
    			   "Unknown send completion type %d received!!\n",
    			   nvsp_packet->hdr.msg_type);
    	}
    }
    
    static u32 netvsc_get_next_send_section(struct netvsc_device *net_device)
    {
    	unsigned long *map_addr = net_device->send_section_map;
    	unsigned int i;
    
    	for_each_clear_bit(i, map_addr, net_device->send_section_cnt) {
    		if (sync_test_and_set_bit(i, map_addr) == 0)
    			return i;
    	}
    
    	return NETVSC_INVALID_INDEX;
    }
    
    static void netvsc_copy_to_send_buf(struct netvsc_device *net_device,
    				    unsigned int section_index,
    				    u32 pend_size,
    				    struct hv_netvsc_packet *packet,
    				    struct rndis_message *rndis_msg,
    				    struct hv_page_buffer *pb,
    				    bool xmit_more)
    {
    	char *start = net_device->send_buf;
    	char *dest = start + (section_index * net_device->send_section_size)
    		     + pend_size;
    	int i;
    	u32 padding = 0;
    	u32 page_count = packet->cp_partial ? packet->rmsg_pgcnt :
    		packet->page_buf_cnt;
    	u32 remain;
    
    	/* Add padding */
    	remain = packet->total_data_buflen & (net_device->pkt_align - 1);
    	if (xmit_more && remain) {
    		padding = net_device->pkt_align - remain;
    		rndis_msg->msg_len += padding;
    		packet->total_data_buflen += padding;
    	}
    
    	for (i = 0; i < page_count; i++) {
    		char *src = phys_to_virt(pb[i].pfn << PAGE_SHIFT);
    		u32 offset = pb[i].offset;
    		u32 len = pb[i].len;
    
    		memcpy(dest, (src + offset), len);
    		dest += len;
    	}
    
    	if (padding)
    		memset(dest, 0, padding);
    }
    
    static inline int netvsc_send_pkt(
    	struct hv_device *device,
    	struct hv_netvsc_packet *packet,
    	struct netvsc_device *net_device,
    	struct hv_page_buffer *pb,
    	struct sk_buff *skb)
    {
    	struct nvsp_message nvmsg;
    	struct nvsp_1_message_send_rndis_packet *rpkt =
    		&nvmsg.msg.v1_msg.send_rndis_pkt;
    	struct netvsc_channel * const nvchan =
    		&net_device->chan_table[packet->q_idx];
    	struct vmbus_channel *out_channel = nvchan->channel;
    	struct net_device *ndev = hv_get_drvdata(device);
    	struct net_device_context *ndev_ctx = netdev_priv(ndev);
    	struct netdev_queue *txq = netdev_get_tx_queue(ndev, packet->q_idx);
    	u64 req_id;
    	int ret;
    	u32 ring_avail = hv_get_avail_to_write_percent(&out_channel->outbound);
    
    	nvmsg.hdr.msg_type = NVSP_MSG1_TYPE_SEND_RNDIS_PKT;
    	if (skb)
    		rpkt->channel_type = 0;		/* 0 is RMC_DATA */
    	else
    		rpkt->channel_type = 1;		/* 1 is RMC_CONTROL */
    
    	rpkt->send_buf_section_index = packet->send_buf_index;
    	if (packet->send_buf_index == NETVSC_INVALID_INDEX)
    		rpkt->send_buf_section_size = 0;
    	else
    		rpkt->send_buf_section_size = packet->total_data_buflen;
    
    	req_id = (ulong)skb;
    
    	if (out_channel->rescind)
    		return -ENODEV;
    
    	trace_nvsp_send_pkt(ndev, out_channel, rpkt);
    
    	if (packet->page_buf_cnt) {
    		if (packet->cp_partial)
    			pb += packet->rmsg_pgcnt;
    
    		ret = vmbus_sendpacket_pagebuffer(out_channel,
    						  pb, packet->page_buf_cnt,
    						  &nvmsg, sizeof(nvmsg),
    						  req_id);
    	} else {
    		ret = vmbus_sendpacket(out_channel,
    				       &nvmsg, sizeof(nvmsg),
    				       req_id, VM_PKT_DATA_INBAND,
    				       VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
    	}
    
    	if (ret == 0) {
    		atomic_inc_return(&nvchan->queue_sends);
    
    		if (ring_avail < RING_AVAIL_PERCENT_LOWATER) {
    			netif_tx_stop_queue(txq);
    			ndev_ctx->eth_stats.stop_queue++;
    		}
    	} else if (ret == -EAGAIN) {
    		netif_tx_stop_queue(txq);
    		ndev_ctx->eth_stats.stop_queue++;
    		if (atomic_read(&nvchan->queue_sends) < 1) {
    			netif_tx_wake_queue(txq);
    			ndev_ctx->eth_stats.wake_queue++;
    			ret = -ENOSPC;
    		}
    	} else {
    		netdev_err(ndev,
    			   "Unable to send packet pages %u len %u, ret %d\n",
    			   packet->page_buf_cnt, packet->total_data_buflen,
    			   ret);
    	}
    
    	return ret;
    }
    
    /* Move packet out of multi send data (msd), and clear msd */
    static inline void move_pkt_msd(struct hv_netvsc_packet **msd_send,
    				struct sk_buff **msd_skb,
    				struct multi_send_data *msdp)
    {
    	*msd_skb = msdp->skb;
    	*msd_send = msdp->pkt;
    	msdp->skb = NULL;
    	msdp->pkt = NULL;
    	msdp->count = 0;
    }
    
    /* RCU already held by caller */
    int netvsc_send(struct net_device *ndev,
    		struct hv_netvsc_packet *packet,
    		struct rndis_message *rndis_msg,
    		struct hv_page_buffer *pb,
    		struct sk_buff *skb)
    {
    	struct net_device_context *ndev_ctx = netdev_priv(ndev);
    	struct netvsc_device *net_device
    		= rcu_dereference_bh(ndev_ctx->nvdev);
    	struct hv_device *device = ndev_ctx->device_ctx;
    	int ret = 0;
    	struct netvsc_channel *nvchan;
    	u32 pktlen = packet->total_data_buflen, msd_len = 0;
    	unsigned int section_index = NETVSC_INVALID_INDEX;
    	struct multi_send_data *msdp;
    	struct hv_netvsc_packet *msd_send = NULL, *cur_send = NULL;
    	struct sk_buff *msd_skb = NULL;
    	bool try_batch, xmit_more;
    
    	/* If device is rescinded, return error and packet will get dropped. */
    	if (unlikely(!net_device || net_device->destroy))
    		return -ENODEV;
    
    	nvchan = &net_device->chan_table[packet->q_idx];
    	packet->send_buf_index = NETVSC_INVALID_INDEX;
    	packet->cp_partial = false;
    
    	/* Send control message directly without accessing msd (Multi-Send
    	 * Data) field which may be changed during data packet processing.
    	 */
    	if (!skb)
    		return netvsc_send_pkt(device, packet, net_device, pb, skb);
    
    	/* batch packets in send buffer if possible */
    	msdp = &nvchan->msd;
    	if (msdp->pkt)
    		msd_len = msdp->pkt->total_data_buflen;
    
    	try_batch =  msd_len > 0 && msdp->count < net_device->max_pkt;
    	if (try_batch && msd_len + pktlen + net_device->pkt_align <
    	    net_device->send_section_size) {
    		section_index = msdp->pkt->send_buf_index;
    
    	} else if (try_batch && msd_len + packet->rmsg_size <
    		   net_device->send_section_size) {
    		section_index = msdp->pkt->send_buf_index;
    		packet->cp_partial = true;
    
    	} else if (pktlen + net_device->pkt_align <
    		   net_device->send_section_size) {
    		section_index = netvsc_get_next_send_section(net_device);
    		if (unlikely(section_index == NETVSC_INVALID_INDEX)) {
    			++ndev_ctx->eth_stats.tx_send_full;
    		} else {
    			move_pkt_msd(&msd_send, &msd_skb, msdp);
    			msd_len = 0;
    		}
    	}
    
    	/* Keep aggregating only if stack says more data is coming
    	 * and not doing mixed modes send and not flow blocked
    	 */
    	xmit_more = skb->xmit_more &&
    		!packet->cp_partial &&
    		!netif_xmit_stopped(netdev_get_tx_queue(ndev, packet->q_idx));
    
    	if (section_index != NETVSC_INVALID_INDEX) {
    		netvsc_copy_to_send_buf(net_device,
    					section_index, msd_len,
    					packet, rndis_msg, pb, xmit_more);
    
    		packet->send_buf_index = section_index;
    
    		if (packet->cp_partial) {
    			packet->page_buf_cnt -= packet->rmsg_pgcnt;
    			packet->total_data_buflen = msd_len + packet->rmsg_size;
    		} else {
    			packet->page_buf_cnt = 0;
    			packet->total_data_buflen += msd_len;
    		}
    
    		if (msdp->pkt) {
    			packet->total_packets += msdp->pkt->total_packets;
    			packet->total_bytes += msdp->pkt->total_bytes;
    		}
    
    		if (msdp->skb)
    			dev_consume_skb_any(msdp->skb);
    
    		if (xmit_more) {
    			msdp->skb = skb;
    			msdp->pkt = packet;
    			msdp->count++;
    		} else {
    			cur_send = packet;
    			msdp->skb = NULL;
    			msdp->pkt = NULL;
    			msdp->count = 0;
    		}
    	} else {
    		move_pkt_msd(&msd_send, &msd_skb, msdp);
    		cur_send = packet;
    	}
    
    	if (msd_send) {
    		int m_ret = netvsc_send_pkt(device, msd_send, net_device,
    					    NULL, msd_skb);
    
    		if (m_ret != 0) {
    			netvsc_free_send_slot(net_device,
    					      msd_send->send_buf_index);
    			dev_kfree_skb_any(msd_skb);
    		}
    	}
    
    	if (cur_send)
    		ret = netvsc_send_pkt(device, cur_send, net_device, pb, skb);
    
    	if (ret != 0 && section_index != NETVSC_INVALID_INDEX)
    		netvsc_free_send_slot(net_device, section_index);
    
    	return ret;
    }
    
    /* Send pending recv completions */
    static int send_recv_completions(struct net_device *ndev,
    				 struct netvsc_device *nvdev,
    				 struct netvsc_channel *nvchan)
    {
    	struct multi_recv_comp *mrc = &nvchan->mrc;
    	struct recv_comp_msg {
    		struct nvsp_message_header hdr;
    		u32 status;
    	}  __packed;
    	struct recv_comp_msg msg = {
    		.hdr.msg_type = NVSP_MSG1_TYPE_SEND_RNDIS_PKT_COMPLETE,
    	};
    	int ret;
    
    	while (mrc->first != mrc->next) {
    		const struct recv_comp_data *rcd
    			= mrc->slots + mrc->first;
    
    		msg.status = rcd->status;
    		ret = vmbus_sendpacket(nvchan->channel, &msg, sizeof(msg),
    				       rcd->tid, VM_PKT_COMP, 0);
    		if (unlikely(ret)) {
    			struct net_device_context *ndev_ctx = netdev_priv(ndev);
    
    			++ndev_ctx->eth_stats.rx_comp_busy;
    			return ret;
    		}
    
    		if (++mrc->first == nvdev->recv_completion_cnt)
    			mrc->first = 0;
    	}
    
    	/* receive completion ring has been emptied */
    	if (unlikely(nvdev->destroy))
    		wake_up(&nvdev->wait_drain);
    
    	return 0;
    }
    
    /* Count how many receive completions are outstanding */
    static void recv_comp_slot_avail(const struct netvsc_device *nvdev,
    				 const struct multi_recv_comp *mrc,
    				 u32 *filled, u32 *avail)
    {
    	u32 count = nvdev->recv_completion_cnt;
    
    	if (mrc->next >= mrc->first)
    		*filled = mrc->next - mrc->first;
    	else
    		*filled = (count - mrc->first) + mrc->next;
    
    	*avail = count - *filled - 1;
    }
    
    /* Add receive complete to ring to send to host. */
    static void enq_receive_complete(struct net_device *ndev,
    				 struct netvsc_device *nvdev, u16 q_idx,
    				 u64 tid, u32 status)
    {
    	struct netvsc_channel *nvchan = &nvdev->chan_table[q_idx];
    	struct multi_recv_comp *mrc = &nvchan->mrc;
    	struct recv_comp_data *rcd;
    	u32 filled, avail;
    
    	recv_comp_slot_avail(nvdev, mrc, &filled, &avail);
    
    	if (unlikely(filled > NAPI_POLL_WEIGHT)) {
    		send_recv_completions(ndev, nvdev, nvchan);
    		recv_comp_slot_avail(nvdev, mrc, &filled, &avail);
    	}
    
    	if (unlikely(!avail)) {
    		netdev_err(ndev, "Recv_comp full buf q:%hd, tid:%llx\n",
    			   q_idx, tid);
    		return;
    	}
    
    	rcd = mrc->slots + mrc->next;
    	rcd->tid = tid;
    	rcd->status = status;
    
    	if (++mrc->next == nvdev->recv_completion_cnt)
    		mrc->next = 0;
    }
    
    static int netvsc_receive(struct net_device *ndev,
    			  struct netvsc_device *net_device,
    			  struct vmbus_channel *channel,
    			  const struct vmpacket_descriptor *desc,
    			  const struct nvsp_message *nvsp)
    {
    	struct net_device_context *net_device_ctx = netdev_priv(ndev);
    	const struct vmtransfer_page_packet_header *vmxferpage_packet
    		= container_of(desc, const struct vmtransfer_page_packet_header, d);
    	u16 q_idx = channel->offermsg.offer.sub_channel_index;
    	char *recv_buf = net_device->recv_buf;
    	u32 status = NVSP_STAT_SUCCESS;
    	int i;
    	int count = 0;
    
    	/* Make sure this is a valid nvsp packet */
    	if (unlikely(nvsp->hdr.msg_type != NVSP_MSG1_TYPE_SEND_RNDIS_PKT)) {
    		netif_err(net_device_ctx, rx_err, ndev,
    			  "Unknown nvsp packet type received %u\n",
    			  nvsp->hdr.msg_type);
    		return 0;
    	}
    
    	if (unlikely(vmxferpage_packet->xfer_pageset_id != NETVSC_RECEIVE_BUFFER_ID)) {
    		netif_err(net_device_ctx, rx_err, ndev,
    			  "Invalid xfer page set id - expecting %x got %x\n",
    			  NETVSC_RECEIVE_BUFFER_ID,
    			  vmxferpage_packet->xfer_pageset_id);
    		return 0;
    	}
    
    	count = vmxferpage_packet->range_cnt;
    
    	/* Each range represents 1 RNDIS pkt that contains 1 ethernet frame */
    	for (i = 0; i < count; i++) {
    		u32 offset = vmxferpage_packet->ranges[i].byte_offset;
    		u32 buflen = vmxferpage_packet->ranges[i].byte_count;
    		void *data;
    		int ret;
    
    		if (unlikely(offset + buflen > net_device->recv_buf_size)) {
    			status = NVSP_STAT_FAIL;
    			netif_err(net_device_ctx, rx_err, ndev,
    				  "Packet offset:%u + len:%u too big\n",
    				  offset, buflen);
    
    			continue;
    		}
    
    		data = recv_buf + offset;
    
    		trace_rndis_recv(ndev, q_idx, data);
    
    		/* Pass it to the upper layer */
    		ret = rndis_filter_receive(ndev, net_device,
    					   channel, data, buflen);
    
    		if (unlikely(ret != NVSP_STAT_SUCCESS))
    			status = NVSP_STAT_FAIL;
    	}
    
    	enq_receive_complete(ndev, net_device, q_idx,
    			     vmxferpage_packet->d.trans_id, status);
    
    	return count;
    }
    
    static void netvsc_send_table(struct net_device *ndev,
    			      const struct nvsp_message *nvmsg)
    {
    	struct net_device_context *net_device_ctx = netdev_priv(ndev);
    	u32 count, *tab;
    	int i;
    
    	count = nvmsg->msg.v5_msg.send_table.count;
    	if (count != VRSS_SEND_TAB_SIZE) {
    		netdev_err(ndev, "Received wrong send-table size:%u\n", count);
    		return;
    	}
    
    	tab = (u32 *)((unsigned long)&nvmsg->msg.v5_msg.send_table +
    		      nvmsg->msg.v5_msg.send_table.offset);
    
    	for (i = 0; i < count; i++)
    		net_device_ctx->tx_table[i] = tab[i];
    }
    
    static void netvsc_send_vf(struct net_device *ndev,
    			   const struct nvsp_message *nvmsg)
    {
    	struct net_device_context *net_device_ctx = netdev_priv(ndev);
    
    	net_device_ctx->vf_alloc = nvmsg->msg.v4_msg.vf_assoc.allocated;
    	net_device_ctx->vf_serial = nvmsg->msg.v4_msg.vf_assoc.serial;
    	netdev_info(ndev, "VF slot %u %s\n",
    		    net_device_ctx->vf_serial,
    		    net_device_ctx->vf_alloc ? "added" : "removed");
    }
    
    static  void netvsc_receive_inband(struct net_device *ndev,
    				   const struct nvsp_message *nvmsg)
    {
    	switch (nvmsg->hdr.msg_type) {
    	case NVSP_MSG5_TYPE_SEND_INDIRECTION_TABLE:
    		netvsc_send_table(ndev, nvmsg);
    		break;
    
    	case NVSP_MSG4_TYPE_SEND_VF_ASSOCIATION:
    		netvsc_send_vf(ndev, nvmsg);
    		break;
    	}
    }
    
    static int netvsc_process_raw_pkt(struct hv_device *device,
    				  struct vmbus_channel *channel,
    				  struct netvsc_device *net_device,
    				  struct net_device *ndev,
    				  const struct vmpacket_descriptor *desc,
    				  int budget)
    {
    	const struct nvsp_message *nvmsg = hv_pkt_data(desc);
    
    	trace_nvsp_recv(ndev, channel, nvmsg);
    
    	switch (desc->type) {
    	case VM_PKT_COMP:
    		netvsc_send_completion(ndev, net_device, channel,
    				       desc, budget);
    		break;
    
    	case VM_PKT_DATA_USING_XFER_PAGES:
    		return netvsc_receive(ndev, net_device, channel,
    				      desc, nvmsg);
    		break;
    
    	case VM_PKT_DATA_INBAND:
    		netvsc_receive_inband(ndev, nvmsg);
    		break;
    
    	default:
    		netdev_err(ndev, "unhandled packet type %d, tid %llx\n",
    			   desc->type, desc->trans_id);
    		break;
    	}
    
    	return 0;
    }
    
    static struct hv_device *netvsc_channel_to_device(struct vmbus_channel *channel)
    {
    	struct vmbus_channel *primary = channel->primary_channel;
    
    	return primary ? primary->device_obj : channel->device_obj;
    }
    
    /* Network processing softirq
     * Process data in incoming ring buffer from host
     * Stops when ring is empty or budget is met or exceeded.
     */
    int netvsc_poll(struct napi_struct *napi, int budget)
    {
    	struct netvsc_channel *nvchan
    		= container_of(napi, struct netvsc_channel, napi);
    	struct netvsc_device *net_device = nvchan->net_device;
    	struct vmbus_channel *channel = nvchan->channel;
    	struct hv_device *device = netvsc_channel_to_device(channel);
    	struct net_device *ndev = hv_get_drvdata(device);
    	int work_done = 0;
    	int ret;
    
    	/* If starting a new interval */
    	if (!nvchan->desc)
    		nvchan->desc = hv_pkt_iter_first(channel);
    
    	while (nvchan->desc && work_done < budget) {
    		work_done += netvsc_process_raw_pkt(device, channel, net_device,
    						    ndev, nvchan->desc, budget);
    		nvchan->desc = hv_pkt_iter_next(channel, nvchan->desc);
    	}
    
    	/* Send any pending receive completions */
    	ret = send_recv_completions(ndev, net_device, nvchan);
    
    	/* If it did not exhaust NAPI budget this time
    	 *  and not doing busy poll
    	 * then re-enable host interrupts
    	 *  and reschedule if ring is not empty
    	 *   or sending receive completion failed.
    	 */
    	if (work_done < budget &&
    	    napi_complete_done(napi, work_done) &&
    	    (ret || hv_end_read(&channel->inbound)) &&
    	    napi_schedule_prep(napi)) {
    		hv_begin_read(&channel->inbound);
    		__napi_schedule(napi);
    	}
    
    	/* Driver may overshoot since multiple packets per descriptor */
    	return min(work_done, budget);
    }
    
    /* Call back when data is available in host ring buffer.
     * Processing is deferred until network softirq (NAPI)
     */
    void netvsc_channel_cb(void *context)
    {
    	struct netvsc_channel *nvchan = context;
    	struct vmbus_channel *channel = nvchan->channel;
    	struct hv_ring_buffer_info *rbi = &channel->inbound;
    
    	/* preload first vmpacket descriptor */
    	prefetch(hv_get_ring_buffer(rbi) + rbi->priv_read_index);
    
    	if (napi_schedule_prep(&nvchan->napi)) {
    		/* disable interupts from host */
    		hv_begin_read(rbi);
    
    		__napi_schedule_irqoff(&nvchan->napi);
    	}
    }
    
    /*
     * netvsc_device_add - Callback when the device belonging to this
     * driver is added
     */
    struct netvsc_device *netvsc_device_add(struct hv_device *device,
    				const struct netvsc_device_info *device_info)
    {
    	int i, ret = 0;
    	struct netvsc_device *net_device;
    	struct net_device *ndev = hv_get_drvdata(device);
    	struct net_device_context *net_device_ctx = netdev_priv(ndev);
    
    	net_device = alloc_net_device();
    	if (!net_device)
    		return ERR_PTR(-ENOMEM);
    
    	for (i = 0; i < VRSS_SEND_TAB_SIZE; i++)
    		net_device_ctx->tx_table[i] = 0;
    
    	/* Because the device uses NAPI, all the interrupt batching and
    	 * control is done via Net softirq, not the channel handling
    	 */
    	set_channel_read_mode(device->channel, HV_CALL_ISR);
    
    	/* If we're reopening the device we may have multiple queues, fill the
    	 * chn_table with the default channel to use it before subchannels are
    	 * opened.
    	 * Initialize the channel state before we open;
    	 * we can be interrupted as soon as we open the channel.
    	 */
    
    	for (i = 0; i < VRSS_CHANNEL_MAX; i++) {
    		struct netvsc_channel *nvchan = &net_device->chan_table[i];
    
    		nvchan->channel = device->channel;
    		nvchan->net_device = net_device;
    		u64_stats_init(&nvchan->tx_stats.syncp);
    		u64_stats_init(&nvchan->rx_stats.syncp);
    	}
    
    	/* Enable NAPI handler before init callbacks */
    	netif_napi_add(ndev, &net_device->chan_table[0].napi,
    		       netvsc_poll, NAPI_POLL_WEIGHT);
    
    	/* Open the channel */
    	ret = vmbus_open(device->channel, netvsc_ring_bytes,
    			 netvsc_ring_bytes,  NULL, 0,
    			 netvsc_channel_cb, net_device->chan_table);
    
    	if (ret != 0) {
    		netdev_err(ndev, "unable to open channel: %d\n", ret);
    		goto cleanup;
    	}
    
    	/* Channel is opened */
    	netdev_dbg(ndev, "hv_netvsc channel opened successfully\n");
    
    	napi_enable(&net_device->chan_table[0].napi);
    
    	/* Connect with the NetVsp */
    	ret = netvsc_connect_vsp(device, net_device, device_info);
    	if (ret != 0) {
    		netdev_err(ndev,
    			"unable to connect to NetVSP - %d\n", ret);
    		goto close;
    	}
    
    	/* Writing nvdev pointer unlocks netvsc_send(), make sure chn_table is
    	 * populated.
    	 */
    	rcu_assign_pointer(net_device_ctx->nvdev, net_device);
    
    	return net_device;
    
    close:
    	RCU_INIT_POINTER(net_device_ctx->nvdev, NULL);
    	napi_disable(&net_device->chan_table[0].napi);
    
    	/* Now, we can close the channel safely */
    	vmbus_close(device->channel);
    
    cleanup:
    	netif_napi_del(&net_device->chan_table[0].napi);
    	free_netvsc_device(&net_device->rcu);
    
    	return ERR_PTR(ret);
    }