drivers/hv/channel_mgmt.c - kernel/msm-4.9 - Gitiles

 /*
  * 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>
  */
 #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/slab.h>
 #include <linux/list.h>
 #include <linux/module.h>
 #include <linux/completion.h>
 #include <linux/hyperv.h>

 #include "hyperv_vmbus.h"

 struct vmbus_channel_message_table_entry {
 	enum vmbus_channel_message_type message_type;
 	void (*message_handler)(struct vmbus_channel_message_header *msg);
 };


 /**
  * vmbus_prep_negotiate_resp() - Create default response for Hyper-V Negotiate message
  * @icmsghdrp: Pointer to msg header structure
  * @icmsg_negotiate: Pointer to negotiate message structure
  * @buf: Raw buffer channel data
  *
  * @icmsghdrp is of type &struct icmsg_hdr.
  * @negop is of type &struct icmsg_negotiate.
  * Set up and fill in default negotiate response message.
  *
  * The max_fw_version specifies the maximum framework version that
  * we can support and max _srv_version specifies the maximum service
  * version we can support. A special value MAX_SRV_VER can be
  * specified to indicate that we can handle the maximum version
  * exposed by the host.
  *
  * Mainly used by Hyper-V drivers.
  */
 void vmbus_prep_negotiate_resp(struct icmsg_hdr *icmsghdrp,
 				struct icmsg_negotiate *negop, u8 *buf,
 				int max_fw_version, int max_srv_version)
 {
 	int icframe_vercnt;
 	int icmsg_vercnt;
 	int i;

 	icmsghdrp->icmsgsize = 0x10;

 	negop = (struct icmsg_negotiate *)&buf[
 		sizeof(struct vmbuspipe_hdr) +
 		sizeof(struct icmsg_hdr)];

 	icframe_vercnt = negop->icframe_vercnt;
 	icmsg_vercnt = negop->icmsg_vercnt;

 	/*
 	 * Select the framework version number we will
 	 * support.
 	 */

 	for (i = 0; i < negop->icframe_vercnt; i++) {
 		if (negop->icversion_data[i].major <= max_fw_version)
 			icframe_vercnt = negop->icversion_data[i].major;
 	}

 	for (i = negop->icframe_vercnt;
 		 (i < negop->icframe_vercnt + negop->icmsg_vercnt); i++) {
 		if (negop->icversion_data[i].major <= max_srv_version)
 			icmsg_vercnt = negop->icversion_data[i].major;
 	}

 	/*
 	 * Respond with the maximum framework and service
 	 * version numbers we can support.
 	 */
 	negop->icframe_vercnt = 1;
 	negop->icmsg_vercnt = 1;
 	negop->icversion_data[0].major = icframe_vercnt;
 	negop->icversion_data[0].minor = 0;
 	negop->icversion_data[1].major = icmsg_vercnt;
 	negop->icversion_data[1].minor = 0;
 }

 EXPORT_SYMBOL_GPL(vmbus_prep_negotiate_resp);

 /*
  * alloc_channel - Allocate and initialize a vmbus channel object
  */
 static struct vmbus_channel *alloc_channel(void)
 {
 	struct vmbus_channel *channel;

 	channel = kzalloc(sizeof(*channel), GFP_ATOMIC);
 	if (!channel)
 		return NULL;

 	spin_lock_init(&channel->inbound_lock);

 	channel->controlwq = create_workqueue("hv_vmbus_ctl");
 	if (!channel->controlwq) {
 		kfree(channel);
 		return NULL;
 	}

 	return channel;
 }

 /*
  * release_hannel - Release the vmbus channel object itself
  */
 static void release_channel(struct work_struct *work)
 {
 	struct vmbus_channel *channel = container_of(work,
 						     struct vmbus_channel,
 						     work);

 	destroy_workqueue(channel->controlwq);

 	kfree(channel);
 }

 /*
  * free_channel - Release the resources used by the vmbus channel object
  */
 static void free_channel(struct vmbus_channel *channel)
 {

 	/*
 	 * We have to release the channel's workqueue/thread in the vmbus's
 	 * workqueue/thread context
 	 * ie we can't destroy ourselves.
 	 */
 	INIT_WORK(&channel->work, release_channel);
 	queue_work(vmbus_connection.work_queue, &channel->work);
 }


 /*
  * vmbus_process_rescind_offer -
  * Rescind the offer by initiating a device removal
  */
 static void vmbus_process_rescind_offer(struct work_struct *work)
 {
 	struct vmbus_channel *channel = container_of(work,
 						     struct vmbus_channel,
 						     work);

 	vmbus_device_unregister(channel->device_obj);
 }

 void vmbus_free_channels(void)
 {
 	struct vmbus_channel *channel;

 	list_for_each_entry(channel, &vmbus_connection.chn_list, listentry) {
 		vmbus_device_unregister(channel->device_obj);
 		kfree(channel->device_obj);
 		free_channel(channel);
 	}
 }

 /*
  * vmbus_process_offer - Process the offer by creating a channel/device
  * associated with this offer
  */
 static void vmbus_process_offer(struct work_struct *work)
 {
 	struct vmbus_channel *newchannel = container_of(work,
 							struct vmbus_channel,
 							work);
 	struct vmbus_channel *channel;
 	bool fnew = true;
 	int ret;
 	unsigned long flags;

 	/* The next possible work is rescind handling */
 	INIT_WORK(&newchannel->work, vmbus_process_rescind_offer);

 	/* Make sure this is a new offer */
 	spin_lock_irqsave(&vmbus_connection.channel_lock, flags);

 	list_for_each_entry(channel, &vmbus_connection.chn_list, listentry) {
 		if (!uuid_le_cmp(channel->offermsg.offer.if_type,
 			newchannel->offermsg.offer.if_type) &&
 			!uuid_le_cmp(channel->offermsg.offer.if_instance,
 				newchannel->offermsg.offer.if_instance)) {
 			fnew = false;
 			break;
 		}
 	}

 	if (fnew)
 		list_add_tail(&newchannel->listentry,
 			      &vmbus_connection.chn_list);

 	spin_unlock_irqrestore(&vmbus_connection.channel_lock, flags);

 	if (!fnew) {
 		free_channel(newchannel);
 		return;
 	}

 	/*
 	 * Start the process of binding this offer to the driver
 	 * We need to set the DeviceObject field before calling
 	 * vmbus_child_dev_add()
 	 */
 	newchannel->device_obj = vmbus_device_create(
 		&newchannel->offermsg.offer.if_type,
 		&newchannel->offermsg.offer.if_instance,
 		newchannel);

 	/*
 	 * Add the new device to the bus. This will kick off device-driver
 	 * binding which eventually invokes the device driver's AddDevice()
 	 * method.
 	 */
 	ret = vmbus_device_register(newchannel->device_obj);
 	if (ret != 0) {
 		pr_err("unable to add child device object (relid %d)\n",
 			   newchannel->offermsg.child_relid);

 		spin_lock_irqsave(&vmbus_connection.channel_lock, flags);
 		list_del(&newchannel->listentry);
 		spin_unlock_irqrestore(&vmbus_connection.channel_lock, flags);
 		kfree(newchannel->device_obj);

 		free_channel(newchannel);
 	} else {
 		/*
 		 * This state is used to indicate a successful open
 		 * so that when we do close the channel normally, we
 		 * can cleanup properly
 		 */
 		newchannel->state = CHANNEL_OPEN_STATE;
 	}
 }

 /*
  * vmbus_onoffer - Handler for channel offers from vmbus in parent partition.
  *
  */
 static void vmbus_onoffer(struct vmbus_channel_message_header *hdr)
 {
 	struct vmbus_channel_offer_channel *offer;
 	struct vmbus_channel *newchannel;
 	uuid_le *guidtype;
 	uuid_le *guidinstance;

 	offer = (struct vmbus_channel_offer_channel *)hdr;

 	guidtype = &offer->offer.if_type;
 	guidinstance = &offer->offer.if_instance;

 	/* Allocate the channel object and save this offer. */
 	newchannel = alloc_channel();
 	if (!newchannel) {
 		pr_err("Unable to allocate channel object\n");
 		return;
 	}

 	memcpy(&newchannel->offermsg, offer,
 	       sizeof(struct vmbus_channel_offer_channel));
 	newchannel->monitor_grp = (u8)offer->monitorid / 32;
 	newchannel->monitor_bit = (u8)offer->monitorid % 32;

 	INIT_WORK(&newchannel->work, vmbus_process_offer);
 	queue_work(newchannel->controlwq, &newchannel->work);
 }

 /*
  * vmbus_onoffer_rescind - Rescind offer handler.
  *
  * We queue a work item to process this offer synchronously
  */
 static void vmbus_onoffer_rescind(struct vmbus_channel_message_header *hdr)
 {
 	struct vmbus_channel_rescind_offer *rescind;
 	struct vmbus_channel *channel;

 	rescind = (struct vmbus_channel_rescind_offer *)hdr;
 	channel = relid2channel(rescind->child_relid);

 	if (channel == NULL)
 		/* Just return here, no channel found */
 		return;

 	/* work is initialized for vmbus_process_rescind_offer() from
 	 * vmbus_process_offer() where the channel got created */
 	queue_work(channel->controlwq, &channel->work);
 }

 /*
  * vmbus_onoffers_delivered -
  * This is invoked when all offers have been delivered.
  *
  * Nothing to do here.
  */
 static void vmbus_onoffers_delivered(
 			struct vmbus_channel_message_header *hdr)
 {
 }

 /*
  * vmbus_onopen_result - Open result handler.
  *
  * This is invoked when we received a response to our channel open request.
  * Find the matching request, copy the response and signal the requesting
  * thread.
  */
 static void vmbus_onopen_result(struct vmbus_channel_message_header *hdr)
 {
 	struct vmbus_channel_open_result *result;
 	struct vmbus_channel_msginfo *msginfo;
 	struct vmbus_channel_message_header *requestheader;
 	struct vmbus_channel_open_channel *openmsg;
 	unsigned long flags;

 	result = (struct vmbus_channel_open_result *)hdr;

 	/*
 	 * Find the open msg, copy the result and signal/unblock the wait event
 	 */
 	spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);

 	list_for_each_entry(msginfo, &vmbus_connection.chn_msg_list,
 				msglistentry) {
 		requestheader =
 			(struct vmbus_channel_message_header *)msginfo->msg;

 		if (requestheader->msgtype == CHANNELMSG_OPENCHANNEL) {
 			openmsg =
 			(struct vmbus_channel_open_channel *)msginfo->msg;
 			if (openmsg->child_relid == result->child_relid &&
 			    openmsg->openid == result->openid) {
 				memcpy(&msginfo->response.open_result,
 				       result,
 				       sizeof(
 					struct vmbus_channel_open_result));
 				complete(&msginfo->waitevent);
 				break;
 			}
 		}
 	}
 	spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
 }

 /*
  * vmbus_ongpadl_created - GPADL created handler.
  *
  * This is invoked when we received a response to our gpadl create request.
  * Find the matching request, copy the response and signal the requesting
  * thread.
  */
 static void vmbus_ongpadl_created(struct vmbus_channel_message_header *hdr)
 {
 	struct vmbus_channel_gpadl_created *gpadlcreated;
 	struct vmbus_channel_msginfo *msginfo;
 	struct vmbus_channel_message_header *requestheader;
 	struct vmbus_channel_gpadl_header *gpadlheader;
 	unsigned long flags;

 	gpadlcreated = (struct vmbus_channel_gpadl_created *)hdr;

 	/*
 	 * Find the establish msg, copy the result and signal/unblock the wait
 	 * event
 	 */
 	spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);

 	list_for_each_entry(msginfo, &vmbus_connection.chn_msg_list,
 				msglistentry) {
 		requestheader =
 			(struct vmbus_channel_message_header *)msginfo->msg;

 		if (requestheader->msgtype == CHANNELMSG_GPADL_HEADER) {
 			gpadlheader =
 			(struct vmbus_channel_gpadl_header *)requestheader;

 			if ((gpadlcreated->child_relid ==
 			     gpadlheader->child_relid) &&
 			    (gpadlcreated->gpadl == gpadlheader->gpadl)) {
 				memcpy(&msginfo->response.gpadl_created,
 				       gpadlcreated,
 				       sizeof(
 					struct vmbus_channel_gpadl_created));
 				complete(&msginfo->waitevent);
 				break;
 			}
 		}
 	}
 	spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
 }

 /*
  * vmbus_ongpadl_torndown - GPADL torndown handler.
  *
  * This is invoked when we received a response to our gpadl teardown request.
  * Find the matching request, copy the response and signal the requesting
  * thread.
  */
 static void vmbus_ongpadl_torndown(
 			struct vmbus_channel_message_header *hdr)
 {
 	struct vmbus_channel_gpadl_torndown *gpadl_torndown;
 	struct vmbus_channel_msginfo *msginfo;
 	struct vmbus_channel_message_header *requestheader;
 	struct vmbus_channel_gpadl_teardown *gpadl_teardown;
 	unsigned long flags;

 	gpadl_torndown = (struct vmbus_channel_gpadl_torndown *)hdr;

 	/*
 	 * Find the open msg, copy the result and signal/unblock the wait event
 	 */
 	spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);

 	list_for_each_entry(msginfo, &vmbus_connection.chn_msg_list,
 				msglistentry) {
 		requestheader =
 			(struct vmbus_channel_message_header *)msginfo->msg;

 		if (requestheader->msgtype == CHANNELMSG_GPADL_TEARDOWN) {
 			gpadl_teardown =
 			(struct vmbus_channel_gpadl_teardown *)requestheader;

 			if (gpadl_torndown->gpadl == gpadl_teardown->gpadl) {
 				memcpy(&msginfo->response.gpadl_torndown,
 				       gpadl_torndown,
 				       sizeof(
 					struct vmbus_channel_gpadl_torndown));
 				complete(&msginfo->waitevent);
 				break;
 			}
 		}
 	}
 	spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
 }

 /*
  * vmbus_onversion_response - Version response handler
  *
  * This is invoked when we received a response to our initiate contact request.
  * Find the matching request, copy the response and signal the requesting
  * thread.
  */
 static void vmbus_onversion_response(
 		struct vmbus_channel_message_header *hdr)
 {
 	struct vmbus_channel_msginfo *msginfo;
 	struct vmbus_channel_message_header *requestheader;
 	struct vmbus_channel_initiate_contact *initiate;
 	struct vmbus_channel_version_response *version_response;
 	unsigned long flags;

 	version_response = (struct vmbus_channel_version_response *)hdr;
 	spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);

 	list_for_each_entry(msginfo, &vmbus_connection.chn_msg_list,
 				msglistentry) {
 		requestheader =
 			(struct vmbus_channel_message_header *)msginfo->msg;

 		if (requestheader->msgtype ==
 		    CHANNELMSG_INITIATE_CONTACT) {
 			initiate =
 			(struct vmbus_channel_initiate_contact *)requestheader;
 			memcpy(&msginfo->response.version_response,
 			      version_response,
 			      sizeof(struct vmbus_channel_version_response));
 			complete(&msginfo->waitevent);
 		}
 	}
 	spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
 }

 /* Channel message dispatch table */
 static struct vmbus_channel_message_table_entry
 	channel_message_table[CHANNELMSG_COUNT] = {
 	{CHANNELMSG_INVALID,			NULL},
 	{CHANNELMSG_OFFERCHANNEL,		vmbus_onoffer},
 	{CHANNELMSG_RESCIND_CHANNELOFFER,	vmbus_onoffer_rescind},
 	{CHANNELMSG_REQUESTOFFERS,		NULL},
 	{CHANNELMSG_ALLOFFERS_DELIVERED,	vmbus_onoffers_delivered},
 	{CHANNELMSG_OPENCHANNEL,		NULL},
 	{CHANNELMSG_OPENCHANNEL_RESULT,	vmbus_onopen_result},
 	{CHANNELMSG_CLOSECHANNEL,		NULL},
 	{CHANNELMSG_GPADL_HEADER,		NULL},
 	{CHANNELMSG_GPADL_BODY,		NULL},
 	{CHANNELMSG_GPADL_CREATED,		vmbus_ongpadl_created},
 	{CHANNELMSG_GPADL_TEARDOWN,		NULL},
 	{CHANNELMSG_GPADL_TORNDOWN,		vmbus_ongpadl_torndown},
 	{CHANNELMSG_RELID_RELEASED,		NULL},
 	{CHANNELMSG_INITIATE_CONTACT,		NULL},
 	{CHANNELMSG_VERSION_RESPONSE,		vmbus_onversion_response},
 	{CHANNELMSG_UNLOAD,			NULL},
 };

 /*
  * vmbus_onmessage - Handler for channel protocol messages.
  *
  * This is invoked in the vmbus worker thread context.
  */
 void vmbus_onmessage(void *context)
 {
 	struct hv_message *msg = context;
 	struct vmbus_channel_message_header *hdr;
 	int size;

 	hdr = (struct vmbus_channel_message_header *)msg->u.payload;
 	size = msg->header.payload_size;

 	if (hdr->msgtype >= CHANNELMSG_COUNT) {
 		pr_err("Received invalid channel message type %d size %d\n",
 			   hdr->msgtype, size);
 		print_hex_dump_bytes("", DUMP_PREFIX_NONE,
 				     (unsigned char *)msg->u.payload, size);
 		return;
 	}

 	if (channel_message_table[hdr->msgtype].message_handler)
 		channel_message_table[hdr->msgtype].message_handler(hdr);
 	else
 		pr_err("Unhandled channel message type %d\n", hdr->msgtype);
 }

 /*
  * vmbus_request_offers - Send a request to get all our pending offers.
  */
 int vmbus_request_offers(void)
 {
 	struct vmbus_channel_message_header *msg;
 	struct vmbus_channel_msginfo *msginfo;
 	int ret, t;

 	msginfo = kmalloc(sizeof(*msginfo) +
 			  sizeof(struct vmbus_channel_message_header),
 			  GFP_KERNEL);
 	if (!msginfo)
 		return -ENOMEM;

 	init_completion(&msginfo->waitevent);

 	msg = (struct vmbus_channel_message_header *)msginfo->msg;

 	msg->msgtype = CHANNELMSG_REQUESTOFFERS;


 	ret = vmbus_post_msg(msg,
 			       sizeof(struct vmbus_channel_message_header));
 	if (ret != 0) {
 		pr_err("Unable to request offers - %d\n", ret);

 		goto cleanup;
 	}

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


 cleanup:
 	kfree(msginfo);

 	return ret;
 }

 /* eof */
	/*
	* 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>
	*/
	#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/slab.h>
	#include <linux/list.h>
	#include <linux/module.h>
	#include <linux/completion.h>
	#include <linux/hyperv.h>

	#include "hyperv_vmbus.h"

	struct vmbus_channel_message_table_entry {
	enum vmbus_channel_message_type message_type;
	void (message_handler)(struct vmbus_channel_message_header msg);
	};


	/**
	* vmbus_prep_negotiate_resp() - Create default response for Hyper-V Negotiate message
	* @icmsghdrp: Pointer to msg header structure
	* @icmsg_negotiate: Pointer to negotiate message structure
	* @buf: Raw buffer channel data
	*
	* @icmsghdrp is of type &struct icmsg_hdr.
	* @negop is of type &struct icmsg_negotiate.
	* Set up and fill in default negotiate response message.
	*
	* The max_fw_version specifies the maximum framework version that
	* we can support and max _srv_version specifies the maximum service
	* version we can support. A special value MAX_SRV_VER can be
	* specified to indicate that we can handle the maximum version
	* exposed by the host.
	*
	* Mainly used by Hyper-V drivers.
	*/
	void vmbus_prep_negotiate_resp(struct icmsg_hdr *icmsghdrp,
	struct icmsg_negotiate negop, u8 buf,
	int max_fw_version, int max_srv_version)
	{
	int icframe_vercnt;
	int icmsg_vercnt;
	int i;

	icmsghdrp->icmsgsize = 0x10;

	negop = (struct icmsg_negotiate *)&buf[
	sizeof(struct vmbuspipe_hdr) +
	sizeof(struct icmsg_hdr)];

	icframe_vercnt = negop->icframe_vercnt;
	icmsg_vercnt = negop->icmsg_vercnt;

	/*
	* Select the framework version number we will
	* support.
	*/

	for (i = 0; i < negop->icframe_vercnt; i++) {
	if (negop->icversion_data[i].major <= max_fw_version)
	icframe_vercnt = negop->icversion_data[i].major;
	}

	for (i = negop->icframe_vercnt;
	(i < negop->icframe_vercnt + negop->icmsg_vercnt); i++) {
	if (negop->icversion_data[i].major <= max_srv_version)
	icmsg_vercnt = negop->icversion_data[i].major;
	}

	/*
	* Respond with the maximum framework and service
	* version numbers we can support.
	*/
	negop->icframe_vercnt = 1;
	negop->icmsg_vercnt = 1;
	negop->icversion_data[0].major = icframe_vercnt;
	negop->icversion_data[0].minor = 0;
	negop->icversion_data[1].major = icmsg_vercnt;
	negop->icversion_data[1].minor = 0;
	}

	EXPORT_SYMBOL_GPL(vmbus_prep_negotiate_resp);

	/*
	* alloc_channel - Allocate and initialize a vmbus channel object
	*/
	static struct vmbus_channel *alloc_channel(void)
	{
	struct vmbus_channel *channel;

	channel = kzalloc(sizeof(*channel), GFP_ATOMIC);
	if (!channel)
	return NULL;

	spin_lock_init(&channel->inbound_lock);

	channel->controlwq = create_workqueue("hv_vmbus_ctl");
	if (!channel->controlwq) {
	kfree(channel);
	return NULL;
	}

	return channel;
	}

	/*
	* release_hannel - Release the vmbus channel object itself
	*/
	static void release_channel(struct work_struct *work)
	{
	struct vmbus_channel *channel = container_of(work,
	struct vmbus_channel,
	work);

	destroy_workqueue(channel->controlwq);

	kfree(channel);
	}

	/*
	* free_channel - Release the resources used by the vmbus channel object
	*/
	static void free_channel(struct vmbus_channel *channel)
	{

	/*
	* We have to release the channel's workqueue/thread in the vmbus's
	* workqueue/thread context
	* ie we can't destroy ourselves.
	*/
	INIT_WORK(&channel->work, release_channel);
	queue_work(vmbus_connection.work_queue, &channel->work);
	}



	/*
	* vmbus_process_rescind_offer -
	* Rescind the offer by initiating a device removal
	*/
	static void vmbus_process_rescind_offer(struct work_struct *work)
	{
	struct vmbus_channel *channel = container_of(work,
	struct vmbus_channel,
	work);

	vmbus_device_unregister(channel->device_obj);
	}

	void vmbus_free_channels(void)
	{
	struct vmbus_channel *channel;

	list_for_each_entry(channel, &vmbus_connection.chn_list, listentry) {
	vmbus_device_unregister(channel->device_obj);
	kfree(channel->device_obj);
	free_channel(channel);
	}
	}

	/*
	* vmbus_process_offer - Process the offer by creating a channel/device
	* associated with this offer
	*/
	static void vmbus_process_offer(struct work_struct *work)
	{
	struct vmbus_channel *newchannel = container_of(work,
	struct vmbus_channel,
	work);
	struct vmbus_channel *channel;
	bool fnew = true;
	int ret;
	unsigned long flags;

	/* The next possible work is rescind handling */
	INIT_WORK(&newchannel->work, vmbus_process_rescind_offer);

	/* Make sure this is a new offer */
	spin_lock_irqsave(&vmbus_connection.channel_lock, flags);

	list_for_each_entry(channel, &vmbus_connection.chn_list, listentry) {
	if (!uuid_le_cmp(channel->offermsg.offer.if_type,
	newchannel->offermsg.offer.if_type) &&
	!uuid_le_cmp(channel->offermsg.offer.if_instance,
	newchannel->offermsg.offer.if_instance)) {
	fnew = false;
	break;
	}
	}

	if (fnew)
	list_add_tail(&newchannel->listentry,
	&vmbus_connection.chn_list);

	spin_unlock_irqrestore(&vmbus_connection.channel_lock, flags);

	if (!fnew) {
	free_channel(newchannel);
	return;
	}

	/*
	* Start the process of binding this offer to the driver
	* We need to set the DeviceObject field before calling
	* vmbus_child_dev_add()
	*/
	newchannel->device_obj = vmbus_device_create(
	&newchannel->offermsg.offer.if_type,
	&newchannel->offermsg.offer.if_instance,
	newchannel);

	/*
	* Add the new device to the bus. This will kick off device-driver
	* binding which eventually invokes the device driver's AddDevice()
	* method.
	*/
	ret = vmbus_device_register(newchannel->device_obj);
	if (ret != 0) {
	pr_err("unable to add child device object (relid %d)\n",
	newchannel->offermsg.child_relid);

	spin_lock_irqsave(&vmbus_connection.channel_lock, flags);
	list_del(&newchannel->listentry);
	spin_unlock_irqrestore(&vmbus_connection.channel_lock, flags);
	kfree(newchannel->device_obj);

	free_channel(newchannel);
	} else {
	/*
	* This state is used to indicate a successful open
	* so that when we do close the channel normally, we
	* can cleanup properly
	*/
	newchannel->state = CHANNEL_OPEN_STATE;
	}
	}

	/*
	* vmbus_onoffer - Handler for channel offers from vmbus in parent partition.
	*
	*/
	static void vmbus_onoffer(struct vmbus_channel_message_header *hdr)
	{
	struct vmbus_channel_offer_channel *offer;
	struct vmbus_channel *newchannel;
	uuid_le *guidtype;
	uuid_le *guidinstance;

	offer = (struct vmbus_channel_offer_channel *)hdr;

	guidtype = &offer->offer.if_type;
	guidinstance = &offer->offer.if_instance;

	/* Allocate the channel object and save this offer. */
	newchannel = alloc_channel();
	if (!newchannel) {
	pr_err("Unable to allocate channel object\n");
	return;
	}

	memcpy(&newchannel->offermsg, offer,
	sizeof(struct vmbus_channel_offer_channel));
	newchannel->monitor_grp = (u8)offer->monitorid / 32;
	newchannel->monitor_bit = (u8)offer->monitorid % 32;

	INIT_WORK(&newchannel->work, vmbus_process_offer);
	queue_work(newchannel->controlwq, &newchannel->work);
	}

	/*
	* vmbus_onoffer_rescind - Rescind offer handler.
	*
	* We queue a work item to process this offer synchronously
	*/
	static void vmbus_onoffer_rescind(struct vmbus_channel_message_header *hdr)
	{
	struct vmbus_channel_rescind_offer *rescind;
	struct vmbus_channel *channel;

	rescind = (struct vmbus_channel_rescind_offer *)hdr;
	channel = relid2channel(rescind->child_relid);

	if (channel == NULL)
	/* Just return here, no channel found */
	return;

	/* work is initialized for vmbus_process_rescind_offer() from
	* vmbus_process_offer() where the channel got created */
	queue_work(channel->controlwq, &channel->work);
	}

	/*
	* vmbus_onoffers_delivered -
	* This is invoked when all offers have been delivered.
	*
	* Nothing to do here.
	*/
	static void vmbus_onoffers_delivered(
	struct vmbus_channel_message_header *hdr)
	{
	}

	/*
	* vmbus_onopen_result - Open result handler.
	*
	* This is invoked when we received a response to our channel open request.
	* Find the matching request, copy the response and signal the requesting
	* thread.
	*/
	static void vmbus_onopen_result(struct vmbus_channel_message_header *hdr)
	{
	struct vmbus_channel_open_result *result;
	struct vmbus_channel_msginfo *msginfo;
	struct vmbus_channel_message_header *requestheader;
	struct vmbus_channel_open_channel *openmsg;
	unsigned long flags;

	result = (struct vmbus_channel_open_result *)hdr;

	/*
	* Find the open msg, copy the result and signal/unblock the wait event
	*/
	spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);

	list_for_each_entry(msginfo, &vmbus_connection.chn_msg_list,
	msglistentry) {
	requestheader =
	(struct vmbus_channel_message_header *)msginfo->msg;

	if (requestheader->msgtype == CHANNELMSG_OPENCHANNEL) {
	openmsg =
	(struct vmbus_channel_open_channel *)msginfo->msg;
	if (openmsg->child_relid == result->child_relid &&
	openmsg->openid == result->openid) {
	memcpy(&msginfo->response.open_result,
	result,
	sizeof(
	struct vmbus_channel_open_result));
	complete(&msginfo->waitevent);
	break;
	}
	}
	}
	spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
	}

	/*
	* vmbus_ongpadl_created - GPADL created handler.
	*
	* This is invoked when we received a response to our gpadl create request.
	* Find the matching request, copy the response and signal the requesting
	* thread.
	*/
	static void vmbus_ongpadl_created(struct vmbus_channel_message_header *hdr)
	{
	struct vmbus_channel_gpadl_created *gpadlcreated;
	struct vmbus_channel_msginfo *msginfo;
	struct vmbus_channel_message_header *requestheader;
	struct vmbus_channel_gpadl_header *gpadlheader;
	unsigned long flags;

	gpadlcreated = (struct vmbus_channel_gpadl_created *)hdr;

	/*
	* Find the establish msg, copy the result and signal/unblock the wait
	* event
	*/
	spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);

	list_for_each_entry(msginfo, &vmbus_connection.chn_msg_list,
	msglistentry) {
	requestheader =
	(struct vmbus_channel_message_header *)msginfo->msg;

	if (requestheader->msgtype == CHANNELMSG_GPADL_HEADER) {
	gpadlheader =
	(struct vmbus_channel_gpadl_header *)requestheader;

	if ((gpadlcreated->child_relid ==
	gpadlheader->child_relid) &&
	(gpadlcreated->gpadl == gpadlheader->gpadl)) {
	memcpy(&msginfo->response.gpadl_created,
	gpadlcreated,
	sizeof(
	struct vmbus_channel_gpadl_created));
	complete(&msginfo->waitevent);
	break;
	}
	}
	}
	spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
	}

	/*
	* vmbus_ongpadl_torndown - GPADL torndown handler.
	*
	* This is invoked when we received a response to our gpadl teardown request.
	* Find the matching request, copy the response and signal the requesting
	* thread.
	*/
	static void vmbus_ongpadl_torndown(
	struct vmbus_channel_message_header *hdr)
	{
	struct vmbus_channel_gpadl_torndown *gpadl_torndown;
	struct vmbus_channel_msginfo *msginfo;
	struct vmbus_channel_message_header *requestheader;
	struct vmbus_channel_gpadl_teardown *gpadl_teardown;
	unsigned long flags;

	gpadl_torndown = (struct vmbus_channel_gpadl_torndown *)hdr;

	/*
	* Find the open msg, copy the result and signal/unblock the wait event
	*/
	spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);

	list_for_each_entry(msginfo, &vmbus_connection.chn_msg_list,
	msglistentry) {
	requestheader =
	(struct vmbus_channel_message_header *)msginfo->msg;

	if (requestheader->msgtype == CHANNELMSG_GPADL_TEARDOWN) {
	gpadl_teardown =
	(struct vmbus_channel_gpadl_teardown *)requestheader;

	if (gpadl_torndown->gpadl == gpadl_teardown->gpadl) {
	memcpy(&msginfo->response.gpadl_torndown,
	gpadl_torndown,
	sizeof(
	struct vmbus_channel_gpadl_torndown));
	complete(&msginfo->waitevent);
	break;
	}
	}
	}
	spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
	}

	/*
	* vmbus_onversion_response - Version response handler
	*
	* This is invoked when we received a response to our initiate contact request.
	* Find the matching request, copy the response and signal the requesting
	* thread.
	*/
	static void vmbus_onversion_response(
	struct vmbus_channel_message_header *hdr)
	{
	struct vmbus_channel_msginfo *msginfo;
	struct vmbus_channel_message_header *requestheader;
	struct vmbus_channel_initiate_contact *initiate;
	struct vmbus_channel_version_response *version_response;
	unsigned long flags;

	version_response = (struct vmbus_channel_version_response *)hdr;
	spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);

	list_for_each_entry(msginfo, &vmbus_connection.chn_msg_list,
	msglistentry) {
	requestheader =
	(struct vmbus_channel_message_header *)msginfo->msg;

	if (requestheader->msgtype ==
	CHANNELMSG_INITIATE_CONTACT) {
	initiate =
	(struct vmbus_channel_initiate_contact *)requestheader;
	memcpy(&msginfo->response.version_response,
	version_response,
	sizeof(struct vmbus_channel_version_response));
	complete(&msginfo->waitevent);
	}
	}
	spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
	}

	/* Channel message dispatch table */
	static struct vmbus_channel_message_table_entry
	channel_message_table[CHANNELMSG_COUNT] = {
	{CHANNELMSG_INVALID, NULL},
	{CHANNELMSG_OFFERCHANNEL, vmbus_onoffer},
	{CHANNELMSG_RESCIND_CHANNELOFFER, vmbus_onoffer_rescind},
	{CHANNELMSG_REQUESTOFFERS, NULL},
	{CHANNELMSG_ALLOFFERS_DELIVERED, vmbus_onoffers_delivered},
	{CHANNELMSG_OPENCHANNEL, NULL},
	{CHANNELMSG_OPENCHANNEL_RESULT, vmbus_onopen_result},
	{CHANNELMSG_CLOSECHANNEL, NULL},
	{CHANNELMSG_GPADL_HEADER, NULL},
	{CHANNELMSG_GPADL_BODY, NULL},
	{CHANNELMSG_GPADL_CREATED, vmbus_ongpadl_created},
	{CHANNELMSG_GPADL_TEARDOWN, NULL},
	{CHANNELMSG_GPADL_TORNDOWN, vmbus_ongpadl_torndown},
	{CHANNELMSG_RELID_RELEASED, NULL},
	{CHANNELMSG_INITIATE_CONTACT, NULL},
	{CHANNELMSG_VERSION_RESPONSE, vmbus_onversion_response},
	{CHANNELMSG_UNLOAD, NULL},
	};

	/*
	* vmbus_onmessage - Handler for channel protocol messages.
	*
	* This is invoked in the vmbus worker thread context.
	*/
	void vmbus_onmessage(void *context)
	{
	struct hv_message *msg = context;
	struct vmbus_channel_message_header *hdr;
	int size;

	hdr = (struct vmbus_channel_message_header *)msg->u.payload;
	size = msg->header.payload_size;

	if (hdr->msgtype >= CHANNELMSG_COUNT) {
	pr_err("Received invalid channel message type %d size %d\n",
	hdr->msgtype, size);
	print_hex_dump_bytes("", DUMP_PREFIX_NONE,
	(unsigned char *)msg->u.payload, size);
	return;
	}

	if (channel_message_table[hdr->msgtype].message_handler)
	channel_message_table[hdr->msgtype].message_handler(hdr);
	else
	pr_err("Unhandled channel message type %d\n", hdr->msgtype);
	}

	/*
	* vmbus_request_offers - Send a request to get all our pending offers.
	*/
	int vmbus_request_offers(void)
	{
	struct vmbus_channel_message_header *msg;
	struct vmbus_channel_msginfo *msginfo;
	int ret, t;

	msginfo = kmalloc(sizeof(*msginfo) +
	sizeof(struct vmbus_channel_message_header),
	GFP_KERNEL);
	if (!msginfo)
	return -ENOMEM;

	init_completion(&msginfo->waitevent);

	msg = (struct vmbus_channel_message_header *)msginfo->msg;

	msg->msgtype = CHANNELMSG_REQUESTOFFERS;


	ret = vmbus_post_msg(msg,
	sizeof(struct vmbus_channel_message_header));
	if (ret != 0) {
	pr_err("Unable to request offers - %d\n", ret);

	goto cleanup;
	}

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



	cleanup:
	kfree(msginfo);

	return ret;
	}

	/* eof */