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

 /*
  * An implementation of file copy service.
  *
  * Copyright (C) 2014, Microsoft, Inc.
  *
  * Author : K. Y. Srinivasan <ksrinivasan@novell.com>
  *
  * This program is free software; you can redistribute it and/or modify it
  * under the terms of the GNU General Public License version 2 as published
  * by the Free Software Foundation.
  *
  * This program is distributed in the hope that it will be useful, but
  * WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
  * NON INFRINGEMENT.  See the GNU General Public License for more
  * details.
  *
  */

 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

 #include <linux/semaphore.h>
 #include <linux/fs.h>
 #include <linux/nls.h>
 #include <linux/workqueue.h>
 #include <linux/cdev.h>
 #include <linux/hyperv.h>
 #include <linux/sched.h>
 #include <linux/uaccess.h>
 #include <linux/miscdevice.h>

 #include "hyperv_vmbus.h"

 #define WIN8_SRV_MAJOR		1
 #define WIN8_SRV_MINOR		1
 #define WIN8_SRV_VERSION	(WIN8_SRV_MAJOR << 16 | WIN8_SRV_MINOR)

 /*
  * Global state maintained for transaction that is being processed.
  * For a class of integration services, including the "file copy service",
  * the specified protocol is a "request/response" protocol which means that
  * there can only be single outstanding transaction from the host at any
  * given point in time. We use this to simplify memory management in this
  * driver - we cache and process only one message at a time.
  *
  * While the request/response protocol is guaranteed by the host, we further
  * ensure this by serializing packet processing in this driver - we do not
  * read additional packets from the VMBUs until the current packet is fully
  * handled.
  *
  * The transaction "active" state is set when we receive a request from the
  * host and we cleanup this state when the transaction is completed - when we
  * respond to the host with our response. When the transaction active state is
  * set, we defer handling incoming packets.
  */

 static struct {
 	bool active; /* transaction status - active or not */
 	int recv_len; /* number of bytes received. */
 	struct hv_fcopy_hdr  *fcopy_msg; /* current message */
 	struct hv_start_fcopy  message; /*  sent to daemon */
 	struct vmbus_channel *recv_channel; /* chn we got the request */
 	u64 recv_req_id; /* request ID. */
 	void *fcopy_context; /* for the channel callback */
 	struct semaphore read_sema;
 } fcopy_transaction;

 static bool opened; /* currently device opened */

 /*
  * Before we can accept copy messages from the host, we need
  * to handshake with the user level daemon. This state tracks
  * if we are in the handshake phase.
  */
 static bool in_hand_shake = true;
 static void fcopy_send_data(void);
 static void fcopy_respond_to_host(int error);
 static void fcopy_work_func(struct work_struct *dummy);
 static DECLARE_DELAYED_WORK(fcopy_work, fcopy_work_func);
 static u8 *recv_buffer;

 static void fcopy_work_func(struct work_struct *dummy)
 {
 	/*
 	 * If the timer fires, the user-mode component has not responded;
 	 * process the pending transaction.
 	 */
 	fcopy_respond_to_host(HV_E_FAIL);
 }

 static int fcopy_handle_handshake(u32 version)
 {
 	switch (version) {
 	case FCOPY_CURRENT_VERSION:
 		break;
 	default:
 		/*
 		 * For now we will fail the registration.
 		 * If and when we have multiple versions to
 		 * deal with, we will be backward compatible.
 		 * We will add this code when needed.
 		 */
 		return -EINVAL;
 	}
 	pr_info("FCP: user-mode registering done. Daemon version: %d\n",
 		version);
 	fcopy_transaction.active = false;
 	if (fcopy_transaction.fcopy_context)
 		hv_fcopy_onchannelcallback(fcopy_transaction.fcopy_context);
 	in_hand_shake = false;
 	return 0;
 }

 static void fcopy_send_data(void)
 {
 	struct hv_start_fcopy *smsg_out = &fcopy_transaction.message;
 	int operation = fcopy_transaction.fcopy_msg->operation;
 	struct hv_start_fcopy *smsg_in;

 	/*
 	 * The  strings sent from the host are encoded in
 	 * in utf16; convert it to utf8 strings.
 	 * The host assures us that the utf16 strings will not exceed
 	 * the max lengths specified. We will however, reserve room
 	 * for the string terminating character - in the utf16s_utf8s()
 	 * function we limit the size of the buffer where the converted
 	 * string is placed to W_MAX_PATH -1 to guarantee
 	 * that the strings can be properly terminated!
 	 */

 	switch (operation) {
 	case START_FILE_COPY:
 		memset(smsg_out, 0, sizeof(struct hv_start_fcopy));
 		smsg_out->hdr.operation = operation;
 		smsg_in = (struct hv_start_fcopy *)fcopy_transaction.fcopy_msg;

 		utf16s_to_utf8s((wchar_t *)smsg_in->file_name, W_MAX_PATH,
 				UTF16_LITTLE_ENDIAN,
 				(__u8 *)smsg_out->file_name, W_MAX_PATH - 1);

 		utf16s_to_utf8s((wchar_t *)smsg_in->path_name, W_MAX_PATH,
 				UTF16_LITTLE_ENDIAN,
 				(__u8 *)smsg_out->path_name, W_MAX_PATH - 1);

 		smsg_out->copy_flags = smsg_in->copy_flags;
 		smsg_out->file_size = smsg_in->file_size;
 		break;

 	default:
 		break;
 	}
 	up(&fcopy_transaction.read_sema);
 	return;
 }

 /*
  * Send a response back to the host.
  */

 static void
 fcopy_respond_to_host(int error)
 {
 	struct icmsg_hdr *icmsghdr;
 	u32 buf_len;
 	struct vmbus_channel *channel;
 	u64 req_id;

 	/*
 	 * Copy the global state for completing the transaction. Note that
 	 * only one transaction can be active at a time. This is guaranteed
 	 * by the file copy protocol implemented by the host. Furthermore,
 	 * the "transaction active" state we maintain ensures that there can
 	 * only be one active transaction at a time.
 	 */

 	buf_len = fcopy_transaction.recv_len;
 	channel = fcopy_transaction.recv_channel;
 	req_id = fcopy_transaction.recv_req_id;

 	fcopy_transaction.active = false;

 	icmsghdr = (struct icmsg_hdr *)
 			&recv_buffer[sizeof(struct vmbuspipe_hdr)];

 	if (channel->onchannel_callback == NULL)
 		/*
 		 * We have raced with util driver being unloaded;
 		 * silently return.
 		 */
 		return;

 	icmsghdr->status = error;
 	icmsghdr->icflags = ICMSGHDRFLAG_TRANSACTION | ICMSGHDRFLAG_RESPONSE;
 	vmbus_sendpacket(channel, recv_buffer, buf_len, req_id,
 				VM_PKT_DATA_INBAND, 0);
 }

 void hv_fcopy_onchannelcallback(void *context)
 {
 	struct vmbus_channel *channel = context;
 	u32 recvlen;
 	u64 requestid;
 	struct hv_fcopy_hdr *fcopy_msg;
 	struct icmsg_hdr *icmsghdr;
 	struct icmsg_negotiate *negop = NULL;
 	int util_fw_version;
 	int fcopy_srv_version;

 	if (fcopy_transaction.active) {
 		/*
 		 * We will defer processing this callback once
 		 * the current transaction is complete.
 		 */
 		fcopy_transaction.fcopy_context = context;
 		return;
 	}

 	vmbus_recvpacket(channel, recv_buffer, PAGE_SIZE * 2, &recvlen,
 			 &requestid);
 	if (recvlen <= 0)
 		return;

 	icmsghdr = (struct icmsg_hdr *)&recv_buffer[
 			sizeof(struct vmbuspipe_hdr)];
 	if (icmsghdr->icmsgtype == ICMSGTYPE_NEGOTIATE) {
 		util_fw_version = UTIL_FW_VERSION;
 		fcopy_srv_version = WIN8_SRV_VERSION;
 		vmbus_prep_negotiate_resp(icmsghdr, negop, recv_buffer,
 				util_fw_version, fcopy_srv_version);
 	} else {
 		fcopy_msg = (struct hv_fcopy_hdr *)&recv_buffer[
 				sizeof(struct vmbuspipe_hdr) +
 				sizeof(struct icmsg_hdr)];

 		/*
 		 * Stash away this global state for completing the
 		 * transaction; note transactions are serialized.
 		 */

 		fcopy_transaction.active = true;
 		fcopy_transaction.recv_len = recvlen;
 		fcopy_transaction.recv_channel = channel;
 		fcopy_transaction.recv_req_id = requestid;
 		fcopy_transaction.fcopy_msg = fcopy_msg;

 		/*
 		 * Send the information to the user-level daemon.
 		 */
 		schedule_delayed_work(&fcopy_work, 5*HZ);
 		fcopy_send_data();
 		return;
 	}
 	icmsghdr->icflags = ICMSGHDRFLAG_TRANSACTION | ICMSGHDRFLAG_RESPONSE;
 	vmbus_sendpacket(channel, recv_buffer, recvlen, requestid,
 			VM_PKT_DATA_INBAND, 0);
 }

 /*
  * Create a char device that can support read/write for passing
  * the payload.
  */

 static ssize_t fcopy_read(struct file *file, char __user *buf,
 		size_t count, loff_t *ppos)
 {
 	void *src;
 	size_t copy_size;
 	int operation;

 	/*
 	 * Wait until there is something to be read.
 	 */
 	if (down_interruptible(&fcopy_transaction.read_sema))
 		return -EINTR;

 	/*
 	 * The channel may be rescinded and in this case, we will wakeup the
 	 * the thread blocked on the semaphore and we will use the opened
 	 * state to correctly handle this case.
 	 */
 	if (!opened)
 		return -ENODEV;

 	operation = fcopy_transaction.fcopy_msg->operation;

 	if (operation == START_FILE_COPY) {
 		src = &fcopy_transaction.message;
 		copy_size = sizeof(struct hv_start_fcopy);
 		if (count < copy_size)
 			return 0;
 	} else {
 		src = fcopy_transaction.fcopy_msg;
 		copy_size = sizeof(struct hv_do_fcopy);
 		if (count < copy_size)
 			return 0;
 	}
 	if (copy_to_user(buf, src, copy_size))
 		return -EFAULT;

 	return copy_size;
 }

 static ssize_t fcopy_write(struct file *file, const char __user *buf,
 			size_t count, loff_t *ppos)
 {
 	int response = 0;

 	if (count != sizeof(int))
 		return -EINVAL;

 	if (copy_from_user(&response, buf, sizeof(int)))
 		return -EFAULT;

 	if (in_hand_shake) {
 		if (fcopy_handle_handshake(response))
 			return -EINVAL;
 		return sizeof(int);
 	}

 	/*
 	 * Complete the transaction by forwarding the result
 	 * to the host. But first, cancel the timeout.
 	 */
 	if (cancel_delayed_work_sync(&fcopy_work))
 		fcopy_respond_to_host(response);

 	return sizeof(int);
 }

 static int fcopy_open(struct inode *inode, struct file *f)
 {
 	/*
 	 * The user level daemon that will open this device is
 	 * really an extension of this driver. We can have only
 	 * active open at a time.
 	 */
 	if (opened)
 		return -EBUSY;

 	/*
 	 * The daemon is alive; setup the state.
 	 */
 	opened = true;
 	return 0;
 }

 static int fcopy_release(struct inode *inode, struct file *f)
 {
 	/*
 	 * The daemon has exited; reset the state.
 	 */
 	in_hand_shake = true;
 	opened = false;
 	return 0;
 }


 static const struct file_operations fcopy_fops = {
 	.read           = fcopy_read,
 	.write          = fcopy_write,
 	.release	= fcopy_release,
 	.open		= fcopy_open,
 };

 static struct miscdevice fcopy_misc = {
 	.minor          = MISC_DYNAMIC_MINOR,
 	.name           = "vmbus/hv_fcopy",
 	.fops           = &fcopy_fops,
 };

 static int fcopy_dev_init(void)
 {
 	return misc_register(&fcopy_misc);
 }

 static void fcopy_dev_deinit(void)
 {

 	/*
 	 * The device is going away - perhaps because the
 	 * host has rescinded the channel. Setup state so that
 	 * user level daemon can gracefully exit if it is blocked
 	 * on the read semaphore.
 	 */
 	opened = false;
 	/*
 	 * Signal the semaphore as the device is
 	 * going away.
 	 */
 	up(&fcopy_transaction.read_sema);
 	misc_deregister(&fcopy_misc);
 }

 int hv_fcopy_init(struct hv_util_service *srv)
 {
 	recv_buffer = srv->recv_buffer;

 	/*
 	 * When this driver loads, the user level daemon that
 	 * processes the host requests may not yet be running.
 	 * Defer processing channel callbacks until the daemon
 	 * has registered.
 	 */
 	fcopy_transaction.active = true;
 	sema_init(&fcopy_transaction.read_sema, 0);

 	return fcopy_dev_init();
 }

 void hv_fcopy_deinit(void)
 {
 	cancel_delayed_work_sync(&fcopy_work);
 	fcopy_dev_deinit();
 }
	/*
	* An implementation of file copy service.
	*
	* Copyright (C) 2014, Microsoft, Inc.
	*
	* Author : K. Y. Srinivasan <ksrinivasan@novell.com>
	*
	* This program is free software; you can redistribute it and/or modify it
	* under the terms of the GNU General Public License version 2 as published
	* by the Free Software Foundation.
	*
	* This program is distributed in the hope that it will be useful, but
	* WITHOUT ANY WARRANTY; without even the implied warranty of
	* MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
	* NON INFRINGEMENT. See the GNU General Public License for more
	* details.
	*
	*/

	#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

	#include <linux/semaphore.h>
	#include <linux/fs.h>
	#include <linux/nls.h>
	#include <linux/workqueue.h>
	#include <linux/cdev.h>
	#include <linux/hyperv.h>
	#include <linux/sched.h>
	#include <linux/uaccess.h>
	#include <linux/miscdevice.h>

	#include "hyperv_vmbus.h"

	#define WIN8_SRV_MAJOR 1
	#define WIN8_SRV_MINOR 1
	#define WIN8_SRV_VERSION (WIN8_SRV_MAJOR << 16 \| WIN8_SRV_MINOR)

	/*
	* Global state maintained for transaction that is being processed.
	* For a class of integration services, including the "file copy service",
	* the specified protocol is a "request/response" protocol which means that
	* there can only be single outstanding transaction from the host at any
	* given point in time. We use this to simplify memory management in this
	* driver - we cache and process only one message at a time.
	*
	* While the request/response protocol is guaranteed by the host, we further
	* ensure this by serializing packet processing in this driver - we do not
	* read additional packets from the VMBUs until the current packet is fully
	* handled.
	*
	* The transaction "active" state is set when we receive a request from the
	* host and we cleanup this state when the transaction is completed - when we
	* respond to the host with our response. When the transaction active state is
	* set, we defer handling incoming packets.
	*/

	static struct {
	bool active; /* transaction status - active or not */
	int recv_len; /* number of bytes received. */
	struct hv_fcopy_hdr fcopy_msg; / current message */
	struct hv_start_fcopy message; /* sent to daemon */
	struct vmbus_channel recv_channel; / chn we got the request */
	u64 recv_req_id; /* request ID. */
	void fcopy_context; / for the channel callback */
	struct semaphore read_sema;
	} fcopy_transaction;

	static bool opened; /* currently device opened */

	/*
	* Before we can accept copy messages from the host, we need
	* to handshake with the user level daemon. This state tracks
	* if we are in the handshake phase.
	*/
	static bool in_hand_shake = true;
	static void fcopy_send_data(void);
	static void fcopy_respond_to_host(int error);
	static void fcopy_work_func(struct work_struct *dummy);
	static DECLARE_DELAYED_WORK(fcopy_work, fcopy_work_func);
	static u8 *recv_buffer;

	static void fcopy_work_func(struct work_struct *dummy)
	{
	/*
	* If the timer fires, the user-mode component has not responded;
	* process the pending transaction.
	*/
	fcopy_respond_to_host(HV_E_FAIL);
	}

	static int fcopy_handle_handshake(u32 version)
	{
	switch (version) {
	case FCOPY_CURRENT_VERSION:
	break;
	default:
	/*
	* For now we will fail the registration.
	* If and when we have multiple versions to
	* deal with, we will be backward compatible.
	* We will add this code when needed.
	*/
	return -EINVAL;
	}
	pr_info("FCP: user-mode registering done. Daemon version: %d\n",
	version);
	fcopy_transaction.active = false;
	if (fcopy_transaction.fcopy_context)
	hv_fcopy_onchannelcallback(fcopy_transaction.fcopy_context);
	in_hand_shake = false;
	return 0;
	}

	static void fcopy_send_data(void)
	{
	struct hv_start_fcopy *smsg_out = &fcopy_transaction.message;
	int operation = fcopy_transaction.fcopy_msg->operation;
	struct hv_start_fcopy *smsg_in;

	/*
	* The strings sent from the host are encoded in
	* in utf16; convert it to utf8 strings.
	* The host assures us that the utf16 strings will not exceed
	* the max lengths specified. We will however, reserve room
	* for the string terminating character - in the utf16s_utf8s()
	* function we limit the size of the buffer where the converted
	* string is placed to W_MAX_PATH -1 to guarantee
	* that the strings can be properly terminated!
	*/

	switch (operation) {
	case START_FILE_COPY:
	memset(smsg_out, 0, sizeof(struct hv_start_fcopy));
	smsg_out->hdr.operation = operation;
	smsg_in = (struct hv_start_fcopy *)fcopy_transaction.fcopy_msg;

	utf16s_to_utf8s((wchar_t *)smsg_in->file_name, W_MAX_PATH,
	UTF16_LITTLE_ENDIAN,
	(__u8 *)smsg_out->file_name, W_MAX_PATH - 1);

	utf16s_to_utf8s((wchar_t *)smsg_in->path_name, W_MAX_PATH,
	UTF16_LITTLE_ENDIAN,
	(__u8 *)smsg_out->path_name, W_MAX_PATH - 1);

	smsg_out->copy_flags = smsg_in->copy_flags;
	smsg_out->file_size = smsg_in->file_size;
	break;

	default:
	break;
	}
	up(&fcopy_transaction.read_sema);
	return;
	}

	/*
	* Send a response back to the host.
	*/

	static void
	fcopy_respond_to_host(int error)
	{
	struct icmsg_hdr *icmsghdr;
	u32 buf_len;
	struct vmbus_channel *channel;
	u64 req_id;

	/*
	* Copy the global state for completing the transaction. Note that
	* only one transaction can be active at a time. This is guaranteed
	* by the file copy protocol implemented by the host. Furthermore,
	* the "transaction active" state we maintain ensures that there can
	* only be one active transaction at a time.
	*/

	buf_len = fcopy_transaction.recv_len;
	channel = fcopy_transaction.recv_channel;
	req_id = fcopy_transaction.recv_req_id;

	fcopy_transaction.active = false;

	icmsghdr = (struct icmsg_hdr *)
	&recv_buffer[sizeof(struct vmbuspipe_hdr)];

	if (channel->onchannel_callback == NULL)
	/*
	* We have raced with util driver being unloaded;
	* silently return.
	*/
	return;

	icmsghdr->status = error;
	icmsghdr->icflags = ICMSGHDRFLAG_TRANSACTION \| ICMSGHDRFLAG_RESPONSE;
	vmbus_sendpacket(channel, recv_buffer, buf_len, req_id,
	VM_PKT_DATA_INBAND, 0);
	}

	void hv_fcopy_onchannelcallback(void *context)
	{
	struct vmbus_channel *channel = context;
	u32 recvlen;
	u64 requestid;
	struct hv_fcopy_hdr *fcopy_msg;
	struct icmsg_hdr *icmsghdr;
	struct icmsg_negotiate *negop = NULL;
	int util_fw_version;
	int fcopy_srv_version;

	if (fcopy_transaction.active) {
	/*
	* We will defer processing this callback once
	* the current transaction is complete.
	*/
	fcopy_transaction.fcopy_context = context;
	return;
	}

	vmbus_recvpacket(channel, recv_buffer, PAGE_SIZE * 2, &recvlen,
	&requestid);
	if (recvlen <= 0)
	return;

	icmsghdr = (struct icmsg_hdr *)&recv_buffer[
	sizeof(struct vmbuspipe_hdr)];
	if (icmsghdr->icmsgtype == ICMSGTYPE_NEGOTIATE) {
	util_fw_version = UTIL_FW_VERSION;
	fcopy_srv_version = WIN8_SRV_VERSION;
	vmbus_prep_negotiate_resp(icmsghdr, negop, recv_buffer,
	util_fw_version, fcopy_srv_version);
	} else {
	fcopy_msg = (struct hv_fcopy_hdr *)&recv_buffer[
	sizeof(struct vmbuspipe_hdr) +
	sizeof(struct icmsg_hdr)];

	/*
	* Stash away this global state for completing the
	* transaction; note transactions are serialized.
	*/

	fcopy_transaction.active = true;
	fcopy_transaction.recv_len = recvlen;
	fcopy_transaction.recv_channel = channel;
	fcopy_transaction.recv_req_id = requestid;
	fcopy_transaction.fcopy_msg = fcopy_msg;

	/*
	* Send the information to the user-level daemon.
	*/
	schedule_delayed_work(&fcopy_work, 5*HZ);
	fcopy_send_data();
	return;
	}
	icmsghdr->icflags = ICMSGHDRFLAG_TRANSACTION \| ICMSGHDRFLAG_RESPONSE;
	vmbus_sendpacket(channel, recv_buffer, recvlen, requestid,
	VM_PKT_DATA_INBAND, 0);
	}

	/*
	* Create a char device that can support read/write for passing
	* the payload.
	*/

	static ssize_t fcopy_read(struct file file, char __user buf,
	size_t count, loff_t *ppos)
	{
	void *src;
	size_t copy_size;
	int operation;

	/*
	* Wait until there is something to be read.
	*/
	if (down_interruptible(&fcopy_transaction.read_sema))
	return -EINTR;

	/*
	* The channel may be rescinded and in this case, we will wakeup the
	* the thread blocked on the semaphore and we will use the opened
	* state to correctly handle this case.
	*/
	if (!opened)
	return -ENODEV;

	operation = fcopy_transaction.fcopy_msg->operation;

	if (operation == START_FILE_COPY) {
	src = &fcopy_transaction.message;
	copy_size = sizeof(struct hv_start_fcopy);
	if (count < copy_size)
	return 0;
	} else {
	src = fcopy_transaction.fcopy_msg;
	copy_size = sizeof(struct hv_do_fcopy);
	if (count < copy_size)
	return 0;
	}
	if (copy_to_user(buf, src, copy_size))
	return -EFAULT;

	return copy_size;
	}

	static ssize_t fcopy_write(struct file file, const char __user buf,
	size_t count, loff_t *ppos)
	{
	int response = 0;

	if (count != sizeof(int))
	return -EINVAL;

	if (copy_from_user(&response, buf, sizeof(int)))
	return -EFAULT;

	if (in_hand_shake) {
	if (fcopy_handle_handshake(response))
	return -EINVAL;
	return sizeof(int);
	}

	/*
	* Complete the transaction by forwarding the result
	* to the host. But first, cancel the timeout.
	*/
	if (cancel_delayed_work_sync(&fcopy_work))
	fcopy_respond_to_host(response);

	return sizeof(int);
	}

	static int fcopy_open(struct inode inode, struct file f)
	{
	/*
	* The user level daemon that will open this device is
	* really an extension of this driver. We can have only
	* active open at a time.
	*/
	if (opened)
	return -EBUSY;

	/*
	* The daemon is alive; setup the state.
	*/
	opened = true;
	return 0;
	}

	static int fcopy_release(struct inode inode, struct file f)
	{
	/*
	* The daemon has exited; reset the state.
	*/
	in_hand_shake = true;
	opened = false;
	return 0;
	}


	static const struct file_operations fcopy_fops = {
	.read = fcopy_read,
	.write = fcopy_write,
	.release = fcopy_release,
	.open = fcopy_open,
	};

	static struct miscdevice fcopy_misc = {
	.minor = MISC_DYNAMIC_MINOR,
	.name = "vmbus/hv_fcopy",
	.fops = &fcopy_fops,
	};

	static int fcopy_dev_init(void)
	{
	return misc_register(&fcopy_misc);
	}

	static void fcopy_dev_deinit(void)
	{

	/*
	* The device is going away - perhaps because the
	* host has rescinded the channel. Setup state so that
	* user level daemon can gracefully exit if it is blocked
	* on the read semaphore.
	*/
	opened = false;
	/*
	* Signal the semaphore as the device is
	* going away.
	*/
	up(&fcopy_transaction.read_sema);
	misc_deregister(&fcopy_misc);
	}

	int hv_fcopy_init(struct hv_util_service *srv)
	{
	recv_buffer = srv->recv_buffer;

	/*
	* When this driver loads, the user level daemon that
	* processes the host requests may not yet be running.
	* Defer processing channel callbacks until the daemon
	* has registered.
	*/
	fcopy_transaction.active = true;
	sema_init(&fcopy_transaction.read_sema, 0);

	return fcopy_dev_init();
	}

	void hv_fcopy_deinit(void)
	{
	cancel_delayed_work_sync(&fcopy_work);
	fcopy_dev_deinit();
	}