drivers/usb/usbip/stub_dev.c - third_party/linux - Git at Google

 /*
  * Copyright (C) 2003-2008 Takahiro Hirofuchi
  *
  * This is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
  * the Free Software Foundation; either version 2 of the License, or
  * (at your option) any later version.
  *
  * This 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.  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.
  */

 #include <linux/device.h>
 #include <linux/file.h>
 #include <linux/kthread.h>
 #include <linux/module.h>

 #include "usbip_common.h"
 #include "stub.h"

 /*
  * usbip_status shows the status of usbip-host as long as this driver is bound
  * to the target device.
  */
 static ssize_t usbip_status_show(struct device *dev,
 				 struct device_attribute *attr, char *buf)
 {
 	struct stub_device *sdev = dev_get_drvdata(dev);
 	int status;

 	if (!sdev) {
 		dev_err(dev, "sdev is null\n");
 		return -ENODEV;
 	}

 	spin_lock_irq(&sdev->ud.lock);
 	status = sdev->ud.status;
 	spin_unlock_irq(&sdev->ud.lock);

 	return snprintf(buf, PAGE_SIZE, "%d\n", status);
 }
 static DEVICE_ATTR_RO(usbip_status);

 /*
  * usbip_sockfd gets a socket descriptor of an established TCP connection that
  * is used to transfer usbip requests by kernel threads. -1 is a magic number
  * by which usbip connection is finished.
  */
 static ssize_t store_sockfd(struct device *dev, struct device_attribute *attr,
 			    const char *buf, size_t count)
 {
 	struct stub_device *sdev = dev_get_drvdata(dev);
 	int sockfd = 0;
 	struct socket *socket;
 	int rv;

 	if (!sdev) {
 		dev_err(dev, "sdev is null\n");
 		return -ENODEV;
 	}

 	rv = sscanf(buf, "%d", &sockfd);
 	if (rv != 1)
 		return -EINVAL;

 	if (sockfd != -1) {
 		int err;

 		dev_info(dev, "stub up\n");

 		spin_lock_irq(&sdev->ud.lock);

 		if (sdev->ud.status != SDEV_ST_AVAILABLE) {
 			dev_err(dev, "not ready\n");
 			goto err;
 		}

 		socket = sockfd_lookup(sockfd, &err);
 		if (!socket)
 			goto err;

 		sdev->ud.tcp_socket = socket;
 		sdev->ud.sockfd = sockfd;

 		spin_unlock_irq(&sdev->ud.lock);

 		sdev->ud.tcp_rx = kthread_get_run(stub_rx_loop, &sdev->ud,
 						  "stub_rx");
 		sdev->ud.tcp_tx = kthread_get_run(stub_tx_loop, &sdev->ud,
 						  "stub_tx");

 		spin_lock_irq(&sdev->ud.lock);
 		sdev->ud.status = SDEV_ST_USED;
 		spin_unlock_irq(&sdev->ud.lock);

 	} else {
 		dev_info(dev, "stub down\n");

 		spin_lock_irq(&sdev->ud.lock);
 		if (sdev->ud.status != SDEV_ST_USED)
 			goto err;

 		spin_unlock_irq(&sdev->ud.lock);

 		usbip_event_add(&sdev->ud, SDEV_EVENT_DOWN);
 	}

 	return count;

 err:
 	spin_unlock_irq(&sdev->ud.lock);
 	return -EINVAL;
 }
 static DEVICE_ATTR(usbip_sockfd, S_IWUSR, NULL, store_sockfd);

 static int stub_add_files(struct device *dev)
 {
 	int err = 0;

 	err = device_create_file(dev, &dev_attr_usbip_status);
 	if (err)
 		goto err_status;

 	err = device_create_file(dev, &dev_attr_usbip_sockfd);
 	if (err)
 		goto err_sockfd;

 	err = device_create_file(dev, &dev_attr_usbip_debug);
 	if (err)
 		goto err_debug;

 	return 0;

 err_debug:
 	device_remove_file(dev, &dev_attr_usbip_sockfd);
 err_sockfd:
 	device_remove_file(dev, &dev_attr_usbip_status);
 err_status:
 	return err;
 }

 static void stub_remove_files(struct device *dev)
 {
 	device_remove_file(dev, &dev_attr_usbip_status);
 	device_remove_file(dev, &dev_attr_usbip_sockfd);
 	device_remove_file(dev, &dev_attr_usbip_debug);
 }

 static void stub_shutdown_connection(struct usbip_device *ud)
 {
 	struct stub_device *sdev = container_of(ud, struct stub_device, ud);

 	/*
 	 * When removing an exported device, kernel panic sometimes occurred
 	 * and then EIP was sk_wait_data of stub_rx thread. Is this because
 	 * sk_wait_data returned though stub_rx thread was already finished by
 	 * step 1?
 	 */
 	if (ud->tcp_socket) {
 		dev_dbg(&sdev->udev->dev, "shutdown sockfd %d\n", ud->sockfd);
 		kernel_sock_shutdown(ud->tcp_socket, SHUT_RDWR);
 	}

 	/* 1. stop threads */
 	if (ud->tcp_rx) {
 		kthread_stop_put(ud->tcp_rx);
 		ud->tcp_rx = NULL;
 	}
 	if (ud->tcp_tx) {
 		kthread_stop_put(ud->tcp_tx);
 		ud->tcp_tx = NULL;
 	}

 	/*
 	 * 2. close the socket
 	 *
 	 * tcp_socket is freed after threads are killed so that usbip_xmit does
 	 * not touch NULL socket.
 	 */
 	if (ud->tcp_socket) {
 		sockfd_put(ud->tcp_socket);
 		ud->tcp_socket = NULL;
 		ud->sockfd = -1;
 	}

 	/* 3. free used data */
 	stub_device_cleanup_urbs(sdev);

 	/* 4. free stub_unlink */
 	{
 		unsigned long flags;
 		struct stub_unlink *unlink, *tmp;

 		spin_lock_irqsave(&sdev->priv_lock, flags);
 		list_for_each_entry_safe(unlink, tmp, &sdev->unlink_tx, list) {
 			list_del(&unlink->list);
 			kfree(unlink);
 		}
 		list_for_each_entry_safe(unlink, tmp, &sdev->unlink_free,
 					 list) {
 			list_del(&unlink->list);
 			kfree(unlink);
 		}
 		spin_unlock_irqrestore(&sdev->priv_lock, flags);
 	}
 }

 static void stub_device_reset(struct usbip_device *ud)
 {
 	struct stub_device *sdev = container_of(ud, struct stub_device, ud);
 	struct usb_device *udev = sdev->udev;
 	int ret;

 	dev_dbg(&udev->dev, "device reset");

 	ret = usb_lock_device_for_reset(udev, sdev->interface);
 	if (ret < 0) {
 		dev_err(&udev->dev, "lock for reset\n");
 		spin_lock_irq(&ud->lock);
 		ud->status = SDEV_ST_ERROR;
 		spin_unlock_irq(&ud->lock);
 		return;
 	}

 	/* try to reset the device */
 	ret = usb_reset_device(udev);
 	usb_unlock_device(udev);

 	spin_lock_irq(&ud->lock);
 	if (ret) {
 		dev_err(&udev->dev, "device reset\n");
 		ud->status = SDEV_ST_ERROR;
 	} else {
 		dev_info(&udev->dev, "device reset\n");
 		ud->status = SDEV_ST_AVAILABLE;
 	}
 	spin_unlock_irq(&ud->lock);
 }

 static void stub_device_unusable(struct usbip_device *ud)
 {
 	spin_lock_irq(&ud->lock);
 	ud->status = SDEV_ST_ERROR;
 	spin_unlock_irq(&ud->lock);
 }

 /**
  * stub_device_alloc - allocate a new stub_device struct
  * @interface: usb_interface of a new device
  *
  * Allocates and initializes a new stub_device struct.
  */
 static struct stub_device *stub_device_alloc(struct usb_device *udev)
 {
 	struct stub_device *sdev;
 	int busnum = udev->bus->busnum;
 	int devnum = udev->devnum;

 	dev_dbg(&udev->dev, "allocating stub device");

 	/* yes, it's a new device */
 	sdev = kzalloc(sizeof(struct stub_device), GFP_KERNEL);
 	if (!sdev)
 		return NULL;

 	sdev->udev = usb_get_dev(udev);

 	/*
 	 * devid is defined with devnum when this driver is first allocated.
 	 * devnum may change later if a device is reset. However, devid never
 	 * changes during a usbip connection.
 	 */
 	sdev->devid		= (busnum << 16) | devnum;
 	sdev->ud.side		= USBIP_STUB;
 	sdev->ud.status		= SDEV_ST_AVAILABLE;
 	spin_lock_init(&sdev->ud.lock);
 	sdev->ud.tcp_socket	= NULL;
 	sdev->ud.sockfd		= -1;

 	INIT_LIST_HEAD(&sdev->priv_init);
 	INIT_LIST_HEAD(&sdev->priv_tx);
 	INIT_LIST_HEAD(&sdev->priv_free);
 	INIT_LIST_HEAD(&sdev->unlink_free);
 	INIT_LIST_HEAD(&sdev->unlink_tx);
 	spin_lock_init(&sdev->priv_lock);

 	init_waitqueue_head(&sdev->tx_waitq);

 	sdev->ud.eh_ops.shutdown = stub_shutdown_connection;
 	sdev->ud.eh_ops.reset    = stub_device_reset;
 	sdev->ud.eh_ops.unusable = stub_device_unusable;

 	usbip_start_eh(&sdev->ud);

 	dev_dbg(&udev->dev, "register new device\n");

 	return sdev;
 }

 static void stub_device_free(struct stub_device *sdev)
 {
 	kfree(sdev);
 }

 static int stub_probe(struct usb_device *udev)
 {
 	struct stub_device *sdev = NULL;
 	const char *udev_busid = dev_name(&udev->dev);
 	struct bus_id_priv *busid_priv;
 	int rc = 0;

 	dev_dbg(&udev->dev, "Enter probe\n");

 	/* check we should claim or not by busid_table */
 	busid_priv = get_busid_priv(udev_busid);
 	if (!busid_priv || (busid_priv->status == STUB_BUSID_REMOV) ||
 	    (busid_priv->status == STUB_BUSID_OTHER)) {
 		dev_info(&udev->dev,
 			"%s is not in match_busid table... skip!\n",
 			udev_busid);

 		/*
 		 * Return value should be ENODEV or ENOXIO to continue trying
 		 * other matched drivers by the driver core.
 		 * See driver_probe_device() in driver/base/dd.c
 		 */
 		rc = -ENODEV;
 		goto call_put_busid_priv;
 	}

 	if (udev->descriptor.bDeviceClass == USB_CLASS_HUB) {
 		dev_dbg(&udev->dev, "%s is a usb hub device... skip!\n",
 			 udev_busid);
 		rc = -ENODEV;
 		goto call_put_busid_priv;
 	}

 	if (!strcmp(udev->bus->bus_name, "vhci_hcd")) {
 		dev_dbg(&udev->dev,
 			"%s is attached on vhci_hcd... skip!\n",
 			udev_busid);

 		rc = -ENODEV;
 		goto call_put_busid_priv;
 	}

 	/* ok, this is my device */
 	sdev = stub_device_alloc(udev);
 	if (!sdev) {
 		rc = -ENOMEM;
 		goto call_put_busid_priv;
 	}

 	dev_info(&udev->dev,
 		"usbip-host: register new device (bus %u dev %u)\n",
 		udev->bus->busnum, udev->devnum);

 	busid_priv->shutdown_busid = 0;

 	/* set private data to usb_device */
 	dev_set_drvdata(&udev->dev, sdev);
 	busid_priv->sdev = sdev;
 	busid_priv->udev = udev;

 	/*
 	 * Claim this hub port.
 	 * It doesn't matter what value we pass as owner
 	 * (struct dev_state) as long as it is unique.
 	 */
 	rc = usb_hub_claim_port(udev->parent, udev->portnum,
 			(struct usb_dev_state *) udev);
 	if (rc) {
 		dev_dbg(&udev->dev, "unable to claim port\n");
 		goto err_port;
 	}

 	rc = stub_add_files(&udev->dev);
 	if (rc) {
 		dev_err(&udev->dev, "stub_add_files for %s\n", udev_busid);
 		goto err_files;
 	}
 	busid_priv->status = STUB_BUSID_ALLOC;

 	rc = 0;
 	goto call_put_busid_priv;

 err_files:
 	usb_hub_release_port(udev->parent, udev->portnum,
 			     (struct usb_dev_state *) udev);
 err_port:
 	dev_set_drvdata(&udev->dev, NULL);
 	usb_put_dev(udev);
 	kthread_stop_put(sdev->ud.eh);

 	busid_priv->sdev = NULL;
 	stub_device_free(sdev);

 call_put_busid_priv:
 	put_busid_priv(busid_priv);
 	return rc;
 }

 static void shutdown_busid(struct bus_id_priv *busid_priv)
 {
 	if (busid_priv->sdev && !busid_priv->shutdown_busid) {
 		busid_priv->shutdown_busid = 1;
 		usbip_event_add(&busid_priv->sdev->ud, SDEV_EVENT_REMOVED);

 		/* wait for the stop of the event handler */
 		usbip_stop_eh(&busid_priv->sdev->ud);
 	}
 }

 /*
  * called in usb_disconnect() or usb_deregister()
  * but only if actconfig(active configuration) exists
  */
 static void stub_disconnect(struct usb_device *udev)
 {
 	struct stub_device *sdev;
 	const char *udev_busid = dev_name(&udev->dev);
 	struct bus_id_priv *busid_priv;
 	int rc;

 	dev_dbg(&udev->dev, "Enter disconnect\n");

 	busid_priv = get_busid_priv(udev_busid);
 	if (!busid_priv) {
 		BUG();
 		return;
 	}

 	sdev = dev_get_drvdata(&udev->dev);

 	/* get stub_device */
 	if (!sdev) {
 		dev_err(&udev->dev, "could not get device");
 		goto call_put_busid_priv;
 	}

 	dev_set_drvdata(&udev->dev, NULL);

 	/*
 	 * NOTE: rx/tx threads are invoked for each usb_device.
 	 */
 	stub_remove_files(&udev->dev);

 	/* release port */
 	rc = usb_hub_release_port(udev->parent, udev->portnum,
 				  (struct usb_dev_state *) udev);
 	if (rc) {
 		dev_dbg(&udev->dev, "unable to release port\n");
 		goto call_put_busid_priv;
 	}

 	/* If usb reset is called from event handler */
 	if (busid_priv->sdev->ud.eh == current)
 		goto call_put_busid_priv;

 	/* shutdown the current connection */
 	shutdown_busid(busid_priv);

 	usb_put_dev(sdev->udev);

 	/* free sdev */
 	busid_priv->sdev = NULL;
 	stub_device_free(sdev);

 	if (busid_priv->status == STUB_BUSID_ALLOC)
 		busid_priv->status = STUB_BUSID_ADDED;

 call_put_busid_priv:
 	put_busid_priv(busid_priv);
 }

 #ifdef CONFIG_PM

 /* These functions need usb_port_suspend and usb_port_resume,
  * which reside in drivers/usb/core/usb.h. Skip for now. */

 static int stub_suspend(struct usb_device *udev, pm_message_t message)
 {
 	dev_dbg(&udev->dev, "stub_suspend\n");

 	return 0;
 }

 static int stub_resume(struct usb_device *udev, pm_message_t message)
 {
 	dev_dbg(&udev->dev, "stub_resume\n");

 	return 0;
 }

 #endif	/* CONFIG_PM */

 struct usb_device_driver stub_driver = {
 	.name		= "usbip-host",
 	.probe		= stub_probe,
 	.disconnect	= stub_disconnect,
 #ifdef CONFIG_PM
 	.suspend	= stub_suspend,
 	.resume		= stub_resume,
 #endif
 	.supports_autosuspend	=	0,
 };
	/*
	* Copyright (C) 2003-2008 Takahiro Hirofuchi
	*
	* This is free software; you can redistribute it and/or modify
	* it under the terms of the GNU General Public License as published by
	* the Free Software Foundation; either version 2 of the License, or
	* (at your option) any later version.
	*
	* This 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. 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.
	*/

	#include <linux/device.h>
	#include <linux/file.h>
	#include <linux/kthread.h>
	#include <linux/module.h>

	#include "usbip_common.h"
	#include "stub.h"

	/*
	* usbip_status shows the status of usbip-host as long as this driver is bound
	* to the target device.
	*/
	static ssize_t usbip_status_show(struct device *dev,
	struct device_attribute attr, char buf)
	{
	struct stub_device *sdev = dev_get_drvdata(dev);
	int status;

	if (!sdev) {
	dev_err(dev, "sdev is null\n");
	return -ENODEV;
	}

	spin_lock_irq(&sdev->ud.lock);
	status = sdev->ud.status;
	spin_unlock_irq(&sdev->ud.lock);

	return snprintf(buf, PAGE_SIZE, "%d\n", status);
	}
	static DEVICE_ATTR_RO(usbip_status);

	/*
	* usbip_sockfd gets a socket descriptor of an established TCP connection that
	* is used to transfer usbip requests by kernel threads. -1 is a magic number
	* by which usbip connection is finished.
	*/
	static ssize_t store_sockfd(struct device dev, struct device_attribute attr,
	const char *buf, size_t count)
	{
	struct stub_device *sdev = dev_get_drvdata(dev);
	int sockfd = 0;
	struct socket *socket;
	int rv;

	if (!sdev) {
	dev_err(dev, "sdev is null\n");
	return -ENODEV;
	}

	rv = sscanf(buf, "%d", &sockfd);
	if (rv != 1)
	return -EINVAL;

	if (sockfd != -1) {
	int err;

	dev_info(dev, "stub up\n");

	spin_lock_irq(&sdev->ud.lock);

	if (sdev->ud.status != SDEV_ST_AVAILABLE) {
	dev_err(dev, "not ready\n");
	goto err;
	}

	socket = sockfd_lookup(sockfd, &err);
	if (!socket)
	goto err;

	sdev->ud.tcp_socket = socket;
	sdev->ud.sockfd = sockfd;

	spin_unlock_irq(&sdev->ud.lock);

	sdev->ud.tcp_rx = kthread_get_run(stub_rx_loop, &sdev->ud,
	"stub_rx");
	sdev->ud.tcp_tx = kthread_get_run(stub_tx_loop, &sdev->ud,
	"stub_tx");

	spin_lock_irq(&sdev->ud.lock);
	sdev->ud.status = SDEV_ST_USED;
	spin_unlock_irq(&sdev->ud.lock);

	} else {
	dev_info(dev, "stub down\n");

	spin_lock_irq(&sdev->ud.lock);
	if (sdev->ud.status != SDEV_ST_USED)
	goto err;

	spin_unlock_irq(&sdev->ud.lock);

	usbip_event_add(&sdev->ud, SDEV_EVENT_DOWN);
	}

	return count;

	err:
	spin_unlock_irq(&sdev->ud.lock);
	return -EINVAL;
	}
	static DEVICE_ATTR(usbip_sockfd, S_IWUSR, NULL, store_sockfd);

	static int stub_add_files(struct device *dev)
	{
	int err = 0;

	err = device_create_file(dev, &dev_attr_usbip_status);
	if (err)
	goto err_status;

	err = device_create_file(dev, &dev_attr_usbip_sockfd);
	if (err)
	goto err_sockfd;

	err = device_create_file(dev, &dev_attr_usbip_debug);
	if (err)
	goto err_debug;

	return 0;

	err_debug:
	device_remove_file(dev, &dev_attr_usbip_sockfd);
	err_sockfd:
	device_remove_file(dev, &dev_attr_usbip_status);
	err_status:
	return err;
	}

	static void stub_remove_files(struct device *dev)
	{
	device_remove_file(dev, &dev_attr_usbip_status);
	device_remove_file(dev, &dev_attr_usbip_sockfd);
	device_remove_file(dev, &dev_attr_usbip_debug);
	}

	static void stub_shutdown_connection(struct usbip_device *ud)
	{
	struct stub_device *sdev = container_of(ud, struct stub_device, ud);

	/*
	* When removing an exported device, kernel panic sometimes occurred
	* and then EIP was sk_wait_data of stub_rx thread. Is this because
	* sk_wait_data returned though stub_rx thread was already finished by
	* step 1?
	*/
	if (ud->tcp_socket) {
	dev_dbg(&sdev->udev->dev, "shutdown sockfd %d\n", ud->sockfd);
	kernel_sock_shutdown(ud->tcp_socket, SHUT_RDWR);
	}

	/* 1. stop threads */
	if (ud->tcp_rx) {
	kthread_stop_put(ud->tcp_rx);
	ud->tcp_rx = NULL;
	}
	if (ud->tcp_tx) {
	kthread_stop_put(ud->tcp_tx);
	ud->tcp_tx = NULL;
	}

	/*
	* 2. close the socket
	*
	* tcp_socket is freed after threads are killed so that usbip_xmit does
	* not touch NULL socket.
	*/
	if (ud->tcp_socket) {
	sockfd_put(ud->tcp_socket);
	ud->tcp_socket = NULL;
	ud->sockfd = -1;
	}

	/* 3. free used data */
	stub_device_cleanup_urbs(sdev);

	/* 4. free stub_unlink */
	{
	unsigned long flags;
	struct stub_unlink unlink, tmp;

	spin_lock_irqsave(&sdev->priv_lock, flags);
	list_for_each_entry_safe(unlink, tmp, &sdev->unlink_tx, list) {
	list_del(&unlink->list);
	kfree(unlink);
	}
	list_for_each_entry_safe(unlink, tmp, &sdev->unlink_free,
	list) {
	list_del(&unlink->list);
	kfree(unlink);
	}
	spin_unlock_irqrestore(&sdev->priv_lock, flags);
	}
	}

	static void stub_device_reset(struct usbip_device *ud)
	{
	struct stub_device *sdev = container_of(ud, struct stub_device, ud);
	struct usb_device *udev = sdev->udev;
	int ret;

	dev_dbg(&udev->dev, "device reset");

	ret = usb_lock_device_for_reset(udev, sdev->interface);
	if (ret < 0) {
	dev_err(&udev->dev, "lock for reset\n");
	spin_lock_irq(&ud->lock);
	ud->status = SDEV_ST_ERROR;
	spin_unlock_irq(&ud->lock);
	return;
	}

	/* try to reset the device */
	ret = usb_reset_device(udev);
	usb_unlock_device(udev);

	spin_lock_irq(&ud->lock);
	if (ret) {
	dev_err(&udev->dev, "device reset\n");
	ud->status = SDEV_ST_ERROR;
	} else {
	dev_info(&udev->dev, "device reset\n");
	ud->status = SDEV_ST_AVAILABLE;
	}
	spin_unlock_irq(&ud->lock);
	}

	static void stub_device_unusable(struct usbip_device *ud)
	{
	spin_lock_irq(&ud->lock);
	ud->status = SDEV_ST_ERROR;
	spin_unlock_irq(&ud->lock);
	}

	/**
	* stub_device_alloc - allocate a new stub_device struct
	* @interface: usb_interface of a new device
	*
	* Allocates and initializes a new stub_device struct.
	*/
	static struct stub_device stub_device_alloc(struct usb_device udev)
	{
	struct stub_device *sdev;
	int busnum = udev->bus->busnum;
	int devnum = udev->devnum;

	dev_dbg(&udev->dev, "allocating stub device");

	/* yes, it's a new device */
	sdev = kzalloc(sizeof(struct stub_device), GFP_KERNEL);
	if (!sdev)
	return NULL;

	sdev->udev = usb_get_dev(udev);

	/*
	* devid is defined with devnum when this driver is first allocated.
	* devnum may change later if a device is reset. However, devid never
	* changes during a usbip connection.
	*/
	sdev->devid = (busnum << 16) \| devnum;
	sdev->ud.side = USBIP_STUB;
	sdev->ud.status = SDEV_ST_AVAILABLE;
	spin_lock_init(&sdev->ud.lock);
	sdev->ud.tcp_socket = NULL;
	sdev->ud.sockfd = -1;

	INIT_LIST_HEAD(&sdev->priv_init);
	INIT_LIST_HEAD(&sdev->priv_tx);
	INIT_LIST_HEAD(&sdev->priv_free);
	INIT_LIST_HEAD(&sdev->unlink_free);
	INIT_LIST_HEAD(&sdev->unlink_tx);
	spin_lock_init(&sdev->priv_lock);

	init_waitqueue_head(&sdev->tx_waitq);

	sdev->ud.eh_ops.shutdown = stub_shutdown_connection;
	sdev->ud.eh_ops.reset = stub_device_reset;
	sdev->ud.eh_ops.unusable = stub_device_unusable;

	usbip_start_eh(&sdev->ud);

	dev_dbg(&udev->dev, "register new device\n");

	return sdev;
	}

	static void stub_device_free(struct stub_device *sdev)
	{
	kfree(sdev);
	}

	static int stub_probe(struct usb_device *udev)
	{
	struct stub_device *sdev = NULL;
	const char *udev_busid = dev_name(&udev->dev);
	struct bus_id_priv *busid_priv;
	int rc = 0;

	dev_dbg(&udev->dev, "Enter probe\n");

	/* check we should claim or not by busid_table */
	busid_priv = get_busid_priv(udev_busid);
	if (!busid_priv \|\| (busid_priv->status == STUB_BUSID_REMOV) \|\|
	(busid_priv->status == STUB_BUSID_OTHER)) {
	dev_info(&udev->dev,
	"%s is not in match_busid table... skip!\n",
	udev_busid);

	/*
	* Return value should be ENODEV or ENOXIO to continue trying
	* other matched drivers by the driver core.
	* See driver_probe_device() in driver/base/dd.c
	*/
	rc = -ENODEV;
	goto call_put_busid_priv;
	}

	if (udev->descriptor.bDeviceClass == USB_CLASS_HUB) {
	dev_dbg(&udev->dev, "%s is a usb hub device... skip!\n",
	udev_busid);
	rc = -ENODEV;
	goto call_put_busid_priv;
	}

	if (!strcmp(udev->bus->bus_name, "vhci_hcd")) {
	dev_dbg(&udev->dev,
	"%s is attached on vhci_hcd... skip!\n",
	udev_busid);

	rc = -ENODEV;
	goto call_put_busid_priv;
	}

	/* ok, this is my device */
	sdev = stub_device_alloc(udev);
	if (!sdev) {
	rc = -ENOMEM;
	goto call_put_busid_priv;
	}

	dev_info(&udev->dev,
	"usbip-host: register new device (bus %u dev %u)\n",
	udev->bus->busnum, udev->devnum);

	busid_priv->shutdown_busid = 0;

	/* set private data to usb_device */
	dev_set_drvdata(&udev->dev, sdev);
	busid_priv->sdev = sdev;
	busid_priv->udev = udev;

	/*
	* Claim this hub port.
	* It doesn't matter what value we pass as owner
	* (struct dev_state) as long as it is unique.
	*/
	rc = usb_hub_claim_port(udev->parent, udev->portnum,
	(struct usb_dev_state *) udev);
	if (rc) {
	dev_dbg(&udev->dev, "unable to claim port\n");
	goto err_port;
	}

	rc = stub_add_files(&udev->dev);
	if (rc) {
	dev_err(&udev->dev, "stub_add_files for %s\n", udev_busid);
	goto err_files;
	}
	busid_priv->status = STUB_BUSID_ALLOC;

	rc = 0;
	goto call_put_busid_priv;

	err_files:
	usb_hub_release_port(udev->parent, udev->portnum,
	(struct usb_dev_state *) udev);
	err_port:
	dev_set_drvdata(&udev->dev, NULL);
	usb_put_dev(udev);
	kthread_stop_put(sdev->ud.eh);

	busid_priv->sdev = NULL;
	stub_device_free(sdev);

	call_put_busid_priv:
	put_busid_priv(busid_priv);
	return rc;
	}

	static void shutdown_busid(struct bus_id_priv *busid_priv)
	{
	if (busid_priv->sdev && !busid_priv->shutdown_busid) {
	busid_priv->shutdown_busid = 1;
	usbip_event_add(&busid_priv->sdev->ud, SDEV_EVENT_REMOVED);

	/* wait for the stop of the event handler */
	usbip_stop_eh(&busid_priv->sdev->ud);
	}
	}

	/*
	* called in usb_disconnect() or usb_deregister()
	* but only if actconfig(active configuration) exists
	*/
	static void stub_disconnect(struct usb_device *udev)
	{
	struct stub_device *sdev;
	const char *udev_busid = dev_name(&udev->dev);
	struct bus_id_priv *busid_priv;
	int rc;

	dev_dbg(&udev->dev, "Enter disconnect\n");

	busid_priv = get_busid_priv(udev_busid);
	if (!busid_priv) {
	BUG();
	return;
	}

	sdev = dev_get_drvdata(&udev->dev);

	/* get stub_device */
	if (!sdev) {
	dev_err(&udev->dev, "could not get device");
	goto call_put_busid_priv;
	}

	dev_set_drvdata(&udev->dev, NULL);

	/*
	* NOTE: rx/tx threads are invoked for each usb_device.
	*/
	stub_remove_files(&udev->dev);

	/* release port */
	rc = usb_hub_release_port(udev->parent, udev->portnum,
	(struct usb_dev_state *) udev);
	if (rc) {
	dev_dbg(&udev->dev, "unable to release port\n");
	goto call_put_busid_priv;
	}

	/* If usb reset is called from event handler */
	if (busid_priv->sdev->ud.eh == current)
	goto call_put_busid_priv;

	/* shutdown the current connection */
	shutdown_busid(busid_priv);

	usb_put_dev(sdev->udev);

	/* free sdev */
	busid_priv->sdev = NULL;
	stub_device_free(sdev);

	if (busid_priv->status == STUB_BUSID_ALLOC)
	busid_priv->status = STUB_BUSID_ADDED;

	call_put_busid_priv:
	put_busid_priv(busid_priv);
	}

	#ifdef CONFIG_PM

	/* These functions need usb_port_suspend and usb_port_resume,
	* which reside in drivers/usb/core/usb.h. Skip for now. */

	static int stub_suspend(struct usb_device *udev, pm_message_t message)
	{
	dev_dbg(&udev->dev, "stub_suspend\n");

	return 0;
	}

	static int stub_resume(struct usb_device *udev, pm_message_t message)
	{
	dev_dbg(&udev->dev, "stub_resume\n");

	return 0;
	}

	#endif /* CONFIG_PM */

	struct usb_device_driver stub_driver = {
	.name = "usbip-host",
	.probe = stub_probe,
	.disconnect = stub_disconnect,
	#ifdef CONFIG_PM
	.suspend = stub_suspend,
	.resume = stub_resume,
	#endif
	.supports_autosuspend = 0,
	};