Staging: USB/IP: add host driver

This adds the USB IP client driver

Brian Merrell cleaned up a lot of this code and submitted it for
inclusion.  Greg also did a lot of cleanup.

Signed-off-by: Brian G. Merrell <bgmerrell@novell.com>
Cc: Takahiro Hirofuchi <hirofuchi@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

7 files changed, 1878 insertions, 0 deletions

diff --git a/drivers/staging/usbip/Kconfig b/drivers/staging/usbip/Kconfig
index c4d68e1581fc..7426235ccc44 100644
--- a/drivers/staging/usbip/Kconfig
+++ b/drivers/staging/usbip/Kconfig
@@ -23,3 +23,14 @@ config USB_IP_VHCI_HCD
 
 	 To compile this driver as a module, choose M here: the
 	 module will be called vhci_hcd.
+
+config USB_IP_HOST
+	tristate "USB IP host driver"
+	depends on USB_IP_COMMON
+	default N
+	---help---
+	 This enables the USB IP device driver which will run on the
+	 host machine.
+
+	 To compile this driver as a module, choose M here: the
+	 module will be called usbip.
diff --git a/drivers/staging/usbip/Makefile b/drivers/staging/usbip/Makefile
index 6ef4c3913f45..179f4211f96b 100644
--- a/drivers/staging/usbip/Makefile
+++ b/drivers/staging/usbip/Makefile
@@ -4,6 +4,9 @@ usbip_common_mod-objs := usbip_common.o usbip_event.o
 obj-$(CONFIG_USB_IP_VHCI_HCD) += vhci-hcd.o
 vhci-hcd-objs := vhci_sysfs.o vhci_tx.o vhci_rx.o vhci_hcd.o
 
+obj-$(CONFIG_USB_IP_HOST) += usbip.o
+usbip-objs := stub_dev.o stub_main.o stub_rx.o stub_tx.o
+
 ifeq ($(CONFIG_USB_DEBUG),y)
 	EXTRA_CFLAGS += -DDEBUG
 endif
diff --git a/drivers/staging/usbip/stub.h b/drivers/staging/usbip/stub.h
new file mode 100644
index 000000000000..f541a3a83bd3
--- /dev/null
+++ b/drivers/staging/usbip/stub.h
@@ -0,0 +1,95 @@
+/*
+ * 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/kernel.h>
+#include <linux/list.h>
+#include <linux/spinlock.h>
+#include <linux/slab.h>
+#include <linux/string.h>
+#include <linux/module.h>
+#include <linux/net.h>
+
+struct stub_device {
+	struct usb_interface *interface;
+	struct list_head list;
+
+	struct usbip_device ud;
+	__u32 devid;
+
+	/*
+	 * stub_priv preserves private data of each urb.
+	 * It is allocated as stub_priv_cache and assigned to urb->context.
+	 *
+	 * stub_priv is always linked to any one of 3 lists;
+	 *	priv_init: linked to this until the comletion of a urb.
+	 *	priv_tx  : linked to this after the completion of a urb.
+	 *	priv_free: linked to this after the sending of the result.
+	 *
+	 * Any of these list operations should be locked by priv_lock.
+	 */
+	spinlock_t priv_lock;
+	struct list_head priv_init;
+	struct list_head priv_tx;
+	struct list_head priv_free;
+
+	/* see comments for unlinking in stub_rx.c */
+	struct list_head unlink_tx;
+	struct list_head unlink_free;
+
+
+	wait_queue_head_t tx_waitq;
+};
+
+/* private data into urb->priv */
+struct stub_priv {
+	unsigned long seqnum;
+	struct list_head list;
+	struct stub_device *sdev;
+	struct urb *urb;
+
+	int unlinking;
+};
+
+struct stub_unlink {
+	unsigned long seqnum;
+	struct list_head list;
+	__u32 status;
+};
+
+
+extern struct kmem_cache *stub_priv_cache;
+
+
+/*-------------------------------------------------------------------------*/
+/* prototype declarations */
+
+/* stub_tx.c */
+void stub_complete(struct urb *);
+void stub_tx_loop(struct usbip_task *);
+
+/* stub_dev.c */
+extern struct usb_driver stub_driver;
+
+/* stub_rx.c */
+void stub_rx_loop(struct usbip_task *);
+void stub_enqueue_ret_unlink(struct stub_device *, __u32, __u32);
+
+/* stub_main.c */
+int match_busid(char *busid);
+void stub_device_cleanup_urbs(struct stub_device *sdev);
diff --git a/drivers/staging/usbip/stub_dev.c b/drivers/staging/usbip/stub_dev.c
new file mode 100644
index 000000000000..ee455a087eaf
--- /dev/null
+++ b/drivers/staging/usbip/stub_dev.c
@@ -0,0 +1,483 @@
+/*
+ * 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 "usbip_common.h"
+#include "stub.h"
+
+
+
+static int stub_probe(struct usb_interface *interface,
+				const struct usb_device_id *id);
+static void stub_disconnect(struct usb_interface *interface);
+
+
+/*
+ * Define device IDs here if you want to explicitly limit exportable devices.
+ * In the most cases, wild card matching will be ok because driver binding can
+ * be changed dynamically by a userland program.
+ */
+static struct usb_device_id stub_table[] = {
+#if 0
+	/* just an example */
+	{ USB_DEVICE(0x05ac, 0x0301) },   /* Mac 1 button mouse */
+	{ USB_DEVICE(0x0430, 0x0009) },   /* Plat Home Keyboard */
+	{ USB_DEVICE(0x059b, 0x0001) },   /* Iomega USB Zip 100 */
+	{ USB_DEVICE(0x04b3, 0x4427) },   /* IBM USB CD-ROM */
+	{ USB_DEVICE(0x05a9, 0xa511) },   /* LifeView USB cam */
+	{ USB_DEVICE(0x55aa, 0x0201) },   /* Imation card reader */
+	{ USB_DEVICE(0x046d, 0x0870) },   /* Qcam Express(QV-30) */
+	{ USB_DEVICE(0x04bb, 0x0101) },   /* IO-DATA HD 120GB */
+	{ USB_DEVICE(0x04bb, 0x0904) },   /* IO-DATA USB-ET/TX */
+	{ USB_DEVICE(0x04bb, 0x0201) },   /* IO-DATA USB-ET/TX */
+	{ USB_DEVICE(0x08bb, 0x2702) },   /* ONKYO USB Speaker */
+	{ USB_DEVICE(0x046d, 0x08b2) },   /* Logicool Qcam 4000 Pro */
+#endif
+	/* magic for wild card */
+	{ .driver_info = 1 },
+	{ 0, }                                     /* Terminating entry */
+};
+MODULE_DEVICE_TABLE(usb, stub_table);
+
+struct usb_driver stub_driver = {
+	.name		= "usbip",
+	.probe		= stub_probe,
+	.disconnect	= stub_disconnect,
+	.id_table	= stub_table,
+};
+
+
+/*-------------------------------------------------------------------------*/
+
+/* Define sysfs entries for a usbip-bound device */
+
+
+/*
+ * usbip_status shows status of usbip as long as this driver is bound to the
+ * target device.
+ */
+static ssize_t show_status(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(&sdev->ud.lock);
+	status = sdev->ud.status;
+	spin_unlock(&sdev->ud.lock);
+
+	return snprintf(buf, PAGE_SIZE, "%d\n", status);
+}
+static DEVICE_ATTR(usbip_status, S_IRUGO, show_status, NULL);
+
+/*
+ * 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;
+
+	if (!sdev) {
+		dev_err(dev, "sdev is null\n");
+		return -ENODEV;
+	}
+
+	sscanf(buf, "%d", &sockfd);
+
+	if (sockfd != -1) {
+		dev_info(dev, "stub up\n");
+
+		spin_lock(&sdev->ud.lock);
+
+		if (sdev->ud.status != SDEV_ST_AVAILABLE) {
+			dev_err(dev, "not ready\n");
+			spin_unlock(&sdev->ud.lock);
+			return -EINVAL;
+		}
+
+		socket = sockfd_to_socket(sockfd);
+		if (!socket) {
+			spin_unlock(&sdev->ud.lock);
+			return -EINVAL;
+		}
+
+#if 0
+		setnodelay(socket);
+		setkeepalive(socket);
+		setreuse(socket);
+#endif
+
+		sdev->ud.tcp_socket = socket;
+
+		spin_unlock(&sdev->ud.lock);
+
+		usbip_start_threads(&sdev->ud);
+
+		spin_lock(&sdev->ud.lock);
+		sdev->ud.status = SDEV_ST_USED;
+		spin_unlock(&sdev->ud.lock);
+
+	} else {
+		dev_info(dev, "stub down\n");
+
+		spin_lock(&sdev->ud.lock);
+		if (sdev->ud.status != SDEV_ST_USED) {
+			spin_unlock(&sdev->ud.lock);
+			return -EINVAL;
+		}
+		spin_unlock(&sdev->ud.lock);
+
+		usbip_event_add(&sdev->ud, SDEV_EVENT_DOWN);
+	}
+
+	return count;
+}
+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);
+}
+
+
+
+/*-------------------------------------------------------------------------*/
+
+/* Event handler functions called by an event handler thread */
+
+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) {
+		udbg("shutdown tcp_socket %p\n", ud->tcp_socket);
+		kernel_sock_shutdown(ud->tcp_socket, SHUT_RDWR);
+	}
+
+	/* 1. stop threads */
+	usbip_stop_threads(ud);
+
+	/* 2. close the socket */
+	/*
+	 * tcp_socket is freed after threads are killed.
+	 * So usbip_xmit do not touch NULL socket.
+	 */
+	if (ud->tcp_socket) {
+		sock_release(ud->tcp_socket);
+		ud->tcp_socket = NULL;
+	}
+
+	/* 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 = interface_to_usbdev(sdev->interface);
+	int ret;
+
+	udbg("device reset");
+	ret = usb_lock_device_for_reset(udev, sdev->interface);
+	if (ret < 0) {
+		dev_err(&udev->dev, "lock for reset\n");
+
+		spin_lock(&ud->lock);
+		ud->status = SDEV_ST_ERROR;
+		spin_unlock(&ud->lock);
+
+		return;
+	}
+
+	/* try to reset the device */
+	ret = usb_reset_device(udev);
+
+	usb_unlock_device(udev);
+
+	spin_lock(&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(&ud->lock);
+
+	return;
+}
+
+static void stub_device_unusable(struct usbip_device *ud)
+{
+	spin_lock(&ud->lock);
+	ud->status = SDEV_ST_ERROR;
+	spin_unlock(&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_interface *interface)
+{
+	struct stub_device *sdev;
+	int busnum = interface_to_busnum(interface);
+	int devnum = interface_to_devnum(interface);
+
+	dev_dbg(&interface->dev, "allocating stub device");
+
+	/* yes, it's a new device */
+	sdev = kzalloc(sizeof(struct stub_device), GFP_KERNEL);
+	if (!sdev) {
+		dev_err(&interface->dev, "no memory for stub_device\n");
+		return NULL;
+	}
+
+	sdev->interface = interface;
+
+	/*
+	 * 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;
+
+	usbip_task_init(&sdev->ud.tcp_rx, "stub_rx", stub_rx_loop);
+	usbip_task_init(&sdev->ud.tcp_tx, "stub_tx", stub_tx_loop);
+
+	sdev->ud.side = USBIP_STUB;
+	sdev->ud.status = SDEV_ST_AVAILABLE;
+	/* sdev->ud.lock = SPIN_LOCK_UNLOCKED; */
+	spin_lock_init(&sdev->ud.lock);
+	sdev->ud.tcp_socket = NULL;
+
+	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);
+	/* sdev->priv_lock = SPIN_LOCK_UNLOCKED; */
+	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);
+
+	udbg("register new interface\n");
+	return sdev;
+}
+
+static int stub_device_free(struct stub_device *sdev)
+{
+	if (!sdev)
+		return -EINVAL;
+
+	kfree(sdev);
+	udbg("kfree udev ok\n");
+
+	return 0;
+}
+
+
+/*-------------------------------------------------------------------------*/
+
+/*
+ * If a usb device has multiple active interfaces, this driver is bound to all
+ * the active interfaces. However, usbip exports *a* usb device (i.e., not *an*
+ * active interface). Currently, a userland program must ensure that it
+ * looks at the usbip's sysfs entries of only the first active interface.
+ *
+ * TODO: use "struct usb_device_driver" to bind a usb device.
+ * However, it seems it is not fully supported in mainline kernel yet
+ * (2.6.19.2).
+ */
+static int stub_probe(struct usb_interface *interface,
+		      const struct usb_device_id *id)
+{
+	struct usb_device *udev = interface_to_usbdev(interface);
+	struct stub_device *sdev = NULL;
+	char *udev_busid = interface->dev.parent->bus_id;
+	int err = 0;
+
+	dev_dbg(&interface->dev, "Enter\n");
+
+	/* check we should claim or not by busid_table */
+	if (match_busid(udev_busid)) {
+		dev_info(&interface->dev,
+			 "this device %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
+		 */
+		return -ENODEV;
+	}
+
+	if (udev->descriptor.bDeviceClass ==  USB_CLASS_HUB) {
+		udbg("this device %s is a usb hub device. skip!\n",
+								udev_busid);
+		return -ENODEV;
+	}
+
+	if (!strcmp(udev->bus->bus_name, "vhci_hcd")) {
+		udbg("this device %s is attached on vhci_hcd. skip!\n",
+								udev_busid);
+		return -ENODEV;
+	}
+
+	/* ok. this is my device. */
+	sdev = stub_device_alloc(interface);
+	if (!sdev)
+		return -ENOMEM;
+
+	dev_info(&interface->dev, "USB/IP Stub: register a new interface "
+		 "(bus %u dev %u ifn %u)\n", udev->bus->busnum, udev->devnum,
+		 interface->cur_altsetting->desc.bInterfaceNumber);
+
+	/* set private data to usb_interface */
+	usb_set_intfdata(interface, sdev);
+
+	err = stub_add_files(&interface->dev);
+	if (err) {
+		dev_err(&interface->dev, "create sysfs files for %s\n",
+			udev_busid);
+		return err;
+	}
+
+	return 0;
+}
+
+
+/*
+ * called in usb_disconnect() or usb_deregister()
+ * but only if actconfig(active configuration) exists
+ */
+static void stub_disconnect(struct usb_interface *interface)
+{
+	struct stub_device *sdev = usb_get_intfdata(interface);
+
+	udbg("Enter\n");
+
+	/* get stub_device */
+	if (!sdev) {
+		err(" could not get device from inteface data");
+		/* BUG(); */
+		return;
+	}
+
+	usb_set_intfdata(interface, NULL);
+
+
+	/*
+	 * NOTE:
+	 * rx/tx threads are invoked for each usb_device.
+	 */
+	stub_remove_files(&interface->dev);
+
+	/* 1. shutdown the current connection */
+	usbip_event_add(&sdev->ud, SDEV_EVENT_REMOVED);
+
+	/* 2. wait for the stop of the event handler */
+	usbip_stop_eh(&sdev->ud);
+
+	/* 3. free sdev */
+	stub_device_free(sdev);
+
+
+	udbg("bye\n");
+}
diff --git a/drivers/staging/usbip/stub_main.c b/drivers/staging/usbip/stub_main.c
new file mode 100644
index 000000000000..c665d7f1ca9a
--- /dev/null
+++ b/drivers/staging/usbip/stub_main.c
@@ -0,0 +1,300 @@
+/*
+ * 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 "usbip_common.h"
+#include "stub.h"
+
+/* Version Information */
+#define DRIVER_VERSION "1.0"
+#define DRIVER_AUTHOR "Takahiro Hirofuchi"
+#define DRIVER_DESC "Stub Driver for USB/IP"
+
+/* stub_priv is allocated from stub_priv_cache */
+struct kmem_cache *stub_priv_cache;
+
+/*-------------------------------------------------------------------------*/
+
+/* Define sysfs entries for the usbip driver */
+
+
+/*
+ * busid_tables defines matching busids that usbip can grab. A user can change
+ * dynamically what device is locally used and what device is exported to a
+ * remote host.
+ */
+#define MAX_BUSID 16
+static char busid_table[MAX_BUSID][BUS_ID_SIZE];
+static spinlock_t busid_table_lock;
+
+
+int match_busid(char *busid)
+{
+	int i;
+
+	spin_lock(&busid_table_lock);
+
+	for (i = 0; i < MAX_BUSID; i++)
+		if (busid_table[i][0])
+			if (!strncmp(busid_table[i], busid, BUS_ID_SIZE)) {
+				/* already registerd */
+				spin_unlock(&busid_table_lock);
+				return 0;
+			}
+
+	spin_unlock(&busid_table_lock);
+
+	return 1;
+}
+
+static ssize_t show_match_busid(struct device_driver *drv, char *buf)
+{
+	int i;
+	char *out = buf;
+
+	spin_lock(&busid_table_lock);
+
+	for (i = 0; i < MAX_BUSID; i++)
+		if (busid_table[i][0])
+			out += sprintf(out, "%s ", busid_table[i]);
+
+	spin_unlock(&busid_table_lock);
+
+	out += sprintf(out, "\n");
+
+	return out - buf;
+}
+
+static int add_match_busid(char *busid)
+{
+	int i;
+
+	if (!match_busid(busid))
+		return 0;
+
+	spin_lock(&busid_table_lock);
+
+	for (i = 0; i < MAX_BUSID; i++)
+		if (!busid_table[i][0]) {
+			strncpy(busid_table[i], busid, BUS_ID_SIZE);
+			spin_unlock(&busid_table_lock);
+			return 0;
+		}
+
+	spin_unlock(&busid_table_lock);
+
+	return -1;
+}
+
+static int del_match_busid(char *busid)
+{
+	int i;
+
+	spin_lock(&busid_table_lock);
+
+	for (i = 0; i < MAX_BUSID; i++)
+		if (!strncmp(busid_table[i], busid, BUS_ID_SIZE)) {
+			/* found */
+			memset(busid_table[i], 0, BUS_ID_SIZE);
+			spin_unlock(&busid_table_lock);
+			return 0;
+		}
+
+	spin_unlock(&busid_table_lock);
+
+	return -1;
+}
+
+static ssize_t store_match_busid(struct device_driver *dev, const char *buf,
+		size_t count)
+{
+	int len;
+	char busid[BUS_ID_SIZE];
+
+	if (count < 5)
+		return -EINVAL;
+
+	/* strnlen() does not include \0 */
+	len = strnlen(buf + 4, BUS_ID_SIZE);
+
+	/* busid needs to include \0 termination */
+	if (!(len < BUS_ID_SIZE))
+		return -EINVAL;
+
+	strncpy(busid, buf + 4, BUS_ID_SIZE);
+
+
+	if (!strncmp(buf, "add ", 4)) {
+		if (add_match_busid(busid) < 0)
+			return -ENOMEM;
+		else {
+			udbg("add busid %s\n", busid);
+			return count;
+		}
+	} else if (!strncmp(buf, "del ", 4)) {
+		if (del_match_busid(busid) < 0)
+			return -ENODEV;
+		else {
+			udbg("del busid %s\n", busid);
+			return count;
+		}
+	} else
+		return -EINVAL;
+}
+
+static DRIVER_ATTR(match_busid, S_IRUSR|S_IWUSR, show_match_busid,
+							store_match_busid);
+
+
+
+/*-------------------------------------------------------------------------*/
+
+/* Cleanup functions used to free private data */
+
+static struct stub_priv *stub_priv_pop_from_listhead(struct list_head *listhead)
+{
+	struct stub_priv *priv, *tmp;
+
+	list_for_each_entry_safe(priv, tmp, listhead, list) {
+		list_del(&priv->list);
+		return priv;
+	}
+
+	return NULL;
+}
+
+static struct stub_priv *stub_priv_pop(struct stub_device *sdev)
+{
+	unsigned long flags;
+	struct stub_priv *priv;
+
+	spin_lock_irqsave(&sdev->priv_lock, flags);
+
+	priv = stub_priv_pop_from_listhead(&sdev->priv_init);
+	if (priv) {
+		spin_unlock_irqrestore(&sdev->priv_lock, flags);
+		return priv;
+	}
+
+	priv = stub_priv_pop_from_listhead(&sdev->priv_tx);
+	if (priv) {
+		spin_unlock_irqrestore(&sdev->priv_lock, flags);
+		return priv;
+	}
+
+	priv = stub_priv_pop_from_listhead(&sdev->priv_free);
+	if (priv) {
+		spin_unlock_irqrestore(&sdev->priv_lock, flags);
+		return priv;
+	}
+
+	spin_unlock_irqrestore(&sdev->priv_lock, flags);
+	return NULL;
+}
+
+void stub_device_cleanup_urbs(struct stub_device *sdev)
+{
+	struct stub_priv *priv;
+
+	udbg("free sdev %p\n", sdev);
+
+	while ((priv = stub_priv_pop(sdev))) {
+		struct urb *urb = priv->urb;
+
+		udbg("   free urb %p\n", urb);
+		usb_kill_urb(urb);
+
+		kmem_cache_free(stub_priv_cache, priv);
+
+		if (urb->transfer_buffer != NULL)
+			kfree(urb->transfer_buffer);
+
+		if (urb->setup_packet != NULL)
+			kfree(urb->setup_packet);
+
+		usb_free_urb(urb);
+	}
+}
+
+
+/*-------------------------------------------------------------------------*/
+
+static int __init usb_stub_init(void)
+{
+	int ret;
+
+	stub_priv_cache = kmem_cache_create("stub_priv",
+					    sizeof(struct stub_priv), 0,
+					    SLAB_HWCACHE_ALIGN, NULL);
+
+	if (!stub_priv_cache) {
+		printk(KERN_ERR KBUILD_MODNAME
+		       ": create stub_priv_cache error\n");
+		return -ENOMEM;
+	}
+
+	ret = usb_register(&stub_driver);
+	if (ret) {
+		printk(KERN_ERR KBUILD_MODNAME ": usb_register failed %d\n",
+		       ret);
+		goto error_usb_register;
+	}
+
+	printk(KERN_INFO KBUILD_MODNAME ":"
+	       DRIVER_DESC ":" DRIVER_VERSION "\n");
+
+	memset(busid_table, 0, sizeof(busid_table));
+	spin_lock_init(&busid_table_lock);
+
+	ret = driver_create_file(&stub_driver.drvwrap.driver,
+				 &driver_attr_match_busid);
+
+	if (ret) {
+		printk(KERN_ERR KBUILD_MODNAME ": create driver sysfs\n");
+		goto error_create_file;
+	}
+
+	return ret;
+error_create_file:
+	usb_deregister(&stub_driver);
+error_usb_register:
+	kmem_cache_destroy(stub_priv_cache);
+	return ret;
+}
+
+static void __exit usb_stub_exit(void)
+{
+	driver_remove_file(&stub_driver.drvwrap.driver,
+			   &driver_attr_match_busid);
+
+	/*
+	 * deregister() calls stub_disconnect() for all devices. Device
+	 * specific data is cleared in stub_disconnect().
+	 */
+	usb_deregister(&stub_driver);
+
+	kmem_cache_destroy(stub_priv_cache);
+}
+
+module_init(usb_stub_init);
+module_exit(usb_stub_exit);
+
+MODULE_AUTHOR(DRIVER_AUTHOR);
+MODULE_DESCRIPTION(DRIVER_DESC);
+MODULE_LICENSE("GPL");
diff --git a/drivers/staging/usbip/stub_rx.c b/drivers/staging/usbip/stub_rx.c
new file mode 100644
index 000000000000..36ce898fced5
--- /dev/null
+++ b/drivers/staging/usbip/stub_rx.c
@@ -0,0 +1,615 @@
+/*
+ * 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 "usbip_common.h"
+#include "stub.h"
+#include "../../usb/core/hcd.h"
+
+
+static int is_clear_halt_cmd(struct urb *urb)
+{
+	struct usb_ctrlrequest *req;
+
+	req = (struct usb_ctrlrequest *) urb->setup_packet;
+
+	 return (req->bRequest == USB_REQ_CLEAR_FEATURE) &&
+		 (req->bRequestType == USB_RECIP_ENDPOINT) &&
+		 (req->wValue == USB_ENDPOINT_HALT);
+}
+
+static int is_set_interface_cmd(struct urb *urb)
+{
+	struct usb_ctrlrequest *req;
+
+	req = (struct usb_ctrlrequest *) urb->setup_packet;
+
+	return (req->bRequest == USB_REQ_SET_INTERFACE) &&
+		   (req->bRequestType == USB_RECIP_INTERFACE);
+}
+
+static int is_set_configuration_cmd(struct urb *urb)
+{
+	struct usb_ctrlrequest *req;
+
+	req = (struct usb_ctrlrequest *) urb->setup_packet;
+
+	return (req->bRequest == USB_REQ_SET_CONFIGURATION) &&
+		   (req->bRequestType == USB_RECIP_DEVICE);
+}
+
+static int is_reset_device_cmd(struct urb *urb)
+{
+	struct usb_ctrlrequest *req;
+	__u16 value;
+	__u16 index;
+
+	req = (struct usb_ctrlrequest *) urb->setup_packet;
+	value = le16_to_cpu(req->wValue);
+	index = le16_to_cpu(req->wIndex);
+
+	if ((req->bRequest == USB_REQ_SET_FEATURE) &&
+			(req->bRequestType == USB_RT_PORT) &&
+			(value = USB_PORT_FEAT_RESET)) {
+		dbg_stub_rx("reset_device_cmd, port %u\n", index);
+		return 1;
+	} else
+		return 0;
+}
+
+static int tweak_clear_halt_cmd(struct urb *urb)
+{
+	struct usb_ctrlrequest *req;
+	int target_endp;
+	int target_dir;
+	int target_pipe;
+	int ret;
+
+	req = (struct usb_ctrlrequest *) urb->setup_packet;
+
+	/*
+	 * The stalled endpoint is specified in the wIndex value. The endpoint
+	 * of the urb is the target of this clear_halt request (i.e., control
+	 * endpoint).
+	 */
+	target_endp = le16_to_cpu(req->wIndex) & 0x000f;
+
+	/* the stalled endpoint direction is IN or OUT?. USB_DIR_IN is 0x80.  */
+	target_dir = le16_to_cpu(req->wIndex) & 0x0080;
+
+	if (target_dir)
+		target_pipe = usb_rcvctrlpipe(urb->dev, target_endp);
+	else
+		target_pipe = usb_sndctrlpipe(urb->dev, target_endp);
+
+	ret = usb_clear_halt(urb->dev, target_pipe);
+	if (ret < 0)
+		uinfo("clear_halt error: devnum %d endp %d, %d\n",
+				urb->dev->devnum, target_endp, ret);
+	else
+		uinfo("clear_halt done: devnum %d endp %d\n",
+				urb->dev->devnum, target_endp);
+
+	return ret;
+}
+
+static int tweak_set_interface_cmd(struct urb *urb)
+{
+	struct usb_ctrlrequest *req;
+	__u16 alternate;
+	__u16 interface;
+	int ret;
+
+	req = (struct usb_ctrlrequest *) urb->setup_packet;
+	alternate = le16_to_cpu(req->wValue);
+	interface = le16_to_cpu(req->wIndex);
+
+	dbg_stub_rx("set_interface: inf %u alt %u\n", interface, alternate);
+
+	ret = usb_set_interface(urb->dev, interface, alternate);
+	if (ret < 0)
+		uinfo("set_interface error: inf %u alt %u, %d\n",
+				interface, alternate, ret);
+	else
+		uinfo("set_interface done: inf %u alt %u\n",
+							interface,
+							alternate);
+
+	return ret;
+}
+
+static int tweak_set_configuration_cmd(struct urb *urb)
+{
+	struct usb_ctrlrequest *req;
+	__u16 config;
+
+	req = (struct usb_ctrlrequest *) urb->setup_packet;
+	config = le16_to_cpu(req->wValue);
+
+	/*
+	 * I have never seen a multi-config device. Very rare.
+	 * For most devices, this will be called to choose a default
+	 * configuration only once in an initialization phase.
+	 *
+	 * set_configuration may change a device configuration and its device
+	 * drivers will be unbound and assigned for a new device configuration.
+	 * This means this usbip driver will be also unbound when called, then
+	 * eventually reassigned to the device as far as driver matching
+	 * condition is kept.
+	 *
+	 * Unfortunatelly, an existing usbip connection will be dropped
+	 * due to this driver unbinding. So, skip here.
+	 * A user may need to set a special configuration value before
+	 * exporting the device.
+	 */
+	uinfo("set_configuration (%d) to %s\n", config, urb->dev->dev.bus_id);
+	uinfo("but, skip!\n");
+
+	return 0;
+	/* return usb_driver_set_configuration(urb->dev, config); */
+}
+
+static int tweak_reset_device_cmd(struct urb *urb)
+{
+	struct usb_ctrlrequest *req;
+	__u16 value;
+	__u16 index;
+	int ret;
+
+	req = (struct usb_ctrlrequest *) urb->setup_packet;
+	value = le16_to_cpu(req->wValue);
+	index = le16_to_cpu(req->wIndex);
+
+	uinfo("reset_device (port %d) to %s\n", index, urb->dev->dev.bus_id);
+
+	/* all interfaces should be owned by usbip driver, so just reset it.  */
+	ret = usb_lock_device_for_reset(urb->dev, NULL);
+	if (ret < 0) {
+		dev_err(&urb->dev->dev, "lock for reset\n");
+		return ret;
+	}
+
+	/* try to reset the device */
+	ret = usb_reset_device(urb->dev);
+	if (ret < 0)
+		dev_err(&urb->dev->dev, "device reset\n");
+
+	usb_unlock_device(urb->dev);
+
+	return ret;
+}
+
+/*
+ * clear_halt, set_interface, and set_configuration require special tricks.
+ */
+static void tweak_special_requests(struct urb *urb)
+{
+	if (!urb || !urb->setup_packet)
+		return;
+
+	if (usb_pipetype(urb->pipe) != PIPE_CONTROL)
+		return;
+
+	if (is_clear_halt_cmd(urb))
+		/* tweak clear_halt */
+		 tweak_clear_halt_cmd(urb);
+
+	else if (is_set_interface_cmd(urb))
+		/* tweak set_interface */
+		tweak_set_interface_cmd(urb);
+
+	else if (is_set_configuration_cmd(urb))
+		/* tweak set_configuration */
+		tweak_set_configuration_cmd(urb);
+
+	else if (is_reset_device_cmd(urb))
+		tweak_reset_device_cmd(urb);
+	else
+		dbg_stub_rx("no need to tweak\n");
+}
+
+/*
+ * stub_recv_unlink() unlinks the URB by a call to usb_unlink_urb().
+ * By unlinking the urb asynchronously, stub_rx can continuously
+ * process coming urbs.  Even if the urb is unlinked, its completion
+ * handler will be called and stub_tx will send a return pdu.
+ *
+ * See also comments about unlinking strategy in vhci_hcd.c.
+ */
+static int stub_recv_cmd_unlink(struct stub_device *sdev,
+						struct usbip_header *pdu)
+{
+	struct list_head *listhead = &sdev->priv_init;
+	struct list_head *ptr;
+	unsigned long flags;
+
+	struct stub_priv *priv;
+
+
+	spin_lock_irqsave(&sdev->priv_lock, flags);
+
+	for (ptr = listhead->next; ptr != listhead; ptr = ptr->next) {
+		priv = list_entry(ptr, struct stub_priv, list);
+		if (priv->seqnum == pdu->u.cmd_unlink.seqnum) {
+			int ret;
+
+			dev_info(&priv->urb->dev->dev, "unlink urb %p\n",
+				 priv->urb);
+
+			/*
+			 * This matched urb is not completed yet (i.e., be in
+			 * flight in usb hcd hardware/driver). Now we are
+			 * cancelling it. The unlinking flag means that we are
+			 * now not going to return the normal result pdu of a
+			 * submission request, but going to return a result pdu
+			 * of the unlink request.
+			 */
+			priv->unlinking = 1;
+
+			/*
+			 * In the case that unlinking flag is on, prev->seqnum
+			 * is changed from the seqnum of the cancelling urb to
+			 * the seqnum of the unlink request. This will be used
+			 * to make the result pdu of the unlink request.
+			 */
+			priv->seqnum = pdu->base.seqnum;
+
+			spin_unlock_irqrestore(&sdev->priv_lock, flags);
+
+			/*
+			 * usb_unlink_urb() is now out of spinlocking to avoid
+			 * spinlock recursion since stub_complete() is
+			 * sometimes called in this context but not in the
+			 * interrupt context.  If stub_complete() is executed
+			 * before we call usb_unlink_urb(), usb_unlink_urb()
+			 * will return an error value. In this case, stub_tx
+			 * will return the result pdu of this unlink request
+			 * though submission is completed and actual unlinking
+			 * is not executed. OK?
+			 */
+			/* In the above case, urb->status is not -ECONNRESET,
+			 * so a driver in a client host will know the failure
+			 * of the unlink request ?
+			 */
+			ret = usb_unlink_urb(priv->urb);
+			if (ret != -EINPROGRESS)
+				dev_err(&priv->urb->dev->dev,
+					"failed to unlink a urb %p, ret %d\n",
+					priv->urb, ret);
+			return 0;
+		}
+	}
+
+	dbg_stub_rx("seqnum %d is not pending\n", pdu->u.cmd_unlink.seqnum);
+
+	/*
+	 * The urb of the unlink target is not found in priv_init queue. It was
+	 * already completed and its results is/was going to be sent by a
+	 * CMD_RET pdu. In this case, usb_unlink_urb() is not needed. We only
+	 * return the completeness of this unlink request to vhci_hcd.
+	 */
+	stub_enqueue_ret_unlink(sdev, pdu->base.seqnum, 0);
+
+	spin_unlock_irqrestore(&sdev->priv_lock, flags);
+
+
+	return 0;
+}
+
+static int valid_request(struct stub_device *sdev, struct usbip_header *pdu)
+{
+	struct usbip_device *ud = &sdev->ud;
+
+	if (pdu->base.devid == sdev->devid) {
+		spin_lock(&ud->lock);
+		if (ud->status == SDEV_ST_USED) {
+			/* A request is valid. */
+			spin_unlock(&ud->lock);
+			return 1;
+		}
+		spin_unlock(&ud->lock);
+	}
+
+	return 0;
+}
+
+static struct stub_priv *stub_priv_alloc(struct stub_device *sdev,
+					 struct usbip_header *pdu)
+{
+	struct stub_priv *priv;
+	struct usbip_device *ud = &sdev->ud;
+	unsigned long flags;
+
+	spin_lock_irqsave(&sdev->priv_lock, flags);
+
+	priv = kmem_cache_alloc(stub_priv_cache, GFP_ATOMIC);
+	if (!priv) {
+		dev_err(&sdev->interface->dev, "alloc stub_priv\n");
+		spin_unlock_irqrestore(&sdev->priv_lock, flags);
+		usbip_event_add(ud, SDEV_EVENT_ERROR_MALLOC);
+		return NULL;
+	}
+
+	memset(priv, 0, sizeof(struct stub_priv));
+
+	priv->seqnum = pdu->base.seqnum;
+	priv->sdev = sdev;
+
+	/*
+	 * After a stub_priv is linked to a list_head,
+	 * our error handler can free allocated data.
+	 */
+	list_add_tail(&priv->list, &sdev->priv_init);
+
+	spin_unlock_irqrestore(&sdev->priv_lock, flags);
+
+	return priv;
+}
+
+
+static struct usb_host_endpoint *get_ep_from_epnum(struct usb_device *udev,
+		int epnum0)
+{
+	struct usb_host_config *config;
+	int i = 0, j = 0;
+	struct usb_host_endpoint *ep = NULL;
+	int epnum;
+	int found = 0;
+
+	if (epnum0 == 0)
+		return &udev->ep0;
+
+	config = udev->actconfig;
+	if (!config)
+		return NULL;
+
+	for (i = 0; i < config->desc.bNumInterfaces; i++) {
+		struct usb_host_interface *setting;
+
+		setting = config->interface[i]->cur_altsetting;
+
+		for (j = 0; j < setting->desc.bNumEndpoints; j++) {
+			ep = &setting->endpoint[j];
+			epnum = (ep->desc.bEndpointAddress & 0x7f);
+
+			if (epnum == epnum0) {
+				/* uinfo("found epnum %d\n", epnum0); */
+				found = 1;
+				break;
+			}
+		}
+	}
+
+	if (found)
+		return ep;
+	else
+		return NULL;
+}
+
+
+static int get_pipe(struct stub_device *sdev, int epnum, int dir)
+{
+	struct usb_device *udev = interface_to_usbdev(sdev->interface);
+	struct usb_host_endpoint *ep;
+	struct usb_endpoint_descriptor *epd = NULL;
+
+	ep = get_ep_from_epnum(udev, epnum);
+	if (!ep) {
+		dev_err(&sdev->interface->dev, "no such endpoint?, %d\n",
+			epnum);
+		BUG();
+	}
+
+	epd = &ep->desc;
+
+
+#if 0
+	/* epnum 0 is always control */
+	if (epnum == 0) {
+		if (dir == USBIP_DIR_OUT)
+			return usb_sndctrlpipe(udev, 0);
+		else
+			return usb_rcvctrlpipe(udev, 0);
+	}
+#endif
+
+	if (usb_endpoint_xfer_control(epd)) {
+		if (dir == USBIP_DIR_OUT)
+			return usb_sndctrlpipe(udev, epnum);
+		else
+			return usb_rcvctrlpipe(udev, epnum);
+	}
+
+	if (usb_endpoint_xfer_bulk(epd)) {
+		if (dir == USBIP_DIR_OUT)
+			return usb_sndbulkpipe(udev, epnum);
+		else
+			return usb_rcvbulkpipe(udev, epnum);
+	}
+
+	if (usb_endpoint_xfer_int(epd)) {
+		if (dir == USBIP_DIR_OUT)
+			return usb_sndintpipe(udev, epnum);
+		else
+			return usb_rcvintpipe(udev, epnum);
+	}
+
+	if (usb_endpoint_xfer_isoc(epd)) {
+		if (dir == USBIP_DIR_OUT)
+			return usb_sndisocpipe(udev, epnum);
+		else
+			return usb_rcvisocpipe(udev, epnum);
+	}
+
+	/* NOT REACHED */
+	dev_err(&sdev->interface->dev, "get pipe, epnum %d\n", epnum);
+	return 0;
+}
+
+static void stub_recv_cmd_submit(struct stub_device *sdev,
+				 struct usbip_header *pdu)
+{
+	int ret;
+	struct stub_priv *priv;
+	struct usbip_device *ud = &sdev->ud;
+	struct usb_device *udev = interface_to_usbdev(sdev->interface);
+	int pipe = get_pipe(sdev, pdu->base.ep, pdu->base.direction);
+
+
+	priv = stub_priv_alloc(sdev, pdu);
+	if (!priv)
+		return;
+
+	/* setup a urb */
+	if (usb_pipeisoc(pipe))
+		priv->urb = usb_alloc_urb(pdu->u.cmd_submit.number_of_packets,
+								GFP_KERNEL);
+	else
+		priv->urb = usb_alloc_urb(0, GFP_KERNEL);
+
+	if (!priv->urb) {
+		dev_err(&sdev->interface->dev, "malloc urb\n");
+		usbip_event_add(ud, SDEV_EVENT_ERROR_MALLOC);
+		return;
+	}
+
+	/* set priv->urb->transfer_buffer */
+	if (pdu->u.cmd_submit.transfer_buffer_length > 0) {
+		priv->urb->transfer_buffer =
+			kzalloc(pdu->u.cmd_submit.transfer_buffer_length,
+								GFP_KERNEL);
+		if (!priv->urb->transfer_buffer) {
+			dev_err(&sdev->interface->dev, "malloc x_buff\n");
+			usbip_event_add(ud, SDEV_EVENT_ERROR_MALLOC);
+			return;
+		}
+	}
+
+	/* set priv->urb->setup_packet */
+	priv->urb->setup_packet = kzalloc(8, GFP_KERNEL);
+	if (!priv->urb->setup_packet) {
+		dev_err(&sdev->interface->dev, "allocate setup_packet\n");
+		usbip_event_add(ud, SDEV_EVENT_ERROR_MALLOC);
+		return;
+	}
+	memcpy(priv->urb->setup_packet, &pdu->u.cmd_submit.setup, 8);
+
+	/* set other members from the base header of pdu */
+	priv->urb->context                = (void *) priv;
+	priv->urb->dev                    = udev;
+	priv->urb->pipe                   = pipe;
+	priv->urb->complete               = stub_complete;
+
+	usbip_pack_pdu(pdu, priv->urb, USBIP_CMD_SUBMIT, 0);
+
+
+	if (usbip_recv_xbuff(ud, priv->urb) < 0)
+		return;
+
+	if (usbip_recv_iso(ud, priv->urb) < 0)
+		return;
+
+	/* no need to submit an intercepted request, but harmless? */
+	tweak_special_requests(priv->urb);
+
+	/* urb is now ready to submit */
+	ret = usb_submit_urb(priv->urb, GFP_KERNEL);
+
+	if (ret == 0)
+		dbg_stub_rx("submit urb ok, seqnum %u\n", pdu->base.seqnum);
+	else {
+		dev_err(&sdev->interface->dev, "submit_urb error, %d\n", ret);
+		usbip_dump_header(pdu);
+		usbip_dump_urb(priv->urb);
+
+		/*
+		 * Pessimistic.
+		 * This connection will be discarded.
+		 */
+		usbip_event_add(ud, SDEV_EVENT_ERROR_SUBMIT);
+	}
+
+	dbg_stub_rx("Leave\n");
+	return;
+}
+
+/* recv a pdu */
+static void stub_rx_pdu(struct usbip_device *ud)
+{
+	int ret;
+	struct usbip_header pdu;
+	struct stub_device *sdev = container_of(ud, struct stub_device, ud);
+	struct device *dev = &sdev->interface->dev;
+
+	dbg_stub_rx("Enter\n");
+
+	memset(&pdu, 0, sizeof(pdu));
+
+	/* 1. receive a pdu header */
+	ret = usbip_xmit(0, ud->tcp_socket, (char *) &pdu, sizeof(pdu), 0);
+	if (ret != sizeof(pdu)) {
+		dev_err(dev, "recv a header, %d\n", ret);
+		usbip_event_add(ud, SDEV_EVENT_ERROR_TCP);
+		return;
+	}
+
+	usbip_header_correct_endian(&pdu, 0);
+
+	if (dbg_flag_stub_rx)
+		usbip_dump_header(&pdu);
+
+	if (!valid_request(sdev, &pdu)) {
+		dev_err(dev, "recv invalid request\n");
+		usbip_event_add(ud, SDEV_EVENT_ERROR_TCP);
+		return;
+	}
+
+	switch (pdu.base.command) {
+	case USBIP_CMD_UNLINK:
+		stub_recv_cmd_unlink(sdev, &pdu);
+		break;
+
+	case USBIP_CMD_SUBMIT:
+		stub_recv_cmd_submit(sdev, &pdu);
+		break;
+
+	default:
+		/* NOTREACHED */
+		dev_err(dev, "unknown pdu\n");
+		usbip_event_add(ud, SDEV_EVENT_ERROR_TCP);
+		return;
+	}
+
+}
+
+void stub_rx_loop(struct usbip_task *ut)
+{
+	struct usbip_device *ud = container_of(ut, struct usbip_device, tcp_rx);
+
+	while (1) {
+		if (signal_pending(current)) {
+			dbg_stub_rx("signal caught!\n");
+			break;
+		}
+
+		if (usbip_event_happend(ud))
+			break;
+
+		stub_rx_pdu(ud);
+	}
+}
diff --git a/drivers/staging/usbip/stub_tx.c b/drivers/staging/usbip/stub_tx.c
new file mode 100644
index 000000000000..d5563cd980be
--- /dev/null
+++ b/drivers/staging/usbip/stub_tx.c
@@ -0,0 +1,371 @@
+/*
+ * 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 "usbip_common.h"
+#include "stub.h"
+
+
+static void stub_free_priv_and_urb(struct stub_priv *priv)
+{
+	struct urb *urb = priv->urb;
+
+	kfree(urb->setup_packet);
+	kfree(urb->transfer_buffer);
+	list_del(&priv->list);
+	kmem_cache_free(stub_priv_cache, priv);
+	usb_free_urb(urb);
+}
+
+/* be in spin_lock_irqsave(&sdev->priv_lock, flags) */
+void stub_enqueue_ret_unlink(struct stub_device *sdev, __u32 seqnum,
+			     __u32 status)
+{
+	struct stub_unlink *unlink;
+
+	unlink = kzalloc(sizeof(struct stub_unlink), GFP_ATOMIC);
+	if (!unlink) {
+		dev_err(&sdev->interface->dev, "alloc stub_unlink\n");
+		usbip_event_add(&sdev->ud, VDEV_EVENT_ERROR_MALLOC);
+		return;
+	}
+
+	unlink->seqnum = seqnum;
+	unlink->status = status;
+
+	list_add_tail(&unlink->list, &sdev->unlink_tx);
+}
+
+/**
+ * stub_complete - completion handler of a usbip urb
+ * @urb: pointer to the urb completed
+ * @regs:
+ *
+ * When a urb has completed, the USB core driver calls this function mostly in
+ * the interrupt context. To return the result of a urb, the completed urb is
+ * linked to the pending list of returning.
+ *
+ */
+void stub_complete(struct urb *urb)
+{
+	struct stub_priv *priv = (struct stub_priv *) urb->context;
+	struct stub_device *sdev = priv->sdev;
+	unsigned long flags;
+
+	dbg_stub_tx("complete! status %d\n", urb->status);
+
+
+	switch (urb->status) {
+	case 0:
+		/* OK */
+		break;
+	case -ENOENT:
+		uinfo("stopped by a call of usb_kill_urb() because of"
+					"cleaning up a virtual connection\n");
+		return;
+	case -ECONNRESET:
+		uinfo("unlinked by a call of usb_unlink_urb()\n");
+		break;
+	case -EPIPE:
+		uinfo("endpoint %d is stalled\n", usb_pipeendpoint(urb->pipe));
+		break;
+	case -ESHUTDOWN:
+		uinfo("device removed?\n");
+		break;
+	default:
+		uinfo("urb completion with non-zero status %d\n", urb->status);
+	}
+
+	/* link a urb to the queue of tx. */
+	spin_lock_irqsave(&sdev->priv_lock, flags);
+
+	if (priv->unlinking) {
+		stub_enqueue_ret_unlink(sdev, priv->seqnum, urb->status);
+		stub_free_priv_and_urb(priv);
+	} else
+		list_move_tail(&priv->list, &sdev->priv_tx);
+
+
+	spin_unlock_irqrestore(&sdev->priv_lock, flags);
+
+	/* wake up tx_thread */
+	wake_up(&sdev->tx_waitq);
+}
+
+
+/*-------------------------------------------------------------------------*/
+/* fill PDU */
+
+static inline void setup_base_pdu(struct usbip_header_basic *base,
+		__u32 command, __u32 seqnum)
+{
+	base->command = command;
+	base->seqnum  = seqnum;
+	base->devid   = 0;
+	base->ep      = 0;
+	base->direction   = 0;
+}
+
+static void setup_ret_submit_pdu(struct usbip_header *rpdu, struct urb *urb)
+{
+	struct stub_priv *priv = (struct stub_priv *) urb->context;
+
+	setup_base_pdu(&rpdu->base, USBIP_RET_SUBMIT, priv->seqnum);
+
+	usbip_pack_pdu(rpdu, urb, USBIP_RET_SUBMIT, 1);
+}
+
+static void setup_ret_unlink_pdu(struct usbip_header *rpdu,
+		struct stub_unlink *unlink)
+{
+	setup_base_pdu(&rpdu->base, USBIP_RET_UNLINK, unlink->seqnum);
+
+	rpdu->u.ret_unlink.status = unlink->status;
+}
+
+
+/*-------------------------------------------------------------------------*/
+/* send RET_SUBMIT */
+
+static struct stub_priv *dequeue_from_priv_tx(struct stub_device *sdev)
+{
+	unsigned long flags;
+	struct stub_priv *priv, *tmp;
+
+	spin_lock_irqsave(&sdev->priv_lock, flags);
+
+	list_for_each_entry_safe(priv, tmp, &sdev->priv_tx, list) {
+		list_move_tail(&priv->list, &sdev->priv_free);
+		spin_unlock_irqrestore(&sdev->priv_lock, flags);
+		return priv;
+	}
+
+	spin_unlock_irqrestore(&sdev->priv_lock, flags);
+
+	return NULL;
+}
+
+static int stub_send_ret_submit(struct stub_device *sdev)
+{
+	unsigned long flags;
+	struct stub_priv *priv, *tmp;
+
+	struct msghdr msg;
+	struct kvec iov[3];
+	size_t txsize;
+
+	size_t total_size = 0;
+
+	while ((priv = dequeue_from_priv_tx(sdev)) != NULL) {
+		int ret;
+		struct urb *urb = priv->urb;
+		struct usbip_header pdu_header;
+		void *iso_buffer = NULL;
+
+		txsize = 0;
+		memset(&pdu_header, 0, sizeof(pdu_header));
+		memset(&msg, 0, sizeof(msg));
+		memset(&iov, 0, sizeof(iov));
+
+		dbg_stub_tx("setup txdata urb %p\n", urb);
+
+
+		/* 1. setup usbip_header */
+		setup_ret_submit_pdu(&pdu_header, urb);
+		usbip_header_correct_endian(&pdu_header, 1);
+
+		iov[0].iov_base = &pdu_header;
+		iov[0].iov_len  = sizeof(pdu_header);
+		txsize += sizeof(pdu_header);
+
+		/* 2. setup transfer buffer */
+		if (usb_pipein(urb->pipe) && urb->actual_length > 0) {
+			iov[1].iov_base = urb->transfer_buffer;
+			iov[1].iov_len  = urb->actual_length;
+			txsize += urb->actual_length;
+		}
+
+		/* 3. setup iso_packet_descriptor */
+		if (usb_pipetype(urb->pipe) == PIPE_ISOCHRONOUS) {
+			ssize_t len = 0;
+
+			iso_buffer = usbip_alloc_iso_desc_pdu(urb, &len);
+			if (!iso_buffer) {
+				usbip_event_add(&sdev->ud,
+						SDEV_EVENT_ERROR_MALLOC);
+				return -1;
+			}
+
+			iov[2].iov_base = iso_buffer;
+			iov[2].iov_len  = len;
+			txsize += len;
+		}
+
+		ret = kernel_sendmsg(sdev->ud.tcp_socket, &msg, iov,
+				     3, txsize);
+		if (ret != txsize) {
+			dev_err(&sdev->interface->dev,
+				"sendmsg failed!, retval %d for %zd\n",
+				ret, txsize);
+			kfree(iso_buffer);
+			usbip_event_add(&sdev->ud, SDEV_EVENT_ERROR_TCP);
+			return -1;
+		}
+
+		kfree(iso_buffer);
+		dbg_stub_tx("send txdata\n");
+
+		total_size += txsize;
+	}
+
+
+	spin_lock_irqsave(&sdev->priv_lock, flags);
+
+	list_for_each_entry_safe(priv, tmp, &sdev->priv_free, list) {
+		stub_free_priv_and_urb(priv);
+	}
+
+	spin_unlock_irqrestore(&sdev->priv_lock, flags);
+
+	return total_size;
+}
+
+
+/*-------------------------------------------------------------------------*/
+/* send RET_UNLINK */
+
+static struct stub_unlink *dequeue_from_unlink_tx(struct stub_device *sdev)
+{
+	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_move_tail(&unlink->list, &sdev->unlink_free);
+		spin_unlock_irqrestore(&sdev->priv_lock, flags);
+		return unlink;
+	}
+
+	spin_unlock_irqrestore(&sdev->priv_lock, flags);
+
+	return NULL;
+}
+
+
+static int stub_send_ret_unlink(struct stub_device *sdev)
+{
+	unsigned long flags;
+	struct stub_unlink *unlink, *tmp;
+
+	struct msghdr msg;
+	struct kvec iov[1];
+	size_t txsize;
+
+	size_t total_size = 0;
+
+	while ((unlink = dequeue_from_unlink_tx(sdev)) != NULL) {
+		int ret;
+		struct usbip_header pdu_header;
+
+		txsize = 0;
+		memset(&pdu_header, 0, sizeof(pdu_header));
+		memset(&msg, 0, sizeof(msg));
+		memset(&iov, 0, sizeof(iov));
+
+		dbg_stub_tx("setup ret unlink %lu\n", unlink->seqnum);
+
+		/* 1. setup usbip_header */
+		setup_ret_unlink_pdu(&pdu_header, unlink);
+		usbip_header_correct_endian(&pdu_header, 1);
+
+		iov[0].iov_base = &pdu_header;
+		iov[0].iov_len  = sizeof(pdu_header);
+		txsize += sizeof(pdu_header);
+
+		ret = kernel_sendmsg(sdev->ud.tcp_socket, &msg, iov,
+				     1, txsize);
+		if (ret != txsize) {
+			dev_err(&sdev->interface->dev,
+				"sendmsg failed!, retval %d for %zd\n",
+				ret, txsize);
+			usbip_event_add(&sdev->ud, SDEV_EVENT_ERROR_TCP);
+			return -1;
+		}
+
+
+		dbg_stub_tx("send txdata\n");
+
+		total_size += txsize;
+	}
+
+
+	spin_lock_irqsave(&sdev->priv_lock, flags);
+
+	list_for_each_entry_safe(unlink, tmp, &sdev->unlink_free, list) {
+		list_del(&unlink->list);
+		kfree(unlink);
+	}
+
+	spin_unlock_irqrestore(&sdev->priv_lock, flags);
+
+	return total_size;
+}
+
+
+/*-------------------------------------------------------------------------*/
+
+void stub_tx_loop(struct usbip_task *ut)
+{
+	struct usbip_device *ud = container_of(ut, struct usbip_device, tcp_tx);
+	struct stub_device *sdev = container_of(ud, struct stub_device, ud);
+
+	while (1) {
+		if (signal_pending(current)) {
+			dbg_stub_tx("signal catched\n");
+			break;
+		}
+
+		if (usbip_event_happend(ud))
+			break;
+
+		/*
+		 * send_ret_submit comes earlier than send_ret_unlink.  stub_rx
+		 * looks at only priv_init queue. If the completion of a URB is
+		 * earlier than the receive of CMD_UNLINK, priv is moved to
+		 * priv_tx queue and stub_rx does not find the target priv. In
+		 * this case, vhci_rx receives the result of the submit request
+		 * and then receives the result of the unlink request. The
+		 * result of the submit is given back to the usbcore as the
+		 * completion of the unlink request. The request of the
+		 * unlink is ignored. This is ok because a driver who calls
+		 * usb_unlink_urb() understands the unlink was too late by
+		 * getting the status of the given-backed URB which has the
+		 * status of usb_submit_urb().
+		 */
+		if (stub_send_ret_submit(sdev) < 0)
+			break;
+
+		if (stub_send_ret_unlink(sdev) < 0)
+			break;
+
+		wait_event_interruptible(sdev->tx_waitq,
+				(!list_empty(&sdev->priv_tx) ||
+				 !list_empty(&sdev->unlink_tx)));
+	}
+}