23 files changed, 8711 insertions, 0 deletions

diff --git a/drivers/usb/usbip/Kconfig b/drivers/usb/usbip/Kconfig
new file mode 100644
index 000000000..8276a20ec
--- /dev/null
+++ b/drivers/usb/usbip/Kconfig
@@ -0,0 +1,75 @@
+config USBIP_CORE
+	tristate "USB/IP support"
+	depends on NET
+	select USB_COMMON
+	select SGL_ALLOC
+	---help---
+	  This enables pushing USB packets over IP to allow remote
+	  machines direct access to USB devices. It provides the
+	  USB/IP core that is required by both drivers.
+
+	  For more details, and to get the userspace utility
+	  programs, please see <http://usbip.sourceforge.net/>.
+
+	  To compile this as a module, choose M here: the module will
+	  be called usbip-core.
+
+	  If unsure, say N.
+
+config USBIP_VHCI_HCD
+	tristate "VHCI hcd"
+	depends on USBIP_CORE && USB
+	---help---
+	  This enables the USB/IP virtual host controller driver,
+	  which is run on the remote machine.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called vhci-hcd.
+
+config USBIP_VHCI_HC_PORTS
+	int "Number of ports per USB/IP virtual host controller"
+	range 1 15
+	default 8
+	depends on USBIP_VHCI_HCD
+	---help---
+	  To increase number of ports available for USB/IP virtual
+	  host controller driver, this defines number of ports per
+	  USB/IP virtual host controller.
+
+config USBIP_VHCI_NR_HCS
+	int "Number of USB/IP virtual host controllers"
+	range 1 128
+	default 1
+	depends on USBIP_VHCI_HCD
+	---help---
+	  To increase number of ports available for USB/IP virtual
+	  host controller driver, this defines number of USB/IP
+	  virtual host controllers as if adding physical host
+	  controllers.
+
+config USBIP_HOST
+	tristate "Host driver"
+	depends on USBIP_CORE && USB
+	---help---
+	  This enables the USB/IP host driver, which is run on the
+	  machine that is sharing the USB devices.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called usbip-host.
+
+config USBIP_VUDC
+	tristate "VUDC driver"
+	depends on USBIP_CORE && USB_GADGET
+	---help---
+	  This enables the USB/IP virtual USB device controller
+	  driver, which is run on the host machine, allowing the
+	  machine itself to act as a device.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called usbip-vudc.
+
+config USBIP_DEBUG
+	bool "Debug messages for USB/IP"
+	depends on USBIP_CORE
+	---help---
+	  This enables the debug messages from the USB/IP drivers.
diff --git a/drivers/usb/usbip/Makefile b/drivers/usb/usbip/Makefile
new file mode 100644
index 000000000..f4c8f3840
--- /dev/null
+++ b/drivers/usb/usbip/Makefile
@@ -0,0 +1,14 @@
+# SPDX-License-Identifier: GPL-2.0
+ccflags-$(CONFIG_USBIP_DEBUG) := -DDEBUG
+
+obj-$(CONFIG_USBIP_CORE) += usbip-core.o
+usbip-core-y := usbip_common.o usbip_event.o
+
+obj-$(CONFIG_USBIP_VHCI_HCD) += vhci-hcd.o
+vhci-hcd-y := vhci_sysfs.o vhci_tx.o vhci_rx.o vhci_hcd.o
+
+obj-$(CONFIG_USBIP_HOST) += usbip-host.o
+usbip-host-y := stub_dev.o stub_main.o stub_rx.o stub_tx.o
+
+obj-$(CONFIG_USBIP_VUDC) += usbip-vudc.o
+usbip-vudc-y := vudc_dev.o vudc_sysfs.o vudc_tx.o vudc_rx.o vudc_transfer.o vudc_main.o
diff --git a/drivers/usb/usbip/README b/drivers/usb/usbip/README
new file mode 100644
index 000000000..41a2cf2e7
--- /dev/null
+++ b/drivers/usb/usbip/README
@@ -0,0 +1,7 @@
+TODO:
+	- more discussion about the protocol
+	- testing
+	- review of the userspace interface
+	- document the protocol
+
+Please send patches for this code to Greg Kroah-Hartman <greg@kroah.com>
diff --git a/drivers/usb/usbip/stub.h b/drivers/usb/usbip/stub.h
new file mode 100644
index 000000000..d11270560
--- /dev/null
+++ b/drivers/usb/usbip/stub.h
@@ -0,0 +1,105 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (C) 2003-2008 Takahiro Hirofuchi
+ */
+
+#ifndef __USBIP_STUB_H
+#define __USBIP_STUB_H
+
+#include <linux/list.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+#include <linux/types.h>
+#include <linux/usb.h>
+#include <linux/wait.h>
+
+#define STUB_BUSID_OTHER 0
+#define STUB_BUSID_REMOV 1
+#define STUB_BUSID_ADDED 2
+#define STUB_BUSID_ALLOC 3
+
+struct stub_device {
+	struct usb_device *udev;
+
+	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 **urbs;
+	struct scatterlist *sgl;
+	int num_urbs;
+	int completed_urbs;
+	int urb_status;
+
+	int unlinking;
+};
+
+struct stub_unlink {
+	unsigned long seqnum;
+	struct list_head list;
+	__u32 status;
+};
+
+/* same as SYSFS_BUS_ID_SIZE */
+#define BUSID_SIZE 32
+
+struct bus_id_priv {
+	char name[BUSID_SIZE];
+	char status;
+	int interf_count;
+	struct stub_device *sdev;
+	struct usb_device *udev;
+	char shutdown_busid;
+	spinlock_t busid_lock;
+};
+
+/* stub_priv is allocated from stub_priv_cache */
+extern struct kmem_cache *stub_priv_cache;
+
+/* stub_dev.c */
+extern struct usb_device_driver stub_driver;
+
+/* stub_main.c */
+struct bus_id_priv *get_busid_priv(const char *busid);
+void put_busid_priv(struct bus_id_priv *bid);
+int del_match_busid(char *busid);
+void stub_free_priv_and_urb(struct stub_priv *priv);
+void stub_device_cleanup_urbs(struct stub_device *sdev);
+
+/* stub_rx.c */
+int stub_rx_loop(void *data);
+
+/* stub_tx.c */
+void stub_enqueue_ret_unlink(struct stub_device *sdev, __u32 seqnum,
+			     __u32 status);
+void stub_complete(struct urb *urb);
+int stub_tx_loop(void *data);
+
+#endif /* __USBIP_STUB_H */
diff --git a/drivers/usb/usbip/stub_dev.c b/drivers/usb/usbip/stub_dev.c
new file mode 100644
index 000000000..c64964c32
--- /dev/null
+++ b/drivers/usb/usbip/stub_dev.c
@@ -0,0 +1,564 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (C) 2003-2008 Takahiro Hirofuchi
+ */
+
+#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 usbip_sockfd_store(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;
+	struct task_struct *tcp_rx = NULL;
+	struct task_struct *tcp_tx = NULL;
+
+	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");
+
+		mutex_lock(&sdev->ud.sysfs_lock);
+		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) {
+			dev_err(dev, "failed to lookup sock");
+			goto err;
+		}
+
+		if (socket->type != SOCK_STREAM) {
+			dev_err(dev, "Expecting SOCK_STREAM - found %d",
+				socket->type);
+			goto sock_err;
+		}
+
+		/* unlock and create threads and get tasks */
+		spin_unlock_irq(&sdev->ud.lock);
+		tcp_rx = kthread_create(stub_rx_loop, &sdev->ud, "stub_rx");
+		if (IS_ERR(tcp_rx)) {
+			sockfd_put(socket);
+			goto unlock_mutex;
+		}
+		tcp_tx = kthread_create(stub_tx_loop, &sdev->ud, "stub_tx");
+		if (IS_ERR(tcp_tx)) {
+			kthread_stop(tcp_rx);
+			sockfd_put(socket);
+			goto unlock_mutex;
+		}
+
+		/* get task structs now */
+		get_task_struct(tcp_rx);
+		get_task_struct(tcp_tx);
+
+		/* lock and update sdev->ud state */
+		spin_lock_irq(&sdev->ud.lock);
+		sdev->ud.tcp_socket = socket;
+		sdev->ud.sockfd = sockfd;
+		sdev->ud.tcp_rx = tcp_rx;
+		sdev->ud.tcp_tx = tcp_tx;
+		sdev->ud.status = SDEV_ST_USED;
+		spin_unlock_irq(&sdev->ud.lock);
+
+		wake_up_process(sdev->ud.tcp_rx);
+		wake_up_process(sdev->ud.tcp_tx);
+
+		mutex_unlock(&sdev->ud.sysfs_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);
+		mutex_unlock(&sdev->ud.sysfs_lock);
+	}
+
+	return count;
+
+sock_err:
+	sockfd_put(socket);
+err:
+	spin_unlock_irq(&sdev->ud.lock);
+unlock_mutex:
+	mutex_unlock(&sdev->ud.sysfs_lock);
+	return -EINVAL;
+}
+static DEVICE_ATTR_WO(usbip_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, NULL);
+	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
+ * @udev: usb_device 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);
+	mutex_init(&sdev->ud.sysfs_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;
+	char save_status;
+
+	dev_dbg(&udev->dev, "Enter probe\n");
+
+	/* Not sure if this is our device. Allocate here to avoid
+	 * calling alloc while holding busid_table lock.
+	 */
+	sdev = stub_device_alloc(udev);
+	if (!sdev)
+		return -ENOMEM;
+
+	/* 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;
+		if (!busid_priv)
+			goto sdev_free;
+
+		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;
+	}
+
+
+	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;
+
+	save_status = busid_priv->status;
+	busid_priv->status = STUB_BUSID_ALLOC;
+
+	/* release the busid_lock */
+	put_busid_priv(busid_priv);
+
+	/*
+	 * 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;
+	}
+
+	return 0;
+
+err_files:
+	usb_hub_release_port(udev->parent, udev->portnum,
+			     (struct usb_dev_state *) udev);
+err_port:
+	dev_set_drvdata(&udev->dev, NULL);
+
+	/* we already have busid_priv, just lock busid_lock */
+	spin_lock(&busid_priv->busid_lock);
+	busid_priv->sdev = NULL;
+	busid_priv->status = save_status;
+	spin_unlock(&busid_priv->busid_lock);
+	/* lock is released - go to free */
+	goto sdev_free;
+
+call_put_busid_priv:
+	/* release the busid_lock */
+	put_busid_priv(busid_priv);
+
+sdev_free:
+	usb_put_dev(udev);
+	stub_device_free(sdev);
+
+	return rc;
+}
+
+static void shutdown_busid(struct bus_id_priv *busid_priv)
+{
+	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");
+		/* release busid_lock */
+		put_busid_priv(busid_priv);
+		return;
+	}
+
+	dev_set_drvdata(&udev->dev, NULL);
+
+	/* release busid_lock before call to remove device files */
+	put_busid_priv(busid_priv);
+
+	/*
+	 * 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");
+		return;
+	}
+
+	/* If usb reset is called from event handler */
+	if (usbip_in_eh(current))
+		return;
+
+	/* we already have busid_priv, just lock busid_lock */
+	spin_lock(&busid_priv->busid_lock);
+	if (!busid_priv->shutdown_busid)
+		busid_priv->shutdown_busid = 1;
+	/* release busid_lock */
+	spin_unlock(&busid_priv->busid_lock);
+
+	/* shutdown the current connection */
+	shutdown_busid(busid_priv);
+
+	usb_put_dev(sdev->udev);
+
+	/* we already have busid_priv, just lock busid_lock */
+	spin_lock(&busid_priv->busid_lock);
+	/* free sdev */
+	busid_priv->sdev = NULL;
+	stub_device_free(sdev);
+
+	if (busid_priv->status == STUB_BUSID_ALLOC)
+		busid_priv->status = STUB_BUSID_ADDED;
+	/* release busid_lock */
+	spin_unlock(&busid_priv->busid_lock);
+	return;
+}
+
+#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,
+};
diff --git a/drivers/usb/usbip/stub_main.c b/drivers/usb/usbip/stub_main.c
new file mode 100644
index 000000000..a20bb2d04
--- /dev/null
+++ b/drivers/usb/usbip/stub_main.c
@@ -0,0 +1,434 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (C) 2003-2008 Takahiro Hirofuchi
+ */
+
+#include <linux/string.h>
+#include <linux/module.h>
+#include <linux/device.h>
+#include <linux/scatterlist.h>
+
+#include "usbip_common.h"
+#include "stub.h"
+
+#define DRIVER_AUTHOR "Takahiro Hirofuchi"
+#define DRIVER_DESC "USB/IP Host Driver"
+
+struct kmem_cache *stub_priv_cache;
+
+/*
+ * 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 struct bus_id_priv busid_table[MAX_BUSID];
+static spinlock_t busid_table_lock;
+
+static void init_busid_table(void)
+{
+	int i;
+
+	/*
+	 * This also sets the bus_table[i].status to
+	 * STUB_BUSID_OTHER, which is 0.
+	 */
+	memset(busid_table, 0, sizeof(busid_table));
+
+	spin_lock_init(&busid_table_lock);
+
+	for (i = 0; i < MAX_BUSID; i++)
+		spin_lock_init(&busid_table[i].busid_lock);
+}
+
+/*
+ * Find the index of the busid by name.
+ * Must be called with busid_table_lock held.
+ */
+static int get_busid_idx(const char *busid)
+{
+	int i;
+	int idx = -1;
+
+	for (i = 0; i < MAX_BUSID; i++) {
+		spin_lock(&busid_table[i].busid_lock);
+		if (busid_table[i].name[0])
+			if (!strncmp(busid_table[i].name, busid, BUSID_SIZE)) {
+				idx = i;
+				spin_unlock(&busid_table[i].busid_lock);
+				break;
+			}
+		spin_unlock(&busid_table[i].busid_lock);
+	}
+	return idx;
+}
+
+/* Returns holding busid_lock. Should call put_busid_priv() to unlock */
+struct bus_id_priv *get_busid_priv(const char *busid)
+{
+	int idx;
+	struct bus_id_priv *bid = NULL;
+
+	spin_lock(&busid_table_lock);
+	idx = get_busid_idx(busid);
+	if (idx >= 0) {
+		bid = &(busid_table[idx]);
+		/* get busid_lock before returning */
+		spin_lock(&bid->busid_lock);
+	}
+	spin_unlock(&busid_table_lock);
+
+	return bid;
+}
+
+void put_busid_priv(struct bus_id_priv *bid)
+{
+	if (bid)
+		spin_unlock(&bid->busid_lock);
+}
+
+static int add_match_busid(char *busid)
+{
+	int i;
+	int ret = -1;
+
+	spin_lock(&busid_table_lock);
+	/* already registered? */
+	if (get_busid_idx(busid) >= 0) {
+		ret = 0;
+		goto out;
+	}
+
+	for (i = 0; i < MAX_BUSID; i++) {
+		spin_lock(&busid_table[i].busid_lock);
+		if (!busid_table[i].name[0]) {
+			strlcpy(busid_table[i].name, busid, BUSID_SIZE);
+			if ((busid_table[i].status != STUB_BUSID_ALLOC) &&
+			    (busid_table[i].status != STUB_BUSID_REMOV))
+				busid_table[i].status = STUB_BUSID_ADDED;
+			ret = 0;
+			spin_unlock(&busid_table[i].busid_lock);
+			break;
+		}
+		spin_unlock(&busid_table[i].busid_lock);
+	}
+
+out:
+	spin_unlock(&busid_table_lock);
+
+	return ret;
+}
+
+int del_match_busid(char *busid)
+{
+	int idx;
+	int ret = -1;
+
+	spin_lock(&busid_table_lock);
+	idx = get_busid_idx(busid);
+	if (idx < 0)
+		goto out;
+
+	/* found */
+	ret = 0;
+
+	spin_lock(&busid_table[idx].busid_lock);
+
+	if (busid_table[idx].status == STUB_BUSID_OTHER)
+		memset(busid_table[idx].name, 0, BUSID_SIZE);
+
+	if ((busid_table[idx].status != STUB_BUSID_OTHER) &&
+	    (busid_table[idx].status != STUB_BUSID_ADDED))
+		busid_table[idx].status = STUB_BUSID_REMOV;
+
+	spin_unlock(&busid_table[idx].busid_lock);
+out:
+	spin_unlock(&busid_table_lock);
+
+	return ret;
+}
+
+static ssize_t match_busid_show(struct device_driver *drv, char *buf)
+{
+	int i;
+	char *out = buf;
+
+	spin_lock(&busid_table_lock);
+	for (i = 0; i < MAX_BUSID; i++) {
+		spin_lock(&busid_table[i].busid_lock);
+		if (busid_table[i].name[0])
+			out += sprintf(out, "%s ", busid_table[i].name);
+		spin_unlock(&busid_table[i].busid_lock);
+	}
+	spin_unlock(&busid_table_lock);
+	out += sprintf(out, "\n");
+
+	return out - buf;
+}
+
+static ssize_t match_busid_store(struct device_driver *dev, const char *buf,
+				 size_t count)
+{
+	int len;
+	char busid[BUSID_SIZE];
+
+	if (count < 5)
+		return -EINVAL;
+
+	/* busid needs to include \0 termination */
+	len = strlcpy(busid, buf + 4, BUSID_SIZE);
+	if (sizeof(busid) <= len)
+		return -EINVAL;
+
+	if (!strncmp(buf, "add ", 4)) {
+		if (add_match_busid(busid) < 0)
+			return -ENOMEM;
+
+		pr_debug("add busid %s\n", busid);
+		return count;
+	}
+
+	if (!strncmp(buf, "del ", 4)) {
+		if (del_match_busid(busid) < 0)
+			return -ENODEV;
+
+		pr_debug("del busid %s\n", busid);
+		return count;
+	}
+
+	return -EINVAL;
+}
+static DRIVER_ATTR_RW(match_busid);
+
+static int do_rebind(char *busid, struct bus_id_priv *busid_priv)
+{
+	int ret;
+
+	/* device_attach() callers should hold parent lock for USB */
+	if (busid_priv->udev->dev.parent)
+		device_lock(busid_priv->udev->dev.parent);
+	ret = device_attach(&busid_priv->udev->dev);
+	if (busid_priv->udev->dev.parent)
+		device_unlock(busid_priv->udev->dev.parent);
+	if (ret < 0) {
+		dev_err(&busid_priv->udev->dev, "rebind failed\n");
+		return ret;
+	}
+	return 0;
+}
+
+static void stub_device_rebind(void)
+{
+#if IS_MODULE(CONFIG_USBIP_HOST)
+	struct bus_id_priv *busid_priv;
+	int i;
+
+	/* update status to STUB_BUSID_OTHER so probe ignores the device */
+	spin_lock(&busid_table_lock);
+	for (i = 0; i < MAX_BUSID; i++) {
+		if (busid_table[i].name[0] &&
+		    busid_table[i].shutdown_busid) {
+			busid_priv = &(busid_table[i]);
+			busid_priv->status = STUB_BUSID_OTHER;
+		}
+	}
+	spin_unlock(&busid_table_lock);
+
+	/* now run rebind - no need to hold locks. driver files are removed */
+	for (i = 0; i < MAX_BUSID; i++) {
+		if (busid_table[i].name[0] &&
+		    busid_table[i].shutdown_busid) {
+			busid_priv = &(busid_table[i]);
+			do_rebind(busid_table[i].name, busid_priv);
+		}
+	}
+#endif
+}
+
+static ssize_t rebind_store(struct device_driver *dev, const char *buf,
+				 size_t count)
+{
+	int ret;
+	int len;
+	struct bus_id_priv *bid;
+
+	/* buf length should be less that BUSID_SIZE */
+	len = strnlen(buf, BUSID_SIZE);
+
+	if (!(len < BUSID_SIZE))
+		return -EINVAL;
+
+	bid = get_busid_priv(buf);
+	if (!bid)
+		return -ENODEV;
+
+	/* mark the device for deletion so probe ignores it during rescan */
+	bid->status = STUB_BUSID_OTHER;
+	/* release the busid lock */
+	put_busid_priv(bid);
+
+	ret = do_rebind((char *) buf, bid);
+	if (ret < 0)
+		return ret;
+
+	/* delete device from busid_table */
+	del_match_busid((char *) buf);
+
+	return count;
+}
+
+static DRIVER_ATTR_WO(rebind);
+
+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_init(&priv->list);
+		return priv;
+	}
+
+	return NULL;
+}
+
+void stub_free_priv_and_urb(struct stub_priv *priv)
+{
+	struct urb *urb;
+	int i;
+
+	for (i = 0; i < priv->num_urbs; i++) {
+		urb = priv->urbs[i];
+
+		if (!urb)
+			return;
+
+		kfree(urb->setup_packet);
+		urb->setup_packet = NULL;
+
+
+		if (urb->transfer_buffer && !priv->sgl) {
+			kfree(urb->transfer_buffer);
+			urb->transfer_buffer = NULL;
+		}
+
+		if (urb->num_sgs) {
+			sgl_free(urb->sg);
+			urb->sg = NULL;
+			urb->num_sgs = 0;
+		}
+
+		usb_free_urb(urb);
+	}
+	if (!list_empty(&priv->list))
+		list_del(&priv->list);
+	if (priv->sgl)
+		sgl_free(priv->sgl);
+	kfree(priv->urbs);
+	kmem_cache_free(stub_priv_cache, priv);
+}
+
+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)
+		goto done;
+
+	priv = stub_priv_pop_from_listhead(&sdev->priv_tx);
+	if (priv)
+		goto done;
+
+	priv = stub_priv_pop_from_listhead(&sdev->priv_free);
+
+done:
+	spin_unlock_irqrestore(&sdev->priv_lock, flags);
+
+	return priv;
+}
+
+void stub_device_cleanup_urbs(struct stub_device *sdev)
+{
+	struct stub_priv *priv;
+	int i;
+
+	dev_dbg(&sdev->udev->dev, "Stub device cleaning up urbs\n");
+
+	while ((priv = stub_priv_pop(sdev))) {
+		for (i = 0; i < priv->num_urbs; i++)
+			usb_kill_urb(priv->urbs[i]);
+
+		stub_free_priv_and_urb(priv);
+	}
+}
+
+static int __init usbip_host_init(void)
+{
+	int ret;
+
+	init_busid_table();
+
+	stub_priv_cache = KMEM_CACHE(stub_priv, SLAB_HWCACHE_ALIGN);
+	if (!stub_priv_cache) {
+		pr_err("kmem_cache_create failed\n");
+		return -ENOMEM;
+	}
+
+	ret = usb_register_device_driver(&stub_driver, THIS_MODULE);
+	if (ret) {
+		pr_err("usb_register failed %d\n", ret);
+		goto err_usb_register;
+	}
+
+	ret = driver_create_file(&stub_driver.drvwrap.driver,
+				 &driver_attr_match_busid);
+	if (ret) {
+		pr_err("driver_create_file failed\n");
+		goto err_create_file;
+	}
+
+	ret = driver_create_file(&stub_driver.drvwrap.driver,
+				 &driver_attr_rebind);
+	if (ret) {
+		pr_err("driver_create_file failed\n");
+		goto err_create_file;
+	}
+
+	return ret;
+
+err_create_file:
+	usb_deregister_device_driver(&stub_driver);
+err_usb_register:
+	kmem_cache_destroy(stub_priv_cache);
+	return ret;
+}
+
+static void __exit usbip_host_exit(void)
+{
+	driver_remove_file(&stub_driver.drvwrap.driver,
+			   &driver_attr_match_busid);
+
+	driver_remove_file(&stub_driver.drvwrap.driver,
+			   &driver_attr_rebind);
+
+	/*
+	 * deregister() calls stub_disconnect() for all devices. Device
+	 * specific data is cleared in stub_disconnect().
+	 */
+	usb_deregister_device_driver(&stub_driver);
+
+	/* initiate scan to attach devices */
+	stub_device_rebind();
+
+	kmem_cache_destroy(stub_priv_cache);
+}
+
+module_init(usbip_host_init);
+module_exit(usbip_host_exit);
+
+MODULE_AUTHOR(DRIVER_AUTHOR);
+MODULE_DESCRIPTION(DRIVER_DESC);
+MODULE_LICENSE("GPL");
diff --git a/drivers/usb/usbip/stub_rx.c b/drivers/usb/usbip/stub_rx.c
new file mode 100644
index 000000000..b88eeaee6
--- /dev/null
+++ b/drivers/usb/usbip/stub_rx.c
@@ -0,0 +1,688 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (C) 2003-2008 Takahiro Hirofuchi
+ */
+
+#include <asm/byteorder.h>
+#include <linux/kthread.h>
+#include <linux/usb.h>
+#include <linux/usb/hcd.h>
+#include <linux/scatterlist.h>
+
+#include "usbip_common.h"
+#include "stub.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)) {
+		usbip_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)
+		dev_err(&urb->dev->dev,
+			"usb_clear_halt error: devnum %d endp %d ret %d\n",
+			urb->dev->devnum, target_endp, ret);
+	else
+		dev_info(&urb->dev->dev,
+			 "usb_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);
+
+	usbip_dbg_stub_rx("set_interface: inf %u alt %u\n",
+			  interface, alternate);
+
+	ret = usb_set_interface(urb->dev, interface, alternate);
+	if (ret < 0)
+		dev_err(&urb->dev->dev,
+			"usb_set_interface error: inf %u alt %u ret %d\n",
+			interface, alternate, ret);
+	else
+		dev_info(&urb->dev->dev,
+			"usb_set_interface done: inf %u alt %u\n",
+			interface, alternate);
+
+	return ret;
+}
+
+static int tweak_set_configuration_cmd(struct urb *urb)
+{
+	struct stub_priv *priv = (struct stub_priv *) urb->context;
+	struct stub_device *sdev = priv->sdev;
+	struct usb_ctrlrequest *req;
+	__u16 config;
+	int err;
+
+	req = (struct usb_ctrlrequest *) urb->setup_packet;
+	config = le16_to_cpu(req->wValue);
+
+	usb_lock_device(sdev->udev);
+	err = usb_set_configuration(sdev->udev, config);
+	usb_unlock_device(sdev->udev);
+	if (err && err != -ENODEV)
+		dev_err(&sdev->udev->dev, "can't set config #%d, error %d\n",
+			config, err);
+	return 0;
+}
+
+static int tweak_reset_device_cmd(struct urb *urb)
+{
+	struct stub_priv *priv = (struct stub_priv *) urb->context;
+	struct stub_device *sdev = priv->sdev;
+
+	dev_info(&urb->dev->dev, "usb_queue_reset_device\n");
+
+	if (usb_lock_device_for_reset(sdev->udev, NULL) < 0) {
+		dev_err(&urb->dev->dev, "could not obtain lock to reset device\n");
+		return 0;
+	}
+	usb_reset_device(sdev->udev);
+	usb_unlock_device(sdev->udev);
+
+	return 0;
+}
+
+/*
+ * 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
+		usbip_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)
+{
+	int ret, i;
+	unsigned long flags;
+	struct stub_priv *priv;
+
+	spin_lock_irqsave(&sdev->priv_lock, flags);
+
+	list_for_each_entry(priv, &sdev->priv_init, list) {
+		if (priv->seqnum != pdu->u.cmd_unlink.seqnum)
+			continue;
+
+		/*
+		 * 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 ?
+		 */
+		for (i = priv->completed_urbs; i < priv->num_urbs; i++) {
+			ret = usb_unlink_urb(priv->urbs[i]);
+			if (ret != -EINPROGRESS)
+				dev_err(&priv->urbs[i]->dev->dev,
+					"failed to unlink %d/%d urb of seqnum %lu, ret %d\n",
+					i + 1, priv->num_urbs,
+					priv->seqnum, ret);
+		}
+		return 0;
+	}
+
+	usbip_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;
+	int valid = 0;
+
+	if (pdu->base.devid == sdev->devid) {
+		spin_lock_irq(&ud->lock);
+		if (ud->status == SDEV_ST_USED) {
+			/* A request is valid. */
+			valid = 1;
+		}
+		spin_unlock_irq(&ud->lock);
+	}
+
+	return valid;
+}
+
+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_zalloc(stub_priv_cache, GFP_ATOMIC);
+	if (!priv) {
+		dev_err(&sdev->udev->dev, "alloc stub_priv\n");
+		spin_unlock_irqrestore(&sdev->priv_lock, flags);
+		usbip_event_add(ud, SDEV_EVENT_ERROR_MALLOC);
+		return NULL;
+	}
+
+	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 int get_pipe(struct stub_device *sdev, struct usbip_header *pdu)
+{
+	struct usb_device *udev = sdev->udev;
+	struct usb_host_endpoint *ep;
+	struct usb_endpoint_descriptor *epd = NULL;
+	int epnum = pdu->base.ep;
+	int dir = pdu->base.direction;
+
+	if (epnum < 0 || epnum > 15)
+		goto err_ret;
+
+	if (dir == USBIP_DIR_IN)
+		ep = udev->ep_in[epnum & 0x7f];
+	else
+		ep = udev->ep_out[epnum & 0x7f];
+	if (!ep)
+		goto err_ret;
+
+	epd = &ep->desc;
+
+	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)) {
+		/* validate number of packets */
+		if (pdu->u.cmd_submit.number_of_packets < 0 ||
+		    pdu->u.cmd_submit.number_of_packets >
+		    USBIP_MAX_ISO_PACKETS) {
+			dev_err(&sdev->udev->dev,
+				"CMD_SUBMIT: isoc invalid num packets %d\n",
+				pdu->u.cmd_submit.number_of_packets);
+			return -1;
+		}
+		if (dir == USBIP_DIR_OUT)
+			return usb_sndisocpipe(udev, epnum);
+		else
+			return usb_rcvisocpipe(udev, epnum);
+	}
+
+err_ret:
+	/* NOT REACHED */
+	dev_err(&sdev->udev->dev, "CMD_SUBMIT: invalid epnum %d\n", epnum);
+	return -1;
+}
+
+static void masking_bogus_flags(struct urb *urb)
+{
+	int				xfertype;
+	struct usb_device		*dev;
+	struct usb_host_endpoint	*ep;
+	int				is_out;
+	unsigned int	allowed;
+
+	if (!urb || urb->hcpriv || !urb->complete)
+		return;
+	dev = urb->dev;
+	if ((!dev) || (dev->state < USB_STATE_UNAUTHENTICATED))
+		return;
+
+	ep = (usb_pipein(urb->pipe) ? dev->ep_in : dev->ep_out)
+		[usb_pipeendpoint(urb->pipe)];
+	if (!ep)
+		return;
+
+	xfertype = usb_endpoint_type(&ep->desc);
+	if (xfertype == USB_ENDPOINT_XFER_CONTROL) {
+		struct usb_ctrlrequest *setup =
+			(struct usb_ctrlrequest *) urb->setup_packet;
+
+		if (!setup)
+			return;
+		is_out = !(setup->bRequestType & USB_DIR_IN) ||
+			!setup->wLength;
+	} else {
+		is_out = usb_endpoint_dir_out(&ep->desc);
+	}
+
+	/* enforce simple/standard policy */
+	allowed = (URB_NO_TRANSFER_DMA_MAP | URB_NO_INTERRUPT |
+		   URB_DIR_MASK | URB_FREE_BUFFER);
+	switch (xfertype) {
+	case USB_ENDPOINT_XFER_BULK:
+		if (is_out)
+			allowed |= URB_ZERO_PACKET;
+		/* FALLTHROUGH */
+	default:			/* all non-iso endpoints */
+		if (!is_out)
+			allowed |= URB_SHORT_NOT_OK;
+		break;
+	case USB_ENDPOINT_XFER_ISOC:
+		allowed |= URB_ISO_ASAP;
+		break;
+	}
+	urb->transfer_flags &= allowed;
+}
+
+static int stub_recv_xbuff(struct usbip_device *ud, struct stub_priv *priv)
+{
+	int ret;
+	int i;
+
+	for (i = 0; i < priv->num_urbs; i++) {
+		ret = usbip_recv_xbuff(ud, priv->urbs[i]);
+		if (ret < 0)
+			break;
+	}
+
+	return ret;
+}
+
+static void stub_recv_cmd_submit(struct stub_device *sdev,
+				 struct usbip_header *pdu)
+{
+	struct stub_priv *priv;
+	struct usbip_device *ud = &sdev->ud;
+	struct usb_device *udev = sdev->udev;
+	struct scatterlist *sgl = NULL, *sg;
+	void *buffer = NULL;
+	unsigned long long buf_len;
+	int nents;
+	int num_urbs = 1;
+	int pipe = get_pipe(sdev, pdu);
+	int use_sg = pdu->u.cmd_submit.transfer_flags & URB_DMA_MAP_SG;
+	int support_sg = 1;
+	int np = 0;
+	int ret, i;
+
+	if (pipe == -1)
+		return;
+
+	/*
+	 * Smatch reported the error case where use_sg is true and buf_len is 0.
+	 * In this case, It adds SDEV_EVENT_ERROR_MALLOC and stub_priv will be
+	 * released by stub event handler and connection will be shut down.
+	 */
+	priv = stub_priv_alloc(sdev, pdu);
+	if (!priv)
+		return;
+
+	buf_len = (unsigned long long)pdu->u.cmd_submit.transfer_buffer_length;
+
+	if (use_sg && !buf_len) {
+		dev_err(&udev->dev, "sg buffer with zero length\n");
+		goto err_malloc;
+	}
+
+	/* allocate urb transfer buffer, if needed */
+	if (buf_len) {
+		if (use_sg) {
+			sgl = sgl_alloc(buf_len, GFP_KERNEL, &nents);
+			if (!sgl)
+				goto err_malloc;
+
+			/* Check if the server's HCD supports SG */
+			if (!udev->bus->sg_tablesize) {
+				/*
+				 * If the server's HCD doesn't support SG, break
+				 * a single SG request into several URBs and map
+				 * each SG list entry to corresponding URB
+				 * buffer. The previously allocated SG list is
+				 * stored in priv->sgl (If the server's HCD
+				 * support SG, SG list is stored only in
+				 * urb->sg) and it is used as an indicator that
+				 * the server split single SG request into
+				 * several URBs. Later, priv->sgl is used by
+				 * stub_complete() and stub_send_ret_submit() to
+				 * reassemble the divied URBs.
+				 */
+				support_sg = 0;
+				num_urbs = nents;
+				priv->completed_urbs = 0;
+				pdu->u.cmd_submit.transfer_flags &=
+								~URB_DMA_MAP_SG;
+			}
+		} else {
+			buffer = kzalloc(buf_len, GFP_KERNEL);
+			if (!buffer)
+				goto err_malloc;
+		}
+	}
+
+	/* allocate urb array */
+	priv->num_urbs = num_urbs;
+	priv->urbs = kmalloc_array(num_urbs, sizeof(*priv->urbs), GFP_KERNEL);
+	if (!priv->urbs)
+		goto err_urbs;
+
+	/* setup a urb */
+	if (support_sg) {
+		if (usb_pipeisoc(pipe))
+			np = pdu->u.cmd_submit.number_of_packets;
+
+		priv->urbs[0] = usb_alloc_urb(np, GFP_KERNEL);
+		if (!priv->urbs[0])
+			goto err_urb;
+
+		if (buf_len) {
+			if (use_sg) {
+				priv->urbs[0]->sg = sgl;
+				priv->urbs[0]->num_sgs = nents;
+				priv->urbs[0]->transfer_buffer = NULL;
+			} else {
+				priv->urbs[0]->transfer_buffer = buffer;
+			}
+		}
+
+		/* copy urb setup packet */
+		priv->urbs[0]->setup_packet = kmemdup(&pdu->u.cmd_submit.setup,
+					8, GFP_KERNEL);
+		if (!priv->urbs[0]->setup_packet) {
+			usbip_event_add(ud, SDEV_EVENT_ERROR_MALLOC);
+			return;
+		}
+
+		usbip_pack_pdu(pdu, priv->urbs[0], USBIP_CMD_SUBMIT, 0);
+	} else {
+		for_each_sg(sgl, sg, nents, i) {
+			priv->urbs[i] = usb_alloc_urb(0, GFP_KERNEL);
+			/* The URBs which is previously allocated will be freed
+			 * in stub_device_cleanup_urbs() if error occurs.
+			 */
+			if (!priv->urbs[i])
+				goto err_urb;
+
+			usbip_pack_pdu(pdu, priv->urbs[i], USBIP_CMD_SUBMIT, 0);
+			priv->urbs[i]->transfer_buffer = sg_virt(sg);
+			priv->urbs[i]->transfer_buffer_length = sg->length;
+		}
+		priv->sgl = sgl;
+	}
+
+	for (i = 0; i < num_urbs; i++) {
+		/* set other members from the base header of pdu */
+		priv->urbs[i]->context = (void *) priv;
+		priv->urbs[i]->dev = udev;
+		priv->urbs[i]->pipe = pipe;
+		priv->urbs[i]->complete = stub_complete;
+
+		/* no need to submit an intercepted request, but harmless? */
+		tweak_special_requests(priv->urbs[i]);
+
+		masking_bogus_flags(priv->urbs[i]);
+	}
+
+	if (stub_recv_xbuff(ud, priv) < 0)
+		return;
+
+	if (usbip_recv_iso(ud, priv->urbs[0]) < 0)
+		return;
+
+	/* urb is now ready to submit */
+	for (i = 0; i < priv->num_urbs; i++) {
+		ret = usb_submit_urb(priv->urbs[i], GFP_KERNEL);
+
+		if (ret == 0)
+			usbip_dbg_stub_rx("submit urb ok, seqnum %u\n",
+					pdu->base.seqnum);
+		else {
+			dev_err(&udev->dev, "submit_urb error, %d\n", ret);
+			usbip_dump_header(pdu);
+			usbip_dump_urb(priv->urbs[i]);
+
+			/*
+			 * Pessimistic.
+			 * This connection will be discarded.
+			 */
+			usbip_event_add(ud, SDEV_EVENT_ERROR_SUBMIT);
+			break;
+		}
+	}
+
+	usbip_dbg_stub_rx("Leave\n");
+	return;
+
+err_urb:
+	kfree(priv->urbs);
+err_urbs:
+	kfree(buffer);
+	sgl_free(sgl);
+err_malloc:
+	usbip_event_add(ud, SDEV_EVENT_ERROR_MALLOC);
+}
+
+/* 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->udev->dev;
+
+	usbip_dbg_stub_rx("Enter\n");
+
+	memset(&pdu, 0, sizeof(pdu));
+
+	/* receive a pdu header */
+	ret = usbip_recv(ud->tcp_socket, &pdu, sizeof(pdu));
+	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 (usbip_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);
+		break;
+	}
+}
+
+int stub_rx_loop(void *data)
+{
+	struct usbip_device *ud = data;
+
+	while (!kthread_should_stop()) {
+		if (usbip_event_happened(ud))
+			break;
+
+		stub_rx_pdu(ud);
+	}
+
+	return 0;
+}
diff --git a/drivers/usb/usbip/stub_tx.c b/drivers/usb/usbip/stub_tx.c
new file mode 100644
index 000000000..36010a82b
--- /dev/null
+++ b/drivers/usb/usbip/stub_tx.c
@@ -0,0 +1,453 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (C) 2003-2008 Takahiro Hirofuchi
+ */
+
+#include <linux/kthread.h>
+#include <linux/socket.h>
+#include <linux/scatterlist.h>
+
+#include "usbip_common.h"
+#include "stub.h"
+
+/* 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) {
+		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
+ *
+ * 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;
+
+	usbip_dbg_stub_tx("complete! status %d\n", urb->status);
+
+	switch (urb->status) {
+	case 0:
+		/* OK */
+		break;
+	case -ENOENT:
+		dev_info(&urb->dev->dev,
+			 "stopped by a call to usb_kill_urb() because of cleaning up a virtual connection\n");
+		return;
+	case -ECONNRESET:
+		dev_info(&urb->dev->dev,
+			 "unlinked by a call to usb_unlink_urb()\n");
+		break;
+	case -EPIPE:
+		dev_info(&urb->dev->dev, "endpoint %d is stalled\n",
+			 usb_pipeendpoint(urb->pipe));
+		break;
+	case -ESHUTDOWN:
+		dev_info(&urb->dev->dev, "device removed?\n");
+		break;
+	default:
+		dev_info(&urb->dev->dev,
+			 "urb completion with non-zero status %d\n",
+			 urb->status);
+		break;
+	}
+
+	/*
+	 * If the server breaks single SG request into the several URBs, the
+	 * URBs must be reassembled before sending completed URB to the vhci.
+	 * Don't wake up the tx thread until all the URBs are completed.
+	 */
+	if (priv->sgl) {
+		priv->completed_urbs++;
+
+		/* Only save the first error status */
+		if (urb->status && !priv->urb_status)
+			priv->urb_status = urb->status;
+
+		if (priv->completed_urbs < priv->num_urbs)
+			return;
+	}
+
+	/* link a urb to the queue of tx. */
+	spin_lock_irqsave(&sdev->priv_lock, flags);
+	if (sdev->ud.tcp_socket == NULL) {
+		usbip_dbg_stub_tx("ignore urb for closed connection\n");
+		/* It will be freed in stub_device_cleanup_urbs(). */
+	} else 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);
+}
+
+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;
+}
+
+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;
+	size_t txsize;
+
+	size_t total_size = 0;
+
+	while ((priv = dequeue_from_priv_tx(sdev)) != NULL) {
+		struct urb *urb = priv->urbs[0];
+		struct usbip_header pdu_header;
+		struct usbip_iso_packet_descriptor *iso_buffer = NULL;
+		struct kvec *iov = NULL;
+		struct scatterlist *sg;
+		u32 actual_length = 0;
+		int iovnum = 0;
+		int ret;
+		int i;
+
+		txsize = 0;
+		memset(&pdu_header, 0, sizeof(pdu_header));
+		memset(&msg, 0, sizeof(msg));
+
+		if (urb->actual_length > 0 && !urb->transfer_buffer &&
+		   !urb->num_sgs) {
+			dev_err(&sdev->udev->dev,
+				"urb: actual_length %d transfer_buffer null\n",
+				urb->actual_length);
+			return -1;
+		}
+
+		if (usb_pipetype(urb->pipe) == PIPE_ISOCHRONOUS)
+			iovnum = 2 + urb->number_of_packets;
+		else if (usb_pipein(urb->pipe) && urb->actual_length > 0 &&
+			urb->num_sgs)
+			iovnum = 1 + urb->num_sgs;
+		else if (usb_pipein(urb->pipe) && priv->sgl)
+			iovnum = 1 + priv->num_urbs;
+		else
+			iovnum = 2;
+
+		iov = kcalloc(iovnum, sizeof(struct kvec), GFP_KERNEL);
+
+		if (!iov) {
+			usbip_event_add(&sdev->ud, SDEV_EVENT_ERROR_MALLOC);
+			return -1;
+		}
+
+		iovnum = 0;
+
+		/* 1. setup usbip_header */
+		setup_ret_submit_pdu(&pdu_header, urb);
+		usbip_dbg_stub_tx("setup txdata seqnum: %d\n",
+				  pdu_header.base.seqnum);
+
+		if (priv->sgl) {
+			for (i = 0; i < priv->num_urbs; i++)
+				actual_length += priv->urbs[i]->actual_length;
+
+			pdu_header.u.ret_submit.status = priv->urb_status;
+			pdu_header.u.ret_submit.actual_length = actual_length;
+		}
+
+		usbip_header_correct_endian(&pdu_header, 1);
+
+		iov[iovnum].iov_base = &pdu_header;
+		iov[iovnum].iov_len  = sizeof(pdu_header);
+		iovnum++;
+		txsize += sizeof(pdu_header);
+
+		/* 2. setup transfer buffer */
+		if (usb_pipein(urb->pipe) && priv->sgl) {
+			/* If the server split a single SG request into several
+			 * URBs because the server's HCD doesn't support SG,
+			 * reassemble the split URB buffers into a single
+			 * return command.
+			 */
+			for (i = 0; i < priv->num_urbs; i++) {
+				iov[iovnum].iov_base =
+					priv->urbs[i]->transfer_buffer;
+				iov[iovnum].iov_len =
+					priv->urbs[i]->actual_length;
+				iovnum++;
+			}
+			txsize += actual_length;
+		} else if (usb_pipein(urb->pipe) &&
+		    usb_pipetype(urb->pipe) != PIPE_ISOCHRONOUS &&
+		    urb->actual_length > 0) {
+			if (urb->num_sgs) {
+				unsigned int copy = urb->actual_length;
+				int size;
+
+				for_each_sg(urb->sg, sg, urb->num_sgs, i) {
+					if (copy == 0)
+						break;
+
+					if (copy < sg->length)
+						size = copy;
+					else
+						size = sg->length;
+
+					iov[iovnum].iov_base = sg_virt(sg);
+					iov[iovnum].iov_len = size;
+
+					iovnum++;
+					copy -= size;
+				}
+			} else {
+				iov[iovnum].iov_base = urb->transfer_buffer;
+				iov[iovnum].iov_len  = urb->actual_length;
+				iovnum++;
+			}
+			txsize += urb->actual_length;
+		} else if (usb_pipein(urb->pipe) &&
+			   usb_pipetype(urb->pipe) == PIPE_ISOCHRONOUS) {
+			/*
+			 * For isochronous packets: actual length is the sum of
+			 * the actual length of the individual, packets, but as
+			 * the packet offsets are not changed there will be
+			 * padding between the packets. To optimally use the
+			 * bandwidth the padding is not transmitted.
+			 */
+
+			int i;
+
+			for (i = 0; i < urb->number_of_packets; i++) {
+				iov[iovnum].iov_base = urb->transfer_buffer +
+					urb->iso_frame_desc[i].offset;
+				iov[iovnum].iov_len =
+					urb->iso_frame_desc[i].actual_length;
+				iovnum++;
+				txsize += urb->iso_frame_desc[i].actual_length;
+			}
+
+			if (txsize != sizeof(pdu_header) + urb->actual_length) {
+				dev_err(&sdev->udev->dev,
+					"actual length of urb %d does not match iso packet sizes %zu\n",
+					urb->actual_length,
+					txsize-sizeof(pdu_header));
+				kfree(iov);
+				usbip_event_add(&sdev->ud,
+						SDEV_EVENT_ERROR_TCP);
+			   return -1;
+			}
+		}
+
+		/* 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);
+				kfree(iov);
+				return -1;
+			}
+
+			iov[iovnum].iov_base = iso_buffer;
+			iov[iovnum].iov_len  = len;
+			txsize += len;
+			iovnum++;
+		}
+
+		ret = kernel_sendmsg(sdev->ud.tcp_socket, &msg,
+						iov,  iovnum, txsize);
+		if (ret != txsize) {
+			dev_err(&sdev->udev->dev,
+				"sendmsg failed!, retval %d for %zd\n",
+				ret, txsize);
+			kfree(iov);
+			kfree(iso_buffer);
+			usbip_event_add(&sdev->ud, SDEV_EVENT_ERROR_TCP);
+			return -1;
+		}
+
+		kfree(iov);
+		kfree(iso_buffer);
+
+		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;
+}
+
+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));
+
+		usbip_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->udev->dev,
+				"sendmsg failed!, retval %d for %zd\n",
+				ret, txsize);
+			usbip_event_add(&sdev->ud, SDEV_EVENT_ERROR_TCP);
+			return -1;
+		}
+
+		usbip_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;
+}
+
+int stub_tx_loop(void *data)
+{
+	struct usbip_device *ud = data;
+	struct stub_device *sdev = container_of(ud, struct stub_device, ud);
+
+	while (!kthread_should_stop()) {
+		if (usbip_event_happened(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) ||
+					  kthread_should_stop()));
+	}
+
+	return 0;
+}
diff --git a/drivers/usb/usbip/usbip_common.c b/drivers/usb/usbip/usbip_common.c
new file mode 100644
index 000000000..88eaf3c45
--- /dev/null
+++ b/drivers/usb/usbip/usbip_common.c
@@ -0,0 +1,778 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (C) 2003-2008 Takahiro Hirofuchi
+ * Copyright (C) 2015-2016 Samsung Electronics
+ *               Krzysztof Opasiak <k.opasiak@samsung.com>
+ */
+
+#include <asm/byteorder.h>
+#include <linux/file.h>
+#include <linux/fs.h>
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/stat.h>
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <net/sock.h>
+
+#include "usbip_common.h"
+
+#define DRIVER_AUTHOR "Takahiro Hirofuchi <hirofuchi@users.sourceforge.net>"
+#define DRIVER_DESC "USB/IP Core"
+
+#ifdef CONFIG_USBIP_DEBUG
+unsigned long usbip_debug_flag = 0xffffffff;
+#else
+unsigned long usbip_debug_flag;
+#endif
+EXPORT_SYMBOL_GPL(usbip_debug_flag);
+module_param(usbip_debug_flag, ulong, S_IRUGO|S_IWUSR);
+MODULE_PARM_DESC(usbip_debug_flag, "debug flags (defined in usbip_common.h)");
+
+/* FIXME */
+struct device_attribute dev_attr_usbip_debug;
+EXPORT_SYMBOL_GPL(dev_attr_usbip_debug);
+
+static ssize_t usbip_debug_show(struct device *dev,
+				struct device_attribute *attr, char *buf)
+{
+	return sprintf(buf, "%lx\n", usbip_debug_flag);
+}
+
+static ssize_t usbip_debug_store(struct device *dev,
+				 struct device_attribute *attr, const char *buf,
+				 size_t count)
+{
+	if (sscanf(buf, "%lx", &usbip_debug_flag) != 1)
+		return -EINVAL;
+	return count;
+}
+DEVICE_ATTR_RW(usbip_debug);
+
+static void usbip_dump_buffer(char *buff, int bufflen)
+{
+	print_hex_dump(KERN_DEBUG, "usbip-core", DUMP_PREFIX_OFFSET, 16, 4,
+		       buff, bufflen, false);
+}
+
+static void usbip_dump_pipe(unsigned int p)
+{
+	unsigned char type = usb_pipetype(p);
+	unsigned char ep   = usb_pipeendpoint(p);
+	unsigned char dev  = usb_pipedevice(p);
+	unsigned char dir  = usb_pipein(p);
+
+	pr_debug("dev(%d) ep(%d) [%s] ", dev, ep, dir ? "IN" : "OUT");
+
+	switch (type) {
+	case PIPE_ISOCHRONOUS:
+		pr_debug("ISO\n");
+		break;
+	case PIPE_INTERRUPT:
+		pr_debug("INT\n");
+		break;
+	case PIPE_CONTROL:
+		pr_debug("CTRL\n");
+		break;
+	case PIPE_BULK:
+		pr_debug("BULK\n");
+		break;
+	default:
+		pr_debug("ERR\n");
+		break;
+	}
+}
+
+static void usbip_dump_usb_device(struct usb_device *udev)
+{
+	struct device *dev = &udev->dev;
+	int i;
+
+	dev_dbg(dev, "       devnum(%d) devpath(%s) usb speed(%s)",
+		udev->devnum, udev->devpath, usb_speed_string(udev->speed));
+
+	pr_debug("tt hub ttport %d\n", udev->ttport);
+
+	dev_dbg(dev, "                    ");
+	for (i = 0; i < 16; i++)
+		pr_debug(" %2u", i);
+	pr_debug("\n");
+
+	dev_dbg(dev, "       toggle0(IN) :");
+	for (i = 0; i < 16; i++)
+		pr_debug(" %2u", (udev->toggle[0] & (1 << i)) ? 1 : 0);
+	pr_debug("\n");
+
+	dev_dbg(dev, "       toggle1(OUT):");
+	for (i = 0; i < 16; i++)
+		pr_debug(" %2u", (udev->toggle[1] & (1 << i)) ? 1 : 0);
+	pr_debug("\n");
+
+	dev_dbg(dev, "       epmaxp_in   :");
+	for (i = 0; i < 16; i++) {
+		if (udev->ep_in[i])
+			pr_debug(" %2u",
+			    le16_to_cpu(udev->ep_in[i]->desc.wMaxPacketSize));
+	}
+	pr_debug("\n");
+
+	dev_dbg(dev, "       epmaxp_out  :");
+	for (i = 0; i < 16; i++) {
+		if (udev->ep_out[i])
+			pr_debug(" %2u",
+			    le16_to_cpu(udev->ep_out[i]->desc.wMaxPacketSize));
+	}
+	pr_debug("\n");
+
+	dev_dbg(dev, "parent %s, bus %s\n", dev_name(&udev->parent->dev),
+		udev->bus->bus_name);
+
+	dev_dbg(dev, "have_langid %d, string_langid %d\n",
+		udev->have_langid, udev->string_langid);
+
+	dev_dbg(dev, "maxchild %d\n", udev->maxchild);
+}
+
+static void usbip_dump_request_type(__u8 rt)
+{
+	switch (rt & USB_RECIP_MASK) {
+	case USB_RECIP_DEVICE:
+		pr_debug("DEVICE");
+		break;
+	case USB_RECIP_INTERFACE:
+		pr_debug("INTERF");
+		break;
+	case USB_RECIP_ENDPOINT:
+		pr_debug("ENDPOI");
+		break;
+	case USB_RECIP_OTHER:
+		pr_debug("OTHER ");
+		break;
+	default:
+		pr_debug("------");
+		break;
+	}
+}
+
+static void usbip_dump_usb_ctrlrequest(struct usb_ctrlrequest *cmd)
+{
+	if (!cmd) {
+		pr_debug("       : null pointer\n");
+		return;
+	}
+
+	pr_debug("       ");
+	pr_debug("bRequestType(%02X) bRequest(%02X) wValue(%04X) wIndex(%04X) wLength(%04X) ",
+		 cmd->bRequestType, cmd->bRequest,
+		 cmd->wValue, cmd->wIndex, cmd->wLength);
+	pr_debug("\n       ");
+
+	if ((cmd->bRequestType & USB_TYPE_MASK) == USB_TYPE_STANDARD) {
+		pr_debug("STANDARD ");
+		switch (cmd->bRequest) {
+		case USB_REQ_GET_STATUS:
+			pr_debug("GET_STATUS\n");
+			break;
+		case USB_REQ_CLEAR_FEATURE:
+			pr_debug("CLEAR_FEAT\n");
+			break;
+		case USB_REQ_SET_FEATURE:
+			pr_debug("SET_FEAT\n");
+			break;
+		case USB_REQ_SET_ADDRESS:
+			pr_debug("SET_ADDRRS\n");
+			break;
+		case USB_REQ_GET_DESCRIPTOR:
+			pr_debug("GET_DESCRI\n");
+			break;
+		case USB_REQ_SET_DESCRIPTOR:
+			pr_debug("SET_DESCRI\n");
+			break;
+		case USB_REQ_GET_CONFIGURATION:
+			pr_debug("GET_CONFIG\n");
+			break;
+		case USB_REQ_SET_CONFIGURATION:
+			pr_debug("SET_CONFIG\n");
+			break;
+		case USB_REQ_GET_INTERFACE:
+			pr_debug("GET_INTERF\n");
+			break;
+		case USB_REQ_SET_INTERFACE:
+			pr_debug("SET_INTERF\n");
+			break;
+		case USB_REQ_SYNCH_FRAME:
+			pr_debug("SYNC_FRAME\n");
+			break;
+		default:
+			pr_debug("REQ(%02X)\n", cmd->bRequest);
+			break;
+		}
+		usbip_dump_request_type(cmd->bRequestType);
+	} else if ((cmd->bRequestType & USB_TYPE_MASK) == USB_TYPE_CLASS) {
+		pr_debug("CLASS\n");
+	} else if ((cmd->bRequestType & USB_TYPE_MASK) == USB_TYPE_VENDOR) {
+		pr_debug("VENDOR\n");
+	} else if ((cmd->bRequestType & USB_TYPE_MASK) == USB_TYPE_RESERVED) {
+		pr_debug("RESERVED\n");
+	}
+}
+
+void usbip_dump_urb(struct urb *urb)
+{
+	struct device *dev;
+
+	if (!urb) {
+		pr_debug("urb: null pointer!!\n");
+		return;
+	}
+
+	if (!urb->dev) {
+		pr_debug("urb->dev: null pointer!!\n");
+		return;
+	}
+
+	dev = &urb->dev->dev;
+
+	usbip_dump_usb_device(urb->dev);
+
+	dev_dbg(dev, "   pipe                  :%08x ", urb->pipe);
+
+	usbip_dump_pipe(urb->pipe);
+
+	dev_dbg(dev, "   status                :%d\n", urb->status);
+	dev_dbg(dev, "   transfer_flags        :%08X\n", urb->transfer_flags);
+	dev_dbg(dev, "   transfer_buffer_length:%d\n",
+						urb->transfer_buffer_length);
+	dev_dbg(dev, "   actual_length         :%d\n", urb->actual_length);
+
+	if (urb->setup_packet && usb_pipetype(urb->pipe) == PIPE_CONTROL)
+		usbip_dump_usb_ctrlrequest(
+			(struct usb_ctrlrequest *)urb->setup_packet);
+
+	dev_dbg(dev, "   start_frame           :%d\n", urb->start_frame);
+	dev_dbg(dev, "   number_of_packets     :%d\n", urb->number_of_packets);
+	dev_dbg(dev, "   interval              :%d\n", urb->interval);
+	dev_dbg(dev, "   error_count           :%d\n", urb->error_count);
+}
+EXPORT_SYMBOL_GPL(usbip_dump_urb);
+
+void usbip_dump_header(struct usbip_header *pdu)
+{
+	pr_debug("BASE: cmd %u seq %u devid %u dir %u ep %u\n",
+		 pdu->base.command,
+		 pdu->base.seqnum,
+		 pdu->base.devid,
+		 pdu->base.direction,
+		 pdu->base.ep);
+
+	switch (pdu->base.command) {
+	case USBIP_CMD_SUBMIT:
+		pr_debug("USBIP_CMD_SUBMIT: x_flags %u x_len %u sf %u #p %d iv %d\n",
+			 pdu->u.cmd_submit.transfer_flags,
+			 pdu->u.cmd_submit.transfer_buffer_length,
+			 pdu->u.cmd_submit.start_frame,
+			 pdu->u.cmd_submit.number_of_packets,
+			 pdu->u.cmd_submit.interval);
+		break;
+	case USBIP_CMD_UNLINK:
+		pr_debug("USBIP_CMD_UNLINK: seq %u\n",
+			 pdu->u.cmd_unlink.seqnum);
+		break;
+	case USBIP_RET_SUBMIT:
+		pr_debug("USBIP_RET_SUBMIT: st %d al %u sf %d #p %d ec %d\n",
+			 pdu->u.ret_submit.status,
+			 pdu->u.ret_submit.actual_length,
+			 pdu->u.ret_submit.start_frame,
+			 pdu->u.ret_submit.number_of_packets,
+			 pdu->u.ret_submit.error_count);
+		break;
+	case USBIP_RET_UNLINK:
+		pr_debug("USBIP_RET_UNLINK: status %d\n",
+			 pdu->u.ret_unlink.status);
+		break;
+	default:
+		/* NOT REACHED */
+		pr_err("unknown command\n");
+		break;
+	}
+}
+EXPORT_SYMBOL_GPL(usbip_dump_header);
+
+/* Receive data over TCP/IP. */
+int usbip_recv(struct socket *sock, void *buf, int size)
+{
+	int result;
+	struct kvec iov = {.iov_base = buf, .iov_len = size};
+	struct msghdr msg = {.msg_flags = MSG_NOSIGNAL};
+	int total = 0;
+
+	if (!sock || !buf || !size)
+		return -EINVAL;
+
+	iov_iter_kvec(&msg.msg_iter, READ|ITER_KVEC, &iov, 1, size);
+
+	usbip_dbg_xmit("enter\n");
+
+	do {
+		sock->sk->sk_allocation = GFP_NOIO;
+
+		result = sock_recvmsg(sock, &msg, MSG_WAITALL);
+		if (result <= 0)
+			goto err;
+
+		total += result;
+	} while (msg_data_left(&msg));
+
+	if (usbip_dbg_flag_xmit) {
+		if (!in_interrupt())
+			pr_debug("%-10s:", current->comm);
+		else
+			pr_debug("interrupt  :");
+
+		pr_debug("receiving....\n");
+		usbip_dump_buffer(buf, size);
+		pr_debug("received, osize %d ret %d size %zd total %d\n",
+			 size, result, msg_data_left(&msg), total);
+	}
+
+	return total;
+
+err:
+	return result;
+}
+EXPORT_SYMBOL_GPL(usbip_recv);
+
+/* there may be more cases to tweak the flags. */
+static unsigned int tweak_transfer_flags(unsigned int flags)
+{
+	flags &= ~URB_NO_TRANSFER_DMA_MAP;
+	return flags;
+}
+
+static void usbip_pack_cmd_submit(struct usbip_header *pdu, struct urb *urb,
+				  int pack)
+{
+	struct usbip_header_cmd_submit *spdu = &pdu->u.cmd_submit;
+
+	/*
+	 * Some members are not still implemented in usbip. I hope this issue
+	 * will be discussed when usbip is ported to other operating systems.
+	 */
+	if (pack) {
+		spdu->transfer_flags =
+			tweak_transfer_flags(urb->transfer_flags);
+		spdu->transfer_buffer_length	= urb->transfer_buffer_length;
+		spdu->start_frame		= urb->start_frame;
+		spdu->number_of_packets		= urb->number_of_packets;
+		spdu->interval			= urb->interval;
+	} else  {
+		urb->transfer_flags         = spdu->transfer_flags;
+		urb->transfer_buffer_length = spdu->transfer_buffer_length;
+		urb->start_frame            = spdu->start_frame;
+		urb->number_of_packets      = spdu->number_of_packets;
+		urb->interval               = spdu->interval;
+	}
+}
+
+static void usbip_pack_ret_submit(struct usbip_header *pdu, struct urb *urb,
+				  int pack)
+{
+	struct usbip_header_ret_submit *rpdu = &pdu->u.ret_submit;
+
+	if (pack) {
+		rpdu->status		= urb->status;
+		rpdu->actual_length	= urb->actual_length;
+		rpdu->start_frame	= urb->start_frame;
+		rpdu->number_of_packets = urb->number_of_packets;
+		rpdu->error_count	= urb->error_count;
+	} else {
+		urb->status		= rpdu->status;
+		urb->actual_length	= rpdu->actual_length;
+		urb->start_frame	= rpdu->start_frame;
+		urb->number_of_packets = rpdu->number_of_packets;
+		urb->error_count	= rpdu->error_count;
+	}
+}
+
+void usbip_pack_pdu(struct usbip_header *pdu, struct urb *urb, int cmd,
+		    int pack)
+{
+	switch (cmd) {
+	case USBIP_CMD_SUBMIT:
+		usbip_pack_cmd_submit(pdu, urb, pack);
+		break;
+	case USBIP_RET_SUBMIT:
+		usbip_pack_ret_submit(pdu, urb, pack);
+		break;
+	default:
+		/* NOT REACHED */
+		pr_err("unknown command\n");
+		break;
+	}
+}
+EXPORT_SYMBOL_GPL(usbip_pack_pdu);
+
+static void correct_endian_basic(struct usbip_header_basic *base, int send)
+{
+	if (send) {
+		base->command	= cpu_to_be32(base->command);
+		base->seqnum	= cpu_to_be32(base->seqnum);
+		base->devid	= cpu_to_be32(base->devid);
+		base->direction	= cpu_to_be32(base->direction);
+		base->ep	= cpu_to_be32(base->ep);
+	} else {
+		base->command	= be32_to_cpu(base->command);
+		base->seqnum	= be32_to_cpu(base->seqnum);
+		base->devid	= be32_to_cpu(base->devid);
+		base->direction	= be32_to_cpu(base->direction);
+		base->ep	= be32_to_cpu(base->ep);
+	}
+}
+
+static void correct_endian_cmd_submit(struct usbip_header_cmd_submit *pdu,
+				      int send)
+{
+	if (send) {
+		pdu->transfer_flags = cpu_to_be32(pdu->transfer_flags);
+
+		cpu_to_be32s(&pdu->transfer_buffer_length);
+		cpu_to_be32s(&pdu->start_frame);
+		cpu_to_be32s(&pdu->number_of_packets);
+		cpu_to_be32s(&pdu->interval);
+	} else {
+		pdu->transfer_flags = be32_to_cpu(pdu->transfer_flags);
+
+		be32_to_cpus(&pdu->transfer_buffer_length);
+		be32_to_cpus(&pdu->start_frame);
+		be32_to_cpus(&pdu->number_of_packets);
+		be32_to_cpus(&pdu->interval);
+	}
+}
+
+static void correct_endian_ret_submit(struct usbip_header_ret_submit *pdu,
+				      int send)
+{
+	if (send) {
+		cpu_to_be32s(&pdu->status);
+		cpu_to_be32s(&pdu->actual_length);
+		cpu_to_be32s(&pdu->start_frame);
+		cpu_to_be32s(&pdu->number_of_packets);
+		cpu_to_be32s(&pdu->error_count);
+	} else {
+		be32_to_cpus(&pdu->status);
+		be32_to_cpus(&pdu->actual_length);
+		be32_to_cpus(&pdu->start_frame);
+		be32_to_cpus(&pdu->number_of_packets);
+		be32_to_cpus(&pdu->error_count);
+	}
+}
+
+static void correct_endian_cmd_unlink(struct usbip_header_cmd_unlink *pdu,
+				      int send)
+{
+	if (send)
+		pdu->seqnum = cpu_to_be32(pdu->seqnum);
+	else
+		pdu->seqnum = be32_to_cpu(pdu->seqnum);
+}
+
+static void correct_endian_ret_unlink(struct usbip_header_ret_unlink *pdu,
+				      int send)
+{
+	if (send)
+		cpu_to_be32s(&pdu->status);
+	else
+		be32_to_cpus(&pdu->status);
+}
+
+void usbip_header_correct_endian(struct usbip_header *pdu, int send)
+{
+	__u32 cmd = 0;
+
+	if (send)
+		cmd = pdu->base.command;
+
+	correct_endian_basic(&pdu->base, send);
+
+	if (!send)
+		cmd = pdu->base.command;
+
+	switch (cmd) {
+	case USBIP_CMD_SUBMIT:
+		correct_endian_cmd_submit(&pdu->u.cmd_submit, send);
+		break;
+	case USBIP_RET_SUBMIT:
+		correct_endian_ret_submit(&pdu->u.ret_submit, send);
+		break;
+	case USBIP_CMD_UNLINK:
+		correct_endian_cmd_unlink(&pdu->u.cmd_unlink, send);
+		break;
+	case USBIP_RET_UNLINK:
+		correct_endian_ret_unlink(&pdu->u.ret_unlink, send);
+		break;
+	default:
+		/* NOT REACHED */
+		pr_err("unknown command\n");
+		break;
+	}
+}
+EXPORT_SYMBOL_GPL(usbip_header_correct_endian);
+
+static void usbip_iso_packet_correct_endian(
+		struct usbip_iso_packet_descriptor *iso, int send)
+{
+	/* does not need all members. but copy all simply. */
+	if (send) {
+		iso->offset	= cpu_to_be32(iso->offset);
+		iso->length	= cpu_to_be32(iso->length);
+		iso->status	= cpu_to_be32(iso->status);
+		iso->actual_length = cpu_to_be32(iso->actual_length);
+	} else {
+		iso->offset	= be32_to_cpu(iso->offset);
+		iso->length	= be32_to_cpu(iso->length);
+		iso->status	= be32_to_cpu(iso->status);
+		iso->actual_length = be32_to_cpu(iso->actual_length);
+	}
+}
+
+static void usbip_pack_iso(struct usbip_iso_packet_descriptor *iso,
+			   struct usb_iso_packet_descriptor *uiso, int pack)
+{
+	if (pack) {
+		iso->offset		= uiso->offset;
+		iso->length		= uiso->length;
+		iso->status		= uiso->status;
+		iso->actual_length	= uiso->actual_length;
+	} else {
+		uiso->offset		= iso->offset;
+		uiso->length		= iso->length;
+		uiso->status		= iso->status;
+		uiso->actual_length	= iso->actual_length;
+	}
+}
+
+/* must free buffer */
+struct usbip_iso_packet_descriptor*
+usbip_alloc_iso_desc_pdu(struct urb *urb, ssize_t *bufflen)
+{
+	struct usbip_iso_packet_descriptor *iso;
+	int np = urb->number_of_packets;
+	ssize_t size = np * sizeof(*iso);
+	int i;
+
+	iso = kzalloc(size, GFP_KERNEL);
+	if (!iso)
+		return NULL;
+
+	for (i = 0; i < np; i++) {
+		usbip_pack_iso(&iso[i], &urb->iso_frame_desc[i], 1);
+		usbip_iso_packet_correct_endian(&iso[i], 1);
+	}
+
+	*bufflen = size;
+
+	return iso;
+}
+EXPORT_SYMBOL_GPL(usbip_alloc_iso_desc_pdu);
+
+/* some members of urb must be substituted before. */
+int usbip_recv_iso(struct usbip_device *ud, struct urb *urb)
+{
+	void *buff;
+	struct usbip_iso_packet_descriptor *iso;
+	int np = urb->number_of_packets;
+	int size = np * sizeof(*iso);
+	int i;
+	int ret;
+	int total_length = 0;
+
+	if (!usb_pipeisoc(urb->pipe))
+		return 0;
+
+	/* my Bluetooth dongle gets ISO URBs which are np = 0 */
+	if (np == 0)
+		return 0;
+
+	buff = kzalloc(size, GFP_KERNEL);
+	if (!buff)
+		return -ENOMEM;
+
+	ret = usbip_recv(ud->tcp_socket, buff, size);
+	if (ret != size) {
+		dev_err(&urb->dev->dev, "recv iso_frame_descriptor, %d\n",
+			ret);
+		kfree(buff);
+
+		if (ud->side == USBIP_STUB || ud->side == USBIP_VUDC)
+			usbip_event_add(ud, SDEV_EVENT_ERROR_TCP);
+		else
+			usbip_event_add(ud, VDEV_EVENT_ERROR_TCP);
+
+		return -EPIPE;
+	}
+
+	iso = (struct usbip_iso_packet_descriptor *) buff;
+	for (i = 0; i < np; i++) {
+		usbip_iso_packet_correct_endian(&iso[i], 0);
+		usbip_pack_iso(&iso[i], &urb->iso_frame_desc[i], 0);
+		total_length += urb->iso_frame_desc[i].actual_length;
+	}
+
+	kfree(buff);
+
+	if (total_length != urb->actual_length) {
+		dev_err(&urb->dev->dev,
+			"total length of iso packets %d not equal to actual length of buffer %d\n",
+			total_length, urb->actual_length);
+
+		if (ud->side == USBIP_STUB || ud->side == USBIP_VUDC)
+			usbip_event_add(ud, SDEV_EVENT_ERROR_TCP);
+		else
+			usbip_event_add(ud, VDEV_EVENT_ERROR_TCP);
+
+		return -EPIPE;
+	}
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(usbip_recv_iso);
+
+/*
+ * This functions restores the padding which was removed for optimizing
+ * the bandwidth during transfer over tcp/ip
+ *
+ * buffer and iso packets need to be stored and be in propeper endian in urb
+ * before calling this function
+ */
+void usbip_pad_iso(struct usbip_device *ud, struct urb *urb)
+{
+	int np = urb->number_of_packets;
+	int i;
+	int actualoffset = urb->actual_length;
+
+	if (!usb_pipeisoc(urb->pipe))
+		return;
+
+	/* if no packets or length of data is 0, then nothing to unpack */
+	if (np == 0 || urb->actual_length == 0)
+		return;
+
+	/*
+	 * if actual_length is transfer_buffer_length then no padding is
+	 * present.
+	 */
+	if (urb->actual_length == urb->transfer_buffer_length)
+		return;
+
+	/*
+	 * loop over all packets from last to first (to prevent overwriting
+	 * memory when padding) and move them into the proper place
+	 */
+	for (i = np-1; i > 0; i--) {
+		actualoffset -= urb->iso_frame_desc[i].actual_length;
+		memmove(urb->transfer_buffer + urb->iso_frame_desc[i].offset,
+			urb->transfer_buffer + actualoffset,
+			urb->iso_frame_desc[i].actual_length);
+	}
+}
+EXPORT_SYMBOL_GPL(usbip_pad_iso);
+
+/* some members of urb must be substituted before. */
+int usbip_recv_xbuff(struct usbip_device *ud, struct urb *urb)
+{
+	struct scatterlist *sg;
+	int ret = 0;
+	int recv;
+	int size;
+	int copy;
+	int i;
+
+	if (ud->side == USBIP_STUB || ud->side == USBIP_VUDC) {
+		/* the direction of urb must be OUT. */
+		if (usb_pipein(urb->pipe))
+			return 0;
+
+		size = urb->transfer_buffer_length;
+	} else {
+		/* the direction of urb must be IN. */
+		if (usb_pipeout(urb->pipe))
+			return 0;
+
+		size = urb->actual_length;
+	}
+
+	/* no need to recv xbuff */
+	if (!(size > 0))
+		return 0;
+
+	if (size > urb->transfer_buffer_length)
+		/* should not happen, probably malicious packet */
+		goto error;
+
+	if (urb->num_sgs) {
+		copy = size;
+		for_each_sg(urb->sg, sg, urb->num_sgs, i) {
+			int recv_size;
+
+			if (copy < sg->length)
+				recv_size = copy;
+			else
+				recv_size = sg->length;
+
+			recv = usbip_recv(ud->tcp_socket, sg_virt(sg),
+						recv_size);
+
+			if (recv != recv_size)
+				goto error;
+
+			copy -= recv;
+			ret += recv;
+
+			if (!copy)
+				break;
+		}
+
+		if (ret != size)
+			goto error;
+	} else {
+		ret = usbip_recv(ud->tcp_socket, urb->transfer_buffer, size);
+		if (ret != size)
+			goto error;
+	}
+
+	return ret;
+
+error:
+	dev_err(&urb->dev->dev, "recv xbuf, %d\n", ret);
+	if (ud->side == USBIP_STUB || ud->side == USBIP_VUDC)
+		usbip_event_add(ud, SDEV_EVENT_ERROR_TCP);
+	else
+		usbip_event_add(ud, VDEV_EVENT_ERROR_TCP);
+
+	return -EPIPE;
+}
+EXPORT_SYMBOL_GPL(usbip_recv_xbuff);
+
+static int __init usbip_core_init(void)
+{
+	int ret;
+
+	ret = usbip_init_eh();
+	if (ret)
+		return ret;
+
+	return 0;
+}
+
+static void __exit usbip_core_exit(void)
+{
+	usbip_finish_eh();
+	return;
+}
+
+module_init(usbip_core_init);
+module_exit(usbip_core_exit);
+
+MODULE_AUTHOR(DRIVER_AUTHOR);
+MODULE_DESCRIPTION(DRIVER_DESC);
+MODULE_LICENSE("GPL");
diff --git a/drivers/usb/usbip/usbip_common.h b/drivers/usb/usbip/usbip_common.h
new file mode 100644
index 000000000..a7e6ce96f
--- /dev/null
+++ b/drivers/usb/usbip/usbip_common.h
@@ -0,0 +1,343 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (C) 2003-2008 Takahiro Hirofuchi
+ * Copyright (C) 2015-2016 Samsung Electronics
+ *               Krzysztof Opasiak <k.opasiak@samsung.com>
+ */
+
+#ifndef __USBIP_COMMON_H
+#define __USBIP_COMMON_H
+
+#include <linux/compiler.h>
+#include <linux/device.h>
+#include <linux/interrupt.h>
+#include <linux/net.h>
+#include <linux/printk.h>
+#include <linux/spinlock.h>
+#include <linux/types.h>
+#include <linux/usb.h>
+#include <linux/wait.h>
+#include <linux/sched/task.h>
+#include <uapi/linux/usbip.h>
+
+#undef pr_fmt
+
+#ifdef DEBUG
+#define pr_fmt(fmt)     KBUILD_MODNAME ": %s:%d: " fmt, __func__, __LINE__
+#else
+#define pr_fmt(fmt)     KBUILD_MODNAME ": " fmt
+#endif
+
+enum {
+	usbip_debug_xmit	= (1 << 0),
+	usbip_debug_sysfs	= (1 << 1),
+	usbip_debug_urb		= (1 << 2),
+	usbip_debug_eh		= (1 << 3),
+
+	usbip_debug_stub_cmp	= (1 << 8),
+	usbip_debug_stub_dev	= (1 << 9),
+	usbip_debug_stub_rx	= (1 << 10),
+	usbip_debug_stub_tx	= (1 << 11),
+
+	usbip_debug_vhci_rh	= (1 << 8),
+	usbip_debug_vhci_hc	= (1 << 9),
+	usbip_debug_vhci_rx	= (1 << 10),
+	usbip_debug_vhci_tx	= (1 << 11),
+	usbip_debug_vhci_sysfs  = (1 << 12)
+};
+
+#define usbip_dbg_flag_xmit	(usbip_debug_flag & usbip_debug_xmit)
+#define usbip_dbg_flag_vhci_rh	(usbip_debug_flag & usbip_debug_vhci_rh)
+#define usbip_dbg_flag_vhci_hc	(usbip_debug_flag & usbip_debug_vhci_hc)
+#define usbip_dbg_flag_vhci_rx	(usbip_debug_flag & usbip_debug_vhci_rx)
+#define usbip_dbg_flag_vhci_tx	(usbip_debug_flag & usbip_debug_vhci_tx)
+#define usbip_dbg_flag_stub_rx	(usbip_debug_flag & usbip_debug_stub_rx)
+#define usbip_dbg_flag_stub_tx	(usbip_debug_flag & usbip_debug_stub_tx)
+#define usbip_dbg_flag_vhci_sysfs  (usbip_debug_flag & usbip_debug_vhci_sysfs)
+
+extern unsigned long usbip_debug_flag;
+extern struct device_attribute dev_attr_usbip_debug;
+
+#define usbip_dbg_with_flag(flag, fmt, args...)		\
+	do {						\
+		if (flag & usbip_debug_flag)		\
+			pr_debug(fmt, ##args);		\
+	} while (0)
+
+#define usbip_dbg_sysfs(fmt, args...) \
+	usbip_dbg_with_flag(usbip_debug_sysfs, fmt , ##args)
+#define usbip_dbg_xmit(fmt, args...) \
+	usbip_dbg_with_flag(usbip_debug_xmit, fmt , ##args)
+#define usbip_dbg_urb(fmt, args...) \
+	usbip_dbg_with_flag(usbip_debug_urb, fmt , ##args)
+#define usbip_dbg_eh(fmt, args...) \
+	usbip_dbg_with_flag(usbip_debug_eh, fmt , ##args)
+
+#define usbip_dbg_vhci_rh(fmt, args...)	\
+	usbip_dbg_with_flag(usbip_debug_vhci_rh, fmt , ##args)
+#define usbip_dbg_vhci_hc(fmt, args...)	\
+	usbip_dbg_with_flag(usbip_debug_vhci_hc, fmt , ##args)
+#define usbip_dbg_vhci_rx(fmt, args...)	\
+	usbip_dbg_with_flag(usbip_debug_vhci_rx, fmt , ##args)
+#define usbip_dbg_vhci_tx(fmt, args...)	\
+	usbip_dbg_with_flag(usbip_debug_vhci_tx, fmt , ##args)
+#define usbip_dbg_vhci_sysfs(fmt, args...) \
+	usbip_dbg_with_flag(usbip_debug_vhci_sysfs, fmt , ##args)
+
+#define usbip_dbg_stub_cmp(fmt, args...) \
+	usbip_dbg_with_flag(usbip_debug_stub_cmp, fmt , ##args)
+#define usbip_dbg_stub_rx(fmt, args...) \
+	usbip_dbg_with_flag(usbip_debug_stub_rx, fmt , ##args)
+#define usbip_dbg_stub_tx(fmt, args...) \
+	usbip_dbg_with_flag(usbip_debug_stub_tx, fmt , ##args)
+
+/*
+ * USB/IP request headers
+ *
+ * Each request is transferred across the network to its counterpart, which
+ * facilitates the normal USB communication. The values contained in the headers
+ * are basically the same as in a URB. Currently, four request types are
+ * defined:
+ *
+ *  - USBIP_CMD_SUBMIT: a USB request block, corresponds to usb_submit_urb()
+ *    (client to server)
+ *
+ *  - USBIP_RET_SUBMIT: the result of USBIP_CMD_SUBMIT
+ *    (server to client)
+ *
+ *  - USBIP_CMD_UNLINK: an unlink request of a pending USBIP_CMD_SUBMIT,
+ *    corresponds to usb_unlink_urb()
+ *    (client to server)
+ *
+ *  - USBIP_RET_UNLINK: the result of USBIP_CMD_UNLINK
+ *    (server to client)
+ *
+ */
+#define USBIP_CMD_SUBMIT	0x0001
+#define USBIP_CMD_UNLINK	0x0002
+#define USBIP_RET_SUBMIT	0x0003
+#define USBIP_RET_UNLINK	0x0004
+
+#define USBIP_DIR_OUT	0x00
+#define USBIP_DIR_IN	0x01
+
+/*
+ * Arbitrary limit for the maximum number of isochronous packets in an URB,
+ * compare for example the uhci_submit_isochronous function in
+ * drivers/usb/host/uhci-q.c
+ */
+#define USBIP_MAX_ISO_PACKETS 1024
+
+/**
+ * struct usbip_header_basic - data pertinent to every request
+ * @command: the usbip request type
+ * @seqnum: sequential number that identifies requests; incremented per
+ *	    connection
+ * @devid: specifies a remote USB device uniquely instead of busnum and devnum;
+ *	   in the stub driver, this value is ((busnum << 16) | devnum)
+ * @direction: direction of the transfer
+ * @ep: endpoint number
+ */
+struct usbip_header_basic {
+	__u32 command;
+	__u32 seqnum;
+	__u32 devid;
+	__u32 direction;
+	__u32 ep;
+} __packed;
+
+/**
+ * struct usbip_header_cmd_submit - USBIP_CMD_SUBMIT packet header
+ * @transfer_flags: URB flags
+ * @transfer_buffer_length: the data size for (in) or (out) transfer
+ * @start_frame: initial frame for isochronous or interrupt transfers
+ * @number_of_packets: number of isochronous packets
+ * @interval: maximum time for the request on the server-side host controller
+ * @setup: setup data for a control request
+ */
+struct usbip_header_cmd_submit {
+	__u32 transfer_flags;
+	__s32 transfer_buffer_length;
+
+	/* it is difficult for usbip to sync frames (reserved only?) */
+	__s32 start_frame;
+	__s32 number_of_packets;
+	__s32 interval;
+
+	unsigned char setup[8];
+} __packed;
+
+/**
+ * struct usbip_header_ret_submit - USBIP_RET_SUBMIT packet header
+ * @status: return status of a non-iso request
+ * @actual_length: number of bytes transferred
+ * @start_frame: initial frame for isochronous or interrupt transfers
+ * @number_of_packets: number of isochronous packets
+ * @error_count: number of errors for isochronous transfers
+ */
+struct usbip_header_ret_submit {
+	__s32 status;
+	__s32 actual_length;
+	__s32 start_frame;
+	__s32 number_of_packets;
+	__s32 error_count;
+} __packed;
+
+/**
+ * struct usbip_header_cmd_unlink - USBIP_CMD_UNLINK packet header
+ * @seqnum: the URB seqnum to unlink
+ */
+struct usbip_header_cmd_unlink {
+	__u32 seqnum;
+} __packed;
+
+/**
+ * struct usbip_header_ret_unlink - USBIP_RET_UNLINK packet header
+ * @status: return status of the request
+ */
+struct usbip_header_ret_unlink {
+	__s32 status;
+} __packed;
+
+/**
+ * struct usbip_header - common header for all usbip packets
+ * @base: the basic header
+ * @u: packet type dependent header
+ */
+struct usbip_header {
+	struct usbip_header_basic base;
+
+	union {
+		struct usbip_header_cmd_submit	cmd_submit;
+		struct usbip_header_ret_submit	ret_submit;
+		struct usbip_header_cmd_unlink	cmd_unlink;
+		struct usbip_header_ret_unlink	ret_unlink;
+	} u;
+} __packed;
+
+/*
+ * This is the same as usb_iso_packet_descriptor but packed for pdu.
+ */
+struct usbip_iso_packet_descriptor {
+	__u32 offset;
+	__u32 length;			/* expected length */
+	__u32 actual_length;
+	__u32 status;
+} __packed;
+
+enum usbip_side {
+	USBIP_VHCI,
+	USBIP_STUB,
+	USBIP_VUDC,
+};
+
+/* event handler */
+#define USBIP_EH_SHUTDOWN	(1 << 0)
+#define USBIP_EH_BYE		(1 << 1)
+#define USBIP_EH_RESET		(1 << 2)
+#define USBIP_EH_UNUSABLE	(1 << 3)
+
+#define	SDEV_EVENT_REMOVED	(USBIP_EH_SHUTDOWN | USBIP_EH_BYE)
+#define	SDEV_EVENT_DOWN		(USBIP_EH_SHUTDOWN | USBIP_EH_RESET)
+#define	SDEV_EVENT_ERROR_TCP	(USBIP_EH_SHUTDOWN | USBIP_EH_RESET)
+#define	SDEV_EVENT_ERROR_SUBMIT	(USBIP_EH_SHUTDOWN | USBIP_EH_RESET)
+#define	SDEV_EVENT_ERROR_MALLOC	(USBIP_EH_SHUTDOWN | USBIP_EH_UNUSABLE)
+
+#define VUDC_EVENT_REMOVED   (USBIP_EH_SHUTDOWN | USBIP_EH_RESET | USBIP_EH_BYE)
+#define	VUDC_EVENT_DOWN		(USBIP_EH_SHUTDOWN | USBIP_EH_RESET)
+#define	VUDC_EVENT_ERROR_TCP	(USBIP_EH_SHUTDOWN | USBIP_EH_RESET)
+/* catastrophic emulated usb error */
+#define	VUDC_EVENT_ERROR_USB	(USBIP_EH_SHUTDOWN | USBIP_EH_UNUSABLE)
+#define	VUDC_EVENT_ERROR_MALLOC	(USBIP_EH_SHUTDOWN | USBIP_EH_UNUSABLE)
+
+#define	VDEV_EVENT_REMOVED (USBIP_EH_SHUTDOWN | USBIP_EH_RESET | USBIP_EH_BYE)
+#define	VDEV_EVENT_DOWN		(USBIP_EH_SHUTDOWN | USBIP_EH_RESET)
+#define	VDEV_EVENT_ERROR_TCP	(USBIP_EH_SHUTDOWN | USBIP_EH_RESET)
+#define	VDEV_EVENT_ERROR_MALLOC	(USBIP_EH_SHUTDOWN | USBIP_EH_UNUSABLE)
+
+/* a common structure for stub_device and vhci_device */
+struct usbip_device {
+	enum usbip_side side;
+	enum usbip_device_status status;
+
+	/* lock for status */
+	spinlock_t lock;
+
+	/* mutex for synchronizing sysfs store paths */
+	struct mutex sysfs_lock;
+
+	int sockfd;
+	struct socket *tcp_socket;
+
+	struct task_struct *tcp_rx;
+	struct task_struct *tcp_tx;
+
+	unsigned long event;
+	wait_queue_head_t eh_waitq;
+
+	struct eh_ops {
+		void (*shutdown)(struct usbip_device *);
+		void (*reset)(struct usbip_device *);
+		void (*unusable)(struct usbip_device *);
+	} eh_ops;
+};
+
+#define kthread_get_run(threadfn, data, namefmt, ...)			   \
+({									   \
+	struct task_struct *__k						   \
+		= kthread_create(threadfn, data, namefmt, ## __VA_ARGS__); \
+	if (!IS_ERR(__k)) {						   \
+		get_task_struct(__k);					   \
+		wake_up_process(__k);					   \
+	}								   \
+	__k;								   \
+})
+
+#define kthread_stop_put(k)		\
+	do {				\
+		kthread_stop(k);	\
+		put_task_struct(k);	\
+	} while (0)
+
+/* usbip_common.c */
+void usbip_dump_urb(struct urb *purb);
+void usbip_dump_header(struct usbip_header *pdu);
+
+int usbip_recv(struct socket *sock, void *buf, int size);
+
+void usbip_pack_pdu(struct usbip_header *pdu, struct urb *urb, int cmd,
+		    int pack);
+void usbip_header_correct_endian(struct usbip_header *pdu, int send);
+
+struct usbip_iso_packet_descriptor*
+usbip_alloc_iso_desc_pdu(struct urb *urb, ssize_t *bufflen);
+
+/* some members of urb must be substituted before. */
+int usbip_recv_iso(struct usbip_device *ud, struct urb *urb);
+void usbip_pad_iso(struct usbip_device *ud, struct urb *urb);
+int usbip_recv_xbuff(struct usbip_device *ud, struct urb *urb);
+
+/* usbip_event.c */
+int usbip_init_eh(void);
+void usbip_finish_eh(void);
+int usbip_start_eh(struct usbip_device *ud);
+void usbip_stop_eh(struct usbip_device *ud);
+void usbip_event_add(struct usbip_device *ud, unsigned long event);
+int usbip_event_happened(struct usbip_device *ud);
+int usbip_in_eh(struct task_struct *task);
+
+static inline int interface_to_busnum(struct usb_interface *interface)
+{
+	struct usb_device *udev = interface_to_usbdev(interface);
+
+	return udev->bus->busnum;
+}
+
+static inline int interface_to_devnum(struct usb_interface *interface)
+{
+	struct usb_device *udev = interface_to_usbdev(interface);
+
+	return udev->devnum;
+}
+
+#endif /* __USBIP_COMMON_H */
diff --git a/drivers/usb/usbip/usbip_event.c b/drivers/usb/usbip/usbip_event.c
new file mode 100644
index 000000000..086ca76dd
--- /dev/null
+++ b/drivers/usb/usbip/usbip_event.c
@@ -0,0 +1,197 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (C) 2003-2008 Takahiro Hirofuchi
+ * Copyright (C) 2015 Nobuo Iwata
+ */
+
+#include <linux/kthread.h>
+#include <linux/export.h>
+#include <linux/slab.h>
+#include <linux/workqueue.h>
+
+#include "usbip_common.h"
+
+struct usbip_event {
+	struct list_head node;
+	struct usbip_device *ud;
+};
+
+static DEFINE_SPINLOCK(event_lock);
+static LIST_HEAD(event_list);
+
+static void set_event(struct usbip_device *ud, unsigned long event)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&ud->lock, flags);
+	ud->event |= event;
+	spin_unlock_irqrestore(&ud->lock, flags);
+}
+
+static void unset_event(struct usbip_device *ud, unsigned long event)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&ud->lock, flags);
+	ud->event &= ~event;
+	spin_unlock_irqrestore(&ud->lock, flags);
+}
+
+static struct usbip_device *get_event(void)
+{
+	struct usbip_event *ue = NULL;
+	struct usbip_device *ud = NULL;
+	unsigned long flags;
+
+	spin_lock_irqsave(&event_lock, flags);
+	if (!list_empty(&event_list)) {
+		ue = list_first_entry(&event_list, struct usbip_event, node);
+		list_del(&ue->node);
+	}
+	spin_unlock_irqrestore(&event_lock, flags);
+
+	if (ue) {
+		ud = ue->ud;
+		kfree(ue);
+	}
+	return ud;
+}
+
+static struct task_struct *worker_context;
+
+static void event_handler(struct work_struct *work)
+{
+	struct usbip_device *ud;
+
+	if (worker_context == NULL) {
+		worker_context = current;
+	}
+
+	while ((ud = get_event()) != NULL) {
+		usbip_dbg_eh("pending event %lx\n", ud->event);
+
+		mutex_lock(&ud->sysfs_lock);
+		/*
+		 * NOTE: shutdown must come first.
+		 * Shutdown the device.
+		 */
+		if (ud->event & USBIP_EH_SHUTDOWN) {
+			ud->eh_ops.shutdown(ud);
+			unset_event(ud, USBIP_EH_SHUTDOWN);
+		}
+
+		/* Reset the device. */
+		if (ud->event & USBIP_EH_RESET) {
+			ud->eh_ops.reset(ud);
+			unset_event(ud, USBIP_EH_RESET);
+		}
+
+		/* Mark the device as unusable. */
+		if (ud->event & USBIP_EH_UNUSABLE) {
+			ud->eh_ops.unusable(ud);
+			unset_event(ud, USBIP_EH_UNUSABLE);
+		}
+		mutex_unlock(&ud->sysfs_lock);
+
+		wake_up(&ud->eh_waitq);
+	}
+}
+
+int usbip_start_eh(struct usbip_device *ud)
+{
+	init_waitqueue_head(&ud->eh_waitq);
+	ud->event = 0;
+	return 0;
+}
+EXPORT_SYMBOL_GPL(usbip_start_eh);
+
+void usbip_stop_eh(struct usbip_device *ud)
+{
+	unsigned long pending = ud->event & ~USBIP_EH_BYE;
+
+	if (!(ud->event & USBIP_EH_BYE))
+		usbip_dbg_eh("usbip_eh stopping but not removed\n");
+
+	if (pending)
+		usbip_dbg_eh("usbip_eh waiting completion %lx\n", pending);
+
+	wait_event_interruptible(ud->eh_waitq, !(ud->event & ~USBIP_EH_BYE));
+	usbip_dbg_eh("usbip_eh has stopped\n");
+}
+EXPORT_SYMBOL_GPL(usbip_stop_eh);
+
+#define WORK_QUEUE_NAME "usbip_event"
+
+static struct workqueue_struct *usbip_queue;
+static DECLARE_WORK(usbip_work, event_handler);
+
+int usbip_init_eh(void)
+{
+	usbip_queue = create_singlethread_workqueue(WORK_QUEUE_NAME);
+	if (usbip_queue == NULL) {
+		pr_err("failed to create usbip_event\n");
+		return -ENOMEM;
+	}
+	return 0;
+}
+
+void usbip_finish_eh(void)
+{
+	flush_workqueue(usbip_queue);
+	destroy_workqueue(usbip_queue);
+	usbip_queue = NULL;
+}
+
+void usbip_event_add(struct usbip_device *ud, unsigned long event)
+{
+	struct usbip_event *ue;
+	unsigned long flags;
+
+	if (ud->event & USBIP_EH_BYE)
+		return;
+
+	set_event(ud, event);
+
+	spin_lock_irqsave(&event_lock, flags);
+
+	list_for_each_entry_reverse(ue, &event_list, node) {
+		if (ue->ud == ud)
+			goto out;
+	}
+
+	ue = kmalloc(sizeof(struct usbip_event), GFP_ATOMIC);
+	if (ue == NULL)
+		goto out;
+
+	ue->ud = ud;
+
+	list_add_tail(&ue->node, &event_list);
+	queue_work(usbip_queue, &usbip_work);
+
+out:
+	spin_unlock_irqrestore(&event_lock, flags);
+}
+EXPORT_SYMBOL_GPL(usbip_event_add);
+
+int usbip_event_happened(struct usbip_device *ud)
+{
+	int happened = 0;
+	unsigned long flags;
+
+	spin_lock_irqsave(&ud->lock, flags);
+	if (ud->event != 0)
+		happened = 1;
+	spin_unlock_irqrestore(&ud->lock, flags);
+
+	return happened;
+}
+EXPORT_SYMBOL_GPL(usbip_event_happened);
+
+int usbip_in_eh(struct task_struct *task)
+{
+	if (task == worker_context)
+		return 1;
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(usbip_in_eh);
diff --git a/drivers/usb/usbip/vhci.h b/drivers/usb/usbip/vhci.h
new file mode 100644
index 000000000..5659dce15
--- /dev/null
+++ b/drivers/usb/usbip/vhci.h
@@ -0,0 +1,174 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (C) 2003-2008 Takahiro Hirofuchi
+ * Copyright (C) 2015 Nobuo Iwata
+ */
+
+#ifndef __USBIP_VHCI_H
+#define __USBIP_VHCI_H
+
+#include <linux/device.h>
+#include <linux/list.h>
+#include <linux/spinlock.h>
+#include <linux/sysfs.h>
+#include <linux/types.h>
+#include <linux/usb.h>
+#include <linux/usb/hcd.h>
+#include <linux/wait.h>
+
+struct vhci_device {
+	struct usb_device *udev;
+
+	/*
+	 * devid specifies a remote usb device uniquely instead
+	 * of combination of busnum and devnum.
+	 */
+	__u32 devid;
+
+	/* speed of a remote device */
+	enum usb_device_speed speed;
+
+	/* vhci root-hub port to which this device is attached */
+	__u32 rhport;
+
+	struct usbip_device ud;
+
+	/* lock for the below link lists */
+	spinlock_t priv_lock;
+
+	/* vhci_priv is linked to one of them. */
+	struct list_head priv_tx;
+	struct list_head priv_rx;
+
+	/* vhci_unlink is linked to one of them */
+	struct list_head unlink_tx;
+	struct list_head unlink_rx;
+
+	/* vhci_tx thread sleeps for this queue */
+	wait_queue_head_t waitq_tx;
+};
+
+/* urb->hcpriv, use container_of() */
+struct vhci_priv {
+	unsigned long seqnum;
+	struct list_head list;
+
+	struct vhci_device *vdev;
+	struct urb *urb;
+};
+
+struct vhci_unlink {
+	/* seqnum of this request */
+	unsigned long seqnum;
+
+	struct list_head list;
+
+	/* seqnum of the unlink target */
+	unsigned long unlink_seqnum;
+};
+
+enum hub_speed {
+	HUB_SPEED_HIGH = 0,
+	HUB_SPEED_SUPER,
+};
+
+/* Number of supported ports. Value has an upperbound of USB_MAXCHILDREN */
+#ifdef CONFIG_USBIP_VHCI_HC_PORTS
+#define VHCI_HC_PORTS CONFIG_USBIP_VHCI_HC_PORTS
+#else
+#define VHCI_HC_PORTS 8
+#endif
+
+/* Each VHCI has 2 hubs (USB2 and USB3), each has VHCI_HC_PORTS ports */
+#define VHCI_PORTS	(VHCI_HC_PORTS*2)
+
+#ifdef CONFIG_USBIP_VHCI_NR_HCS
+#define VHCI_NR_HCS CONFIG_USBIP_VHCI_NR_HCS
+#else
+#define VHCI_NR_HCS 1
+#endif
+
+#define MAX_STATUS_NAME 16
+
+struct vhci {
+	spinlock_t lock;
+
+	struct platform_device *pdev;
+
+	struct vhci_hcd *vhci_hcd_hs;
+	struct vhci_hcd *vhci_hcd_ss;
+};
+
+/* for usb_hcd.hcd_priv[0] */
+struct vhci_hcd {
+	struct vhci *vhci;
+
+	u32 port_status[VHCI_HC_PORTS];
+
+	unsigned resuming:1;
+	unsigned long re_timeout;
+
+	atomic_t seqnum;
+
+	/*
+	 * NOTE:
+	 * wIndex shows the port number and begins from 1.
+	 * But, the index of this array begins from 0.
+	 */
+	struct vhci_device vdev[VHCI_HC_PORTS];
+};
+
+extern int vhci_num_controllers;
+extern struct vhci *vhcis;
+extern struct attribute_group vhci_attr_group;
+
+/* vhci_hcd.c */
+void rh_port_connect(struct vhci_device *vdev, enum usb_device_speed speed);
+
+/* vhci_sysfs.c */
+int vhci_init_attr_group(void);
+void vhci_finish_attr_group(void);
+
+/* vhci_rx.c */
+struct urb *pickup_urb_and_free_priv(struct vhci_device *vdev, __u32 seqnum);
+int vhci_rx_loop(void *data);
+
+/* vhci_tx.c */
+int vhci_tx_loop(void *data);
+
+static inline __u32 port_to_rhport(__u32 port)
+{
+	return port % VHCI_HC_PORTS;
+}
+
+static inline int port_to_pdev_nr(__u32 port)
+{
+	return port / VHCI_PORTS;
+}
+
+static inline struct vhci_hcd *hcd_to_vhci_hcd(struct usb_hcd *hcd)
+{
+	return (struct vhci_hcd *) (hcd->hcd_priv);
+}
+
+static inline struct device *hcd_dev(struct usb_hcd *hcd)
+{
+	return (hcd)->self.controller;
+}
+
+static inline const char *hcd_name(struct usb_hcd *hcd)
+{
+	return (hcd)->self.bus_name;
+}
+
+static inline struct usb_hcd *vhci_hcd_to_hcd(struct vhci_hcd *vhci_hcd)
+{
+	return container_of((void *) vhci_hcd, struct usb_hcd, hcd_priv);
+}
+
+static inline struct vhci_hcd *vdev_to_vhci_hcd(struct vhci_device *vdev)
+{
+	return container_of((void *)(vdev - vdev->rhport), struct vhci_hcd, vdev);
+}
+
+#endif /* __USBIP_VHCI_H */
diff --git a/drivers/usb/usbip/vhci_hcd.c b/drivers/usb/usbip/vhci_hcd.c
new file mode 100644
index 000000000..202dc76f7
--- /dev/null
+++ b/drivers/usb/usbip/vhci_hcd.c
@@ -0,0 +1,1607 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (C) 2003-2008 Takahiro Hirofuchi
+ * Copyright (C) 2015-2016 Nobuo Iwata
+ */
+
+#include <linux/init.h>
+#include <linux/file.h>
+#include <linux/kernel.h>
+#include <linux/kthread.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+
+#include "usbip_common.h"
+#include "vhci.h"
+
+#define DRIVER_AUTHOR "Takahiro Hirofuchi"
+#define DRIVER_DESC "USB/IP 'Virtual' Host Controller (VHCI) Driver"
+
+/*
+ * TODO
+ *	- update root hub emulation
+ *	- move the emulation code to userland ?
+ *		porting to other operating systems
+ *		minimize kernel code
+ *	- add suspend/resume code
+ *	- clean up everything
+ */
+
+/* See usb gadget dummy hcd */
+
+static int vhci_hub_status(struct usb_hcd *hcd, char *buff);
+static int vhci_hub_control(struct usb_hcd *hcd, u16 typeReq, u16 wValue,
+			    u16 wIndex, char *buff, u16 wLength);
+static int vhci_urb_enqueue(struct usb_hcd *hcd, struct urb *urb,
+			    gfp_t mem_flags);
+static int vhci_urb_dequeue(struct usb_hcd *hcd, struct urb *urb, int status);
+static int vhci_start(struct usb_hcd *vhci_hcd);
+static void vhci_stop(struct usb_hcd *hcd);
+static int vhci_get_frame_number(struct usb_hcd *hcd);
+
+static const char driver_name[] = "vhci_hcd";
+static const char driver_desc[] = "USB/IP Virtual Host Controller";
+
+int vhci_num_controllers = VHCI_NR_HCS;
+struct vhci *vhcis;
+
+static const char * const bit_desc[] = {
+	"CONNECTION",		/*0*/
+	"ENABLE",		/*1*/
+	"SUSPEND",		/*2*/
+	"OVER_CURRENT",		/*3*/
+	"RESET",		/*4*/
+	"L1",			/*5*/
+	"R6",			/*6*/
+	"R7",			/*7*/
+	"POWER",		/*8*/
+	"LOWSPEED",		/*9*/
+	"HIGHSPEED",		/*10*/
+	"PORT_TEST",		/*11*/
+	"INDICATOR",		/*12*/
+	"R13",			/*13*/
+	"R14",			/*14*/
+	"R15",			/*15*/
+	"C_CONNECTION",		/*16*/
+	"C_ENABLE",		/*17*/
+	"C_SUSPEND",		/*18*/
+	"C_OVER_CURRENT",	/*19*/
+	"C_RESET",		/*20*/
+	"C_L1",			/*21*/
+	"R22",			/*22*/
+	"R23",			/*23*/
+	"R24",			/*24*/
+	"R25",			/*25*/
+	"R26",			/*26*/
+	"R27",			/*27*/
+	"R28",			/*28*/
+	"R29",			/*29*/
+	"R30",			/*30*/
+	"R31",			/*31*/
+};
+
+static const char * const bit_desc_ss[] = {
+	"CONNECTION",		/*0*/
+	"ENABLE",		/*1*/
+	"SUSPEND",		/*2*/
+	"OVER_CURRENT",		/*3*/
+	"RESET",		/*4*/
+	"L1",			/*5*/
+	"R6",			/*6*/
+	"R7",			/*7*/
+	"R8",			/*8*/
+	"POWER",		/*9*/
+	"HIGHSPEED",		/*10*/
+	"PORT_TEST",		/*11*/
+	"INDICATOR",		/*12*/
+	"R13",			/*13*/
+	"R14",			/*14*/
+	"R15",			/*15*/
+	"C_CONNECTION",		/*16*/
+	"C_ENABLE",		/*17*/
+	"C_SUSPEND",		/*18*/
+	"C_OVER_CURRENT",	/*19*/
+	"C_RESET",		/*20*/
+	"C_BH_RESET",		/*21*/
+	"C_LINK_STATE",		/*22*/
+	"C_CONFIG_ERROR",	/*23*/
+	"R24",			/*24*/
+	"R25",			/*25*/
+	"R26",			/*26*/
+	"R27",			/*27*/
+	"R28",			/*28*/
+	"R29",			/*29*/
+	"R30",			/*30*/
+	"R31",			/*31*/
+};
+
+static void dump_port_status_diff(u32 prev_status, u32 new_status, bool usb3)
+{
+	int i = 0;
+	u32 bit = 1;
+	const char * const *desc = bit_desc;
+
+	if (usb3)
+		desc = bit_desc_ss;
+
+	pr_debug("status prev -> new: %08x -> %08x\n", prev_status, new_status);
+	while (bit) {
+		u32 prev = prev_status & bit;
+		u32 new = new_status & bit;
+		char change;
+
+		if (!prev && new)
+			change = '+';
+		else if (prev && !new)
+			change = '-';
+		else
+			change = ' ';
+
+		if (prev || new) {
+			pr_debug(" %c%s\n", change, desc[i]);
+
+			if (bit == 1) /* USB_PORT_STAT_CONNECTION */
+				pr_debug(" %c%s\n", change, "USB_PORT_STAT_SPEED_5GBPS");
+		}
+		bit <<= 1;
+		i++;
+	}
+	pr_debug("\n");
+}
+
+void rh_port_connect(struct vhci_device *vdev, enum usb_device_speed speed)
+{
+	struct vhci_hcd	*vhci_hcd = vdev_to_vhci_hcd(vdev);
+	struct vhci *vhci = vhci_hcd->vhci;
+	int		rhport = vdev->rhport;
+	u32		status;
+	unsigned long	flags;
+
+	usbip_dbg_vhci_rh("rh_port_connect %d\n", rhport);
+
+	spin_lock_irqsave(&vhci->lock, flags);
+
+	status = vhci_hcd->port_status[rhport];
+
+	status |= USB_PORT_STAT_CONNECTION | (1 << USB_PORT_FEAT_C_CONNECTION);
+
+	switch (speed) {
+	case USB_SPEED_HIGH:
+		status |= USB_PORT_STAT_HIGH_SPEED;
+		break;
+	case USB_SPEED_LOW:
+		status |= USB_PORT_STAT_LOW_SPEED;
+		break;
+	default:
+		break;
+	}
+
+	vhci_hcd->port_status[rhport] = status;
+
+	spin_unlock_irqrestore(&vhci->lock, flags);
+
+	usb_hcd_poll_rh_status(vhci_hcd_to_hcd(vhci_hcd));
+}
+
+static void rh_port_disconnect(struct vhci_device *vdev)
+{
+	struct vhci_hcd	*vhci_hcd = vdev_to_vhci_hcd(vdev);
+	struct vhci *vhci = vhci_hcd->vhci;
+	int		rhport = vdev->rhport;
+	u32		status;
+	unsigned long	flags;
+
+	usbip_dbg_vhci_rh("rh_port_disconnect %d\n", rhport);
+
+	spin_lock_irqsave(&vhci->lock, flags);
+
+	status = vhci_hcd->port_status[rhport];
+
+	status &= ~USB_PORT_STAT_CONNECTION;
+	status |= (1 << USB_PORT_FEAT_C_CONNECTION);
+
+	vhci_hcd->port_status[rhport] = status;
+
+	spin_unlock_irqrestore(&vhci->lock, flags);
+	usb_hcd_poll_rh_status(vhci_hcd_to_hcd(vhci_hcd));
+}
+
+#define PORT_C_MASK				\
+	((USB_PORT_STAT_C_CONNECTION		\
+	  | USB_PORT_STAT_C_ENABLE		\
+	  | USB_PORT_STAT_C_SUSPEND		\
+	  | USB_PORT_STAT_C_OVERCURRENT		\
+	  | USB_PORT_STAT_C_RESET) << 16)
+
+/*
+ * Returns 0 if the status hasn't changed, or the number of bytes in buf.
+ * Ports are 0-indexed from the HCD point of view,
+ * and 1-indexed from the USB core pointer of view.
+ *
+ * @buf: a bitmap to show which port status has been changed.
+ *  bit  0: reserved
+ *  bit  1: the status of port 0 has been changed.
+ *  bit  2: the status of port 1 has been changed.
+ *  ...
+ */
+static int vhci_hub_status(struct usb_hcd *hcd, char *buf)
+{
+	struct vhci_hcd	*vhci_hcd = hcd_to_vhci_hcd(hcd);
+	struct vhci *vhci = vhci_hcd->vhci;
+	int		retval = DIV_ROUND_UP(VHCI_HC_PORTS + 1, 8);
+	int		rhport;
+	int		changed = 0;
+	unsigned long	flags;
+
+	memset(buf, 0, retval);
+
+	spin_lock_irqsave(&vhci->lock, flags);
+	if (!HCD_HW_ACCESSIBLE(hcd)) {
+		usbip_dbg_vhci_rh("hw accessible flag not on?\n");
+		goto done;
+	}
+
+	/* check pseudo status register for each port */
+	for (rhport = 0; rhport < VHCI_HC_PORTS; rhport++) {
+		if ((vhci_hcd->port_status[rhport] & PORT_C_MASK)) {
+			/* The status of a port has been changed, */
+			usbip_dbg_vhci_rh("port %d status changed\n", rhport);
+
+			buf[(rhport + 1) / 8] |= 1 << (rhport + 1) % 8;
+			changed = 1;
+		}
+	}
+
+	if ((hcd->state == HC_STATE_SUSPENDED) && (changed == 1))
+		usb_hcd_resume_root_hub(hcd);
+
+done:
+	spin_unlock_irqrestore(&vhci->lock, flags);
+	return changed ? retval : 0;
+}
+
+/* usb 3.0 root hub device descriptor */
+static struct {
+	struct usb_bos_descriptor bos;
+	struct usb_ss_cap_descriptor ss_cap;
+} __packed usb3_bos_desc = {
+
+	.bos = {
+		.bLength		= USB_DT_BOS_SIZE,
+		.bDescriptorType	= USB_DT_BOS,
+		.wTotalLength		= cpu_to_le16(sizeof(usb3_bos_desc)),
+		.bNumDeviceCaps		= 1,
+	},
+	.ss_cap = {
+		.bLength		= USB_DT_USB_SS_CAP_SIZE,
+		.bDescriptorType	= USB_DT_DEVICE_CAPABILITY,
+		.bDevCapabilityType	= USB_SS_CAP_TYPE,
+		.wSpeedSupported	= cpu_to_le16(USB_5GBPS_OPERATION),
+		.bFunctionalitySupport	= ilog2(USB_5GBPS_OPERATION),
+	},
+};
+
+static inline void
+ss_hub_descriptor(struct usb_hub_descriptor *desc)
+{
+	memset(desc, 0, sizeof *desc);
+	desc->bDescriptorType = USB_DT_SS_HUB;
+	desc->bDescLength = 12;
+	desc->wHubCharacteristics = cpu_to_le16(
+		HUB_CHAR_INDV_PORT_LPSM | HUB_CHAR_COMMON_OCPM);
+	desc->bNbrPorts = VHCI_HC_PORTS;
+	desc->u.ss.bHubHdrDecLat = 0x04; /* Worst case: 0.4 micro sec*/
+	desc->u.ss.DeviceRemovable = 0xffff;
+}
+
+static inline void hub_descriptor(struct usb_hub_descriptor *desc)
+{
+	int width;
+
+	memset(desc, 0, sizeof(*desc));
+	desc->bDescriptorType = USB_DT_HUB;
+	desc->wHubCharacteristics = cpu_to_le16(
+		HUB_CHAR_INDV_PORT_LPSM | HUB_CHAR_COMMON_OCPM);
+
+	desc->bNbrPorts = VHCI_HC_PORTS;
+	BUILD_BUG_ON(VHCI_HC_PORTS > USB_MAXCHILDREN);
+	width = desc->bNbrPorts / 8 + 1;
+	desc->bDescLength = USB_DT_HUB_NONVAR_SIZE + 2 * width;
+	memset(&desc->u.hs.DeviceRemovable[0], 0, width);
+	memset(&desc->u.hs.DeviceRemovable[width], 0xff, width);
+}
+
+static int vhci_hub_control(struct usb_hcd *hcd, u16 typeReq, u16 wValue,
+			    u16 wIndex, char *buf, u16 wLength)
+{
+	struct vhci_hcd	*vhci_hcd;
+	struct vhci	*vhci;
+	int             retval = 0;
+	int		rhport = -1;
+	unsigned long	flags;
+	bool invalid_rhport = false;
+
+	u32 prev_port_status[VHCI_HC_PORTS];
+
+	if (!HCD_HW_ACCESSIBLE(hcd))
+		return -ETIMEDOUT;
+
+	/*
+	 * NOTE:
+	 * wIndex (bits 0-7) shows the port number and begins from 1?
+	 */
+	wIndex = ((__u8)(wIndex & 0x00ff));
+	usbip_dbg_vhci_rh("typeReq %x wValue %x wIndex %x\n", typeReq, wValue,
+			  wIndex);
+
+	/*
+	 * wIndex can be 0 for some request types (typeReq). rhport is
+	 * in valid range when wIndex >= 1 and < VHCI_HC_PORTS.
+	 *
+	 * Reference port_status[] only with valid rhport when
+	 * invalid_rhport is false.
+	 */
+	if (wIndex < 1 || wIndex > VHCI_HC_PORTS) {
+		invalid_rhport = true;
+		if (wIndex > VHCI_HC_PORTS)
+			pr_err("invalid port number %d\n", wIndex);
+	} else
+		rhport = wIndex - 1;
+
+	vhci_hcd = hcd_to_vhci_hcd(hcd);
+	vhci = vhci_hcd->vhci;
+
+	spin_lock_irqsave(&vhci->lock, flags);
+
+	/* store old status and compare now and old later */
+	if (usbip_dbg_flag_vhci_rh) {
+		if (!invalid_rhport)
+			memcpy(prev_port_status, vhci_hcd->port_status,
+				sizeof(prev_port_status));
+	}
+
+	switch (typeReq) {
+	case ClearHubFeature:
+		usbip_dbg_vhci_rh(" ClearHubFeature\n");
+		break;
+	case ClearPortFeature:
+		if (invalid_rhport) {
+			pr_err("invalid port number %d\n", wIndex);
+			goto error;
+		}
+		switch (wValue) {
+		case USB_PORT_FEAT_SUSPEND:
+			if (hcd->speed == HCD_USB3) {
+				pr_err(" ClearPortFeature: USB_PORT_FEAT_SUSPEND req not "
+				       "supported for USB 3.0 roothub\n");
+				goto error;
+			}
+			usbip_dbg_vhci_rh(
+				" ClearPortFeature: USB_PORT_FEAT_SUSPEND\n");
+			if (vhci_hcd->port_status[rhport] & USB_PORT_STAT_SUSPEND) {
+				/* 20msec signaling */
+				vhci_hcd->resuming = 1;
+				vhci_hcd->re_timeout = jiffies + msecs_to_jiffies(20);
+			}
+			break;
+		case USB_PORT_FEAT_POWER:
+			usbip_dbg_vhci_rh(
+				" ClearPortFeature: USB_PORT_FEAT_POWER\n");
+			if (hcd->speed == HCD_USB3)
+				vhci_hcd->port_status[rhport] &= ~USB_SS_PORT_STAT_POWER;
+			else
+				vhci_hcd->port_status[rhport] &= ~USB_PORT_STAT_POWER;
+			break;
+		default:
+			usbip_dbg_vhci_rh(" ClearPortFeature: default %x\n",
+					  wValue);
+			if (wValue >= 32)
+				goto error;
+			vhci_hcd->port_status[rhport] &= ~(1 << wValue);
+			break;
+		}
+		break;
+	case GetHubDescriptor:
+		usbip_dbg_vhci_rh(" GetHubDescriptor\n");
+		if (hcd->speed == HCD_USB3 &&
+				(wLength < USB_DT_SS_HUB_SIZE ||
+				 wValue != (USB_DT_SS_HUB << 8))) {
+			pr_err("Wrong hub descriptor type for USB 3.0 roothub.\n");
+			goto error;
+		}
+		if (hcd->speed == HCD_USB3)
+			ss_hub_descriptor((struct usb_hub_descriptor *) buf);
+		else
+			hub_descriptor((struct usb_hub_descriptor *) buf);
+		break;
+	case DeviceRequest | USB_REQ_GET_DESCRIPTOR:
+		if (hcd->speed != HCD_USB3)
+			goto error;
+
+		if ((wValue >> 8) != USB_DT_BOS)
+			goto error;
+
+		memcpy(buf, &usb3_bos_desc, sizeof(usb3_bos_desc));
+		retval = sizeof(usb3_bos_desc);
+		break;
+	case GetHubStatus:
+		usbip_dbg_vhci_rh(" GetHubStatus\n");
+		*(__le32 *) buf = cpu_to_le32(0);
+		break;
+	case GetPortStatus:
+		usbip_dbg_vhci_rh(" GetPortStatus port %x\n", wIndex);
+		if (invalid_rhport) {
+			pr_err("invalid port number %d\n", wIndex);
+			retval = -EPIPE;
+			goto error;
+		}
+
+		/* we do not care about resume. */
+
+		/* whoever resets or resumes must GetPortStatus to
+		 * complete it!!
+		 */
+		if (vhci_hcd->resuming && time_after(jiffies, vhci_hcd->re_timeout)) {
+			vhci_hcd->port_status[rhport] |= (1 << USB_PORT_FEAT_C_SUSPEND);
+			vhci_hcd->port_status[rhport] &= ~(1 << USB_PORT_FEAT_SUSPEND);
+			vhci_hcd->resuming = 0;
+			vhci_hcd->re_timeout = 0;
+		}
+
+		if ((vhci_hcd->port_status[rhport] & (1 << USB_PORT_FEAT_RESET)) !=
+		    0 && time_after(jiffies, vhci_hcd->re_timeout)) {
+			vhci_hcd->port_status[rhport] |= (1 << USB_PORT_FEAT_C_RESET);
+			vhci_hcd->port_status[rhport] &= ~(1 << USB_PORT_FEAT_RESET);
+			vhci_hcd->re_timeout = 0;
+
+			/*
+			 * A few drivers do usb reset during probe when
+			 * the device could be in VDEV_ST_USED state
+			 */
+			if (vhci_hcd->vdev[rhport].ud.status ==
+				VDEV_ST_NOTASSIGNED ||
+			    vhci_hcd->vdev[rhport].ud.status ==
+				VDEV_ST_USED) {
+				usbip_dbg_vhci_rh(
+					" enable rhport %d (status %u)\n",
+					rhport,
+					vhci_hcd->vdev[rhport].ud.status);
+				vhci_hcd->port_status[rhport] |=
+					USB_PORT_STAT_ENABLE;
+			}
+
+			if (hcd->speed < HCD_USB3) {
+				switch (vhci_hcd->vdev[rhport].speed) {
+				case USB_SPEED_HIGH:
+					vhci_hcd->port_status[rhport] |=
+					      USB_PORT_STAT_HIGH_SPEED;
+					break;
+				case USB_SPEED_LOW:
+					vhci_hcd->port_status[rhport] |=
+						USB_PORT_STAT_LOW_SPEED;
+					break;
+				default:
+					pr_err("vhci_device speed not set\n");
+					break;
+				}
+			}
+		}
+		((__le16 *) buf)[0] = cpu_to_le16(vhci_hcd->port_status[rhport]);
+		((__le16 *) buf)[1] =
+			cpu_to_le16(vhci_hcd->port_status[rhport] >> 16);
+
+		usbip_dbg_vhci_rh(" GetPortStatus bye %x %x\n", ((u16 *)buf)[0],
+				  ((u16 *)buf)[1]);
+		break;
+	case SetHubFeature:
+		usbip_dbg_vhci_rh(" SetHubFeature\n");
+		retval = -EPIPE;
+		break;
+	case SetPortFeature:
+		switch (wValue) {
+		case USB_PORT_FEAT_LINK_STATE:
+			usbip_dbg_vhci_rh(
+				" SetPortFeature: USB_PORT_FEAT_LINK_STATE\n");
+			if (hcd->speed != HCD_USB3) {
+				pr_err("USB_PORT_FEAT_LINK_STATE req not "
+				       "supported for USB 2.0 roothub\n");
+				goto error;
+			}
+			/*
+			 * Since this is dummy we don't have an actual link so
+			 * there is nothing to do for the SET_LINK_STATE cmd
+			 */
+			break;
+		case USB_PORT_FEAT_U1_TIMEOUT:
+			usbip_dbg_vhci_rh(
+				" SetPortFeature: USB_PORT_FEAT_U1_TIMEOUT\n");
+		case USB_PORT_FEAT_U2_TIMEOUT:
+			usbip_dbg_vhci_rh(
+				" SetPortFeature: USB_PORT_FEAT_U2_TIMEOUT\n");
+			/* TODO: add suspend/resume support! */
+			if (hcd->speed != HCD_USB3) {
+				pr_err("USB_PORT_FEAT_U1/2_TIMEOUT req not "
+				       "supported for USB 2.0 roothub\n");
+				goto error;
+			}
+			break;
+		case USB_PORT_FEAT_SUSPEND:
+			usbip_dbg_vhci_rh(
+				" SetPortFeature: USB_PORT_FEAT_SUSPEND\n");
+			/* Applicable only for USB2.0 hub */
+			if (hcd->speed == HCD_USB3) {
+				pr_err("USB_PORT_FEAT_SUSPEND req not "
+				       "supported for USB 3.0 roothub\n");
+				goto error;
+			}
+
+			if (invalid_rhport) {
+				pr_err("invalid port number %d\n", wIndex);
+				goto error;
+			}
+
+			vhci_hcd->port_status[rhport] |= USB_PORT_STAT_SUSPEND;
+			break;
+		case USB_PORT_FEAT_POWER:
+			usbip_dbg_vhci_rh(
+				" SetPortFeature: USB_PORT_FEAT_POWER\n");
+			if (invalid_rhport) {
+				pr_err("invalid port number %d\n", wIndex);
+				goto error;
+			}
+			if (hcd->speed == HCD_USB3)
+				vhci_hcd->port_status[rhport] |= USB_SS_PORT_STAT_POWER;
+			else
+				vhci_hcd->port_status[rhport] |= USB_PORT_STAT_POWER;
+			break;
+		case USB_PORT_FEAT_BH_PORT_RESET:
+			usbip_dbg_vhci_rh(
+				" SetPortFeature: USB_PORT_FEAT_BH_PORT_RESET\n");
+			if (invalid_rhport) {
+				pr_err("invalid port number %d\n", wIndex);
+				goto error;
+			}
+			/* Applicable only for USB3.0 hub */
+			if (hcd->speed != HCD_USB3) {
+				pr_err("USB_PORT_FEAT_BH_PORT_RESET req not "
+				       "supported for USB 2.0 roothub\n");
+				goto error;
+			}
+			/* FALLS THROUGH */
+		case USB_PORT_FEAT_RESET:
+			usbip_dbg_vhci_rh(
+				" SetPortFeature: USB_PORT_FEAT_RESET\n");
+			if (invalid_rhport) {
+				pr_err("invalid port number %d\n", wIndex);
+				goto error;
+			}
+			/* if it's already enabled, disable */
+			if (hcd->speed == HCD_USB3) {
+				vhci_hcd->port_status[rhport] = 0;
+				vhci_hcd->port_status[rhport] =
+					(USB_SS_PORT_STAT_POWER |
+					 USB_PORT_STAT_CONNECTION |
+					 USB_PORT_STAT_RESET);
+			} else if (vhci_hcd->port_status[rhport] & USB_PORT_STAT_ENABLE) {
+				vhci_hcd->port_status[rhport] &= ~(USB_PORT_STAT_ENABLE
+					| USB_PORT_STAT_LOW_SPEED
+					| USB_PORT_STAT_HIGH_SPEED);
+			}
+
+			/* 50msec reset signaling */
+			vhci_hcd->re_timeout = jiffies + msecs_to_jiffies(50);
+
+			/* FALLS THROUGH */
+		default:
+			usbip_dbg_vhci_rh(" SetPortFeature: default %d\n",
+					  wValue);
+			if (invalid_rhport) {
+				pr_err("invalid port number %d\n", wIndex);
+				goto error;
+			}
+			if (wValue >= 32)
+				goto error;
+			if (hcd->speed == HCD_USB3) {
+				if ((vhci_hcd->port_status[rhport] &
+				     USB_SS_PORT_STAT_POWER) != 0) {
+					vhci_hcd->port_status[rhport] |= (1 << wValue);
+				}
+			} else
+				if ((vhci_hcd->port_status[rhport] &
+				     USB_PORT_STAT_POWER) != 0) {
+					vhci_hcd->port_status[rhport] |= (1 << wValue);
+				}
+		}
+		break;
+	case GetPortErrorCount:
+		usbip_dbg_vhci_rh(" GetPortErrorCount\n");
+		if (hcd->speed != HCD_USB3) {
+			pr_err("GetPortErrorCount req not "
+			       "supported for USB 2.0 roothub\n");
+			goto error;
+		}
+		/* We'll always return 0 since this is a dummy hub */
+		*(__le32 *) buf = cpu_to_le32(0);
+		break;
+	case SetHubDepth:
+		usbip_dbg_vhci_rh(" SetHubDepth\n");
+		if (hcd->speed != HCD_USB3) {
+			pr_err("SetHubDepth req not supported for "
+			       "USB 2.0 roothub\n");
+			goto error;
+		}
+		break;
+	default:
+		pr_err("default hub control req: %04x v%04x i%04x l%d\n",
+			typeReq, wValue, wIndex, wLength);
+error:
+		/* "protocol stall" on error */
+		retval = -EPIPE;
+	}
+
+	if (usbip_dbg_flag_vhci_rh) {
+		pr_debug("port %d\n", rhport);
+		/* Only dump valid port status */
+		if (!invalid_rhport) {
+			dump_port_status_diff(prev_port_status[rhport],
+					      vhci_hcd->port_status[rhport],
+					      hcd->speed == HCD_USB3);
+		}
+	}
+	usbip_dbg_vhci_rh(" bye\n");
+
+	spin_unlock_irqrestore(&vhci->lock, flags);
+
+	if (!invalid_rhport &&
+	    (vhci_hcd->port_status[rhport] & PORT_C_MASK) != 0) {
+		usb_hcd_poll_rh_status(hcd);
+	}
+
+	return retval;
+}
+
+static void vhci_tx_urb(struct urb *urb, struct vhci_device *vdev)
+{
+	struct vhci_priv *priv;
+	struct vhci_hcd *vhci_hcd;
+	unsigned long flags;
+
+	if (!vdev) {
+		pr_err("could not get virtual device");
+		return;
+	}
+	vhci_hcd = vdev_to_vhci_hcd(vdev);
+
+	priv = kzalloc(sizeof(struct vhci_priv), GFP_ATOMIC);
+	if (!priv) {
+		usbip_event_add(&vdev->ud, VDEV_EVENT_ERROR_MALLOC);
+		return;
+	}
+
+	spin_lock_irqsave(&vdev->priv_lock, flags);
+
+	priv->seqnum = atomic_inc_return(&vhci_hcd->seqnum);
+	if (priv->seqnum == 0xffff)
+		dev_info(&urb->dev->dev, "seqnum max\n");
+
+	priv->vdev = vdev;
+	priv->urb = urb;
+
+	urb->hcpriv = (void *) priv;
+
+	list_add_tail(&priv->list, &vdev->priv_tx);
+
+	wake_up(&vdev->waitq_tx);
+	spin_unlock_irqrestore(&vdev->priv_lock, flags);
+}
+
+static int vhci_urb_enqueue(struct usb_hcd *hcd, struct urb *urb, gfp_t mem_flags)
+{
+	struct vhci_hcd *vhci_hcd = hcd_to_vhci_hcd(hcd);
+	struct vhci *vhci = vhci_hcd->vhci;
+	struct device *dev = &urb->dev->dev;
+	u8 portnum = urb->dev->portnum;
+	int ret = 0;
+	struct vhci_device *vdev;
+	unsigned long flags;
+
+	if (portnum > VHCI_HC_PORTS) {
+		pr_err("invalid port number %d\n", portnum);
+		return -ENODEV;
+	}
+	vdev = &vhci_hcd->vdev[portnum-1];
+
+	if (!urb->transfer_buffer && !urb->num_sgs &&
+	     urb->transfer_buffer_length) {
+		dev_dbg(dev, "Null URB transfer buffer\n");
+		return -EINVAL;
+	}
+
+	spin_lock_irqsave(&vhci->lock, flags);
+
+	if (urb->status != -EINPROGRESS) {
+		dev_err(dev, "URB already unlinked!, status %d\n", urb->status);
+		spin_unlock_irqrestore(&vhci->lock, flags);
+		return urb->status;
+	}
+
+	/* refuse enqueue for dead connection */
+	spin_lock(&vdev->ud.lock);
+	if (vdev->ud.status == VDEV_ST_NULL ||
+	    vdev->ud.status == VDEV_ST_ERROR) {
+		dev_err(dev, "enqueue for inactive port %d\n", vdev->rhport);
+		spin_unlock(&vdev->ud.lock);
+		spin_unlock_irqrestore(&vhci->lock, flags);
+		return -ENODEV;
+	}
+	spin_unlock(&vdev->ud.lock);
+
+	ret = usb_hcd_link_urb_to_ep(hcd, urb);
+	if (ret)
+		goto no_need_unlink;
+
+	/*
+	 * The enumeration process is as follows;
+	 *
+	 *  1. Get_Descriptor request to DevAddrs(0) EndPoint(0)
+	 *     to get max packet length of default pipe
+	 *
+	 *  2. Set_Address request to DevAddr(0) EndPoint(0)
+	 *
+	 */
+	if (usb_pipedevice(urb->pipe) == 0) {
+		__u8 type = usb_pipetype(urb->pipe);
+		struct usb_ctrlrequest *ctrlreq =
+			(struct usb_ctrlrequest *) urb->setup_packet;
+
+		if (type != PIPE_CONTROL || !ctrlreq) {
+			dev_err(dev, "invalid request to devnum 0\n");
+			ret = -EINVAL;
+			goto no_need_xmit;
+		}
+
+		switch (ctrlreq->bRequest) {
+		case USB_REQ_SET_ADDRESS:
+			/* set_address may come when a device is reset */
+			dev_info(dev, "SetAddress Request (%d) to port %d\n",
+				 ctrlreq->wValue, vdev->rhport);
+
+			usb_put_dev(vdev->udev);
+			vdev->udev = usb_get_dev(urb->dev);
+
+			spin_lock(&vdev->ud.lock);
+			vdev->ud.status = VDEV_ST_USED;
+			spin_unlock(&vdev->ud.lock);
+
+			if (urb->status == -EINPROGRESS) {
+				/* This request is successfully completed. */
+				/* If not -EINPROGRESS, possibly unlinked. */
+				urb->status = 0;
+			}
+
+			goto no_need_xmit;
+
+		case USB_REQ_GET_DESCRIPTOR:
+			if (ctrlreq->wValue == cpu_to_le16(USB_DT_DEVICE << 8))
+				usbip_dbg_vhci_hc(
+					"Not yet?:Get_Descriptor to device 0 (get max pipe size)\n");
+
+			usb_put_dev(vdev->udev);
+			vdev->udev = usb_get_dev(urb->dev);
+			goto out;
+
+		default:
+			/* NOT REACHED */
+			dev_err(dev,
+				"invalid request to devnum 0 bRequest %u, wValue %u\n",
+				ctrlreq->bRequest,
+				ctrlreq->wValue);
+			ret =  -EINVAL;
+			goto no_need_xmit;
+		}
+
+	}
+
+out:
+	vhci_tx_urb(urb, vdev);
+	spin_unlock_irqrestore(&vhci->lock, flags);
+
+	return 0;
+
+no_need_xmit:
+	usb_hcd_unlink_urb_from_ep(hcd, urb);
+no_need_unlink:
+	spin_unlock_irqrestore(&vhci->lock, flags);
+	if (!ret)
+		usb_hcd_giveback_urb(hcd, urb, urb->status);
+	return ret;
+}
+
+/*
+ * vhci_rx gives back the urb after receiving the reply of the urb.  If an
+ * unlink pdu is sent or not, vhci_rx receives a normal return pdu and gives
+ * back its urb. For the driver unlinking the urb, the content of the urb is
+ * not important, but the calling to its completion handler is important; the
+ * completion of unlinking is notified by the completion handler.
+ *
+ *
+ * CLIENT SIDE
+ *
+ * - When vhci_hcd receives RET_SUBMIT,
+ *
+ *	- case 1a). the urb of the pdu is not unlinking.
+ *		- normal case
+ *		=> just give back the urb
+ *
+ *	- case 1b). the urb of the pdu is unlinking.
+ *		- usbip.ko will return a reply of the unlinking request.
+ *		=> give back the urb now and go to case 2b).
+ *
+ * - When vhci_hcd receives RET_UNLINK,
+ *
+ *	- case 2a). a submit request is still pending in vhci_hcd.
+ *		- urb was really pending in usbip.ko and urb_unlink_urb() was
+ *		  completed there.
+ *		=> free a pending submit request
+ *		=> notify unlink completeness by giving back the urb
+ *
+ *	- case 2b). a submit request is *not* pending in vhci_hcd.
+ *		- urb was already given back to the core driver.
+ *		=> do not give back the urb
+ *
+ *
+ * SERVER SIDE
+ *
+ * - When usbip receives CMD_UNLINK,
+ *
+ *	- case 3a). the urb of the unlink request is now in submission.
+ *		=> do usb_unlink_urb().
+ *		=> after the unlink is completed, send RET_UNLINK.
+ *
+ *	- case 3b). the urb of the unlink request is not in submission.
+ *		- may be already completed or never be received
+ *		=> send RET_UNLINK
+ *
+ */
+static int vhci_urb_dequeue(struct usb_hcd *hcd, struct urb *urb, int status)
+{
+	struct vhci_hcd *vhci_hcd = hcd_to_vhci_hcd(hcd);
+	struct vhci *vhci = vhci_hcd->vhci;
+	struct vhci_priv *priv;
+	struct vhci_device *vdev;
+	unsigned long flags;
+
+	spin_lock_irqsave(&vhci->lock, flags);
+
+	priv = urb->hcpriv;
+	if (!priv) {
+		/* URB was never linked! or will be soon given back by
+		 * vhci_rx. */
+		spin_unlock_irqrestore(&vhci->lock, flags);
+		return -EIDRM;
+	}
+
+	{
+		int ret = 0;
+
+		ret = usb_hcd_check_unlink_urb(hcd, urb, status);
+		if (ret) {
+			spin_unlock_irqrestore(&vhci->lock, flags);
+			return ret;
+		}
+	}
+
+	 /* send unlink request here? */
+	vdev = priv->vdev;
+
+	if (!vdev->ud.tcp_socket) {
+		/* tcp connection is closed */
+		spin_lock(&vdev->priv_lock);
+
+		list_del(&priv->list);
+		kfree(priv);
+		urb->hcpriv = NULL;
+
+		spin_unlock(&vdev->priv_lock);
+
+		/*
+		 * If tcp connection is alive, we have sent CMD_UNLINK.
+		 * vhci_rx will receive RET_UNLINK and give back the URB.
+		 * Otherwise, we give back it here.
+		 */
+		usb_hcd_unlink_urb_from_ep(hcd, urb);
+
+		spin_unlock_irqrestore(&vhci->lock, flags);
+		usb_hcd_giveback_urb(hcd, urb, urb->status);
+		spin_lock_irqsave(&vhci->lock, flags);
+
+	} else {
+		/* tcp connection is alive */
+		struct vhci_unlink *unlink;
+
+		spin_lock(&vdev->priv_lock);
+
+		/* setup CMD_UNLINK pdu */
+		unlink = kzalloc(sizeof(struct vhci_unlink), GFP_ATOMIC);
+		if (!unlink) {
+			spin_unlock(&vdev->priv_lock);
+			spin_unlock_irqrestore(&vhci->lock, flags);
+			usbip_event_add(&vdev->ud, VDEV_EVENT_ERROR_MALLOC);
+			return -ENOMEM;
+		}
+
+		unlink->seqnum = atomic_inc_return(&vhci_hcd->seqnum);
+		if (unlink->seqnum == 0xffff)
+			pr_info("seqnum max\n");
+
+		unlink->unlink_seqnum = priv->seqnum;
+
+		/* send cmd_unlink and try to cancel the pending URB in the
+		 * peer */
+		list_add_tail(&unlink->list, &vdev->unlink_tx);
+		wake_up(&vdev->waitq_tx);
+
+		spin_unlock(&vdev->priv_lock);
+	}
+
+	spin_unlock_irqrestore(&vhci->lock, flags);
+
+	usbip_dbg_vhci_hc("leave\n");
+	return 0;
+}
+
+static void vhci_device_unlink_cleanup(struct vhci_device *vdev)
+{
+	struct vhci_hcd *vhci_hcd = vdev_to_vhci_hcd(vdev);
+	struct usb_hcd *hcd = vhci_hcd_to_hcd(vhci_hcd);
+	struct vhci *vhci = vhci_hcd->vhci;
+	struct vhci_unlink *unlink, *tmp;
+	unsigned long flags;
+
+	spin_lock_irqsave(&vhci->lock, flags);
+	spin_lock(&vdev->priv_lock);
+
+	list_for_each_entry_safe(unlink, tmp, &vdev->unlink_tx, list) {
+		struct urb *urb;
+
+		/* give back urb of unsent unlink request */
+		pr_info("unlink cleanup tx %lu\n", unlink->unlink_seqnum);
+
+		urb = pickup_urb_and_free_priv(vdev, unlink->unlink_seqnum);
+		if (!urb) {
+			list_del(&unlink->list);
+			kfree(unlink);
+			continue;
+		}
+
+		urb->status = -ENODEV;
+
+		usb_hcd_unlink_urb_from_ep(hcd, urb);
+
+		list_del(&unlink->list);
+
+		spin_unlock(&vdev->priv_lock);
+		spin_unlock_irqrestore(&vhci->lock, flags);
+
+		usb_hcd_giveback_urb(hcd, urb, urb->status);
+
+		spin_lock_irqsave(&vhci->lock, flags);
+		spin_lock(&vdev->priv_lock);
+
+		kfree(unlink);
+	}
+
+	while (!list_empty(&vdev->unlink_rx)) {
+		struct urb *urb;
+
+		unlink = list_first_entry(&vdev->unlink_rx, struct vhci_unlink,
+			list);
+
+		/* give back URB of unanswered unlink request */
+		pr_info("unlink cleanup rx %lu\n", unlink->unlink_seqnum);
+
+		urb = pickup_urb_and_free_priv(vdev, unlink->unlink_seqnum);
+		if (!urb) {
+			pr_info("the urb (seqnum %lu) was already given back\n",
+				unlink->unlink_seqnum);
+			list_del(&unlink->list);
+			kfree(unlink);
+			continue;
+		}
+
+		urb->status = -ENODEV;
+
+		usb_hcd_unlink_urb_from_ep(hcd, urb);
+
+		list_del(&unlink->list);
+
+		spin_unlock(&vdev->priv_lock);
+		spin_unlock_irqrestore(&vhci->lock, flags);
+
+		usb_hcd_giveback_urb(hcd, urb, urb->status);
+
+		spin_lock_irqsave(&vhci->lock, flags);
+		spin_lock(&vdev->priv_lock);
+
+		kfree(unlink);
+	}
+
+	spin_unlock(&vdev->priv_lock);
+	spin_unlock_irqrestore(&vhci->lock, flags);
+}
+
+/*
+ * The important thing is that only one context begins cleanup.
+ * This is why error handling and cleanup become simple.
+ * We do not want to consider race condition as possible.
+ */
+static void vhci_shutdown_connection(struct usbip_device *ud)
+{
+	struct vhci_device *vdev = container_of(ud, struct vhci_device, ud);
+
+	/* need this? see stub_dev.c */
+	if (ud->tcp_socket) {
+		pr_debug("shutdown tcp_socket %d\n", ud->sockfd);
+		kernel_sock_shutdown(ud->tcp_socket, SHUT_RDWR);
+	}
+
+	/* kill threads related to this sdev */
+	if (vdev->ud.tcp_rx) {
+		kthread_stop_put(vdev->ud.tcp_rx);
+		vdev->ud.tcp_rx = NULL;
+	}
+	if (vdev->ud.tcp_tx) {
+		kthread_stop_put(vdev->ud.tcp_tx);
+		vdev->ud.tcp_tx = NULL;
+	}
+	pr_info("stop threads\n");
+
+	/* active connection is closed */
+	if (vdev->ud.tcp_socket) {
+		sockfd_put(vdev->ud.tcp_socket);
+		vdev->ud.tcp_socket = NULL;
+		vdev->ud.sockfd = -1;
+	}
+	pr_info("release socket\n");
+
+	vhci_device_unlink_cleanup(vdev);
+
+	/*
+	 * rh_port_disconnect() is a trigger of ...
+	 *   usb_disable_device():
+	 *	disable all the endpoints for a USB device.
+	 *   usb_disable_endpoint():
+	 *	disable endpoints. pending urbs are unlinked(dequeued).
+	 *
+	 * NOTE: After calling rh_port_disconnect(), the USB device drivers of a
+	 * detached device should release used urbs in a cleanup function (i.e.
+	 * xxx_disconnect()). Therefore, vhci_hcd does not need to release
+	 * pushed urbs and their private data in this function.
+	 *
+	 * NOTE: vhci_dequeue() must be considered carefully. When shutting down
+	 * a connection, vhci_shutdown_connection() expects vhci_dequeue()
+	 * gives back pushed urbs and frees their private data by request of
+	 * the cleanup function of a USB driver. When unlinking a urb with an
+	 * active connection, vhci_dequeue() does not give back the urb which
+	 * is actually given back by vhci_rx after receiving its return pdu.
+	 *
+	 */
+	rh_port_disconnect(vdev);
+
+	pr_info("disconnect device\n");
+}
+
+static void vhci_device_reset(struct usbip_device *ud)
+{
+	struct vhci_device *vdev = container_of(ud, struct vhci_device, ud);
+	unsigned long flags;
+
+	spin_lock_irqsave(&ud->lock, flags);
+
+	vdev->speed  = 0;
+	vdev->devid  = 0;
+
+	usb_put_dev(vdev->udev);
+	vdev->udev = NULL;
+
+	if (ud->tcp_socket) {
+		sockfd_put(ud->tcp_socket);
+		ud->tcp_socket = NULL;
+		ud->sockfd = -1;
+	}
+	ud->status = VDEV_ST_NULL;
+
+	spin_unlock_irqrestore(&ud->lock, flags);
+}
+
+static void vhci_device_unusable(struct usbip_device *ud)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&ud->lock, flags);
+	ud->status = VDEV_ST_ERROR;
+	spin_unlock_irqrestore(&ud->lock, flags);
+}
+
+static void vhci_device_init(struct vhci_device *vdev)
+{
+	memset(vdev, 0, sizeof(struct vhci_device));
+
+	vdev->ud.side   = USBIP_VHCI;
+	vdev->ud.status = VDEV_ST_NULL;
+	spin_lock_init(&vdev->ud.lock);
+	mutex_init(&vdev->ud.sysfs_lock);
+
+	INIT_LIST_HEAD(&vdev->priv_rx);
+	INIT_LIST_HEAD(&vdev->priv_tx);
+	INIT_LIST_HEAD(&vdev->unlink_tx);
+	INIT_LIST_HEAD(&vdev->unlink_rx);
+	spin_lock_init(&vdev->priv_lock);
+
+	init_waitqueue_head(&vdev->waitq_tx);
+
+	vdev->ud.eh_ops.shutdown = vhci_shutdown_connection;
+	vdev->ud.eh_ops.reset = vhci_device_reset;
+	vdev->ud.eh_ops.unusable = vhci_device_unusable;
+
+	usbip_start_eh(&vdev->ud);
+}
+
+static int hcd_name_to_id(const char *name)
+{
+	char *c;
+	long val;
+	int ret;
+
+	c = strchr(name, '.');
+	if (c == NULL)
+		return 0;
+
+	ret = kstrtol(c+1, 10, &val);
+	if (ret < 0)
+		return ret;
+
+	return val;
+}
+
+static int vhci_setup(struct usb_hcd *hcd)
+{
+	struct vhci *vhci = *((void **)dev_get_platdata(hcd->self.controller));
+	if (usb_hcd_is_primary_hcd(hcd)) {
+		vhci->vhci_hcd_hs = hcd_to_vhci_hcd(hcd);
+		vhci->vhci_hcd_hs->vhci = vhci;
+		/*
+		 * Mark the first roothub as being USB 2.0.
+		 * The USB 3.0 roothub will be registered later by
+		 * vhci_hcd_probe()
+		 */
+		hcd->speed = HCD_USB2;
+		hcd->self.root_hub->speed = USB_SPEED_HIGH;
+	} else {
+		vhci->vhci_hcd_ss = hcd_to_vhci_hcd(hcd);
+		vhci->vhci_hcd_ss->vhci = vhci;
+		hcd->speed = HCD_USB3;
+		hcd->self.root_hub->speed = USB_SPEED_SUPER;
+	}
+
+	/*
+	 * Support SG.
+	 * sg_tablesize is an arbitrary value to alleviate memory pressure
+	 * on the host.
+	 */
+	hcd->self.sg_tablesize = 32;
+	hcd->self.no_sg_constraint = 1;
+
+	return 0;
+}
+
+static int vhci_start(struct usb_hcd *hcd)
+{
+	struct vhci_hcd *vhci_hcd = hcd_to_vhci_hcd(hcd);
+	int id, rhport;
+	int err;
+
+	usbip_dbg_vhci_hc("enter vhci_start\n");
+
+	if (usb_hcd_is_primary_hcd(hcd))
+		spin_lock_init(&vhci_hcd->vhci->lock);
+
+	/* initialize private data of usb_hcd */
+
+	for (rhport = 0; rhport < VHCI_HC_PORTS; rhport++) {
+		struct vhci_device *vdev = &vhci_hcd->vdev[rhport];
+
+		vhci_device_init(vdev);
+		vdev->rhport = rhport;
+	}
+
+	atomic_set(&vhci_hcd->seqnum, 0);
+
+	hcd->power_budget = 0; /* no limit */
+	hcd->uses_new_polling = 1;
+
+#ifdef CONFIG_USB_OTG
+	hcd->self.otg_port = 1;
+#endif
+
+	id = hcd_name_to_id(hcd_name(hcd));
+	if (id < 0) {
+		pr_err("invalid vhci name %s\n", hcd_name(hcd));
+		return -EINVAL;
+	}
+
+	/* vhci_hcd is now ready to be controlled through sysfs */
+	if (id == 0 && usb_hcd_is_primary_hcd(hcd)) {
+		err = vhci_init_attr_group();
+		if (err) {
+			pr_err("init attr group\n");
+			return err;
+		}
+		err = sysfs_create_group(&hcd_dev(hcd)->kobj, &vhci_attr_group);
+		if (err) {
+			pr_err("create sysfs files\n");
+			vhci_finish_attr_group();
+			return err;
+		}
+		pr_info("created sysfs %s\n", hcd_name(hcd));
+	}
+
+	return 0;
+}
+
+static void vhci_stop(struct usb_hcd *hcd)
+{
+	struct vhci_hcd *vhci_hcd = hcd_to_vhci_hcd(hcd);
+	int id, rhport;
+
+	usbip_dbg_vhci_hc("stop VHCI controller\n");
+
+	/* 1. remove the userland interface of vhci_hcd */
+	id = hcd_name_to_id(hcd_name(hcd));
+	if (id == 0 && usb_hcd_is_primary_hcd(hcd)) {
+		sysfs_remove_group(&hcd_dev(hcd)->kobj, &vhci_attr_group);
+		vhci_finish_attr_group();
+	}
+
+	/* 2. shutdown all the ports of vhci_hcd */
+	for (rhport = 0; rhport < VHCI_HC_PORTS; rhport++) {
+		struct vhci_device *vdev = &vhci_hcd->vdev[rhport];
+
+		usbip_event_add(&vdev->ud, VDEV_EVENT_REMOVED);
+		usbip_stop_eh(&vdev->ud);
+	}
+}
+
+static int vhci_get_frame_number(struct usb_hcd *hcd)
+{
+	dev_err_ratelimited(&hcd->self.root_hub->dev, "Not yet implemented\n");
+	return 0;
+}
+
+#ifdef CONFIG_PM
+
+/* FIXME: suspend/resume */
+static int vhci_bus_suspend(struct usb_hcd *hcd)
+{
+	struct vhci *vhci = *((void **)dev_get_platdata(hcd->self.controller));
+	unsigned long flags;
+
+	dev_dbg(&hcd->self.root_hub->dev, "%s\n", __func__);
+
+	spin_lock_irqsave(&vhci->lock, flags);
+	hcd->state = HC_STATE_SUSPENDED;
+	spin_unlock_irqrestore(&vhci->lock, flags);
+
+	return 0;
+}
+
+static int vhci_bus_resume(struct usb_hcd *hcd)
+{
+	struct vhci *vhci = *((void **)dev_get_platdata(hcd->self.controller));
+	int rc = 0;
+	unsigned long flags;
+
+	dev_dbg(&hcd->self.root_hub->dev, "%s\n", __func__);
+
+	spin_lock_irqsave(&vhci->lock, flags);
+	if (!HCD_HW_ACCESSIBLE(hcd))
+		rc = -ESHUTDOWN;
+	else
+		hcd->state = HC_STATE_RUNNING;
+	spin_unlock_irqrestore(&vhci->lock, flags);
+
+	return rc;
+}
+
+#else
+
+#define vhci_bus_suspend      NULL
+#define vhci_bus_resume       NULL
+#endif
+
+/* Change a group of bulk endpoints to support multiple stream IDs */
+static int vhci_alloc_streams(struct usb_hcd *hcd, struct usb_device *udev,
+	struct usb_host_endpoint **eps, unsigned int num_eps,
+	unsigned int num_streams, gfp_t mem_flags)
+{
+	dev_dbg(&hcd->self.root_hub->dev, "vhci_alloc_streams not implemented\n");
+	return 0;
+}
+
+/* Reverts a group of bulk endpoints back to not using stream IDs. */
+static int vhci_free_streams(struct usb_hcd *hcd, struct usb_device *udev,
+	struct usb_host_endpoint **eps, unsigned int num_eps,
+	gfp_t mem_flags)
+{
+	dev_dbg(&hcd->self.root_hub->dev, "vhci_free_streams not implemented\n");
+	return 0;
+}
+
+static const struct hc_driver vhci_hc_driver = {
+	.description	= driver_name,
+	.product_desc	= driver_desc,
+	.hcd_priv_size	= sizeof(struct vhci_hcd),
+
+	.flags		= HCD_USB3 | HCD_SHARED,
+
+	.reset		= vhci_setup,
+	.start		= vhci_start,
+	.stop		= vhci_stop,
+
+	.urb_enqueue	= vhci_urb_enqueue,
+	.urb_dequeue	= vhci_urb_dequeue,
+
+	.get_frame_number = vhci_get_frame_number,
+
+	.hub_status_data = vhci_hub_status,
+	.hub_control    = vhci_hub_control,
+	.bus_suspend	= vhci_bus_suspend,
+	.bus_resume	= vhci_bus_resume,
+
+	.alloc_streams	= vhci_alloc_streams,
+	.free_streams	= vhci_free_streams,
+};
+
+static int vhci_hcd_probe(struct platform_device *pdev)
+{
+	struct vhci             *vhci = *((void **)dev_get_platdata(&pdev->dev));
+	struct usb_hcd		*hcd_hs;
+	struct usb_hcd		*hcd_ss;
+	int			ret;
+
+	usbip_dbg_vhci_hc("name %s id %d\n", pdev->name, pdev->id);
+
+	/*
+	 * Allocate and initialize hcd.
+	 * Our private data is also allocated automatically.
+	 */
+	hcd_hs = usb_create_hcd(&vhci_hc_driver, &pdev->dev, dev_name(&pdev->dev));
+	if (!hcd_hs) {
+		pr_err("create primary hcd failed\n");
+		return -ENOMEM;
+	}
+	hcd_hs->has_tt = 1;
+
+	/*
+	 * Finish generic HCD structure initialization and register.
+	 * Call the driver's reset() and start() routines.
+	 */
+	ret = usb_add_hcd(hcd_hs, 0, 0);
+	if (ret != 0) {
+		pr_err("usb_add_hcd hs failed %d\n", ret);
+		goto put_usb2_hcd;
+	}
+
+	hcd_ss = usb_create_shared_hcd(&vhci_hc_driver, &pdev->dev,
+				       dev_name(&pdev->dev), hcd_hs);
+	if (!hcd_ss) {
+		ret = -ENOMEM;
+		pr_err("create shared hcd failed\n");
+		goto remove_usb2_hcd;
+	}
+
+	ret = usb_add_hcd(hcd_ss, 0, 0);
+	if (ret) {
+		pr_err("usb_add_hcd ss failed %d\n", ret);
+		goto put_usb3_hcd;
+	}
+
+	usbip_dbg_vhci_hc("bye\n");
+	return 0;
+
+put_usb3_hcd:
+	usb_put_hcd(hcd_ss);
+remove_usb2_hcd:
+	usb_remove_hcd(hcd_hs);
+put_usb2_hcd:
+	usb_put_hcd(hcd_hs);
+	vhci->vhci_hcd_hs = NULL;
+	vhci->vhci_hcd_ss = NULL;
+	return ret;
+}
+
+static int vhci_hcd_remove(struct platform_device *pdev)
+{
+	struct vhci *vhci = *((void **)dev_get_platdata(&pdev->dev));
+
+	/*
+	 * Disconnects the root hub,
+	 * then reverses the effects of usb_add_hcd(),
+	 * invoking the HCD's stop() methods.
+	 */
+	usb_remove_hcd(vhci_hcd_to_hcd(vhci->vhci_hcd_ss));
+	usb_put_hcd(vhci_hcd_to_hcd(vhci->vhci_hcd_ss));
+
+	usb_remove_hcd(vhci_hcd_to_hcd(vhci->vhci_hcd_hs));
+	usb_put_hcd(vhci_hcd_to_hcd(vhci->vhci_hcd_hs));
+
+	vhci->vhci_hcd_hs = NULL;
+	vhci->vhci_hcd_ss = NULL;
+
+	return 0;
+}
+
+#ifdef CONFIG_PM
+
+/* what should happen for USB/IP under suspend/resume? */
+static int vhci_hcd_suspend(struct platform_device *pdev, pm_message_t state)
+{
+	struct usb_hcd *hcd;
+	struct vhci *vhci;
+	int rhport;
+	int connected = 0;
+	int ret = 0;
+	unsigned long flags;
+
+	dev_dbg(&pdev->dev, "%s\n", __func__);
+
+	hcd = platform_get_drvdata(pdev);
+	if (!hcd)
+		return 0;
+
+	vhci = *((void **)dev_get_platdata(hcd->self.controller));
+
+	spin_lock_irqsave(&vhci->lock, flags);
+
+	for (rhport = 0; rhport < VHCI_HC_PORTS; rhport++) {
+		if (vhci->vhci_hcd_hs->port_status[rhport] &
+		    USB_PORT_STAT_CONNECTION)
+			connected += 1;
+
+		if (vhci->vhci_hcd_ss->port_status[rhport] &
+		    USB_PORT_STAT_CONNECTION)
+			connected += 1;
+	}
+
+	spin_unlock_irqrestore(&vhci->lock, flags);
+
+	if (connected > 0) {
+		dev_info(&pdev->dev,
+			 "We have %d active connection%s. Do not suspend.\n",
+			 connected, (connected == 1 ? "" : "s"));
+		ret =  -EBUSY;
+	} else {
+		dev_info(&pdev->dev, "suspend vhci_hcd");
+		clear_bit(HCD_FLAG_HW_ACCESSIBLE, &hcd->flags);
+	}
+
+	return ret;
+}
+
+static int vhci_hcd_resume(struct platform_device *pdev)
+{
+	struct usb_hcd *hcd;
+
+	dev_dbg(&pdev->dev, "%s\n", __func__);
+
+	hcd = platform_get_drvdata(pdev);
+	if (!hcd)
+		return 0;
+	set_bit(HCD_FLAG_HW_ACCESSIBLE, &hcd->flags);
+	usb_hcd_poll_rh_status(hcd);
+
+	return 0;
+}
+
+#else
+
+#define vhci_hcd_suspend	NULL
+#define vhci_hcd_resume		NULL
+
+#endif
+
+static struct platform_driver vhci_driver = {
+	.probe	= vhci_hcd_probe,
+	.remove	= vhci_hcd_remove,
+	.suspend = vhci_hcd_suspend,
+	.resume	= vhci_hcd_resume,
+	.driver	= {
+		.name = driver_name,
+	},
+};
+
+static void del_platform_devices(void)
+{
+	struct platform_device *pdev;
+	int i;
+
+	for (i = 0; i < vhci_num_controllers; i++) {
+		pdev = vhcis[i].pdev;
+		if (pdev != NULL)
+			platform_device_unregister(pdev);
+		vhcis[i].pdev = NULL;
+	}
+	sysfs_remove_link(&platform_bus.kobj, driver_name);
+}
+
+static int __init vhci_hcd_init(void)
+{
+	int i, ret;
+
+	if (usb_disabled())
+		return -ENODEV;
+
+	if (vhci_num_controllers < 1)
+		vhci_num_controllers = 1;
+
+	vhcis = kcalloc(vhci_num_controllers, sizeof(struct vhci), GFP_KERNEL);
+	if (vhcis == NULL)
+		return -ENOMEM;
+
+	for (i = 0; i < vhci_num_controllers; i++) {
+		vhcis[i].pdev = platform_device_alloc(driver_name, i);
+		if (!vhcis[i].pdev) {
+			i--;
+			while (i >= 0)
+				platform_device_put(vhcis[i--].pdev);
+			ret = -ENOMEM;
+			goto err_device_alloc;
+		}
+	}
+	for (i = 0; i < vhci_num_controllers; i++) {
+		void *vhci = &vhcis[i];
+		ret = platform_device_add_data(vhcis[i].pdev, &vhci, sizeof(void *));
+		if (ret)
+			goto err_driver_register;
+	}
+
+	ret = platform_driver_register(&vhci_driver);
+	if (ret)
+		goto err_driver_register;
+
+	for (i = 0; i < vhci_num_controllers; i++) {
+		ret = platform_device_add(vhcis[i].pdev);
+		if (ret < 0) {
+			i--;
+			while (i >= 0)
+				platform_device_del(vhcis[i--].pdev);
+			goto err_add_hcd;
+		}
+	}
+
+	return ret;
+
+err_add_hcd:
+	platform_driver_unregister(&vhci_driver);
+err_driver_register:
+	for (i = 0; i < vhci_num_controllers; i++)
+		platform_device_put(vhcis[i].pdev);
+err_device_alloc:
+	kfree(vhcis);
+	return ret;
+}
+
+static void __exit vhci_hcd_exit(void)
+{
+	del_platform_devices();
+	platform_driver_unregister(&vhci_driver);
+	kfree(vhcis);
+}
+
+module_init(vhci_hcd_init);
+module_exit(vhci_hcd_exit);
+
+MODULE_AUTHOR(DRIVER_AUTHOR);
+MODULE_DESCRIPTION(DRIVER_DESC);
+MODULE_LICENSE("GPL");
diff --git a/drivers/usb/usbip/vhci_rx.c b/drivers/usb/usbip/vhci_rx.c
new file mode 100644
index 000000000..00fc98741
--- /dev/null
+++ b/drivers/usb/usbip/vhci_rx.c
@@ -0,0 +1,268 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (C) 2003-2008 Takahiro Hirofuchi
+ */
+
+#include <linux/kthread.h>
+#include <linux/slab.h>
+
+#include "usbip_common.h"
+#include "vhci.h"
+
+/* get URB from transmitted urb queue. caller must hold vdev->priv_lock */
+struct urb *pickup_urb_and_free_priv(struct vhci_device *vdev, __u32 seqnum)
+{
+	struct vhci_priv *priv, *tmp;
+	struct urb *urb = NULL;
+	int status;
+
+	list_for_each_entry_safe(priv, tmp, &vdev->priv_rx, list) {
+		if (priv->seqnum != seqnum)
+			continue;
+
+		urb = priv->urb;
+		status = urb->status;
+
+		usbip_dbg_vhci_rx("find urb seqnum %u\n", seqnum);
+
+		switch (status) {
+		case -ENOENT:
+			/* fall through */
+		case -ECONNRESET:
+			dev_dbg(&urb->dev->dev,
+				 "urb seq# %u was unlinked %ssynchronously\n",
+				 seqnum, status == -ENOENT ? "" : "a");
+			break;
+		case -EINPROGRESS:
+			/* no info output */
+			break;
+		default:
+			dev_dbg(&urb->dev->dev,
+				 "urb seq# %u may be in a error, status %d\n",
+				 seqnum, status);
+		}
+
+		list_del(&priv->list);
+		kfree(priv);
+		urb->hcpriv = NULL;
+
+		break;
+	}
+
+	return urb;
+}
+
+static void vhci_recv_ret_submit(struct vhci_device *vdev,
+				 struct usbip_header *pdu)
+{
+	struct vhci_hcd *vhci_hcd = vdev_to_vhci_hcd(vdev);
+	struct vhci *vhci = vhci_hcd->vhci;
+	struct usbip_device *ud = &vdev->ud;
+	struct urb *urb;
+	unsigned long flags;
+
+	spin_lock_irqsave(&vdev->priv_lock, flags);
+	urb = pickup_urb_and_free_priv(vdev, pdu->base.seqnum);
+	spin_unlock_irqrestore(&vdev->priv_lock, flags);
+
+	if (!urb) {
+		pr_err("cannot find a urb of seqnum %u max seqnum %d\n",
+			pdu->base.seqnum,
+			atomic_read(&vhci_hcd->seqnum));
+		usbip_event_add(ud, VDEV_EVENT_ERROR_TCP);
+		return;
+	}
+
+	/* unpack the pdu to a urb */
+	usbip_pack_pdu(pdu, urb, USBIP_RET_SUBMIT, 0);
+
+	/* recv transfer buffer */
+	if (usbip_recv_xbuff(ud, urb) < 0) {
+		urb->status = -EPROTO;
+		goto error;
+	}
+
+	/* recv iso_packet_descriptor */
+	if (usbip_recv_iso(ud, urb) < 0) {
+		urb->status = -EPROTO;
+		goto error;
+	}
+
+	/* restore the padding in iso packets */
+	usbip_pad_iso(ud, urb);
+
+error:
+	if (usbip_dbg_flag_vhci_rx)
+		usbip_dump_urb(urb);
+
+	if (urb->num_sgs)
+		urb->transfer_flags &= ~URB_DMA_MAP_SG;
+
+	usbip_dbg_vhci_rx("now giveback urb %u\n", pdu->base.seqnum);
+
+	spin_lock_irqsave(&vhci->lock, flags);
+	usb_hcd_unlink_urb_from_ep(vhci_hcd_to_hcd(vhci_hcd), urb);
+	spin_unlock_irqrestore(&vhci->lock, flags);
+
+	usb_hcd_giveback_urb(vhci_hcd_to_hcd(vhci_hcd), urb, urb->status);
+
+	usbip_dbg_vhci_rx("Leave\n");
+}
+
+static struct vhci_unlink *dequeue_pending_unlink(struct vhci_device *vdev,
+						  struct usbip_header *pdu)
+{
+	struct vhci_unlink *unlink, *tmp;
+	unsigned long flags;
+
+	spin_lock_irqsave(&vdev->priv_lock, flags);
+
+	list_for_each_entry_safe(unlink, tmp, &vdev->unlink_rx, list) {
+		pr_info("unlink->seqnum %lu\n", unlink->seqnum);
+		if (unlink->seqnum == pdu->base.seqnum) {
+			usbip_dbg_vhci_rx("found pending unlink, %lu\n",
+					  unlink->seqnum);
+			list_del(&unlink->list);
+
+			spin_unlock_irqrestore(&vdev->priv_lock, flags);
+			return unlink;
+		}
+	}
+
+	spin_unlock_irqrestore(&vdev->priv_lock, flags);
+
+	return NULL;
+}
+
+static void vhci_recv_ret_unlink(struct vhci_device *vdev,
+				 struct usbip_header *pdu)
+{
+	struct vhci_hcd *vhci_hcd = vdev_to_vhci_hcd(vdev);
+	struct vhci *vhci = vhci_hcd->vhci;
+	struct vhci_unlink *unlink;
+	struct urb *urb;
+	unsigned long flags;
+
+	usbip_dump_header(pdu);
+
+	unlink = dequeue_pending_unlink(vdev, pdu);
+	if (!unlink) {
+		pr_info("cannot find the pending unlink %u\n",
+			pdu->base.seqnum);
+		return;
+	}
+
+	spin_lock_irqsave(&vdev->priv_lock, flags);
+	urb = pickup_urb_and_free_priv(vdev, unlink->unlink_seqnum);
+	spin_unlock_irqrestore(&vdev->priv_lock, flags);
+
+	if (!urb) {
+		/*
+		 * I get the result of a unlink request. But, it seems that I
+		 * already received the result of its submit result and gave
+		 * back the URB.
+		 */
+		pr_info("the urb (seqnum %d) was already given back\n",
+			pdu->base.seqnum);
+	} else {
+		usbip_dbg_vhci_rx("now giveback urb %d\n", pdu->base.seqnum);
+
+		/* If unlink is successful, status is -ECONNRESET */
+		urb->status = pdu->u.ret_unlink.status;
+		pr_info("urb->status %d\n", urb->status);
+
+		spin_lock_irqsave(&vhci->lock, flags);
+		usb_hcd_unlink_urb_from_ep(vhci_hcd_to_hcd(vhci_hcd), urb);
+		spin_unlock_irqrestore(&vhci->lock, flags);
+
+		usb_hcd_giveback_urb(vhci_hcd_to_hcd(vhci_hcd), urb, urb->status);
+	}
+
+	kfree(unlink);
+}
+
+static int vhci_priv_tx_empty(struct vhci_device *vdev)
+{
+	int empty = 0;
+	unsigned long flags;
+
+	spin_lock_irqsave(&vdev->priv_lock, flags);
+	empty = list_empty(&vdev->priv_rx);
+	spin_unlock_irqrestore(&vdev->priv_lock, flags);
+
+	return empty;
+}
+
+/* recv a pdu */
+static void vhci_rx_pdu(struct usbip_device *ud)
+{
+	int ret;
+	struct usbip_header pdu;
+	struct vhci_device *vdev = container_of(ud, struct vhci_device, ud);
+
+	usbip_dbg_vhci_rx("Enter\n");
+
+	memset(&pdu, 0, sizeof(pdu));
+
+	/* receive a pdu header */
+	ret = usbip_recv(ud->tcp_socket, &pdu, sizeof(pdu));
+	if (ret < 0) {
+		if (ret == -ECONNRESET)
+			pr_info("connection reset by peer\n");
+		else if (ret == -EAGAIN) {
+			/* ignore if connection was idle */
+			if (vhci_priv_tx_empty(vdev))
+				return;
+			pr_info("connection timed out with pending urbs\n");
+		} else if (ret != -ERESTARTSYS)
+			pr_info("xmit failed %d\n", ret);
+
+		usbip_event_add(ud, VDEV_EVENT_ERROR_TCP);
+		return;
+	}
+	if (ret == 0) {
+		pr_info("connection closed");
+		usbip_event_add(ud, VDEV_EVENT_DOWN);
+		return;
+	}
+	if (ret != sizeof(pdu)) {
+		pr_err("received pdu size is %d, should be %d\n", ret,
+		       (unsigned int)sizeof(pdu));
+		usbip_event_add(ud, VDEV_EVENT_ERROR_TCP);
+		return;
+	}
+
+	usbip_header_correct_endian(&pdu, 0);
+
+	if (usbip_dbg_flag_vhci_rx)
+		usbip_dump_header(&pdu);
+
+	switch (pdu.base.command) {
+	case USBIP_RET_SUBMIT:
+		vhci_recv_ret_submit(vdev, &pdu);
+		break;
+	case USBIP_RET_UNLINK:
+		vhci_recv_ret_unlink(vdev, &pdu);
+		break;
+	default:
+		/* NOT REACHED */
+		pr_err("unknown pdu %u\n", pdu.base.command);
+		usbip_dump_header(&pdu);
+		usbip_event_add(ud, VDEV_EVENT_ERROR_TCP);
+		break;
+	}
+}
+
+int vhci_rx_loop(void *data)
+{
+	struct usbip_device *ud = data;
+
+	while (!kthread_should_stop()) {
+		if (usbip_event_happened(ud))
+			break;
+
+		vhci_rx_pdu(ud);
+	}
+
+	return 0;
+}
diff --git a/drivers/usb/usbip/vhci_sysfs.c b/drivers/usb/usbip/vhci_sysfs.c
new file mode 100644
index 000000000..ebc7be1d9
--- /dev/null
+++ b/drivers/usb/usbip/vhci_sysfs.c
@@ -0,0 +1,526 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (C) 2003-2008 Takahiro Hirofuchi
+ * Copyright (C) 2015-2016 Nobuo Iwata
+ */
+
+#include <linux/kthread.h>
+#include <linux/file.h>
+#include <linux/net.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+
+/* Hardening for Spectre-v1 */
+#include <linux/nospec.h>
+
+#include "usbip_common.h"
+#include "vhci.h"
+
+/* TODO: refine locking ?*/
+
+/*
+ * output example:
+ * hub port sta spd dev       sockfd local_busid
+ * hs  0000 004 000 00000000  000003 1-2.3
+ * ................................................
+ * ss  0008 004 000 00000000  000004 2-3.4
+ * ................................................
+ *
+ * Output includes socket fd instead of socket pointer address to avoid
+ * leaking kernel memory address in:
+ *	/sys/devices/platform/vhci_hcd.0/status and in debug output.
+ * The socket pointer address is not used at the moment and it was made
+ * visible as a convenient way to find IP address from socket pointer
+ * address by looking up /proc/net/{tcp,tcp6}. As this opens a security
+ * hole, the change is made to use sockfd instead.
+ *
+ */
+static void port_show_vhci(char **out, int hub, int port, struct vhci_device *vdev)
+{
+	if (hub == HUB_SPEED_HIGH)
+		*out += sprintf(*out, "hs  %04u %03u ",
+				      port, vdev->ud.status);
+	else /* hub == HUB_SPEED_SUPER */
+		*out += sprintf(*out, "ss  %04u %03u ",
+				      port, vdev->ud.status);
+
+	if (vdev->ud.status == VDEV_ST_USED) {
+		*out += sprintf(*out, "%03u %08x ",
+				      vdev->speed, vdev->devid);
+		*out += sprintf(*out, "%06u %s",
+				      vdev->ud.sockfd,
+				      dev_name(&vdev->udev->dev));
+
+	} else {
+		*out += sprintf(*out, "000 00000000 ");
+		*out += sprintf(*out, "000000 0-0");
+	}
+
+	*out += sprintf(*out, "\n");
+}
+
+/* Sysfs entry to show port status */
+static ssize_t status_show_vhci(int pdev_nr, char *out)
+{
+	struct platform_device *pdev = vhcis[pdev_nr].pdev;
+	struct vhci *vhci;
+	struct usb_hcd *hcd;
+	struct vhci_hcd *vhci_hcd;
+	char *s = out;
+	int i;
+	unsigned long flags;
+
+	if (!pdev || !out) {
+		usbip_dbg_vhci_sysfs("show status error\n");
+		return 0;
+	}
+
+	hcd = platform_get_drvdata(pdev);
+	vhci_hcd = hcd_to_vhci_hcd(hcd);
+	vhci = vhci_hcd->vhci;
+
+	spin_lock_irqsave(&vhci->lock, flags);
+
+	for (i = 0; i < VHCI_HC_PORTS; i++) {
+		struct vhci_device *vdev = &vhci->vhci_hcd_hs->vdev[i];
+
+		spin_lock(&vdev->ud.lock);
+		port_show_vhci(&out, HUB_SPEED_HIGH,
+			       pdev_nr * VHCI_PORTS + i, vdev);
+		spin_unlock(&vdev->ud.lock);
+	}
+
+	for (i = 0; i < VHCI_HC_PORTS; i++) {
+		struct vhci_device *vdev = &vhci->vhci_hcd_ss->vdev[i];
+
+		spin_lock(&vdev->ud.lock);
+		port_show_vhci(&out, HUB_SPEED_SUPER,
+			       pdev_nr * VHCI_PORTS + VHCI_HC_PORTS + i, vdev);
+		spin_unlock(&vdev->ud.lock);
+	}
+
+	spin_unlock_irqrestore(&vhci->lock, flags);
+
+	return out - s;
+}
+
+static ssize_t status_show_not_ready(int pdev_nr, char *out)
+{
+	char *s = out;
+	int i = 0;
+
+	for (i = 0; i < VHCI_HC_PORTS; i++) {
+		out += sprintf(out, "hs  %04u %03u ",
+				    (pdev_nr * VHCI_PORTS) + i,
+				    VDEV_ST_NOTASSIGNED);
+		out += sprintf(out, "000 00000000 0000000000000000 0-0");
+		out += sprintf(out, "\n");
+	}
+
+	for (i = 0; i < VHCI_HC_PORTS; i++) {
+		out += sprintf(out, "ss  %04u %03u ",
+				    (pdev_nr * VHCI_PORTS) + VHCI_HC_PORTS + i,
+				    VDEV_ST_NOTASSIGNED);
+		out += sprintf(out, "000 00000000 0000000000000000 0-0");
+		out += sprintf(out, "\n");
+	}
+	return out - s;
+}
+
+static int status_name_to_id(const char *name)
+{
+	char *c;
+	long val;
+	int ret;
+
+	c = strchr(name, '.');
+	if (c == NULL)
+		return 0;
+
+	ret = kstrtol(c+1, 10, &val);
+	if (ret < 0)
+		return ret;
+
+	return val;
+}
+
+static ssize_t status_show(struct device *dev,
+			   struct device_attribute *attr, char *out)
+{
+	char *s = out;
+	int pdev_nr;
+
+	out += sprintf(out,
+		       "hub port sta spd dev      sockfd local_busid\n");
+
+	pdev_nr = status_name_to_id(attr->attr.name);
+	if (pdev_nr < 0)
+		out += status_show_not_ready(pdev_nr, out);
+	else
+		out += status_show_vhci(pdev_nr, out);
+
+	return out - s;
+}
+
+static ssize_t nports_show(struct device *dev, struct device_attribute *attr,
+			   char *out)
+{
+	char *s = out;
+
+	/*
+	 * Half the ports are for SPEED_HIGH and half for SPEED_SUPER,
+	 * thus the * 2.
+	 */
+	out += sprintf(out, "%d\n", VHCI_PORTS * vhci_num_controllers);
+	return out - s;
+}
+static DEVICE_ATTR_RO(nports);
+
+/* Sysfs entry to shutdown a virtual connection */
+static int vhci_port_disconnect(struct vhci_hcd *vhci_hcd, __u32 rhport)
+{
+	struct vhci_device *vdev = &vhci_hcd->vdev[rhport];
+	struct vhci *vhci = vhci_hcd->vhci;
+	unsigned long flags;
+
+	usbip_dbg_vhci_sysfs("enter\n");
+
+	mutex_lock(&vdev->ud.sysfs_lock);
+
+	/* lock */
+	spin_lock_irqsave(&vhci->lock, flags);
+	spin_lock(&vdev->ud.lock);
+
+	if (vdev->ud.status == VDEV_ST_NULL) {
+		pr_err("not connected %d\n", vdev->ud.status);
+
+		/* unlock */
+		spin_unlock(&vdev->ud.lock);
+		spin_unlock_irqrestore(&vhci->lock, flags);
+		mutex_unlock(&vdev->ud.sysfs_lock);
+
+		return -EINVAL;
+	}
+
+	/* unlock */
+	spin_unlock(&vdev->ud.lock);
+	spin_unlock_irqrestore(&vhci->lock, flags);
+
+	usbip_event_add(&vdev->ud, VDEV_EVENT_DOWN);
+
+	mutex_unlock(&vdev->ud.sysfs_lock);
+
+	return 0;
+}
+
+static int valid_port(__u32 *pdev_nr, __u32 *rhport)
+{
+	if (*pdev_nr >= vhci_num_controllers) {
+		pr_err("pdev %u\n", *pdev_nr);
+		return 0;
+	}
+	*pdev_nr = array_index_nospec(*pdev_nr, vhci_num_controllers);
+
+	if (*rhport >= VHCI_HC_PORTS) {
+		pr_err("rhport %u\n", *rhport);
+		return 0;
+	}
+	*rhport = array_index_nospec(*rhport, VHCI_HC_PORTS);
+
+	return 1;
+}
+
+static ssize_t detach_store(struct device *dev, struct device_attribute *attr,
+			    const char *buf, size_t count)
+{
+	__u32 port = 0, pdev_nr = 0, rhport = 0;
+	struct usb_hcd *hcd;
+	struct vhci_hcd *vhci_hcd;
+	int ret;
+
+	if (kstrtoint(buf, 10, &port) < 0)
+		return -EINVAL;
+
+	pdev_nr = port_to_pdev_nr(port);
+	rhport = port_to_rhport(port);
+
+	if (!valid_port(&pdev_nr, &rhport))
+		return -EINVAL;
+
+	hcd = platform_get_drvdata(vhcis[pdev_nr].pdev);
+	if (hcd == NULL) {
+		dev_err(dev, "port is not ready %u\n", port);
+		return -EAGAIN;
+	}
+
+	usbip_dbg_vhci_sysfs("rhport %d\n", rhport);
+
+	if ((port / VHCI_HC_PORTS) % 2)
+		vhci_hcd = hcd_to_vhci_hcd(hcd)->vhci->vhci_hcd_ss;
+	else
+		vhci_hcd = hcd_to_vhci_hcd(hcd)->vhci->vhci_hcd_hs;
+
+	ret = vhci_port_disconnect(vhci_hcd, rhport);
+	if (ret < 0)
+		return -EINVAL;
+
+	usbip_dbg_vhci_sysfs("Leave\n");
+
+	return count;
+}
+static DEVICE_ATTR_WO(detach);
+
+static int valid_args(__u32 *pdev_nr, __u32 *rhport,
+		      enum usb_device_speed speed)
+{
+	if (!valid_port(pdev_nr, rhport)) {
+		return 0;
+	}
+
+	switch (speed) {
+	case USB_SPEED_LOW:
+	case USB_SPEED_FULL:
+	case USB_SPEED_HIGH:
+	case USB_SPEED_WIRELESS:
+	case USB_SPEED_SUPER:
+		break;
+	default:
+		pr_err("Failed attach request for unsupported USB speed: %s\n",
+			usb_speed_string(speed));
+		return 0;
+	}
+
+	return 1;
+}
+
+/* Sysfs entry to establish a virtual connection */
+/*
+ * To start a new USB/IP attachment, a userland program needs to setup a TCP
+ * connection and then write its socket descriptor with remote device
+ * information into this sysfs file.
+ *
+ * A remote device is virtually attached to the root-hub port of @rhport with
+ * @speed. @devid is embedded into a request to specify the remote device in a
+ * server host.
+ *
+ * write() returns 0 on success, else negative errno.
+ */
+static ssize_t attach_store(struct device *dev, struct device_attribute *attr,
+			    const char *buf, size_t count)
+{
+	struct socket *socket;
+	int sockfd = 0;
+	__u32 port = 0, pdev_nr = 0, rhport = 0, devid = 0, speed = 0;
+	struct usb_hcd *hcd;
+	struct vhci_hcd *vhci_hcd;
+	struct vhci_device *vdev;
+	struct vhci *vhci;
+	int err;
+	unsigned long flags;
+	struct task_struct *tcp_rx = NULL;
+	struct task_struct *tcp_tx = NULL;
+
+	/*
+	 * @rhport: port number of vhci_hcd
+	 * @sockfd: socket descriptor of an established TCP connection
+	 * @devid: unique device identifier in a remote host
+	 * @speed: usb device speed in a remote host
+	 */
+	if (sscanf(buf, "%u %u %u %u", &port, &sockfd, &devid, &speed) != 4)
+		return -EINVAL;
+	pdev_nr = port_to_pdev_nr(port);
+	rhport = port_to_rhport(port);
+
+	usbip_dbg_vhci_sysfs("port(%u) pdev(%d) rhport(%u)\n",
+			     port, pdev_nr, rhport);
+	usbip_dbg_vhci_sysfs("sockfd(%u) devid(%u) speed(%u)\n",
+			     sockfd, devid, speed);
+
+	/* check received parameters */
+	if (!valid_args(&pdev_nr, &rhport, speed))
+		return -EINVAL;
+
+	hcd = platform_get_drvdata(vhcis[pdev_nr].pdev);
+	if (hcd == NULL) {
+		dev_err(dev, "port %d is not ready\n", port);
+		return -EAGAIN;
+	}
+
+	vhci_hcd = hcd_to_vhci_hcd(hcd);
+	vhci = vhci_hcd->vhci;
+
+	if (speed == USB_SPEED_SUPER)
+		vdev = &vhci->vhci_hcd_ss->vdev[rhport];
+	else
+		vdev = &vhci->vhci_hcd_hs->vdev[rhport];
+
+	mutex_lock(&vdev->ud.sysfs_lock);
+
+	/* Extract socket from fd. */
+	socket = sockfd_lookup(sockfd, &err);
+	if (!socket) {
+		dev_err(dev, "failed to lookup sock");
+		err = -EINVAL;
+		goto unlock_mutex;
+	}
+	if (socket->type != SOCK_STREAM) {
+		dev_err(dev, "Expecting SOCK_STREAM - found %d",
+			socket->type);
+		sockfd_put(socket);
+		err = -EINVAL;
+		goto unlock_mutex;
+	}
+
+	/* create threads before locking */
+	tcp_rx = kthread_create(vhci_rx_loop, &vdev->ud, "vhci_rx");
+	if (IS_ERR(tcp_rx)) {
+		sockfd_put(socket);
+		err = -EINVAL;
+		goto unlock_mutex;
+	}
+	tcp_tx = kthread_create(vhci_tx_loop, &vdev->ud, "vhci_tx");
+	if (IS_ERR(tcp_tx)) {
+		kthread_stop(tcp_rx);
+		sockfd_put(socket);
+		err = -EINVAL;
+		goto unlock_mutex;
+	}
+
+	/* get task structs now */
+	get_task_struct(tcp_rx);
+	get_task_struct(tcp_tx);
+
+	/* now begin lock until setting vdev status set */
+	spin_lock_irqsave(&vhci->lock, flags);
+	spin_lock(&vdev->ud.lock);
+
+	if (vdev->ud.status != VDEV_ST_NULL) {
+		/* end of the lock */
+		spin_unlock(&vdev->ud.lock);
+		spin_unlock_irqrestore(&vhci->lock, flags);
+
+		sockfd_put(socket);
+		kthread_stop_put(tcp_rx);
+		kthread_stop_put(tcp_tx);
+
+		dev_err(dev, "port %d already used\n", rhport);
+		/*
+		 * Will be retried from userspace
+		 * if there's another free port.
+		 */
+		err = -EBUSY;
+		goto unlock_mutex;
+	}
+
+	dev_info(dev, "pdev(%u) rhport(%u) sockfd(%d)\n",
+		 pdev_nr, rhport, sockfd);
+	dev_info(dev, "devid(%u) speed(%u) speed_str(%s)\n",
+		 devid, speed, usb_speed_string(speed));
+
+	vdev->devid         = devid;
+	vdev->speed         = speed;
+	vdev->ud.sockfd     = sockfd;
+	vdev->ud.tcp_socket = socket;
+	vdev->ud.tcp_rx     = tcp_rx;
+	vdev->ud.tcp_tx     = tcp_tx;
+	vdev->ud.status     = VDEV_ST_NOTASSIGNED;
+
+	spin_unlock(&vdev->ud.lock);
+	spin_unlock_irqrestore(&vhci->lock, flags);
+	/* end the lock */
+
+	wake_up_process(vdev->ud.tcp_rx);
+	wake_up_process(vdev->ud.tcp_tx);
+
+	rh_port_connect(vdev, speed);
+
+	dev_info(dev, "Device attached\n");
+
+	mutex_unlock(&vdev->ud.sysfs_lock);
+
+	return count;
+
+unlock_mutex:
+	mutex_unlock(&vdev->ud.sysfs_lock);
+	return err;
+}
+static DEVICE_ATTR_WO(attach);
+
+#define MAX_STATUS_NAME 16
+
+struct status_attr {
+	struct device_attribute attr;
+	char name[MAX_STATUS_NAME+1];
+};
+
+static struct status_attr *status_attrs;
+
+static void set_status_attr(int id)
+{
+	struct status_attr *status;
+
+	status = status_attrs + id;
+	if (id == 0)
+		strcpy(status->name, "status");
+	else
+		snprintf(status->name, MAX_STATUS_NAME+1, "status.%d", id);
+	status->attr.attr.name = status->name;
+	status->attr.attr.mode = S_IRUGO;
+	status->attr.show = status_show;
+	sysfs_attr_init(&status->attr.attr);
+}
+
+static int init_status_attrs(void)
+{
+	int id;
+
+	status_attrs = kcalloc(vhci_num_controllers, sizeof(struct status_attr),
+			       GFP_KERNEL);
+	if (status_attrs == NULL)
+		return -ENOMEM;
+
+	for (id = 0; id < vhci_num_controllers; id++)
+		set_status_attr(id);
+
+	return 0;
+}
+
+static void finish_status_attrs(void)
+{
+	kfree(status_attrs);
+}
+
+struct attribute_group vhci_attr_group = {
+	.attrs = NULL,
+};
+
+int vhci_init_attr_group(void)
+{
+	struct attribute **attrs;
+	int ret, i;
+
+	attrs = kcalloc((vhci_num_controllers + 5), sizeof(struct attribute *),
+			GFP_KERNEL);
+	if (attrs == NULL)
+		return -ENOMEM;
+
+	ret = init_status_attrs();
+	if (ret) {
+		kfree(attrs);
+		return ret;
+	}
+	*attrs = &dev_attr_nports.attr;
+	*(attrs + 1) = &dev_attr_detach.attr;
+	*(attrs + 2) = &dev_attr_attach.attr;
+	*(attrs + 3) = &dev_attr_usbip_debug.attr;
+	for (i = 0; i < vhci_num_controllers; i++)
+		*(attrs + i + 4) = &((status_attrs + i)->attr.attr);
+	vhci_attr_group.attrs = attrs;
+	return 0;
+}
+
+void vhci_finish_attr_group(void)
+{
+	finish_status_attrs();
+	kfree(vhci_attr_group.attrs);
+}
diff --git a/drivers/usb/usbip/vhci_tx.c b/drivers/usb/usbip/vhci_tx.c
new file mode 100644
index 000000000..acac49402
--- /dev/null
+++ b/drivers/usb/usbip/vhci_tx.c
@@ -0,0 +1,258 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (C) 2003-2008 Takahiro Hirofuchi
+ */
+
+#include <linux/kthread.h>
+#include <linux/slab.h>
+#include <linux/scatterlist.h>
+
+#include "usbip_common.h"
+#include "vhci.h"
+
+static void setup_cmd_submit_pdu(struct usbip_header *pdup,  struct urb *urb)
+{
+	struct vhci_priv *priv = ((struct vhci_priv *)urb->hcpriv);
+	struct vhci_device *vdev = priv->vdev;
+
+	usbip_dbg_vhci_tx("URB, local devnum %u, remote devid %u\n",
+			  usb_pipedevice(urb->pipe), vdev->devid);
+
+	pdup->base.command   = USBIP_CMD_SUBMIT;
+	pdup->base.seqnum    = priv->seqnum;
+	pdup->base.devid     = vdev->devid;
+	pdup->base.direction = usb_pipein(urb->pipe) ?
+		USBIP_DIR_IN : USBIP_DIR_OUT;
+	pdup->base.ep	     = usb_pipeendpoint(urb->pipe);
+
+	usbip_pack_pdu(pdup, urb, USBIP_CMD_SUBMIT, 1);
+
+	if (urb->setup_packet)
+		memcpy(pdup->u.cmd_submit.setup, urb->setup_packet, 8);
+}
+
+static struct vhci_priv *dequeue_from_priv_tx(struct vhci_device *vdev)
+{
+	struct vhci_priv *priv, *tmp;
+	unsigned long flags;
+
+	spin_lock_irqsave(&vdev->priv_lock, flags);
+
+	list_for_each_entry_safe(priv, tmp, &vdev->priv_tx, list) {
+		list_move_tail(&priv->list, &vdev->priv_rx);
+		spin_unlock_irqrestore(&vdev->priv_lock, flags);
+		return priv;
+	}
+
+	spin_unlock_irqrestore(&vdev->priv_lock, flags);
+
+	return NULL;
+}
+
+static int vhci_send_cmd_submit(struct vhci_device *vdev)
+{
+	struct usbip_iso_packet_descriptor *iso_buffer = NULL;
+	struct vhci_priv *priv = NULL;
+	struct scatterlist *sg;
+
+	struct msghdr msg;
+	struct kvec *iov;
+	size_t txsize;
+
+	size_t total_size = 0;
+	int iovnum;
+	int err = -ENOMEM;
+	int i;
+
+	while ((priv = dequeue_from_priv_tx(vdev)) != NULL) {
+		int ret;
+		struct urb *urb = priv->urb;
+		struct usbip_header pdu_header;
+
+		txsize = 0;
+		memset(&pdu_header, 0, sizeof(pdu_header));
+		memset(&msg, 0, sizeof(msg));
+		memset(&iov, 0, sizeof(iov));
+
+		usbip_dbg_vhci_tx("setup txdata urb seqnum %lu\n",
+				  priv->seqnum);
+
+		if (urb->num_sgs && usb_pipeout(urb->pipe))
+			iovnum = 2 + urb->num_sgs;
+		else
+			iovnum = 3;
+
+		iov = kcalloc(iovnum, sizeof(*iov), GFP_KERNEL);
+		if (!iov) {
+			usbip_event_add(&vdev->ud, SDEV_EVENT_ERROR_MALLOC);
+			return -ENOMEM;
+		}
+
+		if (urb->num_sgs)
+			urb->transfer_flags |= URB_DMA_MAP_SG;
+
+		/* 1. setup usbip_header */
+		setup_cmd_submit_pdu(&pdu_header, urb);
+		usbip_header_correct_endian(&pdu_header, 1);
+		iovnum = 0;
+
+		iov[iovnum].iov_base = &pdu_header;
+		iov[iovnum].iov_len  = sizeof(pdu_header);
+		txsize += sizeof(pdu_header);
+		iovnum++;
+
+		/* 2. setup transfer buffer */
+		if (!usb_pipein(urb->pipe) && urb->transfer_buffer_length > 0) {
+			if (urb->num_sgs &&
+				      !usb_endpoint_xfer_isoc(&urb->ep->desc)) {
+				for_each_sg(urb->sg, sg, urb->num_sgs, i) {
+					iov[iovnum].iov_base = sg_virt(sg);
+					iov[iovnum].iov_len = sg->length;
+					iovnum++;
+				}
+			} else {
+				iov[iovnum].iov_base = urb->transfer_buffer;
+				iov[iovnum].iov_len  =
+						urb->transfer_buffer_length;
+				iovnum++;
+			}
+			txsize += urb->transfer_buffer_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(&vdev->ud,
+						SDEV_EVENT_ERROR_MALLOC);
+				goto err_iso_buffer;
+			}
+
+			iov[iovnum].iov_base = iso_buffer;
+			iov[iovnum].iov_len  = len;
+			iovnum++;
+			txsize += len;
+		}
+
+		ret = kernel_sendmsg(vdev->ud.tcp_socket, &msg, iov, iovnum,
+				     txsize);
+		if (ret != txsize) {
+			pr_err("sendmsg failed!, ret=%d for %zd\n", ret,
+			       txsize);
+			usbip_event_add(&vdev->ud, VDEV_EVENT_ERROR_TCP);
+			err = -EPIPE;
+			goto err_tx;
+		}
+
+		kfree(iov);
+		/* This is only for isochronous case */
+		kfree(iso_buffer);
+		iso_buffer = NULL;
+
+		usbip_dbg_vhci_tx("send txdata\n");
+
+		total_size += txsize;
+	}
+
+	return total_size;
+
+err_tx:
+	kfree(iso_buffer);
+err_iso_buffer:
+	kfree(iov);
+
+	return err;
+}
+
+static struct vhci_unlink *dequeue_from_unlink_tx(struct vhci_device *vdev)
+{
+	struct vhci_unlink *unlink, *tmp;
+	unsigned long flags;
+
+	spin_lock_irqsave(&vdev->priv_lock, flags);
+
+	list_for_each_entry_safe(unlink, tmp, &vdev->unlink_tx, list) {
+		list_move_tail(&unlink->list, &vdev->unlink_rx);
+		spin_unlock_irqrestore(&vdev->priv_lock, flags);
+		return unlink;
+	}
+
+	spin_unlock_irqrestore(&vdev->priv_lock, flags);
+
+	return NULL;
+}
+
+static int vhci_send_cmd_unlink(struct vhci_device *vdev)
+{
+	struct vhci_unlink *unlink = NULL;
+
+	struct msghdr msg;
+	struct kvec iov[3];
+	size_t txsize;
+
+	size_t total_size = 0;
+
+	while ((unlink = dequeue_from_unlink_tx(vdev)) != 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));
+
+		usbip_dbg_vhci_tx("setup cmd unlink, %lu\n", unlink->seqnum);
+
+		/* 1. setup usbip_header */
+		pdu_header.base.command = USBIP_CMD_UNLINK;
+		pdu_header.base.seqnum  = unlink->seqnum;
+		pdu_header.base.devid	= vdev->devid;
+		pdu_header.base.ep	= 0;
+		pdu_header.u.cmd_unlink.seqnum = unlink->unlink_seqnum;
+
+		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(vdev->ud.tcp_socket, &msg, iov, 1, txsize);
+		if (ret != txsize) {
+			pr_err("sendmsg failed!, ret=%d for %zd\n", ret,
+			       txsize);
+			usbip_event_add(&vdev->ud, VDEV_EVENT_ERROR_TCP);
+			return -1;
+		}
+
+		usbip_dbg_vhci_tx("send txdata\n");
+
+		total_size += txsize;
+	}
+
+	return total_size;
+}
+
+int vhci_tx_loop(void *data)
+{
+	struct usbip_device *ud = data;
+	struct vhci_device *vdev = container_of(ud, struct vhci_device, ud);
+
+	while (!kthread_should_stop()) {
+		if (vhci_send_cmd_submit(vdev) < 0)
+			break;
+
+		if (vhci_send_cmd_unlink(vdev) < 0)
+			break;
+
+		wait_event_interruptible(vdev->waitq_tx,
+					 (!list_empty(&vdev->priv_tx) ||
+					  !list_empty(&vdev->unlink_tx) ||
+					  kthread_should_stop()));
+
+		usbip_dbg_vhci_tx("pending urbs ?, now wake up\n");
+	}
+
+	return 0;
+}
diff --git a/drivers/usb/usbip/vudc.h b/drivers/usb/usbip/vudc.h
new file mode 100644
index 000000000..cf968192e
--- /dev/null
+++ b/drivers/usb/usbip/vudc.h
@@ -0,0 +1,178 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (C) 2015 Karol Kosik <karo9@interia.eu>
+ * Copyright (C) 2015-2016 Samsung Electronics
+ *               Igor Kotrasinski <i.kotrasinsk@samsung.com>
+ *               Krzysztof Opasiak <k.opasiak@samsung.com>
+ */
+
+#ifndef __USBIP_VUDC_H
+#define __USBIP_VUDC_H
+
+#include <linux/platform_device.h>
+#include <linux/usb.h>
+#include <linux/usb/gadget.h>
+#include <linux/usb/ch9.h>
+#include <linux/list.h>
+#include <linux/timer.h>
+#include <linux/time.h>
+#include <linux/sysfs.h>
+
+#include "usbip_common.h"
+
+#define GADGET_NAME "usbip-vudc"
+
+struct vep {
+	struct usb_ep ep;
+	unsigned type:2; /* type, as USB_ENDPOINT_XFER_* */
+	char name[8];	/* space for ep name */
+
+	const struct usb_endpoint_descriptor *desc;
+	struct usb_gadget *gadget;
+	struct list_head req_queue; /* Request queue */
+	unsigned halted:1;
+	unsigned wedged:1;
+	unsigned already_seen:1;
+	unsigned setup_stage:1;
+};
+
+struct vrequest {
+	struct usb_request req;
+	struct vudc *udc;
+	struct list_head req_entry; /* Request queue */
+};
+
+struct urbp {
+	struct urb *urb;
+	struct vep *ep;
+	struct list_head urb_entry; /* urb queue */
+	unsigned long seqnum;
+	unsigned type:2; /* for tx, since ep type can change after */
+	unsigned new:1;
+};
+
+struct v_unlink {
+	unsigned long seqnum;
+	__u32 status;
+};
+
+enum tx_type {
+	TX_UNLINK,
+	TX_SUBMIT,
+};
+
+struct tx_item {
+	struct list_head tx_entry;
+	enum tx_type type;
+	union {
+		struct urbp *s;
+		struct v_unlink *u;
+	};
+};
+
+enum tr_state {
+	VUDC_TR_RUNNING,
+	VUDC_TR_IDLE,
+	VUDC_TR_STOPPED,
+};
+
+struct transfer_timer {
+	struct timer_list timer;
+	enum tr_state state;
+	unsigned long frame_start;
+	int frame_limit;
+};
+
+struct vudc {
+	struct usb_gadget gadget;
+	struct usb_gadget_driver *driver;
+	struct platform_device *pdev;
+
+	struct usb_device_descriptor dev_desc;
+
+	struct usbip_device ud;
+	struct transfer_timer tr_timer;
+	struct timespec64 start_time;
+
+	struct list_head urb_queue;
+
+	spinlock_t lock_tx;
+	struct list_head tx_queue;
+	wait_queue_head_t tx_waitq;
+
+	spinlock_t lock;
+	struct vep *ep;
+	int address;
+	u16 devstatus;
+
+	unsigned pullup:1;
+	unsigned connected:1;
+	unsigned desc_cached:1;
+};
+
+struct vudc_device {
+	struct platform_device *pdev;
+	struct list_head dev_entry;
+};
+
+extern const struct attribute_group vudc_attr_group;
+
+/* visible everywhere */
+
+static inline struct vep *to_vep(struct usb_ep *_ep)
+{
+	return container_of(_ep, struct vep, ep);
+}
+
+static inline struct vrequest *to_vrequest(
+	struct usb_request *_req)
+{
+	return container_of(_req, struct vrequest, req);
+}
+
+static inline struct vudc *usb_gadget_to_vudc(
+	struct usb_gadget *_gadget)
+{
+	return container_of(_gadget, struct vudc, gadget);
+}
+
+static inline struct vudc *ep_to_vudc(struct vep *ep)
+{
+	return container_of(ep->gadget, struct vudc, gadget);
+}
+
+/* vudc_sysfs.c */
+
+int get_gadget_descs(struct vudc *udc);
+
+/* vudc_tx.c */
+
+int v_tx_loop(void *data);
+void v_enqueue_ret_unlink(struct vudc *udc, __u32 seqnum, __u32 status);
+void v_enqueue_ret_submit(struct vudc *udc, struct urbp *urb_p);
+
+/* vudc_rx.c */
+
+int v_rx_loop(void *data);
+
+/* vudc_transfer.c */
+
+void v_init_timer(struct vudc *udc);
+void v_start_timer(struct vudc *udc);
+void v_kick_timer(struct vudc *udc, unsigned long time);
+void v_stop_timer(struct vudc *udc);
+
+/* vudc_dev.c */
+
+struct urbp *alloc_urbp(void);
+void free_urbp_and_urb(struct urbp *urb_p);
+
+struct vep *vudc_find_endpoint(struct vudc *udc, u8 address);
+
+struct vudc_device *alloc_vudc_device(int devid);
+void put_vudc_device(struct vudc_device *udc_dev);
+
+int vudc_probe(struct platform_device *pdev);
+int vudc_remove(struct platform_device *pdev);
+
+#endif /* __USBIP_VUDC_H */
diff --git a/drivers/usb/usbip/vudc_dev.c b/drivers/usb/usbip/vudc_dev.c
new file mode 100644
index 000000000..74568325d
--- /dev/null
+++ b/drivers/usb/usbip/vudc_dev.c
@@ -0,0 +1,648 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (C) 2015 Karol Kosik <karo9@interia.eu>
+ * Copyright (C) 2015-2016 Samsung Electronics
+ *               Igor Kotrasinski <i.kotrasinsk@samsung.com>
+ *               Krzysztof Opasiak <k.opasiak@samsung.com>
+ */
+
+#include <linux/device.h>
+#include <linux/kernel.h>
+#include <linux/list.h>
+#include <linux/platform_device.h>
+#include <linux/usb.h>
+#include <linux/usb/gadget.h>
+#include <linux/usb/hcd.h>
+#include <linux/kthread.h>
+#include <linux/file.h>
+#include <linux/byteorder/generic.h>
+
+#include "usbip_common.h"
+#include "vudc.h"
+
+#define VIRTUAL_ENDPOINTS (1 /* ep0 */ + 15 /* in eps */ + 15 /* out eps */)
+
+/* urb-related structures alloc / free */
+
+
+static void free_urb(struct urb *urb)
+{
+	if (!urb)
+		return;
+
+	kfree(urb->setup_packet);
+	urb->setup_packet = NULL;
+
+	kfree(urb->transfer_buffer);
+	urb->transfer_buffer = NULL;
+
+	usb_free_urb(urb);
+}
+
+struct urbp *alloc_urbp(void)
+{
+	struct urbp *urb_p;
+
+	urb_p = kzalloc(sizeof(*urb_p), GFP_KERNEL);
+	if (!urb_p)
+		return urb_p;
+
+	urb_p->urb = NULL;
+	urb_p->ep = NULL;
+	INIT_LIST_HEAD(&urb_p->urb_entry);
+	return urb_p;
+}
+
+static void free_urbp(struct urbp *urb_p)
+{
+	kfree(urb_p);
+}
+
+void free_urbp_and_urb(struct urbp *urb_p)
+{
+	if (!urb_p)
+		return;
+	free_urb(urb_p->urb);
+	free_urbp(urb_p);
+}
+
+
+/* utilities ; almost verbatim from dummy_hcd.c */
+
+/* called with spinlock held */
+static void nuke(struct vudc *udc, struct vep *ep)
+{
+	struct vrequest	*req;
+
+	while (!list_empty(&ep->req_queue)) {
+		req = list_first_entry(&ep->req_queue, struct vrequest,
+				       req_entry);
+		list_del_init(&req->req_entry);
+		req->req.status = -ESHUTDOWN;
+
+		spin_unlock(&udc->lock);
+		usb_gadget_giveback_request(&ep->ep, &req->req);
+		spin_lock(&udc->lock);
+	}
+}
+
+/* caller must hold lock */
+static void stop_activity(struct vudc *udc)
+{
+	int i;
+	struct urbp *urb_p, *tmp;
+
+	udc->address = 0;
+
+	for (i = 0; i < VIRTUAL_ENDPOINTS; i++)
+		nuke(udc, &udc->ep[i]);
+
+	list_for_each_entry_safe(urb_p, tmp, &udc->urb_queue, urb_entry) {
+		list_del(&urb_p->urb_entry);
+		free_urbp_and_urb(urb_p);
+	}
+}
+
+struct vep *vudc_find_endpoint(struct vudc *udc, u8 address)
+{
+	int i;
+
+	if ((address & ~USB_DIR_IN) == 0)
+		return &udc->ep[0];
+
+	for (i = 1; i < VIRTUAL_ENDPOINTS; i++) {
+		struct vep *ep = &udc->ep[i];
+
+		if (!ep->desc)
+			continue;
+		if (ep->desc->bEndpointAddress == address)
+			return ep;
+	}
+	return NULL;
+}
+
+/* gadget ops */
+
+static int vgadget_get_frame(struct usb_gadget *_gadget)
+{
+	struct timespec64 now;
+	struct vudc *udc = usb_gadget_to_vudc(_gadget);
+
+	ktime_get_ts64(&now);
+	return ((now.tv_sec - udc->start_time.tv_sec) * 1000 +
+		(now.tv_nsec - udc->start_time.tv_nsec) / NSEC_PER_MSEC)
+			& 0x7FF;
+}
+
+static int vgadget_set_selfpowered(struct usb_gadget *_gadget, int value)
+{
+	struct vudc *udc = usb_gadget_to_vudc(_gadget);
+
+	if (value)
+		udc->devstatus |= (1 << USB_DEVICE_SELF_POWERED);
+	else
+		udc->devstatus &= ~(1 << USB_DEVICE_SELF_POWERED);
+	return 0;
+}
+
+static int vgadget_pullup(struct usb_gadget *_gadget, int value)
+{
+	struct vudc *udc = usb_gadget_to_vudc(_gadget);
+	unsigned long flags;
+	int ret;
+
+
+	spin_lock_irqsave(&udc->lock, flags);
+	value = !!value;
+	if (value == udc->pullup)
+		goto unlock;
+
+	udc->pullup = value;
+	if (value) {
+		udc->gadget.speed = min_t(u8, USB_SPEED_HIGH,
+					   udc->driver->max_speed);
+		udc->ep[0].ep.maxpacket = 64;
+		/*
+		 * This is the first place where we can ask our
+		 * gadget driver for descriptors.
+		 */
+		ret = get_gadget_descs(udc);
+		if (ret) {
+			dev_err(&udc->gadget.dev, "Unable go get desc: %d", ret);
+			goto unlock;
+		}
+
+		spin_unlock_irqrestore(&udc->lock, flags);
+		usbip_start_eh(&udc->ud);
+	} else {
+		/* Invalidate descriptors */
+		udc->desc_cached = 0;
+
+		spin_unlock_irqrestore(&udc->lock, flags);
+		usbip_event_add(&udc->ud, VUDC_EVENT_REMOVED);
+		usbip_stop_eh(&udc->ud); /* Wait for eh completion */
+	}
+
+	return 0;
+
+unlock:
+	spin_unlock_irqrestore(&udc->lock, flags);
+	return 0;
+}
+
+static int vgadget_udc_start(struct usb_gadget *g,
+		struct usb_gadget_driver *driver)
+{
+	struct vudc *udc = usb_gadget_to_vudc(g);
+	unsigned long flags;
+
+	spin_lock_irqsave(&udc->lock, flags);
+	udc->driver = driver;
+	udc->pullup = udc->connected = udc->desc_cached = 0;
+	spin_unlock_irqrestore(&udc->lock, flags);
+
+	return 0;
+}
+
+static int vgadget_udc_stop(struct usb_gadget *g)
+{
+	struct vudc *udc = usb_gadget_to_vudc(g);
+	unsigned long flags;
+
+	spin_lock_irqsave(&udc->lock, flags);
+	udc->driver = NULL;
+	spin_unlock_irqrestore(&udc->lock, flags);
+	return 0;
+}
+
+static const struct usb_gadget_ops vgadget_ops = {
+	.get_frame	= vgadget_get_frame,
+	.set_selfpowered = vgadget_set_selfpowered,
+	.pullup		= vgadget_pullup,
+	.udc_start	= vgadget_udc_start,
+	.udc_stop	= vgadget_udc_stop,
+};
+
+
+/* endpoint ops */
+
+static int vep_enable(struct usb_ep *_ep,
+		const struct usb_endpoint_descriptor *desc)
+{
+	struct vep	*ep;
+	struct vudc	*udc;
+	unsigned int	maxp;
+	unsigned long	flags;
+
+	ep = to_vep(_ep);
+	udc = ep_to_vudc(ep);
+
+	if (!_ep || !desc || ep->desc || _ep->caps.type_control
+			|| desc->bDescriptorType != USB_DT_ENDPOINT)
+		return -EINVAL;
+
+	if (!udc->driver)
+		return -ESHUTDOWN;
+
+	spin_lock_irqsave(&udc->lock, flags);
+
+	maxp = usb_endpoint_maxp(desc);
+	_ep->maxpacket = maxp;
+	ep->desc = desc;
+	ep->type = usb_endpoint_type(desc);
+	ep->halted = ep->wedged = 0;
+
+	spin_unlock_irqrestore(&udc->lock, flags);
+
+	return 0;
+}
+
+static int vep_disable(struct usb_ep *_ep)
+{
+	struct vep *ep;
+	struct vudc *udc;
+	unsigned long flags;
+
+	ep = to_vep(_ep);
+	udc = ep_to_vudc(ep);
+	if (!_ep || !ep->desc || _ep->caps.type_control)
+		return -EINVAL;
+
+	spin_lock_irqsave(&udc->lock, flags);
+	ep->desc = NULL;
+	nuke(udc, ep);
+	spin_unlock_irqrestore(&udc->lock, flags);
+
+	return 0;
+}
+
+static struct usb_request *vep_alloc_request(struct usb_ep *_ep,
+		gfp_t mem_flags)
+{
+	struct vrequest *req;
+
+	if (!_ep)
+		return NULL;
+
+	req = kzalloc(sizeof(*req), mem_flags);
+	if (!req)
+		return NULL;
+
+	INIT_LIST_HEAD(&req->req_entry);
+
+	return &req->req;
+}
+
+static void vep_free_request(struct usb_ep *_ep, struct usb_request *_req)
+{
+	struct vrequest *req;
+
+	if (WARN_ON(!_ep || !_req))
+		return;
+
+	req = to_vrequest(_req);
+	kfree(req);
+}
+
+static int vep_queue(struct usb_ep *_ep, struct usb_request *_req,
+		gfp_t mem_flags)
+{
+	struct vep *ep;
+	struct vrequest *req;
+	struct vudc *udc;
+	unsigned long flags;
+
+	if (!_ep || !_req)
+		return -EINVAL;
+
+	ep = to_vep(_ep);
+	req = to_vrequest(_req);
+	udc = ep_to_vudc(ep);
+
+	spin_lock_irqsave(&udc->lock, flags);
+	_req->actual = 0;
+	_req->status = -EINPROGRESS;
+
+	list_add_tail(&req->req_entry, &ep->req_queue);
+	spin_unlock_irqrestore(&udc->lock, flags);
+
+	return 0;
+}
+
+static int vep_dequeue(struct usb_ep *_ep, struct usb_request *_req)
+{
+	struct vep *ep;
+	struct vrequest *req;
+	struct vudc *udc;
+	struct vrequest *lst;
+	unsigned long flags;
+	int ret = -EINVAL;
+
+	if (!_ep || !_req)
+		return ret;
+
+	ep = to_vep(_ep);
+	req = to_vrequest(_req);
+	udc = req->udc;
+
+	if (!udc->driver)
+		return -ESHUTDOWN;
+
+	spin_lock_irqsave(&udc->lock, flags);
+	list_for_each_entry(lst, &ep->req_queue, req_entry) {
+		if (&lst->req == _req) {
+			list_del_init(&lst->req_entry);
+			_req->status = -ECONNRESET;
+			ret = 0;
+			break;
+		}
+	}
+	spin_unlock_irqrestore(&udc->lock, flags);
+
+	if (ret == 0)
+		usb_gadget_giveback_request(_ep, _req);
+
+	return ret;
+}
+
+static int
+vep_set_halt_and_wedge(struct usb_ep *_ep, int value, int wedged)
+{
+	struct vep *ep;
+	struct vudc *udc;
+	unsigned long flags;
+	int ret = 0;
+
+	ep = to_vep(_ep);
+	if (!_ep)
+		return -EINVAL;
+
+	udc = ep_to_vudc(ep);
+	if (!udc->driver)
+		return -ESHUTDOWN;
+
+	spin_lock_irqsave(&udc->lock, flags);
+	if (!value)
+		ep->halted = ep->wedged = 0;
+	else if (ep->desc && (ep->desc->bEndpointAddress & USB_DIR_IN) &&
+			!list_empty(&ep->req_queue))
+		ret = -EAGAIN;
+	else {
+		ep->halted = 1;
+		if (wedged)
+			ep->wedged = 1;
+	}
+
+	spin_unlock_irqrestore(&udc->lock, flags);
+	return ret;
+}
+
+static int
+vep_set_halt(struct usb_ep *_ep, int value)
+{
+	return vep_set_halt_and_wedge(_ep, value, 0);
+}
+
+static int vep_set_wedge(struct usb_ep *_ep)
+{
+	return vep_set_halt_and_wedge(_ep, 1, 1);
+}
+
+static const struct usb_ep_ops vep_ops = {
+	.enable		= vep_enable,
+	.disable	= vep_disable,
+
+	.alloc_request	= vep_alloc_request,
+	.free_request	= vep_free_request,
+
+	.queue		= vep_queue,
+	.dequeue	= vep_dequeue,
+
+	.set_halt	= vep_set_halt,
+	.set_wedge	= vep_set_wedge,
+};
+
+
+/* shutdown / reset / error handlers */
+
+static void vudc_shutdown(struct usbip_device *ud)
+{
+	struct vudc *udc = container_of(ud, struct vudc, ud);
+	int call_disconnect = 0;
+	unsigned long flags;
+
+	dev_dbg(&udc->pdev->dev, "device shutdown");
+	if (ud->tcp_socket)
+		kernel_sock_shutdown(ud->tcp_socket, SHUT_RDWR);
+
+	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;
+	}
+
+	if (ud->tcp_socket) {
+		sockfd_put(ud->tcp_socket);
+		ud->tcp_socket = NULL;
+	}
+
+	spin_lock_irqsave(&udc->lock, flags);
+	stop_activity(udc);
+	if (udc->connected && udc->driver->disconnect)
+		call_disconnect = 1;
+	udc->connected = 0;
+	spin_unlock_irqrestore(&udc->lock, flags);
+	if (call_disconnect)
+		udc->driver->disconnect(&udc->gadget);
+}
+
+static void vudc_device_reset(struct usbip_device *ud)
+{
+	struct vudc *udc = container_of(ud, struct vudc, ud);
+	unsigned long flags;
+
+	dev_dbg(&udc->pdev->dev, "device reset");
+	spin_lock_irqsave(&udc->lock, flags);
+	stop_activity(udc);
+	spin_unlock_irqrestore(&udc->lock, flags);
+	if (udc->driver)
+		usb_gadget_udc_reset(&udc->gadget, udc->driver);
+	spin_lock_irqsave(&ud->lock, flags);
+	ud->status = SDEV_ST_AVAILABLE;
+	spin_unlock_irqrestore(&ud->lock, flags);
+}
+
+static void vudc_device_unusable(struct usbip_device *ud)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&ud->lock, flags);
+	ud->status = SDEV_ST_ERROR;
+	spin_unlock_irqrestore(&ud->lock, flags);
+}
+
+/* device setup / cleanup */
+
+struct vudc_device *alloc_vudc_device(int devid)
+{
+	struct vudc_device *udc_dev = NULL;
+
+	udc_dev = kzalloc(sizeof(*udc_dev), GFP_KERNEL);
+	if (!udc_dev)
+		goto out;
+
+	INIT_LIST_HEAD(&udc_dev->dev_entry);
+
+	udc_dev->pdev = platform_device_alloc(GADGET_NAME, devid);
+	if (!udc_dev->pdev) {
+		kfree(udc_dev);
+		udc_dev = NULL;
+	}
+
+out:
+	return udc_dev;
+}
+
+void put_vudc_device(struct vudc_device *udc_dev)
+{
+	platform_device_put(udc_dev->pdev);
+	kfree(udc_dev);
+}
+
+static int init_vudc_hw(struct vudc *udc)
+{
+	int i;
+	struct usbip_device *ud = &udc->ud;
+	struct vep *ep;
+
+	udc->ep = kcalloc(VIRTUAL_ENDPOINTS, sizeof(*udc->ep), GFP_KERNEL);
+	if (!udc->ep)
+		goto nomem_ep;
+
+	INIT_LIST_HEAD(&udc->gadget.ep_list);
+
+	/* create ep0 and 15 in, 15 out general purpose eps */
+	for (i = 0; i < VIRTUAL_ENDPOINTS; ++i) {
+		int is_out = i % 2;
+		int num = (i + 1) / 2;
+
+		ep = &udc->ep[i];
+
+		sprintf(ep->name, "ep%d%s", num,
+			i ? (is_out ? "out" : "in") : "");
+		ep->ep.name = ep->name;
+
+		ep->ep.ops = &vep_ops;
+
+		usb_ep_set_maxpacket_limit(&ep->ep, ~0);
+		ep->ep.max_streams = 16;
+		ep->gadget = &udc->gadget;
+		INIT_LIST_HEAD(&ep->req_queue);
+
+		if (i == 0) {
+			/* ep0 */
+			ep->ep.caps.type_control = true;
+			ep->ep.caps.dir_out = true;
+			ep->ep.caps.dir_in = true;
+
+			udc->gadget.ep0 = &ep->ep;
+		} else {
+			/* All other eps */
+			ep->ep.caps.type_iso = true;
+			ep->ep.caps.type_int = true;
+			ep->ep.caps.type_bulk = true;
+
+			if (is_out)
+				ep->ep.caps.dir_out = true;
+			else
+				ep->ep.caps.dir_in = true;
+
+			list_add_tail(&ep->ep.ep_list, &udc->gadget.ep_list);
+		}
+	}
+
+	spin_lock_init(&udc->lock);
+	spin_lock_init(&udc->lock_tx);
+	INIT_LIST_HEAD(&udc->urb_queue);
+	INIT_LIST_HEAD(&udc->tx_queue);
+	init_waitqueue_head(&udc->tx_waitq);
+
+	spin_lock_init(&ud->lock);
+	mutex_init(&ud->sysfs_lock);
+	ud->status = SDEV_ST_AVAILABLE;
+	ud->side = USBIP_VUDC;
+
+	ud->eh_ops.shutdown = vudc_shutdown;
+	ud->eh_ops.reset    = vudc_device_reset;
+	ud->eh_ops.unusable = vudc_device_unusable;
+
+	v_init_timer(udc);
+	return 0;
+
+nomem_ep:
+		return -ENOMEM;
+}
+
+static void cleanup_vudc_hw(struct vudc *udc)
+{
+	kfree(udc->ep);
+}
+
+/* platform driver ops */
+
+int vudc_probe(struct platform_device *pdev)
+{
+	struct vudc *udc;
+	int ret = -ENOMEM;
+
+	udc = kzalloc(sizeof(*udc), GFP_KERNEL);
+	if (!udc)
+		goto out;
+
+	udc->gadget.name = GADGET_NAME;
+	udc->gadget.ops = &vgadget_ops;
+	udc->gadget.max_speed = USB_SPEED_HIGH;
+	udc->gadget.dev.parent = &pdev->dev;
+	udc->pdev = pdev;
+
+	ret = init_vudc_hw(udc);
+	if (ret)
+		goto err_init_vudc_hw;
+
+	ret = usb_add_gadget_udc(&pdev->dev, &udc->gadget);
+	if (ret < 0)
+		goto err_add_udc;
+
+	ret = sysfs_create_group(&pdev->dev.kobj, &vudc_attr_group);
+	if (ret) {
+		dev_err(&udc->pdev->dev, "create sysfs files\n");
+		goto err_sysfs;
+	}
+
+	platform_set_drvdata(pdev, udc);
+
+	return ret;
+
+err_sysfs:
+	usb_del_gadget_udc(&udc->gadget);
+err_add_udc:
+	cleanup_vudc_hw(udc);
+err_init_vudc_hw:
+	kfree(udc);
+out:
+	return ret;
+}
+
+int vudc_remove(struct platform_device *pdev)
+{
+	struct vudc *udc = platform_get_drvdata(pdev);
+
+	sysfs_remove_group(&pdev->dev.kobj, &vudc_attr_group);
+	usb_del_gadget_udc(&udc->gadget);
+	cleanup_vudc_hw(udc);
+	kfree(udc);
+	return 0;
+}
diff --git a/drivers/usb/usbip/vudc_main.c b/drivers/usb/usbip/vudc_main.c
new file mode 100644
index 000000000..390733e69
--- /dev/null
+++ b/drivers/usb/usbip/vudc_main.c
@@ -0,0 +1,109 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (C) 2015 Karol Kosik <karo9@interia.eu>
+ * Copyright (C) 2015-2016 Samsung Electronics
+ *               Igor Kotrasinski <i.kotrasinsk@samsung.com>
+ *               Krzysztof Opasiak <k.opasiak@samsung.com>
+ */
+
+#include <linux/device.h>
+#include <linux/list.h>
+#include <linux/module.h>
+
+#include "vudc.h"
+
+static unsigned int vudc_number = 1;
+
+module_param_named(num, vudc_number, uint, S_IRUGO);
+MODULE_PARM_DESC(num, "number of emulated controllers");
+
+static struct platform_driver vudc_driver = {
+	.probe		= vudc_probe,
+	.remove		= vudc_remove,
+	.driver		= {
+		.name	= GADGET_NAME,
+	},
+};
+
+static struct list_head vudc_devices = LIST_HEAD_INIT(vudc_devices);
+
+static int __init init(void)
+{
+	int retval = -ENOMEM;
+	int i;
+	struct vudc_device *udc_dev = NULL, *udc_dev2 = NULL;
+
+	if (usb_disabled())
+		return -ENODEV;
+
+	if (vudc_number < 1) {
+		pr_err("Number of emulated UDC must be no less than 1");
+		return -EINVAL;
+	}
+
+	retval = platform_driver_register(&vudc_driver);
+	if (retval < 0)
+		goto out;
+
+	for (i = 0; i < vudc_number; i++) {
+		udc_dev = alloc_vudc_device(i);
+		if (!udc_dev) {
+			retval = -ENOMEM;
+			goto cleanup;
+		}
+
+		retval = platform_device_add(udc_dev->pdev);
+		if (retval < 0) {
+			put_vudc_device(udc_dev);
+			goto cleanup;
+		}
+
+		list_add_tail(&udc_dev->dev_entry, &vudc_devices);
+		if (!platform_get_drvdata(udc_dev->pdev)) {
+			/*
+			 * The udc was added successfully but its probe
+			 * function failed for some reason.
+			 */
+			retval = -EINVAL;
+			goto cleanup;
+		}
+	}
+	goto out;
+
+cleanup:
+	list_for_each_entry_safe(udc_dev, udc_dev2, &vudc_devices, dev_entry) {
+		list_del(&udc_dev->dev_entry);
+		/*
+		 * Just do platform_device_del() here, put_vudc_device()
+		 * calls the platform_device_put()
+		 */
+		platform_device_del(udc_dev->pdev);
+		put_vudc_device(udc_dev);
+	}
+
+	platform_driver_unregister(&vudc_driver);
+out:
+	return retval;
+}
+module_init(init);
+
+static void __exit cleanup(void)
+{
+	struct vudc_device *udc_dev = NULL, *udc_dev2 = NULL;
+
+	list_for_each_entry_safe(udc_dev, udc_dev2, &vudc_devices, dev_entry) {
+		list_del(&udc_dev->dev_entry);
+		/*
+		 * Just do platform_device_del() here, put_vudc_device()
+		 * calls the platform_device_put()
+		 */
+		platform_device_del(udc_dev->pdev);
+		put_vudc_device(udc_dev);
+	}
+	platform_driver_unregister(&vudc_driver);
+}
+module_exit(cleanup);
+
+MODULE_DESCRIPTION("USB over IP Device Controller");
+MODULE_AUTHOR("Krzysztof Opasiak, Karol Kosik, Igor Kotrasinski");
+MODULE_LICENSE("GPL");
diff --git a/drivers/usb/usbip/vudc_rx.c b/drivers/usb/usbip/vudc_rx.c
new file mode 100644
index 000000000..1e8a23d92
--- /dev/null
+++ b/drivers/usb/usbip/vudc_rx.c
@@ -0,0 +1,241 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (C) 2015 Karol Kosik <karo9@interia.eu>
+ * Copyright (C) 2015-2016 Samsung Electronics
+ *               Igor Kotrasinski <i.kotrasinsk@samsung.com>
+ */
+
+#include <net/sock.h>
+#include <linux/list.h>
+#include <linux/kthread.h>
+
+#include "usbip_common.h"
+#include "vudc.h"
+
+static int alloc_urb_from_cmd(struct urb **urbp,
+			      struct usbip_header *pdu, u8 type)
+{
+	struct urb *urb;
+
+	if (type == USB_ENDPOINT_XFER_ISOC)
+		urb = usb_alloc_urb(pdu->u.cmd_submit.number_of_packets,
+					  GFP_KERNEL);
+	else
+		urb = usb_alloc_urb(0, GFP_KERNEL);
+
+	if (!urb)
+		goto err;
+
+	usbip_pack_pdu(pdu, urb, USBIP_CMD_SUBMIT, 0);
+
+	if (urb->transfer_buffer_length > 0) {
+		urb->transfer_buffer = kzalloc(urb->transfer_buffer_length,
+			GFP_KERNEL);
+		if (!urb->transfer_buffer)
+			goto free_urb;
+	}
+
+	urb->setup_packet = kmemdup(&pdu->u.cmd_submit.setup, 8,
+			    GFP_KERNEL);
+	if (!urb->setup_packet)
+		goto free_buffer;
+
+	/*
+	 * FIXME - we only setup pipe enough for usbip functions
+	 * to behave nicely
+	 */
+	urb->pipe |= pdu->base.direction == USBIP_DIR_IN ?
+			USB_DIR_IN : USB_DIR_OUT;
+
+	*urbp = urb;
+	return 0;
+
+free_buffer:
+	kfree(urb->transfer_buffer);
+	urb->transfer_buffer = NULL;
+free_urb:
+	usb_free_urb(urb);
+err:
+	return -ENOMEM;
+}
+
+static int v_recv_cmd_unlink(struct vudc *udc,
+				struct usbip_header *pdu)
+{
+	unsigned long flags;
+	struct urbp *urb_p;
+
+	spin_lock_irqsave(&udc->lock, flags);
+	list_for_each_entry(urb_p, &udc->urb_queue, urb_entry) {
+		if (urb_p->seqnum != pdu->u.cmd_unlink.seqnum)
+			continue;
+		urb_p->urb->unlinked = -ECONNRESET;
+		urb_p->seqnum = pdu->base.seqnum;
+		v_kick_timer(udc, jiffies);
+		spin_unlock_irqrestore(&udc->lock, flags);
+		return 0;
+	}
+	/* Not found, completed / not queued */
+	spin_lock(&udc->lock_tx);
+	v_enqueue_ret_unlink(udc, pdu->base.seqnum, 0);
+	wake_up(&udc->tx_waitq);
+	spin_unlock(&udc->lock_tx);
+	spin_unlock_irqrestore(&udc->lock, flags);
+
+	return 0;
+}
+
+static int v_recv_cmd_submit(struct vudc *udc,
+				 struct usbip_header *pdu)
+{
+	int ret = 0;
+	struct urbp *urb_p;
+	u8 address;
+	unsigned long flags;
+
+	urb_p = alloc_urbp();
+	if (!urb_p) {
+		usbip_event_add(&udc->ud, VUDC_EVENT_ERROR_MALLOC);
+		return -ENOMEM;
+	}
+
+	/* base.ep is pipeendpoint(pipe) */
+	address = pdu->base.ep;
+	if (pdu->base.direction == USBIP_DIR_IN)
+		address |= USB_DIR_IN;
+
+	spin_lock_irq(&udc->lock);
+	urb_p->ep = vudc_find_endpoint(udc, address);
+	if (!urb_p->ep) {
+		/* we don't know the type, there may be isoc data! */
+		dev_err(&udc->pdev->dev, "request to nonexistent endpoint");
+		spin_unlock_irq(&udc->lock);
+		usbip_event_add(&udc->ud, VUDC_EVENT_ERROR_TCP);
+		ret = -EPIPE;
+		goto free_urbp;
+	}
+	urb_p->type = urb_p->ep->type;
+	spin_unlock_irq(&udc->lock);
+
+	urb_p->new = 1;
+	urb_p->seqnum = pdu->base.seqnum;
+
+	if (urb_p->ep->type == USB_ENDPOINT_XFER_ISOC) {
+		/* validate packet size and number of packets */
+		unsigned int maxp, packets, bytes;
+
+		maxp = usb_endpoint_maxp(urb_p->ep->desc);
+		maxp *= usb_endpoint_maxp_mult(urb_p->ep->desc);
+		bytes = pdu->u.cmd_submit.transfer_buffer_length;
+		packets = DIV_ROUND_UP(bytes, maxp);
+
+		if (pdu->u.cmd_submit.number_of_packets < 0 ||
+		    pdu->u.cmd_submit.number_of_packets > packets) {
+			dev_err(&udc->gadget.dev,
+				"CMD_SUBMIT: isoc invalid num packets %d\n",
+				pdu->u.cmd_submit.number_of_packets);
+			ret = -EMSGSIZE;
+			goto free_urbp;
+		}
+	}
+
+	ret = alloc_urb_from_cmd(&urb_p->urb, pdu, urb_p->ep->type);
+	if (ret) {
+		usbip_event_add(&udc->ud, VUDC_EVENT_ERROR_MALLOC);
+		ret = -ENOMEM;
+		goto free_urbp;
+	}
+
+	urb_p->urb->status = -EINPROGRESS;
+
+	/* FIXME: more pipe setup to please usbip_common */
+	urb_p->urb->pipe &= ~(3 << 30);
+	switch (urb_p->ep->type) {
+	case USB_ENDPOINT_XFER_BULK:
+		urb_p->urb->pipe |= (PIPE_BULK << 30);
+		break;
+	case USB_ENDPOINT_XFER_INT:
+		urb_p->urb->pipe |= (PIPE_INTERRUPT << 30);
+		break;
+	case USB_ENDPOINT_XFER_CONTROL:
+		urb_p->urb->pipe |= (PIPE_CONTROL << 30);
+		break;
+	case USB_ENDPOINT_XFER_ISOC:
+		urb_p->urb->pipe |= (PIPE_ISOCHRONOUS << 30);
+		break;
+	}
+	ret = usbip_recv_xbuff(&udc->ud, urb_p->urb);
+	if (ret < 0)
+		goto free_urbp;
+
+	ret = usbip_recv_iso(&udc->ud, urb_p->urb);
+	if (ret < 0)
+		goto free_urbp;
+
+	spin_lock_irqsave(&udc->lock, flags);
+	v_kick_timer(udc, jiffies);
+	list_add_tail(&urb_p->urb_entry, &udc->urb_queue);
+	spin_unlock_irqrestore(&udc->lock, flags);
+
+	return 0;
+
+free_urbp:
+	free_urbp_and_urb(urb_p);
+	return ret;
+}
+
+static int v_rx_pdu(struct usbip_device *ud)
+{
+	int ret;
+	struct usbip_header pdu;
+	struct vudc *udc = container_of(ud, struct vudc, ud);
+
+	memset(&pdu, 0, sizeof(pdu));
+	ret = usbip_recv(ud->tcp_socket, &pdu, sizeof(pdu));
+	if (ret != sizeof(pdu)) {
+		usbip_event_add(ud, VUDC_EVENT_ERROR_TCP);
+		if (ret >= 0)
+			return -EPIPE;
+		return ret;
+	}
+	usbip_header_correct_endian(&pdu, 0);
+
+	spin_lock_irq(&ud->lock);
+	ret = (ud->status == SDEV_ST_USED);
+	spin_unlock_irq(&ud->lock);
+	if (!ret) {
+		usbip_event_add(ud, VUDC_EVENT_ERROR_TCP);
+		return -EBUSY;
+	}
+
+	switch (pdu.base.command) {
+	case USBIP_CMD_UNLINK:
+		ret = v_recv_cmd_unlink(udc, &pdu);
+		break;
+	case USBIP_CMD_SUBMIT:
+		ret = v_recv_cmd_submit(udc, &pdu);
+		break;
+	default:
+		ret = -EPIPE;
+		pr_err("rx: unknown command");
+		break;
+	}
+	return ret;
+}
+
+int v_rx_loop(void *data)
+{
+	struct usbip_device *ud = data;
+	int ret = 0;
+
+	while (!kthread_should_stop()) {
+		if (usbip_event_happened(ud))
+			break;
+		ret = v_rx_pdu(ud);
+		if (ret < 0) {
+			pr_warn("v_rx exit with error %d", ret);
+			break;
+		}
+	}
+	return ret;
+}
diff --git a/drivers/usb/usbip/vudc_sysfs.c b/drivers/usb/usbip/vudc_sysfs.c
new file mode 100644
index 000000000..7b1437a51
--- /dev/null
+++ b/drivers/usb/usbip/vudc_sysfs.c
@@ -0,0 +1,264 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (C) 2015 Karol Kosik <karo9@interia.eu>
+ * Copyright (C) 2015-2016 Samsung Electronics
+ *               Igor Kotrasinski <i.kotrasinsk@samsung.com>
+ *               Krzysztof Opasiak <k.opasiak@samsung.com>
+ */
+
+#include <linux/device.h>
+#include <linux/list.h>
+#include <linux/usb/gadget.h>
+#include <linux/usb/ch9.h>
+#include <linux/sysfs.h>
+#include <linux/kthread.h>
+#include <linux/file.h>
+#include <linux/byteorder/generic.h>
+
+#include "usbip_common.h"
+#include "vudc.h"
+
+#include <net/sock.h>
+
+/* called with udc->lock held */
+int get_gadget_descs(struct vudc *udc)
+{
+	struct vrequest *usb_req;
+	struct vep *ep0 = to_vep(udc->gadget.ep0);
+	struct usb_device_descriptor *ddesc = &udc->dev_desc;
+	struct usb_ctrlrequest req;
+	int ret;
+
+	if (!udc->driver || !udc->pullup)
+		return -EINVAL;
+
+	req.bRequestType = USB_DIR_IN | USB_TYPE_STANDARD | USB_RECIP_DEVICE;
+	req.bRequest = USB_REQ_GET_DESCRIPTOR;
+	req.wValue = cpu_to_le16(USB_DT_DEVICE << 8);
+	req.wIndex = cpu_to_le16(0);
+	req.wLength = cpu_to_le16(sizeof(*ddesc));
+
+	spin_unlock(&udc->lock);
+	ret = udc->driver->setup(&(udc->gadget), &req);
+	spin_lock(&udc->lock);
+	if (ret < 0)
+		goto out;
+
+	/* assuming request queue is empty; request is now on top */
+	usb_req = list_last_entry(&ep0->req_queue, struct vrequest, req_entry);
+	list_del(&usb_req->req_entry);
+
+	if (usb_req->req.length > sizeof(*ddesc)) {
+		ret = -EOVERFLOW;
+		goto giveback_req;
+	}
+
+	memcpy(ddesc, usb_req->req.buf, sizeof(*ddesc));
+	udc->desc_cached = 1;
+	ret = 0;
+giveback_req:
+	usb_req->req.status = 0;
+	usb_req->req.actual = usb_req->req.length;
+	usb_gadget_giveback_request(&(ep0->ep), &(usb_req->req));
+out:
+	return ret;
+}
+
+/*
+ * Exposes device descriptor from the gadget driver.
+ */
+static ssize_t dev_desc_read(struct file *file, struct kobject *kobj,
+			     struct bin_attribute *attr, char *out,
+			     loff_t off, size_t count)
+{
+	struct device *dev = kobj_to_dev(kobj);
+	struct vudc *udc = (struct vudc *)dev_get_drvdata(dev);
+	char *desc_ptr = (char *) &udc->dev_desc;
+	unsigned long flags;
+	int ret;
+
+	spin_lock_irqsave(&udc->lock, flags);
+	if (!udc->desc_cached) {
+		ret = -ENODEV;
+		goto unlock;
+	}
+
+	memcpy(out, desc_ptr + off, count);
+	ret = count;
+unlock:
+	spin_unlock_irqrestore(&udc->lock, flags);
+	return ret;
+}
+static BIN_ATTR_RO(dev_desc, sizeof(struct usb_device_descriptor));
+
+static ssize_t usbip_sockfd_store(struct device *dev,
+				  struct device_attribute *attr,
+				  const char *in, size_t count)
+{
+	struct vudc *udc = (struct vudc *) dev_get_drvdata(dev);
+	int rv;
+	int sockfd = 0;
+	int err;
+	struct socket *socket;
+	unsigned long flags;
+	int ret;
+	struct task_struct *tcp_rx = NULL;
+	struct task_struct *tcp_tx = NULL;
+
+	rv = kstrtoint(in, 0, &sockfd);
+	if (rv != 0)
+		return -EINVAL;
+
+	if (!udc) {
+		dev_err(dev, "no device");
+		return -ENODEV;
+	}
+	mutex_lock(&udc->ud.sysfs_lock);
+	spin_lock_irqsave(&udc->lock, flags);
+	/* Don't export what we don't have */
+	if (!udc->driver || !udc->pullup) {
+		dev_err(dev, "gadget not bound");
+		ret = -ENODEV;
+		goto unlock;
+	}
+
+	if (sockfd != -1) {
+		if (udc->connected) {
+			dev_err(dev, "Device already connected");
+			ret = -EBUSY;
+			goto unlock;
+		}
+
+		spin_lock_irq(&udc->ud.lock);
+
+		if (udc->ud.status != SDEV_ST_AVAILABLE) {
+			ret = -EINVAL;
+			goto unlock_ud;
+		}
+
+		socket = sockfd_lookup(sockfd, &err);
+		if (!socket) {
+			dev_err(dev, "failed to lookup sock");
+			ret = -EINVAL;
+			goto unlock_ud;
+		}
+
+		if (socket->type != SOCK_STREAM) {
+			dev_err(dev, "Expecting SOCK_STREAM - found %d",
+				socket->type);
+			ret = -EINVAL;
+			goto sock_err;
+		}
+
+		/* unlock and create threads and get tasks */
+		spin_unlock_irq(&udc->ud.lock);
+		spin_unlock_irqrestore(&udc->lock, flags);
+
+		tcp_rx = kthread_create(&v_rx_loop, &udc->ud, "vudc_rx");
+		if (IS_ERR(tcp_rx)) {
+			sockfd_put(socket);
+			mutex_unlock(&udc->ud.sysfs_lock);
+			return -EINVAL;
+		}
+		tcp_tx = kthread_create(&v_tx_loop, &udc->ud, "vudc_tx");
+		if (IS_ERR(tcp_tx)) {
+			kthread_stop(tcp_rx);
+			sockfd_put(socket);
+			mutex_unlock(&udc->ud.sysfs_lock);
+			return -EINVAL;
+		}
+
+		/* get task structs now */
+		get_task_struct(tcp_rx);
+		get_task_struct(tcp_tx);
+
+		/* lock and update udc->ud state */
+		spin_lock_irqsave(&udc->lock, flags);
+		spin_lock_irq(&udc->ud.lock);
+
+		udc->ud.tcp_socket = socket;
+		udc->ud.tcp_rx = tcp_rx;
+		udc->ud.tcp_tx = tcp_tx;
+		udc->ud.status = SDEV_ST_USED;
+
+		spin_unlock_irq(&udc->ud.lock);
+
+		ktime_get_ts64(&udc->start_time);
+		v_start_timer(udc);
+		udc->connected = 1;
+
+		spin_unlock_irqrestore(&udc->lock, flags);
+
+		wake_up_process(udc->ud.tcp_rx);
+		wake_up_process(udc->ud.tcp_tx);
+
+		mutex_unlock(&udc->ud.sysfs_lock);
+		return count;
+
+	} else {
+		if (!udc->connected) {
+			dev_err(dev, "Device not connected");
+			ret = -EINVAL;
+			goto unlock;
+		}
+
+		spin_lock_irq(&udc->ud.lock);
+		if (udc->ud.status != SDEV_ST_USED) {
+			ret = -EINVAL;
+			goto unlock_ud;
+		}
+		spin_unlock_irq(&udc->ud.lock);
+
+		usbip_event_add(&udc->ud, VUDC_EVENT_DOWN);
+	}
+
+	spin_unlock_irqrestore(&udc->lock, flags);
+	mutex_unlock(&udc->ud.sysfs_lock);
+
+	return count;
+
+sock_err:
+	sockfd_put(socket);
+unlock_ud:
+	spin_unlock_irq(&udc->ud.lock);
+unlock:
+	spin_unlock_irqrestore(&udc->lock, flags);
+	mutex_unlock(&udc->ud.sysfs_lock);
+
+	return ret;
+}
+static DEVICE_ATTR_WO(usbip_sockfd);
+
+static ssize_t usbip_status_show(struct device *dev,
+			       struct device_attribute *attr, char *out)
+{
+	struct vudc *udc = (struct vudc *) dev_get_drvdata(dev);
+	int status;
+
+	if (!udc) {
+		dev_err(dev, "no device");
+		return -ENODEV;
+	}
+	spin_lock_irq(&udc->ud.lock);
+	status = udc->ud.status;
+	spin_unlock_irq(&udc->ud.lock);
+
+	return snprintf(out, PAGE_SIZE, "%d\n", status);
+}
+static DEVICE_ATTR_RO(usbip_status);
+
+static struct attribute *dev_attrs[] = {
+	&dev_attr_usbip_sockfd.attr,
+	&dev_attr_usbip_status.attr,
+	NULL,
+};
+
+static struct bin_attribute *dev_bin_attrs[] = {
+	&bin_attr_dev_desc,
+	NULL,
+};
+
+const struct attribute_group vudc_attr_group = {
+	.attrs = dev_attrs,
+	.bin_attrs = dev_bin_attrs,
+};
diff --git a/drivers/usb/usbip/vudc_transfer.c b/drivers/usb/usbip/vudc_transfer.c
new file mode 100644
index 000000000..c9db846ee
--- /dev/null
+++ b/drivers/usb/usbip/vudc_transfer.c
@@ -0,0 +1,496 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (C) 2015 Karol Kosik <karo9@interia.eu>
+ * Copyright (C) 2015-2016 Samsung Electronics
+ *               Igor Kotrasinski <i.kotrasinsk@samsung.com>
+ *
+ * Based on dummy_hcd.c, which is:
+ * Copyright (C) 2003 David Brownell
+ * Copyright (C) 2003-2005 Alan Stern
+ */
+
+#include <linux/usb.h>
+#include <linux/timer.h>
+#include <linux/usb/ch9.h>
+
+#include "vudc.h"
+
+#define DEV_REQUEST	(USB_TYPE_STANDARD | USB_RECIP_DEVICE)
+#define DEV_INREQUEST	(DEV_REQUEST | USB_DIR_IN)
+#define INTF_REQUEST	(USB_TYPE_STANDARD | USB_RECIP_INTERFACE)
+#define INTF_INREQUEST	(INTF_REQUEST | USB_DIR_IN)
+#define EP_REQUEST	(USB_TYPE_STANDARD | USB_RECIP_ENDPOINT)
+#define EP_INREQUEST	(EP_REQUEST | USB_DIR_IN)
+
+static int get_frame_limit(enum usb_device_speed speed)
+{
+	switch (speed) {
+	case USB_SPEED_LOW:
+		return 8 /*bytes*/ * 12 /*packets*/;
+	case USB_SPEED_FULL:
+		return 64 /*bytes*/ * 19 /*packets*/;
+	case USB_SPEED_HIGH:
+		return 512 /*bytes*/ * 13 /*packets*/ * 8 /*uframes*/;
+	case USB_SPEED_SUPER:
+		/* Bus speed is 500000 bytes/ms, so use a little less */
+		return 490000;
+	default:
+		/* error */
+		return -1;
+	}
+
+}
+
+/*
+ * handle_control_request() - handles all control transfers
+ * @udc: pointer to vudc
+ * @urb: the urb request to handle
+ * @setup: pointer to the setup data for a USB device control
+ *	 request
+ * @status: pointer to request handling status
+ *
+ * Return 0 - if the request was handled
+ *	  1 - if the request wasn't handles
+ *	  error code on error
+ *
+ * Adapted from drivers/usb/gadget/udc/dummy_hcd.c
+ */
+static int handle_control_request(struct vudc *udc, struct urb *urb,
+				  struct usb_ctrlrequest *setup,
+				  int *status)
+{
+	struct vep	*ep2;
+	int		ret_val = 1;
+	unsigned int	w_index;
+	unsigned int	w_value;
+
+	w_index = le16_to_cpu(setup->wIndex);
+	w_value = le16_to_cpu(setup->wValue);
+	switch (setup->bRequest) {
+	case USB_REQ_SET_ADDRESS:
+		if (setup->bRequestType != DEV_REQUEST)
+			break;
+		udc->address = w_value;
+		ret_val = 0;
+		*status = 0;
+		break;
+	case USB_REQ_SET_FEATURE:
+		if (setup->bRequestType == DEV_REQUEST) {
+			ret_val = 0;
+			switch (w_value) {
+			case USB_DEVICE_REMOTE_WAKEUP:
+				break;
+			case USB_DEVICE_B_HNP_ENABLE:
+				udc->gadget.b_hnp_enable = 1;
+				break;
+			case USB_DEVICE_A_HNP_SUPPORT:
+				udc->gadget.a_hnp_support = 1;
+				break;
+			case USB_DEVICE_A_ALT_HNP_SUPPORT:
+				udc->gadget.a_alt_hnp_support = 1;
+				break;
+			default:
+				ret_val = -EOPNOTSUPP;
+			}
+			if (ret_val == 0) {
+				udc->devstatus |= (1 << w_value);
+				*status = 0;
+			}
+		} else if (setup->bRequestType == EP_REQUEST) {
+			/* endpoint halt */
+			ep2 = vudc_find_endpoint(udc, w_index);
+			if (!ep2 || ep2->ep.name == udc->ep[0].ep.name) {
+				ret_val = -EOPNOTSUPP;
+				break;
+			}
+			ep2->halted = 1;
+			ret_val = 0;
+			*status = 0;
+		}
+		break;
+	case USB_REQ_CLEAR_FEATURE:
+		if (setup->bRequestType == DEV_REQUEST) {
+			ret_val = 0;
+			switch (w_value) {
+			case USB_DEVICE_REMOTE_WAKEUP:
+				w_value = USB_DEVICE_REMOTE_WAKEUP;
+				break;
+
+			case USB_DEVICE_U1_ENABLE:
+			case USB_DEVICE_U2_ENABLE:
+			case USB_DEVICE_LTM_ENABLE:
+				ret_val = -EOPNOTSUPP;
+				break;
+			default:
+				ret_val = -EOPNOTSUPP;
+				break;
+			}
+			if (ret_val == 0) {
+				udc->devstatus &= ~(1 << w_value);
+				*status = 0;
+			}
+		} else if (setup->bRequestType == EP_REQUEST) {
+			/* endpoint halt */
+			ep2 = vudc_find_endpoint(udc, w_index);
+			if (!ep2) {
+				ret_val = -EOPNOTSUPP;
+				break;
+			}
+			if (!ep2->wedged)
+				ep2->halted = 0;
+			ret_val = 0;
+			*status = 0;
+		}
+		break;
+	case USB_REQ_GET_STATUS:
+		if (setup->bRequestType == DEV_INREQUEST
+				|| setup->bRequestType == INTF_INREQUEST
+				|| setup->bRequestType == EP_INREQUEST) {
+			char *buf;
+			/*
+			 * device: remote wakeup, selfpowered
+			 * interface: nothing
+			 * endpoint: halt
+			 */
+			buf = (char *)urb->transfer_buffer;
+			if (urb->transfer_buffer_length > 0) {
+				if (setup->bRequestType == EP_INREQUEST) {
+					ep2 = vudc_find_endpoint(udc, w_index);
+					if (!ep2) {
+						ret_val = -EOPNOTSUPP;
+						break;
+					}
+					buf[0] = ep2->halted;
+				} else if (setup->bRequestType ==
+					   DEV_INREQUEST) {
+					buf[0] = (u8)udc->devstatus;
+				} else
+					buf[0] = 0;
+			}
+			if (urb->transfer_buffer_length > 1)
+				buf[1] = 0;
+			urb->actual_length = min_t(u32, 2,
+				urb->transfer_buffer_length);
+			ret_val = 0;
+			*status = 0;
+		}
+		break;
+	}
+	return ret_val;
+}
+
+/* Adapted from dummy_hcd.c ; caller must hold lock */
+static int transfer(struct vudc *udc,
+		struct urb *urb, struct vep *ep, int limit)
+{
+	struct vrequest	*req;
+	int sent = 0;
+top:
+	/* if there's no request queued, the device is NAKing; return */
+	list_for_each_entry(req, &ep->req_queue, req_entry) {
+		unsigned int	host_len, dev_len, len;
+		void		*ubuf_pos, *rbuf_pos;
+		int		is_short, to_host;
+		int		rescan = 0;
+
+		/*
+		 * 1..N packets of ep->ep.maxpacket each ... the last one
+		 * may be short (including zero length).
+		 *
+		 * writer can send a zlp explicitly (length 0) or implicitly
+		 * (length mod maxpacket zero, and 'zero' flag); they always
+		 * terminate reads.
+		 */
+		host_len = urb->transfer_buffer_length - urb->actual_length;
+		dev_len = req->req.length - req->req.actual;
+		len = min(host_len, dev_len);
+
+		to_host = usb_pipein(urb->pipe);
+		if (unlikely(len == 0))
+			is_short = 1;
+		else {
+			/* send multiple of maxpacket first, then remainder */
+			if (len >= ep->ep.maxpacket) {
+				is_short = 0;
+				if (len % ep->ep.maxpacket > 0)
+					rescan = 1;
+				len -= len % ep->ep.maxpacket;
+			} else {
+				is_short = 1;
+			}
+
+			ubuf_pos = urb->transfer_buffer + urb->actual_length;
+			rbuf_pos = req->req.buf + req->req.actual;
+
+			if (urb->pipe & USB_DIR_IN)
+				memcpy(ubuf_pos, rbuf_pos, len);
+			else
+				memcpy(rbuf_pos, ubuf_pos, len);
+
+			urb->actual_length += len;
+			req->req.actual += len;
+			sent += len;
+		}
+
+		/*
+		 * short packets terminate, maybe with overflow/underflow.
+		 * it's only really an error to write too much.
+		 *
+		 * partially filling a buffer optionally blocks queue advances
+		 * (so completion handlers can clean up the queue) but we don't
+		 * need to emulate such data-in-flight.
+		 */
+		if (is_short) {
+			if (host_len == dev_len) {
+				req->req.status = 0;
+				urb->status = 0;
+			} else if (to_host) {
+				req->req.status = 0;
+				if (dev_len > host_len)
+					urb->status = -EOVERFLOW;
+				else
+					urb->status = 0;
+			} else {
+				urb->status = 0;
+				if (host_len > dev_len)
+					req->req.status = -EOVERFLOW;
+				else
+					req->req.status = 0;
+			}
+
+		/* many requests terminate without a short packet */
+		/* also check if we need to send zlp */
+		} else {
+			if (req->req.length == req->req.actual) {
+				if (req->req.zero && to_host)
+					rescan = 1;
+				else
+					req->req.status = 0;
+			}
+			if (urb->transfer_buffer_length == urb->actual_length) {
+				if (urb->transfer_flags & URB_ZERO_PACKET &&
+				    !to_host)
+					rescan = 1;
+				else
+					urb->status = 0;
+			}
+		}
+
+		/* device side completion --> continuable */
+		if (req->req.status != -EINPROGRESS) {
+
+			list_del_init(&req->req_entry);
+			spin_unlock(&udc->lock);
+			usb_gadget_giveback_request(&ep->ep, &req->req);
+			spin_lock(&udc->lock);
+
+			/* requests might have been unlinked... */
+			rescan = 1;
+		}
+
+		/* host side completion --> terminate */
+		if (urb->status != -EINPROGRESS)
+			break;
+
+		/* rescan to continue with any other queued i/o */
+		if (rescan)
+			goto top;
+	}
+	return sent;
+}
+
+static void v_timer(struct timer_list *t)
+{
+	struct vudc *udc = from_timer(udc, t, tr_timer.timer);
+	struct transfer_timer *timer = &udc->tr_timer;
+	struct urbp *urb_p, *tmp;
+	unsigned long flags;
+	struct usb_ep *_ep;
+	struct vep *ep;
+	int ret = 0;
+	int total, limit;
+
+	spin_lock_irqsave(&udc->lock, flags);
+
+	total = get_frame_limit(udc->gadget.speed);
+	if (total < 0) {	/* unknown speed, or not set yet */
+		timer->state = VUDC_TR_IDLE;
+		spin_unlock_irqrestore(&udc->lock, flags);
+		return;
+	}
+	/* is it next frame now? */
+	if (time_after(jiffies, timer->frame_start + msecs_to_jiffies(1))) {
+		timer->frame_limit = total;
+		/* FIXME: how to make it accurate? */
+		timer->frame_start = jiffies;
+	} else {
+		total = timer->frame_limit;
+	}
+
+	/* We have to clear ep0 flags separately as it's not on the list */
+	udc->ep[0].already_seen = 0;
+	list_for_each_entry(_ep, &udc->gadget.ep_list, ep_list) {
+		ep = to_vep(_ep);
+		ep->already_seen = 0;
+	}
+
+restart:
+	list_for_each_entry_safe(urb_p, tmp, &udc->urb_queue, urb_entry) {
+		struct urb *urb = urb_p->urb;
+
+		ep = urb_p->ep;
+		if (urb->unlinked)
+			goto return_urb;
+		if (timer->state != VUDC_TR_RUNNING)
+			continue;
+
+		if (!ep) {
+			urb->status = -EPROTO;
+			goto return_urb;
+		}
+
+		/* Used up bandwidth? */
+		if (total <= 0 && ep->type == USB_ENDPOINT_XFER_BULK)
+			continue;
+
+		if (ep->already_seen)
+			continue;
+		ep->already_seen = 1;
+		if (ep == &udc->ep[0] && urb_p->new) {
+			ep->setup_stage = 1;
+			urb_p->new = 0;
+		}
+		if (ep->halted && !ep->setup_stage) {
+			urb->status = -EPIPE;
+			goto return_urb;
+		}
+
+		if (ep == &udc->ep[0] && ep->setup_stage) {
+			/* TODO - flush any stale requests */
+			ep->setup_stage = 0;
+			ep->halted = 0;
+
+			ret = handle_control_request(udc, urb,
+				(struct usb_ctrlrequest *) urb->setup_packet,
+				(&urb->status));
+			if (ret > 0) {
+				spin_unlock(&udc->lock);
+				ret = udc->driver->setup(&udc->gadget,
+					(struct usb_ctrlrequest *)
+					urb->setup_packet);
+				spin_lock(&udc->lock);
+			}
+			if (ret >= 0) {
+				/* no delays (max 64kb data stage) */
+				limit = 64 * 1024;
+				goto treat_control_like_bulk;
+			} else {
+				urb->status = -EPIPE;
+				urb->actual_length = 0;
+				goto return_urb;
+			}
+		}
+
+		limit = total;
+		switch (ep->type) {
+		case USB_ENDPOINT_XFER_ISOC:
+			/* TODO: support */
+			urb->status = -EXDEV;
+			break;
+
+		case USB_ENDPOINT_XFER_INT:
+			/*
+			 * TODO: figure out bandwidth guarantees
+			 * for now, give unlimited bandwidth
+			 */
+			limit += urb->transfer_buffer_length;
+			/* fallthrough */
+		default:
+treat_control_like_bulk:
+			total -= transfer(udc, urb, ep, limit);
+		}
+		if (urb->status == -EINPROGRESS)
+			continue;
+
+return_urb:
+		if (ep)
+			ep->already_seen = ep->setup_stage = 0;
+
+		spin_lock(&udc->lock_tx);
+		list_del(&urb_p->urb_entry);
+		if (!urb->unlinked) {
+			v_enqueue_ret_submit(udc, urb_p);
+		} else {
+			v_enqueue_ret_unlink(udc, urb_p->seqnum,
+					     urb->unlinked);
+			free_urbp_and_urb(urb_p);
+		}
+		wake_up(&udc->tx_waitq);
+		spin_unlock(&udc->lock_tx);
+
+		goto restart;
+	}
+
+	/* TODO - also wait on empty usb_request queues? */
+	if (list_empty(&udc->urb_queue))
+		timer->state = VUDC_TR_IDLE;
+	else
+		mod_timer(&timer->timer,
+			  timer->frame_start + msecs_to_jiffies(1));
+
+	spin_unlock_irqrestore(&udc->lock, flags);
+}
+
+/* All timer functions are run with udc->lock held */
+
+void v_init_timer(struct vudc *udc)
+{
+	struct transfer_timer *t = &udc->tr_timer;
+
+	timer_setup(&t->timer, v_timer, 0);
+	t->state = VUDC_TR_STOPPED;
+}
+
+void v_start_timer(struct vudc *udc)
+{
+	struct transfer_timer *t = &udc->tr_timer;
+
+	dev_dbg(&udc->pdev->dev, "timer start");
+	switch (t->state) {
+	case VUDC_TR_RUNNING:
+		return;
+	case VUDC_TR_IDLE:
+		return v_kick_timer(udc, jiffies);
+	case VUDC_TR_STOPPED:
+		t->state = VUDC_TR_IDLE;
+		t->frame_start = jiffies;
+		t->frame_limit = get_frame_limit(udc->gadget.speed);
+		return v_kick_timer(udc, jiffies);
+	}
+}
+
+void v_kick_timer(struct vudc *udc, unsigned long time)
+{
+	struct transfer_timer *t = &udc->tr_timer;
+
+	dev_dbg(&udc->pdev->dev, "timer kick");
+	switch (t->state) {
+	case VUDC_TR_RUNNING:
+		return;
+	case VUDC_TR_IDLE:
+		t->state = VUDC_TR_RUNNING;
+		/* fallthrough */
+	case VUDC_TR_STOPPED:
+		/* we may want to kick timer to unqueue urbs */
+		mod_timer(&t->timer, time);
+	}
+}
+
+void v_stop_timer(struct vudc *udc)
+{
+	struct transfer_timer *t = &udc->tr_timer;
+
+	/* timer itself will take care of stopping */
+	dev_dbg(&udc->pdev->dev, "timer stop");
+	t->state = VUDC_TR_STOPPED;
+}
diff --git a/drivers/usb/usbip/vudc_tx.c b/drivers/usb/usbip/vudc_tx.c
new file mode 100644
index 000000000..3ccb17c3e
--- /dev/null
+++ b/drivers/usb/usbip/vudc_tx.c
@@ -0,0 +1,284 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (C) 2015 Karol Kosik <karo9@interia.eu>
+ * Copyright (C) 2015-2016 Samsung Electronics
+ *               Igor Kotrasinski <i.kotrasinsk@samsung.com>
+ */
+
+#include <net/sock.h>
+#include <linux/list.h>
+#include <linux/kthread.h>
+
+#include "usbip_common.h"
+#include "vudc.h"
+
+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 urbp *urb_p)
+{
+	setup_base_pdu(&rpdu->base, USBIP_RET_SUBMIT, urb_p->seqnum);
+	usbip_pack_pdu(rpdu, urb_p->urb, USBIP_RET_SUBMIT, 1);
+}
+
+static void setup_ret_unlink_pdu(struct usbip_header *rpdu,
+				 struct v_unlink *unlink)
+{
+	setup_base_pdu(&rpdu->base, USBIP_RET_UNLINK, unlink->seqnum);
+	rpdu->u.ret_unlink.status = unlink->status;
+}
+
+static int v_send_ret_unlink(struct vudc *udc, struct v_unlink *unlink)
+{
+	struct msghdr msg;
+	struct kvec iov[1];
+	size_t txsize;
+
+	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));
+
+	/* 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(udc->ud.tcp_socket, &msg, iov,
+			     1, txsize);
+	if (ret != txsize) {
+		usbip_event_add(&udc->ud, VUDC_EVENT_ERROR_TCP);
+		if (ret >= 0)
+			return -EPIPE;
+		return ret;
+	}
+	kfree(unlink);
+
+	return txsize;
+}
+
+static int v_send_ret_submit(struct vudc *udc, struct urbp *urb_p)
+{
+	struct urb *urb = urb_p->urb;
+	struct usbip_header pdu_header;
+	struct usbip_iso_packet_descriptor *iso_buffer = NULL;
+	struct kvec *iov = NULL;
+	int iovnum = 0;
+	int ret = 0;
+	size_t txsize;
+	struct msghdr msg;
+
+	txsize = 0;
+	memset(&pdu_header, 0, sizeof(pdu_header));
+	memset(&msg, 0, sizeof(msg));
+
+	if (urb->actual_length > 0 && !urb->transfer_buffer) {
+		dev_err(&udc->gadget.dev,
+			"urb: actual_length %d transfer_buffer null\n",
+			urb->actual_length);
+		return -1;
+	}
+
+	if (urb_p->type == USB_ENDPOINT_XFER_ISOC)
+		iovnum = 2 + urb->number_of_packets;
+	else
+		iovnum = 2;
+
+	iov = kcalloc(iovnum, sizeof(*iov), GFP_KERNEL);
+	if (!iov) {
+		usbip_event_add(&udc->ud, VUDC_EVENT_ERROR_MALLOC);
+		ret = -ENOMEM;
+		goto out;
+	}
+	iovnum = 0;
+
+	/* 1. setup usbip_header */
+	setup_ret_submit_pdu(&pdu_header, urb_p);
+	usbip_dbg_stub_tx("setup txdata seqnum: %d\n",
+			  pdu_header.base.seqnum);
+	usbip_header_correct_endian(&pdu_header, 1);
+
+	iov[iovnum].iov_base = &pdu_header;
+	iov[iovnum].iov_len  = sizeof(pdu_header);
+	iovnum++;
+	txsize += sizeof(pdu_header);
+
+	/* 2. setup transfer buffer */
+	if (urb_p->type != USB_ENDPOINT_XFER_ISOC &&
+	    usb_pipein(urb->pipe) && urb->actual_length > 0) {
+		iov[iovnum].iov_base = urb->transfer_buffer;
+		iov[iovnum].iov_len  = urb->actual_length;
+		iovnum++;
+		txsize += urb->actual_length;
+	} else if (urb_p->type == USB_ENDPOINT_XFER_ISOC &&
+		usb_pipein(urb->pipe)) {
+		/* FIXME - copypasted from stub_tx, refactor */
+		int i;
+
+		for (i = 0; i < urb->number_of_packets; i++) {
+			iov[iovnum].iov_base = urb->transfer_buffer +
+				urb->iso_frame_desc[i].offset;
+			iov[iovnum].iov_len =
+				urb->iso_frame_desc[i].actual_length;
+			iovnum++;
+			txsize += urb->iso_frame_desc[i].actual_length;
+		}
+
+		if (txsize != sizeof(pdu_header) + urb->actual_length) {
+			usbip_event_add(&udc->ud, VUDC_EVENT_ERROR_TCP);
+			ret = -EPIPE;
+			goto out;
+		}
+	}
+	/* else - no buffer to send */
+
+	/* 3. setup iso_packet_descriptor */
+	if (urb_p->type == USB_ENDPOINT_XFER_ISOC) {
+		ssize_t len = 0;
+
+		iso_buffer = usbip_alloc_iso_desc_pdu(urb, &len);
+		if (!iso_buffer) {
+			usbip_event_add(&udc->ud,
+					VUDC_EVENT_ERROR_MALLOC);
+			ret = -ENOMEM;
+			goto out;
+		}
+
+		iov[iovnum].iov_base = iso_buffer;
+		iov[iovnum].iov_len  = len;
+		txsize += len;
+		iovnum++;
+	}
+
+	ret = kernel_sendmsg(udc->ud.tcp_socket, &msg,
+						iov,  iovnum, txsize);
+	if (ret != txsize) {
+		usbip_event_add(&udc->ud, VUDC_EVENT_ERROR_TCP);
+		if (ret >= 0)
+			ret = -EPIPE;
+		goto out;
+	}
+
+out:
+	kfree(iov);
+	kfree(iso_buffer);
+	free_urbp_and_urb(urb_p);
+	if (ret < 0)
+		return ret;
+	return txsize;
+}
+
+static int v_send_ret(struct vudc *udc)
+{
+	unsigned long flags;
+	struct tx_item *txi;
+	size_t total_size = 0;
+	int ret = 0;
+
+	spin_lock_irqsave(&udc->lock_tx, flags);
+	while (!list_empty(&udc->tx_queue)) {
+		txi = list_first_entry(&udc->tx_queue, struct tx_item,
+				       tx_entry);
+		list_del(&txi->tx_entry);
+		spin_unlock_irqrestore(&udc->lock_tx, flags);
+
+		switch (txi->type) {
+		case TX_SUBMIT:
+			ret = v_send_ret_submit(udc, txi->s);
+			break;
+		case TX_UNLINK:
+			ret = v_send_ret_unlink(udc, txi->u);
+			break;
+		}
+		kfree(txi);
+
+		if (ret < 0)
+			return ret;
+
+		total_size += ret;
+
+		spin_lock_irqsave(&udc->lock_tx, flags);
+	}
+
+	spin_unlock_irqrestore(&udc->lock_tx, flags);
+	return total_size;
+}
+
+
+int v_tx_loop(void *data)
+{
+	struct usbip_device *ud = (struct usbip_device *) data;
+	struct vudc *udc = container_of(ud, struct vudc, ud);
+	int ret;
+
+	while (!kthread_should_stop()) {
+		if (usbip_event_happened(&udc->ud))
+			break;
+		ret = v_send_ret(udc);
+		if (ret < 0) {
+			pr_warn("v_tx exit with error %d", ret);
+			break;
+		}
+		wait_event_interruptible(udc->tx_waitq,
+					 (!list_empty(&udc->tx_queue) ||
+					 kthread_should_stop()));
+	}
+
+	return 0;
+}
+
+/* called with spinlocks held */
+void v_enqueue_ret_unlink(struct vudc *udc, __u32 seqnum, __u32 status)
+{
+	struct tx_item *txi;
+	struct v_unlink *unlink;
+
+	txi = kzalloc(sizeof(*txi), GFP_ATOMIC);
+	if (!txi) {
+		usbip_event_add(&udc->ud, VDEV_EVENT_ERROR_MALLOC);
+		return;
+	}
+	unlink = kzalloc(sizeof(*unlink), GFP_ATOMIC);
+	if (!unlink) {
+		kfree(txi);
+		usbip_event_add(&udc->ud, VDEV_EVENT_ERROR_MALLOC);
+		return;
+	}
+
+	unlink->seqnum = seqnum;
+	unlink->status = status;
+	txi->type = TX_UNLINK;
+	txi->u = unlink;
+
+	list_add_tail(&txi->tx_entry, &udc->tx_queue);
+}
+
+/* called with spinlocks held */
+void v_enqueue_ret_submit(struct vudc *udc, struct urbp *urb_p)
+{
+	struct tx_item *txi;
+
+	txi = kzalloc(sizeof(*txi), GFP_ATOMIC);
+	if (!txi) {
+		usbip_event_add(&udc->ud, VDEV_EVENT_ERROR_MALLOC);
+		return;
+	}
+
+	txi->type = TX_SUBMIT;
+	txi->s = urb_p;
+
+	list_add_tail(&txi->tx_entry, &udc->tx_queue);
+}