usbip: move usbip kernel code out of staging

At this point, USB/IP kernel code is fully functional
and can be moved out of staging.

Signed-off-by: Valentina Manea <valentina.manea.m@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 1171 insertions, 0 deletions

diff --git a/drivers/usb/usbip/vhci_hcd.c b/drivers/usb/usbip/vhci_hcd.c
new file mode 100644
index 000000000000..c02374b6049c
--- /dev/null
+++ b/drivers/usb/usbip/vhci_hcd.c
@@ -0,0 +1,1171 @@
+/*
+ * Copyright (C) 2003-2008 Takahiro Hirofuchi
+ *
+ * This is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307,
+ * USA.
+ */
+
+#include <linux/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";
+
+struct vhci_hcd *the_controller;
+
+static const char * const bit_desc[] = {
+	"CONNECTION",		/*0*/
+	"ENABLE",		/*1*/
+	"SUSPEND",		/*2*/
+	"OVER_CURRENT",		/*3*/
+	"RESET",		/*4*/
+	"R5",			/*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*/
+	"R21",			/*21*/
+	"R22",			/*22*/
+	"R23",			/*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)
+{
+	int i = 0;
+	u32 bit = 1;
+
+	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, bit_desc[i]);
+		bit <<= 1;
+		i++;
+	}
+	pr_debug("\n");
+}
+
+void rh_port_connect(int rhport, enum usb_device_speed speed)
+{
+	usbip_dbg_vhci_rh("rh_port_connect %d\n", rhport);
+
+	spin_lock(&the_controller->lock);
+
+	the_controller->port_status[rhport] |= USB_PORT_STAT_CONNECTION
+		| (1 << USB_PORT_FEAT_C_CONNECTION);
+
+	switch (speed) {
+	case USB_SPEED_HIGH:
+		the_controller->port_status[rhport] |= USB_PORT_STAT_HIGH_SPEED;
+		break;
+	case USB_SPEED_LOW:
+		the_controller->port_status[rhport] |= USB_PORT_STAT_LOW_SPEED;
+		break;
+	default:
+		break;
+	}
+
+	spin_unlock(&the_controller->lock);
+
+	usb_hcd_poll_rh_status(vhci_to_hcd(the_controller));
+}
+
+static void rh_port_disconnect(int rhport)
+{
+	usbip_dbg_vhci_rh("rh_port_disconnect %d\n", rhport);
+
+	spin_lock(&the_controller->lock);
+
+	the_controller->port_status[rhport] &= ~USB_PORT_STAT_CONNECTION;
+	the_controller->port_status[rhport] |=
+					(1 << USB_PORT_FEAT_C_CONNECTION);
+
+	spin_unlock(&the_controller->lock);
+	usb_hcd_poll_rh_status(vhci_to_hcd(the_controller));
+}
+
+#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;
+	int		retval;
+	int		rhport;
+	int		changed = 0;
+
+	retval = DIV_ROUND_UP(VHCI_NPORTS + 1, 8);
+	memset(buf, 0, retval);
+
+	vhci = hcd_to_vhci(hcd);
+
+	spin_lock(&vhci->lock);
+	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_NPORTS; rhport++) {
+		if ((vhci->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(&vhci->lock);
+	return changed ? retval : 0;
+}
+
+static inline void hub_descriptor(struct usb_hub_descriptor *desc)
+{
+	memset(desc, 0, sizeof(*desc));
+	desc->bDescriptorType = 0x29;
+	desc->bDescLength = 9;
+	desc->wHubCharacteristics = (__constant_cpu_to_le16(0x0001));
+	desc->bNbrPorts = VHCI_NPORTS;
+	desc->u.hs.DeviceRemovable[0] = 0xff;
+	desc->u.hs.DeviceRemovable[1] = 0xff;
+}
+
+static int vhci_hub_control(struct usb_hcd *hcd, u16 typeReq, u16 wValue,
+			    u16 wIndex, char *buf, u16 wLength)
+{
+	struct vhci_hcd	*dum;
+	int             retval = 0;
+	int		rhport;
+
+	u32 prev_port_status[VHCI_NPORTS];
+
+	if (!HCD_HW_ACCESSIBLE(hcd))
+		return -ETIMEDOUT;
+
+	/*
+	 * NOTE:
+	 * wIndex shows the port number and begins from 1.
+	 */
+	usbip_dbg_vhci_rh("typeReq %x wValue %x wIndex %x\n", typeReq, wValue,
+			  wIndex);
+	if (wIndex > VHCI_NPORTS)
+		pr_err("invalid port number %d\n", wIndex);
+	rhport = ((__u8)(wIndex & 0x00ff)) - 1;
+
+	dum = hcd_to_vhci(hcd);
+
+	spin_lock(&dum->lock);
+
+	/* store old status and compare now and old later */
+	if (usbip_dbg_flag_vhci_rh) {
+		memcpy(prev_port_status, dum->port_status,
+			sizeof(prev_port_status));
+	}
+
+	switch (typeReq) {
+	case ClearHubFeature:
+		usbip_dbg_vhci_rh(" ClearHubFeature\n");
+		break;
+	case ClearPortFeature:
+		switch (wValue) {
+		case USB_PORT_FEAT_SUSPEND:
+			if (dum->port_status[rhport] & USB_PORT_STAT_SUSPEND) {
+				/* 20msec signaling */
+				dum->resuming = 1;
+				dum->re_timeout =
+					jiffies + msecs_to_jiffies(20);
+			}
+			break;
+		case USB_PORT_FEAT_POWER:
+			usbip_dbg_vhci_rh(
+				" ClearPortFeature: USB_PORT_FEAT_POWER\n");
+			dum->port_status[rhport] = 0;
+			dum->resuming = 0;
+			break;
+		case USB_PORT_FEAT_C_RESET:
+			usbip_dbg_vhci_rh(
+				" ClearPortFeature: USB_PORT_FEAT_C_RESET\n");
+			switch (dum->vdev[rhport].speed) {
+			case USB_SPEED_HIGH:
+				dum->port_status[rhport] |=
+					USB_PORT_STAT_HIGH_SPEED;
+				break;
+			case USB_SPEED_LOW:
+				dum->port_status[rhport] |=
+					USB_PORT_STAT_LOW_SPEED;
+				break;
+			default:
+				break;
+			}
+		default:
+			usbip_dbg_vhci_rh(" ClearPortFeature: default %x\n",
+					  wValue);
+			dum->port_status[rhport] &= ~(1 << wValue);
+			break;
+		}
+		break;
+	case GetHubDescriptor:
+		usbip_dbg_vhci_rh(" GetHubDescriptor\n");
+		hub_descriptor((struct usb_hub_descriptor *) buf);
+		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 (wIndex > VHCI_NPORTS || wIndex < 1) {
+			pr_err("invalid port number %d\n", wIndex);
+			retval = -EPIPE;
+		}
+
+		/* we do not care about resume. */
+
+		/* whoever resets or resumes must GetPortStatus to
+		 * complete it!!
+		 */
+		if (dum->resuming && time_after(jiffies, dum->re_timeout)) {
+			dum->port_status[rhport] |=
+				(1 << USB_PORT_FEAT_C_SUSPEND);
+			dum->port_status[rhport] &=
+				~(1 << USB_PORT_FEAT_SUSPEND);
+			dum->resuming = 0;
+			dum->re_timeout = 0;
+		}
+
+		if ((dum->port_status[rhport] & (1 << USB_PORT_FEAT_RESET)) !=
+		    0 && time_after(jiffies, dum->re_timeout)) {
+			dum->port_status[rhport] |=
+				(1 << USB_PORT_FEAT_C_RESET);
+			dum->port_status[rhport] &=
+				~(1 << USB_PORT_FEAT_RESET);
+			dum->re_timeout = 0;
+
+			if (dum->vdev[rhport].ud.status ==
+			    VDEV_ST_NOTASSIGNED) {
+				usbip_dbg_vhci_rh(
+					" enable rhport %d (status %u)\n",
+					rhport,
+					dum->vdev[rhport].ud.status);
+				dum->port_status[rhport] |=
+					USB_PORT_STAT_ENABLE;
+			}
+		}
+		((__le16 *) buf)[0] = cpu_to_le16(dum->port_status[rhport]);
+		((__le16 *) buf)[1] =
+			cpu_to_le16(dum->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_SUSPEND:
+			usbip_dbg_vhci_rh(
+				" SetPortFeature: USB_PORT_FEAT_SUSPEND\n");
+			break;
+		case USB_PORT_FEAT_RESET:
+			usbip_dbg_vhci_rh(
+				" SetPortFeature: USB_PORT_FEAT_RESET\n");
+			/* if it's already running, disconnect first */
+			if (dum->port_status[rhport] & USB_PORT_STAT_ENABLE) {
+				dum->port_status[rhport] &=
+					~(USB_PORT_STAT_ENABLE |
+					  USB_PORT_STAT_LOW_SPEED |
+					  USB_PORT_STAT_HIGH_SPEED);
+				/* FIXME test that code path! */
+			}
+			/* 50msec reset signaling */
+			dum->re_timeout = jiffies + msecs_to_jiffies(50);
+
+			/* FALLTHROUGH */
+		default:
+			usbip_dbg_vhci_rh(" SetPortFeature: default %d\n",
+					  wValue);
+			dum->port_status[rhport] |= (1 << wValue);
+			break;
+		}
+		break;
+
+	default:
+		pr_err("default: no such request\n");
+
+		/* "protocol stall" on error */
+		retval = -EPIPE;
+	}
+
+	if (usbip_dbg_flag_vhci_rh) {
+		pr_debug("port %d\n", rhport);
+		/* Only dump valid port status */
+		if (rhport >= 0) {
+			dump_port_status_diff(prev_port_status[rhport],
+					      dum->port_status[rhport]);
+		}
+	}
+	usbip_dbg_vhci_rh(" bye\n");
+
+	spin_unlock(&dum->lock);
+
+	return retval;
+}
+
+static struct vhci_device *get_vdev(struct usb_device *udev)
+{
+	int i;
+
+	if (!udev)
+		return NULL;
+
+	for (i = 0; i < VHCI_NPORTS; i++)
+		if (the_controller->vdev[i].udev == udev)
+			return port_to_vdev(i);
+
+	return NULL;
+}
+
+static void vhci_tx_urb(struct urb *urb)
+{
+	struct vhci_device *vdev = get_vdev(urb->dev);
+	struct vhci_priv *priv;
+
+	if (!vdev) {
+		pr_err("could not get virtual device");
+		return;
+	}
+
+	priv = kzalloc(sizeof(struct vhci_priv), GFP_ATOMIC);
+	if (!priv) {
+		usbip_event_add(&vdev->ud, VDEV_EVENT_ERROR_MALLOC);
+		return;
+	}
+
+	spin_lock(&vdev->priv_lock);
+
+	priv->seqnum = atomic_inc_return(&the_controller->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(&vdev->priv_lock);
+}
+
+static int vhci_urb_enqueue(struct usb_hcd *hcd, struct urb *urb,
+			    gfp_t mem_flags)
+{
+	struct device *dev = &urb->dev->dev;
+	int ret = 0;
+	struct vhci_device *vdev;
+
+	usbip_dbg_vhci_hc("enter, usb_hcd %p urb %p mem_flags %d\n",
+			  hcd, urb, mem_flags);
+
+	/* patch to usb_sg_init() is in 2.5.60 */
+	BUG_ON(!urb->transfer_buffer && urb->transfer_buffer_length);
+
+	spin_lock(&the_controller->lock);
+
+	if (urb->status != -EINPROGRESS) {
+		dev_err(dev, "URB already unlinked!, status %d\n", urb->status);
+		spin_unlock(&the_controller->lock);
+		return urb->status;
+	}
+
+	vdev = port_to_vdev(urb->dev->portnum-1);
+
+	/* 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(&the_controller->lock);
+		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);
+
+			if (vdev->udev)
+				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");
+
+			if (vdev->udev)
+				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);
+	spin_unlock(&the_controller->lock);
+
+	return 0;
+
+no_need_xmit:
+	usb_hcd_unlink_urb_from_ep(hcd, urb);
+no_need_unlink:
+	spin_unlock(&the_controller->lock);
+	usb_hcd_giveback_urb(vhci_to_hcd(the_controller), 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_priv *priv;
+	struct vhci_device *vdev;
+
+	pr_info("dequeue a urb %p\n", urb);
+
+	spin_lock(&the_controller->lock);
+
+	priv = urb->hcpriv;
+	if (!priv) {
+		/* URB was never linked! or will be soon given back by
+		 * vhci_rx. */
+		spin_unlock(&the_controller->lock);
+		return 0;
+	}
+
+	{
+		int ret = 0;
+
+		ret = usb_hcd_check_unlink_urb(hcd, urb, status);
+		if (ret) {
+			spin_unlock(&the_controller->lock);
+			return ret;
+		}
+	}
+
+	 /* send unlink request here? */
+	vdev = priv->vdev;
+
+	if (!vdev->ud.tcp_socket) {
+		/* tcp connection is closed */
+		spin_lock(&vdev->priv_lock);
+
+		pr_info("device %p seems to be disconnected\n", vdev);
+		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.
+		 */
+		pr_info("gives back urb %p\n", urb);
+
+		usb_hcd_unlink_urb_from_ep(hcd, urb);
+
+		spin_unlock(&the_controller->lock);
+		usb_hcd_giveback_urb(vhci_to_hcd(the_controller), urb,
+				     urb->status);
+		spin_lock(&the_controller->lock);
+
+	} 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(&the_controller->lock);
+			usbip_event_add(&vdev->ud, VDEV_EVENT_ERROR_MALLOC);
+			return -ENOMEM;
+		}
+
+		unlink->seqnum = atomic_inc_return(&the_controller->seqnum);
+		if (unlink->seqnum == 0xffff)
+			pr_info("seqnum max\n");
+
+		unlink->unlink_seqnum = priv->seqnum;
+
+		pr_info("device %p seems to be still connected\n", vdev);
+
+		/* 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(&the_controller->lock);
+
+	usbip_dbg_vhci_hc("leave\n");
+	return 0;
+}
+
+static void vhci_device_unlink_cleanup(struct vhci_device *vdev)
+{
+	struct vhci_unlink *unlink, *tmp;
+
+	spin_lock(&the_controller->lock);
+	spin_lock(&vdev->priv_lock);
+
+	list_for_each_entry_safe(unlink, tmp, &vdev->unlink_tx, list) {
+		pr_info("unlink cleanup tx %lu\n", unlink->unlink_seqnum);
+		list_del(&unlink->list);
+		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(vhci_to_hcd(the_controller), urb);
+
+		list_del(&unlink->list);
+
+		spin_unlock(&vdev->priv_lock);
+		spin_unlock(&the_controller->lock);
+
+		usb_hcd_giveback_urb(vhci_to_hcd(the_controller), urb,
+				     urb->status);
+
+		spin_lock(&the_controller->lock);
+		spin_lock(&vdev->priv_lock);
+
+		kfree(unlink);
+	}
+
+	spin_unlock(&vdev->priv_lock);
+	spin_unlock(&the_controller->lock);
+}
+
+/*
+ * 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 %p\n", ud->tcp_socket);
+		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;
+	}
+	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->rhport);
+
+	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);
+
+	spin_lock(&ud->lock);
+
+	vdev->speed  = 0;
+	vdev->devid  = 0;
+
+	if (vdev->udev)
+		usb_put_dev(vdev->udev);
+	vdev->udev = NULL;
+
+	if (ud->tcp_socket) {
+		sockfd_put(ud->tcp_socket);
+		ud->tcp_socket = NULL;
+	}
+	ud->status = VDEV_ST_NULL;
+
+	spin_unlock(&ud->lock);
+}
+
+static void vhci_device_unusable(struct usbip_device *ud)
+{
+	spin_lock(&ud->lock);
+	ud->status = VDEV_ST_ERROR;
+	spin_unlock(&ud->lock);
+}
+
+static void vhci_device_init(struct vhci_device *vdev)
+{
+	memset(vdev, 0, sizeof(*vdev));
+
+	vdev->ud.side   = USBIP_VHCI;
+	vdev->ud.status = VDEV_ST_NULL;
+	spin_lock_init(&vdev->ud.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 vhci_start(struct usb_hcd *hcd)
+{
+	struct vhci_hcd *vhci = hcd_to_vhci(hcd);
+	int rhport;
+	int err = 0;
+
+	usbip_dbg_vhci_hc("enter vhci_start\n");
+
+	/* initialize private data of usb_hcd */
+
+	for (rhport = 0; rhport < VHCI_NPORTS; rhport++) {
+		struct vhci_device *vdev = &vhci->vdev[rhport];
+
+		vhci_device_init(vdev);
+		vdev->rhport = rhport;
+	}
+
+	atomic_set(&vhci->seqnum, 0);
+	spin_lock_init(&vhci->lock);
+
+	hcd->power_budget = 0; /* no limit */
+	hcd->uses_new_polling = 1;
+
+	/* vhci_hcd is now ready to be controlled through sysfs */
+	err = sysfs_create_group(&vhci_dev(vhci)->kobj, &dev_attr_group);
+	if (err) {
+		pr_err("create sysfs files\n");
+		return err;
+	}
+
+	return 0;
+}
+
+static void vhci_stop(struct usb_hcd *hcd)
+{
+	struct vhci_hcd *vhci = hcd_to_vhci(hcd);
+	int rhport = 0;
+
+	usbip_dbg_vhci_hc("stop VHCI controller\n");
+
+	/* 1. remove the userland interface of vhci_hcd */
+	sysfs_remove_group(&vhci_dev(vhci)->kobj, &dev_attr_group);
+
+	/* 2. shutdown all the ports of vhci_hcd */
+	for (rhport = 0; rhport < VHCI_NPORTS; rhport++) {
+		struct vhci_device *vdev = &vhci->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)
+{
+	pr_err("Not yet implemented\n");
+	return 0;
+}
+
+#ifdef CONFIG_PM
+
+/* FIXME: suspend/resume */
+static int vhci_bus_suspend(struct usb_hcd *hcd)
+{
+	struct vhci_hcd *vhci = hcd_to_vhci(hcd);
+
+	dev_dbg(&hcd->self.root_hub->dev, "%s\n", __func__);
+
+	spin_lock(&vhci->lock);
+	hcd->state = HC_STATE_SUSPENDED;
+	spin_unlock(&vhci->lock);
+
+	return 0;
+}
+
+static int vhci_bus_resume(struct usb_hcd *hcd)
+{
+	struct vhci_hcd *vhci = hcd_to_vhci(hcd);
+	int rc = 0;
+
+	dev_dbg(&hcd->self.root_hub->dev, "%s\n", __func__);
+
+	spin_lock(&vhci->lock);
+	if (!HCD_HW_ACCESSIBLE(hcd))
+		rc = -ESHUTDOWN;
+	else
+		hcd->state = HC_STATE_RUNNING;
+	spin_unlock(&vhci->lock);
+
+	return rc;
+}
+
+#else
+
+#define vhci_bus_suspend      NULL
+#define vhci_bus_resume       NULL
+#endif
+
+static struct hc_driver vhci_hc_driver = {
+	.description	= driver_name,
+	.product_desc	= driver_desc,
+	.hcd_priv_size	= sizeof(struct vhci_hcd),
+
+	.flags		= HCD_USB2,
+
+	.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,
+};
+
+static int vhci_hcd_probe(struct platform_device *pdev)
+{
+	struct usb_hcd		*hcd;
+	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 = usb_create_hcd(&vhci_hc_driver, &pdev->dev, dev_name(&pdev->dev));
+	if (!hcd) {
+		pr_err("create hcd failed\n");
+		return -ENOMEM;
+	}
+	hcd->has_tt = 1;
+
+	/* this is private data for vhci_hcd */
+	the_controller = hcd_to_vhci(hcd);
+
+	/*
+	 * Finish generic HCD structure initialization and register.
+	 * Call the driver's reset() and start() routines.
+	 */
+	ret = usb_add_hcd(hcd, 0, 0);
+	if (ret != 0) {
+		pr_err("usb_add_hcd failed %d\n", ret);
+		usb_put_hcd(hcd);
+		the_controller = NULL;
+		return ret;
+	}
+
+	usbip_dbg_vhci_hc("bye\n");
+	return 0;
+}
+
+static int vhci_hcd_remove(struct platform_device *pdev)
+{
+	struct usb_hcd	*hcd;
+
+	hcd = platform_get_drvdata(pdev);
+	if (!hcd)
+		return 0;
+
+	/*
+	 * Disconnects the root hub,
+	 * then reverses the effects of usb_add_hcd(),
+	 * invoking the HCD's stop() methods.
+	 */
+	usb_remove_hcd(hcd);
+	usb_put_hcd(hcd);
+	the_controller = 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;
+	int rhport = 0;
+	int connected = 0;
+	int ret = 0;
+
+	hcd = platform_get_drvdata(pdev);
+
+	spin_lock(&the_controller->lock);
+
+	for (rhport = 0; rhport < VHCI_NPORTS; rhport++)
+		if (the_controller->port_status[rhport] &
+		    USB_PORT_STAT_CONNECTION)
+			connected += 1;
+
+	spin_unlock(&the_controller->lock);
+
+	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);
+	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,
+		.owner = THIS_MODULE,
+	},
+};
+
+/*
+ * The VHCI 'device' is 'virtual'; not a real plug&play hardware.
+ * We need to add this virtual device as a platform device arbitrarily:
+ *	1. platform_device_register()
+ */
+static void the_pdev_release(struct device *dev)
+{
+}
+
+static struct platform_device the_pdev = {
+	/* should be the same name as driver_name */
+	.name = driver_name,
+	.id = -1,
+	.dev = {
+		.release = the_pdev_release,
+	},
+};
+
+static int __init vhci_hcd_init(void)
+{
+	int ret;
+
+	if (usb_disabled())
+		return -ENODEV;
+
+	ret = platform_driver_register(&vhci_driver);
+	if (ret)
+		goto err_driver_register;
+
+	ret = platform_device_register(&the_pdev);
+	if (ret)
+		goto err_platform_device_register;
+
+	pr_info(DRIVER_DESC " v" USBIP_VERSION "\n");
+	return ret;
+
+err_platform_device_register:
+	platform_driver_unregister(&vhci_driver);
+err_driver_register:
+	return ret;
+}
+
+static void __exit vhci_hcd_exit(void)
+{
+	platform_device_unregister(&the_pdev);
+	platform_driver_unregister(&vhci_driver);
+}
+
+module_init(vhci_hcd_init);
+module_exit(vhci_hcd_exit);
+
+MODULE_AUTHOR(DRIVER_AUTHOR);
+MODULE_DESCRIPTION(DRIVER_DESC);
+MODULE_LICENSE("GPL");
+MODULE_VERSION(USBIP_VERSION);