drivers/staging/usbip/stub_rx.c - kernel/skids - Git at Google

 /*
  * Copyright (C) 2003-2008 Takahiro Hirofuchi
  *
  * This is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
  * the Free Software Foundation; either version 2 of the License, or
  * (at your option) any later version.
  *
  * This is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  * GNU General Public License for more details.
  *
  * You should have received a copy of the GNU General Public License
  * along with this program; if not, write to the Free Software
  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307,
  * USA.
  */

 #include <linux/slab.h>

 #include "usbip_common.h"
 #include "stub.h"
 #include <linux/usb/hcd.h>


 static int is_clear_halt_cmd(struct urb *urb)
 {
 	struct usb_ctrlrequest *req;

 	req = (struct usb_ctrlrequest *) urb->setup_packet;

 	 return (req->bRequest == USB_REQ_CLEAR_FEATURE) &&
 		 (req->bRequestType == USB_RECIP_ENDPOINT) &&
 		 (req->wValue == USB_ENDPOINT_HALT);
 }

 static int is_set_interface_cmd(struct urb *urb)
 {
 	struct usb_ctrlrequest *req;

 	req = (struct usb_ctrlrequest *) urb->setup_packet;

 	return (req->bRequest == USB_REQ_SET_INTERFACE) &&
 		   (req->bRequestType == USB_RECIP_INTERFACE);
 }

 static int is_set_configuration_cmd(struct urb *urb)
 {
 	struct usb_ctrlrequest *req;

 	req = (struct usb_ctrlrequest *) urb->setup_packet;

 	return (req->bRequest == USB_REQ_SET_CONFIGURATION) &&
 		   (req->bRequestType == USB_RECIP_DEVICE);
 }

 static int is_reset_device_cmd(struct urb *urb)
 {
 	struct usb_ctrlrequest *req;
 	__u16 value;
 	__u16 index;

 	req = (struct usb_ctrlrequest *) urb->setup_packet;
 	value = le16_to_cpu(req->wValue);
 	index = le16_to_cpu(req->wIndex);

 	if ((req->bRequest == USB_REQ_SET_FEATURE) &&
 			(req->bRequestType == USB_RT_PORT) &&
 			(value == USB_PORT_FEAT_RESET)) {
 		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)
 		usbip_uinfo("clear_halt error: devnum %d endp %d, %d\n",
 					urb->dev->devnum, target_endp, ret);
 	else
 		usbip_uinfo("clear_halt done: devnum %d endp %d\n",
 					urb->dev->devnum, target_endp);

 	return ret;
 }

 static int tweak_set_interface_cmd(struct urb *urb)
 {
 	struct usb_ctrlrequest *req;
 	__u16 alternate;
 	__u16 interface;
 	int ret;

 	req = (struct usb_ctrlrequest *) urb->setup_packet;
 	alternate = le16_to_cpu(req->wValue);
 	interface = le16_to_cpu(req->wIndex);

 	usbip_dbg_stub_rx("set_interface: inf %u alt %u\n", interface,
 								alternate);

 	ret = usb_set_interface(urb->dev, interface, alternate);
 	if (ret < 0)
 		usbip_uinfo("set_interface error: inf %u alt %u, %d\n",
 					interface, alternate, ret);
 	else
 		usbip_uinfo("set_interface done: inf %u alt %u\n",
 							interface,
 							alternate);

 	return ret;
 }

 static int tweak_set_configuration_cmd(struct urb *urb)
 {
 	struct usb_ctrlrequest *req;
 	__u16 config;

 	req = (struct usb_ctrlrequest *) urb->setup_packet;
 	config = le16_to_cpu(req->wValue);

 	/*
 	 * I have never seen a multi-config device. Very rare.
 	 * For most devices, this will be called to choose a default
 	 * configuration only once in an initialization phase.
 	 *
 	 * set_configuration may change a device configuration and its device
 	 * drivers will be unbound and assigned for a new device configuration.
 	 * This means this usbip driver will be also unbound when called, then
 	 * eventually reassigned to the device as far as driver matching
 	 * condition is kept.
 	 *
 	 * Unfortunatelly, an existing usbip connection will be dropped
 	 * due to this driver unbinding. So, skip here.
 	 * A user may need to set a special configuration value before
 	 * exporting the device.
 	 */
 	usbip_uinfo("set_configuration (%d) to %s\n", config,
 						dev_name(&urb->dev->dev));
 	usbip_uinfo("but, skip!\n");

 	return 0;
 	/* return usb_driver_set_configuration(urb->dev, config); */
 }

 static int tweak_reset_device_cmd(struct urb *urb)
 {
 	struct usb_ctrlrequest *req;
 	__u16 value;
 	__u16 index;
 	int ret;

 	req = (struct usb_ctrlrequest *) urb->setup_packet;
 	value = le16_to_cpu(req->wValue);
 	index = le16_to_cpu(req->wIndex);

 	usbip_uinfo("reset_device (port %d) to %s\n", index,
 						dev_name(&urb->dev->dev));

 	/* all interfaces should be owned by usbip driver, so just reset it.  */
 	ret = usb_lock_device_for_reset(urb->dev, NULL);
 	if (ret < 0) {
 		dev_err(&urb->dev->dev, "lock for reset\n");
 		return ret;
 	}

 	/* try to reset the device */
 	ret = usb_reset_device(urb->dev);
 	if (ret < 0)
 		dev_err(&urb->dev->dev, "device reset\n");

 	usb_unlock_device(urb->dev);

 	return ret;
 }

 /*
  * clear_halt, set_interface, and set_configuration require special tricks.
  */
 static void tweak_special_requests(struct urb *urb)
 {
 	if (!urb || !urb->setup_packet)
 		return;

 	if (usb_pipetype(urb->pipe) != PIPE_CONTROL)
 		return;

 	if (is_clear_halt_cmd(urb))
 		/* tweak clear_halt */
 		 tweak_clear_halt_cmd(urb);

 	else if (is_set_interface_cmd(urb))
 		/* tweak set_interface */
 		tweak_set_interface_cmd(urb);

 	else if (is_set_configuration_cmd(urb))
 		/* tweak set_configuration */
 		tweak_set_configuration_cmd(urb);

 	else if (is_reset_device_cmd(urb))
 		tweak_reset_device_cmd(urb);
 	else
 		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)
 {
 	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) {
 			int ret;

 			dev_info(&priv->urb->dev->dev, "unlink urb %p\n",
 				 priv->urb);

 			/*
 			 * This matched urb is not completed yet (i.e., be in
 			 * flight in usb hcd hardware/driver). Now we are
 			 * cancelling it. The unlinking flag means that we are
 			 * now not going to return the normal result pdu of a
 			 * submission request, but going to return a result pdu
 			 * of the unlink request.
 			 */
 			priv->unlinking = 1;

 			/*
 			 * In the case that unlinking flag is on, prev->seqnum
 			 * is changed from the seqnum of the cancelling urb to
 			 * the seqnum of the unlink request. This will be used
 			 * to make the result pdu of the unlink request.
 			 */
 			priv->seqnum = pdu->base.seqnum;

 			spin_unlock_irqrestore(&sdev->priv_lock, flags);

 			/*
 			 * usb_unlink_urb() is now out of spinlocking to avoid
 			 * spinlock recursion since stub_complete() is
 			 * sometimes called in this context but not in the
 			 * interrupt context.  If stub_complete() is executed
 			 * before we call usb_unlink_urb(), usb_unlink_urb()
 			 * will return an error value. In this case, stub_tx
 			 * will return the result pdu of this unlink request
 			 * though submission is completed and actual unlinking
 			 * is not executed. OK?
 			 */
 			/* In the above case, urb->status is not -ECONNRESET,
 			 * so a driver in a client host will know the failure
 			 * of the unlink request ?
 			 */
 			ret = usb_unlink_urb(priv->urb);
 			if (ret != -EINPROGRESS)
 				dev_err(&priv->urb->dev->dev,
 					"failed to unlink a urb %p, ret %d\n",
 					priv->urb, ret);
 			return 0;
 		}
 	}

 	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;

 	if (pdu->base.devid == sdev->devid) {
 		spin_lock(&ud->lock);
 		if (ud->status == SDEV_ST_USED) {
 			/* A request is valid. */
 			spin_unlock(&ud->lock);
 			return 1;
 		}
 		spin_unlock(&ud->lock);
 	}

 	return 0;
 }

 static struct stub_priv *stub_priv_alloc(struct stub_device *sdev,
 					 struct usbip_header *pdu)
 {
 	struct stub_priv *priv;
 	struct usbip_device *ud = &sdev->ud;
 	unsigned long flags;

 	spin_lock_irqsave(&sdev->priv_lock, flags);

 	priv = kmem_cache_zalloc(stub_priv_cache, GFP_ATOMIC);
 	if (!priv) {
 		dev_err(&sdev->interface->dev, "alloc stub_priv\n");
 		spin_unlock_irqrestore(&sdev->priv_lock, flags);
 		usbip_event_add(ud, SDEV_EVENT_ERROR_MALLOC);
 		return NULL;
 	}

 	priv->seqnum = pdu->base.seqnum;
 	priv->sdev = sdev;

 	/*
 	 * After a stub_priv is linked to a list_head,
 	 * our error handler can free allocated data.
 	 */
 	list_add_tail(&priv->list, &sdev->priv_init);

 	spin_unlock_irqrestore(&sdev->priv_lock, flags);

 	return priv;
 }


 static struct usb_host_endpoint *get_ep_from_epnum(struct usb_device *udev,
 		int epnum0)
 {
 	struct usb_host_config *config;
 	int i = 0, j = 0;
 	struct usb_host_endpoint *ep = NULL;
 	int epnum;
 	int found = 0;

 	if (epnum0 == 0)
 		return &udev->ep0;

 	config = udev->actconfig;
 	if (!config)
 		return NULL;

 	for (i = 0; i < config->desc.bNumInterfaces; i++) {
 		struct usb_host_interface *setting;

 		setting = config->interface[i]->cur_altsetting;

 		for (j = 0; j < setting->desc.bNumEndpoints; j++) {
 			ep = &setting->endpoint[j];
 			epnum = (ep->desc.bEndpointAddress & 0x7f);

 			if (epnum == epnum0) {
 				/* usbip_uinfo("found epnum %d\n", epnum0);*/
 				found = 1;
 				break;
 			}
 		}
 	}

 	if (found)
 		return ep;
 	else
 		return NULL;
 }


 static int get_pipe(struct stub_device *sdev, int epnum, int dir)
 {
 	struct usb_device *udev = interface_to_usbdev(sdev->interface);
 	struct usb_host_endpoint *ep;
 	struct usb_endpoint_descriptor *epd = NULL;

 	ep = get_ep_from_epnum(udev, epnum);
 	if (!ep) {
 		dev_err(&sdev->interface->dev, "no such endpoint?, %d\n",
 			epnum);
 		BUG();
 	}

 	epd = &ep->desc;


 #if 0
 	/* epnum 0 is always control */
 	if (epnum == 0) {
 		if (dir == USBIP_DIR_OUT)
 			return usb_sndctrlpipe(udev, 0);
 		else
 			return usb_rcvctrlpipe(udev, 0);
 	}
 #endif

 	if (usb_endpoint_xfer_control(epd)) {
 		if (dir == USBIP_DIR_OUT)
 			return usb_sndctrlpipe(udev, epnum);
 		else
 			return usb_rcvctrlpipe(udev, epnum);
 	}

 	if (usb_endpoint_xfer_bulk(epd)) {
 		if (dir == USBIP_DIR_OUT)
 			return usb_sndbulkpipe(udev, epnum);
 		else
 			return usb_rcvbulkpipe(udev, epnum);
 	}

 	if (usb_endpoint_xfer_int(epd)) {
 		if (dir == USBIP_DIR_OUT)
 			return usb_sndintpipe(udev, epnum);
 		else
 			return usb_rcvintpipe(udev, epnum);
 	}

 	if (usb_endpoint_xfer_isoc(epd)) {
 		if (dir == USBIP_DIR_OUT)
 			return usb_sndisocpipe(udev, epnum);
 		else
 			return usb_rcvisocpipe(udev, epnum);
 	}

 	/* NOT REACHED */
 	dev_err(&sdev->interface->dev, "get pipe, epnum %d\n", epnum);
 	return 0;
 }

 static void stub_recv_cmd_submit(struct stub_device *sdev,
 				 struct usbip_header *pdu)
 {
 	int ret;
 	struct stub_priv *priv;
 	struct usbip_device *ud = &sdev->ud;
 	struct usb_device *udev = interface_to_usbdev(sdev->interface);
 	int pipe = get_pipe(sdev, pdu->base.ep, pdu->base.direction);


 	priv = stub_priv_alloc(sdev, pdu);
 	if (!priv)
 		return;

 	/* setup a urb */
 	if (usb_pipeisoc(pipe))
 		priv->urb = usb_alloc_urb(pdu->u.cmd_submit.number_of_packets,
 								GFP_KERNEL);
 	else
 		priv->urb = usb_alloc_urb(0, GFP_KERNEL);

 	if (!priv->urb) {
 		dev_err(&sdev->interface->dev, "malloc urb\n");
 		usbip_event_add(ud, SDEV_EVENT_ERROR_MALLOC);
 		return;
 	}

 	/* set priv->urb->transfer_buffer */
 	if (pdu->u.cmd_submit.transfer_buffer_length > 0) {
 		priv->urb->transfer_buffer =
 			kzalloc(pdu->u.cmd_submit.transfer_buffer_length,
 								GFP_KERNEL);
 		if (!priv->urb->transfer_buffer) {
 			dev_err(&sdev->interface->dev, "malloc x_buff\n");
 			usbip_event_add(ud, SDEV_EVENT_ERROR_MALLOC);
 			return;
 		}
 	}

 	/* set priv->urb->setup_packet */
 	priv->urb->setup_packet = kmemdup(&pdu->u.cmd_submit.setup, 8,
 					  GFP_KERNEL);
 	if (!priv->urb->setup_packet) {
 		dev_err(&sdev->interface->dev, "allocate setup_packet\n");
 		usbip_event_add(ud, SDEV_EVENT_ERROR_MALLOC);
 		return;
 	}

 	/* set other members from the base header of pdu */
 	priv->urb->context                = (void *) priv;
 	priv->urb->dev                    = udev;
 	priv->urb->pipe                   = pipe;
 	priv->urb->complete               = stub_complete;

 	usbip_pack_pdu(pdu, priv->urb, USBIP_CMD_SUBMIT, 0);


 	if (usbip_recv_xbuff(ud, priv->urb) < 0)
 		return;

 	if (usbip_recv_iso(ud, priv->urb) < 0)
 		return;

 	/* no need to submit an intercepted request, but harmless? */
 	tweak_special_requests(priv->urb);

 	/* urb is now ready to submit */
 	ret = usb_submit_urb(priv->urb, GFP_KERNEL);

 	if (ret == 0)
 		usbip_dbg_stub_rx("submit urb ok, seqnum %u\n",
 							pdu->base.seqnum);
 	else {
 		dev_err(&sdev->interface->dev, "submit_urb error, %d\n", ret);
 		usbip_dump_header(pdu);
 		usbip_dump_urb(priv->urb);

 		/*
 		 * Pessimistic.
 		 * This connection will be discarded.
 		 */
 		usbip_event_add(ud, SDEV_EVENT_ERROR_SUBMIT);
 	}

 	usbip_dbg_stub_rx("Leave\n");
 	return;
 }

 /* recv a pdu */
 static void stub_rx_pdu(struct usbip_device *ud)
 {
 	int ret;
 	struct usbip_header pdu;
 	struct stub_device *sdev = container_of(ud, struct stub_device, ud);
 	struct device *dev = &sdev->interface->dev;

 	usbip_dbg_stub_rx("Enter\n");

 	memset(&pdu, 0, sizeof(pdu));

 	/* 1. receive a pdu header */
 	ret = usbip_xmit(0, ud->tcp_socket, (char *) &pdu, sizeof(pdu), 0);
 	if (ret != sizeof(pdu)) {
 		dev_err(dev, "recv a header, %d\n", ret);
 		usbip_event_add(ud, SDEV_EVENT_ERROR_TCP);
 		return;
 	}

 	usbip_header_correct_endian(&pdu, 0);

 	if (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);
 		return;
 	}

 }

 void stub_rx_loop(struct usbip_task *ut)
 {
 	struct usbip_device *ud = container_of(ut, struct usbip_device, tcp_rx);

 	while (1) {
 		if (signal_pending(current)) {
 			usbip_dbg_stub_rx("signal caught!\n");
 			break;
 		}

 		if (usbip_event_happened(ud))
 			break;

 		stub_rx_pdu(ud);
 	}
 }
	/*
	* 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/slab.h>

	#include "usbip_common.h"
	#include "stub.h"
	#include <linux/usb/hcd.h>


	static int is_clear_halt_cmd(struct urb *urb)
	{
	struct usb_ctrlrequest *req;

	req = (struct usb_ctrlrequest *) urb->setup_packet;

	return (req->bRequest == USB_REQ_CLEAR_FEATURE) &&
	(req->bRequestType == USB_RECIP_ENDPOINT) &&
	(req->wValue == USB_ENDPOINT_HALT);
	}

	static int is_set_interface_cmd(struct urb *urb)
	{
	struct usb_ctrlrequest *req;

	req = (struct usb_ctrlrequest *) urb->setup_packet;

	return (req->bRequest == USB_REQ_SET_INTERFACE) &&
	(req->bRequestType == USB_RECIP_INTERFACE);
	}

	static int is_set_configuration_cmd(struct urb *urb)
	{
	struct usb_ctrlrequest *req;

	req = (struct usb_ctrlrequest *) urb->setup_packet;

	return (req->bRequest == USB_REQ_SET_CONFIGURATION) &&
	(req->bRequestType == USB_RECIP_DEVICE);
	}

	static int is_reset_device_cmd(struct urb *urb)
	{
	struct usb_ctrlrequest *req;
	__u16 value;
	__u16 index;

	req = (struct usb_ctrlrequest *) urb->setup_packet;
	value = le16_to_cpu(req->wValue);
	index = le16_to_cpu(req->wIndex);

	if ((req->bRequest == USB_REQ_SET_FEATURE) &&
	(req->bRequestType == USB_RT_PORT) &&
	(value == USB_PORT_FEAT_RESET)) {
	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)
	usbip_uinfo("clear_halt error: devnum %d endp %d, %d\n",
	urb->dev->devnum, target_endp, ret);
	else
	usbip_uinfo("clear_halt done: devnum %d endp %d\n",
	urb->dev->devnum, target_endp);

	return ret;
	}

	static int tweak_set_interface_cmd(struct urb *urb)
	{
	struct usb_ctrlrequest *req;
	__u16 alternate;
	__u16 interface;
	int ret;

	req = (struct usb_ctrlrequest *) urb->setup_packet;
	alternate = le16_to_cpu(req->wValue);
	interface = le16_to_cpu(req->wIndex);

	usbip_dbg_stub_rx("set_interface: inf %u alt %u\n", interface,
	alternate);

	ret = usb_set_interface(urb->dev, interface, alternate);
	if (ret < 0)
	usbip_uinfo("set_interface error: inf %u alt %u, %d\n",
	interface, alternate, ret);
	else
	usbip_uinfo("set_interface done: inf %u alt %u\n",
	interface,
	alternate);

	return ret;
	}

	static int tweak_set_configuration_cmd(struct urb *urb)
	{
	struct usb_ctrlrequest *req;
	__u16 config;

	req = (struct usb_ctrlrequest *) urb->setup_packet;
	config = le16_to_cpu(req->wValue);

	/*
	* I have never seen a multi-config device. Very rare.
	* For most devices, this will be called to choose a default
	* configuration only once in an initialization phase.
	*
	* set_configuration may change a device configuration and its device
	* drivers will be unbound and assigned for a new device configuration.
	* This means this usbip driver will be also unbound when called, then
	* eventually reassigned to the device as far as driver matching
	* condition is kept.
	*
	* Unfortunatelly, an existing usbip connection will be dropped
	* due to this driver unbinding. So, skip here.
	* A user may need to set a special configuration value before
	* exporting the device.
	*/
	usbip_uinfo("set_configuration (%d) to %s\n", config,
	dev_name(&urb->dev->dev));
	usbip_uinfo("but, skip!\n");

	return 0;
	/* return usb_driver_set_configuration(urb->dev, config); */
	}

	static int tweak_reset_device_cmd(struct urb *urb)
	{
	struct usb_ctrlrequest *req;
	__u16 value;
	__u16 index;
	int ret;

	req = (struct usb_ctrlrequest *) urb->setup_packet;
	value = le16_to_cpu(req->wValue);
	index = le16_to_cpu(req->wIndex);

	usbip_uinfo("reset_device (port %d) to %s\n", index,
	dev_name(&urb->dev->dev));

	/* all interfaces should be owned by usbip driver, so just reset it. */
	ret = usb_lock_device_for_reset(urb->dev, NULL);
	if (ret < 0) {
	dev_err(&urb->dev->dev, "lock for reset\n");
	return ret;
	}

	/* try to reset the device */
	ret = usb_reset_device(urb->dev);
	if (ret < 0)
	dev_err(&urb->dev->dev, "device reset\n");

	usb_unlock_device(urb->dev);

	return ret;
	}

	/*
	* clear_halt, set_interface, and set_configuration require special tricks.
	*/
	static void tweak_special_requests(struct urb *urb)
	{
	if (!urb \|\| !urb->setup_packet)
	return;

	if (usb_pipetype(urb->pipe) != PIPE_CONTROL)
	return;

	if (is_clear_halt_cmd(urb))
	/* tweak clear_halt */
	tweak_clear_halt_cmd(urb);

	else if (is_set_interface_cmd(urb))
	/* tweak set_interface */
	tweak_set_interface_cmd(urb);

	else if (is_set_configuration_cmd(urb))
	/* tweak set_configuration */
	tweak_set_configuration_cmd(urb);

	else if (is_reset_device_cmd(urb))
	tweak_reset_device_cmd(urb);
	else
	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)
	{
	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) {
	int ret;

	dev_info(&priv->urb->dev->dev, "unlink urb %p\n",
	priv->urb);

	/*
	* This matched urb is not completed yet (i.e., be in
	* flight in usb hcd hardware/driver). Now we are
	* cancelling it. The unlinking flag means that we are
	* now not going to return the normal result pdu of a
	* submission request, but going to return a result pdu
	* of the unlink request.
	*/
	priv->unlinking = 1;

	/*
	* In the case that unlinking flag is on, prev->seqnum
	* is changed from the seqnum of the cancelling urb to
	* the seqnum of the unlink request. This will be used
	* to make the result pdu of the unlink request.
	*/
	priv->seqnum = pdu->base.seqnum;

	spin_unlock_irqrestore(&sdev->priv_lock, flags);

	/*
	* usb_unlink_urb() is now out of spinlocking to avoid
	* spinlock recursion since stub_complete() is
	* sometimes called in this context but not in the
	* interrupt context. If stub_complete() is executed
	* before we call usb_unlink_urb(), usb_unlink_urb()
	* will return an error value. In this case, stub_tx
	* will return the result pdu of this unlink request
	* though submission is completed and actual unlinking
	* is not executed. OK?
	*/
	/* In the above case, urb->status is not -ECONNRESET,
	* so a driver in a client host will know the failure
	* of the unlink request ?
	*/
	ret = usb_unlink_urb(priv->urb);
	if (ret != -EINPROGRESS)
	dev_err(&priv->urb->dev->dev,
	"failed to unlink a urb %p, ret %d\n",
	priv->urb, ret);
	return 0;
	}
	}

	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;

	if (pdu->base.devid == sdev->devid) {
	spin_lock(&ud->lock);
	if (ud->status == SDEV_ST_USED) {
	/* A request is valid. */
	spin_unlock(&ud->lock);
	return 1;
	}
	spin_unlock(&ud->lock);
	}

	return 0;
	}

	static struct stub_priv stub_priv_alloc(struct stub_device sdev,
	struct usbip_header *pdu)
	{
	struct stub_priv *priv;
	struct usbip_device *ud = &sdev->ud;
	unsigned long flags;

	spin_lock_irqsave(&sdev->priv_lock, flags);

	priv = kmem_cache_zalloc(stub_priv_cache, GFP_ATOMIC);
	if (!priv) {
	dev_err(&sdev->interface->dev, "alloc stub_priv\n");
	spin_unlock_irqrestore(&sdev->priv_lock, flags);
	usbip_event_add(ud, SDEV_EVENT_ERROR_MALLOC);
	return NULL;
	}

	priv->seqnum = pdu->base.seqnum;
	priv->sdev = sdev;

	/*
	* After a stub_priv is linked to a list_head,
	* our error handler can free allocated data.
	*/
	list_add_tail(&priv->list, &sdev->priv_init);

	spin_unlock_irqrestore(&sdev->priv_lock, flags);

	return priv;
	}


	static struct usb_host_endpoint get_ep_from_epnum(struct usb_device udev,
	int epnum0)
	{
	struct usb_host_config *config;
	int i = 0, j = 0;
	struct usb_host_endpoint *ep = NULL;
	int epnum;
	int found = 0;

	if (epnum0 == 0)
	return &udev->ep0;

	config = udev->actconfig;
	if (!config)
	return NULL;

	for (i = 0; i < config->desc.bNumInterfaces; i++) {
	struct usb_host_interface *setting;

	setting = config->interface[i]->cur_altsetting;

	for (j = 0; j < setting->desc.bNumEndpoints; j++) {
	ep = &setting->endpoint[j];
	epnum = (ep->desc.bEndpointAddress & 0x7f);

	if (epnum == epnum0) {
	/* usbip_uinfo("found epnum %d\n", epnum0);*/
	found = 1;
	break;
	}
	}
	}

	if (found)
	return ep;
	else
	return NULL;
	}


	static int get_pipe(struct stub_device *sdev, int epnum, int dir)
	{
	struct usb_device *udev = interface_to_usbdev(sdev->interface);
	struct usb_host_endpoint *ep;
	struct usb_endpoint_descriptor *epd = NULL;

	ep = get_ep_from_epnum(udev, epnum);
	if (!ep) {
	dev_err(&sdev->interface->dev, "no such endpoint?, %d\n",
	epnum);
	BUG();
	}

	epd = &ep->desc;


	#if 0
	/* epnum 0 is always control */
	if (epnum == 0) {
	if (dir == USBIP_DIR_OUT)
	return usb_sndctrlpipe(udev, 0);
	else
	return usb_rcvctrlpipe(udev, 0);
	}
	#endif

	if (usb_endpoint_xfer_control(epd)) {
	if (dir == USBIP_DIR_OUT)
	return usb_sndctrlpipe(udev, epnum);
	else
	return usb_rcvctrlpipe(udev, epnum);
	}

	if (usb_endpoint_xfer_bulk(epd)) {
	if (dir == USBIP_DIR_OUT)
	return usb_sndbulkpipe(udev, epnum);
	else
	return usb_rcvbulkpipe(udev, epnum);
	}

	if (usb_endpoint_xfer_int(epd)) {
	if (dir == USBIP_DIR_OUT)
	return usb_sndintpipe(udev, epnum);
	else
	return usb_rcvintpipe(udev, epnum);
	}

	if (usb_endpoint_xfer_isoc(epd)) {
	if (dir == USBIP_DIR_OUT)
	return usb_sndisocpipe(udev, epnum);
	else
	return usb_rcvisocpipe(udev, epnum);
	}

	/* NOT REACHED */
	dev_err(&sdev->interface->dev, "get pipe, epnum %d\n", epnum);
	return 0;
	}

	static void stub_recv_cmd_submit(struct stub_device *sdev,
	struct usbip_header *pdu)
	{
	int ret;
	struct stub_priv *priv;
	struct usbip_device *ud = &sdev->ud;
	struct usb_device *udev = interface_to_usbdev(sdev->interface);
	int pipe = get_pipe(sdev, pdu->base.ep, pdu->base.direction);


	priv = stub_priv_alloc(sdev, pdu);
	if (!priv)
	return;

	/* setup a urb */
	if (usb_pipeisoc(pipe))
	priv->urb = usb_alloc_urb(pdu->u.cmd_submit.number_of_packets,
	GFP_KERNEL);
	else
	priv->urb = usb_alloc_urb(0, GFP_KERNEL);

	if (!priv->urb) {
	dev_err(&sdev->interface->dev, "malloc urb\n");
	usbip_event_add(ud, SDEV_EVENT_ERROR_MALLOC);
	return;
	}

	/* set priv->urb->transfer_buffer */
	if (pdu->u.cmd_submit.transfer_buffer_length > 0) {
	priv->urb->transfer_buffer =
	kzalloc(pdu->u.cmd_submit.transfer_buffer_length,
	GFP_KERNEL);
	if (!priv->urb->transfer_buffer) {
	dev_err(&sdev->interface->dev, "malloc x_buff\n");
	usbip_event_add(ud, SDEV_EVENT_ERROR_MALLOC);
	return;
	}
	}

	/* set priv->urb->setup_packet */
	priv->urb->setup_packet = kmemdup(&pdu->u.cmd_submit.setup, 8,
	GFP_KERNEL);
	if (!priv->urb->setup_packet) {
	dev_err(&sdev->interface->dev, "allocate setup_packet\n");
	usbip_event_add(ud, SDEV_EVENT_ERROR_MALLOC);
	return;
	}

	/* set other members from the base header of pdu */
	priv->urb->context = (void *) priv;
	priv->urb->dev = udev;
	priv->urb->pipe = pipe;
	priv->urb->complete = stub_complete;

	usbip_pack_pdu(pdu, priv->urb, USBIP_CMD_SUBMIT, 0);


	if (usbip_recv_xbuff(ud, priv->urb) < 0)
	return;

	if (usbip_recv_iso(ud, priv->urb) < 0)
	return;

	/* no need to submit an intercepted request, but harmless? */
	tweak_special_requests(priv->urb);

	/* urb is now ready to submit */
	ret = usb_submit_urb(priv->urb, GFP_KERNEL);

	if (ret == 0)
	usbip_dbg_stub_rx("submit urb ok, seqnum %u\n",
	pdu->base.seqnum);
	else {
	dev_err(&sdev->interface->dev, "submit_urb error, %d\n", ret);
	usbip_dump_header(pdu);
	usbip_dump_urb(priv->urb);

	/*
	* Pessimistic.
	* This connection will be discarded.
	*/
	usbip_event_add(ud, SDEV_EVENT_ERROR_SUBMIT);
	}

	usbip_dbg_stub_rx("Leave\n");
	return;
	}

	/* recv a pdu */
	static void stub_rx_pdu(struct usbip_device *ud)
	{
	int ret;
	struct usbip_header pdu;
	struct stub_device *sdev = container_of(ud, struct stub_device, ud);
	struct device *dev = &sdev->interface->dev;

	usbip_dbg_stub_rx("Enter\n");

	memset(&pdu, 0, sizeof(pdu));

	/* 1. receive a pdu header */
	ret = usbip_xmit(0, ud->tcp_socket, (char *) &pdu, sizeof(pdu), 0);
	if (ret != sizeof(pdu)) {
	dev_err(dev, "recv a header, %d\n", ret);
	usbip_event_add(ud, SDEV_EVENT_ERROR_TCP);
	return;
	}

	usbip_header_correct_endian(&pdu, 0);

	if (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);
	return;
	}

	}

	void stub_rx_loop(struct usbip_task *ut)
	{
	struct usbip_device *ud = container_of(ut, struct usbip_device, tcp_rx);

	while (1) {
	if (signal_pending(current)) {
	usbip_dbg_stub_rx("signal caught!\n");
	break;
	}

	if (usbip_event_happened(ud))
	break;

	stub_rx_pdu(ud);
	}
	}