/*
   * USB Network driver infrastructure
   * Copyright (C) 2000-2005 by David Brownell
   * Copyright (C) 2003-2005 David Hollis <dhollis@davehollis.com>
   *
   * This program 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 program 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, see <http://www.gnu.org/licenses/>.
   */
  
  /*
   * This is a generic "USB networking" framework that works with several
   * kinds of full and high speed networking devices:  host-to-host cables,
   * smart usb peripherals, and actual Ethernet adapters.
   *
   * These devices usually differ in terms of control protocols (if they
   * even have one!) and sometimes they define new framing to wrap or batch
   * Ethernet packets.  Otherwise, they talk to USB pretty much the same,
   * so interface (un)binding, endpoint I/O queues, fault handling, and other
   * issues can usefully be addressed by this framework.
   */
  
  // #define	DEBUG			// error path messages, extra info
  // #define	VERBOSE			// more; success messages
  
  #include <linux/module.h>
  #include <linux/init.h>
  #include <linux/netdevice.h>
  #include <linux/etherdevice.h>
  #include <linux/ctype.h>
  #include <linux/ethtool.h>
  #include <linux/workqueue.h>
  #include <linux/mii.h>
  #include <linux/usb.h>
  #include <linux/usb/usbnet.h>
  #include <linux/usb/cdc.h>
  #include <linux/slab.h>
  #include <linux/kernel.h>
  #include <linux/pm_runtime.h>
  
  #define DRIVER_VERSION		"22-Aug-2005"
  
  
  /*-------------------------------------------------------------------------*/
  
  /*
   * Nineteen USB 1.1 max size bulk transactions per frame (ms), max.
   * Several dozen bytes of IPv4 data can fit in two such transactions.
   * One maximum size Ethernet packet takes twenty four of them.
   * For high speed, each frame comfortably fits almost 36 max size
   * Ethernet packets (so queues should be bigger).
   *
   * The goal is to let the USB host controller be busy for 5msec or
   * more before an irq is required, under load.  Jumbograms change
   * the equation.
   */
  #define	MAX_QUEUE_MEMORY	(60 * 1518)
  #define	RX_QLEN(dev)		((dev)->rx_qlen)
  #define	TX_QLEN(dev)		((dev)->tx_qlen)
  
  // reawaken network queue this soon after stopping; else watchdog barks
  #define TX_TIMEOUT_JIFFIES	(5*HZ)
  
  /* throttle rx/tx briefly after some faults, so hub_wq might disconnect()
   * us (it polls at HZ/4 usually) before we report too many false errors.
   */
  #define THROTTLE_JIFFIES	(HZ/8)
  
  // between wakeups
  #define UNLINK_TIMEOUT_MS	3
  
  /*-------------------------------------------------------------------------*/
  
  // randomly generated ethernet address
  static u8	node_id [ETH_ALEN];
  
  static const char driver_name [] = "usbnet";
  
  /* use ethtool to change the level for any given device */
  static int msg_level = -1;
  module_param (msg_level, int, 0);
  MODULE_PARM_DESC (msg_level, "Override default message level");
  
  /*-------------------------------------------------------------------------*/
  
  /* handles CDC Ethernet and many other network "bulk data" interfaces */
  int usbnet_get_endpoints(struct usbnet *dev, struct usb_interface *intf)
  {
  	int				tmp;
  	struct usb_host_interface	*alt = NULL;
  	struct usb_host_endpoint	*in = NULL, *out = NULL;
  	struct usb_host_endpoint	*status = NULL;
  
  	for (tmp = 0; tmp < intf->num_altsetting; tmp++) {
  		unsigned	ep;
  
  		in = out = status = NULL;
  		alt = intf->altsetting + tmp;
  
  		/* take the first altsetting with in-bulk + out-bulk;
  		 * remember any status endpoint, just in case;
  		 * ignore other endpoints and altsettings.
  		 */
  		for (ep = 0; ep < alt->desc.bNumEndpoints; ep++) {
  			struct usb_host_endpoint	*e;
  			int				intr = 0;
  
  			e = alt->endpoint + ep;
  			switch (e->desc.bmAttributes) {
  			case USB_ENDPOINT_XFER_INT:
  				if (!usb_endpoint_dir_in(&e->desc))
  					continue;
  				intr = 1;
  				/* FALLTHROUGH */
  			case USB_ENDPOINT_XFER_BULK:
  				break;
  			default:
  				continue;
  			}
  			if (usb_endpoint_dir_in(&e->desc)) {
  				if (!intr && !in)
  					in = e;
  				else if (intr && !status)
  					status = e;
  			} else {
  				if (!out)
  					out = e;
  			}
  		}
  		if (in && out)
  			break;
  	}
  	if (!alt || !in || !out)
  		return -EINVAL;
  
  	if (alt->desc.bAlternateSetting != 0 ||
  	    !(dev->driver_info->flags & FLAG_NO_SETINT)) {
  		tmp = usb_set_interface (dev->udev, alt->desc.bInterfaceNumber,
  				alt->desc.bAlternateSetting);
  		if (tmp < 0)
  			return tmp;
  	}
  
  	dev->in = usb_rcvbulkpipe (dev->udev,
  			in->desc.bEndpointAddress & USB_ENDPOINT_NUMBER_MASK);
  	dev->out = usb_sndbulkpipe (dev->udev,
  			out->desc.bEndpointAddress & USB_ENDPOINT_NUMBER_MASK);
  	dev->status = status;
  	return 0;
  }
  EXPORT_SYMBOL_GPL(usbnet_get_endpoints);
  
  int usbnet_get_ethernet_addr(struct usbnet *dev, int iMACAddress)
  {
  	int 		tmp = -1, ret;
  	unsigned char	buf [13];
  
  	ret = usb_string(dev->udev, iMACAddress, buf, sizeof buf);
  	if (ret == 12)
  		tmp = hex2bin(dev->net->dev_addr, buf, 6);
  	if (tmp < 0) {
  		dev_dbg(&dev->udev->dev,
  			"bad MAC string %d fetch, %d
  ", iMACAddress, tmp);
  		if (ret >= 0)
  			ret = -EINVAL;
  		return ret;
  	}
  	return 0;
  }
  EXPORT_SYMBOL_GPL(usbnet_get_ethernet_addr);
  
  static void intr_complete (struct urb *urb)
  {
  	struct usbnet	*dev = urb->context;
  	int		status = urb->status;
  
  	switch (status) {
  	/* success */
  	case 0:
  		dev->driver_info->status(dev, urb);
  		break;
  
  	/* software-driven interface shutdown */
  	case -ENOENT:		/* urb killed */
  	case -ESHUTDOWN:	/* hardware gone */
  		netif_dbg(dev, ifdown, dev->net,
  			  "intr shutdown, code %d
  ", status);
  		return;
  
  	/* NOTE:  not throttling like RX/TX, since this endpoint
  	 * already polls infrequently
  	 */
  	default:
  		netdev_dbg(dev->net, "intr status %d
  ", status);
  		break;
  	}
  
  	status = usb_submit_urb (urb, GFP_ATOMIC);
  	if (status != 0)
  		netif_err(dev, timer, dev->net,
  			  "intr resubmit --> %d
  ", status);
  }
  
  static int init_status (struct usbnet *dev, struct usb_interface *intf)
  {
  	char		*buf = NULL;
  	unsigned	pipe = 0;
  	unsigned	maxp;
  	unsigned	period;
  
  	if (!dev->driver_info->status)
  		return 0;
  
  	pipe = usb_rcvintpipe (dev->udev,
  			dev->status->desc.bEndpointAddress
  				& USB_ENDPOINT_NUMBER_MASK);
  	maxp = usb_maxpacket (dev->udev, pipe, 0);
  
  	/* avoid 1 msec chatter:  min 8 msec poll rate */
  	period = max ((int) dev->status->desc.bInterval,
  		(dev->udev->speed == USB_SPEED_HIGH) ? 7 : 3);
  
  	buf = kmalloc (maxp, GFP_KERNEL);
  	if (buf) {
  		dev->interrupt = usb_alloc_urb (0, GFP_KERNEL);
  		if (!dev->interrupt) {
  			kfree (buf);
  			return -ENOMEM;
  		} else {
  			usb_fill_int_urb(dev->interrupt, dev->udev, pipe,
  				buf, maxp, intr_complete, dev, period);
  			dev->interrupt->transfer_flags |= URB_FREE_BUFFER;
  			dev_dbg(&intf->dev,
  				"status ep%din, %d bytes period %d
  ",
  				usb_pipeendpoint(pipe), maxp, period);
  		}
  	}
  	return 0;
  }
  
  /* Submit the interrupt URB if not previously submitted, increasing refcount */
  int usbnet_status_start(struct usbnet *dev, gfp_t mem_flags)
  {
  	int ret = 0;
  
  	WARN_ON_ONCE(dev->interrupt == NULL);
  	if (dev->interrupt) {
  		mutex_lock(&dev->interrupt_mutex);
  
  		if (++dev->interrupt_count == 1)
  			ret = usb_submit_urb(dev->interrupt, mem_flags);
  
  		dev_dbg(&dev->udev->dev, "incremented interrupt URB count to %d
  ",
  			dev->interrupt_count);
  		mutex_unlock(&dev->interrupt_mutex);
  	}
  	return ret;
  }
  EXPORT_SYMBOL_GPL(usbnet_status_start);
  
  /* For resume; submit interrupt URB if previously submitted */
  static int __usbnet_status_start_force(struct usbnet *dev, gfp_t mem_flags)
  {
  	int ret = 0;
  
  	mutex_lock(&dev->interrupt_mutex);
  	if (dev->interrupt_count) {
  		ret = usb_submit_urb(dev->interrupt, mem_flags);
  		dev_dbg(&dev->udev->dev,
  			"submitted interrupt URB for resume
  ");
  	}
  	mutex_unlock(&dev->interrupt_mutex);
  	return ret;
  }
  
  /* Kill the interrupt URB if all submitters want it killed */
  void usbnet_status_stop(struct usbnet *dev)
  {
  	if (dev->interrupt) {
  		mutex_lock(&dev->interrupt_mutex);
  		WARN_ON(dev->interrupt_count == 0);
  
  		if (dev->interrupt_count && --dev->interrupt_count == 0)
  			usb_kill_urb(dev->interrupt);
  
  		dev_dbg(&dev->udev->dev,
  			"decremented interrupt URB count to %d
  ",
  			dev->interrupt_count);
  		mutex_unlock(&dev->interrupt_mutex);
  	}
  }
  EXPORT_SYMBOL_GPL(usbnet_status_stop);
  
  /* For suspend; always kill interrupt URB */
  static void __usbnet_status_stop_force(struct usbnet *dev)
  {
  	if (dev->interrupt) {
  		mutex_lock(&dev->interrupt_mutex);
  		usb_kill_urb(dev->interrupt);
  		dev_dbg(&dev->udev->dev, "killed interrupt URB for suspend
  ");
  		mutex_unlock(&dev->interrupt_mutex);
  	}
  }
  
  /* Passes this packet up the stack, updating its accounting.
   * Some link protocols batch packets, so their rx_fixup paths
   * can return clones as well as just modify the original skb.
   */
  void usbnet_skb_return (struct usbnet *dev, struct sk_buff *skb)
  {
  	int	status;
  
  	if (test_bit(EVENT_RX_PAUSED, &dev->flags)) {
  		skb_queue_tail(&dev->rxq_pause, skb);
  		return;
  	}
  
  	skb->protocol = eth_type_trans (skb, dev->net);
  	dev->net->stats.rx_packets++;
  	dev->net->stats.rx_bytes += skb->len;
  
  	netif_dbg(dev, rx_status, dev->net, "< rx, len %zu, type 0x%x
  ",
  		  skb->len + sizeof (struct ethhdr), skb->protocol);
  	memset (skb->cb, 0, sizeof (struct skb_data));
  
  	if (skb_defer_rx_timestamp(skb))
  		return;
  
  	status = netif_rx (skb);
  	if (status != NET_RX_SUCCESS)
  		netif_dbg(dev, rx_err, dev->net,
  			  "netif_rx status %d
  ", status);
  }
  EXPORT_SYMBOL_GPL(usbnet_skb_return);
  
  /* must be called if hard_mtu or rx_urb_size changed */
  void usbnet_update_max_qlen(struct usbnet *dev)
  {
  	enum usb_device_speed speed = dev->udev->speed;
  
  	switch (speed) {
  	case USB_SPEED_HIGH:
  		dev->rx_qlen = MAX_QUEUE_MEMORY / dev->rx_urb_size;
  		dev->tx_qlen = MAX_QUEUE_MEMORY / dev->hard_mtu;
  		break;
  	case USB_SPEED_SUPER:
  		/*
  		 * Not take default 5ms qlen for super speed HC to
  		 * save memory, and iperf tests show 2.5ms qlen can
  		 * work well
  		 */
  		dev->rx_qlen = 5 * MAX_QUEUE_MEMORY / dev->rx_urb_size;
  		dev->tx_qlen = 5 * MAX_QUEUE_MEMORY / dev->hard_mtu;
  		break;
  	default:
  		dev->rx_qlen = dev->tx_qlen = 4;
  	}
  }
  EXPORT_SYMBOL_GPL(usbnet_update_max_qlen);
  
  
  /*-------------------------------------------------------------------------
   *
   * Network Device Driver (peer link to "Host Device", from USB host)
   *
   *-------------------------------------------------------------------------*/
  
  int usbnet_change_mtu (struct net_device *net, int new_mtu)
  {
  	struct usbnet	*dev = netdev_priv(net);
  	int		ll_mtu = new_mtu + net->hard_header_len;
  	int		old_hard_mtu = dev->hard_mtu;
  	int		old_rx_urb_size = dev->rx_urb_size;
  
  	if (new_mtu <= 0)
  		return -EINVAL;
  	// no second zero-length packet read wanted after mtu-sized packets
  	if ((ll_mtu % dev->maxpacket) == 0)
  		return -EDOM;
  	net->mtu = new_mtu;
  
  	dev->hard_mtu = net->mtu + net->hard_header_len;
  	if (dev->rx_urb_size == old_hard_mtu) {
  		dev->rx_urb_size = dev->hard_mtu;
  		if (dev->rx_urb_size > old_rx_urb_size)
  			usbnet_unlink_rx_urbs(dev);
  	}
  
  	/* max qlen depend on hard_mtu and rx_urb_size */
  	usbnet_update_max_qlen(dev);
  
  	return 0;
  }
  EXPORT_SYMBOL_GPL(usbnet_change_mtu);
  
  /* The caller must hold list->lock */
  static void __usbnet_queue_skb(struct sk_buff_head *list,
  			struct sk_buff *newsk, enum skb_state state)
  {
  	struct skb_data *entry = (struct skb_data *) newsk->cb;
  
  	__skb_queue_tail(list, newsk);
  	entry->state = state;
  }
  
  /*-------------------------------------------------------------------------*/
  
  /* some LK 2.4 HCDs oopsed if we freed or resubmitted urbs from
   * completion callbacks.  2.5 should have fixed those bugs...
   */
  
  static enum skb_state defer_bh(struct usbnet *dev, struct sk_buff *skb,
  		struct sk_buff_head *list, enum skb_state state)
  {
  	unsigned long		flags;
  	enum skb_state 		old_state;
  	struct skb_data *entry = (struct skb_data *) skb->cb;
  
  	spin_lock_irqsave(&list->lock, flags);
  	old_state = entry->state;
  	entry->state = state;
  	__skb_unlink(skb, list);
  
  	/* defer_bh() is never called with list == &dev->done.
  	 * spin_lock_nested() tells lockdep that it is OK to take
  	 * dev->done.lock here with list->lock held.
  	 */
  	spin_lock_nested(&dev->done.lock, SINGLE_DEPTH_NESTING);
  
  	__skb_queue_tail(&dev->done, skb);
  	if (dev->done.qlen == 1)
  		tasklet_schedule(&dev->bh);
  	spin_unlock(&dev->done.lock);
  	spin_unlock_irqrestore(&list->lock, flags);
  	return old_state;
  }
  
  /* some work can't be done in tasklets, so we use keventd
   *
   * NOTE:  annoying asymmetry:  if it's active, schedule_work() fails,
   * but tasklet_schedule() doesn't.  hope the failure is rare.
   */
  void usbnet_defer_kevent (struct usbnet *dev, int work)
  {
  	set_bit (work, &dev->flags);
  	if (!schedule_work (&dev->kevent)) {
  		if (net_ratelimit())
  			netdev_err(dev->net, "kevent %d may have been dropped
  ", work);
  	} else {
  		netdev_dbg(dev->net, "kevent %d scheduled
  ", work);
  	}
  }
  EXPORT_SYMBOL_GPL(usbnet_defer_kevent);
  
  /*-------------------------------------------------------------------------*/
  
  static void rx_complete (struct urb *urb);
  
  static int rx_submit (struct usbnet *dev, struct urb *urb, gfp_t flags)
  {
  	struct sk_buff		*skb;
  	struct skb_data		*entry;
  	int			retval = 0;
  	unsigned long		lockflags;
  	size_t			size = dev->rx_urb_size;
  
  	/* prevent rx skb allocation when error ratio is high */
  	if (test_bit(EVENT_RX_KILL, &dev->flags)) {
  		usb_free_urb(urb);
  		return -ENOLINK;
  	}
  
  	skb = __netdev_alloc_skb_ip_align(dev->net, size, flags);
  	if (!skb) {
  		netif_dbg(dev, rx_err, dev->net, "no rx skb
  ");
  		usbnet_defer_kevent (dev, EVENT_RX_MEMORY);
  		usb_free_urb (urb);
  		return -ENOMEM;
  	}
  
  	entry = (struct skb_data *) skb->cb;
  	entry->urb = urb;
  	entry->dev = dev;
  	entry->length = 0;
  
  	usb_fill_bulk_urb (urb, dev->udev, dev->in,
  		skb->data, size, rx_complete, skb);
  
  	spin_lock_irqsave (&dev->rxq.lock, lockflags);
  
  	if (netif_running (dev->net) &&
  	    netif_device_present (dev->net) &&
  	    !test_bit (EVENT_RX_HALT, &dev->flags) &&
  	    !test_bit (EVENT_DEV_ASLEEP, &dev->flags)) {
  		switch (retval = usb_submit_urb (urb, GFP_ATOMIC)) {
  		case -EPIPE:
  			usbnet_defer_kevent (dev, EVENT_RX_HALT);
  			break;
  		case -ENOMEM:
  			usbnet_defer_kevent (dev, EVENT_RX_MEMORY);
  			break;
  		case -ENODEV:
  			netif_dbg(dev, ifdown, dev->net, "device gone
  ");
  			netif_device_detach (dev->net);
  			break;
  		case -EHOSTUNREACH:
  			retval = -ENOLINK;
  			break;
  		default:
  			netif_dbg(dev, rx_err, dev->net,
  				  "rx submit, %d
  ", retval);
  			tasklet_schedule (&dev->bh);
  			break;
  		case 0:
  			__usbnet_queue_skb(&dev->rxq, skb, rx_start);
  		}
  	} else {
  		netif_dbg(dev, ifdown, dev->net, "rx: stopped
  ");
  		retval = -ENOLINK;
  	}
  	spin_unlock_irqrestore (&dev->rxq.lock, lockflags);
  	if (retval) {
  		dev_kfree_skb_any (skb);
  		usb_free_urb (urb);
  	}
  	return retval;
  }
  
  
  /*-------------------------------------------------------------------------*/
  
  static inline void rx_process (struct usbnet *dev, struct sk_buff *skb)
  {
  	if (dev->driver_info->rx_fixup &&
  	    !dev->driver_info->rx_fixup (dev, skb)) {
  		/* With RX_ASSEMBLE, rx_fixup() must update counters */
  		if (!(dev->driver_info->flags & FLAG_RX_ASSEMBLE))
  			dev->net->stats.rx_errors++;
  		goto done;
  	}
  	// else network stack removes extra byte if we forced a short packet
  
  	/* all data was already cloned from skb inside the driver */
  	if (dev->driver_info->flags & FLAG_MULTI_PACKET)
  		goto done;
  
  	if (skb->len < ETH_HLEN) {
  		dev->net->stats.rx_errors++;
  		dev->net->stats.rx_length_errors++;
  		netif_dbg(dev, rx_err, dev->net, "rx length %d
  ", skb->len);
  	} else {
  		usbnet_skb_return(dev, skb);
  		return;
  	}
  
  done:
  	skb_queue_tail(&dev->done, skb);
  }
  
  /*-------------------------------------------------------------------------*/
  
  static void rx_complete (struct urb *urb)
  {
  	struct sk_buff		*skb = (struct sk_buff *) urb->context;
  	struct skb_data		*entry = (struct skb_data *) skb->cb;
  	struct usbnet		*dev = entry->dev;
  	int			urb_status = urb->status;
  	enum skb_state		state;
  
  	skb_put (skb, urb->actual_length);
  	state = rx_done;
  	entry->urb = NULL;
  
  	switch (urb_status) {
  	/* success */
  	case 0:
  		break;
  
  	/* stalls need manual reset. this is rare ... except that
  	 * when going through USB 2.0 TTs, unplug appears this way.
  	 * we avoid the highspeed version of the ETIMEDOUT/EILSEQ
  	 * storm, recovering as needed.
  	 */
  	case -EPIPE:
  		dev->net->stats.rx_errors++;
  		usbnet_defer_kevent (dev, EVENT_RX_HALT);
  		// FALLTHROUGH
  
  	/* software-driven interface shutdown */
  	case -ECONNRESET:		/* async unlink */
  	case -ESHUTDOWN:		/* hardware gone */
  		netif_dbg(dev, ifdown, dev->net,
  			  "rx shutdown, code %d
  ", urb_status);
  		goto block;
  
  	/* we get controller i/o faults during hub_wq disconnect() delays.
  	 * throttle down resubmits, to avoid log floods; just temporarily,
  	 * so we still recover when the fault isn't a hub_wq delay.
  	 */
  	case -EPROTO:
  	case -ETIME:
  	case -EILSEQ:
  		dev->net->stats.rx_errors++;
  		if (!timer_pending (&dev->delay)) {
  			mod_timer (&dev->delay, jiffies + THROTTLE_JIFFIES);
  			netif_dbg(dev, link, dev->net,
  				  "rx throttle %d
  ", urb_status);
  		}
  block:
  		state = rx_cleanup;
  		entry->urb = urb;
  		urb = NULL;
  		break;
  
  	/* data overrun ... flush fifo? */
  	case -EOVERFLOW:
  		dev->net->stats.rx_over_errors++;
  		// FALLTHROUGH
  
  	default:
  		state = rx_cleanup;
  		dev->net->stats.rx_errors++;
  		netif_dbg(dev, rx_err, dev->net, "rx status %d
  ", urb_status);
  		break;
  	}
  
  	/* stop rx if packet error rate is high */
  	if (++dev->pkt_cnt > 30) {
  		dev->pkt_cnt = 0;
  		dev->pkt_err = 0;
  	} else {
  		if (state == rx_cleanup)
  			dev->pkt_err++;
  		if (dev->pkt_err > 20)
  			set_bit(EVENT_RX_KILL, &dev->flags);
  	}
  
  	state = defer_bh(dev, skb, &dev->rxq, state);
  
  	if (urb) {
  		if (netif_running (dev->net) &&
  		    !test_bit (EVENT_RX_HALT, &dev->flags) &&
  		    state != unlink_start) {
  			rx_submit (dev, urb, GFP_ATOMIC);
  			usb_mark_last_busy(dev->udev);
  			return;
  		}
  		usb_free_urb (urb);
  	}
  	netif_dbg(dev, rx_err, dev->net, "no read resubmitted
  ");
  }
  
  /*-------------------------------------------------------------------------*/
  void usbnet_pause_rx(struct usbnet *dev)
  {
  	set_bit(EVENT_RX_PAUSED, &dev->flags);
  
  	netif_dbg(dev, rx_status, dev->net, "paused rx queue enabled
  ");
  }
  EXPORT_SYMBOL_GPL(usbnet_pause_rx);
  
  void usbnet_resume_rx(struct usbnet *dev)
  {
  	struct sk_buff *skb;
  	int num = 0;
  
  	clear_bit(EVENT_RX_PAUSED, &dev->flags);
  
  	while ((skb = skb_dequeue(&dev->rxq_pause)) != NULL) {
  		usbnet_skb_return(dev, skb);
  		num++;
  	}
  
  	tasklet_schedule(&dev->bh);
  
  	netif_dbg(dev, rx_status, dev->net,
  		  "paused rx queue disabled, %d skbs requeued
  ", num);
  }
  EXPORT_SYMBOL_GPL(usbnet_resume_rx);
  
  void usbnet_purge_paused_rxq(struct usbnet *dev)
  {
  	skb_queue_purge(&dev->rxq_pause);
  }
  EXPORT_SYMBOL_GPL(usbnet_purge_paused_rxq);
  
  /*-------------------------------------------------------------------------*/
  
  // unlink pending rx/tx; completion handlers do all other cleanup
  
  static int unlink_urbs (struct usbnet *dev, struct sk_buff_head *q)
  {
  	unsigned long		flags;
  	struct sk_buff		*skb;
  	int			count = 0;
  
  	spin_lock_irqsave (&q->lock, flags);
  	while (!skb_queue_empty(q)) {
  		struct skb_data		*entry;
  		struct urb		*urb;
  		int			retval;
  
  		skb_queue_walk(q, skb) {
  			entry = (struct skb_data *) skb->cb;
  			if (entry->state != unlink_start)
  				goto found;
  		}
  		break;
  found:
  		entry->state = unlink_start;
  		urb = entry->urb;
  
  		/*
  		 * Get reference count of the URB to avoid it to be
  		 * freed during usb_unlink_urb, which may trigger
  		 * use-after-free problem inside usb_unlink_urb since
  		 * usb_unlink_urb is always racing with .complete
  		 * handler(include defer_bh).
  		 */
  		usb_get_urb(urb);
  		spin_unlock_irqrestore(&q->lock, flags);
  		// during some PM-driven resume scenarios,
  		// these (async) unlinks complete immediately
  		retval = usb_unlink_urb (urb);
  		if (retval != -EINPROGRESS && retval != 0)
  			netdev_dbg(dev->net, "unlink urb err, %d
  ", retval);
  		else
  			count++;
  		usb_put_urb(urb);
  		spin_lock_irqsave(&q->lock, flags);
  	}
  	spin_unlock_irqrestore (&q->lock, flags);
  	return count;
  }
  
  // Flush all pending rx urbs
  // minidrivers may need to do this when the MTU changes
  
  void usbnet_unlink_rx_urbs(struct usbnet *dev)
  {
  	if (netif_running(dev->net)) {
  		(void) unlink_urbs (dev, &dev->rxq);
  		tasklet_schedule(&dev->bh);
  	}
  }
  EXPORT_SYMBOL_GPL(usbnet_unlink_rx_urbs);
  
  /*-------------------------------------------------------------------------*/
  
  static void wait_skb_queue_empty(struct sk_buff_head *q)
  {
  	unsigned long flags;
  
  	spin_lock_irqsave(&q->lock, flags);
  	while (!skb_queue_empty(q)) {
  		spin_unlock_irqrestore(&q->lock, flags);
  		schedule_timeout(msecs_to_jiffies(UNLINK_TIMEOUT_MS));
  		set_current_state(TASK_UNINTERRUPTIBLE);
  		spin_lock_irqsave(&q->lock, flags);
  	}
  	spin_unlock_irqrestore(&q->lock, flags);
  }
  
  // precondition: never called in_interrupt
  static void usbnet_terminate_urbs(struct usbnet *dev)
  {
  	DECLARE_WAITQUEUE(wait, current);
  	int temp;
  
  	/* ensure there are no more active urbs */
  	add_wait_queue(&dev->wait, &wait);
  	set_current_state(TASK_UNINTERRUPTIBLE);
  	temp = unlink_urbs(dev, &dev->txq) +
  		unlink_urbs(dev, &dev->rxq);
  
  	/* maybe wait for deletions to finish. */
  	wait_skb_queue_empty(&dev->rxq);
  	wait_skb_queue_empty(&dev->txq);
  	wait_skb_queue_empty(&dev->done);
  	netif_dbg(dev, ifdown, dev->net,
  		  "waited for %d urb completions
  ", temp);
  	set_current_state(TASK_RUNNING);
  	remove_wait_queue(&dev->wait, &wait);
  }
  
  int usbnet_stop (struct net_device *net)
  {
  	struct usbnet		*dev = netdev_priv(net);
  	struct driver_info	*info = dev->driver_info;
  	int			retval, pm, mpn;
  
  	clear_bit(EVENT_DEV_OPEN, &dev->flags);
  	netif_stop_queue (net);
  
  	netif_info(dev, ifdown, dev->net,
  		   "stop stats: rx/tx %lu/%lu, errs %lu/%lu
  ",
  		   net->stats.rx_packets, net->stats.tx_packets,
  		   net->stats.rx_errors, net->stats.tx_errors);
  
  	/* to not race resume */
  	pm = usb_autopm_get_interface(dev->intf);
  	/* allow minidriver to stop correctly (wireless devices to turn off
  	 * radio etc) */
  	if (info->stop) {
  		retval = info->stop(dev);
  		if (retval < 0)
  			netif_info(dev, ifdown, dev->net,
  				   "stop fail (%d) usbnet usb-%s-%s, %s
  ",
  				   retval,
  				   dev->udev->bus->bus_name, dev->udev->devpath,
  				   info->description);
  	}
  
  	if (!(info->flags & FLAG_AVOID_UNLINK_URBS))
  		usbnet_terminate_urbs(dev);
  
  	usbnet_status_stop(dev);
  
  	usbnet_purge_paused_rxq(dev);
  
  	mpn = !test_and_clear_bit(EVENT_NO_RUNTIME_PM, &dev->flags);
  
  	/* deferred work (task, timer, softirq) must also stop.
  	 * can't flush_scheduled_work() until we drop rtnl (later),
  	 * else workers could deadlock; so make workers a NOP.
  	 */
  	dev->flags = 0;
  	del_timer_sync (&dev->delay);
  	tasklet_kill (&dev->bh);
  	if (!pm)
  		usb_autopm_put_interface(dev->intf);
  
  	if (info->manage_power && mpn)
  		info->manage_power(dev, 0);
  	else
  		usb_autopm_put_interface(dev->intf);
  
  	return 0;
  }
  EXPORT_SYMBOL_GPL(usbnet_stop);
  
  /*-------------------------------------------------------------------------*/
  
  // posts reads, and enables write queuing
  
  // precondition: never called in_interrupt
  
  int usbnet_open (struct net_device *net)
  {
  	struct usbnet		*dev = netdev_priv(net);
  	int			retval;
  	struct driver_info	*info = dev->driver_info;
  
  	if ((retval = usb_autopm_get_interface(dev->intf)) < 0) {
  		netif_info(dev, ifup, dev->net,
  			   "resumption fail (%d) usbnet usb-%s-%s, %s
  ",
  			   retval,
  			   dev->udev->bus->bus_name,
  			   dev->udev->devpath,
  			   info->description);
  		goto done_nopm;
  	}
  
  	// put into "known safe" state
  	if (info->reset && (retval = info->reset (dev)) < 0) {
  		netif_info(dev, ifup, dev->net,
  			   "open reset fail (%d) usbnet usb-%s-%s, %s
  ",
  			   retval,
  			   dev->udev->bus->bus_name,
  			   dev->udev->devpath,
  			   info->description);
  		goto done;
  	}
  
  	/* hard_mtu or rx_urb_size may change in reset() */
  	usbnet_update_max_qlen(dev);
  
  	// insist peer be connected
  	if (info->check_connect && (retval = info->check_connect (dev)) < 0) {
  		netif_dbg(dev, ifup, dev->net, "can't open; %d
  ", retval);
  		goto done;
  	}
  
  	/* start any status interrupt transfer */
  	if (dev->interrupt) {
  		retval = usbnet_status_start(dev, GFP_KERNEL);
  		if (retval < 0) {
  			netif_err(dev, ifup, dev->net,
  				  "intr submit %d
  ", retval);
  			goto done;
  		}
  	}
  
  	set_bit(EVENT_DEV_OPEN, &dev->flags);
  	netif_start_queue (net);
  	netif_info(dev, ifup, dev->net,
  		   "open: enable queueing (rx %d, tx %d) mtu %d %s framing
  ",
  		   (int)RX_QLEN(dev), (int)TX_QLEN(dev),
  		   dev->net->mtu,
  		   (dev->driver_info->flags & FLAG_FRAMING_NC) ? "NetChip" :
  		   (dev->driver_info->flags & FLAG_FRAMING_GL) ? "GeneSys" :
  		   (dev->driver_info->flags & FLAG_FRAMING_Z) ? "Zaurus" :
  		   (dev->driver_info->flags & FLAG_FRAMING_RN) ? "RNDIS" :
  		   (dev->driver_info->flags & FLAG_FRAMING_AX) ? "ASIX" :
  		   "simple");
  
  	/* reset rx error state */
  	dev->pkt_cnt = 0;
  	dev->pkt_err = 0;
  	clear_bit(EVENT_RX_KILL, &dev->flags);
  
  	// delay posting reads until we're fully open
  	tasklet_schedule (&dev->bh);
  	if (info->manage_power) {
  		retval = info->manage_power(dev, 1);
  		if (retval < 0) {
  			retval = 0;
  			set_bit(EVENT_NO_RUNTIME_PM, &dev->flags);
  		} else {
  			usb_autopm_put_interface(dev->intf);
  		}
  	}
  	return retval;
  done:
  	usb_autopm_put_interface(dev->intf);
  done_nopm:
  	return retval;
  }
  EXPORT_SYMBOL_GPL(usbnet_open);
  
  /*-------------------------------------------------------------------------*/
  
  /* ethtool methods; minidrivers may need to add some more, but
   * they'll probably want to use this base set.
   */
  
  int usbnet_get_settings (struct net_device *net, struct ethtool_cmd *cmd)
  {
  	struct usbnet *dev = netdev_priv(net);
  
  	if (!dev->mii.mdio_read)
  		return -EOPNOTSUPP;
  
  	return mii_ethtool_gset(&dev->mii, cmd);
  }
  EXPORT_SYMBOL_GPL(usbnet_get_settings);
  
  int usbnet_set_settings (struct net_device *net, struct ethtool_cmd *cmd)
  {
  	struct usbnet *dev = netdev_priv(net);
  	int retval;
  
  	if (!dev->mii.mdio_write)
  		return -EOPNOTSUPP;
  
  	retval = mii_ethtool_sset(&dev->mii, cmd);
  
  	/* link speed/duplex might have changed */
  	if (dev->driver_info->link_reset)
  		dev->driver_info->link_reset(dev);
  
  	/* hard_mtu or rx_urb_size may change in link_reset() */
  	usbnet_update_max_qlen(dev);
  
  	return retval;
  
  }
  EXPORT_SYMBOL_GPL(usbnet_set_settings);
  
  u32 usbnet_get_link (struct net_device *net)
  {
  	struct usbnet *dev = netdev_priv(net);
  
  	/* If a check_connect is defined, return its result */
  	if (dev->driver_info->check_connect)
  		return dev->driver_info->check_connect (dev) == 0;
  
  	/* if the device has mii operations, use those */
  	if (dev->mii.mdio_read)
  		return mii_link_ok(&dev->mii);
  
  	/* Otherwise, dtrt for drivers calling netif_carrier_{on,off} */
  	return ethtool_op_get_link(net);
  }
  EXPORT_SYMBOL_GPL(usbnet_get_link);
  
  int usbnet_nway_reset(struct net_device *net)
  {
  	struct usbnet *dev = netdev_priv(net);
  
  	if (!dev->mii.mdio_write)
  		return -EOPNOTSUPP;
  
  	return mii_nway_restart(&dev->mii);
  }
  EXPORT_SYMBOL_GPL(usbnet_nway_reset);
  
  void usbnet_get_drvinfo (struct net_device *net, struct ethtool_drvinfo *info)
  {
  	struct usbnet *dev = netdev_priv(net);
  
  	strlcpy (info->driver, dev->driver_name, sizeof info->driver);
  	strlcpy (info->version, DRIVER_VERSION, sizeof info->version);
  	strlcpy (info->fw_version, dev->driver_info->description,
  		sizeof info->fw_version);
  	usb_make_path (dev->udev, info->bus_info, sizeof info->bus_info);
  }
  EXPORT_SYMBOL_GPL(usbnet_get_drvinfo);
  
  u32 usbnet_get_msglevel (struct net_device *net)
  {
  	struct usbnet *dev = netdev_priv(net);
  
  	return dev->msg_enable;
  }
  EXPORT_SYMBOL_GPL(usbnet_get_msglevel);
  
  void usbnet_set_msglevel (struct net_device *net, u32 level)
  {
  	struct usbnet *dev = netdev_priv(net);
  
  	dev->msg_enable = level;
  }
  EXPORT_SYMBOL_GPL(usbnet_set_msglevel);
  
  /* drivers may override default ethtool_ops in their bind() routine */
  static const struct ethtool_ops usbnet_ethtool_ops = {
  	.get_settings		= usbnet_get_settings,
  	.set_settings		= usbnet_set_settings,
  	.get_link		= usbnet_get_link,
  	.nway_reset		= usbnet_nway_reset,
  	.get_drvinfo		= usbnet_get_drvinfo,
  	.get_msglevel		= usbnet_get_msglevel,
  	.set_msglevel		= usbnet_set_msglevel,
  	.get_ts_info		= ethtool_op_get_ts_info,
  };
  
  /*-------------------------------------------------------------------------*/
  
  static void __handle_link_change(struct usbnet *dev)
  {
  	if (!test_bit(EVENT_DEV_OPEN, &dev->flags))
  		return;
  
  	if (!netif_carrier_ok(dev->net)) {
  		/* kill URBs for reading packets to save bus bandwidth */
  		unlink_urbs(dev, &dev->rxq);
  
  		/*
  		 * tx_timeout will unlink URBs for sending packets and
  		 * tx queue is stopped by netcore after link becomes off
  		 */
  	} else {
  		/* submitting URBs for reading packets */
  		tasklet_schedule(&dev->bh);
  	}
  
  	/* hard_mtu or rx_urb_size may change during link change */
  	usbnet_update_max_qlen(dev);
  
  	clear_bit(EVENT_LINK_CHANGE, &dev->flags);
  }
  
  static void usbnet_set_rx_mode(struct net_device *net)
  {
  	struct usbnet		*dev = netdev_priv(net);
  
  	usbnet_defer_kevent(dev, EVENT_SET_RX_MODE);
  }
  
  static void __handle_set_rx_mode(struct usbnet *dev)
  {
  	if (dev->driver_info->set_rx_mode)
  		(dev->driver_info->set_rx_mode)(dev);
  
  	clear_bit(EVENT_SET_RX_MODE, &dev->flags);
  }
  
  /* work that cannot be done in interrupt context uses keventd.
   *
   * NOTE:  with 2.5 we could do more of this using completion callbacks,
   * especially now that control transfers can be queued.
   */
  static void
  usbnet_deferred_kevent (struct work_struct *work)
  {
  	struct usbnet		*dev =
  		container_of(work, struct usbnet, kevent);
  	int			status;
  
  	/* usb_clear_halt() needs a thread context */
  	if (test_bit (EVENT_TX_HALT, &dev->flags)) {
  		unlink_urbs (dev, &dev->txq);
  		status = usb_autopm_get_interface(dev->intf);
  		if (status < 0)
  			goto fail_pipe;
  		status = usb_clear_halt (dev->udev, dev->out);
  		usb_autopm_put_interface(dev->intf);
  		if (status < 0 &&
  		    status != -EPIPE &&
  		    status != -ESHUTDOWN) {
  			if (netif_msg_tx_err (dev))
  fail_pipe:
  				netdev_err(dev->net, "can't clear tx halt, status %d
  ",
  					   status);
  		} else {
  			clear_bit (EVENT_TX_HALT, &dev->flags);
  			if (status != -ESHUTDOWN)
  				netif_wake_queue (dev->net);
  		}
  	}
  	if (test_bit (EVENT_RX_HALT, &dev->flags)) {
  		unlink_urbs (dev, &dev->rxq);
  		status = usb_autopm_get_interface(dev->intf);
  		if (status < 0)
  			goto fail_halt;
  		status = usb_clear_halt (dev->udev, dev->in);
  		usb_autopm_put_interface(dev->intf);
  		if (status < 0 &&
  		    status != -EPIPE &&
  		    status != -ESHUTDOWN) {
  			if (netif_msg_rx_err (dev))
  fail_halt:
  				netdev_err(dev->net, "can't clear rx halt, status %d
  ",
  					   status);
  		} else {
  			clear_bit (EVENT_RX_HALT, &dev->flags);
  			tasklet_schedule (&dev->bh);
  		}
  	}
  
  	/* tasklet could resubmit itself forever if memory is tight */
  	if (test_bit (EVENT_RX_MEMORY, &dev->flags)) {
  		struct urb	*urb = NULL;
  		int resched = 1;
  
  		if (netif_running (dev->net))
  			urb = usb_alloc_urb (0, GFP_KERNEL);
  		else
  			clear_bit (EVENT_RX_MEMORY, &dev->flags);
  		if (urb != NULL) {
  			clear_bit (EVENT_RX_MEMORY, &dev->flags);
  			status = usb_autopm_get_interface(dev->intf);
  			if (status < 0) {
  				usb_free_urb(urb);
  				goto fail_lowmem;
  			}
  			if (rx_submit (dev, urb, GFP_KERNEL) == -ENOLINK)
  				resched = 0;
  			usb_autopm_put_interface(dev->intf);
  fail_lowmem:
  			if (resched)
  				tasklet_schedule (&dev->bh);
  		}
  	}
  
  	if (test_bit (EVENT_LINK_RESET, &dev->flags)) {
  		struct driver_info	*info = dev->driver_info;
  		int			retval = 0;
  
  		clear_bit (EVENT_LINK_RESET, &dev->flags);
  		status = usb_autopm_get_interface(dev->intf);
  		if (status < 0)
  			goto skip_reset;
  		if(info->link_reset && (retval = info->link_reset(dev)) < 0) {
  			usb_autopm_put_interface(dev->intf);
  skip_reset:
  			netdev_info(dev->net, "link reset failed (%d) usbnet usb-%s-%s, %s
  ",
  				    retval,
  				    dev->udev->bus->bus_name,
  				    dev->udev->devpath,
  				    info->description);
  		} else {
  			usb_autopm_put_interface(dev->intf);
  		}
  
  		/* handle link change from link resetting */
  		__handle_link_change(dev);
  	}
  
  	if (test_bit (EVENT_LINK_CHANGE, &dev->flags))
  		__handle_link_change(dev);
  
  	if (test_bit (EVENT_SET_RX_MODE, &dev->flags))
  		__handle_set_rx_mode(dev);
  
  
  	if (dev->flags)
  		netdev_dbg(dev->net, "kevent done, flags = 0x%lx
  ", dev->flags);
  }
  
  /*-------------------------------------------------------------------------*/
  
  static void tx_complete (struct urb *urb)
  {
  	struct sk_buff		*skb = (struct sk_buff *) urb->context;
  	struct skb_data		*entry = (struct skb_data *) skb->cb;
  	struct usbnet		*dev = entry->dev;
  
  	if (urb->status == 0) {
  		dev->net->stats.tx_packets += entry->packets;
  		dev->net->stats.tx_bytes += entry->length;
  	} else {
  		dev->net->stats.tx_errors++;
  
  		switch (urb->status) {
  		case -EPIPE:
  			usbnet_defer_kevent (dev, EVENT_TX_HALT);
  			break;
  
  		/* software-driven interface shutdown */
  		case -ECONNRESET:		// async unlink
  		case -ESHUTDOWN:		// hardware gone
  			break;
  
  		/* like rx, tx gets controller i/o faults during hub_wq
  		 * delays and so it uses the same throttling mechanism.
  		 */
  		case -EPROTO:
  		case -ETIME:
  		case -EILSEQ:
  			usb_mark_last_busy(dev->udev);
  			if (!timer_pending (&dev->delay)) {
  				mod_timer (&dev->delay,
  					jiffies + THROTTLE_JIFFIES);
  				netif_dbg(dev, link, dev->net,
  					  "tx throttle %d
  ", urb->status);
  			}
  			netif_stop_queue (dev->net);
  			break;
  		default:
  			netif_dbg(dev, tx_err, dev->net,
  				  "tx err %d
  ", entry->urb->status);
  			break;
  		}
  	}
  
  	usb_autopm_put_interface_async(dev->intf);
  	(void) defer_bh(dev, skb, &dev->txq, tx_done);
  }
  
  /*-------------------------------------------------------------------------*/
  
  void usbnet_tx_timeout (struct net_device *net)
  {
  	struct usbnet		*dev = netdev_priv(net);
  
  	unlink_urbs (dev, &dev->txq);
  	tasklet_schedule (&dev->bh);
  	/* this needs to be handled individually because the generic layer
  	 * doesn't know what is sufficient and could not restore private
  	 * information if a remedy of an unconditional reset were used.
  	 */
  	if (dev->driver_info->recover)
  		(dev->driver_info->recover)(dev);
  }
  EXPORT_SYMBOL_GPL(usbnet_tx_timeout);
  
  /*-------------------------------------------------------------------------*/
  
  static int build_dma_sg(const struct sk_buff *skb, struct urb *urb)
  {
  	unsigned num_sgs, total_len = 0;
  	int i, s = 0;
  
  	num_sgs = skb_shinfo(skb)->nr_frags + 1;
  	if (num_sgs == 1)
  		return 0;
  
  	/* reserve one for zero packet */
  	urb->sg = kmalloc((num_sgs + 1) * sizeof(struct scatterlist),
  			  GFP_ATOMIC);
  	if (!urb->sg)
  		return -ENOMEM;
  
  	urb->num_sgs = num_sgs;
  	sg_init_table(urb->sg, urb->num_sgs + 1);
  
  	sg_set_buf(&urb->sg[s++], skb->data, skb_headlen(skb));
  	total_len += skb_headlen(skb);
  
  	for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
  		struct skb_frag_struct *f = &skb_shinfo(skb)->frags[i];
  
  		total_len += skb_frag_size(f);
  		sg_set_page(&urb->sg[i + s], f->page.p, f->size,
  				f->page_offset);
  	}
  	urb->transfer_buffer_length = total_len;
  
  	return 1;
  }
  
  netdev_tx_t usbnet_start_xmit (struct sk_buff *skb,
  				     struct net_device *net)
  {
  	struct usbnet		*dev = netdev_priv(net);
  	unsigned int			length;
  	struct urb		*urb = NULL;
  	struct skb_data		*entry;
  	struct driver_info	*info = dev->driver_info;
  	unsigned long		flags;
  	int retval;
  
  	if (skb)
  		skb_tx_timestamp(skb);
  
  	// some devices want funky USB-level framing, for
  	// win32 driver (usually) and/or hardware quirks
  	if (info->tx_fixup) {
  		skb = info->tx_fixup (dev, skb, GFP_ATOMIC);
  		if (!skb) {
  			/* packet collected; minidriver waiting for more */
  			if (info->flags & FLAG_MULTI_PACKET)
  				goto not_drop;
  			netif_dbg(dev, tx_err, dev->net, "can't tx_fixup skb
  ");
  			goto drop;
  		}
  	}
  
  	if (!(urb = usb_alloc_urb (0, GFP_ATOMIC))) {
  		netif_dbg(dev, tx_err, dev->net, "no urb
  ");
  		goto drop;
  	}
  
  	entry = (struct skb_data *) skb->cb;
  	entry->urb = urb;
  	entry->dev = dev;
  
  	usb_fill_bulk_urb (urb, dev->udev, dev->out,
  			skb->data, skb->len, tx_complete, skb);
  	if (dev->can_dma_sg) {
  		if (build_dma_sg(skb, urb) < 0)
  			goto drop;
  	}
  	length = urb->transfer_buffer_length;
  
  	/* don't assume the hardware handles USB_ZERO_PACKET
  	 * NOTE:  strictly conforming cdc-ether devices should expect
  	 * the ZLP here, but ignore the one-byte packet.
  	 * NOTE2: CDC NCM specification is different from CDC ECM when
  	 * handling ZLP/short packets, so cdc_ncm driver will make short
  	 * packet itself if needed.
  	 */
  	if (length % dev->maxpacket == 0) {
  		if (!(info->flags & FLAG_SEND_ZLP)) {
  			if (!(info->flags & FLAG_MULTI_PACKET)) {
  				length++;
  				if (skb_tailroom(skb) && !urb->num_sgs) {
  					skb->data[skb->len] = 0;
  					__skb_put(skb, 1);
  				} else if (urb->num_sgs)
  					sg_set_buf(&urb->sg[urb->num_sgs++],
  							dev->padding_pkt, 1);
  			}
  		} else
  			urb->transfer_flags |= URB_ZERO_PACKET;
  	}
  	urb->transfer_buffer_length = length;
  
  	if (info->flags & FLAG_MULTI_PACKET) {
  		/* Driver has set number of packets and a length delta.
  		 * Calculate the complete length and ensure that it's
  		 * positive.
  		 */
  		entry->length += length;
  		if (WARN_ON_ONCE(entry->length <= 0))
  			entry->length = length;
  	} else {
  		usbnet_set_skb_tx_stats(skb, 1, length);
  	}
  
  	spin_lock_irqsave(&dev->txq.lock, flags);
  	retval = usb_autopm_get_interface_async(dev->intf);
  	if (retval < 0) {
  		spin_unlock_irqrestore(&dev->txq.lock, flags);
  		goto drop;
  	}
  
  #ifdef CONFIG_PM
  	/* if this triggers the device is still a sleep */
  	if (test_bit(EVENT_DEV_ASLEEP, &dev->flags)) {
  		/* transmission will be done in resume */
  		usb_anchor_urb(urb, &dev->deferred);
  		/* no use to process more packets */
  		netif_stop_queue(net);
  		usb_put_urb(urb);
  		spin_unlock_irqrestore(&dev->txq.lock, flags);
  		netdev_dbg(dev->net, "Delaying transmission for resumption
  ");
  		goto deferred;
  	}
  #endif
  
  	switch ((retval = usb_submit_urb (urb, GFP_ATOMIC))) {
  	case -EPIPE:
  		netif_stop_queue (net);
  		usbnet_defer_kevent (dev, EVENT_TX_HALT);
  		usb_autopm_put_interface_async(dev->intf);
  		break;
  	default:
  		usb_autopm_put_interface_async(dev->intf);
  		netif_dbg(dev, tx_err, dev->net,
  			  "tx: submit urb err %d
  ", retval);
  		break;
  	case 0:
  		net->trans_start = jiffies;
  		__usbnet_queue_skb(&dev->txq, skb, tx_start);
  		if (dev->txq.qlen >= TX_QLEN (dev))
  			netif_stop_queue (net);
  	}
  	spin_unlock_irqrestore (&dev->txq.lock, flags);
  
  	if (retval) {
  		netif_dbg(dev, tx_err, dev->net, "drop, code %d
  ", retval);
  drop:
  		dev->net->stats.tx_dropped++;
  not_drop:
  		if (skb)
  			dev_kfree_skb_any (skb);
  		if (urb) {
  			kfree(urb->sg);
  			usb_free_urb(urb);
  		}
  	} else
  		netif_dbg(dev, tx_queued, dev->net,
  			  "> tx, len %u, type 0x%x
  ", length, skb->protocol);
  #ifdef CONFIG_PM
  deferred:
  #endif
  	return NETDEV_TX_OK;
  }
  EXPORT_SYMBOL_GPL(usbnet_start_xmit);
  
  static int rx_alloc_submit(struct usbnet *dev, gfp_t flags)
  {
  	struct urb	*urb;
  	int		i;
  	int		ret = 0;
  
  	/* don't refill the queue all at once */
  	for (i = 0; i < 10 && dev->rxq.qlen < RX_QLEN(dev); i++) {
  		urb = usb_alloc_urb(0, flags);
  		if (urb != NULL) {
  			ret = rx_submit(dev, urb, flags);
  			if (ret)
  				goto err;
  		} else {
  			ret = -ENOMEM;
  			goto err;
  		}
  	}
  err:
  	return ret;
  }
  
  /*-------------------------------------------------------------------------*/
  
  // tasklet (work deferred from completions, in_irq) or timer
  
  static void usbnet_bh (unsigned long param)
  {
  	struct usbnet		*dev = (struct usbnet *) param;
  	struct sk_buff		*skb;
  	struct skb_data		*entry;
  
  	while ((skb = skb_dequeue (&dev->done))) {
  		entry = (struct skb_data *) skb->cb;
  		switch (entry->state) {
  		case rx_done:
  			entry->state = rx_cleanup;
  			rx_process (dev, skb);
  			continue;
  		case tx_done:
  			kfree(entry->urb->sg);
  		case rx_cleanup:
  			usb_free_urb (entry->urb);
  			dev_kfree_skb (skb);
  			continue;
  		default:
  			netdev_dbg(dev->net, "bogus skb state %d
  ", entry->state);
  		}
  	}
  
  	/* restart RX again after disabling due to high error rate */
  	clear_bit(EVENT_RX_KILL, &dev->flags);
  
  	/* waiting for all pending urbs to complete?
  	 * only then can we forgo submitting anew
  	 */
  	if (waitqueue_active(&dev->wait)) {
  		if (dev->txq.qlen + dev->rxq.qlen + dev->done.qlen == 0)
  			wake_up_all(&dev->wait);
  
  	// or are we maybe short a few urbs?
  	} else if (netif_running (dev->net) &&
  		   netif_device_present (dev->net) &&
  		   netif_carrier_ok(dev->net) &&
  		   !timer_pending (&dev->delay) &&
  		   !test_bit (EVENT_RX_HALT, &dev->flags)) {
  		int	temp = dev->rxq.qlen;
  
  		if (temp < RX_QLEN(dev)) {
  			if (rx_alloc_submit(dev, GFP_ATOMIC) == -ENOLINK)
  				return;
  			if (temp != dev->rxq.qlen)
  				netif_dbg(dev, link, dev->net,
  					  "rxqlen %d --> %d
  ",
  					  temp, dev->rxq.qlen);
  			if (dev->rxq.qlen < RX_QLEN(dev))
  				tasklet_schedule (&dev->bh);
  		}
  		if (dev->txq.qlen < TX_QLEN (dev))
  			netif_wake_queue (dev->net);
  	}
  }
  
  
  /*-------------------------------------------------------------------------
   *
   * USB Device Driver support
   *
   *-------------------------------------------------------------------------*/
  
  // precondition: never called in_interrupt
  
  void usbnet_disconnect (struct usb_interface *intf)
  {
  	struct usbnet		*dev;
  	struct usb_device	*xdev;
  	struct net_device	*net;
  
  	dev = usb_get_intfdata(intf);
  	usb_set_intfdata(intf, NULL);
  	if (!dev)
  		return;
  
  	xdev = interface_to_usbdev (intf);
  
  	netif_info(dev, probe, dev->net, "unregister '%s' usb-%s-%s, %s
  ",
  		   intf->dev.driver->name,
  		   xdev->bus->bus_name, xdev->devpath,
  		   dev->driver_info->description);
  
  	net = dev->net;
  	unregister_netdev (net);
  
  	cancel_work_sync(&dev->kevent);
  
  	usb_scuttle_anchored_urbs(&dev->deferred);
  
  	if (dev->driver_info->unbind)
  		dev->driver_info->unbind (dev, intf);
  
  	usb_kill_urb(dev->interrupt);
  	usb_free_urb(dev->interrupt);
  	kfree(dev->padding_pkt);
  
  	free_netdev(net);
  }
  EXPORT_SYMBOL_GPL(usbnet_disconnect);
  
  static const struct net_device_ops usbnet_netdev_ops = {
  	.ndo_open		= usbnet_open,
  	.ndo_stop		= usbnet_stop,
  	.ndo_start_xmit		= usbnet_start_xmit,
  	.ndo_tx_timeout		= usbnet_tx_timeout,
  	.ndo_set_rx_mode	= usbnet_set_rx_mode,
  	.ndo_change_mtu		= usbnet_change_mtu,
  	.ndo_set_mac_address 	= eth_mac_addr,
  	.ndo_validate_addr	= eth_validate_addr,
  };
  
  /*-------------------------------------------------------------------------*/
  
  // precondition: never called in_interrupt
  
  static struct device_type wlan_type = {
  	.name	= "wlan",
  };
  
  static struct device_type wwan_type = {
  	.name	= "wwan",
  };
  
  int
  usbnet_probe (struct usb_interface *udev, const struct usb_device_id *prod)
  {
  	struct usbnet			*dev;
  	struct net_device		*net;
  	struct usb_host_interface	*interface;
  	struct driver_info		*info;
  	struct usb_device		*xdev;
  	int				status;
  	const char			*name;
  	struct usb_driver 	*driver = to_usb_driver(udev->dev.driver);
  
  	/* usbnet already took usb runtime pm, so have to enable the feature
  	 * for usb interface, otherwise usb_autopm_get_interface may return
  	 * failure if RUNTIME_PM is enabled.
  	 */
  	if (!driver->supports_autosuspend) {
  		driver->supports_autosuspend = 1;
  		pm_runtime_enable(&udev->dev);
  	}
  
  	name = udev->dev.driver->name;
  	info = (struct driver_info *) prod->driver_info;
  	if (!info) {
  		dev_dbg (&udev->dev, "blacklisted by %s
  ", name);
  		return -ENODEV;
  	}
  	xdev = interface_to_usbdev (udev);
  	interface = udev->cur_altsetting;
  
  	status = -ENOMEM;
  
  	// set up our own records
  	net = alloc_etherdev(sizeof(*dev));
  	if (!net)
  		goto out;
  
  	/* netdev_printk() needs this so do it as early as possible */
  	SET_NETDEV_DEV(net, &udev->dev);
  
  	dev = netdev_priv(net);
  	dev->udev = xdev;
  	dev->intf = udev;
  	dev->driver_info = info;
  	dev->driver_name = name;
  	dev->msg_enable = netif_msg_init (msg_level, NETIF_MSG_DRV
  				| NETIF_MSG_PROBE | NETIF_MSG_LINK);
  	init_waitqueue_head(&dev->wait);
  	skb_queue_head_init (&dev->rxq);
  	skb_queue_head_init (&dev->txq);
  	skb_queue_head_init (&dev->done);
  	skb_queue_head_init(&dev->rxq_pause);
  	dev->bh.func = usbnet_bh;
  	dev->bh.data = (unsigned long) dev;
  	INIT_WORK (&dev->kevent, usbnet_deferred_kevent);
  	init_usb_anchor(&dev->deferred);
  	dev->delay.function = usbnet_bh;
  	dev->delay.data = (unsigned long) dev;
  	init_timer (&dev->delay);
  	mutex_init (&dev->phy_mutex);
  	mutex_init(&dev->interrupt_mutex);
  	dev->interrupt_count = 0;
  
  	dev->net = net;
  	strcpy (net->name, "usb%d");
  	memcpy (net->dev_addr, node_id, sizeof node_id);
  
  	/* rx and tx sides can use different message sizes;
  	 * bind() should set rx_urb_size in that case.
  	 */
  	dev->hard_mtu = net->mtu + net->hard_header_len;
  
  	net->netdev_ops = &usbnet_netdev_ops;
  	net->watchdog_timeo = TX_TIMEOUT_JIFFIES;
  	net->ethtool_ops = &usbnet_ethtool_ops;
  
  	// allow device-specific bind/init procedures
  	// NOTE net->name still not usable ...
  	if (info->bind) {
  		status = info->bind (dev, udev);
  		if (status < 0)
  			goto out1;
  
  		// heuristic:  "usb%d" for links we know are two-host,
  		// else "eth%d" when there's reasonable doubt.  userspace
  		// can rename the link if it knows better.
  		if ((dev->driver_info->flags & FLAG_ETHER) != 0 &&
  		    ((dev->driver_info->flags & FLAG_POINTTOPOINT) == 0 ||
  		     (net->dev_addr [0] & 0x02) == 0))
  			strcpy (net->name, "eth%d");
  		/* WLAN devices should always be named "wlan%d" */
  		if ((dev->driver_info->flags & FLAG_WLAN) != 0)
  			strcpy(net->name, "wlan%d");
  		/* WWAN devices should always be named "wwan%d" */
  		if ((dev->driver_info->flags & FLAG_WWAN) != 0)
  			strcpy(net->name, "wwan%d");
  
  		/* devices that cannot do ARP */
  		if ((dev->driver_info->flags & FLAG_NOARP) != 0)
  			net->flags |= IFF_NOARP;
  
  		/* maybe the remote can't receive an Ethernet MTU */
  		if (net->mtu > (dev->hard_mtu - net->hard_header_len))
  			net->mtu = dev->hard_mtu - net->hard_header_len;
  	} else if (!info->in || !info->out)
  		status = usbnet_get_endpoints (dev, udev);
  	else {
  		dev->in = usb_rcvbulkpipe (xdev, info->in);
  		dev->out = usb_sndbulkpipe (xdev, info->out);
  		if (!(info->flags & FLAG_NO_SETINT))
  			status = usb_set_interface (xdev,
  				interface->desc.bInterfaceNumber,
  				interface->desc.bAlternateSetting);
  		else
  			status = 0;
  
  	}
  	if (status >= 0 && dev->status)
  		status = init_status (dev, udev);
  	if (status < 0)
  		goto out3;
  
  	if (!dev->rx_urb_size)
  		dev->rx_urb_size = dev->hard_mtu;
  	dev->maxpacket = usb_maxpacket (dev->udev, dev->out, 1);
  
  	/* let userspace know we have a random address */
  	if (ether_addr_equal(net->dev_addr, node_id))
  		net->addr_assign_type = NET_ADDR_RANDOM;
  
  	if ((dev->driver_info->flags & FLAG_WLAN) != 0)
  		SET_NETDEV_DEVTYPE(net, &wlan_type);
  	if ((dev->driver_info->flags & FLAG_WWAN) != 0)
  		SET_NETDEV_DEVTYPE(net, &wwan_type);
  
  	/* initialize max rx_qlen and tx_qlen */
  	usbnet_update_max_qlen(dev);
  
  	if (dev->can_dma_sg && !(info->flags & FLAG_SEND_ZLP) &&
  		!(info->flags & FLAG_MULTI_PACKET)) {
  		dev->padding_pkt = kzalloc(1, GFP_KERNEL);
  		if (!dev->padding_pkt) {
  			status = -ENOMEM;
  			goto out4;
  		}
  	}
  
  	status = register_netdev (net);
  	if (status)
  		goto out5;
  	netif_info(dev, probe, dev->net,
  		   "register '%s' at usb-%s-%s, %s, %pM
  ",
  		   udev->dev.driver->name,
  		   xdev->bus->bus_name, xdev->devpath,
  		   dev->driver_info->description,
  		   net->dev_addr);
  
  	// ok, it's ready to go.
  	usb_set_intfdata (udev, dev);
  
  	netif_device_attach (net);
  
  	if (dev->driver_info->flags & FLAG_LINK_INTR)
  		usbnet_link_change(dev, 0, 0);
  
  	return 0;
  
  out5:
  	kfree(dev->padding_pkt);
  out4:
  	usb_free_urb(dev->interrupt);
  out3:
  	if (info->unbind)
  		info->unbind (dev, udev);
  out1:
  	/* subdrivers must undo all they did in bind() if they
  	 * fail it, but we may fail later and a deferred kevent
  	 * may trigger an error resubmitting itself and, worse,
  	 * schedule a timer. So we kill it all just in case.
  	 */
  	cancel_work_sync(&dev->kevent);
  	del_timer_sync(&dev->delay);
  	free_netdev(net);
  out:
  	return status;
  }
  EXPORT_SYMBOL_GPL(usbnet_probe);
  
  /*-------------------------------------------------------------------------*/
  
  /*
   * suspend the whole driver as soon as the first interface is suspended
   * resume only when the last interface is resumed
   */
  
  int usbnet_suspend (struct usb_interface *intf, pm_message_t message)
  {
  	struct usbnet		*dev = usb_get_intfdata(intf);
  
  	if (!dev->suspend_count++) {
  		spin_lock_irq(&dev->txq.lock);
  		/* don't autosuspend while transmitting */
  		if (dev->txq.qlen && PMSG_IS_AUTO(message)) {
  			dev->suspend_count--;
  			spin_unlock_irq(&dev->txq.lock);
  			return -EBUSY;
  		} else {
  			set_bit(EVENT_DEV_ASLEEP, &dev->flags);
  			spin_unlock_irq(&dev->txq.lock);
  		}
  		/*
  		 * accelerate emptying of the rx and queues, to avoid
  		 * having everything error out.
  		 */
  		netif_device_detach (dev->net);
  		usbnet_terminate_urbs(dev);
  		__usbnet_status_stop_force(dev);
  
  		/*
  		 * reattach so runtime management can use and
  		 * wake the device
  		 */
  		netif_device_attach (dev->net);
  	}
  	return 0;
  }
  EXPORT_SYMBOL_GPL(usbnet_suspend);
  
  int usbnet_resume (struct usb_interface *intf)
  {
  	struct usbnet		*dev = usb_get_intfdata(intf);
  	struct sk_buff          *skb;
  	struct urb              *res;
  	int                     retval;
  
  	if (!--dev->suspend_count) {
  		/* resume interrupt URB if it was previously submitted */
  		__usbnet_status_start_force(dev, GFP_NOIO);
  
  		spin_lock_irq(&dev->txq.lock);
  		while ((res = usb_get_from_anchor(&dev->deferred))) {
  
  			skb = (struct sk_buff *)res->context;
  			retval = usb_submit_urb(res, GFP_ATOMIC);
  			if (retval < 0) {
  				dev_kfree_skb_any(skb);
  				kfree(res->sg);
  				usb_free_urb(res);
  				usb_autopm_put_interface_async(dev->intf);
  			} else {
  				dev->net->trans_start = jiffies;
  				__skb_queue_tail(&dev->txq, skb);
  			}
  		}
  
  		smp_mb();
  		clear_bit(EVENT_DEV_ASLEEP, &dev->flags);
  		spin_unlock_irq(&dev->txq.lock);
  
  		if (test_bit(EVENT_DEV_OPEN, &dev->flags)) {
  			/* handle remote wakeup ASAP
  			 * we cannot race against stop
  			 */
  			if (netif_device_present(dev->net) &&
  				!timer_pending(&dev->delay) &&
  				!test_bit(EVENT_RX_HALT, &dev->flags))
  					rx_alloc_submit(dev, GFP_NOIO);
  
  			if (!(dev->txq.qlen >= TX_QLEN(dev)))
  				netif_tx_wake_all_queues(dev->net);
  			tasklet_schedule (&dev->bh);
  		}
  	}
  
  	if (test_and_clear_bit(EVENT_DEVICE_REPORT_IDLE, &dev->flags))
  		usb_autopm_get_interface_no_resume(intf);
  
  	return 0;
  }
  EXPORT_SYMBOL_GPL(usbnet_resume);
  
  /*
   * Either a subdriver implements manage_power, then it is assumed to always
   * be ready to be suspended or it reports the readiness to be suspended
   * explicitly
   */
  void usbnet_device_suggests_idle(struct usbnet *dev)
  {
  	if (!test_and_set_bit(EVENT_DEVICE_REPORT_IDLE, &dev->flags)) {
  		dev->intf->needs_remote_wakeup = 1;
  		usb_autopm_put_interface_async(dev->intf);
  	}
  }
  EXPORT_SYMBOL(usbnet_device_suggests_idle);
  
  /*
   * For devices that can do without special commands
   */
  int usbnet_manage_power(struct usbnet *dev, int on)
  {
  	dev->intf->needs_remote_wakeup = on;
  	return 0;
  }
  EXPORT_SYMBOL(usbnet_manage_power);
  
  void usbnet_link_change(struct usbnet *dev, bool link, bool need_reset)
  {
  	/* update link after link is reseted */
  	if (link && !need_reset)
  		netif_carrier_on(dev->net);
  	else
  		netif_carrier_off(dev->net);
  
  	if (need_reset && link)
  		usbnet_defer_kevent(dev, EVENT_LINK_RESET);
  	else
  		usbnet_defer_kevent(dev, EVENT_LINK_CHANGE);
  }
  EXPORT_SYMBOL(usbnet_link_change);
  
  /*-------------------------------------------------------------------------*/
  static int __usbnet_read_cmd(struct usbnet *dev, u8 cmd, u8 reqtype,
  			     u16 value, u16 index, void *data, u16 size)
  {
  	void *buf = NULL;
  	int err = -ENOMEM;
  
  	netdev_dbg(dev->net, "usbnet_read_cmd cmd=0x%02x reqtype=%02x"
  		   " value=0x%04x index=0x%04x size=%d
  ",
  		   cmd, reqtype, value, index, size);
  
  	if (data) {
  		buf = kmalloc(size, GFP_KERNEL);
  		if (!buf)
  			goto out;
  	}
  
  	err = usb_control_msg(dev->udev, usb_rcvctrlpipe(dev->udev, 0),
  			      cmd, reqtype, value, index, buf, size,
  			      USB_CTRL_GET_TIMEOUT);
  	if (err > 0 && err <= size)
  		memcpy(data, buf, err);
  	kfree(buf);
  out:
  	return err;
  }
  
  static int __usbnet_write_cmd(struct usbnet *dev, u8 cmd, u8 reqtype,
  			      u16 value, u16 index, const void *data,
  			      u16 size)
  {
  	void *buf = NULL;
  	int err = -ENOMEM;
  
  	netdev_dbg(dev->net, "usbnet_write_cmd cmd=0x%02x reqtype=%02x"
  		   " value=0x%04x index=0x%04x size=%d
  ",
  		   cmd, reqtype, value, index, size);
  
  	if (data) {
  		buf = kmemdup(data, size, GFP_KERNEL);
  		if (!buf)
  			goto out;
  	}
  
  	err = usb_control_msg(dev->udev, usb_sndctrlpipe(dev->udev, 0),
  			      cmd, reqtype, value, index, buf, size,
  			      USB_CTRL_SET_TIMEOUT);
  	kfree(buf);
  
  out:
  	return err;
  }
  
  int cdc_parse_cdc_header(struct usb_cdc_parsed_header *hdr,
  				struct usb_interface *intf,
  				u8 *buffer,
  				int buflen)
  {
  	/* duplicates are ignored */
  	struct usb_cdc_union_desc *union_header = NULL;
  
  	/* duplicates are not tolerated */
  	struct usb_cdc_header_desc *header = NULL;
  	struct usb_cdc_ether_desc *ether = NULL;
  	struct usb_cdc_mdlm_detail_desc *detail = NULL;
  	struct usb_cdc_mdlm_desc *desc = NULL;
  
  	unsigned int elength;
  	int cnt = 0;
  
  	memset(hdr, 0x00, sizeof(struct usb_cdc_parsed_header));
  	hdr->phonet_magic_present = false;
  	while (buflen > 0) {
  		elength = buffer[0];
  		if (!elength) {
  			dev_err(&intf->dev, "skipping garbage byte
  ");
  			elength = 1;
  			goto next_desc;
  		}
  		if (buffer[1] != USB_DT_CS_INTERFACE) {
  			dev_err(&intf->dev, "skipping garbage
  ");
  			goto next_desc;
  		}
  
  		switch (buffer[2]) {
  		case USB_CDC_UNION_TYPE: /* we've found it */
  			if (elength < sizeof(struct usb_cdc_union_desc))
  				goto next_desc;
  			if (union_header) {
  				dev_err(&intf->dev, "More than one union descriptor, skipping ...
  ");
  				goto next_desc;
  			}
  			union_header = (struct usb_cdc_union_desc *)buffer;
  			break;
  		case USB_CDC_COUNTRY_TYPE:
  			if (elength < sizeof(struct usb_cdc_country_functional_desc))
  				goto next_desc;
  			hdr->usb_cdc_country_functional_desc =
  				(struct usb_cdc_country_functional_desc *)buffer;
  			break;
  		case USB_CDC_HEADER_TYPE:
  			if (elength != sizeof(struct usb_cdc_header_desc))
  				goto next_desc;
  			if (header)
  				return -EINVAL;
  			header = (struct usb_cdc_header_desc *)buffer;
  			break;
  		case USB_CDC_ACM_TYPE:
  			if (elength < sizeof(struct usb_cdc_acm_descriptor))
  				goto next_desc;
  			hdr->usb_cdc_acm_descriptor =
  				(struct usb_cdc_acm_descriptor *)buffer;
  			break;
  		case USB_CDC_ETHERNET_TYPE:
  			if (elength != sizeof(struct usb_cdc_ether_desc))
  				goto next_desc;
  			if (ether)
  				return -EINVAL;
  			ether = (struct usb_cdc_ether_desc *)buffer;
  			break;
  		case USB_CDC_CALL_MANAGEMENT_TYPE:
  			if (elength < sizeof(struct usb_cdc_call_mgmt_descriptor))
  				goto next_desc;
  			hdr->usb_cdc_call_mgmt_descriptor =
  				(struct usb_cdc_call_mgmt_descriptor *)buffer;
  			break;
  		case USB_CDC_DMM_TYPE:
  			if (elength < sizeof(struct usb_cdc_dmm_desc))
  				goto next_desc;
  			hdr->usb_cdc_dmm_desc =
  				(struct usb_cdc_dmm_desc *)buffer;
  			break;
  		case USB_CDC_MDLM_TYPE:
  			if (elength < sizeof(struct usb_cdc_mdlm_desc *))
  				goto next_desc;
  			if (desc)
  				return -EINVAL;
  			desc = (struct usb_cdc_mdlm_desc *)buffer;
  			break;
  		case USB_CDC_MDLM_DETAIL_TYPE:
  			if (elength < sizeof(struct usb_cdc_mdlm_detail_desc *))
  				goto next_desc;
  			if (detail)
  				return -EINVAL;
  			detail = (struct usb_cdc_mdlm_detail_desc *)buffer;
  			break;
  		case USB_CDC_NCM_TYPE:
  			if (elength < sizeof(struct usb_cdc_ncm_desc))
  				goto next_desc;
  			hdr->usb_cdc_ncm_desc = (struct usb_cdc_ncm_desc *)buffer;
  			break;
  		case USB_CDC_MBIM_TYPE:
  			if (elength < sizeof(struct usb_cdc_mbim_desc))
  				goto next_desc;
  
  			hdr->usb_cdc_mbim_desc = (struct usb_cdc_mbim_desc *)buffer;
  			break;
  		case USB_CDC_MBIM_EXTENDED_TYPE:
  			if (elength < sizeof(struct usb_cdc_mbim_extended_desc))
  				break;
  			hdr->usb_cdc_mbim_extended_desc =
  				(struct usb_cdc_mbim_extended_desc *)buffer;
  			break;
  		case CDC_PHONET_MAGIC_NUMBER:
  			hdr->phonet_magic_present = true;
  			break;
  		default:
  			/*
  			 * there are LOTS more CDC descriptors that
  			 * could legitimately be found here.
  			 */
  			dev_dbg(&intf->dev, "Ignoring descriptor: type %02x, length %ud
  ",
  					buffer[2], elength);
  			goto next_desc;
  		}
  		cnt++;
  next_desc:
  		buflen -= elength;
  		buffer += elength;
  	}
  	hdr->usb_cdc_union_desc = union_header;
  	hdr->usb_cdc_header_desc = header;
  	hdr->usb_cdc_mdlm_detail_desc = detail;
  	hdr->usb_cdc_mdlm_desc = desc;
  	hdr->usb_cdc_ether_desc = ether;
  	return cnt;
  }
  
  EXPORT_SYMBOL(cdc_parse_cdc_header);
  
  /*
   * The function can't be called inside suspend/resume callback,
   * otherwise deadlock will be caused.
   */
  int usbnet_read_cmd(struct usbnet *dev, u8 cmd, u8 reqtype,
  		    u16 value, u16 index, void *data, u16 size)
  {
  	int ret;
  
  	if (usb_autopm_get_interface(dev->intf) < 0)
  		return -ENODEV;
  	ret = __usbnet_read_cmd(dev, cmd, reqtype, value, index,
  				data, size);
  	usb_autopm_put_interface(dev->intf);
  	return ret;
  }
  EXPORT_SYMBOL_GPL(usbnet_read_cmd);
  
  /*
   * The function can't be called inside suspend/resume callback,
   * otherwise deadlock will be caused.
   */
  int usbnet_write_cmd(struct usbnet *dev, u8 cmd, u8 reqtype,
  		     u16 value, u16 index, const void *data, u16 size)
  {
  	int ret;
  
  	if (usb_autopm_get_interface(dev->intf) < 0)
  		return -ENODEV;
  	ret = __usbnet_write_cmd(dev, cmd, reqtype, value, index,
  				 data, size);
  	usb_autopm_put_interface(dev->intf);
  	return ret;
  }
  EXPORT_SYMBOL_GPL(usbnet_write_cmd);
  
  /*
   * The function can be called inside suspend/resume callback safely
   * and should only be called by suspend/resume callback generally.
   */
  int usbnet_read_cmd_nopm(struct usbnet *dev, u8 cmd, u8 reqtype,
  			  u16 value, u16 index, void *data, u16 size)
  {
  	return __usbnet_read_cmd(dev, cmd, reqtype, value, index,
  				 data, size);
  }
  EXPORT_SYMBOL_GPL(usbnet_read_cmd_nopm);
  
  /*
   * The function can be called inside suspend/resume callback safely
   * and should only be called by suspend/resume callback generally.
   */
  int usbnet_write_cmd_nopm(struct usbnet *dev, u8 cmd, u8 reqtype,
  			  u16 value, u16 index, const void *data,
  			  u16 size)
  {
  	return __usbnet_write_cmd(dev, cmd, reqtype, value, index,
  				  data, size);
  }
  EXPORT_SYMBOL_GPL(usbnet_write_cmd_nopm);
  
  static void usbnet_async_cmd_cb(struct urb *urb)
  {
  	struct usb_ctrlrequest *req = (struct usb_ctrlrequest *)urb->context;
  	int status = urb->status;
  
  	if (status < 0)
  		dev_dbg(&urb->dev->dev, "%s failed with %d",
  			__func__, status);
  
  	kfree(req);
  	usb_free_urb(urb);
  }
  
  /*
   * The caller must make sure that device can't be put into suspend
   * state until the control URB completes.
   */
  int usbnet_write_cmd_async(struct usbnet *dev, u8 cmd, u8 reqtype,
  			   u16 value, u16 index, const void *data, u16 size)
  {
  	struct usb_ctrlrequest *req = NULL;
  	struct urb *urb;
  	int err = -ENOMEM;
  	void *buf = NULL;
  
  	netdev_dbg(dev->net, "usbnet_write_cmd cmd=0x%02x reqtype=%02x"
  		   " value=0x%04x index=0x%04x size=%d
  ",
  		   cmd, reqtype, value, index, size);
  
  	urb = usb_alloc_urb(0, GFP_ATOMIC);
  	if (!urb) {
  		netdev_err(dev->net, "Error allocating URB in"
  			   " %s!
  ", __func__);
  		goto fail;
  	}
  
  	if (data) {
  		buf = kmemdup(data, size, GFP_ATOMIC);
  		if (!buf) {
  			netdev_err(dev->net, "Error allocating buffer"
  				   " in %s!
  ", __func__);
  			goto fail_free;
  		}
  	}
  
  	req = kmalloc(sizeof(struct usb_ctrlrequest), GFP_ATOMIC);
  	if (!req)
  		goto fail_free_buf;
  
  	req->bRequestType = reqtype;
  	req->bRequest = cmd;
  	req->wValue = cpu_to_le16(value);
  	req->wIndex = cpu_to_le16(index);
  	req->wLength = cpu_to_le16(size);
  
  	usb_fill_control_urb(urb, dev->udev,
  			     usb_sndctrlpipe(dev->udev, 0),
  			     (void *)req, buf, size,
  			     usbnet_async_cmd_cb, req);
  	urb->transfer_flags |= URB_FREE_BUFFER;
  
  	err = usb_submit_urb(urb, GFP_ATOMIC);
  	if (err < 0) {
  		netdev_err(dev->net, "Error submitting the control"
  			   " message: status=%d
  ", err);
  		goto fail_free;
  	}
  	return 0;
  
  fail_free_buf:
  	kfree(buf);
  fail_free:
  	kfree(req);
  	usb_free_urb(urb);
  fail:
  	return err;
  
  }
  EXPORT_SYMBOL_GPL(usbnet_write_cmd_async);
  /*-------------------------------------------------------------------------*/
  
  static int __init usbnet_init(void)
  {
  	/* Compiler should optimize this out. */
  	BUILD_BUG_ON(
  		FIELD_SIZEOF(struct sk_buff, cb) < sizeof(struct skb_data));
  
  	eth_random_addr(node_id);
  	return 0;
  }
  module_init(usbnet_init);
  
  static void __exit usbnet_exit(void)
  {
  }
  module_exit(usbnet_exit);
  
  MODULE_AUTHOR("David Brownell");
  MODULE_DESCRIPTION("USB network driver framework");
  MODULE_LICENSE("GPL");