Add the rt linux 4.1.3-rt3 as base
[kvmfornfv.git] / kernel / drivers / net / usb / usbnet.c
diff --git a/kernel/drivers/net/usb/usbnet.c b/kernel/drivers/net/usb/usbnet.c
new file mode 100644 (file)
index 0000000..3c86b10
--- /dev/null
@@ -0,0 +1,2107 @@
+/*
+ * 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/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\n", 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\n", status);
+               return;
+
+       /* NOTE:  not throttling like RX/TX, since this endpoint
+        * already polls infrequently
+        */
+       default:
+               netdev_dbg(dev->net, "intr status %d\n", status);
+               break;
+       }
+
+       status = usb_submit_urb (urb, GFP_ATOMIC);
+       if (status != 0)
+               netif_err(dev, timer, dev->net,
+                         "intr resubmit --> %d\n", 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\n",
+                               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\n",
+                       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\n");
+       }
+       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\n",
+                       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\n");
+               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\n",
+                 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\n", 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);
+
+\f
+/*-------------------------------------------------------------------------
+ *
+ * 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);
+       spin_unlock(&list->lock);
+       spin_lock(&dev->done.lock);
+       __skb_queue_tail(&dev->done, skb);
+       if (dev->done.qlen == 1)
+               tasklet_schedule(&dev->bh);
+       spin_unlock_irqrestore(&dev->done.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\n", work);
+       } else {
+               netdev_dbg(dev->net, "kevent %d scheduled\n", 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\n");
+               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\n");
+                       netif_device_detach (dev->net);
+                       break;
+               case -EHOSTUNREACH:
+                       retval = -ENOLINK;
+                       break;
+               default:
+                       netif_dbg(dev, rx_err, dev->net,
+                                 "rx submit, %d\n", 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\n");
+               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\n", 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\n", 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\n", 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\n", 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\n");
+}
+
+/*-------------------------------------------------------------------------*/
+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\n");
+}
+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\n", 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\n", 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);
+
+/*-------------------------------------------------------------------------*/
+
+// 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. */
+       while (!skb_queue_empty(&dev->rxq)
+               && !skb_queue_empty(&dev->txq)
+               && !skb_queue_empty(&dev->done)) {
+                       schedule_timeout(msecs_to_jiffies(UNLINK_TIMEOUT_MS));
+                       set_current_state(TASK_UNINTERRUPTIBLE);
+                       netif_dbg(dev, ifdown, dev->net,
+                                 "waited for %d urb completions\n", 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;
+
+       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\n",
+                  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\n",
+                                  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);
+
+       /* 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 &&
+           !test_and_clear_bit(EVENT_NO_RUNTIME_PM, &dev->flags))
+               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\n",
+                          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\n",
+                          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\n", 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\n", 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\n",
+                  (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\n",
+                                          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\n",
+                                          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\n",
+                                   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\n", 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\n", urb->status);
+                       }
+                       netif_stop_queue (dev->net);
+                       break;
+               default:
+                       netif_dbg(dev, tx_err, dev->net,
+                                 "tx err %d\n", 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\n");
+                       goto drop;
+               }
+       }
+
+       if (!(urb = usb_alloc_urb (0, GFP_ATOMIC))) {
+               netif_dbg(dev, tx_err, dev->net, "no urb\n");
+               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\n");
+               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\n", 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\n", 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\n", 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\n", 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\n",
+                                         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\n",
+                  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\n", 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;
+#if 0
+// dma_supported() is deeply broken on almost all architectures
+       // possible with some EHCI controllers
+       if (dma_supported (&udev->dev, DMA_BIT_MASK(64)))
+               net->features |= NETIF_F_HIGHDMA;
+#endif
+
+       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\n",
+                  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:
+       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\n",
+                  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\n",
+                  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;
+}
+
+/*
+ * 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\n",
+                  cmd, reqtype, value, index, size);
+
+       urb = usb_alloc_urb(0, GFP_ATOMIC);
+       if (!urb) {
+               netdev_err(dev->net, "Error allocating URB in"
+                          " %s!\n", __func__);
+               goto fail;
+       }
+
+       if (data) {
+               buf = kmemdup(data, size, GFP_ATOMIC);
+               if (!buf) {
+                       netdev_err(dev->net, "Error allocating buffer"
+                                  " in %s!\n", __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\n", 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");