usbnet.c

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/*
 * USB Network driver infrastructure
 * Copyright (C) 2000-2005 by David Brownell
 * Copyright (C) 2003-2005 David Hollis <[email protected]>
 *
 * 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, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

/*
 * 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).
 *
 * REVISIT qlens should be members of 'struct usbnet'; 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 RX_MAX_QUEUE_MEMORY (60 * 1518)
#define RX_QLEN(dev) (((dev)->udev->speed == USB_SPEED_HIGH) ? \
            (RX_MAX_QUEUE_MEMORY/(dev)->rx_urb_size) : 4)
#define TX_QLEN(dev) (((dev)->udev->speed == USB_SPEED_HIGH) ? \
            (RX_MAX_QUEUE_MEMORY/(dev)->hard_mtu) : 4)

// reawaken network queue this soon after stopping; else watchdog barks
#define TX_TIMEOUT_JIFFIES  (5*HZ)

// throttle rx/tx briefly after some faults, so khubd 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, i;
    unsigned char   buf [13];

    tmp = usb_string(dev->udev, iMACAddress, buf, sizeof buf);
    if (tmp != 12) {
        dev_dbg(&dev->udev->dev,
            "bad MAC string %d fetch, %d\n", iMACAddress, tmp);
        if (tmp >= 0)
            tmp = -EINVAL;
        return tmp;
    }
    for (i = tmp = 0; i < 6; i++, tmp += 2)
        dev->net->dev_addr [i] =
            (hex_to_bin(buf[tmp]) << 4) + hex_to_bin(buf[tmp + 1]);
    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;
    }

    if (!netif_running (dev->net))
        return;

    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;
}

/* 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);


/*-------------------------------------------------------------------------
 *
 * 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);
    }

    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;

    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

    if (skb->len) {
        /* all data was already cloned from skb inside the driver */
        if (dev->driver_info->flags & FLAG_MULTI_PACKET)
            dev_kfree_skb_any(skb);
        else
            usbnet_skb_return(dev, skb);
        return;
    }

    netif_dbg(dev, rx_err, dev->net, "drop\n");
    dev->net->stats.rx_errors++;
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:
        if (skb->len < dev->net->hard_header_len) {
            state = rx_cleanup;
            dev->net->stats.rx_errors++;
            dev->net->stats.rx_length_errors++;
            netif_dbg(dev, rx_err, dev->net,
                  "rx length %d\n", skb->len);
        }
        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 khubd disconnect() delays.
     * throttle down resubmits, to avoid log floods; just temporarily,
     * so we still recover when the fault isn't a khubd 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;
    }

    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_WAIT_QUEUE_HEAD_ONSTACK(unlink_wakeup);
    DECLARE_WAITQUEUE(wait, current);
    int temp;

    /* ensure there are no more active urbs */
    add_wait_queue(&unlink_wakeup, &wait);
    set_current_state(TASK_UNINTERRUPTIBLE);
    dev->wait = &unlink_wakeup;
    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);
    dev->wait = NULL;
    remove_wait_queue(&unlink_wakeup, &wait);
}

int usbnet_stop (struct net_device *net)
{
    struct usbnet       *dev = netdev_priv(net);
    struct driver_info  *info = dev->driver_info;
    int         retval;

    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);

    /* 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);

    usb_kill_urb(dev->interrupt);

    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 (info->manage_power)
        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;
    }

    // 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 = usb_submit_urb (dev->interrupt, 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");

    // 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)
            goto done_manage_power_error;
        usb_autopm_put_interface(dev->intf);
    }
    return retval;

done_manage_power_error:
    clear_bit(EVENT_DEV_OPEN, &dev->flags);
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);

    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,
};

/*-------------------------------------------------------------------------*/

/* 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
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);
        }
    }

    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) {
        if (!(dev->driver_info->flags & FLAG_MULTI_PACKET))
            dev->net->stats.tx_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 khubd 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);

    // FIXME: device recovery -- reset?
}
EXPORT_SYMBOL_GPL(usbnet_tx_timeout);

/*-------------------------------------------------------------------------*/

netdev_tx_t usbnet_start_xmit (struct sk_buff *skb,
                     struct net_device *net)
{
    struct usbnet       *dev = netdev_priv(net);
    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) {
            if (netif_msg_tx_err(dev)) {
                netif_dbg(dev, tx_err, dev->net, "can't tx_fixup skb\n");
                goto drop;
            } else {
                /* cdc_ncm collected packet; waits for more */
                goto not_drop;
            }
        }
    }
    length = skb->len;

    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;
    entry->length = length;

    usb_fill_bulk_urb (urb, dev->udev, dev->out,
            skb->data, skb->len, tx_complete, skb);

    /* 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)) {
                urb->transfer_buffer_length++;
                if (skb_tailroom(skb)) {
                    skb->data[skb->len] = 0;
                    __skb_put(skb, 1);
                }
            }
        } else
            urb->transfer_flags |= URB_ZERO_PACKET;
    }

    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);
        usb_free_urb (urb);
    } else
        netif_dbg(dev, tx_queued, dev->net,
              "> tx, len %d, 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:
        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);
        }
    }

    // waiting for all pending urbs to complete?
    if (dev->wait) {
        if ((dev->txq.qlen + dev->rxq.qlen + dev->done.qlen) == 0) {
            wake_up (dev->wait);
        }

    // or are we maybe short a few urbs?
    } else if (netif_running (dev->net) &&
           netif_device_present (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);

    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_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 USB_SUSPEND(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);
    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, 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);

    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");

        /* 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);

    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);

    status = register_netdev (net);
    if (status)
        goto out4;
    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)
        netif_carrier_off(net);

    return 0;

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);
        usb_kill_urb(dev->interrupt);

        /*
         * 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 URBs */
        if (dev->interrupt && test_bit(EVENT_DEV_OPEN, &dev->flags))
            usb_submit_urb(dev->interrupt, 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);
                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 */
            if (!dev->wait &&
                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);

/*-------------------------------------------------------------------------*/

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");