解决“ipheth_tx_timeout: TX timeout”

在调试iOS的usb tethering时发现这个问题的。（如何搭建iOS的usb tethering请看我的这篇文章《OpenWrt支持usb tethering》）

其实当前主流Linux（如Ubuntu）使用的Diego Giagio作者的ipheth，功能性是好的，但稳定性不足。
废话少说

code：

<基于kernel 3.3.8>
linux-3.3.8/drivers/net/usb/ipheth.c

/*
 * Copyright (C) 2017 Walker Wei<walker0411@163.com>. All rights reserved.
 * Copyright (C) 2009 Diego Giagio. All rights reserved.
 * Copyright (C) 2000-2005 by David Brownell
 * Copyright (C) 2003-2005 David Hollis <dhollis@davehollis.com>
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

/*
 * Thanks to Diego Giagio for figuring out the programming details for
 * the Apple iPhone Ethernet driver.
 * This program is based on usbnet which is written by David Brownell.
 */

#include <linux/module.h>
#include <linux/init.h>
#include <linux/netdevice.h>
#include <linux/etherdevice.h>
#include <linux/ethtool.h>
#include <linux/workqueue.h>
#include <linux/slab.h>
#include <linux/mii.h>
#include <linux/usb.h>
#include <linux/usb/cdc.h>
#include <linux/usb/usbnet.h>

#define USB_VENDOR_APPLE        0x05ac
#define USB_PRODUCT_IPHONE      0x1290
#define USB_PRODUCT_IPHONE_3G   0x1292
#define USB_PRODUCT_IPHONE_3GS  0x1294
#define USB_PRODUCT_IPHONE_4    0x1297
#define USB_PRODUCT_IPHONE_4_VZW 0x129c
#define USB_PRODUCT_IPHONE_4S   0x12a0
#define USB_PRODUCT_IPHONE_5   0x12a8
#define USB_PRODUCT_IPAD       0x129a
#define USB_PRODUCT_IPAD_MINI  0x12ab

#define IPHETH_USBINTF_CLASS    255
#define IPHETH_USBINTF_SUBCLASS 253
#define IPHETH_USBINTF_PROTO    1

#define IPHETH_INTFNUM          2
#define IPHETH_ALT_INTFNUM      1

#define IPHETH_BUF_SIZE         1516
#define IPHETH_IP_ALIGN         2      /* padding at front of URB */

#define IPHETH_CTRL_ENDP        0x00
#define IPHETH_CTRL_BUF_SIZE    0x40
#define IPHETH_CTRL_TIMEOUT     (5 * HZ)

#define IPHETH_CMD_GET_MACADDR   0x00
#define IPHETH_CMD_CARRIER_CHECK 0x45

#define IPHETH_CARRIER_CHECK_TIMEOUT round_jiffies_relative(1 * HZ)
#define IPHETH_CARRIER_ON       0x04

static struct ipheth_local local;

struct ipheth_local {
    struct usbnet *dev;
    struct mutex local_mutex;
    struct delayed_work carrier_work;
};

/* same as usbnet_netdev_ops but MTU change not allowed */
static const struct net_device_ops ipheth_netdev_ops = {
    .ndo_open       = usbnet_open,
    .ndo_stop       = usbnet_stop,
    .ndo_start_xmit     = usbnet_start_xmit,
    .ndo_tx_timeout     = usbnet_tx_timeout,
    .ndo_set_mac_address    = eth_mac_addr,
    .ndo_validate_addr  = eth_validate_addr,
};

void ipheth_status(struct usbnet *dev, struct urb *urb)
{
    netdev_dbg(dev->net, "ipheth status urb, len %d stat %d\n",
            urb->actual_length, urb->status);
}
EXPORT_SYMBOL_GPL(ipheth_status);

static int ipheth_carrier_set(struct usbnet *dev)
{
    struct usb_device *udev = NULL;
    int retval = 0;
    unsigned char ctrl_buf[IPHETH_CTRL_BUF_SIZE] = {0};

    if (NULL == dev)
    {
        err("%s: struct usbnet *dev is NULL.", __func__);
        retval = -EINVAL;
        return retval;
    }

    udev = dev->udev;
    retval = usb_control_msg(udev,
            usb_rcvctrlpipe(udev, IPHETH_CTRL_ENDP),
            IPHETH_CMD_CARRIER_CHECK, /* request */
            0xc0, /* request type */
            0x00, /* value */
            0x02, /* index */
            (void *)ctrl_buf,
            IPHETH_CTRL_BUF_SIZE,
            IPHETH_CTRL_TIMEOUT);
    if (retval < 0) {
        err("%s: usb_control_msg: %d", __func__, retval);
    }
    else
    {
        if (ctrl_buf[0] == IPHETH_CARRIER_ON)
            netif_carrier_on(dev->net);
        else
            netif_carrier_off(dev->net);
    }

    return retval;
}

static void ipheth_carrier_check_work(struct work_struct *work)
{
    struct usbnet *dev = NULL;

    mutex_lock(&(local.local_mutex));
    dev = local.dev;
    ipheth_carrier_set(dev);
    schedule_delayed_work(&(local.carrier_work), IPHETH_CARRIER_CHECK_TIMEOUT);
    mutex_unlock(&(local.local_mutex));
}

static int ipheth_get_macaddr(struct usbnet *dev)
{
    struct usb_device *udev = dev->udev;
    struct net_device *net = dev->net;
    int retval;
    unsigned char ctrl_buf[IPHETH_CTRL_BUF_SIZE] = {0};

    retval = usb_control_msg(udev,
                 usb_rcvctrlpipe(udev, IPHETH_CTRL_ENDP),
                 IPHETH_CMD_GET_MACADDR, /* request */
                 0xc0, /* request type */
                 0x00, /* value */
                 0x02, /* index */
                 (void *)ctrl_buf,
                 IPHETH_CTRL_BUF_SIZE,
                 IPHETH_CTRL_TIMEOUT);
    if (retval < 0) {
        err("%s: usb_control_msg: %d", __func__, retval);
    } else if (retval < ETH_ALEN) {
        err("%s: usb_control_msg: short packet: %d bytes",
            __func__, retval);
        retval = -EINVAL;
    } else {
        memcpy(net->dev_addr, (const void *)ctrl_buf, ETH_ALEN);
        memcpy(net->perm_addr, (const void *)ctrl_buf, ETH_ALEN);
        retval = 0;
    }

    return retval;
}

static int ipheth_bind(struct usbnet *dev, struct usb_interface *intf)
{
    int retval = 0;//success
    int i = 0;
    struct usb_host_interface *hintf;
    struct usb_endpoint_descriptor *endp;
    u8 bulk_in = 0;
    u8 bulk_out = 0;

    /* Set up endpoints */
    hintf = usb_altnum_to_altsetting(intf, IPHETH_ALT_INTFNUM);
    if (hintf == NULL) {
        retval = -ENODEV;
        err("Unable to find alternate settings interface, retval=%d", retval);
        return retval;
    }

    for (i = 0; i < hintf->desc.bNumEndpoints; i++) {
        endp = &hintf->endpoint[i].desc;
        if (usb_endpoint_is_bulk_in(endp))
            bulk_in = endp->bEndpointAddress;
        else if (usb_endpoint_is_bulk_out(endp))
            bulk_out = endp->bEndpointAddress;
    }

    if (!(bulk_in && bulk_out)) {
        retval = -ENODEV;
        err("Unable to find endpoints, retval=%d", retval);
        return retval;
    }
    else
    {
        dev->in = usb_rcvbulkpipe(dev->udev, bulk_in & USB_ENDPOINT_NUMBER_MASK);
        dev->out= usb_sndbulkpipe(dev->udev, bulk_out & USB_ENDPOINT_NUMBER_MASK);
    }

    //fix bulk recv buffer size
    dev->rx_urb_size = IPHETH_BUF_SIZE;
    //dev->hard_mtu = IPHETH_BUF_SIZE;//need this?

    //get hardware addr
    retval = ipheth_get_macaddr(dev);
    if (0 != retval)
    {
        err("Unable to get macaddr, retval=%d", retval);
        return retval;
    }

    //carrier check:check the remote tethering enable or not.
    mutex_init (&(local.local_mutex));
    INIT_DELAYED_WORK(&(local.carrier_work), ipheth_carrier_check_work);
    local.dev = dev;

    return retval;
}
EXPORT_SYMBOL_GPL(ipheth_bind);

static int ipheth_reset(struct usbnet *dev)
{
    int retval = 0;//success
    struct work_struct *work = NULL;

    //Attention: this func's section should not be in "reset" function,
    //I put it here because it still need to be called during the usbnet_open().
    usb_set_interface(dev->udev, IPHETH_INTFNUM, IPHETH_ALT_INTFNUM);
    ipheth_carrier_check_work(work);

    return retval;
}
EXPORT_SYMBOL_GPL(ipheth_reset);

static int ipheth_stop(struct usbnet *dev)
{
    mutex_lock(&(local.local_mutex));
    cancel_delayed_work_sync(&local.carrier_work);
    mutex_unlock(&(local.local_mutex));

    return 0;
}
EXPORT_SYMBOL_GPL(ipheth_stop);

int ipheth_rx_fixup(struct usbnet *dev, struct sk_buff *skb)
{
    skb_pull(skb, IPHETH_IP_ALIGN);
    return 1;
}
EXPORT_SYMBOL_GPL(ipheth_rx_fixup);

static const struct driver_info ipheth_info = {
    .description =  "ipheth device",
    .flags =    FLAG_ETHER | FLAG_NO_SETINT,
    .status =   ipheth_status,
    .bind =     ipheth_bind,
    .reset =    ipheth_reset,
    .stop =     ipheth_stop,
    .rx_fixup = ipheth_rx_fixup,
};

/*-------------------------------------------------------------------------*/
static struct usb_device_id ipheth_table[] = {
    { USB_DEVICE_AND_INTERFACE_INFO(
        USB_VENDOR_APPLE, USB_PRODUCT_IPHONE,
        IPHETH_USBINTF_CLASS, IPHETH_USBINTF_SUBCLASS,
        IPHETH_USBINTF_PROTO),
        .driver_info = (unsigned long) &ipheth_info,},
    { USB_DEVICE_AND_INTERFACE_INFO(
        USB_VENDOR_APPLE, USB_PRODUCT_IPHONE_3G,
        IPHETH_USBINTF_CLASS, IPHETH_USBINTF_SUBCLASS,
        IPHETH_USBINTF_PROTO),
        .driver_info = (unsigned long) &ipheth_info,},
    { USB_DEVICE_AND_INTERFACE_INFO(
        USB_VENDOR_APPLE, USB_PRODUCT_IPHONE_3GS,
        IPHETH_USBINTF_CLASS, IPHETH_USBINTF_SUBCLASS,
        IPHETH_USBINTF_PROTO),
        .driver_info = (unsigned long) &ipheth_info,},
    { USB_DEVICE_AND_INTERFACE_INFO(
        USB_VENDOR_APPLE, USB_PRODUCT_IPHONE_4,
        IPHETH_USBINTF_CLASS, IPHETH_USBINTF_SUBCLASS,
        IPHETH_USBINTF_PROTO),
        .driver_info = (unsigned long) &ipheth_info,},
    { USB_DEVICE_AND_INTERFACE_INFO(
        USB_VENDOR_APPLE, USB_PRODUCT_IPHONE_4_VZW,
        IPHETH_USBINTF_CLASS, IPHETH_USBINTF_SUBCLASS,
        IPHETH_USBINTF_PROTO),
        .driver_info = (unsigned long) &ipheth_info,},
    { USB_DEVICE_AND_INTERFACE_INFO(
        USB_VENDOR_APPLE, USB_PRODUCT_IPHONE_4S,
        IPHETH_USBINTF_CLASS, IPHETH_USBINTF_SUBCLASS,
        IPHETH_USBINTF_PROTO),
        .driver_info = (unsigned long) &ipheth_info,},
    { USB_DEVICE_AND_INTERFACE_INFO(
        USB_VENDOR_APPLE, USB_PRODUCT_IPAD,
        IPHETH_USBINTF_CLASS, IPHETH_USBINTF_SUBCLASS,
        IPHETH_USBINTF_PROTO),
        .driver_info = (unsigned long) &ipheth_info,},
    { USB_DEVICE_AND_INTERFACE_INFO(
        USB_VENDOR_APPLE, USB_PRODUCT_IPAD_MINI,
        IPHETH_USBINTF_CLASS, IPHETH_USBINTF_SUBCLASS,
        IPHETH_USBINTF_PROTO),
        .driver_info = (unsigned long) &ipheth_info,},
    { USB_DEVICE_AND_INTERFACE_INFO(
        USB_VENDOR_APPLE, USB_PRODUCT_IPHONE_5,
        IPHETH_USBINTF_CLASS, IPHETH_USBINTF_SUBCLASS,
        IPHETH_USBINTF_PROTO),
        .driver_info = (unsigned long) &ipheth_info,},
    { }
};
MODULE_DEVICE_TABLE(usb, ipheth_table);

static struct usb_driver ipheth_driver = {
    .name =     "ipheth",
    .id_table = ipheth_table,
    .probe =    usbnet_probe,
    .disconnect =   usbnet_disconnect,
    .suspend =  usbnet_suspend,
    .resume =   usbnet_resume,
};
module_usb_driver(ipheth_driver);

MODULE_AUTHOR("Walker Wei");
MODULE_DESCRIPTION("Apple iPhone USB Ethernet driver");
MODULE_LICENSE("GPL");

思路

android使用的usb tethering是基于Rndis的，一个Microsoft提出的usb tethering协议，它的结构是Rndis协议层+usb net，而usb net正是一个封装了USB networking的架构，将usb设备虚拟成Ethernet adapters。
usb net应该比较稳定了，因为不但Rndis使用，其他的一些usb net adapter产品，如亚信的AX88179、AX88772B等也都是基于usb net来做。
因此，本次的修改就是将原有的ipheth移植到usb net上，变成ipheth+usb net的形势，经测试，稳定多了，尤其是大量数据传输的时候。

当前的code只是测试版本，还有很多优化的空间，后续再更新。