message.c

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/*
 * message.c - synchronous message handling
 */

#include <linux/pci.h>  /* for scatterlist macros */
#include <linux/usb.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/init.h>
#include <linux/mm.h>
#include <linux/timer.h>
#include <linux/ctype.h>
#include <linux/nls.h>
#include <linux/device.h>
#include <linux/scatterlist.h>
#include <linux/usb/quirks.h>
#include <linux/usb/hcd.h>  /* for usbcore internals */
#include <asm/byteorder.h>

#include "usb.h"

static void cancel_async_set_config(struct usb_device *udev);

struct api_context {
    struct completion   done;
    int         status;
};

static void usb_api_blocking_completion(struct urb *urb)
{
    struct api_context *ctx = urb->context;

    ctx->status = urb->status;
    complete(&ctx->done);
}


/*
 * Starts urb and waits for completion or timeout. Note that this call
 * is NOT interruptible. Many device driver i/o requests should be
 * interruptible and therefore these drivers should implement their
 * own interruptible routines.
 */
static int usb_start_wait_urb(struct urb *urb, int timeout, int *actual_length)
{
    struct api_context ctx;
    unsigned long expire;
    int retval;

    init_completion(&ctx.done);
    urb->context = &ctx;
    urb->actual_length = 0;
    retval = usb_submit_urb(urb, GFP_NOIO);
    if (unlikely(retval))
        goto out;

    expire = timeout ? msecs_to_jiffies(timeout) : MAX_SCHEDULE_TIMEOUT;
    if (!wait_for_completion_timeout(&ctx.done, expire)) {
        usb_kill_urb(urb);
        retval = (ctx.status == -ENOENT ? -ETIMEDOUT : ctx.status);

        dev_dbg(&urb->dev->dev,
            "%s timed out on ep%d%s len=%u/%u\n",
            current->comm,
            usb_endpoint_num(&urb->ep->desc),
            usb_urb_dir_in(urb) ? "in" : "out",
            urb->actual_length,
            urb->transfer_buffer_length);
    } else
        retval = ctx.status;
out:
    if (actual_length)
        *actual_length = urb->actual_length;

    usb_free_urb(urb);
    return retval;
}

/*-------------------------------------------------------------------*/
/* returns status (negative) or length (positive) */
static int usb_internal_control_msg(struct usb_device *usb_dev,
                    unsigned int pipe,
                    struct usb_ctrlrequest *cmd,
                    void *data, int len, int timeout)
{
    struct urb *urb;
    int retv;
    int length;

    urb = usb_alloc_urb(0, GFP_NOIO);
    if (!urb)
        return -ENOMEM;

    usb_fill_control_urb(urb, usb_dev, pipe, (unsigned char *)cmd, data,
                 len, usb_api_blocking_completion, NULL);

    retv = usb_start_wait_urb(urb, timeout, &length);
    if (retv < 0)
        return retv;
    else
        return length;
}

int usb_control_msg(struct usb_device *dev, unsigned int pipe, __u8 request,
            __u8 requesttype, __u16 value, __u16 index, void *data,
            __u16 size, int timeout)
{
    struct usb_ctrlrequest *dr;
    int ret;

    dr = kmalloc(sizeof(struct usb_ctrlrequest), GFP_NOIO);
    if (!dr)
        return -ENOMEM;

    dr->bRequestType = requesttype;
    dr->bRequest = request;
    dr->wValue = cpu_to_le16(value);
    dr->wIndex = cpu_to_le16(index);
    dr->wLength = cpu_to_le16(size);

    ret = usb_internal_control_msg(dev, pipe, dr, data, size, timeout);

    kfree(dr);

    return ret;
}
EXPORT_SYMBOL_GPL(usb_control_msg);

int usb_interrupt_msg(struct usb_device *usb_dev, unsigned int pipe,
              void *data, int len, int *actual_length, int timeout)
{
    return usb_bulk_msg(usb_dev, pipe, data, len, actual_length, timeout);
}
EXPORT_SYMBOL_GPL(usb_interrupt_msg);

int usb_bulk_msg(struct usb_device *usb_dev, unsigned int pipe,
         void *data, int len, int *actual_length, int timeout)
{
    struct urb *urb;
    struct usb_host_endpoint *ep;

    ep = usb_pipe_endpoint(usb_dev, pipe);
    if (!ep || len < 0)
        return -EINVAL;

    urb = usb_alloc_urb(0, GFP_KERNEL);
    if (!urb)
        return -ENOMEM;

    if ((ep->desc.bmAttributes & USB_ENDPOINT_XFERTYPE_MASK) ==
            USB_ENDPOINT_XFER_INT) {
        pipe = (pipe & ~(3 << 30)) | (PIPE_INTERRUPT << 30);
        usb_fill_int_urb(urb, usb_dev, pipe, data, len,
                usb_api_blocking_completion, NULL,
                ep->desc.bInterval);
    } else
        usb_fill_bulk_urb(urb, usb_dev, pipe, data, len,
                usb_api_blocking_completion, NULL);

    return usb_start_wait_urb(urb, timeout, actual_length);
}
EXPORT_SYMBOL_GPL(usb_bulk_msg);

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

static void sg_clean(struct usb_sg_request *io)
{
    if (io->urbs) {
        while (io->entries--)
            usb_free_urb(io->urbs [io->entries]);
        kfree(io->urbs);
        io->urbs = NULL;
    }
    io->dev = NULL;
}

static void sg_complete(struct urb *urb)
{
    struct usb_sg_request *io = urb->context;
    int status = urb->status;

    spin_lock(&io->lock);

    /* In 2.5 we require hcds' endpoint queues not to progress after fault
     * reports, until the completion callback (this!) returns.  That lets
     * device driver code (like this routine) unlink queued urbs first,
     * if it needs to, since the HC won't work on them at all.  So it's
     * not possible for page N+1 to overwrite page N, and so on.
     *
     * That's only for "hard" faults; "soft" faults (unlinks) sometimes
     * complete before the HCD can get requests away from hardware,
     * though never during cleanup after a hard fault.
     */
    if (io->status
            && (io->status != -ECONNRESET
                || status != -ECONNRESET)
            && urb->actual_length) {
        dev_err(io->dev->bus->controller,
            "dev %s ep%d%s scatterlist error %d/%d\n",
            io->dev->devpath,
            usb_endpoint_num(&urb->ep->desc),
            usb_urb_dir_in(urb) ? "in" : "out",
            status, io->status);
        /* BUG (); */
    }

    if (io->status == 0 && status && status != -ECONNRESET) {
        int i, found, retval;

        io->status = status;

        /* the previous urbs, and this one, completed already.
         * unlink pending urbs so they won't rx/tx bad data.
         * careful: unlink can sometimes be synchronous...
         */
        spin_unlock(&io->lock);
        for (i = 0, found = 0; i < io->entries; i++) {
            if (!io->urbs [i] || !io->urbs [i]->dev)
                continue;
            if (found) {
                retval = usb_unlink_urb(io->urbs [i]);
                if (retval != -EINPROGRESS &&
                    retval != -ENODEV &&
                    retval != -EBUSY &&
                    retval != -EIDRM)
                    dev_err(&io->dev->dev,
                        "%s, unlink --> %d\n",
                        __func__, retval);
            } else if (urb == io->urbs [i])
                found = 1;
        }
        spin_lock(&io->lock);
    }

    /* on the last completion, signal usb_sg_wait() */
    io->bytes += urb->actual_length;
    io->count--;
    if (!io->count)
        complete(&io->complete);

    spin_unlock(&io->lock);
}


int usb_sg_init(struct usb_sg_request *io, struct usb_device *dev,
        unsigned pipe, unsigned period, struct scatterlist *sg,
        int nents, size_t length, gfp_t mem_flags)
{
    int i;
    int urb_flags;
    int use_sg;

    if (!io || !dev || !sg
            || usb_pipecontrol(pipe)
            || usb_pipeisoc(pipe)
            || nents <= 0)
        return -EINVAL;

    spin_lock_init(&io->lock);
    io->dev = dev;
    io->pipe = pipe;

    if (dev->bus->sg_tablesize > 0) {
        use_sg = true;
        io->entries = 1;
    } else {
        use_sg = false;
        io->entries = nents;
    }

    /* initialize all the urbs we'll use */
    io->urbs = kmalloc(io->entries * sizeof *io->urbs, mem_flags);
    if (!io->urbs)
        goto nomem;

    urb_flags = URB_NO_INTERRUPT;
    if (usb_pipein(pipe))
        urb_flags |= URB_SHORT_NOT_OK;

    for_each_sg(sg, sg, io->entries, i) {
        struct urb *urb;
        unsigned len;

        urb = usb_alloc_urb(0, mem_flags);
        if (!urb) {
            io->entries = i;
            goto nomem;
        }
        io->urbs[i] = urb;

        urb->dev = NULL;
        urb->pipe = pipe;
        urb->interval = period;
        urb->transfer_flags = urb_flags;
        urb->complete = sg_complete;
        urb->context = io;
        urb->sg = sg;

        if (use_sg) {
            /* There is no single transfer buffer */
            urb->transfer_buffer = NULL;
            urb->num_sgs = nents;

            /* A length of zero means transfer the whole sg list */
            len = length;
            if (len == 0) {
                struct scatterlist  *sg2;
                int         j;

                for_each_sg(sg, sg2, nents, j)
                    len += sg2->length;
            }
        } else {
            /*
             * Some systems can't use DMA; they use PIO instead.
             * For their sakes, transfer_buffer is set whenever
             * possible.
             */
            if (!PageHighMem(sg_page(sg)))
                urb->transfer_buffer = sg_virt(sg);
            else
                urb->transfer_buffer = NULL;

            len = sg->length;
            if (length) {
                len = min_t(size_t, len, length);
                length -= len;
                if (length == 0)
                    io->entries = i + 1;
            }
        }
        urb->transfer_buffer_length = len;
    }
    io->urbs[--i]->transfer_flags &= ~URB_NO_INTERRUPT;

    /* transaction state */
    io->count = io->entries;
    io->status = 0;
    io->bytes = 0;
    init_completion(&io->complete);
    return 0;

nomem:
    sg_clean(io);
    return -ENOMEM;
}
EXPORT_SYMBOL_GPL(usb_sg_init);

void usb_sg_wait(struct usb_sg_request *io)
{
    int i;
    int entries = io->entries;

    /* queue the urbs.  */
    spin_lock_irq(&io->lock);
    i = 0;
    while (i < entries && !io->status) {
        int retval;

        io->urbs[i]->dev = io->dev;
        retval = usb_submit_urb(io->urbs [i], GFP_ATOMIC);

        /* after we submit, let completions or cancelations fire;
         * we handshake using io->status.
         */
        spin_unlock_irq(&io->lock);
        switch (retval) {
            /* maybe we retrying will recover */
        case -ENXIO:    /* hc didn't queue this one */
        case -EAGAIN:
        case -ENOMEM:
            retval = 0;
            yield();
            break;

            /* no error? continue immediately.
             *
             * NOTE: to work better with UHCI (4K I/O buffer may
             * need 3K of TDs) it may be good to limit how many
             * URBs are queued at once; N milliseconds?
             */
        case 0:
            ++i;
            cpu_relax();
            break;

            /* fail any uncompleted urbs */
        default:
            io->urbs[i]->status = retval;
            dev_dbg(&io->dev->dev, "%s, submit --> %d\n",
                __func__, retval);
            usb_sg_cancel(io);
        }
        spin_lock_irq(&io->lock);
        if (retval && (io->status == 0 || io->status == -ECONNRESET))
            io->status = retval;
    }
    io->count -= entries - i;
    if (io->count == 0)
        complete(&io->complete);
    spin_unlock_irq(&io->lock);

    /* OK, yes, this could be packaged as non-blocking.
     * So could the submit loop above ... but it's easier to
     * solve neither problem than to solve both!
     */
    wait_for_completion(&io->complete);

    sg_clean(io);
}
EXPORT_SYMBOL_GPL(usb_sg_wait);

void usb_sg_cancel(struct usb_sg_request *io)
{
    unsigned long flags;

    spin_lock_irqsave(&io->lock, flags);

    /* shut everything down, if it didn't already */
    if (!io->status) {
        int i;

        io->status = -ECONNRESET;
        spin_unlock(&io->lock);
        for (i = 0; i < io->entries; i++) {
            int retval;

            if (!io->urbs [i]->dev)
                continue;
            retval = usb_unlink_urb(io->urbs [i]);
            if (retval != -EINPROGRESS
                    && retval != -ENODEV
                    && retval != -EBUSY
                    && retval != -EIDRM)
                dev_warn(&io->dev->dev, "%s, unlink --> %d\n",
                    __func__, retval);
        }
        spin_lock(&io->lock);
    }
    spin_unlock_irqrestore(&io->lock, flags);
}
EXPORT_SYMBOL_GPL(usb_sg_cancel);

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

int usb_get_descriptor(struct usb_device *dev, unsigned char type,
               unsigned char index, void *buf, int size)
{
    int i;
    int result;

    memset(buf, 0, size);   /* Make sure we parse really received data */

    for (i = 0; i < 3; ++i) {
        /* retry on length 0 or error; some devices are flakey */
        result = usb_control_msg(dev, usb_rcvctrlpipe(dev, 0),
                USB_REQ_GET_DESCRIPTOR, USB_DIR_IN,
                (type << 8) + index, 0, buf, size,
                USB_CTRL_GET_TIMEOUT);
        if (result <= 0 && result != -ETIMEDOUT)
            continue;
        if (result > 1 && ((u8 *)buf)[1] != type) {
            result = -ENODATA;
            continue;
        }
        break;
    }
    return result;
}
EXPORT_SYMBOL_GPL(usb_get_descriptor);

static int usb_get_string(struct usb_device *dev, unsigned short langid,
              unsigned char index, void *buf, int size)
{
    int i;
    int result;

    for (i = 0; i < 3; ++i) {
        /* retry on length 0 or stall; some devices are flakey */
        result = usb_control_msg(dev, usb_rcvctrlpipe(dev, 0),
            USB_REQ_GET_DESCRIPTOR, USB_DIR_IN,
            (USB_DT_STRING << 8) + index, langid, buf, size,
            USB_CTRL_GET_TIMEOUT);
        if (result == 0 || result == -EPIPE)
            continue;
        if (result > 1 && ((u8 *) buf)[1] != USB_DT_STRING) {
            result = -ENODATA;
            continue;
        }
        break;
    }
    return result;
}

static void usb_try_string_workarounds(unsigned char *buf, int *length)
{
    int newlength, oldlength = *length;

    for (newlength = 2; newlength + 1 < oldlength; newlength += 2)
        if (!isprint(buf[newlength]) || buf[newlength + 1])
            break;

    if (newlength > 2) {
        buf[0] = newlength;
        *length = newlength;
    }
}

static int usb_string_sub(struct usb_device *dev, unsigned int langid,
              unsigned int index, unsigned char *buf)
{
    int rc;

    /* Try to read the string descriptor by asking for the maximum
     * possible number of bytes */
    if (dev->quirks & USB_QUIRK_STRING_FETCH_255)
        rc = -EIO;
    else
        rc = usb_get_string(dev, langid, index, buf, 255);

    /* If that failed try to read the descriptor length, then
     * ask for just that many bytes */
    if (rc < 2) {
        rc = usb_get_string(dev, langid, index, buf, 2);
        if (rc == 2)
            rc = usb_get_string(dev, langid, index, buf, buf[0]);
    }

    if (rc >= 2) {
        if (!buf[0] && !buf[1])
            usb_try_string_workarounds(buf, &rc);

        /* There might be extra junk at the end of the descriptor */
        if (buf[0] < rc)
            rc = buf[0];

        rc = rc - (rc & 1); /* force a multiple of two */
    }

    if (rc < 2)
        rc = (rc < 0 ? rc : -EINVAL);

    return rc;
}

static int usb_get_langid(struct usb_device *dev, unsigned char *tbuf)
{
    int err;

    if (dev->have_langid)
        return 0;

    if (dev->string_langid < 0)
        return -EPIPE;

    err = usb_string_sub(dev, 0, 0, tbuf);

    /* If the string was reported but is malformed, default to english
     * (0x0409) */
    if (err == -ENODATA || (err > 0 && err < 4)) {
        dev->string_langid = 0x0409;
        dev->have_langid = 1;
        dev_err(&dev->dev,
            "string descriptor 0 malformed (err = %d), "
            "defaulting to 0x%04x\n",
                err, dev->string_langid);
        return 0;
    }

    /* In case of all other errors, we assume the device is not able to
     * deal with strings at all. Set string_langid to -1 in order to
     * prevent any string to be retrieved from the device */
    if (err < 0) {
        dev_err(&dev->dev, "string descriptor 0 read error: %d\n",
                    err);
        dev->string_langid = -1;
        return -EPIPE;
    }

    /* always use the first langid listed */
    dev->string_langid = tbuf[2] | (tbuf[3] << 8);
    dev->have_langid = 1;
    dev_dbg(&dev->dev, "default language 0x%04x\n",
                dev->string_langid);
    return 0;
}

int usb_string(struct usb_device *dev, int index, char *buf, size_t size)
{
    unsigned char *tbuf;
    int err;

    if (dev->state == USB_STATE_SUSPENDED)
        return -EHOSTUNREACH;
    if (size <= 0 || !buf || !index)
        return -EINVAL;
    buf[0] = 0;
    tbuf = kmalloc(256, GFP_NOIO);
    if (!tbuf)
        return -ENOMEM;

    err = usb_get_langid(dev, tbuf);
    if (err < 0)
        goto errout;

    err = usb_string_sub(dev, dev->string_langid, index, tbuf);
    if (err < 0)
        goto errout;

    size--;     /* leave room for trailing NULL char in output buffer */
    err = utf16s_to_utf8s((wchar_t *) &tbuf[2], (err - 2) / 2,
            UTF16_LITTLE_ENDIAN, buf, size);
    buf[err] = 0;

    if (tbuf[1] != USB_DT_STRING)
        dev_dbg(&dev->dev,
            "wrong descriptor type %02x for string %d (\"%s\")\n",
            tbuf[1], index, buf);

 errout:
    kfree(tbuf);
    return err;
}
EXPORT_SYMBOL_GPL(usb_string);

/* one UTF-8-encoded 16-bit character has at most three bytes */
#define MAX_USB_STRING_SIZE (127 * 3 + 1)

char *usb_cache_string(struct usb_device *udev, int index)
{
    char *buf;
    char *smallbuf = NULL;
    int len;

    if (index <= 0)
        return NULL;

    buf = kmalloc(MAX_USB_STRING_SIZE, GFP_NOIO);
    if (buf) {
        len = usb_string(udev, index, buf, MAX_USB_STRING_SIZE);
        if (len > 0) {
            smallbuf = kmalloc(++len, GFP_NOIO);
            if (!smallbuf)
                return buf;
            memcpy(smallbuf, buf, len);
        }
        kfree(buf);
    }
    return smallbuf;
}

/*
 * usb_get_device_descriptor - (re)reads the device descriptor (usbcore)
 * @dev: the device whose device descriptor is being updated
 * @size: how much of the descriptor to read
 * Context: !in_interrupt ()
 *
 * Updates the copy of the device descriptor stored in the device structure,
 * which dedicates space for this purpose.
 *
 * Not exported, only for use by the core.  If drivers really want to read
 * the device descriptor directly, they can call usb_get_descriptor() with
 * type = USB_DT_DEVICE and index = 0.
 *
 * This call is synchronous, and may not be used in an interrupt context.
 *
 * Returns the number of bytes received on success, or else the status code
 * returned by the underlying usb_control_msg() call.
 */
int usb_get_device_descriptor(struct usb_device *dev, unsigned int size)
{
    struct usb_device_descriptor *desc;
    int ret;

    if (size > sizeof(*desc))
        return -EINVAL;
    desc = kmalloc(sizeof(*desc), GFP_NOIO);
    if (!desc)
        return -ENOMEM;

    ret = usb_get_descriptor(dev, USB_DT_DEVICE, 0, desc, size);
    if (ret >= 0)
        memcpy(&dev->descriptor, desc, size);
    kfree(desc);
    return ret;
}

int usb_get_status(struct usb_device *dev, int type, int target, void *data)
{
    int ret;
    u16 *status = kmalloc(sizeof(*status), GFP_KERNEL);

    if (!status)
        return -ENOMEM;

    ret = usb_control_msg(dev, usb_rcvctrlpipe(dev, 0),
        USB_REQ_GET_STATUS, USB_DIR_IN | type, 0, target, status,
        sizeof(*status), USB_CTRL_GET_TIMEOUT);

    *(u16 *)data = *status;
    kfree(status);
    return ret;
}
EXPORT_SYMBOL_GPL(usb_get_status);

int usb_clear_halt(struct usb_device *dev, int pipe)
{
    int result;
    int endp = usb_pipeendpoint(pipe);

    if (usb_pipein(pipe))
        endp |= USB_DIR_IN;

    /* we don't care if it wasn't halted first. in fact some devices
     * (like some ibmcam model 1 units) seem to expect hosts to make
     * this request for iso endpoints, which can't halt!
     */
    result = usb_control_msg(dev, usb_sndctrlpipe(dev, 0),
        USB_REQ_CLEAR_FEATURE, USB_RECIP_ENDPOINT,
        USB_ENDPOINT_HALT, endp, NULL, 0,
        USB_CTRL_SET_TIMEOUT);

    /* don't un-halt or force to DATA0 except on success */
    if (result < 0)
        return result;

    /* NOTE:  seems like Microsoft and Apple don't bother verifying
     * the clear "took", so some devices could lock up if you check...
     * such as the Hagiwara FlashGate DUAL.  So we won't bother.
     *
     * NOTE:  make sure the logic here doesn't diverge much from
     * the copy in usb-storage, for as long as we need two copies.
     */

    usb_reset_endpoint(dev, endp);

    return 0;
}
EXPORT_SYMBOL_GPL(usb_clear_halt);

static int create_intf_ep_devs(struct usb_interface *intf)
{
    struct usb_device *udev = interface_to_usbdev(intf);
    struct usb_host_interface *alt = intf->cur_altsetting;
    int i;

    if (intf->ep_devs_created || intf->unregistering)
        return 0;

    for (i = 0; i < alt->desc.bNumEndpoints; ++i)
        (void) usb_create_ep_devs(&intf->dev, &alt->endpoint[i], udev);
    intf->ep_devs_created = 1;
    return 0;
}

static void remove_intf_ep_devs(struct usb_interface *intf)
{
    struct usb_host_interface *alt = intf->cur_altsetting;
    int i;

    if (!intf->ep_devs_created)
        return;

    for (i = 0; i < alt->desc.bNumEndpoints; ++i)
        usb_remove_ep_devs(&alt->endpoint[i]);
    intf->ep_devs_created = 0;
}

void usb_disable_endpoint(struct usb_device *dev, unsigned int epaddr,
        bool reset_hardware)
{
    unsigned int epnum = epaddr & USB_ENDPOINT_NUMBER_MASK;
    struct usb_host_endpoint *ep;

    if (!dev)
        return;

    if (usb_endpoint_out(epaddr)) {
        ep = dev->ep_out[epnum];
        if (reset_hardware)
            dev->ep_out[epnum] = NULL;
    } else {
        ep = dev->ep_in[epnum];
        if (reset_hardware)
            dev->ep_in[epnum] = NULL;
    }
    if (ep) {
        ep->enabled = 0;
        usb_hcd_flush_endpoint(dev, ep);
        if (reset_hardware)
            usb_hcd_disable_endpoint(dev, ep);
    }
}

void usb_reset_endpoint(struct usb_device *dev, unsigned int epaddr)
{
    unsigned int epnum = epaddr & USB_ENDPOINT_NUMBER_MASK;
    struct usb_host_endpoint *ep;

    if (usb_endpoint_out(epaddr))
        ep = dev->ep_out[epnum];
    else
        ep = dev->ep_in[epnum];
    if (ep)
        usb_hcd_reset_endpoint(dev, ep);
}
EXPORT_SYMBOL_GPL(usb_reset_endpoint);


void usb_disable_interface(struct usb_device *dev, struct usb_interface *intf,
        bool reset_hardware)
{
    struct usb_host_interface *alt = intf->cur_altsetting;
    int i;

    for (i = 0; i < alt->desc.bNumEndpoints; ++i) {
        usb_disable_endpoint(dev,
                alt->endpoint[i].desc.bEndpointAddress,
                reset_hardware);
    }
}

void usb_disable_device(struct usb_device *dev, int skip_ep0)
{
    int i;
    struct usb_hcd *hcd = bus_to_hcd(dev->bus);

    /* getting rid of interfaces will disconnect
     * any drivers bound to them (a key side effect)
     */
    if (dev->actconfig) {
        /*
         * FIXME: In order to avoid self-deadlock involving the
         * bandwidth_mutex, we have to mark all the interfaces
         * before unregistering any of them.
         */
        for (i = 0; i < dev->actconfig->desc.bNumInterfaces; i++)
            dev->actconfig->interface[i]->unregistering = 1;

        for (i = 0; i < dev->actconfig->desc.bNumInterfaces; i++) {
            struct usb_interface    *interface;

            /* remove this interface if it has been registered */
            interface = dev->actconfig->interface[i];
            if (!device_is_registered(&interface->dev))
                continue;
            dev_dbg(&dev->dev, "unregistering interface %s\n",
                dev_name(&interface->dev));
            remove_intf_ep_devs(interface);
            device_del(&interface->dev);
        }

        /* Now that the interfaces are unbound, nobody should
         * try to access them.
         */
        for (i = 0; i < dev->actconfig->desc.bNumInterfaces; i++) {
            put_device(&dev->actconfig->interface[i]->dev);
            dev->actconfig->interface[i] = NULL;
        }
        usb_unlocked_disable_lpm(dev);
        usb_disable_ltm(dev);
        dev->actconfig = NULL;
        if (dev->state == USB_STATE_CONFIGURED)
            usb_set_device_state(dev, USB_STATE_ADDRESS);
    }

    dev_dbg(&dev->dev, "%s nuking %s URBs\n", __func__,
        skip_ep0 ? "non-ep0" : "all");
    if (hcd->driver->check_bandwidth) {
        /* First pass: Cancel URBs, leave endpoint pointers intact. */
        for (i = skip_ep0; i < 16; ++i) {
            usb_disable_endpoint(dev, i, false);
            usb_disable_endpoint(dev, i + USB_DIR_IN, false);
        }
        /* Remove endpoints from the host controller internal state */
        mutex_lock(hcd->bandwidth_mutex);
        usb_hcd_alloc_bandwidth(dev, NULL, NULL, NULL);
        mutex_unlock(hcd->bandwidth_mutex);
        /* Second pass: remove endpoint pointers */
    }
    for (i = skip_ep0; i < 16; ++i) {
        usb_disable_endpoint(dev, i, true);
        usb_disable_endpoint(dev, i + USB_DIR_IN, true);
    }
}

void usb_enable_endpoint(struct usb_device *dev, struct usb_host_endpoint *ep,
        bool reset_ep)
{
    int epnum = usb_endpoint_num(&ep->desc);
    int is_out = usb_endpoint_dir_out(&ep->desc);
    int is_control = usb_endpoint_xfer_control(&ep->desc);

    if (reset_ep)
        usb_hcd_reset_endpoint(dev, ep);
    if (is_out || is_control)
        dev->ep_out[epnum] = ep;
    if (!is_out || is_control)
        dev->ep_in[epnum] = ep;
    ep->enabled = 1;
}

void usb_enable_interface(struct usb_device *dev,
        struct usb_interface *intf, bool reset_eps)
{
    struct usb_host_interface *alt = intf->cur_altsetting;
    int i;

    for (i = 0; i < alt->desc.bNumEndpoints; ++i)
        usb_enable_endpoint(dev, &alt->endpoint[i], reset_eps);
}

int usb_set_interface(struct usb_device *dev, int interface, int alternate)
{
    struct usb_interface *iface;
    struct usb_host_interface *alt;
    struct usb_hcd *hcd = bus_to_hcd(dev->bus);
    int ret;
    int manual = 0;
    unsigned int epaddr;
    unsigned int pipe;

    if (dev->state == USB_STATE_SUSPENDED)
        return -EHOSTUNREACH;

    iface = usb_ifnum_to_if(dev, interface);
    if (!iface) {
        dev_dbg(&dev->dev, "selecting invalid interface %d\n",
            interface);
        return -EINVAL;
    }
    if (iface->unregistering)
        return -ENODEV;

    alt = usb_altnum_to_altsetting(iface, alternate);
    if (!alt) {
        dev_warn(&dev->dev, "selecting invalid altsetting %d\n",
             alternate);
        return -EINVAL;
    }

    /* Make sure we have enough bandwidth for this alternate interface.
     * Remove the current alt setting and add the new alt setting.
     */
    mutex_lock(hcd->bandwidth_mutex);
    /* Disable LPM, and re-enable it once the new alt setting is installed,
     * so that the xHCI driver can recalculate the U1/U2 timeouts.
     */
    if (usb_disable_lpm(dev)) {
        dev_err(&iface->dev, "%s Failed to disable LPM\n.", __func__);
        mutex_unlock(hcd->bandwidth_mutex);
        return -ENOMEM;
    }
    ret = usb_hcd_alloc_bandwidth(dev, NULL, iface->cur_altsetting, alt);
    if (ret < 0) {
        dev_info(&dev->dev, "Not enough bandwidth for altsetting %d\n",
                alternate);
        usb_enable_lpm(dev);
        mutex_unlock(hcd->bandwidth_mutex);
        return ret;
    }

    if (dev->quirks & USB_QUIRK_NO_SET_INTF)
        ret = -EPIPE;
    else
        ret = usb_control_msg(dev, usb_sndctrlpipe(dev, 0),
                   USB_REQ_SET_INTERFACE, USB_RECIP_INTERFACE,
                   alternate, interface, NULL, 0, 5000);

    /* 9.4.10 says devices don't need this and are free to STALL the
     * request if the interface only has one alternate setting.
     */
    if (ret == -EPIPE && iface->num_altsetting == 1) {
        dev_dbg(&dev->dev,
            "manual set_interface for iface %d, alt %d\n",
            interface, alternate);
        manual = 1;
    } else if (ret < 0) {
        /* Re-instate the old alt setting */
        usb_hcd_alloc_bandwidth(dev, NULL, alt, iface->cur_altsetting);
        usb_enable_lpm(dev);
        mutex_unlock(hcd->bandwidth_mutex);
        return ret;
    }
    mutex_unlock(hcd->bandwidth_mutex);

    /* FIXME drivers shouldn't need to replicate/bugfix the logic here
     * when they implement async or easily-killable versions of this or
     * other "should-be-internal" functions (like clear_halt).
     * should hcd+usbcore postprocess control requests?
     */

    /* prevent submissions using previous endpoint settings */
    if (iface->cur_altsetting != alt) {
        remove_intf_ep_devs(iface);
        usb_remove_sysfs_intf_files(iface);
    }
    usb_disable_interface(dev, iface, true);

    iface->cur_altsetting = alt;

    /* Now that the interface is installed, re-enable LPM. */
    usb_unlocked_enable_lpm(dev);

    /* If the interface only has one altsetting and the device didn't
     * accept the request, we attempt to carry out the equivalent action
     * by manually clearing the HALT feature for each endpoint in the
     * new altsetting.
     */
    if (manual) {
        int i;

        for (i = 0; i < alt->desc.bNumEndpoints; i++) {
            epaddr = alt->endpoint[i].desc.bEndpointAddress;
            pipe = __create_pipe(dev,
                    USB_ENDPOINT_NUMBER_MASK & epaddr) |
                    (usb_endpoint_out(epaddr) ?
                    USB_DIR_OUT : USB_DIR_IN);

            usb_clear_halt(dev, pipe);
        }
    }

    /* 9.1.1.5: reset toggles for all endpoints in the new altsetting
     *
     * Note:
     * Despite EP0 is always present in all interfaces/AS, the list of
     * endpoints from the descriptor does not contain EP0. Due to its
     * omnipresence one might expect EP0 being considered "affected" by
     * any SetInterface request and hence assume toggles need to be reset.
     * However, EP0 toggles are re-synced for every individual transfer
     * during the SETUP stage - hence EP0 toggles are "don't care" here.
     * (Likewise, EP0 never "halts" on well designed devices.)
     */
    usb_enable_interface(dev, iface, true);
    if (device_is_registered(&iface->dev)) {
        usb_create_sysfs_intf_files(iface);
        create_intf_ep_devs(iface);
    }
    return 0;
}
EXPORT_SYMBOL_GPL(usb_set_interface);

int usb_reset_configuration(struct usb_device *dev)
{
    int         i, retval;
    struct usb_host_config  *config;
    struct usb_hcd *hcd = bus_to_hcd(dev->bus);

    if (dev->state == USB_STATE_SUSPENDED)
        return -EHOSTUNREACH;

    /* caller must have locked the device and must own
     * the usb bus readlock (so driver bindings are stable);
     * calls during probe() are fine
     */

    for (i = 1; i < 16; ++i) {
        usb_disable_endpoint(dev, i, true);
        usb_disable_endpoint(dev, i + USB_DIR_IN, true);
    }

    config = dev->actconfig;
    retval = 0;
    mutex_lock(hcd->bandwidth_mutex);
    /* Disable LPM, and re-enable it once the configuration is reset, so
     * that the xHCI driver can recalculate the U1/U2 timeouts.
     */
    if (usb_disable_lpm(dev)) {
        dev_err(&dev->dev, "%s Failed to disable LPM\n.", __func__);
        mutex_unlock(hcd->bandwidth_mutex);
        return -ENOMEM;
    }
    /* Make sure we have enough bandwidth for each alternate setting 0 */
    for (i = 0; i < config->desc.bNumInterfaces; i++) {
        struct usb_interface *intf = config->interface[i];
        struct usb_host_interface *alt;

        alt = usb_altnum_to_altsetting(intf, 0);
        if (!alt)
            alt = &intf->altsetting[0];
        if (alt != intf->cur_altsetting)
            retval = usb_hcd_alloc_bandwidth(dev, NULL,
                    intf->cur_altsetting, alt);
        if (retval < 0)
            break;
    }
    /* If not, reinstate the old alternate settings */
    if (retval < 0) {
reset_old_alts:
        for (i--; i >= 0; i--) {
            struct usb_interface *intf = config->interface[i];
            struct usb_host_interface *alt;

            alt = usb_altnum_to_altsetting(intf, 0);
            if (!alt)
                alt = &intf->altsetting[0];
            if (alt != intf->cur_altsetting)
                usb_hcd_alloc_bandwidth(dev, NULL,
                        alt, intf->cur_altsetting);
        }
        usb_enable_lpm(dev);
        mutex_unlock(hcd->bandwidth_mutex);
        return retval;
    }
    retval = usb_control_msg(dev, usb_sndctrlpipe(dev, 0),
            USB_REQ_SET_CONFIGURATION, 0,
            config->desc.bConfigurationValue, 0,
            NULL, 0, USB_CTRL_SET_TIMEOUT);
    if (retval < 0)
        goto reset_old_alts;
    mutex_unlock(hcd->bandwidth_mutex);

    /* re-init hc/hcd interface/endpoint state */
    for (i = 0; i < config->desc.bNumInterfaces; i++) {
        struct usb_interface *intf = config->interface[i];
        struct usb_host_interface *alt;

        alt = usb_altnum_to_altsetting(intf, 0);

        /* No altsetting 0?  We'll assume the first altsetting.
         * We could use a GetInterface call, but if a device is
         * so non-compliant that it doesn't have altsetting 0
         * then I wouldn't trust its reply anyway.
         */
        if (!alt)
            alt = &intf->altsetting[0];

        if (alt != intf->cur_altsetting) {
            remove_intf_ep_devs(intf);
            usb_remove_sysfs_intf_files(intf);
        }
        intf->cur_altsetting = alt;
        usb_enable_interface(dev, intf, true);
        if (device_is_registered(&intf->dev)) {
            usb_create_sysfs_intf_files(intf);
            create_intf_ep_devs(intf);
        }
    }
    /* Now that the interfaces are installed, re-enable LPM. */
    usb_unlocked_enable_lpm(dev);
    return 0;
}
EXPORT_SYMBOL_GPL(usb_reset_configuration);

static void usb_release_interface(struct device *dev)
{
    struct usb_interface *intf = to_usb_interface(dev);
    struct usb_interface_cache *intfc =
            altsetting_to_usb_interface_cache(intf->altsetting);

    kref_put(&intfc->ref, usb_release_interface_cache);
    kfree(intf);
}

#ifdef  CONFIG_HOTPLUG
static int usb_if_uevent(struct device *dev, struct kobj_uevent_env *env)
{
    struct usb_device *usb_dev;
    struct usb_interface *intf;
    struct usb_host_interface *alt;

    intf = to_usb_interface(dev);
    usb_dev = interface_to_usbdev(intf);
    alt = intf->cur_altsetting;

    if (add_uevent_var(env, "INTERFACE=%d/%d/%d",
           alt->desc.bInterfaceClass,
           alt->desc.bInterfaceSubClass,
           alt->desc.bInterfaceProtocol))
        return -ENOMEM;

    if (add_uevent_var(env,
           "MODALIAS=usb:"
           "v%04Xp%04Xd%04Xdc%02Xdsc%02Xdp%02Xic%02Xisc%02Xip%02Xin%02X",
           le16_to_cpu(usb_dev->descriptor.idVendor),
           le16_to_cpu(usb_dev->descriptor.idProduct),
           le16_to_cpu(usb_dev->descriptor.bcdDevice),
           usb_dev->descriptor.bDeviceClass,
           usb_dev->descriptor.bDeviceSubClass,
           usb_dev->descriptor.bDeviceProtocol,
           alt->desc.bInterfaceClass,
           alt->desc.bInterfaceSubClass,
           alt->desc.bInterfaceProtocol,
           alt->desc.bInterfaceNumber))
        return -ENOMEM;

    return 0;
}

#else

static int usb_if_uevent(struct device *dev, struct kobj_uevent_env *env)
{
    return -ENODEV;
}
#endif  /* CONFIG_HOTPLUG */

struct device_type usb_if_device_type = {
    .name =     "usb_interface",
    .release =  usb_release_interface,
    .uevent =   usb_if_uevent,
};

static struct usb_interface_assoc_descriptor *find_iad(struct usb_device *dev,
                        struct usb_host_config *config,
                        u8 inum)
{
    struct usb_interface_assoc_descriptor *retval = NULL;
    struct usb_interface_assoc_descriptor *intf_assoc;
    int first_intf;
    int last_intf;
    int i;

    for (i = 0; (i < USB_MAXIADS && config->intf_assoc[i]); i++) {
        intf_assoc = config->intf_assoc[i];
        if (intf_assoc->bInterfaceCount == 0)
            continue;

        first_intf = intf_assoc->bFirstInterface;
        last_intf = first_intf + (intf_assoc->bInterfaceCount - 1);
        if (inum >= first_intf && inum <= last_intf) {
            if (!retval)
                retval = intf_assoc;
            else
                dev_err(&dev->dev, "Interface #%d referenced"
                    " by multiple IADs\n", inum);
        }
    }

    return retval;
}


/*
 * Internal function to queue a device reset
 *
 * This is initialized into the workstruct in 'struct
 * usb_device->reset_ws' that is launched by
 * message.c:usb_set_configuration() when initializing each 'struct
 * usb_interface'.
 *
 * It is safe to get the USB device without reference counts because
 * the life cycle of @iface is bound to the life cycle of @udev. Then,
 * this function will be ran only if @iface is alive (and before
 * freeing it any scheduled instances of it will have been cancelled).
 *
 * We need to set a flag (usb_dev->reset_running) because when we call
 * the reset, the interfaces might be unbound. The current interface
 * cannot try to remove the queued work as it would cause a deadlock
 * (you cannot remove your work from within your executing
 * workqueue). This flag lets it know, so that
 * usb_cancel_queued_reset() doesn't try to do it.
 *
 * See usb_queue_reset_device() for more details
 */
static void __usb_queue_reset_device(struct work_struct *ws)
{
    int rc;
    struct usb_interface *iface =
        container_of(ws, struct usb_interface, reset_ws);
    struct usb_device *udev = interface_to_usbdev(iface);

    rc = usb_lock_device_for_reset(udev, iface);
    if (rc >= 0) {
        iface->reset_running = 1;
        usb_reset_device(udev);
        iface->reset_running = 0;
        usb_unlock_device(udev);
    }
}


/*
 * usb_set_configuration - Makes a particular device setting be current
 * @dev: the device whose configuration is being updated
 * @configuration: the configuration being chosen.
 * Context: !in_interrupt(), caller owns the device lock
 *
 * This is used to enable non-default device modes.  Not all devices
 * use this kind of configurability; many devices only have one
 * configuration.
 *
 * @configuration is the value of the configuration to be installed.
 * According to the USB spec (e.g. section 9.1.1.5), configuration values
 * must be non-zero; a value of zero indicates that the device in
 * unconfigured.  However some devices erroneously use 0 as one of their
 * configuration values.  To help manage such devices, this routine will
 * accept @configuration = -1 as indicating the device should be put in
 * an unconfigured state.
 *
 * USB device configurations may affect Linux interoperability,
 * power consumption and the functionality available.  For example,
 * the default configuration is limited to using 100mA of bus power,
 * so that when certain device functionality requires more power,
 * and the device is bus powered, that functionality should be in some
 * non-default device configuration.  Other device modes may also be
 * reflected as configuration options, such as whether two ISDN
 * channels are available independently; and choosing between open
 * standard device protocols (like CDC) or proprietary ones.
 *
 * Note that a non-authorized device (dev->authorized == 0) will only
 * be put in unconfigured mode.
 *
 * Note that USB has an additional level of device configurability,
 * associated with interfaces.  That configurability is accessed using
 * usb_set_interface().
 *
 * This call is synchronous. The calling context must be able to sleep,
 * must own the device lock, and must not hold the driver model's USB
 * bus mutex; usb interface driver probe() methods cannot use this routine.
 *
 * Returns zero on success, or else the status code returned by the
 * underlying call that failed.  On successful completion, each interface
 * in the original device configuration has been destroyed, and each one
 * in the new configuration has been probed by all relevant usb device
 * drivers currently known to the kernel.
 */
int usb_set_configuration(struct usb_device *dev, int configuration)
{
    int i, ret;
    struct usb_host_config *cp = NULL;
    struct usb_interface **new_interfaces = NULL;
    struct usb_hcd *hcd = bus_to_hcd(dev->bus);
    int n, nintf;

    if (dev->authorized == 0 || configuration == -1)
        configuration = 0;
    else {
        for (i = 0; i < dev->descriptor.bNumConfigurations; i++) {
            if (dev->config[i].desc.bConfigurationValue ==
                    configuration) {
                cp = &dev->config[i];
                break;
            }
        }
    }
    if ((!cp && configuration != 0))
        return -EINVAL;

    /* The USB spec says configuration 0 means unconfigured.
     * But if a device includes a configuration numbered 0,
     * we will accept it as a correctly configured state.
     * Use -1 if you really want to unconfigure the device.
     */
    if (cp && configuration == 0)
        dev_warn(&dev->dev, "config 0 descriptor??\n");

    /* Allocate memory for new interfaces before doing anything else,
     * so that if we run out then nothing will have changed. */
    n = nintf = 0;
    if (cp) {
        nintf = cp->desc.bNumInterfaces;
        new_interfaces = kmalloc(nintf * sizeof(*new_interfaces),
                GFP_NOIO);
        if (!new_interfaces) {
            dev_err(&dev->dev, "Out of memory\n");
            return -ENOMEM;
        }

        for (; n < nintf; ++n) {
            new_interfaces[n] = kzalloc(
                    sizeof(struct usb_interface),
                    GFP_NOIO);
            if (!new_interfaces[n]) {
                dev_err(&dev->dev, "Out of memory\n");
                ret = -ENOMEM;
free_interfaces:
                while (--n >= 0)
                    kfree(new_interfaces[n]);
                kfree(new_interfaces);
                return ret;
            }
        }

        i = dev->bus_mA - cp->desc.bMaxPower * 2;
        if (i < 0)
            dev_warn(&dev->dev, "new config #%d exceeds power "
                    "limit by %dmA\n",
                    configuration, -i);
    }

    /* Wake up the device so we can send it the Set-Config request */
    ret = usb_autoresume_device(dev);
    if (ret)
        goto free_interfaces;

    /* if it's already configured, clear out old state first.
     * getting rid of old interfaces means unbinding their drivers.
     */
    if (dev->state != USB_STATE_ADDRESS)
        usb_disable_device(dev, 1); /* Skip ep0 */

    /* Get rid of pending async Set-Config requests for this device */
    cancel_async_set_config(dev);

    /* Make sure we have bandwidth (and available HCD resources) for this
     * configuration.  Remove endpoints from the schedule if we're dropping
     * this configuration to set configuration 0.  After this point, the
     * host controller will not allow submissions to dropped endpoints.  If
     * this call fails, the device state is unchanged.
     */
    mutex_lock(hcd->bandwidth_mutex);
    /* Disable LPM, and re-enable it once the new configuration is
     * installed, so that the xHCI driver can recalculate the U1/U2
     * timeouts.
     */
    if (dev->actconfig && usb_disable_lpm(dev)) {
        dev_err(&dev->dev, "%s Failed to disable LPM\n.", __func__);
        mutex_unlock(hcd->bandwidth_mutex);
        return -ENOMEM;
    }
    ret = usb_hcd_alloc_bandwidth(dev, cp, NULL, NULL);
    if (ret < 0) {
        if (dev->actconfig)
            usb_enable_lpm(dev);
        mutex_unlock(hcd->bandwidth_mutex);
        usb_autosuspend_device(dev);
        goto free_interfaces;
    }

    ret = usb_control_msg(dev, usb_sndctrlpipe(dev, 0),
                  USB_REQ_SET_CONFIGURATION, 0, configuration, 0,
                  NULL, 0, USB_CTRL_SET_TIMEOUT);
    if (ret < 0) {
        /* All the old state is gone, so what else can we do?
         * The device is probably useless now anyway.
         */
        cp = NULL;
    }

    dev->actconfig = cp;
    if (!cp) {
        usb_set_device_state(dev, USB_STATE_ADDRESS);
        usb_hcd_alloc_bandwidth(dev, NULL, NULL, NULL);
        /* Leave LPM disabled while the device is unconfigured. */
        mutex_unlock(hcd->bandwidth_mutex);
        usb_autosuspend_device(dev);
        goto free_interfaces;
    }
    mutex_unlock(hcd->bandwidth_mutex);
    usb_set_device_state(dev, USB_STATE_CONFIGURED);

    /* Initialize the new interface structures and the
     * hc/hcd/usbcore interface/endpoint state.
     */
    for (i = 0; i < nintf; ++i) {
        struct usb_interface_cache *intfc;
        struct usb_interface *intf;
        struct usb_host_interface *alt;

        cp->interface[i] = intf = new_interfaces[i];
        intfc = cp->intf_cache[i];
        intf->altsetting = intfc->altsetting;
        intf->num_altsetting = intfc->num_altsetting;
        kref_get(&intfc->ref);

        alt = usb_altnum_to_altsetting(intf, 0);

        /* No altsetting 0?  We'll assume the first altsetting.
         * We could use a GetInterface call, but if a device is
         * so non-compliant that it doesn't have altsetting 0
         * then I wouldn't trust its reply anyway.
         */
        if (!alt)
            alt = &intf->altsetting[0];

        intf->intf_assoc =
            find_iad(dev, cp, alt->desc.bInterfaceNumber);
        intf->cur_altsetting = alt;
        usb_enable_interface(dev, intf, true);
        intf->dev.parent = &dev->dev;
        intf->dev.driver = NULL;
        intf->dev.bus = &usb_bus_type;
        intf->dev.type = &usb_if_device_type;
        intf->dev.groups = usb_interface_groups;
        intf->dev.dma_mask = dev->dev.dma_mask;
        INIT_WORK(&intf->reset_ws, __usb_queue_reset_device);
        intf->minor = -1;
        device_initialize(&intf->dev);
        pm_runtime_no_callbacks(&intf->dev);
        dev_set_name(&intf->dev, "%d-%s:%d.%d",
            dev->bus->busnum, dev->devpath,
            configuration, alt->desc.bInterfaceNumber);
    }
    kfree(new_interfaces);

    if (cp->string == NULL &&
            !(dev->quirks & USB_QUIRK_CONFIG_INTF_STRINGS))
        cp->string = usb_cache_string(dev, cp->desc.iConfiguration);

    /* Now that the interfaces are installed, re-enable LPM. */
    usb_unlocked_enable_lpm(dev);
    /* Enable LTM if it was turned off by usb_disable_device. */
    usb_enable_ltm(dev);

    /* Now that all the interfaces are set up, register them
     * to trigger binding of drivers to interfaces.  probe()
     * routines may install different altsettings and may
     * claim() any interfaces not yet bound.  Many class drivers
     * need that: CDC, audio, video, etc.
     */
    for (i = 0; i < nintf; ++i) {
        struct usb_interface *intf = cp->interface[i];

        dev_dbg(&dev->dev,
            "adding %s (config #%d, interface %d)\n",
            dev_name(&intf->dev), configuration,
            intf->cur_altsetting->desc.bInterfaceNumber);
        device_enable_async_suspend(&intf->dev);
        ret = device_add(&intf->dev);
        if (ret != 0) {
            dev_err(&dev->dev, "device_add(%s) --> %d\n",
                dev_name(&intf->dev), ret);
            continue;
        }
        create_intf_ep_devs(intf);
    }

    usb_autosuspend_device(dev);
    return 0;
}

static LIST_HEAD(set_config_list);
static DEFINE_SPINLOCK(set_config_lock);

struct set_config_request {
    struct usb_device   *udev;
    int         config;
    struct work_struct  work;
    struct list_head    node;
};

/* Worker routine for usb_driver_set_configuration() */
static void driver_set_config_work(struct work_struct *work)
{
    struct set_config_request *req =
        container_of(work, struct set_config_request, work);
    struct usb_device *udev = req->udev;

    usb_lock_device(udev);
    spin_lock(&set_config_lock);
    list_del(&req->node);
    spin_unlock(&set_config_lock);

    if (req->config >= -1)      /* Is req still valid? */
        usb_set_configuration(udev, req->config);
    usb_unlock_device(udev);
    usb_put_dev(udev);
    kfree(req);
}

/* Cancel pending Set-Config requests for a device whose configuration
 * was just changed
 */
static void cancel_async_set_config(struct usb_device *udev)
{
    struct set_config_request *req;

    spin_lock(&set_config_lock);
    list_for_each_entry(req, &set_config_list, node) {
        if (req->udev == udev)
            req->config = -999; /* Mark as cancelled */
    }
    spin_unlock(&set_config_lock);
}

int usb_driver_set_configuration(struct usb_device *udev, int config)
{
    struct set_config_request *req;

    req = kmalloc(sizeof(*req), GFP_KERNEL);
    if (!req)
        return -ENOMEM;
    req->udev = udev;
    req->config = config;
    INIT_WORK(&req->work, driver_set_config_work);

    spin_lock(&set_config_lock);
    list_add(&req->node, &set_config_list);
    spin_unlock(&set_config_lock);

    usb_get_dev(udev);
    schedule_work(&req->work);
    return 0;
}
EXPORT_SYMBOL_GPL(usb_driver_set_configuration);