ret = usb_device_dump(&buf, &nbytes, &skip_bytes, ppos, bus->root_hub, bus, 0, 0, 0);
usb_unlock_device(bus->root_hub);
if (ret < 0) {
ret = usb_device_dump(&buf, &nbytes, &skip_bytes, ppos, bus->root_hub, bus, 0, 0, 0);
usb_unlock_device(bus->root_hub);
if (ret < 0) {