static int acm_start_wb(struct acm *acm, struct acm_wb *wb)
{
	int rc;

	acm->transmitting++;

	wb->urb->transfer_buffer = wb->buf;
	wb->urb->transfer_dma = wb->dmah;
	wb->urb->transfer_buffer_length = wb->len;
	wb->urb->dev = acm->dev;

	rc = usb_submit_urb(wb->urb, GFP_ATOMIC);
	if (rc < 0) {
		dev_err(&acm->data->dev,
			"%s - usb_submit_urb(write bulk) failed: %d\n",
			__func__, rc);
		acm_write_done(acm, wb);
	}
	return rc;
}

Unknown