static int set_serial_info(struct acm *acm,
				struct serial_struct __user *newinfo)
{
	struct serial_struct new_serial;
	unsigned int closing_wait, close_delay;
	int retval = 0;

	if (copy_from_user(&new_serial, newinfo, sizeof(new_serial)))
		return -EFAULT;

	close_delay = new_serial.close_delay * 10;
	closing_wait = new_serial.closing_wait == ASYNC_CLOSING_WAIT_NONE ?
			ASYNC_CLOSING_WAIT_NONE : new_serial.closing_wait * 10;

	mutex_lock(&acm->port.mutex);

	if (!capable(CAP_SYS_ADMIN)) {
		if ((close_delay != acm->port.close_delay) ||
		    (closing_wait != acm->port.closing_wait))
			retval = -EPERM;
		else
			retval = -EOPNOTSUPP;
	} else {
		acm->port.close_delay  = close_delay;
		acm->port.closing_wait = closing_wait;
	}

	mutex_unlock(&acm->port.mutex);
	return retval;
}

Unknown