cdev_open
if ((error = cdev_open(tp->t_dev, O_NONBLOCK|flags,
if ((error = cdev_open(tp->t_dev, O_NONBLOCK|flags,
return cdev_open(devctty, ap->a_mode, 0, curlwp);
error = cdev_open(dev, ap->a_mode, S_IFCHR, l);
dev_type_open(cdev_open);