dev_to_instance
if ((inst = dev_to_instance(dev)) < 0)
dip = hold_devi(major, dev_to_instance(dev), flags);
if ((instance = dev_to_instance(dev)) == -1)
if ((instance = dev_to_instance(devt)) == -1)
extern int dev_to_instance(dev_t);
dev_to_instance(vnp->v_rdev), 0)) == NULL) {