kern_recvit
error = kern_recvit(td, uap->s, &msg, UIO_USERSPACE, controlp);
error = kern_recvit(td, args->s, &msg, UIO_SYSSPACE, NULL);
error = kern_recvit(td, s, msg, UIO_SYSSPACE, controlp);
error = kern_recvit(td, s, mp, UIO_USERSPACE, NULL);
int kern_recvit(struct thread *td, int s, struct msghdr *mp,