checkfdclosed
if (checkfdclosed(td, p->p_fd, fd, fp, closedcounter)) {
checkfdclosed(curthread, fdp, kev->ident, kn->kn_fp,
checkfdclosed(td, kq->kq_fdp, kn->kn_kevent.ident,
int checkfdclosed(thread_t, struct filedesc *, int, struct file *, int);