VOP_KQFILTER
error = VOP_KQFILTER(UPPERVP(ap->a_vp), ap->a_kn);
error = VOP_KQFILTER(LOWERVP(ap->a_vp), ap->a_kn);
return VOP_KQFILTER(tvp, ap->a_kn);
return (VOP_KQFILTER(ttyvp, kn));
return VOP_KQFILTER(fp->f_vnode, kn);
error = VOP_KQFILTER(vp, kn);
int VOP_KQFILTER(struct vnode *, struct knote *);