rw_read_held
RW_ASSERT(rw, rw_read_held(rw));
if (rw_read_held(&vip->vi_lock))
KASSERT(rw_read_held(&p->p_reflock));
KASSERT(rw_read_held((ifp)->if_afdata_lock))
return rw_read_held(&in6_multilock);
KASSERT(rw_read_held(rw));
return rw_read_held(rw) || rw_write_held(rw);
int rw_read_held(krwlock_t *);
rw_read_held(&swap_syscall_lock));