netmap_mem_deref
netmap_mem_deref(na_dr->nm_mem, na_dr);
netmap_mem_deref(na_dr->nm_mem, na_dr);
netmap_mem_deref(na->nm_mem, na);
netmap_mem_deref(nmd, na);
int netmap_mem_deref(struct netmap_mem_d *, struct netmap_adapter *);