PF_C_COUNTER
{ .type = PF_C_COUNTER, .off = _OUT(counter), .cb = snl_attr_get_uint64 },
nlattr_add_u64(nw, PF_C_COUNTER, counter_u64_fetch(counters[i]));
nlattr_add_u64(nw, PF_C_COUNTER, pf_counter_u64_fetch(&counters[i]));