PF_RT_PROB
snl_add_msg_attr_u32(nw, PF_RT_PROB, r->prob);
{ .type = PF_RT_PROB, .off = _OUT(r.prob), .cb = snl_attr_get_uint32 },
{ .type = PF_RT_PROB, .off = _OUT(prob), .cb = nlattr_get_uint32 },
nlattr_add_u32(nw, PF_RT_PROB, rule->prob);