V_tcp_pmtud_blackhole_mss
if (tp->t_maxseg > V_tcp_pmtud_blackhole_mss) {
tp->t_maxseg = V_tcp_pmtud_blackhole_mss;
if (tp->t_maxseg > V_tcp_pmtud_blackhole_mss) {
tp->t_maxseg = V_tcp_pmtud_blackhole_mss;
if (tp->t_maxseg > V_tcp_pmtud_blackhole_mss)
V_tcp_pmtud_blackhole_mss > V_tcp_mssdflt)
if (tp->t_maxseg > V_tcp_pmtud_blackhole_mss &&
V_tcp_pmtud_blackhole_mss > V_tcp_mssdflt) {
tp->t_maxseg = V_tcp_pmtud_blackhole_mss;