BBR_PROBE_RTT
case BBR_PROBE_RTT:
if (bbr->prev_ca_state < TCP_CA_Recovery && bbr->mode != BBR_PROBE_RTT)
else if (bbr->mode == BBR_PROBE_RTT)
if (bbr->mode == BBR_PROBE_RTT) /* drain queue, refresh min_rtt */
!bbr->idle_restart && bbr->mode != BBR_PROBE_RTT) {
bbr->mode = BBR_PROBE_RTT; /* dip, drain queue */
if (bbr->mode == BBR_PROBE_RTT) {