+ /*
+ * On AWDL interface, the initial RTT measurement on SYN
+ * can be wrong due to peer caching. Avoid the first RTT
+ * measurement as it might skew up the RTO.
+ * <rdar://problem/28739046>
+ */
+ if (tp->t_inpcb->inp_last_outifp != NULL &&
+ (tp->t_inpcb->inp_last_outifp->if_eflags & IFEF_AWDL) &&
+ th_ack == tp->iss + 1)
+ return;
+