Function tcp_timer_rexmt

freebsd/netinet/tcp_timer.c:609–890

}

void
tcp_timer_rexmt(void * xtp)
{
	struct tcpcb *tp = xtp;
	CURVNET_SET(tp->t_vnet);
	int rexmt;
	struct inpcb *inp;
	struct epoch_tracker et;
	bool isipv6;
#ifdef TCPDEBUG
	int ostate;

	ostate = tp->t_state;
#endif
	inp = tp->t_inpcb;
	KASSERT(inp != NULL, ("%s: tp %p tp->t_inpcb == NULL", __func__, tp));
	INP_WLOCK(inp);
	if (callout_pending(&tp->t_timers->tt_rexmt) ||
	    !callout_active(&tp->t_timers->tt_rexmt)) {
		INP_WUNLOCK(inp);
		CURVNET_RESTORE();
		return;
	}
	callout_deactivate(&tp->t_timers->tt_rexmt);
	if ((inp->inp_flags & INP_DROPPED) != 0) {
		INP_WUNLOCK(inp);
		CURVNET_RESTORE();
		return;
	}
	KASSERT((tp->t_timers->tt_flags & TT_STOPPED) == 0,
		("%s: tp %p tcpcb can't be stopped here", __func__, tp));
	tcp_free_sackholes(tp);
	TCP_LOG_EVENT(tp, NULL, NULL, NULL, TCP_LOG_RTO, 0, 0, NULL, false);
	if (tp->t_fb->tfb_tcp_rexmit_tmr) {
		/* The stack has a timer action too. */
		(*tp->t_fb->tfb_tcp_rexmit_tmr)(tp);
	}
	/*
	 * Retransmission timer went off.  Message has not
	 * been acked within retransmit interval.  Back off
	 * to a longer retransmit interval and retransmit one segment.
	 */
	if (++tp->t_rxtshift > TCP_MAXRXTSHIFT) {
		tp->t_rxtshift = TCP_MAXRXTSHIFT;
		TCPSTAT_INC(tcps_timeoutdrop);
		if (inp->inp_flags & (INP_TIMEWAIT | INP_DROPPED)) {
			tcp_inpinfo_lock_del(inp, tp);
			goto out;
		}
		NET_EPOCH_ENTER(et);
		tp = tcp_drop(tp, ETIMEDOUT);
		NET_EPOCH_EXIT(et);
		tcp_inpinfo_lock_del(inp, tp);
		goto out;
	}
	if (tp->t_state == TCPS_SYN_SENT) {
		/*
		 * If the SYN was retransmitted, indicate CWND to be