Orange Pi5 kernel

^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300   1) // SPDX-License-Identifier: GPL-2.0
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300   2) #include <linux/tcp.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300   3) #include <net/tcp.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300   4) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300   5) static bool tcp_rack_sent_after(u64 t1, u64 t2, u32 seq1, u32 seq2)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300   6) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300   7) 	return t1 > t2 || (t1 == t2 && after(seq1, seq2));
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300   8) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300   9) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  10) static u32 tcp_rack_reo_wnd(const struct sock *sk)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  11) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  12) 	struct tcp_sock *tp = tcp_sk(sk);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  13) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  14) 	if (!tp->reord_seen) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  15) 		/* If reordering has not been observed, be aggressive during
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  16) 		 * the recovery or starting the recovery by DUPACK threshold.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  17) 		 */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  18) 		if (inet_csk(sk)->icsk_ca_state >= TCP_CA_Recovery)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  19) 			return 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  20) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  21) 		if (tp->sacked_out >= tp->reordering &&
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  22) 		    !(sock_net(sk)->ipv4.sysctl_tcp_recovery & TCP_RACK_NO_DUPTHRESH))
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  23) 			return 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  24) 	}
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  25) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  26) 	/* To be more reordering resilient, allow min_rtt/4 settling delay.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  27) 	 * Use min_rtt instead of the smoothed RTT because reordering is
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  28) 	 * often a path property and less related to queuing or delayed ACKs.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  29) 	 * Upon receiving DSACKs, linearly increase the window up to the
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  30) 	 * smoothed RTT.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  31) 	 */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  32) 	return min((tcp_min_rtt(tp) >> 2) * tp->rack.reo_wnd_steps,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  33) 		   tp->srtt_us >> 3);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  34) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  35) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  36) s32 tcp_rack_skb_timeout(struct tcp_sock *tp, struct sk_buff *skb, u32 reo_wnd)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  37) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  38) 	return tp->rack.rtt_us + reo_wnd -
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  39) 	       tcp_stamp_us_delta(tp->tcp_mstamp, tcp_skb_timestamp_us(skb));
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  40) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  41) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  42) /* RACK loss detection (IETF draft draft-ietf-tcpm-rack-01):
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  43)  *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  44)  * Marks a packet lost, if some packet sent later has been (s)acked.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  45)  * The underlying idea is similar to the traditional dupthresh and FACK
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  46)  * but they look at different metrics:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  47)  *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  48)  * dupthresh: 3 OOO packets delivered (packet count)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  49)  * FACK: sequence delta to highest sacked sequence (sequence space)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  50)  * RACK: sent time delta to the latest delivered packet (time domain)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  51)  *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  52)  * The advantage of RACK is it applies to both original and retransmitted
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  53)  * packet and therefore is robust against tail losses. Another advantage
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  54)  * is being more resilient to reordering by simply allowing some
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  55)  * "settling delay", instead of tweaking the dupthresh.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  56)  *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  57)  * When tcp_rack_detect_loss() detects some packets are lost and we
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  58)  * are not already in the CA_Recovery state, either tcp_rack_reo_timeout()
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  59)  * or tcp_time_to_recover()'s "Trick#1: the loss is proven" code path will
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  60)  * make us enter the CA_Recovery state.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  61)  */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  62) static void tcp_rack_detect_loss(struct sock *sk, u32 *reo_timeout)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  63) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  64) 	struct tcp_sock *tp = tcp_sk(sk);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  65) 	struct sk_buff *skb, *n;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  66) 	u32 reo_wnd;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  67) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  68) 	*reo_timeout = 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  69) 	reo_wnd = tcp_rack_reo_wnd(sk);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  70) 	list_for_each_entry_safe(skb, n, &tp->tsorted_sent_queue,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  71) 				 tcp_tsorted_anchor) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  72) 		struct tcp_skb_cb *scb = TCP_SKB_CB(skb);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  73) 		s32 remaining;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  74) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  75) 		/* Skip ones marked lost but not yet retransmitted */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  76) 		if ((scb->sacked & TCPCB_LOST) &&
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  77) 		    !(scb->sacked & TCPCB_SACKED_RETRANS))
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  78) 			continue;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  79) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  80) 		if (!tcp_rack_sent_after(tp->rack.mstamp,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  81) 					 tcp_skb_timestamp_us(skb),
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  82) 					 tp->rack.end_seq, scb->end_seq))
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  83) 			break;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  84) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  85) 		/* A packet is lost if it has not been s/acked beyond
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  86) 		 * the recent RTT plus the reordering window.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  87) 		 */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  88) 		remaining = tcp_rack_skb_timeout(tp, skb, reo_wnd);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  89) 		if (remaining <= 0) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  90) 			tcp_mark_skb_lost(sk, skb);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  91) 			list_del_init(&skb->tcp_tsorted_anchor);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  92) 		} else {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  93) 			/* Record maximum wait time */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  94) 			*reo_timeout = max_t(u32, *reo_timeout, remaining);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  95) 		}
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  96) 	}
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  97) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  98) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  99) bool tcp_rack_mark_lost(struct sock *sk)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 100) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 101) 	struct tcp_sock *tp = tcp_sk(sk);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 102) 	u32 timeout;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 103) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 104) 	if (!tp->rack.advanced)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 105) 		return false;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 106) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 107) 	/* Reset the advanced flag to avoid unnecessary queue scanning */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 108) 	tp->rack.advanced = 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 109) 	tcp_rack_detect_loss(sk, &timeout);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 110) 	if (timeout) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 111) 		timeout = usecs_to_jiffies(timeout) + TCP_TIMEOUT_MIN;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 112) 		inet_csk_reset_xmit_timer(sk, ICSK_TIME_REO_TIMEOUT,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 113) 					  timeout, inet_csk(sk)->icsk_rto);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 114) 	}
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 115) 	return !!timeout;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 116) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 117) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 118) /* Record the most recently (re)sent time among the (s)acked packets
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 119)  * This is "Step 3: Advance RACK.xmit_time and update RACK.RTT" from
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 120)  * draft-cheng-tcpm-rack-00.txt
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 121)  */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 122) void tcp_rack_advance(struct tcp_sock *tp, u8 sacked, u32 end_seq,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 123) 		      u64 xmit_time)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 124) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 125) 	u32 rtt_us;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 126) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 127) 	rtt_us = tcp_stamp_us_delta(tp->tcp_mstamp, xmit_time);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 128) 	if (rtt_us < tcp_min_rtt(tp) && (sacked & TCPCB_RETRANS)) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 129) 		/* If the sacked packet was retransmitted, it's ambiguous
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 130) 		 * whether the retransmission or the original (or the prior
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 131) 		 * retransmission) was sacked.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 132) 		 *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 133) 		 * If the original is lost, there is no ambiguity. Otherwise
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 134) 		 * we assume the original can be delayed up to aRTT + min_rtt.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 135) 		 * the aRTT term is bounded by the fast recovery or timeout,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 136) 		 * so it's at least one RTT (i.e., retransmission is at least
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 137) 		 * an RTT later).
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 138) 		 */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 139) 		return;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 140) 	}
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 141) 	tp->rack.advanced = 1;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 142) 	tp->rack.rtt_us = rtt_us;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 143) 	if (tcp_rack_sent_after(xmit_time, tp->rack.mstamp,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 144) 				end_seq, tp->rack.end_seq)) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 145) 		tp->rack.mstamp = xmit_time;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 146) 		tp->rack.end_seq = end_seq;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 147) 	}
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 148) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 149) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 150) /* We have waited long enough to accommodate reordering. Mark the expired
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 151)  * packets lost and retransmit them.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 152)  */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 153) void tcp_rack_reo_timeout(struct sock *sk)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 154) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 155) 	struct tcp_sock *tp = tcp_sk(sk);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 156) 	u32 timeout, prior_inflight;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 157) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 158) 	prior_inflight = tcp_packets_in_flight(tp);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 159) 	tcp_rack_detect_loss(sk, &timeout);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 160) 	if (prior_inflight != tcp_packets_in_flight(tp)) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 161) 		if (inet_csk(sk)->icsk_ca_state != TCP_CA_Recovery) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 162) 			tcp_enter_recovery(sk, false);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 163) 			if (!inet_csk(sk)->icsk_ca_ops->cong_control)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 164) 				tcp_cwnd_reduction(sk, 1, 0);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 165) 		}
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 166) 		tcp_xmit_retransmit_queue(sk);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 167) 	}
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 168) 	if (inet_csk(sk)->icsk_pending != ICSK_TIME_RETRANS)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 169) 		tcp_rearm_rto(sk);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 170) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 171) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 172) /* Updates the RACK's reo_wnd based on DSACK and no. of recoveries.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 173)  *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 174)  * If DSACK is received, increment reo_wnd by min_rtt/4 (upper bounded
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 175)  * by srtt), since there is possibility that spurious retransmission was
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 176)  * due to reordering delay longer than reo_wnd.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 177)  *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 178)  * Persist the current reo_wnd value for TCP_RACK_RECOVERY_THRESH (16)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 179)  * no. of successful recoveries (accounts for full DSACK-based loss
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 180)  * recovery undo). After that, reset it to default (min_rtt/4).
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 181)  *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 182)  * At max, reo_wnd is incremented only once per rtt. So that the new
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 183)  * DSACK on which we are reacting, is due to the spurious retx (approx)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 184)  * after the reo_wnd has been updated last time.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 185)  *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 186)  * reo_wnd is tracked in terms of steps (of min_rtt/4), rather than
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 187)  * absolute value to account for change in rtt.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 188)  */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 189) void tcp_rack_update_reo_wnd(struct sock *sk, struct rate_sample *rs)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 190) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 191) 	struct tcp_sock *tp = tcp_sk(sk);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 192) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 193) 	if (sock_net(sk)->ipv4.sysctl_tcp_recovery & TCP_RACK_STATIC_REO_WND ||
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 194) 	    !rs->prior_delivered)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 195) 		return;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 196) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 197) 	/* Disregard DSACK if a rtt has not passed since we adjusted reo_wnd */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 198) 	if (before(rs->prior_delivered, tp->rack.last_delivered))
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 199) 		tp->rack.dsack_seen = 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 200) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 201) 	/* Adjust the reo_wnd if update is pending */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 202) 	if (tp->rack.dsack_seen) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 203) 		tp->rack.reo_wnd_steps = min_t(u32, 0xFF,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 204) 					       tp->rack.reo_wnd_steps + 1);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 205) 		tp->rack.dsack_seen = 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 206) 		tp->rack.last_delivered = tp->delivered;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 207) 		tp->rack.reo_wnd_persist = TCP_RACK_RECOVERY_THRESH;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 208) 	} else if (!tp->rack.reo_wnd_persist) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 209) 		tp->rack.reo_wnd_steps = 1;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 210) 	}
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 211) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 212) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 213) /* RFC6582 NewReno recovery for non-SACK connection. It simply retransmits
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 214)  * the next unacked packet upon receiving
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 215)  * a) three or more DUPACKs to start the fast recovery
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 216)  * b) an ACK acknowledging new data during the fast recovery.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 217)  */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 218) void tcp_newreno_mark_lost(struct sock *sk, bool snd_una_advanced)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 219) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 220) 	const u8 state = inet_csk(sk)->icsk_ca_state;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 221) 	struct tcp_sock *tp = tcp_sk(sk);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 222) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 223) 	if ((state < TCP_CA_Recovery && tp->sacked_out >= tp->reordering) ||
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 224) 	    (state == TCP_CA_Recovery && snd_una_advanced)) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 225) 		struct sk_buff *skb = tcp_rtx_queue_head(sk);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 226) 		u32 mss;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 227) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 228) 		if (TCP_SKB_CB(skb)->sacked & TCPCB_LOST)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 229) 			return;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 230) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 231) 		mss = tcp_skb_mss(skb);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 232) 		if (tcp_skb_pcount(skb) > 1 && skb->len > mss)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 233) 			tcp_fragment(sk, TCP_FRAG_IN_RTX_QUEUE, skb,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 234) 				     mss, mss, GFP_ATOMIC);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 235) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 236) 		tcp_mark_skb_lost(sk, skb);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 237) 	}
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 238) }