1 files changed, 119 insertions, 72 deletions

diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 83330a6cb242..184ea556f50e 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -261,7 +261,8 @@ static void tcp_ecn_accept_cwr(struct sock *sk, const struct sk_buff *skb)
 		 * cwnd may be very low (even just 1 packet), so we should ACK
 		 * immediately.
 		 */
-		inet_csk(sk)->icsk_ack.pending |= ICSK_ACK_NOW;
+		if (TCP_SKB_CB(skb)->seq != TCP_SKB_CB(skb)->end_seq)
+			inet_csk(sk)->icsk_ack.pending |= ICSK_ACK_NOW;
 	}
 }
 
@@ -517,7 +518,7 @@ EXPORT_SYMBOL(tcp_initialize_rcv_mss);
  *
  * The algorithm for RTT estimation w/o timestamps is based on
  * Dynamic Right-Sizing (DRS) by Wu Feng and Mike Fisk of LANL.
- * <http://public.lanl.gov/radiant/pubs.html#DRS>
+ * <https://public.lanl.gov/radiant/pubs.html#DRS>
  *
  * More detail on this code can be found at
  * <http://staff.psc.edu/jheffner/>,
@@ -870,12 +871,41 @@ __u32 tcp_init_cwnd(const struct tcp_sock *tp, const struct dst_entry *dst)
 	return min_t(__u32, cwnd, tp->snd_cwnd_clamp);
 }
 
+struct tcp_sacktag_state {
+	/* Timestamps for earliest and latest never-retransmitted segment
+	 * that was SACKed. RTO needs the earliest RTT to stay conservative,
+	 * but congestion control should still get an accurate delay signal.
+	 */
+	u64	first_sackt;
+	u64	last_sackt;
+	u32	reord;
+	u32	sack_delivered;
+	int	flag;
+	unsigned int mss_now;
+	struct rate_sample *rate;
+};
+
 /* Take a notice that peer is sending D-SACKs */
-static void tcp_dsack_seen(struct tcp_sock *tp)
+static u32 tcp_dsack_seen(struct tcp_sock *tp, u32 start_seq,
+			  u32 end_seq, struct tcp_sacktag_state *state)
 {
+	u32 seq_len, dup_segs = 1;
+
+	if (before(start_seq, end_seq)) {
+		seq_len = end_seq - start_seq;
+		if (seq_len > tp->mss_cache)
+			dup_segs = DIV_ROUND_UP(seq_len, tp->mss_cache);
+	}
+
 	tp->rx_opt.sack_ok |= TCP_DSACK_SEEN;
 	tp->rack.dsack_seen = 1;
-	tp->dsack_dups++;
+	tp->dsack_dups += dup_segs;
+
+	state->flag |= FLAG_DSACKING_ACK;
+	/* A spurious retransmission is delivered */
+	state->sack_delivered += dup_segs;
+
+	return dup_segs;
 }
 
 /* It's reordering when higher sequence was delivered (i.e. sacked) before
@@ -961,6 +991,15 @@ void tcp_skb_mark_lost_uncond_verify(struct tcp_sock *tp, struct sk_buff *skb)
 	}
 }
 
+/* Updates the delivered and delivered_ce counts */
+static void tcp_count_delivered(struct tcp_sock *tp, u32 delivered,
+				bool ece_ack)
+{
+	tp->delivered += delivered;
+	if (ece_ack)
+		tp->delivered_ce += delivered;
+}
+
 /* This procedure tags the retransmission queue when SACKs arrive.
  *
  * We have three tag bits: SACKED(S), RETRANS(R) and LOST(L).
@@ -1093,52 +1132,38 @@ static bool tcp_is_sackblock_valid(struct tcp_sock *tp, bool is_dsack,
 
 static bool tcp_check_dsack(struct sock *sk, const struct sk_buff *ack_skb,
 			    struct tcp_sack_block_wire *sp, int num_sacks,
-			    u32 prior_snd_una)
+			    u32 prior_snd_una, struct tcp_sacktag_state *state)
 {
 	struct tcp_sock *tp = tcp_sk(sk);
 	u32 start_seq_0 = get_unaligned_be32(&sp[0].start_seq);
 	u32 end_seq_0 = get_unaligned_be32(&sp[0].end_seq);
-	bool dup_sack = false;
+	u32 dup_segs;
 
 	if (before(start_seq_0, TCP_SKB_CB(ack_skb)->ack_seq)) {
-		dup_sack = true;
-		tcp_dsack_seen(tp);
 		NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPDSACKRECV);
 	} else if (num_sacks > 1) {
 		u32 end_seq_1 = get_unaligned_be32(&sp[1].end_seq);
 		u32 start_seq_1 = get_unaligned_be32(&sp[1].start_seq);
 
-		if (!after(end_seq_0, end_seq_1) &&
-		    !before(start_seq_0, start_seq_1)) {
-			dup_sack = true;
-			tcp_dsack_seen(tp);
-			NET_INC_STATS(sock_net(sk),
-					LINUX_MIB_TCPDSACKOFORECV);
-		}
+		if (after(end_seq_0, end_seq_1) || before(start_seq_0, start_seq_1))
+			return false;
+		NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPDSACKOFORECV);
+	} else {
+		return false;
 	}
 
+	dup_segs = tcp_dsack_seen(tp, start_seq_0, end_seq_0, state);
+	NET_ADD_STATS(sock_net(sk), LINUX_MIB_TCPDSACKRECVSEGS, dup_segs);
+
 	/* D-SACK for already forgotten data... Do dumb counting. */
-	if (dup_sack && tp->undo_marker && tp->undo_retrans > 0 &&
+	if (tp->undo_marker && tp->undo_retrans > 0 &&
 	    !after(end_seq_0, prior_snd_una) &&
 	    after(end_seq_0, tp->undo_marker))
-		tp->undo_retrans--;
+		tp->undo_retrans = max_t(int, 0, tp->undo_retrans - dup_segs);
 
-	return dup_sack;
+	return true;
 }
 
-struct tcp_sacktag_state {
-	u32	reord;
-	/* Timestamps for earliest and latest never-retransmitted segment
-	 * that was SACKed. RTO needs the earliest RTT to stay conservative,
-	 * but congestion control should still get an accurate delay signal.
-	 */
-	u64	first_sackt;
-	u64	last_sackt;
-	struct rate_sample *rate;
-	int	flag;
-	unsigned int mss_now;
-};
-
 /* Check if skb is fully within the SACK block. In presence of GSO skbs,
  * the incoming SACK may not exactly match but we can find smaller MSS
  * aligned portion of it that matches. Therefore we might need to fragment
@@ -1257,7 +1282,8 @@ static u8 tcp_sacktag_one(struct sock *sk,
 		sacked |= TCPCB_SACKED_ACKED;
 		state->flag |= FLAG_DATA_SACKED;
 		tp->sacked_out += pcount;
-		tp->delivered += pcount;  /* Out-of-order packets delivered */
+		/* Out-of-order packets delivered */
+		state->sack_delivered += pcount;
 
 		/* Lost marker hint past SACKed? Tweak RFC3517 cnt */
 		if (tp->lost_skb_hint &&
@@ -1680,11 +1706,7 @@ tcp_sacktag_write_queue(struct sock *sk, const struct sk_buff *ack_skb,
 		tcp_highest_sack_reset(sk);
 
 	found_dup_sack = tcp_check_dsack(sk, ack_skb, sp_wire,
-					 num_sacks, prior_snd_una);
-	if (found_dup_sack) {
-		state->flag |= FLAG_DSACKING_ACK;
-		tp->delivered++; /* A spurious retransmission is delivered */
-	}
+					 num_sacks, prior_snd_una, state);
 
 	/* Eliminate too old ACKs, but take into
 	 * account more or less fresh ones, they can
@@ -1892,7 +1914,7 @@ static void tcp_check_reno_reordering(struct sock *sk, const int addend)
 
 /* Emulate SACKs for SACKless connection: account for a new dupack. */
 
-static void tcp_add_reno_sack(struct sock *sk, int num_dupack)
+static void tcp_add_reno_sack(struct sock *sk, int num_dupack, bool ece_ack)
 {
 	if (num_dupack) {
 		struct tcp_sock *tp = tcp_sk(sk);
@@ -1903,20 +1925,21 @@ static void tcp_add_reno_sack(struct sock *sk, int num_dupack)
 		tcp_check_reno_reordering(sk, 0);
 		delivered = tp->sacked_out - prior_sacked;
 		if (delivered > 0)
-			tp->delivered += delivered;
+			tcp_count_delivered(tp, delivered, ece_ack);
 		tcp_verify_left_out(tp);
 	}
 }
 
 /* Account for ACK, ACKing some data in Reno Recovery phase. */
 
-static void tcp_remove_reno_sacks(struct sock *sk, int acked)
+static void tcp_remove_reno_sacks(struct sock *sk, int acked, bool ece_ack)
 {
 	struct tcp_sock *tp = tcp_sk(sk);
 
 	if (acked > 0) {
 		/* One ACK acked hole. The rest eat duplicate ACKs. */
-		tp->delivered += max_t(int, acked - tp->sacked_out, 1);
+		tcp_count_delivered(tp, max_t(int, acked - tp->sacked_out, 1),
+				    ece_ack);
 		if (acked - 1 >= tp->sacked_out)
 			tp->sacked_out = 0;
 		else
@@ -2696,7 +2719,7 @@ static void tcp_process_loss(struct sock *sk, int flag, int num_dupack,
 		 * delivered. Lower inflight to clock out (re)tranmissions.
 		 */
 		if (after(tp->snd_nxt, tp->high_seq) && num_dupack)
-			tcp_add_reno_sack(sk, num_dupack);
+			tcp_add_reno_sack(sk, num_dupack, flag & FLAG_ECE);
 		else if (flag & FLAG_SND_UNA_ADVANCED)
 			tcp_reset_reno_sack(tp);
 	}
@@ -2778,6 +2801,7 @@ static void tcp_fastretrans_alert(struct sock *sk, const u32 prior_snd_una,
 	struct inet_connection_sock *icsk = inet_csk(sk);
 	struct tcp_sock *tp = tcp_sk(sk);
 	int fast_rexmit = 0, flag = *ack_flag;
+	bool ece_ack = flag & FLAG_ECE;
 	bool do_lost = num_dupack || ((flag & FLAG_DATA_SACKED) &&
 				      tcp_force_fast_retransmit(sk));
 
@@ -2786,7 +2810,7 @@ static void tcp_fastretrans_alert(struct sock *sk, const u32 prior_snd_una,
 
 	/* Now state machine starts.
 	 * A. ECE, hence prohibit cwnd undoing, the reduction is required. */
-	if (flag & FLAG_ECE)
+	if (ece_ack)
 		tp->prior_ssthresh = 0;
 
 	/* B. In all the states check for reneging SACKs. */
@@ -2827,7 +2851,7 @@ static void tcp_fastretrans_alert(struct sock *sk, const u32 prior_snd_una,
 	case TCP_CA_Recovery:
 		if (!(flag & FLAG_SND_UNA_ADVANCED)) {
 			if (tcp_is_reno(tp))
-				tcp_add_reno_sack(sk, num_dupack);
+				tcp_add_reno_sack(sk, num_dupack, ece_ack);
 		} else {
 			if (tcp_try_undo_partial(sk, prior_snd_una))
 				return;
@@ -2852,7 +2876,7 @@ static void tcp_fastretrans_alert(struct sock *sk, const u32 prior_snd_una,
 		if (tcp_is_reno(tp)) {
 			if (flag & FLAG_SND_UNA_ADVANCED)
 				tcp_reset_reno_sack(tp);
-			tcp_add_reno_sack(sk, num_dupack);
+			tcp_add_reno_sack(sk, num_dupack, ece_ack);
 		}
 
 		if (icsk->icsk_ca_state <= TCP_CA_Disorder)
@@ -2876,7 +2900,7 @@ static void tcp_fastretrans_alert(struct sock *sk, const u32 prior_snd_una,
 		}
 
 		/* Otherwise enter Recovery state */
-		tcp_enter_recovery(sk, (flag & FLAG_ECE));
+		tcp_enter_recovery(sk, ece_ack);
 		fast_rexmit = 1;
 	}
 
@@ -2926,6 +2950,8 @@ static bool tcp_ack_update_rtt(struct sock *sk, const int flag,
 		u32 delta = tcp_time_stamp(tp) - tp->rx_opt.rcv_tsecr;
 
 		if (likely(delta < INT_MAX / (USEC_PER_SEC / TCP_TS_HZ))) {
+			if (!delta)
+				delta = 1;
 			seq_rtt_us = delta * (USEC_PER_SEC / TCP_TS_HZ);
 			ca_rtt_us = seq_rtt_us;
 		}
@@ -3052,7 +3078,7 @@ static void tcp_ack_tstamp(struct sock *sk, struct sk_buff *skb,
  */
 static int tcp_clean_rtx_queue(struct sock *sk, u32 prior_fack,
 			       u32 prior_snd_una,
-			       struct tcp_sacktag_state *sack)
+			       struct tcp_sacktag_state *sack, bool ece_ack)
 {
 	const struct inet_connection_sock *icsk = inet_csk(sk);
 	u64 first_ackt, last_ackt;
@@ -3077,8 +3103,6 @@ static int tcp_clean_rtx_queue(struct sock *sk, u32 prior_fack,
 		u8 sacked = scb->sacked;
 		u32 acked_pcount;
 
-		tcp_ack_tstamp(sk, skb, prior_snd_una);
-
 		/* Determine how many packets and what bytes were acked, tso and else */
 		if (after(scb->end_seq, tp->snd_una)) {
 			if (tcp_skb_pcount(skb) == 1 ||
@@ -3113,7 +3137,7 @@ static int tcp_clean_rtx_queue(struct sock *sk, u32 prior_fack,
 		if (sacked & TCPCB_SACKED_ACKED) {
 			tp->sacked_out -= acked_pcount;
 		} else if (tcp_is_sack(tp)) {
-			tp->delivered += acked_pcount;
+			tcp_count_delivered(tp, acked_pcount, ece_ack);
 			if (!tcp_skb_spurious_retrans(tp, skb))
 				tcp_rack_advance(tp, sacked, scb->end_seq,
 						 tcp_skb_timestamp_us(skb));
@@ -3142,6 +3166,8 @@ static int tcp_clean_rtx_queue(struct sock *sk, u32 prior_fack,
 		if (!fully_acked)
 			break;
 
+		tcp_ack_tstamp(sk, skb, prior_snd_una);
+
 		next = skb_rb_next(skb);
 		if (unlikely(skb == tp->retransmit_skb_hint))
 			tp->retransmit_skb_hint = NULL;
@@ -3157,8 +3183,11 @@ static int tcp_clean_rtx_queue(struct sock *sk, u32 prior_fack,
 	if (likely(between(tp->snd_up, prior_snd_una, tp->snd_una)))
 		tp->snd_up = tp->snd_una;
 
-	if (skb && (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_ACKED))
-		flag |= FLAG_SACK_RENEGING;
+	if (skb) {
+		tcp_ack_tstamp(sk, skb, prior_snd_una);
+		if (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_ACKED)
+			flag |= FLAG_SACK_RENEGING;
+	}
 
 	if (likely(first_ackt) && !(flag & FLAG_RETRANS_DATA_ACKED)) {
 		seq_rtt_us = tcp_stamp_us_delta(tp->tcp_mstamp, first_ackt);
@@ -3190,7 +3219,7 @@ static int tcp_clean_rtx_queue(struct sock *sk, u32 prior_fack,
 		}
 
 		if (tcp_is_reno(tp)) {
-			tcp_remove_reno_sacks(sk, pkts_acked);
+			tcp_remove_reno_sacks(sk, pkts_acked, ece_ack);
 
 			/* If any of the cumulatively ACKed segments was
 			 * retransmitted, non-SACK case cannot confirm that
@@ -3487,10 +3516,8 @@ static void tcp_replace_ts_recent(struct tcp_sock *tp, u32 seq)
 	}
 }
 
-/* This routine deals with acks during a TLP episode.
- * We mark the end of a TLP episode on receiving TLP dupack or when
- * ack is after tlp_high_seq.
- * Ref: loss detection algorithm in draft-dukkipati-tcpm-tcp-loss-probe.
+/* This routine deals with acks during a TLP episode and ends an episode by
+ * resetting tlp_high_seq. Ref: TLP algorithm in draft-ietf-tcpm-rack
  */
 static void tcp_process_tlp_ack(struct sock *sk, u32 ack, int flag)
 {
@@ -3499,7 +3526,10 @@ static void tcp_process_tlp_ack(struct sock *sk, u32 ack, int flag)
 	if (before(ack, tp->tlp_high_seq))
 		return;
 
-	if (flag & FLAG_DSACKING_ACK) {
+	if (!tp->tlp_retrans) {
+		/* TLP of new data has been acknowledged */
+		tp->tlp_high_seq = 0;
+	} else if (flag & FLAG_DSACKING_ACK) {
 		/* This DSACK means original and TLP probe arrived; no loss */
 		tp->tlp_high_seq = 0;
 	} else if (after(ack, tp->tlp_high_seq)) {
@@ -3557,10 +3587,9 @@ static u32 tcp_newly_delivered(struct sock *sk, u32 prior_delivered, int flag)
 
 	delivered = tp->delivered - prior_delivered;
 	NET_ADD_STATS(net, LINUX_MIB_TCPDELIVERED, delivered);
-	if (flag & FLAG_ECE) {
-		tp->delivered_ce += delivered;
+	if (flag & FLAG_ECE)
 		NET_ADD_STATS(net, LINUX_MIB_TCPDELIVEREDCE, delivered);
-	}
+
 	return delivered;
 }
 
@@ -3584,6 +3613,7 @@ static int tcp_ack(struct sock *sk, const struct sk_buff *skb, int flag)
 
 	sack_state.first_sackt = 0;
 	sack_state.rate = &rs;
+	sack_state.sack_delivered = 0;
 
 	/* We very likely will need to access rtx queue. */
 	prefetch(sk->tcp_rtx_queue.rb_node);
@@ -3659,12 +3689,25 @@ static int tcp_ack(struct sock *sk, const struct sk_buff *skb, int flag)
 			ack_ev_flags |= CA_ACK_ECE;
 		}
 
+		if (sack_state.sack_delivered)
+			tcp_count_delivered(tp, sack_state.sack_delivered,
+					    flag & FLAG_ECE);
+
 		if (flag & FLAG_WIN_UPDATE)
 			ack_ev_flags |= CA_ACK_WIN_UPDATE;
 
 		tcp_in_ack_event(sk, ack_ev_flags);
 	}
 
+	/* This is a deviation from RFC3168 since it states that:
+	 * "When the TCP data sender is ready to set the CWR bit after reducing
+	 * the congestion window, it SHOULD set the CWR bit only on the first
+	 * new data packet that it transmits."
+	 * We accept CWR on pure ACKs to be more robust
+	 * with widely-deployed TCP implementations that do this.
+	 */
+	tcp_ecn_accept_cwr(sk, skb);
+
 	/* We passed data and got it acked, remove any soft error
 	 * log. Something worked...
 	 */
@@ -3675,7 +3718,8 @@ static int tcp_ack(struct sock *sk, const struct sk_buff *skb, int flag)
 		goto no_queue;
 
 	/* See if we can take anything off of the retransmit queue. */
-	flag |= tcp_clean_rtx_queue(sk, prior_fack, prior_snd_una, &sack_state);
+	flag |= tcp_clean_rtx_queue(sk, prior_fack, prior_snd_una, &sack_state,
+				    flag & FLAG_ECE);
 
 	tcp_rack_update_reo_wnd(sk, &rs);
 
@@ -4416,7 +4460,6 @@ static void tcp_sack_remove(struct tcp_sock *tp)
 /**
  * tcp_try_coalesce - try to merge skb to prior one
  * @sk: socket
- * @dest: destination queue
  * @to: prior buffer
  * @from: buffer to add in queue
  * @fragstolen: pointer to boolean
@@ -4572,6 +4615,7 @@ static void tcp_data_queue_ofo(struct sock *sk, struct sk_buff *skb)
 
 	if (unlikely(tcp_try_rmem_schedule(sk, skb, skb->truesize))) {
 		NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPOFODROP);
+		sk->sk_data_ready(sk);
 		tcp_drop(sk, skb);
 		return;
 	}
@@ -4605,7 +4649,11 @@ static void tcp_data_queue_ofo(struct sock *sk, struct sk_buff *skb)
 	if (tcp_ooo_try_coalesce(sk, tp->ooo_last_skb,
 				 skb, &fragstolen)) {
 coalesce_done:
-		tcp_grow_window(sk, skb);
+		/* For non sack flows, do not grow window to force DUPACK
+		 * and trigger fast retransmit.
+		 */
+		if (tcp_is_sack(tp))
+			tcp_grow_window(sk, skb);
 		kfree_skb_partial(skb, fragstolen);
 		skb = NULL;
 		goto add_sack;
@@ -4689,7 +4737,11 @@ add_sack:
 		tcp_sack_new_ofo_skb(sk, seq, end_seq);
 end:
 	if (skb) {
-		tcp_grow_window(sk, skb);
+		/* For non sack flows, do not grow window to force DUPACK
+		 * and trigger fast retransmit.
+		 */
+		if (tcp_is_sack(tp))
+			tcp_grow_window(sk, skb);
 		skb_condense(skb);
 		skb_set_owner_r(skb, sk);
 	}
@@ -4792,8 +4844,6 @@ static void tcp_data_queue(struct sock *sk, struct sk_buff *skb)
 	skb_dst_drop(skb);
 	__skb_pull(skb, tcp_hdr(skb)->doff * 4);
 
-	tcp_ecn_accept_cwr(sk, skb);
-
 	tp->rx_opt.dsack = 0;
 
 	/*  Queue data for delivery to the user.
@@ -4812,6 +4862,7 @@ queue_and_out:
 			sk_forced_mem_schedule(sk, skb->truesize);
 		else if (tcp_try_rmem_schedule(sk, skb, skb->truesize)) {
 			NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPRCVQDROP);
+			sk->sk_data_ready(sk);
 			goto drop;
 		}
 
@@ -6470,7 +6521,6 @@ static void tcp_openreq_init(struct request_sock *req,
 	struct inet_request_sock *ireq = inet_rsk(req);
 
 	req->rsk_rcv_wnd = 0;		/* So that tcp_send_synack() knows! */
-	req->cookie_ts = 0;
 	tcp_rsk(req)->rcv_isn = TCP_SKB_CB(skb)->seq;
 	tcp_rsk(req)->rcv_nxt = TCP_SKB_CB(skb)->seq + 1;
 	tcp_rsk(req)->snt_synack = 0;
@@ -6625,6 +6675,7 @@ int tcp_conn_request(struct request_sock_ops *rsk_ops,
 	if (!req)
 		goto drop;
 
+	req->syncookie = want_cookie;
 	tcp_rsk(req)->af_specific = af_ops;
 	tcp_rsk(req)->ts_off = 0;
 #if IS_ENABLED(CONFIG_MPTCP)
@@ -6652,9 +6703,6 @@ int tcp_conn_request(struct request_sock_ops *rsk_ops,
 
 	af_ops->init_req(req, sk, skb);
 
-	if (IS_ENABLED(CONFIG_MPTCP) && want_cookie)
-		tcp_rsk(req)->is_mptcp = 0;
-
 	if (security_inet_conn_request(sk, skb, req))
 		goto drop_and_free;
 
@@ -6690,7 +6738,6 @@ int tcp_conn_request(struct request_sock_ops *rsk_ops,
 
 	if (want_cookie) {
 		isn = cookie_init_sequence(af_ops, sk, skb, &req->mss);
-		req->cookie_ts = tmp_opt.tstamp_ok;
 		if (!tmp_opt.tstamp_ok)
 			inet_rsk(req)->ecn_ok = 0;
 	}