5 files changed, 21 insertions, 6 deletions

diff --git a/net/ipv4/tcp_illinois.c b/net/ipv4/tcp_illinois.c
index 4adc47c55351..b2b2256d3b84 100644
--- a/net/ipv4/tcp_illinois.c
+++ b/net/ipv4/tcp_illinois.c
@@ -90,6 +90,9 @@ static void tcp_illinois_acked(struct sock *sk, u32 pkts_acked, ktime_t last)
 
 	ca->acked = pkts_acked;
 
+	if (ktime_equal(last, net_invalid_timestamp()))
+		return;
+
 	rtt = ktime_to_us(net_timedelta(last));
 
 	/* ignore bogus values, this prevents wraparound in alpha math */
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index d6d0f9b6cdc6..69f9f1ef3ef6 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -953,7 +953,7 @@ tcp_sacktag_write_queue(struct sock *sk, struct sk_buff *ack_skb, u32 prior_snd_
 	int prior_fackets;
 	u32 lost_retrans = 0;
 	int flag = 0;
-	int dup_sack = 0;
+	int found_dup_sack = 0;
 	int cached_fack_count;
 	int i;
 	int first_sack_index;
@@ -964,20 +964,20 @@ tcp_sacktag_write_queue(struct sock *sk, struct sk_buff *ack_skb, u32 prior_snd_
 
 	/* Check for D-SACK. */
 	if (before(ntohl(sp[0].start_seq), TCP_SKB_CB(ack_skb)->ack_seq)) {
-		dup_sack = 1;
+		found_dup_sack = 1;
 		tp->rx_opt.sack_ok |= 4;
 		NET_INC_STATS_BH(LINUX_MIB_TCPDSACKRECV);
 	} else if (num_sacks > 1 &&
 			!after(ntohl(sp[0].end_seq), ntohl(sp[1].end_seq)) &&
 			!before(ntohl(sp[0].start_seq), ntohl(sp[1].start_seq))) {
-		dup_sack = 1;
+		found_dup_sack = 1;
 		tp->rx_opt.sack_ok |= 4;
 		NET_INC_STATS_BH(LINUX_MIB_TCPDSACKOFORECV);
 	}
 
 	/* D-SACK for already forgotten data...
 	 * Do dumb counting. */
-	if (dup_sack &&
+	if (found_dup_sack &&
 			!after(ntohl(sp[0].end_seq), prior_snd_una) &&
 			after(ntohl(sp[0].end_seq), tp->undo_marker))
 		tp->undo_retrans--;
@@ -1058,6 +1058,7 @@ tcp_sacktag_write_queue(struct sock *sk, struct sk_buff *ack_skb, u32 prior_snd_
 		__u32 start_seq = ntohl(sp->start_seq);
 		__u32 end_seq = ntohl(sp->end_seq);
 		int fack_count;
+		int dup_sack = (found_dup_sack && (i == first_sack_index));
 
 		skb = cached_skb;
 		fack_count = cached_fack_count;
@@ -2409,7 +2410,7 @@ static int tcp_clean_rtx_queue(struct sock *sk, __s32 *seq_rtt_p)
 	int acked = 0;
 	int prior_packets = tp->packets_out;
 	__s32 seq_rtt = -1;
-	ktime_t last_ackt = ktime_set(0,0);
+	ktime_t last_ackt = net_invalid_timestamp();
 
 	while ((skb = tcp_write_queue_head(sk)) &&
 	       skb != tcp_send_head(sk)) {
@@ -2487,6 +2488,10 @@ static int tcp_clean_rtx_queue(struct sock *sk, __s32 *seq_rtt_p)
 		tcp_ack_update_rtt(sk, acked, seq_rtt);
 		tcp_ack_packets_out(sk);
 
+		/* Is the ACK triggering packet unambiguous? */
+		if (acked & FLAG_RETRANS_DATA_ACKED)
+			last_ackt = net_invalid_timestamp();
+
 		if (ca_ops->pkts_acked)
 			ca_ops->pkts_acked(sk, pkts_acked, last_ackt);
 	}
diff --git a/net/ipv4/tcp_lp.c b/net/ipv4/tcp_lp.c
index 43294ad9f63e..e49836ce012e 100644
--- a/net/ipv4/tcp_lp.c
+++ b/net/ipv4/tcp_lp.c
@@ -266,7 +266,8 @@ static void tcp_lp_pkts_acked(struct sock *sk, u32 num_acked, ktime_t last)
 	struct tcp_sock *tp = tcp_sk(sk);
 	struct lp *lp = inet_csk_ca(sk);
 
-	tcp_lp_rtt_sample(sk,  ktime_to_us(net_timedelta(last)));
+	if (!ktime_equal(last, net_invalid_timestamp()))
+		tcp_lp_rtt_sample(sk,  ktime_to_us(net_timedelta(last)));
 
 	/* calc inference */
 	if (tcp_time_stamp > tp->rx_opt.rcv_tsecr)
diff --git a/net/ipv4/tcp_vegas.c b/net/ipv4/tcp_vegas.c
index 73e19cf7df21..e218a51ceced 100644
--- a/net/ipv4/tcp_vegas.c
+++ b/net/ipv4/tcp_vegas.c
@@ -117,6 +117,9 @@ void tcp_vegas_pkts_acked(struct sock *sk, u32 cnt, ktime_t last)
 	struct vegas *vegas = inet_csk_ca(sk);
 	u32 vrtt;
 
+	if (ktime_equal(last, net_invalid_timestamp()))
+		return;
+
 	/* Never allow zero rtt or baseRTT */
 	vrtt = ktime_to_us(net_timedelta(last)) + 1;
 
diff --git a/net/ipv4/tcp_veno.c b/net/ipv4/tcp_veno.c
index 9edb340f2f95..ec854cc5fad5 100644
--- a/net/ipv4/tcp_veno.c
+++ b/net/ipv4/tcp_veno.c
@@ -74,6 +74,9 @@ static void tcp_veno_pkts_acked(struct sock *sk, u32 cnt, ktime_t last)
 	struct veno *veno = inet_csk_ca(sk);
 	u32 vrtt;
 
+	if (ktime_equal(last, net_invalid_timestamp()))
+		return;
+
 	/* Never allow zero rtt or baseRTT */
 	vrtt = ktime_to_us(net_timedelta(last)) + 1;