3 files changed, 21 insertions, 11 deletions

diff --git a/include/net/tcp.h b/include/net/tcp.h
index d78ad9bfcfa..456983d1fce 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -1067,11 +1067,15 @@ static inline void tcp_mib_init(void)
 }
 
 /* from STCP */
-static inline void tcp_clear_all_retrans_hints(struct tcp_sock *tp) {
+static inline void tcp_clear_retrans_hints_partial(struct tcp_sock *tp) {
 	tp->lost_skb_hint = NULL;
 	tp->scoreboard_skb_hint = NULL;
 	tp->retransmit_skb_hint = NULL;
 	tp->forward_skb_hint = NULL;
+}
+
+static inline void tcp_clear_all_retrans_hints(struct tcp_sock *tp) {
+	tcp_clear_retrans_hints_partial(tp);
 	tp->fastpath_skb_hint = NULL;
 }
 
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 65b9f274a77..4c10d9cad20 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -1671,7 +1671,7 @@ static void tcp_enter_frto_loss(struct sock *sk, int allowed_segments, int flag)
 	tp->high_seq = tp->frto_highmark;
 	TCP_ECN_queue_cwr(tp);
 
-	tcp_clear_all_retrans_hints(tp);
+	tcp_clear_retrans_hints_partial(tp);
 }
 
 void tcp_clear_retrans(struct tcp_sock *tp)
@@ -1711,10 +1711,14 @@ void tcp_enter_loss(struct sock *sk, int how)
 	tp->bytes_acked = 0;
 	tcp_clear_retrans(tp);
 
-	/* Push undo marker, if it was plain RTO and nothing
-	 * was retransmitted. */
-	if (!how)
+	if (!how) {
+		/* Push undo marker, if it was plain RTO and nothing
+		 * was retransmitted. */
 		tp->undo_marker = tp->snd_una;
+		tcp_clear_retrans_hints_partial(tp);
+	} else {
+		tcp_clear_all_retrans_hints(tp);
+	}
 
 	tcp_for_write_queue(skb, sk) {
 		if (skb == tcp_send_head(sk))
@@ -1741,8 +1745,6 @@ void tcp_enter_loss(struct sock *sk, int how)
 	TCP_ECN_queue_cwr(tp);
 	/* Abort FRTO algorithm if one is in progress */
 	tp->frto_counter = 0;
-
-	tcp_clear_all_retrans_hints(tp);
 }
 
 static int tcp_check_sack_reneging(struct sock *sk)
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index f46d24b8410..cbb83acd830 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -687,7 +687,7 @@ int tcp_fragment(struct sock *sk, struct sk_buff *skb, u32 len, unsigned int mss
 
 	BUG_ON(len > skb->len);
 
-	tcp_clear_all_retrans_hints(tp);
+	tcp_clear_retrans_hints_partial(tp);
 	nsize = skb_headlen(skb) - len;
 	if (nsize < 0)
 		nsize = 0;
@@ -1718,9 +1718,6 @@ static void tcp_retrans_try_collapse(struct sock *sk, struct sk_buff *skb, int m
 		BUG_ON(tcp_skb_pcount(skb) != 1 ||
 		       tcp_skb_pcount(next_skb) != 1);
 
-		/* changing transmit queue under us so clear hints */
-		tcp_clear_all_retrans_hints(tp);
-
 		/* Ok.	We will be able to collapse the packet. */
 		tcp_unlink_write_queue(next_skb, sk);
 
@@ -1759,6 +1756,13 @@ static void tcp_retrans_try_collapse(struct sock *sk, struct sk_buff *skb, int m
 
 		tcp_adjust_fackets_out(tp, skb, tcp_skb_pcount(next_skb));
 		tp->packets_out -= tcp_skb_pcount(next_skb);
+
+		/* changed transmit queue under us so clear hints */
+		tcp_clear_retrans_hints_partial(tp);
+		/* manually tune sacktag skb hint */
+		if (tp->fastpath_skb_hint == next_skb)
+			tp->fastpath_skb_hint = skb;
+
 		sk_stream_free_skb(sk, next_skb);
 	}
 }