tcp: don't clear retransmit_skb_hint when not necessary

Most importantly avoid doing it with cumulative ACK. Not clearing
means that we no longer need n^2 processing in resolution of each
fast recovery.

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 3 insertions, 1 deletions

diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index d017aed6edd7..44a4fffc2cc3 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -2925,7 +2925,9 @@ static int tcp_clean_rtx_queue(struct sock *sk, int prior_fackets)
 
                 tcp_unlink_write_queue(skb, sk);
                 sk_wmem_free_skb(sk, skb);
-                tcp_clear_all_retrans_hints(tp);
+                tcp_clear_retrans_hints_partial(tp);
+                if (skb == tp->retransmit_skb_hint)
+                        tp->retransmit_skb_hint = NULL;
         }
 
         if (skb && (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_ACKED))