[TCP]: Abstract tp->highest_sack accessing & point to next skb

Pointing to the next skb is necessary to avoid referencing
already SACKed skbs which will soon be on a separate list.

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 3 insertions, 8 deletions

diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 7d8583a15d02..9a985b55e7d8 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -667,7 +667,7 @@ static void tcp_adjust_fackets_out(struct sock *sk, struct sk_buff *skb,
         if (!tp->sacked_out || tcp_is_reno(tp))
                 return;
 
-        if (!before(tcp_highest_sack_seq(tp), TCP_SKB_CB(skb)->seq))
+        if (after(tcp_highest_sack_seq(tp), TCP_SKB_CB(skb)->seq))
                 tp->fackets_out -= decr;
 }
 
@@ -711,9 +711,6 @@ int tcp_fragment(struct sock *sk, struct sk_buff *skb, u32 len, unsigned int mss
         TCP_SKB_CB(buff)->end_seq = TCP_SKB_CB(skb)->end_seq;
         TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(buff)->seq;
 
-        if (tcp_is_sack(tp) && tp->sacked_out && (skb == tp->highest_sack))
-                tp->highest_sack = buff;
-
         /* PSH and FIN should only be set in the second packet. */
         flags = TCP_SKB_CB(skb)->flags;
         TCP_SKB_CB(skb)->flags = flags & ~(TCPCB_FLAG_FIN|TCPCB_FLAG_PSH);
@@ -1707,9 +1704,7 @@ 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);
 
-                if (WARN_ON(tcp_is_sack(tp) && tp->sacked_out &&
-                    (next_skb == tp->highest_sack)))
-                        return;
+                tcp_highest_sack_combine(sk, next_skb, skb);
 
                 /* Ok.  We will be able to collapse the packet. */
                 tcp_unlink_write_queue(next_skb, sk);
@@ -2019,7 +2014,7 @@ void tcp_xmit_retransmit_queue(struct sock *sk)
                         break;
                 tp->forward_skb_hint = skb;
 
-                if (after(TCP_SKB_CB(skb)->seq, tcp_highest_sack_seq(tp)))
+                if (!before(TCP_SKB_CB(skb)->seq, tcp_highest_sack_seq(tp)))
                         break;
 
                 if (tcp_packets_in_flight(tp) >= tp->snd_cwnd)