[TCP]: Access to highest_sack obsoletes forward_cnt_hint

In addition, added a reference about the purpose of the loop.

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

2 files changed, 9 insertions, 15 deletions

diff --git a/include/linux/tcp.h b/include/linux/tcp.h
index c072f88afb97..d64734389fb6 100644
--- a/include/linux/tcp.h
+++ b/include/linux/tcp.h
@@ -346,7 +346,6 @@ struct tcp_sock {
         int     fastpath_cnt_hint;
         int     lost_cnt_hint;
         int     retransmit_cnt_hint;
-        int     forward_cnt_hint;
 
         u16     advmss;         /* Advertised MSS                       */
         u16     prior_ssthresh; /* ssthresh saved at recovery start     */
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 666d8a58d14a..b11025e8a49e 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -1945,33 +1945,28 @@ void tcp_xmit_retransmit_queue(struct sock *sk)
          * and retransmission... Both ways have their merits...
          *
          * For now we do not retransmit anything, while we have some new
-         * segments to send.
+         * segments to send. In the other cases, follow rule 3 for
+         * NextSeg() specified in RFC3517.
          */
 
         if (tcp_may_send_now(sk))
                 return;
 
-        if (tp->forward_skb_hint) {
+        /* If nothing is SACKed, highest_sack in the loop won't be valid */
+        if (!tp->sacked_out)
+                return;
+
+        if (tp->forward_skb_hint)
                 skb = tp->forward_skb_hint;
-                packet_cnt = tp->forward_cnt_hint;
-        } else{
+        else
                 skb = tcp_write_queue_head(sk);
-                packet_cnt = 0;
-        }
 
         tcp_for_write_queue_from(skb, sk) {
                 if (skb == tcp_send_head(sk))
                         break;
-                tp->forward_cnt_hint = packet_cnt;
                 tp->forward_skb_hint = skb;
 
-                /* Similar to the retransmit loop above we
-                 * can pretend that the retransmitted SKB
-                 * we send out here will be composed of one
-                 * real MSS sized packet because tcp_retransmit_skb()
-                 * will fragment it if necessary.
-                 */
-                if (++packet_cnt > tp->fackets_out)
+                if (after(TCP_SKB_CB(skb)->seq, tp->highest_sack))
                         break;
 
                 if (tcp_packets_in_flight(tp) >= tp->snd_cwnd)