[TCP]: Seperate DSACK from SACK fast path

[safe/jmp/linux-2.6] / net / ipv4 / tcp_input.c

diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 7670ef9..870f53a 100644 (file)
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -951,16 +951,43 @@ tcp_sacktag_write_queue(struct sock *sk, struct sk_buff *ack_skb, u32 prior_snd_
                tp->fackets_out = 0;
        prior_fackets = tp->fackets_out;
 
+       /* Check for D-SACK. */
+       if (before(ntohl(sp[0].start_seq), TCP_SKB_CB(ack_skb)->ack_seq)) {
+               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;
+               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 &&
+                       !after(ntohl(sp[0].end_seq), prior_snd_una) &&
+                       after(ntohl(sp[0].end_seq), tp->undo_marker))
+               tp->undo_retrans--;
+
+       /* Eliminate too old ACKs, but take into
+        * account more or less fresh ones, they can
+        * contain valid SACK info.
+        */
+       if (before(TCP_SKB_CB(ack_skb)->ack_seq, prior_snd_una - tp->max_window))
+               return 0;
+
        /* SACK fastpath:
         * if the only SACK change is the increase of the end_seq of
         * the first block then only apply that SACK block
         * and use retrans queue hinting otherwise slowpath */
        flag = 1;
-       for (i = 0; i< num_sacks; i++) {
-               __u32 start_seq = ntohl(sp[i].start_seq);
-               __u32 end_seq =  ntohl(sp[i].end_seq);
+       for (i = 0; i < num_sacks; i++) {
+               __be32 start_seq = sp[i].start_seq;
+               __be32 end_seq = sp[i].end_seq;
 
-               if (i == 0){
+               if (i == 0) {
                        if (tp->recv_sack_cache[i].start_seq != start_seq)
                                flag = 0;
                } else {
@@ -970,37 +997,6 @@ tcp_sacktag_write_queue(struct sock *sk, struct sk_buff *ack_skb, u32 prior_snd_
                }
                tp->recv_sack_cache[i].start_seq = start_seq;
                tp->recv_sack_cache[i].end_seq = end_seq;
-
-               /* Check for D-SACK. */
-               if (i == 0) {
-                       u32 ack = TCP_SKB_CB(ack_skb)->ack_seq;
-
-                       if (before(start_seq, ack)) {
-                               dup_sack = 1;
-                               tp->rx_opt.sack_ok |= 4;
-                               NET_INC_STATS_BH(LINUX_MIB_TCPDSACKRECV);
-                       } else if (num_sacks > 1 &&
-                                  !after(end_seq, ntohl(sp[1].end_seq)) &&
-                                  !before(start_seq, ntohl(sp[1].start_seq))) {
-                               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 &&
-                           !after(end_seq, prior_snd_una) &&
-                           after(end_seq, tp->undo_marker))
-                               tp->undo_retrans--;
-
-                       /* Eliminate too old ACKs, but take into
-                        * account more or less fresh ones, they can
-                        * contain valid SACK info.
-                        */
-                       if (before(ack, prior_snd_una - tp->max_window))
-                               return 0;
-               }
        }
 
        first_sack_index = 0;