[TCP] Westwood: fix first sample

Need to update send sequence number tracking after first ack.
Rework of patch from Luca De Cicco.

Signed-off-by: Stephen Hemminger <shemminger@dxpl.pdx.osdl.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/ipv4/tcp_westwood.c b/net/ipv4/tcp_westwood.c
index 29eb258b6d8235b204384fa45cca81cbaac159e3..62a96b71b0dd733fb5587729456180d27986d7d6 100644 (file)
--- a/net/ipv4/tcp_westwood.c
+++ b/net/ipv4/tcp_westwood.c
@@ -22,6 +22,7 @@ struct westwood {
        u32    accounted;
        u32    rtt;
        u32    rtt_min;          /* minimum observed RTT */
+       u8     first_ack;        /* flag which infers that this is the first ack */
 };
 
 
@@ -52,6 +53,7 @@ static void tcp_westwood_init(struct sock *sk)
        w->rtt_min = w->rtt = TCP_WESTWOOD_INIT_RTT;
        w->rtt_win_sx = tcp_time_stamp;
        w->snd_una = tcp_sk(sk)->snd_una;
+       w->first_ack = 1;
 }
 
 /*
@@ -91,6 +93,15 @@ static void westwood_update_window(struct sock *sk)
        struct westwood *w = inet_csk_ca(sk);
        s32 delta = tcp_time_stamp - w->rtt_win_sx;
 
+       /* Initialise w->snd_una with the first acked sequence number in order
+        * to fix mismatch between tp->snd_una and w->snd_una for the first
+        * bandwidth sample
+        */
+        if (w->first_ack) {
+               w->snd_una = tcp_sk(sk)->snd_una;
+               w->first_ack = 0;
+       }
+
        /*
         * See if a RTT-window has passed.
         * Be careful since if RTT is less than
@@ -180,7 +191,7 @@ static void tcp_westwood_event(struct sock *sk, enum tcp_ca_event event)
 {
        struct tcp_sock *tp = tcp_sk(sk);
        struct westwood *w = inet_csk_ca(sk);
-
+       
        switch(event) {
        case CA_EVENT_FAST_ACK:
                westwood_fast_bw(sk);