[TCP]: Minimum congestion window consolidation.

Many of the TCP congestion methods all just use ssthresh
as the minimum congestion window on decrease.  Rather than
duplicating the code, just have that be the default if that
handle in the ops structure is not set.

Minor behaviour change to TCP compound.  It probably wants
to use this (ssthresh) as lower bound, rather than ssthresh/2
because the latter causes undershoot on loss.

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

1 files changed, 7 insertions, 11 deletions

diff --git a/net/ipv4/tcp_westwood.c b/net/ipv4/tcp_westwood.c
index 0c340c3756c2..29eb258b6d82 100644
--- a/net/ipv4/tcp_westwood.c
+++ b/net/ipv4/tcp_westwood.c
@@ -162,12 +162,6 @@ static inline u32 westwood_acked_count(struct sock *sk)
         return w->cumul_ack;
 }
 
-static inline u32 westwood_bw_rttmin(const struct sock *sk)
-{
-        const struct tcp_sock *tp = tcp_sk(sk);
-        const struct westwood *w = inet_csk_ca(sk);
-        return max_t(u32, (w->bw_est * w->rtt_min) / tp->mss_cache, 2);
-}
 
 /*
  * TCP Westwood
@@ -175,9 +169,11 @@ static inline u32 westwood_bw_rttmin(const struct sock *sk)
  * in packets we use mss_cache). Rttmin is guaranteed to be >= 2
  * so avoids ever returning 0.
  */
-static u32 tcp_westwood_cwnd_min(struct sock *sk)
+static u32 tcp_westwood_bw_rttmin(const struct sock *sk)
 {
-        return westwood_bw_rttmin(sk);
+        const struct tcp_sock *tp = tcp_sk(sk);
+        const struct westwood *w = inet_csk_ca(sk);
+        return max_t(u32, (w->bw_est * w->rtt_min) / tp->mss_cache, 2);
 }
 
 static void tcp_westwood_event(struct sock *sk, enum tcp_ca_event event)
@@ -191,11 +187,11 @@ static void tcp_westwood_event(struct sock *sk, enum tcp_ca_event event)
                 break;
 
         case CA_EVENT_COMPLETE_CWR:
-                tp->snd_cwnd = tp->snd_ssthresh = westwood_bw_rttmin(sk);
+                tp->snd_cwnd = tp->snd_ssthresh = tcp_westwood_bw_rttmin(sk);
                 break;
 
         case CA_EVENT_FRTO:
-                tp->snd_ssthresh = westwood_bw_rttmin(sk);
+                tp->snd_ssthresh = tcp_westwood_bw_rttmin(sk);
                 break;
 
         case CA_EVENT_SLOW_ACK:
@@ -235,7 +231,7 @@ static struct tcp_congestion_ops tcp_westwood = {
         .init           = tcp_westwood_init,
         .ssthresh       = tcp_reno_ssthresh,
         .cong_avoid     = tcp_reno_cong_avoid,
-        .min_cwnd       = tcp_westwood_cwnd_min,
+        .min_cwnd       = tcp_westwood_bw_rttmin,
         .cwnd_event     = tcp_westwood_event,
         .get_info       = tcp_westwood_info,
         .pkts_acked     = tcp_westwood_pkts_acked,