[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, 3 insertions, 3 deletions

diff --git a/net/ipv4/tcp_cong.c b/net/ipv4/tcp_cong.c
index 91c2f41c7f58..857eefc52aab 100644
--- a/net/ipv4/tcp_cong.c
+++ b/net/ipv4/tcp_cong.c
@@ -38,7 +38,7 @@ int tcp_register_congestion_control(struct tcp_congestion_ops *ca)
         int ret = 0;
 
         /* all algorithms must implement ssthresh and cong_avoid ops */
-        if (!ca->ssthresh || !ca->cong_avoid || !ca->min_cwnd) {
+        if (!ca->ssthresh || !ca->cong_avoid) {
                 printk(KERN_ERR "TCP %s does not implement required ops\n",
                        ca->name);
                 return -EINVAL;
@@ -251,8 +251,8 @@ u32 tcp_reno_ssthresh(struct sock *sk)
 }
 EXPORT_SYMBOL_GPL(tcp_reno_ssthresh);
 
-/* Lower bound on congestion window. */
-u32 tcp_reno_min_cwnd(struct sock *sk)
+/* Lower bound on congestion window with halving. */
+u32 tcp_reno_min_cwnd(const struct sock *sk)
 {
         const struct tcp_sock *tp = tcp_sk(sk);
         return tp->snd_ssthresh/2;