Merge branch 'tcp-cong-undo_cwnd-mandatory'

Florian Westphal says:

====================
tcp: make undo_cwnd mandatory for congestion modules

highspeed, illinois, scalable, veno and yeah congestion control algorithms
don't provide a 'cwnd_undo' function.  This makes the stack default to a
'reno undo' which doubles cwnd.  However, the ssthresh implementation of
these algorithms do not halve the slowstart threshold. This causes similar
issue as the one fixed for dctcp in ce6dd23329b1e ("dctcp: avoid bogus
doubling of cwnd after loss").

In light of this it seems better to remove the fallback and make undo_cwnd
mandatory.

First patch fixes those spots where reno undo seems incorrect by providing
.cwnd_undo functions, second patch removes the fallback.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 1 insertions, 0 deletions

diff --git a/include/net/tcp.h b/include/net/tcp.h
index 123979fe12bf..7de80739adab 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -958,6 +958,7 @@ u32 tcp_slow_start(struct tcp_sock *tp, u32 acked);
 void tcp_cong_avoid_ai(struct tcp_sock *tp, u32 w, u32 acked);
 
 u32 tcp_reno_ssthresh(struct sock *sk);
+u32 tcp_reno_undo_cwnd(struct sock *sk);
 void tcp_reno_cong_avoid(struct sock *sk, u32 ack, u32 acked);
 extern struct tcp_congestion_ops tcp_reno;