From a02d036c027e9070ca27c156f59eb445d5405480 Mon Sep 17 00:00:00 2001 From: Marcelo Ricardo Leitner Date: Fri, 23 Jun 2017 19:59:36 -0300 Subject: [PATCH] sctp: adjust ssthresh when transport is idle RFC 4960 Errata 3.27 identifies that ssthresh should be adjusted to cwnd because otherwise it could cause the transport to lock into congestion avoidance phase specially if ssthresh was previously reduced by some packet drop, leading to poor performance. The Errata says to adjust ssthresh to cwnd only once, though the same goal is achieved by updating it every time we update cwnd too. The caveat is that we could take longer to get back up to speed but that should be compensated by the fact that we don't adjust on RTO basis (as RFC says) but based on Heartbeats, which are usually way longer. See-also: https://tools.ietf.org/html/draft-ietf-tsvwg-rfc4960-errata-01#section-3.27 Signed-off-by: Marcelo Ricardo Leitner Signed-off-by: David S. Miller --- net/sctp/transport.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/net/sctp/transport.c b/net/sctp/transport.c index e3ebf04ddbd0..7cdd6bcddbc5 100644 --- a/net/sctp/transport.c +++ b/net/sctp/transport.c @@ -569,6 +569,8 @@ void sctp_transport_lower_cwnd(struct sctp_transport *transport, */ transport->cwnd = max(transport->cwnd/2, 4*asoc->pathmtu); + /* RFC 4960 Errata 3.27.2: also adjust sshthresh */ + transport->ssthresh = transport->cwnd; break; } -- 2.20.1