From 95445fc3284e757832fde1642e4bb937e66133d4 Mon Sep 17 00:00:00 2001
From: kieranm <kieranm>
Date: Thu, 28 Jan 2010 13:14:42 +0000
Subject: [PATCH] Ensure ssthresh >= 2*MSS

---
 CHANGELOG      | 2 ++
 src/core/tcp.c | 4 ++--
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/CHANGELOG b/CHANGELOG
index 3a2b17d1..dbab0d7b 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -56,6 +56,8 @@ HISTORY
 
 
   ++ Bugfixes:
+  2010-01-28: Kieran Mansley
+  * tcp.c: Ensure ssthresh >= 2*MSS
 
   2010-01-27: Simon Goldschmidt
   * tcp.h, tcp.c, tcp_in.c: Fixed bug #27871: Calling tcp_abort() in recv
diff --git a/src/core/tcp.c b/src/core/tcp.c
index 1ac824db..2b328424 100644
--- a/src/core/tcp.c
+++ b/src/core/tcp.c
@@ -650,8 +650,8 @@ tcp_slowtmr(void)
           /* Reduce congestion window and ssthresh. */
           eff_wnd = LWIP_MIN(pcb->cwnd, pcb->snd_wnd);
           pcb->ssthresh = eff_wnd >> 1;
-          if (pcb->ssthresh < pcb->mss) {
-            pcb->ssthresh = pcb->mss * 2;
+          if (pcb->ssthresh < (pcb->mss << 1)) {
+            pcb->ssthresh = (pcb->mss << 1);
           }
           pcb->cwnd = pcb->mss;
           LWIP_DEBUGF(TCP_CWND_DEBUG, ("tcp_slowtmr: cwnd %"U16_F