tcp: Limit cwnd growth when deferring for GSO

This fixes inappropriately large cwnd growth on sender-limited flows
when GSO is enabled, limiting cwnd growth to 64k.

Signed-off-by: John Heffner <johnwheffner@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 2 insertions, 1 deletions

diff --git a/net/ipv4/tcp_cong.c b/net/ipv4/tcp_cong.c
index bfb1996bd99f..6a250828b767 100644
--- a/net/ipv4/tcp_cong.c
+++ b/net/ipv4/tcp_cong.c
@@ -287,7 +287,8 @@ int tcp_is_cwnd_limited(const struct sock *sk, u32 in_flight)
 
         left = tp->snd_cwnd - in_flight;
         if (sk_can_gso(sk) &&
-            left * sysctl_tcp_tso_win_divisor < tp->snd_cwnd)
+            left * sysctl_tcp_tso_win_divisor < tp->snd_cwnd &&
+            left * tp->mss_cache < sk->sk_gso_max_size)
                 return 1;
         return left <= tcp_max_burst(tp);
 }