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>

diff --git a/net/ipv4/tcp_cong.c b/net/ipv4/tcp_cong.c
index bfb1996bd99ff420af679d181017834f24d7b888..6a250828b767aef7f037a3cf10d10b1dd74625cb 100644 (file)
--- 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);
 }