tcp: fix tcp_grow_window() for large incoming frames

BugLink: http://bugs.launchpad.net/bugs/990544

[ Upstream commit 4d846f02392a710f9604892ac3329e628e60a230 ]

tcp_grow_window() has to grow rcv_ssthresh up to window_clamp, allowing
sender to increase its window.

tcp_grow_window() still assumes a tcp frame is under MSS, but its no
longer true with LRO/GRO.

This patch fixes one of the performance issue we noticed with GRO on.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Neal Cardwell <ncardwell@google.com>
Cc: Tom Herbert <therbert@google.com>
Acked-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 104b02e3ee2..c3a9f033ef3 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -328,6 +328,7 @@ static void tcp_grow_window(struct sock *sk, struct sk_buff *skb)
                         incr = __tcp_grow_window(sk, skb);
 
                 if (incr) {
+                        incr = max_t(int, incr, 2 * skb->len);
                         tp->rcv_ssthresh = min(tp->rcv_ssthresh + incr,
                                                tp->window_clamp);
                         inet_csk(sk)->icsk_ack.quick |= 1;