[TCP]: Add F-RTO support.

Motivation for this modification is that especially on some wireless
network technologies there are delay spikes that trigger RTO even though
no packets are lost. F-RTO sender continues by sending new data after RTO
retransmission in order to avoid unnecessary retransmissions in that case.  
If the sender sees any duplicate acks after the RTO retransmission, it
reverts to traditional slow start retransmissions. If new acks arrive
after forward transmissions, they very likely indicate that the RTO was
indeed spurious and the sender can continue sending new data (because 
only one segment was retransmitted).

1 files changed, 3 insertions, 0 deletions

diff --git a/include/linux/tcp.h b/include/linux/tcp.h
index ce34341d6a2c..91b66d7ab004 100644
--- a/include/linux/tcp.h
+++ b/include/linux/tcp.h
@@ -366,6 +366,9 @@ struct tcp_opt {
 	unsigned int		keepalive_intvl;  /* time interval between keep alive probes */
 	int			linger2;
 
+	int                     frto_counter; /* Number of new acks after RTO */
+	__u32                   frto_highmark; /* snd_nxt when RTO occurred */
+
 	unsigned long last_synq_overflow; 
 };