From d551e4541dd60ae53459f77a971f2d6043431f5f Mon Sep 17 00:00:00 2001 From: Ilpo Järvinen Date: Mon, 30 Apr 2007 00:42:20 -0700 Subject: [TCP] FRTO: RFC4138 allows Nagle override when new data must be sent MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit This is a corner case where less than MSS sized new data thingie is awaiting in the send queue. For F-RTO to work correctly, a new data segment must be sent at certain point or F-RTO cannot be used at all. RFC4138 allows overriding of Nagle at that point. Implementation uses frto_counter states 2 and 3 to distinguish when Nagle override is needed. Signed-off-by: Ilpo Järvinen Signed-off-by: David S. Miller --- net/ipv4/tcp_output.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) (limited to 'net/ipv4/tcp_output.c') diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c index b5fa3c19afee..0faacf9c419d 100644 --- a/net/ipv4/tcp_output.c +++ b/net/ipv4/tcp_output.c @@ -1035,8 +1035,10 @@ static inline int tcp_nagle_test(struct tcp_sock *tp, struct sk_buff *skb, if (nonagle & TCP_NAGLE_PUSH) return 1; - /* Don't use the nagle rule for urgent data (or for the final FIN). */ - if (tp->urg_mode || + /* Don't use the nagle rule for urgent data (or for the final FIN). + * Nagle can be ignored during F-RTO too (see RFC4138). + */ + if (tp->urg_mode || (tp->frto_counter == 2) || (TCP_SKB_CB(skb)->flags & TCPCB_FLAG_FIN)) return 1; -- cgit v1.2.3