From 016818d076871c4ee34db1e8d74dc17ac1de626a Mon Sep 17 00:00:00 2001 From: Neal Cardwell Date: Sat, 22 Sep 2012 04:18:55 +0000 Subject: [PATCH] tcp: TCP Fast Open Server - take SYNACK RTT after completing 3WHS When taking SYNACK RTT samples for servers using TCP Fast Open, fix the code to ensure that we only call tcp_valid_rtt_meas() after we receive the ACK that completes the 3-way handshake. Previously we were always taking an RTT sample in tcp_v4_syn_recv_sock(). However, for TCP Fast Open connections tcp_v4_conn_req_fastopen() calls tcp_v4_syn_recv_sock() at the time we receive the SYN. So for TFO we must wait until tcp_rcv_state_process() to take the RTT sample. To fix this, we wait until after TFO calls tcp_v4_syn_recv_sock() before we set the snt_synack timestamp, since tcp_synack_rtt_meas() already ensures that we only take a SYNACK RTT sample if snt_synack is non-zero. To be careful, we only take a snt_synack timestamp when a SYNACK transmit or retransmit succeeds. Signed-off-by: Neal Cardwell Signed-off-by: David S. Miller --- include/net/tcp.h | 1 + net/ipv4/tcp_input.c | 1 + net/ipv4/tcp_ipv4.c | 12 +++++++++--- net/ipv6/tcp_ipv6.c | 2 +- 4 files changed, 12 insertions(+), 4 deletions(-) diff --git a/include/net/tcp.h b/include/net/tcp.h index a718d0e3d8e7..6feeccd83dd7 100644 --- a/include/net/tcp.h +++ b/include/net/tcp.h @@ -1125,6 +1125,7 @@ static inline void tcp_openreq_init(struct request_sock *req, req->cookie_ts = 0; tcp_rsk(req)->rcv_isn = TCP_SKB_CB(skb)->seq; tcp_rsk(req)->rcv_nxt = TCP_SKB_CB(skb)->seq + 1; + tcp_rsk(req)->snt_synack = 0; req->mss = rx_opt->mss_clamp; req->ts_recent = rx_opt->saw_tstamp ? rx_opt->rcv_tsval : 0; ireq->tstamp_ok = rx_opt->tstamp_ok; diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index e2bec815ff23..bb326684495b 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -5983,6 +5983,7 @@ int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb, * need req so release it. */ if (req) { + tcp_synack_rtt_meas(sk, req); reqsk_fastopen_remove(sk, req, false); } else { /* Make sure socket is routed, for diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c index 1e66f7fb4fe6..0a7e020f16b5 100644 --- a/net/ipv4/tcp_ipv4.c +++ b/net/ipv4/tcp_ipv4.c @@ -868,6 +868,8 @@ static int tcp_v4_send_synack(struct sock *sk, struct dst_entry *dst, ireq->rmt_addr, ireq->opt); err = net_xmit_eval(err); + if (!tcp_rsk(req)->snt_synack && !err) + tcp_rsk(req)->snt_synack = tcp_time_stamp; } return err; @@ -1382,6 +1384,7 @@ static int tcp_v4_conn_req_fastopen(struct sock *sk, struct request_sock_queue *queue = &inet_csk(sk)->icsk_accept_queue; const struct inet_request_sock *ireq = inet_rsk(req); struct sock *child; + int err; req->retrans = 0; req->sk = NULL; @@ -1393,8 +1396,11 @@ static int tcp_v4_conn_req_fastopen(struct sock *sk, kfree_skb(skb_synack); return -1; } - ip_build_and_send_pkt(skb_synack, sk, ireq->loc_addr, - ireq->rmt_addr, ireq->opt); + err = ip_build_and_send_pkt(skb_synack, sk, ireq->loc_addr, + ireq->rmt_addr, ireq->opt); + err = net_xmit_eval(err); + if (!err) + tcp_rsk(req)->snt_synack = tcp_time_stamp; /* XXX (TFO) - is it ok to ignore error and continue? */ spin_lock(&queue->fastopenq->lock); @@ -1612,7 +1618,6 @@ int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb) isn = tcp_v4_init_sequence(skb); } tcp_rsk(req)->snt_isn = isn; - tcp_rsk(req)->snt_synack = tcp_time_stamp; if (dst == NULL) { dst = inet_csk_route_req(sk, &fl4, req); @@ -1650,6 +1655,7 @@ int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb) if (err || want_cookie) goto drop_and_free; + tcp_rsk(req)->snt_synack = tcp_time_stamp; tcp_rsk(req)->listener = NULL; /* Add the request_sock to the SYN table */ inet_csk_reqsk_queue_hash_add(sk, req, TCP_TIMEOUT_INIT); diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c index cfeeeb7fcf54..d6212d6bc8d8 100644 --- a/net/ipv6/tcp_ipv6.c +++ b/net/ipv6/tcp_ipv6.c @@ -1169,7 +1169,6 @@ static int tcp_v6_conn_request(struct sock *sk, struct sk_buff *skb) } have_isn: tcp_rsk(req)->snt_isn = isn; - tcp_rsk(req)->snt_synack = tcp_time_stamp; if (security_inet_conn_request(sk, skb, req)) goto drop_and_release; @@ -1180,6 +1179,7 @@ have_isn: want_cookie) goto drop_and_free; + tcp_rsk(req)->snt_synack = tcp_time_stamp; tcp_rsk(req)->listener = NULL; inet6_csk_reqsk_queue_hash_add(sk, req, TCP_TIMEOUT_INIT); return 0;