Commit 2909d874 authored Oct 24, 2013 by Yuchung Cheng Committed by David S. Miller Oct 27, 2013

tcp: only take RTT from timestamps if new data is acked



Patch ed08495c "tcp: use RTT from SACK for RTO" has a bug that
it does not check if the ACK acknowledge new data before taking
the RTT sample from TCP timestamps. This patch adds the check
back as required by the RFC.

Signed-off-by: Yuchung Cheng <ycheng@google.com>
Acked-by: Neal Cardwell <ncardwell@google.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent bc15afa3

net/ipv4/tcp_input.c

+2 −1

Original line number	Diff line number	Diff line
		@@ -2856,7 +2856,8 @@ static inline bool tcp_ack_update_rtt(struct sock *sk, const int flag,
		* left edge of the send window.
		* See draft-ietf-tcplw-high-performance-00, section 3.3.
		*/
		if (seq_rtt < 0 && tp->rx_opt.saw_tstamp && tp->rx_opt.rcv_tsecr)
		if (seq_rtt < 0 && tp->rx_opt.saw_tstamp && tp->rx_opt.rcv_tsecr &&
		flag & FLAG_ACKED)
		seq_rtt = tcp_time_stamp - tp->rx_opt.rcv_tsecr;

		if (seq_rtt < 0)

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