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Commit 2909d874 authored by Yuchung Cheng's avatar Yuchung Cheng Committed by David S. Miller
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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: default avatarYuchung Cheng <ycheng@google.com>
Acked-by: default avatarNeal Cardwell <ncardwell@google.com>
Acked-by: default avatarEric Dumazet <edumazet@google.com>
Signed-off-by: default avatarDavid 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)