3.12-stable review patch. If anyone has any objections, please let me know. ------------------ From: Yuchung Cheng <ycheng@xxxxxxxxxx> [ Upstream commit 2909d874f34eae157aecab0af27c6dc4a1751f8f ] Patch ed08495c3 "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@xxxxxxxxxx> Acked-by: Neal Cardwell <ncardwell@xxxxxxxxxx> Acked-by: Eric Dumazet <edumazet@xxxxxxxxxx> Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- net/ipv4/tcp_input.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -2856,7 +2856,8 @@ static inline bool tcp_ack_update_rtt(st * 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) -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html