Date: Wed, 31 Oct 2018 10:04:44 -0400 From: Jacques Fourie <jacques.fourie@gmail.com> To: Hackers freeBSD <freebsd-hackers@freebsd.org> Subject: TCP RTT estimate for connections not using timestamps Message-ID: <CALX0vxCLYdrVyVTdwdh_K1RjYp6VW-0uBvFk5arRiZ5xMKV9QQ@mail.gmail.com>
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Hi, While testing with traffic generators that don=E2=80=99t enable the TCP tim= estamp option I noticed a couple of cases where tcp_xmit_timer() was called with a 0 value for rtt with the current smoothed rtt (t_srtt) non zero. This leads to a left shift of -1 which is undefined. Looking at the code for the case where timestamps are enabled I see that tcp_xmit_timer() is always called with TCP_TS_TO_TICKS(t) + 1 for the rtt. Do we need a +1 in the non timestamp case as well? Thanks, Jacques
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