On Mon, 01 May 2017 15:29:48 -0700
Eric Dumazet <eric.duma...@gmail.com> wrote:
> From: Eric Dumazet <eduma...@google.com>
>
> Be careful when comparing tcp_time_stamp to some u32 quantity,
> otherwise result can be surprising.
>
> Fixes: 7c106d7e782b ("[TCP]: TCP Low Priority congestion control")
> Signed-off-by: Eric Dumazet <eduma...@google.com>
> ---
> net/ipv4/tcp_lp.c | 6 ++++--
> 1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/net/ipv4/tcp_lp.c b/net/ipv4/tcp_lp.c
> index
> 046fd3910873306d74207615d6997e1c847ea361..d6fb6c067af4641f232b94e7c590c212648e8173
> 100644
> --- a/net/ipv4/tcp_lp.c
> +++ b/net/ipv4/tcp_lp.c
> @@ -264,13 +264,15 @@ static void tcp_lp_pkts_acked(struct sock *sk, const
> struct ack_sample *sample)
> {
> struct tcp_sock *tp = tcp_sk(sk);
> struct lp *lp = inet_csk_ca(sk);
> + u32 delta;
>
> if (sample->rtt_us > 0)
> tcp_lp_rtt_sample(sk, sample->rtt_us);
>
> /* calc inference */
> - if (tcp_time_stamp > tp->rx_opt.rcv_tsecr)
> - lp->inference = 3 * (tcp_time_stamp - tp->rx_opt.rcv_tsecr);
> + delta = tcp_time_stamp - tp->rx_opt.rcv_tsecr;
> + if ((s32)delta > 0)
> + lp->inference = 3 * delta;
Agreed time wraparound would cause problems.
But why not use existing time_after() macro here?
