On Wed, 2018-03-07 at 14:59 +0200, Ilpo Järvinen wrote:
> No functional changes.
>
> Signed-off-by: Ilpo Järvinen <ilpo.jarvi...@helsinki.fi>
> ---
> net/ipv4/tcp_input.c | 21 +++++++++++++++++----
> 1 file changed, 17 insertions(+), 4 deletions(-)
>
> diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
> index 1a33752..e20f9ad 100644
> --- a/net/ipv4/tcp_input.c
> +++ b/net/ipv4/tcp_input.c
> @@ -2211,6 +2211,19 @@ static void tcp_update_scoreboard(struct sock
> *sk, int fast_rexmit)
> }
> }
>
> +/* False fast retransmits may occur when SACK is not in use under
> certain
> + * conditions (RFC6582). The sender MUST hold old state until
> something
> + * *above* high_seq is ACKed to prevent triggering such false fast
> + * retransmits. SACK TCP is safe.
> + */
> +static bool tcp_false_fast_retrans_possible(const struct sock *sk,
> + const u32 snd_una)
> +{
> + const struct tcp_sock *tp = tcp_sk(sk);
> +
> + return ((snd_una == tp->high_seq) && tcp_is_reno(tp));
return (EXPR);
should use instead :
return EXPR;
> +}
> +
> static bool tcp_tsopt_ecr_before(const struct tcp_sock *tp, u32
> when)
> {
> return tp->rx_opt.saw_tstamp && tp->rx_opt.rcv_tsecr &&
> @@ -2350,10 +2363,10 @@ static bool tcp_try_undo_recovery(struct sock
> *sk)
> } else if (tp->rack.reo_wnd_persist) {
> tp->rack.reo_wnd_persist--;
> }
> - if (tp->snd_una == tp->high_seq && tcp_is_reno(tp)) {
> - /* Hold old state until something *above* high_seq
> - * is ACKed. For Reno it is MUST to prevent false
> - * fast retransmits (RFC2582). SACK TCP is safe. */
> + if (tcp_false_fast_retrans_possible(sk, tp->snd_una)) {
> + /* Hold old state until something *above* high_seq
> is ACKed
> + * if false fast retransmit is possible.
> + */
> if (!tcp_any_retrans_done(sk))
> tp->retrans_stamp = 0;
> return true;
