Hello!
On 03/09/2018 05:10 PM, Ilpo Järvinen wrote:
> A miscalculation for the number of acknowledged packets occurs during
> RTO recovery whenever SACK is not enabled and a cumulative ACK covers
> any non-retransmitted skbs. The reason is that pkts_acked value
> calculated in tcp_clean_rtx_queue is not correct for slow start after
> RTO as it may include segments that were not lost and therefore did
> not need retransmissions in the slow start following the RTO. Then
> tcp_slow_start will add the excess into cwnd bloating it and
> triggering a burst.
>
> Instead, we want to pass only the number of retransmitted segments
> that were covered by the cumulative ACK (and potentially newly sent
> data segments too if the cumulative ACK covers that far).
>
> Signed-off-by: Ilpo Järvinen <ilpo.jarvi...@helsinki.fi>
> ---
> net/ipv4/tcp_input.c | 19 +++++++++++++++++--
> 1 file changed, 17 insertions(+), 2 deletions(-)
>
> diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
> index 9a1b3c1..0305f6d 100644
> --- a/net/ipv4/tcp_input.c
> +++ b/net/ipv4/tcp_input.c
[...]
> @@ -3068,8 +3072,11 @@ static int tcp_clean_rtx_queue(struct sock *sk, u32
> prior_fack,
> last_in_flight = TCP_SKB_CB(skb)->tx.in_flight;
> if (before(start_seq, reord))
> reord = start_seq;
> - if (!after(scb->end_seq, tp->high_seq))
> + if (!after(scb->end_seq, tp->high_seq)) {
> flag |= FLAG_ORIG_SACK_ACKED;
> + } else {
> + newdata_acked += acked_pcount;
> + }
Why add {} where they're not needed?
[...]
MBR, Sergei
