On Thu, Mar 10, 2016 at 9:29 AM, Martin KaFai Lau <ka...@fb.com> wrote: > Per RFC4898, they count segments sent/received > containing a positive length data segment (that includes > retransmission segments carrying data). Unlike > tcpi_segs_out/in, tcpi_data_segs_out/in excludes segments > carrying no data (e.g. pure ack). > > The patch also updates the segs_in in tcp_fastopen_add_skb() > so that segs_in >= data_segs_in property is kept. If > tcp_segs_in() helper is used in this fastopen case, tp->segs_in > has to be 0 reset first to avoid double counting. Also, it has > to be done before __skb_pull(skb, tcp_hdrlen(skb)) while > there is no need to check skb->len since skb has already > been confirmed carrying data. I found it more confusing > and chose to directly set segs_in and data_segs_in in > this special case.
Note that on my TODO list after commit e11ecddf5128011c936cc5360780190cbc901fdc I had the project of pulling TCP headers much earlier in input path so that we do not have all these special cases. Acked-by: Eric Dumazet <eduma...@google.com>
