On Thu, 21 Aug 2025, Chia-Yu Chang (Nokia) wrote:
> > -----Original Message-----
> > From: Eric Dumazet <eduma...@google.com>
> > Sent: Thursday, August 21, 2025 2:30 PM
> > To: Chia-Yu Chang (Nokia) <chia-yu.ch...@nokia-bell-labs.com>
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> > Subject: Re: [PATCH v15 net-next 10/14] tcp: accecn: AccECN option
> >
> >
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> >
> > On Fri, Aug 15, 2025 at 1:40 AM <chia-yu.ch...@nokia-bell-labs.com> wrote:
> [...]
> > > /* Used for make_synack to form the ACE flags */ diff --git
> > > a/include/uapi/linux/tcp.h b/include/uapi/linux/tcp.h index
> > > bdac8c42fa82..53e0e85b52be 100644
> > > --- a/include/uapi/linux/tcp.h
> > > +++ b/include/uapi/linux/tcp.h
> > > @@ -316,6 +316,13 @@ struct tcp_info {
> > > * in milliseconds, including any
> > > * unfinished recovery.
> > > */
> > > + __u32 tcpi_received_ce; /* # of CE marks received */
> > > + __u32 tcpi_delivered_e1_bytes; /* Accurate ECN byte counters */
> > > + __u32 tcpi_delivered_e0_bytes;
> > > + __u32 tcpi_delivered_ce_bytes;
> > > + __u32 tcpi_received_e1_bytes;
> > > + __u32 tcpi_received_e0_bytes;
> > > + __u32 tcpi_received_ce_bytes;
> > > };
> > >
> >
> > We do not add more fields to tcp_info, unless added fields are a multiple
> > of 64 bits.
> >
> > Otherwise a hole is added and can not be recovered.
>
> Hi Eric,
>
> Thanks for the feedback.
>
> Then, would it make sense to add __u32 reserved; here or this is not an
> option?
Wouldn't it also make sense to change the byte counters to __u64?
(It won't help the alignment though if the CE counter is left __u32.)
--
i.
