netdev - Re: [PATCH v21 bpf-next 18/23] libbpf: Add SEC name for xdp

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Message-ID: <CAEf4BzZAMtmqW4sMfhEX8WtAzmQoVQ=WupqeqXa=5KbYXAbQNA@mail.gmail.com>
Date:   Fri, 14 Jan 2022 11:36:48 -0800
From:   Andrii Nakryiko <andrii.nakryiko@...il.com>
To:     Zvi Effron <zeffron@...tgames.com>
Cc:     Jesper Dangaard Brouer <jbrouer@...hat.com>,
        Alexei Starovoitov <alexei.starovoitov@...il.com>,
        Lorenzo Bianconi <lorenzo@...nel.org>,
        Jesper Dangaard Brouer <brouer@...hat.com>,
        Toke Høiland-Jørgensen <toke@...hat.com>,
        Lorenzo Bianconi <lorenzo.bianconi@...hat.com>,
        bpf <bpf@...r.kernel.org>, Networking <netdev@...r.kernel.org>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Shay Agroskin <shayagr@...zon.com>,
        john fastabend <john.fastabend@...il.com>,
        David Ahern <dsahern@...nel.org>,
        Eelco Chaudron <echaudro@...hat.com>,
        Jason Wang <jasowang@...hat.com>,
        Alexander Duyck <alexander.duyck@...il.com>,
        Saeed Mahameed <saeed@...nel.org>,
        Maciej Fijalkowski <maciej.fijalkowski@...el.com>,
        Magnus Karlsson <magnus.karlsson@...el.com>,
        tirthendu.sarkar@...el.com
Subject: Re: [PATCH v21 bpf-next 18/23] libbpf: Add SEC name for xdp_mb programs

On Fri, Jan 14, 2022 at 10:55 AM Zvi Effron <zeffron@...tgames.com> wrote:
>
> On Fri, Jan 14, 2022 at 8:50 AM Jesper Dangaard Brouer
> <jbrouer@...hat.com> wrote:
> >
> >
> >
> > On 14/01/2022 03.09, Alexei Starovoitov wrote:
> > > On Thu, Jan 13, 2022 at 3:58 PM Lorenzo Bianconi <lorenzo@...nel.org> wrote:
> > >>>
> > >>> Btw "xdp_cpumap" should be cleaned up.
> > >>> xdp_cpumap is an attach type. It's not prog type.
> > >>> Probably it should be "xdp/cpumap" to align with "cgroup/bind[46]" ?
> > >>
> > >> so for xdp "mb" or xdp "frags" it will be xdp/cpumap.mb (xdp/devmap.mb) or
> > >> xdp/cpumap.frags (xdp/devmap.frags), right?
> > >
> > > xdp.frags/cpumap
> > > xdp.frags/devmap
> > >
> > > The current de-facto standard for SEC("") in libbpf:
> > > prog_type.prog_flags/attach_place
> >
> > Ups, did we make a mistake with SEC("xdp_devmap/")
> >
> > and can we correct without breaking existing programs?
> >
>
> We can (at the very least) add the correct sections, even if we leave the
> current incorrect ones as well. Ideally we'd mark the incorrect ones deprecated
> and either remove them before libbpf 1.0 or as part of 2.0?
>

Correct, those would need to be new aliases. We can also deprecate old
ones, if we have consensus on that. We can teach libbpf to emit
warnings (through logs, of course) for such uses of to-be-removed
sections aliases. We still have probably a few months before the final
1.0 release, should hopefully be plenty of time to people to adapt.

> --Zvi
>
> > > "attach_place" is either function_name for fentry/, tp/, lsm/, etc.
> > > or attach_type/hook/target for cgroup/bind4, cgroup_skb/egress.
> > >
> > > lsm.s/socket_bind -> prog_type = LSM, flags = SLEEPABLE
> > > lsm/socket_bind -> prog_type = LSM, non sleepable.
> > >
> >