netdev - Re: [PATCH bpf-next 1/2] net: xdp: refactor XDP_QUERY_PROG{,

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Message-ID: <CAJ+HfNhB3zs7uG+N0QyKC1PE4ZhA+dpo-kJeJYbh_mwQNPnKKg@mail.gmail.com>
Date:   Wed, 22 May 2019 23:12:28 +0200
From:   Björn Töpel <bjorn.topel@...il.com>
To:     Jakub Kicinski <jakub.kicinski@...ronome.com>
Cc:     Toke Høiland-Jørgensen <toke@...hat.com>,
        Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Netdev <netdev@...r.kernel.org>,
        Björn Töpel <bjorn.topel@...el.com>,
        "Karlsson, Magnus" <magnus.karlsson@...el.com>,
        Jesper Dangaard Brouer <brouer@...hat.com>,
        bpf <bpf@...r.kernel.org>
Subject: Re: [PATCH bpf-next 1/2] net: xdp: refactor XDP_QUERY_PROG{,_HW} to netdev

On Wed, 22 May 2019 at 23:04, Jakub Kicinski
<jakub.kicinski@...ronome.com> wrote:
>
> On Wed, 22 May 2019 22:54:44 +0200, Björn Töpel wrote:
> > > > Now, the same commands give:
> > > >
> > > >   # ip link set dev eth0 xdp obj foo.o sec main
> > > >   # ip link set dev eth0 xdpgeneric off
> > > >   Error: native and generic XDP can't be active at the same time.
> > >
> > > I'm not clear why this change is necessary? It is a change in
> > > behaviour, and if anything returning ENOENT would seem cleaner
> > > in this case.
> >
> > To me, the existing behavior was non-intuitive. If most people *don't*
> > agree, I'll remove this change. So, what do people think about this?
> > :-)
>
> Having things start to fail after they were successful/ignored
> is one of those ABI breakage types Linux and netdev usually takes
> pretty seriously, unfortunately.  Especially when motivation is
> "it's more intuitive" :)
>

Hey, intuition is a great thing! :-D

> If nobody chimes in please break out this behaviour change into
> a commit of its own.
>

Will do.


Björn


> > ENOENT does make more sense.