netdev - Re: [PATCH bpf-next 8/8] selftests/bpf: switch tests to BTF-defined map definitions

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Date:   Mon, 17 Jun 2019 12:30:37 -0700
From:   Andrii Nakryiko <andrii.nakryiko@...il.com>
To:     Stanislav Fomichev <sdf@...ichev.me>
Cc:     Andrii Nakryiko <andriin@...com>, bpf <bpf@...r.kernel.org>,
        Networking <netdev@...r.kernel.org>,
        Alexei Starovoitov <ast@...com>,
        Daniel Borkmann <daniel@...earbox.net>,
        Kernel Team <kernel-team@...com>
Subject: Re: [PATCH bpf-next 8/8] selftests/bpf: switch tests to BTF-defined
 map definitions

On Fri, Jun 14, 2019 at 5:01 PM Stanislav Fomichev <sdf@...ichev.me> wrote:
>
> On 06/14, Andrii Nakryiko wrote:
> > On Fri, Jun 14, 2019 at 4:23 PM Stanislav Fomichev <sdf@...ichev.me> wrote:
> > >
> > > On 06/10, Andrii Nakryiko wrote:
> > > > Switch test map definition to new BTF-defined format.
> > > Reiterating my concerns on non-RFC version:
> > >
> > > Pretty please, let's not convert everything at once. Let's start
> > > with stuff that explicitly depends on BTF (spinlocks?).
> >
> > How about this approach. I can split last commit into two. One
> > converting all the stuff that needs BTF (spinlocks, etc). Another part
> > - everything else. If it's so important for your use case, you'll be
> > able to just back out my last commit. Or we just don't land last
> > commit.
> I can always rollback or do not backport internally; the issue is that
> it would be much harder to backport any future fixes/extensions to
> those tests. So splitting in two and not landing the last one is
> preferable ;-)

So I just posted v2 and I split all the test conversions into three parts:
1. tests that already rely on BTF
2. tests w/ custom key/value types
3. all the reset

I think we should definitely apply #1. I think #2 would be nice. And
we can probably hold off on #3. I'll let Alexei or Daniel decide, but
it shouldn't be hard for them to do that.

>
> > > One good argument (aside from the one that we'd like to be able to
> > > run tests internally without BTF for a while): libbpf doesn't
> > > have any tests as far as I'm aware. If we don't have 'legacy' maps in the
> > > selftests, libbpf may bit rot.
> >
> > I left few legacy maps exactly for that reason. See progs/test_btf_*.c.
> Damn it, you've destroyed my only good argument.

Heh :)

>
> > > (Andrii, feel free to ignore, since we've already discussed that)
> > >
> > > > Signed-off-by: Andrii Nakryiko <andriin@...com>
> > > > ---
> >
> >
> > <snip>