netdev - Re: [PATCH bpf-next 0/5] libbpf: error reporting changes for v1.0

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Message-ID: <87a6ojzwdi.fsf@toke.dk>
Date:   Mon, 24 May 2021 22:53:45 +0200
From:   Toke Høiland-Jørgensen <toke@...hat.com>
To:     Andrii Nakryiko <andrii.nakryiko@...il.com>,
        John Fastabend <john.fastabend@...il.com>,
        Stanislav Fomichev <sdf@...gle.com>
Cc:     Andrii Nakryiko <andrii@...nel.org>, 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 0/5] libbpf: error reporting changes for v1.0

Andrii Nakryiko <andrii.nakryiko@...il.com> writes:

> On Sun, May 23, 2021 at 11:36 PM John Fastabend
> <john.fastabend@...il.com> wrote:
>>
>> Andrii Nakryiko wrote:
>> > Implement error reporting changes discussed in "Libbpf: the road to v1.0"
>> > ([0]) document.
>> >
>> > Libbpf gets a new API, libbpf_set_strict_mode() which accepts a set of flags
>> > that turn on a set of libbpf 1.0 changes, that might be potentially breaking.
>> > It's possible to opt-in into all current and future 1.0 features by specifying
>> > LIBBPF_STRICT_ALL flag.
>> >
>> > When some of the 1.0 "features" are requested, libbpf APIs might behave
>> > differently. In this patch set a first set of changes are implemented, all
>> > related to the way libbpf returns errors. See individual patches for details.
>> >
>> > Patch #1 adds a no-op libbpf_set_strict_mode() functionality to enable
>> > updating selftests.
>> >
>> > Patch #2 gets rid of all the bad code patterns that will break in libbpf 1.0
>> > (exact -1 comparison for low-level APIs, direct IS_ERR() macro usage to check
>> > pointer-returning APIs for error, etc). These changes make selftest work in
>> > both legacy and 1.0 libbpf modes. Selftests also opt-in into 100% libbpf 1.0
>> > mode to automatically gain all the subsequent changes, which will come in
>> > follow up patches.
>> >
>> > Patch #3 streamlines error reporting for low-level APIs wrapping bpf() syscall.
>> >
>> > Patch #4 streamlines errors for all the rest APIs.
>> >
>> > Patch #5 ensures that BPF skeletons propagate errors properly as well, as
>> > currently on error some APIs will return NULL with no way of checking exact
>> > error code.
>> >
>> >   [0] https://docs.google.com/document/d/1UyjTZuPFWiPFyKk1tV5an11_iaRuec6U-ZESZ54nNTY
>> >
>> > Andrii Nakryiko (5):
>> >   libbpf: add libbpf_set_strict_mode() API to turn on libbpf 1.0
>> >     behaviors
>> >   selftests/bpf: turn on libbpf 1.0 mode and fix all IS_ERR checks
>> >   libbpf: streamline error reporting for low-level APIs
>> >   libbpf: streamline error reporting for high-level APIs
>> >   bpftool: set errno on skeleton failures and propagate errors
>> >
>>
>> LGTM for the series,
>>
>> Acked-by: John Fastabend <john.fastabend@...il.com>
>
> Thanks, John!
>
> Toke, Stanislav, you cared about these aspects of libbpf 1.0 (by
> commenting on the doc itself), do you mind also taking a brief look
> and letting me know if this works for your use cases? Thanks!

Changes LGTM:

Acked-by: Toke Høiland-Jørgensen <toke@...hat.com>

As a side note, the series seems to have been chopped up into individual
emails with no threading; was a bit weird that I had to go hunting for
the individual patches in my mailbox...