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From:   Ian Rogers <irogers@google.com>
Date:   Thu, 16 Jun 2022 18:25:18 -0700
Message-ID: <CAP-5=fV1LXNEi3U_RZxt12xPze41W9s27X_Gc6DbY6oDMJ4WvQ@mail.gmail.com>
Subject: Re: [PATCH v2] libbpf: Fix is_pow_of_2
To:     Andrii Nakryiko <andrii.nakryiko@gmail.com>
Cc:     Andrii Nakryiko <andrii@kernel.org>,
        Alexei Starovoitov <ast@kernel.org>, bpf <bpf@vger.kernel.org>,
        Daniel Borkmann <daniel@iogearbox.net>,
        Martin Lau <kafai@fb.com>, Song Liu <songliubraving@fb.com>,
        Networking <netdev@vger.kernel.org>, Yonghong Song <yhs@fb.com>,
        john fastabend <john.fastabend@gmail.com>,
        KP Singh <kpsingh@kernel.org>, Yuze Chi <chiyuze@google.com>,
        open list <linux-kernel@vger.kernel.org>
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On Thu, Jun 16, 2022 at 4:55 PM Andrii Nakryiko
<andrii.nakryiko@gmail.com> wrote:
>
> On Thu, Jun 16, 2022 at 2:07 PM Ian Rogers <irogers@google.com> wrote:
> >
> > On Thu, Jun 16, 2022 at 2:00 PM Andrii Nakryiko
> > <andrii.nakryiko@gmail.com> wrote:
> > >
> > > On Tue, Jun 14, 2022 at 1:41 PM Ian Rogers <irogers@google.com> wrote:
> > > >
> > > > On Fri, Jun 3, 2022 at 11:30 AM <patchwork-bot+netdevbpf@kernel.org> wrote:
> > > > >
> > > > > Hello:
> > > > >
> > > > > This patch was applied to bpf/bpf-next.git (master)
> > > > > by Andrii Nakryiko <andrii@kernel.org>:
> > > > >
> > > > > On Thu,  2 Jun 2022 22:51:56 -0700 you wrote:
> > > > > > From: Yuze Chi <chiyuze@google.com>
> > > > > >
> > > > > > Move the correct definition from linker.c into libbpf_internal.h.
> > > > > >
> > > > > > Reported-by: Yuze Chi <chiyuze@google.com>
> > > > > > Signed-off-by: Yuze Chi <chiyuze@google.com>
> > > > > > Signed-off-by: Ian Rogers <irogers@google.com>
> > > > > >
> > > > > > [...]
> > > > >
> > > > > Here is the summary with links:
> > > > >   - [v2] libbpf: Fix is_pow_of_2
> > > > >     https://git.kernel.org/bpf/bpf-next/c/f913ad6559e3
> > > > >
> > > > > You are awesome, thank you!
> > > >
> > > > Will this patch get added to 5.19?
> > > > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/tools/lib/bpf/libbpf.c#n4948
> > > >
> > >
> > > I've applied it to bpf-next, so as it stands right now - no. Do you
> > > need this for perf?
> >
> > Nope. We carry it as a patch against 5.19 in Google and was surprised
> > to see I didn't need to drop the patch.  Our internal code had
> > encountered the bug, hence needing the fix. I'd expect others could
> > encounter it, but I'm unaware of an issue with it and perf.
> >
>
> So the fix is in Github mirror ([0]) and it is expected that everyone
> is using libbpf based on Github repo, so not sure why you'd care about
> this fix in bpf tree. I somehow assumed that you need it due to perf,
> but was a bit surprised that perf is affected because I don't think
> it's using BPF ringbuf.
>
> So I guess the question I have is why you don't use libbpf from [0]
> and what can be done to switch to the official libbpf repo?
>
>   [0] https://github.com/libbpf/libbpf

Agreed on not following Linus' tree for libbpf. Not sure about having
such an obvious bug in Linus' tree.

Thanks,
Ian

> > Thanks,
> > Ian
> >
> > > > Thanks,
> > > > Ian
> > > >
> > > > > --
> > > > > Deet-doot-dot, I am a bot.
> > > > > https://korg.docs.kernel.org/patchwork/pwbot.html
> > > > >
> > > > >