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Date:   Fri, 14 Oct 2022 10:30:52 -0300
From:   Arnaldo Carvalho de Melo <acme@kernel.org>
To:     Tejun Heo <tj@kernel.org>
Cc:     Namhyung Kim <namhyung@kernel.org>,
        Zefan Li <lizefan.x@bytedance.com>,
        Johannes Weiner <hannes@cmpxchg.org>, cgroups@vger.kernel.org,
        Jiri Olsa <jolsa@kernel.org>,
        LKML <linux-kernel@vger.kernel.org>,
        linux-perf-users@vger.kernel.org, Song Liu <songliubraving@fb.com>,
        bpf@vger.kernel.org, Andrii Nakryiko <andrii@kernel.org>
Subject: Re: [PATCH v2] perf stat: Support old kernels for bperf cgroup
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Em Fri, Oct 14, 2022 at 10:27:40AM -0300, Arnaldo Carvalho de Melo escreveu:
> Em Tue, Oct 11, 2022 at 06:53:43AM -1000, Tejun Heo escreveu:
> > On Mon, Oct 10, 2022 at 10:28:08PM -0700, Namhyung Kim wrote:
> > > The recent change in the cgroup will break the backward compatiblity in
> > > the BPF program.  It should support both old and new kernels using BPF
> > > CO-RE technique.
> 
> > > Like the task_struct->__state handling in the offcpu analysis, we can
> > > check the field name in the cgroup struct.
>  
> > > Acked-by: Jiri Olsa <jolsa@kernel.org>
> > > Acked-by: Andrii Nakryiko <andrii@kernel.org>
> > > Signed-off-by: Namhyung Kim <namhyung@kernel.org>
>  
> > Applied to cgroup/for-6.1-fixes.
> 
> Hey, I noticed that the perf build is broken for the
> tools/perf/util/bpf_skel/bperf_cgroup.bpf.c skell, so I tried using b4
> on this Namhyung patch, it ended up getting a newer version, by Tejun,
> that mixes up kernel code and tooling, which, when I tried to apply
> upstream didn't work.
> 
> Please try not to mix up kernel and tools/ changes in the same patch to
> avoid these issues.
> 
> Also when changing tools/perf, please CC me.
> 
> I'm now back trying to apply v2 of this patch to see if it fixes my
> build.

Yeah, applying just Namhyung's v2 patch gets perf back building, I'll
keep it there while processing the other patches so that I can test them
all together.

- Arnaldo