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From:   Zhouyi Zhou <zhouzhouyi@gmail.com>
Date:   Wed, 31 May 2023 11:14:47 +0800
Message-ID: <CAABZP2zvK8_AxuZB0Smsa+L8eJf-_pnNkYF9mAsoHpSO2JZk-A@mail.gmail.com>
Subject: Re: a small question about bpftool struct_ops
To:     Martin KaFai Lau <martin.lau@linux.dev>
Cc:     bpf@vger.kernel.org, linux-kernel <linux-kernel@vger.kernel.org>
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Hi

On Sat, May 20, 2023 at 3:01=E2=80=AFAM Martin KaFai Lau <martin.lau@linux.=
dev> wrote:
>
> On 5/19/23 5:07 AM, Zhouyi Zhou wrote:
> > Dear developers:
> > I compiled bpftool and bpf tests in mainline (2d1bcbc6cd70),
> > but when I invoke:
> > bpftool struct_ops register bpf_cubic.bpf.o
> >
> > the command line fail with:
> > libbpf: struct_ops init_kern: struct tcp_congestion_ops data is not
> > found in struct bpf_struct_ops_tcp_congestion_ops
>
> At the machine trying to register the bpf_cubic, please dump the vmlinux =
btf and
> search for bpf_struct_ops_tcp_congestion_ops and paste it here:
>
> For example:
> #> bpftool btf dump file /sys/kernel/btf/vmlinux
>
> ...
>
> [74578] STRUCT 'bpf_struct_ops_tcp_congestion_ops' size=3D256 vlen=3D3
>          'refcnt' type_id=3D145 bits_offset=3D0
>          'state' type_id=3D74569 bits_offset=3D32
>          'data' type_id=3D6241 bits_offset=3D512
>
Exciting news:
when I construct the kernel package, I found lots of following warnings:
WARN: multiple IDs found for 'task_struct': 241, 21719 - using 241
WARN: multiple IDs found for 'vm_area_struct': 360, 21750 - using 360
WARN: multiple IDs found for 'file': 805, 21789 - using 805
WARN: multiple IDs found for 'cgroup': 666, 21819 - using 666
WARN: multiple IDs found for 'inode': 928, 21936 - using 928
WARN: multiple IDs found for 'path': 960, 21965 - using 960

These warnings lead me to:
Link: https://lore.kernel.org/lkml/ZBovCrMXJk7NPISp@aurel32.net/T/

So, I upgraded my pahole from [1], and construct the kernel package
again, now I can successfully invoke
bpftool struct_ops register bpf_cubic.bpf.o

[1] https://github.com/acmel/dwarves.git

Sorry for the previous noise

and

Thanks again
Best Regards
Zhouyi