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Date:   Thu, 5 May 2022 21:32:17 -0400
From:   Milan Landaverde <milan@mdaverde.com>
To:     Larysa Zaremba <larysa.zaremba@intel.com>
Cc:     Alexei Starovoitov <ast@kernel.org>,
        Daniel Borkmann <daniel@iogearbox.net>,
        Andrii Nakryiko <andrii@kernel.org>, netdev@vger.kernel.org,
        bpf@vger.kernel.org, linux-kernel@vger.kernel.org,
        Martin KaFai Lau <kafai@fb.com>,
        Song Liu <songliubraving@fb.com>, Yonghong Song <yhs@fb.com>,
        Maciej Fijalkowski <maciej.fijalkowski@intel.com>,
        Alexander Lobakin <alexandr.lobakin@intel.com>
Subject: Re: [PATCH] bpftool: Use sysfs vmlinux when dumping BTF by ID
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References: <20220428110839.111042-1-larysa.zaremba@intel.com>
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Hello! Just ran into this. I think we also need to pass in errno
here to strerror instead of err:

On Thu, Apr 28, 2022 at 01:08:40PM +0200, Larysa Zaremba wrote:
>  		if (err) {
>  			p_err("get btf by id (%u): %s", btf_id, strerror(err));
>  			goto done;
>

Currently, the error output without a base btf reads:

$ bpftool btf dump id 816
Error: get btf by id (816): Unknown error -22

When it should (or at least intends to) read:

$ bpftool btf dump id 816
Error: get btf by id (816): Invalid argument

I was going to send this patch but if a v2 is going to be sent, figured
I mention it. Thanks!