linux-kernel - Re: [PATCH] bpf: bpftool: Setting error code in do

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Message-ID: <40064e3d-e8c6-42ee-80e9-a87f4140ecc0@kernel.org>
Date: Mon, 10 Mar 2025 13:28:16 +0000
From: Quentin Monnet <qmo@...nel.org>
To: nswon <swnam0729@...il.com>, Alexei Starovoitov <ast@...nel.org>,
 Daniel Borkmann <daniel@...earbox.net>, Andrii Nakryiko <andrii@...nel.org>,
 Martin KaFai Lau <martin.lau@...ux.dev>, Eduard Zingerman
 <eddyz87@...il.com>, Song Liu <song@...nel.org>,
 Yonghong Song <yonghong.song@...ux.dev>,
 John Fastabend <john.fastabend@...il.com>, KP Singh <kpsingh@...nel.org>,
 Stanislav Fomichev <sdf@...ichev.me>, Hao Luo <haoluo@...gle.com>,
 Jiri Olsa <jolsa@...nel.org>
Cc: bpf@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] bpf: bpftool: Setting error code in do_loader()

2025-03-10 14:25 UTC+0900 ~ nswon <swnam0729@...il.com>
> missing error code in do_loader()
> bpf_object__open_file() failed, but return 0
> This means the command's exit status code was successful, so make sure to return the correct error code.
> 
> Link: https://lore.kernel.org/bpf/d3b5b4b4-19bb-4619-b4dd-86c958c4a367@stanley.mountain/t/#u
> Closes: https://github.com/libbpf/bpftool/issues/156
> Signed-off-by: nswon <swnam0729@...il.com>


Thanks for this!

Others may correct me if I'm wrong, but I think you should sign off with
your full name here (although it doesn't strictly have to be a full
name, the patch submission docs mention in should be a "known identity"
so I'm not sure whether a GitHub handle, for example, is acceptable).


> ---
>  tools/bpf/bpftool/prog.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/tools/bpf/bpftool/prog.c b/tools/bpf/bpftool/prog.c
> index e71be67f1d86..641802e308f4 100644
> --- a/tools/bpf/bpftool/prog.c
> +++ b/tools/bpf/bpftool/prog.c
> @@ -1928,6 +1928,7 @@ static int do_loader(int argc, char **argv)
>  
>  	obj = bpf_object__open_file(file, &open_opts);
>  	if (!obj) {
> +		err = libbpf_get_error(obj);


This is the correct way to retrieve the error code, but given that
bpftool does nothing with this error code, could we instead simply
return -1 to remain consistent with the other locations where we call
bpf_object__open_file() in the tool, please?

Thanks,
Quentin