netdev - Re: [PATCH bpf-next v7 3/6] libbpf: Add support for associating BPF program with struct

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Message-ID: <CAEf4BzYaiBYKEvLZk78MMj1R1yjeTZ5P=C7QCrUquh250ENcpA@mail.gmail.com>
Date: Tue, 25 Nov 2025 15:54:07 -0800
From: Andrii Nakryiko <andrii.nakryiko@...il.com>
To: Amery Hung <ameryhung@...il.com>
Cc: bpf@...r.kernel.org, netdev@...r.kernel.org, alexei.starovoitov@...il.com, 
	andrii@...nel.org, daniel@...earbox.net, tj@...nel.org, martin.lau@...nel.org, 
	kernel-team@...a.com
Subject: Re: [PATCH bpf-next v7 3/6] libbpf: Add support for associating BPF
 program with struct_ops

On Fri, Nov 21, 2025 at 3:14 PM Amery Hung <ameryhung@...il.com> wrote:
>
> Add low-level wrapper and libbpf API for BPF_PROG_ASSOC_STRUCT_OPS
> command in the bpf() syscall.
>
> Signed-off-by: Amery Hung <ameryhung@...il.com>
> ---
>  tools/lib/bpf/bpf.c      | 19 +++++++++++++++++++
>  tools/lib/bpf/bpf.h      | 21 +++++++++++++++++++++
>  tools/lib/bpf/libbpf.c   | 31 +++++++++++++++++++++++++++++++
>  tools/lib/bpf/libbpf.h   | 16 ++++++++++++++++
>  tools/lib/bpf/libbpf.map |  2 ++
>  5 files changed, 89 insertions(+)
>

[...]

>
> +int bpf_program__assoc_struct_ops(struct bpf_program *prog, struct bpf_map *map,
> +                                 struct bpf_prog_assoc_struct_ops_opts *opts)
> +{
> +       int prog_fd, map_fd;
> +
> +       prog_fd = bpf_program__fd(prog);
> +       if (prog_fd < 0) {
> +               pr_warn("prog '%s': can't associate BPF program without FD (was it loaded?)\n",
> +                       prog->name);
> +               return -EINVAL;

This is an error return path from the public libbpf API, please use
libbpf_err() everywhere to ensure errno is set. Missed this in earlier
revisions, sorry.

> +       }
> +
> +       if (prog->type == BPF_PROG_TYPE_STRUCT_OPS) {
> +               pr_warn("prog '%s': can't associate struct_ops program\n", prog->name);
> +               return -EINVAL;
> +       }
> +

[...]