Re: [PATCH bpf-next v4 1/2] libbpf: support selective kernel module BTF loading via bpf_object_open_opts

> diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h
> index b965ad571540..838602319da8 100644
> --- a/tools/lib/bpf/libbpf.h
> +++ b/tools/lib/bpf/libbpf.h

[ ... ]

> @@ -224,10 +224,32 @@ struct bpf_object_open_opts {
>  	 * point (/sys/fs/bpf), in case this default behavior is undesirable.
>  	 */
>  	const char *bpf_token_path;
> +	/*
> +	 * Optional list of kernel module names whose BTFs should be loaded.
> +	 * nr_btf_module_names specifies the number of entries in
> +	 * btf_module_names.
> +	 *
> +	 * If btf_module_names is NULL, all module BTFs are loaded,
> +	 * preserving the default behavior. Otherwise, only the BTFs of
> +	 * the listed modules are loaded. A non-NULL btf_module_names
> +	 * with nr_btf_module_names equal to zero means that no module
> +	 * BTFs are loaded.
> +	 *
> +	 * The list must not contain duplicate entries; otherwise
> +	 * -EINVAL is returned.
> +	 *
> +	 * This affects:
> +	 * - BPF CO-RE relocations against types defined in modules;
> +	 * - BTF-based resolution of function attach targets for
> +	 *   fentry/fexit/fmod_ret/freplace/LSM programs;
> +	 * - extern (ksym) resolution for kernel symbols defined in modules.
                   ^^^^

This isn't a bug, but would it be worth adding struct_ops kernel-type
resolution to the "This affects:" list?

find_struct_ops_kern_types() (tools/lib/bpf/libbpf.c:1049) looks up
'bpf_struct_ops_<name>' via find_ksym_btf_id(), which falls back to
obj->btf_modules[] after load_module_btfs().

A struct_ops implementation whose kernel type lives in a module (e.g. a
module-provided tcp_congestion_ops or sched_ext-style struct_ops) will
therefore stop resolving once a filter that omits that module is supplied.

> +	 */
> +	const char **btf_module_names;
> +	size_t nr_btf_module_names;
>
>  	size_t :0;
>  };
> -#define bpf_object_open_opts__last_field bpf_token_path
> +#define bpf_object_open_opts__last_field nr_btf_module_names



---
AI reviewed your patch. Please fix the bug or email reply why it's not a bug.
See: https://github.com/kernel-patches/vmtest/blob/master/ci/claude/README.md

CI run summary: https://github.com/kernel-patches/bpf/actions/runs/32730521630