On Wed, 2026-08-19 at 17:04 +0800, Fuyu Zhao wrote:
Overall the logic seem to be fine for me, please find a few comments below.
...
> diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
> index 514e4e9daa82..37934ca49dd7 100644
> --- a/tools/lib/bpf/libbpf.c
> +++ b/tools/lib/bpf/libbpf.c
> @@ -779,6 +779,13 @@ struct bpf_object {
> char *token_path;
> int token_fd;
>
> + /* kernel module BTFs to load, as specified via bpf_object_open_opts */
> + struct {
> + char **names;
> + size_t nr_names;
> + struct hashmap *names_map;
We already have a strset type, please use it instead of a direct
hashmap reference. This would remove the need for `names` field
and simplify the bpf_object__init_kmod_btfs() function.
Also, do you expect `nr_names` to be high?
If not, wouldn't plain array search be simpler/faster here?
> + } *kmod_btfs;
Why indirection?
Also, I agree with the bot here, prior fields use "module" in the name,
so something like "btf_module_names" or similar is a better fit.
Same for publicly visible 'opts' name.
...
> +static int bpf_object__init_kmod_btfs(struct bpf_object *obj,
> + const struct bpf_object_open_opts *opts)
> +{
> + const char **kmod_btf_names;
> + size_t i, kmod_btf_names_cnt;
> + int err;
> +
> + kmod_btf_names = OPTS_GET(opts, kmod_btf_names, NULL);
> + if (!kmod_btf_names)
> + return 0;
> +
> + kmod_btf_names_cnt = OPTS_GET(opts, kmod_btf_names_cnt, 0);
> + if (!kmod_btf_names_cnt) {
> + pr_warn("kmod_btf_names_cnt must be set when kmod_btf_names is
> provided\n");
> + return -EINVAL;
I kinda agree with the bot here, why disallow an empty filter here?
> + }
> +
> + obj->kmod_btfs = calloc(1, sizeof(*obj->kmod_btfs));
> + if (!obj->kmod_btfs)
> + return -ENOMEM;
> +
> + obj->kmod_btfs->names = calloc(kmod_btf_names_cnt, sizeof(char *));
> + if (!obj->kmod_btfs->names) {
> + err = -ENOMEM;
> + goto err_out;
> + }
> +
> + obj->kmod_btfs->names_map = hashmap__new(mod_name_hash_fn,
> + mod_name_equal_fn, NULL);
> + if (IS_ERR(obj->kmod_btfs->names_map)) {
> + err = PTR_ERR(obj->kmod_btfs->names_map);
> + obj->kmod_btfs->names_map = NULL;
> + goto err_out;
> + }
> +
> + for (i = 0; i < kmod_btf_names_cnt; i++) {
> + size_t idx = obj->kmod_btfs->nr_names;
> +
> + if (!kmod_btf_names[i] || !kmod_btf_names[i][0]) {
> + pr_warn("invalid kernel module BTF name at index
> %zu\n", i);
> + err = -EINVAL;
> + goto err_out;
> + }
> +
> + obj->kmod_btfs->names[idx] = strdup(kmod_btf_names[i]);
> + if (!obj->kmod_btfs->names[idx]) {
> + err = -ENOMEM;
> + goto err_out;
> + }
> +
> + err = hashmap__add(obj->kmod_btfs->names_map,
> + obj->kmod_btfs->names[idx], 0);
> + if (err) {
> + zfree(&obj->kmod_btfs->names[idx]);
> + if (err == -EEXIST) {
> + pr_warn("duplicate kmod BTF name '%s'
> ignored\n",
> + kmod_btf_names[i]);
Nit: I'd downgrade this to debug level, if at all.
> + continue;
> + }
> + goto err_out;
> + }
> + obj->kmod_btfs->nr_names++;
> + }
> + return 0;
> +
> +err_out:
> + bpf_object__free_kmod_btfs(obj);
> + return err;
> +}
...
> @@ -8515,6 +8645,7 @@ static struct bpf_object *bpf_object_open(const char
> *path, const void *obj_buf,
> err = err ? : bpf_object__init_maps(obj, opts);
> err = err ? : bpf_object_init_progs(obj, opts);
> err = err ? : bpf_object__collect_relos(obj);
> + err = err ? : bpf_object__init_kmod_btfs(obj, opts);
Nit: all other options are collected before bpf_object__elf_init()
call just above.
> if (err)
> goto out;
>
...
> diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h
> index b965ad571540..2f8ff6d2d3df 100644
> --- a/tools/lib/bpf/libbpf.h
> +++ b/tools/lib/bpf/libbpf.h
> @@ -224,10 +224,24 @@ 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.
> + * kmod_btf_names_cnt specifies the number of entries in
> + * kmod_btf_names.
> + *
> + * If kmod_btf_names is NULL, all module BTFs are loaded, preserving
> + * the default behavior. Otherwise, only the specified module BTFs
> + * are loaded.
> + *
> + * kmod_btf_names_cnt must be non-zero when kmod_btf_names is
> + * non-NULL; otherwise -EINVAL is returned.
Nit: please add a complete list of behaviors this affects, e.g. CO-RE,
fentry/fexit resolution, etc.
> + */
> + const char **kmod_btf_names;
> + size_t kmod_btf_names_cnt;
>
> size_t :0;
> };
> -#define bpf_object_open_opts__last_field bpf_token_path
> +#define bpf_object_open_opts__last_field kmod_btf_names_cnt
>
> /**
> * @brief **bpf_object__open()** creates a bpf_object by opening
