Re: [PATCH bpf-next v4 3/8] resolve_btfids: Introduce enum btf_id_kind

bot+bpf-ci
2025-12-18T00:47:30Z

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> diff --git a/tools/bpf/resolve_btfids/main.c b/tools/bpf/resolve_btfids/main.c
> index b4caae1170dd..da8c7d127632 100644
> --- a/tools/bpf/resolve_btfids/main.c
> +++ b/tools/bpf/resolve_btfids/main.c

[ ... ]

> @@ -260,22 +279,36 @@ static char *get_id(const char *prefix_end)
> return id;
> }
>
> -static struct btf_id *add_set(struct object *obj, char *name, bool is_set8)
> +static struct btf_id *add_set(struct object *obj, char *name, enum btf_id_kind kind)
> {
> + int len = strlen(name);
> + int prefixlen;
> + char *id;
> +
> /*
> * __BTF_ID__set__name
> * name = ^
> * id = ^
> */
> - char *id = name + (is_set8 ? sizeof(BTF_SET8 "__") : sizeof(BTF_SET "__")) - 1;
> - int len = strlen(name);
> + switch (kind) {
> + case BTF_ID_KIND_SET:
> + prefixlen = sizeof(BTF_SET "__") - 1;
> + break;
> + case BTF_ID_KIND_SET8:
> + prefixlen = sizeof(BTF_SET8 "__") - 1;
> + break;
> + default:
> + pr_err("Unexpected kind %d passed to %s() for symbol %s\n", kind, __func__, name);
> + return NULL;
> + }
> +
> + id = name + prefixlen - 1;

Is this off by one? The original code computed:

id = name + sizeof(BTF_SET "__") - 1

For BTF_SET ("set"), this gives: name + sizeof("set__") - 1 = name + 6 - 1 = name + 5

The new code computes:

prefixlen = sizeof(BTF_SET "__") - 1 = 6 - 1 = 5
id = name + prefixlen - 1 = name + 5 - 1 = name + 4

The -1 appears to be applied twice now, once in the prefixlen assignment and
again when computing id. Should this line be:

id = name + prefixlen;

> if (id >= name + len) {
> pr_err("FAILED to parse set name: %s\n", name);
> return NULL;
> }
>
> - return btf_id__add(&obj->sets, id, true);
> + return btf_id__add_unique(&obj->sets, id, kind);
> }

---
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/20321956014