Re: [PATCH v2 bpf-next 01/18] bpf: Add BTF ID sets for fmod_ret targets

[bot+bpf-ci]

> bpf: Add BTF ID sets for fmod_ret targets

TL;DR: Nits only in resolve_btfids: a comment may misleadingly suggest entries
with a missing function are rejected (they only warn), and a new outer "off"
is shadowed by the inner one.

> diff --git a/tools/bpf/resolve_btfids/main.c b/tools/bpf/resolve_btfids/main.c
> --- a/tools/bpf/resolve_btfids/main.c
> +++ b/tools/bpf/resolve_btfids/main.c

[ ... ]

> @@ -1344,7 +1355,16 @@ static bool is_arena_param(const struct btf *btf, const struct btf_param *param)
>  	       param_name_has_suffix(name, PARAM_SUFFIX_ARENA_NULLABLE);
>  }
>  
> -static int collect_kfuncs(struct object *obj, struct btf2btf_context *ctx)
> +typedef int (*set_func_fn)(struct btf2btf_context *ctx, const char *name,
> +			   u32 btf_id, u32 flags);
> +
> +/*
> + * Call FN for each function in the BTF ID sets which have SET_FLAG set. Reject
> + * an entry with flags other than ALLOWED_FLAGS, also if its function is missing.
> + */

This isn't a bug, but could this read "even if its function is missing"?
As written it can suggest that entries with a missing function are
rejected, while collect_set_funcs() only prints a WARN, increments
warnings and continues to the next entry.

[ ... ]

> @@ -1356,24 +1376,39 @@ static int collect_kfuncs(struct object *obj, struct btf2btf_context *ctx)
>  	for (next = rb_first(&obj->sets); next; next = rb_next(next)) {
>  		struct btf_id_set8 *set8;
>  		struct btf_id *set_id;
> -		u64 set_addr;
> +		u64 set_addr, off;

[ ... ]

>  		for (u32 i = 0; i < set_id->cnt; i++) {
>  			size_t off = (char *)&set8->pairs[i] - (char *)set8;
>  			const char *name = find_name_by_addr(obj, set_addr + off);

This isn't a bug, but would a distinct name for the new outer offset, for
example set_off, make it clearer which offset "set_addr + off" uses here?

The inner "size_t off" (offset of a pair within the set) now shadows the
outer "off" (offset of the set within .BTF_ids), and the inner declaration
would trigger -Wshadow.


---
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/42662799554