Re: [PATCH bpf-next v2 03/10] bpf: Add btf_type_is_arena_ptr()

[Yonghong Song <yonghong.song@linux.dev>]

On 8/25/26 2:59 PM, bot+bpf-ci@kernel.org wrote:
>> bpf: Add btf_type_is_arena_ptr()
>>
>> Simplify btf_scan_type_tags() and added a new helper
>> btf_type_is_arena_ptr(). No functional change.
> This isn't a bug, but could the changelog use the imperative mood
> consistently (e.g., "Simplify ... and add ...")?  Also, could it explain
> why the helper needs external linkage, such as noting that a later patch
> calls it from verifier.c?
>
>> diff --git a/include/linux/btf.h b/include/linux/btf.h
>> index 89d5a5c4f1171..ddd0f4f32d24b 100644
>> --- a/include/linux/btf.h
>> +++ b/include/linux/btf.h
>> @@ -235,6 +235,7 @@ struct btf_record *btf_parse_fields(const struct btf *btf, const struct btf_type
>>   				    u32 field_mask, u32 value_size);
>>   int btf_check_and_fixup_fields(const struct btf *btf, struct btf_record *rec);
>>   bool btf_type_is_void(const struct btf_type *t);
>> +bool btf_type_is_arena_ptr(const struct btf *btf, const struct btf_type *t);
>>   s32 btf_find_by_name_kind(const struct btf *btf, const char *name, u8 kind);
>>   s32 bpf_find_btf_id(const char *name, u32 kind, struct btf **btf_p);
>>   struct btf *btf_get_module_btf(const struct module *module);
>> diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
>> index 47d43eb983a50..280530d25886c 100644
>> --- a/kernel/bpf/btf.c
>> +++ b/kernel/bpf/btf.c
>> @@ -3523,6 +3523,22 @@ static int btf_type_tag_walk(const struct btf *btf,
>>   	return 0;
>>   }
>>
>> +bool btf_type_is_arena_ptr(const struct btf *btf, const struct btf_type *t)
>> +{
>> +	if (!btf_type_is_ptr(t))
>> +		return false;
>> +
>> +	for (t = btf_type_by_id(btf, t->type); btf_type_is_modifier(t);
>> +	     t = btf_type_by_id(btf, t->type)) {
>> +		if (!btf_type_is_type_tag(t) || btf_type_kflag(t))
>> +			continue;
>> +		if (!strcmp(__btf_name_by_offset(btf, t->name_off), "arena"))
>> +			return true;
>> +	}
>> +
>> +	return false;
>> +}
> This isn't a bug, but since btf_type_tag_walk() sits right above this and
> is still used by btf_find_kptr() and friends, could btf_type_is_arena_ptr()
> be expressed in terms of it rather than repeating the modifier/type-tag
> walk?

Okay, will have more information in commit message.

>
> [ ... ]
>
>
> ---
> 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/32899532405