Re: [PATCH bpf-next v3 04/24] bpf: Set sub->arg_cnt earlier in btf_prepare_func_args()

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

On 5/11/26 8:19 AM, bot+bpf-ci@kernel.org wrote:
>> diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
>> index 77af44d8a3ad..a33a5b4122f8 100644
>> --- a/kernel/bpf/btf.c
>> +++ b/kernel/bpf/btf.c
>> @@ -7880,6 +7880,7 @@ int btf_prepare_func_args(struct bpf_verifier_env *env, int subprog)
>>   	}
>>   	args = (const struct btf_param *)(t + 1);
>>   	nargs = btf_type_vlen(t);
>> +	sub->arg_cnt = nargs;
>>   	if (nargs > MAX_BPF_FUNC_REG_ARGS) {
>>   		if (!is_global)
>>   			return -EINVAL;
>> @@ -8067,7 +8068,6 @@ int btf_prepare_func_args(struct bpf_verifier_env *env, int subprog)
>>   		return -EINVAL;
>>   	}
>>
>> -	sub->arg_cnt = nargs;
>>   	sub->args_cached = true;
>>
>>   	return 0;
>
> ---
> AI reviewed your patch. Please fix the bug or email reply why it's not a bug.

In v3, for the *main* program, we have the following:

                 /* if main BPF program has associated BTF info, validate that
                  * it's matching expected signature, and otherwise mark BTF
                  * info for main program as unreliable
                  */
                 if (env->prog->aux->func_info_aux) {
                         ret = btf_prepare_func_args(env, 0);
                         if (ret || sub->arg_cnt != 1 || sub->args[0].arg_type != ARG_PTR_TO_CTX) {
                                 env->prog->aux->func_info_aux[0].unreliable = true;
                                 sub->arg_cnt = 1;
                                 sub->stack_arg_cnt = 0;
                         }
                 }

Since sub->arg_cnt and sub->stack_arg_cnt is set here for the main program,
patch #4 is not needed any more.


> See: https://github.com/kernel-patches/vmtest/blob/master/ci/claude/README.md
>
> CI run summary: https://github.com/kernel-patches/bpf/actions/runs/25652623893