Re: [PATCH v2][next] bpf: Avoid thousands of -Wflex-array-members-not-at-end warnings

["Gustavo A. R. Silva" <gustavo@embeddedor.com>]

On 4/6/26 17:24, Alexei Starovoitov wrote:
> On Sun, Apr 5, 2026 at 8:27 PM Kees Cook <kees@kernel.org> wrote:
>>
>> On Sun, Apr 05, 2026 at 07:44:51PM -0700, Alexei Starovoitov wrote:
>>> On Mon, Mar 30, 2026 at 3:39 PM Gustavo A. R. Silva
>>> <gustavoars@kernel.org> wrote:
>>>>
>>>> Apparently, struct bpf_empty_prog_array exists entirely to populate a
>>>> single element of "items" in a global variable. "null_prog" is only
>>>> used during the initializer.
>>>>
>>>> None of this is needed; globals will be correctly sized with an array
>>>> initializer of a flexible-array member.
>>>>
>>>> So, remove struct bpf_empty_prog_array and adjust the rest of the code,
>>>> accordingly.
>>>>
>>>> With these changes, fix the following warnings:
>>>>
>>>> 7659 ./include/linux/bpf.h:2369:31: warning: structure containing a flexible array member is not at the end of another structure [-Wflex-array-member-not-at-end]
>>>>
>>>> Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
>>>> ---
>>>> Changes in v2:
>>>>   - Remove struct bpf_empty_prog_array. (Kees)
>>>
>>> Kees,
>>>
>>> It really bothers me that you ask people to clean up
>>> warnings for the sake of removing warnings.
>>
>> It's not for the sake of warnings; this is to remove the ambiguously
>> sized objects (i.e. structs that the compiler cannot reason about the
>> size of).
> 
> I read through the AI debug logs. What steps it took to reason that
> the fix is correct, and it convinced me that I'm wrong.

What prompted you to think this was a "ticking time bomb"?

> Applied.

Thanks

-Gustavo