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

[Gustavo A. R. Silva]

On 4/6/26 17:24, Alexei Starovoitov wrote:
> On Sun, Apr 5, 2026 at 8:27 PM Kees Cook <kees@xxxxxxxxxx> 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@xxxxxxxxxx> 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@xxxxxxxxxx>
> > > > ---
> > > > 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