Re: [PATCHv3] gpio: virtio: remove one kcalloc

[Linus Walleij <linusw@kernel.org>]

On Tue, Mar 17, 2026 at 9:49 AM Viresh Kumar <viresh.kumar@linaro.org> wrote:
> On 16-03-26, 15:00, Linus Walleij wrote:
> > On Fri, Mar 13, 2026 at 7:09 AM Viresh Kumar <viresh.kumar@linaro.org> wrote:
> >
> > > I wonder if it is worth it anymore. Why combining allocations is better when we
> > > are ending up using more memory ?
> >
> > For the same reason we are starting to use Rust in the kernel, despite
> > it sometimes will take more memory essentially. __counted_by() enforce
> > the same type of runtime size checks as Rust do on arrays.
>
> Right. I don't have any issue with __counted_by(). It does the right thing for
> flexible length arrays. But we don't need a flexible length array here and so my
> question.

So why check for something that "can't go wrong".

IIUC it still removes undefined behaviour from the object code.

If someone managed to compromise the kernel using return-oriented programming
they cannot call back into this function to overwrite the memory
beyond where the
array is stored, because the runtime checks will block this.

But Kees & Gustavo can tell if I understand this correctly.

Yours,
Linus Walleij