Re: [PATCHv9] gpio: Remove VLA from gpiolib

From: Linus Walleij
Date: Wed May 23 2018 - 07:09:39 EST


On Mon, May 21, 2018 at 7:57 PM, Laura Abbott <labbott@xxxxxxxxxx> wrote:

> The new challenge is to remove VLAs from the kernel
> (see https://lkml.org/lkml/2018/3/7/621) to eventually
> turn on -Wvla.
>
> Using a kmalloc array is the easy way to fix this but kmalloc is still
> more expensive than stack allocation. Introduce a fast path with a
> fixed size stack array to cover most chip with gpios below some fixed
> amount. The slow path dynamically allocates an array to cover those
> chips with a large number of gpios.
>
> Reviewed-by: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>
> Reviewed-by: Phil Reid <preid@xxxxxxxxxxxxxxxxx>
> Reviewed-and-tested-by: Lukas Wunner <lukas@xxxxxxxxx>
> Signed-off-by: Lukas Wunner <lukas@xxxxxxxxx>
> Signed-off-by: Laura Abbott <labbott@xxxxxxxxxx>
> ---
> v9: switch to bitmap_zero

This v9 applied with Andy's review tag on top and pushed to
the servers for testing!

THANKS A LOT for your tireless work on this, it looks really
really good now, and as it seems we cleaned up some other
code on the way.

Yours,
Linus Walleij