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Date: Tue, 27 Mar 2018 15:41:23 +0200
From: Linus Walleij <>
To: Laura Abbott <>
Cc: Phil Reid <>, Kees Cook <>, 
	Patrice Chotard <>, 
	"open list:GPIO SUBSYSTEM" <>, 
	"" <>,
Subject: Re: [PATCHv2 4/4] gpio: Remove VLA from stmpe driver

Hi Laura,

sorry for slow response :/

On Thu, Mar 22, 2018 at 10:43 PM, Laura Abbott <> wrote:
> On 03/18/2018 06:29 PM, Phil Reid wrote:
>> On 16/03/2018 02:00, Laura Abbott wrote:
>>> The new challenge is to remove VLAs from the kernel
>>> (see
>>> This patch replaces a VLA with an appropriate call to kmalloc_array.
>>> Signed-off-by: Laura Abbott <>
>>> ---
>>> v2: Switch to GFP_KERNEL. There was some discussion about if we should
>>> be doing the allocation at all but given a) the allocation is pretty
>>> small and b) we can possibly take a mutex in a called function I think
>>> this is fine.
>> I still think it's a bad idea. It's simple to preallocate the buffer.
>> But it's up to the maintainer.
> I'd feel a lot more confident about doing the global buffer with
> guidance from the maintainer. But looking at the platform data, the
> maximum number of GPIOs is 24, or 3 banks. Maybe we should just always
> stack allocate the maximum since it's fairly small.

Either way works fine, global (in the state container struct stmpe_gpio)
or stack allocation for 24 bits.

I guess I am maintainer for this, I can test it at least.

Linus Walleij

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