linux-kernel - Re: [PATCH] Input: tca6416-keypad: use struct

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Message-ID: <20190112014726.GB122403@dtor-ws>
Date:   Fri, 11 Jan 2019 17:47:26 -0800
From:   Dmitry Torokhov <dmitry.torokhov@...il.com>
To:     "Gustavo A. R. Silva" <gustavo@...eddedor.com>
Cc:     linux-input@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] Input: tca6416-keypad: use struct_size() in kzalloc()

On Tue, Jan 08, 2019 at 09:28:16AM -0600, Gustavo A. R. Silva wrote:
> One of the more common cases of allocation size calculations is finding the
> size of a structure that has a zero-sized array at the end, along with memory
> for some number of elements for that array. For example:
> 
> struct foo {
>     int stuff;
>     void *entry[];
> };
> 
> instance = kzalloc(sizeof(struct foo) + sizeof(void *) * count, GFP_KERNEL);
> 
> Instead of leaving these open-coded and prone to type mistakes, we can now
> use the new struct_size() helper:
> 
> instance = kzalloc(struct_size(instance, entry, count), GFP_KERNEL);
> 
> This code was detected with the help of Coccinelle.
> 
> Signed-off-by: Gustavo A. R. Silva <gustavo@...eddedor.com>

Applied, thank you.

> ---
>  drivers/input/keyboard/tca6416-keypad.c | 4 +---
>  1 file changed, 1 insertion(+), 3 deletions(-)
> 
> diff --git a/drivers/input/keyboard/tca6416-keypad.c b/drivers/input/keyboard/tca6416-keypad.c
> index dc983ab6c0ad..cdeef180aead 100644
> --- a/drivers/input/keyboard/tca6416-keypad.c
> +++ b/drivers/input/keyboard/tca6416-keypad.c
> @@ -219,9 +219,7 @@ static int tca6416_keypad_probe(struct i2c_client *client,
>  		return -EINVAL;
>  	}
>  
> -	chip = kzalloc(sizeof(struct tca6416_keypad_chip) +
> -		       pdata->nbuttons * sizeof(struct tca6416_button),
> -		       GFP_KERNEL);
> +	chip = kzalloc(struct_size(chip, buttons, pdata->nbuttons), GFP_KERNEL);
>  	input = input_allocate_device();
>  	if (!chip || !input) {
>  		error = -ENOMEM;
> -- 
> 2.20.1
> 

-- 
Dmitry