linux-kernel - Re: [PATCH] serial: max310x: Use struct_size() in devm

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Date:   Thu, 07 Mar 2019 12:03:15 +0100
From:   Jan Kundrát <jan.kundrat@...net.cz>
To:     "Gustavo A. R. Silva" <gustavo@...eddedor.com>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jiri Slaby <jslaby@...e.com>, <linux-serial@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] serial: max310x: Use struct_size() in devm_kzalloc()

On pátek 4. ledna 2019 22:39:13 CET, 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 = devm_kzalloc(dev, 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 = devm_kzalloc(dev, 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>
> ---
>  drivers/tty/serial/max310x.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
>
> diff --git a/drivers/tty/serial/max310x.c b/drivers/tty/serial/max310x.c
> index 4f479841769a..1d700a8ab517 100644
> --- a/drivers/tty/serial/max310x.c
> +++ b/drivers/tty/serial/max310x.c
> @@ -1197,8 +1197,7 @@ static int max310x_probe(struct device 
> *dev, struct max310x_devtype *devtype,
>  		return PTR_ERR(regmap);
>  
>  	/* Alloc port structure */
> -	s = devm_kzalloc(dev, sizeof(*s) +
> -			 sizeof(struct max310x_one) * devtype->nr, GFP_KERNEL);
> +	s = devm_kzalloc(dev, struct_size(s, p, devtype->nr), GFP_KERNEL);
>  	if (!s) {
>  		dev_err(dev, "Error allocating port structure\n");
>  		return -ENOMEM;

Reviewed-by: Jan Kundrát <jan.kundrat@...net.cz>
Tested-by: Jan Kundrát <jan.kundrat@...net.cz>