linux-kernel - Re: [PATCH v1 1/1] gpiolib: cdev: use !mem_is_zero() instead of memchr

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Message-ID: <20240905011549.GA7299@rigel>
Date: Thu, 5 Sep 2024 09:15:49 +0800
From: Kent Gibson <warthog618@...il.com>
To: Andy Shevchenko <andy.shevchenko@...il.com>
Cc: Bartosz Golaszewski <bartosz.golaszewski@...aro.org>,
	linux-gpio@...r.kernel.org, linux-kernel@...r.kernel.org,
	Bartosz Golaszewski <brgl@...ev.pl>,
	Linus Walleij <linus.walleij@...aro.org>
Subject: Re: [PATCH v1 1/1] gpiolib: cdev: use !mem_is_zero() instead of
 memchr_inv(s, 0, n)

On Wed, Sep 04, 2024 at 12:07:43PM +0300, Andy Shevchenko wrote:
> Use the mem_is_zero() helper where possible.
>
> Signed-off-by: Andy Shevchenko <andy.shevchenko@...il.com>

Somehow I still don't receive mail directly from you, so I only picked
this up via the list. Weird. It should be gmail to gmail, right - WTH?
Unless it isn't - and that is the problem.

I'm ok with the change, though mem_is_zero() hasn't hit any of the trees
I have in front of me, and I had to find the corresponding patch on lore.
Given this is explicitly the use case for it, I would've embedded the
negation in the function and the name, so mem_not_zero() rather than
!mem_is_zero(), as that reads better for me, but ok.

Acked-by: Kent Gibson <warthog618@...il.com>

> ---
>  drivers/gpio/gpiolib-cdev.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/gpio/gpiolib-cdev.c b/drivers/gpio/gpiolib-cdev.c
> index 5aac59de0d76..e98d75dd8acd 100644
> --- a/drivers/gpio/gpiolib-cdev.c
> +++ b/drivers/gpio/gpiolib-cdev.c
> @@ -16,7 +16,6 @@
>  #include <linux/hte.h>
>  #include <linux/interrupt.h>
>  #include <linux/irqreturn.h>
> -#include <linux/kernel.h>
>  #include <linux/kfifo.h>
>  #include <linux/module.h>
>  #include <linux/mutex.h>
> @@ -26,6 +25,7 @@
>  #include <linux/rbtree.h>
>  #include <linux/seq_file.h>
>  #include <linux/spinlock.h>
> +#include <linux/string.h>
>  #include <linux/timekeeping.h>
>  #include <linux/uaccess.h>
>  #include <linux/workqueue.h>
> @@ -1331,7 +1331,7 @@ static int gpio_v2_line_config_validate(struct gpio_v2_line_config *lc,
>  	if (lc->num_attrs > GPIO_V2_LINE_NUM_ATTRS_MAX)
>  		return -EINVAL;
>
> -	if (memchr_inv(lc->padding, 0, sizeof(lc->padding)))
> +	if (!mem_is_zero(lc->padding, sizeof(lc->padding)))
>  		return -EINVAL;
>
>  	for (i = 0; i < num_lines; i++) {
> @@ -1746,7 +1746,7 @@ static int linereq_create(struct gpio_device *gdev, void __user *ip)
>  	if ((ulr.num_lines == 0) || (ulr.num_lines > GPIO_V2_LINES_MAX))
>  		return -EINVAL;
>
> -	if (memchr_inv(ulr.padding, 0, sizeof(ulr.padding)))
> +	if (!mem_is_zero(ulr.padding, sizeof(ulr.padding)))
>  		return -EINVAL;
>
>  	lc = &ulr.config;
> @@ -2516,7 +2516,7 @@ static int lineinfo_get(struct gpio_chardev_data *cdev, void __user *ip,
>  	if (copy_from_user(&lineinfo, ip, sizeof(lineinfo)))
>  		return -EFAULT;
>
> -	if (memchr_inv(lineinfo.padding, 0, sizeof(lineinfo.padding)))
> +	if (!mem_is_zero(lineinfo.padding, sizeof(lineinfo.padding)))
>  		return -EINVAL;
>
>  	desc = gpio_device_get_desc(cdev->gdev, lineinfo.offset);
> --
> 2.46.0
>