linux-kernel - Re: [PATCH v1 4/5] gpio: rockchip: avoid division by zero

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Message-ID: <CAMRc=MdjazVyck=KDqs-zUVwzzRhFFF7e4Gh5Sk9LYzv5am2pw@mail.gmail.com>
Date: Fri, 16 Aug 2024 11:51:35 +0200
From: Bartosz Golaszewski <brgl@...ev.pl>
To: Ye Zhang <ye.zhang@...k-chips.com>
Cc: linus.walleij@...aro.org, heiko@...ech.de, linux-gpio@...r.kernel.org, 
	linux-arm-kernel@...ts.infradead.org, linux-rockchip@...ts.infradead.org, 
	linux-kernel@...r.kernel.org, tao.huang@...k-chips.com, 
	finley.xiao@...k-chips.com, tim.chen@...k-chips.com, 
	elaine.zhang@...k-chips.com
Subject: Re: [PATCH v1 4/5] gpio: rockchip: avoid division by zero

On Thu, Aug 15, 2024 at 9:17 AM Ye Zhang <ye.zhang@...k-chips.com> wrote:
>
> If the clk_get_rate return '0', it will happen division by zero.
>

This looks like a backportable fix. Please add a Fixes: tag and move
the commit to the first place in the series so that it can be sent for
v6.11 and stable already.

> Signed-off-by: Ye Zhang <ye.zhang@...k-chips.com>
> ---
>  drivers/gpio/gpio-rockchip.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpio/gpio-rockchip.c b/drivers/gpio/gpio-rockchip.c
> index 8949324ed816..03e949b0a344 100644
> --- a/drivers/gpio/gpio-rockchip.c
> +++ b/drivers/gpio/gpio-rockchip.c
> @@ -212,8 +212,10 @@ static int rockchip_gpio_set_debounce(struct gpio_chip *gc,
>         if (bank->gpio_type == GPIO_TYPE_V2 && !IS_ERR(bank->db_clk)) {
>                 div_debounce_support = true;
>                 freq = clk_get_rate(bank->db_clk);
> +               if (!freq)
> +                       return -EINVAL;

Newline here.

>                 max_debounce = (GENMASK(23, 0) + 1) * 2 * 1000000 / freq;
> -               if (debounce > max_debounce)
> +               if ((unsigned long)debounce > max_debounce)

This is a separate change, please put it into a different commit.

Bart

>                         return -EINVAL;
>
>                 div = debounce * freq;
> --
> 2.34.1
>