linux-kernel - Re: [PATCH v2] gpio: merrifield: check the return value of devm

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Message-ID: <Ye62z5jB+25ocAeT@smile.fi.intel.com>
Date:   Mon, 24 Jan 2022 16:25:19 +0200
From:   Andy Shevchenko <andriy.shevchenko@...el.com>
To:     xkernel.wang@...mail.com
Cc:     andy@...nel.org, linus.walleij@...aro.org, brgl@...ev.pl,
        linux-gpio@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] gpio: merrifield: check the return value of
 devm_kstrdup()

On Mon, Jan 17, 2022 at 03:06:06PM +0800, xkernel.wang@...mail.com wrote:
> From: Xiaoke Wang <xkernel.wang@...mail.com>
> 
> devm_kstrdup() returns pointer to allocated string on success, NULL on
> failure. So it is better to check the return value of it.
> 
> Before, if devm_kstrdup() fails, pinctrl_dev_name will be NULL, then the
> retval below will be a negative error-code(inside gpiochip_add_pin_range(),
> pinctrl_find_and_add_gpio_range()->get_pinctrl_dev_from_devname() will
> finally check pinctrl_dev_name and return error), so the failure of
> devm_kstrdup() can be only implicitly caught after a long call chain.
> While this patch is to explicitly catch the failure in time.
> > retval = gpiochip_add_pin_range(&priv->chip, pinctrl_dev_name,
> >				  range->gpio_base,
> >				  range->pin_base,
> >				  range->npins);
> > if (retval) {
> > 	dev_err(priv->dev, "failed to add GPIO pin range\n");
> > 	return retval;
> > }

Pushed to my review and testing queue, thanks!

> Signed-off-by: Xiaoke Wang <xkernel.wang@...mail.com>
> ---
> Changelogs:
> v1 -> v2: update the commit message.
>  drivers/gpio/gpio-merrifield.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/gpio/gpio-merrifield.c b/drivers/gpio/gpio-merrifield.c
> index 42c4d9d..f3d1bae 100644
> --- a/drivers/gpio/gpio-merrifield.c
> +++ b/drivers/gpio/gpio-merrifield.c
> @@ -409,6 +409,9 @@ static int mrfld_gpio_add_pin_ranges(struct gpio_chip *chip)
>  	int retval;
>  
>  	pinctrl_dev_name = mrfld_gpio_get_pinctrl_dev_name(priv);
> +	if (!pinctrl_dev_name)
> +		return -ENOMEM;
> +
>  	for (i = 0; i < ARRAY_SIZE(mrfld_gpio_ranges); i++) {
>  		range = &mrfld_gpio_ranges[i];
>  		retval = gpiochip_add_pin_range(&priv->chip, pinctrl_dev_name,
> -- 

-- 
With Best Regards,
Andy Shevchenko