linux-kernel - Re: [PATCH] gpio: rockchip: fix OF node leak in probe()

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Message-ID: <842861a7-861e-42d5-80c2-854ee22707ec@linaro.org>
Date: Mon, 2 Sep 2024 12:59:37 +0200
From: Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
To: Bartosz Golaszewski <brgl@...ev.pl>
Cc: Linus Walleij <linus.walleij@...aro.org>, Heiko Stuebner
 <heiko@...ech.de>, Jianqun Xu <jay.xu@...k-chips.com>,
 linux-gpio@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
 linux-rockchip@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] gpio: rockchip: fix OF node leak in probe()

On 02/09/2024 12:23, Bartosz Golaszewski wrote:
> On Mon, Aug 26, 2024 at 5:08 PM Krzysztof Kozlowski
> <krzysztof.kozlowski@...aro.org> wrote:
>>
>> Driver code is leaking OF node reference from of_get_parent() in
>> probe().
>>
>> Fixes: 936ee2675eee ("gpio/rockchip: add driver for rockchip gpio")
>> Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
>> ---
>>  drivers/gpio/gpio-rockchip.c | 1 +
>>  1 file changed, 1 insertion(+)
>>
>> diff --git a/drivers/gpio/gpio-rockchip.c b/drivers/gpio/gpio-rockchip.c
>> index 0bd339813110..365ab947983c 100644
>> --- a/drivers/gpio/gpio-rockchip.c
>> +++ b/drivers/gpio/gpio-rockchip.c
>> @@ -713,6 +713,7 @@ static int rockchip_gpio_probe(struct platform_device *pdev)
>>                 return -ENODEV;
>>
>>         pctldev = of_pinctrl_get(pctlnp);
>> +       of_node_put(pctlnp);
>>         if (!pctldev)
>>                 return -EPROBE_DEFER;
>>
>> --
>> 2.43.0
>>
> 
> How about using __free(device_node)?

I can but I find it less readable. Existing code, after my patch, is
pretty straightforward:

        struct device_node *np = dev->of_node;
        struct device_node *pctlnp = of_get_parent(np);
        struct pinctrl_dev *pctldev = NULL;
        ...

        if (!np || !pctlnp)
                return -ENODEV;

        pctldev = of_pinctrl_get(pctlnp);
        of_node_put(pctlnp);
        if (!pctldev)
                return -EPROBE_DEFER;


So __free() would safe only one of_node_put() and grow its scope
significantly. Above pattern - of_get + use + of_node_put - is pretty
self-contained and readable.

Best regards,
Krzysztof