linux-kernel - Re: [PATCH 2/3] gpio: pxa: Fix return value of pxa_gpio

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Date:   Wed, 27 May 2020 20:26:07 +0200
From:   Robert Jarzmik <robert.jarzmik@...e.fr>
To:     Tiezhu Yang <yangtiezhu@...ngson.cn>
Cc:     Linus Walleij <linus.walleij@...aro.org>,
        Bartosz Golaszewski <bgolaszewski@...libre.com>,
        Ray Jui <rjui@...adcom.com>,
        bcm-kernel-feedback-list@...adcom.com, linux-gpio@...r.kernel.org,
        linux-kernel@...r.kernel.org, Xuefeng Li <lixuefeng@...ngson.cn>
Subject: Re: [PATCH 2/3] gpio: pxa: Fix return value of pxa_gpio_probe()

Tiezhu Yang <yangtiezhu@...ngson.cn> writes:

> On 05/23/2020 03:07 AM, Robert Jarzmik wrote:
>> Tiezhu Yang <yangtiezhu@...ngson.cn> writes:
>>
>>> When call function devm_platform_ioremap_resource(), we should use IS_ERR()
>>> to check the return value and return PTR_ERR() if failed.
>>>
>>> Fixes: 542c25b7a209 ("drivers: gpio: pxa: use devm_platform_ioremap_resource()")
>>> Signed-off-by: Tiezhu Yang <yangtiezhu@...ngson.cn>
>>> ---
>>>   drivers/gpio/gpio-pxa.c | 4 ++--
>>>   1 file changed, 2 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/drivers/gpio/gpio-pxa.c b/drivers/gpio/gpio-pxa.c
>>> index 1361270..0cb6600 100644
>>> --- a/drivers/gpio/gpio-pxa.c
>>> +++ b/drivers/gpio/gpio-pxa.c
>>> @@ -660,8 +660,8 @@ static int pxa_gpio_probe(struct platform_device *pdev)
>>>   	pchip->irq1 = irq1;
>>>     	gpio_reg_base = devm_platform_ioremap_resource(pdev, 0);
>>> -	if (!gpio_reg_base)
>>> -		return -EINVAL;
>>> +	if (IS_ERR(gpio_reg_base))
>>> +		return PTR_ERR(gpio_reg_base);
>> As far as I know, devm_platform_ioremap_resource() could return NULL which is
>> not handled by this test (unless __devm_ioremap() semantics changed since I had
>> a look).
>
> Hi Robert,
>
> In the function __devm_ioremap_resource(), if __devm_ioremap returns NULL,
> it will return IOMEM_ERR_PTR(-ENOMEM).
>
> devm_platform_ioremap_resource()
>         devm_ioremap_resource()
>                 __devm_ioremap_resource()
>                        __devm_ioremap()
>
> static void __iomem *
> __devm_ioremap_resource(struct device *dev, const struct resource *res,
>             enum devm_ioremap_type type)
> {
> ...
>     dest_ptr = __devm_ioremap(dev, res->start, size, type);
>     if (!dest_ptr) {
>         dev_err(dev, "ioremap failed for resource %pR\n", res);
>         devm_release_mem_region(dev, res->start, size);
>         dest_ptr = IOMEM_ERR_PTR(-ENOMEM);
>     }
>
>     return dest_ptr;
> }
>
> And also, we can see the comment of devm_ioremap_resource():
>
> Usage example:
>
>         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>         base = devm_ioremap_resource(&pdev->dev, res);
>         if (IS_ERR(base))
>                 return PTR_ERR(base);
>
>>
>> Therefore, this patch is incorrect, or rather incomplete.
>
> So I think this patch is correct, do I miss something?
You're right, my bad, didn't see the test in __devm_ioremap_resource().

Cheers.

-- 
Robert