[PATCH] spi: davinci: Remove dead code in `davinci_spi_probe()`

[PATCH] spi: davinci: Remove dead code in `davinci_spi_probe()`

[Li Ningke]

Smatch complains that
drivers/spi/spi-davinci.c:915 davinci_spi_probe() warn:
platform_get_irq() does not return zero

There is no need to check whether the return value is zero as
`platform_get_irq()` only returns non-zero IRQ number on success
or negative error number on failure, removing them to solve this
problem.

Signed-off-by: Li Ningke <lnk_01@hust.edu.cn>
Reviewed-by: Dongliang Mu <dzm91@hust.edu.cn>
---
The issue is found by static analysis and the patch remains untested.
---
 drivers/spi/spi-davinci.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/drivers/spi/spi-davinci.c b/drivers/spi/spi-davinci.c
index d112c2cac042..fdb241e3a7bf 100644
--- a/drivers/spi/spi-davinci.c
+++ b/drivers/spi/spi-davinci.c
@@ -912,8 +912,6 @@ static int davinci_spi_probe(struct platform_device *pdev)
 	init_completion(&dspi->done);
 
 	ret = platform_get_irq(pdev, 0);
-	if (ret == 0)
-		ret = -EINVAL;
 	if (ret < 0)
 		goto free_master;
 	dspi->irq = ret;
-- 
2.34.1

Re: [PATCH] spi: davinci: Remove dead code in `davinci_spi_probe()`

[Mark Brown]

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On Sun, Apr 23, 2023 at 03:24:46AM +0000, Li Ningke wrote:
> Smatch complains that
> drivers/spi/spi-davinci.c:915 davinci_spi_probe() warn:
> platform_get_irq() does not return zero
> 
> There is no need to check whether the return value is zero as
> `platform_get_irq()` only returns non-zero IRQ number on success
> or negative error number on failure, removing them to solve this
> problem.

Is that check valid?  0 was a valid interrupt for some architectures...

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Re: [PATCH] spi: davinci: Remove dead code in `davinci_spi_probe()`

[Dongliang Mu]

On 2023/4/24 19:48, Mark Brown wrote:
> On Sun, Apr 23, 2023 at 03:24:46AM +0000, Li Ningke wrote:
>> Smatch complains that
>> drivers/spi/spi-davinci.c:915 davinci_spi_probe() warn:
>> platform_get_irq() does not return zero
>>
>> There is no need to check whether the return value is zero as
>> `platform_get_irq()` only returns non-zero IRQ number on success
>> or negative error number on failure, removing them to solve this
>> problem.
> Is that check valid?  0 was a valid interrupt for some architectures...

We just follow the comments of platform_get_irq().

/**
  * platform_get_irq - get an IRQ for a device
  * @dev: platform device
  * @num: IRQ number index
  *
  * Gets an IRQ for a platform device and prints an error message if 
finding the
  * IRQ fails. Device drivers should check the return value for errors 
so as to
  * not pass a negative integer value to the request_irq() APIs.
  *
  * For example::
  *
  *              int irq = platform_get_irq(pdev, 0);
  *              if (irq < 0)
  *                      return irq;
  *
  * Return: non-zero IRQ number on success, negative error number on 
failure.
  */
int platform_get_irq(struct platform_device *dev, unsigned int num)
{
         int ret;

         ret = platform_get_irq_optional(dev, num);
         if (ret < 0)
                 return dev_err_probe(&dev->dev, ret,
                                      "IRQ index %u not found\n", num);

         return ret;
}

Re: [PATCH] spi: davinci: Remove dead code in `davinci_spi_probe()`

[Mark Brown]

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On Mon, Apr 24, 2023 at 08:03:42PM +0800, Dongliang Mu wrote:
> On 2023/4/24 19:48, Mark Brown wrote:

> > Is that check valid?  0 was a valid interrupt for some architectures...

> We just follow the comments of platform_get_irq().

>  * Gets an IRQ for a platform device and prints an error message if finding
> the
>  * IRQ fails. Device drivers should check the return value for errors so as
> to
>  * not pass a negative integer value to the request_irq() APIs.

I'm not sure that's universally true yet, though there were some moves
to try to get us there.  arm, where this driver is used, was one of the
platforms with 0 as a valid interrupt.

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Re: [PATCH] spi: davinci: Remove dead code in `davinci_spi_probe()`

[Dongliang Mu]

On 2023/4/24 23:52, Mark Brown wrote:
> On Mon, Apr 24, 2023 at 08:03:42PM +0800, Dongliang Mu wrote:
>> On 2023/4/24 19:48, Mark Brown wrote:
>>> Is that check valid?  0 was a valid interrupt for some architectures...
>> We just follow the comments of platform_get_irq().
>>   * Gets an IRQ for a platform device and prints an error message if finding
>> the
>>   * IRQ fails. Device drivers should check the return value for errors so as
>> to
>>   * not pass a negative integer value to the request_irq() APIs.
> I'm not sure that's universally true yet, though there were some moves
> to try to get us there.  arm, where this driver is used, was one of the
> platforms with 0 as a valid interrupt.

Hi Brown,

First, we're sorry about the fact that our internal robot(beta) made a 
mistake and sent our testing message to LKML. We have fixed the 
incorrect logic.

Second, from code review of platform_get_irq / 
platform_get_irq_optional, it would warn IRQ 0 as an invalid IRQ number.

out:
	if (WARN(!ret, "0 is an invalid IRQ number\n"))
		return -EINVAL;
	return ret;

Dongliang Mu

Re: [PATCH] spi: davinci: Remove dead code in `davinci_spi_probe()`

[Mark Brown]

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On Wed, Apr 26, 2023 at 09:50:26AM +0800, Dongliang Mu wrote:

> Second, from code review of platform_get_irq / platform_get_irq_optional, it
> would warn IRQ 0 as an invalid IRQ number.

> out:
> 	if (WARN(!ret, "0 is an invalid IRQ number\n"))
> 		return -EINVAL;
> 	return ret;

Like I say I'm not sure that's actually accurate for all architectures
yet.

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Re: [PATCH] spi: davinci: Remove dead code in `davinci_spi_probe()`

[Dongliang Mu]

On 2023/4/26 22:13, Mark Brown wrote:
> On Wed, Apr 26, 2023 at 09:50:26AM +0800, Dongliang Mu wrote:
>
>> Second, from code review of platform_get_irq / platform_get_irq_optional, it
>> would warn IRQ 0 as an invalid IRQ number.
>> out:
>> 	if (WARN(!ret, "0 is an invalid IRQ number\n"))
>> 		return -EINVAL;
>> 	return ret;
> Like I say I'm not sure that's actually accurate for all architectures
> yet.

I see. Let's wait and see. When it becomes stable and universal for all 
architectures, we could clean up them all together.

Currently our team just works to make Smatch happy :)