Re: [PATCH v1 1/2] ata: libahci_platform: Get rid of dup message when IRQ can't be retrieved

Sergey Shtylyov
2021-12-10T11:19:58Z

On 12/10/21 1:46 PM, Andy Shevchenko wrote:

>>>> platform_get_irq() will print a message when it fails.
>>>> No need to repeat this.
>>>>
>>>> While at it, drop redundant check for 0 as platform_get_irq() spills
>>>> out a big WARN() in such case.
>>>
>>> The reason you should be able to remove the "if (!irq)" test is that
>>> platform_get_irq() never returns 0. At least, that is what the function kdoc
>>> says. But looking at platform_get_irq_optional(), which is called by
>>> platform_get_irq(), the out label is:
>>>
>>> WARN(ret == 0, "0 is an invalid IRQ number\n");
>>> return ret;
>>>
>>> So 0 will be returned as-is. That is rather weird. That should be fixed to
>>> return -ENXIO:
>>>
>>> if (WARN(ret == 0, "0 is an invalid IRQ number\n"))
>>> return -ENXIO;
>>> return ret;
>>
>> My unmerged patch (https://marc.info/?l=linux-kernel&m=163623041902285) does this
>> but returns -EINVAL instead.
>>
>>> Otherwise, I do not think that removing the "if (!irq)" hunk is safe. no ?
>>
>> Of course it isn't...
>
> It's unsubstantiated statement. The vIRQ 0 shouldn't be returned by any of
> those API calls.

We do _not_ know what needs to be fixed, that's the problem, and that's why the WARN()
is there...

> If it is the case, go and fix them, no need to workaround
> in each of the callers.

There's a need to work around as long as IRQ0 ican be returned, otherwise we get
partly functioning or non-functioning drivers...

MBR, Sergey