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

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Date:   Fri, 10 Dec 2021 22:30:51 +0300
From:   Sergey Shtylyov <s.shtylyov@....ru>
To:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
CC:     Sergei Shtylyov <sergei.shtylyov@...il.com>,
        Damien Le Moal <damien.lemoal@...nsource.wdc.com>,
        <linux-ide@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        Hans de Goede <hdegoede@...hat.com>,
        "Jens Axboe" <axboe@...nel.dk>
Subject: Re: [PATCH v1 1/2] ata: libahci_platform: Get rid of dup message when
 IRQ can't be retrieved

On 12/10/21 10:25 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...
>>>>>
>>>>> So, have you seen this warning (being reported) related to libahci_platform?
>>>>
>>>>    No (as if you need to really see this while it's obvious from the code review).
>>>>
>>>>> If no, what we are discussing about then? The workaround is redundant and
>>>>
>>>>    I don't know. :-) Your arguments so far seem bogus (sorry! :-))...
>>>
>>> It seems you haven't got them at all. The problems of platform_get_irq() et al
>>> shouldn't be worked around in the callers.
>>
>>    I have clearly explained to you what I'm working around there. If that wasn't clear
>> enough, I don't want to continue this talk anymore. Good luck with your patch (not this
>> one).
> 
> Good luck with yours, not the one that touches platform_get_irq_optional() though!

   Mmh, I'm not touching it any way that would break what your patch was trying to do,
unless you've re-thopught that. It also shoudn't matter whose patch gets merged 1st 
other than some small adaptation).

MBR, Sergey