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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Message-ID: <YbOpu2whB5NaXbNa@smile.fi.intel.com>
Date:   Fri, 10 Dec 2021 21:25:47 +0200
From:   Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:     Sergey Shtylyov <s.shtylyov@....ru>
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 Fri, Dec 10, 2021 at 10:01:04PM +0300, Sergey Shtylyov wrote:
> On 12/10/21 8:59 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!

-- 
With Best Regards,
Andy Shevchenko