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 12:46:28 +0200
From:   Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:     Sergey Shtylyov <s.shtylyov@....ru>
Cc:     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 11:59:00AM +0300, Sergey Shtylyov wrote:
> On 12/10/21 1:49 AM, Damien Le Moal 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. If it is the case, go and fix them, no need to workaround
in each of the callers.

-- 
With Best Regards,
Andy Shevchenko