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: <d91cf14d-c7d8-1c61-9071-102f38e8c924@opensource.wdc.com>
Date:   Fri, 10 Dec 2021 07:49:38 +0900
From:   Damien Le Moal <damien.lemoal@...nsource.wdc.com>
To:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        linux-ide@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     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 2021/12/09 23:59, 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;

Otherwise, I do not think that removing the "if (!irq)" hunk is safe. no ?

> 
> Signed-off-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
> ---
>  drivers/ata/libahci_platform.c | 7 +------
>  1 file changed, 1 insertion(+), 6 deletions(-)
> 
> diff --git a/drivers/ata/libahci_platform.c b/drivers/ata/libahci_platform.c
> index 0910441321f7..1af642c84e7b 100644
> --- a/drivers/ata/libahci_platform.c
> +++ b/drivers/ata/libahci_platform.c
> @@ -579,13 +579,8 @@ int ahci_platform_init_host(struct platform_device *pdev,
>  	int i, irq, n_ports, rc;
>  
>  	irq = platform_get_irq(pdev, 0);
> -	if (irq < 0) {
> -		if (irq != -EPROBE_DEFER)
> -			dev_err(dev, "no irq\n");
> +	if (irq < 0)
>  		return irq;
> -	}
> -	if (!irq)
> -		return -EINVAL;
>  
>  	hpriv->irq = irq;
>  


-- 
Damien Le Moal
Western Digital Research