netdev - Re: [PATCH net-next] cirrus: cs89x0: fix the return value handle and remove redundant dev_warn() for platform_get

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Date: Wed, 2 Aug 2023 08:33:23 -0500
From: Alex Elder <elder@...aro.org>
To: Simon Horman <horms@...nel.org>, Ruan Jinjie <ruanjinjie@...wei.com>
Cc: davem@...emloft.net, edumazet@...gle.com, kuba@...nel.org,
 pabeni@...hat.com, wei.fang@....com, robh@...nel.org,
 bhupesh.sharma@...aro.org, arnd@...db.de, netdev@...r.kernel.org
Subject: Re: [PATCH net-next] cirrus: cs89x0: fix the return value handle and
 remove redundant dev_warn() for platform_get_irq()

On 8/2/23 3:32 AM, Simon Horman wrote:
> + Alex Elder
> 
> On Tue, Aug 01, 2023 at 09:31:21PM +0800, Ruan Jinjie wrote:
>> There is no possible for platform_get_irq() to return 0
>> and the return value of platform_get_irq() is more sensible
>> to show the error reason.
>>
>> And there is no need to call the dev_warn() function directly to print
>> a custom message when handling an error from platform_get_irq() function as
>> it is going to display an appropriate error message in case of a failure.
>>
>> Signed-off-by: Ruan Jinjie <ruanjinjie@...wei.com>

First, I agree that the dev_warn() is unnecessary.

On the "<" versus "<=" issue is something I've commented on before.

It's true that 0 is not (or should not be) a valid IRQ number.  But
at one time a several years back I couldn't convince myself that it
100% could not happen.  I no longer remember the details, and it
might not have even been in this particular case (i.e., return
from platform_get_irq()).

I do see that a85a6c86c25be ("driver core: platform: Clarify that
IRQ 0 is invalid)" got added in 2020, and it added a WARN_ON()
in platform_get_irq_optional() before returning the IRQ number if
it's zero.  So in this case, if it *did* happen to return 0,
you'd at least get a warning.

So given that you'll get a warning on a bogus 0 IRQ number, I have
no problem with this part of the patch either.

					-Alex

Reviewed-by: Alex Elder <elder@...aro.org>

> 
> Reviewed-by: Simon Horman <horms@...nel.org>
> 
>> ---
>>   drivers/net/ethernet/cirrus/cs89x0.c | 5 ++---
>>   1 file changed, 2 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/net/ethernet/cirrus/cs89x0.c b/drivers/net/ethernet/cirrus/cs89x0.c
>> index 7c51fd9fc9be..d323c5c23521 100644
>> --- a/drivers/net/ethernet/cirrus/cs89x0.c
>> +++ b/drivers/net/ethernet/cirrus/cs89x0.c
>> @@ -1854,9 +1854,8 @@ static int __init cs89x0_platform_probe(struct platform_device *pdev)
>>   		return -ENOMEM;
>>   
>>   	dev->irq = platform_get_irq(pdev, 0);
>> -	if (dev->irq <= 0) {
>> -		dev_warn(&dev->dev, "interrupt resource missing\n");
>> -		err = -ENXIO;
>> +	if (dev->irq < 0) {
>> +		err = dev->irq;
>>   		goto free;
>>   	}
>>   
>> -- 
>> 2.34.1
>>
>>