linux-kernel - Re: [PATCH 4/7 v2] net: ethernet: i825xx: Fix platform_get

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Message-ID: <d0b7e1cc-4190-437a-6461-35cee6edc203@cogentembedded.com>
Date:   Wed, 6 Dec 2017 15:19:24 +0300
From:   Sergei Shtylyov <sergei.shtylyov@...entembedded.com>
To:     David Miller <davem@...emloft.net>, arvind.yadav.cs@...il.com
Cc:     wg@...ndegger.com, mkl@...gutronix.de, michal.simek@...inx.com,
        opendmb@...il.com, f.fainelli@...il.com,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        netdev@...r.kernel.org
Subject: Re: [PATCH 4/7 v2] net: ethernet: i825xx: Fix platform_get_irq's
 error checking

On 12/05/2017 06:49 PM, David Miller wrote:

>>> From: Arvind Yadav <arvind.yadav.cs@...il.com>
>>> Date: Mon,  4 Dec 2017 23:18:20 +0530
>>>
>>>> @@ -120,9 +120,10 @@ static int sni_82596_probe(struct platform_device
>>>> *dev)
>>>>    	netdevice->dev_addr[5] = readb(eth_addr + 0x06);
>>>>    	iounmap(eth_addr);
>>>>    -	if (!netdevice->irq) {
>>>> +	if (netdevice->irq <= 0) {
>>>>    		printk(KERN_ERR "%s: IRQ not found for i82596 at 0x%lx\n",
>>>>    			__FILE__, netdevice->base_addr);
>>>> +		retval = netdevice->irq ? netdevice->irq : -ENODEV;
>>>>    		goto probe_failed;
>>>>    	}
>>> Ok, thinking about this some more...
>>>
>>> It is impossible to use platform_get_irq() without every single call
>>> site having this funny:
>>>
>>> 	ret = val ? val : -ENODEV;
>>>
>>> sequence.
>>>
>>> This is unnecessary duplication and it is also error prone, so I
>>> really think this logic belongs in platform_get_irq() itself.  It can
>>> convert '0' to -ENODEV and that way we need no special logic in the
>>> callers at all.
>> platform_get_irq() will return 0 only for sparc, If sparc initialize
>> platform
>> data irq[PROMINTR_MAX] as zero. Otherwise platform_get_irq() will
>> never return
>> 0. It will return either IRQ number or error (as negative number). But
>> I am getting
>> review comment by reviewer/maintainer in other subsystem to add check
>> for
>> zero. So I have done same changes here. Please correct me if i am
>> wrong.
> 
> If you make the change that I suggest, you instead can check for

    I assume such change is needed only for the SPARC-specific section of 
platform_get_irq()?

> '-ENODEV' to mean no IRQ.

    No specific error check is needed, just irq < 0 check should be enough...
Also, looking at platform_get_irq(), -ENXIO should be returned in this case.

MBR, Sergei