linux-kernel - Re: [PATCH 1/2] misc/pvpanic: Fix error handling in 'pvpanic_pci

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Message-ID: <ada55e25-5eb3-9b6b-5783-d2303db9bf83@wanadoo.fr>
Date:   Mon, 17 May 2021 12:02:24 +0200
From:   Christophe JAILLET <christophe.jaillet@...adoo.fr>
To:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc:     arnd@...db.de, gregkh@...uxfoundation.org,
        mihai.carabas@...cle.com, pizhenwei@...edance.com,
        pbonzini@...hat.com, linqiheng@...wei.com,
        linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org
Subject: Re: [PATCH 1/2] misc/pvpanic: Fix error handling in
 'pvpanic_pci_probe()'

Le 17/05/2021 à 10:01, Andy Shevchenko a écrit :
> On Sun, May 16, 2021 at 04:36:55PM +0200, Christophe JAILLET wrote:
>> There is no error handling path in the probe function.
>> Switch to managed resource so that errors in the probe are handled easily
>> and simplify the remove function accordingly.
> 
> Yes, that's what I suggested earlier to another contributor.
> 
> Reviewed-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
> 
> Thanks!
> 
> P.S. You may consider the following things as well:
>   1) converting to use pci_set_drvdata() / pci_get_drvdata()

I can send a patch for that if you want.
But it looks really low value for a driver that is already very short 
and clean.

>   2) providing devm_pvpanic_probe() [via devm_add_action() /
>      devm_add_action_or_reset()]

I don't follow you here.
The goal would be to avoid the remove function and "record" the needed 
action directly in the probe?

If this is it, I would only see an unusual pattern and a harder to 
follow logic.

Did I miss something?
What would be the benefit?

CJ

> 
>> Fixes: db3a4f0abefd ("misc/pvpanic: add PCI driver")
>> Signed-off-by: Christophe JAILLET <christophe.jaillet@...adoo.fr>
>> ---
>>   drivers/misc/pvpanic/pvpanic-pci.c | 9 +++------
>>   1 file changed, 3 insertions(+), 6 deletions(-)
>>
>> diff --git a/drivers/misc/pvpanic/pvpanic-pci.c b/drivers/misc/pvpanic/pvpanic-pci.c
>> index 9ecc4e8559d5..046ce4ecc195 100644
>> --- a/drivers/misc/pvpanic/pvpanic-pci.c
>> +++ b/drivers/misc/pvpanic/pvpanic-pci.c
>> @@ -78,15 +78,15 @@ static int pvpanic_pci_probe(struct pci_dev *pdev,
>>   	void __iomem *base;
>>   	int ret;
>>   
>> -	ret = pci_enable_device(pdev);
>> +	ret = pcim_enable_device(pdev);
>>   	if (ret < 0)
>>   		return ret;
>>   
>> -	base = pci_iomap(pdev, 0, 0);
>> +	base = pcim_iomap(pdev, 0, 0);
>>   	if (!base)
>>   		return -ENOMEM;
>>   
>> -	pi = kmalloc(sizeof(*pi), GFP_ATOMIC);
>> +	pi = devm_kmalloc(&pdev->dev, sizeof(*pi), GFP_ATOMIC);
>>   	if (!pi)
>>   		return -ENOMEM;
>>   
>> @@ -107,9 +107,6 @@ static void pvpanic_pci_remove(struct pci_dev *pdev)
>>   	struct pvpanic_instance *pi = dev_get_drvdata(&pdev->dev);
>>   
>>   	pvpanic_remove(pi);
>> -	iounmap(pi->base);
>> -	kfree(pi);
>> -	pci_disable_device(pdev);
>>   }
>>   
>>   static struct pci_driver pvpanic_pci_driver = {
>> -- 
>> 2.30.2
>>
>