linux-kernel - Re: [PATCH v2 05/11] pci: use helper for safer setting of driver_override

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Message-ID: <f7347531-8aa4-c011-d405-dea93e29779f@canonical.com>
Date:   Thu, 24 Feb 2022 08:49:15 +0100
From:   Krzysztof Kozlowski <krzysztof.kozlowski@...onical.com>
To:     Bjorn Helgaas <helgaas@...nel.org>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Stuart Yoder <stuyoder@...il.com>,
        Laurentiu Tudor <laurentiu.tudor@....com>,
        Abel Vesa <abel.vesa@....com>, Shawn Guo <shawnguo@...nel.org>,
        Sascha Hauer <s.hauer@...gutronix.de>,
        Fabio Estevam <festevam@...il.com>,
        "K. Y. Srinivasan" <kys@...rosoft.com>,
        Haiyang Zhang <haiyangz@...rosoft.com>,
        Stephen Hemminger <sthemmin@...rosoft.com>,
        Wei Liu <wei.liu@...nel.org>, Dexuan Cui <decui@...rosoft.com>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Mathieu Poirier <mathieu.poirier@...aro.org>,
        Vineeth Vijayan <vneethv@...ux.ibm.com>,
        Peter Oberparleiter <oberpar@...ux.ibm.com>,
        Heiko Carstens <hca@...ux.ibm.com>,
        Vasily Gorbik <gor@...ux.ibm.com>,
        Alexander Gordeev <agordeev@...ux.ibm.com>,
        Christian Borntraeger <borntraeger@...ux.ibm.com>,
        Sven Schnelle <svens@...ux.ibm.com>,
        Andy Gross <agross@...nel.org>,
        Srinivas Kandagatla <srinivas.kandagatla@...aro.org>,
        Mark Brown <broonie@...nel.org>,
        "Michael S. Tsirkin" <mst@...hat.com>,
        Jason Wang <jasowang@...hat.com>, linux-kernel@...r.kernel.org,
        linux-clk@...r.kernel.org, NXP Linux Team <linux-imx@....com>,
        linux-arm-kernel@...ts.infradead.org, linux-hyperv@...r.kernel.org,
        linux-pci@...r.kernel.org, linux-remoteproc@...r.kernel.org,
        linux-s390@...r.kernel.org, linux-arm-msm@...r.kernel.org,
        alsa-devel@...a-project.org, linux-spi@...r.kernel.org,
        virtualization@...ts.linux-foundation.org,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Rasmus Villemoes <linux@...musvillemoes.dk>
Subject: Re: [PATCH v2 05/11] pci: use helper for safer setting of
 driver_override

On 23/02/2022 22:51, Bjorn Helgaas wrote:
> In subject, to match drivers/pci/ convention, do something like:
> 
>   PCI: Use driver_set_override() instead of open-coding
> 
> On Wed, Feb 23, 2022 at 08:13:04PM +0100, Krzysztof Kozlowski wrote:
>> Use a helper for seting driver_override to reduce amount of duplicated
>> code.
> 
> s/seting/setting/
> 
>> Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@...onical.com>
>> ---
>>  drivers/pci/pci-sysfs.c | 24 ++++--------------------
>>  1 file changed, 4 insertions(+), 20 deletions(-)
>>
>> diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c
>> index 602f0fb0b007..16a163d4623e 100644
>> --- a/drivers/pci/pci-sysfs.c
>> +++ b/drivers/pci/pci-sysfs.c
>> @@ -567,31 +567,15 @@ static ssize_t driver_override_store(struct device *dev,
>>  				     const char *buf, size_t count)
>>  {
>>  	struct pci_dev *pdev = to_pci_dev(dev);
>> -	char *driver_override, *old, *cp;
>> +	int ret;
>>  
>>  	/* We need to keep extra room for a newline */
>>  	if (count >= (PAGE_SIZE - 1))
>>  		return -EINVAL;
> 
> This check makes no sense in the new function.  Michael alluded to
> this as well.

I am not sure if I got your comment properly. You mean here:
1. Move this check to driver_set_override()?
2. Remove the check entirely?

> 
>> -	driver_override = kstrndup(buf, count, GFP_KERNEL);
>> -	if (!driver_override)
>> -		return -ENOMEM;
>> -
>> -	cp = strchr(driver_override, '\n');
>> -	if (cp)
>> -		*cp = '\0';
>> -
>> -	device_lock(dev);
>> -	old = pdev->driver_override;
>> -	if (strlen(driver_override)) {
>> -		pdev->driver_override = driver_override;
>> -	} else {
>> -		kfree(driver_override);
>> -		pdev->driver_override = NULL;
>> -	}
>> -	device_unlock(dev);
>> -
>> -	kfree(old);
>> +	ret = driver_set_override(dev, &pdev->driver_override, buf);
>> +	if (ret)
>> +		return ret;
>>  
>>  	return count;
>>  }
>> -- 
>> 2.32.0
>>
>>
>> _______________________________________________
>> linux-arm-kernel mailing list
>> linux-arm-kernel@...ts.infradead.org
>> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

Best regards,
Krzysztof

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