diff mbox series

[v2,05/11] pci: use helper for safer setting of driver_override

Message ID 20220223191310.347669-6-krzysztof.kozlowski@canonical.com (mailing list archive)
State Not Applicable, archived
Headers show
Series Fix broken usage of driver_override (and kfree of static memory) | expand

Commit Message

Krzysztof Kozlowski Feb. 23, 2022, 7:13 p.m. UTC
Use a helper for seting driver_override to reduce amount of duplicated
code.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
---
 drivers/pci/pci-sysfs.c | 24 ++++--------------------
 1 file changed, 4 insertions(+), 20 deletions(-)

Comments

Bjorn Helgaas Feb. 23, 2022, 9:51 p.m. UTC | #1
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@canonical.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.

> -	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@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
Krzysztof Kozlowski Feb. 24, 2022, 7:49 a.m. UTC | #2
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@canonical.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@lists.infradead.org
>> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel


Best regards,
Krzysztof
Bjorn Helgaas Feb. 24, 2022, 11:52 p.m. UTC | #3
On Thu, Feb 24, 2022 at 08:49:15AM +0100, Krzysztof Kozlowski wrote:
> 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.
> >> @@ -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?

I was mistaken about the purpose of the comment and the check.  I
thought it had to do with *this* function, and this function doesn't
add a newline, and there's no obvious connection with PAGE_SIZE.

But looking closer, I think the "extra room for a newline" is really
to make sure that *driver_override_show()* can add a newline and have
it still fit within the PAGE_SIZE sysfs limit.

Most driver_override_*() functions have the same comment, so maybe
this was obvious to everybody except me :)  I do see that spi.c adds
"when displaying value" at the end, which helps a lot.

Sorry for the wild goose chase.

> >> -	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@lists.infradead.org
> >> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
> 
> 
> Best regards,
> Krzysztof
> 
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
Krzysztof Kozlowski Feb. 25, 2022, 9:36 a.m. UTC | #4
On 25/02/2022 00:52, Bjorn Helgaas wrote:
> On Thu, Feb 24, 2022 at 08:49:15AM +0100, Krzysztof Kozlowski wrote:
>> 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.
>>>> @@ -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?
> 
> I was mistaken about the purpose of the comment and the check.  I
> thought it had to do with *this* function, and this function doesn't
> add a newline, and there's no obvious connection with PAGE_SIZE.
> 
> But looking closer, I think the "extra room for a newline" is really
> to make sure that *driver_override_show()* can add a newline and have
> it still fit within the PAGE_SIZE sysfs limit.
> 
> Most driver_override_*() functions have the same comment, so maybe
> this was obvious to everybody except me :)  I do see that spi.c adds
> "when displaying value" at the end, which helps a lot.
> 
> Sorry for the wild goose chase.

I think I will move this check anyway to driver_set_override() helper,
because there is no particular benefit to have duplicated all over. The
helper will receive "count" argument so can perform all checks.


Best regards,
Krzysztof
Bjorn Helgaas Feb. 25, 2022, 5:13 p.m. UTC | #5
On Fri, Feb 25, 2022 at 10:36:20AM +0100, Krzysztof Kozlowski wrote:
> On 25/02/2022 00:52, Bjorn Helgaas wrote:
> > On Thu, Feb 24, 2022 at 08:49:15AM +0100, Krzysztof Kozlowski wrote:
> >> 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.
> >>>> @@ -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?
> > 
> > I was mistaken about the purpose of the comment and the check.  I
> > thought it had to do with *this* function, and this function doesn't
> > add a newline, and there's no obvious connection with PAGE_SIZE.
> > 
> > But looking closer, I think the "extra room for a newline" is really
> > to make sure that *driver_override_show()* can add a newline and have
> > it still fit within the PAGE_SIZE sysfs limit.
> > 
> > Most driver_override_*() functions have the same comment, so maybe
> > this was obvious to everybody except me :)  I do see that spi.c adds
> > "when displaying value" at the end, which helps a lot.
> > 
> > Sorry for the wild goose chase.
> 
> I think I will move this check anyway to driver_set_override() helper,
> because there is no particular benefit to have duplicated all over. The
> helper will receive "count" argument so can perform all checks.

Thanks, I think that would be good!

Bjorn
diff mbox series

Patch

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;
 
-	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;
 }