diff mbox series

[v3,01/11] leds: led-class: Add missing put_device() to led_put()

Message ID 20221216113013.126881-2-hdegoede@redhat.com (mailing list archive)
State Superseded
Headers
Series leds: lookup-table support + int3472/media privacy LED support |

Commit Message

Hans de Goede Dec. 16, 2022, 11:30 a.m. UTC 
  led_put() is used to "undo" a successful of_led_get() call,
of_led_get() uses class_find_device_by_of_node() which returns
a reference to the device which must be free-ed with put_device()
when the caller is done with it.

Add a put_device() call to led_put() to free the reference returned
by class_find_device_by_of_node().

And also add a put_device() in the error-exit case of try_module_get()
failing.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
---
 drivers/leds/led-class.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

Comments

Andy Shevchenko Dec. 16, 2022, 1:35 p.m. UTC | #1 
On Fri, Dec 16, 2022 at 12:30:03PM +0100, Hans de Goede wrote:
> led_put() is used to "undo" a successful of_led_get() call,
> of_led_get() uses class_find_device_by_of_node() which returns
> a reference to the device which must be free-ed with put_device()
> when the caller is done with it.
> 
> Add a put_device() call to led_put() to free the reference returned
> by class_find_device_by_of_node().
> 
> And also add a put_device() in the error-exit case of try_module_get()
> failing.

...

>  	led_cdev = dev_get_drvdata(led_dev);
>  
> -	if (!try_module_get(led_cdev->dev->parent->driver->owner))
> +	if (!try_module_get(led_cdev->dev->parent->driver->owner)) {
> +		put_device(led_cdev->dev);
>  		return ERR_PTR(-ENODEV);
> +	}
>  
>  	return led_cdev;

...

>  void led_put(struct led_classdev *led_cdev)
>  {
>  	module_put(led_cdev->dev->parent->driver->owner);
> +	put_device(led_cdev->dev);

Hmm... It was in the original submission.

https://lore.kernel.org/linux-leds/1443605522-1118-2-git-send-email-tomi.valkeinen@ti.com/

Nevertheless, shouldn't you put device before putting module? (It may need to
save the owner of the driver, I think.)

>  }
Andy Shevchenko Dec. 16, 2022, 1:55 p.m. UTC | #2 
On Fri, Dec 16, 2022 at 03:35:29PM +0200, Andy Shevchenko wrote:
> On Fri, Dec 16, 2022 at 12:30:03PM +0100, Hans de Goede wrote:

...

> >  	led_cdev = dev_get_drvdata(led_dev);
> >  
> > -	if (!try_module_get(led_cdev->dev->parent->driver->owner))
> > +	if (!try_module_get(led_cdev->dev->parent->driver->owner)) {
> > +		put_device(led_cdev->dev);
> >  		return ERR_PTR(-ENODEV);
> > +	}
> >  
> >  	return led_cdev;
> 
> ...
> 
> >  void led_put(struct led_classdev *led_cdev)
> >  {
> >  	module_put(led_cdev->dev->parent->driver->owner);
> > +	put_device(led_cdev->dev);
> 
> Hmm... It was in the original submission.
> 
> https://lore.kernel.org/linux-leds/1443605522-1118-2-git-send-email-tomi.valkeinen@ti.com/

...

> Nevertheless, shouldn't you put device before putting module? (It may need to
> save the owner of the driver, I think.)

I think this is wrong, the symmetry is kept correct in your patch.
Hans de Goede Dec. 16, 2022, 3:22 p.m. UTC | #3 
Hi,

On 12/16/22 14:55, Andy Shevchenko wrote:
> On Fri, Dec 16, 2022 at 03:35:29PM +0200, Andy Shevchenko wrote:
>> On Fri, Dec 16, 2022 at 12:30:03PM +0100, Hans de Goede wrote:
> 
> ...
> 
>>>  	led_cdev = dev_get_drvdata(led_dev);
>>>  
>>> -	if (!try_module_get(led_cdev->dev->parent->driver->owner))
>>> +	if (!try_module_get(led_cdev->dev->parent->driver->owner)) {
>>> +		put_device(led_cdev->dev);
>>>  		return ERR_PTR(-ENODEV);
>>> +	}
>>>  
>>>  	return led_cdev;
>>
>> ...
>>
>>>  void led_put(struct led_classdev *led_cdev)
>>>  {
>>>  	module_put(led_cdev->dev->parent->driver->owner);
>>> +	put_device(led_cdev->dev);
>>
>> Hmm... It was in the original submission.
>>
>> https://lore.kernel.org/linux-leds/1443605522-1118-2-git-send-email-tomi.valkeinen@ti.com/
> 
> ...
> 
>> Nevertheless, shouldn't you put device before putting module? (It may need to
>> save the owner of the driver, I think.)
> 
> I think this is wrong, the symmetry is kept correct in your patch.

Right, the line above dereferences led_cdev->dev, so the put()
must be done after that line.

Regards,

Hans
diff mbox series

Patch

diff --git a/drivers/leds/led-class.c b/drivers/leds/led-class.c
index 6a8ea94834fa..7391d2cf1370 100644
--- a/drivers/leds/led-class.c
+++ b/drivers/leds/led-class.c
@@ -241,8 +241,10 @@  struct led_classdev *of_led_get(struct device_node *np, int index)
 
 	led_cdev = dev_get_drvdata(led_dev);
 
-	if (!try_module_get(led_cdev->dev->parent->driver->owner))
+	if (!try_module_get(led_cdev->dev->parent->driver->owner)) {
+		put_device(led_cdev->dev);
 		return ERR_PTR(-ENODEV);
+	}
 
 	return led_cdev;
 }
@@ -255,6 +257,7 @@  EXPORT_SYMBOL_GPL(of_led_get);
 void led_put(struct led_classdev *led_cdev)
 {
 	module_put(led_cdev->dev->parent->driver->owner);
+	put_device(led_cdev->dev);
 }
 EXPORT_SYMBOL_GPL(led_put);