[PATCH 3/4] backlight: lcd: call put_device if device_register fails

[PATCH 3/4] backlight: lcd: call put_device if device_register fails

[Levente Kurusa]

Currently we kfree the container of the device which failed to register.
This is wrong as the last reference is not given up with a put_device
call. Also, now that we have put_device() callen, we no longer need
the kfree as the new_ld->dev.release function will take care of kfreeing
the associated memory.

Signed-off-by: Levente Kurusa <levex@linux.com>
---
 drivers/video/backlight/lcd.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/video/backlight/lcd.c b/drivers/video/backlight/lcd.c
index 93cf15e..7de847d 100644
--- a/drivers/video/backlight/lcd.c
+++ b/drivers/video/backlight/lcd.c
@@ -228,7 +228,7 @@ struct lcd_device *lcd_device_register(const char *name, struct device *parent,
 
 	rc = device_register(&new_ld->dev);
 	if (rc) {
-		kfree(new_ld);
+		put_device(&new_ld->dev);
 		return ERR_PTR(rc);
 	}
 
-- 
1.8.3.1

Re: [PATCH 3/4] backlight: lcd: call put_device if device_register fails

[Jingoo Han]

On Saturday, December 14, 2013 3:40 AM, Levente Kurusa wrote:
> 
> Currently we kfree the container of the device which failed to register.
> This is wrong as the last reference is not given up with a put_device
> call. Also, now that we have put_device() callen, we no longer need
> the kfree as the new_ld->dev.release function will take care of kfreeing
> the associated memory.
> 
> Signed-off-by: Levente Kurusa <levex@linux.com>

(+cc Andrew Morton)

Acked-by: Jingoo Han <jg1.han@samsung.com>

It looks good.
According to the comment of device_register, put_device()
should be used, instead of directly freeing.

./drivers/base/core.c

 * NOTE: _Never_ directly free @dev after calling this function, even
 * if it returned an error! Always use put_device() to give up the
 * reference initialized in this function instead.
 */
int device_register(struct device *dev)
{
        device_initialize(dev);
        return device_add(dev);
}
EXPORT_SYMBOL_GPL(device_register);

Levente Kurusa,
By the way, don't send the same mails three times, without any
reason. It is the waste of traffic. :-(

Best regards,
Jingoo Han

> ---
>  drivers/video/backlight/lcd.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/video/backlight/lcd.c b/drivers/video/backlight/lcd.c
> index 93cf15e..7de847d 100644
> --- a/drivers/video/backlight/lcd.c
> +++ b/drivers/video/backlight/lcd.c
> @@ -228,7 +228,7 @@ struct lcd_device *lcd_device_register(const char *name, struct device *parent,
> 
>  	rc = device_register(&new_ld->dev);
>  	if (rc) {
> -		kfree(new_ld);
> +		put_device(&new_ld->dev);
>  		return ERR_PTR(rc);
>  	}
> 
> --
> 1.8.3.1

Re: [PATCH 3/4] backlight: lcd: call put_device if device_register fails

[Levente Kurusa]

On 12/16/2013 05:52 AM, Jingoo Han wrote:
> On Saturday, December 14, 2013 3:40 AM, Levente Kurusa wrote:
>>
>> Currently we kfree the container of the device which failed to register.
>> This is wrong as the last reference is not given up with a put_device
>> call. Also, now that we have put_device() callen, we no longer need
>> the kfree as the new_ld->dev.release function will take care of kfreeing
>> the associated memory.
>>
>> Signed-off-by: Levente Kurusa <levex@linux.com>
> 
> (+cc Andrew Morton)
> 
> Acked-by: Jingoo Han <jg1.han@samsung.com>
> 
> It looks good.
> According to the comment of device_register, put_device()
> should be used, instead of directly freeing.
Indeed, this is also mostly explained in [0/4]. Thanks for the Ack!
> 
[...]
> 
> Levente Kurusa,
> By the way, don't send the same mails three times, without any
> reason. It is the waste of traffic. :-(
> 

Yea, sorry about that I messed up my git's smtp config and hence most of the
messages bounced off. It didn't even reach LKML. Sorry once more.


-- 
Regards,
Levente Kurusa

Re: [PATCH 3/4] backlight: lcd: call put_device if device_register fails

[Jingoo Han]

On Saturday, December 14, 2013 3:40 AM, Levente Kurusa wrote:
> 
> Currently we kfree the container of the device which failed to register.
> This is wrong as the last reference is not given up with a put_device
> call. Also, now that we have put_device() callen, we no longer need
> the kfree as the new_ld->dev.release function will take care of kfreeing
> the associated memory.
> 
> Signed-off-by: Levente Kurusa <levex@linux.com>
> ---
>  drivers/video/backlight/lcd.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/video/backlight/lcd.c b/drivers/video/backlight/lcd.c
> index 93cf15e..7de847d 100644
> --- a/drivers/video/backlight/lcd.c
> +++ b/drivers/video/backlight/lcd.c
> @@ -228,7 +228,7 @@ struct lcd_device *lcd_device_register(const char *name, struct device *parent,
> 
>  	rc = device_register(&new_ld->dev);
>  	if (rc) {
> -		kfree(new_ld);
> +		put_device(&new_ld->dev);
>  		return ERR_PTR(rc);
>  	}

(+cc Andrew Morton)

Hi Levente Kurusa,

Would you fix the same thing for 'backlight.c' file?

./drivers/video/backlight/backlight.c
struct backlight_device *backlight_device_register(const char *name,
    .....
    rc = device_register(&new_bd->dev);
            if (rc) {
                    kfree(new_bd);
                    return ERR_PTR(rc);
            }

Best regards,
Jingoo Han