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[PATCH] drm/logicvc: Fix device node reference leak in logicvc_drm_config_parse()

Felix Gu posted 1 patch 1 week, 2 days ago 
drivers/gpu/drm/logicvc/logicvc_drm.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
[PATCH] drm/logicvc: Fix device node reference leak in logicvc_drm_config_parse()
Posted by Felix Gu 1 week, 2 days ago 
The logicvc_drm_config_parse() function calls of_get_child_by_name() to
find the "layers" node but fails to release the reference, leading to a
device node reference leak.

Fix this by using the __free(device_node) cleanup attribute to automatic
release the reference when the variable goes out of scope.

Fixes: efeeaefe9be5 ("drm: Add support for the LogiCVC display controller")
Signed-off-by: Felix Gu <ustc.gu@gmail.com>
---
 drivers/gpu/drm/logicvc/logicvc_drm.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/logicvc/logicvc_drm.c b/drivers/gpu/drm/logicvc/logicvc_drm.c
index 204b0fee55d0..bbebf4fc7f51 100644
--- a/drivers/gpu/drm/logicvc/logicvc_drm.c
+++ b/drivers/gpu/drm/logicvc/logicvc_drm.c
@@ -92,7 +92,6 @@ static int logicvc_drm_config_parse(struct logicvc_drm *logicvc)
 	struct device *dev = drm_dev->dev;
 	struct device_node *of_node = dev->of_node;
 	struct logicvc_drm_config *config = &logicvc->config;
-	struct device_node *layers_node;
 	int ret;
 
 	logicvc_of_property_parse_bool(of_node, LOGICVC_OF_PROPERTY_DITHERING,
@@ -128,7 +127,8 @@ static int logicvc_drm_config_parse(struct logicvc_drm *logicvc)
 	if (ret)
 		return ret;
 
-	layers_node = of_get_child_by_name(of_node, "layers");
+	struct device_node *layers_node __free(device_node) =
+		of_get_child_by_name(of_node, "layers");
 	if (!layers_node) {
 		drm_err(drm_dev, "Missing non-optional layers node\n");
 		return -EINVAL;

---
base-commit: 3f24e4edcd1b8981c6b448ea2680726dedd87279
change-id: 20260129-logicvc_drm-b85bad350509

Best regards,
-- 
Felix Gu <ustc.gu@gmail.com>
Re: [PATCH] drm/logicvc: Fix device node reference leak in logicvc_drm_config_parse()
Posted by Kory Maincent 4 days, 14 hours ago 
On Fri, 30 Jan 2026 00:21:19 +0800
Felix Gu <ustc.gu@gmail.com> wrote:

> The logicvc_drm_config_parse() function calls of_get_child_by_name() to
> find the "layers" node but fails to release the reference, leading to a
> device node reference leak.
> 
> Fix this by using the __free(device_node) cleanup attribute to automatic
> release the reference when the variable goes out of scope.
> 
> Fixes: efeeaefe9be5 ("drm: Add support for the LogiCVC display controller")
> Signed-off-by: Felix Gu <ustc.gu@gmail.com>
> ---
>  drivers/gpu/drm/logicvc/logicvc_drm.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/logicvc/logicvc_drm.c
> b/drivers/gpu/drm/logicvc/logicvc_drm.c index 204b0fee55d0..bbebf4fc7f51
> 100644 --- a/drivers/gpu/drm/logicvc/logicvc_drm.c
> +++ b/drivers/gpu/drm/logicvc/logicvc_drm.c
> @@ -92,7 +92,6 @@ static int logicvc_drm_config_parse(struct logicvc_drm
> *logicvc) struct device *dev = drm_dev->dev;
>  	struct device_node *of_node = dev->of_node;
>  	struct logicvc_drm_config *config = &logicvc->config;
> -	struct device_node *layers_node;
>  	int ret;
>  
>  	logicvc_of_property_parse_bool(of_node,
> LOGICVC_OF_PROPERTY_DITHERING, @@ -128,7 +127,8 @@ static int
> logicvc_drm_config_parse(struct logicvc_drm *logicvc) if (ret)
>  		return ret;
>  
> -	layers_node = of_get_child_by_name(of_node, "layers");
> +	struct device_node *layers_node __free(device_node) =
> +		of_get_child_by_name(of_node, "layers");

We usualy don't declare variable in the middle of a function.
You should rather simply change the declaration line at the top like this:
struct device_node *layers_node __free(device_node) = NULL;

Regards,
-- 
Köry Maincent, Bootlin
Embedded Linux and kernel engineering
https://bootlin.com
Re: [PATCH] drm/logicvc: Fix device node reference leak in logicvc_drm_config_parse()
Posted by Kory Maincent 4 days, 11 hours ago 
On Tue, 3 Feb 2026 10:57:47 +0100
Kory Maincent <kory.maincent@bootlin.com> wrote:

> On Fri, 30 Jan 2026 00:21:19 +0800
> Felix Gu <ustc.gu@gmail.com> wrote:
> 
> > The logicvc_drm_config_parse() function calls of_get_child_by_name() to
> > find the "layers" node but fails to release the reference, leading to a
> > device node reference leak.
> > 
> > Fix this by using the __free(device_node) cleanup attribute to automatic
> > release the reference when the variable goes out of scope.
> > 
> > Fixes: efeeaefe9be5 ("drm: Add support for the LogiCVC display controller")
> > Signed-off-by: Felix Gu <ustc.gu@gmail.com>
> > ---
> >  drivers/gpu/drm/logicvc/logicvc_drm.c | 4 ++--
> >  1 file changed, 2 insertions(+), 2 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/logicvc/logicvc_drm.c
> > b/drivers/gpu/drm/logicvc/logicvc_drm.c index 204b0fee55d0..bbebf4fc7f51
> > 100644 --- a/drivers/gpu/drm/logicvc/logicvc_drm.c
> > +++ b/drivers/gpu/drm/logicvc/logicvc_drm.c
> > @@ -92,7 +92,6 @@ static int logicvc_drm_config_parse(struct logicvc_drm
> > *logicvc) struct device *dev = drm_dev->dev;
> >  	struct device_node *of_node = dev->of_node;
> >  	struct logicvc_drm_config *config = &logicvc->config;
> > -	struct device_node *layers_node;
> >  	int ret;
> >  
> >  	logicvc_of_property_parse_bool(of_node,
> > LOGICVC_OF_PROPERTY_DITHERING, @@ -128,7 +127,8 @@ static int
> > logicvc_drm_config_parse(struct logicvc_drm *logicvc) if (ret)
> >  		return ret;
> >  
> > -	layers_node = of_get_child_by_name(of_node, "layers");
> > +	struct device_node *layers_node __free(device_node) =
> > +		of_get_child_by_name(of_node, "layers");  
> 
> We usualy don't declare variable in the middle of a function.
> You should rather simply change the declaration line at the top like this:
> struct device_node *layers_node __free(device_node) = NULL;

It seems Linus disagree on this topic and I understand his arguments:
https://lore.kernel.org/all/CAHk-=whPZoi03ZwphxiW6cuWPtC3nyKYS8_BThgztCdgPWP1WA@mail.gmail.com/
https://lore.kernel.org/all/CAHk-=wiCOTW5UftUrAnvJkr6769D29tF7Of79gUjdQHS_TkF5A@mail.gmail.com/

Then, ok to me:
Reviewed-by: Kory Maincent <kory.maincent@bootlin.com>

Thank you!
-- 
Köry Maincent, Bootlin
Embedded Linux and kernel engineering
https://bootlin.com
Re: [PATCH] drm/logicvc: Fix device node reference leak in logicvc_drm_config_parse()
Posted by Luca Ceresoli 4 days, 6 hours ago 
On Tue Feb 3, 2026 at 2:35 PM CET, Kory Maincent wrote:
> On Tue, 3 Feb 2026 10:57:47 +0100
> Kory Maincent <kory.maincent@bootlin.com> wrote:
>
>> On Fri, 30 Jan 2026 00:21:19 +0800
>> Felix Gu <ustc.gu@gmail.com> wrote:
>>
>> > The logicvc_drm_config_parse() function calls of_get_child_by_name() to
>> > find the "layers" node but fails to release the reference, leading to a
>> > device node reference leak.
>> >
>> > Fix this by using the __free(device_node) cleanup attribute to automatic
>> > release the reference when the variable goes out of scope.
>> >
>> > Fixes: efeeaefe9be5 ("drm: Add support for the LogiCVC display controller")
>> > Signed-off-by: Felix Gu <ustc.gu@gmail.com>
>> > ---
>> >  drivers/gpu/drm/logicvc/logicvc_drm.c | 4 ++--
>> >  1 file changed, 2 insertions(+), 2 deletions(-)
>> >
>> > diff --git a/drivers/gpu/drm/logicvc/logicvc_drm.c
>> > b/drivers/gpu/drm/logicvc/logicvc_drm.c index 204b0fee55d0..bbebf4fc7f51
>> > 100644 --- a/drivers/gpu/drm/logicvc/logicvc_drm.c
>> > +++ b/drivers/gpu/drm/logicvc/logicvc_drm.c
>> > @@ -92,7 +92,6 @@ static int logicvc_drm_config_parse(struct logicvc_drm
>> > *logicvc) struct device *dev = drm_dev->dev;
>> >  	struct device_node *of_node = dev->of_node;
>> >  	struct logicvc_drm_config *config = &logicvc->config;
>> > -	struct device_node *layers_node;
>> >  	int ret;
>> >
>> >  	logicvc_of_property_parse_bool(of_node,
>> > LOGICVC_OF_PROPERTY_DITHERING, @@ -128,7 +127,8 @@ static int
>> > logicvc_drm_config_parse(struct logicvc_drm *logicvc) if (ret)
>> >  		return ret;
>> >
>> > -	layers_node = of_get_child_by_name(of_node, "layers");
>> > +	struct device_node *layers_node __free(device_node) =
>> > +		of_get_child_by_name(of_node, "layers");
>>
>> We usualy don't declare variable in the middle of a function.
>> You should rather simply change the declaration line at the top like this:
>> struct device_node *layers_node __free(device_node) = NULL;
>
> It seems Linus disagree on this topic and I understand his arguments:
> https://lore.kernel.org/all/CAHk-=whPZoi03ZwphxiW6cuWPtC3nyKYS8_BThgztCdgPWP1WA@mail.gmail.com/
> https://lore.kernel.org/all/CAHk-=wiCOTW5UftUrAnvJkr6769D29tF7Of79gUjdQHS_TkF5A@mail.gmail.com/

I agree it makes code much more readable, espacially in the case of cleanup
actions.

> Then, ok to me:
> Reviewed-by: Kory Maincent <kory.maincent@bootlin.com>

Thanks! I'm applying this patch to drm-misc-fixes perhaps next week.

Luca

--
Luca Ceresoli, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com
Re: [PATCH] drm/logicvc: Fix device node reference leak in logicvc_drm_config_parse()
Posted by Luca Ceresoli 1 week, 2 days ago 
On Thu Jan 29, 2026 at 5:21 PM CET, Felix Gu wrote:
> The logicvc_drm_config_parse() function calls of_get_child_by_name() to
> find the "layers" node but fails to release the reference, leading to a
> device node reference leak.
>
> Fix this by using the __free(device_node) cleanup attribute to automatic
> release the reference when the variable goes out of scope.
>
> Fixes: efeeaefe9be5 ("drm: Add support for the LogiCVC display controller")
> Signed-off-by: Felix Gu <ustc.gu@gmail.com>

Reviewed-by: Luca Ceresoli <luca.ceresoli@bootlin.com>

--
Luca Ceresoli, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com

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