[PATCH] drm/msm/mdp4: Fix refcount leak in mdp4_modeset_init_intf

[PATCH] drm/msm/mdp4: Fix refcount leak in mdp4_modeset_init_intf

[Miaoqian Lin]

of_graph_get_remote_node() returns remote device node pointer with
refcount incremented, we should use of_node_put() on it
when not need anymore.
Add missing of_node_put() to avoid refcount leak.

Fixes: 86418f90a4c1 ("drm: convert drivers to use of_graph_get_remote_node")
Signed-off-by: Miaoqian Lin <linmq006@gmail.com>
---
 drivers/gpu/drm/msm/disp/mdp4/mdp4_kms.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/gpu/drm/msm/disp/mdp4/mdp4_kms.c b/drivers/gpu/drm/msm/disp/mdp4/mdp4_kms.c
index fb48c8c19ec3..17cb1fc78379 100644
--- a/drivers/gpu/drm/msm/disp/mdp4/mdp4_kms.c
+++ b/drivers/gpu/drm/msm/disp/mdp4/mdp4_kms.c
@@ -216,6 +216,7 @@ static int mdp4_modeset_init_intf(struct mdp4_kms *mdp4_kms,
 		encoder = mdp4_lcdc_encoder_init(dev, panel_node);
 		if (IS_ERR(encoder)) {
 			DRM_DEV_ERROR(dev->dev, "failed to construct LCDC encoder\n");
+			of_node_put(panel_node);
 			return PTR_ERR(encoder);
 		}
 
@@ -225,6 +226,7 @@ static int mdp4_modeset_init_intf(struct mdp4_kms *mdp4_kms,
 		connector = mdp4_lvds_connector_init(dev, panel_node, encoder);
 		if (IS_ERR(connector)) {
 			DRM_DEV_ERROR(dev->dev, "failed to initialize LVDS connector\n");
+			of_node_put(panel_node);
 			return PTR_ERR(connector);
 		}
 
-- 
2.25.1

Re: [PATCH] drm/msm/mdp4: Fix refcount leak in mdp4_modeset_init_intf

[Dmitry Baryshkov]

On Tue, 7 Jun 2022 at 14:08, Miaoqian Lin <linmq006@gmail.com> wrote:
>
> of_graph_get_remote_node() returns remote device node pointer with
> refcount incremented, we should use of_node_put() on it
> when not need anymore.
> Add missing of_node_put() to avoid refcount leak.
>
> Fixes: 86418f90a4c1 ("drm: convert drivers to use of_graph_get_remote_node")
> Signed-off-by: Miaoqian Lin <linmq006@gmail.com>

Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>



-- 
With best wishes
Dmitry

Re: [PATCH] drm/msm/mdp4: Fix refcount leak in mdp4_modeset_init_intf

[Stephen Boyd]

Quoting Miaoqian Lin (2022-06-07 04:08:38)
> of_graph_get_remote_node() returns remote device node pointer with
> refcount incremented, we should use of_node_put() on it
> when not need anymore.
> Add missing of_node_put() to avoid refcount leak.
>
> Fixes: 86418f90a4c1 ("drm: convert drivers to use of_graph_get_remote_node")
> Signed-off-by: Miaoqian Lin <linmq006@gmail.com>
> ---

Reviewed-by: Stephen Boyd <swboyd@chromium.org>

Re: [PATCH] drm/msm/mdp4: Fix refcount leak in mdp4_modeset_init_intf

[Abhinav Kumar]

On 6/7/2022 4:08 AM, Miaoqian Lin wrote:
> of_graph_get_remote_node() returns remote device node pointer with
> refcount incremented, we should use of_node_put() on it
> when not need anymore.
> Add missing of_node_put() to avoid refcount leak.
> 
> Fixes: 86418f90a4c1 ("drm: convert drivers to use of_graph_get_remote_node")
> Signed-off-by: Miaoqian Lin <linmq006@gmail.com>
> ---
>   drivers/gpu/drm/msm/disp/mdp4/mdp4_kms.c | 2 ++
>   1 file changed, 2 insertions(+)
> 

This patch itself looks fine and will cover the cases when there was an 
error and we did not release the refcount.

But, even in the normal cases I am not finding where we are releasing 
the refcount for the panel_node.

I dont see a of_node_put() on mdp4_lcdc_encoder->panel_node.

Am i missing something?

> diff --git a/drivers/gpu/drm/msm/disp/mdp4/mdp4_kms.c b/drivers/gpu/drm/msm/disp/mdp4/mdp4_kms.c
> index fb48c8c19ec3..17cb1fc78379 100644
> --- a/drivers/gpu/drm/msm/disp/mdp4/mdp4_kms.c
> +++ b/drivers/gpu/drm/msm/disp/mdp4/mdp4_kms.c
> @@ -216,6 +216,7 @@ static int mdp4_modeset_init_intf(struct mdp4_kms *mdp4_kms,
>   		encoder = mdp4_lcdc_encoder_init(dev, panel_node);
>   		if (IS_ERR(encoder)) {
>   			DRM_DEV_ERROR(dev->dev, "failed to construct LCDC encoder\n");
> +			of_node_put(panel_node);
>   			return PTR_ERR(encoder);
>   		}
>   
> @@ -225,6 +226,7 @@ static int mdp4_modeset_init_intf(struct mdp4_kms *mdp4_kms,
>   		connector = mdp4_lvds_connector_init(dev, panel_node, encoder);
>   		if (IS_ERR(connector)) {
>   			DRM_DEV_ERROR(dev->dev, "failed to initialize LVDS connector\n");
> +			of_node_put(panel_node);
>   			return PTR_ERR(connector);
>   		}
>   

Re: [PATCH] drm/msm/mdp4: Fix refcount leak in mdp4_modeset_init_intf

[Miaoqian Lin]

Hi, Abhinav

On 2022/6/11 7:20, Abhinav Kumar wrote:
>
>
> On 6/7/2022 4:08 AM, Miaoqian Lin wrote:
>> of_graph_get_remote_node() returns remote device node pointer with
>> refcount incremented, we should use of_node_put() on it
>> when not need anymore.
>> Add missing of_node_put() to avoid refcount leak.
>>
>> Fixes: 86418f90a4c1 ("drm: convert drivers to use of_graph_get_remote_node")
>> Signed-off-by: Miaoqian Lin <linmq006@gmail.com>
>> ---
>>   drivers/gpu/drm/msm/disp/mdp4/mdp4_kms.c | 2 ++
>>   1 file changed, 2 insertions(+)
>>
>
> This patch itself looks fine and will cover the cases when there was an error and we did not release the refcount.
>
> But, even in the normal cases I am not finding where we are releasing the refcount for the panel_node.
>
> I dont see a of_node_put() on mdp4_lcdc_encoder->panel_node.
>
Thanks for your review.

I don't see it either. It's a bit messy because the reference assigned to mdp4_lcdc_encoder->panel_node and mdp4_lvds_connector->panel_node both.

> Am i missing something?
>
>> diff --git a/drivers/gpu/drm/msm/disp/mdp4/mdp4_kms.c b/drivers/gpu/drm/msm/disp/mdp4/mdp4_kms.c
>> index fb48c8c19ec3..17cb1fc78379 100644
>> --- a/drivers/gpu/drm/msm/disp/mdp4/mdp4_kms.c
>> +++ b/drivers/gpu/drm/msm/disp/mdp4/mdp4_kms.c
>> @@ -216,6 +216,7 @@ static int mdp4_modeset_init_intf(struct mdp4_kms *mdp4_kms,
>>           encoder = mdp4_lcdc_encoder_init(dev, panel_node);
>>           if (IS_ERR(encoder)) {
>>               DRM_DEV_ERROR(dev->dev, "failed to construct LCDC encoder\n");
>> +            of_node_put(panel_node);
>>               return PTR_ERR(encoder);
>>           }
>>   @@ -225,6 +226,7 @@ static int mdp4_modeset_init_intf(struct mdp4_kms *mdp4_kms,
>>           connector = mdp4_lvds_connector_init(dev, panel_node, encoder);
>>           if (IS_ERR(connector)) {
>>               DRM_DEV_ERROR(dev->dev, "failed to initialize LVDS connector\n");
>> +            of_node_put(panel_node);
>>               return PTR_ERR(connector);
>>           }
>>   

Re: [PATCH] drm/msm/mdp4: Fix refcount leak in mdp4_modeset_init_intf

[Dmitry Baryshkov]

On 14/06/2022 13:07, Miaoqian Lin wrote:
> Hi, Abhinav
> 
> On 2022/6/11 7:20, Abhinav Kumar wrote:
>>
>>
>> On 6/7/2022 4:08 AM, Miaoqian Lin wrote:
>>> of_graph_get_remote_node() returns remote device node pointer with
>>> refcount incremented, we should use of_node_put() on it
>>> when not need anymore.
>>> Add missing of_node_put() to avoid refcount leak.
>>>
>>> Fixes: 86418f90a4c1 ("drm: convert drivers to use of_graph_get_remote_node")
>>> Signed-off-by: Miaoqian Lin <linmq006@gmail.com>
>>> ---
>>>    drivers/gpu/drm/msm/disp/mdp4/mdp4_kms.c | 2 ++
>>>    1 file changed, 2 insertions(+)
>>>
>>
>> This patch itself looks fine and will cover the cases when there was an error and we did not release the refcount.
>>
>> But, even in the normal cases I am not finding where we are releasing the refcount for the panel_node.
>>
>> I dont see a of_node_put() on mdp4_lcdc_encoder->panel_node.
>>
> Thanks for your review.
> 
> I don't see it either. It's a bit messy because the reference assigned to mdp4_lcdc_encoder->panel_node and mdp4_lvds_connector->panel_node both.

I have a plan to rework mdp4 lcdc support once I get my ifc6410 lvds 
cable. Thus I think we can land this patch now and fix the mdp4 
lcdc/lvds code leaking the reference in the due time.

> 
>> Am i missing something?
>>
>>> diff --git a/drivers/gpu/drm/msm/disp/mdp4/mdp4_kms.c b/drivers/gpu/drm/msm/disp/mdp4/mdp4_kms.c
>>> index fb48c8c19ec3..17cb1fc78379 100644
>>> --- a/drivers/gpu/drm/msm/disp/mdp4/mdp4_kms.c
>>> +++ b/drivers/gpu/drm/msm/disp/mdp4/mdp4_kms.c
>>> @@ -216,6 +216,7 @@ static int mdp4_modeset_init_intf(struct mdp4_kms *mdp4_kms,
>>>            encoder = mdp4_lcdc_encoder_init(dev, panel_node);
>>>            if (IS_ERR(encoder)) {
>>>                DRM_DEV_ERROR(dev->dev, "failed to construct LCDC encoder\n");
>>> +            of_node_put(panel_node);
>>>                return PTR_ERR(encoder);
>>>            }
>>>    @@ -225,6 +226,7 @@ static int mdp4_modeset_init_intf(struct mdp4_kms *mdp4_kms,
>>>            connector = mdp4_lvds_connector_init(dev, panel_node, encoder);
>>>            if (IS_ERR(connector)) {
>>>                DRM_DEV_ERROR(dev->dev, "failed to initialize LVDS connector\n");
>>> +            of_node_put(panel_node);
>>>                return PTR_ERR(connector);
>>>            }
>>>    


-- 
With best wishes
Dmitry

Re: [PATCH] drm/msm/mdp4: Fix refcount leak in mdp4_modeset_init_intf

[Abhinav Kumar]

On 6/14/2022 3:09 AM, Dmitry Baryshkov wrote:
> On 14/06/2022 13:07, Miaoqian Lin wrote:
>> Hi, Abhinav
>>
>> On 2022/6/11 7:20, Abhinav Kumar wrote:
>>>
>>>
>>> On 6/7/2022 4:08 AM, Miaoqian Lin wrote:
>>>> of_graph_get_remote_node() returns remote device node pointer with
>>>> refcount incremented, we should use of_node_put() on it
>>>> when not need anymore.
>>>> Add missing of_node_put() to avoid refcount leak.
>>>>
>>>> Fixes: 86418f90a4c1 ("drm: convert drivers to use 
>>>> of_graph_get_remote_node")
>>>> Signed-off-by: Miaoqian Lin <linmq006@gmail.com>
>>>> ---
>>>>    drivers/gpu/drm/msm/disp/mdp4/mdp4_kms.c | 2 ++
>>>>    1 file changed, 2 insertions(+)
>>>>
>>>
>>> This patch itself looks fine and will cover the cases when there was 
>>> an error and we did not release the refcount.
>>>
>>> But, even in the normal cases I am not finding where we are releasing 
>>> the refcount for the panel_node.
>>>
>>> I dont see a of_node_put() on mdp4_lcdc_encoder->panel_node.
>>>
>> Thanks for your review.
>>
>> I don't see it either. It's a bit messy because the reference assigned 
>> to mdp4_lcdc_encoder->panel_node and mdp4_lvds_connector->panel_node 
>> both.
> 
> I have a plan to rework mdp4 lcdc support once I get my ifc6410 lvds 
> cable. Thus I think we can land this patch now and fix the mdp4 
> lcdc/lvds code leaking the reference in the due time.
> 

Alright, with that assurance,

Reviewed-by: Abhinav Kumar <quic_abhinavk@quicinc.com>

Will pick it up for -fixes.
>>
>>> Am i missing something?
>>>
>>>> diff --git a/drivers/gpu/drm/msm/disp/mdp4/mdp4_kms.c 
>>>> b/drivers/gpu/drm/msm/disp/mdp4/mdp4_kms.c
>>>> index fb48c8c19ec3..17cb1fc78379 100644
>>>> --- a/drivers/gpu/drm/msm/disp/mdp4/mdp4_kms.c
>>>> +++ b/drivers/gpu/drm/msm/disp/mdp4/mdp4_kms.c
>>>> @@ -216,6 +216,7 @@ static int mdp4_modeset_init_intf(struct 
>>>> mdp4_kms *mdp4_kms,
>>>>            encoder = mdp4_lcdc_encoder_init(dev, panel_node);
>>>>            if (IS_ERR(encoder)) {
>>>>                DRM_DEV_ERROR(dev->dev, "failed to construct LCDC 
>>>> encoder\n");
>>>> +            of_node_put(panel_node);
>>>>                return PTR_ERR(encoder);
>>>>            }
>>>>    @@ -225,6 +226,7 @@ static int mdp4_modeset_init_intf(struct 
>>>> mdp4_kms *mdp4_kms,
>>>>            connector = mdp4_lvds_connector_init(dev, panel_node, 
>>>> encoder);
>>>>            if (IS_ERR(connector)) {
>>>>                DRM_DEV_ERROR(dev->dev, "failed to initialize LVDS 
>>>> connector\n");
>>>> +            of_node_put(panel_node);
>>>>                return PTR_ERR(connector);
>>>>            }
> 
>