[PATCH 0/3] drm/mediatek: fixes for ovl_adaptor

[PATCH 0/3] drm/mediatek: fixes for ovl_adaptor

[Javier Carrasco]

The main fix is a possible memory leak on an early exit in the
for_each_child_of_node() loop. That fix has been divided into a patch
that can be backported (a simple of_node_put()), and another one that
uses the scoped variant of the macro, removing the need for any
of_node_put(). That prevents mistakes if new break/return instructions
are added, but the macro might not be available in older kernels.

When at it, an unused header has been dropped.

Signed-off-by: Javier Carrasco <javier.carrasco.cruz@gmail.com>
---
Javier Carrasco (3):
      drm/mediatek: ovl_adaptor: drop unused mtk_crtc.h header
      drm/mediatek: ovl_adaptor: add missing of_node_put()
      drm/mediatek: ovl_adaptor: use scoped variant of for_each_child_of_node()

 drivers/gpu/drm/mediatek/mtk_disp_ovl_adaptor.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)
---
base-commit: f76698bd9a8ca01d3581236082d786e9a6b72bb7
change-id: 20240624-mtk_disp_ovl_adaptor_scoped-0702a6b23443

Best regards,
-- 
Javier Carrasco <javier.carrasco.cruz@gmail.com>

[PATCH 1/3] drm/mediatek: ovl_adaptor: drop unused mtk_crtc.h header

[Javier Carrasco]

None of the elements from that header is used in this file.

Signed-off-by: Javier Carrasco <javier.carrasco.cruz@gmail.com>
---
 drivers/gpu/drm/mediatek/mtk_disp_ovl_adaptor.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/drivers/gpu/drm/mediatek/mtk_disp_ovl_adaptor.c b/drivers/gpu/drm/mediatek/mtk_disp_ovl_adaptor.c
index 02dd7dcdfedb..1418992311c4 100644
--- a/drivers/gpu/drm/mediatek/mtk_disp_ovl_adaptor.c
+++ b/drivers/gpu/drm/mediatek/mtk_disp_ovl_adaptor.c
@@ -17,7 +17,6 @@
 #include <linux/soc/mediatek/mtk-mmsys.h>
 #include <linux/soc/mediatek/mtk-mutex.h>
 
-#include "mtk_crtc.h"
 #include "mtk_ddp_comp.h"
 #include "mtk_disp_drv.h"
 #include "mtk_drm_drv.h"

-- 
2.40.1

Re: [PATCH 1/3] drm/mediatek: ovl_adaptor: drop unused mtk_crtc.h header

[CK Hu (胡俊光)]

Hi, Javier:

On Mon, 2024-06-24 at 18:43 +0200, Javier Carrasco wrote:
>  	 
> External email : Please do not click links or open attachments until you have verified the sender or the content.
>  None of the elements from that header is used in this file.

Reviewed-by: CK Hu <ck.hu@mediatek.com>

> 
> Signed-off-by: Javier Carrasco <javier.carrasco.cruz@gmail.com>
> ---
>  drivers/gpu/drm/mediatek/mtk_disp_ovl_adaptor.c | 1 -
>  1 file changed, 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/mediatek/mtk_disp_ovl_adaptor.c b/drivers/gpu/drm/mediatek/mtk_disp_ovl_adaptor.c
> index 02dd7dcdfedb..1418992311c4 100644
> --- a/drivers/gpu/drm/mediatek/mtk_disp_ovl_adaptor.c
> +++ b/drivers/gpu/drm/mediatek/mtk_disp_ovl_adaptor.c
> @@ -17,7 +17,6 @@
>  #include <linux/soc/mediatek/mtk-mmsys.h>
>  #include <linux/soc/mediatek/mtk-mutex.h>
>  
> -#include "mtk_crtc.h"
>  #include "mtk_ddp_comp.h"
>  #include "mtk_disp_drv.h"
>  #include "mtk_drm_drv.h"
> 
> -- 
> 2.40.1
> 

[PATCH 2/3] drm/mediatek: ovl_adaptor: add missing of_node_put()

[Javier Carrasco]

Error paths that exit for_each_child_of_node() need to call
of_node_put() to decerement the child refcount and avoid memory leaks.

Add the missing of_node_put().

Cc: stable@vger.kernel.org
Fixes: 453c3364632a ("drm/mediatek: Add ovl_adaptor support for MT8195")
Signed-off-by: Javier Carrasco <javier.carrasco.cruz@gmail.com>
---
 drivers/gpu/drm/mediatek/mtk_disp_ovl_adaptor.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/mediatek/mtk_disp_ovl_adaptor.c b/drivers/gpu/drm/mediatek/mtk_disp_ovl_adaptor.c
index 1418992311c4..3faf26a55e77 100644
--- a/drivers/gpu/drm/mediatek/mtk_disp_ovl_adaptor.c
+++ b/drivers/gpu/drm/mediatek/mtk_disp_ovl_adaptor.c
@@ -522,8 +522,10 @@ static int ovl_adaptor_comp_init(struct device *dev, struct component_match **ma
 		}
 
 		comp_pdev = of_find_device_by_node(node);
-		if (!comp_pdev)
+		if (!comp_pdev) {
+			of_node_put(node);
 			return -EPROBE_DEFER;
+		}
 
 		priv->ovl_adaptor_comp[id] = &comp_pdev->dev;
 

-- 
2.40.1

Re: [PATCH 2/3] drm/mediatek: ovl_adaptor: add missing of_node_put()

[CK Hu (胡俊光)]

Hi, Javier:

On Mon, 2024-06-24 at 18:43 +0200, Javier Carrasco wrote:
>  	 
> External email : Please do not click links or open attachments until you have verified the sender or the content.
>  Error paths that exit for_each_child_of_node() need to call
> of_node_put() to decerement the child refcount and avoid memory leaks.
> 
> Add the missing of_node_put().

Reviewed-by: CK Hu <ck.hu@mediatek.com>

> 
> Cc: stable@vger.kernel.org
> Fixes: 453c3364632a ("drm/mediatek: Add ovl_adaptor support for MT8195")
> Signed-off-by: Javier Carrasco <javier.carrasco.cruz@gmail.com>
> ---
>  drivers/gpu/drm/mediatek/mtk_disp_ovl_adaptor.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/mediatek/mtk_disp_ovl_adaptor.c b/drivers/gpu/drm/mediatek/mtk_disp_ovl_adaptor.c
> index 1418992311c4..3faf26a55e77 100644
> --- a/drivers/gpu/drm/mediatek/mtk_disp_ovl_adaptor.c
> +++ b/drivers/gpu/drm/mediatek/mtk_disp_ovl_adaptor.c
> @@ -522,8 +522,10 @@ static int ovl_adaptor_comp_init(struct device *dev, struct component_match **ma
>  }
>  
>  comp_pdev = of_find_device_by_node(node);
> -if (!comp_pdev)
> +if (!comp_pdev) {
> +of_node_put(node);
>  return -EPROBE_DEFER;
> +}
>  
>  priv->ovl_adaptor_comp[id] = &comp_pdev->dev;
>  
> 
> -- 
> 2.40.1
> 
> 

[PATCH 3/3] drm/mediatek: ovl_adaptor: use scoped variant of for_each_child_of_node()

[Javier Carrasco]

In order to avoid potential memory leaks if new error paths are added
without a call to of_node_put(), use for_each_child_of_node_scoped()
instead of for_each_child_of_node(). The former automatically decrements
the refcount when the child goes out of scope, which removes the need
for explicit calls to of_node_put().

Signed-off-by: Javier Carrasco <javier.carrasco.cruz@gmail.com>
---
 drivers/gpu/drm/mediatek/mtk_disp_ovl_adaptor.c | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/mediatek/mtk_disp_ovl_adaptor.c b/drivers/gpu/drm/mediatek/mtk_disp_ovl_adaptor.c
index 3faf26a55e77..aec927cce468 100644
--- a/drivers/gpu/drm/mediatek/mtk_disp_ovl_adaptor.c
+++ b/drivers/gpu/drm/mediatek/mtk_disp_ovl_adaptor.c
@@ -493,12 +493,12 @@ static int compare_of(struct device *dev, void *data)
 static int ovl_adaptor_comp_init(struct device *dev, struct component_match **match)
 {
 	struct mtk_disp_ovl_adaptor *priv = dev_get_drvdata(dev);
-	struct device_node *node, *parent;
+	struct device_node *parent;
 	struct platform_device *comp_pdev;
 
 	parent = dev->parent->parent->of_node->parent;
 
-	for_each_child_of_node(parent, node) {
+	for_each_child_of_node_scoped(parent, node) {
 		const struct of_device_id *of_id;
 		enum mtk_ovl_adaptor_comp_type type;
 		int id;
@@ -522,10 +522,8 @@ static int ovl_adaptor_comp_init(struct device *dev, struct component_match **ma
 		}
 
 		comp_pdev = of_find_device_by_node(node);
-		if (!comp_pdev) {
-			of_node_put(node);
+		if (!comp_pdev)
 			return -EPROBE_DEFER;
-		}
 
 		priv->ovl_adaptor_comp[id] = &comp_pdev->dev;
 

-- 
2.40.1

Re: [PATCH 3/3] drm/mediatek: ovl_adaptor: use scoped variant of for_each_child_of_node()

[CK Hu (胡俊光)]

Hi, Javier:

On Mon, 2024-06-24 at 18:43 +0200, Javier Carrasco wrote:
>  	 
> External email : Please do not click links or open attachments until you have verified the sender or the content.
>  In order to avoid potential memory leaks if new error paths are added
> without a call to of_node_put(), use for_each_child_of_node_scoped()
> instead of for_each_child_of_node(). The former automatically decrements
> the refcount when the child goes out of scope, which removes the need
> for explicit calls to of_node_put().

Reviewed-by: CK Hu <ck.hu@mediatek.com>

> 
> Signed-off-by: Javier Carrasco <javier.carrasco.cruz@gmail.com>
> ---
>  drivers/gpu/drm/mediatek/mtk_disp_ovl_adaptor.c | 8 +++-----
>  1 file changed, 3 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/gpu/drm/mediatek/mtk_disp_ovl_adaptor.c b/drivers/gpu/drm/mediatek/mtk_disp_ovl_adaptor.c
> index 3faf26a55e77..aec927cce468 100644
> --- a/drivers/gpu/drm/mediatek/mtk_disp_ovl_adaptor.c
> +++ b/drivers/gpu/drm/mediatek/mtk_disp_ovl_adaptor.c
> @@ -493,12 +493,12 @@ static int compare_of(struct device *dev, void *data)
>  static int ovl_adaptor_comp_init(struct device *dev, struct component_match **match)
>  {
>  struct mtk_disp_ovl_adaptor *priv = dev_get_drvdata(dev);
> -struct device_node *node, *parent;
> +struct device_node *parent;
>  struct platform_device *comp_pdev;
>  
>  parent = dev->parent->parent->of_node->parent;
>  
> -for_each_child_of_node(parent, node) {
> +for_each_child_of_node_scoped(parent, node) {
>  const struct of_device_id *of_id;
>  enum mtk_ovl_adaptor_comp_type type;
>  int id;
> @@ -522,10 +522,8 @@ static int ovl_adaptor_comp_init(struct device *dev, struct component_match **ma
>  }
>  
>  comp_pdev = of_find_device_by_node(node);
> -if (!comp_pdev) {
> -of_node_put(node);
> +if (!comp_pdev)
>  return -EPROBE_DEFER;
> -}
>  
>  priv->ovl_adaptor_comp[id] = &comp_pdev->dev;
>  
> 
> -- 
> 2.40.1
> 

Re: [PATCH 0/3] drm/mediatek: fixes for ovl_adaptor

[Chun-Kuang Hu]

Hi, Javier:

Javier Carrasco <javier.carrasco.cruz@gmail.com> 於 2024年6月25日 週二 上午12:44寫道：
>
> The main fix is a possible memory leak on an early exit in the
> for_each_child_of_node() loop. That fix has been divided into a patch
> that can be backported (a simple of_node_put()), and another one that
> uses the scoped variant of the macro, removing the need for any
> of_node_put(). That prevents mistakes if new break/return instructions
> are added, but the macro might not be available in older kernels.
>
> When at it, an unused header has been dropped.

For this series, applied to mediatek-drm-next [1], thanks.

Regards,
CK

[1] https://git.kernel.org/pub/scm/linux/kernel/git/chunkuang.hu/linux.git/log/?h=mediatek-drm-next

>
> Signed-off-by: Javier Carrasco <javier.carrasco.cruz@gmail.com>
> ---
> Javier Carrasco (3):
>       drm/mediatek: ovl_adaptor: drop unused mtk_crtc.h header
>       drm/mediatek: ovl_adaptor: add missing of_node_put()
>       drm/mediatek: ovl_adaptor: use scoped variant of for_each_child_of_node()
>
>  drivers/gpu/drm/mediatek/mtk_disp_ovl_adaptor.c | 5 ++---
>  1 file changed, 2 insertions(+), 3 deletions(-)
> ---
> base-commit: f76698bd9a8ca01d3581236082d786e9a6b72bb7
> change-id: 20240624-mtk_disp_ovl_adaptor_scoped-0702a6b23443
>
> Best regards,
> --
> Javier Carrasco <javier.carrasco.cruz@gmail.com>
>