[PATCH 1/2] media: stm32-dcmi: drop unnecessary while(1) loop

[PATCH 1/2] media: stm32-dcmi: drop unnecessary while(1) loop

[Nicholas Mc Guire]

The while(1) is effectively useless as all possible paths within it
return thus there is no way to loop.

Signed-off-by: Nicholas Mc Guire <hofrat@osadl.org>
---

This is not actually fixing any bug - the while(1){ } will not hurt here
it is though simply unnecessary. Found during code review.

The diff output is not very readable - essentially only the outer
while(1){ } was removed.

Patch was compile tested with: x86_64_defconfig, MEDIA_SUPPORT=y
MEDIA_CAMERA_SUPPORT=y, V4L_PLATFORM_DRIVERS=y, OF=y, COMPILE_TEST=y
CONFIG_VIDEO_STM32_DCMI=y
(There are a number of sparse warnings - not related to the changes though)

Patch is against 4.17.0 (localversion-next is next-20180608)

 drivers/media/platform/stm32/stm32-dcmi.c | 28 +++++++++++++---------------
 1 file changed, 13 insertions(+), 15 deletions(-)

diff --git a/drivers/media/platform/stm32/stm32-dcmi.c b/drivers/media/platform/stm32/stm32-dcmi.c
index 2e1933d..70b81d2 100644
--- a/drivers/media/platform/stm32/stm32-dcmi.c
+++ b/drivers/media/platform/stm32/stm32-dcmi.c
@@ -1605,23 +1605,21 @@ static int dcmi_graph_parse(struct stm32_dcmi *dcmi, struct device_node *node)
 	struct device_node *ep = NULL;
 	struct device_node *remote;
 
-	while (1) {
-		ep = of_graph_get_next_endpoint(node, ep);
-		if (!ep)
-			return -EINVAL;
-
-		remote = of_graph_get_remote_port_parent(ep);
-		if (!remote) {
-			of_node_put(ep);
-			return -EINVAL;
-		}
+	ep = of_graph_get_next_endpoint(node, ep);
+	if (!ep)
+		return -EINVAL;
 
-		/* Remote node to connect */
-		dcmi->entity.node = remote;
-		dcmi->entity.asd.match_type = V4L2_ASYNC_MATCH_FWNODE;
-		dcmi->entity.asd.match.fwnode = of_fwnode_handle(remote);
-		return 0;
+	remote = of_graph_get_remote_port_parent(ep);
+	if (!remote) {
+		of_node_put(ep);
+		return -EINVAL;
 	}
+
+	/* Remote node to connect */
+	dcmi->entity.node = remote;
+	dcmi->entity.asd.match_type = V4L2_ASYNC_MATCH_FWNODE;
+	dcmi->entity.asd.match.fwnode = of_fwnode_handle(remote);
+	return 0;
 }
 
 static int dcmi_graph_init(struct stm32_dcmi *dcmi)
-- 
2.1.4

[PATCH 2/2] media: stm32-dcmi: add mandatory of_node_put() in success path

[Nicholas Mc Guire]

The endpoint allocated by of_graph_get_next_endpoint() needs an of_node_put()
in both error and success path. As  ep  is not used the refcount decrement
can be right after the last use of  ep.

Signed-off-by: Nicholas Mc Guire <hofrat@osadl.org>
Fixes: commit 37404f91ef8b ("[media] stm32-dcmi: STM32 DCMI camera interface driver")
---

Problem located with an experimental coccinelle script

Patch was compile tested with: x86_64_defconfig, MEDIA_SUPPORT=y
MEDIA_CAMERA_SUPPORT=y, V4L_PLATFORM_DRIVERS=y, OF=y, COMPILE_TEST=y
CONFIG_VIDEO_STM32_DCMI=y
(There are a number of sparse warnings - not related to the changes though)

Patch is on top of "[PATCH 1/2] media: stm32-dcmi: drop unneceeary while(1)
loop" against 4.17.0 (localversion-next is next-20180608)

 drivers/media/platform/stm32/stm32-dcmi.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/drivers/media/platform/stm32/stm32-dcmi.c b/drivers/media/platform/stm32/stm32-dcmi.c
index 70b81d2..542d148 100644
--- a/drivers/media/platform/stm32/stm32-dcmi.c
+++ b/drivers/media/platform/stm32/stm32-dcmi.c
@@ -1610,10 +1610,9 @@ static int dcmi_graph_parse(struct stm32_dcmi *dcmi, struct device_node *node)
 		return -EINVAL;
 
 	remote = of_graph_get_remote_port_parent(ep);
-	if (!remote) {
-		of_node_put(ep);
+	of_node_put(ep);
+	if (!remote)
 		return -EINVAL;
-	}
 
 	/* Remote node to connect */
 	dcmi->entity.node = remote;
-- 
2.1.4

[PATCH 2/2] media: stm32-dcmi: add mandatory of_node_put() in success path

[Hugues FRUCHET]

Hi Nicholas,
Thanks for patch.
BR,
Hugues.

On 06/12/2018 07:22 PM, Nicholas Mc Guire wrote:
> The endpoint allocated by of_graph_get_next_endpoint() needs an of_node_put()
> in both error and success path. As  ep  is not used the refcount decrement
> can be right after the last use of  ep.
> 
> Signed-off-by: Nicholas Mc Guire <hofrat@osadl.org>
Acked-by: Hugues Fruchet <hugues.fruchet@st.com>

> Fixes: commit 37404f91ef8b ("[media] stm32-dcmi: STM32 DCMI camera interface driver")
> ---
> 
> Problem located with an experimental coccinelle script
> 
> Patch was compile tested with: x86_64_defconfig, MEDIA_SUPPORT=y
> MEDIA_CAMERA_SUPPORT=y, V4L_PLATFORM_DRIVERS=y, OF=y, COMPILE_TEST=y
> CONFIG_VIDEO_STM32_DCMI=y
> (There are a number of sparse warnings - not related to the changes though)
> 
> Patch is on top of "[PATCH 1/2] media: stm32-dcmi: drop unneceeary while(1)
> loop" against 4.17.0 (localversion-next is next-20180608)
> 
>   drivers/media/platform/stm32/stm32-dcmi.c | 5 ++---
>   1 file changed, 2 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/media/platform/stm32/stm32-dcmi.c b/drivers/media/platform/stm32/stm32-dcmi.c
> index 70b81d2..542d148 100644
> --- a/drivers/media/platform/stm32/stm32-dcmi.c
> +++ b/drivers/media/platform/stm32/stm32-dcmi.c
> @@ -1610,10 +1610,9 @@ static int dcmi_graph_parse(struct stm32_dcmi *dcmi, struct device_node *node)
>   		return -EINVAL;
>   
>   	remote = of_graph_get_remote_port_parent(ep);
> -	if (!remote) {
> -		of_node_put(ep);
> +	of_node_put(ep);
> +	if (!remote)
>   		return -EINVAL;
> -	}
>   
>   	/* Remote node to connect */
>   	dcmi->entity.node = remote;
> 

[PATCH 1/2] media: stm32-dcmi: drop unnecessary while(1) loop

[Hugues FRUCHET]

Hi Nicholas,
thanks for patch !

On 06/12/2018 07:22 PM, Nicholas Mc Guire wrote:
> The while(1) is effectively useless as all possible paths within it
> return thus there is no way to loop.
> 
> Signed-off-by: Nicholas Mc Guire <hofrat@osadl.org>
Acked-by: Hugues Fruchet <hugues.fruchet@st.com>

> ---
> 
> This is not actually fixing any bug - the while(1){ } will not hurt here
> it is though simply unnecessary. Found during code review.
> 
> The diff output is not very readable - essentially only the outer
> while(1){ } was removed.
> 
> Patch was compile tested with: x86_64_defconfig, MEDIA_SUPPORT=y
> MEDIA_CAMERA_SUPPORT=y, V4L_PLATFORM_DRIVERS=y, OF=y, COMPILE_TEST=y
> CONFIG_VIDEO_STM32_DCMI=y
> (There are a number of sparse warnings - not related to the changes though)
> 
> Patch is against 4.17.0 (localversion-next is next-20180608)
> 
>   drivers/media/platform/stm32/stm32-dcmi.c | 28 +++++++++++++---------------
>   1 file changed, 13 insertions(+), 15 deletions(-)
> 
> diff --git a/drivers/media/platform/stm32/stm32-dcmi.c b/drivers/media/platform/stm32/stm32-dcmi.c
> index 2e1933d..70b81d2 100644
> --- a/drivers/media/platform/stm32/stm32-dcmi.c
> +++ b/drivers/media/platform/stm32/stm32-dcmi.c
> @@ -1605,23 +1605,21 @@ static int dcmi_graph_parse(struct stm32_dcmi *dcmi, struct device_node *node)
>   	struct device_node *ep = NULL;
>   	struct device_node *remote;
>   
> -	while (1) {
> -		ep = of_graph_get_next_endpoint(node, ep);
> -		if (!ep)
> -			return -EINVAL;
> -
> -		remote = of_graph_get_remote_port_parent(ep);
> -		if (!remote) {
> -			of_node_put(ep);
> -			return -EINVAL;
> -		}
> +	ep = of_graph_get_next_endpoint(node, ep);
> +	if (!ep)
> +		return -EINVAL;
>   
> -		/* Remote node to connect */
> -		dcmi->entity.node = remote;
> -		dcmi->entity.asd.match_type = V4L2_ASYNC_MATCH_FWNODE;
> -		dcmi->entity.asd.match.fwnode = of_fwnode_handle(remote);
> -		return 0;
> +	remote = of_graph_get_remote_port_parent(ep);
> +	if (!remote) {
> +		of_node_put(ep);
> +		return -EINVAL;
>   	}
> +
> +	/* Remote node to connect */
> +	dcmi->entity.node = remote;
> +	dcmi->entity.asd.match_type = V4L2_ASYNC_MATCH_FWNODE;
> +	dcmi->entity.asd.match.fwnode = of_fwnode_handle(remote);
> +	return 0;
>   }
>   
>   static int dcmi_graph_init(struct stm32_dcmi *dcmi)
> 

BR,
Hugues.