[PATCH v4 0/1] Fixes 30e2ae943c26 "drm/bridge: Introduce LT8912B DSI to HDMI"

[PATCH v4 0/1] Fixes 30e2ae943c26 "drm/bridge: Introduce LT8912B DSI to HDMI"

[Adrien Grassein]

Hi,

This patch fixes issues found by a static checker.

Thanks,

Adrien Grassein (1):
  drm/bridge: lt8912b: Fix issues found during static analysis

 drivers/gpu/drm/bridge/lontium-lt8912b.c | 27 +++++++++++++++---------
 1 file changed, 17 insertions(+), 10 deletions(-)

-- 
2.25.1

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[PATCH v4 1/1] drm/bridge: lt8912b: Fix issues found during static analysis

[Adrien Grassein]

Some issues where found during static analysis of this driver.

Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Suggested-by: Dan Carpenter  <dan.carpenter@oracle.com>
Signed-off-by: Adrien Grassein <adrien.grassein@gmail.com>
---
 drivers/gpu/drm/bridge/lontium-lt8912b.c | 27 +++++++++++++++---------
 1 file changed, 17 insertions(+), 10 deletions(-)

diff --git a/drivers/gpu/drm/bridge/lontium-lt8912b.c b/drivers/gpu/drm/bridge/lontium-lt8912b.c
index 61491615bad0..4c8d79142262 100644
--- a/drivers/gpu/drm/bridge/lontium-lt8912b.c
+++ b/drivers/gpu/drm/bridge/lontium-lt8912b.c
@@ -621,7 +621,8 @@ static int lt8912_parse_dt(struct lt8912 *lt)
 {
 	struct gpio_desc *gp_reset;
 	struct device *dev = lt->dev;
-	int ret = 0;
+	int ret;
+	int data_lanes;
 	struct device_node *port_node;
 	struct device_node *endpoint;
 
@@ -635,13 +636,16 @@ static int lt8912_parse_dt(struct lt8912 *lt)
 	lt->gp_reset = gp_reset;
 
 	endpoint = of_graph_get_endpoint_by_regs(dev->of_node, 0, -1);
-	if (IS_ERR(endpoint)) {
-		ret = PTR_ERR(endpoint);
-		goto end;
-	}
+	if (!endpoint)
+		return -ENODEV;
 
-	lt->data_lanes = of_property_count_u32_elems(endpoint, "data-lanes");
+	data_lanes = of_property_count_u32_elems(endpoint, "data-lanes");
 	of_node_put(endpoint);
+	if (data_lanes < 0) {
+		dev_err(lt->dev, "%s: Bad data-lanes property\n", __func__);
+		return data_lanes;
+	}
+	lt->data_lanes = data_lanes;
 
 	lt->host_node = of_graph_get_remote_node(dev->of_node, 0, -1);
 	if (!lt->host_node) {
@@ -658,19 +662,22 @@ static int lt8912_parse_dt(struct lt8912 *lt)
 	}
 
 	lt->hdmi_port = of_drm_find_bridge(port_node);
-	if (IS_ERR(lt->hdmi_port)) {
+	if (!lt->hdmi_port) {
 		dev_err(lt->dev, "%s: Failed to get hdmi port\n", __func__);
-		ret = PTR_ERR(lt->hdmi_port);
-		of_node_put(lt->host_node);
-		goto end;
+		ret = -ENODEV;
+		of_node_put(port_node);
+		goto err_free_host_node;
 	}
 
 	if (!of_device_is_compatible(port_node, "hdmi-connector")) {
 		dev_err(lt->dev, "%s: Failed to get hdmi port\n", __func__);
+		of_node_put(port_node);
 		ret = -EINVAL;
+		goto err_free_host_node;
 	}
 
 	of_node_put(port_node);
+	return 0;
 
 end:
 	return ret;
-- 
2.25.1

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Re: [PATCH v4 1/1] drm/bridge: lt8912b: Fix issues found during static analysis

[Dan Carpenter]

Thanks!

regards,
dan carpenter

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Re: [PATCH v4 1/1] drm/bridge: lt8912b: Fix issues found during static analysis

[Andrzej Hajda]

W dniu 31.03.2021 o 13:49, Adrien Grassein pisze:
> Some issues where found during static analysis of this driver.


Subject should describe what has been fixed, description why. If there 
is multiple different issues maybe patch split would be better.


>
> Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
> Suggested-by: Dan Carpenter  <dan.carpenter@oracle.com>
> Signed-off-by: Adrien Grassein <adrien.grassein@gmail.com>
> ---
>   drivers/gpu/drm/bridge/lontium-lt8912b.c | 27 +++++++++++++++---------
>   1 file changed, 17 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/gpu/drm/bridge/lontium-lt8912b.c b/drivers/gpu/drm/bridge/lontium-lt8912b.c
> index 61491615bad0..4c8d79142262 100644
> --- a/drivers/gpu/drm/bridge/lontium-lt8912b.c
> +++ b/drivers/gpu/drm/bridge/lontium-lt8912b.c
> @@ -621,7 +621,8 @@ static int lt8912_parse_dt(struct lt8912 *lt)
>   {
>   	struct gpio_desc *gp_reset;
>   	struct device *dev = lt->dev;
> -	int ret = 0;
> +	int ret;
> +	int data_lanes;
>   	struct device_node *port_node;
>   	struct device_node *endpoint;
>   
> @@ -635,13 +636,16 @@ static int lt8912_parse_dt(struct lt8912 *lt)
>   	lt->gp_reset = gp_reset;
>   
>   	endpoint = of_graph_get_endpoint_by_regs(dev->of_node, 0, -1);
> -	if (IS_ERR(endpoint)) {
> -		ret = PTR_ERR(endpoint);
> -		goto end;
> -	}
> +	if (!endpoint)
> +		return -ENODEV;
>   
> -	lt->data_lanes = of_property_count_u32_elems(endpoint, "data-lanes");
> +	data_lanes = of_property_count_u32_elems(endpoint, "data-lanes");
>   	of_node_put(endpoint);
> +	if (data_lanes < 0) {
> +		dev_err(lt->dev, "%s: Bad data-lanes property\n", __func__);
> +		return data_lanes;
> +	}
> +	lt->data_lanes = data_lanes;
>   
>   	lt->host_node = of_graph_get_remote_node(dev->of_node, 0, -1);
>   	if (!lt->host_node) {
> @@ -658,19 +662,22 @@ static int lt8912_parse_dt(struct lt8912 *lt)
>   	}
>   
>   	lt->hdmi_port = of_drm_find_bridge(port_node);
> -	if (IS_ERR(lt->hdmi_port)) {
> +	if (!lt->hdmi_port) {
>   		dev_err(lt->dev, "%s: Failed to get hdmi port\n", __func__);
> -		ret = PTR_ERR(lt->hdmi_port);
> -		of_node_put(lt->host_node);
> -		goto end;
> +		ret = -ENODEV;
> +		of_node_put(port_node);
> +		goto err_free_host_node;
>   	}
>   
>   	if (!of_device_is_compatible(port_node, "hdmi-connector")) {
>   		dev_err(lt->dev, "%s: Failed to get hdmi port\n", __func__);
> +		of_node_put(port_node);
>   		ret = -EINVAL;
> +		goto err_free_host_node;

Maybe better would be to put of_node_put(port_node) after 
err_free_host_node label - of_node_put(NULL) does nothing.

>   	}
>   
>   	of_node_put(port_node);
> +	return 0;
>   
>   end:
>   	return ret;

This label and code can be removed, am I right?

After reading the body I know what the patch does, so I can propose the 
subject, what about "fix incorrect handling of of_* return values".

And please make description more descriptive :)

With that fixed you can add my:

Reviewed-by: Andrzej Hajda <a.hajda@samsung.com>

Regards
Andrzej


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Re: [PATCH v4 1/1] drm/bridge: lt8912b: Fix issues found during static analysis

[Dan Carpenter]

On Wed, Mar 31, 2021 at 02:57:31PM +0200, Andrzej Hajda wrote:
> >   
> >   	if (!of_device_is_compatible(port_node, "hdmi-connector")) {
> >   		dev_err(lt->dev, "%s: Failed to get hdmi port\n", __func__);
> > +		of_node_put(port_node);
> >   		ret = -EINVAL;
> > +		goto err_free_host_node;
> 
> Maybe better would be to put of_node_put(port_node) after 
> err_free_host_node label - of_node_put(NULL) does nothing.
> 

I prefer this style for several reasons:
1) I kind of hate no-op puts
2) The port_node is not part of the wind up in the sense that we don't
   leave hold the reference on the success path.  It's the same with
   locking, I prefer if unlock happens before the goto.  Sometimes
   people do an unlock as part of the unwind but this style only works
   for the first label in the unwind path.
3) I like when you can copy and paste the unwind code to create the
   release function, lt8912_put_dt() in this example.  Normally you have
   to add one more release function because most times the last failure
   path is an allocation but in this case the release is just
   of_node_put(lt->host_node);

But, yeah, putting the of_node_put() after the label isn't bug so
whatever...

regards,
dan carpenter

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