diff mbox series

fpga: bridge: properly initialize bridge device before populating children

Message ID 20230404133102.2837535-2-alexis.lothore@bootlin.com
State New
Headers
Series warning on FPGA bridge registration |

Commit Message

Alexis Lothoré April 4, 2023, 1:31 p.m. UTC 
  From: Alexis Lothoré <alexis.lothore@bootlin.com>

The current code path can lead to warnings because of uninitialized device,
which contains, as a consequence, uninitialized kobject. The uninitialized
device is passed to of_platform_populate, which will at some point, while
creating child device, try to get a reference on uninitialized parent,
resulting in the following warning:

kobject: '(null)' ((ptrval)): is not initialized, yet kobject_get() is
being called.

The warning is observed after migrating a kernel 5.10.x to 6.1.x.
Reverting commit 0d70af3c2530 ("fpga: bridge: Use standard dev_release for
class driver") seems to remove the warning.
This commit aggregates device_initialize() and device_add() into
device_register() but this new call is done AFTER of_platform_populate

Fixes: 0d70af3c2530 ("fpga: bridge: Use standard dev_release for class driver")
Signed-off-by: Alexis Lothoré <alexis.lothore@bootlin.com>
---
 drivers/fpga/fpga-bridge.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

Comments

Xu Yilun April 6, 2023, 4:04 p.m. UTC | #1 
On 2023-04-04 at 15:31:02 +0200, alexis.lothore@bootlin.com wrote:
> From: Alexis Lothoré <alexis.lothore@bootlin.com>
> 
> The current code path can lead to warnings because of uninitialized device,
> which contains, as a consequence, uninitialized kobject. The uninitialized
> device is passed to of_platform_populate, which will at some point, while
> creating child device, try to get a reference on uninitialized parent,
> resulting in the following warning:
> 
> kobject: '(null)' ((ptrval)): is not initialized, yet kobject_get() is
> being called.
> 
> The warning is observed after migrating a kernel 5.10.x to 6.1.x.
> Reverting commit 0d70af3c2530 ("fpga: bridge: Use standard dev_release for
> class driver") seems to remove the warning.
> This commit aggregates device_initialize() and device_add() into
> device_register() but this new call is done AFTER of_platform_populate
> 
> Fixes: 0d70af3c2530 ("fpga: bridge: Use standard dev_release for class driver")
> Signed-off-by: Alexis Lothoré <alexis.lothore@bootlin.com>
> ---
>  drivers/fpga/fpga-bridge.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/fpga/fpga-bridge.c b/drivers/fpga/fpga-bridge.c
> index 727704431f61..13918c8c839e 100644
> --- a/drivers/fpga/fpga-bridge.c
> +++ b/drivers/fpga/fpga-bridge.c
> @@ -360,7 +360,6 @@ fpga_bridge_register(struct device *parent, const char *name,
>  	bridge->dev.parent = parent;
>  	bridge->dev.of_node = parent->of_node;
>  	bridge->dev.id = id;
> -	of_platform_populate(bridge->dev.of_node, NULL, NULL, &bridge->dev);
>  
>  	ret = dev_set_name(&bridge->dev, "br%d", id);
>  	if (ret)
> @@ -372,6 +371,8 @@ fpga_bridge_register(struct device *parent, const char *name,
>  		return ERR_PTR(ret);
>  	}
>  
> +	of_platform_populate(bridge->dev.of_node, NULL, NULL, &bridge->dev);

It makes sense.

Acked-by: Xu Yilun <yilun.xu@intel.com>

Applied

> +
>  	return bridge;
>  
>  error_device:
> -- 
> 2.40.0
>
diff mbox series

Patch

diff --git a/drivers/fpga/fpga-bridge.c b/drivers/fpga/fpga-bridge.c
index 727704431f61..13918c8c839e 100644
--- a/drivers/fpga/fpga-bridge.c
+++ b/drivers/fpga/fpga-bridge.c
@@ -360,7 +360,6 @@  fpga_bridge_register(struct device *parent, const char *name,
 	bridge->dev.parent = parent;
 	bridge->dev.of_node = parent->of_node;
 	bridge->dev.id = id;
-	of_platform_populate(bridge->dev.of_node, NULL, NULL, &bridge->dev);
 
 	ret = dev_set_name(&bridge->dev, "br%d", id);
 	if (ret)
@@ -372,6 +371,8 @@  fpga_bridge_register(struct device *parent, const char *name,
 		return ERR_PTR(ret);
 	}
 
+	of_platform_populate(bridge->dev.of_node, NULL, NULL, &bridge->dev);
+
 	return bridge;
 
 error_device: