[PATCH V2] of/platform: increase refcount of fwnode

[PATCH V2] of/platform: increase refcount of fwnode

[Peng Fan (OSS)]

From: Peng Fan <peng.fan@nxp.com>

commit 0f8e5651095b
("of/platform: Propagate firmware node by calling device_set_node()")
use of_fwnode_handle to replace of_node_get, which introduces a side
effect that the refcount is not increased. Then the out of tree
jailhouse hypervisor enable/disable test will trigger kernel dump in
of_overlay_remove, with the following sequence
"
   of_changeset_revert(&overlay_changeset);
   of_changeset_destroy(&overlay_changeset);
   of_overlay_remove(&overlay_id);
"

So increase the refcount to avoid issues.

This patch also release the refcount when releasing amba device to avoid
refcount leakage.

Fixes: 0f8e5651095b ("of/platform: Propagate firmware node by calling device_set_node()")
Signed-off-by: Peng Fan <peng.fan@nxp.com>
---

V2:
 - Per Andy's comment, use of_fwnode_handle(of_node_get(np))
 - release amba device of_node refcount when releasing amba device, this is
 done from code inspection, no test.


 drivers/amba/bus.c    | 1 +
 drivers/of/platform.c | 4 ++--
 2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/amba/bus.c b/drivers/amba/bus.c
index ce88af9eb562..09e72967b8ab 100644
--- a/drivers/amba/bus.c
+++ b/drivers/amba/bus.c
@@ -528,6 +528,7 @@ static void amba_device_release(struct device *dev)
 {
 	struct amba_device *d = to_amba_device(dev);
 
+	of_node_put(d->dev.of_node);
 	if (d->res.parent)
 		release_resource(&d->res);
 	mutex_destroy(&d->periphid_lock);
diff --git a/drivers/of/platform.c b/drivers/of/platform.c
index 267d8c9a5612..d328bbb679c7 100644
--- a/drivers/of/platform.c
+++ b/drivers/of/platform.c
@@ -175,7 +175,7 @@ struct platform_device *of_device_alloc(struct device_node *np,
 	}
 
 	/* setup generic device info */
-	device_set_node(&dev->dev, of_fwnode_handle(np));
+	device_set_node(&dev->dev, of_fwnode_handle(of_node_get(np)));
 	dev->dev.parent = parent ? : &platform_bus;
 
 	if (bus_id)
@@ -273,7 +273,7 @@ static struct amba_device *of_amba_device_create(struct device_node *node,
 	dev->dev.dma_mask = &dev->dev.coherent_dma_mask;
 
 	/* setup generic device info */
-	device_set_node(&dev->dev, of_fwnode_handle(node));
+	device_set_node(&dev->dev, of_fwnode_handle(of_node_get(node)));
 	dev->dev.parent = parent ? : &platform_bus;
 	dev->dev.platform_data = platform_data;
 	if (bus_id)
-- 
2.37.1

Re: [PATCH V2] of/platform: increase refcount of fwnode

[Andy Shevchenko]

On Fri, Aug 18, 2023 at 09:59:32AM +0800, Peng Fan (OSS) wrote:
> From: Peng Fan <peng.fan@nxp.com>
> 
> commit 0f8e5651095b
> ("of/platform: Propagate firmware node by calling device_set_node()")
> use of_fwnode_handle to replace of_node_get, which introduces a side
> effect that the refcount is not increased. Then the out of tree
> jailhouse hypervisor enable/disable test will trigger kernel dump in
> of_overlay_remove, with the following sequence
> "
>    of_changeset_revert(&overlay_changeset);
>    of_changeset_destroy(&overlay_changeset);
>    of_overlay_remove(&overlay_id);
> "
> 
> So increase the refcount to avoid issues.

...

> This patch also release the refcount when releasing amba device to avoid
> refcount leakage.

> --- a/drivers/amba/bus.c
> +++ b/drivers/amba/bus.c
> @@ -528,6 +528,7 @@ static void amba_device_release(struct device *dev)
>  {
>  	struct amba_device *d = to_amba_device(dev);
>  
> +	of_node_put(d->dev.of_node);
>  	if (d->res.parent)
>  		release_resource(&d->res);
>  	mutex_destroy(&d->periphid_lock);

As I said, this change should be in a separate patch with the correct Fixes tag.

> index 267d8c9a5612..d328bbb679c7 100644
> --- a/drivers/of/platform.c
> +++ b/drivers/of/platform.c
> @@ -175,7 +175,7 @@ struct platform_device *of_device_alloc(struct device_node *np,
>  	}
>  
>  	/* setup generic device info */
> -	device_set_node(&dev->dev, of_fwnode_handle(np));
> +	device_set_node(&dev->dev, of_fwnode_handle(of_node_get(np)));
>  	dev->dev.parent = parent ? : &platform_bus;
>  
>  	if (bus_id)
> @@ -273,7 +273,7 @@ static struct amba_device *of_amba_device_create(struct device_node *node,
>  	dev->dev.dma_mask = &dev->dev.coherent_dma_mask;
>  
>  	/* setup generic device info */
> -	device_set_node(&dev->dev, of_fwnode_handle(node));
> +	device_set_node(&dev->dev, of_fwnode_handle(of_node_get(node)));
>  	dev->dev.parent = parent ? : &platform_bus;
>  	dev->dev.platform_data = platform_data;
>  	if (bus_id)

Without AMBA changes,
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
thank you for fixing this!

-- 
With Best Regards,
Andy Shevchenko