linux-kernel - [PATCH V2] of/platform: increase refcount of fwnode

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Date:   Fri, 18 Aug 2023 09:59:32 +0800
From:   "Peng Fan (OSS)" <peng.fan@....nxp.com>
To:     robh+dt@...nel.org, krzysztof.kozlowski+dt@...aro.org,
        conor+dt@...nel.org, frowand.list@...il.com,
        andriy.shevchenko@...ux.intel.com, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org
Cc:     isaacmanjarres@...gle.com, rmk+kernel@...linux.org.uk,
        hdegoede@...hat.com, ulf.hansson@...aro.org, rafael@...nel.org,
        Peng Fan <peng.fan@....com>
Subject: [PATCH V2] of/platform: increase refcount of fwnode

From: Peng Fan <peng.fan@....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@....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