[PATCH v1 3/3] ACPI: scan: Use acpi_bus_get_primary_device()

[Rafael J. Wysocki]

From: "Rafael J. Wysocki" <rafael.j.wysocki@xxxxxxxxx>

The acpi_get_first_physical_node() usage in acpi_create_video_bus_device()
is generally unsafe because in theory the device returned by it may be
freed at any time.

Address this issues by using acpi_bus_get_primary_device() instead of
acpi_get_first_physical_node() and dropping the device reference
acquired by it after registering the child.

Fixes: 6ab3532b4c98 ("ACPI: video: Switch over to auxiliary bus type")
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
---
 drivers/acpi/scan.c |   20 +++++++++-----------
 1 file changed, 9 insertions(+), 11 deletions(-)

--- a/drivers/acpi/scan.c
+++ b/drivers/acpi/scan.c
@@ -2203,29 +2203,27 @@ static void acpi_create_video_bus_device
 	struct auxiliary_device *aux_dev;
 	static unsigned int aux_dev_id;
 
+	struct device *phys_parent __free(put_device) = acpi_bus_get_primary_device(parent);
+	if (!phys_parent)
+		return;
+
 	aux_dev = kzalloc_obj(*aux_dev);
 	if (!aux_dev)
 		return;
 
 	aux_dev->id = aux_dev_id++;
 	aux_dev->name = "video_bus";
-	aux_dev->dev.parent = acpi_get_first_physical_node(parent);
-	if (!aux_dev->dev.parent)
-		goto err;
-
+	aux_dev->dev.parent = phys_parent;
 	aux_dev->dev.release = acpi_video_bus_device_release;
 
-	if (auxiliary_device_init(aux_dev))
-		goto err;
+	if (auxiliary_device_init(aux_dev)) {
+		kfree(aux_dev);
+		return;
+	}
 
 	ACPI_COMPANION_SET(&aux_dev->dev, adev);
 	if (__auxiliary_device_add(aux_dev, "acpi"))
 		auxiliary_device_uninit(aux_dev);
-
-	return;
-
-err:
-	kfree(aux_dev);
 }
 
 struct acpi_scan_system_dev {