linux-kernel - [PATCH 5.10 002/121] ACPI: Get acpi_devices parent from the parent field

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Date:   Mon, 29 Nov 2021 19:17:13 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        Sakari Ailus <sakari.ailus@...ux.intel.com>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>
Subject: [PATCH 5.10 002/121] ACPI: Get acpi_devices parent from the parent field

From: Sakari Ailus <sakari.ailus@...ux.intel.com>

commit 9054fc6d57e80c27c0b0632966416144f2092c2b upstream.

Printk modifier %pfw is used to print the full path of the device name.
This is obtained device by device until a device no longer has a parent.

On ACPI getting the parent fwnode is done by calling acpi_get_parent()
which tries to down() a semaphore. But local IRQs are now disabled in
vprintk_store() before the mutex is acquired. This is obviously a problem.

Luckily struct device, embedded in struct acpi_device, has a parent field
already. Use that field to get the parent instead of relying on
acpi_get_parent().

Fixes: 3bd32d6a2ee6 ("lib/vsprintf: Add %pfw conversion specifier for printing fwnode names")
Cc: 5.5+ <stable@...r.kernel.org> # 5.5+
Signed-off-by: Sakari Ailus <sakari.ailus@...ux.intel.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 drivers/acpi/property.c |   11 +++--------
 1 file changed, 3 insertions(+), 8 deletions(-)

--- a/drivers/acpi/property.c
+++ b/drivers/acpi/property.c
@@ -1110,15 +1110,10 @@ struct fwnode_handle *acpi_node_get_pare
 		/* All data nodes have parent pointer so just return that */
 		return to_acpi_data_node(fwnode)->parent;
 	} else if (is_acpi_device_node(fwnode)) {
-		acpi_handle handle, parent_handle;
+		struct device *dev = to_acpi_device_node(fwnode)->dev.parent;
 
-		handle = to_acpi_device_node(fwnode)->handle;
-		if (ACPI_SUCCESS(acpi_get_parent(handle, &parent_handle))) {
-			struct acpi_device *adev;
-
-			if (!acpi_bus_get_device(parent_handle, &adev))
-				return acpi_fwnode_handle(adev);
-		}
+		if (dev)
+			return acpi_fwnode_handle(to_acpi_device(dev));
 	}
 
 	return NULL;