ACPI / scan: Annotate physical_node_lock in acpi_scan_is_offline()

acpi_scan_is_offline() may be called under the physical_node_lock
lock of the given device object's parent, so prevent lockdep from
complaining about that by annotating that instance with
SINGLE_DEPTH_NESTING.

Fixes: caa73ea1 (ACPI / hotplug / driver core: Handle containers in a special way)
Reported-and-tested-by: Xie XiuQi <xiexiuqi@huawei.com>
Reviewed-by: Toshi Kani <toshi.kani@hp.com>
Cc: 3.14+ <stable@vger.kernel.org> # 3.14+
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/acpi/scan.c

@@ -375,7 +375,11 @@ bool acpi_scan_is_offline(struct acpi_device *adev, bool uevent)
 	struct acpi_device_physical_node *pn;
 	bool offline = true;
 
-	mutex_lock(&adev->physical_node_lock);
+	/*
+	 * acpi_container_offline() calls this for all of the container's
+	 * children under the container's physical_node_lock lock.
+	 */
+	mutex_lock_nested(&adev->physical_node_lock, SINGLE_DEPTH_NESTING);
 
 	list_for_each_entry(pn, &adev->physical_node_list, node)
 		if (device_supports_offline(pn->dev) && !pn->dev->offline) {