[PATCH 3.16.y-ckt 145/180] ACPI / scan: Annotate physical_node_lock in acpi_scan_is_offline()

[Luis Henriques]

3.16.7-ckt11 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: "Rafael J. Wysocki" <rafael.j.wysocki at intel.com>

commit 4c533c801d1c9b5c38458a0e7516e0cf50643782 upstream.

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: caa73ea158de (ACPI / hotplug / driver core: Handle containers in a special way)
Reported-and-tested-by: Xie XiuQi <xiexiuqi at huawei.com>
Reviewed-by: Toshi Kani <toshi.kani at hp.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki at intel.com>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 drivers/acpi/scan.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
index f002835894c1..3d0924ed0b46 100644
--- a/drivers/acpi/scan.c
+++ b/drivers/acpi/scan.c
@@ -214,7 +214,11 @@ 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) {