Re: [PATCH] ACPI / scan: Annotate physical_node_lock in acpi_scan_is_offline()

From: Hanjun Guo
Date: Mon Apr 13 2015 - 04:27:31 EST

On 2015å04æ11æ 07:31, Rafael J. Wysocki wrote:
From: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>

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

I think this is trigged by setting acpi_force_hot_remove to 1,
in acpi_scan_hot_remove():

if (device->handler && device->handler->hotplug.demand_offline
&& !acpi_force_hot_remove) {
if (!acpi_scan_is_offline(device, true))
return -EBUSY;
} else {
int error = acpi_scan_try_to_offline(device);
if (error)
return error;

then the container device will be removed by acpi_scan_try_to_offline(),
let's wait for Xiuqi's test result.


Reported-by: Xie XiuQi <xiexiuqi@xxxxxxxxxx>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
drivers/acpi/scan.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)

Index: linux-pm/drivers/acpi/scan.c
--- linux-pm.orig/drivers/acpi/scan.c
+++ linux-pm/drivers/acpi/scan.c
@@ -298,7 +298,11 @@ bool acpi_scan_is_offline(struct acpi_de
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) {

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