ACPI / hotplug: Add demand_offline hotplug profile flag
Add a new ACPI hotplug profile flag, demand_offline, such that if
set for the given ACPI device object's scan handler, it will cause
acpi_scan_hot_remove() to check if that device object's physical
companions are offline upfront and fail the hot removal if that
is not the case.
That flag will be useful to overcome a problem with containers on
some system where they can only be hot-removed after some cleanup
operations carried out by user space, which needs to be notified
of the container hot-removal before the kernel attempts to offline
devices in the container. In those cases the current implementation
of acpi_scan_hot_remove() is not sufficient, because it first tries
to offline the devices in the container and only if that is
suffcessful it tries to offline the container itself. As a result,
the container hot-removal notification is not delivered to user space
at the right time.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
index 5383c81..65243b9 100644
--- a/drivers/acpi/scan.c
+++ b/drivers/acpi/scan.c
@@ -126,6 +126,24 @@
}
static DEVICE_ATTR(modalias, 0444, acpi_device_modalias_show, NULL);
+static bool acpi_scan_is_offline(struct acpi_device *adev)
+{
+ struct acpi_device_physical_node *pn;
+ bool offline = true;
+
+ mutex_lock(&adev->physical_node_lock);
+
+ list_for_each_entry(pn, &adev->physical_node_list, node)
+ if (device_supports_offline(pn->dev) && !pn->dev->offline) {
+ kobject_uevent(&pn->dev->kobj, KOBJ_CHANGE);
+ offline = false;
+ break;
+ }
+
+ mutex_unlock(&adev->physical_node_lock);
+ return offline;
+}
+
static acpi_status acpi_bus_offline(acpi_handle handle, u32 lvl, void *data,
void **ret_p)
{
@@ -196,12 +214,11 @@
return AE_OK;
}
-static int acpi_scan_hot_remove(struct acpi_device *device)
+static int acpi_scan_try_to_offline(struct acpi_device *device)
{
acpi_handle handle = device->handle;
- struct device *errdev;
+ struct device *errdev = NULL;
acpi_status status;
- unsigned long long sta;
/*
* Carry out two passes here and ignore errors in the first pass,
@@ -212,7 +229,6 @@
*
* If the first pass is successful, the second one isn't needed, though.
*/
- errdev = NULL;
status = acpi_walk_namespace(ACPI_TYPE_ANY, handle, ACPI_UINT32_MAX,
NULL, acpi_bus_offline, (void *)false,
(void **)&errdev);
@@ -241,6 +257,23 @@
return -EBUSY;
}
}
+ return 0;
+}
+
+static int acpi_scan_hot_remove(struct acpi_device *device)
+{
+ acpi_handle handle = device->handle;
+ unsigned long long sta;
+ acpi_status status;
+
+ if (device->handler->hotplug.demand_offline && !acpi_force_hot_remove) {
+ if (!acpi_scan_is_offline(device))
+ return -EBUSY;
+ } else {
+ int error = acpi_scan_try_to_offline(device);
+ if (error)
+ return error;
+ }
ACPI_DEBUG_PRINT((ACPI_DB_INFO,
"Hot-removing device %s...\n", dev_name(&device->dev)));