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>

2 files changed, 39 insertions, 5 deletions

diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
index 5383c81a8a1b..65243b9dd868 100644
--- a/drivers/acpi/scan.c
+++ b/drivers/acpi/scan.c
@@ -126,6 +126,24 @@ acpi_device_modalias_show(struct device *dev, struct device_attribute *attr, cha
 }
 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 @@ static acpi_status acpi_bus_online(acpi_handle handle, u32 lvl, void *data,
         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 @@ static int acpi_scan_hot_remove(struct acpi_device *device)
          *
          * 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 @@ static int acpi_scan_hot_remove(struct acpi_device *device)
                         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)));
diff --git a/include/acpi/acpi_bus.h b/include/acpi/acpi_bus.h
index 7135fe3d6daa..48d302501539 100644
--- a/include/acpi/acpi_bus.h
+++ b/include/acpi/acpi_bus.h
@@ -91,8 +91,9 @@ struct acpi_device;
 
 struct acpi_hotplug_profile {
         struct kobject kobj;
-        bool enabled:1;
         int (*scan_dependent)(struct acpi_device *adev);
+        bool enabled:1;
+        bool demand_offline:1;
 };
 
 static inline struct acpi_hotplug_profile *to_acpi_hotplug_profile(