ACPI / scan: Define non-empty device removal handler

If an ACPI namespace node is removed (usually, as a result of a
table unload), and there is a data object attached to that node,
acpi_ns_delete_node() executes the removal handler submitted to
acpi_attach_data() for that object.  That handler is currently empty
for struct acpi_device objects, so it is necessary to detach those
objects from the corresponding ACPI namespace nodes in advance every
time a table unload may happen.  That is cumbersome and inefficient
and leads to some design constraints that turn out to be quite
inconvenient (in particular, struct acpi_device objects cannot be
registered for namespace nodes representing devices that are not
reported as present or functional by _STA).

For this reason, introduce a non-empty removal handler for ACPI
device objects that will unregister them when their ACPI namespace
nodes go away.

This code modification alone should not change functionality except
for the ordering of the ACPI hotplug workqueue which should not
matter (without subsequent code changes).

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Tested-by: Mika Westerberg <mika.westerberg@linux.intel.com>

1 files changed, 5 insertions, 1 deletions

diff --git a/drivers/acpi/osl.c b/drivers/acpi/osl.c
index 54a20ff4b864..5b9a785e2155 100644
--- a/drivers/acpi/osl.c
+++ b/drivers/acpi/osl.c
@@ -1215,6 +1215,10 @@ acpi_status acpi_hotplug_execute(acpi_hp_callback func, void *data, u32 src)
 	return AE_OK;
 }
 
+bool acpi_queue_hotplug_work(struct work_struct *work)
+{
+	return queue_work(kacpi_hotplug_wq, work);
+}
 
 acpi_status
 acpi_os_create_semaphore(u32 max_units, u32 initial_units, acpi_handle * handle)
@@ -1794,7 +1798,7 @@ acpi_status __init acpi_os_initialize1(void)
 {
 	kacpid_wq = alloc_workqueue("kacpid", 0, 1);
 	kacpi_notify_wq = alloc_workqueue("kacpi_notify", 0, 1);
-	kacpi_hotplug_wq = alloc_workqueue("kacpi_hotplug", 0, 1);
+	kacpi_hotplug_wq = alloc_ordered_workqueue("kacpi_hotplug", 0);
 	BUG_ON(!kacpid_wq);
 	BUG_ON(!kacpi_notify_wq);
 	BUG_ON(!kacpi_hotplug_wq);