qdev: Move bus properties to abstract superclasses

In qdev, each bus in practice identified an abstract superclass, but
this was mostly hidden.  In QOM, instead, these abstract classes are
explicit so we can move bus properties there.

All bus property walks are removed, and all device property walks
are changed to look along the class hierarchy instead.

We would have duplicates if class A defines some properties and its
subclass B does not define any, because class_b->props will be
left equal to class_a->props.

The solution here is to reintroduce the class_base_init TypeInfo
callback, that was present in one of the early QOM versions but
removed (on my request...) before committing.

This breaks global bus properties, an obscure feature when used
with the command-line which is actually useful and used when used by
backwards-compatible machine types.  So this patch also adjusts the
global bus properties in hw/pc_piix.c to refer to the abstract class.

Globals and other properties must be modified in the same patch to
avoid complications related to initialization ordering.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Andreas Färber <afaerber@suse.de>

1 files changed, 21 insertions, 26 deletions

diff --git a/hw/qdev.c b/hw/qdev.c
index a9a9f891da..f239902291 100644
--- a/hw/qdev.c
+++ b/hw/qdev.c
@@ -45,18 +45,6 @@ const VMStateDescription *qdev_get_vmsd(DeviceState *dev)
     return dc->vmsd;
 }
 
-BusInfo *qdev_get_bus_info(DeviceState *dev)
-{
-    DeviceClass *dc = DEVICE_GET_CLASS(dev);
-    return dc->bus_info;
-}
-
-Property *qdev_get_props(DeviceState *dev)
-{
-    DeviceClass *dc = DEVICE_GET_CLASS(dev);
-    return dc->props;
-}
-
 const char *qdev_fw_name(DeviceState *dev)
 {
     DeviceClass *dc = DEVICE_GET_CLASS(dev);
@@ -78,20 +66,12 @@ static void qdev_property_add_legacy(DeviceState *dev, Property *prop,
 
 void qdev_set_parent_bus(DeviceState *dev, BusState *bus)
 {
-    Property *prop;
-
     if (qdev_hotplug) {
         assert(bus->allow_hotplug);
     }
 
     dev->parent_bus = bus;
     QTAILQ_INSERT_HEAD(&bus->children, dev, sibling);
-
-    for (prop = qdev_get_bus_info(dev)->props; prop && prop->name; prop++) {
-        qdev_property_add_legacy(dev, prop, NULL);
-        qdev_property_add_static(dev, prop, NULL);
-    }
-    qdev_prop_set_defaults(dev, dev->parent_bus->info->props);
 }
 
 /* Create a new device.  This only initializes the device state structure
@@ -618,6 +598,7 @@ void qdev_property_add_static(DeviceState *dev, Property *prop,
 static void device_initfn(Object *obj)
 {
     DeviceState *dev = DEVICE(obj);
+    ObjectClass *class;
     Property *prop;
 
     if (qdev_hotplug) {
@@ -628,12 +609,15 @@ static void device_initfn(Object *obj)
     dev->instance_id_alias = -1;
     dev->state = DEV_STATE_CREATED;
 
-    for (prop = qdev_get_props(dev); prop && prop->name; prop++) {
-        qdev_property_add_legacy(dev, prop, NULL);
-        qdev_property_add_static(dev, prop, NULL);
-    }
-
-    qdev_prop_set_defaults(dev, qdev_get_props(dev));
+    class = object_get_class(OBJECT(dev));
+    do {
+        for (prop = DEVICE_CLASS(class)->props; prop && prop->name; prop++) {
+            qdev_property_add_legacy(dev, prop, NULL);
+            qdev_property_add_static(dev, prop, NULL);
+        }
+        qdev_prop_set_defaults(dev, DEVICE_CLASS(class)->props);
+        class = object_class_get_parent(class);
+    } while (class != object_class_by_name(TYPE_DEVICE));
 }
 
 /* Unlink device from bus and free the structure.  */
@@ -661,6 +645,16 @@ static void device_finalize(Object *obj)
     QTAILQ_REMOVE(&dev->parent_bus->children, dev, sibling);
 }
 
+static void device_class_base_init(ObjectClass *class, void *data)
+{
+    DeviceClass *klass = DEVICE_CLASS(class);
+
+    /* We explicitly look up properties in the superclasses,
+     * so do not propagate them to the subclasses.
+     */
+    klass->props = NULL;
+}
+
 void device_reset(DeviceState *dev)
 {
     DeviceClass *klass = DEVICE_GET_CLASS(dev);
@@ -687,6 +681,7 @@ static TypeInfo device_type_info = {
     .instance_size = sizeof(DeviceState),
     .instance_init = device_initfn,
     .instance_finalize = device_finalize,
+    .class_base_init = device_class_base_init,
     .abstract = true,
     .class_size = sizeof(DeviceClass),
 };