qdev: move unrealization of devices from finalize to unparent

Similarly, a bus holds a reference back to the device, and this will
prevent the device from going away as soon as this reference is counted
properly.  To avoid this, move the unrealization of devices to the
unparent callback.  This includes recursively unparenting all the buses
and (after the previous patch) the devices on those buses, which ensures
that the web of references completely disappears for all devices that
reside (in the qdev tree) below the one being unplugged.

After this patch, the qdev tree and the bus<->child relationship is
defined as "A is above B, iff unplugging A will automatically unplug B".

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>

diff --git a/hw/qdev.c b/hw/qdev.c
index 3c1ec7df44f02c3a547852047a844ac4186598bf..6f1b3117fff04bf43b6ba56dda5e811a5238196f 100644 (file)
--- a/hw/qdev.c
+++ b/hw/qdev.c
@@ -738,23 +738,8 @@ static void device_initfn(Object *obj)
 static void device_finalize(Object *obj)
 {
     DeviceState *dev = DEVICE(obj);
-    BusState *bus;
-    DeviceClass *dc = DEVICE_GET_CLASS(dev);
-
-    if (dev->realized) {
-        while (dev->num_child_bus) {
-            bus = QLIST_FIRST(&dev->child_bus);
-            qbus_free(bus);
-        }
-        if (qdev_get_vmsd(dev)) {
-            vmstate_unregister(dev, qdev_get_vmsd(dev), dev);
-        }
-        if (dc->exit) {
-            dc->exit(dev);
-        }
-        if (dev->opts) {
-            qemu_opts_del(dev->opts);
-        }
+    if (dev->opts) {
+        qemu_opts_del(dev->opts);
     }
 }
 
@@ -771,8 +756,22 @@ static void device_class_base_init(ObjectClass *class, void *data)
 static void device_unparent(Object *obj)
 {
     DeviceState *dev = DEVICE(obj);
+    DeviceClass *dc = DEVICE_GET_CLASS(dev);
+    BusState *bus;
 
-    if (dev->parent_bus != NULL) {
+    while (dev->num_child_bus) {
+        bus = QLIST_FIRST(&dev->child_bus);
+        qbus_free(bus);
+    }
+    if (dev->realized) {
+        if (qdev_get_vmsd(dev)) {
+            vmstate_unregister(dev, qdev_get_vmsd(dev), dev);
+        }
+        if (dc->exit) {
+            dc->exit(dev);
+        }
+    }
+    if (dev->parent_bus) {
         bus_remove_child(dev->parent_bus, dev);
     }
 }