[PATCH v2 02/15] hw/qdev: Introduce qdev_unrealize_and_unref()

[Philippe Mathieu-Daudé]

Inspired-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
---
 hw/core/qdev.c         |  9 +++++++++
 include/hw/qdev-core.h | 20 ++++++++++++++++++++
 2 files changed, 29 insertions(+)

diff --git a/hw/core/qdev.c b/hw/core/qdev.c
index d759c4602c..b9ef793d51 100644
--- a/hw/core/qdev.c
+++ b/hw/core/qdev.c
@@ -306,6 +306,15 @@ void qdev_unrealize(DeviceState *dev)
     object_property_set_bool(OBJECT(dev), "realized", false, &error_abort);
 }
 
+bool qdev_unrealize_and_unref(DeviceState *dev, Error **errp)
+{
+    bool ret;
+
+    ret = object_property_set_bool(OBJECT(dev), "realized", false, errp);
+    object_unref(OBJECT(dev));
+    return ret;
+}
+
 static int qdev_assert_realized_properly_cb(Object *obj, void *opaque)
 {
     DeviceState *dev = DEVICE(object_dynamic_cast(obj, TYPE_DEVICE));
diff --git a/include/hw/qdev-core.h b/include/hw/qdev-core.h
index fd11e9a82f..20b9220023 100644
--- a/include/hw/qdev-core.h
+++ b/include/hw/qdev-core.h
@@ -374,6 +374,8 @@ bool qdev_realize(DeviceState *dev, BusState *bus, Error 
**errp);
  * for the only reference to the child device to be held by the parent
  * via the child<> property, and so the reference-count-drop done here
  * would be incorrect. For that use case you want qdev_realize().
+ *
+ * Returns %true on success or %false if an error occured.
  */
 bool qdev_realize_and_unref(DeviceState *dev, BusState *bus, Error **errp);
 
@@ -397,6 +399,24 @@ bool qdev_realize_and_unref(DeviceState *dev, BusState 
*bus, Error **errp);
  * the life of the simulation and should not be unrealized and freed.
  */
 void qdev_unrealize(DeviceState *dev);
+
+/**
+ * qdev_unrealize_and_unref: Unrealize a device and drop a reference
+ * @dev: device to unrealize
+ * @errp: pointer to error object
+ *
+ * Unrealize @dev and drop a reference.
+ * This is like qdev_unrealize(), except the caller must hold a
+ * (private) reference, which is dropped on return regardless of
+ * success or failure.
+ *
+ * Warning: most devices in QEMU do not expect to be unrealized.  Only
+ * devices which are hot-unpluggable should be unrealized (as part of
+ * the unplugging process); all other devices are expected to last for
+ * the life of the simulation and should not be unrealized and freed.
+ */
+bool qdev_unrealize_and_unref(DeviceState *dev, Error **errp);
+
 void qdev_set_legacy_instance_id(DeviceState *dev, int alias_id,
                                  int required_for_version);
 HotplugHandler *qdev_get_bus_hotplug_handler(DeviceState *dev);
-- 
2.38.1