[Qemu-devel] [PATCH] qdev: Fix QOM unrealize behavior

["Andreas Färber" <afaerber@suse.de>]

Since commit 249d41720b7dfbb5951b430b9eefdbee7464f515 (qdev: Prepare
"realized" property) setting realized = true would register the device's
VMStateDescription, but realized = false would not unregister it. Fix that.

Moving the code from unparenting also revealed that we were calling
DeviceClass::init through DeviceClass::realize as interim solution but
DeviceClass::exit still at unparenting time with a realized check.
Make this symmetrical by implementing DeviceClass::unrealize to call it,
while we're setting realized = false in the unparenting path.
The only other unrealize user is mac_nvram, which can safely override it.

Thus, mark DeviceClass::exit as obsolete, new devices should implement
DeviceClass::unrealize instead.

Cc: qemu-stable@nongnu.org
Signed-off-by: Andreas Färber <afaerber@suse.de>
---
 Seems I talked about what this patch was doing in the QMP event context but
 never sent it out... here it is in an updated version.

 hw/core/qdev.c         | 25 ++++++++++++++++++-------
 include/hw/qdev-core.h |  2 +-
 2 files changed, 19 insertions(+), 8 deletions(-)

diff --git a/hw/core/qdev.c b/hw/core/qdev.c
index e2bb37d..bab4ed7 100644
--- a/hw/core/qdev.c
+++ b/hw/core/qdev.c
@@ -182,6 +182,19 @@ static void device_realize(DeviceState *dev, Error **err)
     }
 }
 
+static void device_unrealize(DeviceState *dev, Error **errp)
+{
+    DeviceClass *dc = DEVICE_GET_CLASS(dev);
+
+    if (dc->exit) {
+        int rc = dc->exit(dev);
+        if (rc < 0) {
+            error_setg(errp, "Device exit failed.");
+            return;
+        }
+    }
+}
+
 void qdev_set_legacy_instance_id(DeviceState *dev, int alias_id,
                                  int required_for_version)
 {
@@ -694,6 +707,9 @@ static void device_set_realized(Object *obj, bool value, Error **err)
             device_reset(dev);
         }
     } else if (!value && dev->realized) {
+        if (qdev_get_vmsd(dev)) {
+            vmstate_unregister(dev, qdev_get_vmsd(dev), dev);
+        }
         if (dc->unrealize) {
             dc->unrealize(dev, &local_err);
         }
@@ -764,7 +780,6 @@ 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;
     QObject *event_data;
     bool have_realized = dev->realized;
@@ -774,12 +789,7 @@ static void device_unparent(Object *obj)
         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);
-        }
+        object_property_set_bool(obj, false, "realized", NULL);
     }
     if (dev->parent_bus) {
         bus_remove_child(dev->parent_bus, dev);
@@ -809,6 +819,7 @@ static void device_class_init(ObjectClass *class, void *data)
 
     class->unparent = device_unparent;
     dc->realize = device_realize;
+    dc->unrealize = device_unrealize;
 }
 
 void device_reset(DeviceState *dev)
diff --git a/include/hw/qdev-core.h b/include/hw/qdev-core.h
index 547fbc7..cf83d54 100644
--- a/include/hw/qdev-core.h
+++ b/include/hw/qdev-core.h
@@ -96,7 +96,7 @@ typedef struct DeviceClass {
     /* Private to qdev / bus.  */
     qdev_initfn init; /* TODO remove, once users are converted to realize */
     qdev_event unplug;
-    qdev_event exit;
+    qdev_event exit; /* TODO remove, once users are converted to unrealize */
     const char *bus_type;
 } DeviceClass;
 
-- 
1.8.1.4