[Qemu-devel] [PATCH v2] qdev: Don't assume existence of parent bus on unparenting

["Andreas Färber" <afaerber@suse.de>]

Commit 667d22d1ae59da46b4c1fbd094ca61145f19b8c3 (qdev: move bus removal
to object_unparent) made the assumption that at unparenting time
parent_bus is not NULL. This assumption is unjustified since
object_unparent() may well be called directly after object_initialize(),
without any qdev_set_parent_bus().

This did not cause any issues yet because qdev_[try_]create() does call
qdev_set_parent_bus(), falling back to SysBus if unsupplied.

While at it, ensure that this new function uses the device_ prefix and
make the name more neutral in light of this semantic change.

Reported-by: Eduardo Habkost <ehabkost@redhat.com>
Signed-off-by: Andreas Färber <afaerber@suse.de>
Cc: Paolo Bonzini <pbonzini@redhat.com>
---
 Planning to insert this before the final CPU-as-a-device patch on qom-cpu,
 to avoid a regression for, e.g., -cpu Haswell,enforce if unsupported by host.

 This supersedes my cosmetic patch in the "QOM realize, device-only" series:

 v1 -> v2:
 * Make bus removal conditional on parent bus
 * Rename function further

 hw/qdev.c |    8 +++++---
 1 Datei geändert, 5 Zeilen hinzugefügt(+), 3 Zeilen entfernt(-)

diff --git a/hw/qdev.c b/hw/qdev.c
index f2c2484..e2a5c57 100644
--- a/hw/qdev.c
+++ b/hw/qdev.c
@@ -698,16 +698,18 @@ static void device_class_base_init(ObjectClass *class, void *data)
     klass->props = NULL;
 }
 
-static void qdev_remove_from_bus(Object *obj)
+static void device_unparent(Object *obj)
 {
     DeviceState *dev = DEVICE(obj);
 
-    bus_remove_child(dev->parent_bus, dev);
+    if (dev->parent_bus != NULL) {
+        bus_remove_child(dev->parent_bus, dev);
+    }
 }
 
 static void device_class_init(ObjectClass *class, void *data)
 {
-    class->unparent = qdev_remove_from_bus;
+    class->unparent = device_unparent;
 }
 
 void device_reset(DeviceState *dev)
-- 
1.7.10.4