qdev: drop extra references at creation time

qdev_free and qbus_free have to do unparent+unref, because nobody else
drops the initial reference (the one included by object_initialize)
before them.

For device_init_func and do_device_add, this is trivially correct,
since the DeviceState goes out of scope.

For qdev_create, qdev_try_create and qbus_init, it is a bit more tricky.
What we are doing here is just assuming that the caller knows what it's
doing, and won't call qdev_free/qbus_free while the device is still there.
This is a pretty reasonable assumption and (behind the scenes) is also
what GObject/GTK does.  GTK actually has a "floating reference" that
goes away as soon as the caller does gtk_container_add or something
like that, but in the end qbus_init and qdev_try_create are already
adding the new object to its qdev parent!  So in the end the two solutions
are the same.

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

1 files changed, 1 insertions, 0 deletions

diff --git a/vl.c b/vl.c
index f094f04a2c..315598994f 100644
--- a/vl.c
+++ b/vl.c
@@ -2236,6 +2236,7 @@ static int device_init_func(QemuOpts *opts, void *opaque)
     dev = qdev_device_add(opts);
     if (!dev)
         return -1;
+    object_unref(OBJECT(dev));
     return 0;
 }