qobject: Modify qobject_ref() to return obj

For convenience and clarity, make it possible to call qobject_ref() at
the time when the reference is associated with a variable, or
argument, by making qobject_ref() return the same pointer as given.
Use that to simplify the callers.

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-Id: <20180419150145.24795-5-marcandre.lureau@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
[Useless change to qobject_ref_impl() dropped, commit message improved
slightly]
Signed-off-by: Markus Armbruster <armbru@redhat.com>

2 files changed, 5 insertions, 8 deletions

diff --git a/qapi/qobject-input-visitor.c b/qapi/qobject-input-visitor.c
index 7a290c4a3f..da57f4cc24 100644
--- a/qapi/qobject-input-visitor.c
+++ b/qapi/qobject-input-visitor.c
@@ -588,8 +588,7 @@ static void qobject_input_type_any(Visitor *v, const char *name, QObject **obj,
         return;
     }
 
-    qobject_ref(qobj);
-    *obj = qobj;
+    *obj = qobject_ref(qobj);
 }
 
 static void qobject_input_type_null(Visitor *v, const char *name,
@@ -677,8 +676,7 @@ static QObjectInputVisitor *qobject_input_visitor_base_new(QObject *obj)
     v->visitor.optional = qobject_input_optional;
     v->visitor.free = qobject_input_free;
 
-    v->root = obj;
-    qobject_ref(obj);
+    v->root = qobject_ref(obj);
 
     return v;
 }
diff --git a/qapi/qobject-output-visitor.c b/qapi/qobject-output-visitor.c
index 3a933b489b..89ffd8a7bf 100644
--- a/qapi/qobject-output-visitor.c
+++ b/qapi/qobject-output-visitor.c
@@ -188,8 +188,8 @@ static void qobject_output_type_any(Visitor *v, const char *name,
                                     QObject **obj, Error **errp)
 {
     QObjectOutputVisitor *qov = to_qov(v);
-    qobject_ref(*obj);
-    qobject_output_add_obj(qov, name, *obj);
+
+    qobject_output_add_obj(qov, name, qobject_ref(*obj));
 }
 
 static void qobject_output_type_null(Visitor *v, const char *name,
@@ -210,8 +210,7 @@ static void qobject_output_complete(Visitor *v, void *opaque)
     assert(qov->root && QSLIST_EMPTY(&qov->stack));
     assert(opaque == qov->result);
 
-    qobject_ref(qov->root);
-    *qov->result = qov->root;
+    *qov->result = qobject_ref(qov->root);
     qov->result = NULL;
 }