qdev: Introduce DEFINE_PROP_LINK

This property can be used to replace the object_property_add_link in
device code, to add a link to other objects, which is a common pattern.

Signed-off-by: Fam Zheng <famz@redhat.com>
Message-Id: <20170714021509.23681-4-famz@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 18 insertions, 0 deletions

diff --git a/hw/core/qdev-properties.c b/hw/core/qdev-properties.c
index 113ce7df46..5429c63e23 100644
--- a/hw/core/qdev-properties.c
+++ b/hw/core/qdev-properties.c
@@ -1214,3 +1214,21 @@ PropertyInfo qdev_prop_size = {
     .set = set_size,
     .set_default_value = set_default_value_uint,
 };
+
+/* --- object link property --- */
+
+static void create_link_property(Object *obj, Property *prop, Error **errp)
+{
+    Object **child = qdev_get_prop_ptr(DEVICE(obj), prop);
+
+    object_property_add_link(obj, prop->name, prop->link_type,
+                             child,
+                             qdev_prop_allow_set_link_before_realize,
+                             OBJ_PROP_LINK_UNREF_ON_RELEASE,
+                             errp);
+}
+
+PropertyInfo qdev_prop_link = {
+    .name = "link",
+    .create = create_link_property,
+};