9 files changed, 160 insertions, 26 deletions

diff --git a/backends/rng.c b/backends/rng.c
index 85cb83f5e1..8b8d5a4973 100644
--- a/backends/rng.c
+++ b/backends/rng.c
@@ -12,6 +12,7 @@
 
 #include "sysemu/rng.h"
 #include "qapi/qmp/qerror.h"
+#include "qom/object_interfaces.h"
 
 void rng_backend_request_entropy(RngBackend *s, size_t size,
                                  EntropyReceiveFunc *receive_entropy,
@@ -40,9 +41,9 @@ static bool rng_backend_prop_get_opened(Object *obj, Error **errp)
     return s->opened;
 }
 
-void rng_backend_open(RngBackend *s, Error **errp)
+static void rng_backend_complete(UserCreatable *uc, Error **errp)
 {
-    object_property_set_bool(OBJECT(s), true, "opened", errp);
+    object_property_set_bool(OBJECT(uc), true, "opened", errp);
 }
 
 static void rng_backend_prop_set_opened(Object *obj, bool value, Error **errp)
@@ -76,13 +77,25 @@ static void rng_backend_init(Object *obj)
                              NULL);
 }
 
+static void rng_backend_class_init(ObjectClass *oc, void *data)
+{
+    UserCreatableClass *ucc = USER_CREATABLE_CLASS(oc);
+
+    ucc->complete = rng_backend_complete;
+}
+
 static const TypeInfo rng_backend_info = {
     .name = TYPE_RNG_BACKEND,
     .parent = TYPE_OBJECT,
     .instance_size = sizeof(RngBackend),
     .instance_init = rng_backend_init,
     .class_size = sizeof(RngBackendClass),
+    .class_init = rng_backend_class_init,
     .abstract = true,
+    .interfaces = (InterfaceInfo[]) {
+        { TYPE_USER_CREATABLE },
+        { }
+    }
 };
 
 static void register_types(void)
diff --git a/hw/virtio/virtio-rng.c b/hw/virtio/virtio-rng.c
index 755fdee628..a16e3bc52e 100644
--- a/hw/virtio/virtio-rng.c
+++ b/hw/virtio/virtio-rng.c
@@ -15,6 +15,7 @@
 #include "hw/virtio/virtio.h"
 #include "hw/virtio/virtio-rng.h"
 #include "sysemu/rng.h"
+#include "qom/object_interfaces.h"
 
 static bool is_guest_ready(VirtIORNG *vrng)
 {
@@ -148,6 +149,14 @@ static void virtio_rng_device_realize(DeviceState *dev, Error **errp)
     if (vrng->conf.rng == NULL) {
         vrng->conf.default_backend = RNG_RANDOM(object_new(TYPE_RNG_RANDOM));
 
+        user_creatable_complete(OBJECT(vrng->conf.default_backend),
+                                &local_err);
+        if (local_err) {
+            error_propagate(errp, local_err);
+            object_unref(OBJECT(vrng->conf.default_backend));
+            return;
+        }
+
         object_property_add_child(OBJECT(dev),
                                   "default-backend",
                                   OBJECT(vrng->conf.default_backend),
@@ -166,12 +175,6 @@ static void virtio_rng_device_realize(DeviceState *dev, Error **errp)
         return;
     }
 
-    rng_backend_open(vrng->rng, &local_err);
-    if (local_err) {
-        error_propagate(errp, local_err);
-        return;
-    }
-
     vrng->vq = virtio_add_queue(vdev, 8, handle_input);
 
     assert(vrng->conf.max_bytes <= INT64_MAX);
diff --git a/include/qom/object_interfaces.h b/include/qom/object_interfaces.h
new file mode 100644
index 0000000000..b7922833e1
--- /dev/null
+++ b/include/qom/object_interfaces.h
@@ -0,0 +1,62 @@
+#ifndef OBJECT_INTERFACES_H
+#define OBJECT_INTERFACES_H
+
+#include "qom/object.h"
+
+#define TYPE_USER_CREATABLE "user-creatable"
+
+#define USER_CREATABLE_CLASS(klass) \
+     OBJECT_CLASS_CHECK(UserCreatableClass, (klass), \
+                        TYPE_USER_CREATABLE)
+#define USER_CREATABLE_GET_CLASS(obj) \
+     OBJECT_GET_CLASS(UserCreatableClass, (obj), \
+                      TYPE_USER_CREATABLE)
+#define USER_CREATABLE(obj) \
+     INTERFACE_CHECK(UserCreatable, (obj), \
+                     TYPE_USER_CREATABLE)
+
+
+typedef struct UserCreatable {
+    /* <private> */
+    Object Parent;
+} UserCreatable;
+
+/**
+ * UserCreatableClass:
+ * @parent_class: the base class
+ * @complete: callback to be called after @obj's properties are set.
+ *
+ * Interface is designed to work with -object/object-add/object_add
+ * commands.
+ * Interface is mandatory for objects that are designed to be user
+ * creatable (i.e. -object/object-add/object_add, will accept only
+ * objects that inherit this interface).
+ *
+ * Interface also provides an optional ability to do the second
+ * stage * initialization of the object after its properties were
+ * set.
+ *
+ * For objects created without using -object/object-add/object_add,
+ * @user_creatable_complete() wrapper should be called manually if
+ * object's type implements USER_CREATABLE interface and needs
+ * complete() callback to be called.
+ */
+typedef struct UserCreatableClass {
+    /* <private> */
+    InterfaceClass parent_class;
+
+    /* <public> */
+    void (*complete)(UserCreatable *uc, Error **errp);
+} UserCreatableClass;
+
+/**
+ * user_creatable_complete:
+ * @obj: the object whose complete() method is called if defined
+ * @errp: if an error occurs, a pointer to an area to store the error
+ *
+ * Wrapper to call complete() method if one of types it's inherited
+ * from implements USER_CREATABLE interface, otherwise the call does
+ * nothing.
+ */
+void user_creatable_complete(Object *obj, Error **errp);
+#endif
diff --git a/include/sysemu/rng.h b/include/sysemu/rng.h
index 7637fac52d..0a27c9b88c 100644
--- a/include/sysemu/rng.h
+++ b/include/sysemu/rng.h
@@ -79,15 +79,4 @@ void rng_backend_request_entropy(RngBackend *s, size_t size,
  * to stop tracking any request.
  */
 void rng_backend_cancel_requests(RngBackend *s);
-
-/**
- * rng_backend_open:
- * @s: the backend to open
- * @errp: a pointer to return the #Error object if an error occurs.
- *
- * This function will open the backend if it is not already open.  Calling this
- * function on an already opened backend will not result in an error.
- */
-void rng_backend_open(RngBackend *s, Error **errp);
-
 #endif
diff --git a/monitor.c b/monitor.c
index 80456fbe5b..cba56bc4b7 100644
--- a/monitor.c
+++ b/monitor.c
@@ -288,8 +288,8 @@ void monitor_flush(Monitor *mon)
 
     if (len && !mon->mux_out) {
         rc = qemu_chr_fe_write(mon->chr, (const uint8_t *) buf, len);
-        if (rc == len) {
-            /* all flushed */
+        if ((rc < 0 && errno != EAGAIN) || (rc == len)) {
+            /* all flushed or error */
             QDECREF(mon->outbuf);
             mon->outbuf = qstring_new();
             return;
diff --git a/qmp.c b/qmp.c
index 0f46171aad..d0d98e777b 100644
--- a/qmp.c
+++ b/qmp.c
@@ -27,6 +27,7 @@
 #include "qapi/qmp/qobject.h"
 #include "qapi/qmp-input-visitor.h"
 #include "hw/boards.h"
+#include "qom/object_interfaces.h"
 
 NameInfo *qmp_query_name(Error **errp)
 {
@@ -549,15 +550,28 @@ void object_add(const char *type, const char *id, const QDict *qdict,
         for (e = qdict_first(qdict); e; e = qdict_next(qdict, e)) {
             object_property_set(obj, v, e->key, &local_err);
             if (local_err) {
-                error_propagate(errp, local_err);
-                object_unref(obj);
-                return;
+                goto out;
             }
         }
     }
 
+    if (!object_dynamic_cast(obj, TYPE_USER_CREATABLE)) {
+        error_setg(&local_err, "object '%s' isn't supported by object-add",
+                   id);
+        goto out;
+    }
+
+    user_creatable_complete(obj, &local_err);
+    if (local_err) {
+        goto out;
+    }
+
     object_property_add_child(container_get(object_get_root(), "/objects"),
-                              id, obj, errp);
+                              id, obj, &local_err);
+out:
+    if (local_err) {
+        error_propagate(errp, local_err);
+    }
     object_unref(obj);
 }
 
diff --git a/qom/Makefile.objs b/qom/Makefile.objs
index 6a93ac7398..985003bd03 100644
--- a/qom/Makefile.objs
+++ b/qom/Makefile.objs
@@ -1,2 +1,3 @@
 common-obj-y = object.o container.o qom-qobject.o
 common-obj-y += cpu.o
+common-obj-y += object_interfaces.o
diff --git a/qom/object_interfaces.c b/qom/object_interfaces.c
new file mode 100644
index 0000000000..6360818397
--- /dev/null
+++ b/qom/object_interfaces.c
@@ -0,0 +1,32 @@
+#include "qom/object_interfaces.h"
+#include "qemu/module.h"
+
+void user_creatable_complete(Object *obj, Error **errp)
+{
+
+    UserCreatableClass *ucc;
+    UserCreatable *uc =
+        (UserCreatable *)object_dynamic_cast(obj, TYPE_USER_CREATABLE);
+
+    if (!uc) {
+        return;
+    }
+
+    ucc = USER_CREATABLE_GET_CLASS(uc);
+    if (ucc->complete) {
+        ucc->complete(uc, errp);
+    }
+}
+
+static void register_types(void)
+{
+    static const TypeInfo uc_interface_info = {
+        .name          = TYPE_USER_CREATABLE,
+        .parent        = TYPE_INTERFACE,
+        .class_size = sizeof(UserCreatableClass),
+    };
+
+    type_register_static(&uc_interface_info);
+}
+
+type_init(register_types)
diff --git a/vl.c b/vl.c
index c73462e811..383be1b617 100644
--- a/vl.c
+++ b/vl.c
@@ -170,6 +170,7 @@ int main(int argc, char **argv)
 
 #include "ui/qemu-spice.h"
 #include "qapi/string-input-visitor.h"
+#include "qom/object_interfaces.h"
 
 //#define DEBUG_NET
 //#define DEBUG_SLIRP
@@ -2800,6 +2801,7 @@ static int object_create(QemuOpts *opts, void *opaque)
 {
     const char *type = qemu_opt_get(opts, "qom-type");
     const char *id = qemu_opts_id(opts);
+    Error *local_err = NULL;
     Object *obj;
 
     g_assert(type != NULL);
@@ -2815,9 +2817,27 @@ static int object_create(QemuOpts *opts, void *opaque)
         return -1;
     }
 
+    if (!object_dynamic_cast(obj, TYPE_USER_CREATABLE)) {
+        error_setg(&local_err, "object '%s' isn't supported by -object",
+                   id);
+        goto out;
+    }
+
+    user_creatable_complete(obj, &local_err);
+    if (local_err) {
+        goto out;
+    }
+
     object_property_add_child(container_get(object_get_root(), "/objects"),
-                              id, obj, NULL);
+                              id, obj, &local_err);
+
+out:
     object_unref(obj);
+    if (local_err) {
+        qerror_report_err(local_err);
+        error_free(local_err);
+        return -1;
+    }
     return 0;
 }