qdev: Use GList for global properties

If the same GlobalProperty struct is registered twice, the list
entry gets corrupted, making tqe_next points to itself, and
qdev_prop_set_globals() gets stuck in a loop. The bug can be
easily reproduced by running:

  $ qemu-system-x86_64 -rtc-td-hack -rtc-td-hack

Change global_props to use GList instead of queue.h, making the
code simpler and able to deal with properties being registered
twice.

Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>

hw/core/qdev-properties.c

@@ -1020,12 +1020,11 @@ void qdev_prop_set_ptr(DeviceState *dev, const char *name, void *value)
     *ptr = value;
 }
 
-static QTAILQ_HEAD(, GlobalProperty) global_props =
-        QTAILQ_HEAD_INITIALIZER(global_props);
+static GList *global_props;
 
 void qdev_prop_register_global(GlobalProperty *prop)
 {
-    QTAILQ_INSERT_TAIL(&global_props, prop, next);
+    global_props = g_list_append(global_props, prop);
 }
 
 void qdev_prop_register_global_list(GlobalProperty *props)
@@ -1039,10 +1038,11 @@ void qdev_prop_register_global_list(GlobalProperty *props)
 
 int qdev_prop_check_globals(void)
 {
-    GlobalProperty *prop;
+    GList *l;
     int ret = 0;
 
-    QTAILQ_FOREACH(prop, &global_props, next) {
+    for (l = global_props; l; l = l->next) {
+        GlobalProperty *prop = l->data;
         ObjectClass *oc;
         DeviceClass *dc;
         if (prop->used) {
@@ -1073,9 +1073,10 @@ int qdev_prop_check_globals(void)
 static void qdev_prop_set_globals_for_type(DeviceState *dev,
                                 const char *typename)
 {
-    GlobalProperty *prop;
+    GList *l;
 
-    QTAILQ_FOREACH(prop, &global_props, next) {
+    for (l = global_props; l; l = l->next) {
+        GlobalProperty *prop = l->data;
         Error *err = NULL;
 
         if (strcmp(typename, prop->driver) != 0) {

include/hw/qdev-core.h

@@ -266,7 +266,6 @@ typedef struct GlobalProperty {
     const char *value;
     bool user_provided;
     bool used;
-    QTAILQ_ENTRY(GlobalProperty) next;
 } GlobalProperty;
 
 /*** Board API.  This should go away once we have a machine config file.  ***/