softmmu: Fix dirtylimit memory leak

Fix memory leak in hmp_info_vcpu_dirty_limit,use g_autoptr
to handle memory deallocation.

Signed-off-by: alloc.young <alloc.young@outlook.com>
Reviewed-by: Hyman Huang <yong.huang@smartx.com>
Message-Id: <SA1PR11MB6760B9AB7EAFBDAFB524ED06F5E3A@SA1PR11MB6760.namprd11.prod.outlook.com>
Signed-off-by: Hyman Huang <yong.huang@smartx.com>

softmmu/dirtylimit.c

@@ -653,28 +653,26 @@ struct DirtyLimitInfoList *qmp_query_vcpu_dirty_limit(Error **errp)
 
 void hmp_info_vcpu_dirty_limit(Monitor *mon, const QDict *qdict)
 {
-    DirtyLimitInfoList *limit, *head, *info = NULL;
+    DirtyLimitInfoList *info;
+    g_autoptr(DirtyLimitInfoList) head = NULL;
     Error *err = NULL;
 
     if (!dirtylimit_in_service()) {
         monitor_printf(mon, "Dirty page limit not enabled!\n");
         return;
     }
 
-    info = qmp_query_vcpu_dirty_limit(&err);
+    head = qmp_query_vcpu_dirty_limit(&err);
     if (err) {
         hmp_handle_error(mon, err);
         return;
     }
 
-    head = info;
-    for (limit = head; limit != NULL; limit = limit->next) {
+    for (info = head; info != NULL; info = info->next) {
         monitor_printf(mon, "vcpu[%"PRIi64"], limit rate %"PRIi64 " (MB/s),"
                             " current rate %"PRIi64 " (MB/s)\n",
-                            limit->value->cpu_index,
-                            limit->value->limit_rate,
-                            limit->value->current_rate);
+                            info->value->cpu_index,
+                            info->value->limit_rate,
+                            info->value->current_rate);
     }
-
-    g_free(info);
 }