--- zzzz-none-000/linux-4.4.271/net/core/rtnetlink.c	2021-06-03 06:22:09.000000000 +0000
+++ hawkeye-5590-750/linux-4.4.271/net/core/rtnetlink.c	2023-04-19 10:22:30.000000000 +0000
@@ -63,6 +63,45 @@
 	rtnl_calcit_func 	calcit;
 };
 
+#if IS_ENABLED(CONFIG_AVM_RTNETLINK_ENHANCEMENT)
+static DECLARE_RWSEM(rtnl_offload_rwsem);
+
+void rtnl_offload_read_lock(void)
+{
+    down_read(&rtnl_offload_rwsem);
+}
+EXPORT_SYMBOL(rtnl_offload_read_lock);
+
+void rtnl_offload_read_unlock(void)
+{
+    up_read(&rtnl_offload_rwsem);
+}
+EXPORT_SYMBOL(rtnl_offload_read_unlock);
+
+
+void rtnl_offload_write_lock(void)
+{
+    down_write(&rtnl_offload_rwsem);
+}
+EXPORT_SYMBOL(rtnl_offload_write_lock);
+
+void rtnl_offload_write_unlock(void)
+{
+    up_write(&rtnl_offload_rwsem);
+}
+EXPORT_SYMBOL(rtnl_offload_write_unlock);
+
+void (*wait_for_link_to_offload_cpu_hook)(void) = NULL;
+EXPORT_SYMBOL(wait_for_link_to_offload_cpu_hook);
+
+void wait_for_link_to_offload_cpu(void){
+   if(wait_for_link_to_offload_cpu_hook != NULL)
+      wait_for_link_to_offload_cpu_hook();
+}
+#endif /* CONFIG_AVM_RTNETLINK_ENHANCEMENT */
+
+// ---------------------------------
+
 static DEFINE_MUTEX(rtnl_mutex);
 
 void rtnl_lock(void)
@@ -2949,7 +2988,7 @@
 	int err;
 
 	if (dev->type != ARPHRD_ETHER)
-		return -EINVAL;
+		return idx;
 
 	netif_addr_lock_bh(dev);
 	err = nlmsg_populate_fdb(skb, cb, dev, &idx, &dev->uc);