From 98565127c60cba3d5b747bb9eb698e06d187f45b Mon Sep 17 00:00:00 2001
From: Felix Fietkau <nbd@openwrt.org>
Date: Sun, 2 Oct 2011 19:32:44 +0200
Subject: [PATCH] extend vlist code to allow keeping the old data structure
 instead of the new one on updates

---
 utils.c | 5 +++++
 utils.h | 1 +
 2 files changed, 6 insertions(+)

diff --git a/utils.c b/utils.c
index 42d3176..a67a8c9 100644
--- a/utils.c
+++ b/utils.c
@@ -37,11 +37,16 @@ vlist_add(struct vlist_tree *tree, struct vlist_node *node)
 
 	anode = avl_find(&tree->avl, key);
 	if (anode) {
+		if (tree->keep_old)
+			goto update_only;
+
 		old_node = container_of(anode, struct vlist_node, avl);
 		avl_delete(&tree->avl, anode);
 	}
 
 	avl_insert(&tree->avl, &node->avl);
+
+update_only:
 	tree->update(tree, node, old_node);
 }
 
diff --git a/utils.h b/utils.h
index c8101e7..ab73930 100644
--- a/utils.h
+++ b/utils.h
@@ -28,6 +28,7 @@ struct vlist_tree {
 
 	vlist_update_cb update;
 	int node_offset;
+	bool keep_old;
 
 	int version;
 };
-- 
2.25.1