item_tag_set
item_tag_set(&tree, start, 0);
item_tag_set(&tree, start-1, 0);
item_tag_set(&tree, end, 0);
item_tag_set(&tree, end+1, 0);
item_tag_set(&tree, idx[i], 0);
item_tag_set(&tree, tmp+1, 0);
item_tag_set(tree, index, tag);
item_tag_set(tree, index, tag);
item_tag_set(tree, index, tag);
item_tag_set(&tree, 0, 0);
item_tag_set(&tree, 43, 0);
item_tag_set(&tree, 0, 0);
item_tag_set(&tree, tmp, 0);
item_tag_set(&tree, tmp, 1);
item_tag_set(struct radix_tree_root *root, unsigned long index, int tag);