* The new node will become the first node and
* new_node->next will be the previous first node
*/
new_node->next = tmp_node;
new_node->prev = NULL;
tmp_node->prev = new_node;
* The new node will become the first node and
* new_node->next will be the previous first node
*/
new_node->next = tmp_node;
new_node->prev = NULL;
tmp_node->prev = new_node;