* tp_input() gets an mbuf chain from ip. Actually, not directly
* from ip, because ip calls a net-level routine that strips off
* the net header and then calls tp_input(), passing the proper type
* tp_input() gets an mbuf chain from ip. Actually, not directly
* from ip, because ip calls a net-level routine that strips off
* the net header and then calls tp_input(), passing the proper type