一、kernel中PF_PACKET协议族注册

af_packet.c

module_init(packet_init);

static int __init packet_init(void)
{
	int rc = proto_register(&packet_proto, 0);

	if (rc != 0)
		goto out;

	sock_register(&packet_family_ops);
	register_pernet_subsys(&packet_net_ops);
	register_netdevice_notifier(&packet_netdev_notifier);
out:
	return rc;
}

1. 将协议族入口注册到全局数组中

static const struct net_proto_family packet_family_ops = {
	.family =	PF_PACKET,
	.create =	packet_create,
	.owner	=	THIS_MODULE,
};

sock_register(&packet_family_ops);

// net/socket.c
int sock_register(const struct net_proto_family *ops)
{
	...
		rcu_assign_pointer(net_families[ops->family], ops);
	...
}