net_ns_init

Linux 6.18.37 LTS: net/core/net_namespace.c
Linux 6.18.37 LTS: net/core/dev.c
Linux 6.18.37 LTS: include/net/net_namespace.h

void __init net_ns_init(void)
{
	struct net_generic *ng;

#ifdef CONFIG_NET_NS
	netns_ipv4_struct_check();
	net_cachep = kmem_cache_create("net_namespace", sizeof(struct net),
					SMP_CACHE_BYTES,
					SLAB_PANIC|SLAB_ACCOUNT, NULL);

	/* Create workqueue for cleanup */
	netns_wq = create_singlethread_workqueue("netns");
	if (!netns_wq)
		panic("Could not create netns workq");
#endif

	ng = net_alloc_generic();
	if (!ng)
		panic("Could not allocate generic netns");

	rcu_assign_pointer(init_net.gen, ng);

#ifdef CONFIG_KEYS
	init_net.key_domain = &init_net_key_domain;
#endif
	/*
	 * This currently cannot fail as the initial network namespace
	 * has a static inode number.
	 */
	if (preinit_net(&init_net, &init_user_ns))
		panic("Could not preinitialize the initial network namespace");

	down_write(&pernet_ops_rwsem);
	if (setup_net(&init_net))
		panic("Could not setup the initial network namespace");

	init_net_initialized = true;
	up_write(&pernet_ops_rwsem);

	if (register_pernet_subsys(&net_ns_ops))
		panic("Could not register network namespace subsystems");

	rtnl_register_many(net_ns_rtnl_msg_handlers);
}

static __net_init int setup_net(struct net *net)
{
	/* Must be called with pernet_ops_rwsem held */
	const struct pernet_operations *ops;
	LIST_HEAD(net_exit_list);
	int error = 0;

	net->net_cookie = ns_tree_gen_id(&net->ns);

	list_for_each_entry(ops, &pernet_list, list) {
		error = ops_init(ops, net);
		if (error < 0)
			goto out_undo;
	}
	down_write(&net_rwsem);
	list_add_tail_rcu(&net->list, &net_namespace_list);
	up_write(&net_rwsem);
	ns_tree_add_raw(net);
out:
	return error;

out_undo:
	/* Walk through the list backwards calling the exit functions
	 * for the pernet modules whose init functions did not fail.
	 */
	list_add(&net->exit_list, &net_exit_list);
	ops_undo_list(&pernet_list, ops, &net_exit_list, false);
	rcu_barrier();
	goto out;
}