ipv6: remove ipv6_stub infrastructure completely

As IPv6 is built-in only and there are no more users of ipv6_stub, the
ipv6_stub is now entirely obsolete.

Remove all the code related to the definition, initialization and usage.

Signed-off-by: Fernando Fernandez Mancera <fmancera@suse.de>
Tested-by: Ricardo B. Marlière <rbm@suse.com>
Link: https://patch.msgid.link/20260325120928.15848-11-fmancera@suse.de
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

4 files changed, 1 insertions, 141 deletions

diff --git a/net/ipv6/addrconf_core.c b/net/ipv6/addrconf_core.c
index c008d21925d7..fa27a90ab3cd 100644
--- a/net/ipv6/addrconf_core.c
+++ b/net/ipv6/addrconf_core.c
@@ -6,7 +6,6 @@
 
 #include <linux/export.h>
 #include <net/ipv6.h>
-#include <net/ipv6_stubs.h>
 #include <net/addrconf.h>
 #include <net/ip.h>
 
@@ -129,96 +128,6 @@ int inet6addr_validator_notifier_call_chain(unsigned long val, void *v)
 }
 EXPORT_SYMBOL(inet6addr_validator_notifier_call_chain);
 
-static struct dst_entry *eafnosupport_ipv6_dst_lookup_flow(struct net *net,
-							   const struct sock *sk,
-							   struct flowi6 *fl6,
-							   const struct in6_addr *final_dst)
-{
-	return ERR_PTR(-EAFNOSUPPORT);
-}
-
-static int eafnosupport_ipv6_route_input(struct sk_buff *skb)
-{
-	return -EAFNOSUPPORT;
-}
-
-static struct fib6_table *eafnosupport_fib6_get_table(struct net *net, u32 id)
-{
-	return NULL;
-}
-
-static int
-eafnosupport_fib6_table_lookup(struct net *net, struct fib6_table *table,
-			       int oif, struct flowi6 *fl6,
-			       struct fib6_result *res, int flags)
-{
-	return -EAFNOSUPPORT;
-}
-
-static int
-eafnosupport_fib6_lookup(struct net *net, int oif, struct flowi6 *fl6,
-			 struct fib6_result *res, int flags)
-{
-	return -EAFNOSUPPORT;
-}
-
-static void
-eafnosupport_fib6_select_path(const struct net *net, struct fib6_result *res,
-			      struct flowi6 *fl6, int oif, bool have_oif_match,
-			      const struct sk_buff *skb, int strict)
-{
-}
-
-static u32
-eafnosupport_ip6_mtu_from_fib6(const struct fib6_result *res,
-			       const struct in6_addr *daddr,
-			       const struct in6_addr *saddr)
-{
-	return 0;
-}
-
-static int eafnosupport_fib6_nh_init(struct net *net, struct fib6_nh *fib6_nh,
-				     struct fib6_config *cfg, gfp_t gfp_flags,
-				     struct netlink_ext_ack *extack)
-{
-	NL_SET_ERR_MSG(extack, "IPv6 support not enabled in kernel");
-	return -EAFNOSUPPORT;
-}
-
-static int eafnosupport_ip6_del_rt(struct net *net, struct fib6_info *rt,
-				   bool skip_notify)
-{
-	return -EAFNOSUPPORT;
-}
-
-static int eafnosupport_ipv6_fragment(struct net *net, struct sock *sk, struct sk_buff *skb,
-				      int (*output)(struct net *, struct sock *, struct sk_buff *))
-{
-	kfree_skb(skb);
-	return -EAFNOSUPPORT;
-}
-
-static struct net_device *eafnosupport_ipv6_dev_find(struct net *net, const struct in6_addr *addr,
-						     struct net_device *dev)
-{
-	return ERR_PTR(-EAFNOSUPPORT);
-}
-
-const struct ipv6_stub *ipv6_stub __read_mostly = &(struct ipv6_stub) {
-	.ipv6_dst_lookup_flow = eafnosupport_ipv6_dst_lookup_flow,
-	.ipv6_route_input  = eafnosupport_ipv6_route_input,
-	.fib6_get_table    = eafnosupport_fib6_get_table,
-	.fib6_table_lookup = eafnosupport_fib6_table_lookup,
-	.fib6_lookup       = eafnosupport_fib6_lookup,
-	.fib6_select_path  = eafnosupport_fib6_select_path,
-	.ip6_mtu_from_fib6 = eafnosupport_ip6_mtu_from_fib6,
-	.fib6_nh_init	   = eafnosupport_fib6_nh_init,
-	.ip6_del_rt	   = eafnosupport_ip6_del_rt,
-	.ipv6_fragment	   = eafnosupport_ipv6_fragment,
-	.ipv6_dev_find     = eafnosupport_ipv6_dev_find,
-};
-EXPORT_SYMBOL_GPL(ipv6_stub);
-
 /* IPv6 Wildcard Address and Loopback Address defined by RFC2553 */
 const struct in6_addr in6addr_loopback __aligned(BITS_PER_LONG/8)
 	= IN6ADDR_LOOPBACK_INIT;
diff --git a/net/ipv6/af_inet6.c b/net/ipv6/af_inet6.c
index 07ae6ea7743a..33abd8d8cd7d 100644
--- a/net/ipv6/af_inet6.c
+++ b/net/ipv6/af_inet6.c
@@ -51,7 +51,6 @@
 #include <net/transp_v6.h>
 #include <net/ip6_route.h>
 #include <net/addrconf.h>
-#include <net/ipv6_stubs.h>
 #include <net/ndisc.h>
 #ifdef CONFIG_IPV6_TUNNEL
 #include <net/ip6_tunnel.h>
@@ -996,42 +995,6 @@ static struct pernet_operations inet6_net_ops = {
 	.exit = inet6_net_exit,
 };
 
-static int ipv6_route_input(struct sk_buff *skb)
-{
-	ip6_route_input(skb);
-	return skb_dst(skb)->error;
-}
-
-static const struct ipv6_stub ipv6_stub_impl = {
-	.ipv6_sock_mc_join = ipv6_sock_mc_join,
-	.ipv6_sock_mc_drop = ipv6_sock_mc_drop,
-	.ipv6_dst_lookup_flow = ip6_dst_lookup_flow,
-	.ipv6_route_input  = ipv6_route_input,
-	.fib6_get_table	   = fib6_get_table,
-	.fib6_table_lookup = fib6_table_lookup,
-	.fib6_lookup       = fib6_lookup,
-	.fib6_select_path  = fib6_select_path,
-	.ip6_mtu_from_fib6 = ip6_mtu_from_fib6,
-	.fib6_nh_init	   = fib6_nh_init,
-	.fib6_nh_release   = fib6_nh_release,
-	.fib6_nh_release_dsts = fib6_nh_release_dsts,
-	.fib6_update_sernum = fib6_update_sernum_stub,
-	.fib6_rt_update	   = fib6_rt_update,
-	.ip6_del_rt	   = ip6_del_rt,
-	.udpv6_encap_enable = udpv6_encap_enable,
-	.ndisc_send_na = ndisc_send_na,
-#if IS_ENABLED(CONFIG_XFRM)
-	.xfrm6_local_rxpmtu = xfrm6_local_rxpmtu,
-	.xfrm6_udp_encap_rcv = xfrm6_udp_encap_rcv,
-	.xfrm6_gro_udp_encap_rcv = xfrm6_gro_udp_encap_rcv,
-	.xfrm6_rcv_encap = xfrm6_rcv_encap,
-#endif
-	.nd_tbl	= &nd_tbl,
-	.ipv6_fragment = ip6_fragment,
-	.ipv6_dev_find = ipv6_dev_find,
-	.ip6_xmit = ip6_xmit,
-};
-
 static int __init inet6_init(void)
 {
 	struct list_head *r;
@@ -1188,9 +1151,6 @@ static int __init inet6_init(void)
 		goto sysctl_fail;
 #endif
 
-	/* ensure that ipv6 stubs are visible only after ipv6 is ready */
-	wmb();
-	ipv6_stub = &ipv6_stub_impl;
 out:
 	return err;
 
diff --git a/net/ipv6/ip6_fib.c b/net/ipv6/ip6_fib.c
index 17f757e9c54a..0691f561bc26 100644
--- a/net/ipv6/ip6_fib.c
+++ b/net/ipv6/ip6_fib.c
@@ -1408,14 +1408,6 @@ void fib6_update_sernum_upto_root(struct net *net, struct fib6_info *rt)
 	__fib6_update_sernum_upto_root(rt, fib6_new_sernum(net));
 }
 
-/* allow ipv4 to update sernum via ipv6_stub */
-void fib6_update_sernum_stub(struct net *net, struct fib6_info *f6i)
-{
-	spin_lock_bh(&f6i->fib6_table->tb6_lock);
-	fib6_update_sernum_upto_root(net, f6i);
-	spin_unlock_bh(&f6i->fib6_table->tb6_lock);
-}
-
 /*
  *	Add routing information to the routing tree.
  *	<destination addr>/<source addr>
diff --git a/net/ipv6/ip6_udp_tunnel.c b/net/ipv6/ip6_udp_tunnel.c
index cef3e0210744..405ef1cb8864 100644
--- a/net/ipv6/ip6_udp_tunnel.c
+++ b/net/ipv6/ip6_udp_tunnel.c
@@ -162,8 +162,7 @@ struct dst_entry *udp_tunnel6_dst_lookup(struct sk_buff *skb,
 	fl6.fl6_dport = dport;
 	fl6.flowlabel = ip6_make_flowinfo(dsfield, key->label);
 
-	dst = ipv6_stub->ipv6_dst_lookup_flow(net, sock->sk, &fl6,
-					      NULL);
+	dst = ip6_dst_lookup_flow(net, sock->sk, &fl6, NULL);
 	if (IS_ERR(dst)) {
 		netdev_dbg(dev, "no route to %pI6\n", &fl6.daddr);
 		return ERR_PTR(-ENETUNREACH);