Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next

Pull networking updates from David Miller:

 1) Support 6Ghz band in ath11k driver, from Rajkumar Manoharan.

 2) Support UDP segmentation in code TSO code, from Eric Dumazet.

 3) Allow flashing different flash images in cxgb4 driver, from Vishal
    Kulkarni.

 4) Add drop frames counter and flow status to tc flower offloading,
    from Po Liu.

 5) Support n-tuple filters in cxgb4, from Vishal Kulkarni.

 6) Various new indirect call avoidance, from Eric Dumazet and Brian
    Vazquez.

 7) Fix BPF verifier failures on 32-bit pointer arithmetic, from
    Yonghong Song.

 8) Support querying and setting hardware address of a port function via
    devlink, use this in mlx5, from Parav Pandit.

 9) Support hw ipsec offload on bonding slaves, from Jarod Wilson.

10) Switch qca8k driver over to phylink, from Jonathan McDowell.

11) In bpftool, show list of processes holding BPF FD references to
    maps, programs, links, and btf objects. From Andrii Nakryiko.

12) Several conversions over to generic power management, from Vaibhav
    Gupta.

13) Add support for SO_KEEPALIVE et al. to bpf_setsockopt(), from Dmitry
    Yakunin.

14) Various https url conversions, from Alexander A. Klimov.

15) Timestamping and PHC support for mscc PHY driver, from Antoine
    Tenart.

16) Support bpf iterating over tcp and udp sockets, from Yonghong Song.

17) Support 5GBASE-T i40e NICs, from Aleksandr Loktionov.

18) Add kTLS RX HW offload support to mlx5e, from Tariq Toukan.

19) Fix the ->ndo_start_xmit() return type to be netdev_tx_t in several
    drivers. From Luc Van Oostenryck.

20) XDP support for xen-netfront, from Denis Kirjanov.

21) Support receive buffer autotuning in MPTCP, from Florian Westphal.

22) Support EF100 chip in sfc driver, from Edward Cree.

23) Add XDP support to mvpp2 driver, from Matteo Croce.

24) Support MPTCP in sock_diag, from Paolo Abeni.

25) Commonize UDP tunnel offloading code by creating udp_tunnel_nic
    infrastructure, from Jakub Kicinski.

26) Several pci_ --> dma_ API conversions, from Christophe JAILLET.

27) Add FLOW_ACTION_POLICE support to mlxsw, from Ido Schimmel.

28) Add SK_LOOKUP bpf program type, from Jakub Sitnicki.

29) Refactor a lot of networking socket option handling code in order to
    avoid set_fs() calls, from Christoph Hellwig.

30) Add rfc4884 support to icmp code, from Willem de Bruijn.

31) Support TBF offload in dpaa2-eth driver, from Ioana Ciornei.

32) Support XDP_REDIRECT in qede driver, from Alexander Lobakin.

33) Support PCI relaxed ordering in mlx5 driver, from Aya Levin.

34) Support TCP syncookies in MPTCP, from Flowian Westphal.

35) Fix several tricky cases of PMTU handling wrt. briding, from Stefano
    Brivio.

* git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next: (2056 commits)
  net: thunderx: initialize VF's mailbox mutex before first usage
  usb: hso: remove bogus check for EINPROGRESS
  usb: hso: no complaint about kmalloc failure
  hso: fix bailout in error case of probe
  ip_tunnel_core: Fix build for archs without _HAVE_ARCH_IPV6_CSUM
  selftests/net: relax cpu affinity requirement in msg_zerocopy test
  mptcp: be careful on subflow creation
  selftests: rtnetlink: make kci_test_encap() return sub-test result
  selftests: rtnetlink: correct the final return value for the test
  net: dsa: sja1105: use detected device id instead of DT one on mismatch
  tipc: set ub->ifindex for local ipv6 address
  ipv6: add ipv6_dev_find()
  net: openvswitch: silence suspicious RCU usage warning
  Revert "vxlan: fix tos value before xmit"
  ptp: only allow phase values lower than 1 period
  farsync: switch from 'pci_' to 'dma_' API
  wan: wanxl: switch from 'pci_' to 'dma_' API
  hv_netvsc: do not use VF device if link is down
  dpaa2-eth: Fix passing zero to 'PTR_ERR' warning
  net: macb: Properly handle phylink on at91sam9x
  ...

8 files changed, 489 insertions, 458 deletions

diff --git a/net/l2tp/l2tp_core.c b/net/l2tp/l2tp_core.c
index 6434d17e6e8e..701fc72ad9f4 100644
--- a/net/l2tp/l2tp_core.c
+++ b/net/l2tp/l2tp_core.c
@@ -1,6 +1,5 @@
 // SPDX-License-Identifier: GPL-2.0-only
-/*
- * L2TP core.
+/* L2TP core.
  *
  * Copyright (c) 2008,2009,2010 Katalix Systems Ltd
  *
@@ -94,7 +93,7 @@ struct l2tp_skb_cb {
 	unsigned long		expires;
 };
 
-#define L2TP_SKB_CB(skb)	((struct l2tp_skb_cb *) &skb->cb[sizeof(struct inet_skb_parm)])
+#define L2TP_SKB_CB(skb)	((struct l2tp_skb_cb *)&(skb)->cb[sizeof(struct inet_skb_parm)])
 
 static struct workqueue_struct *l2tp_wq;
 
@@ -102,8 +101,10 @@ static struct workqueue_struct *l2tp_wq;
 static unsigned int l2tp_net_id;
 struct l2tp_net {
 	struct list_head l2tp_tunnel_list;
+	/* Lock for write access to l2tp_tunnel_list */
 	spinlock_t l2tp_tunnel_list_lock;
 	struct hlist_head l2tp_session_hlist[L2TP_HASH_SIZE_2];
+	/* Lock for write access to l2tp_session_hlist */
 	spinlock_t l2tp_session_hlist_lock;
 };
 
@@ -134,7 +135,6 @@ static inline struct hlist_head *
 l2tp_session_id_hash_2(struct l2tp_net *pn, u32 session_id)
 {
 	return &pn->l2tp_session_hlist[hash_32(session_id, L2TP_HASH_BITS_2)];
-
 }
 
 /* Session hash list.
@@ -149,12 +149,51 @@ l2tp_session_id_hash(struct l2tp_tunnel *tunnel, u32 session_id)
 	return &tunnel->session_hlist[hash_32(session_id, L2TP_HASH_BITS)];
 }
 
-void l2tp_tunnel_free(struct l2tp_tunnel *tunnel)
+static void l2tp_tunnel_free(struct l2tp_tunnel *tunnel)
 {
 	sock_put(tunnel->sock);
 	/* the tunnel is freed in the socket destructor */
 }
-EXPORT_SYMBOL(l2tp_tunnel_free);
+
+static void l2tp_session_free(struct l2tp_session *session)
+{
+	struct l2tp_tunnel *tunnel = session->tunnel;
+
+	if (tunnel) {
+		if (WARN_ON(tunnel->magic != L2TP_TUNNEL_MAGIC))
+			goto out;
+		l2tp_tunnel_dec_refcount(tunnel);
+	}
+
+out:
+	kfree(session);
+}
+
+void l2tp_tunnel_inc_refcount(struct l2tp_tunnel *tunnel)
+{
+	refcount_inc(&tunnel->ref_count);
+}
+EXPORT_SYMBOL_GPL(l2tp_tunnel_inc_refcount);
+
+void l2tp_tunnel_dec_refcount(struct l2tp_tunnel *tunnel)
+{
+	if (refcount_dec_and_test(&tunnel->ref_count))
+		l2tp_tunnel_free(tunnel);
+}
+EXPORT_SYMBOL_GPL(l2tp_tunnel_dec_refcount);
+
+void l2tp_session_inc_refcount(struct l2tp_session *session)
+{
+	refcount_inc(&session->ref_count);
+}
+EXPORT_SYMBOL_GPL(l2tp_session_inc_refcount);
+
+void l2tp_session_dec_refcount(struct l2tp_session *session)
+{
+	if (refcount_dec_and_test(&session->ref_count))
+		l2tp_session_free(session);
+}
+EXPORT_SYMBOL_GPL(l2tp_session_dec_refcount);
 
 /* Lookup a tunnel. A new reference is held on the returned tunnel. */
 struct l2tp_tunnel *l2tp_tunnel_get(const struct net *net, u32 tunnel_id)
@@ -412,7 +451,7 @@ static void l2tp_recv_dequeue_skb(struct l2tp_session *session, struct sk_buff *
 	}
 
 	/* call private receive handler */
-	if (session->recv_skb != NULL)
+	if (session->recv_skb)
 		(*session->recv_skb)(session, skb, L2TP_SKB_CB(skb)->length);
 	else
 		kfree_skb(skb);
@@ -621,8 +660,8 @@ void l2tp_recv_common(struct l2tp_session *session, struct sk_buff *skb,
 		      int length)
 {
 	struct l2tp_tunnel *tunnel = session->tunnel;
+	u32 ns = 0, nr = 0;
 	int offset;
-	u32 ns, nr;
 
 	/* Parse and check optional cookie */
 	if (session->peer_cookie_len > 0) {
@@ -644,13 +683,12 @@ void l2tp_recv_common(struct l2tp_session *session, struct sk_buff *skb,
 	 * the control of the LNS.  If no sequence numbers present but
 	 * we were expecting them, discard frame.
 	 */
-	ns = nr = 0;
 	L2TP_SKB_CB(skb)->has_seq = 0;
 	if (tunnel->version == L2TP_HDR_VER_2) {
 		if (hdrflags & L2TP_HDRFLAG_S) {
-			ns = ntohs(*(__be16 *) ptr);
+			ns = ntohs(*(__be16 *)ptr);
 			ptr += 2;
-			nr = ntohs(*(__be16 *) ptr);
+			nr = ntohs(*(__be16 *)ptr);
 			ptr += 2;
 
 			/* Store L2TP info in the skb */
@@ -662,7 +700,7 @@ void l2tp_recv_common(struct l2tp_session *session, struct sk_buff *skb,
 				 session->name, ns, nr, session->nr);
 		}
 	} else if (session->l2specific_type == L2TP_L2SPECTYPE_DEFAULT) {
-		u32 l2h = ntohl(*(__be32 *) ptr);
+		u32 l2h = ntohl(*(__be32 *)ptr);
 
 		if (l2h & 0x40000000) {
 			ns = l2h & 0x00ffffff;
@@ -679,11 +717,11 @@ void l2tp_recv_common(struct l2tp_session *session, struct sk_buff *skb,
 	}
 
 	if (L2TP_SKB_CB(skb)->has_seq) {
-		/* Received a packet with sequence numbers. If we're the LNS,
+		/* Received a packet with sequence numbers. If we're the LAC,
 		 * check if we sre sending sequence numbers and if not,
 		 * configure it so.
 		 */
-		if ((!session->lns_mode) && (!session->send_seq)) {
+		if (!session->lns_mode && !session->send_seq) {
 			l2tp_info(session, L2TP_MSG_SEQ,
 				  "%s: requested to enable seq numbers by LNS\n",
 				  session->name);
@@ -707,7 +745,7 @@ void l2tp_recv_common(struct l2tp_session *session, struct sk_buff *skb,
 		 * If we're the LNS and we're sending sequence numbers, the
 		 * LAC is broken. Discard the frame.
 		 */
-		if ((!session->lns_mode) && (session->send_seq)) {
+		if (!session->lns_mode && session->send_seq) {
 			l2tp_info(session, L2TP_MSG_SEQ,
 				  "%s: requested to disable seq numbers by LNS\n",
 				  session->name);
@@ -770,20 +808,21 @@ discard:
 	atomic_long_inc(&session->stats.rx_errors);
 	kfree_skb(skb);
 }
-EXPORT_SYMBOL(l2tp_recv_common);
+EXPORT_SYMBOL_GPL(l2tp_recv_common);
 
 /* Drop skbs from the session's reorder_q
  */
-static int l2tp_session_queue_purge(struct l2tp_session *session)
+static void l2tp_session_queue_purge(struct l2tp_session *session)
 {
 	struct sk_buff *skb = NULL;
-	BUG_ON(!session);
-	BUG_ON(session->magic != L2TP_SESSION_MAGIC);
+
+	if (WARN_ON(session->magic != L2TP_SESSION_MAGIC))
+		return;
+
 	while ((skb = skb_dequeue(&session->reorder_q))) {
 		atomic_long_inc(&session->stats.rx_errors);
 		kfree_skb(skb);
 	}
-	return 0;
 }
 
 /* Internal UDP receive frame. Do the real work of receiving an L2TP data frame
@@ -825,10 +864,11 @@ static int l2tp_udp_recv_core(struct l2tp_tunnel *tunnel, struct sk_buff *skb)
 	}
 
 	/* Point to L2TP header */
-	optr = ptr = skb->data;
+	optr = skb->data;
+	ptr = skb->data;
 
 	/* Get L2TP header flags */
-	hdrflags = ntohs(*(__be16 *) ptr);
+	hdrflags = ntohs(*(__be16 *)ptr);
 
 	/* Check protocol version */
 	version = hdrflags & L2TP_HDR_VER_MASK;
@@ -859,14 +899,14 @@ static int l2tp_udp_recv_core(struct l2tp_tunnel *tunnel, struct sk_buff *skb)
 			ptr += 2;
 
 		/* Extract tunnel and session ID */
-		tunnel_id = ntohs(*(__be16 *) ptr);
+		tunnel_id = ntohs(*(__be16 *)ptr);
 		ptr += 2;
-		session_id = ntohs(*(__be16 *) ptr);
+		session_id = ntohs(*(__be16 *)ptr);
 		ptr += 2;
 	} else {
 		ptr += 2;	/* skip reserved bits */
 		tunnel_id = tunnel->tunnel_id;
-		session_id = ntohl(*(__be32 *) ptr);
+		session_id = ntohl(*(__be32 *)ptr);
 		ptr += 4;
 	}
 
@@ -910,7 +950,7 @@ int l2tp_udp_encap_recv(struct sock *sk, struct sk_buff *skb)
 	struct l2tp_tunnel *tunnel;
 
 	tunnel = rcu_dereference_sk_user_data(sk);
-	if (tunnel == NULL)
+	if (!tunnel)
 		goto pass_up;
 
 	l2tp_dbg(tunnel, L2TP_MSG_DATA, "%s: received %d bytes\n",
@@ -971,13 +1011,13 @@ static int l2tp_build_l2tpv3_header(struct l2tp_session *session, void *buf)
 	 */
 	if (tunnel->encap == L2TP_ENCAPTYPE_UDP) {
 		u16 flags = L2TP_HDR_VER_3;
-		*((__be16 *) bufp) = htons(flags);
+		*((__be16 *)bufp) = htons(flags);
 		bufp += 2;
-		*((__be16 *) bufp) = 0;
+		*((__be16 *)bufp) = 0;
 		bufp += 2;
 	}
 
-	*((__be32 *) bufp) = htonl(session->peer_session_id);
+	*((__be32 *)bufp) = htonl(session->peer_session_id);
 	bufp += 4;
 	if (session->cookie_len) {
 		memcpy(bufp, &session->cookie[0], session->cookie_len);
@@ -1076,7 +1116,10 @@ int l2tp_xmit_skb(struct l2tp_session *session, struct sk_buff *skb, int hdr_len
 	}
 
 	/* Setup L2TP header */
-	session->build_header(session, __skb_push(skb, hdr_len));
+	if (tunnel->version == L2TP_HDR_VER_2)
+		l2tp_build_l2tpv2_header(session, __skb_push(skb, hdr_len));
+	else
+		l2tp_build_l2tpv3_header(session, __skb_push(skb, hdr_len));
 
 	/* Reset skb netfilter state */
 	memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
@@ -1121,8 +1164,8 @@ int l2tp_xmit_skb(struct l2tp_session *session, struct sk_buff *skb, int hdr_len
 				      &sk->sk_v6_daddr, udp_len);
 		else
 #endif
-		udp_set_csum(sk->sk_no_check_tx, skb, inet->inet_saddr,
-			     inet->inet_daddr, udp_len);
+			udp_set_csum(sk->sk_no_check_tx, skb, inet->inet_saddr,
+				     inet->inet_daddr, udp_len);
 		break;
 
 	case L2TP_ENCAPTYPE_IP:
@@ -1149,7 +1192,7 @@ static void l2tp_tunnel_destruct(struct sock *sk)
 {
 	struct l2tp_tunnel *tunnel = l2tp_tunnel(sk);
 
-	if (tunnel == NULL)
+	if (!tunnel)
 		goto end;
 
 	l2tp_info(tunnel, L2TP_MSG_CONTROL, "%s: closing...\n", tunnel->name);
@@ -1179,6 +1222,30 @@ end:
 	return;
 }
 
+/* Remove an l2tp session from l2tp_core's hash lists. */
+static void l2tp_session_unhash(struct l2tp_session *session)
+{
+	struct l2tp_tunnel *tunnel = session->tunnel;
+
+	/* Remove the session from core hashes */
+	if (tunnel) {
+		/* Remove from the per-tunnel hash */
+		write_lock_bh(&tunnel->hlist_lock);
+		hlist_del_init(&session->hlist);
+		write_unlock_bh(&tunnel->hlist_lock);
+
+		/* For L2TPv3 we have a per-net hash: remove from there, too */
+		if (tunnel->version != L2TP_HDR_VER_2) {
+			struct l2tp_net *pn = l2tp_pernet(tunnel->l2tp_net);
+
+			spin_lock_bh(&pn->l2tp_session_hlist_lock);
+			hlist_del_init_rcu(&session->global_hlist);
+			spin_unlock_bh(&pn->l2tp_session_hlist_lock);
+			synchronize_rcu();
+		}
+	}
+}
+
 /* When the tunnel is closed, all the attached sessions need to go too.
  */
 static void l2tp_tunnel_closeall(struct l2tp_tunnel *tunnel)
@@ -1188,8 +1255,6 @@ static void l2tp_tunnel_closeall(struct l2tp_tunnel *tunnel)
 	struct hlist_node *tmp;
 	struct l2tp_session *session;
 
-	BUG_ON(tunnel == NULL);
-
 	l2tp_info(tunnel, L2TP_MSG_CONTROL, "%s: closing all sessions...\n",
 		  tunnel->name);
 
@@ -1210,10 +1275,10 @@ again:
 
 			write_unlock_bh(&tunnel->hlist_lock);
 
-			__l2tp_session_unhash(session);
+			l2tp_session_unhash(session);
 			l2tp_session_queue_purge(session);
 
-			if (session->session_close != NULL)
+			if (session->session_close)
 				(*session->session_close)(session);
 
 			l2tp_session_dec_refcount(session);
@@ -1284,10 +1349,10 @@ static void l2tp_tunnel_del_work(struct work_struct *work)
  * exit hook.
  */
 static int l2tp_tunnel_sock_create(struct net *net,
-				u32 tunnel_id,
-				u32 peer_tunnel_id,
-				struct l2tp_tunnel_cfg *cfg,
-				struct socket **sockp)
+				   u32 tunnel_id,
+				   u32 peer_tunnel_id,
+				   struct l2tp_tunnel_cfg *cfg,
+				   struct socket **sockp)
 {
 	int err = -EINVAL;
 	struct socket *sock = NULL;
@@ -1305,9 +1370,9 @@ static int l2tp_tunnel_sock_create(struct net *net,
 			memcpy(&udp_conf.peer_ip6, cfg->peer_ip6,
 			       sizeof(udp_conf.peer_ip6));
 			udp_conf.use_udp6_tx_checksums =
-			  ! cfg->udp6_zero_tx_checksums;
+			  !cfg->udp6_zero_tx_checksums;
 			udp_conf.use_udp6_rx_checksums =
-			  ! cfg->udp6_zero_rx_checksums;
+			  !cfg->udp6_zero_rx_checksums;
 		} else
 #endif
 		{
@@ -1332,7 +1397,7 @@ static int l2tp_tunnel_sock_create(struct net *net,
 			struct sockaddr_l2tpip6 ip6_addr = {0};
 
 			err = sock_create_kern(net, AF_INET6, SOCK_DGRAM,
-					  IPPROTO_L2TP, &sock);
+					       IPPROTO_L2TP, &sock);
 			if (err < 0)
 				goto out;
 
@@ -1340,7 +1405,7 @@ static int l2tp_tunnel_sock_create(struct net *net,
 			memcpy(&ip6_addr.l2tp_addr, cfg->local_ip6,
 			       sizeof(ip6_addr.l2tp_addr));
 			ip6_addr.l2tp_conn_id = tunnel_id;
-			err = kernel_bind(sock, (struct sockaddr *) &ip6_addr,
+			err = kernel_bind(sock, (struct sockaddr *)&ip6_addr,
 					  sizeof(ip6_addr));
 			if (err < 0)
 				goto out;
@@ -1350,7 +1415,7 @@ static int l2tp_tunnel_sock_create(struct net *net,
 			       sizeof(ip6_addr.l2tp_addr));
 			ip6_addr.l2tp_conn_id = peer_tunnel_id;
 			err = kernel_connect(sock,
-					     (struct sockaddr *) &ip6_addr,
+					     (struct sockaddr *)&ip6_addr,
 					     sizeof(ip6_addr), 0);
 			if (err < 0)
 				goto out;
@@ -1360,14 +1425,14 @@ static int l2tp_tunnel_sock_create(struct net *net,
 			struct sockaddr_l2tpip ip_addr = {0};
 
 			err = sock_create_kern(net, AF_INET, SOCK_DGRAM,
-					  IPPROTO_L2TP, &sock);
+					       IPPROTO_L2TP, &sock);
 			if (err < 0)
 				goto out;
 
 			ip_addr.l2tp_family = AF_INET;
 			ip_addr.l2tp_addr = cfg->local_ip;
 			ip_addr.l2tp_conn_id = tunnel_id;
-			err = kernel_bind(sock, (struct sockaddr *) &ip_addr,
+			err = kernel_bind(sock, (struct sockaddr *)&ip_addr,
 					  sizeof(ip_addr));
 			if (err < 0)
 				goto out;
@@ -1375,7 +1440,7 @@ static int l2tp_tunnel_sock_create(struct net *net,
 			ip_addr.l2tp_family = AF_INET;
 			ip_addr.l2tp_addr = cfg->peer_ip;
 			ip_addr.l2tp_conn_id = peer_tunnel_id;
-			err = kernel_connect(sock, (struct sockaddr *) &ip_addr,
+			err = kernel_connect(sock, (struct sockaddr *)&ip_addr,
 					     sizeof(ip_addr), 0);
 			if (err < 0)
 				goto out;
@@ -1388,7 +1453,7 @@ static int l2tp_tunnel_sock_create(struct net *net,
 
 out:
 	*sockp = sock;
-	if ((err < 0) && sock) {
+	if (err < 0 && sock) {
 		kernel_sock_shutdown(sock, SHUT_RDWR);
 		sock_release(sock);
 		*sockp = NULL;
@@ -1399,17 +1464,18 @@ out:
 
 static struct lock_class_key l2tp_socket_class;
 
-int l2tp_tunnel_create(struct net *net, int fd, int version, u32 tunnel_id, u32 peer_tunnel_id, struct l2tp_tunnel_cfg *cfg, struct l2tp_tunnel **tunnelp)
+int l2tp_tunnel_create(struct net *net, int fd, int version, u32 tunnel_id, u32 peer_tunnel_id,
+		       struct l2tp_tunnel_cfg *cfg, struct l2tp_tunnel **tunnelp)
 {
 	struct l2tp_tunnel *tunnel = NULL;
 	int err;
 	enum l2tp_encap_type encap = L2TP_ENCAPTYPE_UDP;
 
-	if (cfg != NULL)
+	if (cfg)
 		encap = cfg->encap;
 
-	tunnel = kzalloc(sizeof(struct l2tp_tunnel), GFP_KERNEL);
-	if (tunnel == NULL) {
+	tunnel = kzalloc(sizeof(*tunnel), GFP_KERNEL);
+	if (!tunnel) {
 		err = -ENOMEM;
 		goto err;
 	}
@@ -1424,7 +1490,7 @@ int l2tp_tunnel_create(struct net *net, int fd, int version, u32 tunnel_id, u32
 	rwlock_init(&tunnel->hlist_lock);
 	tunnel->acpt_newsess = true;
 
-	if (cfg != NULL)
+	if (cfg)
 		tunnel->debug = cfg->debug;
 
 	tunnel->encap = encap;
@@ -1557,67 +1623,17 @@ void l2tp_tunnel_delete(struct l2tp_tunnel *tunnel)
 }
 EXPORT_SYMBOL_GPL(l2tp_tunnel_delete);
 
-/* Really kill the session.
- */
-void l2tp_session_free(struct l2tp_session *session)
-{
-	struct l2tp_tunnel *tunnel = session->tunnel;
-
-	BUG_ON(refcount_read(&session->ref_count) != 0);
-
-	if (tunnel) {
-		BUG_ON(tunnel->magic != L2TP_TUNNEL_MAGIC);
-		l2tp_tunnel_dec_refcount(tunnel);
-	}
-
-	kfree(session);
-}
-EXPORT_SYMBOL_GPL(l2tp_session_free);
-
-/* Remove an l2tp session from l2tp_core's hash lists.
- * Provides a tidyup interface for pseudowire code which can't just route all
- * shutdown via. l2tp_session_delete and a pseudowire-specific session_close
- * callback.
- */
-void __l2tp_session_unhash(struct l2tp_session *session)
-{
-	struct l2tp_tunnel *tunnel = session->tunnel;
-
-	/* Remove the session from core hashes */
-	if (tunnel) {
-		/* Remove from the per-tunnel hash */
-		write_lock_bh(&tunnel->hlist_lock);
-		hlist_del_init(&session->hlist);
-		write_unlock_bh(&tunnel->hlist_lock);
-
-		/* For L2TPv3 we have a per-net hash: remove from there, too */
-		if (tunnel->version != L2TP_HDR_VER_2) {
-			struct l2tp_net *pn = l2tp_pernet(tunnel->l2tp_net);
-			spin_lock_bh(&pn->l2tp_session_hlist_lock);
-			hlist_del_init_rcu(&session->global_hlist);
-			spin_unlock_bh(&pn->l2tp_session_hlist_lock);
-			synchronize_rcu();
-		}
-	}
-}
-EXPORT_SYMBOL_GPL(__l2tp_session_unhash);
-
-/* This function is used by the netlink SESSION_DELETE command and by
-   pseudowire modules.
- */
-int l2tp_session_delete(struct l2tp_session *session)
+void l2tp_session_delete(struct l2tp_session *session)
 {
 	if (test_and_set_bit(0, &session->dead))
-		return 0;
+		return;
 
-	__l2tp_session_unhash(session);
+	l2tp_session_unhash(session);
 	l2tp_session_queue_purge(session);
-	if (session->session_close != NULL)
+	if (session->session_close)
 		(*session->session_close)(session);
 
 	l2tp_session_dec_refcount(session);
-
-	return 0;
 }
 EXPORT_SYMBOL_GPL(l2tp_session_delete);
 
@@ -1636,16 +1652,16 @@ void l2tp_session_set_header_len(struct l2tp_session *session, int version)
 		if (session->tunnel->encap == L2TP_ENCAPTYPE_UDP)
 			session->hdr_len += 4;
 	}
-
 }
 EXPORT_SYMBOL_GPL(l2tp_session_set_header_len);
 
-struct l2tp_session *l2tp_session_create(int priv_size, struct l2tp_tunnel *tunnel, u32 session_id, u32 peer_session_id, struct l2tp_session_cfg *cfg)
+struct l2tp_session *l2tp_session_create(int priv_size, struct l2tp_tunnel *tunnel, u32 session_id,
+					 u32 peer_session_id, struct l2tp_session_cfg *cfg)
 {
 	struct l2tp_session *session;
 
-	session = kzalloc(sizeof(struct l2tp_session) + priv_size, GFP_KERNEL);
-	if (session != NULL) {
+	session = kzalloc(sizeof(*session) + priv_size, GFP_KERNEL);
+	if (session) {
 		session->magic = L2TP_SESSION_MAGIC;
 		session->tunnel = tunnel;
 
@@ -1687,11 +1703,6 @@ struct l2tp_session *l2tp_session_create(int priv_size, struct l2tp_tunnel *tunn
 			memcpy(&session->peer_cookie[0], &cfg->peer_cookie[0], cfg->peer_cookie_len);
 		}
 
-		if (tunnel->version == L2TP_HDR_VER_2)
-			session->build_header = l2tp_build_l2tpv2_header;
-		else
-			session->build_header = l2tp_build_l2tpv3_header;
-
 		l2tp_session_set_header_len(session, tunnel->version);
 
 		refcount_set(&session->ref_count, 1);
diff --git a/net/l2tp/l2tp_core.h b/net/l2tp/l2tp_core.h
index 10cf7c3dcbb3..3468d6b177a0 100644
--- a/net/l2tp/l2tp_core.h
+++ b/net/l2tp/l2tp_core.h
@@ -1,6 +1,5 @@
 /* SPDX-License-Identifier: GPL-2.0-only */
-/*
- * L2TP internal definitions.
+/* L2TP internal definitions.
  *
  * Copyright (c) 2008,2009 Katalix Systems Ltd
  */
@@ -16,17 +15,17 @@
 #include <net/xfrm.h>
 #endif
 
-/* Just some random numbers */
+/* Random numbers used for internal consistency checks of tunnel and session structures */
 #define L2TP_TUNNEL_MAGIC	0x42114DDA
 #define L2TP_SESSION_MAGIC	0x0C04EB7D
 
-/* Per tunnel, session hash table size */
+/* Per tunnel session hash table size */
 #define L2TP_HASH_BITS	4
-#define L2TP_HASH_SIZE	(1 << L2TP_HASH_BITS)
+#define L2TP_HASH_SIZE	BIT(L2TP_HASH_BITS)
 
-/* System-wide, session hash table size */
+/* System-wide session hash table size */
 #define L2TP_HASH_BITS_2	8
-#define L2TP_HASH_SIZE_2	(1 << L2TP_HASH_BITS_2)
+#define L2TP_HASH_SIZE_2	BIT(L2TP_HASH_BITS_2)
 
 struct sk_buff;
 
@@ -44,37 +43,34 @@ struct l2tp_stats {
 
 struct l2tp_tunnel;
 
-/* Describes a session. Contains information to determine incoming
- * packets and transmit outgoing ones.
- */
+/* L2TP session configuration */
 struct l2tp_session_cfg {
 	enum l2tp_pwtype	pw_type;
-	unsigned int		recv_seq:1;	/* expect receive packets with
-						 * sequence numbers? */
-	unsigned int		send_seq:1;	/* send packets with sequence
-						 * numbers? */
-	unsigned int		lns_mode:1;	/* behave as LNS? LAC enables
-						 * sequence numbers under
-						 * control of LNS. */
-	int			debug;		/* bitmask of debug message
-						 * categories */
+	unsigned int		recv_seq:1;	/* expect receive packets with sequence numbers? */
+	unsigned int		send_seq:1;	/* send packets with sequence numbers? */
+	unsigned int		lns_mode:1;	/* behave as LNS?
+						 * LAC enables sequence numbers under LNS control.
+						 */
+	int			debug;		/* bitmask of debug message categories */
 	u16			l2specific_type; /* Layer 2 specific type */
 	u8			cookie[8];	/* optional cookie */
 	int			cookie_len;	/* 0, 4 or 8 bytes */
 	u8			peer_cookie[8];	/* peer's cookie */
 	int			peer_cookie_len; /* 0, 4 or 8 bytes */
-	int			reorder_timeout; /* configured reorder timeout
-						  * (in jiffies) */
+	int			reorder_timeout; /* configured reorder timeout (in jiffies) */
 	char			*ifname;
 };
 
+/* Represents a session (pseudowire) instance.
+ * Tracks runtime state including cookies, dataplane packet sequencing, and IO statistics.
+ * Is linked into a per-tunnel session hashlist; and in the case of an L2TPv3 session into
+ * an additional per-net ("global") hashlist.
+ */
 struct l2tp_session {
-	int			magic;		/* should be
-						 * L2TP_SESSION_MAGIC */
+	int			magic;		/* should be L2TP_SESSION_MAGIC */
 	long			dead;
 
-	struct l2tp_tunnel	*tunnel;	/* back pointer to tunnel
-						 * context */
+	struct l2tp_tunnel	*tunnel;	/* back pointer to tunnel context */
 	u32			session_id;
 	u32			peer_session_id;
 	u8			cookie[8];
@@ -89,42 +85,53 @@ struct l2tp_session {
 	u32			nr_max;		/* max NR. Depends on tunnel */
 	u32			nr_window_size;	/* NR window size */
 	u32			nr_oos;		/* NR of last OOS packet */
-	int			nr_oos_count;	/* For OOS recovery */
+	int			nr_oos_count;	/* for OOS recovery */
 	int			nr_oos_count_max;
-	struct hlist_node	hlist;		/* Hash list node */
+	struct hlist_node	hlist;		/* hash list node */
 	refcount_t		ref_count;
 
 	char			name[32];	/* for logging */
 	char			ifname[IFNAMSIZ];
-	unsigned int		recv_seq:1;	/* expect receive packets with
-						 * sequence numbers? */
-	unsigned int		send_seq:1;	/* send packets with sequence
-						 * numbers? */
-	unsigned int		lns_mode:1;	/* behave as LNS? LAC enables
-						 * sequence numbers under
-						 * control of LNS. */
-	int			debug;		/* bitmask of debug message
-						 * categories */
-	int			reorder_timeout; /* configured reorder timeout
-						  * (in jiffies) */
+	unsigned int		recv_seq:1;	/* expect receive packets with sequence numbers? */
+	unsigned int		send_seq:1;	/* send packets with sequence numbers? */
+	unsigned int		lns_mode:1;	/* behave as LNS?
+						 * LAC enables sequence numbers under LNS control.
+						 */
+	int			debug;		/* bitmask of debug message categories */
+	int			reorder_timeout; /* configured reorder timeout (in jiffies) */
 	int			reorder_skip;	/* set if skip to next nr */
 	enum l2tp_pwtype	pwtype;
 	struct l2tp_stats	stats;
-	struct hlist_node	global_hlist;	/* Global hash list node */
+	struct hlist_node	global_hlist;	/* global hash list node */
 
-	int (*build_header)(struct l2tp_session *session, void *buf);
+	/* Session receive handler for data packets.
+	 * Each pseudowire implementation should implement this callback in order to
+	 * handle incoming packets.  Packets are passed to the pseudowire handler after
+	 * reordering, if data sequence numbers are enabled for the session.
+	 */
 	void (*recv_skb)(struct l2tp_session *session, struct sk_buff *skb, int data_len);
+
+	/* Session close handler.
+	 * Each pseudowire implementation may implement this callback in order to carry
+	 * out pseudowire-specific shutdown actions.
+	 * The callback is called by core after unhashing the session and purging its
+	 * reorder queue.
+	 */
 	void (*session_close)(struct l2tp_session *session);
+
+	/* Session show handler.
+	 * Pseudowire-specific implementation of debugfs session rendering.
+	 * The callback is called by l2tp_debugfs.c after rendering core session
+	 * information.
+	 */
 	void (*show)(struct seq_file *m, void *priv);
-	u8			priv[];	/* private data */
+
+	u8			priv[];		/* private data */
 };
 
-/* Describes the tunnel. It contains info to track all the associated
- * sessions so incoming packets can be sorted out
- */
+/* L2TP tunnel configuration */
 struct l2tp_tunnel_cfg {
-	int			debug;		/* bitmask of debug message
-						 * categories */
+	int			debug;		/* bitmask of debug message categories */
 	enum l2tp_encap_type	encap;
 
 	/* Used only for kernel-created sockets */
@@ -141,6 +148,12 @@ struct l2tp_tunnel_cfg {
 				udp6_zero_rx_checksums:1;
 };
 
+/* Represents a tunnel instance.
+ * Tracks runtime state including IO statistics.
+ * Holds the tunnel socket (either passed from userspace or directly created by the kernel).
+ * Maintains a hashlist of sessions belonging to the tunnel instance.
+ * Is linked into a per-net list of tunnels.
+ */
 struct l2tp_tunnel {
 	int			magic;		/* Should be L2TP_TUNNEL_MAGIC */
 
@@ -148,40 +161,51 @@ struct l2tp_tunnel {
 
 	struct rcu_head rcu;
 	rwlock_t		hlist_lock;	/* protect session_hlist */
-	bool			acpt_newsess;	/* Indicates whether this
-						 * tunnel accepts new sessions.
-						 * Protected by hlist_lock.
+	bool			acpt_newsess;	/* indicates whether this tunnel accepts
+						 * new sessions. Protected by hlist_lock.
 						 */
 	struct hlist_head	session_hlist[L2TP_HASH_SIZE];
-						/* hashed list of sessions,
-						 * hashed by id */
+						/* hashed list of sessions, hashed by id */
 	u32			tunnel_id;
 	u32			peer_tunnel_id;
 	int			version;	/* 2=>L2TPv2, 3=>L2TPv3 */
 
 	char			name[20];	/* for logging */
-	int			debug;		/* bitmask of debug message
-						 * categories */
+	int			debug;		/* bitmask of debug message categories */
 	enum l2tp_encap_type	encap;
 	struct l2tp_stats	stats;
 
-	struct list_head	list;		/* Keep a list of all tunnels */
+	struct list_head	list;		/* list node on per-namespace list of tunnels */
 	struct net		*l2tp_net;	/* the net we belong to */
 
 	refcount_t		ref_count;
-	void (*old_sk_destruct)(struct sock *);
-	struct sock		*sock;		/* Parent socket */
-	int			fd;		/* Parent fd, if tunnel socket
-						 * was created by userspace */
+	void (*old_sk_destruct)(struct sock *sk);
+	struct sock		*sock;		/* parent socket */
+	int			fd;		/* parent fd, if tunnel socket was created
+						 * by userspace
+						 */
 
 	struct work_struct	del_work;
 };
 
+/* Pseudowire ops callbacks for use with the l2tp genetlink interface */
 struct l2tp_nl_cmd_ops {
+	/* The pseudowire session create callback is responsible for creating a session
+	 * instance for a specific pseudowire type.
+	 * It must call l2tp_session_create and l2tp_session_register to register the
+	 * session instance, as well as carry out any pseudowire-specific initialisation.
+	 * It must return >= 0 on success, or an appropriate negative errno value on failure.
+	 */
 	int (*session_create)(struct net *net, struct l2tp_tunnel *tunnel,
 			      u32 session_id, u32 peer_session_id,
 			      struct l2tp_session_cfg *cfg);
-	int (*session_delete)(struct l2tp_session *session);
+
+	/* The pseudowire session delete callback is responsible for initiating the deletion
+	 * of a session instance.
+	 * It must call l2tp_session_delete, as well as carry out any pseudowire-specific
+	 * teardown actions.
+	 */
+	void (*session_delete)(struct l2tp_session *session);
 };
 
 static inline void *l2tp_session_priv(struct l2tp_session *session)
@@ -189,73 +213,68 @@ static inline void *l2tp_session_priv(struct l2tp_session *session)
 	return &session->priv[0];
 }
 
+/* Tunnel and session refcounts */
+void l2tp_tunnel_inc_refcount(struct l2tp_tunnel *tunnel);
+void l2tp_tunnel_dec_refcount(struct l2tp_tunnel *tunnel);
+void l2tp_session_inc_refcount(struct l2tp_session *session);
+void l2tp_session_dec_refcount(struct l2tp_session *session);
+
+/* Tunnel and session lookup.
+ * These functions take a reference on the instances they return, so
+ * the caller must ensure that the reference is dropped appropriately.
+ */
 struct l2tp_tunnel *l2tp_tunnel_get(const struct net *net, u32 tunnel_id);
 struct l2tp_tunnel *l2tp_tunnel_get_nth(const struct net *net, int nth);
 struct l2tp_session *l2tp_tunnel_get_session(struct l2tp_tunnel *tunnel,
 					     u32 session_id);
 
-void l2tp_tunnel_free(struct l2tp_tunnel *tunnel);
-
 struct l2tp_session *l2tp_session_get(const struct net *net, u32 session_id);
 struct l2tp_session *l2tp_session_get_nth(struct l2tp_tunnel *tunnel, int nth);
 struct l2tp_session *l2tp_session_get_by_ifname(const struct net *net,
 						const char *ifname);
 
+/* Tunnel and session lifetime management.
+ * Creation of a new instance is a two-step process: create, then register.
+ * Destruction is triggered using the *_delete functions, and completes asynchronously.
+ */
 int l2tp_tunnel_create(struct net *net, int fd, int version, u32 tunnel_id,
 		       u32 peer_tunnel_id, struct l2tp_tunnel_cfg *cfg,
 		       struct l2tp_tunnel **tunnelp);
 int l2tp_tunnel_register(struct l2tp_tunnel *tunnel, struct net *net,
 			 struct l2tp_tunnel_cfg *cfg);
-
 void l2tp_tunnel_delete(struct l2tp_tunnel *tunnel);
+
 struct l2tp_session *l2tp_session_create(int priv_size,
 					 struct l2tp_tunnel *tunnel,
 					 u32 session_id, u32 peer_session_id,
 					 struct l2tp_session_cfg *cfg);
 int l2tp_session_register(struct l2tp_session *session,
 			  struct l2tp_tunnel *tunnel);
+void l2tp_session_delete(struct l2tp_session *session);
 
-void __l2tp_session_unhash(struct l2tp_session *session);
-int l2tp_session_delete(struct l2tp_session *session);
-void l2tp_session_free(struct l2tp_session *session);
+/* Receive path helpers.  If data sequencing is enabled for the session these
+ * functions handle queuing and reordering prior to passing packets to the
+ * pseudowire code to be passed to userspace.
+ */
 void l2tp_recv_common(struct l2tp_session *session, struct sk_buff *skb,
 		      unsigned char *ptr, unsigned char *optr, u16 hdrflags,
 		      int length);
 int l2tp_udp_encap_recv(struct sock *sk, struct sk_buff *skb);
-void l2tp_session_set_header_len(struct l2tp_session *session, int version);
 
+/* Transmit path helpers for sending packets over the tunnel socket. */
+void l2tp_session_set_header_len(struct l2tp_session *session, int version);
 int l2tp_xmit_skb(struct l2tp_session *session, struct sk_buff *skb,
 		  int hdr_len);
 
-int l2tp_nl_register_ops(enum l2tp_pwtype pw_type,
-			 const struct l2tp_nl_cmd_ops *ops);
-void l2tp_nl_unregister_ops(enum l2tp_pwtype pw_type);
-int l2tp_ioctl(struct sock *sk, int cmd, unsigned long arg);
-
-static inline void l2tp_tunnel_inc_refcount(struct l2tp_tunnel *tunnel)
-{
-	refcount_inc(&tunnel->ref_count);
-}
-
-static inline void l2tp_tunnel_dec_refcount(struct l2tp_tunnel *tunnel)
-{
-	if (refcount_dec_and_test(&tunnel->ref_count))
-		l2tp_tunnel_free(tunnel);
-}
-
-/* Session reference counts. Incremented when code obtains a reference
- * to a session.
+/* Pseudowire management.
+ * Pseudowires should register with l2tp core on module init, and unregister
+ * on module exit.
  */
-static inline void l2tp_session_inc_refcount(struct l2tp_session *session)
-{
-	refcount_inc(&session->ref_count);
-}
+int l2tp_nl_register_ops(enum l2tp_pwtype pw_type, const struct l2tp_nl_cmd_ops *ops);
+void l2tp_nl_unregister_ops(enum l2tp_pwtype pw_type);
 
-static inline void l2tp_session_dec_refcount(struct l2tp_session *session)
-{
-	if (refcount_dec_and_test(&session->ref_count))
-		l2tp_session_free(session);
-}
+/* IOCTL helper for IP encap modules. */
+int l2tp_ioctl(struct sock *sk, int cmd, unsigned long arg);
 
 static inline int l2tp_get_l2specific_len(struct l2tp_session *session)
 {
diff --git a/net/l2tp/l2tp_debugfs.c b/net/l2tp/l2tp_debugfs.c
index 35bb4f3bdbe0..96cb9601c21b 100644
--- a/net/l2tp/l2tp_debugfs.c
+++ b/net/l2tp/l2tp_debugfs.c
@@ -1,6 +1,5 @@
 // SPDX-License-Identifier: GPL-2.0-or-later
-/*
- * L2TP subsystem debugfs
+/* L2TP subsystem debugfs
  *
  * Copyright (c) 2010 Katalix Systems Ltd
  */
@@ -59,11 +58,10 @@ static void l2tp_dfs_next_session(struct l2tp_dfs_seq_data *pd)
 	pd->session = l2tp_session_get_nth(pd->tunnel, pd->session_idx);
 	pd->session_idx++;
 
-	if (pd->session == NULL) {
+	if (!pd->session) {
 		pd->session_idx = 0;
 		l2tp_dfs_next_tunnel(pd);
 	}
-
 }
 
 static void *l2tp_dfs_seq_start(struct seq_file *m, loff_t *offs)
@@ -74,23 +72,25 @@ static void *l2tp_dfs_seq_start(struct seq_file *m, loff_t *offs)
 	if (!pos)
 		goto out;
 
-	BUG_ON(m->private == NULL);
+	if (WARN_ON(!m->private)) {
+		pd = NULL;
+		goto out;
+	}
 	pd = m->private;
 
-	if (pd->tunnel == NULL)
+	if (!pd->tunnel)
 		l2tp_dfs_next_tunnel(pd);
 	else
 		l2tp_dfs_next_session(pd);
 
 	/* NULL tunnel and session indicates end of list */
-	if ((pd->tunnel == NULL) && (pd->session == NULL))
+	if (!pd->tunnel && !pd->session)
 		pd = NULL;
 
 out:
 	return pd;
 }
 
-
 static void *l2tp_dfs_seq_next(struct seq_file *m, void *v, loff_t *pos)
 {
 	(*pos)++;
@@ -148,11 +148,13 @@ static void l2tp_dfs_seq_tunnel_show(struct seq_file *m, void *v)
 			const struct ipv6_pinfo *np = inet6_sk(tunnel->sock);
 
 			seq_printf(m, " from %pI6c to %pI6c\n",
-				&np->saddr, &tunnel->sock->sk_v6_daddr);
-		} else
+				   &np->saddr, &tunnel->sock->sk_v6_daddr);
+		}
 #endif
-		seq_printf(m, " from %pI4 to %pI4\n",
-			   &inet->inet_saddr, &inet->inet_daddr);
+		if (tunnel->sock->sk_family == AF_INET)
+			seq_printf(m, " from %pI4 to %pI4\n",
+				   &inet->inet_saddr, &inet->inet_daddr);
+
 		if (tunnel->encap == L2TP_ENCAPTYPE_UDP)
 			seq_printf(m, " source port %hu, dest port %hu\n",
 				   ntohs(inet->inet_sport), ntohs(inet->inet_dport));
@@ -202,7 +204,7 @@ static void l2tp_dfs_seq_session_show(struct seq_file *m, void *v)
 			seq_printf(m, "%02x%02x%02x%02x",
 				   session->cookie[4], session->cookie[5],
 				   session->cookie[6], session->cookie[7]);
-		seq_printf(m, "\n");
+		seq_puts(m, "\n");
 	}
 	if (session->peer_cookie_len) {
 		seq_printf(m, "   peer cookie %02x%02x%02x%02x",
@@ -212,7 +214,7 @@ static void l2tp_dfs_seq_session_show(struct seq_file *m, void *v)
 			seq_printf(m, "%02x%02x%02x%02x",
 				   session->peer_cookie[4], session->peer_cookie[5],
 				   session->peer_cookie[6], session->peer_cookie[7]);
-		seq_printf(m, "\n");
+		seq_puts(m, "\n");
 	}
 
 	seq_printf(m, "   %hu/%hu tx %ld/%ld/%ld rx %ld/%ld/%ld\n",
@@ -224,7 +226,7 @@ static void l2tp_dfs_seq_session_show(struct seq_file *m, void *v)
 		   atomic_long_read(&session->stats.rx_bytes),
 		   atomic_long_read(&session->stats.rx_errors));
 
-	if (session->show != NULL)
+	if (session->show)
 		session->show(m, session);
 }
 
@@ -271,7 +273,7 @@ static int l2tp_dfs_seq_open(struct inode *inode, struct file *file)
 	int rc = -ENOMEM;
 
 	pd = kzalloc(sizeof(*pd), GFP_KERNEL);
-	if (pd == NULL)
+	if (!pd)
 		goto out;
 
 	/* Derive the network namespace from the pid opening the
diff --git a/net/l2tp/l2tp_eth.c b/net/l2tp/l2tp_eth.c
index fd5ac2788e45..7ed2b4eced94 100644
--- a/net/l2tp/l2tp_eth.c
+++ b/net/l2tp/l2tp_eth.c
@@ -1,6 +1,5 @@
 // SPDX-License-Identifier: GPL-2.0-or-later
-/*
- * L2TPv3 ethernet pseudowire driver
+/* L2TPv3 ethernet pseudowire driver
  *
  * Copyright (c) 2008,2009,2010 Katalix Systems Ltd
  */
@@ -51,7 +50,6 @@ struct l2tp_eth_sess {
 	struct net_device __rcu *dev;
 };
 
-
 static int l2tp_eth_dev_init(struct net_device *dev)
 {
 	eth_hw_addr_random(dev);
@@ -73,7 +71,7 @@ static void l2tp_eth_dev_uninit(struct net_device *dev)
 	 */
 }
 
-static int l2tp_eth_dev_xmit(struct sk_buff *skb, struct net_device *dev)
+static netdev_tx_t l2tp_eth_dev_xmit(struct sk_buff *skb, struct net_device *dev)
 {
 	struct l2tp_eth *priv = netdev_priv(dev);
 	struct l2tp_session *session = priv->session;
@@ -94,13 +92,12 @@ static void l2tp_eth_get_stats64(struct net_device *dev,
 {
 	struct l2tp_eth *priv = netdev_priv(dev);
 
-	stats->tx_bytes   = (unsigned long) atomic_long_read(&priv->tx_bytes);
-	stats->tx_packets = (unsigned long) atomic_long_read(&priv->tx_packets);
-	stats->tx_dropped = (unsigned long) atomic_long_read(&priv->tx_dropped);
-	stats->rx_bytes   = (unsigned long) atomic_long_read(&priv->rx_bytes);
-	stats->rx_packets = (unsigned long) atomic_long_read(&priv->rx_packets);
-	stats->rx_errors  = (unsigned long) atomic_long_read(&priv->rx_errors);
-
+	stats->tx_bytes   = (unsigned long)atomic_long_read(&priv->tx_bytes);
+	stats->tx_packets = (unsigned long)atomic_long_read(&priv->tx_packets);
+	stats->tx_dropped = (unsigned long)atomic_long_read(&priv->tx_dropped);
+	stats->rx_bytes   = (unsigned long)atomic_long_read(&priv->rx_bytes);
+	stats->rx_packets = (unsigned long)atomic_long_read(&priv->rx_packets);
+	stats->rx_errors  = (unsigned long)atomic_long_read(&priv->rx_errors);
 }
 
 static const struct net_device_ops l2tp_eth_netdev_ops = {
@@ -348,13 +345,11 @@ err:
 	return rc;
 }
 
-
 static const struct l2tp_nl_cmd_ops l2tp_eth_nl_cmd_ops = {
 	.session_create	= l2tp_eth_create,
 	.session_delete	= l2tp_session_delete,
 };
 
-
 static int __init l2tp_eth_init(void)
 {
 	int err = 0;
diff --git a/net/l2tp/l2tp_ip.c b/net/l2tp/l2tp_ip.c
index 955662a6dee7..df2a35b5714a 100644
--- a/net/l2tp/l2tp_ip.c
+++ b/net/l2tp/l2tp_ip.c
@@ -1,6 +1,5 @@
 // SPDX-License-Identifier: GPL-2.0-or-later
-/*
- * L2TPv3 IP encapsulation support
+/* L2TPv3 IP encapsulation support
  *
  * Copyright (c) 2008,2009,2010 Katalix Systems Ltd
  */
@@ -125,8 +124,9 @@ static int l2tp_ip_recv(struct sk_buff *skb)
 		goto discard;
 
 	/* Point to L2TP header */
-	optr = ptr = skb->data;
-	session_id = ntohl(*((__be32 *) ptr));
+	optr = skb->data;
+	ptr = skb->data;
+	session_id = ntohl(*((__be32 *)ptr));
 	ptr += 4;
 
 	/* RFC3931: L2TP/IP packets have the first 4 bytes containing
@@ -154,7 +154,8 @@ static int l2tp_ip_recv(struct sk_buff *skb)
 			goto discard_sess;
 
 		/* Point to L2TP header */
-		optr = ptr = skb->data;
+		optr = skb->data;
+		ptr = skb->data;
 		ptr += 4;
 		pr_debug("%s: ip recv\n", tunnel->name);
 		print_hex_dump_bytes("", DUMP_PREFIX_OFFSET, ptr, length);
@@ -176,7 +177,7 @@ pass_up:
 	if ((skb->data[0] & 0xc0) != 0xc0)
 		goto discard;
 
-	tunnel_id = ntohl(*(__be32 *) &skb->data[4]);
+	tunnel_id = ntohl(*(__be32 *)&skb->data[4]);
 	iph = (struct iphdr *)skb_network_header(skb);
 
 	read_lock_bh(&l2tp_ip_lock);
@@ -260,7 +261,7 @@ static void l2tp_ip_destroy_sock(struct sock *sk)
 static int l2tp_ip_bind(struct sock *sk, struct sockaddr *uaddr, int addr_len)
 {
 	struct inet_sock *inet = inet_sk(sk);
-	struct sockaddr_l2tpip *addr = (struct sockaddr_l2tpip *) uaddr;
+	struct sockaddr_l2tpip *addr = (struct sockaddr_l2tpip *)uaddr;
 	struct net *net = sock_net(sk);
 	int ret;
 	int chk_addr_ret;
@@ -285,8 +286,10 @@ static int l2tp_ip_bind(struct sock *sk, struct sockaddr *uaddr, int addr_len)
 	    chk_addr_ret != RTN_MULTICAST && chk_addr_ret != RTN_BROADCAST)
 		goto out;
 
-	if (addr->l2tp_addr.s_addr)
-		inet->inet_rcv_saddr = inet->inet_saddr = addr->l2tp_addr.s_addr;
+	if (addr->l2tp_addr.s_addr) {
+		inet->inet_rcv_saddr = addr->l2tp_addr.s_addr;
+		inet->inet_saddr = addr->l2tp_addr.s_addr;
+	}
 	if (chk_addr_ret == RTN_MULTICAST || chk_addr_ret == RTN_BROADCAST)
 		inet->inet_saddr = 0;  /* Use device */
 
@@ -316,7 +319,7 @@ out:
 
 static int l2tp_ip_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
 {
-	struct sockaddr_l2tpip *lsa = (struct sockaddr_l2tpip *) uaddr;
+	struct sockaddr_l2tpip *lsa = (struct sockaddr_l2tpip *)uaddr;
 	int rc;
 
 	if (addr_len < sizeof(*lsa))
@@ -375,6 +378,7 @@ static int l2tp_ip_getname(struct socket *sock, struct sockaddr *uaddr,
 		lsa->l2tp_addr.s_addr = inet->inet_daddr;
 	} else {
 		__be32 addr = inet->inet_rcv_saddr;
+
 		if (!addr)
 			addr = inet->inet_saddr;
 		lsa->l2tp_conn_id = lsk->conn_id;
@@ -422,6 +426,7 @@ static int l2tp_ip_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
 	/* Get and verify the address. */
 	if (msg->msg_name) {
 		DECLARE_SOCKADDR(struct sockaddr_l2tpip *, lip, msg->msg_name);
+
 		rc = -EINVAL;
 		if (msg->msg_namelen < sizeof(*lip))
 			goto out;
@@ -456,7 +461,7 @@ static int l2tp_ip_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
 	skb_reset_transport_header(skb);
 
 	/* Insert 0 session_id */
-	*((__be32 *) skb_put(skb, 4)) = 0;
+	*((__be32 *)skb_put(skb, 4)) = 0;
 
 	/* Copy user data into skb */
 	rc = memcpy_from_msg(skb_put(skb, len), msg, len);
@@ -467,10 +472,10 @@ static int l2tp_ip_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
 
 	fl4 = &inet->cork.fl.u.ip4;
 	if (connected)
-		rt = (struct rtable *) __sk_dst_check(sk, 0);
+		rt = (struct rtable *)__sk_dst_check(sk, 0);
 
 	rcu_read_lock();
-	if (rt == NULL) {
+	if (!rt) {
 		const struct ip_options_rcu *inet_opt;
 
 		inet_opt = rcu_dereference(inet->inet_opt);
@@ -592,7 +597,7 @@ int l2tp_ioctl(struct sock *sk, int cmd, unsigned long arg)
 
 	return put_user(amount, (int __user *)arg);
 }
-EXPORT_SYMBOL(l2tp_ioctl);
+EXPORT_SYMBOL_GPL(l2tp_ioctl);
 
 static struct proto l2tp_ip_prot = {
 	.name		   = "L2TP/IP",
@@ -612,10 +617,6 @@ static struct proto l2tp_ip_prot = {
 	.hash		   = l2tp_ip_hash,
 	.unhash		   = l2tp_ip_unhash,
 	.obj_size	   = sizeof(struct l2tp_ip_sock),
-#ifdef CONFIG_COMPAT
-	.compat_setsockopt = compat_ip_setsockopt,
-	.compat_getsockopt = compat_ip_getsockopt,
-#endif
 };
 
 static const struct proto_ops l2tp_ip_ops = {
@@ -638,10 +639,6 @@ static const struct proto_ops l2tp_ip_ops = {
 	.recvmsg	   = sock_common_recvmsg,
 	.mmap		   = sock_no_mmap,
 	.sendpage	   = sock_no_sendpage,
-#ifdef CONFIG_COMPAT
-	.compat_setsockopt = compat_sock_common_setsockopt,
-	.compat_getsockopt = compat_sock_common_getsockopt,
-#endif
 };
 
 static struct inet_protosw l2tp_ip_protosw = {
diff --git a/net/l2tp/l2tp_ip6.c b/net/l2tp/l2tp_ip6.c
index 526ed2c24dd5..bc757bc7e264 100644
--- a/net/l2tp/l2tp_ip6.c
+++ b/net/l2tp/l2tp_ip6.c
@@ -1,6 +1,5 @@
 // SPDX-License-Identifier: GPL-2.0-or-later
-/*
- * L2TPv3 IP encapsulation support for IPv6
+/* L2TPv3 IP encapsulation support for IPv6
  *
  * Copyright (c) 2012 Katalix Systems Ltd
  */
@@ -38,7 +37,8 @@ struct l2tp_ip6_sock {
 	u32			peer_conn_id;
 
 	/* ipv6_pinfo has to be the last member of l2tp_ip6_sock, see
-	   inet6_sk_generic */
+	 * inet6_sk_generic
+	 */
 	struct ipv6_pinfo	inet6;
 };
 
@@ -137,8 +137,9 @@ static int l2tp_ip6_recv(struct sk_buff *skb)
 		goto discard;
 
 	/* Point to L2TP header */
-	optr = ptr = skb->data;
-	session_id = ntohl(*((__be32 *) ptr));
+	optr = skb->data;
+	ptr = skb->data;
+	session_id = ntohl(*((__be32 *)ptr));
 	ptr += 4;
 
 	/* RFC3931: L2TP/IP packets have the first 4 bytes containing
@@ -166,7 +167,8 @@ static int l2tp_ip6_recv(struct sk_buff *skb)
 			goto discard_sess;
 
 		/* Point to L2TP header */
-		optr = ptr = skb->data;
+		optr = skb->data;
+		ptr = skb->data;
 		ptr += 4;
 		pr_debug("%s: ip recv\n", tunnel->name);
 		print_hex_dump_bytes("", DUMP_PREFIX_OFFSET, ptr, length);
@@ -188,7 +190,7 @@ pass_up:
 	if ((skb->data[0] & 0xc0) != 0xc0)
 		goto discard;
 
-	tunnel_id = ntohl(*(__be32 *) &skb->data[4]);
+	tunnel_id = ntohl(*(__be32 *)&skb->data[4]);
 	iph = ipv6_hdr(skb);
 
 	read_lock_bh(&l2tp_ip6_lock);
@@ -276,7 +278,7 @@ static int l2tp_ip6_bind(struct sock *sk, struct sockaddr *uaddr, int addr_len)
 {
 	struct inet_sock *inet = inet_sk(sk);
 	struct ipv6_pinfo *np = inet6_sk(sk);
-	struct sockaddr_l2tpip6 *addr = (struct sockaddr_l2tpip6 *) uaddr;
+	struct sockaddr_l2tpip6 *addr = (struct sockaddr_l2tpip6 *)uaddr;
 	struct net *net = sock_net(sk);
 	__be32 v4addr = 0;
 	int bound_dev_if;
@@ -375,8 +377,8 @@ out_unlock:
 static int l2tp_ip6_connect(struct sock *sk, struct sockaddr *uaddr,
 			    int addr_len)
 {
-	struct sockaddr_l2tpip6 *lsa = (struct sockaddr_l2tpip6 *) uaddr;
-	struct sockaddr_in6	*usin = (struct sockaddr_in6 *) uaddr;
+	struct sockaddr_l2tpip6 *lsa = (struct sockaddr_l2tpip6 *)uaddr;
+	struct sockaddr_in6	*usin = (struct sockaddr_in6 *)uaddr;
 	struct in6_addr	*daddr;
 	int	addr_type;
 	int rc;
@@ -486,7 +488,7 @@ static int l2tp_ip6_push_pending_frames(struct sock *sk)
 	int err = 0;
 
 	skb = skb_peek(&sk->sk_write_queue);
-	if (skb == NULL)
+	if (!skb)
 		goto out;
 
 	transhdr = (__be32 *)skb_transport_header(skb);
@@ -519,7 +521,7 @@ static int l2tp_ip6_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
 	int err;
 
 	/* Rough check on arithmetic overflow,
-	   better check is made in ip6_append_data().
+	 * better check is made in ip6_append_data().
 	 */
 	if (len > INT_MAX)
 		return -EMSGSIZE;
@@ -528,9 +530,7 @@ static int l2tp_ip6_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
 	if (msg->msg_flags & MSG_OOB)
 		return -EOPNOTSUPP;
 
-	/*
-	 *	Get and verify the address.
-	 */
+	/* Get and verify the address */
 	memset(&fl6, 0, sizeof(fl6));
 
 	fl6.flowi6_mark = sk->sk_mark;
@@ -548,15 +548,14 @@ static int l2tp_ip6_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
 		daddr = &lsa->l2tp_addr;
 		if (np->sndflow) {
 			fl6.flowlabel = lsa->l2tp_flowinfo & IPV6_FLOWINFO_MASK;
-			if (fl6.flowlabel&IPV6_FLOWLABEL_MASK) {
+			if (fl6.flowlabel & IPV6_FLOWLABEL_MASK) {
 				flowlabel = fl6_sock_lookup(sk, fl6.flowlabel);
 				if (IS_ERR(flowlabel))
 					return -EINVAL;
 			}
 		}
 
-		/*
-		 * Otherwise it will be difficult to maintain
+		/* Otherwise it will be difficult to maintain
 		 * sk->sk_dst_cache.
 		 */
 		if (sk->sk_state == TCP_ESTABLISHED &&
@@ -594,7 +593,7 @@ static int l2tp_ip6_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
 			if (IS_ERR(flowlabel))
 				return -EINVAL;
 		}
-		if (!(opt->opt_nflen|opt->opt_flen))
+		if (!(opt->opt_nflen | opt->opt_flen))
 			opt = NULL;
 	}
 
@@ -745,10 +744,6 @@ static struct proto l2tp_ip6_prot = {
 	.hash		   = l2tp_ip6_hash,
 	.unhash		   = l2tp_ip6_unhash,
 	.obj_size	   = sizeof(struct l2tp_ip6_sock),
-#ifdef CONFIG_COMPAT
-	.compat_setsockopt = compat_ipv6_setsockopt,
-	.compat_getsockopt = compat_ipv6_getsockopt,
-#endif
 };
 
 static const struct proto_ops l2tp_ip6_ops = {
@@ -773,8 +768,6 @@ static const struct proto_ops l2tp_ip6_ops = {
 	.sendpage	   = sock_no_sendpage,
 #ifdef CONFIG_COMPAT
 	.compat_ioctl	   = inet6_compat_ioctl,
-	.compat_setsockopt = compat_sock_common_setsockopt,
-	.compat_getsockopt = compat_sock_common_getsockopt,
 #endif
 };
 
diff --git a/net/l2tp/l2tp_netlink.c b/net/l2tp/l2tp_netlink.c
index ebb381c3f1b9..def78eebca4c 100644
--- a/net/l2tp/l2tp_netlink.c
+++ b/net/l2tp/l2tp_netlink.c
@@ -1,6 +1,5 @@
 // SPDX-License-Identifier: GPL-2.0-only
-/*
- * L2TP netlink layer, for management
+/* L2TP netlink layer, for management
  *
  * Copyright (c) 2008,2009,2010 Katalix Systems Ltd
  *
@@ -27,7 +26,6 @@
 
 #include "l2tp_core.h"
 
-
 static struct genl_family l2tp_nl_family;
 
 static const struct genl_multicast_group l2tp_multicast_group[] = {
@@ -157,81 +155,82 @@ static int l2tp_session_notify(struct genl_family *family,
 	return ret;
 }
 
+static int l2tp_nl_cmd_tunnel_create_get_addr(struct nlattr **attrs, struct l2tp_tunnel_cfg *cfg)
+{
+	if (attrs[L2TP_ATTR_UDP_SPORT])
+		cfg->local_udp_port = nla_get_u16(attrs[L2TP_ATTR_UDP_SPORT]);
+	if (attrs[L2TP_ATTR_UDP_DPORT])
+		cfg->peer_udp_port = nla_get_u16(attrs[L2TP_ATTR_UDP_DPORT]);
+	cfg->use_udp_checksums = nla_get_flag(attrs[L2TP_ATTR_UDP_CSUM]);
+
+	/* Must have either AF_INET or AF_INET6 address for source and destination */
+#if IS_ENABLED(CONFIG_IPV6)
+	if (attrs[L2TP_ATTR_IP6_SADDR] && attrs[L2TP_ATTR_IP6_DADDR]) {
+		cfg->local_ip6 = nla_data(attrs[L2TP_ATTR_IP6_SADDR]);
+		cfg->peer_ip6 = nla_data(attrs[L2TP_ATTR_IP6_DADDR]);
+		cfg->udp6_zero_tx_checksums = nla_get_flag(attrs[L2TP_ATTR_UDP_ZERO_CSUM6_TX]);
+		cfg->udp6_zero_rx_checksums = nla_get_flag(attrs[L2TP_ATTR_UDP_ZERO_CSUM6_RX]);
+		return 0;
+	}
+#endif
+	if (attrs[L2TP_ATTR_IP_SADDR] && attrs[L2TP_ATTR_IP_DADDR]) {
+		cfg->local_ip.s_addr = nla_get_in_addr(attrs[L2TP_ATTR_IP_SADDR]);
+		cfg->peer_ip.s_addr = nla_get_in_addr(attrs[L2TP_ATTR_IP_DADDR]);
+		return 0;
+	}
+	return -EINVAL;
+}
+
 static int l2tp_nl_cmd_tunnel_create(struct sk_buff *skb, struct genl_info *info)
 {
 	u32 tunnel_id;
 	u32 peer_tunnel_id;
 	int proto_version;
-	int fd;
+	int fd = -1;
 	int ret = 0;
 	struct l2tp_tunnel_cfg cfg = { 0, };
 	struct l2tp_tunnel *tunnel;
 	struct net *net = genl_info_net(info);
+	struct nlattr **attrs = info->attrs;
 
-	if (!info->attrs[L2TP_ATTR_CONN_ID]) {
+	if (!attrs[L2TP_ATTR_CONN_ID]) {
 		ret = -EINVAL;
 		goto out;
 	}
-	tunnel_id = nla_get_u32(info->attrs[L2TP_ATTR_CONN_ID]);
+	tunnel_id = nla_get_u32(attrs[L2TP_ATTR_CONN_ID]);
 
-	if (!info->attrs[L2TP_ATTR_PEER_CONN_ID]) {
+	if (!attrs[L2TP_ATTR_PEER_CONN_ID]) {
 		ret = -EINVAL;
 		goto out;
 	}
-	peer_tunnel_id = nla_get_u32(info->attrs[L2TP_ATTR_PEER_CONN_ID]);
+	peer_tunnel_id = nla_get_u32(attrs[L2TP_ATTR_PEER_CONN_ID]);
 
-	if (!info->attrs[L2TP_ATTR_PROTO_VERSION]) {
+	if (!attrs[L2TP_ATTR_PROTO_VERSION]) {
 		ret = -EINVAL;
 		goto out;
 	}
-	proto_version = nla_get_u8(info->attrs[L2TP_ATTR_PROTO_VERSION]);
+	proto_version = nla_get_u8(attrs[L2TP_ATTR_PROTO_VERSION]);
 
-	if (!info->attrs[L2TP_ATTR_ENCAP_TYPE]) {
+	if (!attrs[L2TP_ATTR_ENCAP_TYPE]) {
 		ret = -EINVAL;
 		goto out;
 	}
-	cfg.encap = nla_get_u16(info->attrs[L2TP_ATTR_ENCAP_TYPE]);
-
-	fd = -1;
-	if (info->attrs[L2TP_ATTR_FD]) {
-		fd = nla_get_u32(info->attrs[L2TP_ATTR_FD]);
+	cfg.encap = nla_get_u16(attrs[L2TP_ATTR_ENCAP_TYPE]);
+
+	/* Managed tunnels take the tunnel socket from userspace.
+	 * Unmanaged tunnels must call out the source and destination addresses
+	 * for the kernel to create the tunnel socket itself.
+	 */
+	if (attrs[L2TP_ATTR_FD]) {
+		fd = nla_get_u32(attrs[L2TP_ATTR_FD]);
 	} else {
-#if IS_ENABLED(CONFIG_IPV6)
-		if (info->attrs[L2TP_ATTR_IP6_SADDR] &&
-		    info->attrs[L2TP_ATTR_IP6_DADDR]) {
-			cfg.local_ip6 = nla_data(
-				info->attrs[L2TP_ATTR_IP6_SADDR]);
-			cfg.peer_ip6 = nla_data(
-				info->attrs[L2TP_ATTR_IP6_DADDR]);
-		} else
-#endif
-		if (info->attrs[L2TP_ATTR_IP_SADDR] &&
-		    info->attrs[L2TP_ATTR_IP_DADDR]) {
-			cfg.local_ip.s_addr = nla_get_in_addr(
-				info->attrs[L2TP_ATTR_IP_SADDR]);
-			cfg.peer_ip.s_addr = nla_get_in_addr(
-				info->attrs[L2TP_ATTR_IP_DADDR]);
-		} else {
-			ret = -EINVAL;
+		ret = l2tp_nl_cmd_tunnel_create_get_addr(attrs, &cfg);
+		if (ret < 0)
 			goto out;
-		}
-		if (info->attrs[L2TP_ATTR_UDP_SPORT])
-			cfg.local_udp_port = nla_get_u16(info->attrs[L2TP_ATTR_UDP_SPORT]);
-		if (info->attrs[L2TP_ATTR_UDP_DPORT])
-			cfg.peer_udp_port = nla_get_u16(info->attrs[L2TP_ATTR_UDP_DPORT]);
-		cfg.use_udp_checksums = nla_get_flag(
-			info->attrs[L2TP_ATTR_UDP_CSUM]);
-
-#if IS_ENABLED(CONFIG_IPV6)
-		cfg.udp6_zero_tx_checksums = nla_get_flag(
-			info->attrs[L2TP_ATTR_UDP_ZERO_CSUM6_TX]);
-		cfg.udp6_zero_rx_checksums = nla_get_flag(
-			info->attrs[L2TP_ATTR_UDP_ZERO_CSUM6_RX]);
-#endif
 	}
 
-	if (info->attrs[L2TP_ATTR_DEBUG])
-		cfg.debug = nla_get_u32(info->attrs[L2TP_ATTR_DEBUG]);
+	if (attrs[L2TP_ATTR_DEBUG])
+		cfg.debug = nla_get_u32(attrs[L2TP_ATTR_DEBUG]);
 
 	ret = -EINVAL;
 	switch (cfg.encap) {
@@ -320,16 +319,79 @@ out:
 	return ret;
 }
 
+#if IS_ENABLED(CONFIG_IPV6)
+static int l2tp_nl_tunnel_send_addr6(struct sk_buff *skb, struct sock *sk,
+				     enum l2tp_encap_type encap)
+{
+	struct inet_sock *inet = inet_sk(sk);
+	struct ipv6_pinfo *np = inet6_sk(sk);
+
+	switch (encap) {
+	case L2TP_ENCAPTYPE_UDP:
+		if (udp_get_no_check6_tx(sk) &&
+		    nla_put_flag(skb, L2TP_ATTR_UDP_ZERO_CSUM6_TX))
+			return -1;
+		if (udp_get_no_check6_rx(sk) &&
+		    nla_put_flag(skb, L2TP_ATTR_UDP_ZERO_CSUM6_RX))
+			return -1;
+		if (nla_put_u16(skb, L2TP_ATTR_UDP_SPORT, ntohs(inet->inet_sport)) ||
+		    nla_put_u16(skb, L2TP_ATTR_UDP_DPORT, ntohs(inet->inet_dport)))
+			return -1;
+		fallthrough;
+	case L2TP_ENCAPTYPE_IP:
+		if (nla_put_in6_addr(skb, L2TP_ATTR_IP6_SADDR, &np->saddr) ||
+		    nla_put_in6_addr(skb, L2TP_ATTR_IP6_DADDR, &sk->sk_v6_daddr))
+			return -1;
+		break;
+	}
+	return 0;
+}
+#endif
+
+static int l2tp_nl_tunnel_send_addr4(struct sk_buff *skb, struct sock *sk,
+				     enum l2tp_encap_type encap)
+{
+	struct inet_sock *inet = inet_sk(sk);
+
+	switch (encap) {
+	case L2TP_ENCAPTYPE_UDP:
+		if (nla_put_u8(skb, L2TP_ATTR_UDP_CSUM, !sk->sk_no_check_tx) ||
+		    nla_put_u16(skb, L2TP_ATTR_UDP_SPORT, ntohs(inet->inet_sport)) ||
+		    nla_put_u16(skb, L2TP_ATTR_UDP_DPORT, ntohs(inet->inet_dport)))
+			return -1;
+		fallthrough;
+	case L2TP_ENCAPTYPE_IP:
+		if (nla_put_in_addr(skb, L2TP_ATTR_IP_SADDR, inet->inet_saddr) ||
+		    nla_put_in_addr(skb, L2TP_ATTR_IP_DADDR, inet->inet_daddr))
+			return -1;
+		break;
+	}
+
+	return 0;
+}
+
+/* Append attributes for the tunnel address, handling the different attribute types
+ * used for different tunnel encapsulation and AF_INET v.s. AF_INET6.
+ */
+static int l2tp_nl_tunnel_send_addr(struct sk_buff *skb, struct l2tp_tunnel *tunnel)
+{
+	struct sock *sk = tunnel->sock;
+
+	if (!sk)
+		return 0;
+
+#if IS_ENABLED(CONFIG_IPV6)
+	if (sk->sk_family == AF_INET6)
+		return l2tp_nl_tunnel_send_addr6(skb, sk, tunnel->encap);
+#endif
+	return l2tp_nl_tunnel_send_addr4(skb, sk, tunnel->encap);
+}
+
 static int l2tp_nl_tunnel_send(struct sk_buff *skb, u32 portid, u32 seq, int flags,
 			       struct l2tp_tunnel *tunnel, u8 cmd)
 {
 	void *hdr;
 	struct nlattr *nest;
-	struct sock *sk = NULL;
-	struct inet_sock *inet;
-#if IS_ENABLED(CONFIG_IPV6)
-	struct ipv6_pinfo *np = NULL;
-#endif
 
 	hdr = genlmsg_put(skb, portid, seq, &l2tp_nl_family, flags, cmd);
 	if (!hdr)
@@ -343,7 +405,7 @@ static int l2tp_nl_tunnel_send(struct sk_buff *skb, u32 portid, u32 seq, int fla
 		goto nla_put_failure;
 
 	nest = nla_nest_start_noflag(skb, L2TP_ATTR_STATS);
-	if (nest == NULL)
+	if (!nest)
 		goto nla_put_failure;
 
 	if (nla_put_u64_64bit(skb, L2TP_ATTR_TX_PACKETS,
@@ -373,58 +435,9 @@ static int l2tp_nl_tunnel_send(struct sk_buff *skb, u32 portid, u32 seq, int fla
 		goto nla_put_failure;
 	nla_nest_end(skb, nest);
 
-	sk = tunnel->sock;
-	if (!sk)
-		goto out;
-
-#if IS_ENABLED(CONFIG_IPV6)
-	if (sk->sk_family == AF_INET6)
-		np = inet6_sk(sk);
-#endif
-
-	inet = inet_sk(sk);
-
-	switch (tunnel->encap) {
-	case L2TP_ENCAPTYPE_UDP:
-		switch (sk->sk_family) {
-		case AF_INET:
-			if (nla_put_u8(skb, L2TP_ATTR_UDP_CSUM, !sk->sk_no_check_tx))
-				goto nla_put_failure;
-			break;
-#if IS_ENABLED(CONFIG_IPV6)
-		case AF_INET6:
-			if (udp_get_no_check6_tx(sk) &&
-			    nla_put_flag(skb, L2TP_ATTR_UDP_ZERO_CSUM6_TX))
-				goto nla_put_failure;
-			if (udp_get_no_check6_rx(sk) &&
-			    nla_put_flag(skb, L2TP_ATTR_UDP_ZERO_CSUM6_RX))
-				goto nla_put_failure;
-			break;
-#endif
-		}
-		if (nla_put_u16(skb, L2TP_ATTR_UDP_SPORT, ntohs(inet->inet_sport)) ||
-		    nla_put_u16(skb, L2TP_ATTR_UDP_DPORT, ntohs(inet->inet_dport)))
-			goto nla_put_failure;
-		/* fall through  */
-	case L2TP_ENCAPTYPE_IP:
-#if IS_ENABLED(CONFIG_IPV6)
-		if (np) {
-			if (nla_put_in6_addr(skb, L2TP_ATTR_IP6_SADDR,
-					     &np->saddr) ||
-			    nla_put_in6_addr(skb, L2TP_ATTR_IP6_DADDR,
-					     &sk->sk_v6_daddr))
-				goto nla_put_failure;
-		} else
-#endif
-		if (nla_put_in_addr(skb, L2TP_ATTR_IP_SADDR,
-				    inet->inet_saddr) ||
-		    nla_put_in_addr(skb, L2TP_ATTR_IP_DADDR,
-				    inet->inet_daddr))
-			goto nla_put_failure;
-		break;
-	}
+	if (l2tp_nl_tunnel_send_addr(skb, tunnel))
+		goto nla_put_failure;
 
-out:
 	genlmsg_end(skb, hdr);
 	return 0;
 
@@ -485,7 +498,7 @@ static int l2tp_nl_cmd_tunnel_dump(struct sk_buff *skb, struct netlink_callback
 
 	for (;;) {
 		tunnel = l2tp_tunnel_get_nth(net, ti);
-		if (tunnel == NULL)
+		if (!tunnel)
 			goto out;
 
 		if (l2tp_nl_tunnel_send(skb, NETLINK_CB(cb->skb).portid,
@@ -570,6 +583,7 @@ static int l2tp_nl_cmd_session_create(struct sk_buff *skb, struct genl_info *inf
 
 		if (info->attrs[L2TP_ATTR_COOKIE]) {
 			u16 len = nla_len(info->attrs[L2TP_ATTR_COOKIE]);
+
 			if (len > 8) {
 				ret = -EINVAL;
 				goto out_tunnel;
@@ -579,6 +593,7 @@ static int l2tp_nl_cmd_session_create(struct sk_buff *skb, struct genl_info *inf
 		}
 		if (info->attrs[L2TP_ATTR_PEER_COOKIE]) {
 			u16 len = nla_len(info->attrs[L2TP_ATTR_PEER_COOKIE]);
+
 			if (len > 8) {
 				ret = -EINVAL;
 				goto out_tunnel;
@@ -606,14 +621,13 @@ static int l2tp_nl_cmd_session_create(struct sk_buff *skb, struct genl_info *inf
 		cfg.reorder_timeout = nla_get_msecs(info->attrs[L2TP_ATTR_RECV_TIMEOUT]);
 
 #ifdef CONFIG_MODULES
-	if (l2tp_nl_cmd_ops[cfg.pw_type] == NULL) {
+	if (!l2tp_nl_cmd_ops[cfg.pw_type]) {
 		genl_unlock();
 		request_module("net-l2tp-type-%u", cfg.pw_type);
 		genl_lock();
 	}
 #endif
-	if ((l2tp_nl_cmd_ops[cfg.pw_type] == NULL) ||
-	    (l2tp_nl_cmd_ops[cfg.pw_type]->session_create == NULL)) {
+	if (!l2tp_nl_cmd_ops[cfg.pw_type] || !l2tp_nl_cmd_ops[cfg.pw_type]->session_create) {
 		ret = -EPROTONOSUPPORT;
 		goto out_tunnel;
 	}
@@ -645,7 +659,7 @@ static int l2tp_nl_cmd_session_delete(struct sk_buff *skb, struct genl_info *inf
 	u16 pw_type;
 
 	session = l2tp_nl_session_get(info);
-	if (session == NULL) {
+	if (!session) {
 		ret = -ENODEV;
 		goto out;
 	}
@@ -656,7 +670,7 @@ static int l2tp_nl_cmd_session_delete(struct sk_buff *skb, struct genl_info *inf
 	pw_type = session->pwtype;
 	if (pw_type < __L2TP_PWTYPE_MAX)
 		if (l2tp_nl_cmd_ops[pw_type] && l2tp_nl_cmd_ops[pw_type]->session_delete)
-			ret = (*l2tp_nl_cmd_ops[pw_type]->session_delete)(session);
+			l2tp_nl_cmd_ops[pw_type]->session_delete(session);
 
 	l2tp_session_dec_refcount(session);
 
@@ -670,7 +684,7 @@ static int l2tp_nl_cmd_session_modify(struct sk_buff *skb, struct genl_info *inf
 	struct l2tp_session *session;
 
 	session = l2tp_nl_session_get(info);
-	if (session == NULL) {
+	if (!session) {
 		ret = -ENODEV;
 		goto out;
 	}
@@ -715,8 +729,7 @@ static int l2tp_nl_session_send(struct sk_buff *skb, u32 portid, u32 seq, int fl
 	if (nla_put_u32(skb, L2TP_ATTR_CONN_ID, tunnel->tunnel_id) ||
 	    nla_put_u32(skb, L2TP_ATTR_SESSION_ID, session->session_id) ||
 	    nla_put_u32(skb, L2TP_ATTR_PEER_CONN_ID, tunnel->peer_tunnel_id) ||
-	    nla_put_u32(skb, L2TP_ATTR_PEER_SESSION_ID,
-			session->peer_session_id) ||
+	    nla_put_u32(skb, L2TP_ATTR_PEER_SESSION_ID, session->peer_session_id) ||
 	    nla_put_u32(skb, L2TP_ATTR_DEBUG, session->debug) ||
 	    nla_put_u16(skb, L2TP_ATTR_PW_TYPE, session->pwtype))
 		goto nla_put_failure;
@@ -724,11 +737,9 @@ static int l2tp_nl_session_send(struct sk_buff *skb, u32 portid, u32 seq, int fl
 	if ((session->ifname[0] &&
 	     nla_put_string(skb, L2TP_ATTR_IFNAME, session->ifname)) ||
 	    (session->cookie_len &&
-	     nla_put(skb, L2TP_ATTR_COOKIE, session->cookie_len,
-		     &session->cookie[0])) ||
+	     nla_put(skb, L2TP_ATTR_COOKIE, session->cookie_len, session->cookie)) ||
 	    (session->peer_cookie_len &&
-	     nla_put(skb, L2TP_ATTR_PEER_COOKIE, session->peer_cookie_len,
-		     &session->peer_cookie[0])) ||
+	     nla_put(skb, L2TP_ATTR_PEER_COOKIE, session->peer_cookie_len, session->peer_cookie)) ||
 	    nla_put_u8(skb, L2TP_ATTR_RECV_SEQ, session->recv_seq) ||
 	    nla_put_u8(skb, L2TP_ATTR_SEND_SEQ, session->send_seq) ||
 	    nla_put_u8(skb, L2TP_ATTR_LNS_MODE, session->lns_mode) ||
@@ -740,7 +751,7 @@ static int l2tp_nl_session_send(struct sk_buff *skb, u32 portid, u32 seq, int fl
 		goto nla_put_failure;
 
 	nest = nla_nest_start_noflag(skb, L2TP_ATTR_STATS);
-	if (nest == NULL)
+	if (!nest)
 		goto nla_put_failure;
 
 	if (nla_put_u64_64bit(skb, L2TP_ATTR_TX_PACKETS,
@@ -785,7 +796,7 @@ static int l2tp_nl_cmd_session_get(struct sk_buff *skb, struct genl_info *info)
 	int ret;
 
 	session = l2tp_nl_session_get(info);
-	if (session == NULL) {
+	if (!session) {
 		ret = -ENODEV;
 		goto err;
 	}
@@ -824,14 +835,14 @@ static int l2tp_nl_cmd_session_dump(struct sk_buff *skb, struct netlink_callback
 	int si = cb->args[1];
 
 	for (;;) {
-		if (tunnel == NULL) {
+		if (!tunnel) {
 			tunnel = l2tp_tunnel_get_nth(net, ti);
-			if (tunnel == NULL)
+			if (!tunnel)
 				goto out;
 		}
 
 		session = l2tp_session_get_nth(tunnel, si);
-		if (session == NULL) {
+		if (!session) {
 			ti++;
 			l2tp_tunnel_dec_refcount(tunnel);
 			tunnel = NULL;
diff --git a/net/l2tp/l2tp_ppp.c b/net/l2tp/l2tp_ppp.c
index c54cb59593ef..13c3153b40d6 100644
--- a/net/l2tp/l2tp_ppp.c
+++ b/net/l2tp/l2tp_ppp.c
@@ -117,8 +117,7 @@ struct pppol2tp_session {
 	int			owner;		/* pid that opened the socket */
 
 	struct mutex		sk_lock;	/* Protects .sk */
-	struct sock __rcu	*sk;		/* Pointer to the session
-						 * PPPoX socket */
+	struct sock __rcu	*sk;		/* Pointer to the session PPPoX socket */
 	struct sock		*__sk;		/* Copy of .sk, for cleanup */
 	struct rcu_head		rcu;		/* For asynchronous release */
 };
@@ -155,17 +154,20 @@ static inline struct l2tp_session *pppol2tp_sock_to_session(struct sock *sk)
 {
 	struct l2tp_session *session;
 
-	if (sk == NULL)
+	if (!sk)
 		return NULL;
 
 	sock_hold(sk);
 	session = (struct l2tp_session *)(sk->sk_user_data);
-	if (session == NULL) {
+	if (!session) {
+		sock_put(sk);
+		goto out;
+	}
+	if (WARN_ON(session->magic != L2TP_SESSION_MAGIC)) {
+		session = NULL;
 		sock_put(sk);
 		goto out;
 	}
-
-	BUG_ON(session->magic != L2TP_SESSION_MAGIC);
 
 out:
 	return session;
@@ -218,7 +220,7 @@ static void pppol2tp_recv(struct l2tp_session *session, struct sk_buff *skb, int
 	 */
 	rcu_read_lock();
 	sk = rcu_dereference(ps->sk);
-	if (sk == NULL)
+	if (!sk)
 		goto no_sock;
 
 	/* If the first two bytes are 0xFF03, consider that it is the PPP's
@@ -286,7 +288,7 @@ static int pppol2tp_sendmsg(struct socket *sock, struct msghdr *m,
 	/* Get session and tunnel contexts */
 	error = -EBADF;
 	session = pppol2tp_sock_to_session(sk);
-	if (session == NULL)
+	if (!session)
 		goto error;
 
 	tunnel = session->tunnel;
@@ -351,7 +353,7 @@ error:
  */
 static int pppol2tp_xmit(struct ppp_channel *chan, struct sk_buff *skb)
 {
-	struct sock *sk = (struct sock *) chan->private;
+	struct sock *sk = (struct sock *)chan->private;
 	struct l2tp_session *session;
 	struct l2tp_tunnel *tunnel;
 	int uhlen, headroom;
@@ -361,7 +363,7 @@ static int pppol2tp_xmit(struct ppp_channel *chan, struct sk_buff *skb)
 
 	/* Get session and tunnel contexts from the socket */
 	session = pppol2tp_sock_to_session(sk);
-	if (session == NULL)
+	if (!session)
 		goto abort;
 
 	tunnel = session->tunnel;
@@ -420,7 +422,8 @@ static void pppol2tp_session_destruct(struct sock *sk)
 
 	if (session) {
 		sk->sk_user_data = NULL;
-		BUG_ON(session->magic != L2TP_SESSION_MAGIC);
+		if (WARN_ON(session->magic != L2TP_SESSION_MAGIC))
+			return;
 		l2tp_session_dec_refcount(session);
 	}
 }
@@ -704,7 +707,7 @@ static int pppol2tp_connect(struct socket *sock, struct sockaddr *uservaddr,
 	 * tunnel id.
 	 */
 	if (!info.session_id && !info.peer_session_id) {
-		if (tunnel == NULL) {
+		if (!tunnel) {
 			struct l2tp_tunnel_cfg tcfg = {
 				.encap = L2TP_ENCAPTYPE_UDP,
 				.debug = 0,
@@ -739,11 +742,11 @@ static int pppol2tp_connect(struct socket *sock, struct sockaddr *uservaddr,
 	} else {
 		/* Error if we can't find the tunnel */
 		error = -ENOENT;
-		if (tunnel == NULL)
+		if (!tunnel)
 			goto end;
 
 		/* Error if socket is not prepped */
-		if (tunnel->sock == NULL)
+		if (!tunnel->sock)
 			goto end;
 	}
 
@@ -803,8 +806,7 @@ static int pppol2tp_connect(struct socket *sock, struct sockaddr *uservaddr,
 	 * the internal context for use by ioctl() and sockopt()
 	 * handlers.
 	 */
-	if ((session->session_id == 0) &&
-	    (session->peer_session_id == 0)) {
+	if (session->session_id == 0 && session->peer_session_id == 0) {
 		error = 0;
 		goto out_no_ppp;
 	}
@@ -912,22 +914,23 @@ static int pppol2tp_getname(struct socket *sock, struct sockaddr *uaddr,
 	struct pppol2tp_session *pls;
 
 	error = -ENOTCONN;
-	if (sk == NULL)
+	if (!sk)
 		goto end;
 	if (!(sk->sk_state & PPPOX_CONNECTED))
 		goto end;
 
 	error = -EBADF;
 	session = pppol2tp_sock_to_session(sk);
-	if (session == NULL)
+	if (!session)
 		goto end;
 
 	pls = l2tp_session_priv(session);
 	tunnel = session->tunnel;
 
 	inet = inet_sk(tunnel->sock);
-	if ((tunnel->version == 2) && (tunnel->sock->sk_family == AF_INET)) {
+	if (tunnel->version == 2 && tunnel->sock->sk_family == AF_INET) {
 		struct sockaddr_pppol2tp sp;
+
 		len = sizeof(sp);
 		memset(&sp, 0, len);
 		sp.sa_family	= AF_PPPOX;
@@ -943,8 +946,7 @@ static int pppol2tp_getname(struct socket *sock, struct sockaddr *uaddr,
 		sp.pppol2tp.addr.sin_addr.s_addr = inet->inet_daddr;
 		memcpy(uaddr, &sp, len);
 #if IS_ENABLED(CONFIG_IPV6)
-	} else if ((tunnel->version == 2) &&
-		   (tunnel->sock->sk_family == AF_INET6)) {
+	} else if (tunnel->version == 2 && tunnel->sock->sk_family == AF_INET6) {
 		struct sockaddr_pppol2tpin6 sp;
 
 		len = sizeof(sp);
@@ -962,8 +964,7 @@ static int pppol2tp_getname(struct socket *sock, struct sockaddr *uaddr,
 		memcpy(&sp.pppol2tp.addr.sin6_addr, &tunnel->sock->sk_v6_daddr,
 		       sizeof(tunnel->sock->sk_v6_daddr));
 		memcpy(uaddr, &sp, len);
-	} else if ((tunnel->version == 3) &&
-		   (tunnel->sock->sk_family == AF_INET6)) {
+	} else if (tunnel->version == 3 && tunnel->sock->sk_family == AF_INET6) {
 		struct sockaddr_pppol2tpv3in6 sp;
 
 		len = sizeof(sp);
@@ -984,6 +985,7 @@ static int pppol2tp_getname(struct socket *sock, struct sockaddr *uaddr,
 #endif
 	} else if (tunnel->version == 3) {
 		struct sockaddr_pppol2tpv3 sp;
+
 		len = sizeof(sp);
 		memset(&sp, 0, len);
 		sp.sa_family	= AF_PPPOX;
@@ -1178,7 +1180,7 @@ static int pppol2tp_session_setsockopt(struct sock *sk,
 
 	switch (optname) {
 	case PPPOL2TP_SO_RECVSEQ:
-		if ((val != 0) && (val != 1)) {
+		if (val != 0 && val != 1) {
 			err = -EINVAL;
 			break;
 		}
@@ -1189,7 +1191,7 @@ static int pppol2tp_session_setsockopt(struct sock *sk,
 		break;
 
 	case PPPOL2TP_SO_SENDSEQ:
-		if ((val != 0) && (val != 1)) {
+		if (val != 0 && val != 1) {
 			err = -EINVAL;
 			break;
 		}
@@ -1207,7 +1209,7 @@ static int pppol2tp_session_setsockopt(struct sock *sk,
 		break;
 
 	case PPPOL2TP_SO_LNSMODE:
-		if ((val != 0) && (val != 1)) {
+		if (val != 0 && val != 1) {
 			err = -EINVAL;
 			break;
 		}
@@ -1244,7 +1246,7 @@ static int pppol2tp_session_setsockopt(struct sock *sk,
  * session or the special tunnel type.
  */
 static int pppol2tp_setsockopt(struct socket *sock, int level, int optname,
-			       char __user *optval, unsigned int optlen)
+			       sockptr_t optval, unsigned int optlen)
 {
 	struct sock *sk = sock->sk;
 	struct l2tp_session *session;
@@ -1258,23 +1260,22 @@ static int pppol2tp_setsockopt(struct socket *sock, int level, int optname,
 	if (optlen < sizeof(int))
 		return -EINVAL;
 
-	if (get_user(val, (int __user *)optval))
+	if (copy_from_sockptr(&val, optval, sizeof(int)))
 		return -EFAULT;
 
 	err = -ENOTCONN;
-	if (sk->sk_user_data == NULL)
+	if (!sk->sk_user_data)
 		goto end;
 
 	/* Get session context from the socket */
 	err = -EBADF;
 	session = pppol2tp_sock_to_session(sk);
-	if (session == NULL)
+	if (!session)
 		goto end;
 
 	/* Special case: if session_id == 0x0000, treat as operation on tunnel
 	 */
-	if ((session->session_id == 0) &&
-	    (session->peer_session_id == 0)) {
+	if (session->session_id == 0 && session->peer_session_id == 0) {
 		tunnel = session->tunnel;
 		err = pppol2tp_tunnel_setsockopt(sk, tunnel, optname, val);
 	} else {
@@ -1343,7 +1344,7 @@ static int pppol2tp_session_getsockopt(struct sock *sk,
 		break;
 
 	case PPPOL2TP_SO_REORDERTO:
-		*val = (int) jiffies_to_msecs(session->reorder_timeout);
+		*val = (int)jiffies_to_msecs(session->reorder_timeout);
 		l2tp_info(session, L2TP_MSG_CONTROL,
 			  "%s: get reorder_timeout=%d\n", session->name, *val);
 		break;
@@ -1381,18 +1382,17 @@ static int pppol2tp_getsockopt(struct socket *sock, int level, int optname,
 		return -EINVAL;
 
 	err = -ENOTCONN;
-	if (sk->sk_user_data == NULL)
+	if (!sk->sk_user_data)
 		goto end;
 
 	/* Get the session context */
 	err = -EBADF;
 	session = pppol2tp_sock_to_session(sk);
-	if (session == NULL)
+	if (!session)
 		goto end;
 
 	/* Special case: if session_id == 0x0000, treat as operation on tunnel */
-	if ((session->session_id == 0) &&
-	    (session->peer_session_id == 0)) {
+	if (session->session_id == 0 && session->peer_session_id == 0) {
 		tunnel = session->tunnel;
 		err = pppol2tp_tunnel_getsockopt(sk, tunnel, optname, &val);
 		if (err)
@@ -1407,7 +1407,7 @@ static int pppol2tp_getsockopt(struct socket *sock, int level, int optname,
 	if (put_user(len, optlen))
 		goto end_put_sess;
 
-	if (copy_to_user((void __user *) optval, &val, len))
+	if (copy_to_user((void __user *)optval, &val, len))
 		goto end_put_sess;
 
 	err = 0;
@@ -1463,7 +1463,7 @@ static void pppol2tp_next_session(struct net *net, struct pppol2tp_seq_data *pd)
 	pd->session = l2tp_session_get_nth(pd->tunnel, pd->session_idx);
 	pd->session_idx++;
 
-	if (pd->session == NULL) {
+	if (!pd->session) {
 		pd->session_idx = 0;
 		pppol2tp_next_tunnel(net, pd);
 	}
@@ -1478,17 +1478,21 @@ static void *pppol2tp_seq_start(struct seq_file *m, loff_t *offs)
 	if (!pos)
 		goto out;
 
-	BUG_ON(m->private == NULL);
+	if (WARN_ON(!m->private)) {
+		pd = NULL;
+		goto out;
+	}
+
 	pd = m->private;
 	net = seq_file_net(m);
 
-	if (pd->tunnel == NULL)
+	if (!pd->tunnel)
 		pppol2tp_next_tunnel(net, pd);
 	else
 		pppol2tp_next_session(net, pd);
 
 	/* NULL tunnel and session indicates end of list */
-	if ((pd->tunnel == NULL) && (pd->session == NULL))
+	if (!pd->tunnel && !pd->session)
 		pd = NULL;
 
 out:
@@ -1551,6 +1555,7 @@ static void pppol2tp_seq_session_show(struct seq_file *m, void *v)
 
 	if (tunnel->sock) {
 		struct inet_sock *inet = inet_sk(tunnel->sock);
+
 		ip = ntohl(inet->inet_saddr);
 		port = ntohs(inet->inet_sport);
 	}
@@ -1564,8 +1569,7 @@ static void pppol2tp_seq_session_show(struct seq_file *m, void *v)
 		user_data_ok = 'N';
 	}
 
-	seq_printf(m, "  SESSION '%s' %08X/%d %04X/%04X -> "
-		   "%04X/%04X %d %c\n",
+	seq_printf(m, "  SESSION '%s' %08X/%d %04X/%04X -> %04X/%04X %d %c\n",
 		   session->name, ip, port,
 		   tunnel->tunnel_id,
 		   session->session_id,
@@ -1604,8 +1608,7 @@ static int pppol2tp_seq_show(struct seq_file *m, void *v)
 		seq_puts(m, "PPPoL2TP driver info, " PPPOL2TP_DRV_VERSION "\n");
 		seq_puts(m, "TUNNEL name, user-data-ok session-count\n");
 		seq_puts(m, " debug tx-pkts/bytes/errs rx-pkts/bytes/errs\n");
-		seq_puts(m, "  SESSION name, addr/port src-tid/sid "
-			 "dest-tid/sid state user-data-ok\n");
+		seq_puts(m, "  SESSION name, addr/port src-tid/sid dest-tid/sid state user-data-ok\n");
 		seq_puts(m, "   mtu/mru/rcvseq/sendseq/lns debug reorderto\n");
 		seq_puts(m, "   nr/ns tx-pkts/bytes/errs rx-pkts/bytes/errs\n");
 		goto out;
@@ -1638,7 +1641,7 @@ static __net_init int pppol2tp_init_net(struct net *net)
 	int err = 0;
 
 	pde = proc_create_net("pppol2tp", 0444, net->proc_net,
-			&pppol2tp_seq_ops, sizeof(struct pppol2tp_seq_data));
+			      &pppol2tp_seq_ops, sizeof(struct pppol2tp_seq_data));
 	if (!pde) {
 		err = -ENOMEM;
 		goto out;