Merge branch 'l2tp-misc-improvements'

James Chapman says:

====================
l2tp: misc improvements

This series makes several improvements to l2tp:

* update documentation to be consistent with recent l2tp changes.
* move l2tp_ip socket tables to per-net data.
* fix handling of hash key collisions in l2tp_v3_session_get
* implement and use get-next APIs for management and procfs/debugfs.
* improve l2tp refcount helpers.
* use per-cpu dev->tstats in l2tpeth devices.
* fix a lockdep splat.
* fix a race between l2tp_pre_exit_net and pppol2tp_release.
====================

Signed-off-by: David S. Miller <[e-mail]>

Documentation/networking/l2tp.rst

···
 L2TPv2 and 32-bit for L2TPv3. Internally, the id is stored as a 32-bit
 value.
 
-Tunnels are kept in a per-net list, indexed by tunnel id. The tunnel
-id namespace is shared by L2TPv2 and L2TPv3. The tunnel context can be
-derived from the socket's sk_user_data.
+Tunnels are kept in a per-net list, indexed by tunnel id. The
+tunnel id namespace is shared by L2TPv2 and L2TPv3.
 
 Handling tunnel socket close is perhaps the most tricky part of the
 L2TP implementation. If userspace closes a tunnel socket, the L2TP
···
 its tunnel close actions. For L2TPIP sockets, the socket's close
 handler initiates the same tunnel close actions. All sessions are
 first closed. Each session drops its tunnel ref. When the tunnel ref
-reaches zero, the tunnel puts its socket ref. When the socket is
-eventually destroyed, its sk_destruct finally frees the L2TP tunnel
-context.
+reaches zero, the tunnel drops its socket ref.
 
 Sessions
 --------
···
 Relay. Linux currently implements only Ethernet and PPP session types.
 
 Some L2TP session types also have a socket (PPP pseudowires) while
-others do not (Ethernet pseudowires). We can't therefore use the
-socket reference count as the reference count for session
-contexts. The L2TP implementation therefore has its own internal
-reference counts on the session contexts.
+others do not (Ethernet pseudowires).
 
 Like tunnels, L2TP sessions are identified by a unique
 session id. Just as with tunnel ids, the session id is 16-bit for
···
 Sessions hold a ref on their parent tunnel to ensure that the tunnel
 stays extant while one or more sessions references it.
 
-Sessions are kept in a per-tunnel list, indexed by session id. L2TPv3
-sessions are also kept in a per-net list indexed by session id,
-because L2TPv3 session ids are unique across all tunnels and L2TPv3
-data packets do not contain a tunnel id in the header. This list is
-therefore needed to find the session context associated with a
-received data packet when the tunnel context cannot be derived from
-the tunnel socket.
+Sessions are kept in a per-net list. L2TPv2 sessions and L2TPv3
+sessions are stored in separate lists. L2TPv2 sessions are keyed
+by a 32-bit key made up of the 16-bit tunnel ID and 16-bit
+session ID. L2TPv3 sessions are keyed by the 32-bit session ID, since
+L2TPv3 session ids are unique across all tunnels.
 
 Although the L2TPv3 RFC specifies that L2TPv3 session ids are not
-scoped by the tunnel, the kernel does not police this for L2TPv3 UDP
-tunnels and does not add sessions of L2TPv3 UDP tunnels into the
-per-net session list. In the UDP receive code, we must trust that the
-tunnel can be identified using the tunnel socket's sk_user_data and
-lookup the session in the tunnel's session list instead of the per-net
-session list.
+scoped by the tunnel, the Linux implementation has historically
+allowed this. Such session id collisions are supported using a per-net
+hash table keyed by sk and session ID. When looking up L2TPv3
+sessions, the list entry may link to multiple sessions with that
+session ID, in which case the session matching the given sk (tunnel)
+is used.
 
 PPP
 ---
···
 by closing its corresponding L2TP session. This is complicated because
 it must consider racing with netlink session create/destroy requests
 and pppol2tp_connect trying to reconnect with a session that is in the
-process of being closed. Unlike tunnels, PPP sessions do not hold a
-ref on their associated socket, so code must be careful to sock_hold
-the socket where necessary. For all the details, see commit
-3d609342cc04129ff7568e19316ce3d7451a27e8.
+process of being closed. PPP sessions hold a ref on their associated
+socket in order that the socket remains extants while the session
+references it.
 
 Ethernet
 --------
···
 
 The current implementation has a number of limitations:
 
-  1) Multiple UDP sockets with the same 5-tuple address cannot be
-     used. The kernel's tunnel context is identified using private
-     data associated with the socket so it is important that each
-     socket is uniquely identified by its address.
-
-  2) Interfacing with openvswitch is not yet implemented. It may be
+  1) Interfacing with openvswitch is not yet implemented. It may be
      useful to map OVS Ethernet and VLAN ports into L2TPv3 tunnels.
 
-  3) VLAN pseudowires are implemented using an ``l2tpethN`` interface
+  2) VLAN pseudowires are implemented using an ``l2tpethN`` interface
      configured with a VLAN sub-interface. Since L2TPv3 VLAN
      pseudowires carry one and only one VLAN, it may be better to use
      a single netdevice rather than an ``l2tpethN`` and ``l2tpethN``:M

net/l2tp/l2tp_core.c

···
 	struct hlist_head l2tp_v3_session_htable[16];
 };
 
-static inline u32 l2tp_v2_session_key(u16 tunnel_id, u16 session_id)
+static u32 l2tp_v2_session_key(u16 tunnel_id, u16 session_id)
 {
 	return ((u32)tunnel_id) << 16 | session_id;
 }
 
-static inline unsigned long l2tp_v3_session_hashkey(struct sock *sk, u32 session_id)
+static unsigned long l2tp_v3_session_hashkey(struct sock *sk, u32 session_id)
 {
 	return ((unsigned long)sk) + session_id;
 }
···
 }
 #endif
 
-static inline struct l2tp_net *l2tp_pernet(const struct net *net)
+static struct l2tp_net *l2tp_pernet(const struct net *net)
 {
 	return net_generic(net, l2tp_net_id);
 }
···
 {
 	trace_free_session(session);
 	if (session->tunnel)
-		l2tp_tunnel_dec_refcount(session->tunnel);
+		l2tp_tunnel_put(session->tunnel);
 	kfree_rcu(session, rcu);
 }
 
···
 }
 EXPORT_SYMBOL_GPL(l2tp_sk_to_tunnel);
 
-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)
+void l2tp_tunnel_put(struct l2tp_tunnel *tunnel)
 {
 	if (refcount_dec_and_test(&tunnel->ref_count))
 		l2tp_tunnel_free(tunnel);
 }
-EXPORT_SYMBOL_GPL(l2tp_tunnel_dec_refcount);
+EXPORT_SYMBOL_GPL(l2tp_tunnel_put);
 
-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)
+void l2tp_session_put(struct l2tp_session *session)
 {
 	if (refcount_dec_and_test(&session->ref_count))
 		l2tp_session_free(session);
 }
-EXPORT_SYMBOL_GPL(l2tp_session_dec_refcount);
+EXPORT_SYMBOL_GPL(l2tp_session_put);
 
 /* 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)
···
 }
 EXPORT_SYMBOL_GPL(l2tp_tunnel_get);
 
-struct l2tp_tunnel *l2tp_tunnel_get_nth(const struct net *net, int nth)
+struct l2tp_tunnel *l2tp_tunnel_get_next(const struct net *net, unsigned long *key)
 {
 	struct l2tp_net *pn = l2tp_pernet(net);
-	unsigned long tunnel_id, tmp;
-	struct l2tp_tunnel *tunnel;
-	int count = 0;
+	struct l2tp_tunnel *tunnel = NULL;
 
 	rcu_read_lock_bh();
-	idr_for_each_entry_ul(&pn->l2tp_tunnel_idr, tunnel, tmp, tunnel_id) {
-		if (tunnel && ++count > nth &&
-		    refcount_inc_not_zero(&tunnel->ref_count)) {
+again:
+	tunnel = idr_get_next_ul(&pn->l2tp_tunnel_idr, key);
+	if (tunnel) {
+		if (refcount_inc_not_zero(&tunnel->ref_count)) {
 			rcu_read_unlock_bh();
 			return tunnel;
 		}
+		(*key)++;
+		goto again;
 	}
 	rcu_read_unlock_bh();
 
 	return NULL;
 }
-EXPORT_SYMBOL_GPL(l2tp_tunnel_get_nth);
+EXPORT_SYMBOL_GPL(l2tp_tunnel_get_next);
 
 struct l2tp_session *l2tp_v3_session_get(const struct net *net, struct sock *sk, u32 session_id)
 {
···
 			 */
 			struct l2tp_tunnel *tunnel = READ_ONCE(session->tunnel);
 
-			if (tunnel && tunnel->sock == sk &&
+			if (session->session_id == session_id &&
+			    tunnel && tunnel->sock == sk &&
 			    refcount_inc_not_zero(&session->ref_count)) {
 				rcu_read_unlock_bh();
 				return session;
···
 }
 EXPORT_SYMBOL_GPL(l2tp_session_get);
 
-struct l2tp_session *l2tp_session_get_nth(struct l2tp_tunnel *tunnel, int nth)
+static struct l2tp_session *l2tp_v2_session_get_next(const struct net *net,
+						     u16 tid,
+						     unsigned long *key)
 {
-	struct l2tp_session *session;
-	int count = 0;
+	struct l2tp_net *pn = l2tp_pernet(net);
+	struct l2tp_session *session = NULL;
+
+	/* Start searching within the range of the tid */
+	if (*key == 0)
+		*key = l2tp_v2_session_key(tid, 0);
 
 	rcu_read_lock_bh();
-	list_for_each_entry_rcu(session, &tunnel->session_list, list) {
-		if (++count > nth) {
-			l2tp_session_inc_refcount(session);
+again:
+	session = idr_get_next_ul(&pn->l2tp_v2_session_idr, key);
+	if (session) {
+		struct l2tp_tunnel *tunnel = READ_ONCE(session->tunnel);
+
+		/* ignore sessions with id 0 as they are internal for pppol2tp */
+		if (session->session_id == 0) {
+			(*key)++;
+			goto again;
+		}
+
+		if (tunnel && tunnel->tunnel_id == tid &&
+		    refcount_inc_not_zero(&session->ref_count)) {
 			rcu_read_unlock_bh();
 			return session;
 		}
+
+		(*key)++;
+		if (tunnel->tunnel_id == tid)
+			goto again;
 	}
 	rcu_read_unlock_bh();
 
 	return NULL;
 }
-EXPORT_SYMBOL_GPL(l2tp_session_get_nth);
+
+static struct l2tp_session *l2tp_v3_session_get_next(const struct net *net,
+						     u32 tid, struct sock *sk,
+						     unsigned long *key)
+{
+	struct l2tp_net *pn = l2tp_pernet(net);
+	struct l2tp_session *session = NULL;
+
+	rcu_read_lock_bh();
+again:
+	session = idr_get_next_ul(&pn->l2tp_v3_session_idr, key);
+	if (session && !hash_hashed(&session->hlist)) {
+		struct l2tp_tunnel *tunnel = READ_ONCE(session->tunnel);
+
+		if (tunnel && tunnel->tunnel_id == tid &&
+		    refcount_inc_not_zero(&session->ref_count)) {
+			rcu_read_unlock_bh();
+			return session;
+		}
+
+		(*key)++;
+		goto again;
+	}
+
+	/* If we get here and session is non-NULL, the IDR entry may be one
+	 * where the session_id collides with one in another tunnel. Check
+	 * session_htable for a match. There can only be one session of a given
+	 * ID per tunnel so we can return as soon as a match is found.
+	 */
+	if (session && hash_hashed(&session->hlist)) {
+		unsigned long hkey = l2tp_v3_session_hashkey(sk, session->session_id);
+		u32 sid = session->session_id;
+
+		hash_for_each_possible_rcu(pn->l2tp_v3_session_htable, session,
+					   hlist, hkey) {
+			struct l2tp_tunnel *tunnel = READ_ONCE(session->tunnel);
+
+			if (session->session_id == sid &&
+			    tunnel && tunnel->tunnel_id == tid &&
+			    refcount_inc_not_zero(&session->ref_count)) {
+				rcu_read_unlock_bh();
+				return session;
+			}
+		}
+
+		/* If no match found, the colliding session ID isn't in our
+		 * tunnel so try the next session ID.
+		 */
+		(*key)++;
+		goto again;
+	}
+
+	rcu_read_unlock_bh();
+
+	return NULL;
+}
+
+struct l2tp_session *l2tp_session_get_next(const struct net *net, struct sock *sk, int pver,
+					   u32 tunnel_id, unsigned long *key)
+{
+	if (pver == L2TP_HDR_VER_2)
+		return l2tp_v2_session_get_next(net, tunnel_id, key);
+	else
+		return l2tp_v3_session_get_next(net, tunnel_id, sk, key);
+}
+EXPORT_SYMBOL_GPL(l2tp_session_get_next);
 
 /* Lookup a session by interface name.
  * This is very inefficient but is only used by management interfaces.
···
 		if (tunnel) {
 			list_for_each_entry_rcu(session, &tunnel->session_list, list) {
 				if (!strcmp(session->ifname, ifname)) {
-					l2tp_session_inc_refcount(session);
+					refcount_inc(&session->ref_count);
 					rcu_read_unlock_bh();
 
 					return session;
···
 static void l2tp_session_coll_list_add(struct l2tp_session_coll_list *clist,
 				       struct l2tp_session *session)
 {
-	l2tp_session_inc_refcount(session);
+	refcount_inc(&session->ref_count);
 	WARN_ON_ONCE(session->coll_list);
 	session->coll_list = clist;
 	spin_lock(&clist->lock);
···
 		spin_unlock(&clist->lock);
 		if (refcount_dec_and_test(&clist->ref_count))
 			kfree(clist);
-		l2tp_session_dec_refcount(session);
+		l2tp_session_put(session);
 	}
 }
 
···
 		goto out;
 	}
 
-	l2tp_tunnel_inc_refcount(tunnel);
+	refcount_inc(&tunnel->ref_count);
 	WRITE_ONCE(session->tunnel, tunnel);
 	list_add_rcu(&session->list, &tunnel->session_list);
 
···
 
 	if (!session || !session->recv_skb) {
 		if (session)
-			l2tp_session_dec_refcount(session);
+			l2tp_session_put(session);
 
 		/* Not found? Pass to userspace to deal with */
 		goto pass;
···
 
 	if (version == L2TP_HDR_VER_3 &&
 	    l2tp_v3_ensure_opt_in_linear(session, skb, &ptr, &optr)) {
-		l2tp_session_dec_refcount(session);
+		l2tp_session_put(session);
 		goto invalid;
 	}
 
 	l2tp_recv_common(session, skb, ptr, optr, hdrflags, length);
-	l2tp_session_dec_refcount(session);
+	l2tp_session_put(session);
 
 	return 0;
 
···
 	tunnel = l2tp_sk_to_tunnel(sk);
 	if (tunnel) {
 		l2tp_tunnel_delete(tunnel);
-		l2tp_tunnel_dec_refcount(tunnel);
+		l2tp_tunnel_put(tunnel);
 	}
 }
 
···
 
 	l2tp_tunnel_remove(tunnel->l2tp_net, tunnel);
 	/* drop initial ref */
-	l2tp_tunnel_dec_refcount(tunnel);
+	l2tp_tunnel_put(tunnel);
 
 	/* drop workqueue ref */
-	l2tp_tunnel_dec_refcount(tunnel);
+	l2tp_tunnel_put(tunnel);
 }
 
 /* Create a socket for the tunnel, if one isn't set up by
···
 
 	tunnel = l2tp_sk_to_tunnel(sk);
 	if (tunnel) {
-		l2tp_tunnel_dec_refcount(tunnel);
+		l2tp_tunnel_put(tunnel);
 		return -EBUSY;
 	}
 
···
 {
 	if (!test_and_set_bit(0, &tunnel->dead)) {
 		trace_delete_tunnel(tunnel);
-		l2tp_tunnel_inc_refcount(tunnel);
+		refcount_inc(&tunnel->ref_count);
 		queue_work(l2tp_wq, &tunnel->del_work);
 	}
 }
···
 {
 	if (!test_and_set_bit(0, &session->dead)) {
 		trace_delete_session(session);
-		l2tp_session_inc_refcount(session);
+		refcount_inc(&session->ref_count);
 		queue_work(l2tp_wq, &session->del_work);
 	}
 }
···
 		(*session->session_close)(session);
 
 	/* drop initial ref */
-	l2tp_session_dec_refcount(session);
+	l2tp_session_put(session);
 
 	/* drop workqueue ref */
-	l2tp_session_dec_refcount(session);
+	l2tp_session_put(session);
 }
 
 /* We come here whenever a session's send_seq, cookie_len or
···
 	}
 	rcu_read_unlock_bh();
 
-	if (l2tp_wq)
+	if (l2tp_wq) {
+		/* ensure that all TUNNEL_DELETE work items are run before
+		 * draining the work queue since TUNNEL_DELETE requests may
+		 * queue SESSION_DELETE work items for each session in the
+		 * tunnel. drain_workqueue may otherwise warn if SESSION_DELETE
+		 * requests are queued while the work queue is being drained.
+		 */
+		__flush_workqueue(l2tp_wq);
 		drain_workqueue(l2tp_wq);
+	}
 }
 
 static __net_exit void l2tp_exit_net(struct net *net)

net/l2tp/l2tp_core.h

···
 }
 
 /* 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);
+void l2tp_tunnel_put(struct l2tp_tunnel *tunnel);
+void l2tp_session_put(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_tunnel *l2tp_tunnel_get_next(const struct net *net, unsigned long *key);
 
 struct l2tp_session *l2tp_v3_session_get(const struct net *net, struct sock *sk, u32 session_id);
 struct l2tp_session *l2tp_v2_session_get(const struct net *net, u16 tunnel_id, u16 session_id);
 struct l2tp_session *l2tp_session_get(const struct net *net, struct sock *sk, int pver,
 				      u32 tunnel_id, u32 session_id);
-struct l2tp_session *l2tp_session_get_nth(struct l2tp_tunnel *tunnel, int nth);
+struct l2tp_session *l2tp_session_get_next(const struct net *net, struct sock *sk, int pver,
+					   u32 tunnel_id, unsigned long *key);
 struct l2tp_session *l2tp_session_get_by_ifname(const struct net *net,
 						const char *ifname);
 

net/l2tp/l2tp_debugfs.c

···
 struct l2tp_dfs_seq_data {
 	struct net	*net;
 	netns_tracker	ns_tracker;
-	int tunnel_idx;			/* current tunnel */
-	int session_idx;		/* index of session within current tunnel */
+	unsigned long tkey;		/* lookup key of current tunnel */
+	unsigned long skey;		/* lookup key of current session */
 	struct l2tp_tunnel *tunnel;
 	struct l2tp_session *session;	/* NULL means get next tunnel */
 };
···
 {
 	/* Drop reference taken during previous invocation */
 	if (pd->tunnel)
-		l2tp_tunnel_dec_refcount(pd->tunnel);
+		l2tp_tunnel_put(pd->tunnel);
 
-	pd->tunnel = l2tp_tunnel_get_nth(pd->net, pd->tunnel_idx);
-	pd->tunnel_idx++;
+	pd->tunnel = l2tp_tunnel_get_next(pd->net, &pd->tkey);
+	pd->tkey++;
 }
 
 static void l2tp_dfs_next_session(struct l2tp_dfs_seq_data *pd)
 {
 	/* Drop reference taken during previous invocation */
 	if (pd->session)
-		l2tp_session_dec_refcount(pd->session);
+		l2tp_session_put(pd->session);
 
-	pd->session = l2tp_session_get_nth(pd->tunnel, pd->session_idx);
-	pd->session_idx++;
+	pd->session = l2tp_session_get_next(pd->net, pd->tunnel->sock,
+					    pd->tunnel->version,
+					    pd->tunnel->tunnel_id, &pd->skey);
+	pd->skey++;
 
 	if (!pd->session) {
-		pd->session_idx = 0;
+		pd->skey = 0;
 		l2tp_dfs_next_tunnel(pd);
 	}
 }
···
 	 * or l2tp_dfs_next_tunnel().
 	 */
 	if (pd->session) {
-		l2tp_session_dec_refcount(pd->session);
+		l2tp_session_put(pd->session);
 		pd->session = NULL;
 	}
 	if (pd->tunnel) {
-		l2tp_tunnel_dec_refcount(pd->tunnel);
+		l2tp_tunnel_put(pd->tunnel);
 		pd->tunnel = NULL;
 	}
 }

net/l2tp/l2tp_eth.c

···
 	unsigned int len = skb->len;
 	int ret = l2tp_xmit_skb(session, skb);
 
-	if (likely(ret == NET_XMIT_SUCCESS)) {
-		DEV_STATS_ADD(dev, tx_bytes, len);
-		DEV_STATS_INC(dev, tx_packets);
-	} else {
+	if (likely(ret == NET_XMIT_SUCCESS))
+		dev_sw_netstats_tx_add(dev, 1, len);
+	else
 		DEV_STATS_INC(dev, tx_dropped);
-	}
-	return NETDEV_TX_OK;
-}
 
-static void l2tp_eth_get_stats64(struct net_device *dev,
-				 struct rtnl_link_stats64 *stats)
-{
-	stats->tx_bytes   = DEV_STATS_READ(dev, tx_bytes);
-	stats->tx_packets = DEV_STATS_READ(dev, tx_packets);
-	stats->tx_dropped = DEV_STATS_READ(dev, tx_dropped);
-	stats->rx_bytes   = DEV_STATS_READ(dev, rx_bytes);
-	stats->rx_packets = DEV_STATS_READ(dev, rx_packets);
-	stats->rx_errors  = DEV_STATS_READ(dev, rx_errors);
+	return NETDEV_TX_OK;
 }
 
 static const struct net_device_ops l2tp_eth_netdev_ops = {
 	.ndo_init		= l2tp_eth_dev_init,
 	.ndo_uninit		= l2tp_eth_dev_uninit,
 	.ndo_start_xmit		= l2tp_eth_dev_xmit,
-	.ndo_get_stats64	= l2tp_eth_get_stats64,
+	.ndo_get_stats64	= dev_get_tstats64,
 	.ndo_set_mac_address	= eth_mac_addr,
 };
 
···
 	dev->features		|= NETIF_F_LLTX;
 	dev->netdev_ops		= &l2tp_eth_netdev_ops;
 	dev->needs_free_netdev	= true;
+	dev->pcpu_stat_type	= NETDEV_PCPU_STAT_TSTATS;
 }
 
 static void l2tp_eth_dev_recv(struct l2tp_session *session, struct sk_buff *skb, int data_len)
···
 	if (!dev)
 		goto error_rcu;
 
-	if (dev_forward_skb(dev, skb) == NET_RX_SUCCESS) {
-		DEV_STATS_INC(dev, rx_packets);
-		DEV_STATS_ADD(dev, rx_bytes, data_len);
-	} else {
+	if (dev_forward_skb(dev, skb) == NET_RX_SUCCESS)
+		dev_sw_netstats_rx_add(dev, data_len);
+	else
 		DEV_STATS_INC(dev, rx_errors);
-	}
+
 	rcu_read_unlock();
 
 	return;
···
 
 	spriv = l2tp_session_priv(session);
 
-	l2tp_session_inc_refcount(session);
+	refcount_inc(&session->ref_count);
 
 	rtnl_lock();
 
···
 	if (rc < 0) {
 		rtnl_unlock();
 		l2tp_session_delete(session);
-		l2tp_session_dec_refcount(session);
+		l2tp_session_put(session);
 		free_netdev(dev);
 
 		return rc;
···
 
 	rtnl_unlock();
 
-	l2tp_session_dec_refcount(session);
+	l2tp_session_put(session);
 
 	__module_get(THIS_MODULE);
 
 	return 0;
 
 err_sess_dev:
-	l2tp_session_dec_refcount(session);
+	l2tp_session_put(session);
 	free_netdev(dev);
 err_sess:
-	l2tp_session_dec_refcount(session);
+	l2tp_session_put(session);
 err:
 	return rc;
 }

net/l2tp/l2tp_ip.c

···
 #include <net/tcp_states.h>
 #include <net/protocol.h>
 #include <net/xfrm.h>
+#include <net/net_namespace.h>
+#include <net/netns/generic.h>
 
 #include "l2tp_core.h"
+
+/* per-net private data for this module */
+static unsigned int l2tp_ip_net_id;
+struct l2tp_ip_net {
+	rwlock_t l2tp_ip_lock;
+	struct hlist_head l2tp_ip_table;
+	struct hlist_head l2tp_ip_bind_table;
+};
 
 struct l2tp_ip_sock {
 	/* inet_sock has to be the first member of l2tp_ip_sock */
···
 	u32			peer_conn_id;
 };
 
-static DEFINE_RWLOCK(l2tp_ip_lock);
-static struct hlist_head l2tp_ip_table;
-static struct hlist_head l2tp_ip_bind_table;
-
-static inline struct l2tp_ip_sock *l2tp_ip_sk(const struct sock *sk)
+static struct l2tp_ip_sock *l2tp_ip_sk(const struct sock *sk)
 {
 	return (struct l2tp_ip_sock *)sk;
+}
+
+static struct l2tp_ip_net *l2tp_ip_pernet(const struct net *net)
+{
+	return net_generic(net, l2tp_ip_net_id);
 }
 
 static struct sock *__l2tp_ip_bind_lookup(const struct net *net, __be32 laddr,
 					  __be32 raddr, int dif, u32 tunnel_id)
 {
+	struct l2tp_ip_net *pn = l2tp_ip_pernet(net);
 	struct sock *sk;
 
-	sk_for_each_bound(sk, &l2tp_ip_bind_table) {
+	sk_for_each_bound(sk, &pn->l2tp_ip_bind_table) {
 		const struct l2tp_ip_sock *l2tp = l2tp_ip_sk(sk);
 		const struct inet_sock *inet = inet_sk(sk);
 		int bound_dev_if;
···
 static int l2tp_ip_recv(struct sk_buff *skb)
 {
 	struct net *net = dev_net(skb->dev);
+	struct l2tp_ip_net *pn;
 	struct sock *sk;
 	u32 session_id;
 	u32 tunnel_id;
···
 	struct l2tp_session *session;
 	struct l2tp_tunnel *tunnel = NULL;
 	struct iphdr *iph;
+
+	pn = l2tp_ip_pernet(net);
 
 	if (!pskb_may_pull(skb, 4))
 		goto discard;
···
 		goto discard_sess;
 
 	l2tp_recv_common(session, skb, ptr, optr, 0, skb->len);
-	l2tp_session_dec_refcount(session);
+	l2tp_session_put(session);
 
 	return 0;
 
···
 	tunnel_id = ntohl(*(__be32 *)&skb->data[4]);
 	iph = (struct iphdr *)skb_network_header(skb);
 
-	read_lock_bh(&l2tp_ip_lock);
+	read_lock_bh(&pn->l2tp_ip_lock);
 	sk = __l2tp_ip_bind_lookup(net, iph->daddr, iph->saddr, inet_iif(skb),
 				   tunnel_id);
 	if (!sk) {
-		read_unlock_bh(&l2tp_ip_lock);
+		read_unlock_bh(&pn->l2tp_ip_lock);
 		goto discard;
 	}
 	sock_hold(sk);
-	read_unlock_bh(&l2tp_ip_lock);
+	read_unlock_bh(&pn->l2tp_ip_lock);
 
 	if (!xfrm4_policy_check(sk, XFRM_POLICY_IN, skb))
 		goto discard_put;
···
 	return sk_receive_skb(sk, skb, 1);
 
 discard_sess:
-	l2tp_session_dec_refcount(session);
+	l2tp_session_put(session);
 	goto discard;
 
 discard_put:
···
 
 static int l2tp_ip_hash(struct sock *sk)
 {
+	struct l2tp_ip_net *pn = l2tp_ip_pernet(sock_net(sk));
+
 	if (sk_unhashed(sk)) {
-		write_lock_bh(&l2tp_ip_lock);
-		sk_add_node(sk, &l2tp_ip_table);
-		write_unlock_bh(&l2tp_ip_lock);
+		write_lock_bh(&pn->l2tp_ip_lock);
+		sk_add_node(sk, &pn->l2tp_ip_table);
+		write_unlock_bh(&pn->l2tp_ip_lock);
 	}
 	return 0;
 }
 
 static void l2tp_ip_unhash(struct sock *sk)
 {
+	struct l2tp_ip_net *pn = l2tp_ip_pernet(sock_net(sk));
+
 	if (sk_unhashed(sk))
 		return;
-	write_lock_bh(&l2tp_ip_lock);
+	write_lock_bh(&pn->l2tp_ip_lock);
 	sk_del_node_init(sk);
-	write_unlock_bh(&l2tp_ip_lock);
+	write_unlock_bh(&pn->l2tp_ip_lock);
 }
 
 static int l2tp_ip_open(struct sock *sk)
···
 
 static void l2tp_ip_close(struct sock *sk, long timeout)
 {
-	write_lock_bh(&l2tp_ip_lock);
+	struct l2tp_ip_net *pn = l2tp_ip_pernet(sock_net(sk));
+
+	write_lock_bh(&pn->l2tp_ip_lock);
 	hlist_del_init(&sk->sk_bind_node);
 	sk_del_node_init(sk);
-	write_unlock_bh(&l2tp_ip_lock);
+	write_unlock_bh(&pn->l2tp_ip_lock);
 	sk_common_release(sk);
 }
 
···
 	tunnel = l2tp_sk_to_tunnel(sk);
 	if (tunnel) {
 		l2tp_tunnel_delete(tunnel);
-		l2tp_tunnel_dec_refcount(tunnel);
+		l2tp_tunnel_put(tunnel);
 	}
 }
 
···
 	struct inet_sock *inet = inet_sk(sk);
 	struct sockaddr_l2tpip *addr = (struct sockaddr_l2tpip *)uaddr;
 	struct net *net = sock_net(sk);
+	struct l2tp_ip_net *pn;
 	int ret;
 	int chk_addr_ret;
 
···
 	if (chk_addr_ret == RTN_MULTICAST || chk_addr_ret == RTN_BROADCAST)
 		inet->inet_saddr = 0;  /* Use device */
 
-	write_lock_bh(&l2tp_ip_lock);
+	pn = l2tp_ip_pernet(net);
+	write_lock_bh(&pn->l2tp_ip_lock);
 	if (__l2tp_ip_bind_lookup(net, addr->l2tp_addr.s_addr, 0,
 				  sk->sk_bound_dev_if, addr->l2tp_conn_id)) {
-		write_unlock_bh(&l2tp_ip_lock);
+		write_unlock_bh(&pn->l2tp_ip_lock);
 		ret = -EADDRINUSE;
 		goto out;
 	}
···
 	sk_dst_reset(sk);
 	l2tp_ip_sk(sk)->conn_id = addr->l2tp_conn_id;
 
-	sk_add_bind_node(sk, &l2tp_ip_bind_table);
+	sk_add_bind_node(sk, &pn->l2tp_ip_bind_table);
 	sk_del_node_init(sk);
-	write_unlock_bh(&l2tp_ip_lock);
+	write_unlock_bh(&pn->l2tp_ip_lock);
 
 	ret = 0;
 	sock_reset_flag(sk, SOCK_ZAPPED);
···
 static int l2tp_ip_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
 {
 	struct sockaddr_l2tpip *lsa = (struct sockaddr_l2tpip *)uaddr;
+	struct l2tp_ip_net *pn = l2tp_ip_pernet(sock_net(sk));
 	int rc;
 
 	if (addr_len < sizeof(*lsa))
···
 
 	l2tp_ip_sk(sk)->peer_conn_id = lsa->l2tp_conn_id;
 
-	write_lock_bh(&l2tp_ip_lock);
+	write_lock_bh(&pn->l2tp_ip_lock);
 	hlist_del_init(&sk->sk_bind_node);
-	sk_add_bind_node(sk, &l2tp_ip_bind_table);
-	write_unlock_bh(&l2tp_ip_lock);
+	sk_add_bind_node(sk, &pn->l2tp_ip_bind_table);
+	write_unlock_bh(&pn->l2tp_ip_lock);
 
 out_sk:
 	release_sock(sk);
···
 	.handler	= l2tp_ip_recv,
 };
 
+static __net_init int l2tp_ip_init_net(struct net *net)
+{
+	struct l2tp_ip_net *pn = net_generic(net, l2tp_ip_net_id);
+
+	rwlock_init(&pn->l2tp_ip_lock);
+	INIT_HLIST_HEAD(&pn->l2tp_ip_table);
+	INIT_HLIST_HEAD(&pn->l2tp_ip_bind_table);
+	return 0;
+}
+
+static __net_exit void l2tp_ip_exit_net(struct net *net)
+{
+	struct l2tp_ip_net *pn = l2tp_ip_pernet(net);
+
+	write_lock_bh(&pn->l2tp_ip_lock);
+	WARN_ON_ONCE(hlist_count_nodes(&pn->l2tp_ip_table) != 0);
+	WARN_ON_ONCE(hlist_count_nodes(&pn->l2tp_ip_bind_table) != 0);
+	write_unlock_bh(&pn->l2tp_ip_lock);
+}
+
+static struct pernet_operations l2tp_ip_net_ops = {
+	.init = l2tp_ip_init_net,
+	.exit = l2tp_ip_exit_net,
+	.id   = &l2tp_ip_net_id,
+	.size = sizeof(struct l2tp_ip_net),
+};
+
 static int __init l2tp_ip_init(void)
 {
 	int err;
 
 	pr_info("L2TP IP encapsulation support (L2TPv3)\n");
 
+	err = register_pernet_device(&l2tp_ip_net_ops);
+	if (err)
+		goto out;
+
 	err = proto_register(&l2tp_ip_prot, 1);
 	if (err != 0)
-		goto out;
+		goto out1;
 
 	err = inet_add_protocol(&l2tp_ip_protocol, IPPROTO_L2TP);
 	if (err)
-		goto out1;
+		goto out2;
 
 	inet_register_protosw(&l2tp_ip_protosw);
 	return 0;
 
-out1:
+out2:
 	proto_unregister(&l2tp_ip_prot);
+out1:
+	unregister_pernet_device(&l2tp_ip_net_ops);
 out:
 	return err;
 }
···
 	inet_unregister_protosw(&l2tp_ip_protosw);
 	inet_del_protocol(&l2tp_ip_protocol, IPPROTO_L2TP);
 	proto_unregister(&l2tp_ip_prot);
+	unregister_pernet_device(&l2tp_ip_net_ops);
 }
 
 module_init(l2tp_ip_init);

net/l2tp/l2tp_ip6.c

···
 #include <net/tcp_states.h>
 #include <net/protocol.h>
 #include <net/xfrm.h>
+#include <net/net_namespace.h>
+#include <net/netns/generic.h>
 
 #include <net/transp_v6.h>
 #include <net/addrconf.h>
 #include <net/ip6_route.h>
 
 #include "l2tp_core.h"
+
+/* per-net private data for this module */
+static unsigned int l2tp_ip6_net_id;
+struct l2tp_ip6_net {
+	rwlock_t l2tp_ip6_lock;
+	struct hlist_head l2tp_ip6_table;
+	struct hlist_head l2tp_ip6_bind_table;
+};
 
 struct l2tp_ip6_sock {
 	/* inet_sock has to be the first member of l2tp_ip6_sock */
···
 	struct ipv6_pinfo	inet6;
 };
 
-static DEFINE_RWLOCK(l2tp_ip6_lock);
-static struct hlist_head l2tp_ip6_table;
-static struct hlist_head l2tp_ip6_bind_table;
-
-static inline struct l2tp_ip6_sock *l2tp_ip6_sk(const struct sock *sk)
+static struct l2tp_ip6_sock *l2tp_ip6_sk(const struct sock *sk)
 {
 	return (struct l2tp_ip6_sock *)sk;
+}
+
+static struct l2tp_ip6_net *l2tp_ip6_pernet(const struct net *net)
+{
+	return net_generic(net, l2tp_ip6_net_id);
 }
 
 static struct sock *__l2tp_ip6_bind_lookup(const struct net *net,
···
 					   const struct in6_addr *raddr,
 					   int dif, u32 tunnel_id)
 {
+	struct l2tp_ip6_net *pn = l2tp_ip6_pernet(net);
 	struct sock *sk;
 
-	sk_for_each_bound(sk, &l2tp_ip6_bind_table) {
+	sk_for_each_bound(sk, &pn->l2tp_ip6_bind_table) {
 		const struct in6_addr *sk_laddr = inet6_rcv_saddr(sk);
 		const struct in6_addr *sk_raddr = &sk->sk_v6_daddr;
 		const struct l2tp_ip6_sock *l2tp = l2tp_ip6_sk(sk);
···
 static int l2tp_ip6_recv(struct sk_buff *skb)
 {
 	struct net *net = dev_net(skb->dev);
+	struct l2tp_ip6_net *pn;
 	struct sock *sk;
 	u32 session_id;
 	u32 tunnel_id;
···
 	struct l2tp_session *session;
 	struct l2tp_tunnel *tunnel = NULL;
 	struct ipv6hdr *iph;
+
+	pn = l2tp_ip6_pernet(net);
 
 	if (!pskb_may_pull(skb, 4))
 		goto discard;
···
 		goto discard_sess;
 
 	l2tp_recv_common(session, skb, ptr, optr, 0, skb->len);
-	l2tp_session_dec_refcount(session);
+	l2tp_session_put(session);
 
 	return 0;
 
···
 	tunnel_id = ntohl(*(__be32 *)&skb->data[4]);
 	iph = ipv6_hdr(skb);
 
-	read_lock_bh(&l2tp_ip6_lock);
+	read_lock_bh(&pn->l2tp_ip6_lock);
 	sk = __l2tp_ip6_bind_lookup(net, &iph->daddr, &iph->saddr,
 				    inet6_iif(skb), tunnel_id);
 	if (!sk) {
-		read_unlock_bh(&l2tp_ip6_lock);
+		read_unlock_bh(&pn->l2tp_ip6_lock);
 		goto discard;
 	}
 	sock_hold(sk);
-	read_unlock_bh(&l2tp_ip6_lock);
+	read_unlock_bh(&pn->l2tp_ip6_lock);
 
 	if (!xfrm6_policy_check(sk, XFRM_POLICY_IN, skb))
 		goto discard_put;
···
 	return sk_receive_skb(sk, skb, 1);
 
 discard_sess:
-	l2tp_session_dec_refcount(session);
+	l2tp_session_put(session);
 	goto discard;
 
 discard_put:
···
 
 static int l2tp_ip6_hash(struct sock *sk)
 {
+	struct l2tp_ip6_net *pn = l2tp_ip6_pernet(sock_net(sk));
+
 	if (sk_unhashed(sk)) {
-		write_lock_bh(&l2tp_ip6_lock);
-		sk_add_node(sk, &l2tp_ip6_table);
-		write_unlock_bh(&l2tp_ip6_lock);
+		write_lock_bh(&pn->l2tp_ip6_lock);
+		sk_add_node(sk, &pn->l2tp_ip6_table);
+		write_unlock_bh(&pn->l2tp_ip6_lock);
 	}
 	return 0;
 }
 
 static void l2tp_ip6_unhash(struct sock *sk)
 {
+	struct l2tp_ip6_net *pn = l2tp_ip6_pernet(sock_net(sk));
+
 	if (sk_unhashed(sk))
 		return;
-	write_lock_bh(&l2tp_ip6_lock);
+	write_lock_bh(&pn->l2tp_ip6_lock);
 	sk_del_node_init(sk);
-	write_unlock_bh(&l2tp_ip6_lock);
+	write_unlock_bh(&pn->l2tp_ip6_lock);
 }
 
 static int l2tp_ip6_open(struct sock *sk)
···
 
 static void l2tp_ip6_close(struct sock *sk, long timeout)
 {
-	write_lock_bh(&l2tp_ip6_lock);
+	struct l2tp_ip6_net *pn = l2tp_ip6_pernet(sock_net(sk));
+
+	write_lock_bh(&pn->l2tp_ip6_lock);
 	hlist_del_init(&sk->sk_bind_node);
 	sk_del_node_init(sk);
-	write_unlock_bh(&l2tp_ip6_lock);
+	write_unlock_bh(&pn->l2tp_ip6_lock);
 
 	sk_common_release(sk);
 }
···
 	tunnel = l2tp_sk_to_tunnel(sk);
 	if (tunnel) {
 		l2tp_tunnel_delete(tunnel);
-		l2tp_tunnel_dec_refcount(tunnel);
+		l2tp_tunnel_put(tunnel);
 	}
 }
 
···
 	struct ipv6_pinfo *np = inet6_sk(sk);
 	struct sockaddr_l2tpip6 *addr = (struct sockaddr_l2tpip6 *)uaddr;
 	struct net *net = sock_net(sk);
+	struct l2tp_ip6_net *pn;
 	__be32 v4addr = 0;
 	int bound_dev_if;
 	int addr_type;
 	int err;
+
+	pn = l2tp_ip6_pernet(net);
 
 	if (addr->l2tp_family != AF_INET6)
 		return -EINVAL;
···
 	}
 	rcu_read_unlock();
 
-	write_lock_bh(&l2tp_ip6_lock);
+	write_lock_bh(&pn->l2tp_ip6_lock);
 	if (__l2tp_ip6_bind_lookup(net, &addr->l2tp_addr, NULL, bound_dev_if,
 				   addr->l2tp_conn_id)) {
-		write_unlock_bh(&l2tp_ip6_lock);
+		write_unlock_bh(&pn->l2tp_ip6_lock);
 		err = -EADDRINUSE;
 		goto out_unlock;
 	}
···
 
 	l2tp_ip6_sk(sk)->conn_id = addr->l2tp_conn_id;
 
-	sk_add_bind_node(sk, &l2tp_ip6_bind_table);
+	sk_add_bind_node(sk, &pn->l2tp_ip6_bind_table);
 	sk_del_node_init(sk);
-	write_unlock_bh(&l2tp_ip6_lock);
+	write_unlock_bh(&pn->l2tp_ip6_lock);
 
 	sock_reset_flag(sk, SOCK_ZAPPED);
 	release_sock(sk);
···
 	struct in6_addr	*daddr;
 	int	addr_type;
 	int rc;
+	struct l2tp_ip6_net *pn;
 
 	if (addr_len < sizeof(*lsa))
 		return -EINVAL;
···
 
 	l2tp_ip6_sk(sk)->peer_conn_id = lsa->l2tp_conn_id;
 
-	write_lock_bh(&l2tp_ip6_lock);
+	pn = l2tp_ip6_pernet(sock_net(sk));
+	write_lock_bh(&pn->l2tp_ip6_lock);
 	hlist_del_init(&sk->sk_bind_node);
-	sk_add_bind_node(sk, &l2tp_ip6_bind_table);
-	write_unlock_bh(&l2tp_ip6_lock);
+	sk_add_bind_node(sk, &pn->l2tp_ip6_bind_table);
+	write_unlock_bh(&pn->l2tp_ip6_lock);
 
 out_sk:
 	release_sock(sk);
···
 	.handler	= l2tp_ip6_recv,
 };
 
+static __net_init int l2tp_ip6_init_net(struct net *net)
+{
+	struct l2tp_ip6_net *pn = net_generic(net, l2tp_ip6_net_id);
+
+	rwlock_init(&pn->l2tp_ip6_lock);
+	INIT_HLIST_HEAD(&pn->l2tp_ip6_table);
+	INIT_HLIST_HEAD(&pn->l2tp_ip6_bind_table);
+	return 0;
+}
+
+static __net_exit void l2tp_ip6_exit_net(struct net *net)
+{
+	struct l2tp_ip6_net *pn = l2tp_ip6_pernet(net);
+
+	write_lock_bh(&pn->l2tp_ip6_lock);
+	WARN_ON_ONCE(hlist_count_nodes(&pn->l2tp_ip6_table) != 0);
+	WARN_ON_ONCE(hlist_count_nodes(&pn->l2tp_ip6_bind_table) != 0);
+	write_unlock_bh(&pn->l2tp_ip6_lock);
+}
+
+static struct pernet_operations l2tp_ip6_net_ops = {
+	.init = l2tp_ip6_init_net,
+	.exit = l2tp_ip6_exit_net,
+	.id   = &l2tp_ip6_net_id,
+	.size = sizeof(struct l2tp_ip6_net),
+};
+
 static int __init l2tp_ip6_init(void)
 {
 	int err;
 
 	pr_info("L2TP IP encapsulation support for IPv6 (L2TPv3)\n");
 
+	err = register_pernet_device(&l2tp_ip6_net_ops);
+	if (err)
+		goto out;
+
 	err = proto_register(&l2tp_ip6_prot, 1);
 	if (err != 0)
-		goto out;
+		goto out1;
 
 	err = inet6_add_protocol(&l2tp_ip6_protocol, IPPROTO_L2TP);
 	if (err)
-		goto out1;
+		goto out2;
 
 	inet6_register_protosw(&l2tp_ip6_protosw);
 	return 0;
 
-out1:
+out2:
 	proto_unregister(&l2tp_ip6_prot);
+out1:
+	unregister_pernet_device(&l2tp_ip6_net_ops);
 out:
 	return err;
 }
···
 	inet6_unregister_protosw(&l2tp_ip6_protosw);
 	inet6_del_protocol(&l2tp_ip6_protocol, IPPROTO_L2TP);
 	proto_unregister(&l2tp_ip6_prot);
+	unregister_pernet_device(&l2tp_ip6_net_ops);
 }
 
 module_init(l2tp_ip6_init);

net/l2tp/l2tp_netlink.c

···
 		if (tunnel) {
 			session = l2tp_session_get(net, tunnel->sock, tunnel->version,
 						   tunnel_id, session_id);
-			l2tp_tunnel_dec_refcount(tunnel);
+			l2tp_tunnel_put(tunnel);
 		}
 	}
 
···
 	if (ret < 0)
 		goto out;
 
-	l2tp_tunnel_inc_refcount(tunnel);
+	refcount_inc(&tunnel->ref_count);
 	ret = l2tp_tunnel_register(tunnel, net, &cfg);
 	if (ret < 0) {
 		kfree(tunnel);
···
 	}
 	ret = l2tp_tunnel_notify(&l2tp_nl_family, info, tunnel,
 				 L2TP_CMD_TUNNEL_CREATE);
-	l2tp_tunnel_dec_refcount(tunnel);
+	l2tp_tunnel_put(tunnel);
 
 out:
 	return ret;
···
 
 	l2tp_tunnel_delete(tunnel);
 
-	l2tp_tunnel_dec_refcount(tunnel);
+	l2tp_tunnel_put(tunnel);
 
 out:
 	return ret;
···
 	ret = l2tp_tunnel_notify(&l2tp_nl_family, info,
 				 tunnel, L2TP_CMD_TUNNEL_MODIFY);
 
-	l2tp_tunnel_dec_refcount(tunnel);
+	l2tp_tunnel_put(tunnel);
 
 out:
 	return ret;
···
 	if (ret < 0)
 		goto err_nlmsg_tunnel;
 
-	l2tp_tunnel_dec_refcount(tunnel);
+	l2tp_tunnel_put(tunnel);
 
 	return genlmsg_unicast(net, msg, info->snd_portid);
 
 err_nlmsg_tunnel:
-	l2tp_tunnel_dec_refcount(tunnel);
+	l2tp_tunnel_put(tunnel);
 err_nlmsg:
 	nlmsg_free(msg);
 err:
 	return ret;
 }
 
+struct l2tp_nl_cb_data {
+	unsigned long tkey;
+	unsigned long skey;
+};
+
 static int l2tp_nl_cmd_tunnel_dump(struct sk_buff *skb, struct netlink_callback *cb)
 {
-	int ti = cb->args[0];
+	struct l2tp_nl_cb_data *cbd = (void *)&cb->ctx[0];
+	unsigned long key = cbd->tkey;
 	struct l2tp_tunnel *tunnel;
 	struct net *net = sock_net(skb->sk);
 
 	for (;;) {
-		tunnel = l2tp_tunnel_get_nth(net, ti);
+		tunnel = l2tp_tunnel_get_next(net, &key);
 		if (!tunnel)
 			goto out;
 
 		if (l2tp_nl_tunnel_send(skb, NETLINK_CB(cb->skb).portid,
 					cb->nlh->nlmsg_seq, NLM_F_MULTI,
 					tunnel, L2TP_CMD_TUNNEL_GET) < 0) {
-			l2tp_tunnel_dec_refcount(tunnel);
+			l2tp_tunnel_put(tunnel);
 			goto out;
 		}
-		l2tp_tunnel_dec_refcount(tunnel);
+		l2tp_tunnel_put(tunnel);
 
-		ti++;
+		key++;
 	}
 
 out:
-	cb->args[0] = ti;
+	cbd->tkey = key;
 
 	return skb->len;
 }
···
 		if (session) {
 			ret = l2tp_session_notify(&l2tp_nl_family, info, session,
 						  L2TP_CMD_SESSION_CREATE);
-			l2tp_session_dec_refcount(session);
+			l2tp_session_put(session);
 		}
 	}
 
 out_tunnel:
-	l2tp_tunnel_dec_refcount(tunnel);
+	l2tp_tunnel_put(tunnel);
 out:
 	return ret;
 }
···
 		if (l2tp_nl_cmd_ops[pw_type] && l2tp_nl_cmd_ops[pw_type]->session_delete)
 			l2tp_nl_cmd_ops[pw_type]->session_delete(session);
 
-	l2tp_session_dec_refcount(session);
+	l2tp_session_put(session);
 
 out:
 	return ret;
···
 	ret = l2tp_session_notify(&l2tp_nl_family, info,
 				  session, L2TP_CMD_SESSION_MODIFY);
 
-	l2tp_session_dec_refcount(session);
+	l2tp_session_put(session);
 
 out:
 	return ret;
···
 
 	ret = genlmsg_unicast(genl_info_net(info), msg, info->snd_portid);
 
-	l2tp_session_dec_refcount(session);
+	l2tp_session_put(session);
 
 	return ret;
 
 err_ref_msg:
 	nlmsg_free(msg);
 err_ref:
-	l2tp_session_dec_refcount(session);
+	l2tp_session_put(session);
 err:
 	return ret;
 }
 
 static int l2tp_nl_cmd_session_dump(struct sk_buff *skb, struct netlink_callback *cb)
 {
+	struct l2tp_nl_cb_data *cbd = (void *)&cb->ctx[0];
 	struct net *net = sock_net(skb->sk);
 	struct l2tp_session *session;
 	struct l2tp_tunnel *tunnel = NULL;
-	int ti = cb->args[0];
-	int si = cb->args[1];
+	unsigned long tkey = cbd->tkey;
+	unsigned long skey = cbd->skey;
 
 	for (;;) {
 		if (!tunnel) {
-			tunnel = l2tp_tunnel_get_nth(net, ti);
+			tunnel = l2tp_tunnel_get_next(net, &tkey);
 			if (!tunnel)
 				goto out;
 		}
 
-		session = l2tp_session_get_nth(tunnel, si);
+		session = l2tp_session_get_next(net, tunnel->sock, tunnel->version,
+						tunnel->tunnel_id, &skey);
 		if (!session) {
-			ti++;
-			l2tp_tunnel_dec_refcount(tunnel);
+			tkey++;
+			l2tp_tunnel_put(tunnel);
 			tunnel = NULL;
-			si = 0;
+			skey = 0;
 			continue;
 		}
 
 		if (l2tp_nl_session_send(skb, NETLINK_CB(cb->skb).portid,
 					 cb->nlh->nlmsg_seq, NLM_F_MULTI,
 					 session, L2TP_CMD_SESSION_GET) < 0) {
-			l2tp_session_dec_refcount(session);
-			l2tp_tunnel_dec_refcount(tunnel);
+			l2tp_session_put(session);
+			l2tp_tunnel_put(tunnel);
 			break;
 		}
-		l2tp_session_dec_refcount(session);
+		l2tp_session_put(session);
 
-		si++;
+		skey++;
 	}
 
 out:
-	cb->args[0] = ti;
-	cb->args[1] = si;
+	cbd->tkey = tkey;
+	cbd->skey = skey;
 
 	return skb->len;
 }

net/l2tp/l2tp_ppp.c

···
 
 /* Helpers to obtain tunnel/session contexts from sockets.
  */
-static inline struct l2tp_session *pppol2tp_sock_to_session(struct sock *sk)
+static struct l2tp_session *pppol2tp_sock_to_session(struct sock *sk)
 {
 	struct l2tp_session *session;
 
···
 	l2tp_xmit_skb(session, skb);
 	local_bh_enable();
 
-	l2tp_session_dec_refcount(session);
+	l2tp_session_put(session);
 
 	return total_len;
 
 error_put_sess:
-	l2tp_session_dec_refcount(session);
+	l2tp_session_put(session);
 error:
 	return error;
 }
···
 	l2tp_xmit_skb(session, skb);
 	local_bh_enable();
 
-	l2tp_session_dec_refcount(session);
+	l2tp_session_put(session);
 
 	return 1;
 
 abort_put_sess:
-	l2tp_session_dec_refcount(session);
+	l2tp_session_put(session);
 abort:
 	/* Free the original skb */
 	kfree_skb(skb);
···
 		sock_put(ps->__sk);
 
 		/* drop ref taken when we referenced socket via sk_user_data */
-		l2tp_session_dec_refcount(session);
+		l2tp_session_put(session);
 	}
 }
 
···
 	if (session) {
 		l2tp_session_delete(session);
 		/* drop ref taken by pppol2tp_sock_to_session */
-		l2tp_session_dec_refcount(session);
+		l2tp_session_put(session);
 	}
 
 	release_sock(sk);
···
 			if (error < 0)
 				return ERR_PTR(error);
 
-			l2tp_tunnel_inc_refcount(tunnel);
+			refcount_inc(&tunnel->ref_count);
 			error = l2tp_tunnel_register(tunnel, net, &tcfg);
 			if (error < 0) {
 				kfree(tunnel);
···
 
 		/* Error if socket is not prepped */
 		if (!tunnel->sock) {
-			l2tp_tunnel_dec_refcount(tunnel);
+			l2tp_tunnel_put(tunnel);
 			return ERR_PTR(-ENOENT);
 		}
 	}
···
 
 		pppol2tp_session_init(session);
 		ps = l2tp_session_priv(session);
-		l2tp_session_inc_refcount(session);
+		refcount_inc(&session->ref_count);
 
 		mutex_lock(&ps->sk_lock);
 		error = l2tp_session_register(session, tunnel);
 		if (error < 0) {
 			mutex_unlock(&ps->sk_lock);
-			l2tp_session_dec_refcount(session);
+			l2tp_session_put(session);
 			goto end;
 		}
 
···
 			l2tp_tunnel_delete(tunnel);
 	}
 	if (drop_refcnt)
-		l2tp_session_dec_refcount(session);
-	l2tp_tunnel_dec_refcount(tunnel);
+		l2tp_session_put(session);
+	l2tp_tunnel_put(tunnel);
 	release_sock(sk);
 
 	return error;
···
 	return 0;
 
 err_sess:
-	l2tp_session_dec_refcount(session);
+	l2tp_session_put(session);
 err:
 	return error;
 }
···
 
 	error = len;
 
-	l2tp_session_dec_refcount(session);
+	l2tp_session_put(session);
 end:
 	return error;
 }
···
 		return -EBADR;
 
 	if (session->pwtype != L2TP_PWTYPE_PPP) {
-		l2tp_session_dec_refcount(session);
+		l2tp_session_put(session);
 		return -EBADR;
 	}
 
 	pppol2tp_copy_stats(stats, &session->stats);
-	l2tp_session_dec_refcount(session);
+	l2tp_session_put(session);
 
 	return 0;
 }
···
 		err = pppol2tp_session_setsockopt(sk, session, optname, val);
 	}
 
-	l2tp_session_dec_refcount(session);
+	l2tp_session_put(session);
 end:
 	return err;
 }
···
 	err = 0;
 
 end_put_sess:
-	l2tp_session_dec_refcount(session);
+	l2tp_session_put(session);
 end:
 	return err;
 }
···
 
 struct pppol2tp_seq_data {
 	struct seq_net_private p;
-	int tunnel_idx;			/* current tunnel */
-	int session_idx;		/* index of session within current tunnel */
+	unsigned long tkey;		/* lookup key of current tunnel */
+	unsigned long skey;		/* lookup key of current session */
 	struct l2tp_tunnel *tunnel;
 	struct l2tp_session *session;	/* NULL means get next tunnel */
 };
···
 {
 	/* Drop reference taken during previous invocation */
 	if (pd->tunnel)
-		l2tp_tunnel_dec_refcount(pd->tunnel);
+		l2tp_tunnel_put(pd->tunnel);
 
 	for (;;) {
-		pd->tunnel = l2tp_tunnel_get_nth(net, pd->tunnel_idx);
-		pd->tunnel_idx++;
+		pd->tunnel = l2tp_tunnel_get_next(net, &pd->tkey);
+		pd->tkey++;
 
 		/* Only accept L2TPv2 tunnels */
 		if (!pd->tunnel || pd->tunnel->version == 2)
 			return;
 
-		l2tp_tunnel_dec_refcount(pd->tunnel);
+		l2tp_tunnel_put(pd->tunnel);
 	}
 }
 
···
 {
 	/* Drop reference taken during previous invocation */
 	if (pd->session)
-		l2tp_session_dec_refcount(pd->session);
+		l2tp_session_put(pd->session);
 
-	pd->session = l2tp_session_get_nth(pd->tunnel, pd->session_idx);
-	pd->session_idx++;
+	pd->session = l2tp_session_get_next(net, pd->tunnel->sock,
+					    pd->tunnel->version,
+					    pd->tunnel->tunnel_id, &pd->skey);
+	pd->skey++;
 
 	if (!pd->session) {
-		pd->session_idx = 0;
+		pd->skey = 0;
 		pppol2tp_next_tunnel(net, pd);
 	}
 }
···
 	 * or pppol2tp_next_tunnel().
 	 */
 	if (pd->session) {
-		l2tp_session_dec_refcount(pd->session);
+		l2tp_session_put(pd->session);
 		pd->session = NULL;
 	}
 	if (pd->tunnel) {
-		l2tp_tunnel_dec_refcount(pd->tunnel);
+		l2tp_tunnel_put(pd->tunnel);
 		pd->tunnel = NULL;
 	}
 }