Merge branch 'l2tp'

Tom Parkin says:

====================
This l2tp bugfix patchset addresses a number of issues.

The first five patches in the series prevent l2tp sessions pinning an l2tp
tunnel open.  This occurs because the l2tp tunnel is torn down in the tunnel
socket destructor, but each session holds a tunnel socket reference which
prevents tunnels with sessions being deleted.  The solution I've implemented
here involves adding a .destroy hook to udp code, as discussed previously on
netdev[1].

The subsequent seven patches address futher bugs exposed by fixing the problem
above, or exposed through stress testing the implementation above.  Patch 11
(avoid deadlock in l2tp stats update) isn't directly related to tunnel/session
lifetimes, but it does prevent deadlocks on i386 kernels running on 64 bit
hardware.

This patchset has been tested on 32 and 64 bit preempt/non-preempt kernels,
using iproute2, openl2tp, and custom-made stress test code.

[1] http://comments.gmane.org/gmane.linux.network/259169
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

10 files changed, 220 insertions, 248 deletions

diff --git a/include/linux/udp.h b/include/linux/udp.h
index 9d81de123c90..42278bbf7a88 100644
--- a/include/linux/udp.h
+++ b/include/linux/udp.h
@@ -68,6 +68,7 @@ struct udp_sock {
 	 * For encapsulation sockets.
 	 */
 	int (*encap_rcv)(struct sock *sk, struct sk_buff *skb);
+	void (*encap_destroy)(struct sock *sk);
 };
 
 static inline struct udp_sock *udp_sk(const struct sock *sk)
diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index 265c42cf963c..0a073a263720 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -1762,9 +1762,16 @@ int udp_rcv(struct sk_buff *skb)
 
 void udp_destroy_sock(struct sock *sk)
 {
+	struct udp_sock *up = udp_sk(sk);
 	bool slow = lock_sock_fast(sk);
 	udp_flush_pending_frames(sk);
 	unlock_sock_fast(sk, slow);
+	if (static_key_false(&udp_encap_needed) && up->encap_type) {
+		void (*encap_destroy)(struct sock *sk);
+		encap_destroy = ACCESS_ONCE(up->encap_destroy);
+		if (encap_destroy)
+			encap_destroy(sk);
+	}
 }
 
 /*
diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
index 599e1ba6d1ce..d8e5e852fc7a 100644
--- a/net/ipv6/udp.c
+++ b/net/ipv6/udp.c
@@ -1285,10 +1285,18 @@ do_confirm:
 
 void udpv6_destroy_sock(struct sock *sk)
 {
+	struct udp_sock *up = udp_sk(sk);
 	lock_sock(sk);
 	udp_v6_flush_pending_frames(sk);
 	release_sock(sk);
 
+	if (static_key_false(&udpv6_encap_needed) && up->encap_type) {
+		void (*encap_destroy)(struct sock *sk);
+		encap_destroy = ACCESS_ONCE(up->encap_destroy);
+		if (encap_destroy)
+			encap_destroy(sk);
+	}
+
 	inet6_destroy_sock(sk);
 }
 
diff --git a/net/l2tp/l2tp_core.c b/net/l2tp/l2tp_core.c
index d36875f3427e..8aecf5df6656 100644
--- a/net/l2tp/l2tp_core.c
+++ b/net/l2tp/l2tp_core.c
@@ -114,7 +114,6 @@ struct l2tp_net {
 
 static void l2tp_session_set_header_len(struct l2tp_session *session, int version);
 static void l2tp_tunnel_free(struct l2tp_tunnel *tunnel);
-static void l2tp_tunnel_closeall(struct l2tp_tunnel *tunnel);
 
 static inline struct l2tp_net *l2tp_pernet(struct net *net)
 {
@@ -192,6 +191,7 @@ struct sock *l2tp_tunnel_sock_lookup(struct l2tp_tunnel *tunnel)
 	} else {
 		/* Socket is owned by kernelspace */
 		sk = tunnel->sock;
+		sock_hold(sk);
 	}
 
 out:
@@ -210,6 +210,7 @@ void l2tp_tunnel_sock_put(struct sock *sk)
 		}
 		sock_put(sk);
 	}
+	sock_put(sk);
 }
 EXPORT_SYMBOL_GPL(l2tp_tunnel_sock_put);
 
@@ -373,10 +374,8 @@ static void l2tp_recv_queue_skb(struct l2tp_session *session, struct sk_buff *sk
 	struct sk_buff *skbp;
 	struct sk_buff *tmp;
 	u32 ns = L2TP_SKB_CB(skb)->ns;
-	struct l2tp_stats *sstats;
 
 	spin_lock_bh(&session->reorder_q.lock);
-	sstats = &session->stats;
 	skb_queue_walk_safe(&session->reorder_q, skbp, tmp) {
 		if (L2TP_SKB_CB(skbp)->ns > ns) {
 			__skb_queue_before(&session->reorder_q, skbp, skb);
@@ -384,9 +383,7 @@ static void l2tp_recv_queue_skb(struct l2tp_session *session, struct sk_buff *sk
 				 "%s: pkt %hu, inserted before %hu, reorder_q len=%d\n",
 				 session->name, ns, L2TP_SKB_CB(skbp)->ns,
 				 skb_queue_len(&session->reorder_q));
-			u64_stats_update_begin(&sstats->syncp);
-			sstats->rx_oos_packets++;
-			u64_stats_update_end(&sstats->syncp);
+			atomic_long_inc(&session->stats.rx_oos_packets);
 			goto out;
 		}
 	}
@@ -403,23 +400,16 @@ static void l2tp_recv_dequeue_skb(struct l2tp_session *session, struct sk_buff *
 {
 	struct l2tp_tunnel *tunnel = session->tunnel;
 	int length = L2TP_SKB_CB(skb)->length;
-	struct l2tp_stats *tstats, *sstats;
 
 	/* We're about to requeue the skb, so return resources
 	 * to its current owner (a socket receive buffer).
 	 */
 	skb_orphan(skb);
 
-	tstats = &tunnel->stats;
-	u64_stats_update_begin(&tstats->syncp);
-	sstats = &session->stats;
-	u64_stats_update_begin(&sstats->syncp);
-	tstats->rx_packets++;
-	tstats->rx_bytes += length;
-	sstats->rx_packets++;
-	sstats->rx_bytes += length;
-	u64_stats_update_end(&tstats->syncp);
-	u64_stats_update_end(&sstats->syncp);
+	atomic_long_inc(&tunnel->stats.rx_packets);
+	atomic_long_add(length, &tunnel->stats.rx_bytes);
+	atomic_long_inc(&session->stats.rx_packets);
+	atomic_long_add(length, &session->stats.rx_bytes);
 
 	if (L2TP_SKB_CB(skb)->has_seq) {
 		/* Bump our Nr */
@@ -450,7 +440,6 @@ static void l2tp_recv_dequeue(struct l2tp_session *session)
 {
 	struct sk_buff *skb;
 	struct sk_buff *tmp;
-	struct l2tp_stats *sstats;
 
 	/* If the pkt at the head of the queue has the nr that we
 	 * expect to send up next, dequeue it and any other
@@ -458,13 +447,10 @@ static void l2tp_recv_dequeue(struct l2tp_session *session)
 	 */
 start:
 	spin_lock_bh(&session->reorder_q.lock);
-	sstats = &session->stats;
 	skb_queue_walk_safe(&session->reorder_q, skb, tmp) {
 		if (time_after(jiffies, L2TP_SKB_CB(skb)->expires)) {
-			u64_stats_update_begin(&sstats->syncp);
-			sstats->rx_seq_discards++;
-			sstats->rx_errors++;
-			u64_stats_update_end(&sstats->syncp);
+			atomic_long_inc(&session->stats.rx_seq_discards);
+			atomic_long_inc(&session->stats.rx_errors);
 			l2tp_dbg(session, L2TP_MSG_SEQ,
 				 "%s: oos pkt %u len %d discarded (too old), waiting for %u, reorder_q_len=%d\n",
 				 session->name, L2TP_SKB_CB(skb)->ns,
@@ -623,7 +609,6 @@ void l2tp_recv_common(struct l2tp_session *session, struct sk_buff *skb,
 	struct l2tp_tunnel *tunnel = session->tunnel;
 	int offset;
 	u32 ns, nr;
-	struct l2tp_stats *sstats = &session->stats;
 
 	/* The ref count is increased since we now hold a pointer to
 	 * the session. Take care to decrement the refcnt when exiting
@@ -640,9 +625,7 @@ void l2tp_recv_common(struct l2tp_session *session, struct sk_buff *skb,
 				  "%s: cookie mismatch (%u/%u). Discarding.\n",
 				  tunnel->name, tunnel->tunnel_id,
 				  session->session_id);
-			u64_stats_update_begin(&sstats->syncp);
-			sstats->rx_cookie_discards++;
-			u64_stats_update_end(&sstats->syncp);
+			atomic_long_inc(&session->stats.rx_cookie_discards);
 			goto discard;
 		}
 		ptr += session->peer_cookie_len;
@@ -711,9 +694,7 @@ void l2tp_recv_common(struct l2tp_session *session, struct sk_buff *skb,
 			l2tp_warn(session, L2TP_MSG_SEQ,
 				  "%s: recv data has no seq numbers when required. Discarding.\n",
 				  session->name);
-			u64_stats_update_begin(&sstats->syncp);
-			sstats->rx_seq_discards++;
-			u64_stats_update_end(&sstats->syncp);
+			atomic_long_inc(&session->stats.rx_seq_discards);
 			goto discard;
 		}
 
@@ -732,9 +713,7 @@ void l2tp_recv_common(struct l2tp_session *session, struct sk_buff *skb,
 			l2tp_warn(session, L2TP_MSG_SEQ,
 				  "%s: recv data has no seq numbers when required. Discarding.\n",
 				  session->name);
-			u64_stats_update_begin(&sstats->syncp);
-			sstats->rx_seq_discards++;
-			u64_stats_update_end(&sstats->syncp);
+			atomic_long_inc(&session->stats.rx_seq_discards);
 			goto discard;
 		}
 	}
@@ -788,9 +767,7 @@ void l2tp_recv_common(struct l2tp_session *session, struct sk_buff *skb,
 			 * packets
 			 */
 			if (L2TP_SKB_CB(skb)->ns != session->nr) {
-				u64_stats_update_begin(&sstats->syncp);
-				sstats->rx_seq_discards++;
-				u64_stats_update_end(&sstats->syncp);
+				atomic_long_inc(&session->stats.rx_seq_discards);
 				l2tp_dbg(session, L2TP_MSG_SEQ,
 					 "%s: oos pkt %u len %d discarded, waiting for %u, reorder_q_len=%d\n",
 					 session->name, L2TP_SKB_CB(skb)->ns,
@@ -816,9 +793,7 @@ void l2tp_recv_common(struct l2tp_session *session, struct sk_buff *skb,
 	return;
 
 discard:
-	u64_stats_update_begin(&sstats->syncp);
-	sstats->rx_errors++;
-	u64_stats_update_end(&sstats->syncp);
+	atomic_long_inc(&session->stats.rx_errors);
 	kfree_skb(skb);
 
 	if (session->deref)
@@ -828,6 +803,23 @@ discard:
 }
 EXPORT_SYMBOL(l2tp_recv_common);
 
+/* Drop skbs from the session's reorder_q
+ */
+int l2tp_session_queue_purge(struct l2tp_session *session)
+{
+	struct sk_buff *skb = NULL;
+	BUG_ON(!session);
+	BUG_ON(session->magic != L2TP_SESSION_MAGIC);
+	while ((skb = skb_dequeue(&session->reorder_q))) {
+		atomic_long_inc(&session->stats.rx_errors);
+		kfree_skb(skb);
+		if (session->deref)
+			(*session->deref)(session);
+	}
+	return 0;
+}
+EXPORT_SYMBOL_GPL(l2tp_session_queue_purge);
+
 /* Internal UDP receive frame. Do the real work of receiving an L2TP data frame
  * here. The skb is not on a list when we get here.
  * Returns 0 if the packet was a data packet and was successfully passed on.
@@ -843,7 +835,6 @@ static int l2tp_udp_recv_core(struct l2tp_tunnel *tunnel, struct sk_buff *skb,
 	u32 tunnel_id, session_id;
 	u16 version;
 	int length;
-	struct l2tp_stats *tstats;
 
 	if (tunnel->sock && l2tp_verify_udp_checksum(tunnel->sock, skb))
 		goto discard_bad_csum;
@@ -932,10 +923,7 @@ static int l2tp_udp_recv_core(struct l2tp_tunnel *tunnel, struct sk_buff *skb,
 discard_bad_csum:
 	LIMIT_NETDEBUG("%s: UDP: bad checksum\n", tunnel->name);
 	UDP_INC_STATS_USER(tunnel->l2tp_net, UDP_MIB_INERRORS, 0);
-	tstats = &tunnel->stats;
-	u64_stats_update_begin(&tstats->syncp);
-	tstats->rx_errors++;
-	u64_stats_update_end(&tstats->syncp);
+	atomic_long_inc(&tunnel->stats.rx_errors);
 	kfree_skb(skb);
 
 	return 0;
@@ -1062,7 +1050,6 @@ static int l2tp_xmit_core(struct l2tp_session *session, struct sk_buff *skb,
 	struct l2tp_tunnel *tunnel = session->tunnel;
 	unsigned int len = skb->len;
 	int error;
-	struct l2tp_stats *tstats, *sstats;
 
 	/* Debug */
 	if (session->send_seq)
@@ -1091,21 +1078,15 @@ static int l2tp_xmit_core(struct l2tp_session *session, struct sk_buff *skb,
 		error = ip_queue_xmit(skb, fl);
 
 	/* Update stats */
-	tstats = &tunnel->stats;
-	u64_stats_update_begin(&tstats->syncp);
-	sstats = &session->stats;
-	u64_stats_update_begin(&sstats->syncp);
 	if (error >= 0) {
-		tstats->tx_packets++;
-		tstats->tx_bytes += len;
-		sstats->tx_packets++;
-		sstats->tx_bytes += len;
+		atomic_long_inc(&tunnel->stats.tx_packets);
+		atomic_long_add(len, &tunnel->stats.tx_bytes);
+		atomic_long_inc(&session->stats.tx_packets);
+		atomic_long_add(len, &session->stats.tx_bytes);
 	} else {
-		tstats->tx_errors++;
-		sstats->tx_errors++;
+		atomic_long_inc(&tunnel->stats.tx_errors);
+		atomic_long_inc(&session->stats.tx_errors);
 	}
-	u64_stats_update_end(&tstats->syncp);
-	u64_stats_update_end(&sstats->syncp);
 
 	return 0;
 }
@@ -1282,6 +1263,7 @@ static void l2tp_tunnel_destruct(struct sock *sk)
 		/* No longer an encapsulation socket. See net/ipv4/udp.c */
 		(udp_sk(sk))->encap_type = 0;
 		(udp_sk(sk))->encap_rcv = NULL;
+		(udp_sk(sk))->encap_destroy = NULL;
 		break;
 	case L2TP_ENCAPTYPE_IP:
 		break;
@@ -1311,7 +1293,7 @@ end:
 
 /* When the tunnel is closed, all the attached sessions need to go too.
  */
-static void l2tp_tunnel_closeall(struct l2tp_tunnel *tunnel)
+void l2tp_tunnel_closeall(struct l2tp_tunnel *tunnel)
 {
 	int hash;
 	struct hlist_node *walk;
@@ -1334,25 +1316,13 @@ again:
 
 			hlist_del_init(&session->hlist);
 
-			/* Since we should hold the sock lock while
-			 * doing any unbinding, we need to release the
-			 * lock we're holding before taking that lock.
-			 * Hold a reference to the sock so it doesn't
-			 * disappear as we're jumping between locks.
-			 */
 			if (session->ref != NULL)
 				(*session->ref)(session);
 
 			write_unlock_bh(&tunnel->hlist_lock);
 
-			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();
-			}
+			__l2tp_session_unhash(session);
+			l2tp_session_queue_purge(session);
 
 			if (session->session_close != NULL)
 				(*session->session_close)(session);
@@ -1360,6 +1330,8 @@ again:
 			if (session->deref != NULL)
 				(*session->deref)(session);
 
+			l2tp_session_dec_refcount(session);
+
 			write_lock_bh(&tunnel->hlist_lock);
 
 			/* Now restart from the beginning of this hash
@@ -1372,6 +1344,17 @@ again:
 	}
 	write_unlock_bh(&tunnel->hlist_lock);
 }
+EXPORT_SYMBOL_GPL(l2tp_tunnel_closeall);
+
+/* Tunnel socket destroy hook for UDP encapsulation */
+static void l2tp_udp_encap_destroy(struct sock *sk)
+{
+	struct l2tp_tunnel *tunnel = l2tp_sock_to_tunnel(sk);
+	if (tunnel) {
+		l2tp_tunnel_closeall(tunnel);
+		sock_put(sk);
+	}
+}
 
 /* Really kill the tunnel.
  * Come here only when all sessions have been cleared from the tunnel.
@@ -1397,19 +1380,21 @@ static void l2tp_tunnel_del_work(struct work_struct *work)
 		return;
 
 	sock = sk->sk_socket;
-	BUG_ON(!sock);
 
-	/* If the tunnel socket was created directly by the kernel, use the
-	 * sk_* API to release the socket now.  Otherwise go through the
-	 * inet_* layer to shut the socket down, and let userspace close it.
+	/* If the tunnel socket was created by userspace, then go through the
+	 * inet layer to shut the socket down, and let userspace close it.
+	 * Otherwise, if we created the socket directly within the kernel, use
+	 * the sk API to release it here.
 	 * In either case the tunnel resources are freed in the socket
 	 * destructor when the tunnel socket goes away.
 	 */
-	if (sock->file == NULL) {
-		kernel_sock_shutdown(sock, SHUT_RDWR);
-		sk_release_kernel(sk);
+	if (tunnel->fd >= 0) {
+		if (sock)
+			inet_shutdown(sock, 2);
 	} else {
-		inet_shutdown(sock, 2);
+		if (sock)
+			kernel_sock_shutdown(sock, SHUT_RDWR);
+		sk_release_kernel(sk);
 	}
 
 	l2tp_tunnel_sock_put(sk);
@@ -1668,6 +1653,7 @@ int l2tp_tunnel_create(struct net *net, int fd, int version, u32 tunnel_id, u32
 		/* Mark socket as an encapsulation socket. See net/ipv4/udp.c */
 		udp_sk(sk)->encap_type = UDP_ENCAP_L2TPINUDP;
 		udp_sk(sk)->encap_rcv = l2tp_udp_encap_recv;
+		udp_sk(sk)->encap_destroy = l2tp_udp_encap_destroy;
 #if IS_ENABLED(CONFIG_IPV6)
 		if (sk->sk_family == PF_INET6)
 			udpv6_encap_enable();
@@ -1723,6 +1709,7 @@ EXPORT_SYMBOL_GPL(l2tp_tunnel_create);
  */
 int l2tp_tunnel_delete(struct l2tp_tunnel *tunnel)
 {
+	l2tp_tunnel_closeall(tunnel);
 	return (false == queue_work(l2tp_wq, &tunnel->del_work));
 }
 EXPORT_SYMBOL_GPL(l2tp_tunnel_delete);
@@ -1731,62 +1718,71 @@ EXPORT_SYMBOL_GPL(l2tp_tunnel_delete);
  */
 void l2tp_session_free(struct l2tp_session *session)
 {
-	struct l2tp_tunnel *tunnel;
+	struct l2tp_tunnel *tunnel = session->tunnel;
 
 	BUG_ON(atomic_read(&session->ref_count) != 0);
 
-	tunnel = session->tunnel;
-	if (tunnel != NULL) {
+	if (tunnel) {
 		BUG_ON(tunnel->magic != L2TP_TUNNEL_MAGIC);
+		if (session->session_id != 0)
+			atomic_dec(&l2tp_session_count);
+		sock_put(tunnel->sock);
+		session->tunnel = NULL;
+		l2tp_tunnel_dec_refcount(tunnel);
+	}
+
+	kfree(session);
 
-		/* Delete the session from the hash */
+	return;
+}
+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);
 
-		/* Unlink from the global hash if not L2TPv2 */
+		/* 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();
 		}
-
-		if (session->session_id != 0)
-			atomic_dec(&l2tp_session_count);
-
-		sock_put(tunnel->sock);
-
-		/* This will delete the tunnel context if this
-		 * is the last session on the tunnel.
-		 */
-		session->tunnel = NULL;
-		l2tp_tunnel_dec_refcount(tunnel);
 	}
-
-	kfree(session);
-
-	return;
 }
-EXPORT_SYMBOL_GPL(l2tp_session_free);
+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)
 {
+	if (session->ref)
+		(*session->ref)(session);
+	__l2tp_session_unhash(session);
+	l2tp_session_queue_purge(session);
 	if (session->session_close != NULL)
 		(*session->session_close)(session);
-
+	if (session->deref)
+		(*session->ref)(session);
 	l2tp_session_dec_refcount(session);
-
 	return 0;
 }
 EXPORT_SYMBOL_GPL(l2tp_session_delete);
 
-
 /* We come here whenever a session's send_seq, cookie_len or
  * l2specific_len parameters are set.
  */
diff --git a/net/l2tp/l2tp_core.h b/net/l2tp/l2tp_core.h
index 8eb8f1d47f3a..485a490fd990 100644
--- a/net/l2tp/l2tp_core.h
+++ b/net/l2tp/l2tp_core.h
@@ -36,16 +36,15 @@ enum {
 struct sk_buff;
 
 struct l2tp_stats {
-	u64			tx_packets;
-	u64			tx_bytes;
-	u64			tx_errors;
-	u64			rx_packets;
-	u64			rx_bytes;
-	u64			rx_seq_discards;
-	u64			rx_oos_packets;
-	u64			rx_errors;
-	u64			rx_cookie_discards;
-	struct u64_stats_sync	syncp;
+	atomic_long_t		tx_packets;
+	atomic_long_t		tx_bytes;
+	atomic_long_t		tx_errors;
+	atomic_long_t		rx_packets;
+	atomic_long_t		rx_bytes;
+	atomic_long_t		rx_seq_discards;
+	atomic_long_t		rx_oos_packets;
+	atomic_long_t		rx_errors;
+	atomic_long_t		rx_cookie_discards;
 };
 
 struct l2tp_tunnel;
@@ -240,11 +239,14 @@ extern struct l2tp_tunnel *l2tp_tunnel_find(struct net *net, u32 tunnel_id);
 extern struct l2tp_tunnel *l2tp_tunnel_find_nth(struct net *net, int nth);
 
 extern 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);
+extern void l2tp_tunnel_closeall(struct l2tp_tunnel *tunnel);
 extern int l2tp_tunnel_delete(struct l2tp_tunnel *tunnel);
 extern 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);
+extern void __l2tp_session_unhash(struct l2tp_session *session);
 extern int l2tp_session_delete(struct l2tp_session *session);
 extern void l2tp_session_free(struct l2tp_session *session);
 extern void l2tp_recv_common(struct l2tp_session *session, struct sk_buff *skb, unsigned char *ptr, unsigned char *optr, u16 hdrflags, int length, int (*payload_hook)(struct sk_buff *skb));
+extern int l2tp_session_queue_purge(struct l2tp_session *session);
 extern int l2tp_udp_encap_recv(struct sock *sk, struct sk_buff *skb);
 
 extern int l2tp_xmit_skb(struct l2tp_session *session, struct sk_buff *skb, int hdr_len);
diff --git a/net/l2tp/l2tp_debugfs.c b/net/l2tp/l2tp_debugfs.c
index c3813bc84552..072d7202e182 100644
--- a/net/l2tp/l2tp_debugfs.c
+++ b/net/l2tp/l2tp_debugfs.c
@@ -146,14 +146,14 @@ static void l2tp_dfs_seq_tunnel_show(struct seq_file *m, void *v)
 		   tunnel->sock ? atomic_read(&tunnel->sock->sk_refcnt) : 0,
 		   atomic_read(&tunnel->ref_count));
 
-	seq_printf(m, " %08x rx %llu/%llu/%llu rx %llu/%llu/%llu\n",
+	seq_printf(m, " %08x rx %ld/%ld/%ld rx %ld/%ld/%ld\n",
 		   tunnel->debug,
-		   (unsigned long long)tunnel->stats.tx_packets,
-		   (unsigned long long)tunnel->stats.tx_bytes,
-		   (unsigned long long)tunnel->stats.tx_errors,
-		   (unsigned long long)tunnel->stats.rx_packets,
-		   (unsigned long long)tunnel->stats.rx_bytes,
-		   (unsigned long long)tunnel->stats.rx_errors);
+		   atomic_long_read(&tunnel->stats.tx_packets),
+		   atomic_long_read(&tunnel->stats.tx_bytes),
+		   atomic_long_read(&tunnel->stats.tx_errors),
+		   atomic_long_read(&tunnel->stats.rx_packets),
+		   atomic_long_read(&tunnel->stats.rx_bytes),
+		   atomic_long_read(&tunnel->stats.rx_errors));
 
 	if (tunnel->show != NULL)
 		tunnel->show(m, tunnel);
@@ -203,14 +203,14 @@ static void l2tp_dfs_seq_session_show(struct seq_file *m, void *v)
 		seq_printf(m, "\n");
 	}
 
-	seq_printf(m, "   %hu/%hu tx %llu/%llu/%llu rx %llu/%llu/%llu\n",
+	seq_printf(m, "   %hu/%hu tx %ld/%ld/%ld rx %ld/%ld/%ld\n",
 		   session->nr, session->ns,
-		   (unsigned long long)session->stats.tx_packets,
-		   (unsigned long long)session->stats.tx_bytes,
-		   (unsigned long long)session->stats.tx_errors,
-		   (unsigned long long)session->stats.rx_packets,
-		   (unsigned long long)session->stats.rx_bytes,
-		   (unsigned long long)session->stats.rx_errors);
+		   atomic_long_read(&session->stats.tx_packets),
+		   atomic_long_read(&session->stats.tx_bytes),
+		   atomic_long_read(&session->stats.tx_errors),
+		   atomic_long_read(&session->stats.rx_packets),
+		   atomic_long_read(&session->stats.rx_bytes),
+		   atomic_long_read(&session->stats.rx_errors));
 
 	if (session->show != NULL)
 		session->show(m, session);
diff --git a/net/l2tp/l2tp_ip.c b/net/l2tp/l2tp_ip.c
index 7f41b7051269..571db8dd2292 100644
--- a/net/l2tp/l2tp_ip.c
+++ b/net/l2tp/l2tp_ip.c
@@ -228,10 +228,16 @@ static void l2tp_ip_close(struct sock *sk, long timeout)
 static void l2tp_ip_destroy_sock(struct sock *sk)
 {
 	struct sk_buff *skb;
+	struct l2tp_tunnel *tunnel = l2tp_sock_to_tunnel(sk);
 
 	while ((skb = __skb_dequeue_tail(&sk->sk_write_queue)) != NULL)
 		kfree_skb(skb);
 
+	if (tunnel) {
+		l2tp_tunnel_closeall(tunnel);
+		sock_put(sk);
+	}
+
 	sk_refcnt_debug_dec(sk);
 }
 
diff --git a/net/l2tp/l2tp_ip6.c b/net/l2tp/l2tp_ip6.c
index 41f2f8126ebc..c74f5a91ff6a 100644
--- a/net/l2tp/l2tp_ip6.c
+++ b/net/l2tp/l2tp_ip6.c
@@ -241,10 +241,17 @@ static void l2tp_ip6_close(struct sock *sk, long timeout)
 
 static void l2tp_ip6_destroy_sock(struct sock *sk)
 {
+	struct l2tp_tunnel *tunnel = l2tp_sock_to_tunnel(sk);
+
 	lock_sock(sk);
 	ip6_flush_pending_frames(sk);
 	release_sock(sk);
 
+	if (tunnel) {
+		l2tp_tunnel_closeall(tunnel);
+		sock_put(sk);
+	}
+
 	inet6_destroy_sock(sk);
 }
 
diff --git a/net/l2tp/l2tp_netlink.c b/net/l2tp/l2tp_netlink.c
index c1bab22db85e..0825ff26e113 100644
--- a/net/l2tp/l2tp_netlink.c
+++ b/net/l2tp/l2tp_netlink.c
@@ -246,8 +246,6 @@ static int l2tp_nl_tunnel_send(struct sk_buff *skb, u32 portid, u32 seq, int fla
 #if IS_ENABLED(CONFIG_IPV6)
 	struct ipv6_pinfo *np = NULL;
 #endif
-	struct l2tp_stats stats;
-	unsigned int start;
 
 	hdr = genlmsg_put(skb, portid, seq, &l2tp_nl_family, flags,
 			  L2TP_CMD_TUNNEL_GET);
@@ -265,28 +263,22 @@ static int l2tp_nl_tunnel_send(struct sk_buff *skb, u32 portid, u32 seq, int fla
 	if (nest == NULL)
 		goto nla_put_failure;
 
-	do {
-		start = u64_stats_fetch_begin(&tunnel->stats.syncp);
-		stats.tx_packets = tunnel->stats.tx_packets;
-		stats.tx_bytes = tunnel->stats.tx_bytes;
-		stats.tx_errors = tunnel->stats.tx_errors;
-		stats.rx_packets = tunnel->stats.rx_packets;
-		stats.rx_bytes = tunnel->stats.rx_bytes;
-		stats.rx_errors = tunnel->stats.rx_errors;
-		stats.rx_seq_discards = tunnel->stats.rx_seq_discards;
-		stats.rx_oos_packets = tunnel->stats.rx_oos_packets;
-	} while (u64_stats_fetch_retry(&tunnel->stats.syncp, start));
-
-	if (nla_put_u64(skb, L2TP_ATTR_TX_PACKETS, stats.tx_packets) ||
-	    nla_put_u64(skb, L2TP_ATTR_TX_BYTES, stats.tx_bytes) ||
-	    nla_put_u64(skb, L2TP_ATTR_TX_ERRORS, stats.tx_errors) ||
-	    nla_put_u64(skb, L2TP_ATTR_RX_PACKETS, stats.rx_packets) ||
-	    nla_put_u64(skb, L2TP_ATTR_RX_BYTES, stats.rx_bytes) ||
+	if (nla_put_u64(skb, L2TP_ATTR_TX_PACKETS,
+		    atomic_long_read(&tunnel->stats.tx_packets)) ||
+	    nla_put_u64(skb, L2TP_ATTR_TX_BYTES,
+		    atomic_long_read(&tunnel->stats.tx_bytes)) ||
+	    nla_put_u64(skb, L2TP_ATTR_TX_ERRORS,
+		    atomic_long_read(&tunnel->stats.tx_errors)) ||
+	    nla_put_u64(skb, L2TP_ATTR_RX_PACKETS,
+		    atomic_long_read(&tunnel->stats.rx_packets)) ||
+	    nla_put_u64(skb, L2TP_ATTR_RX_BYTES,
+		    atomic_long_read(&tunnel->stats.rx_bytes)) ||
 	    nla_put_u64(skb, L2TP_ATTR_RX_SEQ_DISCARDS,
-			stats.rx_seq_discards) ||
+		    atomic_long_read(&tunnel->stats.rx_seq_discards)) ||
 	    nla_put_u64(skb, L2TP_ATTR_RX_OOS_PACKETS,
-			stats.rx_oos_packets) ||
-	    nla_put_u64(skb, L2TP_ATTR_RX_ERRORS, stats.rx_errors))
+		    atomic_long_read(&tunnel->stats.rx_oos_packets)) ||
+	    nla_put_u64(skb, L2TP_ATTR_RX_ERRORS,
+		    atomic_long_read(&tunnel->stats.rx_errors)))
 		goto nla_put_failure;
 	nla_nest_end(skb, nest);
 
@@ -612,8 +604,6 @@ static int l2tp_nl_session_send(struct sk_buff *skb, u32 portid, u32 seq, int fl
 	struct nlattr *nest;
 	struct l2tp_tunnel *tunnel = session->tunnel;
 	struct sock *sk = NULL;
-	struct l2tp_stats stats;
-	unsigned int start;
 
 	sk = tunnel->sock;
 
@@ -656,28 +646,22 @@ static int l2tp_nl_session_send(struct sk_buff *skb, u32 portid, u32 seq, int fl
 	if (nest == NULL)
 		goto nla_put_failure;
 
-	do {
-		start = u64_stats_fetch_begin(&session->stats.syncp);
-		stats.tx_packets = session->stats.tx_packets;
-		stats.tx_bytes = session->stats.tx_bytes;
-		stats.tx_errors = session->stats.tx_errors;
-		stats.rx_packets = session->stats.rx_packets;
-		stats.rx_bytes = session->stats.rx_bytes;
-		stats.rx_errors = session->stats.rx_errors;
-		stats.rx_seq_discards = session->stats.rx_seq_discards;
-		stats.rx_oos_packets = session->stats.rx_oos_packets;
-	} while (u64_stats_fetch_retry(&session->stats.syncp, start));
-
-	if (nla_put_u64(skb, L2TP_ATTR_TX_PACKETS, stats.tx_packets) ||
-	    nla_put_u64(skb, L2TP_ATTR_TX_BYTES, stats.tx_bytes) ||
-	    nla_put_u64(skb, L2TP_ATTR_TX_ERRORS, stats.tx_errors) ||
-	    nla_put_u64(skb, L2TP_ATTR_RX_PACKETS, stats.rx_packets) ||
-	    nla_put_u64(skb, L2TP_ATTR_RX_BYTES, stats.rx_bytes) ||
+	if (nla_put_u64(skb, L2TP_ATTR_TX_PACKETS,
+		atomic_long_read(&session->stats.tx_packets)) ||
+	    nla_put_u64(skb, L2TP_ATTR_TX_BYTES,
+		atomic_long_read(&session->stats.tx_bytes)) ||
+	    nla_put_u64(skb, L2TP_ATTR_TX_ERRORS,
+		atomic_long_read(&session->stats.tx_errors)) ||
+	    nla_put_u64(skb, L2TP_ATTR_RX_PACKETS,
+		atomic_long_read(&session->stats.rx_packets)) ||
+	    nla_put_u64(skb, L2TP_ATTR_RX_BYTES,
+		atomic_long_read(&session->stats.rx_bytes)) ||
 	    nla_put_u64(skb, L2TP_ATTR_RX_SEQ_DISCARDS,
-			stats.rx_seq_discards) ||
+		atomic_long_read(&session->stats.rx_seq_discards)) ||
 	    nla_put_u64(skb, L2TP_ATTR_RX_OOS_PACKETS,
-			stats.rx_oos_packets) ||
-	    nla_put_u64(skb, L2TP_ATTR_RX_ERRORS, stats.rx_errors))
+		atomic_long_read(&session->stats.rx_oos_packets)) ||
+	    nla_put_u64(skb, L2TP_ATTR_RX_ERRORS,
+		atomic_long_read(&session->stats.rx_errors)))
 		goto nla_put_failure;
 	nla_nest_end(skb, nest);
 
diff --git a/net/l2tp/l2tp_ppp.c b/net/l2tp/l2tp_ppp.c
index 6a53371dba1f..637a341c1e2d 100644
--- a/net/l2tp/l2tp_ppp.c
+++ b/net/l2tp/l2tp_ppp.c
@@ -97,6 +97,7 @@
 #include <net/ip.h>
 #include <net/udp.h>
 #include <net/xfrm.h>
+#include <net/inet_common.h>
 
 #include <asm/byteorder.h>
 #include <linux/atomic.h>
@@ -259,7 +260,7 @@ static void pppol2tp_recv(struct l2tp_session *session, struct sk_buff *skb, int
 			  session->name);
 
 		/* Not bound. Nothing we can do, so discard. */
-		session->stats.rx_errors++;
+		atomic_long_inc(&session->stats.rx_errors);
 		kfree_skb(skb);
 	}
 
@@ -447,34 +448,16 @@ static void pppol2tp_session_close(struct l2tp_session *session)
 {
 	struct pppol2tp_session *ps = l2tp_session_priv(session);
 	struct sock *sk = ps->sock;
-	struct sk_buff *skb;
+	struct socket *sock = sk->sk_socket;
 
 	BUG_ON(session->magic != L2TP_SESSION_MAGIC);
 
-	if (session->session_id == 0)
-		goto out;
-
-	if (sk != NULL) {
-		lock_sock(sk);
-
-		if (sk->sk_state & (PPPOX_CONNECTED | PPPOX_BOUND)) {
-			pppox_unbind_sock(sk);
-			sk->sk_state = PPPOX_DEAD;
-			sk->sk_state_change(sk);
-		}
-
-		/* Purge any queued data */
-		skb_queue_purge(&sk->sk_receive_queue);
-		skb_queue_purge(&sk->sk_write_queue);
-		while ((skb = skb_dequeue(&session->reorder_q))) {
-			kfree_skb(skb);
-			sock_put(sk);
-		}
 
-		release_sock(sk);
+	if (sock) {
+		inet_shutdown(sock, 2);
+		/* Don't let the session go away before our socket does */
+		l2tp_session_inc_refcount(session);
 	}
-
-out:
 	return;
 }
 
@@ -483,19 +466,12 @@ out:
  */
 static void pppol2tp_session_destruct(struct sock *sk)
 {
-	struct l2tp_session *session;
-
-	if (sk->sk_user_data != NULL) {
-		session = sk->sk_user_data;
-		if (session == NULL)
-			goto out;
-
+	struct l2tp_session *session = sk->sk_user_data;
+	if (session) {
 		sk->sk_user_data = NULL;
 		BUG_ON(session->magic != L2TP_SESSION_MAGIC);
 		l2tp_session_dec_refcount(session);
 	}
-
-out:
 	return;
 }
 
@@ -525,16 +501,13 @@ static int pppol2tp_release(struct socket *sock)
 	session = pppol2tp_sock_to_session(sk);
 
 	/* Purge any queued data */
-	skb_queue_purge(&sk->sk_receive_queue);
-	skb_queue_purge(&sk->sk_write_queue);
 	if (session != NULL) {
-		struct sk_buff *skb;
-		while ((skb = skb_dequeue(&session->reorder_q))) {
-			kfree_skb(skb);
-			sock_put(sk);
-		}
+		__l2tp_session_unhash(session);
+		l2tp_session_queue_purge(session);
 		sock_put(sk);
 	}
+	skb_queue_purge(&sk->sk_receive_queue);
+	skb_queue_purge(&sk->sk_write_queue);
 
 	release_sock(sk);
 
@@ -880,18 +853,6 @@ out:
 	return error;
 }
 
-/* Called when deleting sessions via the netlink interface.
- */
-static int pppol2tp_session_delete(struct l2tp_session *session)
-{
-	struct pppol2tp_session *ps = l2tp_session_priv(session);
-
-	if (ps->sock == NULL)
-		l2tp_session_dec_refcount(session);
-
-	return 0;
-}
-
 #endif /* CONFIG_L2TP_V3 */
 
 /* getname() support.
@@ -1025,14 +986,14 @@ end:
 static void pppol2tp_copy_stats(struct pppol2tp_ioc_stats *dest,
 				struct l2tp_stats *stats)
 {
-	dest->tx_packets = stats->tx_packets;
-	dest->tx_bytes = stats->tx_bytes;
-	dest->tx_errors = stats->tx_errors;
-	dest->rx_packets = stats->rx_packets;
-	dest->rx_bytes = stats->rx_bytes;
-	dest->rx_seq_discards = stats->rx_seq_discards;
-	dest->rx_oos_packets = stats->rx_oos_packets;
-	dest->rx_errors = stats->rx_errors;
+	dest->tx_packets = atomic_long_read(&stats->tx_packets);
+	dest->tx_bytes = atomic_long_read(&stats->tx_bytes);
+	dest->tx_errors = atomic_long_read(&stats->tx_errors);
+	dest->rx_packets = atomic_long_read(&stats->rx_packets);
+	dest->rx_bytes = atomic_long_read(&stats->rx_bytes);
+	dest->rx_seq_discards = atomic_long_read(&stats->rx_seq_discards);
+	dest->rx_oos_packets = atomic_long_read(&stats->rx_oos_packets);
+	dest->rx_errors = atomic_long_read(&stats->rx_errors);
 }
 
 /* Session ioctl helper.
@@ -1666,14 +1627,14 @@ static void pppol2tp_seq_tunnel_show(struct seq_file *m, void *v)
 		   tunnel->name,
 		   (tunnel == tunnel->sock->sk_user_data) ? 'Y' : 'N',
 		   atomic_read(&tunnel->ref_count) - 1);
-	seq_printf(m, " %08x %llu/%llu/%llu %llu/%llu/%llu\n",
+	seq_printf(m, " %08x %ld/%ld/%ld %ld/%ld/%ld\n",
 		   tunnel->debug,
-		   (unsigned long long)tunnel->stats.tx_packets,
-		   (unsigned long long)tunnel->stats.tx_bytes,
-		   (unsigned long long)tunnel->stats.tx_errors,
-		   (unsigned long long)tunnel->stats.rx_packets,
-		   (unsigned long long)tunnel->stats.rx_bytes,
-		   (unsigned long long)tunnel->stats.rx_errors);
+		   atomic_long_read(&tunnel->stats.tx_packets),
+		   atomic_long_read(&tunnel->stats.tx_bytes),
+		   atomic_long_read(&tunnel->stats.tx_errors),
+		   atomic_long_read(&tunnel->stats.rx_packets),
+		   atomic_long_read(&tunnel->stats.rx_bytes),
+		   atomic_long_read(&tunnel->stats.rx_errors));
 }
 
 static void pppol2tp_seq_session_show(struct seq_file *m, void *v)
@@ -1708,14 +1669,14 @@ static void pppol2tp_seq_session_show(struct seq_file *m, void *v)
 		   session->lns_mode ? "LNS" : "LAC",
 		   session->debug,
 		   jiffies_to_msecs(session->reorder_timeout));
-	seq_printf(m, "   %hu/%hu %llu/%llu/%llu %llu/%llu/%llu\n",
+	seq_printf(m, "   %hu/%hu %ld/%ld/%ld %ld/%ld/%ld\n",
 		   session->nr, session->ns,
-		   (unsigned long long)session->stats.tx_packets,
-		   (unsigned long long)session->stats.tx_bytes,
-		   (unsigned long long)session->stats.tx_errors,
-		   (unsigned long long)session->stats.rx_packets,
-		   (unsigned long long)session->stats.rx_bytes,
-		   (unsigned long long)session->stats.rx_errors);
+		   atomic_long_read(&session->stats.tx_packets),
+		   atomic_long_read(&session->stats.tx_bytes),
+		   atomic_long_read(&session->stats.tx_errors),
+		   atomic_long_read(&session->stats.rx_packets),
+		   atomic_long_read(&session->stats.rx_bytes),
+		   atomic_long_read(&session->stats.rx_errors));
 
 	if (po)
 		seq_printf(m, "   interface %s\n", ppp_dev_name(&po->chan));
@@ -1839,7 +1800,7 @@ static const struct pppox_proto pppol2tp_proto = {
 
 static const struct l2tp_nl_cmd_ops pppol2tp_nl_cmd_ops = {
 	.session_create	= pppol2tp_session_create,
-	.session_delete	= pppol2tp_session_delete,
+	.session_delete	= l2tp_session_delete,
 };
 
 #endif /* CONFIG_L2TP_V3 */