From 12923365eb3db5710adcd6abb69e93899e003554 Mon Sep 17 00:00:00 2001
From: Tom Parkin <tparkin@katalix.com>
Date: Sat, 22 Aug 2020 15:59:01 +0100
Subject: [PATCH 1/9] l2tp: don't log data frames

l2tp had logging to trace data frame receipt and transmission, including
code to dump packet contents.  This was originally intended to aid
debugging of core l2tp packet handling, but is of limited use now that
code is stable.

Signed-off-by: Tom Parkin <tparkin@katalix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
---
 net/l2tp/l2tp_core.c | 58 +++++---------------------------------------
 net/l2tp/l2tp_eth.c  | 11 ---------
 net/l2tp/l2tp_ip.c   | 15 ------------
 net/l2tp/l2tp_ip6.c  | 15 ------------
 net/l2tp/l2tp_ppp.c  |  8 ------
 5 files changed, 6 insertions(+), 101 deletions(-)

diff --git a/net/l2tp/l2tp_core.c b/net/l2tp/l2tp_core.c
index 701fc72ad9f42..077f7952912d1 100644
--- a/net/l2tp/l2tp_core.c
+++ b/net/l2tp/l2tp_core.c
@@ -660,7 +660,6 @@ 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;
 
 	/* Parse and check optional cookie */
@@ -686,32 +685,21 @@ void l2tp_recv_common(struct l2tp_session *session, struct sk_buff *skb,
 	L2TP_SKB_CB(skb)->has_seq = 0;
 	if (tunnel->version == L2TP_HDR_VER_2) {
 		if (hdrflags & L2TP_HDRFLAG_S) {
-			ns = ntohs(*(__be16 *)ptr);
-			ptr += 2;
-			nr = ntohs(*(__be16 *)ptr);
-			ptr += 2;
-
 			/* Store L2TP info in the skb */
-			L2TP_SKB_CB(skb)->ns = ns;
+			L2TP_SKB_CB(skb)->ns = ntohs(*(__be16 *)ptr);
 			L2TP_SKB_CB(skb)->has_seq = 1;
+			ptr += 2;
+			/* Skip past nr in the header */
+			ptr += 2;
 
-			l2tp_dbg(session, L2TP_MSG_SEQ,
-				 "%s: recv data ns=%u, nr=%u, session nr=%u\n",
-				 session->name, ns, nr, session->nr);
 		}
 	} else if (session->l2specific_type == L2TP_L2SPECTYPE_DEFAULT) {
 		u32 l2h = ntohl(*(__be32 *)ptr);
 
 		if (l2h & 0x40000000) {
-			ns = l2h & 0x00ffffff;
-
 			/* Store L2TP info in the skb */
-			L2TP_SKB_CB(skb)->ns = ns;
+			L2TP_SKB_CB(skb)->ns = l2h & 0x00ffffff;
 			L2TP_SKB_CB(skb)->has_seq = 1;
-
-			l2tp_dbg(session, L2TP_MSG_SEQ,
-				 "%s: recv data ns=%u, session nr=%u\n",
-				 session->name, ns, session->nr);
 		}
 		ptr += 4;
 	}
@@ -853,16 +841,6 @@ static int l2tp_udp_recv_core(struct l2tp_tunnel *tunnel, struct sk_buff *skb)
 		goto error;
 	}
 
-	/* Trace packet contents, if enabled */
-	if (tunnel->debug & L2TP_MSG_DATA) {
-		length = min(32u, skb->len);
-		if (!pskb_may_pull(skb, length))
-			goto error;
-
-		pr_debug("%s: recv\n", tunnel->name);
-		print_hex_dump_bytes("", DUMP_PREFIX_OFFSET, skb->data, length);
-	}
-
 	/* Point to L2TP header */
 	optr = skb->data;
 	ptr = skb->data;
@@ -883,12 +861,8 @@ static int l2tp_udp_recv_core(struct l2tp_tunnel *tunnel, struct sk_buff *skb)
 	length = skb->len;
 
 	/* If type is control packet, it is handled by userspace. */
-	if (hdrflags & L2TP_HDRFLAG_T) {
-		l2tp_dbg(tunnel, L2TP_MSG_DATA,
-			 "%s: recv control packet, len=%d\n",
-			 tunnel->name, length);
+	if (hdrflags & L2TP_HDRFLAG_T)
 		goto error;
-	}
 
 	/* Skip flags */
 	ptr += 2;
@@ -953,9 +927,6 @@ int l2tp_udp_encap_recv(struct sock *sk, struct sk_buff *skb)
 	if (!tunnel)
 		goto pass_up;
 
-	l2tp_dbg(tunnel, L2TP_MSG_DATA, "%s: received %d bytes\n",
-		 tunnel->name, skb->len);
-
 	if (l2tp_udp_recv_core(tunnel, skb))
 		goto pass_up;
 
@@ -1049,23 +1020,6 @@ static void l2tp_xmit_core(struct l2tp_session *session, struct sk_buff *skb,
 	unsigned int len = skb->len;
 	int error;
 
-	/* Debug */
-	if (session->send_seq)
-		l2tp_dbg(session, L2TP_MSG_DATA, "%s: send %zd bytes, ns=%u\n",
-			 session->name, data_len, session->ns - 1);
-	else
-		l2tp_dbg(session, L2TP_MSG_DATA, "%s: send %zd bytes\n",
-			 session->name, data_len);
-
-	if (session->debug & L2TP_MSG_DATA) {
-		int uhlen = (tunnel->encap == L2TP_ENCAPTYPE_UDP) ? sizeof(struct udphdr) : 0;
-		unsigned char *datap = skb->data + uhlen;
-
-		pr_debug("%s: xmit\n", session->name);
-		print_hex_dump_bytes("", DUMP_PREFIX_OFFSET,
-				     datap, min_t(size_t, 32, len - uhlen));
-	}
-
 	/* Queue the packet to IP for output */
 	skb->ignore_df = 1;
 	skb_dst_drop(skb);
diff --git a/net/l2tp/l2tp_eth.c b/net/l2tp/l2tp_eth.c
index 7ed2b4eced940..657edad1263e4 100644
--- a/net/l2tp/l2tp_eth.c
+++ b/net/l2tp/l2tp_eth.c
@@ -128,17 +128,6 @@ static void l2tp_eth_dev_recv(struct l2tp_session *session, struct sk_buff *skb,
 	struct net_device *dev;
 	struct l2tp_eth *priv;
 
-	if (session->debug & L2TP_MSG_DATA) {
-		unsigned int length;
-
-		length = min(32u, skb->len);
-		if (!pskb_may_pull(skb, length))
-			goto error;
-
-		pr_debug("%s: eth recv\n", session->name);
-		print_hex_dump_bytes("", DUMP_PREFIX_OFFSET, skb->data, length);
-	}
-
 	if (!pskb_may_pull(skb, ETH_HLEN))
 		goto error;
 
diff --git a/net/l2tp/l2tp_ip.c b/net/l2tp/l2tp_ip.c
index df2a35b5714a8..7086d97f293c6 100644
--- a/net/l2tp/l2tp_ip.c
+++ b/net/l2tp/l2tp_ip.c
@@ -118,7 +118,6 @@ static int l2tp_ip_recv(struct sk_buff *skb)
 	struct l2tp_session *session;
 	struct l2tp_tunnel *tunnel = NULL;
 	struct iphdr *iph;
-	int length;
 
 	if (!pskb_may_pull(skb, 4))
 		goto discard;
@@ -147,20 +146,6 @@ static int l2tp_ip_recv(struct sk_buff *skb)
 	if (!tunnel)
 		goto discard_sess;
 
-	/* Trace packet contents, if enabled */
-	if (tunnel->debug & L2TP_MSG_DATA) {
-		length = min(32u, skb->len);
-		if (!pskb_may_pull(skb, length))
-			goto discard_sess;
-
-		/* Point to L2TP header */
-		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);
-	}
-
 	if (l2tp_v3_ensure_opt_in_linear(session, skb, &ptr, &optr))
 		goto discard_sess;
 
diff --git a/net/l2tp/l2tp_ip6.c b/net/l2tp/l2tp_ip6.c
index bc757bc7e2648..409ea8927f6cf 100644
--- a/net/l2tp/l2tp_ip6.c
+++ b/net/l2tp/l2tp_ip6.c
@@ -131,7 +131,6 @@ static int l2tp_ip6_recv(struct sk_buff *skb)
 	struct l2tp_session *session;
 	struct l2tp_tunnel *tunnel = NULL;
 	struct ipv6hdr *iph;
-	int length;
 
 	if (!pskb_may_pull(skb, 4))
 		goto discard;
@@ -160,20 +159,6 @@ static int l2tp_ip6_recv(struct sk_buff *skb)
 	if (!tunnel)
 		goto discard_sess;
 
-	/* Trace packet contents, if enabled */
-	if (tunnel->debug & L2TP_MSG_DATA) {
-		length = min(32u, skb->len);
-		if (!pskb_may_pull(skb, length))
-			goto discard_sess;
-
-		/* Point to L2TP header */
-		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);
-	}
-
 	if (l2tp_v3_ensure_opt_in_linear(session, skb, &ptr, &optr))
 		goto discard_sess;
 
diff --git a/net/l2tp/l2tp_ppp.c b/net/l2tp/l2tp_ppp.c
index 13c3153b40d64..ee1663a3ca7ba 100644
--- a/net/l2tp/l2tp_ppp.c
+++ b/net/l2tp/l2tp_ppp.c
@@ -237,17 +237,9 @@ static void pppol2tp_recv(struct l2tp_session *session, struct sk_buff *skb, int
 	if (sk->sk_state & PPPOX_BOUND) {
 		struct pppox_sock *po;
 
-		l2tp_dbg(session, L2TP_MSG_DATA,
-			 "%s: recv %d byte data frame, passing to ppp\n",
-			 session->name, data_len);
-
 		po = pppox_sk(sk);
 		ppp_input(&po->chan, skb);
 	} else {
-		l2tp_dbg(session, L2TP_MSG_DATA,
-			 "%s: recv %d byte data frame, passing to L2TP socket\n",
-			 session->name, data_len);
-
 		if (sock_queue_rcv_skb(sk, skb) < 0) {
 			atomic_long_inc(&session->stats.rx_errors);
 			kfree_skb(skb);

From ab141e3733d16ba24740de515694697835f24636 Mon Sep 17 00:00:00 2001
From: Tom Parkin <tparkin@katalix.com>
Date: Sat, 22 Aug 2020 15:59:02 +0100
Subject: [PATCH 2/9] l2tp: remove noisy logging, use appropriate log levels

l2tp_ppp in particular had a lot of log messages for tracing
[get|set]sockopt calls.  These aren't especially useful, so remove
these messages.

Several log messages flagging error conditions were logged using
l2tp_info: they're better off as l2tp_warn.

Signed-off-by: Tom Parkin <tparkin@katalix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
---
 net/l2tp/l2tp_core.c | 16 ++++------------
 net/l2tp/l2tp_ppp.c  | 32 +-------------------------------
 2 files changed, 5 insertions(+), 43 deletions(-)

diff --git a/net/l2tp/l2tp_core.c b/net/l2tp/l2tp_core.c
index 077f7952912d1..a3017c46f6531 100644
--- a/net/l2tp/l2tp_core.c
+++ b/net/l2tp/l2tp_core.c
@@ -665,7 +665,7 @@ void l2tp_recv_common(struct l2tp_session *session, struct sk_buff *skb,
 	/* Parse and check optional cookie */
 	if (session->peer_cookie_len > 0) {
 		if (memcmp(ptr, &session->peer_cookie[0], session->peer_cookie_len)) {
-			l2tp_info(tunnel, L2TP_MSG_DATA,
+			l2tp_warn(tunnel, L2TP_MSG_DATA,
 				  "%s: cookie mismatch (%u/%u). Discarding.\n",
 				  tunnel->name, tunnel->tunnel_id,
 				  session->session_id);
@@ -835,7 +835,7 @@ static int l2tp_udp_recv_core(struct l2tp_tunnel *tunnel, struct sk_buff *skb)
 
 	/* Short packet? */
 	if (!pskb_may_pull(skb, L2TP_HDR_SIZE_MAX)) {
-		l2tp_info(tunnel, L2TP_MSG_DATA,
+		l2tp_warn(tunnel, L2TP_MSG_DATA,
 			  "%s: recv short packet (len=%d)\n",
 			  tunnel->name, skb->len);
 		goto error;
@@ -851,7 +851,7 @@ static int l2tp_udp_recv_core(struct l2tp_tunnel *tunnel, struct sk_buff *skb)
 	/* Check protocol version */
 	version = hdrflags & L2TP_HDR_VER_MASK;
 	if (version != tunnel->version) {
-		l2tp_info(tunnel, L2TP_MSG_DATA,
+		l2tp_warn(tunnel, L2TP_MSG_DATA,
 			  "%s: recv protocol version mismatch: got %d expected %d\n",
 			  tunnel->name, version, tunnel->version);
 		goto error;
@@ -891,7 +891,7 @@ static int l2tp_udp_recv_core(struct l2tp_tunnel *tunnel, struct sk_buff *skb)
 			l2tp_session_dec_refcount(session);
 
 		/* Not found? Pass to userspace to deal with */
-		l2tp_info(tunnel, L2TP_MSG_DATA,
+		l2tp_warn(tunnel, L2TP_MSG_DATA,
 			  "%s: no session found (%u/%u). Passing up.\n",
 			  tunnel->name, tunnel_id, session_id);
 		goto error;
@@ -1149,8 +1149,6 @@ static void l2tp_tunnel_destruct(struct sock *sk)
 	if (!tunnel)
 		goto end;
 
-	l2tp_info(tunnel, L2TP_MSG_CONTROL, "%s: closing...\n", tunnel->name);
-
 	/* Disable udp encapsulation */
 	switch (tunnel->encap) {
 	case L2TP_ENCAPTYPE_UDP:
@@ -1209,9 +1207,6 @@ static void l2tp_tunnel_closeall(struct l2tp_tunnel *tunnel)
 	struct hlist_node *tmp;
 	struct l2tp_session *session;
 
-	l2tp_info(tunnel, L2TP_MSG_CONTROL, "%s: closing all sessions...\n",
-		  tunnel->name);
-
 	write_lock_bh(&tunnel->hlist_lock);
 	tunnel->acpt_newsess = false;
 	for (hash = 0; hash < L2TP_HASH_SIZE; hash++) {
@@ -1219,9 +1214,6 @@ static void l2tp_tunnel_closeall(struct l2tp_tunnel *tunnel)
 		hlist_for_each_safe(walk, tmp, &tunnel->session_hlist[hash]) {
 			session = hlist_entry(walk, struct l2tp_session, hlist);
 
-			l2tp_info(session, L2TP_MSG_CONTROL,
-				  "%s: closing session\n", session->name);
-
 			hlist_del_init(&session->hlist);
 
 			if (test_and_set_bit(0, &session->dead))
diff --git a/net/l2tp/l2tp_ppp.c b/net/l2tp/l2tp_ppp.c
index ee1663a3ca7ba..660ea95e09108 100644
--- a/net/l2tp/l2tp_ppp.c
+++ b/net/l2tp/l2tp_ppp.c
@@ -251,7 +251,7 @@ static void pppol2tp_recv(struct l2tp_session *session, struct sk_buff *skb, int
 
 no_sock:
 	rcu_read_unlock();
-	l2tp_info(session, L2TP_MSG_DATA, "%s: no socket\n", session->name);
+	l2tp_warn(session, L2TP_MSG_DATA, "%s: no socket\n", session->name);
 	kfree_skb(skb);
 }
 
@@ -832,8 +832,6 @@ static int pppol2tp_connect(struct socket *sock, struct sockaddr *uservaddr,
 	drop_refcnt = false;
 
 	sk->sk_state = PPPOX_CONNECTED;
-	l2tp_info(session, L2TP_MSG_CONTROL, "%s: created\n",
-		  session->name);
 
 end:
 	if (error) {
@@ -1150,8 +1148,6 @@ static int pppol2tp_tunnel_setsockopt(struct sock *sk,
 	switch (optname) {
 	case PPPOL2TP_SO_DEBUG:
 		tunnel->debug = val;
-		l2tp_info(tunnel, L2TP_MSG_CONTROL, "%s: set debug=%x\n",
-			  tunnel->name, tunnel->debug);
 		break;
 
 	default:
@@ -1177,9 +1173,6 @@ static int pppol2tp_session_setsockopt(struct sock *sk,
 			break;
 		}
 		session->recv_seq = !!val;
-		l2tp_info(session, L2TP_MSG_CONTROL,
-			  "%s: set recv_seq=%d\n",
-			  session->name, session->recv_seq);
 		break;
 
 	case PPPOL2TP_SO_SENDSEQ:
@@ -1195,9 +1188,6 @@ static int pppol2tp_session_setsockopt(struct sock *sk,
 				PPPOL2TP_L2TP_HDR_SIZE_NOSEQ;
 		}
 		l2tp_session_set_header_len(session, session->tunnel->version);
-		l2tp_info(session, L2TP_MSG_CONTROL,
-			  "%s: set send_seq=%d\n",
-			  session->name, session->send_seq);
 		break;
 
 	case PPPOL2TP_SO_LNSMODE:
@@ -1206,22 +1196,14 @@ static int pppol2tp_session_setsockopt(struct sock *sk,
 			break;
 		}
 		session->lns_mode = !!val;
-		l2tp_info(session, L2TP_MSG_CONTROL,
-			  "%s: set lns_mode=%d\n",
-			  session->name, session->lns_mode);
 		break;
 
 	case PPPOL2TP_SO_DEBUG:
 		session->debug = val;
-		l2tp_info(session, L2TP_MSG_CONTROL, "%s: set debug=%x\n",
-			  session->name, session->debug);
 		break;
 
 	case PPPOL2TP_SO_REORDERTO:
 		session->reorder_timeout = msecs_to_jiffies(val);
-		l2tp_info(session, L2TP_MSG_CONTROL,
-			  "%s: set reorder_timeout=%d\n",
-			  session->name, session->reorder_timeout);
 		break;
 
 	default:
@@ -1290,8 +1272,6 @@ static int pppol2tp_tunnel_getsockopt(struct sock *sk,
 	switch (optname) {
 	case PPPOL2TP_SO_DEBUG:
 		*val = tunnel->debug;
-		l2tp_info(tunnel, L2TP_MSG_CONTROL, "%s: get debug=%x\n",
-			  tunnel->name, tunnel->debug);
 		break;
 
 	default:
@@ -1313,32 +1293,22 @@ static int pppol2tp_session_getsockopt(struct sock *sk,
 	switch (optname) {
 	case PPPOL2TP_SO_RECVSEQ:
 		*val = session->recv_seq;
-		l2tp_info(session, L2TP_MSG_CONTROL,
-			  "%s: get recv_seq=%d\n", session->name, *val);
 		break;
 
 	case PPPOL2TP_SO_SENDSEQ:
 		*val = session->send_seq;
-		l2tp_info(session, L2TP_MSG_CONTROL,
-			  "%s: get send_seq=%d\n", session->name, *val);
 		break;
 
 	case PPPOL2TP_SO_LNSMODE:
 		*val = session->lns_mode;
-		l2tp_info(session, L2TP_MSG_CONTROL,
-			  "%s: get lns_mode=%d\n", session->name, *val);
 		break;
 
 	case PPPOL2TP_SO_DEBUG:
 		*val = session->debug;
-		l2tp_info(session, L2TP_MSG_CONTROL, "%s: get debug=%d\n",
-			  session->name, *val);
 		break;
 
 	case PPPOL2TP_SO_REORDERTO:
 		*val = (int)jiffies_to_msecs(session->reorder_timeout);
-		l2tp_info(session, L2TP_MSG_CONTROL,
-			  "%s: get reorder_timeout=%d\n", session->name, *val);
 		break;
 
 	default:

From 5ee759cda51b9b1c28994ea36e314427a58cb6d7 Mon Sep 17 00:00:00 2001
From: Tom Parkin <tparkin@katalix.com>
Date: Sat, 22 Aug 2020 15:59:03 +0100
Subject: [PATCH 3/9] l2tp: use standard API for warning log messages

The l2tp_* log wrappers only emit messages of a given category if the
tunnel or session structure has the appropriate flag set in its debug
field.  Flags default to being unset.

For warning messages, this doesn't make a lot of sense since an
administrator is likely to want to know about datapath warnings without
needing to tweak the debug flags setting for a given tunnel or session
instance.

Modify l2tp_warn callsites to use pr_warn_ratelimited instead for
unconditional output of warning messages.

Signed-off-by: Tom Parkin <tparkin@katalix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
---
 net/l2tp/l2tp_core.c | 32 +++++++++++++-------------------
 net/l2tp/l2tp_ppp.c  |  2 +-
 2 files changed, 14 insertions(+), 20 deletions(-)

diff --git a/net/l2tp/l2tp_core.c b/net/l2tp/l2tp_core.c
index a3017c46f6531..54f46ed97b3d4 100644
--- a/net/l2tp/l2tp_core.c
+++ b/net/l2tp/l2tp_core.c
@@ -665,10 +665,9 @@ void l2tp_recv_common(struct l2tp_session *session, struct sk_buff *skb,
 	/* Parse and check optional cookie */
 	if (session->peer_cookie_len > 0) {
 		if (memcmp(ptr, &session->peer_cookie[0], session->peer_cookie_len)) {
-			l2tp_warn(tunnel, L2TP_MSG_DATA,
-				  "%s: cookie mismatch (%u/%u). Discarding.\n",
-				  tunnel->name, tunnel->tunnel_id,
-				  session->session_id);
+			pr_warn_ratelimited("%s: cookie mismatch (%u/%u). Discarding.\n",
+					    tunnel->name, tunnel->tunnel_id,
+					    session->session_id);
 			atomic_long_inc(&session->stats.rx_cookie_discards);
 			goto discard;
 		}
@@ -721,9 +720,8 @@ void l2tp_recv_common(struct l2tp_session *session, struct sk_buff *skb,
 		 * If user has configured mandatory sequence numbers, discard.
 		 */
 		if (session->recv_seq) {
-			l2tp_warn(session, L2TP_MSG_SEQ,
-				  "%s: recv data has no seq numbers when required. Discarding.\n",
-				  session->name);
+			pr_warn_ratelimited("%s: recv data has no seq numbers when required. Discarding.\n",
+					    session->name);
 			atomic_long_inc(&session->stats.rx_seq_discards);
 			goto discard;
 		}
@@ -740,9 +738,8 @@ void l2tp_recv_common(struct l2tp_session *session, struct sk_buff *skb,
 			session->send_seq = 0;
 			l2tp_session_set_header_len(session, tunnel->version);
 		} else if (session->send_seq) {
-			l2tp_warn(session, L2TP_MSG_SEQ,
-				  "%s: recv data has no seq numbers when required. Discarding.\n",
-				  session->name);
+			pr_warn_ratelimited("%s: recv data has no seq numbers when required. Discarding.\n",
+					    session->name);
 			atomic_long_inc(&session->stats.rx_seq_discards);
 			goto discard;
 		}
@@ -835,9 +832,8 @@ static int l2tp_udp_recv_core(struct l2tp_tunnel *tunnel, struct sk_buff *skb)
 
 	/* Short packet? */
 	if (!pskb_may_pull(skb, L2TP_HDR_SIZE_MAX)) {
-		l2tp_warn(tunnel, L2TP_MSG_DATA,
-			  "%s: recv short packet (len=%d)\n",
-			  tunnel->name, skb->len);
+		pr_warn_ratelimited("%s: recv short packet (len=%d)\n",
+				    tunnel->name, skb->len);
 		goto error;
 	}
 
@@ -851,9 +847,8 @@ static int l2tp_udp_recv_core(struct l2tp_tunnel *tunnel, struct sk_buff *skb)
 	/* Check protocol version */
 	version = hdrflags & L2TP_HDR_VER_MASK;
 	if (version != tunnel->version) {
-		l2tp_warn(tunnel, L2TP_MSG_DATA,
-			  "%s: recv protocol version mismatch: got %d expected %d\n",
-			  tunnel->name, version, tunnel->version);
+		pr_warn_ratelimited("%s: recv protocol version mismatch: got %d expected %d\n",
+				    tunnel->name, version, tunnel->version);
 		goto error;
 	}
 
@@ -891,9 +886,8 @@ static int l2tp_udp_recv_core(struct l2tp_tunnel *tunnel, struct sk_buff *skb)
 			l2tp_session_dec_refcount(session);
 
 		/* Not found? Pass to userspace to deal with */
-		l2tp_warn(tunnel, L2TP_MSG_DATA,
-			  "%s: no session found (%u/%u). Passing up.\n",
-			  tunnel->name, tunnel_id, session_id);
+		pr_warn_ratelimited("%s: no session found (%u/%u). Passing up.\n",
+				    tunnel->name, tunnel_id, session_id);
 		goto error;
 	}
 
diff --git a/net/l2tp/l2tp_ppp.c b/net/l2tp/l2tp_ppp.c
index 660ea95e09108..bd6bb17dfadbb 100644
--- a/net/l2tp/l2tp_ppp.c
+++ b/net/l2tp/l2tp_ppp.c
@@ -251,7 +251,7 @@ static void pppol2tp_recv(struct l2tp_session *session, struct sk_buff *skb, int
 
 no_sock:
 	rcu_read_unlock();
-	l2tp_warn(session, L2TP_MSG_DATA, "%s: no socket\n", session->name);
+	pr_warn_ratelimited("%s: no socket in recv\n", session->name);
 	kfree_skb(skb);
 }
 

From 3f117d6f4bbca722d9519e545294852d8e714fae Mon Sep 17 00:00:00 2001
From: Tom Parkin <tparkin@katalix.com>
Date: Sat, 22 Aug 2020 15:59:04 +0100
Subject: [PATCH 4/9] l2tp: add tracepoint infrastructure to core

The l2tp subsystem doesn't currently make use of tracepoints.

As a starting point for adding tracepoints, add skeleton infrastructure
for defining tracepoints for the subsystem, and for having them build
appropriately whether compiled into the kernel or built as a module.

Signed-off-by: Tom Parkin <tparkin@katalix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
---
 net/l2tp/Makefile    |  2 ++
 net/l2tp/l2tp_core.c |  3 +++
 net/l2tp/trace.h     | 15 +++++++++++++++
 3 files changed, 20 insertions(+)
 create mode 100644 net/l2tp/trace.h

diff --git a/net/l2tp/Makefile b/net/l2tp/Makefile
index 399a7e5db2f4a..cf8f27071d3f7 100644
--- a/net/l2tp/Makefile
+++ b/net/l2tp/Makefile
@@ -5,6 +5,8 @@
 
 obj-$(CONFIG_L2TP) += l2tp_core.o
 
+CFLAGS_l2tp_core.o += -I$(src)
+
 # Build l2tp as modules if L2TP is M
 obj-$(subst y,$(CONFIG_L2TP),$(CONFIG_PPPOL2TP)) += l2tp_ppp.o
 obj-$(subst y,$(CONFIG_L2TP),$(CONFIG_L2TP_IP)) += l2tp_ip.o
diff --git a/net/l2tp/l2tp_core.c b/net/l2tp/l2tp_core.c
index 54f46ed97b3d4..aee5b230469f7 100644
--- a/net/l2tp/l2tp_core.c
+++ b/net/l2tp/l2tp_core.c
@@ -62,6 +62,9 @@
 
 #include "l2tp_core.h"
 
+#define CREATE_TRACE_POINTS
+#include "trace.h"
+
 #define L2TP_DRV_VERSION	"V2.0"
 
 /* L2TP header constants */
diff --git a/net/l2tp/trace.h b/net/l2tp/trace.h
new file mode 100644
index 0000000000000..652778291b777
--- /dev/null
+++ b/net/l2tp/trace.h
@@ -0,0 +1,15 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM l2tp
+
+#if !defined(_TRACE_L2TP_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _TRACE_L2TP_H
+
+#endif /* _TRACE_L2TP_H */
+
+/* This part must be outside protection */
+#undef TRACE_INCLUDE_PATH
+#define TRACE_INCLUDE_PATH .
+#undef TRACE_INCLUDE_FILE
+#define TRACE_INCLUDE_FILE trace
+#include <trace/define_trace.h>

From 2a03dd8e115261008d44ffbb69297af56caa585f Mon Sep 17 00:00:00 2001
From: Tom Parkin <tparkin@katalix.com>
Date: Sat, 22 Aug 2020 15:59:05 +0100
Subject: [PATCH 5/9] l2tp: add tracepoint definitions in trace.h

l2tp can provide a better debug experience using tracepoints rather than
printk-style logging.

Add tracepoint definitions in trace.h for use in the l2tp subsystem
code.

Add preprocessor definitions for the length of session and tunnel names
in l2tp_core.h so we can reuse these in trace.h.

Signed-off-by: Tom Parkin <tparkin@katalix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
---
 net/l2tp/l2tp_core.h |   6 +-
 net/l2tp/trace.h     | 196 +++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 200 insertions(+), 2 deletions(-)

diff --git a/net/l2tp/l2tp_core.h b/net/l2tp/l2tp_core.h
index 3468d6b177a00..835c4645a0ecd 100644
--- a/net/l2tp/l2tp_core.h
+++ b/net/l2tp/l2tp_core.h
@@ -66,6 +66,7 @@ struct l2tp_session_cfg {
  * Is linked into a per-tunnel session hashlist; and in the case of an L2TPv3 session into
  * an additional per-net ("global") hashlist.
  */
+#define L2TP_SESSION_NAME_MAX 32
 struct l2tp_session {
 	int			magic;		/* should be L2TP_SESSION_MAGIC */
 	long			dead;
@@ -90,7 +91,7 @@ struct l2tp_session {
 	struct hlist_node	hlist;		/* hash list node */
 	refcount_t		ref_count;
 
-	char			name[32];	/* for logging */
+	char			name[L2TP_SESSION_NAME_MAX]; /* 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? */
@@ -154,6 +155,7 @@ struct l2tp_tunnel_cfg {
  * Maintains a hashlist of sessions belonging to the tunnel instance.
  * Is linked into a per-net list of tunnels.
  */
+#define L2TP_TUNNEL_NAME_MAX 20
 struct l2tp_tunnel {
 	int			magic;		/* Should be L2TP_TUNNEL_MAGIC */
 
@@ -170,7 +172,7 @@ struct l2tp_tunnel {
 	u32			peer_tunnel_id;
 	int			version;	/* 2=>L2TPv2, 3=>L2TPv3 */
 
-	char			name[20];	/* for logging */
+	char			name[L2TP_TUNNEL_NAME_MAX]; /* for logging */
 	int			debug;		/* bitmask of debug message categories */
 	enum l2tp_encap_type	encap;
 	struct l2tp_stats	stats;
diff --git a/net/l2tp/trace.h b/net/l2tp/trace.h
index 652778291b777..8596eaa12a2e6 100644
--- a/net/l2tp/trace.h
+++ b/net/l2tp/trace.h
@@ -5,6 +5,202 @@
 #if !defined(_TRACE_L2TP_H) || defined(TRACE_HEADER_MULTI_READ)
 #define _TRACE_L2TP_H
 
+#include <linux/tracepoint.h>
+#include <linux/l2tp.h>
+#include "l2tp_core.h"
+
+#define encap_type_name(e) { L2TP_ENCAPTYPE_##e, #e }
+#define show_encap_type_name(val) \
+	__print_symbolic(val, \
+			encap_type_name(UDP), \
+			encap_type_name(IP))
+
+#define pw_type_name(p) { L2TP_PWTYPE_##p, #p }
+#define show_pw_type_name(val) \
+	__print_symbolic(val, \
+	pw_type_name(ETH_VLAN), \
+	pw_type_name(ETH), \
+	pw_type_name(PPP), \
+	pw_type_name(PPP_AC), \
+	pw_type_name(IP))
+
+DECLARE_EVENT_CLASS(tunnel_only_evt,
+	TP_PROTO(struct l2tp_tunnel *tunnel),
+	TP_ARGS(tunnel),
+	TP_STRUCT__entry(
+		__array(char, name, L2TP_TUNNEL_NAME_MAX)
+	),
+	TP_fast_assign(
+		memcpy(__entry->name, tunnel->name, L2TP_TUNNEL_NAME_MAX);
+	),
+	TP_printk("%s", __entry->name)
+);
+
+DECLARE_EVENT_CLASS(session_only_evt,
+	TP_PROTO(struct l2tp_session *session),
+	TP_ARGS(session),
+	TP_STRUCT__entry(
+		__array(char, name, L2TP_SESSION_NAME_MAX)
+	),
+	TP_fast_assign(
+		memcpy(__entry->name, session->name, L2TP_SESSION_NAME_MAX);
+	),
+	TP_printk("%s", __entry->name)
+);
+
+TRACE_EVENT(register_tunnel,
+	TP_PROTO(struct l2tp_tunnel *tunnel),
+	TP_ARGS(tunnel),
+	TP_STRUCT__entry(
+		__array(char, name, L2TP_TUNNEL_NAME_MAX)
+		__field(int, fd)
+		__field(u32, tid)
+		__field(u32, ptid)
+		__field(int, version)
+		__field(enum l2tp_encap_type, encap)
+	),
+	TP_fast_assign(
+		memcpy(__entry->name, tunnel->name, L2TP_TUNNEL_NAME_MAX);
+		__entry->fd = tunnel->fd;
+		__entry->tid = tunnel->tunnel_id;
+		__entry->ptid = tunnel->peer_tunnel_id;
+		__entry->version = tunnel->version;
+		__entry->encap = tunnel->encap;
+	),
+	TP_printk("%s: type=%s encap=%s version=L2TPv%d tid=%u ptid=%u fd=%d",
+		__entry->name,
+		__entry->fd > 0 ? "managed" : "unmanaged",
+		show_encap_type_name(__entry->encap),
+		__entry->version,
+		__entry->tid,
+		__entry->ptid,
+		__entry->fd)
+);
+
+DEFINE_EVENT(tunnel_only_evt, delete_tunnel,
+	TP_PROTO(struct l2tp_tunnel *tunnel),
+	TP_ARGS(tunnel)
+);
+
+DEFINE_EVENT(tunnel_only_evt, free_tunnel,
+	TP_PROTO(struct l2tp_tunnel *tunnel),
+	TP_ARGS(tunnel)
+);
+
+TRACE_EVENT(register_session,
+	TP_PROTO(struct l2tp_session *session),
+	TP_ARGS(session),
+	TP_STRUCT__entry(
+		__array(char, name, L2TP_SESSION_NAME_MAX)
+		__field(u32, tid)
+		__field(u32, ptid)
+		__field(u32, sid)
+		__field(u32, psid)
+		__field(enum l2tp_pwtype, pwtype)
+	),
+	TP_fast_assign(
+		memcpy(__entry->name, session->name, L2TP_SESSION_NAME_MAX);
+		__entry->tid = session->tunnel ? session->tunnel->tunnel_id : 0;
+		__entry->ptid = session->tunnel ? session->tunnel->peer_tunnel_id : 0;
+		__entry->sid = session->session_id;
+		__entry->psid = session->peer_session_id;
+		__entry->pwtype = session->pwtype;
+	),
+	TP_printk("%s: pseudowire=%s sid=%u psid=%u tid=%u ptid=%u",
+		__entry->name,
+		show_pw_type_name(__entry->pwtype),
+		__entry->sid,
+		__entry->psid,
+		__entry->sid,
+		__entry->psid)
+);
+
+DEFINE_EVENT(session_only_evt, delete_session,
+	TP_PROTO(struct l2tp_session *session),
+	TP_ARGS(session)
+);
+
+DEFINE_EVENT(session_only_evt, free_session,
+	TP_PROTO(struct l2tp_session *session),
+	TP_ARGS(session)
+);
+
+DEFINE_EVENT(session_only_evt, session_seqnum_lns_enable,
+	TP_PROTO(struct l2tp_session *session),
+	TP_ARGS(session)
+);
+
+DEFINE_EVENT(session_only_evt, session_seqnum_lns_disable,
+	TP_PROTO(struct l2tp_session *session),
+	TP_ARGS(session)
+);
+
+DECLARE_EVENT_CLASS(session_seqnum_evt,
+	TP_PROTO(struct l2tp_session *session),
+	TP_ARGS(session),
+	TP_STRUCT__entry(
+		__array(char, name, L2TP_SESSION_NAME_MAX)
+		__field(u32, ns)
+		__field(u32, nr)
+	),
+	TP_fast_assign(
+		memcpy(__entry->name, session->name, L2TP_SESSION_NAME_MAX);
+		__entry->ns = session->ns;
+		__entry->nr = session->nr;
+	),
+	TP_printk("%s: ns=%u nr=%u",
+		__entry->name,
+		__entry->ns,
+		__entry->nr)
+);
+
+DEFINE_EVENT(session_seqnum_evt, session_seqnum_update,
+	TP_PROTO(struct l2tp_session *session),
+	TP_ARGS(session)
+);
+
+DEFINE_EVENT(session_seqnum_evt, session_seqnum_reset,
+	TP_PROTO(struct l2tp_session *session),
+	TP_ARGS(session)
+);
+
+DECLARE_EVENT_CLASS(session_pkt_discard_evt,
+	TP_PROTO(struct l2tp_session *session, u32 pkt_ns),
+	TP_ARGS(session, pkt_ns),
+	TP_STRUCT__entry(
+		__array(char, name, L2TP_SESSION_NAME_MAX)
+		__field(u32, pkt_ns)
+		__field(u32, my_nr)
+		__field(u32, reorder_q_len)
+	),
+	TP_fast_assign(
+		memcpy(__entry->name, session->name, L2TP_SESSION_NAME_MAX);
+		__entry->pkt_ns = pkt_ns,
+		__entry->my_nr = session->nr;
+		__entry->reorder_q_len = skb_queue_len(&session->reorder_q);
+	),
+	TP_printk("%s: pkt_ns=%u my_nr=%u reorder_q_len=%u",
+		__entry->name,
+		__entry->pkt_ns,
+		__entry->my_nr,
+		__entry->reorder_q_len)
+);
+
+DEFINE_EVENT(session_pkt_discard_evt, session_pkt_expired,
+	TP_PROTO(struct l2tp_session *session, u32 pkt_ns),
+	TP_ARGS(session, pkt_ns)
+);
+
+DEFINE_EVENT(session_pkt_discard_evt, session_pkt_outside_rx_window,
+	TP_PROTO(struct l2tp_session *session, u32 pkt_ns),
+	TP_ARGS(session, pkt_ns)
+);
+
+DEFINE_EVENT(session_pkt_discard_evt, session_pkt_oos,
+	TP_PROTO(struct l2tp_session *session, u32 pkt_ns),
+	TP_ARGS(session, pkt_ns)
+);
+
 #endif /* _TRACE_L2TP_H */
 
 /* This part must be outside protection */

From 6b7bdcd7ca01d84bb1f51a73f3daa063de0cd270 Mon Sep 17 00:00:00 2001
From: Tom Parkin <tparkin@katalix.com>
Date: Sat, 22 Aug 2020 15:59:06 +0100
Subject: [PATCH 6/9] l2tp: add tracepoints to l2tp_core.c

Add lifetime event tracing for tunnel and session instances, tracking
tunnel and session registration, deletion, and eventual freeing.

Port the data path sequence number debug logging to use trace points
rather than custom debug macros.

Signed-off-by: Tom Parkin <tparkin@katalix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
---
 net/l2tp/l2tp_core.c | 83 +++++++++++++++++---------------------------
 1 file changed, 31 insertions(+), 52 deletions(-)

diff --git a/net/l2tp/l2tp_core.c b/net/l2tp/l2tp_core.c
index aee5b230469f7..d8435b6f6feef 100644
--- a/net/l2tp/l2tp_core.c
+++ b/net/l2tp/l2tp_core.c
@@ -61,6 +61,7 @@
 #include <linux/atomic.h>
 
 #include "l2tp_core.h"
+#include "trace.h"
 
 #define CREATE_TRACE_POINTS
 #include "trace.h"
@@ -154,6 +155,7 @@ l2tp_session_id_hash(struct l2tp_tunnel *tunnel, u32 session_id)
 
 static void l2tp_tunnel_free(struct l2tp_tunnel *tunnel)
 {
+	trace_free_tunnel(tunnel);
 	sock_put(tunnel->sock);
 	/* the tunnel is freed in the socket destructor */
 }
@@ -162,6 +164,8 @@ static void l2tp_session_free(struct l2tp_session *session)
 {
 	struct l2tp_tunnel *tunnel = session->tunnel;
 
+	trace_free_session(session);
+
 	if (tunnel) {
 		if (WARN_ON(tunnel->magic != L2TP_TUNNEL_MAGIC))
 			goto out;
@@ -384,6 +388,8 @@ int l2tp_session_register(struct l2tp_session *session,
 	hlist_add_head(&session->hlist, head);
 	write_unlock_bh(&tunnel->hlist_lock);
 
+	trace_register_session(session);
+
 	return 0;
 
 err_tlock_pnlock:
@@ -412,10 +418,6 @@ static void l2tp_recv_queue_skb(struct l2tp_session *session, struct sk_buff *sk
 	skb_queue_walk_safe(&session->reorder_q, skbp, tmp) {
 		if (L2TP_SKB_CB(skbp)->ns > ns) {
 			__skb_queue_before(&session->reorder_q, skbp, skb);
-			l2tp_dbg(session, L2TP_MSG_SEQ,
-				 "%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));
 			atomic_long_inc(&session->stats.rx_oos_packets);
 			goto out;
 		}
@@ -448,9 +450,7 @@ static void l2tp_recv_dequeue_skb(struct l2tp_session *session, struct sk_buff *
 		/* Bump our Nr */
 		session->nr++;
 		session->nr &= session->nr_max;
-
-		l2tp_dbg(session, L2TP_MSG_SEQ, "%s: updated nr to %hu\n",
-			 session->name, session->nr);
+		trace_session_seqnum_update(session);
 	}
 
 	/* call private receive handler */
@@ -475,37 +475,27 @@ static void l2tp_recv_dequeue(struct l2tp_session *session)
 start:
 	spin_lock_bh(&session->reorder_q.lock);
 	skb_queue_walk_safe(&session->reorder_q, skb, tmp) {
-		if (time_after(jiffies, L2TP_SKB_CB(skb)->expires)) {
+		struct l2tp_skb_cb *cb = L2TP_SKB_CB(skb);
+
+		/* If the packet has been pending on the queue for too long, discard it */
+		if (time_after(jiffies, cb->expires)) {
 			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,
-				 L2TP_SKB_CB(skb)->length, session->nr,
-				 skb_queue_len(&session->reorder_q));
+			trace_session_pkt_expired(session, cb->ns);
 			session->reorder_skip = 1;
 			__skb_unlink(skb, &session->reorder_q);
 			kfree_skb(skb);
 			continue;
 		}
 
-		if (L2TP_SKB_CB(skb)->has_seq) {
+		if (cb->has_seq) {
 			if (session->reorder_skip) {
-				l2tp_dbg(session, L2TP_MSG_SEQ,
-					 "%s: advancing nr to next pkt: %u -> %u",
-					 session->name, session->nr,
-					 L2TP_SKB_CB(skb)->ns);
 				session->reorder_skip = 0;
-				session->nr = L2TP_SKB_CB(skb)->ns;
+				session->nr = cb->ns;
+				trace_session_seqnum_reset(session);
 			}
-			if (L2TP_SKB_CB(skb)->ns != session->nr) {
-				l2tp_dbg(session, L2TP_MSG_SEQ,
-					 "%s: holding oos pkt %u len %d, waiting for %u, reorder_q_len=%d\n",
-					 session->name, L2TP_SKB_CB(skb)->ns,
-					 L2TP_SKB_CB(skb)->length, session->nr,
-					 skb_queue_len(&session->reorder_q));
+			if (cb->ns != session->nr)
 				goto out;
-			}
 		}
 		__skb_unlink(skb, &session->reorder_q);
 
@@ -538,14 +528,13 @@ static int l2tp_seq_check_rx_window(struct l2tp_session *session, u32 nr)
  */
 static int l2tp_recv_data_seq(struct l2tp_session *session, struct sk_buff *skb)
 {
-	if (!l2tp_seq_check_rx_window(session, L2TP_SKB_CB(skb)->ns)) {
+	struct l2tp_skb_cb *cb = L2TP_SKB_CB(skb);
+
+	if (!l2tp_seq_check_rx_window(session, cb->ns)) {
 		/* Packet sequence number is outside allowed window.
 		 * Discard it.
 		 */
-		l2tp_dbg(session, L2TP_MSG_SEQ,
-			 "%s: pkt %u len %d discarded, outside window, nr=%u\n",
-			 session->name, L2TP_SKB_CB(skb)->ns,
-			 L2TP_SKB_CB(skb)->length, session->nr);
+		trace_session_pkt_outside_rx_window(session, cb->ns);
 		goto discard;
 	}
 
@@ -562,10 +551,10 @@ static int l2tp_recv_data_seq(struct l2tp_session *session, struct sk_buff *skb)
 	 * is seen. After nr_oos_count_max in-sequence packets, reset the
 	 * sequence number to re-enable packet reception.
 	 */
-	if (L2TP_SKB_CB(skb)->ns == session->nr) {
+	if (cb->ns == session->nr) {
 		skb_queue_tail(&session->reorder_q, skb);
 	} else {
-		u32 nr_oos = L2TP_SKB_CB(skb)->ns;
+		u32 nr_oos = cb->ns;
 		u32 nr_next = (session->nr_oos + 1) & session->nr_max;
 
 		if (nr_oos == nr_next)
@@ -576,17 +565,10 @@ static int l2tp_recv_data_seq(struct l2tp_session *session, struct sk_buff *skb)
 		session->nr_oos = nr_oos;
 		if (session->nr_oos_count > session->nr_oos_count_max) {
 			session->reorder_skip = 1;
-			l2tp_dbg(session, L2TP_MSG_SEQ,
-				 "%s: %d oos packets received. Resetting sequence numbers\n",
-				 session->name, session->nr_oos_count);
 		}
 		if (!session->reorder_skip) {
 			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,
-				 L2TP_SKB_CB(skb)->length, session->nr,
-				 skb_queue_len(&session->reorder_q));
+			trace_session_pkt_oos(session, cb->ns);
 			goto discard;
 		}
 		skb_queue_tail(&session->reorder_q, skb);
@@ -712,9 +694,7 @@ void l2tp_recv_common(struct l2tp_session *session, struct sk_buff *skb,
 		 * configure it so.
 		 */
 		if (!session->lns_mode && !session->send_seq) {
-			l2tp_info(session, L2TP_MSG_SEQ,
-				  "%s: requested to enable seq numbers by LNS\n",
-				  session->name);
+			trace_session_seqnum_lns_enable(session);
 			session->send_seq = 1;
 			l2tp_session_set_header_len(session, tunnel->version);
 		}
@@ -735,9 +715,7 @@ void l2tp_recv_common(struct l2tp_session *session, struct sk_buff *skb,
 		 * LAC is broken. Discard the frame.
 		 */
 		if (!session->lns_mode && session->send_seq) {
-			l2tp_info(session, L2TP_MSG_SEQ,
-				  "%s: requested to disable seq numbers by LNS\n",
-				  session->name);
+			trace_session_seqnum_lns_disable(session);
 			session->send_seq = 0;
 			l2tp_session_set_header_len(session, tunnel->version);
 		} else if (session->send_seq) {
@@ -961,8 +939,7 @@ static int l2tp_build_l2tpv2_header(struct l2tp_session *session, void *buf)
 		*bufp++ = 0;
 		session->ns++;
 		session->ns &= 0xffff;
-		l2tp_dbg(session, L2TP_MSG_SEQ, "%s: updated ns to %u\n",
-			 session->name, session->ns);
+		trace_session_seqnum_update(session);
 	}
 
 	return bufp - optr;
@@ -998,9 +975,7 @@ static int l2tp_build_l2tpv3_header(struct l2tp_session *session, void *buf)
 			l2h = 0x40000000 | session->ns;
 			session->ns++;
 			session->ns &= 0xffffff;
-			l2tp_dbg(session, L2TP_MSG_SEQ,
-				 "%s: updated ns to %u\n",
-				 session->name, session->ns);
+			trace_session_seqnum_update(session);
 		}
 
 		*((__be32 *)bufp) = htonl(l2h);
@@ -1540,6 +1515,8 @@ int l2tp_tunnel_register(struct l2tp_tunnel *tunnel, struct net *net,
 				   "l2tp_sock");
 	sk->sk_allocation = GFP_ATOMIC;
 
+	trace_register_tunnel(tunnel);
+
 	if (tunnel->fd >= 0)
 		sockfd_put(sock);
 
@@ -1560,6 +1537,7 @@ EXPORT_SYMBOL_GPL(l2tp_tunnel_register);
 void l2tp_tunnel_delete(struct l2tp_tunnel *tunnel)
 {
 	if (!test_and_set_bit(0, &tunnel->dead)) {
+		trace_delete_tunnel(tunnel);
 		l2tp_tunnel_inc_refcount(tunnel);
 		queue_work(l2tp_wq, &tunnel->del_work);
 	}
@@ -1571,6 +1549,7 @@ void l2tp_session_delete(struct l2tp_session *session)
 	if (test_and_set_bit(0, &session->dead))
 		return;
 
+	trace_delete_session(session);
 	l2tp_session_unhash(session);
 	l2tp_session_queue_purge(session);
 	if (session->session_close)

From ac6ebaf06e2c1bf6e42e35b35ded8b6d576d24d6 Mon Sep 17 00:00:00 2001
From: Tom Parkin <tparkin@katalix.com>
Date: Sat, 22 Aug 2020 15:59:07 +0100
Subject: [PATCH 7/9] l2tp: remove custom logging macros

All l2tp's informational and warning logging is now carried out using
standard kernel APIs.

Debugging information is now handled using tracepoints.

Now that no code is using the custom logging macros, remove them from
l2tp_core.h.

Signed-off-by: Tom Parkin <tparkin@katalix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
---
 net/l2tp/l2tp_core.h | 13 -------------
 1 file changed, 13 deletions(-)

diff --git a/net/l2tp/l2tp_core.h b/net/l2tp/l2tp_core.h
index 835c4645a0ecd..7a06ac135a9b4 100644
--- a/net/l2tp/l2tp_core.h
+++ b/net/l2tp/l2tp_core.h
@@ -339,19 +339,6 @@ static inline int l2tp_v3_ensure_opt_in_linear(struct l2tp_session *session, str
 	return 0;
 }
 
-#define l2tp_printk(ptr, type, func, fmt, ...)				\
-do {									\
-	if (((ptr)->debug) & (type))					\
-		func(fmt, ##__VA_ARGS__);				\
-} while (0)
-
-#define l2tp_warn(ptr, type, fmt, ...)					\
-	l2tp_printk(ptr, type, pr_warn, fmt, ##__VA_ARGS__)
-#define l2tp_info(ptr, type, fmt, ...)					\
-	l2tp_printk(ptr, type, pr_info, fmt, ##__VA_ARGS__)
-#define l2tp_dbg(ptr, type, fmt, ...)					\
-	l2tp_printk(ptr, type, pr_debug, fmt, ##__VA_ARGS__)
-
 #define MODULE_ALIAS_L2TP_PWTYPE(type) \
 	MODULE_ALIAS("net-l2tp-type-" __stringify(type))
 

From eee049c0ef5b5b433f36841801e34c21c9f82a23 Mon Sep 17 00:00:00 2001
From: Tom Parkin <tparkin@katalix.com>
Date: Sat, 22 Aug 2020 15:59:08 +0100
Subject: [PATCH 8/9] l2tp: remove tunnel and session debug flags field

The l2tp subsystem now uses standard kernel logging APIs for
informational and warning messages, and tracepoints for debug
information.

Now that the tunnel and session debug flags are unused, remove the field
from the core structures.

Various system calls (in the case of l2tp_ppp) and netlink messages
handle the getting and setting of debug flags.  To avoid userspace
breakage don't modify the API of these calls; simply ignore set
requests, and send dummy data for get requests.

Signed-off-by: Tom Parkin <tparkin@katalix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
---
 include/uapi/linux/if_pppol2tp.h |  2 +-
 include/uapi/linux/l2tp.h        |  6 ++++--
 net/l2tp/l2tp_core.c             |  8 --------
 net/l2tp/l2tp_core.h             |  4 ----
 net/l2tp/l2tp_debugfs.c          |  4 ++--
 net/l2tp/l2tp_netlink.c          | 16 ++--------------
 net/l2tp/l2tp_ppp.c              | 15 ++++++++-------
 7 files changed, 17 insertions(+), 38 deletions(-)

diff --git a/include/uapi/linux/if_pppol2tp.h b/include/uapi/linux/if_pppol2tp.h
index 060b4d1f31296..a91044328bc90 100644
--- a/include/uapi/linux/if_pppol2tp.h
+++ b/include/uapi/linux/if_pppol2tp.h
@@ -75,7 +75,7 @@ struct pppol2tpv3in6_addr {
 };
 
 /* Socket options:
- * DEBUG	- bitmask of debug message categories
+ * DEBUG	- bitmask of debug message categories (not used)
  * SENDSEQ	- 0 => don't send packets with sequence numbers
  *		  1 => send packets with sequence numbers
  * RECVSEQ	- 0 => receive packet sequence numbers are optional
diff --git a/include/uapi/linux/l2tp.h b/include/uapi/linux/l2tp.h
index 61158f5a1a5bc..88a0d32b8c07f 100644
--- a/include/uapi/linux/l2tp.h
+++ b/include/uapi/linux/l2tp.h
@@ -108,7 +108,7 @@ enum {
 	L2TP_ATTR_VLAN_ID,		/* u16 (not used) */
 	L2TP_ATTR_COOKIE,		/* 0, 4 or 8 bytes */
 	L2TP_ATTR_PEER_COOKIE,		/* 0, 4 or 8 bytes */
-	L2TP_ATTR_DEBUG,		/* u32, enum l2tp_debug_flags */
+	L2TP_ATTR_DEBUG,		/* u32, enum l2tp_debug_flags (not used) */
 	L2TP_ATTR_RECV_SEQ,		/* u8 */
 	L2TP_ATTR_SEND_SEQ,		/* u8 */
 	L2TP_ATTR_LNS_MODE,		/* u8 */
@@ -177,7 +177,9 @@ enum l2tp_seqmode {
 };
 
 /**
- * enum l2tp_debug_flags - debug message categories for L2TP tunnels/sessions
+ * enum l2tp_debug_flags - debug message categories for L2TP tunnels/sessions.
+ *
+ * Unused.
  *
  * @L2TP_MSG_DEBUG: verbose debug (if compiled in)
  * @L2TP_MSG_CONTROL: userspace - kernel interface
diff --git a/net/l2tp/l2tp_core.c b/net/l2tp/l2tp_core.c
index d8435b6f6feef..560c687f54579 100644
--- a/net/l2tp/l2tp_core.c
+++ b/net/l2tp/l2tp_core.c
@@ -1401,16 +1401,12 @@ int l2tp_tunnel_create(struct net *net, int fd, int version, u32 tunnel_id, u32
 	tunnel->version = version;
 	tunnel->tunnel_id = tunnel_id;
 	tunnel->peer_tunnel_id = peer_tunnel_id;
-	tunnel->debug = L2TP_DEFAULT_DEBUG_FLAGS;
 
 	tunnel->magic = L2TP_TUNNEL_MAGIC;
 	sprintf(&tunnel->name[0], "tunl %u", tunnel_id);
 	rwlock_init(&tunnel->hlist_lock);
 	tunnel->acpt_newsess = true;
 
-	if (cfg)
-		tunnel->debug = cfg->debug;
-
 	tunnel->encap = encap;
 
 	refcount_set(&tunnel->ref_count, 1);
@@ -1608,12 +1604,8 @@ struct l2tp_session *l2tp_session_create(int priv_size, struct l2tp_tunnel *tunn
 		INIT_HLIST_NODE(&session->hlist);
 		INIT_HLIST_NODE(&session->global_hlist);
 
-		/* Inherit debug options from tunnel */
-		session->debug = tunnel->debug;
-
 		if (cfg) {
 			session->pwtype = cfg->pw_type;
-			session->debug = cfg->debug;
 			session->send_seq = cfg->send_seq;
 			session->recv_seq = cfg->recv_seq;
 			session->lns_mode = cfg->lns_mode;
diff --git a/net/l2tp/l2tp_core.h b/net/l2tp/l2tp_core.h
index 7a06ac135a9b4..07249c5f22ef6 100644
--- a/net/l2tp/l2tp_core.h
+++ b/net/l2tp/l2tp_core.h
@@ -51,7 +51,6 @@ struct l2tp_session_cfg {
 	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 */
@@ -98,7 +97,6 @@ struct l2tp_session {
 	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;
@@ -132,7 +130,6 @@ struct l2tp_session {
 
 /* L2TP tunnel configuration */
 struct l2tp_tunnel_cfg {
-	int			debug;		/* bitmask of debug message categories */
 	enum l2tp_encap_type	encap;
 
 	/* Used only for kernel-created sockets */
@@ -173,7 +170,6 @@ struct l2tp_tunnel {
 	int			version;	/* 2=>L2TPv2, 3=>L2TPv3 */
 
 	char			name[L2TP_TUNNEL_NAME_MAX]; /* for logging */
-	int			debug;		/* bitmask of debug message categories */
 	enum l2tp_encap_type	encap;
 	struct l2tp_stats	stats;
 
diff --git a/net/l2tp/l2tp_debugfs.c b/net/l2tp/l2tp_debugfs.c
index 96cb9601c21b7..bca75bef82828 100644
--- a/net/l2tp/l2tp_debugfs.c
+++ b/net/l2tp/l2tp_debugfs.c
@@ -167,7 +167,7 @@ static void l2tp_dfs_seq_tunnel_show(struct seq_file *m, void *v)
 		   tunnel->sock ? refcount_read(&tunnel->sock->sk_refcnt) : 0,
 		   refcount_read(&tunnel->ref_count));
 	seq_printf(m, " %08x rx %ld/%ld/%ld rx %ld/%ld/%ld\n",
-		   tunnel->debug,
+		   0,
 		   atomic_long_read(&tunnel->stats.tx_packets),
 		   atomic_long_read(&tunnel->stats.tx_bytes),
 		   atomic_long_read(&tunnel->stats.tx_errors),
@@ -192,7 +192,7 @@ static void l2tp_dfs_seq_session_show(struct seq_file *m, void *v)
 		   session->recv_seq ? 'R' : '-',
 		   session->send_seq ? 'S' : '-',
 		   session->lns_mode ? "LNS" : "LAC",
-		   session->debug,
+		   0,
 		   jiffies_to_msecs(session->reorder_timeout));
 	seq_printf(m, "   offset 0 l2specific %hu/%hu\n",
 		   session->l2specific_type, l2tp_get_l2specific_len(session));
diff --git a/net/l2tp/l2tp_netlink.c b/net/l2tp/l2tp_netlink.c
index def78eebca4c5..31a1e27eab209 100644
--- a/net/l2tp/l2tp_netlink.c
+++ b/net/l2tp/l2tp_netlink.c
@@ -229,9 +229,6 @@ static int l2tp_nl_cmd_tunnel_create(struct sk_buff *skb, struct genl_info *info
 			goto out;
 	}
 
-	if (attrs[L2TP_ATTR_DEBUG])
-		cfg.debug = nla_get_u32(attrs[L2TP_ATTR_DEBUG]);
-
 	ret = -EINVAL;
 	switch (cfg.encap) {
 	case L2TP_ENCAPTYPE_UDP:
@@ -307,9 +304,6 @@ static int l2tp_nl_cmd_tunnel_modify(struct sk_buff *skb, struct genl_info *info
 		goto out;
 	}
 
-	if (info->attrs[L2TP_ATTR_DEBUG])
-		tunnel->debug = nla_get_u32(info->attrs[L2TP_ATTR_DEBUG]);
-
 	ret = l2tp_tunnel_notify(&l2tp_nl_family, info,
 				 tunnel, L2TP_CMD_TUNNEL_MODIFY);
 
@@ -400,7 +394,7 @@ static int l2tp_nl_tunnel_send(struct sk_buff *skb, u32 portid, u32 seq, int fla
 	if (nla_put_u8(skb, L2TP_ATTR_PROTO_VERSION, tunnel->version) ||
 	    nla_put_u32(skb, L2TP_ATTR_CONN_ID, tunnel->tunnel_id) ||
 	    nla_put_u32(skb, L2TP_ATTR_PEER_CONN_ID, tunnel->peer_tunnel_id) ||
-	    nla_put_u32(skb, L2TP_ATTR_DEBUG, tunnel->debug) ||
+	    nla_put_u32(skb, L2TP_ATTR_DEBUG, 0) ||
 	    nla_put_u16(skb, L2TP_ATTR_ENCAP_TYPE, tunnel->encap))
 		goto nla_put_failure;
 
@@ -605,9 +599,6 @@ static int l2tp_nl_cmd_session_create(struct sk_buff *skb, struct genl_info *inf
 			cfg.ifname = nla_data(info->attrs[L2TP_ATTR_IFNAME]);
 	}
 
-	if (info->attrs[L2TP_ATTR_DEBUG])
-		cfg.debug = nla_get_u32(info->attrs[L2TP_ATTR_DEBUG]);
-
 	if (info->attrs[L2TP_ATTR_RECV_SEQ])
 		cfg.recv_seq = nla_get_u8(info->attrs[L2TP_ATTR_RECV_SEQ]);
 
@@ -689,9 +680,6 @@ static int l2tp_nl_cmd_session_modify(struct sk_buff *skb, struct genl_info *inf
 		goto out;
 	}
 
-	if (info->attrs[L2TP_ATTR_DEBUG])
-		session->debug = nla_get_u32(info->attrs[L2TP_ATTR_DEBUG]);
-
 	if (info->attrs[L2TP_ATTR_RECV_SEQ])
 		session->recv_seq = nla_get_u8(info->attrs[L2TP_ATTR_RECV_SEQ]);
 
@@ -730,7 +718,7 @@ static int l2tp_nl_session_send(struct sk_buff *skb, u32 portid, u32 seq, int fl
 	    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_DEBUG, session->debug) ||
+	    nla_put_u32(skb, L2TP_ATTR_DEBUG, 0) ||
 	    nla_put_u16(skb, L2TP_ATTR_PW_TYPE, session->pwtype))
 		goto nla_put_failure;
 
diff --git a/net/l2tp/l2tp_ppp.c b/net/l2tp/l2tp_ppp.c
index bd6bb17dfadbb..450637ffa5577 100644
--- a/net/l2tp/l2tp_ppp.c
+++ b/net/l2tp/l2tp_ppp.c
@@ -702,7 +702,6 @@ static int pppol2tp_connect(struct socket *sock, struct sockaddr *uservaddr,
 		if (!tunnel) {
 			struct l2tp_tunnel_cfg tcfg = {
 				.encap = L2TP_ENCAPTYPE_UDP,
-				.debug = 0,
 			};
 
 			/* Prevent l2tp_tunnel_register() from trying to set up
@@ -1147,7 +1146,7 @@ static int pppol2tp_tunnel_setsockopt(struct sock *sk,
 
 	switch (optname) {
 	case PPPOL2TP_SO_DEBUG:
-		tunnel->debug = val;
+		/* Tunnel debug flags option is deprecated */
 		break;
 
 	default:
@@ -1199,7 +1198,7 @@ static int pppol2tp_session_setsockopt(struct sock *sk,
 		break;
 
 	case PPPOL2TP_SO_DEBUG:
-		session->debug = val;
+		/* Session debug flags option is deprecated */
 		break;
 
 	case PPPOL2TP_SO_REORDERTO:
@@ -1271,7 +1270,8 @@ static int pppol2tp_tunnel_getsockopt(struct sock *sk,
 
 	switch (optname) {
 	case PPPOL2TP_SO_DEBUG:
-		*val = tunnel->debug;
+		/* Tunnel debug flags option is deprecated */
+		*val = 0;
 		break;
 
 	default:
@@ -1304,7 +1304,8 @@ static int pppol2tp_session_getsockopt(struct sock *sk,
 		break;
 
 	case PPPOL2TP_SO_DEBUG:
-		*val = session->debug;
+		/* Session debug flags option is deprecated */
+		*val = 0;
 		break;
 
 	case PPPOL2TP_SO_REORDERTO:
@@ -1496,7 +1497,7 @@ static void pppol2tp_seq_tunnel_show(struct seq_file *m, void *v)
 		   (tunnel == tunnel->sock->sk_user_data) ? 'Y' : 'N',
 		   refcount_read(&tunnel->ref_count) - 1);
 	seq_printf(m, " %08x %ld/%ld/%ld %ld/%ld/%ld\n",
-		   tunnel->debug,
+		   0,
 		   atomic_long_read(&tunnel->stats.tx_packets),
 		   atomic_long_read(&tunnel->stats.tx_bytes),
 		   atomic_long_read(&tunnel->stats.tx_errors),
@@ -1542,7 +1543,7 @@ static void pppol2tp_seq_session_show(struct seq_file *m, void *v)
 		   session->recv_seq ? 'R' : '-',
 		   session->send_seq ? 'S' : '-',
 		   session->lns_mode ? "LNS" : "LAC",
-		   session->debug,
+		   0,
 		   jiffies_to_msecs(session->reorder_timeout));
 	seq_printf(m, "   %hu/%hu %ld/%ld/%ld %ld/%ld/%ld\n",
 		   session->nr, session->ns,

From 9d048e5e6628d821a608c955ef120722c0752e19 Mon Sep 17 00:00:00 2001
From: Tom Parkin <tparkin@katalix.com>
Date: Sat, 22 Aug 2020 15:59:09 +0100
Subject: [PATCH 9/9] docs: networking: add tracepoint info to l2tp.rst

Update l2tp.rst to:

 * remove information about the obsolete debug flags and their use
 * include information about tracepoints for l2tp

Signed-off-by: Tom Parkin <tparkin@katalix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
---
 Documentation/networking/l2tp.rst | 37 ++++++++++++-------------------
 1 file changed, 14 insertions(+), 23 deletions(-)

diff --git a/Documentation/networking/l2tp.rst b/Documentation/networking/l2tp.rst
index 693ea0e3ec26f..498b382d25a0b 100644
--- a/Documentation/networking/l2tp.rst
+++ b/Documentation/networking/l2tp.rst
@@ -455,31 +455,16 @@ l2tp help`` for more information.
 Debugging
 ---------
 
-The L2TP subsystem offers a debug scheme where kernel trace messages
-may be optionally enabled per tunnel and per session. Care is needed
-when debugging a live system since the messages are not rate-limited
-and a busy system could be swamped. Userspace uses setsockopt on the
-PPPoX socket to set a debug mask, or ``L2TP_ATTR_DEBUG`` in netlink
-Create and Modify commands.
+The L2TP subsystem offers a range of debugging interfaces through the
+debugfs filesystem.
 
-The following debug mask bits are defined:-
-
-================  ==============================
-L2TP_MSG_DEBUG    verbose debug (if compiled in)
-L2TP_MSG_CONTROL  userspace - kernel interface
-L2TP_MSG_SEQ      sequence numbers handling
-L2TP_MSG_DATA     data packets
-================  ==============================
-
-Sessions inherit default debug flags from the parent tunnel.
-
-If enabled, files under a l2tp debugfs directory can be used to dump
-kernel state about L2TP tunnels and sessions. To access it, the
-debugfs filesystem must first be mounted::
+To access these interfaces, the debugfs filesystem must first be mounted::
 
     # mount -t debugfs debugfs /debug
 
-Files under the l2tp directory can then be accessed::
+Files under the l2tp directory can then be accessed, providing a summary
+of the current population of tunnel and session contexts existing in the
+kernel::
 
     # cat /debug/l2tp/tunnels
 
@@ -488,8 +473,14 @@ state information because the file format is subject to change. It is
 implemented to provide extra debug information to help diagnose
 problems. Applications should instead use the netlink API.
 
-/proc/net/pppol2tp is also provided for backwards compatibility with
-the original pppol2tp code. It lists information about L2TPv2
+In addition the L2TP subsystem implements tracepoints using the standard
+kernel event tracing API.  The available L2TP events can be reviewed as
+follows::
+
+    # find /debug/tracing/events/l2tp
+
+Finally, /proc/net/pppol2tp is also provided for backwards compatibility
+with the original pppol2tp code. It lists information about L2TPv2
 tunnels and sessions only. Its use is discouraged.
 
 Internal Implementation