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l2tp: add tracepoints to l2tp_core.c
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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>
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Tom Parkin authored and David S. Miller committed Aug 22, 2020
1 parent 2a03dd8 commit 6b7bdcd
Showing 1 changed file with 31 additions and 52 deletions.
83 changes: 31 additions & 52 deletions net/l2tp/l2tp_core.c
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Original file line number Diff line number Diff line change
Expand Up @@ -61,6 +61,7 @@
#include <linux/atomic.h>

#include "l2tp_core.h"
#include "trace.h"

#define CREATE_TRACE_POINTS
#include "trace.h"
Expand Down Expand Up @@ -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 */
}
Expand All @@ -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;
Expand Down Expand Up @@ -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:
Expand Down Expand Up @@ -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;
}
Expand Down Expand Up @@ -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 */
Expand All @@ -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);

Expand Down Expand Up @@ -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;
}

Expand All @@ -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)
Expand All @@ -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);
Expand Down Expand Up @@ -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);
}
Expand All @@ -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) {
Expand Down Expand Up @@ -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;
Expand Down Expand Up @@ -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);
Expand Down Expand Up @@ -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);

Expand All @@ -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);
}
Expand All @@ -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)
Expand Down

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