[PATCH net-next 1/2] net/tcp: track all TCP/IP state transition in tcp_set_state

[Yafang Shao]

The TCP/IP transition from TCP_LISTEN to TCP_SYN_RECV isn't traced in
the tcp_set_state tracepoint.

In order to trace the whole tcp lifespans, two helpers are introduced,
static inline void __tcp_set_state(struct sock *sk, int state)
static inline void __sk_state_store(struct sock *sk, int newstate)

When do TCP/IP state transition, we should use these two helpers or use
tcp_set_state() other than assigning a value to sk_state directly.

Signed-off-by: Yafang Shao <laoar.shao@xxxxxxxxx>
---
 include/net/tcp.h               | 16 ++++++++++++++++
 net/ipv4/inet_connection_sock.c |  6 +++---
 net/ipv4/inet_hashtables.c      |  2 +-
 3 files changed, 20 insertions(+), 4 deletions(-)

diff --git a/include/net/tcp.h b/include/net/tcp.h
index babfd4d..c1d57d0 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -46,6 +46,7 @@
 #include <linux/seq_file.h>
 #include <linux/memcontrol.h>
 #include <linux/bpf-cgroup.h>
+#include <trace/events/tcp.h>
 
 extern struct inet_hashinfo tcp_hashinfo;
 
@@ -1263,6 +1264,21 @@ static inline bool tcp_checksum_complete(struct sk_buff *skb)
 #endif
 void tcp_set_state(struct sock *sk, int state);
 
+/*
+ * To trace TCP/IP state transition.
+ */
+static inline void __tcp_set_state(struct sock *sk, int state)
+{
+	trace_tcp_set_state(sk, sk->sk_state, state);
+	sk->sk_state = state;
+}
+
+static inline void __sk_state_store(struct sock *sk, int newstate)
+{
+	trace_tcp_set_state(sk, sk->sk_state, newstate);
+	sk_state_store(sk, newstate);
+}
+
 void tcp_done(struct sock *sk);
 
 int tcp_abort(struct sock *sk, int err);
diff --git a/net/ipv4/inet_connection_sock.c b/net/ipv4/inet_connection_sock.c
index 4ca46dc..f3967f1 100644
--- a/net/ipv4/inet_connection_sock.c
+++ b/net/ipv4/inet_connection_sock.c
@@ -783,7 +783,7 @@ struct sock *inet_csk_clone_lock(const struct sock *sk,
 	if (newsk) {
 		struct inet_connection_sock *newicsk = inet_csk(newsk);
 
-		newsk->sk_state = TCP_SYN_RECV;
+		__tcp_set_state(newsk, TCP_SYN_RECV);
 		newicsk->icsk_bind_hash = NULL;
 
 		inet_sk(newsk)->inet_dport = inet_rsk(req)->ir_rmt_port;
@@ -877,7 +877,7 @@ int inet_csk_listen_start(struct sock *sk, int backlog)
 	 * It is OK, because this socket enters to hash table only
 	 * after validation is complete.
 	 */
-	sk_state_store(sk, TCP_LISTEN);
+	__sk_state_store(sk, TCP_LISTEN);
 	if (!sk->sk_prot->get_port(sk, inet->inet_num)) {
 		inet->inet_sport = htons(inet->inet_num);
 
@@ -888,7 +888,7 @@ int inet_csk_listen_start(struct sock *sk, int backlog)
 			return 0;
 	}
 
-	sk->sk_state = TCP_CLOSE;
+	__tcp_set_state(sk, TCP_CLOSE);
 	return err;
 }
 EXPORT_SYMBOL_GPL(inet_csk_listen_start);
diff --git a/net/ipv4/inet_hashtables.c b/net/ipv4/inet_hashtables.c
index e7d15fb..72c15b6 100644
--- a/net/ipv4/inet_hashtables.c
+++ b/net/ipv4/inet_hashtables.c
@@ -430,7 +430,7 @@ bool inet_ehash_nolisten(struct sock *sk, struct sock *osk)
 		sock_prot_inuse_add(sock_net(sk), sk->sk_prot, 1);
 	} else {
 		percpu_counter_inc(sk->sk_prot->orphan_count);
-		sk->sk_state = TCP_CLOSE;
+		__tcp_set_state(sk, TCP_CLOSE);
 		sock_set_flag(sk, SOCK_DEAD);
 		inet_csk_destroy_sock(sk);
 	}
-- 
1.8.3.1