[PATCH v3 net-next] net/tcp: trace all TCP/IP state transition with tcp_set_state tracepoint

[Yafang Shao]

The TCP/IP transition from TCP_LISTEN to TCP_SYN_RECV and some other
transitions are not traced with tcp_set_state tracepoint.

In order to trace the whole tcp lifespans, two helpers are introduced,
void __tcp_set_state(struct sock *sk, int state);
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>
Acked-by: Song Liu <songliubraving@xxxxxx>
---
v2->v3: Per suggestion from Marcelo Ricardo Leitner, inverting  __
		to sk_state_store. 
---
 include/net/sock.h              |  7 +++++--
 include/net/tcp.h               |  1 +
 net/ipv4/inet_connection_sock.c |  4 ++--
 net/ipv4/inet_hashtables.c      |  2 +-
 net/ipv4/tcp.c                  | 14 +++++++++++++-
 5 files changed, 22 insertions(+), 6 deletions(-)

diff --git a/include/net/sock.h b/include/net/sock.h
index 79e1a2c..e89a098 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -2349,18 +2349,21 @@ static inline int sk_state_load(const struct sock *sk)
 }
 
 /**
- * sk_state_store - update sk->sk_state
+ * __sk_state_store - update sk->sk_state
  * @sk: socket pointer
  * @newstate: new state
  *
  * Paired with sk_state_load(). Should be used in contexts where
  * state change might impact lockless readers.
  */
-static inline void sk_state_store(struct sock *sk, int newstate)
+static inline void __sk_state_store(struct sock *sk, int newstate)
 {
 	smp_store_release(&sk->sk_state, newstate);
 }
 
+/* For tcp_set_state tracepoint */
+void sk_state_store(struct sock *sk, int newstate);
+
 void sock_enable_timestamp(struct sock *sk, int flag);
 int sock_get_timestamp(struct sock *, struct timeval __user *);
 int sock_get_timestampns(struct sock *, struct timespec __user *);
diff --git a/include/net/tcp.h b/include/net/tcp.h
index 4e09398..cc43ce9 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -1247,6 +1247,7 @@ static inline bool tcp_checksum_complete(struct sk_buff *skb)
 	"Close Wait","Last ACK","Listen","Closing"
 };
 #endif
+void __tcp_set_state(struct sock *sk, int state);
 void tcp_set_state(struct sock *sk, int state);
 
 void tcp_done(struct sock *sk);
diff --git a/net/ipv4/inet_connection_sock.c b/net/ipv4/inet_connection_sock.c
index 4ca46dc..74523c4 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;
@@ -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 f6f5810..b24cc12 100644
--- a/net/ipv4/inet_hashtables.c
+++ b/net/ipv4/inet_hashtables.c
@@ -544,7 +544,7 @@ 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);
 	}
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 1803116..4ade887 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -2036,6 +2036,18 @@ int tcp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, int nonblock,
 }
 EXPORT_SYMBOL(tcp_recvmsg);
 
+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_set_state(struct sock *sk, int state)
+{
+	trace_tcp_set_state(sk, sk->sk_state, state);
+	sk->sk_state = state;
+}
+
 void tcp_set_state(struct sock *sk, int state)
 {
 	int oldstate = sk->sk_state;
@@ -2065,7 +2077,7 @@ void tcp_set_state(struct sock *sk, int state)
 	/* Change state AFTER socket is unhashed to avoid closed
 	 * socket sitting in hash tables.
 	 */
-	sk_state_store(sk, state);
+	__sk_state_store(sk, state);
 
 #ifdef STATE_TRACE
 	SOCK_DEBUG(sk, "TCP sk=%p, State %s -> %s\n", sk, statename[oldstate], statename[state]);
-- 
1.8.3.1