netdev - Re: [PATCH v2 net-next] net/tcp: trace all TCP/IP state transition with tcp_set

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Message-ID: <3F850155-217D-4133-A5CE-4F79DA52B646@fb.com>
Date:   Sat, 18 Nov 2017 18:49:00 +0000
From:   Song Liu <songliubraving@...com>
To:     Yafang Shao <laoar.shao@...il.com>,
        Brendan Gregg <bgregg@...flix.com>
CC:     "davem@...emloft.net" <davem@...emloft.net>,
        "kuznet@....inr.ac.ru" <kuznet@....inr.ac.ru>,
        "yoshfuji@...ux-ipv6.org" <yoshfuji@...ux-ipv6.org>,
        "rostedt@...dmis.org" <rostedt@...dmis.org>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 net-next] net/tcp: trace all TCP/IP state transition
 with tcp_set_state tracepoint


> On Nov 18, 2017, at 7:32 AM, Yafang Shao <laoar.shao@...il.com> wrote:
> 
> 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@...il.com>
> ---
> include/net/tcp.h               |  2 ++
> net/ipv4/inet_connection_sock.c |  6 +++---
> net/ipv4/inet_hashtables.c      |  2 +-
> net/ipv4/tcp.c                  | 12 ++++++++++++
> 4 files changed, 18 insertions(+), 4 deletions(-)
> 
> diff --git a/include/net/tcp.h b/include/net/tcp.h
> index 85ea578..4f2d015 100644
> --- a/include/net/tcp.h
> +++ b/include/net/tcp.h
> @@ -1247,6 +1247,8 @@ static inline bool tcp_checksum_complete(struct sk_buff *skb)
> 	"Close Wait","Last ACK","Listen","Closing"
> };
> #endif
> +void __sk_state_store(struct sock *sk, int newstate);
> +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..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);
> 	}
> diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
> index bf97317..2bc7e04 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;
> -- 
> 1.8.3.1
> 

+ Brendan