Re: [PATCH v5 net-next] net/tcp: trace all TCP/IP state transition with tcp_set_state tracepoint

[Yafang Shao <laoar.shao@gmail.com>]

2017-12-08 4:02 GMT+08:00 Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>:
> On Thu, Dec 07, 2017 at 02:10:42PM +0000, Yafang Shao 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 sk_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@gmail.com>
>> Acked-by: Song Liu <songliubraving@fb.com>
>> Reviewed-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
>> Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
>> ---
>> v4->v5: Trace only TCP sockets, whatever it is stream socket or raw socket.
>> v3->v4: Do not trace DCCP socket
>> v2->v3: Per suggestion from Marcelo Ricardo Leitner, inverting  __
>>                to sk_state_store.
>> ---
>>  include/net/sock.h              |  8 ++++++--
>>  net/core/sock.c                 | 15 +++++++++++++++
>>  net/ipv4/inet_connection_sock.c |  5 +++--
>>  net/ipv4/inet_hashtables.c      |  2 +-
>>  net/ipv4/tcp.c                  |  2 +-
>>  5 files changed, 26 insertions(+), 6 deletions(-)
>>
>> diff --git a/include/net/sock.h b/include/net/sock.h
>> index 79e1a2c..1cf7685 100644
>> --- a/include/net/sock.h
>> +++ b/include/net/sock.h
>> @@ -2349,18 +2349,22 @@ 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 sk_set_state(struct sock *sk, int state);
>> +
>>  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/net/core/sock.c b/net/core/sock.c
>> index c0b5b2f..61841a2 100644
>> --- a/net/core/sock.c
>> +++ b/net/core/sock.c
>> @@ -138,6 +138,7 @@
>>  #include <net/sock_reuseport.h>
>>
>>  #include <trace/events/sock.h>
>> +#include <trace/events/tcp.h>
>>
>>  #include <net/tcp.h>
>>  #include <net/busy_poll.h>
>> @@ -2859,6 +2860,20 @@ int sock_get_timestampns(struct sock *sk, struct timespec __user *userstamp)
>>  }
>>  EXPORT_SYMBOL(sock_get_timestampns);
>>
>> +void sk_state_store(struct sock *sk, int newstate)
>> +{
>> +     if (sk->sk_protocol == IPPROTO_TCP)
>> +             trace_tcp_set_state(sk, sk->sk_state, newstate);
>
> I think this is going in the wrong way. When Dave said to not define a
> sock generic function in tcp code on v3, you moved it all from tcp.h
> to sock.h. But now sock.h gets to deal with more tcp code, which also
> isn't nice.
>
> Instead, if you move it back to tcp.h but rename the function to
> tcp_state_store (instead of the original sk_state_store), it won't be
> a generic sock code and will fit nicely into tcp.h.
>
> You may then even keep sk_state_store() as it is now, and just define
> tcp_state_store():
>
> tcp_state_store()
> {
>         trace_tcp_...();
>         sk_state_store();
> }
>
> Making it very clear that this code is only to be used by tcp stack.
>

Then we have to do bellow 'if' test in inet_connection_sock.c and
/inet_hashtables.

if (sk->sk_protocol == IPPROTO_TCP)
    tcp_state_store(sk, TCP_CLOSE)
else
    sk->sk_state = TCP_CLOSE;

And same code about other changes.

Is that proper ?


>> +     __sk_state_store(sk, newstate);
>> +}
>> +
>> +void sk_set_state(struct sock *sk, int state)
>
> Same about this one.
>
> Dave?
>
>> +{
>> +     if (sk->sk_protocol == IPPROTO_TCP)
>> +             trace_tcp_set_state(sk, sk->sk_state, state);
>> +     sk->sk_state = state;
>> +}
>> +
>>  void sock_enable_timestamp(struct sock *sk, int flag)
>>  {
>>       if (!sock_flag(sk, flag)) {
>> diff --git a/net/ipv4/inet_connection_sock.c b/net/ipv4/inet_connection_sock.c
>> index 4ca46dc..41f9c87 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;
>> +             sk_set_state(newsk, TCP_SYN_RECV);
>>               newicsk->icsk_bind_hash = NULL;
>>
>>               inet_sk(newsk)->inet_dport = inet_rsk(req)->ir_rmt_port;
>> @@ -888,7 +888,8 @@ int inet_csk_listen_start(struct sock *sk, int backlog)
>>                       return 0;
>>       }
>>
>> -     sk->sk_state = TCP_CLOSE;
>> +     sk_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..5973693 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;
>> +             sk_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..ac98dc6 100644
>> --- a/net/ipv4/tcp.c
>> +++ b/net/ipv4/tcp.c
>> @@ -2065,7 +2065,7 @@ 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
>>