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Date: Fri, 8 Dec 2017 09:41:10 +0800
From: Yafang Shao <laoar.shao@...il.com>
To: Marcelo Ricardo Leitner <marcelo.leitner@...il.com>
Cc: David Miller <davem@...emloft.net>,
Song Liu <songliubraving@...com>,
Alexey Kuznetsov <kuznet@....inr.ac.ru>,
yoshfuji@...ux-ipv6.org, Steven Rostedt <rostedt@...dmis.org>,
Brendan Gregg <bgregg@...flix.com>, netdev@...r.kernel.org,
LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v5 net-next] net/tcp: trace all TCP/IP state transition
with tcp_set_state tracepoint
2017-12-08 4:02 GMT+08:00 Marcelo Ricardo Leitner <marcelo.leitner@...il.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@...il.com>
>> Acked-by: Song Liu <songliubraving@...com>
>> Reviewed-by: Marcelo Ricardo Leitner <marcelo.leitner@...il.com>
>> Signed-off-by: Yafang Shao <laoar.shao@...il.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
>>
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