[ltt-dev] [PATCH] Fix tracepoints for network socket

[mathieu.desnoyers@polymtl.ca (Mathieu Desnoyers)]

* Atsushi Tsuji (a-tsuji at bk.jp.nec.com) wrote:
> Hi,
>
> Currently, the tracepoints for network socket could not trace all the
> network activity due to its location, sock_{send/recv}msg, because there
> is the path without through sock_{send/recv}msg (like below).
>
> Kernel path for sendmsg:
>   sys_write      sys_{send/sendto/sendmsg}
>      |                     |
>   sock_aio_write   sock_sendmsg
>        \                  /
>         \                /
>           __sock_sendmsg
>
> So I think __sock_{send/recv}msg is better tracepoints to track
> network socket activity.
>
> And I'd like to request to get the return value on those tracepoints
> to track the real size of sending/recieving by user and the error status
> of __sock_{send/recv}msg.
>
> The below patch is for lttng tree to change those tracepoints.
>

Hi Atsushi,

Thanks for the patch. I modified it a bit to apply on my tree. I also
removed the size argument you added, because it duplicates the
return value recorded by the syscall_exit event. It will be in LTTng for
2.6.29-rc4.

Mathieu

> Signed-off-by: Atsushi Tsuji <a-tsuji at bk.jp.nec.com>
> ---
> diff --git a/ltt/probes/net-trace.c b/ltt/probes/net-trace.c
> index 2c88ec6..34cef1a 100644
> --- a/ltt/probes/net-trace.c
> +++ b/ltt/probes/net-trace.c
> @@ -79,18 +79,18 @@ void probe_socket_sendmsg(struct socket *sock, struct msghdr
> *msg,
>  		size_t size, int ret)
>  {
>  	trace_mark_tp(net, socket_sendmsg, socket_sendmsg, probe_socket_sendmsg,
> -		"sock %p family %d type %d protocol %d size %zu",
> +		"sock %p family %d type %d protocol %d size %zu ret %d",
>  		sock, sock->sk->sk_family, sock->sk->sk_type,
> -		sock->sk->sk_protocol, size);
> +		sock->sk->sk_protocol, size, ret);
>  }
>
>  void probe_socket_recvmsg(struct socket *sock, struct msghdr *msg,
>  		size_t size, int flags, int ret)
>  {
>  	trace_mark_tp(net, socket_recvmsg, socket_recvmsg, probe_socket_recvmsg,
> -		"sock %p family %d type %d protocol %d size %zu",
> +		"sock %p family %d type %d protocol %d size %zu ret %d",
>  		sock, sock->sk->sk_family, sock->sk->sk_type,
> -		sock->sk->sk_protocol, size);
> +		sock->sk->sk_protocol, size, ret);
>  }
>
>  void probe_socket_create(struct socket *sock, int fd)
> diff --git a/net/socket.c b/net/socket.c
> index 2b63bab..e8b2b5d 100644
> --- a/net/socket.c
> +++ b/net/socket.c
> @@ -567,7 +567,11 @@ static inline int __sock_sendmsg(struct kiocb *iocb, struct
> socket *sock,
>  	if (err)
>  		return err;
>
> -	return sock->ops->sendmsg(iocb, sock, msg, size);
> +	err = sock->ops->sendmsg(iocb, sock, msg, size);
> +	trace_socket_sendmsg(sock, msg, size, err);
> +
> +	return err;
> +
>  }
>
>  int sock_sendmsg(struct socket *sock, struct msghdr *msg, size_t size)
> @@ -581,7 +585,6 @@ int sock_sendmsg(struct socket *sock, struct msghdr *msg,
> size_t size)
>  	ret = __sock_sendmsg(&iocb, sock, msg, size);
>  	if (-EIOCBQUEUED == ret)
>  		ret = wait_on_sync_kiocb(&iocb);
> -	trace_socket_sendmsg(sock, msg, size, ret);
>  	return ret;
>  }
>
> @@ -650,7 +653,11 @@ static inline int __sock_recvmsg(struct kiocb *iocb, struct
> socket *sock,
>  	if (err)
>  		return err;
>
> -	return sock->ops->recvmsg(iocb, sock, msg, size, flags);
> +	err = sock->ops->recvmsg(iocb, sock, msg, size, flags);
> +	trace_socket_recvmsg(sock, msg, size, flags, err);
> +
> +	return err;
> +
>  }
>
>  int sock_recvmsg(struct socket *sock, struct msghdr *msg,
> @@ -666,7 +673,6 @@ int sock_recvmsg(struct socket *sock, struct msghdr *msg,
>  	ret = __sock_recvmsg(&iocb, sock, msg, size, flags);
>  	if (-EIOCBQUEUED == ret)
>  		ret = wait_on_sync_kiocb(&iocb);
> -	trace_socket_recvmsg(sock, msg, size, flags, ret);
>  	return ret;
>  }
>
>
>
>

-- 
Mathieu Desnoyers
OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F  BA06 3F25 A8FE 3BAE 9A68