Re: [PATCH] tcp: Export to userspace the TCP state names for the trace events

Song Liu
2017-11-10T01:42:32Z

> On Nov 9, 2017, at 4:57 PM, Steven Rostedt <rostedt@goodmis.org> wrote:
>
>
> From: "Steven Rostedt (VMware)" <rostedt@goodmis.org>
>
> The TCP trace events (specifically tcp_set_state), maps emums to symbol
> names via __print_symbolic(). But this only works for reading trace events
> from the tracefs trace files. If perf or trace-cmd were to record these
> events, the event format file does not convert the enum names into numbers,
> and you get something like:
>
> __print_symbolic(REC->oldstate,
> { TCP_ESTABLISHED, "TCP_ESTABLISHED" },
> { TCP_SYN_SENT, "TCP_SYN_SENT" },
> { TCP_SYN_RECV, "TCP_SYN_RECV" },
> { TCP_FIN_WAIT1, "TCP_FIN_WAIT1" },
> { TCP_FIN_WAIT2, "TCP_FIN_WAIT2" },
> { TCP_TIME_WAIT, "TCP_TIME_WAIT" },
> { TCP_CLOSE, "TCP_CLOSE" },
> { TCP_CLOSE_WAIT, "TCP_CLOSE_WAIT" },
> { TCP_LAST_ACK, "TCP_LAST_ACK" },
> { TCP_LISTEN, "TCP_LISTEN" },
> { TCP_CLOSING, "TCP_CLOSING" },
> { TCP_NEW_SYN_RECV, "TCP_NEW_SYN_RECV" })
>
> Where trace-cmd and perf do not know the values of those enums.
>
> Use the TRACE_DEFINE_ENUM() macros that will have the trace events convert
> the enum strings into their values at system boot. This will allow perf and
> trace-cmd to see actual numbers and not enums:
>
> __print_symbolic(REC->oldstate,
> { 1, "TCP_ESTABLISHED" },
> { 2, "TCP_SYN_SENT" },
> { 3, "TCP_SYN_RECV" },
> { 4, "TCP_FIN_WAIT1" },
> { 5, "TCP_FIN_WAIT2" },
> { 6, "TCP_TIME_WAIT" },
> { 7, "TCP_CLOSE" },
> { 8, "TCP_CLOSE_WAIT" },
> { 9, "TCP_LAST_ACK" },
> { 10, "TCP_LISTEN" },
> { 11, "TCP_CLOSING" },
> { 12, "TCP_NEW_SYN_RECV" })
>
> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
> ---
> include/trace/events/tcp.h | 41 ++++++++++++++++++++++++++++-------------
> 1 file changed, 28 insertions(+), 13 deletions(-)
>
> diff --git a/include/trace/events/tcp.h b/include/trace/events/tcp.h
> index 07cccca6cbf1..62e5bad7901f 100644
> --- a/include/trace/events/tcp.h
> +++ b/include/trace/events/tcp.h
> @@ -9,21 +9,36 @@
> #include <linux/tracepoint.h>
> #include <net/ipv6.h>
>
> +#define tcp_state_names \
> + EM(TCP_ESTABLISHED) \
> + EM(TCP_SYN_SENT) \
> + EM(TCP_SYN_RECV) \
> + EM(TCP_FIN_WAIT1) \
> + EM(TCP_FIN_WAIT2) \
> + EM(TCP_TIME_WAIT) \
> + EM(TCP_CLOSE) \
> + EM(TCP_CLOSE_WAIT) \
> + EM(TCP_LAST_ACK) \
> + EM(TCP_LISTEN) \
> + EM(TCP_CLOSING) \
> + EMe(TCP_NEW_SYN_RECV)
> +
> +/* enums need to be exported to user space */
> +#undef EM
> +#undef EMe
> +#define EM(a) TRACE_DEFINE_ENUM(a);
> +#define EMe(a) TRACE_DEFINE_ENUM(a);
> +
> +tcp_state_names
> +
> +#undef EM
> +#undef EMe
> +#define EM(a) tcp_state_name(a),
> +#define EMe(a) tcp_state_name(a)
> +
> #define tcp_state_name(state) { state, #state }
> #define show_tcp_state_name(val) \
> - __print_symbolic(val, \
> - tcp_state_name(TCP_ESTABLISHED), \
> - tcp_state_name(TCP_SYN_SENT), \
> - tcp_state_name(TCP_SYN_RECV), \
> - tcp_state_name(TCP_FIN_WAIT1), \
> - tcp_state_name(TCP_FIN_WAIT2), \
> - tcp_state_name(TCP_TIME_WAIT), \
> - tcp_state_name(TCP_CLOSE), \
> - tcp_state_name(TCP_CLOSE_WAIT), \
> - tcp_state_name(TCP_LAST_ACK), \
> - tcp_state_name(TCP_LISTEN), \
> - tcp_state_name(TCP_CLOSING), \
> - tcp_state_name(TCP_NEW_SYN_RECV))
> + __print_symbolic(val, tcp_state_names)
>
> /*
> * tcp event with arguments sk and skb
> --
> 2.13.6
>

Reviewed-and-tested-by: Song Liu <songliubraving@fb.com>