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

Steven Rostedt
2017-11-10T00:57:12Z

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