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

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Date:   Thu, 9 Nov 2017 19:57:12 -0500
From:   Steven Rostedt <rostedt@...dmis.org>
To:     David Miller <davem@...emloft.net>
Cc:     Song Liu <songliubraving@...com>,
        Alexei Starovoitov <alexei.starovoitov@...il.com>,
        Yafang Shao <laoar.shao@...il.com>,
        "mingo@...hat.com" <mingo@...hat.com>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: [PATCH] tcp: Export to userspace the TCP state names for the trace
 events


From: "Steven Rostedt (VMware)" <rostedt@...dmis.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@...dmis.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