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

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) <[e-mail]>
Acked-by: Song Liu <[e-mail]>
Signed-off-by: Yafang Shao <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

include/trace/events/tcp.h

···
 #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