tracing: add __print_symbolic to trace events

This patch adds __print_symbolic which is similar to __print_flags but
works for an enumeration type instead. That is, there is only a one to one
mapping between the values and the symbols. When a match is made, then
it is printed, otherwise the hex value is outputed.

[ Impact: add interface for showing symbol names in events ]

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
diff --git a/include/trace/ftrace.h b/include/trace/ftrace.h
index 22c9471..87fc227 100644
--- a/include/trace/ftrace.h
+++ b/include/trace/ftrace.h
@@ -130,6 +130,14 @@
 		ftrace_print_flags_seq(p, delim, flag, flags);		\
 	})
 
+#undef __print_symbolic
+#define __print_symbolic(value, symbol_array...)			\
+	({								\
+		static const struct trace_print_flags symbols[] =	\
+			{ symbol_array, { -1, NULL }};			\
+		ftrace_print_symbols_seq(p, value, symbols);		\
+	})
+
 #undef TRACE_EVENT
 #define TRACE_EVENT(call, proto, args, tstruct, assign, print)		\
 enum print_line_t							\