tracing/events: Add trace_define_common_fields()

Extract duplicate code. Also prepare for the later patch.

Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Cc: Jason Baron <jbaron@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <4A8BAFB8.1010304@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/include/linux/ftrace_event.h b/include/linux/ftrace_event.h
index 35b3a4a..427cbae 100644
--- a/include/linux/ftrace_event.h
+++ b/include/linux/ftrace_event.h
@@ -142,6 +142,7 @@
 
 extern int trace_define_field(struct ftrace_event_call *call, char *type,
 			      char *name, int offset, int size, int is_signed);
+extern int trace_define_common_fields(struct ftrace_event_call *call);
 
 #define is_signed_type(type)	(((type)(-1)) < 0)
 
@@ -166,11 +167,4 @@
 		__trace_printk(ip, fmt, ##args);			\
 } while (0)
 
-#define __common_field(type, item, is_signed)				\
-	ret = trace_define_field(event_call, #type, "common_" #item,	\
-				 offsetof(typeof(field.ent), item),	\
-				 sizeof(field.ent.item), is_signed);	\
-	if (ret)							\
-		return ret;
-
 #endif /* _LINUX_FTRACE_EVENT_H */
diff --git a/include/trace/ftrace.h b/include/trace/ftrace.h
index 4e81c9b..1274002 100644
--- a/include/trace/ftrace.h
+++ b/include/trace/ftrace.h
@@ -299,11 +299,9 @@
 	struct ftrace_raw_##call field;					\
 	int ret;							\
 									\
-	__common_field(int, type, 1);					\
-	__common_field(unsigned char, flags, 0);			\
-	__common_field(unsigned char, preempt_count, 0);		\
-	__common_field(int, pid, 1);					\
-	__common_field(int, tgid, 1);					\
+	ret = trace_define_common_fields(event_call);			\
+	if (ret)							\
+		return ret;						\
 									\
 	tstruct;							\
 									\