tracing/filters: Add __field_ext() to TRACE_EVENT

Add __field_ext(), so a field can be assigned to a specific
filter_type, which matches a corresponding filter function.

For example, a later patch will allow this:
	__field_ext(const char *, str, FILTER_PTR_STR);

Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
LKML-Reference: <4A7B9272.6050709@cn.fujitsu.com>

[
  Fixed a -1 to FILTER_OTHER
  Forward ported to latest kernel.
]

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index 5740e90..d33bcde 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -28,7 +28,8 @@
 LIST_HEAD(ftrace_events);
 
 int trace_define_field(struct ftrace_event_call *call, const char *type,
-		       const char *name, int offset, int size, int is_signed)
+		       const char *name, int offset, int size, int is_signed,
+		       int filter_type)
 {
 	struct ftrace_event_field *field;
 
@@ -44,7 +45,11 @@
 	if (!field->type)
 		goto err;
 
-	field->filter_type = filter_assign_type(type);
+	if (filter_type == FILTER_OTHER)
+		field->filter_type = filter_assign_type(type);
+	else
+		field->filter_type = filter_type;
+
 	field->offset = offset;
 	field->size = size;
 	field->is_signed = is_signed;
@@ -68,7 +73,7 @@
 	ret = trace_define_field(call, #type, "common_" #item,		\
 				 offsetof(typeof(ent), item),		\
 				 sizeof(ent.item),			\
-				 is_signed_type(type));			\
+				 is_signed_type(type), FILTER_OTHER);	\
 	if (ret)							\
 		return ret;