tracing: add raw fast tracing interface for trace events

This patch adds the interface to enable the C style trace points.
In the directory /debugfs/tracing/events/subsystem/event
We now have three files:

 enable : values 0 or 1 to enable or disable the trace event.

 available_types: values 'raw' and 'printf' which indicate the tracing
       types available for the trace point. If a developer does not
       use the TRACE_EVENT_FORMAT macro and just uses the TRACE_FORMAT
       macro, then only 'printf' will be available. This file is
       read only.

 type: values 'raw' or 'printf'. This indicates which type of tracing
       is active for that trace point. 'printf' is the default and
       if 'raw' is not available, this file is read only.

 # echo raw > /debug/tracing/events/sched/sched_wakeup/type
 # echo 1 > /debug/tracing/events/sched/sched_wakeup/enable

 Will enable the C style tracing for the sched_wakeup trace point.

Signed-off-by: Steven Rostedt <srostedt@redhat.com>

1 files changed, 7 insertions, 0 deletions

diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index aa1ab0cb80ab..f6fa0b9f83a8 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -726,6 +726,12 @@ static inline void trace_branch_disable(void)
 }
 #endif /* CONFIG_BRANCH_TRACER */
 
+/* trace event type bit fields, not numeric */
+enum {
+        TRACE_EVENT_TYPE_PRINTF         = 1,
+        TRACE_EVENT_TYPE_RAW            = 2,
+};
+
 struct ftrace_event_call {
         char            *name;
         char            *system;
@@ -736,6 +742,7 @@ struct ftrace_event_call {
         int             id;
         struct dentry   *raw_dir;
         int             raw_enabled;
+        int             type;
         int             (*raw_init)(void);
         int             (*raw_reg)(void);
         void            (*raw_unreg)(void);