[PATCH 3/6] tracing: Enable adding dynamic events early stage

[Masami Hiramatsu]

Split the event fields initialization from creating new
event directory.
This allows the boot-time tracing to define dynamic events
before initializing events directory on tracefs.

Signed-off-by: Masami Hiramatsu <mhira...@kernel.org>
---
 kernel/trace/trace_events.c |    9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index a2531301b44f..720b0d72ea52 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -38,6 +38,7 @@ DEFINE_MUTEX(event_mutex);
 LIST_HEAD(ftrace_events);
 static LIST_HEAD(ftrace_generic_fields);
 static LIST_HEAD(ftrace_common_fields);
+static bool eventdir_initialized;
 
 #define GFP_TRACE (GFP_KERNEL | __GFP_ZERO)
 
@@ -2486,7 +2487,10 @@ __trace_add_new_event(struct trace_event_call *call, 
struct trace_array *tr)
        if (!file)
                return -ENOMEM;
 
-       return event_create_dir(tr->event_dir, file);
+       if (eventdir_initialized)
+               return event_create_dir(tr->event_dir, file);
+       else
+               return event_define_fields(call);
 }
 
 /*
@@ -3483,6 +3487,9 @@ __init int event_trace_init(void)
        if (ret)
                pr_warn("Failed to register trace events module notifier\n");
 #endif
+
+       eventdir_initialized = true;
+
        return 0;
 }