[for-next][PATCH 23/26] tracing: Enable adding dynamic events early stage

Steven Rostedt
2020-09-22T01:24:57Z

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.

Link: https://lkml.kernel.org/r/159974153790.478751.3475515065034825374.stgit@devnote2

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.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 8e87fbab6930..42c0e7df6e70 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);
}

/*
@@ -3478,6 +3482,9 @@ __init int event_trace_init(void)
if (ret)
pr_warn("Failed to register trace events module notifier\n");
#endif
+
+ eventdir_initialized = true;
+
return 0;
}

--
2.28.0