tracing: Move enabling tracepoints to just after rcu_init()

Enabling tracepoints at boot up can be very useful. The tracepoint
can be initialized right after RCU has been. There's no need to
wait for the early_initcall() to be called. That's too late for some
things that can use tracepoints for debugging. Move the logic to
enable tracepoints out of the initcalls and into init/main.c to
right after rcu_init().

This also allows trace_printk() to be used early too.

Link: http://lkml.kernel.org/r/alpine.DEB.2.11.1412121539300.16494@nanos
Link: http://lkml.kernel.org/r/20141214164104.307127356@goodmis.org

Reviewed-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

1 files changed, 7 insertions, 1 deletions

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 4ceb254..ec3ca69 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -6876,6 +6876,13 @@ out:
 	return ret;
 }
 
+void __init trace_init(void)
+{
+	tracer_alloc_buffers();
+	init_ftrace_syscalls();
+	trace_event_init();	
+}
+
 __init static int clear_boot_tracer(void)
 {
 	/*
@@ -6895,6 +6902,5 @@ __init static int clear_boot_tracer(void)
 	return 0;
 }
 
-early_initcall(tracer_alloc_buffers);
 fs_initcall(tracer_init_debugfs);
 late_initcall(clear_boot_tracer);