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Commit 5f893b26 authored by Steven Rostedt (Red Hat)'s avatar Steven Rostedt (Red Hat) Committed by Steven Rostedt
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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: default avatarPaul E. McKenney <paulmck@linux.vnet.ibm.com>
Suggested-by: default avatarThomas Gleixner <tglx@linutronix.de>
Tested-by: default avatarThomas Gleixner <tglx@linutronix.de>
Acked-by: default avatarThomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
parent aee4e5f3

include/linux/ftrace.h

+6 −0
Original line number Diff line number Diff line
@@ -39,6 +39,12 @@ 
# define FTRACE_FORCE_LIST_FUNC 0

#endif



/* Main tracing buffer and events set up */

#ifdef CONFIG_TRACING

void trace_init(void);

#else

static inline void trace_init(void) { }

#endif



struct module;

struct ftrace_hash;

init/main.c

+4 −0
Original line number Diff line number Diff line
@@ -577,6 +577,10 @@ asmlinkage __visible void __init start_kernel(void) 
		local_irq_disable();

	idr_init_cache();

	rcu_init();



	/* trace_printk() and trace points may be used after this */

	trace_init();



	context_tracking_init();

	radix_tree_init();

	/* init some links before init_ISA_irqs() */

kernel/trace/trace.c

+7 −1
Original line number Diff line number Diff line
@@ -6876,6 +6876,13 @@ __init static int tracer_alloc_buffers(void) 
	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);

kernel/trace/trace.h

+13 −0
Original line number Diff line number Diff line
@@ -1301,4 +1301,17 @@ int perf_ftrace_event_register(struct ftrace_event_call *call, 
#define perf_ftrace_event_register NULL

#endif



#ifdef CONFIG_FTRACE_SYSCALLS

void init_ftrace_syscalls(void);

#else

static inline void init_ftrace_syscalls(void) { }

#endif



#ifdef CONFIG_EVENT_TRACING

void trace_event_init(void);

#else

static inline void __init trace_event_init(void) { }

#endif





#endif /* _LINUX_KERNEL_TRACE_H */

kernel/trace/trace_events.c

+8 −2
Original line number Diff line number Diff line
@@ -2477,8 +2477,14 @@ static __init int event_trace_init(void) 
#endif

	return 0;

}

early_initcall(event_trace_memsetup);

core_initcall(event_trace_enable);



void __init trace_event_init(void)

{

	event_trace_memsetup();

	init_ftrace_syscalls();

	event_trace_enable();

}



fs_initcall(event_trace_init);



#ifdef CONFIG_FTRACE_STARTUP_TEST