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Commit 2fbb90db authored by Steven Rostedt's avatar Steven Rostedt Committed by Steven Rostedt
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tracing/rcu: Add trace_##name##__rcuidle() static tracepoint for inside rcu_idle_exit() sections 

Added is a new static inline function that lets *any* tracepoint be used
inside a rcu_idle_exit() section. And this also solves the problem where
the same tracepoint may be used inside a rcu_idle_exit() section as well
as outside of one.

I added a new tracepoint function with a "_rcuidle" extension. All
tracepoints can be used with either the normal "trace_foobar()"
function, or the "trace_foobar_rcuidle()" function when inside a
rcu_idle_exit() section.

All tracepoints defined by TRACE_EVENT() or any of the derivatives
will have a "_rcuidle()" function also defined. When a tracepoint is
used within an rcu_idle_exit() section, the "_rcuidle()" version must
be used. This denotes that the tracepoint is within rcu_idle_exit()
and it allows the rcu read locks within the tracepoint to still
be valid, as this version takes us out of rcu_idle_exit().

Another nice aspect about this patch is that "static inline"s are not
compiled into text when not used. So only the tracepoints that actually
use the _rcuidle() version will have them defined in the actual text
that is booted.

Link: http://lkml.kernel.org/r/1328563113.2200.39.camel@gandalf.stny.rr.com

>

Acked-by: default avatarPaul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: default avatarJosh Triplett <josh@joshtriplett.org>
Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
parent f069686e

include/linux/tracepoint.h

+18 −4
Original line number Diff line number Diff line
@@ -114,7 +114,7 @@ static inline void tracepoint_synchronize_unregister(void) 
 * as "(void *, void)". The DECLARE_TRACE_NOARGS() will pass in just

 * "void *data", where as the DECLARE_TRACE() will pass in "void *data, proto".

 */

#define __DO_TRACE(tp, proto, args, cond)				\

#define __DO_TRACE(tp, proto, args, cond, prercu, postrcu)		\

	do {								\

		struct tracepoint_func *it_func_ptr;			\

		void *it_func;						\
@@ -122,6 +122,7 @@ static inline void tracepoint_synchronize_unregister(void) 
									\

		if (!(cond))						\

			return;						\

		prercu;							\

		rcu_read_lock_sched_notrace();				\

		it_func_ptr = rcu_dereference_sched((tp)->funcs);	\

		if (it_func_ptr) {					\
@@ -132,6 +133,7 @@ static inline void tracepoint_synchronize_unregister(void) 
			} while ((++it_func_ptr)->func);		\

		}							\

		rcu_read_unlock_sched_notrace();			\

		postrcu;						\

	} while (0)



/*
@@ -147,7 +149,17 @@ static inline void tracepoint_synchronize_unregister(void) 
			__DO_TRACE(&__tracepoint_##name,		\

				TP_PROTO(data_proto),			\

				TP_ARGS(data_args),			\

				TP_CONDITION(cond));			\

				TP_CONDITION(cond),,);			\

	}								\

	static inline void trace_##name##_rcuidle(proto)		\

	{								\

		if (static_branch(&__tracepoint_##name.key))		\

			__DO_TRACE(&__tracepoint_##name,		\

				TP_PROTO(data_proto),			\

				TP_ARGS(data_args),			\

				TP_CONDITION(cond),			\

				rcu_idle_exit(),			\

				rcu_idle_enter());			\

	}								\

	static inline int						\

	register_trace_##name(void (*probe)(data_proto), void *data)	\
@@ -193,6 +205,8 @@ static inline void tracepoint_synchronize_unregister(void) 
#define __DECLARE_TRACE(name, proto, args, cond, data_proto, data_args) \

	static inline void trace_##name(proto)				\

	{ }								\

	static inline void trace_##name##_rcuidle(proto)		\

	{ }								\

	static inline int						\

	register_trace_##name(void (*probe)(data_proto),		\

			      void *data)				\