[net-next-2.6.git] / include / linux / tracepoint.h

#ifndef _LINUX_TRACEPOINT_H
#define _LINUX_TRACEPOINT_H

/*
 * Kernel Tracepoint API.
 *
 * See Documentation/trace/tracepoints.txt.
 *
 * (C) Copyright 2008 Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
 *
 * Heavily inspired from the Linux Kernel Markers.
 *
 * This file is released under the GPLv2.
 * See the file COPYING for more details.
 */

#include <linux/types.h>
#include <linux/rcupdate.h>

struct module;
struct tracepoint;

struct tracepoint_func {
	void *func;
	void *data;
};

struct tracepoint {
	const char *name;		/* Tracepoint name */
	int state;			/* State. */
	void (*regfunc)(void);
	void (*unregfunc)(void);
	struct tracepoint_func *funcs;
} __attribute__((aligned(32)));		/*
					 * Aligned on 32 bytes because it is
					 * globally visible and gcc happily
					 * align these on the structure size.
					 * Keep in sync with vmlinux.lds.h.
					 */

/*
 * Connect a probe to a tracepoint.
 * Internal API, should not be used directly.
 */
extern int tracepoint_probe_register(const char *name, void *probe, void *data);

/*
 * Disconnect a probe from a tracepoint.
 * Internal API, should not be used directly.
 */
extern int
tracepoint_probe_unregister(const char *name, void *probe, void *data);

extern int tracepoint_probe_register_noupdate(const char *name, void *probe,
					      void *data);
extern int tracepoint_probe_unregister_noupdate(const char *name, void *probe,
						void *data);
extern void tracepoint_probe_update_all(void);

struct tracepoint_iter {
	struct module *module;
	struct tracepoint *tracepoint;
};

extern void tracepoint_iter_start(struct tracepoint_iter *iter);
extern void tracepoint_iter_next(struct tracepoint_iter *iter);
extern void tracepoint_iter_stop(struct tracepoint_iter *iter);
extern void tracepoint_iter_reset(struct tracepoint_iter *iter);
extern int tracepoint_get_iter_range(struct tracepoint **tracepoint,
	struct tracepoint *begin, struct tracepoint *end);

/*
 * tracepoint_synchronize_unregister must be called between the last tracepoint
 * probe unregistration and the end of module exit to make sure there is no
 * caller executing a probe when it is freed.
 */
static inline void tracepoint_synchronize_unregister(void)
{
	synchronize_sched();
}

#define PARAMS(args...) args

#ifdef CONFIG_TRACEPOINTS
extern void tracepoint_update_probe_range(struct tracepoint *begin,
	struct tracepoint *end);
#else
static inline void tracepoint_update_probe_range(struct tracepoint *begin,
	struct tracepoint *end)
{ }
#endif /* CONFIG_TRACEPOINTS */

#endif /* _LINUX_TRACEPOINT_H */

/*
 * Note: we keep the TRACE_EVENT and DECLARE_TRACE outside the include
 *  file ifdef protection.
 *  This is due to the way trace events work. If a file includes two
 *  trace event headers under one "CREATE_TRACE_POINTS" the first include
 *  will override the TRACE_EVENT and break the second include.
 */

#ifndef DECLARE_TRACE

#define TP_PROTO(args...)	args
#define TP_ARGS(args...)	args

#ifdef CONFIG_TRACEPOINTS

/*
 * it_func[0] is never NULL because there is at least one element in the array
 * when the array itself is non NULL.
 *
 * Note, the proto and args passed in includes "__data" as the first parameter.
 * The reason for this is to handle the "void" prototype. If a tracepoint
 * has a "void" prototype, then it is invalid to declare a function
 * 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)					\
	do {								\
		struct tracepoint_func *it_func_ptr;			\
		void *it_func;						\
		void *__data;						\
									\
		rcu_read_lock_sched_notrace();				\
		it_func_ptr = rcu_dereference_sched((tp)->funcs);	\
		if (it_func_ptr) {					\
			do {						\
				it_func = (it_func_ptr)->func;		\
				__data = (it_func_ptr)->data;		\
				((void(*)(proto))(it_func))(args);	\
			} while ((++it_func_ptr)->func);		\
		}							\
		rcu_read_unlock_sched_notrace();			\
	} while (0)

/*
 * Make sure the alignment of the structure in the __tracepoints section will
 * not add unwanted padding between the beginning of the section and the
 * structure. Force alignment to the same alignment as the section start.
 */
#define __DECLARE_TRACE(name, proto, args, data_proto, data_args)	\
	extern struct tracepoint __tracepoint_##name;			\
	static inline void trace_##name(proto)				\
	{								\
		if (unlikely(__tracepoint_##name.state))		\
			__DO_TRACE(&__tracepoint_##name,		\
				TP_PROTO(data_proto),			\
				TP_ARGS(data_args));			\
	}								\
	static inline int						\
	register_trace_##name(void (*probe)(data_proto), void *data)	\
	{								\
		return tracepoint_probe_register(#name, (void *)probe,	\
						 data);			\
	}								\
	static inline int						\
	unregister_trace_##name(void (*probe)(data_proto), void *data)	\
	{								\
		return tracepoint_probe_unregister(#name, (void *)probe, \
						   data);		\
	}								\
	static inline void						\
	check_trace_callback_type_##name(void (*cb)(data_proto))	\
	{								\
	}

#define DEFINE_TRACE_FN(name, reg, unreg)				\
	static const char __tpstrtab_##name[]				\
	__attribute__((section("__tracepoints_strings"))) = #name;	\
	struct tracepoint __tracepoint_##name				\
	__attribute__((section("__tracepoints"), aligned(32))) =	\
		{ __tpstrtab_##name, 0, reg, unreg, NULL }

#define DEFINE_TRACE(name)						\
	DEFINE_TRACE_FN(name, NULL, NULL);

#define EXPORT_TRACEPOINT_SYMBOL_GPL(name)				\
	EXPORT_SYMBOL_GPL(__tracepoint_##name)
#define EXPORT_TRACEPOINT_SYMBOL(name)					\
	EXPORT_SYMBOL(__tracepoint_##name)

#else /* !CONFIG_TRACEPOINTS */
#define __DECLARE_TRACE(name, proto, args, data_proto, data_args)	\
	static inline void trace_##name(proto)				\
	{ }								\
	static inline int						\
	register_trace_##name(void (*probe)(data_proto),		\
			      void *data)				\
	{								\
		return -ENOSYS;						\
	}								\
	static inline int						\
	unregister_trace_##name(void (*probe)(data_proto),		\
				void *data)				\
	{								\
		return -ENOSYS;						\
	}								\
	static inline void check_trace_callback_type_##name(void (*cb)(data_proto)) \
	{								\
	}

#define DEFINE_TRACE_FN(name, reg, unreg)
#define DEFINE_TRACE(name)
#define EXPORT_TRACEPOINT_SYMBOL_GPL(name)
#define EXPORT_TRACEPOINT_SYMBOL(name)

#endif /* CONFIG_TRACEPOINTS */

/*
 * The need for the DECLARE_TRACE_NOARGS() is to handle the prototype
 * (void). "void" is a special value in a function prototype and can
 * not be combined with other arguments. Since the DECLARE_TRACE()
 * macro adds a data element at the beginning of the prototype,
 * we need a way to differentiate "(void *data, proto)" from
 * "(void *data, void)". The second prototype is invalid.
 *
 * DECLARE_TRACE_NOARGS() passes "void" as the tracepoint prototype
 * and "void *__data" as the callback prototype.
 *
 * DECLARE_TRACE() passes "proto" as the tracepoint protoype and
 * "void *__data, proto" as the callback prototype.
 */
#define DECLARE_TRACE_NOARGS(name)					\
		__DECLARE_TRACE(name, void, , void *__data, __data)

#define DECLARE_TRACE(name, proto, args)				\
		__DECLARE_TRACE(name, PARAMS(proto), PARAMS(args),	\
				PARAMS(void *__data, proto),		\
				PARAMS(__data, args))

#endif /* DECLARE_TRACE */

#ifndef TRACE_EVENT
/*
 * For use with the TRACE_EVENT macro:
 *
 * We define a tracepoint, its arguments, its printk format
 * and its 'fast binay record' layout.
 *
 * Firstly, name your tracepoint via TRACE_EVENT(name : the
 * 'subsystem_event' notation is fine.
 *
 * Think about this whole construct as the
 * 'trace_sched_switch() function' from now on.
 *
 *
 *  TRACE_EVENT(sched_switch,
 *
 *	*
 *	* A function has a regular function arguments
 *	* prototype, declare it via TP_PROTO():
 *	*
 *
 *	TP_PROTO(struct rq *rq, struct task_struct *prev,
 *		 struct task_struct *next),
 *
 *	*
 *	* Define the call signature of the 'function'.
 *	* (Design sidenote: we use this instead of a
 *	*  TP_PROTO1/TP_PROTO2/TP_PROTO3 ugliness.)
 *	*
 *
 *	TP_ARGS(rq, prev, next),
 *
 *	*
 *	* Fast binary tracing: define the trace record via
 *	* TP_STRUCT__entry(). You can think about it like a
 *	* regular C structure local variable definition.
 *	*
 *	* This is how the trace record is structured and will
 *	* be saved into the ring buffer. These are the fields
 *	* that will be exposed to user-space in
 *	* /sys/kernel/debug/tracing/events/<*>/format.
 *	*
 *	* The declared 'local variable' is called '__entry'
 *	*
 *	* __field(pid_t, prev_prid) is equivalent to a standard declariton:
 *	*
 *	*	pid_t	prev_pid;
 *	*
 *	* __array(char, prev_comm, TASK_COMM_LEN) is equivalent to:
 *	*
 *	*	char	prev_comm[TASK_COMM_LEN];
 *	*
 *
 *	TP_STRUCT__entry(
 *		__array(	char,	prev_comm,	TASK_COMM_LEN	)
 *		__field(	pid_t,	prev_pid			)
 *		__field(	int,	prev_prio			)
 *		__array(	char,	next_comm,	TASK_COMM_LEN	)
 *		__field(	pid_t,	next_pid			)
 *		__field(	int,	next_prio			)
 *	),
 *
 *	*
 *	* Assign the entry into the trace record, by embedding
 *	* a full C statement block into TP_fast_assign(). You
 *	* can refer to the trace record as '__entry' -
 *	* otherwise you can put arbitrary C code in here.
 *	*
 *	* Note: this C code will execute every time a trace event
 *	* happens, on an active tracepoint.
 *	*
 *
 *	TP_fast_assign(
 *		memcpy(__entry->next_comm, next->comm, TASK_COMM_LEN);
 *		__entry->prev_pid	= prev->pid;
 *		__entry->prev_prio	= prev->prio;
 *		memcpy(__entry->prev_comm, prev->comm, TASK_COMM_LEN);
 *		__entry->next_pid	= next->pid;
 *		__entry->next_prio	= next->prio;
 *	)
 *
 *	*
 *	* Formatted output of a trace record via TP_printk().
 *	* This is how the tracepoint will appear under ftrace
 *	* plugins that make use of this tracepoint.
 *	*
 *	* (raw-binary tracing wont actually perform this step.)
 *	*
 *
 *	TP_printk("task %s:%d [%d] ==> %s:%d [%d]",
 *		__entry->prev_comm, __entry->prev_pid, __entry->prev_prio,
 *		__entry->next_comm, __entry->next_pid, __entry->next_prio),
 *
 * );
 *
 * This macro construct is thus used for the regular printk format
 * tracing setup, it is used to construct a function pointer based
 * tracepoint callback (this is used by programmatic plugins and
 * can also by used by generic instrumentation like SystemTap), and
 * it is also used to expose a structured trace record in
 * /sys/kernel/debug/tracing/events/.
 *
 * A set of (un)registration functions can be passed to the variant
 * TRACE_EVENT_FN to perform any (un)registration work.
 */

#define DECLARE_EVENT_CLASS(name, proto, args, tstruct, assign, print)
#define DEFINE_EVENT(template, name, proto, args)		\
	DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
#define DEFINE_EVENT_PRINT(template, name, proto, args, print)	\
	DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))

#define TRACE_EVENT(name, proto, args, struct, assign, print)	\
	DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
#define TRACE_EVENT_FN(name, proto, args, struct,		\
		assign, print, reg, unreg)			\
	DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))

#endif /* ifdef TRACE_EVENT (see note above) */
Commit	Line	Data
97e1c18e MD	1	#ifndef _LINUX_TRACEPOINT_H
	2	#define _LINUX_TRACEPOINT_H
	3
	4	/*
	5	* Kernel Tracepoint API.
	6	*
8cd09a59	7	* See Documentation/trace/tracepoints.txt.
97e1c18e MD	8	*
	9	* (C) Copyright 2008 Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
	10	*
	11	* Heavily inspired from the Linux Kernel Markers.
	12	*
	13	* This file is released under the GPLv2.
	14	* See the file COPYING for more details.
	15	*/
	16
	17	#include <linux/types.h>
	18	#include <linux/rcupdate.h>
	19
	20	struct module;
	21	struct tracepoint;
	22
38516ab5 SR	23	struct tracepoint_func {
	24	void *func;
	25	void *data;
	26	};
	27
97e1c18e MD	28	struct tracepoint {
	29	const char name; / Tracepoint name */
	30	int state; /* State. */
97419875 JS	31	void (*regfunc)(void);
97419875 JS	32	void (*unregfunc)(void);
38516ab5	33	struct tracepoint_func *funcs;
7e066fb8 MD	34	} __attribute__((aligned(32))); /*
	35	* Aligned on 32 bytes because it is
	36	* globally visible and gcc happily
	37	* align these on the structure size.
	38	* Keep in sync with vmlinux.lds.h.
	39	*/
97e1c18e	40
2e26ca71 SR	41	/*
	42	* Connect a probe to a tracepoint.
	43	* Internal API, should not be used directly.
	44	*/
38516ab5	45	extern int tracepoint_probe_register(const char name, void probe, void *data);
2e26ca71 SR	46
	47	/*
	48	* Disconnect a probe from a tracepoint.
	49	* Internal API, should not be used directly.
	50	*/
38516ab5 SR	51	extern int
38516ab5 SR	52	tracepoint_probe_unregister(const char name, void probe, void *data);
2e26ca71	53
38516ab5 SR	54	extern int tracepoint_probe_register_noupdate(const char name, void probe,
	55	void *data);
	56	extern int tracepoint_probe_unregister_noupdate(const char name, void probe,
	57	void *data);
2e26ca71 SR	58	extern void tracepoint_probe_update_all(void);
	59
	60	struct tracepoint_iter {
	61	struct module *module;
	62	struct tracepoint *tracepoint;
	63	};
	64
	65	extern void tracepoint_iter_start(struct tracepoint_iter *iter);
	66	extern void tracepoint_iter_next(struct tracepoint_iter *iter);
	67	extern void tracepoint_iter_stop(struct tracepoint_iter *iter);
	68	extern void tracepoint_iter_reset(struct tracepoint_iter *iter);
	69	extern int tracepoint_get_iter_range(struct tracepoint **tracepoint,
	70	struct tracepoint begin, struct tracepoint end);
	71
	72	/*
	73	* tracepoint_synchronize_unregister must be called between the last tracepoint
	74	* probe unregistration and the end of module exit to make sure there is no
	75	* caller executing a probe when it is freed.
	76	*/
	77	static inline void tracepoint_synchronize_unregister(void)
	78	{
	79	synchronize_sched();
	80	}
	81
	82	#define PARAMS(args...) args
	83
	84	#ifdef CONFIG_TRACEPOINTS
	85	extern void tracepoint_update_probe_range(struct tracepoint *begin,
	86	struct tracepoint *end);
	87	#else
	88	static inline void tracepoint_update_probe_range(struct tracepoint *begin,
	89	struct tracepoint *end)
	90	{ }
	91	#endif /* CONFIG_TRACEPOINTS */
	92
	93	#endif /* _LINUX_TRACEPOINT_H */
	94
	95	/*
	96	* Note: we keep the TRACE_EVENT and DECLARE_TRACE outside the include
	97	* file ifdef protection.
	98	* This is due to the way trace events work. If a file includes two
	99	* trace event headers under one "CREATE_TRACE_POINTS" the first include
	100	* will override the TRACE_EVENT and break the second include.
	101	*/
	102
ea20d929 SR	103	#ifndef DECLARE_TRACE
ea20d929 SR	104
2939b046	105	#define TP_PROTO(args...) args
8cd09a59	106	#define TP_ARGS(args...) args
97e1c18e MD	107
	108	#ifdef CONFIG_TRACEPOINTS
	109
	110	/*
	111	* it_func[0] is never NULL because there is at least one element in the array
	112	* when the array itself is non NULL.
38516ab5 SR	113	*
	114	* Note, the proto and args passed in includes "__data" as the first parameter.
	115	* The reason for this is to handle the "void" prototype. If a tracepoint
	116	* has a "void" prototype, then it is invalid to declare a function
	117	* as "(void *, void)". The DECLARE_TRACE_NOARGS() will pass in just
	118	* "void data", where as the DECLARE_TRACE() will pass in "void data, proto".
97e1c18e MD	119	*/
	120	#define __DO_TRACE(tp, proto, args) \
	121	do { \
38516ab5 SR	122	struct tracepoint_func *it_func_ptr; \
	123	void *it_func; \
	124	void *__data; \
97e1c18e	125	\
da7b3eab	126	rcu_read_lock_sched_notrace(); \
38516ab5 SR	127	it_func_ptr = rcu_dereference_sched((tp)->funcs); \
38516ab5 SR	128	if (it_func_ptr) { \
97e1c18e	129	do { \
38516ab5 SR	130	it_func = (it_func_ptr)->func; \
	131	__data = (it_func_ptr)->data; \
	132	((void(*)(proto))(it_func))(args); \
	133	} while ((++it_func_ptr)->func); \
97e1c18e	134	} \
da7b3eab	135	rcu_read_unlock_sched_notrace(); \
97e1c18e MD	136	} while (0)
	137
	138	/*
	139	* Make sure the alignment of the structure in the __tracepoints section will
	140	* not add unwanted padding between the beginning of the section and the
	141	* structure. Force alignment to the same alignment as the section start.
	142	*/
38516ab5	143	#define __DECLARE_TRACE(name, proto, args, data_proto, data_args) \
7e066fb8	144	extern struct tracepoint __tracepoint_##name; \
97e1c18e MD	145	static inline void trace_##name(proto) \
97e1c18e MD	146	{ \
97e1c18e MD	147	if (unlikely(__tracepoint_##name.state)) \
97e1c18e MD	148	__DO_TRACE(&__tracepoint_##name, \
38516ab5 SR	149	TP_PROTO(data_proto), \
38516ab5 SR	150	TP_ARGS(data_args)); \
97e1c18e	151	} \
38516ab5 SR	152	static inline int \
38516ab5 SR	153	register_trace_##name(void (probe)(data_proto), void data) \
97e1c18e	154	{ \
38516ab5 SR	155	return tracepoint_probe_register(#name, (void *)probe, \
38516ab5 SR	156	data); \
97e1c18e	157	} \
38516ab5 SR	158	static inline int \
38516ab5 SR	159	unregister_trace_##name(void (probe)(data_proto), void data) \
97e1c18e	160	{ \
38516ab5 SR	161	return tracepoint_probe_unregister(#name, (void *)probe, \
38516ab5 SR	162	data); \
53da59aa	163	} \
38516ab5 SR	164	static inline void \
38516ab5 SR	165	check_trace_callback_type_##name(void (*cb)(data_proto)) \
53da59aa	166	{ \
97e1c18e MD	167	}
97e1c18e MD	168
97419875	169	#define DEFINE_TRACE_FN(name, reg, unreg) \
7e066fb8 MD	170	static const char __tpstrtab_##name[] \
	171	__attribute__((section("__tracepoints_strings"))) = #name; \
	172	struct tracepoint __tracepoint_##name \
	173	__attribute__((section("__tracepoints"), aligned(32))) = \
97419875 JS	174	{ __tpstrtab_##name, 0, reg, unreg, NULL }
	175
	176	#define DEFINE_TRACE(name) \
	177	DEFINE_TRACE_FN(name, NULL, NULL);
7e066fb8 MD	178
	179	#define EXPORT_TRACEPOINT_SYMBOL_GPL(name) \
	180	EXPORT_SYMBOL_GPL(__tracepoint_##name)
	181	#define EXPORT_TRACEPOINT_SYMBOL(name) \
	182	EXPORT_SYMBOL(__tracepoint_##name)
	183
97e1c18e	184	#else /* !CONFIG_TRACEPOINTS */
38516ab5	185	#define __DECLARE_TRACE(name, proto, args, data_proto, data_args) \
97e1c18e MD	186	static inline void trace_##name(proto) \
97e1c18e MD	187	{ } \
38516ab5 SR	188	static inline int \
	189	register_trace_##name(void (*probe)(data_proto), \
	190	void *data) \
97e1c18e MD	191	{ \
	192	return -ENOSYS; \
	193	} \
38516ab5 SR	194	static inline int \
	195	unregister_trace_##name(void (*probe)(data_proto), \
	196	void *data) \
c420970e MD	197	{ \
c420970e MD	198	return -ENOSYS; \
53da59aa	199	} \
38516ab5	200	static inline void check_trace_callback_type_##name(void (*cb)(data_proto)) \
53da59aa	201	{ \
c420970e	202	}
97e1c18e	203
97419875	204	#define DEFINE_TRACE_FN(name, reg, unreg)
7e066fb8 MD	205	#define DEFINE_TRACE(name)
	206	#define EXPORT_TRACEPOINT_SYMBOL_GPL(name)
	207	#define EXPORT_TRACEPOINT_SYMBOL(name)
	208
97e1c18e	209	#endif /* CONFIG_TRACEPOINTS */
38516ab5 SR	210
	211	/*
	212	* The need for the DECLARE_TRACE_NOARGS() is to handle the prototype
	213	* (void). "void" is a special value in a function prototype and can
	214	* not be combined with other arguments. Since the DECLARE_TRACE()
	215	* macro adds a data element at the beginning of the prototype,
	216	* we need a way to differentiate "(void *data, proto)" from
	217	* "(void *data, void)". The second prototype is invalid.
	218	*
	219	* DECLARE_TRACE_NOARGS() passes "void" as the tracepoint prototype
	220	* and "void *__data" as the callback prototype.
	221	*
	222	* DECLARE_TRACE() passes "proto" as the tracepoint protoype and
	223	* "void *__data, proto" as the callback prototype.
	224	*/
	225	#define DECLARE_TRACE_NOARGS(name) \
	226	__DECLARE_TRACE(name, void, , void *__data, __data)
	227
	228	#define DECLARE_TRACE(name, proto, args) \
	229	__DECLARE_TRACE(name, PARAMS(proto), PARAMS(args), \
	230	PARAMS(void *__data, proto), \
	231	PARAMS(__data, args))
	232
ea20d929	233	#endif /* DECLARE_TRACE */
97e1c18e	234
ea20d929	235	#ifndef TRACE_EVENT
823f9124 SR	236	/*
	237	* For use with the TRACE_EVENT macro:
	238	*
	239	* We define a tracepoint, its arguments, its printk format
	240	* and its 'fast binay record' layout.
	241	*
	242	* Firstly, name your tracepoint via TRACE_EVENT(name : the
	243	* 'subsystem_event' notation is fine.
	244	*
	245	* Think about this whole construct as the
	246	* 'trace_sched_switch() function' from now on.
	247	*
	248	*
	249	* TRACE_EVENT(sched_switch,
	250	*
	251	* *
	252	* * A function has a regular function arguments
	253	* * prototype, declare it via TP_PROTO():
	254	* *
	255	*
ef18012b SR	256	* TP_PROTO(struct rq rq, struct task_struct prev,
ef18012b SR	257	* struct task_struct *next),
823f9124 SR	258	*
	259	* *
	260	* * Define the call signature of the 'function'.
	261	* * (Design sidenote: we use this instead of a
	262	* * TP_PROTO1/TP_PROTO2/TP_PROTO3 ugliness.)
	263	* *
	264	*
ef18012b	265	* TP_ARGS(rq, prev, next),
823f9124 SR	266	*
	267	* *
	268	* * Fast binary tracing: define the trace record via
	269	* * TP_STRUCT__entry(). You can think about it like a
	270	* * regular C structure local variable definition.
	271	* *
	272	* * This is how the trace record is structured and will
	273	* * be saved into the ring buffer. These are the fields
	274	* * that will be exposed to user-space in
156f5a78	275	* * /sys/kernel/debug/tracing/events/<*>/format.
823f9124 SR	276	* *
	277	* * The declared 'local variable' is called '__entry'
	278	* *
	279	* * __field(pid_t, prev_prid) is equivalent to a standard declariton:
	280	* *
	281	* * pid_t prev_pid;
	282	* *
	283	* * __array(char, prev_comm, TASK_COMM_LEN) is equivalent to:
	284	* *
	285	* * char prev_comm[TASK_COMM_LEN];
	286	* *
	287	*
	288	* TP_STRUCT__entry(
	289	* __array( char, prev_comm, TASK_COMM_LEN )
	290	* __field( pid_t, prev_pid )
	291	* __field( int, prev_prio )
	292	* __array( char, next_comm, TASK_COMM_LEN )
	293	* __field( pid_t, next_pid )
	294	* __field( int, next_prio )
	295	* ),
	296	*
	297	* *
	298	* * Assign the entry into the trace record, by embedding
	299	* * a full C statement block into TP_fast_assign(). You
	300	* * can refer to the trace record as '__entry' -
	301	* * otherwise you can put arbitrary C code in here.
	302	* *
	303	* * Note: this C code will execute every time a trace event
	304	* * happens, on an active tracepoint.
	305	* *
	306	*
ef18012b SR	307	* TP_fast_assign(
	308	* memcpy(__entry->next_comm, next->comm, TASK_COMM_LEN);
	309	* __entry->prev_pid = prev->pid;
	310	* __entry->prev_prio = prev->prio;
823f9124 SR	311	* memcpy(__entry->prev_comm, prev->comm, TASK_COMM_LEN);
823f9124 SR	312	* __entry->next_pid = next->pid;
ef18012b	313	* __entry->next_prio = next->prio;
823f9124 SR	314	* )
	315	*
	316	* *
	317	* * Formatted output of a trace record via TP_printk().
	318	* * This is how the tracepoint will appear under ftrace
	319	* * plugins that make use of this tracepoint.
	320	* *
	321	* * (raw-binary tracing wont actually perform this step.)
	322	* *
	323	*
	324	* TP_printk("task %s:%d [%d] ==> %s:%d [%d]",
	325	* __entry->prev_comm, __entry->prev_pid, __entry->prev_prio,
	326	* __entry->next_comm, __entry->next_pid, __entry->next_prio),
	327	*
	328	* );
	329	*
	330	* This macro construct is thus used for the regular printk format
	331	* tracing setup, it is used to construct a function pointer based
	332	* tracepoint callback (this is used by programmatic plugins and
	333	* can also by used by generic instrumentation like SystemTap), and
	334	* it is also used to expose a structured trace record in
156f5a78	335	* /sys/kernel/debug/tracing/events/.
97419875 JS	336	*
	337	* A set of (un)registration functions can be passed to the variant
	338	* TRACE_EVENT_FN to perform any (un)registration work.
823f9124 SR	339	*/
823f9124 SR	340
091ad365	341	#define DECLARE_EVENT_CLASS(name, proto, args, tstruct, assign, print)
ff038f5c SR	342	#define DEFINE_EVENT(template, name, proto, args) \
ff038f5c SR	343	DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
e5bc9721 SR	344	#define DEFINE_EVENT_PRINT(template, name, proto, args, print) \
e5bc9721 SR	345	DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
ff038f5c	346
30a8fecc	347	#define TRACE_EVENT(name, proto, args, struct, assign, print) \
da4d0302	348	DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
97419875 JS	349	#define TRACE_EVENT_FN(name, proto, args, struct, \
	350	assign, print, reg, unreg) \
	351	DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
7cb2e3ee SR	352
7cb2e3ee SR	353	#endif /* ifdef TRACE_EVENT (see note above) */