[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/errno.h>
#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
b70e4f05	17	#include <linux/errno.h>
97e1c18e MD	18	#include <linux/types.h>
	19	#include <linux/rcupdate.h>
	20
	21	struct module;
	22	struct tracepoint;
	23
38516ab5 SR	24	struct tracepoint_func {
	25	void *func;
	26	void *data;
	27	};
	28
97e1c18e MD	29	struct tracepoint {
	30	const char name; / Tracepoint name */
	31	int state; /* State. */
97419875 JS	32	void (*regfunc)(void);
97419875 JS	33	void (*unregfunc)(void);
38516ab5	34	struct tracepoint_func *funcs;
7e066fb8 MD	35	} __attribute__((aligned(32))); /*
	36	* Aligned on 32 bytes because it is
	37	* globally visible and gcc happily
	38	* align these on the structure size.
	39	* Keep in sync with vmlinux.lds.h.
	40	*/
97e1c18e	41
2e26ca71 SR	42	/*
	43	* Connect a probe to a tracepoint.
	44	* Internal API, should not be used directly.
	45	*/
38516ab5	46	extern int tracepoint_probe_register(const char name, void probe, void *data);
2e26ca71 SR	47
	48	/*
	49	* Disconnect a probe from a tracepoint.
	50	* Internal API, should not be used directly.
	51	*/
38516ab5 SR	52	extern int
38516ab5 SR	53	tracepoint_probe_unregister(const char name, void probe, void *data);
2e26ca71	54
38516ab5 SR	55	extern int tracepoint_probe_register_noupdate(const char name, void probe,
	56	void *data);
	57	extern int tracepoint_probe_unregister_noupdate(const char name, void probe,
	58	void *data);
2e26ca71 SR	59	extern void tracepoint_probe_update_all(void);
	60
	61	struct tracepoint_iter {
	62	struct module *module;
	63	struct tracepoint *tracepoint;
	64	};
	65
	66	extern void tracepoint_iter_start(struct tracepoint_iter *iter);
	67	extern void tracepoint_iter_next(struct tracepoint_iter *iter);
	68	extern void tracepoint_iter_stop(struct tracepoint_iter *iter);
	69	extern void tracepoint_iter_reset(struct tracepoint_iter *iter);
	70	extern int tracepoint_get_iter_range(struct tracepoint **tracepoint,
	71	struct tracepoint begin, struct tracepoint end);
	72
	73	/*
	74	* tracepoint_synchronize_unregister must be called between the last tracepoint
	75	* probe unregistration and the end of module exit to make sure there is no
	76	* caller executing a probe when it is freed.
	77	*/
	78	static inline void tracepoint_synchronize_unregister(void)
	79	{
	80	synchronize_sched();
	81	}
	82
	83	#define PARAMS(args...) args
	84
	85	#ifdef CONFIG_TRACEPOINTS
	86	extern void tracepoint_update_probe_range(struct tracepoint *begin,
	87	struct tracepoint *end);
	88	#else
	89	static inline void tracepoint_update_probe_range(struct tracepoint *begin,
	90	struct tracepoint *end)
	91	{ }
	92	#endif /* CONFIG_TRACEPOINTS */
	93
	94	#endif /* _LINUX_TRACEPOINT_H */
	95
	96	/*
	97	* Note: we keep the TRACE_EVENT and DECLARE_TRACE outside the include
	98	* file ifdef protection.
	99	* This is due to the way trace events work. If a file includes two
	100	* trace event headers under one "CREATE_TRACE_POINTS" the first include
	101	* will override the TRACE_EVENT and break the second include.
	102	*/
	103
ea20d929 SR	104	#ifndef DECLARE_TRACE
ea20d929 SR	105
2939b046	106	#define TP_PROTO(args...) args
8cd09a59	107	#define TP_ARGS(args...) args
97e1c18e MD	108
	109	#ifdef CONFIG_TRACEPOINTS
	110
	111	/*
	112	* it_func[0] is never NULL because there is at least one element in the array
	113	* when the array itself is non NULL.
38516ab5 SR	114	*
	115	* Note, the proto and args passed in includes "__data" as the first parameter.
	116	* The reason for this is to handle the "void" prototype. If a tracepoint
	117	* has a "void" prototype, then it is invalid to declare a function
	118	* as "(void *, void)". The DECLARE_TRACE_NOARGS() will pass in just
	119	* "void data", where as the DECLARE_TRACE() will pass in "void data, proto".
97e1c18e MD	120	*/
	121	#define __DO_TRACE(tp, proto, args) \
	122	do { \
38516ab5 SR	123	struct tracepoint_func *it_func_ptr; \
	124	void *it_func; \
	125	void *__data; \
97e1c18e	126	\
da7b3eab	127	rcu_read_lock_sched_notrace(); \
38516ab5 SR	128	it_func_ptr = rcu_dereference_sched((tp)->funcs); \
38516ab5 SR	129	if (it_func_ptr) { \
97e1c18e	130	do { \
38516ab5 SR	131	it_func = (it_func_ptr)->func; \
	132	__data = (it_func_ptr)->data; \
	133	((void(*)(proto))(it_func))(args); \
	134	} while ((++it_func_ptr)->func); \
97e1c18e	135	} \
da7b3eab	136	rcu_read_unlock_sched_notrace(); \
97e1c18e MD	137	} while (0)
	138
	139	/*
	140	* Make sure the alignment of the structure in the __tracepoints section will
	141	* not add unwanted padding between the beginning of the section and the
	142	* structure. Force alignment to the same alignment as the section start.
	143	*/
38516ab5	144	#define __DECLARE_TRACE(name, proto, args, data_proto, data_args) \
7e066fb8	145	extern struct tracepoint __tracepoint_##name; \
97e1c18e MD	146	static inline void trace_##name(proto) \
97e1c18e MD	147	{ \
97e1c18e MD	148	if (unlikely(__tracepoint_##name.state)) \
97e1c18e MD	149	__DO_TRACE(&__tracepoint_##name, \
38516ab5 SR	150	TP_PROTO(data_proto), \
38516ab5 SR	151	TP_ARGS(data_args)); \
97e1c18e	152	} \
38516ab5 SR	153	static inline int \
38516ab5 SR	154	register_trace_##name(void (probe)(data_proto), void data) \
97e1c18e	155	{ \
38516ab5 SR	156	return tracepoint_probe_register(#name, (void *)probe, \
38516ab5 SR	157	data); \
97e1c18e	158	} \
38516ab5 SR	159	static inline int \
38516ab5 SR	160	unregister_trace_##name(void (probe)(data_proto), void data) \
97e1c18e	161	{ \
38516ab5 SR	162	return tracepoint_probe_unregister(#name, (void *)probe, \
38516ab5 SR	163	data); \
53da59aa	164	} \
38516ab5 SR	165	static inline void \
38516ab5 SR	166	check_trace_callback_type_##name(void (*cb)(data_proto)) \
53da59aa	167	{ \
97e1c18e MD	168	}
97e1c18e MD	169
97419875	170	#define DEFINE_TRACE_FN(name, reg, unreg) \
7e066fb8 MD	171	static const char __tpstrtab_##name[] \
	172	__attribute__((section("__tracepoints_strings"))) = #name; \
	173	struct tracepoint __tracepoint_##name \
	174	__attribute__((section("__tracepoints"), aligned(32))) = \
97419875 JS	175	{ __tpstrtab_##name, 0, reg, unreg, NULL }
	176
	177	#define DEFINE_TRACE(name) \
	178	DEFINE_TRACE_FN(name, NULL, NULL);
7e066fb8 MD	179
	180	#define EXPORT_TRACEPOINT_SYMBOL_GPL(name) \
	181	EXPORT_SYMBOL_GPL(__tracepoint_##name)
	182	#define EXPORT_TRACEPOINT_SYMBOL(name) \
	183	EXPORT_SYMBOL(__tracepoint_##name)
	184
97e1c18e	185	#else /* !CONFIG_TRACEPOINTS */
38516ab5	186	#define __DECLARE_TRACE(name, proto, args, data_proto, data_args) \
97e1c18e MD	187	static inline void trace_##name(proto) \
97e1c18e MD	188	{ } \
38516ab5 SR	189	static inline int \
	190	register_trace_##name(void (*probe)(data_proto), \
	191	void *data) \
97e1c18e MD	192	{ \
	193	return -ENOSYS; \
	194	} \
38516ab5 SR	195	static inline int \
	196	unregister_trace_##name(void (*probe)(data_proto), \
	197	void *data) \
c420970e MD	198	{ \
c420970e MD	199	return -ENOSYS; \
53da59aa	200	} \
38516ab5	201	static inline void check_trace_callback_type_##name(void (*cb)(data_proto)) \
53da59aa	202	{ \
c420970e	203	}
97e1c18e	204
97419875	205	#define DEFINE_TRACE_FN(name, reg, unreg)
7e066fb8 MD	206	#define DEFINE_TRACE(name)
	207	#define EXPORT_TRACEPOINT_SYMBOL_GPL(name)
	208	#define EXPORT_TRACEPOINT_SYMBOL(name)
	209
97e1c18e	210	#endif /* CONFIG_TRACEPOINTS */
38516ab5 SR	211
	212	/*
	213	* The need for the DECLARE_TRACE_NOARGS() is to handle the prototype
	214	* (void). "void" is a special value in a function prototype and can
	215	* not be combined with other arguments. Since the DECLARE_TRACE()
	216	* macro adds a data element at the beginning of the prototype,
	217	* we need a way to differentiate "(void *data, proto)" from
	218	* "(void *data, void)". The second prototype is invalid.
	219	*
	220	* DECLARE_TRACE_NOARGS() passes "void" as the tracepoint prototype
	221	* and "void *__data" as the callback prototype.
	222	*
	223	* DECLARE_TRACE() passes "proto" as the tracepoint protoype and
	224	* "void *__data, proto" as the callback prototype.
	225	*/
	226	#define DECLARE_TRACE_NOARGS(name) \
	227	__DECLARE_TRACE(name, void, , void *__data, __data)
	228
	229	#define DECLARE_TRACE(name, proto, args) \
	230	__DECLARE_TRACE(name, PARAMS(proto), PARAMS(args), \
	231	PARAMS(void *__data, proto), \
	232	PARAMS(__data, args))
	233
ea20d929	234	#endif /* DECLARE_TRACE */
97e1c18e	235
ea20d929	236	#ifndef TRACE_EVENT
823f9124 SR	237	/*
	238	* For use with the TRACE_EVENT macro:
	239	*
	240	* We define a tracepoint, its arguments, its printk format
	241	* and its 'fast binay record' layout.
	242	*
	243	* Firstly, name your tracepoint via TRACE_EVENT(name : the
	244	* 'subsystem_event' notation is fine.
	245	*
	246	* Think about this whole construct as the
	247	* 'trace_sched_switch() function' from now on.
	248	*
	249	*
	250	* TRACE_EVENT(sched_switch,
	251	*
	252	* *
	253	* * A function has a regular function arguments
	254	* * prototype, declare it via TP_PROTO():
	255	* *
	256	*
ef18012b SR	257	* TP_PROTO(struct rq rq, struct task_struct prev,
ef18012b SR	258	* struct task_struct *next),
823f9124 SR	259	*
	260	* *
	261	* * Define the call signature of the 'function'.
	262	* * (Design sidenote: we use this instead of a
	263	* * TP_PROTO1/TP_PROTO2/TP_PROTO3 ugliness.)
	264	* *
	265	*
ef18012b	266	* TP_ARGS(rq, prev, next),
823f9124 SR	267	*
	268	* *
	269	* * Fast binary tracing: define the trace record via
	270	* * TP_STRUCT__entry(). You can think about it like a
	271	* * regular C structure local variable definition.
	272	* *
	273	* * This is how the trace record is structured and will
	274	* * be saved into the ring buffer. These are the fields
	275	* * that will be exposed to user-space in
156f5a78	276	* * /sys/kernel/debug/tracing/events/<*>/format.
823f9124 SR	277	* *
	278	* * The declared 'local variable' is called '__entry'
	279	* *
	280	* * __field(pid_t, prev_prid) is equivalent to a standard declariton:
	281	* *
	282	* * pid_t prev_pid;
	283	* *
	284	* * __array(char, prev_comm, TASK_COMM_LEN) is equivalent to:
	285	* *
	286	* * char prev_comm[TASK_COMM_LEN];
	287	* *
	288	*
	289	* TP_STRUCT__entry(
	290	* __array( char, prev_comm, TASK_COMM_LEN )
	291	* __field( pid_t, prev_pid )
	292	* __field( int, prev_prio )
	293	* __array( char, next_comm, TASK_COMM_LEN )
	294	* __field( pid_t, next_pid )
	295	* __field( int, next_prio )
	296	* ),
	297	*
	298	* *
	299	* * Assign the entry into the trace record, by embedding
	300	* * a full C statement block into TP_fast_assign(). You
	301	* * can refer to the trace record as '__entry' -
	302	* * otherwise you can put arbitrary C code in here.
	303	* *
	304	* * Note: this C code will execute every time a trace event
	305	* * happens, on an active tracepoint.
	306	* *
	307	*
ef18012b SR	308	* TP_fast_assign(
	309	* memcpy(__entry->next_comm, next->comm, TASK_COMM_LEN);
	310	* __entry->prev_pid = prev->pid;
	311	* __entry->prev_prio = prev->prio;
823f9124 SR	312	* memcpy(__entry->prev_comm, prev->comm, TASK_COMM_LEN);
823f9124 SR	313	* __entry->next_pid = next->pid;
ef18012b	314	* __entry->next_prio = next->prio;
823f9124 SR	315	* )
	316	*
	317	* *
	318	* * Formatted output of a trace record via TP_printk().
	319	* * This is how the tracepoint will appear under ftrace
	320	* * plugins that make use of this tracepoint.
	321	* *
	322	* * (raw-binary tracing wont actually perform this step.)
	323	* *
	324	*
	325	* TP_printk("task %s:%d [%d] ==> %s:%d [%d]",
	326	* __entry->prev_comm, __entry->prev_pid, __entry->prev_prio,
	327	* __entry->next_comm, __entry->next_pid, __entry->next_prio),
	328	*
	329	* );
	330	*
	331	* This macro construct is thus used for the regular printk format
	332	* tracing setup, it is used to construct a function pointer based
	333	* tracepoint callback (this is used by programmatic plugins and
	334	* can also by used by generic instrumentation like SystemTap), and
	335	* it is also used to expose a structured trace record in
156f5a78	336	* /sys/kernel/debug/tracing/events/.
97419875 JS	337	*
	338	* A set of (un)registration functions can be passed to the variant
	339	* TRACE_EVENT_FN to perform any (un)registration work.
823f9124 SR	340	*/
823f9124 SR	341
091ad365	342	#define DECLARE_EVENT_CLASS(name, proto, args, tstruct, assign, print)
ff038f5c SR	343	#define DEFINE_EVENT(template, name, proto, args) \
ff038f5c SR	344	DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
e5bc9721 SR	345	#define DEFINE_EVENT_PRINT(template, name, proto, args, print) \
e5bc9721 SR	346	DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
ff038f5c	347
30a8fecc	348	#define TRACE_EVENT(name, proto, args, struct, assign, print) \
da4d0302	349	DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
97419875 JS	350	#define TRACE_EVENT_FN(name, proto, args, struct, \
	351	assign, print, reg, unreg) \
	352	DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
7cb2e3ee SR	353
7cb2e3ee SR	354	#endif /* ifdef TRACE_EVENT (see note above) */