Add probe provider unregister function

[lttng-ust.git] / include / lttng / ust-events.h

#ifndef _LTTNG_UST_EVENTS_H
#define _LTTNG_UST_EVENTS_H

/*
 * lttng/ust-events.h
 *
 * Copyright 2010-2012 (c) - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
 *
 * Holds LTTng per-session event registry.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

#include <urcu/list.h>
#include <urcu/hlist.h>
#include <stdint.h>
#include <lttng/ust-config.h>
#include <lttng/ust-abi.h>
#include <lttng/ust-tracer.h>
#include <lttng/ust-endian.h>
#include <float.h>
#include <errno.h>
#include <urcu/ref.h>
#include <pthread.h>

#ifdef __cplusplus
extern "C" {
#endif

#define LTTNG_UST_UUID_LEN		16

/*
 * Tracepoint provider version. Compatibility based on the major number.
 * Older tracepoint providers can always register to newer lttng-ust
 * library, but the opposite is rejected: a newer tracepoint provider is
 * rejected by an older lttng-ust library.
 */
#define LTTNG_UST_PROVIDER_MAJOR	1
#define LTTNG_UST_PROVIDER_MINOR	0

struct lttng_channel;
struct lttng_session;
struct lttng_ust_lib_ring_buffer_ctx;
struct lttng_ust_context_app;
struct lttng_event_field;

/*
 * Data structures used by tracepoint event declarations, and by the
 * tracer. Those structures have padding for future extension.
 */

/*
 * LTTng client type enumeration. Used by the consumer to map the
 * callbacks from its own address space.
 */
enum lttng_client_types {
	LTTNG_CLIENT_METADATA = 0,
	LTTNG_CLIENT_DISCARD = 1,
	LTTNG_CLIENT_OVERWRITE = 2,
	LTTNG_CLIENT_DISCARD_RT = 3,
	LTTNG_CLIENT_OVERWRITE_RT = 4,
	LTTNG_NR_CLIENT_TYPES,
};

/* Type description */

/* Update the astract_types name table in lttng-types.c along with this enum */
enum lttng_abstract_types {
	atype_integer,
	atype_enum,
	atype_array,
	atype_sequence,
	atype_string,
	atype_float,
	atype_dynamic,
	atype_struct,
	NR_ABSTRACT_TYPES,
};

/* Update the string_encodings name table in lttng-types.c along with this enum */
enum lttng_string_encodings {
	lttng_encode_none = 0,
	lttng_encode_UTF8 = 1,
	lttng_encode_ASCII = 2,
	NR_STRING_ENCODINGS,
};

struct lttng_enum_value {
	unsigned long long value;
	unsigned int signedness:1;
};

enum lttng_enum_entry_options {
	LTTNG_ENUM_ENTRY_OPTION_IS_AUTO = 1U << 0,
};

#define LTTNG_UST_ENUM_ENTRY_PADDING	16
struct lttng_enum_entry {
	struct lttng_enum_value start, end; /* start and end are inclusive */
	const char *string;
	union {
		struct {
			unsigned int options;
		} LTTNG_PACKED extra;
		char padding[LTTNG_UST_ENUM_ENTRY_PADDING];
	} u;
};

#define __type_integer(_type, _byte_order, _base, _encoding)	\
	{							\
	  .atype = atype_integer,				\
	  .u =							\
		{						\
		  .basic = 					\
			{					\
			  .integer =				\
				{				\
				  .size = sizeof(_type) * CHAR_BIT,		\
				  .alignment = lttng_alignof(_type) * CHAR_BIT,	\
				  .signedness = lttng_is_signed_type(_type),	\
				  .reverse_byte_order = _byte_order != BYTE_ORDER, \
				  .base = _base,				\
				  .encoding = lttng_encode_##_encoding,		\
				}				\
			}					\
		},						\
	}							\

#define LTTNG_UST_INTEGER_TYPE_PADDING	24
struct lttng_integer_type {
	unsigned int size;		/* in bits */
	unsigned short alignment;	/* in bits */
	unsigned int signedness:1;
	unsigned int reverse_byte_order:1;
	unsigned int base;		/* 2, 8, 10, 16, for pretty print */
	enum lttng_string_encodings encoding;
	char padding[LTTNG_UST_INTEGER_TYPE_PADDING];
};

/*
 * Only float and double are supported. long double is not supported at
 * the moment.
 */
#define _float_mant_dig(_type)						\
	(sizeof(_type) == sizeof(float) ? FLT_MANT_DIG			\
		: (sizeof(_type) == sizeof(double) ? DBL_MANT_DIG	\
		: 0))

#define __type_float(_type)					\
	{							\
	  .atype = atype_float,					\
	  .u =							\
		{						\
		  .basic =					\
			{					\
			  ._float =				\
				{				\
				  .exp_dig = sizeof(_type) * CHAR_BIT		\
						  - _float_mant_dig(_type),	\
				  .mant_dig = _float_mant_dig(_type),		\
				  .alignment = lttng_alignof(_type) * CHAR_BIT,	\
				  .reverse_byte_order = BYTE_ORDER != FLOAT_WORD_ORDER,	\
				}				\
			}					\
		},						\
	}							\

#define LTTNG_UST_FLOAT_TYPE_PADDING	24
struct lttng_float_type {
	unsigned int exp_dig;		/* exponent digits, in bits */
	unsigned int mant_dig;		/* mantissa digits, in bits */
	unsigned short alignment;	/* in bits */
	unsigned int reverse_byte_order:1;
	char padding[LTTNG_UST_FLOAT_TYPE_PADDING];
};

#define LTTNG_UST_BASIC_TYPE_PADDING	128
union _lttng_basic_type {
	struct lttng_integer_type integer;
	struct {
		const struct lttng_enum_desc *desc;	/* Enumeration mapping */
		struct lttng_integer_type container_type;
	} enumeration;
	struct {
		enum lttng_string_encodings encoding;
	} string;
	struct lttng_float_type _float;
	char padding[LTTNG_UST_BASIC_TYPE_PADDING];
};

struct lttng_basic_type {
	enum lttng_abstract_types atype;
	union {
		union _lttng_basic_type basic;
	} u;
};

#define LTTNG_UST_TYPE_PADDING	128
struct lttng_type {
	enum lttng_abstract_types atype;
	union {
		union _lttng_basic_type basic;
		struct {
			struct lttng_basic_type elem_type;
			unsigned int length;		/* num. elems. */
		} array;
		struct {
			struct lttng_basic_type length_type;
			struct lttng_basic_type elem_type;
		} sequence;
		struct {
			uint32_t nr_fields;
			struct lttng_event_field *fields;	/* Array of fields. */
		} _struct;
		char padding[LTTNG_UST_TYPE_PADDING];
	} u;
};

#define LTTNG_UST_ENUM_TYPE_PADDING	24
struct lttng_enum_desc {
	const char *name;
	const struct lttng_enum_entry *entries;
	unsigned int nr_entries;
	char padding[LTTNG_UST_ENUM_TYPE_PADDING];
};

/*
 * Event field description
 *
 * IMPORTANT: this structure is part of the ABI between the probe and
 * UST. Fields need to be only added at the end, never reordered, never
 * removed.
 */

#define LTTNG_UST_EVENT_FIELD_PADDING	28
struct lttng_event_field {
	const char *name;
	struct lttng_type type;
	unsigned int nowrite;	/* do not write into trace */
	char padding[LTTNG_UST_EVENT_FIELD_PADDING];
};

enum lttng_ust_dynamic_type {
	LTTNG_UST_DYNAMIC_TYPE_NONE,
	LTTNG_UST_DYNAMIC_TYPE_S8,
	LTTNG_UST_DYNAMIC_TYPE_S16,
	LTTNG_UST_DYNAMIC_TYPE_S32,
	LTTNG_UST_DYNAMIC_TYPE_S64,
	LTTNG_UST_DYNAMIC_TYPE_U8,
	LTTNG_UST_DYNAMIC_TYPE_U16,
	LTTNG_UST_DYNAMIC_TYPE_U32,
	LTTNG_UST_DYNAMIC_TYPE_U64,
	LTTNG_UST_DYNAMIC_TYPE_FLOAT,
	LTTNG_UST_DYNAMIC_TYPE_DOUBLE,
	LTTNG_UST_DYNAMIC_TYPE_STRING,
	_NR_LTTNG_UST_DYNAMIC_TYPES,
};

struct lttng_ctx_value {
	enum lttng_ust_dynamic_type sel;
	union {
		int64_t s64;
		const char *str;
		double d;
	} u;
};

struct lttng_perf_counter_field;

#define LTTNG_UST_CTX_FIELD_PADDING	40
struct lttng_ctx_field {
	struct lttng_event_field event_field;
	size_t (*get_size)(struct lttng_ctx_field *field, size_t offset);
	void (*record)(struct lttng_ctx_field *field,
		       struct lttng_ust_lib_ring_buffer_ctx *ctx,
		       struct lttng_channel *chan);
	void (*get_value)(struct lttng_ctx_field *field,
			 struct lttng_ctx_value *value);
	union {
		struct lttng_perf_counter_field *perf_counter;
		char padding[LTTNG_UST_CTX_FIELD_PADDING];
	} u;
	void (*destroy)(struct lttng_ctx_field *field);
	char *field_name;	/* Has ownership, dynamically allocated. */
};

#define LTTNG_UST_CTX_PADDING	20
struct lttng_ctx {
	struct lttng_ctx_field *fields;
	unsigned int nr_fields;
	unsigned int allocated_fields;
	unsigned int largest_align;
	char padding[LTTNG_UST_CTX_PADDING];
};

#define LTTNG_UST_EVENT_DESC_PADDING	40
struct lttng_event_desc {
	const char *name;
	void (*probe_callback)(void);
	const struct lttng_event_ctx *ctx;	/* context */
	const struct lttng_event_field *fields;	/* event payload */
	unsigned int nr_fields;
	const int **loglevel;
	const char *signature;	/* Argument types/names received */
	union {
		struct {
			const char **model_emf_uri;
		} ext;
		char padding[LTTNG_UST_EVENT_DESC_PADDING];
	} u;
};

#define LTTNG_UST_PROBE_DESC_PADDING	12
struct lttng_probe_desc {
	const char *provider;
	const struct lttng_event_desc **event_desc;
	unsigned int nr_events;
	struct cds_list_head head;		/* chain registered probes */
	struct cds_list_head lazy_init_head;
	int lazy;				/* lazy registration */
	uint32_t major;
	uint32_t minor;
	char padding[LTTNG_UST_PROBE_DESC_PADDING];
};

/* Data structures used by the tracer. */

enum lttng_enabler_type {
	LTTNG_ENABLER_STAR_GLOB,
	LTTNG_ENABLER_EVENT,
};

/*
 * Enabler field, within whatever object is enabling an event. Target of
 * backward reference.
 */
struct lttng_enabler {
	enum lttng_enabler_type type;

	/* head list of struct lttng_ust_filter_bytecode_node */
	struct cds_list_head filter_bytecode_head;
	/* head list of struct lttng_ust_excluder_node */
	struct cds_list_head excluder_head;
	struct cds_list_head node;	/* per-session list of enablers */

	struct lttng_ust_event event_param;
	struct lttng_channel *chan;
	struct lttng_ctx *ctx;
	unsigned int enabled:1;
};

struct tp_list_entry {
	struct lttng_ust_tracepoint_iter tp;
	struct cds_list_head head;
};

struct lttng_ust_tracepoint_list {
	struct tp_list_entry *iter;
	struct cds_list_head head;
};

struct tp_field_list_entry {
	struct lttng_ust_field_iter field;
	struct cds_list_head head;
};

struct lttng_ust_field_list {
	struct tp_field_list_entry *iter;
	struct cds_list_head head;
};

struct ust_pending_probe;
struct lttng_event;

struct lttng_ust_filter_bytecode_node {
	struct cds_list_head node;
	struct lttng_enabler *enabler;
	/*
	 * struct lttng_ust_filter_bytecode has var. sized array, must
	 * be last field.
	 */
	struct lttng_ust_filter_bytecode bc;
};

struct lttng_ust_excluder_node {
	struct cds_list_head node;
	struct lttng_enabler *enabler;
	/*
	 * struct lttng_ust_event_exclusion had variable sized array,
	 * must be last field.
	 */
	struct lttng_ust_event_exclusion excluder;
};
/*
 * Filter return value masks.
 */
enum lttng_filter_ret {
	LTTNG_FILTER_DISCARD = 0,
	LTTNG_FILTER_RECORD_FLAG = (1ULL << 0),
	/* Other bits are kept for future use. */
};

struct lttng_bytecode_runtime {
	/* Associated bytecode */
	struct lttng_ust_filter_bytecode_node *bc;
	uint64_t (*filter)(void *filter_data, const char *filter_stack_data);
	int link_failed;
	struct cds_list_head node;	/* list of bytecode runtime in event */
	struct lttng_session *session;
};

/*
 * Objects in a linked-list of enablers, owned by an event.
 */
struct lttng_enabler_ref {
	struct cds_list_head node;		/* enabler ref list */
	struct lttng_enabler *ref;		/* backward ref */
};

/*
 * lttng_event structure is referred to by the tracing fast path. It
 * must be kept small.
 *
 * IMPORTANT: this structure is part of the ABI between the probe and
 * UST. Fields need to be only added at the end, never reordered, never
 * removed.
 */
struct lttng_event {
	/* LTTng-UST 2.0 starts here */
	unsigned int id;
	struct lttng_channel *chan;
	int enabled;
	const struct lttng_event_desc *desc;
	void *_deprecated1;
	struct lttng_ctx *ctx;
	enum lttng_ust_instrumentation instrumentation;
	struct cds_list_head node;		/* Event list in session */
	struct cds_list_head _deprecated2;
	void *_deprecated3;
	unsigned int _deprecated4:1;

	/* LTTng-UST 2.1 starts here */
	/* list of struct lttng_bytecode_runtime, sorted by seqnum */
	struct cds_list_head bytecode_runtime_head;
	int has_enablers_without_bytecode;
	/* Backward references: list of lttng_enabler_ref (ref to enablers) */
	struct cds_list_head enablers_ref_head;
	struct cds_hlist_node hlist;	/* session ht of events */
	int registered;			/* has reg'd tracepoint probe */
};

struct lttng_enum {
	const struct lttng_enum_desc *desc;
	struct lttng_session *session;
	struct cds_list_head node;	/* Enum list in session */
	struct cds_hlist_node hlist;	/* Session ht of enums */
	uint64_t id;			/* Enumeration ID in sessiond */
};

struct channel;
struct lttng_ust_shm_handle;

/*
 * IMPORTANT: this structure is part of the ABI between the probe and
 * UST. Fields need to be only added at the end, never reordered, never
 * removed.
 */
struct lttng_channel_ops {
	struct lttng_channel *(*channel_create)(const char *name,
			void *buf_addr,
			size_t subbuf_size, size_t num_subbuf,
			unsigned int switch_timer_interval,
			unsigned int read_timer_interval,
			unsigned char *uuid,
			uint32_t chan_id,
			const int *stream_fds, int nr_stream_fds,
			int64_t blocking_timeout);
	void (*channel_destroy)(struct lttng_channel *chan);
	union {
		void *_deprecated1;
		unsigned long has_strcpy:1;		/* ABI has strcpy */
	} u;
	void *_deprecated2;
	int (*event_reserve)(struct lttng_ust_lib_ring_buffer_ctx *ctx,
			     uint32_t event_id);
	void (*event_commit)(struct lttng_ust_lib_ring_buffer_ctx *ctx);
	void (*event_write)(struct lttng_ust_lib_ring_buffer_ctx *ctx,
			const void *src, size_t len);
	/*
	 * packet_avail_size returns the available size in the current
	 * packet. Note that the size returned is only a hint, since it
	 * may change due to concurrent writes.
	 */
	size_t (*packet_avail_size)(struct channel *chan,
				    struct lttng_ust_shm_handle *handle);
	//wait_queue_head_t *(*get_reader_wait_queue)(struct channel *chan);
	//wait_queue_head_t *(*get_hp_wait_queue)(struct channel *chan);
	int (*is_finalized)(struct channel *chan);
	int (*is_disabled)(struct channel *chan);
	int (*flush_buffer)(struct channel *chan, struct lttng_ust_shm_handle *handle);
	void (*event_strcpy)(struct lttng_ust_lib_ring_buffer_ctx *ctx,
			const char *src, size_t len);
};

/*
 * IMPORTANT: this structure is part of the ABI between the probe and
 * UST. Fields need to be only added at the end, never reordered, never
 * removed.
 */
struct lttng_channel {
	/*
	 * The pointers located in this private data are NOT safe to be
	 * dereferenced by the consumer. The only operations the
	 * consumer process is designed to be allowed to do is to read
	 * and perform subbuffer flush.
	 */
	struct channel *chan;		/* Channel buffers */
	int enabled;
	struct lttng_ctx *ctx;
	/* Event ID management */
	struct lttng_session *session;
	int objd;			/* Object associated to channel */
	unsigned int _deprecated1;
	unsigned int _deprecated2;
	struct cds_list_head node;	/* Channel list in session */
	const struct lttng_channel_ops *ops;
	int header_type;		/* 0: unset, 1: compact, 2: large */
	struct lttng_ust_shm_handle *handle;	/* shared-memory handle */
	unsigned int _deprecated3:1;

	/* Channel ID */
	unsigned int id;
	enum lttng_ust_chan_type type;
	unsigned char uuid[LTTNG_UST_UUID_LEN]; /* Trace session unique ID */
	int tstate:1;			/* Transient enable state */
};

#define LTTNG_UST_STACK_CTX_PADDING	32
struct lttng_stack_ctx {
	struct lttng_event *event;
	struct lttng_ctx *chan_ctx;	/* RCU dereferenced. */
	struct lttng_ctx *event_ctx;	/* RCU dereferenced. */
	char padding[LTTNG_UST_STACK_CTX_PADDING];
};

#define LTTNG_UST_EVENT_HT_BITS		12
#define LTTNG_UST_EVENT_HT_SIZE		(1U << LTTNG_UST_EVENT_HT_BITS)

struct lttng_ust_event_ht {
	struct cds_hlist_head table[LTTNG_UST_EVENT_HT_SIZE];
};

#define LTTNG_UST_ENUM_HT_BITS		12
#define LTTNG_UST_ENUM_HT_SIZE		(1U << LTTNG_UST_ENUM_HT_BITS)

struct lttng_ust_enum_ht {
	struct cds_hlist_head table[LTTNG_UST_ENUM_HT_SIZE];
};

/*
 * IMPORTANT: this structure is part of the ABI between the probe and
 * UST. Fields need to be only added at the end, never reordered, never
 * removed.
 */
struct lttng_session {
	int active;				/* Is trace session active ? */
	int been_active;			/* Been active ? */
	int objd;				/* Object associated */
	void *_deprecated1;
	struct cds_list_head chan_head;		/* Channel list head */
	struct cds_list_head events_head;	/* list of events */
	struct cds_list_head _deprecated2;
	struct cds_list_head node;		/* Session list */
	int _deprecated3;
	unsigned int _deprecated4:1;

	/* New UST 2.1 */
	/* List of enablers */
	struct cds_list_head enablers_head;
	struct lttng_ust_event_ht events_ht;	/* ht of events */
	void *owner;				/* object owner */
	int tstate:1;				/* Transient enable state */

	/* New UST 2.4 */
	int statedump_pending:1;

	/* New UST 2.8 */
	struct lttng_ust_enum_ht enums_ht;	/* ht of enumerations */
	struct cds_list_head enums_head;
	struct lttng_ctx *ctx;			/* contexts for filters. */
};

struct lttng_transport {
	char *name;
	struct cds_list_head node;
	struct lttng_channel_ops ops;
	const struct lttng_ust_lib_ring_buffer_config *client_config;
};

struct lttng_session *lttng_session_create(void);
int lttng_session_enable(struct lttng_session *session);
int lttng_session_disable(struct lttng_session *session);
int lttng_session_statedump(struct lttng_session *session);
void lttng_session_destroy(struct lttng_session *session);

struct lttng_channel *lttng_channel_create(struct lttng_session *session,
				       const char *transport_name,
				       void *buf_addr,
				       size_t subbuf_size, size_t num_subbuf,
				       unsigned int switch_timer_interval,
				       unsigned int read_timer_interval,
				       int **shm_fd, int **wait_fd,
				       uint64_t **memory_map_size,
				       struct lttng_channel *chan_priv_init);

int lttng_channel_enable(struct lttng_channel *channel);
int lttng_channel_disable(struct lttng_channel *channel);

struct lttng_enabler *lttng_enabler_create(enum lttng_enabler_type type,
		struct lttng_ust_event *event_param,
		struct lttng_channel *chan);
int lttng_enabler_enable(struct lttng_enabler *enabler);
int lttng_enabler_disable(struct lttng_enabler *enabler);
int lttng_enabler_attach_bytecode(struct lttng_enabler *enabler,
		struct lttng_ust_filter_bytecode_node *bytecode);
int lttng_enabler_attach_context(struct lttng_enabler *enabler,
		struct lttng_ust_context *ctx);
int lttng_enabler_attach_exclusion(struct lttng_enabler *enabler,
		struct lttng_ust_excluder_node *excluder);

int lttng_attach_context(struct lttng_ust_context *context_param,
		union ust_args *uargs,
		struct lttng_ctx **ctx, struct lttng_session *session);
int lttng_session_context_init(struct lttng_ctx **ctx);

void lttng_transport_register(struct lttng_transport *transport);
void lttng_transport_unregister(struct lttng_transport *transport);

void synchronize_trace(void);

int lttng_probe_register(struct lttng_probe_desc *desc);
void lttng_probe_unregister(struct lttng_probe_desc *desc);
void lttng_probe_provider_unregister_events(struct lttng_probe_desc *desc);
int lttng_fix_pending_events(void);
int lttng_probes_init(void);
void lttng_probes_exit(void);
int lttng_find_context(struct lttng_ctx *ctx, const char *name);
int lttng_get_context_index(struct lttng_ctx *ctx, const char *name);
struct lttng_ctx_field *lttng_append_context(struct lttng_ctx **ctx_p);
void lttng_context_update(struct lttng_ctx *ctx);
void lttng_remove_context_field(struct lttng_ctx **ctx_p,
				struct lttng_ctx_field *field);
void lttng_destroy_context(struct lttng_ctx *ctx);
int lttng_add_vtid_to_ctx(struct lttng_ctx **ctx);
int lttng_add_vpid_to_ctx(struct lttng_ctx **ctx);
int lttng_add_pthread_id_to_ctx(struct lttng_ctx **ctx);
int lttng_add_procname_to_ctx(struct lttng_ctx **ctx);
int lttng_add_ip_to_ctx(struct lttng_ctx **ctx);
int lttng_add_cpu_id_to_ctx(struct lttng_ctx **ctx);
int lttng_add_dyntest_to_ctx(struct lttng_ctx **ctx);
void lttng_context_vtid_reset(void);
void lttng_context_vpid_reset(void);

#ifdef LTTNG_UST_HAVE_PERF_EVENT
int lttng_add_perf_counter_to_ctx(uint32_t type,
				  uint64_t config,
				  const char *name,
				  struct lttng_ctx **ctx);
int lttng_perf_counter_init(void);
void lttng_perf_counter_exit(void);
#else /* #ifdef LTTNG_UST_HAVE_PERF_EVENT */
static inline
int lttng_add_perf_counter_to_ctx(uint32_t type,
				  uint64_t config,
				  const char *name,
				  struct lttng_ctx **ctx)
{
	return -ENOSYS;
}
static inline
int lttng_perf_counter_init(void)
{
	return 0;
}
static inline
void lttng_perf_counter_exit(void)
{
}
#endif /* #else #ifdef LTTNG_UST_HAVE_PERF_EVENT */

extern const struct lttng_ust_client_lib_ring_buffer_client_cb *lttng_client_callbacks_metadata;
extern const struct lttng_ust_client_lib_ring_buffer_client_cb *lttng_client_callbacks_discard;
extern const struct lttng_ust_client_lib_ring_buffer_client_cb *lttng_client_callbacks_overwrite;

struct lttng_transport *lttng_transport_find(const char *name);

int lttng_probes_get_event_list(struct lttng_ust_tracepoint_list *list);
void lttng_probes_prune_event_list(struct lttng_ust_tracepoint_list *list);
struct lttng_ust_tracepoint_iter *
	lttng_ust_tracepoint_list_get_iter_next(struct lttng_ust_tracepoint_list *list);
int lttng_probes_get_field_list(struct lttng_ust_field_list *list);
void lttng_probes_prune_field_list(struct lttng_ust_field_list *list);
struct lttng_ust_field_iter *
	lttng_ust_field_list_get_iter_next(struct lttng_ust_field_list *list);

void lttng_filter_event_link_bytecode(struct lttng_event *event);
void lttng_enabler_event_link_bytecode(struct lttng_event *event,
		struct lttng_enabler *enabler);
void lttng_free_event_filter_runtime(struct lttng_event *event);
void lttng_filter_sync_state(struct lttng_bytecode_runtime *runtime);

struct cds_list_head *lttng_get_probe_list_head(void);
int lttng_session_active(void);

typedef int (*t_statedump_func_ptr)(struct lttng_session *session);
void lttng_handle_pending_statedump(void *owner);
struct cds_list_head *_lttng_get_sessions(void);
struct lttng_enum *lttng_ust_enum_get(struct lttng_session *session,
		const char *enum_name);

void lttng_ust_dl_update(void *ip);
void lttng_ust_fixup_fd_tracker_tls(void);

/* For backward compatibility. Leave those exported symbols in place. */
extern struct lttng_ctx *lttng_static_ctx;
void lttng_context_init(void);
void lttng_context_exit(void);

#ifdef __cplusplus
}
#endif

#endif /* _LTTNG_UST_EVENTS_H */