[lttng-ust.git] / include / lttng / ringbuffer-config.h

#ifndef _LTTNG_RING_BUFFER_CONFIG_H
#define _LTTNG_RING_BUFFER_CONFIG_H

/*
 * lttng/ringbuffer-config.h
 *
 * Copyright (C) 2010 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
 *
 * Ring buffer configuration header. Note: after declaring the standard inline
 * functions, clients should also include linux/ringbuffer/api.h.
 *
 * 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.
 */

#include <errno.h>
#include "lttng/ust-tracer.h"
#include <stdint.h>
#include <stddef.h>
#include <urcu/arch.h>
#include <string.h>
#include "lttng/align.h"

struct lttng_ust_lib_ring_buffer;
struct channel;
struct lttng_ust_lib_ring_buffer_config;
struct lttng_ust_lib_ring_buffer_ctx;
struct lttng_ust_shm_handle *handle;

/*
 * Ring buffer client callbacks. Only used by slow path, never on fast path.
 * For the fast path, record_header_size(), ring_buffer_clock_read() should be
 * provided as inline functions too.  These may simply return 0 if not used by
 * the client.
 */
struct lttng_ust_lib_ring_buffer_client_cb {
	/* Mandatory callbacks */

	/* A static inline version is also required for fast path */
	uint64_t (*ring_buffer_clock_read) (struct channel *chan);
	size_t (*record_header_size) (const struct lttng_ust_lib_ring_buffer_config *config,
				      struct channel *chan, size_t offset,
				      size_t *pre_header_padding,
				      struct lttng_ust_lib_ring_buffer_ctx *ctx);

	/* Slow path only, at subbuffer switch */
	size_t (*subbuffer_header_size) (void);
	void (*buffer_begin) (struct lttng_ust_lib_ring_buffer *buf, uint64_t tsc,
			      unsigned int subbuf_idx,
			      struct lttng_ust_shm_handle *handle);
	void (*buffer_end) (struct lttng_ust_lib_ring_buffer *buf, uint64_t tsc,
			    unsigned int subbuf_idx, unsigned long data_size,
			    struct lttng_ust_shm_handle *handle);

	/* Optional callbacks (can be set to NULL) */

	/* Called at buffer creation/finalize */
	int (*buffer_create) (struct lttng_ust_lib_ring_buffer *buf, void *priv,
			      int cpu, const char *name,
			      struct lttng_ust_shm_handle *handle);
	/*
	 * Clients should guarantee that no new reader handle can be opened
	 * after finalize.
	 */
	void (*buffer_finalize) (struct lttng_ust_lib_ring_buffer *buf,
				 void *priv, int cpu,
				 struct lttng_ust_shm_handle *handle);

	/*
	 * Extract header length, payload length and timestamp from event
	 * record. Used by buffer iterators. Timestamp is only used by channel
	 * iterator.
	 */
	void (*record_get) (const struct lttng_ust_lib_ring_buffer_config *config,
			    struct channel *chan, struct lttng_ust_lib_ring_buffer *buf,
			    size_t offset, size_t *header_len,
			    size_t *payload_len, uint64_t *timestamp,
			    struct lttng_ust_shm_handle *handle);
};

/*
 * Ring buffer instance configuration.
 *
 * Declare as "static const" within the client object to ensure the inline fast
 * paths can be optimized.
 *
 * alloc/sync pairs:
 *
 * RING_BUFFER_ALLOC_PER_CPU and RING_BUFFER_SYNC_PER_CPU :
 *   Per-cpu buffers with per-cpu synchronization. Tracing must be performed
 *   with preemption disabled (lib_ring_buffer_get_cpu() and
 *   lib_ring_buffer_put_cpu()).
 *
 * RING_BUFFER_ALLOC_PER_CPU and RING_BUFFER_SYNC_GLOBAL :
 *   Per-cpu buffer with global synchronization. Tracing can be performed with
 *   preemption enabled, statistically stays on the local buffers.
 *
 * RING_BUFFER_ALLOC_GLOBAL and RING_BUFFER_SYNC_PER_CPU :
 *   Should only be used for buffers belonging to a single thread or protected
 *   by mutual exclusion by the client. Note that periodical sub-buffer switch
 *   should be disabled in this kind of configuration.
 *
 * RING_BUFFER_ALLOC_GLOBAL and RING_BUFFER_SYNC_GLOBAL :
 *   Global shared buffer with global synchronization.
 *
 * wakeup:
 *
 * RING_BUFFER_WAKEUP_BY_TIMER uses per-cpu deferrable timers to poll the
 * buffers and wake up readers if data is ready. Mainly useful for tracers which
 * don't want to call into the wakeup code on the tracing path. Use in
 * combination with "read_timer_interval" channel_create() argument.
 *
 * RING_BUFFER_WAKEUP_BY_WRITER directly wakes up readers when a subbuffer is
 * ready to read. Lower latencies before the reader is woken up. Mainly suitable
 * for drivers.
 *
 * RING_BUFFER_WAKEUP_NONE does not perform any wakeup whatsoever. The client
 * has the responsibility to perform wakeups.
 */
#define LTTNG_UST_RING_BUFFER_CONFIG_PADDING	32
struct lttng_ust_lib_ring_buffer_config {
	enum {
		RING_BUFFER_ALLOC_PER_CPU,
		RING_BUFFER_ALLOC_GLOBAL,
	} alloc;
	enum {
		RING_BUFFER_SYNC_PER_CPU,	/* Wait-free */
		RING_BUFFER_SYNC_GLOBAL,	/* Lock-free */
	} sync;
	enum {
		RING_BUFFER_OVERWRITE,		/* Overwrite when buffer full */
		RING_BUFFER_DISCARD,		/* Discard when buffer full */
	} mode;
	enum {
		RING_BUFFER_SPLICE,
		RING_BUFFER_MMAP,
		RING_BUFFER_READ,		/* TODO */
		RING_BUFFER_ITERATOR,
		RING_BUFFER_NONE,
	} output;
	enum {
		RING_BUFFER_PAGE,
		RING_BUFFER_VMAP,		/* TODO */
		RING_BUFFER_STATIC,		/* TODO */
	} backend;
	enum {
		RING_BUFFER_NO_OOPS_CONSISTENCY,
		RING_BUFFER_OOPS_CONSISTENCY,
	} oops;
	enum {
		RING_BUFFER_IPI_BARRIER,
		RING_BUFFER_NO_IPI_BARRIER,
	} ipi;
	enum {
		RING_BUFFER_WAKEUP_BY_TIMER,	/* wake up performed by timer */
		RING_BUFFER_WAKEUP_BY_WRITER,	/*
						 * writer wakes up reader,
						 * not lock-free
						 * (takes spinlock).
						 */
	} wakeup;
	/*
	 * tsc_bits: timestamp bits saved at each record.
	 *   0 and 64 disable the timestamp compression scheme.
	 */
	unsigned int tsc_bits;
	struct lttng_ust_lib_ring_buffer_client_cb cb;
	/*
	 * client_type is used by the consumer process (which is in a
	 * different address space) to lookup the appropriate client
	 * callbacks and update the cb pointers.
	 */
	int client_type;
	char padding[LTTNG_UST_RING_BUFFER_CONFIG_PADDING];
};

/*
 * ring buffer context
 *
 * Context passed to lib_ring_buffer_reserve(), lib_ring_buffer_commit(),
 * lib_ring_buffer_try_discard_reserve(), lib_ring_buffer_align_ctx() and
 * lib_ring_buffer_write().
 */
#define LTTNG_UST_RING_BUFFER_CTX_PADDING	24
struct lttng_ust_lib_ring_buffer_ctx {
	/* input received by lib_ring_buffer_reserve(), saved here. */
	struct channel *chan;		/* channel */
	void *priv;			/* client private data */
	struct lttng_ust_shm_handle *handle;	/* shared-memory handle */
	size_t data_size;		/* size of payload */
	int largest_align;		/*
					 * alignment of the largest element
					 * in the payload
					 */
	int cpu;			/* processor id */

	/* output from lib_ring_buffer_reserve() */
	struct lttng_ust_lib_ring_buffer *buf;	/*
					 * buffer corresponding to processor id
					 * for this channel
					 */
	size_t slot_size;		/* size of the reserved slot */
	unsigned long buf_offset;	/* offset following the record header */
	unsigned long pre_offset;	/*
					 * Initial offset position _before_
					 * the record is written. Positioned
					 * prior to record header alignment
					 * padding.
					 */
	uint64_t tsc;			/* time-stamp counter value */
	unsigned int rflags;		/* reservation flags */
	char padding[LTTNG_UST_RING_BUFFER_CTX_PADDING];
};

/**
 * lib_ring_buffer_ctx_init - initialize ring buffer context
 * @ctx: ring buffer context to initialize
 * @chan: channel
 * @priv: client private data
 * @data_size: size of record data payload
 * @largest_align: largest alignment within data payload types
 * @cpu: processor id
 */
static inline
void lib_ring_buffer_ctx_init(struct lttng_ust_lib_ring_buffer_ctx *ctx,
			      struct channel *chan, void *priv,
			      size_t data_size, int largest_align,
			      int cpu, struct lttng_ust_shm_handle *handle)
{
	ctx->chan = chan;
	ctx->priv = priv;
	ctx->data_size = data_size;
	ctx->largest_align = largest_align;
	ctx->cpu = cpu;
	ctx->rflags = 0;
	ctx->handle = handle;
	memset(ctx->padding, 0, LTTNG_UST_RING_BUFFER_CTX_PADDING);
}

/*
 * Reservation flags.
 *
 * RING_BUFFER_RFLAG_FULL_TSC
 *
 * This flag is passed to record_header_size() and to the primitive used to
 * write the record header. It indicates that the full 64-bit time value is
 * needed in the record header. If this flag is not set, the record header needs
 * only to contain "tsc_bits" bit of time value.
 *
 * Reservation flags can be added by the client, starting from
 * "(RING_BUFFER_FLAGS_END << 0)". It can be used to pass information from
 * record_header_size() to lib_ring_buffer_write_record_header().
 */
#define	RING_BUFFER_RFLAG_FULL_TSC		(1U << 0)
#define RING_BUFFER_RFLAG_END			(1U << 1)

/*
 * We need to define RING_BUFFER_ALIGN_ATTR so it is known early at
 * compile-time. We have to duplicate the "config->align" information and the
 * definition here because config->align is used both in the slow and fast
 * paths, but RING_BUFFER_ALIGN_ATTR is only available for the client code.
 */
#ifdef RING_BUFFER_ALIGN

# define RING_BUFFER_ALIGN_ATTR		/* Default arch alignment */

/*
 * Calculate the offset needed to align the type.
 * size_of_type must be non-zero.
 */
static inline
unsigned int lib_ring_buffer_align(size_t align_drift, size_t size_of_type)
{
	return offset_align(align_drift, size_of_type);
}

#else

# define RING_BUFFER_ALIGN_ATTR __attribute__((packed))

/*
 * Calculate the offset needed to align the type.
 * size_of_type must be non-zero.
 */
static inline
unsigned int lib_ring_buffer_align(size_t align_drift, size_t size_of_type)
{
	return 0;
}

#endif

/**
 * lib_ring_buffer_align_ctx - Align context offset on "alignment"
 * @ctx: ring buffer context.
 */
static inline
void lib_ring_buffer_align_ctx(struct lttng_ust_lib_ring_buffer_ctx *ctx,
			   size_t alignment)
{
	ctx->buf_offset += lib_ring_buffer_align(ctx->buf_offset,
						 alignment);
}

/*
 * lib_ring_buffer_check_config() returns 0 on success.
 * Used internally to check for valid configurations at channel creation.
 */
static inline
int lib_ring_buffer_check_config(const struct lttng_ust_lib_ring_buffer_config *config,
			     unsigned int switch_timer_interval,
			     unsigned int read_timer_interval)
{
	if (config->alloc == RING_BUFFER_ALLOC_GLOBAL
	    && config->sync == RING_BUFFER_SYNC_PER_CPU
	    && switch_timer_interval)
		return -EINVAL;
	return 0;
}

#endif /* _LTTNG_RING_BUFFER_CONFIG_H */
Commit	Line	Data
e92f3e28 MD	1	#ifndef _LTTNG_RING_BUFFER_CONFIG_H
e92f3e28 MD	2	#define _LTTNG_RING_BUFFER_CONFIG_H
a6352fd4 MD	3
a6352fd4 MD	4	/*
e92f3e28	5	* lttng/ringbuffer-config.h
a6352fd4 MD	6	*
	7	* Copyright (C) 2010 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
	8	*
	9	* Ring buffer configuration header. Note: after declaring the standard inline
	10	* functions, clients should also include linux/ringbuffer/api.h.
	11	*
e92f3e28 MD	12	* Permission is hereby granted, free of charge, to any person obtaining a copy
	13	* of this software and associated documentation files (the "Software"), to deal
	14	* in the Software without restriction, including without limitation the rights
	15	* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
	16	* copies of the Software, and to permit persons to whom the Software is
	17	* furnished to do so, subject to the following conditions:
a60d70e6	18	*
e92f3e28 MD	19	* The above copyright notice and this permission notice shall be included in
e92f3e28 MD	20	* all copies or substantial portions of the Software.
a6352fd4 MD	21	*/
	22
	23	#include <errno.h>
4318ae1b	24	#include "lttng/ust-tracer.h"
b728d87e MD	25	#include <stdint.h>
	26	#include <stddef.h>
	27	#include <urcu/arch.h>
2e707419	28	#include <string.h>
4318ae1b	29	#include "lttng/align.h"
a6352fd4	30
4cfec15c	31	struct lttng_ust_lib_ring_buffer;
a6352fd4	32	struct channel;
4cfec15c MD	33	struct lttng_ust_lib_ring_buffer_config;
4cfec15c MD	34	struct lttng_ust_lib_ring_buffer_ctx;
38fae1d3	35	struct lttng_ust_shm_handle *handle;
a6352fd4 MD	36
	37	/*
	38	* Ring buffer client callbacks. Only used by slow path, never on fast path.
	39	* For the fast path, record_header_size(), ring_buffer_clock_read() should be
	40	* provided as inline functions too. These may simply return 0 if not used by
	41	* the client.
	42	*/
4cfec15c	43	struct lttng_ust_lib_ring_buffer_client_cb {
a6352fd4 MD	44	/* Mandatory callbacks */
	45
	46	/* A static inline version is also required for fast path */
2fed87ae	47	uint64_t (ring_buffer_clock_read) (struct channel chan);
4cfec15c	48	size_t (record_header_size) (const struct lttng_ust_lib_ring_buffer_config config,
a6352fd4 MD	49	struct channel *chan, size_t offset,
a6352fd4 MD	50	size_t *pre_header_padding,
4cfec15c	51	struct lttng_ust_lib_ring_buffer_ctx *ctx);
a6352fd4 MD	52
	53	/* Slow path only, at subbuffer switch */
	54	size_t (*subbuffer_header_size) (void);
2fed87ae	55	void (buffer_begin) (struct lttng_ust_lib_ring_buffer buf, uint64_t tsc,
1d498196	56	unsigned int subbuf_idx,
38fae1d3	57	struct lttng_ust_shm_handle *handle);
2fed87ae	58	void (buffer_end) (struct lttng_ust_lib_ring_buffer buf, uint64_t tsc,
1d498196	59	unsigned int subbuf_idx, unsigned long data_size,
38fae1d3	60	struct lttng_ust_shm_handle *handle);
a6352fd4 MD	61
	62	/* Optional callbacks (can be set to NULL) */
	63
	64	/* Called at buffer creation/finalize */
4cfec15c	65	int (buffer_create) (struct lttng_ust_lib_ring_buffer buf, void *priv,
1d498196	66	int cpu, const char *name,
38fae1d3	67	struct lttng_ust_shm_handle *handle);
a6352fd4 MD	68	/*
	69	* Clients should guarantee that no new reader handle can be opened
	70	* after finalize.
	71	*/
4cfec15c	72	void (buffer_finalize) (struct lttng_ust_lib_ring_buffer buf,
1d498196	73	void *priv, int cpu,
38fae1d3	74	struct lttng_ust_shm_handle *handle);
a6352fd4 MD	75
	76	/*
	77	* Extract header length, payload length and timestamp from event
	78	* record. Used by buffer iterators. Timestamp is only used by channel
	79	* iterator.
	80	*/
4cfec15c MD	81	void (record_get) (const struct lttng_ust_lib_ring_buffer_config config,
4cfec15c MD	82	struct channel chan, struct lttng_ust_lib_ring_buffer buf,
a6352fd4	83	size_t offset, size_t *header_len,
2fed87ae	84	size_t payload_len, uint64_t timestamp,
38fae1d3	85	struct lttng_ust_shm_handle *handle);
a6352fd4 MD	86	};
	87
	88	/*
	89	* Ring buffer instance configuration.
	90	*
	91	* Declare as "static const" within the client object to ensure the inline fast
	92	* paths can be optimized.
	93	*
	94	* alloc/sync pairs:
	95	*
	96	* RING_BUFFER_ALLOC_PER_CPU and RING_BUFFER_SYNC_PER_CPU :
	97	* Per-cpu buffers with per-cpu synchronization. Tracing must be performed
	98	* with preemption disabled (lib_ring_buffer_get_cpu() and
	99	* lib_ring_buffer_put_cpu()).
	100	*
	101	* RING_BUFFER_ALLOC_PER_CPU and RING_BUFFER_SYNC_GLOBAL :
	102	* Per-cpu buffer with global synchronization. Tracing can be performed with
	103	* preemption enabled, statistically stays on the local buffers.
	104	*
	105	* RING_BUFFER_ALLOC_GLOBAL and RING_BUFFER_SYNC_PER_CPU :
	106	* Should only be used for buffers belonging to a single thread or protected
	107	* by mutual exclusion by the client. Note that periodical sub-buffer switch
	108	* should be disabled in this kind of configuration.
	109	*
	110	* RING_BUFFER_ALLOC_GLOBAL and RING_BUFFER_SYNC_GLOBAL :
	111	* Global shared buffer with global synchronization.
	112	*
	113	* wakeup:
	114	*
	115	* RING_BUFFER_WAKEUP_BY_TIMER uses per-cpu deferrable timers to poll the
	116	* buffers and wake up readers if data is ready. Mainly useful for tracers which
	117	* don't want to call into the wakeup code on the tracing path. Use in
	118	* combination with "read_timer_interval" channel_create() argument.
	119	*
	120	* RING_BUFFER_WAKEUP_BY_WRITER directly wakes up readers when a subbuffer is
	121	* ready to read. Lower latencies before the reader is woken up. Mainly suitable
	122	* for drivers.
	123	*
	124	* RING_BUFFER_WAKEUP_NONE does not perform any wakeup whatsoever. The client
	125	* has the responsibility to perform wakeups.
	126	*/
2e707419	127	#define LTTNG_UST_RING_BUFFER_CONFIG_PADDING 32
4cfec15c	128	struct lttng_ust_lib_ring_buffer_config {
a6352fd4 MD	129	enum {
	130	RING_BUFFER_ALLOC_PER_CPU,
	131	RING_BUFFER_ALLOC_GLOBAL,
	132	} alloc;
	133	enum {
	134	RING_BUFFER_SYNC_PER_CPU, /* Wait-free */
	135	RING_BUFFER_SYNC_GLOBAL, /* Lock-free */
	136	} sync;
	137	enum {
	138	RING_BUFFER_OVERWRITE, /* Overwrite when buffer full */
	139	RING_BUFFER_DISCARD, /* Discard when buffer full */
	140	} mode;
	141	enum {
	142	RING_BUFFER_SPLICE,
	143	RING_BUFFER_MMAP,
	144	RING_BUFFER_READ, /* TODO */
	145	RING_BUFFER_ITERATOR,
	146	RING_BUFFER_NONE,
	147	} output;
	148	enum {
	149	RING_BUFFER_PAGE,
	150	RING_BUFFER_VMAP, /* TODO */
	151	RING_BUFFER_STATIC, /* TODO */
	152	} backend;
	153	enum {
	154	RING_BUFFER_NO_OOPS_CONSISTENCY,
	155	RING_BUFFER_OOPS_CONSISTENCY,
	156	} oops;
	157	enum {
	158	RING_BUFFER_IPI_BARRIER,
	159	RING_BUFFER_NO_IPI_BARRIER,
	160	} ipi;
	161	enum {
	162	RING_BUFFER_WAKEUP_BY_TIMER, /* wake up performed by timer */
	163	RING_BUFFER_WAKEUP_BY_WRITER, /*
	164	* writer wakes up reader,
	165	* not lock-free
	166	* (takes spinlock).
	167	*/
	168	} wakeup;
	169	/*
	170	* tsc_bits: timestamp bits saved at each record.
	171	* 0 and 64 disable the timestamp compression scheme.
	172	*/
	173	unsigned int tsc_bits;
4cfec15c	174	struct lttng_ust_lib_ring_buffer_client_cb cb;
c1fca457 MD	175	/*
	176	* client_type is used by the consumer process (which is in a
	177	* different address space) to lookup the appropriate client
	178	* callbacks and update the cb pointers.
	179	*/
	180	int client_type;
2e707419	181	char padding[LTTNG_UST_RING_BUFFER_CONFIG_PADDING];
a6352fd4 MD	182	};
	183
	184	/*
	185	* ring buffer context
	186	*
	187	* Context passed to lib_ring_buffer_reserve(), lib_ring_buffer_commit(),
	188	* lib_ring_buffer_try_discard_reserve(), lib_ring_buffer_align_ctx() and
	189	* lib_ring_buffer_write().
	190	*/
2e707419	191	#define LTTNG_UST_RING_BUFFER_CTX_PADDING 24
4cfec15c	192	struct lttng_ust_lib_ring_buffer_ctx {
a6352fd4 MD	193	/* input received by lib_ring_buffer_reserve(), saved here. */
	194	struct channel chan; / channel */
	195	void priv; / client private data */
38fae1d3	196	struct lttng_ust_shm_handle handle; / shared-memory handle */
a6352fd4 MD	197	size_t data_size; /* size of payload */
	198	int largest_align; /*
	199	* alignment of the largest element
	200	* in the payload
	201	*/
	202	int cpu; /* processor id */
	203
	204	/* output from lib_ring_buffer_reserve() */
4cfec15c	205	struct lttng_ust_lib_ring_buffer buf; /
a6352fd4 MD	206	* buffer corresponding to processor id
	207	* for this channel
	208	*/
	209	size_t slot_size; /* size of the reserved slot */
	210	unsigned long buf_offset; /* offset following the record header */
	211	unsigned long pre_offset; /*
	212	* Initial offset position _before_
	213	* the record is written. Positioned
	214	* prior to record header alignment
	215	* padding.
	216	*/
2fed87ae	217	uint64_t tsc; /* time-stamp counter value */
a6352fd4	218	unsigned int rflags; /* reservation flags */
2e707419	219	char padding[LTTNG_UST_RING_BUFFER_CTX_PADDING];
a6352fd4 MD	220	};
	221
	222	/**
	223	* lib_ring_buffer_ctx_init - initialize ring buffer context
	224	* @ctx: ring buffer context to initialize
	225	* @chan: channel
	226	* @priv: client private data
	227	* @data_size: size of record data payload
	228	* @largest_align: largest alignment within data payload types
	229	* @cpu: processor id
	230	*/
	231	static inline
4cfec15c	232	void lib_ring_buffer_ctx_init(struct lttng_ust_lib_ring_buffer_ctx *ctx,
a6352fd4 MD	233	struct channel chan, void priv,
a6352fd4 MD	234	size_t data_size, int largest_align,
38fae1d3	235	int cpu, struct lttng_ust_shm_handle *handle)
a6352fd4 MD	236	{
	237	ctx->chan = chan;
	238	ctx->priv = priv;
	239	ctx->data_size = data_size;
	240	ctx->largest_align = largest_align;
	241	ctx->cpu = cpu;
	242	ctx->rflags = 0;
1d498196	243	ctx->handle = handle;
2e707419	244	memset(ctx->padding, 0, LTTNG_UST_RING_BUFFER_CTX_PADDING);
a6352fd4 MD	245	}
	246
	247	/*
	248	* Reservation flags.
	249	*
	250	* RING_BUFFER_RFLAG_FULL_TSC
	251	*
	252	* This flag is passed to record_header_size() and to the primitive used to
	253	* write the record header. It indicates that the full 64-bit time value is
	254	* needed in the record header. If this flag is not set, the record header needs
	255	* only to contain "tsc_bits" bit of time value.
	256	*
	257	* Reservation flags can be added by the client, starting from
	258	* "(RING_BUFFER_FLAGS_END << 0)". It can be used to pass information from
	259	* record_header_size() to lib_ring_buffer_write_record_header().
	260	*/
	261	#define RING_BUFFER_RFLAG_FULL_TSC (1U << 0)
	262	#define RING_BUFFER_RFLAG_END (1U << 1)
	263
	264	/*
	265	* We need to define RING_BUFFER_ALIGN_ATTR so it is known early at
	266	* compile-time. We have to duplicate the "config->align" information and the
	267	* definition here because config->align is used both in the slow and fast
	268	* paths, but RING_BUFFER_ALIGN_ATTR is only available for the client code.
	269	*/
	270	#ifdef RING_BUFFER_ALIGN
	271
	272	# define RING_BUFFER_ALIGN_ATTR /* Default arch alignment */
	273
	274	/*
	275	* Calculate the offset needed to align the type.
	276	* size_of_type must be non-zero.
	277	*/
	278	static inline
	279	unsigned int lib_ring_buffer_align(size_t align_drift, size_t size_of_type)
	280	{
	281	return offset_align(align_drift, size_of_type);
	282	}
	283
	284	#else
	285
	286	# define RING_BUFFER_ALIGN_ATTR __attribute__((packed))
	287
	288	/*
	289	* Calculate the offset needed to align the type.
	290	* size_of_type must be non-zero.
	291	*/
	292	static inline
	293	unsigned int lib_ring_buffer_align(size_t align_drift, size_t size_of_type)
	294	{
	295	return 0;
	296	}
	297
	298	#endif
	299
	300	/**
	301	* lib_ring_buffer_align_ctx - Align context offset on "alignment"
	302	* @ctx: ring buffer context.
	303	*/
	304	static inline
4cfec15c	305	void lib_ring_buffer_align_ctx(struct lttng_ust_lib_ring_buffer_ctx *ctx,
a6352fd4 MD	306	size_t alignment)
	307	{
	308	ctx->buf_offset += lib_ring_buffer_align(ctx->buf_offset,
	309	alignment);
	310	}
	311
	312	/*
	313	* lib_ring_buffer_check_config() returns 0 on success.
	314	* Used internally to check for valid configurations at channel creation.
	315	*/
	316	static inline
4cfec15c	317	int lib_ring_buffer_check_config(const struct lttng_ust_lib_ring_buffer_config *config,
a6352fd4 MD	318	unsigned int switch_timer_interval,
	319	unsigned int read_timer_interval)
	320	{
	321	if (config->alloc == RING_BUFFER_ALLOC_GLOBAL
	322	&& config->sync == RING_BUFFER_SYNC_PER_CPU
	323	&& switch_timer_interval)
	324	return -EINVAL;
	325	return 0;
	326	}
	327
e92f3e28	328	#endif /* _LTTNG_RING_BUFFER_CONFIG_H */