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

/* SPDX-License-Identifier: (GPL-2.0-only OR LGPL-2.1-only)
 *
 * ringbuffer/config.h
 *
 * Ring buffer configuration header. Note: after declaring the standard inline
 * functions, clients should also include linux/ringbuffer/api.h.
 *
 * Copyright (C) 2010-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
 */

#ifndef _LIB_RING_BUFFER_CONFIG_H
#define _LIB_RING_BUFFER_CONFIG_H

#include <linux/types.h>
#include <linux/percpu.h>
#include <lttng/align.h>
#include <lttng/tracer-core.h>

struct lib_ring_buffer;
struct lttng_kernel_ring_buffer_channel;
struct lib_ring_buffer_config;
struct lttng_kernel_ring_buffer_ctx;
struct lttng_kernel_ring_buffer_ctx_private;

/*
 * 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 lib_ring_buffer_client_cb {
	/* Mandatory callbacks */

	/* A static inline version is also required for fast path */
	u64 (*ring_buffer_clock_read) (struct lttng_kernel_ring_buffer_channel *chan);
	size_t (*record_header_size) (const struct lib_ring_buffer_config *config,
				      struct lttng_kernel_ring_buffer_channel *chan, size_t offset,
				      size_t *pre_header_padding,
				      struct lttng_kernel_ring_buffer_ctx *ctx,
				      void *client_ctx);

	/* Slow path only, at subbuffer switch */
	size_t (*subbuffer_header_size) (void);
	void (*buffer_begin) (struct lib_ring_buffer *buf, u64 tsc,
			      unsigned int subbuf_idx);
	void (*buffer_end) (struct lib_ring_buffer *buf, u64 tsc,
			    unsigned int subbuf_idx, unsigned long data_size);

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

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

	/*
	 * 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 lib_ring_buffer_config *config,
			    struct lttng_kernel_ring_buffer_channel *chan, struct lib_ring_buffer *buf,
			    size_t offset, size_t *header_len,
			    size_t *payload_len, u64 *timestamp);
};

/*
 * 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 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. Going through an "irq_work" allows triggering this type of wakeup
 * even from NMI context: the wakeup will be slightly delayed until the next
 * interrupts are handled.
 *
 * RING_BUFFER_WAKEUP_NONE does not perform any wakeup whatsoever. The client
 * has the responsibility to perform wakeups.
 */
struct 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 through
						 * irq_work.
						 */
	} wakeup;
	/*
	 * tsc_bits: timestamp bits saved at each record.
	 *   0 and 64 disable the timestamp compression scheme.
	 */
	unsigned int tsc_bits;
	struct lib_ring_buffer_client_cb cb;
};

/*
 * ring buffer private context
 *
 * Private 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().
 *
 * Get struct lttng_kernel_ring_buffer_ctx parent with container_of().
 */

struct lttng_kernel_ring_buffer_ctx_private {
	/* input received by lib_ring_buffer_reserve(). */
	struct lttng_kernel_ring_buffer_channel *chan;			/* ring buffer channel */

	/* output from lib_ring_buffer_reserve() */
	int reserve_cpu;			/* processor id updated by the reserve */
	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.
						 */
	u64 tsc;				/* time-stamp counter value */
	unsigned int rflags;			/* reservation flags */

	struct lib_ring_buffer *buf;		/*
						 * buffer corresponding to processor id
						 * for this channel
						 */
	struct lib_ring_buffer_backend_pages *backend_pages;
};

/*
 * 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().
 */
struct lttng_kernel_ring_buffer_ctx {
	/* Private ring buffer context, set by reserve callback. */
	struct lttng_kernel_ring_buffer_ctx_private priv;

	/* input received by lib_ring_buffer_reserve(), saved here. */
	void *client_priv;		/* Ring buffer client private data */

	size_t data_size;		/* size of payload */
	int largest_align;		/*
					 * alignment of the largest element
					 * in the payload
					 */
	struct lttng_kernel_probe_ctx *probe_ctx;	/* Probe context */
};

/**
 * lib_ring_buffer_ctx_init - initialize ring buffer context
 * @ctx: ring buffer context to initialize
 * @client_priv: client private data
 * @data_size: size of record data payload. It must be greater than 0.
 * @largest_align: largest alignment within data payload types
 */
static inline
void lib_ring_buffer_ctx_init(struct lttng_kernel_ring_buffer_ctx *ctx,
			      void *client_priv,
			      size_t data_size, int largest_align,
			      struct lttng_kernel_probe_ctx *probe_ctx)
{
	ctx->client_priv = client_priv;
	ctx->data_size = data_size;
	ctx->largest_align = largest_align;
	ctx->probe_ctx = probe_ctx;
}

/*
 * 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)

#ifndef LTTNG_TRACER_CORE_H
#error "lttng/tracer-core.h is needed for RING_BUFFER_ALIGN define"
#endif

/*
 * 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_kernel_ring_buffer_ctx *ctx,
			   size_t alignment)
{
	ctx->priv.buf_offset += lib_ring_buffer_align(ctx->priv.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 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;
}

#include <ringbuffer/vatomic.h>

#endif /* _LIB_RING_BUFFER_CONFIG_H */
Commit	Line	Data
b7cdc182	1	/* SPDX-License-Identifier: (GPL-2.0-only OR LGPL-2.1-only)
9f36eaed	2	*
24591303	3	* ringbuffer/config.h
f3bc08c5 MD	4	*
	5	* Ring buffer configuration header. Note: after declaring the standard inline
	6	* functions, clients should also include linux/ringbuffer/api.h.
	7	*
886d51a3	8	* Copyright (C) 2010-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
f3bc08c5 MD	9	*/
f3bc08c5 MD	10
9f36eaed MJ	11	#ifndef _LIB_RING_BUFFER_CONFIG_H
	12	#define _LIB_RING_BUFFER_CONFIG_H
	13
f3bc08c5 MD	14	#include <linux/types.h>
f3bc08c5 MD	15	#include <linux/percpu.h>
a071f25d	16	#include <lttng/align.h>
2df37e95	17	#include <lttng/tracer-core.h>
f3bc08c5 MD	18
f3bc08c5 MD	19	struct lib_ring_buffer;
860c213b	20	struct lttng_kernel_ring_buffer_channel;
f3bc08c5	21	struct lib_ring_buffer_config;
8a57ec02	22	struct lttng_kernel_ring_buffer_ctx;
b1199bd3	23	struct lttng_kernel_ring_buffer_ctx_private;
f3bc08c5 MD	24
	25	/*
	26	* Ring buffer client callbacks. Only used by slow path, never on fast path.
	27	* For the fast path, record_header_size(), ring_buffer_clock_read() should be
	28	* provided as inline functions too. These may simply return 0 if not used by
	29	* the client.
	30	*/
	31	struct lib_ring_buffer_client_cb {
	32	/* Mandatory callbacks */
	33
	34	/* A static inline version is also required for fast path */
860c213b	35	u64 (ring_buffer_clock_read) (struct lttng_kernel_ring_buffer_channel chan);
f3bc08c5	36	size_t (record_header_size) (const struct lib_ring_buffer_config config,
860c213b	37	struct lttng_kernel_ring_buffer_channel *chan, size_t offset,
f3bc08c5	38	size_t *pre_header_padding,
8a57ec02	39	struct lttng_kernel_ring_buffer_ctx *ctx,
cc62f29e	40	void *client_ctx);
f3bc08c5 MD	41
	42	/* Slow path only, at subbuffer switch */
	43	size_t (*subbuffer_header_size) (void);
	44	void (buffer_begin) (struct lib_ring_buffer buf, u64 tsc,
	45	unsigned int subbuf_idx);
	46	void (buffer_end) (struct lib_ring_buffer buf, u64 tsc,
	47	unsigned int subbuf_idx, unsigned long data_size);
	48
	49	/* Optional callbacks (can be set to NULL) */
	50
	51	/* Called at buffer creation/finalize */
	52	int (buffer_create) (struct lib_ring_buffer buf, void *priv,
	53	int cpu, const char *name);
	54	/*
	55	* Clients should guarantee that no new reader handle can be opened
	56	* after finalize.
	57	*/
	58	void (buffer_finalize) (struct lib_ring_buffer buf, void *priv, int cpu);
	59
	60	/*
	61	* Extract header length, payload length and timestamp from event
	62	* record. Used by buffer iterators. Timestamp is only used by channel
	63	* iterator.
	64	*/
	65	void (record_get) (const struct lib_ring_buffer_config config,
860c213b	66	struct lttng_kernel_ring_buffer_channel chan, struct lib_ring_buffer buf,
f3bc08c5 MD	67	size_t offset, size_t *header_len,
	68	size_t payload_len, u64 timestamp);
	69	};
	70
	71	/*
	72	* Ring buffer instance configuration.
	73	*
	74	* Declare as "static const" within the client object to ensure the inline fast
	75	* paths can be optimized.
	76	*
	77	* alloc/sync pairs:
	78	*
	79	* RING_BUFFER_ALLOC_PER_CPU and RING_BUFFER_SYNC_PER_CPU :
	80	* Per-cpu buffers with per-cpu synchronization. Tracing must be performed
	81	* with preemption disabled (lib_ring_buffer_get_cpu() and
	82	* lib_ring_buffer_put_cpu()).
	83	*
	84	* RING_BUFFER_ALLOC_PER_CPU and RING_BUFFER_SYNC_GLOBAL :
	85	* Per-cpu buffer with global synchronization. Tracing can be performed with
	86	* preemption enabled, statistically stays on the local buffers.
	87	*
	88	* RING_BUFFER_ALLOC_GLOBAL and RING_BUFFER_SYNC_PER_CPU :
	89	* Should only be used for buffers belonging to a single thread or protected
	90	* by mutual exclusion by the client. Note that periodical sub-buffer switch
	91	* should be disabled in this kind of configuration.
	92	*
	93	* RING_BUFFER_ALLOC_GLOBAL and RING_BUFFER_SYNC_GLOBAL :
	94	* Global shared buffer with global synchronization.
	95	*
	96	* wakeup:
	97	*
da9f3fb7	98	* RING_BUFFER_WAKEUP_BY_TIMER uses per-cpu timers to poll the
f3bc08c5 MD	99	* buffers and wake up readers if data is ready. Mainly useful for tracers which
	100	* don't want to call into the wakeup code on the tracing path. Use in
	101	* combination with "read_timer_interval" channel_create() argument.
	102	*
	103	* RING_BUFFER_WAKEUP_BY_WRITER directly wakes up readers when a subbuffer is
	104	* ready to read. Lower latencies before the reader is woken up. Mainly suitable
fbd4d558 MD	105	* for drivers. Going through an "irq_work" allows triggering this type of wakeup
	106	* even from NMI context: the wakeup will be slightly delayed until the next
	107	* interrupts are handled.
f3bc08c5 MD	108	*
	109	* RING_BUFFER_WAKEUP_NONE does not perform any wakeup whatsoever. The client
	110	* has the responsibility to perform wakeups.
	111	*/
	112	struct lib_ring_buffer_config {
	113	enum {
	114	RING_BUFFER_ALLOC_PER_CPU,
	115	RING_BUFFER_ALLOC_GLOBAL,
	116	} alloc;
	117	enum {
	118	RING_BUFFER_SYNC_PER_CPU, /* Wait-free */
	119	RING_BUFFER_SYNC_GLOBAL, /* Lock-free */
	120	} sync;
	121	enum {
	122	RING_BUFFER_OVERWRITE, /* Overwrite when buffer full */
	123	RING_BUFFER_DISCARD, /* Discard when buffer full */
	124	} mode;
	125	enum {
	126	RING_BUFFER_SPLICE,
	127	RING_BUFFER_MMAP,
	128	RING_BUFFER_READ, /* TODO */
	129	RING_BUFFER_ITERATOR,
	130	RING_BUFFER_NONE,
	131	} output;
	132	enum {
	133	RING_BUFFER_PAGE,
	134	RING_BUFFER_VMAP, /* TODO */
	135	RING_BUFFER_STATIC, /* TODO */
	136	} backend;
	137	enum {
	138	RING_BUFFER_NO_OOPS_CONSISTENCY,
	139	RING_BUFFER_OOPS_CONSISTENCY,
	140	} oops;
	141	enum {
	142	RING_BUFFER_IPI_BARRIER,
	143	RING_BUFFER_NO_IPI_BARRIER,
	144	} ipi;
	145	enum {
	146	RING_BUFFER_WAKEUP_BY_TIMER, /* wake up performed by timer */
	147	RING_BUFFER_WAKEUP_BY_WRITER, /*
fbd4d558 MD	148	* writer wakes up reader through
fbd4d558 MD	149	* irq_work.
f3bc08c5 MD	150	*/
	151	} wakeup;
	152	/*
	153	* tsc_bits: timestamp bits saved at each record.
	154	* 0 and 64 disable the timestamp compression scheme.
	155	*/
	156	unsigned int tsc_bits;
	157	struct lib_ring_buffer_client_cb cb;
	158	};
	159
b1199bd3 MD	160	/*
	161	* ring buffer private context
	162	*
	163	* Private context passed to lib_ring_buffer_reserve(), lib_ring_buffer_commit(),
	164	* lib_ring_buffer_try_discard_reserve(), lib_ring_buffer_align_ctx() and
	165	* lib_ring_buffer_write().
	166	*
	167	* Get struct lttng_kernel_ring_buffer_ctx parent with container_of().
	168	*/
	169
	170	struct lttng_kernel_ring_buffer_ctx_private {
	171	/* input received by lib_ring_buffer_reserve(). */
860c213b	172	struct lttng_kernel_ring_buffer_channel chan; / ring buffer channel */
b1199bd3 MD	173
	174	/* output from lib_ring_buffer_reserve() */
	175	int reserve_cpu; /* processor id updated by the reserve */
	176	size_t slot_size; /* size of the reserved slot */
	177	unsigned long buf_offset; /* offset following the record header */
	178	unsigned long pre_offset; /*
	179	* Initial offset position _before_
	180	* the record is written. Positioned
	181	* prior to record header alignment
	182	* padding.
	183	*/
	184	u64 tsc; /* time-stamp counter value */
	185	unsigned int rflags; /* reservation flags */
	186
	187	struct lib_ring_buffer buf; /
	188	* buffer corresponding to processor id
	189	* for this channel
	190	*/
	191	struct lib_ring_buffer_backend_pages *backend_pages;
	192	};
	193
f3bc08c5 MD	194	/*
	195	* ring buffer context
	196	*
	197	* Context passed to lib_ring_buffer_reserve(), lib_ring_buffer_commit(),
	198	* lib_ring_buffer_try_discard_reserve(), lib_ring_buffer_align_ctx() and
	199	* lib_ring_buffer_write().
	200	*/
8a57ec02	201	struct lttng_kernel_ring_buffer_ctx {
b1199bd3 MD	202	/* Private ring buffer context, set by reserve callback. */
	203	struct lttng_kernel_ring_buffer_ctx_private priv;
	204
f3bc08c5	205	/* input received by lib_ring_buffer_reserve(), saved here. */
b1199bd3 MD	206	void client_priv; / Ring buffer client private data */
b1199bd3 MD	207
f3bc08c5 MD	208	size_t data_size; /* size of payload */
	209	int largest_align; /*
	210	* alignment of the largest element
	211	* in the payload
	212	*/
a92e844e	213	struct lttng_kernel_probe_ctx probe_ctx; / Probe context */
f3bc08c5 MD	214	};
	215
	216	/**
	217	* lib_ring_buffer_ctx_init - initialize ring buffer context
	218	* @ctx: ring buffer context to initialize
b1199bd3	219	* @client_priv: client private data
3cae7f22	220	* @data_size: size of record data payload. It must be greater than 0.
f3bc08c5	221	* @largest_align: largest alignment within data payload types
f3bc08c5 MD	222	*/
f3bc08c5 MD	223	static inline
8a57ec02	224	void lib_ring_buffer_ctx_init(struct lttng_kernel_ring_buffer_ctx *ctx,
b1199bd3	225	void *client_priv,
f3bc08c5	226	size_t data_size, int largest_align,
a92e844e	227	struct lttng_kernel_probe_ctx *probe_ctx)
f3bc08c5	228	{
b1199bd3	229	ctx->client_priv = client_priv;
f3bc08c5 MD	230	ctx->data_size = data_size;
f3bc08c5 MD	231	ctx->largest_align = largest_align;
b1199bd3	232	ctx->probe_ctx = probe_ctx;
f3bc08c5 MD	233	}
	234
	235	/*
	236	* Reservation flags.
	237	*
	238	* RING_BUFFER_RFLAG_FULL_TSC
	239	*
	240	* This flag is passed to record_header_size() and to the primitive used to
	241	* write the record header. It indicates that the full 64-bit time value is
	242	* needed in the record header. If this flag is not set, the record header needs
	243	* only to contain "tsc_bits" bit of time value.
	244	*
	245	* Reservation flags can be added by the client, starting from
	246	* "(RING_BUFFER_FLAGS_END << 0)". It can be used to pass information from
	247	* record_header_size() to lib_ring_buffer_write_record_header().
	248	*/
	249	#define RING_BUFFER_RFLAG_FULL_TSC (1U << 0)
	250	#define RING_BUFFER_RFLAG_END (1U << 1)
	251
ae090dc5	252	#ifndef LTTNG_TRACER_CORE_H
2df37e95	253	#error "lttng/tracer-core.h is needed for RING_BUFFER_ALIGN define"
ae090dc5 MD	254	#endif
ae090dc5 MD	255
f3bc08c5 MD	256	/*
	257	* We need to define RING_BUFFER_ALIGN_ATTR so it is known early at
	258	* compile-time. We have to duplicate the "config->align" information and the
	259	* definition here because config->align is used both in the slow and fast
	260	* paths, but RING_BUFFER_ALIGN_ATTR is only available for the client code.
	261	*/
	262	#ifdef RING_BUFFER_ALIGN
	263
	264	# define RING_BUFFER_ALIGN_ATTR /* Default arch alignment */
	265
	266	/*
	267	* Calculate the offset needed to align the type.
	268	* size_of_type must be non-zero.
	269	*/
	270	static inline
	271	unsigned int lib_ring_buffer_align(size_t align_drift, size_t size_of_type)
	272	{
	273	return offset_align(align_drift, size_of_type);
	274	}
	275
	276	#else
	277
	278	# define RING_BUFFER_ALIGN_ATTR __attribute__((packed))
	279
	280	/*
	281	* Calculate the offset needed to align the type.
	282	* size_of_type must be non-zero.
	283	*/
	284	static inline
	285	unsigned int lib_ring_buffer_align(size_t align_drift, size_t size_of_type)
	286	{
	287	return 0;
	288	}
	289
	290	#endif
	291
	292	/**
	293	* lib_ring_buffer_align_ctx - Align context offset on "alignment"
	294	* @ctx: ring buffer context.
	295	*/
	296	static inline
8a57ec02	297	void lib_ring_buffer_align_ctx(struct lttng_kernel_ring_buffer_ctx *ctx,
f3bc08c5 MD	298	size_t alignment)
f3bc08c5 MD	299	{
b1199bd3	300	ctx->priv.buf_offset += lib_ring_buffer_align(ctx->priv.buf_offset,
f3bc08c5 MD	301	alignment);
	302	}
	303
	304	/*
	305	* lib_ring_buffer_check_config() returns 0 on success.
	306	* Used internally to check for valid configurations at channel creation.
	307	*/
	308	static inline
	309	int lib_ring_buffer_check_config(const struct lib_ring_buffer_config *config,
	310	unsigned int switch_timer_interval,
	311	unsigned int read_timer_interval)
	312	{
	313	if (config->alloc == RING_BUFFER_ALLOC_GLOBAL
	314	&& config->sync == RING_BUFFER_SYNC_PER_CPU
	315	&& switch_timer_interval)
	316	return -EINVAL;
	317	return 0;
	318	}
	319
24591303	320	#include <ringbuffer/vatomic.h>
f3bc08c5	321
886d51a3	322	#endif /* _LIB_RING_BUFFER_CONFIG_H */