lttng: lib ring buffer clients

Each lttng buffer configuration (discard mode, overwrite mode, mmap
support, splice support, per-cpu buffers, global buffer for metadata) is
a lib ring buffer client.
Signed-off-by: NMathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

drivers/staging/lttng/ltt-ring-buffer-client-discard.c

+/*
+ * ltt-ring-buffer-client-discard.c
+ *
+ * Copyright (C) 2010 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ *
+ * LTTng lib ring buffer client (discard mode).
+ *
+ * Dual LGPL v2.1/GPL v2 license.
+ */
+
+#include <linux/module.h>
+#include "ltt-tracer.h"
+
+#define RING_BUFFER_MODE_TEMPLATE		RING_BUFFER_DISCARD
+#define RING_BUFFER_MODE_TEMPLATE_STRING	"discard"
+#define RING_BUFFER_OUTPUT_TEMPLATE		RING_BUFFER_SPLICE
+#include "ltt-ring-buffer-client.h"
+
+MODULE_LICENSE("GPL and additional rights");
+MODULE_AUTHOR("Mathieu Desnoyers");
+MODULE_DESCRIPTION("LTTng Ring Buffer Client Discard Mode");

drivers/staging/lttng/ltt-ring-buffer-client-mmap-discard.c

+/*
+ * ltt-ring-buffer-client-discard.c
+ *
+ * Copyright (C) 2010 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ *
+ * LTTng lib ring buffer client (discard mode).
+ *
+ * Dual LGPL v2.1/GPL v2 license.
+ */
+
+#include <linux/module.h>
+#include "ltt-tracer.h"
+
+#define RING_BUFFER_MODE_TEMPLATE		RING_BUFFER_DISCARD
+#define RING_BUFFER_MODE_TEMPLATE_STRING	"discard-mmap"
+#define RING_BUFFER_OUTPUT_TEMPLATE		RING_BUFFER_MMAP
+#include "ltt-ring-buffer-client.h"
+
+MODULE_LICENSE("GPL and additional rights");
+MODULE_AUTHOR("Mathieu Desnoyers");
+MODULE_DESCRIPTION("LTTng Ring Buffer Client Discard Mode");

drivers/staging/lttng/ltt-ring-buffer-client-mmap-overwrite.c

+/*
+ * ltt-ring-buffer-client-overwrite.c
+ *
+ * Copyright (C) 2010 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ *
+ * LTTng lib ring buffer client (overwrite mode).
+ *
+ * Dual LGPL v2.1/GPL v2 license.
+ */
+
+#include <linux/module.h>
+#include "ltt-tracer.h"
+
+#define RING_BUFFER_MODE_TEMPLATE		RING_BUFFER_OVERWRITE
+#define RING_BUFFER_MODE_TEMPLATE_STRING	"overwrite-mmap"
+#define RING_BUFFER_OUTPUT_TEMPLATE		RING_BUFFER_MMAP
+#include "ltt-ring-buffer-client.h"
+
+MODULE_LICENSE("GPL and additional rights");
+MODULE_AUTHOR("Mathieu Desnoyers");
+MODULE_DESCRIPTION("LTTng Ring Buffer Client Overwrite Mode");

drivers/staging/lttng/ltt-ring-buffer-client-overwrite.c

+/*
+ * ltt-ring-buffer-client-overwrite.c
+ *
+ * Copyright (C) 2010 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ *
+ * LTTng lib ring buffer client (overwrite mode).
+ *
+ * Dual LGPL v2.1/GPL v2 license.
+ */
+
+#include <linux/module.h>
+#include "ltt-tracer.h"
+
+#define RING_BUFFER_MODE_TEMPLATE		RING_BUFFER_OVERWRITE
+#define RING_BUFFER_MODE_TEMPLATE_STRING	"overwrite"
+#define RING_BUFFER_OUTPUT_TEMPLATE		RING_BUFFER_SPLICE
+#include "ltt-ring-buffer-client.h"
+
+MODULE_LICENSE("GPL and additional rights");
+MODULE_AUTHOR("Mathieu Desnoyers");
+MODULE_DESCRIPTION("LTTng Ring Buffer Client Overwrite Mode");

drivers/staging/lttng/ltt-ring-buffer-client.h

+/*
+ * ltt-ring-buffer-client.h
+ *
+ * Copyright (C) 2010 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ *
+ * LTTng lib ring buffer client template.
+ *
+ * Dual LGPL v2.1/GPL v2 license.
+ */
+
+#include <linux/module.h>
+#include <linux/types.h>
+#include "lib/bitfield.h"
+#include "wrapper/vmalloc.h"	/* for wrapper_vmalloc_sync_all() */
+#include "wrapper/trace-clock.h"
+#include "ltt-events.h"
+#include "ltt-tracer.h"
+#include "wrapper/ringbuffer/frontend_types.h"
+
+/*
+ * Keep the natural field alignment for _each field_ within this structure if
+ * you ever add/remove a field from this header. Packed attribute is not used
+ * because gcc generates poor code on at least powerpc and mips. Don't ever
+ * let gcc add padding between the structure elements.
+ *
+ * The guarantee we have with timestamps is that all the events in a
+ * packet are included (inclusive) within the begin/end timestamps of
+ * the packet. Another guarantee we have is that the "timestamp begin",
+ * as well as the event timestamps, are monotonically increasing (never
+ * decrease) when moving forward in a stream (physically). But this
+ * guarantee does not apply to "timestamp end", because it is sampled at
+ * commit time, which is not ordered with respect to space reservation.
+ */
+
+struct packet_header {
+	/* Trace packet header */
+	uint32_t magic;			/*
+					 * Trace magic number.
+					 * contains endianness information.
+					 */
+	uint8_t uuid[16];
+	uint32_t stream_id;
+
+	struct {
+		/* Stream packet context */
+		uint64_t timestamp_begin;	/* Cycle count at subbuffer start */
+		uint64_t timestamp_end;		/* Cycle count at subbuffer end */
+		uint32_t events_discarded;	/*
+						 * Events lost in this subbuffer since
+						 * the beginning of the trace.
+						 * (may overflow)
+						 */
+		uint32_t content_size;		/* Size of data in subbuffer */
+		uint32_t packet_size;		/* Subbuffer size (include padding) */
+		uint32_t cpu_id;		/* CPU id associated with stream */
+		uint8_t header_end;		/* End of header */
+	} ctx;
+};
+
+
+static inline notrace u64 lib_ring_buffer_clock_read(struct channel *chan)
+{
+	return trace_clock_read64();
+}
+
+static inline
+size_t ctx_get_size(size_t offset, struct lttng_ctx *ctx)
+{
+	int i;
+	size_t orig_offset = offset;
+
+	if (likely(!ctx))
+		return 0;
+	for (i = 0; i < ctx->nr_fields; i++)
+		offset += ctx->fields[i].get_size(offset);
+	return offset - orig_offset;
+}
+
+static inline
+void ctx_record(struct lib_ring_buffer_ctx *bufctx,
+		struct ltt_channel *chan,
+		struct lttng_ctx *ctx)
+{
+	int i;
+
+	if (likely(!ctx))
+		return;
+	for (i = 0; i < ctx->nr_fields; i++)
+		ctx->fields[i].record(&ctx->fields[i], bufctx, chan);
+}
+
+/*
+ * record_header_size - Calculate the header size and padding necessary.
+ * @config: ring buffer instance configuration
+ * @chan: channel
+ * @offset: offset in the write buffer
+ * @pre_header_padding: padding to add before the header (output)
+ * @ctx: reservation context
+ *
+ * Returns the event header size (including padding).
+ *
+ * The payload must itself determine its own alignment from the biggest type it
+ * contains.
+ */
+static __inline__
+unsigned char record_header_size(const struct lib_ring_buffer_config *config,
+				 struct channel *chan, size_t offset,
+				 size_t *pre_header_padding,
+				 struct lib_ring_buffer_ctx *ctx)
+{
+	struct ltt_channel *ltt_chan = channel_get_private(chan);
+	struct ltt_event *event = ctx->priv;
+	size_t orig_offset = offset;
+	size_t padding;
+
+	switch (ltt_chan->header_type) {
+	case 1:	/* compact */
+		padding = lib_ring_buffer_align(offset, ltt_alignof(uint32_t));
+		offset += padding;
+		if (!(ctx->rflags & (RING_BUFFER_RFLAG_FULL_TSC | LTT_RFLAG_EXTENDED))) {
+			offset += sizeof(uint32_t);	/* id and timestamp */
+		} else {
+			/* Minimum space taken by 5-bit id */
+			offset += sizeof(uint8_t);
+			/* Align extended struct on largest member */
+			offset += lib_ring_buffer_align(offset, ltt_alignof(uint64_t));
+			offset += sizeof(uint32_t);	/* id */
+			offset += lib_ring_buffer_align(offset, ltt_alignof(uint64_t));
+			offset += sizeof(uint64_t);	/* timestamp */
+		}
+		break;
+	case 2:	/* large */
+		padding = lib_ring_buffer_align(offset, ltt_alignof(uint16_t));
+		offset += padding;
+		offset += sizeof(uint16_t);
+		if (!(ctx->rflags & (RING_BUFFER_RFLAG_FULL_TSC | LTT_RFLAG_EXTENDED))) {
+			offset += lib_ring_buffer_align(offset, ltt_alignof(uint32_t));
+			offset += sizeof(uint32_t);	/* timestamp */
+		} else {
+			/* Align extended struct on largest member */
+			offset += lib_ring_buffer_align(offset, ltt_alignof(uint64_t));
+			offset += sizeof(uint32_t);	/* id */
+			offset += lib_ring_buffer_align(offset, ltt_alignof(uint64_t));
+			offset += sizeof(uint64_t);	/* timestamp */
+		}
+		break;
+	default:
+		padding = 0;
+		WARN_ON_ONCE(1);
+	}
+	offset += ctx_get_size(offset, event->ctx);
+	offset += ctx_get_size(offset, ltt_chan->ctx);
+
+	*pre_header_padding = padding;
+	return offset - orig_offset;
+}
+
+#include "wrapper/ringbuffer/api.h"
+
+static
+void ltt_write_event_header_slow(const struct lib_ring_buffer_config *config,
+				 struct lib_ring_buffer_ctx *ctx,
+				 uint32_t event_id);
+
+/*
+ * ltt_write_event_header
+ *
+ * Writes the event header to the offset (already aligned on 32-bits).
+ *
+ * @config: ring buffer instance configuration
+ * @ctx: reservation context
+ * @event_id: event ID
+ */
+static __inline__
+void ltt_write_event_header(const struct lib_ring_buffer_config *config,
+			    struct lib_ring_buffer_ctx *ctx,
+			    uint32_t event_id)
+{
+	struct ltt_channel *ltt_chan = channel_get_private(ctx->chan);
+	struct ltt_event *event = ctx->priv;
+
+	if (unlikely(ctx->rflags))
+		goto slow_path;
+
+	switch (ltt_chan->header_type) {
+	case 1:	/* compact */
+	{
+		uint32_t id_time = 0;
+
+		bt_bitfield_write(&id_time, uint32_t, 0, 5, event_id);
+		bt_bitfield_write(&id_time, uint32_t, 5, 27, ctx->tsc);
+		lib_ring_buffer_write(config, ctx, &id_time, sizeof(id_time));
+		break;
+	}
+	case 2:	/* large */
+	{
+		uint32_t timestamp = (uint32_t) ctx->tsc;
+		uint16_t id = event_id;
+
+		lib_ring_buffer_write(config, ctx, &id, sizeof(id));
+		lib_ring_buffer_align_ctx(ctx, ltt_alignof(uint32_t));
+		lib_ring_buffer_write(config, ctx, &timestamp, sizeof(timestamp));
+		break;
+	}
+	default:
+		WARN_ON_ONCE(1);
+	}
+
+	ctx_record(ctx, ltt_chan, ltt_chan->ctx);
+	ctx_record(ctx, ltt_chan, event->ctx);
+	lib_ring_buffer_align_ctx(ctx, ctx->largest_align);
+
+	return;
+
+slow_path:
+	ltt_write_event_header_slow(config, ctx, event_id);
+}
+
+static
+void ltt_write_event_header_slow(const struct lib_ring_buffer_config *config,
+				 struct lib_ring_buffer_ctx *ctx,
+				 uint32_t event_id)
+{
+	struct ltt_channel *ltt_chan = channel_get_private(ctx->chan);
+	struct ltt_event *event = ctx->priv;
+
+	switch (ltt_chan->header_type) {
+	case 1:	/* compact */
+		if (!(ctx->rflags & (RING_BUFFER_RFLAG_FULL_TSC | LTT_RFLAG_EXTENDED))) {
+			uint32_t id_time = 0;
+
+			bt_bitfield_write(&id_time, uint32_t, 0, 5, event_id);
+			bt_bitfield_write(&id_time, uint32_t, 5, 27, ctx->tsc);
+			lib_ring_buffer_write(config, ctx, &id_time, sizeof(id_time));
+		} else {
+			uint8_t id = 0;
+			uint64_t timestamp = ctx->tsc;
+
+			bt_bitfield_write(&id, uint8_t, 0, 5, 31);
+			lib_ring_buffer_write(config, ctx, &id, sizeof(id));
+			/* Align extended struct on largest member */
+			lib_ring_buffer_align_ctx(ctx, ltt_alignof(uint64_t));
+			lib_ring_buffer_write(config, ctx, &event_id, sizeof(event_id));
+			lib_ring_buffer_align_ctx(ctx, ltt_alignof(uint64_t));
+			lib_ring_buffer_write(config, ctx, &timestamp, sizeof(timestamp));
+		}
+		break;
+	case 2:	/* large */
+	{
+		if (!(ctx->rflags & (RING_BUFFER_RFLAG_FULL_TSC | LTT_RFLAG_EXTENDED))) {
+			uint32_t timestamp = (uint32_t) ctx->tsc;
+			uint16_t id = event_id;
+
+			lib_ring_buffer_write(config, ctx, &id, sizeof(id));
+			lib_ring_buffer_align_ctx(ctx, ltt_alignof(uint32_t));
+			lib_ring_buffer_write(config, ctx, &timestamp, sizeof(timestamp));
+		} else {
+			uint16_t id = 65535;
+			uint64_t timestamp = ctx->tsc;
+
+			lib_ring_buffer_write(config, ctx, &id, sizeof(id));
+			/* Align extended struct on largest member */
+			lib_ring_buffer_align_ctx(ctx, ltt_alignof(uint64_t));
+			lib_ring_buffer_write(config, ctx, &event_id, sizeof(event_id));
+			lib_ring_buffer_align_ctx(ctx, ltt_alignof(uint64_t));
+			lib_ring_buffer_write(config, ctx, &timestamp, sizeof(timestamp));
+		}
+		break;
+	}
+	default:
+		WARN_ON_ONCE(1);
+	}
+	ctx_record(ctx, ltt_chan, ltt_chan->ctx);
+	ctx_record(ctx, ltt_chan, event->ctx);
+	lib_ring_buffer_align_ctx(ctx, ctx->largest_align);
+}
+
+static const struct lib_ring_buffer_config client_config;
+
+static u64 client_ring_buffer_clock_read(struct channel *chan)
+{
+	return lib_ring_buffer_clock_read(chan);
+}
+
+static
+size_t client_record_header_size(const struct lib_ring_buffer_config *config,
+				 struct channel *chan, size_t offset,
+				 size_t *pre_header_padding,
+				 struct lib_ring_buffer_ctx *ctx)
+{
+	return record_header_size(config, chan, offset,
+				  pre_header_padding, ctx);
+}
+
+/**
+ * client_packet_header_size - called on buffer-switch to a new sub-buffer
+ *
+ * Return header size without padding after the structure. Don't use packed
+ * structure because gcc generates inefficient code on some architectures
+ * (powerpc, mips..)
+ */
+static size_t client_packet_header_size(void)
+{
+	return offsetof(struct packet_header, ctx.header_end);
+}
+
+static void client_buffer_begin(struct lib_ring_buffer *buf, u64 tsc,
+				unsigned int subbuf_idx)
+{
+	struct channel *chan = buf->backend.chan;
+	struct packet_header *header =
+		(struct packet_header *)
+			lib_ring_buffer_offset_address(&buf->backend,
+				subbuf_idx * chan->backend.subbuf_size);
+	struct ltt_channel *ltt_chan = channel_get_private(chan);
+	struct ltt_session *session = ltt_chan->session;
+
+	header->magic = CTF_MAGIC_NUMBER;
+	memcpy(header->uuid, session->uuid.b, sizeof(session->uuid));
+	header->stream_id = ltt_chan->id;
+	header->ctx.timestamp_begin = tsc;
+	header->ctx.timestamp_end = 0;
+	header->ctx.events_discarded = 0;
+	header->ctx.content_size = 0xFFFFFFFF; /* for debugging */
+	header->ctx.packet_size = 0xFFFFFFFF;
+	header->ctx.cpu_id = buf->backend.cpu;
+}
+
+/*
+ * offset is assumed to never be 0 here : never deliver a completely empty
+ * subbuffer. data_size is between 1 and subbuf_size.
+ */
+static void client_buffer_end(struct lib_ring_buffer *buf, u64 tsc,
+			      unsigned int subbuf_idx, unsigned long data_size)
+{
+	struct channel *chan = buf->backend.chan;
+	struct packet_header *header =
+		(struct packet_header *)
+			lib_ring_buffer_offset_address(&buf->backend,
+				subbuf_idx * chan->backend.subbuf_size);
+	unsigned long records_lost = 0;
+
+	header->ctx.timestamp_end = tsc;
+	header->ctx.content_size = data_size * CHAR_BIT; 	/* in bits */
+	header->ctx.packet_size = PAGE_ALIGN(data_size) * CHAR_BIT; /* in bits */
+	records_lost += lib_ring_buffer_get_records_lost_full(&client_config, buf);
+	records_lost += lib_ring_buffer_get_records_lost_wrap(&client_config, buf);
+	records_lost += lib_ring_buffer_get_records_lost_big(&client_config, buf);
+	header->ctx.events_discarded = records_lost;
+}
+
+static int client_buffer_create(struct lib_ring_buffer *buf, void *priv,
+				int cpu, const char *name)
+{
+	return 0;
+}
+
+static void client_buffer_finalize(struct lib_ring_buffer *buf, void *priv, int cpu)
+{
+}
+
+static const struct lib_ring_buffer_config client_config = {
+	.cb.ring_buffer_clock_read = client_ring_buffer_clock_read,
+	.cb.record_header_size = client_record_header_size,
+	.cb.subbuffer_header_size = client_packet_header_size,
+	.cb.buffer_begin = client_buffer_begin,
+	.cb.buffer_end = client_buffer_end,
+	.cb.buffer_create = client_buffer_create,
+	.cb.buffer_finalize = client_buffer_finalize,
+
+	.tsc_bits = 32,
+	.alloc = RING_BUFFER_ALLOC_PER_CPU,
+	.sync = RING_BUFFER_SYNC_PER_CPU,
+	.mode = RING_BUFFER_MODE_TEMPLATE,
+	.backend = RING_BUFFER_PAGE,
+	.output = RING_BUFFER_OUTPUT_TEMPLATE,
+	.oops = RING_BUFFER_OOPS_CONSISTENCY,
+	.ipi = RING_BUFFER_IPI_BARRIER,
+	.wakeup = RING_BUFFER_WAKEUP_BY_TIMER,
+};
+
+static
+struct channel *_channel_create(const char *name,
+				struct ltt_channel *ltt_chan, void *buf_addr,
+				size_t subbuf_size, size_t num_subbuf,
+				unsigned int switch_timer_interval,
+				unsigned int read_timer_interval)
+{
+	return channel_create(&client_config, name, ltt_chan, buf_addr,
+			      subbuf_size, num_subbuf, switch_timer_interval,
+			      read_timer_interval);
+}
+
+static
+void ltt_channel_destroy(struct channel *chan)
+{
+	channel_destroy(chan);
+}
+
+static
+struct lib_ring_buffer *ltt_buffer_read_open(struct channel *chan)
+{
+	struct lib_ring_buffer *buf;
+	int cpu;
+
+	for_each_channel_cpu(cpu, chan) {
+		buf = channel_get_ring_buffer(&client_config, chan, cpu);
+		if (!lib_ring_buffer_open_read(buf))
+			return buf;
+	}
+	return NULL;
+}
+
+static
+int ltt_buffer_has_read_closed_stream(struct channel *chan)
+{
+	struct lib_ring_buffer *buf;
+	int cpu;
+
+	for_each_channel_cpu(cpu, chan) {
+		buf = channel_get_ring_buffer(&client_config, chan, cpu);
+		if (!atomic_long_read(&buf->active_readers))
+			return 1;
+	}
+	return 0;
+}
+
+static
+void ltt_buffer_read_close(struct lib_ring_buffer *buf)
+{
+	lib_ring_buffer_release_read(buf);
+}
+
+static
+int ltt_event_reserve(struct lib_ring_buffer_ctx *ctx,
+		      uint32_t event_id)
+{
+	struct ltt_channel *ltt_chan = channel_get_private(ctx->chan);
+	int ret, cpu;
+
+	cpu = lib_ring_buffer_get_cpu(&client_config);
+	if (cpu < 0)
+		return -EPERM;
+	ctx->cpu = cpu;
+
+	switch (ltt_chan->header_type) {
+	case 1:	/* compact */
+		if (event_id > 30)
+			ctx->rflags |= LTT_RFLAG_EXTENDED;
+		break;
+	case 2:	/* large */
+		if (event_id > 65534)
+			ctx->rflags |= LTT_RFLAG_EXTENDED;
+		break;
+	default:
+		WARN_ON_ONCE(1);
+	}
+
+	ret = lib_ring_buffer_reserve(&client_config, ctx);
+	if (ret)
+		goto put;
+	ltt_write_event_header(&client_config, ctx, event_id);
+	return 0;
+put:
+	lib_ring_buffer_put_cpu(&client_config);
+	return ret;
+}
+
+static
+void ltt_event_commit(struct lib_ring_buffer_ctx *ctx)
+{
+	lib_ring_buffer_commit(&client_config, ctx);
+	lib_ring_buffer_put_cpu(&client_config);
+}
+
+static
+void ltt_event_write(struct lib_ring_buffer_ctx *ctx, const void *src,
+		     size_t len)
+{
+	lib_ring_buffer_write(&client_config, ctx, src, len);
+}
+
+static
+void ltt_event_write_from_user(struct lib_ring_buffer_ctx *ctx,
+			       const void __user *src, size_t len)
+{
+	lib_ring_buffer_copy_from_user(&client_config, ctx, src, len);
+}
+
+static
+void ltt_event_memset(struct lib_ring_buffer_ctx *ctx,
+		int c, size_t len)
+{
+	lib_ring_buffer_memset(&client_config, ctx, c, len);
+}
+
+static
+wait_queue_head_t *ltt_get_writer_buf_wait_queue(struct channel *chan, int cpu)
+{
+	struct lib_ring_buffer *buf = channel_get_ring_buffer(&client_config,
+					chan, cpu);
+	return &buf->write_wait;
+}
+
+static
+wait_queue_head_t *ltt_get_hp_wait_queue(struct channel *chan)
+{
+	return &chan->hp_wait;
+}
+
+static
+int ltt_is_finalized(struct channel *chan)
+{
+	return lib_ring_buffer_channel_is_finalized(chan);
+}
+
+static
+int ltt_is_disabled(struct channel *chan)
+{
+	return lib_ring_buffer_channel_is_disabled(chan);
+}
+
+static struct ltt_transport ltt_relay_transport = {
+	.name = "relay-" RING_BUFFER_MODE_TEMPLATE_STRING,
+	.owner = THIS_MODULE,
+	.ops = {
+		.channel_create = _channel_create,
+		.channel_destroy = ltt_channel_destroy,
+		.buffer_read_open = ltt_buffer_read_open,
+		.buffer_has_read_closed_stream =
+			ltt_buffer_has_read_closed_stream,
+		.buffer_read_close = ltt_buffer_read_close,
+		.event_reserve = ltt_event_reserve,
+		.event_commit = ltt_event_commit,
+		.event_write = ltt_event_write,
+		.event_write_from_user = ltt_event_write_from_user,
+		.event_memset = ltt_event_memset,
+		.packet_avail_size = NULL,	/* Would be racy anyway */
+		.get_writer_buf_wait_queue = ltt_get_writer_buf_wait_queue,
+		.get_hp_wait_queue = ltt_get_hp_wait_queue,
+		.is_finalized = ltt_is_finalized,
+		.is_disabled = ltt_is_disabled,
+	},
+};
+
+static int __init ltt_ring_buffer_client_init(void)
+{
+	/*
+	 * This vmalloc sync all also takes care of the lib ring buffer
+	 * vmalloc'd module pages when it is built as a module into LTTng.
+	 */
+	wrapper_vmalloc_sync_all();
+	ltt_transport_register(&ltt_relay_transport);
+	return 0;
+}
+
+module_init(ltt_ring_buffer_client_init);
+
+static void __exit ltt_ring_buffer_client_exit(void)
+{
+	ltt_transport_unregister(&ltt_relay_transport);
+}
+
+module_exit(ltt_ring_buffer_client_exit);
+
+MODULE_LICENSE("GPL and additional rights");
+MODULE_AUTHOR("Mathieu Desnoyers");
+MODULE_DESCRIPTION("LTTng ring buffer " RING_BUFFER_MODE_TEMPLATE_STRING
+		   " client");

drivers/staging/lttng/ltt-ring-buffer-metadata-client.c

+/*
+ * ltt-ring-buffer-metadata-client.c
+ *
+ * Copyright (C) 2010 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ *
+ * LTTng lib ring buffer metadta client.
+ *
+ * Dual LGPL v2.1/GPL v2 license.
+ */
+
+#include <linux/module.h>
+#include "ltt-tracer.h"
+
+#define RING_BUFFER_MODE_TEMPLATE		RING_BUFFER_DISCARD
+#define RING_BUFFER_MODE_TEMPLATE_STRING	"metadata"
+#define RING_BUFFER_OUTPUT_TEMPLATE		RING_BUFFER_SPLICE
+#include "ltt-ring-buffer-metadata-client.h"
+
+MODULE_LICENSE("GPL and additional rights");
+MODULE_AUTHOR("Mathieu Desnoyers");
+MODULE_DESCRIPTION("LTTng Ring Buffer Metadata Client");

drivers/staging/lttng/ltt-ring-buffer-metadata-client.h

+/*
+ * ltt-ring-buffer-client.h
+ *
+ * Copyright (C) 2010 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ *
+ * LTTng lib ring buffer client template.
+ *
+ * Dual LGPL v2.1/GPL v2 license.
+ */
+
+#include <linux/module.h>
+#include <linux/types.h>
+#include "wrapper/vmalloc.h"	/* for wrapper_vmalloc_sync_all() */
+#include "ltt-events.h"
+#include "ltt-tracer.h"
+
+struct metadata_packet_header {
+	uint32_t magic;			/* 0x75D11D57 */
+	uint8_t  uuid[16];		/* Unique Universal Identifier */
+	uint32_t checksum;		/* 0 if unused */
+	uint32_t content_size;		/* in bits */
+	uint32_t packet_size;		/* in bits */
+	uint8_t  compression_scheme;	/* 0 if unused */
+	uint8_t  encryption_scheme;	/* 0 if unused */
+	uint8_t  checksum_scheme;	/* 0 if unused */
+	uint8_t  major;			/* CTF spec major version number */
+	uint8_t  minor;			/* CTF spec minor version number */
+	uint8_t  header_end[0];
+};
+
+struct metadata_record_header {
+	uint8_t header_end[0];		/* End of header */
+};
+
+static const struct lib_ring_buffer_config client_config;
+
+static inline
+u64 lib_ring_buffer_clock_read(struct channel *chan)
+{
+	return 0;
+}
+
+static inline
+unsigned char record_header_size(const struct lib_ring_buffer_config *config,
+				 struct channel *chan, size_t offset,
+				 size_t *pre_header_padding,
+				 struct lib_ring_buffer_ctx *ctx)
+{
+	return 0;
+}
+
+#include "wrapper/ringbuffer/api.h"
+
+static u64 client_ring_buffer_clock_read(struct channel *chan)
+{
+	return 0;
+}
+
+static
+size_t client_record_header_size(const struct lib_ring_buffer_config *config,
+				 struct channel *chan, size_t offset,
+				 size_t *pre_header_padding,
+				 struct lib_ring_buffer_ctx *ctx)
+{
+	return 0;
+}
+
+/**
+ * client_packet_header_size - called on buffer-switch to a new sub-buffer
+ *
+ * Return header size without padding after the structure. Don't use packed
+ * structure because gcc generates inefficient code on some architectures
+ * (powerpc, mips..)
+ */
+static size_t client_packet_header_size(void)
+{
+	return offsetof(struct metadata_packet_header, header_end);
+}
+
+static void client_buffer_begin(struct lib_ring_buffer *buf, u64 tsc,
+				unsigned int subbuf_idx)
+{
+	struct channel *chan = buf->backend.chan;
+	struct metadata_packet_header *header =
+		(struct metadata_packet_header *)
+			lib_ring_buffer_offset_address(&buf->backend,
+				subbuf_idx * chan->backend.subbuf_size);
+	struct ltt_channel *ltt_chan = channel_get_private(chan);
+	struct ltt_session *session = ltt_chan->session;
+
+	header->magic = TSDL_MAGIC_NUMBER;
+	memcpy(header->uuid, session->uuid.b, sizeof(session->uuid));
+	header->checksum = 0;		/* 0 if unused */
+	header->content_size = 0xFFFFFFFF; /* in bits, for debugging */
+	header->packet_size = 0xFFFFFFFF;  /* in bits, for debugging */
+	header->compression_scheme = 0;	/* 0 if unused */
+	header->encryption_scheme = 0;	/* 0 if unused */
+	header->checksum_scheme = 0;	/* 0 if unused */
+	header->major = CTF_SPEC_MAJOR;
+	header->minor = CTF_SPEC_MINOR;
+}
+
+/*
+ * offset is assumed to never be 0 here : never deliver a completely empty
+ * subbuffer. data_size is between 1 and subbuf_size.
+ */
+static void client_buffer_end(struct lib_ring_buffer *buf, u64 tsc,
+			      unsigned int subbuf_idx, unsigned long data_size)
+{
+	struct channel *chan = buf->backend.chan;
+	struct metadata_packet_header *header =
+		(struct metadata_packet_header *)
+			lib_ring_buffer_offset_address(&buf->backend,
+				subbuf_idx * chan->backend.subbuf_size);
+	unsigned long records_lost = 0;
+
+	header->content_size = data_size * CHAR_BIT;		/* in bits */
+	header->packet_size = PAGE_ALIGN(data_size) * CHAR_BIT; /* in bits */
+	/*
+	 * We do not care about the records lost count, because the metadata
+	 * channel waits and retry.
+	 */
+	(void) lib_ring_buffer_get_records_lost_full(&client_config, buf);
+	records_lost += lib_ring_buffer_get_records_lost_wrap(&client_config, buf);
+	records_lost += lib_ring_buffer_get_records_lost_big(&client_config, buf);
+	WARN_ON_ONCE(records_lost != 0);
+}
+
+static int client_buffer_create(struct lib_ring_buffer *buf, void *priv,
+				int cpu, const char *name)
+{
+	return 0;
+}
+
+static void client_buffer_finalize(struct lib_ring_buffer *buf, void *priv, int cpu)
+{
+}
+
+static const struct lib_ring_buffer_config client_config = {
+	.cb.ring_buffer_clock_read = client_ring_buffer_clock_read,
+	.cb.record_header_size = client_record_header_size,
+	.cb.subbuffer_header_size = client_packet_header_size,
+	.cb.buffer_begin = client_buffer_begin,
+	.cb.buffer_end = client_buffer_end,
+	.cb.buffer_create = client_buffer_create,
+	.cb.buffer_finalize = client_buffer_finalize,
+
+	.tsc_bits = 0,
+	.alloc = RING_BUFFER_ALLOC_GLOBAL,
+	.sync = RING_BUFFER_SYNC_GLOBAL,
+	.mode = RING_BUFFER_MODE_TEMPLATE,
+	.backend = RING_BUFFER_PAGE,
+	.output = RING_BUFFER_OUTPUT_TEMPLATE,
+	.oops = RING_BUFFER_OOPS_CONSISTENCY,
+	.ipi = RING_BUFFER_IPI_BARRIER,
+	.wakeup = RING_BUFFER_WAKEUP_BY_TIMER,
+};
+
+static
+struct channel *_channel_create(const char *name,
+				struct ltt_channel *ltt_chan, void *buf_addr,
+				size_t subbuf_size, size_t num_subbuf,
+				unsigned int switch_timer_interval,
+				unsigned int read_timer_interval)
+{
+	return channel_create(&client_config, name, ltt_chan, buf_addr,
+			      subbuf_size, num_subbuf, switch_timer_interval,
+			      read_timer_interval);
+}
+
+static
+void ltt_channel_destroy(struct channel *chan)
+{
+	channel_destroy(chan);
+}
+
+static
+struct lib_ring_buffer *ltt_buffer_read_open(struct channel *chan)
+{
+	struct lib_ring_buffer *buf;
+
+	buf = channel_get_ring_buffer(&client_config, chan, 0);
+	if (!lib_ring_buffer_open_read(buf))
+		return buf;
+	return NULL;
+}
+
+static
+int ltt_buffer_has_read_closed_stream(struct channel *chan)
+{
+	struct lib_ring_buffer *buf;
+	int cpu;
+
+	for_each_channel_cpu(cpu, chan) {
+		buf = channel_get_ring_buffer(&client_config, chan, cpu);
+		if (!atomic_long_read(&buf->active_readers))
+			return 1;
+	}
+	return 0;
+}
+
+static
+void ltt_buffer_read_close(struct lib_ring_buffer *buf)
+{
+	lib_ring_buffer_release_read(buf);
+}
+
+static
+int ltt_event_reserve(struct lib_ring_buffer_ctx *ctx, uint32_t event_id)
+{
+	return lib_ring_buffer_reserve(&client_config, ctx);
+}
+
+static
+void ltt_event_commit(struct lib_ring_buffer_ctx *ctx)
+{
+	lib_ring_buffer_commit(&client_config, ctx);
+}
+
+static
+void ltt_event_write(struct lib_ring_buffer_ctx *ctx, const void *src,
+		     size_t len)
+{
+	lib_ring_buffer_write(&client_config, ctx, src, len);
+}
+
+static
+void ltt_event_write_from_user(struct lib_ring_buffer_ctx *ctx,
+			       const void __user *src, size_t len)
+{
+	lib_ring_buffer_copy_from_user(&client_config, ctx, src, len);
+}
+
+static
+void ltt_event_memset(struct lib_ring_buffer_ctx *ctx,
+		int c, size_t len)
+{
+	lib_ring_buffer_memset(&client_config, ctx, c, len);
+}
+
+static
+size_t ltt_packet_avail_size(struct channel *chan)
+			     
+{
+	unsigned long o_begin;
+	struct lib_ring_buffer *buf;
+
+	buf = chan->backend.buf;	/* Only for global buffer ! */
+	o_begin = v_read(&client_config, &buf->offset);
+	if (subbuf_offset(o_begin, chan) != 0) {
+		return chan->backend.subbuf_size - subbuf_offset(o_begin, chan);
+	} else {
+		return chan->backend.subbuf_size - subbuf_offset(o_begin, chan)
+			- sizeof(struct metadata_packet_header);
+	}
+}
+
+static
+wait_queue_head_t *ltt_get_writer_buf_wait_queue(struct channel *chan, int cpu)
+{
+	struct lib_ring_buffer *buf = channel_get_ring_buffer(&client_config,
+					chan, cpu);
+	return &buf->write_wait;
+}
+
+static
+wait_queue_head_t *ltt_get_hp_wait_queue(struct channel *chan)
+{
+	return &chan->hp_wait;
+}
+
+static
+int ltt_is_finalized(struct channel *chan)
+{
+	return lib_ring_buffer_channel_is_finalized(chan);
+}
+
+static
+int ltt_is_disabled(struct channel *chan)
+{
+	return lib_ring_buffer_channel_is_disabled(chan);
+}
+
+static struct ltt_transport ltt_relay_transport = {
+	.name = "relay-" RING_BUFFER_MODE_TEMPLATE_STRING,
+	.owner = THIS_MODULE,
+	.ops = {
+		.channel_create = _channel_create,
+		.channel_destroy = ltt_channel_destroy,
+		.buffer_read_open = ltt_buffer_read_open,
+		.buffer_has_read_closed_stream =
+			ltt_buffer_has_read_closed_stream,
+		.buffer_read_close = ltt_buffer_read_close,
+		.event_reserve = ltt_event_reserve,
+		.event_commit = ltt_event_commit,
+		.event_write_from_user = ltt_event_write_from_user,
+		.event_memset = ltt_event_memset,
+		.event_write = ltt_event_write,
+		.packet_avail_size = ltt_packet_avail_size,
+		.get_writer_buf_wait_queue = ltt_get_writer_buf_wait_queue,
+		.get_hp_wait_queue = ltt_get_hp_wait_queue,
+		.is_finalized = ltt_is_finalized,
+		.is_disabled = ltt_is_disabled,
+	},
+};
+
+static int __init ltt_ring_buffer_client_init(void)
+{
+	/*
+	 * This vmalloc sync all also takes care of the lib ring buffer
+	 * vmalloc'd module pages when it is built as a module into LTTng.
+	 */
+	wrapper_vmalloc_sync_all();
+	ltt_transport_register(&ltt_relay_transport);
+	return 0;
+}
+
+module_init(ltt_ring_buffer_client_init);
+
+static void __exit ltt_ring_buffer_client_exit(void)
+{
+	ltt_transport_unregister(&ltt_relay_transport);
+}
+
+module_exit(ltt_ring_buffer_client_exit);
+
+MODULE_LICENSE("GPL and additional rights");
+MODULE_AUTHOR("Mathieu Desnoyers");
+MODULE_DESCRIPTION("LTTng ring buffer " RING_BUFFER_MODE_TEMPLATE_STRING
+		   " client");

drivers/staging/lttng/ltt-ring-buffer-metadata-mmap-client.c

+/*
+ * ltt-ring-buffer-metadata-client.c
+ *
+ * Copyright (C) 2010 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ *
+ * LTTng lib ring buffer metadta client.
+ *
+ * Dual LGPL v2.1/GPL v2 license.
+ */
+
+#include <linux/module.h>
+#include "ltt-tracer.h"
+
+#define RING_BUFFER_MODE_TEMPLATE		RING_BUFFER_DISCARD
+#define RING_BUFFER_MODE_TEMPLATE_STRING	"metadata-mmap"
+#define RING_BUFFER_OUTPUT_TEMPLATE		RING_BUFFER_MMAP
+#include "ltt-ring-buffer-metadata-client.h"
+
+MODULE_LICENSE("GPL and additional rights");
+MODULE_AUTHOR("Mathieu Desnoyers");
+MODULE_DESCRIPTION("LTTng Ring Buffer Metadata Client");