liblttng-ust/lttng-ring-buffer-client.h

   1 /*
   2  * lttng-ring-buffer-client.h
   3  *
   4  * LTTng lib ring buffer client template.
   5  *
   6  * Copyright (C) 2010-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   7  *
   8  * This library is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU Lesser General Public
  10  * License as published by the Free Software Foundation; only
  11  * version 2.1 of the License.
  12  *
  13  * This library is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  16  * Lesser General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU Lesser General Public
  19  * License along with this library; if not, write to the Free Software
  20  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  21  */
  22
  23 #include <stdint.h>
  24 #include <lttng/ust-events.h>
  25 #include "lttng/bitfield.h"
  26 #include "clock.h"
  27 #include "lttng-tracer.h"
  28 #include "../libringbuffer/frontend_types.h"
  29
  30 #define LTTNG_COMPACT_EVENT_BITS       5
  31 #define LTTNG_COMPACT_TSC_BITS         27
  32
  33 /*
  34  * Keep the natural field alignment for _each field_ within this structure if
  35  * you ever add/remove a field from this header. Packed attribute is not used
  36  * because gcc generates poor code on at least powerpc and mips. Don't ever
  37  * let gcc add padding between the structure elements.
  38  */
  39
  40 struct packet_header {
  41         /* Trace packet header */
  42         uint32_t magic;                 /*
  43                                          * Trace magic number.
  44                                          * contains endianness information.
  45                                          */
  46         uint8_t uuid[LTTNG_UST_UUID_LEN];
  47         uint32_t stream_id;
  48         uint64_t stream_instance_id;
  49
  50         struct {
  51                 /* Stream packet context */
  52                 uint64_t timestamp_begin;       /* Cycle count at subbuffer start */
  53                 uint64_t timestamp_end;         /* Cycle count at subbuffer end */
  54                 uint64_t content_size;          /* Size of data in subbuffer */
  55                 uint64_t packet_size;           /* Subbuffer size (include padding) */
  56                 unsigned long events_discarded; /*
  57                                                  * Events lost in this subbuffer since
  58                                                  * the beginning of the trace.
  59                                                  * (may overflow)
  60                                                  */
  61                 uint32_t cpu_id;                /* CPU id associated with stream */
  62                 uint8_t header_end;             /* End of header */
  63         } ctx;
  64 };
  65
  66
  67 static inline uint64_t lib_ring_buffer_clock_read(struct channel *chan)
  68 {
  69         return trace_clock_read64();
  70 }
  71
  72 static inline
  73 size_t ctx_get_size(size_t offset, struct lttng_ctx *ctx)
  74 {
  75         int i;
  76         size_t orig_offset = offset;
  77
  78         if (caa_likely(!ctx))
  79                 return 0;
  80         offset += lib_ring_buffer_align(offset, ctx->largest_align);
  81         for (i = 0; i < ctx->nr_fields; i++)
  82                 offset += ctx->fields[i].get_size(&ctx->fields[i], offset);
  83         return offset - orig_offset;
  84 }
  85
  86 static inline
  87 void ctx_record(struct lttng_ust_lib_ring_buffer_ctx *bufctx,
  88                 struct lttng_channel *chan,
  89                 struct lttng_ctx *ctx)
  90 {
  91         int i;
  92
  93         if (caa_likely(!ctx))
  94                 return;
  95         lib_ring_buffer_align_ctx(bufctx, ctx->largest_align);
  96         for (i = 0; i < ctx->nr_fields; i++)
  97                 ctx->fields[i].record(&ctx->fields[i], bufctx, chan);
  98 }
  99
 100 /*
 101  * record_header_size - Calculate the header size and padding necessary.
 102  * @config: ring buffer instance configuration
 103  * @chan: channel
 104  * @offset: offset in the write buffer
 105  * @pre_header_padding: padding to add before the header (output)
 106  * @ctx: reservation context
 107  *
 108  * Returns the event header size (including padding).
 109  *
 110  * The payload must itself determine its own alignment from the biggest type it
 111  * contains.
 112  */
 113 static __inline__
 114 size_t record_header_size(const struct lttng_ust_lib_ring_buffer_config *config,
 115                                  struct channel *chan, size_t offset,
 116                                  size_t *pre_header_padding,
 117                                  struct lttng_ust_lib_ring_buffer_ctx *ctx)
 118 {
 119         struct lttng_channel *lttng_chan = channel_get_private(chan);
 120         struct lttng_event *event = ctx->priv;
 121         size_t orig_offset = offset;
 122         size_t padding;
 123
 124         switch (lttng_chan->header_type) {
 125         case 1: /* compact */
 126                 padding = lib_ring_buffer_align(offset, lttng_alignof(uint32_t));
 127                 offset += padding;
 128                 if (!(ctx->rflags & (RING_BUFFER_RFLAG_FULL_TSC | LTTNG_RFLAG_EXTENDED))) {
 129                         offset += sizeof(uint32_t);     /* id and timestamp */
 130                 } else {
 131                         /* Minimum space taken by LTTNG_COMPACT_EVENT_BITS id */
 132                         offset += (LTTNG_COMPACT_EVENT_BITS + CHAR_BIT - 1) / CHAR_BIT;
 133                         /* Align extended struct on largest member */
 134                         offset += lib_ring_buffer_align(offset, lttng_alignof(uint64_t));
 135                         offset += sizeof(uint32_t);     /* id */
 136                         offset += lib_ring_buffer_align(offset, lttng_alignof(uint64_t));
 137                         offset += sizeof(uint64_t);     /* timestamp */
 138                 }
 139                 break;
 140         case 2: /* large */
 141                 padding = lib_ring_buffer_align(offset, lttng_alignof(uint16_t));
 142                 offset += padding;
 143                 offset += sizeof(uint16_t);
 144                 if (!(ctx->rflags & (RING_BUFFER_RFLAG_FULL_TSC | LTTNG_RFLAG_EXTENDED))) {
 145                         offset += lib_ring_buffer_align(offset, lttng_alignof(uint32_t));
 146                         offset += sizeof(uint32_t);     /* timestamp */
 147                 } else {
 148                         /* Align extended struct on largest member */
 149                         offset += lib_ring_buffer_align(offset, lttng_alignof(uint64_t));
 150                         offset += sizeof(uint32_t);     /* id */
 151                         offset += lib_ring_buffer_align(offset, lttng_alignof(uint64_t));
 152                         offset += sizeof(uint64_t);     /* timestamp */
 153                 }
 154                 break;
 155         default:
 156                 padding = 0;
 157                 WARN_ON_ONCE(1);
 158         }
 159         offset += ctx_get_size(offset, event->ctx);
 160         offset += ctx_get_size(offset, lttng_chan->ctx);
 161
 162         *pre_header_padding = padding;
 163         return offset - orig_offset;
 164 }
 165
 166 #include "../libringbuffer/api.h"
 167 #include "lttng-rb-clients.h"
 168
 169 static
 170 void lttng_write_event_header_slow(const struct lttng_ust_lib_ring_buffer_config *config,
 171                                  struct lttng_ust_lib_ring_buffer_ctx *ctx,
 172                                  uint32_t event_id);
 173
 174 /*
 175  * lttng_write_event_header
 176  *
 177  * Writes the event header to the offset (already aligned on 32-bits).
 178  *
 179  * @config: ring buffer instance configuration
 180  * @ctx: reservation context
 181  * @event_id: event ID
 182  */
 183 static __inline__
 184 void lttng_write_event_header(const struct lttng_ust_lib_ring_buffer_config *config,
 185                             struct lttng_ust_lib_ring_buffer_ctx *ctx,
 186                             uint32_t event_id)
 187 {
 188         struct lttng_channel *lttng_chan = channel_get_private(ctx->chan);
 189         struct lttng_stack_ctx *lttng_ctx = ctx->priv2;
 190
 191         if (caa_unlikely(ctx->rflags))
 192                 goto slow_path;
 193
 194         switch (lttng_chan->header_type) {
 195         case 1: /* compact */
 196         {
 197                 uint32_t id_time = 0;
 198
 199                 bt_bitfield_write(&id_time, uint32_t,
 200                                 0,
 201                                 LTTNG_COMPACT_EVENT_BITS,
 202                                 event_id);
 203                 bt_bitfield_write(&id_time, uint32_t,
 204                                 LTTNG_COMPACT_EVENT_BITS,
 205                                 LTTNG_COMPACT_TSC_BITS,
 206                                 ctx->tsc);
 207                 lib_ring_buffer_write(config, ctx, &id_time, sizeof(id_time));
 208                 break;
 209         }
 210         case 2: /* large */
 211         {
 212                 uint32_t timestamp = (uint32_t) ctx->tsc;
 213                 uint16_t id = event_id;
 214
 215                 lib_ring_buffer_write(config, ctx, &id, sizeof(id));
 216                 lib_ring_buffer_align_ctx(ctx, lttng_alignof(uint32_t));
 217                 lib_ring_buffer_write(config, ctx, &timestamp, sizeof(timestamp));
 218                 break;
 219         }
 220         default:
 221                 WARN_ON_ONCE(1);
 222         }
 223
 224         ctx_record(ctx, lttng_chan, lttng_ctx->chan_ctx);
 225         ctx_record(ctx, lttng_chan, lttng_ctx->event_ctx);
 226         lib_ring_buffer_align_ctx(ctx, ctx->largest_align);
 227
 228         return;
 229
 230 slow_path:
 231         lttng_write_event_header_slow(config, ctx, event_id);
 232 }
 233
 234 static
 235 void lttng_write_event_header_slow(const struct lttng_ust_lib_ring_buffer_config *config,
 236                                  struct lttng_ust_lib_ring_buffer_ctx *ctx,
 237                                  uint32_t event_id)
 238 {
 239         struct lttng_channel *lttng_chan = channel_get_private(ctx->chan);
 240         struct lttng_stack_ctx *lttng_ctx = ctx->priv2;
 241
 242         switch (lttng_chan->header_type) {
 243         case 1: /* compact */
 244                 if (!(ctx->rflags & (RING_BUFFER_RFLAG_FULL_TSC | LTTNG_RFLAG_EXTENDED))) {
 245                         uint32_t id_time = 0;
 246
 247                         bt_bitfield_write(&id_time, uint32_t,
 248                                         0,
 249                                         LTTNG_COMPACT_EVENT_BITS,
 250                                         event_id);
 251                         bt_bitfield_write(&id_time, uint32_t,
 252                                         LTTNG_COMPACT_EVENT_BITS,
 253                                         LTTNG_COMPACT_TSC_BITS,
 254                                         ctx->tsc);
 255                         lib_ring_buffer_write(config, ctx, &id_time, sizeof(id_time));
 256                 } else {
 257                         uint8_t id = 0;
 258                         uint64_t timestamp = ctx->tsc;
 259
 260                         bt_bitfield_write(&id, uint8_t,
 261                                         0,
 262                                         LTTNG_COMPACT_EVENT_BITS,
 263                                         31);
 264                         lib_ring_buffer_write(config, ctx, &id, sizeof(id));
 265                         /* Align extended struct on largest member */
 266                         lib_ring_buffer_align_ctx(ctx, lttng_alignof(uint64_t));
 267                         lib_ring_buffer_write(config, ctx, &event_id, sizeof(event_id));
 268                         lib_ring_buffer_align_ctx(ctx, lttng_alignof(uint64_t));
 269                         lib_ring_buffer_write(config, ctx, &timestamp, sizeof(timestamp));
 270                 }
 271                 break;
 272         case 2: /* large */
 273         {
 274                 if (!(ctx->rflags & (RING_BUFFER_RFLAG_FULL_TSC | LTTNG_RFLAG_EXTENDED))) {
 275                         uint32_t timestamp = (uint32_t) ctx->tsc;
 276                         uint16_t id = event_id;
 277
 278                         lib_ring_buffer_write(config, ctx, &id, sizeof(id));
 279                         lib_ring_buffer_align_ctx(ctx, lttng_alignof(uint32_t));
 280                         lib_ring_buffer_write(config, ctx, &timestamp, sizeof(timestamp));
 281                 } else {
 282                         uint16_t id = 65535;
 283                         uint64_t timestamp = ctx->tsc;
 284
 285                         lib_ring_buffer_write(config, ctx, &id, sizeof(id));
 286                         /* Align extended struct on largest member */
 287                         lib_ring_buffer_align_ctx(ctx, lttng_alignof(uint64_t));
 288                         lib_ring_buffer_write(config, ctx, &event_id, sizeof(event_id));
 289                         lib_ring_buffer_align_ctx(ctx, lttng_alignof(uint64_t));
 290                         lib_ring_buffer_write(config, ctx, &timestamp, sizeof(timestamp));
 291                 }
 292                 break;
 293         }
 294         default:
 295                 WARN_ON_ONCE(1);
 296         }
 297         ctx_record(ctx, lttng_chan, lttng_ctx->chan_ctx);
 298         ctx_record(ctx, lttng_chan, lttng_ctx->event_ctx);
 299         lib_ring_buffer_align_ctx(ctx, ctx->largest_align);
 300 }
 301
 302 static const struct lttng_ust_lib_ring_buffer_config client_config;
 303
 304 static uint64_t client_ring_buffer_clock_read(struct channel *chan)
 305 {
 306         return lib_ring_buffer_clock_read(chan);
 307 }
 308
 309 static
 310 size_t client_record_header_size(const struct lttng_ust_lib_ring_buffer_config *config,
 311                                  struct channel *chan, size_t offset,
 312                                  size_t *pre_header_padding,
 313                                  struct lttng_ust_lib_ring_buffer_ctx *ctx)
 314 {
 315         return record_header_size(config, chan, offset,
 316                                   pre_header_padding, ctx);
 317 }
 318
 319 /**
 320  * client_packet_header_size - called on buffer-switch to a new sub-buffer
 321  *
 322  * Return header size without padding after the structure. Don't use packed
 323  * structure because gcc generates inefficient code on some architectures
 324  * (powerpc, mips..)
 325  */
 326 static size_t client_packet_header_size(void)
 327 {
 328         return offsetof(struct packet_header, ctx.header_end);
 329 }
 330
 331 static void client_buffer_begin(struct lttng_ust_lib_ring_buffer *buf, uint64_t tsc,
 332                                 unsigned int subbuf_idx,
 333                                 struct lttng_ust_shm_handle *handle)
 334 {
 335         struct channel *chan = shmp(handle, buf->backend.chan);
 336         struct packet_header *header =
 337                 (struct packet_header *)
 338                         lib_ring_buffer_offset_address(&buf->backend,
 339                                 subbuf_idx * chan->backend.subbuf_size,
 340                                 handle);
 341         struct lttng_channel *lttng_chan = channel_get_private(chan);
 342
 343         assert(header);
 344         if (!header)
 345                 return;
 346         header->magic = CTF_MAGIC_NUMBER;
 347         memcpy(header->uuid, lttng_chan->uuid, sizeof(lttng_chan->uuid));
 348         header->stream_id = lttng_chan->id;
 349         header->stream_instance_id = buf->backend.cpu;
 350         header->ctx.timestamp_begin = tsc;
 351         header->ctx.timestamp_end = 0;
 352         header->ctx.content_size = ~0ULL; /* for debugging */
 353         header->ctx.packet_size = ~0ULL;
 354         header->ctx.events_discarded = 0;
 355         header->ctx.cpu_id = buf->backend.cpu;
 356 }
 357
 358 /*
 359  * offset is assumed to never be 0 here : never deliver a completely empty
 360  * subbuffer. data_size is between 1 and subbuf_size.
 361  */
 362 static void client_buffer_end(struct lttng_ust_lib_ring_buffer *buf, uint64_t tsc,
 363                               unsigned int subbuf_idx, unsigned long data_size,
 364                               struct lttng_ust_shm_handle *handle)
 365 {
 366         struct channel *chan = shmp(handle, buf->backend.chan);
 367         struct packet_header *header =
 368                 (struct packet_header *)
 369                         lib_ring_buffer_offset_address(&buf->backend,
 370                                 subbuf_idx * chan->backend.subbuf_size,
 371                                 handle);
 372         unsigned long records_lost = 0;
 373
 374         assert(header);
 375         if (!header)
 376                 return;
 377         header->ctx.timestamp_end = tsc;
 378         header->ctx.content_size =
 379                 (uint64_t) data_size * CHAR_BIT;                /* in bits */
 380         header->ctx.packet_size =
 381                 (uint64_t) PAGE_ALIGN(data_size) * CHAR_BIT;    /* in bits */
 382
 383         records_lost += lib_ring_buffer_get_records_lost_full(&client_config, buf);
 384         records_lost += lib_ring_buffer_get_records_lost_wrap(&client_config, buf);
 385         records_lost += lib_ring_buffer_get_records_lost_big(&client_config, buf);
 386         header->ctx.events_discarded = records_lost;
 387 }
 388
 389 static int client_buffer_create(struct lttng_ust_lib_ring_buffer *buf, void *priv,
 390                                 int cpu, const char *name, struct lttng_ust_shm_handle *handle)
 391 {
 392         return 0;
 393 }
 394
 395 static void client_buffer_finalize(struct lttng_ust_lib_ring_buffer *buf, void *priv, int cpu, struct lttng_ust_shm_handle *handle)
 396 {
 397 }
 398
 399 static void client_content_size_field(const struct lttng_ust_lib_ring_buffer_config *config,
 400                                       size_t *offset, size_t *length)
 401 {
 402         *offset = offsetof(struct packet_header, ctx.content_size);
 403         *length = sizeof(((struct packet_header *) NULL)->ctx.content_size);
 404 }
 405
 406 static void client_packet_size_field(const struct lttng_ust_lib_ring_buffer_config *config,
 407                                       size_t *offset, size_t *length)
 408 {
 409         *offset = offsetof(struct packet_header, ctx.packet_size);
 410         *length = sizeof(((struct packet_header *) NULL)->ctx.packet_size);
 411 }
 412
 413 static struct packet_header *client_packet_header(struct lttng_ust_lib_ring_buffer *buf,
 414                 struct lttng_ust_shm_handle *handle)
 415 {
 416         return lib_ring_buffer_read_offset_address(&buf->backend, 0, handle);
 417 }
 418
 419 static int client_timestamp_begin(struct lttng_ust_lib_ring_buffer *buf,
 420                 struct lttng_ust_shm_handle *handle,
 421                 uint64_t *timestamp_begin)
 422 {
 423         struct packet_header *header;
 424
 425         header = client_packet_header(buf, handle);
 426         if (!header)
 427                 return -1;
 428         *timestamp_begin = header->ctx.timestamp_begin;
 429         return 0;
 430 }
 431
 432 static int client_timestamp_end(struct lttng_ust_lib_ring_buffer *buf,
 433                 struct lttng_ust_shm_handle *handle,
 434                 uint64_t *timestamp_end)
 435 {
 436         struct packet_header *header;
 437
 438         header = client_packet_header(buf, handle);
 439         if (!header)
 440                 return -1;
 441         *timestamp_end = header->ctx.timestamp_end;
 442         return 0;
 443 }
 444
 445 static int client_events_discarded(struct lttng_ust_lib_ring_buffer *buf,
 446                 struct lttng_ust_shm_handle *handle,
 447                 uint64_t *events_discarded)
 448 {
 449         struct packet_header *header;
 450
 451         header = client_packet_header(buf, handle);
 452         if (!header)
 453                 return -1;
 454         *events_discarded = header->ctx.events_discarded;
 455         return 0;
 456 }
 457
 458 static int client_content_size(struct lttng_ust_lib_ring_buffer *buf,
 459                 struct lttng_ust_shm_handle *handle,
 460                 uint64_t *content_size)
 461 {
 462         struct packet_header *header;
 463
 464         header = client_packet_header(buf, handle);
 465         if (!header)
 466                 return -1;
 467         *content_size = header->ctx.content_size;
 468         return 0;
 469 }
 470
 471 static int client_packet_size(struct lttng_ust_lib_ring_buffer *buf,
 472                 struct lttng_ust_shm_handle *handle,
 473                 uint64_t *packet_size)
 474 {
 475         struct packet_header *header;
 476
 477         header = client_packet_header(buf, handle);
 478         if (!header)
 479                 return -1;
 480         *packet_size = header->ctx.packet_size;
 481         return 0;
 482 }
 483
 484 static int client_stream_id(struct lttng_ust_lib_ring_buffer *buf,
 485                 struct lttng_ust_shm_handle *handle,
 486                 uint64_t *stream_id)
 487 {
 488         struct packet_header *header;
 489
 490         header = client_packet_header(buf, handle);
 491         if (!header)
 492                 return -1;
 493         *stream_id = header->stream_id;
 494         return 0;
 495 }
 496
 497 static int client_current_timestamp(struct lttng_ust_lib_ring_buffer *buf,
 498                 struct lttng_ust_shm_handle *handle,
 499                 uint64_t *ts)
 500 {
 501         struct channel *chan;
 502
 503         chan = shmp(handle, handle->chan);
 504         *ts = client_ring_buffer_clock_read(chan);
 505
 506         return 0;
 507 }
 508
 509 static const
 510 struct lttng_ust_client_lib_ring_buffer_client_cb client_cb = {
 511         .parent = {
 512                 .ring_buffer_clock_read = client_ring_buffer_clock_read,
 513                 .record_header_size = client_record_header_size,
 514                 .subbuffer_header_size = client_packet_header_size,
 515                 .buffer_begin = client_buffer_begin,
 516                 .buffer_end = client_buffer_end,
 517                 .buffer_create = client_buffer_create,
 518                 .buffer_finalize = client_buffer_finalize,
 519                 .content_size_field = client_content_size_field,
 520                 .packet_size_field = client_packet_size_field,
 521         },
 522         .timestamp_begin = client_timestamp_begin,
 523         .timestamp_end = client_timestamp_end,
 524         .events_discarded = client_events_discarded,
 525         .content_size = client_content_size,
 526         .packet_size = client_packet_size,
 527         .stream_id = client_stream_id,
 528         .current_timestamp = client_current_timestamp,
 529 };
 530
 531 static const struct lttng_ust_lib_ring_buffer_config client_config = {
 532         .cb.ring_buffer_clock_read = client_ring_buffer_clock_read,
 533         .cb.record_header_size = client_record_header_size,
 534         .cb.subbuffer_header_size = client_packet_header_size,
 535         .cb.buffer_begin = client_buffer_begin,
 536         .cb.buffer_end = client_buffer_end,
 537         .cb.buffer_create = client_buffer_create,
 538         .cb.buffer_finalize = client_buffer_finalize,
 539         .cb.content_size_field = client_content_size_field,
 540         .cb.packet_size_field = client_packet_size_field,
 541
 542         .tsc_bits = LTTNG_COMPACT_TSC_BITS,
 543         .alloc = RING_BUFFER_ALLOC_PER_CPU,
 544         .sync = RING_BUFFER_SYNC_GLOBAL,
 545         .mode = RING_BUFFER_MODE_TEMPLATE,
 546         .backend = RING_BUFFER_PAGE,
 547         .output = RING_BUFFER_MMAP,
 548         .oops = RING_BUFFER_OOPS_CONSISTENCY,
 549         .ipi = RING_BUFFER_NO_IPI_BARRIER,
 550         .wakeup = LTTNG_CLIENT_WAKEUP,
 551         .client_type = LTTNG_CLIENT_TYPE,
 552
 553         .cb_ptr = &client_cb.parent,
 554 };
 555
 556 const struct lttng_ust_client_lib_ring_buffer_client_cb *LTTNG_CLIENT_CALLBACKS = &client_cb;
 557
 558 static
 559 struct lttng_channel *_channel_create(const char *name,
 560                                 void *buf_addr,
 561                                 size_t subbuf_size, size_t num_subbuf,
 562                                 unsigned int switch_timer_interval,
 563                                 unsigned int read_timer_interval,
 564                                 unsigned char *uuid,
 565                                 uint32_t chan_id,
 566                                 const int *stream_fds, int nr_stream_fds)
 567 {
 568         struct lttng_channel chan_priv_init;
 569         struct lttng_ust_shm_handle *handle;
 570         struct lttng_channel *lttng_chan;
 571         void *priv;
 572
 573         memset(&chan_priv_init, 0, sizeof(chan_priv_init));
 574         memcpy(chan_priv_init.uuid, uuid, LTTNG_UST_UUID_LEN);
 575         chan_priv_init.id = chan_id;
 576         handle = channel_create(&client_config, name,
 577                         &priv, __alignof__(struct lttng_channel),
 578                         sizeof(struct lttng_channel),
 579                         &chan_priv_init,
 580                         buf_addr, subbuf_size, num_subbuf,
 581                         switch_timer_interval, read_timer_interval,
 582                         stream_fds, nr_stream_fds);
 583         if (!handle)
 584                 return NULL;
 585         lttng_chan = priv;
 586         lttng_chan->handle = handle;
 587         lttng_chan->chan = shmp(handle, handle->chan);
 588         return lttng_chan;
 589 }
 590
 591 static
 592 void lttng_channel_destroy(struct lttng_channel *chan)
 593 {
 594         channel_destroy(chan->chan, chan->handle, 1);
 595 }
 596
 597 static
 598 int lttng_event_reserve(struct lttng_ust_lib_ring_buffer_ctx *ctx,
 599                       uint32_t event_id)
 600 {
 601         struct lttng_channel *lttng_chan = channel_get_private(ctx->chan);
 602         int ret, cpu;
 603
 604         cpu = lib_ring_buffer_get_cpu(&client_config);
 605         if (cpu < 0)
 606                 return -EPERM;
 607         ctx->cpu = cpu;
 608
 609         switch (lttng_chan->header_type) {
 610         case 1: /* compact */
 611                 if (event_id > 30)
 612                         ctx->rflags |= LTTNG_RFLAG_EXTENDED;
 613                 break;
 614         case 2: /* large */
 615                 if (event_id > 65534)
 616                         ctx->rflags |= LTTNG_RFLAG_EXTENDED;
 617                 break;
 618         default:
 619                 WARN_ON_ONCE(1);
 620         }
 621
 622         ret = lib_ring_buffer_reserve(&client_config, ctx);
 623         if (ret)
 624                 goto put;
 625         lttng_write_event_header(&client_config, ctx, event_id);
 626         return 0;
 627 put:
 628         lib_ring_buffer_put_cpu(&client_config);
 629         return ret;
 630 }
 631
 632 static
 633 void lttng_event_commit(struct lttng_ust_lib_ring_buffer_ctx *ctx)
 634 {
 635         lib_ring_buffer_commit(&client_config, ctx);
 636         lib_ring_buffer_put_cpu(&client_config);
 637 }
 638
 639 static
 640 void lttng_event_write(struct lttng_ust_lib_ring_buffer_ctx *ctx, const void *src,
 641                      size_t len)
 642 {
 643         lib_ring_buffer_write(&client_config, ctx, src, len);
 644 }
 645
 646 static
 647 void lttng_event_strcpy(struct lttng_ust_lib_ring_buffer_ctx *ctx, const char *src,
 648                      size_t len)
 649 {
 650         lib_ring_buffer_strcpy(&client_config, ctx, src, len, '#');
 651 }
 652
 653 #if 0
 654 static
 655 wait_queue_head_t *lttng_get_reader_wait_queue(struct channel *chan)
 656 {
 657         return &chan->read_wait;
 658 }
 659
 660 static
 661 wait_queue_head_t *lttng_get_hp_wait_queue(struct channel *chan)
 662 {
 663         return &chan->hp_wait;
 664 }
 665 #endif //0
 666
 667 static
 668 int lttng_is_finalized(struct channel *chan)
 669 {
 670         return lib_ring_buffer_channel_is_finalized(chan);
 671 }
 672
 673 static
 674 int lttng_is_disabled(struct channel *chan)
 675 {
 676         return lib_ring_buffer_channel_is_disabled(chan);
 677 }
 678
 679 static
 680 int lttng_flush_buffer(struct channel *chan, struct lttng_ust_shm_handle *handle)
 681 {
 682         struct lttng_ust_lib_ring_buffer *buf;
 683         int cpu;
 684
 685         for_each_channel_cpu(cpu, chan) {
 686                 int shm_fd, wait_fd, wakeup_fd;
 687                 uint64_t memory_map_size;
 688
 689                 buf = channel_get_ring_buffer(&client_config, chan,
 690                                 cpu, handle, &shm_fd, &wait_fd,
 691                                 &wakeup_fd, &memory_map_size);
 692                 lib_ring_buffer_switch(&client_config, buf,
 693                                 SWITCH_ACTIVE, handle);
 694         }
 695         return 0;
 696 }
 697
 698 static struct lttng_transport lttng_relay_transport = {
 699         .name = "relay-" RING_BUFFER_MODE_TEMPLATE_STRING "-mmap",
 700         .ops = {
 701                 .channel_create = _channel_create,
 702                 .channel_destroy = lttng_channel_destroy,
 703                 .u.has_strcpy = 1,
 704                 .event_reserve = lttng_event_reserve,
 705                 .event_commit = lttng_event_commit,
 706                 .event_write = lttng_event_write,
 707                 .packet_avail_size = NULL,      /* Would be racy anyway */
 708                 //.get_reader_wait_queue = lttng_get_reader_wait_queue,
 709                 //.get_hp_wait_queue = lttng_get_hp_wait_queue,
 710                 .is_finalized = lttng_is_finalized,
 711                 .is_disabled = lttng_is_disabled,
 712                 .flush_buffer = lttng_flush_buffer,
 713                 .event_strcpy = lttng_event_strcpy,
 714         },
 715         .client_config = &client_config,
 716 };
 717
 718 void RING_BUFFER_MODE_TEMPLATE_INIT(void)
 719 {
 720         DBG("LTT : ltt ring buffer client \"%s\" init\n",
 721                 "relay-" RING_BUFFER_MODE_TEMPLATE_STRING "-mmap");
 722         lttng_transport_register(&lttng_relay_transport);
 723 }
 724
 725 void RING_BUFFER_MODE_TEMPLATE_EXIT(void)
 726 {
 727         DBG("LTT : ltt ring buffer client \"%s\" exit\n",
 728                 "relay-" RING_BUFFER_MODE_TEMPLATE_STRING "-mmap");
 729         lttng_transport_unregister(&lttng_relay_transport);
 730 }