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

   1 /*
   2  * ltt-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-ust-uuid.h"
  28 #include "ltt-tracer.h"
  29 #include "../libringbuffer/frontend_types.h"
  30
  31 #define LTTNG_COMPACT_EVENT_BITS       5
  32 #define LTTNG_COMPACT_TSC_BITS         27
  33
  34 /*
  35  * Keep the natural field alignment for _each field_ within this structure if
  36  * you ever add/remove a field from this header. Packed attribute is not used
  37  * because gcc generates poor code on at least powerpc and mips. Don't ever
  38  * let gcc add padding between the structure elements.
  39  */
  40
  41 struct packet_header {
  42         /* Trace packet header */
  43         uint32_t magic;                 /*
  44                                          * Trace magic number.
  45                                          * contains endianness information.
  46                                          */
  47         uint8_t uuid[LTTNG_UST_UUID_LEN];
  48         uint32_t stream_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                 uint32_t events_discarded;      /*
  55                                                  * Events lost in this subbuffer since
  56                                                  * the beginning of the trace.
  57                                                  * (may overflow)
  58                                                  */
  59                 uint32_t content_size;          /* Size of data in subbuffer */
  60                 uint32_t packet_size;           /* Subbuffer size (include padding) */
  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         for (i = 0; i < ctx->nr_fields; i++)
  81                 offset += ctx->fields[i].get_size(offset);
  82         return offset - orig_offset;
  83 }
  84
  85 static inline
  86 void ctx_record(struct lttng_ust_lib_ring_buffer_ctx *bufctx,
  87                 struct ltt_channel *chan,
  88                 struct lttng_ctx *ctx)
  89 {
  90         int i;
  91
  92         if (caa_likely(!ctx))
  93                 return;
  94         for (i = 0; i < ctx->nr_fields; i++)
  95                 ctx->fields[i].record(&ctx->fields[i], bufctx, chan);
  96 }
  97
  98 /*
  99  * record_header_size - Calculate the header size and padding necessary.
 100  * @config: ring buffer instance configuration
 101  * @chan: channel
 102  * @offset: offset in the write buffer
 103  * @pre_header_padding: padding to add before the header (output)
 104  * @ctx: reservation context
 105  *
 106  * Returns the event header size (including padding).
 107  *
 108  * The payload must itself determine its own alignment from the biggest type it
 109  * contains.
 110  */
 111 static __inline__
 112 unsigned char record_header_size(const struct lttng_ust_lib_ring_buffer_config *config,
 113                                  struct channel *chan, size_t offset,
 114                                  size_t *pre_header_padding,
 115                                  struct lttng_ust_lib_ring_buffer_ctx *ctx)
 116 {
 117         struct ltt_channel *ltt_chan = channel_get_private(chan);
 118         struct ltt_event *event = ctx->priv;
 119         size_t orig_offset = offset;
 120         size_t padding;
 121
 122         switch (ltt_chan->header_type) {
 123         case 1: /* compact */
 124                 padding = lib_ring_buffer_align(offset, lttng_alignof(uint32_t));
 125                 offset += padding;
 126                 if (!(ctx->rflags & (RING_BUFFER_RFLAG_FULL_TSC | LTT_RFLAG_EXTENDED))) {
 127                         offset += sizeof(uint32_t);     /* id and timestamp */
 128                 } else {
 129                         /* Minimum space taken by LTTNG_COMPACT_EVENT_BITS id */
 130                         offset += (LTTNG_COMPACT_EVENT_BITS + CHAR_BIT - 1) / CHAR_BIT;
 131                         /* Align extended struct on largest member */
 132                         offset += lib_ring_buffer_align(offset, lttng_alignof(uint64_t));
 133                         offset += sizeof(uint32_t);     /* id */
 134                         offset += lib_ring_buffer_align(offset, lttng_alignof(uint64_t));
 135                         offset += sizeof(uint64_t);     /* timestamp */
 136                 }
 137                 break;
 138         case 2: /* large */
 139                 padding = lib_ring_buffer_align(offset, lttng_alignof(uint16_t));
 140                 offset += padding;
 141                 offset += sizeof(uint16_t);
 142                 if (!(ctx->rflags & (RING_BUFFER_RFLAG_FULL_TSC | LTT_RFLAG_EXTENDED))) {
 143                         offset += lib_ring_buffer_align(offset, lttng_alignof(uint32_t));
 144                         offset += sizeof(uint32_t);     /* timestamp */
 145                 } else {
 146                         /* Align extended struct on largest member */
 147                         offset += lib_ring_buffer_align(offset, lttng_alignof(uint64_t));
 148                         offset += sizeof(uint32_t);     /* id */
 149                         offset += lib_ring_buffer_align(offset, lttng_alignof(uint64_t));
 150                         offset += sizeof(uint64_t);     /* timestamp */
 151                 }
 152                 break;
 153         default:
 154                 padding = 0;
 155                 WARN_ON_ONCE(1);
 156         }
 157         offset += ctx_get_size(offset, event->ctx);
 158         offset += ctx_get_size(offset, ltt_chan->ctx);
 159
 160         *pre_header_padding = padding;
 161         return offset - orig_offset;
 162 }
 163
 164 #include "../libringbuffer/api.h"
 165
 166 static
 167 void ltt_write_event_header_slow(const struct lttng_ust_lib_ring_buffer_config *config,
 168                                  struct lttng_ust_lib_ring_buffer_ctx *ctx,
 169                                  uint32_t event_id);
 170
 171 /*
 172  * ltt_write_event_header
 173  *
 174  * Writes the event header to the offset (already aligned on 32-bits).
 175  *
 176  * @config: ring buffer instance configuration
 177  * @ctx: reservation context
 178  * @event_id: event ID
 179  */
 180 static __inline__
 181 void ltt_write_event_header(const struct lttng_ust_lib_ring_buffer_config *config,
 182                             struct lttng_ust_lib_ring_buffer_ctx *ctx,
 183                             uint32_t event_id)
 184 {
 185         struct ltt_channel *ltt_chan = channel_get_private(ctx->chan);
 186         struct ltt_event *event = ctx->priv;
 187
 188         if (caa_unlikely(ctx->rflags))
 189                 goto slow_path;
 190
 191         switch (ltt_chan->header_type) {
 192         case 1: /* compact */
 193         {
 194                 uint32_t id_time = 0;
 195
 196                 bt_bitfield_write(&id_time, uint32_t,
 197                                 0,
 198                                 LTTNG_COMPACT_EVENT_BITS,
 199                                 event_id);
 200                 bt_bitfield_write(&id_time, uint32_t,
 201                                 LTTNG_COMPACT_EVENT_BITS,
 202                                 LTTNG_COMPACT_TSC_BITS,
 203                                 ctx->tsc);
 204                 lib_ring_buffer_write(config, ctx, &id_time, sizeof(id_time));
 205                 break;
 206         }
 207         case 2: /* large */
 208         {
 209                 uint32_t timestamp = (uint32_t) ctx->tsc;
 210                 uint16_t id = event_id;
 211
 212                 lib_ring_buffer_write(config, ctx, &id, sizeof(id));
 213                 lib_ring_buffer_align_ctx(ctx, lttng_alignof(uint32_t));
 214                 lib_ring_buffer_write(config, ctx, &timestamp, sizeof(timestamp));
 215                 break;
 216         }
 217         default:
 218                 WARN_ON_ONCE(1);
 219         }
 220
 221         ctx_record(ctx, ltt_chan, ltt_chan->ctx);
 222         ctx_record(ctx, ltt_chan, event->ctx);
 223         lib_ring_buffer_align_ctx(ctx, ctx->largest_align);
 224
 225         return;
 226
 227 slow_path:
 228         ltt_write_event_header_slow(config, ctx, event_id);
 229 }
 230
 231 static
 232 void ltt_write_event_header_slow(const struct lttng_ust_lib_ring_buffer_config *config,
 233                                  struct lttng_ust_lib_ring_buffer_ctx *ctx,
 234                                  uint32_t event_id)
 235 {
 236         struct ltt_channel *ltt_chan = channel_get_private(ctx->chan);
 237         struct ltt_event *event = ctx->priv;
 238
 239         switch (ltt_chan->header_type) {
 240         case 1: /* compact */
 241                 if (!(ctx->rflags & (RING_BUFFER_RFLAG_FULL_TSC | LTT_RFLAG_EXTENDED))) {
 242                         uint32_t id_time = 0;
 243
 244                         bt_bitfield_write(&id_time, uint32_t,
 245                                         0,
 246                                         LTTNG_COMPACT_EVENT_BITS,
 247                                         event_id);
 248                         bt_bitfield_write(&id_time, uint32_t,
 249                                         LTTNG_COMPACT_EVENT_BITS,
 250                                         LTTNG_COMPACT_TSC_BITS,
 251                                         ctx->tsc);
 252                         lib_ring_buffer_write(config, ctx, &id_time, sizeof(id_time));
 253                 } else {
 254                         uint8_t id = 0;
 255                         uint64_t timestamp = ctx->tsc;
 256
 257                         bt_bitfield_write(&id, uint8_t,
 258                                         0,
 259                                         LTTNG_COMPACT_EVENT_BITS,
 260                                         31);
 261                         lib_ring_buffer_write(config, ctx, &id, sizeof(id));
 262                         /* Align extended struct on largest member */
 263                         lib_ring_buffer_align_ctx(ctx, lttng_alignof(uint64_t));
 264                         lib_ring_buffer_write(config, ctx, &event_id, sizeof(event_id));
 265                         lib_ring_buffer_align_ctx(ctx, lttng_alignof(uint64_t));
 266                         lib_ring_buffer_write(config, ctx, &timestamp, sizeof(timestamp));
 267                 }
 268                 break;
 269         case 2: /* large */
 270         {
 271                 if (!(ctx->rflags & (RING_BUFFER_RFLAG_FULL_TSC | LTT_RFLAG_EXTENDED))) {
 272                         uint32_t timestamp = (uint32_t) ctx->tsc;
 273                         uint16_t id = event_id;
 274
 275                         lib_ring_buffer_write(config, ctx, &id, sizeof(id));
 276                         lib_ring_buffer_align_ctx(ctx, lttng_alignof(uint32_t));
 277                         lib_ring_buffer_write(config, ctx, &timestamp, sizeof(timestamp));
 278                 } else {
 279                         uint16_t id = 65535;
 280                         uint64_t timestamp = ctx->tsc;
 281
 282                         lib_ring_buffer_write(config, ctx, &id, sizeof(id));
 283                         /* Align extended struct on largest member */
 284                         lib_ring_buffer_align_ctx(ctx, lttng_alignof(uint64_t));
 285                         lib_ring_buffer_write(config, ctx, &event_id, sizeof(event_id));
 286                         lib_ring_buffer_align_ctx(ctx, lttng_alignof(uint64_t));
 287                         lib_ring_buffer_write(config, ctx, &timestamp, sizeof(timestamp));
 288                 }
 289                 break;
 290         }
 291         default:
 292                 WARN_ON_ONCE(1);
 293         }
 294         ctx_record(ctx, ltt_chan, ltt_chan->ctx);
 295         ctx_record(ctx, ltt_chan, event->ctx);
 296         lib_ring_buffer_align_ctx(ctx, ctx->largest_align);
 297 }
 298
 299 static const struct lttng_ust_lib_ring_buffer_config client_config;
 300
 301 static uint64_t client_ring_buffer_clock_read(struct channel *chan)
 302 {
 303         return lib_ring_buffer_clock_read(chan);
 304 }
 305
 306 static
 307 size_t client_record_header_size(const struct lttng_ust_lib_ring_buffer_config *config,
 308                                  struct channel *chan, size_t offset,
 309                                  size_t *pre_header_padding,
 310                                  struct lttng_ust_lib_ring_buffer_ctx *ctx)
 311 {
 312         return record_header_size(config, chan, offset,
 313                                   pre_header_padding, ctx);
 314 }
 315
 316 /**
 317  * client_packet_header_size - called on buffer-switch to a new sub-buffer
 318  *
 319  * Return header size without padding after the structure. Don't use packed
 320  * structure because gcc generates inefficient code on some architectures
 321  * (powerpc, mips..)
 322  */
 323 static size_t client_packet_header_size(void)
 324 {
 325         return offsetof(struct packet_header, ctx.header_end);
 326 }
 327
 328 static void client_buffer_begin(struct lttng_ust_lib_ring_buffer *buf, uint64_t tsc,
 329                                 unsigned int subbuf_idx,
 330                                 struct lttng_ust_shm_handle *handle)
 331 {
 332         struct channel *chan = shmp(handle, buf->backend.chan);
 333         struct packet_header *header =
 334                 (struct packet_header *)
 335                         lib_ring_buffer_offset_address(&buf->backend,
 336                                 subbuf_idx * chan->backend.subbuf_size,
 337                                 handle);
 338         struct ltt_channel *ltt_chan = channel_get_private(chan);
 339
 340         header->magic = CTF_MAGIC_NUMBER;
 341         memcpy(header->uuid, ltt_chan->uuid, sizeof(ltt_chan->uuid));
 342         header->stream_id = ltt_chan->id;
 343         header->ctx.timestamp_begin = tsc;
 344         header->ctx.timestamp_end = 0;
 345         header->ctx.events_discarded = 0;
 346         header->ctx.content_size = 0xFFFFFFFF; /* for debugging */
 347         header->ctx.packet_size = 0xFFFFFFFF;
 348         header->ctx.cpu_id = buf->backend.cpu;
 349 }
 350
 351 /*
 352  * offset is assumed to never be 0 here : never deliver a completely empty
 353  * subbuffer. data_size is between 1 and subbuf_size.
 354  */
 355 static void client_buffer_end(struct lttng_ust_lib_ring_buffer *buf, uint64_t tsc,
 356                               unsigned int subbuf_idx, unsigned long data_size,
 357                               struct lttng_ust_shm_handle *handle)
 358 {
 359         struct channel *chan = shmp(handle, buf->backend.chan);
 360         struct packet_header *header =
 361                 (struct packet_header *)
 362                         lib_ring_buffer_offset_address(&buf->backend,
 363                                 subbuf_idx * chan->backend.subbuf_size,
 364                                 handle);
 365         unsigned long records_lost = 0;
 366
 367         header->ctx.timestamp_end = tsc;
 368         header->ctx.content_size = data_size * CHAR_BIT;        /* in bits */
 369         header->ctx.packet_size = PAGE_ALIGN(data_size) * CHAR_BIT; /* in bits */
 370
 371         records_lost += lib_ring_buffer_get_records_lost_full(&client_config, buf);
 372         records_lost += lib_ring_buffer_get_records_lost_wrap(&client_config, buf);
 373         records_lost += lib_ring_buffer_get_records_lost_big(&client_config, buf);
 374         header->ctx.events_discarded = records_lost;
 375 }
 376
 377 static int client_buffer_create(struct lttng_ust_lib_ring_buffer *buf, void *priv,
 378                                 int cpu, const char *name, struct lttng_ust_shm_handle *handle)
 379 {
 380         return 0;
 381 }
 382
 383 static void client_buffer_finalize(struct lttng_ust_lib_ring_buffer *buf, void *priv, int cpu, struct lttng_ust_shm_handle *handle)
 384 {
 385 }
 386
 387 static const struct lttng_ust_lib_ring_buffer_config client_config = {
 388         .cb.ring_buffer_clock_read = client_ring_buffer_clock_read,
 389         .cb.record_header_size = client_record_header_size,
 390         .cb.subbuffer_header_size = client_packet_header_size,
 391         .cb.buffer_begin = client_buffer_begin,
 392         .cb.buffer_end = client_buffer_end,
 393         .cb.buffer_create = client_buffer_create,
 394         .cb.buffer_finalize = client_buffer_finalize,
 395
 396         .tsc_bits = LTTNG_COMPACT_TSC_BITS,
 397         .alloc = RING_BUFFER_ALLOC_PER_CPU,
 398         .sync = RING_BUFFER_SYNC_GLOBAL,
 399         .mode = RING_BUFFER_MODE_TEMPLATE,
 400         .backend = RING_BUFFER_PAGE,
 401         .output = RING_BUFFER_MMAP,
 402         .oops = RING_BUFFER_OOPS_CONSISTENCY,
 403         .ipi = RING_BUFFER_NO_IPI_BARRIER,
 404         .wakeup = RING_BUFFER_WAKEUP_BY_WRITER,
 405         .client_type = LTTNG_CLIENT_TYPE,
 406 };
 407
 408 const struct lttng_ust_lib_ring_buffer_client_cb *LTTNG_CLIENT_CALLBACKS = &client_config.cb;
 409
 410 static
 411 struct ltt_channel *_channel_create(const char *name,
 412                                 void *buf_addr,
 413                                 size_t subbuf_size, size_t num_subbuf,
 414                                 unsigned int switch_timer_interval,
 415                                 unsigned int read_timer_interval,
 416                                 int **shm_fd, char **shm_path,
 417                                 int **wait_fd, char **wait_pipe_path,
 418                                 uint64_t **memory_map_size,
 419                                 struct ltt_channel *chan_priv_init)
 420 {
 421         void *priv;
 422         struct ltt_channel *ltt_chan = NULL;
 423         struct lttng_ust_shm_handle *handle;
 424
 425         handle = channel_create(&client_config, name,
 426                         &priv, __alignof__(*ltt_chan), sizeof(*ltt_chan),
 427                         chan_priv_init,
 428                         buf_addr, subbuf_size, num_subbuf,
 429                         switch_timer_interval, read_timer_interval,
 430                         shm_fd, shm_path, wait_fd, wait_pipe_path,
 431                         memory_map_size);
 432         if (!handle)
 433                 return NULL;
 434         ltt_chan = priv;
 435         ltt_chan->handle = handle;
 436         ltt_chan->chan = shmp(ltt_chan->handle, ltt_chan->handle->chan);
 437         return ltt_chan;
 438 }
 439
 440 static
 441 void ltt_channel_destroy(struct ltt_channel *ltt_chan)
 442 {
 443         channel_destroy(ltt_chan->chan, ltt_chan->handle, 0);
 444 }
 445
 446 static
 447 struct lttng_ust_lib_ring_buffer *ltt_buffer_read_open(struct channel *chan,
 448                                                        struct lttng_ust_shm_handle *handle,
 449                                                        int **shm_fd, char **shm_path,
 450                                                        int **wait_fd, char **wait_pipe_path,
 451                                                        uint64_t **memory_map_size)
 452 {
 453         struct lttng_ust_lib_ring_buffer *buf;
 454         int cpu;
 455
 456         for_each_channel_cpu(cpu, chan) {
 457                 buf = channel_get_ring_buffer(&client_config, chan,
 458                                               cpu, handle, shm_fd, shm_path,
 459                                               wait_fd, wait_pipe_path,
 460                                               memory_map_size);
 461                 if (!lib_ring_buffer_open_read(buf, handle, 0))
 462                         return buf;
 463         }
 464         return NULL;
 465 }
 466
 467 static
 468 void ltt_buffer_read_close(struct lttng_ust_lib_ring_buffer *buf,
 469                            struct lttng_ust_shm_handle *handle)
 470 {
 471         lib_ring_buffer_release_read(buf, handle, 0);
 472 }
 473
 474 static
 475 int ltt_event_reserve(struct lttng_ust_lib_ring_buffer_ctx *ctx,
 476                       uint32_t event_id)
 477 {
 478         struct ltt_channel *ltt_chan = channel_get_private(ctx->chan);
 479         int ret, cpu;
 480
 481         cpu = lib_ring_buffer_get_cpu(&client_config);
 482         if (cpu < 0)
 483                 return -EPERM;
 484         ctx->cpu = cpu;
 485
 486         switch (ltt_chan->header_type) {
 487         case 1: /* compact */
 488                 if (event_id > 30)
 489                         ctx->rflags |= LTT_RFLAG_EXTENDED;
 490                 break;
 491         case 2: /* large */
 492                 if (event_id > 65534)
 493                         ctx->rflags |= LTT_RFLAG_EXTENDED;
 494                 break;
 495         default:
 496                 WARN_ON_ONCE(1);
 497         }
 498
 499         ret = lib_ring_buffer_reserve(&client_config, ctx);
 500         if (ret)
 501                 goto put;
 502         ltt_write_event_header(&client_config, ctx, event_id);
 503         return 0;
 504 put:
 505         lib_ring_buffer_put_cpu(&client_config);
 506         return ret;
 507 }
 508
 509 static
 510 void ltt_event_commit(struct lttng_ust_lib_ring_buffer_ctx *ctx)
 511 {
 512         lib_ring_buffer_commit(&client_config, ctx);
 513         lib_ring_buffer_put_cpu(&client_config);
 514 }
 515
 516 static
 517 void ltt_event_write(struct lttng_ust_lib_ring_buffer_ctx *ctx, const void *src,
 518                      size_t len)
 519 {
 520         lib_ring_buffer_write(&client_config, ctx, src, len);
 521 }
 522
 523 #if 0
 524 static
 525 wait_queue_head_t *ltt_get_reader_wait_queue(struct channel *chan)
 526 {
 527         return &chan->read_wait;
 528 }
 529
 530 static
 531 wait_queue_head_t *ltt_get_hp_wait_queue(struct channel *chan)
 532 {
 533         return &chan->hp_wait;
 534 }
 535 #endif //0
 536
 537 static
 538 int ltt_is_finalized(struct channel *chan)
 539 {
 540         return lib_ring_buffer_channel_is_finalized(chan);
 541 }
 542
 543 static
 544 int ltt_is_disabled(struct channel *chan)
 545 {
 546         return lib_ring_buffer_channel_is_disabled(chan);
 547 }
 548
 549 static
 550 int ltt_flush_buffer(struct channel *chan, struct lttng_ust_shm_handle *handle)
 551 {
 552         struct lttng_ust_lib_ring_buffer *buf;
 553         int cpu;
 554
 555         for_each_channel_cpu(cpu, chan) {
 556                 int *shm_fd, *wait_fd;
 557                 char *shm_path, *wait_pipe_path;
 558                 uint64_t *memory_map_size;
 559
 560                 buf = channel_get_ring_buffer(&client_config, chan,
 561                                               cpu, handle, &shm_fd, &shm_path,
 562                                               &wait_fd, &wait_pipe_path,
 563                                               &memory_map_size);
 564                 lib_ring_buffer_switch(&client_config, buf,
 565                                 SWITCH_ACTIVE, handle);
 566         }
 567         return 0;
 568 }
 569
 570 static struct ltt_transport ltt_relay_transport = {
 571         .name = "relay-" RING_BUFFER_MODE_TEMPLATE_STRING "-mmap",
 572         .ops = {
 573                 .channel_create = _channel_create,
 574                 .channel_destroy = ltt_channel_destroy,
 575                 .buffer_read_open = ltt_buffer_read_open,
 576                 .buffer_read_close = ltt_buffer_read_close,
 577                 .event_reserve = ltt_event_reserve,
 578                 .event_commit = ltt_event_commit,
 579                 .event_write = ltt_event_write,
 580                 .packet_avail_size = NULL,      /* Would be racy anyway */
 581                 //.get_reader_wait_queue = ltt_get_reader_wait_queue,
 582                 //.get_hp_wait_queue = ltt_get_hp_wait_queue,
 583                 .is_finalized = ltt_is_finalized,
 584                 .is_disabled = ltt_is_disabled,
 585                 .flush_buffer = ltt_flush_buffer,
 586         },
 587 };
 588
 589 void RING_BUFFER_MODE_TEMPLATE_INIT(void)
 590 {
 591         DBG("LTT : ltt ring buffer client init\n");
 592         ltt_transport_register(&ltt_relay_transport);
 593 }
 594
 595 void RING_BUFFER_MODE_TEMPLATE_EXIT(void)
 596 {
 597         DBG("LTT : ltt ring buffer client exit\n");
 598         ltt_transport_unregister(&ltt_relay_transport);
 599 }