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 "ltt-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[16];
  47         uint32_t stream_id;
  48
  49         struct {
  50                 /* Stream packet context */
  51                 uint64_t timestamp_begin;       /* Cycle count at subbuffer start */
  52                 uint64_t timestamp_end;         /* Cycle count at subbuffer end */
  53                 uint32_t events_discarded;      /*
  54                                                  * Events lost in this subbuffer since
  55                                                  * the beginning of the trace.
  56                                                  * (may overflow)
  57                                                  */
  58                 uint32_t content_size;          /* Size of data in subbuffer */
  59                 uint32_t packet_size;           /* Subbuffer size (include padding) */
  60                 uint32_t cpu_id;                /* CPU id associated with stream */
  61                 uint8_t header_end;             /* End of header */
  62         } ctx;
  63 };
  64
  65
  66 static inline uint64_t lib_ring_buffer_clock_read(struct channel *chan)
  67 {
  68         return trace_clock_read64();
  69 }
  70
  71 static inline
  72 size_t ctx_get_size(size_t offset, struct lttng_ctx *ctx)
  73 {
  74         int i;
  75         size_t orig_offset = offset;
  76
  77         if (caa_likely(!ctx))
  78                 return 0;
  79         for (i = 0; i < ctx->nr_fields; i++)
  80                 offset += ctx->fields[i].get_size(offset);
  81         return offset - orig_offset;
  82 }
  83
  84 static inline
  85 void ctx_record(struct lttng_ust_lib_ring_buffer_ctx *bufctx,
  86                 struct ltt_channel *chan,
  87                 struct lttng_ctx *ctx)
  88 {
  89         int i;
  90
  91         if (caa_likely(!ctx))
  92                 return;
  93         for (i = 0; i < ctx->nr_fields; i++)
  94                 ctx->fields[i].record(&ctx->fields[i], bufctx, chan);
  95 }
  96
  97 /*
  98  * record_header_size - Calculate the header size and padding necessary.
  99  * @config: ring buffer instance configuration
 100  * @chan: channel
 101  * @offset: offset in the write buffer
 102  * @pre_header_padding: padding to add before the header (output)
 103  * @ctx: reservation context
 104  *
 105  * Returns the event header size (including padding).
 106  *
 107  * The payload must itself determine its own alignment from the biggest type it
 108  * contains.
 109  */
 110 static __inline__
 111 unsigned char record_header_size(const struct lttng_ust_lib_ring_buffer_config *config,
 112                                  struct channel *chan, size_t offset,
 113                                  size_t *pre_header_padding,
 114                                  struct lttng_ust_lib_ring_buffer_ctx *ctx)
 115 {
 116         struct ltt_channel *ltt_chan = channel_get_private(chan);
 117         struct ltt_event *event = ctx->priv;
 118         size_t orig_offset = offset;
 119         size_t padding;
 120
 121         switch (ltt_chan->header_type) {
 122         case 1: /* compact */
 123                 padding = lib_ring_buffer_align(offset, lttng_alignof(uint32_t));
 124                 offset += padding;
 125                 if (!(ctx->rflags & (RING_BUFFER_RFLAG_FULL_TSC | LTT_RFLAG_EXTENDED))) {
 126                         offset += sizeof(uint32_t);     /* id and timestamp */
 127                 } else {
 128                         /* Minimum space taken by LTTNG_COMPACT_EVENT_BITS id */
 129                         offset += (LTTNG_COMPACT_EVENT_BITS + CHAR_BIT - 1) / CHAR_BIT;
 130                         /* Align extended struct on largest member */
 131                         offset += lib_ring_buffer_align(offset, lttng_alignof(uint64_t));
 132                         offset += sizeof(uint32_t);     /* id */
 133                         offset += lib_ring_buffer_align(offset, lttng_alignof(uint64_t));
 134                         offset += sizeof(uint64_t);     /* timestamp */
 135                 }
 136                 break;
 137         case 2: /* large */
 138                 padding = lib_ring_buffer_align(offset, lttng_alignof(uint16_t));
 139                 offset += padding;
 140                 offset += sizeof(uint16_t);
 141                 if (!(ctx->rflags & (RING_BUFFER_RFLAG_FULL_TSC | LTT_RFLAG_EXTENDED))) {
 142                         offset += lib_ring_buffer_align(offset, lttng_alignof(uint32_t));
 143                         offset += sizeof(uint32_t);     /* timestamp */
 144                 } else {
 145                         /* Align extended struct on largest member */
 146                         offset += lib_ring_buffer_align(offset, lttng_alignof(uint64_t));
 147                         offset += sizeof(uint32_t);     /* id */
 148                         offset += lib_ring_buffer_align(offset, lttng_alignof(uint64_t));
 149                         offset += sizeof(uint64_t);     /* timestamp */
 150                 }
 151                 break;
 152         default:
 153                 padding = 0;
 154                 WARN_ON_ONCE(1);
 155         }
 156         offset += ctx_get_size(offset, event->ctx);
 157         offset += ctx_get_size(offset, ltt_chan->ctx);
 158
 159         *pre_header_padding = padding;
 160         return offset - orig_offset;
 161 }
 162
 163 #include "../libringbuffer/api.h"
 164
 165 static
 166 void ltt_write_event_header_slow(const struct lttng_ust_lib_ring_buffer_config *config,
 167                                  struct lttng_ust_lib_ring_buffer_ctx *ctx,
 168                                  uint32_t event_id);
 169
 170 /*
 171  * ltt_write_event_header
 172  *
 173  * Writes the event header to the offset (already aligned on 32-bits).
 174  *
 175  * @config: ring buffer instance configuration
 176  * @ctx: reservation context
 177  * @event_id: event ID
 178  */
 179 static __inline__
 180 void ltt_write_event_header(const struct lttng_ust_lib_ring_buffer_config *config,
 181                             struct lttng_ust_lib_ring_buffer_ctx *ctx,
 182                             uint32_t event_id)
 183 {
 184         struct ltt_channel *ltt_chan = channel_get_private(ctx->chan);
 185         struct ltt_event *event = ctx->priv;
 186
 187         if (caa_unlikely(ctx->rflags))
 188                 goto slow_path;
 189
 190         switch (ltt_chan->header_type) {
 191         case 1: /* compact */
 192         {
 193                 uint32_t id_time = 0;
 194
 195                 bt_bitfield_write(&id_time, uint32_t,
 196                                 0,
 197                                 LTTNG_COMPACT_EVENT_BITS,
 198                                 event_id);
 199                 bt_bitfield_write(&id_time, uint32_t,
 200                                 LTTNG_COMPACT_EVENT_BITS,
 201                                 LTTNG_COMPACT_TSC_BITS,
 202                                 ctx->tsc);
 203                 lib_ring_buffer_write(config, ctx, &id_time, sizeof(id_time));
 204                 break;
 205         }
 206         case 2: /* large */
 207         {
 208                 uint32_t timestamp = (uint32_t) ctx->tsc;
 209                 uint16_t id = event_id;
 210
 211                 lib_ring_buffer_write(config, ctx, &id, sizeof(id));
 212                 lib_ring_buffer_align_ctx(ctx, lttng_alignof(uint32_t));
 213                 lib_ring_buffer_write(config, ctx, &timestamp, sizeof(timestamp));
 214                 break;
 215         }
 216         default:
 217                 WARN_ON_ONCE(1);
 218         }
 219
 220         ctx_record(ctx, ltt_chan, ltt_chan->ctx);
 221         ctx_record(ctx, ltt_chan, event->ctx);
 222         lib_ring_buffer_align_ctx(ctx, ctx->largest_align);
 223
 224         return;
 225
 226 slow_path:
 227         ltt_write_event_header_slow(config, ctx, event_id);
 228 }
 229
 230 static
 231 void ltt_write_event_header_slow(const struct lttng_ust_lib_ring_buffer_config *config,
 232                                  struct lttng_ust_lib_ring_buffer_ctx *ctx,
 233                                  uint32_t event_id)
 234 {
 235         struct ltt_channel *ltt_chan = channel_get_private(ctx->chan);
 236         struct ltt_event *event = ctx->priv;
 237
 238         switch (ltt_chan->header_type) {
 239         case 1: /* compact */
 240                 if (!(ctx->rflags & (RING_BUFFER_RFLAG_FULL_TSC | LTT_RFLAG_EXTENDED))) {
 241                         uint32_t id_time = 0;
 242
 243                         bt_bitfield_write(&id_time, uint32_t,
 244                                         0,
 245                                         LTTNG_COMPACT_EVENT_BITS,
 246                                         event_id);
 247                         bt_bitfield_write(&id_time, uint32_t,
 248                                         LTTNG_COMPACT_EVENT_BITS,
 249                                         LTTNG_COMPACT_TSC_BITS,
 250                                         ctx->tsc);
 251                         lib_ring_buffer_write(config, ctx, &id_time, sizeof(id_time));
 252                 } else {
 253                         uint8_t id = 0;
 254                         uint64_t timestamp = ctx->tsc;
 255
 256                         bt_bitfield_write(&id, uint8_t,
 257                                         0,
 258                                         LTTNG_COMPACT_EVENT_BITS,
 259                                         31);
 260                         lib_ring_buffer_write(config, ctx, &id, sizeof(id));
 261                         /* Align extended struct on largest member */
 262                         lib_ring_buffer_align_ctx(ctx, lttng_alignof(uint64_t));
 263                         lib_ring_buffer_write(config, ctx, &event_id, sizeof(event_id));
 264                         lib_ring_buffer_align_ctx(ctx, lttng_alignof(uint64_t));
 265                         lib_ring_buffer_write(config, ctx, &timestamp, sizeof(timestamp));
 266                 }
 267                 break;
 268         case 2: /* large */
 269         {
 270                 if (!(ctx->rflags & (RING_BUFFER_RFLAG_FULL_TSC | LTT_RFLAG_EXTENDED))) {
 271                         uint32_t timestamp = (uint32_t) ctx->tsc;
 272                         uint16_t id = event_id;
 273
 274                         lib_ring_buffer_write(config, ctx, &id, sizeof(id));
 275                         lib_ring_buffer_align_ctx(ctx, lttng_alignof(uint32_t));
 276                         lib_ring_buffer_write(config, ctx, &timestamp, sizeof(timestamp));
 277                 } else {
 278                         uint16_t id = 65535;
 279                         uint64_t timestamp = ctx->tsc;
 280
 281                         lib_ring_buffer_write(config, ctx, &id, sizeof(id));
 282                         /* Align extended struct on largest member */
 283                         lib_ring_buffer_align_ctx(ctx, lttng_alignof(uint64_t));
 284                         lib_ring_buffer_write(config, ctx, &event_id, sizeof(event_id));
 285                         lib_ring_buffer_align_ctx(ctx, lttng_alignof(uint64_t));
 286                         lib_ring_buffer_write(config, ctx, &timestamp, sizeof(timestamp));
 287                 }
 288                 break;
 289         }
 290         default:
 291                 WARN_ON_ONCE(1);
 292         }
 293         ctx_record(ctx, ltt_chan, ltt_chan->ctx);
 294         ctx_record(ctx, ltt_chan, event->ctx);
 295         lib_ring_buffer_align_ctx(ctx, ctx->largest_align);
 296 }
 297
 298 static const struct lttng_ust_lib_ring_buffer_config client_config;
 299
 300 static uint64_t client_ring_buffer_clock_read(struct channel *chan)
 301 {
 302         return lib_ring_buffer_clock_read(chan);
 303 }
 304
 305 static
 306 size_t client_record_header_size(const struct lttng_ust_lib_ring_buffer_config *config,
 307                                  struct channel *chan, size_t offset,
 308                                  size_t *pre_header_padding,
 309                                  struct lttng_ust_lib_ring_buffer_ctx *ctx)
 310 {
 311         return record_header_size(config, chan, offset,
 312                                   pre_header_padding, ctx);
 313 }
 314
 315 /**
 316  * client_packet_header_size - called on buffer-switch to a new sub-buffer
 317  *
 318  * Return header size without padding after the structure. Don't use packed
 319  * structure because gcc generates inefficient code on some architectures
 320  * (powerpc, mips..)
 321  */
 322 static size_t client_packet_header_size(void)
 323 {
 324         return offsetof(struct packet_header, ctx.header_end);
 325 }
 326
 327 static void client_buffer_begin(struct lttng_ust_lib_ring_buffer *buf, uint64_t tsc,
 328                                 unsigned int subbuf_idx,
 329                                 struct lttng_ust_shm_handle *handle)
 330 {
 331         struct channel *chan = shmp(handle, buf->backend.chan);
 332         struct packet_header *header =
 333                 (struct packet_header *)
 334                         lib_ring_buffer_offset_address(&buf->backend,
 335                                 subbuf_idx * chan->backend.subbuf_size,
 336                                 handle);
 337         struct ltt_channel *ltt_chan = channel_get_private(chan);
 338
 339         header->magic = CTF_MAGIC_NUMBER;
 340         memcpy(header->uuid, ltt_chan->uuid, sizeof(ltt_chan->uuid));
 341         header->stream_id = ltt_chan->id;
 342         header->ctx.timestamp_begin = tsc;
 343         header->ctx.timestamp_end = 0;
 344         header->ctx.events_discarded = 0;
 345         header->ctx.content_size = 0xFFFFFFFF; /* for debugging */
 346         header->ctx.packet_size = 0xFFFFFFFF;
 347         header->ctx.cpu_id = buf->backend.cpu;
 348 }
 349
 350 /*
 351  * offset is assumed to never be 0 here : never deliver a completely empty
 352  * subbuffer. data_size is between 1 and subbuf_size.
 353  */
 354 static void client_buffer_end(struct lttng_ust_lib_ring_buffer *buf, uint64_t tsc,
 355                               unsigned int subbuf_idx, unsigned long data_size,
 356                               struct lttng_ust_shm_handle *handle)
 357 {
 358         struct channel *chan = shmp(handle, buf->backend.chan);
 359         struct packet_header *header =
 360                 (struct packet_header *)
 361                         lib_ring_buffer_offset_address(&buf->backend,
 362                                 subbuf_idx * chan->backend.subbuf_size,
 363                                 handle);
 364         unsigned long records_lost = 0;
 365
 366         header->ctx.timestamp_end = tsc;
 367         header->ctx.content_size = data_size * CHAR_BIT;        /* in bits */
 368         header->ctx.packet_size = PAGE_ALIGN(data_size) * CHAR_BIT; /* in bits */
 369         /*
 370          * We do not care about the records lost count, because the metadata
 371          * channel waits and retry.
 372          */
 373         (void) lib_ring_buffer_get_records_lost_full(&client_config, buf);
 374         records_lost += lib_ring_buffer_get_records_lost_wrap(&client_config, buf);
 375         records_lost += lib_ring_buffer_get_records_lost_big(&client_config, buf);
 376         header->ctx.events_discarded = records_lost;
 377 }
 378
 379 static int client_buffer_create(struct lttng_ust_lib_ring_buffer *buf, void *priv,
 380                                 int cpu, const char *name, struct lttng_ust_shm_handle *handle)
 381 {
 382         return 0;
 383 }
 384
 385 static void client_buffer_finalize(struct lttng_ust_lib_ring_buffer *buf, void *priv, int cpu, struct lttng_ust_shm_handle *handle)
 386 {
 387 }
 388
 389 static const struct lttng_ust_lib_ring_buffer_config client_config = {
 390         .cb.ring_buffer_clock_read = client_ring_buffer_clock_read,
 391         .cb.record_header_size = client_record_header_size,
 392         .cb.subbuffer_header_size = client_packet_header_size,
 393         .cb.buffer_begin = client_buffer_begin,
 394         .cb.buffer_end = client_buffer_end,
 395         .cb.buffer_create = client_buffer_create,
 396         .cb.buffer_finalize = client_buffer_finalize,
 397
 398         .tsc_bits = LTTNG_COMPACT_TSC_BITS,
 399         .alloc = RING_BUFFER_ALLOC_PER_CPU,
 400         .sync = RING_BUFFER_SYNC_GLOBAL,
 401         .mode = RING_BUFFER_MODE_TEMPLATE,
 402         .backend = RING_BUFFER_PAGE,
 403         .output = RING_BUFFER_MMAP,
 404         .oops = RING_BUFFER_OOPS_CONSISTENCY,
 405         .ipi = RING_BUFFER_NO_IPI_BARRIER,
 406         .wakeup = RING_BUFFER_WAKEUP_BY_WRITER,
 407         .client_type = LTTNG_CLIENT_TYPE,
 408 };
 409
 410 const struct lttng_ust_lib_ring_buffer_client_cb *LTTNG_CLIENT_CALLBACKS = &client_config.cb;
 411
 412 static
 413 struct ltt_channel *_channel_create(const char *name,
 414                                 void *buf_addr,
 415                                 size_t subbuf_size, size_t num_subbuf,
 416                                 unsigned int switch_timer_interval,
 417                                 unsigned int read_timer_interval,
 418                                 int **shm_fd, int **wait_fd,
 419                                 uint64_t **memory_map_size,
 420                                 struct ltt_channel *chan_priv_init)
 421 {
 422         void *priv;
 423         struct ltt_channel *ltt_chan = NULL;
 424         struct lttng_ust_shm_handle *handle;
 425
 426         handle = channel_create(&client_config, name,
 427                         &priv, __alignof__(*ltt_chan), sizeof(*ltt_chan),
 428                         chan_priv_init,
 429                         buf_addr, subbuf_size, num_subbuf,
 430                         switch_timer_interval, read_timer_interval,
 431                         shm_fd, wait_fd, 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, int **wait_fd,
 450                                              uint64_t **memory_map_size)
 451 {
 452         struct lttng_ust_lib_ring_buffer *buf;
 453         int cpu;
 454
 455         for_each_channel_cpu(cpu, chan) {
 456                 buf = channel_get_ring_buffer(&client_config, chan,
 457                                 cpu, handle, shm_fd, wait_fd,
 458                                 memory_map_size);
 459                 if (!lib_ring_buffer_open_read(buf, handle, 0))
 460                         return buf;
 461         }
 462         return NULL;
 463 }
 464
 465 static
 466 void ltt_buffer_read_close(struct lttng_ust_lib_ring_buffer *buf,
 467                            struct lttng_ust_shm_handle *handle)
 468 {
 469         lib_ring_buffer_release_read(buf, handle, 0);
 470 }
 471
 472 static
 473 int ltt_event_reserve(struct lttng_ust_lib_ring_buffer_ctx *ctx,
 474                       uint32_t event_id)
 475 {
 476         struct ltt_channel *ltt_chan = channel_get_private(ctx->chan);
 477         int ret, cpu;
 478
 479         cpu = lib_ring_buffer_get_cpu(&client_config);
 480         if (cpu < 0)
 481                 return -EPERM;
 482         ctx->cpu = cpu;
 483
 484         switch (ltt_chan->header_type) {
 485         case 1: /* compact */
 486                 if (event_id > 30)
 487                         ctx->rflags |= LTT_RFLAG_EXTENDED;
 488                 break;
 489         case 2: /* large */
 490                 if (event_id > 65534)
 491                         ctx->rflags |= LTT_RFLAG_EXTENDED;
 492                 break;
 493         default:
 494                 WARN_ON_ONCE(1);
 495         }
 496
 497         ret = lib_ring_buffer_reserve(&client_config, ctx);
 498         if (ret)
 499                 goto put;
 500         ltt_write_event_header(&client_config, ctx, event_id);
 501         return 0;
 502 put:
 503         lib_ring_buffer_put_cpu(&client_config);
 504         return ret;
 505 }
 506
 507 static
 508 void ltt_event_commit(struct lttng_ust_lib_ring_buffer_ctx *ctx)
 509 {
 510         lib_ring_buffer_commit(&client_config, ctx);
 511         lib_ring_buffer_put_cpu(&client_config);
 512 }
 513
 514 static
 515 void ltt_event_write(struct lttng_ust_lib_ring_buffer_ctx *ctx, const void *src,
 516                      size_t len)
 517 {
 518         lib_ring_buffer_write(&client_config, ctx, src, len);
 519 }
 520
 521 #if 0
 522 static
 523 wait_queue_head_t *ltt_get_reader_wait_queue(struct channel *chan)
 524 {
 525         return &chan->read_wait;
 526 }
 527
 528 static
 529 wait_queue_head_t *ltt_get_hp_wait_queue(struct channel *chan)
 530 {
 531         return &chan->hp_wait;
 532 }
 533 #endif //0
 534
 535 static
 536 int ltt_is_finalized(struct channel *chan)
 537 {
 538         return lib_ring_buffer_channel_is_finalized(chan);
 539 }
 540
 541 static
 542 int ltt_is_disabled(struct channel *chan)
 543 {
 544         return lib_ring_buffer_channel_is_disabled(chan);
 545 }
 546
 547 static
 548 int ltt_flush_buffer(struct channel *chan, struct lttng_ust_shm_handle *handle)
 549 {
 550         struct lttng_ust_lib_ring_buffer *buf;
 551         int cpu;
 552
 553         for_each_channel_cpu(cpu, chan) {
 554                 int *shm_fd, *wait_fd;
 555                 uint64_t *memory_map_size;
 556
 557                 buf = channel_get_ring_buffer(&client_config, chan,
 558                                 cpu, handle, &shm_fd, &wait_fd,
 559                                 &memory_map_size);
 560                 lib_ring_buffer_switch(&client_config, buf,
 561                                 SWITCH_ACTIVE, handle);
 562         }
 563         return 0;
 564 }
 565
 566 static struct ltt_transport ltt_relay_transport = {
 567         .name = "relay-" RING_BUFFER_MODE_TEMPLATE_STRING "-mmap",
 568         .ops = {
 569                 .channel_create = _channel_create,
 570                 .channel_destroy = ltt_channel_destroy,
 571                 .buffer_read_open = ltt_buffer_read_open,
 572                 .buffer_read_close = ltt_buffer_read_close,
 573                 .event_reserve = ltt_event_reserve,
 574                 .event_commit = ltt_event_commit,
 575                 .event_write = ltt_event_write,
 576                 .packet_avail_size = NULL,      /* Would be racy anyway */
 577                 //.get_reader_wait_queue = ltt_get_reader_wait_queue,
 578                 //.get_hp_wait_queue = ltt_get_hp_wait_queue,
 579                 .is_finalized = ltt_is_finalized,
 580                 .is_disabled = ltt_is_disabled,
 581                 .flush_buffer = ltt_flush_buffer,
 582         },
 583 };
 584
 585 void RING_BUFFER_MODE_TEMPLATE_INIT(void)
 586 {
 587         DBG("LTT : ltt ring buffer client init\n");
 588         ltt_transport_register(&ltt_relay_transport);
 589 }
 590
 591 void RING_BUFFER_MODE_TEMPLATE_EXIT(void)
 592 {
 593         DBG("LTT : ltt ring buffer client exit\n");
 594         ltt_transport_unregister(&ltt_relay_transport);
 595 }