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
  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                 uint64_t content_size;          /* Size of data in subbuffer */
  54                 uint64_t packet_size;           /* Subbuffer size (include padding) */
  55                 unsigned long events_discarded; /*
  56                                                  * Events lost in this subbuffer since
  57                                                  * the beginning of the trace.
  58                                                  * (may overflow)
  59                                                  */
  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         offset += lib_ring_buffer_align(offset, ctx->largest_align);
  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 lttng_channel *chan,
  88                 struct lttng_ctx *ctx)
  89 {
  90         int i;
  91
  92         if (caa_likely(!ctx))
  93                 return;
  94         lib_ring_buffer_align_ctx(bufctx, ctx->largest_align);
  95         for (i = 0; i < ctx->nr_fields; i++)
  96                 ctx->fields[i].record(&ctx->fields[i], bufctx, chan);
  97 }
  98
  99 /*
 100  * record_header_size - Calculate the header size and padding necessary.
 101  * @config: ring buffer instance configuration
 102  * @chan: channel
 103  * @offset: offset in the write buffer
 104  * @pre_header_padding: padding to add before the header (output)
 105  * @ctx: reservation context
 106  *
 107  * Returns the event header size (including padding).
 108  *
 109  * The payload must itself determine its own alignment from the biggest type it
 110  * contains.
 111  */
 112 static __inline__
 113 unsigned char record_header_size(const struct lttng_ust_lib_ring_buffer_config *config,
 114                                  struct channel *chan, size_t offset,
 115                                  size_t *pre_header_padding,
 116                                  struct lttng_ust_lib_ring_buffer_ctx *ctx)
 117 {
 118         struct lttng_channel *lttng_chan = channel_get_private(chan);
 119         struct lttng_event *event = ctx->priv;
 120         size_t orig_offset = offset;
 121         size_t padding;
 122
 123         switch (lttng_chan->header_type) {
 124         case 1: /* compact */
 125                 padding = lib_ring_buffer_align(offset, lttng_alignof(uint32_t));
 126                 offset += padding;
 127                 if (!(ctx->rflags & (RING_BUFFER_RFLAG_FULL_TSC | LTTNG_RFLAG_EXTENDED))) {
 128                         offset += sizeof(uint32_t);     /* id and timestamp */
 129                 } else {
 130                         /* Minimum space taken by LTTNG_COMPACT_EVENT_BITS id */
 131                         offset += (LTTNG_COMPACT_EVENT_BITS + CHAR_BIT - 1) / CHAR_BIT;
 132                         /* Align extended struct on largest member */
 133                         offset += lib_ring_buffer_align(offset, lttng_alignof(uint64_t));
 134                         offset += sizeof(uint32_t);     /* id */
 135                         offset += lib_ring_buffer_align(offset, lttng_alignof(uint64_t));
 136                         offset += sizeof(uint64_t);     /* timestamp */
 137                 }
 138                 break;
 139         case 2: /* large */
 140                 padding = lib_ring_buffer_align(offset, lttng_alignof(uint16_t));
 141                 offset += padding;
 142                 offset += sizeof(uint16_t);
 143                 if (!(ctx->rflags & (RING_BUFFER_RFLAG_FULL_TSC | LTTNG_RFLAG_EXTENDED))) {
 144                         offset += lib_ring_buffer_align(offset, lttng_alignof(uint32_t));
 145                         offset += sizeof(uint32_t);     /* timestamp */
 146                 } else {
 147                         /* Align extended struct on largest member */
 148                         offset += lib_ring_buffer_align(offset, lttng_alignof(uint64_t));
 149                         offset += sizeof(uint32_t);     /* id */
 150                         offset += lib_ring_buffer_align(offset, lttng_alignof(uint64_t));
 151                         offset += sizeof(uint64_t);     /* timestamp */
 152                 }
 153                 break;
 154         default:
 155                 padding = 0;
 156                 WARN_ON_ONCE(1);
 157         }
 158         offset += ctx_get_size(offset, event->ctx);
 159         offset += ctx_get_size(offset, lttng_chan->ctx);
 160
 161         *pre_header_padding = padding;
 162         return offset - orig_offset;
 163 }
 164
 165 #include "../libringbuffer/api.h"
 166 #include "lttng-rb-clients.h"
 167
 168 static
 169 void lttng_write_event_header_slow(const struct lttng_ust_lib_ring_buffer_config *config,
 170                                  struct lttng_ust_lib_ring_buffer_ctx *ctx,
 171                                  uint32_t event_id);
 172
 173 /*
 174  * lttng_write_event_header
 175  *
 176  * Writes the event header to the offset (already aligned on 32-bits).
 177  *
 178  * @config: ring buffer instance configuration
 179  * @ctx: reservation context
 180  * @event_id: event ID
 181  */
 182 static __inline__
 183 void lttng_write_event_header(const struct lttng_ust_lib_ring_buffer_config *config,
 184                             struct lttng_ust_lib_ring_buffer_ctx *ctx,
 185                             uint32_t event_id)
 186 {
 187         struct lttng_channel *lttng_chan = channel_get_private(ctx->chan);
 188         struct lttng_event *event = ctx->priv;
 189
 190         if (caa_unlikely(ctx->rflags))
 191                 goto slow_path;
 192
 193         switch (lttng_chan->header_type) {
 194         case 1: /* compact */
 195         {
 196                 uint32_t id_time = 0;
 197
 198                 bt_bitfield_write(&id_time, uint32_t,
 199                                 0,
 200                                 LTTNG_COMPACT_EVENT_BITS,
 201                                 event_id);
 202                 bt_bitfield_write(&id_time, uint32_t,
 203                                 LTTNG_COMPACT_EVENT_BITS,
 204                                 LTTNG_COMPACT_TSC_BITS,
 205                                 ctx->tsc);
 206                 lib_ring_buffer_write(config, ctx, &id_time, sizeof(id_time));
 207                 break;
 208         }
 209         case 2: /* large */
 210         {
 211                 uint32_t timestamp = (uint32_t) ctx->tsc;
 212                 uint16_t id = event_id;
 213
 214                 lib_ring_buffer_write(config, ctx, &id, sizeof(id));
 215                 lib_ring_buffer_align_ctx(ctx, lttng_alignof(uint32_t));
 216                 lib_ring_buffer_write(config, ctx, &timestamp, sizeof(timestamp));
 217                 break;
 218         }
 219         default:
 220                 WARN_ON_ONCE(1);
 221         }
 222
 223         ctx_record(ctx, lttng_chan, lttng_chan->ctx);
 224         ctx_record(ctx, lttng_chan, event->ctx);
 225         lib_ring_buffer_align_ctx(ctx, ctx->largest_align);
 226
 227         return;
 228
 229 slow_path:
 230         lttng_write_event_header_slow(config, ctx, event_id);
 231 }
 232
 233 static
 234 void lttng_write_event_header_slow(const struct lttng_ust_lib_ring_buffer_config *config,
 235                                  struct lttng_ust_lib_ring_buffer_ctx *ctx,
 236                                  uint32_t event_id)
 237 {
 238         struct lttng_channel *lttng_chan = channel_get_private(ctx->chan);
 239         struct lttng_event *event = ctx->priv;
 240
 241         switch (lttng_chan->header_type) {
 242         case 1: /* compact */
 243                 if (!(ctx->rflags & (RING_BUFFER_RFLAG_FULL_TSC | LTTNG_RFLAG_EXTENDED))) {
 244                         uint32_t id_time = 0;
 245
 246                         bt_bitfield_write(&id_time, uint32_t,
 247                                         0,
 248                                         LTTNG_COMPACT_EVENT_BITS,
 249                                         event_id);
 250                         bt_bitfield_write(&id_time, uint32_t,
 251                                         LTTNG_COMPACT_EVENT_BITS,
 252                                         LTTNG_COMPACT_TSC_BITS,
 253                                         ctx->tsc);
 254                         lib_ring_buffer_write(config, ctx, &id_time, sizeof(id_time));
 255                 } else {
 256                         uint8_t id = 0;
 257                         uint64_t timestamp = ctx->tsc;
 258
 259                         bt_bitfield_write(&id, uint8_t,
 260                                         0,
 261                                         LTTNG_COMPACT_EVENT_BITS,
 262                                         31);
 263                         lib_ring_buffer_write(config, ctx, &id, sizeof(id));
 264                         /* Align extended struct on largest member */
 265                         lib_ring_buffer_align_ctx(ctx, lttng_alignof(uint64_t));
 266                         lib_ring_buffer_write(config, ctx, &event_id, sizeof(event_id));
 267                         lib_ring_buffer_align_ctx(ctx, lttng_alignof(uint64_t));
 268                         lib_ring_buffer_write(config, ctx, &timestamp, sizeof(timestamp));
 269                 }
 270                 break;
 271         case 2: /* large */
 272         {
 273                 if (!(ctx->rflags & (RING_BUFFER_RFLAG_FULL_TSC | LTTNG_RFLAG_EXTENDED))) {
 274                         uint32_t timestamp = (uint32_t) ctx->tsc;
 275                         uint16_t id = event_id;
 276
 277                         lib_ring_buffer_write(config, ctx, &id, sizeof(id));
 278                         lib_ring_buffer_align_ctx(ctx, lttng_alignof(uint32_t));
 279                         lib_ring_buffer_write(config, ctx, &timestamp, sizeof(timestamp));
 280                 } else {
 281                         uint16_t id = 65535;
 282                         uint64_t timestamp = ctx->tsc;
 283
 284                         lib_ring_buffer_write(config, ctx, &id, sizeof(id));
 285                         /* Align extended struct on largest member */
 286                         lib_ring_buffer_align_ctx(ctx, lttng_alignof(uint64_t));
 287                         lib_ring_buffer_write(config, ctx, &event_id, sizeof(event_id));
 288                         lib_ring_buffer_align_ctx(ctx, lttng_alignof(uint64_t));
 289                         lib_ring_buffer_write(config, ctx, &timestamp, sizeof(timestamp));
 290                 }
 291                 break;
 292         }
 293         default:
 294                 WARN_ON_ONCE(1);
 295         }
 296         ctx_record(ctx, lttng_chan, lttng_chan->ctx);
 297         ctx_record(ctx, lttng_chan, event->ctx);
 298         lib_ring_buffer_align_ctx(ctx, ctx->largest_align);
 299 }
 300
 301 static const struct lttng_ust_lib_ring_buffer_config client_config;
 302
 303 static uint64_t client_ring_buffer_clock_read(struct channel *chan)
 304 {
 305         return lib_ring_buffer_clock_read(chan);
 306 }
 307
 308 static
 309 size_t client_record_header_size(const struct lttng_ust_lib_ring_buffer_config *config,
 310                                  struct channel *chan, size_t offset,
 311                                  size_t *pre_header_padding,
 312                                  struct lttng_ust_lib_ring_buffer_ctx *ctx)
 313 {
 314         return record_header_size(config, chan, offset,
 315                                   pre_header_padding, ctx);
 316 }
 317
 318 /**
 319  * client_packet_header_size - called on buffer-switch to a new sub-buffer
 320  *
 321  * Return header size without padding after the structure. Don't use packed
 322  * structure because gcc generates inefficient code on some architectures
 323  * (powerpc, mips..)
 324  */
 325 static size_t client_packet_header_size(void)
 326 {
 327         return offsetof(struct packet_header, ctx.header_end);
 328 }
 329
 330 static void client_buffer_begin(struct lttng_ust_lib_ring_buffer *buf, uint64_t tsc,
 331                                 unsigned int subbuf_idx,
 332                                 struct lttng_ust_shm_handle *handle)
 333 {
 334         struct channel *chan = shmp(handle, buf->backend.chan);
 335         struct packet_header *header =
 336                 (struct packet_header *)
 337                         lib_ring_buffer_offset_address(&buf->backend,
 338                                 subbuf_idx * chan->backend.subbuf_size,
 339                                 handle);
 340         struct lttng_channel *lttng_chan = channel_get_private(chan);
 341
 342         header->magic = CTF_MAGIC_NUMBER;
 343         memcpy(header->uuid, lttng_chan->uuid, sizeof(lttng_chan->uuid));
 344         header->stream_id = lttng_chan->id;
 345         header->ctx.timestamp_begin = tsc;
 346         header->ctx.timestamp_end = 0;
 347         header->ctx.content_size = ~0ULL; /* for debugging */
 348         header->ctx.packet_size = ~0ULL;
 349         header->ctx.events_discarded = 0;
 350         header->ctx.cpu_id = buf->backend.cpu;
 351 }
 352
 353 /*
 354  * offset is assumed to never be 0 here : never deliver a completely empty
 355  * subbuffer. data_size is between 1 and subbuf_size.
 356  */
 357 static void client_buffer_end(struct lttng_ust_lib_ring_buffer *buf, uint64_t tsc,
 358                               unsigned int subbuf_idx, unsigned long data_size,
 359                               struct lttng_ust_shm_handle *handle)
 360 {
 361         struct channel *chan = shmp(handle, buf->backend.chan);
 362         struct packet_header *header =
 363                 (struct packet_header *)
 364                         lib_ring_buffer_offset_address(&buf->backend,
 365                                 subbuf_idx * chan->backend.subbuf_size,
 366                                 handle);
 367         unsigned long records_lost = 0;
 368
 369         header->ctx.timestamp_end = tsc;
 370         header->ctx.content_size =
 371                 (uint64_t) data_size * CHAR_BIT;                /* in bits */
 372         header->ctx.packet_size =
 373                 (uint64_t) PAGE_ALIGN(data_size) * CHAR_BIT;    /* in bits */
 374
 375         records_lost += lib_ring_buffer_get_records_lost_full(&client_config, buf);
 376         records_lost += lib_ring_buffer_get_records_lost_wrap(&client_config, buf);
 377         records_lost += lib_ring_buffer_get_records_lost_big(&client_config, buf);
 378         header->ctx.events_discarded = records_lost;
 379 }
 380
 381 static int client_buffer_create(struct lttng_ust_lib_ring_buffer *buf, void *priv,
 382                                 int cpu, const char *name, struct lttng_ust_shm_handle *handle)
 383 {
 384         return 0;
 385 }
 386
 387 static void client_buffer_finalize(struct lttng_ust_lib_ring_buffer *buf, void *priv, int cpu, struct lttng_ust_shm_handle *handle)
 388 {
 389 }
 390
 391 static struct packet_header *client_packet_header(struct lttng_ust_lib_ring_buffer *buf,
 392                 struct lttng_ust_shm_handle *handle)
 393 {
 394         return lib_ring_buffer_read_offset_address(&buf->backend, 0, handle);
 395 }
 396
 397 static int client_timestamp_begin(struct lttng_ust_lib_ring_buffer *buf,
 398                 struct lttng_ust_shm_handle *handle,
 399                 uint64_t *timestamp_begin)
 400 {
 401         struct packet_header *header;
 402
 403         header = client_packet_header(buf, handle);
 404         *timestamp_begin = header->ctx.timestamp_begin;
 405         return 0;
 406 }
 407
 408 static int client_timestamp_end(struct lttng_ust_lib_ring_buffer *buf,
 409                 struct lttng_ust_shm_handle *handle,
 410                 uint64_t *timestamp_end)
 411 {
 412         struct packet_header *header;
 413
 414         header = client_packet_header(buf, handle);
 415         *timestamp_end = header->ctx.timestamp_end;
 416         return 0;
 417 }
 418
 419 static int client_events_discarded(struct lttng_ust_lib_ring_buffer *buf,
 420                 struct lttng_ust_shm_handle *handle,
 421                 uint64_t *events_discarded)
 422 {
 423         struct packet_header *header;
 424
 425         header = client_packet_header(buf, handle);
 426         *events_discarded = header->ctx.events_discarded;
 427         return 0;
 428 }
 429
 430 static int client_content_size(struct lttng_ust_lib_ring_buffer *buf,
 431                 struct lttng_ust_shm_handle *handle,
 432                 uint64_t *content_size)
 433 {
 434         struct packet_header *header;
 435
 436         header = client_packet_header(buf, handle);
 437         *content_size = header->ctx.content_size;
 438         return 0;
 439 }
 440
 441 static int client_packet_size(struct lttng_ust_lib_ring_buffer *buf,
 442                 struct lttng_ust_shm_handle *handle,
 443                 uint64_t *packet_size)
 444 {
 445         struct packet_header *header;
 446
 447         header = client_packet_header(buf, handle);
 448         *packet_size = header->ctx.packet_size;
 449         return 0;
 450 }
 451
 452 static int client_stream_id(struct lttng_ust_lib_ring_buffer *buf,
 453                 struct lttng_ust_shm_handle *handle,
 454                 uint64_t *stream_id)
 455 {
 456         struct packet_header *header;
 457
 458         header = client_packet_header(buf, handle);
 459         *stream_id = header->stream_id;
 460         return 0;
 461 }
 462
 463 static int client_current_timestamp(struct lttng_ust_lib_ring_buffer *buf,
 464                 struct lttng_ust_shm_handle *handle,
 465                 uint64_t *ts)
 466 {
 467         struct channel *chan;
 468
 469         chan = shmp(handle, handle->chan);
 470         *ts = client_ring_buffer_clock_read(chan);
 471
 472         return 0;
 473 }
 474
 475 static const
 476 struct lttng_ust_client_lib_ring_buffer_client_cb client_cb = {
 477         .parent = {
 478                 .ring_buffer_clock_read = client_ring_buffer_clock_read,
 479                 .record_header_size = client_record_header_size,
 480                 .subbuffer_header_size = client_packet_header_size,
 481                 .buffer_begin = client_buffer_begin,
 482                 .buffer_end = client_buffer_end,
 483                 .buffer_create = client_buffer_create,
 484                 .buffer_finalize = client_buffer_finalize,
 485         },
 486         .timestamp_begin = client_timestamp_begin,
 487         .timestamp_end = client_timestamp_end,
 488         .events_discarded = client_events_discarded,
 489         .content_size = client_content_size,
 490         .packet_size = client_packet_size,
 491         .stream_id = client_stream_id,
 492         .current_timestamp = client_current_timestamp,
 493 };
 494
 495 static const struct lttng_ust_lib_ring_buffer_config client_config = {
 496         .cb.ring_buffer_clock_read = client_ring_buffer_clock_read,
 497         .cb.record_header_size = client_record_header_size,
 498         .cb.subbuffer_header_size = client_packet_header_size,
 499         .cb.buffer_begin = client_buffer_begin,
 500         .cb.buffer_end = client_buffer_end,
 501         .cb.buffer_create = client_buffer_create,
 502         .cb.buffer_finalize = client_buffer_finalize,
 503
 504         .tsc_bits = LTTNG_COMPACT_TSC_BITS,
 505         .alloc = RING_BUFFER_ALLOC_PER_CPU,
 506         .sync = RING_BUFFER_SYNC_GLOBAL,
 507         .mode = RING_BUFFER_MODE_TEMPLATE,
 508         .backend = RING_BUFFER_PAGE,
 509         .output = RING_BUFFER_MMAP,
 510         .oops = RING_BUFFER_OOPS_CONSISTENCY,
 511         .ipi = RING_BUFFER_NO_IPI_BARRIER,
 512         .wakeup = LTTNG_CLIENT_WAKEUP,
 513         .client_type = LTTNG_CLIENT_TYPE,
 514
 515         .cb_ptr = &client_cb.parent,
 516 };
 517
 518 const struct lttng_ust_client_lib_ring_buffer_client_cb *LTTNG_CLIENT_CALLBACKS = &client_cb;
 519
 520 static
 521 struct lttng_channel *_channel_create(const char *name,
 522                                 void *buf_addr,
 523                                 size_t subbuf_size, size_t num_subbuf,
 524                                 unsigned int switch_timer_interval,
 525                                 unsigned int read_timer_interval,
 526                                 unsigned char *uuid,
 527                                 uint32_t chan_id)
 528 {
 529         struct lttng_channel chan_priv_init;
 530         struct lttng_ust_shm_handle *handle;
 531         struct lttng_channel *lttng_chan;
 532         void *priv;
 533
 534         memset(&chan_priv_init, 0, sizeof(chan_priv_init));
 535         memcpy(chan_priv_init.uuid, uuid, LTTNG_UST_UUID_LEN);
 536         chan_priv_init.id = chan_id;
 537         handle = channel_create(&client_config, name,
 538                         &priv, __alignof__(struct lttng_channel),
 539                         sizeof(struct lttng_channel),
 540                         &chan_priv_init,
 541                         buf_addr, subbuf_size, num_subbuf,
 542                         switch_timer_interval, read_timer_interval);
 543         if (!handle)
 544                 return NULL;
 545         lttng_chan = priv;
 546         lttng_chan->handle = handle;
 547         lttng_chan->chan = shmp(handle, handle->chan);
 548         return lttng_chan;
 549 }
 550
 551 static
 552 void lttng_channel_destroy(struct lttng_channel *chan)
 553 {
 554         channel_destroy(chan->chan, chan->handle, 1);
 555 }
 556
 557 static
 558 int lttng_event_reserve(struct lttng_ust_lib_ring_buffer_ctx *ctx,
 559                       uint32_t event_id)
 560 {
 561         struct lttng_channel *lttng_chan = channel_get_private(ctx->chan);
 562         int ret, cpu;
 563
 564         cpu = lib_ring_buffer_get_cpu(&client_config);
 565         if (cpu < 0)
 566                 return -EPERM;
 567         ctx->cpu = cpu;
 568
 569         switch (lttng_chan->header_type) {
 570         case 1: /* compact */
 571                 if (event_id > 30)
 572                         ctx->rflags |= LTTNG_RFLAG_EXTENDED;
 573                 break;
 574         case 2: /* large */
 575                 if (event_id > 65534)
 576                         ctx->rflags |= LTTNG_RFLAG_EXTENDED;
 577                 break;
 578         default:
 579                 WARN_ON_ONCE(1);
 580         }
 581
 582         ret = lib_ring_buffer_reserve(&client_config, ctx);
 583         if (ret)
 584                 goto put;
 585         lttng_write_event_header(&client_config, ctx, event_id);
 586         return 0;
 587 put:
 588         lib_ring_buffer_put_cpu(&client_config);
 589         return ret;
 590 }
 591
 592 static
 593 void lttng_event_commit(struct lttng_ust_lib_ring_buffer_ctx *ctx)
 594 {
 595         lib_ring_buffer_commit(&client_config, ctx);
 596         lib_ring_buffer_put_cpu(&client_config);
 597 }
 598
 599 static
 600 void lttng_event_write(struct lttng_ust_lib_ring_buffer_ctx *ctx, const void *src,
 601                      size_t len)
 602 {
 603         lib_ring_buffer_write(&client_config, ctx, src, len);
 604 }
 605
 606 static
 607 void lttng_event_strcpy(struct lttng_ust_lib_ring_buffer_ctx *ctx, const char *src,
 608                      size_t len)
 609 {
 610         lib_ring_buffer_strcpy(&client_config, ctx, src, len, '#');
 611 }
 612
 613 #if 0
 614 static
 615 wait_queue_head_t *lttng_get_reader_wait_queue(struct channel *chan)
 616 {
 617         return &chan->read_wait;
 618 }
 619
 620 static
 621 wait_queue_head_t *lttng_get_hp_wait_queue(struct channel *chan)
 622 {
 623         return &chan->hp_wait;
 624 }
 625 #endif //0
 626
 627 static
 628 int lttng_is_finalized(struct channel *chan)
 629 {
 630         return lib_ring_buffer_channel_is_finalized(chan);
 631 }
 632
 633 static
 634 int lttng_is_disabled(struct channel *chan)
 635 {
 636         return lib_ring_buffer_channel_is_disabled(chan);
 637 }
 638
 639 static
 640 int lttng_flush_buffer(struct channel *chan, struct lttng_ust_shm_handle *handle)
 641 {
 642         struct lttng_ust_lib_ring_buffer *buf;
 643         int cpu;
 644
 645         for_each_channel_cpu(cpu, chan) {
 646                 int shm_fd, wait_fd, wakeup_fd;
 647                 uint64_t memory_map_size;
 648
 649                 buf = channel_get_ring_buffer(&client_config, chan,
 650                                 cpu, handle, &shm_fd, &wait_fd,
 651                                 &wakeup_fd, &memory_map_size);
 652                 lib_ring_buffer_switch(&client_config, buf,
 653                                 SWITCH_ACTIVE, handle);
 654         }
 655         return 0;
 656 }
 657
 658 static struct lttng_transport lttng_relay_transport = {
 659         .name = "relay-" RING_BUFFER_MODE_TEMPLATE_STRING "-mmap",
 660         .ops = {
 661                 .channel_create = _channel_create,
 662                 .channel_destroy = lttng_channel_destroy,
 663                 .u.has_strcpy = 1,
 664                 .event_reserve = lttng_event_reserve,
 665                 .event_commit = lttng_event_commit,
 666                 .event_write = lttng_event_write,
 667                 .packet_avail_size = NULL,      /* Would be racy anyway */
 668                 //.get_reader_wait_queue = lttng_get_reader_wait_queue,
 669                 //.get_hp_wait_queue = lttng_get_hp_wait_queue,
 670                 .is_finalized = lttng_is_finalized,
 671                 .is_disabled = lttng_is_disabled,
 672                 .flush_buffer = lttng_flush_buffer,
 673                 .event_strcpy = lttng_event_strcpy,
 674         },
 675         .client_config = &client_config,
 676 };
 677
 678 void RING_BUFFER_MODE_TEMPLATE_INIT(void)
 679 {
 680         DBG("LTT : ltt ring buffer client \"%s\" init\n",
 681                 "relay-" RING_BUFFER_MODE_TEMPLATE_STRING "-mmap");
 682         lttng_transport_register(&lttng_relay_transport);
 683 }
 684
 685 void RING_BUFFER_MODE_TEMPLATE_EXIT(void)
 686 {
 687         DBG("LTT : ltt ring buffer client \"%s\" exit\n",
 688                 "relay-" RING_BUFFER_MODE_TEMPLATE_STRING "-mmap");
 689         lttng_transport_unregister(&lttng_relay_transport);
 690 }