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 void client_content_size_field(const struct lttng_ust_lib_ring_buffer_config *config,
 392                                       size_t *offset, size_t *length)
 393 {
 394         *offset = offsetof(struct packet_header, ctx.content_size);
 395         *length = sizeof(((struct packet_header *) NULL)->ctx.content_size);
 396 }
 397
 398 static void client_packet_size_field(const struct lttng_ust_lib_ring_buffer_config *config,
 399                                       size_t *offset, size_t *length)
 400 {
 401         *offset = offsetof(struct packet_header, ctx.packet_size);
 402         *length = sizeof(((struct packet_header *) NULL)->ctx.packet_size);
 403 }
 404
 405 static struct packet_header *client_packet_header(struct lttng_ust_lib_ring_buffer *buf,
 406                 struct lttng_ust_shm_handle *handle)
 407 {
 408         return lib_ring_buffer_read_offset_address(&buf->backend, 0, handle);
 409 }
 410
 411 static int client_timestamp_begin(struct lttng_ust_lib_ring_buffer *buf,
 412                 struct lttng_ust_shm_handle *handle,
 413                 uint64_t *timestamp_begin)
 414 {
 415         struct packet_header *header;
 416
 417         header = client_packet_header(buf, handle);
 418         *timestamp_begin = header->ctx.timestamp_begin;
 419         return 0;
 420 }
 421
 422 static int client_timestamp_end(struct lttng_ust_lib_ring_buffer *buf,
 423                 struct lttng_ust_shm_handle *handle,
 424                 uint64_t *timestamp_end)
 425 {
 426         struct packet_header *header;
 427
 428         header = client_packet_header(buf, handle);
 429         *timestamp_end = header->ctx.timestamp_end;
 430         return 0;
 431 }
 432
 433 static int client_events_discarded(struct lttng_ust_lib_ring_buffer *buf,
 434                 struct lttng_ust_shm_handle *handle,
 435                 uint64_t *events_discarded)
 436 {
 437         struct packet_header *header;
 438
 439         header = client_packet_header(buf, handle);
 440         *events_discarded = header->ctx.events_discarded;
 441         return 0;
 442 }
 443
 444 static int client_content_size(struct lttng_ust_lib_ring_buffer *buf,
 445                 struct lttng_ust_shm_handle *handle,
 446                 uint64_t *content_size)
 447 {
 448         struct packet_header *header;
 449
 450         header = client_packet_header(buf, handle);
 451         *content_size = header->ctx.content_size;
 452         return 0;
 453 }
 454
 455 static int client_packet_size(struct lttng_ust_lib_ring_buffer *buf,
 456                 struct lttng_ust_shm_handle *handle,
 457                 uint64_t *packet_size)
 458 {
 459         struct packet_header *header;
 460
 461         header = client_packet_header(buf, handle);
 462         *packet_size = header->ctx.packet_size;
 463         return 0;
 464 }
 465
 466 static int client_stream_id(struct lttng_ust_lib_ring_buffer *buf,
 467                 struct lttng_ust_shm_handle *handle,
 468                 uint64_t *stream_id)
 469 {
 470         struct packet_header *header;
 471
 472         header = client_packet_header(buf, handle);
 473         *stream_id = header->stream_id;
 474         return 0;
 475 }
 476
 477 static int client_current_timestamp(struct lttng_ust_lib_ring_buffer *buf,
 478                 struct lttng_ust_shm_handle *handle,
 479                 uint64_t *ts)
 480 {
 481         struct channel *chan;
 482
 483         chan = shmp(handle, handle->chan);
 484         *ts = client_ring_buffer_clock_read(chan);
 485
 486         return 0;
 487 }
 488
 489 static const
 490 struct lttng_ust_client_lib_ring_buffer_client_cb client_cb = {
 491         .parent = {
 492                 .ring_buffer_clock_read = client_ring_buffer_clock_read,
 493                 .record_header_size = client_record_header_size,
 494                 .subbuffer_header_size = client_packet_header_size,
 495                 .buffer_begin = client_buffer_begin,
 496                 .buffer_end = client_buffer_end,
 497                 .buffer_create = client_buffer_create,
 498                 .buffer_finalize = client_buffer_finalize,
 499                 .content_size_field = client_content_size_field,
 500                 .packet_size_field = client_packet_size_field,
 501         },
 502         .timestamp_begin = client_timestamp_begin,
 503         .timestamp_end = client_timestamp_end,
 504         .events_discarded = client_events_discarded,
 505         .content_size = client_content_size,
 506         .packet_size = client_packet_size,
 507         .stream_id = client_stream_id,
 508         .current_timestamp = client_current_timestamp,
 509 };
 510
 511 static const struct lttng_ust_lib_ring_buffer_config client_config = {
 512         .cb.ring_buffer_clock_read = client_ring_buffer_clock_read,
 513         .cb.record_header_size = client_record_header_size,
 514         .cb.subbuffer_header_size = client_packet_header_size,
 515         .cb.buffer_begin = client_buffer_begin,
 516         .cb.buffer_end = client_buffer_end,
 517         .cb.buffer_create = client_buffer_create,
 518         .cb.buffer_finalize = client_buffer_finalize,
 519         .cb.content_size_field = client_content_size_field,
 520         .cb.packet_size_field = client_packet_size_field,
 521
 522         .tsc_bits = LTTNG_COMPACT_TSC_BITS,
 523         .alloc = RING_BUFFER_ALLOC_PER_CPU,
 524         .sync = RING_BUFFER_SYNC_GLOBAL,
 525         .mode = RING_BUFFER_MODE_TEMPLATE,
 526         .backend = RING_BUFFER_PAGE,
 527         .output = RING_BUFFER_MMAP,
 528         .oops = RING_BUFFER_OOPS_CONSISTENCY,
 529         .ipi = RING_BUFFER_NO_IPI_BARRIER,
 530         .wakeup = LTTNG_CLIENT_WAKEUP,
 531         .client_type = LTTNG_CLIENT_TYPE,
 532
 533         .cb_ptr = &client_cb.parent,
 534 };
 535
 536 const struct lttng_ust_client_lib_ring_buffer_client_cb *LTTNG_CLIENT_CALLBACKS = &client_cb;
 537
 538 static
 539 struct lttng_channel *_channel_create(const char *name,
 540                                 void *buf_addr,
 541                                 size_t subbuf_size, size_t num_subbuf,
 542                                 unsigned int switch_timer_interval,
 543                                 unsigned int read_timer_interval,
 544                                 unsigned char *uuid,
 545                                 uint32_t chan_id,
 546                                 const char *shm_path)
 547 {
 548         struct lttng_channel chan_priv_init;
 549         struct lttng_ust_shm_handle *handle;
 550         struct lttng_channel *lttng_chan;
 551         void *priv;
 552
 553         memset(&chan_priv_init, 0, sizeof(chan_priv_init));
 554         memcpy(chan_priv_init.uuid, uuid, LTTNG_UST_UUID_LEN);
 555         chan_priv_init.id = chan_id;
 556         handle = channel_create(&client_config, name,
 557                         &priv, __alignof__(struct lttng_channel),
 558                         sizeof(struct lttng_channel),
 559                         &chan_priv_init,
 560                         buf_addr, subbuf_size, num_subbuf,
 561                         switch_timer_interval, read_timer_interval,
 562                         shm_path);
 563         if (!handle)
 564                 return NULL;
 565         lttng_chan = priv;
 566         lttng_chan->handle = handle;
 567         lttng_chan->chan = shmp(handle, handle->chan);
 568         return lttng_chan;
 569 }
 570
 571 static
 572 void lttng_channel_destroy(struct lttng_channel *chan)
 573 {
 574         channel_destroy(chan->chan, chan->handle, 1);
 575 }
 576
 577 static
 578 int lttng_event_reserve(struct lttng_ust_lib_ring_buffer_ctx *ctx,
 579                       uint32_t event_id)
 580 {
 581         struct lttng_channel *lttng_chan = channel_get_private(ctx->chan);
 582         int ret, cpu;
 583
 584         cpu = lib_ring_buffer_get_cpu(&client_config);
 585         if (cpu < 0)
 586                 return -EPERM;
 587         ctx->cpu = cpu;
 588
 589         switch (lttng_chan->header_type) {
 590         case 1: /* compact */
 591                 if (event_id > 30)
 592                         ctx->rflags |= LTTNG_RFLAG_EXTENDED;
 593                 break;
 594         case 2: /* large */
 595                 if (event_id > 65534)
 596                         ctx->rflags |= LTTNG_RFLAG_EXTENDED;
 597                 break;
 598         default:
 599                 WARN_ON_ONCE(1);
 600         }
 601
 602         ret = lib_ring_buffer_reserve(&client_config, ctx);
 603         if (ret)
 604                 goto put;
 605         lttng_write_event_header(&client_config, ctx, event_id);
 606         return 0;
 607 put:
 608         lib_ring_buffer_put_cpu(&client_config);
 609         return ret;
 610 }
 611
 612 static
 613 void lttng_event_commit(struct lttng_ust_lib_ring_buffer_ctx *ctx)
 614 {
 615         lib_ring_buffer_commit(&client_config, ctx);
 616         lib_ring_buffer_put_cpu(&client_config);
 617 }
 618
 619 static
 620 void lttng_event_write(struct lttng_ust_lib_ring_buffer_ctx *ctx, const void *src,
 621                      size_t len)
 622 {
 623         lib_ring_buffer_write(&client_config, ctx, src, len);
 624 }
 625
 626 static
 627 void lttng_event_strcpy(struct lttng_ust_lib_ring_buffer_ctx *ctx, const char *src,
 628                      size_t len)
 629 {
 630         lib_ring_buffer_strcpy(&client_config, ctx, src, len, '#');
 631 }
 632
 633 #if 0
 634 static
 635 wait_queue_head_t *lttng_get_reader_wait_queue(struct channel *chan)
 636 {
 637         return &chan->read_wait;
 638 }
 639
 640 static
 641 wait_queue_head_t *lttng_get_hp_wait_queue(struct channel *chan)
 642 {
 643         return &chan->hp_wait;
 644 }
 645 #endif //0
 646
 647 static
 648 int lttng_is_finalized(struct channel *chan)
 649 {
 650         return lib_ring_buffer_channel_is_finalized(chan);
 651 }
 652
 653 static
 654 int lttng_is_disabled(struct channel *chan)
 655 {
 656         return lib_ring_buffer_channel_is_disabled(chan);
 657 }
 658
 659 static
 660 int lttng_flush_buffer(struct channel *chan, struct lttng_ust_shm_handle *handle)
 661 {
 662         struct lttng_ust_lib_ring_buffer *buf;
 663         int cpu;
 664
 665         for_each_channel_cpu(cpu, chan) {
 666                 int shm_fd, wait_fd, wakeup_fd;
 667                 uint64_t memory_map_size;
 668
 669                 buf = channel_get_ring_buffer(&client_config, chan,
 670                                 cpu, handle, &shm_fd, &wait_fd,
 671                                 &wakeup_fd, &memory_map_size);
 672                 lib_ring_buffer_switch(&client_config, buf,
 673                                 SWITCH_ACTIVE, handle);
 674         }
 675         return 0;
 676 }
 677
 678 static struct lttng_transport lttng_relay_transport = {
 679         .name = "relay-" RING_BUFFER_MODE_TEMPLATE_STRING "-mmap",
 680         .ops = {
 681                 .channel_create = _channel_create,
 682                 .channel_destroy = lttng_channel_destroy,
 683                 .u.has_strcpy = 1,
 684                 .event_reserve = lttng_event_reserve,
 685                 .event_commit = lttng_event_commit,
 686                 .event_write = lttng_event_write,
 687                 .packet_avail_size = NULL,      /* Would be racy anyway */
 688                 //.get_reader_wait_queue = lttng_get_reader_wait_queue,
 689                 //.get_hp_wait_queue = lttng_get_hp_wait_queue,
 690                 .is_finalized = lttng_is_finalized,
 691                 .is_disabled = lttng_is_disabled,
 692                 .flush_buffer = lttng_flush_buffer,
 693                 .event_strcpy = lttng_event_strcpy,
 694         },
 695         .client_config = &client_config,
 696 };
 697
 698 void RING_BUFFER_MODE_TEMPLATE_INIT(void)
 699 {
 700         DBG("LTT : ltt ring buffer client \"%s\" init\n",
 701                 "relay-" RING_BUFFER_MODE_TEMPLATE_STRING "-mmap");
 702         lttng_transport_register(&lttng_relay_transport);
 703 }
 704
 705 void RING_BUFFER_MODE_TEMPLATE_EXIT(void)
 706 {
 707         DBG("LTT : ltt ring buffer client \"%s\" exit\n",
 708                 "relay-" RING_BUFFER_MODE_TEMPLATE_STRING "-mmap");
 709         lttng_transport_unregister(&lttng_relay_transport);
 710 }