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(&ctx->fields[i], 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 size_t 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_stack_ctx *lttng_ctx = ctx->priv2;
 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_ctx->chan_ctx);
 224         ctx_record(ctx, lttng_chan, lttng_ctx->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_stack_ctx *lttng_ctx = ctx->priv2;
 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_ctx->chan_ctx);
 297         ctx_record(ctx, lttng_chan, lttng_ctx->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         assert(header);
 343         if (!header)
 344                 return;
 345         header->magic = CTF_MAGIC_NUMBER;
 346         memcpy(header->uuid, lttng_chan->uuid, sizeof(lttng_chan->uuid));
 347         header->stream_id = lttng_chan->id;
 348         header->ctx.timestamp_begin = tsc;
 349         header->ctx.timestamp_end = 0;
 350         header->ctx.content_size = ~0ULL; /* for debugging */
 351         header->ctx.packet_size = ~0ULL;
 352         header->ctx.events_discarded = 0;
 353         header->ctx.cpu_id = buf->backend.cpu;
 354 }
 355
 356 /*
 357  * offset is assumed to never be 0 here : never deliver a completely empty
 358  * subbuffer. data_size is between 1 and subbuf_size.
 359  */
 360 static void client_buffer_end(struct lttng_ust_lib_ring_buffer *buf, uint64_t tsc,
 361                               unsigned int subbuf_idx, unsigned long data_size,
 362                               struct lttng_ust_shm_handle *handle)
 363 {
 364         struct channel *chan = shmp(handle, buf->backend.chan);
 365         struct packet_header *header =
 366                 (struct packet_header *)
 367                         lib_ring_buffer_offset_address(&buf->backend,
 368                                 subbuf_idx * chan->backend.subbuf_size,
 369                                 handle);
 370         unsigned long records_lost = 0;
 371
 372         assert(header);
 373         if (!header)
 374                 return;
 375         header->ctx.timestamp_end = tsc;
 376         header->ctx.content_size =
 377                 (uint64_t) data_size * CHAR_BIT;                /* in bits */
 378         header->ctx.packet_size =
 379                 (uint64_t) PAGE_ALIGN(data_size) * CHAR_BIT;    /* in bits */
 380
 381         records_lost += lib_ring_buffer_get_records_lost_full(&client_config, buf);
 382         records_lost += lib_ring_buffer_get_records_lost_wrap(&client_config, buf);
 383         records_lost += lib_ring_buffer_get_records_lost_big(&client_config, buf);
 384         header->ctx.events_discarded = records_lost;
 385 }
 386
 387 static int client_buffer_create(struct lttng_ust_lib_ring_buffer *buf, void *priv,
 388                                 int cpu, const char *name, struct lttng_ust_shm_handle *handle)
 389 {
 390         return 0;
 391 }
 392
 393 static void client_buffer_finalize(struct lttng_ust_lib_ring_buffer *buf, void *priv, int cpu, struct lttng_ust_shm_handle *handle)
 394 {
 395 }
 396
 397 static void client_content_size_field(const struct lttng_ust_lib_ring_buffer_config *config,
 398                                       size_t *offset, size_t *length)
 399 {
 400         *offset = offsetof(struct packet_header, ctx.content_size);
 401         *length = sizeof(((struct packet_header *) NULL)->ctx.content_size);
 402 }
 403
 404 static void client_packet_size_field(const struct lttng_ust_lib_ring_buffer_config *config,
 405                                       size_t *offset, size_t *length)
 406 {
 407         *offset = offsetof(struct packet_header, ctx.packet_size);
 408         *length = sizeof(((struct packet_header *) NULL)->ctx.packet_size);
 409 }
 410
 411 static struct packet_header *client_packet_header(struct lttng_ust_lib_ring_buffer *buf,
 412                 struct lttng_ust_shm_handle *handle)
 413 {
 414         return lib_ring_buffer_read_offset_address(&buf->backend, 0, handle);
 415 }
 416
 417 static int client_timestamp_begin(struct lttng_ust_lib_ring_buffer *buf,
 418                 struct lttng_ust_shm_handle *handle,
 419                 uint64_t *timestamp_begin)
 420 {
 421         struct packet_header *header;
 422
 423         header = client_packet_header(buf, handle);
 424         if (!header)
 425                 return -1;
 426         *timestamp_begin = header->ctx.timestamp_begin;
 427         return 0;
 428 }
 429
 430 static int client_timestamp_end(struct lttng_ust_lib_ring_buffer *buf,
 431                 struct lttng_ust_shm_handle *handle,
 432                 uint64_t *timestamp_end)
 433 {
 434         struct packet_header *header;
 435
 436         header = client_packet_header(buf, handle);
 437         if (!header)
 438                 return -1;
 439         *timestamp_end = header->ctx.timestamp_end;
 440         return 0;
 441 }
 442
 443 static int client_events_discarded(struct lttng_ust_lib_ring_buffer *buf,
 444                 struct lttng_ust_shm_handle *handle,
 445                 uint64_t *events_discarded)
 446 {
 447         struct packet_header *header;
 448
 449         header = client_packet_header(buf, handle);
 450         if (!header)
 451                 return -1;
 452         *events_discarded = header->ctx.events_discarded;
 453         return 0;
 454 }
 455
 456 static int client_content_size(struct lttng_ust_lib_ring_buffer *buf,
 457                 struct lttng_ust_shm_handle *handle,
 458                 uint64_t *content_size)
 459 {
 460         struct packet_header *header;
 461
 462         header = client_packet_header(buf, handle);
 463         if (!header)
 464                 return -1;
 465         *content_size = header->ctx.content_size;
 466         return 0;
 467 }
 468
 469 static int client_packet_size(struct lttng_ust_lib_ring_buffer *buf,
 470                 struct lttng_ust_shm_handle *handle,
 471                 uint64_t *packet_size)
 472 {
 473         struct packet_header *header;
 474
 475         header = client_packet_header(buf, handle);
 476         if (!header)
 477                 return -1;
 478         *packet_size = header->ctx.packet_size;
 479         return 0;
 480 }
 481
 482 static int client_stream_id(struct lttng_ust_lib_ring_buffer *buf,
 483                 struct lttng_ust_shm_handle *handle,
 484                 uint64_t *stream_id)
 485 {
 486         struct packet_header *header;
 487
 488         header = client_packet_header(buf, handle);
 489         if (!header)
 490                 return -1;
 491         *stream_id = header->stream_id;
 492         return 0;
 493 }
 494
 495 static int client_current_timestamp(struct lttng_ust_lib_ring_buffer *buf,
 496                 struct lttng_ust_shm_handle *handle,
 497                 uint64_t *ts)
 498 {
 499         struct channel *chan;
 500
 501         chan = shmp(handle, handle->chan);
 502         *ts = client_ring_buffer_clock_read(chan);
 503
 504         return 0;
 505 }
 506
 507 static const
 508 struct lttng_ust_client_lib_ring_buffer_client_cb client_cb = {
 509         .parent = {
 510                 .ring_buffer_clock_read = client_ring_buffer_clock_read,
 511                 .record_header_size = client_record_header_size,
 512                 .subbuffer_header_size = client_packet_header_size,
 513                 .buffer_begin = client_buffer_begin,
 514                 .buffer_end = client_buffer_end,
 515                 .buffer_create = client_buffer_create,
 516                 .buffer_finalize = client_buffer_finalize,
 517                 .content_size_field = client_content_size_field,
 518                 .packet_size_field = client_packet_size_field,
 519         },
 520         .timestamp_begin = client_timestamp_begin,
 521         .timestamp_end = client_timestamp_end,
 522         .events_discarded = client_events_discarded,
 523         .content_size = client_content_size,
 524         .packet_size = client_packet_size,
 525         .stream_id = client_stream_id,
 526         .current_timestamp = client_current_timestamp,
 527 };
 528
 529 static const struct lttng_ust_lib_ring_buffer_config client_config = {
 530         .cb.ring_buffer_clock_read = client_ring_buffer_clock_read,
 531         .cb.record_header_size = client_record_header_size,
 532         .cb.subbuffer_header_size = client_packet_header_size,
 533         .cb.buffer_begin = client_buffer_begin,
 534         .cb.buffer_end = client_buffer_end,
 535         .cb.buffer_create = client_buffer_create,
 536         .cb.buffer_finalize = client_buffer_finalize,
 537         .cb.content_size_field = client_content_size_field,
 538         .cb.packet_size_field = client_packet_size_field,
 539
 540         .tsc_bits = LTTNG_COMPACT_TSC_BITS,
 541         .alloc = RING_BUFFER_ALLOC_PER_CPU,
 542         .sync = RING_BUFFER_SYNC_GLOBAL,
 543         .mode = RING_BUFFER_MODE_TEMPLATE,
 544         .backend = RING_BUFFER_PAGE,
 545         .output = RING_BUFFER_MMAP,
 546         .oops = RING_BUFFER_OOPS_CONSISTENCY,
 547         .ipi = RING_BUFFER_NO_IPI_BARRIER,
 548         .wakeup = LTTNG_CLIENT_WAKEUP,
 549         .client_type = LTTNG_CLIENT_TYPE,
 550
 551         .cb_ptr = &client_cb.parent,
 552 };
 553
 554 const struct lttng_ust_client_lib_ring_buffer_client_cb *LTTNG_CLIENT_CALLBACKS = &client_cb;
 555
 556 static
 557 struct lttng_channel *_channel_create(const char *name,
 558                                 void *buf_addr,
 559                                 size_t subbuf_size, size_t num_subbuf,
 560                                 unsigned int switch_timer_interval,
 561                                 unsigned int read_timer_interval,
 562                                 unsigned char *uuid,
 563                                 uint32_t chan_id,
 564                                 const int *stream_fds, int nr_stream_fds)
 565 {
 566         struct lttng_channel chan_priv_init;
 567         struct lttng_ust_shm_handle *handle;
 568         struct lttng_channel *lttng_chan;
 569         void *priv;
 570
 571         memset(&chan_priv_init, 0, sizeof(chan_priv_init));
 572         memcpy(chan_priv_init.uuid, uuid, LTTNG_UST_UUID_LEN);
 573         chan_priv_init.id = chan_id;
 574         handle = channel_create(&client_config, name,
 575                         &priv, __alignof__(struct lttng_channel),
 576                         sizeof(struct lttng_channel),
 577                         &chan_priv_init,
 578                         buf_addr, subbuf_size, num_subbuf,
 579                         switch_timer_interval, read_timer_interval,
 580                         stream_fds, nr_stream_fds);
 581         if (!handle)
 582                 return NULL;
 583         lttng_chan = priv;
 584         lttng_chan->handle = handle;
 585         lttng_chan->chan = shmp(handle, handle->chan);
 586         return lttng_chan;
 587 }
 588
 589 static
 590 void lttng_channel_destroy(struct lttng_channel *chan)
 591 {
 592         channel_destroy(chan->chan, chan->handle, 1);
 593 }
 594
 595 static
 596 int lttng_event_reserve(struct lttng_ust_lib_ring_buffer_ctx *ctx,
 597                       uint32_t event_id)
 598 {
 599         struct lttng_channel *lttng_chan = channel_get_private(ctx->chan);
 600         int ret, cpu;
 601
 602         cpu = lib_ring_buffer_get_cpu(&client_config);
 603         if (cpu < 0)
 604                 return -EPERM;
 605         ctx->cpu = cpu;
 606
 607         switch (lttng_chan->header_type) {
 608         case 1: /* compact */
 609                 if (event_id > 30)
 610                         ctx->rflags |= LTTNG_RFLAG_EXTENDED;
 611                 break;
 612         case 2: /* large */
 613                 if (event_id > 65534)
 614                         ctx->rflags |= LTTNG_RFLAG_EXTENDED;
 615                 break;
 616         default:
 617                 WARN_ON_ONCE(1);
 618         }
 619
 620         ret = lib_ring_buffer_reserve(&client_config, ctx);
 621         if (ret)
 622                 goto put;
 623         lttng_write_event_header(&client_config, ctx, event_id);
 624         return 0;
 625 put:
 626         lib_ring_buffer_put_cpu(&client_config);
 627         return ret;
 628 }
 629
 630 static
 631 void lttng_event_commit(struct lttng_ust_lib_ring_buffer_ctx *ctx)
 632 {
 633         lib_ring_buffer_commit(&client_config, ctx);
 634         lib_ring_buffer_put_cpu(&client_config);
 635 }
 636
 637 static
 638 void lttng_event_write(struct lttng_ust_lib_ring_buffer_ctx *ctx, const void *src,
 639                      size_t len)
 640 {
 641         lib_ring_buffer_write(&client_config, ctx, src, len);
 642 }
 643
 644 static
 645 void lttng_event_strcpy(struct lttng_ust_lib_ring_buffer_ctx *ctx, const char *src,
 646                      size_t len)
 647 {
 648         lib_ring_buffer_strcpy(&client_config, ctx, src, len, '#');
 649 }
 650
 651 #if 0
 652 static
 653 wait_queue_head_t *lttng_get_reader_wait_queue(struct channel *chan)
 654 {
 655         return &chan->read_wait;
 656 }
 657
 658 static
 659 wait_queue_head_t *lttng_get_hp_wait_queue(struct channel *chan)
 660 {
 661         return &chan->hp_wait;
 662 }
 663 #endif //0
 664
 665 static
 666 int lttng_is_finalized(struct channel *chan)
 667 {
 668         return lib_ring_buffer_channel_is_finalized(chan);
 669 }
 670
 671 static
 672 int lttng_is_disabled(struct channel *chan)
 673 {
 674         return lib_ring_buffer_channel_is_disabled(chan);
 675 }
 676
 677 static
 678 int lttng_flush_buffer(struct channel *chan, struct lttng_ust_shm_handle *handle)
 679 {
 680         struct lttng_ust_lib_ring_buffer *buf;
 681         int cpu;
 682
 683         for_each_channel_cpu(cpu, chan) {
 684                 int shm_fd, wait_fd, wakeup_fd;
 685                 uint64_t memory_map_size;
 686
 687                 buf = channel_get_ring_buffer(&client_config, chan,
 688                                 cpu, handle, &shm_fd, &wait_fd,
 689                                 &wakeup_fd, &memory_map_size);
 690                 lib_ring_buffer_switch(&client_config, buf,
 691                                 SWITCH_ACTIVE, handle);
 692         }
 693         return 0;
 694 }
 695
 696 static struct lttng_transport lttng_relay_transport = {
 697         .name = "relay-" RING_BUFFER_MODE_TEMPLATE_STRING "-mmap",
 698         .ops = {
 699                 .channel_create = _channel_create,
 700                 .channel_destroy = lttng_channel_destroy,
 701                 .u.has_strcpy = 1,
 702                 .event_reserve = lttng_event_reserve,
 703                 .event_commit = lttng_event_commit,
 704                 .event_write = lttng_event_write,
 705                 .packet_avail_size = NULL,      /* Would be racy anyway */
 706                 //.get_reader_wait_queue = lttng_get_reader_wait_queue,
 707                 //.get_hp_wait_queue = lttng_get_hp_wait_queue,
 708                 .is_finalized = lttng_is_finalized,
 709                 .is_disabled = lttng_is_disabled,
 710                 .flush_buffer = lttng_flush_buffer,
 711                 .event_strcpy = lttng_event_strcpy,
 712         },
 713         .client_config = &client_config,
 714 };
 715
 716 void RING_BUFFER_MODE_TEMPLATE_INIT(void)
 717 {
 718         DBG("LTT : ltt ring buffer client \"%s\" init\n",
 719                 "relay-" RING_BUFFER_MODE_TEMPLATE_STRING "-mmap");
 720         lttng_transport_register(&lttng_relay_transport);
 721 }
 722
 723 void RING_BUFFER_MODE_TEMPLATE_EXIT(void)
 724 {
 725         DBG("LTT : ltt ring buffer client \"%s\" exit\n",
 726                 "relay-" RING_BUFFER_MODE_TEMPLATE_STRING "-mmap");
 727         lttng_transport_unregister(&lttng_relay_transport);
 728 }