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         uint64_t stream_instance_id;
  49
  50         struct {
  51                 /* Stream packet context */
  52                 uint64_t timestamp_begin;       /* Cycle count at subbuffer start */
  53                 uint64_t timestamp_end;         /* Cycle count at subbuffer end */
  54                 uint64_t content_size;          /* Size of data in subbuffer */
  55                 uint64_t packet_size;           /* Subbuffer size (include padding) */
  56                 uint64_t packet_seq_num;        /* Packet sequence number */
  57                 unsigned long events_discarded; /*
  58                                                  * Events lost in this subbuffer since
  59                                                  * the beginning of the trace.
  60                                                  * (may overflow)
  61                                                  */
  62                 uint32_t cpu_id;                /* CPU id associated with stream */
  63                 uint8_t header_end;             /* End of header */
  64         } ctx;
  65 };
  66
  67
  68 static inline uint64_t lib_ring_buffer_clock_read(struct channel *chan)
  69 {
  70         return trace_clock_read64();
  71 }
  72
  73 static inline
  74 size_t ctx_get_size(size_t offset, struct lttng_ctx *ctx)
  75 {
  76         int i;
  77         size_t orig_offset = offset;
  78
  79         if (caa_likely(!ctx))
  80                 return 0;
  81         offset += lib_ring_buffer_align(offset, ctx->largest_align);
  82         for (i = 0; i < ctx->nr_fields; i++)
  83                 offset += ctx->fields[i].get_size(&ctx->fields[i], offset);
  84         return offset - orig_offset;
  85 }
  86
  87 static inline
  88 void ctx_record(struct lttng_ust_lib_ring_buffer_ctx *bufctx,
  89                 struct lttng_channel *chan,
  90                 struct lttng_ctx *ctx)
  91 {
  92         int i;
  93
  94         if (caa_likely(!ctx))
  95                 return;
  96         lib_ring_buffer_align_ctx(bufctx, ctx->largest_align);
  97         for (i = 0; i < ctx->nr_fields; i++)
  98                 ctx->fields[i].record(&ctx->fields[i], bufctx, chan);
  99 }
 100
 101 /*
 102  * record_header_size - Calculate the header size and padding necessary.
 103  * @config: ring buffer instance configuration
 104  * @chan: channel
 105  * @offset: offset in the write buffer
 106  * @pre_header_padding: padding to add before the header (output)
 107  * @ctx: reservation context
 108  *
 109  * Returns the event header size (including padding).
 110  *
 111  * The payload must itself determine its own alignment from the biggest type it
 112  * contains.
 113  */
 114 static __inline__
 115 size_t record_header_size(const struct lttng_ust_lib_ring_buffer_config *config,
 116                                  struct channel *chan, size_t offset,
 117                                  size_t *pre_header_padding,
 118                                  struct lttng_ust_lib_ring_buffer_ctx *ctx)
 119 {
 120         struct lttng_channel *lttng_chan = channel_get_private(chan);
 121         struct lttng_event *event = ctx->priv;
 122         size_t orig_offset = offset;
 123         size_t padding;
 124
 125         switch (lttng_chan->header_type) {
 126         case 1: /* compact */
 127                 padding = lib_ring_buffer_align(offset, lttng_alignof(uint32_t));
 128                 offset += padding;
 129                 if (!(ctx->rflags & (RING_BUFFER_RFLAG_FULL_TSC | LTTNG_RFLAG_EXTENDED))) {
 130                         offset += sizeof(uint32_t);     /* id and timestamp */
 131                 } else {
 132                         /* Minimum space taken by LTTNG_COMPACT_EVENT_BITS id */
 133                         offset += (LTTNG_COMPACT_EVENT_BITS + CHAR_BIT - 1) / CHAR_BIT;
 134                         /* Align extended struct on largest member */
 135                         offset += lib_ring_buffer_align(offset, lttng_alignof(uint64_t));
 136                         offset += sizeof(uint32_t);     /* id */
 137                         offset += lib_ring_buffer_align(offset, lttng_alignof(uint64_t));
 138                         offset += sizeof(uint64_t);     /* timestamp */
 139                 }
 140                 break;
 141         case 2: /* large */
 142                 padding = lib_ring_buffer_align(offset, lttng_alignof(uint16_t));
 143                 offset += padding;
 144                 offset += sizeof(uint16_t);
 145                 if (!(ctx->rflags & (RING_BUFFER_RFLAG_FULL_TSC | LTTNG_RFLAG_EXTENDED))) {
 146                         offset += lib_ring_buffer_align(offset, lttng_alignof(uint32_t));
 147                         offset += sizeof(uint32_t);     /* timestamp */
 148                 } else {
 149                         /* Align extended struct on largest member */
 150                         offset += lib_ring_buffer_align(offset, lttng_alignof(uint64_t));
 151                         offset += sizeof(uint32_t);     /* id */
 152                         offset += lib_ring_buffer_align(offset, lttng_alignof(uint64_t));
 153                         offset += sizeof(uint64_t);     /* timestamp */
 154                 }
 155                 break;
 156         default:
 157                 padding = 0;
 158                 WARN_ON_ONCE(1);
 159         }
 160         offset += ctx_get_size(offset, event->ctx);
 161         offset += ctx_get_size(offset, lttng_chan->ctx);
 162
 163         *pre_header_padding = padding;
 164         return offset - orig_offset;
 165 }
 166
 167 #include "../libringbuffer/api.h"
 168 #include "lttng-rb-clients.h"
 169
 170 static
 171 void lttng_write_event_header_slow(const struct lttng_ust_lib_ring_buffer_config *config,
 172                                  struct lttng_ust_lib_ring_buffer_ctx *ctx,
 173                                  uint32_t event_id);
 174
 175 /*
 176  * lttng_write_event_header
 177  *
 178  * Writes the event header to the offset (already aligned on 32-bits).
 179  *
 180  * @config: ring buffer instance configuration
 181  * @ctx: reservation context
 182  * @event_id: event ID
 183  */
 184 static __inline__
 185 void lttng_write_event_header(const struct lttng_ust_lib_ring_buffer_config *config,
 186                             struct lttng_ust_lib_ring_buffer_ctx *ctx,
 187                             uint32_t event_id)
 188 {
 189         struct lttng_channel *lttng_chan = channel_get_private(ctx->chan);
 190         struct lttng_stack_ctx *lttng_ctx = ctx->priv2;
 191
 192         if (caa_unlikely(ctx->rflags))
 193                 goto slow_path;
 194
 195         switch (lttng_chan->header_type) {
 196         case 1: /* compact */
 197         {
 198                 uint32_t id_time = 0;
 199
 200                 bt_bitfield_write(&id_time, uint32_t,
 201                                 0,
 202                                 LTTNG_COMPACT_EVENT_BITS,
 203                                 event_id);
 204                 bt_bitfield_write(&id_time, uint32_t,
 205                                 LTTNG_COMPACT_EVENT_BITS,
 206                                 LTTNG_COMPACT_TSC_BITS,
 207                                 ctx->tsc);
 208                 lib_ring_buffer_write(config, ctx, &id_time, sizeof(id_time));
 209                 break;
 210         }
 211         case 2: /* large */
 212         {
 213                 uint32_t timestamp = (uint32_t) ctx->tsc;
 214                 uint16_t id = event_id;
 215
 216                 lib_ring_buffer_write(config, ctx, &id, sizeof(id));
 217                 lib_ring_buffer_align_ctx(ctx, lttng_alignof(uint32_t));
 218                 lib_ring_buffer_write(config, ctx, &timestamp, sizeof(timestamp));
 219                 break;
 220         }
 221         default:
 222                 WARN_ON_ONCE(1);
 223         }
 224
 225         ctx_record(ctx, lttng_chan, lttng_ctx->chan_ctx);
 226         ctx_record(ctx, lttng_chan, lttng_ctx->event_ctx);
 227         lib_ring_buffer_align_ctx(ctx, ctx->largest_align);
 228
 229         return;
 230
 231 slow_path:
 232         lttng_write_event_header_slow(config, ctx, event_id);
 233 }
 234
 235 static
 236 void lttng_write_event_header_slow(const struct lttng_ust_lib_ring_buffer_config *config,
 237                                  struct lttng_ust_lib_ring_buffer_ctx *ctx,
 238                                  uint32_t event_id)
 239 {
 240         struct lttng_channel *lttng_chan = channel_get_private(ctx->chan);
 241         struct lttng_stack_ctx *lttng_ctx = ctx->priv2;
 242
 243         switch (lttng_chan->header_type) {
 244         case 1: /* compact */
 245                 if (!(ctx->rflags & (RING_BUFFER_RFLAG_FULL_TSC | LTTNG_RFLAG_EXTENDED))) {
 246                         uint32_t id_time = 0;
 247
 248                         bt_bitfield_write(&id_time, uint32_t,
 249                                         0,
 250                                         LTTNG_COMPACT_EVENT_BITS,
 251                                         event_id);
 252                         bt_bitfield_write(&id_time, uint32_t,
 253                                         LTTNG_COMPACT_EVENT_BITS,
 254                                         LTTNG_COMPACT_TSC_BITS,
 255                                         ctx->tsc);
 256                         lib_ring_buffer_write(config, ctx, &id_time, sizeof(id_time));
 257                 } else {
 258                         uint8_t id = 0;
 259                         uint64_t timestamp = ctx->tsc;
 260
 261                         bt_bitfield_write(&id, uint8_t,
 262                                         0,
 263                                         LTTNG_COMPACT_EVENT_BITS,
 264                                         31);
 265                         lib_ring_buffer_write(config, ctx, &id, sizeof(id));
 266                         /* Align extended struct on largest member */
 267                         lib_ring_buffer_align_ctx(ctx, lttng_alignof(uint64_t));
 268                         lib_ring_buffer_write(config, ctx, &event_id, sizeof(event_id));
 269                         lib_ring_buffer_align_ctx(ctx, lttng_alignof(uint64_t));
 270                         lib_ring_buffer_write(config, ctx, &timestamp, sizeof(timestamp));
 271                 }
 272                 break;
 273         case 2: /* large */
 274         {
 275                 if (!(ctx->rflags & (RING_BUFFER_RFLAG_FULL_TSC | LTTNG_RFLAG_EXTENDED))) {
 276                         uint32_t timestamp = (uint32_t) ctx->tsc;
 277                         uint16_t id = event_id;
 278
 279                         lib_ring_buffer_write(config, ctx, &id, sizeof(id));
 280                         lib_ring_buffer_align_ctx(ctx, lttng_alignof(uint32_t));
 281                         lib_ring_buffer_write(config, ctx, &timestamp, sizeof(timestamp));
 282                 } else {
 283                         uint16_t id = 65535;
 284                         uint64_t timestamp = ctx->tsc;
 285
 286                         lib_ring_buffer_write(config, ctx, &id, sizeof(id));
 287                         /* Align extended struct on largest member */
 288                         lib_ring_buffer_align_ctx(ctx, lttng_alignof(uint64_t));
 289                         lib_ring_buffer_write(config, ctx, &event_id, sizeof(event_id));
 290                         lib_ring_buffer_align_ctx(ctx, lttng_alignof(uint64_t));
 291                         lib_ring_buffer_write(config, ctx, &timestamp, sizeof(timestamp));
 292                 }
 293                 break;
 294         }
 295         default:
 296                 WARN_ON_ONCE(1);
 297         }
 298         ctx_record(ctx, lttng_chan, lttng_ctx->chan_ctx);
 299         ctx_record(ctx, lttng_chan, lttng_ctx->event_ctx);
 300         lib_ring_buffer_align_ctx(ctx, ctx->largest_align);
 301 }
 302
 303 static const struct lttng_ust_lib_ring_buffer_config client_config;
 304
 305 static uint64_t client_ring_buffer_clock_read(struct channel *chan)
 306 {
 307         return lib_ring_buffer_clock_read(chan);
 308 }
 309
 310 static
 311 size_t client_record_header_size(const struct lttng_ust_lib_ring_buffer_config *config,
 312                                  struct channel *chan, size_t offset,
 313                                  size_t *pre_header_padding,
 314                                  struct lttng_ust_lib_ring_buffer_ctx *ctx)
 315 {
 316         return record_header_size(config, chan, offset,
 317                                   pre_header_padding, ctx);
 318 }
 319
 320 /**
 321  * client_packet_header_size - called on buffer-switch to a new sub-buffer
 322  *
 323  * Return header size without padding after the structure. Don't use packed
 324  * structure because gcc generates inefficient code on some architectures
 325  * (powerpc, mips..)
 326  */
 327 static size_t client_packet_header_size(void)
 328 {
 329         return offsetof(struct packet_header, ctx.header_end);
 330 }
 331
 332 static void client_buffer_begin(struct lttng_ust_lib_ring_buffer *buf, uint64_t tsc,
 333                                 unsigned int subbuf_idx,
 334                                 struct lttng_ust_shm_handle *handle)
 335 {
 336         struct channel *chan = shmp(handle, buf->backend.chan);
 337         struct packet_header *header =
 338                 (struct packet_header *)
 339                         lib_ring_buffer_offset_address(&buf->backend,
 340                                 subbuf_idx * chan->backend.subbuf_size,
 341                                 handle);
 342         struct lttng_channel *lttng_chan = channel_get_private(chan);
 343         uint64_t cnt = shmp_index(handle, buf->backend.buf_cnt, subbuf_idx)->seq_cnt;
 344
 345         assert(header);
 346         if (!header)
 347                 return;
 348         header->magic = CTF_MAGIC_NUMBER;
 349         memcpy(header->uuid, lttng_chan->uuid, sizeof(lttng_chan->uuid));
 350         header->stream_id = lttng_chan->id;
 351         header->stream_instance_id = buf->backend.cpu;
 352         header->ctx.timestamp_begin = tsc;
 353         header->ctx.timestamp_end = 0;
 354         header->ctx.content_size = ~0ULL; /* for debugging */
 355         header->ctx.packet_size = ~0ULL;
 356         header->ctx.packet_seq_num = chan->backend.num_subbuf * cnt + subbuf_idx;
 357         header->ctx.events_discarded = 0;
 358         header->ctx.cpu_id = buf->backend.cpu;
 359 }
 360
 361 /*
 362  * offset is assumed to never be 0 here : never deliver a completely empty
 363  * subbuffer. data_size is between 1 and subbuf_size.
 364  */
 365 static void client_buffer_end(struct lttng_ust_lib_ring_buffer *buf, uint64_t tsc,
 366                               unsigned int subbuf_idx, unsigned long data_size,
 367                               struct lttng_ust_shm_handle *handle)
 368 {
 369         struct channel *chan = shmp(handle, buf->backend.chan);
 370         struct packet_header *header =
 371                 (struct packet_header *)
 372                         lib_ring_buffer_offset_address(&buf->backend,
 373                                 subbuf_idx * chan->backend.subbuf_size,
 374                                 handle);
 375         unsigned long records_lost = 0;
 376
 377         assert(header);
 378         if (!header)
 379                 return;
 380         header->ctx.timestamp_end = tsc;
 381         header->ctx.content_size =
 382                 (uint64_t) data_size * CHAR_BIT;                /* in bits */
 383         header->ctx.packet_size =
 384                 (uint64_t) PAGE_ALIGN(data_size) * CHAR_BIT;    /* in bits */
 385
 386         records_lost += lib_ring_buffer_get_records_lost_full(&client_config, buf);
 387         records_lost += lib_ring_buffer_get_records_lost_wrap(&client_config, buf);
 388         records_lost += lib_ring_buffer_get_records_lost_big(&client_config, buf);
 389         header->ctx.events_discarded = records_lost;
 390 }
 391
 392 static int client_buffer_create(struct lttng_ust_lib_ring_buffer *buf, void *priv,
 393                                 int cpu, const char *name, struct lttng_ust_shm_handle *handle)
 394 {
 395         return 0;
 396 }
 397
 398 static void client_buffer_finalize(struct lttng_ust_lib_ring_buffer *buf, void *priv, int cpu, struct lttng_ust_shm_handle *handle)
 399 {
 400 }
 401
 402 static void client_content_size_field(const struct lttng_ust_lib_ring_buffer_config *config,
 403                                       size_t *offset, size_t *length)
 404 {
 405         *offset = offsetof(struct packet_header, ctx.content_size);
 406         *length = sizeof(((struct packet_header *) NULL)->ctx.content_size);
 407 }
 408
 409 static void client_packet_size_field(const struct lttng_ust_lib_ring_buffer_config *config,
 410                                       size_t *offset, size_t *length)
 411 {
 412         *offset = offsetof(struct packet_header, ctx.packet_size);
 413         *length = sizeof(((struct packet_header *) NULL)->ctx.packet_size);
 414 }
 415
 416 static struct packet_header *client_packet_header(struct lttng_ust_lib_ring_buffer *buf,
 417                 struct lttng_ust_shm_handle *handle)
 418 {
 419         return lib_ring_buffer_read_offset_address(&buf->backend, 0, handle);
 420 }
 421
 422 static int client_timestamp_begin(struct lttng_ust_lib_ring_buffer *buf,
 423                 struct lttng_ust_shm_handle *handle,
 424                 uint64_t *timestamp_begin)
 425 {
 426         struct packet_header *header;
 427
 428         header = client_packet_header(buf, handle);
 429         if (!header)
 430                 return -1;
 431         *timestamp_begin = header->ctx.timestamp_begin;
 432         return 0;
 433 }
 434
 435 static int client_timestamp_end(struct lttng_ust_lib_ring_buffer *buf,
 436                 struct lttng_ust_shm_handle *handle,
 437                 uint64_t *timestamp_end)
 438 {
 439         struct packet_header *header;
 440
 441         header = client_packet_header(buf, handle);
 442         if (!header)
 443                 return -1;
 444         *timestamp_end = header->ctx.timestamp_end;
 445         return 0;
 446 }
 447
 448 static int client_events_discarded(struct lttng_ust_lib_ring_buffer *buf,
 449                 struct lttng_ust_shm_handle *handle,
 450                 uint64_t *events_discarded)
 451 {
 452         struct packet_header *header;
 453
 454         header = client_packet_header(buf, handle);
 455         if (!header)
 456                 return -1;
 457         *events_discarded = header->ctx.events_discarded;
 458         return 0;
 459 }
 460
 461 static int client_content_size(struct lttng_ust_lib_ring_buffer *buf,
 462                 struct lttng_ust_shm_handle *handle,
 463                 uint64_t *content_size)
 464 {
 465         struct packet_header *header;
 466
 467         header = client_packet_header(buf, handle);
 468         if (!header)
 469                 return -1;
 470         *content_size = header->ctx.content_size;
 471         return 0;
 472 }
 473
 474 static int client_packet_size(struct lttng_ust_lib_ring_buffer *buf,
 475                 struct lttng_ust_shm_handle *handle,
 476                 uint64_t *packet_size)
 477 {
 478         struct packet_header *header;
 479
 480         header = client_packet_header(buf, handle);
 481         if (!header)
 482                 return -1;
 483         *packet_size = header->ctx.packet_size;
 484         return 0;
 485 }
 486
 487 static int client_stream_id(struct lttng_ust_lib_ring_buffer *buf,
 488                 struct lttng_ust_shm_handle *handle,
 489                 uint64_t *stream_id)
 490 {
 491         struct packet_header *header;
 492
 493         header = client_packet_header(buf, handle);
 494         if (!header)
 495                 return -1;
 496         *stream_id = header->stream_id;
 497         return 0;
 498 }
 499
 500 static int client_current_timestamp(struct lttng_ust_lib_ring_buffer *buf,
 501                 struct lttng_ust_shm_handle *handle,
 502                 uint64_t *ts)
 503 {
 504         struct channel *chan;
 505
 506         chan = shmp(handle, handle->chan);
 507         *ts = client_ring_buffer_clock_read(chan);
 508
 509         return 0;
 510 }
 511
 512 static int client_sequence_number(struct lttng_ust_lib_ring_buffer *buf,
 513                 struct lttng_ust_shm_handle *handle,
 514                 uint64_t *seq)
 515 {
 516         struct packet_header *header;
 517
 518         header = client_packet_header(buf, handle);
 519         *seq = header->ctx.packet_seq_num;
 520         return 0;
 521 }
 522
 523 static const
 524 struct lttng_ust_client_lib_ring_buffer_client_cb client_cb = {
 525         .parent = {
 526                 .ring_buffer_clock_read = client_ring_buffer_clock_read,
 527                 .record_header_size = client_record_header_size,
 528                 .subbuffer_header_size = client_packet_header_size,
 529                 .buffer_begin = client_buffer_begin,
 530                 .buffer_end = client_buffer_end,
 531                 .buffer_create = client_buffer_create,
 532                 .buffer_finalize = client_buffer_finalize,
 533                 .content_size_field = client_content_size_field,
 534                 .packet_size_field = client_packet_size_field,
 535         },
 536         .timestamp_begin = client_timestamp_begin,
 537         .timestamp_end = client_timestamp_end,
 538         .events_discarded = client_events_discarded,
 539         .content_size = client_content_size,
 540         .packet_size = client_packet_size,
 541         .stream_id = client_stream_id,
 542         .current_timestamp = client_current_timestamp,
 543         .sequence_number = client_sequence_number,
 544 };
 545
 546 static const struct lttng_ust_lib_ring_buffer_config client_config = {
 547         .cb.ring_buffer_clock_read = client_ring_buffer_clock_read,
 548         .cb.record_header_size = client_record_header_size,
 549         .cb.subbuffer_header_size = client_packet_header_size,
 550         .cb.buffer_begin = client_buffer_begin,
 551         .cb.buffer_end = client_buffer_end,
 552         .cb.buffer_create = client_buffer_create,
 553         .cb.buffer_finalize = client_buffer_finalize,
 554         .cb.content_size_field = client_content_size_field,
 555         .cb.packet_size_field = client_packet_size_field,
 556
 557         .tsc_bits = LTTNG_COMPACT_TSC_BITS,
 558         .alloc = RING_BUFFER_ALLOC_PER_CPU,
 559         .sync = RING_BUFFER_SYNC_GLOBAL,
 560         .mode = RING_BUFFER_MODE_TEMPLATE,
 561         .backend = RING_BUFFER_PAGE,
 562         .output = RING_BUFFER_MMAP,
 563         .oops = RING_BUFFER_OOPS_CONSISTENCY,
 564         .ipi = RING_BUFFER_NO_IPI_BARRIER,
 565         .wakeup = LTTNG_CLIENT_WAKEUP,
 566         .client_type = LTTNG_CLIENT_TYPE,
 567
 568         .cb_ptr = &client_cb.parent,
 569 };
 570
 571 const struct lttng_ust_client_lib_ring_buffer_client_cb *LTTNG_CLIENT_CALLBACKS = &client_cb;
 572
 573 static
 574 struct lttng_channel *_channel_create(const char *name,
 575                                 void *buf_addr,
 576                                 size_t subbuf_size, size_t num_subbuf,
 577                                 unsigned int switch_timer_interval,
 578                                 unsigned int read_timer_interval,
 579                                 unsigned char *uuid,
 580                                 uint32_t chan_id,
 581                                 const int *stream_fds, int nr_stream_fds)
 582 {
 583         struct lttng_channel chan_priv_init;
 584         struct lttng_ust_shm_handle *handle;
 585         struct lttng_channel *lttng_chan;
 586         void *priv;
 587
 588         memset(&chan_priv_init, 0, sizeof(chan_priv_init));
 589         memcpy(chan_priv_init.uuid, uuid, LTTNG_UST_UUID_LEN);
 590         chan_priv_init.id = chan_id;
 591         handle = channel_create(&client_config, name,
 592                         &priv, __alignof__(struct lttng_channel),
 593                         sizeof(struct lttng_channel),
 594                         &chan_priv_init,
 595                         buf_addr, subbuf_size, num_subbuf,
 596                         switch_timer_interval, read_timer_interval,
 597                         stream_fds, nr_stream_fds);
 598         if (!handle)
 599                 return NULL;
 600         lttng_chan = priv;
 601         lttng_chan->handle = handle;
 602         lttng_chan->chan = shmp(handle, handle->chan);
 603         return lttng_chan;
 604 }
 605
 606 static
 607 void lttng_channel_destroy(struct lttng_channel *chan)
 608 {
 609         channel_destroy(chan->chan, chan->handle, 1);
 610 }
 611
 612 static
 613 int lttng_event_reserve(struct lttng_ust_lib_ring_buffer_ctx *ctx,
 614                       uint32_t event_id)
 615 {
 616         struct lttng_channel *lttng_chan = channel_get_private(ctx->chan);
 617         int ret, cpu;
 618
 619         cpu = lib_ring_buffer_get_cpu(&client_config);
 620         if (cpu < 0)
 621                 return -EPERM;
 622         ctx->cpu = cpu;
 623
 624         switch (lttng_chan->header_type) {
 625         case 1: /* compact */
 626                 if (event_id > 30)
 627                         ctx->rflags |= LTTNG_RFLAG_EXTENDED;
 628                 break;
 629         case 2: /* large */
 630                 if (event_id > 65534)
 631                         ctx->rflags |= LTTNG_RFLAG_EXTENDED;
 632                 break;
 633         default:
 634                 WARN_ON_ONCE(1);
 635         }
 636
 637         ret = lib_ring_buffer_reserve(&client_config, ctx);
 638         if (ret)
 639                 goto put;
 640         lttng_write_event_header(&client_config, ctx, event_id);
 641         return 0;
 642 put:
 643         lib_ring_buffer_put_cpu(&client_config);
 644         return ret;
 645 }
 646
 647 static
 648 void lttng_event_commit(struct lttng_ust_lib_ring_buffer_ctx *ctx)
 649 {
 650         lib_ring_buffer_commit(&client_config, ctx);
 651         lib_ring_buffer_put_cpu(&client_config);
 652 }
 653
 654 static
 655 void lttng_event_write(struct lttng_ust_lib_ring_buffer_ctx *ctx, const void *src,
 656                      size_t len)
 657 {
 658         lib_ring_buffer_write(&client_config, ctx, src, len);
 659 }
 660
 661 static
 662 void lttng_event_strcpy(struct lttng_ust_lib_ring_buffer_ctx *ctx, const char *src,
 663                      size_t len)
 664 {
 665         lib_ring_buffer_strcpy(&client_config, ctx, src, len, '#');
 666 }
 667
 668 #if 0
 669 static
 670 wait_queue_head_t *lttng_get_reader_wait_queue(struct channel *chan)
 671 {
 672         return &chan->read_wait;
 673 }
 674
 675 static
 676 wait_queue_head_t *lttng_get_hp_wait_queue(struct channel *chan)
 677 {
 678         return &chan->hp_wait;
 679 }
 680 #endif //0
 681
 682 static
 683 int lttng_is_finalized(struct channel *chan)
 684 {
 685         return lib_ring_buffer_channel_is_finalized(chan);
 686 }
 687
 688 static
 689 int lttng_is_disabled(struct channel *chan)
 690 {
 691         return lib_ring_buffer_channel_is_disabled(chan);
 692 }
 693
 694 static
 695 int lttng_flush_buffer(struct channel *chan, struct lttng_ust_shm_handle *handle)
 696 {
 697         struct lttng_ust_lib_ring_buffer *buf;
 698         int cpu;
 699
 700         for_each_channel_cpu(cpu, chan) {
 701                 int shm_fd, wait_fd, wakeup_fd;
 702                 uint64_t memory_map_size;
 703
 704                 buf = channel_get_ring_buffer(&client_config, chan,
 705                                 cpu, handle, &shm_fd, &wait_fd,
 706                                 &wakeup_fd, &memory_map_size);
 707                 lib_ring_buffer_switch(&client_config, buf,
 708                                 SWITCH_ACTIVE, handle);
 709         }
 710         return 0;
 711 }
 712
 713 static struct lttng_transport lttng_relay_transport = {
 714         .name = "relay-" RING_BUFFER_MODE_TEMPLATE_STRING "-mmap",
 715         .ops = {
 716                 .channel_create = _channel_create,
 717                 .channel_destroy = lttng_channel_destroy,
 718                 .u.has_strcpy = 1,
 719                 .event_reserve = lttng_event_reserve,
 720                 .event_commit = lttng_event_commit,
 721                 .event_write = lttng_event_write,
 722                 .packet_avail_size = NULL,      /* Would be racy anyway */
 723                 //.get_reader_wait_queue = lttng_get_reader_wait_queue,
 724                 //.get_hp_wait_queue = lttng_get_hp_wait_queue,
 725                 .is_finalized = lttng_is_finalized,
 726                 .is_disabled = lttng_is_disabled,
 727                 .flush_buffer = lttng_flush_buffer,
 728                 .event_strcpy = lttng_event_strcpy,
 729         },
 730         .client_config = &client_config,
 731 };
 732
 733 void RING_BUFFER_MODE_TEMPLATE_INIT(void)
 734 {
 735         DBG("LTT : ltt ring buffer client \"%s\" init\n",
 736                 "relay-" RING_BUFFER_MODE_TEMPLATE_STRING "-mmap");
 737         lttng_transport_register(&lttng_relay_transport);
 738 }
 739
 740 void RING_BUFFER_MODE_TEMPLATE_EXIT(void)
 741 {
 742         DBG("LTT : ltt ring buffer client \"%s\" exit\n",
 743                 "relay-" RING_BUFFER_MODE_TEMPLATE_STRING "-mmap");
 744         lttng_transport_unregister(&lttng_relay_transport);
 745 }