src/lttng-ring-buffer-client.h

   1 /* SPDX-License-Identifier: (GPL-2.0-only or LGPL-2.1-only)
   2  *
   3  * lttng-ring-buffer-client.h
   4  *
   5  * LTTng lib ring buffer client template.
   6  *
   7  * Copyright (C) 2010-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   8  */
   9
  10 #include <linux/module.h>
  11 #include <linux/types.h>
  12 #include <lttng/bitfield.h>
  13 #include <wrapper/vmalloc.h>    /* for wrapper_vmalloc_sync_mappings() */
  14 #include <wrapper/trace-clock.h>
  15 #include <lttng/events.h>
  16 #include <lttng/tracer.h>
  17 #include <ringbuffer/frontend_types.h>
  18
  19 #define LTTNG_COMPACT_EVENT_BITS        5
  20 #define LTTNG_COMPACT_TSC_BITS          27
  21
  22 static struct lttng_transport lttng_relay_transport;
  23
  24 /*
  25  * Keep the natural field alignment for _each field_ within this structure if
  26  * you ever add/remove a field from this header. Packed attribute is not used
  27  * because gcc generates poor code on at least powerpc and mips. Don't ever
  28  * let gcc add padding between the structure elements.
  29  *
  30  * The guarantee we have with timestamps is that all the events in a
  31  * packet are included (inclusive) within the begin/end timestamps of
  32  * the packet. Another guarantee we have is that the "timestamp begin",
  33  * as well as the event timestamps, are monotonically increasing (never
  34  * decrease) when moving forward in a stream (physically). But this
  35  * guarantee does not apply to "timestamp end", because it is sampled at
  36  * commit time, which is not ordered with respect to space reservation.
  37  */
  38
  39 struct packet_header {
  40         /* Trace packet header */
  41         uint32_t magic;                 /*
  42                                          * Trace magic number.
  43                                          * contains endianness information.
  44                                          */
  45         uint8_t uuid[16];
  46         uint32_t stream_id;
  47         uint64_t stream_instance_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                 uint64_t packet_seq_num;        /* Packet sequence number */
  56                 unsigned long events_discarded; /*
  57                                                  * Events lost in this subbuffer since
  58                                                  * the beginning of the trace.
  59                                                  * (may overflow)
  60                                                  */
  61                 uint32_t cpu_id;                /* CPU id associated with stream */
  62                 uint8_t header_end;             /* End of header */
  63         } ctx;
  64 };
  65
  66 struct lttng_client_ctx {
  67         size_t packet_context_len;
  68         size_t event_context_len;
  69 };
  70
  71 static inline notrace u64 lib_ring_buffer_clock_read(struct channel *chan)
  72 {
  73         return trace_clock_read64();
  74 }
  75
  76 static inline
  77 size_t ctx_get_aligned_size(size_t offset, struct lttng_kernel_ctx *ctx,
  78                 size_t ctx_len)
  79 {
  80         size_t orig_offset = offset;
  81
  82         if (likely(!ctx))
  83                 return 0;
  84         offset += lib_ring_buffer_align(offset, ctx->largest_align);
  85         offset += ctx_len;
  86         return offset - orig_offset;
  87 }
  88
  89 static inline
  90 void ctx_get_struct_size(struct lttng_kernel_ctx *ctx, size_t *ctx_len,
  91                 struct lttng_channel *chan, struct lib_ring_buffer_ctx *bufctx)
  92 {
  93         int i;
  94         size_t offset = 0;
  95
  96         if (likely(!ctx)) {
  97                 *ctx_len = 0;
  98                 return;
  99         }
 100         for (i = 0; i < ctx->nr_fields; i++) {
 101                 if (ctx->fields[i].get_size)
 102                         offset += ctx->fields[i].get_size(offset);
 103                 if (ctx->fields[i].get_size_arg)
 104                         offset += ctx->fields[i].get_size_arg(offset,
 105                                         &ctx->fields[i], bufctx, chan);
 106         }
 107         *ctx_len = offset;
 108 }
 109
 110 static inline
 111 void ctx_record(struct lib_ring_buffer_ctx *bufctx,
 112                 struct lttng_channel *chan,
 113                 struct lttng_kernel_ctx *ctx)
 114 {
 115         int i;
 116
 117         if (likely(!ctx))
 118                 return;
 119         lib_ring_buffer_align_ctx(bufctx, ctx->largest_align);
 120         for (i = 0; i < ctx->nr_fields; i++)
 121                 ctx->fields[i].record(&ctx->fields[i], bufctx, chan);
 122 }
 123
 124 /*
 125  * record_header_size - Calculate the header size and padding necessary.
 126  * @config: ring buffer instance configuration
 127  * @chan: channel
 128  * @offset: offset in the write buffer
 129  * @pre_header_padding: padding to add before the header (output)
 130  * @ctx: reservation context
 131  *
 132  * Returns the event header size (including padding).
 133  *
 134  * The payload must itself determine its own alignment from the biggest type it
 135  * contains.
 136  */
 137 static __inline__
 138 size_t record_header_size(const struct lib_ring_buffer_config *config,
 139                                  struct channel *chan, size_t offset,
 140                                  size_t *pre_header_padding,
 141                                  struct lib_ring_buffer_ctx *ctx,
 142                                  struct lttng_client_ctx *client_ctx)
 143 {
 144         struct lttng_channel *lttng_chan = channel_get_private(chan);
 145         size_t orig_offset = offset;
 146         size_t padding;
 147
 148         switch (lttng_chan->header_type) {
 149         case 1: /* compact */
 150                 padding = lib_ring_buffer_align(offset, lttng_alignof(uint32_t));
 151                 offset += padding;
 152                 if (!(ctx->priv.rflags & (RING_BUFFER_RFLAG_FULL_TSC | LTTNG_RFLAG_EXTENDED))) {
 153                         offset += sizeof(uint32_t);     /* id and timestamp */
 154                 } else {
 155                         /* Minimum space taken by LTTNG_COMPACT_EVENT_BITS id */
 156                         offset += (LTTNG_COMPACT_EVENT_BITS + CHAR_BIT - 1) / CHAR_BIT;
 157                         /* Align extended struct on largest member */
 158                         offset += lib_ring_buffer_align(offset, lttng_alignof(uint64_t));
 159                         offset += sizeof(uint32_t);     /* id */
 160                         offset += lib_ring_buffer_align(offset, lttng_alignof(uint64_t));
 161                         offset += sizeof(uint64_t);     /* timestamp */
 162                 }
 163                 break;
 164         case 2: /* large */
 165                 padding = lib_ring_buffer_align(offset, lttng_alignof(uint16_t));
 166                 offset += padding;
 167                 offset += sizeof(uint16_t);
 168                 if (!(ctx->priv.rflags & (RING_BUFFER_RFLAG_FULL_TSC | LTTNG_RFLAG_EXTENDED))) {
 169                         offset += lib_ring_buffer_align(offset, lttng_alignof(uint32_t));
 170                         offset += sizeof(uint32_t);     /* timestamp */
 171                 } else {
 172                         /* Align extended struct on largest member */
 173                         offset += lib_ring_buffer_align(offset, lttng_alignof(uint64_t));
 174                         offset += sizeof(uint32_t);     /* id */
 175                         offset += lib_ring_buffer_align(offset, lttng_alignof(uint64_t));
 176                         offset += sizeof(uint64_t);     /* timestamp */
 177                 }
 178                 break;
 179         default:
 180                 padding = 0;
 181                 WARN_ON_ONCE(1);
 182         }
 183         offset += ctx_get_aligned_size(offset, lttng_chan->ctx,
 184                         client_ctx->packet_context_len);
 185         *pre_header_padding = padding;
 186         return offset - orig_offset;
 187 }
 188
 189 #include <ringbuffer/api.h>
 190
 191 static
 192 void lttng_write_event_header_slow(const struct lib_ring_buffer_config *config,
 193                                  struct lib_ring_buffer_ctx *ctx,
 194                                  uint32_t event_id);
 195
 196 /*
 197  * lttng_write_event_header
 198  *
 199  * Writes the event header to the offset (already aligned on 32-bits).
 200  *
 201  * @config: ring buffer instance configuration
 202  * @ctx: reservation context
 203  * @event_id: event ID
 204  */
 205 static __inline__
 206 void lttng_write_event_header(const struct lib_ring_buffer_config *config,
 207                             struct lib_ring_buffer_ctx *ctx,
 208                             uint32_t event_id)
 209 {
 210         struct lttng_channel *lttng_chan = channel_get_private(ctx->priv.chan);
 211
 212         if (unlikely(ctx->priv.rflags))
 213                 goto slow_path;
 214
 215         switch (lttng_chan->header_type) {
 216         case 1: /* compact */
 217         {
 218                 uint32_t id_time = 0;
 219
 220                 bt_bitfield_write(&id_time, uint32_t,
 221                                 0,
 222                                 LTTNG_COMPACT_EVENT_BITS,
 223                                 event_id);
 224                 bt_bitfield_write(&id_time, uint32_t,
 225                                 LTTNG_COMPACT_EVENT_BITS,
 226                                 LTTNG_COMPACT_TSC_BITS,
 227                                 ctx->priv.tsc);
 228                 lib_ring_buffer_write(config, ctx, &id_time, sizeof(id_time));
 229                 break;
 230         }
 231         case 2: /* large */
 232         {
 233                 uint32_t timestamp = (uint32_t) ctx->priv.tsc;
 234                 uint16_t id = event_id;
 235
 236                 lib_ring_buffer_write(config, ctx, &id, sizeof(id));
 237                 lib_ring_buffer_align_ctx(ctx, lttng_alignof(uint32_t));
 238                 lib_ring_buffer_write(config, ctx, &timestamp, sizeof(timestamp));
 239                 break;
 240         }
 241         default:
 242                 WARN_ON_ONCE(1);
 243         }
 244
 245         ctx_record(ctx, lttng_chan, lttng_chan->ctx);
 246         lib_ring_buffer_align_ctx(ctx, ctx->largest_align);
 247
 248         return;
 249
 250 slow_path:
 251         lttng_write_event_header_slow(config, ctx, event_id);
 252 }
 253
 254 static
 255 void lttng_write_event_header_slow(const struct lib_ring_buffer_config *config,
 256                                  struct lib_ring_buffer_ctx *ctx,
 257                                  uint32_t event_id)
 258 {
 259         struct lttng_channel *lttng_chan = channel_get_private(ctx->priv.chan);
 260
 261         switch (lttng_chan->header_type) {
 262         case 1: /* compact */
 263                 if (!(ctx->priv.rflags & (RING_BUFFER_RFLAG_FULL_TSC | LTTNG_RFLAG_EXTENDED))) {
 264                         uint32_t id_time = 0;
 265
 266                         bt_bitfield_write(&id_time, uint32_t,
 267                                         0,
 268                                         LTTNG_COMPACT_EVENT_BITS,
 269                                         event_id);
 270                         bt_bitfield_write(&id_time, uint32_t,
 271                                         LTTNG_COMPACT_EVENT_BITS,
 272                                         LTTNG_COMPACT_TSC_BITS, ctx->priv.tsc);
 273                         lib_ring_buffer_write(config, ctx, &id_time, sizeof(id_time));
 274                 } else {
 275                         uint8_t id = 0;
 276                         uint64_t timestamp = ctx->priv.tsc;
 277
 278                         bt_bitfield_write(&id, uint8_t,
 279                                         0,
 280                                         LTTNG_COMPACT_EVENT_BITS,
 281                                         31);
 282                         lib_ring_buffer_write(config, ctx, &id, sizeof(id));
 283                         /* Align extended struct on largest member */
 284                         lib_ring_buffer_align_ctx(ctx, lttng_alignof(uint64_t));
 285                         lib_ring_buffer_write(config, ctx, &event_id, sizeof(event_id));
 286                         lib_ring_buffer_align_ctx(ctx, lttng_alignof(uint64_t));
 287                         lib_ring_buffer_write(config, ctx, &timestamp, sizeof(timestamp));
 288                 }
 289                 break;
 290         case 2: /* large */
 291         {
 292                 if (!(ctx->priv.rflags & (RING_BUFFER_RFLAG_FULL_TSC | LTTNG_RFLAG_EXTENDED))) {
 293                         uint32_t timestamp = (uint32_t) ctx->priv.tsc;
 294                         uint16_t id = event_id;
 295
 296                         lib_ring_buffer_write(config, ctx, &id, sizeof(id));
 297                         lib_ring_buffer_align_ctx(ctx, lttng_alignof(uint32_t));
 298                         lib_ring_buffer_write(config, ctx, &timestamp, sizeof(timestamp));
 299                 } else {
 300                         uint16_t id = 65535;
 301                         uint64_t timestamp = ctx->priv.tsc;
 302
 303                         lib_ring_buffer_write(config, ctx, &id, sizeof(id));
 304                         /* Align extended struct on largest member */
 305                         lib_ring_buffer_align_ctx(ctx, lttng_alignof(uint64_t));
 306                         lib_ring_buffer_write(config, ctx, &event_id, sizeof(event_id));
 307                         lib_ring_buffer_align_ctx(ctx, lttng_alignof(uint64_t));
 308                         lib_ring_buffer_write(config, ctx, &timestamp, sizeof(timestamp));
 309                 }
 310                 break;
 311         }
 312         default:
 313                 WARN_ON_ONCE(1);
 314         }
 315         ctx_record(ctx, lttng_chan, lttng_chan->ctx);
 316         lib_ring_buffer_align_ctx(ctx, ctx->largest_align);
 317 }
 318
 319 static const struct lib_ring_buffer_config client_config;
 320
 321 static u64 client_ring_buffer_clock_read(struct channel *chan)
 322 {
 323         return lib_ring_buffer_clock_read(chan);
 324 }
 325
 326 static
 327 size_t client_record_header_size(const struct lib_ring_buffer_config *config,
 328                                  struct channel *chan, size_t offset,
 329                                  size_t *pre_header_padding,
 330                                  struct lib_ring_buffer_ctx *ctx,
 331                                  void *client_ctx)
 332 {
 333         return record_header_size(config, chan, offset,
 334                                   pre_header_padding, ctx, client_ctx);
 335 }
 336
 337 /**
 338  * client_packet_header_size - called on buffer-switch to a new sub-buffer
 339  *
 340  * Return header size without padding after the structure. Don't use packed
 341  * structure because gcc generates inefficient code on some architectures
 342  * (powerpc, mips..)
 343  */
 344 static size_t client_packet_header_size(void)
 345 {
 346         return offsetof(struct packet_header, ctx.header_end);
 347 }
 348
 349 static void client_buffer_begin(struct lib_ring_buffer *buf, u64 tsc,
 350                                 unsigned int subbuf_idx)
 351 {
 352         struct channel *chan = buf->backend.chan;
 353         struct packet_header *header =
 354                 (struct packet_header *)
 355                         lib_ring_buffer_offset_address(&buf->backend,
 356                                 subbuf_idx * chan->backend.subbuf_size);
 357         struct lttng_channel *lttng_chan = channel_get_private(chan);
 358         struct lttng_session *session = lttng_chan->session;
 359
 360         header->magic = CTF_MAGIC_NUMBER;
 361         memcpy(header->uuid, session->uuid.b, sizeof(session->uuid));
 362         header->stream_id = lttng_chan->id;
 363         header->stream_instance_id = buf->backend.cpu;
 364         header->ctx.timestamp_begin = tsc;
 365         header->ctx.timestamp_end = 0;
 366         header->ctx.content_size = ~0ULL; /* for debugging */
 367         header->ctx.packet_size = ~0ULL;
 368         header->ctx.packet_seq_num = chan->backend.num_subbuf * \
 369                                      buf->backend.buf_cnt[subbuf_idx].seq_cnt + \
 370                                      subbuf_idx;
 371         header->ctx.events_discarded = 0;
 372         header->ctx.cpu_id = buf->backend.cpu;
 373 }
 374
 375 /*
 376  * offset is assumed to never be 0 here : never deliver a completely empty
 377  * subbuffer. data_size is between 1 and subbuf_size.
 378  */
 379 static void client_buffer_end(struct lib_ring_buffer *buf, u64 tsc,
 380                               unsigned int subbuf_idx, unsigned long data_size)
 381 {
 382         struct channel *chan = buf->backend.chan;
 383         struct packet_header *header =
 384                 (struct packet_header *)
 385                         lib_ring_buffer_offset_address(&buf->backend,
 386                                 subbuf_idx * chan->backend.subbuf_size);
 387         unsigned long records_lost = 0;
 388
 389         header->ctx.timestamp_end = tsc;
 390         header->ctx.content_size =
 391                 (uint64_t) data_size * CHAR_BIT;                /* in bits */
 392         header->ctx.packet_size =
 393                 (uint64_t) PAGE_ALIGN(data_size) * CHAR_BIT;    /* in bits */
 394         records_lost += lib_ring_buffer_get_records_lost_full(&client_config, buf);
 395         records_lost += lib_ring_buffer_get_records_lost_wrap(&client_config, buf);
 396         records_lost += lib_ring_buffer_get_records_lost_big(&client_config, buf);
 397         header->ctx.events_discarded = records_lost;
 398 }
 399
 400 static int client_buffer_create(struct lib_ring_buffer *buf, void *priv,
 401                                 int cpu, const char *name)
 402 {
 403         return 0;
 404 }
 405
 406 static void client_buffer_finalize(struct lib_ring_buffer *buf, void *priv, int cpu)
 407 {
 408 }
 409
 410 static struct packet_header *client_packet_header(
 411                 const struct lib_ring_buffer_config *config,
 412                 struct lib_ring_buffer *buf)
 413 {
 414         return lib_ring_buffer_read_offset_address(&buf->backend, 0);
 415 }
 416
 417 static int client_timestamp_begin(const struct lib_ring_buffer_config *config,
 418                 struct lib_ring_buffer *buf,
 419                 uint64_t *timestamp_begin)
 420 {
 421         struct packet_header *header = client_packet_header(config, buf);
 422         *timestamp_begin = header->ctx.timestamp_begin;
 423
 424         return 0;
 425 }
 426
 427 static int client_timestamp_end(const struct lib_ring_buffer_config *config,
 428                         struct lib_ring_buffer *buf,
 429                         uint64_t *timestamp_end)
 430 {
 431         struct packet_header *header = client_packet_header(config, buf);
 432         *timestamp_end = header->ctx.timestamp_end;
 433
 434         return 0;
 435 }
 436
 437 static int client_events_discarded(const struct lib_ring_buffer_config *config,
 438                         struct lib_ring_buffer *buf,
 439                         uint64_t *events_discarded)
 440 {
 441         struct packet_header *header = client_packet_header(config, buf);
 442         *events_discarded = header->ctx.events_discarded;
 443
 444         return 0;
 445 }
 446
 447 static int client_content_size(const struct lib_ring_buffer_config *config,
 448                         struct lib_ring_buffer *buf,
 449                         uint64_t *content_size)
 450 {
 451         struct packet_header *header = client_packet_header(config, buf);
 452         *content_size = header->ctx.content_size;
 453
 454         return 0;
 455 }
 456
 457 static int client_packet_size(const struct lib_ring_buffer_config *config,
 458                         struct lib_ring_buffer *buf,
 459                         uint64_t *packet_size)
 460 {
 461         struct packet_header *header = client_packet_header(config, buf);
 462         *packet_size = header->ctx.packet_size;
 463
 464         return 0;
 465 }
 466
 467 static int client_stream_id(const struct lib_ring_buffer_config *config,
 468                         struct lib_ring_buffer *buf,
 469                         uint64_t *stream_id)
 470 {
 471         struct channel *chan = buf->backend.chan;
 472         struct lttng_channel *lttng_chan = channel_get_private(chan);
 473
 474         *stream_id = lttng_chan->id;
 475         return 0;
 476 }
 477
 478 static int client_current_timestamp(const struct lib_ring_buffer_config *config,
 479                 struct lib_ring_buffer *bufb,
 480                 uint64_t *ts)
 481 {
 482         *ts = config->cb.ring_buffer_clock_read(bufb->backend.chan);
 483
 484         return 0;
 485 }
 486
 487 static int client_sequence_number(const struct lib_ring_buffer_config *config,
 488                         struct lib_ring_buffer *buf,
 489                         uint64_t *seq)
 490 {
 491         struct packet_header *header = client_packet_header(config, buf);
 492
 493         *seq = header->ctx.packet_seq_num;
 494
 495         return 0;
 496 }
 497
 498 static
 499 int client_instance_id(const struct lib_ring_buffer_config *config,
 500                 struct lib_ring_buffer *buf,
 501                 uint64_t *id)
 502 {
 503         *id = buf->backend.cpu;
 504
 505         return 0;
 506 }
 507
 508 static const struct lib_ring_buffer_config client_config = {
 509         .cb.ring_buffer_clock_read = client_ring_buffer_clock_read,
 510         .cb.record_header_size = client_record_header_size,
 511         .cb.subbuffer_header_size = client_packet_header_size,
 512         .cb.buffer_begin = client_buffer_begin,
 513         .cb.buffer_end = client_buffer_end,
 514         .cb.buffer_create = client_buffer_create,
 515         .cb.buffer_finalize = client_buffer_finalize,
 516
 517         .tsc_bits = LTTNG_COMPACT_TSC_BITS,
 518         .alloc = RING_BUFFER_ALLOC_PER_CPU,
 519         .sync = RING_BUFFER_SYNC_PER_CPU,
 520         .mode = RING_BUFFER_MODE_TEMPLATE,
 521         .backend = RING_BUFFER_PAGE,
 522         .output = RING_BUFFER_OUTPUT_TEMPLATE,
 523         .oops = RING_BUFFER_OOPS_CONSISTENCY,
 524         .ipi = RING_BUFFER_IPI_BARRIER,
 525         .wakeup = RING_BUFFER_WAKEUP_BY_TIMER,
 526 };
 527
 528 static
 529 void release_priv_ops(void *priv_ops)
 530 {
 531         module_put(THIS_MODULE);
 532 }
 533
 534 static
 535 void lttng_channel_destroy(struct channel *chan)
 536 {
 537         channel_destroy(chan);
 538 }
 539
 540 static
 541 struct channel *_channel_create(const char *name,
 542                                 void *priv, void *buf_addr,
 543                                 size_t subbuf_size, size_t num_subbuf,
 544                                 unsigned int switch_timer_interval,
 545                                 unsigned int read_timer_interval)
 546 {
 547         struct lttng_channel *lttng_chan = priv;
 548         struct channel *chan;
 549
 550         chan = channel_create(&client_config, name, lttng_chan, buf_addr,
 551                               subbuf_size, num_subbuf, switch_timer_interval,
 552                               read_timer_interval);
 553         if (chan) {
 554                 /*
 555                  * Ensure this module is not unloaded before we finish
 556                  * using lttng_relay_transport.ops.
 557                  */
 558                 if (!try_module_get(THIS_MODULE)) {
 559                         printk(KERN_WARNING "LTTng: Can't lock transport module.\n");
 560                         goto error;
 561                 }
 562                 chan->backend.priv_ops = &lttng_relay_transport.ops;
 563                 chan->backend.release_priv_ops = release_priv_ops;
 564         }
 565         return chan;
 566
 567 error:
 568         lttng_channel_destroy(chan);
 569         return NULL;
 570 }
 571
 572 static
 573 struct lib_ring_buffer *lttng_buffer_read_open(struct channel *chan)
 574 {
 575         struct lib_ring_buffer *buf;
 576         int cpu;
 577
 578         for_each_channel_cpu(cpu, chan) {
 579                 buf = channel_get_ring_buffer(&client_config, chan, cpu);
 580                 if (!lib_ring_buffer_open_read(buf))
 581                         return buf;
 582         }
 583         return NULL;
 584 }
 585
 586 static
 587 int lttng_buffer_has_read_closed_stream(struct channel *chan)
 588 {
 589         struct lib_ring_buffer *buf;
 590         int cpu;
 591
 592         for_each_channel_cpu(cpu, chan) {
 593                 buf = channel_get_ring_buffer(&client_config, chan, cpu);
 594                 if (!atomic_long_read(&buf->active_readers))
 595                         return 1;
 596         }
 597         return 0;
 598 }
 599
 600 static
 601 void lttng_buffer_read_close(struct lib_ring_buffer *buf)
 602 {
 603         lib_ring_buffer_release_read(buf);
 604 }
 605
 606 static
 607 int lttng_event_reserve(struct lib_ring_buffer_ctx *ctx,
 608                       uint32_t event_id)
 609 {
 610         struct lttng_kernel_event_recorder *event_recorder = ctx->client_priv;
 611         struct lttng_channel *lttng_chan = event_recorder->chan;
 612         struct lttng_client_ctx client_ctx;
 613         int ret, cpu;
 614
 615         cpu = lib_ring_buffer_get_cpu(&client_config);
 616         if (unlikely(cpu < 0))
 617                 return -EPERM;
 618         memset(&ctx->priv, 0, sizeof(ctx->priv));
 619         ctx->priv.chan = lttng_chan->chan;
 620         ctx->priv.reserve_cpu = cpu;
 621
 622         /* Compute internal size of context structures. */
 623         ctx_get_struct_size(lttng_chan->ctx, &client_ctx.packet_context_len, lttng_chan, ctx);
 624
 625         switch (lttng_chan->header_type) {
 626         case 1: /* compact */
 627                 if (event_id > 30)
 628                         ctx->priv.rflags |= LTTNG_RFLAG_EXTENDED;
 629                 break;
 630         case 2: /* large */
 631                 if (event_id > 65534)
 632                         ctx->priv.rflags |= LTTNG_RFLAG_EXTENDED;
 633                 break;
 634         default:
 635                 WARN_ON_ONCE(1);
 636         }
 637
 638         ret = lib_ring_buffer_reserve(&client_config, ctx, &client_ctx);
 639         if (unlikely(ret))
 640                 goto put;
 641         lib_ring_buffer_backend_get_pages(&client_config, ctx,
 642                         &ctx->priv.backend_pages);
 643         lttng_write_event_header(&client_config, ctx, event_id);
 644         return 0;
 645 put:
 646         lib_ring_buffer_put_cpu(&client_config);
 647         return ret;
 648 }
 649
 650 static
 651 void lttng_event_commit(struct lib_ring_buffer_ctx *ctx)
 652 {
 653         lib_ring_buffer_commit(&client_config, ctx);
 654         lib_ring_buffer_put_cpu(&client_config);
 655 }
 656
 657 static
 658 void lttng_event_write(struct lib_ring_buffer_ctx *ctx, const void *src,
 659                      size_t len)
 660 {
 661         lib_ring_buffer_write(&client_config, ctx, src, len);
 662 }
 663
 664 static
 665 void lttng_event_write_from_user(struct lib_ring_buffer_ctx *ctx,
 666                                const void __user *src, size_t len)
 667 {
 668         lib_ring_buffer_copy_from_user_inatomic(&client_config, ctx, src, len);
 669 }
 670
 671 static
 672 void lttng_event_memset(struct lib_ring_buffer_ctx *ctx,
 673                 int c, size_t len)
 674 {
 675         lib_ring_buffer_memset(&client_config, ctx, c, len);
 676 }
 677
 678 static
 679 void lttng_event_strcpy(struct lib_ring_buffer_ctx *ctx, const char *src,
 680                 size_t len)
 681 {
 682         lib_ring_buffer_strcpy(&client_config, ctx, src, len, '#');
 683 }
 684
 685 static
 686 void lttng_event_strcpy_from_user(struct lib_ring_buffer_ctx *ctx,
 687                 const char __user *src, size_t len)
 688 {
 689         lib_ring_buffer_strcpy_from_user_inatomic(&client_config, ctx, src,
 690                         len, '#');
 691 }
 692
 693 static
 694 wait_queue_head_t *lttng_get_writer_buf_wait_queue(struct channel *chan, int cpu)
 695 {
 696         struct lib_ring_buffer *buf = channel_get_ring_buffer(&client_config,
 697                                         chan, cpu);
 698         return &buf->write_wait;
 699 }
 700
 701 static
 702 wait_queue_head_t *lttng_get_hp_wait_queue(struct channel *chan)
 703 {
 704         return &chan->hp_wait;
 705 }
 706
 707 static
 708 int lttng_is_finalized(struct channel *chan)
 709 {
 710         return lib_ring_buffer_channel_is_finalized(chan);
 711 }
 712
 713 static
 714 int lttng_is_disabled(struct channel *chan)
 715 {
 716         return lib_ring_buffer_channel_is_disabled(chan);
 717 }
 718
 719 static struct lttng_transport lttng_relay_transport = {
 720         .name = "relay-" RING_BUFFER_MODE_TEMPLATE_STRING,
 721         .owner = THIS_MODULE,
 722         .ops = {
 723                 .channel_create = _channel_create,
 724                 .channel_destroy = lttng_channel_destroy,
 725                 .buffer_read_open = lttng_buffer_read_open,
 726                 .buffer_has_read_closed_stream =
 727                         lttng_buffer_has_read_closed_stream,
 728                 .buffer_read_close = lttng_buffer_read_close,
 729                 .event_reserve = lttng_event_reserve,
 730                 .event_commit = lttng_event_commit,
 731                 .event_write = lttng_event_write,
 732                 .event_write_from_user = lttng_event_write_from_user,
 733                 .event_memset = lttng_event_memset,
 734                 .event_strcpy = lttng_event_strcpy,
 735                 .event_strcpy_from_user = lttng_event_strcpy_from_user,
 736                 .packet_avail_size = NULL,      /* Would be racy anyway */
 737                 .get_writer_buf_wait_queue = lttng_get_writer_buf_wait_queue,
 738                 .get_hp_wait_queue = lttng_get_hp_wait_queue,
 739                 .is_finalized = lttng_is_finalized,
 740                 .is_disabled = lttng_is_disabled,
 741                 .timestamp_begin = client_timestamp_begin,
 742                 .timestamp_end = client_timestamp_end,
 743                 .events_discarded = client_events_discarded,
 744                 .content_size = client_content_size,
 745                 .packet_size = client_packet_size,
 746                 .stream_id = client_stream_id,
 747                 .current_timestamp = client_current_timestamp,
 748                 .sequence_number = client_sequence_number,
 749                 .instance_id = client_instance_id,
 750         },
 751 };
 752
 753 static int __init lttng_ring_buffer_client_init(void)
 754 {
 755         /*
 756          * This vmalloc sync all also takes care of the lib ring buffer
 757          * vmalloc'd module pages when it is built as a module into LTTng.
 758          */
 759         wrapper_vmalloc_sync_mappings();
 760         lttng_transport_register(&lttng_relay_transport);
 761         return 0;
 762 }
 763
 764 module_init(lttng_ring_buffer_client_init);
 765
 766 static void __exit lttng_ring_buffer_client_exit(void)
 767 {
 768         lttng_transport_unregister(&lttng_relay_transport);
 769 }
 770
 771 module_exit(lttng_ring_buffer_client_exit);
 772
 773 MODULE_LICENSE("GPL and additional rights");
 774 MODULE_AUTHOR("Mathieu Desnoyers <mathieu.desnoyers@efficios.com>");
 775 MODULE_DESCRIPTION("LTTng ring buffer " RING_BUFFER_MODE_TEMPLATE_STRING
 776                    " client");
 777 MODULE_VERSION(__stringify(LTTNG_MODULES_MAJOR_VERSION) "."
 778         __stringify(LTTNG_MODULES_MINOR_VERSION) "."
 779         __stringify(LTTNG_MODULES_PATCHLEVEL_VERSION)
 780         LTTNG_MODULES_EXTRAVERSION);