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