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