lttng-ring-buffer-client.h

   1 /* SPDX-License-Identifier: (GPL-2.0 or LGPL-2.1)
   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 <lib/bitfield.h>
  13 #include <wrapper/vmalloc.h>    /* for wrapper_vmalloc_sync_all() */
  14 #include <wrapper/trace-clock.h>
  15 #include <lttng-events.h>
  16 #include <lttng-tracer.h>
  17 #include <wrapper/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_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_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_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         struct lttng_probe_ctx *lttng_probe_ctx = ctx->priv;
 146         struct lttng_event *event = lttng_probe_ctx->event;
 147         size_t orig_offset = offset;
 148         size_t padding;
 149
 150         switch (lttng_chan->header_type) {
 151         case 1: /* compact */
 152                 padding = lib_ring_buffer_align(offset, lttng_alignof(uint32_t));
 153                 offset += padding;
 154                 if (!(ctx->rflags & (RING_BUFFER_RFLAG_FULL_TSC | LTTNG_RFLAG_EXTENDED))) {
 155                         offset += sizeof(uint32_t);     /* id and timestamp */
 156                 } else {
 157                         /* Minimum space taken by LTTNG_COMPACT_EVENT_BITS id */
 158                         offset += (LTTNG_COMPACT_EVENT_BITS + CHAR_BIT - 1) / CHAR_BIT;
 159                         /* Align extended struct on largest member */
 160                         offset += lib_ring_buffer_align(offset, lttng_alignof(uint64_t));
 161                         offset += sizeof(uint32_t);     /* id */
 162                         offset += lib_ring_buffer_align(offset, lttng_alignof(uint64_t));
 163                         offset += sizeof(uint64_t);     /* timestamp */
 164                 }
 165                 break;
 166         case 2: /* large */
 167                 padding = lib_ring_buffer_align(offset, lttng_alignof(uint16_t));
 168                 offset += padding;
 169                 offset += sizeof(uint16_t);
 170                 if (!(ctx->rflags & (RING_BUFFER_RFLAG_FULL_TSC | LTTNG_RFLAG_EXTENDED))) {
 171                         offset += lib_ring_buffer_align(offset, lttng_alignof(uint32_t));
 172                         offset += sizeof(uint32_t);     /* timestamp */
 173                 } else {
 174                         /* Align extended struct on largest member */
 175                         offset += lib_ring_buffer_align(offset, lttng_alignof(uint64_t));
 176                         offset += sizeof(uint32_t);     /* id */
 177                         offset += lib_ring_buffer_align(offset, lttng_alignof(uint64_t));
 178                         offset += sizeof(uint64_t);     /* timestamp */
 179                 }
 180                 break;
 181         default:
 182                 padding = 0;
 183                 WARN_ON_ONCE(1);
 184         }
 185         offset += ctx_get_aligned_size(offset, lttng_chan->ctx,
 186                         client_ctx->packet_context_len);
 187         offset += ctx_get_aligned_size(offset, event->ctx,
 188                         client_ctx->event_context_len);
 189
 190         *pre_header_padding = padding;
 191         return offset - orig_offset;
 192 }
 193
 194 #include <wrapper/ringbuffer/api.h>
 195
 196 static
 197 void lttng_write_event_header_slow(const struct lib_ring_buffer_config *config,
 198                                  struct lib_ring_buffer_ctx *ctx,
 199                                  uint32_t event_id);
 200
 201 /*
 202  * lttng_write_event_header
 203  *
 204  * Writes the event header to the offset (already aligned on 32-bits).
 205  *
 206  * @config: ring buffer instance configuration
 207  * @ctx: reservation context
 208  * @event_id: event ID
 209  */
 210 static __inline__
 211 void lttng_write_event_header(const struct lib_ring_buffer_config *config,
 212                             struct lib_ring_buffer_ctx *ctx,
 213                             uint32_t event_id)
 214 {
 215         struct lttng_channel *lttng_chan = channel_get_private(ctx->chan);
 216         struct lttng_probe_ctx *lttng_probe_ctx = ctx->priv;
 217         struct lttng_event *event = lttng_probe_ctx->event;
 218
 219         if (unlikely(ctx->rflags))
 220                 goto slow_path;
 221
 222         switch (lttng_chan->header_type) {
 223         case 1: /* compact */
 224         {
 225                 uint32_t id_time = 0;
 226
 227                 bt_bitfield_write(&id_time, uint32_t,
 228                                 0,
 229                                 LTTNG_COMPACT_EVENT_BITS,
 230                                 event_id);
 231                 bt_bitfield_write(&id_time, uint32_t,
 232                                 LTTNG_COMPACT_EVENT_BITS,
 233                                 LTTNG_COMPACT_TSC_BITS,
 234                                 ctx->tsc);
 235                 lib_ring_buffer_write(config, ctx, &id_time, sizeof(id_time));
 236                 break;
 237         }
 238         case 2: /* large */
 239         {
 240                 uint32_t timestamp = (uint32_t) ctx->tsc;
 241                 uint16_t id = event_id;
 242
 243                 lib_ring_buffer_write(config, ctx, &id, sizeof(id));
 244                 lib_ring_buffer_align_ctx(ctx, lttng_alignof(uint32_t));
 245                 lib_ring_buffer_write(config, ctx, &timestamp, sizeof(timestamp));
 246                 break;
 247         }
 248         default:
 249                 WARN_ON_ONCE(1);
 250         }
 251
 252         ctx_record(ctx, lttng_chan, lttng_chan->ctx);
 253         ctx_record(ctx, lttng_chan, event->ctx);
 254         lib_ring_buffer_align_ctx(ctx, ctx->largest_align);
 255
 256         return;
 257
 258 slow_path:
 259         lttng_write_event_header_slow(config, ctx, event_id);
 260 }
 261
 262 static
 263 void lttng_write_event_header_slow(const struct lib_ring_buffer_config *config,
 264                                  struct lib_ring_buffer_ctx *ctx,
 265                                  uint32_t event_id)
 266 {
 267         struct lttng_channel *lttng_chan = channel_get_private(ctx->chan);
 268         struct lttng_probe_ctx *lttng_probe_ctx = ctx->priv;
 269         struct lttng_event *event = lttng_probe_ctx->event;
 270
 271         switch (lttng_chan->header_type) {
 272         case 1: /* compact */
 273                 if (!(ctx->rflags & (RING_BUFFER_RFLAG_FULL_TSC | LTTNG_RFLAG_EXTENDED))) {
 274                         uint32_t id_time = 0;
 275
 276                         bt_bitfield_write(&id_time, uint32_t,
 277                                         0,
 278                                         LTTNG_COMPACT_EVENT_BITS,
 279                                         event_id);
 280                         bt_bitfield_write(&id_time, uint32_t,
 281                                         LTTNG_COMPACT_EVENT_BITS,
 282                                         LTTNG_COMPACT_TSC_BITS, ctx->tsc);
 283                         lib_ring_buffer_write(config, ctx, &id_time, sizeof(id_time));
 284                 } else {
 285                         uint8_t id = 0;
 286                         uint64_t timestamp = ctx->tsc;
 287
 288                         bt_bitfield_write(&id, uint8_t,
 289                                         0,
 290                                         LTTNG_COMPACT_EVENT_BITS,
 291                                         31);
 292                         lib_ring_buffer_write(config, ctx, &id, sizeof(id));
 293                         /* Align extended struct on largest member */
 294                         lib_ring_buffer_align_ctx(ctx, lttng_alignof(uint64_t));
 295                         lib_ring_buffer_write(config, ctx, &event_id, sizeof(event_id));
 296                         lib_ring_buffer_align_ctx(ctx, lttng_alignof(uint64_t));
 297                         lib_ring_buffer_write(config, ctx, &timestamp, sizeof(timestamp));
 298                 }
 299                 break;
 300         case 2: /* large */
 301         {
 302                 if (!(ctx->rflags & (RING_BUFFER_RFLAG_FULL_TSC | LTTNG_RFLAG_EXTENDED))) {
 303                         uint32_t timestamp = (uint32_t) ctx->tsc;
 304                         uint16_t id = event_id;
 305
 306                         lib_ring_buffer_write(config, ctx, &id, sizeof(id));
 307                         lib_ring_buffer_align_ctx(ctx, lttng_alignof(uint32_t));
 308                         lib_ring_buffer_write(config, ctx, &timestamp, sizeof(timestamp));
 309                 } else {
 310                         uint16_t id = 65535;
 311                         uint64_t timestamp = ctx->tsc;
 312
 313                         lib_ring_buffer_write(config, ctx, &id, sizeof(id));
 314                         /* Align extended struct on largest member */
 315                         lib_ring_buffer_align_ctx(ctx, lttng_alignof(uint64_t));
 316                         lib_ring_buffer_write(config, ctx, &event_id, sizeof(event_id));
 317                         lib_ring_buffer_align_ctx(ctx, lttng_alignof(uint64_t));
 318                         lib_ring_buffer_write(config, ctx, &timestamp, sizeof(timestamp));
 319                 }
 320                 break;
 321         }
 322         default:
 323                 WARN_ON_ONCE(1);
 324         }
 325         ctx_record(ctx, lttng_chan, lttng_chan->ctx);
 326         ctx_record(ctx, lttng_chan, event->ctx);
 327         lib_ring_buffer_align_ctx(ctx, ctx->largest_align);
 328 }
 329
 330 static const struct lib_ring_buffer_config client_config;
 331
 332 static u64 client_ring_buffer_clock_read(struct channel *chan)
 333 {
 334         return lib_ring_buffer_clock_read(chan);
 335 }
 336
 337 static
 338 size_t client_record_header_size(const struct lib_ring_buffer_config *config,
 339                                  struct channel *chan, size_t offset,
 340                                  size_t *pre_header_padding,
 341                                  struct lib_ring_buffer_ctx *ctx,
 342                                  void *client_ctx)
 343 {
 344         return record_header_size(config, chan, offset,
 345                                   pre_header_padding, ctx, client_ctx);
 346 }
 347
 348 /**
 349  * client_packet_header_size - called on buffer-switch to a new sub-buffer
 350  *
 351  * Return header size without padding after the structure. Don't use packed
 352  * structure because gcc generates inefficient code on some architectures
 353  * (powerpc, mips..)
 354  */
 355 static size_t client_packet_header_size(void)
 356 {
 357         return offsetof(struct packet_header, ctx.header_end);
 358 }
 359
 360 static void client_buffer_begin(struct lib_ring_buffer *buf, u64 tsc,
 361                                 unsigned int subbuf_idx)
 362 {
 363         struct channel *chan = buf->backend.chan;
 364         struct packet_header *header =
 365                 (struct packet_header *)
 366                         lib_ring_buffer_offset_address(&buf->backend,
 367                                 subbuf_idx * chan->backend.subbuf_size);
 368         struct lttng_channel *lttng_chan = channel_get_private(chan);
 369         struct lttng_session *session = lttng_chan->session;
 370
 371         header->magic = CTF_MAGIC_NUMBER;
 372         memcpy(header->uuid, session->uuid.b, sizeof(session->uuid));
 373         header->stream_id = lttng_chan->id;
 374         header->stream_instance_id = buf->backend.cpu;
 375         header->ctx.timestamp_begin = tsc;
 376         header->ctx.timestamp_end = 0;
 377         header->ctx.content_size = ~0ULL; /* for debugging */
 378         header->ctx.packet_size = ~0ULL;
 379         header->ctx.packet_seq_num = chan->backend.num_subbuf * \
 380                                      buf->backend.buf_cnt[subbuf_idx].seq_cnt + \
 381                                      subbuf_idx;
 382         header->ctx.events_discarded = 0;
 383         header->ctx.cpu_id = buf->backend.cpu;
 384 }
 385
 386 /*
 387  * offset is assumed to never be 0 here : never deliver a completely empty
 388  * subbuffer. data_size is between 1 and subbuf_size.
 389  */
 390 static void client_buffer_end(struct lib_ring_buffer *buf, u64 tsc,
 391                               unsigned int subbuf_idx, unsigned long data_size)
 392 {
 393         struct channel *chan = buf->backend.chan;
 394         struct packet_header *header =
 395                 (struct packet_header *)
 396                         lib_ring_buffer_offset_address(&buf->backend,
 397                                 subbuf_idx * chan->backend.subbuf_size);
 398         unsigned long records_lost = 0;
 399
 400         header->ctx.timestamp_end = tsc;
 401         header->ctx.content_size =
 402                 (uint64_t) data_size * CHAR_BIT;                /* in bits */
 403         header->ctx.packet_size =
 404                 (uint64_t) PAGE_ALIGN(data_size) * CHAR_BIT;    /* in bits */
 405         records_lost += lib_ring_buffer_get_records_lost_full(&client_config, buf);
 406         records_lost += lib_ring_buffer_get_records_lost_wrap(&client_config, buf);
 407         records_lost += lib_ring_buffer_get_records_lost_big(&client_config, buf);
 408         header->ctx.events_discarded = records_lost;
 409 }
 410
 411 static int client_buffer_create(struct lib_ring_buffer *buf, void *priv,
 412                                 int cpu, const char *name)
 413 {
 414         return 0;
 415 }
 416
 417 static void client_buffer_finalize(struct lib_ring_buffer *buf, void *priv, int cpu)
 418 {
 419 }
 420
 421 static struct packet_header *client_packet_header(
 422                 const struct lib_ring_buffer_config *config,
 423                 struct lib_ring_buffer *buf)
 424 {
 425         return lib_ring_buffer_read_offset_address(&buf->backend, 0);
 426 }
 427
 428 static int client_timestamp_begin(const struct lib_ring_buffer_config *config,
 429                 struct lib_ring_buffer *buf,
 430                 uint64_t *timestamp_begin)
 431 {
 432         struct packet_header *header = client_packet_header(config, buf);
 433         *timestamp_begin = header->ctx.timestamp_begin;
 434
 435         return 0;
 436 }
 437
 438 static int client_timestamp_end(const struct lib_ring_buffer_config *config,
 439                         struct lib_ring_buffer *buf,
 440                         uint64_t *timestamp_end)
 441 {
 442         struct packet_header *header = client_packet_header(config, buf);
 443         *timestamp_end = header->ctx.timestamp_end;
 444
 445         return 0;
 446 }
 447
 448 static int client_events_discarded(const struct lib_ring_buffer_config *config,
 449                         struct lib_ring_buffer *buf,
 450                         uint64_t *events_discarded)
 451 {
 452         struct packet_header *header = client_packet_header(config, buf);
 453         *events_discarded = header->ctx.events_discarded;
 454
 455         return 0;
 456 }
 457
 458 static int client_content_size(const struct lib_ring_buffer_config *config,
 459                         struct lib_ring_buffer *buf,
 460                         uint64_t *content_size)
 461 {
 462         struct packet_header *header = client_packet_header(config, buf);
 463         *content_size = header->ctx.content_size;
 464
 465         return 0;
 466 }
 467
 468 static int client_packet_size(const struct lib_ring_buffer_config *config,
 469                         struct lib_ring_buffer *buf,
 470                         uint64_t *packet_size)
 471 {
 472         struct packet_header *header = client_packet_header(config, buf);
 473         *packet_size = header->ctx.packet_size;
 474
 475         return 0;
 476 }
 477
 478 static int client_stream_id(const struct lib_ring_buffer_config *config,
 479                         struct lib_ring_buffer *buf,
 480                         uint64_t *stream_id)
 481 {
 482         struct channel *chan = buf->backend.chan;
 483         struct lttng_channel *lttng_chan = channel_get_private(chan);
 484
 485         *stream_id = lttng_chan->id;
 486         return 0;
 487 }
 488
 489 static int client_current_timestamp(const struct lib_ring_buffer_config *config,
 490                 struct lib_ring_buffer *bufb,
 491                 uint64_t *ts)
 492 {
 493         *ts = config->cb.ring_buffer_clock_read(bufb->backend.chan);
 494
 495         return 0;
 496 }
 497
 498 static int client_sequence_number(const struct lib_ring_buffer_config *config,
 499                         struct lib_ring_buffer *buf,
 500                         uint64_t *seq)
 501 {
 502         struct packet_header *header = client_packet_header(config, buf);
 503
 504         *seq = header->ctx.packet_seq_num;
 505
 506         return 0;
 507 }
 508
 509 static
 510 int client_instance_id(const struct lib_ring_buffer_config *config,
 511                 struct lib_ring_buffer *buf,
 512                 uint64_t *id)
 513 {
 514         *id = buf->backend.cpu;
 515
 516         return 0;
 517 }
 518
 519 static const struct lib_ring_buffer_config client_config = {
 520         .cb.ring_buffer_clock_read = client_ring_buffer_clock_read,
 521         .cb.record_header_size = client_record_header_size,
 522         .cb.subbuffer_header_size = client_packet_header_size,
 523         .cb.buffer_begin = client_buffer_begin,
 524         .cb.buffer_end = client_buffer_end,
 525         .cb.buffer_create = client_buffer_create,
 526         .cb.buffer_finalize = client_buffer_finalize,
 527
 528         .tsc_bits = LTTNG_COMPACT_TSC_BITS,
 529         .alloc = RING_BUFFER_ALLOC_PER_CPU,
 530         .sync = RING_BUFFER_SYNC_PER_CPU,
 531         .mode = RING_BUFFER_MODE_TEMPLATE,
 532         .backend = RING_BUFFER_PAGE,
 533         .output = RING_BUFFER_OUTPUT_TEMPLATE,
 534         .oops = RING_BUFFER_OOPS_CONSISTENCY,
 535         .ipi = RING_BUFFER_IPI_BARRIER,
 536         .wakeup = RING_BUFFER_WAKEUP_BY_TIMER,
 537 };
 538
 539 static
 540 void release_priv_ops(void *priv_ops)
 541 {
 542         module_put(THIS_MODULE);
 543 }
 544
 545 static
 546 void lttng_channel_destroy(struct channel *chan)
 547 {
 548         channel_destroy(chan);
 549 }
 550
 551 static
 552 struct channel *_channel_create(const char *name,
 553                                 struct lttng_channel *lttng_chan, void *buf_addr,
 554                                 size_t subbuf_size, size_t num_subbuf,
 555                                 unsigned int switch_timer_interval,
 556                                 unsigned int read_timer_interval)
 557 {
 558         struct channel *chan;
 559
 560         chan = channel_create(&client_config, name, lttng_chan, buf_addr,
 561                               subbuf_size, num_subbuf, switch_timer_interval,
 562                               read_timer_interval);
 563         if (chan) {
 564                 /*
 565                  * Ensure this module is not unloaded before we finish
 566                  * using lttng_relay_transport.ops.
 567                  */
 568                 if (!try_module_get(THIS_MODULE)) {
 569                         printk(KERN_WARNING "LTT : Can't lock transport module.\n");
 570                         goto error;
 571                 }
 572                 chan->backend.priv_ops = &lttng_relay_transport.ops;
 573                 chan->backend.release_priv_ops = release_priv_ops;
 574         }
 575         return chan;
 576
 577 error:
 578         lttng_channel_destroy(chan);
 579         return NULL;
 580 }
 581
 582 static
 583 struct lib_ring_buffer *lttng_buffer_read_open(struct channel *chan)
 584 {
 585         struct lib_ring_buffer *buf;
 586         int cpu;
 587
 588         for_each_channel_cpu(cpu, chan) {
 589                 buf = channel_get_ring_buffer(&client_config, chan, cpu);
 590                 if (!lib_ring_buffer_open_read(buf))
 591                         return buf;
 592         }
 593         return NULL;
 594 }
 595
 596 static
 597 int lttng_buffer_has_read_closed_stream(struct channel *chan)
 598 {
 599         struct lib_ring_buffer *buf;
 600         int cpu;
 601
 602         for_each_channel_cpu(cpu, chan) {
 603                 buf = channel_get_ring_buffer(&client_config, chan, cpu);
 604                 if (!atomic_long_read(&buf->active_readers))
 605                         return 1;
 606         }
 607         return 0;
 608 }
 609
 610 static
 611 void lttng_buffer_read_close(struct lib_ring_buffer *buf)
 612 {
 613         lib_ring_buffer_release_read(buf);
 614 }
 615
 616 static
 617 int lttng_event_reserve(struct lib_ring_buffer_ctx *ctx,
 618                       uint32_t event_id)
 619 {
 620         struct lttng_channel *lttng_chan = channel_get_private(ctx->chan);
 621         struct lttng_probe_ctx *lttng_probe_ctx = ctx->priv;
 622         struct lttng_event *event = lttng_probe_ctx->event;
 623         struct lttng_client_ctx client_ctx;
 624         int ret, cpu;
 625
 626         cpu = lib_ring_buffer_get_cpu(&client_config);
 627         if (unlikely(cpu < 0))
 628                 return -EPERM;
 629         ctx->cpu = cpu;
 630
 631         /* Compute internal size of context structures. */
 632         ctx_get_struct_size(lttng_chan->ctx, &client_ctx.packet_context_len, lttng_chan, ctx);
 633         ctx_get_struct_size(event->ctx, &client_ctx.event_context_len, lttng_chan, ctx);
 634
 635         switch (lttng_chan->header_type) {
 636         case 1: /* compact */
 637                 if (event_id > 30)
 638                         ctx->rflags |= LTTNG_RFLAG_EXTENDED;
 639                 break;
 640         case 2: /* large */
 641                 if (event_id > 65534)
 642                         ctx->rflags |= LTTNG_RFLAG_EXTENDED;
 643                 break;
 644         default:
 645                 WARN_ON_ONCE(1);
 646         }
 647
 648         ret = lib_ring_buffer_reserve(&client_config, ctx, &client_ctx);
 649         if (unlikely(ret))
 650                 goto put;
 651         lib_ring_buffer_backend_get_pages(&client_config, ctx,
 652                         &ctx->backend_pages);
 653         lttng_write_event_header(&client_config, ctx, event_id);
 654         return 0;
 655 put:
 656         lib_ring_buffer_put_cpu(&client_config);
 657         return ret;
 658 }
 659
 660 static
 661 void lttng_event_commit(struct lib_ring_buffer_ctx *ctx)
 662 {
 663         lib_ring_buffer_commit(&client_config, ctx);
 664         lib_ring_buffer_put_cpu(&client_config);
 665 }
 666
 667 static
 668 void lttng_event_write(struct lib_ring_buffer_ctx *ctx, const void *src,
 669                      size_t len)
 670 {
 671         lib_ring_buffer_write(&client_config, ctx, src, len);
 672 }
 673
 674 static
 675 void lttng_event_write_from_user(struct lib_ring_buffer_ctx *ctx,
 676                                const void __user *src, size_t len)
 677 {
 678         lib_ring_buffer_copy_from_user_inatomic(&client_config, ctx, src, len);
 679 }
 680
 681 static
 682 void lttng_event_memset(struct lib_ring_buffer_ctx *ctx,
 683                 int c, size_t len)
 684 {
 685         lib_ring_buffer_memset(&client_config, ctx, c, len);
 686 }
 687
 688 static
 689 void lttng_event_strcpy(struct lib_ring_buffer_ctx *ctx, const char *src,
 690                 size_t len)
 691 {
 692         lib_ring_buffer_strcpy(&client_config, ctx, src, len, '#');
 693 }
 694
 695 static
 696 void lttng_event_strcpy_from_user(struct lib_ring_buffer_ctx *ctx,
 697                 const char __user *src, size_t len)
 698 {
 699         lib_ring_buffer_strcpy_from_user_inatomic(&client_config, ctx, src,
 700                         len, '#');
 701 }
 702
 703 static
 704 wait_queue_head_t *lttng_get_writer_buf_wait_queue(struct channel *chan, int cpu)
 705 {
 706         struct lib_ring_buffer *buf = channel_get_ring_buffer(&client_config,
 707                                         chan, cpu);
 708         return &buf->write_wait;
 709 }
 710
 711 static
 712 wait_queue_head_t *lttng_get_hp_wait_queue(struct channel *chan)
 713 {
 714         return &chan->hp_wait;
 715 }
 716
 717 static
 718 int lttng_is_finalized(struct channel *chan)
 719 {
 720         return lib_ring_buffer_channel_is_finalized(chan);
 721 }
 722
 723 static
 724 int lttng_is_disabled(struct channel *chan)
 725 {
 726         return lib_ring_buffer_channel_is_disabled(chan);
 727 }
 728
 729 static struct lttng_transport lttng_relay_transport = {
 730         .name = "relay-" RING_BUFFER_MODE_TEMPLATE_STRING,
 731         .owner = THIS_MODULE,
 732         .ops = {
 733                 .channel_create = _channel_create,
 734                 .channel_destroy = lttng_channel_destroy,
 735                 .buffer_read_open = lttng_buffer_read_open,
 736                 .buffer_has_read_closed_stream =
 737                         lttng_buffer_has_read_closed_stream,
 738                 .buffer_read_close = lttng_buffer_read_close,
 739                 .event_reserve = lttng_event_reserve,
 740                 .event_commit = lttng_event_commit,
 741                 .event_write = lttng_event_write,
 742                 .event_write_from_user = lttng_event_write_from_user,
 743                 .event_memset = lttng_event_memset,
 744                 .event_strcpy = lttng_event_strcpy,
 745                 .event_strcpy_from_user = lttng_event_strcpy_from_user,
 746                 .packet_avail_size = NULL,      /* Would be racy anyway */
 747                 .get_writer_buf_wait_queue = lttng_get_writer_buf_wait_queue,
 748                 .get_hp_wait_queue = lttng_get_hp_wait_queue,
 749                 .is_finalized = lttng_is_finalized,
 750                 .is_disabled = lttng_is_disabled,
 751                 .timestamp_begin = client_timestamp_begin,
 752                 .timestamp_end = client_timestamp_end,
 753                 .events_discarded = client_events_discarded,
 754                 .content_size = client_content_size,
 755                 .packet_size = client_packet_size,
 756                 .stream_id = client_stream_id,
 757                 .current_timestamp = client_current_timestamp,
 758                 .sequence_number = client_sequence_number,
 759                 .instance_id = client_instance_id,
 760         },
 761 };
 762
 763 static int __init lttng_ring_buffer_client_init(void)
 764 {
 765         /*
 766          * This vmalloc sync all also takes care of the lib ring buffer
 767          * vmalloc'd module pages when it is built as a module into LTTng.
 768          */
 769         wrapper_vmalloc_sync_all();
 770         lttng_transport_register(&lttng_relay_transport);
 771         return 0;
 772 }
 773
 774 module_init(lttng_ring_buffer_client_init);
 775
 776 static void __exit lttng_ring_buffer_client_exit(void)
 777 {
 778         lttng_transport_unregister(&lttng_relay_transport);
 779 }
 780
 781 module_exit(lttng_ring_buffer_client_exit);
 782
 783 MODULE_LICENSE("GPL and additional rights");
 784 MODULE_AUTHOR("Mathieu Desnoyers <mathieu.desnoyers@efficios.com>");
 785 MODULE_DESCRIPTION("LTTng ring buffer " RING_BUFFER_MODE_TEMPLATE_STRING
 786                    " client");
 787 MODULE_VERSION(__stringify(LTTNG_MODULES_MAJOR_VERSION) "."
 788         __stringify(LTTNG_MODULES_MINOR_VERSION) "."
 789         __stringify(LTTNG_MODULES_PATCHLEVEL_VERSION)
 790         LTTNG_MODULES_EXTRAVERSION);