src/lttng-ring-buffer-client.h

   1 /* SPDX-License-Identifier: (GPL-2.0-only or LGPL-2.1-only)
   2  *
   3  * lttng-ring-buffer-client.h
   4  *
   5  * LTTng lib ring buffer client template.
   6  *
   7  * Copyright (C) 2010-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   8  */
   9
  10 #include <linux/module.h>
  11 #include <linux/types.h>
  12 #include <lttng/bitfield.h>
  13 #include <wrapper/vmalloc.h>    /* for wrapper_vmalloc_sync_mappings() */
  14 #include <wrapper/trace-clock.h>
  15 #include <lttng/events.h>
  16 #include <lttng/tracer.h>
  17 #include <ringbuffer/frontend_types.h>
  18
  19 #define LTTNG_COMPACT_EVENT_BITS        5
  20 #define LTTNG_COMPACT_TSC_BITS          27
  21
  22 static struct lttng_transport lttng_relay_transport;
  23
  24 /*
  25  * Keep the natural field alignment for _each field_ within this structure if
  26  * you ever add/remove a field from this header. Packed attribute is not used
  27  * because gcc generates poor code on at least powerpc and mips. Don't ever
  28  * let gcc add padding between the structure elements.
  29  *
  30  * The guarantee we have with timestamps is that all the events in a
  31  * packet are included (inclusive) within the begin/end timestamps of
  32  * the packet. Another guarantee we have is that the "timestamp begin",
  33  * as well as the event timestamps, are monotonically increasing (never
  34  * decrease) when moving forward in a stream (physically). But this
  35  * guarantee does not apply to "timestamp end", because it is sampled at
  36  * commit time, which is not ordered with respect to space reservation.
  37  */
  38
  39 struct packet_header {
  40         /* Trace packet header */
  41         uint32_t magic;                 /*
  42                                          * Trace magic number.
  43                                          * contains endianness information.
  44                                          */
  45         uint8_t uuid[16];
  46         uint32_t stream_id;
  47         uint64_t stream_instance_id;
  48
  49         struct {
  50                 /* Stream packet context */
  51                 uint64_t timestamp_begin;       /* Cycle count at subbuffer start */
  52                 uint64_t timestamp_end;         /* Cycle count at subbuffer end */
  53                 uint64_t content_size;          /* Size of data in subbuffer */
  54                 uint64_t packet_size;           /* Subbuffer size (include padding) */
  55                 uint64_t packet_seq_num;        /* Packet sequence number */
  56                 unsigned long events_discarded; /*
  57                                                  * Events lost in this subbuffer since
  58                                                  * the beginning of the trace.
  59                                                  * (may overflow)
  60                                                  */
  61                 uint32_t cpu_id;                /* CPU id associated with stream */
  62                 uint8_t header_end;             /* End of header */
  63         } ctx;
  64 };
  65
  66 struct lttng_client_ctx {
  67         size_t packet_context_len;
  68         size_t event_context_len;
  69 };
  70
  71 static inline notrace u64 lib_ring_buffer_clock_read(struct channel *chan)
  72 {
  73         return trace_clock_read64();
  74 }
  75
  76 static inline
  77 size_t ctx_get_aligned_size(size_t offset, struct lttng_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_event_container *container = channel_get_private(chan);
 145         struct lttng_channel *lttng_chan = lttng_event_container_get_channel(container);
 146         struct lttng_probe_ctx *lttng_probe_ctx = ctx->priv;
 147         struct lttng_event *event = lttng_probe_ctx->event;
 148         size_t orig_offset = offset;
 149         size_t padding;
 150
 151         switch (lttng_chan->header_type) {
 152         case 1: /* compact */
 153                 padding = lib_ring_buffer_align(offset, lttng_alignof(uint32_t));
 154                 offset += padding;
 155                 if (!(ctx->rflags & (RING_BUFFER_RFLAG_FULL_TSC | LTTNG_RFLAG_EXTENDED))) {
 156                         offset += sizeof(uint32_t);     /* id and timestamp */
 157                 } else {
 158                         /* Minimum space taken by LTTNG_COMPACT_EVENT_BITS id */
 159                         offset += (LTTNG_COMPACT_EVENT_BITS + CHAR_BIT - 1) / CHAR_BIT;
 160                         /* Align extended struct on largest member */
 161                         offset += lib_ring_buffer_align(offset, lttng_alignof(uint64_t));
 162                         offset += sizeof(uint32_t);     /* id */
 163                         offset += lib_ring_buffer_align(offset, lttng_alignof(uint64_t));
 164                         offset += sizeof(uint64_t);     /* timestamp */
 165                 }
 166                 break;
 167         case 2: /* large */
 168                 padding = lib_ring_buffer_align(offset, lttng_alignof(uint16_t));
 169                 offset += padding;
 170                 offset += sizeof(uint16_t);
 171                 if (!(ctx->rflags & (RING_BUFFER_RFLAG_FULL_TSC | LTTNG_RFLAG_EXTENDED))) {
 172                         offset += lib_ring_buffer_align(offset, lttng_alignof(uint32_t));
 173                         offset += sizeof(uint32_t);     /* timestamp */
 174                 } else {
 175                         /* Align extended struct on largest member */
 176                         offset += lib_ring_buffer_align(offset, lttng_alignof(uint64_t));
 177                         offset += sizeof(uint32_t);     /* id */
 178                         offset += lib_ring_buffer_align(offset, lttng_alignof(uint64_t));
 179                         offset += sizeof(uint64_t);     /* timestamp */
 180                 }
 181                 break;
 182         default:
 183                 padding = 0;
 184                 WARN_ON_ONCE(1);
 185         }
 186         offset += ctx_get_aligned_size(offset, lttng_chan->ctx,
 187                         client_ctx->packet_context_len);
 188         offset += ctx_get_aligned_size(offset, event->ctx,
 189                         client_ctx->event_context_len);
 190
 191         *pre_header_padding = padding;
 192         return offset - orig_offset;
 193 }
 194
 195 #include <ringbuffer/api.h>
 196
 197 static
 198 void lttng_write_event_header_slow(const struct lib_ring_buffer_config *config,
 199                                  struct lib_ring_buffer_ctx *ctx,
 200                                  uint32_t event_id);
 201
 202 /*
 203  * lttng_write_event_header
 204  *
 205  * Writes the event header to the offset (already aligned on 32-bits).
 206  *
 207  * @config: ring buffer instance configuration
 208  * @ctx: reservation context
 209  * @event_id: event ID
 210  */
 211 static __inline__
 212 void lttng_write_event_header(const struct lib_ring_buffer_config *config,
 213                             struct lib_ring_buffer_ctx *ctx,
 214                             uint32_t event_id)
 215 {
 216         struct lttng_event_container *container = channel_get_private(ctx->chan);
 217         struct lttng_channel *lttng_chan = lttng_event_container_get_channel(container);
 218         struct lttng_probe_ctx *lttng_probe_ctx = ctx->priv;
 219         struct lttng_event *event = lttng_probe_ctx->event;
 220
 221         if (unlikely(ctx->rflags))
 222                 goto slow_path;
 223
 224         switch (lttng_chan->header_type) {
 225         case 1: /* compact */
 226         {
 227                 uint32_t id_time = 0;
 228
 229                 bt_bitfield_write(&id_time, uint32_t,
 230                                 0,
 231                                 LTTNG_COMPACT_EVENT_BITS,
 232                                 event_id);
 233                 bt_bitfield_write(&id_time, uint32_t,
 234                                 LTTNG_COMPACT_EVENT_BITS,
 235                                 LTTNG_COMPACT_TSC_BITS,
 236                                 ctx->tsc);
 237                 lib_ring_buffer_write(config, ctx, &id_time, sizeof(id_time));
 238                 break;
 239         }
 240         case 2: /* large */
 241         {
 242                 uint32_t timestamp = (uint32_t) ctx->tsc;
 243                 uint16_t id = event_id;
 244
 245                 lib_ring_buffer_write(config, ctx, &id, sizeof(id));
 246                 lib_ring_buffer_align_ctx(ctx, lttng_alignof(uint32_t));
 247                 lib_ring_buffer_write(config, ctx, &timestamp, sizeof(timestamp));
 248                 break;
 249         }
 250         default:
 251                 WARN_ON_ONCE(1);
 252         }
 253
 254         ctx_record(ctx, lttng_chan, lttng_chan->ctx);
 255         ctx_record(ctx, lttng_chan, event->ctx);
 256         lib_ring_buffer_align_ctx(ctx, ctx->largest_align);
 257
 258         return;
 259
 260 slow_path:
 261         lttng_write_event_header_slow(config, ctx, event_id);
 262 }
 263
 264 static
 265 void lttng_write_event_header_slow(const struct lib_ring_buffer_config *config,
 266                                  struct lib_ring_buffer_ctx *ctx,
 267                                  uint32_t event_id)
 268 {
 269         struct lttng_event_container *container = channel_get_private(ctx->chan);
 270         struct lttng_channel *lttng_chan = lttng_event_container_get_channel(container);
 271         struct lttng_probe_ctx *lttng_probe_ctx = ctx->priv;
 272         struct lttng_event *event = lttng_probe_ctx->event;
 273
 274         switch (lttng_chan->header_type) {
 275         case 1: /* compact */
 276                 if (!(ctx->rflags & (RING_BUFFER_RFLAG_FULL_TSC | LTTNG_RFLAG_EXTENDED))) {
 277                         uint32_t id_time = 0;
 278
 279                         bt_bitfield_write(&id_time, uint32_t,
 280                                         0,
 281                                         LTTNG_COMPACT_EVENT_BITS,
 282                                         event_id);
 283                         bt_bitfield_write(&id_time, uint32_t,
 284                                         LTTNG_COMPACT_EVENT_BITS,
 285                                         LTTNG_COMPACT_TSC_BITS, ctx->tsc);
 286                         lib_ring_buffer_write(config, ctx, &id_time, sizeof(id_time));
 287                 } else {
 288                         uint8_t id = 0;
 289                         uint64_t timestamp = ctx->tsc;
 290
 291                         bt_bitfield_write(&id, uint8_t,
 292                                         0,
 293                                         LTTNG_COMPACT_EVENT_BITS,
 294                                         31);
 295                         lib_ring_buffer_write(config, ctx, &id, sizeof(id));
 296                         /* Align extended struct on largest member */
 297                         lib_ring_buffer_align_ctx(ctx, lttng_alignof(uint64_t));
 298                         lib_ring_buffer_write(config, ctx, &event_id, sizeof(event_id));
 299                         lib_ring_buffer_align_ctx(ctx, lttng_alignof(uint64_t));
 300                         lib_ring_buffer_write(config, ctx, &timestamp, sizeof(timestamp));
 301                 }
 302                 break;
 303         case 2: /* large */
 304         {
 305                 if (!(ctx->rflags & (RING_BUFFER_RFLAG_FULL_TSC | LTTNG_RFLAG_EXTENDED))) {
 306                         uint32_t timestamp = (uint32_t) ctx->tsc;
 307                         uint16_t id = event_id;
 308
 309                         lib_ring_buffer_write(config, ctx, &id, sizeof(id));
 310                         lib_ring_buffer_align_ctx(ctx, lttng_alignof(uint32_t));
 311                         lib_ring_buffer_write(config, ctx, &timestamp, sizeof(timestamp));
 312                 } else {
 313                         uint16_t id = 65535;
 314                         uint64_t timestamp = ctx->tsc;
 315
 316                         lib_ring_buffer_write(config, ctx, &id, sizeof(id));
 317                         /* Align extended struct on largest member */
 318                         lib_ring_buffer_align_ctx(ctx, lttng_alignof(uint64_t));
 319                         lib_ring_buffer_write(config, ctx, &event_id, sizeof(event_id));
 320                         lib_ring_buffer_align_ctx(ctx, lttng_alignof(uint64_t));
 321                         lib_ring_buffer_write(config, ctx, &timestamp, sizeof(timestamp));
 322                 }
 323                 break;
 324         }
 325         default:
 326                 WARN_ON_ONCE(1);
 327         }
 328         ctx_record(ctx, lttng_chan, lttng_chan->ctx);
 329         ctx_record(ctx, lttng_chan, event->ctx);
 330         lib_ring_buffer_align_ctx(ctx, ctx->largest_align);
 331 }
 332
 333 static const struct lib_ring_buffer_config client_config;
 334
 335 static u64 client_ring_buffer_clock_read(struct channel *chan)
 336 {
 337         return lib_ring_buffer_clock_read(chan);
 338 }
 339
 340 static
 341 size_t client_record_header_size(const struct lib_ring_buffer_config *config,
 342                                  struct channel *chan, size_t offset,
 343                                  size_t *pre_header_padding,
 344                                  struct lib_ring_buffer_ctx *ctx,
 345                                  void *client_ctx)
 346 {
 347         return record_header_size(config, chan, offset,
 348                                   pre_header_padding, ctx, client_ctx);
 349 }
 350
 351 /**
 352  * client_packet_header_size - called on buffer-switch to a new sub-buffer
 353  *
 354  * Return header size without padding after the structure. Don't use packed
 355  * structure because gcc generates inefficient code on some architectures
 356  * (powerpc, mips..)
 357  */
 358 static size_t client_packet_header_size(void)
 359 {
 360         return offsetof(struct packet_header, ctx.header_end);
 361 }
 362
 363 static void client_buffer_begin(struct lib_ring_buffer *buf, u64 tsc,
 364                                 unsigned int subbuf_idx)
 365 {
 366         struct channel *chan = buf->backend.chan;
 367         struct packet_header *header =
 368                 (struct packet_header *)
 369                         lib_ring_buffer_offset_address(&buf->backend,
 370                                 subbuf_idx * chan->backend.subbuf_size);
 371         struct lttng_event_container *container = channel_get_private(chan);
 372         struct lttng_channel *lttng_chan = lttng_event_container_get_channel(container);
 373         struct lttng_session *session = container->session;
 374
 375         header->magic = CTF_MAGIC_NUMBER;
 376         memcpy(header->uuid, session->uuid.b, sizeof(session->uuid));
 377         header->stream_id = lttng_chan->id;
 378         header->stream_instance_id = buf->backend.cpu;
 379         header->ctx.timestamp_begin = tsc;
 380         header->ctx.timestamp_end = 0;
 381         header->ctx.content_size = ~0ULL; /* for debugging */
 382         header->ctx.packet_size = ~0ULL;
 383         header->ctx.packet_seq_num = chan->backend.num_subbuf * \
 384                                      buf->backend.buf_cnt[subbuf_idx].seq_cnt + \
 385                                      subbuf_idx;
 386         header->ctx.events_discarded = 0;
 387         header->ctx.cpu_id = buf->backend.cpu;
 388 }
 389
 390 /*
 391  * offset is assumed to never be 0 here : never deliver a completely empty
 392  * subbuffer. data_size is between 1 and subbuf_size.
 393  */
 394 static void client_buffer_end(struct lib_ring_buffer *buf, u64 tsc,
 395                               unsigned int subbuf_idx, unsigned long data_size)
 396 {
 397         struct channel *chan = buf->backend.chan;
 398         struct packet_header *header =
 399                 (struct packet_header *)
 400                         lib_ring_buffer_offset_address(&buf->backend,
 401                                 subbuf_idx * chan->backend.subbuf_size);
 402         unsigned long records_lost = 0;
 403
 404         header->ctx.timestamp_end = tsc;
 405         header->ctx.content_size =
 406                 (uint64_t) data_size * CHAR_BIT;                /* in bits */
 407         header->ctx.packet_size =
 408                 (uint64_t) PAGE_ALIGN(data_size) * CHAR_BIT;    /* in bits */
 409         records_lost += lib_ring_buffer_get_records_lost_full(&client_config, buf);
 410         records_lost += lib_ring_buffer_get_records_lost_wrap(&client_config, buf);
 411         records_lost += lib_ring_buffer_get_records_lost_big(&client_config, buf);
 412         header->ctx.events_discarded = records_lost;
 413 }
 414
 415 static int client_buffer_create(struct lib_ring_buffer *buf, void *priv,
 416                                 int cpu, const char *name)
 417 {
 418         return 0;
 419 }
 420
 421 static void client_buffer_finalize(struct lib_ring_buffer *buf, void *priv, int cpu)
 422 {
 423 }
 424
 425 static struct packet_header *client_packet_header(
 426                 const struct lib_ring_buffer_config *config,
 427                 struct lib_ring_buffer *buf)
 428 {
 429         return lib_ring_buffer_read_offset_address(&buf->backend, 0);
 430 }
 431
 432 static int client_timestamp_begin(const struct lib_ring_buffer_config *config,
 433                 struct lib_ring_buffer *buf,
 434                 uint64_t *timestamp_begin)
 435 {
 436         struct packet_header *header = client_packet_header(config, buf);
 437         *timestamp_begin = header->ctx.timestamp_begin;
 438
 439         return 0;
 440 }
 441
 442 static int client_timestamp_end(const struct lib_ring_buffer_config *config,
 443                         struct lib_ring_buffer *buf,
 444                         uint64_t *timestamp_end)
 445 {
 446         struct packet_header *header = client_packet_header(config, buf);
 447         *timestamp_end = header->ctx.timestamp_end;
 448
 449         return 0;
 450 }
 451
 452 static int client_events_discarded(const struct lib_ring_buffer_config *config,
 453                         struct lib_ring_buffer *buf,
 454                         uint64_t *events_discarded)
 455 {
 456         struct packet_header *header = client_packet_header(config, buf);
 457         *events_discarded = header->ctx.events_discarded;
 458
 459         return 0;
 460 }
 461
 462 static int client_content_size(const struct lib_ring_buffer_config *config,
 463                         struct lib_ring_buffer *buf,
 464                         uint64_t *content_size)
 465 {
 466         struct packet_header *header = client_packet_header(config, buf);
 467         *content_size = header->ctx.content_size;
 468
 469         return 0;
 470 }
 471
 472 static int client_packet_size(const struct lib_ring_buffer_config *config,
 473                         struct lib_ring_buffer *buf,
 474                         uint64_t *packet_size)
 475 {
 476         struct packet_header *header = client_packet_header(config, buf);
 477         *packet_size = header->ctx.packet_size;
 478
 479         return 0;
 480 }
 481
 482 static int client_stream_id(const struct lib_ring_buffer_config *config,
 483                         struct lib_ring_buffer *buf,
 484                         uint64_t *stream_id)
 485 {
 486         struct channel *chan = buf->backend.chan;
 487         struct lttng_event_container *container = channel_get_private(chan);
 488         struct lttng_channel *lttng_chan = lttng_event_container_get_channel(container);
 489
 490         *stream_id = lttng_chan->id;
 491         return 0;
 492 }
 493
 494 static int client_current_timestamp(const struct lib_ring_buffer_config *config,
 495                 struct lib_ring_buffer *bufb,
 496                 uint64_t *ts)
 497 {
 498         *ts = config->cb.ring_buffer_clock_read(bufb->backend.chan);
 499
 500         return 0;
 501 }
 502
 503 static int client_sequence_number(const struct lib_ring_buffer_config *config,
 504                         struct lib_ring_buffer *buf,
 505                         uint64_t *seq)
 506 {
 507         struct packet_header *header = client_packet_header(config, buf);
 508
 509         *seq = header->ctx.packet_seq_num;
 510
 511         return 0;
 512 }
 513
 514 static
 515 int client_instance_id(const struct lib_ring_buffer_config *config,
 516                 struct lib_ring_buffer *buf,
 517                 uint64_t *id)
 518 {
 519         *id = buf->backend.cpu;
 520
 521         return 0;
 522 }
 523
 524 static const struct lib_ring_buffer_config client_config = {
 525         .cb.ring_buffer_clock_read = client_ring_buffer_clock_read,
 526         .cb.record_header_size = client_record_header_size,
 527         .cb.subbuffer_header_size = client_packet_header_size,
 528         .cb.buffer_begin = client_buffer_begin,
 529         .cb.buffer_end = client_buffer_end,
 530         .cb.buffer_create = client_buffer_create,
 531         .cb.buffer_finalize = client_buffer_finalize,
 532
 533         .tsc_bits = LTTNG_COMPACT_TSC_BITS,
 534         .alloc = RING_BUFFER_ALLOC_PER_CPU,
 535         .sync = RING_BUFFER_SYNC_PER_CPU,
 536         .mode = RING_BUFFER_MODE_TEMPLATE,
 537         .backend = RING_BUFFER_PAGE,
 538         .output = RING_BUFFER_OUTPUT_TEMPLATE,
 539         .oops = RING_BUFFER_OOPS_CONSISTENCY,
 540         .ipi = RING_BUFFER_IPI_BARRIER,
 541         .wakeup = RING_BUFFER_WAKEUP_BY_TIMER,
 542 };
 543
 544 static
 545 void release_priv_ops(void *priv_ops)
 546 {
 547         module_put(THIS_MODULE);
 548 }
 549
 550 static
 551 void lttng_channel_destroy(struct channel *chan)
 552 {
 553         channel_destroy(chan);
 554 }
 555
 556 static
 557 struct channel *_channel_create(const char *name,
 558                                 void *priv, void *buf_addr,
 559                                 size_t subbuf_size, size_t num_subbuf,
 560                                 unsigned int switch_timer_interval,
 561                                 unsigned int read_timer_interval)
 562 {
 563         struct lttng_event_container *container = priv;
 564         struct channel *chan;
 565
 566         chan = channel_create(&client_config, name, container, buf_addr,
 567                               subbuf_size, num_subbuf, switch_timer_interval,
 568                               read_timer_interval);
 569         if (chan) {
 570                 /*
 571                  * Ensure this module is not unloaded before we finish
 572                  * using lttng_relay_transport.ops.
 573                  */
 574                 if (!try_module_get(THIS_MODULE)) {
 575                         printk(KERN_WARNING "LTTng: Can't lock transport module.\n");
 576                         goto error;
 577                 }
 578                 chan->backend.priv_ops = &lttng_relay_transport.ops;
 579                 chan->backend.release_priv_ops = release_priv_ops;
 580         }
 581         return chan;
 582
 583 error:
 584         lttng_channel_destroy(chan);
 585         return NULL;
 586 }
 587
 588 static
 589 struct lib_ring_buffer *lttng_buffer_read_open(struct channel *chan)
 590 {
 591         struct lib_ring_buffer *buf;
 592         int cpu;
 593
 594         for_each_channel_cpu(cpu, chan) {
 595                 buf = channel_get_ring_buffer(&client_config, chan, cpu);
 596                 if (!lib_ring_buffer_open_read(buf))
 597                         return buf;
 598         }
 599         return NULL;
 600 }
 601
 602 static
 603 int lttng_buffer_has_read_closed_stream(struct channel *chan)
 604 {
 605         struct lib_ring_buffer *buf;
 606         int cpu;
 607
 608         for_each_channel_cpu(cpu, chan) {
 609                 buf = channel_get_ring_buffer(&client_config, chan, cpu);
 610                 if (!atomic_long_read(&buf->active_readers))
 611                         return 1;
 612         }
 613         return 0;
 614 }
 615
 616 static
 617 void lttng_buffer_read_close(struct lib_ring_buffer *buf)
 618 {
 619         lib_ring_buffer_release_read(buf);
 620 }
 621
 622 static
 623 int lttng_event_reserve(struct lib_ring_buffer_ctx *ctx,
 624                       uint32_t event_id)
 625 {
 626         struct lttng_event_container *container = channel_get_private(ctx->chan);
 627         struct lttng_channel *lttng_chan = lttng_event_container_get_channel(container);
 628         struct lttng_probe_ctx *lttng_probe_ctx = ctx->priv;
 629         struct lttng_event *event = lttng_probe_ctx->event;
 630         struct lttng_client_ctx client_ctx;
 631         int ret, cpu;
 632
 633         cpu = lib_ring_buffer_get_cpu(&client_config);
 634         if (unlikely(cpu < 0))
 635                 return -EPERM;
 636         ctx->cpu = cpu;
 637
 638         /* Compute internal size of context structures. */
 639         ctx_get_struct_size(lttng_chan->ctx, &client_ctx.packet_context_len, lttng_chan, ctx);
 640         ctx_get_struct_size(event->ctx, &client_ctx.event_context_len, lttng_chan, ctx);
 641
 642         switch (lttng_chan->header_type) {
 643         case 1: /* compact */
 644                 if (event_id > 30)
 645                         ctx->rflags |= LTTNG_RFLAG_EXTENDED;
 646                 break;
 647         case 2: /* large */
 648                 if (event_id > 65534)
 649                         ctx->rflags |= LTTNG_RFLAG_EXTENDED;
 650                 break;
 651         default:
 652                 WARN_ON_ONCE(1);
 653         }
 654
 655         ret = lib_ring_buffer_reserve(&client_config, ctx, &client_ctx);
 656         if (unlikely(ret))
 657                 goto put;
 658         lib_ring_buffer_backend_get_pages(&client_config, ctx,
 659                         &ctx->backend_pages);
 660         lttng_write_event_header(&client_config, ctx, event_id);
 661         return 0;
 662 put:
 663         lib_ring_buffer_put_cpu(&client_config);
 664         return ret;
 665 }
 666
 667 static
 668 void lttng_event_commit(struct lib_ring_buffer_ctx *ctx)
 669 {
 670         lib_ring_buffer_commit(&client_config, ctx);
 671         lib_ring_buffer_put_cpu(&client_config);
 672 }
 673
 674 static
 675 void lttng_event_write(struct lib_ring_buffer_ctx *ctx, const void *src,
 676                      size_t len)
 677 {
 678         lib_ring_buffer_write(&client_config, ctx, src, len);
 679 }
 680
 681 static
 682 void lttng_event_write_from_user(struct lib_ring_buffer_ctx *ctx,
 683                                const void __user *src, size_t len)
 684 {
 685         lib_ring_buffer_copy_from_user_inatomic(&client_config, ctx, src, len);
 686 }
 687
 688 static
 689 void lttng_event_memset(struct lib_ring_buffer_ctx *ctx,
 690                 int c, size_t len)
 691 {
 692         lib_ring_buffer_memset(&client_config, ctx, c, len);
 693 }
 694
 695 static
 696 void lttng_event_strcpy(struct lib_ring_buffer_ctx *ctx, const char *src,
 697                 size_t len)
 698 {
 699         lib_ring_buffer_strcpy(&client_config, ctx, src, len, '#');
 700 }
 701
 702 static
 703 void lttng_event_strcpy_from_user(struct lib_ring_buffer_ctx *ctx,
 704                 const char __user *src, size_t len)
 705 {
 706         lib_ring_buffer_strcpy_from_user_inatomic(&client_config, ctx, src,
 707                         len, '#');
 708 }
 709
 710 static
 711 wait_queue_head_t *lttng_get_writer_buf_wait_queue(struct channel *chan, int cpu)
 712 {
 713         struct lib_ring_buffer *buf = channel_get_ring_buffer(&client_config,
 714                                         chan, cpu);
 715         return &buf->write_wait;
 716 }
 717
 718 static
 719 wait_queue_head_t *lttng_get_hp_wait_queue(struct channel *chan)
 720 {
 721         return &chan->hp_wait;
 722 }
 723
 724 static
 725 int lttng_is_finalized(struct channel *chan)
 726 {
 727         return lib_ring_buffer_channel_is_finalized(chan);
 728 }
 729
 730 static
 731 int lttng_is_disabled(struct channel *chan)
 732 {
 733         return lib_ring_buffer_channel_is_disabled(chan);
 734 }
 735
 736 static struct lttng_transport lttng_relay_transport = {
 737         .name = "relay-" RING_BUFFER_MODE_TEMPLATE_STRING,
 738         .owner = THIS_MODULE,
 739         .ops = {
 740                 .channel_create = _channel_create,
 741                 .channel_destroy = lttng_channel_destroy,
 742                 .buffer_read_open = lttng_buffer_read_open,
 743                 .buffer_has_read_closed_stream =
 744                         lttng_buffer_has_read_closed_stream,
 745                 .buffer_read_close = lttng_buffer_read_close,
 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                 .packet_avail_size = NULL,      /* Would be racy anyway */
 754                 .get_writer_buf_wait_queue = lttng_get_writer_buf_wait_queue,
 755                 .get_hp_wait_queue = lttng_get_hp_wait_queue,
 756                 .is_finalized = lttng_is_finalized,
 757                 .is_disabled = lttng_is_disabled,
 758                 .timestamp_begin = client_timestamp_begin,
 759                 .timestamp_end = client_timestamp_end,
 760                 .events_discarded = client_events_discarded,
 761                 .content_size = client_content_size,
 762                 .packet_size = client_packet_size,
 763                 .stream_id = client_stream_id,
 764                 .current_timestamp = client_current_timestamp,
 765                 .sequence_number = client_sequence_number,
 766                 .instance_id = client_instance_id,
 767         },
 768 };
 769
 770 static int __init lttng_ring_buffer_client_init(void)
 771 {
 772         /*
 773          * This vmalloc sync all also takes care of the lib ring buffer
 774          * vmalloc'd module pages when it is built as a module into LTTng.
 775          */
 776         wrapper_vmalloc_sync_mappings();
 777         lttng_transport_register(&lttng_relay_transport);
 778         return 0;
 779 }
 780
 781 module_init(lttng_ring_buffer_client_init);
 782
 783 static void __exit lttng_ring_buffer_client_exit(void)
 784 {
 785         lttng_transport_unregister(&lttng_relay_transport);
 786 }
 787
 788 module_exit(lttng_ring_buffer_client_exit);
 789
 790 MODULE_LICENSE("GPL and additional rights");
 791 MODULE_AUTHOR("Mathieu Desnoyers <mathieu.desnoyers@efficios.com>");
 792 MODULE_DESCRIPTION("LTTng ring buffer " RING_BUFFER_MODE_TEMPLATE_STRING
 793                    " client");
 794 MODULE_VERSION(__stringify(LTTNG_MODULES_MAJOR_VERSION) "."
 795         __stringify(LTTNG_MODULES_MINOR_VERSION) "."
 796         __stringify(LTTNG_MODULES_PATCHLEVEL_VERSION)
 797         LTTNG_MODULES_EXTRAVERSION);