lttng-ring-buffer-client.h

   1 /*
   2  * lttng-ring-buffer-client.h
   3  *
   4  * LTTng lib ring buffer client template.
   5  *
   6  * Copyright (C) 2010-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   7  *
   8  * This library is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU Lesser General Public
  10  * License as published by the Free Software Foundation; only
  11  * version 2.1 of the License.
  12  *
  13  * This library is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  16  * Lesser General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU Lesser General Public
  19  * License along with this library; if not, write to the Free Software
  20  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  21  */
  22
  23 #include <linux/module.h>
  24 #include <linux/types.h>
  25 #include "lib/bitfield.h"
  26 #include "wrapper/vmalloc.h"    /* for wrapper_vmalloc_sync_all() */
  27 #include "wrapper/trace-clock.h"
  28 #include "lttng-events.h"
  29 #include "lttng-tracer.h"
  30 #include "wrapper/ringbuffer/frontend_types.h"
  31
  32 #define LTTNG_COMPACT_EVENT_BITS        5
  33 #define LTTNG_COMPACT_TSC_BITS          27
  34
  35 static struct lttng_transport lttng_relay_transport;
  36
  37 /*
  38  * Keep the natural field alignment for _each field_ within this structure if
  39  * you ever add/remove a field from this header. Packed attribute is not used
  40  * because gcc generates poor code on at least powerpc and mips. Don't ever
  41  * let gcc add padding between the structure elements.
  42  *
  43  * The guarantee we have with timestamps is that all the events in a
  44  * packet are included (inclusive) within the begin/end timestamps of
  45  * the packet. Another guarantee we have is that the "timestamp begin",
  46  * as well as the event timestamps, are monotonically increasing (never
  47  * decrease) when moving forward in a stream (physically). But this
  48  * guarantee does not apply to "timestamp end", because it is sampled at
  49  * commit time, which is not ordered with respect to space reservation.
  50  */
  51
  52 struct packet_header {
  53         /* Trace packet header */
  54         uint32_t magic;                 /*
  55                                          * Trace magic number.
  56                                          * contains endianness information.
  57                                          */
  58         uint8_t uuid[16];
  59         uint32_t stream_id;
  60         uint64_t stream_instance_id;
  61
  62         struct {
  63                 /* Stream packet context */
  64                 uint64_t timestamp_begin;       /* Cycle count at subbuffer start */
  65                 uint64_t timestamp_end;         /* Cycle count at subbuffer end */
  66                 uint64_t content_size;          /* Size of data in subbuffer */
  67                 uint64_t packet_size;           /* Subbuffer size (include padding) */
  68                 uint64_t packet_seq_num;        /* Packet sequence number */
  69                 unsigned long events_discarded; /*
  70                                                  * Events lost in this subbuffer since
  71                                                  * the beginning of the trace.
  72                                                  * (may overflow)
  73                                                  */
  74                 uint32_t cpu_id;                /* CPU id associated with stream */
  75                 uint8_t header_end;             /* End of header */
  76         } ctx;
  77 };
  78
  79
  80 static inline notrace u64 lib_ring_buffer_clock_read(struct channel *chan)
  81 {
  82         return trace_clock_read64();
  83 }
  84
  85 static inline
  86 size_t ctx_get_size(size_t offset, struct lttng_ctx *ctx)
  87 {
  88         int i;
  89         size_t orig_offset = offset;
  90
  91         if (likely(!ctx))
  92                 return 0;
  93         offset += lib_ring_buffer_align(offset, ctx->largest_align);
  94         for (i = 0; i < ctx->nr_fields; i++)
  95                 offset += ctx->fields[i].get_size(offset);
  96         return offset - orig_offset;
  97 }
  98
  99 static inline
 100 void ctx_record(struct lib_ring_buffer_ctx *bufctx,
 101                 struct lttng_channel *chan,
 102                 struct lttng_ctx *ctx)
 103 {
 104         int i;
 105
 106         if (likely(!ctx))
 107                 return;
 108         lib_ring_buffer_align_ctx(bufctx, ctx->largest_align);
 109         for (i = 0; i < ctx->nr_fields; i++)
 110                 ctx->fields[i].record(&ctx->fields[i], bufctx, chan);
 111 }
 112
 113 /*
 114  * record_header_size - Calculate the header size and padding necessary.
 115  * @config: ring buffer instance configuration
 116  * @chan: channel
 117  * @offset: offset in the write buffer
 118  * @pre_header_padding: padding to add before the header (output)
 119  * @ctx: reservation context
 120  *
 121  * Returns the event header size (including padding).
 122  *
 123  * The payload must itself determine its own alignment from the biggest type it
 124  * contains.
 125  */
 126 static __inline__
 127 size_t record_header_size(const struct lib_ring_buffer_config *config,
 128                                  struct channel *chan, size_t offset,
 129                                  size_t *pre_header_padding,
 130                                  struct lib_ring_buffer_ctx *ctx)
 131 {
 132         struct lttng_channel *lttng_chan = channel_get_private(chan);
 133         struct lttng_event *event = ctx->priv;
 134         size_t orig_offset = offset;
 135         size_t padding;
 136
 137         switch (lttng_chan->header_type) {
 138         case 1: /* compact */
 139                 padding = lib_ring_buffer_align(offset, lttng_alignof(uint32_t));
 140                 offset += padding;
 141                 if (!(ctx->rflags & (RING_BUFFER_RFLAG_FULL_TSC | LTTNG_RFLAG_EXTENDED))) {
 142                         offset += sizeof(uint32_t);     /* id and timestamp */
 143                 } else {
 144                         /* Minimum space taken by LTTNG_COMPACT_EVENT_BITS id */
 145                         offset += (LTTNG_COMPACT_EVENT_BITS + CHAR_BIT - 1) / CHAR_BIT;
 146                         /* Align extended struct on largest member */
 147                         offset += lib_ring_buffer_align(offset, lttng_alignof(uint64_t));
 148                         offset += sizeof(uint32_t);     /* id */
 149                         offset += lib_ring_buffer_align(offset, lttng_alignof(uint64_t));
 150                         offset += sizeof(uint64_t);     /* timestamp */
 151                 }
 152                 break;
 153         case 2: /* large */
 154                 padding = lib_ring_buffer_align(offset, lttng_alignof(uint16_t));
 155                 offset += padding;
 156                 offset += sizeof(uint16_t);
 157                 if (!(ctx->rflags & (RING_BUFFER_RFLAG_FULL_TSC | LTTNG_RFLAG_EXTENDED))) {
 158                         offset += lib_ring_buffer_align(offset, lttng_alignof(uint32_t));
 159                         offset += sizeof(uint32_t);     /* timestamp */
 160                 } else {
 161                         /* Align extended struct on largest member */
 162                         offset += lib_ring_buffer_align(offset, lttng_alignof(uint64_t));
 163                         offset += sizeof(uint32_t);     /* id */
 164                         offset += lib_ring_buffer_align(offset, lttng_alignof(uint64_t));
 165                         offset += sizeof(uint64_t);     /* timestamp */
 166                 }
 167                 break;
 168         default:
 169                 padding = 0;
 170                 WARN_ON_ONCE(1);
 171         }
 172         offset += ctx_get_size(offset, event->ctx);
 173         offset += ctx_get_size(offset, lttng_chan->ctx);
 174
 175         *pre_header_padding = padding;
 176         return offset - orig_offset;
 177 }
 178
 179 #include "wrapper/ringbuffer/api.h"
 180
 181 static
 182 void lttng_write_event_header_slow(const struct lib_ring_buffer_config *config,
 183                                  struct lib_ring_buffer_ctx *ctx,
 184                                  uint32_t event_id);
 185
 186 /*
 187  * lttng_write_event_header
 188  *
 189  * Writes the event header to the offset (already aligned on 32-bits).
 190  *
 191  * @config: ring buffer instance configuration
 192  * @ctx: reservation context
 193  * @event_id: event ID
 194  */
 195 static __inline__
 196 void lttng_write_event_header(const struct lib_ring_buffer_config *config,
 197                             struct lib_ring_buffer_ctx *ctx,
 198                             uint32_t event_id)
 199 {
 200         struct lttng_channel *lttng_chan = channel_get_private(ctx->chan);
 201         struct lttng_event *event = ctx->priv;
 202
 203         if (unlikely(ctx->rflags))
 204                 goto slow_path;
 205
 206         switch (lttng_chan->header_type) {
 207         case 1: /* compact */
 208         {
 209                 uint32_t id_time = 0;
 210
 211                 bt_bitfield_write(&id_time, uint32_t,
 212                                 0,
 213                                 LTTNG_COMPACT_EVENT_BITS,
 214                                 event_id);
 215                 bt_bitfield_write(&id_time, uint32_t,
 216                                 LTTNG_COMPACT_EVENT_BITS,
 217                                 LTTNG_COMPACT_TSC_BITS,
 218                                 ctx->tsc);
 219                 lib_ring_buffer_write(config, ctx, &id_time, sizeof(id_time));
 220                 break;
 221         }
 222         case 2: /* large */
 223         {
 224                 uint32_t timestamp = (uint32_t) ctx->tsc;
 225                 uint16_t id = event_id;
 226
 227                 lib_ring_buffer_write(config, ctx, &id, sizeof(id));
 228                 lib_ring_buffer_align_ctx(ctx, lttng_alignof(uint32_t));
 229                 lib_ring_buffer_write(config, ctx, &timestamp, sizeof(timestamp));
 230                 break;
 231         }
 232         default:
 233                 WARN_ON_ONCE(1);
 234         }
 235
 236         ctx_record(ctx, lttng_chan, lttng_chan->ctx);
 237         ctx_record(ctx, lttng_chan, event->ctx);
 238         lib_ring_buffer_align_ctx(ctx, ctx->largest_align);
 239
 240         return;
 241
 242 slow_path:
 243         lttng_write_event_header_slow(config, ctx, event_id);
 244 }
 245
 246 static
 247 void lttng_write_event_header_slow(const struct lib_ring_buffer_config *config,
 248                                  struct lib_ring_buffer_ctx *ctx,
 249                                  uint32_t event_id)
 250 {
 251         struct lttng_channel *lttng_chan = channel_get_private(ctx->chan);
 252         struct lttng_event *event = ctx->priv;
 253
 254         switch (lttng_chan->header_type) {
 255         case 1: /* compact */
 256                 if (!(ctx->rflags & (RING_BUFFER_RFLAG_FULL_TSC | LTTNG_RFLAG_EXTENDED))) {
 257                         uint32_t id_time = 0;
 258
 259                         bt_bitfield_write(&id_time, uint32_t,
 260                                         0,
 261                                         LTTNG_COMPACT_EVENT_BITS,
 262                                         event_id);
 263                         bt_bitfield_write(&id_time, uint32_t,
 264                                         LTTNG_COMPACT_EVENT_BITS,
 265                                         LTTNG_COMPACT_TSC_BITS, ctx->tsc);
 266                         lib_ring_buffer_write(config, ctx, &id_time, sizeof(id_time));
 267                 } else {
 268                         uint8_t id = 0;
 269                         uint64_t timestamp = ctx->tsc;
 270
 271                         bt_bitfield_write(&id, uint8_t,
 272                                         0,
 273                                         LTTNG_COMPACT_EVENT_BITS,
 274                                         31);
 275                         lib_ring_buffer_write(config, ctx, &id, sizeof(id));
 276                         /* Align extended struct on largest member */
 277                         lib_ring_buffer_align_ctx(ctx, lttng_alignof(uint64_t));
 278                         lib_ring_buffer_write(config, ctx, &event_id, sizeof(event_id));
 279                         lib_ring_buffer_align_ctx(ctx, lttng_alignof(uint64_t));
 280                         lib_ring_buffer_write(config, ctx, &timestamp, sizeof(timestamp));
 281                 }
 282                 break;
 283         case 2: /* large */
 284         {
 285                 if (!(ctx->rflags & (RING_BUFFER_RFLAG_FULL_TSC | LTTNG_RFLAG_EXTENDED))) {
 286                         uint32_t timestamp = (uint32_t) ctx->tsc;
 287                         uint16_t id = event_id;
 288
 289                         lib_ring_buffer_write(config, ctx, &id, sizeof(id));
 290                         lib_ring_buffer_align_ctx(ctx, lttng_alignof(uint32_t));
 291                         lib_ring_buffer_write(config, ctx, &timestamp, sizeof(timestamp));
 292                 } else {
 293                         uint16_t id = 65535;
 294                         uint64_t timestamp = ctx->tsc;
 295
 296                         lib_ring_buffer_write(config, ctx, &id, sizeof(id));
 297                         /* Align extended struct on largest member */
 298                         lib_ring_buffer_align_ctx(ctx, lttng_alignof(uint64_t));
 299                         lib_ring_buffer_write(config, ctx, &event_id, sizeof(event_id));
 300                         lib_ring_buffer_align_ctx(ctx, lttng_alignof(uint64_t));
 301                         lib_ring_buffer_write(config, ctx, &timestamp, sizeof(timestamp));
 302                 }
 303                 break;
 304         }
 305         default:
 306                 WARN_ON_ONCE(1);
 307         }
 308         ctx_record(ctx, lttng_chan, lttng_chan->ctx);
 309         ctx_record(ctx, lttng_chan, event->ctx);
 310         lib_ring_buffer_align_ctx(ctx, ctx->largest_align);
 311 }
 312
 313 static const struct lib_ring_buffer_config client_config;
 314
 315 static u64 client_ring_buffer_clock_read(struct channel *chan)
 316 {
 317         return lib_ring_buffer_clock_read(chan);
 318 }
 319
 320 static
 321 size_t client_record_header_size(const struct lib_ring_buffer_config *config,
 322                                  struct channel *chan, size_t offset,
 323                                  size_t *pre_header_padding,
 324                                  struct lib_ring_buffer_ctx *ctx)
 325 {
 326         return record_header_size(config, chan, offset,
 327                                   pre_header_padding, ctx);
 328 }
 329
 330 /**
 331  * client_packet_header_size - called on buffer-switch to a new sub-buffer
 332  *
 333  * Return header size without padding after the structure. Don't use packed
 334  * structure because gcc generates inefficient code on some architectures
 335  * (powerpc, mips..)
 336  */
 337 static size_t client_packet_header_size(void)
 338 {
 339         return offsetof(struct packet_header, ctx.header_end);
 340 }
 341
 342 static void client_buffer_begin(struct lib_ring_buffer *buf, u64 tsc,
 343                                 unsigned int subbuf_idx)
 344 {
 345         struct channel *chan = buf->backend.chan;
 346         struct packet_header *header =
 347                 (struct packet_header *)
 348                         lib_ring_buffer_offset_address(&buf->backend,
 349                                 subbuf_idx * chan->backend.subbuf_size);
 350         struct lttng_channel *lttng_chan = channel_get_private(chan);
 351         struct lttng_session *session = lttng_chan->session;
 352
 353         header->magic = CTF_MAGIC_NUMBER;
 354         memcpy(header->uuid, session->uuid.b, sizeof(session->uuid));
 355         header->stream_id = lttng_chan->id;
 356         header->stream_instance_id = buf->backend.cpu;
 357         header->ctx.timestamp_begin = tsc;
 358         header->ctx.timestamp_end = 0;
 359         header->ctx.content_size = ~0ULL; /* for debugging */
 360         header->ctx.packet_size = ~0ULL;
 361         header->ctx.packet_seq_num = chan->backend.num_subbuf * \
 362                                      buf->backend.buf_cnt[subbuf_idx].seq_cnt + \
 363                                      subbuf_idx;
 364         header->ctx.events_discarded = 0;
 365         header->ctx.cpu_id = buf->backend.cpu;
 366 }
 367
 368 /*
 369  * offset is assumed to never be 0 here : never deliver a completely empty
 370  * subbuffer. data_size is between 1 and subbuf_size.
 371  */
 372 static void client_buffer_end(struct lib_ring_buffer *buf, u64 tsc,
 373                               unsigned int subbuf_idx, unsigned long data_size)
 374 {
 375         struct channel *chan = buf->backend.chan;
 376         struct packet_header *header =
 377                 (struct packet_header *)
 378                         lib_ring_buffer_offset_address(&buf->backend,
 379                                 subbuf_idx * chan->backend.subbuf_size);
 380         unsigned long records_lost = 0;
 381
 382         header->ctx.timestamp_end = tsc;
 383         header->ctx.content_size =
 384                 (uint64_t) data_size * CHAR_BIT;                /* in bits */
 385         header->ctx.packet_size =
 386                 (uint64_t) PAGE_ALIGN(data_size) * CHAR_BIT;    /* in bits */
 387         records_lost += lib_ring_buffer_get_records_lost_full(&client_config, buf);
 388         records_lost += lib_ring_buffer_get_records_lost_wrap(&client_config, buf);
 389         records_lost += lib_ring_buffer_get_records_lost_big(&client_config, buf);
 390         header->ctx.events_discarded = records_lost;
 391 }
 392
 393 static int client_buffer_create(struct lib_ring_buffer *buf, void *priv,
 394                                 int cpu, const char *name)
 395 {
 396         return 0;
 397 }
 398
 399 static void client_buffer_finalize(struct lib_ring_buffer *buf, void *priv, int cpu)
 400 {
 401 }
 402
 403 static struct packet_header *client_packet_header(
 404                 const struct lib_ring_buffer_config *config,
 405                 struct lib_ring_buffer *buf)
 406 {
 407         return lib_ring_buffer_read_offset_address(&buf->backend, 0);
 408 }
 409
 410 static int client_timestamp_begin(const struct lib_ring_buffer_config *config,
 411                 struct lib_ring_buffer *buf,
 412                 uint64_t *timestamp_begin)
 413 {
 414         struct packet_header *header = client_packet_header(config, buf);
 415         *timestamp_begin = header->ctx.timestamp_begin;
 416
 417         return 0;
 418 }
 419
 420 static int client_timestamp_end(const struct lib_ring_buffer_config *config,
 421                         struct lib_ring_buffer *buf,
 422                         uint64_t *timestamp_end)
 423 {
 424         struct packet_header *header = client_packet_header(config, buf);
 425         *timestamp_end = header->ctx.timestamp_end;
 426
 427         return 0;
 428 }
 429
 430 static int client_events_discarded(const struct lib_ring_buffer_config *config,
 431                         struct lib_ring_buffer *buf,
 432                         uint64_t *events_discarded)
 433 {
 434         struct packet_header *header = client_packet_header(config, buf);
 435         *events_discarded = header->ctx.events_discarded;
 436
 437         return 0;
 438 }
 439
 440 static int client_content_size(const struct lib_ring_buffer_config *config,
 441                         struct lib_ring_buffer *buf,
 442                         uint64_t *content_size)
 443 {
 444         struct packet_header *header = client_packet_header(config, buf);
 445         *content_size = header->ctx.content_size;
 446
 447         return 0;
 448 }
 449
 450 static int client_packet_size(const struct lib_ring_buffer_config *config,
 451                         struct lib_ring_buffer *buf,
 452                         uint64_t *packet_size)
 453 {
 454         struct packet_header *header = client_packet_header(config, buf);
 455         *packet_size = header->ctx.packet_size;
 456
 457         return 0;
 458 }
 459
 460 static int client_stream_id(const struct lib_ring_buffer_config *config,
 461                         struct lib_ring_buffer *buf,
 462                         uint64_t *stream_id)
 463 {
 464         struct packet_header *header = client_packet_header(config, buf);
 465         *stream_id = header->stream_id;
 466
 467         return 0;
 468 }
 469
 470 static int client_current_timestamp(const struct lib_ring_buffer_config *config,
 471                 struct lib_ring_buffer *bufb,
 472                 uint64_t *ts)
 473 {
 474         *ts = config->cb.ring_buffer_clock_read(bufb->backend.chan);
 475
 476         return 0;
 477 }
 478
 479 static int client_sequence_number(const struct lib_ring_buffer_config *config,
 480                         struct lib_ring_buffer *buf,
 481                         uint64_t *seq)
 482 {
 483         struct packet_header *header = client_packet_header(config, buf);
 484
 485         *seq = header->ctx.packet_seq_num;
 486
 487         return 0;
 488 }
 489
 490 static
 491 int client_instance_id(const struct lib_ring_buffer_config *config,
 492                 struct lib_ring_buffer *buf,
 493                 uint64_t *id)
 494 {
 495         struct packet_header *header = client_packet_header(config, buf);
 496         *id = header->stream_instance_id;
 497
 498         return 0;
 499 }
 500
 501 static const struct lib_ring_buffer_config client_config = {
 502         .cb.ring_buffer_clock_read = client_ring_buffer_clock_read,
 503         .cb.record_header_size = client_record_header_size,
 504         .cb.subbuffer_header_size = client_packet_header_size,
 505         .cb.buffer_begin = client_buffer_begin,
 506         .cb.buffer_end = client_buffer_end,
 507         .cb.buffer_create = client_buffer_create,
 508         .cb.buffer_finalize = client_buffer_finalize,
 509
 510         .tsc_bits = LTTNG_COMPACT_TSC_BITS,
 511         .alloc = RING_BUFFER_ALLOC_PER_CPU,
 512         .sync = RING_BUFFER_SYNC_PER_CPU,
 513         .mode = RING_BUFFER_MODE_TEMPLATE,
 514         .backend = RING_BUFFER_PAGE,
 515         .output = RING_BUFFER_OUTPUT_TEMPLATE,
 516         .oops = RING_BUFFER_OOPS_CONSISTENCY,
 517         .ipi = RING_BUFFER_IPI_BARRIER,
 518         .wakeup = RING_BUFFER_WAKEUP_BY_TIMER,
 519 };
 520
 521 static
 522 void release_priv_ops(void *priv_ops)
 523 {
 524         module_put(THIS_MODULE);
 525 }
 526
 527 static
 528 void lttng_channel_destroy(struct channel *chan)
 529 {
 530         channel_destroy(chan);
 531 }
 532
 533 static
 534 struct channel *_channel_create(const char *name,
 535                                 struct lttng_channel *lttng_chan, void *buf_addr,
 536                                 size_t subbuf_size, size_t num_subbuf,
 537                                 unsigned int switch_timer_interval,
 538                                 unsigned int read_timer_interval)
 539 {
 540         struct channel *chan;
 541
 542         chan = channel_create(&client_config, name, lttng_chan, buf_addr,
 543                               subbuf_size, num_subbuf, switch_timer_interval,
 544                               read_timer_interval);
 545         if (chan) {
 546                 /*
 547                  * Ensure this module is not unloaded before we finish
 548                  * using lttng_relay_transport.ops.
 549                  */
 550                 if (!try_module_get(THIS_MODULE)) {
 551                         printk(KERN_WARNING "LTT : Can't lock transport module.\n");
 552                         goto error;
 553                 }
 554                 chan->backend.priv_ops = &lttng_relay_transport.ops;
 555                 chan->backend.release_priv_ops = release_priv_ops;
 556         }
 557         return chan;
 558
 559 error:
 560         lttng_channel_destroy(chan);
 561         return NULL;
 562 }
 563
 564 static
 565 struct lib_ring_buffer *lttng_buffer_read_open(struct channel *chan)
 566 {
 567         struct lib_ring_buffer *buf;
 568         int cpu;
 569
 570         for_each_channel_cpu(cpu, chan) {
 571                 buf = channel_get_ring_buffer(&client_config, chan, cpu);
 572                 if (!lib_ring_buffer_open_read(buf))
 573                         return buf;
 574         }
 575         return NULL;
 576 }
 577
 578 static
 579 int lttng_buffer_has_read_closed_stream(struct channel *chan)
 580 {
 581         struct lib_ring_buffer *buf;
 582         int cpu;
 583
 584         for_each_channel_cpu(cpu, chan) {
 585                 buf = channel_get_ring_buffer(&client_config, chan, cpu);
 586                 if (!atomic_long_read(&buf->active_readers))
 587                         return 1;
 588         }
 589         return 0;
 590 }
 591
 592 static
 593 void lttng_buffer_read_close(struct lib_ring_buffer *buf)
 594 {
 595         lib_ring_buffer_release_read(buf);
 596 }
 597
 598 static
 599 int lttng_event_reserve(struct lib_ring_buffer_ctx *ctx,
 600                       uint32_t event_id)
 601 {
 602         struct lttng_channel *lttng_chan = channel_get_private(ctx->chan);
 603         int ret, cpu;
 604
 605         cpu = lib_ring_buffer_get_cpu(&client_config);
 606         if (cpu < 0)
 607                 return -EPERM;
 608         ctx->cpu = cpu;
 609
 610         switch (lttng_chan->header_type) {
 611         case 1: /* compact */
 612                 if (event_id > 30)
 613                         ctx->rflags |= LTTNG_RFLAG_EXTENDED;
 614                 break;
 615         case 2: /* large */
 616                 if (event_id > 65534)
 617                         ctx->rflags |= LTTNG_RFLAG_EXTENDED;
 618                 break;
 619         default:
 620                 WARN_ON_ONCE(1);
 621         }
 622
 623         ret = lib_ring_buffer_reserve(&client_config, ctx);
 624         if (ret)
 625                 goto put;
 626         lttng_write_event_header(&client_config, ctx, event_id);
 627         return 0;
 628 put:
 629         lib_ring_buffer_put_cpu(&client_config);
 630         return ret;
 631 }
 632
 633 static
 634 void lttng_event_commit(struct lib_ring_buffer_ctx *ctx)
 635 {
 636         lib_ring_buffer_commit(&client_config, ctx);
 637         lib_ring_buffer_put_cpu(&client_config);
 638 }
 639
 640 static
 641 void lttng_event_write(struct lib_ring_buffer_ctx *ctx, const void *src,
 642                      size_t len)
 643 {
 644         lib_ring_buffer_write(&client_config, ctx, src, len);
 645 }
 646
 647 static
 648 void lttng_event_write_from_user(struct lib_ring_buffer_ctx *ctx,
 649                                const void __user *src, size_t len)
 650 {
 651         lib_ring_buffer_copy_from_user_inatomic(&client_config, ctx, src, len);
 652 }
 653
 654 static
 655 void lttng_event_memset(struct lib_ring_buffer_ctx *ctx,
 656                 int c, size_t len)
 657 {
 658         lib_ring_buffer_memset(&client_config, ctx, c, len);
 659 }
 660
 661 static
 662 void lttng_event_strcpy(struct lib_ring_buffer_ctx *ctx, const char *src,
 663                 size_t len)
 664 {
 665         lib_ring_buffer_strcpy(&client_config, ctx, src, len, '#');
 666 }
 667
 668 static
 669 void lttng_event_strcpy_from_user(struct lib_ring_buffer_ctx *ctx,
 670                 const char __user *src, size_t len)
 671 {
 672         lib_ring_buffer_strcpy_from_user_inatomic(&client_config, ctx, src,
 673                         len, '#');
 674 }
 675
 676 static
 677 wait_queue_head_t *lttng_get_writer_buf_wait_queue(struct channel *chan, int cpu)
 678 {
 679         struct lib_ring_buffer *buf = channel_get_ring_buffer(&client_config,
 680                                         chan, cpu);
 681         return &buf->write_wait;
 682 }
 683
 684 static
 685 wait_queue_head_t *lttng_get_hp_wait_queue(struct channel *chan)
 686 {
 687         return &chan->hp_wait;
 688 }
 689
 690 static
 691 int lttng_is_finalized(struct channel *chan)
 692 {
 693         return lib_ring_buffer_channel_is_finalized(chan);
 694 }
 695
 696 static
 697 int lttng_is_disabled(struct channel *chan)
 698 {
 699         return lib_ring_buffer_channel_is_disabled(chan);
 700 }
 701
 702 static struct lttng_transport lttng_relay_transport = {
 703         .name = "relay-" RING_BUFFER_MODE_TEMPLATE_STRING,
 704         .owner = THIS_MODULE,
 705         .ops = {
 706                 .channel_create = _channel_create,
 707                 .channel_destroy = lttng_channel_destroy,
 708                 .buffer_read_open = lttng_buffer_read_open,
 709                 .buffer_has_read_closed_stream =
 710                         lttng_buffer_has_read_closed_stream,
 711                 .buffer_read_close = lttng_buffer_read_close,
 712                 .event_reserve = lttng_event_reserve,
 713                 .event_commit = lttng_event_commit,
 714                 .event_write = lttng_event_write,
 715                 .event_write_from_user = lttng_event_write_from_user,
 716                 .event_memset = lttng_event_memset,
 717                 .event_strcpy = lttng_event_strcpy,
 718                 .event_strcpy_from_user = lttng_event_strcpy_from_user,
 719                 .packet_avail_size = NULL,      /* Would be racy anyway */
 720                 .get_writer_buf_wait_queue = lttng_get_writer_buf_wait_queue,
 721                 .get_hp_wait_queue = lttng_get_hp_wait_queue,
 722                 .is_finalized = lttng_is_finalized,
 723                 .is_disabled = lttng_is_disabled,
 724                 .timestamp_begin = client_timestamp_begin,
 725                 .timestamp_end = client_timestamp_end,
 726                 .events_discarded = client_events_discarded,
 727                 .content_size = client_content_size,
 728                 .packet_size = client_packet_size,
 729                 .stream_id = client_stream_id,
 730                 .current_timestamp = client_current_timestamp,
 731                 .sequence_number = client_sequence_number,
 732                 .instance_id = client_instance_id,
 733         },
 734 };
 735
 736 static int __init lttng_ring_buffer_client_init(void)
 737 {
 738         /*
 739          * This vmalloc sync all also takes care of the lib ring buffer
 740          * vmalloc'd module pages when it is built as a module into LTTng.
 741          */
 742         wrapper_vmalloc_sync_all();
 743         lttng_transport_register(&lttng_relay_transport);
 744         return 0;
 745 }
 746
 747 module_init(lttng_ring_buffer_client_init);
 748
 749 static void __exit lttng_ring_buffer_client_exit(void)
 750 {
 751         lttng_transport_unregister(&lttng_relay_transport);
 752 }
 753
 754 module_exit(lttng_ring_buffer_client_exit);
 755
 756 MODULE_LICENSE("GPL and additional rights");
 757 MODULE_AUTHOR("Mathieu Desnoyers");
 758 MODULE_DESCRIPTION("LTTng ring buffer " RING_BUFFER_MODE_TEMPLATE_STRING
 759                    " client");