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_probe_ctx *lttng_probe_ctx = ctx->priv;
 134         struct lttng_event *event = lttng_probe_ctx->event;
 135         size_t orig_offset = offset;
 136         size_t padding;
 137
 138         switch (lttng_chan->header_type) {
 139         case 1: /* compact */
 140                 padding = lib_ring_buffer_align(offset, lttng_alignof(uint32_t));
 141                 offset += padding;
 142                 if (!(ctx->rflags & (RING_BUFFER_RFLAG_FULL_TSC | LTTNG_RFLAG_EXTENDED))) {
 143                         offset += sizeof(uint32_t);     /* id and timestamp */
 144                 } else {
 145                         /* Minimum space taken by LTTNG_COMPACT_EVENT_BITS id */
 146                         offset += (LTTNG_COMPACT_EVENT_BITS + CHAR_BIT - 1) / CHAR_BIT;
 147                         /* Align extended struct on largest member */
 148                         offset += lib_ring_buffer_align(offset, lttng_alignof(uint64_t));
 149                         offset += sizeof(uint32_t);     /* id */
 150                         offset += lib_ring_buffer_align(offset, lttng_alignof(uint64_t));
 151                         offset += sizeof(uint64_t);     /* timestamp */
 152                 }
 153                 break;
 154         case 2: /* large */
 155                 padding = lib_ring_buffer_align(offset, lttng_alignof(uint16_t));
 156                 offset += padding;
 157                 offset += sizeof(uint16_t);
 158                 if (!(ctx->rflags & (RING_BUFFER_RFLAG_FULL_TSC | LTTNG_RFLAG_EXTENDED))) {
 159                         offset += lib_ring_buffer_align(offset, lttng_alignof(uint32_t));
 160                         offset += sizeof(uint32_t);     /* timestamp */
 161                 } else {
 162                         /* Align extended struct on largest member */
 163                         offset += lib_ring_buffer_align(offset, lttng_alignof(uint64_t));
 164                         offset += sizeof(uint32_t);     /* id */
 165                         offset += lib_ring_buffer_align(offset, lttng_alignof(uint64_t));
 166                         offset += sizeof(uint64_t);     /* timestamp */
 167                 }
 168                 break;
 169         default:
 170                 padding = 0;
 171                 WARN_ON_ONCE(1);
 172         }
 173         offset += ctx_get_size(offset, lttng_chan->ctx);
 174         offset += ctx_get_size(offset, event->ctx);
 175
 176         *pre_header_padding = padding;
 177         return offset - orig_offset;
 178 }
 179
 180 #include <wrapper/ringbuffer/api.h>
 181
 182 static
 183 void lttng_write_event_header_slow(const struct lib_ring_buffer_config *config,
 184                                  struct lib_ring_buffer_ctx *ctx,
 185                                  uint32_t event_id);
 186
 187 /*
 188  * lttng_write_event_header
 189  *
 190  * Writes the event header to the offset (already aligned on 32-bits).
 191  *
 192  * @config: ring buffer instance configuration
 193  * @ctx: reservation context
 194  * @event_id: event ID
 195  */
 196 static __inline__
 197 void lttng_write_event_header(const struct lib_ring_buffer_config *config,
 198                             struct lib_ring_buffer_ctx *ctx,
 199                             uint32_t event_id)
 200 {
 201         struct lttng_channel *lttng_chan = channel_get_private(ctx->chan);
 202         struct lttng_probe_ctx *lttng_probe_ctx = ctx->priv;
 203         struct lttng_event *event = lttng_probe_ctx->event;
 204
 205         if (unlikely(ctx->rflags))
 206                 goto slow_path;
 207
 208         switch (lttng_chan->header_type) {
 209         case 1: /* compact */
 210         {
 211                 uint32_t id_time = 0;
 212
 213                 bt_bitfield_write(&id_time, uint32_t,
 214                                 0,
 215                                 LTTNG_COMPACT_EVENT_BITS,
 216                                 event_id);
 217                 bt_bitfield_write(&id_time, uint32_t,
 218                                 LTTNG_COMPACT_EVENT_BITS,
 219                                 LTTNG_COMPACT_TSC_BITS,
 220                                 ctx->tsc);
 221                 lib_ring_buffer_write(config, ctx, &id_time, sizeof(id_time));
 222                 break;
 223         }
 224         case 2: /* large */
 225         {
 226                 uint32_t timestamp = (uint32_t) ctx->tsc;
 227                 uint16_t id = event_id;
 228
 229                 lib_ring_buffer_write(config, ctx, &id, sizeof(id));
 230                 lib_ring_buffer_align_ctx(ctx, lttng_alignof(uint32_t));
 231                 lib_ring_buffer_write(config, ctx, &timestamp, sizeof(timestamp));
 232                 break;
 233         }
 234         default:
 235                 WARN_ON_ONCE(1);
 236         }
 237
 238         ctx_record(ctx, lttng_chan, lttng_chan->ctx);
 239         ctx_record(ctx, lttng_chan, event->ctx);
 240         lib_ring_buffer_align_ctx(ctx, ctx->largest_align);
 241
 242         return;
 243
 244 slow_path:
 245         lttng_write_event_header_slow(config, ctx, event_id);
 246 }
 247
 248 static
 249 void lttng_write_event_header_slow(const struct lib_ring_buffer_config *config,
 250                                  struct lib_ring_buffer_ctx *ctx,
 251                                  uint32_t event_id)
 252 {
 253         struct lttng_channel *lttng_chan = channel_get_private(ctx->chan);
 254         struct lttng_probe_ctx *lttng_probe_ctx = ctx->priv;
 255         struct lttng_event *event = lttng_probe_ctx->event;
 256
 257         switch (lttng_chan->header_type) {
 258         case 1: /* compact */
 259                 if (!(ctx->rflags & (RING_BUFFER_RFLAG_FULL_TSC | LTTNG_RFLAG_EXTENDED))) {
 260                         uint32_t id_time = 0;
 261
 262                         bt_bitfield_write(&id_time, uint32_t,
 263                                         0,
 264                                         LTTNG_COMPACT_EVENT_BITS,
 265                                         event_id);
 266                         bt_bitfield_write(&id_time, uint32_t,
 267                                         LTTNG_COMPACT_EVENT_BITS,
 268                                         LTTNG_COMPACT_TSC_BITS, ctx->tsc);
 269                         lib_ring_buffer_write(config, ctx, &id_time, sizeof(id_time));
 270                 } else {
 271                         uint8_t id = 0;
 272                         uint64_t timestamp = ctx->tsc;
 273
 274                         bt_bitfield_write(&id, uint8_t,
 275                                         0,
 276                                         LTTNG_COMPACT_EVENT_BITS,
 277                                         31);
 278                         lib_ring_buffer_write(config, ctx, &id, sizeof(id));
 279                         /* Align extended struct on largest member */
 280                         lib_ring_buffer_align_ctx(ctx, lttng_alignof(uint64_t));
 281                         lib_ring_buffer_write(config, ctx, &event_id, sizeof(event_id));
 282                         lib_ring_buffer_align_ctx(ctx, lttng_alignof(uint64_t));
 283                         lib_ring_buffer_write(config, ctx, &timestamp, sizeof(timestamp));
 284                 }
 285                 break;
 286         case 2: /* large */
 287         {
 288                 if (!(ctx->rflags & (RING_BUFFER_RFLAG_FULL_TSC | LTTNG_RFLAG_EXTENDED))) {
 289                         uint32_t timestamp = (uint32_t) ctx->tsc;
 290                         uint16_t id = event_id;
 291
 292                         lib_ring_buffer_write(config, ctx, &id, sizeof(id));
 293                         lib_ring_buffer_align_ctx(ctx, lttng_alignof(uint32_t));
 294                         lib_ring_buffer_write(config, ctx, &timestamp, sizeof(timestamp));
 295                 } else {
 296                         uint16_t id = 65535;
 297                         uint64_t timestamp = ctx->tsc;
 298
 299                         lib_ring_buffer_write(config, ctx, &id, sizeof(id));
 300                         /* Align extended struct on largest member */
 301                         lib_ring_buffer_align_ctx(ctx, lttng_alignof(uint64_t));
 302                         lib_ring_buffer_write(config, ctx, &event_id, sizeof(event_id));
 303                         lib_ring_buffer_align_ctx(ctx, lttng_alignof(uint64_t));
 304                         lib_ring_buffer_write(config, ctx, &timestamp, sizeof(timestamp));
 305                 }
 306                 break;
 307         }
 308         default:
 309                 WARN_ON_ONCE(1);
 310         }
 311         ctx_record(ctx, lttng_chan, lttng_chan->ctx);
 312         ctx_record(ctx, lttng_chan, event->ctx);
 313         lib_ring_buffer_align_ctx(ctx, ctx->largest_align);
 314 }
 315
 316 static const struct lib_ring_buffer_config client_config;
 317
 318 static u64 client_ring_buffer_clock_read(struct channel *chan)
 319 {
 320         return lib_ring_buffer_clock_read(chan);
 321 }
 322
 323 static
 324 size_t client_record_header_size(const struct lib_ring_buffer_config *config,
 325                                  struct channel *chan, size_t offset,
 326                                  size_t *pre_header_padding,
 327                                  struct lib_ring_buffer_ctx *ctx)
 328 {
 329         return record_header_size(config, chan, offset,
 330                                   pre_header_padding, ctx);
 331 }
 332
 333 /**
 334  * client_packet_header_size - called on buffer-switch to a new sub-buffer
 335  *
 336  * Return header size without padding after the structure. Don't use packed
 337  * structure because gcc generates inefficient code on some architectures
 338  * (powerpc, mips..)
 339  */
 340 static size_t client_packet_header_size(void)
 341 {
 342         return offsetof(struct packet_header, ctx.header_end);
 343 }
 344
 345 static void client_buffer_begin(struct lib_ring_buffer *buf, u64 tsc,
 346                                 unsigned int subbuf_idx)
 347 {
 348         struct channel *chan = buf->backend.chan;
 349         struct packet_header *header =
 350                 (struct packet_header *)
 351                         lib_ring_buffer_offset_address(&buf->backend,
 352                                 subbuf_idx * chan->backend.subbuf_size);
 353         struct lttng_channel *lttng_chan = channel_get_private(chan);
 354         struct lttng_session *session = lttng_chan->session;
 355
 356         header->magic = CTF_MAGIC_NUMBER;
 357         memcpy(header->uuid, session->uuid.b, sizeof(session->uuid));
 358         header->stream_id = lttng_chan->id;
 359         header->stream_instance_id = buf->backend.cpu;
 360         header->ctx.timestamp_begin = tsc;
 361         header->ctx.timestamp_end = 0;
 362         header->ctx.content_size = ~0ULL; /* for debugging */
 363         header->ctx.packet_size = ~0ULL;
 364         header->ctx.packet_seq_num = chan->backend.num_subbuf * \
 365                                      buf->backend.buf_cnt[subbuf_idx].seq_cnt + \
 366                                      subbuf_idx;
 367         header->ctx.events_discarded = 0;
 368         header->ctx.cpu_id = buf->backend.cpu;
 369 }
 370
 371 /*
 372  * offset is assumed to never be 0 here : never deliver a completely empty
 373  * subbuffer. data_size is between 1 and subbuf_size.
 374  */
 375 static void client_buffer_end(struct lib_ring_buffer *buf, u64 tsc,
 376                               unsigned int subbuf_idx, unsigned long data_size)
 377 {
 378         struct channel *chan = buf->backend.chan;
 379         struct packet_header *header =
 380                 (struct packet_header *)
 381                         lib_ring_buffer_offset_address(&buf->backend,
 382                                 subbuf_idx * chan->backend.subbuf_size);
 383         unsigned long records_lost = 0;
 384
 385         header->ctx.timestamp_end = tsc;
 386         header->ctx.content_size =
 387                 (uint64_t) data_size * CHAR_BIT;                /* in bits */
 388         header->ctx.packet_size =
 389                 (uint64_t) PAGE_ALIGN(data_size) * CHAR_BIT;    /* in bits */
 390         records_lost += lib_ring_buffer_get_records_lost_full(&client_config, buf);
 391         records_lost += lib_ring_buffer_get_records_lost_wrap(&client_config, buf);
 392         records_lost += lib_ring_buffer_get_records_lost_big(&client_config, buf);
 393         header->ctx.events_discarded = records_lost;
 394 }
 395
 396 static int client_buffer_create(struct lib_ring_buffer *buf, void *priv,
 397                                 int cpu, const char *name)
 398 {
 399         return 0;
 400 }
 401
 402 static void client_buffer_finalize(struct lib_ring_buffer *buf, void *priv, int cpu)
 403 {
 404 }
 405
 406 static struct packet_header *client_packet_header(
 407                 const struct lib_ring_buffer_config *config,
 408                 struct lib_ring_buffer *buf)
 409 {
 410         return lib_ring_buffer_read_offset_address(&buf->backend, 0);
 411 }
 412
 413 static int client_timestamp_begin(const struct lib_ring_buffer_config *config,
 414                 struct lib_ring_buffer *buf,
 415                 uint64_t *timestamp_begin)
 416 {
 417         struct packet_header *header = client_packet_header(config, buf);
 418         *timestamp_begin = header->ctx.timestamp_begin;
 419
 420         return 0;
 421 }
 422
 423 static int client_timestamp_end(const struct lib_ring_buffer_config *config,
 424                         struct lib_ring_buffer *buf,
 425                         uint64_t *timestamp_end)
 426 {
 427         struct packet_header *header = client_packet_header(config, buf);
 428         *timestamp_end = header->ctx.timestamp_end;
 429
 430         return 0;
 431 }
 432
 433 static int client_events_discarded(const struct lib_ring_buffer_config *config,
 434                         struct lib_ring_buffer *buf,
 435                         uint64_t *events_discarded)
 436 {
 437         struct packet_header *header = client_packet_header(config, buf);
 438         *events_discarded = header->ctx.events_discarded;
 439
 440         return 0;
 441 }
 442
 443 static int client_content_size(const struct lib_ring_buffer_config *config,
 444                         struct lib_ring_buffer *buf,
 445                         uint64_t *content_size)
 446 {
 447         struct packet_header *header = client_packet_header(config, buf);
 448         *content_size = header->ctx.content_size;
 449
 450         return 0;
 451 }
 452
 453 static int client_packet_size(const struct lib_ring_buffer_config *config,
 454                         struct lib_ring_buffer *buf,
 455                         uint64_t *packet_size)
 456 {
 457         struct packet_header *header = client_packet_header(config, buf);
 458         *packet_size = header->ctx.packet_size;
 459
 460         return 0;
 461 }
 462
 463 static int client_stream_id(const struct lib_ring_buffer_config *config,
 464                         struct lib_ring_buffer *buf,
 465                         uint64_t *stream_id)
 466 {
 467         struct packet_header *header = client_packet_header(config, buf);
 468         *stream_id = header->stream_id;
 469
 470         return 0;
 471 }
 472
 473 static int client_current_timestamp(const struct lib_ring_buffer_config *config,
 474                 struct lib_ring_buffer *bufb,
 475                 uint64_t *ts)
 476 {
 477         *ts = config->cb.ring_buffer_clock_read(bufb->backend.chan);
 478
 479         return 0;
 480 }
 481
 482 static int client_sequence_number(const struct lib_ring_buffer_config *config,
 483                         struct lib_ring_buffer *buf,
 484                         uint64_t *seq)
 485 {
 486         struct packet_header *header = client_packet_header(config, buf);
 487
 488         *seq = header->ctx.packet_seq_num;
 489
 490         return 0;
 491 }
 492
 493 static
 494 int client_instance_id(const struct lib_ring_buffer_config *config,
 495                 struct lib_ring_buffer *buf,
 496                 uint64_t *id)
 497 {
 498         struct packet_header *header = client_packet_header(config, buf);
 499         *id = header->stream_instance_id;
 500
 501         return 0;
 502 }
 503
 504 static const struct lib_ring_buffer_config client_config = {
 505         .cb.ring_buffer_clock_read = client_ring_buffer_clock_read,
 506         .cb.record_header_size = client_record_header_size,
 507         .cb.subbuffer_header_size = client_packet_header_size,
 508         .cb.buffer_begin = client_buffer_begin,
 509         .cb.buffer_end = client_buffer_end,
 510         .cb.buffer_create = client_buffer_create,
 511         .cb.buffer_finalize = client_buffer_finalize,
 512
 513         .tsc_bits = LTTNG_COMPACT_TSC_BITS,
 514         .alloc = RING_BUFFER_ALLOC_PER_CPU,
 515         .sync = RING_BUFFER_SYNC_PER_CPU,
 516         .mode = RING_BUFFER_MODE_TEMPLATE,
 517         .backend = RING_BUFFER_PAGE,
 518         .output = RING_BUFFER_OUTPUT_TEMPLATE,
 519         .oops = RING_BUFFER_OOPS_CONSISTENCY,
 520         .ipi = RING_BUFFER_IPI_BARRIER,
 521         .wakeup = RING_BUFFER_WAKEUP_BY_TIMER,
 522 };
 523
 524 static
 525 void release_priv_ops(void *priv_ops)
 526 {
 527         module_put(THIS_MODULE);
 528 }
 529
 530 static
 531 void lttng_channel_destroy(struct channel *chan)
 532 {
 533         channel_destroy(chan);
 534 }
 535
 536 static
 537 struct channel *_channel_create(const char *name,
 538                                 struct lttng_channel *lttng_chan, void *buf_addr,
 539                                 size_t subbuf_size, size_t num_subbuf,
 540                                 unsigned int switch_timer_interval,
 541                                 unsigned int read_timer_interval)
 542 {
 543         struct channel *chan;
 544
 545         chan = channel_create(&client_config, name, lttng_chan, buf_addr,
 546                               subbuf_size, num_subbuf, switch_timer_interval,
 547                               read_timer_interval);
 548         if (chan) {
 549                 /*
 550                  * Ensure this module is not unloaded before we finish
 551                  * using lttng_relay_transport.ops.
 552                  */
 553                 if (!try_module_get(THIS_MODULE)) {
 554                         printk(KERN_WARNING "LTT : Can't lock transport module.\n");
 555                         goto error;
 556                 }
 557                 chan->backend.priv_ops = &lttng_relay_transport.ops;
 558                 chan->backend.release_priv_ops = release_priv_ops;
 559         }
 560         return chan;
 561
 562 error:
 563         lttng_channel_destroy(chan);
 564         return NULL;
 565 }
 566
 567 static
 568 struct lib_ring_buffer *lttng_buffer_read_open(struct channel *chan)
 569 {
 570         struct lib_ring_buffer *buf;
 571         int cpu;
 572
 573         for_each_channel_cpu(cpu, chan) {
 574                 buf = channel_get_ring_buffer(&client_config, chan, cpu);
 575                 if (!lib_ring_buffer_open_read(buf))
 576                         return buf;
 577         }
 578         return NULL;
 579 }
 580
 581 static
 582 int lttng_buffer_has_read_closed_stream(struct channel *chan)
 583 {
 584         struct lib_ring_buffer *buf;
 585         int cpu;
 586
 587         for_each_channel_cpu(cpu, chan) {
 588                 buf = channel_get_ring_buffer(&client_config, chan, cpu);
 589                 if (!atomic_long_read(&buf->active_readers))
 590                         return 1;
 591         }
 592         return 0;
 593 }
 594
 595 static
 596 void lttng_buffer_read_close(struct lib_ring_buffer *buf)
 597 {
 598         lib_ring_buffer_release_read(buf);
 599 }
 600
 601 static
 602 int lttng_event_reserve(struct lib_ring_buffer_ctx *ctx,
 603                       uint32_t event_id)
 604 {
 605         struct lttng_channel *lttng_chan = channel_get_private(ctx->chan);
 606         int ret, cpu;
 607
 608         cpu = lib_ring_buffer_get_cpu(&client_config);
 609         if (cpu < 0)
 610                 return -EPERM;
 611         ctx->cpu = cpu;
 612
 613         switch (lttng_chan->header_type) {
 614         case 1: /* compact */
 615                 if (event_id > 30)
 616                         ctx->rflags |= LTTNG_RFLAG_EXTENDED;
 617                 break;
 618         case 2: /* large */
 619                 if (event_id > 65534)
 620                         ctx->rflags |= LTTNG_RFLAG_EXTENDED;
 621                 break;
 622         default:
 623                 WARN_ON_ONCE(1);
 624         }
 625
 626         ret = lib_ring_buffer_reserve(&client_config, ctx);
 627         if (ret)
 628                 goto put;
 629         lttng_write_event_header(&client_config, ctx, event_id);
 630         return 0;
 631 put:
 632         lib_ring_buffer_put_cpu(&client_config);
 633         return ret;
 634 }
 635
 636 static
 637 void lttng_event_commit(struct lib_ring_buffer_ctx *ctx)
 638 {
 639         lib_ring_buffer_commit(&client_config, ctx);
 640         lib_ring_buffer_put_cpu(&client_config);
 641 }
 642
 643 static
 644 void lttng_event_write(struct lib_ring_buffer_ctx *ctx, const void *src,
 645                      size_t len)
 646 {
 647         lib_ring_buffer_write(&client_config, ctx, src, len);
 648 }
 649
 650 static
 651 void lttng_event_write_from_user(struct lib_ring_buffer_ctx *ctx,
 652                                const void __user *src, size_t len)
 653 {
 654         lib_ring_buffer_copy_from_user_inatomic(&client_config, ctx, src, len);
 655 }
 656
 657 static
 658 void lttng_event_memset(struct lib_ring_buffer_ctx *ctx,
 659                 int c, size_t len)
 660 {
 661         lib_ring_buffer_memset(&client_config, ctx, c, len);
 662 }
 663
 664 static
 665 void lttng_event_strcpy(struct lib_ring_buffer_ctx *ctx, const char *src,
 666                 size_t len)
 667 {
 668         lib_ring_buffer_strcpy(&client_config, ctx, src, len, '#');
 669 }
 670
 671 static
 672 void lttng_event_strcpy_from_user(struct lib_ring_buffer_ctx *ctx,
 673                 const char __user *src, size_t len)
 674 {
 675         lib_ring_buffer_strcpy_from_user_inatomic(&client_config, ctx, src,
 676                         len, '#');
 677 }
 678
 679 static
 680 wait_queue_head_t *lttng_get_writer_buf_wait_queue(struct channel *chan, int cpu)
 681 {
 682         struct lib_ring_buffer *buf = channel_get_ring_buffer(&client_config,
 683                                         chan, cpu);
 684         return &buf->write_wait;
 685 }
 686
 687 static
 688 wait_queue_head_t *lttng_get_hp_wait_queue(struct channel *chan)
 689 {
 690         return &chan->hp_wait;
 691 }
 692
 693 static
 694 int lttng_is_finalized(struct channel *chan)
 695 {
 696         return lib_ring_buffer_channel_is_finalized(chan);
 697 }
 698
 699 static
 700 int lttng_is_disabled(struct channel *chan)
 701 {
 702         return lib_ring_buffer_channel_is_disabled(chan);
 703 }
 704
 705 static struct lttng_transport lttng_relay_transport = {
 706         .name = "relay-" RING_BUFFER_MODE_TEMPLATE_STRING,
 707         .owner = THIS_MODULE,
 708         .ops = {
 709                 .channel_create = _channel_create,
 710                 .channel_destroy = lttng_channel_destroy,
 711                 .buffer_read_open = lttng_buffer_read_open,
 712                 .buffer_has_read_closed_stream =
 713                         lttng_buffer_has_read_closed_stream,
 714                 .buffer_read_close = lttng_buffer_read_close,
 715                 .event_reserve = lttng_event_reserve,
 716                 .event_commit = lttng_event_commit,
 717                 .event_write = lttng_event_write,
 718                 .event_write_from_user = lttng_event_write_from_user,
 719                 .event_memset = lttng_event_memset,
 720                 .event_strcpy = lttng_event_strcpy,
 721                 .event_strcpy_from_user = lttng_event_strcpy_from_user,
 722                 .packet_avail_size = NULL,      /* Would be racy anyway */
 723                 .get_writer_buf_wait_queue = lttng_get_writer_buf_wait_queue,
 724                 .get_hp_wait_queue = lttng_get_hp_wait_queue,
 725                 .is_finalized = lttng_is_finalized,
 726                 .is_disabled = lttng_is_disabled,
 727                 .timestamp_begin = client_timestamp_begin,
 728                 .timestamp_end = client_timestamp_end,
 729                 .events_discarded = client_events_discarded,
 730                 .content_size = client_content_size,
 731                 .packet_size = client_packet_size,
 732                 .stream_id = client_stream_id,
 733                 .current_timestamp = client_current_timestamp,
 734                 .sequence_number = client_sequence_number,
 735                 .instance_id = client_instance_id,
 736         },
 737 };
 738
 739 static int __init lttng_ring_buffer_client_init(void)
 740 {
 741         /*
 742          * This vmalloc sync all also takes care of the lib ring buffer
 743          * vmalloc'd module pages when it is built as a module into LTTng.
 744          */
 745         wrapper_vmalloc_sync_all();
 746         lttng_transport_register(&lttng_relay_transport);
 747         return 0;
 748 }
 749
 750 module_init(lttng_ring_buffer_client_init);
 751
 752 static void __exit lttng_ring_buffer_client_exit(void)
 753 {
 754         lttng_transport_unregister(&lttng_relay_transport);
 755 }
 756
 757 module_exit(lttng_ring_buffer_client_exit);
 758
 759 MODULE_LICENSE("GPL and additional rights");
 760 MODULE_AUTHOR("Mathieu Desnoyers");
 761 MODULE_DESCRIPTION("LTTng ring buffer " RING_BUFFER_MODE_TEMPLATE_STRING
 762                    " client");