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 struct lttng_client_ctx {
  80         size_t packet_context_len;
  81         size_t event_context_len;
  82 };
  83
  84 static inline notrace u64 lib_ring_buffer_clock_read(struct channel *chan)
  85 {
  86         return trace_clock_read64();
  87 }
  88
  89 static inline
  90 size_t ctx_get_aligned_size(size_t offset, struct lttng_ctx *ctx,
  91                 size_t ctx_len)
  92 {
  93         size_t orig_offset = offset;
  94
  95         if (likely(!ctx))
  96                 return 0;
  97         offset += lib_ring_buffer_align(offset, ctx->largest_align);
  98         offset += ctx_len;
  99         return offset - orig_offset;
 100 }
 101
 102 static inline
 103 void ctx_get_struct_size(struct lttng_ctx *ctx, size_t *ctx_len,
 104                 struct lttng_channel *chan, struct lib_ring_buffer_ctx *bufctx)
 105 {
 106         int i;
 107         size_t offset = 0;
 108
 109         if (likely(!ctx)) {
 110                 *ctx_len = 0;
 111                 return;
 112         }
 113         for (i = 0; i < ctx->nr_fields; i++) {
 114                 if (ctx->fields[i].get_size)
 115                         offset += ctx->fields[i].get_size(offset);
 116                 if (ctx->fields[i].get_size_arg)
 117                         offset += ctx->fields[i].get_size_arg(offset,
 118                                         &ctx->fields[i], bufctx, chan);
 119         }
 120         *ctx_len = offset;
 121 }
 122
 123 static inline
 124 void ctx_record(struct lib_ring_buffer_ctx *bufctx,
 125                 struct lttng_channel *chan,
 126                 struct lttng_ctx *ctx)
 127 {
 128         int i;
 129
 130         if (likely(!ctx))
 131                 return;
 132         lib_ring_buffer_align_ctx(bufctx, ctx->largest_align);
 133         for (i = 0; i < ctx->nr_fields; i++)
 134                 ctx->fields[i].record(&ctx->fields[i], bufctx, chan);
 135 }
 136
 137 /*
 138  * record_header_size - Calculate the header size and padding necessary.
 139  * @config: ring buffer instance configuration
 140  * @chan: channel
 141  * @offset: offset in the write buffer
 142  * @pre_header_padding: padding to add before the header (output)
 143  * @ctx: reservation context
 144  *
 145  * Returns the event header size (including padding).
 146  *
 147  * The payload must itself determine its own alignment from the biggest type it
 148  * contains.
 149  */
 150 static __inline__
 151 size_t record_header_size(const struct lib_ring_buffer_config *config,
 152                                  struct channel *chan, size_t offset,
 153                                  size_t *pre_header_padding,
 154                                  struct lib_ring_buffer_ctx *ctx,
 155                                  struct lttng_client_ctx *client_ctx)
 156 {
 157         struct lttng_channel *lttng_chan = channel_get_private(chan);
 158         struct lttng_probe_ctx *lttng_probe_ctx = ctx->priv;
 159         struct lttng_event *event = lttng_probe_ctx->event;
 160         size_t orig_offset = offset;
 161         size_t padding;
 162
 163         switch (lttng_chan->header_type) {
 164         case 1: /* compact */
 165                 padding = lib_ring_buffer_align(offset, lttng_alignof(uint32_t));
 166                 offset += padding;
 167                 if (!(ctx->rflags & (RING_BUFFER_RFLAG_FULL_TSC | LTTNG_RFLAG_EXTENDED))) {
 168                         offset += sizeof(uint32_t);     /* id and timestamp */
 169                 } else {
 170                         /* Minimum space taken by LTTNG_COMPACT_EVENT_BITS id */
 171                         offset += (LTTNG_COMPACT_EVENT_BITS + CHAR_BIT - 1) / CHAR_BIT;
 172                         /* Align extended struct on largest member */
 173                         offset += lib_ring_buffer_align(offset, lttng_alignof(uint64_t));
 174                         offset += sizeof(uint32_t);     /* id */
 175                         offset += lib_ring_buffer_align(offset, lttng_alignof(uint64_t));
 176                         offset += sizeof(uint64_t);     /* timestamp */
 177                 }
 178                 break;
 179         case 2: /* large */
 180                 padding = lib_ring_buffer_align(offset, lttng_alignof(uint16_t));
 181                 offset += padding;
 182                 offset += sizeof(uint16_t);
 183                 if (!(ctx->rflags & (RING_BUFFER_RFLAG_FULL_TSC | LTTNG_RFLAG_EXTENDED))) {
 184                         offset += lib_ring_buffer_align(offset, lttng_alignof(uint32_t));
 185                         offset += sizeof(uint32_t);     /* timestamp */
 186                 } else {
 187                         /* Align extended struct on largest member */
 188                         offset += lib_ring_buffer_align(offset, lttng_alignof(uint64_t));
 189                         offset += sizeof(uint32_t);     /* id */
 190                         offset += lib_ring_buffer_align(offset, lttng_alignof(uint64_t));
 191                         offset += sizeof(uint64_t);     /* timestamp */
 192                 }
 193                 break;
 194         default:
 195                 padding = 0;
 196                 WARN_ON_ONCE(1);
 197         }
 198         offset += ctx_get_aligned_size(offset, lttng_chan->ctx,
 199                         client_ctx->packet_context_len);
 200         offset += ctx_get_aligned_size(offset, event->ctx,
 201                         client_ctx->event_context_len);
 202
 203         *pre_header_padding = padding;
 204         return offset - orig_offset;
 205 }
 206
 207 #include <wrapper/ringbuffer/api.h>
 208
 209 static
 210 void lttng_write_event_header_slow(const struct lib_ring_buffer_config *config,
 211                                  struct lib_ring_buffer_ctx *ctx,
 212                                  uint32_t event_id);
 213
 214 /*
 215  * lttng_write_event_header
 216  *
 217  * Writes the event header to the offset (already aligned on 32-bits).
 218  *
 219  * @config: ring buffer instance configuration
 220  * @ctx: reservation context
 221  * @event_id: event ID
 222  */
 223 static __inline__
 224 void lttng_write_event_header(const struct lib_ring_buffer_config *config,
 225                             struct lib_ring_buffer_ctx *ctx,
 226                             uint32_t event_id)
 227 {
 228         struct lttng_channel *lttng_chan = channel_get_private(ctx->chan);
 229         struct lttng_probe_ctx *lttng_probe_ctx = ctx->priv;
 230         struct lttng_event *event = lttng_probe_ctx->event;
 231
 232         if (unlikely(ctx->rflags))
 233                 goto slow_path;
 234
 235         switch (lttng_chan->header_type) {
 236         case 1: /* compact */
 237         {
 238                 uint32_t id_time = 0;
 239
 240                 bt_bitfield_write(&id_time, uint32_t,
 241                                 0,
 242                                 LTTNG_COMPACT_EVENT_BITS,
 243                                 event_id);
 244                 bt_bitfield_write(&id_time, uint32_t,
 245                                 LTTNG_COMPACT_EVENT_BITS,
 246                                 LTTNG_COMPACT_TSC_BITS,
 247                                 ctx->tsc);
 248                 lib_ring_buffer_write(config, ctx, &id_time, sizeof(id_time));
 249                 break;
 250         }
 251         case 2: /* large */
 252         {
 253                 uint32_t timestamp = (uint32_t) ctx->tsc;
 254                 uint16_t id = event_id;
 255
 256                 lib_ring_buffer_write(config, ctx, &id, sizeof(id));
 257                 lib_ring_buffer_align_ctx(ctx, lttng_alignof(uint32_t));
 258                 lib_ring_buffer_write(config, ctx, &timestamp, sizeof(timestamp));
 259                 break;
 260         }
 261         default:
 262                 WARN_ON_ONCE(1);
 263         }
 264
 265         ctx_record(ctx, lttng_chan, lttng_chan->ctx);
 266         ctx_record(ctx, lttng_chan, event->ctx);
 267         lib_ring_buffer_align_ctx(ctx, ctx->largest_align);
 268
 269         return;
 270
 271 slow_path:
 272         lttng_write_event_header_slow(config, ctx, event_id);
 273 }
 274
 275 static
 276 void lttng_write_event_header_slow(const struct lib_ring_buffer_config *config,
 277                                  struct lib_ring_buffer_ctx *ctx,
 278                                  uint32_t event_id)
 279 {
 280         struct lttng_channel *lttng_chan = channel_get_private(ctx->chan);
 281         struct lttng_probe_ctx *lttng_probe_ctx = ctx->priv;
 282         struct lttng_event *event = lttng_probe_ctx->event;
 283
 284         switch (lttng_chan->header_type) {
 285         case 1: /* compact */
 286                 if (!(ctx->rflags & (RING_BUFFER_RFLAG_FULL_TSC | LTTNG_RFLAG_EXTENDED))) {
 287                         uint32_t id_time = 0;
 288
 289                         bt_bitfield_write(&id_time, uint32_t,
 290                                         0,
 291                                         LTTNG_COMPACT_EVENT_BITS,
 292                                         event_id);
 293                         bt_bitfield_write(&id_time, uint32_t,
 294                                         LTTNG_COMPACT_EVENT_BITS,
 295                                         LTTNG_COMPACT_TSC_BITS, ctx->tsc);
 296                         lib_ring_buffer_write(config, ctx, &id_time, sizeof(id_time));
 297                 } else {
 298                         uint8_t id = 0;
 299                         uint64_t timestamp = ctx->tsc;
 300
 301                         bt_bitfield_write(&id, uint8_t,
 302                                         0,
 303                                         LTTNG_COMPACT_EVENT_BITS,
 304                                         31);
 305                         lib_ring_buffer_write(config, ctx, &id, sizeof(id));
 306                         /* Align extended struct on largest member */
 307                         lib_ring_buffer_align_ctx(ctx, lttng_alignof(uint64_t));
 308                         lib_ring_buffer_write(config, ctx, &event_id, sizeof(event_id));
 309                         lib_ring_buffer_align_ctx(ctx, lttng_alignof(uint64_t));
 310                         lib_ring_buffer_write(config, ctx, &timestamp, sizeof(timestamp));
 311                 }
 312                 break;
 313         case 2: /* large */
 314         {
 315                 if (!(ctx->rflags & (RING_BUFFER_RFLAG_FULL_TSC | LTTNG_RFLAG_EXTENDED))) {
 316                         uint32_t timestamp = (uint32_t) ctx->tsc;
 317                         uint16_t id = event_id;
 318
 319                         lib_ring_buffer_write(config, ctx, &id, sizeof(id));
 320                         lib_ring_buffer_align_ctx(ctx, lttng_alignof(uint32_t));
 321                         lib_ring_buffer_write(config, ctx, &timestamp, sizeof(timestamp));
 322                 } else {
 323                         uint16_t id = 65535;
 324                         uint64_t timestamp = ctx->tsc;
 325
 326                         lib_ring_buffer_write(config, ctx, &id, sizeof(id));
 327                         /* Align extended struct on largest member */
 328                         lib_ring_buffer_align_ctx(ctx, lttng_alignof(uint64_t));
 329                         lib_ring_buffer_write(config, ctx, &event_id, sizeof(event_id));
 330                         lib_ring_buffer_align_ctx(ctx, lttng_alignof(uint64_t));
 331                         lib_ring_buffer_write(config, ctx, &timestamp, sizeof(timestamp));
 332                 }
 333                 break;
 334         }
 335         default:
 336                 WARN_ON_ONCE(1);
 337         }
 338         ctx_record(ctx, lttng_chan, lttng_chan->ctx);
 339         ctx_record(ctx, lttng_chan, event->ctx);
 340         lib_ring_buffer_align_ctx(ctx, ctx->largest_align);
 341 }
 342
 343 static const struct lib_ring_buffer_config client_config;
 344
 345 static u64 client_ring_buffer_clock_read(struct channel *chan)
 346 {
 347         return lib_ring_buffer_clock_read(chan);
 348 }
 349
 350 static
 351 size_t client_record_header_size(const struct lib_ring_buffer_config *config,
 352                                  struct channel *chan, size_t offset,
 353                                  size_t *pre_header_padding,
 354                                  struct lib_ring_buffer_ctx *ctx,
 355                                  void *client_ctx)
 356 {
 357         return record_header_size(config, chan, offset,
 358                                   pre_header_padding, ctx, client_ctx);
 359 }
 360
 361 /**
 362  * client_packet_header_size - called on buffer-switch to a new sub-buffer
 363  *
 364  * Return header size without padding after the structure. Don't use packed
 365  * structure because gcc generates inefficient code on some architectures
 366  * (powerpc, mips..)
 367  */
 368 static size_t client_packet_header_size(void)
 369 {
 370         return offsetof(struct packet_header, ctx.header_end);
 371 }
 372
 373 static void client_buffer_begin(struct lib_ring_buffer *buf, u64 tsc,
 374                                 unsigned int subbuf_idx)
 375 {
 376         struct channel *chan = buf->backend.chan;
 377         struct packet_header *header =
 378                 (struct packet_header *)
 379                         lib_ring_buffer_offset_address(&buf->backend,
 380                                 subbuf_idx * chan->backend.subbuf_size);
 381         struct lttng_channel *lttng_chan = channel_get_private(chan);
 382         struct lttng_session *session = lttng_chan->session;
 383
 384         header->magic = CTF_MAGIC_NUMBER;
 385         memcpy(header->uuid, session->uuid.b, sizeof(session->uuid));
 386         header->stream_id = lttng_chan->id;
 387         header->stream_instance_id = buf->backend.cpu;
 388         header->ctx.timestamp_begin = tsc;
 389         header->ctx.timestamp_end = 0;
 390         header->ctx.content_size = ~0ULL; /* for debugging */
 391         header->ctx.packet_size = ~0ULL;
 392         header->ctx.packet_seq_num = chan->backend.num_subbuf * \
 393                                      buf->backend.buf_cnt[subbuf_idx].seq_cnt + \
 394                                      subbuf_idx;
 395         header->ctx.events_discarded = 0;
 396         header->ctx.cpu_id = buf->backend.cpu;
 397 }
 398
 399 /*
 400  * offset is assumed to never be 0 here : never deliver a completely empty
 401  * subbuffer. data_size is between 1 and subbuf_size.
 402  */
 403 static void client_buffer_end(struct lib_ring_buffer *buf, u64 tsc,
 404                               unsigned int subbuf_idx, unsigned long data_size)
 405 {
 406         struct channel *chan = buf->backend.chan;
 407         struct packet_header *header =
 408                 (struct packet_header *)
 409                         lib_ring_buffer_offset_address(&buf->backend,
 410                                 subbuf_idx * chan->backend.subbuf_size);
 411         unsigned long records_lost = 0;
 412
 413         header->ctx.timestamp_end = tsc;
 414         header->ctx.content_size =
 415                 (uint64_t) data_size * CHAR_BIT;                /* in bits */
 416         header->ctx.packet_size =
 417                 (uint64_t) PAGE_ALIGN(data_size) * CHAR_BIT;    /* in bits */
 418         records_lost += lib_ring_buffer_get_records_lost_full(&client_config, buf);
 419         records_lost += lib_ring_buffer_get_records_lost_wrap(&client_config, buf);
 420         records_lost += lib_ring_buffer_get_records_lost_big(&client_config, buf);
 421         header->ctx.events_discarded = records_lost;
 422 }
 423
 424 static int client_buffer_create(struct lib_ring_buffer *buf, void *priv,
 425                                 int cpu, const char *name)
 426 {
 427         return 0;
 428 }
 429
 430 static void client_buffer_finalize(struct lib_ring_buffer *buf, void *priv, int cpu)
 431 {
 432 }
 433
 434 static struct packet_header *client_packet_header(
 435                 const struct lib_ring_buffer_config *config,
 436                 struct lib_ring_buffer *buf)
 437 {
 438         return lib_ring_buffer_read_offset_address(&buf->backend, 0);
 439 }
 440
 441 static int client_timestamp_begin(const struct lib_ring_buffer_config *config,
 442                 struct lib_ring_buffer *buf,
 443                 uint64_t *timestamp_begin)
 444 {
 445         struct packet_header *header = client_packet_header(config, buf);
 446         *timestamp_begin = header->ctx.timestamp_begin;
 447
 448         return 0;
 449 }
 450
 451 static int client_timestamp_end(const struct lib_ring_buffer_config *config,
 452                         struct lib_ring_buffer *buf,
 453                         uint64_t *timestamp_end)
 454 {
 455         struct packet_header *header = client_packet_header(config, buf);
 456         *timestamp_end = header->ctx.timestamp_end;
 457
 458         return 0;
 459 }
 460
 461 static int client_events_discarded(const struct lib_ring_buffer_config *config,
 462                         struct lib_ring_buffer *buf,
 463                         uint64_t *events_discarded)
 464 {
 465         struct packet_header *header = client_packet_header(config, buf);
 466         *events_discarded = header->ctx.events_discarded;
 467
 468         return 0;
 469 }
 470
 471 static int client_content_size(const struct lib_ring_buffer_config *config,
 472                         struct lib_ring_buffer *buf,
 473                         uint64_t *content_size)
 474 {
 475         struct packet_header *header = client_packet_header(config, buf);
 476         *content_size = header->ctx.content_size;
 477
 478         return 0;
 479 }
 480
 481 static int client_packet_size(const struct lib_ring_buffer_config *config,
 482                         struct lib_ring_buffer *buf,
 483                         uint64_t *packet_size)
 484 {
 485         struct packet_header *header = client_packet_header(config, buf);
 486         *packet_size = header->ctx.packet_size;
 487
 488         return 0;
 489 }
 490
 491 static int client_stream_id(const struct lib_ring_buffer_config *config,
 492                         struct lib_ring_buffer *buf,
 493                         uint64_t *stream_id)
 494 {
 495         struct packet_header *header = client_packet_header(config, buf);
 496         *stream_id = header->stream_id;
 497
 498         return 0;
 499 }
 500
 501 static int client_current_timestamp(const struct lib_ring_buffer_config *config,
 502                 struct lib_ring_buffer *bufb,
 503                 uint64_t *ts)
 504 {
 505         *ts = config->cb.ring_buffer_clock_read(bufb->backend.chan);
 506
 507         return 0;
 508 }
 509
 510 static int client_sequence_number(const struct lib_ring_buffer_config *config,
 511                         struct lib_ring_buffer *buf,
 512                         uint64_t *seq)
 513 {
 514         struct packet_header *header = client_packet_header(config, buf);
 515
 516         *seq = header->ctx.packet_seq_num;
 517
 518         return 0;
 519 }
 520
 521 static
 522 int client_instance_id(const struct lib_ring_buffer_config *config,
 523                 struct lib_ring_buffer *buf,
 524                 uint64_t *id)
 525 {
 526         struct packet_header *header = client_packet_header(config, buf);
 527         *id = header->stream_instance_id;
 528
 529         return 0;
 530 }
 531
 532 static const struct lib_ring_buffer_config client_config = {
 533         .cb.ring_buffer_clock_read = client_ring_buffer_clock_read,
 534         .cb.record_header_size = client_record_header_size,
 535         .cb.subbuffer_header_size = client_packet_header_size,
 536         .cb.buffer_begin = client_buffer_begin,
 537         .cb.buffer_end = client_buffer_end,
 538         .cb.buffer_create = client_buffer_create,
 539         .cb.buffer_finalize = client_buffer_finalize,
 540
 541         .tsc_bits = LTTNG_COMPACT_TSC_BITS,
 542         .alloc = RING_BUFFER_ALLOC_PER_CPU,
 543         .sync = RING_BUFFER_SYNC_PER_CPU,
 544         .mode = RING_BUFFER_MODE_TEMPLATE,
 545         .backend = RING_BUFFER_PAGE,
 546         .output = RING_BUFFER_OUTPUT_TEMPLATE,
 547         .oops = RING_BUFFER_OOPS_CONSISTENCY,
 548         .ipi = RING_BUFFER_IPI_BARRIER,
 549         .wakeup = RING_BUFFER_WAKEUP_BY_TIMER,
 550 };
 551
 552 static
 553 void release_priv_ops(void *priv_ops)
 554 {
 555         module_put(THIS_MODULE);
 556 }
 557
 558 static
 559 void lttng_channel_destroy(struct channel *chan)
 560 {
 561         channel_destroy(chan);
 562 }
 563
 564 static
 565 struct channel *_channel_create(const char *name,
 566                                 struct lttng_channel *lttng_chan, void *buf_addr,
 567                                 size_t subbuf_size, size_t num_subbuf,
 568                                 unsigned int switch_timer_interval,
 569                                 unsigned int read_timer_interval)
 570 {
 571         struct channel *chan;
 572
 573         chan = channel_create(&client_config, name, lttng_chan, buf_addr,
 574                               subbuf_size, num_subbuf, switch_timer_interval,
 575                               read_timer_interval);
 576         if (chan) {
 577                 /*
 578                  * Ensure this module is not unloaded before we finish
 579                  * using lttng_relay_transport.ops.
 580                  */
 581                 if (!try_module_get(THIS_MODULE)) {
 582                         printk(KERN_WARNING "LTT : Can't lock transport module.\n");
 583                         goto error;
 584                 }
 585                 chan->backend.priv_ops = &lttng_relay_transport.ops;
 586                 chan->backend.release_priv_ops = release_priv_ops;
 587         }
 588         return chan;
 589
 590 error:
 591         lttng_channel_destroy(chan);
 592         return NULL;
 593 }
 594
 595 static
 596 struct lib_ring_buffer *lttng_buffer_read_open(struct channel *chan)
 597 {
 598         struct lib_ring_buffer *buf;
 599         int cpu;
 600
 601         for_each_channel_cpu(cpu, chan) {
 602                 buf = channel_get_ring_buffer(&client_config, chan, cpu);
 603                 if (!lib_ring_buffer_open_read(buf))
 604                         return buf;
 605         }
 606         return NULL;
 607 }
 608
 609 static
 610 int lttng_buffer_has_read_closed_stream(struct channel *chan)
 611 {
 612         struct lib_ring_buffer *buf;
 613         int cpu;
 614
 615         for_each_channel_cpu(cpu, chan) {
 616                 buf = channel_get_ring_buffer(&client_config, chan, cpu);
 617                 if (!atomic_long_read(&buf->active_readers))
 618                         return 1;
 619         }
 620         return 0;
 621 }
 622
 623 static
 624 void lttng_buffer_read_close(struct lib_ring_buffer *buf)
 625 {
 626         lib_ring_buffer_release_read(buf);
 627 }
 628
 629 static
 630 int lttng_event_reserve(struct lib_ring_buffer_ctx *ctx,
 631                       uint32_t event_id)
 632 {
 633         struct lttng_channel *lttng_chan = channel_get_private(ctx->chan);
 634         struct lttng_probe_ctx *lttng_probe_ctx = ctx->priv;
 635         struct lttng_event *event = lttng_probe_ctx->event;
 636         struct lttng_client_ctx client_ctx;
 637         int ret, cpu;
 638
 639         cpu = lib_ring_buffer_get_cpu(&client_config);
 640         if (unlikely(cpu < 0))
 641                 return -EPERM;
 642         ctx->cpu = cpu;
 643
 644         /* Compute internal size of context structures. */
 645         ctx_get_struct_size(lttng_chan->ctx, &client_ctx.packet_context_len, lttng_chan, ctx);
 646         ctx_get_struct_size(event->ctx, &client_ctx.event_context_len, lttng_chan, ctx);
 647
 648         switch (lttng_chan->header_type) {
 649         case 1: /* compact */
 650                 if (event_id > 30)
 651                         ctx->rflags |= LTTNG_RFLAG_EXTENDED;
 652                 break;
 653         case 2: /* large */
 654                 if (event_id > 65534)
 655                         ctx->rflags |= LTTNG_RFLAG_EXTENDED;
 656                 break;
 657         default:
 658                 WARN_ON_ONCE(1);
 659         }
 660
 661         ret = lib_ring_buffer_reserve(&client_config, ctx, &client_ctx);
 662         if (unlikely(ret))
 663                 goto put;
 664         lib_ring_buffer_backend_get_pages(&client_config, ctx,
 665                         &ctx->backend_pages);
 666         lttng_write_event_header(&client_config, ctx, event_id);
 667         return 0;
 668 put:
 669         lib_ring_buffer_put_cpu(&client_config);
 670         return ret;
 671 }
 672
 673 static
 674 void lttng_event_commit(struct lib_ring_buffer_ctx *ctx)
 675 {
 676         lib_ring_buffer_commit(&client_config, ctx);
 677         lib_ring_buffer_put_cpu(&client_config);
 678 }
 679
 680 static
 681 void lttng_event_write(struct lib_ring_buffer_ctx *ctx, const void *src,
 682                      size_t len)
 683 {
 684         lib_ring_buffer_write(&client_config, ctx, src, len);
 685 }
 686
 687 static
 688 void lttng_event_write_from_user(struct lib_ring_buffer_ctx *ctx,
 689                                const void __user *src, size_t len)
 690 {
 691         lib_ring_buffer_copy_from_user_inatomic(&client_config, ctx, src, len);
 692 }
 693
 694 static
 695 void lttng_event_memset(struct lib_ring_buffer_ctx *ctx,
 696                 int c, size_t len)
 697 {
 698         lib_ring_buffer_memset(&client_config, ctx, c, len);
 699 }
 700
 701 static
 702 void lttng_event_strcpy(struct lib_ring_buffer_ctx *ctx, const char *src,
 703                 size_t len)
 704 {
 705         lib_ring_buffer_strcpy(&client_config, ctx, src, len, '#');
 706 }
 707
 708 static
 709 void lttng_event_strcpy_from_user(struct lib_ring_buffer_ctx *ctx,
 710                 const char __user *src, size_t len)
 711 {
 712         lib_ring_buffer_strcpy_from_user_inatomic(&client_config, ctx, src,
 713                         len, '#');
 714 }
 715
 716 static
 717 wait_queue_head_t *lttng_get_writer_buf_wait_queue(struct channel *chan, int cpu)
 718 {
 719         struct lib_ring_buffer *buf = channel_get_ring_buffer(&client_config,
 720                                         chan, cpu);
 721         return &buf->write_wait;
 722 }
 723
 724 static
 725 wait_queue_head_t *lttng_get_hp_wait_queue(struct channel *chan)
 726 {
 727         return &chan->hp_wait;
 728 }
 729
 730 static
 731 int lttng_is_finalized(struct channel *chan)
 732 {
 733         return lib_ring_buffer_channel_is_finalized(chan);
 734 }
 735
 736 static
 737 int lttng_is_disabled(struct channel *chan)
 738 {
 739         return lib_ring_buffer_channel_is_disabled(chan);
 740 }
 741
 742 static struct lttng_transport lttng_relay_transport = {
 743         .name = "relay-" RING_BUFFER_MODE_TEMPLATE_STRING,
 744         .owner = THIS_MODULE,
 745         .ops = {
 746                 .channel_create = _channel_create,
 747                 .channel_destroy = lttng_channel_destroy,
 748                 .buffer_read_open = lttng_buffer_read_open,
 749                 .buffer_has_read_closed_stream =
 750                         lttng_buffer_has_read_closed_stream,
 751                 .buffer_read_close = lttng_buffer_read_close,
 752                 .event_reserve = lttng_event_reserve,
 753                 .event_commit = lttng_event_commit,
 754                 .event_write = lttng_event_write,
 755                 .event_write_from_user = lttng_event_write_from_user,
 756                 .event_memset = lttng_event_memset,
 757                 .event_strcpy = lttng_event_strcpy,
 758                 .event_strcpy_from_user = lttng_event_strcpy_from_user,
 759                 .packet_avail_size = NULL,      /* Would be racy anyway */
 760                 .get_writer_buf_wait_queue = lttng_get_writer_buf_wait_queue,
 761                 .get_hp_wait_queue = lttng_get_hp_wait_queue,
 762                 .is_finalized = lttng_is_finalized,
 763                 .is_disabled = lttng_is_disabled,
 764                 .timestamp_begin = client_timestamp_begin,
 765                 .timestamp_end = client_timestamp_end,
 766                 .events_discarded = client_events_discarded,
 767                 .content_size = client_content_size,
 768                 .packet_size = client_packet_size,
 769                 .stream_id = client_stream_id,
 770                 .current_timestamp = client_current_timestamp,
 771                 .sequence_number = client_sequence_number,
 772                 .instance_id = client_instance_id,
 773         },
 774 };
 775
 776 static int __init lttng_ring_buffer_client_init(void)
 777 {
 778         /*
 779          * This vmalloc sync all also takes care of the lib ring buffer
 780          * vmalloc'd module pages when it is built as a module into LTTng.
 781          */
 782         wrapper_vmalloc_sync_all();
 783         lttng_transport_register(&lttng_relay_transport);
 784         return 0;
 785 }
 786
 787 module_init(lttng_ring_buffer_client_init);
 788
 789 static void __exit lttng_ring_buffer_client_exit(void)
 790 {
 791         lttng_transport_unregister(&lttng_relay_transport);
 792 }
 793
 794 module_exit(lttng_ring_buffer_client_exit);
 795
 796 MODULE_LICENSE("GPL and additional rights");
 797 MODULE_AUTHOR("Mathieu Desnoyers <mathieu.desnoyers@efficios.com>");
 798 MODULE_DESCRIPTION("LTTng ring buffer " RING_BUFFER_MODE_TEMPLATE_STRING
 799                    " client");
 800 MODULE_VERSION(__stringify(LTTNG_MODULES_MAJOR_VERSION) "."
 801         __stringify(LTTNG_MODULES_MINOR_VERSION) "."
 802         __stringify(LTTNG_MODULES_PATCHLEVEL_VERSION)
 803         LTTNG_MODULES_EXTRAVERSION);