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