src/common/kernel-consumer/kernel-consumer.cpp

   1 /*
   2  * Copyright (C) 2011 EfficiOS Inc.
   3  * Copyright (C) 2011 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   4  * Copyright (C) 2017 Jérémie Galarneau <jeremie.galarneau@efficios.com>
   5  *
   6  * SPDX-License-Identifier: GPL-2.0-only
   7  *
   8  */
   9
  10 #define _LGPL_SOURCE
  11 #include "kernel-consumer.hpp"
  12
  13 #include <common/buffer-view.hpp>
  14 #include <common/common.hpp>
  15 #include <common/compat/endian.hpp>
  16 #include <common/consumer/consumer-stream.hpp>
  17 #include <common/consumer/consumer-timer.hpp>
  18 #include <common/consumer/consumer.hpp>
  19 #include <common/consumer/metadata-bucket.hpp>
  20 #include <common/index/index.hpp>
  21 #include <common/kernel-ctl/kernel-ctl.hpp>
  22 #include <common/optional.hpp>
  23 #include <common/pipe.hpp>
  24 #include <common/pthread-lock.hpp>
  25 #include <common/relayd/relayd.hpp>
  26 #include <common/scope-exit.hpp>
  27 #include <common/sessiond-comm/relayd.hpp>
  28 #include <common/sessiond-comm/sessiond-comm.hpp>
  29 #include <common/urcu.hpp>
  30 #include <common/utils.hpp>
  31
  32 #include <bin/lttng-consumerd/health-consumerd.hpp>
  33 #include <fcntl.h>
  34 #include <inttypes.h>
  35 #include <poll.h>
  36 #include <pthread.h>
  37 #include <stdint.h>
  38 #include <stdlib.h>
  39 #include <string.h>
  40 #include <sys/mman.h>
  41 #include <sys/socket.h>
  42 #include <sys/stat.h>
  43 #include <sys/types.h>
  44 #include <unistd.h>
  45
  46 extern struct lttng_consumer_global_data the_consumer_data;
  47 extern int consumer_poll_timeout;
  48
  49 /*
  50  * Take a snapshot for a specific fd
  51  *
  52  * Returns 0 on success, < 0 on error
  53  */
  54 int lttng_kconsumer_take_snapshot(struct lttng_consumer_stream *stream)
  55 {
  56         int ret = 0;
  57         const int infd = stream->wait_fd;
  58
  59         ret = kernctl_snapshot(infd);
  60         /*
  61          * -EAGAIN is not an error, it just means that there is no data to
  62          *  be read.
  63          */
  64         if (ret != 0 && ret != -EAGAIN) {
  65                 PERROR("Getting sub-buffer snapshot.");
  66         }
  67
  68         return ret;
  69 }
  70
  71 /*
  72  * Sample consumed and produced positions for a specific fd.
  73  *
  74  * Returns 0 on success, < 0 on error.
  75  */
  76 int lttng_kconsumer_sample_snapshot_positions(struct lttng_consumer_stream *stream)
  77 {
  78         LTTNG_ASSERT(stream);
  79
  80         return kernctl_snapshot_sample_positions(stream->wait_fd);
  81 }
  82
  83 /*
  84  * Get the produced position
  85  *
  86  * Returns 0 on success, < 0 on error
  87  */
  88 int lttng_kconsumer_get_produced_snapshot(struct lttng_consumer_stream *stream, unsigned long *pos)
  89 {
  90         int ret;
  91         const int infd = stream->wait_fd;
  92
  93         ret = kernctl_snapshot_get_produced(infd, pos);
  94         if (ret != 0) {
  95                 PERROR("kernctl_snapshot_get_produced");
  96         }
  97
  98         return ret;
  99 }
 100
 101 /*
 102  * Get the consumerd position
 103  *
 104  * Returns 0 on success, < 0 on error
 105  */
 106 int lttng_kconsumer_get_consumed_snapshot(struct lttng_consumer_stream *stream, unsigned long *pos)
 107 {
 108         int ret;
 109         const int infd = stream->wait_fd;
 110
 111         ret = kernctl_snapshot_get_consumed(infd, pos);
 112         if (ret != 0) {
 113                 PERROR("kernctl_snapshot_get_consumed");
 114         }
 115
 116         return ret;
 117 }
 118
 119 static int get_current_subbuf_addr(struct lttng_consumer_stream *stream, const char **addr)
 120 {
 121         int ret;
 122         unsigned long mmap_offset;
 123         const char *mmap_base = (const char *) stream->mmap_base;
 124
 125         ret = kernctl_get_mmap_read_offset(stream->wait_fd, &mmap_offset);
 126         if (ret < 0) {
 127                 PERROR("Failed to get mmap read offset");
 128                 goto error;
 129         }
 130
 131         *addr = mmap_base + mmap_offset;
 132 error:
 133         return ret;
 134 }
 135
 136 /*
 137  * Take a snapshot of all the stream of a channel
 138  * RCU read-side lock must be held across this function to ensure existence of
 139  * channel.
 140  *
 141  * Returns 0 on success, < 0 on error
 142  */
 143 static int lttng_kconsumer_snapshot_channel(struct lttng_consumer_channel *channel,
 144                                             uint64_t key,
 145                                             char *path,
 146                                             uint64_t relayd_id,
 147                                             uint64_t nb_packets_per_stream)
 148 {
 149         int ret;
 150
 151         DBG("Kernel consumer snapshot channel %" PRIu64, key);
 152
 153         /* Prevent channel modifications while we perform the snapshot.*/
 154         const lttng::pthread::lock_guard channe_lock(channel->lock);
 155
 156         const lttng::urcu::read_lock_guard read_lock;
 157
 158         /* Splice is not supported yet for channel snapshot. */
 159         if (channel->output != CONSUMER_CHANNEL_MMAP) {
 160                 ERR("Unsupported output type for channel \"%s\": mmap output is required to record a snapshot",
 161                     channel->name);
 162                 ret = -1;
 163                 goto end;
 164         }
 165
 166         for (auto stream : lttng::urcu::list_iteration_adapter<lttng_consumer_stream,
 167                                                                &lttng_consumer_stream::send_node>(
 168                      channel->streams.head)) {
 169                 unsigned long consumed_pos, produced_pos;
 170
 171                 health_code_update();
 172
 173                 /*
 174                  * Lock stream because we are about to change its state.
 175                  */
 176                 const lttng::pthread::lock_guard stream_lock(stream->lock);
 177
 178                 LTTNG_ASSERT(channel->trace_chunk);
 179                 if (!lttng_trace_chunk_get(channel->trace_chunk)) {
 180                         /*
 181                          * Can't happen barring an internal error as the channel
 182                          * holds a reference to the trace chunk.
 183                          */
 184                         ERR("Failed to acquire reference to channel's trace chunk");
 185                         ret = -1;
 186                         goto end;
 187                 }
 188                 LTTNG_ASSERT(!stream->trace_chunk);
 189                 stream->trace_chunk = channel->trace_chunk;
 190
 191                 /*
 192                  * Assign the received relayd ID so we can use it for streaming. The streams
 193                  * are not visible to anyone so this is OK to change it.
 194                  */
 195                 stream->net_seq_idx = relayd_id;
 196                 channel->relayd_id = relayd_id;
 197
 198                 /* Close stream output when were are done. */
 199                 const auto close_stream_output = lttng::make_scope_exit(
 200                         [stream]() noexcept { consumer_stream_close_output(stream); });
 201
 202                 if (relayd_id != (uint64_t) -1ULL) {
 203                         ret = consumer_send_relayd_stream(stream, path);
 204                         if (ret < 0) {
 205                                 ERR("sending stream to relayd");
 206                                 goto end;
 207                         }
 208                 } else {
 209                         ret = consumer_stream_create_output_files(stream, false);
 210                         if (ret < 0) {
 211                                 goto end;
 212                         }
 213                         DBG("Kernel consumer snapshot stream (%" PRIu64 ")", stream->key);
 214                 }
 215
 216                 ret = kernctl_buffer_flush_empty(stream->wait_fd);
 217                 if (ret < 0) {
 218                         /*
 219                          * Doing a buffer flush which does not take into
 220                          * account empty packets. This is not perfect
 221                          * for stream intersection, but required as a
 222                          * fall-back when "flush_empty" is not
 223                          * implemented by lttng-modules.
 224                          */
 225                         ret = kernctl_buffer_flush(stream->wait_fd);
 226                         if (ret < 0) {
 227                                 ERR("Failed to flush kernel stream");
 228                                 goto end;
 229                         }
 230                         goto end;
 231                 }
 232
 233                 ret = lttng_kconsumer_take_snapshot(stream);
 234                 if (ret < 0) {
 235                         ERR("Taking kernel snapshot");
 236                         goto end;
 237                 }
 238
 239                 ret = lttng_kconsumer_get_produced_snapshot(stream, &produced_pos);
 240                 if (ret < 0) {
 241                         ERR("Produced kernel snapshot position");
 242                         goto end;
 243                 }
 244
 245                 ret = lttng_kconsumer_get_consumed_snapshot(stream, &consumed_pos);
 246                 if (ret < 0) {
 247                         ERR("Consumerd kernel snapshot position");
 248                         goto end;
 249                 }
 250
 251                 consumed_pos = consumer_get_consume_start_pos(
 252                         consumed_pos, produced_pos, nb_packets_per_stream, stream->max_sb_size);
 253
 254                 while ((long) (consumed_pos - produced_pos) < 0) {
 255                         ssize_t read_len;
 256                         unsigned long len, padded_len;
 257                         const char *subbuf_addr;
 258                         struct lttng_buffer_view subbuf_view;
 259
 260                         health_code_update();
 261                         DBG("Kernel consumer taking snapshot at pos %lu", consumed_pos);
 262
 263                         ret = kernctl_get_subbuf(stream->wait_fd, &consumed_pos);
 264                         if (ret < 0) {
 265                                 if (ret != -EAGAIN) {
 266                                         PERROR("kernctl_get_subbuf snapshot");
 267                                         goto end;
 268                                 }
 269                                 DBG("Kernel consumer get subbuf failed. Skipping it.");
 270                                 consumed_pos += stream->max_sb_size;
 271                                 stream->chan->lost_packets++;
 272                                 continue;
 273                         }
 274
 275                         /* Put the subbuffer once we are done. */
 276                         const auto put_subbuf = lttng::make_scope_exit([stream]() noexcept {
 277                                 const auto put_ret = kernctl_put_subbuf(stream->wait_fd);
 278                                 if (put_ret < 0) {
 279                                         ERR("Snapshot kernctl_put_subbuf");
 280                                 }
 281                         });
 282
 283                         ret = kernctl_get_subbuf_size(stream->wait_fd, &len);
 284                         if (ret < 0) {
 285                                 ERR("Snapshot kernctl_get_subbuf_size");
 286                                 goto end;
 287                         }
 288
 289                         ret = kernctl_get_padded_subbuf_size(stream->wait_fd, &padded_len);
 290                         if (ret < 0) {
 291                                 ERR("Snapshot kernctl_get_padded_subbuf_size");
 292                                 goto end;
 293                         }
 294
 295                         ret = get_current_subbuf_addr(stream, &subbuf_addr);
 296                         if (ret) {
 297                                 goto end;
 298                         }
 299
 300                         subbuf_view = lttng_buffer_view_init(subbuf_addr, 0, padded_len);
 301                         read_len = lttng_consumer_on_read_subbuffer_mmap(
 302                                 stream, &subbuf_view, padded_len - len);
 303                         /*
 304                          * We write the padded len in local tracefiles but the data len
 305                          * when using a relay. Display the error but continue processing
 306                          * to try to release the subbuffer.
 307                          */
 308                         if (relayd_id != (uint64_t) -1ULL) {
 309                                 if (read_len != len) {
 310                                         ERR("Error sending to the relay (ret: %zd != len: %lu)",
 311                                             read_len,
 312                                             len);
 313                                 }
 314                         } else {
 315                                 if (read_len != padded_len) {
 316                                         ERR("Error writing to tracefile (ret: %zd != len: %lu)",
 317                                             read_len,
 318                                             padded_len);
 319                                 }
 320                         }
 321
 322                         consumed_pos += stream->max_sb_size;
 323                 }
 324         }
 325
 326         /* All good! */
 327         ret = 0;
 328         goto end;
 329
 330 end:
 331         return ret;
 332 }
 333
 334 /*
 335  * Read the whole metadata available for a snapshot.
 336  * RCU read-side lock must be held across this function to ensure existence of
 337  * metadata_channel.
 338  *
 339  * Returns 0 on success, < 0 on error
 340  */
 341 static int lttng_kconsumer_snapshot_metadata(struct lttng_consumer_channel *metadata_channel,
 342                                              uint64_t key,
 343                                              char *path,
 344                                              uint64_t relayd_id,
 345                                              struct lttng_consumer_local_data *ctx)
 346 {
 347         int ret, use_relayd = 0;
 348         ssize_t ret_read;
 349         struct lttng_consumer_stream *metadata_stream;
 350
 351         LTTNG_ASSERT(ctx);
 352
 353         DBG("Kernel consumer snapshot metadata with key %" PRIu64 " at path %s", key, path);
 354
 355         const lttng::urcu::read_lock_guard read_lock;
 356
 357         metadata_stream = metadata_channel->metadata_stream;
 358         LTTNG_ASSERT(metadata_stream);
 359
 360         metadata_stream->read_subbuffer_ops.lock(metadata_stream);
 361         LTTNG_ASSERT(metadata_channel->trace_chunk);
 362         LTTNG_ASSERT(metadata_stream->trace_chunk);
 363
 364         /* Flag once that we have a valid relayd for the stream. */
 365         if (relayd_id != (uint64_t) -1ULL) {
 366                 use_relayd = 1;
 367         }
 368
 369         if (use_relayd) {
 370                 ret = consumer_send_relayd_stream(metadata_stream, path);
 371                 if (ret < 0) {
 372                         goto error_snapshot;
 373                 }
 374         } else {
 375                 ret = consumer_stream_create_output_files(metadata_stream, false);
 376                 if (ret < 0) {
 377                         goto error_snapshot;
 378                 }
 379         }
 380
 381         do {
 382                 health_code_update();
 383
 384                 ret_read = lttng_consumer_read_subbuffer(metadata_stream, ctx, true);
 385                 if (ret_read < 0) {
 386                         ERR("Kernel snapshot reading metadata subbuffer (ret: %zd)", ret_read);
 387                         ret = ret_read;
 388                         goto error_snapshot;
 389                 }
 390         } while (ret_read > 0);
 391
 392         if (use_relayd) {
 393                 close_relayd_stream(metadata_stream);
 394                 metadata_stream->net_seq_idx = (uint64_t) -1ULL;
 395         } else {
 396                 if (metadata_stream->out_fd >= 0) {
 397                         ret = close(metadata_stream->out_fd);
 398                         if (ret < 0) {
 399                                 PERROR("Kernel consumer snapshot metadata close out_fd");
 400                                 /*
 401                                  * Don't go on error here since the snapshot was successful at this
 402                                  * point but somehow the close failed.
 403                                  */
 404                         }
 405                         metadata_stream->out_fd = -1;
 406                         lttng_trace_chunk_put(metadata_stream->trace_chunk);
 407                         metadata_stream->trace_chunk = nullptr;
 408                 }
 409         }
 410
 411         ret = 0;
 412 error_snapshot:
 413         metadata_stream->read_subbuffer_ops.unlock(metadata_stream);
 414         consumer_stream_destroy(metadata_stream, nullptr);
 415         metadata_channel->metadata_stream = nullptr;
 416         return ret;
 417 }
 418
 419 /*
 420  * Receive command from session daemon and process it.
 421  *
 422  * Return 1 on success else a negative value or 0.
 423  */
 424 int lttng_kconsumer_recv_cmd(struct lttng_consumer_local_data *ctx,
 425                              int sock,
 426                              struct pollfd *consumer_sockpoll)
 427 {
 428         int ret_func;
 429         enum lttcomm_return_code ret_code = LTTCOMM_CONSUMERD_SUCCESS;
 430         struct lttcomm_consumer_msg msg;
 431
 432         health_code_update();
 433
 434         {
 435                 ssize_t ret_recv;
 436
 437                 ret_recv = lttcomm_recv_unix_sock(sock, &msg, sizeof(msg));
 438                 if (ret_recv != sizeof(msg)) {
 439                         if (ret_recv > 0) {
 440                                 lttng_consumer_send_error(ctx, LTTCOMM_CONSUMERD_ERROR_RECV_CMD);
 441                                 ret_recv = -1;
 442                         }
 443                         return ret_recv;
 444                 }
 445         }
 446
 447         health_code_update();
 448
 449         /* Deprecated command */
 450         LTTNG_ASSERT(msg.cmd_type != LTTNG_CONSUMER_STOP);
 451
 452         health_code_update();
 453
 454         /* relayd needs RCU read-side protection */
 455         const lttng::urcu::read_lock_guard read_lock;
 456
 457         switch (msg.cmd_type) {
 458         case LTTNG_CONSUMER_ADD_RELAYD_SOCKET:
 459         {
 460                 const uint32_t major = msg.u.relayd_sock.major;
 461                 const uint32_t minor = msg.u.relayd_sock.minor;
 462                 const lttcomm_sock_proto protocol =
 463                         (enum lttcomm_sock_proto) msg.u.relayd_sock.relayd_socket_protocol;
 464
 465                 /* Session daemon status message are handled in the following call. */
 466                 consumer_add_relayd_socket(msg.u.relayd_sock.net_index,
 467                                            msg.u.relayd_sock.type,
 468                                            ctx,
 469                                            sock,
 470                                            consumer_sockpoll,
 471                                            msg.u.relayd_sock.session_id,
 472                                            msg.u.relayd_sock.relayd_session_id,
 473                                            major,
 474                                            minor,
 475                                            protocol);
 476                 goto end_nosignal;
 477         }
 478         case LTTNG_CONSUMER_ADD_CHANNEL:
 479         {
 480                 struct lttng_consumer_channel *new_channel;
 481                 int ret_send_status, ret_add_channel = 0;
 482                 const uint64_t chunk_id = msg.u.channel.chunk_id.value;
 483
 484                 health_code_update();
 485
 486                 /* First send a status message before receiving the fds. */
 487                 ret_send_status = consumer_send_status_msg(sock, ret_code);
 488                 if (ret_send_status < 0) {
 489                         /* Somehow, the session daemon is not responding anymore. */
 490                         goto error_fatal;
 491                 }
 492
 493                 health_code_update();
 494
 495                 DBG("consumer_add_channel %" PRIu64, msg.u.channel.channel_key);
 496                 new_channel = consumer_allocate_channel(msg.u.channel.channel_key,
 497                                                         msg.u.channel.session_id,
 498                                                         msg.u.channel.chunk_id.is_set ? &chunk_id :
 499                                                                                         nullptr,
 500                                                         msg.u.channel.pathname,
 501                                                         msg.u.channel.name,
 502                                                         msg.u.channel.relayd_id,
 503                                                         msg.u.channel.output,
 504                                                         msg.u.channel.tracefile_size,
 505                                                         msg.u.channel.tracefile_count,
 506                                                         0,
 507                                                         msg.u.channel.monitor,
 508                                                         msg.u.channel.live_timer_interval,
 509                                                         msg.u.channel.is_live,
 510                                                         nullptr,
 511                                                         nullptr);
 512                 if (new_channel == nullptr) {
 513                         lttng_consumer_send_error(ctx, LTTCOMM_CONSUMERD_OUTFD_ERROR);
 514                         goto end_nosignal;
 515                 }
 516                 new_channel->nb_init_stream_left = msg.u.channel.nb_init_streams;
 517                 switch (msg.u.channel.output) {
 518                 case LTTNG_EVENT_SPLICE:
 519                         new_channel->output = CONSUMER_CHANNEL_SPLICE;
 520                         break;
 521                 case LTTNG_EVENT_MMAP:
 522                         new_channel->output = CONSUMER_CHANNEL_MMAP;
 523                         break;
 524                 default:
 525                         ERR("Channel output unknown %d", msg.u.channel.output);
 526                         goto end_nosignal;
 527                 }
 528
 529                 /* Translate and save channel type. */
 530                 switch (msg.u.channel.type) {
 531                 case CONSUMER_CHANNEL_TYPE_DATA:
 532                 case CONSUMER_CHANNEL_TYPE_METADATA:
 533                         new_channel->type = (consumer_channel_type) msg.u.channel.type;
 534                         break;
 535                 default:
 536                         abort();
 537                         goto end_nosignal;
 538                 };
 539
 540                 health_code_update();
 541
 542                 if (ctx->on_recv_channel != nullptr) {
 543                         const int ret_recv_channel = ctx->on_recv_channel(new_channel);
 544                         if (ret_recv_channel == 0) {
 545                                 ret_add_channel = consumer_add_channel(new_channel, ctx);
 546                         } else if (ret_recv_channel < 0) {
 547                                 goto end_nosignal;
 548                         }
 549                 } else {
 550                         ret_add_channel = consumer_add_channel(new_channel, ctx);
 551                 }
 552                 if (msg.u.channel.type == CONSUMER_CHANNEL_TYPE_DATA && !ret_add_channel) {
 553                         int monitor_start_ret;
 554
 555                         DBG("Consumer starting monitor timer");
 556                         consumer_timer_live_start(new_channel, msg.u.channel.live_timer_interval);
 557                         monitor_start_ret = consumer_timer_monitor_start(
 558                                 new_channel, msg.u.channel.monitor_timer_interval);
 559                         if (monitor_start_ret < 0) {
 560                                 ERR("Starting channel monitoring timer failed");
 561                                 goto end_nosignal;
 562                         }
 563                 }
 564
 565                 health_code_update();
 566
 567                 /* If we received an error in add_channel, we need to report it. */
 568                 if (ret_add_channel < 0) {
 569                         ret_send_status = consumer_send_status_msg(sock, ret_add_channel);
 570                         if (ret_send_status < 0) {
 571                                 goto error_fatal;
 572                         }
 573                         goto end_nosignal;
 574                 }
 575
 576                 goto end_nosignal;
 577         }
 578         case LTTNG_CONSUMER_ADD_STREAM:
 579         {
 580                 int fd;
 581                 struct lttng_pipe *stream_pipe;
 582                 struct lttng_consumer_stream *new_stream;
 583                 struct lttng_consumer_channel *channel;
 584                 int alloc_ret = 0;
 585                 int ret_send_status, ret_poll, ret_get_max_subbuf_size;
 586                 ssize_t ret_pipe_write, ret_recv;
 587
 588                 /*
 589                  * Get stream's channel reference. Needed when adding the stream to the
 590                  * global hash table.
 591                  */
 592                 channel = consumer_find_channel(msg.u.stream.channel_key);
 593                 if (!channel) {
 594                         /*
 595                          * We could not find the channel. Can happen if cpu hotplug
 596                          * happens while tearing down.
 597                          */
 598                         ERR("Unable to find channel key %" PRIu64, msg.u.stream.channel_key);
 599                         ret_code = LTTCOMM_CONSUMERD_CHAN_NOT_FOUND;
 600                 }
 601
 602                 health_code_update();
 603
 604                 /* First send a status message before receiving the fds. */
 605                 ret_send_status = consumer_send_status_msg(sock, ret_code);
 606                 if (ret_send_status < 0) {
 607                         /* Somehow, the session daemon is not responding anymore. */
 608                         goto error_add_stream_fatal;
 609                 }
 610
 611                 health_code_update();
 612
 613                 if (ret_code != LTTCOMM_CONSUMERD_SUCCESS) {
 614                         /* Channel was not found. */
 615                         goto error_add_stream_nosignal;
 616                 }
 617
 618                 /* Blocking call */
 619                 health_poll_entry();
 620                 ret_poll = lttng_consumer_poll_socket(consumer_sockpoll);
 621                 health_poll_exit();
 622                 if (ret_poll) {
 623                         goto error_add_stream_fatal;
 624                 }
 625
 626                 health_code_update();
 627
 628                 /* Get stream file descriptor from socket */
 629                 ret_recv = lttcomm_recv_fds_unix_sock(sock, &fd, 1);
 630                 if (ret_recv != sizeof(fd)) {
 631                         lttng_consumer_send_error(ctx, LTTCOMM_CONSUMERD_ERROR_RECV_FD);
 632                         ret_func = ret_recv;
 633                         goto end;
 634                 }
 635
 636                 health_code_update();
 637
 638                 /*
 639                  * Send status code to session daemon only if the recv works. If the
 640                  * above recv() failed, the session daemon is notified through the
 641                  * error socket and the teardown is eventually done.
 642                  */
 643                 ret_send_status = consumer_send_status_msg(sock, ret_code);
 644                 if (ret_send_status < 0) {
 645                         /* Somehow, the session daemon is not responding anymore. */
 646                         goto error_add_stream_nosignal;
 647                 }
 648
 649                 health_code_update();
 650
 651                 pthread_mutex_lock(&channel->lock);
 652                 new_stream = consumer_stream_create(channel,
 653                                                     channel->key,
 654                                                     fd,
 655                                                     channel->name,
 656                                                     channel->relayd_id,
 657                                                     channel->session_id,
 658                                                     channel->trace_chunk,
 659                                                     msg.u.stream.cpu,
 660                                                     &alloc_ret,
 661                                                     channel->type,
 662                                                     channel->monitor);
 663                 if (new_stream == nullptr) {
 664                         switch (alloc_ret) {
 665                         case -ENOMEM:
 666                         case -EINVAL:
 667                         default:
 668                                 lttng_consumer_send_error(ctx, LTTCOMM_CONSUMERD_OUTFD_ERROR);
 669                                 break;
 670                         }
 671                         pthread_mutex_unlock(&channel->lock);
 672                         goto error_add_stream_nosignal;
 673                 }
 674
 675                 new_stream->wait_fd = fd;
 676                 ret_get_max_subbuf_size =
 677                         kernctl_get_max_subbuf_size(new_stream->wait_fd, &new_stream->max_sb_size);
 678                 if (ret_get_max_subbuf_size < 0) {
 679                         pthread_mutex_unlock(&channel->lock);
 680                         ERR("Failed to get kernel maximal subbuffer size");
 681                         goto error_add_stream_nosignal;
 682                 }
 683
 684                 consumer_stream_update_channel_attributes(new_stream, channel);
 685
 686                 /*
 687                  * We've just assigned the channel to the stream so increment the
 688                  * refcount right now. We don't need to increment the refcount for
 689                  * streams in no monitor because we handle manually the cleanup of
 690                  * those. It is very important to make sure there is NO prior
 691                  * consumer_del_stream() calls or else the refcount will be unbalanced.
 692                  */
 693                 if (channel->monitor) {
 694                         uatomic_inc(&new_stream->chan->refcount);
 695                 }
 696
 697                 /*
 698                  * The buffer flush is done on the session daemon side for the kernel
 699                  * so no need for the stream "hangup_flush_done" variable to be
 700                  * tracked. This is important for a kernel stream since we don't rely
 701                  * on the flush state of the stream to read data. It's not the case for
 702                  * user space tracing.
 703                  */
 704                 new_stream->hangup_flush_done = 0;
 705
 706                 health_code_update();
 707
 708                 pthread_mutex_lock(&new_stream->lock);
 709                 if (ctx->on_recv_stream) {
 710                         const int ret_recv_stream = ctx->on_recv_stream(new_stream);
 711                         if (ret_recv_stream < 0) {
 712                                 pthread_mutex_unlock(&new_stream->lock);
 713                                 pthread_mutex_unlock(&channel->lock);
 714                                 consumer_stream_free(new_stream);
 715                                 goto error_add_stream_nosignal;
 716                         }
 717                 }
 718                 health_code_update();
 719
 720                 if (new_stream->metadata_flag) {
 721                         channel->metadata_stream = new_stream;
 722                 }
 723
 724                 /* Do not monitor this stream. */
 725                 if (!channel->monitor) {
 726                         DBG("Kernel consumer add stream %s in no monitor mode with "
 727                             "relayd id %" PRIu64,
 728                             new_stream->name,
 729                             new_stream->net_seq_idx);
 730                         cds_list_add(&new_stream->send_node, &channel->streams.head);
 731                         pthread_mutex_unlock(&new_stream->lock);
 732                         pthread_mutex_unlock(&channel->lock);
 733                         goto end_add_stream;
 734                 }
 735
 736                 /* Send stream to relayd if the stream has an ID. */
 737                 if (new_stream->net_seq_idx != (uint64_t) -1ULL) {
 738                         int ret_send_relayd_stream;
 739
 740                         ret_send_relayd_stream =
 741                                 consumer_send_relayd_stream(new_stream, new_stream->chan->pathname);
 742                         if (ret_send_relayd_stream < 0) {
 743                                 pthread_mutex_unlock(&new_stream->lock);
 744                                 pthread_mutex_unlock(&channel->lock);
 745                                 consumer_stream_free(new_stream);
 746                                 goto error_add_stream_nosignal;
 747                         }
 748
 749                         /*
 750                          * If adding an extra stream to an already
 751                          * existing channel (e.g. cpu hotplug), we need
 752                          * to send the "streams_sent" command to relayd.
 753                          */
 754                         if (channel->streams_sent_to_relayd) {
 755                                 int ret_send_relayd_streams_sent;
 756
 757                                 ret_send_relayd_streams_sent =
 758                                         consumer_send_relayd_streams_sent(new_stream->net_seq_idx);
 759                                 if (ret_send_relayd_streams_sent < 0) {
 760                                         pthread_mutex_unlock(&new_stream->lock);
 761                                         pthread_mutex_unlock(&channel->lock);
 762                                         goto error_add_stream_nosignal;
 763                                 }
 764                         }
 765                 }
 766                 pthread_mutex_unlock(&new_stream->lock);
 767                 pthread_mutex_unlock(&channel->lock);
 768
 769                 /* Get the right pipe where the stream will be sent. */
 770                 if (new_stream->metadata_flag) {
 771                         consumer_add_metadata_stream(new_stream);
 772                         stream_pipe = ctx->consumer_metadata_pipe;
 773                 } else {
 774                         consumer_add_data_stream(new_stream);
 775                         stream_pipe = ctx->consumer_data_pipe;
 776                 }
 777
 778                 /* Visible to other threads */
 779                 new_stream->globally_visible = 1;
 780
 781                 health_code_update();
 782
 783                 ret_pipe_write =
 784                         lttng_pipe_write(stream_pipe, &new_stream, sizeof(new_stream)); /* NOLINT
 785                                                                                            sizeof
 786                                                                                            used on a
 787                                                                                            pointer.
 788                                                                                          */
 789                 if (ret_pipe_write < 0) {
 790                         ERR("Consumer write %s stream to pipe %d",
 791                             new_stream->metadata_flag ? "metadata" : "data",
 792                             lttng_pipe_get_writefd(stream_pipe));
 793                         if (new_stream->metadata_flag) {
 794                                 consumer_del_stream_for_metadata(new_stream);
 795                         } else {
 796                                 consumer_del_stream_for_data(new_stream);
 797                         }
 798                         goto error_add_stream_nosignal;
 799                 }
 800
 801                 DBG("Kernel consumer ADD_STREAM %s (fd: %d) %s with relayd id %" PRIu64,
 802                     new_stream->name,
 803                     fd,
 804                     new_stream->chan->pathname,
 805                     new_stream->relayd_stream_id);
 806         end_add_stream:
 807                 break;
 808         error_add_stream_nosignal:
 809                 goto end_nosignal;
 810         error_add_stream_fatal:
 811                 goto error_fatal;
 812         }
 813         case LTTNG_CONSUMER_STREAMS_SENT:
 814         {
 815                 struct lttng_consumer_channel *channel;
 816                 int ret_send_status;
 817
 818                 /*
 819                  * Get stream's channel reference. Needed when adding the stream to the
 820                  * global hash table.
 821                  */
 822                 channel = consumer_find_channel(msg.u.sent_streams.channel_key);
 823                 if (!channel) {
 824                         /*
 825                          * We could not find the channel. Can happen if cpu hotplug
 826                          * happens while tearing down.
 827                          */
 828                         ERR("Unable to find channel key %" PRIu64, msg.u.sent_streams.channel_key);
 829                         ret_code = LTTCOMM_CONSUMERD_CHAN_NOT_FOUND;
 830                 }
 831
 832                 health_code_update();
 833
 834                 /*
 835                  * Send status code to session daemon.
 836                  */
 837                 ret_send_status = consumer_send_status_msg(sock, ret_code);
 838                 if (ret_send_status < 0 || ret_code != LTTCOMM_CONSUMERD_SUCCESS) {
 839                         /* Somehow, the session daemon is not responding anymore. */
 840                         goto error_streams_sent_nosignal;
 841                 }
 842
 843                 health_code_update();
 844
 845                 /*
 846                  * We should not send this message if we don't monitor the
 847                  * streams in this channel.
 848                  */
 849                 if (!channel->monitor) {
 850                         goto end_error_streams_sent;
 851                 }
 852
 853                 health_code_update();
 854                 /* Send stream to relayd if the stream has an ID. */
 855                 if (msg.u.sent_streams.net_seq_idx != (uint64_t) -1ULL) {
 856                         int ret_send_relay_streams;
 857
 858                         ret_send_relay_streams =
 859                                 consumer_send_relayd_streams_sent(msg.u.sent_streams.net_seq_idx);
 860                         if (ret_send_relay_streams < 0) {
 861                                 goto error_streams_sent_nosignal;
 862                         }
 863                         channel->streams_sent_to_relayd = true;
 864                 }
 865         end_error_streams_sent:
 866                 break;
 867         error_streams_sent_nosignal:
 868                 goto end_nosignal;
 869         }
 870         case LTTNG_CONSUMER_UPDATE_STREAM:
 871         {
 872                 return -ENOSYS;
 873         }
 874         case LTTNG_CONSUMER_DESTROY_RELAYD:
 875         {
 876                 const uint64_t index = msg.u.destroy_relayd.net_seq_idx;
 877                 struct consumer_relayd_sock_pair *relayd;
 878                 int ret_send_status;
 879
 880                 DBG("Kernel consumer destroying relayd %" PRIu64, index);
 881
 882                 /* Get relayd reference if exists. */
 883                 relayd = consumer_find_relayd(index);
 884                 if (relayd == nullptr) {
 885                         DBG("Unable to find relayd %" PRIu64, index);
 886                         ret_code = LTTCOMM_CONSUMERD_RELAYD_FAIL;
 887                 }
 888
 889                 /*
 890                  * Each relayd socket pair has a refcount of stream attached to it
 891                  * which tells if the relayd is still active or not depending on the
 892                  * refcount value.
 893                  *
 894                  * This will set the destroy flag of the relayd object and destroy it
 895                  * if the refcount reaches zero when called.
 896                  *
 897                  * The destroy can happen either here or when a stream fd hangs up.
 898                  */
 899                 if (relayd) {
 900                         consumer_flag_relayd_for_destroy(relayd);
 901                 }
 902
 903                 health_code_update();
 904
 905                 ret_send_status = consumer_send_status_msg(sock, ret_code);
 906                 if (ret_send_status < 0) {
 907                         /* Somehow, the session daemon is not responding anymore. */
 908                         goto error_fatal;
 909                 }
 910
 911                 goto end_nosignal;
 912         }
 913         case LTTNG_CONSUMER_DATA_PENDING:
 914         {
 915                 int32_t ret_data_pending;
 916                 const uint64_t id = msg.u.data_pending.session_id;
 917                 ssize_t ret_send;
 918
 919                 DBG("Kernel consumer data pending command for id %" PRIu64, id);
 920
 921                 ret_data_pending = consumer_data_pending(id);
 922
 923                 health_code_update();
 924
 925                 /* Send back returned value to session daemon */
 926                 ret_send =
 927                         lttcomm_send_unix_sock(sock, &ret_data_pending, sizeof(ret_data_pending));
 928                 if (ret_send < 0) {
 929                         PERROR("send data pending ret code");
 930                         goto error_fatal;
 931                 }
 932
 933                 /*
 934                  * No need to send back a status message since the data pending
 935                  * returned value is the response.
 936                  */
 937                 break;
 938         }
 939         case LTTNG_CONSUMER_SNAPSHOT_CHANNEL:
 940         {
 941                 struct lttng_consumer_channel *channel;
 942                 const uint64_t key = msg.u.snapshot_channel.key;
 943                 int ret_send_status;
 944
 945                 channel = consumer_find_channel(key);
 946                 if (!channel) {
 947                         ERR("Channel %" PRIu64 " not found", key);
 948                         ret_code = LTTCOMM_CONSUMERD_CHAN_NOT_FOUND;
 949                 } else {
 950                         if (msg.u.snapshot_channel.metadata == 1) {
 951                                 int ret_snapshot;
 952
 953                                 ret_snapshot = lttng_kconsumer_snapshot_metadata(
 954                                         channel,
 955                                         key,
 956                                         msg.u.snapshot_channel.pathname,
 957                                         msg.u.snapshot_channel.relayd_id,
 958                                         ctx);
 959                                 if (ret_snapshot < 0) {
 960                                         ERR("Snapshot metadata failed");
 961                                         ret_code = LTTCOMM_CONSUMERD_SNAPSHOT_FAILED;
 962                                 }
 963                         } else {
 964                                 int ret_snapshot;
 965
 966                                 ret_snapshot = lttng_kconsumer_snapshot_channel(
 967                                         channel,
 968                                         key,
 969                                         msg.u.snapshot_channel.pathname,
 970                                         msg.u.snapshot_channel.relayd_id,
 971                                         msg.u.snapshot_channel.nb_packets_per_stream);
 972                                 if (ret_snapshot < 0) {
 973                                         ERR("Snapshot channel failed");
 974                                         ret_code = LTTCOMM_CONSUMERD_SNAPSHOT_FAILED;
 975                                 }
 976                         }
 977                 }
 978                 health_code_update();
 979
 980                 ret_send_status = consumer_send_status_msg(sock, ret_code);
 981                 if (ret_send_status < 0) {
 982                         /* Somehow, the session daemon is not responding anymore. */
 983                         goto end_nosignal;
 984                 }
 985                 break;
 986         }
 987         case LTTNG_CONSUMER_DESTROY_CHANNEL:
 988         {
 989                 const uint64_t key = msg.u.destroy_channel.key;
 990                 struct lttng_consumer_channel *channel;
 991                 int ret_send_status;
 992
 993                 channel = consumer_find_channel(key);
 994                 if (!channel) {
 995                         ERR("Kernel consumer destroy channel %" PRIu64 " not found", key);
 996                         ret_code = LTTCOMM_CONSUMERD_CHAN_NOT_FOUND;
 997                 }
 998
 999                 health_code_update();
1000
1001                 ret_send_status = consumer_send_status_msg(sock, ret_code);
1002                 if (ret_send_status < 0) {
1003                         /* Somehow, the session daemon is not responding anymore. */
1004                         goto end_destroy_channel;
1005                 }
1006
1007                 health_code_update();
1008
1009                 /* Stop right now if no channel was found. */
1010                 if (!channel) {
1011                         goto end_destroy_channel;
1012                 }
1013
1014                 /*
1015                  * This command should ONLY be issued for channel with streams set in
1016                  * no monitor mode.
1017                  */
1018                 LTTNG_ASSERT(!channel->monitor);
1019
1020                 /*
1021                  * The refcount should ALWAYS be 0 in the case of a channel in no
1022                  * monitor mode.
1023                  */
1024                 LTTNG_ASSERT(!uatomic_sub_return(&channel->refcount, 1));
1025
1026                 consumer_del_channel(channel);
1027         end_destroy_channel:
1028                 goto end_nosignal;
1029         }
1030         case LTTNG_CONSUMER_DISCARDED_EVENTS:
1031         {
1032                 ssize_t ret;
1033                 uint64_t count;
1034                 struct lttng_consumer_channel *channel;
1035                 const uint64_t id = msg.u.discarded_events.session_id;
1036                 const uint64_t key = msg.u.discarded_events.channel_key;
1037
1038                 DBG("Kernel consumer discarded events command for session id %" PRIu64
1039                     ", channel key %" PRIu64,
1040                     id,
1041                     key);
1042
1043                 channel = consumer_find_channel(key);
1044                 if (!channel) {
1045                         ERR("Kernel consumer discarded events channel %" PRIu64 " not found", key);
1046                         count = 0;
1047                 } else {
1048                         count = channel->discarded_events;
1049                 }
1050
1051                 health_code_update();
1052
1053                 /* Send back returned value to session daemon */
1054                 ret = lttcomm_send_unix_sock(sock, &count, sizeof(count));
1055                 if (ret < 0) {
1056                         PERROR("send discarded events");
1057                         goto error_fatal;
1058                 }
1059
1060                 break;
1061         }
1062         case LTTNG_CONSUMER_LOST_PACKETS:
1063         {
1064                 ssize_t ret;
1065                 uint64_t count;
1066                 struct lttng_consumer_channel *channel;
1067                 const uint64_t id = msg.u.lost_packets.session_id;
1068                 const uint64_t key = msg.u.lost_packets.channel_key;
1069
1070                 DBG("Kernel consumer lost packets command for session id %" PRIu64
1071                     ", channel key %" PRIu64,
1072                     id,
1073                     key);
1074
1075                 channel = consumer_find_channel(key);
1076                 if (!channel) {
1077                         ERR("Kernel consumer lost packets channel %" PRIu64 " not found", key);
1078                         count = 0;
1079                 } else {
1080                         count = channel->lost_packets;
1081                 }
1082
1083                 health_code_update();
1084
1085                 /* Send back returned value to session daemon */
1086                 ret = lttcomm_send_unix_sock(sock, &count, sizeof(count));
1087                 if (ret < 0) {
1088                         PERROR("send lost packets");
1089                         goto error_fatal;
1090                 }
1091
1092                 break;
1093         }
1094         case LTTNG_CONSUMER_SET_CHANNEL_MONITOR_PIPE:
1095         {
1096                 int channel_monitor_pipe;
1097                 int ret_send_status, ret_set_channel_monitor_pipe;
1098                 ssize_t ret_recv;
1099
1100                 ret_code = LTTCOMM_CONSUMERD_SUCCESS;
1101                 /* Successfully received the command's type. */
1102                 ret_send_status = consumer_send_status_msg(sock, ret_code);
1103                 if (ret_send_status < 0) {
1104                         goto error_fatal;
1105                 }
1106
1107                 ret_recv = lttcomm_recv_fds_unix_sock(sock, &channel_monitor_pipe, 1);
1108                 if (ret_recv != sizeof(channel_monitor_pipe)) {
1109                         ERR("Failed to receive channel monitor pipe");
1110                         goto error_fatal;
1111                 }
1112
1113                 DBG("Received channel monitor pipe (%d)", channel_monitor_pipe);
1114                 ret_set_channel_monitor_pipe =
1115                         consumer_timer_thread_set_channel_monitor_pipe(channel_monitor_pipe);
1116                 if (!ret_set_channel_monitor_pipe) {
1117                         int flags;
1118                         int ret_fcntl;
1119
1120                         ret_code = LTTCOMM_CONSUMERD_SUCCESS;
1121                         /* Set the pipe as non-blocking. */
1122                         ret_fcntl = fcntl(channel_monitor_pipe, F_GETFL, 0);
1123                         if (ret_fcntl == -1) {
1124                                 PERROR("fcntl get flags of the channel monitoring pipe");
1125                                 goto error_fatal;
1126                         }
1127                         flags = ret_fcntl;
1128
1129                         ret_fcntl = fcntl(channel_monitor_pipe, F_SETFL, flags | O_NONBLOCK);
1130                         if (ret_fcntl == -1) {
1131                                 PERROR("fcntl set O_NONBLOCK flag of the channel monitoring pipe");
1132                                 goto error_fatal;
1133                         }
1134                         DBG("Channel monitor pipe set as non-blocking");
1135                 } else {
1136                         ret_code = LTTCOMM_CONSUMERD_ALREADY_SET;
1137                 }
1138                 ret_send_status = consumer_send_status_msg(sock, ret_code);
1139                 if (ret_send_status < 0) {
1140                         goto error_fatal;
1141                 }
1142                 break;
1143         }
1144         case LTTNG_CONSUMER_ROTATE_CHANNEL:
1145         {
1146                 struct lttng_consumer_channel *channel;
1147                 const uint64_t key = msg.u.rotate_channel.key;
1148                 int ret_send_status;
1149
1150                 DBG("Consumer rotate channel %" PRIu64, key);
1151
1152                 channel = consumer_find_channel(key);
1153                 if (!channel) {
1154                         ERR("Channel %" PRIu64 " not found", key);
1155                         ret_code = LTTCOMM_CONSUMERD_CHAN_NOT_FOUND;
1156                 } else {
1157                         /*
1158                          * Sample the rotate position of all the streams in this channel.
1159                          */
1160                         int ret_rotate_channel;
1161
1162                         ret_rotate_channel = lttng_consumer_rotate_channel(
1163                                 channel, key, msg.u.rotate_channel.relayd_id);
1164                         if (ret_rotate_channel < 0) {
1165                                 ERR("Rotate channel failed");
1166                                 ret_code = LTTCOMM_CONSUMERD_ROTATION_FAIL;
1167                         }
1168
1169                         health_code_update();
1170                 }
1171
1172                 ret_send_status = consumer_send_status_msg(sock, ret_code);
1173                 if (ret_send_status < 0) {
1174                         /* Somehow, the session daemon is not responding anymore. */
1175                         goto error_rotate_channel;
1176                 }
1177                 if (channel) {
1178                         /* Rotate the streams that are ready right now. */
1179                         int ret_rotate;
1180
1181                         ret_rotate = lttng_consumer_rotate_ready_streams(channel, key);
1182                         if (ret_rotate < 0) {
1183                                 ERR("Rotate ready streams failed");
1184                         }
1185                 }
1186                 break;
1187         error_rotate_channel:
1188                 goto end_nosignal;
1189         }
1190         case LTTNG_CONSUMER_CLEAR_CHANNEL:
1191         {
1192                 struct lttng_consumer_channel *channel;
1193                 const uint64_t key = msg.u.clear_channel.key;
1194                 int ret_send_status;
1195
1196                 channel = consumer_find_channel(key);
1197                 if (!channel) {
1198                         DBG("Channel %" PRIu64 " not found", key);
1199                         ret_code = LTTCOMM_CONSUMERD_CHAN_NOT_FOUND;
1200                 } else {
1201                         int ret_clear_channel;
1202
1203                         ret_clear_channel = lttng_consumer_clear_channel(channel);
1204                         if (ret_clear_channel) {
1205                                 ERR("Clear channel failed");
1206                                 ret_code = (lttcomm_return_code) ret_clear_channel;
1207                         }
1208
1209                         health_code_update();
1210                 }
1211
1212                 ret_send_status = consumer_send_status_msg(sock, ret_code);
1213                 if (ret_send_status < 0) {
1214                         /* Somehow, the session daemon is not responding anymore. */
1215                         goto end_nosignal;
1216                 }
1217
1218                 break;
1219         }
1220         case LTTNG_CONSUMER_INIT:
1221         {
1222                 int ret_send_status;
1223                 lttng_uuid sessiond_uuid;
1224
1225                 std::copy(std::begin(msg.u.init.sessiond_uuid),
1226                           std::end(msg.u.init.sessiond_uuid),
1227                           sessiond_uuid.begin());
1228
1229                 ret_code = lttng_consumer_init_command(ctx, sessiond_uuid);
1230                 health_code_update();
1231                 ret_send_status = consumer_send_status_msg(sock, ret_code);
1232                 if (ret_send_status < 0) {
1233                         /* Somehow, the session daemon is not responding anymore. */
1234                         goto end_nosignal;
1235                 }
1236                 break;
1237         }
1238         case LTTNG_CONSUMER_CREATE_TRACE_CHUNK:
1239         {
1240                 const struct lttng_credentials credentials = {
1241                         .uid = LTTNG_OPTIONAL_INIT_VALUE(
1242                                 msg.u.create_trace_chunk.credentials.value.uid),
1243                         .gid = LTTNG_OPTIONAL_INIT_VALUE(
1244                                 msg.u.create_trace_chunk.credentials.value.gid),
1245                 };
1246                 const bool is_local_trace = !msg.u.create_trace_chunk.relayd_id.is_set;
1247                 const uint64_t relayd_id = msg.u.create_trace_chunk.relayd_id.value;
1248                 const char *chunk_override_name = *msg.u.create_trace_chunk.override_name ?
1249                         msg.u.create_trace_chunk.override_name :
1250                         nullptr;
1251                 struct lttng_directory_handle *chunk_directory_handle = nullptr;
1252
1253                 /*
1254                  * The session daemon will only provide a chunk directory file
1255                  * descriptor for local traces.
1256                  */
1257                 if (is_local_trace) {
1258                         int chunk_dirfd;
1259                         int ret_send_status;
1260                         ssize_t ret_recv;
1261
1262                         /* Acnowledge the reception of the command. */
1263                         ret_send_status = consumer_send_status_msg(sock, LTTCOMM_CONSUMERD_SUCCESS);
1264                         if (ret_send_status < 0) {
1265                                 /* Somehow, the session daemon is not responding anymore. */
1266                                 goto end_nosignal;
1267                         }
1268
1269                         ret_recv = lttcomm_recv_fds_unix_sock(sock, &chunk_dirfd, 1);
1270                         if (ret_recv != sizeof(chunk_dirfd)) {
1271                                 ERR("Failed to receive trace chunk directory file descriptor");
1272                                 goto error_fatal;
1273                         }
1274
1275                         DBG("Received trace chunk directory fd (%d)", chunk_dirfd);
1276                         chunk_directory_handle =
1277                                 lttng_directory_handle_create_from_dirfd(chunk_dirfd);
1278                         if (!chunk_directory_handle) {
1279                                 ERR("Failed to initialize chunk directory handle from directory file descriptor");
1280                                 if (close(chunk_dirfd)) {
1281                                         PERROR("Failed to close chunk directory file descriptor");
1282                                 }
1283                                 goto error_fatal;
1284                         }
1285                 }
1286
1287                 ret_code = lttng_consumer_create_trace_chunk(
1288                         !is_local_trace ? &relayd_id : nullptr,
1289                         msg.u.create_trace_chunk.session_id,
1290                         msg.u.create_trace_chunk.chunk_id,
1291                         (time_t) msg.u.create_trace_chunk.creation_timestamp,
1292                         chunk_override_name,
1293                         msg.u.create_trace_chunk.credentials.is_set ? &credentials : nullptr,
1294                         chunk_directory_handle);
1295                 lttng_directory_handle_put(chunk_directory_handle);
1296                 goto end_msg_sessiond;
1297         }
1298         case LTTNG_CONSUMER_CLOSE_TRACE_CHUNK:
1299         {
1300                 enum lttng_trace_chunk_command_type close_command =
1301                         (lttng_trace_chunk_command_type) msg.u.close_trace_chunk.close_command.value;
1302                 const uint64_t relayd_id = msg.u.close_trace_chunk.relayd_id.value;
1303                 struct lttcomm_consumer_close_trace_chunk_reply reply;
1304                 char path[LTTNG_PATH_MAX];
1305                 ssize_t ret_send;
1306
1307                 ret_code = lttng_consumer_close_trace_chunk(
1308                         msg.u.close_trace_chunk.relayd_id.is_set ? &relayd_id : nullptr,
1309                         msg.u.close_trace_chunk.session_id,
1310                         msg.u.close_trace_chunk.chunk_id,
1311                         (time_t) msg.u.close_trace_chunk.close_timestamp,
1312                         msg.u.close_trace_chunk.close_command.is_set ? &close_command : nullptr,
1313                         path);
1314                 reply.ret_code = ret_code;
1315                 reply.path_length = strlen(path) + 1;
1316                 ret_send = lttcomm_send_unix_sock(sock, &reply, sizeof(reply));
1317                 if (ret_send != sizeof(reply)) {
1318                         goto error_fatal;
1319                 }
1320                 ret_send = lttcomm_send_unix_sock(sock, path, reply.path_length);
1321                 if (ret_send != reply.path_length) {
1322                         goto error_fatal;
1323                 }
1324                 goto end_nosignal;
1325         }
1326         case LTTNG_CONSUMER_TRACE_CHUNK_EXISTS:
1327         {
1328                 const uint64_t relayd_id = msg.u.trace_chunk_exists.relayd_id.value;
1329
1330                 ret_code = lttng_consumer_trace_chunk_exists(
1331                         msg.u.trace_chunk_exists.relayd_id.is_set ? &relayd_id : nullptr,
1332                         msg.u.trace_chunk_exists.session_id,
1333                         msg.u.trace_chunk_exists.chunk_id);
1334                 goto end_msg_sessiond;
1335         }
1336         case LTTNG_CONSUMER_OPEN_CHANNEL_PACKETS:
1337         {
1338                 const uint64_t key = msg.u.open_channel_packets.key;
1339                 struct lttng_consumer_channel *channel = consumer_find_channel(key);
1340
1341                 if (channel) {
1342                         pthread_mutex_lock(&channel->lock);
1343                         ret_code = lttng_consumer_open_channel_packets(channel);
1344                         pthread_mutex_unlock(&channel->lock);
1345                 } else {
1346                         WARN("Channel %" PRIu64 " not found", key);
1347                         ret_code = LTTCOMM_CONSUMERD_CHAN_NOT_FOUND;
1348                 }
1349
1350                 health_code_update();
1351                 goto end_msg_sessiond;
1352         }
1353         default:
1354                 goto end_nosignal;
1355         }
1356
1357 end_nosignal:
1358         /*
1359          * Return 1 to indicate success since the 0 value can be a socket
1360          * shutdown during the recv() or send() call.
1361          */
1362         ret_func = 1;
1363         goto end;
1364 error_fatal:
1365         /* This will issue a consumer stop. */
1366         ret_func = -1;
1367         goto end;
1368 end_msg_sessiond:
1369         /*
1370          * The returned value here is not useful since either way we'll return 1 to
1371          * the caller because the session daemon socket management is done
1372          * elsewhere. Returning a negative code or 0 will shutdown the consumer.
1373          */
1374         {
1375                 int ret_send_status;
1376
1377                 ret_send_status = consumer_send_status_msg(sock, ret_code);
1378                 if (ret_send_status < 0) {
1379                         goto error_fatal;
1380                 }
1381         }
1382
1383         ret_func = 1;
1384
1385 end:
1386         health_code_update();
1387         return ret_func;
1388 }
1389
1390 /*
1391  * Sync metadata meaning request them to the session daemon and snapshot to the
1392  * metadata thread can consumer them.
1393  *
1394  * Metadata stream lock MUST be acquired.
1395  */
1396 enum sync_metadata_status lttng_kconsumer_sync_metadata(struct lttng_consumer_stream *metadata)
1397 {
1398         int ret;
1399         enum sync_metadata_status status;
1400
1401         LTTNG_ASSERT(metadata);
1402
1403         ret = kernctl_buffer_flush(metadata->wait_fd);
1404         if (ret < 0) {
1405                 ERR("Failed to flush kernel stream");
1406                 status = SYNC_METADATA_STATUS_ERROR;
1407                 goto end;
1408         }
1409
1410         ret = kernctl_snapshot(metadata->wait_fd);
1411         if (ret < 0) {
1412                 if (errno == EAGAIN) {
1413                         /* No new metadata, exit. */
1414                         DBG("Sync metadata, no new kernel metadata");
1415                         status = SYNC_METADATA_STATUS_NO_DATA;
1416                 } else {
1417                         ERR("Sync metadata, taking kernel snapshot failed.");
1418                         status = SYNC_METADATA_STATUS_ERROR;
1419                 }
1420         } else {
1421                 status = SYNC_METADATA_STATUS_NEW_DATA;
1422         }
1423
1424 end:
1425         return status;
1426 }
1427
1428 static int extract_common_subbuffer_info(struct lttng_consumer_stream *stream,
1429                                          struct stream_subbuffer *subbuf)
1430 {
1431         int ret;
1432
1433         ret = kernctl_get_subbuf_size(stream->wait_fd, &subbuf->info.data.subbuf_size);
1434         if (ret) {
1435                 goto end;
1436         }
1437
1438         ret = kernctl_get_padded_subbuf_size(stream->wait_fd,
1439                                              &subbuf->info.data.padded_subbuf_size);
1440         if (ret) {
1441                 goto end;
1442         }
1443
1444 end:
1445         return ret;
1446 }
1447
1448 static int extract_metadata_subbuffer_info(struct lttng_consumer_stream *stream,
1449                                            struct stream_subbuffer *subbuf)
1450 {
1451         int ret;
1452
1453         ret = extract_common_subbuffer_info(stream, subbuf);
1454         if (ret) {
1455                 goto end;
1456         }
1457
1458         ret = kernctl_get_metadata_version(stream->wait_fd, &subbuf->info.metadata.version);
1459         if (ret) {
1460                 goto end;
1461         }
1462
1463 end:
1464         return ret;
1465 }
1466
1467 static int extract_data_subbuffer_info(struct lttng_consumer_stream *stream,
1468                                        struct stream_subbuffer *subbuf)
1469 {
1470         int ret;
1471
1472         ret = extract_common_subbuffer_info(stream, subbuf);
1473         if (ret) {
1474                 goto end;
1475         }
1476
1477         ret = kernctl_get_packet_size(stream->wait_fd, &subbuf->info.data.packet_size);
1478         if (ret < 0) {
1479                 PERROR("Failed to get sub-buffer packet size");
1480                 goto end;
1481         }
1482
1483         ret = kernctl_get_content_size(stream->wait_fd, &subbuf->info.data.content_size);
1484         if (ret < 0) {
1485                 PERROR("Failed to get sub-buffer content size");
1486                 goto end;
1487         }
1488
1489         ret = kernctl_get_timestamp_begin(stream->wait_fd, &subbuf->info.data.timestamp_begin);
1490         if (ret < 0) {
1491                 PERROR("Failed to get sub-buffer begin timestamp");
1492                 goto end;
1493         }
1494
1495         ret = kernctl_get_timestamp_end(stream->wait_fd, &subbuf->info.data.timestamp_end);
1496         if (ret < 0) {
1497                 PERROR("Failed to get sub-buffer end timestamp");
1498                 goto end;
1499         }
1500
1501         ret = kernctl_get_events_discarded(stream->wait_fd, &subbuf->info.data.events_discarded);
1502         if (ret) {
1503                 PERROR("Failed to get sub-buffer events discarded count");
1504                 goto end;
1505         }
1506
1507         ret = kernctl_get_sequence_number(stream->wait_fd,
1508                                           &subbuf->info.data.sequence_number.value);
1509         if (ret) {
1510                 /* May not be supported by older LTTng-modules. */
1511                 if (ret != -ENOTTY) {
1512                         PERROR("Failed to get sub-buffer sequence number");
1513                         goto end;
1514                 }
1515         } else {
1516                 subbuf->info.data.sequence_number.is_set = true;
1517         }
1518
1519         ret = kernctl_get_stream_id(stream->wait_fd, &subbuf->info.data.stream_id);
1520         if (ret < 0) {
1521                 PERROR("Failed to get stream id");
1522                 goto end;
1523         }
1524
1525         ret = kernctl_get_instance_id(stream->wait_fd, &subbuf->info.data.stream_instance_id.value);
1526         if (ret) {
1527                 /* May not be supported by older LTTng-modules. */
1528                 if (ret != -ENOTTY) {
1529                         PERROR("Failed to get stream instance id");
1530                         goto end;
1531                 }
1532         } else {
1533                 subbuf->info.data.stream_instance_id.is_set = true;
1534         }
1535 end:
1536         return ret;
1537 }
1538
1539 static enum get_next_subbuffer_status get_subbuffer_common(struct lttng_consumer_stream *stream,
1540                                                            struct stream_subbuffer *subbuffer)
1541 {
1542         int ret;
1543         enum get_next_subbuffer_status status;
1544
1545         ret = kernctl_get_next_subbuf(stream->wait_fd);
1546         switch (ret) {
1547         case 0:
1548                 status = GET_NEXT_SUBBUFFER_STATUS_OK;
1549                 break;
1550         case -ENODATA:
1551         case -EAGAIN:
1552                 /*
1553                  * The caller only expects -ENODATA when there is no data to
1554                  * read, but the kernel tracer returns -EAGAIN when there is
1555                  * currently no data for a non-finalized stream, and -ENODATA
1556                  * when there is no data for a finalized stream. Those can be
1557                  * combined into a -ENODATA return value.
1558                  */
1559                 status = GET_NEXT_SUBBUFFER_STATUS_NO_DATA;
1560                 goto end;
1561         default:
1562                 status = GET_NEXT_SUBBUFFER_STATUS_ERROR;
1563                 goto end;
1564         }
1565
1566         ret = stream->read_subbuffer_ops.extract_subbuffer_info(stream, subbuffer);
1567         if (ret) {
1568                 status = GET_NEXT_SUBBUFFER_STATUS_ERROR;
1569         }
1570 end:
1571         return status;
1572 }
1573
1574 static enum get_next_subbuffer_status
1575 get_next_subbuffer_splice(struct lttng_consumer_stream *stream, struct stream_subbuffer *subbuffer)
1576 {
1577         const enum get_next_subbuffer_status status = get_subbuffer_common(stream, subbuffer);
1578
1579         if (status != GET_NEXT_SUBBUFFER_STATUS_OK) {
1580                 goto end;
1581         }
1582
1583         subbuffer->buffer.fd = stream->wait_fd;
1584 end:
1585         return status;
1586 }
1587
1588 static enum get_next_subbuffer_status get_next_subbuffer_mmap(struct lttng_consumer_stream *stream,
1589                                                               struct stream_subbuffer *subbuffer)
1590 {
1591         int ret;
1592         enum get_next_subbuffer_status status;
1593         const char *addr;
1594
1595         status = get_subbuffer_common(stream, subbuffer);
1596         if (status != GET_NEXT_SUBBUFFER_STATUS_OK) {
1597                 goto end;
1598         }
1599
1600         ret = get_current_subbuf_addr(stream, &addr);
1601         if (ret) {
1602                 status = GET_NEXT_SUBBUFFER_STATUS_ERROR;
1603                 goto end;
1604         }
1605
1606         subbuffer->buffer.buffer =
1607                 lttng_buffer_view_init(addr, 0, subbuffer->info.data.padded_subbuf_size);
1608 end:
1609         return status;
1610 }
1611
1612 static enum get_next_subbuffer_status
1613 get_next_subbuffer_metadata_check(struct lttng_consumer_stream *stream,
1614                                   struct stream_subbuffer *subbuffer)
1615 {
1616         int ret;
1617         const char *addr;
1618         bool coherent;
1619         enum get_next_subbuffer_status status;
1620
1621         ret = kernctl_get_next_subbuf_metadata_check(stream->wait_fd, &coherent);
1622         if (ret) {
1623                 goto end;
1624         }
1625
1626         ret = stream->read_subbuffer_ops.extract_subbuffer_info(stream, subbuffer);
1627         if (ret) {
1628                 goto end;
1629         }
1630
1631         LTTNG_OPTIONAL_SET(&subbuffer->info.metadata.coherent, coherent);
1632
1633         ret = get_current_subbuf_addr(stream, &addr);
1634         if (ret) {
1635                 goto end;
1636         }
1637
1638         subbuffer->buffer.buffer =
1639                 lttng_buffer_view_init(addr, 0, subbuffer->info.data.padded_subbuf_size);
1640         DBG("Got metadata packet with padded_subbuf_size = %lu, coherent = %s",
1641             subbuffer->info.metadata.padded_subbuf_size,
1642             coherent ? "true" : "false");
1643 end:
1644         /*
1645          * The caller only expects -ENODATA when there is no data to read, but
1646          * the kernel tracer returns -EAGAIN when there is currently no data
1647          * for a non-finalized stream, and -ENODATA when there is no data for a
1648          * finalized stream. Those can be combined into a -ENODATA return value.
1649          */
1650         switch (ret) {
1651         case 0:
1652                 status = GET_NEXT_SUBBUFFER_STATUS_OK;
1653                 break;
1654         case -ENODATA:
1655         case -EAGAIN:
1656                 /*
1657                  * The caller only expects -ENODATA when there is no data to
1658                  * read, but the kernel tracer returns -EAGAIN when there is
1659                  * currently no data for a non-finalized stream, and -ENODATA
1660                  * when there is no data for a finalized stream. Those can be
1661                  * combined into a -ENODATA return value.
1662                  */
1663                 status = GET_NEXT_SUBBUFFER_STATUS_NO_DATA;
1664                 break;
1665         default:
1666                 status = GET_NEXT_SUBBUFFER_STATUS_ERROR;
1667                 break;
1668         }
1669
1670         return status;
1671 }
1672
1673 static int put_next_subbuffer(struct lttng_consumer_stream *stream,
1674                               struct stream_subbuffer *subbuffer __attribute__((unused)))
1675 {
1676         const int ret = kernctl_put_next_subbuf(stream->wait_fd);
1677
1678         if (ret) {
1679                 if (ret == -EFAULT) {
1680                         PERROR("Error in unreserving sub buffer");
1681                 } else if (ret == -EIO) {
1682                         /* Should never happen with newer LTTng versions */
1683                         PERROR("Reader has been pushed by the writer, last sub-buffer corrupted");
1684                 }
1685         }
1686
1687         return ret;
1688 }
1689
1690 static bool is_get_next_check_metadata_available(int tracer_fd)
1691 {
1692         const int ret = kernctl_get_next_subbuf_metadata_check(tracer_fd, nullptr);
1693         const bool available = ret != -ENOTTY;
1694
1695         if (ret == 0) {
1696                 /* get succeeded, make sure to put the subbuffer. */
1697                 kernctl_put_subbuf(tracer_fd);
1698         }
1699
1700         return available;
1701 }
1702
1703 static int signal_metadata(struct lttng_consumer_stream *stream,
1704                            struct lttng_consumer_local_data *ctx __attribute__((unused)))
1705 {
1706         ASSERT_LOCKED(stream->metadata_rdv_lock);
1707         return pthread_cond_broadcast(&stream->metadata_rdv) ? -errno : 0;
1708 }
1709
1710 static int lttng_kconsumer_set_stream_ops(struct lttng_consumer_stream *stream)
1711 {
1712         int ret = 0;
1713
1714         if (stream->metadata_flag && stream->chan->is_live) {
1715                 DBG("Attempting to enable metadata bucketization for live consumers");
1716                 if (is_get_next_check_metadata_available(stream->wait_fd)) {
1717                         DBG("Kernel tracer supports get_next_subbuffer_metadata_check, metadata will be accumulated until a coherent state is reached");
1718                         stream->read_subbuffer_ops.get_next_subbuffer =
1719                                 get_next_subbuffer_metadata_check;
1720                         ret = consumer_stream_enable_metadata_bucketization(stream);
1721                         if (ret) {
1722                                 goto end;
1723                         }
1724                 } else {
1725                         /*
1726                          * The kernel tracer version is too old to indicate
1727                          * when the metadata stream has reached a "coherent"
1728                          * (parseable) point.
1729                          *
1730                          * This means that a live viewer may see an incoherent
1731                          * sequence of metadata and fail to parse it.
1732                          */
1733                         WARN("Kernel tracer does not support get_next_subbuffer_metadata_check which may cause live clients to fail to parse the metadata stream");
1734                         metadata_bucket_destroy(stream->metadata_bucket);
1735                         stream->metadata_bucket = nullptr;
1736                 }
1737
1738                 stream->read_subbuffer_ops.on_sleep = signal_metadata;
1739         }
1740
1741         if (!stream->read_subbuffer_ops.get_next_subbuffer) {
1742                 if (stream->chan->output == CONSUMER_CHANNEL_MMAP) {
1743                         stream->read_subbuffer_ops.get_next_subbuffer = get_next_subbuffer_mmap;
1744                 } else {
1745                         stream->read_subbuffer_ops.get_next_subbuffer = get_next_subbuffer_splice;
1746                 }
1747         }
1748
1749         if (stream->metadata_flag) {
1750                 stream->read_subbuffer_ops.extract_subbuffer_info = extract_metadata_subbuffer_info;
1751         } else {
1752                 stream->read_subbuffer_ops.extract_subbuffer_info = extract_data_subbuffer_info;
1753                 if (stream->chan->is_live) {
1754                         stream->read_subbuffer_ops.send_live_beacon = consumer_flush_kernel_index;
1755                 }
1756         }
1757
1758         stream->read_subbuffer_ops.put_next_subbuffer = put_next_subbuffer;
1759 end:
1760         return ret;
1761 }
1762
1763 int lttng_kconsumer_on_recv_stream(struct lttng_consumer_stream *stream)
1764 {
1765         int ret;
1766
1767         LTTNG_ASSERT(stream);
1768
1769         /*
1770          * Don't create anything if this is set for streaming or if there is
1771          * no current trace chunk on the parent channel.
1772          */
1773         if (stream->net_seq_idx == (uint64_t) -1ULL && stream->chan->monitor &&
1774             stream->chan->trace_chunk) {
1775                 ret = consumer_stream_create_output_files(stream, true);
1776                 if (ret) {
1777                         goto error;
1778                 }
1779         }
1780
1781         if (stream->output == LTTNG_EVENT_MMAP) {
1782                 /* get the len of the mmap region */
1783                 unsigned long mmap_len;
1784
1785                 ret = kernctl_get_mmap_len(stream->wait_fd, &mmap_len);
1786                 if (ret != 0) {
1787                         PERROR("kernctl_get_mmap_len");
1788                         goto error_close_fd;
1789                 }
1790                 stream->mmap_len = (size_t) mmap_len;
1791
1792                 stream->mmap_base =
1793                         mmap(nullptr, stream->mmap_len, PROT_READ, MAP_PRIVATE, stream->wait_fd, 0);
1794                 if (stream->mmap_base == MAP_FAILED) {
1795                         PERROR("Error mmaping");
1796                         ret = -1;
1797                         goto error_close_fd;
1798                 }
1799         }
1800
1801         ret = lttng_kconsumer_set_stream_ops(stream);
1802         if (ret) {
1803                 goto error_close_fd;
1804         }
1805
1806         /* we return 0 to let the library handle the FD internally */
1807         return 0;
1808
1809 error_close_fd:
1810         if (stream->out_fd >= 0) {
1811                 int err;
1812
1813                 err = close(stream->out_fd);
1814                 LTTNG_ASSERT(!err);
1815                 stream->out_fd = -1;
1816         }
1817 error:
1818         return ret;
1819 }
1820
1821 /*
1822  * Check if data is still being extracted from the buffers for a specific
1823  * stream. Consumer data lock MUST be acquired before calling this function
1824  * and the stream lock.
1825  *
1826  * Return 1 if the traced data are still getting read else 0 meaning that the
1827  * data is available for trace viewer reading.
1828  */
1829 int lttng_kconsumer_data_pending(struct lttng_consumer_stream *stream)
1830 {
1831         int ret;
1832
1833         LTTNG_ASSERT(stream);
1834
1835         if (stream->endpoint_status != CONSUMER_ENDPOINT_ACTIVE) {
1836                 ret = 0;
1837                 goto end;
1838         }
1839
1840         ret = kernctl_get_next_subbuf(stream->wait_fd);
1841         if (ret == 0) {
1842                 /* There is still data so let's put back this subbuffer. */
1843                 ret = kernctl_put_subbuf(stream->wait_fd);
1844                 LTTNG_ASSERT(ret == 0);
1845                 ret = 1; /* Data is pending */
1846                 goto end;
1847         }
1848
1849         /* Data is NOT pending and ready to be read. */
1850         ret = 0;
1851
1852 end:
1853         return ret;
1854 }