src/common/kernel-consumer/kernel-consumer.c

   1 /*
   2  * Copyright (C) 2011 - Julien Desfossez <julien.desfossez@polymtl.ca>
   3  *                      Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License, version 2 only,
   7  * as published by the Free Software Foundation.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License along
  15  * with this program; if not, write to the Free Software Foundation, Inc.,
  16  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  17  */
  18
  19 #define _LGPL_SOURCE
  20 #include <assert.h>
  21 #include <poll.h>
  22 #include <pthread.h>
  23 #include <stdlib.h>
  24 #include <string.h>
  25 #include <sys/mman.h>
  26 #include <sys/socket.h>
  27 #include <sys/types.h>
  28 #include <inttypes.h>
  29 #include <unistd.h>
  30 #include <sys/stat.h>
  31
  32 #include <bin/lttng-consumerd/health-consumerd.h>
  33 #include <common/common.h>
  34 #include <common/kernel-ctl/kernel-ctl.h>
  35 #include <common/sessiond-comm/sessiond-comm.h>
  36 #include <common/sessiond-comm/relayd.h>
  37 #include <common/compat/fcntl.h>
  38 #include <common/compat/endian.h>
  39 #include <common/pipe.h>
  40 #include <common/relayd/relayd.h>
  41 #include <common/utils.h>
  42 #include <common/consumer/consumer-stream.h>
  43 #include <common/index/index.h>
  44 #include <common/consumer/consumer-timer.h>
  45 #include <common/optional.h>
  46 #include <common/buffer-view.h>
  47 #include <common/consumer/consumer.h>
  48 #include <stdint.h>
  49
  50 #include "kernel-consumer.h"
  51
  52 extern struct lttng_consumer_global_data consumer_data;
  53 extern int consumer_poll_timeout;
  54 extern volatile int consumer_quit;
  55
  56 /*
  57  * Take a snapshot for a specific fd
  58  *
  59  * Returns 0 on success, < 0 on error
  60  */
  61 int lttng_kconsumer_take_snapshot(struct lttng_consumer_stream *stream)
  62 {
  63         int ret = 0;
  64         int infd = stream->wait_fd;
  65
  66         ret = kernctl_snapshot(infd);
  67         /*
  68          * -EAGAIN is not an error, it just means that there is no data to
  69          *  be read.
  70          */
  71         if (ret != 0 && ret != -EAGAIN) {
  72                 PERROR("Getting sub-buffer snapshot.");
  73         }
  74
  75         return ret;
  76 }
  77
  78 /*
  79  * Get the produced position
  80  *
  81  * Returns 0 on success, < 0 on error
  82  */
  83 int lttng_kconsumer_get_produced_snapshot(struct lttng_consumer_stream *stream,
  84                 unsigned long *pos)
  85 {
  86         int ret;
  87         int infd = stream->wait_fd;
  88
  89         ret = kernctl_snapshot_get_produced(infd, pos);
  90         if (ret != 0) {
  91                 PERROR("kernctl_snapshot_get_produced");
  92         }
  93
  94         return ret;
  95 }
  96
  97 /*
  98  * Get the consumerd position
  99  *
 100  * Returns 0 on success, < 0 on error
 101  */
 102 int lttng_kconsumer_get_consumed_snapshot(struct lttng_consumer_stream *stream,
 103                 unsigned long *pos)
 104 {
 105         int ret;
 106         int infd = stream->wait_fd;
 107
 108         ret = kernctl_snapshot_get_consumed(infd, pos);
 109         if (ret != 0) {
 110                 PERROR("kernctl_snapshot_get_consumed");
 111         }
 112
 113         return ret;
 114 }
 115
 116 static
 117 int get_current_subbuf_addr(struct lttng_consumer_stream *stream,
 118                 const char **addr)
 119 {
 120         int ret;
 121         unsigned long mmap_offset;
 122         const char *mmap_base = stream->mmap_base;
 123
 124         ret = kernctl_get_mmap_read_offset(stream->wait_fd, &mmap_offset);
 125         if (ret < 0) {
 126                 PERROR("Failed to get mmap read offset");
 127                 goto error;
 128         }
 129
 130         *addr = mmap_base + mmap_offset;
 131 error:
 132         return ret;
 133 }
 134
 135 /*
 136  * Take a snapshot of all the stream of a channel
 137  *
 138  * Returns 0 on success, < 0 on error
 139  */
 140 int lttng_kconsumer_snapshot_channel(uint64_t key, char *path,
 141                 uint64_t relayd_id, uint64_t nb_packets_per_stream,
 142                 struct lttng_consumer_local_data *ctx)
 143 {
 144         int ret;
 145         struct lttng_consumer_channel *channel;
 146         struct lttng_consumer_stream *stream;
 147
 148         DBG("Kernel consumer snapshot channel %" PRIu64, key);
 149
 150         rcu_read_lock();
 151
 152         channel = consumer_find_channel(key);
 153         if (!channel) {
 154                 ERR("No channel found for key %" PRIu64, key);
 155                 ret = -1;
 156                 goto end;
 157         }
 158
 159         /* Splice is not supported yet for channel snapshot. */
 160         if (channel->output != CONSUMER_CHANNEL_MMAP) {
 161                 ERR("Unsupported output %d", channel->output);
 162                 ret = -1;
 163                 goto end;
 164         }
 165
 166         cds_list_for_each_entry(stream, &channel->streams.head, send_node) {
 167                 unsigned long consumed_pos, produced_pos;
 168
 169                 health_code_update();
 170
 171                 /*
 172                  * Lock stream because we are about to change its state.
 173                  */
 174                 pthread_mutex_lock(&stream->lock);
 175
 176                 /*
 177                  * Assign the received relayd ID so we can use it for streaming. The streams
 178                  * are not visible to anyone so this is OK to change it.
 179                  */
 180                 stream->relayd_id = relayd_id;
 181                 channel->relayd_id = relayd_id;
 182                 if (relayd_id != (uint64_t) -1ULL) {
 183                         ret = consumer_send_relayd_stream(stream, path);
 184                         if (ret < 0) {
 185                                 ERR("sending stream to relayd");
 186                                 goto end_unlock;
 187                         }
 188                 } else {
 189                         ret = utils_create_stream_file(path, stream->name,
 190                                         stream->chan->tracefile_size,
 191                                         stream->tracefile_count_current,
 192                                         stream->uid, stream->gid, NULL);
 193                         if (ret < 0) {
 194                                 ERR("utils_create_stream_file");
 195                                 goto end_unlock;
 196                         }
 197
 198                         stream->out_fd = ret;
 199                         stream->tracefile_size_current = 0;
 200
 201                         DBG("Kernel consumer snapshot stream %s/%s (%" PRIu64 ")",
 202                                         path, stream->name, stream->key);
 203                 }
 204                 if (relayd_id != -1ULL) {
 205                         ret = consumer_send_relayd_streams_sent(relayd_id);
 206                         if (ret < 0) {
 207                                 ERR("sending streams sent to relayd");
 208                                 goto end_unlock;
 209                         }
 210                         channel->streams_sent_to_relayd = true;
 211                 }
 212
 213                 ret = kernctl_buffer_flush_empty(stream->wait_fd);
 214                 if (ret < 0) {
 215                         /*
 216                          * Doing a buffer flush which does not take into
 217                          * account empty packets. This is not perfect
 218                          * for stream intersection, but required as a
 219                          * fall-back when "flush_empty" is not
 220                          * implemented by lttng-modules.
 221                          */
 222                         ret = kernctl_buffer_flush(stream->wait_fd);
 223                         if (ret < 0) {
 224                                 ERR("Failed to flush kernel stream");
 225                                 goto end_unlock;
 226                         }
 227                         goto end_unlock;
 228                 }
 229
 230                 ret = lttng_kconsumer_take_snapshot(stream);
 231                 if (ret < 0) {
 232                         ERR("Taking kernel snapshot");
 233                         goto end_unlock;
 234                 }
 235
 236                 ret = lttng_kconsumer_get_produced_snapshot(stream, &produced_pos);
 237                 if (ret < 0) {
 238                         ERR("Produced kernel snapshot position");
 239                         goto end_unlock;
 240                 }
 241
 242                 ret = lttng_kconsumer_get_consumed_snapshot(stream, &consumed_pos);
 243                 if (ret < 0) {
 244                         ERR("Consumerd kernel snapshot position");
 245                         goto end_unlock;
 246                 }
 247
 248                 if (stream->max_sb_size == 0) {
 249                         ret = kernctl_get_max_subbuf_size(stream->wait_fd,
 250                                         &stream->max_sb_size);
 251                         if (ret < 0) {
 252                                 ERR("Getting kernel max_sb_size");
 253                                 goto end_unlock;
 254                         }
 255                 }
 256
 257                 consumed_pos = consumer_get_consume_start_pos(consumed_pos,
 258                                 produced_pos, nb_packets_per_stream,
 259                                 stream->max_sb_size);
 260
 261                 while (consumed_pos < produced_pos) {
 262                         ssize_t read_len;
 263                         unsigned long len, padded_len;
 264                         const char *subbuf_addr;
 265                         struct lttng_buffer_view subbuf_view;
 266
 267                         health_code_update();
 268                         DBG("Kernel consumer taking snapshot at pos %lu", consumed_pos);
 269
 270                         ret = kernctl_get_subbuf(stream->wait_fd, &consumed_pos);
 271                         if (ret < 0) {
 272                                 if (ret != -EAGAIN) {
 273                                         PERROR("kernctl_get_subbuf snapshot");
 274                                         goto end_unlock;
 275                                 }
 276                                 DBG("Kernel consumer get subbuf failed. Skipping it.");
 277                                 consumed_pos += stream->max_sb_size;
 278                                 stream->chan->lost_packets++;
 279                                 continue;
 280                         }
 281
 282                         ret = kernctl_get_subbuf_size(stream->wait_fd, &len);
 283                         if (ret < 0) {
 284                                 ERR("Snapshot kernctl_get_subbuf_size");
 285                                 goto error_put_subbuf;
 286                         }
 287
 288                         ret = kernctl_get_padded_subbuf_size(stream->wait_fd, &padded_len);
 289                         if (ret < 0) {
 290                                 ERR("Snapshot kernctl_get_padded_subbuf_size");
 291                                 goto error_put_subbuf;
 292                         }
 293
 294                         ret = get_current_subbuf_addr(stream, &subbuf_addr);
 295                         if (ret) {
 296                                 goto error_put_subbuf;
 297                         }
 298
 299                         subbuf_view = lttng_buffer_view_init(
 300                                         subbuf_addr, 0, padded_len);
 301                         read_len = lttng_consumer_on_read_subbuffer_mmap(ctx,
 302                                         stream, &subbuf_view,
 303                                         padded_len - len);
 304                         /*
 305                          * We write the padded len in local tracefiles but the data len
 306                          * when using a relay. Display the error but continue processing
 307                          * to try to release the subbuffer.
 308                          */
 309                         if (relayd_id != (uint64_t) -1ULL) {
 310                                 if (read_len != len) {
 311                                         ERR("Error sending to the relay (ret: %zd != len: %lu)",
 312                                                         read_len, len);
 313                                 }
 314                         } else {
 315                                 if (read_len != padded_len) {
 316                                         ERR("Error writing to tracefile (ret: %zd != len: %lu)",
 317                                                         read_len, padded_len);
 318                                 }
 319                         }
 320
 321                         ret = kernctl_put_subbuf(stream->wait_fd);
 322                         if (ret < 0) {
 323                                 ERR("Snapshot kernctl_put_subbuf");
 324                                 goto end_unlock;
 325                         }
 326                         consumed_pos += stream->max_sb_size;
 327                 }
 328
 329                 if (relayd_id == (uint64_t) -1ULL) {
 330                         if (stream->out_fd >= 0) {
 331                                 ret = close(stream->out_fd);
 332                                 if (ret < 0) {
 333                                         PERROR("Kernel consumer snapshot close out_fd");
 334                                         goto end_unlock;
 335                                 }
 336                                 stream->out_fd = -1;
 337                         }
 338                 } else {
 339                         close_relayd_stream(stream);
 340                         stream->relayd_id = (uint64_t) -1ULL;
 341                 }
 342                 pthread_mutex_unlock(&stream->lock);
 343         }
 344
 345         /* All good! */
 346         ret = 0;
 347         goto end;
 348
 349 error_put_subbuf:
 350         ret = kernctl_put_subbuf(stream->wait_fd);
 351         if (ret < 0) {
 352                 ERR("Snapshot kernctl_put_subbuf error path");
 353         }
 354 end_unlock:
 355         pthread_mutex_unlock(&stream->lock);
 356 end:
 357         rcu_read_unlock();
 358         return ret;
 359 }
 360
 361 /*
 362  * Read the whole metadata available for a snapshot.
 363  *
 364  * Returns 0 on success, < 0 on error
 365  */
 366 static int lttng_kconsumer_snapshot_metadata(uint64_t key, char *path,
 367                 uint64_t relayd_id, struct lttng_consumer_local_data *ctx)
 368 {
 369         int ret, use_relayd = 0;
 370         ssize_t ret_read;
 371         struct lttng_consumer_channel *metadata_channel;
 372         struct lttng_consumer_stream *metadata_stream;
 373
 374         assert(ctx);
 375
 376         DBG("Kernel consumer snapshot metadata with key %" PRIu64 " at path %s",
 377                         key, path);
 378
 379         rcu_read_lock();
 380
 381         metadata_channel = consumer_find_channel(key);
 382         if (!metadata_channel) {
 383                 ERR("Kernel snapshot metadata not found for key %" PRIu64, key);
 384                 ret = -1;
 385                 goto error_no_channel;
 386         }
 387
 388         metadata_stream = metadata_channel->metadata_stream;
 389         assert(metadata_stream);
 390         pthread_mutex_lock(&metadata_stream->lock);
 391
 392         /* Flag once that we have a valid relayd for the stream. */
 393         if (relayd_id != (uint64_t) -1ULL) {
 394                 use_relayd = 1;
 395         }
 396
 397         if (use_relayd) {
 398                 ret = consumer_send_relayd_stream(metadata_stream, path);
 399                 if (ret < 0) {
 400                         goto error_snapshot;
 401                 }
 402         } else {
 403                 ret = utils_create_stream_file(path, metadata_stream->name,
 404                                 metadata_stream->chan->tracefile_size,
 405                                 metadata_stream->tracefile_count_current,
 406                                 metadata_stream->uid, metadata_stream->gid, NULL);
 407                 if (ret < 0) {
 408                         goto error_snapshot;
 409                 }
 410                 metadata_stream->out_fd = ret;
 411         }
 412
 413         do {
 414                 health_code_update();
 415
 416                 ret_read = lttng_consumer_read_subbuffer(metadata_stream, ctx, true);
 417                 if (ret_read < 0) {
 418                         if (ret_read != -EAGAIN) {
 419                                 ERR("Kernel snapshot reading metadata subbuffer (ret: %zd)",
 420                                                 ret_read);
 421                                 ret = ret_read;
 422                                 goto error_snapshot;
 423                         }
 424                         /* ret_read is negative at this point so we will exit the loop. */
 425                         continue;
 426                 }
 427         } while (ret_read >= 0);
 428
 429         if (use_relayd) {
 430                 close_relayd_stream(metadata_stream);
 431                 metadata_stream->relayd_id = (uint64_t) -1ULL;
 432         } else {
 433                 if (metadata_stream->out_fd >= 0) {
 434                         ret = close(metadata_stream->out_fd);
 435                         if (ret < 0) {
 436                                 PERROR("Kernel consumer snapshot metadata close out_fd");
 437                                 /*
 438                                  * Don't go on error here since the snapshot was successful at this
 439                                  * point but somehow the close failed.
 440                                  */
 441                         }
 442                         metadata_stream->out_fd = -1;
 443                 }
 444         }
 445
 446         ret = 0;
 447 error_snapshot:
 448         pthread_mutex_unlock(&metadata_stream->lock);
 449         cds_list_del(&metadata_stream->send_node);
 450         consumer_stream_destroy(metadata_stream, NULL);
 451         metadata_channel->metadata_stream = NULL;
 452 error_no_channel:
 453         rcu_read_unlock();
 454         return ret;
 455 }
 456
 457 /*
 458  * Receive command from session daemon and process it.
 459  *
 460  * Return 1 on success else a negative value or 0.
 461  */
 462 int lttng_kconsumer_recv_cmd(struct lttng_consumer_local_data *ctx,
 463                 int sock, struct pollfd *consumer_sockpoll)
 464 {
 465         ssize_t ret;
 466         enum lttcomm_return_code ret_code = LTTCOMM_CONSUMERD_SUCCESS;
 467         struct lttcomm_consumer_msg msg;
 468
 469         health_code_update();
 470
 471         ret = lttcomm_recv_unix_sock(sock, &msg, sizeof(msg));
 472         if (ret != sizeof(msg)) {
 473                 if (ret > 0) {
 474                         lttng_consumer_send_error(ctx, LTTCOMM_CONSUMERD_ERROR_RECV_CMD);
 475                         ret = -1;
 476                 }
 477                 return ret;
 478         }
 479
 480         health_code_update();
 481
 482         /* Deprecated command */
 483         assert(msg.cmd_type != LTTNG_CONSUMER_STOP);
 484
 485         health_code_update();
 486
 487         /* relayd needs RCU read-side protection */
 488         rcu_read_lock();
 489
 490         switch (msg.cmd_type) {
 491         case LTTNG_CONSUMER_ADD_RELAYD_SOCKET:
 492         {
 493                 /* Session daemon status message are handled in the following call. */
 494                 consumer_add_relayd_socket(msg.u.relayd_sock.net_index,
 495                                 msg.u.relayd_sock.type, ctx, sock, consumer_sockpoll,
 496                                 &msg.u.relayd_sock.sock, msg.u.relayd_sock.session_id,
 497                                 msg.u.relayd_sock.relayd_session_id);
 498                 goto end_nosignal;
 499         }
 500         case LTTNG_CONSUMER_ADD_CHANNEL:
 501         {
 502                 struct lttng_consumer_channel *new_channel;
 503                 int ret_recv;
 504
 505                 health_code_update();
 506
 507                 /* First send a status message before receiving the fds. */
 508                 ret = consumer_send_status_msg(sock, ret_code);
 509                 if (ret < 0) {
 510                         /* Somehow, the session daemon is not responding anymore. */
 511                         goto error_fatal;
 512                 }
 513
 514                 health_code_update();
 515
 516                 DBG("consumer_add_channel %" PRIu64, msg.u.channel.channel_key);
 517                 new_channel = consumer_allocate_channel(msg.u.channel.channel_key,
 518                                 msg.u.channel.session_id, msg.u.channel.pathname,
 519                                 msg.u.channel.name, msg.u.channel.uid, msg.u.channel.gid,
 520                                 msg.u.channel.relayd_id, msg.u.channel.output,
 521                                 msg.u.channel.tracefile_size,
 522                                 msg.u.channel.tracefile_count, 0,
 523                                 msg.u.channel.monitor,
 524                                 msg.u.channel.live_timer_interval,
 525                                 msg.u.channel.is_live,
 526                                 NULL, NULL);
 527                 if (new_channel == NULL) {
 528                         lttng_consumer_send_error(ctx, LTTCOMM_CONSUMERD_OUTFD_ERROR);
 529                         goto end_nosignal;
 530                 }
 531                 new_channel->nb_init_stream_left = msg.u.channel.nb_init_streams;
 532                 switch (msg.u.channel.output) {
 533                 case LTTNG_EVENT_SPLICE:
 534                         new_channel->output = CONSUMER_CHANNEL_SPLICE;
 535                         break;
 536                 case LTTNG_EVENT_MMAP:
 537                         new_channel->output = CONSUMER_CHANNEL_MMAP;
 538                         break;
 539                 default:
 540                         ERR("Channel output unknown %d", msg.u.channel.output);
 541                         goto end_nosignal;
 542                 }
 543
 544                 /* Translate and save channel type. */
 545                 switch (msg.u.channel.type) {
 546                 case CONSUMER_CHANNEL_TYPE_DATA:
 547                 case CONSUMER_CHANNEL_TYPE_METADATA:
 548                         new_channel->type = msg.u.channel.type;
 549                         break;
 550                 default:
 551                         assert(0);
 552                         goto end_nosignal;
 553                 };
 554
 555                 health_code_update();
 556
 557                 if (ctx->on_recv_channel != NULL) {
 558                         ret_recv = ctx->on_recv_channel(new_channel);
 559                         if (ret_recv == 0) {
 560                                 ret = consumer_add_channel(new_channel, ctx);
 561                         } else if (ret_recv < 0) {
 562                                 goto end_nosignal;
 563                         }
 564                 } else {
 565                         ret = consumer_add_channel(new_channel, ctx);
 566                 }
 567                 if (CONSUMER_CHANNEL_TYPE_DATA) {
 568                         consumer_timer_live_start(new_channel,
 569                                         msg.u.channel.live_timer_interval);
 570                 }
 571
 572                 health_code_update();
 573
 574                 /* If we received an error in add_channel, we need to report it. */
 575                 if (ret < 0) {
 576                         ret = consumer_send_status_msg(sock, ret);
 577                         if (ret < 0) {
 578                                 goto error_fatal;
 579                         }
 580                         goto end_nosignal;
 581                 }
 582
 583                 goto end_nosignal;
 584         }
 585         case LTTNG_CONSUMER_ADD_STREAM:
 586         {
 587                 int fd;
 588                 struct lttng_pipe *stream_pipe;
 589                 struct lttng_consumer_stream *new_stream;
 590                 struct lttng_consumer_channel *channel;
 591                 int alloc_ret = 0;
 592
 593                 /*
 594                  * Get stream's channel reference. Needed when adding the stream to the
 595                  * global hash table.
 596                  */
 597                 channel = consumer_find_channel(msg.u.stream.channel_key);
 598                 if (!channel) {
 599                         /*
 600                          * We could not find the channel. Can happen if cpu hotplug
 601                          * happens while tearing down.
 602                          */
 603                         ERR("Unable to find channel key %" PRIu64, msg.u.stream.channel_key);
 604                         ret_code = LTTCOMM_CONSUMERD_CHAN_NOT_FOUND;
 605                 }
 606
 607                 health_code_update();
 608
 609                 /* First send a status message before receiving the fds. */
 610                 ret = consumer_send_status_msg(sock, ret_code);
 611                 if (ret < 0) {
 612                         /* Somehow, the session daemon is not responding anymore. */
 613                         goto error_fatal;
 614                 }
 615
 616                 health_code_update();
 617
 618                 if (ret_code != LTTCOMM_CONSUMERD_SUCCESS) {
 619                         /* Channel was not found. */
 620                         goto end_nosignal;
 621                 }
 622
 623                 /* Blocking call */
 624                 health_poll_entry();
 625                 ret = lttng_consumer_poll_socket(consumer_sockpoll);
 626                 health_poll_exit();
 627                 if (ret) {
 628                         goto error_fatal;
 629                 }
 630
 631                 health_code_update();
 632
 633                 /* Get stream file descriptor from socket */
 634                 ret = lttcomm_recv_fds_unix_sock(sock, &fd, 1);
 635                 if (ret != sizeof(fd)) {
 636                         lttng_consumer_send_error(ctx, LTTCOMM_CONSUMERD_ERROR_RECV_FD);
 637                         rcu_read_unlock();
 638                         return ret;
 639                 }
 640
 641                 health_code_update();
 642
 643                 /*
 644                  * Send status code to session daemon only if the recv works. If the
 645                  * above recv() failed, the session daemon is notified through the
 646                  * error socket and the teardown is eventually done.
 647                  */
 648                 ret = consumer_send_status_msg(sock, ret_code);
 649                 if (ret < 0) {
 650                         /* Somehow, the session daemon is not responding anymore. */
 651                         goto end_nosignal;
 652                 }
 653
 654                 health_code_update();
 655
 656                 pthread_mutex_lock(&channel->lock);
 657                 new_stream = consumer_stream_create(
 658                                 channel,
 659                                 channel->key,
 660                                 fd,
 661                                 LTTNG_CONSUMER_ACTIVE_STREAM,
 662                                 channel->name,
 663                                 channel->uid,
 664                                 channel->gid,
 665                                 channel->relayd_id,
 666                                 channel->session_id,
 667                                 msg.u.stream.cpu,
 668                                 &alloc_ret,
 669                                 channel->type,
 670                                 channel->monitor);
 671                 if (new_stream == NULL) {
 672                         switch (alloc_ret) {
 673                         case -ENOMEM:
 674                         case -EINVAL:
 675                         default:
 676                                 lttng_consumer_send_error(ctx, LTTCOMM_CONSUMERD_OUTFD_ERROR);
 677                                 break;
 678                         }
 679                         pthread_mutex_unlock(&channel->lock);
 680                         goto end_nosignal;
 681                 }
 682
 683                 new_stream->wait_fd = fd;
 684                 ret = kernctl_get_max_subbuf_size(new_stream->wait_fd,
 685                                 &new_stream->max_sb_size);
 686                 if (ret < 0) {
 687                         pthread_mutex_unlock(&channel->lock);
 688                         ERR("Failed to get kernel maximal subbuffer size");
 689                         goto end_nosignal;
 690                 }
 691
 692                 /*
 693                  * We've just assigned the channel to the stream so increment the
 694                  * refcount right now. We don't need to increment the refcount for
 695                  * streams in no monitor because we handle manually the cleanup of
 696                  * those. It is very important to make sure there is NO prior
 697                  * consumer_del_stream() calls or else the refcount will be unbalanced.
 698                  */
 699                 if (channel->monitor) {
 700                         uatomic_inc(&new_stream->chan->refcount);
 701                 }
 702
 703                 /*
 704                  * The buffer flush is done on the session daemon side for the kernel
 705                  * so no need for the stream "hangup_flush_done" variable to be
 706                  * tracked. This is important for a kernel stream since we don't rely
 707                  * on the flush state of the stream to read data. It's not the case for
 708                  * user space tracing.
 709                  */
 710                 new_stream->hangup_flush_done = 0;
 711
 712                 health_code_update();
 713
 714                 if (ctx->on_recv_stream) {
 715                         ret = ctx->on_recv_stream(new_stream);
 716                         if (ret < 0) {
 717                                 consumer_stream_free(new_stream);
 718                                 goto end_nosignal;
 719                         }
 720                 }
 721
 722                 health_code_update();
 723
 724                 if (new_stream->metadata_flag) {
 725                         channel->metadata_stream = new_stream;
 726                 }
 727
 728                 /* Do not monitor this stream. */
 729                 if (!channel->monitor) {
 730                         DBG("Kernel consumer add stream %s in no monitor mode with "
 731                                         "relayd id %" PRIu64, new_stream->name,
 732                                         new_stream->relayd_id);
 733                         cds_list_add(&new_stream->send_node, &channel->streams.head);
 734                         pthread_mutex_unlock(&channel->lock);
 735                         break;
 736                 }
 737
 738                 /* Send stream to relayd if the stream has an ID. */
 739                 if (new_stream->relayd_id != (uint64_t) -1ULL) {
 740                         ret = consumer_send_relayd_stream(new_stream,
 741                                         new_stream->chan->pathname);
 742                         if (ret < 0) {
 743                                 pthread_mutex_unlock(&channel->lock);
 744                                 consumer_stream_free(new_stream);
 745                                 goto end_nosignal;
 746                         }
 747
 748                         /*
 749                          * If adding an extra stream to an already
 750                          * existing channel (e.g. cpu hotplug), we need
 751                          * to send the "streams_sent" command to relayd.
 752                          */
 753                         if (channel->streams_sent_to_relayd) {
 754                                 ret = consumer_send_relayd_streams_sent(
 755                                                 new_stream->relayd_id);
 756                                 if (ret < 0) {
 757                                         pthread_mutex_unlock(&channel->lock);
 758                                         goto end_nosignal;
 759                                 }
 760                         }
 761                 }
 762                 pthread_mutex_unlock(&channel->lock);
 763
 764                 /* Get the right pipe where the stream will be sent. */
 765                 if (new_stream->metadata_flag) {
 766                         ret = consumer_add_metadata_stream(new_stream);
 767                         if (ret) {
 768                                 ERR("Consumer add metadata stream %" PRIu64 " failed. Continuing",
 769                                                 new_stream->key);
 770                                 consumer_stream_free(new_stream);
 771                                 goto end_nosignal;
 772                         }
 773                         stream_pipe = ctx->consumer_metadata_pipe;
 774                 } else {
 775                         ret = consumer_add_data_stream(new_stream);
 776                         if (ret) {
 777                                 ERR("Consumer add stream %" PRIu64 " failed. Continuing",
 778                                                 new_stream->key);
 779                                 consumer_stream_free(new_stream);
 780                                 goto end_nosignal;
 781                         }
 782                         stream_pipe = ctx->consumer_data_pipe;
 783                 }
 784
 785                 /* Vitible to other threads */
 786                 new_stream->globally_visible = 1;
 787
 788                 health_code_update();
 789
 790                 ret = lttng_pipe_write(stream_pipe, &new_stream, sizeof(new_stream));
 791                 if (ret < 0) {
 792                         ERR("Consumer write %s stream to pipe %d",
 793                                         new_stream->metadata_flag ? "metadata" : "data",
 794                                         lttng_pipe_get_writefd(stream_pipe));
 795                         if (new_stream->metadata_flag) {
 796                                 consumer_del_stream_for_metadata(new_stream);
 797                         } else {
 798                                 consumer_del_stream_for_data(new_stream);
 799                         }
 800                         goto end_nosignal;
 801                 }
 802
 803                 DBG("Kernel consumer ADD_STREAM %s (fd: %d) with relayd id %" PRIu64,
 804                                 new_stream->name, fd, new_stream->relayd_stream_id);
 805                 break;
 806         }
 807         case LTTNG_CONSUMER_STREAMS_SENT:
 808         {
 809                 struct lttng_consumer_channel *channel;
 810
 811                 /*
 812                  * Get stream's channel reference. Needed when adding the stream to the
 813                  * global hash table.
 814                  */
 815                 channel = consumer_find_channel(msg.u.sent_streams.channel_key);
 816                 if (!channel) {
 817                         /*
 818                          * We could not find the channel. Can happen if cpu hotplug
 819                          * happens while tearing down.
 820                          */
 821                         ERR("Unable to find channel key %" PRIu64,
 822                                         msg.u.sent_streams.channel_key);
 823                         ret_code = LTTCOMM_CONSUMERD_CHAN_NOT_FOUND;
 824                 }
 825
 826                 health_code_update();
 827
 828                 /*
 829                  * Send status code to session daemon.
 830                  */
 831                 ret = consumer_send_status_msg(sock, ret_code);
 832                 if (ret < 0 || ret_code != LTTCOMM_CONSUMERD_SUCCESS) {
 833                         /* Somehow, the session daemon is not responding anymore. */
 834                         goto end_nosignal;
 835                 }
 836
 837                 health_code_update();
 838
 839                 /*
 840                  * We should not send this message if we don't monitor the
 841                  * streams in this channel.
 842                  */
 843                 if (!channel->monitor) {
 844                         break;
 845                 }
 846
 847                 health_code_update();
 848                 /* Send stream to relayd if the stream has an ID. */
 849                 if (msg.u.sent_streams.net_seq_idx != (uint64_t) -1ULL) {
 850                         ret = consumer_send_relayd_streams_sent(
 851                                         msg.u.sent_streams.net_seq_idx);
 852                         if (ret < 0) {
 853                                 goto end_nosignal;
 854                         }
 855                         channel->streams_sent_to_relayd = true;
 856                 }
 857                 break;
 858         }
 859         case LTTNG_CONSUMER_UPDATE_STREAM:
 860         {
 861                 rcu_read_unlock();
 862                 return -ENOSYS;
 863         }
 864         case LTTNG_CONSUMER_DESTROY_RELAYD:
 865         {
 866                 uint64_t index = msg.u.destroy_relayd.net_seq_idx;
 867                 struct consumer_relayd_sock_pair *relayd;
 868
 869                 DBG("Kernel consumer destroying relayd %" PRIu64, index);
 870
 871                 /* Get relayd reference if exists. */
 872                 relayd = consumer_find_relayd(index);
 873                 if (relayd == NULL) {
 874                         DBG("Unable to find relayd %" PRIu64, index);
 875                         ret_code = LTTCOMM_CONSUMERD_RELAYD_FAIL;
 876                 }
 877
 878                 /*
 879                  * Each relayd socket pair has a refcount of stream attached to it
 880                  * which tells if the relayd is still active or not depending on the
 881                  * refcount value.
 882                  *
 883                  * This will set the destroy flag of the relayd object and destroy it
 884                  * if the refcount reaches zero when called.
 885                  *
 886                  * The destroy can happen either here or when a stream fd hangs up.
 887                  */
 888                 if (relayd) {
 889                         consumer_flag_relayd_for_destroy(relayd);
 890                 }
 891
 892                 health_code_update();
 893
 894                 ret = consumer_send_status_msg(sock, ret_code);
 895                 if (ret < 0) {
 896                         /* Somehow, the session daemon is not responding anymore. */
 897                         goto error_fatal;
 898                 }
 899
 900                 goto end_nosignal;
 901         }
 902         case LTTNG_CONSUMER_DATA_PENDING:
 903         {
 904                 int32_t ret;
 905                 uint64_t id = msg.u.data_pending.session_id;
 906
 907                 DBG("Kernel consumer data pending command for id %" PRIu64, id);
 908
 909                 ret = consumer_data_pending(id);
 910
 911                 health_code_update();
 912
 913                 /* Send back returned value to session daemon */
 914                 ret = lttcomm_send_unix_sock(sock, &ret, sizeof(ret));
 915                 if (ret < 0) {
 916                         PERROR("send data pending ret code");
 917                         goto error_fatal;
 918                 }
 919
 920                 /*
 921                  * No need to send back a status message since the data pending
 922                  * returned value is the response.
 923                  */
 924                 break;
 925         }
 926         case LTTNG_CONSUMER_SNAPSHOT_CHANNEL:
 927         {
 928                 if (msg.u.snapshot_channel.metadata == 1) {
 929                         ret = lttng_kconsumer_snapshot_metadata(msg.u.snapshot_channel.key,
 930                                         msg.u.snapshot_channel.pathname,
 931                                         msg.u.snapshot_channel.relayd_id, ctx);
 932                         if (ret < 0) {
 933                                 ERR("Snapshot metadata failed");
 934                                 ret_code = LTTCOMM_CONSUMERD_ERROR_METADATA;
 935                         }
 936                 } else {
 937                         ret = lttng_kconsumer_snapshot_channel(msg.u.snapshot_channel.key,
 938                                         msg.u.snapshot_channel.pathname,
 939                                         msg.u.snapshot_channel.relayd_id,
 940                                         msg.u.snapshot_channel.nb_packets_per_stream,
 941                                         ctx);
 942                         if (ret < 0) {
 943                                 ERR("Snapshot channel failed");
 944                                 ret_code = LTTCOMM_CONSUMERD_CHAN_NOT_FOUND;
 945                         }
 946                 }
 947
 948                 health_code_update();
 949
 950                 ret = consumer_send_status_msg(sock, ret_code);
 951                 if (ret < 0) {
 952                         /* Somehow, the session daemon is not responding anymore. */
 953                         goto end_nosignal;
 954                 }
 955                 break;
 956         }
 957         case LTTNG_CONSUMER_DESTROY_CHANNEL:
 958         {
 959                 uint64_t key = msg.u.destroy_channel.key;
 960                 struct lttng_consumer_channel *channel;
 961
 962                 channel = consumer_find_channel(key);
 963                 if (!channel) {
 964                         ERR("Kernel consumer destroy channel %" PRIu64 " not found", key);
 965                         ret_code = LTTCOMM_CONSUMERD_CHAN_NOT_FOUND;
 966                 }
 967
 968                 health_code_update();
 969
 970                 ret = consumer_send_status_msg(sock, ret_code);
 971                 if (ret < 0) {
 972                         /* Somehow, the session daemon is not responding anymore. */
 973                         goto end_nosignal;
 974                 }
 975
 976                 health_code_update();
 977
 978                 /* Stop right now if no channel was found. */
 979                 if (!channel) {
 980                         goto end_nosignal;
 981                 }
 982
 983                 /*
 984                  * This command should ONLY be issued for channel with streams set in
 985                  * no monitor mode.
 986                  */
 987                 assert(!channel->monitor);
 988
 989                 /*
 990                  * The refcount should ALWAYS be 0 in the case of a channel in no
 991                  * monitor mode.
 992                  */
 993                 assert(!uatomic_sub_return(&channel->refcount, 1));
 994
 995                 consumer_del_channel(channel);
 996
 997                 goto end_nosignal;
 998         }
 999         case LTTNG_CONSUMER_DISCARDED_EVENTS:
1000         {
1001                 uint64_t ret;
1002                 struct lttng_consumer_channel *channel;
1003                 uint64_t id = msg.u.discarded_events.session_id;
1004                 uint64_t key = msg.u.discarded_events.channel_key;
1005
1006                 DBG("Kernel consumer discarded events command for session id %"
1007                                 PRIu64 ", channel key %" PRIu64, id, key);
1008
1009                 channel = consumer_find_channel(key);
1010                 if (!channel) {
1011                         ERR("Kernel consumer discarded events channel %"
1012                                         PRIu64 " not found", key);
1013                         ret = 0;
1014                 } else {
1015                         ret = channel->discarded_events;
1016                 }
1017
1018                 health_code_update();
1019
1020                 /* Send back returned value to session daemon */
1021                 ret = lttcomm_send_unix_sock(sock, &ret, sizeof(ret));
1022                 if (ret < 0) {
1023                         PERROR("send discarded events");
1024                         goto error_fatal;
1025                 }
1026
1027                 break;
1028         }
1029         case LTTNG_CONSUMER_LOST_PACKETS:
1030         {
1031                 uint64_t ret;
1032                 struct lttng_consumer_channel *channel;
1033                 uint64_t id = msg.u.lost_packets.session_id;
1034                 uint64_t key = msg.u.lost_packets.channel_key;
1035
1036                 DBG("Kernel consumer lost packets command for session id %"
1037                                 PRIu64 ", channel key %" PRIu64, id, key);
1038
1039                 channel = consumer_find_channel(key);
1040                 if (!channel) {
1041                         ERR("Kernel consumer lost packets channel %"
1042                                         PRIu64 " not found", key);
1043                         ret = 0;
1044                 } else {
1045                         ret = channel->lost_packets;
1046                 }
1047
1048                 health_code_update();
1049
1050                 /* Send back returned value to session daemon */
1051                 ret = lttcomm_send_unix_sock(sock, &ret, sizeof(ret));
1052                 if (ret < 0) {
1053                         PERROR("send lost packets");
1054                         goto error_fatal;
1055                 }
1056
1057                 break;
1058         }
1059         default:
1060                 goto end_nosignal;
1061         }
1062
1063 end_nosignal:
1064         rcu_read_unlock();
1065
1066         /*
1067          * Return 1 to indicate success since the 0 value can be a socket
1068          * shutdown during the recv() or send() call.
1069          */
1070         health_code_update();
1071         return 1;
1072
1073 error_fatal:
1074         rcu_read_unlock();
1075         /* This will issue a consumer stop. */
1076         return -1;
1077 }
1078
1079 /*
1080  * Sync metadata meaning request them to the session daemon and snapshot to the
1081  * metadata thread can consumer them.
1082  *
1083  * Metadata stream lock MUST be acquired.
1084  *
1085  * Return 0 if new metadatda is available, EAGAIN if the metadata stream
1086  * is empty or a negative value on error.
1087  */
1088 int lttng_kconsumer_sync_metadata(struct lttng_consumer_stream *metadata)
1089 {
1090         int ret;
1091
1092         assert(metadata);
1093
1094         ret = kernctl_buffer_flush(metadata->wait_fd);
1095         if (ret < 0) {
1096                 ERR("Failed to flush kernel stream");
1097                 goto end;
1098         }
1099
1100         ret = kernctl_snapshot(metadata->wait_fd);
1101         if (ret < 0) {
1102                 if (ret != -EAGAIN) {
1103                         ERR("Sync metadata, taking kernel snapshot failed.");
1104                         goto end;
1105                 }
1106                 DBG("Sync metadata, no new kernel metadata");
1107                 /* No new metadata, exit. */
1108                 ret = ENODATA;
1109                 goto end;
1110         }
1111
1112 end:
1113         return ret;
1114 }
1115
1116 static
1117 int extract_common_subbuffer_info(struct lttng_consumer_stream *stream,
1118                 struct stream_subbuffer *subbuf)
1119 {
1120         int ret;
1121
1122         ret = kernctl_get_subbuf_size(
1123                         stream->wait_fd, &subbuf->info.data.subbuf_size);
1124         if (ret) {
1125                 goto end;
1126         }
1127
1128         ret = kernctl_get_padded_subbuf_size(
1129                         stream->wait_fd, &subbuf->info.data.padded_subbuf_size);
1130         if (ret) {
1131                 goto end;
1132         }
1133
1134 end:
1135         return ret;
1136 }
1137
1138 static
1139 int extract_metadata_subbuffer_info(struct lttng_consumer_stream *stream,
1140                 struct stream_subbuffer *subbuf)
1141 {
1142         int ret;
1143
1144         ret = extract_common_subbuffer_info(stream, subbuf);
1145         if (ret) {
1146                 goto end;
1147         }
1148
1149         ret = kernctl_get_metadata_version(
1150                         stream->wait_fd, &subbuf->info.metadata.version);
1151         if (ret) {
1152                 goto end;
1153         }
1154
1155 end:
1156         return ret;
1157 }
1158
1159 static
1160 int extract_data_subbuffer_info(struct lttng_consumer_stream *stream,
1161                 struct stream_subbuffer *subbuf)
1162 {
1163         int ret;
1164
1165         ret = extract_common_subbuffer_info(stream, subbuf);
1166         if (ret) {
1167                 goto end;
1168         }
1169
1170         ret = kernctl_get_packet_size(
1171                         stream->wait_fd, &subbuf->info.data.packet_size);
1172         if (ret < 0) {
1173                 PERROR("Failed to get sub-buffer packet size");
1174                 goto end;
1175         }
1176
1177         ret = kernctl_get_content_size(
1178                         stream->wait_fd, &subbuf->info.data.content_size);
1179         if (ret < 0) {
1180                 PERROR("Failed to get sub-buffer content size");
1181                 goto end;
1182         }
1183
1184         ret = kernctl_get_timestamp_begin(
1185                         stream->wait_fd, &subbuf->info.data.timestamp_begin);
1186         if (ret < 0) {
1187                 PERROR("Failed to get sub-buffer begin timestamp");
1188                 goto end;
1189         }
1190
1191         ret = kernctl_get_timestamp_end(
1192                         stream->wait_fd, &subbuf->info.data.timestamp_end);
1193         if (ret < 0) {
1194                 PERROR("Failed to get sub-buffer end timestamp");
1195                 goto end;
1196         }
1197
1198         ret = kernctl_get_events_discarded(
1199                         stream->wait_fd, &subbuf->info.data.events_discarded);
1200         if (ret) {
1201                 PERROR("Failed to get sub-buffer events discarded count");
1202                 goto end;
1203         }
1204
1205         ret = kernctl_get_sequence_number(stream->wait_fd,
1206                         &subbuf->info.data.sequence_number.value);
1207         if (ret) {
1208                 /* May not be supported by older LTTng-modules. */
1209                 if (ret != -ENOTTY) {
1210                         PERROR("Failed to get sub-buffer sequence number");
1211                         goto end;
1212                 }
1213         } else {
1214                 subbuf->info.data.sequence_number.is_set = true;
1215         }
1216
1217         ret = kernctl_get_stream_id(
1218                         stream->wait_fd, &subbuf->info.data.stream_id);
1219         if (ret < 0) {
1220                 PERROR("Failed to get stream id");
1221                 goto end;
1222         }
1223
1224         ret = kernctl_get_instance_id(stream->wait_fd,
1225                         &subbuf->info.data.stream_instance_id.value);
1226         if (ret) {
1227                 /* May not be supported by older LTTng-modules. */
1228                 if (ret != -ENOTTY) {
1229                         PERROR("Failed to get stream instance id");
1230                         goto end;
1231                 }
1232         } else {
1233                 subbuf->info.data.stream_instance_id.is_set = true;
1234         }
1235 end:
1236         return ret;
1237 }
1238
1239 static
1240 int get_subbuffer_common(struct lttng_consumer_stream *stream,
1241                 struct stream_subbuffer *subbuffer)
1242 {
1243         int ret;
1244
1245         ret = kernctl_get_next_subbuf(stream->wait_fd);
1246         if (ret) {
1247                 goto end;
1248         }
1249
1250         ret = stream->read_subbuffer_ops.extract_subbuffer_info(
1251                         stream, subbuffer);
1252 end:
1253         return ret;
1254 }
1255
1256 static
1257 int get_next_subbuffer_splice(struct lttng_consumer_stream *stream,
1258                 struct stream_subbuffer *subbuffer)
1259 {
1260         int ret;
1261
1262         ret = get_subbuffer_common(stream, subbuffer);
1263         if (ret) {
1264                 goto end;
1265         }
1266
1267         subbuffer->buffer.fd = stream->wait_fd;
1268 end:
1269         return ret;
1270 }
1271
1272 static
1273 int get_next_subbuffer_mmap(struct lttng_consumer_stream *stream,
1274                 struct stream_subbuffer *subbuffer)
1275 {
1276         int ret;
1277         const char *addr;
1278
1279         ret = get_subbuffer_common(stream, subbuffer);
1280         if (ret) {
1281                 goto end;
1282         }
1283
1284         ret = get_current_subbuf_addr(stream, &addr);
1285         if (ret) {
1286                 goto end;
1287         }
1288
1289         subbuffer->buffer.buffer = lttng_buffer_view_init(
1290                         addr, 0, subbuffer->info.data.padded_subbuf_size);
1291 end:
1292         return ret;
1293 }
1294
1295 static
1296 int put_next_subbuffer(struct lttng_consumer_stream *stream,
1297                 struct stream_subbuffer *subbuffer)
1298 {
1299         const int ret = kernctl_put_next_subbuf(stream->wait_fd);
1300
1301         if (ret) {
1302                 if (ret == -EFAULT) {
1303                         PERROR("Error in unreserving sub buffer");
1304                 } else if (ret == -EIO) {
1305                         /* Should never happen with newer LTTng versions */
1306                         PERROR("Reader has been pushed by the writer, last sub-buffer corrupted");
1307                 }
1308         }
1309
1310         return ret;
1311 }
1312
1313 static void lttng_kconsumer_set_stream_ops(
1314                 struct lttng_consumer_stream *stream)
1315 {
1316         if (stream->chan->output == CONSUMER_CHANNEL_MMAP) {
1317                 stream->read_subbuffer_ops.get_next_subbuffer =
1318                                 get_next_subbuffer_mmap;
1319         } else {
1320                 stream->read_subbuffer_ops.get_next_subbuffer =
1321                                 get_next_subbuffer_splice;
1322         }
1323
1324         if (stream->metadata_flag) {
1325                 stream->read_subbuffer_ops.extract_subbuffer_info =
1326                                 extract_metadata_subbuffer_info;
1327         } else {
1328                 stream->read_subbuffer_ops.extract_subbuffer_info =
1329                                 extract_data_subbuffer_info;
1330                 if (stream->chan->is_live) {
1331                         stream->read_subbuffer_ops.send_live_beacon =
1332                                         consumer_flush_kernel_index;
1333                 }
1334         }
1335
1336         stream->read_subbuffer_ops.put_next_subbuffer = put_next_subbuffer;
1337 }
1338
1339 int lttng_kconsumer_on_recv_stream(struct lttng_consumer_stream *stream)
1340 {
1341         int ret;
1342
1343         assert(stream);
1344
1345         /*
1346          * Don't create anything if this is set for streaming or should not be
1347          * monitored.
1348          */
1349         if (stream->relayd_id == (uint64_t) -1ULL && stream->chan->monitor) {
1350                 ret = utils_create_stream_file(stream->chan->pathname, stream->name,
1351                                 stream->chan->tracefile_size, stream->tracefile_count_current,
1352                                 stream->uid, stream->gid, NULL);
1353                 if (ret < 0) {
1354                         goto error;
1355                 }
1356                 stream->out_fd = ret;
1357                 stream->tracefile_size_current = 0;
1358
1359                 if (!stream->metadata_flag) {
1360                         struct lttng_index_file *index_file;
1361
1362                         index_file = lttng_index_file_create(stream->chan->pathname,
1363                                         stream->name, stream->uid, stream->gid,
1364                                         stream->chan->tracefile_size,
1365                                         stream->tracefile_count_current,
1366                                         CTF_INDEX_MAJOR, CTF_INDEX_MINOR);
1367                         if (!index_file) {
1368                                 goto error;
1369                         }
1370                         stream->index_file = index_file;
1371                 }
1372         }
1373
1374         if (stream->output == LTTNG_EVENT_MMAP) {
1375                 /* get the len of the mmap region */
1376                 unsigned long mmap_len;
1377
1378                 ret = kernctl_get_mmap_len(stream->wait_fd, &mmap_len);
1379                 if (ret != 0) {
1380                         PERROR("kernctl_get_mmap_len");
1381                         goto error_close_fd;
1382                 }
1383                 stream->mmap_len = (size_t) mmap_len;
1384
1385                 stream->mmap_base = mmap(NULL, stream->mmap_len, PROT_READ,
1386                                 MAP_PRIVATE, stream->wait_fd, 0);
1387                 if (stream->mmap_base == MAP_FAILED) {
1388                         PERROR("Error mmaping");
1389                         ret = -1;
1390                         goto error_close_fd;
1391                 }
1392         }
1393
1394         lttng_kconsumer_set_stream_ops(stream);
1395
1396         /* we return 0 to let the library handle the FD internally */
1397         return 0;
1398
1399 error_close_fd:
1400         if (stream->out_fd >= 0) {
1401                 int err;
1402
1403                 err = close(stream->out_fd);
1404                 assert(!err);
1405                 stream->out_fd = -1;
1406         }
1407 error:
1408         return ret;
1409 }
1410
1411 /*
1412  * Check if data is still being extracted from the buffers for a specific
1413  * stream. Consumer data lock MUST be acquired before calling this function
1414  * and the stream lock.
1415  *
1416  * Return 1 if the traced data are still getting read else 0 meaning that the
1417  * data is available for trace viewer reading.
1418  */
1419 int lttng_kconsumer_data_pending(struct lttng_consumer_stream *stream)
1420 {
1421         int ret;
1422
1423         assert(stream);
1424
1425         if (stream->endpoint_status != CONSUMER_ENDPOINT_ACTIVE) {
1426                 ret = 0;
1427                 goto end;
1428         }
1429
1430         ret = kernctl_get_next_subbuf(stream->wait_fd);
1431         if (ret == 0) {
1432                 /* There is still data so let's put back this subbuffer. */
1433                 ret = kernctl_put_subbuf(stream->wait_fd);
1434                 assert(ret == 0);
1435                 ret = 1;   /* Data is pending */
1436                 goto end;
1437         }
1438
1439         /* Data is NOT pending and ready to be read. */
1440         ret = 0;
1441
1442 end:
1443         return ret;
1444 }