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
  46 #include "kernel-consumer.h"
  47
  48 extern struct lttng_consumer_global_data consumer_data;
  49 extern int consumer_poll_timeout;
  50 extern volatile int consumer_quit;
  51
  52 /*
  53  * Take a snapshot for a specific fd
  54  *
  55  * Returns 0 on success, < 0 on error
  56  */
  57 int lttng_kconsumer_take_snapshot(struct lttng_consumer_stream *stream)
  58 {
  59         int ret = 0;
  60         int infd = stream->wait_fd;
  61
  62         ret = kernctl_snapshot(infd);
  63         if (ret != 0) {
  64                 PERROR("Getting sub-buffer snapshot.");
  65                 ret = -errno;
  66         }
  67
  68         return ret;
  69 }
  70
  71 /*
  72  * Get the produced position
  73  *
  74  * Returns 0 on success, < 0 on error
  75  */
  76 int lttng_kconsumer_get_produced_snapshot(struct lttng_consumer_stream *stream,
  77                 unsigned long *pos)
  78 {
  79         int ret;
  80         int infd = stream->wait_fd;
  81
  82         ret = kernctl_snapshot_get_produced(infd, pos);
  83         if (ret != 0) {
  84                 PERROR("kernctl_snapshot_get_produced");
  85                 ret = -errno;
  86         }
  87
  88         return ret;
  89 }
  90
  91 /*
  92  * Get the consumerd position
  93  *
  94  * Returns 0 on success, < 0 on error
  95  */
  96 int lttng_kconsumer_get_consumed_snapshot(struct lttng_consumer_stream *stream,
  97                 unsigned long *pos)
  98 {
  99         int ret;
 100         int infd = stream->wait_fd;
 101
 102         ret = kernctl_snapshot_get_consumed(infd, pos);
 103         if (ret != 0) {
 104                 PERROR("kernctl_snapshot_get_consumed");
 105                 ret = -errno;
 106         }
 107
 108         return ret;
 109 }
 110
 111 /*
 112  * Take a snapshot of all the stream of a channel
 113  *
 114  * Returns 0 on success, < 0 on error
 115  */
 116 int lttng_kconsumer_snapshot_channel(uint64_t key, char *path,
 117                 uint64_t relayd_id, uint64_t nb_packets_per_stream,
 118                 struct lttng_consumer_local_data *ctx)
 119 {
 120         int ret;
 121         struct lttng_consumer_channel *channel;
 122         struct lttng_consumer_stream *stream;
 123
 124         DBG("Kernel consumer snapshot channel %" PRIu64, key);
 125
 126         rcu_read_lock();
 127
 128         channel = consumer_find_channel(key);
 129         if (!channel) {
 130                 ERR("No channel found for key %" PRIu64, key);
 131                 ret = -1;
 132                 goto end;
 133         }
 134
 135         /* Splice is not supported yet for channel snapshot. */
 136         if (channel->output != CONSUMER_CHANNEL_MMAP) {
 137                 ERR("Unsupported output %d", channel->output);
 138                 ret = -1;
 139                 goto end;
 140         }
 141
 142         cds_list_for_each_entry(stream, &channel->streams.head, send_node) {
 143                 /* Are we at a position _before_ the first available packet ? */
 144                 bool before_first_packet = true;
 145                 unsigned long consumed_pos, produced_pos;
 146
 147                 health_code_update();
 148
 149                 /*
 150                  * Lock stream because we are about to change its state.
 151                  */
 152                 pthread_mutex_lock(&stream->lock);
 153
 154                 /*
 155                  * Assign the received relayd ID so we can use it for streaming. The streams
 156                  * are not visible to anyone so this is OK to change it.
 157                  */
 158                 stream->net_seq_idx = relayd_id;
 159                 channel->relayd_id = relayd_id;
 160                 if (relayd_id != (uint64_t) -1ULL) {
 161                         ret = consumer_send_relayd_stream(stream, path);
 162                         if (ret < 0) {
 163                                 ERR("sending stream to relayd");
 164                                 goto end_unlock;
 165                         }
 166                 } else {
 167                         ret = utils_create_stream_file(path, stream->name,
 168                                         stream->chan->tracefile_size,
 169                                         stream->tracefile_count_current,
 170                                         stream->uid, stream->gid, NULL);
 171                         if (ret < 0) {
 172                                 ERR("utils_create_stream_file");
 173                                 goto end_unlock;
 174                         }
 175
 176                         stream->out_fd = ret;
 177                         stream->tracefile_size_current = 0;
 178
 179                         DBG("Kernel consumer snapshot stream %s/%s (%" PRIu64 ")",
 180                                         path, stream->name, stream->key);
 181                 }
 182                 if (relayd_id != -1ULL) {
 183                         ret = consumer_send_relayd_streams_sent(relayd_id);
 184                         if (ret < 0) {
 185                                 ERR("sending streams sent to relayd");
 186                                 goto end_unlock;
 187                         }
 188                         channel->streams_sent_to_relayd = true;
 189                 }
 190
 191                 ret = kernctl_buffer_flush_empty(stream->wait_fd);
 192                 if (ret < 0) {
 193                         /*
 194                          * Doing a buffer flush which does not take into
 195                          * account empty packets. This is not perfect
 196                          * for stream intersection, but required as a
 197                          * fall-back when "flush_empty" is not
 198                          * implemented by lttng-modules.
 199                          */
 200                         ret = kernctl_buffer_flush(stream->wait_fd);
 201                         if (ret < 0) {
 202                                 ERR("Failed to flush kernel stream");
 203                                 goto end_unlock;
 204                         }
 205                 }
 206
 207                 ret = lttng_kconsumer_take_snapshot(stream);
 208                 if (ret < 0) {
 209                         ERR("Taking kernel snapshot");
 210                         goto end_unlock;
 211                 }
 212
 213                 ret = lttng_kconsumer_get_produced_snapshot(stream, &produced_pos);
 214                 if (ret < 0) {
 215                         ERR("Produced kernel snapshot position");
 216                         goto end_unlock;
 217                 }
 218
 219                 ret = lttng_kconsumer_get_consumed_snapshot(stream, &consumed_pos);
 220                 if (ret < 0) {
 221                         ERR("Consumerd kernel snapshot position");
 222                         goto end_unlock;
 223                 }
 224
 225                 if (stream->max_sb_size == 0) {
 226                         ret = kernctl_get_max_subbuf_size(stream->wait_fd,
 227                                         &stream->max_sb_size);
 228                         if (ret < 0) {
 229                                 ERR("Getting kernel max_sb_size");
 230                                 ret = -errno;
 231                                 goto end_unlock;
 232                         }
 233                 }
 234
 235                 consumed_pos = consumer_get_consume_start_pos(consumed_pos,
 236                                 produced_pos, nb_packets_per_stream,
 237                                 stream->max_sb_size);
 238
 239                 while (consumed_pos < produced_pos) {
 240                         ssize_t read_len;
 241                         unsigned long len, padded_len;
 242                         int lost_packet = 0;
 243
 244                         health_code_update();
 245
 246                         DBG("Kernel consumer taking snapshot at pos %lu", consumed_pos);
 247
 248                         ret = kernctl_get_subbuf(stream->wait_fd, &consumed_pos);
 249                         if (ret < 0) {
 250                                 if (errno != EAGAIN) {
 251                                         PERROR("kernctl_get_subbuf snapshot");
 252                                         ret = -errno;
 253                                         goto end_unlock;
 254                                 }
 255                                 DBG("Kernel consumer get subbuf failed. Skipping it.");
 256                                 consumed_pos += stream->max_sb_size;
 257
 258                                 /*
 259                                  * Start accounting lost packets only when we
 260                                  * already have extracted packets (to match the
 261                                  * content of the final snapshot).
 262                                  */
 263                                 if (!before_first_packet) {
 264                                         lost_packet = 1;
 265                                 }
 266                                 continue;
 267                         }
 268
 269                         ret = kernctl_get_subbuf_size(stream->wait_fd, &len);
 270                         if (ret < 0) {
 271                                 ERR("Snapshot kernctl_get_subbuf_size");
 272                                 ret = -errno;
 273                                 goto error_put_subbuf;
 274                         }
 275
 276                         ret = kernctl_get_padded_subbuf_size(stream->wait_fd, &padded_len);
 277                         if (ret < 0) {
 278                                 ERR("Snapshot kernctl_get_padded_subbuf_size");
 279                                 ret = -errno;
 280                                 goto error_put_subbuf;
 281                         }
 282
 283                         read_len = lttng_consumer_on_read_subbuffer_mmap(ctx, stream, len,
 284                                         padded_len - len, NULL);
 285                         /*
 286                          * We write the padded len in local tracefiles but the data len
 287                          * when using a relay. Display the error but continue processing
 288                          * to try to release the subbuffer.
 289                          */
 290                         if (relayd_id != (uint64_t) -1ULL) {
 291                                 if (read_len != len) {
 292                                         ERR("Error sending to the relay (ret: %zd != len: %lu)",
 293                                                         read_len, len);
 294                                 }
 295                         } else {
 296                                 if (read_len != padded_len) {
 297                                         ERR("Error writing to tracefile (ret: %zd != len: %lu)",
 298                                                         read_len, padded_len);
 299                                 }
 300                         }
 301
 302                         ret = kernctl_put_subbuf(stream->wait_fd);
 303                         if (ret < 0) {
 304                                 ERR("Snapshot kernctl_put_subbuf");
 305                                 ret = -errno;
 306                                 goto end_unlock;
 307                         }
 308                         consumed_pos += stream->max_sb_size;
 309
 310                         /*
 311                          * Only account lost packets located between
 312                          * succesfully extracted packets (do not account before
 313                          * and after since they are not visible in the
 314                          * resulting snapshot).
 315                          */
 316                         stream->chan->lost_packets += lost_packet;
 317                         lost_packet = 0;
 318                         before_first_packet = false;
 319                 }
 320
 321                 if (relayd_id == (uint64_t) -1ULL) {
 322                         if (stream->out_fd >= 0) {
 323                                 ret = close(stream->out_fd);
 324                                 if (ret < 0) {
 325                                         PERROR("Kernel consumer snapshot close out_fd");
 326                                         goto end_unlock;
 327                                 }
 328                                 stream->out_fd = -1;
 329                         }
 330                 } else {
 331                         close_relayd_stream(stream);
 332                         stream->net_seq_idx = (uint64_t) -1ULL;
 333                 }
 334                 pthread_mutex_unlock(&stream->lock);
 335         }
 336
 337         /* All good! */
 338         ret = 0;
 339         goto end;
 340
 341 error_put_subbuf:
 342         ret = kernctl_put_subbuf(stream->wait_fd);
 343         if (ret < 0) {
 344                 ret = -errno;
 345                 ERR("Snapshot kernctl_put_subbuf error path");
 346         }
 347 end_unlock:
 348         pthread_mutex_unlock(&stream->lock);
 349 end:
 350         rcu_read_unlock();
 351         return ret;
 352 }
 353
 354 /*
 355  * Read the whole metadata available for a snapshot.
 356  *
 357  * Returns 0 on success, < 0 on error
 358  */
 359 int lttng_kconsumer_snapshot_metadata(uint64_t key, char *path,
 360                 uint64_t relayd_id, struct lttng_consumer_local_data *ctx)
 361 {
 362         int ret, use_relayd = 0;
 363         ssize_t ret_read;
 364         struct lttng_consumer_channel *metadata_channel;
 365         struct lttng_consumer_stream *metadata_stream;
 366
 367         assert(ctx);
 368
 369         DBG("Kernel consumer snapshot metadata with key %" PRIu64 " at path %s",
 370                         key, path);
 371
 372         rcu_read_lock();
 373
 374         metadata_channel = consumer_find_channel(key);
 375         if (!metadata_channel) {
 376                 ERR("Kernel snapshot metadata not found for key %" PRIu64, key);
 377                 ret = -1;
 378                 goto error;
 379         }
 380
 381         metadata_stream = metadata_channel->metadata_stream;
 382         assert(metadata_stream);
 383
 384         /* Flag once that we have a valid relayd for the stream. */
 385         if (relayd_id != (uint64_t) -1ULL) {
 386                 use_relayd = 1;
 387         }
 388
 389         if (use_relayd) {
 390                 ret = consumer_send_relayd_stream(metadata_stream, path);
 391                 if (ret < 0) {
 392                         goto error;
 393                 }
 394         } else {
 395                 ret = utils_create_stream_file(path, metadata_stream->name,
 396                                 metadata_stream->chan->tracefile_size,
 397                                 metadata_stream->tracefile_count_current,
 398                                 metadata_stream->uid, metadata_stream->gid, NULL);
 399                 if (ret < 0) {
 400                         goto error;
 401                 }
 402                 metadata_stream->out_fd = ret;
 403         }
 404
 405         do {
 406                 health_code_update();
 407
 408                 ret_read = lttng_kconsumer_read_subbuffer(metadata_stream, ctx);
 409                 if (ret_read < 0) {
 410                         if (ret_read != -EAGAIN) {
 411                                 ERR("Kernel snapshot reading metadata subbuffer (ret: %zd)",
 412                                                 ret_read);
 413                                 goto error;
 414                         }
 415                         /* ret_read is negative at this point so we will exit the loop. */
 416                         continue;
 417                 }
 418         } while (ret_read >= 0);
 419
 420         if (use_relayd) {
 421                 close_relayd_stream(metadata_stream);
 422                 metadata_stream->net_seq_idx = (uint64_t) -1ULL;
 423         } else {
 424                 if (metadata_stream->out_fd >= 0) {
 425                         ret = close(metadata_stream->out_fd);
 426                         if (ret < 0) {
 427                                 PERROR("Kernel consumer snapshot metadata close out_fd");
 428                                 /*
 429                                  * Don't go on error here since the snapshot was successful at this
 430                                  * point but somehow the close failed.
 431                                  */
 432                         }
 433                         metadata_stream->out_fd = -1;
 434                 }
 435         }
 436
 437         ret = 0;
 438
 439         cds_list_del(&metadata_stream->send_node);
 440         consumer_stream_destroy(metadata_stream, NULL);
 441         metadata_channel->metadata_stream = NULL;
 442 error:
 443         rcu_read_unlock();
 444         return ret;
 445 }
 446
 447 /*
 448  * Receive command from session daemon and process it.
 449  *
 450  * Return 1 on success else a negative value or 0.
 451  */
 452 int lttng_kconsumer_recv_cmd(struct lttng_consumer_local_data *ctx,
 453                 int sock, struct pollfd *consumer_sockpoll)
 454 {
 455         ssize_t ret;
 456         enum lttcomm_return_code ret_code = LTTCOMM_CONSUMERD_SUCCESS;
 457         struct lttcomm_consumer_msg msg;
 458
 459         health_code_update();
 460
 461         ret = lttcomm_recv_unix_sock(sock, &msg, sizeof(msg));
 462         if (ret != sizeof(msg)) {
 463                 if (ret > 0) {
 464                         lttng_consumer_send_error(ctx, LTTCOMM_CONSUMERD_ERROR_RECV_CMD);
 465                         ret = -1;
 466                 }
 467                 return ret;
 468         }
 469
 470         health_code_update();
 471
 472         /* Deprecated command */
 473         assert(msg.cmd_type != LTTNG_CONSUMER_STOP);
 474
 475         health_code_update();
 476
 477         /* relayd needs RCU read-side protection */
 478         rcu_read_lock();
 479
 480         switch (msg.cmd_type) {
 481         case LTTNG_CONSUMER_ADD_RELAYD_SOCKET:
 482         {
 483                 /* Session daemon status message are handled in the following call. */
 484                 ret = consumer_add_relayd_socket(msg.u.relayd_sock.net_index,
 485                                 msg.u.relayd_sock.type, ctx, sock, consumer_sockpoll,
 486                                 &msg.u.relayd_sock.sock, msg.u.relayd_sock.session_id,
 487                                  msg.u.relayd_sock.relayd_session_id);
 488                 goto end_nosignal;
 489         }
 490         case LTTNG_CONSUMER_ADD_CHANNEL:
 491         {
 492                 struct lttng_consumer_channel *new_channel;
 493                 int ret_recv;
 494
 495                 health_code_update();
 496
 497                 /* First send a status message before receiving the fds. */
 498                 ret = consumer_send_status_msg(sock, ret_code);
 499                 if (ret < 0) {
 500                         /* Somehow, the session daemon is not responding anymore. */
 501                         goto error_fatal;
 502                 }
 503
 504                 health_code_update();
 505
 506                 DBG("consumer_add_channel %" PRIu64, msg.u.channel.channel_key);
 507                 new_channel = consumer_allocate_channel(msg.u.channel.channel_key,
 508                                 msg.u.channel.session_id, msg.u.channel.pathname,
 509                                 msg.u.channel.name, msg.u.channel.uid, msg.u.channel.gid,
 510                                 msg.u.channel.relayd_id, msg.u.channel.output,
 511                                 msg.u.channel.tracefile_size,
 512                                 msg.u.channel.tracefile_count, 0,
 513                                 msg.u.channel.monitor,
 514                                 msg.u.channel.live_timer_interval,
 515                                 NULL, NULL);
 516                 if (new_channel == NULL) {
 517                         lttng_consumer_send_error(ctx, LTTCOMM_CONSUMERD_OUTFD_ERROR);
 518                         goto end_nosignal;
 519                 }
 520                 new_channel->nb_init_stream_left = msg.u.channel.nb_init_streams;
 521                 switch (msg.u.channel.output) {
 522                 case LTTNG_EVENT_SPLICE:
 523                         new_channel->output = CONSUMER_CHANNEL_SPLICE;
 524                         break;
 525                 case LTTNG_EVENT_MMAP:
 526                         new_channel->output = CONSUMER_CHANNEL_MMAP;
 527                         break;
 528                 default:
 529                         ERR("Channel output unknown %d", msg.u.channel.output);
 530                         goto end_nosignal;
 531                 }
 532
 533                 /* Translate and save channel type. */
 534                 switch (msg.u.channel.type) {
 535                 case CONSUMER_CHANNEL_TYPE_DATA:
 536                 case CONSUMER_CHANNEL_TYPE_METADATA:
 537                         new_channel->type = msg.u.channel.type;
 538                         break;
 539                 default:
 540                         assert(0);
 541                         goto end_nosignal;
 542                 };
 543
 544                 health_code_update();
 545
 546                 if (ctx->on_recv_channel != NULL) {
 547                         ret_recv = ctx->on_recv_channel(new_channel);
 548                         if (ret_recv == 0) {
 549                                 ret = consumer_add_channel(new_channel, ctx);
 550                         } else if (ret_recv < 0) {
 551                                 goto end_nosignal;
 552                         }
 553                 } else {
 554                         ret = consumer_add_channel(new_channel, ctx);
 555                 }
 556                 if (CONSUMER_CHANNEL_TYPE_DATA) {
 557                         consumer_timer_live_start(new_channel,
 558                                         msg.u.channel.live_timer_interval);
 559                 }
 560
 561                 health_code_update();
 562
 563                 /* If we received an error in add_channel, we need to report it. */
 564                 if (ret < 0) {
 565                         ret = consumer_send_status_msg(sock, ret);
 566                         if (ret < 0) {
 567                                 goto error_fatal;
 568                         }
 569                         goto end_nosignal;
 570                 }
 571
 572                 goto end_nosignal;
 573         }
 574         case LTTNG_CONSUMER_ADD_STREAM:
 575         {
 576                 int fd;
 577                 struct lttng_pipe *stream_pipe;
 578                 struct lttng_consumer_stream *new_stream;
 579                 struct lttng_consumer_channel *channel;
 580                 int alloc_ret = 0;
 581
 582                 /*
 583                  * Get stream's channel reference. Needed when adding the stream to the
 584                  * global hash table.
 585                  */
 586                 channel = consumer_find_channel(msg.u.stream.channel_key);
 587                 if (!channel) {
 588                         /*
 589                          * We could not find the channel. Can happen if cpu hotplug
 590                          * happens while tearing down.
 591                          */
 592                         ERR("Unable to find channel key %" PRIu64, msg.u.stream.channel_key);
 593                         ret_code = LTTCOMM_CONSUMERD_CHAN_NOT_FOUND;
 594                 }
 595
 596                 health_code_update();
 597
 598                 /* First send a status message before receiving the fds. */
 599                 ret = consumer_send_status_msg(sock, ret_code);
 600                 if (ret < 0) {
 601                         /* Somehow, the session daemon is not responding anymore. */
 602                         goto error_fatal;
 603                 }
 604
 605                 health_code_update();
 606
 607                 if (ret_code != LTTCOMM_CONSUMERD_SUCCESS) {
 608                         /* Channel was not found. */
 609                         goto end_nosignal;
 610                 }
 611
 612                 /* Blocking call */
 613                 health_poll_entry();
 614                 ret = lttng_consumer_poll_socket(consumer_sockpoll);
 615                 health_poll_exit();
 616                 if (ret) {
 617                         goto error_fatal;
 618                 }
 619
 620                 health_code_update();
 621
 622                 /* Get stream file descriptor from socket */
 623                 ret = lttcomm_recv_fds_unix_sock(sock, &fd, 1);
 624                 if (ret != sizeof(fd)) {
 625                         lttng_consumer_send_error(ctx, LTTCOMM_CONSUMERD_ERROR_RECV_FD);
 626                         rcu_read_unlock();
 627                         return ret;
 628                 }
 629
 630                 health_code_update();
 631
 632                 /*
 633                  * Send status code to session daemon only if the recv works. If the
 634                  * above recv() failed, the session daemon is notified through the
 635                  * error socket and the teardown is eventually done.
 636                  */
 637                 ret = consumer_send_status_msg(sock, ret_code);
 638                 if (ret < 0) {
 639                         /* Somehow, the session daemon is not responding anymore. */
 640                         goto end_nosignal;
 641                 }
 642
 643                 health_code_update();
 644
 645                 new_stream = consumer_allocate_stream(channel->key,
 646                                 fd,
 647                                 LTTNG_CONSUMER_ACTIVE_STREAM,
 648                                 channel->name,
 649                                 channel->uid,
 650                                 channel->gid,
 651                                 channel->relayd_id,
 652                                 channel->session_id,
 653                                 msg.u.stream.cpu,
 654                                 &alloc_ret,
 655                                 channel->type,
 656                                 channel->monitor);
 657                 if (new_stream == NULL) {
 658                         switch (alloc_ret) {
 659                         case -ENOMEM:
 660                         case -EINVAL:
 661                         default:
 662                                 lttng_consumer_send_error(ctx, LTTCOMM_CONSUMERD_OUTFD_ERROR);
 663                                 break;
 664                         }
 665                         goto end_nosignal;
 666                 }
 667
 668                 new_stream->chan = channel;
 669                 new_stream->wait_fd = fd;
 670                 switch (channel->output) {
 671                 case CONSUMER_CHANNEL_SPLICE:
 672                         new_stream->output = LTTNG_EVENT_SPLICE;
 673                         ret = utils_create_pipe(new_stream->splice_pipe);
 674                         if (ret < 0) {
 675                                 goto end_nosignal;
 676                         }
 677                         break;
 678                 case CONSUMER_CHANNEL_MMAP:
 679                         new_stream->output = LTTNG_EVENT_MMAP;
 680                         break;
 681                 default:
 682                         ERR("Stream output unknown %d", channel->output);
 683                         goto end_nosignal;
 684                 }
 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                 if (ctx->on_recv_stream) {
 709                         ret = ctx->on_recv_stream(new_stream);
 710                         if (ret < 0) {
 711                                 consumer_stream_free(new_stream);
 712                                 goto end_nosignal;
 713                         }
 714                 }
 715
 716                 health_code_update();
 717
 718                 if (new_stream->metadata_flag) {
 719                         channel->metadata_stream = new_stream;
 720                 }
 721
 722                 /* Do not monitor this stream. */
 723                 if (!channel->monitor) {
 724                         DBG("Kernel consumer add stream %s in no monitor mode with "
 725                                         "relayd id %" PRIu64, new_stream->name,
 726                                         new_stream->net_seq_idx);
 727                         cds_list_add(&new_stream->send_node, &channel->streams.head);
 728                         break;
 729                 }
 730
 731                 /* Send stream to relayd if the stream has an ID. */
 732                 if (new_stream->net_seq_idx != (uint64_t) -1ULL) {
 733                         ret = consumer_send_relayd_stream(new_stream,
 734                                         new_stream->chan->pathname);
 735                         if (ret < 0) {
 736                                 consumer_stream_free(new_stream);
 737                                 goto end_nosignal;
 738                         }
 739
 740                         /*
 741                          * If adding an extra stream to an already
 742                          * existing channel (e.g. cpu hotplug), we need
 743                          * to send the "streams_sent" command to relayd.
 744                          */
 745                         if (channel->streams_sent_to_relayd) {
 746                                 ret = consumer_send_relayd_streams_sent(
 747                                                 new_stream->net_seq_idx);
 748                                 if (ret < 0) {
 749                                         goto end_nosignal;
 750                                 }
 751                         }
 752                 }
 753
 754                 /* Get the right pipe where the stream will be sent. */
 755                 if (new_stream->metadata_flag) {
 756                         ret = consumer_add_metadata_stream(new_stream);
 757                         if (ret) {
 758                                 ERR("Consumer add metadata stream %" PRIu64 " failed. Continuing",
 759                                                 new_stream->key);
 760                                 consumer_stream_free(new_stream);
 761                                 goto end_nosignal;
 762                         }
 763                         stream_pipe = ctx->consumer_metadata_pipe;
 764                 } else {
 765                         ret = consumer_add_data_stream(new_stream);
 766                         if (ret) {
 767                                 ERR("Consumer add stream %" PRIu64 " failed. Continuing",
 768                                                 new_stream->key);
 769                                 consumer_stream_free(new_stream);
 770                                 goto end_nosignal;
 771                         }
 772                         stream_pipe = ctx->consumer_data_pipe;
 773                 }
 774
 775                 /* Vitible to other threads */
 776                 new_stream->globally_visible = 1;
 777
 778                 health_code_update();
 779
 780                 ret = lttng_pipe_write(stream_pipe, &new_stream, sizeof(new_stream));
 781                 if (ret < 0) {
 782                         ERR("Consumer write %s stream to pipe %d",
 783                                         new_stream->metadata_flag ? "metadata" : "data",
 784                                         lttng_pipe_get_writefd(stream_pipe));
 785                         if (new_stream->metadata_flag) {
 786                                 consumer_del_stream_for_metadata(new_stream);
 787                         } else {
 788                                 consumer_del_stream_for_data(new_stream);
 789                         }
 790                         goto end_nosignal;
 791                 }
 792
 793                 DBG("Kernel consumer ADD_STREAM %s (fd: %d) with relayd id %" PRIu64,
 794                                 new_stream->name, fd, new_stream->relayd_stream_id);
 795                 break;
 796         }
 797         case LTTNG_CONSUMER_STREAMS_SENT:
 798         {
 799                 struct lttng_consumer_channel *channel;
 800
 801                 /*
 802                  * Get stream's channel reference. Needed when adding the stream to the
 803                  * global hash table.
 804                  */
 805                 channel = consumer_find_channel(msg.u.sent_streams.channel_key);
 806                 if (!channel) {
 807                         /*
 808                          * We could not find the channel. Can happen if cpu hotplug
 809                          * happens while tearing down.
 810                          */
 811                         ERR("Unable to find channel key %" PRIu64,
 812                                         msg.u.sent_streams.channel_key);
 813                         ret_code = LTTCOMM_CONSUMERD_CHAN_NOT_FOUND;
 814                 }
 815
 816                 health_code_update();
 817
 818                 /*
 819                  * Send status code to session daemon.
 820                  */
 821                 ret = consumer_send_status_msg(sock, ret_code);
 822                 if (ret < 0 || ret_code != LTTCOMM_CONSUMERD_SUCCESS) {
 823                         /* Somehow, the session daemon is not responding anymore. */
 824                         goto end_nosignal;
 825                 }
 826
 827                 health_code_update();
 828
 829                 /*
 830                  * We should not send this message if we don't monitor the
 831                  * streams in this channel.
 832                  */
 833                 if (!channel->monitor) {
 834                         break;
 835                 }
 836
 837                 health_code_update();
 838                 /* Send stream to relayd if the stream has an ID. */
 839                 if (msg.u.sent_streams.net_seq_idx != (uint64_t) -1ULL) {
 840                         ret = consumer_send_relayd_streams_sent(
 841                                         msg.u.sent_streams.net_seq_idx);
 842                         if (ret < 0) {
 843                                 goto end_nosignal;
 844                         }
 845                         channel->streams_sent_to_relayd = true;
 846                 }
 847                 break;
 848         }
 849         case LTTNG_CONSUMER_UPDATE_STREAM:
 850         {
 851                 rcu_read_unlock();
 852                 return -ENOSYS;
 853         }
 854         case LTTNG_CONSUMER_DESTROY_RELAYD:
 855         {
 856                 uint64_t index = msg.u.destroy_relayd.net_seq_idx;
 857                 struct consumer_relayd_sock_pair *relayd;
 858
 859                 DBG("Kernel consumer destroying relayd %" PRIu64, index);
 860
 861                 /* Get relayd reference if exists. */
 862                 relayd = consumer_find_relayd(index);
 863                 if (relayd == NULL) {
 864                         DBG("Unable to find relayd %" PRIu64, index);
 865                         ret_code = LTTCOMM_CONSUMERD_RELAYD_FAIL;
 866                 }
 867
 868                 /*
 869                  * Each relayd socket pair has a refcount of stream attached to it
 870                  * which tells if the relayd is still active or not depending on the
 871                  * refcount value.
 872                  *
 873                  * This will set the destroy flag of the relayd object and destroy it
 874                  * if the refcount reaches zero when called.
 875                  *
 876                  * The destroy can happen either here or when a stream fd hangs up.
 877                  */
 878                 if (relayd) {
 879                         consumer_flag_relayd_for_destroy(relayd);
 880                 }
 881
 882                 health_code_update();
 883
 884                 ret = consumer_send_status_msg(sock, ret_code);
 885                 if (ret < 0) {
 886                         /* Somehow, the session daemon is not responding anymore. */
 887                         goto error_fatal;
 888                 }
 889
 890                 goto end_nosignal;
 891         }
 892         case LTTNG_CONSUMER_DATA_PENDING:
 893         {
 894                 int32_t ret;
 895                 uint64_t id = msg.u.data_pending.session_id;
 896
 897                 DBG("Kernel consumer data pending command for id %" PRIu64, id);
 898
 899                 ret = consumer_data_pending(id);
 900
 901                 health_code_update();
 902
 903                 /* Send back returned value to session daemon */
 904                 ret = lttcomm_send_unix_sock(sock, &ret, sizeof(ret));
 905                 if (ret < 0) {
 906                         PERROR("send data pending ret code");
 907                         goto error_fatal;
 908                 }
 909
 910                 /*
 911                  * No need to send back a status message since the data pending
 912                  * returned value is the response.
 913                  */
 914                 break;
 915         }
 916         case LTTNG_CONSUMER_SNAPSHOT_CHANNEL:
 917         {
 918                 if (msg.u.snapshot_channel.metadata == 1) {
 919                         ret = lttng_kconsumer_snapshot_metadata(msg.u.snapshot_channel.key,
 920                                         msg.u.snapshot_channel.pathname,
 921                                         msg.u.snapshot_channel.relayd_id, ctx);
 922                         if (ret < 0) {
 923                                 ERR("Snapshot metadata failed");
 924                                 ret_code = LTTCOMM_CONSUMERD_ERROR_METADATA;
 925                         }
 926                 } else {
 927                         ret = lttng_kconsumer_snapshot_channel(msg.u.snapshot_channel.key,
 928                                         msg.u.snapshot_channel.pathname,
 929                                         msg.u.snapshot_channel.relayd_id,
 930                                         msg.u.snapshot_channel.nb_packets_per_stream,
 931                                         ctx);
 932                         if (ret < 0) {
 933                                 ERR("Snapshot channel failed");
 934                                 ret_code = LTTCOMM_CONSUMERD_CHAN_NOT_FOUND;
 935                         }
 936                 }
 937
 938                 health_code_update();
 939
 940                 ret = consumer_send_status_msg(sock, ret_code);
 941                 if (ret < 0) {
 942                         /* Somehow, the session daemon is not responding anymore. */
 943                         goto end_nosignal;
 944                 }
 945                 break;
 946         }
 947         case LTTNG_CONSUMER_DESTROY_CHANNEL:
 948         {
 949                 uint64_t key = msg.u.destroy_channel.key;
 950                 struct lttng_consumer_channel *channel;
 951
 952                 channel = consumer_find_channel(key);
 953                 if (!channel) {
 954                         ERR("Kernel consumer destroy channel %" PRIu64 " not found", key);
 955                         ret_code = LTTCOMM_CONSUMERD_CHAN_NOT_FOUND;
 956                 }
 957
 958                 health_code_update();
 959
 960                 ret = consumer_send_status_msg(sock, ret_code);
 961                 if (ret < 0) {
 962                         /* Somehow, the session daemon is not responding anymore. */
 963                         goto end_nosignal;
 964                 }
 965
 966                 health_code_update();
 967
 968                 /* Stop right now if no channel was found. */
 969                 if (!channel) {
 970                         goto end_nosignal;
 971                 }
 972
 973                 /*
 974                  * This command should ONLY be issued for channel with streams set in
 975                  * no monitor mode.
 976                  */
 977                 assert(!channel->monitor);
 978
 979                 /*
 980                  * The refcount should ALWAYS be 0 in the case of a channel in no
 981                  * monitor mode.
 982                  */
 983                 assert(!uatomic_sub_return(&channel->refcount, 1));
 984
 985                 consumer_del_channel(channel);
 986
 987                 goto end_nosignal;
 988         }
 989         case LTTNG_CONSUMER_DISCARDED_EVENTS:
 990         {
 991                 uint64_t ret;
 992                 struct lttng_consumer_channel *channel;
 993                 uint64_t id = msg.u.discarded_events.session_id;
 994                 uint64_t key = msg.u.discarded_events.channel_key;
 995
 996                 DBG("Kernel consumer discarded events command for session id %"
 997                                 PRIu64 ", channel key %" PRIu64, id, key);
 998
 999                 channel = consumer_find_channel(key);
1000                 if (!channel) {
1001                         ERR("Kernel consumer discarded events channel %"
1002                                         PRIu64 " not found", key);
1003                         ret = 0;
1004                 } else {
1005                         ret = channel->discarded_events;
1006                 }
1007
1008                 health_code_update();
1009
1010                 /* Send back returned value to session daemon */
1011                 ret = lttcomm_send_unix_sock(sock, &ret, sizeof(ret));
1012                 if (ret < 0) {
1013                         PERROR("send discarded events");
1014                         goto error_fatal;
1015                 }
1016
1017                 break;
1018         }
1019         case LTTNG_CONSUMER_LOST_PACKETS:
1020         {
1021                 uint64_t ret;
1022                 struct lttng_consumer_channel *channel;
1023                 uint64_t id = msg.u.lost_packets.session_id;
1024                 uint64_t key = msg.u.lost_packets.channel_key;
1025
1026                 DBG("Kernel consumer lost packets command for session id %"
1027                                 PRIu64 ", channel key %" PRIu64, id, key);
1028
1029                 channel = consumer_find_channel(key);
1030                 if (!channel) {
1031                         ERR("Kernel consumer lost packets channel %"
1032                                         PRIu64 " not found", key);
1033                         ret = 0;
1034                 } else {
1035                         ret = channel->lost_packets;
1036                 }
1037
1038                 health_code_update();
1039
1040                 /* Send back returned value to session daemon */
1041                 ret = lttcomm_send_unix_sock(sock, &ret, sizeof(ret));
1042                 if (ret < 0) {
1043                         PERROR("send lost packets");
1044                         goto error_fatal;
1045                 }
1046
1047                 break;
1048         }
1049         default:
1050                 goto end_nosignal;
1051         }
1052
1053 end_nosignal:
1054         rcu_read_unlock();
1055
1056         /*
1057          * Return 1 to indicate success since the 0 value can be a socket
1058          * shutdown during the recv() or send() call.
1059          */
1060         health_code_update();
1061         return 1;
1062
1063 error_fatal:
1064         rcu_read_unlock();
1065         /* This will issue a consumer stop. */
1066         return -1;
1067 }
1068
1069 /*
1070  * Populate index values of a kernel stream. Values are set in big endian order.
1071  *
1072  * Return 0 on success or else a negative value.
1073  */
1074 static int get_index_values(struct ctf_packet_index *index, int infd)
1075 {
1076         int ret;
1077
1078         ret = kernctl_get_timestamp_begin(infd, &index->timestamp_begin);
1079         if (ret < 0) {
1080                 PERROR("kernctl_get_timestamp_begin");
1081                 goto error;
1082         }
1083         index->timestamp_begin = htobe64(index->timestamp_begin);
1084
1085         ret = kernctl_get_timestamp_end(infd, &index->timestamp_end);
1086         if (ret < 0) {
1087                 PERROR("kernctl_get_timestamp_end");
1088                 goto error;
1089         }
1090         index->timestamp_end = htobe64(index->timestamp_end);
1091
1092         ret = kernctl_get_events_discarded(infd, &index->events_discarded);
1093         if (ret < 0) {
1094                 PERROR("kernctl_get_events_discarded");
1095                 goto error;
1096         }
1097         index->events_discarded = htobe64(index->events_discarded);
1098
1099         ret = kernctl_get_content_size(infd, &index->content_size);
1100         if (ret < 0) {
1101                 PERROR("kernctl_get_content_size");
1102                 goto error;
1103         }
1104         index->content_size = htobe64(index->content_size);
1105
1106         ret = kernctl_get_packet_size(infd, &index->packet_size);
1107         if (ret < 0) {
1108                 PERROR("kernctl_get_packet_size");
1109                 goto error;
1110         }
1111         index->packet_size = htobe64(index->packet_size);
1112
1113         ret = kernctl_get_stream_id(infd, &index->stream_id);
1114         if (ret < 0) {
1115                 PERROR("kernctl_get_stream_id");
1116                 goto error;
1117         }
1118         index->stream_id = htobe64(index->stream_id);
1119
1120         ret = kernctl_get_instance_id(infd, &index->stream_instance_id);
1121         if (ret < 0) {
1122                 if (ret == -ENOTTY) {
1123                         /* Command not implemented by lttng-modules. */
1124                         index->stream_instance_id = -1ULL;
1125                         ret = 0;
1126                 } else {
1127                         PERROR("kernctl_get_instance_id");
1128                         goto error;
1129                 }
1130         }
1131         index->stream_instance_id = htobe64(index->stream_instance_id);
1132
1133         ret = kernctl_get_sequence_number(infd, &index->packet_seq_num);
1134         if (ret < 0) {
1135                 if (ret == -ENOTTY) {
1136                         /* Command not implemented by lttng-modules. */
1137                         index->packet_seq_num = -1ULL;
1138                         ret = 0;
1139                 } else {
1140                         PERROR("kernctl_get_sequence_number");
1141                         goto error;
1142                 }
1143         }
1144         index->packet_seq_num = htobe64(index->packet_seq_num);
1145
1146 error:
1147         return ret;
1148 }
1149 /*
1150  * Sync metadata meaning request them to the session daemon and snapshot to the
1151  * metadata thread can consumer them.
1152  *
1153  * Metadata stream lock MUST be acquired.
1154  *
1155  * Return 0 if new metadatda is available, EAGAIN if the metadata stream
1156  * is empty or a negative value on error.
1157  */
1158 int lttng_kconsumer_sync_metadata(struct lttng_consumer_stream *metadata)
1159 {
1160         int ret;
1161
1162         assert(metadata);
1163
1164         ret = kernctl_buffer_flush(metadata->wait_fd);
1165         if (ret < 0) {
1166                 ERR("Failed to flush kernel stream");
1167                 goto end;
1168         }
1169
1170         ret = kernctl_snapshot(metadata->wait_fd);
1171         if (ret < 0) {
1172                 if (errno != EAGAIN) {
1173                         ERR("Sync metadata, taking kernel snapshot failed.");
1174                         goto end;
1175                 }
1176                 DBG("Sync metadata, no new kernel metadata");
1177                 /* No new metadata, exit. */
1178                 ret = ENODATA;
1179                 goto end;
1180         }
1181
1182 end:
1183         return ret;
1184 }
1185
1186 static
1187 int update_stream_stats(struct lttng_consumer_stream *stream)
1188 {
1189         int ret;
1190         uint64_t seq, discarded;
1191
1192         ret = kernctl_get_sequence_number(stream->wait_fd, &seq);
1193         if (ret < 0) {
1194                 if (ret == -ENOTTY) {
1195                         /* Command not implemented by lttng-modules. */
1196                         seq = -1ULL;
1197                         ret = 0;
1198                 } else {
1199                         PERROR("kernctl_get_sequence_number");
1200                         goto end;
1201                 }
1202         }
1203
1204         /*
1205          * Start the sequence when we extract the first packet in case we don't
1206          * start at 0 (for example if a consumer is not connected to the
1207          * session immediately after the beginning).
1208          */
1209         if (stream->last_sequence_number == -1ULL) {
1210                 stream->last_sequence_number = seq;
1211         } else if (seq > stream->last_sequence_number) {
1212                 stream->chan->lost_packets += seq -
1213                                 stream->last_sequence_number - 1;
1214         } else {
1215                 /* seq <= last_sequence_number */
1216                 ERR("Sequence number inconsistent : prev = %" PRIu64
1217                                 ", current = %" PRIu64,
1218                                 stream->last_sequence_number, seq);
1219                 ret = -1;
1220                 goto end;
1221         }
1222         stream->last_sequence_number = seq;
1223
1224         ret = kernctl_get_events_discarded(stream->wait_fd, &discarded);
1225         if (ret < 0) {
1226                 PERROR("kernctl_get_events_discarded");
1227                 goto end;
1228         }
1229         if (discarded < stream->last_discarded_events) {
1230                 /*
1231                  * Overflow has occurred. We assume only one wrap-around
1232                  * has occurred.
1233                  */
1234                 stream->chan->discarded_events += (1ULL << (CAA_BITS_PER_LONG - 1)) -
1235                         stream->last_discarded_events + discarded;
1236         } else {
1237                 stream->chan->discarded_events += discarded -
1238                         stream->last_discarded_events;
1239         }
1240         stream->last_discarded_events = discarded;
1241         ret = 0;
1242
1243 end:
1244         return ret;
1245 }
1246
1247 /*
1248  * Check if the local version of the metadata stream matches with the version
1249  * of the metadata stream in the kernel. If it was updated, set the reset flag
1250  * on the stream.
1251  */
1252 static
1253 int metadata_stream_check_version(int infd, struct lttng_consumer_stream *stream)
1254 {
1255         int ret;
1256         uint64_t cur_version;
1257
1258         ret = kernctl_get_metadata_version(infd, &cur_version);
1259         if (ret < 0) {
1260                 if (ret == -ENOTTY) {
1261                         /*
1262                          * LTTng-modules does not implement this
1263                          * command.
1264                          */
1265                         ret = 0;
1266                         goto end;
1267                 }
1268                 ERR("Failed to get the metadata version");
1269                 goto end;
1270         }
1271
1272         if (stream->metadata_version == cur_version) {
1273                 ret = 0;
1274                 goto end;
1275         }
1276
1277         DBG("New metadata version detected");
1278         stream->metadata_version = cur_version;
1279         stream->reset_metadata_flag = 1;
1280         ret = 0;
1281
1282 end:
1283         return ret;
1284 }
1285
1286 /*
1287  * Consume data on a file descriptor and write it on a trace file.
1288  */
1289 ssize_t lttng_kconsumer_read_subbuffer(struct lttng_consumer_stream *stream,
1290                 struct lttng_consumer_local_data *ctx)
1291 {
1292         unsigned long len, subbuf_size, padding;
1293         int err, write_index = 1;
1294         ssize_t ret = 0;
1295         int infd = stream->wait_fd;
1296         struct ctf_packet_index index;
1297
1298         DBG("In read_subbuffer (infd : %d)", infd);
1299
1300         /* Get the next subbuffer */
1301         err = kernctl_get_next_subbuf(infd);
1302         if (err != 0) {
1303                 /*
1304                  * This is a debug message even for single-threaded consumer,
1305                  * because poll() have more relaxed criterions than get subbuf,
1306                  * so get_subbuf may fail for short race windows where poll()
1307                  * would issue wakeups.
1308                  */
1309                 DBG("Reserving sub buffer failed (everything is normal, "
1310                                 "it is due to concurrency)");
1311                 ret = -errno;
1312                 goto end;
1313         }
1314
1315         /* Get the full subbuffer size including padding */
1316         err = kernctl_get_padded_subbuf_size(infd, &len);
1317         if (err != 0) {
1318                 PERROR("Getting sub-buffer len failed.");
1319                 err = kernctl_put_subbuf(infd);
1320                 if (err != 0) {
1321                         if (errno == EFAULT) {
1322                                 PERROR("Error in unreserving sub buffer\n");
1323                         } else if (errno == EIO) {
1324                                 /* Should never happen with newer LTTng versions */
1325                                 PERROR("Reader has been pushed by the writer, last sub-buffer corrupted.");
1326                         }
1327                         ret = -errno;
1328                         goto end;
1329                 }
1330                 ret = -errno;
1331                 goto end;
1332         }
1333
1334         if (!stream->metadata_flag) {
1335                 ret = get_index_values(&index, infd);
1336                 if (ret < 0) {
1337                         err = kernctl_put_subbuf(infd);
1338                         if (err != 0) {
1339                                 if (errno == EFAULT) {
1340                                         PERROR("Error in unreserving sub buffer\n");
1341                                 } else if (errno == EIO) {
1342                                         /* Should never happen with newer LTTng versions */
1343                                         PERROR("Reader has been pushed by the writer, last sub-buffer corrupted.");
1344                                 }
1345                                 ret = -errno;
1346                                 goto end;
1347                         }
1348                         goto end;
1349                 }
1350                 ret = update_stream_stats(stream);
1351                 if (ret < 0) {
1352                         err = kernctl_put_subbuf(infd);
1353                         if (err != 0) {
1354                                 if (err == -EFAULT) {
1355                                         PERROR("Error in unreserving sub buffer\n");
1356                                 } else if (err == -EIO) {
1357                                         /* Should never happen with newer LTTng versions */
1358                                         PERROR("Reader has been pushed by the writer, last sub-buffer corrupted.");
1359                                 }
1360                                 ret = err;
1361                                 goto end;
1362                         }
1363                         goto end;
1364                 }
1365         } else {
1366                 write_index = 0;
1367                 ret = metadata_stream_check_version(infd, stream);
1368                 if (ret < 0) {
1369                         err = kernctl_put_subbuf(infd);
1370                         if (err != 0) {
1371                                 if (err == -EFAULT) {
1372                                         PERROR("Error in unreserving sub buffer\n");
1373                                 } else if (err == -EIO) {
1374                                         /* Should never happen with newer LTTng versions */
1375                                         PERROR("Reader has been pushed by the writer, last sub-buffer corrupted.");
1376                                 }
1377                                 ret = err;
1378                                 goto end;
1379                         }
1380                         goto end;
1381                 }
1382         }
1383
1384         switch (stream->chan->output) {
1385         case CONSUMER_CHANNEL_SPLICE:
1386                 /*
1387                  * XXX: The lttng-modules splice "actor" does not handle copying
1388                  * partial pages hence only using the subbuffer size without the
1389                  * padding makes the splice fail.
1390                  */
1391                 subbuf_size = len;
1392                 padding = 0;
1393
1394                 /* splice the subbuffer to the tracefile */
1395                 ret = lttng_consumer_on_read_subbuffer_splice(ctx, stream, subbuf_size,
1396                                 padding, &index);
1397                 /*
1398                  * XXX: Splice does not support network streaming so the return value
1399                  * is simply checked against subbuf_size and not like the mmap() op.
1400                  */
1401                 if (ret != subbuf_size) {
1402                         /*
1403                          * display the error but continue processing to try
1404                          * to release the subbuffer
1405                          */
1406                         ERR("Error splicing to tracefile (ret: %zd != len: %lu)",
1407                                         ret, subbuf_size);
1408                         write_index = 0;
1409                 }
1410                 break;
1411         case CONSUMER_CHANNEL_MMAP:
1412                 /* Get subbuffer size without padding */
1413                 err = kernctl_get_subbuf_size(infd, &subbuf_size);
1414                 if (err != 0) {
1415                         PERROR("Getting sub-buffer len failed.");
1416                         err = kernctl_put_subbuf(infd);
1417                         if (err != 0) {
1418                                 if (errno == EFAULT) {
1419                                         PERROR("Error in unreserving sub buffer\n");
1420                                 } else if (errno == EIO) {
1421                                         /* Should never happen with newer LTTng versions */
1422                                         PERROR("Reader has been pushed by the writer, last sub-buffer corrupted.");
1423                                 }
1424                                 ret = -errno;
1425                                 goto end;
1426                         }
1427                         ret = -errno;
1428                         goto end;
1429                 }
1430
1431                 /* Make sure the tracer is not gone mad on us! */
1432                 assert(len >= subbuf_size);
1433
1434                 padding = len - subbuf_size;
1435
1436                 /* write the subbuffer to the tracefile */
1437                 ret = lttng_consumer_on_read_subbuffer_mmap(ctx, stream, subbuf_size,
1438                                 padding, &index);
1439                 /*
1440                  * The mmap operation should write subbuf_size amount of data when
1441                  * network streaming or the full padding (len) size when we are _not_
1442                  * streaming.
1443                  */
1444                 if ((ret != subbuf_size && stream->net_seq_idx != (uint64_t) -1ULL) ||
1445                                 (ret != len && stream->net_seq_idx == (uint64_t) -1ULL)) {
1446                         /*
1447                          * Display the error but continue processing to try to release the
1448                          * subbuffer. This is a DBG statement since this is possible to
1449                          * happen without being a critical error.
1450                          */
1451                         DBG("Error writing to tracefile "
1452                                         "(ret: %zd != len: %lu != subbuf_size: %lu)",
1453                                         ret, len, subbuf_size);
1454                         write_index = 0;
1455                 }
1456                 break;
1457         default:
1458                 ERR("Unknown output method");
1459                 ret = -EPERM;
1460         }
1461
1462         err = kernctl_put_next_subbuf(infd);
1463         if (err != 0) {
1464                 if (errno == EFAULT) {
1465                         PERROR("Error in unreserving sub buffer\n");
1466                 } else if (errno == EIO) {
1467                         /* Should never happen with newer LTTng versions */
1468                         PERROR("Reader has been pushed by the writer, last sub-buffer corrupted.");
1469                 }
1470                 ret = -errno;
1471                 goto end;
1472         }
1473
1474         /* Write index if needed. */
1475         if (!write_index) {
1476                 goto end;
1477         }
1478
1479         if (stream->chan->live_timer_interval && !stream->metadata_flag) {
1480                 /*
1481                  * In live, block until all the metadata is sent.
1482                  */
1483                 pthread_mutex_lock(&stream->metadata_timer_lock);
1484                 assert(!stream->missed_metadata_flush);
1485                 stream->waiting_on_metadata = true;
1486                 pthread_mutex_unlock(&stream->metadata_timer_lock);
1487
1488                 err = consumer_stream_sync_metadata(ctx, stream->session_id);
1489
1490                 pthread_mutex_lock(&stream->metadata_timer_lock);
1491                 stream->waiting_on_metadata = false;
1492                 if (stream->missed_metadata_flush) {
1493                         stream->missed_metadata_flush = false;
1494                         pthread_mutex_unlock(&stream->metadata_timer_lock);
1495                         (void) consumer_flush_kernel_index(stream);
1496                 } else {
1497                         pthread_mutex_unlock(&stream->metadata_timer_lock);
1498                 }
1499                 if (err < 0) {
1500                         goto end;
1501                 }
1502         }
1503
1504         err = consumer_stream_write_index(stream, &index);
1505         if (err < 0) {
1506                 goto end;
1507         }
1508
1509 end:
1510         return ret;
1511 }
1512
1513 int lttng_kconsumer_on_recv_stream(struct lttng_consumer_stream *stream)
1514 {
1515         int ret;
1516
1517         assert(stream);
1518
1519         /*
1520          * Don't create anything if this is set for streaming or should not be
1521          * monitored.
1522          */
1523         if (stream->net_seq_idx == (uint64_t) -1ULL && stream->chan->monitor) {
1524                 ret = utils_create_stream_file(stream->chan->pathname, stream->name,
1525                                 stream->chan->tracefile_size, stream->tracefile_count_current,
1526                                 stream->uid, stream->gid, NULL);
1527                 if (ret < 0) {
1528                         goto error;
1529                 }
1530                 stream->out_fd = ret;
1531                 stream->tracefile_size_current = 0;
1532
1533                 if (!stream->metadata_flag) {
1534                         struct lttng_index_file *index_file;
1535
1536                         index_file = lttng_index_file_create(stream->chan->pathname,
1537                                         stream->name, stream->uid, stream->gid,
1538                                         stream->chan->tracefile_size,
1539                                         stream->tracefile_count_current,
1540                                         CTF_INDEX_MAJOR, CTF_INDEX_MINOR);
1541                         if (!index_file) {
1542                                 goto error;
1543                         }
1544                         stream->index_file = index_file;
1545                 }
1546         }
1547
1548         if (stream->output == LTTNG_EVENT_MMAP) {
1549                 /* get the len of the mmap region */
1550                 unsigned long mmap_len;
1551
1552                 ret = kernctl_get_mmap_len(stream->wait_fd, &mmap_len);
1553                 if (ret != 0) {
1554                         PERROR("kernctl_get_mmap_len");
1555                         ret = -errno;
1556                         goto error_close_fd;
1557                 }
1558                 stream->mmap_len = (size_t) mmap_len;
1559
1560                 stream->mmap_base = mmap(NULL, stream->mmap_len, PROT_READ,
1561                                 MAP_PRIVATE, stream->wait_fd, 0);
1562                 if (stream->mmap_base == MAP_FAILED) {
1563                         PERROR("Error mmaping");
1564                         ret = -1;
1565                         goto error_close_fd;
1566                 }
1567         }
1568
1569         /* we return 0 to let the library handle the FD internally */
1570         return 0;
1571
1572 error_close_fd:
1573         if (stream->out_fd >= 0) {
1574                 int err;
1575
1576                 err = close(stream->out_fd);
1577                 assert(!err);
1578                 stream->out_fd = -1;
1579         }
1580 error:
1581         return ret;
1582 }
1583
1584 /*
1585  * Check if data is still being extracted from the buffers for a specific
1586  * stream. Consumer data lock MUST be acquired before calling this function
1587  * and the stream lock.
1588  *
1589  * Return 1 if the traced data are still getting read else 0 meaning that the
1590  * data is available for trace viewer reading.
1591  */
1592 int lttng_kconsumer_data_pending(struct lttng_consumer_stream *stream)
1593 {
1594         int ret;
1595
1596         assert(stream);
1597
1598         if (stream->endpoint_status != CONSUMER_ENDPOINT_ACTIVE) {
1599                 ret = 0;
1600                 goto end;
1601         }
1602
1603         ret = kernctl_get_next_subbuf(stream->wait_fd);
1604         if (ret == 0) {
1605                 /* There is still data so let's put back this subbuffer. */
1606                 ret = kernctl_put_subbuf(stream->wait_fd);
1607                 assert(ret == 0);
1608                 ret = 1;   /* Data is pending */
1609                 goto end;
1610         }
1611
1612         /* Data is NOT pending and ready to be read. */
1613         ret = 0;
1614
1615 end:
1616         return ret;
1617 }