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                 unsigned long consumed_pos, produced_pos;
 144
 145                 health_code_update();
 146
 147                 /*
 148                  * Lock stream because we are about to change its state.
 149                  */
 150                 pthread_mutex_lock(&stream->lock);
 151
 152                 /*
 153                  * Assign the received relayd ID so we can use it for streaming. The streams
 154                  * are not visible to anyone so this is OK to change it.
 155                  */
 156                 stream->net_seq_idx = relayd_id;
 157                 channel->relayd_id = relayd_id;
 158                 if (relayd_id != (uint64_t) -1ULL) {
 159                         ret = consumer_send_relayd_stream(stream, path);
 160                         if (ret < 0) {
 161                                 ERR("sending stream to relayd");
 162                                 goto end_unlock;
 163                         }
 164                 } else {
 165                         ret = utils_create_stream_file(path, stream->name,
 166                                         stream->chan->tracefile_size,
 167                                         stream->tracefile_count_current,
 168                                         stream->uid, stream->gid, NULL);
 169                         if (ret < 0) {
 170                                 ERR("utils_create_stream_file");
 171                                 goto end_unlock;
 172                         }
 173
 174                         stream->out_fd = ret;
 175                         stream->tracefile_size_current = 0;
 176
 177                         DBG("Kernel consumer snapshot stream %s/%s (%" PRIu64 ")",
 178                                         path, stream->name, stream->key);
 179                 }
 180                 if (relayd_id != -1ULL) {
 181                         ret = consumer_send_relayd_streams_sent(relayd_id);
 182                         if (ret < 0) {
 183                                 ERR("sending streams sent to relayd");
 184                                 goto end_unlock;
 185                         }
 186                         channel->streams_sent_to_relayd = true;
 187                 }
 188
 189                 ret = kernctl_buffer_flush_empty(stream->wait_fd);
 190                 if (ret < 0) {
 191                         /*
 192                          * Doing a buffer flush which does not take into
 193                          * account empty packets. This is not perfect
 194                          * for stream intersection, but required as a
 195                          * fall-back when "flush_empty" is not
 196                          * implemented by lttng-modules.
 197                          */
 198                         ret = kernctl_buffer_flush(stream->wait_fd);
 199                         if (ret < 0) {
 200                                 ERR("Failed to flush kernel stream");
 201                                 goto end_unlock;
 202                         }
 203                 }
 204
 205                 ret = lttng_kconsumer_take_snapshot(stream);
 206                 if (ret < 0) {
 207                         ERR("Taking kernel snapshot");
 208                         goto end_unlock;
 209                 }
 210
 211                 ret = lttng_kconsumer_get_produced_snapshot(stream, &produced_pos);
 212                 if (ret < 0) {
 213                         ERR("Produced kernel snapshot position");
 214                         goto end_unlock;
 215                 }
 216
 217                 ret = lttng_kconsumer_get_consumed_snapshot(stream, &consumed_pos);
 218                 if (ret < 0) {
 219                         ERR("Consumerd kernel snapshot position");
 220                         goto end_unlock;
 221                 }
 222
 223                 if (stream->max_sb_size == 0) {
 224                         ret = kernctl_get_max_subbuf_size(stream->wait_fd,
 225                                         &stream->max_sb_size);
 226                         if (ret < 0) {
 227                                 ERR("Getting kernel max_sb_size");
 228                                 ret = -errno;
 229                                 goto end_unlock;
 230                         }
 231                 }
 232
 233                 consumed_pos = consumer_get_consume_start_pos(consumed_pos,
 234                                 produced_pos, nb_packets_per_stream,
 235                                 stream->max_sb_size);
 236
 237                 while (consumed_pos < produced_pos) {
 238                         ssize_t read_len;
 239                         unsigned long len, padded_len;
 240
 241                         health_code_update();
 242
 243                         DBG("Kernel consumer taking snapshot at pos %lu", consumed_pos);
 244
 245                         ret = kernctl_get_subbuf(stream->wait_fd, &consumed_pos);
 246                         if (ret < 0) {
 247                                 if (errno != EAGAIN) {
 248                                         PERROR("kernctl_get_subbuf snapshot");
 249                                         ret = -errno;
 250                                         goto end_unlock;
 251                                 }
 252                                 DBG("Kernel consumer get subbuf failed. Skipping it.");
 253                                 consumed_pos += stream->max_sb_size;
 254                                 stream->chan->lost_packets++;
 255                                 continue;
 256                         }
 257
 258                         ret = kernctl_get_subbuf_size(stream->wait_fd, &len);
 259                         if (ret < 0) {
 260                                 ERR("Snapshot kernctl_get_subbuf_size");
 261                                 ret = -errno;
 262                                 goto error_put_subbuf;
 263                         }
 264
 265                         ret = kernctl_get_padded_subbuf_size(stream->wait_fd, &padded_len);
 266                         if (ret < 0) {
 267                                 ERR("Snapshot kernctl_get_padded_subbuf_size");
 268                                 ret = -errno;
 269                                 goto error_put_subbuf;
 270                         }
 271
 272                         read_len = lttng_consumer_on_read_subbuffer_mmap(ctx, stream, len,
 273                                         padded_len - len, NULL);
 274                         /*
 275                          * We write the padded len in local tracefiles but the data len
 276                          * when using a relay. Display the error but continue processing
 277                          * to try to release the subbuffer.
 278                          */
 279                         if (relayd_id != (uint64_t) -1ULL) {
 280                                 if (read_len != len) {
 281                                         ERR("Error sending to the relay (ret: %zd != len: %lu)",
 282                                                         read_len, len);
 283                                 }
 284                         } else {
 285                                 if (read_len != padded_len) {
 286                                         ERR("Error writing to tracefile (ret: %zd != len: %lu)",
 287                                                         read_len, padded_len);
 288                                 }
 289                         }
 290
 291                         ret = kernctl_put_subbuf(stream->wait_fd);
 292                         if (ret < 0) {
 293                                 ERR("Snapshot kernctl_put_subbuf");
 294                                 ret = -errno;
 295                                 goto end_unlock;
 296                         }
 297                         consumed_pos += stream->max_sb_size;
 298                 }
 299
 300                 if (relayd_id == (uint64_t) -1ULL) {
 301                         if (stream->out_fd >= 0) {
 302                                 ret = close(stream->out_fd);
 303                                 if (ret < 0) {
 304                                         PERROR("Kernel consumer snapshot close out_fd");
 305                                         goto end_unlock;
 306                                 }
 307                                 stream->out_fd = -1;
 308                         }
 309                 } else {
 310                         close_relayd_stream(stream);
 311                         stream->net_seq_idx = (uint64_t) -1ULL;
 312                 }
 313                 pthread_mutex_unlock(&stream->lock);
 314         }
 315
 316         /* All good! */
 317         ret = 0;
 318         goto end;
 319
 320 error_put_subbuf:
 321         ret = kernctl_put_subbuf(stream->wait_fd);
 322         if (ret < 0) {
 323                 ret = -errno;
 324                 ERR("Snapshot kernctl_put_subbuf error path");
 325         }
 326 end_unlock:
 327         pthread_mutex_unlock(&stream->lock);
 328 end:
 329         rcu_read_unlock();
 330         return ret;
 331 }
 332
 333 /*
 334  * Read the whole metadata available for a snapshot.
 335  *
 336  * Returns 0 on success, < 0 on error
 337  */
 338 int lttng_kconsumer_snapshot_metadata(uint64_t key, char *path,
 339                 uint64_t relayd_id, struct lttng_consumer_local_data *ctx)
 340 {
 341         int ret, use_relayd = 0;
 342         ssize_t ret_read;
 343         struct lttng_consumer_channel *metadata_channel;
 344         struct lttng_consumer_stream *metadata_stream;
 345
 346         assert(ctx);
 347
 348         DBG("Kernel consumer snapshot metadata with key %" PRIu64 " at path %s",
 349                         key, path);
 350
 351         rcu_read_lock();
 352
 353         metadata_channel = consumer_find_channel(key);
 354         if (!metadata_channel) {
 355                 ERR("Kernel snapshot metadata not found for key %" PRIu64, key);
 356                 ret = -1;
 357                 goto error;
 358         }
 359
 360         metadata_stream = metadata_channel->metadata_stream;
 361         assert(metadata_stream);
 362
 363         /* Flag once that we have a valid relayd for the stream. */
 364         if (relayd_id != (uint64_t) -1ULL) {
 365                 use_relayd = 1;
 366         }
 367
 368         if (use_relayd) {
 369                 ret = consumer_send_relayd_stream(metadata_stream, path);
 370                 if (ret < 0) {
 371                         goto error;
 372                 }
 373         } else {
 374                 ret = utils_create_stream_file(path, metadata_stream->name,
 375                                 metadata_stream->chan->tracefile_size,
 376                                 metadata_stream->tracefile_count_current,
 377                                 metadata_stream->uid, metadata_stream->gid, NULL);
 378                 if (ret < 0) {
 379                         goto error;
 380                 }
 381                 metadata_stream->out_fd = ret;
 382         }
 383
 384         do {
 385                 health_code_update();
 386
 387                 ret_read = lttng_kconsumer_read_subbuffer(metadata_stream, ctx);
 388                 if (ret_read < 0) {
 389                         if (ret_read != -EAGAIN) {
 390                                 ERR("Kernel snapshot reading metadata subbuffer (ret: %zd)",
 391                                                 ret_read);
 392                                 goto error;
 393                         }
 394                         /* ret_read is negative at this point so we will exit the loop. */
 395                         continue;
 396                 }
 397         } while (ret_read >= 0);
 398
 399         if (use_relayd) {
 400                 close_relayd_stream(metadata_stream);
 401                 metadata_stream->net_seq_idx = (uint64_t) -1ULL;
 402         } else {
 403                 if (metadata_stream->out_fd >= 0) {
 404                         ret = close(metadata_stream->out_fd);
 405                         if (ret < 0) {
 406                                 PERROR("Kernel consumer snapshot metadata close out_fd");
 407                                 /*
 408                                  * Don't go on error here since the snapshot was successful at this
 409                                  * point but somehow the close failed.
 410                                  */
 411                         }
 412                         metadata_stream->out_fd = -1;
 413                 }
 414         }
 415
 416         ret = 0;
 417
 418         cds_list_del(&metadata_stream->send_node);
 419         consumer_stream_destroy(metadata_stream, NULL);
 420         metadata_channel->metadata_stream = NULL;
 421 error:
 422         rcu_read_unlock();
 423         return ret;
 424 }
 425
 426 /*
 427  * Receive command from session daemon and process it.
 428  *
 429  * Return 1 on success else a negative value or 0.
 430  */
 431 int lttng_kconsumer_recv_cmd(struct lttng_consumer_local_data *ctx,
 432                 int sock, struct pollfd *consumer_sockpoll)
 433 {
 434         ssize_t ret;
 435         enum lttcomm_return_code ret_code = LTTCOMM_CONSUMERD_SUCCESS;
 436         struct lttcomm_consumer_msg msg;
 437
 438         health_code_update();
 439
 440         ret = lttcomm_recv_unix_sock(sock, &msg, sizeof(msg));
 441         if (ret != sizeof(msg)) {
 442                 if (ret > 0) {
 443                         lttng_consumer_send_error(ctx, LTTCOMM_CONSUMERD_ERROR_RECV_CMD);
 444                         ret = -1;
 445                 }
 446                 return ret;
 447         }
 448
 449         health_code_update();
 450
 451         /* Deprecated command */
 452         assert(msg.cmd_type != LTTNG_CONSUMER_STOP);
 453
 454         health_code_update();
 455
 456         /* relayd needs RCU read-side protection */
 457         rcu_read_lock();
 458
 459         switch (msg.cmd_type) {
 460         case LTTNG_CONSUMER_ADD_RELAYD_SOCKET:
 461         {
 462                 /* Session daemon status message are handled in the following call. */
 463                 ret = consumer_add_relayd_socket(msg.u.relayd_sock.net_index,
 464                                 msg.u.relayd_sock.type, ctx, sock, consumer_sockpoll,
 465                                 &msg.u.relayd_sock.sock, msg.u.relayd_sock.session_id,
 466                                  msg.u.relayd_sock.relayd_session_id);
 467                 goto end_nosignal;
 468         }
 469         case LTTNG_CONSUMER_ADD_CHANNEL:
 470         {
 471                 struct lttng_consumer_channel *new_channel;
 472                 int ret_recv;
 473
 474                 health_code_update();
 475
 476                 /* First send a status message before receiving the fds. */
 477                 ret = consumer_send_status_msg(sock, ret_code);
 478                 if (ret < 0) {
 479                         /* Somehow, the session daemon is not responding anymore. */
 480                         goto error_fatal;
 481                 }
 482
 483                 health_code_update();
 484
 485                 DBG("consumer_add_channel %" PRIu64, msg.u.channel.channel_key);
 486                 new_channel = consumer_allocate_channel(msg.u.channel.channel_key,
 487                                 msg.u.channel.session_id, msg.u.channel.pathname,
 488                                 msg.u.channel.name, msg.u.channel.uid, msg.u.channel.gid,
 489                                 msg.u.channel.relayd_id, msg.u.channel.output,
 490                                 msg.u.channel.tracefile_size,
 491                                 msg.u.channel.tracefile_count, 0,
 492                                 msg.u.channel.monitor,
 493                                 msg.u.channel.live_timer_interval,
 494                                 NULL, NULL);
 495                 if (new_channel == NULL) {
 496                         lttng_consumer_send_error(ctx, LTTCOMM_CONSUMERD_OUTFD_ERROR);
 497                         goto end_nosignal;
 498                 }
 499                 new_channel->nb_init_stream_left = msg.u.channel.nb_init_streams;
 500                 switch (msg.u.channel.output) {
 501                 case LTTNG_EVENT_SPLICE:
 502                         new_channel->output = CONSUMER_CHANNEL_SPLICE;
 503                         break;
 504                 case LTTNG_EVENT_MMAP:
 505                         new_channel->output = CONSUMER_CHANNEL_MMAP;
 506                         break;
 507                 default:
 508                         ERR("Channel output unknown %d", msg.u.channel.output);
 509                         goto end_nosignal;
 510                 }
 511
 512                 /* Translate and save channel type. */
 513                 switch (msg.u.channel.type) {
 514                 case CONSUMER_CHANNEL_TYPE_DATA:
 515                 case CONSUMER_CHANNEL_TYPE_METADATA:
 516                         new_channel->type = msg.u.channel.type;
 517                         break;
 518                 default:
 519                         assert(0);
 520                         goto end_nosignal;
 521                 };
 522
 523                 health_code_update();
 524
 525                 if (ctx->on_recv_channel != NULL) {
 526                         ret_recv = ctx->on_recv_channel(new_channel);
 527                         if (ret_recv == 0) {
 528                                 ret = consumer_add_channel(new_channel, ctx);
 529                         } else if (ret_recv < 0) {
 530                                 goto end_nosignal;
 531                         }
 532                 } else {
 533                         ret = consumer_add_channel(new_channel, ctx);
 534                 }
 535                 if (CONSUMER_CHANNEL_TYPE_DATA) {
 536                         consumer_timer_live_start(new_channel,
 537                                         msg.u.channel.live_timer_interval);
 538                 }
 539
 540                 health_code_update();
 541
 542                 /* If we received an error in add_channel, we need to report it. */
 543                 if (ret < 0) {
 544                         ret = consumer_send_status_msg(sock, ret);
 545                         if (ret < 0) {
 546                                 goto error_fatal;
 547                         }
 548                         goto end_nosignal;
 549                 }
 550
 551                 goto end_nosignal;
 552         }
 553         case LTTNG_CONSUMER_ADD_STREAM:
 554         {
 555                 int fd;
 556                 struct lttng_pipe *stream_pipe;
 557                 struct lttng_consumer_stream *new_stream;
 558                 struct lttng_consumer_channel *channel;
 559                 int alloc_ret = 0;
 560
 561                 /*
 562                  * Get stream's channel reference. Needed when adding the stream to the
 563                  * global hash table.
 564                  */
 565                 channel = consumer_find_channel(msg.u.stream.channel_key);
 566                 if (!channel) {
 567                         /*
 568                          * We could not find the channel. Can happen if cpu hotplug
 569                          * happens while tearing down.
 570                          */
 571                         ERR("Unable to find channel key %" PRIu64, msg.u.stream.channel_key);
 572                         ret_code = LTTCOMM_CONSUMERD_CHAN_NOT_FOUND;
 573                 }
 574
 575                 health_code_update();
 576
 577                 /* First send a status message before receiving the fds. */
 578                 ret = consumer_send_status_msg(sock, ret_code);
 579                 if (ret < 0) {
 580                         /* Somehow, the session daemon is not responding anymore. */
 581                         goto error_fatal;
 582                 }
 583
 584                 health_code_update();
 585
 586                 if (ret_code != LTTCOMM_CONSUMERD_SUCCESS) {
 587                         /* Channel was not found. */
 588                         goto end_nosignal;
 589                 }
 590
 591                 /* Blocking call */
 592                 health_poll_entry();
 593                 ret = lttng_consumer_poll_socket(consumer_sockpoll);
 594                 health_poll_exit();
 595                 if (ret) {
 596                         goto error_fatal;
 597                 }
 598
 599                 health_code_update();
 600
 601                 /* Get stream file descriptor from socket */
 602                 ret = lttcomm_recv_fds_unix_sock(sock, &fd, 1);
 603                 if (ret != sizeof(fd)) {
 604                         lttng_consumer_send_error(ctx, LTTCOMM_CONSUMERD_ERROR_RECV_FD);
 605                         rcu_read_unlock();
 606                         return ret;
 607                 }
 608
 609                 health_code_update();
 610
 611                 /*
 612                  * Send status code to session daemon only if the recv works. If the
 613                  * above recv() failed, the session daemon is notified through the
 614                  * error socket and the teardown is eventually done.
 615                  */
 616                 ret = consumer_send_status_msg(sock, ret_code);
 617                 if (ret < 0) {
 618                         /* Somehow, the session daemon is not responding anymore. */
 619                         goto end_nosignal;
 620                 }
 621
 622                 health_code_update();
 623
 624                 new_stream = consumer_allocate_stream(channel->key,
 625                                 fd,
 626                                 LTTNG_CONSUMER_ACTIVE_STREAM,
 627                                 channel->name,
 628                                 channel->uid,
 629                                 channel->gid,
 630                                 channel->relayd_id,
 631                                 channel->session_id,
 632                                 msg.u.stream.cpu,
 633                                 &alloc_ret,
 634                                 channel->type,
 635                                 channel->monitor);
 636                 if (new_stream == NULL) {
 637                         switch (alloc_ret) {
 638                         case -ENOMEM:
 639                         case -EINVAL:
 640                         default:
 641                                 lttng_consumer_send_error(ctx, LTTCOMM_CONSUMERD_OUTFD_ERROR);
 642                                 break;
 643                         }
 644                         goto end_nosignal;
 645                 }
 646
 647                 new_stream->chan = channel;
 648                 new_stream->wait_fd = fd;
 649                 switch (channel->output) {
 650                 case CONSUMER_CHANNEL_SPLICE:
 651                         new_stream->output = LTTNG_EVENT_SPLICE;
 652                         ret = utils_create_pipe(new_stream->splice_pipe);
 653                         if (ret < 0) {
 654                                 goto end_nosignal;
 655                         }
 656                         break;
 657                 case CONSUMER_CHANNEL_MMAP:
 658                         new_stream->output = LTTNG_EVENT_MMAP;
 659                         break;
 660                 default:
 661                         ERR("Stream output unknown %d", channel->output);
 662                         goto end_nosignal;
 663                 }
 664
 665                 /*
 666                  * We've just assigned the channel to the stream so increment the
 667                  * refcount right now. We don't need to increment the refcount for
 668                  * streams in no monitor because we handle manually the cleanup of
 669                  * those. It is very important to make sure there is NO prior
 670                  * consumer_del_stream() calls or else the refcount will be unbalanced.
 671                  */
 672                 if (channel->monitor) {
 673                         uatomic_inc(&new_stream->chan->refcount);
 674                 }
 675
 676                 /*
 677                  * The buffer flush is done on the session daemon side for the kernel
 678                  * so no need for the stream "hangup_flush_done" variable to be
 679                  * tracked. This is important for a kernel stream since we don't rely
 680                  * on the flush state of the stream to read data. It's not the case for
 681                  * user space tracing.
 682                  */
 683                 new_stream->hangup_flush_done = 0;
 684
 685                 health_code_update();
 686
 687                 if (ctx->on_recv_stream) {
 688                         ret = ctx->on_recv_stream(new_stream);
 689                         if (ret < 0) {
 690                                 consumer_stream_free(new_stream);
 691                                 goto end_nosignal;
 692                         }
 693                 }
 694
 695                 health_code_update();
 696
 697                 if (new_stream->metadata_flag) {
 698                         channel->metadata_stream = new_stream;
 699                 }
 700
 701                 /* Do not monitor this stream. */
 702                 if (!channel->monitor) {
 703                         DBG("Kernel consumer add stream %s in no monitor mode with "
 704                                         "relayd id %" PRIu64, new_stream->name,
 705                                         new_stream->net_seq_idx);
 706                         cds_list_add(&new_stream->send_node, &channel->streams.head);
 707                         break;
 708                 }
 709
 710                 /* Send stream to relayd if the stream has an ID. */
 711                 if (new_stream->net_seq_idx != (uint64_t) -1ULL) {
 712                         ret = consumer_send_relayd_stream(new_stream,
 713                                         new_stream->chan->pathname);
 714                         if (ret < 0) {
 715                                 consumer_stream_free(new_stream);
 716                                 goto end_nosignal;
 717                         }
 718
 719                         /*
 720                          * If adding an extra stream to an already
 721                          * existing channel (e.g. cpu hotplug), we need
 722                          * to send the "streams_sent" command to relayd.
 723                          */
 724                         if (channel->streams_sent_to_relayd) {
 725                                 ret = consumer_send_relayd_streams_sent(
 726                                                 new_stream->net_seq_idx);
 727                                 if (ret < 0) {
 728                                         goto end_nosignal;
 729                                 }
 730                         }
 731                 }
 732
 733                 /* Get the right pipe where the stream will be sent. */
 734                 if (new_stream->metadata_flag) {
 735                         ret = consumer_add_metadata_stream(new_stream);
 736                         if (ret) {
 737                                 ERR("Consumer add metadata stream %" PRIu64 " failed. Continuing",
 738                                                 new_stream->key);
 739                                 consumer_stream_free(new_stream);
 740                                 goto end_nosignal;
 741                         }
 742                         stream_pipe = ctx->consumer_metadata_pipe;
 743                 } else {
 744                         ret = consumer_add_data_stream(new_stream);
 745                         if (ret) {
 746                                 ERR("Consumer add stream %" PRIu64 " failed. Continuing",
 747                                                 new_stream->key);
 748                                 consumer_stream_free(new_stream);
 749                                 goto end_nosignal;
 750                         }
 751                         stream_pipe = ctx->consumer_data_pipe;
 752                 }
 753
 754                 /* Vitible to other threads */
 755                 new_stream->globally_visible = 1;
 756
 757                 health_code_update();
 758
 759                 ret = lttng_pipe_write(stream_pipe, &new_stream, sizeof(new_stream));
 760                 if (ret < 0) {
 761                         ERR("Consumer write %s stream to pipe %d",
 762                                         new_stream->metadata_flag ? "metadata" : "data",
 763                                         lttng_pipe_get_writefd(stream_pipe));
 764                         if (new_stream->metadata_flag) {
 765                                 consumer_del_stream_for_metadata(new_stream);
 766                         } else {
 767                                 consumer_del_stream_for_data(new_stream);
 768                         }
 769                         goto end_nosignal;
 770                 }
 771
 772                 DBG("Kernel consumer ADD_STREAM %s (fd: %d) with relayd id %" PRIu64,
 773                                 new_stream->name, fd, new_stream->relayd_stream_id);
 774                 break;
 775         }
 776         case LTTNG_CONSUMER_STREAMS_SENT:
 777         {
 778                 struct lttng_consumer_channel *channel;
 779
 780                 /*
 781                  * Get stream's channel reference. Needed when adding the stream to the
 782                  * global hash table.
 783                  */
 784                 channel = consumer_find_channel(msg.u.sent_streams.channel_key);
 785                 if (!channel) {
 786                         /*
 787                          * We could not find the channel. Can happen if cpu hotplug
 788                          * happens while tearing down.
 789                          */
 790                         ERR("Unable to find channel key %" PRIu64,
 791                                         msg.u.sent_streams.channel_key);
 792                         ret_code = LTTCOMM_CONSUMERD_CHAN_NOT_FOUND;
 793                 }
 794
 795                 health_code_update();
 796
 797                 /*
 798                  * Send status code to session daemon.
 799                  */
 800                 ret = consumer_send_status_msg(sock, ret_code);
 801                 if (ret < 0 || ret_code != LTTCOMM_CONSUMERD_SUCCESS) {
 802                         /* Somehow, the session daemon is not responding anymore. */
 803                         goto end_nosignal;
 804                 }
 805
 806                 health_code_update();
 807
 808                 /*
 809                  * We should not send this message if we don't monitor the
 810                  * streams in this channel.
 811                  */
 812                 if (!channel->monitor) {
 813                         break;
 814                 }
 815
 816                 health_code_update();
 817                 /* Send stream to relayd if the stream has an ID. */
 818                 if (msg.u.sent_streams.net_seq_idx != (uint64_t) -1ULL) {
 819                         ret = consumer_send_relayd_streams_sent(
 820                                         msg.u.sent_streams.net_seq_idx);
 821                         if (ret < 0) {
 822                                 goto end_nosignal;
 823                         }
 824                         channel->streams_sent_to_relayd = true;
 825                 }
 826                 break;
 827         }
 828         case LTTNG_CONSUMER_UPDATE_STREAM:
 829         {
 830                 rcu_read_unlock();
 831                 return -ENOSYS;
 832         }
 833         case LTTNG_CONSUMER_DESTROY_RELAYD:
 834         {
 835                 uint64_t index = msg.u.destroy_relayd.net_seq_idx;
 836                 struct consumer_relayd_sock_pair *relayd;
 837
 838                 DBG("Kernel consumer destroying relayd %" PRIu64, index);
 839
 840                 /* Get relayd reference if exists. */
 841                 relayd = consumer_find_relayd(index);
 842                 if (relayd == NULL) {
 843                         DBG("Unable to find relayd %" PRIu64, index);
 844                         ret_code = LTTCOMM_CONSUMERD_RELAYD_FAIL;
 845                 }
 846
 847                 /*
 848                  * Each relayd socket pair has a refcount of stream attached to it
 849                  * which tells if the relayd is still active or not depending on the
 850                  * refcount value.
 851                  *
 852                  * This will set the destroy flag of the relayd object and destroy it
 853                  * if the refcount reaches zero when called.
 854                  *
 855                  * The destroy can happen either here or when a stream fd hangs up.
 856                  */
 857                 if (relayd) {
 858                         consumer_flag_relayd_for_destroy(relayd);
 859                 }
 860
 861                 health_code_update();
 862
 863                 ret = consumer_send_status_msg(sock, ret_code);
 864                 if (ret < 0) {
 865                         /* Somehow, the session daemon is not responding anymore. */
 866                         goto error_fatal;
 867                 }
 868
 869                 goto end_nosignal;
 870         }
 871         case LTTNG_CONSUMER_DATA_PENDING:
 872         {
 873                 int32_t ret;
 874                 uint64_t id = msg.u.data_pending.session_id;
 875
 876                 DBG("Kernel consumer data pending command for id %" PRIu64, id);
 877
 878                 ret = consumer_data_pending(id);
 879
 880                 health_code_update();
 881
 882                 /* Send back returned value to session daemon */
 883                 ret = lttcomm_send_unix_sock(sock, &ret, sizeof(ret));
 884                 if (ret < 0) {
 885                         PERROR("send data pending ret code");
 886                         goto error_fatal;
 887                 }
 888
 889                 /*
 890                  * No need to send back a status message since the data pending
 891                  * returned value is the response.
 892                  */
 893                 break;
 894         }
 895         case LTTNG_CONSUMER_SNAPSHOT_CHANNEL:
 896         {
 897                 if (msg.u.snapshot_channel.metadata == 1) {
 898                         ret = lttng_kconsumer_snapshot_metadata(msg.u.snapshot_channel.key,
 899                                         msg.u.snapshot_channel.pathname,
 900                                         msg.u.snapshot_channel.relayd_id, ctx);
 901                         if (ret < 0) {
 902                                 ERR("Snapshot metadata failed");
 903                                 ret_code = LTTCOMM_CONSUMERD_ERROR_METADATA;
 904                         }
 905                 } else {
 906                         ret = lttng_kconsumer_snapshot_channel(msg.u.snapshot_channel.key,
 907                                         msg.u.snapshot_channel.pathname,
 908                                         msg.u.snapshot_channel.relayd_id,
 909                                         msg.u.snapshot_channel.nb_packets_per_stream,
 910                                         ctx);
 911                         if (ret < 0) {
 912                                 ERR("Snapshot channel failed");
 913                                 ret_code = LTTCOMM_CONSUMERD_CHAN_NOT_FOUND;
 914                         }
 915                 }
 916
 917                 health_code_update();
 918
 919                 ret = consumer_send_status_msg(sock, ret_code);
 920                 if (ret < 0) {
 921                         /* Somehow, the session daemon is not responding anymore. */
 922                         goto end_nosignal;
 923                 }
 924                 break;
 925         }
 926         case LTTNG_CONSUMER_DESTROY_CHANNEL:
 927         {
 928                 uint64_t key = msg.u.destroy_channel.key;
 929                 struct lttng_consumer_channel *channel;
 930
 931                 channel = consumer_find_channel(key);
 932                 if (!channel) {
 933                         ERR("Kernel consumer destroy channel %" PRIu64 " not found", key);
 934                         ret_code = LTTCOMM_CONSUMERD_CHAN_NOT_FOUND;
 935                 }
 936
 937                 health_code_update();
 938
 939                 ret = consumer_send_status_msg(sock, ret_code);
 940                 if (ret < 0) {
 941                         /* Somehow, the session daemon is not responding anymore. */
 942                         goto end_nosignal;
 943                 }
 944
 945                 health_code_update();
 946
 947                 /* Stop right now if no channel was found. */
 948                 if (!channel) {
 949                         goto end_nosignal;
 950                 }
 951
 952                 /*
 953                  * This command should ONLY be issued for channel with streams set in
 954                  * no monitor mode.
 955                  */
 956                 assert(!channel->monitor);
 957
 958                 /*
 959                  * The refcount should ALWAYS be 0 in the case of a channel in no
 960                  * monitor mode.
 961                  */
 962                 assert(!uatomic_sub_return(&channel->refcount, 1));
 963
 964                 consumer_del_channel(channel);
 965
 966                 goto end_nosignal;
 967         }
 968         case LTTNG_CONSUMER_DISCARDED_EVENTS:
 969         {
 970                 uint64_t ret;
 971                 struct lttng_consumer_channel *channel;
 972                 uint64_t id = msg.u.discarded_events.session_id;
 973                 uint64_t key = msg.u.discarded_events.channel_key;
 974
 975                 DBG("Kernel consumer discarded events command for session id %"
 976                                 PRIu64 ", channel key %" PRIu64, id, key);
 977
 978                 channel = consumer_find_channel(key);
 979                 if (!channel) {
 980                         ERR("Kernel consumer discarded events channel %"
 981                                         PRIu64 " not found", key);
 982                         ret = 0;
 983                 } else {
 984                         ret = channel->discarded_events;
 985                 }
 986
 987                 health_code_update();
 988
 989                 /* Send back returned value to session daemon */
 990                 ret = lttcomm_send_unix_sock(sock, &ret, sizeof(ret));
 991                 if (ret < 0) {
 992                         PERROR("send discarded events");
 993                         goto error_fatal;
 994                 }
 995
 996                 break;
 997         }
 998         case LTTNG_CONSUMER_LOST_PACKETS:
 999         {
1000                 uint64_t ret;
1001                 struct lttng_consumer_channel *channel;
1002                 uint64_t id = msg.u.lost_packets.session_id;
1003                 uint64_t key = msg.u.lost_packets.channel_key;
1004
1005                 DBG("Kernel consumer lost packets command for session id %"
1006                                 PRIu64 ", channel key %" PRIu64, id, key);
1007
1008                 channel = consumer_find_channel(key);
1009                 if (!channel) {
1010                         ERR("Kernel consumer lost packets channel %"
1011                                         PRIu64 " not found", key);
1012                         ret = 0;
1013                 } else {
1014                         ret = channel->lost_packets;
1015                 }
1016
1017                 health_code_update();
1018
1019                 /* Send back returned value to session daemon */
1020                 ret = lttcomm_send_unix_sock(sock, &ret, sizeof(ret));
1021                 if (ret < 0) {
1022                         PERROR("send lost packets");
1023                         goto error_fatal;
1024                 }
1025
1026                 break;
1027         }
1028         default:
1029                 goto end_nosignal;
1030         }
1031
1032 end_nosignal:
1033         rcu_read_unlock();
1034
1035         /*
1036          * Return 1 to indicate success since the 0 value can be a socket
1037          * shutdown during the recv() or send() call.
1038          */
1039         health_code_update();
1040         return 1;
1041
1042 error_fatal:
1043         rcu_read_unlock();
1044         /* This will issue a consumer stop. */
1045         return -1;
1046 }
1047
1048 /*
1049  * Populate index values of a kernel stream. Values are set in big endian order.
1050  *
1051  * Return 0 on success or else a negative value.
1052  */
1053 static int get_index_values(struct ctf_packet_index *index, int infd)
1054 {
1055         int ret;
1056
1057         ret = kernctl_get_timestamp_begin(infd, &index->timestamp_begin);
1058         if (ret < 0) {
1059                 PERROR("kernctl_get_timestamp_begin");
1060                 goto error;
1061         }
1062         index->timestamp_begin = htobe64(index->timestamp_begin);
1063
1064         ret = kernctl_get_timestamp_end(infd, &index->timestamp_end);
1065         if (ret < 0) {
1066                 PERROR("kernctl_get_timestamp_end");
1067                 goto error;
1068         }
1069         index->timestamp_end = htobe64(index->timestamp_end);
1070
1071         ret = kernctl_get_events_discarded(infd, &index->events_discarded);
1072         if (ret < 0) {
1073                 PERROR("kernctl_get_events_discarded");
1074                 goto error;
1075         }
1076         index->events_discarded = htobe64(index->events_discarded);
1077
1078         ret = kernctl_get_content_size(infd, &index->content_size);
1079         if (ret < 0) {
1080                 PERROR("kernctl_get_content_size");
1081                 goto error;
1082         }
1083         index->content_size = htobe64(index->content_size);
1084
1085         ret = kernctl_get_packet_size(infd, &index->packet_size);
1086         if (ret < 0) {
1087                 PERROR("kernctl_get_packet_size");
1088                 goto error;
1089         }
1090         index->packet_size = htobe64(index->packet_size);
1091
1092         ret = kernctl_get_stream_id(infd, &index->stream_id);
1093         if (ret < 0) {
1094                 PERROR("kernctl_get_stream_id");
1095                 goto error;
1096         }
1097         index->stream_id = htobe64(index->stream_id);
1098
1099         ret = kernctl_get_instance_id(infd, &index->stream_instance_id);
1100         if (ret < 0) {
1101                 if (ret == -ENOTTY) {
1102                         /* Command not implemented by lttng-modules. */
1103                         index->stream_instance_id = -1ULL;
1104                         ret = 0;
1105                 } else {
1106                         PERROR("kernctl_get_instance_id");
1107                         goto error;
1108                 }
1109         }
1110         index->stream_instance_id = htobe64(index->stream_instance_id);
1111
1112         ret = kernctl_get_sequence_number(infd, &index->packet_seq_num);
1113         if (ret < 0) {
1114                 if (ret == -ENOTTY) {
1115                         /* Command not implemented by lttng-modules. */
1116                         index->packet_seq_num = -1ULL;
1117                         ret = 0;
1118                 } else {
1119                         PERROR("kernctl_get_sequence_number");
1120                         goto error;
1121                 }
1122         }
1123         index->packet_seq_num = htobe64(index->packet_seq_num);
1124
1125 error:
1126         return ret;
1127 }
1128 /*
1129  * Sync metadata meaning request them to the session daemon and snapshot to the
1130  * metadata thread can consumer them.
1131  *
1132  * Metadata stream lock MUST be acquired.
1133  *
1134  * Return 0 if new metadatda is available, EAGAIN if the metadata stream
1135  * is empty or a negative value on error.
1136  */
1137 int lttng_kconsumer_sync_metadata(struct lttng_consumer_stream *metadata)
1138 {
1139         int ret;
1140
1141         assert(metadata);
1142
1143         ret = kernctl_buffer_flush(metadata->wait_fd);
1144         if (ret < 0) {
1145                 ERR("Failed to flush kernel stream");
1146                 goto end;
1147         }
1148
1149         ret = kernctl_snapshot(metadata->wait_fd);
1150         if (ret < 0) {
1151                 if (errno != EAGAIN) {
1152                         ERR("Sync metadata, taking kernel snapshot failed.");
1153                         goto end;
1154                 }
1155                 DBG("Sync metadata, no new kernel metadata");
1156                 /* No new metadata, exit. */
1157                 ret = ENODATA;
1158                 goto end;
1159         }
1160
1161 end:
1162         return ret;
1163 }
1164
1165 static
1166 int update_stream_stats(struct lttng_consumer_stream *stream)
1167 {
1168         int ret;
1169         uint64_t seq, discarded;
1170
1171         ret = kernctl_get_sequence_number(stream->wait_fd, &seq);
1172         if (ret < 0) {
1173                 if (ret == -ENOTTY) {
1174                         /* Command not implemented by lttng-modules. */
1175                         seq = -1ULL;
1176                         ret = 0;
1177                 } else {
1178                         PERROR("kernctl_get_sequence_number");
1179                         goto end;
1180                 }
1181         }
1182
1183         /*
1184          * Start the sequence when we extract the first packet in case we don't
1185          * start at 0 (for example if a consumer is not connected to the
1186          * session immediately after the beginning).
1187          */
1188         if (stream->last_sequence_number == -1ULL) {
1189                 stream->last_sequence_number = seq;
1190         } else if (seq > stream->last_sequence_number) {
1191                 stream->chan->lost_packets += seq -
1192                                 stream->last_sequence_number - 1;
1193         } else {
1194                 /* seq <= last_sequence_number */
1195                 ERR("Sequence number inconsistent : prev = %" PRIu64
1196                                 ", current = %" PRIu64,
1197                                 stream->last_sequence_number, seq);
1198                 ret = -1;
1199                 goto end;
1200         }
1201         stream->last_sequence_number = seq;
1202
1203         ret = kernctl_get_events_discarded(stream->wait_fd, &discarded);
1204         if (ret < 0) {
1205                 PERROR("kernctl_get_events_discarded");
1206                 goto end;
1207         }
1208         if (discarded < stream->last_discarded_events) {
1209                 /*
1210                  * Overflow has occurred. We assume only one wrap-around
1211                  * has occurred.
1212                  */
1213                 stream->chan->discarded_events += (1ULL << (CAA_BITS_PER_LONG - 1)) -
1214                         stream->last_discarded_events + discarded;
1215         } else {
1216                 stream->chan->discarded_events += discarded -
1217                         stream->last_discarded_events;
1218         }
1219         stream->last_discarded_events = discarded;
1220         ret = 0;
1221
1222 end:
1223         return ret;
1224 }
1225
1226 /*
1227  * Check if the local version of the metadata stream matches with the version
1228  * of the metadata stream in the kernel. If it was updated, set the reset flag
1229  * on the stream.
1230  */
1231 static
1232 int metadata_stream_check_version(int infd, struct lttng_consumer_stream *stream)
1233 {
1234         int ret;
1235         uint64_t cur_version;
1236
1237         ret = kernctl_get_metadata_version(infd, &cur_version);
1238         if (ret < 0) {
1239                 if (ret == -ENOTTY) {
1240                         /*
1241                          * LTTng-modules does not implement this
1242                          * command.
1243                          */
1244                         ret = 0;
1245                         goto end;
1246                 }
1247                 ERR("Failed to get the metadata version");
1248                 goto end;
1249         }
1250
1251         if (stream->metadata_version == cur_version) {
1252                 ret = 0;
1253                 goto end;
1254         }
1255
1256         DBG("New metadata version detected");
1257         stream->metadata_version = cur_version;
1258         stream->reset_metadata_flag = 1;
1259         ret = 0;
1260
1261 end:
1262         return ret;
1263 }
1264
1265 /*
1266  * Consume data on a file descriptor and write it on a trace file.
1267  */
1268 ssize_t lttng_kconsumer_read_subbuffer(struct lttng_consumer_stream *stream,
1269                 struct lttng_consumer_local_data *ctx)
1270 {
1271         unsigned long len, subbuf_size, padding;
1272         int err, write_index = 1;
1273         ssize_t ret = 0;
1274         int infd = stream->wait_fd;
1275         struct ctf_packet_index index;
1276
1277         DBG("In read_subbuffer (infd : %d)", infd);
1278
1279         /* Get the next subbuffer */
1280         err = kernctl_get_next_subbuf(infd);
1281         if (err != 0) {
1282                 /*
1283                  * This is a debug message even for single-threaded consumer,
1284                  * because poll() have more relaxed criterions than get subbuf,
1285                  * so get_subbuf may fail for short race windows where poll()
1286                  * would issue wakeups.
1287                  */
1288                 DBG("Reserving sub buffer failed (everything is normal, "
1289                                 "it is due to concurrency)");
1290                 ret = -errno;
1291                 goto end;
1292         }
1293
1294         /* Get the full subbuffer size including padding */
1295         err = kernctl_get_padded_subbuf_size(infd, &len);
1296         if (err != 0) {
1297                 PERROR("Getting sub-buffer len failed.");
1298                 err = kernctl_put_subbuf(infd);
1299                 if (err != 0) {
1300                         if (errno == EFAULT) {
1301                                 PERROR("Error in unreserving sub buffer\n");
1302                         } else if (errno == EIO) {
1303                                 /* Should never happen with newer LTTng versions */
1304                                 PERROR("Reader has been pushed by the writer, last sub-buffer corrupted.");
1305                         }
1306                         ret = -errno;
1307                         goto end;
1308                 }
1309                 ret = -errno;
1310                 goto end;
1311         }
1312
1313         if (!stream->metadata_flag) {
1314                 ret = get_index_values(&index, infd);
1315                 if (ret < 0) {
1316                         err = kernctl_put_subbuf(infd);
1317                         if (err != 0) {
1318                                 if (errno == EFAULT) {
1319                                         PERROR("Error in unreserving sub buffer\n");
1320                                 } else if (errno == EIO) {
1321                                         /* Should never happen with newer LTTng versions */
1322                                         PERROR("Reader has been pushed by the writer, last sub-buffer corrupted.");
1323                                 }
1324                                 ret = -errno;
1325                                 goto end;
1326                         }
1327                         goto end;
1328                 }
1329                 ret = update_stream_stats(stream);
1330                 if (ret < 0) {
1331                         err = kernctl_put_subbuf(infd);
1332                         if (err != 0) {
1333                                 if (err == -EFAULT) {
1334                                         PERROR("Error in unreserving sub buffer\n");
1335                                 } else if (err == -EIO) {
1336                                         /* Should never happen with newer LTTng versions */
1337                                         PERROR("Reader has been pushed by the writer, last sub-buffer corrupted.");
1338                                 }
1339                                 ret = err;
1340                                 goto end;
1341                         }
1342                         goto end;
1343                 }
1344         } else {
1345                 write_index = 0;
1346                 ret = metadata_stream_check_version(infd, stream);
1347                 if (ret < 0) {
1348                         err = kernctl_put_subbuf(infd);
1349                         if (err != 0) {
1350                                 if (err == -EFAULT) {
1351                                         PERROR("Error in unreserving sub buffer\n");
1352                                 } else if (err == -EIO) {
1353                                         /* Should never happen with newer LTTng versions */
1354                                         PERROR("Reader has been pushed by the writer, last sub-buffer corrupted.");
1355                                 }
1356                                 ret = err;
1357                                 goto end;
1358                         }
1359                         goto end;
1360                 }
1361         }
1362
1363         switch (stream->chan->output) {
1364         case CONSUMER_CHANNEL_SPLICE:
1365                 /*
1366                  * XXX: The lttng-modules splice "actor" does not handle copying
1367                  * partial pages hence only using the subbuffer size without the
1368                  * padding makes the splice fail.
1369                  */
1370                 subbuf_size = len;
1371                 padding = 0;
1372
1373                 /* splice the subbuffer to the tracefile */
1374                 ret = lttng_consumer_on_read_subbuffer_splice(ctx, stream, subbuf_size,
1375                                 padding, &index);
1376                 /*
1377                  * XXX: Splice does not support network streaming so the return value
1378                  * is simply checked against subbuf_size and not like the mmap() op.
1379                  */
1380                 if (ret != subbuf_size) {
1381                         /*
1382                          * display the error but continue processing to try
1383                          * to release the subbuffer
1384                          */
1385                         ERR("Error splicing to tracefile (ret: %zd != len: %lu)",
1386                                         ret, subbuf_size);
1387                         write_index = 0;
1388                 }
1389                 break;
1390         case CONSUMER_CHANNEL_MMAP:
1391                 /* Get subbuffer size without padding */
1392                 err = kernctl_get_subbuf_size(infd, &subbuf_size);
1393                 if (err != 0) {
1394                         PERROR("Getting sub-buffer len failed.");
1395                         err = kernctl_put_subbuf(infd);
1396                         if (err != 0) {
1397                                 if (errno == EFAULT) {
1398                                         PERROR("Error in unreserving sub buffer\n");
1399                                 } else if (errno == EIO) {
1400                                         /* Should never happen with newer LTTng versions */
1401                                         PERROR("Reader has been pushed by the writer, last sub-buffer corrupted.");
1402                                 }
1403                                 ret = -errno;
1404                                 goto end;
1405                         }
1406                         ret = -errno;
1407                         goto end;
1408                 }
1409
1410                 /* Make sure the tracer is not gone mad on us! */
1411                 assert(len >= subbuf_size);
1412
1413                 padding = len - subbuf_size;
1414
1415                 /* write the subbuffer to the tracefile */
1416                 ret = lttng_consumer_on_read_subbuffer_mmap(ctx, stream, subbuf_size,
1417                                 padding, &index);
1418                 /*
1419                  * The mmap operation should write subbuf_size amount of data when
1420                  * network streaming or the full padding (len) size when we are _not_
1421                  * streaming.
1422                  */
1423                 if ((ret != subbuf_size && stream->net_seq_idx != (uint64_t) -1ULL) ||
1424                                 (ret != len && stream->net_seq_idx == (uint64_t) -1ULL)) {
1425                         /*
1426                          * Display the error but continue processing to try to release the
1427                          * subbuffer. This is a DBG statement since this is possible to
1428                          * happen without being a critical error.
1429                          */
1430                         DBG("Error writing to tracefile "
1431                                         "(ret: %zd != len: %lu != subbuf_size: %lu)",
1432                                         ret, len, subbuf_size);
1433                         write_index = 0;
1434                 }
1435                 break;
1436         default:
1437                 ERR("Unknown output method");
1438                 ret = -EPERM;
1439         }
1440
1441         err = kernctl_put_next_subbuf(infd);
1442         if (err != 0) {
1443                 if (errno == EFAULT) {
1444                         PERROR("Error in unreserving sub buffer\n");
1445                 } else if (errno == EIO) {
1446                         /* Should never happen with newer LTTng versions */
1447                         PERROR("Reader has been pushed by the writer, last sub-buffer corrupted.");
1448                 }
1449                 ret = -errno;
1450                 goto end;
1451         }
1452
1453         /* Write index if needed. */
1454         if (!write_index) {
1455                 goto end;
1456         }
1457
1458         if (stream->chan->live_timer_interval && !stream->metadata_flag) {
1459                 /*
1460                  * In live, block until all the metadata is sent.
1461                  */
1462                 pthread_mutex_lock(&stream->metadata_timer_lock);
1463                 assert(!stream->missed_metadata_flush);
1464                 stream->waiting_on_metadata = true;
1465                 pthread_mutex_unlock(&stream->metadata_timer_lock);
1466
1467                 err = consumer_stream_sync_metadata(ctx, stream->session_id);
1468
1469                 pthread_mutex_lock(&stream->metadata_timer_lock);
1470                 stream->waiting_on_metadata = false;
1471                 if (stream->missed_metadata_flush) {
1472                         stream->missed_metadata_flush = false;
1473                         pthread_mutex_unlock(&stream->metadata_timer_lock);
1474                         (void) consumer_flush_kernel_index(stream);
1475                 } else {
1476                         pthread_mutex_unlock(&stream->metadata_timer_lock);
1477                 }
1478                 if (err < 0) {
1479                         goto end;
1480                 }
1481         }
1482
1483         err = consumer_stream_write_index(stream, &index);
1484         if (err < 0) {
1485                 goto end;
1486         }
1487
1488 end:
1489         return ret;
1490 }
1491
1492 int lttng_kconsumer_on_recv_stream(struct lttng_consumer_stream *stream)
1493 {
1494         int ret;
1495
1496         assert(stream);
1497
1498         /*
1499          * Don't create anything if this is set for streaming or should not be
1500          * monitored.
1501          */
1502         if (stream->net_seq_idx == (uint64_t) -1ULL && stream->chan->monitor) {
1503                 ret = utils_create_stream_file(stream->chan->pathname, stream->name,
1504                                 stream->chan->tracefile_size, stream->tracefile_count_current,
1505                                 stream->uid, stream->gid, NULL);
1506                 if (ret < 0) {
1507                         goto error;
1508                 }
1509                 stream->out_fd = ret;
1510                 stream->tracefile_size_current = 0;
1511
1512                 if (!stream->metadata_flag) {
1513                         struct lttng_index_file *index_file;
1514
1515                         index_file = lttng_index_file_create(stream->chan->pathname,
1516                                         stream->name, stream->uid, stream->gid,
1517                                         stream->chan->tracefile_size,
1518                                         stream->tracefile_count_current,
1519                                         CTF_INDEX_MAJOR, CTF_INDEX_MINOR);
1520                         if (!index_file) {
1521                                 goto error;
1522                         }
1523                         stream->index_file = index_file;
1524                 }
1525         }
1526
1527         if (stream->output == LTTNG_EVENT_MMAP) {
1528                 /* get the len of the mmap region */
1529                 unsigned long mmap_len;
1530
1531                 ret = kernctl_get_mmap_len(stream->wait_fd, &mmap_len);
1532                 if (ret != 0) {
1533                         PERROR("kernctl_get_mmap_len");
1534                         ret = -errno;
1535                         goto error_close_fd;
1536                 }
1537                 stream->mmap_len = (size_t) mmap_len;
1538
1539                 stream->mmap_base = mmap(NULL, stream->mmap_len, PROT_READ,
1540                                 MAP_PRIVATE, stream->wait_fd, 0);
1541                 if (stream->mmap_base == MAP_FAILED) {
1542                         PERROR("Error mmaping");
1543                         ret = -1;
1544                         goto error_close_fd;
1545                 }
1546         }
1547
1548         /* we return 0 to let the library handle the FD internally */
1549         return 0;
1550
1551 error_close_fd:
1552         if (stream->out_fd >= 0) {
1553                 int err;
1554
1555                 err = close(stream->out_fd);
1556                 assert(!err);
1557                 stream->out_fd = -1;
1558         }
1559 error:
1560         return ret;
1561 }
1562
1563 /*
1564  * Check if data is still being extracted from the buffers for a specific
1565  * stream. Consumer data lock MUST be acquired before calling this function
1566  * and the stream lock.
1567  *
1568  * Return 1 if the traced data are still getting read else 0 meaning that the
1569  * data is available for trace viewer reading.
1570  */
1571 int lttng_kconsumer_data_pending(struct lttng_consumer_stream *stream)
1572 {
1573         int ret;
1574
1575         assert(stream);
1576
1577         if (stream->endpoint_status != CONSUMER_ENDPOINT_ACTIVE) {
1578                 ret = 0;
1579                 goto end;
1580         }
1581
1582         ret = kernctl_get_next_subbuf(stream->wait_fd);
1583         if (ret == 0) {
1584                 /* There is still data so let's put back this subbuffer. */
1585                 ret = kernctl_put_subbuf(stream->wait_fd);
1586                 assert(ret == 0);
1587                 ret = 1;   /* Data is pending */
1588                 goto end;
1589         }
1590
1591         /* Data is NOT pending and ready to be read. */
1592         ret = 0;
1593
1594 end:
1595         return ret;
1596 }