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         }
  66
  67         return ret;
  68 }
  69
  70 /*
  71  * Get the produced position
  72  *
  73  * Returns 0 on success, < 0 on error
  74  */
  75 int lttng_kconsumer_get_produced_snapshot(struct lttng_consumer_stream *stream,
  76                 unsigned long *pos)
  77 {
  78         int ret;
  79         int infd = stream->wait_fd;
  80
  81         ret = kernctl_snapshot_get_produced(infd, pos);
  82         if (ret != 0) {
  83                 PERROR("kernctl_snapshot_get_produced");
  84         }
  85
  86         return ret;
  87 }
  88
  89 /*
  90  * Get the consumerd position
  91  *
  92  * Returns 0 on success, < 0 on error
  93  */
  94 int lttng_kconsumer_get_consumed_snapshot(struct lttng_consumer_stream *stream,
  95                 unsigned long *pos)
  96 {
  97         int ret;
  98         int infd = stream->wait_fd;
  99
 100         ret = kernctl_snapshot_get_consumed(infd, pos);
 101         if (ret != 0) {
 102                 PERROR("kernctl_snapshot_get_consumed");
 103         }
 104
 105         return ret;
 106 }
 107
 108 /*
 109  * Take a snapshot of all the stream of a channel
 110  *
 111  * Returns 0 on success, < 0 on error
 112  */
 113 int lttng_kconsumer_snapshot_channel(uint64_t key, char *path,
 114                 uint64_t relayd_id, uint64_t nb_packets_per_stream,
 115                 struct lttng_consumer_local_data *ctx)
 116 {
 117         int ret;
 118         struct lttng_consumer_channel *channel;
 119         struct lttng_consumer_stream *stream;
 120
 121         DBG("Kernel consumer snapshot channel %" PRIu64, key);
 122
 123         rcu_read_lock();
 124
 125         channel = consumer_find_channel(key);
 126         if (!channel) {
 127                 ERR("No channel found for key %" PRIu64, key);
 128                 ret = -1;
 129                 goto end;
 130         }
 131
 132         /* Splice is not supported yet for channel snapshot. */
 133         if (channel->output != CONSUMER_CHANNEL_MMAP) {
 134                 ERR("Unsupported output %d", channel->output);
 135                 ret = -1;
 136                 goto end;
 137         }
 138
 139         cds_list_for_each_entry(stream, &channel->streams.head, send_node) {
 140                 /* Are we at a position _before_ the first available packet ? */
 141                 bool before_first_packet = true;
 142                 unsigned long consumed_pos, produced_pos;
 143
 144                 health_code_update();
 145
 146                 /*
 147                  * Lock stream because we are about to change its state.
 148                  */
 149                 pthread_mutex_lock(&stream->lock);
 150
 151                 /*
 152                  * Assign the received relayd ID so we can use it for streaming. The streams
 153                  * are not visible to anyone so this is OK to change it.
 154                  */
 155                 stream->net_seq_idx = relayd_id;
 156                 channel->relayd_id = relayd_id;
 157                 if (relayd_id != (uint64_t) -1ULL) {
 158                         ret = consumer_send_relayd_stream(stream, path);
 159                         if (ret < 0) {
 160                                 ERR("sending stream to relayd");
 161                                 goto end_unlock;
 162                         }
 163                 } else {
 164                         ret = utils_create_stream_file(path, stream->name,
 165                                         stream->chan->tracefile_size,
 166                                         stream->tracefile_count_current,
 167                                         stream->uid, stream->gid, NULL);
 168                         if (ret < 0) {
 169                                 ERR("utils_create_stream_file");
 170                                 goto end_unlock;
 171                         }
 172
 173                         stream->out_fd = ret;
 174                         stream->tracefile_size_current = 0;
 175
 176                         DBG("Kernel consumer snapshot stream %s/%s (%" PRIu64 ")",
 177                                         path, stream->name, stream->key);
 178                 }
 179                 if (relayd_id != -1ULL) {
 180                         ret = consumer_send_relayd_streams_sent(relayd_id);
 181                         if (ret < 0) {
 182                                 ERR("sending streams sent to relayd");
 183                                 goto end_unlock;
 184                         }
 185                         channel->streams_sent_to_relayd = true;
 186                 }
 187
 188                 ret = kernctl_buffer_flush_empty(stream->wait_fd);
 189                 if (ret < 0) {
 190                         /*
 191                          * Doing a buffer flush which does not take into
 192                          * account empty packets. This is not perfect
 193                          * for stream intersection, but required as a
 194                          * fall-back when "flush_empty" is not
 195                          * implemented by lttng-modules.
 196                          */
 197                         ret = kernctl_buffer_flush(stream->wait_fd);
 198                         if (ret < 0) {
 199                                 ERR("Failed to flush kernel stream");
 200                                 goto end_unlock;
 201                         }
 202                         goto end_unlock;
 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                                 goto end_unlock;
 229                         }
 230                 }
 231
 232                 consumed_pos = consumer_get_consume_start_pos(consumed_pos,
 233                                 produced_pos, nb_packets_per_stream,
 234                                 stream->max_sb_size);
 235
 236                 while (consumed_pos < produced_pos) {
 237                         ssize_t read_len;
 238                         unsigned long len, padded_len;
 239                         int lost_packet = 0;
 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 (ret != -EAGAIN) {
 248                                         PERROR("kernctl_get_subbuf snapshot");
 249                                         goto end_unlock;
 250                                 }
 251                                 DBG("Kernel consumer get subbuf failed. Skipping it.");
 252                                 consumed_pos += stream->max_sb_size;
 253
 254                                 /*
 255                                  * Start accounting lost packets only when we
 256                                  * already have extracted packets (to match the
 257                                  * content of the final snapshot).
 258                                  */
 259                                 if (!before_first_packet) {
 260                                         lost_packet = 1;
 261                                 }
 262                                 continue;
 263                         }
 264
 265                         ret = kernctl_get_subbuf_size(stream->wait_fd, &len);
 266                         if (ret < 0) {
 267                                 ERR("Snapshot kernctl_get_subbuf_size");
 268                                 goto error_put_subbuf;
 269                         }
 270
 271                         ret = kernctl_get_padded_subbuf_size(stream->wait_fd, &padded_len);
 272                         if (ret < 0) {
 273                                 ERR("Snapshot kernctl_get_padded_subbuf_size");
 274                                 goto error_put_subbuf;
 275                         }
 276
 277                         read_len = lttng_consumer_on_read_subbuffer_mmap(ctx, stream, len,
 278                                         padded_len - len, NULL);
 279                         /*
 280                          * We write the padded len in local tracefiles but the data len
 281                          * when using a relay. Display the error but continue processing
 282                          * to try to release the subbuffer.
 283                          */
 284                         if (relayd_id != (uint64_t) -1ULL) {
 285                                 if (read_len != len) {
 286                                         ERR("Error sending to the relay (ret: %zd != len: %lu)",
 287                                                         read_len, len);
 288                                 }
 289                         } else {
 290                                 if (read_len != padded_len) {
 291                                         ERR("Error writing to tracefile (ret: %zd != len: %lu)",
 292                                                         read_len, padded_len);
 293                                 }
 294                         }
 295
 296                         ret = kernctl_put_subbuf(stream->wait_fd);
 297                         if (ret < 0) {
 298                                 ERR("Snapshot kernctl_put_subbuf");
 299                                 goto end_unlock;
 300                         }
 301                         consumed_pos += stream->max_sb_size;
 302
 303                         /*
 304                          * Only account lost packets located between
 305                          * succesfully extracted packets (do not account before
 306                          * and after since they are not visible in the
 307                          * resulting snapshot).
 308                          */
 309                         stream->chan->lost_packets += lost_packet;
 310                         lost_packet = 0;
 311                         before_first_packet = false;
 312                 }
 313
 314                 if (relayd_id == (uint64_t) -1ULL) {
 315                         if (stream->out_fd >= 0) {
 316                                 ret = close(stream->out_fd);
 317                                 if (ret < 0) {
 318                                         PERROR("Kernel consumer snapshot close out_fd");
 319                                         goto end_unlock;
 320                                 }
 321                                 stream->out_fd = -1;
 322                         }
 323                 } else {
 324                         close_relayd_stream(stream);
 325                         stream->net_seq_idx = (uint64_t) -1ULL;
 326                 }
 327                 pthread_mutex_unlock(&stream->lock);
 328         }
 329
 330         /* All good! */
 331         ret = 0;
 332         goto end;
 333
 334 error_put_subbuf:
 335         ret = kernctl_put_subbuf(stream->wait_fd);
 336         if (ret < 0) {
 337                 ERR("Snapshot kernctl_put_subbuf error path");
 338         }
 339 end_unlock:
 340         pthread_mutex_unlock(&stream->lock);
 341 end:
 342         rcu_read_unlock();
 343         return ret;
 344 }
 345
 346 /*
 347  * Read the whole metadata available for a snapshot.
 348  *
 349  * Returns 0 on success, < 0 on error
 350  */
 351 int lttng_kconsumer_snapshot_metadata(uint64_t key, char *path,
 352                 uint64_t relayd_id, struct lttng_consumer_local_data *ctx)
 353 {
 354         int ret, use_relayd = 0;
 355         ssize_t ret_read;
 356         struct lttng_consumer_channel *metadata_channel;
 357         struct lttng_consumer_stream *metadata_stream;
 358
 359         assert(ctx);
 360
 361         DBG("Kernel consumer snapshot metadata with key %" PRIu64 " at path %s",
 362                         key, path);
 363
 364         rcu_read_lock();
 365
 366         metadata_channel = consumer_find_channel(key);
 367         if (!metadata_channel) {
 368                 ERR("Kernel snapshot metadata not found for key %" PRIu64, key);
 369                 ret = -1;
 370                 goto error;
 371         }
 372
 373         metadata_stream = metadata_channel->metadata_stream;
 374         assert(metadata_stream);
 375
 376         /* Flag once that we have a valid relayd for the stream. */
 377         if (relayd_id != (uint64_t) -1ULL) {
 378                 use_relayd = 1;
 379         }
 380
 381         if (use_relayd) {
 382                 ret = consumer_send_relayd_stream(metadata_stream, path);
 383                 if (ret < 0) {
 384                         goto error;
 385                 }
 386         } else {
 387                 ret = utils_create_stream_file(path, metadata_stream->name,
 388                                 metadata_stream->chan->tracefile_size,
 389                                 metadata_stream->tracefile_count_current,
 390                                 metadata_stream->uid, metadata_stream->gid, NULL);
 391                 if (ret < 0) {
 392                         goto error;
 393                 }
 394                 metadata_stream->out_fd = ret;
 395         }
 396
 397         do {
 398                 health_code_update();
 399
 400                 ret_read = lttng_kconsumer_read_subbuffer(metadata_stream, ctx);
 401                 if (ret_read < 0) {
 402                         if (ret_read != -EAGAIN) {
 403                                 ERR("Kernel snapshot reading metadata subbuffer (ret: %zd)",
 404                                                 ret_read);
 405                                 goto error;
 406                         }
 407                         /* ret_read is negative at this point so we will exit the loop. */
 408                         continue;
 409                 }
 410         } while (ret_read >= 0);
 411
 412         if (use_relayd) {
 413                 close_relayd_stream(metadata_stream);
 414                 metadata_stream->net_seq_idx = (uint64_t) -1ULL;
 415         } else {
 416                 if (metadata_stream->out_fd >= 0) {
 417                         ret = close(metadata_stream->out_fd);
 418                         if (ret < 0) {
 419                                 PERROR("Kernel consumer snapshot metadata close out_fd");
 420                                 /*
 421                                  * Don't go on error here since the snapshot was successful at this
 422                                  * point but somehow the close failed.
 423                                  */
 424                         }
 425                         metadata_stream->out_fd = -1;
 426                 }
 427         }
 428
 429         ret = 0;
 430
 431         cds_list_del(&metadata_stream->send_node);
 432         consumer_stream_destroy(metadata_stream, NULL);
 433         metadata_channel->metadata_stream = NULL;
 434 error:
 435         rcu_read_unlock();
 436         return ret;
 437 }
 438
 439 /*
 440  * Receive command from session daemon and process it.
 441  *
 442  * Return 1 on success else a negative value or 0.
 443  */
 444 int lttng_kconsumer_recv_cmd(struct lttng_consumer_local_data *ctx,
 445                 int sock, struct pollfd *consumer_sockpoll)
 446 {
 447         ssize_t ret;
 448         enum lttcomm_return_code ret_code = LTTCOMM_CONSUMERD_SUCCESS;
 449         struct lttcomm_consumer_msg msg;
 450
 451         health_code_update();
 452
 453         ret = lttcomm_recv_unix_sock(sock, &msg, sizeof(msg));
 454         if (ret != sizeof(msg)) {
 455                 if (ret > 0) {
 456                         lttng_consumer_send_error(ctx, LTTCOMM_CONSUMERD_ERROR_RECV_CMD);
 457                         ret = -1;
 458                 }
 459                 return ret;
 460         }
 461
 462         health_code_update();
 463
 464         /* Deprecated command */
 465         assert(msg.cmd_type != LTTNG_CONSUMER_STOP);
 466
 467         health_code_update();
 468
 469         /* relayd needs RCU read-side protection */
 470         rcu_read_lock();
 471
 472         switch (msg.cmd_type) {
 473         case LTTNG_CONSUMER_ADD_RELAYD_SOCKET:
 474         {
 475                 /* Session daemon status message are handled in the following call. */
 476                 ret = consumer_add_relayd_socket(msg.u.relayd_sock.net_index,
 477                                 msg.u.relayd_sock.type, ctx, sock, consumer_sockpoll,
 478                                 &msg.u.relayd_sock.sock, msg.u.relayd_sock.session_id,
 479                                  msg.u.relayd_sock.relayd_session_id);
 480                 goto end_nosignal;
 481         }
 482         case LTTNG_CONSUMER_ADD_CHANNEL:
 483         {
 484                 struct lttng_consumer_channel *new_channel;
 485                 int ret_recv;
 486
 487                 health_code_update();
 488
 489                 /* First send a status message before receiving the fds. */
 490                 ret = consumer_send_status_msg(sock, ret_code);
 491                 if (ret < 0) {
 492                         /* Somehow, the session daemon is not responding anymore. */
 493                         goto error_fatal;
 494                 }
 495
 496                 health_code_update();
 497
 498                 DBG("consumer_add_channel %" PRIu64, msg.u.channel.channel_key);
 499                 new_channel = consumer_allocate_channel(msg.u.channel.channel_key,
 500                                 msg.u.channel.session_id, msg.u.channel.pathname,
 501                                 msg.u.channel.name, msg.u.channel.uid, msg.u.channel.gid,
 502                                 msg.u.channel.relayd_id, msg.u.channel.output,
 503                                 msg.u.channel.tracefile_size,
 504                                 msg.u.channel.tracefile_count, 0,
 505                                 msg.u.channel.monitor,
 506                                 msg.u.channel.live_timer_interval,
 507                                 NULL, NULL);
 508                 if (new_channel == NULL) {
 509                         lttng_consumer_send_error(ctx, LTTCOMM_CONSUMERD_OUTFD_ERROR);
 510                         goto end_nosignal;
 511                 }
 512                 new_channel->nb_init_stream_left = msg.u.channel.nb_init_streams;
 513                 switch (msg.u.channel.output) {
 514                 case LTTNG_EVENT_SPLICE:
 515                         new_channel->output = CONSUMER_CHANNEL_SPLICE;
 516                         break;
 517                 case LTTNG_EVENT_MMAP:
 518                         new_channel->output = CONSUMER_CHANNEL_MMAP;
 519                         break;
 520                 default:
 521                         ERR("Channel output unknown %d", msg.u.channel.output);
 522                         goto end_nosignal;
 523                 }
 524
 525                 /* Translate and save channel type. */
 526                 switch (msg.u.channel.type) {
 527                 case CONSUMER_CHANNEL_TYPE_DATA:
 528                 case CONSUMER_CHANNEL_TYPE_METADATA:
 529                         new_channel->type = msg.u.channel.type;
 530                         break;
 531                 default:
 532                         assert(0);
 533                         goto end_nosignal;
 534                 };
 535
 536                 health_code_update();
 537
 538                 if (ctx->on_recv_channel != NULL) {
 539                         ret_recv = ctx->on_recv_channel(new_channel);
 540                         if (ret_recv == 0) {
 541                                 ret = consumer_add_channel(new_channel, ctx);
 542                         } else if (ret_recv < 0) {
 543                                 goto end_nosignal;
 544                         }
 545                 } else {
 546                         ret = consumer_add_channel(new_channel, ctx);
 547                 }
 548                 if (CONSUMER_CHANNEL_TYPE_DATA) {
 549                         consumer_timer_live_start(new_channel,
 550                                         msg.u.channel.live_timer_interval);
 551                 }
 552
 553                 health_code_update();
 554
 555                 /* If we received an error in add_channel, we need to report it. */
 556                 if (ret < 0) {
 557                         ret = consumer_send_status_msg(sock, ret);
 558                         if (ret < 0) {
 559                                 goto error_fatal;
 560                         }
 561                         goto end_nosignal;
 562                 }
 563
 564                 goto end_nosignal;
 565         }
 566         case LTTNG_CONSUMER_ADD_STREAM:
 567         {
 568                 int fd;
 569                 struct lttng_pipe *stream_pipe;
 570                 struct lttng_consumer_stream *new_stream;
 571                 struct lttng_consumer_channel *channel;
 572                 int alloc_ret = 0;
 573
 574                 /*
 575                  * Get stream's channel reference. Needed when adding the stream to the
 576                  * global hash table.
 577                  */
 578                 channel = consumer_find_channel(msg.u.stream.channel_key);
 579                 if (!channel) {
 580                         /*
 581                          * We could not find the channel. Can happen if cpu hotplug
 582                          * happens while tearing down.
 583                          */
 584                         ERR("Unable to find channel key %" PRIu64, msg.u.stream.channel_key);
 585                         ret_code = LTTCOMM_CONSUMERD_CHAN_NOT_FOUND;
 586                 }
 587
 588                 health_code_update();
 589
 590                 /* First send a status message before receiving the fds. */
 591                 ret = consumer_send_status_msg(sock, ret_code);
 592                 if (ret < 0) {
 593                         /* Somehow, the session daemon is not responding anymore. */
 594                         goto error_fatal;
 595                 }
 596
 597                 health_code_update();
 598
 599                 if (ret_code != LTTCOMM_CONSUMERD_SUCCESS) {
 600                         /* Channel was not found. */
 601                         goto end_nosignal;
 602                 }
 603
 604                 /* Blocking call */
 605                 health_poll_entry();
 606                 ret = lttng_consumer_poll_socket(consumer_sockpoll);
 607                 health_poll_exit();
 608                 if (ret) {
 609                         goto error_fatal;
 610                 }
 611
 612                 health_code_update();
 613
 614                 /* Get stream file descriptor from socket */
 615                 ret = lttcomm_recv_fds_unix_sock(sock, &fd, 1);
 616                 if (ret != sizeof(fd)) {
 617                         lttng_consumer_send_error(ctx, LTTCOMM_CONSUMERD_ERROR_RECV_FD);
 618                         rcu_read_unlock();
 619                         return ret;
 620                 }
 621
 622                 health_code_update();
 623
 624                 /*
 625                  * Send status code to session daemon only if the recv works. If the
 626                  * above recv() failed, the session daemon is notified through the
 627                  * error socket and the teardown is eventually done.
 628                  */
 629                 ret = consumer_send_status_msg(sock, ret_code);
 630                 if (ret < 0) {
 631                         /* Somehow, the session daemon is not responding anymore. */
 632                         goto end_nosignal;
 633                 }
 634
 635                 health_code_update();
 636
 637                 new_stream = consumer_allocate_stream(channel->key,
 638                                 fd,
 639                                 LTTNG_CONSUMER_ACTIVE_STREAM,
 640                                 channel->name,
 641                                 channel->uid,
 642                                 channel->gid,
 643                                 channel->relayd_id,
 644                                 channel->session_id,
 645                                 msg.u.stream.cpu,
 646                                 &alloc_ret,
 647                                 channel->type,
 648                                 channel->monitor);
 649                 if (new_stream == NULL) {
 650                         switch (alloc_ret) {
 651                         case -ENOMEM:
 652                         case -EINVAL:
 653                         default:
 654                                 lttng_consumer_send_error(ctx, LTTCOMM_CONSUMERD_OUTFD_ERROR);
 655                                 break;
 656                         }
 657                         goto end_nosignal;
 658                 }
 659
 660                 new_stream->chan = channel;
 661                 new_stream->wait_fd = fd;
 662                 switch (channel->output) {
 663                 case CONSUMER_CHANNEL_SPLICE:
 664                         new_stream->output = LTTNG_EVENT_SPLICE;
 665                         ret = utils_create_pipe(new_stream->splice_pipe);
 666                         if (ret < 0) {
 667                                 goto end_nosignal;
 668                         }
 669                         break;
 670                 case CONSUMER_CHANNEL_MMAP:
 671                         new_stream->output = LTTNG_EVENT_MMAP;
 672                         break;
 673                 default:
 674                         ERR("Stream output unknown %d", channel->output);
 675                         goto end_nosignal;
 676                 }
 677
 678                 /*
 679                  * We've just assigned the channel to the stream so increment the
 680                  * refcount right now. We don't need to increment the refcount for
 681                  * streams in no monitor because we handle manually the cleanup of
 682                  * those. It is very important to make sure there is NO prior
 683                  * consumer_del_stream() calls or else the refcount will be unbalanced.
 684                  */
 685                 if (channel->monitor) {
 686                         uatomic_inc(&new_stream->chan->refcount);
 687                 }
 688
 689                 /*
 690                  * The buffer flush is done on the session daemon side for the kernel
 691                  * so no need for the stream "hangup_flush_done" variable to be
 692                  * tracked. This is important for a kernel stream since we don't rely
 693                  * on the flush state of the stream to read data. It's not the case for
 694                  * user space tracing.
 695                  */
 696                 new_stream->hangup_flush_done = 0;
 697
 698                 health_code_update();
 699
 700                 if (ctx->on_recv_stream) {
 701                         ret = ctx->on_recv_stream(new_stream);
 702                         if (ret < 0) {
 703                                 consumer_stream_free(new_stream);
 704                                 goto end_nosignal;
 705                         }
 706                 }
 707
 708                 health_code_update();
 709
 710                 if (new_stream->metadata_flag) {
 711                         channel->metadata_stream = new_stream;
 712                 }
 713
 714                 /* Do not monitor this stream. */
 715                 if (!channel->monitor) {
 716                         DBG("Kernel consumer add stream %s in no monitor mode with "
 717                                         "relayd id %" PRIu64, new_stream->name,
 718                                         new_stream->net_seq_idx);
 719                         cds_list_add(&new_stream->send_node, &channel->streams.head);
 720                         break;
 721                 }
 722
 723                 /* Send stream to relayd if the stream has an ID. */
 724                 if (new_stream->net_seq_idx != (uint64_t) -1ULL) {
 725                         ret = consumer_send_relayd_stream(new_stream,
 726                                         new_stream->chan->pathname);
 727                         if (ret < 0) {
 728                                 consumer_stream_free(new_stream);
 729                                 goto end_nosignal;
 730                         }
 731
 732                         /*
 733                          * If adding an extra stream to an already
 734                          * existing channel (e.g. cpu hotplug), we need
 735                          * to send the "streams_sent" command to relayd.
 736                          */
 737                         if (channel->streams_sent_to_relayd) {
 738                                 ret = consumer_send_relayd_streams_sent(
 739                                                 new_stream->net_seq_idx);
 740                                 if (ret < 0) {
 741                                         goto end_nosignal;
 742                                 }
 743                         }
 744                 }
 745
 746                 /* Get the right pipe where the stream will be sent. */
 747                 if (new_stream->metadata_flag) {
 748                         ret = consumer_add_metadata_stream(new_stream);
 749                         if (ret) {
 750                                 ERR("Consumer add metadata stream %" PRIu64 " failed. Continuing",
 751                                                 new_stream->key);
 752                                 consumer_stream_free(new_stream);
 753                                 goto end_nosignal;
 754                         }
 755                         stream_pipe = ctx->consumer_metadata_pipe;
 756                 } else {
 757                         ret = consumer_add_data_stream(new_stream);
 758                         if (ret) {
 759                                 ERR("Consumer add stream %" PRIu64 " failed. Continuing",
 760                                                 new_stream->key);
 761                                 consumer_stream_free(new_stream);
 762                                 goto end_nosignal;
 763                         }
 764                         stream_pipe = ctx->consumer_data_pipe;
 765                 }
 766
 767                 /* Vitible to other threads */
 768                 new_stream->globally_visible = 1;
 769
 770                 health_code_update();
 771
 772                 ret = lttng_pipe_write(stream_pipe, &new_stream, sizeof(new_stream));
 773                 if (ret < 0) {
 774                         ERR("Consumer write %s stream to pipe %d",
 775                                         new_stream->metadata_flag ? "metadata" : "data",
 776                                         lttng_pipe_get_writefd(stream_pipe));
 777                         if (new_stream->metadata_flag) {
 778                                 consumer_del_stream_for_metadata(new_stream);
 779                         } else {
 780                                 consumer_del_stream_for_data(new_stream);
 781                         }
 782                         goto end_nosignal;
 783                 }
 784
 785                 DBG("Kernel consumer ADD_STREAM %s (fd: %d) with relayd id %" PRIu64,
 786                                 new_stream->name, fd, new_stream->relayd_stream_id);
 787                 break;
 788         }
 789         case LTTNG_CONSUMER_STREAMS_SENT:
 790         {
 791                 struct lttng_consumer_channel *channel;
 792
 793                 /*
 794                  * Get stream's channel reference. Needed when adding the stream to the
 795                  * global hash table.
 796                  */
 797                 channel = consumer_find_channel(msg.u.sent_streams.channel_key);
 798                 if (!channel) {
 799                         /*
 800                          * We could not find the channel. Can happen if cpu hotplug
 801                          * happens while tearing down.
 802                          */
 803                         ERR("Unable to find channel key %" PRIu64,
 804                                         msg.u.sent_streams.channel_key);
 805                         ret_code = LTTCOMM_CONSUMERD_CHAN_NOT_FOUND;
 806                 }
 807
 808                 health_code_update();
 809
 810                 /*
 811                  * Send status code to session daemon.
 812                  */
 813                 ret = consumer_send_status_msg(sock, ret_code);
 814                 if (ret < 0 || ret_code != LTTCOMM_CONSUMERD_SUCCESS) {
 815                         /* Somehow, the session daemon is not responding anymore. */
 816                         goto end_nosignal;
 817                 }
 818
 819                 health_code_update();
 820
 821                 /*
 822                  * We should not send this message if we don't monitor the
 823                  * streams in this channel.
 824                  */
 825                 if (!channel->monitor) {
 826                         break;
 827                 }
 828
 829                 health_code_update();
 830                 /* Send stream to relayd if the stream has an ID. */
 831                 if (msg.u.sent_streams.net_seq_idx != (uint64_t) -1ULL) {
 832                         ret = consumer_send_relayd_streams_sent(
 833                                         msg.u.sent_streams.net_seq_idx);
 834                         if (ret < 0) {
 835                                 goto end_nosignal;
 836                         }
 837                         channel->streams_sent_to_relayd = true;
 838                 }
 839                 break;
 840         }
 841         case LTTNG_CONSUMER_UPDATE_STREAM:
 842         {
 843                 rcu_read_unlock();
 844                 return -ENOSYS;
 845         }
 846         case LTTNG_CONSUMER_DESTROY_RELAYD:
 847         {
 848                 uint64_t index = msg.u.destroy_relayd.net_seq_idx;
 849                 struct consumer_relayd_sock_pair *relayd;
 850
 851                 DBG("Kernel consumer destroying relayd %" PRIu64, index);
 852
 853                 /* Get relayd reference if exists. */
 854                 relayd = consumer_find_relayd(index);
 855                 if (relayd == NULL) {
 856                         DBG("Unable to find relayd %" PRIu64, index);
 857                         ret_code = LTTCOMM_CONSUMERD_RELAYD_FAIL;
 858                 }
 859
 860                 /*
 861                  * Each relayd socket pair has a refcount of stream attached to it
 862                  * which tells if the relayd is still active or not depending on the
 863                  * refcount value.
 864                  *
 865                  * This will set the destroy flag of the relayd object and destroy it
 866                  * if the refcount reaches zero when called.
 867                  *
 868                  * The destroy can happen either here or when a stream fd hangs up.
 869                  */
 870                 if (relayd) {
 871                         consumer_flag_relayd_for_destroy(relayd);
 872                 }
 873
 874                 health_code_update();
 875
 876                 ret = consumer_send_status_msg(sock, ret_code);
 877                 if (ret < 0) {
 878                         /* Somehow, the session daemon is not responding anymore. */
 879                         goto error_fatal;
 880                 }
 881
 882                 goto end_nosignal;
 883         }
 884         case LTTNG_CONSUMER_DATA_PENDING:
 885         {
 886                 int32_t ret;
 887                 uint64_t id = msg.u.data_pending.session_id;
 888
 889                 DBG("Kernel consumer data pending command for id %" PRIu64, id);
 890
 891                 ret = consumer_data_pending(id);
 892
 893                 health_code_update();
 894
 895                 /* Send back returned value to session daemon */
 896                 ret = lttcomm_send_unix_sock(sock, &ret, sizeof(ret));
 897                 if (ret < 0) {
 898                         PERROR("send data pending ret code");
 899                         goto error_fatal;
 900                 }
 901
 902                 /*
 903                  * No need to send back a status message since the data pending
 904                  * returned value is the response.
 905                  */
 906                 break;
 907         }
 908         case LTTNG_CONSUMER_SNAPSHOT_CHANNEL:
 909         {
 910                 if (msg.u.snapshot_channel.metadata == 1) {
 911                         ret = lttng_kconsumer_snapshot_metadata(msg.u.snapshot_channel.key,
 912                                         msg.u.snapshot_channel.pathname,
 913                                         msg.u.snapshot_channel.relayd_id, ctx);
 914                         if (ret < 0) {
 915                                 ERR("Snapshot metadata failed");
 916                                 ret_code = LTTCOMM_CONSUMERD_ERROR_METADATA;
 917                         }
 918                 } else {
 919                         ret = lttng_kconsumer_snapshot_channel(msg.u.snapshot_channel.key,
 920                                         msg.u.snapshot_channel.pathname,
 921                                         msg.u.snapshot_channel.relayd_id,
 922                                         msg.u.snapshot_channel.nb_packets_per_stream,
 923                                         ctx);
 924                         if (ret < 0) {
 925                                 ERR("Snapshot channel failed");
 926                                 ret_code = LTTCOMM_CONSUMERD_CHAN_NOT_FOUND;
 927                         }
 928                 }
 929
 930                 health_code_update();
 931
 932                 ret = consumer_send_status_msg(sock, ret_code);
 933                 if (ret < 0) {
 934                         /* Somehow, the session daemon is not responding anymore. */
 935                         goto end_nosignal;
 936                 }
 937                 break;
 938         }
 939         case LTTNG_CONSUMER_DESTROY_CHANNEL:
 940         {
 941                 uint64_t key = msg.u.destroy_channel.key;
 942                 struct lttng_consumer_channel *channel;
 943
 944                 channel = consumer_find_channel(key);
 945                 if (!channel) {
 946                         ERR("Kernel consumer destroy channel %" PRIu64 " not found", key);
 947                         ret_code = LTTCOMM_CONSUMERD_CHAN_NOT_FOUND;
 948                 }
 949
 950                 health_code_update();
 951
 952                 ret = consumer_send_status_msg(sock, ret_code);
 953                 if (ret < 0) {
 954                         /* Somehow, the session daemon is not responding anymore. */
 955                         goto end_nosignal;
 956                 }
 957
 958                 health_code_update();
 959
 960                 /* Stop right now if no channel was found. */
 961                 if (!channel) {
 962                         goto end_nosignal;
 963                 }
 964
 965                 /*
 966                  * This command should ONLY be issued for channel with streams set in
 967                  * no monitor mode.
 968                  */
 969                 assert(!channel->monitor);
 970
 971                 /*
 972                  * The refcount should ALWAYS be 0 in the case of a channel in no
 973                  * monitor mode.
 974                  */
 975                 assert(!uatomic_sub_return(&channel->refcount, 1));
 976
 977                 consumer_del_channel(channel);
 978
 979                 goto end_nosignal;
 980         }
 981         case LTTNG_CONSUMER_DISCARDED_EVENTS:
 982         {
 983                 uint64_t ret;
 984                 struct lttng_consumer_channel *channel;
 985                 uint64_t id = msg.u.discarded_events.session_id;
 986                 uint64_t key = msg.u.discarded_events.channel_key;
 987
 988                 DBG("Kernel consumer discarded events command for session id %"
 989                                 PRIu64 ", channel key %" PRIu64, id, key);
 990
 991                 channel = consumer_find_channel(key);
 992                 if (!channel) {
 993                         ERR("Kernel consumer discarded events channel %"
 994                                         PRIu64 " not found", key);
 995                         ret = 0;
 996                 } else {
 997                         ret = channel->discarded_events;
 998                 }
 999
1000                 health_code_update();
1001
1002                 /* Send back returned value to session daemon */
1003                 ret = lttcomm_send_unix_sock(sock, &ret, sizeof(ret));
1004                 if (ret < 0) {
1005                         PERROR("send discarded events");
1006                         goto error_fatal;
1007                 }
1008
1009                 break;
1010         }
1011         case LTTNG_CONSUMER_LOST_PACKETS:
1012         {
1013                 uint64_t ret;
1014                 struct lttng_consumer_channel *channel;
1015                 uint64_t id = msg.u.lost_packets.session_id;
1016                 uint64_t key = msg.u.lost_packets.channel_key;
1017
1018                 DBG("Kernel consumer lost packets command for session id %"
1019                                 PRIu64 ", channel key %" PRIu64, id, key);
1020
1021                 channel = consumer_find_channel(key);
1022                 if (!channel) {
1023                         ERR("Kernel consumer lost packets channel %"
1024                                         PRIu64 " not found", key);
1025                         ret = 0;
1026                 } else {
1027                         ret = channel->lost_packets;
1028                 }
1029
1030                 health_code_update();
1031
1032                 /* Send back returned value to session daemon */
1033                 ret = lttcomm_send_unix_sock(sock, &ret, sizeof(ret));
1034                 if (ret < 0) {
1035                         PERROR("send lost packets");
1036                         goto error_fatal;
1037                 }
1038
1039                 break;
1040         }
1041         default:
1042                 goto end_nosignal;
1043         }
1044
1045 end_nosignal:
1046         rcu_read_unlock();
1047
1048         /*
1049          * Return 1 to indicate success since the 0 value can be a socket
1050          * shutdown during the recv() or send() call.
1051          */
1052         health_code_update();
1053         return 1;
1054
1055 error_fatal:
1056         rcu_read_unlock();
1057         /* This will issue a consumer stop. */
1058         return -1;
1059 }
1060
1061 /*
1062  * Populate index values of a kernel stream. Values are set in big endian order.
1063  *
1064  * Return 0 on success or else a negative value.
1065  */
1066 static int get_index_values(struct ctf_packet_index *index, int infd)
1067 {
1068         int ret;
1069
1070         ret = kernctl_get_timestamp_begin(infd, &index->timestamp_begin);
1071         if (ret < 0) {
1072                 PERROR("kernctl_get_timestamp_begin");
1073                 goto error;
1074         }
1075         index->timestamp_begin = htobe64(index->timestamp_begin);
1076
1077         ret = kernctl_get_timestamp_end(infd, &index->timestamp_end);
1078         if (ret < 0) {
1079                 PERROR("kernctl_get_timestamp_end");
1080                 goto error;
1081         }
1082         index->timestamp_end = htobe64(index->timestamp_end);
1083
1084         ret = kernctl_get_events_discarded(infd, &index->events_discarded);
1085         if (ret < 0) {
1086                 PERROR("kernctl_get_events_discarded");
1087                 goto error;
1088         }
1089         index->events_discarded = htobe64(index->events_discarded);
1090
1091         ret = kernctl_get_content_size(infd, &index->content_size);
1092         if (ret < 0) {
1093                 PERROR("kernctl_get_content_size");
1094                 goto error;
1095         }
1096         index->content_size = htobe64(index->content_size);
1097
1098         ret = kernctl_get_packet_size(infd, &index->packet_size);
1099         if (ret < 0) {
1100                 PERROR("kernctl_get_packet_size");
1101                 goto error;
1102         }
1103         index->packet_size = htobe64(index->packet_size);
1104
1105         ret = kernctl_get_stream_id(infd, &index->stream_id);
1106         if (ret < 0) {
1107                 PERROR("kernctl_get_stream_id");
1108                 goto error;
1109         }
1110         index->stream_id = htobe64(index->stream_id);
1111
1112         ret = kernctl_get_instance_id(infd, &index->stream_instance_id);
1113         if (ret < 0) {
1114                 if (ret == -ENOTTY) {
1115                         /* Command not implemented by lttng-modules. */
1116                         index->stream_instance_id = -1ULL;
1117                         ret = 0;
1118                 } else {
1119                         PERROR("kernctl_get_instance_id");
1120                         goto error;
1121                 }
1122         }
1123         index->stream_instance_id = htobe64(index->stream_instance_id);
1124
1125         ret = kernctl_get_sequence_number(infd, &index->packet_seq_num);
1126         if (ret < 0) {
1127                 if (ret == -ENOTTY) {
1128                         /* Command not implemented by lttng-modules. */
1129                         index->packet_seq_num = -1ULL;
1130                         ret = 0;
1131                 } else {
1132                         PERROR("kernctl_get_sequence_number");
1133                         goto error;
1134                 }
1135         }
1136         index->packet_seq_num = htobe64(index->packet_seq_num);
1137
1138 error:
1139         return ret;
1140 }
1141 /*
1142  * Sync metadata meaning request them to the session daemon and snapshot to the
1143  * metadata thread can consumer them.
1144  *
1145  * Metadata stream lock MUST be acquired.
1146  *
1147  * Return 0 if new metadatda is available, EAGAIN if the metadata stream
1148  * is empty or a negative value on error.
1149  */
1150 int lttng_kconsumer_sync_metadata(struct lttng_consumer_stream *metadata)
1151 {
1152         int ret;
1153
1154         assert(metadata);
1155
1156         ret = kernctl_buffer_flush(metadata->wait_fd);
1157         if (ret < 0) {
1158                 ERR("Failed to flush kernel stream");
1159                 goto end;
1160         }
1161
1162         ret = kernctl_snapshot(metadata->wait_fd);
1163         if (ret < 0) {
1164                 if (ret != -EAGAIN) {
1165                         ERR("Sync metadata, taking kernel snapshot failed.");
1166                         goto end;
1167                 }
1168                 DBG("Sync metadata, no new kernel metadata");
1169                 /* No new metadata, exit. */
1170                 ret = ENODATA;
1171                 goto end;
1172         }
1173
1174 end:
1175         return ret;
1176 }
1177
1178 static
1179 int update_stream_stats(struct lttng_consumer_stream *stream)
1180 {
1181         int ret;
1182         uint64_t seq, discarded;
1183
1184         ret = kernctl_get_sequence_number(stream->wait_fd, &seq);
1185         if (ret < 0) {
1186                 if (ret == -ENOTTY) {
1187                         /* Command not implemented by lttng-modules. */
1188                         seq = -1ULL;
1189                         ret = 0;
1190                 } else {
1191                         PERROR("kernctl_get_sequence_number");
1192                         goto end;
1193                 }
1194         }
1195
1196         /*
1197          * Start the sequence when we extract the first packet in case we don't
1198          * start at 0 (for example if a consumer is not connected to the
1199          * session immediately after the beginning).
1200          */
1201         if (stream->last_sequence_number == -1ULL) {
1202                 stream->last_sequence_number = seq;
1203         } else if (seq > stream->last_sequence_number) {
1204                 stream->chan->lost_packets += seq -
1205                                 stream->last_sequence_number - 1;
1206         } else {
1207                 /* seq <= last_sequence_number */
1208                 ERR("Sequence number inconsistent : prev = %" PRIu64
1209                                 ", current = %" PRIu64,
1210                                 stream->last_sequence_number, seq);
1211                 ret = -1;
1212                 goto end;
1213         }
1214         stream->last_sequence_number = seq;
1215
1216         ret = kernctl_get_events_discarded(stream->wait_fd, &discarded);
1217         if (ret < 0) {
1218                 PERROR("kernctl_get_events_discarded");
1219                 goto end;
1220         }
1221         if (discarded < stream->last_discarded_events) {
1222                 /*
1223                  * Overflow has occurred. We assume only one wrap-around
1224                  * has occurred.
1225                  */
1226                 stream->chan->discarded_events += (1ULL << (CAA_BITS_PER_LONG - 1)) -
1227                         stream->last_discarded_events + discarded;
1228         } else {
1229                 stream->chan->discarded_events += discarded -
1230                         stream->last_discarded_events;
1231         }
1232         stream->last_discarded_events = discarded;
1233         ret = 0;
1234
1235 end:
1236         return ret;
1237 }
1238
1239 /*
1240  * Check if the local version of the metadata stream matches with the version
1241  * of the metadata stream in the kernel. If it was updated, set the reset flag
1242  * on the stream.
1243  */
1244 static
1245 int metadata_stream_check_version(int infd, struct lttng_consumer_stream *stream)
1246 {
1247         int ret;
1248         uint64_t cur_version;
1249
1250         ret = kernctl_get_metadata_version(infd, &cur_version);
1251         if (ret < 0) {
1252                 if (ret == -ENOTTY) {
1253                         /*
1254                          * LTTng-modules does not implement this
1255                          * command.
1256                          */
1257                         ret = 0;
1258                         goto end;
1259                 }
1260                 ERR("Failed to get the metadata version");
1261                 goto end;
1262         }
1263
1264         if (stream->metadata_version == cur_version) {
1265                 ret = 0;
1266                 goto end;
1267         }
1268
1269         DBG("New metadata version detected");
1270         stream->metadata_version = cur_version;
1271         stream->reset_metadata_flag = 1;
1272         ret = 0;
1273
1274 end:
1275         return ret;
1276 }
1277
1278 /*
1279  * Consume data on a file descriptor and write it on a trace file.
1280  */
1281 ssize_t lttng_kconsumer_read_subbuffer(struct lttng_consumer_stream *stream,
1282                 struct lttng_consumer_local_data *ctx)
1283 {
1284         unsigned long len, subbuf_size, padding;
1285         int err, write_index = 1;
1286         ssize_t ret = 0;
1287         int infd = stream->wait_fd;
1288         struct ctf_packet_index index;
1289
1290         DBG("In read_subbuffer (infd : %d)", infd);
1291
1292         /* Get the next subbuffer */
1293         err = kernctl_get_next_subbuf(infd);
1294         if (err != 0) {
1295                 /*
1296                  * This is a debug message even for single-threaded consumer,
1297                  * because poll() have more relaxed criterions than get subbuf,
1298                  * so get_subbuf may fail for short race windows where poll()
1299                  * would issue wakeups.
1300                  */
1301                 DBG("Reserving sub buffer failed (everything is normal, "
1302                                 "it is due to concurrency)");
1303                 ret = err;
1304                 goto end;
1305         }
1306
1307         /* Get the full subbuffer size including padding */
1308         err = kernctl_get_padded_subbuf_size(infd, &len);
1309         if (err != 0) {
1310                 PERROR("Getting sub-buffer len failed.");
1311                 err = kernctl_put_subbuf(infd);
1312                 if (err != 0) {
1313                         if (err == -EFAULT) {
1314                                 PERROR("Error in unreserving sub buffer\n");
1315                         } else if (err == -EIO) {
1316                                 /* Should never happen with newer LTTng versions */
1317                                 PERROR("Reader has been pushed by the writer, last sub-buffer corrupted.");
1318                         }
1319                         ret = err;
1320                         goto end;
1321                 }
1322                 ret = err;
1323                 goto end;
1324         }
1325
1326         if (!stream->metadata_flag) {
1327                 ret = get_index_values(&index, infd);
1328                 if (ret < 0) {
1329                         err = kernctl_put_subbuf(infd);
1330                         if (err != 0) {
1331                                 if (err == -EFAULT) {
1332                                         PERROR("Error in unreserving sub buffer\n");
1333                                 } else if (err == -EIO) {
1334                                         /* Should never happen with newer LTTng versions */
1335                                         PERROR("Reader has been pushed by the writer, last sub-buffer corrupted.");
1336                                 }
1337                                 ret = err;
1338                                 goto end;
1339                         }
1340                         goto end;
1341                 }
1342                 ret = update_stream_stats(stream);
1343                 if (ret < 0) {
1344                         err = kernctl_put_subbuf(infd);
1345                         if (err != 0) {
1346                                 if (err == -EFAULT) {
1347                                         PERROR("Error in unreserving sub buffer\n");
1348                                 } else if (err == -EIO) {
1349                                         /* Should never happen with newer LTTng versions */
1350                                         PERROR("Reader has been pushed by the writer, last sub-buffer corrupted.");
1351                                 }
1352                                 ret = err;
1353                                 goto end;
1354                         }
1355                         goto end;
1356                 }
1357         } else {
1358                 write_index = 0;
1359                 ret = metadata_stream_check_version(infd, stream);
1360                 if (ret < 0) {
1361                         err = kernctl_put_subbuf(infd);
1362                         if (err != 0) {
1363                                 if (err == -EFAULT) {
1364                                         PERROR("Error in unreserving sub buffer\n");
1365                                 } else if (err == -EIO) {
1366                                         /* Should never happen with newer LTTng versions */
1367                                         PERROR("Reader has been pushed by the writer, last sub-buffer corrupted.");
1368                                 }
1369                                 ret = err;
1370                                 goto end;
1371                         }
1372                         goto end;
1373                 }
1374         }
1375
1376         switch (stream->chan->output) {
1377         case CONSUMER_CHANNEL_SPLICE:
1378                 /*
1379                  * XXX: The lttng-modules splice "actor" does not handle copying
1380                  * partial pages hence only using the subbuffer size without the
1381                  * padding makes the splice fail.
1382                  */
1383                 subbuf_size = len;
1384                 padding = 0;
1385
1386                 /* splice the subbuffer to the tracefile */
1387                 ret = lttng_consumer_on_read_subbuffer_splice(ctx, stream, subbuf_size,
1388                                 padding, &index);
1389                 /*
1390                  * XXX: Splice does not support network streaming so the return value
1391                  * is simply checked against subbuf_size and not like the mmap() op.
1392                  */
1393                 if (ret != subbuf_size) {
1394                         /*
1395                          * display the error but continue processing to try
1396                          * to release the subbuffer
1397                          */
1398                         ERR("Error splicing to tracefile (ret: %zd != len: %lu)",
1399                                         ret, subbuf_size);
1400                         write_index = 0;
1401                 }
1402                 break;
1403         case CONSUMER_CHANNEL_MMAP:
1404                 /* Get subbuffer size without padding */
1405                 err = kernctl_get_subbuf_size(infd, &subbuf_size);
1406                 if (err != 0) {
1407                         PERROR("Getting sub-buffer len failed.");
1408                         err = kernctl_put_subbuf(infd);
1409                         if (err != 0) {
1410                                 if (err == -EFAULT) {
1411                                         PERROR("Error in unreserving sub buffer\n");
1412                                 } else if (err == -EIO) {
1413                                         /* Should never happen with newer LTTng versions */
1414                                         PERROR("Reader has been pushed by the writer, last sub-buffer corrupted.");
1415                                 }
1416                                 ret = err;
1417                                 goto end;
1418                         }
1419                         ret = err;
1420                         goto end;
1421                 }
1422
1423                 /* Make sure the tracer is not gone mad on us! */
1424                 assert(len >= subbuf_size);
1425
1426                 padding = len - subbuf_size;
1427
1428                 /* write the subbuffer to the tracefile */
1429                 ret = lttng_consumer_on_read_subbuffer_mmap(ctx, stream, subbuf_size,
1430                                 padding, &index);
1431                 /*
1432                  * The mmap operation should write subbuf_size amount of data when
1433                  * network streaming or the full padding (len) size when we are _not_
1434                  * streaming.
1435                  */
1436                 if ((ret != subbuf_size && stream->net_seq_idx != (uint64_t) -1ULL) ||
1437                                 (ret != len && stream->net_seq_idx == (uint64_t) -1ULL)) {
1438                         /*
1439                          * Display the error but continue processing to try to release the
1440                          * subbuffer. This is a DBG statement since this is possible to
1441                          * happen without being a critical error.
1442                          */
1443                         DBG("Error writing to tracefile "
1444                                         "(ret: %zd != len: %lu != subbuf_size: %lu)",
1445                                         ret, len, subbuf_size);
1446                         write_index = 0;
1447                 }
1448                 break;
1449         default:
1450                 ERR("Unknown output method");
1451                 ret = -EPERM;
1452         }
1453
1454         err = kernctl_put_next_subbuf(infd);
1455         if (err != 0) {
1456                 if (err == -EFAULT) {
1457                         PERROR("Error in unreserving sub buffer\n");
1458                 } else if (err == -EIO) {
1459                         /* Should never happen with newer LTTng versions */
1460                         PERROR("Reader has been pushed by the writer, last sub-buffer corrupted.");
1461                 }
1462                 ret = err;
1463                 goto end;
1464         }
1465
1466         /* Write index if needed. */
1467         if (!write_index) {
1468                 goto end;
1469         }
1470
1471         if (stream->chan->live_timer_interval && !stream->metadata_flag) {
1472                 /*
1473                  * In live, block until all the metadata is sent.
1474                  */
1475                 pthread_mutex_lock(&stream->metadata_timer_lock);
1476                 assert(!stream->missed_metadata_flush);
1477                 stream->waiting_on_metadata = true;
1478                 pthread_mutex_unlock(&stream->metadata_timer_lock);
1479
1480                 err = consumer_stream_sync_metadata(ctx, stream->session_id);
1481
1482                 pthread_mutex_lock(&stream->metadata_timer_lock);
1483                 stream->waiting_on_metadata = false;
1484                 if (stream->missed_metadata_flush) {
1485                         stream->missed_metadata_flush = false;
1486                         pthread_mutex_unlock(&stream->metadata_timer_lock);
1487                         (void) consumer_flush_kernel_index(stream);
1488                 } else {
1489                         pthread_mutex_unlock(&stream->metadata_timer_lock);
1490                 }
1491                 if (err < 0) {
1492                         goto end;
1493                 }
1494         }
1495
1496         err = consumer_stream_write_index(stream, &index);
1497         if (err < 0) {
1498                 goto end;
1499         }
1500
1501 end:
1502         return ret;
1503 }
1504
1505 int lttng_kconsumer_on_recv_stream(struct lttng_consumer_stream *stream)
1506 {
1507         int ret;
1508
1509         assert(stream);
1510
1511         /*
1512          * Don't create anything if this is set for streaming or should not be
1513          * monitored.
1514          */
1515         if (stream->net_seq_idx == (uint64_t) -1ULL && stream->chan->monitor) {
1516                 ret = utils_create_stream_file(stream->chan->pathname, stream->name,
1517                                 stream->chan->tracefile_size, stream->tracefile_count_current,
1518                                 stream->uid, stream->gid, NULL);
1519                 if (ret < 0) {
1520                         goto error;
1521                 }
1522                 stream->out_fd = ret;
1523                 stream->tracefile_size_current = 0;
1524
1525                 if (!stream->metadata_flag) {
1526                         struct lttng_index_file *index_file;
1527
1528                         index_file = lttng_index_file_create(stream->chan->pathname,
1529                                         stream->name, stream->uid, stream->gid,
1530                                         stream->chan->tracefile_size,
1531                                         stream->tracefile_count_current,
1532                                         CTF_INDEX_MAJOR, CTF_INDEX_MINOR);
1533                         if (!index_file) {
1534                                 goto error;
1535                         }
1536                         stream->index_file = index_file;
1537                 }
1538         }
1539
1540         if (stream->output == LTTNG_EVENT_MMAP) {
1541                 /* get the len of the mmap region */
1542                 unsigned long mmap_len;
1543
1544                 ret = kernctl_get_mmap_len(stream->wait_fd, &mmap_len);
1545                 if (ret != 0) {
1546                         PERROR("kernctl_get_mmap_len");
1547                         goto error_close_fd;
1548                 }
1549                 stream->mmap_len = (size_t) mmap_len;
1550
1551                 stream->mmap_base = mmap(NULL, stream->mmap_len, PROT_READ,
1552                                 MAP_PRIVATE, stream->wait_fd, 0);
1553                 if (stream->mmap_base == MAP_FAILED) {
1554                         PERROR("Error mmaping");
1555                         ret = -1;
1556                         goto error_close_fd;
1557                 }
1558         }
1559
1560         /* we return 0 to let the library handle the FD internally */
1561         return 0;
1562
1563 error_close_fd:
1564         if (stream->out_fd >= 0) {
1565                 int err;
1566
1567                 err = close(stream->out_fd);
1568                 assert(!err);
1569                 stream->out_fd = -1;
1570         }
1571 error:
1572         return ret;
1573 }
1574
1575 /*
1576  * Check if data is still being extracted from the buffers for a specific
1577  * stream. Consumer data lock MUST be acquired before calling this function
1578  * and the stream lock.
1579  *
1580  * Return 1 if the traced data are still getting read else 0 meaning that the
1581  * data is available for trace viewer reading.
1582  */
1583 int lttng_kconsumer_data_pending(struct lttng_consumer_stream *stream)
1584 {
1585         int ret;
1586
1587         assert(stream);
1588
1589         if (stream->endpoint_status != CONSUMER_ENDPOINT_ACTIVE) {
1590                 ret = 0;
1591                 goto end;
1592         }
1593
1594         ret = kernctl_get_next_subbuf(stream->wait_fd);
1595         if (ret == 0) {
1596                 /* There is still data so let's put back this subbuffer. */
1597                 ret = kernctl_put_subbuf(stream->wait_fd);
1598                 assert(ret == 0);
1599                 ret = 1;   /* Data is pending */
1600                 goto end;
1601         }
1602
1603         /* Data is NOT pending and ready to be read. */
1604         ret = 0;
1605
1606 end:
1607         return ret;
1608 }