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

   1 /*
   2  * Copyright (C) 2011 - Julien Desfossez <julien.desfossez@polymtl.ca>
   3  *                      Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License, version 2 only,
   7  * as published by the Free Software Foundation.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License along
  15  * with this program; if not, write to the Free Software Foundation, Inc.,
  16  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  17  */
  18
  19 #define _LGPL_SOURCE
  20 #include <assert.h>
  21 #include <poll.h>
  22 #include <pthread.h>
  23 #include <stdlib.h>
  24 #include <string.h>
  25 #include <sys/mman.h>
  26 #include <sys/socket.h>
  27 #include <sys/types.h>
  28 #include <inttypes.h>
  29 #include <unistd.h>
  30 #include <sys/stat.h>
  31
  32 #include <bin/lttng-consumerd/health-consumerd.h>
  33 #include <common/common.h>
  34 #include <common/kernel-ctl/kernel-ctl.h>
  35 #include <common/sessiond-comm/sessiond-comm.h>
  36 #include <common/sessiond-comm/relayd.h>
  37 #include <common/compat/fcntl.h>
  38 #include <common/compat/endian.h>
  39 #include <common/pipe.h>
  40 #include <common/relayd/relayd.h>
  41 #include <common/utils.h>
  42 #include <common/consumer/consumer-stream.h>
  43 #include <common/index/index.h>
  44 #include <common/consumer/consumer-timer.h>
  45
  46 #include "kernel-consumer.h"
  47
  48 extern struct lttng_consumer_global_data consumer_data;
  49 extern int consumer_poll_timeout;
  50 extern volatile int consumer_quit;
  51
  52 /*
  53  * Take a snapshot for a specific fd
  54  *
  55  * Returns 0 on success, < 0 on error
  56  */
  57 int lttng_kconsumer_take_snapshot(struct lttng_consumer_stream *stream)
  58 {
  59         int ret = 0;
  60         int infd = stream->wait_fd;
  61
  62         ret = kernctl_snapshot(infd);
  63         if (ret != 0) {
  64                 PERROR("Getting sub-buffer snapshot.");
  65                 ret = -errno;
  66         }
  67
  68         return ret;
  69 }
  70
  71 /*
  72  * Get the produced position
  73  *
  74  * Returns 0 on success, < 0 on error
  75  */
  76 int lttng_kconsumer_get_produced_snapshot(struct lttng_consumer_stream *stream,
  77                 unsigned long *pos)
  78 {
  79         int ret;
  80         int infd = stream->wait_fd;
  81
  82         ret = kernctl_snapshot_get_produced(infd, pos);
  83         if (ret != 0) {
  84                 PERROR("kernctl_snapshot_get_produced");
  85                 ret = -errno;
  86         }
  87
  88         return ret;
  89 }
  90
  91 /*
  92  * Get the consumerd position
  93  *
  94  * Returns 0 on success, < 0 on error
  95  */
  96 int lttng_kconsumer_get_consumed_snapshot(struct lttng_consumer_stream *stream,
  97                 unsigned long *pos)
  98 {
  99         int ret;
 100         int infd = stream->wait_fd;
 101
 102         ret = kernctl_snapshot_get_consumed(infd, pos);
 103         if (ret != 0) {
 104                 PERROR("kernctl_snapshot_get_consumed");
 105                 ret = -errno;
 106         }
 107
 108         return ret;
 109 }
 110
 111 /*
 112  * Take a snapshot of all the stream of a channel
 113  *
 114  * Returns 0 on success, < 0 on error
 115  */
 116 int lttng_kconsumer_snapshot_channel(uint64_t key, char *path,
 117                 uint64_t relayd_id, uint64_t nb_packets_per_stream,
 118                 struct lttng_consumer_local_data *ctx)
 119 {
 120         int ret;
 121         struct lttng_consumer_channel *channel;
 122         struct lttng_consumer_stream *stream;
 123
 124         DBG("Kernel consumer snapshot channel %" PRIu64, key);
 125
 126         rcu_read_lock();
 127
 128         channel = consumer_find_channel(key);
 129         if (!channel) {
 130                 ERR("No channel found for key %" PRIu64, key);
 131                 ret = -1;
 132                 goto end;
 133         }
 134
 135         /* Splice is not supported yet for channel snapshot. */
 136         if (channel->output != CONSUMER_CHANNEL_MMAP) {
 137                 ERR("Unsupported output %d", channel->output);
 138                 ret = -1;
 139                 goto end;
 140         }
 141
 142         cds_list_for_each_entry(stream, &channel->streams.head, send_node) {
 143                 /* Are we at a position _before_ the first available packet ? */
 144                 bool before_first_packet = true;
 145                 unsigned long consumed_pos, produced_pos;
 146
 147                 health_code_update();
 148
 149                 /*
 150                  * Lock stream because we are about to change its state.
 151                  */
 152                 pthread_mutex_lock(&stream->lock);
 153
 154                 /*
 155                  * Assign the received relayd ID so we can use it for streaming. The streams
 156                  * are not visible to anyone so this is OK to change it.
 157                  */
 158                 stream->net_seq_idx = relayd_id;
 159                 channel->relayd_id = relayd_id;
 160                 if (relayd_id != (uint64_t) -1ULL) {
 161                         ret = consumer_send_relayd_stream(stream, path);
 162                         if (ret < 0) {
 163                                 ERR("sending stream to relayd");
 164                                 goto end_unlock;
 165                         }
 166                 } else {
 167                         ret = utils_create_stream_file(path, stream->name,
 168                                         stream->chan->tracefile_size,
 169                                         stream->tracefile_count_current,
 170                                         stream->uid, stream->gid, NULL);
 171                         if (ret < 0) {
 172                                 ERR("utils_create_stream_file");
 173                                 goto end_unlock;
 174                         }
 175
 176                         stream->out_fd = ret;
 177                         stream->tracefile_size_current = 0;
 178
 179                         DBG("Kernel consumer snapshot stream %s/%s (%" PRIu64 ")",
 180                                         path, stream->name, stream->key);
 181                 }
 182                 if (relayd_id != -1ULL) {
 183                         ret = consumer_send_relayd_streams_sent(relayd_id);
 184                         if (ret < 0) {
 185                                 ERR("sending streams sent to relayd");
 186                                 goto end_unlock;
 187                         }
 188                         channel->streams_sent_to_relayd = true;
 189                 }
 190
 191                 ret = kernctl_buffer_flush(stream->wait_fd);
 192                 if (ret < 0) {
 193                         ERR("Failed to flush kernel stream");
 194                         ret = -errno;
 195                         goto end_unlock;
 196                 }
 197
 198                 ret = lttng_kconsumer_take_snapshot(stream);
 199                 if (ret < 0) {
 200                         ERR("Taking kernel snapshot");
 201                         goto end_unlock;
 202                 }
 203
 204                 ret = lttng_kconsumer_get_produced_snapshot(stream, &produced_pos);
 205                 if (ret < 0) {
 206                         ERR("Produced kernel snapshot position");
 207                         goto end_unlock;
 208                 }
 209
 210                 ret = lttng_kconsumer_get_consumed_snapshot(stream, &consumed_pos);
 211                 if (ret < 0) {
 212                         ERR("Consumerd kernel snapshot position");
 213                         goto end_unlock;
 214                 }
 215
 216                 if (stream->max_sb_size == 0) {
 217                         ret = kernctl_get_max_subbuf_size(stream->wait_fd,
 218                                         &stream->max_sb_size);
 219                         if (ret < 0) {
 220                                 ERR("Getting kernel max_sb_size");
 221                                 ret = -errno;
 222                                 goto end_unlock;
 223                         }
 224                 }
 225
 226                 consumed_pos = consumer_get_consume_start_pos(consumed_pos,
 227                                 produced_pos, nb_packets_per_stream,
 228                                 stream->max_sb_size);
 229
 230                 while (consumed_pos < produced_pos) {
 231                         ssize_t read_len;
 232                         unsigned long len, padded_len;
 233                         int lost_packet = 0;
 234
 235                         health_code_update();
 236
 237                         DBG("Kernel consumer taking snapshot at pos %lu", consumed_pos);
 238
 239                         ret = kernctl_get_subbuf(stream->wait_fd, &consumed_pos);
 240                         if (ret < 0) {
 241                                 if (errno != EAGAIN) {
 242                                         PERROR("kernctl_get_subbuf snapshot");
 243                                         ret = -errno;
 244                                         goto end_unlock;
 245                                 }
 246                                 DBG("Kernel consumer get subbuf failed. Skipping it.");
 247                                 consumed_pos += stream->max_sb_size;
 248
 249                                 /*
 250                                  * Start accounting lost packets only when we
 251                                  * already have extracted packets (to match the
 252                                  * content of the final snapshot).
 253                                  */
 254                                 if (!before_first_packet) {
 255                                         lost_packet = 1;
 256                                 }
 257                                 continue;
 258                         }
 259
 260                         ret = kernctl_get_subbuf_size(stream->wait_fd, &len);
 261                         if (ret < 0) {
 262                                 ERR("Snapshot kernctl_get_subbuf_size");
 263                                 ret = -errno;
 264                                 goto error_put_subbuf;
 265                         }
 266
 267                         ret = kernctl_get_padded_subbuf_size(stream->wait_fd, &padded_len);
 268                         if (ret < 0) {
 269                                 ERR("Snapshot kernctl_get_padded_subbuf_size");
 270                                 ret = -errno;
 271                                 goto error_put_subbuf;
 272                         }
 273
 274                         read_len = lttng_consumer_on_read_subbuffer_mmap(ctx, stream, len,
 275                                         padded_len - len, NULL);
 276                         /*
 277                          * We write the padded len in local tracefiles but the data len
 278                          * when using a relay. Display the error but continue processing
 279                          * to try to release the subbuffer.
 280                          */
 281                         if (relayd_id != (uint64_t) -1ULL) {
 282                                 if (read_len != len) {
 283                                         ERR("Error sending to the relay (ret: %zd != len: %lu)",
 284                                                         read_len, len);
 285                                 }
 286                         } else {
 287                                 if (read_len != padded_len) {
 288                                         ERR("Error writing to tracefile (ret: %zd != len: %lu)",
 289                                                         read_len, padded_len);
 290                                 }
 291                         }
 292
 293                         ret = kernctl_put_subbuf(stream->wait_fd);
 294                         if (ret < 0) {
 295                                 ERR("Snapshot kernctl_put_subbuf");
 296                                 ret = -errno;
 297                                 goto end_unlock;
 298                         }
 299                         consumed_pos += stream->max_sb_size;
 300
 301                         /*
 302                          * Only account lost packets located between
 303                          * succesfully extracted packets (do not account before
 304                          * and after since they are not visible in the
 305                          * resulting snapshot).
 306                          */
 307                         stream->chan->lost_packets += lost_packet;
 308                         lost_packet = 0;
 309                         before_first_packet = false;
 310                 }
 311
 312                 if (relayd_id == (uint64_t) -1ULL) {
 313                         if (stream->out_fd >= 0) {
 314                                 ret = close(stream->out_fd);
 315                                 if (ret < 0) {
 316                                         PERROR("Kernel consumer snapshot close out_fd");
 317                                         goto end_unlock;
 318                                 }
 319                                 stream->out_fd = -1;
 320                         }
 321                 } else {
 322                         close_relayd_stream(stream);
 323                         stream->net_seq_idx = (uint64_t) -1ULL;
 324                 }
 325                 pthread_mutex_unlock(&stream->lock);
 326         }
 327
 328         /* All good! */
 329         ret = 0;
 330         goto end;
 331
 332 error_put_subbuf:
 333         ret = kernctl_put_subbuf(stream->wait_fd);
 334         if (ret < 0) {
 335                 ret = -errno;
 336                 ERR("Snapshot kernctl_put_subbuf error path");
 337         }
 338 end_unlock:
 339         pthread_mutex_unlock(&stream->lock);
 340 end:
 341         rcu_read_unlock();
 342         return ret;
 343 }
 344
 345 /*
 346  * Read the whole metadata available for a snapshot.
 347  *
 348  * Returns 0 on success, < 0 on error
 349  */
 350 int lttng_kconsumer_snapshot_metadata(uint64_t key, char *path,
 351                 uint64_t relayd_id, struct lttng_consumer_local_data *ctx)
 352 {
 353         int ret, use_relayd = 0;
 354         ssize_t ret_read;
 355         struct lttng_consumer_channel *metadata_channel;
 356         struct lttng_consumer_stream *metadata_stream;
 357
 358         assert(ctx);
 359
 360         DBG("Kernel consumer snapshot metadata with key %" PRIu64 " at path %s",
 361                         key, path);
 362
 363         rcu_read_lock();
 364
 365         metadata_channel = consumer_find_channel(key);
 366         if (!metadata_channel) {
 367                 ERR("Kernel snapshot metadata not found for key %" PRIu64, key);
 368                 ret = -1;
 369                 goto error;
 370         }
 371
 372         metadata_stream = metadata_channel->metadata_stream;
 373         assert(metadata_stream);
 374
 375         /* Flag once that we have a valid relayd for the stream. */
 376         if (relayd_id != (uint64_t) -1ULL) {
 377                 use_relayd = 1;
 378         }
 379
 380         if (use_relayd) {
 381                 ret = consumer_send_relayd_stream(metadata_stream, path);
 382                 if (ret < 0) {
 383                         goto error;
 384                 }
 385         } else {
 386                 ret = utils_create_stream_file(path, metadata_stream->name,
 387                                 metadata_stream->chan->tracefile_size,
 388                                 metadata_stream->tracefile_count_current,
 389                                 metadata_stream->uid, metadata_stream->gid, NULL);
 390                 if (ret < 0) {
 391                         goto error;
 392                 }
 393                 metadata_stream->out_fd = ret;
 394         }
 395
 396         do {
 397                 health_code_update();
 398
 399                 ret_read = lttng_kconsumer_read_subbuffer(metadata_stream, ctx);
 400                 if (ret_read < 0) {
 401                         if (ret_read != -EAGAIN) {
 402                                 ERR("Kernel snapshot reading metadata subbuffer (ret: %zd)",
 403                                                 ret_read);
 404                                 goto error;
 405                         }
 406                         /* ret_read is negative at this point so we will exit the loop. */
 407                         continue;
 408                 }
 409         } while (ret_read >= 0);
 410
 411         if (use_relayd) {
 412                 close_relayd_stream(metadata_stream);
 413                 metadata_stream->net_seq_idx = (uint64_t) -1ULL;
 414         } else {
 415                 if (metadata_stream->out_fd >= 0) {
 416                         ret = close(metadata_stream->out_fd);
 417                         if (ret < 0) {
 418                                 PERROR("Kernel consumer snapshot metadata close out_fd");
 419                                 /*
 420                                  * Don't go on error here since the snapshot was successful at this
 421                                  * point but somehow the close failed.
 422                                  */
 423                         }
 424                         metadata_stream->out_fd = -1;
 425                 }
 426         }
 427
 428         ret = 0;
 429
 430         cds_list_del(&metadata_stream->send_node);
 431         consumer_stream_destroy(metadata_stream, NULL);
 432         metadata_channel->metadata_stream = NULL;
 433 error:
 434         rcu_read_unlock();
 435         return ret;
 436 }
 437
 438 /*
 439  * Receive command from session daemon and process it.
 440  *
 441  * Return 1 on success else a negative value or 0.
 442  */
 443 int lttng_kconsumer_recv_cmd(struct lttng_consumer_local_data *ctx,
 444                 int sock, struct pollfd *consumer_sockpoll)
 445 {
 446         ssize_t ret;
 447         enum lttcomm_return_code ret_code = LTTCOMM_CONSUMERD_SUCCESS;
 448         struct lttcomm_consumer_msg msg;
 449
 450         health_code_update();
 451
 452         ret = lttcomm_recv_unix_sock(sock, &msg, sizeof(msg));
 453         if (ret != sizeof(msg)) {
 454                 if (ret > 0) {
 455                         lttng_consumer_send_error(ctx, LTTCOMM_CONSUMERD_ERROR_RECV_CMD);
 456                         ret = -1;
 457                 }
 458                 return ret;
 459         }
 460
 461         health_code_update();
 462
 463         /* Deprecated command */
 464         assert(msg.cmd_type != LTTNG_CONSUMER_STOP);
 465
 466         health_code_update();
 467
 468         /* relayd needs RCU read-side protection */
 469         rcu_read_lock();
 470
 471         switch (msg.cmd_type) {
 472         case LTTNG_CONSUMER_ADD_RELAYD_SOCKET:
 473         {
 474                 /* Session daemon status message are handled in the following call. */
 475                 ret = consumer_add_relayd_socket(msg.u.relayd_sock.net_index,
 476                                 msg.u.relayd_sock.type, ctx, sock, consumer_sockpoll,
 477                                 &msg.u.relayd_sock.sock, msg.u.relayd_sock.session_id,
 478                                  msg.u.relayd_sock.relayd_session_id);
 479                 goto end_nosignal;
 480         }
 481         case LTTNG_CONSUMER_ADD_CHANNEL:
 482         {
 483                 struct lttng_consumer_channel *new_channel;
 484                 int ret_recv;
 485
 486                 health_code_update();
 487
 488                 /* First send a status message before receiving the fds. */
 489                 ret = consumer_send_status_msg(sock, ret_code);
 490                 if (ret < 0) {
 491                         /* Somehow, the session daemon is not responding anymore. */
 492                         goto error_fatal;
 493                 }
 494
 495                 health_code_update();
 496
 497                 DBG("consumer_add_channel %" PRIu64, msg.u.channel.channel_key);
 498                 new_channel = consumer_allocate_channel(msg.u.channel.channel_key,
 499                                 msg.u.channel.session_id, msg.u.channel.pathname,
 500                                 msg.u.channel.name, msg.u.channel.uid, msg.u.channel.gid,
 501                                 msg.u.channel.relayd_id, msg.u.channel.output,
 502                                 msg.u.channel.tracefile_size,
 503                                 msg.u.channel.tracefile_count, 0,
 504                                 msg.u.channel.monitor,
 505                                 msg.u.channel.live_timer_interval,
 506                                 NULL, NULL);
 507                 if (new_channel == NULL) {
 508                         lttng_consumer_send_error(ctx, LTTCOMM_CONSUMERD_OUTFD_ERROR);
 509                         goto end_nosignal;
 510                 }
 511                 new_channel->nb_init_stream_left = msg.u.channel.nb_init_streams;
 512                 switch (msg.u.channel.output) {
 513                 case LTTNG_EVENT_SPLICE:
 514                         new_channel->output = CONSUMER_CHANNEL_SPLICE;
 515                         break;
 516                 case LTTNG_EVENT_MMAP:
 517                         new_channel->output = CONSUMER_CHANNEL_MMAP;
 518                         break;
 519                 default:
 520                         ERR("Channel output unknown %d", msg.u.channel.output);
 521                         goto end_nosignal;
 522                 }
 523
 524                 /* Translate and save channel type. */
 525                 switch (msg.u.channel.type) {
 526                 case CONSUMER_CHANNEL_TYPE_DATA:
 527                 case CONSUMER_CHANNEL_TYPE_METADATA:
 528                         new_channel->type = msg.u.channel.type;
 529                         break;
 530                 default:
 531                         assert(0);
 532                         goto end_nosignal;
 533                 };
 534
 535                 health_code_update();
 536
 537                 if (ctx->on_recv_channel != NULL) {
 538                         ret_recv = ctx->on_recv_channel(new_channel);
 539                         if (ret_recv == 0) {
 540                                 ret = consumer_add_channel(new_channel, ctx);
 541                         } else if (ret_recv < 0) {
 542                                 goto end_nosignal;
 543                         }
 544                 } else {
 545                         ret = consumer_add_channel(new_channel, ctx);
 546                 }
 547                 if (CONSUMER_CHANNEL_TYPE_DATA) {
 548                         consumer_timer_live_start(new_channel,
 549                                         msg.u.channel.live_timer_interval);
 550                 }
 551
 552                 health_code_update();
 553
 554                 /* If we received an error in add_channel, we need to report it. */
 555                 if (ret < 0) {
 556                         ret = consumer_send_status_msg(sock, ret);
 557                         if (ret < 0) {
 558                                 goto error_fatal;
 559                         }
 560                         goto end_nosignal;
 561                 }
 562
 563                 goto end_nosignal;
 564         }
 565         case LTTNG_CONSUMER_ADD_STREAM:
 566         {
 567                 int fd;
 568                 struct lttng_pipe *stream_pipe;
 569                 struct lttng_consumer_stream *new_stream;
 570                 struct lttng_consumer_channel *channel;
 571                 int alloc_ret = 0;
 572
 573                 /*
 574                  * Get stream's channel reference. Needed when adding the stream to the
 575                  * global hash table.
 576                  */
 577                 channel = consumer_find_channel(msg.u.stream.channel_key);
 578                 if (!channel) {
 579                         /*
 580                          * We could not find the channel. Can happen if cpu hotplug
 581                          * happens while tearing down.
 582                          */
 583                         ERR("Unable to find channel key %" PRIu64, msg.u.stream.channel_key);
 584                         ret_code = LTTCOMM_CONSUMERD_CHAN_NOT_FOUND;
 585                 }
 586
 587                 health_code_update();
 588
 589                 /* First send a status message before receiving the fds. */
 590                 ret = consumer_send_status_msg(sock, ret_code);
 591                 if (ret < 0) {
 592                         /* Somehow, the session daemon is not responding anymore. */
 593                         goto error_fatal;
 594                 }
 595
 596                 health_code_update();
 597
 598                 if (ret_code != LTTCOMM_CONSUMERD_SUCCESS) {
 599                         /* Channel was not found. */
 600                         goto end_nosignal;
 601                 }
 602
 603                 /* Blocking call */
 604                 health_poll_entry();
 605                 ret = lttng_consumer_poll_socket(consumer_sockpoll);
 606                 health_poll_exit();
 607                 if (ret) {
 608                         goto error_fatal;
 609                 }
 610
 611                 health_code_update();
 612
 613                 /* Get stream file descriptor from socket */
 614                 ret = lttcomm_recv_fds_unix_sock(sock, &fd, 1);
 615                 if (ret != sizeof(fd)) {
 616                         lttng_consumer_send_error(ctx, LTTCOMM_CONSUMERD_ERROR_RECV_FD);
 617                         rcu_read_unlock();
 618                         return ret;
 619                 }
 620
 621                 health_code_update();
 622
 623                 /*
 624                  * Send status code to session daemon only if the recv works. If the
 625                  * above recv() failed, the session daemon is notified through the
 626                  * error socket and the teardown is eventually done.
 627                  */
 628                 ret = consumer_send_status_msg(sock, ret_code);
 629                 if (ret < 0) {
 630                         /* Somehow, the session daemon is not responding anymore. */
 631                         goto end_nosignal;
 632                 }
 633
 634                 health_code_update();
 635
 636                 new_stream = consumer_allocate_stream(channel->key,
 637                                 fd,
 638                                 LTTNG_CONSUMER_ACTIVE_STREAM,
 639                                 channel->name,
 640                                 channel->uid,
 641                                 channel->gid,
 642                                 channel->relayd_id,
 643                                 channel->session_id,
 644                                 msg.u.stream.cpu,
 645                                 &alloc_ret,
 646                                 channel->type,
 647                                 channel->monitor);
 648                 if (new_stream == NULL) {
 649                         switch (alloc_ret) {
 650                         case -ENOMEM:
 651                         case -EINVAL:
 652                         default:
 653                                 lttng_consumer_send_error(ctx, LTTCOMM_CONSUMERD_OUTFD_ERROR);
 654                                 break;
 655                         }
 656                         goto end_nosignal;
 657                 }
 658
 659                 new_stream->chan = channel;
 660                 new_stream->wait_fd = fd;
 661                 switch (channel->output) {
 662                 case CONSUMER_CHANNEL_SPLICE:
 663                         new_stream->output = LTTNG_EVENT_SPLICE;
 664                         ret = utils_create_pipe(new_stream->splice_pipe);
 665                         if (ret < 0) {
 666                                 goto end_nosignal;
 667                         }
 668                         break;
 669                 case CONSUMER_CHANNEL_MMAP:
 670                         new_stream->output = LTTNG_EVENT_MMAP;
 671                         break;
 672                 default:
 673                         ERR("Stream output unknown %d", channel->output);
 674                         goto end_nosignal;
 675                 }
 676
 677                 /*
 678                  * We've just assigned the channel to the stream so increment the
 679                  * refcount right now. We don't need to increment the refcount for
 680                  * streams in no monitor because we handle manually the cleanup of
 681                  * those. It is very important to make sure there is NO prior
 682                  * consumer_del_stream() calls or else the refcount will be unbalanced.
 683                  */
 684                 if (channel->monitor) {
 685                         uatomic_inc(&new_stream->chan->refcount);
 686                 }
 687
 688                 /*
 689                  * The buffer flush is done on the session daemon side for the kernel
 690                  * so no need for the stream "hangup_flush_done" variable to be
 691                  * tracked. This is important for a kernel stream since we don't rely
 692                  * on the flush state of the stream to read data. It's not the case for
 693                  * user space tracing.
 694                  */
 695                 new_stream->hangup_flush_done = 0;
 696
 697                 health_code_update();
 698
 699                 if (ctx->on_recv_stream) {
 700                         ret = ctx->on_recv_stream(new_stream);
 701                         if (ret < 0) {
 702                                 consumer_stream_free(new_stream);
 703                                 goto end_nosignal;
 704                         }
 705                 }
 706
 707                 health_code_update();
 708
 709                 if (new_stream->metadata_flag) {
 710                         channel->metadata_stream = new_stream;
 711                 }
 712
 713                 /* Do not monitor this stream. */
 714                 if (!channel->monitor) {
 715                         DBG("Kernel consumer add stream %s in no monitor mode with "
 716                                         "relayd id %" PRIu64, new_stream->name,
 717                                         new_stream->net_seq_idx);
 718                         cds_list_add(&new_stream->send_node, &channel->streams.head);
 719                         break;
 720                 }
 721
 722                 /* Send stream to relayd if the stream has an ID. */
 723                 if (new_stream->net_seq_idx != (uint64_t) -1ULL) {
 724                         ret = consumer_send_relayd_stream(new_stream,
 725                                         new_stream->chan->pathname);
 726                         if (ret < 0) {
 727                                 consumer_stream_free(new_stream);
 728                                 goto end_nosignal;
 729                         }
 730
 731                         /*
 732                          * If adding an extra stream to an already
 733                          * existing channel (e.g. cpu hotplug), we need
 734                          * to send the "streams_sent" command to relayd.
 735                          */
 736                         if (channel->streams_sent_to_relayd) {
 737                                 ret = consumer_send_relayd_streams_sent(
 738                                                 new_stream->net_seq_idx);
 739                                 if (ret < 0) {
 740                                         goto end_nosignal;
 741                                 }
 742                         }
 743                 }
 744
 745                 /* Get the right pipe where the stream will be sent. */
 746                 if (new_stream->metadata_flag) {
 747                         ret = consumer_add_metadata_stream(new_stream);
 748                         if (ret) {
 749                                 ERR("Consumer add metadata stream %" PRIu64 " failed. Continuing",
 750                                                 new_stream->key);
 751                                 consumer_stream_free(new_stream);
 752                                 goto end_nosignal;
 753                         }
 754                         stream_pipe = ctx->consumer_metadata_pipe;
 755                 } else {
 756                         ret = consumer_add_data_stream(new_stream);
 757                         if (ret) {
 758                                 ERR("Consumer add stream %" PRIu64 " failed. Continuing",
 759                                                 new_stream->key);
 760                                 consumer_stream_free(new_stream);
 761                                 goto end_nosignal;
 762                         }
 763                         stream_pipe = ctx->consumer_data_pipe;
 764                 }
 765
 766                 /* Vitible to other threads */
 767                 new_stream->globally_visible = 1;
 768
 769                 health_code_update();
 770
 771                 ret = lttng_pipe_write(stream_pipe, &new_stream, sizeof(new_stream));
 772                 if (ret < 0) {
 773                         ERR("Consumer write %s stream to pipe %d",
 774                                         new_stream->metadata_flag ? "metadata" : "data",
 775                                         lttng_pipe_get_writefd(stream_pipe));
 776                         if (new_stream->metadata_flag) {
 777                                 consumer_del_stream_for_metadata(new_stream);
 778                         } else {
 779                                 consumer_del_stream_for_data(new_stream);
 780                         }
 781                         goto end_nosignal;
 782                 }
 783
 784                 DBG("Kernel consumer ADD_STREAM %s (fd: %d) with relayd id %" PRIu64,
 785                                 new_stream->name, fd, new_stream->relayd_stream_id);
 786                 break;
 787         }
 788         case LTTNG_CONSUMER_STREAMS_SENT:
 789         {
 790                 struct lttng_consumer_channel *channel;
 791
 792                 /*
 793                  * Get stream's channel reference. Needed when adding the stream to the
 794                  * global hash table.
 795                  */
 796                 channel = consumer_find_channel(msg.u.sent_streams.channel_key);
 797                 if (!channel) {
 798                         /*
 799                          * We could not find the channel. Can happen if cpu hotplug
 800                          * happens while tearing down.
 801                          */
 802                         ERR("Unable to find channel key %" PRIu64,
 803                                         msg.u.sent_streams.channel_key);
 804                         ret_code = LTTCOMM_CONSUMERD_CHAN_NOT_FOUND;
 805                 }
 806
 807                 health_code_update();
 808
 809                 /*
 810                  * Send status code to session daemon.
 811                  */
 812                 ret = consumer_send_status_msg(sock, ret_code);
 813                 if (ret < 0 || ret_code != LTTCOMM_CONSUMERD_SUCCESS) {
 814                         /* Somehow, the session daemon is not responding anymore. */
 815                         goto end_nosignal;
 816                 }
 817
 818                 health_code_update();
 819
 820                 /*
 821                  * We should not send this message if we don't monitor the
 822                  * streams in this channel.
 823                  */
 824                 if (!channel->monitor) {
 825                         break;
 826                 }
 827
 828                 health_code_update();
 829                 /* Send stream to relayd if the stream has an ID. */
 830                 if (msg.u.sent_streams.net_seq_idx != (uint64_t) -1ULL) {
 831                         ret = consumer_send_relayd_streams_sent(
 832                                         msg.u.sent_streams.net_seq_idx);
 833                         if (ret < 0) {
 834                                 goto end_nosignal;
 835                         }
 836                         channel->streams_sent_to_relayd = true;
 837                 }
 838                 break;
 839         }
 840         case LTTNG_CONSUMER_UPDATE_STREAM:
 841         {
 842                 rcu_read_unlock();
 843                 return -ENOSYS;
 844         }
 845         case LTTNG_CONSUMER_DESTROY_RELAYD:
 846         {
 847                 uint64_t index = msg.u.destroy_relayd.net_seq_idx;
 848                 struct consumer_relayd_sock_pair *relayd;
 849
 850                 DBG("Kernel consumer destroying relayd %" PRIu64, index);
 851
 852                 /* Get relayd reference if exists. */
 853                 relayd = consumer_find_relayd(index);
 854                 if (relayd == NULL) {
 855                         DBG("Unable to find relayd %" PRIu64, index);
 856                         ret_code = LTTCOMM_CONSUMERD_RELAYD_FAIL;
 857                 }
 858
 859                 /*
 860                  * Each relayd socket pair has a refcount of stream attached to it
 861                  * which tells if the relayd is still active or not depending on the
 862                  * refcount value.
 863                  *
 864                  * This will set the destroy flag of the relayd object and destroy it
 865                  * if the refcount reaches zero when called.
 866                  *
 867                  * The destroy can happen either here or when a stream fd hangs up.
 868                  */
 869                 if (relayd) {
 870                         consumer_flag_relayd_for_destroy(relayd);
 871                 }
 872
 873                 health_code_update();
 874
 875                 ret = consumer_send_status_msg(sock, ret_code);
 876                 if (ret < 0) {
 877                         /* Somehow, the session daemon is not responding anymore. */
 878                         goto error_fatal;
 879                 }
 880
 881                 goto end_nosignal;
 882         }
 883         case LTTNG_CONSUMER_DATA_PENDING:
 884         {
 885                 int32_t ret;
 886                 uint64_t id = msg.u.data_pending.session_id;
 887
 888                 DBG("Kernel consumer data pending command for id %" PRIu64, id);
 889
 890                 ret = consumer_data_pending(id);
 891
 892                 health_code_update();
 893
 894                 /* Send back returned value to session daemon */
 895                 ret = lttcomm_send_unix_sock(sock, &ret, sizeof(ret));
 896                 if (ret < 0) {
 897                         PERROR("send data pending ret code");
 898                         goto error_fatal;
 899                 }
 900
 901                 /*
 902                  * No need to send back a status message since the data pending
 903                  * returned value is the response.
 904                  */
 905                 break;
 906         }
 907         case LTTNG_CONSUMER_SNAPSHOT_CHANNEL:
 908         {
 909                 if (msg.u.snapshot_channel.metadata == 1) {
 910                         ret = lttng_kconsumer_snapshot_metadata(msg.u.snapshot_channel.key,
 911                                         msg.u.snapshot_channel.pathname,
 912                                         msg.u.snapshot_channel.relayd_id, ctx);
 913                         if (ret < 0) {
 914                                 ERR("Snapshot metadata failed");
 915                                 ret_code = LTTCOMM_CONSUMERD_ERROR_METADATA;
 916                         }
 917                 } else {
 918                         ret = lttng_kconsumer_snapshot_channel(msg.u.snapshot_channel.key,
 919                                         msg.u.snapshot_channel.pathname,
 920                                         msg.u.snapshot_channel.relayd_id,
 921                                         msg.u.snapshot_channel.nb_packets_per_stream,
 922                                         ctx);
 923                         if (ret < 0) {
 924                                 ERR("Snapshot channel failed");
 925                                 ret_code = LTTCOMM_CONSUMERD_CHAN_NOT_FOUND;
 926                         }
 927                 }
 928
 929                 health_code_update();
 930
 931                 ret = consumer_send_status_msg(sock, ret_code);
 932                 if (ret < 0) {
 933                         /* Somehow, the session daemon is not responding anymore. */
 934                         goto end_nosignal;
 935                 }
 936                 break;
 937         }
 938         case LTTNG_CONSUMER_DESTROY_CHANNEL:
 939         {
 940                 uint64_t key = msg.u.destroy_channel.key;
 941                 struct lttng_consumer_channel *channel;
 942
 943                 channel = consumer_find_channel(key);
 944                 if (!channel) {
 945                         ERR("Kernel consumer destroy channel %" PRIu64 " not found", key);
 946                         ret_code = LTTCOMM_CONSUMERD_CHAN_NOT_FOUND;
 947                 }
 948
 949                 health_code_update();
 950
 951                 ret = consumer_send_status_msg(sock, ret_code);
 952                 if (ret < 0) {
 953                         /* Somehow, the session daemon is not responding anymore. */
 954                         goto end_nosignal;
 955                 }
 956
 957                 health_code_update();
 958
 959                 /* Stop right now if no channel was found. */
 960                 if (!channel) {
 961                         goto end_nosignal;
 962                 }
 963
 964                 /*
 965                  * This command should ONLY be issued for channel with streams set in
 966                  * no monitor mode.
 967                  */
 968                 assert(!channel->monitor);
 969
 970                 /*
 971                  * The refcount should ALWAYS be 0 in the case of a channel in no
 972                  * monitor mode.
 973                  */
 974                 assert(!uatomic_sub_return(&channel->refcount, 1));
 975
 976                 consumer_del_channel(channel);
 977
 978                 goto end_nosignal;
 979         }
 980         case LTTNG_CONSUMER_DISCARDED_EVENTS:
 981         {
 982                 uint64_t ret;
 983                 struct lttng_consumer_channel *channel;
 984                 uint64_t id = msg.u.discarded_events.session_id;
 985                 uint64_t key = msg.u.discarded_events.channel_key;
 986
 987                 DBG("Kernel consumer discarded events command for session id %"
 988                                 PRIu64 ", channel key %" PRIu64, id, key);
 989
 990                 channel = consumer_find_channel(key);
 991                 if (!channel) {
 992                         ERR("Kernel consumer discarded events channel %"
 993                                         PRIu64 " not found", key);
 994                         ret = 0;
 995                 } else {
 996                         ret = channel->discarded_events;
 997                 }
 998
 999                 health_code_update();
1000
1001                 /* Send back returned value to session daemon */
1002                 ret = lttcomm_send_unix_sock(sock, &ret, sizeof(ret));
1003                 if (ret < 0) {
1004                         PERROR("send discarded events");
1005                         goto error_fatal;
1006                 }
1007
1008                 break;
1009         }
1010         case LTTNG_CONSUMER_LOST_PACKETS:
1011         {
1012                 uint64_t ret;
1013                 struct lttng_consumer_channel *channel;
1014                 uint64_t id = msg.u.lost_packets.session_id;
1015                 uint64_t key = msg.u.lost_packets.channel_key;
1016
1017                 DBG("Kernel consumer lost packets command for session id %"
1018                                 PRIu64 ", channel key %" PRIu64, id, key);
1019
1020                 channel = consumer_find_channel(key);
1021                 if (!channel) {
1022                         ERR("Kernel consumer lost packets channel %"
1023                                         PRIu64 " not found", key);
1024                         ret = 0;
1025                 } else {
1026                         ret = channel->lost_packets;
1027                 }
1028
1029                 health_code_update();
1030
1031                 /* Send back returned value to session daemon */
1032                 ret = lttcomm_send_unix_sock(sock, &ret, sizeof(ret));
1033                 if (ret < 0) {
1034                         PERROR("send lost packets");
1035                         goto error_fatal;
1036                 }
1037
1038                 break;
1039         }
1040         default:
1041                 goto end_nosignal;
1042         }
1043
1044 end_nosignal:
1045         rcu_read_unlock();
1046
1047         /*
1048          * Return 1 to indicate success since the 0 value can be a socket
1049          * shutdown during the recv() or send() call.
1050          */
1051         health_code_update();
1052         return 1;
1053
1054 error_fatal:
1055         rcu_read_unlock();
1056         /* This will issue a consumer stop. */
1057         return -1;
1058 }
1059
1060 /*
1061  * Populate index values of a kernel stream. Values are set in big endian order.
1062  *
1063  * Return 0 on success or else a negative value.
1064  */
1065 static int get_index_values(struct ctf_packet_index *index, int infd)
1066 {
1067         int ret;
1068
1069         ret = kernctl_get_timestamp_begin(infd, &index->timestamp_begin);
1070         if (ret < 0) {
1071                 PERROR("kernctl_get_timestamp_begin");
1072                 goto error;
1073         }
1074         index->timestamp_begin = htobe64(index->timestamp_begin);
1075
1076         ret = kernctl_get_timestamp_end(infd, &index->timestamp_end);
1077         if (ret < 0) {
1078                 PERROR("kernctl_get_timestamp_end");
1079                 goto error;
1080         }
1081         index->timestamp_end = htobe64(index->timestamp_end);
1082
1083         ret = kernctl_get_events_discarded(infd, &index->events_discarded);
1084         if (ret < 0) {
1085                 PERROR("kernctl_get_events_discarded");
1086                 goto error;
1087         }
1088         index->events_discarded = htobe64(index->events_discarded);
1089
1090         ret = kernctl_get_content_size(infd, &index->content_size);
1091         if (ret < 0) {
1092                 PERROR("kernctl_get_content_size");
1093                 goto error;
1094         }
1095         index->content_size = htobe64(index->content_size);
1096
1097         ret = kernctl_get_packet_size(infd, &index->packet_size);
1098         if (ret < 0) {
1099                 PERROR("kernctl_get_packet_size");
1100                 goto error;
1101         }
1102         index->packet_size = htobe64(index->packet_size);
1103
1104         ret = kernctl_get_stream_id(infd, &index->stream_id);
1105         if (ret < 0) {
1106                 PERROR("kernctl_get_stream_id");
1107                 goto error;
1108         }
1109         index->stream_id = htobe64(index->stream_id);
1110
1111         ret = kernctl_get_instance_id(infd, &index->stream_instance_id);
1112         if (ret < 0) {
1113                 if (ret == -ENOTTY) {
1114                         /* Command not implemented by lttng-modules. */
1115                         index->stream_instance_id = -1ULL;
1116                         ret = 0;
1117                 } else {
1118                         PERROR("kernctl_get_instance_id");
1119                         goto error;
1120                 }
1121         }
1122         index->stream_instance_id = htobe64(index->stream_instance_id);
1123
1124         ret = kernctl_get_sequence_number(infd, &index->packet_seq_num);
1125         if (ret < 0) {
1126                 if (ret == -ENOTTY) {
1127                         /* Command not implemented by lttng-modules. */
1128                         index->packet_seq_num = -1ULL;
1129                         ret = 0;
1130                 } else {
1131                         PERROR("kernctl_get_sequence_number");
1132                         goto error;
1133                 }
1134         }
1135         index->packet_seq_num = htobe64(index->packet_seq_num);
1136
1137 error:
1138         return ret;
1139 }
1140 /*
1141  * Sync metadata meaning request them to the session daemon and snapshot to the
1142  * metadata thread can consumer them.
1143  *
1144  * Metadata stream lock MUST be acquired.
1145  *
1146  * Return 0 if new metadatda is available, EAGAIN if the metadata stream
1147  * is empty or a negative value on error.
1148  */
1149 int lttng_kconsumer_sync_metadata(struct lttng_consumer_stream *metadata)
1150 {
1151         int ret;
1152
1153         assert(metadata);
1154
1155         ret = kernctl_buffer_flush(metadata->wait_fd);
1156         if (ret < 0) {
1157                 ERR("Failed to flush kernel stream");
1158                 goto end;
1159         }
1160
1161         ret = kernctl_snapshot(metadata->wait_fd);
1162         if (ret < 0) {
1163                 if (errno != EAGAIN) {
1164                         ERR("Sync metadata, taking kernel snapshot failed.");
1165                         goto end;
1166                 }
1167                 DBG("Sync metadata, no new kernel metadata");
1168                 /* No new metadata, exit. */
1169                 ret = ENODATA;
1170                 goto end;
1171         }
1172
1173 end:
1174         return ret;
1175 }
1176
1177 static
1178 int update_stream_stats(struct lttng_consumer_stream *stream)
1179 {
1180         int ret;
1181         uint64_t seq, discarded;
1182
1183         ret = kernctl_get_sequence_number(stream->wait_fd, &seq);
1184         if (ret < 0) {
1185                 if (ret == -ENOTTY) {
1186                         /* Command not implemented by lttng-modules. */
1187                         seq = -1ULL;
1188                         ret = 0;
1189                 } else {
1190                         PERROR("kernctl_get_sequence_number");
1191                         goto end;
1192                 }
1193         }
1194
1195         /*
1196          * Start the sequence when we extract the first packet in case we don't
1197          * start at 0 (for example if a consumer is not connected to the
1198          * session immediately after the beginning).
1199          */
1200         if (stream->last_sequence_number == -1ULL) {
1201                 stream->last_sequence_number = seq;
1202         } else if (seq > stream->last_sequence_number) {
1203                 stream->chan->lost_packets += seq -
1204                                 stream->last_sequence_number - 1;
1205         } else {
1206                 /* seq <= last_sequence_number */
1207                 ERR("Sequence number inconsistent : prev = %" PRIu64
1208                                 ", current = %" PRIu64,
1209                                 stream->last_sequence_number, seq);
1210                 ret = -1;
1211                 goto end;
1212         }
1213         stream->last_sequence_number = seq;
1214
1215         ret = kernctl_get_events_discarded(stream->wait_fd, &discarded);
1216         if (ret < 0) {
1217                 PERROR("kernctl_get_events_discarded");
1218                 goto end;
1219         }
1220         if (discarded < stream->last_discarded_events) {
1221                 /*
1222                  * Overflow has occurred. We assume only one wrap-around
1223                  * has occurred.
1224                  */
1225                 stream->chan->discarded_events += (1ULL << (CAA_BITS_PER_LONG - 1)) -
1226                         stream->last_discarded_events + discarded;
1227         } else {
1228                 stream->chan->discarded_events += discarded -
1229                         stream->last_discarded_events;
1230         }
1231         stream->last_discarded_events = discarded;
1232         ret = 0;
1233
1234 end:
1235         return ret;
1236 }
1237
1238 /*
1239  * Check if the local version of the metadata stream matches with the version
1240  * of the metadata stream in the kernel. If it was updated, set the reset flag
1241  * on the stream.
1242  */
1243 static
1244 int metadata_stream_check_version(int infd, struct lttng_consumer_stream *stream)
1245 {
1246         int ret;
1247         uint64_t cur_version;
1248
1249         ret = kernctl_get_metadata_version(infd, &cur_version);
1250         if (ret < 0) {
1251                 if (ret == -ENOTTY) {
1252                         /*
1253                          * LTTng-modules does not implement this
1254                          * command.
1255                          */
1256                         ret = 0;
1257                         goto end;
1258                 }
1259                 ERR("Failed to get the metadata version");
1260                 goto end;
1261         }
1262
1263         if (stream->metadata_version == cur_version) {
1264                 ret = 0;
1265                 goto end;
1266         }
1267
1268         DBG("New metadata version detected");
1269         stream->metadata_version = cur_version;
1270         stream->reset_metadata_flag = 1;
1271         ret = 0;
1272
1273 end:
1274         return ret;
1275 }
1276
1277 /*
1278  * Consume data on a file descriptor and write it on a trace file.
1279  */
1280 ssize_t lttng_kconsumer_read_subbuffer(struct lttng_consumer_stream *stream,
1281                 struct lttng_consumer_local_data *ctx)
1282 {
1283         unsigned long len, subbuf_size, padding;
1284         int err, write_index = 1;
1285         ssize_t ret = 0;
1286         int infd = stream->wait_fd;
1287         struct ctf_packet_index index;
1288
1289         DBG("In read_subbuffer (infd : %d)", infd);
1290
1291         /* Get the next subbuffer */
1292         err = kernctl_get_next_subbuf(infd);
1293         if (err != 0) {
1294                 /*
1295                  * This is a debug message even for single-threaded consumer,
1296                  * because poll() have more relaxed criterions than get subbuf,
1297                  * so get_subbuf may fail for short race windows where poll()
1298                  * would issue wakeups.
1299                  */
1300                 DBG("Reserving sub buffer failed (everything is normal, "
1301                                 "it is due to concurrency)");
1302                 ret = -errno;
1303                 goto end;
1304         }
1305
1306         /* Get the full subbuffer size including padding */
1307         err = kernctl_get_padded_subbuf_size(infd, &len);
1308         if (err != 0) {
1309                 PERROR("Getting sub-buffer len failed.");
1310                 err = kernctl_put_subbuf(infd);
1311                 if (err != 0) {
1312                         if (errno == EFAULT) {
1313                                 PERROR("Error in unreserving sub buffer\n");
1314                         } else if (errno == EIO) {
1315                                 /* Should never happen with newer LTTng versions */
1316                                 PERROR("Reader has been pushed by the writer, last sub-buffer corrupted.");
1317                         }
1318                         ret = -errno;
1319                         goto end;
1320                 }
1321                 ret = -errno;
1322                 goto end;
1323         }
1324
1325         if (!stream->metadata_flag) {
1326                 ret = get_index_values(&index, infd);
1327                 if (ret < 0) {
1328                         err = kernctl_put_subbuf(infd);
1329                         if (err != 0) {
1330                                 if (errno == EFAULT) {
1331                                         PERROR("Error in unreserving sub buffer\n");
1332                                 } else if (errno == EIO) {
1333                                         /* Should never happen with newer LTTng versions */
1334                                         PERROR("Reader has been pushed by the writer, last sub-buffer corrupted.");
1335                                 }
1336                                 ret = -errno;
1337                                 goto end;
1338                         }
1339                         goto end;
1340                 }
1341                 ret = update_stream_stats(stream);
1342                 if (ret < 0) {
1343                         err = kernctl_put_subbuf(infd);
1344                         if (err != 0) {
1345                                 if (err == -EFAULT) {
1346                                         PERROR("Error in unreserving sub buffer\n");
1347                                 } else if (err == -EIO) {
1348                                         /* Should never happen with newer LTTng versions */
1349                                         PERROR("Reader has been pushed by the writer, last sub-buffer corrupted.");
1350                                 }
1351                                 ret = err;
1352                                 goto end;
1353                         }
1354                         goto end;
1355                 }
1356         } else {
1357                 write_index = 0;
1358                 ret = metadata_stream_check_version(infd, stream);
1359                 if (ret < 0) {
1360                         err = kernctl_put_subbuf(infd);
1361                         if (err != 0) {
1362                                 if (err == -EFAULT) {
1363                                         PERROR("Error in unreserving sub buffer\n");
1364                                 } else if (err == -EIO) {
1365                                         /* Should never happen with newer LTTng versions */
1366                                         PERROR("Reader has been pushed by the writer, last sub-buffer corrupted.");
1367                                 }
1368                                 ret = err;
1369                                 goto end;
1370                         }
1371                         goto end;
1372                 }
1373         }
1374
1375         switch (stream->chan->output) {
1376         case CONSUMER_CHANNEL_SPLICE:
1377                 /*
1378                  * XXX: The lttng-modules splice "actor" does not handle copying
1379                  * partial pages hence only using the subbuffer size without the
1380                  * padding makes the splice fail.
1381                  */
1382                 subbuf_size = len;
1383                 padding = 0;
1384
1385                 /* splice the subbuffer to the tracefile */
1386                 ret = lttng_consumer_on_read_subbuffer_splice(ctx, stream, subbuf_size,
1387                                 padding, &index);
1388                 /*
1389                  * XXX: Splice does not support network streaming so the return value
1390                  * is simply checked against subbuf_size and not like the mmap() op.
1391                  */
1392                 if (ret != subbuf_size) {
1393                         /*
1394                          * display the error but continue processing to try
1395                          * to release the subbuffer
1396                          */
1397                         ERR("Error splicing to tracefile (ret: %zd != len: %lu)",
1398                                         ret, subbuf_size);
1399                         write_index = 0;
1400                 }
1401                 break;
1402         case CONSUMER_CHANNEL_MMAP:
1403                 /* Get subbuffer size without padding */
1404                 err = kernctl_get_subbuf_size(infd, &subbuf_size);
1405                 if (err != 0) {
1406                         PERROR("Getting sub-buffer len failed.");
1407                         err = kernctl_put_subbuf(infd);
1408                         if (err != 0) {
1409                                 if (errno == EFAULT) {
1410                                         PERROR("Error in unreserving sub buffer\n");
1411                                 } else if (errno == EIO) {
1412                                         /* Should never happen with newer LTTng versions */
1413                                         PERROR("Reader has been pushed by the writer, last sub-buffer corrupted.");
1414                                 }
1415                                 ret = -errno;
1416                                 goto end;
1417                         }
1418                         ret = -errno;
1419                         goto end;
1420                 }
1421
1422                 /* Make sure the tracer is not gone mad on us! */
1423                 assert(len >= subbuf_size);
1424
1425                 padding = len - subbuf_size;
1426
1427                 /* write the subbuffer to the tracefile */
1428                 ret = lttng_consumer_on_read_subbuffer_mmap(ctx, stream, subbuf_size,
1429                                 padding, &index);
1430                 /*
1431                  * The mmap operation should write subbuf_size amount of data when
1432                  * network streaming or the full padding (len) size when we are _not_
1433                  * streaming.
1434                  */
1435                 if ((ret != subbuf_size && stream->net_seq_idx != (uint64_t) -1ULL) ||
1436                                 (ret != len && stream->net_seq_idx == (uint64_t) -1ULL)) {
1437                         /*
1438                          * Display the error but continue processing to try to release the
1439                          * subbuffer. This is a DBG statement since this is possible to
1440                          * happen without being a critical error.
1441                          */
1442                         DBG("Error writing to tracefile "
1443                                         "(ret: %zd != len: %lu != subbuf_size: %lu)",
1444                                         ret, len, subbuf_size);
1445                         write_index = 0;
1446                 }
1447                 break;
1448         default:
1449                 ERR("Unknown output method");
1450                 ret = -EPERM;
1451         }
1452
1453         err = kernctl_put_next_subbuf(infd);
1454         if (err != 0) {
1455                 if (errno == EFAULT) {
1456                         PERROR("Error in unreserving sub buffer\n");
1457                 } else if (errno == EIO) {
1458                         /* Should never happen with newer LTTng versions */
1459                         PERROR("Reader has been pushed by the writer, last sub-buffer corrupted.");
1460                 }
1461                 ret = -errno;
1462                 goto end;
1463         }
1464
1465         /* Write index if needed. */
1466         if (!write_index) {
1467                 goto end;
1468         }
1469
1470         if (stream->chan->live_timer_interval && !stream->metadata_flag) {
1471                 /*
1472                  * In live, block until all the metadata is sent.
1473                  */
1474                 pthread_mutex_lock(&stream->metadata_timer_lock);
1475                 assert(!stream->missed_metadata_flush);
1476                 stream->waiting_on_metadata = true;
1477                 pthread_mutex_unlock(&stream->metadata_timer_lock);
1478
1479                 err = consumer_stream_sync_metadata(ctx, stream->session_id);
1480
1481                 pthread_mutex_lock(&stream->metadata_timer_lock);
1482                 stream->waiting_on_metadata = false;
1483                 if (stream->missed_metadata_flush) {
1484                         stream->missed_metadata_flush = false;
1485                         pthread_mutex_unlock(&stream->metadata_timer_lock);
1486                         (void) consumer_flush_kernel_index(stream);
1487                 } else {
1488                         pthread_mutex_unlock(&stream->metadata_timer_lock);
1489                 }
1490                 if (err < 0) {
1491                         goto end;
1492                 }
1493         }
1494
1495         err = consumer_stream_write_index(stream, &index);
1496         if (err < 0) {
1497                 goto end;
1498         }
1499
1500 end:
1501         return ret;
1502 }
1503
1504 int lttng_kconsumer_on_recv_stream(struct lttng_consumer_stream *stream)
1505 {
1506         int ret;
1507
1508         assert(stream);
1509
1510         /*
1511          * Don't create anything if this is set for streaming or should not be
1512          * monitored.
1513          */
1514         if (stream->net_seq_idx == (uint64_t) -1ULL && stream->chan->monitor) {
1515                 ret = utils_create_stream_file(stream->chan->pathname, stream->name,
1516                                 stream->chan->tracefile_size, stream->tracefile_count_current,
1517                                 stream->uid, stream->gid, NULL);
1518                 if (ret < 0) {
1519                         goto error;
1520                 }
1521                 stream->out_fd = ret;
1522                 stream->tracefile_size_current = 0;
1523
1524                 if (!stream->metadata_flag) {
1525                         struct lttng_index_file *index_file;
1526
1527                         index_file = lttng_index_file_create(stream->chan->pathname,
1528                                         stream->name, stream->uid, stream->gid,
1529                                         stream->chan->tracefile_size,
1530                                         stream->tracefile_count_current,
1531                                         CTF_INDEX_MAJOR, CTF_INDEX_MINOR);
1532                         if (!index_file) {
1533                                 goto error;
1534                         }
1535                         stream->index_file = index_file;
1536                 }
1537         }
1538
1539         if (stream->output == LTTNG_EVENT_MMAP) {
1540                 /* get the len of the mmap region */
1541                 unsigned long mmap_len;
1542
1543                 ret = kernctl_get_mmap_len(stream->wait_fd, &mmap_len);
1544                 if (ret != 0) {
1545                         PERROR("kernctl_get_mmap_len");
1546                         ret = -errno;
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 }