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         /*
  64          * -EAGAIN is not an error, it just means that there is no data to
  65          *  be read.
  66          */
  67         if (ret != 0 && ret != -EAGAIN) {
  68                 PERROR("Getting sub-buffer snapshot.");
  69         }
  70
  71         return ret;
  72 }
  73
  74 /*
  75  * Get the produced position
  76  *
  77  * Returns 0 on success, < 0 on error
  78  */
  79 int lttng_kconsumer_get_produced_snapshot(struct lttng_consumer_stream *stream,
  80                 unsigned long *pos)
  81 {
  82         int ret;
  83         int infd = stream->wait_fd;
  84
  85         ret = kernctl_snapshot_get_produced(infd, pos);
  86         if (ret != 0) {
  87                 PERROR("kernctl_snapshot_get_produced");
  88         }
  89
  90         return ret;
  91 }
  92
  93 /*
  94  * Get the consumerd position
  95  *
  96  * Returns 0 on success, < 0 on error
  97  */
  98 int lttng_kconsumer_get_consumed_snapshot(struct lttng_consumer_stream *stream,
  99                 unsigned long *pos)
 100 {
 101         int ret;
 102         int infd = stream->wait_fd;
 103
 104         ret = kernctl_snapshot_get_consumed(infd, pos);
 105         if (ret != 0) {
 106                 PERROR("kernctl_snapshot_get_consumed");
 107         }
 108
 109         return ret;
 110 }
 111
 112 /*
 113  * Take a snapshot of all the stream of a channel
 114  *
 115  * Returns 0 on success, < 0 on error
 116  */
 117 int lttng_kconsumer_snapshot_channel(uint64_t key, char *path,
 118                 uint64_t relayd_id, uint64_t nb_packets_per_stream,
 119                 struct lttng_consumer_local_data *ctx)
 120 {
 121         int ret;
 122         struct lttng_consumer_channel *channel;
 123         struct lttng_consumer_stream *stream;
 124
 125         DBG("Kernel consumer snapshot channel %" PRIu64, key);
 126
 127         rcu_read_lock();
 128
 129         channel = consumer_find_channel(key);
 130         if (!channel) {
 131                 ERR("No channel found for key %" PRIu64, key);
 132                 ret = -1;
 133                 goto end;
 134         }
 135
 136         /* Splice is not supported yet for channel snapshot. */
 137         if (channel->output != CONSUMER_CHANNEL_MMAP) {
 138                 ERR("Unsupported output %d", channel->output);
 139                 ret = -1;
 140                 goto end;
 141         }
 142
 143         cds_list_for_each_entry(stream, &channel->streams.head, send_node) {
 144                 unsigned long consumed_pos, produced_pos;
 145
 146                 health_code_update();
 147
 148                 /*
 149                  * Lock stream because we are about to change its state.
 150                  */
 151                 pthread_mutex_lock(&stream->lock);
 152
 153                 /*
 154                  * Assign the received relayd ID so we can use it for streaming. The streams
 155                  * are not visible to anyone so this is OK to change it.
 156                  */
 157                 stream->net_seq_idx = relayd_id;
 158                 channel->relayd_id = relayd_id;
 159                 if (relayd_id != (uint64_t) -1ULL) {
 160                         ret = consumer_send_relayd_stream(stream, path);
 161                         if (ret < 0) {
 162                                 ERR("sending stream to relayd");
 163                                 goto end_unlock;
 164                         }
 165                 } else {
 166                         ret = utils_create_stream_file(path, stream->name,
 167                                         stream->chan->tracefile_size,
 168                                         stream->tracefile_count_current,
 169                                         stream->uid, stream->gid, NULL);
 170                         if (ret < 0) {
 171                                 ERR("utils_create_stream_file");
 172                                 goto end_unlock;
 173                         }
 174
 175                         stream->out_fd = ret;
 176                         stream->tracefile_size_current = 0;
 177
 178                         DBG("Kernel consumer snapshot stream %s/%s (%" PRIu64 ")",
 179                                         path, stream->name, stream->key);
 180                 }
 181                 if (relayd_id != -1ULL) {
 182                         ret = consumer_send_relayd_streams_sent(relayd_id);
 183                         if (ret < 0) {
 184                                 ERR("sending streams sent to relayd");
 185                                 goto end_unlock;
 186                         }
 187                         channel->streams_sent_to_relayd = true;
 188                 }
 189
 190                 ret = kernctl_buffer_flush_empty(stream->wait_fd);
 191                 if (ret < 0) {
 192                         /*
 193                          * Doing a buffer flush which does not take into
 194                          * account empty packets. This is not perfect
 195                          * for stream intersection, but required as a
 196                          * fall-back when "flush_empty" is not
 197                          * implemented by lttng-modules.
 198                          */
 199                         ret = kernctl_buffer_flush(stream->wait_fd);
 200                         if (ret < 0) {
 201                                 ERR("Failed to flush kernel stream");
 202                                 goto end_unlock;
 203                         }
 204                         goto end_unlock;
 205                 }
 206
 207                 ret = lttng_kconsumer_take_snapshot(stream);
 208                 if (ret < 0) {
 209                         ERR("Taking kernel snapshot");
 210                         goto end_unlock;
 211                 }
 212
 213                 ret = lttng_kconsumer_get_produced_snapshot(stream, &produced_pos);
 214                 if (ret < 0) {
 215                         ERR("Produced kernel snapshot position");
 216                         goto end_unlock;
 217                 }
 218
 219                 ret = lttng_kconsumer_get_consumed_snapshot(stream, &consumed_pos);
 220                 if (ret < 0) {
 221                         ERR("Consumerd kernel snapshot position");
 222                         goto end_unlock;
 223                 }
 224
 225                 if (stream->max_sb_size == 0) {
 226                         ret = kernctl_get_max_subbuf_size(stream->wait_fd,
 227                                         &stream->max_sb_size);
 228                         if (ret < 0) {
 229                                 ERR("Getting kernel max_sb_size");
 230                                 goto end_unlock;
 231                         }
 232                 }
 233
 234                 consumed_pos = consumer_get_consume_start_pos(consumed_pos,
 235                                 produced_pos, nb_packets_per_stream,
 236                                 stream->max_sb_size);
 237
 238                 while (consumed_pos < produced_pos) {
 239                         ssize_t read_len;
 240                         unsigned long len, padded_len;
 241
 242                         health_code_update();
 243
 244                         DBG("Kernel consumer taking snapshot at pos %lu", consumed_pos);
 245
 246                         ret = kernctl_get_subbuf(stream->wait_fd, &consumed_pos);
 247                         if (ret < 0) {
 248                                 if (ret != -EAGAIN) {
 249                                         PERROR("kernctl_get_subbuf snapshot");
 250                                         goto end_unlock;
 251                                 }
 252                                 DBG("Kernel consumer get subbuf failed. Skipping it.");
 253                                 consumed_pos += stream->max_sb_size;
 254                                 stream->chan->lost_packets++;
 255                                 continue;
 256                         }
 257
 258                         ret = kernctl_get_subbuf_size(stream->wait_fd, &len);
 259                         if (ret < 0) {
 260                                 ERR("Snapshot kernctl_get_subbuf_size");
 261                                 goto error_put_subbuf;
 262                         }
 263
 264                         ret = kernctl_get_padded_subbuf_size(stream->wait_fd, &padded_len);
 265                         if (ret < 0) {
 266                                 ERR("Snapshot kernctl_get_padded_subbuf_size");
 267                                 goto error_put_subbuf;
 268                         }
 269
 270                         read_len = lttng_consumer_on_read_subbuffer_mmap(ctx, stream, len,
 271                                         padded_len - len, NULL);
 272                         /*
 273                          * We write the padded len in local tracefiles but the data len
 274                          * when using a relay. Display the error but continue processing
 275                          * to try to release the subbuffer.
 276                          */
 277                         if (relayd_id != (uint64_t) -1ULL) {
 278                                 if (read_len != len) {
 279                                         ERR("Error sending to the relay (ret: %zd != len: %lu)",
 280                                                         read_len, len);
 281                                 }
 282                         } else {
 283                                 if (read_len != padded_len) {
 284                                         ERR("Error writing to tracefile (ret: %zd != len: %lu)",
 285                                                         read_len, padded_len);
 286                                 }
 287                         }
 288
 289                         ret = kernctl_put_subbuf(stream->wait_fd);
 290                         if (ret < 0) {
 291                                 ERR("Snapshot kernctl_put_subbuf");
 292                                 goto end_unlock;
 293                         }
 294                         consumed_pos += stream->max_sb_size;
 295                 }
 296
 297                 if (relayd_id == (uint64_t) -1ULL) {
 298                         if (stream->out_fd >= 0) {
 299                                 ret = close(stream->out_fd);
 300                                 if (ret < 0) {
 301                                         PERROR("Kernel consumer snapshot close out_fd");
 302                                         goto end_unlock;
 303                                 }
 304                                 stream->out_fd = -1;
 305                         }
 306                 } else {
 307                         close_relayd_stream(stream);
 308                         stream->net_seq_idx = (uint64_t) -1ULL;
 309                 }
 310                 pthread_mutex_unlock(&stream->lock);
 311         }
 312
 313         /* All good! */
 314         ret = 0;
 315         goto end;
 316
 317 error_put_subbuf:
 318         ret = kernctl_put_subbuf(stream->wait_fd);
 319         if (ret < 0) {
 320                 ERR("Snapshot kernctl_put_subbuf error path");
 321         }
 322 end_unlock:
 323         pthread_mutex_unlock(&stream->lock);
 324 end:
 325         rcu_read_unlock();
 326         return ret;
 327 }
 328
 329 /*
 330  * Read the whole metadata available for a snapshot.
 331  *
 332  * Returns 0 on success, < 0 on error
 333  */
 334 static int lttng_kconsumer_snapshot_metadata(uint64_t key, char *path,
 335                 uint64_t relayd_id, struct lttng_consumer_local_data *ctx)
 336 {
 337         int ret, use_relayd = 0;
 338         ssize_t ret_read;
 339         struct lttng_consumer_channel *metadata_channel;
 340         struct lttng_consumer_stream *metadata_stream;
 341
 342         assert(ctx);
 343
 344         DBG("Kernel consumer snapshot metadata with key %" PRIu64 " at path %s",
 345                         key, path);
 346
 347         rcu_read_lock();
 348
 349         metadata_channel = consumer_find_channel(key);
 350         if (!metadata_channel) {
 351                 ERR("Kernel snapshot metadata not found for key %" PRIu64, key);
 352                 ret = -1;
 353                 goto error_no_channel;
 354         }
 355
 356         metadata_stream = metadata_channel->metadata_stream;
 357         assert(metadata_stream);
 358         pthread_mutex_lock(&metadata_stream->lock);
 359
 360         /* Flag once that we have a valid relayd for the stream. */
 361         if (relayd_id != (uint64_t) -1ULL) {
 362                 use_relayd = 1;
 363         }
 364
 365         if (use_relayd) {
 366                 ret = consumer_send_relayd_stream(metadata_stream, path);
 367                 if (ret < 0) {
 368                         goto error_snapshot;
 369                 }
 370         } else {
 371                 ret = utils_create_stream_file(path, metadata_stream->name,
 372                                 metadata_stream->chan->tracefile_size,
 373                                 metadata_stream->tracefile_count_current,
 374                                 metadata_stream->uid, metadata_stream->gid, NULL);
 375                 if (ret < 0) {
 376                         goto error_snapshot;
 377                 }
 378                 metadata_stream->out_fd = ret;
 379         }
 380
 381         do {
 382                 health_code_update();
 383
 384                 ret_read = lttng_kconsumer_read_subbuffer(metadata_stream, ctx);
 385                 if (ret_read < 0) {
 386                         if (ret_read != -EAGAIN) {
 387                                 ERR("Kernel snapshot reading metadata subbuffer (ret: %zd)",
 388                                                 ret_read);
 389                                 ret = ret_read;
 390                                 goto error_snapshot;
 391                         }
 392                         /* ret_read is negative at this point so we will exit the loop. */
 393                         continue;
 394                 }
 395         } while (ret_read >= 0);
 396
 397         if (use_relayd) {
 398                 close_relayd_stream(metadata_stream);
 399                 metadata_stream->net_seq_idx = (uint64_t) -1ULL;
 400         } else {
 401                 if (metadata_stream->out_fd >= 0) {
 402                         ret = close(metadata_stream->out_fd);
 403                         if (ret < 0) {
 404                                 PERROR("Kernel consumer snapshot metadata close out_fd");
 405                                 /*
 406                                  * Don't go on error here since the snapshot was successful at this
 407                                  * point but somehow the close failed.
 408                                  */
 409                         }
 410                         metadata_stream->out_fd = -1;
 411                 }
 412         }
 413
 414         ret = 0;
 415 error_snapshot:
 416         pthread_mutex_unlock(&metadata_stream->lock);
 417         cds_list_del(&metadata_stream->send_node);
 418         consumer_stream_destroy(metadata_stream, NULL);
 419         metadata_channel->metadata_stream = NULL;
 420 error_no_channel:
 421         rcu_read_unlock();
 422         return ret;
 423 }
 424
 425 /*
 426  * Receive command from session daemon and process it.
 427  *
 428  * Return 1 on success else a negative value or 0.
 429  */
 430 int lttng_kconsumer_recv_cmd(struct lttng_consumer_local_data *ctx,
 431                 int sock, struct pollfd *consumer_sockpoll)
 432 {
 433         ssize_t ret;
 434         enum lttcomm_return_code ret_code = LTTCOMM_CONSUMERD_SUCCESS;
 435         struct lttcomm_consumer_msg msg;
 436
 437         health_code_update();
 438
 439         ret = lttcomm_recv_unix_sock(sock, &msg, sizeof(msg));
 440         if (ret != sizeof(msg)) {
 441                 if (ret > 0) {
 442                         lttng_consumer_send_error(ctx, LTTCOMM_CONSUMERD_ERROR_RECV_CMD);
 443                         ret = -1;
 444                 }
 445                 return ret;
 446         }
 447
 448         health_code_update();
 449
 450         /* Deprecated command */
 451         assert(msg.cmd_type != LTTNG_CONSUMER_STOP);
 452
 453         health_code_update();
 454
 455         /* relayd needs RCU read-side protection */
 456         rcu_read_lock();
 457
 458         switch (msg.cmd_type) {
 459         case LTTNG_CONSUMER_ADD_RELAYD_SOCKET:
 460         {
 461                 /* Session daemon status message are handled in the following call. */
 462                 ret = consumer_add_relayd_socket(msg.u.relayd_sock.net_index,
 463                                 msg.u.relayd_sock.type, ctx, sock, consumer_sockpoll,
 464                                 &msg.u.relayd_sock.sock, msg.u.relayd_sock.session_id,
 465                                  msg.u.relayd_sock.relayd_session_id);
 466                 goto end_nosignal;
 467         }
 468         case LTTNG_CONSUMER_ADD_CHANNEL:
 469         {
 470                 struct lttng_consumer_channel *new_channel;
 471                 int ret_recv;
 472
 473                 health_code_update();
 474
 475                 /* First send a status message before receiving the fds. */
 476                 ret = consumer_send_status_msg(sock, ret_code);
 477                 if (ret < 0) {
 478                         /* Somehow, the session daemon is not responding anymore. */
 479                         goto error_fatal;
 480                 }
 481
 482                 health_code_update();
 483
 484                 DBG("consumer_add_channel %" PRIu64, msg.u.channel.channel_key);
 485                 new_channel = consumer_allocate_channel(msg.u.channel.channel_key,
 486                                 msg.u.channel.session_id, msg.u.channel.pathname,
 487                                 msg.u.channel.name, msg.u.channel.uid, msg.u.channel.gid,
 488                                 msg.u.channel.relayd_id, msg.u.channel.output,
 489                                 msg.u.channel.tracefile_size,
 490                                 msg.u.channel.tracefile_count, 0,
 491                                 msg.u.channel.monitor,
 492                                 msg.u.channel.live_timer_interval,
 493                                 NULL, NULL);
 494                 if (new_channel == NULL) {
 495                         lttng_consumer_send_error(ctx, LTTCOMM_CONSUMERD_OUTFD_ERROR);
 496                         goto end_nosignal;
 497                 }
 498                 new_channel->nb_init_stream_left = msg.u.channel.nb_init_streams;
 499                 switch (msg.u.channel.output) {
 500                 case LTTNG_EVENT_SPLICE:
 501                         new_channel->output = CONSUMER_CHANNEL_SPLICE;
 502                         break;
 503                 case LTTNG_EVENT_MMAP:
 504                         new_channel->output = CONSUMER_CHANNEL_MMAP;
 505                         break;
 506                 default:
 507                         ERR("Channel output unknown %d", msg.u.channel.output);
 508                         goto end_nosignal;
 509                 }
 510
 511                 /* Translate and save channel type. */
 512                 switch (msg.u.channel.type) {
 513                 case CONSUMER_CHANNEL_TYPE_DATA:
 514                 case CONSUMER_CHANNEL_TYPE_METADATA:
 515                         new_channel->type = msg.u.channel.type;
 516                         break;
 517                 default:
 518                         assert(0);
 519                         goto end_nosignal;
 520                 };
 521
 522                 health_code_update();
 523
 524                 if (ctx->on_recv_channel != NULL) {
 525                         ret_recv = ctx->on_recv_channel(new_channel);
 526                         if (ret_recv == 0) {
 527                                 ret = consumer_add_channel(new_channel, ctx);
 528                         } else if (ret_recv < 0) {
 529                                 goto end_nosignal;
 530                         }
 531                 } else {
 532                         ret = consumer_add_channel(new_channel, ctx);
 533                 }
 534                 if (CONSUMER_CHANNEL_TYPE_DATA) {
 535                         consumer_timer_live_start(new_channel,
 536                                         msg.u.channel.live_timer_interval);
 537                 }
 538
 539                 health_code_update();
 540
 541                 /* If we received an error in add_channel, we need to report it. */
 542                 if (ret < 0) {
 543                         ret = consumer_send_status_msg(sock, ret);
 544                         if (ret < 0) {
 545                                 goto error_fatal;
 546                         }
 547                         goto end_nosignal;
 548                 }
 549
 550                 goto end_nosignal;
 551         }
 552         case LTTNG_CONSUMER_ADD_STREAM:
 553         {
 554                 int fd;
 555                 struct lttng_pipe *stream_pipe;
 556                 struct lttng_consumer_stream *new_stream;
 557                 struct lttng_consumer_channel *channel;
 558                 int alloc_ret = 0;
 559
 560                 /*
 561                  * Get stream's channel reference. Needed when adding the stream to the
 562                  * global hash table.
 563                  */
 564                 channel = consumer_find_channel(msg.u.stream.channel_key);
 565                 if (!channel) {
 566                         /*
 567                          * We could not find the channel. Can happen if cpu hotplug
 568                          * happens while tearing down.
 569                          */
 570                         ERR("Unable to find channel key %" PRIu64, msg.u.stream.channel_key);
 571                         ret_code = LTTCOMM_CONSUMERD_CHAN_NOT_FOUND;
 572                 }
 573
 574                 health_code_update();
 575
 576                 /* First send a status message before receiving the fds. */
 577                 ret = consumer_send_status_msg(sock, ret_code);
 578                 if (ret < 0) {
 579                         /* Somehow, the session daemon is not responding anymore. */
 580                         goto error_fatal;
 581                 }
 582
 583                 health_code_update();
 584
 585                 if (ret_code != LTTCOMM_CONSUMERD_SUCCESS) {
 586                         /* Channel was not found. */
 587                         goto end_nosignal;
 588                 }
 589
 590                 /* Blocking call */
 591                 health_poll_entry();
 592                 ret = lttng_consumer_poll_socket(consumer_sockpoll);
 593                 health_poll_exit();
 594                 if (ret) {
 595                         goto error_fatal;
 596                 }
 597
 598                 health_code_update();
 599
 600                 /* Get stream file descriptor from socket */
 601                 ret = lttcomm_recv_fds_unix_sock(sock, &fd, 1);
 602                 if (ret != sizeof(fd)) {
 603                         lttng_consumer_send_error(ctx, LTTCOMM_CONSUMERD_ERROR_RECV_FD);
 604                         rcu_read_unlock();
 605                         return ret;
 606                 }
 607
 608                 health_code_update();
 609
 610                 /*
 611                  * Send status code to session daemon only if the recv works. If the
 612                  * above recv() failed, the session daemon is notified through the
 613                  * error socket and the teardown is eventually done.
 614                  */
 615                 ret = consumer_send_status_msg(sock, ret_code);
 616                 if (ret < 0) {
 617                         /* Somehow, the session daemon is not responding anymore. */
 618                         goto end_nosignal;
 619                 }
 620
 621                 health_code_update();
 622
 623                 new_stream = consumer_allocate_stream(channel->key,
 624                                 fd,
 625                                 LTTNG_CONSUMER_ACTIVE_STREAM,
 626                                 channel->name,
 627                                 channel->uid,
 628                                 channel->gid,
 629                                 channel->relayd_id,
 630                                 channel->session_id,
 631                                 msg.u.stream.cpu,
 632                                 &alloc_ret,
 633                                 channel->type,
 634                                 channel->monitor);
 635                 if (new_stream == NULL) {
 636                         switch (alloc_ret) {
 637                         case -ENOMEM:
 638                         case -EINVAL:
 639                         default:
 640                                 lttng_consumer_send_error(ctx, LTTCOMM_CONSUMERD_OUTFD_ERROR);
 641                                 break;
 642                         }
 643                         goto end_nosignal;
 644                 }
 645
 646                 new_stream->chan = channel;
 647                 new_stream->wait_fd = fd;
 648                 switch (channel->output) {
 649                 case CONSUMER_CHANNEL_SPLICE:
 650                         new_stream->output = LTTNG_EVENT_SPLICE;
 651                         ret = utils_create_pipe(new_stream->splice_pipe);
 652                         if (ret < 0) {
 653                                 goto end_nosignal;
 654                         }
 655                         break;
 656                 case CONSUMER_CHANNEL_MMAP:
 657                         new_stream->output = LTTNG_EVENT_MMAP;
 658                         break;
 659                 default:
 660                         ERR("Stream output unknown %d", channel->output);
 661                         goto end_nosignal;
 662                 }
 663
 664                 /*
 665                  * We've just assigned the channel to the stream so increment the
 666                  * refcount right now. We don't need to increment the refcount for
 667                  * streams in no monitor because we handle manually the cleanup of
 668                  * those. It is very important to make sure there is NO prior
 669                  * consumer_del_stream() calls or else the refcount will be unbalanced.
 670                  */
 671                 if (channel->monitor) {
 672                         uatomic_inc(&new_stream->chan->refcount);
 673                 }
 674
 675                 /*
 676                  * The buffer flush is done on the session daemon side for the kernel
 677                  * so no need for the stream "hangup_flush_done" variable to be
 678                  * tracked. This is important for a kernel stream since we don't rely
 679                  * on the flush state of the stream to read data. It's not the case for
 680                  * user space tracing.
 681                  */
 682                 new_stream->hangup_flush_done = 0;
 683
 684                 health_code_update();
 685
 686                 if (ctx->on_recv_stream) {
 687                         ret = ctx->on_recv_stream(new_stream);
 688                         if (ret < 0) {
 689                                 consumer_stream_free(new_stream);
 690                                 goto end_nosignal;
 691                         }
 692                 }
 693
 694                 health_code_update();
 695
 696                 if (new_stream->metadata_flag) {
 697                         channel->metadata_stream = new_stream;
 698                 }
 699
 700                 /* Do not monitor this stream. */
 701                 if (!channel->monitor) {
 702                         DBG("Kernel consumer add stream %s in no monitor mode with "
 703                                         "relayd id %" PRIu64, new_stream->name,
 704                                         new_stream->net_seq_idx);
 705                         cds_list_add(&new_stream->send_node, &channel->streams.head);
 706                         break;
 707                 }
 708
 709                 /* Send stream to relayd if the stream has an ID. */
 710                 if (new_stream->net_seq_idx != (uint64_t) -1ULL) {
 711                         ret = consumer_send_relayd_stream(new_stream,
 712                                         new_stream->chan->pathname);
 713                         if (ret < 0) {
 714                                 consumer_stream_free(new_stream);
 715                                 goto end_nosignal;
 716                         }
 717
 718                         /*
 719                          * If adding an extra stream to an already
 720                          * existing channel (e.g. cpu hotplug), we need
 721                          * to send the "streams_sent" command to relayd.
 722                          */
 723                         if (channel->streams_sent_to_relayd) {
 724                                 ret = consumer_send_relayd_streams_sent(
 725                                                 new_stream->net_seq_idx);
 726                                 if (ret < 0) {
 727                                         goto end_nosignal;
 728                                 }
 729                         }
 730                 }
 731
 732                 /* Get the right pipe where the stream will be sent. */
 733                 if (new_stream->metadata_flag) {
 734                         ret = consumer_add_metadata_stream(new_stream);
 735                         if (ret) {
 736                                 ERR("Consumer add metadata stream %" PRIu64 " failed. Continuing",
 737                                                 new_stream->key);
 738                                 consumer_stream_free(new_stream);
 739                                 goto end_nosignal;
 740                         }
 741                         stream_pipe = ctx->consumer_metadata_pipe;
 742                 } else {
 743                         ret = consumer_add_data_stream(new_stream);
 744                         if (ret) {
 745                                 ERR("Consumer add stream %" PRIu64 " failed. Continuing",
 746                                                 new_stream->key);
 747                                 consumer_stream_free(new_stream);
 748                                 goto end_nosignal;
 749                         }
 750                         stream_pipe = ctx->consumer_data_pipe;
 751                 }
 752
 753                 /* Vitible to other threads */
 754                 new_stream->globally_visible = 1;
 755
 756                 health_code_update();
 757
 758                 ret = lttng_pipe_write(stream_pipe, &new_stream, sizeof(new_stream));
 759                 if (ret < 0) {
 760                         ERR("Consumer write %s stream to pipe %d",
 761                                         new_stream->metadata_flag ? "metadata" : "data",
 762                                         lttng_pipe_get_writefd(stream_pipe));
 763                         if (new_stream->metadata_flag) {
 764                                 consumer_del_stream_for_metadata(new_stream);
 765                         } else {
 766                                 consumer_del_stream_for_data(new_stream);
 767                         }
 768                         goto end_nosignal;
 769                 }
 770
 771                 DBG("Kernel consumer ADD_STREAM %s (fd: %d) with relayd id %" PRIu64,
 772                                 new_stream->name, fd, new_stream->relayd_stream_id);
 773                 break;
 774         }
 775         case LTTNG_CONSUMER_STREAMS_SENT:
 776         {
 777                 struct lttng_consumer_channel *channel;
 778
 779                 /*
 780                  * Get stream's channel reference. Needed when adding the stream to the
 781                  * global hash table.
 782                  */
 783                 channel = consumer_find_channel(msg.u.sent_streams.channel_key);
 784                 if (!channel) {
 785                         /*
 786                          * We could not find the channel. Can happen if cpu hotplug
 787                          * happens while tearing down.
 788                          */
 789                         ERR("Unable to find channel key %" PRIu64,
 790                                         msg.u.sent_streams.channel_key);
 791                         ret_code = LTTCOMM_CONSUMERD_CHAN_NOT_FOUND;
 792                 }
 793
 794                 health_code_update();
 795
 796                 /*
 797                  * Send status code to session daemon.
 798                  */
 799                 ret = consumer_send_status_msg(sock, ret_code);
 800                 if (ret < 0 || ret_code != LTTCOMM_CONSUMERD_SUCCESS) {
 801                         /* Somehow, the session daemon is not responding anymore. */
 802                         goto end_nosignal;
 803                 }
 804
 805                 health_code_update();
 806
 807                 /*
 808                  * We should not send this message if we don't monitor the
 809                  * streams in this channel.
 810                  */
 811                 if (!channel->monitor) {
 812                         break;
 813                 }
 814
 815                 health_code_update();
 816                 /* Send stream to relayd if the stream has an ID. */
 817                 if (msg.u.sent_streams.net_seq_idx != (uint64_t) -1ULL) {
 818                         ret = consumer_send_relayd_streams_sent(
 819                                         msg.u.sent_streams.net_seq_idx);
 820                         if (ret < 0) {
 821                                 goto end_nosignal;
 822                         }
 823                         channel->streams_sent_to_relayd = true;
 824                 }
 825                 break;
 826         }
 827         case LTTNG_CONSUMER_UPDATE_STREAM:
 828         {
 829                 rcu_read_unlock();
 830                 return -ENOSYS;
 831         }
 832         case LTTNG_CONSUMER_DESTROY_RELAYD:
 833         {
 834                 uint64_t index = msg.u.destroy_relayd.net_seq_idx;
 835                 struct consumer_relayd_sock_pair *relayd;
 836
 837                 DBG("Kernel consumer destroying relayd %" PRIu64, index);
 838
 839                 /* Get relayd reference if exists. */
 840                 relayd = consumer_find_relayd(index);
 841                 if (relayd == NULL) {
 842                         DBG("Unable to find relayd %" PRIu64, index);
 843                         ret_code = LTTCOMM_CONSUMERD_RELAYD_FAIL;
 844                 }
 845
 846                 /*
 847                  * Each relayd socket pair has a refcount of stream attached to it
 848                  * which tells if the relayd is still active or not depending on the
 849                  * refcount value.
 850                  *
 851                  * This will set the destroy flag of the relayd object and destroy it
 852                  * if the refcount reaches zero when called.
 853                  *
 854                  * The destroy can happen either here or when a stream fd hangs up.
 855                  */
 856                 if (relayd) {
 857                         consumer_flag_relayd_for_destroy(relayd);
 858                 }
 859
 860                 health_code_update();
 861
 862                 ret = consumer_send_status_msg(sock, ret_code);
 863                 if (ret < 0) {
 864                         /* Somehow, the session daemon is not responding anymore. */
 865                         goto error_fatal;
 866                 }
 867
 868                 goto end_nosignal;
 869         }
 870         case LTTNG_CONSUMER_DATA_PENDING:
 871         {
 872                 int32_t ret;
 873                 uint64_t id = msg.u.data_pending.session_id;
 874
 875                 DBG("Kernel consumer data pending command for id %" PRIu64, id);
 876
 877                 ret = consumer_data_pending(id);
 878
 879                 health_code_update();
 880
 881                 /* Send back returned value to session daemon */
 882                 ret = lttcomm_send_unix_sock(sock, &ret, sizeof(ret));
 883                 if (ret < 0) {
 884                         PERROR("send data pending ret code");
 885                         goto error_fatal;
 886                 }
 887
 888                 /*
 889                  * No need to send back a status message since the data pending
 890                  * returned value is the response.
 891                  */
 892                 break;
 893         }
 894         case LTTNG_CONSUMER_SNAPSHOT_CHANNEL:
 895         {
 896                 if (msg.u.snapshot_channel.metadata == 1) {
 897                         ret = lttng_kconsumer_snapshot_metadata(msg.u.snapshot_channel.key,
 898                                         msg.u.snapshot_channel.pathname,
 899                                         msg.u.snapshot_channel.relayd_id, ctx);
 900                         if (ret < 0) {
 901                                 ERR("Snapshot metadata failed");
 902                                 ret_code = LTTCOMM_CONSUMERD_ERROR_METADATA;
 903                         }
 904                 } else {
 905                         ret = lttng_kconsumer_snapshot_channel(msg.u.snapshot_channel.key,
 906                                         msg.u.snapshot_channel.pathname,
 907                                         msg.u.snapshot_channel.relayd_id,
 908                                         msg.u.snapshot_channel.nb_packets_per_stream,
 909                                         ctx);
 910                         if (ret < 0) {
 911                                 ERR("Snapshot channel failed");
 912                                 ret_code = LTTCOMM_CONSUMERD_CHAN_NOT_FOUND;
 913                         }
 914                 }
 915
 916                 health_code_update();
 917
 918                 ret = consumer_send_status_msg(sock, ret_code);
 919                 if (ret < 0) {
 920                         /* Somehow, the session daemon is not responding anymore. */
 921                         goto end_nosignal;
 922                 }
 923                 break;
 924         }
 925         case LTTNG_CONSUMER_DESTROY_CHANNEL:
 926         {
 927                 uint64_t key = msg.u.destroy_channel.key;
 928                 struct lttng_consumer_channel *channel;
 929
 930                 channel = consumer_find_channel(key);
 931                 if (!channel) {
 932                         ERR("Kernel consumer destroy channel %" PRIu64 " not found", key);
 933                         ret_code = LTTCOMM_CONSUMERD_CHAN_NOT_FOUND;
 934                 }
 935
 936                 health_code_update();
 937
 938                 ret = consumer_send_status_msg(sock, ret_code);
 939                 if (ret < 0) {
 940                         /* Somehow, the session daemon is not responding anymore. */
 941                         goto end_nosignal;
 942                 }
 943
 944                 health_code_update();
 945
 946                 /* Stop right now if no channel was found. */
 947                 if (!channel) {
 948                         goto end_nosignal;
 949                 }
 950
 951                 /*
 952                  * This command should ONLY be issued for channel with streams set in
 953                  * no monitor mode.
 954                  */
 955                 assert(!channel->monitor);
 956
 957                 /*
 958                  * The refcount should ALWAYS be 0 in the case of a channel in no
 959                  * monitor mode.
 960                  */
 961                 assert(!uatomic_sub_return(&channel->refcount, 1));
 962
 963                 consumer_del_channel(channel);
 964
 965                 goto end_nosignal;
 966         }
 967         case LTTNG_CONSUMER_DISCARDED_EVENTS:
 968         {
 969                 uint64_t ret;
 970                 struct lttng_consumer_channel *channel;
 971                 uint64_t id = msg.u.discarded_events.session_id;
 972                 uint64_t key = msg.u.discarded_events.channel_key;
 973
 974                 DBG("Kernel consumer discarded events command for session id %"
 975                                 PRIu64 ", channel key %" PRIu64, id, key);
 976
 977                 channel = consumer_find_channel(key);
 978                 if (!channel) {
 979                         ERR("Kernel consumer discarded events channel %"
 980                                         PRIu64 " not found", key);
 981                         ret = 0;
 982                 } else {
 983                         ret = channel->discarded_events;
 984                 }
 985
 986                 health_code_update();
 987
 988                 /* Send back returned value to session daemon */
 989                 ret = lttcomm_send_unix_sock(sock, &ret, sizeof(ret));
 990                 if (ret < 0) {
 991                         PERROR("send discarded events");
 992                         goto error_fatal;
 993                 }
 994
 995                 break;
 996         }
 997         case LTTNG_CONSUMER_LOST_PACKETS:
 998         {
 999                 uint64_t ret;
1000                 struct lttng_consumer_channel *channel;
1001                 uint64_t id = msg.u.lost_packets.session_id;
1002                 uint64_t key = msg.u.lost_packets.channel_key;
1003
1004                 DBG("Kernel consumer lost packets command for session id %"
1005                                 PRIu64 ", channel key %" PRIu64, id, key);
1006
1007                 channel = consumer_find_channel(key);
1008                 if (!channel) {
1009                         ERR("Kernel consumer lost packets channel %"
1010                                         PRIu64 " not found", key);
1011                         ret = 0;
1012                 } else {
1013                         ret = channel->lost_packets;
1014                 }
1015
1016                 health_code_update();
1017
1018                 /* Send back returned value to session daemon */
1019                 ret = lttcomm_send_unix_sock(sock, &ret, sizeof(ret));
1020                 if (ret < 0) {
1021                         PERROR("send lost packets");
1022                         goto error_fatal;
1023                 }
1024
1025                 break;
1026         }
1027         default:
1028                 goto end_nosignal;
1029         }
1030
1031 end_nosignal:
1032         rcu_read_unlock();
1033
1034         /*
1035          * Return 1 to indicate success since the 0 value can be a socket
1036          * shutdown during the recv() or send() call.
1037          */
1038         health_code_update();
1039         return 1;
1040
1041 error_fatal:
1042         rcu_read_unlock();
1043         /* This will issue a consumer stop. */
1044         return -1;
1045 }
1046
1047 /*
1048  * Populate index values of a kernel stream. Values are set in big endian order.
1049  *
1050  * Return 0 on success or else a negative value.
1051  */
1052 static int get_index_values(struct ctf_packet_index *index, int infd)
1053 {
1054         int ret;
1055
1056         ret = kernctl_get_timestamp_begin(infd, &index->timestamp_begin);
1057         if (ret < 0) {
1058                 PERROR("kernctl_get_timestamp_begin");
1059                 goto error;
1060         }
1061         index->timestamp_begin = htobe64(index->timestamp_begin);
1062
1063         ret = kernctl_get_timestamp_end(infd, &index->timestamp_end);
1064         if (ret < 0) {
1065                 PERROR("kernctl_get_timestamp_end");
1066                 goto error;
1067         }
1068         index->timestamp_end = htobe64(index->timestamp_end);
1069
1070         ret = kernctl_get_events_discarded(infd, &index->events_discarded);
1071         if (ret < 0) {
1072                 PERROR("kernctl_get_events_discarded");
1073                 goto error;
1074         }
1075         index->events_discarded = htobe64(index->events_discarded);
1076
1077         ret = kernctl_get_content_size(infd, &index->content_size);
1078         if (ret < 0) {
1079                 PERROR("kernctl_get_content_size");
1080                 goto error;
1081         }
1082         index->content_size = htobe64(index->content_size);
1083
1084         ret = kernctl_get_packet_size(infd, &index->packet_size);
1085         if (ret < 0) {
1086                 PERROR("kernctl_get_packet_size");
1087                 goto error;
1088         }
1089         index->packet_size = htobe64(index->packet_size);
1090
1091         ret = kernctl_get_stream_id(infd, &index->stream_id);
1092         if (ret < 0) {
1093                 PERROR("kernctl_get_stream_id");
1094                 goto error;
1095         }
1096         index->stream_id = htobe64(index->stream_id);
1097
1098         ret = kernctl_get_instance_id(infd, &index->stream_instance_id);
1099         if (ret < 0) {
1100                 if (ret == -ENOTTY) {
1101                         /* Command not implemented by lttng-modules. */
1102                         index->stream_instance_id = -1ULL;
1103                         ret = 0;
1104                 } else {
1105                         PERROR("kernctl_get_instance_id");
1106                         goto error;
1107                 }
1108         }
1109         index->stream_instance_id = htobe64(index->stream_instance_id);
1110
1111         ret = kernctl_get_sequence_number(infd, &index->packet_seq_num);
1112         if (ret < 0) {
1113                 if (ret == -ENOTTY) {
1114                         /* Command not implemented by lttng-modules. */
1115                         index->packet_seq_num = -1ULL;
1116                         ret = 0;
1117                 } else {
1118                         PERROR("kernctl_get_sequence_number");
1119                         goto error;
1120                 }
1121         }
1122         index->packet_seq_num = htobe64(index->packet_seq_num);
1123
1124 error:
1125         return ret;
1126 }
1127 /*
1128  * Sync metadata meaning request them to the session daemon and snapshot to the
1129  * metadata thread can consumer them.
1130  *
1131  * Metadata stream lock MUST be acquired.
1132  *
1133  * Return 0 if new metadatda is available, EAGAIN if the metadata stream
1134  * is empty or a negative value on error.
1135  */
1136 int lttng_kconsumer_sync_metadata(struct lttng_consumer_stream *metadata)
1137 {
1138         int ret;
1139
1140         assert(metadata);
1141
1142         ret = kernctl_buffer_flush(metadata->wait_fd);
1143         if (ret < 0) {
1144                 ERR("Failed to flush kernel stream");
1145                 goto end;
1146         }
1147
1148         ret = kernctl_snapshot(metadata->wait_fd);
1149         if (ret < 0) {
1150                 if (ret != -EAGAIN) {
1151                         ERR("Sync metadata, taking kernel snapshot failed.");
1152                         goto end;
1153                 }
1154                 DBG("Sync metadata, no new kernel metadata");
1155                 /* No new metadata, exit. */
1156                 ret = ENODATA;
1157                 goto end;
1158         }
1159
1160 end:
1161         return ret;
1162 }
1163
1164 static
1165 int update_stream_stats(struct lttng_consumer_stream *stream)
1166 {
1167         int ret;
1168         uint64_t seq, discarded;
1169
1170         ret = kernctl_get_sequence_number(stream->wait_fd, &seq);
1171         if (ret < 0) {
1172                 if (ret == -ENOTTY) {
1173                         /* Command not implemented by lttng-modules. */
1174                         seq = -1ULL;
1175                         ret = 0;
1176                 } else {
1177                         PERROR("kernctl_get_sequence_number");
1178                         goto end;
1179                 }
1180         }
1181
1182         /*
1183          * Start the sequence when we extract the first packet in case we don't
1184          * start at 0 (for example if a consumer is not connected to the
1185          * session immediately after the beginning).
1186          */
1187         if (stream->last_sequence_number == -1ULL) {
1188                 stream->last_sequence_number = seq;
1189         } else if (seq > stream->last_sequence_number) {
1190                 stream->chan->lost_packets += seq -
1191                                 stream->last_sequence_number - 1;
1192         } else {
1193                 /* seq <= last_sequence_number */
1194                 ERR("Sequence number inconsistent : prev = %" PRIu64
1195                                 ", current = %" PRIu64,
1196                                 stream->last_sequence_number, seq);
1197                 ret = -1;
1198                 goto end;
1199         }
1200         stream->last_sequence_number = seq;
1201
1202         ret = kernctl_get_events_discarded(stream->wait_fd, &discarded);
1203         if (ret < 0) {
1204                 PERROR("kernctl_get_events_discarded");
1205                 goto end;
1206         }
1207         if (discarded < stream->last_discarded_events) {
1208                 /*
1209                  * Overflow has occurred. We assume only one wrap-around
1210                  * has occurred.
1211                  */
1212                 stream->chan->discarded_events += (1ULL << (CAA_BITS_PER_LONG - 1)) -
1213                         stream->last_discarded_events + discarded;
1214         } else {
1215                 stream->chan->discarded_events += discarded -
1216                         stream->last_discarded_events;
1217         }
1218         stream->last_discarded_events = discarded;
1219         ret = 0;
1220
1221 end:
1222         return ret;
1223 }
1224
1225 /*
1226  * Check if the local version of the metadata stream matches with the version
1227  * of the metadata stream in the kernel. If it was updated, set the reset flag
1228  * on the stream.
1229  */
1230 static
1231 int metadata_stream_check_version(int infd, struct lttng_consumer_stream *stream)
1232 {
1233         int ret;
1234         uint64_t cur_version;
1235
1236         ret = kernctl_get_metadata_version(infd, &cur_version);
1237         if (ret < 0) {
1238                 if (ret == -ENOTTY) {
1239                         /*
1240                          * LTTng-modules does not implement this
1241                          * command.
1242                          */
1243                         ret = 0;
1244                         goto end;
1245                 }
1246                 ERR("Failed to get the metadata version");
1247                 goto end;
1248         }
1249
1250         if (stream->metadata_version == cur_version) {
1251                 ret = 0;
1252                 goto end;
1253         }
1254
1255         DBG("New metadata version detected");
1256         stream->metadata_version = cur_version;
1257         stream->reset_metadata_flag = 1;
1258         ret = 0;
1259
1260 end:
1261         return ret;
1262 }
1263
1264 /*
1265  * Consume data on a file descriptor and write it on a trace file.
1266  */
1267 ssize_t lttng_kconsumer_read_subbuffer(struct lttng_consumer_stream *stream,
1268                 struct lttng_consumer_local_data *ctx)
1269 {
1270         unsigned long len, subbuf_size, padding;
1271         int err, write_index = 1;
1272         ssize_t ret = 0;
1273         int infd = stream->wait_fd;
1274         struct ctf_packet_index index;
1275
1276         DBG("In read_subbuffer (infd : %d)", infd);
1277
1278         /* Get the next subbuffer */
1279         err = kernctl_get_next_subbuf(infd);
1280         if (err != 0) {
1281                 /*
1282                  * This is a debug message even for single-threaded consumer,
1283                  * because poll() have more relaxed criterions than get subbuf,
1284                  * so get_subbuf may fail for short race windows where poll()
1285                  * would issue wakeups.
1286                  */
1287                 DBG("Reserving sub buffer failed (everything is normal, "
1288                                 "it is due to concurrency)");
1289                 ret = err;
1290                 goto end;
1291         }
1292
1293         /* Get the full subbuffer size including padding */
1294         err = kernctl_get_padded_subbuf_size(infd, &len);
1295         if (err != 0) {
1296                 PERROR("Getting sub-buffer len failed.");
1297                 err = kernctl_put_subbuf(infd);
1298                 if (err != 0) {
1299                         if (err == -EFAULT) {
1300                                 PERROR("Error in unreserving sub buffer\n");
1301                         } else if (err == -EIO) {
1302                                 /* Should never happen with newer LTTng versions */
1303                                 PERROR("Reader has been pushed by the writer, last sub-buffer corrupted.");
1304                         }
1305                         ret = err;
1306                         goto end;
1307                 }
1308                 ret = err;
1309                 goto end;
1310         }
1311
1312         if (!stream->metadata_flag) {
1313                 ret = get_index_values(&index, infd);
1314                 if (ret < 0) {
1315                         err = kernctl_put_subbuf(infd);
1316                         if (err != 0) {
1317                                 if (err == -EFAULT) {
1318                                         PERROR("Error in unreserving sub buffer\n");
1319                                 } else if (err == -EIO) {
1320                                         /* Should never happen with newer LTTng versions */
1321                                         PERROR("Reader has been pushed by the writer, last sub-buffer corrupted.");
1322                                 }
1323                                 ret = err;
1324                                 goto end;
1325                         }
1326                         goto end;
1327                 }
1328                 ret = update_stream_stats(stream);
1329                 if (ret < 0) {
1330                         err = kernctl_put_subbuf(infd);
1331                         if (err != 0) {
1332                                 if (err == -EFAULT) {
1333                                         PERROR("Error in unreserving sub buffer\n");
1334                                 } else if (err == -EIO) {
1335                                         /* Should never happen with newer LTTng versions */
1336                                         PERROR("Reader has been pushed by the writer, last sub-buffer corrupted.");
1337                                 }
1338                                 ret = err;
1339                                 goto end;
1340                         }
1341                         goto end;
1342                 }
1343         } else {
1344                 write_index = 0;
1345                 ret = metadata_stream_check_version(infd, stream);
1346                 if (ret < 0) {
1347                         err = kernctl_put_subbuf(infd);
1348                         if (err != 0) {
1349                                 if (err == -EFAULT) {
1350                                         PERROR("Error in unreserving sub buffer\n");
1351                                 } else if (err == -EIO) {
1352                                         /* Should never happen with newer LTTng versions */
1353                                         PERROR("Reader has been pushed by the writer, last sub-buffer corrupted.");
1354                                 }
1355                                 ret = err;
1356                                 goto end;
1357                         }
1358                         goto end;
1359                 }
1360         }
1361
1362         switch (stream->chan->output) {
1363         case CONSUMER_CHANNEL_SPLICE:
1364                 /*
1365                  * XXX: The lttng-modules splice "actor" does not handle copying
1366                  * partial pages hence only using the subbuffer size without the
1367                  * padding makes the splice fail.
1368                  */
1369                 subbuf_size = len;
1370                 padding = 0;
1371
1372                 /* splice the subbuffer to the tracefile */
1373                 ret = lttng_consumer_on_read_subbuffer_splice(ctx, stream, subbuf_size,
1374                                 padding, &index);
1375                 /*
1376                  * XXX: Splice does not support network streaming so the return value
1377                  * is simply checked against subbuf_size and not like the mmap() op.
1378                  */
1379                 if (ret != subbuf_size) {
1380                         /*
1381                          * display the error but continue processing to try
1382                          * to release the subbuffer
1383                          */
1384                         ERR("Error splicing to tracefile (ret: %zd != len: %lu)",
1385                                         ret, subbuf_size);
1386                         write_index = 0;
1387                 }
1388                 break;
1389         case CONSUMER_CHANNEL_MMAP:
1390                 /* Get subbuffer size without padding */
1391                 err = kernctl_get_subbuf_size(infd, &subbuf_size);
1392                 if (err != 0) {
1393                         PERROR("Getting sub-buffer len failed.");
1394                         err = kernctl_put_subbuf(infd);
1395                         if (err != 0) {
1396                                 if (err == -EFAULT) {
1397                                         PERROR("Error in unreserving sub buffer\n");
1398                                 } else if (err == -EIO) {
1399                                         /* Should never happen with newer LTTng versions */
1400                                         PERROR("Reader has been pushed by the writer, last sub-buffer corrupted.");
1401                                 }
1402                                 ret = err;
1403                                 goto end;
1404                         }
1405                         ret = err;
1406                         goto end;
1407                 }
1408
1409                 /* Make sure the tracer is not gone mad on us! */
1410                 assert(len >= subbuf_size);
1411
1412                 padding = len - subbuf_size;
1413
1414                 /* write the subbuffer to the tracefile */
1415                 ret = lttng_consumer_on_read_subbuffer_mmap(ctx, stream, subbuf_size,
1416                                 padding, &index);
1417                 /*
1418                  * The mmap operation should write subbuf_size amount of data when
1419                  * network streaming or the full padding (len) size when we are _not_
1420                  * streaming.
1421                  */
1422                 if ((ret != subbuf_size && stream->net_seq_idx != (uint64_t) -1ULL) ||
1423                                 (ret != len && stream->net_seq_idx == (uint64_t) -1ULL)) {
1424                         /*
1425                          * Display the error but continue processing to try to release the
1426                          * subbuffer. This is a DBG statement since this is possible to
1427                          * happen without being a critical error.
1428                          */
1429                         DBG("Error writing to tracefile "
1430                                         "(ret: %zd != len: %lu != subbuf_size: %lu)",
1431                                         ret, len, subbuf_size);
1432                         write_index = 0;
1433                 }
1434                 break;
1435         default:
1436                 ERR("Unknown output method");
1437                 ret = -EPERM;
1438         }
1439
1440         err = kernctl_put_next_subbuf(infd);
1441         if (err != 0) {
1442                 if (err == -EFAULT) {
1443                         PERROR("Error in unreserving sub buffer\n");
1444                 } else if (err == -EIO) {
1445                         /* Should never happen with newer LTTng versions */
1446                         PERROR("Reader has been pushed by the writer, last sub-buffer corrupted.");
1447                 }
1448                 ret = err;
1449                 goto end;
1450         }
1451
1452         /* Write index if needed. */
1453         if (!write_index) {
1454                 goto end;
1455         }
1456
1457         if (stream->chan->live_timer_interval && !stream->metadata_flag) {
1458                 /*
1459                  * In live, block until all the metadata is sent.
1460                  */
1461                 pthread_mutex_lock(&stream->metadata_timer_lock);
1462                 assert(!stream->missed_metadata_flush);
1463                 stream->waiting_on_metadata = true;
1464                 pthread_mutex_unlock(&stream->metadata_timer_lock);
1465
1466                 err = consumer_stream_sync_metadata(ctx, stream->session_id);
1467
1468                 pthread_mutex_lock(&stream->metadata_timer_lock);
1469                 stream->waiting_on_metadata = false;
1470                 if (stream->missed_metadata_flush) {
1471                         stream->missed_metadata_flush = false;
1472                         pthread_mutex_unlock(&stream->metadata_timer_lock);
1473                         (void) consumer_flush_kernel_index(stream);
1474                 } else {
1475                         pthread_mutex_unlock(&stream->metadata_timer_lock);
1476                 }
1477                 if (err < 0) {
1478                         goto end;
1479                 }
1480         }
1481
1482         err = consumer_stream_write_index(stream, &index);
1483         if (err < 0) {
1484                 goto end;
1485         }
1486
1487 end:
1488         return ret;
1489 }
1490
1491 int lttng_kconsumer_on_recv_stream(struct lttng_consumer_stream *stream)
1492 {
1493         int ret;
1494
1495         assert(stream);
1496
1497         /*
1498          * Don't create anything if this is set for streaming or should not be
1499          * monitored.
1500          */
1501         if (stream->net_seq_idx == (uint64_t) -1ULL && stream->chan->monitor) {
1502                 ret = utils_create_stream_file(stream->chan->pathname, stream->name,
1503                                 stream->chan->tracefile_size, stream->tracefile_count_current,
1504                                 stream->uid, stream->gid, NULL);
1505                 if (ret < 0) {
1506                         goto error;
1507                 }
1508                 stream->out_fd = ret;
1509                 stream->tracefile_size_current = 0;
1510
1511                 if (!stream->metadata_flag) {
1512                         struct lttng_index_file *index_file;
1513
1514                         index_file = lttng_index_file_create(stream->chan->pathname,
1515                                         stream->name, stream->uid, stream->gid,
1516                                         stream->chan->tracefile_size,
1517                                         stream->tracefile_count_current,
1518                                         CTF_INDEX_MAJOR, CTF_INDEX_MINOR);
1519                         if (!index_file) {
1520                                 goto error;
1521                         }
1522                         stream->index_file = index_file;
1523                 }
1524         }
1525
1526         if (stream->output == LTTNG_EVENT_MMAP) {
1527                 /* get the len of the mmap region */
1528                 unsigned long mmap_len;
1529
1530                 ret = kernctl_get_mmap_len(stream->wait_fd, &mmap_len);
1531                 if (ret != 0) {
1532                         PERROR("kernctl_get_mmap_len");
1533                         goto error_close_fd;
1534                 }
1535                 stream->mmap_len = (size_t) mmap_len;
1536
1537                 stream->mmap_base = mmap(NULL, stream->mmap_len, PROT_READ,
1538                                 MAP_PRIVATE, stream->wait_fd, 0);
1539                 if (stream->mmap_base == MAP_FAILED) {
1540                         PERROR("Error mmaping");
1541                         ret = -1;
1542                         goto error_close_fd;
1543                 }
1544         }
1545
1546         /* we return 0 to let the library handle the FD internally */
1547         return 0;
1548
1549 error_close_fd:
1550         if (stream->out_fd >= 0) {
1551                 int err;
1552
1553                 err = close(stream->out_fd);
1554                 assert(!err);
1555                 stream->out_fd = -1;
1556         }
1557 error:
1558         return ret;
1559 }
1560
1561 /*
1562  * Check if data is still being extracted from the buffers for a specific
1563  * stream. Consumer data lock MUST be acquired before calling this function
1564  * and the stream lock.
1565  *
1566  * Return 1 if the traced data are still getting read else 0 meaning that the
1567  * data is available for trace viewer reading.
1568  */
1569 int lttng_kconsumer_data_pending(struct lttng_consumer_stream *stream)
1570 {
1571         int ret;
1572
1573         assert(stream);
1574
1575         if (stream->endpoint_status != CONSUMER_ENDPOINT_ACTIVE) {
1576                 ret = 0;
1577                 goto end;
1578         }
1579
1580         ret = kernctl_get_next_subbuf(stream->wait_fd);
1581         if (ret == 0) {
1582                 /* There is still data so let's put back this subbuffer. */
1583                 ret = kernctl_put_subbuf(stream->wait_fd);
1584                 assert(ret == 0);
1585                 ret = 1;   /* Data is pending */
1586                 goto end;
1587         }
1588
1589         /* Data is NOT pending and ready to be read. */
1590         ret = 0;
1591
1592 end:
1593         return ret;
1594 }