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 _GNU_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 <common/common.h>
  33 #include <common/kernel-ctl/kernel-ctl.h>
  34 #include <common/sessiond-comm/sessiond-comm.h>
  35 #include <common/sessiond-comm/relayd.h>
  36 #include <common/compat/fcntl.h>
  37 #include <common/pipe.h>
  38 #include <common/relayd/relayd.h>
  39 #include <common/utils.h>
  40 #include <common/consumer-stream.h>
  41
  42 #include "kernel-consumer.h"
  43
  44 extern struct lttng_consumer_global_data consumer_data;
  45 extern int consumer_poll_timeout;
  46 extern volatile int consumer_quit;
  47
  48 /*
  49  * Take a snapshot for a specific fd
  50  *
  51  * Returns 0 on success, < 0 on error
  52  */
  53 int lttng_kconsumer_take_snapshot(struct lttng_consumer_stream *stream)
  54 {
  55         int ret = 0;
  56         int infd = stream->wait_fd;
  57
  58         ret = kernctl_snapshot(infd);
  59         if (ret != 0) {
  60                 errno = -ret;
  61                 perror("Getting sub-buffer snapshot.");
  62         }
  63
  64         return ret;
  65 }
  66
  67 /*
  68  * Get the produced position
  69  *
  70  * Returns 0 on success, < 0 on error
  71  */
  72 int lttng_kconsumer_get_produced_snapshot(struct lttng_consumer_stream *stream,
  73                 unsigned long *pos)
  74 {
  75         int ret;
  76         int infd = stream->wait_fd;
  77
  78         ret = kernctl_snapshot_get_produced(infd, pos);
  79         if (ret != 0) {
  80                 errno = -ret;
  81                 perror("kernctl_snapshot_get_produced");
  82         }
  83
  84         return ret;
  85 }
  86
  87 /*
  88  * Get the consumerd position
  89  *
  90  * Returns 0 on success, < 0 on error
  91  */
  92 int lttng_kconsumer_get_consumed_snapshot(struct lttng_consumer_stream *stream,
  93                 unsigned long *pos)
  94 {
  95         int ret;
  96         int infd = stream->wait_fd;
  97
  98         ret = kernctl_snapshot_get_consumed(infd, pos);
  99         if (ret != 0) {
 100                 errno = -ret;
 101                 perror("kernctl_snapshot_get_consumed");
 102         }
 103
 104         return ret;
 105 }
 106
 107 /*
 108  * Find a relayd and send the stream
 109  *
 110  * Returns 0 on success, < 0 on error
 111  */
 112 static
 113 int send_relayd_stream(struct lttng_consumer_stream *stream, char *path)
 114 {
 115         struct consumer_relayd_sock_pair *relayd;
 116         int ret = 0;
 117         char *stream_path;
 118
 119         if (path != NULL) {
 120                 stream_path = path;
 121         } else {
 122                 stream_path = stream->chan->pathname;
 123         }
 124         /* The stream is not metadata. Get relayd reference if exists. */
 125         rcu_read_lock();
 126         relayd = consumer_find_relayd(stream->net_seq_idx);
 127         if (relayd != NULL) {
 128                 /* Add stream on the relayd */
 129                 pthread_mutex_lock(&relayd->ctrl_sock_mutex);
 130                 ret = relayd_add_stream(&relayd->control_sock,
 131                                 stream->name, stream_path,
 132                                 &stream->relayd_stream_id,
 133                                 stream->chan->tracefile_size,
 134                                 stream->chan->tracefile_count);
 135                 pthread_mutex_unlock(&relayd->ctrl_sock_mutex);
 136                 if (ret < 0) {
 137                         goto end;
 138                 }
 139                 uatomic_inc(&relayd->refcount);
 140         } else if (stream->net_seq_idx != (uint64_t) -1ULL) {
 141                 ERR("Network sequence index %" PRIu64 " unknown. Not adding stream.",
 142                                 stream->net_seq_idx);
 143                 ret = -1;
 144                 goto end;
 145         }
 146
 147 end:
 148         rcu_read_unlock();
 149         return ret;
 150 }
 151
 152 /*
 153  * Find a relayd and close the stream
 154  */
 155 static
 156 void close_relayd_stream(struct lttng_consumer_stream *stream)
 157 {
 158         struct consumer_relayd_sock_pair *relayd;
 159
 160         /* The stream is not metadata. Get relayd reference if exists. */
 161         rcu_read_lock();
 162         relayd = consumer_find_relayd(stream->net_seq_idx);
 163         if (relayd != NULL) {
 164                 consumer_stream_relayd_close(stream, relayd);
 165         }
 166         rcu_read_unlock();
 167 }
 168
 169 /*
 170  * Take a snapshot of all the stream of a channel
 171  *
 172  * Returns 0 on success, < 0 on error
 173  */
 174 int lttng_kconsumer_snapshot_channel(uint64_t key, char *path,
 175                 uint64_t relayd_id, struct lttng_consumer_local_data *ctx)
 176 {
 177         int ret;
 178         unsigned long consumed_pos, produced_pos;
 179         struct lttng_consumer_channel *channel;
 180         struct lttng_consumer_stream *stream;
 181
 182         DBG("Kernel consumer snapshot channel %lu", key);
 183
 184         rcu_read_lock();
 185
 186         channel = consumer_find_channel(key);
 187         if (!channel) {
 188                 ERR("No channel found for key %lu", key);
 189                 ret = -1;
 190                 goto end;
 191         }
 192
 193         /* Splice is not supported yet for channel snapshot. */
 194         if (channel->output != CONSUMER_CHANNEL_MMAP) {
 195                 ERR("Unsupported output %d", channel->output);
 196                 ret = -1;
 197                 goto end;
 198         }
 199
 200         cds_list_for_each_entry(stream, &channel->stream_no_monitor_list.head,
 201                         no_monitor_node) {
 202                 /*
 203                  * Lock stream because we are about to change its state.
 204                  */
 205                 pthread_mutex_lock(&stream->lock);
 206
 207                 stream->net_seq_idx = relayd_id;
 208                 channel->relayd_id = relayd_id;
 209                 if (relayd_id != (uint64_t) -1ULL) {
 210                         ret = send_relayd_stream(stream, path);
 211                         if (ret < 0) {
 212                                 ERR("sending stream to relayd");
 213                                 goto end_unlock;
 214                         }
 215                         DBG("Stream %s sent to the relayd", stream->name);
 216                 } else {
 217                         ret = utils_create_stream_file(path, stream->name,
 218                                         stream->chan->tracefile_size, stream->tracefile_count_current,
 219                                         stream->uid, stream->gid);
 220                         if (ret < 0) {
 221                                 ERR("utils_create_stream_file");
 222                                 goto end_unlock;
 223                         }
 224
 225                         stream->out_fd = ret;
 226                         stream->tracefile_size_current = 0;
 227
 228                         DBG("Kernel consumer snapshot stream %s/%s (%lu)", path,
 229                                         stream->name, stream->key);
 230                 }
 231
 232                 ret = kernctl_buffer_flush(stream->wait_fd);
 233                 if (ret < 0) {
 234                         ERR("Failed to flush kernel metadata stream");
 235                         goto end_unlock;
 236                 }
 237
 238                 ret = lttng_kconsumer_take_snapshot(stream);
 239                 if (ret < 0) {
 240                         ERR("Taking kernel snapshot");
 241                         goto end_unlock;
 242                 }
 243
 244                 ret = lttng_kconsumer_get_produced_snapshot(stream, &produced_pos);
 245                 if (ret < 0) {
 246                         ERR("Produced kernel snapshot position");
 247                         goto end_unlock;
 248                 }
 249
 250                 ret = lttng_kconsumer_get_consumed_snapshot(stream, &consumed_pos);
 251                 if (ret < 0) {
 252                         ERR("Consumerd kernel snapshot position");
 253                         goto end_unlock;
 254                 }
 255
 256                 if (stream->max_sb_size == 0) {
 257                         ret = kernctl_get_max_subbuf_size(stream->wait_fd,
 258                                         &stream->max_sb_size);
 259                         if (ret < 0) {
 260                                 ERR("Getting kernel max_sb_size");
 261                                 goto end_unlock;
 262                         }
 263                 }
 264
 265                 while (consumed_pos < produced_pos) {
 266                         ssize_t read_len;
 267                         unsigned long len, padded_len;
 268
 269                         DBG("Kernel consumer taking snapshot at pos %lu", consumed_pos);
 270
 271                         ret = kernctl_get_subbuf(stream->wait_fd, &consumed_pos);
 272                         if (ret < 0) {
 273                                 if (errno != EAGAIN) {
 274                                         PERROR("kernctl_get_subbuf snapshot");
 275                                         goto end_unlock;
 276                                 }
 277                                 DBG("Kernel consumer get subbuf failed. Skipping it.");
 278                                 consumed_pos += stream->max_sb_size;
 279                                 continue;
 280                         }
 281
 282                         ret = kernctl_get_subbuf_size(stream->wait_fd, &len);
 283                         if (ret < 0) {
 284                                 ERR("Snapshot kernctl_get_subbuf_size");
 285                                 goto end_unlock;
 286                         }
 287
 288                         ret = kernctl_get_padded_subbuf_size(stream->wait_fd, &padded_len);
 289                         if (ret < 0) {
 290                                 ERR("Snapshot kernctl_get_padded_subbuf_size");
 291                                 goto end_unlock;
 292                         }
 293
 294                         read_len = lttng_consumer_on_read_subbuffer_mmap(ctx, stream, len,
 295                                         padded_len - len);
 296                         /*
 297                          * We write the padded len in local tracefiles but the
 298                          * data len when using a relay.
 299                          * Display the error but continue processing to try to
 300                          * release the subbuffer.
 301                          */
 302                         if (relayd_id != (uint64_t) -1ULL) {
 303                                 if (read_len != len) {
 304                                         ERR("Error sending to the relay (ret: %zd != len: %lu)",
 305                                                         read_len, len);
 306                                 }
 307                         } else {
 308                                 if (read_len != padded_len) {
 309                                         ERR("Error writing to tracefile (ret: %zd != len: %lu)",
 310                                                         read_len, padded_len);
 311                                 }
 312                         }
 313
 314                         ret = kernctl_put_subbuf(stream->wait_fd);
 315                         if (ret < 0) {
 316                                 ERR("Snapshot kernctl_put_subbuf");
 317                                 goto end_unlock;
 318                         }
 319                         consumed_pos += stream->max_sb_size;
 320                 }
 321
 322                 if (relayd_id == (uint64_t) -1ULL) {
 323                         ret = close(stream->out_fd);
 324                         if (ret < 0) {
 325                                 PERROR("Kernel consumer snapshot close out_fd");
 326                                 goto end_unlock;
 327                         }
 328                         stream->out_fd = -1;
 329                 } else {
 330                         close_relayd_stream(stream);
 331                         stream->net_seq_idx = (uint64_t) -1ULL;
 332                 }
 333                 pthread_mutex_unlock(&stream->lock);
 334         }
 335
 336         /* All good! */
 337         ret = 0;
 338         goto end;
 339
 340 end_unlock:
 341         pthread_mutex_unlock(&stream->lock);
 342 end:
 343         rcu_read_unlock();
 344         return ret;
 345 }
 346
 347 /*
 348  * Read the whole metadata available for a snapshot.
 349  *
 350  * Returns 0 on success, < 0 on error
 351  */
 352 int lttng_kconsumer_snapshot_metadata(uint64_t key, char *path,
 353                 uint64_t relayd_id, struct lttng_consumer_local_data *ctx)
 354 {
 355         struct lttng_consumer_channel *metadata_channel;
 356         struct lttng_consumer_stream *metadata_stream;
 357         int ret;
 358
 359         DBG("Kernel consumer snapshot metadata with key %" PRIu64 " at path %s",
 360                         key, path);
 361
 362         rcu_read_lock();
 363
 364         metadata_channel = consumer_find_channel(key);
 365         if (!metadata_channel) {
 366                 ERR("Snapshot kernel metadata channel not found for key %lu", key);
 367                 ret = -1;
 368                 goto end;
 369         }
 370
 371         metadata_stream = metadata_channel->metadata_stream;
 372         assert(metadata_stream);
 373
 374         if (relayd_id != (uint64_t) -1ULL) {
 375                 ret = send_relayd_stream(metadata_stream, path);
 376                 if (ret < 0) {
 377                         ERR("sending stream to relayd");
 378                 }
 379                 DBG("Stream %s sent to the relayd", metadata_stream->name);
 380         } else {
 381                 ret = utils_create_stream_file(path, metadata_stream->name,
 382                                 metadata_stream->chan->tracefile_size,
 383                                 metadata_stream->tracefile_count_current,
 384                                 metadata_stream->uid, metadata_stream->gid);
 385                 if (ret < 0) {
 386                         goto end;
 387                 }
 388                 metadata_stream->out_fd = ret;
 389         }
 390
 391         ret = 0;
 392         while (ret >= 0) {
 393                 ret = lttng_kconsumer_read_subbuffer(metadata_stream, ctx);
 394                 if (ret < 0) {
 395                         if (ret != -EPERM) {
 396                                 ERR("Kernel snapshot reading subbuffer");
 397                                 goto end;
 398                         }
 399                         /* "ret" is negative at this point so we will exit the loop. */
 400                         continue;
 401                 }
 402         }
 403
 404         if (relayd_id == (uint64_t) -1ULL) {
 405                 ret = close(metadata_stream->out_fd);
 406                 if (ret < 0) {
 407                         PERROR("Kernel consumer snapshot close out_fd");
 408                         goto end;
 409                 }
 410                 metadata_stream->out_fd = -1;
 411         } else {
 412                 close_relayd_stream(metadata_stream);
 413                 metadata_stream->net_seq_idx = (uint64_t) -1ULL;
 414         }
 415
 416         ret = 0;
 417 end:
 418         rcu_read_unlock();
 419         return ret;
 420 }
 421
 422 /*
 423  * Receive command from session daemon and process it.
 424  *
 425  * Return 1 on success else a negative value or 0.
 426  */
 427 int lttng_kconsumer_recv_cmd(struct lttng_consumer_local_data *ctx,
 428                 int sock, struct pollfd *consumer_sockpoll)
 429 {
 430         ssize_t ret;
 431         enum lttng_error_code ret_code = LTTNG_OK;
 432         struct lttcomm_consumer_msg msg;
 433
 434         ret = lttcomm_recv_unix_sock(sock, &msg, sizeof(msg));
 435         if (ret != sizeof(msg)) {
 436                 lttng_consumer_send_error(ctx, LTTCOMM_CONSUMERD_ERROR_RECV_CMD);
 437                 if (ret > 0) {
 438                         ret = -1;
 439                 }
 440                 return ret;
 441         }
 442         if (msg.cmd_type == LTTNG_CONSUMER_STOP) {
 443                 /*
 444                  * Notify the session daemon that the command is completed.
 445                  *
 446                  * On transport layer error, the function call will print an error
 447                  * message so handling the returned code is a bit useless since we
 448                  * return an error code anyway.
 449                  */
 450                 (void) consumer_send_status_msg(sock, ret_code);
 451                 return -ENOENT;
 452         }
 453
 454         /* relayd needs RCU read-side protection */
 455         rcu_read_lock();
 456
 457         switch (msg.cmd_type) {
 458         case LTTNG_CONSUMER_ADD_RELAYD_SOCKET:
 459         {
 460                 /* Session daemon status message are handled in the following call. */
 461                 ret = consumer_add_relayd_socket(msg.u.relayd_sock.net_index,
 462                                 msg.u.relayd_sock.type, ctx, sock, consumer_sockpoll,
 463                                 &msg.u.relayd_sock.sock, msg.u.relayd_sock.session_id);
 464                 goto end_nosignal;
 465         }
 466         case LTTNG_CONSUMER_ADD_CHANNEL:
 467         {
 468                 struct lttng_consumer_channel *new_channel;
 469                 int ret_recv;
 470
 471                 /* First send a status message before receiving the fds. */
 472                 ret = consumer_send_status_msg(sock, ret_code);
 473                 if (ret < 0) {
 474                         /* Somehow, the session daemon is not responding anymore. */
 475                         goto error_fatal;
 476                 }
 477                 DBG("consumer_add_channel %" PRIu64, msg.u.channel.channel_key);
 478                 new_channel = consumer_allocate_channel(msg.u.channel.channel_key,
 479                                 msg.u.channel.session_id, msg.u.channel.pathname,
 480                                 msg.u.channel.name, msg.u.channel.uid, msg.u.channel.gid,
 481                                 msg.u.channel.relayd_id, msg.u.channel.output,
 482                                 msg.u.channel.tracefile_size,
 483                                 msg.u.channel.tracefile_count,
 484                                 msg.u.channel.monitor);
 485                 if (new_channel == NULL) {
 486                         lttng_consumer_send_error(ctx, LTTCOMM_CONSUMERD_OUTFD_ERROR);
 487                         goto end_nosignal;
 488                 }
 489                 new_channel->nb_init_stream_left = msg.u.channel.nb_init_streams;
 490
 491                 /* Translate and save channel type. */
 492                 switch (msg.u.channel.type) {
 493                 case CONSUMER_CHANNEL_TYPE_DATA:
 494                 case CONSUMER_CHANNEL_TYPE_METADATA:
 495                         new_channel->type = msg.u.channel.type;
 496                         break;
 497                 default:
 498                         assert(0);
 499                         goto end_nosignal;
 500                 };
 501
 502                 if (ctx->on_recv_channel != NULL) {
 503                         ret_recv = ctx->on_recv_channel(new_channel);
 504                         if (ret_recv == 0) {
 505                                 ret = consumer_add_channel(new_channel, ctx);
 506                         } else if (ret_recv < 0) {
 507                                 goto end_nosignal;
 508                         }
 509                 } else {
 510                         ret = consumer_add_channel(new_channel, ctx);
 511                 }
 512
 513                 /* If we received an error in add_channel, we need to report it. */
 514                 if (ret < 0) {
 515                         ret = consumer_send_status_msg(sock, ret);
 516                         if (ret < 0) {
 517                                 goto error_fatal;
 518                         }
 519                         goto end_nosignal;
 520                 }
 521
 522                 goto end_nosignal;
 523         }
 524         case LTTNG_CONSUMER_ADD_STREAM:
 525         {
 526                 int fd;
 527                 struct lttng_pipe *stream_pipe;
 528                 struct lttng_consumer_stream *new_stream;
 529                 struct lttng_consumer_channel *channel;
 530                 int alloc_ret = 0;
 531
 532                 /*
 533                  * Get stream's channel reference. Needed when adding the stream to the
 534                  * global hash table.
 535                  */
 536                 channel = consumer_find_channel(msg.u.stream.channel_key);
 537                 if (!channel) {
 538                         /*
 539                          * We could not find the channel. Can happen if cpu hotplug
 540                          * happens while tearing down.
 541                          */
 542                         ERR("Unable to find channel key %" PRIu64, msg.u.stream.channel_key);
 543                         ret_code = LTTNG_ERR_KERN_CHAN_NOT_FOUND;
 544                 }
 545
 546                 /* First send a status message before receiving the fds. */
 547                 ret = consumer_send_status_msg(sock, ret_code);
 548                 if (ret < 0) {
 549                         /*
 550                          * Somehow, the session daemon is not responding
 551                          * anymore.
 552                          */
 553                         goto error_fatal;
 554                 }
 555                 if (ret_code != LTTNG_OK) {
 556                         /*
 557                          * Channel was not found.
 558                          */
 559                         goto end_nosignal;
 560                 }
 561
 562                 /* block */
 563                 if (lttng_consumer_poll_socket(consumer_sockpoll) < 0) {
 564                         rcu_read_unlock();
 565                         return -EINTR;
 566                 }
 567
 568                 /* Get stream file descriptor from socket */
 569                 ret = lttcomm_recv_fds_unix_sock(sock, &fd, 1);
 570                 if (ret != sizeof(fd)) {
 571                         lttng_consumer_send_error(ctx, LTTCOMM_CONSUMERD_ERROR_RECV_FD);
 572                         rcu_read_unlock();
 573                         return ret;
 574                 }
 575
 576                 /*
 577                  * Send status code to session daemon only if the recv works. If the
 578                  * above recv() failed, the session daemon is notified through the
 579                  * error socket and the teardown is eventually done.
 580                  */
 581                 ret = consumer_send_status_msg(sock, ret_code);
 582                 if (ret < 0) {
 583                         /* Somehow, the session daemon is not responding anymore. */
 584                         goto end_nosignal;
 585                 }
 586
 587                 new_stream = consumer_allocate_stream(channel->key,
 588                                 fd,
 589                                 LTTNG_CONSUMER_ACTIVE_STREAM,
 590                                 channel->name,
 591                                 channel->uid,
 592                                 channel->gid,
 593                                 channel->relayd_id,
 594                                 channel->session_id,
 595                                 msg.u.stream.cpu,
 596                                 &alloc_ret,
 597                                 channel->type);
 598                 if (new_stream == NULL) {
 599                         switch (alloc_ret) {
 600                         case -ENOMEM:
 601                         case -EINVAL:
 602                         default:
 603                                 lttng_consumer_send_error(ctx, LTTCOMM_CONSUMERD_OUTFD_ERROR);
 604                                 break;
 605                         }
 606                         goto end_nosignal;
 607                 }
 608                 new_stream->chan = channel;
 609                 new_stream->wait_fd = fd;
 610                 switch (channel->output) {
 611                 case CONSUMER_CHANNEL_SPLICE:
 612                         new_stream->output = LTTNG_EVENT_SPLICE;
 613                         break;
 614                 case CONSUMER_CHANNEL_MMAP:
 615                         new_stream->output = LTTNG_EVENT_MMAP;
 616                         break;
 617                 default:
 618                         ERR("Stream output unknown %d", channel->output);
 619                         goto end_nosignal;
 620                 }
 621
 622                 /*
 623                  * We've just assigned the channel to the stream so increment the
 624                  * refcount right now. We don't need to increment the refcount for
 625                  * streams in no monitor because we handle manually the cleanup of
 626                  * those. It is very important to make sure there is NO prior
 627                  * consumer_del_stream() calls or else the refcount will be unbalanced.
 628                  */
 629                 if (channel->monitor) {
 630                         uatomic_inc(&new_stream->chan->refcount);
 631                 }
 632
 633                 /*
 634                  * The buffer flush is done on the session daemon side for the kernel
 635                  * so no need for the stream "hangup_flush_done" variable to be
 636                  * tracked. This is important for a kernel stream since we don't rely
 637                  * on the flush state of the stream to read data. It's not the case for
 638                  * user space tracing.
 639                  */
 640                 new_stream->hangup_flush_done = 0;
 641
 642                 if (ctx->on_recv_stream) {
 643                         ret = ctx->on_recv_stream(new_stream);
 644                         if (ret < 0) {
 645                                 consumer_del_stream(new_stream, NULL);
 646                                 goto end_nosignal;
 647                         }
 648                 }
 649
 650                 if (new_stream->metadata_flag) {
 651                         channel->metadata_stream = new_stream;
 652                 }
 653
 654                 /* Do not monitor this stream. */
 655                 if (!channel->monitor) {
 656                         DBG("Kernel consumer add stream %s in no monitor mode with"
 657                                         "relayd id %" PRIu64, new_stream->name,
 658                                         new_stream->relayd_stream_id);
 659                         cds_list_add(&new_stream->no_monitor_node,
 660                                         &channel->stream_no_monitor_list.head);
 661                         break;
 662                 }
 663
 664                 ret = send_relayd_stream(new_stream, NULL);
 665                 if (ret < 0) {
 666                         consumer_del_stream(new_stream, NULL);
 667                         goto end_nosignal;
 668                 }
 669
 670                 /* Get the right pipe where the stream will be sent. */
 671                 if (new_stream->metadata_flag) {
 672                         stream_pipe = ctx->consumer_metadata_pipe;
 673                 } else {
 674                         stream_pipe = ctx->consumer_data_pipe;
 675                 }
 676
 677                 ret = lttng_pipe_write(stream_pipe, &new_stream, sizeof(new_stream));
 678                 if (ret < 0) {
 679                         ERR("Consumer write %s stream to pipe %d",
 680                                         new_stream->metadata_flag ? "metadata" : "data",
 681                                         lttng_pipe_get_writefd(stream_pipe));
 682                         consumer_del_stream(new_stream, NULL);
 683                         goto end_nosignal;
 684                 }
 685
 686                 DBG("Kernel consumer ADD_STREAM %s (fd: %d) with relayd id %" PRIu64,
 687                                 new_stream->name, fd, new_stream->relayd_stream_id);
 688                 break;
 689         }
 690         case LTTNG_CONSUMER_UPDATE_STREAM:
 691         {
 692                 rcu_read_unlock();
 693                 return -ENOSYS;
 694         }
 695         case LTTNG_CONSUMER_DESTROY_RELAYD:
 696         {
 697                 uint64_t index = msg.u.destroy_relayd.net_seq_idx;
 698                 struct consumer_relayd_sock_pair *relayd;
 699
 700                 DBG("Kernel consumer destroying relayd %" PRIu64, index);
 701
 702                 /* Get relayd reference if exists. */
 703                 relayd = consumer_find_relayd(index);
 704                 if (relayd == NULL) {
 705                         DBG("Unable to find relayd %" PRIu64, index);
 706                         ret_code = LTTNG_ERR_NO_CONSUMER;
 707                 }
 708
 709                 /*
 710                  * Each relayd socket pair has a refcount of stream attached to it
 711                  * which tells if the relayd is still active or not depending on the
 712                  * refcount value.
 713                  *
 714                  * This will set the destroy flag of the relayd object and destroy it
 715                  * if the refcount reaches zero when called.
 716                  *
 717                  * The destroy can happen either here or when a stream fd hangs up.
 718                  */
 719                 if (relayd) {
 720                         consumer_flag_relayd_for_destroy(relayd);
 721                 }
 722
 723                 ret = consumer_send_status_msg(sock, ret_code);
 724                 if (ret < 0) {
 725                         /* Somehow, the session daemon is not responding anymore. */
 726                         goto error_fatal;
 727                 }
 728
 729                 goto end_nosignal;
 730         }
 731         case LTTNG_CONSUMER_DATA_PENDING:
 732         {
 733                 int32_t ret;
 734                 uint64_t id = msg.u.data_pending.session_id;
 735
 736                 DBG("Kernel consumer data pending command for id %" PRIu64, id);
 737
 738                 ret = consumer_data_pending(id);
 739
 740                 /* Send back returned value to session daemon */
 741                 ret = lttcomm_send_unix_sock(sock, &ret, sizeof(ret));
 742                 if (ret < 0) {
 743                         PERROR("send data pending ret code");
 744                         goto error_fatal;
 745                 }
 746
 747                 /*
 748                  * No need to send back a status message since the data pending
 749                  * returned value is the response.
 750                  */
 751                 break;
 752         }
 753         case LTTNG_CONSUMER_SNAPSHOT_CHANNEL:
 754         {
 755                 if (msg.u.snapshot_channel.metadata == 1) {
 756                         ret = lttng_kconsumer_snapshot_metadata(msg.u.snapshot_channel.key,
 757                                         msg.u.snapshot_channel.pathname,
 758                                         msg.u.snapshot_channel.relayd_id, ctx);
 759                         if (ret < 0) {
 760                                 ERR("Snapshot metadata failed");
 761                                 ret_code = LTTNG_ERR_KERN_META_FAIL;
 762                         }
 763                 } else {
 764                         ret = lttng_kconsumer_snapshot_channel(msg.u.snapshot_channel.key,
 765                                         msg.u.snapshot_channel.pathname,
 766                                         msg.u.snapshot_channel.relayd_id, ctx);
 767                         if (ret < 0) {
 768                                 ERR("Snapshot channel failed");
 769                                 ret_code = LTTNG_ERR_KERN_CHAN_FAIL;
 770                         }
 771                 }
 772
 773                 ret = consumer_send_status_msg(sock, ret_code);
 774                 if (ret < 0) {
 775                         /* Somehow, the session daemon is not responding anymore. */
 776                         goto end_nosignal;
 777                 }
 778                 break;
 779         }
 780         case LTTNG_CONSUMER_DESTROY_CHANNEL:
 781         {
 782                 uint64_t key = msg.u.destroy_channel.key;
 783                 struct lttng_consumer_channel *channel;
 784
 785                 channel = consumer_find_channel(key);
 786                 if (!channel) {
 787                         ERR("Kernel consumer destroy channel %" PRIu64 " not found", key);
 788                         ret_code = LTTNG_ERR_KERN_CHAN_NOT_FOUND;
 789                 }
 790
 791                 ret = consumer_send_status_msg(sock, ret_code);
 792                 if (ret < 0) {
 793                         /* Somehow, the session daemon is not responding anymore. */
 794                         goto end_nosignal;
 795                 }
 796
 797                 /*
 798                  * This command should ONLY be issued for channel with streams set in
 799                  * no monitor mode.
 800                  */
 801                 assert(!channel->monitor);
 802
 803                 /*
 804                  * The refcount should ALWAYS be 0 in the case of a channel in no
 805                  * monitor mode.
 806                  */
 807                 assert(!uatomic_sub_return(&channel->refcount, 1));
 808
 809                 consumer_del_channel(channel);
 810
 811                 goto end_nosignal;
 812         }
 813         default:
 814                 goto end_nosignal;
 815         }
 816
 817 end_nosignal:
 818         rcu_read_unlock();
 819
 820         /*
 821          * Return 1 to indicate success since the 0 value can be a socket
 822          * shutdown during the recv() or send() call.
 823          */
 824         return 1;
 825
 826 error_fatal:
 827         rcu_read_unlock();
 828         /* This will issue a consumer stop. */
 829         return -1;
 830 }
 831
 832 /*
 833  * Consume data on a file descriptor and write it on a trace file.
 834  */
 835 ssize_t lttng_kconsumer_read_subbuffer(struct lttng_consumer_stream *stream,
 836                 struct lttng_consumer_local_data *ctx)
 837 {
 838         unsigned long len, subbuf_size, padding;
 839         int err;
 840         ssize_t ret = 0;
 841         int infd = stream->wait_fd;
 842
 843         DBG("In read_subbuffer (infd : %d)", infd);
 844         /* Get the next subbuffer */
 845         err = kernctl_get_next_subbuf(infd);
 846         if (err != 0) {
 847                 ret = err;
 848                 /*
 849                  * This is a debug message even for single-threaded consumer,
 850                  * because poll() have more relaxed criterions than get subbuf,
 851                  * so get_subbuf may fail for short race windows where poll()
 852                  * would issue wakeups.
 853                  */
 854                 DBG("Reserving sub buffer failed (everything is normal, "
 855                                 "it is due to concurrency)");
 856                 goto end;
 857         }
 858
 859         /* Get the full subbuffer size including padding */
 860         err = kernctl_get_padded_subbuf_size(infd, &len);
 861         if (err != 0) {
 862                 errno = -err;
 863                 perror("Getting sub-buffer len failed.");
 864                 ret = err;
 865                 goto end;
 866         }
 867
 868         switch (stream->chan->output) {
 869         case CONSUMER_CHANNEL_SPLICE:
 870                 /*
 871                  * XXX: The lttng-modules splice "actor" does not handle copying
 872                  * partial pages hence only using the subbuffer size without the
 873                  * padding makes the splice fail.
 874                  */
 875                 subbuf_size = len;
 876                 padding = 0;
 877
 878                 /* splice the subbuffer to the tracefile */
 879                 ret = lttng_consumer_on_read_subbuffer_splice(ctx, stream, subbuf_size,
 880                                 padding);
 881                 /*
 882                  * XXX: Splice does not support network streaming so the return value
 883                  * is simply checked against subbuf_size and not like the mmap() op.
 884                  */
 885                 if (ret != subbuf_size) {
 886                         /*
 887                          * display the error but continue processing to try
 888                          * to release the subbuffer
 889                          */
 890                         ERR("Error splicing to tracefile (ret: %zd != len: %lu)",
 891                                         ret, subbuf_size);
 892                 }
 893                 break;
 894         case CONSUMER_CHANNEL_MMAP:
 895                 /* Get subbuffer size without padding */
 896                 err = kernctl_get_subbuf_size(infd, &subbuf_size);
 897                 if (err != 0) {
 898                         errno = -err;
 899                         perror("Getting sub-buffer len failed.");
 900                         ret = err;
 901                         goto end;
 902                 }
 903
 904                 /* Make sure the tracer is not gone mad on us! */
 905                 assert(len >= subbuf_size);
 906
 907                 padding = len - subbuf_size;
 908
 909                 /* write the subbuffer to the tracefile */
 910                 ret = lttng_consumer_on_read_subbuffer_mmap(ctx, stream, subbuf_size,
 911                                 padding);
 912                 /*
 913                  * The mmap operation should write subbuf_size amount of data when
 914                  * network streaming or the full padding (len) size when we are _not_
 915                  * streaming.
 916                  */
 917                 if ((ret != subbuf_size && stream->net_seq_idx != (uint64_t) -1ULL) ||
 918                                 (ret != len && stream->net_seq_idx == (uint64_t) -1ULL)) {
 919                         /*
 920                          * Display the error but continue processing to try to release the
 921                          * subbuffer
 922                          */
 923                         ERR("Error writing to tracefile "
 924                                         "(ret: %zd != len: %lu != subbuf_size: %lu)",
 925                                         ret, len, subbuf_size);
 926                 }
 927                 break;
 928         default:
 929                 ERR("Unknown output method");
 930                 ret = -1;
 931         }
 932
 933         err = kernctl_put_next_subbuf(infd);
 934         if (err != 0) {
 935                 errno = -err;
 936                 if (errno == EFAULT) {
 937                         perror("Error in unreserving sub buffer\n");
 938                 } else if (errno == EIO) {
 939                         /* Should never happen with newer LTTng versions */
 940                         perror("Reader has been pushed by the writer, last sub-buffer corrupted.");
 941                 }
 942
 943                 ret = -err;
 944                 goto end;
 945         }
 946
 947 end:
 948         return ret;
 949 }
 950
 951 int lttng_kconsumer_on_recv_stream(struct lttng_consumer_stream *stream)
 952 {
 953         int ret;
 954
 955         assert(stream);
 956
 957         /*
 958          * Don't create anything if this is set for streaming or should not be
 959          * monitored.
 960          */
 961         if (stream->net_seq_idx == (uint64_t) -1ULL && stream->chan->monitor) {
 962                 ret = utils_create_stream_file(stream->chan->pathname, stream->name,
 963                                 stream->chan->tracefile_size, stream->tracefile_count_current,
 964                                 stream->uid, stream->gid);
 965                 if (ret < 0) {
 966                         goto error;
 967                 }
 968                 stream->out_fd = ret;
 969                 stream->tracefile_size_current = 0;
 970         }
 971
 972         if (stream->output == LTTNG_EVENT_MMAP) {
 973                 /* get the len of the mmap region */
 974                 unsigned long mmap_len;
 975
 976                 ret = kernctl_get_mmap_len(stream->wait_fd, &mmap_len);
 977                 if (ret != 0) {
 978                         errno = -ret;
 979                         PERROR("kernctl_get_mmap_len");
 980                         goto error_close_fd;
 981                 }
 982                 stream->mmap_len = (size_t) mmap_len;
 983
 984                 stream->mmap_base = mmap(NULL, stream->mmap_len, PROT_READ,
 985                                 MAP_PRIVATE, stream->wait_fd, 0);
 986                 if (stream->mmap_base == MAP_FAILED) {
 987                         PERROR("Error mmaping");
 988                         ret = -1;
 989                         goto error_close_fd;
 990                 }
 991         }
 992
 993         /* we return 0 to let the library handle the FD internally */
 994         return 0;
 995
 996 error_close_fd:
 997         {
 998                 int err;
 999
1000                 err = close(stream->out_fd);
1001                 assert(!err);
1002         }
1003 error:
1004         return ret;
1005 }
1006
1007 /*
1008  * Check if data is still being extracted from the buffers for a specific
1009  * stream. Consumer data lock MUST be acquired before calling this function
1010  * and the stream lock.
1011  *
1012  * Return 1 if the traced data are still getting read else 0 meaning that the
1013  * data is available for trace viewer reading.
1014  */
1015 int lttng_kconsumer_data_pending(struct lttng_consumer_stream *stream)
1016 {
1017         int ret;
1018
1019         assert(stream);
1020
1021         ret = kernctl_get_next_subbuf(stream->wait_fd);
1022         if (ret == 0) {
1023                 /* There is still data so let's put back this subbuffer. */
1024                 ret = kernctl_put_subbuf(stream->wait_fd);
1025                 assert(ret == 0);
1026                 ret = 1;   /* Data is pending */
1027                 goto end;
1028         }
1029
1030         /* Data is NOT pending and ready to be read. */
1031         ret = 0;
1032
1033 end:
1034         return ret;
1035 }