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                 /*
 208                  * Assign the received relayd ID so we can use it for streaming. The streams
 209                  * are not visible to anyone so this is OK to change it.
 210                  */
 211                 stream->net_seq_idx = relayd_id;
 212                 channel->relayd_id = relayd_id;
 213                 if (relayd_id != (uint64_t) -1ULL) {
 214                         ret = send_relayd_stream(stream, path);
 215                         if (ret < 0) {
 216                                 ERR("sending stream to relayd");
 217                                 goto end_unlock;
 218                         }
 219                         DBG("Stream %s sent to the relayd", stream->name);
 220                 } else {
 221                         ret = utils_create_stream_file(path, stream->name,
 222                                         stream->chan->tracefile_size, stream->tracefile_count_current,
 223                                         stream->uid, stream->gid);
 224                         if (ret < 0) {
 225                                 ERR("utils_create_stream_file");
 226                                 goto end_unlock;
 227                         }
 228
 229                         stream->out_fd = ret;
 230                         stream->tracefile_size_current = 0;
 231
 232                         DBG("Kernel consumer snapshot stream %s/%s (%lu)", path,
 233                                         stream->name, stream->key);
 234                 }
 235
 236                 ret = kernctl_buffer_flush(stream->wait_fd);
 237                 if (ret < 0) {
 238                         ERR("Failed to flush kernel metadata stream");
 239                         goto end_unlock;
 240                 }
 241
 242                 ret = lttng_kconsumer_take_snapshot(stream);
 243                 if (ret < 0) {
 244                         ERR("Taking kernel snapshot");
 245                         goto end_unlock;
 246                 }
 247
 248                 ret = lttng_kconsumer_get_produced_snapshot(stream, &produced_pos);
 249                 if (ret < 0) {
 250                         ERR("Produced kernel snapshot position");
 251                         goto end_unlock;
 252                 }
 253
 254                 ret = lttng_kconsumer_get_consumed_snapshot(stream, &consumed_pos);
 255                 if (ret < 0) {
 256                         ERR("Consumerd kernel snapshot position");
 257                         goto end_unlock;
 258                 }
 259
 260                 if (stream->max_sb_size == 0) {
 261                         ret = kernctl_get_max_subbuf_size(stream->wait_fd,
 262                                         &stream->max_sb_size);
 263                         if (ret < 0) {
 264                                 ERR("Getting kernel max_sb_size");
 265                                 goto end_unlock;
 266                         }
 267                 }
 268
 269                 while (consumed_pos < produced_pos) {
 270                         ssize_t read_len;
 271                         unsigned long len, padded_len;
 272
 273                         DBG("Kernel consumer taking snapshot at pos %lu", consumed_pos);
 274
 275                         ret = kernctl_get_subbuf(stream->wait_fd, &consumed_pos);
 276                         if (ret < 0) {
 277                                 if (errno != EAGAIN) {
 278                                         PERROR("kernctl_get_subbuf snapshot");
 279                                         goto end_unlock;
 280                                 }
 281                                 DBG("Kernel consumer get subbuf failed. Skipping it.");
 282                                 consumed_pos += stream->max_sb_size;
 283                                 continue;
 284                         }
 285
 286                         ret = kernctl_get_subbuf_size(stream->wait_fd, &len);
 287                         if (ret < 0) {
 288                                 ERR("Snapshot kernctl_get_subbuf_size");
 289                                 goto error_put_subbuf;
 290                         }
 291
 292                         ret = kernctl_get_padded_subbuf_size(stream->wait_fd, &padded_len);
 293                         if (ret < 0) {
 294                                 ERR("Snapshot kernctl_get_padded_subbuf_size");
 295                                 goto error_put_subbuf;
 296                         }
 297
 298                         read_len = lttng_consumer_on_read_subbuffer_mmap(ctx, stream, len,
 299                                         padded_len - len);
 300                         /*
 301                          * We write the padded len in local tracefiles but the data len
 302                          * when using a relay. Display the error but continue processing
 303                          * to try to release the subbuffer.
 304                          */
 305                         if (relayd_id != (uint64_t) -1ULL) {
 306                                 if (read_len != len) {
 307                                         ERR("Error sending to the relay (ret: %zd != len: %lu)",
 308                                                         read_len, len);
 309                                 }
 310                         } else {
 311                                 if (read_len != padded_len) {
 312                                         ERR("Error writing to tracefile (ret: %zd != len: %lu)",
 313                                                         read_len, padded_len);
 314                                 }
 315                         }
 316
 317                         ret = kernctl_put_subbuf(stream->wait_fd);
 318                         if (ret < 0) {
 319                                 ERR("Snapshot kernctl_put_subbuf");
 320                                 goto end_unlock;
 321                         }
 322                         consumed_pos += stream->max_sb_size;
 323                 }
 324
 325                 if (relayd_id == (uint64_t) -1ULL) {
 326                         ret = close(stream->out_fd);
 327                         if (ret < 0) {
 328                                 PERROR("Kernel consumer snapshot close out_fd");
 329                                 goto end_unlock;
 330                         }
 331                         stream->out_fd = -1;
 332                 } else {
 333                         close_relayd_stream(stream);
 334                         stream->net_seq_idx = (uint64_t) -1ULL;
 335                 }
 336                 pthread_mutex_unlock(&stream->lock);
 337         }
 338
 339         /* All good! */
 340         ret = 0;
 341         goto end;
 342
 343 error_put_subbuf:
 344         ret = kernctl_put_subbuf(stream->wait_fd);
 345         if (ret < 0) {
 346                 ERR("Snapshot kernctl_put_subbuf error path");
 347         }
 348 end_unlock:
 349         pthread_mutex_unlock(&stream->lock);
 350 end:
 351         rcu_read_unlock();
 352         return ret;
 353 }
 354
 355 /*
 356  * Read the whole metadata available for a snapshot.
 357  *
 358  * Returns 0 on success, < 0 on error
 359  */
 360 int lttng_kconsumer_snapshot_metadata(uint64_t key, char *path,
 361                 uint64_t relayd_id, struct lttng_consumer_local_data *ctx)
 362 {
 363         struct lttng_consumer_channel *metadata_channel;
 364         struct lttng_consumer_stream *metadata_stream;
 365         int ret;
 366
 367         DBG("Kernel consumer snapshot metadata with key %" PRIu64 " at path %s",
 368                         key, path);
 369
 370         rcu_read_lock();
 371
 372         metadata_channel = consumer_find_channel(key);
 373         if (!metadata_channel) {
 374                 ERR("Snapshot kernel metadata channel not found for key %lu", key);
 375                 ret = -1;
 376                 goto end;
 377         }
 378
 379         metadata_stream = metadata_channel->metadata_stream;
 380         assert(metadata_stream);
 381
 382         if (relayd_id != (uint64_t) -1ULL) {
 383                 ret = send_relayd_stream(metadata_stream, path);
 384                 if (ret < 0) {
 385                         ERR("sending stream to relayd");
 386                 }
 387                 DBG("Stream %s sent to the relayd", metadata_stream->name);
 388         } else {
 389                 ret = utils_create_stream_file(path, metadata_stream->name,
 390                                 metadata_stream->chan->tracefile_size,
 391                                 metadata_stream->tracefile_count_current,
 392                                 metadata_stream->uid, metadata_stream->gid);
 393                 if (ret < 0) {
 394                         goto end;
 395                 }
 396                 metadata_stream->out_fd = ret;
 397         }
 398
 399         ret = 0;
 400         while (ret >= 0) {
 401                 ret = lttng_kconsumer_read_subbuffer(metadata_stream, ctx);
 402                 if (ret < 0) {
 403                         if (ret != -EPERM) {
 404                                 ERR("Kernel snapshot reading subbuffer");
 405                                 goto end;
 406                         }
 407                         /* "ret" is negative at this point so we will exit the loop. */
 408                         continue;
 409                 }
 410         }
 411
 412         if (relayd_id == (uint64_t) -1ULL) {
 413                 ret = close(metadata_stream->out_fd);
 414                 if (ret < 0) {
 415                         PERROR("Kernel consumer snapshot close out_fd");
 416                         goto end;
 417                 }
 418                 metadata_stream->out_fd = -1;
 419         } else {
 420                 close_relayd_stream(metadata_stream);
 421                 metadata_stream->net_seq_idx = (uint64_t) -1ULL;
 422         }
 423
 424         ret = 0;
 425 end:
 426         rcu_read_unlock();
 427         return ret;
 428 }
 429
 430 /*
 431  * Receive command from session daemon and process it.
 432  *
 433  * Return 1 on success else a negative value or 0.
 434  */
 435 int lttng_kconsumer_recv_cmd(struct lttng_consumer_local_data *ctx,
 436                 int sock, struct pollfd *consumer_sockpoll)
 437 {
 438         ssize_t ret;
 439         enum lttng_error_code ret_code = LTTNG_OK;
 440         struct lttcomm_consumer_msg msg;
 441
 442         ret = lttcomm_recv_unix_sock(sock, &msg, sizeof(msg));
 443         if (ret != sizeof(msg)) {
 444                 lttng_consumer_send_error(ctx, LTTCOMM_CONSUMERD_ERROR_RECV_CMD);
 445                 if (ret > 0) {
 446                         ret = -1;
 447                 }
 448                 return ret;
 449         }
 450         if (msg.cmd_type == LTTNG_CONSUMER_STOP) {
 451                 /*
 452                  * Notify the session daemon that the command is completed.
 453                  *
 454                  * On transport layer error, the function call will print an error
 455                  * message so handling the returned code is a bit useless since we
 456                  * return an error code anyway.
 457                  */
 458                 (void) consumer_send_status_msg(sock, ret_code);
 459                 return -ENOENT;
 460         }
 461
 462         /* relayd needs RCU read-side protection */
 463         rcu_read_lock();
 464
 465         switch (msg.cmd_type) {
 466         case LTTNG_CONSUMER_ADD_RELAYD_SOCKET:
 467         {
 468                 /* Session daemon status message are handled in the following call. */
 469                 ret = consumer_add_relayd_socket(msg.u.relayd_sock.net_index,
 470                                 msg.u.relayd_sock.type, ctx, sock, consumer_sockpoll,
 471                                 &msg.u.relayd_sock.sock, msg.u.relayd_sock.session_id);
 472                 goto end_nosignal;
 473         }
 474         case LTTNG_CONSUMER_ADD_CHANNEL:
 475         {
 476                 struct lttng_consumer_channel *new_channel;
 477                 int ret_recv;
 478
 479                 /* First send a status message before receiving the fds. */
 480                 ret = consumer_send_status_msg(sock, ret_code);
 481                 if (ret < 0) {
 482                         /* Somehow, the session daemon is not responding anymore. */
 483                         goto error_fatal;
 484                 }
 485                 DBG("consumer_add_channel %" PRIu64, msg.u.channel.channel_key);
 486                 new_channel = consumer_allocate_channel(msg.u.channel.channel_key,
 487                                 msg.u.channel.session_id, msg.u.channel.pathname,
 488                                 msg.u.channel.name, msg.u.channel.uid, msg.u.channel.gid,
 489                                 msg.u.channel.relayd_id, msg.u.channel.output,
 490                                 msg.u.channel.tracefile_size,
 491                                 msg.u.channel.tracefile_count, 0,
 492                                 msg.u.channel.monitor);
 493                 if (new_channel == NULL) {
 494                         lttng_consumer_send_error(ctx, LTTCOMM_CONSUMERD_OUTFD_ERROR);
 495                         goto end_nosignal;
 496                 }
 497                 new_channel->nb_init_stream_left = msg.u.channel.nb_init_streams;
 498                 switch (msg.u.channel.output) {
 499                 case LTTNG_EVENT_SPLICE:
 500                         new_channel->output = CONSUMER_CHANNEL_SPLICE;
 501                         break;
 502                 case LTTNG_EVENT_MMAP:
 503                         new_channel->output = CONSUMER_CHANNEL_MMAP;
 504                         break;
 505                 default:
 506                         ERR("Channel output unknown %d", msg.u.channel.output);
 507                         goto end_nosignal;
 508                 }
 509
 510                 /* Translate and save channel type. */
 511                 switch (msg.u.channel.type) {
 512                 case CONSUMER_CHANNEL_TYPE_DATA:
 513                 case CONSUMER_CHANNEL_TYPE_METADATA:
 514                         new_channel->type = msg.u.channel.type;
 515                         break;
 516                 default:
 517                         assert(0);
 518                         goto end_nosignal;
 519                 };
 520
 521                 if (ctx->on_recv_channel != NULL) {
 522                         ret_recv = ctx->on_recv_channel(new_channel);
 523                         if (ret_recv == 0) {
 524                                 ret = consumer_add_channel(new_channel, ctx);
 525                         } else if (ret_recv < 0) {
 526                                 goto end_nosignal;
 527                         }
 528                 } else {
 529                         ret = consumer_add_channel(new_channel, ctx);
 530                 }
 531
 532                 /* If we received an error in add_channel, we need to report it. */
 533                 if (ret < 0) {
 534                         ret = consumer_send_status_msg(sock, ret);
 535                         if (ret < 0) {
 536                                 goto error_fatal;
 537                         }
 538                         goto end_nosignal;
 539                 }
 540
 541                 goto end_nosignal;
 542         }
 543         case LTTNG_CONSUMER_ADD_STREAM:
 544         {
 545                 int fd;
 546                 struct lttng_pipe *stream_pipe;
 547                 struct lttng_consumer_stream *new_stream;
 548                 struct lttng_consumer_channel *channel;
 549                 int alloc_ret = 0;
 550
 551                 /*
 552                  * Get stream's channel reference. Needed when adding the stream to the
 553                  * global hash table.
 554                  */
 555                 channel = consumer_find_channel(msg.u.stream.channel_key);
 556                 if (!channel) {
 557                         /*
 558                          * We could not find the channel. Can happen if cpu hotplug
 559                          * happens while tearing down.
 560                          */
 561                         ERR("Unable to find channel key %" PRIu64, msg.u.stream.channel_key);
 562                         ret_code = LTTNG_ERR_KERN_CHAN_NOT_FOUND;
 563                 }
 564
 565                 /* First send a status message before receiving the fds. */
 566                 ret = consumer_send_status_msg(sock, ret_code);
 567                 if (ret < 0) {
 568                         /*
 569                          * Somehow, the session daemon is not responding
 570                          * anymore.
 571                          */
 572                         goto error_fatal;
 573                 }
 574                 if (ret_code != LTTNG_OK) {
 575                         /*
 576                          * Channel was not found.
 577                          */
 578                         goto end_nosignal;
 579                 }
 580
 581                 /* block */
 582                 if (lttng_consumer_poll_socket(consumer_sockpoll) < 0) {
 583                         rcu_read_unlock();
 584                         return -EINTR;
 585                 }
 586
 587                 /* Get stream file descriptor from socket */
 588                 ret = lttcomm_recv_fds_unix_sock(sock, &fd, 1);
 589                 if (ret != sizeof(fd)) {
 590                         lttng_consumer_send_error(ctx, LTTCOMM_CONSUMERD_ERROR_RECV_FD);
 591                         rcu_read_unlock();
 592                         return ret;
 593                 }
 594
 595                 /*
 596                  * Send status code to session daemon only if the recv works. If the
 597                  * above recv() failed, the session daemon is notified through the
 598                  * error socket and the teardown is eventually done.
 599                  */
 600                 ret = consumer_send_status_msg(sock, ret_code);
 601                 if (ret < 0) {
 602                         /* Somehow, the session daemon is not responding anymore. */
 603                         goto end_nosignal;
 604                 }
 605
 606                 new_stream = consumer_allocate_stream(channel->key,
 607                                 fd,
 608                                 LTTNG_CONSUMER_ACTIVE_STREAM,
 609                                 channel->name,
 610                                 channel->uid,
 611                                 channel->gid,
 612                                 channel->relayd_id,
 613                                 channel->session_id,
 614                                 msg.u.stream.cpu,
 615                                 &alloc_ret,
 616                                 channel->type);
 617                 if (new_stream == NULL) {
 618                         switch (alloc_ret) {
 619                         case -ENOMEM:
 620                         case -EINVAL:
 621                         default:
 622                                 lttng_consumer_send_error(ctx, LTTCOMM_CONSUMERD_OUTFD_ERROR);
 623                                 break;
 624                         }
 625                         goto end_nosignal;
 626                 }
 627                 new_stream->chan = channel;
 628                 new_stream->wait_fd = fd;
 629                 switch (channel->output) {
 630                 case CONSUMER_CHANNEL_SPLICE:
 631                         new_stream->output = LTTNG_EVENT_SPLICE;
 632                         break;
 633                 case CONSUMER_CHANNEL_MMAP:
 634                         new_stream->output = LTTNG_EVENT_MMAP;
 635                         break;
 636                 default:
 637                         ERR("Stream output unknown %d", channel->output);
 638                         goto end_nosignal;
 639                 }
 640
 641                 /*
 642                  * We've just assigned the channel to the stream so increment the
 643                  * refcount right now. We don't need to increment the refcount for
 644                  * streams in no monitor because we handle manually the cleanup of
 645                  * those. It is very important to make sure there is NO prior
 646                  * consumer_del_stream() calls or else the refcount will be unbalanced.
 647                  */
 648                 if (channel->monitor) {
 649                         uatomic_inc(&new_stream->chan->refcount);
 650                 }
 651
 652                 /*
 653                  * The buffer flush is done on the session daemon side for the kernel
 654                  * so no need for the stream "hangup_flush_done" variable to be
 655                  * tracked. This is important for a kernel stream since we don't rely
 656                  * on the flush state of the stream to read data. It's not the case for
 657                  * user space tracing.
 658                  */
 659                 new_stream->hangup_flush_done = 0;
 660
 661                 if (ctx->on_recv_stream) {
 662                         ret = ctx->on_recv_stream(new_stream);
 663                         if (ret < 0) {
 664                                 consumer_del_stream(new_stream, NULL);
 665                                 goto end_nosignal;
 666                         }
 667                 }
 668
 669                 if (new_stream->metadata_flag) {
 670                         channel->metadata_stream = new_stream;
 671                 }
 672
 673                 /* Do not monitor this stream. */
 674                 if (!channel->monitor) {
 675                         DBG("Kernel consumer add stream %s in no monitor mode with "
 676                                         "relayd id %" PRIu64, new_stream->name,
 677                                         new_stream->net_seq_idx);
 678                         cds_list_add(&new_stream->no_monitor_node,
 679                                         &channel->stream_no_monitor_list.head);
 680                         break;
 681                 }
 682
 683                 ret = send_relayd_stream(new_stream, NULL);
 684                 if (ret < 0) {
 685                         consumer_del_stream(new_stream, NULL);
 686                         goto end_nosignal;
 687                 }
 688
 689                 /* Get the right pipe where the stream will be sent. */
 690                 if (new_stream->metadata_flag) {
 691                         stream_pipe = ctx->consumer_metadata_pipe;
 692                 } else {
 693                         stream_pipe = ctx->consumer_data_pipe;
 694                 }
 695
 696                 ret = lttng_pipe_write(stream_pipe, &new_stream, sizeof(new_stream));
 697                 if (ret < 0) {
 698                         ERR("Consumer write %s stream to pipe %d",
 699                                         new_stream->metadata_flag ? "metadata" : "data",
 700                                         lttng_pipe_get_writefd(stream_pipe));
 701                         consumer_del_stream(new_stream, NULL);
 702                         goto end_nosignal;
 703                 }
 704
 705                 DBG("Kernel consumer ADD_STREAM %s (fd: %d) with relayd id %" PRIu64,
 706                                 new_stream->name, fd, new_stream->relayd_stream_id);
 707                 break;
 708         }
 709         case LTTNG_CONSUMER_UPDATE_STREAM:
 710         {
 711                 rcu_read_unlock();
 712                 return -ENOSYS;
 713         }
 714         case LTTNG_CONSUMER_DESTROY_RELAYD:
 715         {
 716                 uint64_t index = msg.u.destroy_relayd.net_seq_idx;
 717                 struct consumer_relayd_sock_pair *relayd;
 718
 719                 DBG("Kernel consumer destroying relayd %" PRIu64, index);
 720
 721                 /* Get relayd reference if exists. */
 722                 relayd = consumer_find_relayd(index);
 723                 if (relayd == NULL) {
 724                         DBG("Unable to find relayd %" PRIu64, index);
 725                         ret_code = LTTNG_ERR_NO_CONSUMER;
 726                 }
 727
 728                 /*
 729                  * Each relayd socket pair has a refcount of stream attached to it
 730                  * which tells if the relayd is still active or not depending on the
 731                  * refcount value.
 732                  *
 733                  * This will set the destroy flag of the relayd object and destroy it
 734                  * if the refcount reaches zero when called.
 735                  *
 736                  * The destroy can happen either here or when a stream fd hangs up.
 737                  */
 738                 if (relayd) {
 739                         consumer_flag_relayd_for_destroy(relayd);
 740                 }
 741
 742                 ret = consumer_send_status_msg(sock, ret_code);
 743                 if (ret < 0) {
 744                         /* Somehow, the session daemon is not responding anymore. */
 745                         goto error_fatal;
 746                 }
 747
 748                 goto end_nosignal;
 749         }
 750         case LTTNG_CONSUMER_DATA_PENDING:
 751         {
 752                 int32_t ret;
 753                 uint64_t id = msg.u.data_pending.session_id;
 754
 755                 DBG("Kernel consumer data pending command for id %" PRIu64, id);
 756
 757                 ret = consumer_data_pending(id);
 758
 759                 /* Send back returned value to session daemon */
 760                 ret = lttcomm_send_unix_sock(sock, &ret, sizeof(ret));
 761                 if (ret < 0) {
 762                         PERROR("send data pending ret code");
 763                         goto error_fatal;
 764                 }
 765
 766                 /*
 767                  * No need to send back a status message since the data pending
 768                  * returned value is the response.
 769                  */
 770                 break;
 771         }
 772         case LTTNG_CONSUMER_SNAPSHOT_CHANNEL:
 773         {
 774                 if (msg.u.snapshot_channel.metadata == 1) {
 775                         ret = lttng_kconsumer_snapshot_metadata(msg.u.snapshot_channel.key,
 776                                         msg.u.snapshot_channel.pathname,
 777                                         msg.u.snapshot_channel.relayd_id, ctx);
 778                         if (ret < 0) {
 779                                 ERR("Snapshot metadata failed");
 780                                 ret_code = LTTNG_ERR_KERN_META_FAIL;
 781                         }
 782                 } else {
 783                         ret = lttng_kconsumer_snapshot_channel(msg.u.snapshot_channel.key,
 784                                         msg.u.snapshot_channel.pathname,
 785                                         msg.u.snapshot_channel.relayd_id, ctx);
 786                         if (ret < 0) {
 787                                 ERR("Snapshot channel failed");
 788                                 ret_code = LTTNG_ERR_KERN_CHAN_FAIL;
 789                         }
 790                 }
 791
 792                 ret = consumer_send_status_msg(sock, ret_code);
 793                 if (ret < 0) {
 794                         /* Somehow, the session daemon is not responding anymore. */
 795                         goto end_nosignal;
 796                 }
 797                 break;
 798         }
 799         case LTTNG_CONSUMER_DESTROY_CHANNEL:
 800         {
 801                 uint64_t key = msg.u.destroy_channel.key;
 802                 struct lttng_consumer_channel *channel;
 803
 804                 channel = consumer_find_channel(key);
 805                 if (!channel) {
 806                         ERR("Kernel consumer destroy channel %" PRIu64 " not found", key);
 807                         ret_code = LTTNG_ERR_KERN_CHAN_NOT_FOUND;
 808                 }
 809
 810                 ret = consumer_send_status_msg(sock, ret_code);
 811                 if (ret < 0) {
 812                         /* Somehow, the session daemon is not responding anymore. */
 813                         goto end_nosignal;
 814                 }
 815
 816                 /*
 817                  * This command should ONLY be issued for channel with streams set in
 818                  * no monitor mode.
 819                  */
 820                 assert(!channel->monitor);
 821
 822                 /*
 823                  * The refcount should ALWAYS be 0 in the case of a channel in no
 824                  * monitor mode.
 825                  */
 826                 assert(!uatomic_sub_return(&channel->refcount, 1));
 827
 828                 consumer_del_channel(channel);
 829
 830                 goto end_nosignal;
 831         }
 832         default:
 833                 goto end_nosignal;
 834         }
 835
 836 end_nosignal:
 837         rcu_read_unlock();
 838
 839         /*
 840          * Return 1 to indicate success since the 0 value can be a socket
 841          * shutdown during the recv() or send() call.
 842          */
 843         return 1;
 844
 845 error_fatal:
 846         rcu_read_unlock();
 847         /* This will issue a consumer stop. */
 848         return -1;
 849 }
 850
 851 /*
 852  * Consume data on a file descriptor and write it on a trace file.
 853  */
 854 ssize_t lttng_kconsumer_read_subbuffer(struct lttng_consumer_stream *stream,
 855                 struct lttng_consumer_local_data *ctx)
 856 {
 857         unsigned long len, subbuf_size, padding;
 858         int err;
 859         ssize_t ret = 0;
 860         int infd = stream->wait_fd;
 861
 862         DBG("In read_subbuffer (infd : %d)", infd);
 863         /* Get the next subbuffer */
 864         err = kernctl_get_next_subbuf(infd);
 865         if (err != 0) {
 866                 ret = err;
 867                 /*
 868                  * This is a debug message even for single-threaded consumer,
 869                  * because poll() have more relaxed criterions than get subbuf,
 870                  * so get_subbuf may fail for short race windows where poll()
 871                  * would issue wakeups.
 872                  */
 873                 DBG("Reserving sub buffer failed (everything is normal, "
 874                                 "it is due to concurrency)");
 875                 goto end;
 876         }
 877
 878         /* Get the full subbuffer size including padding */
 879         err = kernctl_get_padded_subbuf_size(infd, &len);
 880         if (err != 0) {
 881                 errno = -err;
 882                 perror("Getting sub-buffer len failed.");
 883                 ret = err;
 884                 goto end;
 885         }
 886
 887         switch (stream->chan->output) {
 888         case CONSUMER_CHANNEL_SPLICE:
 889                 /*
 890                  * XXX: The lttng-modules splice "actor" does not handle copying
 891                  * partial pages hence only using the subbuffer size without the
 892                  * padding makes the splice fail.
 893                  */
 894                 subbuf_size = len;
 895                 padding = 0;
 896
 897                 /* splice the subbuffer to the tracefile */
 898                 ret = lttng_consumer_on_read_subbuffer_splice(ctx, stream, subbuf_size,
 899                                 padding);
 900                 /*
 901                  * XXX: Splice does not support network streaming so the return value
 902                  * is simply checked against subbuf_size and not like the mmap() op.
 903                  */
 904                 if (ret != subbuf_size) {
 905                         /*
 906                          * display the error but continue processing to try
 907                          * to release the subbuffer
 908                          */
 909                         ERR("Error splicing to tracefile (ret: %zd != len: %lu)",
 910                                         ret, subbuf_size);
 911                 }
 912                 break;
 913         case CONSUMER_CHANNEL_MMAP:
 914                 /* Get subbuffer size without padding */
 915                 err = kernctl_get_subbuf_size(infd, &subbuf_size);
 916                 if (err != 0) {
 917                         errno = -err;
 918                         perror("Getting sub-buffer len failed.");
 919                         ret = err;
 920                         goto end;
 921                 }
 922
 923                 /* Make sure the tracer is not gone mad on us! */
 924                 assert(len >= subbuf_size);
 925
 926                 padding = len - subbuf_size;
 927
 928                 /* write the subbuffer to the tracefile */
 929                 ret = lttng_consumer_on_read_subbuffer_mmap(ctx, stream, subbuf_size,
 930                                 padding);
 931                 /*
 932                  * The mmap operation should write subbuf_size amount of data when
 933                  * network streaming or the full padding (len) size when we are _not_
 934                  * streaming.
 935                  */
 936                 if ((ret != subbuf_size && stream->net_seq_idx != (uint64_t) -1ULL) ||
 937                                 (ret != len && stream->net_seq_idx == (uint64_t) -1ULL)) {
 938                         /*
 939                          * Display the error but continue processing to try to release the
 940                          * subbuffer
 941                          */
 942                         ERR("Error writing to tracefile "
 943                                         "(ret: %zd != len: %lu != subbuf_size: %lu)",
 944                                         ret, len, subbuf_size);
 945                 }
 946                 break;
 947         default:
 948                 ERR("Unknown output method");
 949                 ret = -1;
 950         }
 951
 952         err = kernctl_put_next_subbuf(infd);
 953         if (err != 0) {
 954                 errno = -err;
 955                 if (errno == EFAULT) {
 956                         perror("Error in unreserving sub buffer\n");
 957                 } else if (errno == EIO) {
 958                         /* Should never happen with newer LTTng versions */
 959                         perror("Reader has been pushed by the writer, last sub-buffer corrupted.");
 960                 }
 961
 962                 ret = -err;
 963                 goto end;
 964         }
 965
 966 end:
 967         return ret;
 968 }
 969
 970 int lttng_kconsumer_on_recv_stream(struct lttng_consumer_stream *stream)
 971 {
 972         int ret;
 973
 974         assert(stream);
 975
 976         /*
 977          * Don't create anything if this is set for streaming or should not be
 978          * monitored.
 979          */
 980         if (stream->net_seq_idx == (uint64_t) -1ULL && stream->chan->monitor) {
 981                 ret = utils_create_stream_file(stream->chan->pathname, stream->name,
 982                                 stream->chan->tracefile_size, stream->tracefile_count_current,
 983                                 stream->uid, stream->gid);
 984                 if (ret < 0) {
 985                         goto error;
 986                 }
 987                 stream->out_fd = ret;
 988                 stream->tracefile_size_current = 0;
 989         }
 990
 991         if (stream->output == LTTNG_EVENT_MMAP) {
 992                 /* get the len of the mmap region */
 993                 unsigned long mmap_len;
 994
 995                 ret = kernctl_get_mmap_len(stream->wait_fd, &mmap_len);
 996                 if (ret != 0) {
 997                         errno = -ret;
 998                         PERROR("kernctl_get_mmap_len");
 999                         goto error_close_fd;
1000                 }
1001                 stream->mmap_len = (size_t) mmap_len;
1002
1003                 stream->mmap_base = mmap(NULL, stream->mmap_len, PROT_READ,
1004                                 MAP_PRIVATE, stream->wait_fd, 0);
1005                 if (stream->mmap_base == MAP_FAILED) {
1006                         PERROR("Error mmaping");
1007                         ret = -1;
1008                         goto error_close_fd;
1009                 }
1010         }
1011
1012         /* we return 0 to let the library handle the FD internally */
1013         return 0;
1014
1015 error_close_fd:
1016         {
1017                 int err;
1018
1019                 err = close(stream->out_fd);
1020                 assert(!err);
1021         }
1022 error:
1023         return ret;
1024 }
1025
1026 /*
1027  * Check if data is still being extracted from the buffers for a specific
1028  * stream. Consumer data lock MUST be acquired before calling this function
1029  * and the stream lock.
1030  *
1031  * Return 1 if the traced data are still getting read else 0 meaning that the
1032  * data is available for trace viewer reading.
1033  */
1034 int lttng_kconsumer_data_pending(struct lttng_consumer_stream *stream)
1035 {
1036         int ret;
1037
1038         assert(stream);
1039
1040         ret = kernctl_get_next_subbuf(stream->wait_fd);
1041         if (ret == 0) {
1042                 /* There is still data so let's put back this subbuffer. */
1043                 ret = kernctl_put_subbuf(stream->wait_fd);
1044                 assert(ret == 0);
1045                 ret = 1;   /* Data is pending */
1046                 goto end;
1047         }
1048
1049         /* Data is NOT pending and ready to be read. */
1050         ret = 0;
1051
1052 end:
1053         return ret;
1054 }