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, 0,
 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                 switch (msg.u.channel.output) {
 491                 case LTTNG_EVENT_SPLICE:
 492                         new_channel->output = CONSUMER_CHANNEL_SPLICE;
 493                         break;
 494                 case LTTNG_EVENT_MMAP:
 495                         new_channel->output = CONSUMER_CHANNEL_MMAP;
 496                         break;
 497                 default:
 498                         ERR("Channel output unknown %d", msg.u.channel.output);
 499                         goto end_nosignal;
 500                 }
 501
 502                 /* Translate and save channel type. */
 503                 switch (msg.u.channel.type) {
 504                 case CONSUMER_CHANNEL_TYPE_DATA:
 505                 case CONSUMER_CHANNEL_TYPE_METADATA:
 506                         new_channel->type = msg.u.channel.type;
 507                         break;
 508                 default:
 509                         assert(0);
 510                         goto end_nosignal;
 511                 };
 512
 513                 if (ctx->on_recv_channel != NULL) {
 514                         ret_recv = ctx->on_recv_channel(new_channel);
 515                         if (ret_recv == 0) {
 516                                 ret = consumer_add_channel(new_channel, ctx);
 517                         } else if (ret_recv < 0) {
 518                                 goto end_nosignal;
 519                         }
 520                 } else {
 521                         ret = consumer_add_channel(new_channel, ctx);
 522                 }
 523
 524                 /* If we received an error in add_channel, we need to report it. */
 525                 if (ret < 0) {
 526                         ret = consumer_send_status_msg(sock, ret);
 527                         if (ret < 0) {
 528                                 goto error_fatal;
 529                         }
 530                         goto end_nosignal;
 531                 }
 532
 533                 goto end_nosignal;
 534         }
 535         case LTTNG_CONSUMER_ADD_STREAM:
 536         {
 537                 int fd;
 538                 struct lttng_pipe *stream_pipe;
 539                 struct lttng_consumer_stream *new_stream;
 540                 struct lttng_consumer_channel *channel;
 541                 int alloc_ret = 0;
 542
 543                 /*
 544                  * Get stream's channel reference. Needed when adding the stream to the
 545                  * global hash table.
 546                  */
 547                 channel = consumer_find_channel(msg.u.stream.channel_key);
 548                 if (!channel) {
 549                         /*
 550                          * We could not find the channel. Can happen if cpu hotplug
 551                          * happens while tearing down.
 552                          */
 553                         ERR("Unable to find channel key %" PRIu64, msg.u.stream.channel_key);
 554                         ret_code = LTTNG_ERR_KERN_CHAN_NOT_FOUND;
 555                 }
 556
 557                 /* First send a status message before receiving the fds. */
 558                 ret = consumer_send_status_msg(sock, ret_code);
 559                 if (ret < 0) {
 560                         /*
 561                          * Somehow, the session daemon is not responding
 562                          * anymore.
 563                          */
 564                         goto error_fatal;
 565                 }
 566                 if (ret_code != LTTNG_OK) {
 567                         /*
 568                          * Channel was not found.
 569                          */
 570                         goto end_nosignal;
 571                 }
 572
 573                 /* block */
 574                 if (lttng_consumer_poll_socket(consumer_sockpoll) < 0) {
 575                         rcu_read_unlock();
 576                         return -EINTR;
 577                 }
 578
 579                 /* Get stream file descriptor from socket */
 580                 ret = lttcomm_recv_fds_unix_sock(sock, &fd, 1);
 581                 if (ret != sizeof(fd)) {
 582                         lttng_consumer_send_error(ctx, LTTCOMM_CONSUMERD_ERROR_RECV_FD);
 583                         rcu_read_unlock();
 584                         return ret;
 585                 }
 586
 587                 /*
 588                  * Send status code to session daemon only if the recv works. If the
 589                  * above recv() failed, the session daemon is notified through the
 590                  * error socket and the teardown is eventually done.
 591                  */
 592                 ret = consumer_send_status_msg(sock, ret_code);
 593                 if (ret < 0) {
 594                         /* Somehow, the session daemon is not responding anymore. */
 595                         goto end_nosignal;
 596                 }
 597
 598                 new_stream = consumer_allocate_stream(channel->key,
 599                                 fd,
 600                                 LTTNG_CONSUMER_ACTIVE_STREAM,
 601                                 channel->name,
 602                                 channel->uid,
 603                                 channel->gid,
 604                                 channel->relayd_id,
 605                                 channel->session_id,
 606                                 msg.u.stream.cpu,
 607                                 &alloc_ret,
 608                                 channel->type);
 609                 if (new_stream == NULL) {
 610                         switch (alloc_ret) {
 611                         case -ENOMEM:
 612                         case -EINVAL:
 613                         default:
 614                                 lttng_consumer_send_error(ctx, LTTCOMM_CONSUMERD_OUTFD_ERROR);
 615                                 break;
 616                         }
 617                         goto end_nosignal;
 618                 }
 619                 new_stream->chan = channel;
 620                 new_stream->wait_fd = fd;
 621                 switch (channel->output) {
 622                 case CONSUMER_CHANNEL_SPLICE:
 623                         new_stream->output = LTTNG_EVENT_SPLICE;
 624                         break;
 625                 case CONSUMER_CHANNEL_MMAP:
 626                         new_stream->output = LTTNG_EVENT_MMAP;
 627                         break;
 628                 default:
 629                         ERR("Stream output unknown %d", channel->output);
 630                         goto end_nosignal;
 631                 }
 632
 633                 /*
 634                  * We've just assigned the channel to the stream so increment the
 635                  * refcount right now. We don't need to increment the refcount for
 636                  * streams in no monitor because we handle manually the cleanup of
 637                  * those. It is very important to make sure there is NO prior
 638                  * consumer_del_stream() calls or else the refcount will be unbalanced.
 639                  */
 640                 if (channel->monitor) {
 641                         uatomic_inc(&new_stream->chan->refcount);
 642                 }
 643
 644                 /*
 645                  * The buffer flush is done on the session daemon side for the kernel
 646                  * so no need for the stream "hangup_flush_done" variable to be
 647                  * tracked. This is important for a kernel stream since we don't rely
 648                  * on the flush state of the stream to read data. It's not the case for
 649                  * user space tracing.
 650                  */
 651                 new_stream->hangup_flush_done = 0;
 652
 653                 if (ctx->on_recv_stream) {
 654                         ret = ctx->on_recv_stream(new_stream);
 655                         if (ret < 0) {
 656                                 consumer_del_stream(new_stream, NULL);
 657                                 goto end_nosignal;
 658                         }
 659                 }
 660
 661                 if (new_stream->metadata_flag) {
 662                         channel->metadata_stream = new_stream;
 663                 }
 664
 665                 /* Do not monitor this stream. */
 666                 if (!channel->monitor) {
 667                         DBG("Kernel consumer add stream %s in no monitor mode with"
 668                                         "relayd id %" PRIu64, new_stream->name,
 669                                         new_stream->relayd_stream_id);
 670                         cds_list_add(&new_stream->no_monitor_node,
 671                                         &channel->stream_no_monitor_list.head);
 672                         break;
 673                 }
 674
 675                 ret = send_relayd_stream(new_stream, NULL);
 676                 if (ret < 0) {
 677                         consumer_del_stream(new_stream, NULL);
 678                         goto end_nosignal;
 679                 }
 680
 681                 /* Get the right pipe where the stream will be sent. */
 682                 if (new_stream->metadata_flag) {
 683                         stream_pipe = ctx->consumer_metadata_pipe;
 684                 } else {
 685                         stream_pipe = ctx->consumer_data_pipe;
 686                 }
 687
 688                 ret = lttng_pipe_write(stream_pipe, &new_stream, sizeof(new_stream));
 689                 if (ret < 0) {
 690                         ERR("Consumer write %s stream to pipe %d",
 691                                         new_stream->metadata_flag ? "metadata" : "data",
 692                                         lttng_pipe_get_writefd(stream_pipe));
 693                         consumer_del_stream(new_stream, NULL);
 694                         goto end_nosignal;
 695                 }
 696
 697                 DBG("Kernel consumer ADD_STREAM %s (fd: %d) with relayd id %" PRIu64,
 698                                 new_stream->name, fd, new_stream->relayd_stream_id);
 699                 break;
 700         }
 701         case LTTNG_CONSUMER_UPDATE_STREAM:
 702         {
 703                 rcu_read_unlock();
 704                 return -ENOSYS;
 705         }
 706         case LTTNG_CONSUMER_DESTROY_RELAYD:
 707         {
 708                 uint64_t index = msg.u.destroy_relayd.net_seq_idx;
 709                 struct consumer_relayd_sock_pair *relayd;
 710
 711                 DBG("Kernel consumer destroying relayd %" PRIu64, index);
 712
 713                 /* Get relayd reference if exists. */
 714                 relayd = consumer_find_relayd(index);
 715                 if (relayd == NULL) {
 716                         DBG("Unable to find relayd %" PRIu64, index);
 717                         ret_code = LTTNG_ERR_NO_CONSUMER;
 718                 }
 719
 720                 /*
 721                  * Each relayd socket pair has a refcount of stream attached to it
 722                  * which tells if the relayd is still active or not depending on the
 723                  * refcount value.
 724                  *
 725                  * This will set the destroy flag of the relayd object and destroy it
 726                  * if the refcount reaches zero when called.
 727                  *
 728                  * The destroy can happen either here or when a stream fd hangs up.
 729                  */
 730                 if (relayd) {
 731                         consumer_flag_relayd_for_destroy(relayd);
 732                 }
 733
 734                 ret = consumer_send_status_msg(sock, ret_code);
 735                 if (ret < 0) {
 736                         /* Somehow, the session daemon is not responding anymore. */
 737                         goto error_fatal;
 738                 }
 739
 740                 goto end_nosignal;
 741         }
 742         case LTTNG_CONSUMER_DATA_PENDING:
 743         {
 744                 int32_t ret;
 745                 uint64_t id = msg.u.data_pending.session_id;
 746
 747                 DBG("Kernel consumer data pending command for id %" PRIu64, id);
 748
 749                 ret = consumer_data_pending(id);
 750
 751                 /* Send back returned value to session daemon */
 752                 ret = lttcomm_send_unix_sock(sock, &ret, sizeof(ret));
 753                 if (ret < 0) {
 754                         PERROR("send data pending ret code");
 755                         goto error_fatal;
 756                 }
 757
 758                 /*
 759                  * No need to send back a status message since the data pending
 760                  * returned value is the response.
 761                  */
 762                 break;
 763         }
 764         case LTTNG_CONSUMER_SNAPSHOT_CHANNEL:
 765         {
 766                 if (msg.u.snapshot_channel.metadata == 1) {
 767                         ret = lttng_kconsumer_snapshot_metadata(msg.u.snapshot_channel.key,
 768                                         msg.u.snapshot_channel.pathname,
 769                                         msg.u.snapshot_channel.relayd_id, ctx);
 770                         if (ret < 0) {
 771                                 ERR("Snapshot metadata failed");
 772                                 ret_code = LTTNG_ERR_KERN_META_FAIL;
 773                         }
 774                 } else {
 775                         ret = lttng_kconsumer_snapshot_channel(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 channel failed");
 780                                 ret_code = LTTNG_ERR_KERN_CHAN_FAIL;
 781                         }
 782                 }
 783
 784                 ret = consumer_send_status_msg(sock, ret_code);
 785                 if (ret < 0) {
 786                         /* Somehow, the session daemon is not responding anymore. */
 787                         goto end_nosignal;
 788                 }
 789                 break;
 790         }
 791         case LTTNG_CONSUMER_DESTROY_CHANNEL:
 792         {
 793                 uint64_t key = msg.u.destroy_channel.key;
 794                 struct lttng_consumer_channel *channel;
 795
 796                 channel = consumer_find_channel(key);
 797                 if (!channel) {
 798                         ERR("Kernel consumer destroy channel %" PRIu64 " not found", key);
 799                         ret_code = LTTNG_ERR_KERN_CHAN_NOT_FOUND;
 800                 }
 801
 802                 ret = consumer_send_status_msg(sock, ret_code);
 803                 if (ret < 0) {
 804                         /* Somehow, the session daemon is not responding anymore. */
 805                         goto end_nosignal;
 806                 }
 807
 808                 /*
 809                  * This command should ONLY be issued for channel with streams set in
 810                  * no monitor mode.
 811                  */
 812                 assert(!channel->monitor);
 813
 814                 /*
 815                  * The refcount should ALWAYS be 0 in the case of a channel in no
 816                  * monitor mode.
 817                  */
 818                 assert(!uatomic_sub_return(&channel->refcount, 1));
 819
 820                 consumer_del_channel(channel);
 821
 822                 goto end_nosignal;
 823         }
 824         default:
 825                 goto end_nosignal;
 826         }
 827
 828 end_nosignal:
 829         rcu_read_unlock();
 830
 831         /*
 832          * Return 1 to indicate success since the 0 value can be a socket
 833          * shutdown during the recv() or send() call.
 834          */
 835         return 1;
 836
 837 error_fatal:
 838         rcu_read_unlock();
 839         /* This will issue a consumer stop. */
 840         return -1;
 841 }
 842
 843 /*
 844  * Consume data on a file descriptor and write it on a trace file.
 845  */
 846 ssize_t lttng_kconsumer_read_subbuffer(struct lttng_consumer_stream *stream,
 847                 struct lttng_consumer_local_data *ctx)
 848 {
 849         unsigned long len, subbuf_size, padding;
 850         int err;
 851         ssize_t ret = 0;
 852         int infd = stream->wait_fd;
 853
 854         DBG("In read_subbuffer (infd : %d)", infd);
 855         /* Get the next subbuffer */
 856         err = kernctl_get_next_subbuf(infd);
 857         if (err != 0) {
 858                 ret = err;
 859                 /*
 860                  * This is a debug message even for single-threaded consumer,
 861                  * because poll() have more relaxed criterions than get subbuf,
 862                  * so get_subbuf may fail for short race windows where poll()
 863                  * would issue wakeups.
 864                  */
 865                 DBG("Reserving sub buffer failed (everything is normal, "
 866                                 "it is due to concurrency)");
 867                 goto end;
 868         }
 869
 870         /* Get the full subbuffer size including padding */
 871         err = kernctl_get_padded_subbuf_size(infd, &len);
 872         if (err != 0) {
 873                 errno = -err;
 874                 perror("Getting sub-buffer len failed.");
 875                 ret = err;
 876                 goto end;
 877         }
 878
 879         switch (stream->chan->output) {
 880         case CONSUMER_CHANNEL_SPLICE:
 881                 /*
 882                  * XXX: The lttng-modules splice "actor" does not handle copying
 883                  * partial pages hence only using the subbuffer size without the
 884                  * padding makes the splice fail.
 885                  */
 886                 subbuf_size = len;
 887                 padding = 0;
 888
 889                 /* splice the subbuffer to the tracefile */
 890                 ret = lttng_consumer_on_read_subbuffer_splice(ctx, stream, subbuf_size,
 891                                 padding);
 892                 /*
 893                  * XXX: Splice does not support network streaming so the return value
 894                  * is simply checked against subbuf_size and not like the mmap() op.
 895                  */
 896                 if (ret != subbuf_size) {
 897                         /*
 898                          * display the error but continue processing to try
 899                          * to release the subbuffer
 900                          */
 901                         ERR("Error splicing to tracefile (ret: %zd != len: %lu)",
 902                                         ret, subbuf_size);
 903                 }
 904                 break;
 905         case CONSUMER_CHANNEL_MMAP:
 906                 /* Get subbuffer size without padding */
 907                 err = kernctl_get_subbuf_size(infd, &subbuf_size);
 908                 if (err != 0) {
 909                         errno = -err;
 910                         perror("Getting sub-buffer len failed.");
 911                         ret = err;
 912                         goto end;
 913                 }
 914
 915                 /* Make sure the tracer is not gone mad on us! */
 916                 assert(len >= subbuf_size);
 917
 918                 padding = len - subbuf_size;
 919
 920                 /* write the subbuffer to the tracefile */
 921                 ret = lttng_consumer_on_read_subbuffer_mmap(ctx, stream, subbuf_size,
 922                                 padding);
 923                 /*
 924                  * The mmap operation should write subbuf_size amount of data when
 925                  * network streaming or the full padding (len) size when we are _not_
 926                  * streaming.
 927                  */
 928                 if ((ret != subbuf_size && stream->net_seq_idx != (uint64_t) -1ULL) ||
 929                                 (ret != len && stream->net_seq_idx == (uint64_t) -1ULL)) {
 930                         /*
 931                          * Display the error but continue processing to try to release the
 932                          * subbuffer
 933                          */
 934                         ERR("Error writing to tracefile "
 935                                         "(ret: %zd != len: %lu != subbuf_size: %lu)",
 936                                         ret, len, subbuf_size);
 937                 }
 938                 break;
 939         default:
 940                 ERR("Unknown output method");
 941                 ret = -1;
 942         }
 943
 944         err = kernctl_put_next_subbuf(infd);
 945         if (err != 0) {
 946                 errno = -err;
 947                 if (errno == EFAULT) {
 948                         perror("Error in unreserving sub buffer\n");
 949                 } else if (errno == EIO) {
 950                         /* Should never happen with newer LTTng versions */
 951                         perror("Reader has been pushed by the writer, last sub-buffer corrupted.");
 952                 }
 953
 954                 ret = -err;
 955                 goto end;
 956         }
 957
 958 end:
 959         return ret;
 960 }
 961
 962 int lttng_kconsumer_on_recv_stream(struct lttng_consumer_stream *stream)
 963 {
 964         int ret;
 965
 966         assert(stream);
 967
 968         /*
 969          * Don't create anything if this is set for streaming or should not be
 970          * monitored.
 971          */
 972         if (stream->net_seq_idx == (uint64_t) -1ULL && stream->chan->monitor) {
 973                 ret = utils_create_stream_file(stream->chan->pathname, stream->name,
 974                                 stream->chan->tracefile_size, stream->tracefile_count_current,
 975                                 stream->uid, stream->gid);
 976                 if (ret < 0) {
 977                         goto error;
 978                 }
 979                 stream->out_fd = ret;
 980                 stream->tracefile_size_current = 0;
 981         }
 982
 983         if (stream->output == LTTNG_EVENT_MMAP) {
 984                 /* get the len of the mmap region */
 985                 unsigned long mmap_len;
 986
 987                 ret = kernctl_get_mmap_len(stream->wait_fd, &mmap_len);
 988                 if (ret != 0) {
 989                         errno = -ret;
 990                         PERROR("kernctl_get_mmap_len");
 991                         goto error_close_fd;
 992                 }
 993                 stream->mmap_len = (size_t) mmap_len;
 994
 995                 stream->mmap_base = mmap(NULL, stream->mmap_len, PROT_READ,
 996                                 MAP_PRIVATE, stream->wait_fd, 0);
 997                 if (stream->mmap_base == MAP_FAILED) {
 998                         PERROR("Error mmaping");
 999                         ret = -1;
1000                         goto error_close_fd;
1001                 }
1002         }
1003
1004         /* we return 0 to let the library handle the FD internally */
1005         return 0;
1006
1007 error_close_fd:
1008         {
1009                 int err;
1010
1011                 err = close(stream->out_fd);
1012                 assert(!err);
1013         }
1014 error:
1015         return ret;
1016 }
1017
1018 /*
1019  * Check if data is still being extracted from the buffers for a specific
1020  * stream. Consumer data lock MUST be acquired before calling this function
1021  * and the stream lock.
1022  *
1023  * Return 1 if the traced data are still getting read else 0 meaning that the
1024  * data is available for trace viewer reading.
1025  */
1026 int lttng_kconsumer_data_pending(struct lttng_consumer_stream *stream)
1027 {
1028         int ret;
1029
1030         assert(stream);
1031
1032         ret = kernctl_get_next_subbuf(stream->wait_fd);
1033         if (ret == 0) {
1034                 /* There is still data so let's put back this subbuffer. */
1035                 ret = kernctl_put_subbuf(stream->wait_fd);
1036                 assert(ret == 0);
1037                 ret = 1;   /* Data is pending */
1038                 goto end;
1039         }
1040
1041         /* Data is NOT pending and ready to be read. */
1042         ret = 0;
1043
1044 end:
1045         return ret;
1046 }