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