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