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