src/common/kernel-consumer/kernel-consumer.c

   1 /*
   2  * Copyright (C) 2011 - Julien Desfossez <julien.desfossez@polymtl.ca>
   3  *                      Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License, version 2 only,
   7  * as published by the Free Software Foundation.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License along
  15  * with this program; if not, write to the Free Software Foundation, Inc.,
  16  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  17  */
  18
  19 #define _GNU_SOURCE
  20 #include <assert.h>
  21 #include <poll.h>
  22 #include <pthread.h>
  23 #include <stdlib.h>
  24 #include <string.h>
  25 #include <sys/mman.h>
  26 #include <sys/socket.h>
  27 #include <sys/types.h>
  28 #include <inttypes.h>
  29 #include <unistd.h>
  30 #include <sys/stat.h>
  31
  32 #include <common/common.h>
  33 #include <common/kernel-ctl/kernel-ctl.h>
  34 #include <common/sessiond-comm/sessiond-comm.h>
  35 #include <common/sessiond-comm/relayd.h>
  36 #include <common/compat/fcntl.h>
  37 #include <common/pipe.h>
  38 #include <common/relayd/relayd.h>
  39 #include <common/utils.h>
  40 #include <common/consumer-stream.h>
  41
  42 #include "kernel-consumer.h"
  43
  44 extern struct lttng_consumer_global_data consumer_data;
  45 extern int consumer_poll_timeout;
  46 extern volatile int consumer_quit;
  47
  48 /*
  49  * Take a snapshot for a specific fd
  50  *
  51  * Returns 0 on success, < 0 on error
  52  */
  53 int lttng_kconsumer_take_snapshot(struct lttng_consumer_stream *stream)
  54 {
  55         int ret = 0;
  56         int infd = stream->wait_fd;
  57
  58         ret = kernctl_snapshot(infd);
  59         if (ret != 0) {
  60                 errno = -ret;
  61                 perror("Getting sub-buffer snapshot.");
  62         }
  63
  64         return ret;
  65 }
  66
  67 /*
  68  * Get the produced position
  69  *
  70  * Returns 0 on success, < 0 on error
  71  */
  72 int lttng_kconsumer_get_produced_snapshot(struct lttng_consumer_stream *stream,
  73                 unsigned long *pos)
  74 {
  75         int ret;
  76         int infd = stream->wait_fd;
  77
  78         ret = kernctl_snapshot_get_produced(infd, pos);
  79         if (ret != 0) {
  80                 errno = -ret;
  81                 perror("kernctl_snapshot_get_produced");
  82         }
  83
  84         return ret;
  85 }
  86
  87 /*
  88  * Get the consumerd position
  89  *
  90  * Returns 0 on success, < 0 on error
  91  */
  92 int lttng_kconsumer_get_consumed_snapshot(struct lttng_consumer_stream *stream,
  93                 unsigned long *pos)
  94 {
  95         int ret;
  96         int infd = stream->wait_fd;
  97
  98         ret = kernctl_snapshot_get_consumed(infd, pos);
  99         if (ret != 0) {
 100                 errno = -ret;
 101                 perror("kernctl_snapshot_get_consumed");
 102         }
 103
 104         return ret;
 105 }
 106
 107 /*
 108  * Find a relayd and send the stream
 109  *
 110  * Returns 0 on success, < 0 on error
 111  */
 112 static
 113 int send_relayd_stream(struct lttng_consumer_stream *stream, char *path)
 114 {
 115         struct consumer_relayd_sock_pair *relayd;
 116         int ret = 0;
 117         char *stream_path;
 118
 119         if (path != NULL) {
 120                 stream_path = path;
 121         } else {
 122                 stream_path = stream->chan->pathname;
 123         }
 124         /* The stream is not metadata. Get relayd reference if exists. */
 125         rcu_read_lock();
 126         relayd = consumer_find_relayd(stream->net_seq_idx);
 127         if (relayd != NULL) {
 128                 /* Add stream on the relayd */
 129                 pthread_mutex_lock(&relayd->ctrl_sock_mutex);
 130                 ret = relayd_add_stream(&relayd->control_sock,
 131                                 stream->name, stream_path,
 132                                 &stream->relayd_stream_id,
 133                                 stream->chan->tracefile_size,
 134                                 stream->chan->tracefile_count);
 135                 pthread_mutex_unlock(&relayd->ctrl_sock_mutex);
 136                 if (ret < 0) {
 137                         goto end;
 138                 }
 139                 uatomic_inc(&relayd->refcount);
 140         } else if (stream->net_seq_idx != (uint64_t) -1ULL) {
 141                 ERR("Network sequence index %" PRIu64 " unknown. Not adding stream.",
 142                                 stream->net_seq_idx);
 143                 ret = -1;
 144                 goto end;
 145         }
 146
 147 end:
 148         rcu_read_unlock();
 149         return ret;
 150 }
 151
 152 /*
 153  * Find a relayd and close the stream
 154  */
 155 static
 156 void close_relayd_stream(struct lttng_consumer_stream *stream)
 157 {
 158         struct consumer_relayd_sock_pair *relayd;
 159
 160         /* The stream is not metadata. Get relayd reference if exists. */
 161         rcu_read_lock();
 162         relayd = consumer_find_relayd(stream->net_seq_idx);
 163         if (relayd != NULL) {
 164                 consumer_stream_relayd_close(stream, relayd);
 165         }
 166         rcu_read_unlock();
 167 }
 168
 169 /*
 170  * Take a snapshot of all the stream of a channel
 171  *
 172  * Returns 0 on success, < 0 on error
 173  */
 174 int lttng_kconsumer_snapshot_channel(uint64_t key, char *path,
 175                 uint64_t relayd_id, struct lttng_consumer_local_data *ctx)
 176 {
 177         int ret;
 178         unsigned long consumed_pos, produced_pos;
 179         struct lttng_consumer_channel *channel;
 180         struct lttng_consumer_stream *stream;
 181
 182         DBG("Kernel consumer snapshot channel %lu", key);
 183
 184         rcu_read_lock();
 185
 186         channel = consumer_find_channel(key);
 187         if (!channel) {
 188                 ERR("No channel found for key %lu", key);
 189                 ret = -1;
 190                 goto end;
 191         }
 192
 193         /* Splice is not supported yet for channel snapshot. */
 194         if (channel->output != CONSUMER_CHANNEL_MMAP) {
 195                 ERR("Unsupported output %d", channel->output);
 196                 ret = -1;
 197                 goto end;
 198         }
 199
 200         cds_list_for_each_entry(stream, &channel->stream_no_monitor_list.head,
 201                         no_monitor_node) {
 202                 /*
 203                  * Lock stream because we are about to change its state.
 204                  */
 205                 pthread_mutex_lock(&stream->lock);
 206
 207                 stream->net_seq_idx = relayd_id;
 208                 channel->relayd_id = relayd_id;
 209                 if (relayd_id != (uint64_t) -1ULL) {
 210                         ret = send_relayd_stream(stream, path);
 211                         if (ret < 0) {
 212                                 ERR("sending stream to relayd");
 213                                 goto end_unlock;
 214                         }
 215                         DBG("Stream %s sent to the relayd", stream->name);
 216                 } else {
 217                         ret = utils_create_stream_file(path, stream->name,
 218                                         stream->chan->tracefile_size, stream->tracefile_count_current,
 219                                         stream->uid, stream->gid);
 220                         if (ret < 0) {
 221                                 ERR("utils_create_stream_file");
 222                                 goto end_unlock;
 223                         }
 224
 225                         stream->out_fd = ret;
 226                         stream->tracefile_size_current = 0;
 227
 228                         DBG("Kernel consumer snapshot stream %s/%s (%lu)", path,
 229                                         stream->name, stream->key);
 230                 }
 231
 232                 ret = kernctl_buffer_flush(stream->wait_fd);
 233                 if (ret < 0) {
 234                         ERR("Failed to flush kernel metadata stream");
 235                         goto end_unlock;
 236                 }
 237
 238                 ret = lttng_kconsumer_take_snapshot(stream);
 239                 if (ret < 0) {
 240                         ERR("Taking kernel snapshot");
 241                         goto end_unlock;
 242                 }
 243
 244                 ret = lttng_kconsumer_get_produced_snapshot(stream, &produced_pos);
 245                 if (ret < 0) {
 246                         ERR("Produced kernel snapshot position");
 247                         goto end_unlock;
 248                 }
 249
 250                 ret = lttng_kconsumer_get_consumed_snapshot(stream, &consumed_pos);
 251                 if (ret < 0) {
 252                         ERR("Consumerd kernel snapshot position");
 253                         goto end_unlock;
 254                 }
 255
 256                 if (stream->max_sb_size == 0) {
 257                         ret = kernctl_get_max_subbuf_size(stream->wait_fd,
 258                                         &stream->max_sb_size);
 259                         if (ret < 0) {
 260                                 ERR("Getting kernel max_sb_size");
 261                                 goto end_unlock;
 262                         }
 263                 }
 264
 265                 while (consumed_pos < produced_pos) {
 266                         ssize_t read_len;
 267                         unsigned long len, padded_len;
 268
 269                         DBG("Kernel consumer taking snapshot at pos %lu", consumed_pos);
 270
 271                         ret = kernctl_get_subbuf(stream->wait_fd, &consumed_pos);
 272                         if (ret < 0) {
 273                                 if (errno != EAGAIN) {
 274                                         PERROR("kernctl_get_subbuf snapshot");
 275                                         goto end_unlock;
 276                                 }
 277                                 DBG("Kernel consumer get subbuf failed. Skipping it.");
 278                                 consumed_pos += stream->max_sb_size;
 279                                 continue;
 280                         }
 281
 282                         ret = kernctl_get_subbuf_size(stream->wait_fd, &len);
 283                         if (ret < 0) {
 284                                 ERR("Snapshot kernctl_get_subbuf_size");
 285                                 goto end_unlock;
 286                         }
 287
 288                         ret = kernctl_get_padded_subbuf_size(stream->wait_fd, &padded_len);
 289                         if (ret < 0) {
 290                                 ERR("Snapshot kernctl_get_padded_subbuf_size");
 291                                 goto end_unlock;
 292                         }
 293
 294                         read_len = lttng_consumer_on_read_subbuffer_mmap(ctx, stream, len,
 295                                         padded_len - len);
 296                         /*
 297                          * We write the padded len in local tracefiles but the
 298                          * data len when using a relay.
 299                          * Display the error but continue processing to try to
 300                          * release the subbuffer.
 301                          */
 302                         if (relayd_id != (uint64_t) -1ULL) {
 303                                 if (read_len != len) {
 304                                         ERR("Error sending to the relay (ret: %zd != len: %lu)",
 305                                                         read_len, len);
 306                                 }
 307                         } else {
 308                                 if (read_len != padded_len) {
 309                                         ERR("Error writing to tracefile (ret: %zd != len: %lu)",
 310                                                         read_len, padded_len);
 311                                 }
 312                         }
 313
 314                         ret = kernctl_put_subbuf(stream->wait_fd);
 315                         if (ret < 0) {
 316                                 ERR("Snapshot kernctl_put_subbuf");
 317                                 goto end_unlock;
 318                         }
 319                         consumed_pos += stream->max_sb_size;
 320                 }
 321
 322                 if (relayd_id == (uint64_t) -1ULL) {
 323                         ret = close(stream->out_fd);
 324                         if (ret < 0) {
 325                                 PERROR("Kernel consumer snapshot close out_fd");
 326                                 goto end_unlock;
 327                         }
 328                         stream->out_fd = -1;
 329                 } else {
 330                         close_relayd_stream(stream);
 331                         stream->net_seq_idx = (uint64_t) -1ULL;
 332                 }
 333                 pthread_mutex_unlock(&stream->lock);
 334         }
 335
 336         /* All good! */
 337         ret = 0;
 338         goto end;
 339
 340 end_unlock:
 341         pthread_mutex_unlock(&stream->lock);
 342 end:
 343         rcu_read_unlock();
 344         return ret;
 345 }
 346
 347 /*
 348  * Read the whole metadata available for a snapshot.
 349  *
 350  * Returns 0 on success, < 0 on error
 351  */
 352 int lttng_kconsumer_snapshot_metadata(uint64_t key, char *path,
 353                 struct lttng_consumer_local_data *ctx)
 354 {
 355         struct lttng_consumer_channel *metadata_channel;
 356         struct lttng_consumer_stream *metadata_stream;
 357         int ret;
 358
 359         DBG("Kernel consumer snapshot metadata with key %" PRIu64 " at path %s",
 360                         key, path);
 361
 362         rcu_read_lock();
 363
 364         metadata_channel = consumer_find_channel(key);
 365         if (!metadata_channel) {
 366                 ERR("Snapshot kernel metadata channel not found for key %lu", key);
 367                 ret = -1;
 368                 goto end;
 369         }
 370
 371         metadata_stream = metadata_channel->metadata_stream;
 372         assert(metadata_stream);
 373
 374         ret = utils_create_stream_file(path, metadata_stream->name,
 375                         metadata_stream->chan->tracefile_size,
 376                         metadata_stream->tracefile_count_current,
 377                         metadata_stream->uid, metadata_stream->gid);
 378         if (ret < 0) {
 379                 goto end;
 380         }
 381         metadata_stream->out_fd = ret;
 382
 383         ret = 0;
 384         while (ret >= 0) {
 385                 ret = lttng_kconsumer_read_subbuffer(metadata_stream, ctx);
 386                 if (ret < 0) {
 387                         if (ret != -EPERM) {
 388                                 ERR("Kernel snapshot reading subbuffer");
 389                                 goto end;
 390                         }
 391                         /* "ret" is negative at this point so we will exit the loop. */
 392                         continue;
 393                 }
 394         }
 395
 396         ret = 0;
 397 end:
 398         rcu_read_unlock();
 399         return ret;
 400 }
 401
 402 /*
 403  * Receive command from session daemon and process it.
 404  *
 405  * Return 1 on success else a negative value or 0.
 406  */
 407 int lttng_kconsumer_recv_cmd(struct lttng_consumer_local_data *ctx,
 408                 int sock, struct pollfd *consumer_sockpoll)
 409 {
 410         ssize_t ret;
 411         enum lttng_error_code ret_code = LTTNG_OK;
 412         struct lttcomm_consumer_msg msg;
 413
 414         ret = lttcomm_recv_unix_sock(sock, &msg, sizeof(msg));
 415         if (ret != sizeof(msg)) {
 416                 lttng_consumer_send_error(ctx, LTTCOMM_CONSUMERD_ERROR_RECV_CMD);
 417                 if (ret > 0) {
 418                         ret = -1;
 419                 }
 420                 return ret;
 421         }
 422         if (msg.cmd_type == LTTNG_CONSUMER_STOP) {
 423                 /*
 424                  * Notify the session daemon that the command is completed.
 425                  *
 426                  * On transport layer error, the function call will print an error
 427                  * message so handling the returned code is a bit useless since we
 428                  * return an error code anyway.
 429                  */
 430                 (void) consumer_send_status_msg(sock, ret_code);
 431                 return -ENOENT;
 432         }
 433
 434         /* relayd needs RCU read-side protection */
 435         rcu_read_lock();
 436
 437         switch (msg.cmd_type) {
 438         case LTTNG_CONSUMER_ADD_RELAYD_SOCKET:
 439         {
 440                 /* Session daemon status message are handled in the following call. */
 441                 ret = consumer_add_relayd_socket(msg.u.relayd_sock.net_index,
 442                                 msg.u.relayd_sock.type, ctx, sock, consumer_sockpoll,
 443                                 &msg.u.relayd_sock.sock, msg.u.relayd_sock.session_id);
 444                 goto end_nosignal;
 445         }
 446         case LTTNG_CONSUMER_ADD_CHANNEL:
 447         {
 448                 struct lttng_consumer_channel *new_channel;
 449                 int ret_recv;
 450
 451                 /* First send a status message before receiving the fds. */
 452                 ret = consumer_send_status_msg(sock, ret_code);
 453                 if (ret < 0) {
 454                         /* Somehow, the session daemon is not responding anymore. */
 455                         goto error_fatal;
 456                 }
 457                 DBG("consumer_add_channel %" PRIu64, msg.u.channel.channel_key);
 458                 new_channel = consumer_allocate_channel(msg.u.channel.channel_key,
 459                                 msg.u.channel.session_id, msg.u.channel.pathname,
 460                                 msg.u.channel.name, msg.u.channel.uid, msg.u.channel.gid,
 461                                 msg.u.channel.relayd_id, msg.u.channel.output,
 462                                 msg.u.channel.tracefile_size,
 463                                 msg.u.channel.tracefile_count,
 464                                 msg.u.channel.monitor);
 465                 if (new_channel == NULL) {
 466                         lttng_consumer_send_error(ctx, LTTCOMM_CONSUMERD_OUTFD_ERROR);
 467                         goto end_nosignal;
 468                 }
 469                 new_channel->nb_init_stream_left = msg.u.channel.nb_init_streams;
 470
 471                 /* Translate and save channel type. */
 472                 switch (msg.u.channel.type) {
 473                 case CONSUMER_CHANNEL_TYPE_DATA:
 474                 case CONSUMER_CHANNEL_TYPE_METADATA:
 475                         new_channel->type = msg.u.channel.type;
 476                         break;
 477                 default:
 478                         assert(0);
 479                         goto end_nosignal;
 480                 };
 481
 482                 if (ctx->on_recv_channel != NULL) {
 483                         ret_recv = ctx->on_recv_channel(new_channel);
 484                         if (ret_recv == 0) {
 485                                 ret = consumer_add_channel(new_channel, ctx);
 486                         } else if (ret_recv < 0) {
 487                                 goto end_nosignal;
 488                         }
 489                 } else {
 490                         ret = consumer_add_channel(new_channel, ctx);
 491                 }
 492
 493                 /* If we received an error in add_channel, we need to report it. */
 494                 if (ret < 0) {
 495                         ret = consumer_send_status_msg(sock, ret);
 496                         if (ret < 0) {
 497                                 goto error_fatal;
 498                         }
 499                         goto end_nosignal;
 500                 }
 501
 502                 goto end_nosignal;
 503         }
 504         case LTTNG_CONSUMER_ADD_STREAM:
 505         {
 506                 int fd;
 507                 struct lttng_pipe *stream_pipe;
 508                 struct lttng_consumer_stream *new_stream;
 509                 struct lttng_consumer_channel *channel;
 510                 int alloc_ret = 0;
 511
 512                 /*
 513                  * Get stream's channel reference. Needed when adding the stream to the
 514                  * global hash table.
 515                  */
 516                 channel = consumer_find_channel(msg.u.stream.channel_key);
 517                 if (!channel) {
 518                         /*
 519                          * We could not find the channel. Can happen if cpu hotplug
 520                          * happens while tearing down.
 521                          */
 522                         ERR("Unable to find channel key %" PRIu64, msg.u.stream.channel_key);
 523                         ret_code = LTTNG_ERR_KERN_CHAN_NOT_FOUND;
 524                 }
 525
 526                 /* First send a status message before receiving the fds. */
 527                 ret = consumer_send_status_msg(sock, ret_code);
 528                 if (ret < 0) {
 529                         /*
 530                          * Somehow, the session daemon is not responding
 531                          * anymore.
 532                          */
 533                         goto error_fatal;
 534                 }
 535                 if (ret_code != LTTNG_OK) {
 536                         /*
 537                          * Channel was not found.
 538                          */
 539                         goto end_nosignal;
 540                 }
 541
 542                 /* block */
 543                 if (lttng_consumer_poll_socket(consumer_sockpoll) < 0) {
 544                         rcu_read_unlock();
 545                         return -EINTR;
 546                 }
 547
 548                 /* Get stream file descriptor from socket */
 549                 ret = lttcomm_recv_fds_unix_sock(sock, &fd, 1);
 550                 if (ret != sizeof(fd)) {
 551                         lttng_consumer_send_error(ctx, LTTCOMM_CONSUMERD_ERROR_RECV_FD);
 552                         rcu_read_unlock();
 553                         return ret;
 554                 }
 555
 556                 /*
 557                  * Send status code to session daemon only if the recv works. If the
 558                  * above recv() failed, the session daemon is notified through the
 559                  * error socket and the teardown is eventually done.
 560                  */
 561                 ret = consumer_send_status_msg(sock, ret_code);
 562                 if (ret < 0) {
 563                         /* Somehow, the session daemon is not responding anymore. */
 564                         goto end_nosignal;
 565                 }
 566
 567                 new_stream = consumer_allocate_stream(channel->key,
 568                                 fd,
 569                                 LTTNG_CONSUMER_ACTIVE_STREAM,
 570                                 channel->name,
 571                                 channel->uid,
 572                                 channel->gid,
 573                                 channel->relayd_id,
 574                                 channel->session_id,
 575                                 msg.u.stream.cpu,
 576                                 &alloc_ret,
 577                                 channel->type);
 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                 new_stream->chan = channel;
 589                 new_stream->wait_fd = fd;
 590                 switch (channel->output) {
 591                 case CONSUMER_CHANNEL_SPLICE:
 592                         new_stream->output = LTTNG_EVENT_SPLICE;
 593                         break;
 594                 case CONSUMER_CHANNEL_MMAP:
 595                         new_stream->output = LTTNG_EVENT_MMAP;
 596                         break;
 597                 default:
 598                         ERR("Stream output unknown %d", channel->output);
 599                         goto end_nosignal;
 600                 }
 601
 602                 /*
 603                  * We've just assigned the channel to the stream so increment the
 604                  * refcount right now. We don't need to increment the refcount for
 605                  * streams in no monitor because we handle manually the cleanup of
 606                  * those. It is very important to make sure there is NO prior
 607                  * consumer_del_stream() calls or else the refcount will be unbalanced.
 608                  */
 609                 if (channel->monitor) {
 610                         uatomic_inc(&new_stream->chan->refcount);
 611                 }
 612
 613                 /*
 614                  * The buffer flush is done on the session daemon side for the kernel
 615                  * so no need for the stream "hangup_flush_done" variable to be
 616                  * tracked. This is important for a kernel stream since we don't rely
 617                  * on the flush state of the stream to read data. It's not the case for
 618                  * user space tracing.
 619                  */
 620                 new_stream->hangup_flush_done = 0;
 621
 622                 ret = send_relayd_stream(new_stream, NULL);
 623                 if (ret < 0) {
 624                         consumer_del_stream(new_stream, NULL);
 625                         goto end_nosignal;
 626                 }
 627
 628                 if (ctx->on_recv_stream) {
 629                         ret = ctx->on_recv_stream(new_stream);
 630                         if (ret < 0) {
 631                                 consumer_del_stream(new_stream, NULL);
 632                                 goto end_nosignal;
 633                         }
 634                 }
 635
 636                 if (new_stream->metadata_flag) {
 637                         channel->metadata_stream = new_stream;
 638                 }
 639
 640                 /* Do not monitor this stream. */
 641                 if (!channel->monitor) {
 642                         DBG("Kernel consumer add stream %s in no monitor mode with"
 643                                         "relayd id %" PRIu64, new_stream->name,
 644                                         new_stream->relayd_stream_id);
 645                         cds_list_add(&new_stream->no_monitor_node,
 646                                         &channel->stream_no_monitor_list.head);
 647                         break;
 648                 }
 649
 650                 /* Get the right pipe where the stream will be sent. */
 651                 if (new_stream->metadata_flag) {
 652                         stream_pipe = ctx->consumer_metadata_pipe;
 653                 } else {
 654                         stream_pipe = ctx->consumer_data_pipe;
 655                 }
 656
 657                 ret = lttng_pipe_write(stream_pipe, &new_stream, sizeof(new_stream));
 658                 if (ret < 0) {
 659                         ERR("Consumer write %s stream to pipe %d",
 660                                         new_stream->metadata_flag ? "metadata" : "data",
 661                                         lttng_pipe_get_writefd(stream_pipe));
 662                         consumer_del_stream(new_stream, NULL);
 663                         goto end_nosignal;
 664                 }
 665
 666                 DBG("Kernel consumer ADD_STREAM %s (fd: %d) with relayd id %" PRIu64,
 667                                 new_stream->name, fd, new_stream->relayd_stream_id);
 668                 break;
 669         }
 670         case LTTNG_CONSUMER_UPDATE_STREAM:
 671         {
 672                 rcu_read_unlock();
 673                 return -ENOSYS;
 674         }
 675         case LTTNG_CONSUMER_DESTROY_RELAYD:
 676         {
 677                 uint64_t index = msg.u.destroy_relayd.net_seq_idx;
 678                 struct consumer_relayd_sock_pair *relayd;
 679
 680                 DBG("Kernel consumer destroying relayd %" PRIu64, index);
 681
 682                 /* Get relayd reference if exists. */
 683                 relayd = consumer_find_relayd(index);
 684                 if (relayd == NULL) {
 685                         DBG("Unable to find relayd %" PRIu64, index);
 686                         ret_code = LTTNG_ERR_NO_CONSUMER;
 687                 }
 688
 689                 /*
 690                  * Each relayd socket pair has a refcount of stream attached to it
 691                  * which tells if the relayd is still active or not depending on the
 692                  * refcount value.
 693                  *
 694                  * This will set the destroy flag of the relayd object and destroy it
 695                  * if the refcount reaches zero when called.
 696                  *
 697                  * The destroy can happen either here or when a stream fd hangs up.
 698                  */
 699                 if (relayd) {
 700                         consumer_flag_relayd_for_destroy(relayd);
 701                 }
 702
 703                 ret = consumer_send_status_msg(sock, ret_code);
 704                 if (ret < 0) {
 705                         /* Somehow, the session daemon is not responding anymore. */
 706                         goto error_fatal;
 707                 }
 708
 709                 goto end_nosignal;
 710         }
 711         case LTTNG_CONSUMER_DATA_PENDING:
 712         {
 713                 int32_t ret;
 714                 uint64_t id = msg.u.data_pending.session_id;
 715
 716                 DBG("Kernel consumer data pending command for id %" PRIu64, id);
 717
 718                 ret = consumer_data_pending(id);
 719
 720                 /* Send back returned value to session daemon */
 721                 ret = lttcomm_send_unix_sock(sock, &ret, sizeof(ret));
 722                 if (ret < 0) {
 723                         PERROR("send data pending ret code");
 724                         goto error_fatal;
 725                 }
 726
 727                 /*
 728                  * No need to send back a status message since the data pending
 729                  * returned value is the response.
 730                  */
 731                 break;
 732         }
 733         case LTTNG_CONSUMER_SNAPSHOT_CHANNEL:
 734         {
 735                 if (msg.u.snapshot_channel.metadata == 1) {
 736                         ret = lttng_kconsumer_snapshot_metadata(msg.u.snapshot_channel.key,
 737                                         msg.u.snapshot_channel.pathname, ctx);
 738                         if (ret < 0) {
 739                                 ERR("Snapshot metadata failed");
 740                                 ret_code = LTTNG_ERR_KERN_META_FAIL;
 741                         }
 742                 } else {
 743                         ret = lttng_kconsumer_snapshot_channel(msg.u.snapshot_channel.key,
 744                                         msg.u.snapshot_channel.pathname,
 745                                         msg.u.snapshot_channel.relayd_id, ctx);
 746                         if (ret < 0) {
 747                                 ERR("Snapshot channel failed");
 748                                 ret_code = LTTNG_ERR_KERN_CHAN_FAIL;
 749                         }
 750                 }
 751
 752                 ret = consumer_send_status_msg(sock, ret_code);
 753                 if (ret < 0) {
 754                         /* Somehow, the session daemon is not responding anymore. */
 755                         goto end_nosignal;
 756                 }
 757                 break;
 758         }
 759         case LTTNG_CONSUMER_DESTROY_CHANNEL:
 760         {
 761                 uint64_t key = msg.u.destroy_channel.key;
 762                 struct lttng_consumer_channel *channel;
 763
 764                 channel = consumer_find_channel(key);
 765                 if (!channel) {
 766                         ERR("Kernel consumer destroy channel %" PRIu64 " not found", key);
 767                         ret_code = LTTNG_ERR_KERN_CHAN_NOT_FOUND;
 768                 }
 769
 770                 ret = consumer_send_status_msg(sock, ret_code);
 771                 if (ret < 0) {
 772                         /* Somehow, the session daemon is not responding anymore. */
 773                         goto end_nosignal;
 774                 }
 775
 776                 /*
 777                  * This command should ONLY be issued for channel with streams set in
 778                  * no monitor mode.
 779                  */
 780                 assert(!channel->monitor);
 781
 782                 /*
 783                  * The refcount should ALWAYS be 0 in the case of a channel in no
 784                  * monitor mode.
 785                  */
 786                 assert(!uatomic_sub_return(&channel->refcount, 1));
 787
 788                 consumer_del_channel(channel);
 789
 790                 goto end_nosignal;
 791         }
 792         default:
 793                 goto end_nosignal;
 794         }
 795
 796 end_nosignal:
 797         rcu_read_unlock();
 798
 799         /*
 800          * Return 1 to indicate success since the 0 value can be a socket
 801          * shutdown during the recv() or send() call.
 802          */
 803         return 1;
 804
 805 error_fatal:
 806         rcu_read_unlock();
 807         /* This will issue a consumer stop. */
 808         return -1;
 809 }
 810
 811 /*
 812  * Consume data on a file descriptor and write it on a trace file.
 813  */
 814 ssize_t lttng_kconsumer_read_subbuffer(struct lttng_consumer_stream *stream,
 815                 struct lttng_consumer_local_data *ctx)
 816 {
 817         unsigned long len, subbuf_size, padding;
 818         int err;
 819         ssize_t ret = 0;
 820         int infd = stream->wait_fd;
 821
 822         DBG("In read_subbuffer (infd : %d)", infd);
 823         /* Get the next subbuffer */
 824         err = kernctl_get_next_subbuf(infd);
 825         if (err != 0) {
 826                 ret = err;
 827                 /*
 828                  * This is a debug message even for single-threaded consumer,
 829                  * because poll() have more relaxed criterions than get subbuf,
 830                  * so get_subbuf may fail for short race windows where poll()
 831                  * would issue wakeups.
 832                  */
 833                 DBG("Reserving sub buffer failed (everything is normal, "
 834                                 "it is due to concurrency)");
 835                 goto end;
 836         }
 837
 838         /* Get the full subbuffer size including padding */
 839         err = kernctl_get_padded_subbuf_size(infd, &len);
 840         if (err != 0) {
 841                 errno = -err;
 842                 perror("Getting sub-buffer len failed.");
 843                 ret = err;
 844                 goto end;
 845         }
 846
 847         switch (stream->chan->output) {
 848         case CONSUMER_CHANNEL_SPLICE:
 849                 /*
 850                  * XXX: The lttng-modules splice "actor" does not handle copying
 851                  * partial pages hence only using the subbuffer size without the
 852                  * padding makes the splice fail.
 853                  */
 854                 subbuf_size = len;
 855                 padding = 0;
 856
 857                 /* splice the subbuffer to the tracefile */
 858                 ret = lttng_consumer_on_read_subbuffer_splice(ctx, stream, subbuf_size,
 859                                 padding);
 860                 /*
 861                  * XXX: Splice does not support network streaming so the return value
 862                  * is simply checked against subbuf_size and not like the mmap() op.
 863                  */
 864                 if (ret != subbuf_size) {
 865                         /*
 866                          * display the error but continue processing to try
 867                          * to release the subbuffer
 868                          */
 869                         ERR("Error splicing to tracefile (ret: %zd != len: %lu)",
 870                                         ret, subbuf_size);
 871                 }
 872                 break;
 873         case CONSUMER_CHANNEL_MMAP:
 874                 /* Get subbuffer size without padding */
 875                 err = kernctl_get_subbuf_size(infd, &subbuf_size);
 876                 if (err != 0) {
 877                         errno = -err;
 878                         perror("Getting sub-buffer len failed.");
 879                         ret = err;
 880                         goto end;
 881                 }
 882
 883                 /* Make sure the tracer is not gone mad on us! */
 884                 assert(len >= subbuf_size);
 885
 886                 padding = len - subbuf_size;
 887
 888                 /* write the subbuffer to the tracefile */
 889                 ret = lttng_consumer_on_read_subbuffer_mmap(ctx, stream, subbuf_size,
 890                                 padding);
 891                 /*
 892                  * The mmap operation should write subbuf_size amount of data when
 893                  * network streaming or the full padding (len) size when we are _not_
 894                  * streaming.
 895                  */
 896                 if ((ret != subbuf_size && stream->net_seq_idx != (uint64_t) -1ULL) ||
 897                                 (ret != len && stream->net_seq_idx == (uint64_t) -1ULL)) {
 898                         /*
 899                          * Display the error but continue processing to try to release the
 900                          * subbuffer
 901                          */
 902                         ERR("Error writing to tracefile "
 903                                         "(ret: %zd != len: %lu != subbuf_size: %lu)",
 904                                         ret, len, subbuf_size);
 905                 }
 906                 break;
 907         default:
 908                 ERR("Unknown output method");
 909                 ret = -1;
 910         }
 911
 912         err = kernctl_put_next_subbuf(infd);
 913         if (err != 0) {
 914                 errno = -err;
 915                 if (errno == EFAULT) {
 916                         perror("Error in unreserving sub buffer\n");
 917                 } else if (errno == EIO) {
 918                         /* Should never happen with newer LTTng versions */
 919                         perror("Reader has been pushed by the writer, last sub-buffer corrupted.");
 920                 }
 921
 922                 ret = -err;
 923                 goto end;
 924         }
 925
 926 end:
 927         return ret;
 928 }
 929
 930 int lttng_kconsumer_on_recv_stream(struct lttng_consumer_stream *stream)
 931 {
 932         int ret;
 933
 934         assert(stream);
 935
 936         /*
 937          * Don't create anything if this is set for streaming or should not be
 938          * monitored.
 939          */
 940         if (stream->net_seq_idx == (uint64_t) -1ULL && stream->chan->monitor) {
 941                 ret = utils_create_stream_file(stream->chan->pathname, stream->name,
 942                                 stream->chan->tracefile_size, stream->tracefile_count_current,
 943                                 stream->uid, stream->gid);
 944                 if (ret < 0) {
 945                         goto error;
 946                 }
 947                 stream->out_fd = ret;
 948                 stream->tracefile_size_current = 0;
 949         }
 950
 951         if (stream->output == LTTNG_EVENT_MMAP) {
 952                 /* get the len of the mmap region */
 953                 unsigned long mmap_len;
 954
 955                 ret = kernctl_get_mmap_len(stream->wait_fd, &mmap_len);
 956                 if (ret != 0) {
 957                         errno = -ret;
 958                         PERROR("kernctl_get_mmap_len");
 959                         goto error_close_fd;
 960                 }
 961                 stream->mmap_len = (size_t) mmap_len;
 962
 963                 stream->mmap_base = mmap(NULL, stream->mmap_len, PROT_READ,
 964                                 MAP_PRIVATE, stream->wait_fd, 0);
 965                 if (stream->mmap_base == MAP_FAILED) {
 966                         PERROR("Error mmaping");
 967                         ret = -1;
 968                         goto error_close_fd;
 969                 }
 970         }
 971
 972         /* we return 0 to let the library handle the FD internally */
 973         return 0;
 974
 975 error_close_fd:
 976         {
 977                 int err;
 978
 979                 err = close(stream->out_fd);
 980                 assert(!err);
 981         }
 982 error:
 983         return ret;
 984 }
 985
 986 /*
 987  * Check if data is still being extracted from the buffers for a specific
 988  * stream. Consumer data lock MUST be acquired before calling this function
 989  * and the stream lock.
 990  *
 991  * Return 1 if the traced data are still getting read else 0 meaning that the
 992  * data is available for trace viewer reading.
 993  */
 994 int lttng_kconsumer_data_pending(struct lttng_consumer_stream *stream)
 995 {
 996         int ret;
 997
 998         assert(stream);
 999
1000         ret = kernctl_get_next_subbuf(stream->wait_fd);
1001         if (ret == 0) {
1002                 /* There is still data so let's put back this subbuffer. */
1003                 ret = kernctl_put_subbuf(stream->wait_fd);
1004                 assert(ret == 0);
1005                 ret = 1;   /* Data is pending */
1006                 goto end;
1007         }
1008
1009         /* Data is NOT pending and ready to be read. */
1010         ret = 0;
1011
1012 end:
1013         return ret;
1014 }