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
  41 #include "kernel-consumer.h"
  42
  43 extern struct lttng_consumer_global_data consumer_data;
  44 extern int consumer_poll_timeout;
  45 extern volatile int consumer_quit;
  46
  47 /*
  48  * Take a snapshot for a specific fd
  49  *
  50  * Returns 0 on success, < 0 on error
  51  */
  52 int lttng_kconsumer_take_snapshot(struct lttng_consumer_stream *stream)
  53 {
  54         int ret = 0;
  55         int infd = stream->wait_fd;
  56
  57         ret = kernctl_snapshot(infd);
  58         if (ret != 0) {
  59                 errno = -ret;
  60                 perror("Getting sub-buffer snapshot.");
  61         }
  62
  63         return ret;
  64 }
  65
  66 /*
  67  * Get the produced position
  68  *
  69  * Returns 0 on success, < 0 on error
  70  */
  71 int lttng_kconsumer_get_produced_snapshot(struct lttng_consumer_stream *stream,
  72                 unsigned long *pos)
  73 {
  74         int ret;
  75         int infd = stream->wait_fd;
  76
  77         ret = kernctl_snapshot_get_produced(infd, pos);
  78         if (ret != 0) {
  79                 errno = -ret;
  80                 perror("kernctl_snapshot_get_produced");
  81         }
  82
  83         return ret;
  84 }
  85
  86 /*
  87  * Receive command from session daemon and process it.
  88  *
  89  * Return 1 on success else a negative value or 0.
  90  */
  91 int lttng_kconsumer_recv_cmd(struct lttng_consumer_local_data *ctx,
  92                 int sock, struct pollfd *consumer_sockpoll)
  93 {
  94         ssize_t ret;
  95         enum lttng_error_code ret_code = LTTNG_OK;
  96         struct lttcomm_consumer_msg msg;
  97
  98         ret = lttcomm_recv_unix_sock(sock, &msg, sizeof(msg));
  99         if (ret != sizeof(msg)) {
 100                 lttng_consumer_send_error(ctx, LTTCOMM_CONSUMERD_ERROR_RECV_CMD);
 101                 if (ret > 0) {
 102                         ret = -1;
 103                 }
 104                 return ret;
 105         }
 106         if (msg.cmd_type == LTTNG_CONSUMER_STOP) {
 107                 /*
 108                  * Notify the session daemon that the command is completed.
 109                  *
 110                  * On transport layer error, the function call will print an error
 111                  * message so handling the returned code is a bit useless since we
 112                  * return an error code anyway.
 113                  */
 114                 (void) consumer_send_status_msg(sock, ret_code);
 115                 return -ENOENT;
 116         }
 117
 118         /* relayd needs RCU read-side protection */
 119         rcu_read_lock();
 120
 121         switch (msg.cmd_type) {
 122         case LTTNG_CONSUMER_ADD_RELAYD_SOCKET:
 123         {
 124                 /* Session daemon status message are handled in the following call. */
 125                 ret = consumer_add_relayd_socket(msg.u.relayd_sock.net_index,
 126                                 msg.u.relayd_sock.type, ctx, sock, consumer_sockpoll,
 127                                 &msg.u.relayd_sock.sock, msg.u.relayd_sock.session_id);
 128                 goto end_nosignal;
 129         }
 130         case LTTNG_CONSUMER_ADD_CHANNEL:
 131         {
 132                 struct lttng_consumer_channel *new_channel;
 133                 int ret_recv;
 134
 135                 /* First send a status message before receiving the fds. */
 136                 ret = consumer_send_status_msg(sock, ret_code);
 137                 if (ret < 0) {
 138                         /* Somehow, the session daemon is not responding anymore. */
 139                         goto error_fatal;
 140                 }
 141                 DBG("consumer_add_channel %" PRIu64, msg.u.channel.channel_key);
 142                 new_channel = consumer_allocate_channel(msg.u.channel.channel_key,
 143                                 msg.u.channel.session_id, msg.u.channel.pathname,
 144                                 msg.u.channel.name, msg.u.channel.uid, msg.u.channel.gid,
 145                                 msg.u.channel.relayd_id, msg.u.channel.output,
 146                                 msg.u.channel.tracefile_size,
 147                                 msg.u.channel.tracefile_count);
 148                 if (new_channel == NULL) {
 149                         lttng_consumer_send_error(ctx, LTTCOMM_CONSUMERD_OUTFD_ERROR);
 150                         goto end_nosignal;
 151                 }
 152                 new_channel->nb_init_stream_left = msg.u.channel.nb_init_streams;
 153
 154                 /* Translate and save channel type. */
 155                 switch (msg.u.channel.type) {
 156                 case CONSUMER_CHANNEL_TYPE_DATA:
 157                 case CONSUMER_CHANNEL_TYPE_METADATA:
 158                         new_channel->type = msg.u.channel.type;
 159                         break;
 160                 default:
 161                         assert(0);
 162                         goto end_nosignal;
 163                 };
 164
 165                 if (ctx->on_recv_channel != NULL) {
 166                         ret_recv = ctx->on_recv_channel(new_channel);
 167                         if (ret_recv == 0) {
 168                                 ret = consumer_add_channel(new_channel, ctx);
 169                         } else if (ret_recv < 0) {
 170                                 goto end_nosignal;
 171                         }
 172                 } else {
 173                         ret = consumer_add_channel(new_channel, ctx);
 174                 }
 175
 176                 /* If we received an error in add_channel, we need to report it. */
 177                 if (ret < 0) {
 178                         ret = consumer_send_status_msg(sock, ret);
 179                         if (ret < 0) {
 180                                 goto error_fatal;
 181                         }
 182                         goto end_nosignal;
 183                 }
 184
 185                 goto end_nosignal;
 186         }
 187         case LTTNG_CONSUMER_ADD_STREAM:
 188         {
 189                 int fd;
 190                 struct lttng_pipe *stream_pipe;
 191                 struct consumer_relayd_sock_pair *relayd = NULL;
 192                 struct lttng_consumer_stream *new_stream;
 193                 struct lttng_consumer_channel *channel;
 194                 int alloc_ret = 0;
 195
 196                 /*
 197                  * Get stream's channel reference. Needed when adding the stream to the
 198                  * global hash table.
 199                  */
 200                 channel = consumer_find_channel(msg.u.stream.channel_key);
 201                 if (!channel) {
 202                         /*
 203                          * We could not find the channel. Can happen if cpu hotplug
 204                          * happens while tearing down.
 205                          */
 206                         ERR("Unable to find channel key %" PRIu64, msg.u.stream.channel_key);
 207                         ret_code = LTTNG_ERR_KERN_CHAN_NOT_FOUND;
 208                 }
 209
 210                 /* First send a status message before receiving the fds. */
 211                 ret = consumer_send_status_msg(sock, ret_code);
 212                 if (ret < 0) {
 213                         /*
 214                          * Somehow, the session daemon is not responding
 215                          * anymore.
 216                          */
 217                         goto error_fatal;
 218                 }
 219                 if (ret_code != LTTNG_OK) {
 220                         /*
 221                          * Channel was not found.
 222                          */
 223                         goto end_nosignal;
 224                 }
 225
 226                 /* block */
 227                 if (lttng_consumer_poll_socket(consumer_sockpoll) < 0) {
 228                         rcu_read_unlock();
 229                         return -EINTR;
 230                 }
 231
 232                 /* Get stream file descriptor from socket */
 233                 ret = lttcomm_recv_fds_unix_sock(sock, &fd, 1);
 234                 if (ret != sizeof(fd)) {
 235                         lttng_consumer_send_error(ctx, LTTCOMM_CONSUMERD_ERROR_RECV_FD);
 236                         rcu_read_unlock();
 237                         return ret;
 238                 }
 239
 240                 /*
 241                  * Send status code to session daemon only if the recv works. If the
 242                  * above recv() failed, the session daemon is notified through the
 243                  * error socket and the teardown is eventually done.
 244                  */
 245                 ret = consumer_send_status_msg(sock, ret_code);
 246                 if (ret < 0) {
 247                         /* Somehow, the session daemon is not responding anymore. */
 248                         goto end_nosignal;
 249                 }
 250
 251                 new_stream = consumer_allocate_stream(channel->key,
 252                                 fd,
 253                                 LTTNG_CONSUMER_ACTIVE_STREAM,
 254                                 channel->name,
 255                                 channel->uid,
 256                                 channel->gid,
 257                                 channel->relayd_id,
 258                                 channel->session_id,
 259                                 msg.u.stream.cpu,
 260                                 &alloc_ret,
 261                                 channel->type);
 262                 if (new_stream == NULL) {
 263                         switch (alloc_ret) {
 264                         case -ENOMEM:
 265                         case -EINVAL:
 266                         default:
 267                                 lttng_consumer_send_error(ctx, LTTCOMM_CONSUMERD_OUTFD_ERROR);
 268                                 break;
 269                         }
 270                         goto end_nosignal;
 271                 }
 272                 new_stream->chan = channel;
 273                 new_stream->wait_fd = fd;
 274
 275                 /*
 276                  * We've just assigned the channel to the stream so increment the
 277                  * refcount right now.
 278                  */
 279                 uatomic_inc(&new_stream->chan->refcount);
 280
 281                 /*
 282                  * The buffer flush is done on the session daemon side for the kernel
 283                  * so no need for the stream "hangup_flush_done" variable to be
 284                  * tracked. This is important for a kernel stream since we don't rely
 285                  * on the flush state of the stream to read data. It's not the case for
 286                  * user space tracing.
 287                  */
 288                 new_stream->hangup_flush_done = 0;
 289
 290                 /* The stream is not metadata. Get relayd reference if exists. */
 291                 relayd = consumer_find_relayd(new_stream->net_seq_idx);
 292                 if (relayd != NULL) {
 293                         /* Add stream on the relayd */
 294                         pthread_mutex_lock(&relayd->ctrl_sock_mutex);
 295                         ret = relayd_add_stream(&relayd->control_sock,
 296                                         new_stream->name, new_stream->chan->pathname,
 297                                         &new_stream->relayd_stream_id,
 298                                         new_stream->chan->tracefile_size,
 299                                         new_stream->chan->tracefile_count);
 300                         pthread_mutex_unlock(&relayd->ctrl_sock_mutex);
 301                         if (ret < 0) {
 302                                 consumer_del_stream(new_stream, NULL);
 303                                 goto end_nosignal;
 304                         }
 305                 } else if (new_stream->net_seq_idx != (uint64_t) -1ULL) {
 306                         ERR("Network sequence index %" PRIu64 " unknown. Not adding stream.",
 307                                         new_stream->net_seq_idx);
 308                         consumer_del_stream(new_stream, NULL);
 309                         goto end_nosignal;
 310                 }
 311
 312                 if (ctx->on_recv_stream) {
 313                         ret = ctx->on_recv_stream(new_stream);
 314                         if (ret < 0) {
 315                                 consumer_del_stream(new_stream, NULL);
 316                                 goto end_nosignal;
 317                         }
 318                 }
 319
 320                 if (msg.u.stream.no_monitor) {
 321                         DBG("Kernel consumer add stream %s in no monitor mode with"
 322                                         "relayd id %" PRIu64, new_stream->name,
 323                                         new_stream->relayd_stream_id);
 324                         break;
 325                 }
 326
 327                 /* Get the right pipe where the stream will be sent. */
 328                 if (new_stream->metadata_flag) {
 329                         stream_pipe = ctx->consumer_metadata_pipe;
 330                 } else {
 331                         stream_pipe = ctx->consumer_data_pipe;
 332                 }
 333
 334                 ret = lttng_pipe_write(stream_pipe, &new_stream, sizeof(new_stream));
 335                 if (ret < 0) {
 336                         ERR("Consumer write %s stream to pipe %d",
 337                                         new_stream->metadata_flag ? "metadata" : "data",
 338                                         lttng_pipe_get_writefd(stream_pipe));
 339                         consumer_del_stream(new_stream, NULL);
 340                         goto end_nosignal;
 341                 }
 342
 343                 DBG("Kernel consumer ADD_STREAM %s (fd: %d) with relayd id %" PRIu64,
 344                                 new_stream->name, fd, new_stream->relayd_stream_id);
 345                 break;
 346         }
 347         case LTTNG_CONSUMER_UPDATE_STREAM:
 348         {
 349                 rcu_read_unlock();
 350                 return -ENOSYS;
 351         }
 352         case LTTNG_CONSUMER_DESTROY_RELAYD:
 353         {
 354                 uint64_t index = msg.u.destroy_relayd.net_seq_idx;
 355                 struct consumer_relayd_sock_pair *relayd;
 356
 357                 DBG("Kernel consumer destroying relayd %" PRIu64, index);
 358
 359                 /* Get relayd reference if exists. */
 360                 relayd = consumer_find_relayd(index);
 361                 if (relayd == NULL) {
 362                         DBG("Unable to find relayd %" PRIu64, index);
 363                         ret_code = LTTNG_ERR_NO_CONSUMER;
 364                 }
 365
 366                 /*
 367                  * Each relayd socket pair has a refcount of stream attached to it
 368                  * which tells if the relayd is still active or not depending on the
 369                  * refcount value.
 370                  *
 371                  * This will set the destroy flag of the relayd object and destroy it
 372                  * if the refcount reaches zero when called.
 373                  *
 374                  * The destroy can happen either here or when a stream fd hangs up.
 375                  */
 376                 if (relayd) {
 377                         consumer_flag_relayd_for_destroy(relayd);
 378                 }
 379
 380                 ret = consumer_send_status_msg(sock, ret_code);
 381                 if (ret < 0) {
 382                         /* Somehow, the session daemon is not responding anymore. */
 383                         goto error_fatal;
 384                 }
 385
 386                 goto end_nosignal;
 387         }
 388         case LTTNG_CONSUMER_DATA_PENDING:
 389         {
 390                 int32_t ret;
 391                 uint64_t id = msg.u.data_pending.session_id;
 392
 393                 DBG("Kernel consumer data pending command for id %" PRIu64, id);
 394
 395                 ret = consumer_data_pending(id);
 396
 397                 /* Send back returned value to session daemon */
 398                 ret = lttcomm_send_unix_sock(sock, &ret, sizeof(ret));
 399                 if (ret < 0) {
 400                         PERROR("send data pending ret code");
 401                         goto error_fatal;
 402                 }
 403
 404                 /*
 405                  * No need to send back a status message since the data pending
 406                  * returned value is the response.
 407                  */
 408                 break;
 409         }
 410         case LTTNG_CONSUMER_SNAPSHOT_CHANNEL:
 411         {
 412                 ret = consumer_send_status_msg(sock, ret_code);
 413                 if (ret < 0) {
 414                         /* Somehow, the session daemon is not responding anymore. */
 415                         goto end_nosignal;
 416                 }
 417                 break;
 418         }
 419         default:
 420                 goto end_nosignal;
 421         }
 422
 423 end_nosignal:
 424         rcu_read_unlock();
 425
 426         /*
 427          * Return 1 to indicate success since the 0 value can be a socket
 428          * shutdown during the recv() or send() call.
 429          */
 430         return 1;
 431
 432 error_fatal:
 433         rcu_read_unlock();
 434         /* This will issue a consumer stop. */
 435         return -1;
 436 }
 437
 438 /*
 439  * Consume data on a file descriptor and write it on a trace file.
 440  */
 441 ssize_t lttng_kconsumer_read_subbuffer(struct lttng_consumer_stream *stream,
 442                 struct lttng_consumer_local_data *ctx)
 443 {
 444         unsigned long len, subbuf_size, padding;
 445         int err;
 446         ssize_t ret = 0;
 447         int infd = stream->wait_fd;
 448
 449         DBG("In read_subbuffer (infd : %d)", infd);
 450         /* Get the next subbuffer */
 451         err = kernctl_get_next_subbuf(infd);
 452         if (err != 0) {
 453                 ret = err;
 454                 /*
 455                  * This is a debug message even for single-threaded consumer,
 456                  * because poll() have more relaxed criterions than get subbuf,
 457                  * so get_subbuf may fail for short race windows where poll()
 458                  * would issue wakeups.
 459                  */
 460                 DBG("Reserving sub buffer failed (everything is normal, "
 461                                 "it is due to concurrency)");
 462                 goto end;
 463         }
 464
 465         /* Get the full subbuffer size including padding */
 466         err = kernctl_get_padded_subbuf_size(infd, &len);
 467         if (err != 0) {
 468                 errno = -err;
 469                 perror("Getting sub-buffer len failed.");
 470                 ret = err;
 471                 goto end;
 472         }
 473
 474         switch (stream->chan->output) {
 475         case LTTNG_EVENT_SPLICE:
 476
 477                 /*
 478                  * XXX: The lttng-modules splice "actor" does not handle copying
 479                  * partial pages hence only using the subbuffer size without the
 480                  * padding makes the splice fail.
 481                  */
 482                 subbuf_size = len;
 483                 padding = 0;
 484
 485                 /* splice the subbuffer to the tracefile */
 486                 ret = lttng_consumer_on_read_subbuffer_splice(ctx, stream, subbuf_size,
 487                                 padding);
 488                 /*
 489                  * XXX: Splice does not support network streaming so the return value
 490                  * is simply checked against subbuf_size and not like the mmap() op.
 491                  */
 492                 if (ret != subbuf_size) {
 493                         /*
 494                          * display the error but continue processing to try
 495                          * to release the subbuffer
 496                          */
 497                         ERR("Error splicing to tracefile (ret: %zd != len: %lu)",
 498                                         ret, subbuf_size);
 499                 }
 500                 break;
 501         case LTTNG_EVENT_MMAP:
 502                 /* Get subbuffer size without padding */
 503                 err = kernctl_get_subbuf_size(infd, &subbuf_size);
 504                 if (err != 0) {
 505                         errno = -err;
 506                         perror("Getting sub-buffer len failed.");
 507                         ret = err;
 508                         goto end;
 509                 }
 510
 511                 /* Make sure the tracer is not gone mad on us! */
 512                 assert(len >= subbuf_size);
 513
 514                 padding = len - subbuf_size;
 515
 516                 /* write the subbuffer to the tracefile */
 517                 ret = lttng_consumer_on_read_subbuffer_mmap(ctx, stream, subbuf_size,
 518                                 padding);
 519                 /*
 520                  * The mmap operation should write subbuf_size amount of data when
 521                  * network streaming or the full padding (len) size when we are _not_
 522                  * streaming.
 523                  */
 524                 if ((ret != subbuf_size && stream->net_seq_idx != (uint64_t) -1ULL) ||
 525                                 (ret != len && stream->net_seq_idx == (uint64_t) -1ULL)) {
 526                         /*
 527                          * Display the error but continue processing to try to release the
 528                          * subbuffer
 529                          */
 530                         ERR("Error writing to tracefile "
 531                                         "(ret: %zd != len: %lu != subbuf_size: %lu)",
 532                                         ret, len, subbuf_size);
 533                 }
 534                 break;
 535         default:
 536                 ERR("Unknown output method");
 537                 ret = -1;
 538         }
 539
 540         err = kernctl_put_next_subbuf(infd);
 541         if (err != 0) {
 542                 errno = -err;
 543                 if (errno == EFAULT) {
 544                         perror("Error in unreserving sub buffer\n");
 545                 } else if (errno == EIO) {
 546                         /* Should never happen with newer LTTng versions */
 547                         perror("Reader has been pushed by the writer, last sub-buffer corrupted.");
 548                 }
 549
 550                 ret = -err;
 551                 goto end;
 552         }
 553
 554 end:
 555         return ret;
 556 }
 557
 558 int lttng_kconsumer_on_recv_stream(struct lttng_consumer_stream *stream)
 559 {
 560         int ret;
 561
 562         assert(stream);
 563
 564         /* Don't create anything if this is set for streaming. */
 565         if (stream->net_seq_idx == (uint64_t) -1ULL) {
 566                 ret = utils_create_stream_file(stream->chan->pathname, stream->name,
 567                                 stream->chan->tracefile_size, stream->tracefile_count_current,
 568                                 stream->uid, stream->gid);
 569                 if (ret < 0) {
 570                         goto error;
 571                 }
 572                 stream->out_fd = ret;
 573                 stream->tracefile_size_current = 0;
 574         }
 575
 576         if (stream->output == LTTNG_EVENT_MMAP) {
 577                 /* get the len of the mmap region */
 578                 unsigned long mmap_len;
 579
 580                 ret = kernctl_get_mmap_len(stream->wait_fd, &mmap_len);
 581                 if (ret != 0) {
 582                         errno = -ret;
 583                         PERROR("kernctl_get_mmap_len");
 584                         goto error_close_fd;
 585                 }
 586                 stream->mmap_len = (size_t) mmap_len;
 587
 588                 stream->mmap_base = mmap(NULL, stream->mmap_len, PROT_READ,
 589                                 MAP_PRIVATE, stream->wait_fd, 0);
 590                 if (stream->mmap_base == MAP_FAILED) {
 591                         PERROR("Error mmaping");
 592                         ret = -1;
 593                         goto error_close_fd;
 594                 }
 595         }
 596
 597         /* we return 0 to let the library handle the FD internally */
 598         return 0;
 599
 600 error_close_fd:
 601         {
 602                 int err;
 603
 604                 err = close(stream->out_fd);
 605                 assert(!err);
 606         }
 607 error:
 608         return ret;
 609 }
 610
 611 /*
 612  * Check if data is still being extracted from the buffers for a specific
 613  * stream. Consumer data lock MUST be acquired before calling this function
 614  * and the stream lock.
 615  *
 616  * Return 1 if the traced data are still getting read else 0 meaning that the
 617  * data is available for trace viewer reading.
 618  */
 619 int lttng_kconsumer_data_pending(struct lttng_consumer_stream *stream)
 620 {
 621         int ret;
 622
 623         assert(stream);
 624
 625         ret = kernctl_get_next_subbuf(stream->wait_fd);
 626         if (ret == 0) {
 627                 /* There is still data so let's put back this subbuffer. */
 628                 ret = kernctl_put_subbuf(stream->wait_fd);
 629                 assert(ret == 0);
 630                 ret = 1;   /* Data is pending */
 631                 goto end;
 632         }
 633
 634         /* Data is NOT pending and ready to be read. */
 635         ret = 0;
 636
 637 end:
 638         return ret;
 639 }