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