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