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/relayd/relayd.h>
  38
  39 #include "kernel-consumer.h"
  40
  41 extern struct lttng_consumer_global_data consumer_data;
  42 extern int consumer_poll_timeout;
  43 extern volatile int consumer_quit;
  44
  45 /*
  46  * Take a snapshot for a specific fd
  47  *
  48  * Returns 0 on success, < 0 on error
  49  */
  50 int lttng_kconsumer_take_snapshot(struct lttng_consumer_local_data *ctx,
  51                 struct lttng_consumer_stream *stream)
  52 {
  53         int ret = 0;
  54         int infd = stream->wait_fd;
  55
  56         ret = kernctl_snapshot(infd);
  57         if (ret != 0) {
  58                 errno = -ret;
  59                 perror("Getting sub-buffer snapshot.");
  60         }
  61
  62         return ret;
  63 }
  64
  65 /*
  66  * Get the produced position
  67  *
  68  * Returns 0 on success, < 0 on error
  69  */
  70 int lttng_kconsumer_get_produced_snapshot(
  71                 struct lttng_consumer_local_data *ctx,
  72                 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 int lttng_kconsumer_recv_cmd(struct lttng_consumer_local_data *ctx,
  88                 int sock, struct pollfd *consumer_sockpoll)
  89 {
  90         ssize_t ret;
  91         enum lttng_error_code ret_code = LTTNG_OK;
  92         struct lttcomm_consumer_msg msg;
  93
  94         ret = lttcomm_recv_unix_sock(sock, &msg, sizeof(msg));
  95         if (ret != sizeof(msg)) {
  96                 lttng_consumer_send_error(ctx, LTTCOMM_CONSUMERD_ERROR_RECV_CMD);
  97                 return ret;
  98         }
  99         if (msg.cmd_type == LTTNG_CONSUMER_STOP) {
 100                 /*
 101                  * Notify the session daemon that the command is completed.
 102                  *
 103                  * On transport layer error, the function call will print an error
 104                  * message so handling the returned code is a bit useless since we
 105                  * return an error code anyway.
 106                  */
 107                 (void) consumer_send_status_msg(sock, ret_code);
 108                 return -ENOENT;
 109         }
 110
 111         /* relayd needs RCU read-side protection */
 112         rcu_read_lock();
 113
 114         switch (msg.cmd_type) {
 115         case LTTNG_CONSUMER_ADD_RELAYD_SOCKET:
 116         {
 117                 /* Session daemon status message are handled in the following call. */
 118                 ret = consumer_add_relayd_socket(msg.u.relayd_sock.net_index,
 119                                 msg.u.relayd_sock.type, ctx, sock, consumer_sockpoll,
 120                                 &msg.u.relayd_sock.sock, msg.u.relayd_sock.session_id);
 121                 goto end_nosignal;
 122         }
 123         case LTTNG_CONSUMER_ADD_CHANNEL:
 124         {
 125                 struct lttng_consumer_channel *new_channel;
 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
 134                 DBG("consumer_add_channel %d", msg.u.channel.channel_key);
 135                 new_channel = consumer_allocate_channel(msg.u.channel.channel_key,
 136                                 -1, -1,
 137                                 msg.u.channel.mmap_len,
 138                                 msg.u.channel.max_sb_size,
 139                                 msg.u.channel.nb_init_streams);
 140                 if (new_channel == NULL) {
 141                         lttng_consumer_send_error(ctx, LTTCOMM_CONSUMERD_OUTFD_ERROR);
 142                         goto end_nosignal;
 143                 }
 144                 if (ctx->on_recv_channel != NULL) {
 145                         ret = ctx->on_recv_channel(new_channel);
 146                         if (ret == 0) {
 147                                 consumer_add_channel(new_channel);
 148                         } else if (ret < 0) {
 149                                 goto end_nosignal;
 150                         }
 151                 } else {
 152                         consumer_add_channel(new_channel);
 153                 }
 154                 goto end_nosignal;
 155         }
 156         case LTTNG_CONSUMER_ADD_STREAM:
 157         {
 158                 int fd, stream_pipe;
 159                 struct consumer_relayd_sock_pair *relayd = NULL;
 160                 struct lttng_consumer_stream *new_stream;
 161                 int alloc_ret = 0;
 162
 163                 /* First send a status message before receiving the fds. */
 164                 ret = consumer_send_status_msg(sock, ret_code);
 165                 if (ret < 0) {
 166                         /* Somehow, the session daemon is not responding anymore. */
 167                         goto end_nosignal;
 168                 }
 169
 170                 /* block */
 171                 if (lttng_consumer_poll_socket(consumer_sockpoll) < 0) {
 172                         rcu_read_unlock();
 173                         return -EINTR;
 174                 }
 175
 176                 /* Get stream file descriptor from socket */
 177                 ret = lttcomm_recv_fds_unix_sock(sock, &fd, 1);
 178                 if (ret != sizeof(fd)) {
 179                         lttng_consumer_send_error(ctx, LTTCOMM_CONSUMERD_ERROR_RECV_FD);
 180                         rcu_read_unlock();
 181                         return ret;
 182                 }
 183
 184                 /*
 185                  * Send status code to session daemon only if the recv works. If the
 186                  * above recv() failed, the session daemon is notified through the
 187                  * error socket and the teardown is eventually done.
 188                  */
 189                 ret = consumer_send_status_msg(sock, ret_code);
 190                 if (ret < 0) {
 191                         /* Somehow, the session daemon is not responding anymore. */
 192                         goto end_nosignal;
 193                 }
 194
 195                 new_stream = consumer_allocate_stream(msg.u.stream.channel_key,
 196                                 msg.u.stream.stream_key,
 197                                 fd, fd,
 198                                 msg.u.stream.state,
 199                                 msg.u.stream.mmap_len,
 200                                 msg.u.stream.output,
 201                                 msg.u.stream.path_name,
 202                                 msg.u.stream.uid,
 203                                 msg.u.stream.gid,
 204                                 msg.u.stream.net_index,
 205                                 msg.u.stream.metadata_flag,
 206                                 msg.u.stream.session_id,
 207                                 &alloc_ret);
 208                 if (new_stream == NULL) {
 209                         switch (alloc_ret) {
 210                         case -ENOMEM:
 211                         case -EINVAL:
 212                         default:
 213                                 lttng_consumer_send_error(ctx, LTTCOMM_CONSUMERD_OUTFD_ERROR);
 214                                 break;
 215                         case -ENOENT:
 216                                 /*
 217                                  * We could not find the channel. Can happen if cpu hotplug
 218                                  * happens while tearing down.
 219                                  */
 220                                 DBG3("Could not find channel");
 221                                 break;
 222                         }
 223                         goto end_nosignal;
 224                 }
 225
 226                 /*
 227                  * The buffer flush is done on the session daemon side for the kernel
 228                  * so no need for the stream "hangup_flush_done" variable to be
 229                  * tracked. This is important for a kernel stream since we don't rely
 230                  * on the flush state of the stream to read data. It's not the case for
 231                  * user space tracing.
 232                  */
 233                 new_stream->hangup_flush_done = 0;
 234
 235                 /* The stream is not metadata. Get relayd reference if exists. */
 236                 relayd = consumer_find_relayd(msg.u.stream.net_index);
 237                 if (relayd != NULL) {
 238                         /* Add stream on the relayd */
 239                         pthread_mutex_lock(&relayd->ctrl_sock_mutex);
 240                         ret = relayd_add_stream(&relayd->control_sock,
 241                                         msg.u.stream.name, msg.u.stream.path_name,
 242                                         &new_stream->relayd_stream_id);
 243                         pthread_mutex_unlock(&relayd->ctrl_sock_mutex);
 244                         if (ret < 0) {
 245                                 consumer_del_stream(new_stream, NULL);
 246                                 goto end_nosignal;
 247                         }
 248                 } else if (msg.u.stream.net_index != -1) {
 249                         ERR("Network sequence index %d unknown. Not adding stream.",
 250                                         msg.u.stream.net_index);
 251                         consumer_del_stream(new_stream, NULL);
 252                         goto end_nosignal;
 253                 }
 254
 255                 if (ctx->on_recv_stream) {
 256                         ret = ctx->on_recv_stream(new_stream);
 257                         if (ret < 0) {
 258                                 consumer_del_stream(new_stream, NULL);
 259                                 goto end_nosignal;
 260                         }
 261                 }
 262
 263                 /* Get the right pipe where the stream will be sent. */
 264                 if (new_stream->metadata_flag) {
 265                         stream_pipe = ctx->consumer_metadata_pipe[1];
 266                 } else {
 267                         stream_pipe = ctx->consumer_data_pipe[1];
 268                 }
 269
 270                 do {
 271                         ret = write(stream_pipe, &new_stream, sizeof(new_stream));
 272                 } while (ret < 0 && errno == EINTR);
 273                 if (ret < 0) {
 274                         PERROR("Consumer write %s stream to pipe %d",
 275                                         new_stream->metadata_flag ? "metadata" : "data",
 276                                         stream_pipe);
 277                         consumer_del_stream(new_stream, NULL);
 278                         goto end_nosignal;
 279                 }
 280
 281                 DBG("Kernel consumer ADD_STREAM %s (fd: %d) with relayd id %" PRIu64,
 282                                 msg.u.stream.path_name, fd, new_stream->relayd_stream_id);
 283                 break;
 284         }
 285         case LTTNG_CONSUMER_UPDATE_STREAM:
 286         {
 287                 rcu_read_unlock();
 288                 return -ENOSYS;
 289         }
 290         case LTTNG_CONSUMER_DESTROY_RELAYD:
 291         {
 292                 uint64_t index = msg.u.destroy_relayd.net_seq_idx;
 293                 struct consumer_relayd_sock_pair *relayd;
 294
 295                 DBG("Kernel consumer destroying relayd %" PRIu64, index);
 296
 297                 /* Get relayd reference if exists. */
 298                 relayd = consumer_find_relayd(index);
 299                 if (relayd == NULL) {
 300                         ERR("Unable to find relayd %" PRIu64, index);
 301                         ret_code = LTTNG_ERR_NO_CONSUMER;
 302                 }
 303
 304                 /*
 305                  * Each relayd socket pair has a refcount of stream attached to it
 306                  * which tells if the relayd is still active or not depending on the
 307                  * refcount value.
 308                  *
 309                  * This will set the destroy flag of the relayd object and destroy it
 310                  * if the refcount reaches zero when called.
 311                  *
 312                  * The destroy can happen either here or when a stream fd hangs up.
 313                  */
 314                 if (relayd) {
 315                         consumer_flag_relayd_for_destroy(relayd);
 316                 }
 317
 318                 ret = consumer_send_status_msg(sock, ret_code);
 319                 if (ret < 0) {
 320                         /* Somehow, the session daemon is not responding anymore. */
 321                         goto end_nosignal;
 322                 }
 323
 324                 goto end_nosignal;
 325         }
 326         case LTTNG_CONSUMER_DATA_PENDING:
 327         {
 328                 int32_t ret;
 329                 uint64_t id = msg.u.data_pending.session_id;
 330
 331                 DBG("Kernel consumer data pending command for id %" PRIu64, id);
 332
 333                 ret = consumer_data_pending(id);
 334
 335                 /* Send back returned value to session daemon */
 336                 ret = lttcomm_send_unix_sock(sock, &ret, sizeof(ret));
 337                 if (ret < 0) {
 338                         PERROR("send data pending ret code");
 339                 }
 340
 341                 /*
 342                  * No need to send back a status message since the data pending
 343                  * returned value is the response.
 344                  */
 345                 break;
 346         }
 347         default:
 348                 goto end_nosignal;
 349         }
 350
 351 end_nosignal:
 352         rcu_read_unlock();
 353
 354         /*
 355          * Return 1 to indicate success since the 0 value can be a socket
 356          * shutdown during the recv() or send() call.
 357          */
 358         return 1;
 359 }
 360
 361 /*
 362  * Consume data on a file descriptor and write it on a trace file.
 363  */
 364 ssize_t lttng_kconsumer_read_subbuffer(struct lttng_consumer_stream *stream,
 365                 struct lttng_consumer_local_data *ctx)
 366 {
 367         unsigned long len, subbuf_size, padding;
 368         int err;
 369         ssize_t ret = 0;
 370         int infd = stream->wait_fd;
 371
 372         DBG("In read_subbuffer (infd : %d)", infd);
 373         /* Get the next subbuffer */
 374         err = kernctl_get_next_subbuf(infd);
 375         if (err != 0) {
 376                 ret = err;
 377                 /*
 378                  * This is a debug message even for single-threaded consumer,
 379                  * because poll() have more relaxed criterions than get subbuf,
 380                  * so get_subbuf may fail for short race windows where poll()
 381                  * would issue wakeups.
 382                  */
 383                 DBG("Reserving sub buffer failed (everything is normal, "
 384                                 "it is due to concurrency)");
 385                 goto end;
 386         }
 387
 388         /* Get the full subbuffer size including padding */
 389         err = kernctl_get_padded_subbuf_size(infd, &len);
 390         if (err != 0) {
 391                 errno = -err;
 392                 perror("Getting sub-buffer len failed.");
 393                 ret = err;
 394                 goto end;
 395         }
 396
 397         switch (stream->output) {
 398         case LTTNG_EVENT_SPLICE:
 399
 400                 /*
 401                  * XXX: The lttng-modules splice "actor" does not handle copying
 402                  * partial pages hence only using the subbuffer size without the
 403                  * padding makes the splice fail.
 404                  */
 405                 subbuf_size = len;
 406                 padding = 0;
 407
 408                 /* splice the subbuffer to the tracefile */
 409                 ret = lttng_consumer_on_read_subbuffer_splice(ctx, stream, subbuf_size,
 410                                 padding);
 411                 /*
 412                  * XXX: Splice does not support network streaming so the return value
 413                  * is simply checked against subbuf_size and not like the mmap() op.
 414                  */
 415                 if (ret != subbuf_size) {
 416                         /*
 417                          * display the error but continue processing to try
 418                          * to release the subbuffer
 419                          */
 420                         ERR("Error splicing to tracefile (ret: %zd != len: %lu)",
 421                                         ret, subbuf_size);
 422                 }
 423                 break;
 424         case LTTNG_EVENT_MMAP:
 425                 /* Get subbuffer size without padding */
 426                 err = kernctl_get_subbuf_size(infd, &subbuf_size);
 427                 if (err != 0) {
 428                         errno = -err;
 429                         perror("Getting sub-buffer len failed.");
 430                         ret = err;
 431                         goto end;
 432                 }
 433
 434                 /* Make sure the tracer is not gone mad on us! */
 435                 assert(len >= subbuf_size);
 436
 437                 padding = len - subbuf_size;
 438
 439                 /* write the subbuffer to the tracefile */
 440                 ret = lttng_consumer_on_read_subbuffer_mmap(ctx, stream, subbuf_size,
 441                                 padding);
 442                 /*
 443                  * The mmap operation should write subbuf_size amount of data when
 444                  * network streaming or the full padding (len) size when we are _not_
 445                  * streaming.
 446                  */
 447                 if ((ret != subbuf_size && stream->net_seq_idx != -1) ||
 448                                 (ret != len && stream->net_seq_idx == -1)) {
 449                         /*
 450                          * Display the error but continue processing to try to release the
 451                          * subbuffer
 452                          */
 453                         ERR("Error writing to tracefile "
 454                                         "(ret: %zd != len: %lu != subbuf_size: %lu)",
 455                                         ret, len, subbuf_size);
 456                 }
 457                 break;
 458         default:
 459                 ERR("Unknown output method");
 460                 ret = -1;
 461         }
 462
 463         err = kernctl_put_next_subbuf(infd);
 464         if (err != 0) {
 465                 errno = -err;
 466                 if (errno == EFAULT) {
 467                         perror("Error in unreserving sub buffer\n");
 468                 } else if (errno == EIO) {
 469                         /* Should never happen with newer LTTng versions */
 470                         perror("Reader has been pushed by the writer, last sub-buffer corrupted.");
 471                 }
 472
 473                 ret = -err;
 474                 goto end;
 475         }
 476
 477 end:
 478         return ret;
 479 }
 480
 481 int lttng_kconsumer_on_recv_stream(struct lttng_consumer_stream *stream)
 482 {
 483         int ret;
 484
 485         /* Opening the tracefile in write mode */
 486         if (strlen(stream->path_name) > 0 && stream->net_seq_idx == -1) {
 487                 ret = run_as_open(stream->path_name,
 488                                 O_WRONLY|O_CREAT|O_TRUNC,
 489                                 S_IRWXU|S_IRWXG|S_IRWXO,
 490                                 stream->uid, stream->gid);
 491                 if (ret < 0) {
 492                         ERR("Opening %s", stream->path_name);
 493                         perror("open");
 494                         goto error;
 495                 }
 496                 stream->out_fd = ret;
 497         }
 498
 499         if (stream->output == LTTNG_EVENT_MMAP) {
 500                 /* get the len of the mmap region */
 501                 unsigned long mmap_len;
 502
 503                 ret = kernctl_get_mmap_len(stream->wait_fd, &mmap_len);
 504                 if (ret != 0) {
 505                         errno = -ret;
 506                         perror("kernctl_get_mmap_len");
 507                         goto error_close_fd;
 508                 }
 509                 stream->mmap_len = (size_t) mmap_len;
 510
 511                 stream->mmap_base = mmap(NULL, stream->mmap_len,
 512                                 PROT_READ, MAP_PRIVATE, stream->wait_fd, 0);
 513                 if (stream->mmap_base == MAP_FAILED) {
 514                         perror("Error mmaping");
 515                         ret = -1;
 516                         goto error_close_fd;
 517                 }
 518         }
 519
 520         /* we return 0 to let the library handle the FD internally */
 521         return 0;
 522
 523 error_close_fd:
 524         {
 525                 int err;
 526
 527                 err = close(stream->out_fd);
 528                 assert(!err);
 529         }
 530 error:
 531         return ret;
 532 }
 533
 534 /*
 535  * Check if data is still being extracted from the buffers for a specific
 536  * stream. Consumer data lock MUST be acquired before calling this function
 537  * and the stream lock.
 538  *
 539  * Return 1 if the traced data are still getting read else 0 meaning that the
 540  * data is available for trace viewer reading.
 541  */
 542 int lttng_kconsumer_data_pending(struct lttng_consumer_stream *stream)
 543 {
 544         int ret;
 545
 546         assert(stream);
 547
 548         ret = kernctl_get_next_subbuf(stream->wait_fd);
 549         if (ret == 0) {
 550                 /* There is still data so let's put back this subbuffer. */
 551                 ret = kernctl_put_subbuf(stream->wait_fd);
 552                 assert(ret == 0);
 553                 ret = 1;   /* Data is pending */
 554                 goto end;
 555         }
 556
 557         /* Data is NOT pending and ready to be read. */
 558         ret = 0;
 559
 560 end:
 561         return ret;
 562 }