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 <unistd.h>
  29 #include <sys/stat.h>
  30
  31 #include <common/common.h>
  32 #include <common/kernel-ctl/kernel-ctl.h>
  33 #include <common/sessiond-comm/sessiond-comm.h>
  34 #include <common/sessiond-comm/relayd.h>
  35 #include <common/compat/fcntl.h>
  36 #include <common/relayd/relayd.h>
  37
  38 #include "kernel-consumer.h"
  39
  40 extern struct lttng_consumer_global_data consumer_data;
  41 extern int consumer_poll_timeout;
  42 extern volatile int consumer_quit;
  43
  44 /*
  45  * Take a snapshot for a specific fd
  46  *
  47  * Returns 0 on success, < 0 on error
  48  */
  49 int lttng_kconsumer_take_snapshot(struct lttng_consumer_local_data *ctx,
  50                 struct lttng_consumer_stream *stream)
  51 {
  52         int ret = 0;
  53         int infd = stream->wait_fd;
  54
  55         ret = kernctl_snapshot(infd);
  56         if (ret != 0) {
  57                 errno = -ret;
  58                 perror("Getting sub-buffer snapshot.");
  59         }
  60
  61         return ret;
  62 }
  63
  64 /*
  65  * Get the produced position
  66  *
  67  * Returns 0 on success, < 0 on error
  68  */
  69 int lttng_kconsumer_get_produced_snapshot(
  70                 struct lttng_consumer_local_data *ctx,
  71                 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         struct lttcomm_consumer_msg msg;
  91
  92         ret = lttcomm_recv_unix_sock(sock, &msg, sizeof(msg));
  93         if (ret != sizeof(msg)) {
  94                 lttng_consumer_send_error(ctx, CONSUMERD_ERROR_RECV_CMD);
  95                 return ret;
  96         }
  97         if (msg.cmd_type == LTTNG_CONSUMER_STOP) {
  98                 return -ENOENT;
  99         }
 100
 101         /* relayd needs RCU read-side protection */
 102         rcu_read_lock();
 103
 104         switch (msg.cmd_type) {
 105         case LTTNG_CONSUMER_ADD_RELAYD_SOCKET:
 106         {
 107                 int fd;
 108                 struct consumer_relayd_sock_pair *relayd;
 109
 110                 DBG("Consumer adding relayd socket");
 111
 112                 /* Get relayd reference if exists. */
 113                 relayd = consumer_find_relayd(msg.u.relayd_sock.net_index);
 114                 if (relayd == NULL) {
 115                         /* Not found. Allocate one. */
 116                         relayd = consumer_allocate_relayd_sock_pair(
 117                                         msg.u.relayd_sock.net_index);
 118                         if (relayd == NULL) {
 119                                 lttng_consumer_send_error(ctx, CONSUMERD_OUTFD_ERROR);
 120                                 goto end_nosignal;
 121                         }
 122                 }
 123
 124                 /* Poll on consumer socket. */
 125                 if (lttng_consumer_poll_socket(consumer_sockpoll) < 0) {
 126                         rcu_read_unlock();
 127                         return -EINTR;
 128                 }
 129
 130                 /* Get relayd socket from session daemon */
 131                 ret = lttcomm_recv_fds_unix_sock(sock, &fd, 1);
 132                 if (ret != sizeof(fd)) {
 133                         lttng_consumer_send_error(ctx, CONSUMERD_ERROR_RECV_FD);
 134                         goto end_nosignal;
 135                 }
 136
 137                 /* Copy socket information and received FD */
 138                 switch (msg.u.relayd_sock.type) {
 139                 case LTTNG_STREAM_CONTROL:
 140                         /* Copy received lttcomm socket */
 141                         lttcomm_copy_sock(&relayd->control_sock, &msg.u.relayd_sock.sock);
 142
 143                         ret = lttcomm_create_sock(&relayd->control_sock);
 144                         if (ret < 0) {
 145                                 goto end_nosignal;
 146                         }
 147
 148                         /* Close the created socket fd which is useless */
 149                         close(relayd->control_sock.fd);
 150
 151                         /* Assign new file descriptor */
 152                         relayd->control_sock.fd = fd;
 153                         break;
 154                 case LTTNG_STREAM_DATA:
 155                         /* Copy received lttcomm socket */
 156                         lttcomm_copy_sock(&relayd->data_sock, &msg.u.relayd_sock.sock);
 157                         ret = lttcomm_create_sock(&relayd->data_sock);
 158                         if (ret < 0) {
 159                                 goto end_nosignal;
 160                         }
 161
 162                         /* Close the created socket fd which is useless */
 163                         close(relayd->data_sock.fd);
 164
 165                         /* Assign new file descriptor */
 166                         relayd->data_sock.fd = fd;
 167                         break;
 168                 default:
 169                         ERR("Unknown relayd socket type");
 170                         goto end_nosignal;
 171                 }
 172
 173                 DBG("Consumer %s socket created successfully with net idx %d (fd: %d)",
 174                                 msg.u.relayd_sock.type == LTTNG_STREAM_CONTROL ? "control" : "data",
 175                                 relayd->net_seq_idx, fd);
 176
 177                 /*
 178                  * Add relayd socket pair to consumer data hashtable. If object already
 179                  * exists or on error, the function gracefully returns.
 180                  */
 181                 consumer_add_relayd(relayd);
 182
 183                 goto end_nosignal;
 184         }
 185         case LTTNG_CONSUMER_ADD_CHANNEL:
 186         {
 187                 struct lttng_consumer_channel *new_channel;
 188
 189                 DBG("consumer_add_channel %d", msg.u.channel.channel_key);
 190                 new_channel = consumer_allocate_channel(msg.u.channel.channel_key,
 191                                 -1, -1,
 192                                 msg.u.channel.mmap_len,
 193                                 msg.u.channel.max_sb_size);
 194                 if (new_channel == NULL) {
 195                         lttng_consumer_send_error(ctx, CONSUMERD_OUTFD_ERROR);
 196                         goto end_nosignal;
 197                 }
 198                 if (ctx->on_recv_channel != NULL) {
 199                         ret = ctx->on_recv_channel(new_channel);
 200                         if (ret == 0) {
 201                                 consumer_add_channel(new_channel);
 202                         } else if (ret < 0) {
 203                                 goto end_nosignal;
 204                         }
 205                 } else {
 206                         consumer_add_channel(new_channel);
 207                 }
 208                 goto end_nosignal;
 209         }
 210         case LTTNG_CONSUMER_ADD_STREAM:
 211         {
 212                 int fd;
 213                 struct consumer_relayd_sock_pair *relayd = NULL;
 214                 struct lttng_consumer_stream *new_stream;
 215
 216                 /* block */
 217                 if (lttng_consumer_poll_socket(consumer_sockpoll) < 0) {
 218                         rcu_read_unlock();
 219                         return -EINTR;
 220                 }
 221
 222                 /* Get stream file descriptor from socket */
 223                 ret = lttcomm_recv_fds_unix_sock(sock, &fd, 1);
 224                 if (ret != sizeof(fd)) {
 225                         lttng_consumer_send_error(ctx, CONSUMERD_ERROR_RECV_FD);
 226                         rcu_read_unlock();
 227                         return ret;
 228                 }
 229
 230                 new_stream = consumer_allocate_stream(msg.u.stream.channel_key,
 231                                 msg.u.stream.stream_key,
 232                                 fd, fd,
 233                                 msg.u.stream.state,
 234                                 msg.u.stream.mmap_len,
 235                                 msg.u.stream.output,
 236                                 msg.u.stream.path_name,
 237                                 msg.u.stream.uid,
 238                                 msg.u.stream.gid,
 239                                 msg.u.stream.net_index,
 240                                 msg.u.stream.metadata_flag);
 241                 if (new_stream == NULL) {
 242                         lttng_consumer_send_error(ctx, CONSUMERD_OUTFD_ERROR);
 243                         goto end_nosignal;
 244                 }
 245
 246                 /* The stream is not metadata. Get relayd reference if exists. */
 247                 relayd = consumer_find_relayd(msg.u.stream.net_index);
 248                 if (relayd != NULL) {
 249                         /* Add stream on the relayd */
 250                         pthread_mutex_lock(&relayd->ctrl_sock_mutex);
 251                         ret = relayd_add_stream(&relayd->control_sock,
 252                                         msg.u.stream.name, msg.u.stream.path_name,
 253                                         &new_stream->relayd_stream_id);
 254                         pthread_mutex_unlock(&relayd->ctrl_sock_mutex);
 255                         if (ret < 0) {
 256                                 goto end_nosignal;
 257                         }
 258                 } else if (msg.u.stream.net_index != -1) {
 259                         ERR("Network sequence index %d unknown. Not adding stream.",
 260                                         msg.u.stream.net_index);
 261                         free(new_stream);
 262                         goto end_nosignal;
 263                 }
 264
 265                 if (ctx->on_recv_stream != NULL) {
 266                         ret = ctx->on_recv_stream(new_stream);
 267                         if (ret == 0) {
 268                                 consumer_add_stream(new_stream);
 269                         } else if (ret < 0) {
 270                                 goto end_nosignal;
 271                         }
 272                 } else {
 273                         consumer_add_stream(new_stream);
 274                 }
 275
 276                 DBG("Kernel consumer_add_stream (%d)", fd);
 277                 break;
 278         }
 279         case LTTNG_CONSUMER_UPDATE_STREAM:
 280         {
 281                 rcu_read_unlock();
 282                 return -ENOSYS;
 283         }
 284         case LTTNG_CONSUMER_DESTROY_RELAYD:
 285         {
 286                 struct consumer_relayd_sock_pair *relayd;
 287
 288                 DBG("Kernel consumer destroying relayd %zu",
 289                                 msg.u.destroy_relayd.net_seq_idx);
 290
 291                 /* Get relayd reference if exists. */
 292                 relayd = consumer_find_relayd(msg.u.destroy_relayd.net_seq_idx);
 293                 if (relayd == NULL) {
 294                         ERR("Unable to find relayd %zu", msg.u.destroy_relayd.net_seq_idx);
 295                         goto end_nosignal;
 296                 }
 297
 298                 /* Set destroy flag for this object */
 299                 uatomic_set(&relayd->destroy_flag, 1);
 300
 301                 /* Destroy the relayd if refcount is 0 else set the destroy flag. */
 302                 if (uatomic_read(&relayd->refcount) == 0) {
 303                         consumer_destroy_relayd(relayd);
 304                 }
 305                 goto end_nosignal;
 306         }
 307         default:
 308                 goto end_nosignal;
 309         }
 310
 311         /*
 312          * Wake-up the other end by writing a null byte in the pipe (non-blocking).
 313          * Important note: Because writing into the pipe is non-blocking (and
 314          * therefore we allow dropping wakeup data, as long as there is wakeup data
 315          * present in the pipe buffer to wake up the other end), the other end
 316          * should perform the following sequence for waiting:
 317          *
 318          * 1) empty the pipe (reads).
 319          * 2) perform update operation.
 320          * 3) wait on the pipe (poll).
 321          */
 322         do {
 323                 ret = write(ctx->consumer_poll_pipe[1], "", 1);
 324         } while (ret < 0 && errno == EINTR);
 325 end_nosignal:
 326         rcu_read_unlock();
 327         return 0;
 328 }
 329
 330 /*
 331  * Consume data on a file descriptor and write it on a trace file.
 332  */
 333 ssize_t lttng_kconsumer_read_subbuffer(struct lttng_consumer_stream *stream,
 334                 struct lttng_consumer_local_data *ctx)
 335 {
 336         unsigned long len;
 337         int err;
 338         ssize_t ret = 0;
 339         int infd = stream->wait_fd;
 340
 341         DBG("In read_subbuffer (infd : %d)", infd);
 342         /* Get the next subbuffer */
 343         err = kernctl_get_next_subbuf(infd);
 344         if (err != 0) {
 345                 /*
 346                  * This is a debug message even for single-threaded consumer,
 347                  * because poll() have more relaxed criterions than get subbuf,
 348                  * so get_subbuf may fail for short race windows where poll()
 349                  * would issue wakeups.
 350                  */
 351                 DBG("Reserving sub buffer failed (everything is normal, "
 352                                 "it is due to concurrency)");
 353                 goto end;
 354         }
 355
 356         switch (stream->output) {
 357                 case LTTNG_EVENT_SPLICE:
 358                         /* read the whole subbuffer */
 359                         err = kernctl_get_padded_subbuf_size(infd, &len);
 360                         if (err != 0) {
 361                                 errno = -ret;
 362                                 perror("Getting sub-buffer len failed.");
 363                                 goto end;
 364                         }
 365
 366                         /* splice the subbuffer to the tracefile */
 367                         ret = lttng_consumer_on_read_subbuffer_splice(ctx, stream, len);
 368                         if (ret != len) {
 369                                 /*
 370                                  * display the error but continue processing to try
 371                                  * to release the subbuffer
 372                                  */
 373                                 ERR("Error splicing to tracefile (ret: %ld != len: %ld)",
 374                                                 ret, len);
 375                         }
 376
 377                         break;
 378                 case LTTNG_EVENT_MMAP:
 379                         /* read the used subbuffer size */
 380                         err = kernctl_get_padded_subbuf_size(infd, &len);
 381                         if (err != 0) {
 382                                 errno = -ret;
 383                                 perror("Getting sub-buffer len failed.");
 384                                 goto end;
 385                         }
 386                         /* write the subbuffer to the tracefile */
 387                         ret = lttng_consumer_on_read_subbuffer_mmap(ctx, stream, len);
 388                         if (ret != len) {
 389                                 /*
 390                                  * display the error but continue processing to try
 391                                  * to release the subbuffer
 392                                  */
 393                                 ERR("Error writing to tracefile");
 394                         }
 395                         break;
 396                 default:
 397                         ERR("Unknown output method");
 398                         ret = -1;
 399         }
 400
 401         err = kernctl_put_next_subbuf(infd);
 402         if (err != 0) {
 403                 errno = -ret;
 404                 if (errno == EFAULT) {
 405                         perror("Error in unreserving sub buffer\n");
 406                 } else if (errno == EIO) {
 407                         /* Should never happen with newer LTTng versions */
 408                         perror("Reader has been pushed by the writer, last sub-buffer corrupted.");
 409                 }
 410                 goto end;
 411         }
 412
 413 end:
 414         return ret;
 415 }
 416
 417 int lttng_kconsumer_on_recv_stream(struct lttng_consumer_stream *stream)
 418 {
 419         int ret;
 420
 421         /* Opening the tracefile in write mode */
 422         if (strlen(stream->path_name) > 0 && stream->net_seq_idx == -1) {
 423                 ret = run_as_open(stream->path_name,
 424                                 O_WRONLY|O_CREAT|O_TRUNC,
 425                                 S_IRWXU|S_IRWXG|S_IRWXO,
 426                                 stream->uid, stream->gid);
 427                 if (ret < 0) {
 428                         ERR("Opening %s", stream->path_name);
 429                         perror("open");
 430                         goto error;
 431                 }
 432                 stream->out_fd = ret;
 433         }
 434
 435         if (stream->output == LTTNG_EVENT_MMAP) {
 436                 /* get the len of the mmap region */
 437                 unsigned long mmap_len;
 438
 439                 ret = kernctl_get_mmap_len(stream->wait_fd, &mmap_len);
 440                 if (ret != 0) {
 441                         errno = -ret;
 442                         perror("kernctl_get_mmap_len");
 443                         goto error_close_fd;
 444                 }
 445                 stream->mmap_len = (size_t) mmap_len;
 446
 447                 stream->mmap_base = mmap(NULL, stream->mmap_len,
 448                                 PROT_READ, MAP_PRIVATE, stream->wait_fd, 0);
 449                 if (stream->mmap_base == MAP_FAILED) {
 450                         perror("Error mmaping");
 451                         ret = -1;
 452                         goto error_close_fd;
 453                 }
 454         }
 455
 456         /* we return 0 to let the library handle the FD internally */
 457         return 0;
 458
 459 error_close_fd:
 460         {
 461                 int err;
 462
 463                 err = close(stream->out_fd);
 464                 assert(!err);
 465         }
 466 error:
 467         return ret;
 468 }
 469