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