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         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, CONSUMERD_ERROR_RECV_CMD);
  96                 return ret;
  97         }
  98         if (msg.cmd_type == LTTNG_CONSUMER_STOP) {
  99                 return -ENOENT;
 100         }
 101
 102         /* relayd needs RCU read-side protection */
 103         rcu_read_lock();
 104
 105         switch (msg.cmd_type) {
 106         case LTTNG_CONSUMER_ADD_RELAYD_SOCKET:
 107         {
 108                 int fd;
 109                 struct consumer_relayd_sock_pair *relayd;
 110
 111                 DBG("Consumer adding relayd socket");
 112
 113                 /* Get relayd reference if exists. */
 114                 relayd = consumer_find_relayd(msg.u.relayd_sock.net_index);
 115                 if (relayd == NULL) {
 116                         /* Not found. Allocate one. */
 117                         relayd = consumer_allocate_relayd_sock_pair(
 118                                         msg.u.relayd_sock.net_index);
 119                         if (relayd == NULL) {
 120                                 lttng_consumer_send_error(ctx, CONSUMERD_OUTFD_ERROR);
 121                                 goto end_nosignal;
 122                         }
 123                 }
 124
 125                 /* Poll on consumer socket. */
 126                 if (lttng_consumer_poll_socket(consumer_sockpoll) < 0) {
 127                         rcu_read_unlock();
 128                         return -EINTR;
 129                 }
 130
 131                 /* Get relayd socket from session daemon */
 132                 ret = lttcomm_recv_fds_unix_sock(sock, &fd, 1);
 133                 if (ret != sizeof(fd)) {
 134                         lttng_consumer_send_error(ctx, CONSUMERD_ERROR_RECV_FD);
 135                         goto end_nosignal;
 136                 }
 137
 138                 /* Copy socket information and received FD */
 139                 switch (msg.u.relayd_sock.type) {
 140                 case LTTNG_STREAM_CONTROL:
 141                         /* Copy received lttcomm socket */
 142                         lttcomm_copy_sock(&relayd->control_sock, &msg.u.relayd_sock.sock);
 143
 144                         ret = lttcomm_create_sock(&relayd->control_sock);
 145                         if (ret < 0) {
 146                                 goto end_nosignal;
 147                         }
 148
 149                         /* Close the created socket fd which is useless */
 150                         close(relayd->control_sock.fd);
 151
 152                         /* Assign new file descriptor */
 153                         relayd->control_sock.fd = fd;
 154                         break;
 155                 case LTTNG_STREAM_DATA:
 156                         /* Copy received lttcomm socket */
 157                         lttcomm_copy_sock(&relayd->data_sock, &msg.u.relayd_sock.sock);
 158                         ret = lttcomm_create_sock(&relayd->data_sock);
 159                         if (ret < 0) {
 160                                 goto end_nosignal;
 161                         }
 162
 163                         /* Close the created socket fd which is useless */
 164                         close(relayd->data_sock.fd);
 165
 166                         /* Assign new file descriptor */
 167                         relayd->data_sock.fd = fd;
 168                         break;
 169                 default:
 170                         ERR("Unknown relayd socket type");
 171                         goto end_nosignal;
 172                 }
 173
 174                 DBG("Consumer %s socket created successfully with net idx %d (fd: %d)",
 175                                 msg.u.relayd_sock.type == LTTNG_STREAM_CONTROL ? "control" : "data",
 176                                 relayd->net_seq_idx, fd);
 177
 178                 /*
 179                  * Add relayd socket pair to consumer data hashtable. If object already
 180                  * exists or on error, the function gracefully returns.
 181                  */
 182                 consumer_add_relayd(relayd);
 183
 184                 goto end_nosignal;
 185         }
 186         case LTTNG_CONSUMER_ADD_CHANNEL:
 187         {
 188                 struct lttng_consumer_channel *new_channel;
 189
 190                 DBG("consumer_add_channel %d", msg.u.channel.channel_key);
 191                 new_channel = consumer_allocate_channel(msg.u.channel.channel_key,
 192                                 -1, -1,
 193                                 msg.u.channel.mmap_len,
 194                                 msg.u.channel.max_sb_size);
 195                 if (new_channel == NULL) {
 196                         lttng_consumer_send_error(ctx, CONSUMERD_OUTFD_ERROR);
 197                         goto end_nosignal;
 198                 }
 199                 if (ctx->on_recv_channel != NULL) {
 200                         ret = ctx->on_recv_channel(new_channel);
 201                         if (ret == 0) {
 202                                 consumer_add_channel(new_channel);
 203                         } else if (ret < 0) {
 204                                 goto end_nosignal;
 205                         }
 206                 } else {
 207                         consumer_add_channel(new_channel);
 208                 }
 209                 goto end_nosignal;
 210         }
 211         case LTTNG_CONSUMER_ADD_STREAM:
 212         {
 213                 int fd;
 214                 struct consumer_relayd_sock_pair *relayd = NULL;
 215                 struct lttng_consumer_stream *new_stream;
 216
 217                 /* block */
 218                 if (lttng_consumer_poll_socket(consumer_sockpoll) < 0) {
 219                         rcu_read_unlock();
 220                         return -EINTR;
 221                 }
 222
 223                 /* Get stream file descriptor from socket */
 224                 ret = lttcomm_recv_fds_unix_sock(sock, &fd, 1);
 225                 if (ret != sizeof(fd)) {
 226                         lttng_consumer_send_error(ctx, CONSUMERD_ERROR_RECV_FD);
 227                         rcu_read_unlock();
 228                         return ret;
 229                 }
 230
 231                 new_stream = consumer_allocate_stream(msg.u.stream.channel_key,
 232                                 msg.u.stream.stream_key,
 233                                 fd, fd,
 234                                 msg.u.stream.state,
 235                                 msg.u.stream.mmap_len,
 236                                 msg.u.stream.output,
 237                                 msg.u.stream.path_name,
 238                                 msg.u.stream.uid,
 239                                 msg.u.stream.gid,
 240                                 msg.u.stream.net_index,
 241                                 msg.u.stream.metadata_flag);
 242                 if (new_stream == NULL) {
 243                         lttng_consumer_send_error(ctx, CONSUMERD_OUTFD_ERROR);
 244                         goto end_nosignal;
 245                 }
 246
 247                 /* The stream is not metadata. Get relayd reference if exists. */
 248                 relayd = consumer_find_relayd(msg.u.stream.net_index);
 249                 if (relayd != NULL) {
 250                         /* Add stream on the relayd */
 251                         pthread_mutex_lock(&relayd->ctrl_sock_mutex);
 252                         ret = relayd_add_stream(&relayd->control_sock,
 253                                         msg.u.stream.name, msg.u.stream.path_name,
 254                                         &new_stream->relayd_stream_id);
 255                         pthread_mutex_unlock(&relayd->ctrl_sock_mutex);
 256                         if (ret < 0) {
 257                                 goto end_nosignal;
 258                         }
 259                 } else if (msg.u.stream.net_index != -1) {
 260                         ERR("Network sequence index %d unknown. Not adding stream.",
 261                                         msg.u.stream.net_index);
 262                         free(new_stream);
 263                         goto end_nosignal;
 264                 }
 265
 266                 if (ctx->on_recv_stream != NULL) {
 267                         ret = ctx->on_recv_stream(new_stream);
 268                         if (ret == 0) {
 269                                 consumer_add_stream(new_stream);
 270                         } else if (ret < 0) {
 271                                 goto end_nosignal;
 272                         }
 273                 } else {
 274                         consumer_add_stream(new_stream);
 275                 }
 276
 277                 DBG("Kernel consumer_add_stream (%d)", fd);
 278                 break;
 279         }
 280         case LTTNG_CONSUMER_UPDATE_STREAM:
 281         {
 282                 rcu_read_unlock();
 283                 return -ENOSYS;
 284         }
 285         case LTTNG_CONSUMER_DESTROY_RELAYD:
 286         {
 287                 struct consumer_relayd_sock_pair *relayd;
 288
 289                 DBG("Kernel consumer destroying relayd %" PRIu64,
 290                                 msg.u.destroy_relayd.net_seq_idx);
 291
 292                 /* Get relayd reference if exists. */
 293                 relayd = consumer_find_relayd(msg.u.destroy_relayd.net_seq_idx);
 294                 if (relayd == NULL) {
 295                         ERR("Unable to find relayd %" PRIu64,
 296                                         msg.u.destroy_relayd.net_seq_idx);
 297                         goto end_nosignal;
 298                 }
 299
 300                 /* Set destroy flag for this object */
 301                 uatomic_set(&relayd->destroy_flag, 1);
 302
 303                 /* Destroy the relayd if refcount is 0 else set the destroy flag. */
 304                 if (uatomic_read(&relayd->refcount) == 0) {
 305                         consumer_destroy_relayd(relayd);
 306                 }
 307                 goto end_nosignal;
 308         }
 309         default:
 310                 goto end_nosignal;
 311         }
 312
 313         /*
 314          * Wake-up the other end by writing a null byte in the pipe (non-blocking).
 315          * Important note: Because writing into the pipe is non-blocking (and
 316          * therefore we allow dropping wakeup data, as long as there is wakeup data
 317          * present in the pipe buffer to wake up the other end), the other end
 318          * should perform the following sequence for waiting:
 319          *
 320          * 1) empty the pipe (reads).
 321          * 2) perform update operation.
 322          * 3) wait on the pipe (poll).
 323          */
 324         do {
 325                 ret = write(ctx->consumer_poll_pipe[1], "", 1);
 326         } while (ret < 0 && errno == EINTR);
 327 end_nosignal:
 328         rcu_read_unlock();
 329         return 0;
 330 }
 331
 332 /*
 333  * Consume data on a file descriptor and write it on a trace file.
 334  */
 335 ssize_t lttng_kconsumer_read_subbuffer(struct lttng_consumer_stream *stream,
 336                 struct lttng_consumer_local_data *ctx)
 337 {
 338         unsigned long len;
 339         int err;
 340         ssize_t ret = 0;
 341         int infd = stream->wait_fd;
 342
 343         DBG("In read_subbuffer (infd : %d)", infd);
 344         /* Get the next subbuffer */
 345         err = kernctl_get_next_subbuf(infd);
 346         if (err != 0) {
 347                 /*
 348                  * This is a debug message even for single-threaded consumer,
 349                  * because poll() have more relaxed criterions than get subbuf,
 350                  * so get_subbuf may fail for short race windows where poll()
 351                  * would issue wakeups.
 352                  */
 353                 DBG("Reserving sub buffer failed (everything is normal, "
 354                                 "it is due to concurrency)");
 355                 goto end;
 356         }
 357
 358         switch (stream->output) {
 359                 case LTTNG_EVENT_SPLICE:
 360                         /* read the whole subbuffer */
 361                         err = kernctl_get_padded_subbuf_size(infd, &len);
 362                         if (err != 0) {
 363                                 errno = -ret;
 364                                 perror("Getting sub-buffer len failed.");
 365                                 goto end;
 366                         }
 367
 368                         /* splice the subbuffer to the tracefile */
 369                         ret = lttng_consumer_on_read_subbuffer_splice(ctx, stream, len);
 370                         if (ret != len) {
 371                                 /*
 372                                  * display the error but continue processing to try
 373                                  * to release the subbuffer
 374                                  */
 375                                 ERR("Error splicing to tracefile (ret: %zd != len: %lu)",
 376                                                 ret, len);
 377                         }
 378
 379                         break;
 380                 case LTTNG_EVENT_MMAP:
 381                         /* read the used subbuffer size */
 382                         err = kernctl_get_padded_subbuf_size(infd, &len);
 383                         if (err != 0) {
 384                                 errno = -ret;
 385                                 perror("Getting sub-buffer len failed.");
 386                                 goto end;
 387                         }
 388                         /* write the subbuffer to the tracefile */
 389                         ret = lttng_consumer_on_read_subbuffer_mmap(ctx, stream, len);
 390                         if (ret != len) {
 391                                 /*
 392                                  * display the error but continue processing to try
 393                                  * to release the subbuffer
 394                                  */
 395                                 ERR("Error writing to tracefile");
 396                         }
 397                         break;
 398                 default:
 399                         ERR("Unknown output method");
 400                         ret = -1;
 401         }
 402
 403         err = kernctl_put_next_subbuf(infd);
 404         if (err != 0) {
 405                 errno = -ret;
 406                 if (errno == EFAULT) {
 407                         perror("Error in unreserving sub buffer\n");
 408                 } else if (errno == EIO) {
 409                         /* Should never happen with newer LTTng versions */
 410                         perror("Reader has been pushed by the writer, last sub-buffer corrupted.");
 411                 }
 412                 goto end;
 413         }
 414
 415 end:
 416         return ret;
 417 }
 418
 419 int lttng_kconsumer_on_recv_stream(struct lttng_consumer_stream *stream)
 420 {
 421         int ret;
 422
 423         /* Opening the tracefile in write mode */
 424         if (strlen(stream->path_name) > 0 && stream->net_seq_idx == -1) {
 425                 ret = run_as_open(stream->path_name,
 426                                 O_WRONLY|O_CREAT|O_TRUNC,
 427                                 S_IRWXU|S_IRWXG|S_IRWXO,
 428                                 stream->uid, stream->gid);
 429                 if (ret < 0) {
 430                         ERR("Opening %s", stream->path_name);
 431                         perror("open");
 432                         goto error;
 433                 }
 434                 stream->out_fd = ret;
 435         }
 436
 437         if (stream->output == LTTNG_EVENT_MMAP) {
 438                 /* get the len of the mmap region */
 439                 unsigned long mmap_len;
 440
 441                 ret = kernctl_get_mmap_len(stream->wait_fd, &mmap_len);
 442                 if (ret != 0) {
 443                         errno = -ret;
 444                         perror("kernctl_get_mmap_len");
 445                         goto error_close_fd;
 446                 }
 447                 stream->mmap_len = (size_t) mmap_len;
 448
 449                 stream->mmap_base = mmap(NULL, stream->mmap_len,
 450                                 PROT_READ, MAP_PRIVATE, stream->wait_fd, 0);
 451                 if (stream->mmap_base == MAP_FAILED) {
 452                         perror("Error mmaping");
 453                         ret = -1;
 454                         goto error_close_fd;
 455                 }
 456         }
 457
 458         /* we return 0 to let the library handle the FD internally */
 459         return 0;
 460
 461 error_close_fd:
 462         {
 463                 int err;
 464
 465                 err = close(stream->out_fd);
 466                 assert(!err);
 467         }
 468 error:
 469         return ret;
 470 }
 471