ltt-control/lttd/lttd.c

   1 /* lttd
   2  *
   3  * Linux Trace Toolkit Daemon
   4  *
   5  * This is a simple daemon that reads a few relayfs channels and save them in a
   6  * trace.
   7  *
   8  *
   9  * Copyright 2005 -
  10  *      Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
  11  */
  12
  13 #ifdef HAVE_CONFIG_H
  14 #include <config.h>
  15 #endif
  16
  17 #define _REENTRANT
  18 #define _GNU_SOURCE
  19 #include <features.h>
  20 #include <stdio.h>
  21 #include <unistd.h>
  22 #include <errno.h>
  23 #include <sys/types.h>
  24 #include <sys/stat.h>
  25 #include <stdlib.h>
  26 #include <dirent.h>
  27 #include <string.h>
  28 #include <fcntl.h>
  29 #include <sys/poll.h>
  30 #include <sys/mman.h>
  31 #include <signal.h>
  32 #include <pthread.h>
  33
  34 /* Relayfs IOCTL */
  35 #include <asm/ioctl.h>
  36 #include <asm/types.h>
  37
  38 /* Get the next sub buffer that can be read. */
  39 #define RELAYFS_GET_SUBBUF        _IOR(0xF4, 0x00,__u32)
  40 /* Release the oldest reserved (by "get") sub buffer. */
  41 #define RELAYFS_PUT_SUBBUF        _IOW(0xF4, 0x01,__u32)
  42 /* returns the number of sub buffers in the per cpu channel. */
  43 #define RELAYFS_GET_N_SUBBUFS     _IOR(0xF4, 0x02,__u32)
  44 /* returns the size of the sub buffers. */
  45 #define RELAYFS_GET_SUBBUF_SIZE   _IOR(0xF4, 0x03,__u32)
  46
  47
  48
  49 enum {
  50         GET_SUBBUF,
  51         PUT_SUBBUF,
  52         GET_N_BUBBUFS,
  53         GET_SUBBUF_SIZE
  54 };
  55
  56 struct fd_pair {
  57         int channel;
  58         int trace;
  59         unsigned int n_subbufs;
  60         unsigned int subbuf_size;
  61         void *mmap;
  62         pthread_mutex_t mutex;
  63 };
  64
  65 struct channel_trace_fd {
  66         struct fd_pair *pair;
  67         int num_pairs;
  68 };
  69
  70 static char *trace_name = NULL;
  71 static char *channel_name = NULL;
  72 static int      daemon_mode = 0;
  73 static int      append_mode = 0;
  74 static unsigned long num_threads = 1;
  75 volatile static int     quit_program = 0;       /* For signal handler */
  76
  77 /* Args :
  78  *
  79  * -t directory         Directory name of the trace to write to. Will be created.
  80  * -c directory         Root directory of the relayfs trace channels.
  81  * -d                   Run in background (daemon).
  82  * -a                                                   Trace append mode.
  83  * -s                                                   Send SIGUSR1 to parent when ready for IO.
  84  */
  85 void show_arguments(void)
  86 {
  87         printf("Please use the following arguments :\n");
  88         printf("\n");
  89         printf("-t directory  Directory name of the trace to write to.\n"
  90                                  "              It will be created.\n");
  91         printf("-c directory  Root directory of the relayfs trace channels.\n");
  92         printf("-d            Run in background (daemon).\n");
  93         printf("-a            Append to an possibly existing trace.\n");
  94         printf("-N            Number of threads to start.\n");
  95         printf("\n");
  96 }
  97
  98
  99 /* parse_arguments
 100  *
 101  * Parses the command line arguments.
 102  *
 103  * Returns 1 if the arguments were correct, but doesn't ask for program
 104  * continuation. Returns -1 if the arguments are incorrect, or 0 if OK.
 105  */
 106 int parse_arguments(int argc, char **argv)
 107 {
 108         int ret = 0;
 109         int argn = 1;
 110
 111         if(argc == 2) {
 112                 if(strcmp(argv[1], "-h") == 0) {
 113                         return 1;
 114                 }
 115         }
 116
 117         while(argn < argc) {
 118
 119                 switch(argv[argn][0]) {
 120                         case '-':
 121                                 switch(argv[argn][1]) {
 122                                         case 't':
 123                                                 if(argn+1 < argc) {
 124                                                         trace_name = argv[argn+1];
 125                                                         argn++;
 126                                                 }
 127                                                 break;
 128                                         case 'c':
 129                                                 if(argn+1 < argc) {
 130                                                         channel_name = argv[argn+1];
 131                                                         argn++;
 132                                                 }
 133                                                 break;
 134                                         case 'd':
 135                                                 daemon_mode = 1;
 136                                                 break;
 137                                         case 'a':
 138                                                 append_mode = 1;
 139                                                 break;
 140                                         case 'N':
 141                                                 if(argn+1 < argc) {
 142                                                         num_threads = strtoul(argv[argn+1], NULL, 0);
 143                                                         argn++;
 144                                                 }
 145                                                 break;
 146                                         default:
 147                                                 printf("Invalid argument '%s'.\n", argv[argn]);
 148                                                 printf("\n");
 149                                                 ret = -1;
 150                                 }
 151                                 break;
 152                         default:
 153                                 printf("Invalid argument '%s'.\n", argv[argn]);
 154                                 printf("\n");
 155                                 ret = -1;
 156                 }
 157                 argn++;
 158         }
 159
 160         if(trace_name == NULL) {
 161                 printf("Please specify a trace name.\n");
 162                 printf("\n");
 163                 ret = -1;
 164         }
 165
 166         if(channel_name == NULL) {
 167                 printf("Please specify a channel name.\n");
 168                 printf("\n");
 169                 ret = -1;
 170         }
 171
 172         return ret;
 173 }
 174
 175 void show_info(void)
 176 {
 177         printf("Linux Trace Toolkit Trace Daemon\n");
 178         printf("\n");
 179         printf("Reading from relayfs directory : %s\n", channel_name);
 180         printf("Writing to trace directory : %s\n", trace_name);
 181         printf("\n");
 182 }
 183
 184
 185 /* signal handling */
 186
 187 static void handler(int signo)
 188 {
 189         printf("Signal %d received : exiting cleanly\n", signo);
 190         quit_program = 1;
 191 }
 192
 193
 194
 195 int open_channel_trace_pairs(char *subchannel_name, char *subtrace_name,
 196                 struct channel_trace_fd *fd_pairs)
 197 {
 198         DIR *channel_dir = opendir(subchannel_name);
 199         struct dirent *entry;
 200         struct stat stat_buf;
 201         int ret;
 202         char path_channel[PATH_MAX];
 203         int path_channel_len;
 204         char *path_channel_ptr;
 205         char path_trace[PATH_MAX];
 206         int path_trace_len;
 207         char *path_trace_ptr;
 208   int open_ret = 0;
 209
 210         if(channel_dir == NULL) {
 211                 perror(subchannel_name);
 212                 open_ret = ENOENT;
 213     goto end;
 214         }
 215
 216         printf("Creating trace subdirectory %s\n", subtrace_name);
 217         ret = mkdir(subtrace_name, S_IRWXU|S_IRWXG|S_IRWXO);
 218         if(ret == -1) {
 219                 if(errno != EEXIST) {
 220                         perror(subtrace_name);
 221       open_ret = -1;
 222                         goto end;
 223                 }
 224         }
 225
 226         strncpy(path_channel, subchannel_name, PATH_MAX-1);
 227         path_channel_len = strlen(path_channel);
 228         path_channel[path_channel_len] = '/';
 229         path_channel_len++;
 230         path_channel_ptr = path_channel + path_channel_len;
 231
 232         strncpy(path_trace, subtrace_name, PATH_MAX-1);
 233         path_trace_len = strlen(path_trace);
 234         path_trace[path_trace_len] = '/';
 235         path_trace_len++;
 236         path_trace_ptr = path_trace + path_trace_len;
 237
 238         while((entry = readdir(channel_dir)) != NULL) {
 239
 240                 if(entry->d_name[0] == '.') continue;
 241
 242                 strncpy(path_channel_ptr, entry->d_name, PATH_MAX - path_channel_len);
 243                 strncpy(path_trace_ptr, entry->d_name, PATH_MAX - path_trace_len);
 244
 245                 ret = stat(path_channel, &stat_buf);
 246                 if(ret == -1) {
 247                         perror(path_channel);
 248                         continue;
 249                 }
 250
 251                 printf("Channel file : %s\n", path_channel);
 252
 253                 if(S_ISDIR(stat_buf.st_mode)) {
 254
 255                         printf("Entering channel subdirectory...\n");
 256                         ret = open_channel_trace_pairs(path_channel, path_trace, fd_pairs);
 257                         if(ret < 0) continue;
 258                 } else if(S_ISREG(stat_buf.st_mode)) {
 259                         printf("Opening file.\n");
 260
 261                         fd_pairs->pair = realloc(fd_pairs->pair,
 262                                         ++fd_pairs->num_pairs * sizeof(struct fd_pair));
 263
 264                         /* Open the channel in read mode */
 265                         fd_pairs->pair[fd_pairs->num_pairs-1].channel =
 266                                 open(path_channel, O_RDONLY | O_NONBLOCK);
 267                         if(fd_pairs->pair[fd_pairs->num_pairs-1].channel == -1) {
 268                                 perror(path_channel);
 269                                 fd_pairs->num_pairs--;
 270                                 continue;
 271                         }
 272                         /* Open the trace in write mode, only append if append_mode */
 273                         ret = stat(path_trace, &stat_buf);
 274                         if(ret == 0) {
 275                                 if(append_mode) {
 276                                         printf("Appending to file %s as requested\n", path_trace);
 277
 278                                         fd_pairs->pair[fd_pairs->num_pairs-1].trace =
 279                                                 open(path_trace, O_WRONLY|O_APPEND,
 280                                                                 S_IRWXU|S_IRWXG|S_IRWXO);
 281
 282                                         if(fd_pairs->pair[fd_pairs->num_pairs-1].trace == -1) {
 283                                                 perror(path_trace);
 284                                         }
 285                                 } else {
 286                                         printf("File %s exists, cannot open. Try append mode.\n", path_trace);
 287                                         open_ret = -1;
 288           goto end;
 289                                 }
 290                         } else {
 291                                 if(errno == ENOENT) {
 292                                         fd_pairs->pair[fd_pairs->num_pairs-1].trace =
 293                                                 open(path_trace, O_WRONLY|O_CREAT|O_EXCL,
 294                                                                 S_IRWXU|S_IRWXG|S_IRWXO);
 295                                         if(fd_pairs->pair[fd_pairs->num_pairs-1].trace == -1) {
 296                                                 perror(path_trace);
 297                                         }
 298                                 }
 299                         }
 300                 }
 301         }
 302
 303 end:
 304         closedir(channel_dir);
 305
 306         return open_ret;
 307 }
 308
 309
 310 int read_subbuffer(struct fd_pair *pair)
 311 {
 312         unsigned int    consumed_old;
 313         int err, ret=0;
 314
 315
 316         err = ioctl(pair->channel, RELAYFS_GET_SUBBUF,
 317                                                                 &consumed_old);
 318         printf("cookie : %u\n", consumed_old);
 319         if(err != 0) {
 320                 ret = errno;
 321                 perror("Reserving sub buffer failed (everything is normal)");
 322                 goto get_error;
 323         }
 324
 325         err = TEMP_FAILURE_RETRY(write(pair->trace,
 326                                 pair->mmap
 327                                         + (consumed_old & ((pair->n_subbufs * pair->subbuf_size)-1)),
 328                                 pair->subbuf_size));
 329
 330         if(err < 0) {
 331                 ret = errno;
 332                 perror("Error in writing to file");
 333                 goto write_error;
 334         }
 335 #if 0
 336         err = fsync(pair->trace);
 337         if(err < 0) {
 338                 ret = errno;
 339                 perror("Error in writing to file");
 340                 goto write_error;
 341         }
 342 #endif //0
 343 write_error:
 344         err = ioctl(pair->channel, RELAYFS_PUT_SUBBUF, &consumed_old);
 345         if(err != 0) {
 346                 ret = errno;
 347                 if(errno == -EFAULT) {
 348                         perror("Error in unreserving sub buffer\n");
 349                 } else if(errno == -EIO) {
 350                         perror("Reader has been pushed by the writer, last subbuffer corrupted.");
 351                         /* FIXME : we may delete the last written buffer if we wish. */
 352                 }
 353                 goto get_error;
 354         }
 355
 356 get_error:
 357         return ret;
 358 }
 359
 360
 361
 362 int map_channels(struct channel_trace_fd *fd_pairs)
 363 {
 364         int i,j;
 365         int ret=0;
 366
 367         if(fd_pairs->num_pairs <= 0) {
 368                 printf("No channel to read\n");
 369                 goto end;
 370         }
 371
 372         /* Get the subbuf sizes and number */
 373
 374         for(i=0;i<fd_pairs->num_pairs;i++) {
 375                 struct fd_pair *pair = &fd_pairs->pair[i];
 376
 377                 ret = ioctl(pair->channel, RELAYFS_GET_N_SUBBUFS,
 378                                                         &pair->n_subbufs);
 379                 if(ret != 0) {
 380                         perror("Error in getting the number of subbuffers");
 381                         goto end;
 382                 }
 383                 ret = ioctl(pair->channel, RELAYFS_GET_SUBBUF_SIZE,
 384                                                         &pair->subbuf_size);
 385                 if(ret != 0) {
 386                         perror("Error in getting the size of the subbuffers");
 387                         goto end;
 388                 }
 389                 ret = pthread_mutex_init(&pair->mutex, NULL);   /* Fast mutex */
 390                 if(ret != 0) {
 391                         perror("Error in mutex init");
 392                         goto end;
 393                 }
 394         }
 395
 396         /* Mmap each FD */
 397         for(i=0;i<fd_pairs->num_pairs;i++) {
 398                 struct fd_pair *pair = &fd_pairs->pair[i];
 399
 400                 pair->mmap = mmap(0, pair->subbuf_size * pair->n_subbufs, PROT_READ,
 401                                 MAP_SHARED, pair->channel, 0);
 402                 if(pair->mmap == MAP_FAILED) {
 403                         perror("Mmap error");
 404                         goto munmap;
 405                 }
 406         }
 407
 408         goto end; /* success */
 409
 410         /* Error handling */
 411         /* munmap only the successfully mmapped indexes */
 412 munmap:
 413                 /* Munmap each FD */
 414         for(j=0;j<i;j++) {
 415                 struct fd_pair *pair = &fd_pairs->pair[j];
 416                 int err_ret;
 417
 418                 err_ret = munmap(pair->mmap, pair->subbuf_size * pair->n_subbufs);
 419                 if(err_ret != 0) {
 420                         perror("Error in munmap");
 421                 }
 422                 ret |= err_ret;
 423         }
 424
 425 end:
 426         return ret;
 427
 428
 429 }
 430
 431
 432 int unmap_channels(struct channel_trace_fd *fd_pairs)
 433 {
 434         int j;
 435         int ret=0;
 436
 437         /* Munmap each FD */
 438         for(j=0;j<fd_pairs->num_pairs;j++) {
 439                 struct fd_pair *pair = &fd_pairs->pair[j];
 440                 int err_ret;
 441
 442                 err_ret = munmap(pair->mmap, pair->subbuf_size * pair->n_subbufs);
 443                 if(err_ret != 0) {
 444                         perror("Error in munmap");
 445                 }
 446                 ret |= err_ret;
 447                 err_ret = pthread_mutex_destroy(&pair->mutex);
 448                 if(err_ret != 0) {
 449                         perror("Error in mutex destroy");
 450                 }
 451                 ret |= err_ret;
 452         }
 453
 454         return ret;
 455 }
 456
 457
 458 /* read_channels
 459  *
 460  * Thread worker.
 461  *
 462  * Read the relayfs channels and write them in the paired tracefiles.
 463  *
 464  * @fd_pairs : paired channels and trace files.
 465  *
 466  * returns (void*)0 on success, (void*)-1 on error.
 467  *
 468  * Note that the high priority polled channels are consumed first. We then poll
 469  * again to see if these channels are still in priority. Only when no
 470  * high priority channel is left, we start reading low priority channels.
 471  *
 472  * Note that a channel is considered high priority when the buffer is almost
 473  * full.
 474  */
 475
 476 void * read_channels(void *arg)
 477 {
 478         struct pollfd *pollfd;
 479         int i,j;
 480         int num_rdy, num_hup;
 481         int high_prio;
 482         int ret = 0;
 483         struct channel_trace_fd *fd_pairs = (struct channel_trace_fd *)arg;
 484
 485         /* Start polling the FD */
 486
 487         pollfd = malloc(fd_pairs->num_pairs * sizeof(struct pollfd));
 488
 489         /* Note : index in pollfd is the same index as fd_pair->pair */
 490         for(i=0;i<fd_pairs->num_pairs;i++) {
 491                 pollfd[i].fd = fd_pairs->pair[i].channel;
 492                 pollfd[i].events = POLLIN|POLLPRI;
 493         }
 494
 495         while(1) {
 496                 high_prio = 0;
 497                 num_hup = 0;
 498 #ifdef DEBUG
 499                 printf("Press a key for next poll...\n");
 500                 char buf[1];
 501                 read(STDIN_FILENO, &buf, 1);
 502                 printf("Next poll (polling %d fd) :\n", fd_pairs->num_pairs);
 503 #endif //DEBUG
 504
 505                 /* Have we received a signal ? */
 506                 if(quit_program) break;
 507
 508                 num_rdy = poll(pollfd, fd_pairs->num_pairs, -1);
 509                 if(num_rdy == -1) {
 510                         perror("Poll error");
 511                         goto free_fd;
 512                 }
 513
 514                 printf("Data received\n");
 515
 516                 for(i=0;i<fd_pairs->num_pairs;i++) {
 517                         switch(pollfd[i].revents) {
 518                                 case POLLERR:
 519                                         printf("Error returned in polling fd %d.\n", pollfd[i].fd);
 520                                         num_hup++;
 521                                         break;
 522                                 case POLLHUP:
 523                                         printf("Polling fd %d tells it has hung up.\n", pollfd[i].fd);
 524                                         num_hup++;
 525                                         break;
 526                                 case POLLNVAL:
 527                                         printf("Polling fd %d tells fd is not open.\n", pollfd[i].fd);
 528                                         num_hup++;
 529                                         break;
 530                                 case POLLPRI:
 531                                         if(pthread_mutex_trylock(&fd_pairs->pair[i].mutex) == 0) {
 532                                                 printf("Urgent read on fd %d\n", pollfd[i].fd);
 533                                                 /* Take care of high priority channels first. */
 534                                                 high_prio = 1;
 535                                                 /* it's ok to have an unavailable subbuffer */
 536                                                 ret = read_subbuffer(&fd_pairs->pair[i]);
 537                                                 if(ret == -EAGAIN) ret = 0;
 538
 539                                                 ret = pthread_mutex_unlock(&fd_pairs->pair[i].mutex);
 540                                                 if(ret)
 541                                                         printf("Error in mutex unlock : %s\n", strerror(ret));
 542                                         }
 543                                         break;
 544                         }
 545                 }
 546                 /* If every FD has hung up, we end the read loop here */
 547                 if(num_hup == fd_pairs->num_pairs) break;
 548
 549                 if(!high_prio) {
 550                         for(i=0;i<fd_pairs->num_pairs;i++) {
 551                                 switch(pollfd[i].revents) {
 552                                         case POLLIN:
 553                                                 if(pthread_mutex_trylock(&fd_pairs->pair[i].mutex) == 0) {
 554                                                         /* Take care of low priority channels. */
 555                                                         printf("Normal read on fd %d\n", pollfd[i].fd);
 556                                                         /* it's ok to have an unavailable subbuffer */
 557                                                         ret = read_subbuffer(&fd_pairs->pair[i]);
 558                                                         if(ret == -EAGAIN) ret = 0;
 559
 560                                                         ret = pthread_mutex_unlock(&fd_pairs->pair[i].mutex);
 561                                                         if(ret)
 562                                                                 printf("Error in mutex unlock : %s\n", strerror(ret));
 563                                                 }
 564                                                 break;
 565                                 }
 566                         }
 567                 }
 568
 569         }
 570
 571 free_fd:
 572         free(pollfd);
 573
 574 end:
 575         return (void*)ret;
 576 }
 577
 578
 579 void close_channel_trace_pairs(struct channel_trace_fd *fd_pairs)
 580 {
 581         int i;
 582         int ret;
 583
 584         for(i=0;i<fd_pairs->num_pairs;i++) {
 585                 ret = close(fd_pairs->pair[i].channel);
 586                 if(ret == -1) perror("Close error on channel");
 587                 ret = close(fd_pairs->pair[i].trace);
 588                 if(ret == -1) perror("Close error on trace");
 589         }
 590         free(fd_pairs->pair);
 591 }
 592
 593 int main(int argc, char ** argv)
 594 {
 595         int ret = 0;
 596         struct channel_trace_fd fd_pairs = { NULL, 0 };
 597         struct sigaction act;
 598         pthread_t *tids;
 599         unsigned int i;
 600         void *tret;
 601
 602         ret = parse_arguments(argc, argv);
 603
 604         if(ret != 0) show_arguments();
 605         if(ret < 0) return EINVAL;
 606         if(ret > 0) return 0;
 607
 608         show_info();
 609
 610         if(daemon_mode) {
 611                 ret = daemon(0, 0);
 612
 613     if(ret == -1) {
 614       perror("An error occured while daemonizing.");
 615       exit(-1);
 616     }
 617   }
 618
 619         /* Connect the signal handlers */
 620         act.sa_handler = handler;
 621         act.sa_flags = 0;
 622         sigemptyset(&(act.sa_mask));
 623         sigaddset(&(act.sa_mask), SIGTERM);
 624         sigaddset(&(act.sa_mask), SIGQUIT);
 625         sigaddset(&(act.sa_mask), SIGINT);
 626         sigaction(SIGTERM, &act, NULL);
 627         sigaction(SIGQUIT, &act, NULL);
 628         sigaction(SIGINT, &act, NULL);
 629
 630
 631         if(ret = open_channel_trace_pairs(channel_name, trace_name, &fd_pairs))
 632                 goto close_channel;
 633
 634         if(ret = map_channels(&fd_pairs))
 635                 goto close_channel;
 636
 637         tids = malloc(sizeof(pthread_t) * num_threads);
 638         for(i=0; i<num_threads; i++) {
 639                 ret = pthread_create(&tids[i], NULL, read_channels, &fd_pairs);
 640                 if(ret) {
 641                         perror("Error creating thread");
 642                         break;
 643                 }
 644         }
 645
 646         for(i=0; i<num_threads; i++) {
 647                 ret = pthread_join(tids[i], &tret);
 648                 if(ret) {
 649                         perror("Error joining thread");
 650                         break;
 651                 }
 652                 if((int)tret != 0) {
 653                         printf("Error %s occured in thread %u\n", strerror((int)tret), i);
 654                 }
 655         }
 656
 657         free(tids);
 658
 659         ret |= unmap_channels(&fd_pairs);
 660
 661 close_channel:
 662         close_channel_trace_pairs(&fd_pairs);
 663
 664         return ret;
 665 }