libringbuffer/shm.c

   1 /*
   2  * libringbuffer/shm.c
   3  *
   4  * Copyright (C) 2005-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   5  *
   6  * This library is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU Lesser General Public
   8  * License as published by the Free Software Foundation; only
   9  * version 2.1 of the License.
  10  *
  11  * This library is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  14  * Lesser General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU Lesser General Public
  17  * License along with this library; if not, write to the Free Software
  18  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  19  */
  20
  21 #define _LGPL_SOURCE
  22 #include <config.h>
  23 #include "shm.h"
  24 #include <unistd.h>
  25 #include <fcntl.h>
  26 #include <sys/mman.h>
  27 #include <sys/types.h>
  28 #include <sys/stat.h>   /* For mode constants */
  29 #include <fcntl.h>      /* For O_* constants */
  30 #include <assert.h>
  31 #include <stdio.h>
  32 #include <signal.h>
  33 #include <dirent.h>
  34 #include <lttng/align.h>
  35 #include <limits.h>
  36 #include <stdbool.h>
  37 #ifdef HAVE_LIBNUMA
  38 #include <numa.h>
  39 #include <numaif.h>
  40 #endif
  41 #include <helper.h>
  42 #include <ust-fd.h>
  43 #include "mmap.h"
  44
  45 /*
  46  * Ensure we have the required amount of space available by writing 0
  47  * into the entire buffer. Not doing so can trigger SIGBUS when going
  48  * beyond the available shm space.
  49  */
  50 static
  51 int zero_file(int fd, size_t len)
  52 {
  53         ssize_t retlen;
  54         size_t written = 0;
  55         char *zeropage;
  56         long pagelen;
  57         int ret;
  58
  59         pagelen = sysconf(_SC_PAGESIZE);
  60         if (pagelen < 0)
  61                 return (int) pagelen;
  62         zeropage = calloc(pagelen, 1);
  63         if (!zeropage)
  64                 return -ENOMEM;
  65
  66         while (len > written) {
  67                 do {
  68                         retlen = write(fd, zeropage,
  69                                 min_t(size_t, pagelen, len - written));
  70                 } while (retlen == -1UL && errno == EINTR);
  71                 if (retlen < 0) {
  72                         ret = (int) retlen;
  73                         goto error;
  74                 }
  75                 written += retlen;
  76         }
  77         ret = 0;
  78 error:
  79         free(zeropage);
  80         return ret;
  81 }
  82
  83 struct shm_object_table *shm_object_table_create(size_t max_nb_obj)
  84 {
  85         struct shm_object_table *table;
  86
  87         table = zmalloc(sizeof(struct shm_object_table) +
  88                         max_nb_obj * sizeof(table->objects[0]));
  89         if (!table)
  90                 return NULL;
  91         table->size = max_nb_obj;
  92         return table;
  93 }
  94
  95 static
  96 struct shm_object *_shm_object_table_alloc_shm(struct shm_object_table *table,
  97                                            size_t memory_map_size,
  98                                            int stream_fd)
  99 {
 100         int shmfd, waitfd[2], ret, i;
 101         struct shm_object *obj;
 102         char *memory_map;
 103
 104         if (stream_fd < 0)
 105                 return NULL;
 106         if (table->allocated_len >= table->size)
 107                 return NULL;
 108         obj = &table->objects[table->allocated_len];
 109
 110         /* wait_fd: create pipe */
 111         ret = pipe(waitfd);
 112         if (ret < 0) {
 113                 PERROR("pipe");
 114                 goto error_pipe;
 115         }
 116         for (i = 0; i < 2; i++) {
 117                 ret = fcntl(waitfd[i], F_SETFD, FD_CLOEXEC);
 118                 if (ret < 0) {
 119                         PERROR("fcntl");
 120                         goto error_fcntl;
 121                 }
 122         }
 123         /* The write end of the pipe needs to be non-blocking */
 124         ret = fcntl(waitfd[1], F_SETFL, O_NONBLOCK);
 125         if (ret < 0) {
 126                 PERROR("fcntl");
 127                 goto error_fcntl;
 128         }
 129         memcpy(obj->wait_fd, waitfd, sizeof(waitfd));
 130
 131         /* create shm */
 132
 133         shmfd = stream_fd;
 134         ret = zero_file(shmfd, memory_map_size);
 135         if (ret) {
 136                 PERROR("zero_file");
 137                 goto error_zero_file;
 138         }
 139         ret = ftruncate(shmfd, memory_map_size);
 140         if (ret) {
 141                 PERROR("ftruncate");
 142                 goto error_ftruncate;
 143         }
 144         /*
 145          * Also ensure the file metadata is synced with the storage by using
 146          * fsync(2).
 147          */
 148         ret = fsync(shmfd);
 149         if (ret) {
 150                 PERROR("fsync");
 151                 goto error_fsync;
 152         }
 153         obj->shm_fd_ownership = 0;
 154         obj->shm_fd = shmfd;
 155
 156         /* memory_map: mmap */
 157         memory_map = mmap(NULL, memory_map_size, PROT_READ | PROT_WRITE,
 158                           MAP_SHARED | LTTNG_MAP_POPULATE, shmfd, 0);
 159         if (memory_map == MAP_FAILED) {
 160                 PERROR("mmap");
 161                 goto error_mmap;
 162         }
 163         obj->type = SHM_OBJECT_SHM;
 164         obj->memory_map = memory_map;
 165         obj->memory_map_size = memory_map_size;
 166         obj->allocated_len = 0;
 167         obj->index = table->allocated_len++;
 168
 169         return obj;
 170
 171 error_mmap:
 172 error_fsync:
 173 error_ftruncate:
 174 error_zero_file:
 175 error_fcntl:
 176         for (i = 0; i < 2; i++) {
 177                 ret = close(waitfd[i]);
 178                 if (ret) {
 179                         PERROR("close");
 180                         assert(0);
 181                 }
 182         }
 183 error_pipe:
 184         return NULL;
 185 }
 186
 187 static
 188 struct shm_object *_shm_object_table_alloc_mem(struct shm_object_table *table,
 189                                            size_t memory_map_size)
 190 {
 191         struct shm_object *obj;
 192         void *memory_map;
 193         int waitfd[2], i, ret;
 194
 195         if (table->allocated_len >= table->size)
 196                 return NULL;
 197         obj = &table->objects[table->allocated_len];
 198
 199         memory_map = zmalloc(memory_map_size);
 200         if (!memory_map)
 201                 goto alloc_error;
 202
 203         /* wait_fd: create pipe */
 204         ret = pipe(waitfd);
 205         if (ret < 0) {
 206                 PERROR("pipe");
 207                 goto error_pipe;
 208         }
 209         for (i = 0; i < 2; i++) {
 210                 ret = fcntl(waitfd[i], F_SETFD, FD_CLOEXEC);
 211                 if (ret < 0) {
 212                         PERROR("fcntl");
 213                         goto error_fcntl;
 214                 }
 215         }
 216         /* The write end of the pipe needs to be non-blocking */
 217         ret = fcntl(waitfd[1], F_SETFL, O_NONBLOCK);
 218         if (ret < 0) {
 219                 PERROR("fcntl");
 220                 goto error_fcntl;
 221         }
 222         memcpy(obj->wait_fd, waitfd, sizeof(waitfd));
 223
 224         /* no shm_fd */
 225         obj->shm_fd = -1;
 226         obj->shm_fd_ownership = 0;
 227
 228         obj->type = SHM_OBJECT_MEM;
 229         obj->memory_map = memory_map;
 230         obj->memory_map_size = memory_map_size;
 231         obj->allocated_len = 0;
 232         obj->index = table->allocated_len++;
 233
 234         return obj;
 235
 236 error_fcntl:
 237         for (i = 0; i < 2; i++) {
 238                 ret = close(waitfd[i]);
 239                 if (ret) {
 240                         PERROR("close");
 241                         assert(0);
 242                 }
 243         }
 244 error_pipe:
 245         free(memory_map);
 246 alloc_error:
 247         return NULL;
 248 }
 249
 250 /*
 251  * libnuma prints errors on the console even for numa_available().
 252  * Work-around this limitation by using get_mempolicy() directly to
 253  * check whether the kernel supports mempolicy.
 254  */
 255 #ifdef HAVE_LIBNUMA
 256 static bool lttng_is_numa_available(void)
 257 {
 258         int ret;
 259
 260         ret = get_mempolicy(NULL, NULL, 0, NULL, 0);
 261         if (ret && errno == ENOSYS) {
 262                 return false;
 263         }
 264         return numa_available() > 0;
 265 }
 266 #endif
 267
 268 struct shm_object *shm_object_table_alloc(struct shm_object_table *table,
 269                         size_t memory_map_size,
 270                         enum shm_object_type type,
 271                         int stream_fd,
 272                         int cpu)
 273 {
 274         struct shm_object *shm_object;
 275 #ifdef HAVE_LIBNUMA
 276         int oldnode = 0, node;
 277         bool numa_avail;
 278
 279         numa_avail = lttng_is_numa_available();
 280         if (numa_avail) {
 281                 oldnode = numa_preferred();
 282                 if (cpu >= 0) {
 283                         node = numa_node_of_cpu(cpu);
 284                         if (node >= 0)
 285                                 numa_set_preferred(node);
 286                 }
 287                 if (cpu < 0 || node < 0)
 288                         numa_set_localalloc();
 289         }
 290 #endif /* HAVE_LIBNUMA */
 291         switch (type) {
 292         case SHM_OBJECT_SHM:
 293                 shm_object = _shm_object_table_alloc_shm(table, memory_map_size,
 294                                 stream_fd);
 295                 break;
 296         case SHM_OBJECT_MEM:
 297                 shm_object = _shm_object_table_alloc_mem(table, memory_map_size);
 298                 break;
 299         default:
 300                 assert(0);
 301         }
 302 #ifdef HAVE_LIBNUMA
 303         if (numa_avail)
 304                 numa_set_preferred(oldnode);
 305 #endif /* HAVE_LIBNUMA */
 306         return shm_object;
 307 }
 308
 309 struct shm_object *shm_object_table_append_shm(struct shm_object_table *table,
 310                         int shm_fd, int wakeup_fd, uint32_t stream_nr,
 311                         size_t memory_map_size)
 312 {
 313         struct shm_object *obj;
 314         char *memory_map;
 315         int ret;
 316
 317         if (table->allocated_len >= table->size)
 318                 return NULL;
 319         /* streams _must_ be received in sequential order, else fail. */
 320         if (stream_nr + 1 != table->allocated_len)
 321                 return NULL;
 322
 323         obj = &table->objects[table->allocated_len];
 324
 325         /* wait_fd: set write end of the pipe. */
 326         obj->wait_fd[0] = -1;   /* read end is unset */
 327         obj->wait_fd[1] = wakeup_fd;
 328         obj->shm_fd = shm_fd;
 329         obj->shm_fd_ownership = 1;
 330
 331         /* The write end of the pipe needs to be non-blocking */
 332         ret = fcntl(obj->wait_fd[1], F_SETFL, O_NONBLOCK);
 333         if (ret < 0) {
 334                 PERROR("fcntl");
 335                 goto error_fcntl;
 336         }
 337
 338         /* memory_map: mmap */
 339         memory_map = mmap(NULL, memory_map_size, PROT_READ | PROT_WRITE,
 340                           MAP_SHARED | LTTNG_MAP_POPULATE, shm_fd, 0);
 341         if (memory_map == MAP_FAILED) {
 342                 PERROR("mmap");
 343                 goto error_mmap;
 344         }
 345         obj->type = SHM_OBJECT_SHM;
 346         obj->memory_map = memory_map;
 347         obj->memory_map_size = memory_map_size;
 348         obj->allocated_len = memory_map_size;
 349         obj->index = table->allocated_len++;
 350
 351         return obj;
 352
 353 error_fcntl:
 354 error_mmap:
 355         return NULL;
 356 }
 357
 358 /*
 359  * Passing ownership of mem to object.
 360  */
 361 struct shm_object *shm_object_table_append_mem(struct shm_object_table *table,
 362                         void *mem, size_t memory_map_size, int wakeup_fd)
 363 {
 364         struct shm_object *obj;
 365         int ret;
 366
 367         if (table->allocated_len >= table->size)
 368                 return NULL;
 369         obj = &table->objects[table->allocated_len];
 370
 371         obj->wait_fd[0] = -1;   /* read end is unset */
 372         obj->wait_fd[1] = wakeup_fd;
 373         obj->shm_fd = -1;
 374         obj->shm_fd_ownership = 0;
 375
 376         ret = fcntl(obj->wait_fd[1], F_SETFD, FD_CLOEXEC);
 377         if (ret < 0) {
 378                 PERROR("fcntl");
 379                 goto error_fcntl;
 380         }
 381         /* The write end of the pipe needs to be non-blocking */
 382         ret = fcntl(obj->wait_fd[1], F_SETFL, O_NONBLOCK);
 383         if (ret < 0) {
 384                 PERROR("fcntl");
 385                 goto error_fcntl;
 386         }
 387
 388         obj->type = SHM_OBJECT_MEM;
 389         obj->memory_map = mem;
 390         obj->memory_map_size = memory_map_size;
 391         obj->allocated_len = memory_map_size;
 392         obj->index = table->allocated_len++;
 393
 394         return obj;
 395
 396 error_fcntl:
 397         return NULL;
 398 }
 399
 400 static
 401 void shmp_object_destroy(struct shm_object *obj, int consumer)
 402 {
 403         switch (obj->type) {
 404         case SHM_OBJECT_SHM:
 405         {
 406                 int ret, i;
 407
 408                 ret = munmap(obj->memory_map, obj->memory_map_size);
 409                 if (ret) {
 410                         PERROR("umnmap");
 411                         assert(0);
 412                 }
 413
 414                 if (obj->shm_fd_ownership) {
 415                         /* Delete FDs only if called from app (not consumer). */
 416                         if (!consumer) {
 417                                 lttng_ust_lock_fd_tracker();
 418                                 ret = close(obj->shm_fd);
 419                                 if (!ret) {
 420                                         lttng_ust_delete_fd_from_tracker(obj->shm_fd);
 421                                 } else {
 422                                         PERROR("close");
 423                                         assert(0);
 424                                 }
 425                                 lttng_ust_unlock_fd_tracker();
 426                         } else {
 427                                 ret = close(obj->shm_fd);
 428                                 if (ret) {
 429                                         PERROR("close");
 430                                         assert(0);
 431                                 }
 432                         }
 433                 }
 434                 for (i = 0; i < 2; i++) {
 435                         if (obj->wait_fd[i] < 0)
 436                                 continue;
 437                         if (!consumer) {
 438                                 lttng_ust_lock_fd_tracker();
 439                                 ret = close(obj->wait_fd[i]);
 440                                 if (!ret) {
 441                                         lttng_ust_delete_fd_from_tracker(obj->wait_fd[i]);
 442                                 } else {
 443                                         PERROR("close");
 444                                         assert(0);
 445                                 }
 446                                 lttng_ust_unlock_fd_tracker();
 447                         } else {
 448                                 ret = close(obj->wait_fd[i]);
 449                                 if (ret) {
 450                                         PERROR("close");
 451                                         assert(0);
 452                                 }
 453                         }
 454                 }
 455                 break;
 456         }
 457         case SHM_OBJECT_MEM:
 458         {
 459                 int ret, i;
 460
 461                 for (i = 0; i < 2; i++) {
 462                         if (obj->wait_fd[i] < 0)
 463                                 continue;
 464                         if (!consumer) {
 465                                 lttng_ust_lock_fd_tracker();
 466                                 ret = close(obj->wait_fd[i]);
 467                                 if (!ret) {
 468                                         lttng_ust_delete_fd_from_tracker(obj->wait_fd[i]);
 469                                 } else {
 470                                         PERROR("close");
 471                                         assert(0);
 472                                 }
 473                                 lttng_ust_unlock_fd_tracker();
 474                         } else {
 475                                 ret = close(obj->wait_fd[i]);
 476                                 if (ret) {
 477                                         PERROR("close");
 478                                         assert(0);
 479                                 }
 480                         }
 481                 }
 482                 free(obj->memory_map);
 483                 break;
 484         }
 485         default:
 486                 assert(0);
 487         }
 488 }
 489
 490 void shm_object_table_destroy(struct shm_object_table *table, int consumer)
 491 {
 492         int i;
 493
 494         for (i = 0; i < table->allocated_len; i++)
 495                 shmp_object_destroy(&table->objects[i], consumer);
 496         free(table);
 497 }
 498
 499 /*
 500  * zalloc_shm - allocate memory within a shm object.
 501  *
 502  * Shared memory is already zeroed by shmget.
 503  * *NOT* multithread-safe (should be protected by mutex).
 504  * Returns a -1, -1 tuple on error.
 505  */
 506 struct shm_ref zalloc_shm(struct shm_object *obj, size_t len)
 507 {
 508         struct shm_ref ref;
 509         struct shm_ref shm_ref_error = { -1, -1 };
 510
 511         if (obj->memory_map_size - obj->allocated_len < len)
 512                 return shm_ref_error;
 513         ref.index = obj->index;
 514         ref.offset =  obj->allocated_len;
 515         obj->allocated_len += len;
 516         return ref;
 517 }
 518
 519 void align_shm(struct shm_object *obj, size_t align)
 520 {
 521         size_t offset_len = offset_align(obj->allocated_len, align);
 522         obj->allocated_len += offset_len;
 523 }