libcounter/shm.c

   1 /*
   2  * SPDX-License-Identifier: LGPL-2.1-only
   3  *
   4  * Copyright (C) 2005-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   5  */
   6
   7 #define _LGPL_SOURCE
   8 #include "shm.h"
   9 #include <unistd.h>
  10 #include <fcntl.h>
  11 #include <sys/mman.h>
  12 #include <sys/types.h>
  13 #include <sys/stat.h>   /* For mode constants */
  14 #include <fcntl.h>      /* For O_* constants */
  15 #include <assert.h>
  16 #include <stdio.h>
  17 #include <signal.h>
  18 #include <dirent.h>
  19 #include <limits.h>
  20 #include <stdbool.h>
  21 #include <stdint.h>
  22
  23 #ifdef HAVE_LIBNUMA
  24 #include <numa.h>
  25 #include <numaif.h>
  26 #endif
  27
  28 #include <lttng/ust-utils.h>
  29
  30 #include <ust-helper.h>
  31 #include <ust-fd.h>
  32 #include "../libringbuffer/mmap.h"
  33
  34 /*
  35  * Ensure we have the required amount of space available by writing 0
  36  * into the entire buffer. Not doing so can trigger SIGBUS when going
  37  * beyond the available shm space.
  38  */
  39 static
  40 int zero_file(int fd, size_t len)
  41 {
  42         ssize_t retlen;
  43         size_t written = 0;
  44         char *zeropage;
  45         long pagelen;
  46         int ret;
  47
  48         pagelen = sysconf(_SC_PAGESIZE);
  49         if (pagelen < 0)
  50                 return (int) pagelen;
  51         zeropage = calloc(pagelen, 1);
  52         if (!zeropage)
  53                 return -ENOMEM;
  54
  55         while (len > written) {
  56                 do {
  57                         retlen = write(fd, zeropage,
  58                                 min_t(size_t, pagelen, len - written));
  59                 } while (retlen == -1UL && errno == EINTR);
  60                 if (retlen < 0) {
  61                         ret = (int) retlen;
  62                         goto error;
  63                 }
  64                 written += retlen;
  65         }
  66         ret = 0;
  67 error:
  68         free(zeropage);
  69         return ret;
  70 }
  71
  72 struct lttng_counter_shm_object_table *lttng_counter_shm_object_table_create(size_t max_nb_obj)
  73 {
  74         struct lttng_counter_shm_object_table *table;
  75
  76         table = zmalloc(sizeof(struct lttng_counter_shm_object_table) +
  77                         max_nb_obj * sizeof(table->objects[0]));
  78         if (!table)
  79                 return NULL;
  80         table->size = max_nb_obj;
  81         return table;
  82 }
  83
  84 static
  85 struct lttng_counter_shm_object *_lttng_counter_shm_object_table_alloc_shm(struct lttng_counter_shm_object_table *table,
  86                                            size_t memory_map_size,
  87                                            int cpu_fd)
  88 {
  89         int shmfd, ret;
  90         struct lttng_counter_shm_object *obj;
  91         char *memory_map;
  92
  93         if (cpu_fd < 0)
  94                 return NULL;
  95         if (table->allocated_len >= table->size)
  96                 return NULL;
  97         obj = &table->objects[table->allocated_len];
  98
  99         /* create shm */
 100
 101         shmfd = cpu_fd;
 102         ret = zero_file(shmfd, memory_map_size);
 103         if (ret) {
 104                 PERROR("zero_file");
 105                 goto error_zero_file;
 106         }
 107         ret = ftruncate(shmfd, memory_map_size);
 108         if (ret) {
 109                 PERROR("ftruncate");
 110                 goto error_ftruncate;
 111         }
 112         /*
 113          * Also ensure the file metadata is synced with the storage by using
 114          * fsync(2).
 115          */
 116         ret = fsync(shmfd);
 117         if (ret) {
 118                 PERROR("fsync");
 119                 goto error_fsync;
 120         }
 121         obj->shm_fd_ownership = 0;
 122         obj->shm_fd = shmfd;
 123
 124         /* memory_map: mmap */
 125         memory_map = mmap(NULL, memory_map_size, PROT_READ | PROT_WRITE,
 126                           MAP_SHARED | LTTNG_MAP_POPULATE, shmfd, 0);
 127         if (memory_map == MAP_FAILED) {
 128                 PERROR("mmap");
 129                 goto error_mmap;
 130         }
 131         obj->type = LTTNG_COUNTER_SHM_OBJECT_SHM;
 132         obj->memory_map = memory_map;
 133         obj->memory_map_size = memory_map_size;
 134         obj->allocated_len = 0;
 135         obj->index = table->allocated_len++;
 136
 137         return obj;
 138
 139 error_mmap:
 140 error_fsync:
 141 error_ftruncate:
 142 error_zero_file:
 143         return NULL;
 144 }
 145
 146 static
 147 struct lttng_counter_shm_object *_lttng_counter_shm_object_table_alloc_mem(struct lttng_counter_shm_object_table *table,
 148                                            size_t memory_map_size)
 149 {
 150         struct lttng_counter_shm_object *obj;
 151         void *memory_map;
 152
 153         if (table->allocated_len >= table->size)
 154                 return NULL;
 155         obj = &table->objects[table->allocated_len];
 156
 157         memory_map = zmalloc(memory_map_size);
 158         if (!memory_map)
 159                 goto alloc_error;
 160
 161         /* no shm_fd */
 162         obj->shm_fd = -1;
 163         obj->shm_fd_ownership = 0;
 164
 165         obj->type = LTTNG_COUNTER_SHM_OBJECT_MEM;
 166         obj->memory_map = memory_map;
 167         obj->memory_map_size = memory_map_size;
 168         obj->allocated_len = 0;
 169         obj->index = table->allocated_len++;
 170
 171         return obj;
 172
 173 alloc_error:
 174         return NULL;
 175 }
 176
 177 /*
 178  * libnuma prints errors on the console even for numa_available().
 179  * Work-around this limitation by using get_mempolicy() directly to
 180  * check whether the kernel supports mempolicy.
 181  */
 182 #ifdef HAVE_LIBNUMA
 183 static bool lttng_is_numa_available(void)
 184 {
 185         int ret;
 186
 187         ret = get_mempolicy(NULL, NULL, 0, NULL, 0);
 188         if (ret && errno == ENOSYS) {
 189                 return false;
 190         }
 191         return numa_available() > 0;
 192 }
 193 #endif
 194
 195 struct lttng_counter_shm_object *lttng_counter_shm_object_table_alloc(struct lttng_counter_shm_object_table *table,
 196                         size_t memory_map_size,
 197                         enum lttng_counter_shm_object_type type,
 198                         int cpu_fd,
 199                         int cpu)
 200 {
 201         struct lttng_counter_shm_object *shm_object;
 202 #ifdef HAVE_LIBNUMA
 203         int oldnode = 0, node;
 204         bool numa_avail;
 205
 206         numa_avail = lttng_is_numa_available();
 207         if (numa_avail) {
 208                 oldnode = numa_preferred();
 209                 if (cpu >= 0) {
 210                         node = numa_node_of_cpu(cpu);
 211                         if (node >= 0)
 212                                 numa_set_preferred(node);
 213                 }
 214                 if (cpu < 0 || node < 0)
 215                         numa_set_localalloc();
 216         }
 217 #endif /* HAVE_LIBNUMA */
 218         switch (type) {
 219         case LTTNG_COUNTER_SHM_OBJECT_SHM:
 220                 shm_object = _lttng_counter_shm_object_table_alloc_shm(table, memory_map_size,
 221                                 cpu_fd);
 222                 break;
 223         case LTTNG_COUNTER_SHM_OBJECT_MEM:
 224                 shm_object = _lttng_counter_shm_object_table_alloc_mem(table, memory_map_size);
 225                 break;
 226         default:
 227                 assert(0);
 228         }
 229 #ifdef HAVE_LIBNUMA
 230         if (numa_avail)
 231                 numa_set_preferred(oldnode);
 232 #endif /* HAVE_LIBNUMA */
 233         return shm_object;
 234 }
 235
 236 struct lttng_counter_shm_object *lttng_counter_shm_object_table_append_shm(struct lttng_counter_shm_object_table *table,
 237                         int shm_fd,
 238                         size_t memory_map_size)
 239 {
 240         struct lttng_counter_shm_object *obj;
 241         char *memory_map;
 242
 243         if (table->allocated_len >= table->size)
 244                 return NULL;
 245
 246         obj = &table->objects[table->allocated_len];
 247
 248         obj->shm_fd = shm_fd;
 249         obj->shm_fd_ownership = 1;
 250
 251         /* memory_map: mmap */
 252         memory_map = mmap(NULL, memory_map_size, PROT_READ | PROT_WRITE,
 253                           MAP_SHARED | LTTNG_MAP_POPULATE, shm_fd, 0);
 254         if (memory_map == MAP_FAILED) {
 255                 PERROR("mmap");
 256                 goto error_mmap;
 257         }
 258         obj->type = LTTNG_COUNTER_SHM_OBJECT_SHM;
 259         obj->memory_map = memory_map;
 260         obj->memory_map_size = memory_map_size;
 261         obj->allocated_len = memory_map_size;
 262         obj->index = table->allocated_len++;
 263
 264         return obj;
 265
 266 error_mmap:
 267         return NULL;
 268 }
 269
 270 /*
 271  * Passing ownership of mem to object.
 272  */
 273 struct lttng_counter_shm_object *lttng_counter_shm_object_table_append_mem(struct lttng_counter_shm_object_table *table,
 274                         void *mem, size_t memory_map_size)
 275 {
 276         struct lttng_counter_shm_object *obj;
 277
 278         if (table->allocated_len >= table->size)
 279                 return NULL;
 280         obj = &table->objects[table->allocated_len];
 281
 282         obj->shm_fd = -1;
 283         obj->shm_fd_ownership = 0;
 284
 285         obj->type = LTTNG_COUNTER_SHM_OBJECT_MEM;
 286         obj->memory_map = mem;
 287         obj->memory_map_size = memory_map_size;
 288         obj->allocated_len = memory_map_size;
 289         obj->index = table->allocated_len++;
 290
 291         return obj;
 292
 293         return NULL;
 294 }
 295
 296 static
 297 void lttng_counter_shmp_object_destroy(struct lttng_counter_shm_object *obj, int consumer)
 298 {
 299         switch (obj->type) {
 300         case LTTNG_COUNTER_SHM_OBJECT_SHM:
 301         {
 302                 int ret;
 303
 304                 ret = munmap(obj->memory_map, obj->memory_map_size);
 305                 if (ret) {
 306                         PERROR("umnmap");
 307                         assert(0);
 308                 }
 309
 310                 if (obj->shm_fd_ownership) {
 311                         /* Delete FDs only if called from app (not consumer). */
 312                         if (!consumer) {
 313                                 lttng_ust_lock_fd_tracker();
 314                                 ret = close(obj->shm_fd);
 315                                 if (!ret) {
 316                                         lttng_ust_delete_fd_from_tracker(obj->shm_fd);
 317                                 } else {
 318                                         PERROR("close");
 319                                         assert(0);
 320                                 }
 321                                 lttng_ust_unlock_fd_tracker();
 322                         } else {
 323                                 ret = close(obj->shm_fd);
 324                                 if (ret) {
 325                                         PERROR("close");
 326                                         assert(0);
 327                                 }
 328                         }
 329                 }
 330                 break;
 331         }
 332         case LTTNG_COUNTER_SHM_OBJECT_MEM:
 333         {
 334                 free(obj->memory_map);
 335                 break;
 336         }
 337         default:
 338                 assert(0);
 339         }
 340 }
 341
 342 void lttng_counter_shm_object_table_destroy(struct lttng_counter_shm_object_table *table, int consumer)
 343 {
 344         int i;
 345
 346         for (i = 0; i < table->allocated_len; i++)
 347                 lttng_counter_shmp_object_destroy(&table->objects[i], consumer);
 348         free(table);
 349 }
 350
 351 /*
 352  * lttng_counter_zalloc_shm - allocate memory within a shm object.
 353  *
 354  * Shared memory is already zeroed by shmget.
 355  * *NOT* multithread-safe (should be protected by mutex).
 356  * Returns a -1, -1 tuple on error.
 357  */
 358 struct lttng_counter_shm_ref lttng_counter_zalloc_shm(struct lttng_counter_shm_object *obj, size_t len)
 359 {
 360         struct lttng_counter_shm_ref ref;
 361         struct lttng_counter_shm_ref shm_ref_error = { -1, -1 };
 362
 363         if (obj->memory_map_size - obj->allocated_len < len)
 364                 return shm_ref_error;
 365         ref.index = obj->index;
 366         ref.offset =  obj->allocated_len;
 367         obj->allocated_len += len;
 368         return ref;
 369 }
 370
 371 void lttng_counter_align_shm(struct lttng_counter_shm_object *obj, size_t align)
 372 {
 373         size_t offset_len = lttng_ust_offset_align(obj->allocated_len, align);
 374         obj->allocated_len += offset_len;
 375 }