src/cgroup.c

   1 /*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
   2
   3 /***
   4   This file is part of systemd.
   5
   6   Copyright 2010 Lennart Poettering
   7
   8   systemd is free software; you can redistribute it and/or modify it
   9   under the terms of the GNU General Public License as published by
  10   the Free Software Foundation; either version 2 of the License, or
  11   (at your option) any later version.
  12
  13   systemd is distributed in the hope that it will be useful, but
  14   WITHOUT ANY WARRANTY; without even the implied warranty of
  15   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  16   General Public License for more details.
  17
  18   You should have received a copy of the GNU General Public License
  19   along with systemd; If not, see <http://www.gnu.org/licenses/>.
  20 ***/
  21
  22 #include <errno.h>
  23 #include <assert.h>
  24 #include <unistd.h>
  25 #include <sys/types.h>
  26 #include <signal.h>
  27 #include <sys/mount.h>
  28 #include <fcntl.h>
  29
  30 #include "cgroup.h"
  31 #include "cgroup-util.h"
  32 #include "log.h"
  33
  34 int cgroup_bonding_realize(CGroupBonding *b) {
  35         int r;
  36
  37         assert(b);
  38         assert(b->path);
  39         assert(b->controller);
  40
  41         if (b->realized)
  42                 return 0;
  43
  44         r = cg_create(b->controller, b->path);
  45         if (r < 0) {
  46                 log_warning("Failed to create cgroup %s:%s: %s", b->controller, b->path, strerror(-r));
  47                 return r;
  48         }
  49
  50         b->realized = true;
  51
  52         return 0;
  53 }
  54
  55 int cgroup_bonding_realize_list(CGroupBonding *first) {
  56         CGroupBonding *b;
  57         int r;
  58
  59         LIST_FOREACH(by_unit, b, first)
  60                 if ((r = cgroup_bonding_realize(b)) < 0 && b->essential)
  61                         return r;
  62
  63         return 0;
  64 }
  65
  66 void cgroup_bonding_free(CGroupBonding *b, bool remove_or_trim) {
  67         assert(b);
  68
  69         if (b->unit) {
  70                 CGroupBonding *f;
  71
  72                 LIST_REMOVE(CGroupBonding, by_unit, b->unit->meta.cgroup_bondings, b);
  73
  74                 if (streq(b->controller, SYSTEMD_CGROUP_CONTROLLER)) {
  75                         assert_se(f = hashmap_get(b->unit->meta.manager->cgroup_bondings, b->path));
  76                         LIST_REMOVE(CGroupBonding, by_path, f, b);
  77
  78                         if (f)
  79                                 hashmap_replace(b->unit->meta.manager->cgroup_bondings, b->path, f);
  80                         else
  81                                 hashmap_remove(b->unit->meta.manager->cgroup_bondings, b->path);
  82                 }
  83         }
  84
  85         if (b->realized && b->ours && remove_or_trim) {
  86
  87                 if (cgroup_bonding_is_empty(b) > 0)
  88                         cg_delete(b->controller, b->path);
  89                 else
  90                         cg_trim(b->controller, b->path, false);
  91         }
  92
  93         free(b->controller);
  94         free(b->path);
  95         free(b);
  96 }
  97
  98 void cgroup_bonding_free_list(CGroupBonding *first, bool remove_or_trim) {
  99         CGroupBonding *b, *n;
 100
 101         LIST_FOREACH_SAFE(by_unit, b, n, first)
 102                 cgroup_bonding_free(b, remove_or_trim);
 103 }
 104
 105 void cgroup_bonding_trim(CGroupBonding *b, bool delete_root) {
 106         assert(b);
 107
 108         if (b->realized && b->ours)
 109                 cg_trim(b->controller, b->path, delete_root);
 110 }
 111
 112 void cgroup_bonding_trim_list(CGroupBonding *first, bool delete_root) {
 113         CGroupBonding *b;
 114
 115         LIST_FOREACH(by_unit, b, first)
 116                 cgroup_bonding_trim(b, delete_root);
 117 }
 118
 119 int cgroup_bonding_install(CGroupBonding *b, pid_t pid) {
 120         int r;
 121
 122         assert(b);
 123         assert(pid >= 0);
 124
 125         if ((r = cg_create_and_attach(b->controller, b->path, pid)) < 0)
 126                 return r;
 127
 128         b->realized = true;
 129         return 0;
 130 }
 131
 132 int cgroup_bonding_install_list(CGroupBonding *first, pid_t pid) {
 133         CGroupBonding *b;
 134         int r;
 135
 136         LIST_FOREACH(by_unit, b, first)
 137                 if ((r = cgroup_bonding_install(b, pid)) < 0 && b->essential)
 138                         return r;
 139
 140         return 0;
 141 }
 142
 143 int cgroup_bonding_set_group_access(CGroupBonding *b, mode_t mode, uid_t uid, gid_t gid) {
 144         assert(b);
 145
 146         if (!b->realized)
 147                 return -EINVAL;
 148
 149         return cg_set_group_access(b->controller, b->path, mode, uid, gid);
 150 }
 151
 152 int cgroup_bonding_set_group_access_list(CGroupBonding *first, mode_t mode, uid_t uid, gid_t gid) {
 153         CGroupBonding *b;
 154         int r;
 155
 156         LIST_FOREACH(by_unit, b, first) {
 157                 r = cgroup_bonding_set_group_access(b, mode, uid, gid);
 158                 if (r < 0)
 159                         return r;
 160         }
 161
 162         return 0;
 163 }
 164
 165 int cgroup_bonding_set_task_access(CGroupBonding *b, mode_t mode, uid_t uid, gid_t gid) {
 166         assert(b);
 167
 168         if (!b->realized)
 169                 return -EINVAL;
 170
 171         return cg_set_task_access(b->controller, b->path, mode, uid, gid);
 172 }
 173
 174 int cgroup_bonding_set_task_access_list(CGroupBonding *first, mode_t mode, uid_t uid, gid_t gid) {
 175         CGroupBonding *b;
 176         int r;
 177
 178         LIST_FOREACH(by_unit, b, first) {
 179                 r = cgroup_bonding_set_task_access(b, mode, uid, gid);
 180                 if (r < 0)
 181                         return r;
 182         }
 183
 184         return 0;
 185 }
 186
 187 int cgroup_bonding_kill(CGroupBonding *b, int sig, bool sigcont, Set *s) {
 188         assert(b);
 189         assert(sig >= 0);
 190
 191         /* Don't kill cgroups that aren't ours */
 192         if (!b->ours)
 193                 return 0;
 194
 195         return cg_kill_recursive(b->controller, b->path, sig, sigcont, true, false, s);
 196 }
 197
 198 int cgroup_bonding_kill_list(CGroupBonding *first, int sig, bool sigcont, Set *s) {
 199         CGroupBonding *b;
 200         Set *allocated_set = NULL;
 201         int ret = -EAGAIN, r;
 202
 203         if (!s)
 204                 if (!(s = allocated_set = set_new(trivial_hash_func, trivial_compare_func)))
 205                         return -ENOMEM;
 206
 207         LIST_FOREACH(by_unit, b, first) {
 208                 if ((r = cgroup_bonding_kill(b, sig, sigcont, s)) < 0) {
 209                         if (r == -EAGAIN || r == -ESRCH)
 210                                 continue;
 211
 212                         ret = r;
 213                         goto finish;
 214                 }
 215
 216                 if (ret < 0 || r > 0)
 217                         ret = r;
 218         }
 219
 220 finish:
 221         if (allocated_set)
 222                 set_free(allocated_set);
 223
 224         return ret;
 225 }
 226
 227 /* Returns 1 if the group is empty, 0 if it is not, -EAGAIN if we
 228  * cannot know */
 229 int cgroup_bonding_is_empty(CGroupBonding *b) {
 230         int r;
 231
 232         assert(b);
 233
 234         if ((r = cg_is_empty_recursive(b->controller, b->path, true)) < 0)
 235                 return r;
 236
 237         /* If it is empty it is empty */
 238         if (r > 0)
 239                 return 1;
 240
 241         /* It's not only us using this cgroup, so we just don't know */
 242         return b->ours ? 0 : -EAGAIN;
 243 }
 244
 245 int cgroup_bonding_is_empty_list(CGroupBonding *first) {
 246         CGroupBonding *b;
 247
 248         LIST_FOREACH(by_unit, b, first) {
 249                 int r;
 250
 251                 if ((r = cgroup_bonding_is_empty(b)) < 0) {
 252                         /* If this returned -EAGAIN, then we don't know if the
 253                          * group is empty, so let's see if another group can
 254                          * tell us */
 255
 256                         if (r != -EAGAIN)
 257                                 return r;
 258                 } else
 259                         return r;
 260         }
 261
 262         return -EAGAIN;
 263 }
 264
 265 int manager_setup_cgroup(Manager *m) {
 266         char *current = NULL, *path = NULL;
 267         int r;
 268         char suffix[32];
 269
 270         assert(m);
 271
 272         /* 0. Be nice to Ingo Molnar #628004 */
 273         if (path_is_mount_point("/sys/fs/cgroup/systemd", false) <= 0) {
 274                 log_warning("No control group support available, not creating root group.");
 275                 return 0;
 276         }
 277
 278         /* 1. Determine hierarchy */
 279         if ((r = cg_get_by_pid(SYSTEMD_CGROUP_CONTROLLER, 0, &current)) < 0) {
 280                 log_error("Cannot determine cgroup we are running in: %s", strerror(-r));
 281                 goto finish;
 282         }
 283
 284         if (m->running_as == MANAGER_SYSTEM)
 285                 strcpy(suffix, "/system");
 286         else {
 287                 snprintf(suffix, sizeof(suffix), "/systemd-%lu", (unsigned long) getpid());
 288                 char_array_0(suffix);
 289         }
 290
 291         free(m->cgroup_hierarchy);
 292         if (endswith(current, suffix)) {
 293                 /* We probably got reexecuted and can continue to use our root cgroup */
 294                 m->cgroup_hierarchy = current;
 295                 current = NULL;
 296
 297         } else {
 298                 /* We need a new root cgroup */
 299                 m->cgroup_hierarchy = NULL;
 300                 if (asprintf(&m->cgroup_hierarchy, "%s%s", streq(current, "/") ? "" : current, suffix) < 0) {
 301                         log_error("Out of memory");
 302                         r = -ENOMEM;
 303                         goto finish;
 304                 }
 305         }
 306
 307         /* 2. Show data */
 308         if ((r = cg_get_path(SYSTEMD_CGROUP_CONTROLLER, m->cgroup_hierarchy, NULL, &path)) < 0) {
 309                 log_error("Cannot find cgroup mount point: %s", strerror(-r));
 310                 goto finish;
 311         }
 312
 313         log_debug("Using cgroup controller " SYSTEMD_CGROUP_CONTROLLER ". File system hierarchy is at %s.", path);
 314
 315         /* 3. Install agent */
 316         if ((r = cg_install_release_agent(SYSTEMD_CGROUP_CONTROLLER, SYSTEMD_CGROUP_AGENT_PATH)) < 0)
 317                 log_warning("Failed to install release agent, ignoring: %s", strerror(-r));
 318         else if (r > 0)
 319                 log_debug("Installed release agent.");
 320         else
 321                 log_debug("Release agent already installed.");
 322
 323         /* 4. Realize the group */
 324         if ((r = cg_create_and_attach(SYSTEMD_CGROUP_CONTROLLER, m->cgroup_hierarchy, 0)) < 0) {
 325                 log_error("Failed to create root cgroup hierarchy: %s", strerror(-r));
 326                 goto finish;
 327         }
 328
 329         /* 5. And pin it, so that it cannot be unmounted */
 330         if (m->pin_cgroupfs_fd >= 0)
 331                 close_nointr_nofail(m->pin_cgroupfs_fd);
 332
 333         if ((m->pin_cgroupfs_fd = open(path, O_RDONLY|O_CLOEXEC|O_DIRECTORY|O_NOCTTY|O_NONBLOCK)) < 0) {
 334                 log_error("Failed to open pin file: %m");
 335                 r = -errno;
 336                 goto finish;
 337         }
 338
 339         log_debug("Created root group.");
 340
 341 finish:
 342         free(current);
 343         free(path);
 344
 345         return r;
 346 }
 347
 348 void manager_shutdown_cgroup(Manager *m, bool delete) {
 349         assert(m);
 350
 351         if (delete && m->cgroup_hierarchy)
 352                 cg_delete(SYSTEMD_CGROUP_CONTROLLER, m->cgroup_hierarchy);
 353
 354         if (m->pin_cgroupfs_fd >= 0) {
 355                 close_nointr_nofail(m->pin_cgroupfs_fd);
 356                 m->pin_cgroupfs_fd = -1;
 357         }
 358
 359         free(m->cgroup_hierarchy);
 360         m->cgroup_hierarchy = NULL;
 361 }
 362
 363 int cgroup_notify_empty(Manager *m, const char *group) {
 364         CGroupBonding *l, *b;
 365
 366         assert(m);
 367         assert(group);
 368
 369         if (!(l = hashmap_get(m->cgroup_bondings, group)))
 370                 return 0;
 371
 372         LIST_FOREACH(by_path, b, l) {
 373                 int t;
 374
 375                 if (!b->unit)
 376                         continue;
 377
 378                 if ((t = cgroup_bonding_is_empty_list(b)) < 0) {
 379
 380                         /* If we don't know, we don't know */
 381                         if (t != -EAGAIN)
 382                                 log_warning("Failed to check whether cgroup is empty: %s", strerror(errno));
 383
 384                         continue;
 385                 }
 386
 387                 if (t > 0)
 388                         if (UNIT_VTABLE(b->unit)->cgroup_notify_empty)
 389                                 UNIT_VTABLE(b->unit)->cgroup_notify_empty(b->unit);
 390         }
 391
 392         return 0;
 393 }
 394
 395 Unit* cgroup_unit_by_pid(Manager *m, pid_t pid) {
 396         CGroupBonding *l, *b;
 397         char *group = NULL;
 398
 399         assert(m);
 400
 401         if (pid <= 1)
 402                 return NULL;
 403
 404         if (cg_get_by_pid(SYSTEMD_CGROUP_CONTROLLER, pid, &group) < 0)
 405                 return NULL;
 406
 407         l = hashmap_get(m->cgroup_bondings, group);
 408
 409         if (!l) {
 410                 char *slash;
 411
 412                 while ((slash = strrchr(group, '/'))) {
 413                         if (slash == group)
 414                                 break;
 415
 416                         *slash = 0;
 417
 418                         if ((l = hashmap_get(m->cgroup_bondings, group)))
 419                                 break;
 420                 }
 421         }
 422
 423         free(group);
 424
 425         LIST_FOREACH(by_path, b, l) {
 426
 427                 if (!b->unit)
 428                         continue;
 429
 430                 if (b->ours)
 431                         return b->unit;
 432         }
 433
 434         return NULL;
 435 }
 436
 437 CGroupBonding *cgroup_bonding_find_list(CGroupBonding *first, const char *controller) {
 438         CGroupBonding *b;
 439
 440         assert(controller);
 441
 442         LIST_FOREACH(by_unit, b, first)
 443                 if (streq(b->controller, controller))
 444                         return b;
 445
 446         return NULL;
 447 }
 448
 449 char *cgroup_bonding_to_string(CGroupBonding *b) {
 450         char *r;
 451
 452         assert(b);
 453
 454         if (asprintf(&r, "%s:%s", b->controller, b->path) < 0)
 455                 return NULL;
 456
 457         return r;
 458 }
 459
 460 pid_t cgroup_bonding_search_main_pid(CGroupBonding *b) {
 461         FILE *f;
 462         pid_t pid = 0, npid, mypid;
 463
 464         assert(b);
 465
 466         if (!b->ours)
 467                 return 0;
 468
 469         if (cg_enumerate_processes(b->controller, b->path, &f) < 0)
 470                 return 0;
 471
 472         mypid = getpid();
 473
 474         while (cg_read_pid(f, &npid) > 0)  {
 475                 pid_t ppid;
 476
 477                 if (npid == pid)
 478                         continue;
 479
 480                 /* Ignore processes that aren't our kids */
 481                 if (get_parent_of_pid(npid, &ppid) >= 0 && ppid != mypid)
 482                         continue;
 483
 484                 if (pid != 0) {
 485                         /* Dang, there's more than one daemonized PID
 486                         in this group, so we don't know what process
 487                         is the main process. */
 488                         pid = 0;
 489                         break;
 490                 }
 491
 492                 pid = npid;
 493         }
 494
 495         fclose(f);
 496
 497         return pid;
 498 }
 499
 500 pid_t cgroup_bonding_search_main_pid_list(CGroupBonding *first) {
 501         CGroupBonding *b;
 502         pid_t pid;
 503
 504         /* Try to find a main pid from this cgroup, but checking if
 505          * there's only one PID in the cgroup and returning it. Later
 506          * on we might want to add additional, smarter heuristics
 507          * here. */
 508
 509         LIST_FOREACH(by_unit, b, first)
 510                 if ((pid = cgroup_bonding_search_main_pid(b)) != 0)
 511                         return pid;
 512
 513         return 0;
 514
 515 }