src/cgroup.c

   1 /*-*- Mode: C; c-basic-offset: 8 -*-*/
   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         if ((r = cg_create(b->controller, b->path)) < 0)
  45                 return r;
  46
  47         b->realized = true;
  48
  49         if (b->only_us && b->clean_up)
  50                 cg_trim(b->controller, b->path, false);
  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)
  61                         return r;
  62
  63         return 0;
  64 }
  65
  66 void cgroup_bonding_free(CGroupBonding *b) {
  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                 assert_se(f = hashmap_get(b->unit->meta.manager->cgroup_bondings, b->path));
  75                 LIST_REMOVE(CGroupBonding, by_path, f, b);
  76
  77                 if (f)
  78                         hashmap_replace(b->unit->meta.manager->cgroup_bondings, b->path, f);
  79                 else
  80                         hashmap_remove(b->unit->meta.manager->cgroup_bondings, b->path);
  81         }
  82
  83         if (b->realized && b->only_us && b->clean_up) {
  84
  85                 if (cgroup_bonding_is_empty(b) > 0)
  86                         cg_delete(b->controller, b->path);
  87                 else
  88                         cg_trim(b->controller, b->path, false);
  89         }
  90
  91         free(b->controller);
  92         free(b->path);
  93         free(b);
  94 }
  95
  96 void cgroup_bonding_free_list(CGroupBonding *first) {
  97         CGroupBonding *b, *n;
  98
  99         LIST_FOREACH_SAFE(by_unit, b, n, first)
 100                 cgroup_bonding_free(b);
 101 }
 102
 103 void cgroup_bonding_trim(CGroupBonding *b, bool delete_root) {
 104         assert(b);
 105
 106         if (b->realized && b->only_us && b->clean_up)
 107                 cg_trim(b->controller, b->path, delete_root);
 108 }
 109
 110 void cgroup_bonding_trim_list(CGroupBonding *first, bool delete_root) {
 111         CGroupBonding *b;
 112
 113         LIST_FOREACH(by_unit, b, first)
 114                 cgroup_bonding_trim(b, delete_root);
 115 }
 116
 117 int cgroup_bonding_install(CGroupBonding *b, pid_t pid) {
 118         int r;
 119
 120         assert(b);
 121         assert(pid >= 0);
 122
 123         if ((r = cg_create_and_attach(b->controller, b->path, pid)) < 0)
 124                 return r;
 125
 126         b->realized = true;
 127         return 0;
 128 }
 129
 130 int cgroup_bonding_install_list(CGroupBonding *first, pid_t pid) {
 131         CGroupBonding *b;
 132         int r;
 133
 134         LIST_FOREACH(by_unit, b, first)
 135                 if ((r = cgroup_bonding_install(b, pid)) < 0)
 136                         return r;
 137
 138         return 0;
 139 }
 140
 141 int cgroup_bonding_kill(CGroupBonding *b, int sig) {
 142         int r;
 143
 144         assert(b);
 145         assert(sig >= 0);
 146
 147         if ((r = cgroup_bonding_realize(b)) < 0)
 148                 return r;
 149
 150         assert(b->realized);
 151
 152         return cg_kill_recursive(b->controller, b->path, sig, true, false);
 153 }
 154
 155 int cgroup_bonding_kill_list(CGroupBonding *first, int sig) {
 156         CGroupBonding *b;
 157         int r = -EAGAIN;
 158
 159         LIST_FOREACH(by_unit, b, first) {
 160                 if ((r = cgroup_bonding_kill(b, sig)) < 0) {
 161                         if (r == -EAGAIN || r == -ESRCH)
 162                                 continue;
 163
 164                         return r;
 165                 }
 166
 167                 return 0;
 168         }
 169
 170         return r;
 171 }
 172
 173 /* Returns 1 if the group is empty, 0 if it is not, -EAGAIN if we
 174  * cannot know */
 175 int cgroup_bonding_is_empty(CGroupBonding *b) {
 176         int r;
 177
 178         assert(b);
 179
 180         if ((r = cg_is_empty_recursive(b->controller, b->path, true)) < 0)
 181                 return r;
 182
 183         /* If it is empty it is empty */
 184         if (r > 0)
 185                 return 1;
 186
 187         /* It's not only us using this cgroup, so we just don't know */
 188         return b->only_us ? 0 : -EAGAIN;
 189 }
 190
 191 int cgroup_bonding_is_empty_list(CGroupBonding *first) {
 192         CGroupBonding *b;
 193
 194         LIST_FOREACH(by_unit, b, first) {
 195                 int r;
 196
 197                 if ((r = cgroup_bonding_is_empty(b)) < 0) {
 198                         /* If this returned -EAGAIN, then we don't know if the
 199                          * group is empty, so let's see if another group can
 200                          * tell us */
 201
 202                         if (r != -EAGAIN)
 203                                 return r;
 204                 } else
 205                         return r;
 206         }
 207
 208         return -EAGAIN;
 209 }
 210
 211 int manager_setup_cgroup(Manager *m) {
 212         char *current = NULL, *path = NULL;
 213         int r;
 214         char suffix[32];
 215
 216         assert(m);
 217
 218         /* 1. Determine hierarchy */
 219         if ((r = cg_get_by_pid(SYSTEMD_CGROUP_CONTROLLER, 0, &current)) < 0)
 220                 goto finish;
 221
 222         snprintf(suffix, sizeof(suffix), "/systemd-%lu", (unsigned long) getpid());
 223         char_array_0(suffix);
 224
 225         free(m->cgroup_hierarchy);
 226         if (endswith(current, suffix)) {
 227                 /* We probably got reexecuted and can continue to use our root cgroup */
 228                 m->cgroup_hierarchy = current;
 229                 current = NULL;
 230
 231         } else {
 232                 /* We need a new root cgroup */
 233                 m->cgroup_hierarchy = NULL;
 234                 if (asprintf(&m->cgroup_hierarchy, "%s%s", streq(current, "/") ? "" : current, suffix) < 0) {
 235                         r = -ENOMEM;
 236                         goto finish;
 237                 }
 238         }
 239
 240         /* 2. Show data */
 241         if ((r = cg_get_path(SYSTEMD_CGROUP_CONTROLLER, m->cgroup_hierarchy, NULL, &path)) < 0)
 242                 goto finish;
 243
 244         log_debug("Using cgroup controller " SYSTEMD_CGROUP_CONTROLLER ". File system hierarchy is at %s.", path);
 245
 246         /* 3. Install agent */
 247         if ((r = cg_install_release_agent(SYSTEMD_CGROUP_CONTROLLER, CGROUP_AGENT_PATH)) < 0)
 248                 log_warning("Failed to install release agent, ignoring: %s", strerror(-r));
 249         else if (r > 0)
 250                 log_debug("Installed release agent.");
 251         else
 252                 log_debug("Release agent already installed.");
 253
 254         /* 4. Realize the group */
 255         if ((r = cg_create_and_attach(SYSTEMD_CGROUP_CONTROLLER, m->cgroup_hierarchy, 0)) < 0) {
 256                 log_error("Failed to create root cgroup hierarchy: %s", strerror(-r));
 257                 goto finish;
 258         }
 259
 260         /* 5. And pin it, so that it cannot be unmounted */
 261         if (m->pin_cgroupfs_fd >= 0)
 262                 close_nointr_nofail(m->pin_cgroupfs_fd);
 263
 264         if ((m->pin_cgroupfs_fd = open(path, O_RDONLY|O_CLOEXEC|O_DIRECTORY|O_NOCTTY|O_NONBLOCK)) < 0) {
 265                 r = -errno;
 266                 goto finish;
 267         }
 268
 269         log_debug("Created root group.");
 270
 271 finish:
 272         free(current);
 273         free(path);
 274
 275         return r;
 276 }
 277
 278 void manager_shutdown_cgroup(Manager *m, bool delete) {
 279         assert(m);
 280
 281         if (delete && m->cgroup_hierarchy)
 282                 cg_delete(SYSTEMD_CGROUP_CONTROLLER, m->cgroup_hierarchy);
 283
 284         if (m->pin_cgroupfs_fd >= 0) {
 285                 close_nointr_nofail(m->pin_cgroupfs_fd);
 286                 m->pin_cgroupfs_fd = -1;
 287         }
 288
 289         free(m->cgroup_hierarchy);
 290         m->cgroup_hierarchy = NULL;
 291 }
 292
 293 int cgroup_notify_empty(Manager *m, const char *group) {
 294         CGroupBonding *l, *b;
 295
 296         assert(m);
 297         assert(group);
 298
 299         if (!(l = hashmap_get(m->cgroup_bondings, group)))
 300                 return 0;
 301
 302         LIST_FOREACH(by_path, b, l) {
 303                 int t;
 304
 305                 if (!b->unit)
 306                         continue;
 307
 308                 if ((t = cgroup_bonding_is_empty_list(b)) < 0) {
 309
 310                         /* If we don't know, we don't know */
 311                         if (t != -EAGAIN)
 312                                 log_warning("Failed to check whether cgroup is empty: %s", strerror(errno));
 313
 314                         continue;
 315                 }
 316
 317                 if (t > 0)
 318                         if (UNIT_VTABLE(b->unit)->cgroup_notify_empty)
 319                                 UNIT_VTABLE(b->unit)->cgroup_notify_empty(b->unit);
 320         }
 321
 322         return 0;
 323 }
 324
 325 Unit* cgroup_unit_by_pid(Manager *m, pid_t pid) {
 326         CGroupBonding *l, *b;
 327         char *group = NULL;
 328
 329         assert(m);
 330
 331         if (pid <= 1)
 332                 return NULL;
 333
 334         if (cg_get_by_pid(SYSTEMD_CGROUP_CONTROLLER, pid, &group) < 0)
 335                 return NULL;
 336
 337         l = hashmap_get(m->cgroup_bondings, group);
 338         free(group);
 339
 340         LIST_FOREACH(by_path, b, l) {
 341
 342                 if (!b->unit)
 343                         continue;
 344
 345                 if (b->only_us)
 346                         return b->unit;
 347         }
 348
 349         return NULL;
 350 }
 351
 352 CGroupBonding *cgroup_bonding_find_list(CGroupBonding *first, const char *controller) {
 353         CGroupBonding *b;
 354
 355         assert(controller);
 356
 357         LIST_FOREACH(by_unit, b, first)
 358                 if (streq(b->controller, controller))
 359                         return b;
 360
 361         return NULL;
 362 }
 363
 364 char *cgroup_bonding_to_string(CGroupBonding *b) {
 365         char *r;
 366
 367         assert(b);
 368
 369         if (asprintf(&r, "%s:%s", b->controller, b->path) < 0)
 370                 return NULL;
 371
 372         return r;
 373 }