cgroup.c revision e99e38bbdcca3fe5956823bdb3d38544ccf93221
/*-*- Mode: C; c-basic-offset: 8 -*-*/
/***
This file is part of systemd.
Copyright 2010 Lennart Poettering
systemd is free software; you can redistribute it and/or modify it
under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
systemd is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
General Public License for more details.
You should have received a copy of the GNU General Public License
along with systemd; If not, see <http://www.gnu.org/licenses/>.
***/
#include <errno.h>
#include <assert.h>
#include <unistd.h>
#include <sys/types.h>
#include <signal.h>
#include <sys/mount.h>
#include "cgroup.h"
#include "log.h"
static int translate_error(int error, int _errno) {
switch (error) {
case ECGROUPNOTCOMPILED:
case ECGROUPNOTMOUNTED:
case ECGROUPNOTEXIST:
case ECGROUPNOTCREATED:
return -ENOENT;
case ECGINVAL:
return -EINVAL;
case ECGROUPNOTALLOWED:
return -EPERM;
case ECGOTHER:
return -_errno;
}
return -EIO;
}
int cgroup_bonding_realize(CGroupBonding *b) {
int r;
assert(b);
assert(b->path);
assert(b->controller);
if (b->cgroup)
return 0;
if (!(b->cgroup = cgroup_new_cgroup(b->path)))
return -ENOMEM;
if (!cgroup_add_controller(b->cgroup, b->controller)) {
r = -ENOMEM;
goto fail;
}
if (b->inherit)
r = cgroup_create_cgroup_from_parent(b->cgroup, true);
else
r = cgroup_create_cgroup(b->cgroup, true);
if (r != 0) {
r = translate_error(r, errno);
goto fail;
}
return 0;
fail:
cgroup_free(&b->cgroup);
b->cgroup = NULL;
return r;
}
int cgroup_bonding_realize_list(CGroupBonding *first) {
CGroupBonding *b;
LIST_FOREACH(by_unit, b, first) {
int r;
if ((r = cgroup_bonding_realize(b)) < 0)
return r;
}
return 0;
}
void cgroup_bonding_free(CGroupBonding *b) {
assert(b);
if (b->unit) {
CGroupBonding *f;
LIST_REMOVE(CGroupBonding, by_unit, b->unit->meta.cgroup_bondings, b);
assert_se(f = hashmap_get(b->unit->meta.manager->cgroup_bondings, b->path));
LIST_REMOVE(CGroupBonding, by_path, f, b);
if (f)
hashmap_replace(b->unit->meta.manager->cgroup_bondings, b->path, f);
else
hashmap_remove(b->unit->meta.manager->cgroup_bondings, b->path);
}
if (b->cgroup) {
if (b->only_us && b->clean_up && cgroup_bonding_is_empty(b) > 0)
cgroup_delete_cgroup_ext(b->cgroup, true);
cgroup_free(&b->cgroup);
}
free(b->controller);
free(b->path);
free(b);
}
void cgroup_bonding_free_list(CGroupBonding *first) {
CGroupBonding *b, *n;
LIST_FOREACH_SAFE(by_unit, b, n, first)
cgroup_bonding_free(b);
}
int cgroup_bonding_install(CGroupBonding *b, pid_t pid) {
int r;
assert(b);
assert(pid >= 0);
if (pid == 0)
pid = getpid();
if (!b->cgroup)
return -ENOENT;
if ((r = cgroup_attach_task_pid(b->cgroup, pid)))
return translate_error(r, errno);
return 0;
}
int cgroup_bonding_install_list(CGroupBonding *first, pid_t pid) {
CGroupBonding *b;
LIST_FOREACH(by_unit, b, first) {
int r;
if ((r = cgroup_bonding_install(b, pid)) < 0)
return r;
}
return 0;
}
int cgroup_bonding_kill(CGroupBonding *b, int sig) {
int r;
Set *s;
bool done;
bool killed = false;
assert(b);
assert(sig > 0);
if (!b->only_us)
return -EAGAIN;
if (!(s = set_new(trivial_hash_func, trivial_compare_func)))
return -ENOMEM;
do {
void *iterator;
pid_t pid;
done = true;
if ((r = cgroup_get_task_begin(b->path, b->controller, &iterator, &pid)) != 0) {
if (r == ECGEOF) {
r = 0;
goto kill_done;
} else {
r = translate_error(r, errno);
break;
}
}
for (;;) {
if (set_get(s, INT_TO_PTR(pid)) != INT_TO_PTR(pid)) {
/* If we haven't killed this process
* yet, kill it */
if (kill(pid, sig) < 0 && errno != ESRCH) {
r = -errno;
break;
}
killed = true;
done = false;
if ((r = set_put(s, INT_TO_PTR(pid))) < 0)
break;
}
if ((r = cgroup_get_task_next(&iterator, &pid)) != 0) {
if (r == ECGEOF)
r = 0;
else
r = translate_error(r, errno);
break;
}
}
kill_done:
assert_se(cgroup_get_task_end(&iterator) == 0);
/* To avoid racing against processes which fork
* quicker than we can kill them we repeat this until
* no new pids need to be killed. */
} while (!done && r >= 0);
set_free(s);
if (r < 0)
return r;
return killed ? 0 : -ESRCH;
}
int cgroup_bonding_kill_list(CGroupBonding *first, int sig) {
CGroupBonding *b;
int r = -EAGAIN;
LIST_FOREACH(by_unit, b, first) {
if ((r = cgroup_bonding_kill(b, sig)) < 0) {
if (r == -EAGAIN || -ESRCH)
continue;
return r;
}
return 0;
}
return r;
}
/* Returns 1 if the group is empty, 0 if it is not, -EAGAIN if we
* cannot know */
int cgroup_bonding_is_empty(CGroupBonding *b) {
void *iterator;
pid_t pid;
int r;
assert(b);
r = cgroup_get_task_begin(b->path, b->controller, &iterator, &pid);
if (r == 0 || r == ECGEOF)
cgroup_get_task_end(&iterator);
/* Hmm, no PID in this group? Then it is definitely empty */
if (r == ECGEOF)
return 1;
/* Some error? Let's return it */
if (r != 0)
return translate_error(r, errno);
/* It's not empty, and we are the only user, then it is
* definitely not empty */
if (b->only_us)
return 0;
/* There are PIDs in the group but we aren't the only users,
* hence we cannot say */
return -EAGAIN;
}
int cgroup_bonding_is_empty_list(CGroupBonding *first) {
CGroupBonding *b;
LIST_FOREACH(by_unit, b, first) {
int r;
if ((r = cgroup_bonding_is_empty(b)) < 0) {
/* If this returned -EAGAIN, then we don't know if the
* group is empty, so let's see if another group can
* tell us */
if (r != -EAGAIN)
return r;
} else
return r;
}
return -EAGAIN;
}
static int install_release_agent(Manager *m, const char *mount_point) {
char *p, *c, *sc;
int r;
assert(m);
assert(mount_point);
if (asprintf(&p, "%s/release_agent", mount_point) < 0)
return -ENOMEM;
if ((r = read_one_line_file(p, &c)) < 0) {
free(p);
return r;
}
sc = strstrip(c);
if (sc[0] == 0) {
if ((r = write_one_line_file(p, CGROUP_AGENT_PATH "\n" )) < 0) {
free(p);
free(c);
return r;
}
} else if (!streq(sc, CGROUP_AGENT_PATH)) {
free(p);
free(c);
return -EEXIST;
}
free(c);
free(p);
if (asprintf(&p, "%s/notify_on_release", mount_point) < 0)
return -ENOMEM;
if ((r = read_one_line_file(p, &c)) < 0) {
free(p);
return r;
}
sc = strstrip(c);
if (streq(sc, "0")) {
if ((r = write_one_line_file(p, "1\n")) < 0) {
free(p);
free(c);
return r;
}
} else if (!streq(sc, "1")) {
free(p);
free(c);
return -EIO;
}
free(p);
free(c);
return 0;
}
static int create_hierarchy_cgroup(Manager *m) {
struct cgroup *cg;
int r;
assert(m);
if (!(cg = cgroup_new_cgroup(m->cgroup_hierarchy)))
return -ENOMEM;
if (!(cgroup_add_controller(cg, m->cgroup_controller))) {
r = -ENOMEM;
goto finish;
}
if ((r = cgroup_create_cgroup(cg, true)) != 0) {
log_error("Failed to create cgroup hierarchy group: %s", cgroup_strerror(r));
r = translate_error(r, errno);
goto finish;
}
if ((r = cgroup_attach_task(cg)) != 0) {
log_error("Failed to add ourselves to hierarchy group: %s", cgroup_strerror(r));
r = translate_error(r, errno);
goto finish;
}
r = 0;
finish:
cgroup_free(&cg);
return r;
}
int manager_setup_cgroup(Manager *m) {
char *mp, *cp;
int r;
pid_t pid;
char suffix[32];
assert(m);
if ((r = cgroup_init()) != 0) {
log_error("Failed to initialize libcg: %s", cgroup_strerror(r));
return translate_error(r, errno);
}
free(m->cgroup_controller);
if (!(m->cgroup_controller = strdup("debug")))
return -ENOMEM;
if ((r = cgroup_get_subsys_mount_point(m->cgroup_controller, &mp)))
return translate_error(r, errno);
pid = getpid();
if ((r = cgroup_get_current_controller_path(pid, m->cgroup_controller, &cp))) {
free(mp);
return translate_error(r, errno);
}
snprintf(suffix, sizeof(suffix), "/systemd-%u", (unsigned) pid);
char_array_0(suffix);
free(m->cgroup_hierarchy);
if (endswith(cp, suffix))
/* We probably got reexecuted and can continue to use our root cgroup */
m->cgroup_hierarchy = cp;
else {
/* We need a new root cgroup */
m->cgroup_hierarchy = NULL;
r = asprintf(&m->cgroup_hierarchy, "%s%s", streq(cp, "/") ? "" : cp, suffix);
free(cp);
if (r < 0) {
free(mp);
return -ENOMEM;
}
}
log_debug("Using cgroup controller <%s>, hierarchy mounted at <%s>, using root group <%s>.",
m->cgroup_controller,
mp,
m->cgroup_hierarchy);
if ((r = install_release_agent(m, mp)) < 0)
log_warning("Failed to install release agent, ignoring: %s", strerror(-r));
else
log_debug("Installed release agent, or already installed.");
free(mp);
if ((r = create_hierarchy_cgroup(m)) < 0)
log_error("Failed to create root cgroup hierarchy: %s", strerror(-r));
else
log_debug("Created root group.");
return r;
}
int manager_shutdown_cgroup(Manager *m, bool delete) {
struct cgroup *cg;
int r;
assert(m);
if (!m->cgroup_hierarchy)
return 0;
if (!(cg = cgroup_new_cgroup(m->cgroup_hierarchy)))
return -ENOMEM;
if (!(cgroup_add_controller(cg, m->cgroup_controller))) {
r = -ENOMEM;
goto finish;
}
/* Often enough we won't be able to delete the cgroup we
* ourselves are in, hence ignore all errors here */
if (delete)
cgroup_delete_cgroup_ext(cg, CGFLAG_DELETE_IGNORE_MIGRATION|CGFLAG_DELETE_RECURSIVE);
r = 0;
finish:
cgroup_free(&cg);
return r;
}
int cgroup_notify_empty(Manager *m, const char *group) {
CGroupBonding *l, *b;
assert(m);
assert(group);
if (!(l = hashmap_get(m->cgroup_bondings, group)))
return 0;
LIST_FOREACH(by_path, b, l) {
int t;
if (!b->unit)
continue;
if ((t = cgroup_bonding_is_empty_list(b)) < 0) {
/* If we don't know, we don't know */
if (t != -EAGAIN)
log_warning("Failed to check whether cgroup is empty: %s", strerror(errno));
continue;
}
if (t > 0)
if (UNIT_VTABLE(b->unit)->cgroup_notify_empty)
UNIT_VTABLE(b->unit)->cgroup_notify_empty(b->unit);
}
return 0;
}
CGroupBonding *cgroup_bonding_find_list(CGroupBonding *first, const char *controller) {
CGroupBonding *b;
assert(controller);
LIST_FOREACH(by_unit, b, first)
if (streq(b->controller, controller))
return b;
return NULL;
}
char *cgroup_bonding_to_string(CGroupBonding *b) {
char *r;
assert(b);
if (asprintf(&r, "%s:%s", b->controller, b->path) < 0)
return NULL;
return r;
}