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Systemd/src/core/swap.c
Franck Bui f75f613d25 core: reduce the number of stalled PIDs from the watched processes list when possible 
Some PIDs can remain in the watched list even though their processes have
exited since a long time. It can easily happen if the main process of a forking
service manages to spawn a child before the control process exits for example.

However when a pid is about to be mapped to a unit by calling unit_watch_pid(),
the caller usually knows if the pid should belong to this unit exclusively: if
we just forked() off a child, then we can be sure that its PID is otherwise
unused. In this case we take this opportunity to remove any stalled PIDs from
the watched process list.

If we learnt about a PID in any other form (for example via PID file, via
searching, MAINPID= and so on), then we can't assume anything.
2019-03-20 10:51:49 +01:00

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/* SPDX-License-Identifier: LGPL-2.1+ */
#include <errno.h>
#include <sys/epoll.h>
#include <sys/stat.h>
#include <unistd.h>
#include "sd-device.h"
#include "alloc-util.h"
#include "dbus-swap.h"
#include "dbus-unit.h"
#include "device-private.h"
#include "device-util.h"
#include "device.h"
#include "escape.h"
#include "exit-status.h"
#include "fd-util.h"
#include "format-util.h"
#include "fstab-util.h"
#include "parse-util.h"
#include "path-util.h"
#include "process-util.h"
#include "serialize.h"
#include "special.h"
#include "string-table.h"
#include "string-util.h"
#include "swap.h"
#include "unit-name.h"
#include "unit.h"
#include "virt.h"
static const UnitActiveState state_translation_table[_SWAP_STATE_MAX] = {
[SWAP_DEAD] = UNIT_INACTIVE,
[SWAP_ACTIVATING] = UNIT_ACTIVATING,
[SWAP_ACTIVATING_DONE] = UNIT_ACTIVE,
[SWAP_ACTIVE] = UNIT_ACTIVE,
[SWAP_DEACTIVATING] = UNIT_DEACTIVATING,
[SWAP_DEACTIVATING_SIGTERM] = UNIT_DEACTIVATING,
[SWAP_DEACTIVATING_SIGKILL] = UNIT_DEACTIVATING,
[SWAP_FAILED] = UNIT_FAILED
};
static int swap_dispatch_timer(sd_event_source *source, usec_t usec, void *userdata);
static int swap_dispatch_io(sd_event_source *source, int fd, uint32_t revents, void *userdata);
static bool SWAP_STATE_WITH_PROCESS(SwapState state) {
return IN_SET(state,
SWAP_ACTIVATING,
SWAP_ACTIVATING_DONE,
SWAP_DEACTIVATING,
SWAP_DEACTIVATING_SIGTERM,
SWAP_DEACTIVATING_SIGKILL);
}
static void swap_unset_proc_swaps(Swap *s) {
assert(s);
if (!s->from_proc_swaps)
return;
s->parameters_proc_swaps.what = mfree(s->parameters_proc_swaps.what);
s->from_proc_swaps = false;
}
static int swap_set_devnode(Swap *s, const char *devnode) {
Hashmap *swaps;
Swap *first;
int r;
assert(s);
r = hashmap_ensure_allocated(&UNIT(s)->manager->swaps_by_devnode, &path_hash_ops);
if (r < 0)
return r;
swaps = UNIT(s)->manager->swaps_by_devnode;
if (s->devnode) {
first = hashmap_get(swaps, s->devnode);
LIST_REMOVE(same_devnode, first, s);
if (first)
hashmap_replace(swaps, first->devnode, first);
else
hashmap_remove(swaps, s->devnode);
s->devnode = mfree(s->devnode);
}
if (devnode) {
s->devnode = strdup(devnode);
if (!s->devnode)
return -ENOMEM;
first = hashmap_get(swaps, s->devnode);
LIST_PREPEND(same_devnode, first, s);
return hashmap_replace(swaps, first->devnode, first);
}
return 0;
}
static void swap_init(Unit *u) {
Swap *s = SWAP(u);
assert(s);
assert(UNIT(s)->load_state == UNIT_STUB);
s->timeout_usec = u->manager->default_timeout_start_usec;
s->exec_context.std_output = u->manager->default_std_output;
s->exec_context.std_error = u->manager->default_std_error;
s->parameters_proc_swaps.priority = s->parameters_fragment.priority = -1;
s->control_command_id = _SWAP_EXEC_COMMAND_INVALID;
u->ignore_on_isolate = true;
}
static void swap_unwatch_control_pid(Swap *s) {
assert(s);
if (s->control_pid <= 0)
return;
unit_unwatch_pid(UNIT(s), s->control_pid);
s->control_pid = 0;
}
static void swap_done(Unit *u) {
Swap *s = SWAP(u);
assert(s);
swap_unset_proc_swaps(s);
swap_set_devnode(s, NULL);
s->what = mfree(s->what);
s->parameters_fragment.what = mfree(s->parameters_fragment.what);
s->parameters_fragment.options = mfree(s->parameters_fragment.options);
s->exec_runtime = exec_runtime_unref(s->exec_runtime, false);
exec_command_done_array(s->exec_command, _SWAP_EXEC_COMMAND_MAX);
s->control_command = NULL;
dynamic_creds_unref(&s->dynamic_creds);
swap_unwatch_control_pid(s);
s->timer_event_source = sd_event_source_unref(s->timer_event_source);
}
static int swap_arm_timer(Swap *s, usec_t usec) {
int r;
assert(s);
if (s->timer_event_source) {
r = sd_event_source_set_time(s->timer_event_source, usec);
if (r < 0)
return r;
return sd_event_source_set_enabled(s->timer_event_source, SD_EVENT_ONESHOT);
}
if (usec == USEC_INFINITY)
return 0;
r = sd_event_add_time(
UNIT(s)->manager->event,
&s->timer_event_source,
CLOCK_MONOTONIC,
usec, 0,
swap_dispatch_timer, s);
if (r < 0)
return r;
(void) sd_event_source_set_description(s->timer_event_source, "swap-timer");
return 0;
}
static int swap_add_device_dependencies(Swap *s) {
assert(s);
if (!s->what)
return 0;
if (!s->from_fragment)
return 0;
if (is_device_path(s->what))
return unit_add_node_dependency(UNIT(s), s->what, MANAGER_IS_SYSTEM(UNIT(s)->manager), UNIT_BINDS_TO, UNIT_DEPENDENCY_FILE);
else
/* File based swap devices need to be ordered after
* systemd-remount-fs.service, since they might need a
* writable file system. */
return unit_add_dependency_by_name(UNIT(s), UNIT_AFTER, SPECIAL_REMOUNT_FS_SERVICE, true, UNIT_DEPENDENCY_FILE);
}
static int swap_add_default_dependencies(Swap *s) {
int r;
assert(s);
if (!UNIT(s)->default_dependencies)
return 0;
if (!MANAGER_IS_SYSTEM(UNIT(s)->manager))
return 0;
if (detect_container() > 0)
return 0;
/* swap units generated for the swap dev links are missing the
* ordering dep against the swap target. */
r = unit_add_dependency_by_name(UNIT(s), UNIT_BEFORE, SPECIAL_SWAP_TARGET, true, UNIT_DEPENDENCY_DEFAULT);
if (r < 0)
return r;
return unit_add_two_dependencies_by_name(UNIT(s), UNIT_BEFORE, UNIT_CONFLICTS, SPECIAL_UMOUNT_TARGET, true, UNIT_DEPENDENCY_DEFAULT);
}
static int swap_verify(Swap *s) {
_cleanup_free_ char *e = NULL;
int r;
if (UNIT(s)->load_state != UNIT_LOADED)
return 0;
r = unit_name_from_path(s->what, ".swap", &e);
if (r < 0)
return log_unit_error_errno(UNIT(s), r, "Failed to generate unit name from path: %m");
if (!unit_has_name(UNIT(s), e)) {
log_unit_error(UNIT(s), "Value of What= and unit name do not match, not loading.");
return -ENOEXEC;
}
if (s->exec_context.pam_name && s->kill_context.kill_mode != KILL_CONTROL_GROUP) {
log_unit_error(UNIT(s), "Unit has PAM enabled. Kill mode must be set to 'control-group'. Refusing to load.");
return -ENOEXEC;
}
return 0;
}
static int swap_load_devnode(Swap *s) {
_cleanup_(sd_device_unrefp) sd_device *d = NULL;
struct stat st;
const char *p;
int r;
assert(s);
if (stat(s->what, &st) < 0 || !S_ISBLK(st.st_mode))
return 0;
r = device_new_from_stat_rdev(&d, &st);
if (r < 0) {
log_unit_full(UNIT(s), r == -ENOENT ? LOG_DEBUG : LOG_WARNING, r,
"Failed to allocate device for swap %s: %m", s->what);
return 0;
}
if (sd_device_get_devname(d, &p) < 0)
return 0;
return swap_set_devnode(s, p);
}
static int swap_add_extras(Swap *s) {
int r;
assert(s);
if (UNIT(s)->fragment_path)
s->from_fragment = true;
if (!s->what) {
if (s->parameters_fragment.what)
s->what = strdup(s->parameters_fragment.what);
else if (s->parameters_proc_swaps.what)
s->what = strdup(s->parameters_proc_swaps.what);
else {
r = unit_name_to_path(UNIT(s)->id, &s->what);
if (r < 0)
return r;
}
if (!s->what)
return -ENOMEM;
}
path_simplify(s->what, false);
if (!UNIT(s)->description) {
r = unit_set_description(UNIT(s), s->what);
if (r < 0)
return r;
}
r = unit_require_mounts_for(UNIT(s), s->what, UNIT_DEPENDENCY_IMPLICIT);
if (r < 0)
return r;
r = swap_add_device_dependencies(s);
if (r < 0)
return r;
r = swap_load_devnode(s);
if (r < 0)
return r;
r = unit_patch_contexts(UNIT(s));
if (r < 0)
return r;
r = unit_add_exec_dependencies(UNIT(s), &s->exec_context);
if (r < 0)
return r;
r = unit_set_default_slice(UNIT(s));
if (r < 0)
return r;
r = swap_add_default_dependencies(s);
if (r < 0)
return r;
return 0;
}
static int swap_load(Unit *u) {
Swap *s = SWAP(u);
int r, q;
assert(s);
assert(u->load_state == UNIT_STUB);
/* Load a .swap file */
if (SWAP(u)->from_proc_swaps)
r = unit_load_fragment_and_dropin_optional(u);
else
r = unit_load_fragment_and_dropin(u);
/* Add in some extras, and do so either when we successfully loaded something or when /proc/swaps is already
* active. */
if (u->load_state == UNIT_LOADED || s->from_proc_swaps)
q = swap_add_extras(s);
else
q = 0;
if (r < 0)
return r;
if (q < 0)
return q;
return swap_verify(s);
}
static int swap_setup_unit(
Manager *m,
const char *what,
const char *what_proc_swaps,
int priority,
bool set_flags) {
_cleanup_free_ char *e = NULL;
bool delete = false;
Unit *u = NULL;
int r;
SwapParameters *p;
assert(m);
assert(what);
assert(what_proc_swaps);
r = unit_name_from_path(what, ".swap", &e);
if (r < 0)
return log_unit_error_errno(u, r, "Failed to generate unit name from path: %m");
u = manager_get_unit(m, e);
if (u &&
SWAP(u)->from_proc_swaps &&
!path_equal(SWAP(u)->parameters_proc_swaps.what, what_proc_swaps))
return log_error_errno(SYNTHETIC_ERRNO(EEXIST),
"Swap %s appeared twice with different device paths %s and %s",
e, SWAP(u)->parameters_proc_swaps.what, what_proc_swaps);
if (!u) {
delete = true;
r = unit_new_for_name(m, sizeof(Swap), e, &u);
if (r < 0)
goto fail;
SWAP(u)->what = strdup(what);
if (!SWAP(u)->what) {
r = -ENOMEM;
goto fail;
}
unit_add_to_load_queue(u);
} else
delete = false;
p = &SWAP(u)->parameters_proc_swaps;
if (!p->what) {
p->what = strdup(what_proc_swaps);
if (!p->what) {
r = -ENOMEM;
goto fail;
}
}
/* The unit is definitely around now, mark it as loaded if it was previously referenced but could not be
* loaded. After all we can load it now, from the data in /proc/swaps. */
if (IN_SET(u->load_state, UNIT_NOT_FOUND, UNIT_BAD_SETTING, UNIT_ERROR)) {
u->load_state = UNIT_LOADED;
u->load_error = 0;
}
if (set_flags) {
SWAP(u)->is_active = true;
SWAP(u)->just_activated = !SWAP(u)->from_proc_swaps;
}
SWAP(u)->from_proc_swaps = true;
p->priority = priority;
unit_add_to_dbus_queue(u);
return 0;
fail:
log_unit_warning_errno(u, r, "Failed to load swap unit: %m");
if (delete)
unit_free(u);
return r;
}
static int swap_process_new(Manager *m, const char *device, int prio, bool set_flags) {
_cleanup_(sd_device_unrefp) sd_device *d = NULL;
const char *dn, *devlink;
struct stat st, st_link;
int r;
assert(m);
r = swap_setup_unit(m, device, device, prio, set_flags);
if (r < 0)
return r;
/* If this is a block device, then let's add duplicates for
* all other names of this block device */
if (stat(device, &st) < 0 || !S_ISBLK(st.st_mode))
return 0;
r = device_new_from_stat_rdev(&d, &st);
if (r < 0) {
log_full_errno(r == -ENOENT ? LOG_DEBUG : LOG_WARNING, r,
"Failed to allocate device for swap %s: %m", device);
return 0;
}
/* Add the main device node */
if (sd_device_get_devname(d, &dn) >= 0 && !streq(dn, device))
swap_setup_unit(m, dn, device, prio, set_flags);
/* Add additional units for all symlinks */
FOREACH_DEVICE_DEVLINK(d, devlink) {
/* Don't bother with the /dev/block links */
if (streq(devlink, device))
continue;
if (path_startswith(devlink, "/dev/block/"))
continue;
if (stat(devlink, &st_link) >= 0 &&
(!S_ISBLK(st_link.st_mode) ||
st_link.st_rdev != st.st_rdev))
continue;
swap_setup_unit(m, devlink, device, prio, set_flags);
}
return 0;
}
static void swap_set_state(Swap *s, SwapState state) {
SwapState old_state;
Swap *other;
assert(s);
if (s->state != state)
bus_unit_send_pending_change_signal(UNIT(s), false);
old_state = s->state;
s->state = state;
if (!SWAP_STATE_WITH_PROCESS(state)) {
s->timer_event_source = sd_event_source_unref(s->timer_event_source);
swap_unwatch_control_pid(s);
s->control_command = NULL;
s->control_command_id = _SWAP_EXEC_COMMAND_INVALID;
}
if (state != old_state)
log_unit_debug(UNIT(s), "Changed %s -> %s", swap_state_to_string(old_state), swap_state_to_string(state));
unit_notify(UNIT(s), state_translation_table[old_state], state_translation_table[state], 0);
/* If there other units for the same device node have a job
queued it might be worth checking again if it is runnable
now. This is necessary, since swap_start() refuses
operation with EAGAIN if there's already another job for
the same device node queued. */
LIST_FOREACH_OTHERS(same_devnode, other, s)
if (UNIT(other)->job)
job_add_to_run_queue(UNIT(other)->job);
}
static int swap_coldplug(Unit *u) {
Swap *s = SWAP(u);
SwapState new_state = SWAP_DEAD;
int r;
assert(s);
assert(s->state == SWAP_DEAD);
if (s->deserialized_state != s->state)
new_state = s->deserialized_state;
else if (s->from_proc_swaps)
new_state = SWAP_ACTIVE;
if (new_state == s->state)
return 0;
if (s->control_pid > 0 &&
pid_is_unwaited(s->control_pid) &&
SWAP_STATE_WITH_PROCESS(new_state)) {
r = unit_watch_pid(UNIT(s), s->control_pid, false);
if (r < 0)
return r;
r = swap_arm_timer(s, usec_add(u->state_change_timestamp.monotonic, s->timeout_usec));
if (r < 0)
return r;
}
if (!IN_SET(new_state, SWAP_DEAD, SWAP_FAILED)) {
(void) unit_setup_dynamic_creds(u);
(void) unit_setup_exec_runtime(u);
}
swap_set_state(s, new_state);
return 0;
}
static void swap_dump(Unit *u, FILE *f, const char *prefix) {
char buf[FORMAT_TIMESPAN_MAX];
Swap *s = SWAP(u);
SwapParameters *p;
assert(s);
assert(f);
if (s->from_proc_swaps)
p = &s->parameters_proc_swaps;
else if (s->from_fragment)
p = &s->parameters_fragment;
else
p = NULL;
fprintf(f,
"%sSwap State: %s\n"
"%sResult: %s\n"
"%sWhat: %s\n"
"%sFrom /proc/swaps: %s\n"
"%sFrom fragment: %s\n",
prefix, swap_state_to_string(s->state),
prefix, swap_result_to_string(s->result),
prefix, s->what,
prefix, yes_no(s->from_proc_swaps),
prefix, yes_no(s->from_fragment));
if (s->devnode)
fprintf(f, "%sDevice Node: %s\n", prefix, s->devnode);
if (p)
fprintf(f,
"%sPriority: %i\n"
"%sOptions: %s\n",
prefix, p->priority,
prefix, strempty(p->options));
fprintf(f,
"%sTimeoutSec: %s\n",
prefix, format_timespan(buf, sizeof(buf), s->timeout_usec, USEC_PER_SEC));
if (s->control_pid > 0)
fprintf(f,
"%sControl PID: "PID_FMT"\n",
prefix, s->control_pid);
exec_context_dump(&s->exec_context, f, prefix);
kill_context_dump(&s->kill_context, f, prefix);
cgroup_context_dump(&s->cgroup_context, f, prefix);
}
static int swap_spawn(Swap *s, ExecCommand *c, pid_t *_pid) {
_cleanup_(exec_params_clear) ExecParameters exec_params = {
.flags = EXEC_APPLY_SANDBOXING|EXEC_APPLY_CHROOT|EXEC_APPLY_TTY_STDIN,
.stdin_fd = -1,
.stdout_fd = -1,
.stderr_fd = -1,
.exec_fd = -1,
};
pid_t pid;
int r;
assert(s);
assert(c);
assert(_pid);
r = unit_prepare_exec(UNIT(s));
if (r < 0)
return r;
r = swap_arm_timer(s, usec_add(now(CLOCK_MONOTONIC), s->timeout_usec));
if (r < 0)
goto fail;
r = unit_set_exec_params(UNIT(s), &exec_params);
if (r < 0)
goto fail;
r = exec_spawn(UNIT(s),
c,
&s->exec_context,
&exec_params,
s->exec_runtime,
&s->dynamic_creds,
&pid);
if (r < 0)
goto fail;
r = unit_watch_pid(UNIT(s), pid, true);
if (r < 0)
goto fail;
*_pid = pid;
return 0;
fail:
s->timer_event_source = sd_event_source_unref(s->timer_event_source);
return r;
}
static void swap_enter_dead(Swap *s, SwapResult f) {
assert(s);
if (s->result == SWAP_SUCCESS)
s->result = f;
unit_log_result(UNIT(s), s->result == SWAP_SUCCESS, swap_result_to_string(s->result));
swap_set_state(s, s->result != SWAP_SUCCESS ? SWAP_FAILED : SWAP_DEAD);
s->exec_runtime = exec_runtime_unref(s->exec_runtime, true);
exec_context_destroy_runtime_directory(&s->exec_context, UNIT(s)->manager->prefix[EXEC_DIRECTORY_RUNTIME]);
unit_unref_uid_gid(UNIT(s), true);
dynamic_creds_destroy(&s->dynamic_creds);
}
static void swap_enter_active(Swap *s, SwapResult f) {
assert(s);
if (s->result == SWAP_SUCCESS)
s->result = f;
swap_set_state(s, SWAP_ACTIVE);
}
static void swap_enter_dead_or_active(Swap *s, SwapResult f) {
assert(s);
if (s->from_proc_swaps)
swap_enter_active(s, f);
else
swap_enter_dead(s, f);
}
static void swap_enter_signal(Swap *s, SwapState state, SwapResult f) {
int r;
KillOperation kop;
assert(s);
if (s->result == SWAP_SUCCESS)
s->result = f;
if (state == SWAP_DEACTIVATING_SIGTERM)
kop = KILL_TERMINATE;
else
kop = KILL_KILL;
r = unit_kill_context(UNIT(s), &s->kill_context, kop, -1, s->control_pid, false);
if (r < 0)
goto fail;
if (r > 0) {
r = swap_arm_timer(s, usec_add(now(CLOCK_MONOTONIC), s->timeout_usec));
if (r < 0)
goto fail;
swap_set_state(s, state);
} else if (state == SWAP_DEACTIVATING_SIGTERM && s->kill_context.send_sigkill)
swap_enter_signal(s, SWAP_DEACTIVATING_SIGKILL, SWAP_SUCCESS);
else
swap_enter_dead_or_active(s, SWAP_SUCCESS);
return;
fail:
log_unit_warning_errno(UNIT(s), r, "Failed to kill processes: %m");
swap_enter_dead_or_active(s, SWAP_FAILURE_RESOURCES);
}
static void swap_enter_activating(Swap *s) {
_cleanup_free_ char *opts = NULL;
int r;
assert(s);
unit_warn_leftover_processes(UNIT(s));
s->control_command_id = SWAP_EXEC_ACTIVATE;
s->control_command = s->exec_command + SWAP_EXEC_ACTIVATE;
if (s->from_fragment) {
int priority = -1;
r = fstab_find_pri(s->parameters_fragment.options, &priority);
if (r < 0)
log_warning_errno(r, "Failed to parse swap priority \"%s\", ignoring: %m", s->parameters_fragment.options);
else if (r == 1 && s->parameters_fragment.priority >= 0)
log_warning("Duplicate swap priority configuration by Priority and Options fields.");
if (r <= 0 && s->parameters_fragment.priority >= 0) {
if (s->parameters_fragment.options)
r = asprintf(&opts, "%s,pri=%i", s->parameters_fragment.options, s->parameters_fragment.priority);
else
r = asprintf(&opts, "pri=%i", s->parameters_fragment.priority);
if (r < 0)
goto fail;
}
}
r = exec_command_set(s->control_command, "/sbin/swapon", NULL);
if (r < 0)
goto fail;
if (s->parameters_fragment.options || opts) {
r = exec_command_append(s->control_command, "-o",
opts ? : s->parameters_fragment.options, NULL);
if (r < 0)
goto fail;
}
r = exec_command_append(s->control_command, s->what, NULL);
if (r < 0)
goto fail;
swap_unwatch_control_pid(s);
r = swap_spawn(s, s->control_command, &s->control_pid);
if (r < 0)
goto fail;
swap_set_state(s, SWAP_ACTIVATING);
return;
fail:
log_unit_warning_errno(UNIT(s), r, "Failed to run 'swapon' task: %m");
swap_enter_dead_or_active(s, SWAP_FAILURE_RESOURCES);
}
static void swap_enter_deactivating(Swap *s) {
int r;
assert(s);
s->control_command_id = SWAP_EXEC_DEACTIVATE;
s->control_command = s->exec_command + SWAP_EXEC_DEACTIVATE;
r = exec_command_set(s->control_command,
"/sbin/swapoff",
s->what,
NULL);
if (r < 0)
goto fail;
swap_unwatch_control_pid(s);
r = swap_spawn(s, s->control_command, &s->control_pid);
if (r < 0)
goto fail;
swap_set_state(s, SWAP_DEACTIVATING);
return;
fail:
log_unit_warning_errno(UNIT(s), r, "Failed to run 'swapoff' task: %m");
swap_enter_dead_or_active(s, SWAP_FAILURE_RESOURCES);
}
static void swap_cycle_clear(Swap *s) {
assert(s);
s->result = SWAP_SUCCESS;
exec_command_reset_status_array(s->exec_command, _SWAP_EXEC_COMMAND_MAX);
UNIT(s)->reset_accounting = true;
}
static int swap_start(Unit *u) {
Swap *s = SWAP(u), *other;
int r;
assert(s);
/* We cannot fulfill this request right now, try again later please! */
if (IN_SET(s->state,
SWAP_DEACTIVATING,
SWAP_DEACTIVATING_SIGTERM,
SWAP_DEACTIVATING_SIGKILL))
return -EAGAIN;
/* Already on it! */
if (s->state == SWAP_ACTIVATING)
return 0;
assert(IN_SET(s->state, SWAP_DEAD, SWAP_FAILED));
if (detect_container() > 0)
return -EPERM;
/* If there's a job for another swap unit for the same node
* running, then let's not dispatch this one for now, and wait
* until that other job has finished. */
LIST_FOREACH_OTHERS(same_devnode, other, s)
if (UNIT(other)->job && UNIT(other)->job->state == JOB_RUNNING)
return -EAGAIN;
r = unit_test_start_limit(u);
if (r < 0) {
swap_enter_dead(s, SWAP_FAILURE_START_LIMIT_HIT);
return r;
}
r = unit_acquire_invocation_id(u);
if (r < 0)
return r;
swap_cycle_clear(s);
swap_enter_activating(s);
return 1;
}
static int swap_stop(Unit *u) {
Swap *s = SWAP(u);
assert(s);
switch (s->state) {
case SWAP_DEACTIVATING:
case SWAP_DEACTIVATING_SIGTERM:
case SWAP_DEACTIVATING_SIGKILL:
/* Already on it */
return 0;
case SWAP_ACTIVATING:
case SWAP_ACTIVATING_DONE:
/* There's a control process pending, directly enter kill mode */
swap_enter_signal(s, SWAP_DEACTIVATING_SIGTERM, SWAP_SUCCESS);
return 0;
case SWAP_ACTIVE:
if (detect_container() > 0)
return -EPERM;
swap_enter_deactivating(s);
return 1;
default:
assert_not_reached("Unexpected state.");
}
}
static int swap_serialize(Unit *u, FILE *f, FDSet *fds) {
Swap *s = SWAP(u);
assert(s);
assert(f);
assert(fds);
(void) serialize_item(f, "state", swap_state_to_string(s->state));
(void) serialize_item(f, "result", swap_result_to_string(s->result));
if (s->control_pid > 0)
(void) serialize_item_format(f, "control-pid", PID_FMT, s->control_pid);
if (s->control_command_id >= 0)
(void) serialize_item(f, "control-command", swap_exec_command_to_string(s->control_command_id));
return 0;
}
static int swap_deserialize_item(Unit *u, const char *key, const char *value, FDSet *fds) {
Swap *s = SWAP(u);
assert(s);
assert(fds);
if (streq(key, "state")) {
SwapState state;
state = swap_state_from_string(value);
if (state < 0)
log_unit_debug(u, "Failed to parse state value: %s", value);
else
s->deserialized_state = state;
} else if (streq(key, "result")) {
SwapResult f;
f = swap_result_from_string(value);
if (f < 0)
log_unit_debug(u, "Failed to parse result value: %s", value);
else if (f != SWAP_SUCCESS)
s->result = f;
} else if (streq(key, "control-pid")) {
pid_t pid;
if (parse_pid(value, &pid) < 0)
log_unit_debug(u, "Failed to parse control-pid value: %s", value);
else
s->control_pid = pid;
} else if (streq(key, "control-command")) {
SwapExecCommand id;
id = swap_exec_command_from_string(value);
if (id < 0)
log_unit_debug(u, "Failed to parse exec-command value: %s", value);
else {
s->control_command_id = id;
s->control_command = s->exec_command + id;
}
} else
log_unit_debug(u, "Unknown serialization key: %s", key);
return 0;
}
_pure_ static UnitActiveState swap_active_state(Unit *u) {
assert(u);
return state_translation_table[SWAP(u)->state];
}
_pure_ static const char *swap_sub_state_to_string(Unit *u) {
assert(u);
return swap_state_to_string(SWAP(u)->state);
}
_pure_ static bool swap_may_gc(Unit *u) {
Swap *s = SWAP(u);
assert(s);
if (s->from_proc_swaps)
return false;
return true;
}
static void swap_sigchld_event(Unit *u, pid_t pid, int code, int status) {
Swap *s = SWAP(u);
SwapResult f;
assert(s);
assert(pid >= 0);
if (pid != s->control_pid)
return;
s->control_pid = 0;
if (is_clean_exit(code, status, EXIT_CLEAN_COMMAND, NULL))
f = SWAP_SUCCESS;
else if (code == CLD_EXITED)
f = SWAP_FAILURE_EXIT_CODE;
else if (code == CLD_KILLED)
f = SWAP_FAILURE_SIGNAL;
else if (code == CLD_DUMPED)
f = SWAP_FAILURE_CORE_DUMP;
else
assert_not_reached("Unknown code");
if (s->result == SWAP_SUCCESS)
s->result = f;
if (s->control_command) {
exec_status_exit(&s->control_command->exec_status, &s->exec_context, pid, code, status);
s->control_command = NULL;
s->control_command_id = _SWAP_EXEC_COMMAND_INVALID;
}
unit_log_process_exit(
u, f == SWAP_SUCCESS ? LOG_DEBUG : LOG_NOTICE,
"Swap process",
swap_exec_command_to_string(s->control_command_id),
code, status);
switch (s->state) {
case SWAP_ACTIVATING:
case SWAP_ACTIVATING_DONE:
if (f == SWAP_SUCCESS || s->from_proc_swaps)
swap_enter_active(s, f);
else
swap_enter_dead(s, f);
break;
case SWAP_DEACTIVATING:
case SWAP_DEACTIVATING_SIGKILL:
case SWAP_DEACTIVATING_SIGTERM:
swap_enter_dead_or_active(s, f);
break;
default:
assert_not_reached("Uh, control process died at wrong time.");
}
/* Notify clients about changed exit status */
unit_add_to_dbus_queue(u);
}
static int swap_dispatch_timer(sd_event_source *source, usec_t usec, void *userdata) {
Swap *s = SWAP(userdata);
assert(s);
assert(s->timer_event_source == source);
switch (s->state) {
case SWAP_ACTIVATING:
case SWAP_ACTIVATING_DONE:
log_unit_warning(UNIT(s), "Activation timed out. Stopping.");
swap_enter_signal(s, SWAP_DEACTIVATING_SIGTERM, SWAP_FAILURE_TIMEOUT);
break;
case SWAP_DEACTIVATING:
log_unit_warning(UNIT(s), "Deactivation timed out. Stopping.");
swap_enter_signal(s, SWAP_DEACTIVATING_SIGTERM, SWAP_FAILURE_TIMEOUT);
break;
case SWAP_DEACTIVATING_SIGTERM:
if (s->kill_context.send_sigkill) {
log_unit_warning(UNIT(s), "Swap process timed out. Killing.");
swap_enter_signal(s, SWAP_DEACTIVATING_SIGKILL, SWAP_FAILURE_TIMEOUT);
} else {
log_unit_warning(UNIT(s), "Swap process timed out. Skipping SIGKILL. Ignoring.");
swap_enter_dead_or_active(s, SWAP_FAILURE_TIMEOUT);
}
break;
case SWAP_DEACTIVATING_SIGKILL:
log_unit_warning(UNIT(s), "Swap process still around after SIGKILL. Ignoring.");
swap_enter_dead_or_active(s, SWAP_FAILURE_TIMEOUT);
break;
default:
assert_not_reached("Timeout at wrong time.");
}
return 0;
}
static int swap_load_proc_swaps(Manager *m, bool set_flags) {
unsigned i;
assert(m);
rewind(m->proc_swaps);
(void) fscanf(m->proc_swaps, "%*s %*s %*s %*s %*s\n");
for (i = 1;; i++) {
_cleanup_free_ char *dev = NULL, *d = NULL;
int prio = 0, k;
k = fscanf(m->proc_swaps,
"%ms " /* device/file */
"%*s " /* type of swap */
"%*s " /* swap size */
"%*s " /* used */
"%i\n", /* priority */
&dev, &prio);
if (k != 2) {
if (k == EOF)
break;
log_warning("Failed to parse /proc/swaps:%u.", i);
continue;
}
if (cunescape(dev, UNESCAPE_RELAX, &d) < 0)
return log_oom();
device_found_node(m, d, DEVICE_FOUND_SWAP, DEVICE_FOUND_SWAP);
(void) swap_process_new(m, d, prio, set_flags);
}
return 0;
}
static int swap_dispatch_io(sd_event_source *source, int fd, uint32_t revents, void *userdata) {
Manager *m = userdata;
Unit *u;
int r;
assert(m);
assert(revents & EPOLLPRI);
r = swap_load_proc_swaps(m, true);
if (r < 0) {
log_error_errno(r, "Failed to reread /proc/swaps: %m");
/* Reset flags, just in case, for late calls */
LIST_FOREACH(units_by_type, u, m->units_by_type[UNIT_SWAP]) {
Swap *swap = SWAP(u);
swap->is_active = swap->just_activated = false;
}
return 0;
}
manager_dispatch_load_queue(m);
LIST_FOREACH(units_by_type, u, m->units_by_type[UNIT_SWAP]) {
Swap *swap = SWAP(u);
if (!swap->is_active) {
swap_unset_proc_swaps(swap);
switch (swap->state) {
case SWAP_ACTIVE:
/* This has just been deactivated */
swap_enter_dead(swap, SWAP_SUCCESS);
break;
default:
/* Fire again */
swap_set_state(swap, swap->state);
break;
}
if (swap->what)
device_found_node(m, swap->what, 0, DEVICE_FOUND_SWAP);
} else if (swap->just_activated) {
/* New swap entry */
switch (swap->state) {
case SWAP_DEAD:
case SWAP_FAILED:
(void) unit_acquire_invocation_id(u);
swap_cycle_clear(swap);
swap_enter_active(swap, SWAP_SUCCESS);
break;
case SWAP_ACTIVATING:
swap_set_state(swap, SWAP_ACTIVATING_DONE);
break;
default:
/* Nothing really changed, but let's
* issue an notification call
* nonetheless, in case somebody is
* waiting for this. */
swap_set_state(swap, swap->state);
break;
}
}
/* Reset the flags for later calls */
swap->is_active = swap->just_activated = false;
}
return 1;
}
static Unit *swap_following(Unit *u) {
Swap *s = SWAP(u);
Swap *other, *first = NULL;
assert(s);
/* If the user configured the swap through /etc/fstab or
* a device unit, follow that. */
if (s->from_fragment)
return NULL;
LIST_FOREACH_OTHERS(same_devnode, other, s)
if (other->from_fragment)
return UNIT(other);
/* Otherwise, make everybody follow the unit that's named after
* the swap device in the kernel */
if (streq_ptr(s->what, s->devnode))
return NULL;
LIST_FOREACH_AFTER(same_devnode, other, s)
if (streq_ptr(other->what, other->devnode))
return UNIT(other);
LIST_FOREACH_BEFORE(same_devnode, other, s) {
if (streq_ptr(other->what, other->devnode))
return UNIT(other);
first = other;
}
/* Fall back to the first on the list */
return UNIT(first);
}
static int swap_following_set(Unit *u, Set **_set) {
Swap *s = SWAP(u), *other;
_cleanup_set_free_ Set *set = NULL;
int r;
assert(s);
assert(_set);
if (LIST_JUST_US(same_devnode, s)) {
*_set = NULL;
return 0;
}
set = set_new(NULL);
if (!set)
return -ENOMEM;
LIST_FOREACH_OTHERS(same_devnode, other, s) {
r = set_put(set, other);
if (r < 0)
return r;
}
*_set = TAKE_PTR(set);
return 1;
}
static void swap_shutdown(Manager *m) {
assert(m);
m->swap_event_source = sd_event_source_unref(m->swap_event_source);
m->proc_swaps = safe_fclose(m->proc_swaps);
m->swaps_by_devnode = hashmap_free(m->swaps_by_devnode);
}
static void swap_enumerate(Manager *m) {
int r;
assert(m);
if (!m->proc_swaps) {
m->proc_swaps = fopen("/proc/swaps", "re");
if (!m->proc_swaps) {
if (errno == ENOENT)
log_debug_errno(errno, "Not swap enabled, skipping enumeration.");
else
log_warning_errno(errno, "Failed to open /proc/swaps, ignoring: %m");
return;
}
r = sd_event_add_io(m->event, &m->swap_event_source, fileno(m->proc_swaps), EPOLLPRI, swap_dispatch_io, m);
if (r < 0) {
log_error_errno(r, "Failed to watch /proc/swaps: %m");
goto fail;
}
/* Dispatch this before we dispatch SIGCHLD, so that
* we always get the events from /proc/swaps before
* the SIGCHLD of /sbin/swapon. */
r = sd_event_source_set_priority(m->swap_event_source, SD_EVENT_PRIORITY_NORMAL-10);
if (r < 0) {
log_error_errno(r, "Failed to change /proc/swaps priority: %m");
goto fail;
}
(void) sd_event_source_set_description(m->swap_event_source, "swap-proc");
}
r = swap_load_proc_swaps(m, false);
if (r < 0)
goto fail;
return;
fail:
swap_shutdown(m);
}
int swap_process_device_new(Manager *m, sd_device *dev) {
_cleanup_free_ char *e = NULL;
const char *dn, *devlink;
Unit *u;
int r = 0;
assert(m);
assert(dev);
r = sd_device_get_devname(dev, &dn);
if (r < 0)
return 0;
r = unit_name_from_path(dn, ".swap", &e);
if (r < 0)
return r;
u = manager_get_unit(m, e);
if (u)
r = swap_set_devnode(SWAP(u), dn);
FOREACH_DEVICE_DEVLINK(dev, devlink) {
_cleanup_free_ char *n = NULL;
int q;
q = unit_name_from_path(devlink, ".swap", &n);
if (q < 0)
return q;
u = manager_get_unit(m, n);
if (u) {
q = swap_set_devnode(SWAP(u), dn);
if (q < 0)
r = q;
}
}
return r;
}
int swap_process_device_remove(Manager *m, sd_device *dev) {
const char *dn;
int r = 0;
Swap *s;
r = sd_device_get_devname(dev, &dn);
if (r < 0)
return 0;
while ((s = hashmap_get(m->swaps_by_devnode, dn))) {
int q;
q = swap_set_devnode(s, NULL);
if (q < 0)
r = q;
}
return r;
}
static void swap_reset_failed(Unit *u) {
Swap *s = SWAP(u);
assert(s);
if (s->state == SWAP_FAILED)
swap_set_state(s, SWAP_DEAD);
s->result = SWAP_SUCCESS;
}
static int swap_kill(Unit *u, KillWho who, int signo, sd_bus_error *error) {
return unit_kill_common(u, who, signo, -1, SWAP(u)->control_pid, error);
}
static int swap_get_timeout(Unit *u, usec_t *timeout) {
Swap *s = SWAP(u);
usec_t t;
int r;
if (!s->timer_event_source)
return 0;
r = sd_event_source_get_time(s->timer_event_source, &t);
if (r < 0)
return r;
if (t == USEC_INFINITY)
return 0;
*timeout = t;
return 1;
}
static bool swap_supported(void) {
static int supported = -1;
/* If swap support is not available in the kernel, or we are
* running in a container we don't support swap units, and any
* attempts to starting one should fail immediately. */
if (supported < 0)
supported =
access("/proc/swaps", F_OK) >= 0 &&
detect_container() <= 0;
return supported;
}
static int swap_control_pid(Unit *u) {
Swap *s = SWAP(u);
assert(s);
return s->control_pid;
}
static const char* const swap_exec_command_table[_SWAP_EXEC_COMMAND_MAX] = {
[SWAP_EXEC_ACTIVATE] = "ExecActivate",
[SWAP_EXEC_DEACTIVATE] = "ExecDeactivate",
};
DEFINE_STRING_TABLE_LOOKUP(swap_exec_command, SwapExecCommand);
static const char* const swap_result_table[_SWAP_RESULT_MAX] = {
[SWAP_SUCCESS] = "success",
[SWAP_FAILURE_RESOURCES] = "resources",
[SWAP_FAILURE_TIMEOUT] = "timeout",
[SWAP_FAILURE_EXIT_CODE] = "exit-code",
[SWAP_FAILURE_SIGNAL] = "signal",
[SWAP_FAILURE_CORE_DUMP] = "core-dump",
[SWAP_FAILURE_START_LIMIT_HIT] = "start-limit-hit",
};
DEFINE_STRING_TABLE_LOOKUP(swap_result, SwapResult);
const UnitVTable swap_vtable = {
.object_size = sizeof(Swap),
.exec_context_offset = offsetof(Swap, exec_context),
.cgroup_context_offset = offsetof(Swap, cgroup_context),
.kill_context_offset = offsetof(Swap, kill_context),
.exec_runtime_offset = offsetof(Swap, exec_runtime),
.dynamic_creds_offset = offsetof(Swap, dynamic_creds),
.sections =
"Unit\0"
"Swap\0"
"Install\0",
.private_section = "Swap",
.init = swap_init,
.load = swap_load,
.done = swap_done,
.coldplug = swap_coldplug,
.dump = swap_dump,
.start = swap_start,
.stop = swap_stop,
.kill = swap_kill,
.get_timeout = swap_get_timeout,
.serialize = swap_serialize,
.deserialize_item = swap_deserialize_item,
.active_state = swap_active_state,
.sub_state_to_string = swap_sub_state_to_string,
.may_gc = swap_may_gc,
.sigchld_event = swap_sigchld_event,
.reset_failed = swap_reset_failed,
.control_pid = swap_control_pid,
.bus_vtable = bus_swap_vtable,
.bus_set_property = bus_swap_set_property,
.bus_commit_properties = bus_swap_commit_properties,
.following = swap_following,
.following_set = swap_following_set,
.enumerate = swap_enumerate,
.shutdown = swap_shutdown,
.supported = swap_supported,
.status_message_formats = {
.starting_stopping = {
[0] = "Activating swap %s...",
[1] = "Deactivating swap %s...",
},
.finished_start_job = {
[JOB_DONE] = "Activated swap %s.",
[JOB_FAILED] = "Failed to activate swap %s.",
[JOB_TIMEOUT] = "Timed out activating swap %s.",
},
.finished_stop_job = {
[JOB_DONE] = "Deactivated swap %s.",
[JOB_FAILED] = "Failed deactivating swap %s.",
[JOB_TIMEOUT] = "Timed out deactivating swap %s.",
},
},
};
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