Adding upstream version 255.4.upstream/255.4

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1352 insertions, 0 deletions

diff --git a/src/udev/udev-manager.c b/src/udev/udev-manager.c
new file mode 100644
index 0000000..8077e51
--- /dev/null
+++ b/src/udev/udev-manager.c
@@ -0,0 +1,1352 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+
+#include "blockdev-util.h"
+#include "cgroup-util.h"
+#include "common-signal.h"
+#include "cpu-set-util.h"
+#include "daemon-util.h"
+#include "device-monitor-private.h"
+#include "device-private.h"
+#include "device-util.h"
+#include "errno-list.h"
+#include "event-util.h"
+#include "fd-util.h"
+#include "fs-util.h"
+#include "hashmap.h"
+#include "inotify-util.h"
+#include "iovec-util.h"
+#include "limits-util.h"
+#include "list.h"
+#include "mkdir.h"
+#include "process-util.h"
+#include "selinux-util.h"
+#include "signal-util.h"
+#include "socket-util.h"
+#include "string-util.h"
+#include "syslog-util.h"
+#include "udev-builtin.h"
+#include "udev-ctrl.h"
+#include "udev-event.h"
+#include "udev-manager.h"
+#include "udev-node.h"
+#include "udev-spawn.h"
+#include "udev-trace.h"
+#include "udev-util.h"
+#include "udev-watch.h"
+#include "udev-worker.h"
+
+#define WORKER_NUM_MAX UINT64_C(2048)
+
+#define EVENT_RETRY_INTERVAL_USEC (200 * USEC_PER_MSEC)
+#define EVENT_RETRY_TIMEOUT_USEC  (3 * USEC_PER_MINUTE)
+
+typedef enum EventState {
+        EVENT_UNDEF,
+        EVENT_QUEUED,
+        EVENT_RUNNING,
+} EventState;
+
+typedef struct Event {
+        Manager *manager;
+        Worker *worker;
+        EventState state;
+
+        sd_device *dev;
+
+        sd_device_action_t action;
+        uint64_t seqnum;
+        uint64_t blocker_seqnum;
+        const char *id;
+        const char *devpath;
+        const char *devpath_old;
+        const char *devnode;
+
+        /* Used when the device is locked by another program. */
+        usec_t retry_again_next_usec;
+        usec_t retry_again_timeout_usec;
+        sd_event_source *retry_event_source;
+
+        sd_event_source *timeout_warning_event;
+        sd_event_source *timeout_event;
+
+        LIST_FIELDS(Event, event);
+} Event;
+
+typedef enum WorkerState {
+        WORKER_UNDEF,
+        WORKER_RUNNING,
+        WORKER_IDLE,
+        WORKER_KILLED,
+        WORKER_KILLING,
+} WorkerState;
+
+typedef struct Worker {
+        Manager *manager;
+        pid_t pid;
+        sd_event_source *child_event_source;
+        sd_device_monitor *monitor;
+        WorkerState state;
+        Event *event;
+} Worker;
+
+static Event *event_free(Event *event) {
+        if (!event)
+                return NULL;
+
+        assert(event->manager);
+
+        LIST_REMOVE(event, event->manager->events, event);
+        sd_device_unref(event->dev);
+
+        sd_event_source_unref(event->retry_event_source);
+        sd_event_source_unref(event->timeout_warning_event);
+        sd_event_source_unref(event->timeout_event);
+
+        if (event->worker)
+                event->worker->event = NULL;
+
+        return mfree(event);
+}
+
+static void event_queue_cleanup(Manager *manager, EventState match_state) {
+        LIST_FOREACH(event, event, manager->events) {
+                if (match_state != EVENT_UNDEF && match_state != event->state)
+                        continue;
+
+                event_free(event);
+        }
+}
+
+static Worker *worker_free(Worker *worker) {
+        if (!worker)
+                return NULL;
+
+        if (worker->manager)
+                hashmap_remove(worker->manager->workers, PID_TO_PTR(worker->pid));
+
+        sd_event_source_unref(worker->child_event_source);
+        sd_device_monitor_unref(worker->monitor);
+        event_free(worker->event);
+
+        return mfree(worker);
+}
+
+DEFINE_TRIVIAL_CLEANUP_FUNC(Worker*, worker_free);
+DEFINE_PRIVATE_HASH_OPS_WITH_VALUE_DESTRUCTOR(worker_hash_op, void, trivial_hash_func, trivial_compare_func, Worker, worker_free);
+
+Manager* manager_free(Manager *manager) {
+        if (!manager)
+                return NULL;
+
+        udev_builtin_exit();
+
+        hashmap_free_free_free(manager->properties);
+        udev_rules_free(manager->rules);
+
+        hashmap_free(manager->workers);
+        event_queue_cleanup(manager, EVENT_UNDEF);
+
+        safe_close(manager->inotify_fd);
+        safe_close_pair(manager->worker_watch);
+
+        sd_device_monitor_unref(manager->monitor);
+        udev_ctrl_unref(manager->ctrl);
+
+        sd_event_source_unref(manager->inotify_event);
+        sd_event_source_unref(manager->kill_workers_event);
+        sd_event_source_unref(manager->memory_pressure_event_source);
+        sd_event_source_unref(manager->sigrtmin18_event_source);
+        sd_event_unref(manager->event);
+
+        free(manager->cgroup);
+        return mfree(manager);
+}
+
+static int on_sigchld(sd_event_source *s, const siginfo_t *si, void *userdata);
+
+static int worker_new(Worker **ret, Manager *manager, sd_device_monitor *worker_monitor, pid_t pid) {
+        _cleanup_(worker_freep) Worker *worker = NULL;
+        int r;
+
+        assert(ret);
+        assert(manager);
+        assert(worker_monitor);
+        assert(pid > 1);
+
+        /* close monitor, but keep address around */
+        device_monitor_disconnect(worker_monitor);
+
+        worker = new(Worker, 1);
+        if (!worker)
+                return -ENOMEM;
+
+        *worker = (Worker) {
+                .monitor = sd_device_monitor_ref(worker_monitor),
+                .pid = pid,
+        };
+
+        r = sd_event_add_child(manager->event, &worker->child_event_source, pid, WEXITED, on_sigchld, worker);
+        if (r < 0)
+                return r;
+
+        r = hashmap_ensure_put(&manager->workers, &worker_hash_op, PID_TO_PTR(pid), worker);
+        if (r < 0)
+                return r;
+
+        worker->manager = manager;
+
+        *ret = TAKE_PTR(worker);
+        return 0;
+}
+
+static void manager_kill_workers(Manager *manager, bool force) {
+        Worker *worker;
+
+        assert(manager);
+
+        HASHMAP_FOREACH(worker, manager->workers) {
+                if (worker->state == WORKER_KILLED)
+                        continue;
+
+                if (worker->state == WORKER_RUNNING && !force) {
+                        worker->state = WORKER_KILLING;
+                        continue;
+                }
+
+                worker->state = WORKER_KILLED;
+                (void) kill(worker->pid, SIGTERM);
+        }
+}
+
+static void manager_exit(Manager *manager) {
+        assert(manager);
+
+        manager->exit = true;
+
+        (void) sd_notify(/* unset= */ false, NOTIFY_STOPPING);
+
+        /* close sources of new events and discard buffered events */
+        manager->ctrl = udev_ctrl_unref(manager->ctrl);
+
+        manager->inotify_event = sd_event_source_disable_unref(manager->inotify_event);
+        manager->inotify_fd = safe_close(manager->inotify_fd);
+
+        manager->monitor = sd_device_monitor_unref(manager->monitor);
+
+        /* discard queued events and kill workers */
+        event_queue_cleanup(manager, EVENT_QUEUED);
+        manager_kill_workers(manager, true);
+}
+
+static void notify_ready(Manager *manager) {
+        int r;
+
+        assert(manager);
+
+        r = sd_notifyf(/* unset= */ false,
+                       "READY=1\n"
+                       "STATUS=Processing with %u children at max", manager->children_max);
+        if (r < 0)
+                log_warning_errno(r, "Failed to send readiness notification, ignoring: %m");
+}
+
+/* reload requested, HUP signal received, rules changed, builtin changed */
+static void manager_reload(Manager *manager, bool force) {
+        _cleanup_(udev_rules_freep) UdevRules *rules = NULL;
+        usec_t now_usec;
+        int r;
+
+        assert(manager);
+
+        assert_se(sd_event_now(manager->event, CLOCK_MONOTONIC, &now_usec) >= 0);
+        if (!force && now_usec < usec_add(manager->last_usec, 3 * USEC_PER_SEC))
+                /* check for changed config, every 3 seconds at most */
+                return;
+        manager->last_usec = now_usec;
+
+        /* Reload SELinux label database, to make the child inherit the up-to-date database. */
+        mac_selinux_maybe_reload();
+
+        /* Nothing changed. It is not necessary to reload. */
+        if (!udev_rules_should_reload(manager->rules) && !udev_builtin_should_reload()) {
+
+                if (!force)
+                        return;
+
+                /* If we eat this up, then tell our service manager to just continue */
+                (void) sd_notifyf(/* unset= */ false,
+                                  "RELOADING=1\n"
+                                  "STATUS=Skipping configuration reloading, nothing changed.\n"
+                                  "MONOTONIC_USEC=" USEC_FMT, now(CLOCK_MONOTONIC));
+        } else {
+                (void) sd_notifyf(/* unset= */ false,
+                                  "RELOADING=1\n"
+                                  "STATUS=Flushing configuration...\n"
+                                  "MONOTONIC_USEC=" USEC_FMT, now(CLOCK_MONOTONIC));
+
+                manager_kill_workers(manager, false);
+
+                udev_builtin_exit();
+                udev_builtin_init();
+
+                r = udev_rules_load(&rules, manager->resolve_name_timing);
+                if (r < 0)
+                        log_warning_errno(r, "Failed to read udev rules, using the previously loaded rules, ignoring: %m");
+                else
+                        udev_rules_free_and_replace(manager->rules, rules);
+        }
+
+        notify_ready(manager);
+}
+
+static int on_kill_workers_event(sd_event_source *s, uint64_t usec, void *userdata) {
+        Manager *manager = ASSERT_PTR(userdata);
+
+        log_debug("Cleanup idle workers");
+        manager_kill_workers(manager, false);
+
+        return 1;
+}
+
+static int on_event_timeout(sd_event_source *s, uint64_t usec, void *userdata) {
+        Event *event = ASSERT_PTR(userdata);
+
+        assert(event->manager);
+        assert(event->worker);
+
+        kill_and_sigcont(event->worker->pid, event->manager->timeout_signal);
+        event->worker->state = WORKER_KILLED;
+
+        log_device_error(event->dev, "Worker ["PID_FMT"] processing SEQNUM=%"PRIu64" killed", event->worker->pid, event->seqnum);
+
+        return 1;
+}
+
+static int on_event_timeout_warning(sd_event_source *s, uint64_t usec, void *userdata) {
+        Event *event = ASSERT_PTR(userdata);
+
+        assert(event->worker);
+
+        log_device_warning(event->dev, "Worker ["PID_FMT"] processing SEQNUM=%"PRIu64" is taking a long time", event->worker->pid, event->seqnum);
+
+        return 1;
+}
+
+static void worker_attach_event(Worker *worker, Event *event) {
+        Manager *manager;
+        sd_event *e;
+
+        assert(worker);
+        assert(worker->manager);
+        assert(event);
+        assert(!event->worker);
+        assert(!worker->event);
+
+        worker->state = WORKER_RUNNING;
+        worker->event = event;
+        event->state = EVENT_RUNNING;
+        event->worker = worker;
+
+        manager = worker->manager;
+        e = manager->event;
+
+        (void) sd_event_add_time_relative(e, &event->timeout_warning_event, CLOCK_MONOTONIC,
+                                          udev_warn_timeout(manager->timeout_usec), USEC_PER_SEC,
+                                          on_event_timeout_warning, event);
+
+        (void) sd_event_add_time_relative(e, &event->timeout_event, CLOCK_MONOTONIC,
+                                          manager->timeout_usec, USEC_PER_SEC,
+                                          on_event_timeout, event);
+}
+
+static int worker_spawn(Manager *manager, Event *event) {
+        _cleanup_(sd_device_monitor_unrefp) sd_device_monitor *worker_monitor = NULL;
+        Worker *worker;
+        pid_t pid;
+        int r;
+
+        /* listen for new events */
+        r = device_monitor_new_full(&worker_monitor, MONITOR_GROUP_NONE, -1);
+        if (r < 0)
+                return r;
+
+        (void) sd_device_monitor_set_description(worker_monitor, "worker");
+
+        /* allow the main daemon netlink address to send devices to the worker */
+        r = device_monitor_allow_unicast_sender(worker_monitor, manager->monitor);
+        if (r < 0)
+                return log_error_errno(r, "Worker: Failed to set unicast sender: %m");
+
+        r = device_monitor_enable_receiving(worker_monitor);
+        if (r < 0)
+                return log_error_errno(r, "Worker: Failed to enable receiving of device: %m");
+
+        r = safe_fork("(udev-worker)", FORK_DEATHSIG_SIGTERM, &pid);
+        if (r < 0) {
+                event->state = EVENT_QUEUED;
+                return log_error_errno(r, "Failed to fork() worker: %m");
+        }
+        if (r == 0) {
+                _cleanup_(udev_worker_done) UdevWorker w = {
+                        .monitor = TAKE_PTR(worker_monitor),
+                        .properties = TAKE_PTR(manager->properties),
+                        .rules = TAKE_PTR(manager->rules),
+                        .pipe_fd = TAKE_FD(manager->worker_watch[WRITE_END]),
+                        .inotify_fd = TAKE_FD(manager->inotify_fd),
+                        .exec_delay_usec = manager->exec_delay_usec,
+                        .timeout_usec = manager->timeout_usec,
+                        .timeout_signal = manager->timeout_signal,
+                        .log_level = manager->log_level,
+                        .blockdev_read_only = manager->blockdev_read_only,
+                };
+
+                /* Worker process */
+                r = udev_worker_main(&w, event->dev);
+                log_close();
+                _exit(r < 0 ? EXIT_FAILURE : EXIT_SUCCESS);
+        }
+
+        r = worker_new(&worker, manager, worker_monitor, pid);
+        if (r < 0)
+                return log_error_errno(r, "Failed to create worker object: %m");
+
+        worker_attach_event(worker, event);
+
+        log_device_debug(event->dev, "Worker ["PID_FMT"] is forked for processing SEQNUM=%"PRIu64".", pid, event->seqnum);
+        return 0;
+}
+
+static int event_run(Event *event) {
+        static bool log_children_max_reached = true;
+        Manager *manager;
+        Worker *worker;
+        int r;
+
+        assert(event);
+        assert(event->manager);
+
+        log_device_uevent(event->dev, "Device ready for processing");
+
+        (void) event_source_disable(event->retry_event_source);
+
+        manager = event->manager;
+        HASHMAP_FOREACH(worker, manager->workers) {
+                if (worker->state != WORKER_IDLE)
+                        continue;
+
+                r = device_monitor_send_device(manager->monitor, worker->monitor, event->dev);
+                if (r < 0) {
+                        log_device_error_errno(event->dev, r, "Worker ["PID_FMT"] did not accept message, killing the worker: %m",
+                                               worker->pid);
+                        (void) kill(worker->pid, SIGKILL);
+                        worker->state = WORKER_KILLED;
+                        continue;
+                }
+                worker_attach_event(worker, event);
+                return 1; /* event is now processing. */
+        }
+
+        if (hashmap_size(manager->workers) >= manager->children_max) {
+                /* Avoid spamming the debug logs if the limit is already reached and
+                 * many events still need to be processed */
+                if (log_children_max_reached && manager->children_max > 1) {
+                        log_debug("Maximum number (%u) of children reached.", hashmap_size(manager->workers));
+                        log_children_max_reached = false;
+                }
+                return 0; /* no free worker */
+        }
+
+        /* Re-enable the debug message for the next batch of events */
+        log_children_max_reached = true;
+
+        /* start new worker and pass initial device */
+        r = worker_spawn(manager, event);
+        if (r < 0)
+                return r;
+
+        return 1; /* event is now processing. */
+}
+
+bool devpath_conflict(const char *a, const char *b) {
+        /* This returns true when two paths are equivalent, or one is a child of another. */
+
+        if (!a || !b)
+                return false;
+
+        for (; *a != '\0' && *b != '\0'; a++, b++)
+                if (*a != *b)
+                        return false;
+
+        return *a == '/' || *b == '/' || *a == *b;
+}
+
+static int event_is_blocked(Event *event) {
+        Event *loop_event = NULL;
+        int r;
+
+        /* lookup event for identical, parent, child device */
+
+        assert(event);
+        assert(event->manager);
+        assert(event->blocker_seqnum <= event->seqnum);
+
+        if (event->retry_again_next_usec > 0) {
+                usec_t now_usec;
+
+                r = sd_event_now(event->manager->event, CLOCK_BOOTTIME, &now_usec);
+                if (r < 0)
+                        return r;
+
+                if (event->retry_again_next_usec > now_usec)
+                        return true;
+        }
+
+        if (event->blocker_seqnum == event->seqnum)
+                /* we have checked previously and no blocker found */
+                return false;
+
+        LIST_FOREACH(event, e, event->manager->events) {
+                loop_event = e;
+
+                /* we already found a later event, earlier cannot block us, no need to check again */
+                if (loop_event->seqnum < event->blocker_seqnum)
+                        continue;
+
+                /* event we checked earlier still exists, no need to check again */
+                if (loop_event->seqnum == event->blocker_seqnum)
+                        return true;
+
+                /* found ourself, no later event can block us */
+                if (loop_event->seqnum >= event->seqnum)
+                        goto no_blocker;
+
+                /* found event we have not checked */
+                break;
+        }
+
+        assert(loop_event);
+        assert(loop_event->seqnum > event->blocker_seqnum &&
+               loop_event->seqnum < event->seqnum);
+
+        /* check if queue contains events we depend on */
+        LIST_FOREACH(event, e, loop_event) {
+                loop_event = e;
+
+                /* found ourself, no later event can block us */
+                if (loop_event->seqnum >= event->seqnum)
+                        goto no_blocker;
+
+                if (streq_ptr(loop_event->id, event->id))
+                        break;
+
+                if (devpath_conflict(event->devpath, loop_event->devpath) ||
+                    devpath_conflict(event->devpath, loop_event->devpath_old) ||
+                    devpath_conflict(event->devpath_old, loop_event->devpath))
+                        break;
+
+                if (event->devnode && streq_ptr(event->devnode, loop_event->devnode))
+                        break;
+        }
+
+        assert(loop_event);
+
+        log_device_debug(event->dev, "SEQNUM=%" PRIu64 " blocked by SEQNUM=%" PRIu64,
+                         event->seqnum, loop_event->seqnum);
+
+        event->blocker_seqnum = loop_event->seqnum;
+        return true;
+
+no_blocker:
+        event->blocker_seqnum = event->seqnum;
+        return false;
+}
+
+static int event_queue_start(Manager *manager) {
+        int r;
+
+        assert(manager);
+
+        if (!manager->events || manager->exit || manager->stop_exec_queue)
+                return 0;
+
+        /* To make the stack directory /run/udev/links cleaned up later. */
+        manager->udev_node_needs_cleanup = true;
+
+        r = event_source_disable(manager->kill_workers_event);
+        if (r < 0)
+                log_warning_errno(r, "Failed to disable event source for cleaning up idle workers, ignoring: %m");
+
+        manager_reload(manager, /* force = */ false);
+
+        LIST_FOREACH(event, event, manager->events) {
+                if (event->state != EVENT_QUEUED)
+                        continue;
+
+                /* do not start event if parent or child event is still running or queued */
+                r = event_is_blocked(event);
+                if (r > 0)
+                        continue;
+                if (r < 0)
+                        log_device_warning_errno(event->dev, r,
+                                                 "Failed to check dependencies for event (SEQNUM=%"PRIu64", ACTION=%s), "
+                                                 "assuming there is no blocking event, ignoring: %m",
+                                                 event->seqnum,
+                                                 strna(device_action_to_string(event->action)));
+
+                r = event_run(event);
+                if (r <= 0) /* 0 means there are no idle workers. Let's escape from the loop. */
+                        return r;
+        }
+
+        return 0;
+}
+
+static int on_event_retry(sd_event_source *s, uint64_t usec, void *userdata) {
+        /* This does nothing. The on_post() callback will start the event if there exists an idle worker. */
+        return 1;
+}
+
+static int event_requeue(Event *event) {
+        usec_t now_usec;
+        int r;
+
+        assert(event);
+        assert(event->manager);
+        assert(event->manager->event);
+
+        event->timeout_warning_event = sd_event_source_disable_unref(event->timeout_warning_event);
+        event->timeout_event = sd_event_source_disable_unref(event->timeout_event);
+
+        /* add a short delay to suppress busy loop */
+        r = sd_event_now(event->manager->event, CLOCK_BOOTTIME, &now_usec);
+        if (r < 0)
+                return log_device_warning_errno(event->dev, r,
+                                                "Failed to get current time, "
+                                                "skipping event (SEQNUM=%"PRIu64", ACTION=%s): %m",
+                                                event->seqnum, strna(device_action_to_string(event->action)));
+
+        if (event->retry_again_timeout_usec > 0 && event->retry_again_timeout_usec <= now_usec)
+                return log_device_warning_errno(event->dev, SYNTHETIC_ERRNO(ETIMEDOUT),
+                                                "The underlying block device is locked by a process more than %s, "
+                                                "skipping event (SEQNUM=%"PRIu64", ACTION=%s).",
+                                                FORMAT_TIMESPAN(EVENT_RETRY_TIMEOUT_USEC, USEC_PER_MINUTE),
+                                                event->seqnum, strna(device_action_to_string(event->action)));
+
+        event->retry_again_next_usec = usec_add(now_usec, EVENT_RETRY_INTERVAL_USEC);
+        if (event->retry_again_timeout_usec == 0)
+                event->retry_again_timeout_usec = usec_add(now_usec, EVENT_RETRY_TIMEOUT_USEC);
+
+        r = event_reset_time_relative(event->manager->event, &event->retry_event_source,
+                                      CLOCK_MONOTONIC, EVENT_RETRY_INTERVAL_USEC, 0,
+                                      on_event_retry, NULL,
+                                      0, "retry-event", true);
+        if (r < 0)
+                return log_device_warning_errno(event->dev, r, "Failed to reset timer event source for retrying event, "
+                                                "skipping event (SEQNUM=%"PRIu64", ACTION=%s): %m",
+                                                event->seqnum, strna(device_action_to_string(event->action)));
+
+        if (event->worker && event->worker->event == event)
+                event->worker->event = NULL;
+        event->worker = NULL;
+
+        event->state = EVENT_QUEUED;
+        return 0;
+}
+
+static int event_queue_assume_block_device_unlocked(Manager *manager, sd_device *dev) {
+        const char *devname;
+        int r;
+
+        /* When a new event for a block device is queued or we get an inotify event, assume that the
+         * device is not locked anymore. The assumption may not be true, but that should not cause any
+         * issues, as in that case events will be requeued soon. */
+
+        r = udev_get_whole_disk(dev, NULL, &devname);
+        if (r <= 0)
+                return r;
+
+        LIST_FOREACH(event, event, manager->events) {
+                const char *event_devname;
+
+                if (event->state != EVENT_QUEUED)
+                        continue;
+
+                if (event->retry_again_next_usec == 0)
+                        continue;
+
+                if (udev_get_whole_disk(event->dev, NULL, &event_devname) <= 0)
+                        continue;
+
+                if (!streq(devname, event_devname))
+                        continue;
+
+                event->retry_again_next_usec = 0;
+        }
+
+        return 0;
+}
+
+static int event_queue_insert(Manager *manager, sd_device *dev) {
+        const char *devpath, *devpath_old = NULL, *id = NULL, *devnode = NULL;
+        sd_device_action_t action;
+        uint64_t seqnum;
+        Event *event;
+        int r;
+
+        assert(manager);
+        assert(dev);
+
+        /* We only accepts devices received by device monitor. */
+        r = sd_device_get_seqnum(dev, &seqnum);
+        if (r < 0)
+                return r;
+
+        r = sd_device_get_action(dev, &action);
+        if (r < 0)
+                return r;
+
+        r = sd_device_get_devpath(dev, &devpath);
+        if (r < 0)
+                return r;
+
+        r = sd_device_get_property_value(dev, "DEVPATH_OLD", &devpath_old);
+        if (r < 0 && r != -ENOENT)
+                return r;
+
+        r = device_get_device_id(dev, &id);
+        if (r < 0 && r != -ENOENT)
+                return r;
+
+        r = sd_device_get_devname(dev, &devnode);
+        if (r < 0 && r != -ENOENT)
+                return r;
+
+        event = new(Event, 1);
+        if (!event)
+                return -ENOMEM;
+
+        *event = (Event) {
+                .manager = manager,
+                .dev = sd_device_ref(dev),
+                .seqnum = seqnum,
+                .action = action,
+                .id = id,
+                .devpath = devpath,
+                .devpath_old = devpath_old,
+                .devnode = devnode,
+                .state = EVENT_QUEUED,
+        };
+
+        if (!manager->events) {
+                r = touch("/run/udev/queue");
+                if (r < 0)
+                        log_warning_errno(r, "Failed to touch /run/udev/queue, ignoring: %m");
+        }
+
+        LIST_APPEND(event, manager->events, event);
+
+        log_device_uevent(dev, "Device is queued");
+
+        return 0;
+}
+
+static int on_uevent(sd_device_monitor *monitor, sd_device *dev, void *userdata) {
+        Manager *manager = ASSERT_PTR(userdata);
+        int r;
+
+        DEVICE_TRACE_POINT(kernel_uevent_received, dev);
+
+        device_ensure_usec_initialized(dev, NULL);
+
+        r = event_queue_insert(manager, dev);
+        if (r < 0) {
+                log_device_error_errno(dev, r, "Failed to insert device into event queue: %m");
+                return 1;
+        }
+
+        (void) event_queue_assume_block_device_unlocked(manager, dev);
+
+        return 1;
+}
+
+static int on_worker(sd_event_source *s, int fd, uint32_t revents, void *userdata) {
+        Manager *manager = ASSERT_PTR(userdata);
+
+        for (;;) {
+                EventResult result;
+                struct iovec iovec = IOVEC_MAKE(&result, sizeof(result));
+                CMSG_BUFFER_TYPE(CMSG_SPACE(sizeof(struct ucred))) control;
+                struct msghdr msghdr = {
+                        .msg_iov = &iovec,
+                        .msg_iovlen = 1,
+                        .msg_control = &control,
+                        .msg_controllen = sizeof(control),
+                };
+                ssize_t size;
+                struct ucred *ucred;
+                Worker *worker;
+
+                size = recvmsg_safe(fd, &msghdr, MSG_DONTWAIT);
+                if (size == -EINTR)
+                        continue;
+                if (size == -EAGAIN)
+                        /* nothing more to read */
+                        break;
+                if (size < 0)
+                        return log_error_errno(size, "Failed to receive message: %m");
+
+                cmsg_close_all(&msghdr);
+
+                if (size != sizeof(result)) {
+                        log_warning("Ignoring worker message with invalid size %zi bytes", size);
+                        continue;
+                }
+
+                ucred = CMSG_FIND_DATA(&msghdr, SOL_SOCKET, SCM_CREDENTIALS, struct ucred);
+                if (!ucred || ucred->pid <= 0) {
+                        log_warning("Ignoring worker message without valid PID");
+                        continue;
+                }
+
+                /* lookup worker who sent the signal */
+                worker = hashmap_get(manager->workers, PID_TO_PTR(ucred->pid));
+                if (!worker) {
+                        log_debug("Worker ["PID_FMT"] returned, but is no longer tracked", ucred->pid);
+                        continue;
+                }
+
+                if (worker->state == WORKER_KILLING) {
+                        worker->state = WORKER_KILLED;
+                        (void) kill(worker->pid, SIGTERM);
+                } else if (worker->state != WORKER_KILLED)
+                        worker->state = WORKER_IDLE;
+
+                /* worker returned */
+                if (result == EVENT_RESULT_TRY_AGAIN &&
+                    event_requeue(worker->event) < 0)
+                        udev_broadcast_result(manager->monitor, worker->event->dev, -ETIMEDOUT);
+
+                /* When event_requeue() succeeds, worker->event is NULL, and event_free() handles NULL gracefully. */
+                event_free(worker->event);
+        }
+
+        return 1;
+}
+
+static void manager_set_default_children_max(Manager *manager) {
+        uint64_t cpu_limit, mem_limit, cpu_count = 1;
+        int r;
+
+        assert(manager);
+
+        if (manager->children_max != 0)
+                return;
+
+        r = cpus_in_affinity_mask();
+        if (r < 0)
+                log_warning_errno(r, "Failed to determine number of local CPUs, ignoring: %m");
+        else
+                cpu_count = r;
+
+        cpu_limit = cpu_count * 2 + 16;
+        mem_limit = MAX(physical_memory() / (128*1024*1024), UINT64_C(10));
+
+        manager->children_max = MIN3(cpu_limit, mem_limit, WORKER_NUM_MAX);
+        log_debug("Set children_max to %u", manager->children_max);
+}
+
+/* receive the udevd message from userspace */
+static int on_ctrl_msg(UdevCtrl *uctrl, UdevCtrlMessageType type, const UdevCtrlMessageValue *value, void *userdata) {
+        Manager *manager = ASSERT_PTR(userdata);
+        int r;
+
+        assert(value);
+
+        switch (type) {
+        case UDEV_CTRL_SET_LOG_LEVEL:
+                if ((value->intval & LOG_PRIMASK) != value->intval) {
+                        log_debug("Received invalid udev control message (SET_LOG_LEVEL, %i), ignoring.", value->intval);
+                        break;
+                }
+
+                log_debug("Received udev control message (SET_LOG_LEVEL), setting log_level=%i", value->intval);
+
+                r = log_get_max_level();
+                if (r == value->intval)
+                        break;
+
+                log_set_max_level(value->intval);
+                manager->log_level = value->intval;
+                manager_kill_workers(manager, false);
+                break;
+        case UDEV_CTRL_STOP_EXEC_QUEUE:
+                log_debug("Received udev control message (STOP_EXEC_QUEUE)");
+                manager->stop_exec_queue = true;
+                break;
+        case UDEV_CTRL_START_EXEC_QUEUE:
+                log_debug("Received udev control message (START_EXEC_QUEUE)");
+                manager->stop_exec_queue = false;
+                /* It is not necessary to call event_queue_start() here, as it will be called in on_post() if necessary. */
+                break;
+        case UDEV_CTRL_RELOAD:
+                log_debug("Received udev control message (RELOAD)");
+                manager_reload(manager, /* force = */ true);
+                break;
+        case UDEV_CTRL_SET_ENV: {
+                _unused_ _cleanup_free_ char *old_val = NULL, *old_key = NULL;
+                _cleanup_free_ char *key = NULL, *val = NULL;
+                const char *eq;
+
+                eq = strchr(value->buf, '=');
+                if (!eq) {
+                        log_error("Invalid key format '%s'", value->buf);
+                        return 1;
+                }
+
+                key = strndup(value->buf, eq - value->buf);
+                if (!key) {
+                        log_oom();
+                        return 1;
+                }
+
+                old_val = hashmap_remove2(manager->properties, key, (void **) &old_key);
+
+                r = hashmap_ensure_allocated(&manager->properties, &string_hash_ops);
+                if (r < 0) {
+                        log_oom();
+                        return 1;
+                }
+
+                eq++;
+                if (isempty(eq))
+                        log_debug("Received udev control message (ENV), unsetting '%s'", key);
+                else {
+                        val = strdup(eq);
+                        if (!val) {
+                                log_oom();
+                                return 1;
+                        }
+
+                        log_debug("Received udev control message (ENV), setting '%s=%s'", key, val);
+
+                        r = hashmap_put(manager->properties, key, val);
+                        if (r < 0) {
+                                log_oom();
+                                return 1;
+                        }
+                }
+
+                key = val = NULL;
+                manager_kill_workers(manager, false);
+                break;
+        }
+        case UDEV_CTRL_SET_CHILDREN_MAX:
+                if (value->intval < 0) {
+                        log_debug("Received invalid udev control message (SET_MAX_CHILDREN, %i), ignoring.", value->intval);
+                        return 0;
+                }
+
+                log_debug("Received udev control message (SET_MAX_CHILDREN), setting children_max=%i", value->intval);
+                manager->children_max = value->intval;
+
+                /* When 0 is specified, determine the maximum based on the system resources. */
+                manager_set_default_children_max(manager);
+
+                notify_ready(manager);
+                break;
+        case UDEV_CTRL_PING:
+                log_debug("Received udev control message (PING)");
+                break;
+        case UDEV_CTRL_EXIT:
+                log_debug("Received udev control message (EXIT)");
+                manager_exit(manager);
+                break;
+        default:
+                log_debug("Received unknown udev control message, ignoring");
+        }
+
+        return 1;
+}
+
+static int synthesize_change_one(sd_device *dev, sd_device *target) {
+        int r;
+
+        if (DEBUG_LOGGING) {
+                const char *syspath = NULL;
+                (void) sd_device_get_syspath(target, &syspath);
+                log_device_debug(dev, "device is closed, synthesising 'change' on %s", strna(syspath));
+        }
+
+        r = sd_device_trigger(target, SD_DEVICE_CHANGE);
+        if (r < 0)
+                return log_device_debug_errno(target, r, "Failed to trigger 'change' uevent: %m");
+
+        DEVICE_TRACE_POINT(synthetic_change_event, dev);
+
+        return 0;
+}
+
+static int synthesize_change(sd_device *dev) {
+        _cleanup_(sd_device_enumerator_unrefp) sd_device_enumerator *e = NULL;
+        bool part_table_read;
+        const char *sysname;
+        int r, k;
+
+        r = sd_device_get_sysname(dev, &sysname);
+        if (r < 0)
+                return r;
+
+        if (startswith(sysname, "dm-") || block_device_is_whole_disk(dev) <= 0)
+                return synthesize_change_one(dev, dev);
+
+        r = blockdev_reread_partition_table(dev);
+        if (r < 0)
+                log_device_debug_errno(dev, r, "Failed to re-read partition table, ignoring: %m");
+        part_table_read = r >= 0;
+
+        /* search for partitions */
+        r = partition_enumerator_new(dev, &e);
+        if (r < 0)
+                return r;
+
+        /* We have partitions and re-read the table, the kernel already sent out a "change"
+         * event for the disk, and "remove/add" for all partitions. */
+        if (part_table_read && sd_device_enumerator_get_device_first(e))
+                return 0;
+
+        /* We have partitions but re-reading the partition table did not work, synthesize
+         * "change" for the disk and all partitions. */
+        r = synthesize_change_one(dev, dev);
+        FOREACH_DEVICE(e, d) {
+                k = synthesize_change_one(dev, d);
+                if (k < 0 && r >= 0)
+                        r = k;
+        }
+
+        return r;
+}
+
+static int on_inotify(sd_event_source *s, int fd, uint32_t revents, void *userdata) {
+        Manager *manager = ASSERT_PTR(userdata);
+        union inotify_event_buffer buffer;
+        ssize_t l;
+        int r;
+
+        l = read(fd, &buffer, sizeof(buffer));
+        if (l < 0) {
+                if (ERRNO_IS_TRANSIENT(errno))
+                        return 0;
+
+                return log_error_errno(errno, "Failed to read inotify fd: %m");
+        }
+
+        FOREACH_INOTIFY_EVENT_WARN(e, buffer, l) {
+                _cleanup_(sd_device_unrefp) sd_device *dev = NULL;
+                const char *devnode;
+
+                /* Do not handle IN_IGNORED here. Especially, do not try to call udev_watch_end() from the
+                 * main process. Otherwise, the pair of the symlinks may become inconsistent, and several
+                 * garbage may remain. The old symlinks are removed by a worker that processes the
+                 * corresponding 'remove' uevent;
+                 * udev_event_execute_rules() -> event_execute_rules_on_remove() -> udev_watch_end(). */
+
+                if (!FLAGS_SET(e->mask, IN_CLOSE_WRITE))
+                        continue;
+
+                r = device_new_from_watch_handle(&dev, e->wd);
+                if (r < 0) {
+                        /* Device may be removed just after closed. */
+                        log_debug_errno(r, "Failed to create sd_device object from watch handle, ignoring: %m");
+                        continue;
+                }
+
+                r = sd_device_get_devname(dev, &devnode);
+                if (r < 0) {
+                        /* Also here, device may be already removed. */
+                        log_device_debug_errno(dev, r, "Failed to get device node, ignoring: %m");
+                        continue;
+                }
+
+                log_device_debug(dev, "Received inotify event for %s.", devnode);
+
+                (void) event_queue_assume_block_device_unlocked(manager, dev);
+                (void) synthesize_change(dev);
+        }
+
+        return 0;
+}
+
+static int on_sigterm(sd_event_source *s, const struct signalfd_siginfo *si, void *userdata) {
+        Manager *manager = ASSERT_PTR(userdata);
+
+        manager_exit(manager);
+
+        return 1;
+}
+
+static int on_sighup(sd_event_source *s, const struct signalfd_siginfo *si, void *userdata) {
+        Manager *manager = ASSERT_PTR(userdata);
+
+        manager_reload(manager, /* force = */ true);
+
+        return 1;
+}
+
+static int on_sigchld(sd_event_source *s, const siginfo_t *si, void *userdata) {
+        Worker *worker = ASSERT_PTR(userdata);
+        Manager *manager = ASSERT_PTR(worker->manager);
+        sd_device *dev = worker->event ? ASSERT_PTR(worker->event->dev) : NULL;
+        EventResult result;
+
+        assert(si);
+
+        switch (si->si_code) {
+        case CLD_EXITED:
+                if (si->si_status == 0)
+                        log_device_debug(dev, "Worker ["PID_FMT"] exited.", si->si_pid);
+                else
+                        log_device_warning(dev, "Worker ["PID_FMT"] exited with return code %i.",
+                                           si->si_pid, si->si_status);
+                result = EVENT_RESULT_EXIT_STATUS_BASE + si->si_status;
+                break;
+
+        case CLD_KILLED:
+        case CLD_DUMPED:
+                log_device_warning(dev, "Worker ["PID_FMT"] terminated by signal %i (%s).",
+                                   si->si_pid, si->si_status, signal_to_string(si->si_status));
+                result = EVENT_RESULT_SIGNAL_BASE + si->si_status;
+                break;
+
+        default:
+                assert_not_reached();
+        }
+
+        if (result != EVENT_RESULT_SUCCESS && dev) {
+                /* delete state from disk */
+                device_delete_db(dev);
+                device_tag_index(dev, NULL, false);
+
+                /* Forward kernel event to libudev listeners */
+                udev_broadcast_result(manager->monitor, dev, result);
+        }
+
+        worker_free(worker);
+
+        return 1;
+}
+
+static int on_post(sd_event_source *s, void *userdata) {
+        Manager *manager = ASSERT_PTR(userdata);
+
+        if (manager->events) {
+                /* Try to process pending events if idle workers exist. Why is this necessary?
+                 * When a worker finished an event and became idle, even if there was a pending event,
+                 * the corresponding device might have been locked and the processing of the event
+                 * delayed for a while, preventing the worker from processing the event immediately.
+                 * Now, the device may be unlocked. Let's try again! */
+                event_queue_start(manager);
+                return 1;
+        }
+
+        /* There are no queued events. Let's remove /run/udev/queue and clean up the idle processes. */
+
+        if (unlink("/run/udev/queue") < 0) {
+                if (errno != ENOENT)
+                        log_warning_errno(errno, "Failed to unlink /run/udev/queue, ignoring: %m");
+        } else
+                log_debug("No events are queued, removing /run/udev/queue.");
+
+        if (!hashmap_isempty(manager->workers)) {
+                /* There are idle workers */
+                (void) event_reset_time_relative(manager->event, &manager->kill_workers_event,
+                                                 CLOCK_MONOTONIC, 3 * USEC_PER_SEC, USEC_PER_SEC,
+                                                 on_kill_workers_event, manager,
+                                                 0, "kill-workers-event", false);
+                return 1;
+        }
+
+        /* There are no idle workers. */
+
+        if (manager->udev_node_needs_cleanup) {
+                (void) udev_node_cleanup();
+                manager->udev_node_needs_cleanup = false;
+        }
+
+        if (manager->exit)
+                return sd_event_exit(manager->event, 0);
+
+        if (manager->cgroup)
+                /* cleanup possible left-over processes in our cgroup */
+                (void) cg_kill(manager->cgroup, SIGKILL, CGROUP_IGNORE_SELF, /* set=*/ NULL, /* kill_log= */ NULL, /* userdata= */ NULL);
+
+        return 1;
+}
+
+Manager* manager_new(void) {
+        Manager *manager;
+
+        manager = new(Manager, 1);
+        if (!manager)
+                return NULL;
+
+        *manager = (Manager) {
+                .inotify_fd = -EBADF,
+                .worker_watch = EBADF_PAIR,
+                .log_level = LOG_INFO,
+                .resolve_name_timing = RESOLVE_NAME_EARLY,
+                .timeout_usec = 180 * USEC_PER_SEC,
+                .timeout_signal = SIGKILL,
+        };
+
+        return manager;
+}
+
+int manager_init(Manager *manager, int fd_ctrl, int fd_uevent) {
+        _cleanup_free_ char *cgroup = NULL;
+        int r;
+
+        assert(manager);
+
+        r = udev_ctrl_new_from_fd(&manager->ctrl, fd_ctrl);
+        if (r < 0)
+                return log_error_errno(r, "Failed to initialize udev control socket: %m");
+
+        r = udev_ctrl_enable_receiving(manager->ctrl);
+        if (r < 0)
+                return log_error_errno(r, "Failed to bind udev control socket: %m");
+
+        r = device_monitor_new_full(&manager->monitor, MONITOR_GROUP_KERNEL, fd_uevent);
+        if (r < 0)
+                return log_error_errno(r, "Failed to initialize device monitor: %m");
+
+        (void) sd_device_monitor_set_description(manager->monitor, "manager");
+
+        r = device_monitor_enable_receiving(manager->monitor);
+        if (r < 0)
+                return log_error_errno(r, "Failed to bind netlink socket: %m");
+
+        manager->log_level = log_get_max_level();
+
+        r = cg_pid_get_path(SYSTEMD_CGROUP_CONTROLLER, 0, &cgroup);
+        if (r < 0)
+                log_debug_errno(r, "Failed to get cgroup, ignoring: %m");
+        else if (endswith(cgroup, "/udev")) { /* If we are in a subcgroup /udev/ we assume it was delegated to us */
+                log_debug("Running in delegated subcgroup '%s'.", cgroup);
+                manager->cgroup = TAKE_PTR(cgroup);
+        }
+
+        return 0;
+}
+
+int manager_main(Manager *manager) {
+        int fd_worker, r;
+
+        manager_set_default_children_max(manager);
+
+        /* unnamed socket from workers to the main daemon */
+        r = socketpair(AF_UNIX, SOCK_DGRAM|SOCK_CLOEXEC, 0, manager->worker_watch);
+        if (r < 0)
+                return log_error_errno(errno, "Failed to create socketpair for communicating with workers: %m");
+
+        fd_worker = manager->worker_watch[READ_END];
+
+        r = setsockopt_int(fd_worker, SOL_SOCKET, SO_PASSCRED, true);
+        if (r < 0)
+                return log_error_errno(r, "Failed to enable SO_PASSCRED: %m");
+
+        manager->inotify_fd = inotify_init1(IN_CLOEXEC);
+        if (manager->inotify_fd < 0)
+                return log_error_errno(errno, "Failed to create inotify descriptor: %m");
+
+        udev_watch_restore(manager->inotify_fd);
+
+        /* block and listen to all signals on signalfd */
+        assert_se(sigprocmask_many(SIG_BLOCK, NULL, SIGTERM, SIGINT, SIGHUP, SIGCHLD, SIGRTMIN+18, -1) >= 0);
+
+        r = sd_event_default(&manager->event);
+        if (r < 0)
+                return log_error_errno(r, "Failed to allocate event loop: %m");
+
+        r = sd_event_add_signal(manager->event, NULL, SIGINT, on_sigterm, manager);
+        if (r < 0)
+                return log_error_errno(r, "Failed to create SIGINT event source: %m");
+
+        r = sd_event_add_signal(manager->event, NULL, SIGTERM, on_sigterm, manager);
+        if (r < 0)
+                return log_error_errno(r, "Failed to create SIGTERM event source: %m");
+
+        r = sd_event_add_signal(manager->event, NULL, SIGHUP, on_sighup, manager);
+        if (r < 0)
+                return log_error_errno(r, "Failed to create SIGHUP event source: %m");
+
+        r = sd_event_set_watchdog(manager->event, true);
+        if (r < 0)
+                return log_error_errno(r, "Failed to create watchdog event source: %m");
+
+        r = udev_ctrl_attach_event(manager->ctrl, manager->event);
+        if (r < 0)
+                return log_error_errno(r, "Failed to attach event to udev control: %m");
+
+        r = udev_ctrl_start(manager->ctrl, on_ctrl_msg, manager);
+        if (r < 0)
+                return log_error_errno(r, "Failed to start udev control: %m");
+
+        /* This needs to be after the inotify and uevent handling, to make sure
+         * that the ping is send back after fully processing the pending uevents
+         * (including the synthetic ones we may create due to inotify events).
+         */
+        r = sd_event_source_set_priority(udev_ctrl_get_event_source(manager->ctrl), SD_EVENT_PRIORITY_IDLE);
+        if (r < 0)
+                return log_error_errno(r, "Failed to set IDLE event priority for udev control event source: %m");
+
+        r = sd_event_add_io(manager->event, &manager->inotify_event, manager->inotify_fd, EPOLLIN, on_inotify, manager);
+        if (r < 0)
+                return log_error_errno(r, "Failed to create inotify event source: %m");
+
+        r = sd_device_monitor_attach_event(manager->monitor, manager->event);
+        if (r < 0)
+                return log_error_errno(r, "Failed to attach event to device monitor: %m");
+
+        r = sd_device_monitor_start(manager->monitor, on_uevent, manager);
+        if (r < 0)
+                return log_error_errno(r, "Failed to start device monitor: %m");
+
+        r = sd_event_add_io(manager->event, NULL, fd_worker, EPOLLIN, on_worker, manager);
+        if (r < 0)
+                return log_error_errno(r, "Failed to create worker event source: %m");
+
+        r = sd_event_add_post(manager->event, NULL, on_post, manager);
+        if (r < 0)
+                return log_error_errno(r, "Failed to create post event source: %m");
+
+        /* Eventually, we probably want to do more here on memory pressure, for example, kill idle workers immediately */
+        r = sd_event_add_memory_pressure(manager->event, &manager->memory_pressure_event_source, NULL, NULL);
+        if (r < 0)
+                log_full_errno(ERRNO_IS_NOT_SUPPORTED(r) || ERRNO_IS_PRIVILEGE(r) || (r == -EHOSTDOWN) ? LOG_DEBUG : LOG_WARNING, r,
+                               "Failed to allocate memory pressure watch, ignoring: %m");
+
+        r = sd_event_add_signal(manager->event, &manager->memory_pressure_event_source, SIGRTMIN+18, sigrtmin18_handler, NULL);
+        if (r < 0)
+                return log_error_errno(r, "Failed to allocate SIGRTMIN+18 event source, ignoring: %m");
+
+        manager->last_usec = now(CLOCK_MONOTONIC);
+
+        udev_builtin_init();
+
+        r = udev_rules_load(&manager->rules, manager->resolve_name_timing);
+        if (r < 0)
+                return log_error_errno(r, "Failed to read udev rules: %m");
+
+        r = udev_rules_apply_static_dev_perms(manager->rules);
+        if (r < 0)
+                log_warning_errno(r, "Failed to apply permissions on static device nodes, ignoring: %m");
+
+        notify_ready(manager);
+
+        r = sd_event_loop(manager->event);
+        if (r < 0)
+                log_error_errno(r, "Event loop failed: %m");
+
+        (void) sd_notify(/* unset= */ false, NOTIFY_STOPPING);
+        return r;
+}