udev,network: skip reloading if already in stopping state (#43504)

Prompted by #43482.

src/network/networkd-manager.c

@@ -515,6 +515,8 @@ static int manager_stop(Manager *manager, ManagerState state) {
                 assert_not_reached();
         }
 
+        (void) sd_notify(/* unset_environment= */ false, NOTIFY_STOPPING_MESSAGE);
+
         manager->state = state;
 
         Link *link;
@@ -1273,6 +1275,9 @@ int manager_reload(Manager *m, sd_bus_message *message, sd_varlink *varlink, boo
         assert(m);
         assert(!message || !varlink); /* D-Bus and Varlink callers are mutually exclusive */
 
+        if (m->state != MANAGER_RUNNING)
+                return -ESHUTDOWN; /* Refuse reloading if we are stopping or restarting. */
+
         log_debug("Reloading...");
         (void) notify_reloading();
 

src/udev/udev-manager.c

@@ -247,6 +247,9 @@ int manager_reset_kill_workers_timer(Manager *manager) {
 void manager_exit(Manager *manager) {
         assert(manager);
 
+        if (manager->exit)
+                return;
+
         manager->exit = true;
 
         (void) sd_notify(/* unset_environment= */ false, NOTIFY_STOPPING_MESSAGE);
@@ -277,6 +280,9 @@ void notify_ready(Manager *manager) {
 
         assert(manager);
 
+        if (manager->exit)
+                return;
+
         r = sd_notifyf(/* unset_environment= */ false,
                        "READY=1\n"
                        "STATUS=Processing with %u children at max", manager->config.children_max);
@@ -292,6 +298,9 @@ void manager_reload(Manager *manager, bool force) {
 
         assert(manager);
 
+        if (manager->exit)
+                return;
+
         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 */