logind: make unit/job active checking more debuggable

Let's log the error messages if we get any at debug level.

src/login/logind-dbus.c

@@ -3130,7 +3130,7 @@ int manager_kill_unit(Manager *manager, const char *unit, KillWho who, int signo
                         "ssi", unit, who == KILL_LEADER ? "main" : "all", signo);
 }
 
-int manager_unit_is_active(Manager *manager, const char *unit) {
+int manager_unit_is_active(Manager *manager, const char *unit, sd_bus_error *ret_error) {
         _cleanup_(sd_bus_error_free) sd_bus_error error = SD_BUS_ERROR_NULL;
         _cleanup_(sd_bus_message_unrefp) sd_bus_message *reply = NULL;
         _cleanup_free_ char *path = NULL;
@@ -3166,17 +3166,18 @@ int manager_unit_is_active(Manager *manager, const char *unit) {
                     sd_bus_error_has_name(&error, BUS_ERROR_LOAD_FAILED))
                         return false;
 
+                sd_bus_error_move(ret_error, &error);
                 return r;
         }
 
         r = sd_bus_message_read(reply, "s", &state);
         if (r < 0)
-                return -EINVAL;
+                return r;
 
-        return !streq(state, "inactive") && !streq(state, "failed");
+        return !STR_IN_SET(state, "inactive", "failed");
 }
 
-int manager_job_is_active(Manager *manager, const char *path) {
+int manager_job_is_active(Manager *manager, const char *path, sd_bus_error *ret_error) {
         _cleanup_(sd_bus_error_free) sd_bus_error error = SD_BUS_ERROR_NULL;
         _cleanup_(sd_bus_message_unrefp) sd_bus_message *reply = NULL;
         int r;
@@ -3201,6 +3202,7 @@ int manager_job_is_active(Manager *manager, const char *path) {
                 if (sd_bus_error_has_name(&error, SD_BUS_ERROR_UNKNOWN_OBJECT))
                         return false;
 
+                sd_bus_error_move(ret_error, &error);
                 return r;
         }
 

src/login/logind-session.c

@@ -1008,6 +1008,8 @@ static void session_remove_fifo(Session *s) {
 }
 
 bool session_may_gc(Session *s, bool drop_not_started) {
+        int r;
+
         assert(s);
 
         if (drop_not_started && !s->started)
@@ -1021,11 +1023,25 @@ bool session_may_gc(Session *s, bool drop_not_started) {
                         return false;
         }
 
-        if (s->scope_job && manager_job_is_active(s->manager, s->scope_job))
-                return false;
+        if (s->scope_job) {
+                _cleanup_(sd_bus_error_free) sd_bus_error error = SD_BUS_ERROR_NULL;
 
-        if (s->scope && manager_unit_is_active(s->manager, s->scope))
-                return false;
+                r = manager_job_is_active(s->manager, s->scope_job, &error);
+                if (r < 0)
+                        log_debug_errno(r, "Failed to determine whether job '%s' is pending, ignoring: %s", s->scope_job, bus_error_message(&error, r));
+                if (r != 0)
+                        return false;
+        }
+
+        if (s->scope) {
+                _cleanup_(sd_bus_error_free) sd_bus_error error = SD_BUS_ERROR_NULL;
+
+                r = manager_unit_is_active(s->manager, s->scope, &error);
+                if (r < 0)
+                        log_debug_errno(r, "Failed to determine whether unit '%s' is active, ignoring: %s", s->scope, bus_error_message(&error, r));
+                if (r != 0)
+                        return false;
+        }
 
         return true;
 }

src/login/logind-user.c

@@ -534,6 +534,8 @@ int user_check_linger_file(User *u) {
 }
 
 bool user_may_gc(User *u, bool drop_not_started) {
+        int r;
+
         assert(u);
 
         if (drop_not_started && !u->started)
@@ -545,11 +547,19 @@ bool user_may_gc(User *u, bool drop_not_started) {
         if (user_check_linger_file(u) > 0)
                 return false;
 
-        if (u->slice_job && manager_job_is_active(u->manager, u->slice_job))
-                return false;
+        /* Check if our job is still pending */
+        if (u->service_job) {
+                _cleanup_(sd_bus_error_free) sd_bus_error error = SD_BUS_ERROR_NULL;
 
-        if (u->service_job && manager_job_is_active(u->manager, u->service_job))
-                return false;
+                r = manager_job_is_active(u->manager, u->service_job, &error);
+                if (r < 0)
+                        log_debug_errno(r, "Failed to determine whether job '%s' is pending, ignoring: %s", u->service_job, bus_error_message(&error, r));
+                if (r != 0)
+                        return false;
+        }
+
+        /* Note that we don't care if the three units we manage for each user object are up or not, as we are managing
+         * their state rather than tracking it. */
 
         return true;
 }

src/login/logind.h

@@ -166,8 +166,8 @@ int manager_start_unit(Manager *manager, const char *unit, sd_bus_error *error,
 int manager_stop_unit(Manager *manager, const char *unit, sd_bus_error *error, char **job);
 int manager_abandon_scope(Manager *manager, const char *scope, sd_bus_error *error);
 int manager_kill_unit(Manager *manager, const char *unit, KillWho who, int signo, sd_bus_error *error);
-int manager_unit_is_active(Manager *manager, const char *unit);
-int manager_job_is_active(Manager *manager, const char *path);
+int manager_unit_is_active(Manager *manager, const char *unit, sd_bus_error *error);
+int manager_job_is_active(Manager *manager, const char *path, sd_bus_error *error);
 
 /* gperf lookup function */
 const struct ConfigPerfItem* logind_gperf_lookup(const char *key, GPERF_LEN_TYPE length);