sleep,home: always initialize UnitFreezer if used

Previously, unit_freezer_new_freeze() would only return
UnitFreezer object if FreezeUnit() succeeds. This is not
ideal though, as a failed bus call doesn't mean the action
actually failed. E.g. a timeout might occur because pid1
is waiting for cgroup event from kernel, while the bus call
timeout was exceeded (#33269). In such a case, ThawUnit()
will never be called, resulting in frozen units remain that
way after resuming from sleep.

Therefore, let's get rid of unit_freezer_new_freeze(),
and make sure as long as unit freezer is involved, we'll
call ThawUnit() when we're done. This should make things
a lot more robust.

1 files changed, 7 insertions, 3 deletions

diff --git a/src/sleep/sleep.c b/src/sleep/sleep.c
index 7e5075a63c..15ef7ae913 100644
--- a/src/sleep/sleep.c
+++ b/src/sleep/sleep.c
@@ -604,9 +604,13 @@ static int run(int argc, char *argv[]) {
         r = getenv_bool("SYSTEMD_SLEEP_FREEZE_USER_SESSIONS");
         if (r < 0 && r != -ENXIO)
                 log_warning_errno(r, "Cannot parse value of $SYSTEMD_SLEEP_FREEZE_USER_SESSIONS, ignoring: %m");
-        if (r != 0)
-                (void) unit_freezer_new_freeze(SPECIAL_USER_SLICE, &user_slice_freezer);
-        else
+        if (r != 0) {
+                r = unit_freezer_new(SPECIAL_USER_SLICE, &user_slice_freezer);
+                if (r < 0)
+                        return r;
+
+                (void) unit_freezer_freeze(user_slice_freezer);
+        } else
                 log_notice("User sessions remain unfrozen on explicit request ($SYSTEMD_SLEEP_FREEZE_USER_SESSIONS=0).\n"
                            "This is not recommended, and might result in unexpected behavior, particularly\n"
                            "in suspend-then-hibernate operations or setups with encrypted home directories.");