SID_DELETE
if (sidp->sid_flags & SID_DELETE) {
atomic_or_uint(&sidp->sid_flags, SID_DELETE);
atomic_or_uint(&sidp->sid_flags, SID_DELETE);
if (sidp->sid_flags & SID_DELETE) {
sidp->sid_flags &= ~(SID_DELETE);
((sidp)->sid_flags & SID_DELETE) || \