comm_str__refcnt
if (refcount_read(comm_str__refcnt(cs)) == 1) {
refcount_inc_not_zero(comm_str__refcnt(cs));
if (refcount_dec_and_test(comm_str__refcnt(cs))) {
if (refcount_read(comm_str__refcnt(cs)) == 1)
refcount_set(comm_str__refcnt(result), 1);