V_tcp_sack_globalholes
V_tcp_sack_globalholes >= V_tcp_sack_globalmaxholes) {
atomic_add_int(&V_tcp_sack_globalholes, 1);
atomic_subtract_int(&V_tcp_sack_globalholes, 1);
KASSERT(V_tcp_sack_globalholes >= 0, ("tcp_sack_globalholes < 0"));