double_unlock_hb
double_unlock_hb(hb1, hb2);
double_unlock_hb(hb1, hb2);
double_unlock_hb(hb1, hb2);
double_unlock_hb(hb1, hb2);
double_unlock_hb(hb1, hb2);
double_unlock_hb(hb1, hb2);