LINUX_TOSTOP
bts->c_lflag |= cvtto_bsd_mask(lt->c_lflag, LINUX_TOSTOP, TOSTOP);
lt->c_lflag |= cvtto_linux_mask(bts->c_lflag, TOSTOP, LINUX_TOSTOP);
bts->c_lflag |= cvtto_bsd_mask(lts->c_lflag, LINUX_TOSTOP, TOSTOP);
lts->c_lflag |= cvtto_linux_mask(bts->c_lflag, TOSTOP, LINUX_TOSTOP);