US_FLIDX_SG_ACTIVE
set_bit(US_FLIDX_SG_ACTIVE, &us->dflags);
if (test_and_clear_bit(US_FLIDX_SG_ACTIVE, &us->dflags)) {
clear_bit(US_FLIDX_SG_ACTIVE, &us->dflags);
if (test_and_clear_bit(US_FLIDX_SG_ACTIVE, &us->dflags)) {