SPCF_ITIMER
atomic_setbits_int(&spc->spc_schedflags, SPCF_ITIMER);
if (ISSET(spc->spc_schedflags, SPCF_ITIMER)) {
atomic_clearbits_int(&spc->spc_schedflags, SPCF_ITIMER);
if (ISSET(spc->spc_schedflags, SPCF_ITIMER)) {
atomic_clearbits_int(&spc->spc_schedflags, SPCF_ITIMER);
atomic_setbits_int(&spc->spc_schedflags, SPCF_ITIMER);