SQ_BGTHREAD
ASSERT(sq->sq_svcflags & SQ_BGTHREAD);
if (sq->sq_svcflags & SQ_BGTHREAD) {
sq->sq_svcflags &= ~SQ_BGTHREAD;
IMPLY(sq->sq_next != NULL, sq->sq_svcflags & SQ_BGTHREAD);
if (sq->sq_svcflags & (SQ_DISABLED | SQ_BGTHREAD))
sq->sq_svcflags |= SQ_BGTHREAD;
if (sq->sq_svcflags & SQ_BGTHREAD)
sq->sq_svcflags &= ~SQ_BGTHREAD;