SQ_SERVICE
ASSERT((sq->sq_svcflags & SQ_SERVICE) == 0);
boolean_t bg_service = sq->sq_svcflags & SQ_SERVICE;
sq->sq_svcflags &= ~SQ_SERVICE;
ASSERT(!(sq->sq_svcflags & SQ_SERVICE));
sq->sq_svcflags |= SQ_SERVICE;