_Q_PENDING_BITS
#define _Q_TAIL_IDX_OFFSET (_Q_PENDING_OFFSET + _Q_PENDING_BITS)
#if _Q_PENDING_BITS == 8
#if _Q_PENDING_BITS == 8
#define _Q_TAIL_IDX_OFFSET (_Q_PENDING_OFFSET + _Q_PENDING_BITS)