RW_READ_COUNT_SHIFT
#define RW_READ_INCR (1 << RW_READ_COUNT_SHIFT)
newown += rcnt << RW_READ_COUNT_SHIFT;
newown += (rcnt << RW_READ_COUNT_SHIFT) + RW_READ_INCR;
#define RW_READ_INCR (1UL << RW_READ_COUNT_SHIFT)