RWSEM_WRITER_MASK
if (!(atomic_long_read(&sem->count) & RWSEM_WRITER_MASK)) {
#define RWSEM_LOCK_MASK (RWSEM_WRITER_MASK|RWSEM_READER_MASK)
#define RWSEM_READ_FAILED_MASK (RWSEM_WRITER_MASK|RWSEM_FLAG_WAITERS|\
if (count & RWSEM_WRITER_MASK)
if (unlikely(oldcount & RWSEM_WRITER_MASK)) {
if (count & RWSEM_WRITER_MASK)