8  *  2) Remove the reader BIAS to force readers into the slow path
9  *  3) Wait until all readers have left the critical section
14  *  2) Set the reader BIAS, so readers can use the fast path again
15  *  3) Unlock rtmutex, to release blocked readers
34  * active readers. A blocked writer would force all newly incoming readers
45  * The lock/unlock of readers can run in fast paths: lock and unlock are only
58 	 * Increment reader count, if sem->readers < 0, i.e. READER_BIAS is  in rwbase_read_trylock()
61 	for (r = atomic_read(&rwb->readers); r < 0;) {  in rwbase_read_trylock()
63 		if (likely(atomic_try_cmpxchg(&rwb->readers, &r, r + 1)))  in rwbase_read_trylock()
77 	 * Allow readers, as long as the writer has not completely  in __rwbase_read_lock()
80 	if (atomic_read(&rwb->readers) != WRITER_BIAS) {  in __rwbase_read_lock()
81 		atomic_inc(&rwb->readers);  in __rwbase_read_lock()
130 		atomic_inc(&rwb->readers);  in __rwbase_read_lock()
156 	 * clean up rwb->readers it needs to acquire rtm->wait_lock. The  in __rwbase_read_unlock()
170 	 * rwb->readers can only hit 0 when a writer is waiting for the  in rwbase_read_unlock()
171 	 * active readers to leave the critical section.  in rwbase_read_unlock()
175 	if (unlikely(atomic_dec_and_test(&rwb->readers)))  in rwbase_read_unlock()
188 	(void)atomic_add_return_release(READER_BIAS - bias, &rwb->readers);  in __rwbase_write_unlock()
221 	if (!atomic_read_acquire(&rwb->readers)) {  in __rwbase_write_trylock()
222 		atomic_set(&rwb->readers, WRITER_BIAS);  in __rwbase_write_trylock()
239 	/* Force readers into slow path */  in rwbase_write_lock()
240 	atomic_sub(READER_BIAS, &rwb->readers);  in rwbase_write_lock()
279 	atomic_sub(READER_BIAS, &rwb->readers);  in rwbase_write_trylock()