os/locks/rw_lock.cpp

23 rw_lock_wait(rw_lock *lock, bool writer)
30 	if (lock->waiters != NULL)
31 		lock->last_waiter->next = &waiter;
33 		lock->waiters = &waiter;
35 	lock->last_waiter = &waiter;
39 	mutex_unlock(&lock->lock);
46 	// and lock it again before returning
47 	mutex_lock(&lock->lock);
53 rw_lock_unblock(rw_lock *lock)
56 	if (lock->holder >= 0)
59 	rw_lock_waiter *waiter = lock->waiters;
64 		if (lock->reader_count > 0)
67 		lock->waiters = waiter->next;
68 		lock->holder = waiter->thread;
74 		lock->reader_count++;
75 		lock->waiters = waiter->next;
77 		waiter = lock->waiters;
83 __rw_lock_init(rw_lock *lock, const char *name)
85 	rw_lock_init_etc(lock, name, 0);
90 __rw_lock_init_etc(rw_lock *lock, const char *name, uint32 flags)
92 	lock->waiters = NULL;
93 	lock->holder = -1;
94 	lock->reader_count = 0;
95 	lock->writer_count = 0;
96 	lock->owner_count = 0;
97 	mutex_init_etc(&lock->lock, name, flags);
102 __rw_lock_destroy(rw_lock *lock)
104 	mutex_lock(&lock->lock);
106 	rw_lock_waiter *waiter = lock->waiters;
112 	mutex_destroy(&lock->lock);
117 __rw_lock_read_lock(rw_lock *lock)
119 	MutexLocker locker(lock->lock);
121 	if (lock->writer_count == 0) {
122 		lock->reader_count++;
126 	if (lock->holder == find_thread(NULL)) {
127 		lock->owner_count++;
131 	return rw_lock_wait(lock, false);
136 __rw_lock_read_unlock(rw_lock *lock)
138 	MutexLocker locker(lock->lock);
140 	if (lock->holder == find_thread(NULL)) {
141 		if (--lock->owner_count > 0)
144 		// this originally has been a write lock
145 		lock->writer_count--;
146 		lock->holder = -1;
148 		rw_lock_unblock(lock);
152 	if (lock->reader_count <= 0) {
157 	lock->reader_count--;
158 	rw_lock_unblock(lock);
164 __rw_lock_write_lock(rw_lock *lock)
166 	MutexLocker locker(lock->lock);
168 	if (lock->reader_count == 0 && lock->writer_count == 0) {
169 		lock->writer_count++;
170 		lock->holder = find_thread(NULL);
171 		lock->owner_count = 1;
175 	if (lock->holder == find_thread(NULL)) {
176 		lock->owner_count++;
180 	lock->writer_count++;
182 	status_t result = rw_lock_wait(lock, true);
186 	if (lock->holder != find_thread(NULL)) {
191 	lock->owner_count = 1;
197 __rw_lock_write_unlock(rw_lock *lock)
199 	MutexLocker locker(lock->lock);
201 	if (lock->holder != find_thread(NULL)) {
206 	if (--lock->owner_count > 0)
209 	lock->writer_count--;
210 	lock->holder = -1;
211 	rw_lock_unblock(lock);