2  * Copyright 2011-2015 Samy Al Bahra.
10  * 2. Redistributions in binary form must reproduce the above copyright
31  * Big reader spinlocks provide cache-local contention-free read
37  * This implementation is thread-agnostic which comes at the cost
68 	br->readers = NULL;  in ck_brlock_init()
69 	br->writer = false;  in ck_brlock_init()
83 	while (ck_pr_fas_uint(&br->writer, true) == true)  in ck_brlock_write_lock()
89 	for (cursor = br->readers; cursor != NULL; cursor = cursor->next) {  in ck_brlock_write_lock()
90 		while (ck_pr_load_uint(&cursor->n_readers) != 0)  in ck_brlock_write_lock()
103 	ck_pr_store_uint(&br->writer, false);  in ck_brlock_write_unlock()
108 ck_brlock_write_trylock(struct ck_brlock *br, unsigned int factor)  in ck_brlock_write_trylock()  argument
113 	while (ck_pr_fas_uint(&br->writer, true) == true) {  in ck_brlock_write_trylock()
114 		if (++steps >= factor)  in ck_brlock_write_trylock()
126 	for (cursor = br->readers; cursor != NULL; cursor = cursor->next) {  in ck_brlock_write_trylock()
127 		while (ck_pr_load_uint(&cursor->n_readers) != 0) {  in ck_brlock_write_trylock()
128 			if (++steps >= factor) {  in ck_brlock_write_trylock()
145 	reader->n_readers = 0;  in ck_brlock_read_register()
146 	reader->previous = NULL;  in ck_brlock_read_register()
151 	reader->next = ck_pr_load_ptr(&br->readers);  in ck_brlock_read_register()
152 	if (reader->next != NULL)  in ck_brlock_read_register()
153 		reader->next->previous = reader;  in ck_brlock_read_register()
154 	ck_pr_store_ptr(&br->readers, reader);  in ck_brlock_read_register()
166 	if (reader->next != NULL)  in ck_brlock_read_unregister()
167 		reader->next->previous = reader->previous;  in ck_brlock_read_unregister()
169 	if (reader->previous != NULL)  in ck_brlock_read_unregister()
170 		reader->previous->next = reader->next;  in ck_brlock_read_unregister()
172 		br->readers = reader->next;  in ck_brlock_read_unregister()
182 	if (reader->n_readers >= 1) {  in ck_brlock_read_lock()
183 		ck_pr_store_uint(&reader->n_readers, reader->n_readers + 1);  in ck_brlock_read_lock()
188 		while (ck_pr_load_uint(&br->writer) == true)  in ck_brlock_read_lock()
192 		ck_pr_fas_uint(&reader->n_readers, 1);  in ck_brlock_read_lock()
200 		ck_pr_store_uint(&reader->n_readers, 1);  in ck_brlock_read_lock()
209 		if (ck_pr_load_uint(&br->writer) == false)  in ck_brlock_read_lock()
212 		ck_pr_store_uint(&reader->n_readers, 0);  in ck_brlock_read_lock()
222 		       unsigned int factor)  in ck_brlock_read_trylock()  argument
226 	if (reader->n_readers >= 1) {  in ck_brlock_read_trylock()
227 		ck_pr_store_uint(&reader->n_readers, reader->n_readers + 1);  in ck_brlock_read_trylock()
232 		while (ck_pr_load_uint(&br->writer) == true) {  in ck_brlock_read_trylock()
233 			if (++steps >= factor)  in ck_brlock_read_trylock()
240 		ck_pr_fas_uint(&reader->n_readers, 1);  in ck_brlock_read_trylock()
248 		ck_pr_store_uint(&reader->n_readers, 1);  in ck_brlock_read_trylock()
257 		if (ck_pr_load_uint(&br->writer) == false)  in ck_brlock_read_trylock()
260 		ck_pr_store_uint(&reader->n_readers, 0);  in ck_brlock_read_trylock()
262 		if (++steps >= factor)  in ck_brlock_read_trylock()
275 	ck_pr_store_uint(&reader->n_readers, reader->n_readers - 1);  in ck_brlock_read_unlock()