sortix--sortix/libc/pthread/pthread_rwlock_unlock.c

/*
 * Copyright (c) 2013 Jonas 'Sortie' Termansen.
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 *
 * pthread/pthread_rwlock_unlock.c
 * Releases hold of a read-write lock.
 */

#include <pthread.h>

int pthread_rwlock_unlock(pthread_rwlock_t* rwlock)
{
	pthread_mutex_lock(&rwlock->request_mutex);
	if ( rwlock->num_writers )
	{
		rwlock->num_writers = 0;
		if ( rwlock->pending_writers )
			pthread_cond_signal(&rwlock->writer_condition);
		else
			pthread_cond_broadcast(&rwlock->reader_condition);
	}
	else
	{
		if ( --rwlock->num_readers == 0 && rwlock->pending_writers )
			pthread_cond_signal(&rwlock->writer_condition);
	}
	pthread_mutex_unlock(&rwlock->request_mutex);
	return 0;
}