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/*-
* Copyright (c) 2009-2011, Juniper Networks, Inc.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY JUNIPER NETWORKS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL JUNIPER NETWORKS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
static void
filemon_filemon_lock(struct filemon *filemon)
{
mtx_lock(&filemon->mtx);
while (filemon->locker != NULL && filemon->locker != curthread)
cv_wait(&filemon->cv, &filemon->mtx);
filemon->locker = curthread;
mtx_unlock(&filemon->mtx);
}
static void
filemon_filemon_unlock(struct filemon *filemon)
{
mtx_lock(&filemon->mtx);
if (filemon->locker == curthread)
filemon->locker = NULL;
/* Wake up threads waiting. */
cv_broadcast(&filemon->cv);
mtx_unlock(&filemon->mtx);
}
static void
filemon_lock_read(void)
{
mtx_lock(&access_mtx);
while (access_owner != NULL || access_requester != NULL)
cv_wait(&access_cv, &access_mtx);
n_readers++;
/* Wake up threads waiting. */
cv_broadcast(&access_cv);
mtx_unlock(&access_mtx);
}
static void
filemon_unlock_read(void)
{
mtx_lock(&access_mtx);
if (n_readers > 0)
n_readers--;
/* Wake up a thread waiting. */
cv_broadcast(&access_cv);
mtx_unlock(&access_mtx);
}
static void
filemon_lock_write(void)
{
mtx_lock(&access_mtx);
while (access_owner != curthread) {
if (access_owner == NULL &&
(access_requester == NULL ||
access_requester == curthread)) {
access_owner = curthread;
access_requester = NULL;
} else {
if (access_requester == NULL)
access_requester = curthread;
cv_wait(&access_cv, &access_mtx);
}
}
mtx_unlock(&access_mtx);
}
static void
filemon_unlock_write(void)
{
mtx_lock(&access_mtx);
/* Sanity check that the current thread actually has the write lock. */
if (access_owner == curthread)
access_owner = NULL;
/* Wake up a thread waiting. */
cv_broadcast(&access_cv);
mtx_unlock(&access_mtx);
}
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