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