Current Path : /sys/dev/filemon/ |
FreeBSD hs32.drive.ne.jp 9.1-RELEASE FreeBSD 9.1-RELEASE #1: Wed Jan 14 12:18:08 JST 2015 root@hs32.drive.ne.jp:/sys/amd64/compile/hs32 amd64 |
Current File : //sys/dev/filemon/filemon_lock.c |
/*- * 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: release/9.1.0/sys/dev/filemon/filemon_lock.c 236592 2012-06-04 22:54:19Z obrien $"); 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); }