FreeBSD/Linux Kernel Cross Reference
sys/sys/_rmlock.h

     /*-
      * SPDX-License-Identifier: BSD-3-Clause
      *
      * Copyright (c) 2007 Stephan Uphoff <ups@FreeBSD.org>
      * 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.
     * 3. Neither the name of the author nor the names of any co-contributors
     *    may be used to endorse or promote products derived from this software
     *    without specific prior written permission.
     *
     * THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 THE AUTHOR 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.
     *
     * $FreeBSD: releng/12.0/sys/sys/_rmlock.h 326023 2017-11-20 19:43:44Z pfg $
     */
    
    #ifndef _SYS__RMLOCK_H_
    #define _SYS__RMLOCK_H_
    
    /*
     * Mostly reader/occasional writer lock.
     */
    
    LIST_HEAD(rmpriolist,rm_priotracker);
    
    struct rm_queue {
            struct rm_queue *volatile rmq_next;
            struct rm_queue *volatile rmq_prev;
    };
    
    struct rmlock {
            struct lock_object lock_object;
            volatile cpuset_t rm_writecpus;
            LIST_HEAD(,rm_priotracker) rm_activeReaders;
            union {
                    struct lock_object _rm_wlock_object;
                    struct mtx _rm_lock_mtx;
                    struct sx _rm_lock_sx;
            } _rm_lock;
    };
    
    #define rm_wlock_object _rm_lock._rm_wlock_object
    #define rm_lock_mtx     _rm_lock._rm_lock_mtx
    #define rm_lock_sx      _rm_lock._rm_lock_sx
    
    struct rm_priotracker {
            struct rm_queue rmp_cpuQueue; /* Must be first */
            struct rmlock *rmp_rmlock;
            struct thread *rmp_thread;
            int rmp_flags;
            LIST_ENTRY(rm_priotracker) rmp_qentry;
    };
    
    #endif /* !_SYS__RMLOCK_H_ */

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