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

     /*-
      * Copyright (c) 2009 Konstantin Belousov <kib@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 unmodified, 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 THE AUTHOR ``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 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/9.2/sys/sys/rangelock.h 239835 2012-08-29 15:13:13Z kib $
     */
    
    #ifndef _SYS_RANGELOCK_H
    #define _SYS_RANGELOCK_H
    
    #include <sys/queue.h>
    
    #define RL_LOCK_READ            0x0001
    #define RL_LOCK_WRITE           0x0002
    #define RL_LOCK_TYPE_MASK       0x0003
    #define RL_LOCK_GRANTED         0x0004
    
    struct rl_q_entry;
    
    /*
     * The structure representing the range lock.  Caller may request
     * read or write access to the range of bytes. Access is granted if
     * all existing lock owners are compatible with the request. Two lock
     * owners are compatible if their ranges do not overlap, or both
     * owners are for read.
     *
     * Access to the structure itself is synchronized with the externally
     * supplied mutex.
     *
     * rl_waiters is the queue of lock requests in the order of arrival.
     * rl_currdep is the first lock request that cannot be granted now due
     * to the preceding requests conflicting with it.
     */
    struct rangelock {
            TAILQ_HEAD(, rl_q_entry) rl_waiters;
            struct rl_q_entry       *rl_currdep;
    };
    
    #ifdef _KERNEL
    
    struct mtx;
    
    void     rangelock_init(struct rangelock *lock);
    void     rangelock_destroy(struct rangelock *lock);
    void     rangelock_unlock(struct rangelock *lock, void *cookie,
                struct mtx *ilk);
    void    *rangelock_unlock_range(struct rangelock *lock, void *cookie,
                off_t start, off_t end, struct mtx *ilk);
    void    *rangelock_rlock(struct rangelock *lock, off_t start, off_t end,
                struct mtx *ilk);
    void    *rangelock_wlock(struct rangelock *lock, off_t start, off_t end,
                struct mtx *ilk);
    void     rlqentry_free(struct rl_q_entry *rlqe);
    
    #endif  /* _KERNEL */
    
    #endif  /* _SYS_RANGELOCK_H */

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