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118 lines
4.5 KiB
C
118 lines
4.5 KiB
C
/*
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* Copyright (c) 1991, 1993
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* The Regents of the University of California. All rights reserved.
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*
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* This code is derived from software contributed to Berkeley by
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* The Mach Operating System project at Carnegie-Mellon University.
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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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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the University of
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* California, Berkeley and its contributors.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 THE REGENTS 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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* from: @(#)lock.h 8.1 (Berkeley) 6/11/93
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*
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*
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* Copyright (c) 1987, 1990 Carnegie-Mellon University.
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* All rights reserved.
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*
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* Authors: Avadis Tevanian, Jr., Michael Wayne Young
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*
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* Permission to use, copy, modify and distribute this software and
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* its documentation is hereby granted, provided that both the copyright
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* notice and this permission notice appear in all copies of the
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* software, derivative works or modified versions, and any portions
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* thereof, and that both notices appear in supporting documentation.
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*
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* CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
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* CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND
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* FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
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*
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* Carnegie Mellon requests users of this software to return to
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*
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* Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU
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* School of Computer Science
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* Carnegie Mellon University
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* Pittsburgh PA 15213-3890
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*
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* any improvements or extensions that they make and grant Carnegie the
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* rights to redistribute these changes.
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*
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* $Id$
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*/
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/*
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* Locking primitives definitions
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*/
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#ifndef _LOCK_H_
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#define _LOCK_H_
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/*
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* The general lock structure. Provides for multiple readers,
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* upgrading from read to write, and sleeping until the lock
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* can be gained.
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*/
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struct lock {
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/*
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* Only the "interlock" field is used for hardware exclusion; other
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* fields are modified with normal instructions after acquiring the
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* interlock bit.
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*/
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boolean_t want_write; /* Writer is waiting, or locked for write */
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boolean_t want_upgrade; /* Read-to-write upgrade waiting */
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boolean_t waiting; /* Someone is sleeping on lock */
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boolean_t can_sleep; /* Can attempts to lock go to sleep */
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int read_count; /* Number of accepted readers */
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struct proc *proc; /* If recursive locking, process that has lock */
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int recursion_depth; /* Depth of recursion */
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};
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typedef struct lock lock_data_t;
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typedef struct lock *lock_t;
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/* Sleep locks must work even if no multiprocessing. */
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#define lock_read_done(l) lock_done(l)
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#define lock_write_done(l) lock_done(l)
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#ifdef KERNEL
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void lock_clear_recursive __P((lock_t));
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void lock_done __P((lock_t));
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void lock_init __P((lock_t, boolean_t));
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void lock_read __P((lock_t));
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boolean_t lock_read_to_write __P((lock_t));
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void lock_set_recursive __P((lock_t));
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void lock_sleepable __P((lock_t, boolean_t));
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boolean_t lock_try_read __P((lock_t));
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boolean_t lock_try_read_to_write __P((lock_t));
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boolean_t lock_try_write __P((lock_t));
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void lock_write __P((lock_t));
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void lock_write_to_read __P((lock_t));
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#endif
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#endif /* !_LOCK_H_ */
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