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Annotation of kernel/kern/lock.h, revision 1.1

1.1     ! root        1: /*
        !             2:  * Copyright (c) 1999 Apple Computer, Inc. All rights reserved.
        !             3:  *
        !             4:  * @APPLE_LICENSE_HEADER_START@
        !             5:  * 
        !             6:  * Portions Copyright (c) 1999 Apple Computer, Inc.  All Rights
        !             7:  * Reserved.  This file contains Original Code and/or Modifications of
        !             8:  * Original Code as defined in and that are subject to the Apple Public
        !             9:  * Source License Version 1.1 (the "License").  You may not use this file
        !            10:  * except in compliance with the License.  Please obtain a copy of the
        !            11:  * License at http://www.apple.com/publicsource and read it before using
        !            12:  * this file.
        !            13:  * 
        !            14:  * The Original Code and all software distributed under the License are
        !            15:  * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
        !            16:  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
        !            17:  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
        !            18:  * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
        !            19:  * License for the specific language governing rights and limitations
        !            20:  * under the License.
        !            21:  * 
        !            22:  * @APPLE_LICENSE_HEADER_END@
        !            23:  */
        !            24: 
        !            25: /* 
        !            26:  * Mach Operating System
        !            27:  * Copyright (c) 1993-1987 Carnegie Mellon University
        !            28:  * All Rights Reserved.
        !            29:  * 
        !            30:  * Permission to use, copy, modify and distribute this software and its
        !            31:  * documentation is hereby granted, provided that both the copyright
        !            32:  * notice and this permission notice appear in all copies of the
        !            33:  * software, derivative works or modified versions, and any portions
        !            34:  * thereof, and that both notices appear in supporting documentation.
        !            35:  * 
        !            36:  * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
        !            37:  * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
        !            38:  * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
        !            39:  * 
        !            40:  * Carnegie Mellon requests users of this software to return to
        !            41:  * 
        !            42:  *  Software Distribution Coordinator  or  [email protected]
        !            43:  *  School of Computer Science
        !            44:  *  Carnegie Mellon University
        !            45:  *  Pittsburgh PA 15213-3890
        !            46:  * 
        !            47:  * any improvements or extensions that they make and grant Carnegie Mellon
        !            48:  * the rights to redistribute these changes.
        !            49:  */
        !            50: /*
        !            51:  *     File:   kern/lock.h
        !            52:  *     Author: Avadis Tevanian, Jr., Michael Wayne Young
        !            53:  *     Date:   1985
        !            54:  *
        !            55:  *     Locking primitives definitions
        !            56:  */
        !            57: 
        !            58: #ifndef        _KERN_LOCK_H_
        !            59: #define        _KERN_LOCK_H_
        !            60: 
        !            61: #import <mach/features.h>
        !            62: 
        !            63: #include <mach/boolean.h>
        !            64: #include <mach/machine/vm_types.h>
        !            65: 
        !            66: #define MACH_SLOCKS    ((NCPUS > 1) || MACH_LDEBUG || DRIVERKIT)
        !            67: 
        !            68: #ifndef        _MACHINE_SIMPLE_LOCK_DATA_
        !            69: /*
        !            70:  *     A simple spin lock.
        !            71:  */
        !            72: 
        !            73: struct slock {
        !            74:        volatile natural_t lock_data;   /* in general 1 bit is sufficient */
        !            75: };
        !            76: 
        !            77: typedef struct slock   simple_lock_data_t;
        !            78: typedef struct slock   *simple_lock_t;
        !            79: #endif /* _MACHINE_SIMPLE_LOCK_DATA_ */
        !            80: 
        !            81: #if    MACH_SLOCKS
        !            82: /*
        !            83:  *     Use the locks.
        !            84:  */
        !            85: 
        !            86: #define        decl_simple_lock_data(class,name) \
        !            87: class  simple_lock_data_t      name;
        !            88: 
        !            89: #define        simple_lock_addr(lock)  (&(lock))
        !            90: 
        !            91: #else  /* MACH_SLOCKS */
        !            92: /*
        !            93:  * Do not allocate storage for locks if not needed.
        !            94:  */
        !            95: #define        decl_simple_lock_data(class,name)
        !            96: #define        simple_lock_addr(lock)          ((simple_lock_t)0)
        !            97: 
        !            98: /*
        !            99:  *     No multiprocessor locking is necessary.
        !           100:  */
        !           101: #define simple_lock_init(l)
        !           102: #define simple_lock(l)
        !           103: #define simple_unlock(l)
        !           104: #define simple_lock_try(l)     (TRUE)  /* always succeeds */
        !           105: #define simple_lock_taken(l)   (1)     /* always succeeds */
        !           106: #define check_simple_locks()
        !           107: #define simple_lock_pause()
        !           108: 
        !           109: #endif /* MACH_SLOCKS */
        !           110: 
        !           111: extern simple_lock_t   simple_lock_alloc(void);
        !           112: extern void            simple_lock_free(simple_lock_t);
        !           113: 
        !           114: /*
        !           115:  *     The general lock structure.  Provides for multiple readers,
        !           116:  *     upgrading from read to write, and sleeping until the lock
        !           117:  *     can be gained.
        !           118:  *
        !           119:  *     On some architectures, assembly language code in the 'inline'
        !           120:  *     program fiddles the lock structures.  It must be changed in
        !           121:  *     concert with the structure layout.
        !           122:  *
        !           123:  *     Only the "interlock" field is used for hardware exclusion;
        !           124:  *     other fields are modified with normal instructions after
        !           125:  *     acquiring the interlock bit.
        !           126:  */
        !           127: struct lock {
        !           128:        struct thread   *thread;        /* Thread that has lock, if
        !           129:                                           recursive locking allowed */
        !           130:        unsigned int    read_count:16,  /* Number of accepted readers */
        !           131:        /* boolean_t */ want_upgrade:1, /* Read-to-write upgrade waiting */
        !           132:        /* boolean_t */ want_write:1,   /* Writer is waiting, or
        !           133:                                           locked for write */
        !           134:        /* boolean_t */ waiting:1,      /* Someone is sleeping on lock */
        !           135:        /* boolean_t */ can_sleep:1,    /* Can attempts to lock go to sleep? */
        !           136:                        recursion_depth:12, /* Depth of recursion */
        !           137:                        :0; 
        !           138:        decl_simple_lock_data(,interlock)
        !           139:                                        /* Hardware interlock field.
        !           140:                                           Last in the structure so that
        !           141:                                           field offsets are the same whether
        !           142:                                           or not it is present. */
        !           143: };
        !           144: 
        !           145: typedef struct lock    lock_data_t;
        !           146: typedef struct lock    *lock_t;
        !           147: 
        !           148: /* Sleep locks must work even if no multiprocessing */
        !           149: 
        !           150: extern void            lock_init(lock_t, boolean_t);
        !           151: extern void            lock_sleepable(lock_t, boolean_t);
        !           152: extern void            lock_write(lock_t);
        !           153: extern void            lock_read(lock_t);
        !           154: extern void            lock_done(lock_t);
        !           155: extern boolean_t       lock_read_to_write(lock_t);
        !           156: extern void            lock_write_to_read(lock_t);
        !           157: extern boolean_t       lock_try_write(lock_t);
        !           158: extern boolean_t       lock_try_read(lock_t);
        !           159: extern boolean_t       lock_try_read_to_write(lock_t);
        !           160: 
        !           161: #define        lock_read_done(l)       lock_done(l)
        !           162: #define        lock_write_done(l)      lock_done(l)
        !           163: 
        !           164: extern void            lock_set_recursive(lock_t);
        !           165: extern void            lock_clear_recursive(lock_t);
        !           166: 
        !           167: extern lock_t          lock_alloc(void);
        !           168: extern void            lock_free(lock_t);
        !           169: 
        !           170: #endif /* _KERN_LOCK_H_ */

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