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Annotation of OSKit-Mach/kern/lock.h, revision 1.1

1.1     ! root        1: /* 
        !             2:  * Mach Operating System
        !             3:  * Copyright (c) 1993-1987 Carnegie Mellon University
        !             4:  * All Rights Reserved.
        !             5:  * 
        !             6:  * Permission to use, copy, modify and distribute this software and its
        !             7:  * documentation is hereby granted, provided that both the copyright
        !             8:  * notice and this permission notice appear in all copies of the
        !             9:  * software, derivative works or modified versions, and any portions
        !            10:  * thereof, and that both notices appear in supporting documentation.
        !            11:  * 
        !            12:  * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
        !            13:  * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
        !            14:  * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
        !            15:  * 
        !            16:  * Carnegie Mellon requests users of this software to return to
        !            17:  * 
        !            18:  *  Software Distribution Coordinator  or  [email protected]
        !            19:  *  School of Computer Science
        !            20:  *  Carnegie Mellon University
        !            21:  *  Pittsburgh PA 15213-3890
        !            22:  * 
        !            23:  * any improvements or extensions that they make and grant Carnegie Mellon
        !            24:  * the rights to redistribute these changes.
        !            25:  */
        !            26: /*
        !            27:  *     File:   kern/lock.h
        !            28:  *     Author: Avadis Tevanian, Jr., Michael Wayne Young
        !            29:  *     Date:   1985
        !            30:  *
        !            31:  *     Locking primitives definitions
        !            32:  */
        !            33: 
        !            34: #ifndef        _KERN_LOCK_H_
        !            35: #define        _KERN_LOCK_H_
        !            36: 
        !            37: #include <cpus.h>
        !            38: #include <mach_ldebug.h>
        !            39: 
        !            40: #include <mach/boolean.h>
        !            41: #include <mach/machine/vm_types.h>
        !            42: 
        !            43: #if NCPUS > 1
        !            44: #include <machine/lock.h>/*XXX*/
        !            45: #endif
        !            46: 
        !            47: #define MACH_SLOCKS    ((NCPUS > 1) || MACH_LDEBUG)
        !            48: 
        !            49: /*
        !            50:  *     A simple spin lock.
        !            51:  */
        !            52: 
        !            53: struct slock {
        !            54:        volatile natural_t lock_data;   /* in general 1 bit is sufficient */
        !            55: };
        !            56: 
        !            57: typedef struct slock   simple_lock_data_t;
        !            58: typedef struct slock   *simple_lock_t;
        !            59: 
        !            60: #if    MACH_SLOCKS
        !            61: /*
        !            62:  *     Use the locks.
        !            63:  */
        !            64: 
        !            65: #define        decl_simple_lock_data(class,name) \
        !            66: class  simple_lock_data_t      name;
        !            67: 
        !            68: #define        simple_lock_addr(lock)  (&(lock))
        !            69: 
        !            70: #if    (NCPUS > 1)
        !            71: 
        !            72: /*
        !            73:  *     The single-CPU debugging routines are not valid
        !            74:  *     on a multiprocessor.
        !            75:  */
        !            76: #define        simple_lock_taken(lock)         (1)     /* always succeeds */
        !            77: #define check_simple_locks()
        !            78: 
        !            79: #else  /* NCPUS > 1 */
        !            80: /*
        !            81:  *     Use our single-CPU locking test routines.
        !            82:  */
        !            83: 
        !            84: extern void            simple_lock_init(simple_lock_t);
        !            85: extern void            simple_lock(simple_lock_t);
        !            86: extern void            simple_unlock(simple_lock_t);
        !            87: extern boolean_t       simple_lock_try(simple_lock_t);
        !            88: 
        !            89: #define simple_lock_pause()
        !            90: #define simple_lock_taken(lock)                ((lock)->lock_data)
        !            91: 
        !            92: extern void            check_simple_locks(void);
        !            93: 
        !            94: #endif /* NCPUS > 1 */
        !            95: 
        !            96: #else  /* MACH_SLOCKS */
        !            97: /*
        !            98:  * Do not allocate storage for locks if not needed.
        !            99:  */
        !           100: #define        decl_simple_lock_data(class,name)
        !           101: #define        simple_lock_addr(lock)          ((simple_lock_t)0)
        !           102: 
        !           103: /*
        !           104:  *     No multiprocessor locking is necessary.
        !           105:  */
        !           106: #define simple_lock_init(l)
        !           107: #define simple_lock(l)
        !           108: #define simple_unlock(l)
        !           109: #define simple_lock_try(l)     (TRUE)  /* always succeeds */
        !           110: #define simple_lock_taken(l)   (1)     /* always succeeds */
        !           111: #define check_simple_locks()
        !           112: #define simple_lock_pause()
        !           113: 
        !           114: #endif /* MACH_SLOCKS */
        !           115: 
        !           116: 
        !           117: #define decl_mutex_data(class,name)    decl_simple_lock_data(class,name)
        !           118: #define        mutex_try(l)                    simple_lock_try(l)
        !           119: #define        mutex_lock(l)                   simple_lock(l)
        !           120: #define        mutex_unlock(l)                 simple_unlock(l)
        !           121: #define        mutex_init(l)                   simple_lock_init(l)
        !           122: 
        !           123: 
        !           124: /*
        !           125:  *     The general lock structure.  Provides for multiple readers,
        !           126:  *     upgrading from read to write, and sleeping until the lock
        !           127:  *     can be gained.
        !           128:  *
        !           129:  *     On some architectures, assembly language code in the 'inline'
        !           130:  *     program fiddles the lock structures.  It must be changed in
        !           131:  *     concert with the structure layout.
        !           132:  *
        !           133:  *     Only the "interlock" field is used for hardware exclusion;
        !           134:  *     other fields are modified with normal instructions after
        !           135:  *     acquiring the interlock bit.
        !           136:  */
        !           137: struct lock {
        !           138:        struct thread   *thread;        /* Thread that has lock, if
        !           139:                                           recursive locking allowed */
        !           140:        unsigned int    read_count:16,  /* Number of accepted readers */
        !           141:        /* boolean_t */ want_upgrade:1, /* Read-to-write upgrade waiting */
        !           142:        /* boolean_t */ want_write:1,   /* Writer is waiting, or
        !           143:                                           locked for write */
        !           144:        /* boolean_t */ waiting:1,      /* Someone is sleeping on lock */
        !           145:        /* boolean_t */ can_sleep:1,    /* Can attempts to lock go to sleep? */
        !           146:                        recursion_depth:12, /* Depth of recursion */
        !           147:                        :0; 
        !           148:        decl_simple_lock_data(,interlock)
        !           149:                                        /* Hardware interlock field.
        !           150:                                           Last in the structure so that
        !           151:                                           field offsets are the same whether
        !           152:                                           or not it is present. */
        !           153: };
        !           154: 
        !           155: typedef struct lock    lock_data_t;
        !           156: typedef struct lock    *lock_t;
        !           157: 
        !           158: /* Sleep locks must work even if no multiprocessing */
        !           159: 
        !           160: extern void            lock_init(lock_t, boolean_t);
        !           161: extern void            lock_sleepable(lock_t, boolean_t);
        !           162: extern void            lock_write(lock_t);
        !           163: extern void            lock_read(lock_t);
        !           164: extern void            lock_done(lock_t);
        !           165: extern boolean_t       lock_read_to_write(lock_t);
        !           166: extern void            lock_write_to_read(lock_t);
        !           167: extern boolean_t       lock_try_write(lock_t);
        !           168: extern boolean_t       lock_try_read(lock_t);
        !           169: extern boolean_t       lock_try_read_to_write(lock_t);
        !           170: 
        !           171: #define        lock_read_done(l)       lock_done(l)
        !           172: #define        lock_write_done(l)      lock_done(l)
        !           173: 
        !           174: extern void            lock_set_recursive(lock_t);
        !           175: extern void            lock_clear_recursive(lock_t);
        !           176: 
        !           177: #endif /* _KERN_LOCK_H_ */

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