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/*
* Mach Operating System
* Copyright (c) 1993-1987 Carnegie Mellon University
* All Rights Reserved.
*
* Permission to use, copy, modify and distribute this software and its
* documentation is hereby granted, provided that both the copyright
* notice and this permission notice appear in all copies of the
* software, derivative works or modified versions, and any portions
* thereof, and that both notices appear in supporting documentation.
*
* CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
* CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
* ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
*
* Carnegie Mellon requests users of this software to return to
*
* Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU
* School of Computer Science
* Carnegie Mellon University
* Pittsburgh PA 15213-3890
*
* any improvements or extensions that they make and grant Carnegie Mellon
* the rights to redistribute these changes.
*/
/*
* File: kern/lock.h
* Author: Avadis Tevanian, Jr., Michael Wayne Young
* Date: 1985
*
* Locking primitives definitions
*/
#ifndef _KERN_LOCK_H_
#define _KERN_LOCK_H_
#include <mach/boolean.h>
#include <mach/machine/vm_types.h>
#if NCPUS > 1
#include <machine/lock.h>/*XXX*/
#endif
#define MACH_SLOCKS ((NCPUS > 1) || MACH_LDEBUG)
/*
* A simple spin lock.
*/
struct slock {
volatile natural_t lock_data; /* in general 1 bit is sufficient */
struct {} is_a_simple_lock;
};
/*
* Used by macros to assert that the given argument is a simple
* lock.
*/
#define simple_lock_assert(l) (void) &(l)->is_a_simple_lock
typedef struct slock simple_lock_data_t;
typedef struct slock *simple_lock_t;
#if MACH_SLOCKS
/*
* Use the locks.
*/
#define decl_simple_lock_data(class,name) \
class simple_lock_data_t name;
#define simple_lock_addr(lock) (simple_lock_assert(&(lock)), \
&(lock))
#if (NCPUS > 1)
/*
* The single-CPU debugging routines are not valid
* on a multiprocessor.
*/
#define simple_lock_taken(lock) (simple_lock_assert(lock), \
1) /* always succeeds */
#define check_simple_locks()
#define check_simple_locks_enable()
#define check_simple_locks_disable()
#else /* NCPUS > 1 */
/*
* Use our single-CPU locking test routines.
*/
extern void simple_lock_init(simple_lock_t);
extern void _simple_lock(simple_lock_t,
const char *, const char *);
extern void simple_unlock(simple_lock_t);
extern boolean_t _simple_lock_try(simple_lock_t,
const char *, const char *);
/* We provide simple_lock and simple_lock_try so that we can save the
location. */
#define XSTR(x) #x
#define STR(x) XSTR(x)
#define LOCATION __FILE__ ":" STR(__LINE__)
#define simple_lock(lock) _simple_lock((lock), #lock, LOCATION)
#define simple_lock_try(lock) _simple_lock_try((lock), #lock, LOCATION)
#define simple_lock_pause()
#define simple_lock_taken(lock) (simple_lock_assert(lock), \
(lock)->lock_data)
extern void check_simple_locks(void);
extern void check_simple_locks_enable(void);
extern void check_simple_locks_disable(void);
#endif /* NCPUS > 1 */
#else /* MACH_SLOCKS */
/*
* Do not allocate storage for locks if not needed.
*/
struct simple_lock_data_empty { struct {} is_a_simple_lock; };
#define decl_simple_lock_data(class,name) \
class struct simple_lock_data_empty name;
#define simple_lock_addr(lock) (simple_lock_assert(&(lock)), \
(simple_lock_t)0)
/*
* No multiprocessor locking is necessary.
*/
#define simple_lock_init(l) simple_lock_assert(l)
#define simple_lock(l) simple_lock_assert(l)
#define simple_unlock(l) simple_lock_assert(l)
#define simple_lock_try(l) (simple_lock_assert(l), \
TRUE) /* always succeeds */
#define simple_lock_taken(l) (simple_lock_assert(l), \
1) /* always succeeds */
#define check_simple_locks()
#define check_simple_locks_enable()
#define check_simple_locks_disable()
#define simple_lock_pause()
#endif /* MACH_SLOCKS */
#define decl_mutex_data(class,name) decl_simple_lock_data(class,name)
#define mutex_try(l) simple_lock_try(l)
#define mutex_lock(l) simple_lock(l)
#define mutex_unlock(l) simple_unlock(l)
#define mutex_init(l) simple_lock_init(l)
/*
* The general lock structure. Provides for multiple readers,
* upgrading from read to write, and sleeping until the lock
* can be gained.
*
* On some architectures, assembly language code in the 'inline'
* program fiddles the lock structures. It must be changed in
* concert with the structure layout.
*
* Only the "interlock" field is used for hardware exclusion;
* other fields are modified with normal instructions after
* acquiring the interlock bit.
*/
struct lock {
struct thread *thread; /* Thread that has lock, if
recursive locking allowed */
unsigned int read_count:16, /* Number of accepted readers */
/* boolean_t */ want_upgrade:1, /* Read-to-write upgrade waiting */
/* boolean_t */ want_write:1, /* Writer is waiting, or
locked for write */
/* boolean_t */ waiting:1, /* Someone is sleeping on lock */
/* boolean_t */ can_sleep:1, /* Can attempts to lock go to sleep? */
recursion_depth:12, /* Depth of recursion */
:0;
#if MACH_LDEBUG
struct thread *writer;
#endif /* MACH_LDEBUG */
decl_simple_lock_data(,interlock)
/* Hardware interlock field.
Last in the structure so that
field offsets are the same whether
or not it is present. */
};
typedef struct lock lock_data_t;
typedef struct lock *lock_t;
/* Sleep locks must work even if no multiprocessing */
extern void lock_init(lock_t, boolean_t);
extern void lock_sleepable(lock_t, boolean_t);
extern void lock_write(lock_t);
extern void lock_read(lock_t);
extern void lock_done(lock_t);
extern boolean_t lock_read_to_write(lock_t);
extern void lock_write_to_read(lock_t);
extern boolean_t lock_try_write(lock_t);
extern boolean_t lock_try_read(lock_t);
extern boolean_t lock_try_read_to_write(lock_t);
#define lock_read_done(l) lock_done(l)
#define lock_write_done(l) lock_done(l)
#define lock_taken(l) ((l)->want_write || (l)->read_count)
extern void lock_set_recursive(lock_t);
extern void lock_clear_recursive(lock_t);
/* Lock debugging support. */
#if ! MACH_LDEBUG
#define have_read_lock(l) 1
#define have_write_lock(l) 1
#define lock_write_surrender(l)
#define lock_write_steal(l)
#else /* MACH_LDEBUG */
/* XXX: We don't keep track of readers, so this is an approximation. */
#define have_read_lock(l) ((l)->read_count > 0)
#define have_write_lock(l) ((l)->writer == current_thread())
#define THREAD_SURRENDERED ((thread_t) ~0U)
#define lock_write_surrender(l) ({ \
assert(have_write_lock(l)); \
(l)->writer = THREAD_SURRENDERED; \
})
#define lock_write_steal(l) ({ \
assert((l)->writer == THREAD_SURRENDERED); \
(l)->writer = current_thread(); \
})
#endif /* MACH_LDEBUG */
#define have_lock(l) (have_read_lock(l) || have_write_lock(l))
void db_show_all_slocks(void);
#endif /* _KERN_LOCK_H_ */
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