168 lines
3.9 KiB
C
168 lines
3.9 KiB
C
/*
|
|
* include/asm-ppc64/rwsem.h: R/W semaphores for PPC using the stuff
|
|
* in lib/rwsem.c. Adapted largely from include/asm-i386/rwsem.h
|
|
* by Paul Mackerras <paulus@samba.org>.
|
|
*
|
|
* This program is free software; you can redistribute it and/or
|
|
* modify it under the terms of the GNU General Public License
|
|
* as published by the Free Software Foundation; either version
|
|
* 2 of the License, or (at your option) any later version.
|
|
*/
|
|
|
|
#ifndef _PPC64_RWSEM_H
|
|
#define _PPC64_RWSEM_H
|
|
|
|
#ifdef __KERNEL__
|
|
#include <linux/list.h>
|
|
#include <linux/spinlock.h>
|
|
#include <asm/atomic.h>
|
|
#include <asm/system.h>
|
|
|
|
/*
|
|
* the semaphore definition
|
|
*/
|
|
struct rw_semaphore {
|
|
/* XXX this should be able to be an atomic_t -- paulus */
|
|
signed int count;
|
|
#define RWSEM_UNLOCKED_VALUE 0x00000000
|
|
#define RWSEM_ACTIVE_BIAS 0x00000001
|
|
#define RWSEM_ACTIVE_MASK 0x0000ffff
|
|
#define RWSEM_WAITING_BIAS (-0x00010000)
|
|
#define RWSEM_ACTIVE_READ_BIAS RWSEM_ACTIVE_BIAS
|
|
#define RWSEM_ACTIVE_WRITE_BIAS (RWSEM_WAITING_BIAS + RWSEM_ACTIVE_BIAS)
|
|
spinlock_t wait_lock;
|
|
struct list_head wait_list;
|
|
#if RWSEM_DEBUG
|
|
int debug;
|
|
#endif
|
|
};
|
|
|
|
/*
|
|
* initialisation
|
|
*/
|
|
#if RWSEM_DEBUG
|
|
#define __RWSEM_DEBUG_INIT , 0
|
|
#else
|
|
#define __RWSEM_DEBUG_INIT /* */
|
|
#endif
|
|
|
|
#define __RWSEM_INITIALIZER(name) \
|
|
{ RWSEM_UNLOCKED_VALUE, SPIN_LOCK_UNLOCKED, \
|
|
LIST_HEAD_INIT((name).wait_list) \
|
|
__RWSEM_DEBUG_INIT }
|
|
|
|
#define DECLARE_RWSEM(name) \
|
|
struct rw_semaphore name = __RWSEM_INITIALIZER(name)
|
|
|
|
extern struct rw_semaphore *rwsem_down_read_failed(struct rw_semaphore *sem);
|
|
extern struct rw_semaphore *rwsem_down_write_failed(struct rw_semaphore *sem);
|
|
extern struct rw_semaphore *rwsem_wake(struct rw_semaphore *sem);
|
|
extern struct rw_semaphore *rwsem_downgrade_wake(struct rw_semaphore *sem);
|
|
|
|
static inline void init_rwsem(struct rw_semaphore *sem)
|
|
{
|
|
sem->count = RWSEM_UNLOCKED_VALUE;
|
|
spin_lock_init(&sem->wait_lock);
|
|
INIT_LIST_HEAD(&sem->wait_list);
|
|
#if RWSEM_DEBUG
|
|
sem->debug = 0;
|
|
#endif
|
|
}
|
|
|
|
/*
|
|
* lock for reading
|
|
*/
|
|
static inline void __down_read(struct rw_semaphore *sem)
|
|
{
|
|
if (unlikely(atomic_inc_return((atomic_t *)(&sem->count)) <= 0))
|
|
rwsem_down_read_failed(sem);
|
|
}
|
|
|
|
static inline int __down_read_trylock(struct rw_semaphore *sem)
|
|
{
|
|
int tmp;
|
|
|
|
while ((tmp = sem->count) >= 0) {
|
|
if (tmp == cmpxchg(&sem->count, tmp,
|
|
tmp + RWSEM_ACTIVE_READ_BIAS)) {
|
|
return 1;
|
|
}
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* lock for writing
|
|
*/
|
|
static inline void __down_write(struct rw_semaphore *sem)
|
|
{
|
|
int tmp;
|
|
|
|
tmp = atomic_add_return(RWSEM_ACTIVE_WRITE_BIAS,
|
|
(atomic_t *)(&sem->count));
|
|
if (unlikely(tmp != RWSEM_ACTIVE_WRITE_BIAS))
|
|
rwsem_down_write_failed(sem);
|
|
}
|
|
|
|
static inline int __down_write_trylock(struct rw_semaphore *sem)
|
|
{
|
|
int tmp;
|
|
|
|
tmp = cmpxchg(&sem->count, RWSEM_UNLOCKED_VALUE,
|
|
RWSEM_ACTIVE_WRITE_BIAS);
|
|
return tmp == RWSEM_UNLOCKED_VALUE;
|
|
}
|
|
|
|
/*
|
|
* unlock after reading
|
|
*/
|
|
static inline void __up_read(struct rw_semaphore *sem)
|
|
{
|
|
int tmp;
|
|
|
|
tmp = atomic_dec_return((atomic_t *)(&sem->count));
|
|
if (unlikely(tmp < -1 && (tmp & RWSEM_ACTIVE_MASK) == 0))
|
|
rwsem_wake(sem);
|
|
}
|
|
|
|
/*
|
|
* unlock after writing
|
|
*/
|
|
static inline void __up_write(struct rw_semaphore *sem)
|
|
{
|
|
if (unlikely(atomic_sub_return(RWSEM_ACTIVE_WRITE_BIAS,
|
|
(atomic_t *)(&sem->count)) < 0))
|
|
rwsem_wake(sem);
|
|
}
|
|
|
|
/*
|
|
* implement atomic add functionality
|
|
*/
|
|
static inline void rwsem_atomic_add(int delta, struct rw_semaphore *sem)
|
|
{
|
|
atomic_add(delta, (atomic_t *)(&sem->count));
|
|
}
|
|
|
|
/*
|
|
* downgrade write lock to read lock
|
|
*/
|
|
static inline void __downgrade_write(struct rw_semaphore *sem)
|
|
{
|
|
int tmp;
|
|
|
|
tmp = atomic_add_return(-RWSEM_WAITING_BIAS, (atomic_t *)(&sem->count));
|
|
if (tmp < 0)
|
|
rwsem_downgrade_wake(sem);
|
|
}
|
|
|
|
/*
|
|
* implement exchange and add functionality
|
|
*/
|
|
static inline int rwsem_atomic_update(int delta, struct rw_semaphore *sem)
|
|
{
|
|
return atomic_add_return(delta, (atomic_t *)(&sem->count));
|
|
}
|
|
|
|
#endif /* __KERNEL__ */
|
|
#endif /* _PPC_RWSEM_XADD_H */
|