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/*
* linux/include/asm-arm/semaphore.h
*/
#ifndef __ASM_ARM_SEMAPHORE_H
#define __ASM_ARM_SEMAPHORE_H
#include <linux/linkage.h>
#include <linux/spinlock.h>
#include <linux/wait.h>
#include <asm/atomic.h>
#include <asm/proc/locks.h>
struct semaphore {
atomic_t count;
int sleepers;
wait_queue_head_t wait;
#if WAITQUEUE_DEBUG
long __magic;
#endif
};
#if WAITQUEUE_DEBUG
# define __SEM_DEBUG_INIT(name) \
, (long)&(name).__magic
#else
# define __SEM_DEBUG_INIT(name)
#endif
#define __SEMAPHORE_INIT(name,count) \
{ ATOMIC_INIT(count), 0, \
__WAIT_QUEUE_HEAD_INITIALIZER((name).wait) \
__SEM_DEBUG_INIT(name) }
#define __MUTEX_INITIALIZER(name) \
__SEMAPHORE_INIT(name,1)
#define __DECLARE_SEMAPHORE_GENERIC(name,count) \
struct semaphore name = __SEMAPHORE_INIT(name,count)
#define DECLARE_MUTEX(name) __DECLARE_SEMAPHORE_GENERIC(name,1)
#define DECLARE_MUTEX_LOCKED(name) __DECLARE_SEMAPHORE_GENERIC(name,0)
extern inline void sema_init(struct semaphore *sem, int val)
{
atomic_set(&sem->count, val);
sem->sleepers = 0;
init_waitqueue_head(&sem->wait);
#if WAITQUEUE_DEBUG
sem->__magic = (long)&sem->__magic;
#endif
}
static inline void init_MUTEX(struct semaphore *sem)
{
sema_init(sem, 1);
}
static inline void init_MUTEX_LOCKED(struct semaphore *sem)
{
sema_init(sem, 0);
}
/*
* special register calling convention
*/
asmlinkage void __down_failed(void);
asmlinkage int __down_interruptible_failed(void);
asmlinkage int __down_trylock_failed(void);
asmlinkage void __up_wakeup(void);
extern void __down(struct semaphore * sem);
extern int __down_interruptible(struct semaphore * sem);
extern int __down_trylock(struct semaphore * sem);
extern void __up(struct semaphore * sem);
/*
* This is ugly, but we want the default case to fall through.
* "__down" is the actual routine that waits...
*/
extern inline void down(struct semaphore * sem)
{
#if WAITQUEUE_DEBUG
CHECK_MAGIC(sem->__magic);
#endif
__down_op(sem, __down_failed);
}
/*
* This is ugly, but we want the default case to fall through.
* "__down_interruptible" is the actual routine that waits...
*/
extern inline int down_interruptible (struct semaphore * sem)
{
#if WAITQUEUE_DEBUG
CHECK_MAGIC(sem->__magic);
#endif
return __down_op_ret(sem, __down_interruptible_failed);
}
extern inline int down_trylock(struct semaphore *sem)
{
#if WAITQUEUE_DEBUG
CHECK_MAGIC(sem->__magic);
#endif
return __down_op_ret(sem, __down_trylock_failed);
}
/*
* Note! This is subtle. We jump to wake people up only if
* the semaphore was negative (== somebody was waiting on it).
* The default case (no contention) will result in NO
* jumps for both down() and up().
*/
extern inline void up(struct semaphore * sem)
{
#if WAITQUEUE_DEBUG
CHECK_MAGIC(sem->__magic);
#endif
__up_op(sem, __up_wakeup);
}
/* rw mutexes (should that be mutices? =) -- throw rw
* spinlocks and semaphores together, and this is what we
* end up with...
*
* The lock is initialized to BIAS. This way, a writer
* subtracts BIAS ands gets 0 for the case of an uncontended
* lock. Readers decrement by 1 and see a positive value
* when uncontended, negative if there are writers waiting
* (in which case it goes to sleep).
*
* In terms of fairness, this should result in the lock
* flopping back and forth between readers and writers
* under heavy use.
*
* -ben
*/
struct rw_semaphore {
atomic_t count;
volatile unsigned char write_bias_granted;
volatile unsigned char read_bias_granted;
volatile unsigned char pad1;
volatile unsigned char pad2;
wait_queue_head_t wait;
wait_queue_head_t write_bias_wait;
#if WAITQUEUE_DEBUG
long __magic;
atomic_t readers;
atomic_t writers;
#endif
};
#if WAITQUEUE_DEBUG
#define __RWSEM_DEBUG_INIT , ATOMIC_INIT(0), ATOMIC_INIT(0)
#else
#define __RWSEM_DEBUG_INIT /* */
#endif
#define __RWSEM_INITIALIZER(name,count) \
{ ATOMIC_INIT(count), 0, 0, 0, 0, __WAIT_QUEUE_HEAD_INITIALIZER((name).wait), \
__WAIT_QUEUE_HEAD_INITIALIZER((name).write_bias_wait) \
__SEM_DEBUG_INIT(name) __RWSEM_DEBUG_INIT }
#define __DECLARE_RWSEM_GENERIC(name,count) \
struct rw_semaphore name = __RWSEM_INITIALIZER(name,count)
#define DECLARE_RWSEM(name) __DECLARE_RWSEM_GENERIC(name,RW_LOCK_BIAS)
#define DECLARE_RWSEM_READ_LOCKED(name) __DECLARE_RWSEM_GENERIC(name,RW_LOCK_BIAS-1)
#define DECLARE_RWSEM_WRITE_LOCKED(name) __DECLARE_RWSEM_GENERIC(name,0)
extern inline void init_rwsem(struct rw_semaphore *sem)
{
atomic_set(&sem->count, RW_LOCK_BIAS);
sem->read_bias_granted = 0;
sem->write_bias_granted = 0;
init_waitqueue_head(&sem->wait);
init_waitqueue_head(&sem->write_bias_wait);
#if WAITQUEUE_DEBUG
sem->__magic = (long)&sem->__magic;
atomic_set(&sem->readers, 0);
atomic_set(&sem->writers, 0);
#endif
}
extern struct rw_semaphore *__down_read_failed(struct rw_semaphore *sem);
extern struct rw_semaphore *__down_write_failed(struct rw_semaphore *sem);
extern struct rw_semaphore *__rwsem_wake(struct rw_semaphore *sem);
extern inline void down_read(struct rw_semaphore *sem)
{
#if WAITQUEUE_DEBUG
CHECK_MAGIC(sem->__magic);
#endif
__down_op_read(sem, __down_read_failed);
#if WAITQUEUE_DEBUG
if (sem->write_bias_granted)
BUG();
if (atomic_read(&sem->writers))
BUG();
atomic_inc(&sem->readers);
#endif
}
extern inline void down_write(struct rw_semaphore *sem)
{
#if WAITQUEUE_DEBUG
CHECK_MAGIC(sem->__magic);
#endif
__down_op_write(sem, __down_write_failed);
#if WAITQUEUE_DEBUG
if (atomic_read(&sem->writers))
BUG();
if (atomic_read(&sem->readers))
BUG();
if (sem->read_bias_granted)
BUG();
if (sem->write_bias_granted)
BUG();
atomic_inc(&sem->writers);
#endif
}
extern inline void up_read(struct rw_semaphore *sem)
{
#if WAITQUEUE_DEBUG
if (sem->write_bias_granted)
BUG();
if (atomic_read(&sem->writers))
BUG();
atomic_dec(&sem->readers);
#endif
__up_op_read(sem, __rwsem_wake);
}
extern inline void up_write(struct rw_semaphore *sem)
{
#if WAITQUEUE_DEBUG
if (sem->read_bias_granted)
BUG();
if (sem->write_bias_granted)
BUG();
if (atomic_read(&sem->readers))
BUG();
if (atomic_read(&sem->writers) != 1)
BUG();
atomic_dec(&sem->writers);
#endif
__up_op_write(sem, __rwsem_wake);
}
#endif
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