109 строки
2.5 KiB
C
109 строки
2.5 KiB
C
/*
|
|
* include/asm-s390/semaphore.h
|
|
*
|
|
* S390 version
|
|
* Copyright (C) 1999 IBM Deutschland Entwicklung GmbH, IBM Corporation
|
|
*
|
|
* Derived from "include/asm-i386/semaphore.h"
|
|
* (C) Copyright 1996 Linus Torvalds
|
|
*/
|
|
|
|
#ifndef _S390_SEMAPHORE_H
|
|
#define _S390_SEMAPHORE_H
|
|
|
|
#include <asm/system.h>
|
|
#include <asm/atomic.h>
|
|
#include <linux/wait.h>
|
|
#include <linux/rwsem.h>
|
|
|
|
struct semaphore {
|
|
/*
|
|
* Note that any negative value of count is equivalent to 0,
|
|
* but additionally indicates that some process(es) might be
|
|
* sleeping on `wait'.
|
|
*/
|
|
atomic_t count;
|
|
wait_queue_head_t wait;
|
|
};
|
|
|
|
#define __SEMAPHORE_INITIALIZER(name,count) \
|
|
{ ATOMIC_INIT(count), __WAIT_QUEUE_HEAD_INITIALIZER((name).wait) }
|
|
|
|
#define __DECLARE_SEMAPHORE_GENERIC(name,count) \
|
|
struct semaphore name = __SEMAPHORE_INITIALIZER(name,count)
|
|
|
|
#define DECLARE_MUTEX(name) __DECLARE_SEMAPHORE_GENERIC(name,1)
|
|
#define DECLARE_MUTEX_LOCKED(name) __DECLARE_SEMAPHORE_GENERIC(name,0)
|
|
|
|
static inline void sema_init (struct semaphore *sem, int val)
|
|
{
|
|
atomic_set(&sem->count, val);
|
|
init_waitqueue_head(&sem->wait);
|
|
}
|
|
|
|
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);
|
|
}
|
|
|
|
asmlinkage void __down(struct semaphore * sem);
|
|
asmlinkage int __down_interruptible(struct semaphore * sem);
|
|
asmlinkage int __down_trylock(struct semaphore * sem);
|
|
asmlinkage void __up(struct semaphore * sem);
|
|
|
|
static inline void down(struct semaphore * sem)
|
|
{
|
|
might_sleep();
|
|
if (atomic_dec_return(&sem->count) < 0)
|
|
__down(sem);
|
|
}
|
|
|
|
static inline int down_interruptible(struct semaphore * sem)
|
|
{
|
|
int ret = 0;
|
|
|
|
might_sleep();
|
|
if (atomic_dec_return(&sem->count) < 0)
|
|
ret = __down_interruptible(sem);
|
|
return ret;
|
|
}
|
|
|
|
static inline int down_trylock(struct semaphore * sem)
|
|
{
|
|
int old_val, new_val;
|
|
|
|
/*
|
|
* This inline assembly atomically implements the equivalent
|
|
* to the following C code:
|
|
* old_val = sem->count.counter;
|
|
* if ((new_val = old_val) > 0)
|
|
* sem->count.counter = --new_val;
|
|
* In the ppc code this is called atomic_dec_if_positive.
|
|
*/
|
|
asm volatile(
|
|
" l %0,0(%3)\n"
|
|
"0: ltr %1,%0\n"
|
|
" jle 1f\n"
|
|
" ahi %1,-1\n"
|
|
" cs %0,%1,0(%3)\n"
|
|
" jl 0b\n"
|
|
"1:"
|
|
: "=&d" (old_val), "=&d" (new_val), "=m" (sem->count.counter)
|
|
: "a" (&sem->count.counter), "m" (sem->count.counter)
|
|
: "cc", "memory");
|
|
return old_val <= 0;
|
|
}
|
|
|
|
static inline void up(struct semaphore * sem)
|
|
{
|
|
if (atomic_inc_return(&sem->count) <= 0)
|
|
__up(sem);
|
|
}
|
|
|
|
#endif
|