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/*
* include/asm-s390/semaphore-helper.h
*
* S390 version
* Copyright (C) 1999 IBM Deutschland Entwicklung GmbH, IBM Corporation
*
* Derived from "include/asm-i386/semaphore-helper.h"
* (C) Copyright 1996 Linus Torvalds
* (C) Copyright 1999 Andrea Arcangeli
*/
#ifndef _S390_SEMAPHORE_HELPER_H
#define _S390_SEMAPHORE_HELPER_H
/*
* These two _must_ execute atomically wrt each other.
*
* This is trivially done with load_locked/store_cond,
* but on the x86 we need an external synchronizer.
*/
static inline void wake_one_more(struct semaphore * sem)
{
unsigned long flags;
spin_lock_irqsave(&semaphore_wake_lock, flags);
sem->waking++;
spin_unlock_irqrestore(&semaphore_wake_lock, flags);
}
static inline int waking_non_zero(struct semaphore *sem)
{
unsigned long flags;
int ret = 0;
spin_lock_irqsave(&semaphore_wake_lock, flags);
if (sem->waking > 0) {
sem->waking--;
ret = 1;
}
spin_unlock_irqrestore(&semaphore_wake_lock, flags);
return ret;
}
/*
* waking_non_zero_interruptible:
* 1 got the lock
* 0 go to sleep
* -EINTR interrupted
*
* If we give up we must undo our count-decrease we previously did in down().
* Subtle: up() can continue to happens and increase the semaphore count
* even during our critical section protected by the spinlock. So
* we must remeber to undo the sem->waking that will be run from
* wake_one_more() some time soon, if the semaphore count become > 0.
*/
static inline int waking_non_zero_interruptible(struct semaphore *sem,
struct task_struct *tsk)
{
unsigned long flags;
int ret = 0;
spin_lock_irqsave(&semaphore_wake_lock, flags);
if (sem->waking > 0) {
sem->waking--;
ret = 1;
} else if (signal_pending(tsk)) {
if (atomic_inc_and_test_greater_zero(&sem->count))
sem->waking--;
ret = -EINTR;
}
spin_unlock_irqrestore(&semaphore_wake_lock, flags);
return ret;
}
/*
* waking_non_zero_trylock:
* 1 failed to lock
* 0 got the lock
*
* Implementation details are the same of the interruptible case.
*/
static inline int waking_non_zero_trylock(struct semaphore *sem)
{
unsigned long flags;
int ret = 1;
spin_lock_irqsave(&semaphore_wake_lock, flags);
if (sem->waking <= 0)
{
if (atomic_inc_and_test_greater_zero(&sem->count))
sem->waking--;
} else {
sem->waking--;
ret = 0;
}
spin_unlock_irqrestore(&semaphore_wake_lock, flags);
return ret;
}
#endif
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