semaphore-helper.h
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/* $Id: semaphore-helper.h,v 1.3 2001/03/26 15:00:33 orjanf Exp $
*
* SMP- and interrupt-safe semaphores helper functions. Generic versions, no
* optimizations whatsoever...
*
*/
#ifndef _ASM_SEMAPHORE_HELPER_H
#define _ASM_SEMAPHORE_HELPER_H
#include <asm/atomic.h>
#include <linux/errno.h>
#define read(a) ((a)->counter)
#define inc(a) (((a)->counter)++)
#define dec(a) (((a)->counter)--)
#define count_inc(a) ((*(a))++)
/*
* These two _must_ execute atomically wrt each other.
*/
extern inline void wake_one_more(struct semaphore * sem)
{
atomic_inc(&sem->waking);
}
extern inline int waking_non_zero(struct semaphore *sem)
{
unsigned long flags;
int ret = 0;
local_save_flags(flags);
local_irq_disable();
if (read(&sem->waking) > 0) {
dec(&sem->waking);
ret = 1;
}
local_irq_restore(flags);
return ret;
}
extern inline int waking_non_zero_interruptible(struct semaphore *sem,
struct task_struct *tsk)
{
int ret = 0;
unsigned long flags;
local_save_flags(flags);
local_irq_disable();
if (read(&sem->waking) > 0) {
dec(&sem->waking);
ret = 1;
} else if (signal_pending(tsk)) {
inc(&sem->count);
ret = -EINTR;
}
local_irq_restore(flags);
return ret;
}
extern inline int waking_non_zero_trylock(struct semaphore *sem)
{
int ret = 1;
unsigned long flags;
local_save_flags(flags);
local_irq_disable();
if (read(&sem->waking) <= 0)
inc(&sem->count);
else {
dec(&sem->waking);
ret = 0;
}
local_irq_restore(flags);
return ret;
}
#endif /* _ASM_SEMAPHORE_HELPER_H */