79 lines
1.4 KiB
C
79 lines
1.4 KiB
C
/* $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.
|
|
*/
|
|
static inline void wake_one_more(struct semaphore * sem)
|
|
{
|
|
atomic_inc(&sem->waking);
|
|
}
|
|
|
|
static inline int waking_non_zero(struct semaphore *sem)
|
|
{
|
|
unsigned long flags;
|
|
int ret = 0;
|
|
|
|
local_irq_save(flags);
|
|
if (read(&sem->waking) > 0) {
|
|
dec(&sem->waking);
|
|
ret = 1;
|
|
}
|
|
local_irq_restore(flags);
|
|
return ret;
|
|
}
|
|
|
|
static inline int waking_non_zero_interruptible(struct semaphore *sem,
|
|
struct task_struct *tsk)
|
|
{
|
|
int ret = 0;
|
|
unsigned long flags;
|
|
|
|
local_irq_save(flags);
|
|
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;
|
|
}
|
|
|
|
static inline int waking_non_zero_trylock(struct semaphore *sem)
|
|
{
|
|
int ret = 1;
|
|
unsigned long flags;
|
|
|
|
local_irq_save(flags);
|
|
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 */
|
|
|
|
|