90 lines
2.1 KiB
C
90 lines
2.1 KiB
C
|
#ifndef __ASM_SH_SEMAPHORE_HELPER_H
|
||
|
|
#define __ASM_SH_SEMAPHORE_HELPER_H
|
||
|
|
|
||
|
|
/*
|
||
|
|
* SMP- and interrupt-safe semaphores helper functions.
|
||
|
|
*
|
||
|
|
* (C) Copyright 1996 Linus Torvalds
|
||
|
|
* (C) Copyright 1999 Andrea Arcangeli
|
||
|
|
*/
|
||
|
|
|
||
|
|
/*
|
||
|
|
* These two _must_ execute atomically wrt each other.
|
||
|
|
*
|
||
|
|
* This is trivially done with load_locked/store_cond,
|
||
|
|
* which we have. Let the rest of the losers suck eggs.
|
||
|
|
*/
|
||
|
|
static __inline__ void wake_one_more(struct semaphore * sem)
|
||
|
|
{
|
||
|
|
atomic_inc((atomic_t *)&sem->sleepers);
|
||
|
|
}
|
||
|
|
|
||
|
|
static __inline__ int waking_non_zero(struct semaphore *sem)
|
||
|
|
{
|
||
|
|
unsigned long flags;
|
||
|
|
int ret = 0;
|
||
|
|
|
||
|
|
spin_lock_irqsave(&semaphore_wake_lock, flags);
|
||
|
|
if (sem->sleepers > 0) {
|
||
|
|
sem->sleepers--;
|
||
|
|
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
|
||
|
|
*
|
||
|
|
* We must undo the sem->count down_interruptible() increment while we are
|
||
|
|
* protected by the spinlock in order to make atomic this atomic_inc() with the
|
||
|
|
* atomic_read() in wake_one_more(), otherwise we can race. -arca
|
||
|
|
*/
|
||
|
|
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->sleepers > 0) {
|
||
|
|
sem->sleepers--;
|
||
|
|
ret = 1;
|
||
|
|
} else if (signal_pending(tsk)) {
|
||
|
|
atomic_inc(&sem->count);
|
||
|
|
ret = -EINTR;
|
||
|
|
}
|
||
|
|
spin_unlock_irqrestore(&semaphore_wake_lock, flags);
|
||
|
|
return ret;
|
||
|
|
}
|
||
|
|
|
||
|
|
/*
|
||
|
|
* waking_non_zero_trylock:
|
||
|
|
* 1 failed to lock
|
||
|
|
* 0 got the lock
|
||
|
|
*
|
||
|
|
* We must undo the sem->count down_trylock() increment while we are
|
||
|
|
* protected by the spinlock in order to make atomic this atomic_inc() with the
|
||
|
|
* atomic_read() in wake_one_more(), otherwise we can race. -arca
|
||
|
|
*/
|
||
|
|
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->sleepers <= 0)
|
||
|
|
atomic_inc(&sem->count);
|
||
|
|
else {
|
||
|
|
sem->sleepers--;
|
||
|
|
ret = 0;
|
||
|
|
}
|
||
|
|
spin_unlock_irqrestore(&semaphore_wake_lock, flags);
|
||
|
|
return ret;
|
||
|
|
}
|
||
|
|
|
||
|
|
#endif /* __ASM_SH_SEMAPHORE_HELPER_H */
|