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