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