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/*
* Copyright (C) 2003 Jerome Marchand, Bull S.A.
* Cleaned up by David Mosberger-Tang <davidm@hpl.hp.com>
*
* This file is released under the GPLv2, or at your option any later version.
*
* ia64 version of "atomic_dec_and_lock()" using the atomic "cmpxchg" instruction. This
* code is an adaptation of the x86 version of "atomic_dec_and_lock()".
*/
#include <linux/compiler.h>
#include <linux/module.h>
#include <linux/spinlock.h>
#include <asm/atomic.h>
/*
* Decrement REFCOUNT and if the count reaches zero, acquire the spinlock. Both of these
* operations have to be done atomically, so that the count doesn't drop to zero without
* acquiring the spinlock first.
*/
int
_atomic_dec_and_lock (atomic_t *refcount, spinlock_t *lock)
{
int old, new;
do {
old = atomic_read(refcount);
new = old - 1;
if (unlikely (old == 1)) {
/* oops, we may be decrementing to zero, do it the slow way... */
spin_lock(lock);
if (atomic_dec_and_test(refcount))
return 1;
spin_unlock(lock);
return 0;
}
} while (cmpxchg(&refcount->counter, old, new) != old);
return 0;
}
EXPORT_SYMBOL(_atomic_dec_and_lock);
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