43 lines
1.1 KiB
C
43 lines
1.1 KiB
C
/*
|
|
* 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);
|