79 lines
1.6 KiB
C
79 lines
1.6 KiB
C
/*
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* atomic32.c: 32-bit atomic_t implementation
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*
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* Copyright (C) 2004 Keith M Wesolowski
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*
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* Based on asm-parisc/atomic.h Copyright (C) 2000 Philipp Rumpf
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*/
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#include <asm/atomic.h>
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#include <linux/spinlock.h>
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#include <linux/module.h>
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#ifdef CONFIG_SMP
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#define ATOMIC_HASH_SIZE 4
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#define ATOMIC_HASH(a) (&__atomic_hash[(((unsigned long)a)>>8) & (ATOMIC_HASH_SIZE-1)])
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spinlock_t __atomic_hash[ATOMIC_HASH_SIZE] = {
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[0 ... (ATOMIC_HASH_SIZE-1)] = SPIN_LOCK_UNLOCKED
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};
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#else /* SMP */
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static DEFINE_SPINLOCK(dummy);
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#define ATOMIC_HASH_SIZE 1
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#define ATOMIC_HASH(a) (&dummy)
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#endif /* SMP */
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int __atomic_add_return(int i, atomic_t *v)
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{
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int ret;
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unsigned long flags;
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spin_lock_irqsave(ATOMIC_HASH(v), flags);
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ret = (v->counter += i);
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spin_unlock_irqrestore(ATOMIC_HASH(v), flags);
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return ret;
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}
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EXPORT_SYMBOL(__atomic_add_return);
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int atomic_cmpxchg(atomic_t *v, int old, int new)
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{
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int ret;
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unsigned long flags;
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spin_lock_irqsave(ATOMIC_HASH(v), flags);
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ret = v->counter;
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if (likely(ret == old))
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v->counter = new;
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spin_unlock_irqrestore(ATOMIC_HASH(v), flags);
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return ret;
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}
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int atomic_add_unless(atomic_t *v, int a, int u)
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{
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int ret;
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unsigned long flags;
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spin_lock_irqsave(ATOMIC_HASH(v), flags);
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ret = v->counter;
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if (ret != u)
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v->counter += a;
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spin_unlock_irqrestore(ATOMIC_HASH(v), flags);
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return ret != u;
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}
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/* Atomic operations are already serializing */
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void atomic_set(atomic_t *v, int i)
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{
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unsigned long flags;
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spin_lock_irqsave(ATOMIC_HASH(v), flags);
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v->counter = i;
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spin_unlock_irqrestore(ATOMIC_HASH(v), flags);
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}
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EXPORT_SYMBOL(atomic_set);
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