atomic32.c
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/*
* atomic32.c: 32-bit atomic_t implementation
*
* Copyright (C) 2004 Keith M Wesolowski
* Copyright (C) 2007 Kyle McMartin
*
* Based on asm-parisc/atomic.h Copyright (C) 2000 Philipp Rumpf
*/
#include <linux/atomic.h>
#include <linux/spinlock.h>
#include <linux/module.h>
#ifdef CONFIG_SMP
#define ATOMIC_HASH_SIZE 4
#define ATOMIC_HASH(a) (&__atomic_hash[(((unsigned long)a)>>8) & (ATOMIC_HASH_SIZE-1)])
spinlock_t __atomic_hash[ATOMIC_HASH_SIZE] = {
[0 ... (ATOMIC_HASH_SIZE-1)] = __SPIN_LOCK_UNLOCKED(__atomic_hash)
};
#else /* SMP */
static DEFINE_SPINLOCK(dummy);
#define ATOMIC_HASH_SIZE 1
#define ATOMIC_HASH(a) (&dummy)
#endif /* SMP */
int __atomic_add_return(int i, atomic_t *v)
{
int ret;
unsigned long flags;
spin_lock_irqsave(ATOMIC_HASH(v), flags);
ret = (v->counter += i);
spin_unlock_irqrestore(ATOMIC_HASH(v), flags);
return ret;
}
EXPORT_SYMBOL(__atomic_add_return);
int atomic_xchg(atomic_t *v, int new)
{
int ret;
unsigned long flags;
spin_lock_irqsave(ATOMIC_HASH(v), flags);
ret = v->counter;
v->counter = new;
spin_unlock_irqrestore(ATOMIC_HASH(v), flags);
return ret;
}
EXPORT_SYMBOL(atomic_xchg);
int atomic_cmpxchg(atomic_t *v, int old, int new)
{
int ret;
unsigned long flags;
spin_lock_irqsave(ATOMIC_HASH(v), flags);
ret = v->counter;
if (likely(ret == old))
v->counter = new;
spin_unlock_irqrestore(ATOMIC_HASH(v), flags);
return ret;
}
EXPORT_SYMBOL(atomic_cmpxchg);
int __atomic_add_unless(atomic_t *v, int a, int u)
{
int ret;
unsigned long flags;
spin_lock_irqsave(ATOMIC_HASH(v), flags);
ret = v->counter;
if (ret != u)
v->counter += a;
spin_unlock_irqrestore(ATOMIC_HASH(v), flags);
return ret;
}
EXPORT_SYMBOL(__atomic_add_unless);
/* Atomic operations are already serializing */
void atomic_set(atomic_t *v, int i)
{
unsigned long flags;
spin_lock_irqsave(ATOMIC_HASH(v), flags);
v->counter = i;
spin_unlock_irqrestore(ATOMIC_HASH(v), flags);
}
EXPORT_SYMBOL(atomic_set);
unsigned long ___set_bit(unsigned long *addr, unsigned long mask)
{
unsigned long old, flags;
spin_lock_irqsave(ATOMIC_HASH(addr), flags);
old = *addr;
*addr = old | mask;
spin_unlock_irqrestore(ATOMIC_HASH(addr), flags);
return old & mask;
}
EXPORT_SYMBOL(___set_bit);
unsigned long ___clear_bit(unsigned long *addr, unsigned long mask)
{
unsigned long old, flags;
spin_lock_irqsave(ATOMIC_HASH(addr), flags);
old = *addr;
*addr = old & ~mask;
spin_unlock_irqrestore(ATOMIC_HASH(addr), flags);
return old & mask;
}
EXPORT_SYMBOL(___clear_bit);
unsigned long ___change_bit(unsigned long *addr, unsigned long mask)
{
unsigned long old, flags;
spin_lock_irqsave(ATOMIC_HASH(addr), flags);
old = *addr;
*addr = old ^ mask;
spin_unlock_irqrestore(ATOMIC_HASH(addr), flags);
return old & mask;
}
EXPORT_SYMBOL(___change_bit);
unsigned long __cmpxchg_u32(volatile u32 *ptr, u32 old, u32 new)
{
unsigned long flags;
u32 prev;
spin_lock_irqsave(ATOMIC_HASH(ptr), flags);
if ((prev = *ptr) == old)
*ptr = new;
spin_unlock_irqrestore(ATOMIC_HASH(ptr), flags);
return (unsigned long)prev;
}
EXPORT_SYMBOL(__cmpxchg_u32);
unsigned long __xchg_u32(volatile u32 *ptr, u32 new)
{
unsigned long flags;
u32 prev;
spin_lock_irqsave(ATOMIC_HASH(ptr), flags);
prev = *ptr;
*ptr = new;
spin_unlock_irqrestore(ATOMIC_HASH(ptr), flags);
return (unsigned long)prev;
}
EXPORT_SYMBOL(__xchg_u32);