8426e1f6af
Introduce an atomic_inc_not_zero operation. Make this a special case of atomic_add_unless because lockless pagecache actually wants atomic_inc_not_negativeone due to its offset refcount. Signed-off-by: Nick Piggin <npiggin@suse.de> Cc: "Paul E. McKenney" <paulmck@us.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
80 lines
1.6 KiB
C
80 lines
1.6 KiB
C
/*
|
|
* atomic32.c: 32-bit atomic_t implementation
|
|
*
|
|
* Copyright (C) 2004 Keith M Wesolowski
|
|
*
|
|
* Based on asm-parisc/atomic.h Copyright (C) 2000 Philipp Rumpf
|
|
*/
|
|
|
|
#include <asm/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
|
|
};
|
|
|
|
#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_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;
|
|
}
|
|
|
|
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 != u;
|
|
}
|
|
|
|
static inline void atomic_clear_mask(unsigned long mask, unsigned long *addr)
|
|
/* 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);
|