blob: de84f8534bacd24d310a635bc1769ed3c6fd06d1 [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * atomic32.c: 32-bit atomic_t implementation
3 *
4 * Copyright (C) 2004 Keith M Wesolowski
5 *
6 * Based on asm-parisc/atomic.h Copyright (C) 2000 Philipp Rumpf
7 */
8
9#include <asm/atomic.h>
10#include <linux/spinlock.h>
11#include <linux/module.h>
12
13#ifdef CONFIG_SMP
14#define ATOMIC_HASH_SIZE 4
15#define ATOMIC_HASH(a) (&__atomic_hash[(((unsigned long)a)>>8) & (ATOMIC_HASH_SIZE-1)])
16
17spinlock_t __atomic_hash[ATOMIC_HASH_SIZE] = {
18 [0 ... (ATOMIC_HASH_SIZE-1)] = SPIN_LOCK_UNLOCKED
19};
20
21#else /* SMP */
22
Ingo Molnara9f6a0d2005-09-09 13:10:41 -070023static DEFINE_SPINLOCK(dummy);
Linus Torvalds1da177e2005-04-16 15:20:36 -070024#define ATOMIC_HASH_SIZE 1
25#define ATOMIC_HASH(a) (&dummy)
26
27#endif /* SMP */
28
29int __atomic_add_return(int i, atomic_t *v)
30{
31 int ret;
32 unsigned long flags;
33 spin_lock_irqsave(ATOMIC_HASH(v), flags);
34
35 ret = (v->counter += i);
36
37 spin_unlock_irqrestore(ATOMIC_HASH(v), flags);
38 return ret;
39}
Nick Piggin4a6dae62005-11-13 16:07:24 -080040EXPORT_SYMBOL(__atomic_add_return);
41
42int atomic_cmpxchg(atomic_t *v, int old, int new)
43{
44 int ret;
45 unsigned long flags;
46
47 spin_lock_irqsave(ATOMIC_HASH(v), flags);
48 ret = v->counter;
49 if (likely(ret == old))
50 v->counter = new;
51
52 spin_unlock_irqrestore(ATOMIC_HASH(v), flags);
53 return ret;
54}
Linus Torvalds1da177e2005-04-16 15:20:36 -070055
Nick Piggin8426e1f2005-11-13 16:07:25 -080056int atomic_add_unless(atomic_t *v, int a, int u)
57{
58 int ret;
59 unsigned long flags;
60
61 spin_lock_irqsave(ATOMIC_HASH(v), flags);
62 ret = v->counter;
63 if (ret != u)
64 v->counter += a;
65 spin_unlock_irqrestore(ATOMIC_HASH(v), flags);
66 return ret != u;
67}
68
Nick Piggin8426e1f2005-11-13 16:07:25 -080069/* Atomic operations are already serializing */
Linus Torvalds1da177e2005-04-16 15:20:36 -070070void atomic_set(atomic_t *v, int i)
71{
72 unsigned long flags;
Nick Piggin4a6dae62005-11-13 16:07:24 -080073
Linus Torvalds1da177e2005-04-16 15:20:36 -070074 spin_lock_irqsave(ATOMIC_HASH(v), flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -070075 v->counter = i;
Linus Torvalds1da177e2005-04-16 15:20:36 -070076 spin_unlock_irqrestore(ATOMIC_HASH(v), flags);
77}
Linus Torvalds1da177e2005-04-16 15:20:36 -070078EXPORT_SYMBOL(atomic_set);