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atomic32.c
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1 /*
2  * atomic32.c: 32-bit atomic_t implementation
3  *
4  * Copyright (C) 2004 Keith M Wesolowski
5  * Copyright (C) 2007 Kyle McMartin
6  *
7  * Based on asm-parisc/atomic.h Copyright (C) 2000 Philipp Rumpf
8  */
9 
10 #include <linux/atomic.h>
11 #include <linux/spinlock.h>
12 #include <linux/module.h>
13 
14 #ifdef CONFIG_SMP
15 #define ATOMIC_HASH_SIZE 4
16 #define ATOMIC_HASH(a) (&__atomic_hash[(((unsigned long)a)>>8) & (ATOMIC_HASH_SIZE-1)])
17 
18 spinlock_t __atomic_hash[ATOMIC_HASH_SIZE] = {
19  [0 ... (ATOMIC_HASH_SIZE-1)] = __SPIN_LOCK_UNLOCKED(__atomic_hash)
20 };
21 
22 #else /* SMP */
23 
24 static DEFINE_SPINLOCK(dummy);
25 #define ATOMIC_HASH_SIZE 1
26 #define ATOMIC_HASH(a) (&dummy)
27 
28 #endif /* SMP */
29 
30 int __atomic_add_return(int i, atomic_t *v)
31 {
32  int ret;
33  unsigned long flags;
34  spin_lock_irqsave(ATOMIC_HASH(v), flags);
35 
36  ret = (v->counter += i);
37 
38  spin_unlock_irqrestore(ATOMIC_HASH(v), flags);
39  return ret;
40 }
41 EXPORT_SYMBOL(__atomic_add_return);
42 
43 int atomic_cmpxchg(atomic_t *v, int old, int new)
44 {
45  int ret;
46  unsigned long flags;
47 
48  spin_lock_irqsave(ATOMIC_HASH(v), flags);
49  ret = v->counter;
50  if (likely(ret == old))
51  v->counter = new;
52 
53  spin_unlock_irqrestore(ATOMIC_HASH(v), flags);
54  return ret;
55 }
56 EXPORT_SYMBOL(atomic_cmpxchg);
57 
58 int __atomic_add_unless(atomic_t *v, int a, int u)
59 {
60  int ret;
61  unsigned long flags;
62 
63  spin_lock_irqsave(ATOMIC_HASH(v), flags);
64  ret = v->counter;
65  if (ret != u)
66  v->counter += a;
67  spin_unlock_irqrestore(ATOMIC_HASH(v), flags);
68  return ret;
69 }
70 EXPORT_SYMBOL(__atomic_add_unless);
71 
72 /* Atomic operations are already serializing */
73 void atomic_set(atomic_t *v, int i)
74 {
75  unsigned long flags;
76 
77  spin_lock_irqsave(ATOMIC_HASH(v), flags);
78  v->counter = i;
79  spin_unlock_irqrestore(ATOMIC_HASH(v), flags);
80 }
81 EXPORT_SYMBOL(atomic_set);
82 
83 unsigned long ___set_bit(unsigned long *addr, unsigned long mask)
84 {
85  unsigned long old, flags;
86 
87  spin_lock_irqsave(ATOMIC_HASH(addr), flags);
88  old = *addr;
89  *addr = old | mask;
90  spin_unlock_irqrestore(ATOMIC_HASH(addr), flags);
91 
92  return old & mask;
93 }
94 EXPORT_SYMBOL(___set_bit);
95 
96 unsigned long ___clear_bit(unsigned long *addr, unsigned long mask)
97 {
98  unsigned long old, flags;
99 
100  spin_lock_irqsave(ATOMIC_HASH(addr), flags);
101  old = *addr;
102  *addr = old & ~mask;
103  spin_unlock_irqrestore(ATOMIC_HASH(addr), flags);
104 
105  return old & mask;
106 }
107 EXPORT_SYMBOL(___clear_bit);
108 
109 unsigned long ___change_bit(unsigned long *addr, unsigned long mask)
110 {
111  unsigned long old, flags;
112 
113  spin_lock_irqsave(ATOMIC_HASH(addr), flags);
114  old = *addr;
115  *addr = old ^ mask;
116  spin_unlock_irqrestore(ATOMIC_HASH(addr), flags);
117 
118  return old & mask;
119 }
120 EXPORT_SYMBOL(___change_bit);
121 
122 unsigned long __cmpxchg_u32(volatile u32 *ptr, u32 old, u32 new)
123 {
124  unsigned long flags;
125  u32 prev;
126 
127  spin_lock_irqsave(ATOMIC_HASH(ptr), flags);
128  if ((prev = *ptr) == old)
129  *ptr = new;
130  spin_unlock_irqrestore(ATOMIC_HASH(ptr), flags);
131 
132  return (unsigned long)prev;
133 }
134 EXPORT_SYMBOL(__cmpxchg_u32);
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