Blame view
lib/atomic64.c
4.25 KB
09d4e0edd
|
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 |
/* * Generic implementation of 64-bit atomics using spinlocks, * useful on processors that don't have 64-bit atomic instructions. * * Copyright © 2009 Paul Mackerras, IBM Corp. <paulus@au1.ibm.com> * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License * as published by the Free Software Foundation; either version * 2 of the License, or (at your option) any later version. */ #include <linux/types.h> #include <linux/cache.h> #include <linux/spinlock.h> #include <linux/init.h> |
3fc7b4b22
|
16 |
#include <linux/module.h> |
60063497a
|
17 |
#include <linux/atomic.h> |
09d4e0edd
|
18 19 20 21 22 23 24 25 26 27 28 29 30 31 |
/* * We use a hashed array of spinlocks to provide exclusive access * to each atomic64_t variable. Since this is expected to used on * systems with small numbers of CPUs (<= 4 or so), we use a * relatively small array of 16 spinlocks to avoid wasting too much * memory on the spinlock array. */ #define NR_LOCKS 16 /* * Ensure each lock is in a separate cacheline. */ static union { |
f59ca0587
|
32 |
raw_spinlock_t lock; |
09d4e0edd
|
33 34 |
char pad[L1_CACHE_BYTES]; } atomic64_lock[NR_LOCKS] __cacheline_aligned_in_smp; |
cb475de3d
|
35 |
static inline raw_spinlock_t *lock_addr(const atomic64_t *v) |
09d4e0edd
|
36 37 38 39 40 41 42 43 44 45 46 |
{ unsigned long addr = (unsigned long) v; addr >>= L1_CACHE_SHIFT; addr ^= (addr >> 8) ^ (addr >> 16); return &atomic64_lock[addr & (NR_LOCKS - 1)].lock; } long long atomic64_read(const atomic64_t *v) { unsigned long flags; |
cb475de3d
|
47 |
raw_spinlock_t *lock = lock_addr(v); |
09d4e0edd
|
48 |
long long val; |
f59ca0587
|
49 |
raw_spin_lock_irqsave(lock, flags); |
09d4e0edd
|
50 |
val = v->counter; |
f59ca0587
|
51 |
raw_spin_unlock_irqrestore(lock, flags); |
09d4e0edd
|
52 53 |
return val; } |
3fc7b4b22
|
54 |
EXPORT_SYMBOL(atomic64_read); |
09d4e0edd
|
55 56 57 58 |
void atomic64_set(atomic64_t *v, long long i) { unsigned long flags; |
cb475de3d
|
59 |
raw_spinlock_t *lock = lock_addr(v); |
09d4e0edd
|
60 |
|
f59ca0587
|
61 |
raw_spin_lock_irqsave(lock, flags); |
09d4e0edd
|
62 |
v->counter = i; |
f59ca0587
|
63 |
raw_spin_unlock_irqrestore(lock, flags); |
09d4e0edd
|
64 |
} |
3fc7b4b22
|
65 |
EXPORT_SYMBOL(atomic64_set); |
09d4e0edd
|
66 67 68 69 |
void atomic64_add(long long a, atomic64_t *v) { unsigned long flags; |
cb475de3d
|
70 |
raw_spinlock_t *lock = lock_addr(v); |
09d4e0edd
|
71 |
|
f59ca0587
|
72 |
raw_spin_lock_irqsave(lock, flags); |
09d4e0edd
|
73 |
v->counter += a; |
f59ca0587
|
74 |
raw_spin_unlock_irqrestore(lock, flags); |
09d4e0edd
|
75 |
} |
3fc7b4b22
|
76 |
EXPORT_SYMBOL(atomic64_add); |
09d4e0edd
|
77 78 79 80 |
long long atomic64_add_return(long long a, atomic64_t *v) { unsigned long flags; |
cb475de3d
|
81 |
raw_spinlock_t *lock = lock_addr(v); |
09d4e0edd
|
82 |
long long val; |
f59ca0587
|
83 |
raw_spin_lock_irqsave(lock, flags); |
09d4e0edd
|
84 |
val = v->counter += a; |
f59ca0587
|
85 |
raw_spin_unlock_irqrestore(lock, flags); |
09d4e0edd
|
86 87 |
return val; } |
3fc7b4b22
|
88 |
EXPORT_SYMBOL(atomic64_add_return); |
09d4e0edd
|
89 90 91 92 |
void atomic64_sub(long long a, atomic64_t *v) { unsigned long flags; |
cb475de3d
|
93 |
raw_spinlock_t *lock = lock_addr(v); |
09d4e0edd
|
94 |
|
f59ca0587
|
95 |
raw_spin_lock_irqsave(lock, flags); |
09d4e0edd
|
96 |
v->counter -= a; |
f59ca0587
|
97 |
raw_spin_unlock_irqrestore(lock, flags); |
09d4e0edd
|
98 |
} |
3fc7b4b22
|
99 |
EXPORT_SYMBOL(atomic64_sub); |
09d4e0edd
|
100 101 102 103 |
long long atomic64_sub_return(long long a, atomic64_t *v) { unsigned long flags; |
cb475de3d
|
104 |
raw_spinlock_t *lock = lock_addr(v); |
09d4e0edd
|
105 |
long long val; |
f59ca0587
|
106 |
raw_spin_lock_irqsave(lock, flags); |
09d4e0edd
|
107 |
val = v->counter -= a; |
f59ca0587
|
108 |
raw_spin_unlock_irqrestore(lock, flags); |
09d4e0edd
|
109 110 |
return val; } |
3fc7b4b22
|
111 |
EXPORT_SYMBOL(atomic64_sub_return); |
09d4e0edd
|
112 113 114 115 |
long long atomic64_dec_if_positive(atomic64_t *v) { unsigned long flags; |
cb475de3d
|
116 |
raw_spinlock_t *lock = lock_addr(v); |
09d4e0edd
|
117 |
long long val; |
f59ca0587
|
118 |
raw_spin_lock_irqsave(lock, flags); |
09d4e0edd
|
119 120 121 |
val = v->counter - 1; if (val >= 0) v->counter = val; |
f59ca0587
|
122 |
raw_spin_unlock_irqrestore(lock, flags); |
09d4e0edd
|
123 124 |
return val; } |
3fc7b4b22
|
125 |
EXPORT_SYMBOL(atomic64_dec_if_positive); |
09d4e0edd
|
126 127 128 129 |
long long atomic64_cmpxchg(atomic64_t *v, long long o, long long n) { unsigned long flags; |
cb475de3d
|
130 |
raw_spinlock_t *lock = lock_addr(v); |
09d4e0edd
|
131 |
long long val; |
f59ca0587
|
132 |
raw_spin_lock_irqsave(lock, flags); |
09d4e0edd
|
133 134 135 |
val = v->counter; if (val == o) v->counter = n; |
f59ca0587
|
136 |
raw_spin_unlock_irqrestore(lock, flags); |
09d4e0edd
|
137 138 |
return val; } |
3fc7b4b22
|
139 |
EXPORT_SYMBOL(atomic64_cmpxchg); |
09d4e0edd
|
140 141 142 143 |
long long atomic64_xchg(atomic64_t *v, long long new) { unsigned long flags; |
cb475de3d
|
144 |
raw_spinlock_t *lock = lock_addr(v); |
09d4e0edd
|
145 |
long long val; |
f59ca0587
|
146 |
raw_spin_lock_irqsave(lock, flags); |
09d4e0edd
|
147 148 |
val = v->counter; v->counter = new; |
f59ca0587
|
149 |
raw_spin_unlock_irqrestore(lock, flags); |
09d4e0edd
|
150 151 |
return val; } |
3fc7b4b22
|
152 |
EXPORT_SYMBOL(atomic64_xchg); |
09d4e0edd
|
153 154 155 156 |
int atomic64_add_unless(atomic64_t *v, long long a, long long u) { unsigned long flags; |
cb475de3d
|
157 |
raw_spinlock_t *lock = lock_addr(v); |
97577896f
|
158 |
int ret = 0; |
09d4e0edd
|
159 |
|
f59ca0587
|
160 |
raw_spin_lock_irqsave(lock, flags); |
09d4e0edd
|
161 162 |
if (v->counter != u) { v->counter += a; |
97577896f
|
163 |
ret = 1; |
09d4e0edd
|
164 |
} |
f59ca0587
|
165 |
raw_spin_unlock_irqrestore(lock, flags); |
09d4e0edd
|
166 167 |
return ret; } |
3fc7b4b22
|
168 |
EXPORT_SYMBOL(atomic64_add_unless); |
09d4e0edd
|
169 170 171 172 173 174 |
static int init_atomic64_lock(void) { int i; for (i = 0; i < NR_LOCKS; ++i) |
f59ca0587
|
175 |
raw_spin_lock_init(&atomic64_lock[i].lock); |
09d4e0edd
|
176 177 178 179 |
return 0; } pure_initcall(init_atomic64_lock); |