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| Rev | Author | Line No. | Line |
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| 422 | giacomo | 1 | #ifndef __ARCH_I386_ATOMIC__ |
| 2 | #define __ARCH_I386_ATOMIC__ |
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| 3 | |||
| 4 | #include <linux/config.h> |
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| 5 | |||
| 6 | /* |
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| 7 | * Atomic operations that C can't guarantee us. Useful for |
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| 8 | * resource counting etc.. |
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| 9 | */ |
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| 10 | |||
| 11 | #ifdef CONFIG_SMP |
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| 12 | #define LOCK "lock ; " |
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| 13 | #else |
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| 14 | #define LOCK "" |
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| 15 | #endif |
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| 16 | |||
| 17 | /* |
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| 18 | * Make sure gcc doesn't try to be clever and move things around |
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| 19 | * on us. We need to use _exactly_ the address the user gave us, |
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| 20 | * not some alias that contains the same information. |
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| 21 | */ |
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| 22 | typedef struct { volatile int counter; } atomic_t; |
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| 23 | |||
| 24 | #define ATOMIC_INIT(i) { (i) } |
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| 25 | |||
| 26 | /** |
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| 27 | * atomic_read - read atomic variable |
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| 28 | * @v: pointer of type atomic_t |
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| 29 | * |
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| 30 | * Atomically reads the value of @v. Note that the guaranteed |
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| 31 | * useful range of an atomic_t is only 24 bits. |
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| 32 | */ |
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| 33 | #define atomic_read(v) ((v)->counter) |
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| 34 | |||
| 35 | /** |
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| 36 | * atomic_set - set atomic variable |
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| 37 | * @v: pointer of type atomic_t |
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| 38 | * @i: required value |
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| 39 | * |
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| 40 | * Atomically sets the value of @v to @i. Note that the guaranteed |
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| 41 | * useful range of an atomic_t is only 24 bits. |
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| 42 | */ |
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| 43 | #define atomic_set(v,i) (((v)->counter) = (i)) |
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| 44 | |||
| 45 | /** |
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| 46 | * atomic_add - add integer to atomic variable |
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| 47 | * @i: integer value to add |
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| 48 | * @v: pointer of type atomic_t |
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| 49 | * |
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| 50 | * Atomically adds @i to @v. Note that the guaranteed useful range |
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| 51 | * of an atomic_t is only 24 bits. |
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| 52 | */ |
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| 53 | static __inline__ void atomic_add(int i, atomic_t *v) |
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| 54 | { |
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| 55 | __asm__ __volatile__( |
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| 56 | LOCK "addl %1,%0" |
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| 57 | :"=m" (v->counter) |
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| 58 | :"ir" (i), "m" (v->counter)); |
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| 59 | } |
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| 60 | |||
| 61 | /** |
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| 62 | * atomic_sub - subtract the atomic variable |
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| 63 | * @i: integer value to subtract |
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| 64 | * @v: pointer of type atomic_t |
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| 65 | * |
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| 66 | * Atomically subtracts @i from @v. Note that the guaranteed |
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| 67 | * useful range of an atomic_t is only 24 bits. |
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| 68 | */ |
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| 69 | static __inline__ void atomic_sub(int i, atomic_t *v) |
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| 70 | { |
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| 71 | __asm__ __volatile__( |
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| 72 | LOCK "subl %1,%0" |
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| 73 | :"=m" (v->counter) |
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| 74 | :"ir" (i), "m" (v->counter)); |
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| 75 | } |
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| 76 | |||
| 77 | /** |
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| 78 | * atomic_sub_and_test - subtract value from variable and test result |
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| 79 | * @i: integer value to subtract |
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| 80 | * @v: pointer of type atomic_t |
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| 81 | * |
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| 82 | * Atomically subtracts @i from @v and returns |
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| 83 | * true if the result is zero, or false for all |
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| 84 | * other cases. Note that the guaranteed |
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| 85 | * useful range of an atomic_t is only 24 bits. |
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| 86 | */ |
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| 87 | static __inline__ int atomic_sub_and_test(int i, atomic_t *v) |
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| 88 | { |
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| 89 | unsigned char c; |
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| 90 | |||
| 91 | __asm__ __volatile__( |
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| 92 | LOCK "subl %2,%0; sete %1" |
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| 93 | :"=m" (v->counter), "=qm" (c) |
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| 94 | :"ir" (i), "m" (v->counter) : "memory"); |
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| 95 | return c; |
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| 96 | } |
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| 97 | |||
| 98 | /** |
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| 99 | * atomic_inc - increment atomic variable |
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| 100 | * @v: pointer of type atomic_t |
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| 101 | * |
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| 102 | * Atomically increments @v by 1. Note that the guaranteed |
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| 103 | * useful range of an atomic_t is only 24 bits. |
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| 104 | */ |
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| 105 | static __inline__ void atomic_inc(atomic_t *v) |
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| 106 | { |
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| 107 | __asm__ __volatile__( |
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| 108 | LOCK "incl %0" |
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| 109 | :"=m" (v->counter) |
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| 110 | :"m" (v->counter)); |
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| 111 | } |
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| 112 | |||
| 113 | /** |
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| 114 | * atomic_dec - decrement atomic variable |
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| 115 | * @v: pointer of type atomic_t |
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| 116 | * |
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| 117 | * Atomically decrements @v by 1. Note that the guaranteed |
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| 118 | * useful range of an atomic_t is only 24 bits. |
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| 119 | */ |
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| 120 | static __inline__ void atomic_dec(atomic_t *v) |
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| 121 | { |
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| 122 | __asm__ __volatile__( |
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| 123 | LOCK "decl %0" |
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| 124 | :"=m" (v->counter) |
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| 125 | :"m" (v->counter)); |
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| 126 | } |
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| 127 | |||
| 128 | /** |
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| 129 | * atomic_dec_and_test - decrement and test |
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| 130 | * @v: pointer of type atomic_t |
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| 131 | * |
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| 132 | * Atomically decrements @v by 1 and |
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| 133 | * returns true if the result is 0, or false for all other |
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| 134 | * cases. Note that the guaranteed |
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| 135 | * useful range of an atomic_t is only 24 bits. |
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| 136 | */ |
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| 137 | static __inline__ int atomic_dec_and_test(atomic_t *v) |
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| 138 | { |
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| 139 | unsigned char c; |
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| 140 | |||
| 141 | __asm__ __volatile__( |
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| 142 | LOCK "decl %0; sete %1" |
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| 143 | :"=m" (v->counter), "=qm" (c) |
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| 144 | :"m" (v->counter) : "memory"); |
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| 145 | return c != 0; |
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| 146 | } |
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| 147 | |||
| 148 | /** |
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| 149 | * atomic_inc_and_test - increment and test |
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| 150 | * @v: pointer of type atomic_t |
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| 151 | * |
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| 152 | * Atomically increments @v by 1 |
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| 153 | * and returns true if the result is zero, or false for all |
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| 154 | * other cases. Note that the guaranteed |
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| 155 | * useful range of an atomic_t is only 24 bits. |
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| 156 | */ |
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| 157 | static __inline__ int atomic_inc_and_test(atomic_t *v) |
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| 158 | { |
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| 159 | unsigned char c; |
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| 160 | |||
| 161 | __asm__ __volatile__( |
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| 162 | LOCK "incl %0; sete %1" |
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| 163 | :"=m" (v->counter), "=qm" (c) |
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| 164 | :"m" (v->counter) : "memory"); |
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| 165 | return c != 0; |
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| 166 | } |
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| 167 | |||
| 168 | /** |
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| 169 | * atomic_add_negative - add and test if negative |
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| 170 | * @v: pointer of type atomic_t |
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| 171 | * @i: integer value to add |
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| 172 | * |
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| 173 | * Atomically adds @i to @v and returns true |
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| 174 | * if the result is negative, or false when |
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| 175 | * result is greater than or equal to zero. Note that the guaranteed |
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| 176 | * useful range of an atomic_t is only 24 bits. |
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| 177 | */ |
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| 178 | static __inline__ int atomic_add_negative(int i, atomic_t *v) |
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| 179 | { |
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| 180 | unsigned char c; |
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| 181 | |||
| 182 | __asm__ __volatile__( |
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| 183 | LOCK "addl %2,%0; sets %1" |
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| 184 | :"=m" (v->counter), "=qm" (c) |
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| 185 | :"ir" (i), "m" (v->counter) : "memory"); |
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| 186 | return c; |
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| 187 | } |
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| 188 | |||
| 189 | /* These are x86-specific, used by some header files */ |
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| 190 | #define atomic_clear_mask(mask, addr) \ |
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| 191 | __asm__ __volatile__(LOCK "andl %0,%1" \ |
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| 192 | : : "r" (~(mask)),"m" (*addr) : "memory") |
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| 193 | |||
| 194 | #define atomic_set_mask(mask, addr) \ |
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| 195 | __asm__ __volatile__(LOCK "orl %0,%1" \ |
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| 196 | : : "r" (mask),"m" (*(addr)) : "memory") |
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| 197 | |||
| 198 | /* Atomic operations are already serializing on x86 */ |
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| 199 | #define smp_mb__before_atomic_dec() barrier() |
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| 200 | #define smp_mb__after_atomic_dec() barrier() |
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| 201 | #define smp_mb__before_atomic_inc() barrier() |
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| 202 | #define smp_mb__after_atomic_inc() barrier() |
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| 203 | |||
| 204 | #endif |