Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1 | #ifndef __ARCH_I386_ATOMIC__ |
| 2 | #define __ARCH_I386_ATOMIC__ |
| 3 | |
| 4 | #include <linux/config.h> |
| 5 | #include <linux/compiler.h> |
| 6 | #include <asm/processor.h> |
| 7 | |
| 8 | /* |
| 9 | * Atomic operations that C can't guarantee us. Useful for |
| 10 | * resource counting etc.. |
| 11 | */ |
| 12 | |
| 13 | #ifdef CONFIG_SMP |
| 14 | #define LOCK "lock ; " |
| 15 | #else |
| 16 | #define LOCK "" |
| 17 | #endif |
| 18 | |
| 19 | /* |
| 20 | * Make sure gcc doesn't try to be clever and move things around |
| 21 | * on us. We need to use _exactly_ the address the user gave us, |
| 22 | * not some alias that contains the same information. |
| 23 | */ |
| 24 | typedef struct { volatile int counter; } atomic_t; |
| 25 | |
| 26 | #define ATOMIC_INIT(i) { (i) } |
| 27 | |
| 28 | /** |
| 29 | * atomic_read - read atomic variable |
| 30 | * @v: pointer of type atomic_t |
| 31 | * |
| 32 | * Atomically reads the value of @v. |
| 33 | */ |
| 34 | #define atomic_read(v) ((v)->counter) |
| 35 | |
| 36 | /** |
| 37 | * atomic_set - set atomic variable |
| 38 | * @v: pointer of type atomic_t |
| 39 | * @i: required value |
| 40 | * |
| 41 | * Atomically sets the value of @v to @i. |
| 42 | */ |
| 43 | #define atomic_set(v,i) (((v)->counter) = (i)) |
| 44 | |
| 45 | /** |
| 46 | * atomic_add - add integer to atomic variable |
| 47 | * @i: integer value to add |
| 48 | * @v: pointer of type atomic_t |
| 49 | * |
| 50 | * Atomically adds @i to @v. |
| 51 | */ |
| 52 | static __inline__ void atomic_add(int i, atomic_t *v) |
| 53 | { |
| 54 | __asm__ __volatile__( |
| 55 | LOCK "addl %1,%0" |
| 56 | :"=m" (v->counter) |
| 57 | :"ir" (i), "m" (v->counter)); |
| 58 | } |
| 59 | |
| 60 | /** |
| 61 | * atomic_sub - subtract the atomic variable |
| 62 | * @i: integer value to subtract |
| 63 | * @v: pointer of type atomic_t |
| 64 | * |
| 65 | * Atomically subtracts @i from @v. |
| 66 | */ |
| 67 | static __inline__ void atomic_sub(int i, atomic_t *v) |
| 68 | { |
| 69 | __asm__ __volatile__( |
| 70 | LOCK "subl %1,%0" |
| 71 | :"=m" (v->counter) |
| 72 | :"ir" (i), "m" (v->counter)); |
| 73 | } |
| 74 | |
| 75 | /** |
| 76 | * atomic_sub_and_test - subtract value from variable and test result |
| 77 | * @i: integer value to subtract |
| 78 | * @v: pointer of type atomic_t |
| 79 | * |
| 80 | * Atomically subtracts @i from @v and returns |
| 81 | * true if the result is zero, or false for all |
| 82 | * other cases. |
| 83 | */ |
| 84 | static __inline__ int atomic_sub_and_test(int i, atomic_t *v) |
| 85 | { |
| 86 | unsigned char c; |
| 87 | |
| 88 | __asm__ __volatile__( |
| 89 | LOCK "subl %2,%0; sete %1" |
| 90 | :"=m" (v->counter), "=qm" (c) |
| 91 | :"ir" (i), "m" (v->counter) : "memory"); |
| 92 | return c; |
| 93 | } |
| 94 | |
| 95 | /** |
| 96 | * atomic_inc - increment atomic variable |
| 97 | * @v: pointer of type atomic_t |
| 98 | * |
| 99 | * Atomically increments @v by 1. |
| 100 | */ |
| 101 | static __inline__ void atomic_inc(atomic_t *v) |
| 102 | { |
| 103 | __asm__ __volatile__( |
| 104 | LOCK "incl %0" |
| 105 | :"=m" (v->counter) |
| 106 | :"m" (v->counter)); |
| 107 | } |
| 108 | |
| 109 | /** |
| 110 | * atomic_dec - decrement atomic variable |
| 111 | * @v: pointer of type atomic_t |
| 112 | * |
| 113 | * Atomically decrements @v by 1. |
| 114 | */ |
| 115 | static __inline__ void atomic_dec(atomic_t *v) |
| 116 | { |
| 117 | __asm__ __volatile__( |
| 118 | LOCK "decl %0" |
| 119 | :"=m" (v->counter) |
| 120 | :"m" (v->counter)); |
| 121 | } |
| 122 | |
| 123 | /** |
| 124 | * atomic_dec_and_test - decrement and test |
| 125 | * @v: pointer of type atomic_t |
| 126 | * |
| 127 | * Atomically decrements @v by 1 and |
| 128 | * returns true if the result is 0, or false for all other |
| 129 | * cases. |
| 130 | */ |
| 131 | static __inline__ int atomic_dec_and_test(atomic_t *v) |
| 132 | { |
| 133 | unsigned char c; |
| 134 | |
| 135 | __asm__ __volatile__( |
| 136 | LOCK "decl %0; sete %1" |
| 137 | :"=m" (v->counter), "=qm" (c) |
| 138 | :"m" (v->counter) : "memory"); |
| 139 | return c != 0; |
| 140 | } |
| 141 | |
| 142 | /** |
| 143 | * atomic_inc_and_test - increment and test |
| 144 | * @v: pointer of type atomic_t |
| 145 | * |
| 146 | * Atomically increments @v by 1 |
| 147 | * and returns true if the result is zero, or false for all |
| 148 | * other cases. |
| 149 | */ |
| 150 | static __inline__ int atomic_inc_and_test(atomic_t *v) |
| 151 | { |
| 152 | unsigned char c; |
| 153 | |
| 154 | __asm__ __volatile__( |
| 155 | LOCK "incl %0; sete %1" |
| 156 | :"=m" (v->counter), "=qm" (c) |
| 157 | :"m" (v->counter) : "memory"); |
| 158 | return c != 0; |
| 159 | } |
| 160 | |
| 161 | /** |
| 162 | * atomic_add_negative - add and test if negative |
| 163 | * @v: pointer of type atomic_t |
| 164 | * @i: integer value to add |
| 165 | * |
| 166 | * Atomically adds @i to @v and returns true |
| 167 | * if the result is negative, or false when |
| 168 | * result is greater than or equal to zero. |
| 169 | */ |
| 170 | static __inline__ int atomic_add_negative(int i, atomic_t *v) |
| 171 | { |
| 172 | unsigned char c; |
| 173 | |
| 174 | __asm__ __volatile__( |
| 175 | LOCK "addl %2,%0; sets %1" |
| 176 | :"=m" (v->counter), "=qm" (c) |
| 177 | :"ir" (i), "m" (v->counter) : "memory"); |
| 178 | return c; |
| 179 | } |
| 180 | |
| 181 | /** |
| 182 | * atomic_add_return - add and return |
| 183 | * @v: pointer of type atomic_t |
| 184 | * @i: integer value to add |
| 185 | * |
| 186 | * Atomically adds @i to @v and returns @i + @v |
| 187 | */ |
| 188 | static __inline__ int atomic_add_return(int i, atomic_t *v) |
| 189 | { |
| 190 | int __i; |
| 191 | #ifdef CONFIG_M386 |
| 192 | if(unlikely(boot_cpu_data.x86==3)) |
| 193 | goto no_xadd; |
| 194 | #endif |
| 195 | /* Modern 486+ processor */ |
| 196 | __i = i; |
| 197 | __asm__ __volatile__( |
| 198 | LOCK "xaddl %0, %1;" |
| 199 | :"=r"(i) |
| 200 | :"m"(v->counter), "0"(i)); |
| 201 | return i + __i; |
| 202 | |
| 203 | #ifdef CONFIG_M386 |
| 204 | no_xadd: /* Legacy 386 processor */ |
| 205 | local_irq_disable(); |
| 206 | __i = atomic_read(v); |
| 207 | atomic_set(v, i + __i); |
| 208 | local_irq_enable(); |
| 209 | return i + __i; |
| 210 | #endif |
| 211 | } |
| 212 | |
| 213 | static __inline__ int atomic_sub_return(int i, atomic_t *v) |
| 214 | { |
| 215 | return atomic_add_return(-i,v); |
| 216 | } |
| 217 | |
Nick Piggin | 4a6dae6 | 2005-11-13 16:07:24 -0800 | [diff] [blame^] | 218 | #define atomic_cmpxchg(v, old, new) ((int)cmpxchg(&((v)->counter), old, new)) |
| 219 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 220 | #define atomic_inc_return(v) (atomic_add_return(1,v)) |
| 221 | #define atomic_dec_return(v) (atomic_sub_return(1,v)) |
| 222 | |
| 223 | /* These are x86-specific, used by some header files */ |
| 224 | #define atomic_clear_mask(mask, addr) \ |
| 225 | __asm__ __volatile__(LOCK "andl %0,%1" \ |
| 226 | : : "r" (~(mask)),"m" (*addr) : "memory") |
| 227 | |
| 228 | #define atomic_set_mask(mask, addr) \ |
| 229 | __asm__ __volatile__(LOCK "orl %0,%1" \ |
| 230 | : : "r" (mask),"m" (*(addr)) : "memory") |
| 231 | |
| 232 | /* Atomic operations are already serializing on x86 */ |
| 233 | #define smp_mb__before_atomic_dec() barrier() |
| 234 | #define smp_mb__after_atomic_dec() barrier() |
| 235 | #define smp_mb__before_atomic_inc() barrier() |
| 236 | #define smp_mb__after_atomic_inc() barrier() |
| 237 | |
| 238 | #endif |