arch/x86/include/asm/atomic.h

   1 #ifndef _ASM_X86_ATOMIC_H
   2 #define _ASM_X86_ATOMIC_H
   3
   4 #include <linux/compiler.h>
   5 #include <linux/types.h>
   6 #include <asm/processor.h>
   7 #include <asm/alternative.h>
   8 #include <asm/cmpxchg.h>
   9
  10 /*
  11  * Atomic operations that C can't guarantee us.  Useful for
  12  * resource counting etc..
  13  */
  14
  15 #define ATOMIC_INIT(i)  { (i) }
  16
  17 /**
  18  * atomic_read - read atomic variable
  19  * @v: pointer of type atomic_t
  20  *
  21  * Atomically reads the value of @v.
  22  */
  23 static inline int atomic_read(const atomic_t *v)
  24 {
  25         return (*(volatile int *)&(v)->counter);
  26 }
  27
  28 /**
  29  * atomic_set - set atomic variable
  30  * @v: pointer of type atomic_t
  31  * @i: required value
  32  *
  33  * Atomically sets the value of @v to @i.
  34  */
  35 static inline void atomic_set(atomic_t *v, int i)
  36 {
  37         v->counter = i;
  38 }
  39
  40 /**
  41  * atomic_add - add integer to atomic variable
  42  * @i: integer value to add
  43  * @v: pointer of type atomic_t
  44  *
  45  * Atomically adds @i to @v.
  46  */
  47 static inline void atomic_add(int i, atomic_t *v)
  48 {
  49         asm volatile(LOCK_PREFIX "addl %1,%0"
  50                      : "+m" (v->counter)
  51                      : "ir" (i));
  52 }
  53
  54 /**
  55  * atomic_sub - subtract integer from atomic variable
  56  * @i: integer value to subtract
  57  * @v: pointer of type atomic_t
  58  *
  59  * Atomically subtracts @i from @v.
  60  */
  61 static inline void atomic_sub(int i, atomic_t *v)
  62 {
  63         asm volatile(LOCK_PREFIX "subl %1,%0"
  64                      : "+m" (v->counter)
  65                      : "ir" (i));
  66 }
  67
  68 /**
  69  * atomic_sub_and_test - subtract value from variable and test result
  70  * @i: integer value to subtract
  71  * @v: pointer of type atomic_t
  72  *
  73  * Atomically subtracts @i from @v and returns
  74  * true if the result is zero, or false for all
  75  * other cases.
  76  */
  77 static inline int atomic_sub_and_test(int i, atomic_t *v)
  78 {
  79         unsigned char c;
  80
  81         asm volatile(LOCK_PREFIX "subl %2,%0; sete %1"
  82                      : "+m" (v->counter), "=qm" (c)
  83                      : "ir" (i) : "memory");
  84         return c;
  85 }
  86
  87 /**
  88  * atomic_inc - increment atomic variable
  89  * @v: pointer of type atomic_t
  90  *
  91  * Atomically increments @v by 1.
  92  */
  93 static inline void atomic_inc(atomic_t *v)
  94 {
  95         asm volatile(LOCK_PREFIX "incl %0"
  96                      : "+m" (v->counter));
  97 }
  98
  99 /**
 100  * atomic_dec - decrement atomic variable
 101  * @v: pointer of type atomic_t
 102  *
 103  * Atomically decrements @v by 1.
 104  */
 105 static inline void atomic_dec(atomic_t *v)
 106 {
 107         asm volatile(LOCK_PREFIX "decl %0"
 108                      : "+m" (v->counter));
 109 }
 110
 111 /**
 112  * atomic_dec_and_test - decrement and test
 113  * @v: pointer of type atomic_t
 114  *
 115  * Atomically decrements @v by 1 and
 116  * returns true if the result is 0, or false for all other
 117  * cases.
 118  */
 119 static inline int atomic_dec_and_test(atomic_t *v)
 120 {
 121         unsigned char c;
 122
 123         asm volatile(LOCK_PREFIX "decl %0; sete %1"
 124                      : "+m" (v->counter), "=qm" (c)
 125                      : : "memory");
 126         return c != 0;
 127 }
 128
 129 /**
 130  * atomic_inc_and_test - increment and test
 131  * @v: pointer of type atomic_t
 132  *
 133  * Atomically increments @v by 1
 134  * and returns true if the result is zero, or false for all
 135  * other cases.
 136  */
 137 static inline int atomic_inc_and_test(atomic_t *v)
 138 {
 139         unsigned char c;
 140
 141         asm volatile(LOCK_PREFIX "incl %0; sete %1"
 142                      : "+m" (v->counter), "=qm" (c)
 143                      : : "memory");
 144         return c != 0;
 145 }
 146
 147 /**
 148  * atomic_add_negative - add and test if negative
 149  * @i: integer value to add
 150  * @v: pointer of type atomic_t
 151  *
 152  * Atomically adds @i to @v and returns true
 153  * if the result is negative, or false when
 154  * result is greater than or equal to zero.
 155  */
 156 static inline int atomic_add_negative(int i, atomic_t *v)
 157 {
 158         unsigned char c;
 159
 160         asm volatile(LOCK_PREFIX "addl %2,%0; sets %1"
 161                      : "+m" (v->counter), "=qm" (c)
 162                      : "ir" (i) : "memory");
 163         return c;
 164 }
 165
 166 /**
 167  * atomic_add_return - add integer and return
 168  * @i: integer value to add
 169  * @v: pointer of type atomic_t
 170  *
 171  * Atomically adds @i to @v and returns @i + @v
 172  */
 173 static inline int atomic_add_return(int i, atomic_t *v)
 174 {
 175         int __i;
 176 #ifdef CONFIG_M386
 177         unsigned long flags;
 178         if (unlikely(boot_cpu_data.x86 <= 3))
 179                 goto no_xadd;
 180 #endif
 181         /* Modern 486+ processor */
 182         __i = i;
 183         asm volatile(LOCK_PREFIX "xaddl %0, %1"
 184                      : "+r" (i), "+m" (v->counter)
 185                      : : "memory");
 186         return i + __i;
 187
 188 #ifdef CONFIG_M386
 189 no_xadd: /* Legacy 386 processor */
 190         raw_local_irq_save(flags);
 191         __i = atomic_read(v);
 192         atomic_set(v, i + __i);
 193         raw_local_irq_restore(flags);
 194         return i + __i;
 195 #endif
 196 }
 197
 198 /**
 199  * atomic_sub_return - subtract integer and return
 200  * @v: pointer of type atomic_t
 201  * @i: integer value to subtract
 202  *
 203  * Atomically subtracts @i from @v and returns @v - @i
 204  */
 205 static inline int atomic_sub_return(int i, atomic_t *v)
 206 {
 207         return atomic_add_return(-i, v);
 208 }
 209
 210 #define atomic_inc_return(v)  (atomic_add_return(1, v))
 211 #define atomic_dec_return(v)  (atomic_sub_return(1, v))
 212
 213 static inline int atomic_cmpxchg(atomic_t *v, int old, int new)
 214 {
 215         return cmpxchg(&v->counter, old, new);
 216 }
 217
 218 static inline int atomic_xchg(atomic_t *v, int new)
 219 {
 220         return xchg(&v->counter, new);
 221 }
 222
 223 /**
 224  * atomic_add_unless - add unless the number is already a given value
 225  * @v: pointer of type atomic_t
 226  * @a: the amount to add to v...
 227  * @u: ...unless v is equal to u.
 228  *
 229  * Atomically adds @a to @v, so long as @v was not already @u.
 230  * Returns non-zero if @v was not @u, and zero otherwise.
 231  */
 232 static inline int atomic_add_unless(atomic_t *v, int a, int u)
 233 {
 234         int c, old;
 235         c = atomic_read(v);
 236         for (;;) {
 237                 if (unlikely(c == (u)))
 238                         break;
 239                 old = atomic_cmpxchg((v), c, c + (a));
 240                 if (likely(old == c))
 241                         break;
 242                 c = old;
 243         }
 244         return c != (u);
 245 }
 246
 247
 248 /*
 249  * atomic_dec_if_positive - decrement by 1 if old value positive
 250  * @v: pointer of type atomic_t
 251  *
 252  * The function returns the old value of *v minus 1, even if
 253  * the atomic variable, v, was not decremented.
 254  */
 255 static inline int atomic_dec_if_positive(atomic_t *v)
 256 {
 257         int c, old, dec;
 258         c = atomic_read(v);
 259         for (;;) {
 260                 dec = c - 1;
 261                 if (unlikely(dec < 0))
 262                         break;
 263                 old = atomic_cmpxchg((v), c, dec);
 264                 if (likely(old == c))
 265                         break;
 266                 c = old;
 267         }
 268         return dec;
 269 }
 270
 271 /**
 272  * atomic_inc_short - increment of a short integer
 273  * @v: pointer to type int
 274  *
 275  * Atomically adds 1 to @v
 276  * Returns the new value of @u
 277  */
 278 static inline short int atomic_inc_short(short int *v)
 279 {
 280         asm(LOCK_PREFIX "addw $1, %0" : "+m" (*v));
 281         return *v;
 282 }
 283
 284 #ifdef CONFIG_X86_64
 285 /**
 286  * atomic_or_long - OR of two long integers
 287  * @v1: pointer to type unsigned long
 288  * @v2: pointer to type unsigned long
 289  *
 290  * Atomically ORs @v1 and @v2
 291  * Returns the result of the OR
 292  */
 293 static inline void atomic_or_long(unsigned long *v1, unsigned long v2)
 294 {
 295         asm(LOCK_PREFIX "orq %1, %0" : "+m" (*v1) : "r" (v2));
 296 }
 297 #endif
 298
 299 /* These are x86-specific, used by some header files */
 300 #define atomic_clear_mask(mask, addr)                           \
 301         asm volatile(LOCK_PREFIX "andl %0,%1"                   \
 302                      : : "r" (~(mask)), "m" (*(addr)) : "memory")
 303
 304 #define atomic_set_mask(mask, addr)                             \
 305         asm volatile(LOCK_PREFIX "orl %0,%1"                    \
 306                      : : "r" ((unsigned)(mask)), "m" (*(addr))  \
 307                      : "memory")
 308
 309 /* Atomic operations are already serializing on x86 */
 310 #define smp_mb__before_atomic_dec()     barrier()
 311 #define smp_mb__after_atomic_dec()      barrier()
 312 #define smp_mb__before_atomic_inc()     barrier()
 313 #define smp_mb__after_atomic_inc()      barrier()
 314
 315 #ifdef CONFIG_X86_32
 316 # include "atomic64_32.h"
 317 #else
 318 # include "atomic64_64.h"
 319 #endif
 320
 321 #include <asm-generic/atomic-long.h>
 322 #endif /* _ASM_X86_ATOMIC_H */