include/linux/atomic.h

   1 /* Atomic operations usable in machine independent code */
   2 #ifndef _LINUX_ATOMIC_H
   3 #define _LINUX_ATOMIC_H
   4 #include <asm/atomic.h>
   5 #include <asm/barrier.h>
   6
   7 /*
   8  * Relaxed variants of xchg, cmpxchg and some atomic operations.
   9  *
  10  * We support four variants:
  11  *
  12  * - Fully ordered: The default implementation, no suffix required.
  13  * - Acquire: Provides ACQUIRE semantics, _acquire suffix.
  14  * - Release: Provides RELEASE semantics, _release suffix.
  15  * - Relaxed: No ordering guarantees, _relaxed suffix.
  16  *
  17  * For compound atomics performing both a load and a store, ACQUIRE
  18  * semantics apply only to the load and RELEASE semantics only to the
  19  * store portion of the operation. Note that a failed cmpxchg_acquire
  20  * does -not- imply any memory ordering constraints.
  21  *
  22  * See Documentation/memory-barriers.txt for ACQUIRE/RELEASE definitions.
  23  */
  24
  25 #ifndef atomic_read_acquire
  26 #define  atomic_read_acquire(v)         smp_load_acquire(&(v)->counter)
  27 #endif
  28
  29 #ifndef atomic_set_release
  30 #define  atomic_set_release(v, i)       smp_store_release(&(v)->counter, (i))
  31 #endif
  32
  33 /*
  34  * The idea here is to build acquire/release variants by adding explicit
  35  * barriers on top of the relaxed variant. In the case where the relaxed
  36  * variant is already fully ordered, no additional barriers are needed.
  37  */
  38 #define __atomic_op_acquire(op, args...)                                \
  39 ({                                                                      \
  40         typeof(op##_relaxed(args)) __ret  = op##_relaxed(args);         \
  41         smp_mb__after_atomic();                                         \
  42         __ret;                                                          \
  43 })
  44
  45 #define __atomic_op_release(op, args...)                                \
  46 ({                                                                      \
  47         smp_mb__before_atomic();                                        \
  48         op##_relaxed(args);                                             \
  49 })
  50
  51 #define __atomic_op_fence(op, args...)                                  \
  52 ({                                                                      \
  53         typeof(op##_relaxed(args)) __ret;                               \
  54         smp_mb__before_atomic();                                        \
  55         __ret = op##_relaxed(args);                                     \
  56         smp_mb__after_atomic();                                         \
  57         __ret;                                                          \
  58 })
  59
  60 /* atomic_add_return_relaxed */
  61 #ifndef atomic_add_return_relaxed
  62 #define  atomic_add_return_relaxed      atomic_add_return
  63 #define  atomic_add_return_acquire      atomic_add_return
  64 #define  atomic_add_return_release      atomic_add_return
  65
  66 #else /* atomic_add_return_relaxed */
  67
  68 #ifndef atomic_add_return_acquire
  69 #define  atomic_add_return_acquire(...)                                 \
  70         __atomic_op_acquire(atomic_add_return, __VA_ARGS__)
  71 #endif
  72
  73 #ifndef atomic_add_return_release
  74 #define  atomic_add_return_release(...)                                 \
  75         __atomic_op_release(atomic_add_return, __VA_ARGS__)
  76 #endif
  77
  78 #ifndef atomic_add_return
  79 #define  atomic_add_return(...)                                         \
  80         __atomic_op_fence(atomic_add_return, __VA_ARGS__)
  81 #endif
  82 #endif /* atomic_add_return_relaxed */
  83
  84 /* atomic_sub_return_relaxed */
  85 #ifndef atomic_sub_return_relaxed
  86 #define  atomic_sub_return_relaxed      atomic_sub_return
  87 #define  atomic_sub_return_acquire      atomic_sub_return
  88 #define  atomic_sub_return_release      atomic_sub_return
  89
  90 #else /* atomic_sub_return_relaxed */
  91
  92 #ifndef atomic_sub_return_acquire
  93 #define  atomic_sub_return_acquire(...)                                 \
  94         __atomic_op_acquire(atomic_sub_return, __VA_ARGS__)
  95 #endif
  96
  97 #ifndef atomic_sub_return_release
  98 #define  atomic_sub_return_release(...)                                 \
  99         __atomic_op_release(atomic_sub_return, __VA_ARGS__)
 100 #endif
 101
 102 #ifndef atomic_sub_return
 103 #define  atomic_sub_return(...)                                         \
 104         __atomic_op_fence(atomic_sub_return, __VA_ARGS__)
 105 #endif
 106 #endif /* atomic_sub_return_relaxed */
 107
 108 /* atomic_xchg_relaxed */
 109 #ifndef atomic_xchg_relaxed
 110 #define  atomic_xchg_relaxed            atomic_xchg
 111 #define  atomic_xchg_acquire            atomic_xchg
 112 #define  atomic_xchg_release            atomic_xchg
 113
 114 #else /* atomic_xchg_relaxed */
 115
 116 #ifndef atomic_xchg_acquire
 117 #define  atomic_xchg_acquire(...)                                       \
 118         __atomic_op_acquire(atomic_xchg, __VA_ARGS__)
 119 #endif
 120
 121 #ifndef atomic_xchg_release
 122 #define  atomic_xchg_release(...)                                       \
 123         __atomic_op_release(atomic_xchg, __VA_ARGS__)
 124 #endif
 125
 126 #ifndef atomic_xchg
 127 #define  atomic_xchg(...)                                               \
 128         __atomic_op_fence(atomic_xchg, __VA_ARGS__)
 129 #endif
 130 #endif /* atomic_xchg_relaxed */
 131
 132 /* atomic_cmpxchg_relaxed */
 133 #ifndef atomic_cmpxchg_relaxed
 134 #define  atomic_cmpxchg_relaxed         atomic_cmpxchg
 135 #define  atomic_cmpxchg_acquire         atomic_cmpxchg
 136 #define  atomic_cmpxchg_release         atomic_cmpxchg
 137
 138 #else /* atomic_cmpxchg_relaxed */
 139
 140 #ifndef atomic_cmpxchg_acquire
 141 #define  atomic_cmpxchg_acquire(...)                                    \
 142         __atomic_op_acquire(atomic_cmpxchg, __VA_ARGS__)
 143 #endif
 144
 145 #ifndef atomic_cmpxchg_release
 146 #define  atomic_cmpxchg_release(...)                                    \
 147         __atomic_op_release(atomic_cmpxchg, __VA_ARGS__)
 148 #endif
 149
 150 #ifndef atomic_cmpxchg
 151 #define  atomic_cmpxchg(...)                                            \
 152         __atomic_op_fence(atomic_cmpxchg, __VA_ARGS__)
 153 #endif
 154 #endif /* atomic_cmpxchg_relaxed */
 155
 156 #ifndef atomic64_read_acquire
 157 #define  atomic64_read_acquire(v)       smp_load_acquire(&(v)->counter)
 158 #endif
 159
 160 #ifndef atomic64_set_release
 161 #define  atomic64_set_release(v, i)     smp_store_release(&(v)->counter, (i))
 162 #endif
 163
 164 /* atomic64_add_return_relaxed */
 165 #ifndef atomic64_add_return_relaxed
 166 #define  atomic64_add_return_relaxed    atomic64_add_return
 167 #define  atomic64_add_return_acquire    atomic64_add_return
 168 #define  atomic64_add_return_release    atomic64_add_return
 169
 170 #else /* atomic64_add_return_relaxed */
 171
 172 #ifndef atomic64_add_return_acquire
 173 #define  atomic64_add_return_acquire(...)                               \
 174         __atomic_op_acquire(atomic64_add_return, __VA_ARGS__)
 175 #endif
 176
 177 #ifndef atomic64_add_return_release
 178 #define  atomic64_add_return_release(...)                               \
 179         __atomic_op_release(atomic64_add_return, __VA_ARGS__)
 180 #endif
 181
 182 #ifndef atomic64_add_return
 183 #define  atomic64_add_return(...)                                       \
 184         __atomic_op_fence(atomic64_add_return, __VA_ARGS__)
 185 #endif
 186 #endif /* atomic64_add_return_relaxed */
 187
 188 /* atomic64_sub_return_relaxed */
 189 #ifndef atomic64_sub_return_relaxed
 190 #define  atomic64_sub_return_relaxed    atomic64_sub_return
 191 #define  atomic64_sub_return_acquire    atomic64_sub_return
 192 #define  atomic64_sub_return_release    atomic64_sub_return
 193
 194 #else /* atomic64_sub_return_relaxed */
 195
 196 #ifndef atomic64_sub_return_acquire
 197 #define  atomic64_sub_return_acquire(...)                               \
 198         __atomic_op_acquire(atomic64_sub_return, __VA_ARGS__)
 199 #endif
 200
 201 #ifndef atomic64_sub_return_release
 202 #define  atomic64_sub_return_release(...)                               \
 203         __atomic_op_release(atomic64_sub_return, __VA_ARGS__)
 204 #endif
 205
 206 #ifndef atomic64_sub_return
 207 #define  atomic64_sub_return(...)                                       \
 208         __atomic_op_fence(atomic64_sub_return, __VA_ARGS__)
 209 #endif
 210 #endif /* atomic64_sub_return_relaxed */
 211
 212 /* atomic64_xchg_relaxed */
 213 #ifndef atomic64_xchg_relaxed
 214 #define  atomic64_xchg_relaxed          atomic64_xchg
 215 #define  atomic64_xchg_acquire          atomic64_xchg
 216 #define  atomic64_xchg_release          atomic64_xchg
 217
 218 #else /* atomic64_xchg_relaxed */
 219
 220 #ifndef atomic64_xchg_acquire
 221 #define  atomic64_xchg_acquire(...)                                     \
 222         __atomic_op_acquire(atomic64_xchg, __VA_ARGS__)
 223 #endif
 224
 225 #ifndef atomic64_xchg_release
 226 #define  atomic64_xchg_release(...)                                     \
 227         __atomic_op_release(atomic64_xchg, __VA_ARGS__)
 228 #endif
 229
 230 #ifndef atomic64_xchg
 231 #define  atomic64_xchg(...)                                             \
 232         __atomic_op_fence(atomic64_xchg, __VA_ARGS__)
 233 #endif
 234 #endif /* atomic64_xchg_relaxed */
 235
 236 /* atomic64_cmpxchg_relaxed */
 237 #ifndef atomic64_cmpxchg_relaxed
 238 #define  atomic64_cmpxchg_relaxed       atomic64_cmpxchg
 239 #define  atomic64_cmpxchg_acquire       atomic64_cmpxchg
 240 #define  atomic64_cmpxchg_release       atomic64_cmpxchg
 241
 242 #else /* atomic64_cmpxchg_relaxed */
 243
 244 #ifndef atomic64_cmpxchg_acquire
 245 #define  atomic64_cmpxchg_acquire(...)                                  \
 246         __atomic_op_acquire(atomic64_cmpxchg, __VA_ARGS__)
 247 #endif
 248
 249 #ifndef atomic64_cmpxchg_release
 250 #define  atomic64_cmpxchg_release(...)                                  \
 251         __atomic_op_release(atomic64_cmpxchg, __VA_ARGS__)
 252 #endif
 253
 254 #ifndef atomic64_cmpxchg
 255 #define  atomic64_cmpxchg(...)                                          \
 256         __atomic_op_fence(atomic64_cmpxchg, __VA_ARGS__)
 257 #endif
 258 #endif /* atomic64_cmpxchg_relaxed */
 259
 260 /* cmpxchg_relaxed */
 261 #ifndef cmpxchg_relaxed
 262 #define  cmpxchg_relaxed                cmpxchg
 263 #define  cmpxchg_acquire                cmpxchg
 264 #define  cmpxchg_release                cmpxchg
 265
 266 #else /* cmpxchg_relaxed */
 267
 268 #ifndef cmpxchg_acquire
 269 #define  cmpxchg_acquire(...)                                           \
 270         __atomic_op_acquire(cmpxchg, __VA_ARGS__)
 271 #endif
 272
 273 #ifndef cmpxchg_release
 274 #define  cmpxchg_release(...)                                           \
 275         __atomic_op_release(cmpxchg, __VA_ARGS__)
 276 #endif
 277
 278 #ifndef cmpxchg
 279 #define  cmpxchg(...)                                                   \
 280         __atomic_op_fence(cmpxchg, __VA_ARGS__)
 281 #endif
 282 #endif /* cmpxchg_relaxed */
 283
 284 /* cmpxchg64_relaxed */
 285 #ifndef cmpxchg64_relaxed
 286 #define  cmpxchg64_relaxed              cmpxchg64
 287 #define  cmpxchg64_acquire              cmpxchg64
 288 #define  cmpxchg64_release              cmpxchg64
 289
 290 #else /* cmpxchg64_relaxed */
 291
 292 #ifndef cmpxchg64_acquire
 293 #define  cmpxchg64_acquire(...)                                         \
 294         __atomic_op_acquire(cmpxchg64, __VA_ARGS__)
 295 #endif
 296
 297 #ifndef cmpxchg64_release
 298 #define  cmpxchg64_release(...)                                         \
 299         __atomic_op_release(cmpxchg64, __VA_ARGS__)
 300 #endif
 301
 302 #ifndef cmpxchg64
 303 #define  cmpxchg64(...)                                                 \
 304         __atomic_op_fence(cmpxchg64, __VA_ARGS__)
 305 #endif
 306 #endif /* cmpxchg64_relaxed */
 307
 308 /* xchg_relaxed */
 309 #ifndef xchg_relaxed
 310 #define  xchg_relaxed                   xchg
 311 #define  xchg_acquire                   xchg
 312 #define  xchg_release                   xchg
 313
 314 #else /* xchg_relaxed */
 315
 316 #ifndef xchg_acquire
 317 #define  xchg_acquire(...)              __atomic_op_acquire(xchg, __VA_ARGS__)
 318 #endif
 319
 320 #ifndef xchg_release
 321 #define  xchg_release(...)              __atomic_op_release(xchg, __VA_ARGS__)
 322 #endif
 323
 324 #ifndef xchg
 325 #define  xchg(...)                      __atomic_op_fence(xchg, __VA_ARGS__)
 326 #endif
 327 #endif /* xchg_relaxed */
 328
 329 /**
 330  * atomic_add_unless - add unless the number is already a given value
 331  * @v: pointer of type atomic_t
 332  * @a: the amount to add to v...
 333  * @u: ...unless v is equal to u.
 334  *
 335  * Atomically adds @a to @v, so long as @v was not already @u.
 336  * Returns non-zero if @v was not @u, and zero otherwise.
 337  */
 338 static inline int atomic_add_unless(atomic_t *v, int a, int u)
 339 {
 340         return __atomic_add_unless(v, a, u) != u;
 341 }
 342
 343 /**
 344  * atomic_inc_not_zero - increment unless the number is zero
 345  * @v: pointer of type atomic_t
 346  *
 347  * Atomically increments @v by 1, so long as @v is non-zero.
 348  * Returns non-zero if @v was non-zero, and zero otherwise.
 349  */
 350 #ifndef atomic_inc_not_zero
 351 #define atomic_inc_not_zero(v)          atomic_add_unless((v), 1, 0)
 352 #endif
 353
 354 #ifndef atomic_andnot
 355 static inline void atomic_andnot(int i, atomic_t *v)
 356 {
 357         atomic_and(~i, v);
 358 }
 359 #endif
 360
 361 static inline __deprecated void atomic_clear_mask(unsigned int mask, atomic_t *v)
 362 {
 363         atomic_andnot(mask, v);
 364 }
 365
 366 static inline __deprecated void atomic_set_mask(unsigned int mask, atomic_t *v)
 367 {
 368         atomic_or(mask, v);
 369 }
 370
 371 /**
 372  * atomic_inc_not_zero_hint - increment if not null
 373  * @v: pointer of type atomic_t
 374  * @hint: probable value of the atomic before the increment
 375  *
 376  * This version of atomic_inc_not_zero() gives a hint of probable
 377  * value of the atomic. This helps processor to not read the memory
 378  * before doing the atomic read/modify/write cycle, lowering
 379  * number of bus transactions on some arches.
 380  *
 381  * Returns: 0 if increment was not done, 1 otherwise.
 382  */
 383 #ifndef atomic_inc_not_zero_hint
 384 static inline int atomic_inc_not_zero_hint(atomic_t *v, int hint)
 385 {
 386         int val, c = hint;
 387
 388         /* sanity test, should be removed by compiler if hint is a constant */
 389         if (!hint)
 390                 return atomic_inc_not_zero(v);
 391
 392         do {
 393                 val = atomic_cmpxchg(v, c, c + 1);
 394                 if (val == c)
 395                         return 1;
 396                 c = val;
 397         } while (c);
 398
 399         return 0;
 400 }
 401 #endif
 402
 403 #ifndef atomic_inc_unless_negative
 404 static inline int atomic_inc_unless_negative(atomic_t *p)
 405 {
 406         int v, v1;
 407         for (v = 0; v >= 0; v = v1) {
 408                 v1 = atomic_cmpxchg(p, v, v + 1);
 409                 if (likely(v1 == v))
 410                         return 1;
 411         }
 412         return 0;
 413 }
 414 #endif
 415
 416 #ifndef atomic_dec_unless_positive
 417 static inline int atomic_dec_unless_positive(atomic_t *p)
 418 {
 419         int v, v1;
 420         for (v = 0; v <= 0; v = v1) {
 421                 v1 = atomic_cmpxchg(p, v, v - 1);
 422                 if (likely(v1 == v))
 423                         return 1;
 424         }
 425         return 0;
 426 }
 427 #endif
 428
 429 /*
 430  * atomic_dec_if_positive - decrement by 1 if old value positive
 431  * @v: pointer of type atomic_t
 432  *
 433  * The function returns the old value of *v minus 1, even if
 434  * the atomic variable, v, was not decremented.
 435  */
 436 #ifndef atomic_dec_if_positive
 437 static inline int atomic_dec_if_positive(atomic_t *v)
 438 {
 439         int c, old, dec;
 440         c = atomic_read(v);
 441         for (;;) {
 442                 dec = c - 1;
 443                 if (unlikely(dec < 0))
 444                         break;
 445                 old = atomic_cmpxchg((v), c, dec);
 446                 if (likely(old == c))
 447                         break;
 448                 c = old;
 449         }
 450         return dec;
 451 }
 452 #endif
 453
 454 #include <asm-generic/atomic-long.h>
 455 #ifdef CONFIG_GENERIC_ATOMIC64
 456 #include <asm-generic/atomic64.h>
 457 #endif
 458
 459 #ifndef atomic64_andnot
 460 static inline void atomic64_andnot(long long i, atomic64_t *v)
 461 {
 462         atomic64_and(~i, v);
 463 }
 464 #endif
 465
 466 #endif /* _LINUX_ATOMIC_H */