kernel/include/linux/spinlock.h

   1 #ifndef __LINUX_SPINLOCK_H
   2 #define __LINUX_SPINLOCK_H
   3
   4 /*
   5  * include/linux/spinlock.h - generic spinlock/rwlock declarations
   6  *
   7  * here's the role of the various spinlock/rwlock related include files:
   8  *
   9  * on SMP builds:
  10  *
  11  *  asm/spinlock_types.h: contains the arch_spinlock_t/arch_rwlock_t and the
  12  *                        initializers
  13  *
  14  *  linux/spinlock_types.h:
  15  *                        defines the generic type and initializers
  16  *
  17  *  asm/spinlock.h:       contains the arch_spin_*()/etc. lowlevel
  18  *                        implementations, mostly inline assembly code
  19  *
  20  *   (also included on UP-debug builds:)
  21  *
  22  *  linux/spinlock_api_smp.h:
  23  *                        contains the prototypes for the _spin_*() APIs.
  24  *
  25  *  linux/spinlock.h:     builds the final spin_*() APIs.
  26  *
  27  * on UP builds:
  28  *
  29  *  linux/spinlock_type_up.h:
  30  *                        contains the generic, simplified UP spinlock type.
  31  *                        (which is an empty structure on non-debug builds)
  32  *
  33  *  linux/spinlock_types.h:
  34  *                        defines the generic type and initializers
  35  *
  36  *  linux/spinlock_up.h:
  37  *                        contains the arch_spin_*()/etc. version of UP
  38  *                        builds. (which are NOPs on non-debug, non-preempt
  39  *                        builds)
  40  *
  41  *   (included on UP-non-debug builds:)
  42  *
  43  *  linux/spinlock_api_up.h:
  44  *                        builds the _spin_*() APIs.
  45  *
  46  *  linux/spinlock.h:     builds the final spin_*() APIs.
  47  */
  48
  49 #include <linux/typecheck.h>
  50 #include <linux/preempt.h>
  51 #include <linux/linkage.h>
  52 #include <linux/compiler.h>
  53 #include <linux/irqflags.h>
  54 #include <linux/thread_info.h>
  55 #include <linux/kernel.h>
  56 #include <linux/stringify.h>
  57 #include <linux/bottom_half.h>
  58 #include <asm/barrier.h>
  59
  60
  61 /*
  62  * Must define these before including other files, inline functions need them
  63  */
  64 #define LOCK_SECTION_NAME ".text..lock."KBUILD_BASENAME
  65
  66 #define LOCK_SECTION_START(extra)               \
  67         ".subsection 1\n\t"                     \
  68         extra                                   \
  69         ".ifndef " LOCK_SECTION_NAME "\n\t"     \
  70         LOCK_SECTION_NAME ":\n\t"               \
  71         ".endif\n"
  72
  73 #define LOCK_SECTION_END                        \
  74         ".previous\n\t"
  75
  76 #define __lockfunc __attribute__((section(".spinlock.text")))
  77
  78 /*
  79  * Pull the arch_spinlock_t and arch_rwlock_t definitions:
  80  */
  81 #include <linux/spinlock_types.h>
  82
  83 /*
  84  * Pull the arch_spin*() functions/declarations (UP-nondebug doesn't need them):
  85  */
  86 #ifdef CONFIG_SMP
  87 # include <asm/spinlock.h>
  88 #else
  89 # include <linux/spinlock_up.h>
  90 #endif
  91
  92 #ifdef CONFIG_DEBUG_SPINLOCK
  93   extern void __raw_spin_lock_init(raw_spinlock_t *lock, const char *name,
  94                                    struct lock_class_key *key);
  95 # define raw_spin_lock_init(lock)                               \
  96 do {                                                            \
  97         static struct lock_class_key __key;                     \
  98                                                                 \
  99         __raw_spin_lock_init((lock), #lock, &__key);            \
 100 } while (0)
 101
 102 #else
 103 # define raw_spin_lock_init(lock)                               \
 104         do { *(lock) = __RAW_SPIN_LOCK_UNLOCKED(lock); } while (0)
 105 #endif
 106
 107 #define raw_spin_is_locked(lock)        arch_spin_is_locked(&(lock)->raw_lock)
 108
 109 #ifdef CONFIG_GENERIC_LOCKBREAK
 110 #define raw_spin_is_contended(lock) ((lock)->break_lock)
 111 #else
 112
 113 #ifdef arch_spin_is_contended
 114 #define raw_spin_is_contended(lock)     arch_spin_is_contended(&(lock)->raw_lock)
 115 #else
 116 #define raw_spin_is_contended(lock)     (((void)(lock), 0))
 117 #endif /*arch_spin_is_contended*/
 118 #endif
 119
 120 /*
 121  * Despite its name it doesn't necessarily has to be a full barrier.
 122  * It should only guarantee that a STORE before the critical section
 123  * can not be reordered with a LOAD inside this section.
 124  * spin_lock() is the one-way barrier, this LOAD can not escape out
 125  * of the region. So the default implementation simply ensures that
 126  * a STORE can not move into the critical section, smp_wmb() should
 127  * serialize it with another STORE done by spin_lock().
 128  */
 129 #ifndef smp_mb__before_spinlock
 130 #define smp_mb__before_spinlock()       smp_wmb()
 131 #endif
 132
 133 /*
 134  * Place this after a lock-acquisition primitive to guarantee that
 135  * an UNLOCK+LOCK pair act as a full barrier.  This guarantee applies
 136  * if the UNLOCK and LOCK are executed by the same CPU or if the
 137  * UNLOCK and LOCK operate on the same lock variable.
 138  */
 139 #ifndef smp_mb__after_unlock_lock
 140 #define smp_mb__after_unlock_lock()     do { } while (0)
 141 #endif
 142
 143 /**
 144  * raw_spin_unlock_wait - wait until the spinlock gets unlocked
 145  * @lock: the spinlock in question.
 146  */
 147 #define raw_spin_unlock_wait(lock)      arch_spin_unlock_wait(&(lock)->raw_lock)
 148
 149 #ifdef CONFIG_DEBUG_SPINLOCK
 150  extern void do_raw_spin_lock(raw_spinlock_t *lock) __acquires(lock);
 151 #define do_raw_spin_lock_flags(lock, flags) do_raw_spin_lock(lock)
 152  extern int do_raw_spin_trylock(raw_spinlock_t *lock);
 153  extern void do_raw_spin_unlock(raw_spinlock_t *lock) __releases(lock);
 154 #else
 155 static inline void do_raw_spin_lock(raw_spinlock_t *lock) __acquires(lock)
 156 {
 157         __acquire(lock);
 158         arch_spin_lock(&lock->raw_lock);
 159 }
 160
 161 static inline void
 162 do_raw_spin_lock_flags(raw_spinlock_t *lock, unsigned long *flags) __acquires(lock)
 163 {
 164         __acquire(lock);
 165         arch_spin_lock_flags(&lock->raw_lock, *flags);
 166 }
 167
 168 static inline int do_raw_spin_trylock(raw_spinlock_t *lock)
 169 {
 170         return arch_spin_trylock(&(lock)->raw_lock);
 171 }
 172
 173 static inline void do_raw_spin_unlock(raw_spinlock_t *lock) __releases(lock)
 174 {
 175         arch_spin_unlock(&lock->raw_lock);
 176         __release(lock);
 177 }
 178 #endif
 179
 180 /*
 181  * Define the various spin_lock methods.  Note we define these
 182  * regardless of whether CONFIG_SMP or CONFIG_PREEMPT are set. The
 183  * various methods are defined as nops in the case they are not
 184  * required.
 185  */
 186 #define raw_spin_trylock(lock)  __cond_lock(lock, _raw_spin_trylock(lock))
 187
 188 #define raw_spin_lock(lock)     _raw_spin_lock(lock)
 189
 190 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 191 # define raw_spin_lock_nested(lock, subclass) \
 192         _raw_spin_lock_nested(lock, subclass)
 193 # define raw_spin_lock_bh_nested(lock, subclass) \
 194         _raw_spin_lock_bh_nested(lock, subclass)
 195
 196 # define raw_spin_lock_nest_lock(lock, nest_lock)                       \
 197          do {                                                           \
 198                  typecheck(struct lockdep_map *, &(nest_lock)->dep_map);\
 199                  _raw_spin_lock_nest_lock(lock, &(nest_lock)->dep_map); \
 200          } while (0)
 201 #else
 202 /*
 203  * Always evaluate the 'subclass' argument to avoid that the compiler
 204  * warns about set-but-not-used variables when building with
 205  * CONFIG_DEBUG_LOCK_ALLOC=n and with W=1.
 206  */
 207 # define raw_spin_lock_nested(lock, subclass)           \
 208         _raw_spin_lock(((void)(subclass), (lock)))
 209 # define raw_spin_lock_nest_lock(lock, nest_lock)       _raw_spin_lock(lock)
 210 # define raw_spin_lock_bh_nested(lock, subclass)        _raw_spin_lock_bh(lock)
 211 #endif
 212
 213 #if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
 214
 215 #define raw_spin_lock_irqsave(lock, flags)                      \
 216         do {                                            \
 217                 typecheck(unsigned long, flags);        \
 218                 flags = _raw_spin_lock_irqsave(lock);   \
 219         } while (0)
 220
 221 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 222 #define raw_spin_lock_irqsave_nested(lock, flags, subclass)             \
 223         do {                                                            \
 224                 typecheck(unsigned long, flags);                        \
 225                 flags = _raw_spin_lock_irqsave_nested(lock, subclass);  \
 226         } while (0)
 227 #else
 228 #define raw_spin_lock_irqsave_nested(lock, flags, subclass)             \
 229         do {                                                            \
 230                 typecheck(unsigned long, flags);                        \
 231                 flags = _raw_spin_lock_irqsave(lock);                   \
 232         } while (0)
 233 #endif
 234
 235 #else
 236
 237 #define raw_spin_lock_irqsave(lock, flags)              \
 238         do {                                            \
 239                 typecheck(unsigned long, flags);        \
 240                 _raw_spin_lock_irqsave(lock, flags);    \
 241         } while (0)
 242
 243 #define raw_spin_lock_irqsave_nested(lock, flags, subclass)     \
 244         raw_spin_lock_irqsave(lock, flags)
 245
 246 #endif
 247
 248 #define raw_spin_lock_irq(lock)         _raw_spin_lock_irq(lock)
 249 #define raw_spin_lock_bh(lock)          _raw_spin_lock_bh(lock)
 250 #define raw_spin_unlock(lock)           _raw_spin_unlock(lock)
 251 #define raw_spin_unlock_irq(lock)       _raw_spin_unlock_irq(lock)
 252
 253 #define raw_spin_unlock_irqrestore(lock, flags)         \
 254         do {                                                    \
 255                 typecheck(unsigned long, flags);                \
 256                 _raw_spin_unlock_irqrestore(lock, flags);       \
 257         } while (0)
 258 #define raw_spin_unlock_bh(lock)        _raw_spin_unlock_bh(lock)
 259
 260 #define raw_spin_trylock_bh(lock) \
 261         __cond_lock(lock, _raw_spin_trylock_bh(lock))
 262
 263 #define raw_spin_trylock_irq(lock) \
 264 ({ \
 265         local_irq_disable(); \
 266         raw_spin_trylock(lock) ? \
 267         1 : ({ local_irq_enable(); 0;  }); \
 268 })
 269
 270 #define raw_spin_trylock_irqsave(lock, flags) \
 271 ({ \
 272         local_irq_save(flags); \
 273         raw_spin_trylock(lock) ? \
 274         1 : ({ local_irq_restore(flags); 0; }); \
 275 })
 276
 277 /**
 278  * raw_spin_can_lock - would raw_spin_trylock() succeed?
 279  * @lock: the spinlock in question.
 280  */
 281 #define raw_spin_can_lock(lock) (!raw_spin_is_locked(lock))
 282
 283 /* Include rwlock functions */
 284 #ifdef CONFIG_PREEMPT_RT_FULL
 285 # include <linux/rwlock_rt.h>
 286 #else
 287 # include <linux/rwlock.h>
 288 #endif
 289
 290 /*
 291  * Pull the _spin_*()/_read_*()/_write_*() functions/declarations:
 292  */
 293 #if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
 294 # include <linux/spinlock_api_smp.h>
 295 #else
 296 # include <linux/spinlock_api_up.h>
 297 #endif
 298
 299 #ifdef CONFIG_PREEMPT_RT_FULL
 300 # include <linux/spinlock_rt.h>
 301 #else /* PREEMPT_RT_FULL */
 302
 303 /*
 304  * Map the spin_lock functions to the raw variants for PREEMPT_RT=n
 305  */
 306
 307 static inline raw_spinlock_t *spinlock_check(spinlock_t *lock)
 308 {
 309         return &lock->rlock;
 310 }
 311
 312 #define spin_lock_init(_lock)                           \
 313 do {                                                    \
 314         spinlock_check(_lock);                          \
 315         raw_spin_lock_init(&(_lock)->rlock);            \
 316 } while (0)
 317
 318 static inline void spin_lock(spinlock_t *lock)
 319 {
 320         raw_spin_lock(&lock->rlock);
 321 }
 322
 323 static inline void spin_lock_bh(spinlock_t *lock)
 324 {
 325         raw_spin_lock_bh(&lock->rlock);
 326 }
 327
 328 static inline int spin_trylock(spinlock_t *lock)
 329 {
 330         return raw_spin_trylock(&lock->rlock);
 331 }
 332
 333 #define spin_lock_nested(lock, subclass)                        \
 334 do {                                                            \
 335         raw_spin_lock_nested(spinlock_check(lock), subclass);   \
 336 } while (0)
 337
 338 #define spin_lock_bh_nested(lock, subclass)                     \
 339 do {                                                            \
 340         raw_spin_lock_bh_nested(spinlock_check(lock), subclass);\
 341 } while (0)
 342
 343 #define spin_lock_nest_lock(lock, nest_lock)                            \
 344 do {                                                                    \
 345         raw_spin_lock_nest_lock(spinlock_check(lock), nest_lock);       \
 346 } while (0)
 347
 348 static inline void spin_lock_irq(spinlock_t *lock)
 349 {
 350         raw_spin_lock_irq(&lock->rlock);
 351 }
 352
 353 #define spin_lock_irqsave(lock, flags)                          \
 354 do {                                                            \
 355         raw_spin_lock_irqsave(spinlock_check(lock), flags);     \
 356 } while (0)
 357
 358 #define spin_lock_irqsave_nested(lock, flags, subclass)                 \
 359 do {                                                                    \
 360         raw_spin_lock_irqsave_nested(spinlock_check(lock), flags, subclass); \
 361 } while (0)
 362
 363 static inline void spin_unlock(spinlock_t *lock)
 364 {
 365         raw_spin_unlock(&lock->rlock);
 366 }
 367
 368 static inline void spin_unlock_bh(spinlock_t *lock)
 369 {
 370         raw_spin_unlock_bh(&lock->rlock);
 371 }
 372
 373 static inline void spin_unlock_irq(spinlock_t *lock)
 374 {
 375         raw_spin_unlock_irq(&lock->rlock);
 376 }
 377
 378 static inline void spin_unlock_irqrestore(spinlock_t *lock, unsigned long flags)
 379 {
 380         raw_spin_unlock_irqrestore(&lock->rlock, flags);
 381 }
 382
 383 static inline int spin_trylock_bh(spinlock_t *lock)
 384 {
 385         return raw_spin_trylock_bh(&lock->rlock);
 386 }
 387
 388 static inline int spin_trylock_irq(spinlock_t *lock)
 389 {
 390         return raw_spin_trylock_irq(&lock->rlock);
 391 }
 392
 393 #define spin_trylock_irqsave(lock, flags)                       \
 394 ({                                                              \
 395         raw_spin_trylock_irqsave(spinlock_check(lock), flags); \
 396 })
 397
 398 static inline void spin_unlock_wait(spinlock_t *lock)
 399 {
 400         raw_spin_unlock_wait(&lock->rlock);
 401 }
 402
 403 static inline int spin_is_locked(spinlock_t *lock)
 404 {
 405         return raw_spin_is_locked(&lock->rlock);
 406 }
 407
 408 static inline int spin_is_contended(spinlock_t *lock)
 409 {
 410         return raw_spin_is_contended(&lock->rlock);
 411 }
 412
 413 static inline int spin_can_lock(spinlock_t *lock)
 414 {
 415         return raw_spin_can_lock(&lock->rlock);
 416 }
 417
 418 #define assert_spin_locked(lock)        assert_raw_spin_locked(&(lock)->rlock)
 419
 420 /*
 421  * Pull the atomic_t declaration:
 422  * (asm-mips/atomic.h needs above definitions)
 423  */
 424 #include <linux/atomic.h>
 425 /**
 426  * atomic_dec_and_lock - lock on reaching reference count zero
 427  * @atomic: the atomic counter
 428  * @lock: the spinlock in question
 429  *
 430  * Decrements @atomic by 1.  If the result is 0, returns true and locks
 431  * @lock.  Returns false for all other cases.
 432  */
 433 extern int _atomic_dec_and_lock(atomic_t *atomic, spinlock_t *lock);
 434 #define atomic_dec_and_lock(atomic, lock) \
 435                 __cond_lock(lock, _atomic_dec_and_lock(atomic, lock))
 436
 437 #endif /* !PREEMPT_RT_FULL */
 438
 439 #endif /* __LINUX_SPINLOCK_H */