linux/include/linux/spinlock.h
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   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)                               \
  96do {                                                            \
  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
 155static 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
 161static inline void
 162do_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
 168static inline int do_raw_spin_trylock(raw_spinlock_t *lock)
 169{
 170        return arch_spin_trylock(&(lock)->raw_lock);
 171}
 172
 173static 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#include <linux/rwlock.h>
 285
 286/*
 287 * Pull the _spin_*()/_read_*()/_write_*() functions/declarations:
 288 */
 289#if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
 290# include <linux/spinlock_api_smp.h>
 291#else
 292# include <linux/spinlock_api_up.h>
 293#endif
 294
 295/*
 296 * Map the spin_lock functions to the raw variants for PREEMPT_RT=n
 297 */
 298
 299static inline raw_spinlock_t *spinlock_check(spinlock_t *lock)
 300{
 301        return &lock->rlock;
 302}
 303
 304#define spin_lock_init(_lock)                           \
 305do {                                                    \
 306        spinlock_check(_lock);                          \
 307        raw_spin_lock_init(&(_lock)->rlock);            \
 308} while (0)
 309
 310static inline void spin_lock(spinlock_t *lock)
 311{
 312        raw_spin_lock(&lock->rlock);
 313}
 314
 315static inline void spin_lock_bh(spinlock_t *lock)
 316{
 317        raw_spin_lock_bh(&lock->rlock);
 318}
 319
 320static inline int spin_trylock(spinlock_t *lock)
 321{
 322        return raw_spin_trylock(&lock->rlock);
 323}
 324
 325#define spin_lock_nested(lock, subclass)                        \
 326do {                                                            \
 327        raw_spin_lock_nested(spinlock_check(lock), subclass);   \
 328} while (0)
 329
 330#define spin_lock_bh_nested(lock, subclass)                     \
 331do {                                                            \
 332        raw_spin_lock_bh_nested(spinlock_check(lock), subclass);\
 333} while (0)
 334
 335#define spin_lock_nest_lock(lock, nest_lock)                            \
 336do {                                                                    \
 337        raw_spin_lock_nest_lock(spinlock_check(lock), nest_lock);       \
 338} while (0)
 339
 340static inline void spin_lock_irq(spinlock_t *lock)
 341{
 342        raw_spin_lock_irq(&lock->rlock);
 343}
 344
 345#define spin_lock_irqsave(lock, flags)                          \
 346do {                                                            \
 347        raw_spin_lock_irqsave(spinlock_check(lock), flags);     \
 348} while (0)
 349
 350#define spin_lock_irqsave_nested(lock, flags, subclass)                 \
 351do {                                                                    \
 352        raw_spin_lock_irqsave_nested(spinlock_check(lock), flags, subclass); \
 353} while (0)
 354
 355static inline void spin_unlock(spinlock_t *lock)
 356{
 357        raw_spin_unlock(&lock->rlock);
 358}
 359
 360static inline void spin_unlock_bh(spinlock_t *lock)
 361{
 362        raw_spin_unlock_bh(&lock->rlock);
 363}
 364
 365static inline void spin_unlock_irq(spinlock_t *lock)
 366{
 367        raw_spin_unlock_irq(&lock->rlock);
 368}
 369
 370static inline void spin_unlock_irqrestore(spinlock_t *lock, unsigned long flags)
 371{
 372        raw_spin_unlock_irqrestore(&lock->rlock, flags);
 373}
 374
 375static inline int spin_trylock_bh(spinlock_t *lock)
 376{
 377        return raw_spin_trylock_bh(&lock->rlock);
 378}
 379
 380static inline int spin_trylock_irq(spinlock_t *lock)
 381{
 382        return raw_spin_trylock_irq(&lock->rlock);
 383}
 384
 385#define spin_trylock_irqsave(lock, flags)                       \
 386({                                                              \
 387        raw_spin_trylock_irqsave(spinlock_check(lock), flags); \
 388})
 389
 390static inline void spin_unlock_wait(spinlock_t *lock)
 391{
 392        raw_spin_unlock_wait(&lock->rlock);
 393}
 394
 395static inline int spin_is_locked(spinlock_t *lock)
 396{
 397        return raw_spin_is_locked(&lock->rlock);
 398}
 399
 400static inline int spin_is_contended(spinlock_t *lock)
 401{
 402        return raw_spin_is_contended(&lock->rlock);
 403}
 404
 405static inline int spin_can_lock(spinlock_t *lock)
 406{
 407        return raw_spin_can_lock(&lock->rlock);
 408}
 409
 410#define assert_spin_locked(lock)        assert_raw_spin_locked(&(lock)->rlock)
 411
 412/*
 413 * Pull the atomic_t declaration:
 414 * (asm-mips/atomic.h needs above definitions)
 415 */
 416#include <linux/atomic.h>
 417/**
 418 * atomic_dec_and_lock - lock on reaching reference count zero
 419 * @atomic: the atomic counter
 420 * @lock: the spinlock in question
 421 *
 422 * Decrements @atomic by 1.  If the result is 0, returns true and locks
 423 * @lock.  Returns false for all other cases.
 424 */
 425extern int _atomic_dec_and_lock(atomic_t *atomic, spinlock_t *lock);
 426#define atomic_dec_and_lock(atomic, lock) \
 427                __cond_lock(lock, _atomic_dec_and_lock(atomic, lock))
 428
 429#endif /* __LINUX_SPINLOCK_H */
 430