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 raw_spinlock_t/raw_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 __raw_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 __raw_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/thread_info.h>
  54#include <linux/kernel.h>
  55#include <linux/stringify.h>
  56#include <linux/bottom_half.h>
  57
  58#include <asm/system.h>
  59
  60/*
  61 * Must define these before including other files, inline functions need them
  62 */
  63#define LOCK_SECTION_NAME ".text.lock."KBUILD_BASENAME
  64
  65#define LOCK_SECTION_START(extra)               \
  66        ".subsection 1\n\t"                     \
  67        extra                                   \
  68        ".ifndef " LOCK_SECTION_NAME "\n\t"     \
  69        LOCK_SECTION_NAME ":\n\t"               \
  70        ".endif\n"
  71
  72#define LOCK_SECTION_END                        \
  73        ".previous\n\t"
  74
  75#define __lockfunc __attribute__((section(".spinlock.text")))
  76
  77/*
  78 * Pull the raw_spinlock_t and raw_rwlock_t definitions:
  79 */
  80#include <linux/spinlock_types.h>
  81
  82extern int __lockfunc generic__raw_read_trylock(raw_rwlock_t *lock);
  83
  84/*
  85 * Pull the __raw*() functions/declarations (UP-nondebug doesnt need them):
  86 */
  87#ifdef CONFIG_SMP
  88# include <asm/spinlock.h>
  89#else
  90# include <linux/spinlock_up.h>
  91#endif
  92
  93#ifdef CONFIG_DEBUG_SPINLOCK
  94  extern void __spin_lock_init(spinlock_t *lock, const char *name,
  95                               struct lock_class_key *key);
  96# define spin_lock_init(lock)                                   \
  97do {                                                            \
  98        static struct lock_class_key __key;                     \
  99                                                                \
 100        __spin_lock_init((lock), #lock, &__key);                \
 101} while (0)
 102
 103#else
 104# define spin_lock_init(lock)                                   \
 105        do { *(lock) = SPIN_LOCK_UNLOCKED; } while (0)
 106#endif
 107
 108#ifdef CONFIG_DEBUG_SPINLOCK
 109  extern void __rwlock_init(rwlock_t *lock, const char *name,
 110                            struct lock_class_key *key);
 111# define rwlock_init(lock)                                      \
 112do {                                                            \
 113        static struct lock_class_key __key;                     \
 114                                                                \
 115        __rwlock_init((lock), #lock, &__key);                   \
 116} while (0)
 117#else
 118# define rwlock_init(lock)                                      \
 119        do { *(lock) = RW_LOCK_UNLOCKED; } while (0)
 120#endif
 121
 122#define spin_is_locked(lock)    __raw_spin_is_locked(&(lock)->raw_lock)
 123
 124#ifdef CONFIG_GENERIC_LOCKBREAK
 125#define spin_is_contended(lock) ((lock)->break_lock)
 126#else
 127
 128#ifdef __raw_spin_is_contended
 129#define spin_is_contended(lock) __raw_spin_is_contended(&(lock)->raw_lock)
 130#else
 131#define spin_is_contended(lock) (((void)(lock), 0))
 132#endif /*__raw_spin_is_contended*/
 133#endif
 134
 135/* The lock does not imply full memory barrier. */
 136#ifndef ARCH_HAS_SMP_MB_AFTER_LOCK
 137static inline void smp_mb__after_lock(void) { smp_mb(); }
 138#endif
 139
 140/**
 141 * spin_unlock_wait - wait until the spinlock gets unlocked
 142 * @lock: the spinlock in question.
 143 */
 144#define spin_unlock_wait(lock)  __raw_spin_unlock_wait(&(lock)->raw_lock)
 145
 146#ifdef CONFIG_DEBUG_SPINLOCK
 147 extern void _raw_spin_lock(spinlock_t *lock);
 148#define _raw_spin_lock_flags(lock, flags) _raw_spin_lock(lock)
 149 extern int _raw_spin_trylock(spinlock_t *lock);
 150 extern void _raw_spin_unlock(spinlock_t *lock);
 151 extern void _raw_read_lock(rwlock_t *lock);
 152#define _raw_read_lock_flags(lock, flags) _raw_read_lock(lock)
 153 extern int _raw_read_trylock(rwlock_t *lock);
 154 extern void _raw_read_unlock(rwlock_t *lock);
 155 extern void _raw_write_lock(rwlock_t *lock);
 156#define _raw_write_lock_flags(lock, flags) _raw_write_lock(lock)
 157 extern int _raw_write_trylock(rwlock_t *lock);
 158 extern void _raw_write_unlock(rwlock_t *lock);
 159#else
 160# define _raw_spin_lock(lock)           __raw_spin_lock(&(lock)->raw_lock)
 161# define _raw_spin_lock_flags(lock, flags) \
 162                __raw_spin_lock_flags(&(lock)->raw_lock, *(flags))
 163# define _raw_spin_trylock(lock)        __raw_spin_trylock(&(lock)->raw_lock)
 164# define _raw_spin_unlock(lock)         __raw_spin_unlock(&(lock)->raw_lock)
 165# define _raw_read_lock(rwlock)         __raw_read_lock(&(rwlock)->raw_lock)
 166# define _raw_read_lock_flags(lock, flags) \
 167                __raw_read_lock_flags(&(lock)->raw_lock, *(flags))
 168# define _raw_read_trylock(rwlock)      __raw_read_trylock(&(rwlock)->raw_lock)
 169# define _raw_read_unlock(rwlock)       __raw_read_unlock(&(rwlock)->raw_lock)
 170# define _raw_write_lock(rwlock)        __raw_write_lock(&(rwlock)->raw_lock)
 171# define _raw_write_lock_flags(lock, flags) \
 172                __raw_write_lock_flags(&(lock)->raw_lock, *(flags))
 173# define _raw_write_trylock(rwlock)     __raw_write_trylock(&(rwlock)->raw_lock)
 174# define _raw_write_unlock(rwlock)      __raw_write_unlock(&(rwlock)->raw_lock)
 175#endif
 176
 177#define read_can_lock(rwlock)           __raw_read_can_lock(&(rwlock)->raw_lock)
 178#define write_can_lock(rwlock)          __raw_write_can_lock(&(rwlock)->raw_lock)
 179
 180/*
 181 * Define the various spin_lock and rw_lock methods.  Note we define these
 182 * regardless of whether CONFIG_SMP or CONFIG_PREEMPT are set. The various
 183 * methods are defined as nops in the case they are not required.
 184 */
 185#define spin_trylock(lock)              __cond_lock(lock, _spin_trylock(lock))
 186#define read_trylock(lock)              __cond_lock(lock, _read_trylock(lock))
 187#define write_trylock(lock)             __cond_lock(lock, _write_trylock(lock))
 188
 189#define spin_lock(lock)                 _spin_lock(lock)
 190
 191#ifdef CONFIG_DEBUG_LOCK_ALLOC
 192# define spin_lock_nested(lock, subclass) _spin_lock_nested(lock, subclass)
 193# define spin_lock_nest_lock(lock, nest_lock)                           \
 194         do {                                                           \
 195                 typecheck(struct lockdep_map *, &(nest_lock)->dep_map);\
 196                 _spin_lock_nest_lock(lock, &(nest_lock)->dep_map);     \
 197         } while (0)
 198#else
 199# define spin_lock_nested(lock, subclass) _spin_lock(lock)
 200# define spin_lock_nest_lock(lock, nest_lock) _spin_lock(lock)
 201#endif
 202
 203#define write_lock(lock)                _write_lock(lock)
 204#define read_lock(lock)                 _read_lock(lock)
 205
 206#if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
 207
 208#define spin_lock_irqsave(lock, flags)                  \
 209        do {                                            \
 210                typecheck(unsigned long, flags);        \
 211                flags = _spin_lock_irqsave(lock);       \
 212        } while (0)
 213#define read_lock_irqsave(lock, flags)                  \
 214        do {                                            \
 215                typecheck(unsigned long, flags);        \
 216                flags = _read_lock_irqsave(lock);       \
 217        } while (0)
 218#define write_lock_irqsave(lock, flags)                 \
 219        do {                                            \
 220                typecheck(unsigned long, flags);        \
 221                flags = _write_lock_irqsave(lock);      \
 222        } while (0)
 223
 224#ifdef CONFIG_DEBUG_LOCK_ALLOC
 225#define spin_lock_irqsave_nested(lock, flags, subclass)                 \
 226        do {                                                            \
 227                typecheck(unsigned long, flags);                        \
 228                flags = _spin_lock_irqsave_nested(lock, subclass);      \
 229        } while (0)
 230#else
 231#define spin_lock_irqsave_nested(lock, flags, subclass)                 \
 232        do {                                                            \
 233                typecheck(unsigned long, flags);                        \
 234                flags = _spin_lock_irqsave(lock);                       \
 235        } while (0)
 236#endif
 237
 238#else
 239
 240#define spin_lock_irqsave(lock, flags)                  \
 241        do {                                            \
 242                typecheck(unsigned long, flags);        \
 243                _spin_lock_irqsave(lock, flags);        \
 244        } while (0)
 245#define read_lock_irqsave(lock, flags)                  \
 246        do {                                            \
 247                typecheck(unsigned long, flags);        \
 248                _read_lock_irqsave(lock, flags);        \
 249        } while (0)
 250#define write_lock_irqsave(lock, flags)                 \
 251        do {                                            \
 252                typecheck(unsigned long, flags);        \
 253                _write_lock_irqsave(lock, flags);       \
 254        } while (0)
 255#define spin_lock_irqsave_nested(lock, flags, subclass) \
 256        spin_lock_irqsave(lock, flags)
 257
 258#endif
 259
 260#define spin_lock_irq(lock)             _spin_lock_irq(lock)
 261#define spin_lock_bh(lock)              _spin_lock_bh(lock)
 262#define read_lock_irq(lock)             _read_lock_irq(lock)
 263#define read_lock_bh(lock)              _read_lock_bh(lock)
 264#define write_lock_irq(lock)            _write_lock_irq(lock)
 265#define write_lock_bh(lock)             _write_lock_bh(lock)
 266#define spin_unlock(lock)               _spin_unlock(lock)
 267#define read_unlock(lock)               _read_unlock(lock)
 268#define write_unlock(lock)              _write_unlock(lock)
 269#define spin_unlock_irq(lock)           _spin_unlock_irq(lock)
 270#define read_unlock_irq(lock)           _read_unlock_irq(lock)
 271#define write_unlock_irq(lock)          _write_unlock_irq(lock)
 272
 273#define spin_unlock_irqrestore(lock, flags)             \
 274        do {                                            \
 275                typecheck(unsigned long, flags);        \
 276                _spin_unlock_irqrestore(lock, flags);   \
 277        } while (0)
 278#define spin_unlock_bh(lock)            _spin_unlock_bh(lock)
 279
 280#define read_unlock_irqrestore(lock, flags)             \
 281        do {                                            \
 282                typecheck(unsigned long, flags);        \
 283                _read_unlock_irqrestore(lock, flags);   \
 284        } while (0)
 285#define read_unlock_bh(lock)            _read_unlock_bh(lock)
 286
 287#define write_unlock_irqrestore(lock, flags)            \
 288        do {                                            \
 289                typecheck(unsigned long, flags);        \
 290                _write_unlock_irqrestore(lock, flags);  \
 291        } while (0)
 292#define write_unlock_bh(lock)           _write_unlock_bh(lock)
 293
 294#define spin_trylock_bh(lock)   __cond_lock(lock, _spin_trylock_bh(lock))
 295
 296#define spin_trylock_irq(lock) \
 297({ \
 298        local_irq_disable(); \
 299        spin_trylock(lock) ? \
 300        1 : ({ local_irq_enable(); 0;  }); \
 301})
 302
 303#define spin_trylock_irqsave(lock, flags) \
 304({ \
 305        local_irq_save(flags); \
 306        spin_trylock(lock) ? \
 307        1 : ({ local_irq_restore(flags); 0; }); \
 308})
 309
 310#define write_trylock_irqsave(lock, flags) \
 311({ \
 312        local_irq_save(flags); \
 313        write_trylock(lock) ? \
 314        1 : ({ local_irq_restore(flags); 0; }); \
 315})
 316
 317/*
 318 * Pull the atomic_t declaration:
 319 * (asm-mips/atomic.h needs above definitions)
 320 */
 321#include <asm/atomic.h>
 322/**
 323 * atomic_dec_and_lock - lock on reaching reference count zero
 324 * @atomic: the atomic counter
 325 * @lock: the spinlock in question
 326 *
 327 * Decrements @atomic by 1.  If the result is 0, returns true and locks
 328 * @lock.  Returns false for all other cases.
 329 */
 330extern int _atomic_dec_and_lock(atomic_t *atomic, spinlock_t *lock);
 331#define atomic_dec_and_lock(atomic, lock) \
 332                __cond_lock(lock, _atomic_dec_and_lock(atomic, lock))
 333
 334/**
 335 * spin_can_lock - would spin_trylock() succeed?
 336 * @lock: the spinlock in question.
 337 */
 338#define spin_can_lock(lock)     (!spin_is_locked(lock))
 339
 340/*
 341 * Pull the _spin_*()/_read_*()/_write_*() functions/declarations:
 342 */
 343#if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
 344# include <linux/spinlock_api_smp.h>
 345#else
 346# include <linux/spinlock_api_up.h>
 347#endif
 348
 349#endif /* __LINUX_SPINLOCK_H */
 350