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 LOADs and STOREs 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 * raw_spin_unlock_wait - wait until the spinlock gets unlocked
 135 * @lock: the spinlock in question.
 136 */
 137#define raw_spin_unlock_wait(lock)      arch_spin_unlock_wait(&(lock)->raw_lock)
 138
 139#ifdef CONFIG_DEBUG_SPINLOCK
 140 extern void do_raw_spin_lock(raw_spinlock_t *lock) __acquires(lock);
 141#define do_raw_spin_lock_flags(lock, flags) do_raw_spin_lock(lock)
 142 extern int do_raw_spin_trylock(raw_spinlock_t *lock);
 143 extern void do_raw_spin_unlock(raw_spinlock_t *lock) __releases(lock);
 144#else
 145static inline void do_raw_spin_lock(raw_spinlock_t *lock) __acquires(lock)
 146{
 147        __acquire(lock);
 148        arch_spin_lock(&lock->raw_lock);
 149}
 150
 151static inline void
 152do_raw_spin_lock_flags(raw_spinlock_t *lock, unsigned long *flags) __acquires(lock)
 153{
 154        __acquire(lock);
 155        arch_spin_lock_flags(&lock->raw_lock, *flags);
 156}
 157
 158static inline int do_raw_spin_trylock(raw_spinlock_t *lock)
 159{
 160        return arch_spin_trylock(&(lock)->raw_lock);
 161}
 162
 163static inline void do_raw_spin_unlock(raw_spinlock_t *lock) __releases(lock)
 164{
 165        arch_spin_unlock(&lock->raw_lock);
 166        __release(lock);
 167}
 168#endif
 169
 170/*
 171 * Define the various spin_lock methods.  Note we define these
 172 * regardless of whether CONFIG_SMP or CONFIG_PREEMPT are set. The
 173 * various methods are defined as nops in the case they are not
 174 * required.
 175 */
 176#define raw_spin_trylock(lock)  __cond_lock(lock, _raw_spin_trylock(lock))
 177
 178#define raw_spin_lock(lock)     _raw_spin_lock(lock)
 179
 180#ifdef CONFIG_DEBUG_LOCK_ALLOC
 181# define raw_spin_lock_nested(lock, subclass) \
 182        _raw_spin_lock_nested(lock, subclass)
 183# define raw_spin_lock_bh_nested(lock, subclass) \
 184        _raw_spin_lock_bh_nested(lock, subclass)
 185
 186# define raw_spin_lock_nest_lock(lock, nest_lock)                       \
 187         do {                                                           \
 188                 typecheck(struct lockdep_map *, &(nest_lock)->dep_map);\
 189                 _raw_spin_lock_nest_lock(lock, &(nest_lock)->dep_map); \
 190         } while (0)
 191#else
 192/*
 193 * Always evaluate the 'subclass' argument to avoid that the compiler
 194 * warns about set-but-not-used variables when building with
 195 * CONFIG_DEBUG_LOCK_ALLOC=n and with W=1.
 196 */
 197# define raw_spin_lock_nested(lock, subclass)           \
 198        _raw_spin_lock(((void)(subclass), (lock)))
 199# define raw_spin_lock_nest_lock(lock, nest_lock)       _raw_spin_lock(lock)
 200# define raw_spin_lock_bh_nested(lock, subclass)        _raw_spin_lock_bh(lock)
 201#endif
 202
 203#if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
 204
 205#define raw_spin_lock_irqsave(lock, flags)                      \
 206        do {                                            \
 207                typecheck(unsigned long, flags);        \
 208                flags = _raw_spin_lock_irqsave(lock);   \
 209        } while (0)
 210
 211#ifdef CONFIG_DEBUG_LOCK_ALLOC
 212#define raw_spin_lock_irqsave_nested(lock, flags, subclass)             \
 213        do {                                                            \
 214                typecheck(unsigned long, flags);                        \
 215                flags = _raw_spin_lock_irqsave_nested(lock, subclass);  \
 216        } while (0)
 217#else
 218#define raw_spin_lock_irqsave_nested(lock, flags, subclass)             \
 219        do {                                                            \
 220                typecheck(unsigned long, flags);                        \
 221                flags = _raw_spin_lock_irqsave(lock);                   \
 222        } while (0)
 223#endif
 224
 225#else
 226
 227#define raw_spin_lock_irqsave(lock, flags)              \
 228        do {                                            \
 229                typecheck(unsigned long, flags);        \
 230                _raw_spin_lock_irqsave(lock, flags);    \
 231        } while (0)
 232
 233#define raw_spin_lock_irqsave_nested(lock, flags, subclass)     \
 234        raw_spin_lock_irqsave(lock, flags)
 235
 236#endif
 237
 238#define raw_spin_lock_irq(lock)         _raw_spin_lock_irq(lock)
 239#define raw_spin_lock_bh(lock)          _raw_spin_lock_bh(lock)
 240#define raw_spin_unlock(lock)           _raw_spin_unlock(lock)
 241#define raw_spin_unlock_irq(lock)       _raw_spin_unlock_irq(lock)
 242
 243#define raw_spin_unlock_irqrestore(lock, flags)         \
 244        do {                                                    \
 245                typecheck(unsigned long, flags);                \
 246                _raw_spin_unlock_irqrestore(lock, flags);       \
 247        } while (0)
 248#define raw_spin_unlock_bh(lock)        _raw_spin_unlock_bh(lock)
 249
 250#define raw_spin_trylock_bh(lock) \
 251        __cond_lock(lock, _raw_spin_trylock_bh(lock))
 252
 253#define raw_spin_trylock_irq(lock) \
 254({ \
 255        local_irq_disable(); \
 256        raw_spin_trylock(lock) ? \
 257        1 : ({ local_irq_enable(); 0;  }); \
 258})
 259
 260#define raw_spin_trylock_irqsave(lock, flags) \
 261({ \
 262        local_irq_save(flags); \
 263        raw_spin_trylock(lock) ? \
 264        1 : ({ local_irq_restore(flags); 0; }); \
 265})
 266
 267/**
 268 * raw_spin_can_lock - would raw_spin_trylock() succeed?
 269 * @lock: the spinlock in question.
 270 */
 271#define raw_spin_can_lock(lock) (!raw_spin_is_locked(lock))
 272
 273/* Include rwlock functions */
 274#include <linux/rwlock.h>
 275
 276/*
 277 * Pull the _spin_*()/_read_*()/_write_*() functions/declarations:
 278 */
 279#if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
 280# include <linux/spinlock_api_smp.h>
 281#else
 282# include <linux/spinlock_api_up.h>
 283#endif
 284
 285/*
 286 * Map the spin_lock functions to the raw variants for PREEMPT_RT=n
 287 */
 288
 289static __always_inline raw_spinlock_t *spinlock_check(spinlock_t *lock)
 290{
 291        return &lock->rlock;
 292}
 293
 294#define spin_lock_init(_lock)                           \
 295do {                                                    \
 296        spinlock_check(_lock);                          \
 297        raw_spin_lock_init(&(_lock)->rlock);            \
 298} while (0)
 299
 300static __always_inline void spin_lock(spinlock_t *lock)
 301{
 302        raw_spin_lock(&lock->rlock);
 303}
 304
 305static __always_inline void spin_lock_bh(spinlock_t *lock)
 306{
 307        raw_spin_lock_bh(&lock->rlock);
 308}
 309
 310static __always_inline int spin_trylock(spinlock_t *lock)
 311{
 312        return raw_spin_trylock(&lock->rlock);
 313}
 314
 315#define spin_lock_nested(lock, subclass)                        \
 316do {                                                            \
 317        raw_spin_lock_nested(spinlock_check(lock), subclass);   \
 318} while (0)
 319
 320#define spin_lock_bh_nested(lock, subclass)                     \
 321do {                                                            \
 322        raw_spin_lock_bh_nested(spinlock_check(lock), subclass);\
 323} while (0)
 324
 325#define spin_lock_nest_lock(lock, nest_lock)                            \
 326do {                                                                    \
 327        raw_spin_lock_nest_lock(spinlock_check(lock), nest_lock);       \
 328} while (0)
 329
 330static __always_inline void spin_lock_irq(spinlock_t *lock)
 331{
 332        raw_spin_lock_irq(&lock->rlock);
 333}
 334
 335#define spin_lock_irqsave(lock, flags)                          \
 336do {                                                            \
 337        raw_spin_lock_irqsave(spinlock_check(lock), flags);     \
 338} while (0)
 339
 340#define spin_lock_irqsave_nested(lock, flags, subclass)                 \
 341do {                                                                    \
 342        raw_spin_lock_irqsave_nested(spinlock_check(lock), flags, subclass); \
 343} while (0)
 344
 345static __always_inline void spin_unlock(spinlock_t *lock)
 346{
 347        raw_spin_unlock(&lock->rlock);
 348}
 349
 350static __always_inline void spin_unlock_bh(spinlock_t *lock)
 351{
 352        raw_spin_unlock_bh(&lock->rlock);
 353}
 354
 355static __always_inline void spin_unlock_irq(spinlock_t *lock)
 356{
 357        raw_spin_unlock_irq(&lock->rlock);
 358}
 359
 360static __always_inline void spin_unlock_irqrestore(spinlock_t *lock, unsigned long flags)
 361{
 362        raw_spin_unlock_irqrestore(&lock->rlock, flags);
 363}
 364
 365static __always_inline int spin_trylock_bh(spinlock_t *lock)
 366{
 367        return raw_spin_trylock_bh(&lock->rlock);
 368}
 369
 370static __always_inline int spin_trylock_irq(spinlock_t *lock)
 371{
 372        return raw_spin_trylock_irq(&lock->rlock);
 373}
 374
 375#define spin_trylock_irqsave(lock, flags)                       \
 376({                                                              \
 377        raw_spin_trylock_irqsave(spinlock_check(lock), flags); \
 378})
 379
 380static __always_inline void spin_unlock_wait(spinlock_t *lock)
 381{
 382        raw_spin_unlock_wait(&lock->rlock);
 383}
 384
 385static __always_inline int spin_is_locked(spinlock_t *lock)
 386{
 387        return raw_spin_is_locked(&lock->rlock);
 388}
 389
 390static __always_inline int spin_is_contended(spinlock_t *lock)
 391{
 392        return raw_spin_is_contended(&lock->rlock);
 393}
 394
 395static __always_inline int spin_can_lock(spinlock_t *lock)
 396{
 397        return raw_spin_can_lock(&lock->rlock);
 398}
 399
 400#define assert_spin_locked(lock)        assert_raw_spin_locked(&(lock)->rlock)
 401
 402/*
 403 * Pull the atomic_t declaration:
 404 * (asm-mips/atomic.h needs above definitions)
 405 */
 406#include <linux/atomic.h>
 407/**
 408 * atomic_dec_and_lock - lock on reaching reference count zero
 409 * @atomic: the atomic counter
 410 * @lock: the spinlock in question
 411 *
 412 * Decrements @atomic by 1.  If the result is 0, returns true and locks
 413 * @lock.  Returns false for all other cases.
 414 */
 415extern int _atomic_dec_and_lock(atomic_t *atomic, spinlock_t *lock);
 416#define atomic_dec_and_lock(atomic, lock) \
 417                __cond_lock(lock, _atomic_dec_and_lock(atomic, lock))
 418
 419#endif /* __LINUX_SPINLOCK_H */
 420