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 * 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
 184# define raw_spin_lock_nest_lock(lock, nest_lock)                       \
 185         do {                                                           \
 186                 typecheck(struct lockdep_map *, &(nest_lock)->dep_map);\
 187                 _raw_spin_lock_nest_lock(lock, &(nest_lock)->dep_map); \
 188         } while (0)
 189#else
 190# define raw_spin_lock_nested(lock, subclass)           _raw_spin_lock(lock)
 191# define raw_spin_lock_nest_lock(lock, nest_lock)       _raw_spin_lock(lock)
 192#endif
 193
 194#if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
 195
 196#define raw_spin_lock_irqsave(lock, flags)                      \
 197        do {                                            \
 198                typecheck(unsigned long, flags);        \
 199                flags = _raw_spin_lock_irqsave(lock);   \
 200        } while (0)
 201
 202#ifdef CONFIG_DEBUG_LOCK_ALLOC
 203#define raw_spin_lock_irqsave_nested(lock, flags, subclass)             \
 204        do {                                                            \
 205                typecheck(unsigned long, flags);                        \
 206                flags = _raw_spin_lock_irqsave_nested(lock, subclass);  \
 207        } while (0)
 208#else
 209#define raw_spin_lock_irqsave_nested(lock, flags, subclass)             \
 210        do {                                                            \
 211                typecheck(unsigned long, flags);                        \
 212                flags = _raw_spin_lock_irqsave(lock);                   \
 213        } while (0)
 214#endif
 215
 216#else
 217
 218#define raw_spin_lock_irqsave(lock, flags)              \
 219        do {                                            \
 220                typecheck(unsigned long, flags);        \
 221                _raw_spin_lock_irqsave(lock, flags);    \
 222        } while (0)
 223
 224#define raw_spin_lock_irqsave_nested(lock, flags, subclass)     \
 225        raw_spin_lock_irqsave(lock, flags)
 226
 227#endif
 228
 229#define raw_spin_lock_irq(lock)         _raw_spin_lock_irq(lock)
 230#define raw_spin_lock_bh(lock)          _raw_spin_lock_bh(lock)
 231#define raw_spin_unlock(lock)           _raw_spin_unlock(lock)
 232#define raw_spin_unlock_irq(lock)       _raw_spin_unlock_irq(lock)
 233
 234#define raw_spin_unlock_irqrestore(lock, flags)         \
 235        do {                                                    \
 236                typecheck(unsigned long, flags);                \
 237                _raw_spin_unlock_irqrestore(lock, flags);       \
 238        } while (0)
 239#define raw_spin_unlock_bh(lock)        _raw_spin_unlock_bh(lock)
 240
 241#define raw_spin_trylock_bh(lock) \
 242        __cond_lock(lock, _raw_spin_trylock_bh(lock))
 243
 244#define raw_spin_trylock_irq(lock) \
 245({ \
 246        local_irq_disable(); \
 247        raw_spin_trylock(lock) ? \
 248        1 : ({ local_irq_enable(); 0;  }); \
 249})
 250
 251#define raw_spin_trylock_irqsave(lock, flags) \
 252({ \
 253        local_irq_save(flags); \
 254        raw_spin_trylock(lock) ? \
 255        1 : ({ local_irq_restore(flags); 0; }); \
 256})
 257
 258/**
 259 * raw_spin_can_lock - would raw_spin_trylock() succeed?
 260 * @lock: the spinlock in question.
 261 */
 262#define raw_spin_can_lock(lock) (!raw_spin_is_locked(lock))
 263
 264/* Include rwlock functions */
 265#include <linux/rwlock.h>
 266
 267/*
 268 * Pull the _spin_*()/_read_*()/_write_*() functions/declarations:
 269 */
 270#if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
 271# include <linux/spinlock_api_smp.h>
 272#else
 273# include <linux/spinlock_api_up.h>
 274#endif
 275
 276/*
 277 * Map the spin_lock functions to the raw variants for PREEMPT_RT=n
 278 */
 279
 280static inline raw_spinlock_t *spinlock_check(spinlock_t *lock)
 281{
 282        return &lock->rlock;
 283}
 284
 285#define spin_lock_init(_lock)                           \
 286do {                                                    \
 287        spinlock_check(_lock);                          \
 288        raw_spin_lock_init(&(_lock)->rlock);            \
 289} while (0)
 290
 291static inline void spin_lock(spinlock_t *lock)
 292{
 293        raw_spin_lock(&lock->rlock);
 294}
 295
 296static inline void spin_lock_bh(spinlock_t *lock)
 297{
 298        raw_spin_lock_bh(&lock->rlock);
 299}
 300
 301static inline int spin_trylock(spinlock_t *lock)
 302{
 303        return raw_spin_trylock(&lock->rlock);
 304}
 305
 306#define spin_lock_nested(lock, subclass)                        \
 307do {                                                            \
 308        raw_spin_lock_nested(spinlock_check(lock), subclass);   \
 309} while (0)
 310
 311#define spin_lock_nest_lock(lock, nest_lock)                            \
 312do {                                                                    \
 313        raw_spin_lock_nest_lock(spinlock_check(lock), nest_lock);       \
 314} while (0)
 315
 316static inline void spin_lock_irq(spinlock_t *lock)
 317{
 318        raw_spin_lock_irq(&lock->rlock);
 319}
 320
 321#define spin_lock_irqsave(lock, flags)                          \
 322do {                                                            \
 323        raw_spin_lock_irqsave(spinlock_check(lock), flags);     \
 324} while (0)
 325
 326#define spin_lock_irqsave_nested(lock, flags, subclass)                 \
 327do {                                                                    \
 328        raw_spin_lock_irqsave_nested(spinlock_check(lock), flags, subclass); \
 329} while (0)
 330
 331static inline void spin_unlock(spinlock_t *lock)
 332{
 333        raw_spin_unlock(&lock->rlock);
 334}
 335
 336static inline void spin_unlock_bh(spinlock_t *lock)
 337{
 338        raw_spin_unlock_bh(&lock->rlock);
 339}
 340
 341static inline void spin_unlock_irq(spinlock_t *lock)
 342{
 343        raw_spin_unlock_irq(&lock->rlock);
 344}
 345
 346static inline void spin_unlock_irqrestore(spinlock_t *lock, unsigned long flags)
 347{
 348        raw_spin_unlock_irqrestore(&lock->rlock, flags);
 349}
 350
 351static inline int spin_trylock_bh(spinlock_t *lock)
 352{
 353        return raw_spin_trylock_bh(&lock->rlock);
 354}
 355
 356static inline int spin_trylock_irq(spinlock_t *lock)
 357{
 358        return raw_spin_trylock_irq(&lock->rlock);
 359}
 360
 361#define spin_trylock_irqsave(lock, flags)                       \
 362({                                                              \
 363        raw_spin_trylock_irqsave(spinlock_check(lock), flags); \
 364})
 365
 366static inline void spin_unlock_wait(spinlock_t *lock)
 367{
 368        raw_spin_unlock_wait(&lock->rlock);
 369}
 370
 371static inline int spin_is_locked(spinlock_t *lock)
 372{
 373        return raw_spin_is_locked(&lock->rlock);
 374}
 375
 376static inline int spin_is_contended(spinlock_t *lock)
 377{
 378        return raw_spin_is_contended(&lock->rlock);
 379}
 380
 381static inline int spin_can_lock(spinlock_t *lock)
 382{
 383        return raw_spin_can_lock(&lock->rlock);
 384}
 385
 386#define assert_spin_locked(lock)        assert_raw_spin_locked(&(lock)->rlock)
 387
 388/*
 389 * Pull the atomic_t declaration:
 390 * (asm-mips/atomic.h needs above definitions)
 391 */
 392#include <linux/atomic.h>
 393/**
 394 * atomic_dec_and_lock - lock on reaching reference count zero
 395 * @atomic: the atomic counter
 396 * @lock: the spinlock in question
 397 *
 398 * Decrements @atomic by 1.  If the result is 0, returns true and locks
 399 * @lock.  Returns false for all other cases.
 400 */
 401extern int _atomic_dec_and_lock(atomic_t *atomic, spinlock_t *lock);
 402#define atomic_dec_and_lock(atomic, lock) \
 403                __cond_lock(lock, _atomic_dec_and_lock(atomic, lock))
 404
 405#endif /* __LINUX_SPINLOCK_H */
 406