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 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
  82 extern 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)                                   \
  97 do {                                                            \
  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)                                      \
 112 do {                                                            \
 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
 137 static 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 /*
 147  * Pull the _spin_*()/_read_*()/_write_*() functions/declarations:
 148  */
 149 #if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
 150 # include <linux/spinlock_api_smp.h>
 151 #else
 152 # include <linux/spinlock_api_up.h>
 153 #endif
 154
 155 #ifdef CONFIG_DEBUG_SPINLOCK
 156  extern void _raw_spin_lock(spinlock_t *lock);
 157 #define _raw_spin_lock_flags(lock, flags) _raw_spin_lock(lock)
 158  extern int _raw_spin_trylock(spinlock_t *lock);
 159  extern void _raw_spin_unlock(spinlock_t *lock);
 160  extern void _raw_read_lock(rwlock_t *lock);
 161 #define _raw_read_lock_flags(lock, flags) _raw_read_lock(lock)
 162  extern int _raw_read_trylock(rwlock_t *lock);
 163  extern void _raw_read_unlock(rwlock_t *lock);
 164  extern void _raw_write_lock(rwlock_t *lock);
 165 #define _raw_write_lock_flags(lock, flags) _raw_write_lock(lock)
 166  extern int _raw_write_trylock(rwlock_t *lock);
 167  extern void _raw_write_unlock(rwlock_t *lock);
 168 #else
 169 # define _raw_spin_lock(lock)           __raw_spin_lock(&(lock)->raw_lock)
 170 # define _raw_spin_lock_flags(lock, flags) \
 171                 __raw_spin_lock_flags(&(lock)->raw_lock, *(flags))
 172 # define _raw_spin_trylock(lock)        __raw_spin_trylock(&(lock)->raw_lock)
 173 # define _raw_spin_unlock(lock)         __raw_spin_unlock(&(lock)->raw_lock)
 174 # define _raw_read_lock(rwlock)         __raw_read_lock(&(rwlock)->raw_lock)
 175 # define _raw_read_lock_flags(lock, flags) \
 176                 __raw_read_lock_flags(&(lock)->raw_lock, *(flags))
 177 # define _raw_read_trylock(rwlock)      __raw_read_trylock(&(rwlock)->raw_lock)
 178 # define _raw_read_unlock(rwlock)       __raw_read_unlock(&(rwlock)->raw_lock)
 179 # define _raw_write_lock(rwlock)        __raw_write_lock(&(rwlock)->raw_lock)
 180 # define _raw_write_lock_flags(lock, flags) \
 181                 __raw_write_lock_flags(&(lock)->raw_lock, *(flags))
 182 # define _raw_write_trylock(rwlock)     __raw_write_trylock(&(rwlock)->raw_lock)
 183 # define _raw_write_unlock(rwlock)      __raw_write_unlock(&(rwlock)->raw_lock)
 184 #endif
 185
 186 #define read_can_lock(rwlock)           __raw_read_can_lock(&(rwlock)->raw_lock)
 187 #define write_can_lock(rwlock)          __raw_write_can_lock(&(rwlock)->raw_lock)
 188
 189 /*
 190  * Define the various spin_lock and rw_lock methods.  Note we define these
 191  * regardless of whether CONFIG_SMP or CONFIG_PREEMPT are set. The various
 192  * methods are defined as nops in the case they are not required.
 193  */
 194 #define spin_trylock(lock)              __cond_lock(lock, _spin_trylock(lock))
 195 #define read_trylock(lock)              __cond_lock(lock, _read_trylock(lock))
 196 #define write_trylock(lock)             __cond_lock(lock, _write_trylock(lock))
 197
 198 #define spin_lock(lock)                 _spin_lock(lock)
 199
 200 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 201 # define spin_lock_nested(lock, subclass) _spin_lock_nested(lock, subclass)
 202 # define spin_lock_nest_lock(lock, nest_lock)                           \
 203          do {                                                           \
 204                  typecheck(struct lockdep_map *, &(nest_lock)->dep_map);\
 205                  _spin_lock_nest_lock(lock, &(nest_lock)->dep_map);     \
 206          } while (0)
 207 #else
 208 # define spin_lock_nested(lock, subclass) _spin_lock(lock)
 209 # define spin_lock_nest_lock(lock, nest_lock) _spin_lock(lock)
 210 #endif
 211
 212 #define write_lock(lock)                _write_lock(lock)
 213 #define read_lock(lock)                 _read_lock(lock)
 214
 215 #if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
 216
 217 #define spin_lock_irqsave(lock, flags)                  \
 218         do {                                            \
 219                 typecheck(unsigned long, flags);        \
 220                 flags = _spin_lock_irqsave(lock);       \
 221         } while (0)
 222 #define read_lock_irqsave(lock, flags)                  \
 223         do {                                            \
 224                 typecheck(unsigned long, flags);        \
 225                 flags = _read_lock_irqsave(lock);       \
 226         } while (0)
 227 #define write_lock_irqsave(lock, flags)                 \
 228         do {                                            \
 229                 typecheck(unsigned long, flags);        \
 230                 flags = _write_lock_irqsave(lock);      \
 231         } while (0)
 232
 233 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 234 #define spin_lock_irqsave_nested(lock, flags, subclass)                 \
 235         do {                                                            \
 236                 typecheck(unsigned long, flags);                        \
 237                 flags = _spin_lock_irqsave_nested(lock, subclass);      \
 238         } while (0)
 239 #else
 240 #define spin_lock_irqsave_nested(lock, flags, subclass)                 \
 241         do {                                                            \
 242                 typecheck(unsigned long, flags);                        \
 243                 flags = _spin_lock_irqsave(lock);                       \
 244         } while (0)
 245 #endif
 246
 247 #else
 248
 249 #define spin_lock_irqsave(lock, flags)                  \
 250         do {                                            \
 251                 typecheck(unsigned long, flags);        \
 252                 _spin_lock_irqsave(lock, flags);        \
 253         } while (0)
 254 #define read_lock_irqsave(lock, flags)                  \
 255         do {                                            \
 256                 typecheck(unsigned long, flags);        \
 257                 _read_lock_irqsave(lock, flags);        \
 258         } while (0)
 259 #define write_lock_irqsave(lock, flags)                 \
 260         do {                                            \
 261                 typecheck(unsigned long, flags);        \
 262                 _write_lock_irqsave(lock, flags);       \
 263         } while (0)
 264 #define spin_lock_irqsave_nested(lock, flags, subclass) \
 265         spin_lock_irqsave(lock, flags)
 266
 267 #endif
 268
 269 #define spin_lock_irq(lock)             _spin_lock_irq(lock)
 270 #define spin_lock_bh(lock)              _spin_lock_bh(lock)
 271
 272 #define read_lock_irq(lock)             _read_lock_irq(lock)
 273 #define read_lock_bh(lock)              _read_lock_bh(lock)
 274
 275 #define write_lock_irq(lock)            _write_lock_irq(lock)
 276 #define write_lock_bh(lock)             _write_lock_bh(lock)
 277
 278 /*
 279  * We inline the unlock functions in the nondebug case:
 280  */
 281 #if defined(CONFIG_DEBUG_SPINLOCK) || defined(CONFIG_PREEMPT) || \
 282         !defined(CONFIG_SMP)
 283 # define spin_unlock(lock)              _spin_unlock(lock)
 284 # define read_unlock(lock)              _read_unlock(lock)
 285 # define write_unlock(lock)             _write_unlock(lock)
 286 # define spin_unlock_irq(lock)          _spin_unlock_irq(lock)
 287 # define read_unlock_irq(lock)          _read_unlock_irq(lock)
 288 # define write_unlock_irq(lock)         _write_unlock_irq(lock)
 289 #else
 290 # define spin_unlock(lock) \
 291     do {__raw_spin_unlock(&(lock)->raw_lock); __release(lock); } while (0)
 292 # define read_unlock(lock) \
 293     do {__raw_read_unlock(&(lock)->raw_lock); __release(lock); } while (0)
 294 # define write_unlock(lock) \
 295     do {__raw_write_unlock(&(lock)->raw_lock); __release(lock); } while (0)
 296 # define spin_unlock_irq(lock)                  \
 297 do {                                            \
 298         __raw_spin_unlock(&(lock)->raw_lock);   \
 299         __release(lock);                        \
 300         local_irq_enable();                     \
 301 } while (0)
 302 # define read_unlock_irq(lock)                  \
 303 do {                                            \
 304         __raw_read_unlock(&(lock)->raw_lock);   \
 305         __release(lock);                        \
 306         local_irq_enable();                     \
 307 } while (0)
 308 # define write_unlock_irq(lock)                 \
 309 do {                                            \
 310         __raw_write_unlock(&(lock)->raw_lock);  \
 311         __release(lock);                        \
 312         local_irq_enable();                     \
 313 } while (0)
 314 #endif
 315
 316 #define spin_unlock_irqrestore(lock, flags)             \
 317         do {                                            \
 318                 typecheck(unsigned long, flags);        \
 319                 _spin_unlock_irqrestore(lock, flags);   \
 320         } while (0)
 321 #define spin_unlock_bh(lock)            _spin_unlock_bh(lock)
 322
 323 #define read_unlock_irqrestore(lock, flags)             \
 324         do {                                            \
 325                 typecheck(unsigned long, flags);        \
 326                 _read_unlock_irqrestore(lock, flags);   \
 327         } while (0)
 328 #define read_unlock_bh(lock)            _read_unlock_bh(lock)
 329
 330 #define write_unlock_irqrestore(lock, flags)            \
 331         do {                                            \
 332                 typecheck(unsigned long, flags);        \
 333                 _write_unlock_irqrestore(lock, flags);  \
 334         } while (0)
 335 #define write_unlock_bh(lock)           _write_unlock_bh(lock)
 336
 337 #define spin_trylock_bh(lock)   __cond_lock(lock, _spin_trylock_bh(lock))
 338
 339 #define spin_trylock_irq(lock) \
 340 ({ \
 341         local_irq_disable(); \
 342         spin_trylock(lock) ? \
 343         1 : ({ local_irq_enable(); 0;  }); \
 344 })
 345
 346 #define spin_trylock_irqsave(lock, flags) \
 347 ({ \
 348         local_irq_save(flags); \
 349         spin_trylock(lock) ? \
 350         1 : ({ local_irq_restore(flags); 0; }); \
 351 })
 352
 353 #define write_trylock_irqsave(lock, flags) \
 354 ({ \
 355         local_irq_save(flags); \
 356         write_trylock(lock) ? \
 357         1 : ({ local_irq_restore(flags); 0; }); \
 358 })
 359
 360 /*
 361  * Pull the atomic_t declaration:
 362  * (asm-mips/atomic.h needs above definitions)
 363  */
 364 #include <asm/atomic.h>
 365 /**
 366  * atomic_dec_and_lock - lock on reaching reference count zero
 367  * @atomic: the atomic counter
 368  * @lock: the spinlock in question
 369  *
 370  * Decrements @atomic by 1.  If the result is 0, returns true and locks
 371  * @lock.  Returns false for all other cases.
 372  */
 373 extern int _atomic_dec_and_lock(atomic_t *atomic, spinlock_t *lock);
 374 #define atomic_dec_and_lock(atomic, lock) \
 375                 __cond_lock(lock, _atomic_dec_and_lock(atomic, lock))
 376
 377 /**
 378  * spin_can_lock - would spin_trylock() succeed?
 379  * @lock: the spinlock in question.
 380  */
 381 #define spin_can_lock(lock)     (!spin_is_locked(lock))
 382
 383 #endif /* __LINUX_SPINLOCK_H */