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 /**
 136  * spin_unlock_wait - wait until the spinlock gets unlocked
 137  * @lock: the spinlock in question.
 138  */
 139 #define spin_unlock_wait(lock)  __raw_spin_unlock_wait(&(lock)->raw_lock)
 140
 141 /*
 142  * Pull the _spin_*()/_read_*()/_write_*() functions/declarations:
 143  */
 144 #if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
 145 # include <linux/spinlock_api_smp.h>
 146 #else
 147 # include <linux/spinlock_api_up.h>
 148 #endif
 149
 150 #ifdef CONFIG_DEBUG_SPINLOCK
 151  extern void _raw_spin_lock(spinlock_t *lock);
 152 #define _raw_spin_lock_flags(lock, flags) _raw_spin_lock(lock)
 153  extern int _raw_spin_trylock(spinlock_t *lock);
 154  extern void _raw_spin_unlock(spinlock_t *lock);
 155  extern void _raw_read_lock(rwlock_t *lock);
 156  extern int _raw_read_trylock(rwlock_t *lock);
 157  extern void _raw_read_unlock(rwlock_t *lock);
 158  extern void _raw_write_lock(rwlock_t *lock);
 159  extern int _raw_write_trylock(rwlock_t *lock);
 160  extern void _raw_write_unlock(rwlock_t *lock);
 161 #else
 162 # define _raw_spin_lock(lock)           __raw_spin_lock(&(lock)->raw_lock)
 163 # define _raw_spin_lock_flags(lock, flags) \
 164                 __raw_spin_lock_flags(&(lock)->raw_lock, *(flags))
 165 # define _raw_spin_trylock(lock)        __raw_spin_trylock(&(lock)->raw_lock)
 166 # define _raw_spin_unlock(lock)         __raw_spin_unlock(&(lock)->raw_lock)
 167 # define _raw_read_lock(rwlock)         __raw_read_lock(&(rwlock)->raw_lock)
 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_trylock(rwlock)     __raw_write_trylock(&(rwlock)->raw_lock)
 172 # define _raw_write_unlock(rwlock)      __raw_write_unlock(&(rwlock)->raw_lock)
 173 #endif
 174
 175 #define read_can_lock(rwlock)           __raw_read_can_lock(&(rwlock)->raw_lock)
 176 #define write_can_lock(rwlock)          __raw_write_can_lock(&(rwlock)->raw_lock)
 177
 178 /*
 179  * Define the various spin_lock and rw_lock methods.  Note we define these
 180  * regardless of whether CONFIG_SMP or CONFIG_PREEMPT are set. The various
 181  * methods are defined as nops in the case they are not required.
 182  */
 183 #define spin_trylock(lock)              __cond_lock(lock, _spin_trylock(lock))
 184 #define read_trylock(lock)              __cond_lock(lock, _read_trylock(lock))
 185 #define write_trylock(lock)             __cond_lock(lock, _write_trylock(lock))
 186
 187 #define spin_lock(lock)                 _spin_lock(lock)
 188
 189 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 190 # define spin_lock_nested(lock, subclass) _spin_lock_nested(lock, subclass)
 191 # define spin_lock_nest_lock(lock, nest_lock)                           \
 192          do {                                                           \
 193                  typecheck(struct lockdep_map *, &(nest_lock)->dep_map);\
 194                  _spin_lock_nest_lock(lock, &(nest_lock)->dep_map);     \
 195          } while (0)
 196 #else
 197 # define spin_lock_nested(lock, subclass) _spin_lock(lock)
 198 # define spin_lock_nest_lock(lock, nest_lock) _spin_lock(lock)
 199 #endif
 200
 201 #define write_lock(lock)                _write_lock(lock)
 202 #define read_lock(lock)                 _read_lock(lock)
 203
 204 #if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
 205
 206 #define spin_lock_irqsave(lock, flags)                  \
 207         do {                                            \
 208                 typecheck(unsigned long, flags);        \
 209                 flags = _spin_lock_irqsave(lock);       \
 210         } while (0)
 211 #define read_lock_irqsave(lock, flags)                  \
 212         do {                                            \
 213                 typecheck(unsigned long, flags);        \
 214                 flags = _read_lock_irqsave(lock);       \
 215         } while (0)
 216 #define write_lock_irqsave(lock, flags)                 \
 217         do {                                            \
 218                 typecheck(unsigned long, flags);        \
 219                 flags = _write_lock_irqsave(lock);      \
 220         } while (0)
 221
 222 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 223 #define spin_lock_irqsave_nested(lock, flags, subclass)                 \
 224         do {                                                            \
 225                 typecheck(unsigned long, flags);                        \
 226                 flags = _spin_lock_irqsave_nested(lock, subclass);      \
 227         } while (0)
 228 #else
 229 #define spin_lock_irqsave_nested(lock, flags, subclass)                 \
 230         do {                                                            \
 231                 typecheck(unsigned long, flags);                        \
 232                 flags = _spin_lock_irqsave(lock);                       \
 233         } while (0)
 234 #endif
 235
 236 #else
 237
 238 #define spin_lock_irqsave(lock, flags)                  \
 239         do {                                            \
 240                 typecheck(unsigned long, flags);        \
 241                 _spin_lock_irqsave(lock, flags);        \
 242         } while (0)
 243 #define read_lock_irqsave(lock, flags)                  \
 244         do {                                            \
 245                 typecheck(unsigned long, flags);        \
 246                 _read_lock_irqsave(lock, flags);        \
 247         } while (0)
 248 #define write_lock_irqsave(lock, flags)                 \
 249         do {                                            \
 250                 typecheck(unsigned long, flags);        \
 251                 _write_lock_irqsave(lock, flags);       \
 252         } while (0)
 253 #define spin_lock_irqsave_nested(lock, flags, subclass) \
 254         spin_lock_irqsave(lock, flags)
 255
 256 #endif
 257
 258 #define spin_lock_irq(lock)             _spin_lock_irq(lock)
 259 #define spin_lock_bh(lock)              _spin_lock_bh(lock)
 260
 261 #define read_lock_irq(lock)             _read_lock_irq(lock)
 262 #define read_lock_bh(lock)              _read_lock_bh(lock)
 263
 264 #define write_lock_irq(lock)            _write_lock_irq(lock)
 265 #define write_lock_bh(lock)             _write_lock_bh(lock)
 266
 267 /*
 268  * We inline the unlock functions in the nondebug case:
 269  */
 270 #if defined(CONFIG_DEBUG_SPINLOCK) || defined(CONFIG_PREEMPT) || \
 271         !defined(CONFIG_SMP)
 272 # define spin_unlock(lock)              _spin_unlock(lock)
 273 # define read_unlock(lock)              _read_unlock(lock)
 274 # define write_unlock(lock)             _write_unlock(lock)
 275 # define spin_unlock_irq(lock)          _spin_unlock_irq(lock)
 276 # define read_unlock_irq(lock)          _read_unlock_irq(lock)
 277 # define write_unlock_irq(lock)         _write_unlock_irq(lock)
 278 #else
 279 # define spin_unlock(lock) \
 280     do {__raw_spin_unlock(&(lock)->raw_lock); __release(lock); } while (0)
 281 # define read_unlock(lock) \
 282     do {__raw_read_unlock(&(lock)->raw_lock); __release(lock); } while (0)
 283 # define write_unlock(lock) \
 284     do {__raw_write_unlock(&(lock)->raw_lock); __release(lock); } while (0)
 285 # define spin_unlock_irq(lock)                  \
 286 do {                                            \
 287         __raw_spin_unlock(&(lock)->raw_lock);   \
 288         __release(lock);                        \
 289         local_irq_enable();                     \
 290 } while (0)
 291 # define read_unlock_irq(lock)                  \
 292 do {                                            \
 293         __raw_read_unlock(&(lock)->raw_lock);   \
 294         __release(lock);                        \
 295         local_irq_enable();                     \
 296 } while (0)
 297 # define write_unlock_irq(lock)                 \
 298 do {                                            \
 299         __raw_write_unlock(&(lock)->raw_lock);  \
 300         __release(lock);                        \
 301         local_irq_enable();                     \
 302 } while (0)
 303 #endif
 304
 305 #define spin_unlock_irqrestore(lock, flags)             \
 306         do {                                            \
 307                 typecheck(unsigned long, flags);        \
 308                 _spin_unlock_irqrestore(lock, flags);   \
 309         } while (0)
 310 #define spin_unlock_bh(lock)            _spin_unlock_bh(lock)
 311
 312 #define read_unlock_irqrestore(lock, flags)             \
 313         do {                                            \
 314                 typecheck(unsigned long, flags);        \
 315                 _read_unlock_irqrestore(lock, flags);   \
 316         } while (0)
 317 #define read_unlock_bh(lock)            _read_unlock_bh(lock)
 318
 319 #define write_unlock_irqrestore(lock, flags)            \
 320         do {                                            \
 321                 typecheck(unsigned long, flags);        \
 322                 _write_unlock_irqrestore(lock, flags);  \
 323         } while (0)
 324 #define write_unlock_bh(lock)           _write_unlock_bh(lock)
 325
 326 #define spin_trylock_bh(lock)   __cond_lock(lock, _spin_trylock_bh(lock))
 327
 328 #define spin_trylock_irq(lock) \
 329 ({ \
 330         local_irq_disable(); \
 331         spin_trylock(lock) ? \
 332         1 : ({ local_irq_enable(); 0;  }); \
 333 })
 334
 335 #define spin_trylock_irqsave(lock, flags) \
 336 ({ \
 337         local_irq_save(flags); \
 338         spin_trylock(lock) ? \
 339         1 : ({ local_irq_restore(flags); 0; }); \
 340 })
 341
 342 #define write_trylock_irqsave(lock, flags) \
 343 ({ \
 344         local_irq_save(flags); \
 345         write_trylock(lock) ? \
 346         1 : ({ local_irq_restore(flags); 0; }); \
 347 })
 348
 349 /*
 350  * Pull the atomic_t declaration:
 351  * (asm-mips/atomic.h needs above definitions)
 352  */
 353 #include <asm/atomic.h>
 354 /**
 355  * atomic_dec_and_lock - lock on reaching reference count zero
 356  * @atomic: the atomic counter
 357  * @lock: the spinlock in question
 358  *
 359  * Decrements @atomic by 1.  If the result is 0, returns true and locks
 360  * @lock.  Returns false for all other cases.
 361  */
 362 extern int _atomic_dec_and_lock(atomic_t *atomic, spinlock_t *lock);
 363 #define atomic_dec_and_lock(atomic, lock) \
 364                 __cond_lock(lock, _atomic_dec_and_lock(atomic, lock))
 365
 366 /**
 367  * spin_can_lock - would spin_trylock() succeed?
 368  * @lock: the spinlock in question.
 369  */
 370 #define spin_can_lock(lock)     (!spin_is_locked(lock))
 371
 372 #endif /* __LINUX_SPINLOCK_H */