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 #define spin_is_contended(lock) __raw_spin_is_contended(&(lock)->raw_lock)
 128 #endif
 129
 130 /**
 131  * spin_unlock_wait - wait until the spinlock gets unlocked
 132  * @lock: the spinlock in question.
 133  */
 134 #define spin_unlock_wait(lock)  __raw_spin_unlock_wait(&(lock)->raw_lock)
 135
 136 /*
 137  * Pull the _spin_*()/_read_*()/_write_*() functions/declarations:
 138  */
 139 #if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
 140 # include <linux/spinlock_api_smp.h>
 141 #else
 142 # include <linux/spinlock_api_up.h>
 143 #endif
 144
 145 #ifdef CONFIG_DEBUG_SPINLOCK
 146  extern void _raw_spin_lock(spinlock_t *lock);
 147 #define _raw_spin_lock_flags(lock, flags) _raw_spin_lock(lock)
 148  extern int _raw_spin_trylock(spinlock_t *lock);
 149  extern void _raw_spin_unlock(spinlock_t *lock);
 150  extern void _raw_read_lock(rwlock_t *lock);
 151  extern int _raw_read_trylock(rwlock_t *lock);
 152  extern void _raw_read_unlock(rwlock_t *lock);
 153  extern void _raw_write_lock(rwlock_t *lock);
 154  extern int _raw_write_trylock(rwlock_t *lock);
 155  extern void _raw_write_unlock(rwlock_t *lock);
 156 #else
 157 # define _raw_spin_lock(lock)           __raw_spin_lock(&(lock)->raw_lock)
 158 # define _raw_spin_lock_flags(lock, flags) \
 159                 __raw_spin_lock_flags(&(lock)->raw_lock, *(flags))
 160 # define _raw_spin_trylock(lock)        __raw_spin_trylock(&(lock)->raw_lock)
 161 # define _raw_spin_unlock(lock)         __raw_spin_unlock(&(lock)->raw_lock)
 162 # define _raw_read_lock(rwlock)         __raw_read_lock(&(rwlock)->raw_lock)
 163 # define _raw_read_trylock(rwlock)      __raw_read_trylock(&(rwlock)->raw_lock)
 164 # define _raw_read_unlock(rwlock)       __raw_read_unlock(&(rwlock)->raw_lock)
 165 # define _raw_write_lock(rwlock)        __raw_write_lock(&(rwlock)->raw_lock)
 166 # define _raw_write_trylock(rwlock)     __raw_write_trylock(&(rwlock)->raw_lock)
 167 # define _raw_write_unlock(rwlock)      __raw_write_unlock(&(rwlock)->raw_lock)
 168 #endif
 169
 170 #define read_can_lock(rwlock)           __raw_read_can_lock(&(rwlock)->raw_lock)
 171 #define write_can_lock(rwlock)          __raw_write_can_lock(&(rwlock)->raw_lock)
 172
 173 /*
 174  * Define the various spin_lock and rw_lock methods.  Note we define these
 175  * regardless of whether CONFIG_SMP or CONFIG_PREEMPT are set. The various
 176  * methods are defined as nops in the case they are not required.
 177  */
 178 #define spin_trylock(lock)              __cond_lock(lock, _spin_trylock(lock))
 179 #define read_trylock(lock)              __cond_lock(lock, _read_trylock(lock))
 180 #define write_trylock(lock)             __cond_lock(lock, _write_trylock(lock))
 181
 182 #define spin_lock(lock)                 _spin_lock(lock)
 183
 184 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 185 # define spin_lock_nested(lock, subclass) _spin_lock_nested(lock, subclass)
 186 #else
 187 # define spin_lock_nested(lock, subclass) _spin_lock(lock)
 188 #endif
 189
 190 #define write_lock(lock)                _write_lock(lock)
 191 #define read_lock(lock)                 _read_lock(lock)
 192
 193 #if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
 194
 195 #define spin_lock_irqsave(lock, flags)                  \
 196         do {                                            \
 197                 typecheck(unsigned long, flags);        \
 198                 flags = _spin_lock_irqsave(lock);       \
 199         } while (0)
 200 #define read_lock_irqsave(lock, flags)                  \
 201         do {                                            \
 202                 typecheck(unsigned long, flags);        \
 203                 flags = _read_lock_irqsave(lock);       \
 204         } while (0)
 205 #define write_lock_irqsave(lock, flags)                 \
 206         do {                                            \
 207                 typecheck(unsigned long, flags);        \
 208                 flags = _write_lock_irqsave(lock);      \
 209         } while (0)
 210
 211 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 212 #define spin_lock_irqsave_nested(lock, flags, subclass)                 \
 213         do {                                                            \
 214                 typecheck(unsigned long, flags);                        \
 215                 flags = _spin_lock_irqsave_nested(lock, subclass);      \
 216         } while (0)
 217 #else
 218 #define spin_lock_irqsave_nested(lock, flags, subclass)                 \
 219         do {                                                            \
 220                 typecheck(unsigned long, flags);                        \
 221                 flags = _spin_lock_irqsave(lock);                       \
 222         } while (0)
 223 #endif
 224
 225 #else
 226
 227 #define spin_lock_irqsave(lock, flags)                  \
 228         do {                                            \
 229                 typecheck(unsigned long, flags);        \
 230                 _spin_lock_irqsave(lock, flags);        \
 231         } while (0)
 232 #define read_lock_irqsave(lock, flags)                  \
 233         do {                                            \
 234                 typecheck(unsigned long, flags);        \
 235                 _read_lock_irqsave(lock, flags);        \
 236         } while (0)
 237 #define write_lock_irqsave(lock, flags)                 \
 238         do {                                            \
 239                 typecheck(unsigned long, flags);        \
 240                 _write_lock_irqsave(lock, flags);       \
 241         } while (0)
 242 #define spin_lock_irqsave_nested(lock, flags, subclass) \
 243         spin_lock_irqsave(lock, flags)
 244
 245 #endif
 246
 247 #define spin_lock_irq(lock)             _spin_lock_irq(lock)
 248 #define spin_lock_bh(lock)              _spin_lock_bh(lock)
 249
 250 #define read_lock_irq(lock)             _read_lock_irq(lock)
 251 #define read_lock_bh(lock)              _read_lock_bh(lock)
 252
 253 #define write_lock_irq(lock)            _write_lock_irq(lock)
 254 #define write_lock_bh(lock)             _write_lock_bh(lock)
 255
 256 /*
 257  * We inline the unlock functions in the nondebug case:
 258  */
 259 #if defined(CONFIG_DEBUG_SPINLOCK) || defined(CONFIG_PREEMPT) || \
 260         !defined(CONFIG_SMP)
 261 # define spin_unlock(lock)              _spin_unlock(lock)
 262 # define read_unlock(lock)              _read_unlock(lock)
 263 # define write_unlock(lock)             _write_unlock(lock)
 264 # define spin_unlock_irq(lock)          _spin_unlock_irq(lock)
 265 # define read_unlock_irq(lock)          _read_unlock_irq(lock)
 266 # define write_unlock_irq(lock)         _write_unlock_irq(lock)
 267 #else
 268 # define spin_unlock(lock) \
 269     do {__raw_spin_unlock(&(lock)->raw_lock); __release(lock); } while (0)
 270 # define read_unlock(lock) \
 271     do {__raw_read_unlock(&(lock)->raw_lock); __release(lock); } while (0)
 272 # define write_unlock(lock) \
 273     do {__raw_write_unlock(&(lock)->raw_lock); __release(lock); } while (0)
 274 # define spin_unlock_irq(lock)                  \
 275 do {                                            \
 276         __raw_spin_unlock(&(lock)->raw_lock);   \
 277         __release(lock);                        \
 278         local_irq_enable();                     \
 279 } while (0)
 280 # define read_unlock_irq(lock)                  \
 281 do {                                            \
 282         __raw_read_unlock(&(lock)->raw_lock);   \
 283         __release(lock);                        \
 284         local_irq_enable();                     \
 285 } while (0)
 286 # define write_unlock_irq(lock)                 \
 287 do {                                            \
 288         __raw_write_unlock(&(lock)->raw_lock);  \
 289         __release(lock);                        \
 290         local_irq_enable();                     \
 291 } while (0)
 292 #endif
 293
 294 #define spin_unlock_irqrestore(lock, flags)             \
 295         do {                                            \
 296                 typecheck(unsigned long, flags);        \
 297                 _spin_unlock_irqrestore(lock, flags);   \
 298         } while (0)
 299 #define spin_unlock_bh(lock)            _spin_unlock_bh(lock)
 300
 301 #define read_unlock_irqrestore(lock, flags)             \
 302         do {                                            \
 303                 typecheck(unsigned long, flags);        \
 304                 _read_unlock_irqrestore(lock, flags);   \
 305         } while (0)
 306 #define read_unlock_bh(lock)            _read_unlock_bh(lock)
 307
 308 #define write_unlock_irqrestore(lock, flags)            \
 309         do {                                            \
 310                 typecheck(unsigned long, flags);        \
 311                 _write_unlock_irqrestore(lock, flags);  \
 312         } while (0)
 313 #define write_unlock_bh(lock)           _write_unlock_bh(lock)
 314
 315 #define spin_trylock_bh(lock)   __cond_lock(lock, _spin_trylock_bh(lock))
 316
 317 #define spin_trylock_irq(lock) \
 318 ({ \
 319         local_irq_disable(); \
 320         spin_trylock(lock) ? \
 321         1 : ({ local_irq_enable(); 0;  }); \
 322 })
 323
 324 #define spin_trylock_irqsave(lock, flags) \
 325 ({ \
 326         local_irq_save(flags); \
 327         spin_trylock(lock) ? \
 328         1 : ({ local_irq_restore(flags); 0; }); \
 329 })
 330
 331 #define write_trylock_irqsave(lock, flags) \
 332 ({ \
 333         local_irq_save(flags); \
 334         write_trylock(lock) ? \
 335         1 : ({ local_irq_restore(flags); 0; }); \
 336 })
 337
 338 /*
 339  * Pull the atomic_t declaration:
 340  * (asm-mips/atomic.h needs above definitions)
 341  */
 342 #include <asm/atomic.h>
 343 /**
 344  * atomic_dec_and_lock - lock on reaching reference count zero
 345  * @atomic: the atomic counter
 346  * @lock: the spinlock in question
 347  *
 348  * Decrements @atomic by 1.  If the result is 0, returns true and locks
 349  * @lock.  Returns false for all other cases.
 350  */
 351 extern int _atomic_dec_and_lock(atomic_t *atomic, spinlock_t *lock);
 352 #define atomic_dec_and_lock(atomic, lock) \
 353                 __cond_lock(lock, _atomic_dec_and_lock(atomic, lock))
 354
 355 /**
 356  * spin_can_lock - would spin_trylock() succeed?
 357  * @lock: the spinlock in question.
 358  */
 359 #define spin_can_lock(lock)     (!spin_is_locked(lock))
 360
 361 #endif /* __LINUX_SPINLOCK_H */