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/preempt.h>
  50 #include <linux/linkage.h>
  51 #include <linux/compiler.h>
  52 #include <linux/thread_info.h>
  53 #include <linux/kernel.h>
  54 #include <linux/stringify.h>
  55 #include <linux/bottom_half.h>
  56
  57 #include <asm/system.h>
  58
  59 /*
  60  * Must define these before including other files, inline functions need them
  61  */
  62 #define LOCK_SECTION_NAME ".text.lock."KBUILD_BASENAME
  63
  64 #define LOCK_SECTION_START(extra)               \
  65         ".subsection 1\n\t"                     \
  66         extra                                   \
  67         ".ifndef " LOCK_SECTION_NAME "\n\t"     \
  68         LOCK_SECTION_NAME ":\n\t"               \
  69         ".endif\n"
  70
  71 #define LOCK_SECTION_END                        \
  72         ".previous\n\t"
  73
  74 #define __lockfunc __attribute__((section(".spinlock.text")))
  75
  76 /*
  77  * Pull the raw_spinlock_t and raw_rwlock_t definitions:
  78  */
  79 #include <linux/spinlock_types.h>
  80
  81 extern int __lockfunc generic__raw_read_trylock(raw_rwlock_t *lock);
  82
  83 /*
  84  * Pull the __raw*() functions/declarations (UP-nondebug doesnt 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 __spin_lock_init(spinlock_t *lock, const char *name,
  94                                struct lock_class_key *key);
  95 # define spin_lock_init(lock)                                   \
  96 do {                                                            \
  97         static struct lock_class_key __key;                     \
  98                                                                 \
  99         __spin_lock_init((lock), #lock, &__key);                \
 100 } while (0)
 101
 102 #else
 103 # define spin_lock_init(lock)                                   \
 104         do { *(lock) = SPIN_LOCK_UNLOCKED; } while (0)
 105 #endif
 106
 107 #ifdef CONFIG_DEBUG_SPINLOCK
 108   extern void __rwlock_init(rwlock_t *lock, const char *name,
 109                             struct lock_class_key *key);
 110 # define rwlock_init(lock)                                      \
 111 do {                                                            \
 112         static struct lock_class_key __key;                     \
 113                                                                 \
 114         __rwlock_init((lock), #lock, &__key);                   \
 115 } while (0)
 116 #else
 117 # define rwlock_init(lock)                                      \
 118         do { *(lock) = RW_LOCK_UNLOCKED; } while (0)
 119 #endif
 120
 121 #define spin_is_locked(lock)    __raw_spin_is_locked(&(lock)->raw_lock)
 122
 123 #ifdef CONFIG_GENERIC_LOCKBREAK
 124 #define spin_is_contended(lock) ((lock)->break_lock)
 125 #else
 126 #define spin_is_contended(lock) __raw_spin_is_contended(&(lock)->raw_lock)
 127 #endif
 128
 129 /**
 130  * spin_unlock_wait - wait until the spinlock gets unlocked
 131  * @lock: the spinlock in question.
 132  */
 133 #define spin_unlock_wait(lock)  __raw_spin_unlock_wait(&(lock)->raw_lock)
 134
 135 /*
 136  * Pull the _spin_*()/_read_*()/_write_*() functions/declarations:
 137  */
 138 #if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
 139 # include <linux/spinlock_api_smp.h>
 140 #else
 141 # include <linux/spinlock_api_up.h>
 142 #endif
 143
 144 #ifdef CONFIG_DEBUG_SPINLOCK
 145  extern void _raw_spin_lock(spinlock_t *lock);
 146 #define _raw_spin_lock_flags(lock, flags) _raw_spin_lock(lock)
 147  extern int _raw_spin_trylock(spinlock_t *lock);
 148  extern void _raw_spin_unlock(spinlock_t *lock);
 149  extern void _raw_read_lock(rwlock_t *lock);
 150  extern int _raw_read_trylock(rwlock_t *lock);
 151  extern void _raw_read_unlock(rwlock_t *lock);
 152  extern void _raw_write_lock(rwlock_t *lock);
 153  extern int _raw_write_trylock(rwlock_t *lock);
 154  extern void _raw_write_unlock(rwlock_t *lock);
 155 #else
 156 # define _raw_spin_lock(lock)           __raw_spin_lock(&(lock)->raw_lock)
 157 # define _raw_spin_lock_flags(lock, flags) \
 158                 __raw_spin_lock_flags(&(lock)->raw_lock, *(flags))
 159 # define _raw_spin_trylock(lock)        __raw_spin_trylock(&(lock)->raw_lock)
 160 # define _raw_spin_unlock(lock)         __raw_spin_unlock(&(lock)->raw_lock)
 161 # define _raw_read_lock(rwlock)         __raw_read_lock(&(rwlock)->raw_lock)
 162 # define _raw_read_trylock(rwlock)      __raw_read_trylock(&(rwlock)->raw_lock)
 163 # define _raw_read_unlock(rwlock)       __raw_read_unlock(&(rwlock)->raw_lock)
 164 # define _raw_write_lock(rwlock)        __raw_write_lock(&(rwlock)->raw_lock)
 165 # define _raw_write_trylock(rwlock)     __raw_write_trylock(&(rwlock)->raw_lock)
 166 # define _raw_write_unlock(rwlock)      __raw_write_unlock(&(rwlock)->raw_lock)
 167 #endif
 168
 169 #define read_can_lock(rwlock)           __raw_read_can_lock(&(rwlock)->raw_lock)
 170 #define write_can_lock(rwlock)          __raw_write_can_lock(&(rwlock)->raw_lock)
 171
 172 /*
 173  * Define the various spin_lock and rw_lock methods.  Note we define these
 174  * regardless of whether CONFIG_SMP or CONFIG_PREEMPT are set. The various
 175  * methods are defined as nops in the case they are not required.
 176  */
 177 #define spin_trylock(lock)              __cond_lock(lock, _spin_trylock(lock))
 178 #define read_trylock(lock)              __cond_lock(lock, _read_trylock(lock))
 179 #define write_trylock(lock)             __cond_lock(lock, _write_trylock(lock))
 180
 181 #define spin_lock(lock)                 _spin_lock(lock)
 182
 183 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 184 # define spin_lock_nested(lock, subclass) _spin_lock_nested(lock, subclass)
 185 #else
 186 # define spin_lock_nested(lock, subclass) _spin_lock(lock)
 187 #endif
 188
 189 #define write_lock(lock)                _write_lock(lock)
 190 #define read_lock(lock)                 _read_lock(lock)
 191
 192 #if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
 193
 194 #define spin_lock_irqsave(lock, flags)  flags = _spin_lock_irqsave(lock)
 195 #define read_lock_irqsave(lock, flags)  flags = _read_lock_irqsave(lock)
 196 #define write_lock_irqsave(lock, flags) flags = _write_lock_irqsave(lock)
 197
 198 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 199 #define spin_lock_irqsave_nested(lock, flags, subclass) \
 200         flags = _spin_lock_irqsave_nested(lock, subclass)
 201 #else
 202 #define spin_lock_irqsave_nested(lock, flags, subclass) \
 203         flags = _spin_lock_irqsave(lock)
 204 #endif
 205
 206 #else
 207
 208 #define spin_lock_irqsave(lock, flags)  _spin_lock_irqsave(lock, flags)
 209 #define read_lock_irqsave(lock, flags)  _read_lock_irqsave(lock, flags)
 210 #define write_lock_irqsave(lock, flags) _write_lock_irqsave(lock, flags)
 211 #define spin_lock_irqsave_nested(lock, flags, subclass) \
 212         spin_lock_irqsave(lock, flags)
 213
 214 #endif
 215
 216 #define spin_lock_irq(lock)             _spin_lock_irq(lock)
 217 #define spin_lock_bh(lock)              _spin_lock_bh(lock)
 218
 219 #define read_lock_irq(lock)             _read_lock_irq(lock)
 220 #define read_lock_bh(lock)              _read_lock_bh(lock)
 221
 222 #define write_lock_irq(lock)            _write_lock_irq(lock)
 223 #define write_lock_bh(lock)             _write_lock_bh(lock)
 224
 225 /*
 226  * We inline the unlock functions in the nondebug case:
 227  */
 228 #if defined(CONFIG_DEBUG_SPINLOCK) || defined(CONFIG_PREEMPT) || \
 229         !defined(CONFIG_SMP)
 230 # define spin_unlock(lock)              _spin_unlock(lock)
 231 # define read_unlock(lock)              _read_unlock(lock)
 232 # define write_unlock(lock)             _write_unlock(lock)
 233 # define spin_unlock_irq(lock)          _spin_unlock_irq(lock)
 234 # define read_unlock_irq(lock)          _read_unlock_irq(lock)
 235 # define write_unlock_irq(lock)         _write_unlock_irq(lock)
 236 #else
 237 # define spin_unlock(lock) \
 238     do {__raw_spin_unlock(&(lock)->raw_lock); __release(lock); } while (0)
 239 # define read_unlock(lock) \
 240     do {__raw_read_unlock(&(lock)->raw_lock); __release(lock); } while (0)
 241 # define write_unlock(lock) \
 242     do {__raw_write_unlock(&(lock)->raw_lock); __release(lock); } while (0)
 243 # define spin_unlock_irq(lock)                  \
 244 do {                                            \
 245         __raw_spin_unlock(&(lock)->raw_lock);   \
 246         __release(lock);                        \
 247         local_irq_enable();                     \
 248 } while (0)
 249 # define read_unlock_irq(lock)                  \
 250 do {                                            \
 251         __raw_read_unlock(&(lock)->raw_lock);   \
 252         __release(lock);                        \
 253         local_irq_enable();                     \
 254 } while (0)
 255 # define write_unlock_irq(lock)                 \
 256 do {                                            \
 257         __raw_write_unlock(&(lock)->raw_lock);  \
 258         __release(lock);                        \
 259         local_irq_enable();                     \
 260 } while (0)
 261 #endif
 262
 263 #define spin_unlock_irqrestore(lock, flags) \
 264                                         _spin_unlock_irqrestore(lock, flags)
 265 #define spin_unlock_bh(lock)            _spin_unlock_bh(lock)
 266
 267 #define read_unlock_irqrestore(lock, flags) \
 268                                         _read_unlock_irqrestore(lock, flags)
 269 #define read_unlock_bh(lock)            _read_unlock_bh(lock)
 270
 271 #define write_unlock_irqrestore(lock, flags) \
 272                                         _write_unlock_irqrestore(lock, flags)
 273 #define write_unlock_bh(lock)           _write_unlock_bh(lock)
 274
 275 #define spin_trylock_bh(lock)   __cond_lock(lock, _spin_trylock_bh(lock))
 276
 277 #define spin_trylock_irq(lock) \
 278 ({ \
 279         local_irq_disable(); \
 280         spin_trylock(lock) ? \
 281         1 : ({ local_irq_enable(); 0;  }); \
 282 })
 283
 284 #define spin_trylock_irqsave(lock, flags) \
 285 ({ \
 286         local_irq_save(flags); \
 287         spin_trylock(lock) ? \
 288         1 : ({ local_irq_restore(flags); 0; }); \
 289 })
 290
 291 #define write_trylock_irqsave(lock, flags) \
 292 ({ \
 293         local_irq_save(flags); \
 294         write_trylock(lock) ? \
 295         1 : ({ local_irq_restore(flags); 0; }); \
 296 })
 297
 298 /*
 299  * Locks two spinlocks l1 and l2.
 300  * l1_first indicates if spinlock l1 should be taken first.
 301  */
 302 static inline void double_spin_lock(spinlock_t *l1, spinlock_t *l2,
 303                                     bool l1_first)
 304         __acquires(l1)
 305         __acquires(l2)
 306 {
 307         if (l1_first) {
 308                 spin_lock(l1);
 309                 spin_lock(l2);
 310         } else {
 311                 spin_lock(l2);
 312                 spin_lock(l1);
 313         }
 314 }
 315
 316 /*
 317  * Unlocks two spinlocks l1 and l2.
 318  * l1_taken_first indicates if spinlock l1 was taken first and therefore
 319  * should be released after spinlock l2.
 320  */
 321 static inline void double_spin_unlock(spinlock_t *l1, spinlock_t *l2,
 322                                       bool l1_taken_first)
 323         __releases(l1)
 324         __releases(l2)
 325 {
 326         if (l1_taken_first) {
 327                 spin_unlock(l2);
 328                 spin_unlock(l1);
 329         } else {
 330                 spin_unlock(l1);
 331                 spin_unlock(l2);
 332         }
 333 }
 334
 335 /*
 336  * Pull the atomic_t declaration:
 337  * (asm-mips/atomic.h needs above definitions)
 338  */
 339 #include <asm/atomic.h>
 340 /**
 341  * atomic_dec_and_lock - lock on reaching reference count zero
 342  * @atomic: the atomic counter
 343  * @lock: the spinlock in question
 344  *
 345  * Decrements @atomic by 1.  If the result is 0, returns true and locks
 346  * @lock.  Returns false for all other cases.
 347  */
 348 extern int _atomic_dec_and_lock(atomic_t *atomic, spinlock_t *lock);
 349 #define atomic_dec_and_lock(atomic, lock) \
 350                 __cond_lock(lock, _atomic_dec_and_lock(atomic, lock))
 351
 352 /**
 353  * spin_can_lock - would spin_trylock() succeed?
 354  * @lock: the spinlock in question.
 355  */
 356 #define spin_can_lock(lock)     (!spin_is_locked(lock))
 357
 358 #endif /* __LINUX_SPINLOCK_H */