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 fastcall __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 /**
 124  * spin_unlock_wait - wait until the spinlock gets unlocked
 125  * @lock: the spinlock in question.
 126  */
 127 #define spin_unlock_wait(lock)  __raw_spin_unlock_wait(&(lock)->raw_lock)
 128
 129 /*
 130  * Pull the _spin_*()/_read_*()/_write_*() functions/declarations:
 131  */
 132 #if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
 133 # include <linux/spinlock_api_smp.h>
 134 #else
 135 # include <linux/spinlock_api_up.h>
 136 #endif
 137
 138 #ifdef CONFIG_DEBUG_SPINLOCK
 139  extern void _raw_spin_lock(spinlock_t *lock);
 140 #define _raw_spin_lock_flags(lock, flags) _raw_spin_lock(lock)
 141  extern int _raw_spin_trylock(spinlock_t *lock);
 142  extern void _raw_spin_unlock(spinlock_t *lock);
 143  extern void _raw_read_lock(rwlock_t *lock);
 144  extern int _raw_read_trylock(rwlock_t *lock);
 145  extern void _raw_read_unlock(rwlock_t *lock);
 146  extern void _raw_write_lock(rwlock_t *lock);
 147  extern int _raw_write_trylock(rwlock_t *lock);
 148  extern void _raw_write_unlock(rwlock_t *lock);
 149 #else
 150 # define _raw_spin_lock(lock)           __raw_spin_lock(&(lock)->raw_lock)
 151 # define _raw_spin_lock_flags(lock, flags) \
 152                 __raw_spin_lock_flags(&(lock)->raw_lock, *(flags))
 153 # define _raw_spin_trylock(lock)        __raw_spin_trylock(&(lock)->raw_lock)
 154 # define _raw_spin_unlock(lock)         __raw_spin_unlock(&(lock)->raw_lock)
 155 # define _raw_read_lock(rwlock)         __raw_read_lock(&(rwlock)->raw_lock)
 156 # define _raw_read_trylock(rwlock)      __raw_read_trylock(&(rwlock)->raw_lock)
 157 # define _raw_read_unlock(rwlock)       __raw_read_unlock(&(rwlock)->raw_lock)
 158 # define _raw_write_lock(rwlock)        __raw_write_lock(&(rwlock)->raw_lock)
 159 # define _raw_write_trylock(rwlock)     __raw_write_trylock(&(rwlock)->raw_lock)
 160 # define _raw_write_unlock(rwlock)      __raw_write_unlock(&(rwlock)->raw_lock)
 161 #endif
 162
 163 #define read_can_lock(rwlock)           __raw_read_can_lock(&(rwlock)->raw_lock)
 164 #define write_can_lock(rwlock)          __raw_write_can_lock(&(rwlock)->raw_lock)
 165
 166 /*
 167  * Define the various spin_lock and rw_lock methods.  Note we define these
 168  * regardless of whether CONFIG_SMP or CONFIG_PREEMPT are set. The various
 169  * methods are defined as nops in the case they are not required.
 170  */
 171 #define spin_trylock(lock)              __cond_lock(lock, _spin_trylock(lock))
 172 #define read_trylock(lock)              __cond_lock(lock, _read_trylock(lock))
 173 #define write_trylock(lock)             __cond_lock(lock, _write_trylock(lock))
 174
 175 #define spin_lock(lock)                 _spin_lock(lock)
 176
 177 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 178 # define spin_lock_nested(lock, subclass) _spin_lock_nested(lock, subclass)
 179 #else
 180 # define spin_lock_nested(lock, subclass) _spin_lock(lock)
 181 #endif
 182
 183 #define write_lock(lock)                _write_lock(lock)
 184 #define read_lock(lock)                 _read_lock(lock)
 185
 186 #if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
 187
 188 #define spin_lock_irqsave(lock, flags)  flags = _spin_lock_irqsave(lock)
 189 #define read_lock_irqsave(lock, flags)  flags = _read_lock_irqsave(lock)
 190 #define write_lock_irqsave(lock, flags) flags = _write_lock_irqsave(lock)
 191
 192 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 193 #define spin_lock_irqsave_nested(lock, flags, subclass) \
 194         flags = _spin_lock_irqsave_nested(lock, subclass)
 195 #else
 196 #define spin_lock_irqsave_nested(lock, flags, subclass) \
 197         flags = _spin_lock_irqsave(lock)
 198 #endif
 199
 200 #else
 201
 202 #define spin_lock_irqsave(lock, flags)  _spin_lock_irqsave(lock, flags)
 203 #define read_lock_irqsave(lock, flags)  _read_lock_irqsave(lock, flags)
 204 #define write_lock_irqsave(lock, flags) _write_lock_irqsave(lock, flags)
 205 #define spin_lock_irqsave_nested(lock, flags, subclass) \
 206         spin_lock_irqsave(lock, flags)
 207
 208 #endif
 209
 210 #define spin_lock_irq(lock)             _spin_lock_irq(lock)
 211 #define spin_lock_bh(lock)              _spin_lock_bh(lock)
 212
 213 #define read_lock_irq(lock)             _read_lock_irq(lock)
 214 #define read_lock_bh(lock)              _read_lock_bh(lock)
 215
 216 #define write_lock_irq(lock)            _write_lock_irq(lock)
 217 #define write_lock_bh(lock)             _write_lock_bh(lock)
 218
 219 /*
 220  * We inline the unlock functions in the nondebug case:
 221  */
 222 #if defined(CONFIG_DEBUG_SPINLOCK) || defined(CONFIG_PREEMPT) || \
 223         !defined(CONFIG_SMP)
 224 # define spin_unlock(lock)              _spin_unlock(lock)
 225 # define read_unlock(lock)              _read_unlock(lock)
 226 # define write_unlock(lock)             _write_unlock(lock)
 227 # define spin_unlock_irq(lock)          _spin_unlock_irq(lock)
 228 # define read_unlock_irq(lock)          _read_unlock_irq(lock)
 229 # define write_unlock_irq(lock)         _write_unlock_irq(lock)
 230 #else
 231 # define spin_unlock(lock) \
 232     do {__raw_spin_unlock(&(lock)->raw_lock); __release(lock); } while (0)
 233 # define read_unlock(lock) \
 234     do {__raw_read_unlock(&(lock)->raw_lock); __release(lock); } while (0)
 235 # define write_unlock(lock) \
 236     do {__raw_write_unlock(&(lock)->raw_lock); __release(lock); } while (0)
 237 # define spin_unlock_irq(lock)                  \
 238 do {                                            \
 239         __raw_spin_unlock(&(lock)->raw_lock);   \
 240         __release(lock);                        \
 241         local_irq_enable();                     \
 242 } while (0)
 243 # define read_unlock_irq(lock)                  \
 244 do {                                            \
 245         __raw_read_unlock(&(lock)->raw_lock);   \
 246         __release(lock);                        \
 247         local_irq_enable();                     \
 248 } while (0)
 249 # define write_unlock_irq(lock)                 \
 250 do {                                            \
 251         __raw_write_unlock(&(lock)->raw_lock);  \
 252         __release(lock);                        \
 253         local_irq_enable();                     \
 254 } while (0)
 255 #endif
 256
 257 #define spin_unlock_irqrestore(lock, flags) \
 258                                         _spin_unlock_irqrestore(lock, flags)
 259 #define spin_unlock_bh(lock)            _spin_unlock_bh(lock)
 260
 261 #define read_unlock_irqrestore(lock, flags) \
 262                                         _read_unlock_irqrestore(lock, flags)
 263 #define read_unlock_bh(lock)            _read_unlock_bh(lock)
 264
 265 #define write_unlock_irqrestore(lock, flags) \
 266                                         _write_unlock_irqrestore(lock, flags)
 267 #define write_unlock_bh(lock)           _write_unlock_bh(lock)
 268
 269 #define spin_trylock_bh(lock)   __cond_lock(lock, _spin_trylock_bh(lock))
 270
 271 #define spin_trylock_irq(lock) \
 272 ({ \
 273         local_irq_disable(); \
 274         spin_trylock(lock) ? \
 275         1 : ({ local_irq_enable(); 0;  }); \
 276 })
 277
 278 #define spin_trylock_irqsave(lock, flags) \
 279 ({ \
 280         local_irq_save(flags); \
 281         spin_trylock(lock) ? \
 282         1 : ({ local_irq_restore(flags); 0; }); \
 283 })
 284
 285 /*
 286  * Locks two spinlocks l1 and l2.
 287  * l1_first indicates if spinlock l1 should be taken first.
 288  */
 289 static inline void double_spin_lock(spinlock_t *l1, spinlock_t *l2,
 290                                     bool l1_first)
 291         __acquires(l1)
 292         __acquires(l2)
 293 {
 294         if (l1_first) {
 295                 spin_lock(l1);
 296                 spin_lock(l2);
 297         } else {
 298                 spin_lock(l2);
 299                 spin_lock(l1);
 300         }
 301 }
 302
 303 /*
 304  * Unlocks two spinlocks l1 and l2.
 305  * l1_taken_first indicates if spinlock l1 was taken first and therefore
 306  * should be released after spinlock l2.
 307  */
 308 static inline void double_spin_unlock(spinlock_t *l1, spinlock_t *l2,
 309                                       bool l1_taken_first)
 310         __releases(l1)
 311         __releases(l2)
 312 {
 313         if (l1_taken_first) {
 314                 spin_unlock(l2);
 315                 spin_unlock(l1);
 316         } else {
 317                 spin_unlock(l1);
 318                 spin_unlock(l2);
 319         }
 320 }
 321
 322 /*
 323  * Pull the atomic_t declaration:
 324  * (asm-mips/atomic.h needs above definitions)
 325  */
 326 #include <asm/atomic.h>
 327 /**
 328  * atomic_dec_and_lock - lock on reaching reference count zero
 329  * @atomic: the atomic counter
 330  * @lock: the spinlock in question
 331  */
 332 extern int _atomic_dec_and_lock(atomic_t *atomic, spinlock_t *lock);
 333 #define atomic_dec_and_lock(atomic, lock) \
 334                 __cond_lock(lock, _atomic_dec_and_lock(atomic, lock))
 335
 336 /**
 337  * spin_can_lock - would spin_trylock() succeed?
 338  * @lock: the spinlock in question.
 339  */
 340 #define spin_can_lock(lock)     (!spin_is_locked(lock))
 341
 342 #endif /* __LINUX_SPINLOCK_H */