kernel/spinlock.c

   1 /*
   2  * Copyright (2004) Linus Torvalds
   3  *
   4  * Author: Zwane Mwaikambo <zwane@fsmlabs.com>
   5  *
   6  * Copyright (2004, 2005) Ingo Molnar
   7  *
   8  * This file contains the spinlock/rwlock implementations for the
   9  * SMP and the DEBUG_SPINLOCK cases. (UP-nondebug inlines them)
  10  */
  11
  12 #include <linux/linkage.h>
  13 #include <linux/preempt.h>
  14 #include <linux/spinlock.h>
  15 #include <linux/interrupt.h>
  16 #include <linux/debug_locks.h>
  17 #include <linux/module.h>
  18
  19 /*
  20  * Generic declaration of the raw read_trylock() function,
  21  * architectures are supposed to optimize this:
  22  */
  23 int __lockfunc generic__raw_read_trylock(raw_rwlock_t *lock)
  24 {
  25         __raw_read_lock(lock);
  26         return 1;
  27 }
  28 EXPORT_SYMBOL(generic__raw_read_trylock);
  29
  30 int __lockfunc _spin_trylock(spinlock_t *lock)
  31 {
  32         preempt_disable();
  33         if (_raw_spin_trylock(lock)) {
  34                 spin_acquire(&lock->dep_map, 0, 1, _RET_IP_);
  35                 return 1;
  36         }
  37
  38         preempt_enable();
  39         return 0;
  40 }
  41 EXPORT_SYMBOL(_spin_trylock);
  42
  43 int __lockfunc _read_trylock(rwlock_t *lock)
  44 {
  45         preempt_disable();
  46         if (_raw_read_trylock(lock)) {
  47                 rwlock_acquire_read(&lock->dep_map, 0, 1, _RET_IP_);
  48                 return 1;
  49         }
  50
  51         preempt_enable();
  52         return 0;
  53 }
  54 EXPORT_SYMBOL(_read_trylock);
  55
  56 int __lockfunc _write_trylock(rwlock_t *lock)
  57 {
  58         preempt_disable();
  59         if (_raw_write_trylock(lock)) {
  60                 rwlock_acquire(&lock->dep_map, 0, 1, _RET_IP_);
  61                 return 1;
  62         }
  63
  64         preempt_enable();
  65         return 0;
  66 }
  67 EXPORT_SYMBOL(_write_trylock);
  68
  69 /*
  70  * If lockdep is enabled then we use the non-preemption spin-ops
  71  * even on CONFIG_PREEMPT, because lockdep assumes that interrupts are
  72  * not re-enabled during lock-acquire (which the preempt-spin-ops do):
  73  */
  74 #if !defined(CONFIG_PREEMPT) || !defined(CONFIG_SMP) || \
  75         defined(CONFIG_DEBUG_LOCK_ALLOC)
  76
  77 void __lockfunc _read_lock(rwlock_t *lock)
  78 {
  79         preempt_disable();
  80         rwlock_acquire_read(&lock->dep_map, 0, 0, _RET_IP_);
  81         _raw_read_lock(lock);
  82 }
  83 EXPORT_SYMBOL(_read_lock);
  84
  85 unsigned long __lockfunc _spin_lock_irqsave(spinlock_t *lock)
  86 {
  87         unsigned long flags;
  88
  89         local_irq_save(flags);
  90         preempt_disable();
  91         spin_acquire(&lock->dep_map, 0, 0, _RET_IP_);
  92         /*
  93          * On lockdep we dont want the hand-coded irq-enable of
  94          * _raw_spin_lock_flags() code, because lockdep assumes
  95          * that interrupts are not re-enabled during lock-acquire:
  96          */
  97 #ifdef CONFIG_PROVE_LOCKING
  98         _raw_spin_lock(lock);
  99 #else
 100         _raw_spin_lock_flags(lock, &flags);
 101 #endif
 102         return flags;
 103 }
 104 EXPORT_SYMBOL(_spin_lock_irqsave);
 105
 106 void __lockfunc _spin_lock_irq(spinlock_t *lock)
 107 {
 108         local_irq_disable();
 109         preempt_disable();
 110         spin_acquire(&lock->dep_map, 0, 0, _RET_IP_);
 111         _raw_spin_lock(lock);
 112 }
 113 EXPORT_SYMBOL(_spin_lock_irq);
 114
 115 void __lockfunc _spin_lock_bh(spinlock_t *lock)
 116 {
 117         local_bh_disable();
 118         preempt_disable();
 119         spin_acquire(&lock->dep_map, 0, 0, _RET_IP_);
 120         _raw_spin_lock(lock);
 121 }
 122 EXPORT_SYMBOL(_spin_lock_bh);
 123
 124 unsigned long __lockfunc _read_lock_irqsave(rwlock_t *lock)
 125 {
 126         unsigned long flags;
 127
 128         local_irq_save(flags);
 129         preempt_disable();
 130         rwlock_acquire_read(&lock->dep_map, 0, 0, _RET_IP_);
 131         _raw_read_lock(lock);
 132         return flags;
 133 }
 134 EXPORT_SYMBOL(_read_lock_irqsave);
 135
 136 void __lockfunc _read_lock_irq(rwlock_t *lock)
 137 {
 138         local_irq_disable();
 139         preempt_disable();
 140         rwlock_acquire_read(&lock->dep_map, 0, 0, _RET_IP_);
 141         _raw_read_lock(lock);
 142 }
 143 EXPORT_SYMBOL(_read_lock_irq);
 144
 145 void __lockfunc _read_lock_bh(rwlock_t *lock)
 146 {
 147         local_bh_disable();
 148         preempt_disable();
 149         rwlock_acquire_read(&lock->dep_map, 0, 0, _RET_IP_);
 150         _raw_read_lock(lock);
 151 }
 152 EXPORT_SYMBOL(_read_lock_bh);
 153
 154 unsigned long __lockfunc _write_lock_irqsave(rwlock_t *lock)
 155 {
 156         unsigned long flags;
 157
 158         local_irq_save(flags);
 159         preempt_disable();
 160         rwlock_acquire(&lock->dep_map, 0, 0, _RET_IP_);
 161         _raw_write_lock(lock);
 162         return flags;
 163 }
 164 EXPORT_SYMBOL(_write_lock_irqsave);
 165
 166 void __lockfunc _write_lock_irq(rwlock_t *lock)
 167 {
 168         local_irq_disable();
 169         preempt_disable();
 170         rwlock_acquire(&lock->dep_map, 0, 0, _RET_IP_);
 171         _raw_write_lock(lock);
 172 }
 173 EXPORT_SYMBOL(_write_lock_irq);
 174
 175 void __lockfunc _write_lock_bh(rwlock_t *lock)
 176 {
 177         local_bh_disable();
 178         preempt_disable();
 179         rwlock_acquire(&lock->dep_map, 0, 0, _RET_IP_);
 180         _raw_write_lock(lock);
 181 }
 182 EXPORT_SYMBOL(_write_lock_bh);
 183
 184 void __lockfunc _spin_lock(spinlock_t *lock)
 185 {
 186         preempt_disable();
 187         spin_acquire(&lock->dep_map, 0, 0, _RET_IP_);
 188         _raw_spin_lock(lock);
 189 }
 190
 191 EXPORT_SYMBOL(_spin_lock);
 192
 193 void __lockfunc _write_lock(rwlock_t *lock)
 194 {
 195         preempt_disable();
 196         rwlock_acquire(&lock->dep_map, 0, 0, _RET_IP_);
 197         _raw_write_lock(lock);
 198 }
 199
 200 EXPORT_SYMBOL(_write_lock);
 201
 202 #else /* CONFIG_PREEMPT: */
 203
 204 /*
 205  * This could be a long-held lock. We both prepare to spin for a long
 206  * time (making _this_ CPU preemptable if possible), and we also signal
 207  * towards that other CPU that it should break the lock ASAP.
 208  *
 209  * (We do this in a function because inlining it would be excessive.)
 210  */
 211
 212 #define BUILD_LOCK_OPS(op, locktype)                                    \
 213 void __lockfunc _##op##_lock(locktype##_t *lock)                        \
 214 {                                                                       \
 215         for (;;) {                                                      \
 216                 preempt_disable();                                      \
 217                 if (likely(_raw_##op##_trylock(lock)))                  \
 218                         break;                                          \
 219                 preempt_enable();                                       \
 220                                                                         \
 221                 if (!(lock)->break_lock)                                \
 222                         (lock)->break_lock = 1;                         \
 223                 while (!op##_can_lock(lock) && (lock)->break_lock)      \
 224                         cpu_relax();                                    \
 225         }                                                               \
 226         (lock)->break_lock = 0;                                         \
 227 }                                                                       \
 228                                                                         \
 229 EXPORT_SYMBOL(_##op##_lock);                                            \
 230                                                                         \
 231 unsigned long __lockfunc _##op##_lock_irqsave(locktype##_t *lock)       \
 232 {                                                                       \
 233         unsigned long flags;                                            \
 234                                                                         \
 235         for (;;) {                                                      \
 236                 preempt_disable();                                      \
 237                 local_irq_save(flags);                                  \
 238                 if (likely(_raw_##op##_trylock(lock)))                  \
 239                         break;                                          \
 240                 local_irq_restore(flags);                               \
 241                 preempt_enable();                                       \
 242                                                                         \
 243                 if (!(lock)->break_lock)                                \
 244                         (lock)->break_lock = 1;                         \
 245                 while (!op##_can_lock(lock) && (lock)->break_lock)      \
 246                         cpu_relax();                                    \
 247         }                                                               \
 248         (lock)->break_lock = 0;                                         \
 249         return flags;                                                   \
 250 }                                                                       \
 251                                                                         \
 252 EXPORT_SYMBOL(_##op##_lock_irqsave);                                    \
 253                                                                         \
 254 void __lockfunc _##op##_lock_irq(locktype##_t *lock)                    \
 255 {                                                                       \
 256         _##op##_lock_irqsave(lock);                                     \
 257 }                                                                       \
 258                                                                         \
 259 EXPORT_SYMBOL(_##op##_lock_irq);                                        \
 260                                                                         \
 261 void __lockfunc _##op##_lock_bh(locktype##_t *lock)                     \
 262 {                                                                       \
 263         unsigned long flags;                                            \
 264                                                                         \
 265         /*                                                      */      \
 266         /* Careful: we must exclude softirqs too, hence the     */      \
 267         /* irq-disabling. We use the generic preemption-aware   */      \
 268         /* function:                                            */      \
 269         /**/                                                            \
 270         flags = _##op##_lock_irqsave(lock);                             \
 271         local_bh_disable();                                             \
 272         local_irq_restore(flags);                                       \
 273 }                                                                       \
 274                                                                         \
 275 EXPORT_SYMBOL(_##op##_lock_bh)
 276
 277 /*
 278  * Build preemption-friendly versions of the following
 279  * lock-spinning functions:
 280  *
 281  *         _[spin|read|write]_lock()
 282  *         _[spin|read|write]_lock_irq()
 283  *         _[spin|read|write]_lock_irqsave()
 284  *         _[spin|read|write]_lock_bh()
 285  */
 286 BUILD_LOCK_OPS(spin, spinlock);
 287 BUILD_LOCK_OPS(read, rwlock);
 288 BUILD_LOCK_OPS(write, rwlock);
 289
 290 #endif /* CONFIG_PREEMPT */
 291
 292 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 293
 294 void __lockfunc _spin_lock_nested(spinlock_t *lock, int subclass)
 295 {
 296         preempt_disable();
 297         spin_acquire(&lock->dep_map, subclass, 0, _RET_IP_);
 298         _raw_spin_lock(lock);
 299 }
 300
 301 EXPORT_SYMBOL(_spin_lock_nested);
 302
 303 #endif
 304
 305 void __lockfunc _spin_unlock(spinlock_t *lock)
 306 {
 307         spin_release(&lock->dep_map, 1, _RET_IP_);
 308         _raw_spin_unlock(lock);
 309         preempt_enable();
 310 }
 311 EXPORT_SYMBOL(_spin_unlock);
 312
 313 void __lockfunc _write_unlock(rwlock_t *lock)
 314 {
 315         rwlock_release(&lock->dep_map, 1, _RET_IP_);
 316         _raw_write_unlock(lock);
 317         preempt_enable();
 318 }
 319 EXPORT_SYMBOL(_write_unlock);
 320
 321 void __lockfunc _read_unlock(rwlock_t *lock)
 322 {
 323         rwlock_release(&lock->dep_map, 1, _RET_IP_);
 324         _raw_read_unlock(lock);
 325         preempt_enable();
 326 }
 327 EXPORT_SYMBOL(_read_unlock);
 328
 329 void __lockfunc _spin_unlock_irqrestore(spinlock_t *lock, unsigned long flags)
 330 {
 331         spin_release(&lock->dep_map, 1, _RET_IP_);
 332         _raw_spin_unlock(lock);
 333         local_irq_restore(flags);
 334         preempt_enable();
 335 }
 336 EXPORT_SYMBOL(_spin_unlock_irqrestore);
 337
 338 void __lockfunc _spin_unlock_irq(spinlock_t *lock)
 339 {
 340         spin_release(&lock->dep_map, 1, _RET_IP_);
 341         _raw_spin_unlock(lock);
 342         local_irq_enable();
 343         preempt_enable();
 344 }
 345 EXPORT_SYMBOL(_spin_unlock_irq);
 346
 347 void __lockfunc _spin_unlock_bh(spinlock_t *lock)
 348 {
 349         spin_release(&lock->dep_map, 1, _RET_IP_);
 350         _raw_spin_unlock(lock);
 351         preempt_enable_no_resched();
 352         local_bh_enable_ip((unsigned long)__builtin_return_address(0));
 353 }
 354 EXPORT_SYMBOL(_spin_unlock_bh);
 355
 356 void __lockfunc _read_unlock_irqrestore(rwlock_t *lock, unsigned long flags)
 357 {
 358         rwlock_release(&lock->dep_map, 1, _RET_IP_);
 359         _raw_read_unlock(lock);
 360         local_irq_restore(flags);
 361         preempt_enable();
 362 }
 363 EXPORT_SYMBOL(_read_unlock_irqrestore);
 364
 365 void __lockfunc _read_unlock_irq(rwlock_t *lock)
 366 {
 367         rwlock_release(&lock->dep_map, 1, _RET_IP_);
 368         _raw_read_unlock(lock);
 369         local_irq_enable();
 370         preempt_enable();
 371 }
 372 EXPORT_SYMBOL(_read_unlock_irq);
 373
 374 void __lockfunc _read_unlock_bh(rwlock_t *lock)
 375 {
 376         rwlock_release(&lock->dep_map, 1, _RET_IP_);
 377         _raw_read_unlock(lock);
 378         preempt_enable_no_resched();
 379         local_bh_enable_ip((unsigned long)__builtin_return_address(0));
 380 }
 381 EXPORT_SYMBOL(_read_unlock_bh);
 382
 383 void __lockfunc _write_unlock_irqrestore(rwlock_t *lock, unsigned long flags)
 384 {
 385         rwlock_release(&lock->dep_map, 1, _RET_IP_);
 386         _raw_write_unlock(lock);
 387         local_irq_restore(flags);
 388         preempt_enable();
 389 }
 390 EXPORT_SYMBOL(_write_unlock_irqrestore);
 391
 392 void __lockfunc _write_unlock_irq(rwlock_t *lock)
 393 {
 394         rwlock_release(&lock->dep_map, 1, _RET_IP_);
 395         _raw_write_unlock(lock);
 396         local_irq_enable();
 397         preempt_enable();
 398 }
 399 EXPORT_SYMBOL(_write_unlock_irq);
 400
 401 void __lockfunc _write_unlock_bh(rwlock_t *lock)
 402 {
 403         rwlock_release(&lock->dep_map, 1, _RET_IP_);
 404         _raw_write_unlock(lock);
 405         preempt_enable_no_resched();
 406         local_bh_enable_ip((unsigned long)__builtin_return_address(0));
 407 }
 408 EXPORT_SYMBOL(_write_unlock_bh);
 409
 410 int __lockfunc _spin_trylock_bh(spinlock_t *lock)
 411 {
 412         local_bh_disable();
 413         preempt_disable();
 414         if (_raw_spin_trylock(lock)) {
 415                 spin_acquire(&lock->dep_map, 0, 1, _RET_IP_);
 416                 return 1;
 417         }
 418
 419         preempt_enable_no_resched();
 420         local_bh_enable_ip((unsigned long)__builtin_return_address(0));
 421         return 0;
 422 }
 423 EXPORT_SYMBOL(_spin_trylock_bh);
 424
 425 int in_lock_functions(unsigned long addr)
 426 {
 427         /* Linker adds these: start and end of __lockfunc functions */
 428         extern char __lock_text_start[], __lock_text_end[];
 429
 430         return addr >= (unsigned long)__lock_text_start
 431         && addr < (unsigned long)__lock_text_end;
 432 }
 433 EXPORT_SYMBOL(in_lock_functions);