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  * Note that some architectures have special knowledge about the
  12  * stack frames of these functions in their profile_pc. If you
  13  * change anything significant here that could change the stack
  14  * frame contact the architecture maintainers.
  15  */
  16
  17 #include <linux/linkage.h>
  18 #include <linux/preempt.h>
  19 #include <linux/spinlock.h>
  20 #include <linux/interrupt.h>
  21 #include <linux/debug_locks.h>
  22 #include <linux/module.h>
  23
  24 int __lockfunc _spin_trylock(spinlock_t *lock)
  25 {
  26         preempt_disable();
  27         if (_raw_spin_trylock(lock)) {
  28                 spin_acquire(&lock->dep_map, 0, 1, _RET_IP_);
  29                 return 1;
  30         }
  31
  32         preempt_enable();
  33         return 0;
  34 }
  35 EXPORT_SYMBOL(_spin_trylock);
  36
  37 int __lockfunc _read_trylock(rwlock_t *lock)
  38 {
  39         preempt_disable();
  40         if (_raw_read_trylock(lock)) {
  41                 rwlock_acquire_read(&lock->dep_map, 0, 1, _RET_IP_);
  42                 return 1;
  43         }
  44
  45         preempt_enable();
  46         return 0;
  47 }
  48 EXPORT_SYMBOL(_read_trylock);
  49
  50 int __lockfunc _write_trylock(rwlock_t *lock)
  51 {
  52         preempt_disable();
  53         if (_raw_write_trylock(lock)) {
  54                 rwlock_acquire(&lock->dep_map, 0, 1, _RET_IP_);
  55                 return 1;
  56         }
  57
  58         preempt_enable();
  59         return 0;
  60 }
  61 EXPORT_SYMBOL(_write_trylock);
  62
  63 /*
  64  * If lockdep is enabled then we use the non-preemption spin-ops
  65  * even on CONFIG_PREEMPT, because lockdep assumes that interrupts are
  66  * not re-enabled during lock-acquire (which the preempt-spin-ops do):
  67  */
  68 #if !defined(CONFIG_GENERIC_LOCKBREAK) || defined(CONFIG_DEBUG_LOCK_ALLOC)
  69
  70 void __lockfunc _read_lock(rwlock_t *lock)
  71 {
  72         preempt_disable();
  73         rwlock_acquire_read(&lock->dep_map, 0, 0, _RET_IP_);
  74         LOCK_CONTENDED(lock, _raw_read_trylock, _raw_read_lock);
  75 }
  76 EXPORT_SYMBOL(_read_lock);
  77
  78 unsigned long __lockfunc _spin_lock_irqsave(spinlock_t *lock)
  79 {
  80         unsigned long flags;
  81
  82         local_irq_save(flags);
  83         preempt_disable();
  84         spin_acquire(&lock->dep_map, 0, 0, _RET_IP_);
  85         /*
  86          * On lockdep we dont want the hand-coded irq-enable of
  87          * _raw_spin_lock_flags() code, because lockdep assumes
  88          * that interrupts are not re-enabled during lock-acquire:
  89          */
  90 #ifdef CONFIG_LOCKDEP
  91         LOCK_CONTENDED(lock, _raw_spin_trylock, _raw_spin_lock);
  92 #else
  93         _raw_spin_lock_flags(lock, &flags);
  94 #endif
  95         return flags;
  96 }
  97 EXPORT_SYMBOL(_spin_lock_irqsave);
  98
  99 void __lockfunc _spin_lock_irq(spinlock_t *lock)
 100 {
 101         local_irq_disable();
 102         preempt_disable();
 103         spin_acquire(&lock->dep_map, 0, 0, _RET_IP_);
 104         LOCK_CONTENDED(lock, _raw_spin_trylock, _raw_spin_lock);
 105 }
 106 EXPORT_SYMBOL(_spin_lock_irq);
 107
 108 void __lockfunc _spin_lock_bh(spinlock_t *lock)
 109 {
 110         local_bh_disable();
 111         preempt_disable();
 112         spin_acquire(&lock->dep_map, 0, 0, _RET_IP_);
 113         LOCK_CONTENDED(lock, _raw_spin_trylock, _raw_spin_lock);
 114 }
 115 EXPORT_SYMBOL(_spin_lock_bh);
 116
 117 unsigned long __lockfunc _read_lock_irqsave(rwlock_t *lock)
 118 {
 119         unsigned long flags;
 120
 121         local_irq_save(flags);
 122         preempt_disable();
 123         rwlock_acquire_read(&lock->dep_map, 0, 0, _RET_IP_);
 124         LOCK_CONTENDED(lock, _raw_read_trylock, _raw_read_lock);
 125         return flags;
 126 }
 127 EXPORT_SYMBOL(_read_lock_irqsave);
 128
 129 void __lockfunc _read_lock_irq(rwlock_t *lock)
 130 {
 131         local_irq_disable();
 132         preempt_disable();
 133         rwlock_acquire_read(&lock->dep_map, 0, 0, _RET_IP_);
 134         LOCK_CONTENDED(lock, _raw_read_trylock, _raw_read_lock);
 135 }
 136 EXPORT_SYMBOL(_read_lock_irq);
 137
 138 void __lockfunc _read_lock_bh(rwlock_t *lock)
 139 {
 140         local_bh_disable();
 141         preempt_disable();
 142         rwlock_acquire_read(&lock->dep_map, 0, 0, _RET_IP_);
 143         LOCK_CONTENDED(lock, _raw_read_trylock, _raw_read_lock);
 144 }
 145 EXPORT_SYMBOL(_read_lock_bh);
 146
 147 unsigned long __lockfunc _write_lock_irqsave(rwlock_t *lock)
 148 {
 149         unsigned long flags;
 150
 151         local_irq_save(flags);
 152         preempt_disable();
 153         rwlock_acquire(&lock->dep_map, 0, 0, _RET_IP_);
 154         LOCK_CONTENDED(lock, _raw_write_trylock, _raw_write_lock);
 155         return flags;
 156 }
 157 EXPORT_SYMBOL(_write_lock_irqsave);
 158
 159 void __lockfunc _write_lock_irq(rwlock_t *lock)
 160 {
 161         local_irq_disable();
 162         preempt_disable();
 163         rwlock_acquire(&lock->dep_map, 0, 0, _RET_IP_);
 164         LOCK_CONTENDED(lock, _raw_write_trylock, _raw_write_lock);
 165 }
 166 EXPORT_SYMBOL(_write_lock_irq);
 167
 168 void __lockfunc _write_lock_bh(rwlock_t *lock)
 169 {
 170         local_bh_disable();
 171         preempt_disable();
 172         rwlock_acquire(&lock->dep_map, 0, 0, _RET_IP_);
 173         LOCK_CONTENDED(lock, _raw_write_trylock, _raw_write_lock);
 174 }
 175 EXPORT_SYMBOL(_write_lock_bh);
 176
 177 void __lockfunc _spin_lock(spinlock_t *lock)
 178 {
 179         preempt_disable();
 180         spin_acquire(&lock->dep_map, 0, 0, _RET_IP_);
 181         LOCK_CONTENDED(lock, _raw_spin_trylock, _raw_spin_lock);
 182 }
 183
 184 EXPORT_SYMBOL(_spin_lock);
 185
 186 void __lockfunc _write_lock(rwlock_t *lock)
 187 {
 188         preempt_disable();
 189         rwlock_acquire(&lock->dep_map, 0, 0, _RET_IP_);
 190         LOCK_CONTENDED(lock, _raw_write_trylock, _raw_write_lock);
 191 }
 192
 193 EXPORT_SYMBOL(_write_lock);
 194
 195 #else /* CONFIG_PREEMPT: */
 196
 197 /*
 198  * This could be a long-held lock. We both prepare to spin for a long
 199  * time (making _this_ CPU preemptable if possible), and we also signal
 200  * towards that other CPU that it should break the lock ASAP.
 201  *
 202  * (We do this in a function because inlining it would be excessive.)
 203  */
 204
 205 #define BUILD_LOCK_OPS(op, locktype)                                    \
 206 void __lockfunc _##op##_lock(locktype##_t *lock)                        \
 207 {                                                                       \
 208         for (;;) {                                                      \
 209                 preempt_disable();                                      \
 210                 if (likely(_raw_##op##_trylock(lock)))                  \
 211                         break;                                          \
 212                 preempt_enable();                                       \
 213                                                                         \
 214                 if (!(lock)->break_lock)                                \
 215                         (lock)->break_lock = 1;                         \
 216                 while (!op##_can_lock(lock) && (lock)->break_lock)      \
 217                         _raw_##op##_relax(&lock->raw_lock);             \
 218         }                                                               \
 219         (lock)->break_lock = 0;                                         \
 220 }                                                                       \
 221                                                                         \
 222 EXPORT_SYMBOL(_##op##_lock);                                            \
 223                                                                         \
 224 unsigned long __lockfunc _##op##_lock_irqsave(locktype##_t *lock)       \
 225 {                                                                       \
 226         unsigned long flags;                                            \
 227                                                                         \
 228         for (;;) {                                                      \
 229                 preempt_disable();                                      \
 230                 local_irq_save(flags);                                  \
 231                 if (likely(_raw_##op##_trylock(lock)))                  \
 232                         break;                                          \
 233                 local_irq_restore(flags);                               \
 234                 preempt_enable();                                       \
 235                                                                         \
 236                 if (!(lock)->break_lock)                                \
 237                         (lock)->break_lock = 1;                         \
 238                 while (!op##_can_lock(lock) && (lock)->break_lock)      \
 239                         _raw_##op##_relax(&lock->raw_lock);             \
 240         }                                                               \
 241         (lock)->break_lock = 0;                                         \
 242         return flags;                                                   \
 243 }                                                                       \
 244                                                                         \
 245 EXPORT_SYMBOL(_##op##_lock_irqsave);                                    \
 246                                                                         \
 247 void __lockfunc _##op##_lock_irq(locktype##_t *lock)                    \
 248 {                                                                       \
 249         _##op##_lock_irqsave(lock);                                     \
 250 }                                                                       \
 251                                                                         \
 252 EXPORT_SYMBOL(_##op##_lock_irq);                                        \
 253                                                                         \
 254 void __lockfunc _##op##_lock_bh(locktype##_t *lock)                     \
 255 {                                                                       \
 256         unsigned long flags;                                            \
 257                                                                         \
 258         /*                                                      */      \
 259         /* Careful: we must exclude softirqs too, hence the     */      \
 260         /* irq-disabling. We use the generic preemption-aware   */      \
 261         /* function:                                            */      \
 262         /**/                                                            \
 263         flags = _##op##_lock_irqsave(lock);                             \
 264         local_bh_disable();                                             \
 265         local_irq_restore(flags);                                       \
 266 }                                                                       \
 267                                                                         \
 268 EXPORT_SYMBOL(_##op##_lock_bh)
 269
 270 /*
 271  * Build preemption-friendly versions of the following
 272  * lock-spinning functions:
 273  *
 274  *         _[spin|read|write]_lock()
 275  *         _[spin|read|write]_lock_irq()
 276  *         _[spin|read|write]_lock_irqsave()
 277  *         _[spin|read|write]_lock_bh()
 278  */
 279 BUILD_LOCK_OPS(spin, spinlock);
 280 BUILD_LOCK_OPS(read, rwlock);
 281 BUILD_LOCK_OPS(write, rwlock);
 282
 283 #endif /* CONFIG_PREEMPT */
 284
 285 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 286
 287 void __lockfunc _spin_lock_nested(spinlock_t *lock, int subclass)
 288 {
 289         preempt_disable();
 290         spin_acquire(&lock->dep_map, subclass, 0, _RET_IP_);
 291         LOCK_CONTENDED(lock, _raw_spin_trylock, _raw_spin_lock);
 292 }
 293
 294 EXPORT_SYMBOL(_spin_lock_nested);
 295 unsigned long __lockfunc _spin_lock_irqsave_nested(spinlock_t *lock, int subclass)
 296 {
 297         unsigned long flags;
 298
 299         local_irq_save(flags);
 300         preempt_disable();
 301         spin_acquire(&lock->dep_map, subclass, 0, _RET_IP_);
 302         /*
 303          * On lockdep we dont want the hand-coded irq-enable of
 304          * _raw_spin_lock_flags() code, because lockdep assumes
 305          * that interrupts are not re-enabled during lock-acquire:
 306          */
 307 #ifdef CONFIG_LOCKDEP
 308         LOCK_CONTENDED(lock, _raw_spin_trylock, _raw_spin_lock);
 309 #else
 310         _raw_spin_lock_flags(lock, &flags);
 311 #endif
 312         return flags;
 313 }
 314
 315 EXPORT_SYMBOL(_spin_lock_irqsave_nested);
 316
 317 #endif
 318
 319 void __lockfunc _spin_unlock(spinlock_t *lock)
 320 {
 321         spin_release(&lock->dep_map, 1, _RET_IP_);
 322         _raw_spin_unlock(lock);
 323         preempt_enable();
 324 }
 325 EXPORT_SYMBOL(_spin_unlock);
 326
 327 void __lockfunc _write_unlock(rwlock_t *lock)
 328 {
 329         rwlock_release(&lock->dep_map, 1, _RET_IP_);
 330         _raw_write_unlock(lock);
 331         preempt_enable();
 332 }
 333 EXPORT_SYMBOL(_write_unlock);
 334
 335 void __lockfunc _read_unlock(rwlock_t *lock)
 336 {
 337         rwlock_release(&lock->dep_map, 1, _RET_IP_);
 338         _raw_read_unlock(lock);
 339         preempt_enable();
 340 }
 341 EXPORT_SYMBOL(_read_unlock);
 342
 343 void __lockfunc _spin_unlock_irqrestore(spinlock_t *lock, unsigned long flags)
 344 {
 345         spin_release(&lock->dep_map, 1, _RET_IP_);
 346         _raw_spin_unlock(lock);
 347         local_irq_restore(flags);
 348         preempt_enable();
 349 }
 350 EXPORT_SYMBOL(_spin_unlock_irqrestore);
 351
 352 void __lockfunc _spin_unlock_irq(spinlock_t *lock)
 353 {
 354         spin_release(&lock->dep_map, 1, _RET_IP_);
 355         _raw_spin_unlock(lock);
 356         local_irq_enable();
 357         preempt_enable();
 358 }
 359 EXPORT_SYMBOL(_spin_unlock_irq);
 360
 361 void __lockfunc _spin_unlock_bh(spinlock_t *lock)
 362 {
 363         spin_release(&lock->dep_map, 1, _RET_IP_);
 364         _raw_spin_unlock(lock);
 365         preempt_enable_no_resched();
 366         local_bh_enable_ip((unsigned long)__builtin_return_address(0));
 367 }
 368 EXPORT_SYMBOL(_spin_unlock_bh);
 369
 370 void __lockfunc _read_unlock_irqrestore(rwlock_t *lock, unsigned long flags)
 371 {
 372         rwlock_release(&lock->dep_map, 1, _RET_IP_);
 373         _raw_read_unlock(lock);
 374         local_irq_restore(flags);
 375         preempt_enable();
 376 }
 377 EXPORT_SYMBOL(_read_unlock_irqrestore);
 378
 379 void __lockfunc _read_unlock_irq(rwlock_t *lock)
 380 {
 381         rwlock_release(&lock->dep_map, 1, _RET_IP_);
 382         _raw_read_unlock(lock);
 383         local_irq_enable();
 384         preempt_enable();
 385 }
 386 EXPORT_SYMBOL(_read_unlock_irq);
 387
 388 void __lockfunc _read_unlock_bh(rwlock_t *lock)
 389 {
 390         rwlock_release(&lock->dep_map, 1, _RET_IP_);
 391         _raw_read_unlock(lock);
 392         preempt_enable_no_resched();
 393         local_bh_enable_ip((unsigned long)__builtin_return_address(0));
 394 }
 395 EXPORT_SYMBOL(_read_unlock_bh);
 396
 397 void __lockfunc _write_unlock_irqrestore(rwlock_t *lock, unsigned long flags)
 398 {
 399         rwlock_release(&lock->dep_map, 1, _RET_IP_);
 400         _raw_write_unlock(lock);
 401         local_irq_restore(flags);
 402         preempt_enable();
 403 }
 404 EXPORT_SYMBOL(_write_unlock_irqrestore);
 405
 406 void __lockfunc _write_unlock_irq(rwlock_t *lock)
 407 {
 408         rwlock_release(&lock->dep_map, 1, _RET_IP_);
 409         _raw_write_unlock(lock);
 410         local_irq_enable();
 411         preempt_enable();
 412 }
 413 EXPORT_SYMBOL(_write_unlock_irq);
 414
 415 void __lockfunc _write_unlock_bh(rwlock_t *lock)
 416 {
 417         rwlock_release(&lock->dep_map, 1, _RET_IP_);
 418         _raw_write_unlock(lock);
 419         preempt_enable_no_resched();
 420         local_bh_enable_ip((unsigned long)__builtin_return_address(0));
 421 }
 422 EXPORT_SYMBOL(_write_unlock_bh);
 423
 424 int __lockfunc _spin_trylock_bh(spinlock_t *lock)
 425 {
 426         local_bh_disable();
 427         preempt_disable();
 428         if (_raw_spin_trylock(lock)) {
 429                 spin_acquire(&lock->dep_map, 0, 1, _RET_IP_);
 430                 return 1;
 431         }
 432
 433         preempt_enable_no_resched();
 434         local_bh_enable_ip((unsigned long)__builtin_return_address(0));
 435         return 0;
 436 }
 437 EXPORT_SYMBOL(_spin_trylock_bh);
 438
 439 int in_lock_functions(unsigned long addr)
 440 {
 441         /* Linker adds these: start and end of __lockfunc functions */
 442         extern char __lock_text_start[], __lock_text_end[];
 443
 444         return addr >= (unsigned long)__lock_text_start
 445         && addr < (unsigned long)__lock_text_end;
 446 }
 447 EXPORT_SYMBOL(in_lock_functions);