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/export.h>
  23
  24 /*
  25  * If lockdep is enabled then we use the non-preemption spin-ops
  26  * even on CONFIG_PREEMPT, because lockdep assumes that interrupts are
  27  * not re-enabled during lock-acquire (which the preempt-spin-ops do):
  28  */
  29 #if !defined(CONFIG_GENERIC_LOCKBREAK) || defined(CONFIG_DEBUG_LOCK_ALLOC)
  30 /*
  31  * The __lock_function inlines are taken from
  32  * include/linux/spinlock_api_smp.h
  33  */
  34 #else
  35 #define raw_read_can_lock(l)    read_can_lock(l)
  36 #define raw_write_can_lock(l)   write_can_lock(l)
  37
  38 /*
  39  * Some architectures can relax in favour of the CPU owning the lock.
  40  */
  41 #ifndef arch_read_relax
  42 # define arch_read_relax(l)     cpu_relax()
  43 #endif
  44 #ifndef arch_write_relax
  45 # define arch_write_relax(l)    cpu_relax()
  46 #endif
  47 #ifndef arch_spin_relax
  48 # define arch_spin_relax(l)     cpu_relax()
  49 #endif
  50
  51 /*
  52  * We build the __lock_function inlines here. They are too large for
  53  * inlining all over the place, but here is only one user per function
  54  * which embedds them into the calling _lock_function below.
  55  *
  56  * This could be a long-held lock. We both prepare to spin for a long
  57  * time (making _this_ CPU preemptable if possible), and we also signal
  58  * towards that other CPU that it should break the lock ASAP.
  59  */
  60 #define BUILD_LOCK_OPS(op, locktype)                                    \
  61 void __lockfunc __raw_##op##_lock(locktype##_t *lock)                   \
  62 {                                                                       \
  63         for (;;) {                                                      \
  64                 preempt_disable();                                      \
  65                 if (likely(do_raw_##op##_trylock(lock)))                \
  66                         break;                                          \
  67                 preempt_enable();                                       \
  68                                                                         \
  69                 if (!(lock)->break_lock)                                \
  70                         (lock)->break_lock = 1;                         \
  71                 while (!raw_##op##_can_lock(lock) && (lock)->break_lock)\
  72                         arch_##op##_relax(&lock->raw_lock);             \
  73         }                                                               \
  74         (lock)->break_lock = 0;                                         \
  75 }                                                                       \
  76                                                                         \
  77 unsigned long __lockfunc __raw_##op##_lock_irqsave(locktype##_t *lock)  \
  78 {                                                                       \
  79         unsigned long flags;                                            \
  80                                                                         \
  81         for (;;) {                                                      \
  82                 preempt_disable();                                      \
  83                 local_irq_save(flags);                                  \
  84                 if (likely(do_raw_##op##_trylock(lock)))                \
  85                         break;                                          \
  86                 local_irq_restore(flags);                               \
  87                 preempt_enable();                                       \
  88                                                                         \
  89                 if (!(lock)->break_lock)                                \
  90                         (lock)->break_lock = 1;                         \
  91                 while (!raw_##op##_can_lock(lock) && (lock)->break_lock)\
  92                         arch_##op##_relax(&lock->raw_lock);             \
  93         }                                                               \
  94         (lock)->break_lock = 0;                                         \
  95         return flags;                                                   \
  96 }                                                                       \
  97                                                                         \
  98 void __lockfunc __raw_##op##_lock_irq(locktype##_t *lock)               \
  99 {                                                                       \
 100         _raw_##op##_lock_irqsave(lock);                                 \
 101 }                                                                       \
 102                                                                         \
 103 void __lockfunc __raw_##op##_lock_bh(locktype##_t *lock)                \
 104 {                                                                       \
 105         unsigned long flags;                                            \
 106                                                                         \
 107         /*                                                      */      \
 108         /* Careful: we must exclude softirqs too, hence the     */      \
 109         /* irq-disabling. We use the generic preemption-aware   */      \
 110         /* function:                                            */      \
 111         /**/                                                            \
 112         flags = _raw_##op##_lock_irqsave(lock);                         \
 113         local_bh_disable();                                             \
 114         local_irq_restore(flags);                                       \
 115 }                                                                       \
 116
 117 /*
 118  * Build preemption-friendly versions of the following
 119  * lock-spinning functions:
 120  *
 121  *         __[spin|read|write]_lock()
 122  *         __[spin|read|write]_lock_irq()
 123  *         __[spin|read|write]_lock_irqsave()
 124  *         __[spin|read|write]_lock_bh()
 125  */
 126 BUILD_LOCK_OPS(spin, raw_spinlock);
 127 BUILD_LOCK_OPS(read, rwlock);
 128 BUILD_LOCK_OPS(write, rwlock);
 129
 130 #endif
 131
 132 #ifndef CONFIG_INLINE_SPIN_TRYLOCK
 133 int __lockfunc _raw_spin_trylock(raw_spinlock_t *lock)
 134 {
 135         return __raw_spin_trylock(lock);
 136 }
 137 EXPORT_SYMBOL(_raw_spin_trylock);
 138 #endif
 139
 140 #ifndef CONFIG_INLINE_SPIN_TRYLOCK_BH
 141 int __lockfunc _raw_spin_trylock_bh(raw_spinlock_t *lock)
 142 {
 143         return __raw_spin_trylock_bh(lock);
 144 }
 145 EXPORT_SYMBOL(_raw_spin_trylock_bh);
 146 #endif
 147
 148 #ifndef CONFIG_INLINE_SPIN_LOCK
 149 void __lockfunc _raw_spin_lock(raw_spinlock_t *lock)
 150 {
 151         __raw_spin_lock(lock);
 152 }
 153 EXPORT_SYMBOL(_raw_spin_lock);
 154 #endif
 155
 156 #ifndef CONFIG_INLINE_SPIN_LOCK_IRQSAVE
 157 unsigned long __lockfunc _raw_spin_lock_irqsave(raw_spinlock_t *lock)
 158 {
 159         return __raw_spin_lock_irqsave(lock);
 160 }
 161 EXPORT_SYMBOL(_raw_spin_lock_irqsave);
 162 #endif
 163
 164 #ifndef CONFIG_INLINE_SPIN_LOCK_IRQ
 165 void __lockfunc _raw_spin_lock_irq(raw_spinlock_t *lock)
 166 {
 167         __raw_spin_lock_irq(lock);
 168 }
 169 EXPORT_SYMBOL(_raw_spin_lock_irq);
 170 #endif
 171
 172 #ifndef CONFIG_INLINE_SPIN_LOCK_BH
 173 void __lockfunc _raw_spin_lock_bh(raw_spinlock_t *lock)
 174 {
 175         __raw_spin_lock_bh(lock);
 176 }
 177 EXPORT_SYMBOL(_raw_spin_lock_bh);
 178 #endif
 179
 180 #ifdef CONFIG_UNINLINE_SPIN_UNLOCK
 181 void __lockfunc _raw_spin_unlock(raw_spinlock_t *lock)
 182 {
 183         __raw_spin_unlock(lock);
 184 }
 185 EXPORT_SYMBOL(_raw_spin_unlock);
 186 #endif
 187
 188 #ifndef CONFIG_INLINE_SPIN_UNLOCK_IRQRESTORE
 189 void __lockfunc _raw_spin_unlock_irqrestore(raw_spinlock_t *lock, unsigned long flags)
 190 {
 191         __raw_spin_unlock_irqrestore(lock, flags);
 192 }
 193 EXPORT_SYMBOL(_raw_spin_unlock_irqrestore);
 194 #endif
 195
 196 #ifndef CONFIG_INLINE_SPIN_UNLOCK_IRQ
 197 void __lockfunc _raw_spin_unlock_irq(raw_spinlock_t *lock)
 198 {
 199         __raw_spin_unlock_irq(lock);
 200 }
 201 EXPORT_SYMBOL(_raw_spin_unlock_irq);
 202 #endif
 203
 204 #ifndef CONFIG_INLINE_SPIN_UNLOCK_BH
 205 void __lockfunc _raw_spin_unlock_bh(raw_spinlock_t *lock)
 206 {
 207         __raw_spin_unlock_bh(lock);
 208 }
 209 EXPORT_SYMBOL(_raw_spin_unlock_bh);
 210 #endif
 211
 212 #ifndef CONFIG_INLINE_READ_TRYLOCK
 213 int __lockfunc _raw_read_trylock(rwlock_t *lock)
 214 {
 215         return __raw_read_trylock(lock);
 216 }
 217 EXPORT_SYMBOL(_raw_read_trylock);
 218 #endif
 219
 220 #ifndef CONFIG_INLINE_READ_LOCK
 221 void __lockfunc _raw_read_lock(rwlock_t *lock)
 222 {
 223         __raw_read_lock(lock);
 224 }
 225 EXPORT_SYMBOL(_raw_read_lock);
 226 #endif
 227
 228 #ifndef CONFIG_INLINE_READ_LOCK_IRQSAVE
 229 unsigned long __lockfunc _raw_read_lock_irqsave(rwlock_t *lock)
 230 {
 231         return __raw_read_lock_irqsave(lock);
 232 }
 233 EXPORT_SYMBOL(_raw_read_lock_irqsave);
 234 #endif
 235
 236 #ifndef CONFIG_INLINE_READ_LOCK_IRQ
 237 void __lockfunc _raw_read_lock_irq(rwlock_t *lock)
 238 {
 239         __raw_read_lock_irq(lock);
 240 }
 241 EXPORT_SYMBOL(_raw_read_lock_irq);
 242 #endif
 243
 244 #ifndef CONFIG_INLINE_READ_LOCK_BH
 245 void __lockfunc _raw_read_lock_bh(rwlock_t *lock)
 246 {
 247         __raw_read_lock_bh(lock);
 248 }
 249 EXPORT_SYMBOL(_raw_read_lock_bh);
 250 #endif
 251
 252 #ifndef CONFIG_INLINE_READ_UNLOCK
 253 void __lockfunc _raw_read_unlock(rwlock_t *lock)
 254 {
 255         __raw_read_unlock(lock);
 256 }
 257 EXPORT_SYMBOL(_raw_read_unlock);
 258 #endif
 259
 260 #ifndef CONFIG_INLINE_READ_UNLOCK_IRQRESTORE
 261 void __lockfunc _raw_read_unlock_irqrestore(rwlock_t *lock, unsigned long flags)
 262 {
 263         __raw_read_unlock_irqrestore(lock, flags);
 264 }
 265 EXPORT_SYMBOL(_raw_read_unlock_irqrestore);
 266 #endif
 267
 268 #ifndef CONFIG_INLINE_READ_UNLOCK_IRQ
 269 void __lockfunc _raw_read_unlock_irq(rwlock_t *lock)
 270 {
 271         __raw_read_unlock_irq(lock);
 272 }
 273 EXPORT_SYMBOL(_raw_read_unlock_irq);
 274 #endif
 275
 276 #ifndef CONFIG_INLINE_READ_UNLOCK_BH
 277 void __lockfunc _raw_read_unlock_bh(rwlock_t *lock)
 278 {
 279         __raw_read_unlock_bh(lock);
 280 }
 281 EXPORT_SYMBOL(_raw_read_unlock_bh);
 282 #endif
 283
 284 #ifndef CONFIG_INLINE_WRITE_TRYLOCK
 285 int __lockfunc _raw_write_trylock(rwlock_t *lock)
 286 {
 287         return __raw_write_trylock(lock);
 288 }
 289 EXPORT_SYMBOL(_raw_write_trylock);
 290 #endif
 291
 292 #ifndef CONFIG_INLINE_WRITE_LOCK
 293 void __lockfunc _raw_write_lock(rwlock_t *lock)
 294 {
 295         __raw_write_lock(lock);
 296 }
 297 EXPORT_SYMBOL(_raw_write_lock);
 298 #endif
 299
 300 #ifndef CONFIG_INLINE_WRITE_LOCK_IRQSAVE
 301 unsigned long __lockfunc _raw_write_lock_irqsave(rwlock_t *lock)
 302 {
 303         return __raw_write_lock_irqsave(lock);
 304 }
 305 EXPORT_SYMBOL(_raw_write_lock_irqsave);
 306 #endif
 307
 308 #ifndef CONFIG_INLINE_WRITE_LOCK_IRQ
 309 void __lockfunc _raw_write_lock_irq(rwlock_t *lock)
 310 {
 311         __raw_write_lock_irq(lock);
 312 }
 313 EXPORT_SYMBOL(_raw_write_lock_irq);
 314 #endif
 315
 316 #ifndef CONFIG_INLINE_WRITE_LOCK_BH
 317 void __lockfunc _raw_write_lock_bh(rwlock_t *lock)
 318 {
 319         __raw_write_lock_bh(lock);
 320 }
 321 EXPORT_SYMBOL(_raw_write_lock_bh);
 322 #endif
 323
 324 #ifndef CONFIG_INLINE_WRITE_UNLOCK
 325 void __lockfunc _raw_write_unlock(rwlock_t *lock)
 326 {
 327         __raw_write_unlock(lock);
 328 }
 329 EXPORT_SYMBOL(_raw_write_unlock);
 330 #endif
 331
 332 #ifndef CONFIG_INLINE_WRITE_UNLOCK_IRQRESTORE
 333 void __lockfunc _raw_write_unlock_irqrestore(rwlock_t *lock, unsigned long flags)
 334 {
 335         __raw_write_unlock_irqrestore(lock, flags);
 336 }
 337 EXPORT_SYMBOL(_raw_write_unlock_irqrestore);
 338 #endif
 339
 340 #ifndef CONFIG_INLINE_WRITE_UNLOCK_IRQ
 341 void __lockfunc _raw_write_unlock_irq(rwlock_t *lock)
 342 {
 343         __raw_write_unlock_irq(lock);
 344 }
 345 EXPORT_SYMBOL(_raw_write_unlock_irq);
 346 #endif
 347
 348 #ifndef CONFIG_INLINE_WRITE_UNLOCK_BH
 349 void __lockfunc _raw_write_unlock_bh(rwlock_t *lock)
 350 {
 351         __raw_write_unlock_bh(lock);
 352 }
 353 EXPORT_SYMBOL(_raw_write_unlock_bh);
 354 #endif
 355
 356 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 357
 358 void __lockfunc _raw_spin_lock_nested(raw_spinlock_t *lock, int subclass)
 359 {
 360         preempt_disable();
 361         spin_acquire(&lock->dep_map, subclass, 0, _RET_IP_);
 362         LOCK_CONTENDED(lock, do_raw_spin_trylock, do_raw_spin_lock);
 363 }
 364 EXPORT_SYMBOL(_raw_spin_lock_nested);
 365
 366 unsigned long __lockfunc _raw_spin_lock_irqsave_nested(raw_spinlock_t *lock,
 367                                                    int subclass)
 368 {
 369         unsigned long flags;
 370
 371         local_irq_save(flags);
 372         preempt_disable();
 373         spin_acquire(&lock->dep_map, subclass, 0, _RET_IP_);
 374         LOCK_CONTENDED_FLAGS(lock, do_raw_spin_trylock, do_raw_spin_lock,
 375                                 do_raw_spin_lock_flags, &flags);
 376         return flags;
 377 }
 378 EXPORT_SYMBOL(_raw_spin_lock_irqsave_nested);
 379
 380 void __lockfunc _raw_spin_lock_nest_lock(raw_spinlock_t *lock,
 381                                      struct lockdep_map *nest_lock)
 382 {
 383         preempt_disable();
 384         spin_acquire_nest(&lock->dep_map, 0, 0, nest_lock, _RET_IP_);
 385         LOCK_CONTENDED(lock, do_raw_spin_trylock, do_raw_spin_lock);
 386 }
 387 EXPORT_SYMBOL(_raw_spin_lock_nest_lock);
 388
 389 #endif
 390
 391 notrace int in_lock_functions(unsigned long addr)
 392 {
 393         /* Linker adds these: start and end of __lockfunc functions */
 394         extern char __lock_text_start[], __lock_text_end[];
 395
 396         return addr >= (unsigned long)__lock_text_start
 397         && addr < (unsigned long)__lock_text_end;
 398 }
 399 EXPORT_SYMBOL(in_lock_functions);