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