linux/kernel/spinlock.c
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   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)                                    \
  47void __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                                                                        \
  63unsigned 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                                                                        \
  84void __lockfunc __raw_##op##_lock_irq(locktype##_t *lock)               \
  85{                                                                       \
  86        _raw_##op##_lock_irqsave(lock);                                 \
  87}                                                                       \
  88                                                                        \
  89void __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 */
 112BUILD_LOCK_OPS(spin, raw_spinlock);
 113BUILD_LOCK_OPS(read, rwlock);
 114BUILD_LOCK_OPS(write, rwlock);
 115
 116#endif
 117
 118#ifndef CONFIG_INLINE_SPIN_TRYLOCK
 119int __lockfunc _raw_spin_trylock(raw_spinlock_t *lock)
 120{
 121        return __raw_spin_trylock(lock);
 122}
 123EXPORT_SYMBOL(_raw_spin_trylock);
 124#endif
 125
 126#ifndef CONFIG_INLINE_SPIN_TRYLOCK_BH
 127int __lockfunc _raw_spin_trylock_bh(raw_spinlock_t *lock)
 128{
 129        return __raw_spin_trylock_bh(lock);
 130}
 131EXPORT_SYMBOL(_raw_spin_trylock_bh);
 132#endif
 133
 134#ifndef CONFIG_INLINE_SPIN_LOCK
 135void __lockfunc _raw_spin_lock(raw_spinlock_t *lock)
 136{
 137        __raw_spin_lock(lock);
 138}
 139EXPORT_SYMBOL(_raw_spin_lock);
 140#endif
 141
 142#ifndef CONFIG_INLINE_SPIN_LOCK_IRQSAVE
 143unsigned long __lockfunc _raw_spin_lock_irqsave(raw_spinlock_t *lock)
 144{
 145        return __raw_spin_lock_irqsave(lock);
 146}
 147EXPORT_SYMBOL(_raw_spin_lock_irqsave);
 148#endif
 149
 150#ifndef CONFIG_INLINE_SPIN_LOCK_IRQ
 151void __lockfunc _raw_spin_lock_irq(raw_spinlock_t *lock)
 152{
 153        __raw_spin_lock_irq(lock);
 154}
 155EXPORT_SYMBOL(_raw_spin_lock_irq);
 156#endif
 157
 158#ifndef CONFIG_INLINE_SPIN_LOCK_BH
 159void __lockfunc _raw_spin_lock_bh(raw_spinlock_t *lock)
 160{
 161        __raw_spin_lock_bh(lock);
 162}
 163EXPORT_SYMBOL(_raw_spin_lock_bh);
 164#endif
 165
 166#ifdef CONFIG_UNINLINE_SPIN_UNLOCK
 167void __lockfunc _raw_spin_unlock(raw_spinlock_t *lock)
 168{
 169        __raw_spin_unlock(lock);
 170}
 171EXPORT_SYMBOL(_raw_spin_unlock);
 172#endif
 173
 174#ifndef CONFIG_INLINE_SPIN_UNLOCK_IRQRESTORE
 175void __lockfunc _raw_spin_unlock_irqrestore(raw_spinlock_t *lock, unsigned long flags)
 176{
 177        __raw_spin_unlock_irqrestore(lock, flags);
 178}
 179EXPORT_SYMBOL(_raw_spin_unlock_irqrestore);
 180#endif
 181
 182#ifndef CONFIG_INLINE_SPIN_UNLOCK_IRQ
 183void __lockfunc _raw_spin_unlock_irq(raw_spinlock_t *lock)
 184{
 185        __raw_spin_unlock_irq(lock);
 186}
 187EXPORT_SYMBOL(_raw_spin_unlock_irq);
 188#endif
 189
 190#ifndef CONFIG_INLINE_SPIN_UNLOCK_BH
 191void __lockfunc _raw_spin_unlock_bh(raw_spinlock_t *lock)
 192{
 193        __raw_spin_unlock_bh(lock);
 194}
 195EXPORT_SYMBOL(_raw_spin_unlock_bh);
 196#endif
 197
 198#ifndef CONFIG_INLINE_READ_TRYLOCK
 199int __lockfunc _raw_read_trylock(rwlock_t *lock)
 200{
 201        return __raw_read_trylock(lock);
 202}
 203EXPORT_SYMBOL(_raw_read_trylock);
 204#endif
 205
 206#ifndef CONFIG_INLINE_READ_LOCK
 207void __lockfunc _raw_read_lock(rwlock_t *lock)
 208{
 209        __raw_read_lock(lock);
 210}
 211EXPORT_SYMBOL(_raw_read_lock);
 212#endif
 213
 214#ifndef CONFIG_INLINE_READ_LOCK_IRQSAVE
 215unsigned long __lockfunc _raw_read_lock_irqsave(rwlock_t *lock)
 216{
 217        return __raw_read_lock_irqsave(lock);
 218}
 219EXPORT_SYMBOL(_raw_read_lock_irqsave);
 220#endif
 221
 222#ifndef CONFIG_INLINE_READ_LOCK_IRQ
 223void __lockfunc _raw_read_lock_irq(rwlock_t *lock)
 224{
 225        __raw_read_lock_irq(lock);
 226}
 227EXPORT_SYMBOL(_raw_read_lock_irq);
 228#endif
 229
 230#ifndef CONFIG_INLINE_READ_LOCK_BH
 231void __lockfunc _raw_read_lock_bh(rwlock_t *lock)
 232{
 233        __raw_read_lock_bh(lock);
 234}
 235EXPORT_SYMBOL(_raw_read_lock_bh);
 236#endif
 237
 238#ifndef CONFIG_INLINE_READ_UNLOCK
 239void __lockfunc _raw_read_unlock(rwlock_t *lock)
 240{
 241        __raw_read_unlock(lock);
 242}
 243EXPORT_SYMBOL(_raw_read_unlock);
 244#endif
 245
 246#ifndef CONFIG_INLINE_READ_UNLOCK_IRQRESTORE
 247void __lockfunc _raw_read_unlock_irqrestore(rwlock_t *lock, unsigned long flags)
 248{
 249        __raw_read_unlock_irqrestore(lock, flags);
 250}
 251EXPORT_SYMBOL(_raw_read_unlock_irqrestore);
 252#endif
 253
 254#ifndef CONFIG_INLINE_READ_UNLOCK_IRQ
 255void __lockfunc _raw_read_unlock_irq(rwlock_t *lock)
 256{
 257        __raw_read_unlock_irq(lock);
 258}
 259EXPORT_SYMBOL(_raw_read_unlock_irq);
 260#endif
 261
 262#ifndef CONFIG_INLINE_READ_UNLOCK_BH
 263void __lockfunc _raw_read_unlock_bh(rwlock_t *lock)
 264{
 265        __raw_read_unlock_bh(lock);
 266}
 267EXPORT_SYMBOL(_raw_read_unlock_bh);
 268#endif
 269
 270#ifndef CONFIG_INLINE_WRITE_TRYLOCK
 271int __lockfunc _raw_write_trylock(rwlock_t *lock)
 272{
 273        return __raw_write_trylock(lock);
 274}
 275EXPORT_SYMBOL(_raw_write_trylock);
 276#endif
 277
 278#ifndef CONFIG_INLINE_WRITE_LOCK
 279void __lockfunc _raw_write_lock(rwlock_t *lock)
 280{
 281        __raw_write_lock(lock);
 282}
 283EXPORT_SYMBOL(_raw_write_lock);
 284#endif
 285
 286#ifndef CONFIG_INLINE_WRITE_LOCK_IRQSAVE
 287unsigned long __lockfunc _raw_write_lock_irqsave(rwlock_t *lock)
 288{
 289        return __raw_write_lock_irqsave(lock);
 290}
 291EXPORT_SYMBOL(_raw_write_lock_irqsave);
 292#endif
 293
 294#ifndef CONFIG_INLINE_WRITE_LOCK_IRQ
 295void __lockfunc _raw_write_lock_irq(rwlock_t *lock)
 296{
 297        __raw_write_lock_irq(lock);
 298}
 299EXPORT_SYMBOL(_raw_write_lock_irq);
 300#endif
 301
 302#ifndef CONFIG_INLINE_WRITE_LOCK_BH
 303void __lockfunc _raw_write_lock_bh(rwlock_t *lock)
 304{
 305        __raw_write_lock_bh(lock);
 306}
 307EXPORT_SYMBOL(_raw_write_lock_bh);
 308#endif
 309
 310#ifndef CONFIG_INLINE_WRITE_UNLOCK
 311void __lockfunc _raw_write_unlock(rwlock_t *lock)
 312{
 313        __raw_write_unlock(lock);
 314}
 315EXPORT_SYMBOL(_raw_write_unlock);
 316#endif
 317
 318#ifndef CONFIG_INLINE_WRITE_UNLOCK_IRQRESTORE
 319void __lockfunc _raw_write_unlock_irqrestore(rwlock_t *lock, unsigned long flags)
 320{
 321        __raw_write_unlock_irqrestore(lock, flags);
 322}
 323EXPORT_SYMBOL(_raw_write_unlock_irqrestore);
 324#endif
 325
 326#ifndef CONFIG_INLINE_WRITE_UNLOCK_IRQ
 327void __lockfunc _raw_write_unlock_irq(rwlock_t *lock)
 328{
 329        __raw_write_unlock_irq(lock);
 330}
 331EXPORT_SYMBOL(_raw_write_unlock_irq);
 332#endif
 333
 334#ifndef CONFIG_INLINE_WRITE_UNLOCK_BH
 335void __lockfunc _raw_write_unlock_bh(rwlock_t *lock)
 336{
 337        __raw_write_unlock_bh(lock);
 338}
 339EXPORT_SYMBOL(_raw_write_unlock_bh);
 340#endif
 341
 342#ifdef CONFIG_DEBUG_LOCK_ALLOC
 343
 344void __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}
 350EXPORT_SYMBOL(_raw_spin_lock_nested);
 351
 352unsigned 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}
 364EXPORT_SYMBOL(_raw_spin_lock_irqsave_nested);
 365
 366void __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}
 373EXPORT_SYMBOL(_raw_spin_lock_nest_lock);
 374
 375#endif
 376
 377notrace 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}
 385EXPORT_SYMBOL(in_lock_functions);
 386
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