spinlock.c

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/*
 * Copyright (2004) Linus Torvalds
 *
 * Author: Zwane Mwaikambo <[email protected]>
 *
 * Copyright (2004, 2005) Ingo Molnar
 *
 * This file contains the spinlock/rwlock implementations for the
 * SMP and the DEBUG_SPINLOCK cases. (UP-nondebug inlines them)
 *
 * Note that some architectures have special knowledge about the
 * stack frames of these functions in their profile_pc. If you
 * change anything significant here that could change the stack
 * frame contact the architecture maintainers.
 */

#include <linux/linkage.h>
#include <linux/preempt.h>
#include <linux/spinlock.h>
#include <linux/interrupt.h>
#include <linux/debug_locks.h>
#include <linux/export.h>

/*
 * If lockdep is enabled then we use the non-preemption spin-ops
 * even on CONFIG_PREEMPT, because lockdep assumes that interrupts are
 * not re-enabled during lock-acquire (which the preempt-spin-ops do):
 */
#if !defined(CONFIG_GENERIC_LOCKBREAK) || defined(CONFIG_DEBUG_LOCK_ALLOC)
/*
 * The __lock_function inlines are taken from
 * include/linux/spinlock_api_smp.h
 */
#else
#define raw_read_can_lock(l)    read_can_lock(l)
#define raw_write_can_lock(l)   write_can_lock(l)
/*
 * We build the __lock_function inlines here. They are too large for
 * inlining all over the place, but here is only one user per function
 * which embedds them into the calling _lock_function below.
 *
 * This could be a long-held lock. We both prepare to spin for a long
 * time (making _this_ CPU preemptable if possible), and we also signal
 * towards that other CPU that it should break the lock ASAP.
 */
#define BUILD_LOCK_OPS(op, locktype)                    \
void __lockfunc __raw_##op##_lock(locktype##_t *lock)           \
{                                   \
    for (;;) {                          \
        preempt_disable();                  \
        if (likely(do_raw_##op##_trylock(lock)))        \
            break;                      \
        preempt_enable();                   \
                                    \
        if (!(lock)->break_lock)                \
            (lock)->break_lock = 1;             \
        while (!raw_##op##_can_lock(lock) && (lock)->break_lock)\
            arch_##op##_relax(&lock->raw_lock);     \
    }                               \
    (lock)->break_lock = 0;                     \
}                                   \
                                    \
unsigned long __lockfunc __raw_##op##_lock_irqsave(locktype##_t *lock)  \
{                                   \
    unsigned long flags;                        \
                                    \
    for (;;) {                          \
        preempt_disable();                  \
        local_irq_save(flags);                  \
        if (likely(do_raw_##op##_trylock(lock)))        \
            break;                      \
        local_irq_restore(flags);               \
        preempt_enable();                   \
                                    \
        if (!(lock)->break_lock)                \
            (lock)->break_lock = 1;             \
        while (!raw_##op##_can_lock(lock) && (lock)->break_lock)\
            arch_##op##_relax(&lock->raw_lock);     \
    }                               \
    (lock)->break_lock = 0;                     \
    return flags;                           \
}                                   \
                                    \
void __lockfunc __raw_##op##_lock_irq(locktype##_t *lock)       \
{                                   \
    _raw_##op##_lock_irqsave(lock);                 \
}                                   \
                                    \
void __lockfunc __raw_##op##_lock_bh(locktype##_t *lock)        \
{                                   \
    unsigned long flags;                        \
                                    \
    /*                          */  \
    /* Careful: we must exclude softirqs too, hence the */  \
    /* irq-disabling. We use the generic preemption-aware   */  \
    /* function:                        */  \
                                    \
    flags = _raw_##op##_lock_irqsave(lock);             \
    local_bh_disable();                     \
    local_irq_restore(flags);                   \
}                                   \

/*
 * Build preemption-friendly versions of the following
 * lock-spinning functions:
 *
 *         __[spin|read|write]_lock()
 *         __[spin|read|write]_lock_irq()
 *         __[spin|read|write]_lock_irqsave()
 *         __[spin|read|write]_lock_bh()
 */
BUILD_LOCK_OPS(spin, raw_spinlock);
BUILD_LOCK_OPS(read, rwlock);
BUILD_LOCK_OPS(write, rwlock);

#endif

#ifndef CONFIG_INLINE_SPIN_TRYLOCK
int __lockfunc _raw_spin_trylock(raw_spinlock_t *lock)
{
    return __raw_spin_trylock(lock);
}
EXPORT_SYMBOL(_raw_spin_trylock);
#endif

#ifndef CONFIG_INLINE_SPIN_TRYLOCK_BH
int __lockfunc _raw_spin_trylock_bh(raw_spinlock_t *lock)
{
    return __raw_spin_trylock_bh(lock);
}
EXPORT_SYMBOL(_raw_spin_trylock_bh);
#endif

#ifndef CONFIG_INLINE_SPIN_LOCK
void __lockfunc _raw_spin_lock(raw_spinlock_t *lock)
{
    __raw_spin_lock(lock);
}
EXPORT_SYMBOL(_raw_spin_lock);
#endif

#ifndef CONFIG_INLINE_SPIN_LOCK_IRQSAVE
unsigned long __lockfunc _raw_spin_lock_irqsave(raw_spinlock_t *lock)
{
    return __raw_spin_lock_irqsave(lock);
}
EXPORT_SYMBOL(_raw_spin_lock_irqsave);
#endif

#ifndef CONFIG_INLINE_SPIN_LOCK_IRQ
void __lockfunc _raw_spin_lock_irq(raw_spinlock_t *lock)
{
    __raw_spin_lock_irq(lock);
}
EXPORT_SYMBOL(_raw_spin_lock_irq);
#endif

#ifndef CONFIG_INLINE_SPIN_LOCK_BH
void __lockfunc _raw_spin_lock_bh(raw_spinlock_t *lock)
{
    __raw_spin_lock_bh(lock);
}
EXPORT_SYMBOL(_raw_spin_lock_bh);
#endif

#ifdef CONFIG_UNINLINE_SPIN_UNLOCK
void __lockfunc _raw_spin_unlock(raw_spinlock_t *lock)
{
    __raw_spin_unlock(lock);
}
EXPORT_SYMBOL(_raw_spin_unlock);
#endif

#ifndef CONFIG_INLINE_SPIN_UNLOCK_IRQRESTORE
void __lockfunc _raw_spin_unlock_irqrestore(raw_spinlock_t *lock, unsigned long flags)
{
    __raw_spin_unlock_irqrestore(lock, flags);
}
EXPORT_SYMBOL(_raw_spin_unlock_irqrestore);
#endif

#ifndef CONFIG_INLINE_SPIN_UNLOCK_IRQ
void __lockfunc _raw_spin_unlock_irq(raw_spinlock_t *lock)
{
    __raw_spin_unlock_irq(lock);
}
EXPORT_SYMBOL(_raw_spin_unlock_irq);
#endif

#ifndef CONFIG_INLINE_SPIN_UNLOCK_BH
void __lockfunc _raw_spin_unlock_bh(raw_spinlock_t *lock)
{
    __raw_spin_unlock_bh(lock);
}
EXPORT_SYMBOL(_raw_spin_unlock_bh);
#endif

#ifndef CONFIG_INLINE_READ_TRYLOCK
int __lockfunc _raw_read_trylock(rwlock_t *lock)
{
    return __raw_read_trylock(lock);
}
EXPORT_SYMBOL(_raw_read_trylock);
#endif

#ifndef CONFIG_INLINE_READ_LOCK
void __lockfunc _raw_read_lock(rwlock_t *lock)
{
    __raw_read_lock(lock);
}
EXPORT_SYMBOL(_raw_read_lock);
#endif

#ifndef CONFIG_INLINE_READ_LOCK_IRQSAVE
unsigned long __lockfunc _raw_read_lock_irqsave(rwlock_t *lock)
{
    return __raw_read_lock_irqsave(lock);
}
EXPORT_SYMBOL(_raw_read_lock_irqsave);
#endif

#ifndef CONFIG_INLINE_READ_LOCK_IRQ
void __lockfunc _raw_read_lock_irq(rwlock_t *lock)
{
    __raw_read_lock_irq(lock);
}
EXPORT_SYMBOL(_raw_read_lock_irq);
#endif

#ifndef CONFIG_INLINE_READ_LOCK_BH
void __lockfunc _raw_read_lock_bh(rwlock_t *lock)
{
    __raw_read_lock_bh(lock);
}
EXPORT_SYMBOL(_raw_read_lock_bh);
#endif

#ifndef CONFIG_INLINE_READ_UNLOCK
void __lockfunc _raw_read_unlock(rwlock_t *lock)
{
    __raw_read_unlock(lock);
}
EXPORT_SYMBOL(_raw_read_unlock);
#endif

#ifndef CONFIG_INLINE_READ_UNLOCK_IRQRESTORE
void __lockfunc _raw_read_unlock_irqrestore(rwlock_t *lock, unsigned long flags)
{
    __raw_read_unlock_irqrestore(lock, flags);
}
EXPORT_SYMBOL(_raw_read_unlock_irqrestore);
#endif

#ifndef CONFIG_INLINE_READ_UNLOCK_IRQ
void __lockfunc _raw_read_unlock_irq(rwlock_t *lock)
{
    __raw_read_unlock_irq(lock);
}
EXPORT_SYMBOL(_raw_read_unlock_irq);
#endif

#ifndef CONFIG_INLINE_READ_UNLOCK_BH
void __lockfunc _raw_read_unlock_bh(rwlock_t *lock)
{
    __raw_read_unlock_bh(lock);
}
EXPORT_SYMBOL(_raw_read_unlock_bh);
#endif

#ifndef CONFIG_INLINE_WRITE_TRYLOCK
int __lockfunc _raw_write_trylock(rwlock_t *lock)
{
    return __raw_write_trylock(lock);
}
EXPORT_SYMBOL(_raw_write_trylock);
#endif

#ifndef CONFIG_INLINE_WRITE_LOCK
void __lockfunc _raw_write_lock(rwlock_t *lock)
{
    __raw_write_lock(lock);
}
EXPORT_SYMBOL(_raw_write_lock);
#endif

#ifndef CONFIG_INLINE_WRITE_LOCK_IRQSAVE
unsigned long __lockfunc _raw_write_lock_irqsave(rwlock_t *lock)
{
    return __raw_write_lock_irqsave(lock);
}
EXPORT_SYMBOL(_raw_write_lock_irqsave);
#endif

#ifndef CONFIG_INLINE_WRITE_LOCK_IRQ
void __lockfunc _raw_write_lock_irq(rwlock_t *lock)
{
    __raw_write_lock_irq(lock);
}
EXPORT_SYMBOL(_raw_write_lock_irq);
#endif

#ifndef CONFIG_INLINE_WRITE_LOCK_BH
void __lockfunc _raw_write_lock_bh(rwlock_t *lock)
{
    __raw_write_lock_bh(lock);
}
EXPORT_SYMBOL(_raw_write_lock_bh);
#endif

#ifndef CONFIG_INLINE_WRITE_UNLOCK
void __lockfunc _raw_write_unlock(rwlock_t *lock)
{
    __raw_write_unlock(lock);
}
EXPORT_SYMBOL(_raw_write_unlock);
#endif

#ifndef CONFIG_INLINE_WRITE_UNLOCK_IRQRESTORE
void __lockfunc _raw_write_unlock_irqrestore(rwlock_t *lock, unsigned long flags)
{
    __raw_write_unlock_irqrestore(lock, flags);
}
EXPORT_SYMBOL(_raw_write_unlock_irqrestore);
#endif

#ifndef CONFIG_INLINE_WRITE_UNLOCK_IRQ
void __lockfunc _raw_write_unlock_irq(rwlock_t *lock)
{
    __raw_write_unlock_irq(lock);
}
EXPORT_SYMBOL(_raw_write_unlock_irq);
#endif

#ifndef CONFIG_INLINE_WRITE_UNLOCK_BH
void __lockfunc _raw_write_unlock_bh(rwlock_t *lock)
{
    __raw_write_unlock_bh(lock);
}
EXPORT_SYMBOL(_raw_write_unlock_bh);
#endif

#ifdef CONFIG_DEBUG_LOCK_ALLOC

void __lockfunc _raw_spin_lock_nested(raw_spinlock_t *lock, int subclass)
{
    preempt_disable();
    spin_acquire(&lock->dep_map, subclass, 0, _RET_IP_);
    LOCK_CONTENDED(lock, do_raw_spin_trylock, do_raw_spin_lock);
}
EXPORT_SYMBOL(_raw_spin_lock_nested);

unsigned long __lockfunc _raw_spin_lock_irqsave_nested(raw_spinlock_t *lock,
                           int subclass)
{
    unsigned long flags;

    local_irq_save(flags);
    preempt_disable();
    spin_acquire(&lock->dep_map, subclass, 0, _RET_IP_);
    LOCK_CONTENDED_FLAGS(lock, do_raw_spin_trylock, do_raw_spin_lock,
                do_raw_spin_lock_flags, &flags);
    return flags;
}
EXPORT_SYMBOL(_raw_spin_lock_irqsave_nested);

void __lockfunc _raw_spin_lock_nest_lock(raw_spinlock_t *lock,
                     struct lockdep_map *nest_lock)
{
    preempt_disable();
    spin_acquire_nest(&lock->dep_map, 0, 0, nest_lock, _RET_IP_);
    LOCK_CONTENDED(lock, do_raw_spin_trylock, do_raw_spin_lock);
}
EXPORT_SYMBOL(_raw_spin_lock_nest_lock);

#endif

notrace int in_lock_functions(unsigned long addr)
{
    /* Linker adds these: start and end of __lockfunc functions */
    extern char __lock_text_start[], __lock_text_end[];

    return addr >= (unsigned long)__lock_text_start
    && addr < (unsigned long)__lock_text_end;
}
EXPORT_SYMBOL(in_lock_functions);