Quelle spinlock.c Sprache: C

// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (2004) Linus Torvalds
*
* Author: Zwane Mwaikambo <zwane@fsmlabs.com>
*
* 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>

#ifdef CONFIG_MMIOWB
#ifndef arch_mmiowb_state
DEFINE_PER_CPU(struct mmiowb_state, __mmiowb_state);
EXPORT_PER_CPU_SYMBOL(__mmiowb_state);
#endif
#endif

/*
* 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
* spinlock : include/linux/spinlock_api_smp.h
* rwlock   : include/linux/rwlock_api_smp.h
*/
#else

/*
* Some architectures can relax in favour of the CPU owning the lock.
*/
#ifndef arch_read_relax
# define arch_read_relax(l) cpu_relax()
#endif
#ifndef arch_write_relax
# define arch_write_relax(l) cpu_relax()
#endif
#ifndef arch_spin_relax
# define arch_spin_relax(l) cpu_relax()
#endif

/*
* 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 embeds 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 preemptible if possible), and we also signal
* towards that other CPU that it should break the lock ASAP.
*/
#define BUILD_LOCK_OPS(op, locktype)     \
static void __lockfunc __raw_##op##_lock(locktype##_t *lock)  \
{         \
for (;;) {       \
  preempt_disable();     \
  if (likely(do_raw_##op##_trylock(lock)))  \
   break;      \
  preempt_enable();     \
         \
  arch_##op##_relax(&lock->raw_lock);   \
}        \
}         \
         \
static 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();     \
         \
  arch_##op##_relax(&lock->raw_lock);   \
}        \
         \
return flags;       \
}         \
         \
static void __lockfunc __raw_##op##_lock_irq(locktype##_t *lock) \
{         \
_raw_##op##_lock_irqsave(lock);     \
}         \
         \
static 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);

#ifndef CONFIG_PREEMPT_RT
BUILD_LOCK_OPS(read, rwlock);
BUILD_LOCK_OPS(write, rwlock);
#endif

#endif

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

#ifndef CONFIG_PREEMPT_RT

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

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

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

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

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

#ifndef CONFIG_DEBUG_LOCK_ALLOC
#define __raw_write_lock_nested(lock, subclass) __raw_write_lock(((void)(subclass), (lock)))
#endif

void __lockfunc _raw_write_lock_nested(rwlock_t *lock, int subclass)
{
__raw_write_lock_nested(lock, subclass);
}
EXPORT_SYMBOL(_raw_write_lock_nested);
#endif

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

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

#endif /* !CONFIG_PREEMPT_RT */

#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(lock, do_raw_spin_trylock, do_raw_spin_lock);
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);

#if defined(CONFIG_PROVE_LOCKING) && defined(CONFIG_PREEMPT_RT)
void notrace lockdep_assert_in_softirq_func(void)
{
lockdep_assert_in_softirq();
}
EXPORT_SYMBOL(lockdep_assert_in_softirq_func);
#endif

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