mirror of
https://github.com/torvalds/linux.git
synced 2024-12-06 19:11:31 +00:00
8282947f67
Similar to rw_semaphores, on RT the rwlock substitution is not writer fair, because it's not feasible to have a writer inherit its priority to multiple readers. Readers blocked on a writer follow the normal rules of priority inheritance. Like RT spinlocks, RT rwlocks are state preserving across the slow lock operations (contended case). Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Link: https://lore.kernel.org/r/20210815211303.882793524@linutronix.de
407 lines
9.7 KiB
C
407 lines
9.7 KiB
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) \
|
|
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); \
|
|
} \
|
|
} \
|
|
\
|
|
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; \
|
|
} \
|
|
\
|
|
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);
|
|
|
|
#ifndef CONFIG_PREEMPT_RT
|
|
BUILD_LOCK_OPS(read, rwlock);
|
|
BUILD_LOCK_OPS(write, rwlock);
|
|
#endif
|
|
|
|
#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_PREEMPT_RT
|
|
|
|
#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
|
|
|
|
#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_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);
|