a4c1887d4c
The arch_{read,spin,write}_lock_flags() macros are simply mapped to the
non-flags versions by the majority of architectures, so do this in core
code and remove the dummy implementations. Also remove the implementation
in spinlock_up.h, since all callers of do_raw_spin_lock_flags() call
local_irq_save(flags) anyway.
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: paulmck@linux.vnet.ibm.com
Link: http://lkml.kernel.org/r/1507055129-12300-4-git-send-email-will.deacon@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
126 lines
3.7 KiB
C
126 lines
3.7 KiB
C
/*
|
|
* Queued spinlock
|
|
*
|
|
* This program is free software; you can redistribute it and/or modify
|
|
* it under the terms of the GNU General Public License as published by
|
|
* the Free Software Foundation; either version 2 of the License, or
|
|
* (at your option) any later version.
|
|
*
|
|
* This program is distributed in the hope that it will be useful,
|
|
* but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
* GNU General Public License for more details.
|
|
*
|
|
* (C) Copyright 2013-2015 Hewlett-Packard Development Company, L.P.
|
|
* (C) Copyright 2015 Hewlett-Packard Enterprise Development LP
|
|
*
|
|
* Authors: Waiman Long <waiman.long@hpe.com>
|
|
*/
|
|
#ifndef __ASM_GENERIC_QSPINLOCK_H
|
|
#define __ASM_GENERIC_QSPINLOCK_H
|
|
|
|
#include <asm-generic/qspinlock_types.h>
|
|
|
|
/**
|
|
* queued_spin_is_locked - is the spinlock locked?
|
|
* @lock: Pointer to queued spinlock structure
|
|
* Return: 1 if it is locked, 0 otherwise
|
|
*/
|
|
#ifndef queued_spin_is_locked
|
|
static __always_inline int queued_spin_is_locked(struct qspinlock *lock)
|
|
{
|
|
/*
|
|
* Any !0 state indicates it is locked, even if _Q_LOCKED_VAL
|
|
* isn't immediately observable.
|
|
*/
|
|
return atomic_read(&lock->val);
|
|
}
|
|
#endif
|
|
|
|
/**
|
|
* queued_spin_value_unlocked - is the spinlock structure unlocked?
|
|
* @lock: queued spinlock structure
|
|
* Return: 1 if it is unlocked, 0 otherwise
|
|
*
|
|
* N.B. Whenever there are tasks waiting for the lock, it is considered
|
|
* locked wrt the lockref code to avoid lock stealing by the lockref
|
|
* code and change things underneath the lock. This also allows some
|
|
* optimizations to be applied without conflict with lockref.
|
|
*/
|
|
static __always_inline int queued_spin_value_unlocked(struct qspinlock lock)
|
|
{
|
|
return !atomic_read(&lock.val);
|
|
}
|
|
|
|
/**
|
|
* queued_spin_is_contended - check if the lock is contended
|
|
* @lock : Pointer to queued spinlock structure
|
|
* Return: 1 if lock contended, 0 otherwise
|
|
*/
|
|
static __always_inline int queued_spin_is_contended(struct qspinlock *lock)
|
|
{
|
|
return atomic_read(&lock->val) & ~_Q_LOCKED_MASK;
|
|
}
|
|
/**
|
|
* queued_spin_trylock - try to acquire the queued spinlock
|
|
* @lock : Pointer to queued spinlock structure
|
|
* Return: 1 if lock acquired, 0 if failed
|
|
*/
|
|
static __always_inline int queued_spin_trylock(struct qspinlock *lock)
|
|
{
|
|
if (!atomic_read(&lock->val) &&
|
|
(atomic_cmpxchg_acquire(&lock->val, 0, _Q_LOCKED_VAL) == 0))
|
|
return 1;
|
|
return 0;
|
|
}
|
|
|
|
extern void queued_spin_lock_slowpath(struct qspinlock *lock, u32 val);
|
|
|
|
/**
|
|
* queued_spin_lock - acquire a queued spinlock
|
|
* @lock: Pointer to queued spinlock structure
|
|
*/
|
|
static __always_inline void queued_spin_lock(struct qspinlock *lock)
|
|
{
|
|
u32 val;
|
|
|
|
val = atomic_cmpxchg_acquire(&lock->val, 0, _Q_LOCKED_VAL);
|
|
if (likely(val == 0))
|
|
return;
|
|
queued_spin_lock_slowpath(lock, val);
|
|
}
|
|
|
|
#ifndef queued_spin_unlock
|
|
/**
|
|
* queued_spin_unlock - release a queued spinlock
|
|
* @lock : Pointer to queued spinlock structure
|
|
*/
|
|
static __always_inline void queued_spin_unlock(struct qspinlock *lock)
|
|
{
|
|
/*
|
|
* unlock() needs release semantics:
|
|
*/
|
|
(void)atomic_sub_return_release(_Q_LOCKED_VAL, &lock->val);
|
|
}
|
|
#endif
|
|
|
|
#ifndef virt_spin_lock
|
|
static __always_inline bool virt_spin_lock(struct qspinlock *lock)
|
|
{
|
|
return false;
|
|
}
|
|
#endif
|
|
|
|
/*
|
|
* Remapping spinlock architecture specific functions to the corresponding
|
|
* queued spinlock functions.
|
|
*/
|
|
#define arch_spin_is_locked(l) queued_spin_is_locked(l)
|
|
#define arch_spin_is_contended(l) queued_spin_is_contended(l)
|
|
#define arch_spin_value_unlocked(l) queued_spin_value_unlocked(l)
|
|
#define arch_spin_lock(l) queued_spin_lock(l)
|
|
#define arch_spin_trylock(l) queued_spin_trylock(l)
|
|
#define arch_spin_unlock(l) queued_spin_unlock(l)
|
|
|
|
#endif /* __ASM_GENERIC_QSPINLOCK_H */
|