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/*
* Copyright (c) 2012-2017 Richard Braun.
*
* 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 3 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.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#ifndef _KERN_SPINLOCK_I_H
#define _KERN_SPINLOCK_I_H
#include <assert.h>
#include <stddef.h>
#include <stdint.h>
#include <kern/atomic.h>
#include <kern/error.h>
#include <kern/macros.h>
#include <kern/spinlock_types.h>
#include <machine/cpu.h>
/*
* Non-contended lock values.
*
* Any other lock value implies a contended lock.
*/
#define SPINLOCK_UNLOCKED 0
#define SPINLOCK_LOCKED 1
static inline int
spinlock_lock_fast(struct spinlock *lock)
{
unsigned int prev;
prev = atomic_cas_acquire(&lock->value, SPINLOCK_UNLOCKED, SPINLOCK_LOCKED);
if (unlikely(prev != SPINLOCK_UNLOCKED)) {
return ERROR_BUSY;
}
return 0;
}
static inline int
spinlock_unlock_fast(struct spinlock *lock)
{
unsigned int prev;
prev = atomic_cas_release(&lock->value, SPINLOCK_LOCKED, SPINLOCK_UNLOCKED);
if (unlikely(prev != SPINLOCK_LOCKED)) {
return ERROR_BUSY;
}
return 0;
}
void spinlock_lock_slow(struct spinlock *lock);
void spinlock_unlock_slow(struct spinlock *lock);
static inline void
spinlock_lock_common(struct spinlock *lock)
{
int error;
error = spinlock_lock_fast(lock);
if (unlikely(error)) {
spinlock_lock_slow(lock);
}
}
static inline void
spinlock_unlock_common(struct spinlock *lock)
{
int error;
error = spinlock_unlock_fast(lock);
if (unlikely(error)) {
spinlock_unlock_slow(lock);
}
}
#endif /* _KERN_SPINLOCK_I_H */
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