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/*
* Copyright (c) 2012, 2013 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/>.
*
*
* Spin lock.
*
* Critical sections built with spin locks run with preemption disabled.
*/
#ifndef _KERN_SPINLOCK_H
#define _KERN_SPINLOCK_H
#include <kern/assert.h>
#include <kern/macros.h>
#include <kern/spinlock_i.h>
#include <kern/thread.h>
#include <machine/cpu.h>
struct spinlock;
#define SPINLOCK_INITIALIZER { 0 }
static inline void
spinlock_init(struct spinlock *lock)
{
lock->locked = 0;
}
#define spinlock_assert_locked(lock) assert((lock)->locked)
/*
* Return 0 on success, 1 if busy.
*/
static inline int
spinlock_trylock(struct spinlock *lock)
{
int busy;
thread_preempt_disable();
busy = spinlock_tryacquire(lock);
if (busy)
thread_preempt_enable();
return busy;
}
static inline void
spinlock_lock(struct spinlock *lock)
{
thread_preempt_disable();
spinlock_acquire(lock);
}
static inline void
spinlock_unlock(struct spinlock *lock)
{
spinlock_release(lock);
thread_preempt_enable();
}
/*
* Versions of the spinlock functions that also disable interrupts during
* critical sections.
*/
static inline int
spinlock_trylock_intr_save(struct spinlock *lock, unsigned long *flags)
{
int busy;
thread_preempt_disable();
*flags = cpu_intr_save();
busy = spinlock_tryacquire(lock);
if (busy) {
cpu_intr_restore(*flags);
thread_preempt_enable();
}
return busy;
}
static inline void
spinlock_lock_intr_save(struct spinlock *lock, unsigned long *flags)
{
thread_preempt_disable();
*flags = cpu_intr_save();
spinlock_acquire(lock);
}
static inline void
spinlock_unlock_intr_restore(struct spinlock *lock, unsigned long flags)
{
spinlock_release(lock);
cpu_intr_restore(flags);
thread_preempt_enable();
}
#endif /* _KERN_SPINLOCK_H */
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