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/*
* Copyright (c) 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/>.
*
*
* Mutual exclusion locks.
*
* Unlike spin locks, acquiring a mutex may make the calling thread sleep.
*/
#ifndef _KERN_MUTEX_H
#define _KERN_MUTEX_H
#include <kern/assert.h>
#include <kern/list.h>
#include <kern/spinlock.h>
#include <kern/thread.h>
#define MUTEX_UNLOCKED 0
#define MUTEX_LOCKED 1
#define MUTEX_CONTENDED 2
struct mutex_waiter {
struct list node;
struct thread *thread;
};
struct mutex {
unsigned long state;
struct spinlock lock;
struct list waiters;
};
#define MUTEX_INITIALIZER(mutex) \
{ MUTEX_UNLOCKED, SPINLOCK_INITIALIZER, LIST_INITIALIZER((mutex).waiters) }
void mutex_init(struct mutex *mutex);
#define mutex_assert_locked(mutex) assert((mutex)->state != MUTEX_UNLOCKED)
/*
* Return 0 on success, 1 if busy.
*/
int mutex_trylock(struct mutex *mutex);
void mutex_lock(struct mutex *mutex);
void mutex_unlock(struct mutex *mutex);
#endif /* _KERN_MUTEX_H */
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