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/*
* Copyright (c) 2013-2017 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/>.
*
*
* Mutual exclusion sleep locks.
*
* Unlike spin locks, acquiring a mutex may make the calling thread sleep.
*
* TODO Adaptive spinning.
*/
#ifndef _KERN_MUTEX_H
#define _KERN_MUTEX_H
#include <kern/init.h>
#include <kern/mutex_types.h>
#ifdef X15_MUTEX_PI
#include <kern/rtmutex.h>
struct mutex;
#define mutex_assert_locked(mutex) rtmutex_assert_locked(&(mutex)->rtmutex)
static inline void
mutex_init(struct mutex *mutex)
{
rtmutex_init(&mutex->rtmutex);
}
static inline int
mutex_trylock(struct mutex *mutex)
{
return rtmutex_trylock(&mutex->rtmutex);
}
static inline void
mutex_lock(struct mutex *mutex)
{
rtmutex_lock(&mutex->rtmutex);
}
static inline void
mutex_unlock(struct mutex *mutex)
{
rtmutex_unlock(&mutex->rtmutex);
/*
* If this mutex was used along with a condition variable, wake up
* a potential pending waiter. This must be done after the mutex is
* unlocked so that a higher priority thread can directly acquire it.
*/
thread_wakeup_last_cond();
}
#else /* X15_MUTEX_PI */
#include <assert.h>
#include <kern/error.h>
#include <kern/macros.h>
#include <kern/mutex_i.h>
#include <kern/thread.h>
struct mutex;
#define mutex_assert_locked(mutex) assert((mutex)->state != MUTEX_UNLOCKED)
/*
* Initialize a mutex.
*/
static inline void
mutex_init(struct mutex *mutex)
{
mutex->state = MUTEX_UNLOCKED;
}
/*
* Attempt to lock the given mutex.
*
* This function may not sleep.
*
* Return 0 on success, ERROR_BUSY if the mutex is already locked.
*/
static inline int
mutex_trylock(struct mutex *mutex)
{
unsigned int state;
state = mutex_lock_fast(mutex);
if (unlikely(state != MUTEX_UNLOCKED)) {
assert((state == MUTEX_LOCKED) || (state == MUTEX_CONTENDED));
return ERROR_BUSY;
}
return 0;
}
/*
* Lock a mutex.
*
* If the mutex is already locked, the calling thread sleeps until the
* mutex is unlocked.
*
* A mutex can only be locked once.
*/
static inline void
mutex_lock(struct mutex *mutex)
{
unsigned int state;
state = mutex_lock_fast(mutex);
if (unlikely(state != MUTEX_UNLOCKED)) {
assert((state == MUTEX_LOCKED) || (state == MUTEX_CONTENDED));
mutex_lock_slow(mutex);
}
}
/*
* Unlock a mutex.
*
* The mutex must be locked, and must have been locked by the calling
* thread.
*/
static inline void
mutex_unlock(struct mutex *mutex)
{
unsigned int state;
state = mutex_unlock_fast(mutex);
if (unlikely(state != MUTEX_LOCKED)) {
assert(state == MUTEX_CONTENDED);
mutex_unlock_slow(mutex);
}
/*
* If this mutex was used along with a condition variable, wake up
* a potential pending waiter.
*/
thread_wakeup_last_cond();
}
#endif /* X15_MUTEX_PI */
/*
* This init operation provides :
* - uncontended mutex locking
*
* Contended locking may only occur after starting the scheduler.
*/
INIT_OP_DECLARE(mutex_setup);
#endif /* _KERN_MUTEX_H */
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