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/*
* Copyright (c) 1998, 1999 University of Utah and the Flux Group.
* All rights reserved.
*
* This file is part of the Flux OSKit. The OSKit is free software, also known
* as "open source;" you can redistribute it and/or modify it under the terms
* of the GNU General Public License (GPL), version 2, as published by the Free
* Software Foundation (FSF). To explore alternate licensing terms, contact
* the University of Utah at csl-dist@cs.utah.edu or +1-801-585-3271.
*
* The OSKit 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 GPL for more details. You should have
* received a copy of the GPL along with the OSKit; see the file COPYING. If
* not, write to the FSF, 59 Temple Place #330, Boston, MA 02111-1307, USA.
*/
/*
* Internal mutex implementation.
*/
struct pthread_mutex_impl {
spin_lock_t mlock; /* Actual mutex lock */
spin_lock_t dlock; /* Lock for this data structure */
queue_head_t waiters; /* queue for mutex */
void *holder; /* Opaque to user */
int count; /* For recursive mutexes */
int inherit; /* Does priority inheritance */
int type; /* Mutex type. See below */
};
/*
* Inline mutex functions.
*
* NOTE: These assume the spl level is set properly before being called.
*/
/*
* Internal function. Try to lock a mutex. Spinning version.
*/
OSKIT_INLINE int
fast_mutex_spinlock(pthread_mutex_t *m)
{
struct pthread_mutex_impl *pimpl = m->impl;
while (1) {
pthread_lock(&pimpl->mlock);
/*
* Try to get the lock. If successful, set owner and count.
*/
if (pimpl->holder == 0) {
pimpl->holder = (void *) CURPTHREAD();
pimpl->count = 1;
pthread_unlock(&pimpl->mlock);
return 0;
}
pthread_unlock(&pimpl->mlock);
}
}
OSKIT_INLINE int
fast_mutex_lock(pthread_mutex_t *m)
{
struct pthread_mutex_impl *pimpl = m->impl;
pthread_lock(&pimpl->mlock);
/*
* Try to get the lock. If successful, set owner and count.
*/
if (pimpl->holder == 0) {
pimpl->holder = (void *) CURPTHREAD();
pimpl->count = 1;
pthread_unlock(&pimpl->mlock);
return 0;
}
pthread_unlock(&pimpl->mlock);
return pthread_mutex_lock(m);
}
OSKIT_INLINE int
fast_mutex_unlock(pthread_mutex_t *m)
{
struct pthread_mutex_impl *pimpl = m->impl;
pthread_lock(&pimpl->mlock);
/*
* If the queue is empty, the mutex is free, and the lock can be
* released.
*/
if (queue_empty(&(pimpl->waiters))) {
pimpl->holder = NULL_THREADPTR;
pimpl->count = 0;
pthread_unlock(&pimpl->mlock);
return 0;
}
/*
* Take the slow boat.
*/
pthread_unlock(&pimpl->mlock);
return pthread_mutex_unlock(m);
}
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