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afa647196b
makeing sure the spinlock isn't already in use might be a nice feature to have in theory, it's hard to implement in practice since the passed in pointer may not be NULL, but still be an invalid value (i.e. 1..2..3.. etc).
176 lines
5.1 KiB
C
176 lines
5.1 KiB
C
/*
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* Copyright (c) 2004 Michael Telahun Makonnen <mtm@FreeBSD.Org>
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* Copyright (c) 1997 John Birrell <jb@cimlogic.com.au>.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by John Birrell.
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* 4. Neither the name of the author nor the names of any co-contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY JOHN BIRRELL AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* $FreeBSD$
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*
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*/
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#include <sys/types.h>
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#include <machine/atomic.h>
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#include <stdlib.h>
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#include <stdio.h>
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#include <string.h>
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#include <sched.h>
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#include <pthread.h>
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#include <unistd.h>
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#include <libc_private.h>
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#include "thr_private.h"
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#define THR_SPIN_MAGIC 0xdadadada
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#define THR_SPIN_UNOWNED (void *)0
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#define MAGIC_TEST_RETURN_ON_FAIL(l) \
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do { \
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if ((l) == NULL || (l)->s_magic != THR_SPIN_MAGIC) \
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return (EINVAL); \
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} while(0)
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__weak_reference(_pthread_spin_destroy, pthread_spin_destroy);
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__weak_reference(_pthread_spin_init, pthread_spin_init);
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__weak_reference(_pthread_spin_lock, pthread_spin_lock);
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__weak_reference(_pthread_spin_trylock, pthread_spin_trylock);
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__weak_reference(_pthread_spin_unlock, pthread_spin_unlock);
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int
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_pthread_spin_destroy(pthread_spinlock_t *lock)
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{
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MAGIC_TEST_RETURN_ON_FAIL((*lock));
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if ((*lock)->s_owner == THR_SPIN_UNOWNED) {
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(*lock)->s_magic = 0;
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free((*lock));
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*lock = NULL;
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return (0);
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}
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return (EBUSY);
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}
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int
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_pthread_spin_init(pthread_spinlock_t *lock, int pshared)
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{
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struct pthread_spinlock *s;
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s = (struct pthread_spinlock *)malloc(sizeof(struct pthread_spinlock));
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if (s == NULL)
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return (ENOMEM);
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s->s_magic = THR_SPIN_MAGIC;
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s->s_owner = THR_SPIN_UNOWNED;
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*lock = s;
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return (0);
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}
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/*
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* If the caller sets nonblocking to 1, this function will return
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* immediately without acquiring the lock it is owned by another thread.
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* If set to 0, it will keep spinning until it acquires the lock.
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*/
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int
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_pthread_spin_lock(pthread_spinlock_t *lock)
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{
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MAGIC_TEST_RETURN_ON_FAIL(*lock);
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if ((*lock)->s_owner == curthread)
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return (EDEADLK);
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while (atomic_cmpset_acq_ptr(&(*lock)->s_owner, THR_SPIN_UNOWNED,
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(void *)curthread) != 1)
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; /* SPIN */
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return (0);
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}
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int
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_pthread_spin_trylock(pthread_spinlock_t *lock)
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{
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MAGIC_TEST_RETURN_ON_FAIL(*lock);
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if (atomic_cmpset_acq_ptr(&(*lock)->s_owner, THR_SPIN_UNOWNED,
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(void *)curthread) == 1)
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return (0);
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return (EBUSY);
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}
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int
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_pthread_spin_unlock(pthread_spinlock_t *lock)
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{
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MAGIC_TEST_RETURN_ON_FAIL(*lock);
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if (atomic_cmpset_rel_ptr(&(*lock)->s_owner, (void *)curthread,
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THR_SPIN_UNOWNED) == 1)
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return (0);
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return (EPERM);
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}
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void
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_spinunlock(spinlock_t *lck)
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{
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if (umtx_unlock((struct umtx *)lck, curthread->thr_id))
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abort();
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}
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/*
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* Lock a location for the running thread. Yield to allow other
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* threads to run if this thread is blocked because the lock is
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* not available. Note that this function does not sleep. It
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* assumes that the lock will be available very soon.
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*/
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void
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_spinlock(spinlock_t *lck)
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{
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if (umtx_lock((struct umtx *)lck, curthread->thr_id))
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abort();
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}
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int
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_spintrylock(spinlock_t *lck)
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{
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int error;
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error = umtx_lock((struct umtx *)lck, curthread->thr_id);
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if (error != 0 && error != EBUSY)
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abort();
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return (error);
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}
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/*
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* Lock a location for the running thread. Yield to allow other
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* threads to run if this thread is blocked because the lock is
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* not available. Note that this function does not sleep. It
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* assumes that the lock will be available very soon.
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*
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* This function checks if the running thread has already locked the
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* location, warns if this occurs and creates a thread dump before
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* returning.
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*/
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void
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_spinlock_debug(spinlock_t *lck, char *fname, int lineno)
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{
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if (umtx_lock((struct umtx *)lck, curthread->thr_id))
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abort();
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}
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