540 lines
13 KiB
C
540 lines
13 KiB
C
/*
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* Copyright (c) 1995 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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#include <stdlib.h>
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#include <errno.h>
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#include <string.h>
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#include <pthread.h>
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#include "thr_private.h"
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/*
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* Proctect two different threads calling a pthread_cond_* function
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* from accidentally initializing the condition variable twice.
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*/
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static spinlock_t static_cond_lock = _SPINLOCK_INITIALIZER;
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/*
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* Prototypes
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*/
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static inline int cond_init(pthread_cond_t *);
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static pthread_t cond_queue_deq(pthread_cond_t);
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static void cond_queue_remove(pthread_cond_t, pthread_t);
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static void cond_queue_enq(pthread_cond_t, pthread_t);
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static int cond_signal(pthread_cond_t *, int);
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static int cond_wait_common(pthread_cond_t *,
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pthread_mutex_t *, const struct timespec *);
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__weak_reference(_pthread_cond_init, pthread_cond_init);
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__weak_reference(_pthread_cond_destroy, pthread_cond_destroy);
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__weak_reference(_pthread_cond_wait, pthread_cond_wait);
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__weak_reference(_pthread_cond_timedwait, pthread_cond_timedwait);
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__weak_reference(_pthread_cond_signal, pthread_cond_signal);
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__weak_reference(_pthread_cond_broadcast, pthread_cond_broadcast);
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#define COND_LOCK(c) \
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do { \
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if (umtx_lock(&(c)->c_lock, curthread->thr_id)) \
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abort(); \
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} while (0)
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#define COND_UNLOCK(c) \
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do { \
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if (umtx_unlock(&(c)->c_lock, curthread->thr_id)) \
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abort(); \
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} while (0)
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/* Reinitialize a condition variable to defaults. */
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int
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_cond_reinit(pthread_cond_t *cond)
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{
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if (cond == NULL)
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return (EINVAL);
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if (*cond == NULL)
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return (pthread_cond_init(cond, NULL));
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/*
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* Initialize the condition variable structure:
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*/
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TAILQ_INIT(&(*cond)->c_queue);
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(*cond)->c_flags = COND_FLAGS_INITED;
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(*cond)->c_type = COND_TYPE_FAST;
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(*cond)->c_mutex = NULL;
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(*cond)->c_seqno = 0;
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bzero(&(*cond)->c_lock, sizeof((*cond)->c_lock));
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return (0);
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}
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int
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_pthread_cond_init(pthread_cond_t *cond, const pthread_condattr_t *cond_attr)
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{
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enum pthread_cond_type type;
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pthread_cond_t pcond;
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if (cond == NULL)
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return (EINVAL);
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/*
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* Check if a pointer to a condition variable attribute
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* structure was passed by the caller:
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*/
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if (cond_attr != NULL && *cond_attr != NULL)
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type = (*cond_attr)->c_type;
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else
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/* Default to a fast condition variable: */
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type = COND_TYPE_FAST;
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/* Process according to condition variable type: */
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switch (type) {
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case COND_TYPE_FAST:
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break;
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default:
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return (EINVAL);
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break;
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}
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if ((pcond = (pthread_cond_t)
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malloc(sizeof(struct pthread_cond))) == NULL)
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return (ENOMEM);
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/*
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* Initialise the condition variable
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* structure:
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*/
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TAILQ_INIT(&pcond->c_queue);
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pcond->c_flags |= COND_FLAGS_INITED;
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pcond->c_type = type;
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pcond->c_mutex = NULL;
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pcond->c_seqno = 0;
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bzero(&pcond->c_lock, sizeof(pcond->c_lock));
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*cond = pcond;
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return (0);
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}
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int
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_pthread_cond_destroy(pthread_cond_t *cond)
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{
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if (cond == NULL || *cond == NULL)
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return (EINVAL);
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COND_LOCK(*cond);
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/*
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* Free the memory allocated for the condition
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* variable structure:
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*/
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free(*cond);
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/*
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* NULL the caller's pointer now that the condition
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* variable has been destroyed:
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*/
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*cond = NULL;
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return (0);
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}
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int
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_pthread_cond_wait(pthread_cond_t *cond, pthread_mutex_t *mutex)
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{
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int rval;
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rval = cond_wait_common(cond, mutex, NULL);
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/* This should never happen. */
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if (rval == ETIMEDOUT)
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abort();
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return (rval);
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}
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int
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_pthread_cond_timedwait(pthread_cond_t * cond, pthread_mutex_t * mutex,
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const struct timespec * abstime)
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{
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if (abstime == NULL || abstime->tv_nsec >= 1000000000)
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return (EINVAL);
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return (cond_wait_common(cond, mutex, abstime));
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}
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static int
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cond_wait_common(pthread_cond_t * cond, pthread_mutex_t * mutex,
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const struct timespec * abstime)
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{
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int rval = 0;
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int done = 0;
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int seqno;
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int mtxrval;
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_thread_enter_cancellation_point();
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if (cond == NULL)
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return (EINVAL);
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/*
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* If the condition variable is statically initialized, perform dynamic
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* initialization.
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*/
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if (*cond == PTHREAD_COND_INITIALIZER && (rval = cond_init(cond)) != 0)
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return (rval);
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COND_LOCK(*cond);
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/*
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* If the condvar was statically allocated, properly
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* initialize the tail queue.
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*/
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if (((*cond)->c_flags & COND_FLAGS_INITED) == 0) {
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TAILQ_INIT(&(*cond)->c_queue);
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(*cond)->c_flags |= COND_FLAGS_INITED;
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}
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/* Process according to condition variable type. */
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switch ((*cond)->c_type) {
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/* Fast condition variable: */
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case COND_TYPE_FAST:
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if ((mutex == NULL) || (((*cond)->c_mutex != NULL) &&
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((*cond)->c_mutex != *mutex))) {
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COND_UNLOCK(*cond);
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rval = EINVAL;
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break;
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}
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/* Remember the mutex */
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(*cond)->c_mutex = *mutex;
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if ((rval = _mutex_cv_unlock(mutex)) != 0) {
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if (rval == -1){
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printf("foo");
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fflush(stdout);
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abort();
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}
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COND_UNLOCK(*cond);
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break;
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}
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/*
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* We need to protect the queue operations. It also
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* protects c_seqno and the pthread flag fields. This is
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* dropped before calling _thread_suspend() and reaquired
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* when we return.
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*/
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_thread_critical_enter(curthread);
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/*
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* c_seqno is protected.
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*/
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seqno = (*cond)->c_seqno;
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do {
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/*
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* Queue the running thread on the condition
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* variable.
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*/
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cond_queue_enq(*cond, curthread);
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if (curthread->cancelflags & PTHREAD_CANCELLING) {
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/*
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* POSIX Says that we must relock the mutex
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* even if we're being canceled.
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*/
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_thread_critical_exit(curthread);
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COND_UNLOCK(*cond);
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_mutex_cv_lock(mutex);
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pthread_testcancel();
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PANIC("Shouldn't have come back.");
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}
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PTHREAD_SET_STATE(curthread, PS_COND_WAIT);
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_thread_critical_exit(curthread);
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COND_UNLOCK(*cond);
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rval = _thread_suspend(curthread, (struct timespec *)abstime);
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if (rval == -1) {
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printf("foo");
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fflush(stdout);
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abort();
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}
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COND_LOCK(*cond);
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_thread_critical_enter(curthread);
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done = (seqno != (*cond)->c_seqno);
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/*
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* If we timed out, this will remove us from the
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* queue. Otherwise, if we were signaled it does
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* nothing because this thread won't be on the queue.
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*/
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cond_queue_remove(*cond, curthread);
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} while ((done == 0) && (rval == 0));
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/*
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* If we timed out someone still may have signaled us
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* before we got a chance to run again. We check for
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* this by looking to see if our state is RUNNING.
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*/
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if (rval == EAGAIN) {
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if (curthread->state != PS_RUNNING) {
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PTHREAD_SET_STATE(curthread, PS_RUNNING);
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rval = ETIMEDOUT;
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} else
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rval = 0;
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}
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_thread_critical_exit(curthread);
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COND_UNLOCK(*cond);
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mtxrval = _mutex_cv_lock(mutex);
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/*
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* If the mutex failed return that error, otherwise we're
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* returning ETIMEDOUT.
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*/
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if (mtxrval == -1) {
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printf("foo");
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fflush(stdout);
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abort();
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}
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if (mtxrval != 0)
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rval = mtxrval;
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break;
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/* Trap invalid condition variable types: */
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default:
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COND_UNLOCK(*cond);
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rval = EINVAL;
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break;
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}
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_thread_leave_cancellation_point();
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return (rval);
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}
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int
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_pthread_cond_signal(pthread_cond_t * cond)
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{
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return (cond_signal(cond, 0));
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}
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int
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_pthread_cond_broadcast(pthread_cond_t * cond)
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{
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return (cond_signal(cond, 1));
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}
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static int
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cond_signal(pthread_cond_t * cond, int broadcast)
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{
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int rval = 0;
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pthread_t pthread;
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if (cond == NULL)
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return (EINVAL);
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/*
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* If the condition variable is statically initialized, perform dynamic
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* initialization.
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*/
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if (*cond == PTHREAD_COND_INITIALIZER && (rval = cond_init(cond)) != 0)
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return (rval);
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COND_LOCK(*cond);
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/* Process according to condition variable type: */
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switch ((*cond)->c_type) {
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/* Fast condition variable: */
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case COND_TYPE_FAST:
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(*cond)->c_seqno++;
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/*
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* Enter a loop to bring all (or only one) threads off the
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* condition queue:
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*/
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do {
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/*
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* Wake up the signaled thread. It will be returned
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* to us locked, and with signals disabled.
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*/
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if ((pthread = cond_queue_deq(*cond)) != NULL) {
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PTHREAD_NEW_STATE(pthread, PS_RUNNING);
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_thread_critical_exit(pthread);
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}
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} while (broadcast && pthread != NULL);
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break;
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/* Trap invalid condition variable types: */
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default:
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rval = EINVAL;
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break;
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}
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COND_UNLOCK(*cond);
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return (rval);
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}
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void
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_cond_wait_backout(pthread_t pthread)
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{
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pthread_cond_t cond;
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cond = pthread->data.cond;
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if (cond == NULL)
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return;
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COND_LOCK(cond);
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/* Process according to condition variable type: */
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switch (cond->c_type) {
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/* Fast condition variable: */
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case COND_TYPE_FAST:
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_thread_critical_enter(curthread);
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cond_queue_remove(cond, pthread);
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_thread_critical_exit(curthread);
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break;
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default:
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break;
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}
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COND_UNLOCK(cond);
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}
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/*
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* Dequeue a waiting thread from the head of a condition queue in
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* descending priority order.
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*/
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static pthread_t
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cond_queue_deq(pthread_cond_t cond)
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{
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pthread_t pthread;
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while ((pthread = TAILQ_FIRST(&cond->c_queue)) != NULL) {
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_thread_critical_enter(pthread);
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TAILQ_REMOVE(&cond->c_queue, pthread, sqe);
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cond_queue_remove(cond, pthread);
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if ((pthread->cancelflags & PTHREAD_CANCELLING) == 0 &&
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pthread->state == PS_COND_WAIT)
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/*
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* Only exit the loop when we find a thread
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* that hasn't timed out or been canceled;
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* those threads are already running and don't
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* need their run state changed.
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*/
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break;
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else
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_thread_critical_exit(pthread);
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}
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return(pthread);
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}
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/*
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* Remove a waiting thread from a condition queue in descending priority
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* order.
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*/
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static void
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cond_queue_remove(pthread_cond_t cond, pthread_t pthread)
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{
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/*
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* Because pthread_cond_timedwait() can timeout as well
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* as be signaled by another thread, it is necessary to
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* guard against removing the thread from the queue if
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* it isn't in the queue.
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*/
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if (pthread->flags & PTHREAD_FLAGS_IN_CONDQ) {
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TAILQ_REMOVE(&cond->c_queue, pthread, sqe);
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pthread->flags &= ~PTHREAD_FLAGS_IN_CONDQ;
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}
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/* Check for no more waiters. */
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if (TAILQ_FIRST(&cond->c_queue) == NULL)
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cond->c_mutex = NULL;
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}
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/*
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* Enqueue a waiting thread to a condition queue in descending priority
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* order.
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*/
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static void
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cond_queue_enq(pthread_cond_t cond, pthread_t pthread)
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{
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pthread_t tid = TAILQ_LAST(&cond->c_queue, cond_head);
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char *name;
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name = pthread->name ? pthread->name : "unknown";
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if ((pthread->flags & PTHREAD_FLAGS_IN_CONDQ) != 0)
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_thread_printf(2, "Thread (%s:%u) already on condq\n",
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pthread->name, pthread->uniqueid);
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if ((pthread->flags & PTHREAD_FLAGS_IN_MUTEXQ) != 0)
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_thread_printf(2, "Thread (%s:%u) already on mutexq\n",
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pthread->name, pthread->uniqueid);
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PTHREAD_ASSERT_NOT_IN_SYNCQ(pthread);
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/*
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* For the common case of all threads having equal priority,
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* we perform a quick check against the priority of the thread
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* at the tail of the queue.
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*/
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if ((tid == NULL) || (pthread->active_priority <= tid->active_priority))
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TAILQ_INSERT_TAIL(&cond->c_queue, pthread, sqe);
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else {
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tid = TAILQ_FIRST(&cond->c_queue);
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while (pthread->active_priority <= tid->active_priority)
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tid = TAILQ_NEXT(tid, sqe);
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TAILQ_INSERT_BEFORE(tid, pthread, sqe);
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}
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pthread->flags |= PTHREAD_FLAGS_IN_CONDQ;
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pthread->data.cond = cond;
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}
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static inline int
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cond_init(pthread_cond_t *cond)
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{
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int error = 0;
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_SPINLOCK(&static_cond_lock);
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if (*cond == PTHREAD_COND_INITIALIZER)
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error = _pthread_cond_init(cond, NULL);
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_SPINUNLOCK(&static_cond_lock);
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return (error);
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}
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