447 lines
11 KiB
C
447 lines
11 KiB
C
/* $NetBSD: sem.c,v 1.13 2007/03/05 23:56:44 ad Exp $ */
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/*-
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* Copyright (c) 2003, 2006, 2007 The NetBSD Foundation, Inc.
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* All rights reserved.
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*
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* This code is derived from software contributed to The NetBSD Foundation
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* by Jason R. Thorpe of Wasabi Systems, Inc, and by Andrew Doran.
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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 the NetBSD
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* Foundation, Inc. and its contributors.
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* 4. Neither the name of The NetBSD Foundation nor the names of its
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* contributors may be used to endorse or promote products derived
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* from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
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* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
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* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*/
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/*
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* Copyright (C) 2000 Jason Evans <jasone@freebsd.org>.
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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(s), this list of conditions and the following disclaimer as
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* the first lines of this file unmodified other than the possible
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* addition of one or more copyright notices.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice(s), this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER(S) ``AS IS'' AND ANY
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* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER(S) BE
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* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
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* BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
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* WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
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* OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
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* EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#include <sys/cdefs.h>
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__RCSID("$NetBSD: sem.c,v 1.13 2007/03/05 23:56:44 ad Exp $");
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#include <sys/types.h>
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#include <sys/ksem.h>
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#include <sys/queue.h>
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#include <stdlib.h>
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#include <errno.h>
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#include <fcntl.h>
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#include <semaphore.h>
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#include <stdarg.h>
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#include "pthread.h"
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#include "pthread_int.h"
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struct _sem_st {
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unsigned int usem_magic;
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#define USEM_MAGIC 0x09fa4012
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LIST_ENTRY(_sem_st) usem_list;
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semid_t usem_semid; /* 0 -> user (non-shared) */
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#define USEM_USER 0 /* assumes kernel does not use NULL */
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sem_t *usem_identity;
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/* Protects data below. */
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pthread_spin_t usem_interlock;
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struct pthread_queue_t usem_waiters;
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unsigned int usem_count;
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};
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static int sem_alloc(unsigned int value, semid_t semid, sem_t *semp);
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static void sem_free(sem_t sem);
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static LIST_HEAD(, _sem_st) named_sems = LIST_HEAD_INITIALIZER(&named_sems);
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static pthread_mutex_t named_sems_mtx = PTHREAD_MUTEX_INITIALIZER;
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static void
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sem_free(sem_t sem)
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{
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sem->usem_magic = 0;
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free(sem);
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}
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static int
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sem_alloc(unsigned int value, semid_t semid, sem_t *semp)
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{
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sem_t sem;
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if (value > SEM_VALUE_MAX)
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return (EINVAL);
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if ((sem = malloc(sizeof(struct _sem_st))) == NULL)
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return (ENOSPC);
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sem->usem_magic = USEM_MAGIC;
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pthread_lockinit(&sem->usem_interlock);
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PTQ_INIT(&sem->usem_waiters);
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sem->usem_count = value;
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sem->usem_semid = semid;
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*semp = sem;
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return (0);
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}
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int
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sem_init(sem_t *sem, int pshared, unsigned int value)
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{
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semid_t semid;
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int error;
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semid = USEM_USER;
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if (pshared && _ksem_init(value, &semid) == -1)
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return (-1);
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if ((error = sem_alloc(value, semid, sem)) != 0) {
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if (semid != USEM_USER)
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_ksem_destroy(semid);
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errno = error;
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return (-1);
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}
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return (0);
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}
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int
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sem_destroy(sem_t *sem)
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{
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pthread_t self;
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#ifdef ERRORCHECK
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if (sem == NULL || *sem == NULL || (*sem)->usem_magic != USEM_MAGIC) {
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errno = EINVAL;
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return (-1);
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}
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#endif
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if ((*sem)->usem_semid != USEM_USER) {
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if (_ksem_destroy((*sem)->usem_semid))
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return (-1);
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} else {
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self = pthread__self();
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pthread_spinlock(self, &(*sem)->usem_interlock);
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if (!PTQ_EMPTY(&(*sem)->usem_waiters)) {
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pthread_spinunlock(self, &(*sem)->usem_interlock);
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errno = EBUSY;
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return (-1);
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}
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pthread_spinunlock(self, &(*sem)->usem_interlock);
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}
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sem_free(*sem);
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return (0);
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}
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sem_t *
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sem_open(const char *name, int oflag, ...)
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{
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sem_t *sem, s;
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semid_t semid;
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mode_t mode;
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unsigned int value;
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int error;
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va_list ap;
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mode = 0;
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value = 0;
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if (oflag & O_CREAT) {
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va_start(ap, oflag);
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mode = va_arg(ap, int);
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value = va_arg(ap, unsigned int);
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va_end(ap);
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}
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/*
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* We can be lazy and let the kernel handle the oflag,
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* we'll just merge duplicate IDs into our list.
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*/
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if (_ksem_open(name, oflag, mode, value, &semid) == -1)
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return (SEM_FAILED);
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/*
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* Search for a duplicate ID, we must return the same sem_t *
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* if we locate one.
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*/
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pthread_mutex_lock(&named_sems_mtx);
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LIST_FOREACH(s, &named_sems, usem_list) {
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if (s->usem_semid == semid) {
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pthread_mutex_unlock(&named_sems_mtx);
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return (s->usem_identity);
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}
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}
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if ((sem = malloc(sizeof(*sem))) == NULL) {
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error = ENOSPC;
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goto bad;
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}
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if ((error = sem_alloc(value, semid, sem)) != 0)
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goto bad;
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LIST_INSERT_HEAD(&named_sems, *sem, usem_list);
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(*sem)->usem_identity = sem;
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pthread_mutex_unlock(&named_sems_mtx);
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return (sem);
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bad:
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pthread_mutex_unlock(&named_sems_mtx);
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_ksem_close(semid);
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if (sem != NULL) {
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if (*sem != NULL)
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sem_free(*sem);
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free(sem);
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}
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errno = error;
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return (SEM_FAILED);
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}
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int
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sem_close(sem_t *sem)
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{
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#ifdef ERRORCHECK
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if (sem == NULL || *sem == NULL || (*sem)->usem_magic != USEM_MAGIC) {
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errno = EINVAL;
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return (-1);
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}
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#endif
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if ((*sem)->usem_semid == USEM_USER) {
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errno = EINVAL;
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return (-1);
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}
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pthread_mutex_lock(&named_sems_mtx);
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if (_ksem_close((*sem)->usem_semid) == -1) {
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pthread_mutex_unlock(&named_sems_mtx);
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return (-1);
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}
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LIST_REMOVE((*sem), usem_list);
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pthread_mutex_unlock(&named_sems_mtx);
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sem_free(*sem);
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free(sem);
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return (0);
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}
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int
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sem_unlink(const char *name)
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{
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return (_ksem_unlink(name));
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}
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int
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sem_wait(sem_t *sem)
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{
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pthread_t self;
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extern int pthread__started;
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struct pthread_queue_t *queue;
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#ifdef ERRORCHECK
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if (sem == NULL || *sem == NULL || (*sem)->usem_magic != USEM_MAGIC) {
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errno = EINVAL;
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return (-1);
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}
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#endif
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self = pthread__self();
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if ((*sem)->usem_semid != USEM_USER) {
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pthread__testcancel(self);
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return (_ksem_wait((*sem)->usem_semid));
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}
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if (pthread__started == 0) {
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sigset_t set, oset;
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sigfillset(&set);
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(void) sigprocmask(SIG_SETMASK, &set, &oset);
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for (;;) {
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if ((*sem)->usem_count > 0) {
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break;
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}
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(void) sigsuspend(&oset);
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}
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(*sem)->usem_count--;
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(void) sigprocmask(SIG_SETMASK, &oset, NULL);
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return 0;
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}
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queue = &(*sem)->usem_waiters;
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pthread_spinlock(self, &(*sem)->usem_interlock);
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for (;;) {
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if (self->pt_cancel) {
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pthread_spinunlock(self, &(*sem)->usem_interlock);
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pthread_exit(PTHREAD_CANCELED);
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}
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if ((*sem)->usem_count > 0)
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break;
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PTQ_INSERT_TAIL(queue, self, pt_sleep);
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self->pt_sleeponq = 1;
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self->pt_sleepobj = queue,
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(void)pthread__park(self, &(*sem)->usem_interlock,
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queue, NULL, 1);
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}
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(*sem)->usem_count--;
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pthread_spinunlock(self, &(*sem)->usem_interlock);
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return (0);
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}
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int
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sem_trywait(sem_t *sem)
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{
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pthread_t self;
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extern int pthread__started;
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#ifdef ERRORCHECK
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if (sem == NULL || *sem == NULL || (*sem)->usem_magic != USEM_MAGIC) {
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errno = EINVAL;
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return (-1);
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}
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#endif
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if ((*sem)->usem_semid != USEM_USER)
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return (_ksem_trywait((*sem)->usem_semid));
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if (pthread__started == 0) {
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sigset_t set, oset;
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int rv = 0;
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sigfillset(&set);
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(void) sigprocmask(SIG_SETMASK, &set, &oset);
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if ((*sem)->usem_count > 0) {
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(*sem)->usem_count--;
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} else {
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errno = EAGAIN;
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rv = -1;
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}
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(void) sigprocmask(SIG_SETMASK, &oset, NULL);
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return rv;
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}
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self = pthread__self();
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pthread_spinlock(self, &(*sem)->usem_interlock);
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if ((*sem)->usem_count == 0) {
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pthread_spinunlock(self, &(*sem)->usem_interlock);
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errno = EAGAIN;
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return (-1);
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}
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(*sem)->usem_count--;
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pthread_spinunlock(self, &(*sem)->usem_interlock);
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return (0);
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}
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int
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sem_post(sem_t *sem)
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{
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pthread_t self, blocked;
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#ifdef ERRORCHECK
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if (sem == NULL || *sem == NULL || (*sem)->usem_magic != USEM_MAGIC) {
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errno = EINVAL;
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return (-1);
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}
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#endif
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if ((*sem)->usem_semid != USEM_USER)
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return (_ksem_post((*sem)->usem_semid));
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self = pthread__self();
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pthread_spinlock(self, &(*sem)->usem_interlock);
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(*sem)->usem_count++;
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blocked = PTQ_FIRST(&(*sem)->usem_waiters);
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if (blocked) {
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PTQ_REMOVE(&(*sem)->usem_waiters, blocked, pt_sleep);
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/* Give the head of the blocked queue another try. */
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pthread__unpark(self, &(*sem)->usem_interlock,
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&(*sem)->usem_waiters, blocked);
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} else
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pthread_spinunlock(self, &(*sem)->usem_interlock);
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return (0);
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}
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int
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sem_getvalue(sem_t * __restrict sem, int * __restrict sval)
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{
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pthread_t self;
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#ifdef ERRORCHECK
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if (sem == NULL || *sem == NULL || (*sem)->usem_magic != USEM_MAGIC) {
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errno = EINVAL;
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return (-1);
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}
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#endif
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if ((*sem)->usem_semid != USEM_USER)
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return (_ksem_getvalue((*sem)->usem_semid, sval));
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self = pthread__self();
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pthread_spinlock(self, &(*sem)->usem_interlock);
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*sval = (int) (*sem)->usem_count;
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pthread_spinunlock(self, &(*sem)->usem_interlock);
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return (0);
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}
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