212 lines
6.9 KiB
C
212 lines
6.9 KiB
C
/****************************************************************************
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* sched/semaphore/sem_clockwait.c
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*
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* SPDX-License-Identifier: Apache-2.0
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*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership. The
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* ASF licenses this file to you under the Apache License, Version 2.0 (the
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* "License"); you may not use this file except in compliance with the
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* License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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* License for the specific language governing permissions and limitations
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* under the License.
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*
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****************************************************************************/
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/****************************************************************************
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* Included Files
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****************************************************************************/
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#include <nuttx/config.h>
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#include <stdint.h>
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#include <unistd.h>
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#include <time.h>
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#include <assert.h>
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#include <errno.h>
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#include <debug.h>
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#include <nuttx/irq.h>
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#include <nuttx/arch.h>
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#include <nuttx/wdog.h>
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#include "sched/sched.h"
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#include "clock/clock.h"
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#include "semaphore/semaphore.h"
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: nxsem_clockwait
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*
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* Description:
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* This function will lock the semaphore referenced by sem as in the
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* sem_wait() function. However, if the semaphore cannot be locked without
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* waiting for another process or thread to unlock the semaphore by
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* performing a sem_post() function, this wait will be terminated when the
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* specified timeout expires.
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*
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* The timeout will expire when the absolute time specified by abstime
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* passes, as measured by the clock on which timeouts are based (that is,
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* when the value of that clock equals or exceeds abstime), or if the
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* absolute time specified by abstime has already been passed at the
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* time of the call.
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*
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* This is an internal OS interface. It is functionally equivalent to
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* sem_wait except that:
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*
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* - It is not a cancellation point, and
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* - It does not modify the errno value.
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*
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* Input Parameters:
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* sem - Semaphore object
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* clockid - The timing source to use in the conversion
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* abstime - The absolute time to wait until a timeout is declared.
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*
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* Returned Value:
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* This is an internal OS interface and should not be used by applications.
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* It follows the NuttX internal error return policy: Zero (OK) is
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* returned on success. A negated errno value is returned on failure.
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* That may be one of:
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*
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* EINVAL The sem argument does not refer to a valid semaphore. Or the
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* thread would have blocked, and the abstime parameter specified
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* a nanoseconds field value less than zero or greater than or
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* equal to 1000 million.
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* ETIMEDOUT The semaphore could not be locked before the specified timeout
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* expired.
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* EDEADLK A deadlock condition was detected.
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* EINTR A signal interrupted this function.
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*
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****************************************************************************/
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int nxsem_clockwait(FAR sem_t *sem, clockid_t clockid,
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FAR const struct timespec *abstime)
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{
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FAR struct tcb_s *rtcb = this_task();
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irqstate_t flags;
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sclock_t ticks;
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int ret = ERROR;
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DEBUGASSERT(sem != NULL && abstime != NULL);
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DEBUGASSERT(up_interrupt_context() == false);
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/* We will disable interrupts until we have completed the semaphore
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* wait. We need to do this (as opposed to just disabling pre-emption)
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* because there could be interrupt handlers that are asynchronously
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* posting semaphores and to prevent race conditions with watchdog
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* timeout. This is not too bad because interrupts will be re-
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* enabled while we are blocked waiting for the semaphore.
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*/
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flags = enter_critical_section();
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/* Try to take the semaphore without waiting. */
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ret = nxsem_trywait(sem);
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if (ret == OK)
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{
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/* We got it! */
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goto out;
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}
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/* We will have to wait for the semaphore. Make sure that we were provided
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* with a valid timeout.
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*/
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#ifdef CONFIG_DEBUG_FEATURES
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if (abstime->tv_nsec < 0 || abstime->tv_nsec >= 1000000000)
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{
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ret = -EINVAL;
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goto out;
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}
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#endif
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/* Convert the timespec to clock ticks. We must have interrupts
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* disabled here so that this time stays valid until the wait begins.
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*
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* clock_abstime2ticks() returns zero on success or a POSITIVE errno
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* value on failure.
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*/
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clock_abstime2ticks(clockid, abstime, &ticks);
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/* If the time has already expired return immediately. */
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if (ticks <= 0)
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{
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ret = -ETIMEDOUT;
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goto out;
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}
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/* Start the watchdog */
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wd_start(&rtcb->waitdog, ticks, nxsem_timeout, nxsched_gettid());
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/* Now perform the blocking wait. If nxsem_wait() fails, the
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* negated errno value will be returned below.
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*/
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ret = nxsem_wait(sem);
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/* Stop the watchdog timer */
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wd_cancel(&rtcb->waitdog);
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/* We can now restore interrupts and delete the watchdog */
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out:
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leave_critical_section(flags);
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return ret;
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}
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/****************************************************************************
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* Name: nxsem_clockwait_uninterruptible
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*
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* Description:
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* This function is wrapped version of nxsem_clockwait(), which is
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* uninterruptible and convenient for use.
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*
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* Input Parameters:
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* sem - Semaphore object
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* clockid - The timing source to use in the conversion
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* abstime - The absolute time to wait until a timeout is declared.
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*
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* Returned Value:
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* EINVAL The sem argument does not refer to a valid semaphore. Or the
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* thread would have blocked, and the abstime parameter specified
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* a nanoseconds field value less than zero or greater than or
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* equal to 1000 million.
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* ETIMEDOUT The semaphore could not be locked before the specified timeout
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* expired.
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* EDEADLK A deadlock condition was detected.
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* ECANCELED May be returned if the thread is canceled while waiting.
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*
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****************************************************************************/
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int nxsem_clockwait_uninterruptible(FAR sem_t *sem, clockid_t clockid,
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FAR const struct timespec *abstime)
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{
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int ret;
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do
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{
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/* Take the semaphore (perhaps waiting) */
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ret = nxsem_clockwait(sem, clockid, abstime);
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}
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while (ret == -EINTR);
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return ret;
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}
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