119 lines
3.7 KiB
C
119 lines
3.7 KiB
C
/****************************************************************************
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* sched/semaphore/sem_protect.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 <stdbool.h>
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#include <errno.h>
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#include "sched/sched.h"
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#include "semaphore/semaphore.h"
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#ifdef CONFIG_PRIORITY_PROTECT
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: nxsem_protect_wait
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*
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* Description:
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* This function attempts to lock the protected semaphore, set the
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* holder tcb priority to ceiling priority.
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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 descriptor.
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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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* Possible returned errors:
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*
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* - EINVAL: Invalid attempt to get the semaphore
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*
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****************************************************************************/
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int nxsem_protect_wait(FAR sem_t *sem)
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{
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if ((sem->flags & SEM_PRIO_MASK) == SEM_PRIO_PROTECT)
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{
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FAR struct tcb_s *rtcb = this_task();
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if (rtcb->sched_priority > sem->ceiling)
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{
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return -EINVAL;
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}
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sem->saved = rtcb->sched_priority;
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rtcb->sched_priority = sem->ceiling;
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}
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return OK;
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}
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/****************************************************************************
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* Name: nxsem_protect_post
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*
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* Description:
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* This function attempts to unlock the protected semaphore, restore the
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* holder tcb priority.
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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 descriptor.
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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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* Possible returned errors:
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*
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****************************************************************************/
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void nxsem_protect_post(FAR sem_t *sem)
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{
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if (sem->saved > 0)
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{
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nxsched_set_priority(this_task(), sem->saved);
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sem->saved = 0;
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}
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}
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#endif /* CONFIG_PRIORITY_PROTECT */
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