327 lines
9.5 KiB
C
327 lines
9.5 KiB
C
/****************************************************************************
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* sched/pthread/pthread_mutex.c
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*
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* Copyright (C) 2017 Gregory Nutt. All rights reserved.
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* Author: Gregory Nutt <gnutt@nuttx.org>
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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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*
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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
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* the documentation and/or other materials provided with the
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* distribution.
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* 3. Neither the name NuttX nor the names of its contributors may be
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* 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 THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
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* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
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* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
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* 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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/****************************************************************************
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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 <sched.h>
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#include <assert.h>
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#include <errno.h>
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#include <nuttx/irq.h>
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#include <nuttx/sched.h>
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#include <nuttx/semaphore.h>
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#include "sched/sched.h"
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#include "pthread/pthread.h"
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/****************************************************************************
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* Private Functions
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****************************************************************************/
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/****************************************************************************
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* Name: pthread_mutex_add
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*
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* Description:
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* Add the mutex to the list of mutexes held by this pthread.
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*
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* Input Parameters:
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* mutex - The mutex to be locked
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*
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* Returned Value:
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* None
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*
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****************************************************************************/
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static void pthread_mutex_add(FAR struct pthread_mutex_s *mutex)
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{
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FAR struct tcb_s *rtcb = this_task();
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DEBUGASSERT(mutex->flink == NULL);
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/* Check if this is a pthread. The main thread may also lock and unlock
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* mutexes. The main thread, however, does not participate in the mutex
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* consistency logic. Presumably, when the main thread exits, all of the
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* child pthreads will also terminate.
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*
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* REVISIT: NuttX does not support that behavior at present; child pthreads
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* will persist after the main thread exits.
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*/
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if ((rtcb->flags & TCB_FLAG_TTYPE_MASK) == TCB_FLAG_TTYPE_PTHREAD)
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{
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FAR struct pthread_tcb_s *ptcb = (FAR struct pthread_tcb_s *)rtcb;
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irqstate_t flags;
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/* Add the mutex to the list of mutexes held by this pthread */
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flags = enter_critical_section();
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mutex->flink = ptcb->mhead;
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ptcb->mhead = mutex;
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leave_critical_section(flags);
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}
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}
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/****************************************************************************
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* Name: pthread_mutex_remove
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*
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* Description:
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* Remove the mutex to the list of mutexes held by this pthread.
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*
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* Input Parameters:
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* mutex - The mutex to be locked
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*
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* Returned Value:
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* None
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*
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****************************************************************************/
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static void pthread_mutex_remove(FAR struct pthread_mutex_s *mutex)
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{
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FAR struct tcb_s *rtcb = this_task();
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/* Check if this is a pthread. The main thread may also lock and unlock
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* mutexes. The main thread, however, does not participate in the mutex
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* consistency logic.
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*/
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if ((rtcb->flags & TCB_FLAG_TTYPE_MASK) == TCB_FLAG_TTYPE_PTHREAD)
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{
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FAR struct pthread_tcb_s *ptcb = (FAR struct pthread_tcb_s *)rtcb;
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FAR struct pthread_mutex_s *curr;
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FAR struct pthread_mutex_s *prev;
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irqstate_t flags;
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flags = enter_critical_section();
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/* Remove the mutex from the list of mutexes held by this task */
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for (prev = NULL, curr = ptcb->mhead;
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curr != NULL && curr != mutex;
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prev = curr, curr = curr->flink);
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DEBUGASSERT(curr == mutex);
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/* Remove the mutex from the list. prev == NULL means that the mutex
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* to be removed is at the head of the list.
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*/
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if (prev == NULL)
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{
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ptcb->mhead = mutex->flink;
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}
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else
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{
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prev->flink = mutex->flink;
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}
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mutex->flink = NULL;
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leave_critical_section(flags);
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}
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}
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: pthread_mutex_take
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*
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* Description:
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* Take the pthread_mutex, waiting if necessary. If successful, add the
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* mutex to the list of mutexes held by this thread.
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*
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* Input Parameters:
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* mutex - The mutex to be locked
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* intr - false: ignore EINTR errors when locking; true treat EINTR as
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* other errors by returning the errno value
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*
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* Returned Value:
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* 0 on success or an errno value on failure.
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*
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****************************************************************************/
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int pthread_mutex_take(FAR struct pthread_mutex_s *mutex, FAR const struct timespec *abs_timeout, bool intr)
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{
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int ret = EINVAL;
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/* Verify input parameters */
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DEBUGASSERT(mutex != NULL);
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if (mutex != NULL)
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{
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/* Make sure that no unexpected context switches occur */
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sched_lock();
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/* Error out if the mutex is already in an inconsistent state. */
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if ((mutex->flags & _PTHREAD_MFLAGS_INCONSISTENT) != 0)
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{
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ret = EOWNERDEAD;
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}
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else
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{
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/* Take semaphore underlying the mutex. pthread_sem_take
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* returns zero on success and a positive errno value on failure.
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*/
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ret = pthread_sem_take(&mutex->sem, abs_timeout, intr);
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if (ret == OK)
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{
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/* Check if the holder of the mutex has terminated without
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* releasing. In that case, the state of the mutex is
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* inconsistent and we return EOWNERDEAD.
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*/
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if ((mutex->flags & _PTHREAD_MFLAGS_INCONSISTENT) != 0)
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{
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ret = EOWNERDEAD;
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}
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/* Add the mutex to the list of mutexes held by this task */
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else
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{
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pthread_mutex_add(mutex);
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}
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}
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}
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sched_unlock();
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}
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return ret;
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}
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/****************************************************************************
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* Name: pthread_mutex_trytake
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*
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* Description:
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* Try to take the pthread_mutex without waiting. If successful, add the
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* mutex to the list of mutexes held by this thread.
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*
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* Input Parameters:
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* mutex - The mutex to be locked
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* intr - false: ignore EINTR errors when locking; true treat EINTR as
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* other errors by returning the errno value
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*
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* Returned Value:
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* 0 on success or an errno value on failure.
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*
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****************************************************************************/
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int pthread_mutex_trytake(FAR struct pthread_mutex_s *mutex)
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{
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int ret = EINVAL;
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/* Verify input parameters */
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DEBUGASSERT(mutex != NULL);
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if (mutex != NULL)
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{
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/* Make sure that no unexpected context switches occur */
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sched_lock();
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/* Error out if the mutex is already in an inconsistent state. */
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if ((mutex->flags & _PTHREAD_MFLAGS_INCONSISTENT) != 0)
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{
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ret = EOWNERDEAD;
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}
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else
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{
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/* Try to take the semaphore underlying the mutex */
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ret = nxsem_trywait(&mutex->sem);
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if (ret < 0)
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{
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ret = -ret;
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}
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else
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{
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/* Add the mutex to the list of mutexes held by this task */
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pthread_mutex_add(mutex);
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}
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}
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sched_unlock();
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}
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return ret;
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}
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/****************************************************************************
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* Name: pthread_mutex_give
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*
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* Description:
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* Take the pthread_mutex and, if successful, add the mutex to the ist of
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* mutexes held by this thread.
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*
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* Input Parameters:
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* mutex - The mutex to be unlocked
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*
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* Returned Value:
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* 0 on success or an errno value on failure.
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*
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****************************************************************************/
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int pthread_mutex_give(FAR struct pthread_mutex_s *mutex)
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{
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int ret = EINVAL;
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/* Verify input parameters */
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DEBUGASSERT(mutex != NULL);
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if (mutex != NULL)
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{
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/* Remove the mutex from the list of mutexes held by this task */
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pthread_mutex_remove(mutex);
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/* Now release the underlying semaphore */
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ret = pthread_sem_give(&mutex->sem);
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}
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return ret;
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}
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