eb344d7260
This was a consequence of the recent robust mutex changes. If robust mutexes are selected, then each mutex that a thread takes is retained in a list in threads TCB. If the thread exits and that list is not empty, then we know that the thread exitted while holding mutexes. And, in that case, each will be marked as inconsistent and the any waiter for the thread is awakened. For the case of pthread_mutex_trywait(), the mutex was not being added to the list! while not usually a fatal error, this was caught by an assertion when pthread_mutex_unlock() was called: It tried to remove the mutex from the TCB list and it was not there when, of course, it shoule be. The fix was to add pthread_mutex_trytake() which does sem_trywait() and if successful, does correctly add the mutext to the TCB list. This should eliminated the assertion.
284 lines
8.0 KiB
C
284 lines
8.0 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 "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 thread.
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*
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* Parameters:
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* mutex - The mux to be locked
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*
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* Return 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 pthread_tcb_s *rtcb = (FAR struct pthread_tcb_s *)this_task();
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irqstate_t flags;
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DEBUGASSERT(mutex->flink == NULL);
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/* Add the mutex to the list of mutexes held by this task */
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flags = enter_critical_section();
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mutex->flink = rtcb->mhead;
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rtcb->mhead = mutex;
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leave_critical_section(flags);
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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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* Parameters:
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* mutex - The mux to be locked
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* intr - false: ignore EINTR errors when locking; true tread EINTR as
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* other errors by returning the errno value
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*
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* Return 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, 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 */
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ret = pthread_takesemaphore(&mutex->sem, intr);
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if (ret < OK)
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{
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ret = get_errno();
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}
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else
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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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* Parameters:
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* mutex - The mux to be locked
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* intr - false: ignore EINTR errors when locking; true tread EINTR as
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* other errors by returning the errno value
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*
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* Return 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 = sem_trywait(&mutex->sem);
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if (ret < OK)
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{
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ret = get_errno();
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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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* Parameters:
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* mutex - The mux to be unlocked
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*
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* Return 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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FAR struct pthread_mutex_s *curr;
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FAR struct pthread_mutex_s *prev;
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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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FAR struct pthread_tcb_s *rtcb = (FAR struct pthread_tcb_s *)this_task();
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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 = rtcb->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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rtcb->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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/* Now release the underlying semaphore */
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ret = pthread_givesemaphore(&mutex->sem);
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}
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return ret;
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}
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