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