5c80b94820
Since the kernel side should call nxsem_xxx instead and remove the unused inclusion
214 lines
6.9 KiB
C
214 lines
6.9 KiB
C
/****************************************************************************
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* sched/pthread/pthread_mutextrylock.c
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*
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* Copyright (C) 2007-2009, 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 <unistd.h>
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#include <pthread.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 <debug.h>
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#include "pthread/pthread.h"
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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_trylock
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*
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* Description:
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* The function pthread_mutex_trylock() is identical to pthread_mutex_lock()
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* except that if the mutex object referenced by mutex is currently locked
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* (by any thread, including the current thread), the call returns
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* immediately with the errno EBUSY.
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*
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* If a signal is delivered to a thread waiting for a mutex, upon return
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* from the signal handler the thread resumes waiting for the mutex as if
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* it was not interrupted.
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*
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* Input Parameters:
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* mutex - A reference to the mutex to be locked.
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*
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* Returned Value:
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* 0 on success or an errno value on failure. Note that the errno EINTR
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* is never returned by pthread_mutex_trylock().
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*
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* Assumptions:
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*
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* POSIX Compatibility:
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* - This implementation does not return EAGAIN when the mutex could not be
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* acquired because the maximum number of recursive locks for mutex has
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* been exceeded.
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*
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****************************************************************************/
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int pthread_mutex_trylock(FAR pthread_mutex_t *mutex)
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{
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int status;
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int ret = EINVAL;
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sinfo("mutex=0x%p\n", mutex);
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DEBUGASSERT(mutex != NULL);
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if (mutex != NULL)
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{
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int mypid = (int)getpid();
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/* Make sure the semaphore is stable while we make the following
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* checks. This all needs to be one atomic action.
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*/
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sched_lock();
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/* Try to get the semaphore. */
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status = pthread_mutex_trytake(mutex);
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if (status == OK)
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{
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/* If we successfully obtained the semaphore, then indicate
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* that we own it.
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*/
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mutex->pid = mypid;
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#ifdef CONFIG_PTHREAD_MUTEX_TYPES
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if (mutex->type == PTHREAD_MUTEX_RECURSIVE)
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{
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mutex->nlocks = 1;
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}
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#endif
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ret = OK;
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}
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/* pthread_mutex_trytake failed. Did it fail because the semaphore
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* was not avaialable?
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*/
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else if (status == EAGAIN)
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{
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#ifdef CONFIG_PTHREAD_MUTEX_TYPES
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/* Check if recursive mutex was locked by the calling thread. */
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if (mutex->type == PTHREAD_MUTEX_RECURSIVE && mutex->pid == mypid)
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{
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/* Increment the number of locks held and return successfully. */
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if (mutex->nlocks < INT16_MAX)
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{
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mutex->nlocks++;
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ret = OK;
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}
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else
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{
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ret = EOVERFLOW;
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}
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}
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else
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#endif
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#ifndef CONFIG_PTHREAD_MUTEX_UNSAFE
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/* The calling thread does not hold the semaphore. The correct
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* behavior for the 'robust' mutex is to verify that the holder of
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* the mutex is still valid. This is protection from the case
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* where the holder of the mutex has exitted without unlocking it.
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*/
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#ifdef CONFIG_PTHREAD_MUTEX_BOTH
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#ifdef CONFIG_PTHREAD_MUTEX_TYPES
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/* Check if this NORMAL mutex is robust */
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if (mutex->pid > 0 &&
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((mutex->flags & _PTHREAD_MFLAGS_ROBUST) != 0 ||
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mutex->type != PTHREAD_MUTEX_NORMAL) &&
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sched_gettcb(mutex->pid) == NULL)
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#else /* CONFIG_PTHREAD_MUTEX_TYPES */
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/* Check if this NORMAL mutex is robust */
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if (mutex->pid > 0 &&
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(mutex->flags & _PTHREAD_MFLAGS_ROBUST) != 0 &&
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sched_gettcb(mutex->pid) == NULL)
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#endif /* CONFIG_PTHREAD_MUTEX_TYPES */
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#else /* CONFIG_PTHREAD_MUTEX_ROBUST */
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/* This mutex is always robust, whatever type it is. */
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if (mutex->pid > 0 && sched_gettcb(mutex->pid) == NULL)
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#endif
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{
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DEBUGASSERT(mutex->pid != 0); /* < 0: available, >0 owned, ==0 error */
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DEBUGASSERT((mutex->flags & _PTHREAD_MFLAGS_INCONSISTENT) != 0);
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/* A thread holds the mutex, but there is no such thread.
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* POSIX requires that the 'robust' mutex return EOWNERDEAD
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* in this case. It is then the caller's responsibility to
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* call pthread_mutx_consistent() fo fix the mutex.
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*/
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mutex->flags |= _PTHREAD_MFLAGS_INCONSISTENT;
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ret = EOWNERDEAD;
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}
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/* The mutex is locked by another, active thread */
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else
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#endif /* CONFIG_PTHREAD_MUTEX_UNSAFE */
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{
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ret = EBUSY;
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}
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}
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/* Some other, unhandled error occurred */
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else
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{
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ret = status;
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}
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sched_unlock();
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}
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sinfo("Returning %d\n", ret);
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return ret;
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}
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