9568600ab1
This commit backs out most of commit b4747286b1. That change was added because sem_wait() would sometimes cause cancellation points inappropriated. But with these recent changes, nxsem_wait() is used instead and it is not a cancellation point.
In the OS, all calls to sem_wait() changed to nxsem_wait(). nxsem_wait() does not return errors via errno so each place where nxsem_wait() is now called must not examine the errno variable.
In all OS functions (not libraries), change sem_wait() to nxsem_wait(). This will prevent the OS from creating bogus cancellation points and from modifying the per-task errno variable.
sched/semaphore: Add the function nxsem_wait(). This is a new internal OS interface. It is functionally equivalent to sem_wait() except that (1) it is not a cancellation point, and (2) it does not set the per-thread errno value on return.
114 lines
3.5 KiB
C
114 lines
3.5 KiB
C
/****************************************************************************
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* nuttx/graphics/nxterm/nxterm_sem.c
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*
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* Copyright (C) 2012, 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 <semaphore.h>
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#include <assert.h>
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#include <errno.h>
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#include "nxterm.h"
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#ifdef CONFIG_DEBUG_FEATURES
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: nxterm_semwait and nxterm_sempost
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*
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* Description:
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* If debug is on, then lower level code may attempt console output while
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* we are doing console output! In this case, we will toss the nested
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* output to avoid deadlocks and infinite loops.
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*
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* Input Parameters:
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* priv - Driver data structure
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*
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* Returned Value:
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*
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*
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****************************************************************************/
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int nxterm_semwait(FAR struct nxterm_state_s *priv)
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{
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pid_t me;
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int ret;
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/* Does I already hold the semaphore */
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me = getpid();
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if (priv->holder != me)
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{
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/* No.. then wait until the thread that does hold it is finished with it */
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ret = nxsem_wait(&priv->exclsem);
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if (ret == OK)
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{
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/* No I hold the semaphore */
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priv->holder = me;
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}
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return ret;
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}
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/* Abort, abort, abort! I have been re-entered */
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return -EBUSY;
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}
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int nxterm_sempost(FAR struct nxterm_state_s *priv)
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{
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pid_t me = getpid();
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/* Make sure that I really hold the semaphore */
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ASSERT(priv->holder == me);
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/* Then let go of it */
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priv->holder = NO_HOLDER;
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return nxsem_post(&priv->exclsem);
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}
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#endif /* CONFIG_DEBUG_FEATURES */
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