nuttx/sched/semaphore/sem_waitirq.c

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/****************************************************************************
This change renames all internal, private NuttX signal-related functions to use the prefix nxsig_ so that they cannot be confused with application interfaces that begin, primarily, with sig_ This is analogous to similar renaming that was done previously for semaphores. Squashed commit of the following: sched/signal: Fix a few compile warnings introduced by naming changes. sched/signal: Rename all private, internal signl functions to use the nxsig_ prefix. sched/signal: Rename sig_removependingsignal, sig_unmaskpendingsignal, and sig_mqnotempty to nxsig_remove_pendingsignal, nxsig_unmask_pendingsignal, and nxsig_mqnotempty to make it clear that these are OS internal interfaces. sched/signal: Rename sig_findaction and sig_lowest to nxsig_find_action and nxsig_lowest to make it clear that these are OS internal interfaces. sched/signal: Rename sig_allocatepingsigaction and sig_deliver to nxsig_alloc_pendingsigaction and nxsig_deliver to make it clear that these are OS internal interfaces. sched/signal: Rename sig_cleanup, sig_release, sig_releasependingaction, and sig_releasependingsignal to nxsig_cleanup, nxsig_release, nxsig_release_pendingaction, and nxsig_release_pendingsignal to make it clear that these are OS internal interfaces. sched/signal: Rename sig_tcbdispatch and sig_dispatch to nxsig_tcbdispatch and nxsig_dispatch to make it clear that these are OS internal interfaces. sched/signal: Rename sig_releaseaction and sig_pendingset to nxsig_release_action and nxsig_pendingset to make it clear that these are OS internal interfaces. sched/signal: Rename sig_initialize and sig_allocateactionblock to nxsig_initialize and nxsig_alloc_actionblock to make it clear that these are OS internal interfaces.
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* sched/semaphore/sem_waitirq.c
*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership. The
* ASF licenses this file to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance with the
* License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations
* under the License.
*
****************************************************************************/
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/config.h>
#include <sched.h>
#include <assert.h>
#include <errno.h>
#include <nuttx/irq.h>
#include <nuttx/arch.h>
#include "semaphore/semaphore.h"
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: nxsem_wait_irq
*
* Description:
* This function is called when either:
*
* 1. A signal is received by a task that is waiting on a semaphore.
* According to the POSIX spec, "...the calling thread shall not return
* from the call to [nxsem_wait] until it either locks the semaphore or
* the call is interrupted by a signal."
* 2. From logic associated with sem_timedwait(). This function is called
* when the timeout elapses without receiving the semaphore.
*
* Input Parameters:
* wtcb - A pointer to the TCB of the task that is waiting on a
* semphaphore, but has received a signal or timeout instead.
* errcode - EINTR if the semaphore wait was awakened by a signal;
* ETIMEDOUT if awakened by a timeout
*
* Returned Value:
* None
*
* Assumptions:
*
****************************************************************************/
void nxsem_wait_irq(FAR struct tcb_s *wtcb, int errcode)
{
irqstate_t flags;
/* Disable interrupts. This is necessary (unfortunately) because an
* interrupt handler may attempt to post the semaphore while we are
* doing this.
*/
flags = enter_critical_section();
/* It is possible that an interrupt/context switch beat us to the punch
* and already changed the task's state.
*/
if (wtcb->task_state == TSTATE_WAIT_SEM)
{
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FAR sem_t *sem = wtcb->waitobj;
DEBUGASSERT(sem != NULL && sem->semcount < 0);
/* Restore the correct priority of all threads that hold references
* to this semaphore.
*/
nxsem_canceled(wtcb, sem);
/* And increment the count on the semaphore. This releases the count
* that was taken by sem_post(). This count decremented the semaphore
* count to negative and caused the thread to be blocked in the first
* place.
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*/
sem->semcount++;
/* Mark the errno value for the thread. */
wtcb->errcode = errcode;
/* Restart the task. */
up_unblock_task(wtcb);
}
/* Interrupts may now be enabled. */
leave_critical_section(flags);
}