incubator-nuttx/sched/mqueue/mq_waitirq.c

113 lines
3.5 KiB
C

/****************************************************************************
* sched/mqueue/mq_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 <errno.h>
#include <nuttx/irq.h>
#include <nuttx/arch.h>
#include <nuttx/mqueue.h>
#include "mqueue/mqueue.h"
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: nxmq_wait_irq
*
* Description:
* This function is called when a signal or a timeout is received by a
* task that is waiting on a message queue -- either for a queue to
* becoming not full (on mq_send and friends) or not empty (on mq_receive
* and friends).
*
* Input Parameters:
* wtcb - A pointer to the TCB of the task that is waiting on a message
* queue, but has received a signal instead.
*
* Returned Value:
* None
*
* Assumptions:
*
****************************************************************************/
void nxmq_wait_irq(FAR struct tcb_s *wtcb, int errcode)
{
FAR struct mqueue_inode_s *msgq;
irqstate_t flags;
/* Disable interrupts. This is necessary because an interrupt handler may
* attempt to send a message 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. NOTE: The operations within the if
* are safe because interrupts are always disabled with the msgwaitq,
* nwaitnotempty, and nwaitnotfull fields are modified.
*/
if (wtcb->task_state == TSTATE_WAIT_MQNOTEMPTY ||
wtcb->task_state == TSTATE_WAIT_MQNOTFULL)
{
/* Get the message queue associated with the waiter from the TCB */
msgq = wtcb->msgwaitq;
DEBUGASSERT(msgq);
wtcb->msgwaitq = NULL;
/* Decrement the count of waiters and cancel the wait */
if (wtcb->task_state == TSTATE_WAIT_MQNOTEMPTY)
{
DEBUGASSERT(msgq->nwaitnotempty > 0);
msgq->nwaitnotempty--;
}
else
{
DEBUGASSERT(msgq->nwaitnotfull > 0);
msgq->nwaitnotfull--;
}
/* Mark the error value for the thread. */
wtcb->errcode = errcode;
/* Restart the task. */
up_unblock_task(wtcb);
}
/* Interrupts may now be enabled. */
leave_critical_section(flags);
}