86 lines
3.0 KiB
C
86 lines
3.0 KiB
C
/****************************************************************************
|
|
* sched/sched/sched_idletask.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 <stdbool.h>
|
|
#include <assert.h>
|
|
|
|
#include <nuttx/init.h>
|
|
#include <nuttx/sched.h>
|
|
|
|
#include "sched/sched.h"
|
|
|
|
/****************************************************************************
|
|
* Public Functions
|
|
****************************************************************************/
|
|
|
|
/****************************************************************************
|
|
* Name: sched_idletask
|
|
*
|
|
* Description:
|
|
* Check if the caller is an IDLE thread. For most implementations of
|
|
* the SYSLOG output semaphore locking is required for mutual exclusion.
|
|
* The idle threads are unable to lock semaphores because they cannot
|
|
* wait. So IDLE thread output is a special case and is treated much as
|
|
* we treat debug output from an interrupt handler.
|
|
*
|
|
* Input Parameters:
|
|
* None
|
|
*
|
|
* Returned Value:
|
|
* true if the calling task is an IDLE thread.
|
|
*
|
|
****************************************************************************/
|
|
|
|
bool sched_idletask(void)
|
|
{
|
|
FAR struct tcb_s *rtcb = this_task();
|
|
|
|
/* If called early in the initialization sequence, the tasks lists may not
|
|
* have been initialized and, in that case, rtcb may be NULL.
|
|
*/
|
|
|
|
DEBUGASSERT(rtcb != NULL || g_nx_initstate < OSINIT_TASKLISTS);
|
|
if (rtcb != NULL)
|
|
{
|
|
/* The IDLE task TCB is distinguishable by a few things:
|
|
*
|
|
* (1) It always lies at the end of the task list,
|
|
* (2) It always has priority zero, and
|
|
* (3) It should have the TCB_FLAG_CPU_LOCKED flag set.
|
|
*
|
|
* In the non-SMP case, the IDLE task will also have PID=0, but that
|
|
* is not a portable test because there are multiple IDLE tasks with
|
|
* different PIDs in the SMP configuration.
|
|
*/
|
|
|
|
return is_idle_task(rtcb);
|
|
}
|
|
|
|
/* We must be on the IDLE thread if we are early in initialization */
|
|
|
|
return true;
|
|
}
|