161 lines
4.8 KiB
C
161 lines
4.8 KiB
C
/****************************************************************************
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* sched/task/task_exit.c
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*
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* SPDX-License-Identifier: Apache-2.0
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*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership. The
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* ASF licenses this file to you under the Apache License, Version 2.0 (the
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* "License"); you may not use this file except in compliance with the
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* License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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* License for the specific language governing permissions and limitations
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* under the License.
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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 <sched.h>
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#include <debug.h>
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#include <nuttx/sched_note.h>
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#include "sched/sched.h"
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#ifdef CONFIG_SMP
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# include "irq/irq.h"
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#endif
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#include "signal/signal.h"
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#include "task/task.h"
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: nxtask_exit
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*
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* Description:
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* This is a part of the logic used to implement _exit(). The full
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* implementation of _exit() is architecture-dependent. The _exit()
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* function also implements the bottom half of exit() and pthread_exit().
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*
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* This function causes the currently running task (i.e., the task at the
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* head of the ready-to-run list) to cease to exist. This function should
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* never be called from normal user code, but only from the architecture-
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* specific implementation of exit.
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*
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* Threads/tasks could also be terminated via pthread_cancel,
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* task_delete(), and task_restart(). In the last two cases, the
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* task will be terminated as though exit() were called.
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*
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* Input Parameters:
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* None
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*
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* Returned Value:
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* OK on success; or ERROR on failure
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*
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* Assumptions:
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* Executing within a critical section established by the caller.
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*
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****************************************************************************/
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int nxtask_exit(void)
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{
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FAR struct tcb_s *dtcb;
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FAR struct tcb_s *rtcb;
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int ret;
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#ifdef CONFIG_SMP
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/* Avoid using this_task() because it may assume a state that is not
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* appropriate for an exiting task.
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*/
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dtcb = current_task(this_cpu());
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#else
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dtcb = this_task();
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#endif
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sinfo("%s pid=%d,TCB=%p\n", get_task_name(dtcb),
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dtcb->pid, dtcb);
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/* Update scheduler parameters */
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nxsched_suspend_scheduler(dtcb);
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/* Remove the TCB of the current task from the ready-to-run list. A
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* context switch will definitely be necessary -- that must be done
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* by the architecture-specific logic.
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*
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* nxsched_remove_readytorun will mark the task at the head of the
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* ready-to-run with state == TSTATE_TASK_RUNNING
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*/
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nxsched_remove_self(dtcb);
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/* Get the new task at the head of the ready to run list */
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#ifdef CONFIG_SMP
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rtcb = current_task(this_cpu());
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#else
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rtcb = this_task();
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#endif
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/* NOTE: nxsched_resume_scheduler() was moved to up_exit()
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* because the global IRQ control for SMP should be deferred until
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* context switching, otherwise, the context switching would be done
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* without a critical section
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*/
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/* We are now in a bad state -- the head of the ready to run task list
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* does not correspond to the thread that is running. Disabling pre-
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* emption on this TCB and marking the new ready-to-run task as not
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* running.
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*
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* We disable pre-emption here by directly incrementing the lockcount
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* (vs. calling sched_lock()).
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*/
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rtcb->lockcount++;
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rtcb->task_state = TSTATE_TASK_READYTORUN;
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#ifdef CONFIG_SMP
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/* NOTE:
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* During nxtask_terminate(), enter_critical_section() will be called
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* to deallocate tcb. However, this would acquire g_cpu_irqlock if
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* rtcb->irqcount = 0, event though we are in critical section.
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* To prevent from acquiring, increment rtcb->irqcount here.
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*/
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rtcb->irqcount++;
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#endif
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dtcb->task_state = TSTATE_TASK_INACTIVE;
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sched_note_stop(dtcb);
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ret = nxsched_release_tcb(dtcb, dtcb->flags & TCB_FLAG_TTYPE_MASK);
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#ifdef CONFIG_SMP
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rtcb->irqcount--;
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#endif
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rtcb->task_state = TSTATE_TASK_RUNNING;
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/* Decrement the lockcount on rctb. */
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rtcb->lockcount--;
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return ret;
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}
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