154 lines
4.6 KiB
C
154 lines
4.6 KiB
C
/****************************************************************************
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* sched/task/task_delete.c
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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 <stdlib.h>
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#include <errno.h>
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#include <nuttx/sched.h>
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#include "sched/sched.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: task_delete
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*
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* Description:
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* This function causes a specified task to cease to exist. Its stack and
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* TCB will be deallocated. This function is the companion to
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* task_create(). This is the version of the function exposed to the
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* user; it is simply a wrapper around the internal, nxtask_terminate
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* function.
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*
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* The logic in this function only deletes non-running tasks. If the
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* 'pid' parameter refers to the currently running task, then processing
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* is redirected to exit(). This can only happen if a task calls
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* task_delete()in order to delete itself.
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*
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* This function obeys the semantics of pthread cancellation: task
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* deletion is deferred if cancellation is disabled or if deferred
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* cancellation is supported (with cancellation points enabled).
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*
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* Input Parameters:
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* pid - The task ID of the task to delete. A pid of zero
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* signifies the calling task.
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*
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* Returned Value:
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* OK on success; or ERROR on failure with the errno variable set
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* appropriately.
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*
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****************************************************************************/
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int task_delete(pid_t pid)
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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 errcode;
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int ret;
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/* Check if the task to delete is the calling task: PID=0 means to delete
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* the calling task. In this case, task_delete() is much like exit()
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* except that it obeys the cancellation semantics.
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*/
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rtcb = this_task();
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if (pid == 0)
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{
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pid = rtcb->pid;
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}
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/* Get the TCB of the task to be deleted */
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dtcb = (FAR struct tcb_s *)nxsched_get_tcb(pid);
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if (dtcb == NULL)
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{
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/* The pid does not correspond to any known thread. The task
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* has probably already exited.
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*/
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errcode = ESRCH;
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goto errout;
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}
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/* Only tasks and kernel threads can be deleted with this interface
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* (The semantics of the call should be sufficient to prohibit this).
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*/
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DEBUGASSERT((dtcb->flags & TCB_FLAG_TTYPE_MASK) != TCB_FLAG_TTYPE_PTHREAD);
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/* Non-privileged tasks and pthreads may not delete privileged kernel
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* threads.
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*
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* REVISIT: We will need to look at this again in the future if/when
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* permissions are supported and a user task might also be privileged.
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*/
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if (((rtcb->flags & TCB_FLAG_TTYPE_MASK) != TCB_FLAG_TTYPE_KERNEL) &&
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((dtcb->flags & TCB_FLAG_TTYPE_MASK) == TCB_FLAG_TTYPE_KERNEL))
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{
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errcode = EACCES;
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goto errout;
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}
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/* Check if the task to delete is the calling task */
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if (pid == rtcb->pid)
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{
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/* If it is, then what we really wanted to do was exit. Note that we
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* don't bother to unlock the TCB since it will be going away.
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*/
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exit(EXIT_SUCCESS);
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}
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/* Notify the target if the non-cancelable or deferred cancellation set */
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if (nxnotify_cancellation(dtcb))
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{
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return OK;
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}
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/* Otherwise, perform the asynchronous cancellation, letting
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* nxtask_terminate() do all of the heavy lifting.
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*/
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ret = nxtask_terminate(pid, false);
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if (ret < 0)
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{
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errcode = -ret;
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goto errout;
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}
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return OK;
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errout:
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set_errno(errcode);
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return ERROR;
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}
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