215 lines
7.0 KiB
C
215 lines
7.0 KiB
C
/****************************************************************************
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* sched/task/task_delete.c
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*
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* Copyright (C) 2007-2009, 2011-2013, 2016-2017 Gregory Nutt. All rights
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* reserved.
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* Author: Gregory Nutt <gnutt@nuttx.org>
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* distribution.
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* 3. Neither the name NuttX nor the names of its contributors may be
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* used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
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* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
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* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
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* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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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 *)sched_gettcb(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 to see if this task has the non-cancelable bit set in its
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* flags. Suppress context changes for a bit so that the flags are stable.
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* (the flags should not change in interrupt handling).
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*/
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sched_lock();
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if ((dtcb->flags & TCB_FLAG_NONCANCELABLE) != 0)
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{
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/* Then we cannot cancel the thread now. Here is how this is
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* supposed to work:
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*
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* "When cancellability is disabled, all cancels are held pending
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* in the target thread until the thread changes the cancellability.
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* When cancellability is deferred, all cancels are held pending in
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* the target thread until the thread changes the cancellability,
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* calls a function which is a cancellation point or calls
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* pthread_testcancel(), thus creating a cancellation point. When
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* cancellability is asynchronous, all cancels are acted upon
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* immediately, interrupting the thread with its processing."
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*/
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dtcb->flags |= TCB_FLAG_CANCEL_PENDING;
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sched_unlock();
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return OK;
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}
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#ifdef CONFIG_CANCELLATION_POINTS
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/* Check if this task supports deferred cancellation */
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if ((dtcb->flags & TCB_FLAG_CANCEL_DEFERRED) != 0)
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{
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/* Then we cannot cancel the task asynchronously. Mark the
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* cancellation as pending.
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*/
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dtcb->flags |= TCB_FLAG_CANCEL_PENDING;
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/* If the task is waiting at a cancellation point, then notify of the
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* cancellation thereby waking the task up with an ECANCELED error.
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*/
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if (dtcb->cpcount > 0)
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{
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nxnotify_cancellation(dtcb);
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}
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sched_unlock();
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return OK;
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}
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#endif
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/* Check if the task to delete is the calling task */
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sched_unlock();
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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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/* 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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