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- /****************************************************************************
- * sched/task/task_delete.c
- *
- * Copyright (C) 2007-2009, 2011-2013, 2016-2017 Gregory Nutt. All rights
- * reserved.
- * Author: Gregory Nutt <gnutt@nuttx.org>
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- *
- * 1. Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- * 2. Redistributions in binary form must reproduce the above copyright
- * notice, this list of conditions and the following disclaimer in
- * the documentation and/or other materials provided with the
- * distribution.
- * 3. Neither the name NuttX nor the names of its contributors may be
- * used to endorse or promote products derived from this software
- * without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
- * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
- * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
- * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
- * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
- * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
- * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
- * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
- * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
- * POSSIBILITY OF SUCH DAMAGE.
- *
- ****************************************************************************/
- /****************************************************************************
- * Included Files
- ****************************************************************************/
- #include <nuttx/config.h>
- #include <stdlib.h>
- #include <errno.h>
- #include <nuttx/sched.h>
- #include "sched/sched.h"
- #include "task/task.h"
- /****************************************************************************
- * Public Functions
- ****************************************************************************/
- /****************************************************************************
- * Name: task_delete
- *
- * Description:
- * This function causes a specified task to cease to exist. Its stack and
- * TCB will be deallocated. This function is the companion to
- * task_create(). This is the version of the function exposed to the
- * user; it is simply a wrapper around the internal, nxtask_terminate
- * function.
- *
- * The logic in this function only deletes non-running tasks. If the
- * 'pid' parameter refers to to the currently runing task, then processing
- * is redirected to exit(). This can only happen if a task calls
- * task_delete()in order to delete itself.
- *
- * This function obeys the semantics of pthread cancellation: task
- * deletion is deferred if cancellation is disabled or if deferred
- * cancellation is supported (with cancellation points enabled).
- *
- * Input Parameters:
- * pid - The task ID of the task to delete. A pid of zero
- * signifies the calling task.
- *
- * Returned Value:
- * OK on success; or ERROR on failure with the errno variable set
- * appropriately.
- *
- ****************************************************************************/
- int task_delete(pid_t pid)
- {
- FAR struct tcb_s *dtcb;
- FAR struct tcb_s *rtcb;
- int errcode;
- int ret;
- /* Check if the task to delete is the calling task: PID=0 means to delete
- * the calling task. In this case, task_delete() is much like exit()
- * except that it obeys the cancellation semantics.
- */
- rtcb = this_task();
- if (pid == 0)
- {
- pid = rtcb->pid;
- }
- /* Get the TCB of the task to be deleted */
- dtcb = (FAR struct tcb_s *)sched_gettcb(pid);
- if (dtcb == NULL)
- {
- /* The pid does not correspond to any known thread. The task
- * has probably already exited.
- */
- errcode = ESRCH;
- goto errout;
- }
- /* Only tasks and kernel threads can be deleted with this interface
- * (The semantics of the call should be sufficient to prohibit this).
- */
- DEBUGASSERT((dtcb->flags & TCB_FLAG_TTYPE_MASK) != TCB_FLAG_TTYPE_PTHREAD);
- /* Non-privileged tasks and pthreads may not delete privileged kernel
- * threads.
- *
- * REVISIT: We will need to look at this again in the future if/when
- * permissions are supported and a user task might also be priveleged.
- */
- if (((rtcb->flags & TCB_FLAG_TTYPE_MASK) != TCB_FLAG_TTYPE_KERNEL) &&
- ((dtcb->flags & TCB_FLAG_TTYPE_MASK) == TCB_FLAG_TTYPE_KERNEL))
- {
- errcode = EACCES;
- goto errout;
- }
- /* Check to see if this task has the non-cancelable bit set in its
- * flags. Suppress context changes for a bit so that the flags are stable.
- * (the flags should not change in interrupt handling).
- */
- sched_lock();
- if ((dtcb->flags & TCB_FLAG_NONCANCELABLE) != 0)
- {
- /* Then we cannot cancel the thread now. Here is how this is
- * supposed to work:
- *
- * "When cancelability is disabled, all cancels are held pending
- * in the target thread until the thread changes the cancelability.
- * When cancelability is deferred, all cancels are held pending in
- * the target thread until the thread changes the cancelability, calls
- * a function which is a cancellation point or calls pthread_testcancel(),
- * thus creating a cancellation point. When cancelability is asynchronous,
- * all cancels are acted upon immediately, interrupting the thread with its
- * processing."
- */
- dtcb->flags |= TCB_FLAG_CANCEL_PENDING;
- sched_unlock();
- return OK;
- }
- #ifdef CONFIG_CANCELLATION_POINTS
- /* Check if this task supports deferred cancellation */
- if ((dtcb->flags & TCB_FLAG_CANCEL_DEFERRED) != 0)
- {
- /* Then we cannot cancel the task asynchronously. Mark the cancellation
- * as pending.
- */
- dtcb->flags |= TCB_FLAG_CANCEL_PENDING;
- /* If the task is waiting at a cancellation point, then notify of the
- * cancellation thereby waking the task up with an ECANCELED error.
- */
- if (dtcb->cpcount > 0)
- {
- nxnotify_cancellation(dtcb);
- }
- sched_unlock();
- return OK;
- }
- #endif
- /* Check if the task to delete is the calling task */
- sched_unlock();
- if (pid == rtcb->pid)
- {
- /* If it is, then what we really wanted to do was exit. Note that we
- * don't bother to unlock the TCB since it will be going away.
- */
- exit(EXIT_SUCCESS);
- }
- /* Otherwise, perform the asynchronous cancellation, letting
- * nxtask_terminate() do all of the heavy lifting.
- */
- ret = nxtask_terminate(pid, false);
- if (ret < 0)
- {
- errcode = -ret;
- goto errout;
- }
- return OK;
- errout:
- set_errno(errcode);
- return ERROR;
- }
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