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/****************************************************************************
* sched/task_delete.c
*
* Copyright (C) 2007-2009, 2011-2012 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 <sys/types.h>
#include <stdlib.h>
#include <sched.h>
#include "os_internal.h"
#ifndef CONFIG_DISABLE_SIGNALS
# include "sig_internal.h"
#endif
/****************************************************************************
* Definitions
****************************************************************************/
/****************************************************************************
* Private Type Declarations
****************************************************************************/
/****************************************************************************
* Global Variables
****************************************************************************/
/****************************************************************************
* Private Variables
****************************************************************************/
/****************************************************************************
* Private Function Prototypes
****************************************************************************/
/****************************************************************************
* Private Functions
****************************************************************************/
/****************************************************************************
* 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().
*
* 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().
*
* Control will still be returned to task_delete() after the exit() logic
* finishes. In fact, this function is the final function called all task
* termination sequences. Here are all possible exit scenarios:
*
* - pthread_exit(). Calls exit()
* - exit(). Calls _exit()
* - _exit(). Calls task_deletecurrent() making the currently running task
* non-running then calls task_delete() to terminate the non-running
* task.
* - task_delete()
*
* Inputs:
* pid - The task ID of the task to delete. A pid of zero
* signifies the calling task.
*
* Return Value:
* OK on success; or ERROR on failure
*
* This function can fail if the provided pid does not correspond to a
* task (errno is not set)
*
****************************************************************************/
int task_delete(pid_t pid)
{
FAR _TCB *rtcb;
FAR _TCB *dtcb;
irqstate_t saved_state;
int ret = ERROR;
/* Check if the task to delete is the calling task */
rtcb = (FAR _TCB*)g_readytorun.head;
if (pid == 0 || 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);
}
/* Make sure the task does not become ready-to-run while we are futzing with
* its TCB by locking ourselves as the executing task.
*/
sched_lock();
/* Find for the TCB associated with matching pid */
dtcb = sched_gettcb(pid);
if (!dtcb)
{
/* This pid does not correspond to any known task */
sched_unlock();
return ERROR;
}
/* Verify our internal sanity */
if (dtcb->task_state == TSTATE_TASK_RUNNING ||
dtcb->task_state >= NUM_TASK_STATES)
{
sched_unlock();
PANIC(OSERR_BADDELETESTATE);
}
/* Perform common task termination logic (flushing streams, calling
* functions registered by at_exit/on_exit, etc.). We need to do
* this as early as possible so that higher level clean-up logic
* can run in a healthy tasking environment.
*
* In the case where the task exits via exit(), task_exithook()
* may be called twice.
*
* I suppose EXIT_SUCCESS is an appropriate return value???
*/
task_exithook(dtcb, EXIT_SUCCESS);
/* Remove the task from the OS's tasks lists. */
saved_state = irqsave();
dq_rem((FAR dq_entry_t*)dtcb, (dq_queue_t*)g_tasklisttable[dtcb->task_state].list);
dtcb->task_state = TSTATE_TASK_INVALID;
irqrestore(saved_state);
/* At this point, the TCB should no longer be accessible to the system */
sched_unlock();
/* Since all tasks pass through this function as the final step in their
* exit sequence, this is an appropriate place to inform any instrumentation
* layer that the task no longer exists.
*/
sched_note_stop(dtcb);
/* Deallocate its TCB */
sched_releasetcb(dtcb);
return ret;
}
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