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/****************************************************************************
* sched/task_exit.c
*
* Copyright (C) 2008-2009, 2012-2013 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 <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_exit
*
* Description:
* This is a part of the logic used to implement _exit(). The full
* implementation of _exit() is architecture-dependent. The _exit()
* function also implements the bottom half of exit() and pthread_exit().
*
* This function causes the currently running task (i.e., the task at the
* head of the ready-to-run list) to cease to exist. This function should
* never be called from normal user code, but only from the architecture-
* specific implementation of exit.
*
* Threads/tasks could also be terminated via pthread_cancel, task_delete(),
* and task_restart(). In the last two cases, the task will be terminated
* as though exit() were called.
*
* Inputs:
* None
*
* Return Value:
* OK on success; or ERROR on failure
*
* Assumeptions:
* Interrupts are disabled.
*
****************************************************************************/
int task_exit(void)
{
FAR struct tcb_s *dtcb = (FAR struct tcb_s*)g_readytorun.head;
FAR struct tcb_s *rtcb;
/* Remove the TCB of the current task from the ready-to-run list. A context
* switch will definitely be necessary -- that must be done by the
* architecture-specific logic.
*
* sched_removereadytorun will mark the task at the head of the ready-to-run
* with state == TSTATE_TASK_RUNNING
*/
(void)sched_removereadytorun(dtcb);
rtcb = (FAR struct tcb_s*)g_readytorun.head;
/* We are now in a bad state -- the head of the ready to run task list
* does not correspond to the thread that is running. Disabling pre-
* emption on this TCB and marking the new ready-to-run task as not
* running (see, for example, get_errno_ptr()).
*
* We disable pre-emption here by directly incrementing the lockcount
* (vs. calling sched_lock()).
*/
rtcb->lockcount++;
rtcb->task_state = TSTATE_TASK_READYTORUN;
/* Move the TCB to the specified blocked task list and delete it. Calling
* task_terminate with non-blocking true will suppress atexit() and on-exit()
* calls and will cause buffered I/O to fail to be flushed. The former
* is required _exit() behavior; the latter is optional _exit() behavior.
*/
sched_addblocked(dtcb, TSTATE_TASK_INACTIVE);
task_terminate(dtcb->pid, true);
rtcb->task_state = TSTATE_TASK_RUNNING;
/* If there are any pending tasks, then add them to the ready-to-run
* task list now
*/
if (g_pendingtasks.head)
{
(void)sched_mergepending();
}
/* We can't use sched_unlock() to decrement the lock count because the
* sched_mergepending() call above might have changed the task at the
* head of the ready-to-run list. Furthermore, we should not need to
* perform the unlock action anyway because we know that the pending
* task list is empty. So all we really need to do is to decrement
* the lockcount on rctb.
*/
rtcb->lockcount--;
return OK;
}
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