nuttx/sched/task_restart.c

/****************************************************************************
 * sched/task_restart.c
 *
 *   Copyright (C) 2007, 2009, 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 <sched.h>
#include <nuttx/arch.h>
#include "os_internal.h"
#include "sig_internal.h"

/****************************************************************************
 * Definitions
 ****************************************************************************/

/****************************************************************************
 * Private Type Declarations
 ****************************************************************************/

/****************************************************************************
 * Global Variables
 ****************************************************************************/

/****************************************************************************
 * Private Variables
 ****************************************************************************/

/****************************************************************************
 * Private Function Prototypes
 ****************************************************************************/

/****************************************************************************
 * Private Functions
 ****************************************************************************/

/****************************************************************************
 * Public Functions
 ****************************************************************************/

/****************************************************************************
 * Name: task_restart
 *
 * Description:
 *   This function "restarts" a task.  The task is first
 *   terminated and then reinitialized with same ID, priority,
 *   original entry point, stack size, and parameters it had
 *   when it was first started.
 *
 * Inputs:
 *   pid - The task ID of the task to delete.  An ID of zero
 *         signifies the calling task.
 *
 * Return Value:
 *   OK on sucess; ERROR on failure.
 *
 *   This function can fail if:
 *   (1) A pid of zero or the pid of the calling task is
 *       provided (functionality not implemented)
 *   (2) The pid is not associated with any task known to
 *       the system.
 *
 ****************************************************************************/

int task_restart(pid_t pid)
{
  FAR _TCB  *rtcb;
  FAR _TCB  *tcb;
  int        status;
  irqstate_t state;

  /* Make sure this task does not become ready-to-run while
   * we are futzing with its TCB
   */

   sched_lock();

   /* Check if the task to restart is the calling task */

   rtcb = (FAR _TCB*)g_readytorun.head;
   if ((pid == 0) || (pid == rtcb->pid))
     {
       /* Not implemented */

       return ERROR;
     }

   /* We are restarting some other task than ourselves */

   else
     {
       /* Find for the TCB associated with matching pid  */

       tcb = sched_gettcb(pid);
       if (!tcb)
         {
           /* There is no TCB with this pid */

           return ERROR;
         }

       /* Remove the TCB from whatever list it is in.  At this point, the
        * TCB should no longer be accessible to the system 
        */

       state = irqsave();
       dq_rem((FAR dq_entry_t*)tcb, (dq_queue_t*)g_tasklisttable[tcb->task_state].list);
       tcb->task_state = TSTATE_TASK_INVALID;
       irqrestore(state);

       /* Deallocate anything left in the TCB's queues */

       sig_cleanup(tcb); /* Deallocate Signal lists */

       /* Reset the current task priority  */

       tcb->sched_priority = tcb->init_priority;

       /* Reset the base task priority and the number of pending reprioritizations */

#ifdef CONFIG_PRIORITY_INHERITANCE
       tcb->base_priority  = tcb->init_priority;
#  if CONFIG_SEM_NNESTPRIO > 0
       tcb->npend_reprio   = 0;
#  endif
#endif

       /* Re-initialize the processor-specific portion of the TCB
        * This will reset the entry point and the start-up parameters
        */

       up_initial_state(tcb);

       /* Add the task to the inactive task list */

       dq_addfirst((FAR dq_entry_t*)tcb, (dq_queue_t*)&g_inactivetasks);
       tcb->task_state = TSTATE_TASK_INACTIVE;

       /* Activate the task */

       status = task_activate(tcb);
       if (status != OK)
         {
           dq_rem((FAR dq_entry_t*)tcb, (dq_queue_t*)&g_inactivetasks);
           sched_releasetcb(tcb);
           return ERROR;
         }
     }

  sched_unlock();
  return OK;
}