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/*****************************************************************************
* sched/task_reparent.c
*
* Copyright (C) 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 <errno.h>
#include "os_internal.h"
#ifdef CONFIG_SCHED_HAVE_PARENT
/*****************************************************************************
* Private Functions
*****************************************************************************/
/*****************************************************************************
* Public Functions
*****************************************************************************/
/*****************************************************************************
* Name: task_reparent
*
* Description:
* Change the parent of a task.
*
* Parameters:
* oldpid - PID of the old parent task (0 if this task)
* newpid - PID ot the new parent task (0 for the parent of this task)
* chpid - PID of the child to be reparented.
*
* Return Value:
* 0 (OK) on success; A negated errno value on failure.
*
*****************************************************************************/
int task_reparent(pid_t oldpid, pid_t newpid, pid_t chpid)
{
_TCB *oldtcb;
_TCB *newtcb;
_TCB *chtcb;
irqstate_t flags;
int ret;
/* If oldpid is zero, then we are parent task. */
if (oldpid == 0)
{
oldpid = getpid();
}
/* Get the current parent task's TCB */
oldtcb = sched_gettcb(oldpid);
if (!oldtcb)
{
return -ESRCH;
}
/* Disable interrupts so that nothing can change from this point */
flags = irqsave();
/* If newpid is zero, then new is the parent of oldpid. */
if (newpid == 0)
{
newpid = oldtcb->parent;
}
/* Get the new parent task's TCB */
newtcb = sched_gettcb(newpid);
if (!newtcb)
{
ret = -ESRCH;
goto errout_with_ints;
}
/* Get the child tasks TCB */
chtcb = sched_gettcb(chpid);
if (!chtcb)
{
ret = -ECHILD;
goto errout_with_ints;
}
/* Verify that oldpid is the parent of chpid */
if (chtcb->parent != oldpid)
{
ret = -ECHILD;
goto errout_with_ints;
}
/* Okay, reparent the child */
DEBUGASSERT(oldtcb->nchildren > 0);
chtcb->parent = newpid;
oldtcb->nchildren--;
newtcb->nchildren++;
ret = OK;
errout_with_ints:
irqrestore(flags);
return ret;
}
#endif /* CONFIG_SCHED_HAVE_PARENT */
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