313 lines
7.7 KiB
C
313 lines
7.7 KiB
C
/****************************************************************************
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* sched/task/task_reparent.c
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*
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* SPDX-License-Identifier: Apache-2.0
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*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership. The
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* ASF licenses this file to you under the Apache License, Version 2.0 (the
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* "License"); you may not use this file except in compliance with the
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* License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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* License for the specific language governing permissions and limitations
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* under the License.
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*
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****************************************************************************/
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/****************************************************************************
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* Included Files
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****************************************************************************/
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#include <nuttx/config.h>
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#include <assert.h>
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#include <errno.h>
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#include <nuttx/irq.h>
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#include <nuttx/sched.h>
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#include "sched/sched.h"
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#include "group/group.h"
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#include "task/task.h"
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#ifdef CONFIG_SCHED_HAVE_PARENT
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: task_reparent
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*
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* Description:
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* Change the parent of a task.
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*
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* Input Parameters:
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* ppid - PID of the new parent task (0 for grandparent, i.e. the parent
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* of the current parent task)
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* chpid - PID of the child to be reparented.
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*
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* Returned Value:
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* 0 (OK) on success; A negated errno value on failure.
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*
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****************************************************************************/
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#ifdef HAVE_GROUP_MEMBERS
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int task_reparent(pid_t ppid, pid_t chpid)
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{
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#ifdef CONFIG_SCHED_CHILD_STATUS
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FAR struct child_status_s *child;
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#endif
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FAR struct task_group_s *chgrp;
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FAR struct task_group_s *ogrp;
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FAR struct task_group_s *pgrp;
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FAR struct tcb_s *tcb;
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irqstate_t flags;
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pid_t opid;
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int ret;
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/* Disable interrupts so that nothing can change in the relationship of
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* the three task: Child, current parent, and new parent.
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*/
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flags = enter_critical_section();
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/* Get the child tasks task group */
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tcb = nxsched_get_tcb(chpid);
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if (!tcb)
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{
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ret = -ECHILD;
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goto errout_with_ints;
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}
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DEBUGASSERT(tcb->group);
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chgrp = tcb->group;
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/* Get the PID of the old parent task's task group (opid) */
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opid = chgrp->tg_ppid;
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/* Get the old parent task's task group (ogrp) */
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ogrp = task_getgroup(opid);
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if (!ogrp)
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{
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ret = -ESRCH;
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goto errout_with_ints;
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}
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/* If new parent task's PID (ppid) is zero, then new parent is the
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* grandparent will be the new parent, i.e., the parent of the current
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* parent task.
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*/
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if (ppid == 0)
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{
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/* Get the grandparent task's task group (pgrp) */
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ppid = ogrp->tg_ppid;
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pgrp = task_getgroup(ppid);
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}
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else
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{
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/* Get the new parent task's task group (pgrp) */
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tcb = nxsched_get_tcb(ppid);
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if (!tcb)
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{
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ret = -ESRCH;
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goto errout_with_ints;
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}
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pgrp = tcb->group;
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ppid = pgrp->tg_pid;
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}
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if (!pgrp)
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{
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ret = -ESRCH;
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goto errout_with_ints;
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}
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/* Then reparent the child. Notice that we don't actually change the
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* parent of the task. Rather, we change the parent task group for
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* all members of the child's task group.
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*/
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chgrp->tg_ppid = ppid;
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#ifdef CONFIG_SCHED_CHILD_STATUS
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/* Remove the child status entry from old parent task group */
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child = group_remove_child(ogrp, chpid);
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if (child)
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{
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/* Has the new parent's task group suppressed child exit status? */
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if ((pgrp->tg_flags & GROUP_FLAG_NOCLDWAIT) == 0)
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{
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/* No.. Add the child status entry to the new parent's task group */
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group_add_child(pgrp, child);
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}
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else
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{
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/* Yes.. Discard the child status entry */
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group_free_child(child);
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}
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/* Either case is a success */
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ret = OK;
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}
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else
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{
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/* This would not be an error if the original parent's task group has
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* suppressed child exit status.
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*/
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ret = ((ogrp->tg_flags & GROUP_FLAG_NOCLDWAIT) == 0) ? -ENOENT : OK;
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}
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#else /* CONFIG_SCHED_CHILD_STATUS */
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/* Child task exit status is not retained */
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DEBUGASSERT(ogrp->tg_nchildren > 0);
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ogrp->tg_nchildren--; /* The original parent now has one few children */
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pgrp->tg_nchildren++; /* The new parent has one additional child */
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ret = OK;
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#endif /* CONFIG_SCHED_CHILD_STATUS */
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errout_with_ints:
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leave_critical_section(flags);
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return ret;
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}
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#else
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int task_reparent(pid_t ppid, pid_t chpid)
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{
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#ifdef CONFIG_SCHED_CHILD_STATUS
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FAR struct child_status_s *child;
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#endif
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FAR struct tcb_s *ptcb;
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FAR struct tcb_s *chtcb;
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FAR struct tcb_s *otcb;
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pid_t opid;
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irqstate_t flags;
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int ret;
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/* Disable interrupts so that nothing can change in the relationship of
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* the three task: Child, current parent, and new parent.
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*/
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flags = enter_critical_section();
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/* Get the child tasks TCB (chtcb) */
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chtcb = nxsched_get_tcb(chpid);
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if (!chtcb)
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{
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ret = -ECHILD;
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goto errout_with_ints;
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}
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/* Get the PID of the child task's parent (opid) */
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opid = chtcb->group->tg_ppid;
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/* Get the TCB of the child task's parent (otcb) */
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otcb = nxsched_get_tcb(opid);
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if (!otcb)
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{
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ret = -ESRCH;
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goto errout_with_ints;
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}
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/* If new parent task's PID (tg_ppid) is zero, then new parent is the
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* grandparent will be the new parent, i.e., the parent of the current
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* parent task.
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*/
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if (ppid == 0)
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{
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ppid = otcb->group->tg_ppid;
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}
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/* Get the new parent task's TCB (ptcb) */
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ptcb = nxsched_get_tcb(ppid);
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if (!ptcb)
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{
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ret = -ESRCH;
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goto errout_with_ints;
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}
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/* Then reparent the child. The task specified by ppid is the new
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* parent.
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*/
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chtcb->group->tg_ppid = ppid;
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#ifdef CONFIG_SCHED_CHILD_STATUS
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/* Remove the child status entry from old parent TCB */
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child = group_remove_child(otcb->group, chpid);
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if (child)
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{
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/* Has the new parent's task group suppressed child exit status? */
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if ((ptcb->group->tg_flags & GROUP_FLAG_NOCLDWAIT) == 0)
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{
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/* No.. Add the child status entry to the new parent's task group */
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group_add_child(ptcb->group, child);
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}
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else
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{
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/* Yes.. Discard the child status entry */
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group_free_child(child);
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}
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/* Either case is a success */
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ret = OK;
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}
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else
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{
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/* This would not be an error if the original parent's task group has
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* suppressed child exit status.
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*/
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ret = ((otcb->group->tg_flags & GROUP_FLAG_NOCLDWAIT) == 0) ?
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-ENOENT : OK;
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}
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#else /* CONFIG_SCHED_CHILD_STATUS */
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/* Child task exit status is not retained */
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DEBUGASSERT(otcb->group != NULL && otcb->group->tg_nchildren > 0);
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otcb->group->tg_nchildren--; /* The original parent now has one few children */
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ptcb->group->tg_nchildren++; /* The new parent has one additional child */
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ret = OK;
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#endif /* CONFIG_SCHED_CHILD_STATUS */
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errout_with_ints:
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leave_critical_section(flags);
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return ret;
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}
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#endif
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#endif /* CONFIG_SCHED_HAVE_PARENT */
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