327 lines
9.1 KiB
C
327 lines
9.1 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 *chtcb;
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FAR struct tcb_s *otcb;
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FAR struct tcb_s *ptcb;
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pid_t opid;
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int ret = -ECHILD;
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/* Get the child tasks task group */
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chtcb = nxsched_get_tcb(chpid);
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if (chtcb)
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{
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chgrp = chtcb->group;
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DEBUGASSERT(chgrp);
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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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otcb = nxsched_get_tcb(opid);
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if (otcb)
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{
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ogrp = otcb->group;
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DEBUGASSERT(ogrp);
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/* If new parent task's PID (ppid) is zero, then new parent
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* is the grandparent will be the new parent, i.e.,
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* the parent of the current 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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ptcb = nxsched_get_tcb(ppid);
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if (ptcb)
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{
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ret = OK;
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pgrp = ptcb->group;
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}
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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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ptcb = nxsched_get_tcb(ppid);
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if (ptcb)
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{
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ret = OK;
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pgrp = chtcb->group;
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ppid = pgrp->tg_pid;
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}
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else
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{
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ret = -ESRCH;
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}
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}
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if (ret == OK)
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{
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/* Then reparent the child. Notice that we don't actually
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* change the parent of the task. Rather, we change the parent
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* task group for 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
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* status?
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*/
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if (!(atomic_read(&pgrp->tg_flags) & GROUP_FLAG_NOCLDWAIT))
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{
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/* No.. Add the child status entry to the new parent's
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* task group
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*/
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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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}
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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
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* group has suppressed child exit status.
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*/
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ret = ((atomic_read(&ogrp->tg_flags) &
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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(atomic_read(&ogrp->tg_nchildren) > 0);
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/* The original parent now has one few children */
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atomic_sub(&ogrp->tg_nchildren, 1);
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/* The new parent has one additional child */
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atomic_add(&pgrp->tg_nchildren, 1);
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#endif /* CONFIG_SCHED_CHILD_STATUS */
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nxsched_put_tcb(ptcb);
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}
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nxsched_put_tcb(otcb);
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}
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nxsched_put_tcb(chtcb);
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}
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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 = NULL;
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FAR struct tcb_s *chtcb = NULL;
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FAR struct tcb_s *otcb = NULL;
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pid_t opid;
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int ret = -ECHILD;
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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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/* 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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}
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else
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{
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/* If new parent task's PID (tg_ppid) is zero, then new parent
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* is the grandparent will be the new parent, i.e., the parent
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* of the current 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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}
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else
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{
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/* Then reparent the child. The task specified by ppid is
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* the new 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
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* exit status?
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* */
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if (!(atomic_read(&ptcb->group->tg_flags) &
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GROUP_FLAG_NOCLDWAIT))
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{
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/* No.. Add the child status entry to the new parent's
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* task group
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*/
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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
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* group has suppressed child exit status.
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*/
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ret = ((atomic_read(&otcb->group->tg_flags) &
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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(otcb->group != NULL &&
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atomic_read(&otcb->group->tg_nchildren) > 0);
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/* The original parent now has one few children */
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atomic_sub(&otcb->group->tg_nchildren, 1);
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/* The new parent has one additional child */
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atomic_add(&ptcb->group->tg_nchildren, 1);
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ret = OK;
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#endif /* CONFIG_SCHED_CHILD_STATUS */
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nxsched_put_tcb(ptcb);
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}
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nxsched_put_tcb(otcb);
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}
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nxsched_put_tcb(chtcb);
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}
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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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