forked from Archive/PX4-Autopilot
321 lines
8.2 KiB
C
321 lines
8.2 KiB
C
/*****************************************************************************
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* sched/task_reparent.c
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*
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* Copyright (C) 2013 Gregory Nutt. All rights reserved.
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* Author: Gregory Nutt <gnutt@nuttx.org>
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* distribution.
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* 3. Neither the name NuttX nor the names of its contributors may be
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* used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
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* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
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* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
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* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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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 <errno.h>
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#include "os_internal.h"
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#include "group_internal.h"
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#ifdef CONFIG_SCHED_HAVE_PARENT
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/*****************************************************************************
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* Private Functions
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*****************************************************************************/
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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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* 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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* Return 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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_TCB *tcb;
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gid_t ogid;
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gid_t pgid;
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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 relatinoship of
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* the three task: Child, current parent, and new parent.
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*/
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flags = irqsave();
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/* Get the child tasks task group */
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tcb = sched_gettcb(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 GID of the old parent task's task group (ogid) */
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ogid = chgrp->tg_pgid;
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/* Get the old parent task's task group (ogrp) */
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ogrp = group_find(ogid);
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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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pgid = ogrp->tg_pgid;
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pgrp = group_find(pgid);
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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 = sched_gettcb(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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pgid = pgrp->tg_gid;
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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_pgid = pgid;
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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_removechild(ogrp, chpid);
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if (child)
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{
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/* Has the new parent's task group supressed 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_addchild(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_freechild(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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DEBUGASSERT(otcb->nchildren > 0);
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otcb->nchildren--; /* The orignal parent now has one few children */
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ptcb->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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irqrestore(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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_TCB *ptcb;
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_TCB *chtcb;
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_TCB *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 relatinoship of
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* the three task: Child, current parent, and new parent.
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*/
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flags = irqsave();
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/* Get the child tasks TCB (chtcb) */
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chtcb = sched_gettcb(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->ppid;
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/* Get the TCB of the child task's parent (otcb) */
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otcb = sched_gettcb(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 (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->ppid;
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}
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/* Get the new parent task's TCB (ptcb) */
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ptcb = sched_gettcb(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 */
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chtcb->ppid = ppid; /* The task specified by ppid is the new parent */
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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_removechild(otcb->group, chpid);
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if (child)
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{
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/* Has the new parent's task group supressed 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_addchild(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_freechild(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) ? -ENOENT : OK;
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}
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#else /* CONFIG_SCHED_CHILD_STATUS */
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DEBUGASSERT(otcb->nchildren > 0);
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otcb->nchildren--; /* The orignal parent now has one few children */
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ptcb->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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irqrestore(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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