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320 lines
8.2 KiB
320 lines
8.2 KiB
/***************************************************************************** |
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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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