/**************************************************************************** * sched/task/task_reparent.c * * Copyright (C) 2013, 2016 Gregory Nutt. All rights reserved. * Author: Gregory Nutt * * 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 #include #include #include "sched/sched.h" #include "group/group.h" #include "task/task.h" #ifdef CONFIG_SCHED_HAVE_PARENT /**************************************************************************** * Public Functions ****************************************************************************/ /**************************************************************************** * Name: task_reparent * * Description: * Change the parent of a task. * * Input Parameters: * ppid - PID of the new parent task (0 for grandparent, i.e. the parent * of the current parent task) * chpid - PID of the child to be reparented. * * Returned Value: * 0 (OK) on success; A negated errno value on failure. * ****************************************************************************/ #ifdef HAVE_GROUP_MEMBERS int task_reparent(pid_t ppid, pid_t chpid) { #ifdef CONFIG_SCHED_CHILD_STATUS FAR struct child_status_s *child; #endif FAR struct task_group_s *chgrp; FAR struct task_group_s *ogrp; FAR struct task_group_s *pgrp; struct tcb_s *tcb; gid_t ogid; gid_t pgid; irqstate_t flags; int ret; /* Disable interrupts so that nothing can change in the relationship of * the three task: Child, current parent, and new parent. */ flags = enter_critical_section(); /* Get the child tasks task group */ tcb = sched_gettcb(chpid); if (!tcb) { ret = -ECHILD; goto errout_with_ints; } DEBUGASSERT(tcb->group); chgrp = tcb->group; /* Get the GID of the old parent task's task group (ogid) */ ogid = chgrp->tg_pgid; /* Get the old parent task's task group (ogrp) */ ogrp = group_findbygid(ogid); if (!ogrp) { ret = -ESRCH; goto errout_with_ints; } /* If new parent task's PID (ppid) is zero, then new parent is the * grandparent will be the new parent, i.e., the parent of the current * parent task. */ if (ppid == 0) { /* Get the grandparent task's task group (pgrp) */ pgid = ogrp->tg_pgid; pgrp = group_findbygid(pgid); } else { /* Get the new parent task's task group (pgrp) */ tcb = sched_gettcb(ppid); if (!tcb) { ret = -ESRCH; goto errout_with_ints; } pgrp = tcb->group; pgid = pgrp->tg_gid; } if (!pgrp) { ret = -ESRCH; goto errout_with_ints; } /* Then reparent the child. Notice that we don't actually change the * parent of the task. Rather, we change the parent task group for * all members of the child's task group. */ chgrp->tg_pgid = pgid; #ifdef CONFIG_SCHED_CHILD_STATUS /* Remove the child status entry from old parent task group */ child = group_removechild(ogrp, chpid); if (child) { /* Has the new parent's task group supressed child exit status? */ if ((pgrp->tg_flags & GROUP_FLAG_NOCLDWAIT) == 0) { /* No.. Add the child status entry to the new parent's task group */ group_addchild(pgrp, child); } else { /* Yes.. Discard the child status entry */ group_freechild(child); } /* Either case is a success */ ret = OK; } else { /* This would not be an error if the original parent's task group has * suppressed child exit status. */ ret = ((ogrp->tg_flags & GROUP_FLAG_NOCLDWAIT) == 0) ? -ENOENT : OK; } #else /* CONFIG_SCHED_CHILD_STATUS */ /* Child task exit status is not retained */ DEBUGASSERT(ogrp->tg_nchildren > 0); ogrp->tg_nchildren--; /* The orignal parent now has one few children */ pgrp->tg_nchildren++; /* The new parent has one additional child */ ret = OK; #endif /* CONFIG_SCHED_CHILD_STATUS */ errout_with_ints: leave_critical_section(flags); return ret; } #else int task_reparent(pid_t ppid, pid_t chpid) { #ifdef CONFIG_SCHED_CHILD_STATUS FAR struct child_status_s *child; #endif struct tcb_s *ptcb; struct tcb_s *chtcb; struct tcb_s *otcb; pid_t opid; irqstate_t flags; int ret; /* Disable interrupts so that nothing can change in the relationship of * the three task: Child, current parent, and new parent. */ flags = enter_critical_section(); /* Get the child tasks TCB (chtcb) */ chtcb = sched_gettcb(chpid); if (!chtcb) { ret = -ECHILD; goto errout_with_ints; } /* Get the PID of the child task's parent (opid) */ opid = chtcb->group->tg_ppid; /* Get the TCB of the child task's parent (otcb) */ otcb = sched_gettcb(opid); if (!otcb) { ret = -ESRCH; goto errout_with_ints; } /* If new parent task's PID (tg_ppid) is zero, then new parent is the * grandparent will be the new parent, i.e., the parent of the current * parent task. */ if (ppid == 0) { ppid = otcb->group->tg_ppid; } /* Get the new parent task's TCB (ptcb) */ ptcb = sched_gettcb(ppid); if (!ptcb) { ret = -ESRCH; goto errout_with_ints; } /* Then reparent the child. The task specified by ppid is the new parent. */ chtcb->group->tg_ppid = ppid; #ifdef CONFIG_SCHED_CHILD_STATUS /* Remove the child status entry from old parent TCB */ child = group_removechild(otcb->group, chpid); if (child) { /* Has the new parent's task group supressed child exit status? */ if ((ptcb->group->tg_flags & GROUP_FLAG_NOCLDWAIT) == 0) { /* No.. Add the child status entry to the new parent's task group */ group_addchild(ptcb->group, child); } else { /* Yes.. Discard the child status entry */ group_freechild(child); } /* Either case is a success */ ret = OK; } else { /* This would not be an error if the original parent's task group has * suppressed child exit status. */ ret = ((otcb->group->tg_flags & GROUP_FLAG_NOCLDWAIT) == 0) ? -ENOENT : OK; } #else /* CONFIG_SCHED_CHILD_STATUS */ /* Child task exit status is not retained */ DEBUGASSERT(otcb->group != NULL && otcb->group->tg_nchildren > 0); otcb->group->tg_nchildren--; /* The orignal parent now has one few children */ ptcb->group->tg_nchildren++; /* The new parent has one additional child */ ret = OK; #endif /* CONFIG_SCHED_CHILD_STATUS */ errout_with_ints: leave_critical_section(flags); return ret; } #endif #endif /* CONFIG_SCHED_HAVE_PARENT */