forked from Archive/PX4-Autopilot
228 lines
7.4 KiB
C
228 lines
7.4 KiB
C
/*****************************************************************************
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* sched/group_join.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 <sched.h>
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#include <assert.h>
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#include <errno.h>
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#include <debug.h>
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#include <nuttx/kmalloc.h>
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#include "group_internal.h"
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#include "env_internal.h"
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#ifdef HAVE_TASK_GROUP
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/*****************************************************************************
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* Pre-processor Definitions
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*****************************************************************************/
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/* Is this worth making a configuration option? */
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#define GROUP_REALLOC_MEMBERS 4
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/*****************************************************************************
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* Private Types
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*****************************************************************************/
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/*****************************************************************************
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* Private Data
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*****************************************************************************/
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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: group_bind
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*
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* Description:
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* A thread joins the group when it is created. This is a two step process,
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* first, the group must bound to the new threads TCB. group_bind() does
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* this (at the return from group_join, things are a little unstable: The
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* group has been bound, but tg_nmembers hs not yet been incremented).
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* Then, after the new thread is initialized and has a PID assigned to it,
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* group_join() is called, incrementing the tg_nmembers count on the group.
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*
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* Parameters:
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* tcb - The TCB of the new "child" task that need to join the group.
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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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* Assumptions:
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* - The parent task from which the group will be inherited is the task at
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* the thead of the ready to run list.
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* - Called during thread creation in a safe context. No special precautions
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* are required here.
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*
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*****************************************************************************/
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int group_bind(FAR _TCB *tcb)
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{
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FAR _TCB *ptcb = (FAR _TCB *)g_readytorun.head;
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DEBUGASSERT(ptcb && tcb && ptcb->group && !tcb->group);
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/* Copy the group reference from the parent to the child */
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tcb->group = ptcb->group;
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return OK;
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}
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/*****************************************************************************
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* Name: group_join
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*
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* Description:
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* A thread joins the group when it is created. This is a two step process,
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* first, the group must bound to the new threads TCB. group_bind() does
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* this (at the return from group_join, things are a little unstable: The
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* group has been bound, but tg_nmembers hs not yet been incremented).
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* Then, after the new thread is initialized and has a PID assigned to it,
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* group_join() is called, incrementing the tg_nmembers count on the group.
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*
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* Parameters:
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* tcb - The TCB of the new "child" task that need to join the group.
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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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* Assumptions:
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* - The parent task from which the group will be inherited is the task at
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* the thead of the ready to run list.
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* - Called during thread creation in a safe context. No special precautions
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* are required here.
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*
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*****************************************************************************/
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int group_join(FAR _TCB *tcb)
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{
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FAR struct task_group_s *group;
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#ifdef HAVE_GROUP_MEMBERS
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int ret;
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#endif
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DEBUGASSERT(tcb && tcb->group &&
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tcb->group->tg_nmembers < UINT8_MAX);
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/* Get the group from the TCB */
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group = tcb->group;
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#ifdef HAVE_GROUP_MEMBERS
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/* Add the member to the group */
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ret = group_addmember(group, tcb->pid);
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if (ret < 0)
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{
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return ret;
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}
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#endif
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group->tg_nmembers++;
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return OK;
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}
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/*****************************************************************************
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* Name: group_addmember
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*
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* Description:
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* Add a new member to a group.
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*
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* Parameters:
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* group - The task group to add the new member
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* pid - The new member
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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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* Assumptions:
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* Called during thread creation and during reparenting in a safe context.
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* No special precautions are required here.
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*
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*****************************************************************************/
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#ifdef HAVE_GROUP_MEMBERS
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int group_addmember(FAR struct task_group_s *group, pid_t pid)
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{
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DEBUGASSERT(group && group->tg_nmembers < UINT8_MAX);
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/* Will we need to extend the size of the array of groups? */
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if (group->tg_nmembers >= group->tg_mxmembers)
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{
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FAR pid_t *newmembers;
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unsigned int newmax;
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/* Yes... reallocate the array of members */
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newmax = group->tg_mxmembers + GROUP_REALLOC_MEMBERS;
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if (newmax > UINT8_MAX)
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{
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newmax = UINT8_MAX;
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}
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newmembers = (FAR pid_t *)
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krealloc(group->tg_members, sizeof(pid_t) * newmax);
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if (!newmembers)
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{
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return -ENOMEM;
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}
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/* Save the new number of members in the reallocated members array */
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group->tg_members = newmembers;
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group->tg_mxmembers = newmax;
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}
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/* Assign this new pid to the group. */
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group->tg_members[group->tg_nmembers] = pid;
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return OK;
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}
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#endif /* HAVE_GROUP_MEMBERS */
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#endif /* HAVE_TASK_GROUP */
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