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/*****************************************************************************
* sched/group_join.c
*
* Copyright (C) 2013 Gregory Nutt. All rights reserved.
* Author: Gregory Nutt <gnutt@nuttx.org>
*
* 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 <nuttx/config.h>
#include <sched.h>
#include <assert.h>
#include <errno.h>
#include <debug.h>
#include <nuttx/kmalloc.h>
#include "os_internal.h"
#ifdef HAVE_TASK_GROUP
/*****************************************************************************
* Pre-processor Definitions
*****************************************************************************/
/* Is this worth making a configuration option? */
#define GROUP_REALLOC_MEMBERS 4
/*****************************************************************************
* Private Types
*****************************************************************************/
/*****************************************************************************
* Private Data
*****************************************************************************/
/*****************************************************************************
* Private Functions
*****************************************************************************/
/*****************************************************************************
* Public Functions
*****************************************************************************/
/*****************************************************************************
* Name: group_bind
*
* Description:
* A thread joins the group when it is created. This is a two step process,
* first, the group must bound to the new threads TCB. group_bind() does
* this (at the return from group_join, things are a little unstable: The
* group has been bound, but tg_nmembers hs not yet been incremented).
* Then, after the new thread is initialized and has a PID assigned to it,
* group_join() is called, incrementing the tg_nmembers count on the group.
*
* Parameters:
* tcb - The TCB of the new "child" task that need to join the group.
*
* Return Value:
* 0 (OK) on success; a negated errno value on failure.
*
* Assumptions:
* - The parent task from which the group will be inherited is the task at
* the thead of the ready to run list.
* - Called during thread creation in a safe context. No special precautions
* are required here.
*
*****************************************************************************/
int group_bind(FAR _TCB *tcb)
{
FAR _TCB *ptcb = (FAR _TCB *)g_readytorun.head;
DEBUGASSERT(ptcb && tcb && ptcb->group && !tcb->group);
/* Copy the group reference from the parent to the child */
tcb->group = ptcb->group;
return OK;
}
/*****************************************************************************
* Name: group_join
*
* Description:
* A thread joins the group when it is created. This is a two step process,
* first, the group must bound to the new threads TCB. group_bind() does
* this (at the return from group_join, things are a little unstable: The
* group has been bound, but tg_nmembers hs not yet been incremented).
* Then, after the new thread is initialized and has a PID assigned to it,
* group_join() is called, incrementing the tg_nmembers count on the group.
*
* Parameters:
* tcb - The TCB of the new "child" task that need to join the group.
*
* Return Value:
* 0 (OK) on success; a negated errno value on failure.
*
* Assumptions:
* - The parent task from which the group will be inherited is the task at
* the thead of the ready to run list.
* - Called during thread creation in a safe context. No special precautions
* are required here.
*
*****************************************************************************/
int group_join(FAR _TCB *tcb)
{
#ifdef HAVE_GROUP_MEMBERS
FAR struct task_group_s *group;
DEBUGASSERT(tcb && tcb->group &&
tcb->group->tg_nmembers < UINT8_MAX);
/* Get the group from the TCB */
group = tcb->group;
/* Will we need to extend the size of the array of groups? */
if (group->tg_nmembers >= group->tg_mxmembers)
{
FAR pid_t *newmembers;
unsigned int newmax;
/* Yes... reallocate the array of members */
newmax = group->tg_mxmembers + GROUP_REALLOC_MEMBERS;
if (newmax > UINT8_MAX)
{
newmax = UINT8_MAX;
}
newmembers = (FAR pid_t *)
krealloc(group->tg_members, sizeof(pid_t) * newmax);
if (!newmembers)
{
return -ENOMEM;
}
/* Save the new number of members in the reallocated members array */
group->tg_members = newmembers;
group->tg_mxmembers = newmax;
}
/* Assign this new pid to the group. */
group->tg_members[group->tg_nmembers] = tcb->pid;
#endif
group->tg_nmembers++;
return OK;
}
#endif /* HAVE_TASK_GROUP */
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