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px4-firmware/nuttx/sched/group_leave.c

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/*****************************************************************************
* sched/group_leave.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 "group_internal.h"
#include "env_internal.h"
#ifdef HAVE_TASK_GROUP
/*****************************************************************************
* Pre-processor Definitions
*****************************************************************************/
/*****************************************************************************
* Private Types
*****************************************************************************/
/*****************************************************************************
* Private Data
*****************************************************************************/
/*****************************************************************************
* Private Functions
*****************************************************************************/
/*****************************************************************************
* Name: group_remove
*
* Description:
* Remove a group from the list of groups.
*
* Parameters:
* group - The group to be removed.
*
* Return Value:
* None.
*
* Assumptions:
* Called during task deletion in a safe context. No special precautions
* are required here.
*
*****************************************************************************/
#ifdef HAVE_GROUP_MEMBERS
void group_remove(FAR struct task_group_s *group)
{
FAR struct task_group_s *curr;
FAR struct task_group_s *prev;
irqstate_t flags;
/* Let's be especially careful while access the global task group list.
* This is probably un-necessary.
*/
flags = irqsave();
/* Find the task group structure */
for (prev = NULL, curr = g_grouphead;
curr && curr != group;
prev = curr, curr = curr->flink);
/* Did we find it? If so, remove it from the list. */
if (curr)
{
/* Do we remove it from mid-list? Or from the head of the list? */
if (prev)
{
prev->flink = curr->flink;
}
else
{
g_grouphead = curr->flink;
}
curr->flink = NULL;
}
irqrestore(flags);
}
#endif
/*****************************************************************************
* Name: group_release
*
* Description:
* Release group resources after the last member has left the group.
*
* Parameters:
* group - The group to be removed.
*
* Return Value:
* None.
*
* Assumptions:
* Called during task deletion in a safe context. No special precautions
* are required here.
*
*****************************************************************************/
static inline void group_release(FAR _TCB *tcb,
FAR struct task_group_s *group)
{
/* Free all un-reaped child exit status */
#if defined(CONFIG_SCHED_HAVE_PARENT) && defined(CONFIG_SCHED_CHILD_STATUS)
group_removechildren(group);
#endif
/* Free all file-related resources now. We really need to close files as
* soon as possible while we still have a functioning task.
*/
#if CONFIG_NFILE_DESCRIPTORS > 0 || CONFIG_NSOCKET_DESCRIPTORS > 0
(void)group_releasefiles(tcb);
#endif
/* Release all shared environment variables */
#ifndef CONFIG_DISABLE_ENVIRON
env_release(tcb);
#endif
/* Remove the group from the list of groups */
group_remove(group);
/* Release the members array */
if (group->tg_members)
{
sched_free(group->tg_members);
group->tg_members = NULL;
}
/* Release the group container itself */
sched_free(group);
}
/*****************************************************************************
* Public Functions
*****************************************************************************/
/*****************************************************************************
* Name: group_leave
*
* Description:
* Release a reference on a group. This function is called when a task or
* thread exits. It decrements the reference count on the group. If the
* reference count decrements to zero, then it frees the group and all of
* resources contained in the group.
*
* Parameters:
* tcb - The TCB of the task that is exiting.
*
* Return Value:
* None.
*
* Assumptions:
* Called during task deletion in a safe context. No special precautions
* are required here.
*
*****************************************************************************/
#ifdef HAVE_GROUP_MEMBERS
void group_leave(FAR _TCB *tcb)
{
FAR struct task_group_s *group;
DEBUGASSERT(tcb);
/* Make sure that we have a group */
group = tcb->group;
if (group)
{
/* Remove the member from group */
int ret = group_removemember(group, tcb->pid);
DEBUGASSERT(ret >= 0);
/* Is the group now empty? */
if (ret == 0)
{
/* Release all of the resource held by the task group */
group_release(tcb, group);
}
/* In any event, we can detach the group from the TCB so that we won't
* do this again.
*/
tcb->group = NULL;
}
}
#else /* HAVE_GROUP_MEMBERS */
void group_leave(FAR _TCB *tcb)
{
FAR struct task_group_s *group;
DEBUGASSERT(tcb);
/* Make sure that we have a group */
group = tcb->group;
if (group)
{
/* Yes, we have a group.. Is this the last member of the group? */
if (group->tg_nmembers > 1)
{
/* No.. just decrement the number of members in the group */
group->tg_nmembers--;
}
/* Yes.. that was the last member remaining in the group */
else
{
/* Release all of the resource held by the task group */
group_release(tcb, group);
}
/* In any event, we can detach the group from the TCB so we won't do
* this again.
*/
tcb->group = NULL;
}
}
#endif /* HAVE_GROUP_MEMBERS */
/*****************************************************************************
* Name: group_removemember
*
* Description:
* Remove a member from a group.
*
* Parameters:
* group - The group from which to remove the member.
* pid - The member to be removed.
*
* Return Value:
* On success, returns the number of members remaining in the group (>=0).
* Can fail only if the member is not found in the group. On failure,
* returns -ENOENT
*
* Assumptions:
* Called during task deletion and also from the reparenting logic, both
* in a safe context. No special precautions are required here.
*
*****************************************************************************/
#ifdef HAVE_GROUP_MEMBERS
int group_removemember(FAR struct task_group_s *group, pid_t pid)
{
int i;
DEBUGASSERT(group);
/* Find the member in the array of members and remove it */
for (i = 0; i < group->tg_nmembers; i++)
{
/* Does this member have the matching pid */
if (group->tg_members[i] == pid)
{
/* Yes.. break out of the loop. We don't do the actual
* removal here, instead we re-test i and do the adjustments
* outside of the loop. We do this because we want the
* DEBUGASSERT to work properly.
*/
break;
}
}
/* Now, test if we found the task in the array of members. */
if (i < group->tg_nmembers)
{
/* Remove the member from the array of members */
group->tg_members[i] = group->tg_members[group->tg_nmembers - 1];
group->tg_nmembers--;
return group->tg_nmembers;
}
return -ENOENT;
}
#endif /* HAVE_GROUP_MEMBERS */
#endif /* HAVE_TASK_GROUP */
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