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incubator-nuttx/sched/group/group_leave.c

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/****************************************************************************
* sched/group/group_leave.c
*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership. The
* ASF licenses this file to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance with the
* License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations
* under the License.
*
****************************************************************************/
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/config.h>
#include <sched.h>
#include <assert.h>
#include <errno.h>
#include <debug.h>
#include <nuttx/irq.h>
#include <nuttx/fs/fs.h>
#include <nuttx/net/net.h>
#include <nuttx/sched.h>
#ifdef CONFIG_BINFMT_LOADABLE
# include <nuttx/binfmt/binfmt.h>
#endif
#include "environ/environ.h"
#include "signal/signal.h"
#include "pthread/pthread.h"
#include "mqueue/mqueue.h"
#include "group/group.h"
#include "tls/tls.h"
/****************************************************************************
* Private Functions
****************************************************************************/
/****************************************************************************
* Name: group_remove
*
* Description:
* Remove a group from the list of groups.
*
* Input Parameters:
* group - The group to be removed.
*
* Returned Value:
* None.
*
* Assumptions:
* Called during task deletion in a safe context. No special precautions
* are required here.
*
****************************************************************************/
#if defined(HAVE_GROUP_MEMBERS)
static 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 = enter_critical_section();
/* 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;
}
leave_critical_section(flags);
}
#endif
/****************************************************************************
* Name: group_release
*
* Description:
* Release group resources after the last member has left the group.
*
* Input Parameters:
* group - The group to be removed.
*
* Returned Value:
* None.
*
* Assumptions:
* Called during task deletion in a safe context. No special precautions
* are required here.
*
****************************************************************************/
static inline void group_release(FAR struct task_group_s *group)
{
task_uninit_info(group);
#if defined(CONFIG_SCHED_HAVE_PARENT) && defined(CONFIG_SCHED_CHILD_STATUS)
/* Free all un-reaped child exit status */
group_remove_children(group);
#endif
/* Release pending signals */
nxsig_release(group);
#ifndef CONFIG_DISABLE_PTHREAD
/* Release pthread resources */
pthread_release(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.
*/
/* Free resources held by the file descriptor list */
files_releaselist(&group->tg_filelist);
#ifndef CONFIG_DISABLE_ENVIRON
/* Release all shared environment variables */
env_release(group);
#endif
/* Destroy the mm_map list */
mm_map_destroy(&group->tg_mm_map);
#if defined(HAVE_GROUP_MEMBERS)
/* Remove the group from the list of groups */
group_remove(group);
#endif
#ifdef HAVE_GROUP_MEMBERS
/* Release the members array */
if (group->tg_members)
{
kmm_free(group->tg_members);
group->tg_members = NULL;
}
#endif
#ifdef CONFIG_BINFMT_LOADABLE
/* If the exiting task was loaded into RAM from a file, then we need to
* lease all of the memory resource when the last thread exits the task
* group.
*/
if (group->tg_bininfo != NULL)
{
binfmt_exit(group->tg_bininfo);
group->tg_bininfo = NULL;
}
#endif
/* Mark the group as deleted now */
group->tg_flags |= GROUP_FLAG_DELETED;
/* Then drop the group freeing the allocated memory */
group_drop(group);
}
/****************************************************************************
* Name: group_removemember
*
* Description:
* Remove a member from a group.
*
* Input Parameters:
* group - The group from which to remove the member.
* pid - The member to be removed.
*
* Returned 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
static inline void group_removemember(FAR struct task_group_s *group,
pid_t pid)
{
irqstate_t flags;
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)
{
/* Remove the member from the array of members. This must be an
* atomic operation because the member array may be accessed from
* interrupt handlers (read-only).
*/
flags = enter_critical_section();
group->tg_members[i] = group->tg_members[group->tg_nmembers - 1];
group->tg_nmembers--;
leave_critical_section(flags);
}
}
}
#endif /* HAVE_GROUP_MEMBERS */
/****************************************************************************
* 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.
*
* Input Parameters:
* tcb - The TCB of the task that is exiting.
*
* Returned 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 struct tcb_s *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. This function may be called
* during certain error handling before the PID has been
* added to the group. In this case tcb->pid will be uninitialized
* group_removemember() will fail.
*/
group_removemember(group, tcb->pid);
/* Have all of the members left the group? */
if (group->tg_nmembers == 0)
{
/* Yes.. Release all of the resource held by the task group */
group_release(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 struct tcb_s *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(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_drop
*
* Description:
* Release the group's memory. This function is called whenever a reference
* to the group structure is released. It is not dependent on member count,
* but rather external references, which include:
* - Waiter list for waitpid()
*
* Input Parameters:
* group - The group that is to be dropped
*
* Returned Value:
* None.
*
* Assumptions:
* Called during task deletion or context switch in a safe context. No
* special precautions are required here.
*
****************************************************************************/
void group_drop(FAR struct task_group_s *group)
{
#if defined(CONFIG_SCHED_WAITPID) && !defined(CONFIG_SCHED_HAVE_PARENT)
/* If there are threads waiting for this group to be freed, then we cannot
* yet free the memory resources. Instead just mark the group deleted
* and wait for those threads complete their waits.
*/
if (group->tg_nwaiters > 0)
{
/* Hold the group still */
sinfo("Keep group %p (waiters > 0)\n", group);
}
else
#endif
/* Finally, if no one needs the group and it has been deleted, remove it */
if (group->tg_flags & GROUP_FLAG_DELETED)
{
/* Release the group container itself */
kmm_free(group);
}
}
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