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px4-firmware/nuttx/sched/task_childstatus.c

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/*****************************************************************************
* sched/task_childstatus.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 <errno.h>
#include <debug.h>
#include "os_internal.h"
#if defined(CONFIG_SCHED_HAVE_PARENT) && defined(CONFIG_SCHED_CHILD_STATUS)
/*****************************************************************************
* Pre-processor Definitions
*****************************************************************************/
/* Note that there cannot be more that CONFIG_MAX_TASKS tasks in total.
* However, the number of child status structures may need to be significantly
* larger because this number includes the maximum number of tasks that are
* running PLUS the number of tasks that have exit'ed without having their
* exit status reaped (via wait(), waitid(), or waitpid()).
*
* Obviously, if tasks spawn children indefinitely and never have the exit
* status reaped, then you have a memory leak!
*/
#if !defined(CONFIG_PREALLOC_CHILDSTATUS) || CONFIG_PREALLOC_CHILDSTATUS == 0
# undef CONFIG_PREALLOC_CHILDSTATUS
# define CONFIG_PREALLOC_CHILDSTATUS (2*CONFIG_MAX_TASKS)
#endif
#ifndef CONFIG_DEBUG
# undef CONFIG_DEBUG_CHILDSTATUS
#endif
/*****************************************************************************
* Private Types
*****************************************************************************/
/* Globals are maintained in a structure to minimize name collisions. */
struct child_pool_s
{
struct child_status_s alloc[CONFIG_PREALLOC_CHILDSTATUS];
FAR struct child_status_s *freelist;
};
/*****************************************************************************
* Private Data
*****************************************************************************/
static struct child_pool_s g_child_pool;
/*****************************************************************************
* Private Functions
*****************************************************************************/
/*****************************************************************************
* Name: task_dumpchildren
*
* Description:
* Dump all of the children when the part TCB list is modified.
*
* Parameters:
* tcb - The parent TCB.
*
* Return Value:
* None.
*
* Assumptions:
* Called early in initialization. No special precautions are required.
*
*****************************************************************************/
#ifdef CONFIG_DEBUG_CHILDSTATUS
static void task_dumpchildren(FAR _TCB *tcb, FAR const char *msg)
{
FAR struct child_status_s *child;
int i;
dbg("Parent TCB=%p: %s\n", tcb, msg);
for (i = 0, child = tcb->children; child; i++, child = child->flink)
{
dbg(" %d. ch_flags=%02x ch_pid=%d ch_status=%d\n",
i, child->ch_flags, child->ch_pid, child->ch_status);
}
}
#else
# task_dumpchildren(t,m)
#endif
/*****************************************************************************
* Public Functions
*****************************************************************************/
/*****************************************************************************
* Name: task_initialize
*
* Description:
* Initialize task related status. At present, this includes only the
* initialize of the child status pool.
*
* Parameters:
* None.
*
* Return Value:
* None.
*
* Assumptions:
* Called early in initialization. No special precautions are required.
*
*****************************************************************************/
void task_initialize(void)
{
FAR struct child_status_s *curr;
FAR struct child_status_s *prev;
int i;
/* Save all of the child status structures in a free list */
prev = &g_child_pool.alloc[0];
g_child_pool.freelist = prev;
for (i = 0; i < CONFIG_PREALLOC_CHILDSTATUS; i++)
{
curr = &g_child_pool.alloc[i];
prev->flink = curr;
prev = curr;
}
}
/*****************************************************************************
* Name: task_allocchild
*
* Description:
* Allocate a child status structure by removing the next entry from a
* free list.
*
* Parameters:
* None.
*
* Return Value:
* On success, a non-NULL pointer to a child status structure. NULL is
* returned if there are no remaining, pre-allocated child status structures.
*
* Assumptions:
* Called during task creation in a safe context. No special precautions
* are required here.
*
*****************************************************************************/
FAR struct child_status_s *task_allocchild(void)
{
FAR struct child_status_s *ret;
/* Return the status block at the head of the free list */
ret = g_child_pool.freelist;
if (ret)
{
g_child_pool.freelist = ret->flink;
ret->flink = NULL;
}
return ret;
}
/*****************************************************************************
* Name: task_freechild
*
* Description:
* Release a child status structure by returning it to a free list.
*
* Parameters:
* status - The child status structure to be freed.
*
* Return Value:
* None.
*
* Assumptions:
* Called during task creation in a safe context. No special precautions
* are required here.
*
*****************************************************************************/
void task_freechild(FAR struct child_status_s *child)
{
/* Return the child status structure to the free list */
if (child)
{
child->flink = g_child_pool.freelist;
g_child_pool.freelist = child;
}
}
/*****************************************************************************
* Name: task_addchild
*
* Description:
* Add a child status structure in the given TCB.
*
* Parameters:
* tcb - The TCB of the parent task to containing the child status.
* child - The structure to be added
*
* Return Value:
* N
*
* Assumptions:
* Called during task creation processing in a safe context. No special
* precautions are required here.
*
*****************************************************************************/
void task_addchild(FAR _TCB *tcb, FAR struct child_status_s *child)
{
/* Add the entry into the TCB list of children */
child->flink = tcb->children;
tcb->children = child;
task_dumpchildren(tcb, "task_addchild");
}
/*****************************************************************************
* Name: task_findchild
*
* Description:
* Find a child status structure in the given TCB. A reference to the
* child structure is returned, but the child remains the the TCB's list
* of children.
*
* Parameters:
* tcb - The TCB of the parent task to containing the child status.
* pid - The ID of the child to find.
*
* Return Value:
* On success, a non-NULL pointer to a child status structure. NULL is
* returned if there is child status structure for that pid in the TCB.
*
* Assumptions:
* Called during SIGCHLD processing in a safe context. No special precautions
* are required here.
*
*****************************************************************************/
FAR struct child_status_s *task_findchild(FAR _TCB *tcb, pid_t pid)
{
FAR struct child_status_s *child;
/* Find the status structure with the matching PID */
for (child = tcb->children; child; child = child->flink)
{
if (child->ch_pid == pid)
{
return child;
}
}
return NULL;
}
/*****************************************************************************
* Name: task_removechild
*
* Description:
* Remove one child structure from the TCB. The child is removed, but is
* not yet freed. task_freechild must be called in order to free the child
* status structure.
*
* Parameters:
* tcb - The TCB of the parent task to containing the child status.
* pid - The ID of the child to find.
*
* Return Value:
* On success, a non-NULL pointer to a child status structure. NULL is
* returned if there is child status structure for that pid in the TCB.
*
* Assumptions:
* Called during SIGCHLD processing in a safe context. No special precautions
* are required here.
*
*****************************************************************************/
FAR struct child_status_s *task_removechild(FAR _TCB *tcb, pid_t pid)
{
FAR struct child_status_s *curr;
FAR struct child_status_s *prev;
/* Find the status structure with the matching PID */
for (prev = NULL, curr = tcb->children;
curr;
prev = curr, curr = curr->flink)
{
if (curr->ch_pid == pid)
{
break;
}
}
/* Did we find it? If so, remove it from the TCB. */
if (curr)
{
/* Do we remove it from mid-list? Or from the head of the list? */
if (prev)
{
prev->flink = curr->flink;
}
else
{
tcb->children = curr->flink;
}
curr->flink = NULL;
task_dumpchildren(tcb, "task_removechild");
}
return curr;
}
/*****************************************************************************
* Name: task_removechildren
*
* Description:
* Remove and free all child structure from the TCB.
*
* Parameters:
* tcb - The TCB of the parent task to containing the child status.
*
* Return Value:
* None.
*
* Assumptions:
* Called during task exit processing in a safe context. No special
* precautions are required here.
*
*****************************************************************************/
void task_removechildren(FAR _TCB *tcb)
{
FAR struct child_status_s *curr;
FAR struct child_status_s *next;
/* Remove all child structures for the TCB and return them to the freelist */
for (curr = tcb->children; curr; curr = next)
{
next = curr->flink;
task_freechild(curr);
}
tcb->children = NULL;
task_dumpchildren(tcb, "task_removechildren");
}
#endif /* CONFIG_SCHED_HAVE_PARENT && CONFIG_SCHED_CHILD_STATUS */
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