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px4-firmware/nuttx/sched/group_create.c

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/*****************************************************************************
* sched/group_create.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 "group_internal.h"
#include "env_internal.h"
#ifdef HAVE_TASK_GROUP
/*****************************************************************************
* Pre-processor Definitions
*****************************************************************************/
/* Is this worth making a configuration option? */
#define GROUP_INITIAL_MEMBERS 4
/*****************************************************************************
* Private Types
*****************************************************************************/
/*****************************************************************************
* Private Data
*****************************************************************************/
/* This is counter that is used to generate unique task group IDs */
#ifdef HAVE_GROUP_MEMBERS
static gid_t g_gidcounter;
#endif
/*****************************************************************************
* Public Data
*****************************************************************************/
/* This is the head of a list of all group members */
#ifdef HAVE_GROUP_MEMBERS
FAR struct task_group_s *g_grouphead;
#endif
/*****************************************************************************
* Private Functions
*****************************************************************************/
/*****************************************************************************
* Name: group_assigngid
*
* Description:
* Create a unique group ID.
*
* Parameters:
* tcb - The tcb in need of the task group.
*
* Return Value:
* None
*
* Assumptions:
* Called during task creation in a safe context. No special precautions
* are required here.
*
*****************************************************************************/
#ifdef HAVE_GROUP_MEMBERS
void group_assigngid(FAR struct task_group_s *group)
{
irqstate_t flags;
gid_t gid;
/* Pre-emption should already be enabled, but lets be paranoid careful */
sched_lock();
/* Loop until we create a unique ID */
for (;;)
{
/* Increment the ID counter. This is global data so be extra paraoid. */
flags = irqsave();
gid = ++g_gidcounter;
/* Check for overflow */
if (gid <= 0)
{
g_gidcounter = 1;
irqrestore(flags);
}
else
{
/* Does a task group with this ID already exist? */
irqrestore(flags);
if (group_find(gid) == NULL)
{
/* Now assign this ID to the group and return */
group->tg_gid = gid;
sched_unlock();
return;
}
}
}
}
#endif /* HAVE_GROUP_MEMBERS */
/*****************************************************************************
* Public Functions
*****************************************************************************/
/*****************************************************************************
* Name: group_allocate
*
* Description:
* Create and a new task group structure for the specified TCB. This
* function is called as part of the task creation sequence. The structure
* allocated and zered, but otherwise uninitialized. The full creation
* of the group of a two step process: (1) First, this function allocates
* group structure early in the task creation sequence in order to provide a
* group container, then (2) group_initialize() is called to set up the
* group membership.
*
* Parameters:
* tcb - The tcb in need of the task group.
*
* Return Value:
* 0 (OK) on success; a negated errno value on failure.
*
* Assumptions:
* Called during task creation in a safe context. No special precautions
* are required here.
*
*****************************************************************************/
int group_allocate(FAR _TCB *tcb)
{
int ret;
DEBUGASSERT(tcb && !tcb->group);
/* Allocate the group structure and assign it to the TCB */
tcb->group = (FAR struct task_group_s *)kzalloc(sizeof(struct task_group_s));
if (!tcb->group)
{
return -ENOMEM;
}
/* Assign the group a unique ID. If g_gidcounter were to wrap before we
* finish with task creation, that would be a problem.
*/
#ifdef HAVE_GROUP_MEMBERS
group_assigngid(tcb->group);
#endif
/* Duplicate the parent tasks envionment */
ret = env_dup(tcb->group);
if (ret < 0)
{
kfree(tcb->group);
tcb->group = NULL;
return ret;
}
return OK;
}
/*****************************************************************************
* Name: group_initialize
*
* Description:
* Add the task as the initial member of the group. The full creation of
* the group of a two step process: (1) First, this group structure is
* allocated by group_allocate() early in the task creation sequence, then
* (2) this function is called to set up the initial group membership.
*
* Parameters:
* tcb - The tcb in need of the task group.
*
* Return Value:
* 0 (OK) on success; a negated errno value on failure.
*
* Assumptions:
* Called during task creation in a safe context. No special precautions
* are required here.
*
*****************************************************************************/
int group_initialize(FAR _TCB *tcb)
{
FAR struct task_group_s *group;
#ifdef HAVE_GROUP_MEMBERS
irqstate_t flags;
#endif
DEBUGASSERT(tcb && tcb->group);
group = tcb->group;
#ifdef HAVE_GROUP_MEMBERS
/* Allocate space to hold GROUP_INITIAL_MEMBERS members of the group */
group->tg_members = (FAR pid_t *)kmalloc(GROUP_INITIAL_MEMBERS*sizeof(pid_t));
if (!group->tg_members)
{
free(group);
return -ENOMEM;
}
/* Assign the PID of this new task as a member of the group*/
group->tg_members[0] = tcb->pid;
/* Initialize the non-zero elements of group structure and assign it to
* the tcb.
*/
group->tg_mxmembers = GROUP_INITIAL_MEMBERS; /* Number of members in allocation */
/* Add the initialized entry to the list of groups */
flags = irqsave();
group->flink = g_grouphead;
g_grouphead = group;
irqrestore(flags);
#endif
group->tg_nmembers = 1; /* Number of members in the group */
return OK;
}
#endif /* HAVE_TASK_GROUP */
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