nuttx/sched/task_create.c

/****************************************************************************
 * sched/task_create.c
 *
 *   Copyright (C) 2007-2010 Gregory Nutt. All rights reserved.
 *   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
 *
 * 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 <sys/types.h>
#include <sched.h>
#include <errno.h>
#include <debug.h>

#include <nuttx/arch.h>
#include <nuttx/kmalloc.h>

#include "os_internal.h"
#include "env_internal.h"

/****************************************************************************
 * Definitions
 ****************************************************************************/

/****************************************************************************
 * Private Type Declarations
 ****************************************************************************/

/****************************************************************************
 * Global Variables
 ****************************************************************************/

/****************************************************************************
 * Private Variables
 ****************************************************************************/

/****************************************************************************
 * Private Function Prototypes
 ****************************************************************************/

/****************************************************************************
 * Private Functions
 ****************************************************************************/

/****************************************************************************
 * Name: task_create
 *
 * Description:
 *   This function creates and activates a new task with a
 *   specified priority and returns its system-assigned ID.
 *
 *   The entry address entry is the address of the "main"
 *   function of the task.  This function will be called once
 *   the C environment has been set up.  The specified
 *   function will be called with four arguments.  Should
 *   the specified routine return, a call to exit() will
 *   automatically be made.
 *
 *   Note that four (and only four) arguments must be passed for
 *   the spawned functions.
 *
 * Input Parameters:
 *   name       - Name of the new task
 *   priority   - Priority of the new task
 *   stack_size - size (in bytes) of the stack needed
 *   entry      - Entry point of a new task
 *   arg        - A pointer to an array of input parameters.
 *                Up to  CONFIG_MAX_TASK_ARG parameters may
 *                be provided.  If fewer than CONFIG_MAX_TASK_ARG
 *                parameters are passed, the list should be
 *                terminated with a NULL argv[] value.
 *                If no parameters are required, argv may be
 *                NULL.
 *
 * Return Value:
 *   Returns the non-zero process ID of the new task or
 *   ERROR if memory is insufficient or the task cannot be
 *   created (errno is not set).
 *
 ****************************************************************************/

#ifndef CONFIG_CUSTOM_STACK
int task_create(const char *name, int priority,
                int stack_size, main_t entry, const char *argv[])
#else
int task_create(const char *name, int priority,
                main_t entry, const char *argv[])
#endif
{
  FAR _TCB *tcb;
  int status;
  pid_t pid;

  /* Allocate a TCB for the new task. */

  tcb = (FAR _TCB*)kzalloc(sizeof(_TCB));
  if (!tcb)
    {
      errno = ENOMEM;
      return ERROR;
    }

  /* Associate file descriptors with the new task */

#if CONFIG_NFILE_DESCRIPTORS > 0 || CONFIG_NSOCKET_DESCRIPTORS > 0
  if (sched_setuptaskfiles(tcb) != OK)
    {
      sched_releasetcb(tcb);
      return ERROR;
    }
#endif

  /* Clone the parent's task environment */

  (void)env_dup(tcb);

  /* Allocate the stack for the TCB */

#ifndef CONFIG_CUSTOM_STACK
  status = up_create_stack(tcb, stack_size);
  if (status != OK)
    {
      sched_releasetcb(tcb);
      return ERROR;
    }
#endif

  /* Initialize the task control block */

  status = task_schedsetup(tcb, priority, task_start, entry);
  if (status != OK)
    {
      sched_releasetcb(tcb);
      return ERROR;
    }

  /* Setup to pass parameters to the new task */

  (void)task_argsetup(tcb, name, argv);

  /* Get the assigned pid before we start the task */

  pid = (int)tcb->pid;

  /* Activate the task */

  status = task_activate(tcb);
  if (status != OK)
    {
      dq_rem((FAR dq_entry_t*)tcb, (dq_queue_t*)&g_inactivetasks);
      sched_releasetcb(tcb);
      return ERROR;
    }

  return pid;
}