text: /****************************************************************************
   *  arch/x86/src/common/up_releasestack.c
   *
   *   Copyright (C) 2011, 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 <debug.h>
  
  #include <nuttx/arch.h>
  #include <nuttx/kmalloc.h>
  
  #include "up_internal.h"
  
  /****************************************************************************
   * Private Types
   ****************************************************************************/
  
  /****************************************************************************
   * Private Function Prototypes
   ****************************************************************************/
  
  /****************************************************************************
   * Public Functions
   ****************************************************************************/
  
  /****************************************************************************
   * Name: up_release_stack
   *
   * Description:
   *   A task has been stopped. Free all stack related resources retained in
   *   the defunct TCB.
   *
   * Input Parmeters
   *   - dtcb:  The TCB containing information about the stack to be released
   *   - ttype:  The thread type.  This may be one of following (defined in
   *     include/nuttx/sched.h):
   *
   *       TCB_FLAG_TTYPE_TASK     Normal user task
   *       TCB_FLAG_TTYPE_PTHREAD  User pthread
   *       TCB_FLAG_TTYPE_KERNEL   Kernel thread
   *
   *     This thread type is normally available in the flags field of the TCB,
   *     however, there are certain error recovery contexts where the TCB may
   *     not be fully initialized when up_release_stack is called.
   *
   *     If CONFIG_BUILD_KERNEL is defined, then this thread type may affect
   *     how the stack is freed.  For example, kernel thread stacks may have
   *     been allocated from protected kernel memory.  Stacks for user tasks
   *     and threads must have come from memory that is accessible to user
   *     code.
   *
   * Returned Value:
   *   None
   *
   ****************************************************************************/
  
  void up_release_stack(FAR struct tcb_s *dtcb, uint8_t ttype)
  {
    /* Is there a stack allocated? */
  
    if (dtcb->stack_alloc_ptr)
      {
  #if defined(CONFIG_BUILD_KERNEL) && defined(CONFIG_MM_KERNEL_HEAP)
        /* Use the kernel allocator if this is a kernel thread */
  
        if (ttype == TCB_FLAG_TTYPE_KERNEL)
          {
            sched_kfree(dtcb->stack_alloc_ptr);
          }
        else
  #endif
          {
            /* Use the user-space allocator if this is a task or pthread */
  
            sched_ufree(dtcb->stack_alloc_ptr);
          }
  
        /* Mark the stack freed */
  
        dtcb->stack_alloc_ptr = NULL;
      }
  
    /* The size of the allocated stack is now zero */
  
    dtcb->adj_stack_size = 0;
  }
  