Linux学习笔记：pthread_getschedparam函数

而在Linux2.6的内核中调用该函数，第一个参数指定为0，则系统宕，原因是收到了SIGSEVG信号，也就是说程序访问的非法的地址。查了一晚上，应该是找到原因了。

首先看pthread_getschedparam函数的定义。

/*
* sched_getschedparam.c
*
* Description:
* POSIX thread functions that deal with thread scheduling.
*
* --------------------------------------------------------------------------
*
*      Pthreads-win32 - POSIX Threads Library for Win32
*      Copyright(C) 1998 John E. Bossom
*      Copyright(C) 1999,2005 Pthreads-win32 contributors
*
*      Contact Email: [email protected]
*
*      The current list of contributors is contained
*      in the file CONTRIBUTORS included with the source
*      code distribution. The list can also be seen at the
*      following World Wide Web location:
*      http://sources.RedHat.com/pthreads-win32/contributors.html
*
*      This library is free software; you can redistribute it and/or
*      modify it under the terms of the GNU Lesser General Public
*      License as published by the Free Software Foundation; either
*      version 2 of the License, or (at your option) any later version.
*
*      This library is distributed in the hope that it will be useful,
*      but WITHOUT ANY WARRANTY; without even the implied warranty of
*      MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
*      Lesser General Public License for more details.
*
*      You should have received a copy of the GNU Lesser General Public
*      License along with this library in the file COPYING.LIB;
*     if not, write to the Free Software Foundation, Inc.,
*      59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
*/

#include "pthread.h"
#include "implement.h"
#include "sched.h"

int
pthread_getschedparam (pthread_t thread, int *policy,
       struct sched_param *param)
{
  int result;

  /* Validate the thread id. */
  result = pthread_kill (thread, 0);
  if (0 != result)
    {
      return result;
    }

  /*
   * Validate the policy and param args.
  * Check that a policy constant wasn't passed rather than &policy.
   */
  if (policy <= (int *) SCHED_MAX || param == NULL)
    {
      return EINVAL;
    }

  /* Fill out the policy. */
  *policy = SCHED_OTHER;

  /*
   * This function must return the priority value set by
   * the most recent pthread_setschedparam() or pthread_create()
   * for the target thread. It must not return the actual thread
   * priority as altered by any system priority adjustments etc.
   */
  param->sched_priority = ((ptw32_thread_t *)thread.p)->sched_priority;

  return 0;
}
函数首先调用了pthread_kill函数，在查一下pthread_kill的定义。

从中可以看到，在pthread_kill中，

if <font face="Courier New">(DEBUGGING_P && INVALID_TD_P (pd)) </font>

首先进行了判断，但是很有可能DEBUGGING_P宏没定义，所以程序就跳了过去，

然后再