nptl/pthread_setschedprio.c

   1 /* Copyright (C) 2002-2017 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3    Contributed by Ulrich Drepper <drepper@redhat.com>, 2002.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <http://www.gnu.org/licenses/>.  */
  18
  19 #include <errno.h>
  20 #include <sched.h>
  21 #include <string.h>
  22 #include <sched.h>
  23 #include "pthreadP.h"
  24 #include <lowlevellock.h>
  25
  26
  27 int
  28 pthread_setschedprio (pthread_t threadid, int prio)
  29 {
  30   struct pthread *pd = (struct pthread *) threadid;
  31
  32   /* Make sure the descriptor is valid.  */
  33   if (INVALID_TD_P (pd))
  34     /* Not a valid thread handle.  */
  35     return ESRCH;
  36
  37   int result = 0;
  38   struct sched_param param;
  39   param.sched_priority = prio;
  40
  41   /* See CREATE THREAD NOTES in nptl/pthread_create.c.  */
  42   lll_lock (pd->lock, LLL_PRIVATE);
  43
  44   /* If the thread should have higher priority because of some
  45      PTHREAD_PRIO_PROTECT mutexes it holds, adjust the priority.  */
  46   if (__builtin_expect (pd->tpp != NULL, 0) && pd->tpp->priomax > prio)
  47     param.sched_priority = pd->tpp->priomax;
  48
  49   /* Try to set the scheduler information.  */
  50   if (__glibc_unlikely (sched_setparam (pd->tid, &param) == -1))
  51     result = errno;
  52   else
  53     {
  54       /* We succeeded changing the kernel information.  Reflect this
  55          change in the thread descriptor.  */
  56       param.sched_priority = prio;
  57       memcpy (&pd->schedparam, &param, sizeof (struct sched_param));
  58       pd->flags |= ATTR_FLAG_SCHED_SET;
  59     }
  60
  61   lll_unlock (pd->lock, LLL_PRIVATE);
  62
  63   return result;
  64 }