nptl/pthread_clock_settime.c

   1 /* Copyright (C) 2001-2017 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3
   4    The GNU C Library is free software; you can redistribute it and/or
   5    modify it under the terms of the GNU Lesser General Public License as
   6    published by the Free Software Foundation; either version 2.1 of the
   7    License, or (at your option) any later version.
   8
   9    The GNU C Library is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12    Lesser General Public License for more details.
  13
  14    You should have received a copy of the GNU Lesser General Public
  15    License along with the GNU C Library; see the file COPYING.LIB.  If
  16    not, see <http://www.gnu.org/licenses/>.  */
  17
  18 #include <errno.h>
  19 #include <stdlib.h>
  20 #include <time.h>
  21 #include "pthreadP.h"
  22
  23
  24 #if HP_TIMING_AVAIL
  25 int
  26 __pthread_clock_settime (clockid_t clock_id, hp_timing_t offset)
  27 {
  28   /* This is the ID of the thread we are looking for.  */
  29   pid_t tid = ((unsigned int) clock_id) >> CLOCK_IDFIELD_SIZE;
  30
  31   /* Compute the offset since the start time of the process.  */
  32   if (tid == 0 || tid == THREAD_GETMEM (THREAD_SELF, tid))
  33     /* Our own clock.  */
  34     THREAD_SETMEM (THREAD_SELF, cpuclock_offset, offset);
  35   else
  36     {
  37       /* This is more complicated.  We have to locate the thread based
  38          on the ID.  This means walking the list of existing
  39          threads.  */
  40       struct pthread *thread = __find_thread_by_id (tid);
  41       if (thread == NULL)
  42         {
  43           __set_errno (EINVAL);
  44           return -1;
  45         }
  46
  47       /* There is a race here.  The thread might terminate and the stack
  48          become unusable.  But this is the user's problem.  */
  49       thread->cpuclock_offset = offset;
  50     }
  51
  52   return 0;
  53 }
  54 #endif