nptl/pthread_clock_settime.c

   1 /* Copyright (C) 2001-2015 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 <libc-internal.h>
  22 #include "pthreadP.h"
  23
  24
  25 #if HP_TIMING_AVAIL
  26 int
  27 __pthread_clock_settime (clockid_t clock_id, hp_timing_t offset)
  28 {
  29   /* This is the ID of the thread we are looking for.  */
  30   pid_t tid = ((unsigned int) clock_id) >> CLOCK_IDFIELD_SIZE;
  31
  32   /* Compute the offset since the start time of the process.  */
  33   if (tid == 0 || tid == THREAD_GETMEM (THREAD_SELF, tid))
  34     /* Our own clock.  */
  35     THREAD_SETMEM (THREAD_SELF, cpuclock_offset, offset);
  36   else
  37     {
  38       /* This is more complicated.  We have to locate the thread based
  39          on the ID.  This means walking the list of existing
  40          threads.  */
  41       struct pthread *thread = __find_thread_by_id (tid);
  42       if (thread == NULL)
  43         {
  44           __set_errno (EINVAL);
  45           return -1;
  46         }
  47
  48       /* There is a race here.  The thread might terminate and the stack
  49          become unusable.  But this is the user's problem.  */
  50       thread->cpuclock_offset = offset;
  51     }
  52
  53   return 0;
  54 }
  55 #endif