nptl/sysdeps/unix/sysv/linux/pthread_getcpuclockid.c

   1 /* pthread_getcpuclockid -- Get POSIX clockid_t for a pthread_t.  Linux version
   2    Copyright (C) 2000,2001,2002,2003,2004,2005 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   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 License as
   7    published by the Free Software Foundation; either version 2.1 of the
   8    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; see the file COPYING.LIB.  If not,
  17    write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  18    Boston, MA 02111-1307, USA.  */
  19
  20 #include <errno.h>
  21 #include <pthreadP.h>
  22 #include <sys/time.h>
  23 #include <tls.h>
  24 #include <kernel-features.h>
  25 #include <kernel-posix-cpu-timers.h>
  26
  27
  28 #if !(__ASSUME_POSIX_CPU_TIMERS > 0)
  29 int __libc_missing_posix_cpu_timers attribute_hidden;
  30 #endif
  31 #if !(__ASSUME_POSIX_TIMERS > 0)
  32 int __libc_missing_posix_timers attribute_hidden;
  33 #endif
  34
  35 int
  36 pthread_getcpuclockid (threadid, clockid)
  37      pthread_t threadid;
  38      clockid_t *clockid;
  39 {
  40   struct pthread *pd = (struct pthread *) threadid;
  41
  42   /* Make sure the descriptor is valid.  */
  43   if (INVALID_TD_P (pd))
  44     /* Not a valid thread handle.  */
  45     return ESRCH;
  46
  47 #ifdef __NR_clock_getres
  48   /* The clockid_t value is a simple computation from the TID.
  49      But we do a clock_getres call to validate it if we aren't
  50      yet sure we have the kernel support.  */
  51
  52   const clockid_t tidclock = MAKE_THREAD_CPUCLOCK (pd->tid, CPUCLOCK_SCHED);
  53
  54 # if !(__ASSUME_POSIX_CPU_TIMERS > 0)
  55 #  if !(__ASSUME_POSIX_TIMERS > 0)
  56   if (__libc_missing_posix_timers && !__libc_missing_posix_cpu_timers)
  57     __libc_missing_posix_cpu_timers = 1;
  58 #  endif
  59   if (!__libc_missing_posix_cpu_timers)
  60     {
  61       INTERNAL_SYSCALL_DECL (err);
  62       int r = INTERNAL_SYSCALL (clock_getres, err, 2, tidclock, NULL);
  63       if (!INTERNAL_SYSCALL_ERROR_P (r, err))
  64 # endif
  65         {
  66           *clockid = tidclock;
  67           return 0;
  68         }
  69
  70 # if !(__ASSUME_POSIX_CPU_TIMERS > 0)
  71 #  if !(__ASSUME_POSIX_TIMERS > 0)
  72       if (INTERNAL_SYSCALL_ERRNO (r, err) == ENOSYS)
  73         {
  74           /* The kernel doesn't support these calls at all.  */
  75           __libc_missing_posix_timers = 1;
  76           __libc_missing_posix_cpu_timers = 1;
  77         }
  78       else
  79 #  endif
  80         if (INTERNAL_SYSCALL_ERRNO (r, err) == EINVAL)
  81           {
  82             /* The kernel doesn't support these clocks at all.  */
  83             __libc_missing_posix_cpu_timers = 1;
  84           }
  85       else
  86         return INTERNAL_SYSCALL_ERRNO (r, err);
  87     }
  88 # endif
  89 #endif
  90
  91 #ifdef CLOCK_THREAD_CPUTIME_ID
  92   /* We need to store the thread ID in the CLOCKID variable together
  93      with a number identifying the clock.  We reserve the low 3 bits
  94      for the clock ID and the rest for the thread ID.  This is
  95      problematic if the thread ID is too large.  But 29 bits should be
  96      fine.
  97
  98      If some day more clock IDs are needed the ID part can be
  99      enlarged.  The IDs are entirely internal.  */
 100   if (pd->tid >= 1 << (8 * sizeof (*clockid) - CLOCK_IDFIELD_SIZE))
 101     return ERANGE;
 102
 103   /* Store the number.  */
 104   *clockid = CLOCK_THREAD_CPUTIME_ID | (pd->tid << CLOCK_IDFIELD_SIZE);
 105
 106   return 0;
 107 #else
 108   /* We don't have a timer for that.  */
 109   return ENOENT;
 110 #endif
 111 }