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