linuxthreads/sysdeps/pthread/getcpuclockid.c

   1 /* pthread_getcpuclockid -- Get POSIX clockid_t for a pthread_t.  Linux version
   2    Copyright (C) 2000, 2001, 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 <pthread.h>
  22 #include <sys/time.h>
  23 #include <time.h>
  24 #include <internals.h>
  25 #include <spinlock.h>
  26 #include <kernel-features.h>
  27 #include <kernel-posix-cpu-timers.h>
  28
  29
  30 #if !(__ASSUME_POSIX_CPU_TIMERS > 0)
  31 int __libc_missing_posix_cpu_timers attribute_hidden;
  32 #endif
  33 #if !(__ASSUME_POSIX_TIMERS > 0)
  34 int __libc_missing_posix_timers attribute_hidden;
  35 #endif
  36
  37 int
  38 pthread_getcpuclockid (pthread_t thread_id, clockid_t *clock_id)
  39 {
  40 #ifdef __NR_clock_getres
  41   pthread_handle handle = thread_handle(thread_id);
  42   int pid;
  43
  44   __pthread_lock (&handle->h_lock, NULL);
  45   if (nonexisting_handle (handle, thread_id))
  46     {
  47       __pthread_unlock (&handle->h_lock);
  48       return ESRCH;
  49     }
  50   pid = handle->h_descr->p_pid;
  51   __pthread_unlock (&handle->h_lock);
  52
  53   /* The clockid_t value is a simple computation from the PID.
  54      But we do a clock_getres call to validate it if we aren't
  55      yet sure we have the kernel support.  */
  56
  57   const clockid_t pidclock = MAKE_PROCESS_CPUCLOCK (pid, CPUCLOCK_SCHED);
  58
  59 # if !(__ASSUME_POSIX_CPU_TIMERS > 0)
  60 #  if !(__ASSUME_POSIX_TIMERS > 0)
  61   if (__libc_missing_posix_timers && !__libc_missing_posix_cpu_timers)
  62     __libc_missing_posix_cpu_timers = 1;
  63 #  endif
  64   if (!__libc_missing_posix_cpu_timers)
  65     {
  66       INTERNAL_SYSCALL_DECL (err);
  67       int r = INTERNAL_SYSCALL (clock_getres, err, 2, pidclock, NULL);
  68       if (!INTERNAL_SYSCALL_ERROR_P (r, err))
  69 # endif
  70         {
  71           *clock_id = pidclock;
  72           return 0;
  73         }
  74
  75 # if !(__ASSUME_POSIX_CPU_TIMERS > 0)
  76 #  if !(__ASSUME_POSIX_TIMERS > 0)
  77       if (INTERNAL_SYSCALL_ERRNO (r, err) == ENOSYS)
  78         {
  79           /* The kernel doesn't support these calls at all.  */
  80           __libc_missing_posix_timers = 1;
  81           __libc_missing_posix_cpu_timers = 1;
  82         }
  83       else
  84 #  endif
  85         if (INTERNAL_SYSCALL_ERRNO (r, err) == EINVAL)
  86           {
  87             /* The kernel doesn't support these clocks at all.  */
  88             __libc_missing_posix_cpu_timers = 1;
  89           }
  90       else
  91         return INTERNAL_SYSCALL_ERRNO (r, err);
  92     }
  93 # endif
  94 #endif
  95
  96 #ifdef CLOCK_THREAD_CPUTIME_ID
  97   /* We need to store the thread ID in the CLOCKID variable together
  98      with a number identifying the clock.  We reserve the low 3 bits
  99      for the clock ID and the rest for the thread ID.  This is
 100      problematic if the thread ID is too large.  But 29 bits should be
 101      fine.
 102
 103      If some day more clock IDs are needed the ID part can be
 104      enlarged.  The IDs are entirely internal.  */
 105   if (2 * PTHREAD_THREADS_MAX
 106       >= 1 << (8 * sizeof (*clock_id) - CLOCK_IDFIELD_SIZE))
 107     return ERANGE;
 108
 109   /* Store the number.  */
 110   *clock_id = CLOCK_THREAD_CPUTIME_ID | (thread_id << CLOCK_IDFIELD_SIZE);
 111
 112   return 0;
 113 #else
 114   /* We don't have a timer for that.  */
 115   return ENOENT;
 116 #endif
 117 }