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

   1 /* Copyright (C) 2003, 2004, 2006, 2007 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3    Contributed by Ulrich Drepper <drepper@redhat.com>, 2003.
   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
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the 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; if not, write to the Free
  17    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  18    02111-1307 USA.  */
  19
  20 #include <alloca.h>
  21 #include <errno.h>
  22 #include <pthreadP.h>
  23 #include <sysdep.h>
  24 #include <sys/types.h>
  25 #include <shlib-compat.h>
  26
  27
  28 size_t __kernel_cpumask_size attribute_hidden;
  29
  30
  31 /* Determine the current affinity.  As a side affect we learn
  32    about the size of the cpumask_t in the kernel.  */
  33 int
  34 __determine_cpumask_size (pid_t tid)
  35 {
  36   INTERNAL_SYSCALL_DECL (err);
  37   int res;
  38
  39   size_t psize = 128;
  40   void *p = alloca (psize);
  41
  42   while (res = INTERNAL_SYSCALL (sched_getaffinity, err, 3, tid, psize, p),
  43          INTERNAL_SYSCALL_ERROR_P (res, err)
  44          && INTERNAL_SYSCALL_ERRNO (res, err) == EINVAL)
  45     p = extend_alloca (p, psize, 2 * psize);
  46
  47   if (res == 0 || INTERNAL_SYSCALL_ERROR_P (res, err))
  48     return INTERNAL_SYSCALL_ERRNO (res, err);
  49
  50   __kernel_cpumask_size = res;
  51
  52   return 0;
  53 }
  54
  55
  56 int
  57 __pthread_setaffinity_new (pthread_t th, size_t cpusetsize,
  58                            const cpu_set_t *cpuset)
  59 {
  60   const struct pthread *pd = (const struct pthread *) th;
  61
  62   INTERNAL_SYSCALL_DECL (err);
  63   int res;
  64
  65   if (__builtin_expect (__kernel_cpumask_size == 0, 0))
  66     {
  67       res = __determine_cpumask_size (pd->tid);
  68       if (res != 0)
  69         return res;
  70     }
  71
  72   /* We now know the size of the kernel cpumask_t.  Make sure the user
  73      does not request to set a bit beyond that.  */
  74   for (size_t cnt = __kernel_cpumask_size; cnt < cpusetsize; ++cnt)
  75     if (((char *) cpuset)[cnt] != '\0')
  76       /* Found a nonzero byte.  This means the user request cannot be
  77          fulfilled.  */
  78       return EINVAL;
  79
  80   res = INTERNAL_SYSCALL (sched_setaffinity, err, 3, pd->tid, cpusetsize,
  81                           cpuset);
  82
  83 #ifdef RESET_VGETCPU_CACHE
  84   if (!INTERNAL_SYSCALL_ERROR_P (res, err))
  85     RESET_VGETCPU_CACHE ();
  86 #endif
  87
  88   return (INTERNAL_SYSCALL_ERROR_P (res, err)
  89           ? INTERNAL_SYSCALL_ERRNO (res, err)
  90           : 0);
  91 }
  92 versioned_symbol (libpthread, __pthread_setaffinity_new,
  93                   pthread_setaffinity_np, GLIBC_2_3_4);
  94
  95
  96 #if SHLIB_COMPAT (libpthread, GLIBC_2_3_3, GLIBC_2_3_4)
  97 int
  98 __pthread_setaffinity_old (pthread_t th, cpu_set_t *cpuset)
  99 {
 100   /* The old interface by default assumed a 1024 processor bitmap.  */
 101   return __pthread_setaffinity_new (th, 128, cpuset);
 102 }
 103 compat_symbol (libpthread, __pthread_setaffinity_old, pthread_setaffinity_np,
 104                GLIBC_2_3_3);
 105 #endif