sysdeps/unix/sysv/linux/pthread_setaffinity.c

   1 /* Copyright (C) 2003-2015 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, see
  17    <http://www.gnu.org/licenses/>.  */
  18
  19 #include <alloca.h>
  20 #include <errno.h>
  21 #include <pthreadP.h>
  22 #include <sysdep.h>
  23 #include <sys/types.h>
  24 #include <shlib-compat.h>
  25
  26
  27 size_t __kernel_cpumask_size attribute_hidden;
  28
  29
  30 /* Determine the current affinity.  As a side affect we learn
  31    about the size of the cpumask_t in the kernel.  */
  32 int
  33 __determine_cpumask_size (pid_t tid)
  34 {
  35   INTERNAL_SYSCALL_DECL (err);
  36   int res;
  37
  38   size_t psize = 128;
  39   void *p = alloca (psize);
  40
  41   while (res = INTERNAL_SYSCALL (sched_getaffinity, err, 3, tid, psize, p),
  42          INTERNAL_SYSCALL_ERROR_P (res, err)
  43          && INTERNAL_SYSCALL_ERRNO (res, err) == EINVAL)
  44     p = extend_alloca (p, psize, 2 * psize);
  45
  46   if (res == 0 || INTERNAL_SYSCALL_ERROR_P (res, err))
  47     return INTERNAL_SYSCALL_ERRNO (res, err);
  48
  49   __kernel_cpumask_size = res;
  50
  51   return 0;
  52 }
  53
  54
  55 int
  56 __pthread_setaffinity_new (pthread_t th, size_t cpusetsize,
  57                            const cpu_set_t *cpuset)
  58 {
  59   const struct pthread *pd = (const struct pthread *) th;
  60
  61   INTERNAL_SYSCALL_DECL (err);
  62   int res;
  63
  64   if (__glibc_unlikely (__kernel_cpumask_size == 0))
  65     {
  66       res = __determine_cpumask_size (pd->tid);
  67       if (res != 0)
  68         return res;
  69     }
  70
  71   /* We now know the size of the kernel cpumask_t.  Make sure the user
  72      does not request to set a bit beyond that.  */
  73   for (size_t cnt = __kernel_cpumask_size; cnt < cpusetsize; ++cnt)
  74     if (((char *) cpuset)[cnt] != '\0')
  75       /* Found a nonzero byte.  This means the user request cannot be
  76          fulfilled.  */
  77       return EINVAL;
  78
  79   res = INTERNAL_SYSCALL (sched_setaffinity, err, 3, pd->tid, cpusetsize,
  80                           cpuset);
  81
  82 #ifdef RESET_VGETCPU_CACHE
  83   if (!INTERNAL_SYSCALL_ERROR_P (res, err))
  84     RESET_VGETCPU_CACHE ();
  85 #endif
  86
  87   return (INTERNAL_SYSCALL_ERROR_P (res, err)
  88           ? INTERNAL_SYSCALL_ERRNO (res, err)
  89           : 0);
  90 }
  91 versioned_symbol (libpthread, __pthread_setaffinity_new,
  92                   pthread_setaffinity_np, GLIBC_2_3_4);
  93
  94
  95 #if SHLIB_COMPAT (libpthread, GLIBC_2_3_3, GLIBC_2_3_4)
  96 int
  97 __pthread_setaffinity_old (pthread_t th, cpu_set_t *cpuset)
  98 {
  99   /* The old interface by default assumed a 1024 processor bitmap.  */
 100   return __pthread_setaffinity_new (th, 128, cpuset);
 101 }
 102 compat_symbol (libpthread, __pthread_setaffinity_old, pthread_setaffinity_np,
 103                GLIBC_2_3_3);
 104 #endif