nptl/libc-cancellation.c

   1 /* Copyright (C) 2002 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3    Contributed by Ulrich Drepper <drepper@redhat.com>, 2002.
   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 <setjmp.h>
  21 #include <stdlib.h>
  22 #include "pthreadP.h"
  23 #include "atomic.h"
  24
  25
  26 #ifndef NOT_IN_libc
  27
  28 /* The next two functions are similar to pthread_setcanceltype() but
  29    more specialized for the use in the cancelable functions like write().
  30    They do not need to check parameters etc.  */
  31 int
  32 attribute_hidden
  33 __libc_enable_asynccancel (void)
  34 {
  35   struct pthread *self = THREAD_SELF;
  36   int oldval;
  37
  38   while (1)
  39     {
  40       oldval = THREAD_GETMEM (self, cancelhandling);
  41       int newval = oldval | CANCELTYPE_BITMASK;
  42
  43       if (newval == oldval)
  44         break;
  45
  46       if (atomic_compare_and_exchange_acq (&self->cancelhandling, newval,
  47                                            oldval) == 0)
  48         {
  49           if (CANCEL_ENABLED_AND_CANCELED_AND_ASYNCHRONOUS (newval))
  50             {
  51               THREAD_SETMEM (self, result, PTHREAD_CANCELED);
  52               __do_cancel ();
  53             }
  54
  55           break;
  56         }
  57     }
  58
  59   return oldval;
  60 }
  61
  62
  63 void
  64 internal_function attribute_hidden
  65 __libc_disable_asynccancel (int oldtype)
  66 {
  67   /* If asynchronous cancellation was enabled before we do not have
  68      anything to do.  */
  69   if (oldtype & CANCELTYPE_BITMASK)
  70     return;
  71
  72   struct pthread *self = THREAD_SELF;
  73
  74   while (1)
  75     {
  76       int oldval = THREAD_GETMEM (self, cancelhandling);
  77       int newval = oldval & ~CANCELTYPE_BITMASK;
  78
  79       if (newval == oldval)
  80         break;
  81
  82       if (atomic_compare_and_exchange_acq (&self->cancelhandling, newval,
  83                                            oldval) == 0)
  84         break;
  85     }
  86 }
  87
  88 #endif