nptl/cancellation.c

   1 /* Copyright (C) 2002, 2003, 2009 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
  24
  25 /* The next two functions are similar to pthread_setcanceltype() but
  26    more specialized for the use in the cancelable functions like write().
  27    They do not need to check parameters etc.  */
  28 int
  29 attribute_hidden
  30 __pthread_enable_asynccancel (void)
  31 {
  32   struct pthread *self = THREAD_SELF;
  33   int oldval = THREAD_GETMEM (self, cancelhandling);
  34
  35   while (1)
  36     {
  37       int newval = oldval | CANCELTYPE_BITMASK;
  38
  39       if (newval == oldval)
  40         break;
  41
  42       int curval = THREAD_ATOMIC_CMPXCHG_VAL (self, cancelhandling, newval,
  43                                               oldval);
  44       if (__builtin_expect (curval == oldval, 1))
  45         {
  46           if (CANCEL_ENABLED_AND_CANCELED_AND_ASYNCHRONOUS (newval))
  47             {
  48               THREAD_SETMEM (self, result, PTHREAD_CANCELED);
  49               __do_cancel ();
  50             }
  51
  52           break;
  53         }
  54
  55       /* Prepare the next round.  */
  56       oldval = curval;
  57     }
  58
  59   return oldval;
  60 }
  61
  62
  63 void
  64 internal_function attribute_hidden
  65 __pthread_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 #ifdef THREAD_ATOMIC_AND
  75   THREAD_ATOMIC_AND (self, cancelhandling, ~CANCELTYPE_BITMASK);
  76 #else
  77   int oldval = THREAD_GETMEM (self, cancelhandling);
  78
  79   while (1)
  80     {
  81       int newval = oldval & ~CANCELTYPE_BITMASK;
  82
  83       if (newval == oldval)
  84         break;
  85
  86       int curval = THREAD_ATOMIC_CMPXCHG_VAL (self, cancelhandling, newval,
  87                                               oldval);
  88       if (__builtin_expect (curval == oldval, 1))
  89         break;
  90
  91       /* Prepare the next round.  */
  92       oldval = curval;
  93     }
  94 #endif
  95 }