nptl/libc-cancellation.c

   1 /* Copyright (C) 2002, 2003 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 #include <bits/libc-lock.h>
  25
  26
  27 #ifndef NOT_IN_libc
  28
  29 /* The next two functions are similar to pthread_setcanceltype() but
  30    more specialized for the use in the cancelable functions like write().
  31    They do not need to check parameters etc.  */
  32 int
  33 attribute_hidden
  34 __libc_enable_asynccancel (void)
  35 {
  36   struct pthread *self = THREAD_SELF;
  37   int oldval = THREAD_GETMEM (self, cancelhandling);
  38
  39   while (1)
  40     {
  41       int newval = oldval | CANCELTYPE_BITMASK;
  42
  43       if (__builtin_expect ((oldval & CANCELED_BITMASK) != 0, 0))
  44         {
  45           /* If we are already exiting stop right here.  */
  46           if ((oldval & EXITING_BITMASK) != 0)
  47             break;
  48
  49           int curval = THREAD_ATOMIC_CMPXCHG_VAL (self, cancelhandling,
  50                                                   newval, oldval);
  51           if (__builtin_expect (curval != oldval, 0))
  52             {
  53               /* Somebody else modified the word, try again.  */
  54               oldval = curval;
  55               continue;
  56             }
  57
  58           THREAD_SETMEM (self, result, PTHREAD_CANCELED);
  59
  60           __do_cancel ();
  61
  62           /* NOTREACHED */
  63         }
  64
  65       int curval = THREAD_ATOMIC_CMPXCHG_VAL (self, cancelhandling, newval,
  66                                               oldval);
  67       if (__builtin_expect (curval == oldval, 1))
  68         break;
  69
  70       /* Prepare the next round.  */
  71       oldval = curval;
  72     }
  73
  74   return oldval;
  75 }
  76
  77
  78 void
  79 internal_function attribute_hidden
  80 __libc_disable_asynccancel (int oldtype)
  81 {
  82   /* If asynchronous cancellation was enabled before we do not have
  83      anything to do.  */
  84   if (oldtype & CANCELTYPE_BITMASK)
  85     return;
  86
  87   struct pthread *self = THREAD_SELF;
  88   int oldval = THREAD_GETMEM (self, cancelhandling);
  89
  90   while (1)
  91     {
  92       int newval = oldval & ~CANCELTYPE_BITMASK;
  93
  94       if (newval == oldval)
  95         break;
  96
  97       int curval = THREAD_ATOMIC_CMPXCHG_VAL (self, cancelhandling, newval,
  98                                               oldval);
  99       if (__builtin_expect (curval == oldval, 1))
 100         break;
 101
 102       /* Prepare the next round.  */
 103       oldval = curval;
 104     }
 105 }
 106
 107
 108 void
 109 __libc_cleanup_routine (struct __pthread_cleanup_frame *f)
 110 {
 111   if (f->__do_it)
 112     f->__cancel_routine (f->__cancel_arg);
 113 }
 114
 115 #endif