nptl/libc-cancellation.c

   1 /* Copyright (C) 2002, 2003, 2005, 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 #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 or if PTHREAD_CANCEL_DISABLED,
  46              stop right here.  */
  47           if ((oldval & (EXITING_BITMASK | CANCELSTATE_BITMASK)) != 0)
  48             break;
  49
  50           int curval = THREAD_ATOMIC_CMPXCHG_VAL (self, cancelhandling,
  51                                                   newval, oldval);
  52           if (__builtin_expect (curval != oldval, 0))
  53             {
  54               /* Somebody else modified the word, try again.  */
  55               oldval = curval;
  56               continue;
  57             }
  58
  59           THREAD_SETMEM (self, result, PTHREAD_CANCELED);
  60
  61           __do_cancel ();
  62
  63           /* NOTREACHED */
  64         }
  65
  66       int curval = THREAD_ATOMIC_CMPXCHG_VAL (self, cancelhandling, newval,
  67                                               oldval);
  68       if (__builtin_expect (curval == oldval, 1))
  69         break;
  70
  71       /* Prepare the next round.  */
  72       oldval = curval;
  73     }
  74
  75   return oldval;
  76 }
  77
  78
  79 void
  80 internal_function attribute_hidden
  81 __libc_disable_asynccancel (int oldtype)
  82 {
  83   /* If asynchronous cancellation was enabled before we do not have
  84      anything to do.  */
  85   if (oldtype & CANCELTYPE_BITMASK)
  86     return;
  87
  88   struct pthread *self = THREAD_SELF;
  89
  90 #ifdef THREAD_ATOMIC_AND
  91   THREAD_ATOMIC_AND (self, cancelhandling, ~CANCELTYPE_BITMASK);
  92 #else
  93   int oldval = THREAD_GETMEM (self, cancelhandling);
  94
  95   while (1)
  96     {
  97       int newval = oldval & ~CANCELTYPE_BITMASK;
  98
  99       if (newval == oldval)
 100         break;
 101
 102       int curval = THREAD_ATOMIC_CMPXCHG_VAL (self, cancelhandling, newval,
 103                                               oldval);
 104       if (__builtin_expect (curval == oldval, 1))
 105         break;
 106
 107       /* Prepare the next round.  */
 108       oldval = curval;
 109     }
 110 #endif
 111 }
 112
 113
 114 void
 115 __libc_cleanup_routine (struct __pthread_cleanup_frame *f)
 116 {
 117   if (f->__do_it)
 118     f->__cancel_routine (f->__cancel_arg);
 119 }
 120
 121 #endif