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, see
17 <http://www.gnu.org/licenses/>. */
18
19 #include <errno.h>
20 #include "pthreadP.h"
21 #include <atomic.h>
22
23
24 int
25 attribute_protected
__pthread_setcancelstate(int state,int * oldstate)26 __pthread_setcancelstate (
27 int state,
28 int *oldstate)
29 {
30 volatile struct pthread *self;
31
32 if (state < PTHREAD_CANCEL_ENABLE || state > PTHREAD_CANCEL_DISABLE)
33 return EINVAL;
34
35 self = THREAD_SELF;
36
37 int oldval = THREAD_GETMEM (self, cancelhandling);
38 while (1)
39 {
40 int newval = (state == PTHREAD_CANCEL_DISABLE
41 ? oldval | CANCELSTATE_BITMASK
42 : oldval & ~CANCELSTATE_BITMASK);
43
44 /* Store the old value. */
45 if (oldstate != NULL)
46 *oldstate = ((oldval & CANCELSTATE_BITMASK)
47 ? PTHREAD_CANCEL_DISABLE : PTHREAD_CANCEL_ENABLE);
48
49 /* Avoid doing unnecessary work. The atomic operation can
50 potentially be expensive if the memory has to be locked and
51 remote cache lines have to be invalidated. */
52 if (oldval == newval)
53 break;
54
55 /* Update the cancel handling word. This has to be done
56 atomically since other bits could be modified as well. */
57 int curval = THREAD_ATOMIC_CMPXCHG_VAL (self, cancelhandling, newval,
58 oldval);
59 if (__builtin_expect (curval == oldval, 1))
60 {
61 if (CANCEL_ENABLED_AND_CANCELED_AND_ASYNCHRONOUS (newval))
62 __do_cancel ();
63
64 break;
65 }
66
67 /* Prepare for the next round. */
68 oldval = curval;
69 }
70
71 return 0;
72 }
73 strong_alias (__pthread_setcancelstate, pthread_setcancelstate)
74