1/* Copyright (C) 2002-2020 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 <https://www.gnu.org/licenses/>. */
18
19#include <errno.h>
20#include "pthreadP.h"
21#include <atomic.h>
22
23
24int
25__pthread_setcancelstate (int state, int *oldstate)
26{
27 volatile struct pthread *self;
28
29 if (state < PTHREAD_CANCEL_ENABLE || state > PTHREAD_CANCEL_DISABLE)
30 return EINVAL;
31
32 self = THREAD_SELF;
33
34 int oldval = THREAD_GETMEM (self, cancelhandling);
35 while (1)
36 {
37 int newval = (state == PTHREAD_CANCEL_DISABLE
38 ? oldval | CANCELSTATE_BITMASK
39 : oldval & ~CANCELSTATE_BITMASK);
40
41 /* Store the old value. */
42 if (oldstate != NULL)
43 *oldstate = ((oldval & CANCELSTATE_BITMASK)
44 ? PTHREAD_CANCEL_DISABLE : PTHREAD_CANCEL_ENABLE);
45
46 /* Avoid doing unnecessary work. The atomic operation can
47 potentially be expensive if the memory has to be locked and
48 remote cache lines have to be invalidated. */
49 if (oldval == newval)
50 break;
51
52 /* Update the cancel handling word. This has to be done
53 atomically since other bits could be modified as well. */
54 int curval = THREAD_ATOMIC_CMPXCHG_VAL (self, cancelhandling, newval,
55 oldval);
56 if (__glibc_likely (curval == oldval))
57 {
58 if (CANCEL_ENABLED_AND_CANCELED_AND_ASYNCHRONOUS (newval))
59 __do_cancel ();
60
61 break;
62 }
63
64 /* Prepare for the next round. */
65 oldval = curval;
66 }
67
68 return 0;
69}
70strong_alias (__pthread_setcancelstate, pthread_setcancelstate)
71hidden_def (__pthread_setcancelstate)
72