1/* Copyright (C) 2002-2023 Free Software Foundation, Inc.
2 This file is part of the GNU C Library.
3
4 The GNU C Library is free software; you can redistribute it and/or
5 modify it under the terms of the GNU Lesser General Public
6 License as published by the Free Software Foundation; either
7 version 2.1 of the License, or (at your option) any later version.
8
9 The GNU C Library is distributed in the hope that it will be useful,
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 Lesser General Public License for more details.
13
14 You should have received a copy of the GNU Lesser General Public
15 License along with the GNU C Library; if not, see
16 <https://www.gnu.org/licenses/>. */
17
18#include <setjmp.h>
19#include <stdlib.h>
20#include "pthreadP.h"
21#include <futex-internal.h>
22
23
24/* The next two functions are similar to pthread_setcanceltype() but
25 more specialized for the use in the cancelable functions like write().
26 They do not need to check parameters etc. These functions must be
27 AS-safe, with the exception of the actual cancellation, because they
28 are called by wrappers around AS-safe functions like write().*/
29int
30__pthread_enable_asynccancel (void)
31{
32 struct pthread *self = THREAD_SELF;
33 int oldval = atomic_load_relaxed (&self->cancelhandling);
34
35 while (1)
36 {
37 int newval = oldval | CANCELTYPE_BITMASK;
38
39 if (newval == oldval)
40 break;
41
42 if (atomic_compare_exchange_weak_acquire (&self->cancelhandling,
43 &oldval, newval))
44 {
45 if (cancel_enabled_and_canceled_and_async (newval))
46 {
47 self->result = PTHREAD_CANCELED;
48 __do_cancel ();
49 }
50
51 break;
52 }
53 }
54
55 return oldval;
56}
57libc_hidden_def (__pthread_enable_asynccancel)
58
59/* See the comment for __pthread_enable_asynccancel regarding
60 the AS-safety of this function. */
61void
62__pthread_disable_asynccancel (int oldtype)
63{
64 /* If asynchronous cancellation was enabled before we do not have
65 anything to do. */
66 if (oldtype & CANCELTYPE_BITMASK)
67 return;
68
69 struct pthread *self = THREAD_SELF;
70 int newval;
71 int oldval = atomic_load_relaxed (&self->cancelhandling);
72 do
73 {
74 newval = oldval & ~CANCELTYPE_BITMASK;
75 }
76 while (!atomic_compare_exchange_weak_acquire (&self->cancelhandling,
77 &oldval, newval));
78
79 /* We cannot return when we are being canceled. Upon return the
80 thread might be things which would have to be undone. The
81 following loop should loop until the cancellation signal is
82 delivered. */
83 while (__glibc_unlikely ((newval & (CANCELING_BITMASK | CANCELED_BITMASK))
84 == CANCELING_BITMASK))
85 {
86 futex_wait_simple ((unsigned int *) &self->cancelhandling, newval,
87 FUTEX_PRIVATE);
88 newval = atomic_load_relaxed (&self->cancelhandling);
89 }
90}
91libc_hidden_def (__pthread_disable_asynccancel)
92