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 | |
24 | int |
25 | __pthread_setcanceltype (int type, int *oldtype) |
26 | { |
27 | if (type < PTHREAD_CANCEL_DEFERRED || type > PTHREAD_CANCEL_ASYNCHRONOUS) |
28 | return EINVAL; |
29 | |
30 | volatile struct pthread *self = THREAD_SELF; |
31 | |
32 | int oldval = THREAD_GETMEM (self, cancelhandling); |
33 | while (1) |
34 | { |
35 | int newval = (type == PTHREAD_CANCEL_ASYNCHRONOUS |
36 | ? oldval | CANCELTYPE_BITMASK |
37 | : oldval & ~CANCELTYPE_BITMASK); |
38 | |
39 | /* Store the old value. */ |
40 | if (oldtype != NULL) |
41 | *oldtype = ((oldval & CANCELTYPE_BITMASK) |
42 | ? PTHREAD_CANCEL_ASYNCHRONOUS : PTHREAD_CANCEL_DEFERRED); |
43 | |
44 | /* Avoid doing unnecessary work. The atomic operation can |
45 | potentially be expensive if the memory has to be locked and |
46 | remote cache lines have to be invalidated. */ |
47 | if (oldval == newval) |
48 | break; |
49 | |
50 | /* Update the cancel handling word. This has to be done |
51 | atomically since other bits could be modified as well. */ |
52 | int curval = THREAD_ATOMIC_CMPXCHG_VAL (self, cancelhandling, newval, |
53 | oldval); |
54 | if (__glibc_likely (curval == oldval)) |
55 | { |
56 | if (CANCEL_ENABLED_AND_CANCELED_AND_ASYNCHRONOUS (newval)) |
57 | { |
58 | THREAD_SETMEM (self, result, PTHREAD_CANCELED); |
59 | __do_cancel (); |
60 | } |
61 | |
62 | break; |
63 | } |
64 | |
65 | /* Prepare for the next round. */ |
66 | oldval = curval; |
67 | } |
68 | |
69 | return 0; |
70 | } |
71 | strong_alias (__pthread_setcanceltype, pthread_setcanceltype) |
72 | |