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1 | /* Copyright (C) 2002-2017 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 | __pthread_setcanceltype (int type, int *oldtype) | |
26 | { | |
27 | if (type < PTHREAD_CANCEL_DEFERRED || type > PTHREAD_CANCEL_ASYNCHRONOUS) | |
28 | return EINVAL; | |
29 | ||
30 | #ifndef SIGCANCEL | |
31 | if (type == PTHREAD_CANCEL_ASYNCHRONOUS) | |
32 | return ENOTSUP; | |
33 | #endif | |
34 | ||
35 | volatile struct pthread *self = THREAD_SELF; | |
36 | ||
37 | int oldval = THREAD_GETMEM (self, cancelhandling); | |
38 | while (1) | |
39 | { | |
40 | int newval = (type == PTHREAD_CANCEL_ASYNCHRONOUS | |
41 | ? oldval | CANCELTYPE_BITMASK | |
42 | : oldval & ~CANCELTYPE_BITMASK); | |
43 | ||
44 | /* Store the old value. */ | |
45 | if (oldtype != NULL) | |
46 | *oldtype = ((oldval & CANCELTYPE_BITMASK) | |
47 | ? PTHREAD_CANCEL_ASYNCHRONOUS : PTHREAD_CANCEL_DEFERRED); | |
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 (__glibc_likely (curval == oldval)) | |
60 | { | |
61 | if (CANCEL_ENABLED_AND_CANCELED_AND_ASYNCHRONOUS (newval)) | |
62 | { | |
63 | THREAD_SETMEM (self, result, PTHREAD_CANCELED); | |
64 | __do_cancel (); | |
65 | } | |
66 | ||
67 | break; | |
68 | } | |
69 | ||
70 | /* Prepare for the next round. */ | |
71 | oldval = curval; | |
72 | } | |
73 | ||
74 | return 0; | |
75 | } | |
76 | strong_alias (__pthread_setcanceltype, pthread_setcanceltype) |