xf.li | bdd93d5 | 2023-05-12 07:10:14 -0700 | [diff] [blame^] | 1 | /* Copyright (C) 2002-2016 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 <setjmp.h> |
| 20 | #include <stdlib.h> |
| 21 | #include "pthreadP.h" |
| 22 | #include <futex-internal.h> |
| 23 | |
| 24 | |
| 25 | /* The next two functions are similar to pthread_setcanceltype() but |
| 26 | more specialized for the use in the cancelable functions like write(). |
| 27 | They do not need to check parameters etc. */ |
| 28 | int |
| 29 | attribute_hidden |
| 30 | __pthread_enable_asynccancel (void) |
| 31 | { |
| 32 | struct pthread *self = THREAD_SELF; |
| 33 | int oldval = THREAD_GETMEM (self, cancelhandling); |
| 34 | |
| 35 | while (1) |
| 36 | { |
| 37 | int newval = oldval | CANCELTYPE_BITMASK; |
| 38 | |
| 39 | if (newval == oldval) |
| 40 | break; |
| 41 | |
| 42 | int curval = THREAD_ATOMIC_CMPXCHG_VAL (self, cancelhandling, newval, |
| 43 | oldval); |
| 44 | if (__glibc_likely (curval == oldval)) |
| 45 | { |
| 46 | if (CANCEL_ENABLED_AND_CANCELED_AND_ASYNCHRONOUS (newval)) |
| 47 | { |
| 48 | THREAD_SETMEM (self, result, PTHREAD_CANCELED); |
| 49 | __do_cancel (); |
| 50 | } |
| 51 | |
| 52 | break; |
| 53 | } |
| 54 | |
| 55 | /* Prepare the next round. */ |
| 56 | oldval = curval; |
| 57 | } |
| 58 | |
| 59 | return oldval; |
| 60 | } |
| 61 | |
| 62 | |
| 63 | void |
| 64 | internal_function attribute_hidden |
| 65 | __pthread_disable_asynccancel (int oldtype) |
| 66 | { |
| 67 | /* If asynchronous cancellation was enabled before we do not have |
| 68 | anything to do. */ |
| 69 | if (oldtype & CANCELTYPE_BITMASK) |
| 70 | return; |
| 71 | |
| 72 | struct pthread *self = THREAD_SELF; |
| 73 | int newval; |
| 74 | |
| 75 | int oldval = THREAD_GETMEM (self, cancelhandling); |
| 76 | |
| 77 | while (1) |
| 78 | { |
| 79 | newval = oldval & ~CANCELTYPE_BITMASK; |
| 80 | |
| 81 | int curval = THREAD_ATOMIC_CMPXCHG_VAL (self, cancelhandling, newval, |
| 82 | oldval); |
| 83 | if (__glibc_likely (curval == oldval)) |
| 84 | break; |
| 85 | |
| 86 | /* Prepare the next round. */ |
| 87 | oldval = curval; |
| 88 | } |
| 89 | |
| 90 | /* We cannot return when we are being canceled. Upon return the |
| 91 | thread might be things which would have to be undone. The |
| 92 | following loop should loop until the cancellation signal is |
| 93 | delivered. */ |
| 94 | while (__builtin_expect ((newval & (CANCELING_BITMASK | CANCELED_BITMASK)) |
| 95 | == CANCELING_BITMASK, 0)) |
| 96 | { |
| 97 | futex_wait_simple ((unsigned int *) &self->cancelhandling, newval, |
| 98 | FUTEX_PRIVATE); |
| 99 | newval = THREAD_GETMEM (self, cancelhandling); |
| 100 | } |
| 101 | } |