1 /* Test that pthread_cancel succeeds during thread exit.
2 Copyright (C) 2021-2022 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
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 /* This test tries to trigger an internal race condition in
20 pthread_cancel, where the cancellation signal is sent after the
21 thread has begun the cancellation process. This can result in a
22 spurious ESRCH error. For the original bug 12889, the window is
23 quite small, so the bug was not reproduced in every run. */
24
25 #include <stdbool.h>
26 #include <stddef.h>
27 #include <support/check.h>
28 #include <support/xthread.h>
29 #include <support/xunistd.h>
30 #include <sys/select.h>
31 #include <unistd.h>
32
33 /* Set to true by timeout_thread_function when the test should
34 terminate. */
35 static bool timeout;
36
37 static void *
timeout_thread_function(void * unused)38 timeout_thread_function (void *unused)
39 {
40 usleep (5 * 1000 * 1000);
41 __atomic_store_n (&timeout, true, __ATOMIC_RELAXED);
42 return NULL;
43 }
44
45 /* Used for blocking the select function below. */
46 static int pipe_fds[2];
47
48 static void *
canceled_thread_function(void * unused)49 canceled_thread_function (void *unused)
50 {
51 while (true)
52 {
53 fd_set rfs;
54 fd_set wfs;
55 fd_set efs;
56 FD_ZERO (&rfs);
57 FD_ZERO (&wfs);
58 FD_ZERO (&efs);
59 FD_SET (pipe_fds[0], &rfs);
60
61 /* If the cancellation request is recognized early, the thread
62 begins exiting while the cancellation signal arrives. */
63 select (FD_SETSIZE, &rfs, &wfs, &efs, NULL);
64 }
65 return NULL;
66 }
67
68 static int
do_test(void)69 do_test (void)
70 {
71 xpipe (pipe_fds);
72 pthread_t thr_timeout = xpthread_create (NULL, timeout_thread_function, NULL);
73
74 while (!__atomic_load_n (&timeout, __ATOMIC_RELAXED))
75 {
76 pthread_t thr = xpthread_create (NULL, canceled_thread_function, NULL);
77 xpthread_cancel (thr);
78 TEST_VERIFY (xpthread_join (thr) == PTHREAD_CANCELED);
79 }
80
81 xpthread_join (thr_timeout);
82 xclose (pipe_fds[0]);
83 xclose (pipe_fds[1]);
84 return 0;
85 }
86
87 #include <support/test-driver.c>
88