1 /*
2 * Copyright (C) 2015 Cyril Hrubis <chrubis@suse.cz>
3 *
4 * Licensed under the GNU GPLv2 or later.
5 * This program is free software; you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License as published by
7 * the Free Software Foundation; either version 2 of the License, or
8 * (at your option) any later version.
9 *
10 * This program 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
13 * the GNU General Public License for more details.
14 *
15 * You should have received a copy of the GNU General Public License
16 * along with this program; if not, write to the Free Software
17 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
18 */
19 /*
20 * Block several threads on a private mutex, then wake them up.
21 */
22
23 #include <errno.h>
24 #include <pthread.h>
25
26 #include "test.h"
27 #include "safe_macros.h"
28 #include "futextest.h"
29 #include "futex_utils.h"
30
31 const char *TCID="futex_wake02";
32 const int TST_TOTAL=11;
33
34 static futex_t futex = FUTEX_INITIALIZER;
35
36 static volatile int threads_flags[55];
37
threads_awake(void)38 static int threads_awake(void)
39 {
40 int ret = 0;
41 unsigned int i;
42
43 for (i = 0; i < ARRAY_SIZE(threads_flags); i++) {
44 if (threads_flags[i])
45 ret++;
46 }
47
48 return ret;
49 }
50
clear_threads_awake(void)51 static void clear_threads_awake(void)
52 {
53 unsigned int i;
54
55 for (i = 0; i < ARRAY_SIZE(threads_flags); i++)
56 threads_flags[i] = 0;
57 }
58
threaded(void * arg)59 static void *threaded(void *arg)
60 {
61 long i = (long)arg;
62
63 futex_wait(&futex, futex, NULL, FUTEX_PRIVATE_FLAG);
64
65 threads_flags[i] = 1;
66
67 return NULL;
68 }
69
do_child(void)70 static void do_child(void)
71 {
72 int res, i, j, awake;
73 pthread_t t[55];
74
75 for (i = 0; i < (int)ARRAY_SIZE(t); i++) {
76 res = pthread_create(&t[i], NULL, threaded, (void*)((long)i));
77 if (res) {
78 tst_brkm(TBROK, NULL, "pthread_create(): %s",
79 tst_strerrno(res));
80 }
81 }
82
83 while (wait_for_threads(ARRAY_SIZE(t)))
84 usleep(100);
85
86 for (i = 1; i <= 10; i++) {
87 clear_threads_awake();
88 res = futex_wake(&futex, i, FUTEX_PRIVATE_FLAG);
89 if (i != res) {
90 tst_resm(TFAIL,
91 "futex_wake() woken up %i threads, expected %i",
92 res, i);
93 }
94
95 for (j = 0; j < 100000; j++) {
96 awake = threads_awake();
97 if (awake == i)
98 break;
99
100 usleep(100);
101 }
102
103 if (awake == i) {
104 tst_resm(TPASS, "futex_wake() woken up %i threads", i);
105 } else {
106 tst_resm(TFAIL, "Woken up %i threads, expected %i",
107 awake, i);
108 }
109 }
110
111 res = futex_wake(&futex, 1, FUTEX_PRIVATE_FLAG);
112
113 if (res) {
114 tst_resm(TFAIL, "futex_wake() woken up %i, none were waiting",
115 res);
116 } else {
117 tst_resm(TPASS, "futex_wake() woken up 0 threads");
118 }
119
120 for (i = 0; i < (int)ARRAY_SIZE(t); i++)
121 pthread_join(t[i], NULL);
122
123 tst_exit();
124 }
125
126 /*
127 * We do the real test in a child because with the test -i parameter the loop
128 * that checks that all threads are sleeping may fail with ENOENT. That is
129 * because some of the threads from previous run may still be there.
130 *
131 * Which is because the userspace part of pthread_join() sleeps in a futex on a
132 * pthread tid which is woken up at the end of the exit_mm(tsk) which is before
133 * the process is removed from the parent thread_group list. So there is a
134 * small race window where the readdir() returns the process tid as a directory
135 * under /proc/$PID/tasks/, but the subsequent open() fails with ENOENT because
136 * the thread was removed meanwhile.
137 */
verify_futex_wake(void)138 static void verify_futex_wake(void)
139 {
140 int pid;
141
142 pid = tst_fork();
143
144 switch (pid) {
145 case 0:
146 do_child();
147 case -1:
148 tst_brkm(TBROK | TERRNO, NULL, "fork() failed");
149 default:
150 tst_record_childstatus(NULL, pid);
151 }
152 }
153
main(int argc,char * argv[])154 int main(int argc, char *argv[])
155 {
156 int lc;
157
158 tst_parse_opts(argc, argv, NULL, NULL);
159
160 for (lc = 0; TEST_LOOPING(lc); lc++)
161 verify_futex_wake();
162
163 tst_exit();
164 }
165