1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /******************************************************************************
3 *
4 * Copyright © International Business Machines Corp., 2009
5 *
6 * DESCRIPTION
7 * Block on a futex and wait for timeout.
8 *
9 * AUTHOR
10 * Darren Hart <dvhart@linux.intel.com>
11 *
12 * HISTORY
13 * 2009-Nov-6: Initial version by Darren Hart <dvhart@linux.intel.com>
14 * 2021-Apr-26: More test cases by André Almeida <andrealmeid@collabora.com>
15 *
16 *****************************************************************************/
17
18 #include <pthread.h>
19 #include "futextest.h"
20 #include "logging.h"
21
22 #define TEST_NAME "futex-wait-timeout"
23
24 static long timeout_ns = 100000; /* 100us default timeout */
25 static futex_t futex_pi;
26 static pthread_barrier_t barrier;
27
usage(char * prog)28 void usage(char *prog)
29 {
30 printf("Usage: %s\n", prog);
31 printf(" -c Use color\n");
32 printf(" -h Display this help message\n");
33 printf(" -t N Timeout in nanoseconds (default: 100,000)\n");
34 printf(" -v L Verbosity level: %d=QUIET %d=CRITICAL %d=INFO\n",
35 VQUIET, VCRITICAL, VINFO);
36 }
37
38 /*
39 * Get a PI lock and hold it forever, so the main thread lock_pi will block
40 * and we can test the timeout
41 */
get_pi_lock(void * arg)42 void *get_pi_lock(void *arg)
43 {
44 int ret;
45 volatile futex_t lock = 0;
46
47 ret = futex_lock_pi(&futex_pi, NULL, 0, 0);
48 if (ret != 0)
49 error("futex_lock_pi failed\n", ret);
50
51 pthread_barrier_wait(&barrier);
52
53 /* Blocks forever */
54 ret = futex_wait(&lock, 0, NULL, 0);
55 error("futex_wait failed\n", ret);
56
57 return NULL;
58 }
59
60 /*
61 * Check if the function returned the expected error
62 */
test_timeout(int res,int * ret,char * test_name,int err)63 static void test_timeout(int res, int *ret, char *test_name, int err)
64 {
65 if (!res || errno != err) {
66 ksft_test_result_fail("%s returned %d\n", test_name,
67 res < 0 ? errno : res);
68 *ret = RET_FAIL;
69 } else {
70 ksft_test_result_pass("%s succeeds\n", test_name);
71 }
72 }
73
74 /*
75 * Calculate absolute timeout and correct overflow
76 */
futex_get_abs_timeout(clockid_t clockid,struct timespec * to,long timeout_ns)77 static int futex_get_abs_timeout(clockid_t clockid, struct timespec *to,
78 long timeout_ns)
79 {
80 if (clock_gettime(clockid, to)) {
81 error("clock_gettime failed\n", errno);
82 return errno;
83 }
84
85 to->tv_nsec += timeout_ns;
86
87 if (to->tv_nsec >= 1000000000) {
88 to->tv_sec++;
89 to->tv_nsec -= 1000000000;
90 }
91
92 return 0;
93 }
94
main(int argc,char * argv[])95 int main(int argc, char *argv[])
96 {
97 futex_t f1 = FUTEX_INITIALIZER;
98 int res, ret = RET_PASS;
99 struct timespec to;
100 pthread_t thread;
101 int c;
102
103 while ((c = getopt(argc, argv, "cht:v:")) != -1) {
104 switch (c) {
105 case 'c':
106 log_color(1);
107 break;
108 case 'h':
109 usage(basename(argv[0]));
110 exit(0);
111 case 't':
112 timeout_ns = atoi(optarg);
113 break;
114 case 'v':
115 log_verbosity(atoi(optarg));
116 break;
117 default:
118 usage(basename(argv[0]));
119 exit(1);
120 }
121 }
122
123 ksft_print_header();
124 ksft_set_plan(7);
125 ksft_print_msg("%s: Block on a futex and wait for timeout\n",
126 basename(argv[0]));
127 ksft_print_msg("\tArguments: timeout=%ldns\n", timeout_ns);
128
129 pthread_barrier_init(&barrier, NULL, 2);
130 pthread_create(&thread, NULL, get_pi_lock, NULL);
131
132 /* initialize relative timeout */
133 to.tv_sec = 0;
134 to.tv_nsec = timeout_ns;
135
136 res = futex_wait(&f1, f1, &to, 0);
137 test_timeout(res, &ret, "futex_wait relative", ETIMEDOUT);
138
139 /* FUTEX_WAIT_BITSET with CLOCK_REALTIME */
140 if (futex_get_abs_timeout(CLOCK_REALTIME, &to, timeout_ns))
141 return RET_FAIL;
142 res = futex_wait_bitset(&f1, f1, &to, 1, FUTEX_CLOCK_REALTIME);
143 test_timeout(res, &ret, "futex_wait_bitset realtime", ETIMEDOUT);
144
145 /* FUTEX_WAIT_BITSET with CLOCK_MONOTONIC */
146 if (futex_get_abs_timeout(CLOCK_MONOTONIC, &to, timeout_ns))
147 return RET_FAIL;
148 res = futex_wait_bitset(&f1, f1, &to, 1, 0);
149 test_timeout(res, &ret, "futex_wait_bitset monotonic", ETIMEDOUT);
150
151 /* FUTEX_WAIT_REQUEUE_PI with CLOCK_REALTIME */
152 if (futex_get_abs_timeout(CLOCK_REALTIME, &to, timeout_ns))
153 return RET_FAIL;
154 res = futex_wait_requeue_pi(&f1, f1, &futex_pi, &to, FUTEX_CLOCK_REALTIME);
155 test_timeout(res, &ret, "futex_wait_requeue_pi realtime", ETIMEDOUT);
156
157 /* FUTEX_WAIT_REQUEUE_PI with CLOCK_MONOTONIC */
158 if (futex_get_abs_timeout(CLOCK_MONOTONIC, &to, timeout_ns))
159 return RET_FAIL;
160 res = futex_wait_requeue_pi(&f1, f1, &futex_pi, &to, 0);
161 test_timeout(res, &ret, "futex_wait_requeue_pi monotonic", ETIMEDOUT);
162
163 /* Wait until the other thread calls futex_lock_pi() */
164 pthread_barrier_wait(&barrier);
165 pthread_barrier_destroy(&barrier);
166 /*
167 * FUTEX_LOCK_PI with CLOCK_REALTIME
168 * Due to historical reasons, FUTEX_LOCK_PI supports only realtime
169 * clock, but requires the caller to not set CLOCK_REALTIME flag.
170 *
171 * If you call FUTEX_LOCK_PI with a monotonic clock, it'll be
172 * interpreted as a realtime clock, and (unless you mess your machine's
173 * time or your time machine) the monotonic clock value is always
174 * smaller than realtime and the syscall will timeout immediately.
175 */
176 if (futex_get_abs_timeout(CLOCK_REALTIME, &to, timeout_ns))
177 return RET_FAIL;
178 res = futex_lock_pi(&futex_pi, &to, 0, 0);
179 test_timeout(res, &ret, "futex_lock_pi realtime", ETIMEDOUT);
180
181 /* Test operations that don't support FUTEX_CLOCK_REALTIME */
182 res = futex_lock_pi(&futex_pi, NULL, 0, FUTEX_CLOCK_REALTIME);
183 test_timeout(res, &ret, "futex_lock_pi invalid timeout flag", ENOSYS);
184
185 ksft_print_cnts();
186 return ret;
187 }
188