1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Copyright (C) 2013 Red Hat, Inc., Frederic Weisbecker <fweisbec@redhat.com>
4 *
5 * Selftests for a few posix timers interface.
6 *
7 * Kernel loop code stolen from Steven Rostedt <srostedt@redhat.com>
8 */
9
10 #include <sys/time.h>
11 #include <stdio.h>
12 #include <signal.h>
13 #include <unistd.h>
14 #include <time.h>
15 #include <pthread.h>
16
17 #include "../kselftest.h"
18
19 #define DELAY 2
20 #define USECS_PER_SEC 1000000
21
22 static volatile int done;
23
24 /* Busy loop in userspace to elapse ITIMER_VIRTUAL */
25 static void user_loop(void)
26 {
27 while (!done);
28 }
29
30 /*
31 * Try to spend as much time as possible in kernelspace
32 * to elapse ITIMER_PROF.
33 */
34 static void kernel_loop(void)
35 {
36 void *addr = sbrk(0);
37 int err = 0;
38
39 while (!done && !err) {
40 err = brk(addr + 4096);
41 err |= brk(addr);
42 }
43 }
44
45 /*
46 * Sleep until ITIMER_REAL expiration.
47 */
48 static void idle_loop(void)
49 {
50 pause();
51 }
52
53 static void sig_handler(int nr)
54 {
55 done = 1;
56 }
57
58 /*
59 * Check the expected timer expiration matches the GTOD elapsed delta since
60 * we armed the timer. Keep a 0.5 sec error margin due to various jitter.
61 */
62 static int check_diff(struct timeval start, struct timeval end)
63 {
64 long long diff;
65
66 diff = end.tv_usec - start.tv_usec;
67 diff += (end.tv_sec - start.tv_sec) * USECS_PER_SEC;
68
69 if (llabs(diff - DELAY * USECS_PER_SEC) > USECS_PER_SEC / 2) {
70 printf("Diff too high: %lld..", diff);
71 return -1;
72 }
73
74 return 0;
75 }
76
77 static int check_itimer(int which)
78 {
79 const char *name;
80 int err;
81 struct timeval start, end;
82 struct itimerval val = {
83 .it_value.tv_sec = DELAY,
84 };
85
86 if (which == ITIMER_VIRTUAL)
87 name = "ITIMER_VIRTUAL";
88 else if (which == ITIMER_PROF)
89 name = "ITIMER_PROF";
90 else if (which == ITIMER_REAL)
91 name = "ITIMER_REAL";
92 else
93 return -1;
94
95 done = 0;
96
97 if (which == ITIMER_VIRTUAL)
98 signal(SIGVTALRM, sig_handler);
99 else if (which == ITIMER_PROF)
100 signal(SIGPROF, sig_handler);
101 else if (which == ITIMER_REAL)
102 signal(SIGALRM, sig_handler);
103
104 err = gettimeofday(&start, NULL);
105 if (err < 0) {
106 ksft_perror("Can't call gettimeofday()");
107 return -1;
108 }
109
110 err = setitimer(which, &val, NULL);
111 if (err < 0) {
112 ksft_perror("Can't set timer");
113 return -1;
114 }
115
116 if (which == ITIMER_VIRTUAL)
117 user_loop();
118 else if (which == ITIMER_PROF)
119 kernel_loop();
120 else if (which == ITIMER_REAL)
121 idle_loop();
122
123 err = gettimeofday(&end, NULL);
124 if (err < 0) {
125 ksft_perror("Can't call gettimeofday()");
126 return -1;
127 }
128
129 ksft_test_result(check_diff(start, end) == 0, "%s\n", name);
130
131 return 0;
132 }
133
134 static int check_timer_create(int which)
135 {
136 const char *type;
137 int err;
138 timer_t id;
139 struct timeval start, end;
140 struct itimerspec val = {
141 .it_value.tv_sec = DELAY,
142 };
143
144 if (which == CLOCK_THREAD_CPUTIME_ID) {
145 type = "thread";
146 } else if (which == CLOCK_PROCESS_CPUTIME_ID) {
147 type = "process";
148 } else {
149 ksft_print_msg("Unknown timer_create() type %d\n", which);
150 return -1;
151 }
152
153 done = 0;
154 err = timer_create(which, NULL, &id);
155 if (err < 0) {
156 ksft_perror("Can't create timer");
157 return -1;
158 }
159 signal(SIGALRM, sig_handler);
160
161 err = gettimeofday(&start, NULL);
162 if (err < 0) {
163 ksft_perror("Can't call gettimeofday()");
164 return -1;
165 }
166
167 err = timer_settime(id, 0, &val, NULL);
168 if (err < 0) {
169 ksft_perror("Can't set timer");
170 return -1;
171 }
172
173 user_loop();
174
175 err = gettimeofday(&end, NULL);
176 if (err < 0) {
177 ksft_perror("Can't call gettimeofday()");
178 return -1;
179 }
180
181 ksft_test_result(check_diff(start, end) == 0,
182 "timer_create() per %s\n", type);
183
184 return 0;
185 }
186
187 static pthread_t ctd_thread;
188 static volatile int ctd_count, ctd_failed;
189
190 static void ctd_sighandler(int sig)
191 {
192 if (pthread_self() != ctd_thread)
193 ctd_failed = 1;
194 ctd_count--;
195 }
196
197 static void *ctd_thread_func(void *arg)
198 {
199 struct itimerspec val = {
200 .it_value.tv_sec = 0,
201 .it_value.tv_nsec = 1000 * 1000,
202 .it_interval.tv_sec = 0,
203 .it_interval.tv_nsec = 1000 * 1000,
204 };
205 timer_t id;
206
207 /* 1/10 seconds to ensure the leader sleeps */
208 usleep(10000);
209
210 ctd_count = 100;
211 if (timer_create(CLOCK_PROCESS_CPUTIME_ID, NULL, &id))
212 return "Can't create timer\n";
213 if (timer_settime(id, 0, &val, NULL))
214 return "Can't set timer\n";
215
216 while (ctd_count > 0 && !ctd_failed)
217 ;
218
219 if (timer_delete(id))
220 return "Can't delete timer\n";
221
222 return NULL;
223 }
224
225 /*
226 * Test that only the running thread receives the timer signal.
227 */
228 static int check_timer_distribution(void)
229 {
230 const char *errmsg;
231
232 signal(SIGALRM, ctd_sighandler);
233
234 errmsg = "Can't create thread\n";
235 if (pthread_create(&ctd_thread, NULL, ctd_thread_func, NULL))
236 goto err;
237
238 errmsg = "Can't join thread\n";
239 if (pthread_join(ctd_thread, (void **)&errmsg) || errmsg)
240 goto err;
241
242 if (!ctd_failed)
243 ksft_test_result_pass("check signal distribution\n");
244 else if (ksft_min_kernel_version(6, 3))
245 ksft_test_result_fail("check signal distribution\n");
246 else
247 ksft_test_result_skip("check signal distribution (old kernel)\n");
248 return 0;
249 err:
250 ksft_print_msg("%s", errmsg);
251 return -1;
252 }
253
254 int main(int argc, char **argv)
255 {
256 ksft_print_header();
257 ksft_set_plan(6);
258
259 ksft_print_msg("Testing posix timers. False negative may happen on CPU execution \n");
260 ksft_print_msg("based timers if other threads run on the CPU...\n");
261
262 if (check_itimer(ITIMER_VIRTUAL) < 0)
263 ksft_exit_fail();
264
265 if (check_itimer(ITIMER_PROF) < 0)
266 ksft_exit_fail();
267
268 if (check_itimer(ITIMER_REAL) < 0)
269 ksft_exit_fail();
270
271 if (check_timer_create(CLOCK_THREAD_CPUTIME_ID) < 0)
272 ksft_exit_fail();
273
274 /*
275 * It's unfortunately hard to reliably test a timer expiration
276 * on parallel multithread cputime. We could arm it to expire
277 * on DELAY * nr_threads, with nr_threads busy looping, then wait
278 * the normal DELAY since the time is elapsing nr_threads faster.
279 * But for that we need to ensure we have real physical free CPUs
280 * to ensure true parallelism. So test only one thread until we
281 * find a better solution.
282 */
283 if (check_timer_create(CLOCK_PROCESS_CPUTIME_ID) < 0)
284 ksft_exit_fail();
285
286 if (check_timer_distribution() < 0)
287 ksft_exit_fail();
288
289 ksft_finished();
290 }
291
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