1 /* Clocksource change test
2  *		by: john stultz (johnstul@us.ibm.com)
3  *		(C) Copyright IBM 2012
4  *		Licensed under the GPLv2
5  *
6  *  NOTE: This is a meta-test which quickly changes the clocksource and
7  *  then uses other tests to detect problems. Thus this test requires
8  *  that the inconsistency-check and nanosleep tests be present in the
9  *  same directory it is run from.
10  *
11  *  To build:
12  *	$ gcc clocksource-switch.c -o clocksource-switch -lrt
13  *
14  *   This program is free software: you can redistribute it and/or modify
15  *   it under the terms of the GNU General Public License as published by
16  *   the Free Software Foundation, either version 2 of the License, or
17  *   (at your option) any later version.
18  *
19  *   This program is distributed in the hope that it will be useful,
20  *   but WITHOUT ANY WARRANTY; without even the implied warranty of
21  *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
22  *   GNU General Public License for more details.
23  */
24 
25 
26 #include <fcntl.h>
27 #include <stdio.h>
28 #include <stdlib.h>
29 #include <string.h>
30 #include <sys/stat.h>
31 #include <sys/time.h>
32 #include <sys/timex.h>
33 #include <sys/types.h>
34 #include <sys/wait.h>
35 #include <time.h>
36 #include <unistd.h>
37 #include "../kselftest.h"
38 
39 
get_clocksources(char list[][30])40 int get_clocksources(char list[][30])
41 {
42 	int fd, i;
43 	size_t size;
44 	char buf[512];
45 	char *head, *tmp;
46 
47 	fd = open("/sys/devices/system/clocksource/clocksource0/available_clocksource", O_RDONLY);
48 
49 	size = read(fd, buf, 512);
50 
51 	close(fd);
52 
53 	for (i = 0; i < 10; i++)
54 		list[i][0] = '\0';
55 
56 	head = buf;
57 	i = 0;
58 	while (head - buf < size) {
59 		/* Find the next space */
60 		for (tmp = head; *tmp != ' '; tmp++) {
61 			if (*tmp == '\n')
62 				break;
63 			if (*tmp == '\0')
64 				break;
65 		}
66 		*tmp = '\0';
67 		strcpy(list[i], head);
68 		head = tmp + 1;
69 		i++;
70 	}
71 
72 	return i-1;
73 }
74 
get_cur_clocksource(char * buf,size_t size)75 int get_cur_clocksource(char *buf, size_t size)
76 {
77 	int fd;
78 
79 	fd = open("/sys/devices/system/clocksource/clocksource0/current_clocksource", O_RDONLY);
80 
81 	size = read(fd, buf, size);
82 
83 	return 0;
84 }
85 
change_clocksource(char * clocksource)86 int change_clocksource(char *clocksource)
87 {
88 	int fd;
89 	ssize_t size;
90 
91 	fd = open("/sys/devices/system/clocksource/clocksource0/current_clocksource", O_WRONLY);
92 
93 	if (fd < 0)
94 		return -1;
95 
96 	size = write(fd, clocksource, strlen(clocksource));
97 
98 	if (size < 0)
99 		return -1;
100 
101 	close(fd);
102 	return 0;
103 }
104 
105 
run_tests(int secs)106 int run_tests(int secs)
107 {
108 	int ret;
109 	char buf[255];
110 
111 	sprintf(buf, "./inconsistency-check -t %i", secs);
112 	ret = system(buf);
113 	if (WIFEXITED(ret) && WEXITSTATUS(ret))
114 		return WEXITSTATUS(ret);
115 	ret = system("./nanosleep");
116 	return WIFEXITED(ret) ? WEXITSTATUS(ret) : 0;
117 }
118 
119 
120 char clocksource_list[10][30];
121 
main(int argc,char ** argv)122 int main(int argc, char **argv)
123 {
124 	char orig_clk[512];
125 	int count, i, status, opt;
126 	int do_sanity_check = 1;
127 	int runtime = 60;
128 	pid_t pid;
129 
130 	/* Process arguments */
131 	while ((opt = getopt(argc, argv, "st:")) != -1) {
132 		switch (opt) {
133 		case 's':
134 			do_sanity_check = 0;
135 			break;
136 		case 't':
137 			runtime = atoi(optarg);
138 			break;
139 		default:
140 			printf("Usage: %s [-s] [-t <secs>]\n", argv[0]);
141 			printf("	-s: skip sanity checks\n");
142 			printf("	-t: Number of seconds to run\n");
143 			exit(-1);
144 		}
145 	}
146 
147 	get_cur_clocksource(orig_clk, 512);
148 
149 	count = get_clocksources(clocksource_list);
150 
151 	if (change_clocksource(clocksource_list[0])) {
152 		printf("Error: You probably need to run this as root\n");
153 		return -1;
154 	}
155 
156 	/* Check everything is sane before we start switching asynchronously */
157 	if (do_sanity_check) {
158 		for (i = 0; i < count; i++) {
159 			printf("Validating clocksource %s\n",
160 				clocksource_list[i]);
161 			if (change_clocksource(clocksource_list[i])) {
162 				status = -1;
163 				goto out;
164 			}
165 			if (run_tests(5)) {
166 				status = -1;
167 				goto out;
168 			}
169 		}
170 	}
171 
172 	printf("Running Asynchronous Switching Tests...\n");
173 	pid = fork();
174 	if (!pid)
175 		return run_tests(runtime);
176 
177 	while (pid != waitpid(pid, &status, WNOHANG))
178 		for (i = 0; i < count; i++)
179 			if (change_clocksource(clocksource_list[i])) {
180 				status = -1;
181 				goto out;
182 			}
183 out:
184 	change_clocksource(orig_clk);
185 
186 	/* Print at the end to not mix output with child process */
187 	ksft_print_header();
188 	ksft_set_plan(1);
189 	ksft_test_result(!status, "clocksource-switch\n");
190 	ksft_exit(!status);
191 }
192