root/tools/testing/selftests/timers/clocksource-switch.c

DEFINITIONS

1. get_clocksources
2. get_cur_clocksource
3. change_clocksource
4. run_tests
5. main

   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 clocksourc 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 <stdio.h>
  27 #include <unistd.h>
  28 #include <stdlib.h>
  29 #include <sys/time.h>
  30 #include <sys/timex.h>
  31 #include <time.h>
  32 #include <sys/types.h>
  33 #include <sys/stat.h>
  34 #include <fcntl.h>
  35 #include <string.h>
  36 #include <sys/wait.h>
  37 #include "../kselftest.h"
  38 
  39 
  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 
  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 
  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 
 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 (ret)
 114                 return ret;
 115         ret = system("./nanosleep");
 116         return ret;
 117 }
 118 
 119 
 120 char clocksource_list[10][30];
 121 
 122 int main(int argv, char **argc)
 123 {
 124         char orig_clk[512];
 125         int count, i, status;
 126         pid_t pid;
 127 
 128         get_cur_clocksource(orig_clk, 512);
 129 
 130         count = get_clocksources(clocksource_list);
 131 
 132         if (change_clocksource(clocksource_list[0])) {
 133                 printf("Error: You probably need to run this as root\n");
 134                 return -1;
 135         }
 136 
 137         /* Check everything is sane before we start switching asyncrhonously */
 138         for (i = 0; i < count; i++) {
 139                 printf("Validating clocksource %s\n", clocksource_list[i]);
 140                 if (change_clocksource(clocksource_list[i])) {
 141                         status = -1;
 142                         goto out;
 143                 }
 144                 if (run_tests(5)) {
 145                         status = -1;
 146                         goto out;
 147                 }
 148         }
 149 
 150 
 151         printf("Running Asynchronous Switching Tests...\n");
 152         pid = fork();
 153         if (!pid)
 154                 return run_tests(60);
 155 
 156         while (pid != waitpid(pid, &status, WNOHANG))
 157                 for (i = 0; i < count; i++)
 158                         if (change_clocksource(clocksource_list[i])) {
 159                                 status = -1;
 160                                 goto out;
 161                         }
 162 out:
 163         change_clocksource(orig_clk);
 164 
 165         if (status)
 166                 return ksft_exit_fail();
 167         return ksft_exit_pass();
 168 }