LXR linux/tools/testing/selftests/timers/leapcrash.c

   1/* Demo leapsecond deadlock
   2 *              by: John Stultz (john.stultz@linaro.org)
   3 *              (C) Copyright IBM 2012
   4 *              (C) Copyright 2013, 2015 Linaro Limited
   5 *              Licensed under the GPL
   6 *
   7 * This test demonstrates leapsecond deadlock that is possibe
   8 * on kernels from 2.6.26 to 3.3.
   9 *
  10 * WARNING: THIS WILL LIKELY HARDHANG SYSTEMS AND MAY LOSE DATA
  11 * RUN AT YOUR OWN RISK!
  12 *  To build:
  13 *      $ gcc leapcrash.c -o leapcrash -lrt
  14 */
  15
  16
  17
  18#include <stdio.h>
  19#include <stdlib.h>
  20#include <time.h>
  21#include <sys/time.h>
  22#include <sys/timex.h>
  23#include <string.h>
  24#include <signal.h>
  25#ifdef KTEST
  26#include "../kselftest.h"
  27#else
  28static inline int ksft_exit_pass(void)
  29{
  30        exit(0);
  31}
  32static inline int ksft_exit_fail(void)
  33{
  34        exit(1);
  35}
  36#endif
  37
  38
  39
  40/* clear NTP time_status & time_state */
  41int clear_time_state(void)
  42{
  43        struct timex tx;
  44        int ret;
  45
  46        /*
  47         * We have to call adjtime twice here, as kernels
  48         * prior to 6b1859dba01c7 (included in 3.5 and
  49         * -stable), had an issue with the state machine
  50         * and wouldn't clear the STA_INS/DEL flag directly.
  51         */
  52        tx.modes = ADJ_STATUS;
  53        tx.status = STA_PLL;
  54        ret = adjtimex(&tx);
  55
  56        tx.modes = ADJ_STATUS;
  57        tx.status = 0;
  58        ret = adjtimex(&tx);
  59
  60        return ret;
  61}
  62
  63/* Make sure we cleanup on ctrl-c */
  64void handler(int unused)
  65{
  66        clear_time_state();
  67        exit(0);
  68}
  69
  70
  71int main(void)
  72{
  73        struct timex tx;
  74        struct timespec ts;
  75        time_t next_leap;
  76        int count = 0;
  77
  78        setbuf(stdout, NULL);
  79
  80        signal(SIGINT, handler);
  81        signal(SIGKILL, handler);
  82        printf("This runs for a few minutes. Press ctrl-c to stop\n");
  83
  84        clear_time_state();
  85
  86
  87        /* Get the current time */
  88        clock_gettime(CLOCK_REALTIME, &ts);
  89
  90        /* Calculate the next possible leap second 23:59:60 GMT */
  91        next_leap = ts.tv_sec;
  92        next_leap += 86400 - (next_leap % 86400);
  93
  94        for (count = 0; count < 20; count++) {
  95                struct timeval tv;
  96
  97
  98                /* set the time to 2 seconds before the leap */
  99                tv.tv_sec = next_leap - 2;
 100                tv.tv_usec = 0;
 101                if (settimeofday(&tv, NULL)) {
 102                        printf("Error: You're likely not running with proper (ie: root) permissions\n");
 103                        return ksft_exit_fail();
 104                }
 105                tx.modes = 0;
 106                adjtimex(&tx);
 107
 108                /* hammer on adjtime w/ STA_INS */
 109                while (tx.time.tv_sec < next_leap + 1) {
 110                        /* Set the leap second insert flag */
 111                        tx.modes = ADJ_STATUS;
 112                        tx.status = STA_INS;
 113                        adjtimex(&tx);
 114                }
 115                clear_time_state();
 116                printf(".");
 117        }
 118        printf("[OK]\n");
 119        return ksft_exit_pass();
 120}
 121