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1/* Demo leapsecond deadlock2 * by: John Stultz (john.stultz@linaro.org)3 * (C) Copyright IBM 20124 * (C) Copyright 2013, 2015 Linaro Limited5 * Licensed under the GPL6 *7 * This test demonstrates leapsecond deadlock that is possible8 * on kernels from 2.6.26 to 3.3.9 *10 * WARNING: THIS WILL LIKELY HARD HANG SYSTEMS AND MAY LOSE DATA11 * RUN AT YOUR OWN RISK!12 * To build:13 * $ gcc leapcrash.c -o leapcrash -lrt14 */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#include "../kselftest.h"26 27/* clear NTP time_status & time_state */28int clear_time_state(void)29{30 struct timex tx;31 int ret;32 33 /*34 * We have to call adjtime twice here, as kernels35 * prior to 6b1859dba01c7 (included in 3.5 and36 * -stable), had an issue with the state machine37 * and wouldn't clear the STA_INS/DEL flag directly.38 */39 tx.modes = ADJ_STATUS;40 tx.status = STA_PLL;41 ret = adjtimex(&tx);42 43 tx.modes = ADJ_STATUS;44 tx.status = 0;45 ret = adjtimex(&tx);46 47 return ret;48}49 50/* Make sure we cleanup on ctrl-c */51void handler(int unused)52{53 clear_time_state();54 exit(0);55}56 57 58int main(void)59{60 struct timex tx;61 struct timespec ts;62 time_t next_leap;63 int count = 0;64 65 setbuf(stdout, NULL);66 67 signal(SIGINT, handler);68 signal(SIGKILL, handler);69 printf("This runs for a few minutes. Press ctrl-c to stop\n");70 71 clear_time_state();72 73 74 /* Get the current time */75 clock_gettime(CLOCK_REALTIME, &ts);76 77 /* Calculate the next possible leap second 23:59:60 GMT */78 next_leap = ts.tv_sec;79 next_leap += 86400 - (next_leap % 86400);80 81 for (count = 0; count < 20; count++) {82 struct timeval tv;83 84 85 /* set the time to 2 seconds before the leap */86 tv.tv_sec = next_leap - 2;87 tv.tv_usec = 0;88 if (settimeofday(&tv, NULL)) {89 printf("Error: You're likely not running with proper (ie: root) permissions\n");90 ksft_exit_fail();91 }92 tx.modes = 0;93 adjtimex(&tx);94 95 /* hammer on adjtime w/ STA_INS */96 while (tx.time.tv_sec < next_leap + 1) {97 /* Set the leap second insert flag */98 tx.modes = ADJ_STATUS;99 tx.status = STA_INS;100 adjtimex(&tx);101 }102 clear_time_state();103 printf(".");104 fflush(stdout);105 }106 printf("[OK]\n");107 ksft_exit_pass();108}109