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/* Demo leapsecond deadlock
* by: John Stultz (john.stultz@linaro.org)
* (C) Copyright IBM 2012
* (C) Copyright 2013, 2015 Linaro Limited
* Licensed under the GPL
*
* This test demonstrates leapsecond deadlock that is possibe
* on kernels from 2.6.26 to 3.3.
*
* WARNING: THIS WILL LIKELY HARDHANG SYSTEMS AND MAY LOSE DATA
* RUN AT YOUR OWN RISK!
* To build:
* $ gcc leapcrash.c -o leapcrash -lrt
*/
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <sys/time.h>
#include <sys/timex.h>
#include <string.h>
#include <signal.h>
#ifdef KTEST
#include "../kselftest.h"
#else
static inline int ksft_exit_pass(void)
{
exit(0);
}
static inline int ksft_exit_fail(void)
{
exit(1);
}
#endif
/* clear NTP time_status & time_state */
int clear_time_state(void)
{
struct timex tx;
int ret;
/*
* We have to call adjtime twice here, as kernels
* prior to 6b1859dba01c7 (included in 3.5 and
* -stable), had an issue with the state machine
* and wouldn't clear the STA_INS/DEL flag directly.
*/
tx.modes = ADJ_STATUS;
tx.status = STA_PLL;
ret = adjtimex(&tx);
tx.modes = ADJ_STATUS;
tx.status = 0;
ret = adjtimex(&tx);
return ret;
}
/* Make sure we cleanup on ctrl-c */
void handler(int unused)
{
clear_time_state();
exit(0);
}
int main(void)
{
struct timex tx;
struct timespec ts;
time_t next_leap;
int count = 0;
setbuf(stdout, NULL);
signal(SIGINT, handler);
signal(SIGKILL, handler);
printf("This runs for a few minutes. Press ctrl-c to stop\n");
clear_time_state();
/* Get the current time */
clock_gettime(CLOCK_REALTIME, &ts);
/* Calculate the next possible leap second 23:59:60 GMT */
next_leap = ts.tv_sec;
next_leap += 86400 - (next_leap % 86400);
for (count = 0; count < 20; count++) {
struct timeval tv;
/* set the time to 2 seconds before the leap */
tv.tv_sec = next_leap - 2;
tv.tv_usec = 0;
if (settimeofday(&tv, NULL)) {
printf("Error: You're likely not running with proper (ie: root) permissions\n");
return ksft_exit_fail();
}
tx.modes = 0;
adjtimex(&tx);
/* hammer on adjtime w/ STA_INS */
while (tx.time.tv_sec < next_leap + 1) {
/* Set the leap second insert flag */
tx.modes = ADJ_STATUS;
tx.status = STA_INS;
adjtimex(&tx);
}
clear_time_state();
printf(".");
}
printf("[OK]\n");
return ksft_exit_pass();
}
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