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