text: /* 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();
  }
  