cregit-Linux how code gets into the kernel

Release 4.7 tools/testing/selftests/timers/change_skew.c

/* ADJ_FREQ Skew change test
 *              by: john stultz (johnstul@us.ibm.com)
 *              (C) Copyright IBM 2012
 *              Licensed under the GPLv2
 *
 *  NOTE: This is a meta-test which cranks the ADJ_FREQ knob and
 *  then uses other tests to detect problems. Thus this test requires
 *  that the raw_skew, inconsistency-check and nanosleep tests be
 *  present in the same directory it is run from.
 *
 *  To build:
 *      $ gcc change_skew.c -o change_skew -lrt
 *
 *   This program is free software: you can redistribute it and/or modify
 *   it under the terms of the GNU General Public License as published by
 *   the Free Software Foundation, either version 2 of the License, or
 *   (at your option) any later version.
 *
 *   This program is distributed in the hope that it will be useful,
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *   GNU General Public License for more details.
 */


#include <stdio.h>
#include <stdlib.h>
#include <sys/time.h>
#include <sys/timex.h>
#include <time.h>
#ifdef KTEST
#include "../kselftest.h"
#else

static inline int ksft_exit_pass(void) { exit(0); }

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static inline int ksft_exit_fail(void) { exit(1); }

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#endif #define NSEC_PER_SEC 1000000000LL
int change_skew_test(int ppm) { struct timex tx; int ret; tx.modes = ADJ_FREQUENCY; tx.freq = ppm << 16; ret = adjtimex(&tx); if (ret < 0) { printf("Error adjusting freq\n"); return ret; } ret = system("./raw_skew"); ret |= system("./inconsistency-check"); ret |= system("./nanosleep"); return ret; }

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int main(int argv, char **argc) { struct timex tx; int i, ret; int ppm[5] = {0, 250, 500, -250, -500}; /* Kill ntpd */ ret = system("killall -9 ntpd"); /* Make sure there's no offset adjustment going on */ tx.modes = ADJ_OFFSET; tx.offset = 0; ret = adjtimex(&tx); if (ret < 0) { printf("Maybe you're not running as root?\n"); return -1; } for (i = 0; i < 5; i++) { printf("Using %i ppm adjustment\n", ppm[i]); ret = change_skew_test(ppm[i]); if (ret) break; } /* Set things back */ tx.modes = ADJ_FREQUENCY; tx.offset = 0; adjtimex(&tx); if (ret) { printf("[FAIL]"); return ksft_exit_fail(); } printf("[OK]"); return ksft_exit_pass(); }

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john stultzjohn stultz306100.00%1100.00%
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