selftests/timers: Add change_skew test from timetest suite

This patch adds the change_skew test which validates the
adjtimex freq can be set to various values and then using
the inconsistency-check, raw_skew, and nanosleep tests
ensures time behaves properly.

Cc: Shuah Khan <shuahkh@osg.samsung.com>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Richard Cochran <richardcochran@gmail.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Tested-by: Prarit Bhargava <prarit@redhat.com>
Signed-off-by: Shuah Khan <shuahkh@osg.samsung.com>

tools/testing/selftests/timers/Makefile

@@ -4,7 +4,7 @@ CFLAGS += -O3 -Wl,-no-as-needed -Wall $(BUILD_FLAGS)
 LDFLAGS += -lrt -lpthread
 bins = posix_timers nanosleep inconsistency-check nsleep-lat raw_skew \
 	set-timer-lat threadtest mqueue-lat valid-adjtimex \
-	alarmtimer-suspend
+	alarmtimer-suspend change_skew
 
 all: ${bins}
 
@@ -26,6 +26,7 @@ run_tests: all
 run_destructive_tests: run_tests
 	./alarmtimer-suspend
 	./valid-adjtimex
+	./change_skew
 
 clean:
 	rm -f ${bins}

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