selftests/timers: Add skew_consistency test from the timetests suite

This change adds the skew_consistency test, which twists the
ADJ_FREQUENCY knob back and forth and watches for timekeeping
inconsistencies.

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 change_skew
+	alarmtimer-suspend change_skew skew_consistency
 
 all: ${bins}
 
@@ -27,6 +27,7 @@ run_destructive_tests: run_tests
 	./alarmtimer-suspend
 	./valid-adjtimex
 	./change_skew
+	./skew_consistency
 
 clean:
 	rm -f ${bins}

tools/testing/selftests/timers/skew_consistency.c

+/* ADJ_FREQ Skew consistency 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 back
+ *  and forth and watches for consistency problems. Thus this test requires
+ *  that the inconsistency-check tests be present in the same directory it
+ *  is run from.
+ *
+ *  To build:
+ *	$ gcc skew_consistency.c -o skew_consistency -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 <unistd.h>
+#include <sys/time.h>
+#include <sys/timex.h>
+#include <time.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/wait.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 main(int argv, char **argc)
+{
+	struct timex tx;
+	int ret, ppm;
+	pid_t pid;
+
+
+	printf("Running Asyncrhonous Frequency Changing Tests...\n");
+
+	pid = fork();
+	if (!pid)
+		return system("./inconsistency-check -c 1 -t 600");
+
+	ppm = 500;
+	ret = 0;
+
+	while (pid != waitpid(pid, &ret, WNOHANG)) {
+		ppm = -ppm;
+		tx.modes = ADJ_FREQUENCY;
+		tx.freq = ppm << 16;
+		adjtimex(&tx);
+		usleep(500000);
+	}
+
+	/* Set things back */
+	tx.modes = ADJ_FREQUENCY;
+	tx.offset = 0;
+	adjtimex(&tx);
+
+
+	if (ret) {
+		printf("[FAILED]\n");
+		return ksft_exit_fail();
+	}
+	printf("[OK]\n");
+	return ksft_exit_pass();
+}