selftests/timers: Add inconsistency-check test from timetests

This adds my inconsistency-test from my timetests suite,
which checks for (single threaded) time inconsistencies
across the various clockids.

Cc: Shuah Khan <[e-mail]>
Cc: Prarit Bhargava <[e-mail]>
Cc: Thomas Gleixner <[e-mail]>
Cc: Richard Cochran <[e-mail]>
Signed-off-by: John Stultz <[e-mail]>
Tested-by: Prarit Bhargava <[e-mail]>
Signed-off-by: Shuah Khan <[e-mail]>

tools/testing/selftests/timers/Makefile

···
 BUILD_FLAGS = -DKTEST
 CFLAGS += -O3 -Wl,-no-as-needed -Wall $(BUILD_FLAGS)
 LDFLAGS += -lrt -lpthread
-bins = posix_timers nanosleep
+bins = posix_timers nanosleep inconsistency-check
 
 all: ${bins}
 
 run_tests: all
 	./posix_timers
 	./nanosleep
-
+	./inconsistency-check
 clean:
 	rm -f ${bins}

tools/testing/selftests/timers/inconsistency-check.c

···
+/* Time inconsistency check test
+ *		by: john stultz ([e-mail])
+ *		(C) Copyright IBM 2003, 2004, 2005, 2012
+ *		(C) Copyright Linaro Limited 2015
+ *		Licensed under the GPLv2
+ *
+ *  To build:
+ *	$ gcc inconsistency-check.c -o inconsistency-check -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 <unistd.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
+
+#define CALLS_PER_LOOP 64
+#define NSEC_PER_SEC 1000000000ULL
+
+#define CLOCK_REALTIME			0
+#define CLOCK_MONOTONIC			1
+#define CLOCK_PROCESS_CPUTIME_ID	2
+#define CLOCK_THREAD_CPUTIME_ID		3
+#define CLOCK_MONOTONIC_RAW		4
+#define CLOCK_REALTIME_COARSE		5
+#define CLOCK_MONOTONIC_COARSE		6
+#define CLOCK_BOOTTIME			7
+#define CLOCK_REALTIME_ALARM		8
+#define CLOCK_BOOTTIME_ALARM		9
+#define CLOCK_HWSPECIFIC		10
+#define CLOCK_TAI			11
+#define NR_CLOCKIDS			12
+
+char *clockstring(int clockid)
+{
+	switch (clockid) {
+	case CLOCK_REALTIME:
+		return "CLOCK_REALTIME";
+	case CLOCK_MONOTONIC:
+		return "CLOCK_MONOTONIC";
+	case CLOCK_PROCESS_CPUTIME_ID:
+		return "CLOCK_PROCESS_CPUTIME_ID";
+	case CLOCK_THREAD_CPUTIME_ID:
+		return "CLOCK_THREAD_CPUTIME_ID";
+	case CLOCK_MONOTONIC_RAW:
+		return "CLOCK_MONOTONIC_RAW";
+	case CLOCK_REALTIME_COARSE:
+		return "CLOCK_REALTIME_COARSE";
+	case CLOCK_MONOTONIC_COARSE:
+		return "CLOCK_MONOTONIC_COARSE";
+	case CLOCK_BOOTTIME:
+		return "CLOCK_BOOTTIME";
+	case CLOCK_REALTIME_ALARM:
+		return "CLOCK_REALTIME_ALARM";
+	case CLOCK_BOOTTIME_ALARM:
+		return "CLOCK_BOOTTIME_ALARM";
+	case CLOCK_TAI:
+		return "CLOCK_TAI";
+	};
+	return "UNKNOWN_CLOCKID";
+}
+
+/* returns 1 if a <= b, 0 otherwise */
+static inline int in_order(struct timespec a, struct timespec b)
+{
+	/* use unsigned to avoid false positives on 2038 rollover */
+	if ((unsigned long)a.tv_sec < (unsigned long)b.tv_sec)
+		return 1;
+	if ((unsigned long)a.tv_sec > (unsigned long)b.tv_sec)
+		return 0;
+	if (a.tv_nsec > b.tv_nsec)
+		return 0;
+	return 1;
+}
+
+
+
+int consistency_test(int clock_type, unsigned long seconds)
+{
+	struct timespec list[CALLS_PER_LOOP];
+	int i, inconsistent;
+	long now, then;
+	time_t t;
+	char *start_str;
+
+	clock_gettime(clock_type, &list[0]);
+	now = then = list[0].tv_sec;
+
+	/* timestamp start of test */
+	t = time(0);
+	start_str = ctime(&t);
+
+	while (seconds == -1 || now - then < seconds) {
+		inconsistent = 0;
+
+		/* Fill list */
+		for (i = 0; i < CALLS_PER_LOOP; i++)
+			clock_gettime(clock_type, &list[i]);
+
+		/* Check for inconsistencies */
+		for (i = 0; i < CALLS_PER_LOOP - 1; i++)
+			if (!in_order(list[i], list[i+1]))
+				inconsistent = i;
+
+		/* display inconsistency */
+		if (inconsistent) {
+			unsigned long long delta;
+
+			printf("\%s\n", start_str);
+			for (i = 0; i < CALLS_PER_LOOP; i++) {
+				if (i == inconsistent)
+					printf("--------------------\n");
+				printf("%lu:%lu\n", list[i].tv_sec,
+							list[i].tv_nsec);
+				if (i == inconsistent + 1)
+					printf("--------------------\n");
+			}
+			delta = list[inconsistent].tv_sec * NSEC_PER_SEC;
+			delta += list[inconsistent].tv_nsec;
+			delta -= list[inconsistent+1].tv_sec * NSEC_PER_SEC;
+			delta -= list[inconsistent+1].tv_nsec;
+			printf("Delta: %llu ns\n", delta);
+			fflush(0);
+			/* timestamp inconsistency*/
+			t = time(0);
+			printf("%s\n", ctime(&t));
+			printf("[FAILED]\n");
+			return -1;
+		}
+		now = list[0].tv_sec;
+	}
+	printf("[OK]\n");
+	return 0;
+}
+
+
+int main(int argc, char *argv[])
+{
+	int clockid, opt;
+	int userclock = CLOCK_REALTIME;
+	int maxclocks = NR_CLOCKIDS;
+	int runtime = 30;
+	struct timespec ts;
+
+	/* Process arguments */
+	while ((opt = getopt(argc, argv, "t:c:")) != -1) {
+		switch (opt) {
+		case 't':
+			runtime = atoi(optarg);
+			break;
+		case 'c':
+			userclock = atoi(optarg);
+			maxclocks = userclock + 1;
+			break;
+		default:
+			printf("Usage: %s [-t <secs>] [-c <clockid>]\n", argv[0]);
+			printf("	-t: Number of seconds to run\n");
+			printf("	-c: clockid to use (default, all clockids)\n");
+			exit(-1);
+		}
+	}
+
+	setbuf(stdout, NULL);
+
+	for (clockid = userclock; clockid < maxclocks; clockid++) {
+
+		if (clockid == CLOCK_HWSPECIFIC)
+			continue;
+
+		if (!clock_gettime(clockid, &ts)) {
+			printf("Consistent %-30s ", clockstring(clockid));
+			if (consistency_test(clockid, runtime))
+				return ksft_exit_fail();
+		}
+	}
+	return ksft_exit_pass();
+}