selftests/timers: Add clocksource-switch test from timetest suite

Adds the clocksource-switch tests which continually switches the
current clocksource between all the available ones, watching for
any 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 skew_consistency
+	alarmtimer-suspend change_skew skew_consistency clocksource-switch \
 
 all: ${bins}
 
@@ -28,6 +28,7 @@ run_destructive_tests: run_tests
 	./valid-adjtimex
 	./change_skew
 	./skew_consistency
+	./clocksource-switch
 
 clean:
 	rm -f ${bins}

tools/testing/selftests/timers/clocksource-switch.c

+/* Clocksource change test
+ *		by: john stultz (johnstul@us.ibm.com)
+ *		(C) Copyright IBM 2012
+ *		Licensed under the GPLv2
+ *
+ *  NOTE: This is a meta-test which quickly changes the clocksourc and
+ *  then uses other tests to detect problems. Thus this test requires
+ *  that the inconsistency-check and nanosleep tests be present in the
+ *  same directory it is run from.
+ *
+ *  To build:
+ *	$ gcc clocksource-switch.c -o clocksource-switch -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 <sys/time.h>
+#include <sys/timex.h>
+#include <time.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.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
+
+
+int get_clocksources(char list[][30])
+{
+	int fd, i;
+	size_t size;
+	char buf[512];
+	char *head, *tmp;
+
+	fd = open("/sys/devices/system/clocksource/clocksource0/available_clocksource", O_RDONLY);
+
+	size = read(fd, buf, 512);
+
+	close(fd);
+
+	for (i = 0; i < 30; i++)
+		list[i][0] = '\0';
+
+	head = buf;
+	i = 0;
+	while (head - buf < size) {
+		/* Find the next space */
+		for (tmp = head; *tmp != ' '; tmp++) {
+			if (*tmp == '\n')
+				break;
+			if (*tmp == '\0')
+				break;
+		}
+		*tmp = '\0';
+		strcpy(list[i], head);
+		head = tmp + 1;
+		i++;
+	}
+
+	return i-1;
+}
+
+int get_cur_clocksource(char *buf, size_t size)
+{
+	int fd;
+
+	fd = open("/sys/devices/system/clocksource/clocksource0/current_clocksource", O_RDONLY);
+
+	size = read(fd, buf, size);
+
+	return 0;
+}
+
+int change_clocksource(char *clocksource)
+{
+	int fd;
+	size_t size;
+
+	fd = open("/sys/devices/system/clocksource/clocksource0/current_clocksource", O_WRONLY);
+
+	if (fd < 0)
+		return -1;
+
+	size = write(fd, clocksource, strlen(clocksource));
+
+	if (size < 0)
+		return -1;
+
+	close(fd);
+	return 0;
+}
+
+
+int run_tests(int secs)
+{
+	int ret;
+	char buf[255];
+
+	sprintf(buf, "./inconsistency-check -t %i", secs);
+	ret = system(buf);
+	if (ret)
+		return ret;
+	ret = system("./nanosleep");
+	return ret;
+}
+
+
+char clocksource_list[10][30];
+
+int main(int argv, char **argc)
+{
+	char orig_clk[512];
+	int count, i, status;
+	pid_t pid;
+
+	get_cur_clocksource(orig_clk, 512);
+
+	count = get_clocksources(clocksource_list);
+
+	if (change_clocksource(clocksource_list[0])) {
+		printf("Error: You probably need to run this as root\n");
+		return -1;
+	}
+
+	/* Check everything is sane before we start switching asyncrhonously */
+	for (i = 0; i < count; i++) {
+		printf("Validating clocksource %s\n", clocksource_list[i]);
+		if (change_clocksource(clocksource_list[i])) {
+			status = -1;
+			goto out;
+		}
+		if (run_tests(5)) {
+			status = -1;
+			goto out;
+		}
+	}
+
+
+	printf("Running Asyncrhonous Switching Tests...\n");
+	pid = fork();
+	if (!pid)
+		return run_tests(60);
+
+	while (pid != waitpid(pid, &status, WNOHANG))
+		for (i = 0; i < count; i++)
+			if (change_clocksource(clocksource_list[i])) {
+				status = -1;
+				goto out;
+			}
+out:
+	change_clocksource(orig_clk);
+
+	if (status)
+		return ksft_exit_fail();
+	return ksft_exit_pass();
+}