[PATCH 2/2] selftests/timens: Add a test for futex()

[Andrei Vagin]

Output on success:
 $ ./futex
 1..1
 ok 1 futex
 # Totals: pass:1 fail:0 xfail:0 xpass:0 skip:0 error:0

Signed-off-by: Andrei Vagin <avagin@xxxxxxxxx>
---
 tools/testing/selftests/timens/Makefile |   2 +-
 tools/testing/selftests/timens/futex.c  | 107 ++++++++++++++++++++++++
 2 files changed, 108 insertions(+), 1 deletion(-)
 create mode 100644 tools/testing/selftests/timens/futex.c

diff --git a/tools/testing/selftests/timens/Makefile b/tools/testing/selftests/timens/Makefile
index b4fd9a934654..3a5936cc10ab 100644
--- a/tools/testing/selftests/timens/Makefile
+++ b/tools/testing/selftests/timens/Makefile
@@ -1,4 +1,4 @@
-TEST_GEN_PROGS := timens timerfd timer clock_nanosleep procfs exec
+TEST_GEN_PROGS := timens timerfd timer clock_nanosleep procfs exec futex
 TEST_GEN_PROGS_EXTENDED := gettime_perf
 
 CFLAGS := -Wall -Werror -pthread
diff --git a/tools/testing/selftests/timens/futex.c b/tools/testing/selftests/timens/futex.c
new file mode 100644
index 000000000000..173760d3fce6
--- /dev/null
+++ b/tools/testing/selftests/timens/futex.c
@@ -0,0 +1,107 @@
+// SPDX-License-Identifier: GPL-2.0
+#define _GNU_SOURCE
+#include <sched.h>
+
+#include <linux/unistd.h>
+#include <linux/futex.h>
+#include <stdlib.h>
+#include <signal.h>
+#include <stdio.h>
+#include <stdint.h>
+#include <string.h>
+#include <sys/syscall.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <time.h>
+#include <unistd.h>
+
+#include "log.h"
+#include "timens.h"
+
+#define NSEC_PER_SEC 1000000000ULL
+
+static int run_test(void)
+{
+	struct timespec timeout, end;
+	int val = 0;
+
+	clock_gettime(CLOCK_MONOTONIC, &timeout);
+	timeout.tv_nsec += NSEC_PER_SEC / 10; // 100ms
+	if (timeout.tv_nsec > NSEC_PER_SEC) {
+		timeout.tv_sec++;
+		timeout.tv_nsec -= NSEC_PER_SEC;
+	}
+
+	if (syscall(__NR_futex, &val, FUTEX_WAIT_BITSET, 0,
+		    &timeout, 0, FUTEX_BITSET_MATCH_ANY) >= 0) {
+		ksft_test_result_fail("futex didn't return ETIMEDOUT");
+		return 1;
+	}
+
+	if (errno != ETIMEDOUT) {
+		ksft_test_result_fail("futex didn't return ETIMEDOUT: %s",
+							strerror(errno));
+		return 1;
+	}
+
+	clock_gettime(CLOCK_MONOTONIC, &end);
+
+	if (end.tv_sec < timeout.tv_sec ||
+	    (end.tv_sec == timeout.tv_sec && end.tv_nsec < timeout.tv_sec)) {
+		ksft_test_result_fail("futex slept less than 100ms");
+		return 1;
+	}
+
+
+	ksft_test_result_pass("futex\n");
+
+	return 0;
+}
+
+int main(int argc, char *argv[])
+{
+	int status, len, fd;
+	char buf[4096];
+	pid_t pid;
+	struct timespec mtime_now;
+
+	nscheck();
+
+	check_supported_timers();
+
+	ksft_set_plan(1);
+
+	clock_gettime(CLOCK_MONOTONIC, &mtime_now);
+
+	if (unshare_timens())
+		return 1;
+
+	len = snprintf(buf, sizeof(buf), "%d %d 0",
+			CLOCK_MONOTONIC, 70 * 24 * 3600);
+	fd = open("/proc/self/timens_offsets", O_WRONLY);
+	if (fd < 0)
+		return pr_perror("/proc/self/timens_offsets");
+
+	if (write(fd, buf, len) != len)
+		return pr_perror("/proc/self/timens_offsets");
+
+	close(fd);
+
+	pid = fork();
+	if (pid < 0)
+		return pr_perror("Unable to fork");
+	if (pid == 0) {
+		if (run_test())
+			ksft_exit_fail();
+		ksft_exit_pass();
+		return 0;
+	}
+
+	if (waitpid(pid, &status, 0) != pid)
+		return pr_perror("Unable to wait the child process");
+
+	if (WIFEXITED(status))
+		return WEXITSTATUS(status);
+
+	return 1;
+}
-- 
2.26.2