selftests/membarrier: Test MEMBARRIER_CMD_GET_REGISTRATIONS

Keep track of previously issued registrations and compare the result
with MEMBARRIER_CMD_GET_REGISTRATIONS return value.

Signed-off-by: Michal Clapinski <[e-mail]>
Signed-off-by: Ingo Molnar <[e-mail]>
Acked-by: Mathieu Desnoyers <[e-mail]>
Acked-by: Paul E. McKenney <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]

tools/testing/selftests/membarrier/membarrier_test_impl.h

···
 
 #include "../kselftest.h"
 
+static int registrations;
+
 static int sys_membarrier(int cmd, int flags)
 {
 	return syscall(__NR_membarrier, cmd, flags);
+}
+
+static int test_membarrier_get_registrations(int cmd)
+{
+	int ret, flags = 0;
+	const char *test_name =
+		"sys membarrier MEMBARRIER_CMD_GET_REGISTRATIONS";
+
+	registrations |= cmd;
+
+	ret = sys_membarrier(MEMBARRIER_CMD_GET_REGISTRATIONS, 0);
+	if (ret < 0) {
+		ksft_exit_fail_msg(
+			"%s test: flags = %d, errno = %d\n",
+			test_name, flags, errno);
+	} else if (ret != registrations) {
+		ksft_exit_fail_msg(
+			"%s test: flags = %d, ret = %d, registrations = %d\n",
+			test_name, flags, ret, registrations);
+	}
+	ksft_test_result_pass(
+		"%s test: flags = %d, ret = %d, registrations = %d\n",
+		test_name, flags, ret, registrations);
+
+	return 0;
 }
 
 static int test_membarrier_cmd_fail(void)
···
 	ksft_test_result_pass(
 		"%s test: flags = %d\n",
 		test_name, flags);
+
+	test_membarrier_get_registrations(cmd);
 	return 0;
 }
 
···
 	ksft_test_result_pass(
 		"%s test: flags = %d\n",
 		test_name, flags);
+
+	test_membarrier_get_registrations(cmd);
 	return 0;
 }
 
···
 	ksft_test_result_pass(
 		"%s test: flags = %d\n",
 		test_name, flags);
+
+	test_membarrier_get_registrations(cmd);
 	return 0;
 }
 

tools/testing/selftests/membarrier/membarrier_test_multi_thread.c

···
 int main(int argc, char **argv)
 {
 	ksft_print_header();
-	ksft_set_plan(13);
+	ksft_set_plan(16);
 
 	test_membarrier_query();
 

tools/testing/selftests/membarrier/membarrier_test_single_thread.c

···
 int main(int argc, char **argv)
 {
 	ksft_print_header();
-	ksft_set_plan(13);
+	ksft_set_plan(18);
+
+	test_membarrier_get_registrations(/*cmd=*/0);
 
 	test_membarrier_query();
 
 	test_membarrier_fail();
 
 	test_membarrier_success();
+
+	test_membarrier_get_registrations(/*cmd=*/0);
 
 	return ksft_exit_pass();
 }