selftests/resctrl: Reorder resctrl FS prep code and benchmark_cmd init

Benchmark command is initialized before resctrl FS check and
preparation code that can call ksft_exit_skip(). There is no strong
reason why the resctrl FS support check and unmounting it (if already
mounted), has to be done after the benchmark command initialization.

Move benchmark command initialization such that it is done not until
right before the tests commence. This simplifies rollback handling when
benchmark command initialization starts to use dynamic allocation (in a
change following this).
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
Reviewed-by: "Wieczor-Retman, Maciej" <maciej.wieczor-retman@intel.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

tools/testing/selftests/resctrl/resctrl_tests.c

@@ -252,6 +252,14 @@ int main(int argc, char **argv)
 	if (geteuid() != 0)
 		return ksft_exit_skip("Not running as root. Skipping...\n");
 
+	if (!check_resctrlfs_support())
+		return ksft_exit_skip("resctrl FS does not exist. Enable X86_CPU_RESCTRL config option.\n");
+
+	if (umount_resctrlfs())
+		return ksft_exit_skip("resctrl FS unmount failed.\n");
+
+	filter_dmesg();
+
 	if (has_ben) {
 		if (argc - ben_ind >= BENCHMARK_ARGS)
 			ksft_exit_fail_msg("Too long benchmark command.\n");
@@ -277,14 +285,6 @@ int main(int argc, char **argv)
 		benchmark_cmd[5] = NULL;
 	}
 
-	if (!check_resctrlfs_support())
-		return ksft_exit_skip("resctrl FS does not exist. Enable X86_CPU_RESCTRL config option.\n");
-
-	if (umount_resctrlfs())
-		return ksft_exit_skip("resctrl FS unmount failed.\n");
-
-	filter_dmesg();
-
 	ksft_set_plan(tests ? : 4);
 
 	if (mbm_test)