[PATCH v4 05/19] selftests/resctrl: Unmount resctrl FS before starting the first test

["Ilpo Järvinen" <ilpo.jarvinen@linux.intel.com>]

Resctrl FS mount/remount/umount code is hard to track. Better approach
is to use mount/umount pair for each test but that assumes resctrl FS
is not mounted beforehand.

Change umount_resctrlfs() so that it can unmount resctrl FS from any
path, and enable further simplifications into mount/remount/umount
logic by unmounting resctrl FS at the start if a pre-existing
mountpoint is found.

Suggested-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
---
 tools/testing/selftests/resctrl/resctrl_tests.c | 2 ++
 tools/testing/selftests/resctrl/resctrlfs.c     | 6 ++++--
 2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/tools/testing/selftests/resctrl/resctrl_tests.c b/tools/testing/selftests/resctrl/resctrl_tests.c
index 9b9751206e1c..b1b2d28b52f7 100644
--- a/tools/testing/selftests/resctrl/resctrl_tests.c
+++ b/tools/testing/selftests/resctrl/resctrl_tests.c
@@ -250,6 +250,8 @@ int main(int argc, char **argv)
 	if (!check_resctrlfs_support())
 		return ksft_exit_skip("resctrl FS does not exist. Enable X86_CPU_RESCTRL config option.\n");
 
+	umount_resctrlfs();
+
 	filter_dmesg();
 
 	ksft_set_plan(tests ? : 4);
diff --git a/tools/testing/selftests/resctrl/resctrlfs.c b/tools/testing/selftests/resctrl/resctrlfs.c
index fb00245dee92..23f75aeaa198 100644
--- a/tools/testing/selftests/resctrl/resctrlfs.c
+++ b/tools/testing/selftests/resctrl/resctrlfs.c
@@ -82,10 +82,12 @@ int remount_resctrlfs(bool mum_resctrlfs)
 
 int umount_resctrlfs(void)
 {
-	if (find_resctrl_mount(NULL))
+	char mountpoint[256];
+
+	if (find_resctrl_mount(mountpoint))
 		return 0;
 
-	if (umount(RESCTRL_PATH)) {
+	if (umount(mountpoint)) {
 		perror("# Unable to umount resctrl");
 
 		return errno;
-- 
2.30.2