[PATCH v3 06/21] selftests/resctrl: Check for resctrl mount point only if resctrl FS is supported

[Fenghua Yu]

check_resctrlfs_support() does the following
1. Checks if the platform supports resctrl file system or not by looking
   for resctrl in /proc/filesystems
2. Calls opendir() on default resctrl file system path
   (i.e. /sys/fs/resctrl)
3. Checks if resctrl file system is mounted or not by looking at
   /proc/mounts

Steps 2 and 3 will fail if the platform does not support resctrl file
system. So, there is no need to check for them if step 1 fails.

Fix this by returning immediately if the platform does not support
resctrl file system.

Fixes: ecdbb911f22d ("selftests/resctrl: Add MBM test")
Signed-off-by: Fenghua Yu <fenghua.yu@xxxxxxxxx>
---
 tools/testing/selftests/resctrl/resctrlfs.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/tools/testing/selftests/resctrl/resctrlfs.c b/tools/testing/selftests/resctrl/resctrlfs.c
index 727e667e2cc9..e43ddebd1aa4 100644
--- a/tools/testing/selftests/resctrl/resctrlfs.c
+++ b/tools/testing/selftests/resctrl/resctrlfs.c
@@ -581,6 +581,9 @@ bool check_resctrlfs_support(void)
 	printf("%sok kernel supports resctrl filesystem\n", ret ? "" : "not ");
 	tests_run++;
 
+	if (!ret)
+		return ret;
+
 	dp = opendir(RESCTRL_PATH);
 	printf("%sok resctrl mountpoint \"%s\" exists\n",
 	       dp ? "" : "not ", RESCTRL_PATH);
-- 
2.29.0