[LTP] [PATCH 3/4] controllers/cgroup_fj: Update cgroup_fj_common to work under cgroup2

[Luke Nowakowski-Krijger]

Check under which hierachy a controller is mounted on and set
the appropriate paths and variables to be able to access it.

Signed-off-by: Luke Nowakowski-Krijger <luke.nowakowskikrijger@canonical.com>
---
 .../controllers/cgroup_fj/cgroup_fj_common.sh | 73 +++++++++++++------
 1 file changed, 50 insertions(+), 23 deletions(-)

diff --git a/testcases/kernel/controllers/cgroup_fj/cgroup_fj_common.sh b/testcases/kernel/controllers/cgroup_fj/cgroup_fj_common.sh
index 53ab637e8..6c7cb1fa5 100755
--- a/testcases/kernel/controllers/cgroup_fj/cgroup_fj_common.sh
+++ b/testcases/kernel/controllers/cgroup_fj/cgroup_fj_common.sh
@@ -48,11 +48,11 @@ attach_and_check()
 
     tst_resm TINFO "Attaching task $pid to $path"
 
-    ROD echo "$pid" \> "$path/tasks"
+    ROD echo "$pid" \> "$path/$task_list"
 
-    for task in $(cat "$path/tasks"); do
+    for task in $(cat "$path/$task_list"); do
         if [ "$task" -ne "$pid" ]; then
-            tst_resm TINFO "Unexpected pid $task in $path/tasks, expected $pid"
+            tst_resm TINFO "Unexpected pid $task in $path/$task_list, expected $pid"
             return 1
         fi
     done
@@ -68,7 +68,9 @@ create_subgroup()
 
     # cpuset.cpus and cpuset.mems must be initialized with suitable value
     # before any pids are attached
-    if [ "$subsystem" = "cpuset" ]; then
+    # Only needs to be done for cgroup v1 as sets are inherited from parents
+    # by default in cgroup v2
+    if [ "$cgroup_v" = "v1" ] && [ "$subsystem" = "cpuset" ]; then
         if [ -e "$mount_point/cpus" ]; then
             ROD cat "$mount_point/cpus" \> "$path/cpus"
             ROD cat "$mount_point/mems" \> "$path/mems"
@@ -79,6 +81,39 @@ create_subgroup()
     fi
 }
 
+setup_cgroupv2()
+{
+    mount_point=$(grep -w cgroup2 /proc/mounts | cut -f 2 | cut -d " " -f2)
+    if ! grep -q "$subsystem" "$mount_point"/cgroup.controllers; then
+        tst_resm TINFO "$subsystem controller not supported on cgroup v2."
+        return
+    fi
+
+    task_list="cgroup.procs"
+    cgroup_v="v2"
+}
+
+setup_cgroupv1()
+{
+    exist=$(grep -w "$subsystem" /proc/cgroups | cut -f1);
+    if [ "$exist" = "" ]; then
+        tst_brk TCONF NULL "$subsystem controller not supported"
+    fi
+
+    mount_point=$(grep -w "$subsystem" /proc/mounts | cut -f 2 | cut -d " " -f2)
+    if [ "$mount_point" = "" ]; then
+        cgroup_mounted=0
+	mount_point="/dev/cgroup"
+    fi
+
+    if [ "$cgroup_mounted" -eq "0" ]; then
+	ROD mkdir -p $mount_point
+	ROD mount -t cgroup -o "$subsystem" none $mount_point
+    fi
+
+    task_list="tasks"
+    cgroup_v="v1"
+}
 
 setup()
 {
@@ -94,18 +129,17 @@ setup()
     tst_tmpdir
     TST_CLEANUP=cleanup
 
-    mount_point=`grep -w $subsystem /proc/mounts | grep -w "cgroup" | \
-	cut -f 2 | cut -d " " -f2`
-
-    if [ -z "$mount_point" ]; then
-        try_umount=1
-        mount_point="/dev/cgroup"
-	tst_resm TINFO "Subsystem $subsystem is not mounted, mounting it at $mount_point"
-        ROD mkdir $mount_point
-        ROD mount -t cgroup -o "$subsystem" "ltp_cgroup" "$mount_point"
-    else
-	tst_resm TINFO "Subsystem $subsystem is mounted at $mount_point"
+    cgroup_mounted=1
+
+    if grep -q cgroup2 /proc/mounts; then
+        setup_cgroupv2
+    fi
+
+    if [ -z "$cgroup_v" ]; then
+        setup_cgroupv1
     fi
+
+    tst_resm TINFO "test starts with cgroup $cgroup_v"
 }
 
 cleanup()
@@ -118,15 +152,8 @@ cleanup()
 
     find "$mount_point/ltp/" -depth -type d -exec rmdir '{}' \;
 
-    if [ -z "$try_umount" ]; then
-	return
-    fi
-
-    if grep -q "$mount_point" /proc/mounts; then
+    if [ "$cgroup_mounted" -eq "0" ]; then
         EXPECT_PASS umount "$mount_point"
-    fi
-
-    if [ -e "$mount_point" ]; then
         EXPECT_PASS rmdir "$mount_point"
     fi
 }
-- 
2.32.0