cgroup: document what the various masks variables are used for

diff --git a/src/core/unit.h b/src/core/unit.h
index 15cd02e..180f852 100644 (file)
--- a/src/core/unit.h
+++ b/src/core/unit.h
@@ -247,11 +247,11 @@ typedef struct Unit {
 
         /* Counterparts in the cgroup filesystem */
         char *cgroup_path;
-        CGroupMask cgroup_realized_mask;
-        CGroupMask cgroup_enabled_mask;
-        CGroupMask cgroup_invalidated_mask;
+        CGroupMask cgroup_realized_mask;           /* In which hierarchies does this unit's cgroup exist? (only relevant on cgroupsv1) */
+        CGroupMask cgroup_enabled_mask;            /* Which controllers are enabled (or more correctly: enabled for the children) for this unit's cgroup? (only relevant on cgroupsv2) */
+        CGroupMask cgroup_invalidated_mask;        /* A mask specifiying controllers which shall be considered invalidated, and require re-realization */
         CGroupMask cgroup_subtree_mask;
-        CGroupMask cgroup_members_mask;
+        CGroupMask cgroup_members_mask;            /* A cache for the controllers required by all children of this cgroup (only relevant for slice units) */
         int cgroup_inotify_wd;
 
         /* Device Controller BPF program */