cgroups: improve utility controller handling

src/lxc/cgroups/cgfsng.c

@@ -123,12 +123,12 @@ static struct hierarchy *get_hierarchy(struct cgroup_ops *ops, const char *contr
 		 */
 		if (pure_unified_layout(ops)) {
 			if (strequal(controller, "devices")) {
-				if (ops->unified->bpf_device_controller)
+				if (device_utility_controller(ops->unified))
 					return ops->unified;
 
 				break;
 			} else if (strequal(controller, "freezer")) {
-				if (ops->unified->freezer_controller)
+				if (freezer_utility_controller(ops->unified))
 					return ops->unified;
 
 				break;
@@ -1400,7 +1400,7 @@ __cgfsng_ops static void cgfsng_payload_finalize(struct cgroup_ops *ops)
             !faccessat(ops->unified->dfd_con, "cgroup.freeze", F_OK,
                        AT_SYMLINK_NOFOLLOW)) {
 		TRACE("Unified hierarchy supports freezer");
-		ops->unified->freezer_controller = 1;
+		ops->unified->utilities |= FREEZER_CONTROLLER;
         }
 }
 
@@ -2836,7 +2836,7 @@ __cgfsng_ops static bool cgfsng_devices_activate(struct cgroup_ops *ops, struct
 	conf = handler->conf;
 
 	unified = ops->unified;
-	if (!unified || !unified->bpf_device_controller ||
+	if (!unified || !device_utility_controller(unified) ||
 	    !unified->path_con ||
 	    lxc_list_empty(&(conf->bpf_devices).device_item))
 		return true;
@@ -3220,7 +3220,7 @@ static int __initialize_cgroups(struct cgroup_ops *ops, bool relative,
 			ops->cgroup_layout = CGROUP_LAYOUT_HYBRID;
 		} else {
 			if (bpf_devices_cgroup_supported())
-				ops->unified->bpf_device_controller = 1;
+				ops->unified->utilities |= DEVICES_CONTROLLER;
 			ops->cgroup_layout = CGROUP_LAYOUT_UNIFIED;
 		}
 	}

src/lxc/cgroups/cgroup.h

@@ -38,6 +38,9 @@ typedef enum {
 	UNIFIED_HIERARCHY = CGROUP2_SUPER_MAGIC,
 } cgroupfs_type_magic_t;
 
+#define DEVICES_CONTROLLER (1U << 0)
+#define FREEZER_CONTROLLER (1U << 1)
+
 /* A descriptor for a mounted hierarchy
  *
  * @controllers
@@ -104,13 +107,26 @@ struct hierarchy {
 
 	struct /* unified hierarchy specific */ {
 		char **delegate;
-		unsigned int bpf_device_controller : 1;
-		unsigned int freezer_controller : 1;
+		unsigned int utilities;
 	};
 
 	char **controllers;
 };
 
+static inline bool device_utility_controller(const struct hierarchy *h)
+{
+	if (h->fs_type == UNIFIED_HIERARCHY && (h->utilities & DEVICES_CONTROLLER))
+		return true;
+	return false;
+}
+
+static inline bool freezer_utility_controller(const struct hierarchy *h)
+{
+	if (h->fs_type == UNIFIED_HIERARCHY && (h->utilities & FREEZER_CONTROLLER))
+		return true;
+	return false;
+}
+
 struct cgroup_ops {
 	/* string constant */
 	const char *driver;