cgroups: fail when no cgroup hierarchies are found

src/lxc/cgroups/cgfsng.c

@@ -922,29 +922,6 @@ static int get_existing_subsystems(char ***klist, char ***nlist)
 	return 0;
 }
 
-static void lxc_cgfsng_print_hierarchies(struct cgroup_ops *ops)
-{
-	int i;
-	struct hierarchy **it;
-
-	if (!ops->hierarchies) {
-		TRACE("  No hierarchies found");
-		return;
-	}
-
-	TRACE("  Hierarchies:");
-	for (i = 0, it = ops->hierarchies; it && *it; it++, i++) {
-		int j;
-		char **cit;
-
-		TRACE("  %d: base_cgroup: %s", i, (*it)->container_base_path ? (*it)->container_base_path : "(null)");
-		TRACE("      mountpoint:  %s", (*it)->mountpoint ? (*it)->mountpoint : "(null)");
-		TRACE("      controllers:");
-		for (j = 0, cit = (*it)->controllers; cit && *cit; cit++, j++)
-			TRACE("      %d: %s", j, *cit);
-	}
-}
-
 static void lxc_cgfsng_print_basecg_debuginfo(char *basecginfo, char **klist,
 					      char **nlist)
 {
@@ -3465,9 +3442,6 @@ static int cg_hybrid_init(struct cgroup_ops *ops, bool relative, bool unprivileg
 		}
 	}
 
-	TRACE("Writable cgroup hierarchies:");
-	lxc_cgfsng_print_hierarchies(ops);
-
 	/* verify that all controllers in cgroup.use and all crucial
 	 * controllers are accounted for
 	 */

src/lxc/cgroups/cgroup.c

@@ -33,10 +33,14 @@ struct cgroup_ops *cgroup_init(struct lxc_conf *conf)
 	if (!cgroup_ops)
 		return log_error_errno(NULL, errno, "Failed to initialize cgroup driver");
 
+	if (!cgroup_ops->hierarchies) {
+		cgroup_exit(cgroup_ops);
+		return log_error_errno(NULL, ENOENT, "No cgroup hierarchies found");
+	}
+
 	if (cgroup_ops->data_init(cgroup_ops)) {
 		cgroup_exit(cgroup_ops);
-		return log_error_errno(NULL, errno,
-				       "Failed to initialize cgroup data");
+		return log_error_errno(NULL, errno, "Failed to initialize cgroup data");
 	}
 
 	TRACE("Initialized cgroup driver %s", cgroup_ops->driver);