nspawn: check env var first, detect second

If we are going to use the env var to override the detection result
anyway, there is not point in doing the detection, especially that
it can fail.

diff --git a/src/nspawn/nspawn.c b/src/nspawn/nspawn.c
index a08377b3a3e3d9eeaf3dc1c7866971dc535956eb..4ce0e2e0c1b25fba84c6eac86ab7d2d32ba8d986 100644 (file)
--- a/src/nspawn/nspawn.c
+++ b/src/nspawn/nspawn.c
@@ -320,13 +320,6 @@ static int detect_unified_cgroup_hierarchy(void) {
         const char *e;
         int r, all_unified, systemd_unified;
 
-        all_unified = cg_all_unified();
-        systemd_unified = cg_unified(SYSTEMD_CGROUP_CONTROLLER);
-
-        if (all_unified < 0 || systemd_unified < 0)
-                return log_error_errno(all_unified < 0 ? all_unified : systemd_unified,
-                                       "Failed to determine whether the unified cgroups hierarchy is used: %m");
-
         /* Allow the user to control whether the unified hierarchy is used */
         e = getenv("UNIFIED_CGROUP_HIERARCHY");
         if (e) {
@@ -341,6 +334,13 @@ static int detect_unified_cgroup_hierarchy(void) {
                 return 0;
         }
 
+        all_unified = cg_all_unified();
+        systemd_unified = cg_unified(SYSTEMD_CGROUP_CONTROLLER);
+
+        if (all_unified < 0 || systemd_unified < 0)
+                return log_error_errno(all_unified < 0 ? all_unified : systemd_unified,
+                                       "Failed to determine whether the unified cgroups hierarchy is used: %m");
+
         /* Otherwise inherit the default from the host system */
         if (all_unified > 0)
                 arg_unified_cgroup_hierarchy = CGROUP_UNIFIED_ALL;