core: turn on memory/cpu/tasks accounting by default for the root slice

The kernel exposes the necessary data in /proc anyway, let's expose it
hence by default.

With this in place "systemctl status -- -.slice" will show accounting
data out-of-the-box now.

1 files changed, 22 insertions, 5 deletions

diff --git a/src/core/cgroup.c b/src/core/cgroup.c
index c5ca9947e..85575a589 100644
--- a/src/core/cgroup.c
+++ b/src/core/cgroup.c
@@ -37,19 +37,34 @@
 #include "stdio-util.h"
 #include "string-table.h"
 #include "string-util.h"
+//#include "virt.h"
 
 #define CGROUP_CPU_QUOTA_PERIOD_USEC ((usec_t) 100 * USEC_PER_MSEC)
 
+bool manager_owns_root_cgroup(Manager *m) {
+        assert(m);
+
+        /* Returns true if we are managing the root cgroup. Note that it isn't sufficient to just check whether the
+         * group root path equals "/" since that will also be the case if CLONE_NEWCGROUP is in the mix. Since there's
+         * appears to be no nice way to detect whether we are in a CLONE_NEWCGROUP namespace we instead just check if
+         * we run in any kind of container virtualization. */
+
+        if (detect_container() > 0)
+                return false;
+
+        return isempty(m->cgroup_root) || path_equal(m->cgroup_root, "/");
+}
+
 bool unit_has_root_cgroup(Unit *u) {
         assert(u);
 
-        /* Returns whether this unit manages the root cgroup. Note that this is different from being named "-.slice",
-         * as inside of containers the root slice won't be identical to the root cgroup. */
+        /* Returns whether this unit manages the root cgroup. This will return true if this unit is the root slice and
+         * the manager manages the root cgroup. */
 
-        if (!u->cgroup_path)
+        if (!manager_owns_root_cgroup(u->manager))
                 return false;
 
-        return isempty(u->cgroup_path) || path_equal(u->cgroup_path, "/");
+        return unit_has_name(u, SPECIAL_ROOT_SLICE);
 }
 
 #if 0 /// UNNEEDED by elogind
@@ -59,7 +74,9 @@ static void cgroup_compat_warn(void) {
         if (cgroup_compat_warned)
                 return;
 
-        log_warning("cgroup compatibility translation between legacy and unified hierarchy settings activated. See cgroup-compat debug messages for details.");
+        log_warning("cgroup compatibility translation between legacy and unified hierarchy settings activated. "
+                    "See cgroup-compat debug messages for details.");
+
         cgroup_compat_warned = true;
 }