cgroup: don't print subsystems for the default hierarchy
It doesn't make sense to print subsystems on mount option or
/proc/PID/cgroup for the default hierarchy.
* cgroup.controllers file at the root of the default hierarchy lists
the currently attached controllers.
* The default hierarchy is catch-all for unmounted subsystems.
* The default hierarchy doesn't accept any mount options.
Suppress subsystem printing on mount options and /proc/PID/cgroup for
the default hierarchy.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: cgroups@vger.kernel.org
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 3f66416..d9f854d 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -1333,9 +1333,10 @@
struct cgroup_subsys *ss;
int ssid;
- for_each_subsys(ss, ssid)
- if (root->subsys_mask & (1 << ssid))
- seq_printf(seq, ",%s", ss->name);
+ if (root != &cgrp_dfl_root)
+ for_each_subsys(ss, ssid)
+ if (root->subsys_mask & (1 << ssid))
+ seq_printf(seq, ",%s", ss->name);
if (root->flags & CGRP_ROOT_NOPREFIX)
seq_puts(seq, ",noprefix");
if (root->flags & CGRP_ROOT_XATTR)
@@ -5137,9 +5138,11 @@
continue;
seq_printf(m, "%d:", root->hierarchy_id);
- for_each_subsys(ss, ssid)
- if (root->subsys_mask & (1 << ssid))
- seq_printf(m, "%s%s", count++ ? "," : "", ss->name);
+ if (root != &cgrp_dfl_root)
+ for_each_subsys(ss, ssid)
+ if (root->subsys_mask & (1 << ssid))
+ seq_printf(m, "%s%s", count++ ? "," : "",
+ ss->name);
if (strlen(root->name))
seq_printf(m, "%sname=%s", count ? "," : "",
root->name);
