cgroup: implement cgroup_subsys->depends_on

[deliverable/linux.git] / include / linux / cgroup.h

diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
index 8a111dd42d7aea1764f55abd385ab149fcd196f1..28853e771f3b24fd0316b7b0984b6aa77098eca4 100644 (file)
--- a/include/linux/cgroup.h
+++ b/include/linux/cgroup.h
@@ -203,7 +203,15 @@ struct cgroup {
        struct kernfs_node *kn;         /* cgroup kernfs entry */
        struct kernfs_node *populated_kn; /* kn for "cgroup.subtree_populated" */
 
-       /* the bitmask of subsystems enabled on the child cgroups */
+       /*
+        * The bitmask of subsystems enabled on the child cgroups.
+        * ->subtree_control is the one configured through
+        * "cgroup.subtree_control" while ->child_subsys_mask is the
+        * effective one which may have more subsystems enabled.
+        * Controller knobs are made available iff it's enabled in
+        * ->subtree_control.
+        */
+       unsigned int subtree_control;
        unsigned int child_subsys_mask;
 
        /* Private pointers for each registered subsystem */
@@ -634,6 +642,7 @@ struct cgroup_subsys {
        int (*css_online)(struct cgroup_subsys_state *css);
        void (*css_offline)(struct cgroup_subsys_state *css);
        void (*css_free)(struct cgroup_subsys_state *css);
+       void (*css_reset)(struct cgroup_subsys_state *css);
 
        int (*can_attach)(struct cgroup_subsys_state *css,
                          struct cgroup_taskset *tset);
@@ -684,6 +693,15 @@ struct cgroup_subsys {
 
        /* base cftypes, automatically registered with subsys itself */
        struct cftype *base_cftypes;
+
+       /*
+        * A subsystem may depend on other subsystems.  When such subsystem
+        * is enabled on a cgroup, the depended-upon subsystems are enabled
+        * together if available.  Subsystems enabled due to dependency are
+        * not visible to userland until explicitly enabled.  The following
+        * specifies the mask of subsystems that this one depends on.
+        */
+       unsigned int depends_on;
 };
 
 #define SUBSYS(_x) extern struct cgroup_subsys _x ## _cgrp_subsys;