1 files changed, 24 insertions, 0 deletions

diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
index 2a59d3101e5d..b4f2201321cd 100644
--- a/include/linux/cgroup.h
+++ b/include/linux/cgroup.h
@@ -235,6 +235,10 @@ struct cgroup {
 
         /* For RCU-protected deletion */
         struct rcu_head rcu_head;
+
+        /* List of events which userspace want to recieve */
+        struct list_head event_list;
+        spinlock_t event_list_lock;
 };
 
 /*
@@ -378,6 +382,26 @@ struct cftype {
         int (*trigger)(struct cgroup *cgrp, unsigned int event);
 
         int (*release)(struct inode *inode, struct file *file);
+
+        /*
+         * register_event() callback will be used to add new userspace
+         * waiter for changes related to the cftype. Implement it if
+         * you want to provide this functionality. Use eventfd_signal()
+         * on eventfd to send notification to userspace.
+         */
+        int (*register_event)(struct cgroup *cgrp, struct cftype *cft,
+                        struct eventfd_ctx *eventfd, const char *args);
+        /*
+         * unregister_event() callback will be called when userspace
+         * closes the eventfd or on cgroup removing.
+         * This callback must be implemented, if you want provide
+         * notification functionality.
+         *
+         * Be careful. It can be called after destroy(), so you have
+         * to keep all nesessary data, until all events are removed.
+         */
+        int (*unregister_event)(struct cgroup *cgrp, struct cftype *cft,
+                        struct eventfd_ctx *eventfd);
 };
 
 struct cgroup_scanner {