+ u64 (*read_u64)(struct cgroup *cgrp, struct cftype *cft);
+ /*
+ * read_s64() is a signed version of read_u64()
+ */
+ s64 (*read_s64)(struct cgroup *cgrp, struct cftype *cft);
+ /*
+ * read_map() is used for defining a map of key/value
+ * pairs. It should call cb->fill(cb, key, value) for each
+ * entry. The key/value pairs (and their ordering) should not
+ * change between reboots.
+ */
+ int (*read_map)(struct cgroup *cont, struct cftype *cft,
+ struct cgroup_map_cb *cb);
+ /*
+ * read_seq_string() is used for outputting a simple sequence
+ * using seqfile.
+ */
+ int (*read_seq_string)(struct cgroup *cont, struct cftype *cft,
+ struct seq_file *m);
+
+ ssize_t (*write)(struct cgroup *cgrp, struct cftype *cft,
+ struct file *file,
+ const char __user *buf, size_t nbytes, loff_t *ppos);
+
+ /*
+ * write_u64() is a shortcut for the common case of accepting
+ * a single integer (as parsed by simple_strtoull) from
+ * userspace. Use in place of write(); return 0 or error.
+ */
+ int (*write_u64)(struct cgroup *cgrp, struct cftype *cft, u64 val);
+ /*
+ * write_s64() is a signed version of write_u64()
+ */
+ int (*write_s64)(struct cgroup *cgrp, struct cftype *cft, s64 val);
+
+ /*
+ * write_string() is passed a nul-terminated kernelspace
+ * buffer of maximum length determined by max_write_len.
+ * Returns 0 or -ve error code.
+ */
+ int (*write_string)(struct cgroup *cgrp, struct cftype *cft,
+ const char *buffer);
+ /*
+ * trigger() callback can be used to get some kick from the
+ * userspace, when the actual string written is not important
+ * at all. The private field can be used to determine the
+ * kick type for multiplexing.
+ */
+ 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.
+ */
+ int (*unregister_event)(struct cgroup *cgrp, struct cftype *cft,
+ struct eventfd_ctx *eventfd);