1 files changed, 19 insertions, 0 deletions

diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
index 058371c5d360..0a3ab670dd2f 100644
--- a/include/linux/cgroup.h
+++ b/include/linux/cgroup.h
@@ -166,6 +166,16 @@ struct css_set {
 
 };
 
+/*
+ * cgroup_map_cb is an abstract callback API for reporting map-valued
+ * control files
+ */
+
+struct cgroup_map_cb {
+        int (*fill)(struct cgroup_map_cb *cb, const char *key, u64 value);
+        void *state;
+};
+
 /* struct cftype:
  *
  * The files in the cgroup filesystem mostly have a very simple read/write
@@ -194,6 +204,15 @@ struct cftype {
          * single integer. Use it in place of read()
          */
         u64 (*read_u64) (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);
+
         ssize_t (*write) (struct cgroup *cgrp, struct cftype *cft,
                           struct file *file,
                           const char __user *buf, size_t nbytes, loff_t *ppos);