cgroups: change css_set freeing mechanism to be under RCU

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

diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
index 90bba9e622864b88156638d231476a7889e4b125..3ac78a2f4b5a72eb259177c7ddac5f85dd70493a 100644 (file)
--- a/include/linux/cgroup.h
+++ b/include/linux/cgroup.h
@@ -141,6 +141,38 @@ enum {
        CGRP_WAIT_ON_RMDIR,
 };
 
+/* which pidlist file are we talking about? */
+enum cgroup_filetype {
+       CGROUP_FILE_PROCS,
+       CGROUP_FILE_TASKS,
+};
+
+/*
+ * A pidlist is a list of pids that virtually represents the contents of one
+ * of the cgroup files ("procs" or "tasks"). We keep a list of such pidlists,
+ * a pair (one each for procs, tasks) for each pid namespace that's relevant
+ * to the cgroup.
+ */
+struct cgroup_pidlist {
+       /*
+        * used to find which pidlist is wanted. doesn't change as long as
+        * this particular list stays in the list.
+        */
+       struct { enum cgroup_filetype type; struct pid_namespace *ns; } key;
+       /* array of xids */
+       pid_t *list;
+       /* how many elements the above list has */
+       int length;
+       /* how many files are using the current array */
+       int use_count;
+       /* each of these stored in a list by its cgroup */
+       struct list_head links;
+       /* pointer to the cgroup we belong to, for list removal purposes */
+       struct cgroup *owner;
+       /* protects the other fields */
+       struct rw_semaphore mutex;
+};
+
 struct cgroup {
        unsigned long flags;            /* "unsigned long" so bitops work */
 
@@ -179,11 +211,12 @@ struct cgroup {
         */
        struct list_head release_list;
 
-       /* pids_mutex protects pids_list and cached pid arrays. */
-       struct rw_semaphore pids_mutex;
-
-       /* Linked list of struct cgroup_pids */
-       struct list_head pids_list;
+       /*
+        * list of pidlists, up to two for each namespace (one for procs, one
+        * for tasks); created on demand.
+        */
+       struct list_head pidlists;
+       struct mutex pidlist_mutex;
 
        /* For RCU-protected deletion */
        struct rcu_head rcu_head;
@@ -227,6 +260,9 @@ struct css_set {
         * during subsystem registration (at boot time).
         */
        struct cgroup_subsys_state *subsys[CGROUP_SUBSYS_COUNT];
+
+       /* For RCU-protected deletion */
+       struct rcu_head rcu_head;
 };
 
 /*