1 files changed, 21 insertions, 7 deletions

diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
index 665fa70e4094..90bba9e62286 100644
--- a/include/linux/cgroup.h
+++ b/include/linux/cgroup.h
@@ -179,14 +179,11 @@ struct cgroup {
          */
         struct list_head release_list;
 
-        /* pids_mutex protects the fields below */
+        /* pids_mutex protects pids_list and cached pid arrays. */
         struct rw_semaphore pids_mutex;
-        /* Array of process ids in the cgroup */
-        pid_t *tasks_pids;
-        /* How many files are using the current tasks_pids array */
-        int pids_use_count;
-        /* Length of the current tasks_pids array */
-        int pids_length;
+
+        /* Linked list of struct cgroup_pids */
+        struct list_head pids_list;
 
         /* For RCU-protected deletion */
         struct rcu_head rcu_head;
@@ -366,6 +363,23 @@ int cgroup_task_count(const struct cgroup *cgrp);
 int cgroup_is_descendant(const struct cgroup *cgrp, struct task_struct *task);
 
 /*
+ * When the subsys has to access css and may add permanent refcnt to css,
+ * it should take care of racy conditions with rmdir(). Following set of
+ * functions, is for stop/restart rmdir if necessary.
+ * Because these will call css_get/put, "css" should be alive css.
+ *
+ *  cgroup_exclude_rmdir();
+ *  ...do some jobs which may access arbitrary empty cgroup
+ *  cgroup_release_and_wakeup_rmdir();
+ *
+ *  When someone removes a cgroup while cgroup_exclude_rmdir() holds it,
+ *  it sleeps and cgroup_release_and_wakeup_rmdir() will wake him up.
+ */
+
+void cgroup_exclude_rmdir(struct cgroup_subsys_state *css);
+void cgroup_release_and_wakeup_rmdir(struct cgroup_subsys_state *css);
+
+/*
  * Control Group subsystem type.
  * See Documentation/cgroups/cgroups.txt for details
  */