1 files changed, 45 insertions, 8 deletions

diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
index 90bba9e62286..b62bb9294d0c 100644
--- 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;
 };
 
 /*
@@ -389,10 +425,11 @@ struct cgroup_subsys {
                                                   struct cgroup *cgrp);
         int (*pre_destroy)(struct cgroup_subsys *ss, struct cgroup *cgrp);
         void (*destroy)(struct cgroup_subsys *ss, struct cgroup *cgrp);
-        int (*can_attach)(struct cgroup_subsys *ss,
-                          struct cgroup *cgrp, struct task_struct *tsk);
+        int (*can_attach)(struct cgroup_subsys *ss, struct cgroup *cgrp,
+                          struct task_struct *tsk, bool threadgroup);
         void (*attach)(struct cgroup_subsys *ss, struct cgroup *cgrp,
-                        struct cgroup *old_cgrp, struct task_struct *tsk);
+                        struct cgroup *old_cgrp, struct task_struct *tsk,
+                        bool threadgroup);
         void (*fork)(struct cgroup_subsys *ss, struct task_struct *task);
         void (*exit)(struct cgroup_subsys *ss, struct task_struct *task);
         int (*populate)(struct cgroup_subsys *ss,