4 files changed, 82 insertions, 52 deletions
diff --git a/Documentation/cgroups/00-INDEX b/Documentation/cgroups/00-INDEX
index 3f58fa3d6d00..f78b90a35ad0 100644
--- a/Documentation/cgroups/00-INDEX
+++ b/Documentation/cgroups/00-INDEX
@@ -1,7 +1,11 @@
 00-INDEX
 	- this file
+blkio-controller.txt
+	- Description for Block IO Controller, implementation and usage details.
 cgroups.txt
 	- Control Groups definition, implementation details, examples and API.
+cgroup_event_listener.c
+	- A user program for cgroup listener.
 cpuacct.txt
 	- CPU Accounting Controller; account CPU usage for groups of tasks.
 cpusets.txt
@@ -10,9 +14,13 @@ devices.txt
 	- Device Whitelist Controller; description, interface and security.
 freezer-subsystem.txt
 	- checkpointing; rationale to not use signals, interface.
+hugetlb.txt
+	- HugeTLB Controller implementation and usage details.
 memcg_test.txt
 	- Memory Resource Controller; implementation details.
 memory.txt
 	- Memory Resource Controller; design, accounting, interface, testing.
+net_prio.txt
+	- Network priority cgroups details and usages.
 resource_counter.txt
 	- Resource Counter API.
diff --git a/Documentation/cgroups/cgroups.txt b/Documentation/cgroups/cgroups.txt
index 9e04196c4d78..bcf1a00b06a1 100644
--- a/Documentation/cgroups/cgroups.txt
+++ b/Documentation/cgroups/cgroups.txt
@@ -299,11 +299,9 @@ a cgroup hierarchy's release_agent path is empty.
 1.5 What does clone_children do ?
 ---------------------------------
 
-If the clone_children flag is enabled (1) in a cgroup, then all
-cgroups created beneath will call the post_clone callbacks for each
-subsystem of the newly created cgroup. Usually when this callback is
-implemented for a subsystem, it copies the values of the parent
-subsystem, this is the case for the cpuset.
+This flag only affects the cpuset controller. If the clone_children
+flag is enabled (1) in a cgroup, a new cpuset cgroup will copy its
+configuration from the parent during initialization.
 
 1.6 How do I use cgroups ?
 --------------------------
@@ -553,16 +551,16 @@ call to cgroup_unload_subsys(). It should also set its_subsys.module =
 THIS_MODULE in its .c file.
 
 Each subsystem may export the following methods. The only mandatory
-methods are create/destroy. Any others that are null are presumed to
+methods are css_alloc/free. Any others that are null are presumed to
 be successful no-ops.
 
-struct cgroup_subsys_state *create(struct cgroup *cgrp)
+struct cgroup_subsys_state *css_alloc(struct cgroup *cgrp)
 (cgroup_mutex held by caller)
 
-Called to create a subsystem state object for a cgroup. The
+Called to allocate a subsystem state object for a cgroup. The
 subsystem should allocate its subsystem state object for the passed
 cgroup, returning a pointer to the new object on success or a
-negative error code. On success, the subsystem pointer should point to
+ERR_PTR() value. On success, the subsystem pointer should point to
 a structure of type cgroup_subsys_state (typically embedded in a
 larger subsystem-specific object), which will be initialized by the
 cgroup system. Note that this will be called at initialization to
@@ -571,24 +569,33 @@ identified by the passed cgroup object having a NULL parent (since
 it's the root of the hierarchy) and may be an appropriate place for
 initialization code.
 
-void destroy(struct cgroup *cgrp)
+int css_online(struct cgroup *cgrp)
 (cgroup_mutex held by caller)
 
-The cgroup system is about to destroy the passed cgroup; the subsystem
-should do any necessary cleanup and free its subsystem state
-object. By the time this method is called, the cgroup has already been
-unlinked from the file system and from the child list of its parent;
-cgroup->parent is still valid. (Note - can also be called for a
-newly-created cgroup if an error occurs after this subsystem's
-create() method has been called for the new cgroup).
+Called after @cgrp successfully completed all allocations and made
+visible to cgroup_for_each_child/descendant_*() iterators. The
+subsystem may choose to fail creation by returning -errno. This
+callback can be used to implement reliable state sharing and
+propagation along the hierarchy. See the comment on
+cgroup_for_each_descendant_pre() for details.
 
-int pre_destroy(struct cgroup *cgrp);
+void css_offline(struct cgroup *cgrp);
 
-Called before checking the reference count on each subsystem. This may
-be useful for subsystems which have some extra references even if
-there are not tasks in the cgroup. If pre_destroy() returns error code,
-rmdir() will fail with it. From this behavior, pre_destroy() can be
-called multiple times against a cgroup.
+This is the counterpart of css_online() and called iff css_online()
+has succeeded on @cgrp. This signifies the beginning of the end of
+@cgrp. @cgrp is being removed and the subsystem should start dropping
+all references it's holding on @cgrp. When all references are dropped,
+cgroup removal will proceed to the next step - css_free(). After this
+callback, @cgrp should be considered dead to the subsystem.
+
+void css_free(struct cgroup *cgrp)
+(cgroup_mutex held by caller)
+
+The cgroup system is about to free @cgrp; the subsystem should free
+its subsystem state object. By the time this method is called, @cgrp
+is completely unused; @cgrp->parent is still valid. (Note - can also
+be called for a newly-created cgroup if an error occurs after this
+subsystem's create() method has been called for the new cgroup).
 
 int can_attach(struct cgroup *cgrp, struct cgroup_taskset *tset)
 (cgroup_mutex held by caller)
@@ -635,14 +642,6 @@ void exit(struct task_struct *task)
 
 Called during task exit.
 
-void post_clone(struct cgroup *cgrp)
-(cgroup_mutex held by caller)
-
-Called during cgroup_create() to do any parameter
-initialization which might be required before a task could attach.  For
-example, in cpusets, no task may attach before 'cpus' and 'mems' are set
-up.
-
 void bind(struct cgroup *root)
 (cgroup_mutex held by caller)
 
diff --git a/Documentation/cgroups/freezer-subsystem.txt b/Documentation/cgroups/freezer-subsystem.txt
index 7e62de1e59ff..c96a72cbb30a 100644
--- a/Documentation/cgroups/freezer-subsystem.txt
+++ b/Documentation/cgroups/freezer-subsystem.txt
@@ -49,13 +49,49 @@ prevent the freeze/unfreeze cycle from becoming visible to the tasks
 being frozen. This allows the bash example above and gdb to run as
 expected.
 
-The freezer subsystem in the container filesystem defines a file named
-freezer.state. Writing "FROZEN" to the state file will freeze all tasks in the
-cgroup. Subsequently writing "THAWED" will unfreeze the tasks in the cgroup.
-Reading will return the current state.
+The cgroup freezer is hierarchical. Freezing a cgroup freezes all
+tasks beloning to the cgroup and all its descendant cgroups. Each
+cgroup has its own state (self-state) and the state inherited from the
+parent (parent-state). Iff both states are THAWED, the cgroup is
+THAWED.
 
-Note freezer.state doesn't exist in root cgroup, which means root cgroup
-is non-freezable.
+The following cgroupfs files are created by cgroup freezer.
+
+* freezer.state: Read-write.
+
+  When read, returns the effective state of the cgroup - "THAWED",
+  "FREEZING" or "FROZEN". This is the combined self and parent-states.
+  If any is freezing, the cgroup is freezing (FREEZING or FROZEN).
+
+  FREEZING cgroup transitions into FROZEN state when all tasks
+  belonging to the cgroup and its descendants become frozen. Note that
+  a cgroup reverts to FREEZING from FROZEN after a new task is added
+  to the cgroup or one of its descendant cgroups until the new task is
+  frozen.
+
+  When written, sets the self-state of the cgroup. Two values are
+  allowed - "FROZEN" and "THAWED". If FROZEN is written, the cgroup,
+  if not already freezing, enters FREEZING state along with all its
+  descendant cgroups.
+
+  If THAWED is written, the self-state of the cgroup is changed to
+  THAWED.  Note that the effective state may not change to THAWED if
+  the parent-state is still freezing. If a cgroup's effective state
+  becomes THAWED, all its descendants which are freezing because of
+  the cgroup also leave the freezing state.
+
+* freezer.self_freezing: Read only.
+
+  Shows the self-state. 0 if the self-state is THAWED; otherwise, 1.
+  This value is 1 iff the last write to freezer.state was "FROZEN".
+
+* freezer.parent_freezing: Read only.
+
+  Shows the parent-state.  0 if none of the cgroup's ancestors is
+  frozen; otherwise, 1.
+
+The root cgroup is non-freezable and the above interface files don't
+exist.
 
 * Examples of usage :
 
@@ -85,18 +121,3 @@ to unfreeze all tasks in the container :
 
 This is the basic mechanism which should do the right thing for user space task
 in a simple scenario.
-
-It's important to note that freezing can be incomplete. In that case we return
-EBUSY. This means that some tasks in the cgroup are busy doing something that
-prevents us from completely freezing the cgroup at this time. After EBUSY,
-the cgroup will remain partially frozen -- reflected by freezer.state reporting
-"FREEZING" when read. The state will remain "FREEZING" until one of these
-things happens:
-
-	1) Userspace cancels the freezing operation by writing "THAWED" to
-		the freezer.state file
-	2) Userspace retries the freezing operation by writing "FROZEN" to
-		the freezer.state file (writing "FREEZING" is not legal
-		and returns EINVAL)
-	3) The tasks that blocked the cgroup from entering the "FROZEN"
-		state disappear from the cgroup's set of tasks.
diff --git a/Documentation/cgroups/net_prio.txt b/Documentation/cgroups/net_prio.txt
index 01b322635591..a82cbd28ea8a 100644
--- a/Documentation/cgroups/net_prio.txt
+++ b/Documentation/cgroups/net_prio.txt
@@ -51,3 +51,5 @@ One usage for the net_prio cgroup is with mqprio qdisc allowing application
 traffic to be steered to hardware/driver based traffic classes. These mappings
 can then be managed by administrators or other networking protocols such as
 DCBX.
+
+A new net_prio cgroup inherits the parent's configuration.