cgroups: let ss->can_attach and ss->attach do whole threadgroups at a time

[safe/jmp/linux-2.6] / Documentation / cgroups / cgroups.txt

diff --git a/Documentation/cgroups/cgroups.txt b/Documentation/cgroups/cgroups.txt
index 4bccfc1..455d4e6 100644 (file)
--- a/Documentation/cgroups/cgroups.txt
+++ b/Documentation/cgroups/cgroups.txt
@@ -521,7 +521,7 @@ rmdir() will fail with it. From this behavior, pre_destroy() can be
 called multiple times against a cgroup.
 
 int can_attach(struct cgroup_subsys *ss, struct cgroup *cgrp,
-              struct task_struct *task)
+              struct task_struct *task, bool threadgroup)
 (cgroup_mutex held by caller)
 
 Called prior to moving a task into a cgroup; if the subsystem
@@ -529,14 +529,20 @@ returns an error, this will abort the attach operation.  If a NULL
 task is passed, then a successful result indicates that *any*
 unspecified task can be moved into the cgroup. Note that this isn't
 called on a fork. If this method returns 0 (success) then this should
-remain valid while the caller holds cgroup_mutex.
+remain valid while the caller holds cgroup_mutex. If threadgroup is
+true, then a successful result indicates that all threads in the given
+thread's threadgroup can be moved together.
 
 void attach(struct cgroup_subsys *ss, struct cgroup *cgrp,
-           struct cgroup *old_cgrp, struct task_struct *task)
+           struct cgroup *old_cgrp, struct task_struct *task,
+           bool threadgroup)
 (cgroup_mutex held by caller)
 
 Called after the task has been attached to the cgroup, to allow any
 post-attachment activity that requires memory allocations or blocking.
+If threadgroup is true, the subsystem should take care of all threads
+in the specified thread's threadgroup. Currently does not support any
+subsystem that might need the old_cgrp for every thread in the group.
 
 void fork(struct cgroup_subsy *ss, struct task_struct *task)