cgroup: reorganize css_task_iter
This patch reorganizes css_task_iter so that adding effective css
support is easier.
* s/->cset_link/->cset_pos/ and s/->task/->task_pos/ for consistency
* ->origin_css is used to determine whether the iteration reached the
last css_set. Replace it with explicit ->cset_head so that
css_advance_task_iter() doesn't have to know the termination
condition directly.
* css_task_iter_next() currently assumes that it's walking list of
cgrp_cset_link and reaches into the current cset through the current
link to determine the termination conditions for task walking. As
this won't always be true for effective css walking, add
->tasks_head and ->mg_tasks_head and use them to control task
walking so that css_task_iter_next() doesn't have to know how
css_sets are being walked.
This patch doesn't make any behavior changes. The iteration logic
stays unchanged after the patch.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
index 33a0043..bee3905 100644
--- a/include/linux/cgroup.h
+++ b/include/linux/cgroup.h
@@ -842,9 +842,12 @@
/* A css_task_iter should be treated as an opaque object */
struct css_task_iter {
- struct cgroup_subsys_state *origin_css;
- struct list_head *cset_link;
- struct list_head *task;
+ struct list_head *cset_pos;
+ struct list_head *cset_head;
+
+ struct list_head *task_pos;
+ struct list_head *tasks_head;
+ struct list_head *mg_tasks_head;
};
void css_task_iter_start(struct cgroup_subsys_state *css,