cgroup: make task iterators deal with cgroup_subsys_state instead of cgroup

cgroup is in the process of converting to css (cgroup_subsys_state)
from cgroup as the principal subsystem interface handle.  This is
mostly to prepare for the unified hierarchy support where css's will
be created and destroyed dynamically but also helps cleaning up
subsystem implementations as css is usually what they are interested
in anyway.

This patch converts task iterators to deal with css instead of cgroup.
Note that under unified hierarchy, different sets of tasks will be
considered belonging to a given cgroup depending on the subsystem in
question and making the iterators deal with css instead cgroup
provides them with enough information about the iteration.

While at it, fix several function comment formats in cpuset.c.

This patch doesn't introduce any behavior differences.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: Matt Helsley <matthltc@us.ibm.com>

1 files changed, 11 insertions, 10 deletions

diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
index 8472ed576b64..cd105fce089c 100644
--- a/include/linux/cgroup.h
+++ b/include/linux/cgroup.h
@@ -880,21 +880,22 @@ css_next_descendant_post(struct cgroup_subsys_state *pos,
         for ((pos) = css_next_descendant_post(NULL, (css)); (pos);      \
              (pos) = css_next_descendant_post((pos), (css)))
 
-/* A cgroup_task_iter should be treated as an opaque object */
-struct cgroup_task_iter {
-        struct cgroup                   *origin_cgrp;
+/* 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;
 };
 
-void cgroup_task_iter_start(struct cgroup *cgrp, struct cgroup_task_iter *it);
-struct task_struct *cgroup_task_iter_next(struct cgroup_task_iter *it);
-void cgroup_task_iter_end(struct cgroup_task_iter *it);
+void css_task_iter_start(struct cgroup_subsys_state *css,
+                         struct css_task_iter *it);
+struct task_struct *css_task_iter_next(struct css_task_iter *it);
+void css_task_iter_end(struct css_task_iter *it);
 
-int cgroup_scan_tasks(struct cgroup *cgrp,
-                      bool (*test)(struct task_struct *, void *),
-                      void (*process)(struct task_struct *, void *),
-                      void *data, struct ptr_heap *heap);
+int css_scan_tasks(struct cgroup_subsys_state *css,
+                   bool (*test)(struct task_struct *, void *),
+                   void (*process)(struct task_struct *, void *),
+                   void *data, struct ptr_heap *heap);
 
 int cgroup_attach_task_all(struct task_struct *from, struct task_struct *);
 int cgroup_transfer_tasks(struct cgroup *to, struct cgroup *from);