diff options
| author | Tejun Heo <tj@kernel.org> | 2013-08-08 20:11:23 -0400 |
|---|---|---|
| committer | Tejun Heo <tj@kernel.org> | 2013-08-08 20:11:23 -0400 |
| commit | 6387698699afd72d6304566fb6ccf84bffe07c56 (patch) | |
| tree | 9440e96fa8e5adce62409a5b0e40984dfedaada3 /block | |
| parent | a7c6d554aa01236ac2a9f851ab0f75704f76dfa2 (diff) | |
cgroup: add css_parent()
Currently, controllers have to explicitly follow the cgroup hierarchy
to find the parent of a given css. cgroup is moving towards using
cgroup_subsys_state as the main controller interface construct, so
let's provide a way to climb the hierarchy using just csses.
This patch implements css_parent() which, given a css, returns its
parent. The function is guarnateed to valid non-NULL parent css as
long as the target css is not at the top of the hierarchy.
freezer, cpuset, cpu, cpuacct, hugetlb, memory, net_cls and devices
are converted to use css_parent() instead of accessing cgroup->parent
directly.
* __parent_ca() is dropped from cpuacct and its usage is replaced with
parent_ca(). The only difference between the two was NULL test on
cgroup->parent which is now embedded in css_parent() making the
distinction moot. Note that eventually a css->parent field will be
added to css and the NULL check in css_parent() will go away.
This patch shouldn't cause any behavior differences.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
Diffstat (limited to 'block')
| -rw-r--r-- | block/blk-cgroup.h | 4 |
1 files changed, 1 insertions, 3 deletions
diff --git a/block/blk-cgroup.h b/block/blk-cgroup.h index 8e5863e900b..b6802c46d68 100644 --- a/block/blk-cgroup.h +++ b/block/blk-cgroup.h @@ -209,9 +209,7 @@ static inline struct blkcg *bio_blkcg(struct bio *bio) */ static inline struct blkcg *blkcg_parent(struct blkcg *blkcg) { - struct cgroup *pcg = blkcg->css.cgroup->parent; - - return pcg ? cgroup_to_blkcg(pcg) : NULL; + return css_to_blkcg(css_parent(&blkcg->css)); } /** |