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authorTejun Heo <tj@kernel.org>2013-08-08 20:11:23 -0400
committerTejun Heo <tj@kernel.org>2013-08-08 20:11:23 -0400
commit6387698699afd72d6304566fb6ccf84bffe07c56 (patch)
tree9440e96fa8e5adce62409a5b0e40984dfedaada3 /net/sched/cls_cgroup.c
parentcgroup: add/update accessors which obtain subsys specific data from css (diff)
downloadlinux-dev-6387698699afd72d6304566fb6ccf84bffe07c56.tar.xz
linux-dev-6387698699afd72d6304566fb6ccf84bffe07c56.zip
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 'net/sched/cls_cgroup.c')
-rw-r--r--net/sched/cls_cgroup.c8
1 files changed, 5 insertions, 3 deletions
diff --git a/net/sched/cls_cgroup.c b/net/sched/cls_cgroup.c
index af412ab2b477..9e6b75e5efce 100644
--- a/net/sched/cls_cgroup.c
+++ b/net/sched/cls_cgroup.c
@@ -50,9 +50,11 @@ static struct cgroup_subsys_state *cgrp_css_alloc(struct cgroup *cgrp)
static int cgrp_css_online(struct cgroup *cgrp)
{
- if (cgrp->parent)
- cgrp_cls_state(cgrp)->classid =
- cgrp_cls_state(cgrp->parent)->classid;
+ struct cgroup_cls_state *cs = cgrp_cls_state(cgrp);
+ struct cgroup_cls_state *parent = css_cls_state(css_parent(&cs->css));
+
+ if (parent)
+ cs->classid = parent->classid;
return 0;
}