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| author | Tejun Heo <tj@kernel.org> | 2013-08-08 20:11:24 -0400 |
|---|---|---|
| committer | Tejun Heo <tj@kernel.org> | 2013-08-08 20:11:24 -0400 |
| commit | 67f4c36f83455b253445b2cb28ac9a2c4f85d99a (patch) | |
| tree | 3c7aecc6fc830799cf36716ea64583cc10cb9d40 /include/linux/cgroup.h | |
| parent | f7d58818ba4249f04a83b73aaac135640050bb4f (diff) | |
| download | lwn-67f4c36f83455b253445b2cb28ac9a2c4f85d99a.tar.gz lwn-67f4c36f83455b253445b2cb28ac9a2c4f85d99a.zip | |
cgroup: add cgroup->dummy_css
cgroup subsystem API is being converted to use css
(cgroup_subsys_state) as the main handle, which makes things a bit
awkward for subsystem agnostic core features - the "cgroup.*"
interface files and various iterations - a bit awkward as they don't
have a css to use.
This patch adds cgroup->dummy_css which has NULL ->ss and whose only
role is pointing back to the cgroup. This will be used to support
subsystem agnostic features on the coming css based API.
css_parent() is updated to handle dummy_css's. Note that css will
soon grow its own ->parent field and css_parent() will be made
trivial.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
Diffstat (limited to 'include/linux/cgroup.h')
| -rw-r--r-- | include/linux/cgroup.h | 11 |
1 files changed, 10 insertions, 1 deletions
diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h index 5db8138a0482..b0d5f53ae5e1 100644 --- a/include/linux/cgroup.h +++ b/include/linux/cgroup.h @@ -225,6 +225,9 @@ struct cgroup { struct list_head pidlists; struct mutex pidlist_mutex; + /* dummy css with NULL ->ss, points back to this cgroup */ + struct cgroup_subsys_state dummy_css; + /* For css percpu_ref killing and RCU-protected deletion */ struct rcu_head rcu_head; struct work_struct destroy_work; @@ -668,7 +671,13 @@ struct cgroup_subsys_state *css_parent(struct cgroup_subsys_state *css) { struct cgroup *parent_cgrp = css->cgroup->parent; - return parent_cgrp ? parent_cgrp->subsys[css->ss->subsys_id] : NULL; + if (!parent_cgrp) + return NULL; + + if (css->ss) + return parent_cgrp->subsys[css->ss->subsys_id]; + else + return &parent_cgrp->dummy_css; } /** |