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authorTejun Heo <tj@kernel.org>2014-05-16 21:22:48 +0400
committerTejun Heo <tj@kernel.org>2014-05-16 21:22:48 +0400
commit5c9d535b893f30266ea29fe377cb9b002fcd76aa (patch)
tree27b1fd6e16c5b0c0729a93c4924289119033137c /include/linux/cgroup.h
parent3b514d24e200fcdcde0a57c354a51d3677a86743 (diff)
downloadlinux-5c9d535b893f30266ea29fe377cb9b002fcd76aa.tar.xz
cgroup: remove css_parent()
cgroup in general is moving towards using cgroup_subsys_state as the fundamental structural component and css_parent() was introduced to convert from using cgroup->parent to css->parent. It was quite some time ago and we're moving forward with making css more prominent. This patch drops the trivial wrapper css_parent() and let the users dereference css->parent. While at it, explicitly mark fields of css which are public and immutable. v2: New usage from device_cgroup.c converted. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Michal Hocko <mhocko@suse.cz> Acked-by: Neil Horman <nhorman@tuxdriver.com> Acked-by: "David S. Miller" <davem@davemloft.net> Acked-by: Li Zefan <lizefan@huawei.com> Cc: Vivek Goyal <vgoyal@redhat.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Johannes Weiner <hannes@cmpxchg.org>
Diffstat (limited to 'include/linux/cgroup.h')
-rw-r--r--include/linux/cgroup.h29
1 files changed, 11 insertions, 18 deletions
diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
index 1737db0c63fe..2549493d518d 100644
--- a/include/linux/cgroup.h
+++ b/include/linux/cgroup.h
@@ -48,22 +48,28 @@ enum cgroup_subsys_id {
};
#undef SUBSYS
-/* Per-subsystem/per-cgroup state maintained by the system. */
+/*
+ * Per-subsystem/per-cgroup state maintained by the system. This is the
+ * fundamental structural building block that controllers deal with.
+ *
+ * Fields marked with "PI:" are public and immutable and may be accessed
+ * directly without synchronization.
+ */
struct cgroup_subsys_state {
- /* the cgroup that this css is attached to */
+ /* PI: the cgroup that this css is attached to */
struct cgroup *cgroup;
- /* the cgroup subsystem that this css is attached to */
+ /* PI: the cgroup subsystem that this css is attached to */
struct cgroup_subsys *ss;
/* reference count - access via css_[try]get() and css_put() */
struct percpu_ref refcnt;
- /* the parent css */
+ /* PI: the parent css */
struct cgroup_subsys_state *parent;
/*
- * Subsys-unique ID. 0 is unused and root is always 1. The
+ * PI: Subsys-unique ID. 0 is unused and root is always 1. The
* matching css can be looked up using css_from_id().
*/
int id;
@@ -670,19 +676,6 @@ struct cgroup_subsys {
#undef SUBSYS
/**
- * css_parent - find the parent css
- * @css: the target cgroup_subsys_state
- *
- * Return the parent css of @css. This function is guaranteed to return
- * non-NULL parent as long as @css isn't the root.
- */
-static inline
-struct cgroup_subsys_state *css_parent(struct cgroup_subsys_state *css)
-{
- return css->parent;
-}
-
-/**
* task_css_set_check - obtain a task's css_set with extra access conditions
* @task: the task to obtain css_set for
* @__c: extra condition expression to be passed to rcu_dereference_check()