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cgroup: implement cgroup->e_csets[]

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On the default unified hierarchy, a cgroup may be associated with
csses of its ancestors, which means that a css of a given cgroup may
be associated with css_sets of descendant cgroups.  This means that we
can't walk all tasks associated with a css by iterating the css_sets
associated with the cgroup as there are css_sets which are pointing to
the css but linked on the descendants.

This patch adds per-subsystem list heads cgroup->e_csets[].  Any
css_set which is pointing to a css is linked to
css->cgroup->e_csets[$SUBSYS_ID] through
css_set->e_cset_node[$SUBSYS_ID].  The lists are protected by
css_set_rwsem and will allow us to walk all css_sets associated with a
given css so that we can find out all associated tasks.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
This commit is contained in:
Tejun Heo 2014-04-23 11:13:15 -04:00
parent aec3dfcb2e
commit 2d8f243a5e
2 changed files with 46 additions and 2 deletions
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18
include/linux/cgroup.h
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@ -187,6 +187,15 @@ struct cgroup {
*/
struct list_head cset_links;
/*
* On the default hierarchy, a css_set for a cgroup with some
* susbsys disabled will point to css's which are associated with
* the closest ancestor which has the subsys enabled. The
* following lists all css_sets which point to this cgroup's css
* for the given subsystem.
*/
struct list_head e_csets[CGROUP_SUBSYS_COUNT];
/*
* Linked list running through all cgroups that can
* potentially be reaped by the release agent. Protected by
@ -369,6 +378,15 @@ struct css_set {
struct cgroup *mg_src_cgrp;
struct css_set *mg_dst_cset;
/*
* On the default hierarhcy, ->subsys[ssid] may point to a css
* attached to an ancestor instead of the cgroup this css_set is
* associated with. The following node is anchored at
* ->subsys[ssid]->cgroup->e_csets[ssid] and provides a way to
* iterate through all css's attached to a given cgroup.
*/
struct list_head e_cset_node[CGROUP_SUBSYS_COUNT];
/* For RCU-protected deletion */
struct rcu_head rcu_head;
};