cgroup: use rculist ops for cgroup->children
Use RCU safe list operations for cgroup->children. This will be used
to implement cgroup children / descendant walking which can be used by
controllers.
Note that cgroup_create() now puts a new cgroup at the end of the
->children list instead of head. This isn't strictly necessary but is
done so that the iteration order is more conventional.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Michal Hocko <mhocko@suse.cz>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: Li Zefan <lizefan@huawei.com>
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 26f2edb..2ed5968 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -1650,7 +1650,6 @@
free_cg_links(&tmp_cg_links);
- BUG_ON(!list_empty(&root_cgrp->sibling));
BUG_ON(!list_empty(&root_cgrp->children));
BUG_ON(root->number_of_cgroups != 1);
@@ -1699,7 +1698,6 @@
BUG_ON(root->number_of_cgroups != 1);
BUG_ON(!list_empty(&cgrp->children));
- BUG_ON(!list_empty(&cgrp->sibling));
mutex_lock(&cgroup_mutex);
mutex_lock(&cgroup_root_mutex);
@@ -4052,7 +4050,7 @@
}
}
- list_add(&cgrp->sibling, &cgrp->parent->children);
+ list_add_tail_rcu(&cgrp->sibling, &cgrp->parent->children);
root->number_of_cgroups++;
err = cgroup_create_dir(cgrp, dentry, mode);
@@ -4083,7 +4081,7 @@
err_remove:
- list_del(&cgrp->sibling);
+ list_del_rcu(&cgrp->sibling);
root->number_of_cgroups--;
err_destroy:
@@ -4209,7 +4207,7 @@
raw_spin_unlock(&release_list_lock);
/* delete this cgroup from parent->children */
- list_del_init(&cgrp->sibling);
+ list_del_rcu(&cgrp->sibling);
list_del_init(&cgrp->allcg_node);