From eb6fd5040ee799009173daa49c3e7aa0362167c9 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Fri, 9 Nov 2012 09:12:29 -0800 Subject: [PATCH] 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 Reviewed-by: Michal Hocko Reviewed-by: KAMEZAWA Hiroyuki Acked-by: Li Zefan --- include/linux/cgroup.h | 1 + kernel/cgroup.c | 8 +++----- 2 files changed, 4 insertions(+), 5 deletions(-) diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h index b4421221111d..90c33ebdd6bc 100644 --- a/include/linux/cgroup.h +++ b/include/linux/cgroup.h @@ -12,6 +12,7 @@ #include #include #include +#include #include #include #include diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 26f2edbaf4f5..2ed5968a04e7 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -1650,7 +1650,6 @@ static struct dentry *cgroup_mount(struct file_system_type *fs_type, 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 @@ static void cgroup_kill_sb(struct super_block *sb) { 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 @@ static long cgroup_create(struct cgroup *parent, struct dentry *dentry, } } - 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 @@ static long cgroup_create(struct cgroup *parent, struct dentry *dentry, err_remove: - list_del(&cgrp->sibling); + list_del_rcu(&cgrp->sibling); root->number_of_cgroups--; err_destroy: @@ -4209,7 +4207,7 @@ static int cgroup_rmdir(struct inode *unused_dir, struct dentry *dentry) 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); -- 2.20.1