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Commit eb6fd504 authored by Tejun Heo's avatar Tejun Heo
Browse files

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: default avatarTejun Heo <tj@kernel.org>
Reviewed-by: default avatarMichal Hocko <mhocko@suse.cz>
Reviewed-by: default avatarKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: default avatarLi Zefan <lizefan@huawei.com>
parent a8638030

include/linux/cgroup.h

+1 −0
Original line number Diff line number Diff line
@@ -12,6 +12,7 @@ 
#include <linux/cpumask.h>

#include <linux/nodemask.h>

#include <linux/rcupdate.h>

#include <linux/rculist.h>

#include <linux/cgroupstats.h>

#include <linux/prio_heap.h>

#include <linux/rwsem.h>

kernel/cgroup.c

+3 −5
Original line number Diff line number Diff line
@@ -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);