Commit be445626 authored by Li Zefan's avatar Li Zefan Committed by Tejun Heo
Browse files

cgroup: remove synchronize_rcu() from cgroup_diput() 



Free cgroup via call_rcu(). The actual work is done through
workqueue.

Signed-off-by: default avatarLi Zefan <lizefan@huawei.com>
Signed-off-by: default avatarTejun Heo <tj@kernel.org>
parent 86a3db56

include/linux/cgroup.h

+1 −0
Original line number Diff line number Diff line
@@ -203,6 +203,7 @@ struct cgroup { 


	/* For RCU-protected deletion */

	struct rcu_head rcu_head;

	struct work_struct free_work;



	/* List of events which userspace want to receive */

	struct list_head event_list;

kernel/cgroup.c

+43 −29
Original line number Diff line number Diff line
@@ -852,20 +852,10 @@ static struct inode *cgroup_new_inode(umode_t mode, struct super_block *sb) 
	return inode;

}



static void cgroup_diput(struct dentry *dentry, struct inode *inode)

static void cgroup_free_fn(struct work_struct *work)

{

	/* is dentry a directory ? if so, kfree() associated cgroup */

	if (S_ISDIR(inode->i_mode)) {

		struct cgroup *cgrp = dentry->d_fsdata;

	struct cgroup *cgrp = container_of(work, struct cgroup, free_work);

	struct cgroup_subsys *ss;

		BUG_ON(!(cgroup_is_removed(cgrp)));

		/* It's possible for external users to be holding css

		 * reference counts on a cgroup; css_put() needs to

		 * be able to access the cgroup after decrementing

		 * the reference count in order to know if it needs to

		 * queue the cgroup to be handled by the release

		 * agent */

		synchronize_rcu();



	mutex_lock(&cgroup_mutex);

	/*
@@ -893,6 +883,29 @@ static void cgroup_diput(struct dentry *dentry, struct inode *inode) 


	ida_simple_remove(&cgrp->root->cgroup_ida, cgrp->id);

	kfree(cgrp);

}



static void cgroup_free_rcu(struct rcu_head *head)

{

	struct cgroup *cgrp = container_of(head, struct cgroup, rcu_head);



	schedule_work(&cgrp->free_work);

}



static void cgroup_diput(struct dentry *dentry, struct inode *inode)

{

	/* is dentry a directory ? if so, kfree() associated cgroup */

	if (S_ISDIR(inode->i_mode)) {

		struct cgroup *cgrp = dentry->d_fsdata;



		BUG_ON(!(cgroup_is_removed(cgrp)));

		/* It's possible for external users to be holding css

		 * reference counts on a cgroup; css_put() needs to

		 * be able to access the cgroup after decrementing

		 * the reference count in order to know if it needs to

		 * queue the cgroup to be handled by the release

		 * agent */

		call_rcu(&cgrp->rcu_head, cgroup_free_rcu);

	} else {

		struct cfent *cfe = __d_cfe(dentry);

		struct cgroup *cgrp = dentry->d_parent->d_fsdata;
@@ -1391,6 +1404,7 @@ static void init_cgroup_housekeeping(struct cgroup *cgrp) 
	INIT_LIST_HEAD(&cgrp->allcg_node);

	INIT_LIST_HEAD(&cgrp->release_list);

	INIT_LIST_HEAD(&cgrp->pidlists);

	INIT_WORK(&cgrp->free_work, cgroup_free_fn);

	mutex_init(&cgrp->pidlist_mutex);

	INIT_LIST_HEAD(&cgrp->event_list);

	spin_lock_init(&cgrp->event_list_lock);