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cgroup: remove synchronize_rcu() from cgroup_diput() 

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

Signed-off-by: Li Zefan <lizefan@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
This commit is contained in:
Li Zefan 2013-01-24 14:31:42 +08:00 committed by Tejun Heo
parent 86a3db5643
commit be44562613
2 changed files with 44 additions and 29 deletions
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1
include/linux/cgroup.h
View File

@ -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;

72
kernel/cgroup.c
View File

@ -852,12 +852,52 @@ static struct inode *cgroup_new_inode(umode_t mode, struct super_block *sb)
return inode;
}
static void cgroup_free_fn(struct work_struct *work)
{
struct cgroup *cgrp = container_of(work, struct cgroup, free_work);
struct cgroup_subsys *ss;
mutex_lock(&cgroup_mutex);
/*
* Release the subsystem state objects.
*/
for_each_subsys(cgrp->root, ss)
ss->css_free(cgrp);
cgrp->root->number_of_cgroups--;
mutex_unlock(&cgroup_mutex);
/*
* Drop the active superblock reference that we took when we
* created the cgroup
*/
deactivate_super(cgrp->root->sb);
/*
* if we're getting rid of the cgroup, refcount should ensure
* that there are no pidlists left.
*/
BUG_ON(!list_empty(&cgrp->pidlists));
simple_xattrs_free(&cgrp->xattrs);
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;
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
@ -865,34 +905,7 @@ static void cgroup_diput(struct dentry *dentry, struct inode *inode)
* 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);
/*
* Release the subsystem state objects.
*/
for_each_subsys(cgrp->root, ss)
ss->css_free(cgrp);
cgrp->root->number_of_cgroups--;
mutex_unlock(&cgroup_mutex);
/*
* Drop the active superblock reference that we took when we
* created the cgroup
*/
deactivate_super(cgrp->root->sb);
/*
* if we're getting rid of the cgroup, refcount should ensure
* that there are no pidlists left.
*/
BUG_ON(!list_empty(&cgrp->pidlists));
simple_xattrs_free(&cgrp->xattrs);
ida_simple_remove(&cgrp->root->cgroup_ida, cgrp->id);
kfree(cgrp);
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);