From be44562613851235d801d41d5b3976dc4333f622 Mon Sep 17 00:00:00 2001 From: Li Zefan Date: Thu, 24 Jan 2013 14:31:42 +0800 Subject: [PATCH] cgroup: remove synchronize_rcu() from cgroup_diput() Free cgroup via call_rcu(). The actual work is done through workqueue. Signed-off-by: Li Zefan Signed-off-by: Tejun Heo --- include/linux/cgroup.h | 1 + kernel/cgroup.c | 72 +++++++++++++++++++++++++----------------- 2 files changed, 44 insertions(+), 29 deletions(-) diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h index 8118a3120378..900af5964f55 100644 --- a/include/linux/cgroup.h +++ b/include/linux/cgroup.h @@ -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; diff --git a/kernel/cgroup.c b/kernel/cgroup.c index af993919aa04..02e4f201472e 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -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); -- 2.20.1