From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tejun Heo Subject: [PATCH 11/17] cgroup: separate out cgroup_destroy_locked() Date: Mon, 12 Nov 2012 19:01:38 -0800 Message-ID: <1352775704-9023-12-git-send-email-tj@kernel.org> References: <1352775704-9023-1-git-send-email-tj@kernel.org> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1352775704-9023-1-git-send-email-tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: containers-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org Errors-To: containers-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org To: lizefan-hv44wF8Li93QT0dZR+AlfA@public.gmane.org, containers-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org, cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org Cc: mhocko-AlSwsSmVLrQ@public.gmane.org, Tejun Heo List-Id: containers.vger.kernel.org Separate out cgroup_destroy_locked() from cgroup_destroy(). This will be later used in cgroup_create() failure path. While at it, add lockdep asserts on i_mutex and cgroup_mutex, and move @d and @parent assignments to their declarations. This patch doesn't introduce any functional difference. Signed-off-by: Tejun Heo --- kernel/cgroup.c | 40 +++++++++++++++++++++++++--------------- 1 file changed, 25 insertions(+), 15 deletions(-) diff --git a/kernel/cgroup.c b/kernel/cgroup.c index c5368c0..afc47d6 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -242,6 +242,8 @@ static DEFINE_SPINLOCK(hierarchy_id_lock); */ static int need_forkexit_callback __read_mostly; +static int cgroup_destroy_locked(struct cgroup *cgrp); + #ifdef CONFIG_PROVE_LOCKING int cgroup_lock_is_held(void) { @@ -4209,22 +4211,20 @@ static int cgroup_has_css_refs(struct cgroup *cgrp) return 0; } -static int cgroup_rmdir(struct inode *unused_dir, struct dentry *dentry) +static int cgroup_destroy_locked(struct cgroup *cgrp) + __releases(&cgroup_mutex) __acquires(&cgroup_mutex) { - struct cgroup *cgrp = dentry->d_fsdata; - struct dentry *d; - struct cgroup *parent; + struct dentry *d = cgrp->dentry; + struct cgroup *parent = cgrp->parent; DEFINE_WAIT(wait); struct cgroup_event *event, *tmp; struct cgroup_subsys *ss; - /* the vfs holds both inode->i_mutex already */ - mutex_lock(&cgroup_mutex); - parent = cgrp->parent; - if (atomic_read(&cgrp->count) || !list_empty(&cgrp->children)) { - mutex_unlock(&cgroup_mutex); + lockdep_assert_held(&d->d_inode->i_mutex); + lockdep_assert_held(&cgroup_mutex); + + if (atomic_read(&cgrp->count) || !list_empty(&cgrp->children)) return -EBUSY; - } /* * Block new css_tryget() by deactivating refcnt and mark @cgrp @@ -4243,7 +4243,9 @@ static int cgroup_rmdir(struct inode *unused_dir, struct dentry *dentry) /* * Tell subsystems to initate destruction. pre_destroy() should be * called with cgroup_mutex unlocked. See 3fa59dfbc3 ("cgroup: fix - * potential deadlock in pre_destroy") for details. + * potential deadlock in pre_destroy") for details. This temporary + * unlocking should go away once cgroup_mutex is unexported from + * controllers. */ mutex_unlock(&cgroup_mutex); for_each_subsys(cgrp->root, ss) @@ -4268,11 +4270,9 @@ static int cgroup_rmdir(struct inode *unused_dir, struct dentry *dentry) /* delete this cgroup from parent->children */ list_del_rcu(&cgrp->sibling); - list_del_init(&cgrp->allcg_node); - d = dget(cgrp->dentry); - + dget(d); cgroup_d_remove_dir(d); dput(d); @@ -4293,10 +4293,20 @@ static int cgroup_rmdir(struct inode *unused_dir, struct dentry *dentry) } spin_unlock(&cgrp->event_list_lock); - mutex_unlock(&cgroup_mutex); return 0; } +static int cgroup_rmdir(struct inode *unused_dir, struct dentry *dentry) +{ + int ret; + + mutex_lock(&cgroup_mutex); + ret = cgroup_destroy_locked(dentry->d_fsdata); + mutex_unlock(&cgroup_mutex); + + return ret; +} + static void __init_or_module cgroup_init_cftsets(struct cgroup_subsys *ss) { INIT_LIST_HEAD(&ss->cftsets); -- 1.7.11.7