diff options
Diffstat (limited to 'kernel/cgroup.c')
| -rw-r--r-- | kernel/cgroup.c | 25 |
1 files changed, 16 insertions, 9 deletions
diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 2de8decfd99f..fc2db071d95e 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -4978,28 +4978,35 @@ static int __init cgroup_disable(char *str) __setup("cgroup_disable=", cgroup_disable); /** - * css_from_dir - get corresponding css from the dentry of a cgroup dir + * css_tryget_from_dir - get corresponding css from the dentry of a cgroup dir * @dentry: directory dentry of interest * @ss: subsystem of interest * - * Must be called under cgroup_mutex or RCU read lock. The caller is - * responsible for pinning the returned css if it needs to be accessed - * outside the critical section. + * If @dentry is a directory for a cgroup which has @ss enabled on it, try + * to get the corresponding css and return it. If such css doesn't exist + * or can't be pinned, an ERR_PTR value is returned. */ -struct cgroup_subsys_state *css_from_dir(struct dentry *dentry, - struct cgroup_subsys *ss) +struct cgroup_subsys_state *css_tryget_from_dir(struct dentry *dentry, + struct cgroup_subsys *ss) { struct cgroup *cgrp; - - cgroup_assert_mutex_or_rcu_locked(); + struct cgroup_subsys_state *css; /* is @dentry a cgroup dir? */ if (!dentry->d_inode || dentry->d_inode->i_op != &cgroup_dir_inode_operations) return ERR_PTR(-EBADF); + rcu_read_lock(); + cgrp = __d_cgrp(dentry); - return cgroup_css(cgrp, ss) ?: ERR_PTR(-ENOENT); + css = cgroup_css(cgrp, ss); + + if (!css || !css_tryget(css)) + css = ERR_PTR(-ENOENT); + + rcu_read_unlock(); + return css; } /** |