diff options
Diffstat (limited to 'kernel/cgroup.c')
| -rw-r--r-- | kernel/cgroup.c | 12 |
1 files changed, 10 insertions, 2 deletions
diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 5c6dd7ed26a7..cbb6314f1836 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -5616,8 +5616,14 @@ struct cgroup_subsys_state *css_lookup(struct cgroup_subsys *ss, int id) } EXPORT_SYMBOL_GPL(css_lookup); -/* - * get corresponding css from file open on cgroupfs directory +/** + * cgroup_css_from_dir - get corresponding css from file open on cgroup dir + * @f: directory file of interest + * @id: subsystem id of interest + * + * Must be called under RCU read lock. The caller is responsible for + * pinning the returned css if it needs to be accessed outside the RCU + * critical section. */ struct cgroup_subsys_state *cgroup_css_from_dir(struct file *f, int id) { @@ -5625,6 +5631,8 @@ struct cgroup_subsys_state *cgroup_css_from_dir(struct file *f, int id) struct inode *inode; struct cgroup_subsys_state *css; + WARN_ON_ONCE(!rcu_read_lock_held()); + inode = file_inode(f); /* check in cgroup filesystem dir */ if (inode->i_op != &cgroup_dir_inode_operations) |