diff options
| author | Tejun Heo <tj@kernel.org> | 2013-08-13 11:01:54 -0400 |
|---|---|---|
| committer | Tejun Heo <tj@kernel.org> | 2013-08-13 11:01:54 -0400 |
| commit | b77d7b6088377998ebf65eaea5e51008c2d75e94 (patch) | |
| tree | cab54dcd2c0639b127eb7920f6459d5f84695da0 /kernel/cgroup.c | |
| parent | 0ae78e0bf10ac38ab53548e18383afc9997eca22 (diff) | |
cgroup: cgroup_css_from_dir() now should be called with RCU read locked
cgroup->subsys[] will become RCU protected and thus all cgroup_css()
usages should either be under RCU read lock or cgroup_mutex. This
patch updates cgroup_css_from_dir() which returns the matching
cgroup_subsys_state given a directory file and subsys_id so that it
requires RCU read lock and updates its sole user
perf_cgroup_connect().
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@redhat.com>
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) |