cgroup: add __rcu modifier to cgroup->subsys[]
For the planned unified hierarchy, each css (cgroup_subsys_state) will
be RCU protected so that it can be created and destroyed individually
while allowing RCU accesses. Previous changes ensured that all
cgroup->subsys[] accesses use the cgroup_css() accessor. This patch
adds __rcu modifier to cgroup->subsys[], add matching RCU dereference
in cgroup_css() and convert all assignments to either
rcu_assign_pointer() or RCU_INIT_POINTER().
This change prepares for the actual RCUfication of css's and doesn't
introduce any visible behavior change. The conversion is verified
with sparse and all accesses are properly RCU annotated.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
index 8a5dc91..eb200b5 100644
--- a/include/linux/cgroup.h
+++ b/include/linux/cgroup.h
@@ -204,7 +204,7 @@
struct cgroup_name __rcu *name;
/* Private pointers for each registered subsystem */
- struct cgroup_subsys_state *subsys[CGROUP_SUBSYS_COUNT];
+ struct cgroup_subsys_state __rcu *subsys[CGROUP_SUBSYS_COUNT];
struct cgroupfs_root *root;