cgroup: change cgroup_from_id() to css_from_id()
Now we want cgroup core to always provide the css to use to the
subsystems, so change this API to css_from_id().
Uninline css_from_id(), because it's getting bigger and cgroup_css()
has been unexported.
While at it, remove the #ifdef, and shuffle the order of the args.
Signed-off-by: Li Zefan <lizefan@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index b69b572..ff7d642 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -5717,6 +5717,28 @@
return css ? css : ERR_PTR(-ENOENT);
}
+/**
+ * css_from_id - lookup css by id
+ * @id: the cgroup id
+ * @ss: cgroup subsys to be looked into
+ *
+ * Returns the css if there's valid one with @id, otherwise returns NULL.
+ * Should be called under rcu_read_lock().
+ */
+struct cgroup_subsys_state *css_from_id(int id, struct cgroup_subsys *ss)
+{
+ struct cgroup *cgrp;
+
+ rcu_lockdep_assert(rcu_read_lock_held() ||
+ lockdep_is_held(&cgroup_mutex),
+ "css_from_id() needs proper protection");
+
+ cgrp = idr_find(&ss->root->cgroup_idr, id);
+ if (cgrp)
+ return cgroup_css(cgrp, ss->subsys_id);
+ return NULL;
+}
+
#ifdef CONFIG_CGROUP_DEBUG
static struct cgroup_subsys_state *
debug_css_alloc(struct cgroup_subsys_state *parent_css)